Network nodes, user equipment, and methods for transmitting positioning reference signals

Abstract

Disclosed are techniques for transmitting reference signals for positioning estimation over a multipath multiple-input multiple-output (MIMO) channel and for processing the reference signals. In each aspect, a first node is configured to transmit a first reference signal resource set and a second reference signal resource set, wherein the first and second reference signal resource sets appear on a first subband and a second subband of the MIMO channel and / or during a first and a second time interval on the MIMO channel, wherein each reference signal resource in the first and second reference signal resource sets utilizes at least a first and a second MIMO precoder; and to transmit the first and second reference signal sets to a second node over the MIMO channel, wherein the first node transmits the first and second reference signal sets to assist the second node in performing positioning measurements based on joint processing of the first and second reference signal sets.

Description

[0001] This application is a divisional application of the application filed on July 17, 2019, with application number 201980046540.4 (international application number PCT / US2019 / 042256) entitled "Frequency / Time Selective Precoding for Positioning Reference Signals".

[0002] Cross-references to related applications

[0003] This patent application claims priority to Greek Patent Application No. 20180100328, filed July 17, 2018, entitled "FREQUENCY / TIME SELECTIVE PRECODING FOR POSITIONING REFERENCE SIGNALS IN NEW RADIO," and U.S. Nonprovisional Patent Application No. 16 / 513,433, filed July 16, 2019, entitled "FREQUENCY / TIME SELECTIVE PRECODING FOR POSITIONING REFERENCE SIGNALS IN NEW RADIO," both of which are assigned to the assignee of this application and are expressly incorporated herein by reference in their entirety. Technical Field

[0004] The various aspects described in this article generally relate to wireless communication systems, and in particular to frequency / time selective precoding for locating reference signals. Background Technology

[0005] Wireless communication systems have undergone several generations of development, including first-generation analog radiotelephone service (1G), second-generation (2G) digital radiotelephone service (including transitional 2.5G and 2.75G networks), third-generation (3G) high-speed data radio service with Internet capabilities, and fourth-generation (4G) service (e.g., Long Term Evolution (LTE) or WiMax). Currently, many different types of wireless communication systems are in use, including cellular and Personal Communication Services (PCS) systems. Known examples of cellular systems include cellular analog Advanced Mobile Phone Systems (AMPS), and digital cellular systems based on Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), and GSM TDMA variants.

[0006] The fifth-generation (5G) mobile standard demands higher data transmission speeds, a greater number of connections, better coverage, and other improvements. According to the Next Generation Mobile Networks Alliance (NGC), the 5G standard is designed to provide tens of megabits per second (Mbps) of data rate to each of tens of thousands of users, and 1 gigabits per second (Gbps) to dozens of employees on an office floor. It should support hundreds or thousands of simultaneous connections to support large-scale sensor deployments. Therefore, 5G mobile communication should have significantly improved spectral efficiency compared to the current 4G standard. Furthermore, signaling efficiency should be improved and latency significantly reduced compared to the current standard.

[0007] Some wireless communication networks, such as 5G, support operation at very high frequencies (VHF) 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 EHF bands can support very high throughputs, such as up to six gigabits per second (Gbps). However, one of the challenges of wireless communication at VHF or EHF is the significant propagation loss that can occur due to the high frequency. As the frequency increases, the wavelength may decrease, and propagation loss may also increase. At the mmW band, propagation loss can be severe. For example, propagation loss can be on the order of 22 to 27 dB compared to that observed in the 2.4 GHz or 5 GHz bands.

[0008] Propagation loss is a problem in both multiple-input multiple-output (MIMO) and massive MIMO systems across any frequency band. As used herein, the term MIMO generally refers to both MIMO and massive MIMO. MIMO is a method for multiplying the capacity of a radio link by utilizing multipath propagation through the use of multiple transmit and receive antennas. Multipath propagation occurs because radio frequency (RF) signals travel not only along the shortest path between the transmitter and receiver (which can be a line-of-sight (LOS) path), but also along several other paths as these RF signals spread from the transmitter and are reflected by other objects (such as hills, buildings, water, etc.) along their path to the receiver. In a MIMO system, the transmitter includes multiple antennas and utilizes multipath propagation by orienting these antennas to transmit 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 detect the RF signals transmitted by the transmitter. When the RF signals arrive at the receiver (some of which 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 it would otherwise send a single RF signal, propagation loss is also a problem in MIMO systems.

[0009] To support location estimation in terrestrial wireless networks, mobile devices can be configured to measure and report observed Time Difference of Arrival (“OTDOA”; OTDOA is also simply referred to as “Time Difference of Arrival” or “TDOA”) 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). For OTDOA-based positioning to be accurate, the receiver needs to be able to accurately estimate the LOS or earliest path of the channel. However, due to obstructions (e.g., hills, buildings, water, etc.), RF signals on LOS paths may be received with significantly lower power compared to RF signals on other non-LOS (NLOS) paths (multipaths). Therefore, the receiver may mistakenly treat any of these NLOS paths as a LOS path. Overview

[0010] The following is a simplified overview relating to one or more aspects disclosed herein. Thus, this overview should not be considered an exhaustive overview relating to all aspects of the conception, nor should it be considered to identify key or decisive elements relating to all aspects of the conception or to depict the scope associated with any particular aspect. Accordingly, the sole purpose of the following overview is to present, in a simplified form, certain concepts relating to one or more aspects of the mechanism disclosed herein before the detailed description given below.

[0011] In one aspect, a method for transmitting reference signals for positioning estimation over a multipath MIMO channel includes: configuring a first node to transmit a first reference signal resource set for a first set of reference signals, wherein the first reference signal resource set appears on a first subband of the MIMO channel and / or during a first time interval on the MIMO channel, and wherein each reference signal resource in the first reference signal resource set utilizes at least a first MIMO precoder; configuring the first node to transmit a second set of reference signal resources for a second set of reference signals, wherein the second reference signal resource set appears on a second subband of the MIMO channel and / or during a second time interval on the MIMO channel, and wherein the second reference signal resource set... Each reference signal resource in the source set utilizes at least a second MIMO precoder; the first node transmits a first reference signal set to the second node using a first reference signal resource set on the MIMO channel and / or during a first time interval on the MIMO channel; and the first node transmits the second reference signal set to the second node using a second reference signal resource set on the MIMO channel and / or during a second time interval on the MIMO channel, wherein the first node transmits the first and second reference signal sets to assist the second node in performing positioning measurements based on the joint processing of the first and second reference signal sets.

[0012] In one aspect, a method for processing reference signals for positioning estimation on a multipath MIMO channel includes: receiving, by a second node, a first set of reference signals on a first set of reference signal resources, wherein the first set of reference signal resources occurs on a first subband of the MIMO channel and / or during a first time interval on the MIMO channel, and wherein each reference signal resource in the first set of reference signal resources utilizes at least a first MIMO precoder; receiving, by the second node, a second set of reference signals on a second set of reference signal resources, wherein the second set of reference signal resources occurs on a second subband of the MIMO channel and / or during a second time interval on the MIMO channel, and wherein each reference signal resource in the second set of reference signal resources utilizes at least a second MIMO precoder; identifying, by the second node, at least one reference signal transmitted on the first and second sets of reference signal resources as following a LOS path between the second node and the first node; and performing a Time Difference of Arrival (TDOA) measurement by the second node based on the at least one reference signal.

[0013] In one aspect, an apparatus for transmitting reference signals for positioning estimation over a multipath MIMO channel includes: at least one processor of a first node, the at least one processor being configured to: configure a first reference signal resource set for transmitting a first set of reference signals, wherein the first set of reference signal resources occurs on a first subband of the MIMO channel and / or during a first time interval on the MIMO channel, and wherein each reference signal resource in the first set of reference signal resources utilizes at least a first MIMO precoder; and configure a second set of reference signal resources for transmitting a second set of reference signals, wherein the second set of reference signal resources occurs on a second subband of the MIMO channel and / or during a second time interval on the MIMO channel, and wherein the second set of reference signal resources utilizes at least a first MIMO precoder; and configure a second set of reference signal resources for transmitting a second set of reference signals, wherein the second set of reference signal resources occurs on a second subband of the MIMO channel and / or during a second time interval on the MIMO channel, and wherein the second set of reference signal resources utilizes at least a first MIMO precoder; Each reference signal resource in the reference signal resource set utilizes at least a second MIMO precoder; and a transmitter of a first node is configured to: transmit a first reference signal set to a second node using a first reference signal resource set on a first subband of the MIMO channel and / or during a first time interval on the MIMO channel; and transmit a second reference signal set to the second node using a second reference signal resource set on a second subband of the MIMO channel and / or during a second time interval on the MIMO channel, wherein the first node transmits the first and second reference signal sets to assist the second node in performing positioning measurements based on the joint processing of the first and second reference signal sets.

[0014] In one aspect, an apparatus for processing reference signals for positioning estimation on a multipath MIMO channel includes: a transceiver of a second node configured to: receive from a first node a first set of reference signals on a first set of reference signal resources, wherein the first set of reference signal resources appears on a first subband of the MIMO channel and / or during a first time interval on the MIMO channel, and wherein each reference signal resource in the first set of reference signal resources utilizes at least a first MIMO precoder; and receive from the first node a second set of reference signals on a second set of reference signal resources, wherein the second set of reference signal resources appears on a second subband of the MIMO channel and / or during a second time interval on the MIMO channel, and wherein each reference signal resource in the second set of reference signal resources utilizes at least a second MIMO precoder; and at least one processor of the second node configured to: identify at least one reference signal transmitted on the first and second sets of reference signal resources as following a LOS path between the second node and the first node; and perform a TDOA measurement by the second node based on the at least one reference signal.

[0015] In one aspect, an apparatus for transmitting reference signals for positioning estimation over a multipath MIMO channel includes: a processing means of a first node configured to: configure a first reference signal resource set for transmitting a first reference signal set, wherein the first reference signal resource set occurs on a first subband of the MIMO channel and / or during a first time interval on the MIMO channel, and wherein each reference signal resource in the first reference signal resource set utilizes at least a first MIMO precoder; and configure a second reference signal resource set for transmitting a second reference signal set, wherein the second reference signal resource set occurs on a second subband of the MIMO channel and / or during a second time interval on the MIMO channel, and wherein the second reference signal... Each reference signal resource in the resource set utilizes at least a second MIMO precoder; and a communication device for the first node is configured to: transmit a first reference signal set to the second node using a first reference signal resource set on the MIMO channel and / or during a first time interval on the MIMO channel; and transmit the second reference signal set to the second node using a second reference signal resource set on the second sub-band of the MIMO channel and / or during a second time interval on the MIMO channel, wherein the first node transmits the first and second reference signal sets to assist the second node in performing positioning measurements based on the joint processing of the first and second reference signal sets.

[0016] In one aspect, an apparatus for processing reference signals for positioning estimation on a multipath MIMO channel includes: means for communication of a second node, the means being configured to: receive from a first node a first set of reference signals on a first set of reference signal resources, wherein the first set of reference signal resources appears on a first subband of the MIMO channel and / or during a first time interval on the MIMO channel, and wherein each reference signal resource in the first set of reference signal resources utilizes at least a first MIMO precoder; and receive from the first node a second set of reference signals on a second set of reference signal resources, wherein the second set of reference signal resources appears on a second subband of the MIMO channel and / or during a second time interval on the MIMO channel, and wherein each reference signal resource in the second set of reference signal resources utilizes at least a second MIMO precoder; and means for processing of the second node, the means being configured to: identify at least one reference signal transmitted on the first set of reference signal resources and the second set of reference signal resources as following a LOS path between the second node and the first node; and perform a TDOA measurement by the second node based on the at least one reference signal.

[0017] In one aspect, a non-transient computer-readable medium storing computer-executable instructions for transmitting reference signals for positioning estimation over a multipath MIMO channel includes computer-executable instructions comprising: at least one instruction configuring a first reference signal resource set of a first reference signal set for transmitting a first reference signal set, wherein the first reference signal resource set occurs on a first subband of the MIMO channel and / or during a first time interval on the MIMO channel, and wherein each reference signal resource in the first reference signal resource set utilizes at least a first MIMO precoder; and at least one instruction configuring the first instruction node for transmitting a second reference signal resource set of a second reference signal set, wherein the second reference signal resource set occurs on a second subband of the MIMO channel and / or during a first time interval on the MIMO channel. During a second time interval, and wherein each reference signal resource in the second reference signal resource set utilizes at least a second MIMO precoder; instructs the first node to transmit at least one instruction of the first reference signal set to the second node using the first reference signal resource set on the first subband of the MIMO channel and / or during the first time interval on the MIMO channel; and instructs the first node to transmit at least one instruction of the second reference signal set to the second node using the second reference signal resource set on the second subband of the MIMO channel and / or during the second time interval on the MIMO channel, wherein the first node transmits the first reference signal set and the second reference signal set to assist the second node in performing positioning measurements based on the joint processing of the first reference signal set and the second reference signal set.

[0018] In one aspect, a non-transient computer-readable medium storing computer-executable instructions for transmitting reference signals for positioning estimation over a multipath MIMO channel includes computer-executable instructions comprising: instructing a second node to receive at least one instruction from a first node for a first set of reference signals on a first set of reference signal resources, wherein the first set of reference signal resources occurs on a first subband of the MIMO channel and / or during a first time interval on the MIMO channel, and wherein each reference signal resource in the first set of reference signal resources utilizes at least a first MIMO precoder; instructing the second node to receive at least one instruction from the first node for a second set of reference signals on a second set of reference signal resources, wherein the second set of reference signal resources occurs on a second subband of the MIMO channel and / or during a second time interval on the MIMO channel, and wherein each reference signal resource in the second set of reference signal resources utilizes at least a second MIMO precoder; instructing the second node to identify at least one reference signal transmitted on the first and second sets of reference signal resources as following a LOS path between the second node and the first node; and instructing the second node to perform a TDOA measurement based on the at least one reference signal.

[0019] Other objectives 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 attached diagram

[0020] A more complete understanding of the aspects described herein and their many accompanying advantages will be readily available when considered in conjunction with the following detailed description, which is given for illustrative purposes only and does not constitute any limitation, and wherein:

[0021] Figure 1 Exemplary wireless communication systems based on various aspects are explained.

[0022] Figure 2A and Figure 2B The example wireless network architecture is explained from various aspects.

[0023] Figure 3 Exemplary base stations and exemplary UEs in the access network are explained according to various aspects.

[0024] Figure 4 Exemplary wireless communication systems according to various aspects of this disclosure are explained.

[0025] Figure 5A This is a diagram illustrating the structure of an example LTE subframe sequence with PRS positioning timing.

[0026] Figure 5B This is a diagram illustrating an exemplary mapping from PRS to resource elements.

[0027] Figure 6 This is a graph showing the RF channel response at the UE over time according to various aspects of this disclosure.

[0028] Figure 7 This is a block diagram of an embodiment of a transmitter unit for precoding data for a multipath channel.

[0029] Figure 8 and Figure 9 An exemplary method for transmitting and processing reference signals for positioning estimation over a MIMO channel is described. Detailed description

[0030] The various aspects described herein generally relate to wireless communication systems, and more particularly to frequency / time selective precoding for positioning reference signals in 5G NR.

[0031] These and other aspects are disclosed in the following description and related drawings to illustrate specific examples in relation to the various exemplary aspects. Alternative aspects will be apparent to those skilled in the art upon reading this disclosure and can be constructed and practiced without departing from the scope or spirit of this disclosure. Furthermore, 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.

[0032] The term “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” need not be construed as superior to or better than other aspects. Similarly, the term “aspect” does not require all aspects to include the features, advantages, or modes of operation discussed.

[0033] The terminology used herein describes specific aspects only and should not be construed as limiting any aspect disclosed herein. As used herein, the singular forms “a,” “some,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Those skilled in the art will further understand that the terms “comprising,” “having,” “including,” and / or “containing,” as used herein, specify the presence of the stated 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.

[0034] Furthermore, the various aspects can be described as sequences of actions performed by elements, such as computing devices. Those skilled in the art will recognize that the various actions described herein can be performed by special-purpose circuitry (e.g., application-specific integrated circuits (ASICs)), by program instructions being executed by one or more processors, or by a combination of both. Additionally, the sequences of actions described herein can be considered to be fully implemented within any form of non-transitory computer-readable medium storing a corresponding set of computer instructions that, upon execution, will cause the associated processor to perform the functionality described herein. Thus, the various aspects described herein can be implemented in several different forms, all of which are contemplated to fall within the scope of the claimed subject matter. Furthermore, for each aspect described herein, a corresponding form of any such aspect can be described herein as, for example, "logic configured to perform the described actions" and / or other structural components configured to perform the described actions.

[0035] As used herein, the terms “user equipment” (or “UE”), “user terminal”, “client equipment”, “communication equipment”, “wireless equipment”, “wireless communication equipment”, “handheld device”, “mobile device”, “mobile terminal”, “mobile station”, “handheld device”, “access terminal”, “subscriber equipment”, “subscriber terminal”, “subscriber station”, “terminal”, and variations thereof may interchangeably refer to any suitable mobile or stationary device capable of receiving wireless communication and / or navigation signals. These terms are also intended to include devices that communicate with another device capable of receiving wireless communication and / or navigation signals (such as via short-range wireless, infrared, wired connections, or other connections), regardless of whether satellite signal reception, auxiliary data reception, and / or positioning-related processing occur at that device or at that other device. Furthermore, these terms are intended to include all devices, including wireless and wired communication devices capable of communicating with the core network via a radio access network (RAN), through which the UE can connect to external networks (such as the Internet) and other UEs. Of course, other mechanisms for connecting to the core network and / or the Internet are also possible for the UE, such as on a wired access network, a wireless local area network (WLAN) (e.g., based on IEEE 802.11), etc. The UE can be implemented using any of several types of devices, including but not limited to printed circuit (PC) cards, compact flash memory devices, external or internal modems, wireless or wired telephones, smartphones, tablets, tracking devices, asset tags, etc. The communication link through which the UE can signal to the RAN is called an uplink channel (e.g., reverse traffic channel, reverse control channel, access channel, etc.). The communication link through which the RAN can signal to the UE is called a downlink or forward link channel (e.g., paging channel, control channel, broadcast channel, forward traffic channel, etc.). As used herein, the term traffic channel (TCH) can refer to an uplink / reverse or downlink / forward traffic channel.

[0036] According to various aspects, Figure 1 An exemplary wireless communication system 100 has been described. The wireless communication system 100 (also referred to as a wireless wide area network (WWAN)) may include various base stations 102 and various UEs 104. Base stations 102 may include macrocells (high-power cellular base stations) and / or small cells (low-power cellular base stations), wherein macrocells may include evolved B-nodes (eNBs), wherein the wireless communication system 100 corresponds to an LTE network or a g-B-node (gNB), wherein the wireless communication system 100 corresponds to a 5G network or a combination of both, and small cells may include femtocells, picocells, microcells, etc.

[0037] The base stations 102 can collectively form a RAN and interface with an Evolved Packet Core (EPC) or Next Generation Core (NGC) via a backhaul link. Among other functions, base station 102 can also perform one or more of the following functions: transmitting user data, radio channel cryptography and decoding, integrity protection, header compression, mobility control functions (e.g., handover, 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 services, and delivery of alarm messages. Base stations 102 can communicate with each other directly or indirectly on a backhaul link 134 (e.g., via EPC / NGC), which can be wired or wireless.

[0038] Base station 102 can wirelessly communicate with UE 104. Each base station 102 can provide communication coverage for its respective geographical coverage area 110. On the one hand, although not in Figure 1 As shown, however, 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 base station 102. As used herein, depending on the context, the terms “cell” or “sector” may correspond to one of the multiple cells of base station 102 or base station 102 itself.

[0039] While the geographic coverage areas 110 of adjacent macrocells may partially overlap (e.g., in handover areas), some geographic coverage areas 110 may substantially overlap with larger geographic coverage areas 110. For example, a small cell base station 102' may have geographic coverage areas 110' that substantially overlap with the geographic coverage areas 110 of one or more macrocell base stations 102. A network that includes both small cells and macrocells may be referred to as a heterogeneous network. A heterogeneous network may also include home eNBs (HeNBs) that provide service to a restricted group known as a Closed Subscriber Group (CSG). The communication link 120 between base station 102 and UE 104 may include uplink (UL) (also known as reverse link) transmission from UE 104 to base station 102 and / or downlink (DL) (also known as forward link) transmission from base station 102 to UE 104. The communication link 120 may use MIMO antenna technologies, including spatial multiplexing, beamforming, and / or transmit diversity. These communication links may use one or more carriers. Carrier allocation can be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated to DL compared to UL).

[0040] The wireless communication system 100 may further include a wireless local area network (WLAN) access point (AP) 150 communicating with a WLAN station (STA) 152 via a communication link 154 in unlicensed spectrum (e.g., 5 GHz). When communicating in unlicensed spectrum, the WLAN STA 152 and / or WLAN AP 150 may perform a clear channel assessment (CCA) to determine the availability of the channel before communication.

[0041] Small cell base station 102' can operate in licensed and / or unlicensed spectrum. When operating in unlicensed spectrum, small cell base station 102' can employ LTE or 5G technology and use the same 5GHz unlicensed spectrum as used by WLAN AP150. Small cell base station 102' employing LTE / 5G in unlicensed spectrum can enhance access network coverage and / or increase access network capacity. LTE in unlicensed spectrum may be referred to as LTE Unlicensed (LTE-U), Licensed Assisted Access (LAA), or...

[0042] Extremely high frequency (EHF) is a portion of the electromagnetic spectrum that contains radio frequency (RF). EHF has a range of 30 GHz to 300 GHz and wavelengths between 1 mm and 10 mm. Radio waves in this band are referred to as millimeter waves. Near-mmW extends down to frequencies of 3 GHz and wavelengths of 100 mm. Ultra-high frequency (SHF) bands extend between 3 GHz and 30 GHz, and are also referred to as centimeter waves. Communication using mmW / near-mmW RF bands has high path loss and relatively short range. Wireless communication system 100 may further include an mmW base station 180, which can operate at mmW and / or near-mmW frequencies to communicate with UE 182. The mmW base station 180 can utilize beamforming 182 with UE 182 to compensate for the extremely high path loss and short range. Furthermore, it will be appreciated that in alternative configurations, one or more base stations 102 may also use mmW or near-mmW frequencies and beamforming for transmission. Accordingly, it will be understood that the foregoing explanations are merely illustrative and should not be construed as limiting the aspects disclosed herein.

[0043] The wireless communication system 100 may further 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 the example, UE190 has a D2D P2P link 192 with one of UEs 104 connected to one of base stations 102 (e.g., through which UE 190 indirectly obtains cellular connectivity), and a D2D P2P link 194 with a WLAN STA 152 connected to a WLAN AP 150 (through which UE 190 indirectly obtains WLAN-based Internet connectivity). In one example, D2D P2P links 192-194 can use any known D2D radio access technology (RAT) (such as LTE Direct (LTE-D), WiFi Direct (WiFi-D)). (etc.) to support.

[0044] According to various aspects, Figure 2A Example wireless network architecture 200 is explained. For example, NGC 210 can be functionally considered as control plane functions 214 (e.g., UE registration, authentication, network access, gateway selection, etc.) and user plane functions 212 (e.g., UE gateway functions, access to data networks, Internet Protocol (IP) routing, etc.), which operate collaboratively to form the core network. User plane interface (NG-U) 213 and control plane interface (NG-C) 215 connect gNB 222 to NGC 210, specifically to control plane functions 214 and user plane functions 212. In an additional configuration, eNB 224 can also connect to NGC 210 via NG-C 215 to connect to control plane functions 214, and via NG-U 213 to connect to NGC 210 to connect to user plane functions 212. Furthermore, eNB 224 can communicate directly with gNB 222 via backhaul connection 223. Accordingly, in some configurations, the new RAN 220 may have only one or more gNB 222s, while other configurations include one or more of eNB 224 and gNB 222. The gNB 222 or eNB 224 can be used with the UE 240 (e.g., Figure 1 The UE 240 can communicate with any UE depicted herein, such as UE 104, UE 182, UE 190, etc. Another optional aspect may include a location server 230 that can communicate with NGC 210 to provide location assistance to UE 240. Location server 230 may be implemented as multiple structurally separate servers, or alternatively, each may correspond to a single server. Location server 230 may be configured to support one or more location services for UE 240, which UE 240 can connect to via the core network, NGC 210, and / or via the Internet (not described). Furthermore, location server 230 may be integrated into a component of the core network, or alternatively, may be external to the core network.

[0045] According to various aspects, Figure 2BAnother example wireless network architecture 250 is described. For example, NGC 260 (also referred to as "5GC") can be functionally considered as a control plane function provided by Access and Mobility Management Function (AMF) / User Plane Function (UPF) 264 and a user plane function provided by Session Management Function (SMF) 262, which operate cooperatively to form the core network (i.e., NGC 260). User plane interface 263 and control plane interface 265 connect eNB 224 to NGC 260, specifically to SMF 262 and AMF / UPF 264, respectively. In an additional configuration, gNB 222 can also connect to NGC 260 via control plane interface 265 to AMF / UPF 264 and user plane interface 263 to SMF 262. Furthermore, eNB 224 can communicate directly with gNB 222 via backhaul connection 223, whether or not it has direct gNB connectivity to NGC 260. In some configurations, the new RAN 220 may have only one or more gNB 222s, while other configurations include one or more of both eNB 224 and gNB 222. The gNB 222 or eNB 224 can be used with UE 204 (e.g., Figure 1 The base station of the new RAN 220 communicates with the AMF side of the AMF / UPF 264 via the N2 interface and with the UPF side of the AMF / UPF 264 via the N3 interface.

[0046] The AMF's functions include registration management, connection management, reachability management, mobility management, lawful interception, transmission of Session Management (SM) messages between UE 204 and SMF 262, transparent proxy service for routing SM messages, access authentication and access authorization, transmission of Short Message Service (SMS) messages between UE 204 and the Short Message Service Function (SMSF) (not shown), and Security Anchor Functionality (SEAF). The AMF also interacts with the Authentication Server Function (AUSF) (not shown) and UE 204, and receives an intermediate key established as a result of the UE 204 authentication process. In cases where authentication is based on the UMTS (Universal Mobile Telecommunications System) Subscriber Identity Module (USIM), the AMF retrieves security material from the AUSSF. The AMF's functions also include Security Context Management (SCM). The SCM receives a key from the SEAF, which is used by the SCM to derive a key that varies depending on the access network. The functionality of AMF also includes location service management for regulatory services, transmission of location service messages between UE 204 and Location Management Function (LMF) 270 and between the new RAN 220 and LMF 270, Evolved Packet System (EPS) bearer identifier allocation for interoperability with EPS, and UE 204 mobility event notification. Furthermore, AMF also supports functionality for non-3GPP access networks.

[0047] The functions of the UPF include: acting as an anchor point for intra / inter-RAT mobility (where applicable), acting as an external Protocol Data Unit (PDU) session point interconnected to a data network (not shown), providing packet routing and forwarding, packet inspection, user plane policy rule enforcement (e.g., gating, redirection, traffic steering), lawful interception (user plane collection), traffic usage reporting, quality of service (QoS) handling for the user plane (e.g., UL / DL rate enforcement, reflective QoS marking in DL), UL traffic verification (service data flow (SDF) to QoS flow mapping), transport-level packet marking in UL and DL, DL packet buffering and DL data notification triggering, and sending and forwarding one or more "end markers" to the source RAN node.

[0048] The functions of SMF 262 include session management, UE Internet Protocol (IP) address allocation and management, selection and control of user plane functions, configuration of traffic guidance at the UPF for routing traffic to the correct destination, control of policy enforcement and QoS, and downlink data notification. The interface through which SMF 262 communicates with the AMF side of AMF / UPF 264 is called the N11 interface.

[0049] Another optional aspect may include an LMF270 that can communicate with NGC 260 to provide location assistance to UE 204. 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 extending across multiple physical servers, etc.), or alternatively, each may correspond to a single server. The LMF 270 may be configured to support one or more location services for UE 204, and UE 240 may connect to the LMF 270 via the core network, NGC 260, and / or via the Internet (not explained).

[0050] According to various aspects, Figure 3 An exemplary base station 310 (e.g., eNB, gNB, small cell AP, WLAN AP, etc.) communicating with an exemplary UE 350 in a wireless network according to various aspects of this disclosure is described. Base station 310 may correspond to any base station described herein. In the DL, IP packets from the core network (NGC 210 / EPC 260) may be provided to the controller / processor 375. The controller / processor 375 implements functionality for the Radio Resource Control (RRC) layer, Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, and Media Access Control (MAC) layer. The controller / processor 375 provides RRC layer functionality associated with broadcast system information (e.g., Master Information Block (MIB), System Information Block (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 of UE measurement reports; PDCP layer functionality associated with header compression / decompression, security (cryptography, cryptographic decoding, integrity protection, integrity verification), and handover support functions; RLC layer functionality associated with upper-layer packet data unit (PDU) delivery, error correction via Automatic Repeat Request (ARQ), concatenation, segmentation and reassembly of RLC service data units (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, scheduling information reporting, error correction, priority handling, and logical channel priority ordering.

[0051] Transmit (TX) processor 316 and 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 transport channel, forward error correction (FEC) encoding / decoding of the transport channel, interleaving, rate matching, mapping to the physical channel, modulation / demodulation of the physical channel, and MIMO antenna processing. TX processor 316 processes 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 encoded and modulated symbols can then be split into parallel streams. Each stream can then be mapped to an orthogonal frequency division multiplexing (OFDM) subcarrier, multiplexed with a reference signal (e.g., a pilot) in the time and / or frequency domains, and subsequently 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 generate multiple spatial streams. Channel estimates from channel estimator 374 can be used to determine coding and modulation schemes and for spatial processing. These channel estimates can be derived from reference signals and / or channel condition feedback transmitted by UE 350. Each spatial stream can then be provided to the TXMIMO processor (hereinafter referred to as...). Figure 7 (Further description), and from which it is provided via separate transmitters 318a to one or more different antennas 320. Each transmitter 318a can use a corresponding spatial stream to modulate an RF carrier for transmission.

[0052] At UE 350, each receiver 354a receives signals via its respective antenna 352. Each receiver 354a recovers the information modulated onto the RF carrier and provides this information to the RX processor 356. The TX processor 368 and RX processor 356 implement Layer-1 functionality associated with various signal processing functions. The RX processor 356 can perform spatial processing on this information to recover any spatial stream destined for UE 350. If multiple spatial streams are destined for UE 350, they can be combined by the RX processor 356 into a single OFDM symbol stream. The RX processor 356 then uses a Fast Fourier Transform (FFT) to transform the OFDM symbol stream from the time domain to the frequency domain. This frequency domain signal comprises a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, along with the reference signal, are recovered and demodulated by determining the signal constellation points most likely to be transmitted by base station 310. These soft decisions can be based on a channel estimate calculated by channel estimator 358. These soft decisions are then decoded and deinterleaved to recover the original data and control signals transmitted by base station 310 over the physical channel. These data and control signals are then provided to controller / processor 359, which implements layer-3 and layer-2 functionality.

[0053] The controller / processor 359 may be associated with a memory 360 that stores program code and data. The memory 360 may be referred to as a non-transient computer-readable medium. In the UL, the controller / processor 359 provides demultiplexing between transport and logical channels, packet reassembly, cipher decoding, header decompression, and control signal processing to recover IP packets from the core network. The controller / processor 359 is also responsible for error correction.

[0054] Similar to the functionality described in conjunction with DL transmissions performed by base station 310, controller / processor 359 provides RRC layer functionality associated with system information (e.g., MIB, SIB) capture, RRC connectivity, and measurement reporting; PDCP layer functionality associated with header compression / decompression and security (cryptography, cryptographic decoding, integrity protection, integrity verification); RLC layer functionality associated with upper-layer PDU delivery, error correction via 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 onto transport blocks (TBs), demultiplexing MAC SDUs from TBs, scheduling information reporting, error correction via Hybrid Automatic Repeat Request (HARQ), priority handling, and logical channel priority ordering.

[0055] The channel estimate derived by the channel estimator 358 from the reference signal or feedback transmitted by the base station 310 can be used by the TX processor 368 to select appropriate coding and modulation schemes and facilitate spatial processing. The spatial stream generated by the TX processor 368 can be provided to an optional TX MIMO processor (described further below) and from there to different antennas 352 via separate transmitters 354b. Each transmitter 354b can modulate an RF carrier with the corresponding spatial stream for transmission. In one aspect, the transmitters 354b and receivers 354a can be one or more transceivers, one or more discrete transmitters, one or more discrete receivers, or any combination thereof.

[0056] UL transmissions are processed at base station 310 in a manner similar to that described in conjunction with the receiver function at UE 350. Each receiver 318b receives signals via its respective antenna 320. Each receiver 318b recovers the information modulated onto the RF carrier and provides that information to the RX processor 370. In one aspect, transmitter 318a and receiver 318b can be one or more transceivers, one or more discrete transmitters, one or more discrete receivers, or any combination thereof.

[0057] The controller / processor 375 may be associated with a memory 376 that stores program code and data. The memory 376 may be referred to as a non-transient computer-readable medium. In the UL, the controller / processor 375 provides demultiplexing between transport and logical channels, packet reassembly, cipher decoding, header decompression, and control signal processing to recover IP packets from the UE 304. IP packets from the controller / processor 375 can be provided to the core network. The controller / processor 375 is also responsible for error correction.

[0058] Figure 4 An exemplary wireless communication system 400 according to various aspects of this disclosure has been described. Figure 4 In the example, UE404 (which can correspond to the above regarding...) Figure 1 Any UE described (e.g., UE 104, UE 182, UE 190, etc.) is attempting to calculate an estimate of the location of UE 404, or assisting another entity (e.g., a base station or core network component, another UE, a location server, a third-party application, etc.) in calculating an estimate of the location of UE 404. UE 404 can use RF signals and standardized protocols for modulating RF signals and exchanging information packets to wirelessly communicate with multiple base stations 402a-d (collectively referred to as base stations 402), which may correspond to... Figure 1 Any combination of base stations 102 or 180 and / or WLAN AP 150. By extracting different types of information from the exchanged RF signals and utilizing the layout of the wireless communication system 400 (i.e., the location, geometry, etc. of the base stations 402), the UE 404 can determine its location, or assist in determining its location in a predefined reference coordinate system. In one aspect, the UE 404 can use a two-dimensional coordinate system to specify its location; however, the aspects disclosed herein are not limited to this, and it is also applicable to using a three-dimensional coordinate system to determine location when additional dimensions are desired. Furthermore, although Figure 4 The explanation describes one UE404 and four base stations 402, but as will be understood, there may be more UEs 404 and more or fewer base stations 402.

[0059] As used herein, "network node" can refer to base station 402, the cell of base station 402, the remote radio head, or the antenna of base station 402, wherein the antenna of base station 402 is located in a position different from the location of base station 402 itself or the location of any other network entity capable of transmitting reference RF signals. Furthermore, as used herein, "node" can refer to a network node or a UE.

[0060] The term "base station" can refer to a single physical transmission point that may or may not be located in the same place. For example, when the term "base station" refers to a single physical transmission point, that physical transmission point can be a base station antenna corresponding to a cell of a base station (e.g., base station 402). When the term "base station" refers to multiple physical transmission points located in the same place, that physical transmission point can be an antenna array of a base station (e.g., as in a MIMO system or where beamforming is used at the base station). When the term "base station" refers to multiple physical transmission points not located in the same place, the physical transmission points can 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 headend (RRH) (a remote base station connected to a serving base station). Alternatively, physical transmission points not located in the same place can be the serving base station from which a measurement report is received from a UE (e.g., UE 404) and neighboring base stations from which the UE is measuring its reference RF signal. Therefore, Figure 4 The explanation details one aspect of how base stations 402a and 402b form a DAS / RRH 420. For example, base station 402a can be the serving base station of UE 404, and base station 402b can be a neighboring base station of UE 404. Thus, base station 402b can be the RRH of base station 402a. Base stations 402a and 402b can communicate with each other on a wired or wireless link 422.

[0061] A location server (e.g., location server 230) may send auxiliary data to UE 404, which includes: identifiers of one or more neighboring cells of base station 402, and configuration information for reference RF signals transmitted by each neighboring cell. Alternatively, the auxiliary data may be derived directly from each base station 402 itself (e.g., in periodically broadcast overhead messages, etc.). Alternatively, UE 404 may detect neighboring cells of base station 402 itself without using auxiliary data. As further described herein, UE 404 (e.g., based in part on auxiliary data, if provided) may measure and (optionally) report its own RTT with individual network nodes. Using these measurements and the known locations of the measured network nodes (i.e., base stations 402 or antennas(s) that transmit the reference RF signals measured by UE 404), UE 404 or the location server may determine the distance between UE 404 and the measured network nodes, and thereby calculate the location of UE 404.

[0062] In this document, the term "location estimate" is used to refer to an estimate of the location of a UE (e.g., UE 404), which may be geographical (e.g., may include latitude, longitude, and possibly altitude) or municipal (e.g., may include street address, 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 within a building), or landmark (such as a town square)). Location estimates may also be referred to as "orientation," "location," "lock," "location lock," "location estimate," "lock estimate," or some other term. The method of obtaining a location estimate may generally be referred to as "location," "addressing," or "location lock." A specific solution used to obtain a location estimate may be referred to as a "location solution." A specific method used as part of a location solution to obtain a location estimate may be referred to as a "location method" or "location approach." Location estimates may include expected errors or uncertainties (e.g., by including the area or volume expected to include the location along with a specified or default confidence level).

[0063] To support location estimation, base stations 402 can be configured to broadcast reference RF signals (e.g., Position Reference Signal (PRS), Cellular Reference Signal (CRS), Channel State Information Reference Signal (CSI-RS), Narrowband Reference Signal (NRS), synchronization signal, etc.) to each UE 404 within their coverage area, enabling UE 404 to measure the RTT between UE 404 and the transmitting base station 402. Generally, the beam of interest used for RTT measurement is a LOS beam or a beam that triggers the shortest RF path (which can be an LOS beam or an NLOS beam following the shortest path to the receiver).

[0064] However, RF signals do not only travel along the LOS / shortest NLOS path between the transmitter and receiver, but also along several other paths because the RF signal spreads out from the transmitter and is reflected by other objects (such as hills, buildings, water, etc.) on its way to the receiver. Therefore, Figure 4 The document explains several LOS paths 410 and several NLOS paths 412 between base station 402 and UE 404. Specifically, Figure 4 The explanation states that base station 402a transmits on LOS path 410a and NLOS path 412a, base station 402b transmits on LOS path 410b and two NLOS paths 412b, base station 402c transmits on LOS path 410c and NLOS path 412c, and base station 402d transmits on two NLOS paths 412d. Figure 4As explained herein, each NLOS path 412 is reflected by an object 430 (e.g., a building). As will be understood, each LOS path 410 and NLOS path 412 transmitted by base station 402 may be transmitted by different antennas of base station 402 (e.g., as in a MIMO system), or may be transmitted by the same antenna of base station 402 (thus explaining the propagation of the RF signal). Furthermore, as used herein, the term "LOS path" refers to the shortest path between the transmitter and receiver, and may not be the actual LOS path but rather the shortest NLOS path.

[0065] In one aspect, one or more base stations 402 may be configured to use beamforming to transmit RF signals. In this case, some available beams may focus the transmitted RF signal along LOS path 410 (e.g., these beams produce the highest antenna gain along the LOS path), while other available beams may focus the transmitted RF signal along NLOS path 412. A beam with high gain along a particular path and thus focusing the RF signal along that path may still cause a certain RF signal to propagate along other paths; the strength of that RF signal naturally depends on the beam gain along those other paths. An “RF signal” includes electromagnetic waves that transmit information through the space between the transmitter and receiver. As used herein, the transmitter may transmit a single “RF signal” or multiple “RF signals” to the receiver. However, as further described below, due to the propagation characteristics of each RF signal through a multipath channel, the receiver may receive multiple “RF signals” corresponding to each transmitted RF signal.

[0066] When base station 402 uses beamforming to transmit RF signals, the beam of interest for data communication between base station 402 and UE 404 will be the beam carrying the RF signal arriving at UE 404 with the highest signal strength (e.g., indicated by received signal received power (RSRP) or SINR in the presence of directional interference signals), while the beam of interest for location estimation will be the beam carrying the RF signal that triggers the shortest path or LOS path (e.g., LOS path 410). In some frequency bands and for commonly used antenna systems, these beams will be the same. However, in other frequency bands (such as mmW), where a large number of antenna elements can typically be used to create a narrow transmit beam, they may not be the same beam. That is, in some cases, the signal strength of the RF signal on LOS path 410 may be weaker (e.g., due to obstacles) than the signal strength of the RF signal on NLOS path 412, where the RF signal arrives later on NLOS path 412 due to propagation delay.

[0067] Figure 5AThe structure of an example LTE subframe sequence 500 with PRS positioning timing is shown. Subframe sequence 500 can be applied to the broadcast of PRS signals from a base station (e.g., any of the base stations described above) or other network nodes. Although Figure 5A An example of a subframe sequence for LTE is provided, but similar subframe sequence implementations can be implemented for other communication technologies / protocols such as 5G and NR. Figure 5A In this representation, time is horizontally (e.g., on the X-axis), where time increases from left to right, while frequency is vertically (e.g., on the Y-axis), where frequency increases (or decreases) from bottom to top. Figure 5A As shown, the downlink and uplink LTE radio frames 510 can each have a duration of 10 milliseconds (ms). For downlink frequency division duplex (FDD) mode, in the illustrated example, radio frame 510 is organized into ten subframes 512, each with a duration of 1 ms. Each subframe 512 includes two time slots 514, each time slot having a duration of, for example, 0.5 ms.

[0068] In the frequency domain, the available bandwidth can be divided into evenly spaced orthogonal subcarriers 516 (also referred to as “frequency modulation” or “frequency slots”). For example, for a normal-length cyclic prefix (CP) using, for example, a 15 kHz interval, the subcarriers 516 can be grouped into a group with twelve (12) subcarriers. A resource (represented as a block of subframe 512) of one OFDM symbol length in the time domain and one subcarrier in the frequency domain is called a resource element (RE). Each group of 12 subcarriers 516 and 14 OFDM symbols is called a resource block (RB) or physical resource block (PRB), and in the above example, the number of subcarriers in a resource block can be written as For a given channel bandwidth, the number of available resource blocks on each channel 522 (also referred to as transmission bandwidth configuration 522) is expressed as: For example, for a 3MHz channel bandwidth in the example above, the number of available resource blocks on each channel 522 is determined by... Provided.

[0069] Base stations can be based on and Figure 5A The frame configurations shown are similar or identical to those used to transmit radio frames (e.g., radio frame 510) or other physical layer signaling sequences that support PRS signals (i.e., downlink (DL) PRS), which can be measured and used for UE (e.g., any of the UEs mentioned above) location determination. Other types of wireless nodes in the wireless communication network (e.g., DAS, RRH, UE, AP, etc.) can also be configured to transmit to... Figure 5A The PRS signal is configured in a manner similar to (or the same as) the one described in the text.

[0070] PRS, already defined in 3GPP LTE Release 9 and later, can be transmitted in the wireless communication network by the base station after proper configuration (e.g., by an Operations and Maintenance (O&M) server). PRS can be transmitted in specific positioning subframes grouped into positioning times. For example, in LTE, PRS positioning times can include a number of N. PRS N consecutive positioning subframes, of which the number is N PRS The value can be between 1 and 160 (e.g., values ​​1, 2, 4, and 6, as well as other values). The PRS positioning timing for cells supported by the base station can be periodically scheduled at intervals (consisting of a number of T). PRS The occurrence is indicated by a millisecond (or subframe) interval, where T PRS It can be equal to 5, 10, 20, 40, 80, 160, 320, 640, or 1280 (or any other suitable value). As an example, Figure 5A The periodicity of positioning timing was explained, where N PRS It equals 4 (518), and T PRS Greater than or equal to 20 (520). In some respects, T PRS It can be measured in terms of the number of subframes between the start of each consecutive positioning timing.

[0071] Within each positioning time, PRS can be transmitted at constant power. PRS can also be transmitted at zero power (i.e., silenced). Silencing periodically scheduled PRS transmissions can be useful when PRS signals from different cells overlap by occurring at the same or nearly the same time. In this case, PRS signals from some cells can be silenced, while PRS signals from other cells are transmitted (e.g., at constant power). Silencing can assist the UE in signal acquisition and Time of Arrival (TOA) and RSTD measurements of non-silenced PRS signals (by avoiding interference from already silenced PRS signals). Silencing can be considered as not transmitting PRS for a given positioning time for a specific cell. A bit string can be used to signal the UE (e.g., using the LTE Positioning Protocol (LPP)) a silence mode (also known as a silence sequence). For example, in the bit string signaled to indicate the silence mode, if the bit at position j is set to '0', the UE can infer that the PRS is silenced for the j-th positioning time.

[0072] To further improve the audibility of the PRS, the positioning subframe can be a low-interference subframe transmitted in the absence of a user data channel. As a result, in an ideally synchronized network, the PRS may be interfered with by the PRS of other cells with the same PRS pattern index (i.e., the same frequency shift), but not by interference from data transmission. Frequency shift is, for example, defined in LTE as a function of the PRS ID for the cell or other transport point (TP) (denoted as...). Or, in the absence of an assigned PRS ID, a function for the Physical Cell Identifier (PCI) (denoted as...). ), which results in an effective frequency reuse factor of six (6).

[0073] To further improve the audibility of the PRS (e.g., when the PRS bandwidth is limited to, for example, only 6 resource blocks corresponding to a 1.4 MHz bandwidth), the frequency band for coherent PRS positioning moments (or coherent PRS subframes) can be changed via frequency hopping in a known and predictable manner. Additionally, a cell supported by a base station can support more than one PRS configuration, where each PRS configuration may include a specific frequency shift (vshift), a specific carrier frequency, a specific bandwidth, a specific code sequence, and / or a specific number of subframes (N) per positioning moment. PRS ) and specific periodicity (T) PRS The specific sequence of PRS positioning timing. In some implementations, one or more PRS configurations supported in a cell can be used for directional PRS and can subsequently have additional specific characteristics (such as specific transmission direction, specific horizontal angle range, and / or specific vertical angle range). Further enhancements to PRS can also be supported by the base station.

[0074] To assist in the positioning operation, a location server (e.g., location server 230) can provide the UE with OTDOA auxiliary data for a "reference cell" and one or more "neighboring cells" or "adjacent cells" relative to that "reference cell". For example, the auxiliary data may provide the center channel frequency of each cell, various PRS configuration parameters (e.g., N...). PRS T PRS The PRS-based location data includes: silent sequence, frequency hopping sequence, PRS ID, PRS bandwidth, global cell ID, PRS signal characteristics associated with directional PRS, and / or other cell-related parameters applicable to OTDOA or some other location method. PRS-based location by the UE can be facilitated by indicating the serving cell for the UE in the OTDOA auxiliary data (e.g., where a reference cell is indicated as the serving cell).

[0075] In some cases, OTDOA auxiliary data may also include "expected RSTD" parameters along with uncertainties to those parameters. These "expected RSTD" parameters provide the UE with information about the RSTD value the UE expects to measure at its current location between the reference cell and each neighboring cell. The expected RSTD, along with the associated uncertainties, can define a search window for the UE to expect to measure RSTD values ​​within that location. OTDOA auxiliary information may also include PRS configuration information parameters that allow the UE to determine when the PRS positioning timing occurs relative to the PRS positioning timing for the reference cell on signals received from each neighboring cell, and to determine the PRS sequence transmitted from each cell in order to measure the signal TOA or RSTD.

[0076] The location of the UE can be calculated (e.g., by the UE or a location server) using RSTD measurements, known absolute or relative transmission timing for each cell, and known locations of the physical transmit antennas(s) of the radio nodes for the reference cell and neighboring cells. More specifically, the RSTD of the neighboring cell k relative to the reference cell Ref can be given as (TOA... k –TOA Ref The TOA value can be measured modulo a subframe duration (1 ms) to remove the influence of measuring different subframes at different times. TOA measurements for different cells can then be converted into RSTD measurements (e.g., as defined in 3GPP TS 36.214 entitled "Physical Layer; Measurements") and sent by the UE to the location server. The UE's location can be determined using (i) RSTD measurements, (ii) known absolute or relative transmission timing for each cell, (iii) known locations of the physical transmit antennas used for reference cells and adjacent cells, and / or (iv) directional PRS characteristics (such as transmission direction).

[0077] In LTE, "Antenna Port 6" is used to transmit PRS with specific bandwidth and modes. The mapping of PRS to Resource Elements (REs) is in... Figure 5B The diagram shows a normal cyclic prefix and one or two transmit antenna ports. Figure 5B The subframe 512, with 12 subcarriers on 14 OFDM symbols, was explained. Figure 5B Each frame in the subframe indicates a RE with a frequency domain index k and a time domain index l. The frame marked "R6" in subframe 512 indicates a PRS RE.

[0078] In LTE, antenna ports do not correspond to physical antennas, but are logical entities distinguished by their reference signal sequences. Therefore, multiple antenna port signals can be transmitted on a single transmit antenna, and a single antenna port can be extended across multiple transmit antennas. However, in some cases (such as MIMO systems), each antenna port signal can be transmitted on a separate physical antenna to create spatial diversity across paths. Table 1 shows the mapping between the types of downlink LTE reference signals and the antenna ports they use. As shown in Table 1, the PRS in LTE uses antenna port 6.

[0079]

[0080]

[0081] Table 1

[0082] Reference Figure 5B The UE can jointly process all REs on the bandwidth and perform an inverse Fourier transform to convert the received signal to the time domain, thereby identifying the earliest path on the channel. The UE creates a Channel Energy Response (CER), the curve of which is shown in Figure 600. Figure 6 The earliest peak value was explained and identified. For example... Figure 6 As explained, the UE detects a first CER peak at ToA1, a second CER peak at ToA2, and a third CER peak at ToA3. The first CER peak detected at ToA1 corresponds to the earliest arriving reference RF signal. Therefore, the received reference RF signal corresponding to the CER peak at ToA1 is assumed to follow the LOS path.

[0083] ToAT at the UE for the shortest path from cell i i It is represented as:

[0084]

[0085] Where τ i It is the sum of the transmission time, NLOS transmission time, and UE timing measurement noise from cell i, D i It is the position (q) i Let q be the Euclidean distance between cell i at location (p) and UE at location (p), and let c be the speed of light in air (i.e., 299,700 km / s). We can assume the cell location q... i Known from the cellular information database, T can be estimated using PRS. i .

[0086] The following is the equation used to calculate Euclidean distance:

[0087]

[0088] Where D is the distance between two points on the Earth's surface, and R is the Earth's radius (i.e., 6371 km). and β1 and β2 are the latitude of the first point (in radians) and the latitude of the second point (in radians), respectively, and β1 and β2 are the longitude of the first point (in radians) and the latitude of the second point (in radians), respectively.

[0089] As mentioned above, 5G NR implementations are designed to significantly enhance the spectral efficiency of mobile communications compared to current 4G / LTE standards. Furthermore, signaling efficiency should be improved and latency significantly reduced compared to current standards. Specifically, several design goals exist for the positioning reference signal (sometimes called the navigation reference signal (NRS)) in 5G. For example, the NRS should allow the receiver (e.g., the UE) to take accurate measurements robust to multipath. The NRS should be able to provide navigation and positioning support (such as range, pseudorange, and angle measurements for positioning, and Doppler measurements for velocity estimation and navigation). Another design goal is that the NRS should also have a uniform and independent signal structure, allowing independence of the cyclic prefix (CP), antenna port number, and native symbol length, which can be supported by service multiplexing. Additionally, only the NRS should be permitted within the NRS envelope, i.e., it should not be mixed with CRS, tracking reference signal (TRS), primary synchronization signal (PSS), secondary synchronization signal (SSS), physical broadcast channel (PBCH), etc. Another design goal is to provide a high level of orthogonality / isolation between cells in the NRS, which will help alleviate the "near-far" problem (the receiver needs to be able to distinguish between near-end and far-end transmitters; however, the near-end transmitter may outpower the far-end transmitter, especially when they operate on the same channel, making it difficult or impossible for the receiver to receive the far-end transmitter). Therefore, the NRS should provide time-frequency orthogonality, code isolation, and antenna mode isolation. Yet another design goal is for the NRS to require low power consumption at the receiver.

[0090] As mentioned above, to support location estimation in terrestrial wireless networks, the UE can be configured to measure and report the OTDOA or RSTD between reference RF signals (e.g., PRS, NRS, etc.) received from two or more network nodes (e.g., different base stations or different transmission points belonging to the same base station (e.g., antennas)). For OTDOA-based positioning to be accurate, the UE needs to be able to accurately estimate the LOS, or earliest path, of the channel. However, due to obstructions (e.g., hills, buildings, water, etc.), RF signals on LOS paths may be received with significantly lower power compared to RF signals on other NLOS paths, and are therefore essentially "hidden" from the UE. Therefore, the UE may mistakenly identify one of these NLOS paths as a LOS path.

[0091] To better distinguish between LOS and NLOS paths, this disclosure provides techniques for introducing frequency and / or time diversity into a reference RF signal used for positioning, such as the NRS in 5G NR. In one aspect, the reference RF signal can be transmitted with a different MIMO precoder in each frequency subband or in each time interval, allowing the transmitter (e.g., base station) to adjust the CER measured at the receiver (e.g., UE) to attempt to make detection of the earliest path of the channel easier and more robust. Using a frequency-selective precoder can result in smoothing strong NLOS paths and making LOS paths easier to detect. More specifically, if the precoder in the frequency domain is adjusted, the corresponding time-domain impulse response of the channel will be convolved with the time-domain impulse response of the precoder. This can result in NLOS paths being smoothed out to a greater extent than LOS paths would be smoothed out. Therefore, NLOS paths may not be persistent when the precoder is adjusted. The receiver can process each measurement independently within a constant precoder frequency / time region and maintain tracking of the dominant RF signal path.

[0092] In conventional single-stream RF signal transmission, the same RF signal is transmitted from each transmit antenna with appropriate weighting (phase and gain) to maximize signal power at the receiver. "Precoding" is a technique that determines and applies appropriate weighting to the RF signal stream based on the channel conditions between the transmitter and receiver. Specifically, the transmitter estimates the channel conditions between itself and the receiver and determines the weighting for each transmit antenna based on these estimates. In this way, precoding reduces the impact of communication channel corruption.

[0093] Figure 7 This is a block diagram of an exemplary transmitter 700 for precoding data for a multipath channel according to various aspects of this disclosure. Transmitter 700 may correspond to... Figure 3The transmitter portion of base station 310 or UE 350. Among other components, transmitter 700 includes TX processor 710 (which may correspond to TX processor 316 or TX processor 368), which receives and processes traffic and pilot data to provide (up to) N T A precoded symbol stream; and a TX MIMO processor 720, which pre-conditions the precoded symbol stream to provide (up to) N T Each pre-conditioned code stream.

[0094] exist Figure 7 In the example, the TX processor 710 includes a symbol mapping element 716 and a precoder 718.

[0095] Symbol mapping element 716 receives pilot data and multiplexes the pilot data with a scrambled reference RF signal sequence, and further, performs symbol mapping on the multiplexed data according to one or more modulation schemes to provide modulation symbols. Individual modulation schemes may be used for each data stream or for each group of one or more data streams. Alternatively, a shared modulation scheme may be used for all data streams. Symbol mapping for each data stream can be achieved by: (1) grouping the multiplexed data bit set to form non-binary symbols; and (2) mapping each non-binary symbol to a point in the signal constellation corresponding to the modulation scheme selected for that data stream. Each mapped signal point corresponds to a modulation symbol. Symbol mapping element 716 provides a modulation symbol vector s(n) for each symbol period n, where the number of modulation symbols in each vector is equal to the number of spatial sub-channels to be used for that symbol period. Therefore, symbol mapping element 716 provides (up to) N T A modulation symbol stream (i.e., a sequence of modulation symbol vectors, wherein each vector comprises at most N) T (One modulation symbol).

[0096] To perform precoding at transmitter 700, the response of the MIMO channel can be estimated (e.g., via channel estimator 374 or channel estimator 358) and used to precode the modulated symbols and further pre-condition the precoded symbols before transmission over the MIMO channel. In FDD systems, the downlink and uplink are allocated different frequency bands, and the channel responses for the downlink and uplink may not be sufficiently correlated. For FDD systems, the channel response can be estimated at the receiver and transmitted back to the transmitter. However, in time-division duplex (TDD) systems, the downlink and uplink share the same frequency band in a time-division multiplexed manner, and there may be a high correlation between the downlink and uplink channel responses. Therefore, for TDD systems, transmitter 700 can estimate the uplink channel response (e.g., based on the pilot transmitted on the uplink by the receiver system) and derive the downlink channel response by taking into account the differences between the transmit and receive antenna arrays and front-end processing. However, in some cases, an estimate of the MIMO channel available for performing MIMO precoding may not be available. Instead, a predetermined or pseudo-random precoding choice can be used. For example, as further described herein, a precoder granularity, a small-delay cyclic delay diversity (SDCDD) parameter, a pseudo-random seed, a precoder cyclic ordering, or a precoder cyclic set can be used.

[0097] Precoder 718 receives and precodes the modulated symbol stream s(n) to provide a precoded symbol stream c(n). As further described herein, when the RF signal to be transmitted is a reference signal, precoder 718 can precode the reference signal for different subbands and / or for different time intervals. That is, different resources carrying the reference RF signal can use different MIMO precoders and therefore appear to be transmitted on different antenna ports. TX MIMO processor 720 then performs MIMO processing on the precoded symbol stream c(n) to orthogonalize these symbol streams at the receiver system (e.g., UE 350). As mentioned above, MIMO processing can be performed in the time domain or the frequency domain.

[0098] Convolutional unit 722 receives and preconditions the precoded symbol stream c(n) using a pulse shaping matrix (e.g., convolving the precoded symbol stream c(n) with the pulse shaping matrix) to derive the transmitted signal vector x(n). Each element of the transmitted signal vector x(n) corresponds to the preconditioned symbol stream to be transmitted on the corresponding transmit antenna 732 (which may correspond to transmit antenna 320 or transmit antenna 352). T A pre-conditioned symbol stream (i.e., a sequence of pre-conditioned symbol vectors, where each vector includes up to N...) TThe pre-conditioned code (N) is also labeled as N T The signal transmitted by each location. N T A pre-conditioned symbol stream is provided to transmitter 730 (which may correspond to transmitter 318a or transmitter 354b) and processed to derive N. T A modulated signal, which is then from N T One antenna 732 transmits data.

[0099] As mentioned above, this disclosure provides techniques for selectively precoding reference RF signals (such as NRS in 5G NR) used for positioning to introduce frequency and / or time diversity. As mentioned above, in LTE, the PRS is transmitted on antenna port 6, so each PRS will have the same MIMO precoder. However, in the techniques of this disclosure, the transmitter (e.g., TX processor 710) can configure the reference RF signal resources for different subbands and / or different time intervals so that it appears as if they are transmitted on different antenna ports.

[0100] As used in this article, the reference RF signal "resource" is a time-frequency grid (e.g., Figure 5A and 5B The reference RF signal resource (as explained in the text) is the set of resource elements carrying the reference RF signal in the subframe. For example, in LTE, the reference RF signal resource for PRS will be the resource element carrying the PRS in the subframe (in the text). Figure 5B (marked as "R6" in the original text). Therefore, each resource element of the reference RF signal resource carries a reference RF signal. The "set" of reference RF signal resources refers to the set of such resource elements that carry reference RF signals.

[0101] On one hand, each reference RF signal resource or set of reference RF signal resources can use a different MIMO precoder and therefore appear to be transmitted on a different antenna port than other reference RF signal resources or sets of reference RF signal resources. Alternatively, each resource element of a reference RF signal resource can use a different MIMO precoder. The MIMO precoder can be different for each frequency subband and / or each time interval in which a reference RF signal resource(set) is configured. Because the MIMO precoder is different for each reference RF signal resource or set of reference RF signal resources, the receiver (e.g., UE) cannot infer that a given reference RF signal resource(set) is being transmitted on the same antenna port or using the same MIMO precoder as another reference RF signal resource(set), unless they are being transmitted on the same subband or in the same time interval. The receiver can process all reference RF signals in the reference RF signal resource(set) to determine which signal follows the LOS path.

[0102] As an example, the four reference RF signal resources in the first set can carry four reference RF signals, which, from the receiver's perspective, have been encoded by a first antenna port or a first MIMO precoder. The four reference RF signal resources in the second set can carry four reference RF signals, which, from the receiver's perspective, have been encoded by different antenna ports or different MIMO precoders. As another example, the first reference RF signal resource can have multiple resource elements carrying reference RF signals, each of which, from the receiver's perspective, has been encoded by a different antenna port or a different MIMO precoder. The second reference RF signal resource can have the same configuration of resource elements carrying reference RF signals, which, from the receiver's perspective, have each been encoded by the same antenna port or the same MIMO precoder as the resource elements in the first reference RF signal resource. That is, resource elements carrying reference RF signals within a single reference RF signal resource will be encoded differently, but will be encoded identically across multiple reference RF signal resources.

[0103] These techniques can be implemented in various ways. In one aspect, each positioning reference RF signal resource may have a configured precoder granularity (PRG), which may be equal to a wideband frequency or narrowband frequency value (in which LTE operates). In another aspect, each positioning reference RF signal resource may have a configured time coherence parameter, which indicates whether the receiver can assume that the antenna ports used for the positioning reference RF signal resource are identical across the OFDM symbols / slots within that time coherence parameter.

[0104] For example, if the time coherence parameter is four OFDM symbols, the receiver can assume that the reference RF signal transmitted in a group of four symbols uses the same antenna port / MIMO precoder, but cannot assume that the reference RF signal transmitted in a subsequent group of four symbols uses the same antenna port / MIMO precoder as the first group of four symbols.

[0105] However, the receiver will be able to use the reference RF signals in these two symbol groups to determine the LOS path.

[0106] On another front, the receiver can be configured with multiple positioning reference RF signal resources on the same OFDM symbols but in disjoint subbands, and the receiver can report a TDOA estimate after jointly processing these resources. These resources may belong to the same positioning set, and the receiver can report a TDOA estimate across that set. The receiver can also report which reference RF signal resource in that set was used to derive the reported TDOA measurement among all RS resources in that set. That is, the receiver can determine which reference RF signal resource in the set has a LOS reference RF signal, use that reference RF signal to determine the TDOA, and report that reference RF signal resource to the transmitter. The transmitter can then use that reference RF signal resource / MIMO precoder when transmitting reference RF signals to the receiver in the future.

[0107] On one hand, precoder looping, or SCDD, can be used to transmit positioning reference RF signal resources. In SCDD, one reference RF signal resource is transmitted with a first predetermined delay, subsequent reference RF signal resources are transmitted with another predetermined delay, and so on. In this way, the receiver can determine which one uses the LOS path. For precoder looping, the transmitter uses a different precoder sequence for each of a certain loop of precoding (e.g., four precodes) and then repeats it. The receiver can be configured with reference resources and positioning reference RF signal resources, one of which is transmitted using an antenna port derived using a predefined precoder looping method for the reference resource. The reference resource can be a synchronization signal block (SSB), CSI-RS, TRS, or another positioning reference RF signal resource.

[0108] In all of the above aspects, the receiver may indicate the PRG, or the precoder cyclic sequence, or the time delay to be applied to the SCDDD, or the number of different location reference RF signal resources in the reference RF signal resource set. The receiver's indications(s) may be based on the receiver's capabilities related to the PRG, precoder cyclic sequence, time delay, etc. The receiver's indications(s) are only applicable in scenarios based on receiver-assisted positioning (where the receiver determines its own location) rather than receiver-assisted positioning (where a location server or other network entity determines the receiver's location). In the case of receiver-assisted positioning, the receiver assumes that a wideband precoder is used to locate the reference RF signal.

[0109] Note that although the preceding description has generally stated that the transmitter is a base station and the receiver is a UE, it will be understood that the transmitter can be a UE and the receiver can be a base station, or both the transmitter and the receiver can be a UE or a base station.

[0110] Figure 8An exemplary method 800 for transmitting a reference signal for positioning estimation over a MIMO channel according to at least one aspect of this disclosure is described. Method 800 may be performed by a first node (such as a base station 310 or UE 350 having a transmitter 700).

[0111] At 802, a first node 805 (e.g., TX processor 710 and / or TX MIMO processor 720) is configured to transmit a first set of reference signal resources (one or more reference signal resources) of reference signals(one or more) of a first set. In one aspect, the first set of reference signal resources may appear on a first subband of the MIMO channel and / or during a first time interval on the MIMO channel. In one aspect, as described herein, each reference signal resource in the first set of reference signal resources may utilize at least a first MIMO precoder or multiple MIMO precoders (e.g., different MIMO precoders for each reference signal resource). In another aspect, each reference signal resource in the first set of reference signal resources may utilize a first plurality of MIMO precoders (including the first MIMO precoder) that vary with time and / or frequency.

[0112] At 804, the first node 805 (e.g., TX processor 710 and / or TX MIMO processor 720) is configured to transmit a second set of reference signal resources (one or more reference signal resources) of the second set of reference signals. In one aspect, the second set of reference signal resources may appear on a second subband of the MIMO channel and / or during a second time interval on the MIMO channel. In one aspect, as described herein, each reference signal resource in the second set of reference signal resources may utilize at least a second MIMO precoder or multiple MIMO precoders (e.g., different MIMO precoders for each reference signal resource). In one aspect, each reference signal resource in the second set of reference signal resources may utilize a second plurality of MIMO precoders (including the second MIMO precoder) that vary with time and / or frequency. In one aspect, method 800 may further include receiving at the first node 805 an indication from the second node of the number of reference signal resources to be included in the first and second sets of reference signal resources.

[0113] In one aspect, the first plurality of MIMO precoders and the second plurality of MIMO precoders may vary with time and / or frequency for each reference signal resource in the first and second reference signal resource sets based on a configured precoder granularity. In another aspect, method 800 may further include receiving an indication of the configured precoder granularity from the second node at the first node 805.

[0114] In one aspect, the first plurality of MIMO precoders and the second plurality of MIMO precoders may vary with time and / or frequency for each reference signal resource in the first and second reference signal resource sets based on configured time coherence parameters. In another aspect, method 800 may further include receiving an indication of the configured time coherence parameters from the second node at the first node 805.

[0115] In one aspect, the first plurality of MIMO precoders and the second plurality of MIMO precoders may vary with time and / or frequency for each reference signal resource in the first and second reference signal resource sets based on the configured SCDDD. In another aspect, method 800 may further include receiving an indication of the configured SCDDD from the second node at the first node 805.

[0116] In one aspect, the first plurality of MIMO precoders and the second plurality of MIMO precoders may vary over time and / or frequency for each reference signal resource in the first and second reference signal resource sets based on a configured precoder cycle set and precoder cycle order. In another aspect, method 800 may further include receiving, at a first node 805, an indication of the configured precoder cycle set and precoder cycle order from a second node.

[0117] At 806, the first node 805 (e.g., antennas 732, transmitters 730, TX MIMO processor 720 and / or TX processor 710) transmits the first reference signal set to the second node (e.g., another of base station 310 or UE 350) using a first reference signal resource set on the first subband of the MIMO channel and / or during a first time interval on the MIMO channel.

[0118] At 808, the first node 805 (e.g., antennas 732, transmitters 730, TX MIMO processor 720 and / or TX processor 710) transmits a second reference signal set to the second node using a second reference signal resource set on the second subband of the MIMO channel and / or during a second time interval on the MIMO channel.

[0119] In one aspect, the first reference signal resource set may include multiple reference signal resources on the same OFDM symbols in disjoint subbands of the MIMO channel. In another aspect, method 800 may further include: receiving a TDOA estimate from a second node at a first node 805 based at least in part on a first reference signal set and a second reference signal set transmitted on the first and second reference signal resource sets; or receiving, at the first node 805, a position estimate of the second node calculated based at least in part on the first and second reference signal sets transmitted on the first and second reference signal resource sets. In another aspect, method 800 may further include receiving, at the first node 805, identifiers of reference signal resources in the first and second reference signal resource sets used to derive the TDOA estimate or the position estimate of the second node. In another aspect, the first node 805 uses the identified reference signal resources to transmit subsequent reference signals to the second node.

[0120] On one hand, the first MIMO precoder and the second MIMO precoder used in each subband of the first subband and the second subband can be pseudo-randomly selected MIMO precoders based on a cyclic set of MIMO precoders.

[0121] In one aspect, method 800 may further include receiving, at the first node 805, recommendations from the second node for a first MIMO precoder and a second MIMO precoder to be used for encoding the first reference signal resource set and the second reference signal resource set.

[0122] Figure 9 An exemplary method 900 for processing reference signals for positioning estimation on a MIMO channel is described. Method 900 can be performed by a second node (such as base station 310 or UE 350).

[0123] At 902, a second node 905 (e.g., antennas 320, receivers 318b, and / or RX processor 370, or antennas 352, receivers 354a, and / or RX processor 356) receives from a first node (e.g., another of base station 310 or UE 350) a first set of reference signals (one or more of the reference signal resources) on a first set of reference signal resources. In one aspect, the first set of reference signal resources may appear on a first subband of the MIMO channel and / or during a first time interval on the MIMO channel. In one aspect, as described herein, each reference signal resource in the first set of reference signal resources may utilize at least a first MIMO precoder or multiple MIMO precoders (e.g., different MIMO precoders for each reference signal resource). In another aspect, each reference signal resource in the first set of reference signal resources may utilize a first plurality of MIMO precoders (including the first MIMO precoder) that vary with time and / or frequency.

[0124] At 904, a second node 905 (e.g., antennas 320, receivers 318b, and / or RX processor 370, or antennas 352, receivers 354a, and / or RX processor 356) receives from the first node one or more reference signals from a second set of reference signal resources on a second set of reference signal resources. In one aspect, the second set of reference signal resources may appear on a second subband of the MIMO channel and / or during a second time interval on the MIMO channel. In one aspect, as described herein, each reference signal resource in the second set of reference signal resources may utilize at least a second MIMO precoder or multiple MIMO precoders (e.g., different MIMO precoders for each reference signal resource). In one aspect, each reference signal resource in the second set of reference signal resources may utilize a second plurality of MIMO precoders (including the second MIMO precoder) that vary with time and / or frequency.

[0125] At 906, the second node 905 (e.g., RX processor 370 and / or controller / processor 375, or RX processor 356 and / or controller / processor 359) identifies at least one reference signal transmitted on the first reference signal resource set and the second reference signal resource set as following the LOS path between the second node and the first node.

[0126] At 908, the second node 905 (e.g., RX processor 370 and / or controller / processor 375, or RX processor 356 and / or controller / processor 359) performs TDOA measurement based on the at least one reference signal.

[0127] In one aspect, method 900 may further include sending an indication of a configured precoder granularity from a second node 905 to a first node, wherein the first plurality of MIMO precoders and the second plurality of MIMO precoders may vary with time and / or frequency for each reference signal resource in the first and second reference signal resource sets based on the configured precoder granularity.

[0128] In one aspect, method 900 may further include sending an indication of configured time coherence parameters from a second node 905 to a first node, wherein the first plurality of MIMO precoders and the second plurality of MIMO precoders may vary with time and / or frequency for each reference signal resource in the first and second reference signal resource sets based on the configured time coherence parameters.

[0129] In one aspect, method 900 may further include sending an indication of a configured SCDDD from a second node 905 to a first node, wherein the first plurality of MIMO precoders and the second plurality of MIMO precoders may vary with time and / or frequency for each reference signal resource in the first and second reference signal resource sets based on the configured SCDDD.

[0130] In one aspect, method 900 may further include sending an instruction from a second node 905 to a first node for a configured precoder cycle set and a precoder cycle order, wherein the first plurality of MIMO precoders and the second plurality of MIMO precoders may vary over time and / or frequency for each reference signal resource in the first reference signal resource set and the precoder cycle order based on the configured precoder cycle set and the precoder cycle order.

[0131] In one aspect, method 900 may further include sending a recommendation from the second node 905 to the first node regarding the number of reference signal resources to be included in the first reference signal resource set.

[0132] In one aspect, method 900 may further include: the second node 905 sending to the first node an identifier of a reference signal resource carrying the at least one reference signal used to derive a TDOA measurement or a position estimate of the second node, the TDOA measurement or position estimate of the second node being calculated at least in part based on a first reference signal set and a second reference signal set transmitted on a first reference signal resource set and a second reference signal resource set.

[0133] In one aspect, method 900 may further include sending recommendations from second node 905 to first node for a first MIMO precoder and a second MIMO precoder to be used for encoding the first reference signal resource set and the second reference signal resource set.

[0134] Those skilled in the art will appreciate that information and signals can be represented using any of a variety of different techniques and skills. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referred to throughout the above description can be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, light fields or light particles, or any combination thereof.

[0135] Furthermore, those skilled in the art will appreciate that the various illustrative logic blocks, modules, circuits, and algorithmic steps described in conjunction with the aspects disclosed herein can be implemented as electronic hardware, computer software, or a combination of both. To clearly illustrate this interchangeability between hardware and software, the various illustrative components, blocks, modules, circuits, and steps are described above in a generalized manner in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall 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 construed as departing from the scope of the aspects described herein.

[0136] The various illustrative logic blocks, modules, and circuits described in conjunction with the aspects disclosed herein may be implemented or executed using a general-purpose processor, digital signal processor (DSP), application-specific integrated circuit (ASIC), 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. The general-purpose processor may be a microprocessor, but in alternative embodiments, it 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, multiple microprocessors, one or more microprocessors cooperating with a DSP core, or other such configurations).

[0137] The methods, sequences, and / or algorithms described in conjunction with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of both. The software module may reside in random access memory (RAM), flash memory, read-only memory (ROM), erasable programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), registers, hard disks, removable disks, CD-ROMs, or any other form of non-transient computer-readable medium known in the art. An exemplary non-transient computer-readable medium may be coupled to a processor so that the processor can read / write information from / to the non-transient computer-readable medium. Alternatively, the non-transient computer-readable medium may be integrated into the processor. The processor and non-transient computer-readable medium may reside in an ASIC. The ASIC may reside in a user equipment (e.g., UE) or a base station. Alternatively, the processor and non-transient computer-readable medium may be discrete components in a user equipment or base station.

[0138] In one or more exemplary aspects, the functions described herein may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or codes on or transmitted via a non-transient computer-readable medium. Computer-readable media may include storage media and / or communication media, including any non-transient medium that facilitates the transfer of a computer program from one location to another. Storage media may be any available medium accessible to a computer. By way of example and not limitation, such computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disc storage, disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and is accessible to a computer. Any connection is also legitimately referred to as a computer-readable medium. For example, if the software is transmitted 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 microwave, then coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. The terms disk and disc, which may be used interchangeably in this document, include compact discs (CDs), laser discs, optical discs, digital video discs (DVDs), floppy disks, and... Discs, which often reproduce data magnetically and / or optically using lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0139] Although the foregoing disclosure has shown illustrative aspects, those skilled in the art will appreciate that various changes and modifications may be made therein without departing from the scope of this disclosure as defined in the appended claims. Furthermore, based on the various illustrative aspects described herein, those skilled in the art will appreciate that the functions, steps, and / or actions recited in any of the foregoing methods and / or in any of the appended method claims need not be performed in any particular order. Moreover, with respect to any element described for the foregoing or recited in the appended claims in a singular form, those skilled in the art will appreciate that the singular form also contemplates a plural form, unless explicitly stated to be limited to the singular form.

Claims

1. A network node configured to transmit reference signals for positioning estimation over a multipath multiple-input multiple-output (MIMO) channel, comprising: a memory; at least one transceiver; and at least one processor coupled to the memory and the at least one transceiver, the at least one processor configured to: configure a first set of reference signal resources for transmitting a first set of reference signals, wherein the first set of reference signal resources is scheduled with a first periodicity over a first set of physical resource blocks of the MIMO channel, and wherein each reference signal resource of the first set of reference signal resources utilizes at least a first MIMO precoder; and configure a second set of reference signal resources for transmitting a second set of reference signals, wherein the second set of reference signal resources is scheduled with a second periodicity over a second set of physical resource blocks of the MIMO channel, and wherein each reference signal resource of the second set of reference signal resources utilizes at least a second MIMO precoder; transmit, via the at least one transceiver, the first set of reference signals over the MIMO channel using the first set of reference signal resources over the first set of physical resource blocks of the MIMO channel with the first periodicity; and transmit, via the at least one transceiver, the second set of reference signals over the MIMO channel using the second set of reference signal resources over the second set of physical resource blocks of the MIMO channel with the second periodicity, wherein the first set of reference signals and the second set of reference signals are transmitted to assist a user equipment (UE) in performing positioning measurements based on processing of the first set of reference signals and the second set of reference signals.

2. The network node of claim 1, wherein: each reference signal resource of the first set of reference signal resources utilizes a first plurality of MIMO precoders including the first MIMO precoder that varies over time and / or frequency, and each reference signal resource of the second set of reference signal resources utilizes a second plurality of MIMO precoders including the second MIMO precoder that varies over time and / or frequency.

3. The network node of claim 2, wherein the first plurality of MIMO precoders and the second plurality of MIMO precoders vary over time and / or frequency for each reference signal resource of the first set of reference signal resources and the second set of reference signal resources based on a configured precoder granularity.

4. The network node of claim 3, wherein the at least one processor is further configured to: receive, via the at least one transceiver, an indication of the configured precoder granularity.

5. The network node of claim 2, wherein the first plurality of MIMO precoders and the second plurality of MIMO precoders vary over time and / or frequency for each reference signal resource of the first set of reference signal resources and the second set of reference signal resources based on a configured time coherence parameter.

6. The network node of claim 5, wherein the at least one processor is further configured to: receive, via the at least one transceiver, an indication of a configured time coherence parameter.

7. The network node of claim 2, wherein the first plurality of MIMO precoders and the second plurality of MIMO precoders vary with time and / or frequency for each reference signal resource in the first set of reference signal resources and the second set of reference signal resources based on a configured small delay cyclic delay diversity (SDCDD).

8. The network node of claim 7, wherein the at least one processor is further configured to: receive, via the at least one transceiver, an indication of the configured SDCDD.

9. The network node of claim 2, wherein the first plurality of MIMO precoders and the second plurality of MIMO precoders vary with time and / or frequency for each reference signal resource in the first set of reference signal resources and the second set of reference signal resources based on a configured precoder cycling set and a precoder cycling order.

10. The network node of claim 9, wherein the at least one processor is further configured to: receive, via the at least one transceiver, an indication of the configured precoder cycling set and the precoder cycling order.

11. The network node of claim 1, wherein the at least one processor is further configured to: receive, via the at least one transceiver, an indication of a number of reference signal resources to include in the first set of reference signal resources and the second set of reference signal resources.

12. The network node of claim 1, wherein the first set of reference signal resources includes a plurality of reference signal resources on a same orthogonal frequency-division multiplexing (OFDM) symbol in disjoint subbands of the MIMO channel.

13. The network node of claim 1, wherein the first MIMO precoder and the second MIMO precoder used in each physical resource block of the first set of physical resource blocks and the second set of physical resource blocks are pseudo-randomly selected MIMO precoders based on a set of MIMO precoder cycles.

14. The network node of claim 1, wherein the at least one processor is further configured to: receive, via the at least one transceiver, a recommendation of the first MIMO precoder and the second MIMO precoder to use for encoding the first set of reference signal resources and the second set of reference signal resources.

15. A user equipment (UE) configured to process reference signals for positioning estimation over a multipath multiple-input multiple-output (MIMO) channel, comprising: a memory; at least one transceiver; and at least one processor coupled to the memory and the at least one transceiver, the at least one processor configured to: receive, via the at least one transceiver, an indication of a configured time coherence parameter. receive, from a network node, a first set of reference signals over a first set of reference signal resources via the at least one transceiver, wherein the first set of reference signal resources is scheduled with a first periodicity over a first set of physical resource blocks of the MIMO channel, and wherein each reference signal resource of the first set of reference signal resources utilizes at least a first MIMO precoder; receive, from the network node, a second set of reference signals over a second set of reference signal resources via the at least one transceiver, wherein the second set of reference signal resources is scheduled with a second periodicity over a second set of physical resource blocks of the MIMO channel, and wherein each reference signal resource of the second set of reference signal resources utilizes at least a second MIMO precoder; identify at least one reference signal communicated over the first set of reference signal resources and the second set of reference signal resources as following a line-of-sight (LOS) path between the UE and the network node; and perform a time-difference-of-arrival (TDOA) measurement based on the at least one reference signal.

16. The UE of claim 15, wherein: each reference signal resource of the first set of reference signal resources utilizes a first plurality of MIMO precoders including the first MIMO precoder that varies over time and / or frequency, and each reference signal resource of the second set of reference signal resources utilizes a second plurality of MIMO precoders including the second MIMO precoder that varies over time and / or frequency.

17. The UE of claim 16, wherein: the at least one processor is further configured to send, to the network node via the at least one transceiver, an indication of a configured precoder granularity, and the first plurality of MIMO precoders and the second plurality of MIMO precoders vary over time and / or frequency for each reference signal resource of the first set of reference signal resources and the second set of reference signal resources based on the configured precoder granularity.

18. The UE of claim 16, wherein: the at least one processor is further configured to send, to the network node via the at least one transceiver, an indication of a configured time coherence parameter, and the first plurality of MIMO precoders and the second plurality of MIMO precoders vary over time and / or frequency for each reference signal resource of the first set of reference signal resources and the second set of reference signal resources based on the configured time coherence parameter.

19. The UE of claim 16, wherein: the at least one processor is further configured to send, to the network node via the at least one transceiver, an indication of a configured small delay cyclic delay diversity (SDCDD), and the first plurality of MIMO precoders and the second plurality of MIMO precoders vary over time and / or frequency for each reference signal resource of the first set of reference signal resources and the second set of reference signal resources based on the configured SDCDD.

20. The UE of claim 16, wherein: ​ the at least one processor is further configured to transmit, to the network node via the at least one transceiver, an indication of the configured set of precoder cycles and the precoder cycle ordering, and the first and second pluralities of MIMO precoders vary with time and / or frequency for each reference signal resource in the first and second sets of reference signal resources based on the configured set of precoder cycles and the precoder cycle ordering.

21. The UE of claim 15, wherein the at least one processor is further configured to: transmit, to the network node via the at least one transceiver, a recommendation of a number of reference signal resources to include in the first set of reference signal resources.

22. The UE of claim 15, wherein the at least one processor is further configured to: transmit, to the network node via the at least one transceiver, a recommendation of the first and second MIMO precoders to use for encoding the first and second sets of reference signal resources.

23. A method for transmitting reference signals for positioning estimation over a multipath multiple-input multiple-output (MIMO) channel performed by a network node, comprising: configuring a first set of reference signal resources for transmitting a first set of reference signals, wherein the first set of reference signal resources is scheduled with a first periodicity over a first set of physical resource blocks of the MIMO channel, and wherein each reference signal resource in the first set of reference signal resources utilizes at least a first MIMO precoder; configuring a second set of reference signal resources for transmitting a second set of reference signals, wherein the second set of reference signal resources is scheduled with a second periodicity over a second set of physical resource blocks of the MIMO channel, and wherein each reference signal resource in the second set of reference signal resources utilizes at least a second MIMO precoder; transmitting, over the MIMO channel, the first set of reference signals using the first set of reference signal resources with the first periodicity over the first set of physical resource blocks of the MIMO channel; and transmitting, over the MIMO channel, the second set of reference signals using the second set of reference signal resources with the second periodicity over the second set of physical resource blocks of the MIMO channel, wherein the first and second sets of reference signals are transmitted to assist a user equipment (UE) in performing positioning measurements based on processing of the first and second sets of reference signals.

24. The method of claim 23, wherein: each reference signal resource in the first set of reference signal resources utilizes a first plurality of MIMO precoders including the first MIMO precoder that varies with time and / or frequency, and each reference signal resource in the second set of reference signal resources utilizes a second plurality of MIMO precoders including the second MIMO precoder that varies with time and / or frequency. ​ 25. The method of claim 23, wherein the first set of reference signal resources comprises multiple reference signal resources on the same orthogonal frequency-division multiplexing (OFDM) symbol in disjoint subbands of the MIMO channel.

26. The method of claim 23, wherein the first MIMO precoder and the second MIMO precoder used in each of a first subband and a second subband are pseudo-randomly chosen MIMO precoders based on a set of MIMO precoder cycles.

27. A method for processing reference signals for positioning estimation over a multipath multiple-input multiple-output (MIMO) channel performed by a user equipment (UE), comprising: receiving a first set of reference signals from a network node on a first set of reference signal resources, wherein the first set of reference signal resources is scheduled on a first set of physical resource blocks of the MIMO channel with a first periodicity, and wherein each reference signal resource in the first set of reference signal resources utilizes at least a first MIMO precoder; receiving a second set of reference signals from the network node on a second set of reference signal resources, wherein the second set of reference signal resources is scheduled on a second set of physical resource blocks of the MIMO channel with a second periodicity, and wherein each reference signal resource in the second set of reference signal resources utilizes at least a second MIMO precoder; identifying at least one reference signal communicated on the first set of reference signal resources and the second set of reference signal resources as following a line-of-sight (LOS) path between the UE and the network node; and performing a time-difference-of-arrival (TDOA) measurement based on the at least one reference signal.

28. The method of claim 27, wherein: each reference signal resource in the first set of reference signal resources utilizes a first plurality of MIMO precoders including the first MIMO precoder that varies over time and / or frequency, and each reference signal resource in the second set of reference signal resources utilizes a second plurality of MIMO precoders including the second MIMO precoder that varies over time and / or frequency.

29. The method of claim 27, further comprising: sending a recommendation to the network node of a number of reference signal resources to include in the first set of reference signal resources.

30. The method of claim 27, further comprising: sending a recommendation to the network node of the first MIMO precoder and the second MIMO precoder to use for encoding the first set of reference signal resources and the second set of reference signal resources. ​

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