Method and apparatus for acquiring an initial position for a stationary vehicle using a radio signal receiver

Abstract

A method and apparatus for computing an accurate position of a mobile device and transmitting the accurate position to a radio signal receiver located in a stationary vehicle to facilitate initialization of the radio signal receiver.

Description

METHOD AND APPARATUS FOR ACQUIRING AN INITIAL POSITION FOR A STATIONARY VEHICLE USING A RADIO SIGNAL RECEIVERBACKGROUNDField

[0001] Embodiments of the present invention generally relate to radio signal receivers and, in particular, to a method and apparatus for acquiring an initial position for a stationary vehicle using a radio signal receiver.Description of the Related Art

[0002] Positioning signal receivers such as receivers for global satellite navigation systems (GNSS) signals are used in the operation of autonomous vehicles and vehicles with self-driving modes to determine the location of the vehicle. A GNSS receiver (e.g., receivers for GPS, GLONASS, GALILEO, BEIDOU, etc. satellite signals or a combination thereof) receive signals from satellites, process the received signals and determine the position of the receiver from information contained in the received signals. The typical accuracy of a consumer receiver without the assistance of an inertial measurement unit (IMU) can range from 5 to 50m. To provide inertial navigation in an autonomous vehicle, an IMU typically comprises a magnetometer, a gyroscope and an accelerometer, i.e. , traditional IMU sensors. The signals from these three sensors (typically, MEMS-based sensors) are used to augment the GNSS receiver’s positioning computation such that the receiver accuracy may be improved to about 20cm and enable the vehicle's orientation to be known and tracked.

[0003] When an autonomous vehicle is deactivated (e.g., parked), the various sensors and receivers are also deactivated. Upon reactivation, the vehicle cannot operate autonomously or in a self-driving mode until the GNSS receiver reacquires the GNSS satellite signals and determines the pose (position and orientation) of the vehicle. The result is a delay in the start of autonomous or self-driving modes. In the worst case, the autonomous vehicle may not be able to acquire weak GNSS signals and may never move unless driven in manual mode. This problem is especially acute when autonomous vehicles and / or vehicles with self-driving modes are parked in parking decks or in an urban canyon where GNSS signals are readily attenuated, reflected, or blocked.

[0004] Therefore, there is a need for a method and apparatus for acquiring an accurate position and / or orientation of a vehicle using advanced signal processing techniques within a radio signal receiver.SUMMARY

[0005] Embodiments of the present invention generally relate to a method and apparatus for acquiring an initial position for a stationary vehicle using a radio signal receiver as shown in and / or described in connection with at least one of the figures.

[0006] Various features and advantages of the present disclosure may be appreciated from a review of the following detailed description of the present disclosure, along with the accompanying figures in which like reference numerals refer to like parts throughout.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] So that the manner in which the features of the present invention can be understood in detail, a particular description of the invention, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

[0008] FIG. 1 depicts a scenario for use of an acquisition method to acquire an initial position for a vehicle using a radio signal receiver in accordance with at least one embodiment of the invention;

[0009] FIG. 2 is a functional block diagram of a radio signal receiver in accordance with at least one embodiment of the invention;

[0010] FIG. 3 is a block diagram of a computing device used to perform some of the functions of the receiver of FIG. 2 in accordance with at least one embodiment of the invention;

[0011] FIG. 4 is a flow diagram of a method of operating the receiver to perform signal acquisition in accordance with at least one embodiment of the invention; and

[0012] FIG. 5 is a flow diagram of a method of operating a receiver in a stationary vehicle to perform signal acquisition in accordance with at least one embodiment of the invention.DETAILED DESCRIPTION

[0013] Embodiments of the present invention comprise apparatus and methods for acquiring an initial position for a stationary vehicle using a radio signal receiver that uses motion compensated signal processing in challenging signal environments. Such receivers include positioning systems (e.g., a GNSS receiver) and / or communications receivers (e.g., WiFi, cellular, Bluetooth communications receivers).

[0014] In various embodiments, a position is determined within a mobile radio receiver carried by a mobile platform (e.g., a person) nearby the stationary vehicle. The mobile receiver’s position is transferred to a radio receiver within the vehicle and used by the vehicle’s receiver as the vehicle’s initial position. In some embodiments, as described below, additional information may be transferred from the mobile device to the vehicle. Such information may be any information that is useful in receiver initialization assistance, i.e., initialization assistance information, such as, but not limited to position, time, satellite orbits (ephemeris), visible satellites, high elevation satellites, atmospheric delay information, and the like.

[0015] The mobile radio receiver utilizes motion compensated signal processing (also referred to as motion compensated correlation) to facilitate receiving signals and determining position in challenging signal environments (e.g., high multipath environments, attenuated signal environments and / or the like). Through the use of motion compensated signal processing, the mobile receiver processes the received signals using a long integration period to improve signal reception. Consequently, the vehicle’s receiver receives an initial position produced with enhanced signal processing achieved through motion compensated signal processing.

[0016] Satellite-based positioning systems and communications receivers utilize encoded digital signals including a deterministic digital code to facilitate signal acquisition, e.g., Gold codes. Such a digital code is determined by the mobile receiver and repeatedly broadcast by the transmitter to enable receivers to acquire and process transmitted signals. Using such deterministic codes combined with anaccurate motion estimation of the receiver antenna, embodiments of the invention are useful to enable a receiver to improve its position computation accuracy and / or signal reception. The technique for improving radio signal reception using antenna motion compensated signal processing is known as SUPERCORRELATION™ and is described in commonly assigned US patent 9,780,829, issued 3 October 2017; US patent 10,321,430, issued 11 June 2019; US patent 10,816,672, issued 27 October 2020; US patent publication 2020 / 0264317, published 20 August 2020; US patent publication 2020 / 0319347, published 8 October 2020, and US Patent Publication No. US20240014549A1, published 11 January 2024, which are hereby incorporated herein by reference in their entireties. A GNSS receiver that uses the SUPERCORRELATION™ technique is referred to as an S-GNSS® receiver. SUPERCORRELATION™ and S-GNSS® are trademarks of Focal Point Positioning Ltd. For the SUPERCORRELATION™ technique to function properly, the receiver antenna must be moving relative to the transmitter as the transmitted signals are being received.

[0017] In an embodiment of the invention, the receiver antenna is mounted to a mobile user device such as, but not limited to, smartphone, tablet, stand-alone GNSS receiver, or other mobile device containing a radio signal receiver capable of performing SUPERCORRELATION™ processing. The mobile user device is moved as a mobile platform (e.g., person) carrying the device moves. For accurate results, the antenna movement should be through a distance of at least a quarter to a half wavelength or more of the received signal, e.g., for GNSS signals - the wavelength ranges from 19 cm to 25 cm depending on the system and signal frequency used by the system.

[0018] Upon receiving radio signals from the moving antenna, the mobile radio signal receiver uses motion compensated signal processing (known as SUPERCORRELATION™ processing) to select the “best” GNSS signals to use for position determination and navigation. The “best” signals are typically line-of-sight (LOS) or direct signals from the transmitter (e.g., GNSS satellite), while reflected, non-line-of-sight (NLOS) signals and / or severely attenuated signals are rejected for use in the position computation. The SUPERCORRELATION™ processing is capable of discriminating between the angle-of-arrival of received signals, for example, betweenthe direct LOS signal and the reflected NLOS signals which arrive at the receiver antenna from different directions. The SUPERCORRELATION™ processing is also capable of differentiating between legitimate GNSS signals from GNSS satellites and spoofing GNSS signals sent from unauthorized transmitters. The selected signals are coupled to a navigation engine to rapidly and accurately determine the mobile receiver position. In this manner, reflected signals and highly attenuated signals (as well as spoofer signals) are rejected and not used in the navigation solution.

[0019] As the mobile receiver nears a stationary vehicle that is incapable of performing SUPERCORRELATION™ because of its lack of motion, the mobile receiver transfers its position (and any other initialization assistance information) to the vehicle’s receiver. Such transmission is generally via a short-range transmission protocol. Any such protocol may be used - for example, BLUETOOTH or WiFi communications may be used. Note that the mobile device may merely be passing by the vehicle (i.e. , the platform carrying the mobile device may not be associated with the vehicle). In other embodiments, for added security, the transmission of the position may occur only when the mobile device enters (or is near) the vehicle and pairs with the vehicle’s phone or infotainment system.

[0020] In an embodiment, the vehicle’s radio receiver is embedded in, attached to or carried by, a moving platform such as, for example, but not limited to, an automobile, motorcycle, airplane, helicopter, drone, bicycle, and the like. In its broadest sense, embodiments of the invention find use in any vehicle, but such embodiments are most useful when used by an autonomous vehicle, a vehicle that uses a self-driving mode, or any vehicle that requires knowledge of its initial position-especially within a challenging signal environment such as, but not limited to, urban canyons, under dense foliage, proximate one or more spoofers, in a parking garage, and the like.

[0021] The technical effect of this invention is to provide a vehicle an initial position when an initial position cannot be accurately determined by the vehicle’s receiver, e.g., the vehicle is located in a challenging signal environment. By using a position determined by a nearby mobile receiver, where the mobile receiver utilizes motion compensated correlation (e.g., a SUPERCORRELATION™ technique) to produce an accurate position in a challenging signaling environment. Consequently, a vehicle thatwould otherwise not be able to operate in autonomous or self-driving mode due to a lack of knowledge of its initial position is now capable of initializing.

[0022] Various embodiments receive and utilize GNSS signals from one or more of the available GNSS, e.g., GPS, GLONASS, GALILEO, BEIDOU, etc. The mobile receiver may be multi-band and receive and process signals from a plurality of different GNSSs. Although this disclosure focuses on the determining position from GNSS signals, embodiments may also use WiFi, BLUETOOTH, cellular signals, and the like to determine position using the SUPERCORRELATION™ technique.

[0023] FIG. 1 depicts a scenario 100 that uses a radio receiver 130 in a mobile device 128 to determine a position of the mobile device 128 and, when the mobile device 128 is proximate a vehicle 102 requiring an initial position, the mobile device 128 transmits its position to a radio signal receiver 104 in the vehicle 102 in accordance with at least one embodiment of the invention. In scenario 100, a stationary vehicle 102 that requires accurate initial knowledge of its position (i.e. , less than approximately 5-10 meters of error) carrying a receiver 104 (position A) is parked within a building 106 (e.g., a car park or garage). While within the building 106, the receiver 104 does not have a clear view of the sky and the satellite signals 110, 114, and 126 broadcast from a plurality of satellites 108-1, 108-2, . . . 108-N are severely attenuated, are subject to multipath interference, and may be reflected (signal 126). The radio receiver may be in a ‘multi-path’ environment, comprising a complex mix of signals reflected or refracted from the myriad of structures around it, as well as the signals received directly along the line-of-sight path from the transmitter to the receiver. Consequently, upon activation, the receiver 104 may not be able to accurately determine its initial position.

[0024] The mobile device 128 is in motion (arrow 136), e.g., carried by a moving platform such as a person 132 or another vehicle (not shown). The radio signal receiver 130 within the mobile device 128 uses motion compensated correlation (the SUPERCORRELATION™ technique) to process at least one received signal (e.g., one or more of GNSS signals 110, 112, 126) and determine a position in a challenging signal environment, such as being located in a parking structure 106 of scenario 100. If the receiver 130 has had a previous position fix, a position update may be performed using as few as a single received signal from a single satellite. As such, embodimentsof the invention may produce a receiver position based on at least one received signal. The mobile device’s position is transmitted along path 134 to the vehicle 102 to be used by the vehicle’s radio signal receiver 104 as an initial position. In one embodiment, the mobile device 128 may use an embodiment of the motion compensated correlation signal processing technique, as described below, to quickly determine the mobile device’s accurate position. The vehicle’s receiver 104 may be a standard GNSS receiver or may be a GNSS receiver that uses the SUPERCORRELATION™ technique.

[0025] The vehicle’s receiver 104 is capable of receiving the initial position from the mobile device 128. In some embodiments, the mobile device 128 may transfer more information than only the position, such as, but not limited to, satellite information (e.g., which satellite signals are line-of-sight signals), timing information, atmospheric delay information, GNSS satellite orbit information, and the like.

[0026] In another situation (position B), the stationary vehicle 102 may be parked in an urban canyon (surrounded by tall buildings 106 and 122) and, when the vehicle is activated, the receiver 104 receives direct signals 112 and 116, reflected signals 120 and some signals 118 are blocked or severely attenuated. Using such indirect (reflected) signals in a navigation solution results in a very inaccurate solution and, in some cases, the reflected signals may result in multipath interference so severe, a position cannot be computed. The mobile device 128 transmits its position via path 138 to the vehicle 102 to be used as the vehicle’s initial position. An embodiment of the motion compensated correlation signal processing technique is used, as described below, to quickly determine the mobile device’s accurate position.

[0027] FIG. 2 is a functional block diagram of the mobile device’s radio signal receiver 130 and the vehicle’s radio signal receiver 104 of FIG. 1 in accordance with at least one embodiment of the invention. In one exemplary embodiment, the receiver 130 comprises an antenna 202, a front end 204, a GNSS signal processor and navigation engine 206, motion compensation processor 208, a transceiver 218, a transceiver antenna 220, and a motion module 212. These components form an S-GNSS receiver capable of transmitting its determined position in accordance with at least one embodiment of the invention.

[0028] The motion compensation processor 208 comprises a trigger module 214 and the motion module 210 may comprise an inertial measurement unit (IMU) 212. The IMU 212 comprises one or more sensors such as, but not limited to an accelerometer, a gyroscope, a magnetometer, a barometer, and the like. In some embodiments, an IMU is not necessary.

[0029] The receiver’s front end 204 downconverts, filters, and samples (digitizes) the at least one received signal in a manner that is well-known to those skilled in the art. The output of the receiver front end 204 is a digital signal containing data. The data of interest for performing motion compensation is a deterministic code, e.g., Gold code, used by the GNSS signal processor 206 to synchronize the receiver 104 to the GNSS transmission and acquire the at least one GNSS signal.

[0030] During GNSS signal acquisition, the GNSS signal processor 206 correlates the received code from each satellite with locally generated codes to produce correlation results. The correlation results are processed by the navigation engine 206 as is well-known in the art to generate position information, e.g., the correlation results are used to determine pseudoranges to each satellite and the pseudoranges are processed to compute the receiver position. The motion compensation processor 208 performs the SUPERCORRELATION™ processing to provide signals (phasor sequences) to phase adjust the correlation results such that the coherent integration period is extended, e.g., extended to one or more seconds, such that very attenuated signals may be received and used for navigation. The phasor sequence is a time sequence of phase offsets where each phasor in the sequence adjusts the phase of a signal sample. The adjustment may be performed by adjusting the phase of each complex sample of the received signals, the locally generated signals or the correlation results themselves. The least computationally intensive adjustment process adjusts the phase of the correlation results.

[0031] The motion module 210 generates receiver motion information that is used by the motion compensation processor 208 to generate phasor sequences that are used to motion compensate the correlation results. The phasor sequences comprise a sequence of phase offsets to be made over time, e.g., across a received signal, to compensate for phase changes that occur over time due to movement of the receiver. In one embodiment, the motion module 210 uses a known model of antenna motion(e.g., a known model of the motion of the vehicle component on which the antenna is mounted) and / or an IMU 212 to generate motion information for the motion compensation processor 208. In one embodiment, motion information may comprise a prediction of antenna motion. In one alternative embodiment, the motion module 210 may comprise an IMU 212 to provide vehicle orientation information and / or measurements of the vehicle component motion (e.g. the motion of a door being opened and / or closed) which may optionally be combined with a motion model to generate accurate antenna motion information. The motion compensation processor 208 provides motion estimation correction information along path 216 to the motion module 210. In this manner, the motion compensation processor 208 provides corrective feedback to the motion module 210.

[0032] The trigger module 214 may be an element of the motion compensation processor 208. In one embodiment, the trigger module 214 is activated when the stationary vehicle receiver 104 is proximate the mobile device receiver 128 (e.g., detecting the proximity of the mobile device 130 to the vehicle 102 via a person unlocking the vehicle door. When this occurs, the transceiver 218 transmits a signal 230 via antenna 220. The signal carries the determined position of the receiver 130. Optionally, additional information may be transmitted, such as, but not limited to, satellite information (e.g., which satellite signals are line-of-sight signals), timing information, atmospheric delay information, GNSS satellite orbit information, and the like. Such information is referred to as initialization assistance information and may generally contain the position as well as any other information known to the mobile device or its receiver that is useful to initialize a GNSS or S-GNSS receiver.

[0033] The vehicle receiver 104 comprises a short-range signal antenna 222, a transceiver 224, a GNSS or S-GNSS receiver 226 and a GNSS antenna 228. The GNSS receiver operates as is well known in the art to receive GNSS satellite signals and determine the vehicle’s position. If the vehicle receiver 104 is an S-GNSS receiver, it will operate as described above with respect to the mobile device’s receiver. Upon initializing in a challenging signal environment, the GNSS receiver cannot determine its position in view of either high multipath conditions or highly attenuated signals (or possibly, interreference from other radio sources). As such, aninitial position is needed for the receiver 104 to determine the available satellites and their signals.

[0034] The short-range signal antenna receives the position signal 230 and the transceiver 224 to which the antenna 222 is connected processes the received signal 230 to extract the initialization assistance information that may be used to initialize the receiver 104.

[0035] Activation that leads to transmission of the initialization assistance information may be detected by, one or more of, the approach of a person carrying a key fob for the vehicle, a door being unlocked, a door handle being manipulated, an activation signal being transmitted from a remote location (e.g., an auto-start signal or an autonomous vehicle activation command), the ‘start’ button of the vehicle being operated, and the like. Any such activation indicates a need for a vehicle position to be transmitted. Once a need for a position is detected, the vehicle transceiver 224 communicates a request for information to the mobile device transceiver 218. The transceiver 224 may be a component of the vehicle’s infotainment system, i.e., a BLUETOOTH transceiver that is paired to the mobile device 128.

[0036] FIG. 3 is a block diagram of a computing device 350 programmed to perform the functions of the GNSS processor and navigation engine 206 and the motion compensation processor 208 within the receiver 130 of FIGs. 1 and 2 in accordance with at least one embodiment of the invention. The computing device 350 comprises at least one processor 300, support circuits 302 and memory 304. The at least one processor 300 may be any form of processor or combination of processors including, but not limited to, central processing units, microprocessors, microcontrollers, field programmable gate arrays, graphics processing units, digital signal processors, and the like. The support circuits 302 may comprise well-known circuits and devices facilitating functionality of the processor(s). The support circuits 302 may comprise one or more of, or a combination of, power supplies, clock circuits, analog to digital converters, communications circuits, cache, displays, and / or the like.

[0037] The memory 304 comprises one or more forms of non-transitory computer readable media including one or more of, or any combination of, read-only memory or random-access memory. The memory 304 stores software and data including, forexample, acquisition software 306, SUPERCORRELATION™ software 308, navigation software 310 and data 312. The data 312 satellite information 314, motion information, and various additional data used to perform the acquisition processing.

[0038] During normal operation, the processor 300 executes the SUPERCORRELATION™ software 308 to select and motion compensate GNSS signals to be processed by the navigation software 310. The selected GNSS signals are selected because they are expected to rapidly be processed by the navigation software into an accurate vehicle position. When the acquisition software 306 detects a request for initialization assistance information, the acquisition software 306 causes the transceiver (218 of FIG. 2) to transmit the information to the vehicle. In some embodiments, the acquisition software 306 may initiate bi-directional communication between the mobile device and vehicle to enhance security and ensure the mobile device is a known device, e.g., via BLUETOOTH pairing or other secure short-range communication.

[0039] FIG. 4 is a flow diagram of a method 400 of operation of the receiver in accordance with at least one embodiment of the invention. The method 400 may be implemented in software, hardware or a combination of both (e.g., using the GNSS processor and navigation engine 206, the motion compensation processor 208 and the trigger module 214 of FIG. 2).

[0040] The method 400 is activated and begins at 402 when a need for a position is detected, e.g., when a person carrying the vehicle’s key fob approaches the vehicle, when a driver unlocks and / or opens a driver’s door, when a signal is sent to the vehicle to begin initialization, and the like. The method 400 proceeds to 404 where the antenna receives at least one signal from at least one remote source (e.g., transmitters such as the GNSS satellites 108 of FIG. 1) in a manner as described with respect to FIG. 1. At 406, the at least one received signal is buffered in memory. Each received signal comprises a synchronization or acquisition code, e.g., a Gold code, extracted from the radio frequency (RF) signal received at the antenna. The process of downconverting the RF signal and sampling the digital code is well known in the art. The buffered signals may be representations of the received signals such as, but not limited to, digitized RF signals, digitized, downconverted signals, baseband signals, extracted code, correlation results and the like.

[0041] At 408, the GNSS processor acquires the at least one GNSS signal using a traditional signal acquisition procedure. The GNSS processor acquires as many signals as it is able to acquire and produces an initial receiver position and time (typically accurate to within about 1km and within seconds of the actual time). These signals may include severely attenuated, reflected signals and direct signals resulting in an inaccurate position and time. In some embodiments the GNSS processor may make use of externally provided data, such as local time, approximate location (e.g. from local cellular tower) and satellite ephemeris data in order to target acquisition of signals from satellites that are currently above the local horizon.

[0042] At 410, the method 400 initiates the SUPERCORRELATION™ processing to process the received GNSS signals. The signals are processed using motion compensated correlation as described in commonly assigned US patent 9,780,829, issued 3 October 2017; US patent 10,321,430, issued 11 June 2019; US patent 10,816,672, issued 27 October 2020; US patent publication 2020 / 0264317, published 20 August 2020; US patent publication 2020 / 0319347, published 8 October 2020, and US Patent Publication No. US20240014549A1 , published 11 January 2024, which are hereby incorporated herein by reference in their entireties.

[0043] Specifically, the method 400 performs SUPERCORRELATION™ using motion hypotheses and the received signal(s). During this process, the SUPERCORRELATION™ procedure generates a plurality of phasor sequence hypotheses related to the motion information. These hypotheses comprise a plurality of local signals representing code phase estimates. Each phasor sequence hypothesis comprises a phase estimate that varies with motion parameters of the receiver. The signal processing correlates a local code encoded in a local signal with a code encoded in the received RF signal. The phasor sequence hypotheses are used to adjust, at a sub-wavelength accuracy, the carrier phase of the local code. Such adjustment or compensation may be performed by adjusting a local oscillator signal, the received signal(s), or the correlation result. The signals and / or correlation results comprise complex signal samples having in-phase (I) and quadrature phase (Q) components. The method applies each phase offset in the phasor sequence to a corresponding complex sample in the signals and / or correlation results. For each received signal, the process correlates the received signals with a set (plurality) ofphasor sequence hypotheses containing estimates of a phase offset necessary to accurately correlate the received signals.

[0044] The motion estimates are typically hypotheses of a component of motion in a direction of interest such as in the direction of the satellite that transmitted the received signal, e.g., along the signal propagation path.

[0045] In one embodiment, if a signal from a given satellite was received previously, the set of hypotheses for the newly received signal include a group of phasor sequence hypotheses using the expected Doppler and Doppler rate and / or last Doppler and last Doppler rate used in receiving the prior signal from that particular satellite. The hypotheses values may be centered around the last values used or the last values used additionally offset by a prediction of further offset based on the expected receiver motion. The method 400 correlates each received signal with that signal’s set of hypotheses. The hypotheses are used as parameters to form the phase-compensated phasors to phase compensate the correlation process. As such, the phase compensation may be applied to the received signals, the local frequency source (e.g., an oscillator), or the correlation result values. The result of the correlation process is a plurality of phase-compensated correlation results - one phase-compensated correlation result value for each hypothesis for each received signal.

[0046] The method 400 processes the correlation results to find the “best” or optimal result for each received signal. In one embodiment, the method 400 produces a joint correlation output as a function (e.g., summation) of the plurality of correlation results resulting from all the hypotheses and received transmitter signals. The joint correlation output may be a single value or a plurality of values that represent the parameter hypotheses (preferred hypotheses) that provide an optimal or best correlation output. In general, a cost function is applied to each set of correlation values for each received signal to find the optimal correlation output corresponding to a preferred hypothesis or hypotheses.

[0047] For example, assuming all other receiver parameters are known except receiver motion direction, the method 400 tests hypotheses with various phasor sequences that compensate for phase changes due to each direction hypothesis. Thecorrect phasor sequence hypothesis that represents the accurate direction estimate will produce the highest correlation result magnitude for a given received signal. By processing the received signals from different satellites, the correlation results will converge upon hypotheses representing the true receiver motion direction.

[0048] In other embodiments, rather than using the largest magnitude correlation value as an indication of the correct hypothesis, other test criteria may be used. For example, the method 400 may monitor the progression of correlations as hypotheses are tested and apply a cost function that indicates the preferred hypotheses when the cost function reaches a minimum. As such, the joint correlation output may be a joint correlation value or a group of values.

[0049] As is known in the art, SUPERCORRELATION™ processing may be used to determine the direction of arrival of signals to facilitate identifying direct (or LOS) signals as compared to reflected (or NLOS) signals. In most cases, direct signals are better to use in a navigation solution and provide a more accurate position. Furthermore, SUPERCORRELATION™ processing enables extended coherent integration periods to be used on the GNSS signals resulting in an ability to receive and use very attenuated signals. This allows for GNSS signals that are received indoors to be used in the navigation solution.

[0050] Because the receiver knows the location of each GNSS satellite from the satellite ephemeris information, an anomalous direction from which a signal is received is an indication that the signal is a NLOS signal or a spoofer. These signals can then be rejected for use in the navigation solution.

[0051] At 412, the method 400 queries whether the correlation results represent signals that are sufficient to produce an accurate position solution. If the method 400 determines that none or not enough of the received signals are of sufficient quality to compute an accurate position solution, the method 400 returns, along path 422, to 404 to receive additional GNSS signals while moving the antenna. In one embodiment, sufficient quality may be measured by the number of direct satellite signals that are available, e.g., if very few direct signals are available, the navigation solution would be inaccurate. In other embodiments, the GNSS processor may produce a sufficiency score in a standard manner based on signal noise, error ellipse,signal strength, frequency error, code phase error, etc. In another embodiment, the period during which GNSS signals are received at the moving antenna and coherently integrated using SUPERCORRELATION™ processing may be dynamically increased in order to boost further the signal-to-noise ratio of the line-of-sight signals. This is of particular importance where the line-of-sight signals are heavily attenuated, for example when the mobile device is positioned in a covered car park or parking garage. If the correlation results are sufficient, the method 400 continues to 414.

[0052] At 414, the method 400 outputs the “best” or “preferred” signals to be used to calculate a receiver position. These signals are typically direct GNSS signals (i.e. , LOS signals) that have the highest signal-to-noise ratio. In this manner, reflected signals which contain unknown ranging errors are not used in the navigation solution and the accuracy of the position is substantially improved.

[0053] At 416, the selected compensated correlation results are used by a traditional navigation solution (e.g., using range to each satellite transmitter) to generate the position of the receiver.

[0054] At 418, once the mobile device position is determined, the initialization assistance information is transmitted to the vehicle. As mentioned above, the transmitted information includes at a minimum the mobile device position but may also include other information known to the mobile device that is useful in initializing the vehicle’s GNSS or S-GNSS receiver such as, but not limited to, satellite information (e.g., which satellite signals are line-of-sight signals), timing information, atmospheric delay information, and the like.

[0055] In some embodiments, the mobile device may not receive a request for the initialization assistance information before transmitting the information. In such embodiments, the mobile device may continuously share its position to assist any vehicle within communication range. In other embodiments, the mobile device and vehicle do not have to be paired such that one-to-one communication is pre-arranged for communications to occur. In such embodiments, the mobile device may continuously transmit a signal that identifies it as an S-GNSS receiver that is assistance enabled. The vehicle detects the proximity of such a receiver and requeststhe initialization assistance information - then, upon receiving the request, the mobile device responds with the information.

[0056] The method 400 ends at 420.

[0057] FIG. 5 is a flow diagram of a method 500 of operating a receiver in a stationary vehicle to perform signal acquisition in accordance with at least one embodiment of the invention. The method 500 begins at 502 and proceeds to 504 where the method waits to detect the mobile device (130 in FIG. 1). In one embodiment, the vehicle receiver 104 may detect the mobile device proximity through short range communications, or when a paired device is nearby as a person uses a key or fob to unlock or start the vehicle. In other embodiments, the receiver may not detect a proximate mobile device, the mobile device may continuously transmit initialization initiation information that is received by any receiver that is nearby. In still other embodiments, the vehicle may be a fully autonomous vehicle that is triggered from a remote operations center to begin requesting initialization initiation information from any S-GNSS enabled mobile device that is nearby.

[0058] In one embodiment, once the mobile device is detected, at 506, the method 500 requests the initialization initiation information. In response, the mobile device transfers the initialization initiation information to the vehicle receiver. At 508, the method 500 receives the initialization initiation information.

[0059] At 510, the initialization initiation information is used to initialize the receiver. At a minimum, the receiver now has an accurate position. In other embodiments, the receiver may additionally have received timing information, satellite position information, atmospheric delay information, and the like. All or some of this information is useful in enabling a standard GNSS receiver to begin operating in a challenging signal environment and, if the receiver is capable of S-GNSS processing using a SUPERCORRELATION™ technique, the receiver will produce highly accurate position information as soon as the vehicle begins moving, i.e. , the receiver will be ready for a hot start.

[0060] At 512, the vehicle is activated. Using the initialization initiation information, the vehicle may now operate in autonomous mode. At 514, the method 500 querieswhether the vehicle is moving. If the query is affirmatively answered (vehicle is moving and the receiver is S-GNSS enabled, the method proceeds to 516 to activate S-GNSS processing. Using S-GNSS processing enables the receiver to produce highly accurate positions for navigation even in a challenging signaling environment, e.g., high multipath, signal interference, signal attenuation and the like. If the vehicle is not moving or is not S-GNSS enabled, a standard GNSS receiver may use the initialization initiation information to improve its signal reception. As such, at 518, the method 500 activates a standard GNSS receiver. The method 500 ends at 520.

[0061] Here multiple examples have been given to illustrate various features and are not intended to be so limiting. Any one or more of the features may not be limited to the particular examples presented herein, regardless of any order, combination, or connections described. In fact, it should be understood that any combination of the features and / or elements described by way of example above are contemplated, including any variation or modification which is not enumerated, but capable of achieving the same. Unless otherwise stated, any one or more of the features may be combined in any order.

[0062] As above, figures are presented herein for illustrative purposes and are not meant to impose any structural limitations, unless otherwise specified. Various modifications to any of the structures shown in the figures are contemplated to be within the scope of the invention presented herein. The invention is not intended to be limited to any scope of claim language.

[0063] Where “coupling” or “connection” is used, unless otherwise specified, no limitation is implied that the coupling or connection be restricted to a physical coupling or connection and, instead, should be read to include communicative couplings, including wireless transmissions and protocols.

[0064] Any block, step, module, or otherwise described herein may represent one or more instructions which can be stored on a non-transitory computer readable media as software and / or performed by hardware. Any such block, module, step, or otherwise can be performed by various software and / or hardware combinations in a manner which may be automated, including the use of specialized hardware designed to achieve such a purpose. As above, any number of blocks, steps, or modules maybe performed in any order or not at all, including substantially simultaneously, i.e., within tolerances of the systems executing the block, step, or module.

[0065] Where conditional language is used, including, but not limited to, “can,” “could,” “may” or “might,” it should be understood that the associated features or elements are not required. As such, where conditional language is used, the elements and / or features should be understood as being optionally present in at least some examples, and not necessarily conditioned upon anything, unless otherwise specified.

[0066] Where lists are enumerated in the alternative or conjunctive (e.g., one or more of A, B, and / or C), unless stated otherwise, it is understood to include one or more of each element, including any one or more combinations of any number of the enumerated elements (e.g. A, AB, AC, ABC, ABB, etc.). When “and / or” is used, it should be understood that the elements may be joined in the alternative or conjunctive.

[0067] While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

Claims:

1. A method for transmitting an accurate position to a radio signal receiver located in a stationary vehicle comprising:receiving, at a moving antenna of a radio signal receiver located within a mobile device, at least one radio signal from at least one transmitter;determining motion of an antenna of the radio signal receiver; compensating a phase of an at least one of a local signal, the at least one received signals, or an at least one correlation result based on the determined motion to produce at least one motion compensated correlation result;selecting at least one specific received signal, based on the at least one motion compensated correlation result, for use in a navigation solution that determines a position of the mobile device; andtransmitting the position such that the position may be used to initialize the radio signal receiver located in the stationary vehicle.

2. The method of claim 1 , wherein the mobile device is a smartphone, tablet, or stand-alone GNSS receiver separate from the stationary vehicle.

3. The method of claim 1 , further comprising receiving, at the stationary vehicle, a signal to begin position initialization.

4. The method of claim 1 , wherein the at least one radio signal comprises a synchronization or acquisition code extracted from a radio frequency signal received at the antenna.

5. The method of claim 1 , wherein the at least one transmitter comprises at least one GNSS satellite.

6. The method of claim 1 , further comprising querying whether the at least one motion compensated correlation result represents at least one signal that is sufficient to produce an accurate position solution.

7. The method of claim 6, further comprising determining that the at least one motion compensated correlation result comprises a plurality of motion compensated correlation results that represent signals that are sufficient when a number of direct satellite signals that are available are greater than or equal to a predetermined threshold amount.

8. The method of claim 6, further comprising determining that the at least one motion compensated correlation result comprises a plurality of motion compensated correlation results that represent signals that are sufficient based on a sufficiency score based on at least one of signal noise, error ellipse, signal strength, frequency error, or code phase error.

9. The method of claim 1 , wherein the at least one specific received signal is at least one received signal that has the highest signal-to-noise ratio.

10. The method of claim 9, wherein the at least one specific received signal does not include a reflected signal.

11. An apparatus for transmitting an accurate position to a radio signal receiver located in a stationary vehicle, comprising at least one processor and at least one non-transient computer readable medium for storing instructions that, when executed by the at least one processor, causes the apparatus to perform operations comprising:receiving, at a moving antenna of a radio signal receiver located within a mobile device, at least one radio signal from at least one transmitter;determining motion of an antenna of the radio signal receiver;compensating a phase of an at least one of a local signal, the at least one received signals, or an at least one correlation result based on the determined motion to produce at least one motion compensated correlation result;selecting at least one specific received signal, based on the at least one motion compensated correlation result, for use in a navigation solution that determines a position of the mobile device; andtransmitting the position such that the position may be used to initialize the radio signal receiver located in the stationary vehicle.

12. The apparatus of claim 11 , wherein the mobile device is a smartphone, tablet, or stand-alone GNSS receiver separate from the stationary vehicle.

13. The apparatus of claim 11 , wherein the operations further comprise receiving, at the stationary vehicle, a signal to begin position initialization.

14. The apparatus of claim 11 , wherein the at least one radio signal comprises a synchronization or acquisition code extracted from a radio frequency signal received at the antenna.

15. The apparatus of claim 11 , wherein the at least one transmitter comprises at least one GNSS satellite.

16. The apparatus of claim 11 , wherein the operations further comprise querying whether the at least one motion compensated correlation result represents at least one signal that is sufficient to produce an accurate position solution.

17. The apparatus of claim 16, wherein the operations further comprise determining that the at least one motion compensated correlation result comprises a plurality of motion compensated correlation results that represent signals that are sufficient when a number of direct satellite signals that are available are greater than or equal to a predetermined threshold amount.

18. The apparatus of claim 16, wherein the operations further comprise determining that the at least one motion compensated correlation result comprises a plurality of motion compensated correlation results that represent signals that are sufficient based on a sufficiency score based on at least one of signal noise, error ellipse, signal strength, frequency error, or code phase error.

19. The apparatus of claim 11 , wherein the at least one specific received signal is at least one received signal that has the highest signal-to-noise ratio.

20. The apparatus of claim 19, wherein the at least one specific received signal does not include a reflected signal.

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