Identifying beams of interest for position estimation

Disclosed are techniques for calculating timing metrics. A method comprises receiving, at a first node and from a second node, a set of beams, determining one or more times of arrival for each beam in the set of beams, identifying a positioning subset of beams based on the one or more times of arrival, wherein the positioning subset of beams is smaller than the set of beams and includes one or more beams from the set of beams, and calculating a timing metric based on the one or more times of arrival associated with the positioning subset of beams.

TECHNICAL FIELD

Various aspects described herein generally relate to wireless communication systems, and more particularly, to identifying beams of interest for position estimation.

INTRODUCTION

Some wireless communication networks, such as 5G, support operation at very high and even extremely-high frequency (EHF) bands, such as millimeter wave (mmW) frequency bands (generally, wavelengths of 1 mm to 10 mm, or 30 to 300 GHz). These extremely high frequencies may support very high throughput such as up to six gigabits per second (Gbps). One of the challenges for wireless communication at very high or extremely high frequencies, however, is that significant propagation loss may occur due to the high frequency. As the frequency increases, the wavelength decreases, and propagation losses may increase as well. At mmW frequency bands, the propagation loss may be severe. For example, the propagation loss may be on the order of 22 to 27 dB, relative to that observed in either the 2.4 GHz, or 5 GHz bands.

Propagation loss is also an issue in Multiple Input-Multiple Output (MIMO) and massive MIMO systems in any band. The term MIMO as used herein will generally refer to both MIMO and massive MIMO. MIMO is a method for multiplying the capacity of a radio link by using multiple transmit and receive antennas to exploit multipath propagation. Multipath propagation occurs because radio frequency (RF) signals not only travel by the shortest path between the transmitter and receiver, which may be a line of sight (LOS) path, but also over a number of other paths as they spread out from the transmitter and reflect from other objects such as hills, buildings, water, and the like on their way to the receiver. A transmitter in a MIMO system includes multiple antennas and takes advantage of multipath propagation by directing these antennas to each transmit the same RF signals on the same radio channel to a receiver. The receiver is also equipped with multiple antennas tuned to the radio channel that can detect the RF signals sent by the transmitter. As the RF signals arrive at the receiver (some RF signals may be delayed due to the multipath propagation), the receiver can combine them into a single RF signal. Because the transmitter sends each RF signal at a lower power level than it would send a single RF signal, propagation loss is also an issue in a MIMO system.

To address propagation loss issues in mmW band systems and MIMO systems, transmitters may use beamforming to extend RF signal coverage. In particular, transmit beamforming is a technique for emitting an RF signal in a specific direction, whereas receive beamforming is a technique used to increase receive sensitivity of RF signals that arrive at a receiver along a specific direction. Transmit beamforming and receive beamforming may be used in conjunction with each other or separately, and references to “beamforming” may herein refer to transmit beamforming, receive beamforming, or both. Traditionally, when a transmitter broadcasts an RF signal, it broadcasts the RF signal in nearly all directions determined by the fixed antenna pattern or radiation pattern of the antenna. With beamforming, the transmitter determines where a given receiver is located relative to the transmitter and projects a stronger downlink RF signal in that specific direction, thereby providing a faster (in terms of data rate) and stronger RF signal for the receiver. To change the directionality of the RF signal when transmitting, a transmitter can control the phase and relative amplitude of the RF signal broadcast by each antenna. For example, a transmitter may use an array of antennas (also referred to as a “phased array” or an “antenna array”) that creates a beam of RF waves that can be “steered” to point in different directions, without actually moving the antennas. Specifically, the RF current is fed to the individual antennas with the correct phase relationship so that the radio waves from the separate antennas add together to increase the radiation in a desired direction, while cancelling the radio waves from the separate antennas to suppress radiation in undesired directions.

To support position estimates in terrestrial wireless networks, a mobile device can be configured to measure and report the observed time difference of arrival (OTDOA) or reference signal timing difference (RSTD) between reference RF signals received from two or more network nodes (e.g., different base stations, or different transmission points (e.g., antennas) belonging to the same base station).

Where a transmitter uses beamforming to transmit RF signals, the beams of interest for data communication between the transmitter and receiver will be the beams carrying RF signals having the highest received signal strength (or highest received Signal to Noise plus Interference Ratio (SINR), for example, in the presence of a directional interfering signal). However, the receiver's ability to perform certain tasks may suffer when the receiver relies upon the beam with the highest received signal strength. For example, in a scenario where the beam with the highest received signal strength travels over a non-LOS (NLOS) path that is longer than the shortest path (i.e., a LOS path or a shortest NLOS path), the RF signals may arrive later than RF signal(s) received over the shortest path due to propagation delay. Accordingly, if the receiver is performing a task that requires precise timing measurements and the beam with the highest received signal strength is affected by longer propagation delay, then the beam with the highest received signal strength may not be optimal for the task at hand.

SUMMARY

Techniques for identifying beams of interest for position estimation are disclosed. According to an aspect, a method of identifying beams of interest for position estimation includes receiving, at a first node, a set of beams from a second node, determining one or more times of arrival for each beam in the set of beams, identifying a positioning subset of beams based on the one or more times of arrival for each beam in the set of beams, where the positioning subset of beams is smaller than the set of beams and includes one or more beams from the set of beams, and calculating a timing metric based on the one or more times of arrival associated with the positioning subset of beams.

According to further aspects, each beam in the set of beams is associated with a beam index and transmission at an angle of departure, where each beam in the set of beams has a different angle of departure and a different beam index from other beams in the set of beams. The positioning subset of beams may include one or more beams associated with earlier times of arrival than each of one or more remaining beams, where the one or more remaining beams are included in the set of beams and not included in the positioning subset of beams. Data relating to the times of arrival associated with each of the one or more remaining beams may be discarded. Further, the positioning subset of beams may include a beam associated with a cluster of multiple RF signals, and calculating the timing metric includes calculating the timing metric based on a time of arrival of an earliest-arriving RF signal in the cluster, an average time of arrival of the multiple RF signals in the cluster, a time of arrival of a highest-strength RF signal of the multiple RF signals in the cluster, or any combination thereof.

In another aspect, a signal strength for each beam in the set of beams may be determined, a data subset of beams based on the signal strengths may be identified, where the data subset of beams is smaller than the set of beams and includes at least one beam that is not included in the positioning subset of beams; and a data exchange via the data subset of beams may be requested and performed.

According to another aspect, the set of beams is a set of second-node beams, the positioning subset of beams is a positioning subset of second-node beams, and the timing metric is a second-node timing metric. At the first node, a set of third-node beams may be further received from a third node, one or more times of arrival for each beam in the set of third-node beams may be determined; and a positioning subset of third-node beams based on the one or more times of arrival may be identified, where the positioning subset of third-node beams is smaller than the set of third-node beams and includes one or more beams from the set of third-node beams, and a third-node timing metric calculated based on the one or more times of arrival associated with the positioning subset of third-node beams. Further, an Observed Time Difference Of Arrival (OTDOA) timing metric based on the second-node timing metric and the third-node timing metric may be calculated.

In a related aspect, the timing metric is a second-node timing metric, and a third-node timing metric may be received from a third node. Calculating the timing metric may then further include calculating an Observed Time Difference Of Arrival (OTDOA) metric equal to a difference between the second-node timing metric and the third-node timing metric.

An additional aspect provides that receiving the set of beams includes receiving a set of positioning beams, where each beam in the set of positioning beams carries a timing beacon signal. Another aspect provides that receiving the set of beams may include receiving a set of reference-signaling beams, and identifying the positioning subset of beams includes receiving Quasi-Co-Location (QCL) information, determining, based on the QCL information, whether the set of reference-signaling beams has a same spatial QCL as a set of positioning beams transmitted by the second node, and identifying the positioning subset of beams based on the times of arrival associated with the reference-signaling beams.

In another aspect, an apparatus for identifying beams of interest for position estimation includes at least one transceiver configured to receive, at a first node, a set of beams and from a second node, a set of beams, a memory configured to store data and/or instructions, and one or more processors, coupled to the memory and the at least one transceiver, that is configured to determine one or more times of arrival for each beam in the set of beams, identify a positioning subset of beams based on the one or more times of arrival for each beam in the set of beams, wherein the positioning subset of beams is smaller than the set of beams and includes one or more beams from the set of beams, and calculate a timing metric based on the one or more times of arrival associated with the positioning subset of beams. Further, each beam in the set of beams may be associated with a beam index, and transmission at an angle of departure, where each beam in the set of beams has a different beam index and a different angle of departure from other beams in the set of beams.

In a further aspect, the positioning subset of beams may include one or more beams that are associated with earlier times of arrival than each of one or more remaining beams, where the one or more remaining beams are included in the set of beams and not included in the positioning subset of beams. The one or more processors may be further configured to discard data relating to the times of arrival associated with each of the one or more remaining beams. The positioning subset of beams may also include a beam associated with a cluster of multiple RF signals, and to calculate the timing metric, the one or more processors may be further configured to calculate the timing metric based on a time of arrival of an earliest-arriving RF signal in the cluster, an average time of arrival of the multiple RF signals in the cluster, a time of arrival of a highest-strength RF signal of the multiple RF signals in the cluster, or any combination thereof.

In an aspect, the one or more processors is further configured to determine a signal strength for each beam in the set of beams, identify a data subset of beams based on the signal strengths, wherein the data subset of beams is smaller than the set of beams and includes at least one beam that is not included in the positioning subset of beams, and exchange data via the data subset of beams and/or requesting a data exchange via the data subset of beams.

In a further aspect, the set of beams is a set of second-node beams, the positioning subset of beams is a positioning subset of second-node beams, and the timing metric is a second-node timing metric, where the at least one transceiver is further configured to receive, at the first node and from a third node, a set of third-node beams, and the one or more processors is further configured to determine a time of arrival for each beam in the set of third-node beams, identify a positioning subset of third-node beams based on the times of arrival, where the positioning subset of third-node beams is smaller than the set of third-node beams and includes one or more beams from the set of third-node beams, and calculate a third-node timing metric based on one or more times of arrival respectively associated with each beam in the positioning subset of third-node beams.

According to other aspect, the one or more processors may be further configured to calculate an Observed Time Difference Of Arrival (OTDOA) timing metric based on the second-node timing metric and the third-node timing metric.

In an aspect, the timing metric is a second-node timing metric, and the at least one transceiver is further configured to receive a third-node timing metric from a third node, and the one or more processors is further configured to calculate the timing metric and an Observed Time Difference Of Arrival (OTDOA) metric equal to a difference between the second-node timing metric and the third-node timing metric.

In an aspect, to receive the set of beams, the at least one transceiver is configured to receive a set of positioning beams, where each beam in the set of positioning beams carries a timing beacon signal. In another aspect, to receive the set of beams, the at least one transceiver may be configured to receive a set of reference-signaling beams. To identify the positioning subset of beams, the at least one transceiver is configured to receive Quasi-Co-Location (QCL) information, and the one or more processors is configured to determine, based on the QCL information, whether the set of reference-signaling beams has a same spatial QCL as a set of positioning beams transmitted by the second node, and identify the positioning subset of beams based on the times of arrival associated with the reference-signaling beams.

DETAILED DESCRIPTION

Various aspects described herein generally relate to wireless communication systems, and more particularly, to identifying beams of interest for position estimation. These and other aspects are disclosed in the following description and related drawings to show specific examples relating to exemplary aspects. Alternate aspects will be apparent to those skilled in the pertinent art upon reading this disclosure, and may be constructed and practiced without departing from the scope or spirit of the disclosure. Additionally, well-known elements will not be described in detail or may be omitted so as to not obscure the relevant details of the aspects disclosed herein.

The terminology used herein describes particular aspects only and should not be construed to limit any aspects disclosed herein. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Those skilled in the art will further understand that the terms “comprises,” “comprising,” “includes,” and/or “including,” as used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Further, various aspects may be described in terms of sequences of actions to be performed by, for example, elements of a computing device. Those skilled in the art will recognize that various actions described herein can be performed by specific circuits (e.g., an application specific integrated circuit (ASIC)), by program instructions being executed by one or more processors, or by a combination of both. Additionally, these sequences of actions described herein can be considered to be embodied entirely within any form of non-transitory computer-readable medium having stored thereon a corresponding set of computer instructions that upon execution would cause an associated processor to perform the functionality described herein. Thus, the various aspects described herein may be embodied in a number of different forms, all of which have been contemplated to be within the scope of the claimed subject matter. In addition, for each of the aspects described herein, the corresponding form of any such aspects may be described herein as, for example, “logic configured to” and/or other structural components configured to perform the described action.

As used herein, the terms “user equipment” (or “UE”), “user device,” “user terminal,” “client device,” “communication device,” “wireless device,” “wireless communications device,” “handheld device,” “mobile device,” “mobile terminal,” “mobile station,” “handset,” “access terminal,” “subscriber device,” “subscriber terminal,” “subscriber station,” “terminal,” and variants thereof may interchangeably refer to any suitable mobile or stationary device that can receive wireless communication and/or navigation signals. These terms are also intended to include devices which communicate with another device that can receive wireless communication and/or navigation signals such as by short-range wireless, infrared, wireline connection, or other connection, regardless of whether satellite signal reception, assistance data reception, and/or position-related processing occurs at the device or at the other device. In addition, these terms are intended to include all devices, including wireless and wireline communication devices, which can communicate with a core network via a radio access network (RAN), and through the core network the UEs can be connected with external networks such as the Internet and with other UEs. Of course, other mechanisms of connecting to the core network and/or the Internet are also possible for the UEs, such as over a wired access network, a wireless local area network (WLAN) (e.g., based on IEEE 802.11, etc.) and so on. UEs can be embodied by any of a number of types of devices including but not limited to printed circuit (PC) cards, compact flash devices, external or internal modems, wireless or wireline phones, smartphones, tablets, tracking devices, asset tags, and so on. A communication link through which UEs can send signals to a RAN is called an uplink channel (e.g., a reverse traffic channel, a reverse control channel, an access channel, etc.). A communication link through which the RAN can send signals to UEs is called a downlink or forward link channel (e.g., a paging channel, a control channel, a broadcast channel, a forward traffic channel, etc.). As used herein the term traffic channel (TCH) can refer to either an uplink/reverse or downlink/forward traffic channel.

In accordance with various aspects,FIG. 1illustrates an exemplary wireless communications system100. The wireless communications system100(which may also be referred to as a wireless wide area network (WWAN)) may include various base stations102and various UEs104. The base stations102may include macro cells (high power cellular base stations) and/or small cells (low power cellular base stations), wherein the macro cells may include Evolved NodeBs (eNBs), where the wireless communications system100corresponds to an LTE network, or gNodeBs (gNBs), where the wireless communications system100corresponds to a 5G network or a combination of both, and the small cells may include femtocells, picocells, microcells, etc.

The base stations102may collectively form a Radio Access Network (RAN) and interface with an Evolved Packet Core (EPC) or Next Generation Core (NGC) through backhaul links134. In addition to other functions, the base stations102may perform functions that relate to one or more of transferring user data, radio channel ciphering and deciphering, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection setup and release, load balancing, distribution for non-access stratum (NAS) messages, NAS node selection, synchronization, RAN sharing, multimedia broadcast multicast service (MBMS), subscriber and equipment trace, RAN information management (RIM), paging, positioning, and delivery of warning messages. The base stations102may communicate with each other directly or indirectly (e.g., through the EPC/NGC) over backhaul links134, which may be wired or wireless.

The base stations102may wirelessly communicate with the UEs104. Each of the base stations102may provide communication coverage for a respective geographic coverage area110. In an aspect, although not shown inFIG. 1, geographic coverage areas110may be subdivided into a plurality of cells (e.g., three), or sectors, each cell corresponding to a single antenna or array of antennas of a base station102. As used herein, the term “cell” or “sector” may correspond to one of a plurality of cells of a base station102, or to the base station102itself, depending on the context.

While neighboring macro cell geographic coverage areas110may partially overlap (e.g., in a handover region), some of the geographic coverage areas110may be substantially overlapped by a larger geographic coverage area110. For example, the small cell102′ may have a geographic coverage area110′ that substantially overlaps with the geographic coverage area110of one or more macro base stations102. A network that includes both small cell and macro cells may be known as a heterogeneous network. A heterogeneous network may also include Home eNBs (HeNBs), which may provide service to a restricted group known as a closed subscriber group (CSG). The communication links120between the base stations102and the UEs104may include uplink (UL) (also referred to as reverse link) transmissions from a UE104to a base station102and/or downlink (DL) (also referred to as forward link) transmissions from a base station102to a UE104. The communication links120may use MIMO antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity. The communication links may be through one or more carriers. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or less carriers may be allocated for DL than for UL).

The small cell102′ may operate in a licensed and/or an unlicensed frequency spectrum. When operating in an unlicensed frequency spectrum, the small cell102′ may employ LTE or 5G technology and use the same 5 GHz unlicensed frequency spectrum as used by the WLAN AP150. The small cell102′, employing LTE/5G in an unlicensed frequency spectrum, may boost coverage to and/or increase capacity of the access network. LTE in an unlicensed spectrum may be referred to as LTE-unlicensed (LTE-U), licensed assisted access (LAA), or MulteFire.

According to various aspects,FIG. 2Aillustrates an example wireless network structure200. For example, a Next Generation Core (NGC)210can be viewed functionally as control plane functions214(e.g., UE registration, authentication, network access, gateway selection, etc.) and user plane functions212, (e.g., UE gateway function, access to data networks, IP routing, etc.) which operate cooperatively to form the core network. User plane interface (NG-U)213and control plane interface (NG-C)215connect the gNB222to the NGC210and specifically to the control plane functions214and user plane functions212. In an additional configuration, an eNB224may also be connected to the NGC210via NG-C215to the control plane functions214and NG-U213to user plane functions212. Further, eNB224may directly communicate with gNB222via a backhaul connection223. Accordingly, in some configurations, the New RAN220may only have one or more gNBs222, while other configurations include one or more of both eNBs224and gNBs222. Either gNB222or eNB224may communicate with UEs240(e.g., any of the UEs depicted inFIG. 1, such as UEs104, UE182, UE190, etc.). Another optional aspect may include Location Server230which may be in communication with the NGC210to provide location assistance for UEs240. The location server230can be implemented as a plurality of structurally separate servers, or alternately may each correspond to a single server. The location server230can be configured to support one or more location services for UEs240that can connect to the location server230via the core network, NGC210, and/or via the Internet (not illustrated). Further, the location server230may be integrated into a component of the core network, or alternatively may be external to the core network.

According to various aspects,FIG. 2Billustrates another example wireless network structure250. For example, Evolved Packet Core (EPC)260can be viewed functionally as control plane functions, Mobility Management Entity (MME)264and user plane functions, Packet Data Network Gateway/Serving Gateway (P/SGW),262, which operate cooperatively to form the core network. S1 user plane interface (S1-U)263and S1 control plane interface (S1-MME)265connect the eNB224to the EPC260and specifically to MME264and P/SGW262. In an additional configuration, a gNB222may also be connected to the EPC260via S1-MME265to MME264and S1-U263to P/SGW262. Further, eNB224may directly communicate to gNB222via the backhaul connection223, with or without gNB direct connectivity to the EPC. Accordingly, in some configurations, the New RAN220may only have one or more gNBs222, while other configurations include one or more of both eNBs224and gNBs222. Either gNB222or eNB224may communicate with UEs240(e.g., any of the UEs depicted inFIG. 1, such as UEs104, UE182, UE190, etc.). Another optional aspect may include Location Server230which may be in communication with the EPC260to provide location assistance for UEs240. The location server230can be implemented as a plurality of structurally separate servers, or alternately may each correspond to a single server.

The location server230can be configured to support one or more location services for UEs240that can connect to the location server230via the core network, EPC260, and/or via the Internet (not illustrated).

According to various aspects,FIG. 3illustrates an exemplary base station310(e.g., an eNB, a gNB, a small cell AP, a WLAN AP, etc.) in communication with an exemplary UE350in a wireless network. In the DL, IP packets from the core network (NGC210/EPC260) may be provided to a controller/processor375. The controller/processor375implements functionality for a radio resource control (RRC) layer, a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a medium access control (MAC) layer. The controller/processor375provides RRC layer functionality associated with broadcasting of system information (e.g., MIB, SIBs), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter-RAT mobility, and measurement configuration for UE measurement reporting; PDCP layer functionality associated with header compression/decompression, security (ciphering, deciphering, integrity protection, integrity verification), and handover support functions; RLC layer functionality associated with the transfer of upper layer packet data units (PDUs), error correction through ARQ, concatenation, segmentation, and reassembly of RLC service data units (SDUs), re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, scheduling information reporting, error correction, priority handling, and logical channel prioritization.

The controller/processor359can be associated with a memory360that stores program codes and data. The memory360may be referred to as a computer-readable medium. In the UL, the controller/processor359provides de-multiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, and control signal processing to recover IP packets from the core network. The controller/processor359is also responsible for error detection.

The controller/processor375can be associated with a memory376that stores program codes and data. The memory376may be referred to as a computer-readable medium. In the UL, the controller/processor375provides de-multiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover IP packets from the UE350. IP packets from the controller/processor375may be provided to the core network. The controller/processor375is also responsible for error detection.

FIG. 4illustrates an exemplary wireless communications system400according to various aspects of the disclosure. In the example ofFIG. 4, a UE404, which may correspond to any of the UEs described above with respect toFIG. 1(e.g., UEs104, UE182, UE190, etc.), is attempting to calculate an estimate of its position, or assist another entity (e.g., a base station or core network component, another UE, a location server, a third party application, etc.) to calculate an estimate of its position. The UE404may communicate wirelessly with a plurality of base stations402a-d(collectively, base stations402), which may correspond to any combination of base stations102or180and/or WLAN AP150inFIG. 1, using RF signals and standardized protocols for the modulation of the RF signals and the exchange of information packets. By extracting different types of information from the exchanged RF signals, and utilizing the layout of the wireless communications system400(i.e., the base stations' locations, geometry, etc.) the UE404may determine its position, or assist in the determination of its position, in a predefined reference coordinate system. In an aspect, the UE404may specify its position using a two-dimensional coordinate system; however, the aspects disclosed herein are not so limited, and may also be applicable to determining positions using a three-dimensional coordinate system, if the extra dimension is desired. Additionally, whileFIG. 4illustrates one UE404and four base stations402, as will be appreciated, there may be more UEs404and more or fewer base stations402.

To support position estimates, the base stations402may be configured to broadcast reference RF signals (e.g., Positioning Reference Signals (PRS), Cell-specific Reference Signals (CRS), Channel State Information Reference Signals (CSI-RS), synchronization signals, etc.) to UEs404in their coverage area to enable a UE404to measure reference RF signal timing differences (e.g., OTDOA or RSTD) between pairs of network nodes and/or to identify the beam that best excites the LOS or shortest radio path between the UE404and the transmitting base stations402. Identifying the LOS/shortest path beam(s) is of interest not only because these beams can subsequently be used for OTDOA measurements between a pair of base stations402, but also because identifying these beams can directly provide some positioning information based on the beam direction. Moreover, these beams can subsequently be used for other position estimation methods that require precise ToA, such as round-trip time estimation based methods.

As used herein, a “network node” may be a base station402, a cell of a base station402, a remote radio head, an antenna of a base station402, where the locations of the antennas of a base station402are distinct from the location of the base station402itself, or any other network entity capable of transmitting reference signals. Further, as used herein, a “node” may refer to either a network node or a UE.

A location server (e.g., location server230) may send assistance data to the UE404that includes an identification of one or more neighbor cells of base stations402and configuration information for reference RF signals transmitted by each neighbor cell. Alternatively, the assistance data can originate directly from the base stations themselves402(e.g., in periodically broadcasted overhead messages, etc.). Alternatively, the UE404can detect neighbor cells of base stations402itself without the use of assistance data. The UE404(e.g., based in part on the assistance data, if provided) can measure and (optionally) report the OTDOA from individual network nodes and/or RSTDs between reference RF signals received from pairs of network nodes. Using these measurements and the known locations of the measured network nodes (i.e., the base station(s)402or antenna(s) that transmitted the reference RF signals that the UE404measured), the UE404or the location server can determine the distance between the UE404and the measured network nodes and thereby calculate the location of the UE404.

The term “position estimate” is used herein to refer to an estimate of a position for a UE404, which may be geographic (e.g., may comprise a latitude, longitude, and possibly altitude) or civic (e.g., may comprise a street address, building designation, or precise point or area within or nearby to a building or street address, such as a particular entrance to a building, a particular room or suite in a building, or a landmark such as a town square). A position estimate may also be referred to as a “location,” a “position,” a “fix,” a “position fix,” a “location fix,” a “location estimate,” a “fix estimate,” or by some other term. The means of obtaining a location estimate may be referred to generically as “positioning,” “locating,” or “position fixing.” A particular solution for obtaining a position estimate may be referred to as a “position solution.” A particular method for obtaining a position estimate as part of a position solution may be referred to as a “position method” or as a “positioning method.”

The term “base station” may refer to a single physical transmission point or to multiple physical transmission points that may or may not be co-located. For example, where the term “base station” refers to a single physical transmission point, the physical transmission point may be an antenna of the base station (e.g., base station402) corresponding to a cell of the base station. Where the term “base station” refers to multiple co-located physical transmission points, the physical transmission points may be an array of antennas (e.g., as in a MIMO system or where the base station employs beamforming) of the base station. Where the term “base station” refers to multiple non-co-located physical transmission points, the physical transmission points may be a Distributed Antenna System (DAS) (a network of spatially separated antennas connected to a common source via a transport medium) or a Remote Radio Head (RRH) (a remote base station connected to a serving base station). Alternatively, the non-co-located physical transmission points may be the serving base station receiving the measurement report from the UE (e.g., UE404) and a neighbor base station whose reference RF signals the UE is measuring. Thus,FIG. 4illustrates an aspect in which base stations402aand402bform a DAS/RRH420. For example, the base station402amay be the serving base station of the UE404and the base station402bmay be a neighbor base station of the UE404. As such, the base station402bmay be the RRH of the base station402a. The base stations402aand402bmay communicate with each other over a wired or wireless link422.

To accurately determine the position of the UE404using the OTDOAs and/or RSTDs between RF signals received from pairs of network nodes, the UE404needs to measure the reference RF signals received over the LOS path (or the shortest NLOS path where an LOS path is not available), between the UE404and a network node (e.g., base station402, antenna). However, RF signals travel not only by the LOS/shortest path between the transmitter and receiver, but also over a number of other paths as the RF signals spread out from the transmitter and reflect from other objects such as hills, buildings, water, and the like on their way to the receiver. Thus,FIG. 4illustrates a number of LOS paths410and a number of NLOS paths412between the base stations402and the UE404. Specifically,FIG. 4illustrates base station402atransmitting over an LOS path410aand an NLOS path412a, base station402btransmitting over an LOS path410band two NLOS paths412b, base station402ctransmitting over an LOS path410cand an NLOS path412c, and base station402dtransmitting over two NLOS paths412d. As illustrated inFIG. 4, each NLOS path412reflects from some object430(e.g., a building). As will be appreciated, each LOS path410and NLOS path412transmitted by a base station402may be transmitted by different antennas of the base station402(e.g., as in a MIMO system), or may be transmitted by the same antenna of a base station402(thereby illustrating the propagation of an RF signal). Further, as used herein, the term “LOS path” refers to the shortest path between a transmitter and receiver, and may not be an actual LOS path, but rather, the shortest NLOS path.

In an aspect, one or more of base stations402may be configured to use beamforming to transmit RF signals. In that case, some of the available beams may focus the transmitted RF signal along the LOS paths410(e.g., the beams produce highest antenna gain along the LOS paths) while other available beams may focus the transmitted RF signal along the NLOS paths412. A beam that has high gain along a certain path and thus focuses the RF signal along that path may still have some RF signal propagating along other paths; the strength of that RF signal naturally depends on the beam gain along those other paths. An “RF signal” comprises an electromagnetic wave that transports information through the space from the transmitter to the receiver. As used herein, a transmitter may transmit a single “RF signal” or multiple “RF signals” to a receiver. However, as described further below, the receiver may receive multiple “RF signals” corresponding to each transmitted RF signal due to the propagation characteristics of RF signals through multipath channels.

Where a base station402uses beamforming to transmit RF signals, the beams of interest for data communication between the base station402and the UE404will be the beams carrying RF signals that arrive at UE404with the highest signal strength (as indicated by, e.g., the Received Signal Received Power (RSRP) or SINR in the presence of a directional interfering signal), whereas the beams of interest for position estimation will be the beams carrying RF signals that excite the shortest path or LOS path (e.g., an LOS path410). In some frequency bands and for antenna systems typically used, these will be the same beams. However, in other frequency bands, such as mmW, where typically a large number of antenna elements can be used to create narrow transmit beams, they may not be the same beams. As described below with reference toFIG. 5, in some cases, the signal strength of RF signals on the LOS path410may be weaker (e.g., due to obstructions) than the signal strength of RF signals on an NLOS path412, over which the RF signals arrive later due to propagation delay.

FIG. 5illustrates an exemplary wireless communications system500according to various aspects of the disclosure. In the example ofFIG. 5, a UE504, which may correspond to UE404inFIG. 4, is attempting to calculate an estimate of its position, or to assist another entity (e.g., a base station or core network component, another UE, a location server, a third-party application, etc.) to calculate an estimate of its position. The UE504may communicate wirelessly with a base station502, which may correspond to one of base stations402inFIG. 4, using RF signals and standardized protocols for the modulation of the RF signals and the exchange of information packets.

As illustrated inFIG. 5, the base station502is utilizing beamforming to transmit a plurality of beams511-515of RF signals. Each beam511-515may be formed and transmitted by an array of antennas of the base station502. AlthoughFIG. 5illustrates a base station502transmitting five beams, it will be appreciated that (i) there may be more or fewer than five beams, (ii) beam shapes such as peak gain, width, and side-lobe gains may differ amongst the transmitted beams, and (iii) some of the beams may be transmitted by a different base station.

A beam index may be assigned to each of the plurality of beams511-515for purposes of distinguishing RF signals associated with one beam from RF signals associated with another beam. Further, the RF signals associated with a particular beam of the plurality of beams511-515may carry a beam index indicator. A beam index may also be derived from the time of transmission, e.g., frame, slot, and/or OFDM symbol number, of the RF signal. The beam index indicator may be, for example, a three-bit field for uniquely distinguishing up to eight beams. If two different RF signals having different beam indices are received, the different beam indices would indicate that the RF signals were transmitted using different beams. If two different RF signals share a common beam index, the common beam index would indicate that the different RF signals are transmitted using the same beam. Another way to describe that two RF signals are transmitted using the same beam is to say that the antenna port(s) used for the transmission of first RF signal is (are) spatially quasi-collocated with the antenna port(s) used for the transmission of the second RF signal.

In the example ofFIG. 5, the UE504receives an NLOS data stream523of RF signals transmitted on beam513and an LOS data stream524of RF signals transmitted on beam514. AlthoughFIG. 5illustrates the NLOS data stream523and the LOS data stream524as single lines (dashed and solid, respectively), as will be appreciated, the NLOS data stream523and the LOS data stream524may each comprise multiple rays (i.e., a “cluster”) by the time they reach the UE504due, for example, to the propagation characteristics of RF signals through multipath channels. That is, a cluster of RF signals may be formed when an electromagnetic wave is reflected from multiple surfaces of an object, and the resulting reflections arrive at the receiver (e.g., UE504) from roughly the same angle, each travelling a few wavelengths (e.g., centimeters) more or less than others. Such a “cluster” of received RF signals will generally correspond with a single transmitted RF signal.

In the example ofFIG. 5, the NLOS data stream523is not originally directed at the UE504. However, as will be appreciated, it could be, as are the RF signals on the NLOS paths412depicted inFIG. 4. The NLOS data stream523is reflected from a reflector540(e.g., a building) and reaches the UE504without further obstruction, and may therefore still be a relatively strong RF signal. By contrast, the LOS data stream524is directed at the UE504but passes through an obstruction530(e.g., vegetation, a building, a hill, a disruptive environment such as clouds, or smoke, etc.), which may significantly degrade the RF signal. As will be appreciated, although the LOS data stream524is weaker than the NLOS data stream523, the LOS data stream524will nonetheless arrive at the UE504before the NLOS data stream523because it follows a shorter path from the base station502to the UE504.

As noted above, the beam of interest for data communication between a base station (e.g., base station502) and a UE (e.g., UE504) is the beam carrying RF signals that arrives at the UE with the highest signal strength (e.g., highest RSRP or SINR). By contrast, the beam of interest for position estimation is the beam carrying RF signals that excite the LOS path and that has the highest gain along the LOS path amongst all other beams (e.g., beam514). That is, even if beam513(the NLOS beam) were to weakly excite the LOS path (due to the propagation characteristics of RF signals, and even though not being focused along the LOS path), that weak signal, if any, of the LOS path of beam513may not be as reliably detectable compared to that from beam514, thus contributing to errors in performing a positioning measurement.

While the beam of interest for data communication and the beam of interest for position estimation may be the same beams for some frequency bands, for other frequency bands, such as mmW, they may not be the same beams. As such, referring toFIG. 5, where the UE504is engaged in a data communication session with the base station502(e.g., where the base station502is the serving base station for the UE504) and not simply attempting to measure reference RF signals transmitted by the base station502, the beam of interest for the data communication session may be the beam513, as it is carrying the unobstructed NLOS data stream523. The beam of interest for position estimation, however, would be the beam514, as it carries the strongest LOS data stream524, despite being obstructed.

FIG. 6Ais a graph600A showing the RF channel response at a receiver (e.g., UE504) over time according to aspects of the disclosure. Under the channel illustrated inFIG. 6A, the receiver receives a first cluster of two RF signals on channel taps at time T1, a second cluster of five RF signals on channel taps at time T2, a third cluster of five RF signals on channel taps at time T3, and a fourth cluster of four RF signals on channel taps at time T4. In the example ofFIG. 6A, because the first cluster of RF signals at time T1arrives first, it is presumed to be the LOS data stream (i.e., the data stream arriving over the LOS or the shortest path), and may correspond to the LOS data stream524. The third cluster at time T3comprises the strongest RF signals, and may correspond to the NLOS data stream523. Seen from the transmitter's side, each cluster of received RF signals may comprise the portion of an RF signal transmitted at a different angle, and thus each cluster may be said to have a different angle of departure (AoD) from the transmitter.

FIG. 6Billustrates this separation of clusters in an AoD spread600B. The RF signal transmitted in AoD range602amay correspond to one cluster (e.g., “Cluster1”) inFIG. 6A, and the RF signal transmitted in AoD range602bmay correspond to a different cluster (e.g., “Cluster3”) inFIG. 6A. Note that although AoD ranges of the two clusters depicted inFIG. 6Bare spatially isolated, AoD ranges of some clusters may also partially overlap even though the clusters are separated in time. For example, this may arise when two separate buildings at a same AoD from the transmitter reflect the signal towards the receiver. Note that althoughFIG. 6Aillustrates clusters of two to five channel taps, as will be appreciated, the clusters may have more or fewer than the illustrated number of channel taps.

As in the example ofFIG. 5, the base station may utilize beamforming to transmit a plurality of beams of RF signals such that one of the beams (e.g., beam514) is directed at the AoD range602aof the first cluster of RF signals, and a different beam (e.g., beam513) is directed at the AoD range602bof the third cluster of RF signals. The signal strength of clusters in post-beamforming channel response (i.e., the channel response when the transmitted RF signal is beamformed instead of omnidirectional) will be scaled by the beam gain along the AoD of the clusters. In that case, the beam of interest for positioning would be the beam directed at the AoD of the first cluster of RF signals, as they arrive first, and the beam of interest for data communications may be the beam directed at the AoD of the third cluster of RF signals, as they are the strongest.

In general, when transmitting an RF signal, the transmitter does not know what path it will follow to the receiver (e.g., UE504) or at what time it will arrive at the receiver, and therefore transmits the RF signal on different antenna ports with an equal amount of energy. Alternatively, the transmitter may beamform the RF signal in different directions over multiple transmission occasions and obtain measurement feedback from the receiver to explicitly or implicitly determine radio paths.

Note that although the techniques disclosed herein have generally been described in terms of transmissions from a base station to a UE, as will be appreciated, they are equally applicable to transmissions from a UE to a base station where the UE is capable of MIMO operation and/or beamforming. Also, while beamforming is generally described above in context with transmit beamforming, receive beamforming may also be used in conjunction with the above-noted transmit beamforming in certain embodiments.

As discussed above, in some frequency bands, the shortest path (which, as noted above, may be a LOS path or the shortest NLOS path) may be weaker than an alternative longer (NLOS) path (over which the RF signal arrives later due to propagation delay). Thus, where a transmitter uses beamforming to transmit RF signals, the beam of interest for data communication—the beam carrying the strongest RF signals—may be different from the beam of interest for position estimation—the beam carrying the RF signals that excite the shortest detectable path. As such, it would be beneficial for the receiver to identify and report the beam of interest for position estimation to the transmitter to enable the transmitter to subsequently modify the set of transmitted beams to assist the receiver to perform a position estimation.

FIG. 7illustrates an exemplary method700, according to various aspects. The method700depicted inFIG. 7may be performed by, for example, any or all of the UEs, base stations, or access points depicted inFIGS. 1-5. For example, the method700may be performed by any of the base stations102, UEs104, WLAN AP150, WLAN STA152, mmW base station180, or UE182depicted inFIG. 1, the UE104, gNB222, or eNB224depicted inFIG. 2A, the UE240, gNB222, or eNB224depicted inFIG. 2B, the base station310or UE350depicted inFIG. 3, any of the base stations402or the UE404depicted inFIG. 4, the base station502or the UE504depicted inFIG. 5, or any component analogous thereto.

At710of the method700, a set of beams is received. The receiving may be performed by, for example, one or more transceiver/antenna combinations analogous to the receiver354RX and/or antenna352depicted inFIG. 3. Accordingly, the receiver354RX and/or antenna352may constitute means for receiving a set of beams.

At720of the method700, one or more times of arrival are determined for each beam in the set of beams received at710. The determining may be performed by, for example, the controller/processor359and/or the memory360depicted inFIG. 3. Accordingly, the controller/processor359and/or the memory360may constitute means for determining a time of arrival for each beam in the set of beams.

At730of the method700, a positioning subset of beams is identified, based on the one or more times of arrival for each beam determined at720. For example, the positioning subset of beams may comprise a single beam with the earliest time of arrival amongst all beams in the set of beams received at710. As used herein, the phrase “based on” should be construed as “based at least in part on” rather than, for example, “based solely on,” unless the context clearly indicates the latter. The identifying may be performed by, for example, the controller/processor359and/or the memory360depicted inFIG. 3. Accordingly, the controller/processor359and/or the memory360may constitute means for identifying a positioning subset of beams based on the times of arrival.

At740of the method700, a timing metric is calculated, based on the one or more times of arrival associated with the positioning subset of beams. The calculating may be performed by, for example, the controller/processor359and/or the memory360depicted inFIG. 3. Accordingly, the controller/processor359and/or the memory360may constitute means for determining a timing metric based on one or more times of arrival associated with the positioning subset of beams.

As noted above, the method700may be used to identify a beam that is optimal for positioning measurements. In some implementations, the method700may be implemented in combination with a method for identifying a beam that is optimal for purposes of data exchange. The method for identifying a beam that is optimal for purposes of data exchange may comprise (i) determining a signal strength for each beam in the set of beams, (ii) identifying a data subset of beams (i.e., a subset of the beams for data exchange) based on the signal strengths, wherein the data subset of beams is smaller than the set of beams and includes one or more beams from the set of beams, and then (iii) exchanging data via the data subset of beams and/or requesting a data exchange via the data subset of beams. If the method700and the method just described for identifying a beam that is optimal for purposes of data exchange are both implemented, then the node may use one beam for positioning measurements and a different beam for data exchange. For example, the data subset of beams may include at least one beam that is not included in the positioning subset of beams.

FIG. 8illustrates an exemplary signal flow diagram, according to various aspects.FIG. 8depicts a first node801, a second node802, and a third node803. The first node801may be analogous to any of the UEs, base stations, eNBs, or access points depicted inFIGS. 1-5. Like the first node801, the second node802and the third node803may be analogous to any of the UEs, base stations, eNBs, or access points depicted inFIGS. 1-5. However, it will be understood that the first node801, second node802, and third node803are different nodes that are configured to communicate with each other.

At810, the second node802transmits a set of second-node beams, including a first beam811, a second beam812, and a third beam813. The second node802may transmit the beams811-813at different AoDs, as illustrated above inFIGS. 5 and 6B. For illustrative purposes, three beams are depicted inFIG. 8, but it will be understood that any number of beams may be transmitted at810. Moreover, the set of beams may include one or more spatially-multiplexed beams analogous to the beamforming184depicted inFIG. 1or the beams511-515depicted inFIG. 5. The set of beams may be transmitted simultaneously and/or intermittently.

In some implementations, the set of beams may be a set of positioning beams. Each positioning beam may carry a timing beacon signal. In other implementations, the set of beams may be a set of reference-signaling beams, for example, Primary Synchronization Signal (PSS), Secondary Synchronization Signal (SSS), Physical Broadcast Channel (PBCH) blocks, Channel State Information Reference Signal (CSI-RS), etc. The second node802may transmit both the set of positioning beams and the set of reference-signaling beams. As will be discussed in greater detail below, in the event that the set of positioning beams and the set of reference-signaling beams are spatially Quasi-Co-Located (QCL), then the first node801may use the set of reference-signaling beams as a proxy for the set of positioning beams, and use the reference-signaling beams to short-list the relevant positioning beams for reception. In particular, if certain reference-signaling beams are undetectable or too weak, or their times of arrival are too late, then there may be no need for the first node to receive the corresponding positioning beams or calculate times of arrival of the corresponding positioning beams. The QCL information may be provided to the first node801by the second node802or any other suitable node.

At814, the first node801receives the set of second-node beams811-813. As discussed previously, each beam in the set of second-node beams may travel a different path from the second node802to the first node801. For example, the first beam811and the third beam813may travel NLOS paths, whereas the second beam812may travel a LOS path.

At820, the first node801determines one or more times of arrival for each beam in the set of second-node beams. For example, the first beam811may have a first range of times of arrival, the second beam812may have a second range of times of arrival, and the third beam813may have a third range of times of arrival.

The times of arrival for each beam may be determined at820in any suitable manner. For example, if the beam is received as a single RF signal, then the time of arrival of the beam may be calculated as being equal to the time of arrival of the single RF signal. If the beam is received as a cluster of multiple RF signals (for example, multiple RF signals having a common beam index, as indicated by the beam index indicator), then the time of arrival of the beam may be calculated in any of a number ways. For example, the time of arrival of the beam may be set equal to a time of arrival of the earliest-arriving RF signal in the cluster, an average time of arrival across each of the multiple RF signals in the cluster, a time of arrival of the highest-strength RF signal from among the multiple RF signals in the cluster, or any combination thereof. In some implementations, the first node801may discard times of arrival associated with RF signals having a signal strength that does not exceed a signal strength threshold, and calculate the time of arrival of the beam based solely on an RF signal (or RF signals) that do exceed the signal strength threshold. The first node801may estimate the channel response from the received signal and take as time of arrival the earlier detected channel tap. It will be appreciated that other determinations at820of the times of arrival for each beam are possible.

At830, the first node801identifies a positioning subset of second-node beams based on the one or more times of arrival determined at820. The positioning subset of second-node beams may include one or more beams from the set of second-node beams received at814, but may omit one or more other beams from the set of second-node beams received at814. For example, the second beam812may have earlier times of arrival than the first beam811and the third beam813. Accordingly, the second beam812may be included in the position subset of second-node beams identified at830, whereas the first beam811and the third beam813may be omitted from the position subset of second-node beams.

If the first node801is a MIMO node that includes multiple transceivers, the first node801may perform reception beamforming with respect to the positioning subset of beams identified at830. In particular, once the first node801identifies a beam of interest for positioning purposes, the first node801can perform spatial filtering in order to increase the gain of the signal carried on the identified beam.

As noted above, the process of receiving a set of second-node beams (as at814), determining a time of arrival for each (as at820), and identifying a positioning subset (as at830), is performed with respect to the set of second-node beams811-813received from the second node802. As shown elsewhere inFIG. 8, the process may be repeated with respect to the third node803and a set of third-node beams841-843transmitted therefrom.

At840, the third node803transmits the set of third-node beams including a first beam841, a second beam842, and a third beam843. The transmitting may be analogous to the transmitting performed by the second node802at810.

At844, the first node801receives the set of third-node beams. The receiving may be analogous to the receiving performed by the first node801at814.

At850, the first node801determines one or more times of arrival for each beam in the set of third-node beams. The determining may be analogous to the determining performed by the first node801at820.

At860, the first node801identifies a positioning subset of third-node beams based on the one or more times of arrival determined at850. The identifying may be analogous to the identifying performed by the first node801at830.

At870, the first node801determines a timing metric based on the one or more times of arrival of the beams in the identified positioning subsets. For example, as will be discussed in greater detail below, the first node801may calculate an OTDOA timing metric.

In the present example, suppose that the second node802sends out a second-node timing beacon using a set of eight different second-node beams, and the third node803sends out a third-node timing beacon using a set of fourteen different third-node beams. The first node801may receive the set of eight different second-node beams (at814) and the set of fourteen different third-node beams (at844). At820, the first node801may determine that beam #3 has the earliest time of arrival of all the beams in the set of eight different second-node beams. For example, beam #3 may arrive from the second node802two-hundred samples after the start of a signal reception window (for example, a Discrete Fourier transform (DFT) window), with all other beams in the set of second-node beam arriving after more than two-hundred samples. At850, the first node801may determine that beam #10 has the earliest time of arrival of all the beams in the set of fourteen different third-node beams. For example, beam #10 may arrive from the second node802two-hundred and fifty samples after the start of the signal reception window, with all other beams in the set of third-node beam arriving after more than two-hundred and fifty samples.

Accordingly, the first node801may identify beam #3 of the set of second-node beams as being the second-node positioning subset (at830). The first node801may further identify beam #10 of the set of third-node beams as being the third-node positioning subset (at860). At870, the first node801may use the times of arrival of beam #3 of the set of second-node beams and beam #10 of the set of third-node beams to calculate a timing metric. In particular, the first node801may calculate a difference between the times of arrival (250−200=50 samples). This value may constitute an OTDOA timing metric that can be used, in conjunction with other calculations, to determine a position of the first node801. It will be further understood that while beam #3 and beam #10 are used for positioning applications, a different beam altogether may be used for data communication. The use may be simultaneous. For example, beam #7 of the set of second-node beams may have the highest signal strength of any of the beams received at814or844. Accordingly, the first node801may use beam #7 of the set of second-node beams to perform data communication.

To perform OTDOA positioning, the first node801may calculate two time difference values. The first node801selects a reference node (for example, the second node802) and two neighbor nodes (for example, the third node803and a fourth node (substantially similar to the third node803, but omitted fromFIG. 8for brevity)). The first time difference value OTDOA1may be determined by calculating a difference between the times of arrival for signals received from the second node802and the third node803(for example, 50 samples, as in the previous example). This process is shown inFIG. 8. The second time difference value OTDOA2may be determined by calculating a difference between the times of arrival for signals received from the second node802and the fourth node. Once the two time difference values OTDOA1and OTDOA2have been calculated, they can be used to determine a set of distances between the first node801and the other three nodes (the second node802, the third node803, and the fourth node). If the positions of the other three nodes are known (for example, by latitude, longitude, and/or altitude), then the position of the first node801can be determined using known multilateration techniques.

The aforementioned positioning calculations may be performed at the first node801using the components of the first node801. In this case, the absolute positions of the other three nodes may be, for example, stored at and/or communicated to the first node801. Alternatively, measurement results (for example, times of arrival and/or OTDOAs) may be transmitted to an external device (for example, a location server) and the external device may use or calculate the time difference values OTDOA1and OTDOA2to determine a position of the first node801. In this case, the absolute positions of the other three nodes need only be stored in the location server. To report the two time difference values OTDOA1and OTDOA2to the location server, it may be necessary to identify the nodes and/or beams that were used to calculate the two time difference values OTDOA1and OTDOA2. The result of the position determination may be used at the location server to perform other calculations, transmitted to another server, or transmitted back to the first node801.

FIG. 9illustrates another exemplary signal flow diagram, according to various aspects.FIG. 9depicts a first node901, a second node902, and a third node903analogous to the first node801, the second node802, and the third node803depicted inFIG. 8. InFIG. 9, the timing metric is calculated differently from the timing metric calculated inFIG. 8. In particular, the set of beams are transmitted from the first node901, rather than to the first node901(as depicted inFIG. 8).

At910, the first node901transmits a set of first-node beams, including a first beam911, a second beam912, and a third beam913. For illustrative purposes, three beams are depicted inFIG. 9, but it will be understood that any number of beams may be transmitted at910. Further, the set of beams may include one or more spatially-multiplexed beams analogous to the beamforming184depicted inFIG. 1or the beams511-515depicted inFIG. 5. The set of beams may be simultaneously transmitted at910.

At914, the second node902receives the set of beams. As discussed previously, each beam in the set of first-node beams may travel a different path from the second node902to the first node901. For example, the first beam911and the third beam913may travel NLOS paths, whereas the second beam912may travel an LOS path.

At920, the second node902determines one or more times of arrival for each beam in the set of first-node beams. For example, the first beam911may have a first range of times of arrival, the second beam912may have a second range of times of arrival, and the third beam913may have a third range of times of arrival. The times of arrival for each beam may be determined at920in any suitable manner, as noted above in the description ofFIG. 8.

At930, the second node902identifies a positioning subset of beams based on the one or more times of arrival determined at920. The positioning subset of beams may include one or more beams from the set of first-node beams received at914, but may omit one or more other beams from the set of first-node beams received at914. For example, the second beam912may have earlier times of arrival than the first beam911and the third beam913. Accordingly, the second beam912may be included in the position subset of first-node beams identified at930, whereas the first beam911and the third beam913may be omitted.

As noted above, the process of receiving a set of first-node beams (as at914), determining a time of arrival for each (as at920), and identifying a positioning subset (as at930) is performed at the second node902with respect to the set of first-node beams911-913received from the first node901. As shown inFIG. 9, the process may be repeated with respect to the third node903.

At944, the third node903receives the set of first-node beams.FIG. 9clearly illustrates the set of beams911-913being received at the second node902. The set of beams911-913may also be received at the third node903, although signal flow arrows are partially omitted for clarity of illustration. Generally, it will be understood that the third node903receives a set of first-node beams from the first node901, which may be identical to or analogous to the beams911-913received by the second node902.

At950, the third node903determines one or more times of arrival for each beam in the set of first-node beams. The determining may be analogous to the determining performed by the first node901at920.

At960, the third node903identifies a positioning subset of first-node beams based on the one or more times of arrival determined at920. The identifying may be analogous to the identifying performed by the first node901at920.

At970, the second node902and the third node903may coordinate to determine a timing metric based on the relative times of arrival of the beams in the identified positioning subsets. For example, the second node902may transmit to (or receive from) the third node903data relating to times of arrival associated with the positioning subset of beams identified at930(or960). Additionally, or alternatively, the second node902and the third node903may both transmit data relating to times of arrival to, for example, the first node901, a location server (not shown), and/or another suitable node. In this case, the first node901, location server, or another suitable node may use the two times of arrival to determine a timing metric analogous to the OTDOA1(described above with respect toFIG. 8).

The methods, sequences, and/or algorithms described in connection with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in Random Access Memory (RAM), flash memory, Read-Only Memory (ROM), Erasable Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), registers, hard disk, a removable disk, a CD-ROM, or any other form of non-transitory computer-readable medium known in the art. An exemplary non-transitory computer-readable medium may be coupled to the processor such that the processor can read information from, and write information to, the non-transitory computer-readable medium. In the alternative, the non-transitory computer-readable medium may be integral to the processor. The processor and the non-transitory computer-readable medium may reside in an ASIC. The ASIC may reside in a user device (e.g., a UE) or a base station. In the alternative, the processor and the non-transitory computer-readable medium may be discrete components in a user device or base station.

While the foregoing disclosure shows illustrative aspects, those skilled in the art will appreciate that various changes and modifications could be made herein without departing from the scope of the disclosure as defined by the appended claims. Furthermore, in accordance with the various illustrative aspects described herein, those skilled in the art will appreciate that the functions, steps, and/or actions in any methods described above and/or recited in any method claims appended hereto need not be performed in any particular order. Further still, to the extent that any elements are described above or recited in the appended claims in a singular form, those skilled in the art will appreciate that singular form(s) contemplate the plural as well unless limitation to the singular form(s) is explicitly stated.