Method, apparatus and system for environment mapping using radio signals

Abstract

A method, apparatus and system implement radio transmission from a transmitter for mapping an environment, which includes receiving a plurality of signals having a plurality of propagation paths from the transmitter (304), extracting from each signal, data representing a DoD, determining a transmitter location, determining a motion of at least one antenna of at least one receiver (306), generating a plurality of phasor sequences (308), determining a preferred hypothesis in a plurality of hypotheses for each received signal that optimizes a correlation result in a plurality of compensated correlation results (312), identifying a DoA for each of the plurality of received signals having a different propagation path using the determined hypothesis (314), determining a point of reflection from the DoA of each received signal, a receiver location, the transmitter location, and the DoD, and processing the points of reflection to map at least one reflection surface in the environment.

Description

METHOD, APPARATUS AND SYSTEM FOR ENVIRONMENT MAPPING USINGRADIO SIGNALSBACKGROUNDField

[0001] Embodiments of the present principles generally relate to radio signal processing and in particular, to a method, apparatus and system for environment mapping using radio signals.Description of the Related Art

[0002] Global Navigation Satellite System (GNSS) signals are broadcast by satellites and received by GNSS signal receivers within user equipment (UE), e.g., computer, tablet, cellular telephone, smartphone, intemet-of-things (loT) device, etc. Exemplary GNSS include the global positioning system (GPS), BeiDou, GLONASS, Galileo, etc. In many instances of use, the signals from the GNSS satellites are blocked or reflected by buildings and other structures - what is commonly referred to as an urban canyon. Some GNSS signal receivers only process received signals that are known to have traveled directly from the satellite to the receiver without reflection (i.e., commonly known as direct signals, straight line or line of sight (LOS) signals). Other GNSS signal receivers can utilize reflected signals in signal processing to enhance GNSS signal reception. Typically, to use the reflected signal, the receiver must accurately estimate the path length of the reflected signal (i.e., know the transmitting satellite position, know the reflector(s) position and know an estimate of the receiver position). Using well-known ray tracing techniques, the receiver can determine the path length of the reflected signal and can compute the signal time delay caused by the additional path length as compared to a LOS signal. The receiver compensates for the signal time delay such that the reflected signal can be used in the position solution.

[0003] To utilize the reflected signal, the receiver must know the structural environment proximate the receiver (i.e., the receiver must know the location and orientation of reflective surfaces). Such knowledge is typically contained in a three-dimensional map of the region surrounding the UE. Enhancing GNSS signal processing using 3D maps is commonly known as 3D mapping assisted (3DMA) positioning.

[0004] Creating 3DMA models that contain the reflected surface location and orientation (i.e., surface pose) is a tedious process requiring sophisticated processing and combination of satellite and ground photographs and / or video of cityscapes. Typically, vehicles with roof mounted cameras gather 3D imagery of a city by driving along every street. A combination of satellite and ground-based imagery produces a model of reflective surfaces. The model contains the location and orientation (i.e., pose) of the surfaces. The process of generating the information for the map and then creating the map itself is tedious and time consuming.

[0005] Therefore, there is a need for an improved method, apparatus and system for environment mapping.SUMMARY

[0006] Embodiments of the present principles generally relate to a method, apparatus and system for environment mapping as shown in and / or described in connection with at least one of the figures.

[0007] These and other features and advantages of the present principles can be appreciated from a review of the following detailed description, along with the accompanying figures in which like reference numerals refer to like parts throughout.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] So that the manner in which the above recited embodiments of the present principles can be understood in detail, a more particular description of the invention, briefly summarized above, 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.

[0009] FIG. 1 depicts a block diagram of a communication environment including a receiver that uses signals transmitted by a fifth generation (5G) base station transmitter to map one or more surfaces that define a portion of a cityscape in accordance with at least one embodiment of the present principles;

[0010] FIG. 2 depicts a high-level block diagram of a receiver in accordance with at least one embodiment of the present principles;

[0011] FIG. 3 depicts a flow diagram of a method of signal processing of a receiver in accordance with at least one embodiment of the present principles; and

[0012] FIG. 4 depicts a flow diagram of a method of environment mapping of a receiver in accordance with at least one embodiment of the present principles.

[0013] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. The figures are not drawn to scale and may be simplified for clarity. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.DETAILED DESCRIPTION

[0014] Embodiments of the present principles generally relate to methods, apparatuses and systems for environment mapping using radio signals. While the concepts of the present principles are susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and are described in detail below. It should be understood that there is no intent to limit the concepts of the present principles to the particular forms disclosed. On the contrary, the intent is to cover all modifications, equivalents, and alternatives consistent with the present principles and the appended claims.

[0015] Radio transmissions are used in various communications and positioning systems. For example, cellular telephone signals are broadcast from antennas located on various structures, such as water towers, purpose-built antenna masts, buildings, etc. The signals can interact with nearby structures, such as urban canyon of buildings and other structures, that block or reflect the signals. Fifth generation (5G) cellular signals are directionally transmitted from base station antennas, such phased array antennas.

[0016] The direction in which the transmission propagates is encoded into the transmitted signal. Within the transmitted signal is a field that includes what the 5G standard defines as anAngle of Departure (AoD). However, the AoD contains both horizontal and elevation angles that together form a direction of departure (DoD). Embodiments of the present principles can use the more accurately descriptive Direction of Departure (DoD) rather than the 5G standard AoD nomenclature, but those skilled in the art will understand that the departure direction comprises both horizontal and elevation angles in 3D space and is equivalent to the standard’s AoD nomenclature.

[0017] A 5G signal also comprises a field containing the location of the base station antenna. The location is defined by geo-coordinates that accurately identifies the base station antenna location. As such, a 5G receiver receives and decodes the 5G signal to extract the base station antenna location of each transmitting antenna within its reception area.

[0018] Embodiments of the present principles include method, apparatuses and systems that use transmissions from one or more transmitters to map one or more surfaces that define a portion of a cityscape. Digital communications systems such as cellular 5G systems utilize encoded digital signals to improve communication throughput and security. These systems utilize a deterministic digital code, such as an acquisition code, to facilitate signal acquisition. Such a digital code is deterministic by the receiver and can be repeatedly broadcast by the transmitter to enable the receivers to acquire and receive the transmitted signals. Using such deterministic codes combined with an accurate motion model of a receiver, embodiments of the present principles are useful for isolating signal propagation paths along specific directions of arrival (DoA). The signal can propagate directly (e.g., line-of-sight (LOS)) or via a reflection (e.g., non-line-of-sight (NLOS)). The technique for performing this DoA determination using receiver motion information 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 2024 / 0045077, published 8 February 2024, which are hereby incorporated herein by reference in their entireties. In some embodiments, a receiver and the transmitter can be operating within an urban canyon defined by surrounding buildings. The receiver uses this DoA data regarding transmissions from the transmitter in combination with an accurate receiver position, accurate transmitter antenna location and the transmission Direction of Departure (DoD) data to determine the locations ofsurfaces that caused reflected signals. The computed pose of surfaces, such as building walls, are relative to the known location of the receiver.

[0019] In one exemplary embodiment, a user equipment (UE), comprising a receiver, can be transported through a cityscape containing a transmitter and can identify signal propagation paths (LOS and NLOS). With knowledge of the location of the transmitter, knowledge of the receiver position, and knowledge of the transmission DoD, embodiments of the present principles determine the propagation paths for LOS and NLOS signals. In various embodiments, receiver and transmitter positions can be apriori provided or can be determined by the receiver. These positions can be absolute (world geographic coordinates) or can be relative (arbitrary coordinate system). The receiver isolates the LOS and NLOS signals to use the reflected (NLOS) signals to determine the reflection points of the signals. In some embodiments, processing of these isolated reflected signals,, with the knowledge of the receiver’s position and knowledge of the transmission DoD, results in a determination of the location of the reflective surfaces. The functionality of embodiments of the present principles can be embedded into cellular telephones, Internet of Things (loT) devices, mobile computers, tablets, purpose-built environment mapping devices and the like. Embodiments find use on any moving receiver that receives signals having a code that can be correlated with a locally generated code and that contain the DoD data of the directionally transmitted signal. One example of such a signal is a 5G cellular signal, but any signal can be used where the DoD and transmitter location are known. In some embodiments, the receiver only needs to be able to utilize a deterministic acquisition code contained in the received signal and to decode the transmitted signal DoD information and transmitter location information. Although the receiver can receive the signal and utilize a full data message of the signal (i.e., cellular enabled), the receiver does not have to be a fully enabled communication device to be used in embodiments of the present principles.

[0020] In at least some embodiments, as the receiver traverses an area, the receiver collects DoA and DoD data for the reflected signals. The receiver can be aware of its position through the use of a global navigation satellite system (GNSS) receiver and / or an inertial guidance system. Alternatively or in addition, a receiver of the present principles can know or infer its position via visual odometry or visual positioning of known objects and their positions, (e.g., landmark locations) and use the landmark position to determine the position of the receiver.Alternatively or in addition, if the initial position of the receiver relative to some absolute world coordinate system (e.g., latitude, longitude, altitude) is unknown, the receiver can adopt an initial position and orientation in an arbitrary coordinate frame in which its trajectory is subsequently tracked. In the 5G example, the receiver can know the transmitter location by receiving and decoding the 5G transmitter antenna position data contained in the 5G signal. From the known receiver position, transmitter position and a plurality of DoA and DoD vectors, embodiments of the present principles can accurately compute the location of one or more reflective surfaces relative to the receiver position in the adopted coordinate frame. In some embodiments, the signal reflection points representing the reflective surfaces can be interpolated into planar surfaces. As such, embodiments of the present principles provide a method, apparatus, and system for generating a map of one or more surfaces that are proximate a transmitter-receiver pair.

[0021] In accordance with the present principles, many receivers can be operated in an area and transmit their data (e.g., surface maps or raw data used to compute surface maps) to one or more central processing centers to be combined into a comprehensive 3D model of a cityscape.

[0022] In some examples herein, it is assumed that the reflection surfaces are planar. It will be apparent to one skilled in the art that further embodiments of the present principles can accommodate reflections from non-planar surfaces.

[0023] In other examples herein, the determined surface locations can be used to confirm the accuracy of existing three-dimensional maps. For example, in some embodiments, a three- dimensional city map can be used by a cellular telephone handset to determine which GNSS satellites have a direct signal path to the handset and which GNSS signals are blocked or attenuated by buildings. An embodiment of the present principles operating in the handset, can use cellular signals to determine surfaces proximate the handset. The determined surfaces can be compared to the existing three-dimensional city map surfaces to confirm accuracy of the map. Map errors can be reported to the map provider for correction. Alternatively or in addition, in some embodiments, discovering an error can cause the handset to not use the map at this particular location. Such an error can be caused by a large temporary object (i.e., a transient surface, such as a bus) being parked proximate the handset. In other embodiments,surface information computed by the handset can be used to fill gaps or holes in an existing 3D map. In further embodiments, the existing 3D map can have captured transient surfaces that handset data can identify as transient such that the existing 3D map can be corrected.

[0024] In some embodiments of the present principles, signal processing can be performed locally on a moving platform, such as in user equipment. Alternatively or in addition, in some embodiments, the receiver motion information, receiver position information, DoD transmission information and transmitter position can be gathered at the moving platform and communicated (wired or wirelessly) to a server for remote processing in real-time or at a later time.

[0025] FIG. 1 depicts a block diagram of a communication environment including a receiver that uses signals transmitted by a fifth generation (5G) base station transmitter to map one or more surfaces that define a portion of a cityscape in accordance with at least one embodiment of the present principles. In the embodiment of FIG. 1, the communication environment 100 includes at least one receiver 104 for receiving signals broadcast from a transmitter 128. In the communication environment 100 of FIG. 1, the at least one receiver 104 is carried by a person 102 in a defined space (e.g., urban canyon) 130. As the at least one receiver 104 moves through the space 130, the receiver 104 receives signals from the signal transmitter 128 and determines the locations of one or more reflective surfaces 118 relative to the receiver. In the communication environment 100 of FIG. 1, the at least one receiver 104 is operating in a high multipath environment such as an urban canyon 130. Each of the at least one receivers 104 of FIG. 1 comprises a mapping module (described in detail with respect to FIG. 2 below) configured to receive and process signals transmitted by the transmitter 128.

[0026] In the communication environment 100 of FIG. 1, the transmitter 128 transmits a signal that contains the transmitter location (e.g., antenna geocoordinates) and the DoD of the transmitted signal. Such transmitters can include, but are not limited to, 5G cellular transmitters. In the communication environment 100 of FIG. 1, an exemplary 5 G transmitter comprises a 5Gbase station 106, an antenna tower 108 and a directional antenna 110, typically, a phased-array antenna capable of directing transmitted antenna beams.

[0027] In the embodiment of the communication environment 100 of FIG. 1, the receiver 104 can enter the space 130 knowing its position either from at least one of: (1) a global navigation satellite (GNSS) receiver and / or an inertial navigation system (INS) or (2) position knowledge from a map or visual odometry / positioning. A mapping module of the receiver can use a known location of the transmitter 128, the known receiver position, DoD information of the transmitted signal and receiver motion information (a motion model) in combination with the received reflected signals (NLOS signals) to determine an accurate surface pose as the receiver traverses the space.

[0028] More specifically, in the communication environment 100 of FIG. 1, as the person (or other moving platform, such as a vehicle) 102 carries the receiver 104 from position 114- 1, to 114-2, to 114-3, and so on, the receiver 104 can determine the signal DoA while decoding the DoD of the signals 118-1, 118-2, 118-3 and the location of the transmitter 128. Using ray tracing techniques, the receiver 104 can determine the precise location of the reflection 116-1, 116-2, 116-3 that occur as the receiver 104 moves with the person 102. The reflection points determined by the receiver 104 form a point cloud that can be interpolated into a surface 119. By collecting many reflection points, the receiver 104 can create a map or model of the surrounding area.

[0029] As described in detail below, in some embodiments the at least one receiver 104 can use a SUPERCORRELATION™ technique 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 2024 / 0045077, published 8 February 2024, which are hereby incorporated herein by reference in their entireties. The technique determines a direction of arrival (DoA) of signals received at a receiver (i.e., received signals) from the transmitter - both LOS and NLOS signals. As the receiver 104 moves (represented by arrow 132), the mapping module computes motion information representing motion of the receiver 104. The motion information is used to perform motion compensated correlation of the received signals. From the motion compensated correlation process, the mapping module estimates the DoA of the received signals. The mapping module uses the receiver position and the transmitter location along with the DoA and DoD data to determine a location of reflective surfaces of the space 130. Theintersection of a plurality of DoA and DoD vectors generated as the receiver moves along path 132 can be used to identify the location of reflective surfaces as described in detail below.

[0030] Although the description above assumed the mapping processing was performed in the receiver 104, in other embodiments, the receiver position, transmitter position, DoA, DoD and correlation results can be transmitted to a server for real-time or ex post facto processing at a remote location to produce the surface map. In other embodiments, the data from many receivers can be collected at a remote server for mapping large portions of a cityscape and produce a 3DMA model. In some embodiments, the surfaces can be used to augment or correct an existing 3DMA model.

[0031] For example and with reference back to the communication environment 100 of FIG. 1, a person 124 (or other moving platform) can be moving through the space 130 carrying a receiver 126. The receiver 126 (or remote server) processes the position and signal direction information to determine reflective surface 134. In some instances, the surface can be determined to be a transient reflector when it disappears, for example when the truck 122 drives away, or when the mapping module compares the surface to a known 3DMA model and the transient surface does not exist in the 3DMA model. In other embodiments, a first receiver can discover the reflective surface, but a second receiver does not discover that same surface. In such instances, the reflective surface will be deemed a transient reflector and not used in an environment map.

[0032] FIG. 2 depicts a high-level block diagram of a receiver in accordance with at least one embodiment of the present principles. The receiver 104 of FIG. 2 illustratively comprises an antenna 202 coupled to a mapping module 200. The mapping module 200 comprises a receiver front end 204, a signal processor 206, and a motion module 208. The receiver 104 can form a portion of a user equipment (UE) including, but not limited to, a laptop computer, mobile phone, tablet computer, Internet of Things (loT) device, purpose built positioning device, a purpose built mapping device, and the like.

[0033] In the receiver 104 of FIG. 2, the mapping module 200 and the antenna 202 are an indivisible unit where the antenna 202 moves with the positioning module 108. The operation of the SUPERCORRELATION™ technique operates based upon determining the motion ofthe signal receiving antenna. Any mention of motion herein refers to the motion of the antenna 202. In some embodiments, the antenna 202 can be separate from the mapping module 200. In such embodiments, the motion estimate used in the motion compensated correlation process is the motion of the antenna 202. In various embodiments, the motion of the mapping module 200 is the same as the motion of the antenna 202 and, as such, the following description will assume that the motion of the mapping module 200 and antenna 202 are the same.

[0034] As described above, the mapping module 202 of FIG. 2 comprises the receiver front end 204, the signal processor 206 and the motion module 208. The receiver front end 204 downconverts, filters, and samples (digitizes) the received signals in a manner that is well- known to those skilled in the art. In one embodiment, the receiver front end 204 receives and decodes a 5G signal to, at a minimum, extract the deterministic code or training / acquisition data, the DoD data and transmitter location information.

[0035] The signal processor 206 of the receiver 104 of FIG. 2 comprises at least one processor 210, support circuits 212 and memory 214. The at least one processor 210 can 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 212 can comprise well-known circuits and devices facilitating functionality of the processor(s). The support circuits 212 can 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.

[0036] The memory 214 of the receiver 104 of FIG. 2 can include one or more forms of non-transitory computer readable media including one or more of, or any combination of, readonly memory or random-access memory. The memory 214 stores software and data including, for example, signal processing software 216, mapping software 232 and data 218. The data 218 can include at least the receiver location 220, direction of arrival (DoA) vectors 222 (collectively, DoA data), direction of departure vectors 223 (collectively, DoD data) transmitter location 224, motion information 226, a surface map 228, and various other data used to perform the SUPERCORRELATION™ processing. In accordance with the present principles, the signal processing software 216, when executed by the one or more processors 210, performs motion compensated correlation upon the received signals to estimate the DoAvectors for the received signals. The motion compensated correlation process is described in detail below.

[0037] As described below in detail, the DoA vectors 222, the DoD vectors, the receiver position 220 and the transmitter location 224 are used by the mapping software 208 to determine the pose of reflective surfaces and thus determine a surface map 228 in accordance with the present principles. In some embodiments, the data 218 stored in memory 214 can also include signal estimates, correlation results, motion compensation information, motion information, motion and / or other receiver parameter hypotheses, position information and the like (e.g., other data 230).

[0038] In accordance with the present principles, the motion module 208 can generate a motion estimate for the antenna 202. The motion module 208 can include an inertial navigation system (INS) 234 as well as a global navigation satellite system (GNSS) receiver 236 such as GPS, GLONASS, GALILEO, BEIDOU, etc. In the embodiment of FIG. 2, the INS 234 can include one or more of, but not limited to, a gyroscope, a magnetometer, an accelerometer, and the like. To facilitate motion compensated correlation, the motion module 208 produces motion information (sometimes referred to as a motion model) including at least a velocity of the antenna 202 in the direction of interest, such as an estimated direction of a reflection point of a received reflected signal. In some embodiments, the motion information can also include estimates of platform orientation or heading including, but not limited to, pitch, roll and yaw of the module 200 / antenna 202. Generally, as described in more detail below, in some embodiments the receiver 104 can test every direction and iteratively narrow the search to one or more directions of interest. In some embodiments, the receiver 104 uses a priori knowledge of the receiver position, 3DMA models, transmitter location, and the like to narrow the range of DoAs to be searched.

[0039] Alternatively or in addition, in some embodiments signal processing and / or map processing of the present principles can be performed remote from the receiver 104. In such embodiments, the receiver can transmit data through the cloud 250 (or other communications network) to a server 260 for processing. The server 260 can include at least one processor 262, support circuits 264 and memory 266. The at least one processor 262 can 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 264 can comprise well-known circuits and devices facilitating functionality of the processor(s). The support circuits 264 can 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.

[0040] In such embodiments, the memory 266 can comprise one or more forms of non- transitory computer readable media including one or more of, or any combination of, readonly memory or random-access memory. The memory 266 can store software and data including, for example, signal processing software 268, mapping software 270 and data 272. The data 272 comprises the receiver location, direction of arrival (DoA) vectors (collectively, DoA data), direction of departure (DoD) vectors (collectively, DoD data), transmitter location, motion information, a surface map, and various other data used to perform the SUPERCORRELATION™ processing. The signal processing software 268, when executed by the one or more processors 262, can perform motion compensated correlation upon the received signals to estimate the DoA vectors for the received signals. The motion compensated correlation process is described in detail below.

[0041] In such embodiments, the processing of the present principles can be accomplished remotely either in real-time as data is collected or ex post facto after the data is collected. In some embodiments, the server can collect data from many receivers to facilitate creating or correcting 3DMA maps of cityscapes. In some embodiments, the SUPERCORRELATION processing that leads to the DoA vectors, can be performed in the receiver 104 such that the receiver sends the receiver and transmitter locations, DoA vectors, and DoD vectors to the server for processing into surface maps. Alternatively or in addition, in some embodiments the raw received signals can be sent to the server such that all the signal processing is performed remotely.

[0042] In some embodiments of the present principles, the receiver 104 performs the SUPERCORRELATION™ technique to motion compensate the received signals arriving from the transmitter 128. These signals can arrive unimpeded as a direct LOS signal (not shown). Other signals along paths 118-1, 118-2 and 118-3 reflect from the surfaces (e.g., surface 119) and arrive at the receiver 104. For example and as depicted in FIG. 1, thetransmitted radio signal leaves the transmitter 128 and propagates to the surface 119 where the signal contacts the surface 119 and an angle of incidence (<I). The reflected signal leaves the surface 119 and an angle of reflection (<R) that is equal to <1. At a point 116-1 along the surface, the transmitted signal reflects from the wall and the signal on path 116-1 impinges upon the receiver antenna. The DoA of these signals forms the DoA vectors computed by the receiver 104.

[0043] In some embodiments, to determine an accurate reflector location, the receiver 104 implements an accurate understanding of its position relative to the transmitter 128 and an accurate understanding of the motion of the receiver. That is, in some embodiments, the receiver 104 receives the signals from the transmitter 128 and correlates those signals with locally generated signals to determine correlation results. These correlation results are motion compensated using the receiver motion to correct for doppler and doppler rate changes due to the receiver motion and extend the coherent integration period of the receiver such that accurate correlation results are used in determining time of arrival and, therefore, extra path length to a sub -wavelength level.

[0044] The DoA vectors require processing to enable accurate reflector positioning. The DoA vector estimates are used to define a search space of directions from which signals can arrive. In some embodiments, if the receiver 104 is using a 3DMA model of the environment, the receiver can estimate the reflection point and create a set of hypotheses for the DoA of received signals. By testing each hypothesis against the DoA measurements over time, the receiver converges upon an accurate surface pose. In some embodiments, a receiver of the present principles can implement techniques such as Simultaneous Localization and Mapping for converging upon an accurate surface pose. As such, a signal arriving from a particular direction can be isolated from other reflected signals and the isolated signal processed with other isolated signals to generate accurate reflector position information that can be used to produce a map. Without the use of a motion compensated correlation technique (e.g., SUPERCORRELATION™) in accordance with the present principles, the signals could not be isolated according to angle of arrival to enable a transmitter to be used for environment mapping.

[0045] In some embodiments, surface locations can be determined relative to a position of a receiver of the present principles. The coordinate system can be arbitrary or based upon world geo-coordinates (e.g., GNSS coordinates). In some embodiments, the surface position can be mapped in an arbitrary coordinate system and subsequently aligned to a world coordinate system when a world coordinate reference becomes known.

[0046] FIG. 3 depicts a flow diagram of a method of signal processing of a receiver in accordance with at least one embodiment of the present principles. More specifically, FIG. 3 is a flow diagram of a method 300 of operation for the signal processing software 216 in accordance with at least one embodiment of the present principles. The method 300 can be implemented in software, hardware or a combination of both (e.g., using the signal processor 206 of FIG. 2).

[0047] The method 300 begins at 302 and proceeds to 304 during which signals are received at a receiver from a remote source (e.g., transmitter 128), for example, in a manner as described with respect to FIGs. 1 and 2. For example and as described above, in some embodiments, each received signal comprises a synchronization or acquisition code, i.e., a deterministic code, DoD data and a transmitter location, extracted from the radio frequency (RF) signal received at the antenna. The process of downconverting the RF signal and extracting the digital code is well known in the art and as such will not be described in detail herein. The method 300 can proceed to 306.

[0048] At 306, motion information is received from the motion module 208, for example, of FIG. 2. The motion information includes an estimate of the motion of the receiver 104 of FIG. 1, such as, one or more of velocity, heading, orientation, and the like. The method 300 can proceed to 308.

[0049] At 308, a plurality of phasor sequence hypotheses related to a direction of interest of the received signal are generated, such as, direction of the transmitter or direction of one or more reflections. These hypotheses include a plurality of local signals representing code phase estimates. Each phasor sequence hypothesis includes a series of phase offsets that vary with parameters of the receiver such as motion, frequency, DoA of the received signals, and the like. The signal processing of the present principles correlates a local code encoded in a localsignal with a code encoded in the received RF signal. In one embodiment, the phasor sequence hypotheses are used to adjust, at a sub -wavelength accuracy, the carrier phase of the local signal over one or more periods (lengths) of the received code. In some embodiments, such adjustment or compensation can be performed by adjusting a local oscillator signal, the received signal(s), and / or the correlation result to produce a phase compensated correlation result. In some embodiments, the signals and / or correlation results can be complex signals comprising in-phase (I) and quadrature phase (Q) components. The method of the present principles applies each phase offset in the phasor sequence to a corresponding complex sample in the signals or correlation results. If the phase adjustment is or includes an adjustment for receiver motion, then the result is a motion compensated correlation result. The method 300 can proceed to 310.

[0050] At 310, for each received signal, the received signals are correlated with a set(plurality) of direction hypotheses containing estimates of a phase offset necessary to accurately correlate the received signals arriving from particular directions. There is a set of hypotheses representing a search space for each received signal and each parameter of interest, such as, motion, frequency, frequency rate, DoA, etc.

[0051] In one embodiment, since the signal is received from a single transmitter, the set of hypotheses for newly received signals from the transmitter 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 transmitter. The values can 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 hypotheses are used as parameters to form the phase-compensated phasors to phase compensate the correlation process. As such, the phase compensation can be applied to the received signals, the local frequency source (e.g., an oscillator), and / or the correlation result values. The hypotheses collectively form a search space within which the method tests each of the hypotheses to determine a preferred hypothesis. In addition to searching over the DoA space, the method 300 can also apply hypotheses related to other parameters such as oscillator frequency to correct frequency and / or phase drift, and / or heading to ensure the correct motion compensation is being applied. The result of the correlation process is a plurality of phase-compensated correlation results - in some embodiments, one phase-compensated correlation result value for each hypothesis foreach received signal. The reflected signals from the single transmitter are naturally synchronized to it. Any drift and perturbations in the transmitter oscillator are contained in all the reflected signals. The receiver oscillator can therefore easily be referenced against the transmitter oscillator using the line of sight signal and / or any of the reflected signals once the Doppler effect from the receiver motion has been accounted for. The method 300 can proceed to 312.

[0052] At 312, the correlation results are processed to find the “best” or optimal result for each received signal (i.e., isolate each signal using an optimal DoA hypothesis). The correlation output can 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 some embodiments, a cost function can be applied to each set of correlation values for each received signal to find the optimal correlation output corresponding to a preferred hypothesis or hypotheses. The correlation output reveals the frequency and frequency rate offset between the receiver oscillator and the transmitter oscillator, enabling the receiver to be synchronized to the transmitter accordingly as well as determine the DoA of the signal. The method 300 can proceed to 314.

[0053] At 314, the DoA vector of each received signal is identified from the optimal correlation result for the signal. The received signals along the DoA vector typically have the strongest signal to noise ratio and represent line of sight (LOS) propagation or NLOS propagation having a single reflection point. As such, using motion compensated correlation enables the receiver 104 to identify the DoA vector of the received signal(s).

[0054] In other embodiments, rather than using the largest magnitude correlation value, other test criteria can be used. For example, in some embodiments the progression of correlations can be monitored as hypotheses are tested and a cost function can be applied that indicates the best hypotheses when the cost function reaches a minimum (e.g., a small Euclidean distance amongst peaks in the correlation plots). As such, in some embodiments the correlation output can be a correlation value or a group of values. In other embodiments, additional hypotheses can be tested in addition to the DoA hypotheses to, for example, ensure the motion compensation (i.e., speed and heading) is correct. The method 300 can proceed to

[0055] At 316, the DoA associated with the preferred hypotheses is used to isolate the received signals and their associated motion compensated correlation results. These correlation results can be used by the mapping software to create, correct, or update a 3D map of the environment. The method 300 ends at 316.

[0056] FIG. 4 depicts a flow diagram of a method of environment mapping of a receiver in accordance with at least one embodiment of the present principles. That is, FIG. 4 is a flow diagram of a method 400 of operation of the mapping software 232 in accordance with at least one embodiment of the present principles. The method 400 can be performed locally within the receiver and / or can be performed remotely on a server. If performed remotely, the estimated receiver position, correlation results for the received signals, DoA data, DoD data, transmitter location, and other information are transmitted from the receiver to the remote server for processing in accordance with method 400.

[0057] The method 400 can begin at 402 and proceed to 404 during which a receiver position, DoA data, DoD data and transmitter location is accessed / received. In some embodiments, the position is the current position of the receiver (i.e., the GNSS / INS position); the DoA data is the DoA of the received signal determined by the signal processing software 232; and the DoD data is extracted from the received signal. The transmitter location can be extracted from the received signal or can be determined from data stored in a database located at transmitter locations. Characteristics of the received signal or data extracted from the received signal can be used to determine the transmitter and / or transmitter location within the database. The method 400 can proceed to 406.

[0058] At 406, in one embodiment, a query is generated to determine whether the DoA and DoD are aligned (from opposite directions). If the query is affirmatively answered, the received signal is deemed a direct or LOS signal and not directly used for surface mapping. However, in some embodiments the knowledge of a LOS signal can be used to update the map information. For example, if the existing map shows that a building is expected in a given location that would block a LOS signal, but the reception of the LOS information indicates that this building no longer exists or that the map was incorrect, this is useful information to be used to update the map, for example to determine that the building was a transient object. The method 400 can proceed to 412.

[0059] At 412, the knowledge of an LOS signal can be used to determine that an object is a transient object. Referring back to 406, if the query is negatively answered, the received signal is deemed a reflected or NLOS signal and the method 400 proceeds to 408.

[0060] At 408, ray tracing is performed to identify the intersection point of a vector in the DoA direction and a vector in the DoD direction. The intersection point in 3D space is the reflection point. The method 400 can proceed to 410.

[0061] At 410, the reflection point geo-coordinates are output. At 410, the reflection point is processed. That is, in one embodiment, the reflection points can be added to determine at least one of a representation of a surface of an obj ect responsible for the reflection points and / or a map of the environment. That is, in some embodiments, determined reflection points can be added to an existing map as new surface points. The reflection point can also be used to confirm the location of an existing surface in a map. Once a group of reflection points are produced as the receiver 104 moves through the space 130 of FIG.1, the group of points can be processed to determine a surface that causes the reflection. As reflection points are processed, including reflection points from other receivers in the area, the various surfaces can be aggregated to create a comprehensive 3D model of, for example, the cityscape. In some embodiments, the reflection points can be compared to existing models to determine surfaces in the model that were transient reflectors that should be removed from the model. Similarly, the reflection points can be used to fill gaps in existing 3D models. The method 400 can proceed to 414.

[0062] At 414, it is determined whether another signal is to be processed. If the query is affirmatively answered, the method 400 returns to 404. If the query is negatively answered, the method 400 can end at 416.

[0063] In some embodiments, a method for mapping an environment using signals transmitted from a transmitter includes receiving a plurality of signals transmitted from the transmitter, where the plurality of signals comprise a plurality of propagation paths, extracting from each signal in the plurality of signals data representing a direction of departure, determining a location of the transmitter, determining a motion of at least one antenna of at least one receiver of the plurality of signals transmitted from the transmitter, generating a plurality of phasors sequences, where each phasor sequence represents a hypothesis based onmotion of the at least one antenna and a direction of arrival estimate for each of the plurality of the received signals having a different propagation path, compensating the received signals, a plurality of local signals or correlation results for correlating the received signals with the local signals using the plurality of phasor sequences based on the plurality of hypotheses regarding the motion of the at least one antenna of the at least one receiver and the direction of arrival to generate a plurality of compensated correlation results, determining a preferred hypothesis in the plurality of hypotheses for each received signal that optimizes each correlation result in the plurality of compensated correlation results, identifying a direction of arrival for each of the plurality of received signals having a different propagation path using the determined hypothesis, determining a point of reflection from the direction of arrival of each received signal in the plurality of received signals having a different propagation path, a receiver location, the transmitter location, and the direction of departure, and processing the points of reflection to map at least one reflection surface in the environment.

[0064] In some embodiments, ray tracing is performed to identify a point of reflection.

[0065] In some embodiments, a point of reflection is defined as an intersection point of a vector in the direction of arrival and a vector in the direction of departure.

[0066] In some embodiments, the at least one receiver comprises two or more receivers and the points of reflection determined by each of the two or more receivers are added to map the at least one reflection surface in the environment.

[0067] In some embodiments, the preferred hypothesis is determined by at least one of a cost function that identifies the preferred hypotheses when the cost function reaches a minimum or when the cost function identifies a largest magnitude correlation value.

[0068] In some embodiments, the method further comprises determining if the direction of arrival of a signal and the direction of departure of the signal are aligned to determine if the signal is a line of sight signal.

[0069] In some embodiments, determined line of sight signals are not directly used for surface mapping but are used to update mapping information such as to identify transient objects in the mapping.

[0070] In some embodiments, an apparatus for mapping an environment using signals transmitted from a transmitter includes at least one processor and a memory accessible to the at least one processor. In some embodiments, the memory has stored therein at least one of programs or instructions that when executed by the processor configure the apparatus to receive a plurality of signals transmitted from the transmitter, where the plurality of signals comprise a plurality of propagation paths, extract from each signal in the plurality of signals data representing a direction of departure, determine a location of the transmitter, determine a motion of at least one antenna of at least one receiver of the plurality of signals transmitted from the transmitter, generate a plurality of phasors sequences, where each phasor sequence represents a hypothesis based on motion of the at least one antenna and a direction of arrival estimate for each of the plurality of the received signals having a different propagation path, compensate the received signals, a plurality of local signals or correlation results for correlating the received signals with the local signals using the plurality of phasor sequences based on the plurality of hypotheses regarding the motion of the at least one antenna of the at least one receiver and the direction of arrival to generate a plurality of compensated correlation results, determine a preferred hypothesis in the plurality of hypotheses for each received signal that optimizes each correlation result in the plurality of compensated correlation results, identify a direction of arrival for each of the plurality of received signals having a different propagation path using the determined hypothesis, determine a point of reflection from the direction of arrival of each received signal in the plurality of received signals having a different propagation path, a receiver location, the transmitter location, and the direction of departure, and process the points of reflection to map at least one reflection surface in the environment.

[0071] In some embodiments, ray tracing is performed to identify a point of reflection. In some embodiments, a point of reflection is defined as an intersection point of a vector in the direction of arrival and a vector in the direction of departure.

[0072] In some embodiments, the at least one receiver comprises two or more receivers and the points of reflection determined by each of the two or more receivers are added to map the at least one reflection surface in the environment.

[0073] In some embodiments, a preferred hypothesis is determined by at least one of a cost function that identifies the preferred hypotheses when the cost function reaches a minimum or when the cost function identifies a largest magnitude correlation value.

[0074] In some embodiments, the apparatus is further configured to determine if the direction of arrival of a signal and the direction of departure of the signal are aligned to determine if the signal is a line of sight signal.

[0075] In some embodiments, determined line of sight signals are not directly used for surface mapping but are used to update mapping information such as to identify transient objects in the mapping.

[0076] In some embodiments, a system for mapping an environment using signals transmitted from a transmitter includes at least one receiver comprising a respective antenna, a motion module, at least one transmitter, and an apparatus including at least one processor and at least one memory for storing programs and instructions. In some embodiments, when the programs and instructions are executed by the processor, cause the apparatus to perform operations including receiving a plurality of signals transmitted from the transmitter, where the plurality of signals include a plurality of propagation paths, extracting from each signal in the plurality of signals, data representing a direction of departure, determining a location of the transmitter, determining, using the motion module, a motion of the antenna of the at least one receiver, generating a plurality of phasors sequences, where each phasor sequence represents a hypothesis based on motion of the antenna of the at least one receiver and a direction of arrival estimate for each of the plurality of the received signals having a different propagation path, compensating the received signals, a plurality of local signals or correlation results for correlating the received signals with the local signals using the plurality of phasor sequences based on the plurality of hypotheses regarding the motion of the at least one antenna of the at least one receiver and the direction of arrival to generate a plurality of compensated correlation results, determining a preferred hypothesis in the plurality of hypotheses for each received signal that optimizes each correlation result in the plurality of compensated correlation results, identifying a direction of arrival for each of the plurality of received signals having a different propagation path using the determined hypothesis, determining a point of reflection from the direction of arrival of each received signal in the plurality of receivedsignals having a different propagation path, a receiver location, the transmitter location, and the direction of departure, and processing the points of reflection to map at least one reflection surface in the environment.

[0077] In some embodiments, ray tracing is performed to identify a point of reflection. In some embodiments, a point of reflection is defined as an intersection point of a vector in the direction of arrival and a vector in the direction of departure.

[0078] In some embodiments, the at least one receiver comprises two or more receivers and the points of reflection determined by each of the two or more receivers are added to map the at least one reflection surface in the environment.

[0079] In some embodiments, the preferred hypothesis is determined by at least one of a cost function that identifies the preferred hypotheses when the cost function reaches a minimum or when the cost function identifies a largest magnitude correlation value.

[0080] In some embodiments, the system further performs the operation of determining if the direction of arrival of a signal and the direction of departure of the signal are aligned to determine if the signal is a line of sight signal.

[0081] In some embodiments, determined line of sight signals are not directly used for surface mapping but are used to update mapping information such as to identify transient objects in the mapping.

[0082] 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.

[0083] Those skilled in the art will also appreciate that, while various items are illustrated as being stored in memory or on storage while being used, these items or portions of them can be transferred between memory and other storage devices for purposes of memorymanagement and data integrity. Alternatively, in other embodiments some or all of the software components can execute in memory on another device and communicate with the illustrated computer system via inter-computer communication. Some or all of the system components or data structures can also be stored (e.g., as instructions or structured data) on a computer-accessible medium or a portable article to be read by an appropriate drive, various examples of which are described above. In some embodiments, instructions stored on a computer-accessible medium separate from the computing device 500 can be transmitted to the computing device 500 via transmission media or signals such as electrical, electromagnetic, or digital signals, conveyed via a communication medium such as a network and / or a wireless link. Various embodiments can further include receiving, sending or storing instructions and / or data implemented in accordance with the foregoing description upon a computer-accessible medium or via a communication medium. In general, a computer-accessible medium can include a storage medium or memory medium such as magnetic or optical media, e.g., disk or DVD / CD-ROM, volatile or non-volatile media such as RAM (e.g., SDRAM, DDR, RDRAM, SRAM, and the like), ROM, and the like.

[0084] The methods and processes described herein may be implemented in software, hardware, or a combination thereof, in different embodiments. In addition, the order of methods can be changed, and various elements can be added, reordered, combined, omitted or otherwise modified. All examples described herein are presented in a non-limiting manner. Various modifications and changes can be made as would be obvious to a person skilled in the art having benefit of this disclosure. Realizations in accordance with embodiments have been described in the context of particular embodiments. These embodiments are meant to be illustrative and not limiting. Many variations, modifications, additions, and improvements are possible. Accordingly, plural instances can be provided for components described herein as a single instance. Boundaries between various components, operations and data stores are somewhat arbitrary, and particular operations are illustrated in the context of specific illustrative configurations. Other allocations of functionality are envisioned and can fall within the scope of claims that follow. Structures and functionality presented as discrete components in the example configurations can be implemented as a combined structure or component. These and other variations, modifications, additions, and improvements can fall within the scope of embodiments as defined in the claims that follow.

[0085] In the foregoing description, numerous specific details, examples, and scenarios are set forth in order to provide a more thorough understanding of the present disclosure. It will be appreciated, however, that embodiments of the disclosure can be practiced without such specific details. Further, such examples and scenarios are provided for illustration, and are not intended to limit the disclosure in any way. Those of ordinary skill in the art, with the included descriptions, should be able to implement appropriate functionality without undue experimentation.

[0086] References in the specification to “an embodiment,” etc., indicate that the embodiment described can include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is believed to be within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly indicated.

[0087] Embodiments in accordance with the disclosure can be implemented in hardware, firmware, software, or any combination thereof. Embodiments can also be implemented as instructions stored using one or more machine-readable media, which may be read and executed by one or more processors. A machine-readable medium can include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device or a “virtual machine” running on one or more computing devices). For example, a machine-readable medium can include any suitable form of volatile or non-volatile memory.

[0088] In addition, the various operations, processes, and methods disclosed herein can be embodied in a machine-readable medium and / or a machine accessible medium / storage device compatible with a data processing system (e.g., a computer system), and can be performed in any order (e.g., including using means for achieving the various operations). Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. In some embodiments, the machine-readable medium can be a non-transitory form of machine- readable medium / storage device.

[0089] Modules, data structures, and the like defined herein are defined as such for ease of discussion and are not intended to imply that any specific implementation details are required. For example, any of the described modules and / or data structures can be combined or divided into sub-modules, sub-processes or other units of computer code or data as can be required by a particular design or implementation.

[0090] In the drawings, specific arrangements or orderings of schematic elements can be shown for ease of description. However, the specific ordering or arrangement of such elements is not meant to imply that a particular order or sequence of processing, or separation of processes, is required in all embodiments. In general, schematic elements used to represent instruction blocks or modules can be implemented using any suitable form of machine- readable instruction, and each such instruction can be implemented using any suitable programming language, library, application-programming interface (API), and / or other software development tools or frameworks. Similarly, schematic elements used to represent data or information can be implemented using any suitable electronic arrangement or data structure. Further, some connections, relationships or associations between elements can be simplified or not shown in the drawings so as not to obscure the disclosure.

[0091] 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 mapping an environment using signals transmitted from a transmitter, comprising: receiving a plurality of signals transmitted from the transmitter, where the plurality of signals comprise a plurality of propagation paths; extracting from each signal in the plurality of signals data representing a direction of departure; determining a transmitter location; determining a motion of at least one antenna of at least one receiver of the plurality of signals transmitted from the transmitter; generating a plurality of phasors sequences, where each phasor sequence represents a hypothesis based on motion of the at least one antenna and a direction of arrival estimate for each of the plurality of the received signals having a different propagation path; compensating the received signals, a plurality of local signals or correlation results for correlating the received signals with the local signals using the plurality of phasor sequences based on the plurality of hypotheses regarding the motion of the at least one antenna of the at least one receiver and the direction of arrival to generate a plurality of compensated correlation results; determining a preferred hypothesis in the plurality of hypotheses for each received signal that optimizes each correlation result in the plurality of compensated correlation results; identifying a direction of arrival for each of the plurality of received signals having a different propagation path using the determined hypothesis; determining a point of reflection from the direction of arrival of each received signal in the plurality of received signals having a different propagation path, a receiver location, the transmitter location, and the direction of departure; and processing the points of reflection to map at least one reflection surface in the environment.

2. The method of claim 1, wherein ray tracing is performed to identify a point of reflection.

3. The method of any of claims 1 and 2, wherein a point of reflection is defined as an intersection point of a vector in the direction of arrival and a vector in the direction of departure.

4. The method of claim 1, wherein the at least one receiver comprises two or more receivers and the points of reflection determined by each of the two or more receivers are added to map the at least one reflection surface in the environment.

5. The method of claim 1, wherein the preferred hypothesis is determined by at least one of a cost function that identifies the preferred hypotheses when the cost function reaches a minimum or when the cost function identifies a largest magnitude correlation value.

6. The method of claim 1, further comprising determining if the direction of arrival of a signal and the direction of departure of the signal are aligned to determine if the signal is a line of sight signal.

7. The method of any of claims 1 to 6, wherein determined line of sight signals are not directly used for surface mapping but are used to update mapping information such as to identify transient objects in the mapping.

8. An apparatus for mapping an environment using signals transmitted from a transmitter comprising: at least one processor; and a memory accessible to the at least one processor, the memory having stored therein at least one of programs or instructions executable by the processor to configure the apparatus to: receive a plurality of signals transmitted from the transmitter, where the plurality of signals comprise a plurality of propagation paths; extract from each signal in the plurality of signals data representing a direction of departure; determine a transmitter location;determine a motion of at least one antenna of at least one receiver of the plurality of signals transmitted from the transmitter; generate a plurality of phasors sequences, where each phasor sequence represents a hypothesis based on motion of the at least one antenna and a direction of arrival estimate for each of the plurality of the received signals having a different propagation path; compensate the received signals, a plurality of local signals or correlation results for correlating the received signals with the local signals using the plurality of phasor sequences based on the plurality of hypotheses regarding the motion of the at least one antenna of the at least one receiver and the direction of arrival to generate a plurality of compensated correlation results; determine a preferred hypothesis in the plurality of hypotheses for each received signal that optimizes each correlation result in the plurality of compensated correlation results; identify a direction of arrival for each of the plurality of received signals having a different propagation path using the determined hypothesis; determine a point of reflection from the direction of arrival of each received signal in the plurality of received signals having a different propagation path, a receiver location, the transmitter location, and the direction of departure; and process the points of reflection to map at least one reflection surface in the environment.

9. The apparatus of claim 8, wherein ray tracing is performed to identify a point of reflection.

10. The apparatus of any of claims 8 and 9, wherein a point of reflection is defined as an intersection point of a vector in the direction of arrival and a vector in the direction of departure.

11. The apparatus of claim 8, wherein the at least one receiver comprises two or more receivers and the points of reflection determined by each of the two or more receivers are added to map the at least one reflection surface in the environment.

12. The apparatus of claim 8, wherein the preferred hypothesis is determined by at least one of a cost function that identifies the preferred hypotheses when the cost function reaches a minimum or when the cost function identifies a largest magnitude correlation value.

13. The apparatus of claim 8, wherein the apparatus is further configured to determine if the direction of arrival of a signal and the direction of departure of the signal are aligned to determine if the signal is a line of sight signal.

14. The apparatus of any of claims 8 to 13, wherein determined line of sight signals are not directly used for surface mapping but are used to update mapping information such as to identify transient objects in the mapping.

15. A system for mapping an environment using signals transmitted from a transmitter comprising: at least one receiver comprising a respective antenna; a motion module; at least one transmitter; and an apparatus comprising at least one processor and at least one memory for storing programs and instructions that, when executed by the at least one processor, causes the system to perform operations comprising: receiving a plurality of signals transmitted from the transmitter, where the plurality of signals comprise a plurality of propagation paths; extracting from each signal in the plurality of signals data representing a direction of departure; determining a location of the transmitter; determining, using the motion module, a motion of the antenna of the at least one receiver; generating a plurality of phasors sequences, where each phasor sequence represents a hypothesis based on motion of the antenna of the at least one receiver and a direction of arrival estimate for each of the plurality of the received signals having a different propagation path;compensating the received signals, a plurality of local signals or correlation results for correlating the received signals with the local signals using the plurality of phasor sequences based on the plurality of hypotheses regarding the motion of the at least one antenna of the at least one receiver and the direction of arrival to generate a plurality of compensated correlation results; determining a preferred hypothesis in the plurality of hypotheses for each received signal that optimizes each correlation result in the plurality of compensated correlation results; identifying a direction of arrival for each of the plurality of received signals having a different propagation path using the determined hypothesis; determining a point of reflection from the direction of arrival of each received signal in the plurality of received signals having a different propagation path, a receiver location, the transmitter location, and the direction of departure; and processing the points of reflection to map at least one reflection surface in the environment.

16. The system of claim 15, wherein ray tracing is performed to identify a point of reflection.

17. The system of any of claims 15 and 16, wherein a point of reflection is defined as an intersection point of a vector in the direction of arrival and a vector in the direction of departure.

18. The system of claim 15, wherein the at least one receiver comprises two or more receivers and the points of reflection determined by each of the two or more receivers are added to map the at least one reflection surface in the environment.

19. The system of claim 15, wherein the preferred hypothesis is determined by at least one of a cost function that identifies the preferred hypotheses when the cost function reaches a minimum or when the cost function identifies a largest magnitude correlation value.

20. The system of claim 15, further comprising determining if the direction of arrival of a signal and the direction of departure of the signal are aligned to determine if the signal is a line of sight signal.

21. The system of any of claims 15 to 20, wherein determined line of sight signals are not directly used for surface mapping but are used to update mapping information such as to identify transient objects in the mapping.

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