WO2014131074A1

WO2014131074A1 - System and method for determining a user device location

Info

Publication number: WO2014131074A1
Application number: PCT/AU2013/000182
Authority: WO
Inventors: Kevin Frank COHEN; Jesse WANG; Robin Michael Braun
Original assignee: Locamate Pty Ltd
Priority date: 2013-02-28
Filing date: 2013-02-28
Publication date: 2014-09-04

Abstract

A system determines a user's location by receiving communication signals from a user device carried by the user. The communication signals sent from the user devices to wireless communications network base stations may be received by location sensors that are able to determine angles of arrival of the communication signals and, in turn, origin locations of the communication signals. A single angle of arrival may be sufficient to unambiguously determine the position of the user device in one axis of a three dimensional space. A second angle of arrival may be determined from a second pair of antennas to unambiguously determine the position of the user device in a second axis of the three dimensional space. Similarly a third angle of arrival may be determined from a third pair of antennas to unambiguously determine the position of the user device in the last axis of the three dimensional space.

Description

SYSTEM AND METHOD FOR DETERMINING A USER DEVICE LOCATION

BACKGROUND

Field

[0001] The present disclosure relates to determining the locations of user devices. Background

[0002] Wireless communication technologies and devices are widely deployed and used, including but not limited to voice calls and access to data on the Internet. As the number of deployed user devices, such as, for example, smartphones or the like, increases, there will be increased opportunities for stores, merchants, and other businesses to improve customer service and business efficiency using location data from user devices in the vicinity. Existing location determination systems vary in physical design, type of signal used, accuracy, complexity, and cost. Many systems require the extensive installation of additional infrastructure.

[0003] Proximity methods usually use densely deployed sensors, each having a known location. A proximity sensor provides location information for a mobile target when the target comes into proximity and is detected by the sensor. If the target is detected by multiple sensors, kNN (k Nearest Neighbors) or weighted kNN algorithms can be performed to find an averaged relative location. Proximity methods usually require the installation of a large number of proximity sensors.

[0004] Signal strength methods may convert a Received Signal Strength Indicator (RSSI) from a receiver into relative distance estimations using a technique called lateration, and then apply triangulation algorithms from three or more sensors to estimate the absolute location of a signal transmitter. However for indoor environments, there is not always line-of- sight between a transmitter and a receiver, therefore radio propagation suffers from multipath effects.

[0005] In this context, there is a need for determining user device locations with high accuracy and without the extensive installation of additional infrastructure.

SUMMARY

[0006] The following presents a simplified summary of one or more embodiments in order to provide a basic understanding of such embodiments. This summary is not an extensive overview of all contemplated embodiments, and is intended to neither identify key or critical elements of all embodiments nor delineate the scope of any or all embodiments. Its sole purpose is to present some concepts of one or more embodiments in a simplified form as a prelude to the more detailed description that is presented later. In accordance with one or more aspects of the embodiments described herein, there is provided a system and method for determining a user device location.

[0007] In one embodiment of a method for determining a user location, a system may generate a reference signal. The system may receive a first signal at a first antenna and a second signal at a second antenna. The system may combine an in-phase component of the reference signal to the first signal to form a first alpha signal and combine a quadrature component of the reference signal to the first signal to form a first beta signal. The system may combine the in-phase component of the reference signal to the second signal to form a second alpha signal and combine the quadrature component of the reference signal to the second signal to form a second beta signal. The system may determine a first angle of arrival based on the first alpha signal, the first beta signal, the second alpha signal, and the second beta signal.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 illustrates features of a system for determining a user device location;

[0009] FIG. 2 is a block diagram illustrating an example of a system for determining a user device location;

[0010] FIG. 3 is a cross-sectional illustration of details regarding determining a user device location using angles of arrival;

[0011] FIG. 4 illustrates an example schematic for the determination of angles of arrival;

[0012] FIG. 5 illustrates an example schematic for the determination of angles of arrival;

[0013] FIG. 6A illustrates an example methodology for determining a user device location;

[0014] FIG. 6B shows further aspects of the methodology of FIG. 6A;

[0015] FIG. 7A illustrates an embodiment of an apparatus for determining a user device location; and

[0016] FIG. 7B shows further aspects of the apparatus of FIG. 7A. DETAILED DESCRIPTION

[0017] Various aspects are described with reference to the drawings. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more aspects. It may be evident, however, that the various aspects may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing these aspects. The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

[0018] System and methods for determining user device location are described herein. Various user devices (e.g., smartphones, portable music players, or other personal computing devices with wireless capability) support wireless communication networks such as wireless wide area networks (WWANs) and wireless local area networks (WLANs). The terms "network" and "system" are often used interchangeably. A WLAN may implement a radio technology such as IEEE 802.11 (Wi-Fi) or the like. Communication signals sent from the user devices to wireless communications network base stations may be received by location sensors that are able to determine angles of arrival of the communication signals and, in turn, origin locations of the communication signals. For example, a mobile phone carried by a shopper in a shopping center may support Wi-Fi radio technology and may communicate with nearby Wi-Fi access points. The mobile phone may "find hot spots" by transmitting a signal for the purpose of being received by various nearby Wi-Fi access points. The signal may be received by location sensors configured to determine the mobile phone's location by first determining an angle of arrival of the signal. This example method may be applied to locate any existing user device seeking access to a nearby Wi-Fi access points without the need for the user device to change its standard behavior or perform additional actions.

[0019] FIG. 1 illustrates features of a system 100 for determining a user device location. User devices 120 routinely communicate with an access point 130. The user device 120 may include a radio frequency identification (RFID) tag or the like. For example, the access point 130 may be a Wi-Fi access point, cellular base station, Bluetooth access point, or the like. The user device 120 may receive downlink signals 102 from the access point 130. The user device 120 may also transmit device signals 104 to the access point 130. In some aspects, the received signals 102 and the transmitted device signals 104 by the user device 120 may be Wi-Fi signals (802.11b, 802.1 lg, or 802.11η), Bluetooth signals, or the like. In related aspects, the signals may be in the 2.4 GHz, 5GHz, 433mHz, 915mHz, or other frequency blocks. In some aspects, the device signals 104 may be over a plurality of frequency blocks. The device signals 104 may be detected by a nearby location sensor 110.

[0020] FIG. 2 is a block diagram 200 illustrating an example of a system for determining a user device location. The user device 120 may transmit device signals 104 which are received by one or more location sensors 110. The location sensors 110 may then transmit location data 106 of the user devices 120 to a location server 140 for analysis and application. In one approach, the location sensor 110 determines the angles of arrival of the device signals 104 received at the location senor 110 and transmits the angle of arrival information as the location data 106 to the location server 140. In another approach, the location sensor 110 may not determine the angles of arrival onsite, but transmits the location data 106 based on the device signals 104 to the location server 140. The location server 140 may then determine the angles of arrival based on the location data 106.

[0021] The location server 140 may additionally determine and track identities of multiple user devices 120. For example, with Wi-Fi signals as the device signals 104, each device signal 104 includes the user device's MAC address information embedded inside the header of MPDU frames in the Wi-Fi protocol to uniquely identify different user devices 120 transmitting Wi-Fi signals. For tracking signals other than Wi-Fi, other identifying information (e.g. RFID or the like) may be used to determine and track the source of those signals.

[0022] Examples of the use of systems and methods for determining a user device location may involve: tracking the movement of visitors in a shopping center or office building; sending special offers and deals to customers depending on their location in a shopping center; alerting retail store staff to move to an area where there is deemed to be a "queue" (i.e., a defined number of customers); notifying staff that a VIP has entered an area.

[0023] Benefits to retailers may include the ability to market products and services relevant to the location of specific customers carrying user devices 120 transmitting device signals 104. For example, a unique identifier for a specific customer's user device 120, such as a MAC address, may be detected and associated with the specific customer's personal details. The specific customer may have an application on the specific customer's user device 120 that allows deals or other information to be received.

[0024] Another benefit to retailers may also include the ability to monitor, via the system for determining a user device location 100, the behavior of customers in response to promotional activity. The benefit to retailers may also include the ability to gather customer analytics for customers, including: (a) how often customers visit the store; (b) how long they spend in the store; (c) what they purchase; (d) whether the customer has visited before and the average gap between visits; and (e) the measured profitability of a given promotional activity.

[0025] FIG. 3 is a cross-sectional illustration 300 of details regarding determining a user device location using angles of arrival. In one approach, two antennas 112a and 112b are mounted to a flat ceiling surface 310. In one approach, the two antennas 112a and 112b may be separated by a distance of half a wavelength (λ/2) of the device signal 104. Although any antenna separation distance may be used, it may require means of removing ambiguities in the measured angles. For example, if the device signal 104 is at 2.45GHz, the wavelength λ of the device signal 104 is 12cm, and the distance between the antennas 112a and 112b may be 6cm. The user device 120 may transmit a device signal 104 in various directions. The device signal 104 may be received as 104a by antenna 112a. The same device signal 104 may be received as 104b by antenna 112b. It may be assumed that the device signal 104a is identical to device signal 104b and that device signal 104a was simultaneously transmitted from the user device 120 as the device signal 104b.

[0026] It may be assumed that an angle of arrival (β) of device signal 104a at antenna 112a is approximately equal to an angle of arrival (β) of device signal 104b at antenna 112b because of the insignificance of the antenna separation distance (λ/2) against a distance of the user device 120 from the antennas 112. For example, if the user device 120 is located perpendicular to a line formed from the antenna 112a and 112b then the angles of arrival (β) at antenna 112a and antenna 112b are both 90 degrees. In this case, the device signal 104a is received at antenna 112a at the same time that the device signal 104b is received at antenna 112b. However, if the angle of arrival (β) is less than 90 degrees, one of the antennas 112 will receive the device signal 104 sooner than the other antenna 112 due to a distance difference (D) from the user device 120 causing a delay.

[0027] The distance difference (D) may be obtained from a measurement of the phase difference (Θ) between the device signals 104a and 104b arriving at antenna 112a and antenna 112b. If phase is measured in radians, then the distance difference (D) may be calculated:

D (Equation 1).

[0028] The antenna separation distance of half a wavelength (λ/2) considerably simplifies the calculation of the angle of arrival (β):

(Equation 2).

[0029] The antenna separation distance may also be set to a multiple of half a wavelength (ηλ/2) to retain high accuracy in the calculation of the angle of arrival (β).

[0030] A single (first) angle of arrival may be sufficient to unambiguously determine the position of the user device 120 in one (first) axis of a three dimensional space, where the user device 120 may be somewhere along a first cone shaped surface traced by the first angle of arrival on the one axis. A second angle of arrival may be determined from a second pair of antennas to unambiguously determine the position of the user device 120 in a second axis of the three dimensional space, wherein the user device may be somewhere along the intersection of the first cone shaped surface and a second cone shaped surface traced by the second angle of arrival on the second axis. Similarly a third angle of arrival may be determined from a third pair of antennas to unambiguously determine the position of the user device 120 in the last axis of the three dimensional space.

[0031] FIG. 4 illustrates an example schematic 400 for determination of angles of arrival. In this example, antenna 112a and antenna 112b form the first pair of antennas and, optionally, antenna 112c and antenna 112d form the second pair of antennas. The line between antenna 112a and antenna 112b is perpendicular to the line between antenna 112c and antenna 112d. In one approach, this configuration of four antennas 112 may be packaged into one location sensor 110. This location sensor 110 allows the location of the user device 120 to be determined along two perpendicular axis of the three dimensional space. For example, if the location sensor 110 is mounted on a ceiling of an interior space and if the user device 120 is assumed to be carried by a person one meter from the floor, then the approximate location of the user device 120 may be determined along all three axis of the three dimensional space.

[0032] To reduce cost and complexity of the post processing of the device signal 104, the antenna 112a and antenna 112c may optionally be coupled to a single RF switch 420 in the use of two pairs of antennas with a single prost processing circuit. The RF switch 420 may function to rapidly alternate input from either the antenna 112a or the antenna 112c. Similarly the antenna 112b and antenna 112d may be coupled to a single RF switch 420. The RF switch 420 may function to rapidly alternate input from either the antenna 112b or the antenna 112d and thus allows two pairs of antennas to use a single post processing circuit. The RF switch 420 may be coupled to a zero-IF receiver 410. The zero-IF receiver 410 may output to analog to digital converters 430 leading to a digital processor 440.

[0033] FIG. 5 illustrates further details of the schematic 400 of FIG. 4 by showing the internal circuits of the zero-IF (or near zero-IF) receiver 410. The device signal 104 from each of the antennas 112a-d passes through a RF switch 420 then a splitter 550. A local oscillator 550 generates a local reference signal at an intermediate frequency. In some aspects, the intermediate frequency of the local reference signal may be configured to be at or near the frequency of the received device signal 104. A splitter 560 splits the local reference signal into two identical signals. One of the two split local reference signals is an in-phase component of the local reference signal. The other split local reference signal travels through a 90 degree phase shifter to become a quadrature component of the local reference signal. Other splitters 560 split each device signal 104 into two identical signals.

[0034] A signal mixer 570 combines, such as by multiplying, a device signal 104 from antenna 112a with the in-phase component of the local reference signal to form a first alpha signal 590. A signal mixer 570 combines, such as by multiplying, a device signal 104 from antenna 112a with the quadrature component of the local reference signal to form a first beta signal 592. A signal mixer 570 combines, such as by multiplying, a device signal 104 from antenna 112b with the in-phase component of the local reference signal to form a second alpha signal 594. A signal mixer 570 combines, such as by multiplying, a device signal 104 from antenna 112b with the quadrature component of the local reference signal to form a second beta signal 596. [0035] Optionally, in the use of two pairs of antennas with a single post processing circuit, the device signals from antenna 112c and antenna 112d are processed with the same zero-IF receiver 410. The zero-IF receiver 410 may alternate between processing one of the two pairs of antennas. A signal mixer 570 combines, such as by multiplying, a device signal 104 from antenna 112c with the in-phase component of the local reference signal to form a third alpha signal 590. A signal mixer 570 combines, such as by multiplying, a device signal 104 from antenna 112c with the quadrature component of the local reference signal to form a third beta signal 592. A signal mixer 570 combines, such as by multiplying, a device signal 104 from antenna 112d with the in- phase component of the local reference signal to form a fourth alpha signal 594. A signal mixer 570 combines, such as by multiplying, a device signal 104 from antenna 112d with the quadrature component of the local reference signal to form a fourth beta signal 596.

[0036] In related aspects, the first alpha signal 590, the first beta signal 592, the second alpha signal 594, and the second beta signal 596 may each be coupled to low pass filters 430 which may be coupled to analog to digital converters 430 to be converted into digital signals. The analog to digital converters 430 output to a digital processor 440.

[0037] Further circuitry may be included at or outside the processor 440 to determine the MAC address or other such identifying information of the user device, and provide an overall operating system.

[0038] In view of exemplary systems shown and described herein, methodologies that may be implemented in accordance with the disclosed subject matter, will be better appreciated with reference to various flow charts. While, for purposes of simplicity of explanation, methodologies are shown and described as a series of acts/blocks, it is to be understood and appreciated that the claimed subject matter is not limited by the number or order of blocks, as some blocks may occur in different orders and/or at substantially the same time with other blocks from what is depicted and described herein. Moreover, not all illustrated blocks may be required to implement methodologies described herein. It is to be appreciated that functionality associated with blocks may be implemented by software, hardware, a combination thereof or any other suitable means (e.g., device, system, process, or component). Additionally, it should be further appreciated that methodologies disclosed throughout this specification are capable of being stored on an article of manufacture to facilitate transporting and transferring such methodologies to various devices. Those skilled in the art will understand and appreciate that a methodology could alternatively be represented as a series of interrelated states or events, such as in a state diagram.

[0039] In accordance with one or more aspects of the embodiments described herein, with reference to FIG. 6A, there is shown a methodology 200 for determining a user device location. The method 600, operable by the network entity or the like or component(s) thereof, may involve, at 610, generating a reference signal. The method 600 may involve, at 620, receiving a first signal 104a at a first antenna 112a. The method 600 may involve, at 630, combining an in-phase component of the reference signal to the first signal 104a to form a first alpha signal 590. The method 600 may involve, at 640, combining a quadrature component of the first reference signal to the first signal 104a to form a first beta signal 592. The method 600 may involve, at 650, receiving a second signal 104b at a second antenna 112b. The method 600 may involve, at 660, combining an in-phase component of the reference signal to the second signal 104b to form a second alpha signal 594. The method 600 may involve, at 670, combining a quadrature component of the second reference signal to the second signal 104b to form a second beta signal 596. The method 600 may involve, at 680, determining a first angle of arrival based on the first alpha signal 590, the first beta signal 592, the second alpha signal 594, and the second beta signal 596. It is noted that the received signals (e.g., the first and second signals 104a, 104b) may be radio frequency (RF) signals or the like.

[0040] FIG. 6B show further optional operations or aspects of the method 600 described above with reference to FIG. 6A. If the method 600 includes at least one block of FIGS. 6 A, then the method 600 may terminate after the at least one block, without necessarily having to include any subsequent downstream block(s) that may be illustrated. It is further noted that numbers of the blocks do not imply a particular order in which the blocks may be performed according to the method 600.

[0041] The method 600 may involve, at 682, receiving a third signal at a third antenna 112c. The method 600 may involve, at 684, combining an in-phase component of the reference signal to the third signal to form a third alpha signal 590. The method 600 may involve, at 686, combining a quadrature component of the third reference signal to the third signal to form a third beta signal 592. The method 600 may involve, at 688, receiving a fourth signal at a fourth antenna 112b. The method 600 may involve, at 690, combining an in-phase component of the reference signal to the fourth signal to form a fourth alpha signal 594. The method 600 may involve, at 692, combining a quadrature component of the fourth reference signal to the fourth signal to form a fourth beta signal 596. The method 600 may involve, at 694, determining a second angle of arrival based on the third alpha signal 590, the third beta signal 592, the fourth alpha signal 594, and the fourth beta signal 596.

[0042] In accordance with one or more aspects of the embodiments described herein, FIG. 7A shows a design of an apparatus 700 for determining a user device location. The exemplary apparatus 700 may be configured as a computing device or as a processor or similar device/component for use within. In one example, the apparatus 700 may include functional blocks that can represent functions implemented by a processor, software, or combination thereof (e.g., firmware). In another example, the apparatus 300 may be a system on a chip (SoC) or similar integrated circuit (IC).

[0043] In one embodiment, apparatus 700 may include an electrical component or module 710 for generating a reference signal. For example, the component 710 may include the local oscillator 550 as shown in FIG. 5.

[0044] The apparatus 700 may include an electrical component 720 for receiving a first signal at a first antenna. For example, the component 720 may include the antenna 112a receiving a device signal 104a as shown in FIG. 3.

[0045] The apparatus 700 may include an electrical component 730 for combining an in-phase component of the reference signal to the first signal to form a first alpha signal. For example, the component 730 may include the signal mixer 570 as shown in FIG. 5.

[0046] The apparatus 700 may include an electrical component 740 for combining a quadrature component of the reference signal to the first signal to form a first beta signal. For example, the component 740 may include the signal mixer 570 as shown in FIG. 5.

[0047] The apparatus 700 may include an electrical component 750 for receiving a second signal at a second antenna. For example, the component 750 may include the antenna 112b receiving a device signal 104b as shown in FIG. 3.

[0048] The apparatus 700 may include an electrical component 760 for combining the in-phase component of the reference signal to the second signal to form a second alpha signal. For example, the component 760 may include the signal mixer 570 as shown in FIG. 5.

[0049] The apparatus 700 may include an electrical component 770 for combining a quadrature component of the reference signal to the second signal to form a second beta signal. For example, the component 770 may include the signal mixer 570 as shown in FIG. 5.

[0050] The apparatus 700 may include an electrical component 780 for determining a first angle of arrival based on the first alpha signal, the first beta signal, the second alpha signal, and the second beta signal. For example, the component 780 may include the digital processor 440 as shown in FIG. 5.

[0051] FIG. 7B shows further optional aspects of the apparatus of FIG. 7A. In related aspects, as described in FIG. 7B, the apparatus 700 may include an electrical component 782 for receiving a third signal at a third antenna. For example, the component 782 may include the antenna 112c as shown in FIG. 5.

[0052] The apparatus 700 may optionally include an electrical component 784 for combining an in-phase component of the reference signal to the third signal to form a third alpha signal. For example, the component 784 may include the signal mixer 570 as shown in FIG. 5.

[0053] The apparatus 700 may include an electrical component 786 for combining a quadrature component of the reference signal to the third signal to form a third beta signal. For example, the component 786 may include the signal mixer 570 as shown in FIG. 5.

[0054] The apparatus 700 may include an electrical component 788 for receiving a fourth signal at a fourth antenna. For example, the component 788 may include the antenna 112d as shown in FIG. 5.

[0055] The apparatus 700 may include an electrical component 790 for combining the in-phase component of the reference signal to the fourth signal to form a fourth alpha signal. For example, the component 790 may include the signal mixer 570 as shown in FIG. 5.

[0056] The apparatus 700 may include an electrical component 792 for combining a quadrature component of the reference signal to the fourth signal to form a fourth beta signal. For example, the component 792 may include the signal mixer 570 as shown in FIG. 5. [0057] The apparatus 700 may include an electrical component 794 for determining a second angle of arrival based on the third alpha signal, the third beta signal, the fourth alpha signal, and the fourth beta signal. For example, the component 794 may include the digital processor 440 as shown in FIG. 5.

[0058] In further related aspects, the apparatus 700 may optionally include a processor component 702. The processor 702 may be in operative communication with the components 710-794 via a bus 701 or similar communication coupling. The processor 702 may effect initiation and scheduling of the processes or functions performed by electrical components 710-794.

[0059] In yet further related aspects, the apparatus 700 may include a radio transceiver component 703. A standalone receiver and/or standalone transmitter may be used in lieu of or in conjunction with the transceiver 703. The apparatus 700 may also include a network interface 705 for connecting to one or more other communication devices or the like. The apparatus 700 may optionally include a component for storing information, such as, for example, a memory device/component 704. The computer readable medium or the memory component 704 may be operatively coupled to the other components of the apparatus 700 via the bus 701 or the like. The memory component 704 may be adapted to store computer readable instructions and data for effecting the processes and behavior of the components 710-794, and subcomponents thereof, or the processor 702, or the methods disclosed herein. The memory component 704 may retain instructions for executing functions associated with the components 710-794. While shown as being external to the memory 404, it is to be understood that the components 710-394 can exist within the memory 704. It is further noted that the components in FIGS. 7A and 7B may comprise processors, electronic devices, hardware devices, electronic sub-components, logical circuits, memories, software codes, firmware codes, etc., or any combination thereof.

[0060] Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof. [0061] Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the disclosure herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.

[0062] The various illustrative logical blocks, modules, and circuits described in connection with the disclosure herein may be implemented or performed with a general- purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general- purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0063] The steps of a method or algorithm described in connection with the disclosure herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal. [0064] In one or more exemplary designs, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a non-transitory computer-readable medium. Non- transitory computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and blue ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of non-transitory computer-readable media.

[0065] The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

CLAIMS WHAT IS CLAIMED IS:

1. A method for determining a location of a user device, the method comprising: generating a reference signal;

receiving a first signal at a first antenna;

combining an in-phase component of the reference signal to the first signal to form a first alpha signal;

combining a quadrature component of the reference signal to the first signal to form a first beta signal;

receiving a second signal at a second antenna;

combining the in-phase component of the reference signal to the second signal to form a second alpha signal;

combining the quadrature component of the reference signal to the second signal to form a second beta signal; and

determining a first angle of arrival based on the first alpha signal, the first beta signal, the second alpha signal, and the second beta signal.

2. The method of claim 1, wherein the first signal and the second signal are transmitted by a single user device.

3. The method of claim 1, wherein the first signal is substantially equal to the second signal with a phase shift.

4. The method of claim 1, wherein the first antenna and the second antenna are separated by a first antenna distance substantially equal to an integer multiple of half a wavelength of the first signal.

5. The method of claim 1, wherein the first signal has a first signal identification and the second signal has a second signal identification identical to the first signal identification.

6. The method of claim 5, wherein the first signal identification comprises a MAC address.

7. The method of claim 1, additionally comprising:

receiving at a third antenna, a third signal;

combining the in-phase component of the reference signal to the third signal to form a third alpha signal; combining the quadrature component of the reference signal to the third signal to form a third beta signal;

receiving at a fourth antenna, a fourth signal;

combining the in-phase component of the reference signal to the fourth signal to form a fourth alpha signal;

combining the quadrature component of the reference signal to the fourth signal to form a fourth beta signal;

determining a second angle of arrival based on the third alpha signal, the third beta signal, the fourth alpha signal, and the fourth beta signal.

8. The method of claim 7, wherein a first line between the first antenna and the second antenna is substantially perpendicular to a second line between the third antenna and the fourth antenna.

9. The method of claim 7, additionally comprising determining a possible user device location based on the first angle of arrival and the second angle of arrival.

10. The method of claim 7, wherein the first antenna, the second antenna, the third antenna, and the fourth antenna are coupled to a ceiling of an indoor facility.

11. The method of claim 7, additionally comprising determining a user device location based on the first angle of arrival, the second angle of arrival, a ceiling height, and an assumed user device height.

12. The method of claim 1, wherein the user device comprises a smartphone, laptop, tablet, or portable computing device.

13. The method of claim 1, wherein the first signal and the second signal are within an ISM band.

14. The method of claim 1, wherein the first signal and second signal are Wi-Fi (IEEE 802.i l) signals.

15. The method of claim 1, wherein the first signal and second signal are Bluetooth signals.

16. The method of claim 1, wherein the user device comprises a RFID tag.

17. An apparatus, comprising:

a receiver configured to:

receive a first signal at a first antenna; and

receive a second signal at a second antenna; and

a processor configured to: generate a reference signal;

combine an in-phase component of the reference signal to the first signal to form a first alpha signal;

combine a quadrature component of the reference signal to the first signal to form a first beta signal;

combine an in-phase component of the reference signal to the second signal to form a second alpha signal;

combine a quadrature component of the reference signal to the second signal to form a second beta signal; and

determine a first angle of arrival based on the first alpha signal, the first beta signal, the second alpha signal, and the second beta signal.

18. The apparatus of claim 17, wherein the first signal and the second signal are transmitted by a single user device.

19. An apparatus, comprising:

means for generating a reference signal;

means for receiving a first signal at a first antenna;

means for combining an in-phase component of the reference signal to the first signal to form a first alpha signal;

means for combining a quadrature component of the reference signal to the first signal to form a first beta signal;

means for receiving a second signal at a second antenna;

means for combining an in-phase component of the reference signal to the

second signal to form a second alpha signal;

means for combining a quadrature component of the reference signal to the

second signal to form a second beta signal; and

means for determining a first angle of arrival based on the first alpha signal, the first beta signal, the second alpha signal, and the second beta signal.

20. A computer program product, comprising:

a computer-readable medium comprising code for causing at least one computer to:

generate a reference signal;

receive a first signal at a first antenna; combine an in-phase component of the reference signal to the first signal to form a first alpha signal;

receive a second signal at a second antenna;