Antenna coherence indication for arrival phase difference and deviation angle estimation

Abstract

A technique is disclosed to determine an angle of departure (AoD) of a signal transmitted from a set of transmission points associated with a transmitter (e.g., a base station, a user equipment (UE)). In one aspect, the set of transmission points are co-located and transmit coherent signals. A receiver (e.g., a UE, a network entity) determines a phase difference of arrival (PDoA) of the signal. Based on the PDoA and the positioning of the set of transmission points, the AoD may be calculated. When the UE is a receiver, the network entity may transmit a base station almanac (BSA) message to the UE indicating the set of transmission points and their positioning.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims priority under 35 U.S.C. §119 to Greek Patent Application No. 20180100373, filed on August 8, 2018, entitled “INDICATION OF ANTENNA COHERENCE FOR PHASE DIFFERENCE OF ARRIVAL AND ANGLE OF DEPARTUREESTIMATION,” and U.S. Non-Provisional Patent Application No. 16 / 534,830, filed on August 7, 2019, entitled “INDICATION OF ANTENNA COHERENCE FOR PHASE DIFFERENCE OF ARRIVAL AND ANGLE OF DEPARTUREESTIMATION,” both of which are assigned to the assignee of the present invention and are expressly incorporated herein by reference in their entirety. Technical Field

[0003] Various aspects described herein relate generally to wireless communication systems, and more particularly, to indication of antenna coherence of phase difference of arrival (PDoA) and angle of deviation (AoD) estimates. Background Art

[0004] Wireless communication systems have evolved over several generations, including first generation analog wireless telephone service (1G), second generation (2G) digital wireless telephone service (including temporary 2.5G and 2.75G networks), third generation (3G) high speed data, Internet-enabled wireless services, and fourth generation (4G) services (e.g., Long Term Evolution (LTE) or WiMax). There are many different types of wireless communication systems in use today, including cellular and personal communications service (PCS) systems. Examples of known cellular systems include the cellular analog Advanced Mobile Phone System (AMPS), and digital cellular systems based on code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), global system for mobile access (GSM) variants of TDMA, and the like.

[0005] The fifth generation (5G) mobile standard calls for higher data transfer speeds, more connections, and better coverage, among other improvements. According to the Next Generation Mobile Networks Alliance, the 5G standard is designed to provide data rates of tens of megabits per second for each of tens of thousands of users and 1 gigabit per second for dozens of employees on an office floor. To support large sensor deployments, hundreds of thousands of simultaneous connections should be supported. Therefore, the spectrum efficiency of 5G mobile communications should be significantly enhanced compared to the current 4G standard. In addition, signaling efficiency should be enhanced and latency should be significantly reduced compared to the current standard.

[0006] Some wireless communication networks (such as 5G) support operation at very high frequencies and even extremely high frequencies (EHF) bands, such as millimeter wave (mmW) bands (typically, wavelengths of 1 mm to 10 mm, or 30 to 300 GHz). These extremely high frequencies can support very high throughputs, such as up to 6 gigabits per second (Gbps). However, one of the challenges of wireless communication at very high frequencies or extremely high frequencies is that significant propagation losses may occur due to the high frequencies. As the frequency increases, the wavelength may decrease, and the propagation losses may also increase. In the mmW band, the propagation losses may be severe. For example, relative to what is observed in the 2.4 GHz or 5 GHz bands, the propagation losses may be about 22 to 27 dB.

[0007] Propagation loss is also a problem in multiple-input multiple-output (MIMO) and large-scale MIMO systems in any frequency band. As used herein, the term MIMO generally refers to both MIMO and large-scale MIMO. MIMO is a method of increasing the capacity of a radio link by utilizing multipath propagation using multiple transmit and receive antennas. Multipath propagation occurs because radio frequency (RF) signals propagate not only through the shortest path between the transmitter and the receiver (which may be a line of sight (LOS) path), but also through many other paths, because they spread out from the transmitter and are reflected by other objects on the way to the receiver, such as mountains, buildings, water, etc. The transmitter in the MIMO system includes multiple antennas and utilizes multipath propagation by directing these antennas to each send the same RF signal to the receiver on the same radio channel. The receiver is also equipped with multiple antennas tuned to the radio channel, which can detect the RF signal sent by the transmitter. When the RF signal arrives at the receiver (some RF signals may be delayed due to 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 transmitting a single RF signal, propagation loss is also a problem in the MIMO system.

[0008] To address the propagation loss problem in mmW band systems and MIMO systems, the transmitter can use beamforming to extend the RF signal coverage. In particular, transmit beamforming is a technique for transmitting RF signals in a specific direction, while receive beamforming is a technique for increasing the receive sensitivity of RF signals that arrive at a receiver along a specific direction. Transmit beamforming and receive beamforming can be used in conjunction with or separately from each other, and references to "beamforming" hereinafter may refer to transmit beamforming, receive beamforming, or both. Traditionally, when a transmitter broadcasts an RF signal, it broadcasts the RF signal in almost all directions determined by a fixed antenna directional pattern or an antenna radiation directional pattern. Through beamforming, the transmitter determines that a given receiver is positioned relative to the transmitter and projects a stronger downlink RF signal in that specific direction, thereby providing the receiver with a faster (in terms of data rate) and stronger RF signal. In order to change the directivity of the RF signal when transmitting, the 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 called a "phased array" or "antenna array") that creates an RF beam that can be "steered" to point in different directions without actually moving the antennas. Specifically, RF current is fed to the individual antennas in the correct phase relationship so that the radio waves from the individual antennas add together to increase radiation in the desired direction, while canceling the radio waves from the individual antennas to suppress radiation in undesired directions.

[0009] To support position estimation in terrestrial wireless networks, a mobile device may be configured to measure and report an 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).

[0010] In the case where a transmitter uses beamforming to transmit an RF signal, the beam of interest for data communication between the transmitter and the receiver will be the beam carrying the RF signal with the highest received signal strength (or the highest received signal-to-noise-plus-interference ratio (SINR), e.g., in the presence of a directional interfering signal). However, when a receiver relies on the beam with the highest received signal strength, the receiver's ability to perform certain tasks may be affected. For example, in a scenario where the beam with the highest received signal strength propagates on a longer NLOS path than the shortest path (i.e., a LOS path or a shortest non-LOS (NLOS) path), the RF signal may arrive later than an RF signal received on the shortest path due to propagation delays. Therefore, if the receiver is performing a task that requires precise timing measurements and the beam with the highest received signal strength is affected by the longer propagation delay, the beam with the highest received signal strength may not be optimal for the task at hand. Summary of the invention

[0011] The following content presents a brief summary of the invention related to one or more aspects disclosed herein. As such, the following summary of the invention should not be considered as a broad overview related to all expected aspects, nor should it be considered as identifying key or important elements related to all expected aspects or describing the scope associated with any particular aspect. Therefore, the sole purpose of the following summary of the invention is to present certain concepts related to one or more aspects of the mechanism disclosed herein in a simplified form before the detailed description presented below.

[0012] One aspect relates to a first node, comprising a memory, a receiver, and a processor coupled to the memory and the receiver. The processor may be configured to receive, via the receiver, an almanac message from a network entity indicating a set of transmission points associated with a second node. The set of transmission points may be collocated and configured to transmit coherent signals. The processor may also be configured to receive, via the receiver, coherent signals transmitted from at least two transmission points of the set of transmission points of the second node. The processor may also be configured to determine one or more phase differences of arrival (PDoAs) between the received coherent signals. Between any two transmission points in the set of transmission points, the signals transmitted from the two transmission points may be distinguishable from each other in a time domain, a frequency domain, a code domain, or any combination thereof.

[0013] One aspect relates to a network entity, comprising a memory, a communication interface, and a processor coupled to the memory and the communication interface. The processor may be configured to provide an almanac message indicating a set of transmission points associated with a second node to a first node via the communication interface. The set of transmission points may be co-located and configured to transmit coherent signals. Between any two transmission points in the set of transmission points, the signals transmitted from the two transmission points may be distinguishable from each other in a time domain, a frequency domain, a code domain, or any combination thereof.

[0014] One aspect relates to a method of operating a first node. The method may include receiving an almanac message indicating a set of transmission points associated with a second node from a network entity. The set of transmission points may be co-located and configured to transmit a coherent signal. The method may also include receiving the coherent signal transmitted from at least two transmission points of the set of transmission points of the second node. The method may also include determining one or more phase differences of arrival (PDoAs) between the received coherent signals. Between any two transmission points in the set of transmission points, the signals transmitted from the two transmission points may be distinguishable from each other in the time domain, the frequency domain, the code domain, or any combination thereof.

[0015] One aspect relates to a method of operating a network entity. The method may include providing an almanac message to a first node indicating a set of transmission points associated with a second node. The set of transmission points may be co-located and configured to transmit coherent signals. Between any two transmission points in the set of transmission points, signals transmitted from the two transmission points may be distinguishable from each other in the time domain, the frequency domain, the code domain, or any combination thereof.

[0016] One aspect relates to a first node. The first node may include means for receiving an almanac message indicating a set of transmission points associated with a second node from a network entity. The set of transmission points may be co-located and configured to transmit coherent signals. The first node may also include means for receiving coherent signals transmitted from at least two transmission points of the set of transmission points of the second node. The first node may also include means for determining one or more phase differences of arrival (PDoA) between the received coherent signals. Between any two transmission points in the set of transmission points, the signals transmitted from the two transmission points may be distinguishable from each other in the time domain, the frequency domain, the code domain, or any combination thereof.

[0017] One aspect relates to a network entity. The network entity may include means for providing an almanac message to a first node indicating a set of transmission points associated with a second node. The set of transmission points may be co-located and configured to transmit coherent signals. Between any two transmission points in the set of transmission points, the signals transmitted from the two transmission points may be distinguishable from each other in the time domain, the frequency domain, the code domain, or any combination thereof.

[0018] One aspect relates to a non-transitory computer-readable medium containing instructions stored thereon executable by a first node. The instructions cause the first node to receive an almanac message from a network entity indicating a set of transmission points associated with a second node. The set of transmission points may be co-located and configured to transmit coherent signals. The instructions may also cause the first node to receive coherent signals transmitted from at least two transmission points of the set of transmission points of the second node. The instructions may also cause the first node to determine one or more phase differences of arrival (PDoAs) between the received coherent signals. Between any two transmission points in the set of transmission points, the signals transmitted from the two transmission points may be distinguishable from each other in the time domain, the frequency domain, the code domain, or any combination thereof.

[0019] One aspect relates to a non-transitory computer-readable medium containing instructions stored thereon executable by a network entity. The instructions may cause the network entity to provide an almanac message to a first node indicating a set of transmission points associated with a second node. The set of transmission points may be co-located and configured to transmit coherent signals. Between any two transmission points in the set of transmission points, the signals transmitted from the two transmission points may be distinguishable from each other in the time domain, the frequency domain, the code domain, or any combination thereof.

[0020] Other objects and advantages associated with the aspects disclosed herein will be apparent to those skilled in the art based on the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] A more complete understanding of the various aspects described herein and many of their attendant advantages will be readily obtained when the same becomes better understood by reference to the following detailed description considered in conjunction with the accompanying drawings, which are intended for illustration only and not limitation, and wherein:

[0022] Figure 1 An exemplary wireless communication system according to various aspects is shown;

[0023] Figure 2A and Figure 2B illustrates an exemplary wireless network structure according to various aspects;

[0024] Figure 3A An exemplary base station and an exemplary UE in an access network according to various aspects are shown;

[0025] Figure 3B An exemplary server according to various aspects is shown;

[0026] Figure 4 An exemplary wireless communication system according to various aspects is shown;

[0027] Figure 5 An exemplary wireless communication system according to various aspects is shown;

[0028] Fig. 6A is a graph illustrating RF channel response at a UE over time according to various aspects;

[0029] Figure 6B shows an exemplary separation of clusters in angle of departure (AoD) according to various aspects;

[0030] Fig. 7A illustrates an exemplary arrangement of co-located transmission ports for estimating AoD according to various aspects;

[0031] Figure 7B illustrates a graphical relationship between observed phase difference of arrival (OPDoA) measurements from which AoD may be derived in accordance with various aspects; and

[0032] Figure 8-Figure 12 Exemplary methods according to various aspects are shown. DETAILED DESCRIPTION

[0033] Various aspects described herein relate generally to wireless communication systems, and more particularly to phase difference of arrival (PDoA) and angle of deviation (AoD) estimation. In an aspect, a network entity (e.g., a positioning server, a base station) may provide an almanac message (e.g., a base station almanac (BSA)) to a first node (e.g., a UE). The almanac message may indicate a set of transmission points associated with a second node (e.g., a base station), and the first node may perform measurements on signals sent from the set of transmission points. In particular, the first node may determine a PDoA of the signal. The first node may also determine or estimate an AoD of the signal based on the PDoA, and / or may provide the PDoA to the network entity.

[0034] These and other aspects are disclosed in the following description and related drawings to show specific examples related to the exemplary aspects. Upon reading this disclosure, alternative aspects will be apparent to those skilled in the relevant art and may be constructed and practiced without departing from the scope or spirit of the disclosure. In addition, well-known elements will not be described in detail or may be omitted so as not to obscure the relevant details of the aspects disclosed herein.

[0035] The word "exemplary" is used herein to mean serving as an example, instance, or illustration. Any aspect described herein as "exemplary" is not necessarily to be construed as being superior or advantageous over other aspects. Likewise, the term "aspect" does not require that all aspects include the discussed features, advantages, or modes of operation.

[0036] The terms used herein describe only specific aspects and should not be construed as limiting any aspect disclosed herein. As used herein, the singular forms "a", "an" and "said" are intended to also include plural forms unless the context clearly indicates otherwise. It will be further understood by those skilled in the art that the terms "comprising" and / or "including" as used herein specify the presence of the described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0037] In addition, various aspects may be described in terms of a sequence of actions to be performed by, for example, an element of a computing device. Those skilled in the art will recognize that the various actions described herein may be performed by a specific circuit (e.g., an application specific integrated circuit (ASIC)), by program instructions executed by one or more processors, or by a combination of the two. In addition, these action sequences described herein may be considered to be all embodied in any form of non-transitory computer-readable medium, on which a corresponding set of computer instructions is stored, which, when executed, will cause the associated processor to perform the functions described herein. Therefore, the various aspects described herein may be embodied in many different forms, all of which are considered to be within the scope of the claimed subject matter. In addition, for each aspect described herein, the corresponding form of any such aspect may be described herein as, for example, "logic configured as..." and / or other structural components configured to perform the described actions.

[0038] As used herein, the terms "user equipment" (or "UE"), "user device", "user terminal", "client device", "communication device", "wireless device", "wireless communication device", "handheld device", "mobile device", "mobile terminal", "mobile station", "handset", "access terminal", "subscriber device", "subscriber terminal", "subscriber station", "terminal" and variations thereof may interchangeably refer to any suitable mobile or fixed device capable of receiving wireless communications and / or navigation signals. These terms are also intended to include devices that communicate with another device that may receive wireless communications and / or navigation signals, such as via short-range wireless, infrared, wired connections, or other connections, regardless of whether satellite signal reception, assistance data reception, and / or location-related processing occurs at the device or at another device. In addition, these terms are intended to include all devices, including wireless and wired communication devices, that may communicate with a core network via a radio access network (RAN), and the UE may connect to external networks such as the Internet and other UEs through the core network. Of course, other mechanisms for the UE to connect to the core network and / or the Internet are also possible, such as through a wired access network, a wireless local area network (WLAN) (e.g., based on IEEE 802.11, etc.), etc. The UE may be embodied by any of a variety of types of devices, including but not limited to a printed circuit (PC) card, a compact flash device, an external or internal modem, a wireless or wired phone, a smart phone, a tablet computer, a tracking device, an asset tag, etc. The communication link through which the UE may transmit signals to the RAN is referred to as an uplink channel (e.g., a reverse traffic channel, a reverse control channel, an access channel, etc.). The communication link through which the RAN may transmit signals to the UE is referred to as 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) may refer to an uplink / reverse or downlink / forward traffic channel.

[0039] According to various aspects, Figure 1 An exemplary wireless communication system 100 is shown. The wireless communication system 100 (which may also be referred to as a wireless wide area network (WWAN)) may include various base stations 102 and various UEs 104. The base stations 102 may 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), wherein the wireless communication system 100 corresponds to an LTE network or a gNodeB (gNB), wherein the wireless communication system 100 corresponds to a 5G network or a combination of both, and the small cells may include femto cells, pico cells, micro cells, etc.

[0040] The base stations 102 may collectively form a radio access network (RAN) and interface with an evolved packet core (EPC) or a next generation core (NGC) via a backhaul link. In addition to other functions, the base stations 102 may perform functions related to one or more of the following: delivery of user data, radio channel encryption and decryption, integrity protection, header compression, mobility control functions (e.g., switching, dual connectivity), inter-cell interference coordination, connection establishment and release, load balancing, distribution of non-access stratum (NAS) messages, NAS node selection, synchronization, RAN sharing, multimedia broadcast multicast service (MBMS), subscriber and equipment tracking, RAN information management (RIM), paging, location determination (positioning) and delivery of warning messages. The base stations 102 may communicate with each other directly or indirectly (e.g., via EPC / NGC) via a backhaul link 134 (which may be wired or wireless).

[0041] Base stations 102 can communicate wirelessly with UEs 104. Each of base stations 102 can provide communication coverage for a corresponding geographic coverage area 110. In one aspect, although Figure 1 1, but the geographic coverage area 110 may be subdivided into multiple cells (e.g., three) or sectors, each cell corresponding to a single antenna or antenna array of the base station 102. As used herein, the term "cell" or "sector" may correspond to one of the multiple cells of the base station 102, or to the base station 102 itself, depending on the context.

[0042] Although adjacent macrocell geographic coverage areas 110 may partially overlap (e.g., in a handover region), some geographic coverage areas 110 may be substantially overlapped by a larger geographic coverage area 110. For example, a small cell base station 102' may have a geographic coverage area 110' that substantially overlaps with the geographic coverage area 110 of one or more macrocell base stations 102. A network including both small cells and macrocells may be referred to as a heterogeneous network. A heterogeneous network may also include a home eNB (HeNB), which may provide services to a restricted group referred to as a closed subscriber group (CSG). A communication link 120 between a base station 102 and a UE 104 may include an uplink (UL) (also referred to as a reverse link) transmitted from the UE 104 to the base station 102 and / or a downlink (DL) (also referred to as a forward link) transmitted from the base station 102 to the UE 104. The communication link 120 may use MIMO antenna technology, including spatial multiplexing, beamforming, and / or transmit diversity. The communication link may be through one or more carriers. The allocation of carriers may be asymmetric with respect to DL and UL (eg, more or fewer carriers may be allocated to DL than to UL).

[0043] The wireless communication system 100 may also include a wireless local area network (WLAN) access point (AP) 150 that communicates with a WLAN station (STA) 152 in an unlicensed spectrum (e.g., 5 GHz) via a communication link 154. When communicating in the unlicensed spectrum, the WLAN STA 152 and / or the WLAN AP 150 may perform a clear channel assessment (CCA) to determine whether a channel is available before communicating.

[0044] The small cell base station 102' can operate in licensed and / or unlicensed spectrum. When operating in the unlicensed spectrum, the small cell base station 102' can adopt LTE or 5G technology and use the same 5GHz unlicensed spectrum used by the WLAN AP 150. The small cell base station 102' adopting LTE / 5G in the unlicensed spectrum can improve the coverage of the access network and / or increase the capacity of the access network. LTE in the unlicensed spectrum can be called LTE-Unlicensed (LTE-U), Licensed Assisted Access (LAA) or MulteFire.

[0045] The wireless communication system 100 may also include a mmW base station 180, which can operate in mmW frequencies and / or near mmW frequencies to communicate with UE 182. Extremely high frequency (EHF) is part of RF in the electromagnetic spectrum. EHF has a range of 30GHz to 300GHz and a wavelength between 1 mm and 10 mm. Radio waves in this band can be called millimeter waves. Near mmW can be extended down to a frequency of 3GHz and a wavelength of 100 mm. The super high frequency (SHF) band extends between 3GHz and 30GHz, also known as centimeter waves. Communications using mmW / near mmW radio frequency bands have high path losses and relatively short distances. The mmW base station 180 can utilize beamforming 184 with UE 182 to compensate for extremely high path losses and short distances. In addition, it will be appreciated that in alternative configurations, one or more base stations 102 can also use mmW or near mmW and beamforming to send. Therefore, it will be appreciated that the foregoing description is merely an example and should not be interpreted as limiting the various aspects disclosed herein.

[0046] The wireless communication system 100 may also include one or more UEs (such as UE 190) that are indirectly connected to one or more communication networks via one or more device-to-device (D2D) peer-to-peer (P2P) links. Figure 1In an embodiment of the present invention, UE 190 has a D2D P2P link 192 with one of UEs 104 connected to one of base stations 102 (e.g., UE 190 can indirectly obtain cellular connectivity through the link), and a D2D P2P link 194 with a WLAN STA 152 connected to WLAN AP 150 (UE 190 can indirectly obtain WLAN-based Internet connectivity through the link). In an example, the D2D P2P links 192-194 can be supported by any well-known D2D radio access technology (RAT), such as LTE Direct (LTE-D), WiFi Direct (WiFi-D), Bluetooth, etc.

[0047] According to various aspects, Figure 2A An exemplary wireless network architecture 200 is shown. For example, the next generation core (NGC) 210 can be functionally viewed as a control plane function 214 (e.g., UE registration, authentication, network access, gateway selection, etc.) and a user plane function 212 (e.g., UE gateway function, access to data networks, IP routing, etc.), which operate in conjunction to form a core network. A user plane interface (NG-U) 213 and a control plane interface (NG-C) 215 connect the gNB 222 to the NGC 210, and specifically to the control plane function 214 and the user plane function 212. In an additional configuration, the eNB 224 can also be connected to the NGC 210 via the NG-C 215 to the control plane function 214 and to the user plane function 212 via the NG-U 213. In addition, the eNB 224 can communicate directly with the gNB 222 via the backhaul connection 223. Thus, in some configurations, the new RAN 220 may have only one or more gNBs 222, while other configurations include one or more of the eNBs 224 and the gNBs 222. The gNB 222 or the eNB 224 may communicate with the UE 240 (e.g., Figure 1 240). Another optional aspect may include a positioning server 230 that can communicate with the NGC 210 to provide positioning assistance to the UE 240. The positioning server 230 may be implemented as a plurality of structurally separate servers, or alternatively may each correspond to a single server. The positioning server 230 may be configured to support one or more positioning services for the UE 240, which may be connected to the positioning server 230 via the core network, the NGC 210, and / or via the Internet (not shown). In addition, the positioning server 230 may be integrated into a component of the core network, or alternatively may be external to the core network.

[0048] According to various aspects, Figure 2BAnother exemplary wireless network structure 250 is shown. For example, the NGC 260 can be functionally considered as a control plane function, an access and mobility management function (AMF) 264 and a user plane function, and a session management function (SMF) 262, which operate in conjunction to form a core network. The user plane interface 263 and the control plane interface 265 connect the eNB 224 to the NGC 260, and specifically to the AMF 264 and the SMF 262. In an additional configuration, the gNB 222 can also be connected to the NGC 260 via the control plane interface 265 to the AMF 264 and via the user plane interface 263 to the SMF 262. In addition, the eNB 224 can communicate directly with the gNB 222 via the backhaul connection 223, regardless of whether the gNB is directly connected to the NGC 260. Therefore, in some configurations, the new RAN 220 may have only one or more gNBs 222, while other configurations include one or more of the eNB 224 and the gNB 222. The gNB 222 or the eNB 224 may communicate with the UE 204 (e.g., Figure 1 240). Another optional aspect may include a location management function (LMF) 270 that can communicate with the NGC 260 to provide positioning assistance for the UE 240. The LMF 270 may be implemented as multiple separate servers (e.g., physically separate servers, different software modules on a single server, different software modules spread across multiple physical servers, etc.), or alternatively may each correspond to a single server. The LMF 270 may be configured to support one or more positioning services for the UE 204, which may be connected to the LMF 270 via the core network, the NGC 260, and / or via the Internet (not shown).

[0049] According to various aspects, Figure 3AAn exemplary base station 310 (e.g., eNB, gNB, small cell AP, WLAN AP, etc.) is shown communicating with an exemplary UE 350 in a wireless network. In the DL, IP packets from the core network (NGC 210 / EPC 260) may be provided to a controller / processor 375. The controller / processor 375 implements the functionality of the radio resource control (RRC) layer, the packet data convergence protocol (PDCP) layer, the radio link control (RLC) layer, and the medium access control (MAC) layer. The controller / processor 375 provides: RRC layer functionality associated with broadcasting of system information (e.g., MIB, SIB), 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 delivery of upper layer packet data units (PDUs), error correction through ARQ, concatenation of RLC service data units (SDUs), segmentation and reassembly, 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.

[0050] The transmit (TX) processor 316 and the receive (RX) processor 370 implement layer 1 functionality associated with various signal processing functions. Layer 1, including the physical (PHY) layer, may include error detection on the transmission channel, forward error correction (FEC) encoding / decoding of the transmission channel, interleaving, rate matching, mapping to the physical channel, modulation / demodulation of the physical channel, and MIMO antenna processing. The TX processor 316 handles the mapping to the signal constellation based on various modulation schemes (e.g., binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), M-phase shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded and modulated symbols can then be separated into parallel streams. Each stream can then be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time domain and / or frequency domain, and then combined using an inverse fast Fourier transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially precoded to produce multiple spatial streams. Channel estimates from a channel estimator 374 may be used to determine coding and modulation schemes, as well as for spatial processing. The channel estimate may be derived from a reference signal and / or channel condition feedback transmitted by the UE 350. Each spatial stream may then be provided to one or more different antennas 320 via a separate transmitter 318a. Each transmitter 318a may modulate an RF carrier with a corresponding spatial stream for transmission.

[0051] At the UE 350, each receiver 354a receives a signal through its corresponding antenna 352. Each receiver 354a recovers the information modulated onto the RF carrier and provides the information to the RX processor 356. The TX processor 368 and the RX processor 356 implement layer 1 functionality associated with various signal processing functions. The RX processor 356 can perform spatial processing on the information to recover any spatial stream destined for the UE 350. If multiple spatial streams are destined for the UE 350, they can be combined into a single OFDM symbol stream by the RX processor 356. The RX processor 356 then converts the OFDM symbol stream from the time domain to the frequency domain using a fast Fourier transform (FFT). The frequency domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. By determining the most likely signal constellation point sent by the base station 310, the symbol and reference signal on each subcarrier are recovered and demodulated. These soft decisions can be based on the channel estimate calculated by the channel estimator 358. The soft decisions are then decoded and deinterleaved to recover the data and control signals originally sent on the physical channel by the base station 310. The data and control signals are then provided to the controller / processor 359 which implements layer 3 and layer 2 functionality.

[0052] The controller / processor 359 may be associated with a memory 360 that stores program codes and data. The memory 360 may be referred to as a computer readable medium. In the UL, the controller / processor 375 provides demultiplexing between transport and logical channels, packet reassembly, decryption, header decompression, and control signal processing to recover IP packets from the core network. The controller / processor 359 is also responsible for error detection.

[0053] Similar to the functionality described in conjunction with DL transmission of base station 310, the controller / processor 359 provides: RRC layer functionality associated with system information (e.g., MIB, SIB) acquisition, RRC connection, and measurement reporting; PDCP layer functionality associated with header compression / decompression and security (encryption, decryption, integrity protection, integrity verification); RLC layer functionality associated with delivery of upper layer PDUs, error correction through ARQ, concatenation, segmentation and reassembly of RLC SDUs, resegmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing MAC SDUs to TBs, demultiplexing MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

[0054] Channel estimates derived by the channel estimator 358 from a reference signal or feedback transmitted by the base station 310 may be used by the TX processor 368 to select the appropriate coding and modulation schemes and to facilitate spatial processing. The spatial streams generated by the TX processor 368 may be provided to different antennas 352 via separate transmitters 354 b. Each transmitter 354 b may modulate an RF carrier with a corresponding spatial stream for transmission.

[0055] The UL transmission is processed at the base station 310 in a manner similar to that described in conjunction with the receiver functionality at the UE 350. Each receiver 318b receives a signal through its respective antenna 320. Each receiver 318b recovers information modulated onto an RF carrier and provides the information to the RX processor 370.

[0056] The controller / processor 375 may be associated with a memory 376 that stores program codes and data. The memory 376 may be referred to as a computer readable medium. In the UL, the controller / processor 375 provides demultiplexing between transport and logical channels, packet reassembly, decryption, header decompression, control signal processing to recover IP packets from the UE 350. The IP packets from the controller / processor 375 may be provided to the core network. The controller / processor 375 is also responsible for error detection.

[0057] Figure 3BAn exemplary server 300B is shown. In an example, the server 300B may correspond to the exemplary configuration of the positioning server 230 described above. The server 300B includes a processor 301B coupled to a volatile memory 302B and a large capacity non-volatile memory (such as a disk drive 303B). The server 300B may also include a floppy disk drive, a compact disk (CD), or a DVD optical disk drive 306B coupled to the processor 301B. The server 300B may also include a network access port 304B coupled to the processor 301B for establishing a data connection with a network 307B, such as a local area network coupled to other broadcast system computers and servers or coupled to the Internet.

[0058] Figure 4 An exemplary wireless communication system 400 is shown in accordance with aspects of the present disclosure. Figure 4 In the example of , UE 404 may correspond to the above Figure 1 Any of the UEs described (e.g., UE 104, UE 182, UE 190, etc.) is attempting to compute an estimate of its location, or assist another entity (e.g., a base station or core network component, another UE, a positioning server, a third-party application, etc.) in computing an estimate of its location. UE 404 can wirelessly communicate with multiple base stations 402a-d (collectively, base stations 402) using RF signals and standardized protocols for RF signal modulation and information packet exchange, which can correspond to Figure 1 By extracting different types of information from the exchanged RF signals and utilizing the layout of the wireless communication system 400 (i.e., base station locations, geometry, etc.), the UE 102 can determine its position in a predefined reference coordinate system, or assist in determining its position. In one aspect, the UE 404 can use a two-dimensional coordinate system to specify its position; however, the aspects disclosed herein are not limited thereto and may also be adapted to use a three-dimensional coordinate system to determine position if additional dimensions are required. Additionally, although Figure 4 One UE 404 and four base stations 402 are shown, but it will be appreciated that there may be more UEs 404 and more or fewer base stations 402.

[0059] To support position estimation, the base station 402 may be configured to broadcast reference RF signals (e.g., position determination reference signals (PRS), cell-specific reference signals (CRS), channel state information reference signals (CSI-RS), synchronization signals, etc.) to the UE 404 in its coverage area to enable the UE 404 to measure reference RF signal timing differences (e.g., OTDOA or RSTD) between pairs of network nodes, and / or to identify beams that best excite LOS or shortest radio paths between the UE 404 and the transmitting base station 402. Identifying LOS / shortest path beams is of interest not only because these beams can then be used for OTDOA measurements between a pair of base stations 402, but also because identifying these beams can directly provide some position determination information based on the beam direction. In addition, these beams can then be used for other position estimation methods that require accurate ToA, such as methods based on round-trip time estimation.

[0060] As used herein, a "network node" may be a base station 402, a cell of a base station 402, a remote radio head, an antenna of a base station 402, wherein the positioning of the antenna of the base station 402 is different from the positioning of the base station 402 itself, or any other network entity capable of sending a reference signal. In addition, as used herein, a "node" may refer to a network node or a UE.

[0061] A positioning server (e.g., positioning server 230) may send assistance data to UE 404, the assistance data including identification of one or more neighboring cells of base station 402 and configuration information of reference RF signals transmitted by each neighboring cell. Alternatively, the assistance data may originate directly from base station 402 itself (e.g., in a periodically broadcast overhead message, etc.). Alternatively, UE 404 may detect neighboring cells of base station 402 itself without using assistance data. UE 404 (e.g., based in part on assistance data, if provided) may measure and (optionally) report OTDOA from various network nodes and / or RSTD between reference RF signals received from pairs of network nodes. Using these measurements and the known location of the measured network node (i.e., base station 402 or antenna that transmits the reference RF signal measured by UE 404), UE 404 or the positioning server may determine the distance between UE 404 and the measured network node, and thereby calculate the location of UE 404.

[0062] The term "position estimate" is used herein to refer to an estimate of the location of UE 404, which may be geographic (e.g., may include latitude, longitude, and possibly altitude) or urban (e.g., may include a street address, a building name, or a precise point or area within or near a building or street address, such as a specific entrance to a building, a specific 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," "position," "fix," "position fix," "position fix," "position estimate," "fix estimate," or some other term. The manner in which a position estimate is obtained may be collectively referred to as "positioning," "locating," or "position fix." A specific solution for obtaining a position estimate may be referred to as a "position solution." A specific method for obtaining a position estimate as part of a position solution may be referred to as a "position method" or "position determination method."

[0063] The term "base station" may refer to a single physical transmission point, or to multiple physical transmission points, which 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 a base station (e.g., base station 402) corresponding to a cell of the base station. Where the term "base station" refers to multiple co-located physical transmission points, the physical transmission point may be an antenna array of the base station (e.g., as in a MIMO system or where the base station employs beamforming). Where the term "base station" refers to multiple non-co-located physical transmission points, the physical transmission point may be a distributed antenna system (DAS) (a network of spatially separated antennas connected to a common source via a transmission 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 a serving base station that receives measurement reports from a UE (e.g., UE 404) and a neighboring base station whose reference RF signal the UE is measuring. Thus, Figure 4 Base stations 402a and 402b are shown to form an aspect of DAS / RRH 420. For example, base station 402a can be a serving base station for UE 404, and base station 402b can be a neighboring base station for UE 404. As such, base station 402b can be an RRH for base station 402a. Base stations 402a and 402b can communicate with each other via a wired or wireless link 422.

[0064] In order to accurately determine the location of UE 404 using OTDOA and / or RSTD between RF signals received from a pair of network nodes, UE 404 needs to measure a reference RF signal received on a LOS path (or the shortest NLOS path if the LOS path is not available) between UE 404 and a network node (e.g., base station 402, antenna). However, RF signals propagate not only through the LOS / shortest path between a transmitter and a receiver, but also through many other paths as the RF signals spread out from the transmitter and are reflected by other objects on the way to the receiver, such as mountains, buildings, water, etc. Therefore, Figure 4 A number of LOS paths 410 and a number of NLOS paths 412 are shown between base station 402 and UE 404. Specifically, Figure 4 Base station 402a is shown transmitting via LOS path 410a and NLOS path 412a, base station 402b is shown transmitting via LOS path 410b and two NLOS paths 412b, base station 402c is shown transmitting via LOS path 410c and NLOS path 412c, and base station 402d is shown transmitting via two NLOS paths 412d. Figure 4 As shown, each NLOS path 412 is reflected by an object 430 (e.g., a building). As will be appreciated, each LOS path 410 and NLOS path 412 transmitted by base station 402 may be transmitted by a different antenna of base station 402 (e.g., as in a MIMO system), or may be transmitted by the same antenna of base station 402 (thereby illustrating the propagation of RF signals). Furthermore, as used herein, the term "LOS path" refers to the shortest path between a transmitter and a receiver, and may not be the actual LOS path, but rather the shortest NLOS path.

[0065] Each LOS path 410 and NLOS path 412 represents a path followed by an RF signal. An "RF signal" includes electromagnetic waves that transmit information through space between a transmitter and a receiver. Figure 4 As shown and described further below, due to the propagation characteristics of RF signals through multipath channels, a receiver (e.g., UE 404) may receive multiple "RF signals" corresponding to each transmitted RF signal. More specifically, when a transmitter (e.g., base station 402) transmits an RF signal, the RF signal received at the receiver (e.g., UE 404) is the sum or accumulation of RF signals received through multiple paths. For example, UE 404 may combine RF signals received through LOS path 410c and NLOS path 412c into a single RF signal. Since the signal paths may have different lengths and arrive at the receiver from different directions, such as Figure 4As shown, the RF signal from each path is delayed and arrives at a specific angle. This directivity effect is more significant at higher frequencies, such as mmW.

[0066] In receive beamforming, the receiver uses receive beams to amplify RF signals detected on a given channel. For example, the receiver may increase the gain setting and / or adjust the phase setting of an antenna array (e.g., antenna 352 in FIG. 3 ) in a particular direction to amplify (e.g., increase its gain level) the RF signals received from that direction. Thus, when a receiver is said to be beamforming in a certain direction, this means that the beam gain in that direction is high relative to the beam gain along other directions, or that the beam gain in that direction is the highest compared to the beam gain in that direction of all other receive beams available to the receiver. This results in a stronger received signal strength (e.g., RSRP, SINR, etc.) of the RF signals received from that direction.

[0067] Figure 5 An exemplary wireless communication system 500 is shown in accordance with aspects of the present disclosure. Figure 5 In the example of , UE 504 may correspond to Figure 4 UE 404 in the network is attempting to calculate an estimate of its location, or assist another entity (e.g., a base station or core network component, another UE, a positioning server, a third-party application, etc.) to calculate an estimate of its location. UE 504 can wirelessly communicate with base station 502 using RF signals and standardized protocols for RF signal modulation and information packet exchange, which can correspond to Figure 4 One of the base stations 402 in.

[0068] like Figure 5 As shown, base station 502 is using beamforming to transmit multiple beams 511-515 of RF signals. Each beam 511-515 can be formed and transmitted by an antenna array of base station 502. Figure 5 Base station 502 is shown transmitting five beams, but it will be appreciated that there may be more or less than five beams, that beam shapes such as peak gain, width, and sidelobe gain may differ between transmitted beams, and that some beams may be transmitted by different base stations.

[0069] In order to distinguish an RF signal associated with one beam from an RF signal associated with another beam, a beam index may be assigned to each of the plurality of beams 511-515. In addition, an RF signal associated with a particular beam in the plurality of beams 511-515 may carry a beam index indicator. The beam index may also be derived from the transmission time of the RF signal (e.g., frame, time slot, and / or number of OFDM symbols). The beam index indicator may be, for example, a three-bit field that uniquely distinguishes up to eight beams. If two different RF signals with different beam indices are received, this would indicate that the RF signals are transmitted using different beams. If two different RF signals share a common beam index, this 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 (multiple) antenna ports used to transmit the first RF signal are spatially quasi-co-located with the antenna ports used to transmit the second RF signal.

[0070] exist Figure 5 In the example of FIG. 5 , UE 504 receives NLOS stream 523 of RF signals transmitted on beam 513 and LOS stream 524 of RF signals transmitted on beam 514. Figure 5 NLOS stream 523 and LOS stream 524 are shown as single lines (dashed and solid, respectively), as will be appreciated, due to, for example, the propagation characteristics of RF signals through multipath channels, NLOS stream 523 and LOS stream 524 may each include multiple rays (i.e., "clusters") when arriving at UE 504. For example, when electromagnetic waves reflect from multiple surfaces of an object, clusters of RF signals are formed, and the reflections arrive at a receiver (e.g., UE 504) from approximately the same angle, with each reflection propagating a few wavelengths (e.g., centimeters) more or less than the other reflections. A "cluster" of received RF signals generally corresponds to a single transmitted RF signal.

[0071] exist Figure 5 In the example of FIG. 5 , although NLOS flow 523 is not initially directed to UE 504, as will be appreciated, it may be Figure 4 4. However, it is reflected by reflector 540 (e.g., a building) and reaches UE 504 without obstruction, and thus can still be a relatively strong RF signal. In contrast, LOS stream 524 is directed toward UE 504, but passes through obstacle 530 (e.g., plants, buildings, mountains, disruptive environments such as clouds or smoke, etc.), which may significantly degrade the RF signal. As will be appreciated, although LOS stream 524 is weaker than NLOS stream 523, LOS stream 524 will reach UE 504 before NLOS stream 523 because it follows a shorter path from base station 502 to UE 504.

[0072] As described above, the beam of interest for data communication between a base station (e.g., base station 502) and a UE (e.g., UE 504) is a beam carrying an RF signal that arrives at the UE with the highest signal strength (e.g., highest RSRP or SINR), while the beam of interest for position estimation is a beam carrying an RF signal that excites the LOS path and has the highest gain along the LOS path among all other beams (e.g., beam 514). That is, even though beam 513 (NLOS beam) excites the LOS path weakly (even if not focused along the LOS path due to the propagation characteristics of the RF signal), the weak signal (if any) of the LOS path of beam 513 may not be reliably detected (compared to the signal from beam 514), resulting in a larger error when performing position determination measurements.

[0073] Although the beam of interest for data communication and the beam of interest for position estimation may be the same beam for some frequency bands, they may not be the same beam for other frequency bands, such as mmW. Figure 5 , when UE 504 is conducting a data communication session with base station 502 (e.g., where base station 502 is the serving base station for UE 504), rather than simply attempting to measure a reference RF signal transmitted by base station 502, the beam of interest for the data communication session may be beam 513 because it carries an unobstructed NLOS stream 523. However, the beam of interest for position estimation would be beam 514 because it carries the strongest LOS stream 524, despite being obstructed.

[0074] Fig. 6A 600A shows the RF channel response at a receiver (eg, UE 504) over time in accordance with aspects of the present disclosure. Fig. 6A In the illustrated channel, the receiver receives a first cluster of two RF signals on a channel tap at time T1, a second cluster of five RF signals on the channel tap at time T2, a third cluster of five RF signals on the channel tap at time T3, and a fourth cluster of four RF signals on the channel tap at time T4. Fig. 6A In the example of , because the first cluster of RF signals at time T1 arrives first, it is presumed to be a LOS flow (i.e., a flow that arrives via LOS or the shortest path), and may correspond to LOS flow 524. The third cluster at time T3 includes the strongest RF signal, and may correspond to NLOS flow 523. From the transmitter side, each cluster of received RF signals may include portions of RF signals transmitted at different angles, and therefore each cluster may be said to have a different angle of deviation (AoD) from the transmitter. Figure 6B600B shows this separation of clusters in the AoD. The RF signal transmitted in the AoD range 602a may correspond to Fig. 6A , and the RF signal transmitted in AoD range 602b may correspond to Fig. 6A . Note that although Figure 6B The AoD ranges of the two clusters depicted in are spatially isolated, but the AoD ranges of some clusters can also partially overlap, even if the clusters are separated in time. This can occur, for example, when two separate buildings reflect signals from the transmitter to the receiver at the same AoD. It should be noted that although Fig. 6A Clusters of two to five channel taps are shown, as will be appreciated, the clusters may have more or fewer channel taps than shown.

[0075] As in Figure 5 In the example of , a base station may utilize beamforming to transmit multiple RF signal beams such that one of the beams (e.g., beam 514) is directed toward the AoD range 602a of a first cluster of RF signals, and a different beam (e.g., beam 513) is directed toward the AoD range 602b of a third cluster of RF signals. The signal strength of a cluster in the post-beamforming channel response (i.e., the channel response when the transmitted RF signals are beamformed rather than omnidirectional) will be scaled by the beam gain along the AoD of the cluster. In this case, the beams of interest for position determination will be the beams directed toward the AoD of the first cluster of RF signals because they arrive first, and the beams of interest for data communications may be the beams directed toward the AoD of the third cluster of RF signals because they are the strongest.

[0076] Typically, when transmitting an RF signal, the transmitter does not know what path it will follow to reach the receiver (e.g., UE 504) or at what time it will arrive at the receiver, and therefore transmits the RF signal on different antenna ports with equal energy. Alternatively, the transmitter may beamform the RF signal in different directions at multiple transmission occasions and obtain measurement feedback from the receiver to determine the radio path explicitly or implicitly.

[0077] It should be noted that while the techniques disclosed herein are generally 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. Furthermore, while beamforming is generally described above in conjunction with transmit beamforming, in certain embodiments, receive beamforming may also be used in conjunction with the transmit beamforming described above.

[0078] As described above, in some frequency bands, the shortest path (which may be a LOS path or the shortest NLOS path, as described above) may be weaker than an alternative longer (NLOS) path (through which the RF signal arrives later due to propagation delays). Therefore, where a transmitter uses beamforming to transmit RF signals, the beam of interest for data communication (the beam carrying the strongest RF signal) may be different from the beam of interest for position estimation (the beam carrying the RF signal that excites the shortest detectable path). As such, it would be beneficial for a receiver to identify and report to the transmitter the beam of interest for position estimation so that the transmitter can then modify the set of transmit beams to assist the receiver in performing position estimation.

[0079] So far, OTDOA-based position estimation techniques have been discussed. But when the transmitter antennas are co-located, i.e., the distance between the antennas is comparable to the carrier wavelength (e.g., in the range of 10 wavelengths or less), OTDOA-based triangulation / multilateration may become impractical, for example, because the arrival time difference from the co-located transmission points may be too small to be accurately measured by the receiver. However, through the observed phase difference of arrival (OPDoA) measurement, the co-located antenna ports can still be used for AoD estimation, and therefore position determination. But in order to perform AoD estimation, the transmitter antennas should be coherent, which is not always the case, especially at mmW carrier frequencies. Therefore, the receiver (e.g., UE) should be informed which antenna ports of the transmitter can be considered coherent.

[0080] Fig. 7A An exemplary arrangement for estimating AoD based on OPDoA measurements when a transmitter (TX) sends multiple signals to a receiver (RX) is shown. The TX may be equipped with multiple antennas (e.g., four antennas) to transmit signals. Antennas may also be referred to as "transmission ports" (TPs). Fig. 7A In the example, it is assumed that the TX (e.g., base station) is equipped with four transmission points and sends signals to the RX at an angle θ (i.e., AoD) with the transmission points. The assumptions are as follows:

[0081] The transmission points are co-located (the transmission points are separated by at most a few wavelengths λ);

[0082] The transmitted signals are coherent (same frequency, fixed phase relationship); and

[0083] • The transmitted signals are all distinguishable from each other (in the time domain, frequency domain and / or code domain).

[0084] exist Fig. 7A, assuming four transmission points are located at positions a1, a2, a3, and a4. Since the transmission points are co-located, this means that the spacing between the positions (e.g., between a1 and a2) is at most a few wavelengths λ of the carrier. In practice, the spacing may even be less than a single λ. Due to the physical spacing of the transmission points, the distances traveled by signals sent to the RX from different transmission points will be different, which will appear as phase changes relative to each other at the RX. In other words, the received phase relationship will be different from the transmitted phase relationship. Then, by observing the PDoA of the signal at the receiver RX, the AoDθ can be estimated.

[0085] The process can generally be described as follows: First, let d ij ≡a i -a j (in units of wavelength λ), and ω≡2πsinθ. Then assume that the coherent transmission point, from the transmission point a i -a j The PDoA between the signals Δ ij It can be expressed as The RX can measure the phase difference Δ between the signals received from transmission points (e.g., antenna ports) i and j ij .

[0086] Figure 7B shows a graphical relationship between the OPDoA from which the AoD can be derived. There can be multiple AoD solutions To derive a unique AoD solution, three or more transmission points may be specified from which PDoA measurements can be made. In addition, for all (i,j)≠(k,l) or at least for some (i,j)≠(k,l)), the transmission points may be placed non-uniformly for redundancy, e.g., d ij ≠d kl The former is similar to the Costas array, which can be described as a distribution of points in a grid, where each row or column of the grid contains only one point, and all displacement vectors between each pair of points are different. Since the transmission points are distributed in this way, redundancy can be provided so that a unique AoD solution can be obtained through PDoA measurement.

[0087] Figure 8-Figure 12 Exemplary methods according to various aspects of the present disclosure are shown. Figure 8-Figure 12 All of the illustrated boxes need to be executed, i.e., some boxes may be optional. Figure 8-Figure 12 The reference numbers of the blocks should not be construed as requiring that the blocks should be performed in a particular order. In fact, some blocks may be performed simultaneously.

[0088] Figure 8An exemplary method 800 for determining AoD according to an aspect of the present disclosure is shown. The method 800 involves a first and a second node (referred to as a "receiver" and a "transmitter" respectively). In one aspect, the first and second nodes are a UE and a base station of a network, respectively. In another aspect, the first and second nodes are a base station and a UE, respectively. That is, both the UE and the base station can play the role of a transmitter and a receiver. At 805, the second node transmits a signal from a set of transmission points. If the second node is a base station, the set of transmission points is associated with the base station. If the second node is a UE, the set of transmission points is associated with the UE.

[0089] In one aspect, a set of transmission points are co-located and configured to transmit coherent signals. The signals transmitted by the transmission points may be reference RF signals (e.g., pilots, PRS, CRS, CSI-RS), synchronization signals (e.g., SS, PBCH blocks), random access preambles, etc. In addition, the signals transmitted from the set of transmission points are distinguishable from each other in one or more of the time domain, the frequency domain, and the code domain.

[0090] At 810, a first node receives a coherent signal transmitted from at least two transmission points of a set of transmission points of a second node. At 820, the first node measures or otherwise determines a PDoA of the received coherent signal. In one aspect, at 830, the first node reports the PDoA to a network entity (e.g., a base station, a positioning server, etc.). For example, the first node can be a UE that reports the PDoA back to the second node (e.g., a base station). In this aspect, at 835, the second node receives the PDoA from the UE. Then, at 845, the second node or some other network entity (e.g., a positioning server) estimates or otherwise determines an AoD of the transmitted signal based on the reported PDoA.

[0091] It should be noted that in order to determine the AoD, the positioning of the set of transmitting nodes should also be known. It is assumed that the network entity has this knowledge. When receiving the PDoA from the UE, the network entity can calculate the AoD based on the received PDoA and the positioning of the set of transmitting locations.

[0092] Alternatively or additionally, at 840, the first node estimates or otherwise determines the AoD based on the determined PDoA. For example, when the UE is the first node, the UE determines the AoD of the signal transmitted from the transmission point of the second node. In another example, when the base station is the first node, the network entity (e.g., base station, positioning server) determines the AoD of the signal transmitted from the transmission point of the UE. At 850, the first node may report the AoD, and at 855, the second node may receive the AoD report.

[0093] The above discussion shows that the UE can measure the PDoA between signals. However, in general, the UE does not know which transmission point signals to measure to determine the PDoA. In one aspect of the present disclosure, it is proposed that a network entity such as a positioning server or a base station provides the UE with a list or set of transmission points that transmit coherent signals. With this knowledge, the UE can measure the signals sent from the set of transmission points and determine their PDoA. Figure 8 As can be seen in FIG. 1 , the UE can estimate the AoD of the signal based on the measured PDoA. Alternatively or additionally, the UE can report the measured PDoA back to the network, and the network entity can estimate the AoD.

[0094] Fig. 9 An exemplary method 900 for providing base station almanac (BSA) information to a UE is shown. The method 900 involves a UE and a network entity (e.g., a base station, a positioning server, etc.) having knowledge about a set of transmission points. At 910, the UE requests a BSA message from the network entity. At 915, the network entity receives the BSA message request. At 925, the network entity sends the BSA message. The network entity may then proceed to Figure 8 At 805, the UE receives the BSA message at 930. The UE may then proceed to Figure 8 of 810. Fig. 9 It is shown that, at 910, the UE may initiate by requesting BSA information. Alternatively, at 925, the network entity may initiate by providing BSA information to the UE.

[0095] In one aspect, the BSA message indicates a set of transmission points associated with the base station. The BSA message may be one message or multiple messages. The set of transmission points is co-located. That is, the spacing between the transmission points is comparable to the wavelength λ of the carrier signal sent from the set of transmission points. For example, the transmission points may be separated by no more than ten wavelengths. Some transmission points may be separated by even less than a single wavelength λ.

[0096] The transmission point set transmits signals that are all distinguishable from each other. That is, the signals are orthogonal (or nearly orthogonal) to each other in any one or more of the time domain, the frequency domain, and the code domain. In other words, between any two transmission points in the transmission point set, the signals transmitted from the two transmission points are distinguishable from each other in the time domain, the frequency domain, the code domain, or any combination thereof.

[0097] The signals transmitted by the set of transmission points are also coherent, i.e., the signals are all transmitted at the same frequency and with a known or determined phase relationship. An example of a known or determined phase relationship is a fixed phase relationship, and an example of a fixed phase relationship is a zero phase relationship, i.e., the phases of all signals are aligned when transmitted. In another example, the phase relationship between adjacent transmission points may be offset by a fixed amount, e.g., 30 degrees.

[0098] The BSA message from the network entity indicates the set of transmission points of the base station that transmits the coherent signal. With this knowledge, the UE can measure the transmitted signals and determine the PDoA between the signals received from the set of transmission points, since the signals are all distinguishable from each other (see, for example, Figure 8 810 and 820).

[0099] The BSA message may also indicate a phase relationship between the transmitted signals. For example, a fixed phase relationship between the transmitted signals may be indicated. If the phase relationship is indicated in the BSA message, the UE may compensate when determining the true PDoA. For example, if the UE measures the PDoA between the first and second signals (sent from the first and second transmission points, respectively) as 45 degrees, but the BSA message indicates that the first and second signals are sent with a 30 degree offset, the UE may determine that the actual PDoA is 15 degrees. If the phase relationship is not indicated in the BSA message, the UE may assume a fixed phase relationship of zero.

[0100] The UE itself can determine the AoD of the signal based on the PDoA. To enable AoD determination, the BSA message also indicates the location of the set of transmission points. Based on the measured PDoA and the location of the indicated set of transmission points, the UE can determine the AoD (e.g., see Figure 8 840). The UE may report the AoD back to the network entity (e.g., see Figure 8 850 and 855).

[0101] If the BSA message does not indicate the location of the transmission point set and / or the network entity requests PDoA measurement, the UE may report back the PDoA to the network entity (e.g., see Figure 8 830). Presumably, the network entity knows the locations of the set of transmission points. With this knowledge and based on the reported PDoA, the network entity can determine the AoD (e.g., see Figure 8 835 and 845).

[0102] When the location of the set of transmission points is known more accurately, the accuracy of the calculated AoD increases. In one embodiment, the BSA message indicates the location of the set of transmission points with an accuracy better than the wavelength of the coherent signal. Optionally, the location uncertainty of the transmission point may be included in the BSA message. This may allow the UE or any location determination entity to determine whether the location of the transmission point is known with the desired accuracy. In another embodiment, in addition to the location of the set of transmission points, the BSA message may include information about the accuracy of the location. For example, the BSA message may include a flag indicating "accuracy better than the wavelength of the coherent signal".

[0103] Preferably, the BSA message indicates the positioning of the set of transmission points in at least two dimensions. If the positioning is indicated in two dimensions, the azimuth of the AoD can be calculated. If the positioning is indicated in three dimensions, the azimuth and altitude of the AoD can be calculated.

[0104] Recall from above that between any two transmission points, when the interval between them exceeds half a wavelength, that is, when When To solve this problem and derive a unique AoD solution, the transmission point set may include three or more transmission points. In addition, the distribution of the transmission point set is preferably non-uniform. That is, the positioning of the transmission point set makes the spacing between the transmission point sets non-uniform. This can provide redundancy so that there is a better possibility of calculating a unique AoD.

[0105] The network entity may select a set of transmission points from a super set of transmission points. In this way, even if the transmission points within the super set are uniformly distributed, a set may be selected such that the transmission points within the selected set are non-uniformly distributed.

[0106] A set of transmission points may be selected so that the coherent signals sent from the set of transmission points are all signals of the same beam. This may be useful when the approximate location of the UE is known. If the approximate location is within the path of the beam, the transmission points of the set may be selected accordingly. In this way, a more accurate AoD determination may be made.

[0107] On the other hand, if the UE is not in the path of the beam, the UE may not be able to detect one or more signals of the beam. Therefore, if it is not known whether the UE is in the path of any beam, a transmission point that transmits a broader (less focused) signal may be selected for the set of transmission points. In other words, at least one coherent signal transmitted from the set of transmission points does not form a beam with at least one other coherent signal.

[0108] exist Fig. 9 In the example, the UE is the receiver or first node, and the network entity (e.g., base station, positioning server) is the transmitter. However, these roles can be reversed, such as Fig.10 As can be seen, an exemplary method 1000 for causing a UE to transmit a coherent signal is shown. At 1005, the network entity transmits a command to the UE to transmit a coherent signal. The network entity may then proceed to Figure 8 At 810, the UE receives a command from a network entity. The UE may then proceed to Figure 8 805. The AoD of the signal can be determined.

[0109] Fig.11A method 1100 is shown, typically performed by a first node. At block 1110, the first node may receive an almanac message from a network entity (e.g., a base station, a positioning server, etc.). In one aspect, if the first node is a UE, the means for performing block 1110 may include the controller / processor 339 and / or the RX processor 356 of the UE 350 shown in FIG. 3. If the first node is a base station, the means for performing block 810 may include the controller / processor 375 and / or the RX processor 370 of the base station 310 shown in FIG. 3. The almanac message may indicate a set of transmission points associated with a second node (e.g., a base station, a UE). The set of transmission points may be co-located and configured to transmit coherent signals. A BSA may be an example of an almanac message.

[0110] At block 1120, the first node may receive coherent signals transmitted from at least two transmission points of the set of transmission points of the second node. In one aspect, if the first node is a UE, the means for performing block 1120 may include the controller / processor 339 and / or the RX processor 356 of the UE 350 shown in FIG3. If the first node is a base station, the means for performing block 1120 may include the controller / processor 375 and / or the RX processor 370 of the base station 310 shown in FIG3.

[0111] At block 1130, the first node may determine one or more phase differences of arrival (PDoA) between the received coherent signals. In one aspect, if the first node is a UE, the means for performing block 1120 may include the controller / processor 339 of the UE 350 shown in FIG. 3. If the first node is a base station, the means for performing block 1120 may include the controller / processor 375 of the base station 310 shown in FIG. 3. Between any two transmission points in the set of transmission points, the signals sent from the two transmission points may be distinguishable from each other in the time domain, the frequency domain, the code domain, or any combination thereof.

[0112] Fig.12 A method 1200 is shown that is typically performed by a network entity (e.g., a positioning server, a base station). In block 1210, the network node may provide an almanac message to a first node (e.g., a UE, a base station). In one aspect, if the network entity is a positioning server, the means for performing block 1210 may include a processor 301B and / or a network access port 304B, which may also be referred to as a communication interface. If the network entity is a base station, the means for performing block 1210 may include a controller / processor 375 and / or a TX processor 316 of the base station 310 shown in FIG. 3. It should be noted that any combination of the TX processor 316, the RX processor 370, the transmitter 318a, and the receiver 318b may be referred to as a communication interface.

[0113] The almanac message may indicate a set of transmission points associated with the second node (e.g., a base station, a UE). The set of transmission points may be co-located and configured to transmit coherent signals. A BSA may be an example of an almanac message. In addition, between any two transmission points in the set of transmission points, the signals transmitted from the two transmission points may be distinguishable from each other in the time domain, the frequency domain, the code domain, or any combination thereof.

[0114] Those skilled in the art will recognize that information and signals may be represented using any of a variety of different techniques and technologies. For example, data, instructions, commands, information, signals, bits, symbols, and chips referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0115] In addition, those skilled in the art will recognize that the various illustrative logic blocks, modules, circuits, and algorithm steps described in conjunction with the aspects disclosed herein can be implemented as electronic hardware, computer software, or a combination of the two. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally with respect to their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the entire system. Those skilled in the art may implement the described functionality in different ways for each specific application, but such implementation decisions should not be interpreted as departing from the scope of the various aspects described herein.

[0116] The various illustrative logical blocks, modules, and circuits described in conjunction with the aspects disclosed herein may be implemented or executed using a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in an alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or other such configurations).

[0117] The methods, sequences and / or algorithms described in conjunction with the aspects disclosed herein may be directly embodied in hardware, software modules executed by a processor, or a combination of the two. The software module may reside in a random access memory (RAM), a flash memory, a read-only memory (ROM), an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a register, a 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 a processor so that the processor can read information from the non-transitory computer-readable medium and write information to the non-transitory computer-readable medium. In an alternative, the non-transitory computer-readable medium may be integrated with the processor. The processor and the non-transitory computer-readable medium may reside in an ASIC. The ASIC may reside in a user equipment (e.g., UE) or a base station. In an alternative, the processor and the non-transitory computer-readable medium may be discrete components in a user equipment or a base station.

[0118] In one or more exemplary aspects, the functions described herein can be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the function can be stored on or sent by a non-transitory computer-readable medium as one or more instructions or codes. Computer-readable media may include storage media and / or communication media, including any non-transitory media that can help transfer a computer program from one place to another. Storage media can be any available medium that can be accessed by a computer. For example (and not limited to), such computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage bodies, disk storage bodies, or other magnetic storage devices, or any other medium that can be used to carry or store the desired program code in the form of an instruction or data structure and can be accessed by a computer. Moreover, any connection is appropriately referred to as a computer-readable medium. For example, if software is sent from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwaves, then coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwaves are included in the definition of medium. The terms disk and disc, which may be used interchangeably herein, include compact disc (CD), laser disc, optical disc, digital video disc (DVD), floppy disk and Blu-ray disc, which typically reproduce data magnetically and / or optically using lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0119] Although the foregoing disclosure presents illustrative aspects, those skilled in the art will recognize that various changes and modifications may be made herein without departing from the scope of the present disclosure as defined by the appended claims. In addition, based on the various illustrative aspects described herein, those skilled in the art will understand that the functions, steps, and / or actions in any method described above and / or referenced in any method claim attached hereto need not be performed in any particular order. In addition, with respect to any element described above or referenced in the appended claims in the singular, those skilled in the art will understand that the singular also encompasses the plural unless a limitation to the singular is explicitly stated.

Claims

1. A first node, comprising: Memory; Receiver; as well as a processor, coupled to the memory and the transceiver, Wherein, the processor is configured to: receiving, by the receiver, from a network entity an almanac message indicating a set of transmission points associated with a second node, the set of transmission points being co-located and configured to transmit a coherent signal, receiving, by the receiver, coherent signals transmitted from at least two transmission points of the transmission point set of the second node, and determining one or more phase differences of arrival PDoA between said coherent signals, Among them, between any two transmission points in the set of transmission points, signals sent from the two transmission points are distinguishable from each other in the time domain, the frequency domain, the code domain or any combination thereof, wherein the almanac message further indicates a phase relationship between the positioning of the set of transmission points and the transmitted coherent signal, the phase relationship being used to compensate for the determined PDoA, and The processor is further configured to determine an angle of deviation AoD of the received coherent signal based on the one or more PDoAs and the positioning of the transmission point set.

2. The first node according to claim 1, in, The positioning accuracy is better than the wavelength of the coherent signal.

3. The first node according to claim 1, wherein: The positioning of the set of transmission points indicated in the almanac message is in at least two dimensions.

4. The first node according to claim 1, wherein: The almanac message indicates that the positioning of the set of transmission points is such that the set of transmission points is non-uniformly distributed.

5. The first node according to claim 1, wherein: The coherent signals are all signals of the same beam.

6. The first node according to claim 1, wherein: At least one coherent signal is not beamformed with at least one other coherent signal.

7. The first node according to claim 1, further comprising a transmitter, in, The processor is further configured to report the one or more PDoAs to the network entity via the transmitter.

8. A network entity, comprising: Memory; Communication interface; as well as a processor coupled to the memory and the communication interface, wherein the processor is configured to provide, to the first node via the communication interface, an almanac message indicating a set of transmission points associated with the second node, the set of transmission points being co-located and configured to transmit a coherent signal, wherein, between any two transmission points in the set of transmission points, signals sent from the two transmission points are distinguishable from each other in the time domain, the frequency domain, the code domain, or any combination thereof, The almanac message further indicates a phase relationship between the positioning of the transmission point set and the transmitted coherent signal, wherein the phase relationship is used to compensate for the measured phase difference of arrival PDoA, The processor is further configured to receive, from the first node through the communication interface, angles of deviation AoD of two or more coherent signals among the coherent signals received at the first node, and The first node determines the AoD of the received coherent signal based on one or more PDoAs and the positioning of the transmission point set.

9. The network entity according to claim 8, in, The positioning accuracy is better than the wavelength of the coherent signal.

10. The network entity according to claim 8, wherein: The positioning of the set of transmission points indicated in the almanac message is in at least two dimensions.

11. The network entity according to claim 8, wherein: The almanac message indicates that the positioning of the set of transmission points is such that the set of transmission points is non-uniformly distributed.

12. The network entity according to claim 8, wherein: The coherent signals are all signals of the same beam.

13. The network entity according to claim 8, wherein: At least one coherent signal is not beamformed with at least one other coherent signal.

14. The network entity according to claim 8, wherein: The processor is further configured to: receiving from the first node via the communication interface one or more phase differences of arrival PDoA between coherent signals determined by the first node; and An angle of deviation AoD of a coherent signal from the set of transmission points is determined based on the one or more PDoAs and the locations of the set of transmission points.

15. A method of operating a first node, comprising: receiving an almanac message from a network entity indicating a set of transmission points associated with the second node, the set of transmission points being co-located and configured to transmit a coherent signal; receiving a coherent signal sent from at least two transmission points of the transmission point set of the second node; as well as determining one or more phase differences of arrival PDoA between said coherent signals, wherein, between any two transmission points in the set of transmission points, signals sent from the two transmission points are distinguishable from each other in the time domain, the frequency domain, the code domain, or any combination thereof, wherein the almanac message further indicates a phase relationship between the positioning of the set of transmission points and the transmitted coherent signal, the phase relationship being used to compensate for the determined PDoA, and The method further includes determining an angle of deviation AoD of the received coherent signal based on the one or more PDoAs and the positioning of the set of transmission points.

16. The method according to claim 15, in, The positioning accuracy is better than the wavelength of the coherent signal.

17. The method according to claim 15, wherein: The positioning of the set of transmission points indicated in the almanac message is in at least two dimensions.

18. The method according to claim 15, wherein: The almanac message indicates that the positioning of the set of transmission points is such that the set of transmission points is non-uniformly distributed.

19. The method according to claim 15, wherein: The coherent signals are all signals of the same beam.

20. The method of claim 15, further comprising: The one or more PDoAs are reported to the network entity.

21. A method of operating a network entity, comprising: providing an almanac message to the first node indicating a set of transmission points associated with the second node, the set of transmission points being co-located and configured to transmit a coherent signal, wherein, between any two transmission points in the set of transmission points, signals sent from the two transmission points are distinguishable from each other in the time domain, the frequency domain, the code domain, or any combination thereof, The almanac message further indicates a phase relationship between the positioning of the transmission point set and the transmitted coherent signal, wherein the phase relationship is used to compensate for the measured phase difference of arrival PDoA, The method further comprises receiving, from the first node, angles of deviation AoD of two or more coherent signals among the coherent signals received at the first node, and The first node determines the AoD of the received coherent signal based on one or more PDoAs and the positioning of the transmission point set.

22. The method according to claim 21, in, The positioning accuracy is better than the wavelength of the coherent signal.

23. The method according to claim 21, wherein: The positioning of the set of transmission points indicated in the almanac message is in at least two dimensions.

24. The method according to claim 21, wherein: The almanac message indicates that the positioning of the set of transmission points is such that the set of transmission points is non-uniformly distributed.

25. The method according to claim 21, wherein: The coherent signals are all signals of the same beam.

26. The method of claim 21, further comprising: receiving from the first node one or more phase differences of arrival PDoA between coherent signals determined by the first node; as well as An angle of deviation AoD of a coherent signal from the set of transmission points is determined based on the one or more PDoAs and the locations of the set of transmission points.

27. A non-transitory computer-readable storage medium storing instructions for wireless communications, the instructions causing a processor to: receiving an almanac message from a network entity indicating a set of transmission points associated with the second node, the set of transmission points being co-located and configured to transmit a coherent signal; receiving a coherent signal transmitted from at least two transmission points of the transmission point set of the second node; and determining one or more phase differences of arrival PDoA between said coherent signals, in, Between any two transmission points in the set of transmission points, signals sent from the two transmission points are distinguishable from each other in the time domain, the frequency domain, the code domain, or any combination thereof, wherein the almanac message further indicates a phase relationship between the positioning of the set of transmission points and the transmitted coherent signal, the phase relationship being used to compensate for the determined PDoA, and The instructions further cause the processor to determine an angle of deviation AoD of the received coherent signal based on the one or more PDoAs and the locations of the transmission point set.

28. A non-transitory computer-readable storage medium storing instructions for wireless communications, the instructions causing a processor to: providing an almanac message to the first node indicating a set of transmission points associated with the second node, the set of transmission points being co-located and configured to transmit a coherent signal, in, Between any two transmission points in the set of transmission points, signals sent from the two transmission points are distinguishable from each other in the time domain, the frequency domain, the code domain, or any combination thereof, The almanac message further indicates a phase relationship between the positioning of the transmission point set and the transmitted coherent signal, wherein the phase relationship is used to compensate for the measured phase difference of arrival PDoA, wherein the instructions further cause the processor to receive, from the first node, angles of deviation AoD of two or more coherent signals among the coherent signals received at the first node, and The first node determines the AoD of the received coherent signal based on one or more PDoAs and the positioning of the transmission point set.

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