Method and apparatus for processing of radio signals in a parallel reflector environment

Abstract

A method and apparatus for processing radio signals while a receiver is traveling parallel to signal reflectors (e.g., buildings) is provided. In some embodiments, a method for performing signal processing in a radio signal receiver while the radio signal receiver is traveling through a parallel reflector environment, may include: receiving at least one radio signal from at least one transmitter; determining a motion of the radio signal receiver; performing, using the radio signal and the determined motion, motion compensated correlation in a direction of the at least one transmitter or a direction of a reflected signal to generate motion compensated correlation results; determining, from the motion compensated correlation results, a Doppler frequency of the at least one radio signal; adjusting at least one weighting of a navigation solution based upon the determined Doppler frequency; and executing the navigation solution.

Description

METHOD AND APPARATUS FOR PROCESSING OF RADIO SIGNALS IN A PARALLELREFLECTOR ENVIRONMENTBACKGROUNDField

[0001] Embodiments of the present invention generally relate to radio signal receivers and, in particular, to a method and apparatus for processing radio signals while a receiver is traveling parallel to signal reflectors (e.g., buildings).Description of the Related Art

[0002] Positioning signal receivers such as receivers for global satellite navigation systems (GNSS) signals have become ubiquitous in mobile devices and vehicles. 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 a typical mobile device, 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. However, that additional accuracy comes with a substantial cost of the IMU sensors and additional computational complexity.

[0003] In some instances, the receiver may be operating in an urban environment with only limited view of the sky such that buildings block, attenuate or reflect the GNSS signals. In such situations, a receiver may not be able to determine an accurate distance (i.e., pseudorange) between the receiver and the satellites. Consequently, the navigation solution may have to rely on a limited number of accurate pseudoranges related to satellite signals arriving directly from high elevation satellites or rely on inaccurate pseudoranges calculated from reflected signals. The result is generally an inaccurate position computation.

[0004] Therefore, there is a need in the art for a method and apparatus for signal processing of radio signals that are received in an urban environment.SUMMARY

[0005] Embodiments of the present invention generally relate to a method and apparatus for radio signal processing in a parallel reflector environment 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. 1A depicts a parallel reflector environment scenario where a radio signal receiver operates in the parallel reflector environment in accordance with at least one embodiment of the invention;

[0009] FIG. 1 B depicts a top view of the parallel reflector environment of FIG. 1 A;

[0010] FIG. 2 is a functional block diagram of a radio signal receiver in accordance with at least one embodiment of the invention;

[0011] FIG. 3 is a flow diagram of a method of performing signal processing of signals received in a parallel reflector environment in accordance with at least one embodiment of the invention; and

[0012] FIG. 4 depicts a vehicle transporting a receiver that is capable of performing motion compensated correlation to establish a cone of sensitivity for enhanced signal reception in accordance with at least one embodiment of the invention.DETAILED DESCRIPTION

[0013] Embodiments of the present invention comprise apparatus and methods of signal processing in a radio signal receiver that uses motion compensated signal processing. Such receivers include positioning systems (e.g., GNSS receivers).

[0014] Embodiments of the invention are intended to operate in urban canyons where the receiver is generally traveling along a street (e.g., in a vehicle) or sidewalk (e.g., carried by a person) where the buildings are oriented parallel to the direction of travel. In this scenario, the buildings form parallel signal reflectors and the environment is a parallel reflector environment. The receiver may know that it is operating in a parallel reflector environment through analysis of the received signals (e.g., signal strength analysis) and / or through use of a map, such as, but not limited to a three-dimensional map such as those used in three-dimensional mapping assisted (3DMA) positioning, two-dimensional digital maps, other forms of maps showing building locations and the like.

[0015] In one exemplary embodiment, the radio signal receiver temporarily stores or buffers data related to the received signals or partially processed received signals (collectively, referred to as a representation of the received signals). Such representations may include, but are not limited to, downconverted signals, sampled signals, filtered signals, correlation outputs and the like. In general, the data may be any data from which motion compensated correlation may be performed. The data also includes receiver antenna motion information.

[0016] The receiver uses a SUPERCORRELATION™ technique (i.e., motion compensated correlation) to process the buffered data using a very long integration period, e.g., about 1 second. Such a long integration period enables a very attenuated signal to be received and used to determine the receiver’s position. The longintegration period also enables the receiver to accurately discriminate an angle of arrival of signals such that signals may be received in an urban environment where the receiver is surrounded by buildings. Motion compensated correlation is performed through compensating for the component of the receiver motion that is in the direction of the transmitter. For a reflected signal, the direction of the transmitter is in the direction of the reflection point. In so doing, the direction of the transmitter lies along the edge of a cone of sensitivity whose axis is along the direction of motion of the receiver. The receiver performs such motion compensation on each signal received from each transmitter (e.g., GNSS satellites).

[0017] Satellite-based positioning systems 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 receiver and repeatedly broadcast by the transmitter to enable receivers to acquire and process transmitted signals. Using such deterministic codes combined with an accurate motion model of the receiver, 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 receiver motion compensated signal correlation 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 11 ,808,865, issued 7 November 2023; US patent 11 ,474,258, issued 18 October 2022; and US patent publication 2024 / 0045077, published 8 February 2024, which are hereby incorporated herein by reference in their entireties. The motion model is typically derived using inertial measurement unit (IMU) data; however, in embodiments of the invention, the motion model is derived using accelerometer data, gyroscope data, controller area network (CAN) bus data, visual odometry data, or a combination of data from any of these motion data sources.

[0018] In an embodiment, the GNSS receiver is embedded in or carried by a moving platform such as, for example, but not limited to, an automobile, motorcycle,airplane, helicopter, drone, bicycle, person (e.g., a person carrying a smartphone, tablet, computer, internet of things (loT) device, wearable device, etc.), and the like.

[0019] In operation, the at least one received signal is correlated with at least one locally generated signal to produce at least one correlation result. As is described in detail below, embodiments of the invention perform highly accurate receiver position determination using the Doppler frequency of at least one signal. The receiver, through the use of the SUPERCORRELATION™ technique, can be confident that the Doppler frequency that the receiver measures is accurate. A receiver that does not utilize the SUPERCORRELATION™ technique is subject to multipath interference that may impact the receiver’s ability to measure Doppler frequency and / or receive transmitter signals at all.

[0020] FIG. 1A and 1 B depict a scenario 100 in which a radio signal receiver performs signal processing using motion compensated signal correlation in a parallel reflector environment in accordance with at least one embodiment of the invention. FIG. 1A depicts the scenario 100 from a horizontal view parallel to the ground while FIG. 1 B depicts the scenario 100 from above perpendicular to the ground. In scenario 100, an automobile (vehicle) 104 carrying a GNSS receiver 106 moves along a street (arrow 110) between buildings 108A and 108B (i.e., forming a parallel reflector environment). The receiver 106 receives satellite signals 112 broadcast from a plurality of satellites 102A, 102B, and 102C. In such an environment, some signals will be received at the antenna 110 as direct signals 112A (also referred to as line of sight (LOS) signals), some signals will be attenuated (blocked) by buildings such as signal 112B, and some signals will be reflected before reaching the antenna 110 such as signals 112C.

[0021] The receiver 106 buffers (i.e., stores) data related to the received signals 112 or partially processed received signals (collectively, referred to as a representation of the received signals) as well as receiver antenna motion information (e.g., accelerometer and gyroscope measurements, CAN bus data, etc.). Such representations may include, but are not limited to, downconverted signals, sampledsignals, filtered signals, correlation outputs and the like. In general, the data may be any data from which motion compensated correlation may be performed.

[0022] The intent of using enhanced signal processing, such as the SUPERCORRELATION™ technique, is to produce a position accuracy equivalent to the position accuracy computed in an open sky scenario even when the receiver is in a complex environment, e.g., high multipath, electromagnetic interference and / or attenuated signal environments that occur in, for example, urban canyons, spoofing / jamming, and / or heavy foliage. As such, the position accuracy found in an open sky scenario is extended to other, more complex scenarios.

[0023] The receiver 106 may be a component (e.g., a GNSS receiver) within user equipment such as mobile phones, tablets, laptop computers, loT devices, wearable devices, and the like. For simplicity, the device is described herein as a receiver. Those skilled in the art will understand that the receiver may be a standalone receiver or may be a portion or component within user equipment.

[0024] The receiver 106 uses, for example, an omnidirectional antenna 110 (e.g., a planar monopole antenna) to continuously monitor its environment to receive positioning signals (e.g., GNSS signals). The receiver 106 processes the received signals to determine the receiver location. The receiver 106 determines its motion (path 110) and extracts a component of the motion that is in the direction of each transmitter (e.g., GNSS satellite) from which it is receiving signals.

[0025] By using motion compensated signal correlation, as depicted in FIG. 4, the receiver 106 establishes a cone of sensitivity 400 in the direction that maximizes signal reception for any signal 408 along the direction of the edge 402 of the cone of sensitivity 400. The edge 402 of the cone 400 defines an annulus 410 such that any signal propagating along the edge experiences enhanced signal processing gain. If the received signal is a LOS signal (e.g., from a satellite that is at a high elevation or known not to be obscured by a building 406), the signal (e.g., direct signal 404) may be used to determine a pseudorange to the satellite. All signals along the edge of thecone (both direct (404) and reflected (408)) are used to determine the Doppler frequency of the received signal. Signals outside of the edge 402 of the cone 400 are attenuated and not used. The pseudorange and Doppler frequency of all the received signals from various transmitters are processed within a navigation engine to determine the receiver’s location. The use of motion compensated signal correlation ensures the Doppler frequency is accurate (consistent with the Doppler associated with the LOS signal) and not compromised by multipath.

[0026] FIG. 2 is a functional block diagram of the radio signal receiver 106 of FIG. 1 in accordance with at least one embodiment of the invention. In one exemplary embodiment, the receiver 106 comprises an antenna 200, a front end 202, support circuits 204, motion module 208, at least one processor 210 and memory 212. When carried by a transport platform such as a vehicle, airplane, bicycle, person, etc., the receiver 106 and its antenna 200 are typically an indivisible unit where the antenna 200 moves with the platform. The SUPERCORRELATION™ technique operates based upon determining a component of motion of the signal receiving antenna that is in the direction of the source (e.g., GNSS satellite) of a received signal. Any mention of motion herein refers to the motion of the antenna 200. In most scenarios, the motion of the transport platform is the same as the motion of the antenna 200 and, as such, the following description assumes the motion of the platform, the receiver 106 and antenna 200 are the same.

[0027] The receiver’s front end 202 downconverts, filters, and samples (digitizes) the received signals in a manner that is well-known to those skilled in the art. The output of the receiver front end 202 is a digital signal containing signal data. The signal data of interest for performing motion compensation is a deterministic code, e.g., Gold code, used by the processor 210 to synchronize the receiver 106 to the GNSS transmission.

[0028] The at least one processor 210 may be any form of processor or combination of processors including, but not limited to, central processing units, microprocessors, microcontrollers, field programmable gate arrays, graphicsprocessing units, digital signal processors, and the like. The support circuits 204 may comprise well-known circuits and devices facilitating functionality of the processor(s). The support circuits 204 may comprise one or more of, or a combination of, power supplies, clock circuits, analog to digital converters, communications circuits, cache, displays, filters, and / or the like.

[0029] The memory 212 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 212 stores software and data including, for example, GNSS signals 214 (and / or representations of those signals), signal processing software 216, a motion model 218, navigation software 226 and data 220. The data 220 comprises a receiver position 222, motion hypotheses 224, Doppler frequencies 228, and various additional data used to perform the SUPERCORRELATION™ processing.

[0030] In operation, the at least one processor 210 accesses the buffered GNSS signals 214 and the at least one processor 210 correlates the received code from each satellite with locally generated codes to produce correlation results. The correlation results are processed as is well-known in the art to generate position information 222, e.g., the correlation results are used to determine pseudoranges and Doppler frequencies for each satellite and the pseudoranges and Dopplers are processed to compute the receiver position and velocity. The at least one processor 210 performs the SUPERCORRELATION™ processing to provide signals (phasor sequences) to phase adjust the complex correlation results such that the coherent integration period is extended, e.g., extended to one or more seconds, to improve signal reception. The phasor sequence is a time sequence of phase offsets where each phasor in the sequence adjusts the phase of a complex signal sample. The adjustment may be performed by adjusting the phase of each 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 complex correlation results.

[0031] The phasor is used to compensate for the motion of the receiver antenna within the correlation process to facilitate long correlation periods (e.g., one second) such that signals along the edge of the cone of sensitivity are processed with the long correlation period (i.e., enhanced signal processing gain).

[0032] In some embodiments, the GNSS signals may have been fully or partially processed before being buffered as part of the data. For example, the partially processed signals may include downconverted, filtered, and / or sampled GNSS signals. Fully processed signals may include complex correlation results.

[0033] The motion module 208 generates receiver motion information (i.e., a motion model 218) that is buffered as part of the data 220 and used by the at least one processor 210 to generate phasor sequences that are used to motion compensate the complex correlation results. The buffered data 220 may include motion module inputs, outputs or a combination of both. The motion model 218 may comprise motion measurements and / or computed anticipatory motion information. The motion model 218 is used to produce motion hypotheses 222 of the phasor sequences that estimate the motion compensation necessary to improve signal reception in a specific direction (i.e., the direction of the transmitter of the received signal). 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 the direction of the transmitter or the reflected signal (e.g. 408). In one embodiment, the motion module 208 uses the at least one processor 210 to generate the motion model 218 reflecting the motion of the receiver 106 in the direction of the transmitter or the reflected signal. In one embodiment, motion information may comprise a prediction of receiver velocity and heading (i.e., a motion model 218). In one alternative embodiment, the motion module 208 may comprise an inertial measurement unit (IMU) to provide platform (receiver) orientation and velocity information for the motion model.

[0034] FIG. 3 is a flow diagram of a method 300 of operation of the receiver (106 in FIGs. 1 and 2) in accordance with at least one embodiment of the invention. Themethod 300 may be implemented in software, hardware or a combination of both (e.g., using the at least one processor 210 and the motion module 208 of FIG. 2). The method 300 operates through execution of the signal processing software (216 of FIG. 2) and navigation software (226 of FIG. 2) using the at least one processor (210 of FIG. 2) to access and perform instructions of the software.

[0035] The method 300 begins at 302 and proceeds to 304 where signals are received at a receiver from at least one remote source (e.g., transmitters such as the plurality of GNSS satellites 102A, 102B, . . . of FIG. 1 ) in a manner as described with respect to FIG. 1. 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.

[0036] At 306, the data (e.g., GNSS signals, partially or fully processed signals, motion data, etc.) are stored (buffered) in memory such that the GNSS signals may be repeatedly processed with various phasor sequences representing various motion hypotheses. The data includes any information from which motion compensated correlation is performed.

[0037] At 308, the method 300 determines the receiver motion and creates a motion model representing receiver motion in the direction of the transmitter or the reflected signal of each received signal. Receiver motion may be measured using an IMU / GNSS navigation solution and / or computed from historical measured motion information.

[0038] At 310, the buffered data is processed using the SUPERCORRELATION™ technique to motion compensate the correlation results. During this process, the SUPERCORRELATION™ procedure generates a plurality of phasor sequence hypotheses (motion hypotheses) related to the motion information. 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 signalwith a code encoded in the received RF signal. The phasor sequence hypotheses are used to adjust, at a sub-wavelength accuracy, the complex carrier phase of the local signal. Such adjustment or compensation may be performed by adjusting a local oscillator signal, the received signal(s), or the correlation results. 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) of phasor sequence hypotheses containing estimates of a phase offset necessary to accurately correlate the received signals. All the hypotheses are tested to find the hypothesis that provides the best or optimal correlation result magnitude.

[0039] The motion estimates are typically hypotheses of the motion in a direction of interest such as in the direction of the satellite that transmitted the received signal or in a direction of a reflected signal, e.g., along the signal propagation path. As with all GNSS receivers, the satellite positions are known to the receiver through known ephemeris data. A comparison of correlation results over the direction hypotheses enables the method 300 to narrow the search space when processing subsequently received signals. Consequently, subsequent compensation is performed over a narrow search space.

[0040] 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 300 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 thecorrelation process is a plurality of phase-compensated correlation results - one phase-compensated correlation result value for each hypothesis for each received signal.

[0041] The method 300 processes the correlation results to find the “best” or optimal result for each received signal. In one embodiment, the method 300 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.

[0042] For example, assuming all other receiver parameters are known except receiver motion direction, the method 300 tests hypotheses with various phasor sequences that compensate for phase changes due to each direction hypothesis. The correct 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.

[0043] If additional receiver parameters (e.g., clock frequency and / or frequency rate) are unknown or not accurately known, those parameter offsets may also be expressed as phasor hypotheses and tested to optimize the correlation output across multiple parameters at once. These parameter offsets are used to correct inaccuracies in, for example, the receiver clock.

[0044] Through the use of the motion compensated correlation process, the improved signal reception in a specific direction forms a cone of sensitivity such that signals in the cone are used in the position location solution and signals outside thecone are rejected. The signals in a cone pointing at a specific satellite are deemed to be from that satellite even if the signal is a reflected signal.

[0045] At 312, all signals maximized by the motion compensated correlation process (i.e., signals along the edge of the cones of sensitivity) are processed to determine the Doppler frequency of those signals. In addition, at 314, signals that are known to be LOS signals are processed to determine the pseudorange to the transmitting satellite.

[0046] At 316, the method 300 adjusts the navigation solution weighting of pseudorange versus Doppler use in the navigation solution. The Dopplers can be used with confidence because the motion compensated correlation process ensures the Dopplers that are produced from LOS or NLOS signals are accurate (i.e., the signals were received along an edge of a cone of sensitivity pointed at a particular satellite or pointed at a reflection point of a reflected signal). However, pseudorange measurements may include delays caused by reflections in which case they should be downweighted in the navigation solution relative to the Doppler measurements. If sufficient pseudoranges are known with confidence, the navigation solution will be weighted to use the pseudoranges and Doppler measurements to determine receiver position and velocity. However, if there are insufficient pseudoranges or the confidence level of their accuracy is low, the navigation solution is weighted to utilize the Dopplers to determine receiver position and velocity.

[0047] At 318, the method executes the navigation software (i.e., a navigation engine). The Dopplers and pseudoranges derived from the compensated correlation results as well as the weighting determined in 316 are used by a traditional positioning or navigation solution (e.g., using a pseudorange and Doppler of each satellite transmitter from which signals were contained in the stored data) to generate the accurate position and velocity of the receiver.

[0048] At 320, the method queries if additional signals are to be processed. By processing a sequence of signals, a path of the receiver may be constructed. If thequery is affirmatively answered, the method 300 proceeds along path 324 to access additional signals and process them. If the query is negatively answered, the method 300 proceeds to 322 and ends.

[0049] 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.

[0050] 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 embodiments of the invention presented herein. Embodiments of the present invention are not intended to be limited to any scope of claim language.

[0051] 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.

[0052] 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 may be performed in any order or not at all, including substantially simultaneously, i.e., within tolerances of the systems executing the block, step, or module.

[0053] 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.

[0054] 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.

[0055] 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 performing signal processing in a radio signal receiver while the radio signal receiver is traveling through a parallel reflector environment, comprising: receiving at least one radio signal from at least one transmitter; determining a motion of the radio signal receiver; performing, using the at least one radio signal and the determined motion, motion compensated correlation in a direction of the at least one transmitter or a direction of a reflected signal to generate motion compensated correlation results; determining, from the motion compensated correlation results, a Doppler frequency of the at least one radio signal; adjusting at least one weighting of a navigation solution based upon the determined Doppler frequency; and executing the navigation solution.

2. The method of claim 1 , wherein the radio signal is a GNSS signal that includes a synchronization or acquisition code.

3. The method of claim 1 , wherein performing motion compensated correlation includes generating a plurality of phasor sequence hypotheses related to the determined motion of the radio signal receiver, wherein each phasor sequence hypothesis comprises a phase estimate that varies with motion parameters of the radio signal receiver.

4. The method of claim 3, wherein for each received radio signal, correlating the received radio signal with a plurality of phasor sequence hypotheses containing estimates of a phase offset to correlate the received radio signals.

5. The method of claim 3, further comprising producing a joint correlation output as a function of the correlation results resulting from all the phasor sequence hypotheses and received radio signals.

6. The method of claim 5, wherein the joint correlation output is a single value or a plurality of values that represent preferred hypotheses that provide an optimal correlation output.

7. The method of claim 6, wherein a cost function is applied to each set of correlation values for each received signal to find the optimal correlation output corresponding to one or more preferred phasor sequence hypothesis.

8. The method of claim 1 , further comprising processing signals that are line of sight signals to determine a pseudorange to the at least one transmitter.

9. The method of claim 8, wherein both the pseudorange and the Doppler frequency are used in the navigation solution and adjusting includes adjusting a weighting of the pseudorange versus the Doppler frequency used in the navigation solution.

10. The method of claim 9, wherein when a number of the pseudoranges are above a predetermined amount are known with confidence, the navigation solution is weighted to use the pseudoranges and the Doppler frequency to determine receiver position and velocity and, when the number of pseudoranges are below the predetermined amount or a confidence level of pseudorange accuracy is below a threshold, the navigation solution is weighted to utilize the Doppler frequency to determine receiver position and velocity.11 . Apparatus for performing signal processing in a radio signal receiver while the radio signal receiver is traveling through a parallel reflector environment, 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 least one radio signal from at least one transmitter;determining a motion of the radio signal receiver; performing, using the at least one radio signal and the determined motion, motion compensated correlation in a direction of the at least one transmitter or a direction of a reflected signal to generate motion compensated correlation results; determining, from the motion compensated correlation results, a Doppler frequency of the at least one radio signal; adjusting at least one weighting of a navigation solution based upon the determined Doppler frequency; and executing the navigation solution.

12. The apparatus of claim 11 , wherein the radio signal is a GNSS signal that includes a synchronization or acquisition code.

13. The apparatus of claim 11 , wherein performing motion compensated correlation includes generating a plurality of phasor sequence hypotheses related to the determined motion of the radio signal receiver, wherein each phasor sequence hypothesis comprises a phase estimate that varies with motion parameters of the radio signal receiver.

14. The apparatus of claim 13, wherein for each received radio signal, correlating the received radio signal with a plurality of phasor sequence hypotheses containing estimates of a phase offset to correlate the received radio signals.

15. The apparatus of claim 13, further comprising producing a joint correlation output as a function of the correlation results resulting from all the phasor sequence hypotheses and received radio signals.

16. The apparatus of claim 15, wherein the joint correlation output is a single value or a plurality of values that represent preferred hypotheses that provide an optimal correlation output.

17. The apparatus of claim 16, wherein a cost function is applied to each set of correlation values for each received signal to find the optimal correlation output corresponding to one or more preferred phasor sequence hypothesis.

18. The apparatus of claim 11 , further comprising processing signals that are line of sight signals to determine a pseudorange to the at least one transmitter.

19. The apparatus of claim 18, wherein both the pseudorange and the Doppler frequency are used in the navigation solution and adjusting includes adjusting a weighting of the pseudorange versus the Doppler frequency used in the navigation solution.

20. The apparatus of claim 19, wherein when a number of the pseudoranges are above a predetermined amount are known with confidence, the navigation solution is weighted to use the pseudoranges and the Doppler frequency to determine receiver position and velocity and, when the number of pseudoranges are below the predetermined amount or a confidence level of pseudorange accuracy is below a threshold, the navigation solution is weighted to utilize the Doppler frequency to determine receiver position and velocity.

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