CN113614568A - Upsampling and cross-correlation for time of arrival determination in passive entry/passive start systems - Google Patents
Upsampling and cross-correlation for time of arrival determination in passive entry/passive start systems Download PDFInfo
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- CN113614568A CN113614568A CN202080023785.8A CN202080023785A CN113614568A CN 113614568 A CN113614568 A CN 113614568A CN 202080023785 A CN202080023785 A CN 202080023785A CN 113614568 A CN113614568 A CN 113614568A
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- Engineering & Computer Science (AREA)
- Remote Sensing (AREA)
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Computer Networks & Wireless Communication (AREA)
- Mechanical Engineering (AREA)
- Signal Processing (AREA)
- Computer Security & Cryptography (AREA)
- Lock And Its Accessories (AREA)
- Position Fixing By Use Of Radio Waves (AREA)
- Radar Systems Or Details Thereof (AREA)
Abstract
An access system for a vehicle includes a receiver and an access module. The receiver is configured to receive a signal transmitted from the portable access device to the vehicle. The access module is configured to: generating a differential signal based on the received signal; upsampling the differential signal to generate a first upsampled signal; obtaining or generating an expected signal; upsampling the desired signal to generate a second upsampled signal; cross-correlating the first up-sampled signal with the second up-sampled signal to generate a cross-correlated signal; determining a phase difference between the first up-sampled signal and the second up-sampled signal based on the cross-correlation signal; determining a round trip time of a signal received by a receiver; and granting access to the vehicle based on the round trip time.
Description
Cross reference to technical applications
The present application claims priority from U.S. patent application No. 16/824,280 filed on 3/19/2020, which is a continuation-in-part application No. 16/598,191 filed on 10/2019, which claims benefit from U.S. provisional application No. 62/744,814 filed on 12/10/2018, U.S. provisional application No. 62/801,392 filed on 5/2/2019, and U.S. provisional application No. 62/826,212 filed on 29/3/2019. The present application also claims priority from U.S. provisional application No. 62/823,210 filed on 25.3.2019 and U.S. provisional application No. 62/826,239 filed on 29.3.2019.
Technical Field
The present disclosure relates to passive entry/passive start systems.
Background
The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Conventional passive entry/passive start (PEPS) systems allow keyless entry (keyless entry), including: if the user owns a key fob (key fob) that has been paired with an in-vehicle PEPS electronic control unit (or PEPS module), the user is provided access to various vehicle functions. As an example, a user with a key fob may engage a vehicle having a PEPS module. The key fob communicates with the PEPS module, and the PEPS module can unlock the doors of the vehicle if the key fob is authenticated. The PEPS module (i) performs an authentication process to determine whether the key fob is authorized to access the vehicle, and (ii) determines a location of the key fob relative to the vehicle. The authentication process may include the exchange of encrypted passwords or signatures. If the password or signature is correct, the key fob is determined to be authorized. The location of the key fob can be determined based on, for example, the strength of the signal received from the key fob. If the key fob is authenticated and located within an authorized area of the vehicle, access to the vehicle interior is possible without the use of a conventional key.
As another example, a user in possession of a key fob may activate a vehicle function by pressing a button on the key fob. In response to the button being pressed, the key fob communicates with the PEPS module and, if the key fob is authenticated and within a predetermined distance of the vehicle, the PEPS module performs the function associated with the button pressed on the key fob (e.g., starting the vehicle, opening the doors, setting an alert, etc.). The communications performed for these two examples may include the key fob and the PEPS module performing a one-way Low Frequency (LF) wake-up function and a one-way or two-way Radio Frequency (RF) authentication function.
A mobile phone, i.e., a key (PAK) vehicle access system, may operate similarly to the PEPs system, except that a mobile phone is used to access the vehicle instead of a key fob. For example, a mobile phone may communicate with a PAK module or a Telematics Control Unit (TCU) in a vehicle to begin an access pairing process. The mobile phone and PAK module or TCU perform an access pairing procedure to establish a trust relationship. The pairing process may includePairing, thereby: exchanging security information directly between the mobile phone and the vehicle; exchanging a mobile phone address, a mobile phone identity resolution key, a reservation identifier, and/or an encryption key via a cloud-based network; and/or the mobile phone presents the certificate to the vehicle, wherein the certificate is recognized by (i) the mobile phone, (ii) a trusted secure signing authority (such as the manufacturer of the vehicle), and/or (iii) a trusted third party. In the case of a certificate, the certificate may include an identifier of a person authorized to access the vehicle, an identifier of a cloud-based network authorized to transmit the certificate, an identifier of a rental agreement for the vehicle, an identifier of the vehicle, a date and time period that the authorized person is allowed to use the vehicle, and/or other restrictions and/or access/permission information.
For passive entry, some user action is typically required to initiate the process of waking up the key fob or the mobile phone (referred to as a portable access device). This may include, for example, a user using the portable access device to engage a vehicle and/or touching and/or pulling a door handle. When the PEPS module or PAK module (referred to as the access module) detects this behavior, the access module performs a localization procedure to start searching and wake up the key fob. In a one-way RF system, LF downlink signals (e.g., 125 kilohertz (kHz) signals) are transmitted from the access module to the key fob to wake up the key fob to transmit commands and data for authentication purposes with the key fob. The key fob then transmits the response signal to the access module via the RF uplink. The response signal may be at an ultra-high frequency (e.g., 315 megahertz (MHz) or 433 MHz). In a two-way RF system, LF downlink signals are sent from the access module to the key fob to wake up the key fob and establish a two-way RF link between the access module and the key fob. The bidirectional RF link may transmit signals at UHF frequencies (e.g., 315MHz, 422MHz, 868MHz, or 915 MHz). The key fob is then authenticated using the bi-directional RF link. The key fob includes a microcontroller that remains in a sleep mode (or low power listening mode) that continuously checks for a valid LF signal. Once a valid LF signal contains the correct vehicle-specific wake-up identifier, the microcontroller generates a signal to wake up the PEPS controller to communicate with the access module of the vehicle.
The vehicle may have, for example, 4-6 LF antennas that generate LF magnetic fields. The controller of the key fob measures the LF signal level during communication with the access module. The controller determines a Received Signal Strength Indicator (RSSI) and provides the RSSI to the access module. The access module then determines the location of the key fob based on the RSSI. The key fob includes three separate antenna coils or one 3D coil that are used to determine x, y, and z axis values indicative of the location of the key fob.
Smartphones, wearable devices, and/or other smart portable network devices may act as key fobs. The intelligent portable network device may enable various vehicle functions and distance measurement features, such as passive greeting illumination, distance limits on remote parking applications, and the like.
Disclosure of Invention
An access system for a vehicle is provided. The access system includes a receiver and an access module. The receiver is configured to receive a signal transmitted from the portable access device to the vehicle. The access module is configured to: generating a differential signal based on the received signal; upsampling the differential signal to generate a first upsampled signal; obtaining or generating an expected signal; upsampling the desired signal to generate a second upsampled signal; cross-correlating the first up-sampled signal with the second up-sampled signal to generate a cross-correlated signal; determining a phase difference between the first up-sampled signal and the second up-sampled signal based on the cross-correlation signal; determining a round trip time of a signal received by a receiver; and granting access to the vehicle based on the round trip time.
In other features, the access module is configured to: down-converting the signal to generate a down-converted signal; sampling the down-converted signal to generate a sampled signal; performing an arc tangent of the sampled signal to generate an arc tangent signal; and differentiates the arctan signal to generate a differentiated signal.
In other features, the access module is configured to: determining at least one of a location or a distance of the portable access device relative to the vehicle based on the round trip time; and granting access to the vehicle based on at least one of the location or the distance.
In other features, the access module comprises: a first upsampler configured to upsample the differential signal to generate a first upsampled signal; and a second upsampler configured to upsample the desired signal to generate a second upsampled signal. The first upsampler has the same upsampling rate as the second upsampler.
In other features, the access module comprises: a sign module configured to determine a sign of the differentiated signal; and a bit pattern module configured to generate an expected signal based on the sign of the differentiated signal.
In other features, the access module is configured to: obtaining a desired signal; and the expected signal is a predetermined signal obtained by the access module before the received signal is received.
In other features, the access module is configured to perform an iterative process comprising: multiplying bits of the first up-sampled signal and the second up-sampled signal to generate a resultant product; summing the resulting products to generate a product-sum value; and shifting the second up-sampled signal relative to the first up-sampled signal. The iterative process provides the values of the product-sum. The access module is configured to determine a phase difference based on a value of the product-sum.
In other features, the access module is configured to reconstruct the signal transmitted from the portable access device to the vehicle based on a zero crossing of a portion of the cross-correlation signal associated with a maximum of the values of the product-sum.
In other features, the access module comprises: an upsampler configured to upsample the differential signal to generate a first upsampled signal; a sign module configured to determine a sign of the first up-sampled signal; and a bit pattern module configured to generate an expected signal based on the sign of the first up-sampled signal.
In other features, a portable access device of an access system of a vehicle is provided. The portable access device includes a receiver and a control module. The receiver is configured to receive a signal transmitted from an access module of the vehicle to the portable access device. The control module is configured to: generating a differential signal based on the received signal; upsampling the differential signal to generate a first upsampled signal; obtaining or generating an expected signal; upsampling the desired signal to generate a second upsampled signal; cross-correlating the first up-sampled signal with the second up-sampled signal to generate a cross-correlated signal; determining a phase difference between the first up-sampled signal and the second up-sampled signal based on the cross-correlation signal; determining a round trip time of a signal received by a receiver; and either sending the round trip time to the vehicle to gain access to the vehicle based on the round trip time or determining and sending at least one of a location or a distance between the portable access device and the vehicle to gain access to the vehicle.
In other features, the control module is configured to: down-converting the signal to generate a down-converted signal; sampling the down-converted signal to generate a sampled signal; performing an arc tangent on the sampled signal to generate an arc tangent signal; and differentiates the arctan signal to generate a differentiated signal.
In other features, the control module is configured to: determining at least one of a location or a distance of the portable access device relative to the vehicle based on the round trip time; and transmitting the at least one of the location or the distance to the vehicle to obtain access to the vehicle based on the at least one of the location or the distance.
In other features, the control module comprises: a first upsampler configured to upsample the differential signal to generate a first upsampled signal; and a second upsampler configured to upsample the desired signal to generate a second upsampled signal, wherein the upsampling rate of the first upsampler is the same as the sampling rate of the second upsampler.
In other features, the control module comprises: a sign module configured to determine a sign of the differentiated signal; and a bit pattern module configured to generate an expected signal based on the sign of the differentiated signal.
In other features, the control module is configured to: obtaining a desired signal; and the expected signal is a predetermined signal obtained by the control module before the received signal is received.
In other features, the control module is configured to perform an iterative process comprising: multiplying bits of the first up-sampled signal and the second up-sampled signal to generate a resultant product; summing the resulting products to generate a product-sum value; and shifting the second up-sampled signal relative to the first up-sampled signal. The iterative process provides the values of the product-sum. The control module is configured to determine a phase difference based on the value of the product-sum.
In other features, the control module is configured to reconstruct a signal transmitted from an access module of the vehicle to the portable access device based on zero crossings of a portion of the cross-correlation signal associated with a maximum of the values of the plurality of product-sums.
In other features, the control module comprises: an upsampler configured to upsample the differential signal to generate a first upsampled signal; a sign module configured to determine a sign of the first up-sampled signal; and a bit pattern module configured to generate an expected signal based on the sign of the first up-sampled signal.
An access system for a vehicle is provided and includes an antenna and an access module. The antennas are configured to each receive a signal transmitted from the portable access device to the vehicle. One of the antennas is a circularly polarized antenna. The access module is configured to: down-converting the received signal to generate an in-phase signal and a quadrature-phase signal; performing a music algorithm to determine an angle of arrival of a received signal received at an antenna; determining a distance between the portable access device and the vehicle based on the angle of arrival; and granting access to the vehicle based on the distance.
In other features, an antenna includes: a circularly polarized antenna comprising a conductive annular body having an inner bore; a circular isolator connected to the conductive annular body; and a linearly polarized antenna connected to the circularly polarized antenna and the circular isolator and extending outward from the circular isolator. A linearly polarized antenna includes a sleeve (sleeve) and a conductive element extending through the sleeve. The linearly polarized antenna extends orthogonal to the radius of the circularly polarized antenna.
In other features, the access module is configured to: while performing the musical algorithm, collecting analysis signal samples of the signals received at each antenna to generate a matrix of received data; estimating a data covariance matrix based on the received data matrix; using an eigenvalue decomposition process to determine an mxm matrix based on the covariance matrix, where M is an integer greater than or equal to 2; determining a plurality of incident (impinging) signals; dividing the M matrix into a plurality of matrices; calculating a music spectrum based on one of the plurality of matrices; and performing a peak search on the music spectrum to determine an angle of arrival.
In other features, the access module is configured to: performing a covariance smoothing method to generate a modified covariance matrix; and using an eigenvalue decomposition process to determine an mxm matrix based on the modified covariance matrix.
In other features, the access module is configured to: converting the in-phase and quadrature phase sampling vectors into phase angle vectors while generating a received data matrix; generating a recreated in-phase and quadrature-phase sampling vector for each antenna based on the phase angle vector; and generating a received data matrix based on the re-created in-phase and quadrature-phase sampling vectors for each antenna.
In other features, the access module is configured to: creating time vectors corresponding to the in-phase and quadrature-phase sampling vectors; discarding some of the analysis signal samples collected around the antenna switching time; expanding each repeated part of the residual sample by a step size pi; averaging the frequencies of the remaining sampled sinusoids; finding the average slope of the remaining samples; measuring the standard deviation of the mean slope; determining which antennas are misaligned based on the measured standard deviation; and for each antenna, interpolating the straight-line points on the time vector to generate a reconstructed phase angle vector.
In other features, the access module is configured to: checking which of the antennas has an inaccurate alignment if the standard deviation is greater than a predetermined threshold; and re-measuring the standard deviation of the average slope for the antenna.
In other features, the access module is configured to perform a purging method comprising: performing an iterative process, the iterative process comprising: removing the source signals one at a time using a calibration array manifold comprising antennas; and forcing the position of the source signal to an offset position and recalculating the direction of arrival angles of the remaining signals. While performing the iterative process, the access module converges to a new set of angles of arrival of incidence.
In other features, a vehicle is provided and includes: a vehicle body; and a roof, center console, floor, or at least partially enclosed metal structure. The antenna is implemented in at least one of a vehicle roof, a center console, a floor, or an at least partially enclosed metal structure.
In other features, the antenna comprises a multi-axis polarized RF antenna assembly, wherein the multi-axis polarized RF antenna assembly comprises a circularly polarized antenna and is oriented in the vehicle roof.
In other features, a method is provided and includes: receiving a signal transmitted from a portable access device to a vehicle at each of a plurality of antennas, wherein one of the antennas is a circularly polarized antenna; down-converting the received signal to generate an in-phase signal and a quadrature-phase signal; performing a music algorithm to determine an angle of arrival of a received signal received at an antenna; determining a distance between the portable access device and the vehicle based on the angle of arrival; and granting access to the vehicle based on the distance.
In other features, the performing the musical algorithm comprises: collecting analysis signal samples of the signal received at each antenna to generate a received data matrix; estimating a data covariance matrix based on the received data matrix; using an eigenvalue decomposition process to determine an mxm matrix based on the covariance matrix, where M is an integer greater than or equal to 2; determining a plurality of incident signals; dividing the M matrix into a plurality of matrices; calculating a music spectrum based on one of the plurality of matrices; and performing a peak search on the music spectrum to determine an angle of arrival.
In other features, the method further comprises: performing a covariance smoothing method to generate a modified covariance matrix; and using an eigenvalue decomposition process to determine an mxm matrix based on the modified covariance matrix.
In other features, the method further comprises: converting the in-phase and quadrature phase sampling vectors into phase angle vectors while generating a received data matrix; generating a recreated in-phase and quadrature-phase sampling vector for each antenna based on the phase angle vector; and generating a received data matrix based on the re-created in-phase and quadrature-phase sampling vectors for each antenna.
In other features, the method further comprises: creating time vectors corresponding to the in-phase and quadrature-phase sampling vectors; discarding some of the analysis signal samples collected around the antenna switching time; expanding each repeated part of the residual sample by a step size pi; averaging the frequencies of the remaining sampled sinusoids; determining an average slope of the remaining samples; measuring the standard deviation of the mean slope; determining which antennas are misaligned based on the measured standard deviation; and for each antenna, interpolating the straight-line points on the time vector to generate a reconstructed phase angle vector.
In other features, the method further comprises: checking which of the antennas has an inaccurate alignment if the standard deviation is greater than a predetermined threshold; and re-measuring the standard deviation of the average slope for the antenna.
In other features, the method further comprises performing a purging method comprising: performing an iterative process, the iterative process comprising: removing the source signals one at a time using a calibration array manifold comprising antennas and forcing the position of the source signals to an offset position and recalculating the directional angle of arrival of the remaining signals; and converging to a new set of angles of arrival of incidence while performing the iterative process.
In other features, the vehicle includes (i) a body and (ii) a roof, center console, floor, or at least partially enclosed metal structure. The antenna is implemented in at least one of a vehicle roof, a center console, a floor, or an at least partially enclosed metal structure.
In other features, the antenna comprises a multi-axial polarized RF antenna assembly. A multi-axis polarized RF antenna assembly includes a circularly polarized antenna and is oriented in the vehicle roof.
An access system for a vehicle is provided. The access system includes an antenna and an access module. The antennas are configured to each receive a signal transmitted from the portable access device to the vehicle. The signal is transmitted at a frequency of 2.4 GHz. The access module is configured to: down-converting the received signal to generate an in-phase signal and a quadrature-phase signal; performing carrier phase based ranging, including implementing a musical algorithm to (i) determine a distance between the portable access device and the vehicle, and (ii) determine an angle of arrival of a received signal received at the antenna; determining a location of the portable access device relative to the vehicle based on the distance and the angle of arrival; and granting access to the vehicle based on the location.
In other features, the antenna is disposed in the vehicle such that the received signal has a plurality of corresponding bounce paths between the portable access device and the antenna.
In other features, the antenna is disposed in a metal structure of the vehicle.
In other features, the antenna is positioned such that there is no line of sight between the antenna and the portable access device.
In other features, the access system further comprises sensors, wherein each sensor comprises two or more antennas, and wherein the sensors are disposed in the vehicle such that the received signal has a plurality of corresponding bounce paths between the portable access device and each sensor.
In other features, the access module is configured to: monitoring the received signal and generating a received signal strength indication based on the received signal; determining whether the portable access device is inside or outside the vehicle based on the received signal strength indication; and determining a distance between the portable access device and the vehicle when the portable access device is outside the vehicle.
In other features, at least one antenna is a circularly polarized antenna.
In other features, an antenna includes: a circularly polarized antenna comprising a conductive annular body having an inner bore; a circular isolator connected to the conductive annular body; and a linearly polarized antenna connected to the circularly polarized antenna and the circular isolator and extending outward from the circular isolator. A linearly polarized antenna includes a sleeve and a conductive element extending through the sleeve. The linearly polarized antenna extends orthogonal to the radius of the circularly polarized antenna.
In other features, the access module is configured to: while implementing the musical algorithm, collecting analysis signal samples of the signals received at each antenna to generate a matrix of received data; estimating a data covariance matrix based on the received data matrix; using an eigenvalue decomposition process to determine an mxm matrix based on the covariance matrix, where M is an integer greater than or equal to 2; determining a plurality of incident signals; dividing the M matrix into a plurality of matrices; calculating a music spectrum based on one of the plurality of matrices; and performing a peak search on the music spectrum to determine an angle of arrival.
In other features, the receiver includes a phase locked loop and is phase locked with a transmitter of the portable access device. The access module is configured to perform a tone swap with the transmitter and determine at least one of a distance or an angle of arrival based on the tone swap.
In other features, the receiver includes a phase locked loop and is phase locked with a transmitter of the portable access device. The access module is configured to: performing a tone swap with a transmitter and determining round-trip time-of-flight information based on the tone swap; and determining the distance based on the round trip time of flight information.
In other features, a vehicle is provided and includes: accessing the system; a vehicle body; and a roof, center console, floor, or at least partially enclosed metal structure. The antenna is implemented in at least one of a vehicle roof, a center console, a floor, or an at least partially enclosed metal structure.
In other features, a method is provided and includes: receiving a signal transmitted from the portable access device to the vehicle at each of the plurality of antennas, wherein the signal is transmitted at a frequency of 2.4 GHz; down-converting the received signal to generate an in-phase signal and a quadrature-phase signal; performing carrier phase based ranging, including implementing a musical algorithm to (i) determine a distance between the portable access device and the vehicle, and (ii) determine an angle of arrival of a received signal received at the antenna; determining a location of the portable access device relative to the vehicle based on the distance and the angle of arrival; and granting access to the vehicle based on the location.
In other features, the antenna is disposed in the vehicle such that the received signal has a plurality of corresponding bounce paths between the portable access device and the antenna.
In other features, the antenna is positioned such that there is no line of sight between the antenna and the portable access device.
In other features, the antenna pairs are implemented as part of respective sensors. The sensors are disposed in the vehicle such that the received signal has a plurality of corresponding bounce paths between the portable access device and each sensor.
In other features, the method further comprises: monitoring the received signal and generating a received signal strength indication based on the received signal; determining whether the portable access device is inside or outside the vehicle based on the received signal strength indication; and determining a distance between the portable access device and the vehicle when the portable access device is outside the vehicle.
In other features, at least one antenna is a circularly polarized antenna.
In other features, the method further comprises: in implementing a music algorithm, collecting analytic signal samples of the signals received at each antenna to generate a received data matrix; estimating a data covariance matrix based on the received data matrix; using an eigenvalue decomposition process to determine an mxm matrix based on the covariance matrix, where M is an integer greater than or equal to 2; determining a plurality of incident signals; dividing the M matrix into a plurality of matrices; calculating a music spectrum based on one of the plurality of matrices; and performing a peak search on the music spectrum to determine an angle of arrival.
In other features, the method further comprises: performing a tone exchange with a transmitter of a portable access device; and determining at least one of a distance or an angle of arrival based on the tone swap. The receiver of the portable access device performing the tone switching includes a phase locked loop and is phase locked with the transmitter of the portable access device.
In other features, the method further comprises: performing a tone swap with a transmitter and determining round-trip time-of-flight information based on the tone swap; and determining the distance based on the round trip time of flight information. The receiver of the portable access device performing the tone switching includes a phase locked loop and is phase locked with the transmitter of the portable access device.
A multi-axis polarized RF antenna assembly is provided that includes a circularly polarized antenna, a circular isolator, and a linearly polarized antenna. A circularly polarized antenna includes a conductive annular body having an inner bore. The circular separator is connected to the conductive ring body. The linearly polarized antenna is connected to the circularly polarized antenna and the circular isolator, and extends outward from the circular isolator. A linearly polarized antenna includes a sleeve and a conductive element extending through the sleeve. The linearly polarized antenna extends orthogonal to the radius of the circularly polarized antenna.
In other features, the conductive element is a wire. In other features, the sleeve is formed from polytetrafluoroethylene. The conductive elements are formed of copper.
In other features, the linearly polarized antenna is configured to extend downward from the circularly polarized antenna when in use.
In other features, the circularly polarized antenna is a 2-axis antenna. The linearly polarized antenna is a single axis antenna.
In other features, the multi-axis polarized RF antenna assembly further comprises a ground plane. A circular isolator is disposed on the ground plane between the conductive element and the ground plane and between the circularly polarized antenna and the ground plane.
In other features, the circularly polarized antenna includes two feed points that are phase-shifted by 90 ° and is configured to receive signals that are 90 ° out of phase with each other.
In other features, a vehicle is provided that includes a body and a roof. The vehicle roof includes a multi-axial polarized RF antenna assembly. A multi-axis polarized RF antenna assembly is oriented in the vehicle roof such that the linearly polarized antenna extends downward from the circularly polarized antenna.
In other features, a vehicle system is provided that includes a multi-axis polarized RF antenna assembly, a second multi-axis polarized RF antenna assembly, and an access module. The multi-axial polarized RF antenna assembly is a first multi-axial polarized RF antenna assembly and is configured to be implemented in a vehicle. The second multi-axial polarized RF antenna assembly is configured to be implemented in a vehicle and includes: a second circularly polarized antenna comprising a second conductive loop body having a second inner bore; a second circular isolator connected to the second conductive ring body; and a second linearly polarized antenna connected to and extending outwardly from the second circular isolator. The second linearly polarized antenna includes a sleeve and a conductive element extending through the sleeve of the second linearly polarized antenna. The second linearly polarized antenna extends orthogonal to a radius of the second circularly polarized antenna. The access module is connected to the first and second multi-axis polarized RF antenna assemblies and is configured to communicate with the portable access device via the first and second multi-axis polarized RF antenna assemblies.
In other features, at any one time at least one of the linearly polarized antenna or the first multi-axis polarized RF antenna assembly is not cross-polarized with an antenna of the second multi-axis polarized RF antenna assembly.
In other features, the access module is configured to perform a passive entry passive start operation or a mobile phone or key operation, including: transmitting and receiving radio frequency signals via a first one of the multi-axis polarized RF antenna assemblies and a second one of the multi-axis polarized RF antenna assemblies.
In other features, the access module is configured to grant access to the vehicle based on the radio frequency signal.
In other features, the access module is configured to execute an algorithm to determine which antenna pair having a first one of the multi-axis polarized RF antenna assemblies and a second one of the multi-axis polarized RF assemblies is to be used for communicating with the portable access device. In other features, the portable access device is a key fob or a cellular telephone.
In other features, a method of communicating with a portable access device is provided. The method includes iteratively executing an algorithm via an access module of the vehicle, wherein the algorithm includes a series of operations including: selecting a frequency from the frequencies; selecting an antenna pair from the possible antenna pairs; wherein the antennas of the possible antenna pairs comprise antennas having different polarization axes; transmitting the packet to the portable access device via the selected antenna pair; receiving a first received signal strength indicator, RSSI, and a response signal from the portable access device, wherein the first RSSI corresponds to transmission of the packet; and measuring a second RSSI of the response signal. Based on the first and second RSSIs, an optimal frequency of the frequencies and an optimal antenna pair of the possible antenna pairs are selected. One or more additional packets are transmitted using the selected best frequency and the selected best antenna pair.
In other features, each selected antenna pair includes one of linearly polarized antennas and one of circularly polarized antennas.
In other features, the method of claim 1, further comprising: transmitting the one or more additional packets to authorize the portable access device; determining whether the portable access device is authorized to access an interior of the vehicle; if the portable access device is authorized, access to the vehicle interior is granted.
In other features, the method further comprises: measuring time of flight of the one or more additional packets, comprising: a time to transmit the one or more additional packets to the portable access device and a time to receive one or more responses from the portable access device; and estimating a distance between the vehicle and the portable access device based on the measured time of flight.
In other features, the estimated distance is used to detect whether another device is attempting to perform a range extension type relay station (range extension type relay station) attack. In other features, the method of claim 4, further comprising: if another device is attempting to perform a range-extended relay attack, countermeasures are performed, including preventing access to the interior of the vehicle. In other features, the countermeasure includes notifying an owner of the vehicle of the extended range relay attack.
In other features, the method further comprises: exchanging a plurality of unmodulated carrier tone pairs with a portable access device on a plurality of frequencies, wherein the unmodulated carrier tone pairs include a receive tone and a transmit tone; measuring the phase of the received tone relative to the transmitted tone and collecting frequency data; and estimating a distance between the vehicle and the portable access device based on the measured phase and frequency data.
In other features, the method comprises: determining whether another device is attempting to perform a range-extended relay attack based on the estimated distance. In other features, each selected antenna pair comprises a linearly polarized antenna.
In other features, the algorithm includes switching between possible pairs of antennas between consecutively transmitted packets. In other features, the algorithm includes switching between possible pairs of antennas during transmission of a portion of the packet. In other features, the portion of the packet is a continuous wave tone.
In other features, some of the possible antenna pairs include two antennas that are co-located.
In other features, the method further comprises: transmitting the packet to the portable access device; measuring a time-of-flight value for a packet based on a response signal received from the portable access device, wherein the response signal is transmitted based on the packet; determining whether another device is performing a range extension type (relay type) relay attack based on the time-of-flight value; and preventing access to an interior of the vehicle in response to detecting the range-extended relay attack.
In other features, the portable access device is a key fob or a cellular telephone. In other features, the method further comprises encrypting the identifier of the best antenna pair. The transmission of the one or more additional packets includes an encrypted identifier of the best antenna pair.
In other features, a vehicle system for communicating with a portable access device is provided. The vehicle system includes an access module and antennas having different polarization axes. The access module is configured to iteratively execute the algorithm. The algorithm includes a series of operations including: selecting a frequency from a plurality of frequencies; selecting an antenna pair from antennas having different polarization axes; transmitting the packet to the portable access device via the selected antenna pair; receiving a first RSSI and a response signal from the portable access device, wherein the first RSSI corresponds to a transmission of a packet; and measuring a second RSSI of the response signal. The access module is configured to: selecting an optimal frequency of the frequencies and an optimal antenna pair of the antenna pairs based on the first RSSI and the second RSSI; and transmitting one or more additional packets using the selected best frequency and the selected best antenna pair.
In other features, the access module is configured to: measuring time of flight of the one or more additional packets, comprising: a time to transmit the one or more additional packets to the portable access device and a time to receive one or more responses from the portable access device; and estimating a distance between the vehicle and the portable access device based on the measured time of flight.
In other features, the access module is configured to: exchanging a plurality of pairs of unmodulated carrier tones with the portable access device at a plurality of frequencies, wherein the unmodulated carrier tones include receive tones and transmit tones; measuring a phase of the received tone relative to the transmitted tone; collecting measured phase and frequency data; and estimating a distance between the vehicle and the portable access device using the measured phase and frequency data.
In other features, the access module is configured to detect whether the portable access device is attempting to perform an extended range relay attack based on the estimated distance.
In other features, the access module is configured to detect whether the device is attempting to perform a range-extended relay attack based on the estimated distance.
In other features, the access module is configured to: if the portable access device is attempting to perform a range-extended relay attack, countermeasures are performed, including preventing access to the interior of the vehicle.
In other features, the countermeasure comprises: the owner of the vehicle is notified of the extended range relay attack. In other features, the portable access device is a key fob or a cellular telephone.
In other features, the portable access device is configured to encrypt the identifier of the optimal antenna pair. The transmission of the one or more additional packets includes an encrypted identifier of the best antenna pair.
In other features, a system for detecting a range-extended relay attack is provided. The system includes a first transmitter, a receiver, and a first module. The first transmitter is configured to transmit a first radio frequency signal from one of the vehicle and the portable access device to the other of the vehicle and the portable access device. The receiver is configured to receive a first response signal from one of the vehicle and the portable access device in response to the first radio frequency signal. The first module is configured to: monitoring or generating one or more parameters associated with the transmission of the first radio frequency signal and the reception of the first response signal; based on the one or more parameters, detecting a range-extended relay attack performed by the attacking device for at least one of gaining access to the vehicle or operational control of the vehicle, wherein at least one of: (i) the first radio frequency signal is relayed from the vehicle to the portable access device via the attack device, or (ii) the first response signal is relayed from the portable access device to the vehicle via the attack device; and performing a countermeasure in response to detecting the range-extended relay attack.
In other features, the first module is implemented at a vehicle. In other features, the first module is implemented at a portable access device.
In other features, the first module is configured to: measuring the round trip time of the first radio frequency signal; and detecting the extended range type relay attack based on the round trip time.
In other features, the first module is configured to: transmitting a second radio frequency signal and receiving a second response signal prior to the transmission of the first radio frequency signal and the reception of the first response signal; monitoring at least one of: a first received signal strength indicator of a second radio frequency signal or a second received signal strength indicator of a second response signal; and determining at least one of a path, a frequency, a channel, or a pair of antennas for transmitting the first radio frequency signal and receiving the first response signal based on at least one of the first received signal strength indicator or the second received signal strength indicator.
In other features, the first module is configured to: transmitting a second radio frequency signal and receiving a second response signal prior to the transmission of the first radio frequency signal and the reception of the first response signal; monitoring an antenna polarization state corresponding to at least one of the second radio frequency signal or the second response signal; and determining at least one of a path, a frequency, a channel, or an antenna pair for transmission of the first radio frequency signal and reception of the first response signal based on an antenna polarization state of at least one of the first radio frequency signal or the first response signal.
In other features, the first module is configured to transmit the first radio frequency signal upon receiving the first response signal or the second radio frequency signal from one of the vehicle and the portable access device.
In other features, the first module is configured to receive the first response signal upon receiving the second radio frequency signal from one of the vehicle and the portable access device.
In other features, the first module is configured to: determining a series of randomly selected frequencies or channels; sharing the series of randomly selected frequencies or channels with one of the vehicle and the portable access device; and transmitting a first radio frequency signal and receiving a first response signal based on the randomly selected frequency or channel.
In other features, the first module is configured to: randomizing an access address for a vehicle or portable access device; sharing the randomized access address with the portable access device; and generating the first radio frequency signal to include one of the access addresses.
In other features, the first module is configured to: measuring a length of at least one bit of the first response signal; and detecting an extended range relay attack based on the length of the at least one bit.
In other features, the first module is configured to: monitoring the slopes of the rising edge and the falling edge of the first response signal; and detecting an extended range relay attack based on the slope.
In other features, the first module is configured to: the first response signal is aligned with an idealized gaussian waveform for a known target pattern and bit rate (including a scaling peak and an alignment zero offset) using a sliding correlation function (sliding correlation function), and based on the alignment, a range-extended relay attack is detected.
In other features, the first module is configured to: accumulating a portion of the predetermined waveform of the first response signal immediately after the zero crossing and before a next peak; determining an average value based on the accumulated portion; and detecting an extended range type relay attack based on the average value.
In other features, the first module is configured to: accumulating a portion of the first response signal after a peak of the predetermined waveform and before a next zero-crossing; determining an average value based on the accumulated portion; and detecting an extended range type relay attack based on the average value.
In other features, the first module is configured to randomize a direction of travel of the first radio frequency signal, including whether the first radio frequency signal is transmitted from the vehicle to the portable access device or from the portable access device to the vehicle.
In other features, the countermeasure includes at least one of preventing access to the vehicle or performing operational control on the vehicle.
In other features, the system further comprises a second transmitter configured to transmit a dummy signal when the first transmitter transmits the first radio frequency signal or the receiver receives the first response signal.
In other features, the method comprises: a first module implemented at a vehicle; and a portable access device comprising a second module. The first module is configured to transmit a first radio frequency signal to the portable access device and receive a first response signal from the portable access device. The second module is configured to transmit a second radio frequency signal to the vehicle and receive a second response signal from the vehicle. The first module transmits the first radio frequency signal and the second module transmits the first response signal or the second radio frequency signal, or the first module receives the first response signal and the second module transmits the second radio frequency signal.
In other features, the first module and the second module are configured to: exchanging at least three pairs of radio signals containing portions of unmodulated carrier tones, wherein the unmodulated carrier tones include receive tones and transmit tones; and measuring the phase of the received tone relative to the transmitted tone. One or more of the first module and the second module are configured to: collecting frequency and phase information; and estimating a distance between the first module and the second module based on the phase and frequency information.
In other features, one or more of the first module and the second module are configured to detect the range-extended relay attack using the estimated distance.
In other features, a method of detecting a range-extended relay attack is provided. The method comprises the following steps: transmitting a radio frequency signal from one of the vehicle and the portable access device to the other of the vehicle and the portable access device via a transmitter; receiving, via a receiver, a response signal from one of the vehicle and the portable access device in response to the radio frequency signal; monitoring or generating one or more parameters associated with the transmission of the radio frequency signal and the reception of the response signal; and detecting, based on the one or more parameters, an extended range relay attack performed by the attacking device to obtain at least one of access to the vehicle or operational control of the vehicle. There is at least one of: (i) the first radio frequency signal is relayed from the vehicle to the portable access device via the attack device, or (ii) the first response signal is relayed from the portable access device to the vehicle via the attack device. The method further comprises the following steps: performing a countermeasure in response to detecting the range-extended relay attack; measuring the round trip time of the radio frequency signal; monitoring at least one of a first received signal strength indicator of a radio frequency signal or a second received signal strength indicator of a response signal; and detecting the extended-range relay attack based on the round-trip time.
In other features, a system for accessing a vehicle or providing operational control of a vehicle is provided. The system includes a master device, the master device including: a first antenna module including a first antenna having different polarization axes; a transmitter configured to transmit a challenge signal (challenge signal) from the vehicle to a slave device via the first antenna module, wherein the slave device is a portable access device; and a first receiver configured to receive a response signal from the slave device in response to the challenge signal. The system further comprises a first sniffer device comprising: a second antenna module including a second antenna having a different polarization axis; and a second receiver configured to receive the challenge signal from the transmitter and the response signal from the slave device via the second antenna module. The first sniffer device is configured to measure when the challenge signal and the response signal arrive at the first sniffer device to provide a time of arrival. The master device or the first sniffer device is configured to (i) estimate at least one of a distance from the vehicle to the slave device or a position of the slave device relative to the vehicle based on the time of arrival, and (ii) prevent at least one of access to the vehicle or operational control of the vehicle based on the at least one of the estimated distance or position.
In other features, the master device or the first sniffer device is configured to: determining a round trip time associated with the sending of the challenge signal based on the time of arrival; and detecting, based on the round trip time, an extended range type relay attack performed by the attack apparatus for obtaining at least one of access to the vehicle or operation control of the vehicle. The response signal is relayed by the attacking device from the slave device to the vehicle and altered by the attacking device. The master device is configured to perform a countermeasure in response to detection of the extended range type relay attack.
In other features and at any time, at least one of the first antennas of the first antenna module is not cross-polarized with at least one of the second antennas of the second antenna module.
In other features and at any time, at least one of the first antennas of the first antenna module is not cross-polarized with an antenna of the slave device.
In other features, the master device or the first sniffer device is configured to: determining a first amount of time that the first sniffer device receives the challenge signal and a second amount of time that the sniffer device receives the response signal; and estimating the distance based on the first amount of time and the second amount of time.
In other features, the system further comprises a second sniffer and a third sniffer. The second sniffer device comprises a third antenna module comprising a third antenna and a third receiver configured to receive the challenge signal from the transmitter and the response signal from the slave device via the third antenna module. The third sniffer device comprises a fourth antenna module comprising a fourth antenna and a fourth receiver configured to receive via the fourth antenna module the challenge signal from the transmitter and the response signal from the slave device. The second sniffer device is configured to measure when the challenge signal and the response signal arrive at the second sniffer device to provide a time of arrival. The third sniffer device is configured to measure when the challenge signal and the response signal arrive at the third sniffer device to provide a time of arrival. The primary device, the first sniffer device, the second sniffer device or the third sniffer device is configured to estimate the position based on the time of arrival provided by the first sniffer device, the time of arrival provided by the second sniffer device and the time of arrival provided by the third sniffer device.
In other features, the first sniffer device is configured to determine a first amount of time to receive the response signal for the first sniffer device. The second sniffer device is configured to determine a second amount of time to receive the response signal for the second sniffer device. The third sniffer device is configured to determine a third amount of time to receive the response signal for the third sniffer device. The primary device, the first sniffer device, the second sniffer device, or the third sniffer device is configured to estimate the location based on the first amount of time, the second amount of time, and the third amount of time.
In other features, the master device is configured to periodically send a challenge signal or other challenge signal to the slave device and receive a corresponding response signal from the slave device. The first sniffer device is configured to measure when the challenge signal and the response signal arrive at the first sniffer device to provide corresponding arrival times. The master device or the first sniffer device is configured to (i) update at least one of a distance or a location based on the arrival time associated with the challenge signal and the response signal, and (ii) prevent at least one of access to the vehicle or operational control of the vehicle based on the at least one of the updated distance or the updated location.
In other features, a method for accessing a vehicle or providing operational control of a vehicle is provided. The method comprises the following steps: transmitting a challenge signal from a master device to a slave device of a vehicle via a first antenna module, wherein the first antenna module includes first antennas having different polarization axes; receiving, at a first receiver, a response signal from a slave device in response to the challenge signal; receiving, at the first sniffer device, via a second antenna module and a second receiver, a challenge signal from the master device and a response signal from the slave device, wherein the second antenna module comprises a second antenna having a different polarization axis; measuring when a challenge signal and a response signal are received at the first sniffer device to provide a time of arrival via the first sniffer device; estimating at least one of a distance from the vehicle to the slave device or a position of the slave device relative to the vehicle based on the time of arrival; and preventing at least one of access to or operational control of the vehicle based on the at least one of the estimated distance or position.
In other features, the method comprises: determining a round trip time associated with the sending of the challenge signal based on the time of arrival; detecting, based on the round trip time, an extended range type relay attack performed by the attacking device for at least one of gaining access to the vehicle or operational control of the vehicle, wherein the response signal is relayed from the slave device to the vehicle by the attacking device and altered by the attacking device; and performing a countermeasure in response to detecting the range-extended relay attack.
In other features and at any time, at least one of the first antennas of the first antenna module is not cross-polarized with at least one of the second antennas of the second antenna module.
In other features and at any time, at least one of the first antennas of the first antenna module is not cross-polarized with an antenna of the slave device.
In other features, the method further comprises: determining a first amount of time to receive a challenge signal for a first sniffer device and a second amount of time to receive a response signal for the sniffer device; and estimating the distance based on the first amount of time and the second amount of time.
In other features, the method further comprises: receiving, via a third antenna module, the challenge signal from the transmitter and the response signal from the slave device at a third receiver of the second sniffer device, wherein the third antenna module comprises a third antenna having a different polarization axis; and receiving, via a fourth antenna module, the challenge signal from the transmitter and the response signal from the slave device at a fourth receiver of the third sniffer device. The fourth antenna module includes a fourth antenna having a different polarization axis. The method further comprises the following steps: measuring when the challenge signal and the response signal arrive at the second sniffer device to provide a time of arrival via the second sniffer device; measuring when the challenge signal and the response signal arrive at the third sniffer device to provide a time of arrival via the third sniffer device; and estimating the location based on the time of arrival provided by the first sniffer device, the time of arrival provided by the second sniffer device and the time of arrival provided by the third sniffer device.
In other features, the method further comprises: determining a first amount of time to receive a response signal for a first sniffer device; determining a second amount of time to receive a response signal for a second sniffer device; determining a third amount of time to receive a response signal for a third sniffer device; and estimating a location based on the first amount of time, the second amount of time, and the third amount of time.
In other features, a challenge signal or other challenge signal is periodically transmitted from the master device to the slave device, and a corresponding response signal is received from the slave device; measuring, at the first sniffer device, when the challenge signal and the response signal arrive at the first sniffer device to provide corresponding arrival times; updating at least one of a distance or a position based on arrival times associated with the challenge signal and the response signal; and preventing at least one of access to or operational control of the vehicle based on at least one of the updated distance or the updated position.
In other features, a system for accessing a vehicle or providing operational control of a vehicle is provided. The system includes a first network device and a control module. The first network device includes a first antenna module, a transmitter, and a receiver. The first antenna module includes antennas having different polarization axes. The transmitter is configured to transmit a series of tones from the vehicle to the second network device via the first antenna module, and to vary a frequency of the tones during transmission of the series of tones. At any moment, at least one of the antennas of the first antenna module is not cross-polarized with the antenna of the second network device. The receiver is configured to receive the series of tones from the second network device. The control module is configured to (i) determine a contrast between a phase difference of the series of tones and a frequency difference of the series of tones, (ii) determine a distance between the first network device and the second network device based on the phase difference and the frequency difference, and (iii) prevent at least one of access to the vehicle or operational control of the vehicle based on the distance.
In other features, the control module is configured to: for each of the tones, changing the corresponding frequency during transmission of the tone; generating a curve relating phase variation of each of the tones to frequency variation for the tones, respectively; determining the slope of the curve; and determining the distance based on the slope of the curve.
In other features, the control module randomizes a channel selected for transmitting the series of tones.
In other features, the control module randomizes a direction in which tones are transmitted between the first network device and the second network device. The tones include one or more tones in the series of tones.
In other features, the control module is configured to: transmitting and receiving a series of tones via a transmitter and a receiver; and determining a distance based on the phase difference of the series of tones and the corresponding frequency difference.
In other features, the system further comprises a second network device. The first network device includes a first tone switch responder and a first tone switch initiator. The first tone switching initiator comprises a transmitter. The first tone switch responder includes a receiver. The second network device includes a second tone switch responder and a second tone switch initiator. The second tone swap responder responds to the series of tones by sending the series of tones or a second series of tones back to the first tone swap initiator. The second tone swap initiator sends a third series of tones to the first tone swap response.
In other features, the control module is configured to determine the distance based on at least one of: (i) a phase difference of the second series of tones and a frequency difference of the second series of tones, or (ii) a phase difference of the third series of tones and a frequency difference of the third series of tones.
In other features, the first network device is implemented within a vehicle. The second network device is a portable access device.
In other features, the first network device transmits two symbols to the second network device at two different frequencies simultaneously. Both symbols are less than or equal to 1us in length to prevent a successful attack.
In other features, the clock timing of the first network device and the second network device are synchronized. The first network device transmits a first symbol to a second network device at a first frequency. The second network device transmits the second symbol to the first network device simultaneously with the first network device transmitting the first symbol to the second network device. The first symbol and the second symbol are each less than or equal to 1us in length to prevent a successful attack.
In other features, a method of accessing a vehicle or providing operational control of a vehicle is provided. The method comprises the following steps: transmitting a series of tones from a first network device to a second network device via a transmitter and a first antenna module and varying the frequency of the tones during the transmission of the series of tones, wherein the first antenna module comprises an antenna, and wherein at any time at least one of the antennas of the first antenna module is not cross-polarized with the antenna of the second network device; receiving, at a receiver in the vehicle, the series of tones from a second network device; determining a phase difference of the series of tones and a frequency difference of the series of tones; determining a distance between the first network device and the second network device based on the phase difference and the frequency difference; and preventing at least one of access to the vehicle or operational control of the vehicle based on the distance.
In other features, the method further comprises: for each of the tones, changing the corresponding frequency during transmission of the tone; generating a curve relating the phase variation of each tone to the frequency variation for the tones, respectively; determining the slope of the curve; and determining the distance based on the slope of the curve.
In other features, the method further comprises randomizing a channel selected for transmitting the series of tones.
In other features, the method further comprises randomizing a direction in which tones are transmitted between the first network device and the second network device. The tones include one or more tones in the series of tones.
In other features, the method further comprises: transmitting and receiving a series of tones via a transmitter and a receiver; and determining a distance based on the phase difference of the series of tones and the corresponding frequency difference.
In other features, the method further comprises: responding to the series of tones via a second tone switching responder of the second network device by sending the series of tones or a second series of tones back to a first tone switching initiator of the first network device, wherein the first tone switching initiator comprises a transmitter; and transmitting the third series of tones to a first tone swap responder of the first network device via a second tone swap initiator of the second network device, wherein the first tone swap responder comprises a receiver.
In other features, the method further comprises determining the distance based on at least one of: (i) a phase difference of the second series of tones and a frequency difference of the second series of tones, or (ii) a phase difference of the third series of tones and a frequency difference of the third series of tones.
In other features, the first network device is implemented in a vehicle. The second network device is a portable access device.
In other features, a system for accessing a vehicle or providing operational control of a vehicle is provided. The system includes an initiator device and a sniffer device. The initiator device includes: a first antenna module comprising a plurality of polarized antennas; a transmitter configured to transmit a first tone signal from the vehicle to a responder device via a first antenna module, wherein the responder device is a portable access device; a first receiver configured to receive a second tone signal from the responder device in response to the first tone signal. The sniffer device comprises: a second antenna module comprising a plurality of polarized antennas; and a second receiver configured to receive the first tone signal from the transmitter and the second tone signal from the responder device via the second antenna module. The sniffer device is configured to determine the state of the first and second tone signals comprising respective phase delays. The initiator device or the sniffer device is configured to (i) estimate at least one of a first distance from the vehicle to the responder device or a second distance from the responder device to the sniffer device based on states of the first tone signal and the second tone signal including respective phase delays; and (ii) prevent at least one of access to or operational control of the vehicle based on the estimated at least one of the first distance or the second distance.
In other features, the initiator device or the sniffer device is configured to estimate a first distance and a second distance and prevent at least one of access to the vehicle or operational control of the vehicle based on the first distance and the second distance.
In other features, the initiator device or the sniffer device is configured to detect a range-extended relay attack performed by the attack device to obtain at least one of access to the vehicle or operational control of the vehicle based on at least one of the first distance or the second distance. The second tone signal is relayed from the responder device to the vehicle and altered by the attacking device. The initiator device is configured to perform a countermeasure in response to detecting the range-extended relay attack.
In other features and at any time, at least one of the plurality of polarized antennas of the first antenna module is not cross-polarized with at least one of the plurality of polarized antennas of the second antenna module.
In other features and at any time, at least one of the plurality of polarized antennas of the first antenna module is not cross-polarized with an antenna of the responder device.
In other features, the initiator device or the sniffer device is configured to: determining a first amount of time to travel from the initiator device to the responder device for the first tone signal based on a state of the first tone signal as received at the responder device; determining a second amount of time to travel from the responder device to the sniffer device for the second tone signal based on a state of the second tone signal as received at the sniffer device; and estimating the first distance and the second distance based on the first amount of time and the second amount of time.
In other features, the initiator device or the sniffer device is configured to: generating a first representation of the first tone signal as received at the responder device in a natural logarithmic form; generating a second representation of the first tone signal as received at the sniffer device in a natural logarithmic form; generating a third representation of the second pitch signal as received at the sniffer device in natural logarithmic form; and estimating a first distance and a second distance based on the first representation, the second representation, and the third representation.
In other features, a method for accessing a vehicle or providing operational control of a vehicle is provided. The method comprises the following steps: transmitting a first tone signal from an initiator device of the vehicle to a responder device via a first antenna module, wherein the first antenna module comprises a plurality of polarized antennas, and wherein the responder device is a portable access device; receiving, at the initiator device, a second tone signal from the responder device in response to the first tone signal; receiving, at the sniffer device and via a second antenna module, the first tone signal from the transmitter and the second tone signal from the responder device, wherein the second antenna module comprises a plurality of polarized antennas; determining, at the sniffer, states of the first and second tone signals comprising respective phase delays; estimating at least one of a first distance from the vehicle to the responder device or a second distance from the responder device to the sniffer device based on states of the first tone signal and the second tone signal including respective phase delays; and at least one of preventing access to or performing operational control on the vehicle based on the estimated at least one of the first distance or the second distance.
In other features, the method comprises: estimating a first distance and a second distance; and at least one of preventing access to the vehicle or performing operational control on the vehicle based on the first distance and the second distance.
In other features, the method further comprises: detecting, based on at least one of the first distance or the second distance, a range-extended relay attack performed by the attacking device to obtain at least one of access to the vehicle or operational control of the vehicle, wherein the second tone signal is relayed from the responder device to the vehicle and is changed by the attacking device; and performing a countermeasure in response to detecting the range-extended relay attack.
In other features and at any time, at least one of the plurality of polarized antennas of the first antenna module is not cross-polarized with the linearly polarized antenna or at least one of the plurality of polarized antennas.
In other features and at any time, at least one of the plurality of polarized antennas of the first antenna module is not cross-polarized with an antenna of the responder device.
In other features, the method further comprises: determining a first amount of time to travel from the initiator device to the responder device for the first tone signal based on a state of the first tone signal as received at the responder device; determining a second amount of time to travel from the responder device to the sniffer device for the second tone signal based on a state of the second tone signal as received at the sniffer device; and estimating the first distance and the second distance based on the first amount of time and the second amount of time.
In other features, a system for accessing a vehicle or providing operational control of a vehicle is provided. The system includes a first network device and a control module. The first network device includes a first antenna module and a control module. The first antenna module includes: a plurality of polarized antennas; a transmitter configured to transmit an initiator packet from the vehicle to the second network device via the first antenna module, wherein the initiator packet includes a synchronous access word (word) and a first Continuous Wave (CW) tone, wherein one of the first network device and the second network device is implemented within the vehicle, and wherein the other of the first network device and the second network device is a portable access device, and wherein at any time at least one of the plurality of polarized antennas of the first antenna module is not cross-polarized with an antenna of the second network device; a receiver configured to receive a response packet from the second network device, wherein the response packet includes the synchronization access word and the first CW tone. The control module is configured to: (i) determining that a round-trip timing difference between the initiator packet and the response packet is greater than a predetermined threshold; (ii) detecting an extended range type relay attack performed by the attack apparatus for at least one of gaining access to the vehicle or controlling operation of the vehicle, based on the round trip timing difference being greater than a predetermined threshold; and (iii) at least one of prevent access to the vehicle or perform operational control on the vehicle in response to detecting the range-extended relay attack.
In other features, the control module is configured to: determining a start time and an end time of the synchronous access word based on the initiator packet; and detecting a time difference based on the start time and the end time.
In other features, the control module is configured to: determining a start time and an end time for the synchronous access word relative to a first CW tone of the response packet based on the initiator packet; determining whether a start time and an end time of a synchronous access word of the response packet match the determined start time and end time; and detecting a time difference if the start time and the end time of the synchronous access word of the response packet do not match the determined start time and end time.
In other features, the control module is configured to: determining a first length of a synchronous access word of an initiator packet; comparing the first length to a second length of a synchronous access word of the response packet; and detecting an extended range type relay attack if a difference between the first length and the second length is greater than a predetermined amount.
In other features, the control module is configured to: determining a first length of a first CW tone of an initiator packet; comparing the first length to a second length of a first CW tone of the response packet; and detecting an extended range type relay attack if a difference between the first length and the second length is greater than a predetermined amount.
In other features, the first CW tone of the initiator packet is at an end of the initiator packet; and the first CW tone of the response packet is at the beginning of the response packet.
In other features, the initiator packet includes a second CW tone. The response packet includes a second CW tone.
In other features, the first CW tone of the initiator packet is at a beginning of the initiator packet. The second CW tone of the initiator packet is at the end of the initiator packet. The first CW tone of the response packet is at the beginning of the response packet. The second CW tone of the response packet is at the end of the response packet.
In other features, the initiator packet and the response packet have the same format.
In other features, the response packet indicates a phase difference amount between the second CW tone of the initiator packet and the first CW tone of the response packet. The first CW tone of the response packet has a phase relationship with a phase-locked loop of the responder.
In other features, the control module is configured to determine a phase difference between a first CW tone of the response packet and a second CW tone of the initiator packet. The second CW tone of the initiator packet is in phase relationship with a phase locked loop of the initiator. The first device and the second device are configured to determine a phase difference of the second frequency and a phase difference of the third frequency. The control module is configured to determine a distance between the devices based on (i) a phase difference between the first CW tone and the second CW tone, (ii) a phase difference for the second frequency, and (iii) a phase difference for the third frequency.
In other features, the control module is configured to compare a frequency, power level, bit, and amplitude of a portion of the received signal including the response packet to a frequency, power level, bit, and amplitude of a portion of the transmitted signal including the initiator packet, and determine whether an extended range relay attack has occurred based on the resulting difference.
In other features, a method for accessing a vehicle or providing operational control of a vehicle is provided. The method comprises the following steps: transmitting an initiator packet from the vehicle to the second network device via a first antenna module of the first network device, wherein the first antenna module comprises a plurality of polarized antennas, wherein the initiator packet comprises a synchronous access word and a first Continuous Wave (CW) tone, wherein one of the first network device and the second network device is implemented within the vehicle, and wherein the other of the first network device and the second network device is a portable access device, and wherein at any time at least one of the plurality of polarized antennas of the first antenna module is not cross-polarized with an antenna of the second network device; receiving a response packet from the second network device, the response packet including the synchronization access word and the first CW tone; determining that a timing difference between the initiator packet and the response packet is greater than a predetermined threshold; detecting, based on the timing difference being greater than a predetermined threshold, an extended range type relay attack performed by the attack apparatus in order to obtain at least one of access to the vehicle or operation control over the vehicle; and at least one of preventing access to the vehicle or performing operational control on the vehicle in response to detecting the range-extended relay attack.
In other features, the method further comprises: determining a start time and an end time of the synchronous access word based on the initiator packet; and detecting a time difference based on the start time and the end time.
In other features, the method further comprises: determining a start time and an end time of the synchronous access word relative to a first CW tone of the response packet based on the initiator packet; determining whether a start time and an end time of a synchronous access word of the response packet match the determined start time and end time; and detecting a time difference if the start time and the end time of the synchronous access word of the response packet do not match the determined start time and end time.
In other features, the first CW tone of the initiator packet is at an end of the initiator packet; and the first CW tone of the response packet is at the beginning of the response packet.
In other features, the initiator packet includes a second CW tone. The response packet includes a second CW tone. The first CW tone of the initiator packet is at the beginning of the initiator packet. The second CW tone of the initiator packet is at the end of the initiator packet. The first CW tone of the response packet is at the beginning of the response packet. The second CW tone of the response packet is at the end of the response packet.
In other features, the method further comprises: the round trip time of the initiator packet is determined based on the amount of phase delay. The response packet indicates an amount of phase delay between the first CW tone of the initiator packet and the first CW tone of the response packet.
In other features, a system for detecting a range-extended relay attack is provided. The system includes a transmitter, a receiver, and a control module. The transmitter is configured to transmit a radio frequency signal from one of the vehicle and the portable access device to the other of the vehicle and the portable access device. The receiver is configured to receive a response signal from one of the vehicle and the portable access device in response to the radio frequency signal. The control module is configured to: converting the response signal into an in-phase signal and a quadrature signal; detecting, based on the radio frequency signal, the in-phase signal and the quadrature signal, an extended range type relay attack performed by the attack apparatus for at least one of gaining access to the vehicle or controlling operation of the vehicle, wherein at least one of: (i) the first radio frequency signal is relayed from the vehicle to the portable access device via the attack device, or (ii) the first response signal is relayed from the portable access device to the vehicle via the attack device; and performing a countermeasure in response to detecting the range-extended relay attack.
In other features, the system further comprises an antenna module. The antenna module is implemented at one of the vehicle and the portable access device where the transmitter and the receiver are implemented. The antenna module includes a plurality of polarized antennas. At any instant in time, at least one of the plurality of polarized antennas of the antenna module is not cross-polarized with an antenna of the other of the vehicle and the portable access device.
In other features, the control module is implemented at the vehicle. In other features, the control module is implemented at the portable access device.
In other features, the control module is configured to: determining a phase difference based on the in-phase signal and the quadrature-phase signal; measuring the round trip time of the radio frequency signal based on the phase difference; and detecting the extended range type relay attack based on the round trip time.
In other features, the control module is configured to: sampling the in-phase signal and the quadrature signal; and determining a received bit based on the in-phase signal and the quadrature signal.
In other features, the control module is configured to: upsampling the received bits based on the in-phase signal and the quadrature signal; up-sampling the other signal; cross-correlating a result of up-sampling the received bits based on the in-phase signal and the quadrature-phase signal with a result of up-sampling the other signal; and determining a phase based on a result of the cross-correlation.
In other features, the another signal includes a reference bit pattern. The control module is configured to determine a sign of the differential arctangent signal and generate a reference bit pattern based on the sign. In other features, the another signal comprises a radio frequency signal filtered via a gaussian low pass filter.
In other features, a method for detecting a range-extended relay attack is provided. The method comprises the following steps: transmitting a radio frequency signal from one of the vehicle and the portable access device to the other of the vehicle and the portable access device via a transmitter; receiving, via a receiver, a response signal from one of the vehicle and the portable access device in response to the radio frequency signal; converting, via the control module, the response signal into an in-phase signal and a quadrature signal; detecting, via a control module, an extended range relay attack performed by an attack device for at least one of gaining access to or operational control over a vehicle based on a radio frequency signal, an in-phase signal, and a quadrature signal, wherein at least one of: (i) relaying the radio frequency signal from the vehicle to the portable access device via the attack device, or (ii) relaying the response signal from the portable access device to the vehicle via the attack device; and performing a countermeasure in response to detecting the range-extended relay attack.
In other features, the antenna module is implemented at one of a vehicle and a portable access device where the transmitter and the receiver are implemented. The antenna module includes a plurality of polarized antennas. At any instant in time, at least one of the plurality of polarized antennas of the antenna module is not cross-polarized with an antenna of the other of the vehicle and the portable access device.
In other features, the control module is implemented at the vehicle. In other features, the control module is implemented at the portable access device.
In other features, the method further comprises: determining a phase difference based on the in-phase signal and the quadrature-phase signal; measuring the round trip time of the radio frequency signal based on the phase difference; and detecting the extended range type relay attack based on the round trip time.
In other features, the method further comprises: sampling the in-phase signal and the quadrature signal; and determining a received bit based on the in-phase signal and the quadrature signal.
In other features, the method further comprises: up-sampling the received bits based on the in-phase signal and the quadrature signal; cross-correlating the result of up-sampling the received bits with the result of up-sampling the other signal; and determining a phase based on a result of the cross-correlation. In other features, the another signal includes a reference bit pattern. In other features, the another signal comprises a radio frequency signal filtered via a gaussian low pass filter.
Further areas of applicability of the present disclosure will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
Drawings
The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:
FIG. 1 is a side view of an object illustrating RF primarily higher power signals traveling along a bounce path (bounce path) due to cross polarization of the RF antenna;
FIG. 2 is a functional block diagram of an example of a vehicle access system including an access module, an RF antenna, and a portable access device, according to an embodiment of the present disclosure;
FIG. 3 is a functional block diagram of an example of a vehicle including the access module of FIG. 2, according to an embodiment of the present disclosure;
FIG. 4 is a functional block diagram of an example of the access module of FIG. 2, according to an embodiment of the present disclosure;
FIG. 5 is a functional block diagram of an example of an RF antenna module of a vehicle according to an embodiment of the present disclosure;
FIG. 6 is a functional block diagram of an example of a portable network device according to an embodiment of the present disclosure;
fig. 7 is an example of a polarization axis diagram illustrating a polarization diversity example arrangement according to an embodiment of the present disclosure;
figure 8 is an example of a polarization axis diagram illustrating another polarization diversity example arrangement in accordance with an embodiment of the present disclosure;
FIG. 9 is an example electric field diagram and polar plot illustrating an electric field pattern and null of a linear antenna;
fig. 10 is an exemplary voltage-electric field diagram for a linearly polarized antenna;
fig. 11A is a top perspective view of an example of at least a portion of a multi-axis polarized RF antenna assembly including a linearly polarized antenna and a circularly polarized antenna, in accordance with an embodiment of the present disclosure;
FIG. 11B is a bottom perspective view of the at least a portion of the multi-axis polarized RF antenna assembly of FIG. 11A;
fig. 12 is an exemplary polar plot of radiated power associated with the linearly polarized antenna of fig. 11A-11B;
fig. 13 is an exemplary polar plot of radiated power associated with the circularly polarized antenna of fig. 11A-11B;
fig. 14 is a functional block diagram of an example of RF circuitry and a portion of a portable access device according to an embodiment of the present disclosure;
fig. 15 is a block diagram of an example of a portion of a key fob having two linearly polarized slot antennas, a metallic garnish, and an emergency key according to an embodiment of the present disclosure;
fig. 16 is a block diagram of an example of a portion of the key fob of fig. 15 without a metal garnish and a spare key, but with an x-axis linearly polarized slot antenna and a y-axis linearly polarized slot antenna;
fig. 17 is an exemplary polar plot of radiated power associated with the x-axis linearly polarized slot antenna of the portion of the key fob of fig. 16;
Fig. 18 is an exemplary polar plot of radiated power associated with the y-axis linearly polarized slot antenna of the portion of the key fob of fig. 16;
fig. 19 is an example of a return loss versus frequency plot for the linearly polarized slot antenna of fig. 16;
fig. 20 is a block diagram of an example of a portion of the key fob of fig. 15 without a metal trim piece, but including a spare key;
fig. 21 is an exemplary polar plot of radiated power associated with the x-axis linearly polarized slot antenna of the portion of the key fob of fig. 20;
fig. 22 is an exemplary polar plot of radiated power associated with the y-axis linearly polarized slot antenna of the portion of the key fob of fig. 20;
fig. 23 is an example of a return loss versus frequency plot for the linearly polarized slot antenna of fig. 20;
fig. 24 is a block diagram of an example of a portion of the key fob of fig. 15 with a portion of a metal trim and a spare key;
fig. 25 is an exemplary polar plot of radiated power associated with the x-axis linearly polarized slot antenna of the portion of the key fob of fig. 24;
fig. 26 is an exemplary polar plot of radiated power associated with the y-axis linearly polarized slot antenna of the portion of the key fob of fig. 24;
fig. 27 is an example of a return loss versus frequency plot for the linearly polarized slot antenna of fig. 24;
Fig. 28 is an exemplary polar plot of radiated power associated with the x-axis linearly polarized slot antenna of the portion of the key fob of fig. 15;
fig. 29 is an exemplary polar plot of radiated power associated with the y-axis linearly polarized slot antenna of the portion of the key fob of fig. 15;
fig. 30 is an example of a return loss versus frequency plot for the linearly polarized slot antenna of fig. 15;
fig. 31 is a block diagram of an example of a portion of a key fob having a closed linearly polarized slot antenna, an open linearly polarized slot antenna, a metal garnish, and an emergency key according to an embodiment of the present disclosure;
fig. 32 is an exemplary polar plot of radiated power associated with the x-axis linearly polarized slot antenna of the portion of the key fob of fig. 31;
fig. 33 is an exemplary polar plot of radiated power associated with the y-axis linearly polarized slot antenna of the portion of the key fob of fig. 31;
fig. 34 is an example of a return loss versus frequency plot for the linearly polarized slot antenna of fig. 31;
fig. 35 illustrates a method of determining which antenna combination to use to exchange packets between an RF antenna module of a vehicle and a portable access device for round-trip time-of-flight measurements, in accordance with an embodiment of the present disclosure;
Fig. 36 illustrates another method of determining which antenna combination to use to exchange packets between an RF antenna module of a vehicle and a portable access device for round-trip time-of-flight measurements, in accordance with an embodiment of the present disclosure;
fig. 37 is a time-of-flight measurement diagram.
Figure 38 is a functional block diagram of an example BLE radio with a superheterodyne receiver and transmitter in accordance with an embodiment of the present disclosure;
FIG. 39 is an exemplary GFSK parameter definition diagram;
figure 40 is a functional block diagram of a system for transmitting BLE packets;
figure 41 shows an example preamble and access address for different types of BLE packets;
figure 42 is an example diagram of a BLE packet signal illustrating corresponding bits;
figure 43 is another example diagram of other BLE packet signals illustrating corresponding bits;
figure 44 is an overlay of the BLE packet signals of figure 44 in which one BLE packet signal has been shifted relative to the other BLE packet signal;
fig. 45 illustrates an example method of detecting a range-extended relay attack in accordance with an embodiment of the disclosure;
FIG. 46 is a functional block diagram of an example of a vehicle and portable access device including respective round trip time initiators and round trip time responders, in accordance with an embodiment of the present disclosure;
FIG. 47 is a functional block diagram of the vehicle and portable access device of FIG. 46 illustrating radio frequency signal transmission through a corresponding antenna;
FIG. 48 is a functional block diagram of the vehicle and portable access device of FIG. 46 under attack by a range-extended relay attack device;
figure 49 is a functional block diagram of two example BLE radios according to embodiments of the present disclosure;
FIG. 50 is a functional block diagram of an example location and distance determination system including a round trip time sniffer, according to an embodiment of the present disclosure;
FIG. 51 is a functional block diagram of an example location and distance determination system including multiple round trip time sniffers, according to an embodiment of the present disclosure;
fig. 52 is a functional block diagram of an example network device configured to perform tone switching for distance determination and attack detection in accordance with an embodiment of the present disclosure;
fig. 53 is a functional block diagram of an example position determination system including a tone sniffer in accordance with an embodiment of the present disclosure;
FIG. 54 illustrates a method of determining distances between an initiator and a responder and between a responder and a sniffer, in accordance with an embodiment of the present disclosure;
fig. 55 is a functional block diagram of an example passive tone switching and phase difference detection system in accordance with an embodiment of the present disclosure;
Fig. 56 is a functional block diagram of an example of an active tone swapping and phase difference detection system according to an embodiment of the present disclosure;
fig. 57 is a diagram of an example initiator and responder packet for RSSI and time-of-flight measurements, where the packet includes a Continuous Wave (CW) tone and a preamble, in accordance with an embodiment of the disclosure;
fig. 58 is a diagram of an example initiator and responder packet for RSSI and time-of-flight measurements, where the packet includes CW tones but does not include a preamble, in accordance with an embodiment of the disclosure;
fig. 59 is a diagram of an example initiator and responder packet for RSSI and time-of-flight measurements, where the packet has the same format and includes multiple CW tones but no preamble, in accordance with an embodiment of the disclosure;
FIG. 60 is a diagram illustrating an example initiator and response packet having the same format according to another embodiment of the present disclosure;
fig. 61 is a functional block diagram of an antenna path determination system for a network device having a corresponding antenna module according to another embodiment of the present disclosure;
figure 62 is an example radio model corresponding to the structure, function, and operation of the BLE radio of figure 38;
figure 63 illustrates a method of exchanging packets between RF antenna modules of a BLE radio to detect a range-extended relay attack in accordance with another embodiment of the present disclosure;
FIG. 64A is an exemplary plot of the signals from the sampling module, Gaussian LPF, and integrator, respectively, of the model of FIG. 62;
FIG. 64B is an exemplary plot of signals from the resampling module of the model of FIG. 62;
FIG. 64C is an exemplary plot of signals from the arctan module of the model of FIG. 62;
FIG. 64D is an exemplary graph showing the signal from the differentiator relative to the signal from the Gaussian LPF of the model of FIG. 62;
figure 65 illustrates a representation of different pairs of antenna shaft assemblies, each antenna shaft assembly including two linearly polarized antennas, in accordance with another embodiment of the present disclosure;
FIG. 66 illustrates a perspective view of a pair of antenna shaft assemblies having the same number of antennas, one antenna disposed in a metal container and the other antenna located outside of the metal container, in accordance with another embodiment of the present disclosure;
FIG. 67 illustrates a perspective view of another pair of antenna shaft assemblies having a different number of antennas, where one antenna is disposed in a metal container and the other antenna is located outside of the metal container, according to another embodiment of the present disclosure;
FIG. 68 is a diagram illustrating distance limiting while performing fast bit swapping, where the authenticator sequence may be cryptographically secure and known, independent of the authenticator sequence; and
Fig. 69 is a diagram illustrating preventing response bits from being issued prematurely while performing fast bit swapping, where the authenticator sequence may be cryptographically secure and dependent on the authenticator sequence.
FIG. 70 is a side view of multiple antennas illustrating angle of arrival;
FIG. 71 illustrates an AOA method including using a music algorithm according to the present disclosure;
FIG. 72 is an exemplary graph of covariance according to the present disclosure;
FIG. 73 is an exemplary graph of a feature vector and array manifold response according to the present disclosure;
FIG. 74 is another exemplary graph of a feature vector and array manifold response according to this disclosure;
FIG. 75 is an example music power spectrogram according to the present disclosure;
fig. 76 is a functional block diagram of an antenna selection system according to the present disclosure;
FIG. 77 illustrates an example reconstruction method according to this disclosure;
FIG. 78A is a top view of a vehicle illustrating an example placement of sensors according to the present disclosure;
FIG. 78B is a side view of the vehicle of FIG. 78A;
FIG. 78C is a rear view of the vehicle of FIG. 78A illustrating bounce reflections and corresponding paths of the transmitted signal detected at the sensor according to the present disclosure;
FIG. 79A is a top view of a vehicle illustrating another example placement of sensors according to the present disclosure;
Fig. 79B is a side view of the vehicle of fig. 79A. 79A; and
fig. 79C is a rear view of the vehicle of fig. 79A illustrating bounce reflections and corresponding paths of the transmitted signal detected at a sensor according to the present disclosure.
In the drawings, reference numbers may be reused to identify similar and/or identical elements.
Detailed Description
The RF device may measure distance by unmodulated carrier tone swapping. For example, in U.S. patent No.8,644,768B2, which is incorporated herein by reference, a system and method for distance measurement between two nodes of a radio network is provided that uses an unmodulated carrier tone swap.
The RF device may measure or constrain the distance by timing the round trip of the fast exchange of cryptographic security messages. For example, in "Distance-Bounding Protocols (Extended abstrates)" proposed by Brands and Chaum at the institute of cryptography and applications for advances (eurocypt' 93), which is also incorporated herein by reference, a sequence of rapid bit exchanges between a verifier and a prover is used. As shown in fig. 68, the prover sequence may be cryptographically secure and known, independent of the verifier sequence. As shown in fig. 69, the prover sequence may be cryptographically secure and dependent on the verifier sequence.
An RF device that measures Distance by round-trip timing may experience early discovery and subsequent attack as described in "assignments on Time-of-Flight Distance sounding Channels" by Hancke and Kuhn during the first wireless network security ACM conference (WiSec'08), which is also incorporated herein by reference. RF devices that measure range through unmodulated Carrier tone switching may be attacked by the signal delay flipping attack described in "On the Security of Carrier Phase-based Ranging" by Olafsdotter, Ranganathan, and Capkun, as set forth in IACR cryptography ephin architecture 2016, also incorporated herein by reference.
Although conventional PEPS systems allow for keyless entry and start of vehicles, conventional PEPS systems may be vulnerable to extended range relay attacks. An extended range relay attack may refer to an attacker using a relay device to detect, amplify, and relay signals between a key fob (or other intelligent portable network device) and a vehicle such that an access module of the vehicle operates as if the key fob had been in proximity to the vehicle and was in close proximity to the vehicle. For example, when an attacker touches the door handle of the vehicle with a hand and/or with a relay device, the access module may generate and send a LF wake-up signal. As a result, a valid relay device is detected and the access module sends an LF wake-up signal to the key fob, which is received at the relay device. The relay device receives, amplifies and forwards (or rebroadcasts) the LF wake-up signal to the actual key fob. For example, the key fob may be located in a residence and the vehicle may be parked outside or in front of the residence. The key fob may receive the amplified wake-up signal and generate a response signal and/or begin communicating over the RF link. The response signal and/or the RF communication signal is amplified and relayed between an antenna on the vehicle and one or more antennas of the key fob. This may be done via a relay device. As a result, the relay device is viewed by the access module as a key fob and the relay device "entices" the access module to operate as if the key fob were in the location of the relay device, which causes the access module to provide unauthorized access to the vehicle interior.
Additionally, as described further below, the antenna system of the current PEPS system may prevent the PEPS system from accurately estimating the distance between the key fob and the vehicle and accurately estimating the location of the key fob relative to the vehicle. The distance and location may be determined based on time-of-flight measurements. The time of flight and corresponding received signal strength are measured. The Received Signal Strength Indicator (RSSI) with the largest amplitude typically corresponds to the direct or shortest distance between the key fob and the vehicle. The time-of-flight measurement associated with the maximum RSSI is used to calculate the distance between the key fob and the vehicle.
Examples set forth herein include a combined LF and RF PEPS key fob that uses RF Round Trip Timing (RTT) measurements to prevent extended range relay station attacks. Other examples include RTT measurements, carrier phase based ranging, and a combination of RTT measurements and carrier phase based ranging in PEPS systems. These examples also set forth a number of other features, which will be further described below.
Fig. 1 shows an example of when cross-polarization of the antennas may result in inaccurate distance determination between a first RF antenna of a key fob and a second RF antenna of a vehicle. If the first RF antenna of the key fob is positioned relative to the second RF antenna of the vehicle such that the first RF antenna is cross-polarized with the second RF antenna, the determined distance corresponds to a bounce path rather than a direct path. For example, when the polarizations of the antennas are perpendicular to each other, the antennas are cross-polarized. An example of this is shown in fig. 1.
Fig. 1 shows an object 10 and polarization axes 12, 14 of the respective RF antennas. The antenna is a linearly polarized antenna. The first RF antenna has a first polarization axis 12 and is in a vehicle. The second RF antenna has a second polarization axis 14 and is in the key fob. Due to the relative positions of the first RF antenna, the second RF antenna, and the object 10, the RF signal 16 transmitted from the antennas may bounce off the object 10. The signal energy (or voltage) corresponding to the bounce path is greater than the signal energy (or voltage) corresponding to the direct path 18 between the antennas. This is due to the cross-polarization of the RF antenna. An access module that determines the distance between antennas based on the signal path having the greatest signal energy or voltage may erroneously determine the distance between antennas as the length of the bounce path 16 instead of the direct path 18.
Aligning the null (null) in a co-polarized antenna arrangement also results in a bounce path being used. This situation occurs when the first and second RF antennas are pointing in the same direction. The antenna may be positioned such that the wire extends longitudinally through the antenna. This is further described with respect to fig. 9-10.
Examples set forth herein include polarization diversity for RF signal transmission between an RF antenna of a vehicle and an RF antenna of a portable access device (e.g., key fob, mobile phone, wearable device, etc.). Additionally, examples include pseudo-random bidirectional data exchanges. Polarization diversity is provided to ensure that, at any one time, at least one transmit antenna has at least one polarization axis that is not cross-polarized but is slightly co-polarized with the polarization axis of at least one receive antenna, with no co-linear nulls co-polarized. As used herein, the phrase "at any time" refers to all times when corresponding devices are in communication with each other and/or all times when one or more signals are transmitted between devices and received by one or more devices. This helps to prevent extended range relay attacks in addition to allowing accurate range determination. The pseudo-random bi-directional data exchange described below also helps to prevent extended range relay attacks.
Example embodiments will now be described more fully with reference to the accompanying drawings.
FIG. 2 illustrates a vehicle access system 28 that functions as a PEPS system and a PAK system. The vehicle access system 28 includes a vehicle 30 and may include a key fob 32, a mobile phone 34, and/or other portable access devices, such as wearable devices, laptop computers, or other portable network devices. The portable access device may be, for example, a supportSuch as a smart phone, smart watch, wearable electronic device, key fob, tablet device, or other device associated with a user of the vehicle 30. The user may be an owner, driver, or passenger of the vehicle 30 and/or a technician directed to the vehicle 30.
The vehicle 30 includes an access module 36, an LF antenna module 38, and an RF antenna module 40. Access module 36 may wirelessly transmit LF signals to the portable network device via LF antenna module 38 and may wirelessly communicate with the portable computer via RF antenna module 40. The RF antenna module 40 provides polarization diversity between each antenna of the portable network device and the antenna of the RF antenna module 40. Polarization diversity, as described further below, provides a minimum number of polarization axes, combinations of polarization axes, and arrangements of polarization axes at the portable network device and vehicle 30 to ensure that at any one time at least one transmit antenna has at least one polarization axis that is not cross-polarized with the polarization axis of at least one receive antenna. In other words, at any instant in time, the at least one RF antenna of the vehicle has at least one polarization axis that is not cross-polarized with the polarization axis of the at least one RF antenna of each portable access device. Although a particular number of LF and RF antenna modules are shown, any number of LF and RF antenna modules may be used.
The LF antenna module 38 may be at various locations on the vehicle and transmit low frequency signals (e.g., 125kHz signals). Each LF antenna module includes an LF antenna and may include a control module and/or other circuitry for LF signaling. The RF antenna module 40 may also be located at various locations on the vehicle and transmit RF signals, such as Bluetooth Low Energy (BLE) signals, according to a BLE communication protocol. Alternatively, RF antenna module 40 may communicate according to other wireless communication protocols, such as wireless fidelity (Wi-Fi). An example of an antenna is shown in fig. 11 (refer to fig. 11A and 11B collectively).
In one embodiment, the RF antenna module 40 is located in the roof 46 of the vehicle 30 in order to improve signal coverage with respect to the vehicle and improve transmission and reception characteristics. As an example, each RF antenna module 40 may include a pair of RF antennas, one linearly polarized antenna, and one circularly polarized antenna. The number and location of the RF antenna modules may be preselected based on the size and shape of the vehicle 30. In one embodiment, two RF antenna modules are included and spaced apart from each other, as shown in fig. 2, such that the corresponding electric fields overlap each other, extending around and past the periphery of the vehicle in a 360 ° pattern. The electric field provides a resultant electric field as shown in fig. 1, represented by the dashed circle 48. The dashed circle provides the overall shape of a "rectangle-like". In larger vehicles, more antenna modules 40 may be added to make the shape more "rectangular-like". In small vehicles, only one of the RF antenna modules 40 may be included.
Different numbers of antennas with different numbers of antenna polarizations may be utilized. Fig. 65-67 illustrate some other example antenna implementations. Fig. 65-67 include fewer antennas and antenna polarizations that are used to measure or limit distance when different sets of frequencies and/or RF channels are used to measure or constrain the distance and/or reflections of metal in a vehicle. This is done to create virtual polarization diversity. Due to cross-polarization and/or null alignment, the antenna system can tolerate a certain erroneous measurement rate. In fig. 65-67, 7100A-J refers to antenna shaft assemblies, 7100A-71001 refers to antenna shaft assemblies having two polarization axes, and 7100J refers to antenna shaft assemblies having one polarization axis. Reference numerals 7101A-71011 and 7102A-7102I refer to the polarized antenna axes of the two polarized antenna axis assemblies. Reference numeral 7101J refers to the single polarization axis of 7100J. Reference numerals 7103AB, 7103CD, 7103EF, 7103GH, and 7103JI refer to the RF path between a pair of antenna assemblies. There are many RF paths between the antenna axes, some with more link margin, some with less link margin, some with more phase rotation time delay, and some with less phase rotation time delay. The different round trip timing and unmodulated carrier tone switching ranging algorithms disclosed, described, and/or referenced herein have the ability to find or measure shorter paths with link margins of several decibels (dB) up or down compared to the highest link margin path (which may not be the shortest). The more round-trip timing or tone-swapping measurements made across more frequencies (or channels), the more mathematically complex the algorithm and the more time-consuming the timing, the smaller the link margin in the shorter indirect path found.
The additional antenna axis provides polarization diversity in the RF path between the antenna axis components, which provides path diversity. Reference 7200 refers to a simplified representation of an open three-sided metal box and/or vehicle body for RF radio waves in the gigahertz or gigahertz range. Reference 7201 refers to a simplified representation of a metal plate and/or a box lid and/or a roof of a vehicle for RF radio waves in the gigahertz or gigahertz range. Fig. 66 and 67 can also be viewed upside down, where 7200 is a simplified representation of the open concave shape of the roof of the vehicle and 7201 is a simplified representation of the floor of the vehicle.
The RF connection between 7100A and 7100B along RF path 7101AB is strong because both pairs of antenna axes between the antenna axis assemblies are co-polarized. For multiple pairs of two-axis antennas with arbitrary orientation, even if the area of co-polarization is wide, perhaps 5 degrees out of 90 degrees rotation, the link margin may be 6dB higher than the middle link margin, which is rare. This is because three angular rotations are required to steer an arbitrarily oriented pair of antenna axis components into this configuration, and because the antenna axes are symmetric every 90 degrees, this happens arbitrarily, approximately at portions of time (5/90) × (5/90) × (5/90) or 1.71E-4. The RF connection between 7100C and 7100D along RF path 7101CD is not as strong as 7101AB, but it is good because no antenna paths are co-polarized or cross-polarized and the nulls are misaligned. The RF connection between 7100E and 7100F along RF path 7101EF is weak because each antenna path between the respective antenna axes is either cross-polarized or involves a null of at least one antenna. This is rare because again 3 angular rotations are required to steer a pair of arbitrarily oriented antenna axis pairs into this configuration. Additionally, for an arbitrarily oriented antenna pair of a two-axis antenna pair, such as a null region with 5 degrees cross polarization and alignment, such as 20dB below the link margin or pow2dB (sin (pi) 5/180) a2, three angular rotations are required to steer the arbitrarily oriented antenna pair into this configuration, and the antenna axes are symmetric every 90 degrees, which occurs at portions of time (5/90) × (5/90) (5/90) or 1.71E-4.
Referring to fig. 7-8, it is apparent that with three mostly orthogonal polarization axes on one side and two mostly orthogonal polarization axes on the other side, nulls are not aligned when cross-polarized. With three mostly orthogonal polarization axes on one side and one polarization axis on the other, the null can be aligned via two rotations so that it happens arbitrarily.
Overall, the more antenna axes on each side of the connection, the lower the likelihood of a direct path with low link margin. Preventing or reducing the possibility of a direct path with a low link margin is beneficial because round trip timing ranging and unmodulated carrier tone switching ranging tend to measure the direct path, which has a greater link margin than the reflected path. Conversely, the lower the link margin in the direct path relative to the reflected path, the greater the likelihood that the ranging technique will measure the distance along the reflected path.
In FIG. 66, when: the size of the metal box is reasonable relative to the decision constraint of the measured range; the variation of the distance is measured based on different reflection paths inside the metal box; and one side of the ranging connection is placed in a metal box, so planning on several direct paths may reduce the number of polarization axes needed to obtain a reasonable measurement. When one of the antenna axes of 7100G is oriented such that the null points along the strongest and/or shortest reflected path toward 7100H, the other antenna axis of 7100G finds a bounce path with strong link margin to one of the antenna axes 7101H or 7102H. This is particularly true when averaging across multiple channels, such as 37 data channels within a BLE data link. Some of the channel and antenna axis path combinations may fade quickly due to multipath, but not most combinations. In any arbitrary orientation of antenna axis pair 7100G, the link margin to antenna axis pair 7100H is about the same and the distance measured along the 7103IJ reflection path is about the same. The manner in which the reflected path 7103GH bounces off the roof 7201 or sidewalls of 7200 will vary, but the overall path variation will be limited by the size and location of the 7200 and 7201 components. When 7100G is raised to a height where a direct path exists, this path change limit will change, which will shorten the measured distance by eliminating the reflection of path 7103 GH. The range measured between 7100G and 7100H along the reflected path or shorter direct path will set a comparison constraint indicating that 7100G (which may be part of the portable device) is within a distance threshold of 7100H. 7100H may be part of PEPS module 211 or PAKM module 212. These ranging measurements between a pair of 7100 modules may be obtained and compared to make them less than the constraint. The results of the measurements, distances, and/or comparisons may be used as part of an if-then-else comparison in a software decision tree to indicate that the portable access device 400 is within an engagement region, an unlocking region, and/or a movement region of the vehicle.
Fig. 67 is similar to fig. 66 except that antenna shaft assembly 7100J includes a single polarized antenna shaft 7101J. In an embodiment, the antenna shaft assembly 7100J includes only single polarized antenna shafts. 7101J may be oriented such that the null is oriented along the strongest and/or shortest reflection path toward 7100H. In this case, the round trip timing and unmodulated carrier tone swapping technique will tend to measure distance along a path (not depicted) that is away from bin 7200 and then bounces back to that bin. Two rotations are required to orient an arbitrarily oriented antenna axis to this orientation, e.g., an aligned null region with 5 degrees wide, e.g., 20dB down for link margin or tow 2dB (sin (pi) 5/180 a2, because two angular rotations are required to steer an arbitrarily oriented antenna pair into this configuration, and because the antenna is symmetric every 90 degrees, this orientation occurs arbitrarily at either the (5/90) or 3E-3 portion of time, this configuration can also be used to make distance measurement measurements between a pair of 7100 modules and compare the measurements to make them less than constraint, in addition to the increased portion of time to measure to a completely different indirect path due to the higher power path reflected from a distant object, the results of the measurements, distances, and/or comparisons can be used as part of one or more "if-then-else" comparisons and software decision trees, to indicate that the portable access device 400 is within the approach area, unlock area, and/or movement area of the vehicle.
Different polarizations of the antennas can be used to create polarization diversity. Multiple polarized antennas (or antenna axes) create polarization diversity. A linear axis and another linear axis, a linear axis and two linear axes including a circularly polarized antenna, or three independent linear axes (linearly polarized antennas) are possible. Virtual polarization diversity occurs especially if there is metal in the vicinity.
The 7101H or 7101J antenna axis pairs may be placed lower in the metal box, which is the body of the vehicle, or higher in the metal box, which is the roof of the vehicle, to achieve these virtual antenna axis array effects.
Fig. 3 shows a vehicle 200 as an example of the vehicle 108 of fig. 1. The vehicle 200 includes a PAK system 202, the PAK system 202 including a vehicle control module 204, an infotainment module 206, and other control modules 208 (e.g., body control modules). The modules 204, 206, 208 may communicate with one another via a Controller Area Network (CAN) bus 209 and/or other vehicle interfaces (e.g., the vehicle interface 45 of fig. 2). The vehicle control module 204 may control operation of vehicle systems. The vehicle control module 204 may include the PEPS module 211, the PAK module 212, and the parameter adjustment module 213, as well as other modules, shown in FIG. 4. The vehicle control module 204 may also include one or more processors configured to execute instructions stored in a non-transitory computer-readable medium, such as memory 218, which may include Read Only Memory (ROM) and/or Random Access Memory (RAM).
The PEPS module 211 may perform PEPS operations to provide access to the vehicle interior and allow for vehicle startup and/or operation. The PAK module 212 operates in conjunction with the PEPS module 211 and performs PAK operations, as described herein. The PEPS module 211 may comprise the PAK module 212 or the modules 211, 212 may be implemented as a single module. The parameter adjustment module 213 may be used to adjust parameters of the vehicle 200.
The PAK system 202 may further include: a memory 218; a display 220; an audio system 221; and one or more transceivers including an LF antenna module 38 and an RF antenna module 40. The rf antenna module 40 may include and/or may be connected to rf circuitry 223. The PAK system 202 may further include: a telematics module 225; a sensor 226; and a navigation system 227 including a Global Positioning System (GPS) receiver 228. The RF circuitry 223 may be used to communicate with a mobile device (e.g., the mobile device 102 of FIG. 1), including transmitting at 2.4 gigahertz (GFIz)A signal. The RF circuitry 223 may include BLE radios, transmitters, receivers, and the like for transmitting and receiving RF signals.
The one or more transceivers 222 may include an RF transceiver that includes RF circuitry 223 and implements an access application having code for examining time-stamped data received and transmitted by RF antenna module 40. The access application can confirm that the RF antenna module, for example, received the correct data at the correct time. The access application may be stored in the memory 218 and implemented by the PEPS module 211 and/or the PAK module 212. Other example operations for accessing an application are described further below.
Accessing an application may be implementedA protocol stack configured to provide a channel map, an access identifier, a next channel, and a time for the next channel. The access application is configured to output a timing signal for time stamping of signals transmitted and received via the RF antenna module 40. The access application may obtain channel mapping information and timing information and share this information with other modules in the vehicle.
The telematics module 225 may communicate with the server via a cell tower station. This may include the sending of certificates, license information, and/or timing information including global clock timing information. The telematics module 225 is configured to generate location information and/or errors in the location information associated with the vehicle 200. The telematics module 225 may be implemented by a navigation system 227.
The sensors 226 may include sensors for PEPS and PAK operations, cameras, object detection sensors, temperature sensors, accelerometers, vehicle speed sensors, and/or other sensors. The sensor 226 may comprise a touch sensor to detect, for example, a person touching a door handle to initiate a process of waking up the portable access device. The sensors 226 may be connected to other control modules 208, such as a body control module, which may communicate with the LF and RF antenna circuits and/or modules disclosed herein. The GPS receiver 228 may provide speed and/or direction (or heading) of the vehicle and/or global clock timing information.
Memory 218 may store sensor data and/or parameters 230, credentials 232, connection information 234, timing information 236, tokens 237, keys 238, and applications 239. Applications 239 may include application programs executed by modules 38, 40, 204, 206, 208, 210, 211, 212, 223 and/or transceiver 222. By way of example, the applications may include an access application, a PEPS application, and/or a PAK application executed by the transceiver 222 and the modules 210, 211, and/or 212. Although the memory 218 and the vehicle control module 204 are shown as separate devices, the memory 218 and the vehicle control module 204 may be implemented as a single device. A single device may include one or more of the other devices shown in fig. 2.
The vehicle control module 204 may control operation of the engine 240, the converter/generator 242, the transmission 244, the window/door system 250, the lighting system 252, the seating system 254, the rearview mirror system 256, the braking system 258, the motor 260, and/or the steering system 262 based on parameters set by the modules 204, 206, 208, 210, 211, 212, 213. The vehicle control module 204 may perform PEPS and/or PAK operations, which may include setting some of the parameters. The PEPS and PAK operations may be based on signals received from the sensors 226 and/or the transceiver 222. The vehicle control module 204 may receive power from a power source 264, which may be provided to the engine 240, the converter/generator 242, the transmission 244, the window/door system 250, the lighting system 252, the seat system 254, the rearview mirror system 256, the braking system 258, the motor 260, and/or the steering system 262, among others. Some of the PEPS and PAK operations may include unlocking doors of the window/door system 250, enabling fuel and spark of the engine 240, starting the motor 260, powering any of the systems 250, 252, 254, 256, 258, 262, and/or performing other operations as further described herein.
The engine 240, converter/generator 242, transmission 244, window/door system 250, lighting system 252, seat system 254, rearview mirror system 256, braking system 258, motor 260, and/or steering system 262 may include actuators that are controlled by the vehicle control module 204 to, for example, adjust fuel, spark, air flow, steering wheel angle, throttle position, pedal position, door locks, window position, seat angle, and so forth. The control may be based on the outputs of the sensors 226, navigation system 227, GPS 228, and the above data and information stored in memory 218.
Fig. 4 shows the access module 210. The access module 210 includes a PEPS module 211, a PAK module 212, a parameter adjustment module 213, and may further include a link authentication module 300, a connection information distribution module 302, a timing control module 304, a sensor processing and location module 306, a data management module 308, and a security filtering module 310. The PAK module 212 may include an RTC 312 that maintains a local clock time.
The link authentication module 300 may authenticate the portable access device of fig. 2 and establish a secure communication link. For example, the link authentication module 300 may be configured to implement challenge-response authentication or other cryptographic verification algorithms in order to authenticate the portable access device.
The connection information distribution module 302 is configured to communicate with some of the sensors 226 of fig. 3 and provide the sensors with the communication information necessary to enable the sensors to find and then follow or eavesdrop on the secure communication link. This situation may occur once the sensor is synchronized with a communication gateway, which may be included in or implemented by one of the transceivers 222. As an example, the vehicle 200 and/or the PAK system 202 may include any number of sensors disposed at any location on the vehicle 200 for detecting and monitoring mobile devices. The connection information distribution module 302 is configured to obtain information corresponding to communication channels and channel switching parameters of the communication link and send the information to the sensors 226. In response to the sensor 226 receiving this information from the connectivity information distribution module 302 via the vehicle interface 45 and synchronizing the sensor 226 with the communications gateway, the sensor 226 may locate and follow or eavesdrop the communications link.
The timing control module 304 may: if the RTC and/or the current stored date is not handled by the PAK module 212, maintaining the RTC and/or the current stored date; propagating current timing information using a sensor; generating timestamps for incoming and outgoing messages, requests, signals, certificates, and/or other items; calculating the round trip time and the like. Round trip time may refer to the amount of time between the time a request is generated and/or sent and the time a response to the request is received. When link authentication module 300 performs challenge-response authentication, timing control module 304 may obtain timing information corresponding to the communication link. The timing control module 302 is also configured to provide timing information to the sensor 226 via the vehicle interface 209.
After link authentication is established, the data management module 308 collects the current location of the vehicle 108 from the telematics module 225 and shares the location with the portable access device. The portable access device optionally includes a GPS module and application software that, when executed, compares the estimated relative position of the portable access device with respect to the vehicle 108. Based on the estimated location of the portable access device relative to the vehicle 108, the portable access device may send a signal to one of the transceivers 222 requesting that the vehicle perform some action. As an example, the data management layer 308 is configured to obtain vehicle information obtained by any of the modules (e.g., location information obtained by the telematics module 225) and transmit the vehicle information to the portable access device.
The security filtering module 310 detects physical layer and protocol violations (isolation) and filters the data accordingly before providing the information to the sensor processing and location module 306. The security filtering module 310 marks the data as injected so that the sensor processing and localization module 306 can discard the data and issue an alert to the PEPS module 211. Data from the sensor processing and positioning module 306 is communicated to the PEPS module 211 so that the PEPS module 211 is configured to read vehicle status information from the sensors in order to detect a user's intent to access features and compare the location of the mobile device 102 to a set of locations that authorize certain vehicle features, such as unlocking the doors or trunk of the vehicle and/or starting the vehicle.
Fig. 5 is a functional block diagram of RF antenna module 40, which includes a control module 350 connected to a multi-axis polarized RF antenna assembly 352. Multi-axis polarized RF antenna assembly 352 may include linearly polarized antennas, other linearly polarized antennas, and/or circularly polarized antennas (e.g., right-hand circularly polarized antennas or left-hand circularly polarized antennas). An example of a multi-axis polarized RF antenna is shown in fig. 11. The control module 350 may include or may be part of a BLE communication chipset. Alternatively, the control module 350 may include or be part of a Wi-Fi or Wi-Fi direct communication chipset. Multi-axis polarized RF antenna assembly 352 may be included as part of RF antenna module 40 or may be located remotely from control module 350. Some or all of the operations of the control module 350 may be implemented by one or more of the modules 204, 210, 211, 212 of fig. 3.
The control module 350 (or one or more of the modules 204, 210, 211, 212 of fig. 3) may establish a secure communication connection with a portable access device (e.g., one of the portable access devices 32, 34 of fig. 2). For example, control module 350 may establish a secure communication connection using a BLE communication protocol, which may include transmitting and/or receiving timing and synchronization information. The timing and synchronization information may include information for the secure communication connection, such as timing of a next communication connection event, timing intervals between communication connection events, communication channels of the next communication connection event, channel maps, channel hopping intervals or offsets, communication delay information, communication jitter information, and the like. The control module 350 may detect (or "eavesdrop") packets sent by the portable access device to the vehicle control module 204 and measure signal information of signals received from the portable access device. The channel hop interval or offset may be used to calculate a channel for a subsequent communication connection event.
The control module 350 may measure the received signal strength of a signal received from the portable access device and generate a corresponding RSSI value. Additionally or alternatively, the control module 350 may make other measurements of the signal received from the portable access device, such as angle of arrival, time difference of arrival, and the like. The control module 350 may then send the measured information to the vehicle control module 204, and the vehicle control module 204 may then determine the location and/or distance of the portable access device relative to the vehicle 30 based on the measured information. The location and distance determinations may be based on similar information received from one or more other RF antenna modules and/or other sensors.
As an example, vehicle control module 204 may determine the location of the portable access device based on, for example, a pattern of RSSI values corresponding to signals received by RF antenna module 40 from the portable access device. A strong (or high) RSSI value indicates that the portable access device is close to the vehicle 30, while a weak (or low) RSSI value indicates that the portable access device is further from the vehicle 30. By analyzing the RSSI values, the control module 204 may determine the location and/or distance of the portable access device relative to the vehicle 30. Additionally or alternatively, angle-of-arrival, angle-of-departure, round trip timing, unmodulated carrier tone switching, or time difference of arrival measurements for signals transmitted between the portable access device and the control module 204 may also be used by the control module 204 or the portable access device to determine the location of the portable access device. Additionally or alternatively, RF antenna module 40 may determine a location and/or distance of the portable access device based on the measured information and communicate the location or distance to control module 204.
Based on the determined location of the portable access device relative to the vehicle 30 or distance relative to the vehicle 30, the modules 211, 212 of fig. 3 may then authorize and/or perform vehicle functions, such as unlocking the doors of the vehicle 30, unlocking the trunk of the vehicle 30, starting the vehicle 30, and/or allowing the vehicle 30 to be started. As another example, if the distance between the portable access device and the vehicle 30 is less than a first predetermined distance, the modules 211, 212 may turn on interior or exterior lights of the vehicle 30. If the distance between the portable access device and the vehicle 30 is less than the second predetermined distance, the modules 211, 212 may unlock doors or a trunk of the vehicle 30. If the portable access device is located within the vehicle 30, the modules 211, 212 may allow the vehicle 30 to be started.
Referring again to fig. 5, the control module 350 may include a physical layer (PHY) module 356, a Medium Access Control (MAC) module 358, a time synchronization module 360, and a channel map reconstruction module 362. PHY module 356 receives BLE signals via multi-axis polarized RF antenna assembly 352. Control module 350 may monitor the received BLE physical layer message and obtain measurements of physical properties of the corresponding signal, including, for example, received signal strength, using the channel map generated by channel map reconstruction module 362. The control module 350 may communicate with the control modules of the other RF antenna modules and/or modules 204, 210, 211, 212 via the vehicle interface 45 to determine time difference of arrival, time of arrival, angle of arrival, and/or other timing information. In one embodiment, the control module 350 comprises a portion of the RF circuitry 223 of FIG. 3.
The time synchronization module 360 is configured to accurately measure the time of receipt of a signal/message on the vehicle interface 45. The control module 350 may be based on channel mappingInformation as well as receive time and/or other timing information tunes PHY module 356 to a particular channel at a particular time. In addition, the control module may monitor the received PHY messages and data for compliance withPhysical layer specifications, such asSpecification version 5.1. The data, time stamp, and measured signal strength may be reported by the control module 350 to the control module 204 via the vehicle interface 45.
Fig. 6 illustrates an example portable access device 400, the example portable access device 400 being an example of one of the portable access devices 32, 34 of fig. 2. The portable access device 400 may include a control module 402, a user interface 404, a memory 406, a sensor 407, and a transceiver 408. The transceiver 408 may include a MAC module 410, a PHY module 412, and a plurality of linearly polarized antennas 414.
The control module 402 may include or may be part of a BLE communication chipset. Alternatively, the control module 402 may include or be part of a Wi-Fi or Wi-Fi direct communication chipset. The memory 406 may store application code that may be executed by the control module 402. The memory 406 may be a non-transitory computer-readable medium including Read Only Memory (ROM) and/or Random Access Memory (RAM).
The control module 402 communicates with the modules 204 and 350 of the vehicle and performs authentication and other operations as described further below. Control module 402 may transmit information about portable access device 400, such as location and/or velocity information obtained from one or more sensors 407 (e.g., global navigation satellite system (e.g., GPS) sensors, accelerometers, and/or angular velocity sensors). The user interface 404 may include a keyboard, touch screen, voice activated interface, and/or other user interfaces.
Fig. 7 shows a polarization axis diagram illustrating a polarization diversity example arrangement. In the example shown, two 3-axis antennas located within the vehicle communicate with a 2-axis antenna located in the portable access device (or mobile access network device). With sufficient antenna axes, this antenna topology can prevent cross-polarization situations between one of the 3-axis antennas and the 2-axis antenna. Additionally, with sufficient antenna axes, the system may be configured such that there is at least one pair of antennas with no nulls (or nulls not indicated) in the direct signal path. A heuristic measurement of RSSI may be performed on the Continuous Wave (CW) tone portion of the packet while measuring the round trip time and phase delay of the packet. This may be repeated over multiple frequencies. This may be done at the vehicle access module and/or the portable access device. Round trip timing and/or unmodulated carrier tone swapping may be used to ensure ranging. RSSI and varying (or incremental) phase for each frequency may be used.
Fig. 8 shows a polarization axis diagram illustrating another polarization diversity example arrangement. In the example shown, two single-axis antennas located within the vehicle communicate with a 3-axis antenna located in the portable access device (or mobile access network device). With sufficient antenna axes, this antenna topology may also prevent a cross-polarization condition between the single-axis antenna and one of the 3-axis antennas. Additionally, with sufficient antenna axes, the system may be configured such that there is at least one pair of antennas with no nulls (or nulls not indicated) in the direct signal path. A heuristic measurement of RSSI may be performed on the Continuous Wave (CW) tone portion of the packet while measuring the round trip time and phase delay of the packet. This may be repeated over multiple frequencies. This may be done at the vehicle access module and/or the portable access device. The round trip timing is used to ensure ranging. RSSI and varying (or incremental) phase for each frequency may be used. The example of fig. 7 may be more feasible than the example of fig. 8. This is because it may be difficult to integrate a 3-axis antenna in some portable access devices, such as key fobs.
Fig. 9 shows an electric field plot 900 and a polar plot 902 illustrating an electric field plot and nulls 906 of a linear antenna. The linear antenna is positioned along a vertical axis 908. The linear antenna has a radiation pattern in the shape of a "donut". The bounce path of the transmitted signal is measured when the nulls are aligned between the transmit and receive antennas (co-polarized antennas with nulls collinear or nearly collinear). The examples set forth herein prevent this from occurring between at least one transmit antenna and at least one receive antenna at any one time. An algorithm is set forth herein for determining which transmit and receive antennas are used at any one time to prevent the use of cross-polarized and/or co-polarized antennas. Once the appropriate antenna pair is selected, time-of-flight measurements are made to determine the distance between the transmitter and receiver and/or between the vehicle and the portable access device. Fig. 10 shows a voltage-electric field diagram 1000 of a linearly polarized antenna 1002.
Fig. 11A-11B illustrate at least a portion of an example of a multi-axis polarized RF antenna assembly 1100 including a linearly polarized antenna 1102 and a circularly polarized antenna 1104. The antennas 1102, 1104 are collocated. Linearly polarized antenna 1102 extends linearly away from circularly polarized antenna 1104 outward from the central axis of circularly polarized antenna 1104. The antennas 1102, 1104 may transmit 90 ° out of phase with each other. Linearly polarized antenna 1102 may include a conductive element (e.g., a straight line or a helical line) 1110 extending within a sleeve 1112. The circularly polarized antenna 1104 may be loop-shaped.
The linearly polarized antenna 1102 is a monopole antenna. The sleeve 1112 is formed of a dielectric material such as polytetrafluoroethylene. The antennas 1102, 1104 are both concentric with a disk insulator (or isolator) 1106 and a disk ground plane 1108. Ring insulator 1106 is stacked as a top layer on ground plane 1108 (or bottom layer). The circularly polarized antenna 1104 is disposed on the ground plane 1108 inside the recessed region 1114 of the insulator 1106. A recessed region 1114 of dielectric is disposed between the circularly polarized antenna 1104 and the ground plane 1108.
The circularly polarized antenna has two feed points 1120, 1122, while the linearly polarized antenna 1102 has a single feed point 1124. RF signals are transmitted and/or received via feed points 1120, 1122, 1124. RF signals are transmitted between the antennas 1102, 1104 and the RF circuitry 1114 via coaxial cables. The coaxial cable includes inner conductors 1130, 1132, 1134 and an external ground shield (not shown). The ground shield is connected to the ground plane 1108. Wires 1130, 1132, 1134 are connected to feed points 1120, 1122, 1124.
During transmission, a signal or voltage is provided across the ground plane 1108 and the conductive element 1110 via a feed point 1124, which feed point 1124 is connected to the conductive element 1110 and the ground plane 1108 via another conductive element 1140. RF signal(s) or voltage(s) are also applied across the ground plane 1108 and feed points 1120, 1122 of the circularly polarized antenna 1104. The feed points 1120, 1122 are located on the surface of the antenna 1104 with a 90 ° offset and are 90 ° out of phase with each other. The 90 electrical phase shift combined with the 90 geometric phase shift causes the circularly polarized antenna 1104 to radiate a circularly polarized signal. The feed points 1120, 1122 are connected from the ground plane 1108 through the dielectric 1106 to the circularly polarized antenna 1104. The aperture 1142 in the center of the ground plane 1108 and the aperture 1144 in the center of the circularly polarized antenna 1104 are large enough to allow the linearly polarized antenna 1102 to radiate without shorting to the ground plane 1108.
The antennas 1102, 1104 may be formed of a conductive material, while the circular isolator 1106 may be formed of a non-conductive (or electrically insulating) material. In one embodiment, linearly polarized antenna 1102 may be implemented as a straight line, with sleeve 1112 formed of Polytetrafluoroethylene (PTFE) and conductive element 1110 formed of copper. In another embodiment, linearly polarized antenna 1102 is implemented as a helix, wherein the wire is wrapped around a cylindrical object formed from PTFE. Fig. 12 shows a polar plot 1200 of radiated power associated with the linearly polarized antenna 1102 of fig. 11. Fig. 13 illustrates a polar plot of radiated power associated with the circularly polarized antenna 1104 of fig. 12. The antennas 1102, 1104 may be connected to RF circuitry 1114, such as one of the RF circuitry 223 of fig. 3, and may be configured to be installed in a roof of a vehicle. The antennas 1102, 1104 may be used for time-of-flight measurements between the vehicle and the portable access device, while other LF antennas in the vehicle may be used for authentication of the portable access device.
Although the antenna assembly is described primarily as having a circularly polarized antenna and a linearly polarized antenna, which may be arranged, for example, in the roof of a vehicle, two linearly polarized antennas may alternatively be used. This applies for each of the examples disclosed herein. The two linearly polarized antennas may be located deeper in the vehicle, such as in the floor, dashboard, or center console of the vehicle.
Fig. 14 shows a first RF circuit 1400, a second RF circuit 1401, and a portion 1403 of a portable access device (e.g., one of the portable access devices described above). Although a certain number of RF circuits are shown, any number of RF circuits may be included and may be in communication with the portable access device. The first RF circuit 1400 includes a serial transmit module 1402, an RF transceiver module 1404, a switch 1406, a splitter 1408, a single-axis polarized (or monopole) antenna 1410, a delay module 1412, and a circularly polarized antenna assembly 1414. Antennas 1410, 1414 may be implemented as multi-axial polarized RF antenna assemblies of fig. 11. Although the RF circuits are shown as having single-axis antennas and circularly polarized antennas, respectively, to provide 3 polarization axes, the RF circuits may include only two single-axis polarized antennas, respectively. Many permutations of linearly and circularly polarized antenna axes are possible to achieve polarization diversity in the module, thereby preventing co-linear alignment of cross-polarizations and/or nulls. If the RF circuitry includes two single-axis antennas, the portable access device includes a three-axis antenna or three single-axis antennas that are orthogonal with respect to each other to correspond to the x, y, and z axes.
The serial transmission module 1402 may communicate with one or more vehicle modules (e.g., the vehicle control modules or access modules disclosed above) via a serial bus according to a Serial Peripheral Interconnect (SPI) protocol. Discrete signals (or general purpose I/O signals) may be sent between the modules 1402, 1404 and between the RF transceiver module 1404 and the switch 1406. The RF transceiver module 1404 may communicate with the PEPS module 211 (of fig. 3). The switch 1406 switches between the antennas 1410, 1414. Separator 1408 may separate individual signals received from RF transceiver module 1404 and provide signals to antenna 1410 and antenna 1414 and/or combine signals received from antenna 1410 and antenna 1414. Separator 1408 can be a 90 ° separator and separates a single signal into two 90 ° out of phase signals and provides the signals to two feed points (e.g., feed points 1120, 1122 of fig. 11) on the circularly polarized antenna. The splitter 1408 can provide signals to the antenna 1414 or receive signals from the antenna 1414 via a delay module 1412.
The second RF circuit 1401 comprises a switch 1420, a splitter 1422, a single-axis polarized (or monopole) antenna 1424, a delay module 1426 and a circularly polarized antenna 1428. Antennas 1424, 1428 may be implemented as multi-axial polarized RF antenna assemblies of fig. 11. Devices 1420, 1422, 1424, 1426, 1428 may operate similarly to devices 1406, 1408, 1410, 1412, 1414. The switch 1420 may communicate with the RF transceiver module 1404. Switch 1406 may also connect separator 1408, single-axis polarized antenna 1410, and/or switch 1420 to RF transceiver module 1404. The switch 1420 may connect the single axis polarized antenna 1424 or the splitter to the switch 1406 or the RF transceiver module 1404.
RF signals are transmitted between (i) antennas 1410, 1414, 1424, 1428 and (ii) antennas 1438, 1440. By way of example, antennas 1410, 1424 may be associated with the z-axis, while antennas 1414, 1428 may be associated with the x-axis and y-axis, respectively. The antennas 1438, 1440 may be, for example, slot antennas associated with the x-axis and the y-axis, respectively. As described above, the 3-axis LF antenna 1430 may communicate with an LF antenna on a corresponding vehicle. The LF antennas may be used for downlink wake-up purposes. The RF antenna may be used for authentication and communication.
Fig. 15 shows a portion 1500 of a key fob having two linearly polarized slot antennas 1502, 1504, a metal trim 1506 and a spare key 1508. The metal in the key fob can short out the field that would otherwise be stable along the long dimension (or Y dimension) of the key fob. As a result, it can be difficult to design a high efficiency radiator having a structure that would otherwise include a properly operating antenna. Antenna 1502 is an x-axis linearly polarized slot antenna. Antenna 1504 is a y-axis linearly polarized slot antenna. The metal trim 1506 may be a cast decorative trim. The key fob may also include an LF coil antenna 1510, a processor (not shown), a battery 1512, and a metal plate (or conductive film) 1514. The RF signal is provided to the metal plate 1514 and the openings of the slot antennas 1502, 1504 to radiate electromagnetic waves.
Fig. 16 shows the portion 1600 of the key fob of fig. 15, but without the metal trim 1506 and spare key 1508. Portion 1600 includes an x-axis linearly polarized slot antenna 1502 and a y-axis linearly polarized slot antenna 1504. Removal of the metal trim 1506 and spare key 1508 supports radiation from the slot antenna. Although this configuration is configured to work with nearby metal (such as a metal garnish and an emergency key), the views of fig. 17 and 18 are shown, which are tilted from the views when the metal garnish and the emergency key are included. Fig. 17 shows a polar plot of radiated power associated with the x-axis linearly polarized slot antenna 1502 of the portion 1600 of the key fob of fig. 16. Fig. 18 shows an example polar plot of radiated power associated with the y-axis linearly polarized slot antenna 1504 of the portion 1600 of the key fob of fig. 17. Fig. 19 shows a return loss (in decibels (dB)) versus frequency plot for the linearly polarized slot antennas 1502, 1504 of fig. 16, where curve S1,1 is the reflected power for the first port or antenna 1502 of the first radio (or transmitter) and S2,2 is the reflected power for the second port or antenna 1504 of the second radio (or transmitter). The structure of the key fob may be provided to provide S1,1 and S2,2 graphs in which the "dip" or minimum return loss for the S1,1 and S2,2 curves are at the same frequency as each other or within a predetermined range to provide improved performance.
Return loss is a way to measure the extent to which an antenna converts a voltage on a terminal of the antenna to an electric field in space or the extent to which an antenna converts an electric field in space to a voltage on a terminal. Return loss is a decibel measure of how much power is reflected on a terminal. For example, if the return loss is 0dB, all power is reflected and no power is transmitted on the terminals. As another example, a return loss of-10 dB means that approximately 10% of the power is reflected and 90% of the power is transmitted. When the return loss plot includes a curve that is notched to a reasonable level at the operating frequency (e.g., -6dB), then the corresponding antenna works well. If the return loss is notched to-10 dB, the antenna is considered to be a well-functioning antenna. The return loss is measured as an S parameter. S1,1 is the return loss of port 1. S2,2 is the return loss of port 2.
Fig. 20 shows a portion 2000 of the key fob of fig. 15 without the metal trim 1506 but including a spare key 1508. Fig. 21 shows a polar plot of radiated power associated with the x-axis linearly polarized slot antenna 1502 of the portion 2000 of the key fob of fig. 20. Fig. 22 shows a polar plot of radiated power associated with the y-axis linearly polarized slot antenna 1504 of the portion 2000 of the key fob of fig. 20. The addition of a spare key may have a negative effect on the y-polarization but is acceptable for operation. Fig. 23 shows a return loss versus frequency plot for the linearly polarized slot antennas 1502, 1504 of fig. 20, where S1,1 is for antenna 1502 and S2,2 is for antenna 1504.
Fig. 24 shows a portion 2400 of the key fob of fig. 15 with a portion of a metal trim 2402 and a spare key 1508. The addition of a metal trim 2402 near the spare key 1508 may negatively impact operation, as shown by the graphs and curves in fig. 25-27. Fig. 25 shows a polar plot of radiated power associated with an x-axis linearly polarized slot antenna 1502 of the portion 2400 of the key fob of fig. 24. Fig. 26 shows a polar plot of radiated power associated with the y-axis linearly polarized slot antenna 1504 of the portion of the key fob of fig. 24. Fig. 27 shows a return loss versus frequency plot for the linearly polarized slot antenna of fig. 24, where S1,1 is for antenna 1502 and S2,2 is for antenna 1504. Fig. 19, 23 and 27 show that the antenna works well in the frequency range of interest (e.g., 2.4-2.8 GHz).
Referring to portion 1500 of fig. 15, with the presence of the entire metal trim piece 1506, the operation of the antenna is further negatively affected, as shown by the graphs and curves of fig. 28-30. Fig. 28 shows a polar plot of radiated power associated with an x-axis linearly polarized slot antenna 1502 of the section 1500. Fig. 29 shows a polar plot of radiated power associated with the y-axis linearly polarized slot antenna 1504 of the section 1500. Fig. 30 shows a return loss versus frequency plot for linearly polarized slot antennas 1502, 1504, where S1,1 is for antenna 1502 and S2,2 is for antenna 1504.
Since each of the antennas 1502, 1504 has an open end, the y-axis linearly polarized slot antennas 1502, 1504 are open slot antennas. Fig. 31 shows portion 3100 of a key fob having an open linearly polarized slot antenna 3102, a closed linearly polarized slot antenna 3104, a metal trim 3106, and an emergency key 3108. Fig. 32 shows a polar plot of radiated power associated with the x-axis linearly polarized slot antenna 3102 of portion 3100. Fig. 33 shows a polar plot of radiated power associated with the y-axis linearly polarized slot antenna 3104 of portion 3100. Fig. 34 shows a return loss versus frequency diagram for the linearly polarized slot antennas 3102, 3104 of fig. 31. Fig. 34 shows that the antenna measured at port S2,2 is not working well.
When the portable access device has multiple orthogonal antennas as described above, the portable access device is larger than the corresponding physical metal key, and the portable access device is larger than the palm, providing improved round trip time performance for removal of the decorated metal trim. The improved round trip time performance improves the accuracy of the distance determination.
The systems disclosed herein may be operated using various methods described herein. Several example methods of determining which antenna combination to use are illustrated in fig. 35 and 36. Fig. 35 and 36 illustrate a method of determining which antenna combination to use for round-trip time-of-flight measurements to exchange packets between the vehicle's RF antenna module (or RF circuitry) and the portable access device. Fig. 35 and 37 present the method from the perspective of the initiator of the round-trip time-of-flight measurement. In one embodiment, this is a vehicle. In another embodiment, this is a portable access device. The reflector/responder will perform the explicit steps corresponding to the initiator step in the process. The round-trip time-of-flight measurements may be used to thwart extended range relay attacks, as described further below. Fig. 35 illustrates a method of switching antennas between packets. Fig. 36 illustrates a method of switching antennas during transmission of packet and/or Continuous Wave (CW) tones.
Although the following operations are described primarily with respect to the implementations of fig. 2-6, 11, and 14, these operations may be readily modified to apply to other implementations of the present disclosure. This operation may be performed iteratively.
The method may begin at 3500. The following operations may be performed generally simultaneously by the control module 402 in the portable access device 400 and the modules located on the vehicle (e.g., by the access module 210, the PEPS module 211, and/or the PAK module 212 of fig. 4). There are a number of ways in which the frequency and antenna combinations that can be selected can be sampled to subsequently identify the best frequency (or channel) and antenna axis. Optionally, at 3501, the module negotiates an initial frequency (or channel) and antenna combination to use for frequency and antenna sounding. This step may be based on a priori protocols, negotiated between modules based on a posteriori data, and/or commanded by the modules based on a posteriori data. At 3502, a frequency (or channel) is selected to transmit the first (or next) packet.
At 3504, an antenna pair is selected at which to transmit and receive the packet. Such as two of the antennas of the RF circuitry of the vehicle of fig. 11. At 3506, the packet is transmitted from the first (or transmit) antenna to the portable access device at the selected frequency. The portable access device measures the RSSI of the transmission and sends the packet back as the first RSSI to the second (or receiving) antenna in the selected antenna pair.
At 3508, the second antenna receives the packet and/or the response to the transmission of the packet and the first RSSI. At 3512, a second RSSI is measured for a second transmission of the packet. At 3514, the first RSSI and the second RSSI are stored in memory in association with the packet, the selected frequency, and the selected antenna pair.
At 3516, if another pair of antennas is to be selected, then operation 3504 is performed, otherwise operation 3518 is performed. This allows for cycling through each antenna pair permutation for each selected frequency. The antenna pair permutation may be cycled through in a pseudo-random and/or predetermined order.
At 3518, if another frequency (or channel) is to be selected, then operation 3502 is performed, otherwise operation 3520 is performed. This allows cycling through each frequency (or channel). This allows the RSSI of each frequency (or channel) to be determined. Multipath fast fading may result in some frequencies having lower power levels (or RSSI values). As an example, the frequencies of the 37 BLE data channels may be cycled through in a pseudo-random and/or predefined order to determine the best frequency and/or channel and best antenna pair for transmission of other packets.
Optionally, at 3519, after cycling through a set of predetermined, negotiated, and/or agreed upon frequency and antenna axis pairs, the algorithm may cause the nodes (control modules) to optionally exchange antenna and/or channel RSSI results. Due to the reciprocity of the RF channel, the module may use heuristics that select the antenna axis used by the module without sharing the antenna RSSI measurements taken by the module. Due to the reciprocity of RF channels, a module may use heuristics to select a channel (frequency) without results from other channels, but a module may use an algorithm that selects a channel based on results from a channel. In this case, the algorithm and system are more immune to interference from other transmitters in the vicinity.
At 3520, after cycling through a predetermined number of frequency and antenna pairs, the antenna axis combination and/or frequency (channel) with the best RSSI is selected for transmitting the remaining packets. The best is the antenna axis combination with the highest RSSI. For frequencies (or channels), the combination of antenna axes with no low RSSI and/or no high RSSI is optimal. At 3522, identifiers of antenna pairs and/or frequencies (channels) that may be selected may be encrypted. At 3524, the encrypted selected antenna axis pair and/or frequency (channel) may be transmitted to another node. At 3526, packets are transmitted and responses are received using the selected frequency (channel) and antenna pair. The method may end at 3528.
Although the following operations of fig. 36 are described primarily with respect to the implementations of fig. 2-6, 11, and 14, these operations may be readily modified to apply to other implementations of the present disclosure. These operations may be performed iteratively.
The method may begin at 3700. The following operations may be performed generally simultaneously by the control module 402 in the portable access device 400 and the modules located on the vehicle (e.g., by the PEPS module 211 and/or the PAK module 212 of fig. 4). A number of different techniques may be used to select the sampled frequency and antenna combination to identify the best frequency (or channel) and antenna axis. Optionally, in 3701, the module negotiates an initial frequency (or channel) and antenna combination to be used in frequency and antenna sounding. This step may be based on a priori protocols, negotiated between modules based on a posteriori data, or commanded by the modules based on a posteriori data. At 3702, the frequency (or channel) to transmit the first (or next) packet is selected.
At 3704, an antenna pair to transmit and receive the packet is selected. Such as two of the antennas of the RF circuitry of the vehicle of fig. 11. At 3706, a packet is transmitted from a first (or transmit) antenna to the portable access device at a selected frequency. With pauses (dwell) during the CW tone portion of the packet, the vehicle switches between a set of negotiated antenna axes. The portable access device switches between a set of negotiated antenna axes with a dwell within each of the vehicle antenna axis "switch" and "dwell", measures the RSSI of the transmit and receive antenna axis arrangements during that reception for the period within the CW tone, and transmits the packet and the first set of measured RSSI back to the vehicle, and then switches between the set of negotiated antenna axes with a dwell during the CW tone portion of the antenna pair selected.
At 3708, the vehicle receives the packet and/or a response to the transmission of the packet and the first set of RSSIs. At 3712, a second RSSI is measured for a second transmission of the packet. At 3714, the first RSSI and the second RSSI are stored in memory in association with the packet, the selected frequency, and the selected antenna pair.
At 3716, if another packet is to be sent, then operation 3718 is performed, otherwise operation 3726 is performed. At 3718, if another antenna pair is to be selected, then operation 3720 is performed, otherwise operation 3724 is performed. This allows for cycling through each antenna pair permutation for each selected frequency. The antenna pair permutation may be cycled through in a pseudo-random and/or predetermined order.
At 3720, the previous transmit antenna in the previously selected antenna pair is used to begin the first transmission of the next packet.
At 3722, switching occurs between the previous antenna pair and the next selected antenna pair. This may occur during the CW tone of the packet currently being transmitted or during another portion of the packet currently being transmitted such that the remainder of the packet is transmitted via the transmit antenna of the next selected antenna pair. Operation 3708 may be performed after operation 3722.
At 3724, if another frequency (or channel) is to be fleed, then operation 3704 is performed, otherwise operation 3718 is performed. This allows cycling through each frequency (or channel). This allows the RSSI of each of the determined frequencies (or channels) to be determined. Multipath fast fading may result in some frequencies having lower power levels (or RSSI values). As an example, the frequencies of the 37 BLE data channels may be cycled through in a pseudo-random and/or predefined order to determine the best frequency and/or channel and best antenna pair for transmission of other packets. At 3725, the antenna and RSSI result values may be exchanged as described above at 3519.
At 3726, after cycling through a predetermined number of frequency and antenna pairs, the antenna combination and frequency and/or channel with the best RSSI is selected for transmitting the remaining packets.
At 3728, the identifier of the selected antenna pair may be encrypted. At 3730, each remaining packet may be encapsulated as, or modified to include, an encrypted identifier. At 3732, the encapsulated or modified packet is transmitted using the selected frequency, channel, and antenna pair, and a response is received. The method may end at 3734.
In the above method, the packet transmitted to determine the best frequency, channel and antenna pair may be discarded. The dropped packets are used only to measure RSSI values. In another embodiment, CW tones are included at the end of the packet and antenna switching occurs during these tones. In another embodiment, a predetermined time period (e.g., 4ps) is allocated for each antenna permutation, CW tones are included at the end of the packet, and the antenna pair with the best RSSI (or power value) is selected. The selected frequency, channel, and/or antenna pair may be changed if another nearby network device is transmitting and/or receiving data within the same frequency range. In an embodiment, the manner in which the frequency is selected during the methods of fig. 35 and 36 may be known and may be shared between the access module of the vehicle and the portable access device.
Fig. 37 shows a time-of-flight measurement plot 3800 that includes an initiating and measuring device 3802 and a reflecting (or responding) device 3804. The initiating and measuring device 3802 sends a radio message (e.g., a packet) to the reflecting device 3804, and the reflecting device 3804 then responds and resends the radio message back to the initiating and measuring device 3802. The time of flight (or the total time of transmission and reception of these signals) is equal to (T)2-T1)、(T3-T2) And (T)4-T3) And (d) wherein: t is2-T1Is the amount of time that the radio message travels from the initiating and measuring device 3802 to the reflecting device 3804; t is3-T2Is the amount of time that the reflecting device 3804 responds; t is4-T3Is the amount of time that the radio message travels from the reflecting device 3804 to the initiating and measuring device 3802. Example average time-of-flight and distance calculations may be performed according to equations 1-4, where distance refers to the distance between the initiating and measuring device 3802 and the reflecting device 3804.
Mean time of flight [ (total time) - (response time) ]/2 (1)
Mean time of flight [ [ (T)4-T1)+(T3-T2)]/2 (2)
Distance, speed, time (3)
Distance ═ c [ (T)4-T1)+(T3-T2)]/2 (4)
When the timer is used to respond to the time T3-T2At timing, the amount of timing information may be reduced to adjust the tuning information measured and associated with the response time. If the initiator does not know the amount of time, The time T can be set3-T2Reporting back to the initiator.
Figure 38 shows an example BLE radio 3900 with a superheterodyne receiver 3902 and transmitter 3904. The BLE radio 3900 may function as, for example, one of the transceivers 222 of figure 3 and may include or be part of one of the RF antenna module 40 and the RF circuitry 223. In another embodiment, the BLE radio 3900 functions as a transceiver in a portable access device, such as the transceiver 410 of the portable access device 400 of figure 6. The superheterodyne receiver 3902 converts the received signal to a fixed Intermediate Frequency (IF) using mixing. The superheterodyne receiver 3902 includes an RF (e.g., bandpass) filter 3906, a switching and balun 3908, a low noise amplifier 3910, a down-converter 3912, a bandpass filter and amplifier 3914, an analog-to-digital converter 3916, a demodulator 3918, and a correlation and protocol module 3920. The transmitter 3904 includes a processing module 3922, a protocol module 3924, a Gaussian Frequency Shift Keying (GFSK) modulator 3926, a digital to analog converter and low pass filter 3928, an up converter 3930, and a power amplifier 3932. The crystal oscillator(s) 3934 may generate one or more clock signals that may be distributed to the devices 3914, 3916, 3918, 3920, 3922, 3924, 3936, 3938 and the phase locked loops 3940, 3942. As an example, the processing module 3922 and the correlation and protocol module 3920 may be implemented as a single module and as part of one or more of the modules 204, 210, 211, 212 of fig. 3. The operations performed by modules 3922 and 3920 may be implemented by any of modules 204, 210, 211, 212 of fig. 3-4. One or more of the devices 3906, 3908, 3910, 3912, 3914, 3916, 3918, 3920, 3924, 3926, 3928, 3930, 3932, 3934, 3936, 3938, 3940, and 3942 may be implemented as part of the RF circuitry 223 and/or as part of one or more of the modules 204, 210, 211, 212.
Band-pass filter 3906 may be connected to a linearly polarized antenna and/or a circularly polarized antenna (denoted 3907). Downconverter 3912 downconverts the received signal from an RF frequency to an IF frequency based on the signal from phase locked loop 3942. The up-converter 3930 up-converts the IF signal into an RF signal based on a signal from the phase-locked loop 3940.
The GPSK modulator 3926 and demodulator 3918 may modulate and demodulate bits of a signal according to the GFSK protocol. FIG. 39 shows an example GFSK parameter definition map including a transmit carrier frequency F illustrating zero crossings and errorscThe figure (a). As an example, the transmission carrier frequency FcMay be 250KHz or 500KHz, symbol time of 1ps or 0.5ps, zero crossing error of 1/8(1Mbps) of 1ps or 1/8(2Mbps) of 0.5 ps.
Figure 40 shows a functional block diagram of a system 4100 for transmitting BLE packets. An example format of BLE packet 4101 is shown, which includes a preamble, an access address, a Protocol Data Unit (PDU), and a Cyclic Redundancy Check (CRC) bit field. This is an example of a packet that may be received by the correlation and protocol module 3940 of fig. 37 and/or generated by the processing module 3922 and/or the protocol module 3924.
The preamble of the packet is AA or 55 such that the last bit of the preamble is different from the first bit of the access address. The access addresses of the peripheral and central devices 4102, 4104 are the same. Sensors 4106 may be used to monitor the packets. The access address is the same for each packet and each connection interval. The access address follows BLE access address rules. Packets within the same connection interval are within the same RF channel. Example preambles and access addresses for BLE 1M packets and BLE2M packets are shown in figure 41. The preamble is a preamble of a and a preamble of 5 (AA or 55 at 1mbit/s and AAAA or 5555 at 2 mbit/s) such that the last bit of the preamble is different from the first bit of the access address. This is illustrated by the bits in circle 4200.
The access address for the advertisement channel packet may be 10001110100010011011111011010110b (0x8E89BED 6). Each link-layer connection between any two devices and each periodic advertisement has a different access address. The access address may be a 32-bit value. Each time a new access address is needed, the link layer may generate a new random value that satisfies the following rules. The access address is not an address corresponding to an existing link-layer connection on the network device. And (3) accessing an address: not an address for an enabled periodic advertisement; there are no six consecutive 0 s or 1 s; not the advertising channel packet access address; not a sequence differing by only one bit from the advertising channel packet access address; and does not include four equal octets. The number of translations of the access address does not exceed 24. The seed of the random number generator is from a physical source of entropy and has at least 20 bits of entropy. If the random number of the access address does not satisfy the above rules, new random numbers will be generated until the rules are satisfied. For implementations that also support BLE encoded physical layer (PHY), the access address may also have at least three 1's in the least significant 8 bits and may have no more than 11 translation numbers in the least significant 16 bits. In normal BLE packets, the preamble may discard the first bit of the access address, and then the access rule may sometimes discard the next bit of the access address (e.g., no more than 6 consecutive preambles of 0 or 1). This may cause ranging security issues because an attacker may predict bits, which may be mitigated or eliminated by implementations disclosed herein.
Figure 42 shows an example diagram of BLE packet signals illustrating that the corresponding bit first BLE signal 4300 represents a bit stream from the protocol module 3924 of figure 38. When the bits retain the same value, the normal BLE packet does not return to the carrier (or midpoint level). This is called non-return-to-zero recording. The corresponding bit of the first graph is shown above the graph. The second BLE signal 4302 represents a bit stream from the GFSK modulator (or gaussian filter) 3926. The gaussian filter adds 1/2 bits of time lag and is lost a little time during the transition. The corresponding bits of the second BLE curve are shown below the second BLE curve. As an example, the carrier frequency may be 2.402GHz, and the frequency of the BLE packet signal may vary between 2.402250GHz and 2.401750 GHz.
Figure 43 shows an example graph of BLE packet signals illustrating corresponding bits of a stronger BLE packet signal (e.g., a BLE packet signal with a greater RSSI) after leading edge sensing (leading edge sensing) and transmission with faster edge conditions. The first BLE signal 4400 represents a bit stream from the protocol module 3924 of figure 38. The second BLE signal 4402 represents a bit stream from the GFSK modulator (or gaussian filter) 3926. The third BLE signal 4404 represents a stronger BLE packet signal after transmission with a faster edge following the sensing of the leading edge of the gaussian bit. The third BLE signal 4404 may be generated by an attacking device. As can be seen, the edges are sloped and transition faster than the transition of the second BLE curve 4402. This results in the corresponding bit being earlier than the bit of the second graph (or the output of the GFSK modulator 3924). The ellipse 4406 indicates areas where differences can be detected and indicated.
Corresponding bits of the first BLE curve 4400 are shown above the first BLE curve 4400.
Corresponding bits of the second BLE curve 4402 are shown below the second BLE curve 4402. Corresponding bits of the third BLE curve 4404 are shown below the bits of the second BLE curve 4402 and are shifted to the left relative to the bits of the second BLE curve 4402.
Figure 44 illustrates the second and third BLE curves 4402, 4404 of figure 43, wherein the third BLE curve 4404 has been shifted relative to the second BLE curve 4402. The following operation may be performed to defend against a bit acceleration attack (bit acceleration attack). A bit-accelerated attack may refer to an attacking device accelerating the transmission of BLE signals to account for delays associated with the attacking device receiving, processing, and/or modifying and forwarding BLE signals (such as BLE signals transmitted from a key fob and/or other portable access device). Fig. 45 illustrates an example method of detecting an extended range type relay attack. Although the following operations of fig. 45 are described primarily with respect to the implementations of fig. 2-6, 11, and 14, these operations may be readily modified to apply to other implementations of the present disclosure. These operations may be performed iteratively. For example, the following operations may be performed by one or more of the modules 210, 211, 212.
The method may begin at 4600. In 4602, a sliding correlation function is used to align the received input waveform with an idealized gaussian waveform (or other suitable predetermined waveform) for a known bit pattern and bit rate, including scaling the peaks and aligning the received input waveform with the zero offset of the predetermined waveform. This may be accomplished by the correlation and protocol module 3920 of fig. 38. This may be done to identify, for example, a synchronous access word. An example of this is shown in fig. 44.
At 4604, the portion (or portions) 4605 of the received waveform that occurs just after the zero crossing in time and before the next peak value of the predetermined waveform is integrated and accumulated (or summed). This is called positive accumulation.
At 4606, the portion(s) 4607 of the received waveform that is a time period after the peak in time and occurs before the next zero crossing is integrated and accumulated. This is also referred to as positive accumulation.
At 4608, the resulting accumulated values to be determined in 4604 and 4606 are averaged over the number of transitions used to provide an indication of the bit-accelerated attack level. The accumulated values may be averaged separately to provide two averages, or the accumulated values may be added and then averaged to provide a single average.
At 4610, based on the one or more averages and one or more predetermined thresholds, it is determined whether an attack has occurred and/or is likely to have occurred. At 4612, if an attack has occurred and/or may have occurred, then operation 4614 is performed, otherwise operation 4616 is performed. At 4614, a countermeasure, such as one of the previously mentioned countermeasures, is performed including preventing access and/or operation to the corresponding vehicle. One or more alerts may also be generated. As another example countermeasure, data related to the attack may be stored in memory and/or transmitted to a network device of the vehicle owner and/or a central monitoring station. At 4616, access to and/or operational control of the vehicle is allowed if the attack has not occurred and/or is likely not to occur. The operation control may include: such as unlocking or locking of doors of the vehicle, remote starting of an engine of the vehicle, interior climate control adjustments of the vehicle, etc. At 4618, the one or more averages may be discarded and/or previously aggregated and accumulated data may be discarded. If a sliding window is used to monitor the received signal, the previous portion of the data may be discarded, while the more recent portion may be retained for subsequent integration, accumulation, and averaging with the newly received data.
Fig. 46 shows a vehicle 5200 including a Round Trip Time (RTT) responder 5202 and an RTT initiator 5204, and a portable access device 5206 including an RTT initiator 5208 and an RTT responder 5210. As used herein, an "initiator" may refer to a network device that includes a BLE radio, a transmitter, and/or a receiver and initiates a signal or tone exchange. As used herein, a "responder" may refer to a network device that includes a BLE radio, a transmitter, and/or a receiver and that responds to a signal and/or tone received from an initiator. RTT responders 5202, 5210 and RTT initiators 5204, 5208 may be implemented, for example, by RF antenna module 40, RF circuitry 223 and/or modules 210, 211, 212 of fig. 3 and include corresponding transmit and receive circuitry. The vehicle 5200 may include an antenna module having a single polarized antenna and a circularly polarized antenna as described above. RTT responder 5202 and RTT initiator 5204 may use antennas for transmission and reception. The antennas provide polarization diversity with the antennas (e.g., single-polarized antennas) used by RTT initiator 5208 and RTT responder 5210, such that at any time at least one of the above-described antennas of vehicle 5200 has at least one polarization axis that is not cross-polarized and that is not co-polarized with the polarization axis of at least one of the antennas of portable access device 5206.
The devices 5202, 5204, 5208, 5210 may each include a control module as described above to perform any of the described operations. The devices 5202, 5204, 5208, 5210 may transmit and receive RF signals on random channels (e.g., 40 BLE channels over an 80MHz spectrum). The devices 5202, 5208 may communicate with each other, including sending and receiving signals, while the devices 5204, 5210 may communicate with each other, including sending and receiving signals. Communication between the devices 5202, 5208 may be simultaneous to communication between the devices 5204, 5210. For security reasons and to detect attacks, the transmission of signals for determining the RTT may be transmitted simultaneously and in a bidirectional manner. The devices 5202, 5204 may share frequencies for communication with the portable access device 5206. The frequencies may be indicated in a predetermined order, followed by the devices 5202, 5204, 5208, 5210. If a bandpass filter is used to monitor both channels simultaneously, the filter will introduce a propagation delay.
A typical bandpass filter delay is 0.5 per bandwidth (or 0.5 per bandwidth). The channel spacing of the protocol, the randomness of the channel selection, the randomness of the transmit direction over time, and the simultaneous transmission all force the bandpass filter to detect bits with group delay (group delay) that are large compared to the measurable round trip time delay. This further increases the difficulty of the attack device performing the extended range type relay attack. The vehicle 5200 and the portable access device 5206 may set the transmit power level and transmit channel spacing, respectively, so that it is impractical for an attacking device, for example, to receive a signal with a filter wide enough to relay with a short enough delay, but narrow enough to analyze the signal.
In an embodiment, a signal is sent to measure the direct time of flight and determine if there is a predetermined amount of delay (e.g., 10-500 nanoseconds (ns)) typically associated with a range-extended attack device. When relaying a signal between the vehicle 5200 and the portable access device 5206, the extended range type attack device may delay the transmitted signal by a predetermined amount. The above-described bi-directional and simultaneous transmission and reception makes it difficult for an attacking device to determine at any moment the frequency, channel and direction of the transmitted signal. It is also difficult for an attacking device to avoid relaying a signal without a predetermined amount of delay.
Fig. 47 shows a vehicle 5200 including an RTT responder 5202 and an RTT initiator 5204, and a portable access device 5206 including an RTT initiator 5208 and an RTT responder 5210. Fig. 47 shows signal paths through the corresponding antennas 5300, 5302, 5304, 5306. In an embodiment, antennas 5300, 5302 have a total of three polarizations, and antennas 5304, 5306 have a total of two polarizations. In another embodiment, antennas 5300, 5302 have a total of two polarizations, and antennas 5304, 5306 have a total of three polarizations.
Fig. 48 shows a vehicle 5200 including an RTT responder 5202 and an RTT initiator 5204, a portable access device 5206 including an RTT initiator 5208 and an RTT responder 5210, and an extended range type relay attack device 5400. The range extension attack device 5400 includes a control module 5402, and the control module 5402 includes a band pass filter 5404, a bit signal direction detector 5406, and a bit acceleration attack module 5408. A band pass filter 5404 is used to detect incoming bits, but with an associated lag time. The bit signal direction detector 5406 determines the direction in which the bit is traveling (e.g., from vehicle to portable access device or from portable access device to vehicle). The bit acceleration attack module 5408 cannot accelerate bits without introducing lag time in parts of the symbol (or bit), which can be detected using a sliding correlation function aligned with an ideal waveform and averaging the symbol (or bit) shape over multiple symbols. The lag time may be detected by an access module of the vehicle when determining whether an attack is occurring.
As shown, the range extension attack device 5400 includes an amplifier 5410 for receiving and transmitting purposes, such as a Low Noise Amplifier (LNA) and a power amplifier. The range extension attack device 5400 may also include mixers for down-conversion and up-conversion purposes. The amplifier 5410 is connected to an antenna 5412.
In addition to performing the above-described communication simultaneously, a channel may be pseudo-randomly selected, and an access address may also be pseudo-randomly selected. The random selection may be made on the vehicle and may be shared with the portable access device in advance. Instead, the selection may be made at the portable access device. Rather, the selection may be made by a secure encryption technique, where the keying material is from one or both of the devices contributing to the pseudo-randomly selected channel sequence and/or access address sequence. In this case, the pseudo-random sequence of access addresses is used as a cryptographic security bit sequence for the round trip timing measurement exchange. In the case where the simultaneous transmission and reception operation is performed on a random channel having a randomly selected access address, where the response is on the same channel as the initiator and the response access address is different from the initiator access address, it is difficult for the range extension attack device to perform the attack without being detected by the access module of the vehicle and/or the control module of the one or more portable access devices. The range extension attack device must: listening to all channels in both directions simultaneously; determining the direction of the message passing through the range expansion attack equipment; and detecting the bits as early as possible and sending the bits an appropriate amount of time ahead in both directions to convince the vehicle's initiator and the one or more portable access devices. The range extension attack device must persuade the initiator and the one or more portable access devices of the vehicle to be closer than the actual portable access device and at the correct distance from the vehicle to allow access and/or operational control of the vehicle. In addition, using gaussian filtering for BLE bits, the attacking device has a small window that is less than about 10-100ns ahead of the bit detection time used to detect and transmit the bits ahead.
In an embodiment, RF signals associated with the above-described simultaneous communications are monitored by the modules 210, 211, 212 of fig. 3, and the stated initiators and responders monitor and/or determine RSSI values and antenna polarization states (e.g., degrees of polarization between transmit and receive antennas) of the signals. Based on the RSSI values and the polarizations, one or more of the modules 210, 211, 212 determine the path, frequency, channel, and antenna pairs that are optimal for communication. The signal associated with the shortest path (or least interference), best RSSI value, maximum polarization, etc. is used to indicate which path, frequency, channel, and antenna pair to use. This information can also be used to determine which device transmits and which device receives at any time. The selection of transceiver chips and channels on each device may be random. In an embodiment, one device (at the vehicle or portable access device) may transmit while the other device does not transmit but receives. This role can then be switched so that the first device is receiving and the second device is transmitting and not receiving.
While many of the techniques described above and below include monitoring, generating, receiving, transmitting, and/or measuring various parameters at a vehicle access module, and detecting a range-extended relay attack based on this information, the techniques may be modified such that some or all of these operations are performed at a control module (or other module) of a portable access device, such as any of the portable access devices disclosed herein. Similarly, various operations are described as being performed at a portable access device; these operations may be performed at an access module of the vehicle.
Examples of different BLE RF transmission frequencies are 2.410 gigahertz (GHz), 2.412GHz, 2.408GHz, and 2.414 GHz. These frequencies and other frequencies may be used by RTT initiators and responders and/or corresponding senders and recipients.
In an embodiment, other transmitters of the vehicle and/or portable access device are used to lightly load one or more channels to cause the attacking device to have a narrow low pass filter to detect the RF signals transmitted by the initiator and responder. The one or more channels may include channels used by the initiator and responder or may be nearby channels. The signals transmitted on the one or more channels may be dummy signals.
Figure 49 shows two of BLE radios 3900 (denoted as 3900A and 3900B). The first BLE radio 3900A functions as an initiating and measuring device. The second BLE radio 3900B functions as a reflective (or responsive) device. Initiating and measuring device 3900A may measure an RTT that transmits packets from first BLE radio 3900A to second BLE radio 3900B, a time of second BLE radio response, and a time of transmitting packets from second BLE radio 3900B to first BLE radio 3900A. In another embodiment, the RTT includes the time at which packets are sent from the processing module 3922A of the first BLE radio 3900A to the correlation and protocol module 3920B of the second BLE radio and from the processing module 3922B or protocol module 3924B back to the demodulator 3918a or correlation and protocol module 3920A. This may include measuring travel time: slave process module 3922A; via protocol module 3924A, GFSK modulator 3926A, D/a and low pass filter 3928A, upconverter 3920A, power amplifier 3932A, switch and balun 3908A, and band pass filter 3906A; to BLE radio 3900B; through bandpass filter 3906B, switch and balun 3908B, low noise amplifier 3910B, down-converter 3912B, bandpass filter and amplifier 3914B, A/D3916B, and demodulator 3918B to correlation and protocol module 3920B. The time to travel from the demodulator 3918B or correlation and protocol module 3920B to the protocol module 3924B or processing module 3922B may also be determined. The time from the protocol module 3924B or the processing module 3922B through the GFSK modulator 39 3926B, D/a and low pass filter 3928B, up-converter 3930B, power amplifier 3932B, switch and balun 3908B, band pass filters 3906B and 3906A, switch and balun 3908A, low noise amplifier 3910A, down-converter 3912A, band pass filter and amplifier 3914A, A/D3916A, and demodulator 3918A or correlation and protocol module 3920A may also be determined. Although BLE radio 3900A is described as an initiator and BLE radio 3900B is described as a responder, the operational roles may be switched such that BLE radio 3900B is the initiator and BLE radio 3900A is the responder.
The following operations may be performed to accurately determine RTT between two BLE radios of the vehicle (e.g., BLE radios 3900A, 3900B of figure 49) and/or between a BLE radio of the vehicle and a BLE radio of the portable access device. These operations are performed to prevent attacks and/or to easily detect when an attack is being performed and/or when an attack has occurred. The following operations may be performed individually or in any combination. In an embodiment, a large predetermined number of packets are exchanged back and forth between BLE radios. The initiator may measure and/or estimate the RTT of signals transmitted between BLE radios. This may include: time T1 when the packet was sent from the first BLE radio to the second BLE radio, time T2 when the second BLE radio responded, time T3 when the second BLE radio sent the packet back to the first BLE radio, time T4 when the first BLE radio received the packet from the second BLE radio.
In an embodiment, the a/D and D/a clocks of the BLE radio and/or phase locked loop are jittered between packets. In addition to dithering the clock where possible, a cryptographic random variation may be added, as is known for BLE radios, for when to transmit the Least Significant Bit (LSB) generated by the digital timer. The random change of the password is used, so that the attacking device cannot predict the precise moment when the transmission occurs.
In an embodiment, each packet includes a pre-agreed upon cryptographic random multi-bit identifier (PACRMBI) that is, for example, 16 to 256 bits large. In another embodiment, the packet bit content from the initiator and responder is indistinguishable to the attacking device. The attacking device cannot identify which direction the packet came from, or whether the packet is an initiator packet or a responder packet, based on the bit content of the packet.
In an embodiment, the channel of the BLE radio is cryptographically randomized. In an embodiment, the determination of which of the BLE radios is the initiator or responder is cryptographically randomized. In an embodiment, one or both of the BLE radios transmits a dummy packet that the attacking device cannot distinguish from other packets transmitted by the BLE radios. The selection of whether the BLE radio transmits dummy packets is cryptographically randomized and may be randomly switched. This makes it difficult for an attacking device to determine which are valid packets and the direction in which the packets are transmitted between BLE radios.
In an embodiment, the polarizations of the set of antennas used by the BLE radio are initially cryptographically randomized. A heuristic to select which antenna permutations between BLE radios provide the best "antenna-channel" in the channel set is used. This may include: using a heuristic of selecting a higher received signal strength; compensating for antenna gain at frequency, monitoring a plurality of channels; using the antenna combination with the highest average or median power; and/or using a rayleigh fading estimator or a kalman filtering estimator. This may reduce the cryptographically random antenna patterns and focus on "antenna-channels" with maximum power and minimum cross-polarization.
In an embodiment, in-phase and quadrature-phase (IQ) streams at the receiver are up-sampled (or interpolated) before sending the IQ stream with an idealized up-sampled IQ stream matched to PACRMBI to the correlation and protocol module of one BLE radio of the corresponding BLE radio. As an alternative to using PACKRMBI's, the transmitted message may be encrypted and bit decoded upon receipt and then converted to an idealized up-sampled IQ stream. The two upsampled streams may be sent through a correlation and protocol module 3920, which may monitor the upsampling clock edges where there is sufficient correlation to match PACRMBI. The correlation and protocol module 3920 selects the largest of the matched clock edges. Other clock recovery methods may be used to interpolate the sub-bit timings in the round trip timing of the bit stream in the communication channel. This may be performed in conjunction with the upsampling correlation or in conjunction with normal clock sampling.
In an embodiment, amplifier settings are communicated between BLE radios. The amplifier settings are sufficient to compensate for any frequency and amplifier gain variations in propagation delay between BLE radios.
In another embodiment, the measured die temperature in the BLE radios is communicated (or shared) between the BLE radios to compensate for any temperature-based frequency and amplifier gain variations in propagation delay between the BLE radios.
Another operation that may be performed is to communicate balun changes between BLE radios. Another operation is to add a short (e.g., 6 μ s) but cryptographically random length (e.g., 4 to 8 μ s) continuous wave tone to the packet pair for simultaneous tone-switched ranging while making round-trip timing measurements.
Fig. 50 shows a position and distance determination system 5600, which includes an RTT initiator 5602, an RTT responder 5604, and an RTT sniffer 5606. RTT initiator 5602 and RTT responder 5604 may be used as any of the initiators, responders, BLE radios, RF circuits disclosed herein. The RTT sniffer 5606 may be located at a vehicle with one of the RTT devices 5602, 5604 and include one of the antenna modules 40 of fig. 2, while the RTT device in the vehicle includes the other of the antenna modules 40. Devices 5602, 5604, 5606 can each include a control module, as described above, to perform any of the described operations. Polarization diversity as described above is provided: between the antennas of the RTT devices 5602, 5604; and between the antenna of one of the RTT devices 5602, 5604 located inside the vehicle and the RTT sniffer 5606. Polarization diversity is particularly used when performing round-trip timing measurements. Each of the RTT devices 5602, 5604 may include a single polarized antenna and a circularly polarized antenna.
One of the RTT devices 5602, 5604 located in the vehicle may be referred to as a master device, and the other one of the RTT devices 5602, 5604 is referred to as a slave device. When the master device sends a challenge signal to the slave device, RTT sniffer 5606 acts as a listener and detects (i) when a challenge signal is sent to RTT sniffer 5606 and/or when a challenge signal is received at RTT sniffer 5606, and (ii) when the slave device sends a response signal to the challenge signal, and/or (iii) when RTT sniffer 5606 receives the response signal. The RTT sniffer 5606 may then determine the location of the slave device using triangulation based on the time of transmission and/or reception of the challenge signal and the time of transmission and/or reception of the response signal. The master device may also measure the round trip timing associated with the challenge and response signals in order to measure the direct path between the antennas rather than the bounce path. This prevents the nulls of the antennas from being aligned and cross-polarized.
The master device and RTT sniffer 5606 cooperate to estimate the range to the slave device. The master device may implement equations 5-7 below to determine the amount of time T for sending a challenge signal from the master device to the slave deviceMSWherein: t is SMIs the amount of time that the response signal is sent from the slave device to the master device; t isRXIs the time at which the response signal is received at the master device; t isTXIs the time at which the challenge signal is sent from the master device; t isSDELAYIs the amount of delay time for the slave device to respond with a response signal after receiving the challenge signal; and FixedOffset1Is a first amount of offset time and may be greater than or equal to 0.
TMS+TSM=TRX-TTX-TSDELAY+FixedOffset1 (5)
TMS=TSM (6)
The RTT sniffer 5606 knows: when a challenge signal is received at RTT sniffer 5606; when a response signal is received at RTT sniffer 5606; and a number of slave clock cycles between receiving the challenge signal by the slave device and transmitting the response signal by the slave device. RTT sniffer 5606 (or listener) can use equations8 determining the time T at which the RTT sniffer 5606 received the response signalSLRXAnd the time T at which the RTT sniffer 5606 receives the challenge signalMLRXThe difference between, wherein: t isSLIs the amount of time that the RTT sniffer 5606 receives the response signal; FixedOffset2Is a second amount of offset time, and may be greater than or equal to 0; t isMLIs the amount of time that the RTT sniffer 5606 receives the challenge signal; t isSLRXIs the time that the RTT sniffer 5606 receives the response signal; and TMLRXIs the time that the RTT sniffer 5606 receives the challenge signal.
TMS+TSDELAY+TSL+FixedOffset2-TML=TSLRX-TMLRX (8)
Since the master device and RTT sniffer 5606 are cooperative, information is shared so that one or more of these devices can estimate the distance to the slave device based on equations 9-11. Can use T MSAnd TSLThe sum is substituted to provide equations 9-11.
By measuring the time of arrival of the challenge signal and the response signal at the RTT sniffer 5606 and sharing this information between the RTT sniffer 5606 and the master device, the distance between the vehicle and the slave device can be estimated. The arrival time and the known time T may be used by, for example, the master deviceMSAnd a corresponding known signaling rate to estimate the distance. The RTT of the challenge signal may be determined based on the measured arrival time. The range may then be determined based on the RTT and a known signaling rate.
Fig. 51 shows another position and distance determination system 5700, which 5700 includes an RTT initiator 5702, an RTT responder 5704, and a plurality of RTT sniffers 5706. RTT initiator 5702 and RTT responder 5704 may be used as any of the initiators, responders, BLE radios, RF circuits disclosed herein. The RTT sniffer 5706 may be located at the vehicle with one of the RTT devices 5702, 5704 and include an antenna module (similar to the antenna module 40 of fig. 2). The devices 5702, 5704, 5706 may each include a control module as described above to perform any of the described operations. The RTT device in the vehicle may also include an antenna module similar to the antenna module 40 of fig. 2. Polarization diversity is provided: between the antennas of the RTT devices 5702, 5704; and between the antenna of one of the RTT devices 5702, 5704 located within the vehicle and the RTT sniffer 5706. Polarization diversity is particularly used when performing round-trip timing measurements to measure the direct path between antennas rather than the bounce path. This prevents the nulls of the antennas from being aligned and cross-polarized.
One of the RTT devices 5702, 5704 located in the vehicle may be referred to as a master device, while the other one of the RTT devices 5702, 5704 is referred to as a slave device. RTT sniffer 5706 acts as a listener when the master sends a challenge signal to the slave and detects when a challenge signal is sent and when a response signal is sent by the slave to the challenge signal. The RTT devices 5702, 5704 may operate similarly to the RTT devices 5602, 5604 of fig. 50. Each RTT sniffer 5706 may operate similarly to RTT sniffer 5606.
The time TAB is the amount of time that the challenge signal is sent from the RTT initiator 5702 to the RTT responder 5704. The time TBA is the amount of time that a corresponding response signal is sent from the RTT responder to the RTT initiator. The time TAC is the amount of time the first RTT sniffer receives the challenge signal. The time TBC is the amount of time the first RTT sniffer receives the response signal. The time TAD is the amount of time the second RTT sniffer receives the challenge signal. The time TBD is the amount of time the second RTT sniffer receives the response signal. Time TAE is the amount of time that the third RTT sniffer receives the challenge signal. The time TBE is the amount of time the third RTT sniffer receives the response signal. When TAB and TAC are known, TBC may be calculated. When TAB and TAD are known, TBD can be calculated. When TAB and TAE are known, TBE can be calculated.
If there are enough RTT sniffers, the time TAB can be calculated. For example, if three RTT initiators know the location of the RTT initiator with respect to the master (or initiator), the time TAB may be calculated. This can be done using equations 12-17 and assuming that all reflections are instantaneous, where: trxc is the time when the first RTT sniffer receives the challenge signal; TRxBC is the time when the first RTT sniffer receives the response signal; TRxAD is the time when the second RTT sniffer receives the challenge signal; TRxBD is the time that the second RTT sniffer receives the response signal; TRxAE is the time when the third RTT sniffer receives the challenge signal; TRxBE is the time when the third RTT sniffer receives the response signal; deltaRxAtC is the time difference between the first RTT sniffer receiving the response signal and the first RTT sniffer receiving the challenge signal; deltaRxAtD is the time difference between the second RTT sniffer receiving the response signal and the second RTT sniffer receiving the challenge signal; deltaRxAtE is the time difference between the third RTT sniffer receiving the response signal and the third RTT sniffer receiving the challenge signal. The location of the slave device (or responder) may also be determined using equations 18-25, where: xa is the x coordinate of the master device; ya is the y coordinate of the master; za is the z coordinate of the master; xb is the x coordinate of the slave device; yb is the y coordinate of the slave device; zb is the z-coordinate of the slave device; xc is the x-coordinate of the first RTT sniffer; yc is the y-coordinate of the first RTT sniffer; zc is the z coordinate of the first RTT sniffer; xd is the x-coordinate of the second RTT sniffer; yd is the y-coordinate of the second RTT sniffer; zd is the z coordinate of the second RTT sniffer; xe is the x-coordinate of the third RTT sniffer; ye is the y coordinate of the third RTT sniffer; ze is the z coordinate of the third RTT sniffer. The x, y, z coordinates of the master and slave are known and the x, y, z coordinates of the slave are determined. As described above, TBC, TBD, and TBE may be determined in a similar manner.
TAB+TBC-TAG=TRxBC-TRxAC=deltaRxAtC (12)
TAB+TBD-TAD=TRxBD-TRxAD=deltaRxAtD (13)
TAB+TBE-TAE=TRxBE-TRxAE=deltaRxAtE (14)
TBC=deltaRxAtC+TAG-TAB (15)
TBD=deltaRxAtD+TAD-TAB (16)
TBE=deltaRxAtE+TAE-TAB (17)
Equations 18-21 are trilateration equations.
(xb-xa)2+(yb-ya)2+(zb-za)2=TAB2 (18)
(xb-xc)2+(yb-yc)2+(zb-zc)2=TBC2 (19)
(xb-xd)2+(yb-yd)2+(zb-zd)2=TBD2 (20)
(xb-xe)2+(yb-ye)2+(zb-ze)2=TBE2 (21)
Equations 22-25 can be obtained by replacing 4 equations with 4 variables.
(xb-xa)2+(yb-ya)2+(zb-za)2=TAB2 (22)
(xb-xc)2+(yb-yc)2+(zb-zc)2=(deltaRxAtC+TAC-TAB)2 (23)
(xb-xd)2+(yb-yd)2+(zb-zd)2=(deltaRxAtD+TAD-TAB)2(24)
(xb-xe)2+(yb-ye)2+(zb-ze)2=(deltaRxAtD+TAD-TAB)2(25)
When three RTT sniffers are used (e.g., the RTT sniffer 5706 shown), trilateration may be performed using three circles to measure distance and determine the location of the slave device relative to one of the RTT devices 5702, 5704 and/or the corresponding vehicle. This may be performed at the master device and/or at one or more RTT sniffers. The information determined at the master device and the RTT sniffer may be shared with each other. The time, distance and/or location may be determined and updated periodically accordingly.
In a vehicle, the round trip timing measurements may be periodically updated if an object (e.g., the head of a vehicle occupant) is present near and/or between the antenna module of the host device and one or more RTT sniffers such that the object may interfere with the signal sent by the host device. This operation may be performed to measure the distance between the host device and the RTT sniffer to detect when the corresponding physical environment/system has changed.
Fig. 52 shows a first network device (or vehicle) 5800 and a second network device (or portable network device) 5802. The first network device 5800 includes a tone switch responder 5804 and a tone switch initiator 5806. The tone swap is also referred to as an unmodulated carrier tone swap. The second network device 5802 includes a tone switch initiator 5808 and a tone switch responder 5810. The devices 5804, 5806, 5808, 5810 may be implemented as any of the other BLE radios, RF circuits, initiators, responders, etc., disclosed herein. At least one of the devices 5804, 5808 and at least one of the devices 5806, 5808 may include or be connected to a single polarized antenna and a circularly polarized antenna. Devices 5804, 5806, 5808, 5810 may each include the antenna module 40 of fig. 2 and/or the antenna shown in fig. 11.
A tone exchange may be performed between the responder 5804 and the initiator 5808, and between the initiator 5806 and the responder 5810. The RTT measurement may be sent in the same packet as the switch tone. Devices 5804, 5806, 5808, 5810 may randomly select a channel for transmission of a packet. The transmission of the packet may occur simultaneously with the reception of the packet. For example, the initiator 5808 may transmit tones to the responder 5804 on a first channel, while the initiator 5808 receives tones from the responder 5804 on a second channel. While initiator 5804 is transmitting and/or receiving tones, initiator 5806 may transmit and/or receive tones.
The network devices 5800, 5802 may be synchronized in advance, for example, by a serial handshake, to synchronize clocks of the network devices 5800, 5802. This synchronization may be performed to allow the network devices to simultaneously transmit signals to each other. For example, two 1MHz signals transmitting data may each be transmitted at 1 Mbps. The signals may be 2MHz apart from each other. This prevents the attacking device from being able to perform attacks such as range extension attacks or attacks that include active manipulation of tones. If an attacker uses a 1MHz wide band pass filter, the band pass filter will have a large amount of lag time and therefore not respond fast enough to make an attack impossible. If an attacker uses a broadband bandpass filter (such as a 4Mhz bandpass filter), the corresponding signal eye pattern will have too much noise to discern the signal transmitted by the network devices 5800, 5802. As another example, signals may be transmitted from a network device at a symbol transmission rate that is less than or equal to a predetermined amount of time (e.g., 1ps per symbol). This provides for fast transmission, thereby preventing attacks. In addition, the simultaneous transmission of the dual signals further prevents the attacker from being successful, as the attacker would need to detect and affect both signals. As described above, both signals may be transmitted by the same network device or different network devices at different frequencies.
As another example, a Received Signal Strength Indicator (RSSI) parameter may be monitored to determine if a network device is near a vehicle and then a series of tone swapping performed to measure distance. Based on the user's door handle touch, a tone swap may be performed to ensure that there is no attack. Multiple round trip timing measurements may be performed to determine the distance of the network device relative to the vehicle.
The distance determination techniques described above may be used in conjunction with other techniques for determining RTT values disclosed herein. The direction of travel of the tones between the devices 5804, 5806, 5808, 5810 may be random.
In one embodiment, the control module of the first network device 5800 plots a change in phase versus a change in frequency for each of a plurality of tones that are exchanged to generate a plurality of linear curves. The control module determines a slope of the curve that provides a ratio of the phase change to the frequency change. The slope is then used to determine a distance between adjacent curves, which is related to the distance between the first network device 5800 and the second network device 5802.
Fig. 53 shows a position determination system 5900, the position determination system 5900 including a tone swap initiator 5902, a tone swap responder 5904, and a tone swap sniffer 5906. The tone swapping initiator 5902 and tone swapping responder 5904 may function as any of the initiators, responders, BLE radios, RF circuits disclosed herein. The tone exchange sniffer 5906 may be performed similarly to the RTT sniffer 5606 of fig. 50 and may be located at the vehicle with one of the tone exchange devices 5902, 5904 and include one of the antenna modules 40 of fig. 2, while the tone exchange device in the vehicle includes the other of the antenna modules 40. The devices 5902, 5904, 5906 may each include a control module as described above to perform any of the operations described above. Polarization diversity is provided: between the antennas of the tone switching devices 5902, 5904; and between the antenna of one of the tone switching devices 5902, 5904 located in the vehicle and the tone switching sniffer 5906. Polarization diversity is used in particular when round-trip timing measurements are performed.
One of the tone switching devices 5902, 5904 located in the vehicle may be referred to as a master device, while the other one of the tone switching devices 5902, 5904 is referred to as a slave device. When the master device transmits a tone to the slave device and when the slave device transmits a tone to the master device, the tone switching device 5906 acts as a listener and detects (i) when a tone is transmitted to the tone switching device 5906 and/or when a tone is received at the tone switching device 5906, (ii) when the slave device transmits a tone to the master device, and/or (iii) when the tone switching device 5906 receives a tone transmitted by the slave device. The slave device may act as a reflector and transmit the tones received from the master device back to the master device. The master device and/or the sniffer device may prevent at least one of access to the vehicle or operational control based on the time of arrival of the tone, the round trip timing measurements, and/or the estimated distance between the devices.
Fig. 54 illustrates a method of determining distances between an initiator and a responder and between a responder and a sniffer. Although the following operations of fig. 54 are described primarily with respect to the implementations of fig. 50 and 53, these operations may be readily modified to apply to other implementations of the present disclosure, such as the implementations of fig. 2-6, 11, 14, 39, and 46-49. These operations may be performed iteratively. Although the method is described primarily with respect to the implementation of fig. 53, the method may be applied to other embodiments of the present disclosure.
The method may begin at 6000. At 6002, the tone swap initiator 5902 transmits a tone signal including the tone to the tone swap responder 5904. The pitch may be expressed as:where A is the tone switching initiator 5902, B is the tone switching responder 5904, τABIs the time to travel from a to B and is directly related to the distance between the tone swap initiator 5902 and the tone swap responder 5904, ω is the frequency,is the phase of the tone at the tone switching initiator 5902 and t is time.
At 6004, at tone switch responder 5904 with a delayReceive tones and delay at tone switching sniffer 5906A tone is received. At audio exchange responder 5904, the received tone signal is downconverted to baseband, which may be represented by equation 26.
At the audio exchange sniffer 5906, the received tone signal is downconverted to baseband, which can be represented by equation 27.
At 6006, the tone swap initiator 5902 receives the tone from the tone swap responder 5904, and the tone swap responder 5904 retransmits the tone signal as the second tone signal back to the tone swap initiator 5902. The tone may be represented asThe received second tone signal may be represented by equation 28. The tone switching sniffer 5906 also receives a second tone signal, which can be represented by equation 29.
At 6008, the tone swap initiator 5902 receives a phase signal from the tone swap responder 5904 indicating a natural logarithmic tone value having a tone phase difference when received at the tone swap responder 5904. Therefore, the tone swap responder 5904 sends the measured phase to the tone swap initiator 5902, and multiplies the values in the tone swap initiator 5902 as shown in equation 30.
At 6010, based on the received tone signal, the tone swap sniffer 5906 determines tone values associated with: a tone phase difference between when sent from the tone switching initiator and when received at the tone switching sniffer; and a tone phase difference between when sent from the tone switch responder and when received at the tone switch sniffer. The pitch value can be expressed asAnd
at 6012, the initiator 5902 and/or the sniffer 5906 determine distances between the initiator 5902 and the responder 5904 and between the initiator 5902 and the sniffer 5906. The distance value may be determined in a similar manner as described above when sniffing the round trip time, see, e.g., equations 12 and 15 and their corresponding description. Phase is used instead of round trip time. The calculation may include using equation 31, where the pitch value is measured or determined at the sniffer 5906 And is a priori and the pitch value is determined at responder 5904
The initiator 5902 and/or sniffer 5906 may take the inverse logarithm of the result of equation 31 to provide a time τBCAnd τAB. The distances between the responder 5904 and the sniffer 5906 and between the initiator 5902 and the responder 5904 may be determined based on these times and the known sending rates of the tone signals. The method may end at 6014. The initiator 5902 or the sniffer 5906 may prevent at least one of access to the vehicle or operational control based on the estimated at least one distance.
Figure 55 shows an example of a passive tone switching and phase difference detection system 6100. System 6100 includes a Phase Locked Loop (PLL)6102, a phase module 6104, a transmitter 6106, a receiver 6108, and an antenna module 6110. The antenna module 6110 may be similar to the antenna module 40 of fig. 2. The transmitter 6106 transmits a first tone, which may be the output of the PLL 6102 and reflected by a reflector 6112 back to the receiver 6108. The output of the PLL and the reflected tone signal are provided to the phase module 6104. The phase module 6104 determines the phase difference between the output of the PLL and the reflected tone signal. The phase module 6104 or other module disclosed herein determines the distance between the transmitter 6106 and the reflector 6112 based on the phase difference. The phase module 6104 or other modules disclosed herein may prevent access to the vehicle interior and/or operational control of the vehicle based on the determined distance.
Fig. 56 shows an example of an active tone swapping and phase difference detection system 6200. The system 6200 operates similarly to the system 6100 of fig. 55. The sender and receiver 6106, 6108 are represented by block 6202. The reflector 6112 of fig. 55 may be replaced with a responder device 6204 for active tone swapping. The responder device 6204 may receive a first tone signal having a first one or more tones from transmitter 6106 and respond with a second tone signal. The second tone signal may include the one or more tones and/or one or more other tones. The second tone signal is sent back to the receiver 6108.
Fig. 57 shows an initiator packet 6300 and a response packet 6302 for RSSI and time-of-flight measurements. Initiator packet 6300 may include a number of fields such as a preamble, a synchronization access word (e.g., a pseudo-random synchronization access word), a data field including data, a Cyclic Redundancy Check (CRC) field including CRC bits, and a Continuous Wave (CW) tone field including CW tones. The response packet 6302 may include a CW tone field, a preamble, a synchronization access word, a data field, and a CRC field.
The initiator device may transmit an initiator packet 6300, which may be received at the responder device. The responder device may then generate a response packet 6302 and send the response packet back to the initiator device. This can be done for tone switching, phase difference determination, round trip timing measurement. The distance between the devices can then be determined. These measurements and calculations may be performed to detect an extended range relay attack. In an embodiment, the initiator and responder pre-negotiate what the synchronous access word will be based on a predetermined list. The synchronous access word includes an access address. The initiator may, for example, measure the amount of time to receive (i) a response packet after sending the initiator packet and/or (ii) a synchronous access word. The amount of time and the synchronized access word may be compared to a predetermined amount of time and a predetermined synchronized access word. If the comparison performed yields a match, no range-extended relay attack has occurred. However, if the received sync access words do not match and/or the amount of time differs from the expected amount of time by more than a predetermined amount, an extended range relay attack may have occurred.
In an embodiment, the initiator and responder exchange a predetermined key, a list of synchronized access words, and a time at which each synchronized access word is to be transmitted. The sync access word may be randomly selected when initially created. This lets the responder know the correct key and/or sync access word to respond when the initiator packet is received. The key may be included in the response packet. In another embodiment, the initiator packet and the response packet do not include a preamble, as shown in fig. 58. In an embodiment, the length of the CW tone is 4-10 μ s.
In another embodiment, the initiator packet and the response packet have the same format as shown in fig. 59. Each packet includes: a first CW tone as a first field; and a synchronous access word; a data field; a CRC field; and a second CW tone as a last field. Another example of an initiator packet and a response packet having the same format is shown in fig. 60, where each packet includes: a first CW tone as a first field; and a sync word comprising PACRMBI; a PDU field including a PDU; a Media Access Controller (MAC) field; a CRC field; and a second CW tone as a last field. The CW tones of fig. 57-60 may be cipher random length tones and may be examined by the initiator when received. For example, an extended range relay attack may occur when the CW tone received from the responder is incorrect. With the embodiments of fig. 59-60, the sync word round trip timing prevents CW tone switching from going beyond the ambiguity range (e.g., 75 meters) in 2MHz channel tone steps. The initiator packet and responder packet mentioned above may be transmitted at the same frequency. By having the initiator and responder packets have the same format, the attacking device cannot distinguish which packet is the initiator packet and which packet is the responder packet. In one embodiment, the CW tone at the end of the packet is not included.
In an embodiment, the timing, frequency, length, power level, amplitude and content of the CW tones and the synchronous access words of the initiator and responder packets are examined at the initiator and responder to determine if correct and/or consistent and to identify if an attack has occurred. In an embodiment, the packet of pseudo random numbers is exchanged at the first frequency before changing to the next frequency and exchanging another packet of pseudo random numbers.
Since the attack apparatus generally includes filters (e.g., a low pass filter and a band pass filter) and mixers (e.g., a down converter and an up converter), the attack apparatus causes a delay in relaying a signal. In order for an attack by an attacking device to be undetected, the attacking device needs to retransmit the received signal without detectable delay. This makes it difficult for an attacking device to be detected. The attacking device may delay the signal by 500ns, which may spatially delay the signal by 500 feet (ft). In order for the attacking device to advance the transmission of the tone or start the transmission of the tone at the correct time, the attacking device may need to know the content being transmitted in advance. This is not possible. This is especially true when a heterodyne receiver is used to receive the relayed signal. The heterodyne receiver converts the packet/audio into an in-phase (I) -quadrature-phase (Q) domain and captures in the IQ domain. In the IQ domain, the phase difference is detected. If there is an attack, a delay caused by the attack may be detected in the IQ domain based on the phase difference. If the attacking device shortens the tone so that the corresponding synchronous access word arrives at the correct time, the timing and length of the CW tone will be incorrect and will be detected by the initiator.
In an embodiment, the initiator checks the received CW tone sent from the responder for: (i) a length relative to a start of a transmitted synchronous access word, (ii) a power (or amplitude) that is consistent prior to synchronous access and relative to the synchronous access word, and (iii) a pitch that is consistent throughout the synchronous access word. Consistent pitch may refer to consistent frequency, power level, amplitude, etc. In another embodiment, the start and end times of the synchronous access word relative to the start of the first CW tone of the transmitted packet may be known for a predetermined amount of time (e.g., in the range of ± 10 ns). Thus, if the start time and the end time are within a predetermined range of the start of the first CW tone of the packet, no attack occurs, otherwise an attack may occur.
As another example, the PLL of the initiator that transmits the tones may have 3 different tones that the PLL can generate on a given channel: a center tone, a high tone at a first frequency (e.g., 250KHz), and a low tone at a second predetermined frequency (e.g., -250 KHz). The transmitted tones may be selected and transmitted according to a predetermined agreed-upon random sequence and/or tone pattern. An agreement may be reached between the initiator and the responder. The PLLs of the initiator and the attacking device may not coincide with each other. The initiator may determine that an attack has occurred if there is a frequency difference between a signal transmitted by the initiator and a signal received in response thereto that is greater than a predetermined threshold.
In an embodiment, the responder is able to measure and respond with data with a phase delay detected by the responder for the received signal. This may be based on when the responder received the end CW tone of the packet from the initiator. The responder may measure the phase delay between (i) the end (or end) CW tone of a packet received from the initiator and (ii) the front end (or first master CW tone) of a packet transmitted by the responder in response to the packet received from the initiator. The initiator may calculate the total two-way round trip time for packets from the initiator to the responder and then back from the responder to the initiator.
In addition to detecting the delay of the signal, the initiator may also detect when the attacking device amplifies the signal (or tone). Amplification of the signal/tone may also delay transmission, which may be detected. During tone repetition at an attacking device, a tone may be distorted and/or another tone may be transmitted instead of the originally transmitted tone.
The above example allows more accurate distance measurement with a smaller number of packets, each having a synchronous access word and a CW tone. The synchronous access word protects the CW tone (and vice versa) from an attacking device modifying the CW tone without detection. Bidirectional randomized communication of both guard sync access words and CW tones is performed.
The PLL of the initiator as disclosed herein may be a phase-predictable PLL that allows the initiator to predict the phase of the signal when the frequency of the signal is changed. This may eliminate the need to check whether the timing of the CW tone sent by the initiator and the CW tone sent by the responder is correct. The responder may measure, for example, when the end CW tone from the initiator is received, determine the corresponding phase delay of the end CW tone relative to the front CW tone generated by the responder for the response signal, and send this information to the initiator along with the front CW tone. The initiator may then calculate a total round trip time based on the received information.
In an embodiment, the initiator is one of a vehicle or a portable access device and the responder is the other of the vehicle and the portable access device. The order in which the vehicle and portable access device transmit and respond is pseudo-randomly altered. In addition, the packet and/or tone signal may be transmitted in response and then may be used as an initiator packet and/or initiator tone signal. In one embodiment, the order in which the vehicle and portable access device transmit and respond does not change for a short period of time (e.g., the exchange period is less than the predetermined period of time) and changes for a long exchange period (e.g., the exchange period is greater than or equal to the predetermined period of time). The order may be switched periodically. In these examples, the bidirectional data is exchanged using antenna polarization diversity to provide correct timing measurements.
Processing is implemented to provide accurate measurements of the start and end points of the CW tone and the synchronous access word. Correlation and protocol module 3920 may maintain a circular queue of bits and lock to compare between the start and end times and lengths of the CW tone and the synchronous access word of a transmitted (initiator) packet and the start and end times and lengths of the CW tone and the synchronous access word of a received (responder) packet. The correlation and protocol module 3920 may interpolate at the locations of the zero crossings. Post-processing of the I and Q data associated with the synchronous access word may be performed for clock recovery for interpolation when the synchronous access word arrives. The I and Q data may have different switching/spin rates. Interpolation may be performed to determine where the center point of the transition will achieve the precise timing of clock recovery. To dial-in timing, multiple zero crossings may be detected and aligned. In addition, the I and Q data may be oversampled, as described further below, to best fit/align one or more bits.
Fig. 61 shows an antenna path determination system 6700 for a network device having a corresponding antenna module. The antenna module exhibits polarization diversity. In this example, two polarization axes for each antenna module are shown. Each antenna module includes a vertically oriented antenna and a horizontally oriented antenna. Showing possible channel vectors h VV、hVH、hHVAnd hHH. A ranging module 6710 is shown. Ranging module 6710 is based on channel vector hVV、hVH、hHVAnd hHHIn (1)A respective channel vector determines the range (or distance) between the corresponding antennas of the network device. The ranging module may perform a ranging algorithm to determine the rangeAndthe determined rangeAndis provided to a min module 6712, which min module 6712 determines a rangeAndwhich range is the shortest. The shortest path may be selected.
Each channel vector may be generated for one or more selected frequencies. When comparing, ranges may be generated for channel vectors of the same frequency or different frequencies. As an example, vectors may be generated for at least some of the 80 different tones with a frequency step of 1MHz between adjacent tones and within the industrial, scientific and medical (ISM) band of 2.4 GHz. The frequency associated with the shortest range may be selected. Other factors such as signal strength, amplitude, voltage, parameter consistency, etc. may also be considered in making this selection. This path selection may be performed by any of the initiators, responders, modules, network devices, etc. disclosed herein and used for round-trip timing measurements. This allows the best antenna path to be selected for the bi-directional packet and/or tone handshake to determine the round trip time.
Referring now to figures 38 and 62, there is shown an example radio model 6800 corresponding to the structure, function, and operation of BLE radio 3900 (and/or a modified version of BLE radio 3900) of figure 38, as well as RF channels and corresponding RF circuitry. The radio model 6800 may include a first sampling module 6802, a time offset module 6804, a gaussian low pass filter 6806, an integrator 6808, a first upsampler 6810, an amplifier 6812, a summer 6814, a modulator 6816, a second sampling module 6818, a phase and frequency offset module 6820, a first mixer 6822, a phase delay device 6823, a second mixer 6824, a phase delay module 6826, a second low pass filter 6828, a resampling module 6830, an arctangent module 6832, a differentiator 6834, a symbol determination module 6836, a bit pattern module 6838, a second upsampler 6840, a third upsampler 6842, a cross-correlation module 6844, and a peak detector 6846. Devices 6802, 6804, 6806, 6808, 6810, 6812 may represent examples of a transmitter portion of BLE radio 3900 or another BLE radio. Adder 6814 represents the channel between the radios: (i) another BLE radio; and (ii) BLE radios 3900 of devices 3907, 3906, 3908, 3932, and 3910. There may be a phase shift and frequency shift between the receiving BLE radio and the transmitting BLE radio because the receiving BLE radio may not be phase locked to the transmitting BLE radio. The devices 6816, 6818, 6820, 6822, 6824, 6828, 6830 correspond to the receiver portion of BLE radio and are associated with an RF sampling rate. Devices 6830, 6832, 6834, 6836, 6838 correspond to receiver portions and perform operations on baseband signals. The resampling module 6830 functions as an analog-to-digital converter. Devices 6840, 6842, 6844, and 6846 also correspond to receiver sections and are associated with interpolation to determine phase.
When the bit stream is recovered, the zero crossing of the reconstructed signal from differentiator 6834 may be determined. There may be a large amount of jitter at the zero crossing, which negatively affects the time of flight determination based on the timing of the zero crossing. A small amount of jitter has a negative impact on the determination of the transmission time and the reception time.
The upsamplers 6840, 6842 and cross-correlation module 6844 are implemented to reduce jitter associated with sampling and zero-crossing determination. The upsamplers 6840, 6842 perform signal processing to interpolate and inject data points between existing received data points to provide finer temporal resolution.
In one embodiment, the transmitted bit stream is known in advance by the BLE receiver and provided to the upsampler 6842 as shown by arrow 6843. In this example, the symbol determination module 6836 and the bit pattern module 6838 are not included. In another embodiment, the transmitted bitstream is unknown and includes a symbol determination module 6836 and a bit pattern module 6838 and upsampling 6842 provides an estimated bitstream. As an example, the transmitted bitstream may be an access address indicating what device is transmitting. The estimated bit stream may be determined based on a reference. For example, the reference may be a preamble and/or a bit sequence received before the bit stream is estimated. The preamble and/or the bit sequence provide a reference in time, based on which the estimated bit stream can be generated. The estimated bit stream is generated based on the known clock frequency of the transmitter and is associated with the clock frequency of the transmitted signal and the receiver.
The cross-correlation module 6844 performs cross-correlation between the outputs of the upsamplers 6840, 6842 and/or cross-correlation between the upsampler 6840 and the output of the bit pattern module 6838. Cross-correlation is performed to match the envelopes of the signals provided to the cross-correlator and determine the phase difference. The cross-correlation may include: the multiplication of the output signals is performed, including taking the products of the corresponding data points of the two output signals and summing the products. The product-sum summation process is iterated while incrementally shifting one of the outputs relative to another of the outputs by one data point in time for each iteration to provide values for a plurality of resulting product-sums. The value of the largest product sum among the values of the product sums means: when the two outputs are synchronized (or aligned), the waveforms are made to match and align in time. Based on this information, a phase offset (or difference) between the two outputs is determined.
The cross-correlation has an improved resolution due to the upsampling performed by the upsamplers 6840, 6842. The cross-correlation module 6846 performs correlation with a signal having a finer resolution than the originally received signal to obtain a finer interpolation of the arrival times of the received packets in the received signal. Higher correlation resolution reduces the signal-to-noise ratio and bit length of the message and may include interpolation at a finer resolution. The phase offset may be used for time-of-flight determination as described herein. The peak detection module 6846 evaluates the results of the cross-correlations and indicates (i) when a time-matching peak occurs, and/or (ii) a phase shift. In one embodiment, the cross-correlation module 6844 receives digital values and the peak detection module 6846 determines whether the cross-correlation output (or the value of the product-sum) has reached a predetermined threshold. If the predetermined threshold has been reached, the peak detection module indicates "signal found" and determines the phase.
In one embodiment, the output of the upsampler 6840 is provided to the sign determination module 6836 and the cross-correlation module 6844, and does not include the upsampler 6842. In this example, the output of the bit pattern module 6838 is provided directly to the cross-correlation module 6844.
The apparatus of fig. 38 and 62 is further described with respect to the method of fig. 63. Although the following operations of fig. 63 are described primarily with respect to the implementations of fig. 2-6, 11, 14, and 38, these operations may be readily modified to apply to other implementations of the present disclosure. These operations may be performed iteratively.
The method may begin at 6900. At 6902, the sampling module 6802 of the first network device (e.g., a network device implemented in a vehicle as part of an in-vehicle system or portable access device) receives a bitstream to be transmitted from the processing module 3922. The sampling module 6802 samples the bitstream.
At 6904, a time offset module 6804 receives the output of the sampling module 6802 and may introduce a time offset (or delay). The sampling module 6802 and the time offset module 6804 may be implemented by a protocol module 3924. At 6906, a gaussian Low Pass Filter (LPF)6806 receives the output of the time offset module 6804, which may comprise a filtered bit stream, and converts the square wave to a sine wave. The operation of gaussian LPF 6806 may be implemented by GFSK modulator 3926. At 6908, an integrator 6808 integrates the output of gaussian LPF 6806 and may be implemented by D/a and low pass filter 3928. Example signals 7000, 7002, 7004 from the sampling module 6802, the gaussian LPF 6806, and the integrator 6808, respectively, are shown in fig. 64A.
At 6910, the upsampler 6810 upsamples the output of the integrator 6808 to include additional points sample by sample. The upsampler 6810 may be implemented by an upconverter 3930. At 6912, amplifier 6812 provides frequency offset gain. In 6914, sampling module 6818 receives RF tones that may be provided by PLL 3940. The output of the sampling module 6818 is provided to both the modulator 6816 and the phase and frequency offset module 6820. At 6916, modulator 6816 modulates the output of sampling module 6818 based on the output of amplifier 6812 to provide an initiator signal. The modulator 6816 may be implemented at least in part by an upconverter 3930.
At 6918, the initiator signal from modulator 6816 may be provided to the power amplifier 3932 and sent to the second network device. The second network device may be a network device implemented in the vehicle as part of an in-vehicle system or a portable access device. The initiator signal may be any of the following disclosed herein: an initiating tone signal, a signal transmitted by the master device, etc.
At 6920, the low noise amplifier 3910 receives a response signal in response to the initiator signal. The response signal may include gaussian noise included in the received response signal, as represented by summer 6814. At 6922, mixers 6822, 6824 receive the response signal from the low noise amplifier 3910 and downconvert the response signal to an in-phase (I) baseband signal and a quadrature-phase (Q) baseband signal. The quadrature phase baseband signal may be phase delayed by 90 ° via a phase delay device 6823. This may be implemented at downconverter 3912.
LPF6828 filters the baseband signal and removes high frequency components at 6924. LPF6828 may include a plurality of LPFs; there is one LPF per downconverted signal. LPF6828 may be replaced by and/or implemented by a band pass filter and amplifier 3914. At 6926, the resampling module 6830 samples the filtered baseband signal using the sample dither. The resampling module 6830 may be implemented by the a/D converter 3916. Example signals 7006, 7008 from the resampling module 6830 are shown in fig. 64B.
At 6928, the arctangent module 6832 determines the arctangent of the baseband signal to generate an arctangent signal. An example signal 7010 from the arctan module 6832 is shown in fig. 64C. At 6930, a differentiator 6834 differentiates the arctan signal from the arctan module 6832. An example signal 7012 from differentiator 6834 is shown above the original gaussian filtered signal 7002 in fig. 64D.
At 6932, a sign module 6836 performs a sign function and determines a sign of the output of the differentiator 6834. At 6934, the bit pattern module 6838 determines an idealized (or reference) bit pattern based on the output of the sign module 6836. After the operations of the low pass filter 6828 and the arctan module 6832 have been applied, an idealized bit pattern is obtained to match the bit pattern from the gaussian LPF 6806 or other bit pattern to the received bit pattern. This is done so that the upsampled values resemble noise-free resampled data.
At 6936, upsamplers 6840, 6842 upsample the outputs of differentiator 6834 and bit pattern module 6838, respectively. At 6938, the outputs of the upsamplers 6840, 6842 are correlated by a cross-correlation module 6844 to generate a correlation signal. The devices 6832, 6834, 6836, 6838, 6844, 6842 may be implemented by a demodulator 3918. At 6940, the peak detector 6846 determines the phase of the resulting correlation signal from the cross-correlation module 6844. The cross-correlation module 6844 and the peak detector 6846 may be implemented by the correlation and protocol module 3920. In one embodiment, the peak detector 6846 is implemented as a 3-point parabolic peak interpolator (3point parabolic peak interpolator) above the upsampled cross-correlation module 6844. Two points near (within a predetermined distance from) the detected peak are selected and a three-point parabolic interpolation of the up-sampled result is obtained.
At 6942, distance, position, round trip time, and/or other parameters are determined based on phase (or 3-point parabolic interpolation of the upsampled results). The distance may be a distance between the first network device and the second network device. The location may be a location of the second network device relative to the first network device. The round trip time may be a time when the initiator signal travels to the second network device and the first network device receives the response signal, including a time when the second network device generates the response signal after receiving the initiator signal.
At 6944, the processing module 3922 may determine whether an extended range relay attack has occurred based on the phase, distance, location, round trip time, and/or other parameters determined at 6942. If an extended range relay attack has occurred, operation 6946 may be performed, otherwise the method may end 6948. In 6946, the processing module 3922 performs a countermeasure, such as any of the countermeasures disclosed herein.
The above-described operations of fig. 35, 36, 45, 54, and 63 are intended to be illustrative examples. These operations may be performed sequentially, synchronously, simultaneously, continuously, during overlapping time periods, or in a different order, depending on the application. Additionally, no operation may be performed or skipped depending on the implementation and/or order of events.
There is a variation in the transmission timing between (i) the time at which the generated waveform arrives at the antenna to be transmitted and (ii) the corresponding time measured by the timer. Factors that may contribute to this include clock domain crossing, clock cycle variation, power amplifier propagation delay due to power amplifier gain settings, temperature and process propagation delay. Process, temperature and amplifier gain setting variations can be calibrated out of timing measurements.
A second BLE device (e.g., BLE device (or radio) 3900B) similar or identical to the first BLE device (e.g., BLE device (or radio) 3900A of figure 38) may be added and implemented in the vehicle to represent a reflective (or responder) device as shown in figure 49. Each BLE radio 3900 may be implemented on a separate system on a chip (SoC). The first BLE radio 3900A may transmit an initiator signal that may be received by a receiver portion of the second BLE device.
Time T1 may be generated for the time at which the first bit stream is generated and/or provided to the protocol module 3924A of the first BLE radio 3900A to generate the initiator signal determined by timer 3938A to be transmitted from the first BLE radio 3900A. The time T2 may be the time at which the correlation and protocol module 3920B of the second BLE radio 3900B received the first bitstream as determined by the timer 3938B. The first calibration constant CAL1 may be set equal to or determined based on the difference between the time that the timer 3938A detects the generation of the first bit stream and the time that the corresponding initiator signal is transmitted from the antenna 3907A. The second calibration constant CAL2 may be set equal to or determined based on the difference between the times at which the timer 3938B detects the reception of the first bitstream at the correlation and protocol module 3920B. The time of flight for the first bit stream from protocol module 3924A to correlation and protocol module 3920B is (T2-CAL2) - (T1-CAL 1).
Similarly, time T3 may be generated for generating and/or providing a second bit stream corresponding to the first bit stream to protocol module 3924B to generate a response signal to be transmitted from second BLE radio 3900B as determined by timer 3938B. A response signal is generated in response to the initiator signal. Time T4 may be the time at which correlation and protocol module 3920A receives the second bitstream as determined by timer 3938A. The third calibration constant CAL3 may be set equal to or determined based on the difference between the time that the timer 3938B detects the generation of the second bit stream and the time that the corresponding response signal is transmitted from the antenna 3907B. The fourth calibration constant CAL4 may be set equal to or determined based on the difference between the times at which the timer 3938A detects the reception of the second bitstream at the correlation and protocol module 3920A. The time of flight for the second bit stream from protocol module 3924B to correlation and protocol module 3920A is (T4-CAL4) - (T3-CAL 3). The distance between the average time of flight \ first and second BLE radios 3900 may be determined using equations 33-35, where equation 33 is based on equation 32 and takes into account the timing variations described above and thus includes corresponding calibration values.
Mean time of flight [ [ (T)2-T1)+(T4-T3)]/2 (32)
Collect similar information and add calibration values:
mean time of flight [ [ (T)2-CAL2-T1+CAL1)+(T4-CAL4-T3+CAL3)]/2 (33)
Distance ═ c [ (T)4-CAL4-T1+CAL1)+(T3-CAL3-T2+CAL2)]/2 (34)
Separate calibration from time measurement:
distance ═ c [ (T)4-T1)-(T3-T2)+(CAL1-CAL4+CAL2-CAL3)]/2 (35)
The timer 3938B may start with a handling protocol and/or perform fine tuning of the transmission time at the second BLE radio 3900B to minimize reporting on T2-T3.
The PLLs 3940A, 3942A of the first BLE radio 3900A may be implemented as a single PLL. Similarly, the PLLs 3940B, 3942B of the second radio 3900B may be implemented as a single PLL. The two PLLs allow the hardware of the transmit and receive sections to be implemented on the same SoC, while allowing the transmit time of the initiator signal to be captured using the same BLE circuitry used to capture the receive time of the response signal.
In accordance with the present teachings, a multi-axial polarized RF antenna assembly includes: a circularly polarized antenna comprising a conductive loop body having an inner bore; a circular isolator connected to the conductive ring; and a linearly polarized antenna connected to and extending outwardly from the circularly polarized antenna and the circular isolator. A linearly polarized antenna includes a sleeve and a conductive element extending through the sleeve. The linearly polarized antenna extends orthogonal to the radius of the circularly polarized antenna.
In accordance with the present teachings, a multi-axis polarized RF antenna may include a conductive element as a wire.
In accordance with the present teachings, the sleeve may be formed of polytetrafluoroethylene and the conductive element may be formed of copper.
In accordance with the present teachings, a linearly polarized antenna may be configured to extend downwardly from a circularly polarized antenna when in use.
According to the present teachings, the circularly polarized antenna may be a 2-axis antenna and the linearly polarized antenna may be a single-axis antenna.
According to the present teachings, the multi-axis polarized radio frequency antenna may further comprise a ground plane, and the circular isolator may be disposed on the ground plane, between the conductive element and the ground plane, and between the circular polarized antenna and the ground plane.
According to the present teachings, a circularly polarized antenna may include two feed points that are phase-offset by 90 ° and configured to receive signals that are 90 ° out of phase with each other.
In accordance with the present teachings, a vehicle may include a body and a roof that includes a multi-axial polarized RF antenna assembly. The multi-axis polarized RF antenna assembly may be oriented in the vehicle roof such that the linearly polarized antenna extends downward from the circularly polarized antenna.
In accordance with the present teachings, a vehicle may include a multi-axial polarized RF antenna assembly. The multi-axial polarized RF antenna assembly may include a first multi-axial polarized RF antenna assembly configured to be implemented in a vehicle and a second multi-axial polarized RF antenna assembly configured to be implemented in a vehicle, and the second multi-axial polarized RF antenna assembly includes: a second circularly polarized antenna comprising a second conductive loop body having a second inner bore; a second circular isolator connected to the second conductive ring body; and a second linearly polarized antenna connected to and extending outwardly from the second circular isolator. The second linearly polarized antenna may include a sleeve and a conductive element extending through the sleeve of the second linearly polarized antenna. The second linearly polarized antenna may extend orthogonal to a radius of the second circularly polarized antenna, and the access module is connected to the first and second multi-axis polarized RF antenna assemblies and configured to communicate with the portable access device via the first and second multi-axis polarized RF antenna assemblies.
At any instant in time, at least one of the linearly polarized antenna or the first multi-axis polarized RF antenna assembly is not cross-polarized with the antenna of the second multi-axis polarized RF antenna assembly in accordance with the present teachings.
According to the present teachings, the access module may be configured to perform a passive entry passive start operation or a mobile phone i.e. key operation, including: transmitting and receiving radio frequency signals via a first one of the multi-axis polarized RF antenna assemblies and a second one of the multi-axis polarized RF antenna assemblies.
According to the present teachings, the access module may be configured to grant access to the vehicle based on the radio frequency signal.
In accordance with the present teachings, the access module may be configured to execute an algorithm to determine which antenna pair having a first one of the multi-axis polarized RF antenna assemblies and a second one of the multi-axis polarized RF antenna assemblies is to be used for communicating with the portable access device.
According to the present teachings, the portable access device may be a key fob or a cellular telephone.
In one embodiment, the BLE radio of a cellular telephone is used as a mobile telephone, i.e., key system, as described herein to micro-locate the position of the mobile telephone relative to a set of receiving sensors. The sensor is located within the vehicle. Sensors are used to detect whether the mobile phone is close enough to the vehicle to allow access to the vehicle (e.g., unlock a door of the vehicle and/or start the vehicle). The vehicle's access module uses the angle of arrival (AOA) principle. By knowing the angle of arrival of the signals transmitted from the BLE radio to at least two independent sensors in the vehicle, bidirectional measurements of the source (i.e., the BLE radio) can be made on the 2D plane. In this case, a phased antenna array is used to measure the angle of arrival of the incoming signal. A phased antenna array includes multiple antennas that receive and transmit signals. Each sensor in the vehicle includes one or more antennas. Each sensor may be a phased array sensor comprising: a three-antenna interleaved Circular Polarization (CP) receiver having a single radio receiver; a six antenna interleaved Linearly Polarized (LP) receiver having a single radio receiver; a three antenna interleaved CP receiver with a single radio receiver; a three-antenna interleaved printed antenna CP receiver with a single radio receiver.
The access module detects the direction of the incident AOA signal taking into account multipath effects. As an example, two sinusoidal RF signals transmitted and arriving at the sensor array are summed together in the antenna of the sensor array. The sum of the two sinusoidal RF signals is a sine wave having a phase and amplitude that differs depending on the phase angle and amplitude of the two source sine waves. Mathematical models used to predict AOA direction may indicate errors. In any dynamic multipath environment, such errors can be very large and unstable. To prevent such errors, the musical algorithm disclosed herein may be used to identify the source signal and potentially strong multipath reflected signals. The direct path signal is accurately tracked from the cellular telephone. The tracking identifies any additional reflected signal(s). The reflected signal may be identified and discarded.
The access module and control module disclosed herein may implement any of the musical algorithms mentioned and/or disclosed herein. Direction-finding methods can be roughly classified into two categories, sometimes referred to as classical methods and modern methods. Classical methods include various beamforming methods. Modern methods are often referred to as subspace methods. The music algorithm is classified as a super-resolution parameter estimation algorithm using a subspace separation method. The subspace approach may require a specific array geometry for two identical but physically displaced arrays. Other methods include maximum likelihood estimation and beamforming.
Fig. 70 shows a side view of a plurality of antennas 7000 in the array, illustrating the angle of arrival θ. The antenna array may be referred to as an array manifold. Each antenna 7000 may be identically and/or similarly constructed as any of the antennas disclosed herein. In one embodiment, the one or more antennas are quadrifilar helix antennas.
The music algorithm uses a model of the array manifold that describes the response of the array manifold to one or more incident AOA signals. A uniform linear array of antennas (ULA) may be defined as shown in fig. 70, where M is the index of antennas in the array starting from 1, M is the total number of antennas, d is the spacing between antenna elements, and θ is the angle of the incident signal. The response of array element m to incident signal s can be represented by equation 37, where r is the received signal, a is the complex array manifold response, s is the source signal, stated m is the index number of the antenna element of interest, stated θ is the physical angle of the incident source signal, λ is the wavelength of the signal, and n (t) represents the noise in the receiver channel. This shows the effect of phase delay as a function of the physical position of the receiving sensor array elements, with a complete 180 ° phase shift at d ═ λ/2. It also accounts for the phase shift as a function of the angle of incidence theta.
For 1<m<M antennas for the antenna at an angle of incidence thetanGiven a source signal n, an array steering vector amDefined by equation 38. This assumes an amplitude response of 1 at each antenna and an ideal phase response of 1 for the ULA relative to the antenna.
For the N incident signals, the received signal r (t) yields the sum of the source signals through the array manifold and can be represented by equation 39.
In vector notation, the array manifold response parameters a and A are defined by equations 40 and 41. Vector a describes the array response of each element to a single source signal N, and a describes the response of all M array elements to all N source signals, and is an MxN matrix, where M and N may each be an integer greater than or equal to 2. The N source signals sampled at time instant t are represented as Nx1 vector s (t), as shown in equation 42.
S(t)=[s1(t),s2(t),...sN(t)]T(42)
Equation 43 may be used to map the N source tones at different source angles of arrival represented in signal s (t) at a given time t through the antenna array response manifold model a to a received (measured) data vector r (t), where the channel noise is N (t), where r (t) is the Mx1 vector of received data at each antenna element.
r(t)=AS(t)+n(t) (43)
This mathematical structure of the array manifold model is used to derive musical algorithms and may also be used for simulation and modeling of the test environment.
FIG. 71 shows an example AOA method that includes using a music algorithm. Although the operations are primarily described as being performed by an access module of a vehicle (such as one of the access modules disclosed herein), the operations may be performed by a control module of a portable access device. Note that the H operator indicates a Hermitian transpose or conjugate transpose operation. The method may begin at 7400. At 7402, the access module collects T analytic signal samples from each antenna simultaneously, e.g.As shown.
The covariance matrix estimate is calculated according to equation 44 and an example of the covariance is shown in fig. 72. Explained below, each arrow represents the covariance between the antenna numbers listed in the X-axis and the Y-axis at the bottom of the arrow. The upper arrow indicates the covariance (c) of antenna number 1 with respect to antenna number 212) And the left arrow indicates the covariance of antenna number 2 with respect to antenna number 1 (c)21) It is c12Complex conjugation of (a). The direction of the arrow is a complex planar representation of magnitude and direction (X-axis is the real axis, and Y is the real axis)The axis is the imaginary axis).
Note that the diagonal (top left to bottom right) represents the autocovariance, which is the unit magnitude and 0 imaginary value. Further, note that: the matrix is Hermetian, which means that c is valid for all i and j ijAnd c, wherein is a complex conjugate. Therefore, all useful information is contained in (i) c12、c23And c13Or (ii) c21、c32And c31Middle (upper right or lower left corner, excluding the diagonal from upper left to lower right). This results in the potential to save data storage and reduce transmission size.
At 7406, the access module uses Singular Value Decomposition (SVD) or another eigenvalue decomposition technique and computes the MxM matrix U as shown in equation 45.
Estimating in covariance matrixAfter eigenvalue decomposition, the resulting complex eigenvector is provided, an example of which is shown in fig. 73. Fig. 73 shows a feature vector visualization with an array manifold response at 35 °. Fig. 74 shows a feature vector visualization with an array manifold response at 0 °.
As in fig. 72, the magnitude and direction of the arrows indicate the real and imaginary components of each point corresponding to the real part on the X-axis and the imaginary part on the Y-axis, respectively. Solid and short dashed arrows represent a 3x3 array of feature vectors. The vector columns (X-axis) are ordered by eigenvalue of the eigenvector from large (left) to small (right). Thus, the leftmost column number 1 represents the signal subspace, while columns 2 and 3 represent the noise subspace.
At 7408, the access module estimates or otherwise determines the number of incident signals N. At 7410, the access module divides the matrix U into an MxN signal subspace matrix Sum noise subspace estimationM (M-N) matrixTo satisfy equation 46.
Along with the feature vector, the array manifold response at the angle of interest (35 °) is shown by the long dashed arrow. This is derived from equation 40.
At 7412, the access module calculates the music spectrum P (θ) for the range of θ of interest at a predetermined resolution, as shown in equation 47.
At this point, the noise subspace eigenvector of the covariance matrix estimate should be perfectly orthogonal to the array manifold response. The result of the denominator of equation 47 is a very small number relative to the result at different test angles θ.
FIG. 74 presents the same information as FIG. 73, except that the array manifold response is shown at AOA of 0. Note that the feature vector remains unchanged, since the feature vector is derived from the measured data. The array manifold response is rotated and shows the expected response to the incoming radio signal, which means that there is no phase shift at any antenna element. In this case, the result of the denominator of equation 47 is a much larger value than that achieved in the case of fig. 73.
At 7414, the access module performs a peak search on P (θ) to determine an angle of arrival. The value of θ at the maximum value of P (θ) is the angle of arrival of the N incident signals.
In the range of-90 to +90After processing equation 47, the resulting music power spectrum P (θ) is shown in fig. 76 for a source signal AOA of 35 °. Note that the test at 35 deg.CThere is a clear peak at AOA. The actual angle is indicated by the vertical dashed line.The resolution of (2) is 1 deg..
A covariance smoothing method may be used. As an example, a forward-backward method may be used. The forward-backward method is implemented using equations 48 and 49, whereIs the modified covariance matrix estimate and J is the MxM inverse identity matrix (transfer matrix).
An effective number of coherent tones that can be resolved isAnd (4) a source. For a 3 antenna array, up to 2 coherent tones may be resolved. The method may be used for a three-antenna phased array of phased antenna array receiver boards. The method may end at 7416.
As another example, a spatial smoothing method may be used. The spatial smoothing method is a technique that involves subdividing the array into a number of sub-arrays and averaging together the covariance matrix results of the sub-arrays. This results in an effective reduction in the number of antenna array elements.
A forward-backward spatial smoothing (FBSS) method may be used and combined with the forward-backward method. It also reduces the number of required antenna elements. As yet another example, the toeplitz finish method may be used and applied to NLAs.
Variations of the music algorithm may be implemented. Of MUSIC algorithms known as Root-MUSICA derivative can be used on the ULA to find the incident signal AOA without calculating the result at each potential angle. This reduces the required computational power. The reduction in computational complexity comes from operations 7412, 7414 that do not require the execution of a musical algorithm, included inThe music spectrum is computed over a large set of values and the peak(s) of the result are found.
Another example derivation, known as Spectral-MUSIC, is the generalized version of Root-MUSIC, which can be applied to any array geometry, but is typically applied to wideband non-coherent sources. Yet another derivation, referred to as Smooth-MUSIC, refers to various methods of smoothing the covariance matrix in the MUSIC algorithm and is applied between operations 7404 and 7406 of fig. 71.
Another example derivation, known as the CLEAN method, involves reconstructing a model of the source signal from a known array manifold once the source signal is identified in a given direction. The reconstructed signal model is subtracted from the measured incident signal to remove the incident signal, thereby "cleaning up" the measurement data of the undesired source signal and allowing other sources to be viewed.
One problem that arises when implementing musical algorithms on non-ideal antenna arrays is: two coherent sources with forward-backward covariance smoothing can result in erroneous position measurements. Standard array calibration techniques cannot solve this problem because the covariance matrix itself can lead to erroneous subspace separation. To address this problem, a variation of the CLEAN method is performed for multiple coherent sources and includes: identifying a source signal using a music algorithm; using the CLEAN method to remove the source signals one at a time using the calibrated array manifold; force the source signal position to shift (not at the originally measured position) and recalculate the AOA direction of the remaining signal; operations 7404 and 7406 of FIG. 71 are repeated to verify convergence to a new set of incident angles of arrival if different from the original angles of arrival; and optionally replace operation 7402 of fig. 71 with a priori knowledge from the system. For example, in tracking the location of the source signal, it can be assumed that the AOA does not vary greatly between subsequent readings.
Fig. 76 shows an antenna selection system 7600, which includes an antenna 7602, a switch 7604, and a radio receiver 7606. The radio receiver 7606 selects one of the antennas from which to receive a signal via the switch 7604. Antenna selection system 7600 can be implemented in any of the systems disclosed herein. In one embodiment, the antenna selection system 7600 is implemented in a vehicle and the access module disclosed herein controls operation of the radio receiver 7606.
Fig. 77 illustrates an example reconstruction method for reconstructing IQ data. The interleaved data is interpolated to form a matrix of received data r (t) for use in the musical algorithm. The reconstruction method may be performed by any of the access modules disclosed herein. The signal reconstruction method may begin at 7700.
At 7702, the access module converts the analysis IQ sample vector r to a phase angle vector using an arctan functionAt 7704, the access module creates a time vector t corresponding to the sample vector r based on the data sample rate.
At 7706, the access module discards samples taken around the antenna switching time. At 7708, the access module spreads each repeated portion of the data point in steps of π. At 7710, the access module measures the average slope. This is the average frequency of the sinusoid.
At 7712, the access module, for each antenna: a) finding an intercept of a first iteration of the sampled data; b) projecting a location of a next iteration of the sampled data; c) determining an average difference between the expected and measured actual positions; d) plus or minus 2 pi; e) repeating operations c and d, including repeating the determination of the average difference and the addition or subtraction of 2 π until the average difference is less than π; f) finding the average slope of all already aligned points; g) the operations b-g are repeated using the new slope for the next signal.
At 7714, the access module measures the standard deviation of the average slope for each antenna.
At 7716, if the standard deviation is above the threshold, the access module checks which antenna may have inaccurate alignment by selecting antenna i based on equation 50
At 7718, the access module repeats operations 7712- > 7718 for the antenna selected at 7716 until the low standard deviation or maximum retry counter expires.
At 7720, for each antenna m, the access module interpolates straight-line points over the original time vector t to obtain a reconstructed phase angle vectorThis may be based on the phase angle vector determined at 7702
At 7722, the access module recreates IQ sample vectors for each antenna m using equation (51) Where g is the average magnitude of a significant subset of the original sample vector r. After operation 7722, the method may end at 7724.
In one embodiment, the above method is implemented in a vehicle access system and/or PAK system having a circularly polarized antenna, as disclosed herein. Signals are received at a circularly polarized antenna. As described above, IQ data is determined based on the received signal, and the angle of arrival is determined using a music algorithm.
Fig. 78A-78C show a vehicle 7800 illustrating an example placement of a sensor 7802 that may be implemented as part of any PAK system disclosed herein and may be connected to any access module disclosed herein. Fig. 78C illustrates an example bounce reflection and corresponding path of a signal sent from a key fob 7804 or other portable access device and detected at a sensor 7802. In this example, sensor 7802 is located high and centered on vehicle 7800. The sensor 7802 may be located, for example, in a roof 7803 of the vehicle 7800. The sensor 7802 is positioned to cause multiple bounce paths of the transmitted signal before the transmitted signal is received at the sensor 7802. For purposes of illustration, the key fob 7804 is shown as being low relative to the vehicle, but may be located at a higher position.
Fig. 79A-79C show a vehicle 7900 illustrating another example placement of sensors 7902. Fig. 79C illustrates an example bounce reflection and corresponding path of a signal transmitted from key fob 7904 or other portable access device and detected at sensor 7902. In this example, the sensor 7902 is located low and in the center of the vehicle 7900. The sensor 7902 may be located in the floor 7903 or center console 7905 of the vehicle. The sensor 7902 is positioned to cause multiple bounce paths of the transmitted signal before it is received at the sensor 7902. For purposes of illustration, key fob 7904 is shown as being low relative to the vehicle, but may be located at a higher position.
In one embodiment, carrier phase based ranging is implemented using a musical algorithm or the like to determine the angle of arrival of the signals transmitted by the key fobs 7804, 7904. This may include eigenvalue decomposition. The distance between the key fob 7804, 7904 and the vehicle 7800, 7900 is determined based on the angle of arrival. Access is granted when the key fob 7804, 7904 is within a predetermined distance of the vehicle 7800, 7900. Although there is little likelihood of line of sight, there is a high likelihood that the transmitted signal bounces multiple times and reaches each of the sensors 7802, 7902 along multiple paths. This allows the corresponding access module to determine whether the key fob 7804, 7904 is near the vehicle 7800, 7900. Multipath signal processing is performed on top of carrier phase based ranging. This may include time-of-flight signal processing as described above, for example with respect to fig. 37, 52-56, and 62. As an example, an access module of vehicle 7800, 7900 may unlock a door of vehicle 7800, 7900 when key fob 7804, 7904 is within a predetermined distance of vehicle 7800, 7900.
Ranging on indirect and reflected paths can be performed using ranging based on BLE carrier phase by forcing the indirect signaling path and swapping a predetermined number of tight transmit tones and finding a characteristic value. A system with fewer sensors (referred to as anchors) can be used by placing the anchors so that the signal follows primarily an indirect path rather than a direct line-of-sight path.
In one embodiment, the RSSI of the transmitted signal is determined to determine whether the key fob 7804, 7904 is inside or outside the vehicle 7800, 7900. If the key fob 7804, 7904 is outside the vehicle, carrier phase based ranging with eigenvalue decomposition is performed to determine if the key fob 7804, 7904 is within a predetermined distance of the vehicle 7800, 7900.
The above description is illustrative in nature and is not intended to limit the present disclosure, application, or uses. The broad teachings of the present invention can be implemented in a variety of different forms. However, the disclosure includes particular examples, and the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims. It should be understood that one or more steps within a method may be performed in a different order (or simultaneously) without altering the principles of the present disclosure. Furthermore, although each of the embodiments is described above as having certain features, any one or more of those features described with respect to any embodiment of the present disclosure may be implemented in and/or combined with the features of any other embodiment, even if the combination is not explicitly described. In other words, the described embodiments are not mutually exclusive and substitutions of one or more embodiments with one another are still within the scope of the present disclosure.
Various terms are used to describe spatial and functional relationships between elements (e.g., modules, circuit elements, semiconductor layers, etc.), including "connected," joined, "" coupled, "" adjacent, "" beside … …, "" over … …, "" over … …, "" under … …, "and" arranged. Unless explicitly described as "direct," when a relationship between a first element and a second element is described in the above disclosure, the relationship may be a direct relationship in which no other intermediate element exists between the first element and the second element, but may also be an indirect relationship in which one or more intermediate elements (spatially or functionally) exist between the first and second elements. As used herein, the phrase "at least one of A, B and C" should use non-exclusive logic OR be construed to mean logic (a OR B OR C), and should not be construed to mean "at least one of a, at least one of B, and at least one of C. "
In the drawings, the direction of an arrow generally indicates the flow of information (such as data or instructions) of interest to the drawing, as indicated by the arrow. For example, when element a and element B exchange various information, but the information sent from element a to element B is related to the illustration, an arrow may point from element a to element B. This one-way arrow does not mean that no other information is sent from element B to element a. Further, for information sent from element a to element B, element B may send a request or receipt acknowledgement for the information to element a.
In this application, including the definitions below, the term "module" or the term "controller" may be replaced with the term "circuit". The term "module" may refer to, may be part of, or may include: an Application Specific Integrated Circuit (ASIC); digital, analog, or analog/digital hybrid discrete circuits; digital, analog, or analog/digital hybrid integrated circuits; a field-programmable gate array (FPGA); processor circuitry (public, private, or grouped) that executes code; memory circuitry (shared, dedicated, or group) that stores code executed by the processor circuitry; other suitable hardware that provides the described functionality; or a combination of some or all of the above, such as a system on a chip.
A module may include one or more interface circuits. In some examples, the interface circuit may include a wired or wireless interface connected to a Local Area Network (LAN), the internet, a Wide Area Network (WAN), or a combination thereof. The functionality of any given module of the present disclosure may be distributed among multiple modules connected via interface circuits. For example, multiple circuits may allow for load balancing. In a further example, a server (also known as remote, or cloud) module may accomplish part of the functionality on behalf of a client module.
The term code, as used above, may include software, firmware, and/or microcode, and may be programs, routines, functions, classes, data structures, and/or objects. The term "shared processor circuit" encompasses a single processor circuit that executes some or all code from multiple modules. The term "set of processor circuits" encompasses processor circuits that execute some or all code from one or more modules in conjunction with additional processor circuits. References to multiple processor circuits encompass multiple processor circuits on discrete die, multiple processor circuits on a single die, multiple cores of a single processor circuit, multiple threads of a single processor circuit, or a combination of the foregoing. The term "shared memory circuit" encompasses a single memory circuit that stores some or all code from multiple modules. The term "banked memory circuit" encompasses memory circuits that store some or all code from one or more modules in conjunction with additional memory.
The term "memory circuit" is a subset of the term "computer-readable medium". The term "computer-readable medium" herein does not encompass transitory electrical or electromagnetic signals propagating through a medium (such as on a carrier wave); the term "computer-readable medium" may thus be considered tangible and non-transitory. Non-limiting examples of a non-transitory tangible computer-readable medium are non-volatile memory circuits (such as flash memory circuits, erasable programmable read-only memory circuits, or masked read-only memory circuits), volatile memory circuits (such as static random access memory circuits or dynamic random access memory circuits), magnetic storage media (such as analog or digital magnetic tapes or hard drives), and optical storage media (such as CDs, DVDs, or blu-ray discs).
The apparatus and methods described in this application may be partially or completely implemented by a special purpose computer, which is created by configuring a general purpose computer to perform specific functions contained in a computer program. The functional blocks, flowchart components, and other elements described above serve as software specifications that can be interpreted as a computer program by a routine work of a technician or programmer.
The computer program includes processor-executable instructions stored on at least one non-transitory tangible computer-readable medium. The computer program may also comprise or rely on stored data. A computer program can encompass a basic input/output system (BIOS) that interacts with the hardware of a special purpose computer, a device driver that interacts with a specific device of a special purpose computer, one or more operating systems, user applications, background services, background applications, and the like.
The computer program may include: 1. description text to be parsed, such as HTML (hypertext markup language), XML (extensible markup language), or json (javascript Object notification); (ii) assembling the code; (iii) object code generated by a compiler from source code; (iv) source code executed by the interpreter; (v) source code for compilation and execution by a just-in-time compiler, and so on. By way of example only, source code may be written using syntax from the following languages: C. c + +, C #, Objective-C, Swift, Haskell, Go, SQL, R, Lisp, Fortran、Perl、Pascal、Curl、OCaml、HTML5 (5 th edition of HyperText markup language), Ada, ASP (Active Server Pages), PHP (PHP: Hypertext Preprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Hawkup, Gaizu, Hawkup, Gaizu, Hawkup, Gaizu, Gaiz,VisualLua, MATLAB, SIMULINK and
all elements recited in the claims are not intended to be means plus function elements within the meaning of 35u.s.c. § 112(f), unless an element is explicitly recited using the phrase "means for … …" or, in the case of method claims, using the phrases "operation for … …" or "step for … …".
Claims (18)
1. An access system for a vehicle, the access system comprising:
a receiver configured to receive a signal transmitted from a portable access device to the vehicle; and
an access module configured to
Generating a differential signal based on the received signal,
upsampling the differentiated signal to generate a first upsampled signal,
the desired signal is obtained or generated in a manner such that,
upsampling the desired signal to generate a second upsampled signal,
cross-correlating the first up-sampled signal and the second up-sampled signal to generate a cross-correlated signal,
determining a phase difference between the first up-sampled signal and the second up-sampled signal based on the cross-correlation signal,
Determining a round trip time of the signal received by the receiver, an
Granting access to the vehicle based on the round trip time.
2. The access system of claim 1, wherein the access module is configured to:
down-converting the signal to generate a down-converted signal;
sampling the down-converted signal to generate a sampled signal;
performing an arc tangent on the sampled signal to generate an arc tangent signal; and
differentiating the arctan signal to generate the differentiated signal.
3. The access system of claim 1, wherein the access module is configured to:
determining at least one of a location or a distance of the portable access device relative to the vehicle based on the round trip time; and
granting access to the vehicle based on at least one of the location or the distance.
4. The access system of claim 1, wherein the access module comprises:
a first upsampler configured to upsample the differentiated signal to generate the first upsampled signal; and
a second upsampler configured to upsample the desired signal to generate the second upsampled signal,
Wherein an upsampling rate of the first upsampler is the same as a sampling rate of the second upsampler.
5. The access system of claim 1, wherein the access module comprises:
a sign module configured to determine a sign of the differentiated signal; and
a bit pattern module configured to generate the expected signal based on the sign of the differentiated signal.
6. The access system of claim 1, wherein:
the access module is configured to obtain the expected signal; and
the expected signal is a predetermined signal obtained by the access module prior to receiving the received signal.
7. The access system of claim 1, wherein:
the access module is configured to perform an iterative process comprising:
multiplying bits of the first up-sampled signal and the second up-sampled signal to generate a resultant product,
summing the resulting products to generate a product-sum value, and
shifting the second up-sampled signal relative to the first up-sampled signal;
the iterative process provides a plurality of product-sum values; and
the access module is configured to determine the phase difference based on values of the plurality of product-sums.
8. The access system of claim 7, wherein the access module is configured to reconstruct the signal transmitted from the portable access device to the vehicle based on a zero crossing of a portion of the cross-correlation signal associated with a maximum of the values of the plurality of product-sums.
9. The access system of claim 1, wherein the access module comprises:
an upsampler configured to upsample the differentiated signal to generate the first upsampled signal;
a sign module configured to determine a sign of the first up-sampled signal; and
a bit pattern module configured to generate the expected signal based on a symbol of the first up-sampled signal.
10. A portable access device for an access system of a vehicle, the portable access device comprising:
a receiver configured to receive a signal transmitted from an access module of a vehicle to the portable access device; and
a control module configured to:
generating a differential signal based on the received signal,
upsampling the differentiated signal to generate a first upsampled signal,
the desired signal is obtained or generated in a manner such that,
Upsampling the desired signal to generate a second upsampled signal,
cross-correlating the first up-sampled signal and the second up-sampled signal to generate a cross-correlated signal,
determining a phase difference between the first up-sampled signal and the second up-sampled signal based on the cross-correlation signal,
determining a round trip time of the signal received by the receiver, an
One of the following:
transmitting the round trip time to the vehicle to gain access to the vehicle based on the round trip time, or
Determining at least one of a location or a distance between the portable access device and the vehicle, and transmitting the at least one of the location or the distance to the vehicle to obtain access to the vehicle.
11. The portable access device of claim 10, wherein the control module is configured to:
down-converting the signal to generate a down-converted signal;
sampling the down-converted signal to generate a sampled signal;
performing an arc tangent on the sampled signal to generate an arc tangent signal; and
differentiating the arctan signal to generate the differentiated signal.
12. The portable access device of claim 10, wherein the control module is configured to:
determining at least one of a location or a distance of the portable access device relative to the vehicle based on the round trip time; and
transmitting at least one of the location or the distance to the vehicle to obtain access to the vehicle based on the at least one of the location or the distance.
13. The portable access device of claim 10, wherein the control module comprises:
a first upsampler configured to upsample the differentiated signal to generate the first upsampled signal; and
a second upsampler configured to upsample the desired signal to generate the second upsampled signal,
wherein an upsampling rate of the first upsampler is the same as a sampling rate of the second upsampler.
14. The portable access device of claim 10, wherein the control module comprises:
a sign module configured to determine a sign of the differentiated signal; and
a bit pattern module configured to generate the expected signal based on the sign of the differentiated signal.
15. The portable access device of claim 10, wherein:
the control module is configured to obtain the expected signal; and
the expected signal is a predetermined signal obtained by the control module before receiving the received signal.
16. The portable access device of claim 10, wherein:
the control module is configured to perform an iterative process comprising:
multiplying bits of the first up-sampled signal and the second up-sampled signal to generate a resultant product,
summing the resulting products to generate a product-sum value, an
Shifting the second up-sampled signal relative to the first up-sampled signal;
the iterative process provides a plurality of product-sum values; and
the control module is configured to determine the phase difference based on values of the plurality of product-sums.
17. The portable access device of claim 17, wherein the control module is configured to reconstruct the signal sent from the access module of the vehicle to the portable access device based on a zero crossing of a portion of the cross-correlation signal associated with a maximum of the values of the plurality of product-sums.
18. The portable access device of claim 10, wherein the control module comprises:
an upsampler configured to upsample the differentiated signal to generate the first upsampled signal;
a sign module configured to determine a sign of the first up-sampled signal; and
a bit pattern module configured to generate the expected signal based on the symbols of the first up-sampled signal.
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Application Number | Priority Date | Filing Date | Title |
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US201962823210P | 2019-03-25 | 2019-03-25 | |
US62/823,210 | 2019-03-25 | ||
US201962826212P | 2019-03-29 | 2019-03-29 | |
US201962826239P | 2019-03-29 | 2019-03-29 | |
US62/826,239 | 2019-03-29 | ||
US62/826,212 | 2019-03-29 | ||
US16/598,191 US10991182B2 (en) | 2018-10-12 | 2019-10-10 | Multi-axis polarized RF antenna assemblies for passive entry/passive start systems |
US16/598,191 | 2019-10-10 | ||
US16/824,280 | 2020-03-19 | ||
US16/824,280 US11428799B2 (en) | 2018-10-12 | 2020-03-19 | Up-sampling and cross-correlation for time of arrival determinations in passive entry/passive start systems |
PCT/US2020/024672 WO2020198335A1 (en) | 2019-03-25 | 2020-03-25 | Up-sampling and cross-correlation for time of arrival determinations in passive entry/passive start systems |
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CN102087299A (en) * | 2009-12-03 | 2011-06-08 | 索尼公司 | Velocity calculating apparatus, velocity calculating method, navigation apparatus, and mobile phone with navigation function |
US20180138993A1 (en) * | 2016-11-11 | 2018-05-17 | Nxp B.V. | Processing module and associated method |
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