JP2014138345A - Communication system and communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make implementation of relay attack difficult.SOLUTION: Upon receiving an authentication request signal transmitted from an on-vehicle communication device, a portable device transmits a response signal to the on-vehicle communication device. The transmission control unit of the portable device changes the maximum frequency shift in the way, when transmitting the response signal while performing FSK modulation. In response thereto, the reception unit of the on-vehicle communication device changes the maximum frequency shift in the way, when receiving and demodulating the response signal. The invention is applicable to a communication system for vehicle, for example.

Description

  The present invention relates to a communication system and a communication apparatus, and more particularly, to a communication system and a communication apparatus that make it difficult to implement a relay attack.

  In recent years, by performing wireless communication between an in-vehicle communication device provided in a vehicle and a portable device possessed by a user, the vehicle can be used without using a mechanical key or operating the portable device. An electronic key system having a function that enables unlocking and locking of a door (hereinafter referred to as an automatic entry function) is becoming widespread.

  The automatic entry function is roughly divided into the following two types. First, when a user carrying a portable device performs a predetermined operation (for example, touching a door, operating a button provided on the door) on the vehicle, the door of the vehicle automatically It is a method of unlocking or locking. In this method, for example, when a user performs a predetermined operation on the vehicle, an authentication request signal is transmitted from the in-vehicle communication device to a predetermined area, and the portable device that has received the authentication request signal includes a response including authentication information. When the signal is transmitted and the authentication is successful, the door is unlocked or locked.

  The second is a method in which the door is automatically unlocked when the user carrying the portable device approaches the vehicle, and the door is automatically locked when the user moves away from the vehicle. In this method, for example, when an authentication request signal is periodically transmitted from a vehicle-mounted communication device to a predetermined area, a portable device that has received the authentication request signal transmits a response signal including authentication information, and when authentication is successful, When the door is unlocked and the response signal cannot be received, the door is locked.

  By the way, a vehicle having an automatic entry function has a risk of being stolen or invaded by using a method called a relay attack. Here, the relay attack means that a malicious third party uses a repeater to connect the in-vehicle communication device and the portable device even though the user who owns the portable device is outside the communication area of the in-vehicle communication device. This is a technique for performing an illegal act such as unlocking a door of a vehicle.

  Therefore, conventionally, as a countermeasure against relay attack, for example, it has been proposed to transmit a request signal twice from an in-vehicle communication device to a portable device (see, for example, Patent Document 1). In Patent Document 1, the portable device notifies the reply mode for the second request signal when responding to the first request signal, and responds to the second request signal in the notified reply mode. As a result, although the required time until the authentication is completed becomes longer by transmitting the request signal twice, it is difficult for the repeater to grasp and switch the reply mode, so that it is difficult to perform the relay attack. .

  In addition to countermeasures against relay attacks, the same signal from the portable device is FSK modulated with different maximum frequency shifts and transmitted multiple times, thereby causing disturbance to the wireless communication between the portable device and the in-vehicle communication device, etc. It has been proposed to prevent interference due to (see, for example, Patent Document 2).

JP 2011-52412 A JP 2012-209924 A

  The present invention makes it difficult to implement a relay attack.

  The communication system according to the first aspect of the present invention is a communication system in which a first communication device and a second communication device perform wireless communication. The first communication device performs FSK modulation on a signal to the second communication device. A first transmission unit that transmits the first transmission unit and a first transmission control unit that controls the first transmission unit, and the second communication device receives and demodulates a signal from the first communication device. The first transmission control unit controls the maximum frequency deviation to be changed in the middle when the predetermined first signal is FSK modulated and transmitted, and the first reception unit When the first signal is received and demodulated, the maximum frequency deviation is changed in accordance with the change of the maximum frequency deviation during the FSK modulation of the first signal.

  In the first aspect of the present invention, when the predetermined first signal is FSK modulated and transmitted in the first communication device, the maximum frequency shift is changed in the middle, and the second communication device performs the first operation. When the first signal is received and demodulated, the maximum frequency deviation is changed in accordance with the change of the maximum frequency deviation during the FSK modulation of the first signal.

  Therefore, it is possible to make it difficult to perform a relay attack.

  For example, one of the first communication device and the second communication device includes a vehicle key fob, and the other includes a vehicle-mounted communication device. The first transmission unit includes, for example, various transmission circuits or a dedicated IC. The first transmission control unit is configured by a microcomputer including a processor such as a CPU, or an ECU. The first receiving unit includes, for example, various receiving circuits or a dedicated IC.

  The first communication device further includes a second receiving unit that receives and demodulates a signal from the second communication device, the second communication device is provided in the vehicle, and the second communication device includes A second transmission unit that modulates and transmits a signal to the first communication device, a second transmission control unit that controls the second transmission unit, and a vehicle control unit that controls processing of the vehicle The second transmission control unit is controlled to transmit a predetermined second signal when a predetermined operation is performed on the vehicle or periodically, and the first transmission control is performed. The vehicle control unit controls the vehicle to transmit a first signal as a response signal to the second signal, and when the vehicle control unit receives a regular first signal from the first communication device, The execution of the process can be commanded.

  Accordingly, for example, it is possible to make it difficult to perform a relay attack in a vehicle having an automatic entry function.

  The second receiving unit is configured by various receiving circuits or a dedicated IC, for example. The second transmission unit includes, for example, various transmission circuits or a dedicated IC. This 2nd transmission control part is comprised by the microcomputer provided with processors, such as CPU, ECU, etc., for example. This vehicle control part is comprised by microcomputer provided with processors, such as CPU, ECU, etc., for example.

  The first communication device is provided in a vehicle, and the first communication device includes a second receiving unit that receives and demodulates a signal from the second communication device, and a vehicle control unit that controls processing of the vehicle. The second communication device includes a second transmission unit that modulates and transmits a signal to the first communication device, and a second transmission control unit that controls the second transmission unit. Further, the first transmission control unit is configured to control the first signal to be transmitted when a predetermined operation is performed on the vehicle or periodically, and the second transmission control unit. Is configured to transmit a second signal as a response signal to the first signal, and when the vehicle control unit receives a regular second signal from the second communication device, the vehicle control unit Execution of processing can be commanded.

  Accordingly, for example, it is possible to make it difficult to perform a relay attack in a vehicle having an automatic entry function.

  The second receiving unit is configured by various receiving circuits or a dedicated IC, for example. This vehicle control part is comprised by microcomputer provided with processors, such as CPU, ECU, etc., for example. The second transmission unit includes, for example, various transmission circuits or a dedicated IC. This 2nd transmission control part is comprised by the microcomputer provided with processors, such as CPU, ECU, etc., for example.

  The first transmission control unit can be controlled to transmit the first signal divided into at least a first divided signal and a second divided signal.

  The first transmission control unit performs FSK modulation on the first divided signal with a predetermined first maximum frequency shift, and with a predetermined second maximum frequency shift different from the first maximum frequency shift. The first divided signal is demodulated with the first maximum frequency shift, and the second maximum frequency shift with the second maximum frequency shift. The divided signal can be demodulated.

  Thereby, the switching of the maximum frequency deviation between the transmission side and the reception side can be reliably synchronized.

  In the first transmission control unit, a change position of the maximum frequency shift when the second divided signal is FSK-modulated is set, and the set change position is notified to the second communication device by the first divided signal. At the same time, the maximum frequency shift at the time of FSK modulation of the second divided signal is controlled to be changed at the change position, and the first receiving unit has the change position notified by the first divided signal at the change position. The second frequency can be demodulated by changing the maximum frequency shift.

  Thereby, implementation of a relay attack can be made more difficult.

  In this first transmission control unit, a second maximum frequency deviation different from the predetermined first maximum frequency deviation is set, and the set second maximum frequency deviation is set to the second by the first divided signal. The first divided signal is FSK modulated with the first maximum frequency deviation, and the second divided signal is FSK modulated with the second maximum frequency deviation. The first receiving unit demodulates the first divided signal with the first maximum frequency deviation and demodulates the second divided signal with the second maximum frequency deviation notified by the first divided signal. Can do.

  Thereby, implementation of a relay attack can be made more difficult.

  The first transmission control unit controls the first signal to change the maximum frequency deviation at a predetermined position set in advance when the first signal is FSK-modulated. The unit can change the maximum frequency deviation at a predetermined position of the first signal when demodulating the first signal.

  Thereby, implementation of a relay attack can be made difficult.

  The first communication device further includes a second receiving unit that receives and demodulates a signal from the second communication device, the second communication device is provided in the vehicle, and the second communication device includes A second transmission unit that modulates and transmits a signal to the first communication device, a second transmission control unit that controls the second transmission unit, and a vehicle control unit that controls processing of the vehicle The second transmission control unit is controlled to transmit a predetermined second signal when a predetermined operation is performed on the vehicle or periodically, and the first transmission control is performed. The control unit causes the first signal to be divided into at least the first divided signal and the second divided signal and transmitted as a response signal to the second signal. When receiving the legitimate first divided signal from the communication device, the vehicle is instructed to execute the predetermined first process. , When receiving the second divided signal of the normal from the first communication device, it is possible to command the execution of the second process of a given vehicle.

  Accordingly, for example, it is possible to make it difficult to perform a relay attack in a vehicle having an automatic entry function. Moreover, the process which a vehicle performs can be switched with the position of a 1st communication apparatus.

  The second receiving unit is configured by various receiving circuits or a dedicated IC, for example. This 2nd transmission control part is comprised by the microcomputer provided with processors, such as CPU, ECU, etc., for example. The second transmission unit includes, for example, various transmission circuits or a dedicated IC. This vehicle control part is comprised by microcomputer provided with processors, such as CPU, ECU, etc., for example.

  A communication device according to a second aspect of the present invention is a communication device that performs wireless communication with another communication device, and transmits a signal to the other communication device by FSK modulation and a transmission for controlling the transmission unit. And a transmission control unit that controls the maximum frequency deviation to be changed in the middle when the predetermined signal is FSK modulated and transmitted.

  In the second aspect of the present invention, when a predetermined signal is FSK modulated and transmitted, the maximum frequency deviation is changed in the middle.

  Therefore, it is possible to make it difficult to perform a relay attack.

  For example, one of the communication device and the other communication device includes a vehicle key fob, and the other includes a vehicle-mounted communication device. For example, the transmission unit includes various transmission circuits or a dedicated IC. The transmission control unit is configured by, for example, a microcomputer provided with a processor such as a CPU, or an ECU.

  A communication device according to a third aspect of the present invention is a communication device that performs wireless communication with another communication device, and includes a reception unit that receives and demodulates an FSK-modulated signal from the other communication device. When receiving and demodulating a predetermined signal from another communication device, the maximum frequency shift is changed in the middle when the predetermined signal is FSK modulated in the other communication device. Change the frequency deviation.

  In the third aspect of the present invention, when the predetermined signal is received and demodulated, the maximum frequency deviation is changed in accordance with the change in the maximum frequency when the predetermined signal is FSK modulated. Is changed.

  Therefore, it is possible to make it difficult to perform a relay attack.

  For example, one of the communication device and the other communication device includes a vehicle key fob, and the other includes a vehicle-mounted communication device. For example, the receiving unit includes various receiving circuits or a dedicated IC.

  According to the first to third aspects of the present invention, it is possible to make it difficult to perform a relay attack.

It is a block diagram which shows one Embodiment of the communication system to which this invention is applied. It is a figure for demonstrating transmission mode and reception mode. It is a figure for demonstrating 1st Embodiment of the process of a communication system. It is a timing chart which shows the flow of the signal in 1st Embodiment of the process of a communication system. It is a timing chart which shows the flow of the signal of the conventional communication system. It is a figure for demonstrating 2nd Embodiment of the process of a communication system. It is a timing chart which shows the flow of the signal in 2nd Embodiment of the process of a communication system. It is a figure for demonstrating 3rd Embodiment of the process of a communication system. It is a timing chart which shows the flow of the signal in 3rd Embodiment of the process of a communication system. It is a figure for demonstrating 4th Embodiment of the process of a communication system. It is a timing chart which shows the flow of the signal in 4th Embodiment of the process of a communication system. It is a figure for demonstrating 5th Embodiment of the process of a communication system. It is a timing chart which shows the flow of the signal in 5th Embodiment of the process of a communication system.

Hereinafter, modes for carrying out the present invention (hereinafter referred to as embodiments) will be described. The description will be given in the following order.
1. Embodiment 2. FIG. Modified example

<1. Embodiment>
[Configuration Example of Communication System 101]
FIG. 1 shows an embodiment of a communication system 101 to which the present invention is applied. The communication system 101 is used to realize a predetermined function of the vehicle 102. Here, the predetermined function is, for example, unlocking and locking the door of the vehicle 102 without using a mechanical key or operating the portable device 112 (automatic entry function). It is possible to start a driving engine such as an engine or a motor by simply operating a button or the like of the vehicle 102 (hereinafter referred to as a push start function), or to light a welcome lamp (hereinafter referred to as a welcome lamp lighting function). Functions. The welcome lamp is a lamp that is provided in the vehicle, near the door mirror, and the like, and is lit for the purpose of confirming the vehicle 102 and surrounding conditions when the surroundings are dark.

  Further, as will be described later, the communication system 101 is provided with a measure for preventing a relay attack using the repeater 103.

  The communication system 101 is configured to include an in-vehicle communication device 111 provided in the vehicle 102 and a portable device 112 possessed by the user. The in-vehicle communication device 111 and the portable device 112 perform bidirectional wireless communication.

  The in-vehicle communication device 111 is configured to include an antenna 121, a reception unit 122, a control unit 123, a transmission unit 124, and an antenna 125.

  The receiving unit 122 is configured by various receiving circuits or a dedicated IC, for example. The receiving unit 122 receives an FSK-modulated UHF band signal (hereinafter referred to as an RF signal) from the portable device 112 via the antenna 121 under the control of the reception control unit 131 of the control unit 123 and receives the received signal. The received RF signal is demodulated. The receiving unit 122 can change the reception mode when receiving and demodulating the RF signal, and the reception mode is set under the control of the reception control unit 131. Further, the reception unit 122 supplies a baseband signal obtained by demodulating the RF signal to the reception control unit 131.

  Details of the reception mode will be described later.

  The control unit 123 is configured by, for example, a microcomputer including a processor such as a CPU (Central Processing Unit) or an ECU (Electronic Control Unit). The control unit 123 is configured to include a reception control unit 131, a signal processing unit 132, a transmission control unit 133, and a vehicle control unit 134.

  The reception control unit 131 controls the reception unit 122. Further, the reception control unit 131 supplies the baseband signal supplied from the reception unit 122 to the signal processing unit 132.

  The signal processing unit 132 performs various types of signal processing (for example, signal analysis and processing based on the analysis result) on the baseband signal supplied from the reception control unit 131. In addition, the signal processing unit 132 notifies the reception control unit 131, the transmission control unit 133, and the vehicle control unit 134 of the result of signal processing as necessary. Furthermore, the signal processing unit 132 generates a signal (baseband signal) to be transmitted to the portable device 112 based on the signal processing result, a command from the vehicle control unit 134, and the like, and supplies the signal to the transmission control unit 133.

  The transmission control unit 133 supplies the baseband signal supplied from the signal processing unit 132 to the transmission unit 124. Further, the transmission control unit 133 controls the transmission unit 124.

  The vehicle control unit 134 communicates with other devices (such as an ECU) provided in the vehicle 102 to transmit and receive various types of information, give commands, and receive commands.

  The transmission unit 124 includes, for example, various transmission circuits or a dedicated IC. Under the control of the transmission control unit 133, the transmission unit 124 ASK modulates the baseband signal supplied from the transmission control unit 133 with a carrier wave in the LF band. In addition, the transmission unit 124 transmits a modulated signal (hereinafter referred to as an LF signal) to the portable device 112 via the antenna 125 under the control of the transmission control unit 133.

  The portable device 112 is configured by, for example, a key fob possessed by a user who uses the vehicle 102. The portable device 112 is configured to include an antenna 141, a reception unit 142, an operation unit 143, a control unit 144, a transmission unit 145, and an antenna 146.

  The receiving unit 142 includes, for example, various receiving circuits or a dedicated IC. The receiving unit 142 receives an LF signal from the in-vehicle communication device 111 via the antenna 141 under the control of the reception control unit 151 of the control unit 144, and demodulates the received LF signal. In addition, the reception unit 122 supplies a baseband signal obtained by demodulating the LF signal to the reception control unit 151.

  The operation unit 143 includes, for example, buttons and switches, and is operated when a predetermined operation of the vehicle 102 is performed. The operation unit 143 supplies a signal indicating the operation content to the signal processing unit 152 of the control unit 144.

  The control unit 144 is configured by, for example, a microcomputer having a processor such as a CPU. The control unit 144 is configured to include a reception control unit 151, a signal processing unit 152, and a transmission control unit 153.

  The reception control unit 151 controls the reception unit 142. Further, the reception control unit 151 supplies the baseband signal supplied from the reception unit 142 to the signal processing unit 152.

  The signal processing unit 152 performs various types of signal processing (for example, signal analysis and processing based on the analysis result) on the baseband signal supplied from the reception control unit 151. Further, the signal processing unit 152 notifies the reception control unit 151 and the transmission control unit 153 of the result of signal processing as necessary. Further, the signal processing unit 152 generates a signal (baseband signal) to be transmitted to the in-vehicle communication device 111 based on the signal processing result, the operation signal from the operation unit 143, and the like, and supplies the signal to the transmission control unit 153. .

  The transmission control unit 153 supplies the baseband signal supplied from the signal processing unit 152 to the transmission unit 124. The transmission control unit 153 controls the transmission unit 145.

  The transmission unit 145 includes, for example, various transmission circuits or a dedicated IC. The transmission unit 145 performs FSK modulation of the baseband signal supplied from the transmission control unit 153 with a UHF carrier wave under the control of the transmission control unit 153. Further, the transmission unit 145 can change the transmission mode when the baseband signal is modulated and transmitted, and the transmission mode is set under the control of the transmission control unit 153. In each transmission mode, as described later, the value of the maximum frequency deviation in FSK modulation is different. Further, the transmission unit 145 transmits the modulated RF signal to the in-vehicle communication device 111 via the antenna 146 under the control of the transmission control unit 153.

[Transmission mode and reception mode]
Here, with reference to FIG. 2, the transmission mode of the transmission part 145 of the portable device 112 and the reception mode of the reception part 122 of the vehicle-mounted communication apparatus 111 are demonstrated.

  For example, the transmission mode of the transmission unit 145 includes two transmission modes, a narrowband transmission mode and a wideband transmission mode. The upper graph in FIG. 2 shows the frequency spectrum of the RF signal transmitted from the transmission unit 145 in the narrowband transmission mode, and the lower graph shows the frequency spectrum of the RF signal transmitted from the transmission unit 145 in the wideband transmission mode. Is shown.

  In the narrowband transmission mode, the center frequency during FSK modulation is set to f0, and the maximum frequency deviation is set to Δfa. Accordingly, of the two carriers used for FSK modulation, the peak frequency f1a of the low frequency carrier is f0−Δfa / 2, and the peak frequency f2a of the high frequency carrier is f0 + Δfa / 2.

  On the other hand, in the wideband transmission mode, the center frequency at the time of FSK modulation is set to the same f0 as in the narrowband transmission mode, and the maximum frequency deviation is set to Δfb wider than that in the narrowband transmission mode. Accordingly, of the two carriers used for FSK modulation, the peak frequency f1b of the low frequency carrier is f0−Δfb / 2, and the peak frequency f2b of the high frequency carrier is f0 + Δfb / 2. The peak frequency f1b is lower than the peak frequency f1a in the narrowband transmission mode, and the peak frequency f2b is higher than the peak frequency f2a in the narrowband transmission mode.

  In this way, by changing the transmission mode, the width (band) of the maximum frequency deviation is changed while the center frequency at the time of FSK modulation is fixed to f0. Along with this, the peak frequency of the carrier on the low frequency side and the peak frequency of the carrier on the high frequency side change around the center frequency f0.

  In general, the smaller the maximum frequency deviation of the FSK modulation, the better the communication performance and the longer the communicable distance, and the larger the maximum frequency deviation, the worse the communication performance and the communicable distance. Shorter.

  On the other hand, the reception mode of the reception unit 122 corresponds to the transmission mode of the transmission unit 145, and includes, for example, a narrowband reception mode corresponding to the narrowband transmission mode and a wideband reception mode corresponding to the wideband transmission mode. .

  In the narrowband reception mode, as in the narrowband transmission mode, the center frequency at the time of demodulation is set to f0, and the maximum frequency deviation is set to Δfa. As a result, for example, the peak frequency of the low-frequency carrier among the two carriers used for demodulation is set to f1a so that the value before modulation of the FSK-modulated RF signal can be accurately detected. The peak frequency of the carrier wave is set to f2a.

  On the other hand, in the wideband reception mode, as in the wideband transmission mode, the center frequency at the time of demodulation is set to f0, and the maximum frequency deviation is set to Δfb. As a result, for example, the peak frequency of the low-frequency carrier among the two carriers used for demodulation is set to f1b so that the value before modulation of the FSK-modulated RF signal can be accurately detected. The peak frequency of the carrier wave is set to f2b.

  As described above, by changing the reception mode, the width (band) of the maximum frequency shift is changed while the center frequency at the time of demodulation is fixed to f0. Along with this, for example, the peak frequency of the low-frequency carrier used for demodulation to the digital signal and the peak frequency of the high-frequency carrier change around the center frequency f0.

  In this example, two types of transmission modes, the narrowband transmission mode and the wideband transmission mode, are provided. However, by increasing the types of maximum frequency deviation values, it is possible to provide three or more types of transmission modes. Is possible. Similarly, it is possible to provide three or more types of reception modes by increasing the types of maximum frequency deviation values.

  Hereinafter, the maximum frequency shift in the narrowband transmission mode and the narrowband reception mode is also referred to as a narrowband maximum frequency shift, and the maximum frequency shift in the wideband transmission mode and the wideband reception mode is also referred to as a wideband maximum frequency shift. .

[First Embodiment of Processing of Communication System 101]
Next, the first embodiment of the processing of the communication system 101 will be described with reference to FIGS.

  3 is a flowchart for explaining the first embodiment of the processing of the communication system 101, and FIG. 4 is a timing chart showing the signal flow of the communication system 101. As shown in FIG.

  In step S1, the reception control unit 131 of the in-vehicle communication device 111 sets the reception unit 122 to the narrow band reception mode.

  In step S2, the in-vehicle communication device 111 transmits an authentication request signal. Specifically, the signal processing unit 132 generates an authentication request signal and supplies it to the transmission unit 124 via the transmission control unit 133. Transmitter 124 performs ASK modulation on the authentication request signal, and transmits the modulated authentication request signal via antenna 125.

  As a result of this processing, an authentication request signal is transmitted from the in-vehicle communication device 111 to the portable device 112 as shown in the top part of the timing chart of FIG.

  It should be noted that the authentication request signal is transmitted to the vehicle 102 when a predetermined operation (for example, touching the door of the vehicle 102 or operating a button or the like provided on the door) is performed. Alternatively, it may be transmitted periodically. Hereinafter, the former method is referred to as a post-authentication method, and the latter method is referred to as a pre-authentication method. In the following, a description will be given mainly of processing when the post-authentication method is mainly employed.

  In step S3, the signal processing unit 152 of the portable device 112 determines whether an authentication request signal has been received. The determination process in step S3 is repeatedly executed until it is determined that the authentication request signal has been received.

  And the receiving part 142 of the portable device 112 demodulates the received authentication request signal, when the authentication request signal transmitted from the vehicle-mounted communication apparatus 111 by the process of step S1 is received via the antenna 141. In addition, the reception unit 142 supplies the demodulated authentication request signal to the signal processing unit 152 via the reception control unit 151. Here, the signal processing unit 152 determines that the authentication request signal has been received, and the process proceeds to step S4.

  In step S4, the portable device 112 transmits a predetermined portion of the data included in the response signal in the narrowband transmission mode. Specifically, the signal processing unit 152 generates a response signal for the authentication request signal received from the in-vehicle communication device 111 and supplies the response signal to the transmission unit 145 via the transmission control unit 153.

  For example, as shown in FIG. 4, the response signal includes blocks of a synchronization code part, a command part, a data part, and a CW (Continuous Wave) part.

  The synchronization code unit is a block including a synchronization code having a predetermined value for synchronizing the portable device 112 and the in-vehicle communication device 111.

  The command part is a block including a command for instructing a process executed by the vehicle 102.

  The data part is a block including data necessary for the vehicle 102 to execute the processing instructed by the command. The data part includes at least authentication information such as an ID for identifying the portable device 112.

  The CW unit is a block including a continuous wave for measuring the radio field intensity of the response signal.

  In the example of FIG. 4, it is determined in advance that the synchronization code part of the response signal is transmitted in the narrowband transmission mode and the other part is transmitted in the wideband transmission mode. Then, the transmission unit 145 performs FSK modulation on the synchronization code unit with a narrowband maximum frequency shift, and transmits the result via the antenna 146.

  Hereinafter, an example in which the transmission mode is changed in the command section as shown in FIG. 4 will be described.

  In step S5, the signal processing unit 132 of the in-vehicle communication device 111 determines whether or not a predetermined part of the response signal transmitted in the narrowband transmission mode has been received. Specifically, when the reception unit 122 of the in-vehicle communication device 111 receives the synchronization code portion of the response signal transmitted from the portable device 112 in the process of step S4 via the antenna 121, the reception synchronization code portion is received. Demodulate with narrowband maximum frequency shift. In addition, the reception unit 122 supplies the synchronization code portion of the demodulated response signal to the signal processing unit 132 via the reception control unit 131. Furthermore, the receiving unit 122 performs phase synchronization based on the synchronization code included in the synchronization code unit. When the above processing is performed within a predetermined time after transmitting the authentication request signal, the signal processing unit 132 determines that the portion of the response signal before the change of the transmission mode has been received, and the processing is step S6. Proceed to

  In step S6, the reception control unit 131 of the in-vehicle communication device 111 changes the reception unit 122 to the wideband reception mode.

  In step S7, the portable device 112 transmits the remaining part of the response signal in the wideband transmission mode. Specifically, under the control of the transmission control unit 153, the transmission unit 145 performs FSK modulation on the response signal command unit to CW unit with a wideband maximum frequency shift, as shown in FIG. To send through. As a result, the maximum frequency shift of the FSK modulation is switched in the middle of the response signal.

  Thereafter, the process of the portable device 112 returns to step S3, and the processes after step S3 are executed.

  In step S8, the signal processing unit 132 of the in-vehicle communication device 111 determines whether a normal response signal has been received. Specifically, when the receiving unit 122 of the in-vehicle communication device 111 receives the command unit through the CW unit of the response signal transmitted from the portable device 112 in the process of step S7 via the antenna 121, the received unit The part is demodulated with a wideband maximum frequency shift. In addition, the reception unit 122 supplies the command unit to the CW unit of the demodulated response signal to the signal processing unit 132 via the reception control unit 131. The signal processing unit 132 collates authentication information of the portable device 112 included in the data unit. Then, when the authentication information is regular authentication information, the signal processing unit 132 determines that a regular response signal has been received, and the process proceeds to step S9.

  In step S <b> 9, the vehicle control unit 134 of the in-vehicle communication device 111 commands execution of predetermined processing of the vehicle 102. Specifically, the signal processing unit 132 supplies a command included in the command part of the response signal to the vehicle control unit 134. The vehicle control unit 134 instructs another device of the vehicle 102 such as an ECU to execute processing corresponding to the acquired command. Thereby, for example, the automatic entry function, push start function, welcome lamp lighting function and the like described above are executed.

  Thereafter, the processing of the in-vehicle communication device 111 ends.

  On the other hand, in step S8, if the signal processing unit 132 fails to receive any or all of the command part, the data part, and the CW part of the response signal, or if the authentication of the response signal fails, the normal response signal Is not received, and the processing of the in-vehicle communication device 111 ends.

  In step S5, if the signal processing unit 132 fails to receive the response code synchronization code unit, the remaining part of the response signal transmission mode is not modulated, and the processing of the in-vehicle communication device 111 ends.

  In the case of the pre-authentication method, for example, when it is determined in step S5 that the part before the change of the transmission mode of the response signal has not been received, it is determined in step S8 that the regular response signal has not been received. In the case, or when the process of step S9 is completed, the process of the in-vehicle communication device 111 returns to step S1, and the processes after step S1 are executed.

  As described above, conventionally, as shown in FIG. 5, the maximum frequency shift of the response signal during FSK modulation is fixed to the same band, whereas in the communication system 101, as shown in FIG. In addition, the maximum frequency deviation is changed in the middle of the response signal. More precisely, during transmission of the response signal, the bandwidth of the maximum frequency shift is widened while the center frequency between the two carriers remains fixed. Further, the maximum frequency deviation at the time of demodulation is changed in accordance with the change of the maximum frequency deviation at the time of FSK modulation of the response signal.

  On the other hand, it is difficult for the repeater 103 to detect and follow the change in the maximum frequency shift of the FSK modulation when the response signal is relayed. Therefore, there is a high possibility that the repeater 103 will fail to relay the response signal, and as a result, it becomes difficult to perform the relay attack.

  In addition, ICs that can easily change the maximum frequency deviation are commercially available. By adopting such an IC, an in-vehicle communication device can be easily obtained without complicating the circuit configuration or increasing the circuit scale. 111 and the portable device 112 can be realized.

  Furthermore, since it is not necessary to add a new signal to be transmitted / received or to add new information to each signal, the processing time is almost the same as in the prior art.

[Second Embodiment of Processing of Communication System 101]
Next, a second embodiment of the processing of the communication system 101 will be described with reference to FIGS. In the second embodiment, the response signal is divided into two signals, that is, an authentication signal (first divided signal) and a command signal (second divided signal), and is transmitted from the portable device 112.

  6 is a flowchart for explaining the second embodiment of the processing of the communication system 101, and FIG. 7 is a timing chart showing the signal flow of the communication system 101.

  In step S51, the receiving unit 122 of the in-vehicle communication device 111 is set to the narrowband reception mode, similarly to the process in step S1 of FIG.

  In step S52, an authentication request signal is transmitted from the in-vehicle communication device 111 in the same manner as in step S2 of FIG.

  In step S53, similarly to the process of step S3 in FIG. 3, it is determined whether or not the portable device 112 has received the authentication request signal. If it is determined that the authentication request signal has been received, the process proceeds to step S54. move on.

  In step S54, the portable device 112 transmits an authentication signal in the narrow band mode. Specifically, the signal processing unit 152 generates an authentication signal for the authentication request signal received from the in-vehicle communication device 111 and supplies the authentication signal to the transmission unit 145 via the transmission control unit 153.

  For example, as shown in FIG. 7, the authentication signal is composed of blocks of a synchronization code part and an authentication data part.

  The synchronization code part is the same block as the synchronization code part of the response signal in FIG.

  The authentication data part is a block including authentication information of the portable device 112.

  Then, under the control of the transmission control unit 153, the transmission unit 145 performs FSK modulation on the authentication signal with a narrowband maximum frequency shift and transmits the authentication signal via the antenna 146.

  In step S55, the signal processing unit 132 of the in-vehicle communication device 111 determines whether or not a regular authentication signal has been received. Specifically, when the reception unit 122 of the in-vehicle communication device 111 receives the authentication signal transmitted from the portable device 112 in the process of step S54 via the antenna 121, the received authentication signal is transmitted to the narrowband maximum frequency. Demodulate with deviation. In addition, the reception unit 122 supplies the demodulated authentication signal to the signal processing unit 132 via the reception control unit 131. Furthermore, the receiving unit 122 performs phase synchronization based on the synchronization code included in the synchronization code portion of the authentication signal. In addition, the signal processing unit 132 collates the authentication information of the portable device 112 included in the authentication data unit, and determines that the normal authentication signal has been received when the authentication information is normal authentication information. Proceed to step S56.

  In step S56, the reception unit 122 of the in-vehicle communication device 111 is changed to the wideband reception mode, similarly to the processing in step S6 of FIG.

  In step S <b> 57, the vehicle control unit 134 of the in-vehicle communication device 111 commands the execution of the first process of the vehicle 102. Specifically, the signal processing unit 132 notifies the vehicle control unit 134 that a regular authentication signal has been received. The vehicle control unit 134 instructs other devices of the vehicle 102 such as an ECU to execute a predetermined first process.

  Here, for example, a process (for example, a welcome lamp lighting function or the like) that is not directly related to entry / exit to the vehicle 102 or driving and has a low possibility of the vehicle 102 being stolen or invaded even if executed is performed in the first process. It is executed as a process.

  In step S58, the portable device 112 transmits the command signal in the wideband transmission mode. Specifically, the signal processing unit 152 generates a command signal for the authentication request signal received from the in-vehicle communication device 111 and supplies the command signal to the transmission unit 145 via the transmission control unit 153.

  For example, as shown in FIG. 7, the command signal includes blocks of a synchronization code part, a command part, a data part, and a CW part. The command signal has the same configuration as that of the response signal in FIG. 4, but a part of the data previously transmitted by the authentication signal can be omitted as compared with the response signal in FIG. 4.

  Then, under the control of the transmission control unit 153, the transmission unit 145 performs FSK modulation of the command signal with a wideband maximum frequency shift and transmits the command signal via the antenna 146. A predetermined interval is provided between the end of transmission of the authentication signal and the start of transmission of the command signal.

  As a result, as shown in FIG. 7, the maximum frequency shift of the FSK modulation is switched in the middle of the response signal, more strictly, between the authentication signal and the command signal constituting the response signal.

  Thereafter, the process of the portable device 112 returns to step S53, and the processes after step S53 are executed.

  In step S59, the signal processing unit 132 of the in-vehicle communication device 111 determines whether or not a normal response signal has been received. Specifically, when the reception unit 122 of the in-vehicle communication device 111 receives the command signal transmitted from the portable device 112 through the antenna 121 in the process of step S58, the received command signal is converted to the wideband maximum frequency shift. Demodulate with. The receiving unit 122 also supplies the demodulated command signal to the signal processing unit 132 via the reception control unit 131. The signal processing unit 132 collates the authentication information of the portable device 112 included in the data part of the command signal. Then, if the authentication information is regular authentication information, the signal processing unit 132 determines that a regular command signal has been received, and further includes a regular response signal (that is, a combination of a regular authentication signal and a regular command signal). ) And the process proceeds to step S60.

  In step S <b> 60, the vehicle control unit 134 of the in-vehicle communication device 111 instructs the execution of the second process of the vehicle 102. Specifically, the signal processing unit 132 supplies a command included in the command part of the command signal to the vehicle control unit 134. The vehicle control unit 134 instructs other devices of the vehicle 102 such as an ECU (Engine Control Unit) to execute the second process corresponding to the acquired command.

  Here, for example, a process (for example, an automatic entry function, a push start function, etc.) directly related to entry / exit to the vehicle 102 or driving is executed as the second process.

  Thereafter, the processing of the in-vehicle communication device 111 ends.

  On the other hand, in step S59, if the signal processing unit 132 fails to receive the command signal or fails to authenticate the command signal, the signal processing unit 132 determines that the legitimate response signal has not been received, and the processing of the in-vehicle communication device 111 is performed. Ends.

  In step S55, if the signal processing unit 132 fails to receive the authentication signal, or if the authentication signal authentication fails, the signal processing unit 132 determines that the regular authentication signal has not been received, and the processing of the in-vehicle communication device 111 is performed. Ends.

  In the case of the pre-authentication method, for example, when it is determined in step S55 that a normal authentication signal has not been received, in step S59, it is determined that a normal response signal has not been received, or in step S60. When the process is completed, the process of the in-vehicle communication device 111 returns to step S51, and the processes after step S51 are executed.

  As described above, in the second embodiment, the response signal is divided into the authentication signal and the command signal, and the transmission mode is switched between the response signal and the command signal. The switching of the reception mode of the device 111 can be reliably synchronized.

  Further, the processing of the vehicle 102 is executed in two stages, that is, when an authentication signal is received and when a command signal is received. As a result, for example, as described above, when the maximum frequency deviation is in the narrow band, the communicable distance is longer than in the case of the wide band. Accordingly, the functions that can be executed by the vehicle 102 can be switched.

[Third Embodiment of Processing of Communication System 101]
Next, a third embodiment of the processing of the communication system 101 will be described with reference to FIGS. In the third embodiment, a response signal is transmitted from the portable device 112 in two parts, an authentication signal and a command signal, and the change position of the command signal transmission mode is made variable.

  FIG. 8 is a flowchart for explaining the third embodiment of the processing of the communication system 101, and FIG. 9 is a timing chart showing the signal flow of the communication system 101.

  In step S101, the reception unit 122 of the in-vehicle communication device 111 is set to the narrowband reception mode, similarly to the process in step S1 of FIG.

  In step S102, an authentication request signal is transmitted from the in-vehicle communication device 111 in the same manner as in step S2 of FIG.

  In step S103, similarly to the process of step S3 in FIG. 3, it is determined whether or not the portable device 112 has received the authentication request signal. If it is determined that the authentication request signal has been received, the process proceeds to step S104. move on.

  In step S104, the signal processing unit 152 of the portable device 112 sets a command signal transmission mode change position. Specifically, the signal processing unit 152 sets which block of the synchronization code part to the CW part of the command signal is changed to the wideband transmission mode.

  Note that the change position of the transmission mode may be set, for example, randomly or according to a predetermined rule.

  In step S105, the portable device 112 transmits an authentication signal including the setting content in the narrowband transmission mode. Specifically, the signal processing unit 152 generates an authentication signal for the authentication request signal received from the in-vehicle communication device 111 and supplies the authentication signal to the transmission unit 145 via the transmission control unit 153.

  For example, as shown in FIG. 9, the authentication signal is composed of blocks of a synchronization code part and an authentication / setting data part.

  The synchronization code part is the same block as the synchronization code part of the response signal in FIG.

  The authentication / setting data part is a block including authentication information of the portable device 112 and setting information of a change position of the transmission mode of the command signal.

  Then, under the control of the transmission control unit 153, the transmission unit 145 performs FSK modulation on the authentication signal with a narrowband maximum frequency shift and transmits the authentication signal via the antenna 146. Thereby, the change position of the transmission mode of the command signal is notified to the in-vehicle communication device 111 using the authentication signal.

  In step S106, as in the process of step S55 of FIG. 6, it is determined in the in-vehicle communication device 111 whether or not a regular authentication signal has been received. If it is determined that a regular authentication signal has been received, the process proceeds to step S107.

  In step S107, the in-vehicle communication device 111 sets the change position of the command signal reception mode. Specifically, the signal processing unit 132 notifies the reception control unit 131 of the change position of the transmission mode of the command signal indicated in the authentication / setting data unit of the authentication signal. The reception control unit 131 stores the notified change position as a position for changing the command signal reception mode.

  In step S108, the in-vehicle communication device 111 is instructed to execute the first process of the vehicle 102, similarly to the process of step S57 of FIG.

  In step S109, the portable device 112 transmits the portion of the command signal before the transmission mode is changed in the narrowband transmission mode. Specifically, the signal processing unit 152 generates a command signal having the same configuration as the command signal in FIG. 7 in response to the authentication request signal received from the in-vehicle communication device 111, and transmits the command signal via the transmission control unit 153. 145. Further, the signal processing unit 152 notifies the transmission control unit 153 of the change position of the set transmission mode of the command signal.

  Under the control of the transmission control unit 153, the transmission unit 145 performs FSK modulation on the portion of the command signal before the transmission mode is changed with a narrowband maximum frequency shift, and transmits the result via the antenna 146. A predetermined interval is provided between the end of transmission of the authentication signal and the start of transmission of the command signal.

  FIG. 9 shows an example in which the change position of the command signal transmission mode is set in the data portion. Therefore, in this case, the transmission unit 145 performs FSK modulation on the synchronization code portion and the command portion before the data portion, which is the transmission mode change position, with a narrowband maximum frequency shift, and transmits the result via the antenna 146.

  In the following, as shown in FIG. 9, a process when the change position of the command signal transmission mode is set in the data portion will be described.

  In step S110, the signal processing unit 132 of the in-vehicle communication device 111 determines whether or not the part before the change of the command signal transmission mode has been received. Specifically, when receiving the synchronization code part and the command part of the command signal transmitted from the portable device 112 in the process of step S109 via the antenna 121, the receiving part 122 narrows the received parts. Demodulate with maximum frequency deviation of. In addition, the reception unit 122 supplies the synchronization code part and command part of the demodulated command signal to the signal processing part 132 via the reception control part 131. Furthermore, the receiving unit 122 performs phase synchronization based on the synchronization code included in the synchronization code unit. When the above processing is performed within a predetermined time after receiving the authentication signal, the signal processing unit 132 determines that the portion of the command signal before the change of the transmission mode has been received, and the processing proceeds to step S111. move on.

  In step S111, the reception unit 122 of the in-vehicle communication device 111 is changed to the wideband reception mode, similarly to the process in step S6 of FIG.

  In step S112, the portable device 112 transmits the command signal transmission mode after being changed in the wideband transmission mode. Specifically, under the control of the transmission control unit 153, the transmission unit 145 performs FSK modulation on the data unit and the CW unit, which are parts after the command signal transmission mode is changed, with a wideband maximum frequency shift, and the antenna 146 via 146.

  As a result, as shown in FIG. 9, the maximum frequency shift of the FSK modulation is switched in the middle of the response signal, more precisely, in the middle of the command signal constituting the response signal.

  Thereafter, the processing of the portable device 112 returns to step S103, and the processing after step S103 is executed.

  In step S113, the signal processing unit 132 of the in-vehicle communication device 111 determines whether or not a normal response signal has been received. Specifically, when the reception unit 122 of the in-vehicle communication device 111 receives the data part and the CW part of the command signal transmitted from the portable device 112 in the process of step S112 via the antenna 121, those received The part is demodulated with a wideband maximum frequency shift. In addition, the reception unit 122 supplies the demodulated command signal data portion and CW portion to the signal processing unit 132 via the reception control unit 131. The signal processing unit 132 collates the authentication information of the portable device 112 included in the data part of the command signal. Then, if the authentication information is regular authentication information, the signal processing unit 132 determines that a regular command signal has been received, and further includes a regular response signal (that is, a combination of a regular authentication signal and a regular command signal). ) And the process proceeds to step S114.

  In step S114, the in-vehicle communication device 111 is instructed to execute the second process of the vehicle 102, similarly to the process of step S60 of FIG.

  Thereafter, the processing of the in-vehicle communication device 111 ends.

  On the other hand, in step S113, the signal processing unit 132 determines that the normal response signal has not been received when reception of the data part and the CW part of the command signal fails or when authentication of the command signal fails, The processing of the in-vehicle communication device 111 ends.

  In step S110, when the signal processing unit 132 fails to receive the synchronization code part and the command part of the command signal, the signal processing part 132 determines that the part before the change of the transmission mode of the command signal has not been received, and the in-vehicle communication device 111. This process ends.

  Further, in step S106, the signal processing unit 132 determines that the regular authentication signal has not been received when the authentication signal has failed to be received or when the authentication signal has failed to be authenticated. Ends.

  In the case of the pre-authentication method, for example, when it is determined in step S106 that a normal authentication signal has not been received, it is determined in step S110 that the portion of the command signal before the transmission mode change has not been received. In step S113, if it is determined that a regular response signal has not been received, or if the process of step S114 is completed, the process of the in-vehicle communication device 111 returns to step S101, and the processes after step S101 are executed. Is done.

  For example, when the change position of the transmission mode of the command signal is set in the head synchronization code part, the processes in steps S109 and S110 are omitted.

  As described above, in the third embodiment, since the change position of the command signal transmission mode differs for each communication, it becomes more difficult to perform the relay attack.

[Fourth Embodiment of Processing of Communication System 101]
Next, a fourth embodiment of the processing of the communication system 101 will be described with reference to FIGS. 10 and 11. In the fourth embodiment, a response signal is transmitted from the portable device 112 in two parts, that is, an authentication signal and a command signal, and a combination of command signal transmission modes is made variable. Therefore, this embodiment can be applied when the portable device 112 can cope with three or more types of transmission modes.

  FIG. 10 is a flowchart for explaining the fourth embodiment of the processing of the communication system 101, and FIG. 11 is a timing chart showing the signal flow of the communication system 101.

  In step S151, the reception control unit 131 of the in-vehicle communication device 111 initializes the reception mode of the reception unit 122. Thereby, the receiving unit 122 is set to the initial reception mode. Here, the initial reception mode is a reception mode corresponding to the initial transmission mode of the portable device 112, and is a reception mode for demodulating an FSK-modulated signal with the same maximum frequency shift as the initial transmission mode.

  In step S152, an authentication request signal is transmitted from the in-vehicle communication device 111 in the same manner as in step S2 of FIG.

  In step S153, similar to the process in step S3 in FIG. 3, it is determined whether or not the portable device 112 has received the authentication request signal. If it is determined that the authentication request signal has been received, the process proceeds to step S154. move on.

  In step S154, the signal processing unit 152 of the portable device 112 sets a command signal transmission mode. Specifically, the signal processing unit 152 selects one of the transmission modes excluding the initial transmission mode from among the transmission modes that can be supported by the transmission unit 145, and sets the transmission mode for the command signal. .

  The command signal transmission mode may be set randomly, for example, or may be set according to a predetermined rule.

  In step S155, the portable device 112 transmits an authentication signal including the setting contents in the initial transmission mode. Specifically, the signal processing unit 152 generates an authentication signal for the authentication request signal received from the in-vehicle communication device 111 and supplies the authentication signal to the transmission unit 145 via the transmission control unit 153.

  For example, as shown in FIG. 11, the authentication signal is composed of blocks of a synchronization code part and an authentication / setting data part.

  The synchronization code part is the same block as the synchronization code part of the response signal in FIG.

  The authentication / setting data section is a block including authentication information of the portable device 112 and setting information of a command signal transmission mode.

  Then, under the control of the transmission control unit 153, the transmission unit 145 performs FSK modulation on the authentication signal with the maximum frequency shift in the initial transmission mode, and transmits the signal via the antenna 146. Thereby, the in-vehicle communication device 111 is notified of the transmission mode of the command signal using the authentication signal.

  In step S156, the signal processing unit 132 of the in-vehicle communication device 111 determines whether a regular authentication signal has been received. Specifically, when the receiving unit 122 of the in-vehicle communication device 111 receives the authentication signal transmitted from the portable device 112 in the process of step S155 via the antenna 121, the received authentication signal is the maximum in the initial reception mode. Demodulate with frequency shift. In addition, the reception unit 122 supplies the demodulated authentication signal to the signal processing unit 132 via the reception control unit 131. Furthermore, the receiving unit 122 performs phase synchronization based on the synchronization code included in the synchronization code portion of the authentication signal. In addition, the signal processing unit 132 collates the authentication information of the portable device 112 included in the authentication data unit, and determines that the normal authentication signal has been received when the authentication information is normal authentication information. Proceed to step S157.

  In step S157, the in-vehicle communication device 111 changes the reception mode of the reception unit 122 to a reception mode corresponding to the notified transmission mode. Specifically, the signal processing unit 132 notifies the reception control unit 131 of the transmission mode of the command signal indicated in the authentication / setting data unit of the authentication signal. The reception control unit 131 changes the reception mode of the reception unit 122 to a reception mode corresponding to the notified transmission mode. As a result, the receiving unit 122 is set to a reception mode that demodulates a signal with the same maximum frequency shift as the notified transmission mode.

  In step S158, the in-vehicle communication device 111 is instructed to execute the first process of the vehicle 102, similarly to the process of step S57 of FIG.

  In step S159, the portable device 112 transmits the command signal in the set transmission mode. Specifically, the signal processing unit 152 generates a command signal having the same configuration as the command signal in FIG. 7 in response to the authentication request signal received from the in-vehicle communication device 111, and transmits the command signal via the transmission control unit 153. 145. In addition, the signal processing unit 152 notifies the transmission control unit 153 of the set transmission mode.

  The transmission unit 145 performs FSK modulation on the command signal with the maximum frequency shift in the set transmission mode under the control of the transmission control unit 153, and transmits the command signal via the antenna 146. A predetermined interval is provided between the end of transmission of the authentication signal and the start of transmission of the command signal.

  Accordingly, as shown in FIG. 11, the maximum frequency shift of the FSK modulation is switched in the middle of the response signal, more strictly, between the authentication signal and the command signal constituting the response signal.

  Thereafter, the process of the portable device 112 returns to step S153, and the processes after step S153 are executed.

  In step S160, the signal processing unit 132 of the in-vehicle communication device 111 determines whether or not a normal response signal has been received. Specifically, when the reception unit 122 of the in-vehicle communication device 111 receives the command signal transmitted from the portable device 112 through the antenna 121 in the process of step S159, the received command signal is set in the set reception mode. Demodulate with maximum frequency shift. The receiving unit 122 also supplies the demodulated command signal to the signal processing unit 132 via the reception control unit 131. The signal processing unit 132 collates the authentication information of the portable device 112 included in the data part of the command signal. Then, if the authentication information is regular authentication information, the signal processing unit 132 determines that a regular command signal has been received, and further includes a regular response signal (that is, a combination of a regular authentication signal and a regular command signal). ) Is received, and the process proceeds to step S161.

  In step S161, the in-vehicle communication device 111 is instructed to execute the second process of the vehicle 102, as in the process of step S60 of FIG.

  Thereafter, the processing of the in-vehicle communication device 111 ends.

  On the other hand, if it is determined in step S156 that a normal authentication signal has not been received, or if it is determined in step S160 that a normal response signal has not been received, the processing of the in-vehicle communication device 111 ends.

  In the case of the pre-authentication method, for example, if it is determined in step S156 that a normal authentication signal has not been received, if it is determined in step S160 that a normal response signal has not been received, or step S161. When the process is completed, the process of the in-vehicle communication device 111 returns to step S151, and the processes after step S151 are executed.

  As described above, in the fourth embodiment, the command signal transmission mode is different for each communication. In other words, the maximum frequency shift when the command signal is FSK modulated is different for each communication. Implementation becomes more difficult.

[Fifth Embodiment of Processing of Communication System 101]
Next, a fifth embodiment of the process of the communication system 101 will be described with reference to FIGS. The fifth embodiment is a combination of the third embodiment and the fourth embodiment.

  FIG. 12 is a flowchart for explaining the fifth embodiment of the processing of the communication system 101, and FIG. 13 is a timing chart showing the signal flow of the communication system 101.

  In step S201, the reception mode of the reception unit 122 of the in-vehicle communication device 111 is initialized as in the process of step S151 in FIG.

  In step S202, an authentication request signal is transmitted from the in-vehicle communication device 111 as in the process of step S2 of FIG.

  In step S203, as in the process of step S3 of FIG. 3, it is determined whether or not the portable device 112 has received the authentication request signal. If it is determined that the authentication request signal has been received, the process proceeds to step S204. move on.

  In step S204, the signal processing unit 152 of the portable device 112 sets a command signal transmission mode and a change position. Specifically, the signal processing unit 152 sets the command signal transmission mode in the same manner as the processing in step S154 of FIG. In addition, the signal processing unit 152 sets a command signal transmission mode change position in the same manner as in step S104 of FIG.

  In step S205, the portable device 112 transmits an authentication signal including the setting contents in the initial transmission mode. Specifically, the signal processing unit 152 generates an authentication signal for the authentication request signal received from the in-vehicle communication device 111 and supplies the authentication signal to the transmission unit 145 via the transmission control unit 153.

  For example, as shown in FIG. 13, the authentication signal is composed of blocks of a synchronization code part and an authentication / setting data part.

  The synchronization code part is the same block as the synchronization code part of the response signal in FIG.

  The authentication / setting data section is a block including authentication information of the portable device 112, and command signal transmission mode and change position setting information.

  Then, under the control of the transmission control unit 153, the transmission unit 145 performs FSK modulation on the authentication signal with the maximum frequency shift in the initial transmission mode, and transmits the signal via the antenna 146. Thereby, the transmission mode and change position of the command signal are notified to the in-vehicle communication device 111 using the authentication signal.

  In step S206, as in the process of step S156 of FIG. 10, it is determined whether or not the in-vehicle communication device 111 has received a normal authentication signal. If it is determined that a regular authentication signal has been received, the process proceeds to step S207.

  In step S207, the in-vehicle communication device 111 sets a command signal reception mode and a change position. Specifically, the signal processing unit 132 notifies the reception control unit 131 of the transmission mode and change position of the command signal indicated in the authentication / setting data unit of the authentication signal. The reception control unit 131 stores the reception mode corresponding to the notified transmission mode as the reception mode after changing the command signal. The reception control unit 131 stores the notified change position as the change position of the command signal reception mode.

  In step S208, the in-vehicle communication device 111 is instructed to execute the first process of the vehicle 102, similarly to the process of step S57 of FIG.

  In step S209, the portable device 112 transmits the part of the command signal before the transmission mode is changed in the initial transmission mode. Specifically, the signal processing unit 152 generates a command signal having the same configuration as the command signal in FIG. 7 in response to the authentication request signal received from the in-vehicle communication device 111, and transmits the command signal via the transmission control unit 153. 145. Further, the signal processing unit 152 notifies the transmission control unit 153 of the change position of the set transmission mode of the command signal and the changed transmission mode.

  Under the control of the transmission control unit 153, the transmission unit 145 performs FSK modulation on the portion of the command signal before the change of the transmission mode with the maximum frequency shift in the initial transmission mode, and transmits the result via the antenna 146. A predetermined interval is provided between the end of transmission of the authentication signal and the start of transmission of the command signal.

  FIG. 13 shows an example in which the change position of the command signal transmission mode is set in the data portion. Therefore, in this case, the transmission unit 145 performs FSK modulation with the maximum frequency shift in the initial transmission mode, and transmits the synchronization code unit and the command unit in front of the data unit, which is the transmission mode change position, via the antenna 146. .

  Hereinafter, as shown in FIG. 13, processing when the change position of the command signal transmission mode is set in the data portion will be described.

  In step S210, the signal processing unit 132 of the in-vehicle communication device 111 determines whether or not the part before the change of the command signal transmission mode has been received. Specifically, when receiving the synchronization code part and the command part of the command signal transmitted from the portable device 112 in the process of step S209 via the antenna 121, the receiving part 122 initially receives the received parts. Demodulate with maximum frequency shift in mode. In addition, the reception unit 122 supplies the synchronization code part and command part of the demodulated command signal to the signal processing part 132 via the reception control part 131. Furthermore, the receiving unit 122 performs phase synchronization based on the synchronization code included in the synchronization code unit. When the above processing is performed within a predetermined time after receiving the authentication signal, the signal processing unit 132 determines that the portion of the command signal before the change of the transmission mode has been received, and the processing proceeds to step S211. move on.

  In step S211, the reception mode of the reception unit 122 of the in-vehicle communication device 111 is changed to the reception mode corresponding to the notified transmission mode, as in the process of step S157 of FIG.

  In step S212, the command signal transmission mode after the change is transmitted in the set transmission mode. Specifically, under the control of the transmission control unit 153, the transmission unit 145 modulates the data part and the CW part, which are parts after the command signal transmission mode is changed, with the maximum frequency deviation in the set transmission mode. And transmit via the antenna 146.

  As a result, as shown in FIG. 13, the maximum frequency shift of the FSK modulation is switched in the middle of the response signal, more precisely, in the middle of the command signal constituting the response signal.

  Thereafter, the process of the portable device 112 returns to step S203, and the processes after step S203 are executed.

  In step S213, the signal processing unit 132 of the in-vehicle communication device 111 determines whether a normal response signal has been received. Specifically, when the receiving unit 122 of the in-vehicle communication device 111 receives the data part and the CW part of the command signal transmitted from the portable device 112 in the process of step S212 via the antenna 121, those received The part is demodulated with the maximum frequency shift in the set reception mode. In addition, the reception unit 122 supplies the demodulated command signal data portion and CW portion to the signal processing unit 132 via the reception control unit 131. The signal processing unit 132 collates the authentication information of the portable device 112 included in the data part of the command signal. Then, if the authentication information is regular authentication information, the signal processing unit 132 determines that a regular command signal has been received, and further includes a regular response signal (that is, a combination of a regular authentication signal and a regular command signal). ) And the process proceeds to step S214.

  In step S214, the in-vehicle communication device 111 is instructed to execute the second process of the vehicle 102, similarly to the process of step S60 of FIG.

  Thereafter, the processing of the in-vehicle communication device 111 ends.

  On the other hand, if it is determined in step S206 that a normal authentication signal has not been received, if it is determined in step S210 that a portion of the command signal before the transmission mode change has been received, or in step S213, When it is determined that the regular response signal has not been received, the processing of the in-vehicle communication device 111 ends.

  In the case of the pre-authentication method, if it is determined in step S206 that a regular authentication signal has not been received, or if it is determined in step S210 that the portion of the command signal before the transmission mode change has not been received, If it is determined in step S213 that a normal response signal has not been received, or if the process of step S214 is completed, the process of the in-vehicle communication device 111 returns to step S201, and the processes after step S201 are executed. .

  As described above, in the fifth embodiment, since the transmission mode and change position of the command signal are different for each communication, it is more difficult to perform the relay attack.

<2. Modification>
Hereinafter, modifications of the above-described embodiment of the present invention will be described.

[Modification 1: Modification concerning transmission mode and reception mode]
The combination and order of the transmission mode and the reception mode described above are examples, and can be arbitrarily changed. For example, the order of the narrowband transmission mode and the wideband transmission mode can be changed.

  In the above description, the example in which the transmission mode of the response signal is changed only once has been described in the first embodiment. However, the response signal transmission mode may be changed twice or more. Similarly, in the third embodiment and the fifth embodiment, the command signal transmission mode may be changed twice or more. In addition, when the transmission mode is changed twice or more, the two types of transmission modes can be switched alternately, and the transmission mode can be switched from among three or more types.

  Further, in the above description, in the second to fifth embodiments, the example in which the response signal is divided into two signals, that is, the authentication signal and the command signal, has been shown. May be. Further, when transmitting in three or more parts, it is possible to change the transmission mode and change position of the third and subsequent signals in the same manner as the command signal described above.

  In the above description, in the first, third, and fifth embodiments, the example in which the transmission mode is changed in units of blocks of the response signal or the command signal has been described. However, the transmission is not necessarily performed at the boundary between adjacent blocks. It is not necessary to change the mode, and it is possible to change it in the middle of the block. For example, it is possible to change the transmission mode in the middle of the synchronization code part, or to add a dummy signal at the beginning or end of the command part and change the transmission mode in the middle of the dummy signal. .

  Further, for example, in the portable device 112, the maximum frequency shift of the FSK modulation can be set to an arbitrary value, the set value is notified to the in-vehicle communication device 111, and the set value notified in the in-vehicle communication device 111 is notified. The maximum frequency deviation at the time of demodulation may be set to the same value as.

  In the above description, the example of changing the transmission mode of the response signal transmitted from the portable device 112 to the in-vehicle communication device 111 is shown. However, the authentication request transmitted from the in-vehicle communication device 111 to the portable device 112 by the same method. It is also possible to change the transmission mode while FSK-modulating the signal. In this case as well, the relay attack can be made difficult to execute, as in the case of changing the response signal transmission mode.

[Modification 2: Modification regarding apparatus configuration]
Further, the configuration of the in-vehicle communication device 111 is not limited to the example illustrated in FIG. 1 and can be variously changed. For example, the reception control unit 131 and the transmission control unit 133 can be provided outside the control unit 123, and the reception unit 122 and the transmission unit 124 can be provided inside the control unit 123. Further, for example, the reception unit 122 and the reception control unit 131 can be combined, or the transmission unit 124 and the transmission control unit 133 can be combined. Further, for example, the reception unit 122 and the transmission unit 124 can be combined. It is also possible to divide the part that performs transmission processing and the part that performs reception processing of the in-vehicle communication device 111 into two devices.

  Furthermore, the configuration of the portable device 112 is not limited to the example shown in FIG. 1 and can be variously changed. For example, the reception control unit 151 and the transmission control unit 153 can be provided outside the control unit 144, and the reception unit 142 and the transmission unit 145 can be provided inside the control unit 144. Further, for example, the reception unit 142 and the reception control unit 151 can be combined, or the transmission unit 145 and the transmission control unit 153 can be combined. Further, for example, the reception unit 142 and the transmission unit 145 can be combined.

  The number of portable devices 112 is not limited to one, and two or more portable devices 112 can be provided. The number of in-vehicle communication devices 111 is not limited to one, and two or more in-vehicle communication devices 111 can be provided.

[Modification 3: Other Modifications]
Furthermore, the type of vehicle to which the present invention is applied is not particularly limited. For example, the present invention can be applied not only to four-wheeled vehicles such as automobiles but also to two-wheeled vehicles and other types of vehicles.

  The present invention can also be applied to a wireless communication system other than a vehicle. In particular, the present invention is effective when applied to a system in which the other communication device automatically transmits a response signal in response to a request from one communication device, for example. For example, in a system in which when a building door is operated, an authentication request signal is transmitted from a communication device provided in the building to the portable device, and the door is unlocked or locked according to a response signal from the portable device. It is valid.

[Computer configuration example]
The series of processes described above can be executed by hardware or can be executed by software. When a series of processing is executed by software, a program constituting the software is installed in the computer. Here, the computer includes, for example, a general-purpose personal computer capable of executing various functions by installing various programs by installing a computer incorporated in dedicated hardware.

  The program executed by the computer can be provided by being recorded on a removable medium such as a package medium. The program can be provided via a wired or wireless transmission medium such as a local area network, the Internet, or digital satellite broadcasting.

  In addition, the program can be installed in advance in, for example, a ROM or a storage unit.

  The program executed by the computer may be a program that is processed in time series in the order described in this specification, or in parallel or at a necessary timing such as when a call is made. It may be a program for processing.

  In this specification, the system means a set of a plurality of components (devices, modules (parts), etc.), and it does not matter whether all the components are in the same housing. Accordingly, a plurality of devices housed in separate housings and connected via a network and a single device housing a plurality of modules in one housing are all systems. .

  Furthermore, the embodiments of the present invention are not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

  In addition, each step described in the above flowchart can be executed by being shared by a plurality of apparatuses in addition to being executed by one apparatus.

  Further, when a plurality of processes are included in one step, the plurality of processes included in the one step can be executed by being shared by a plurality of apparatuses in addition to being executed by one apparatus.

DESCRIPTION OF SYMBOLS 101 Communication system 102 Vehicle 103 Repeater 111 In-vehicle communication device 112 Portable machine 122 Reception part 123 Control part 124 Transmission part 131 Reception control part 132 Signal processing part 133 Transmission control part 134 Vehicle control part 142 Reception part 144 Control part 145 Transmission part 151 Reception control unit 152 Signal processing unit 153 Transmission control unit

Claims (11)

In a communication system in which a first communication device and a second communication device perform wireless communication,
The first communication device is:
A first transmission unit that FSK-modulates and transmits a signal to the second communication device;
A first transmission control unit for controlling the first transmission unit,
The second communication device is:
A first receiver for receiving and demodulating a signal from the first communication device;
The first transmission control unit performs control so as to change the maximum frequency shift in the middle when FSK-modulated and transmitted a predetermined first signal,
When the first receiving unit receives and demodulates the first signal, the maximum frequency shift is changed during the FSK modulation of the first signal. A communication system that changes the shift. The first communication device is:
A second receiver for receiving and demodulating a signal from the second communication device;
The second communication device is:
Provided in the vehicle,
A second transmitter for modulating and transmitting a signal to the first communication device;
A second transmission control unit for controlling the second transmission unit;
A vehicle control unit for controlling the processing of the vehicle,
The second transmission control unit controls to transmit a predetermined second signal when a predetermined operation is performed on the vehicle or periodically.
The first transmission control unit controls to transmit the first signal as a response signal to the second signal;
The communication system according to claim 1, wherein the vehicle control unit instructs execution of predetermined processing of the vehicle when the legitimate first signal is received from the first communication device. The first communication device is:
Provided in the vehicle,
A second receiver for receiving and demodulating a signal from the second communication device;
A vehicle control unit for controlling the processing of the vehicle,
The second communication device is:
A second transmitter for modulating and transmitting a signal to the first communication device;
A second transmission control unit for controlling the second transmission unit;
The first transmission control unit performs control so that the first signal is transmitted when a predetermined operation is performed on the vehicle or periodically.
The second transmission control unit controls to transmit a second signal as a response signal to the first signal;
The communication system according to claim 1, wherein the vehicle control unit instructs execution of predetermined processing of the vehicle when receiving the regular second signal from the second communication device. The communication system according to any one of claims 1 to 3, wherein the first transmission control unit controls the first signal to be divided into at least a first divided signal and a second divided signal. . The first transmission control unit performs FSK modulation on the first divided signal with a predetermined first maximum frequency shift, and with a predetermined second maximum frequency shift different from the first maximum frequency shift. Controlling the second divided signal to be FSK modulated;
The first reception unit demodulates the first divided signal with the first maximum frequency shift, and demodulates the second divided signal with the second maximum frequency shift. Communication system. The first transmission control unit sets a change position of a maximum frequency shift when the second divided signal is FSK-modulated, and the set change position is set to the second communication by the first divided signal. Notifying the device and controlling the maximum frequency shift when the second divided signal is FSK modulated to be changed at the change position,
The communication system according to claim 4, wherein the first reception unit demodulates the second signal by changing a maximum frequency shift at the change position notified by the first divided signal. The first transmission control unit sets a second maximum frequency deviation different from a predetermined first maximum frequency deviation, and the set second maximum frequency deviation is determined by the first divided signal. Notifying the second communication device, and FSK-modulating the first divided signal with the first maximum frequency deviation, and FSK-modulating the second divided signal with the second maximum frequency deviation. Control to
The first receiving unit demodulates the first divided signal with the first maximum frequency deviation, and the second maximum frequency deviation notified by the first divided signal with the second maximum frequency deviation. The communication system according to claim 4 or 6, wherein the divided signal is demodulated. The first transmission control unit performs control so as to change a maximum frequency shift at a predetermined position of the first signal when FSK-modulating the first signal;
4. The first receiving unit changes a maximum frequency shift at the predetermined position set in advance of the first signal when demodulating the first signal. 5. Communication system. The first communication device is:
A second receiver for receiving and demodulating a signal from the second communication device;
The second communication device is:
Provided in the vehicle,
A second transmitter for modulating and transmitting a signal to the first communication device;
A second transmission control unit for controlling the second transmission unit;
A vehicle control unit for controlling the processing of the vehicle,
The second transmission control unit controls to transmit a predetermined second signal when a predetermined operation is performed on the vehicle or periodically.
The first transmission control unit controls the first signal to be divided into at least the first divided signal and the second divided signal and transmitted as a response signal to the second signal,
When the vehicle control unit receives the regular first divided signal from the first communication device, the vehicle control unit instructs the vehicle to execute a predetermined first process, and the vehicle communication unit issues a regular operation from the first communication device. The communication system according to claim 1, wherein when the second divided signal is received, execution of predetermined second processing of the vehicle is instructed. In communication devices that perform wireless communication with other communication devices,
A transmission unit that FSK-modulates and transmits a signal to the other communication device;
A transmission control unit for controlling the transmission unit,
The said transmission control part is a communication apparatus which controls so that the maximum frequency deviation may be changed on the way, when a predetermined signal is FSK modulated and transmitted. In communication devices that perform wireless communication with other communication devices,
A receiving unit that receives and demodulates an FSK-modulated signal from the other communication device;
When the receiving unit receives and demodulates a predetermined signal from the other communication device, the maximum frequency shift is changed during the FSK modulation of the predetermined signal in the other communication device. A communication device that changes the maximum frequency deviation according to

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