Techniques for high positioning accuracy with limited-bandwidth

Abstract

Various aspects of the present disclosure relate to techniques for carrier phase measurement reporting within a measurement time window. A network equipment (NE) may be configured to transmit a reference signal (RS) to a plurality of distributed units (DUs) for synchronization between each of the plurality of DUs, mitigate a synchronization offset between each of the plurality of DUs, and transmit an radio frequency (RF)-coherent positioning reference signal (PRS), based on the synchronization, to a target device for estimating a location of the target device, the coherent PRS allowing a higher signal-to-noise ratio (SNR) for estimating the location.

Description

TECHNIQUES FOR HIGH POSITIONING ACCURACY WITH LIMITED- BANDWIDTH TECHNICAL FIELD

[0001] The present disclosure relates to wireless communications, and more specifically to techniques for high positioning accuracy in limited-bandwidth scenarios. BACKGROUND

[0002] A wireless communications system may include one or multiple network communication devices, which may be otherwise knowns as network equipment (NE), supporting wireless communications for one or multiple user communication devices, which may be otherwise known as user equipment (UE), or other suitable terminology. The wireless communications system may support wireless communications with one or multiple user communication devices by utilizing resources of the wireless communication system (e.g., time resources (e.g., symbols, slots, subframes, frames, or the like) or frequency resources (e.g., subcarriers, carriers, or the like). Additionally, the wireless communications system may support wireless communications across various radio access technologies including third generation (3G) radio access technology, fourth generation (4G) radio access technology, fifth generation (5G) radio access technology, among other suitable radio access technologies beyond 5G (e.g., sixth generation (6G)). SUMMARY

[0003] An article “a” before an element is unrestricted and understood to refer to “at least one” of those elements or “one or more” of those elements. The terms “a,” “at least one,” “one or more,” and “at least one of one or more” may be interchangeable. As used herein, including in the claims, “or” as used in a list of items (e.g., a list of items prefaced by a phrase such as “at least one of” or “one or more of” or “one or both of”) indicates an inclusive list such that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Also, as used herein, the phrase “based on” shall not be construed as a reference to a closed set of conditions. For example, an example step that is described as “based on condition A” may be based on both a condition A and a condition B without departing from the scopeof the present disclosure. In other words, as used herein, the phrase “based on” shall be construed in the same manner as the phrase “based at least in part on. Further, as used herein, including in the claims, a “set” may include one or more elements.

[0004] Some implementations of the method and apparatuses described herein may further transmit a reference signal (RS) to a plurality of distributed units (DUs) for synchronization between each of the plurality of DUs, mitigate a synchronization offset between each of the plurality of DUs, and transmit a radio frequency (RF)-coherent positioning RS (PRS), based on the synchronization, to a target device for estimating a location of the target device, the coherent PRS allowing a higher signal-to-noise ratio (SNR) for estimating the location.

[0005] Some implementations of the method and apparatuses described herein may further receive an RF-coherent PRS from each of a plurality of DUs for estimating a location of the UE, the coherent PRS allowing a higher SNR for estimating the location, perform measurements over the received RF-coherent PRSs according to a configured positioning technique, estimate the location of the UE based on the RF-coherent PRS received from each of the plurality of DUs in a UE-based positioning scenario, and transmit the estimated location measurements to an NE in a network-based positioning scenario. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1A illustrates an example of a wireless communications system in accordance with aspects of the present disclosure.

[0007] Figure 1B depicts an overview of one embodiment of the absolute and relative positioning scenarios, in accordance with aspects of the present disclosure.

[0008] Figure 2 illustrates an example of an architecture for new radio (NR) downlink (DL)-based positioning measurements and RSs, in accordance with aspects of the present disclosure.

[0009] Figure 3 depicts a graph that shows the Cramer-Rao Lower Bound (CRLB) for different PRS bandwidths and different SNR ranges in accordance with aspects of the present disclosure.

[0010] Figure 4 depicts an example of an RF-coherent PRS transmission, in accordance with aspects of the present disclosure.

[0011] Figure 5 illustrates an example of a UE in accordance with aspects of the present disclosure.

[0012] Figure 6 illustrates an example of a processor in accordance with aspects of the present disclosure.

[0013] Figure 7 illustrates an example of a NE in accordance with aspects of the present disclosure.

[0014] Figure 8 illustrate a flowcharts of method performed by a UE in accordance with aspects of the present disclosure.

[0015] Figure 9 illustrate a flowcharts of method performed by a NE in accordance with aspects of the present disclosure. DETAILED DESCRIPTION

[0016] For positioning, a target-UE usually performs measurement and processing of Uu PRS prior to reporting the measurements to a location server. In a similar manner, performing measurement and processing of a SL PRS remains an issue as different SL UEs may support different processing capabilities ranging from basic to advanced devices. During SL positioning study phase, companies have performed SL positioning evaluation over different SL PRS bandwidths and have shown that the larger SL PRS bandwidth the better the positioning accuracy and this applies to several RAT- dependent positioning techniques such as timing-based and angular-based. However, PRS bandwidths are generally limited, for example, in a vehicle-to-everything (V2X) case, intelligent transport system (ITS) band is limited to 70MHz and V2X positioning target requirements have been shown to be achievable when a bandwidth of at least 100Mhz is used for PRS transmission.

[0017] Distributed Antenna Systems (DAS) increase communication capabilities such as antenna coverage. The aim of the antenna distribution technique is to leverage DAS and improve the positioning performance such as accuracy, reliability, and availability. Instead of using different TRPs to locate a UE, different distributed antennas (e.g., DUs) controlled by the same central unit (CU) could be used for UE positioning. Additionally, distributed antennas allow for more diversity of line of sight (LOS) links with a target UE, e.g., without depending on a single link to perform positioning.

[0018] This disclosure presents solutions that allow leveraging DASs and coherent RF transmission techniques to further enhance positioning accuracy in bandwidth- limited scenarios. In this disclosure, distributed antennas coordinate to synchronize their frequency, phase, and timing of their downlink (DL) / sidelink (SL) PRSs and consequently transmit RF-coherent DL PRSs to a target UE.

[0019] Aspects of the present disclosure are described in the context of a wireless communications system.

[0020] Figure 1A illustrates an example of a wireless communications system 100 in accordance with aspects of the present disclosure. The wireless communications system 100 may include one or more NE 102, one or more UE 104, and a core network (CN) 106. The wireless communications system 100 may support various radio access technologies. In some implementations, the wireless communications system 100 may be a 4G network, such as an LTE network or an LTE-Advanced (LTE-A) network. In some other implementations, the wireless communications system 100 may be a NR network, such as a 5G network, a 5G-Advanced (5G-A) network, or a 5G ultrawideband (5G-UWB) network. In other implementations, the wireless communications system 100 may be a combination of a 4G network and a 5G network, or other suitable radio access technology including Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20. The wireless communications system 100 may support radio access technologies beyond 5G, for example, 6G. Additionally, the wireless communications system 100 may support technologies, such as time division multiple access (TDMA), frequency division multiple access (FDMA), or code division multiple access (CDMA), etc.

[0021] The one or more NE 102 may be dispersed throughout a geographic region to form the wireless communications system 100. One or more of the NE 102 described herein may be or include or may be referred to as a network node, a base station, a network element, a network function, a network entity, a radio access network (RAN), a NodeB, an eNodeB (eNB), a next-generation NodeB (gNB), or other suitable terminology. An NE 102 and a UE 104 may communicate via a communication link, which may be a wireless or wired connection. For example, an NE 102 and a UE 104 may perform wireless communication (e.g., receive signaling, transmit signaling) over a Uu interface.

[0022] An NE 102 may provide a geographic coverage area for which the NE 102 may support services for one or more UEs 104 within the geographic coverage area. For example, an NE 102 and a UE 104 may support wireless communication of signals related to services (e.g., voice, video, packet data, messaging, broadcast, etc.) according to one or multiple radio access technologies. In some implementations, an NE 102 may be moveable, for example, a satellite associated with a non-terrestrial network (NTN). In some implementations, different geographic coverage areas 112 associated with the same or different radio access technologies may overlap, but the different geographic coverage areas may be associated with different NE 102.

[0023] The one or more UE 104 may be dispersed throughout a geographic region of the wireless communications system 100. A UE 104 may include or may be referred to as a remote unit, a mobile device, a wireless device, a remote device, a subscriber device, a transmitter device, a receiver device, or some other suitable terminology. In some implementations, the UE 104 may be referred to as a unit, a station, a terminal, or a client, among other examples. Additionally, or alternatively, the UE 104 may be referred to as an Internet-of-Things (IoT) device, an Internet-of-Everything (IoE) device, or machine-type communication (MTC) device, among other examples.

[0024] A UE 104 may be able to support wireless communication directly with other UEs 104 over a communication link. For example, a UE 104 may support wireless communication directly with another UE 104 over a device-to-device (D2D) communication link. In some implementations, such as vehicle-to-vehicle (V2V) deployments, vehicle-to-everything (V2X) deployments, or cellular-V2X deployments, the communication link 114 may be referred to as a sidelink. For example, a UE 104 may support wireless communication directly with another UE 104 over a PC5 interface.

[0025] An NE 102 may support communications with the CN 106, or with another NE 102, or both. For example, an NE 102 may interface with other NE 102 or the CN 106 through one or more backhaul links (e.g., S1, N2, N2, or network interface). In some implementations, the NE 102 may communicate with each other directly. In some other implementations, the NE 102 may communicate with each other or indirectly (e.g., via the CN 106. In some implementations, one or more NE 102 may include subcomponents, such as an access network entity, which may be an example of anaccess node controller (ANC). An ANC may communicate with the one or more UEs 104 through one or more other access network transmission entities, which may be referred to as a radio heads, smart radio heads, or TRPs.

[0026] The CN 106 may support user authentication, access authorization, tracking, connectivity, and other access, routing, or mobility functions. The CN 106 may be an evolved packet core (EPC), or a 5G core (5GC), which may include a control plane entity that manages access and mobility (e.g., a mobility management entity (MME), an access and mobility management functions (AMF)) and a user plane entity that routes packets or interconnects to external networks (e.g., a serving gateway (S-GW), a Packet Data Network (PDN) gateway (P-GW), or a user plane function (UPF)). In some implementations, the control plane entity may manage non-access stratum (NAS) functions, such as mobility, authentication, and bearer management (e.g., data bearers, signal bearers, etc.) for the one or more UEs 104 served by the one or more NE 102 associated with the CN 106.

[0027] The CN 106 may communicate with a packet data network over one or more backhaul links (e.g., via an S1, N2, N2, or another network interface). The packet data network may include an application server. In some implementations, one or more UEs 104 may communicate with the application server. A UE 104 may establish a session (e.g., a protocol data unit (PDU) session, or the like) with the CN 106 via an NE 102. The CN 106 may route traffic (e.g., control information, data, and the like) between the UE 104 and the application server using the established session (e.g., the established PDU session). The PDU session may be an example of a logical connection between the UE 104 and the CN 106 (e.g., one or more network functions of the CN 106).

[0028] In the wireless communications system 100, the NEs 102 and the UEs 104 may use resources of the wireless communications system 100 (e.g., time resources (e.g., symbols, slots, subframes, frames, or the like) or frequency resources (e.g., subcarriers, carriers)) to perform various operations (e.g., wireless communications). In some implementations, the NEs 102 and the UEs 104 may support different resource structures. For example, the NEs 102 and the UEs 104 may support different frame structures. In some implementations, such as in 4G, the NEs 102 and the UEs 104 may support a single frame structure. In some other implementations, such as in 5G and among other suitable radio access technologies, the NEs 102 and the UEs 104 maysupport various frame structures (i.e., multiple frame structures). The NEs 102 and the UEs 104 may support various frame structures based on one or more numerologies.

[0029] One or more numerologies may be supported in the wireless communications system 100, and a numerology may include a subcarrier spacing and a cyclic prefix. A first numerology (e.g., ^=0) may be associated with a first subcarrier spacing (e.g., 15 kHz) and a normal cyclic prefix. In some implementations, the first numerology (e.g., ^=0) associated with the first subcarrier spacing (e.g., 15 kHz) may utilize one slot per subframe. A second numerology (e.g., ^=1) may be associated with a second subcarrier spacing (e.g., 30 kHz) and a normal cyclic prefix. A third numerology (e.g., ^=2) may be associated with a third subcarrier spacing (e.g., 60 kHz) and a normal cyclic prefix or an extended cyclic prefix. A fourth numerology (e.g., ^=3) may be associated with a fourth subcarrier spacing (e.g., 120 kHz) and a normal cyclic prefix. A fifth numerology (e.g., ^=4) may be associated with a fifth subcarrier spacing (e.g., 240 kHz) and a normal cyclic prefix.

[0030] A time interval of a resource (e.g., a communication resource) may be organized according to frames (also referred to as radio frames). Each frame may have a duration, for example, a 10 millisecond (ms) duration. In some implementations, each frame may include multiple subframes. For example, each frame may include 10 subframes, and each subframe may have a duration, for example, a 1 ms duration. In some implementations, each frame may have the same duration. In some implementations, each subframe of a frame may have the same duration.

[0031] Additionally or alternatively, a time interval of a resource (e.g., a communication resource) may be organized according to slots. For example, a subframe may include a number (e.g., quantity) of slots. The number of slots in each subframe may also depend on the one or more numerologies supported in the wireless communications system 100. For instance, the first, second, third, fourth, and fifth numerologies (i.e., ^=0, ^=1, ^=2, ^=3, ^=4) associated with respective subcarrier spacings of 15 kHz, 30 kHz, 60 kHz, 120 kHz, and 240 kHz may utilize a single slot per subframe, two slots per subframe, four slots per subframe, eight slots per subframe, and 16 slots per subframe, respectively. Each slot may include a number (e.g., quantity) of symbols (e.g., OFDM symbols). In some implementations, the number (e.g., quantity) of slots for a subframe may depend on a numerology. For a normal cyclic prefix, a slotmay include 14 symbols. For an extended cyclic prefix (e.g., applicable for 60 kHz subcarrier spacing), a slot may include 12 symbols. The relationship between the number of symbols per slot, the number of slots per subframe, and the number of slots per frame for a normal cyclic prefix and an extended cyclic prefix may depend on a numerology. It should be understood that reference to a first numerology (e.g., ^=0) associated with a first subcarrier spacing (e.g., 15 kHz) may be used interchangeably between subframes and slots.

[0032] In the wireless communications system 100, an electromagnetic (EM) spectrum may be split, based on frequency or wavelength, into various classes, frequency bands, frequency channels, etc. By way of example, the wireless communications system 100 may support one or multiple operating frequency bands, such as frequency range designations FR1 (410 MHz – 7.125 GHz), FR2 (24.25 GHz – 52.6 GHz), FR3 (7.125 GHz – 24.25 GHz), FR4 (52.6 GHz – 114.25 GHz), FR4a or FR4-1 (52.6 GHz – 71 GHz), and FR5 (114.25 GHz – 300 GHz). In some implementations, the NEs 102 and the UEs 104 may perform wireless communications over one or more of the operating frequency bands. In some implementations, FR1 may be used by the NEs 102 and the UEs 104, among other equipment or devices for cellular communications traffic (e.g., control information, data). In some implementations, FR2 may be used by the NEs 102 and the UEs 104, among other equipment or devices for short-range, high data rate capabilities.

[0033] FR1 may be associated with one or multiple numerologies (e.g., at least three numerologies). For example, FR1 may be associated with a first numerology (e.g., ^=0), which includes 15 kHz subcarrier spacing; a second numerology (e.g., ^=1), which includes 30 kHz subcarrier spacing; and a third numerology (e.g., ^=2), which includes 60 kHz subcarrier spacing. FR2 may be associated with one or multiple numerologies (e.g., at least 2 numerologies). For example, FR2 may be associated with a third numerology (e.g., ^=2), which includes 60 kHz subcarrier spacing; and a fourth numerology (e.g., ^=3), which includes 120 kHz subcarrier spacing.

[0034] NR positioning based on NR Uu signals and standalone (SA) architecture (e.g., beam-based transmissions) is discussed in Rel-16. The targeted use cases include commercial and regulatory (emergency services) scenarios, as in Rel-15. Theperformance requirements are shown in the table below, e.g., from TR 38.855 (incorporated herein by reference). Positioning Error Indoor Outdoor Horizontal Positioning < 3m for 80% of UEs < 10m for 80% of UEs Vertical Positioning < 3m for 80% of UEs < 3m for 80% of UEs

[0035] 3GPP Rel-17 Positioning defines the positioning performance requirements for Commercial and industrial Internet of Things (IIoT) use cases, shown in the table below, e.g., as in 3GGPP TR 38.857 (incorporated herein by reference). Positioning Error Commercial IIoT Horizontal Positioning (< 1 m) for 90% of UEs (< 0.2 m) for 90% of UEs; Vertical Positioning (< 3 m) for 90% of UEs (< 1 m) for 90% of UEs Physical layer latency (< 10 ms) (< 10 ms) for position estimation of UE End-to-End Latency (<100 ms) (< 100 ms, in the order of 10 for position estimation ms is desired) of UE

[0036] Figure 1B depicts an overview of one embodiment of the absolute and relative positioning scenarios, in accordance with aspects of the present disclosure. As defined in the architectural (stage 1) specifications, Figure 1B depicts three different co- ordinate systems: Absolute Positioning, fixed coordinate systems 110; Relative Positioning, variable and moving coordinate system 112; and Relative Positioning, variable coordinate system 114.

[0037] RAT-dependent positioning techniques involve the 3GPP RAT and core network entities to perform the position estimation of the UE, which are differentiated from RAT-independent positioning techniques which rely on GNSS, IMU sensor, WLAN and Bluetooth technologies for performing target device (UE) positioning.

[0038] There are various RAT-dependent positioning techniques supported in Rel- 16 and Rel-17. The DL-time difference of arrival (TDOA) positioning method makesuse of the DL RSTD (and optionally DL PRS reference signal received power (RSRP)) of DL signals received from multiple TPs, at the UE. The UE measures the DL reference signal timing difference (RSTD) (and optionally DL PRS RSRP) of the received signals using assistance data received from the positioning server, and the resulting measurements are used along with other configuration information to locate the UE in relation to the neighboring TPs.

[0039] The DL-angle of departure (AoD) positioning method makes use of the measured DL PRS RSRP of DL signals received from multiple TPs, at the UE. The UE measures the DL PRS RSRP of the received signals using assistance data received from the positioning server, and the resulting measurements are used along with other configuration information to locate the UE in relation to the neighboring TPs.

[0040] The multi-round-trip time (RTT) positioning method makes use of the UE Rx-Tx measurements and DL PRS RSRP of DL signals received from multiple TRPs, measured by the UE and the measured gNB Rx-Tx measurements and UL SRS-RSRP at multiple TRPs of uplink signals transmitted from UE. The UE measures the UE Rx-Tx measurements (and optionally DL PRS RSRP of the received signals) using assistance data received from the positioning server, and the TRPs measure the gNB Rx-Tx measurements (and optionally UL SRS-RSRP of the received signals) using assistance data received from the positioning server. The measurements are used to determine the RTT at the positioning server which are used to estimate the location of the UE. Multi- RTT may only be supported for UE-assisted / NG-RAN assisted positioning techniques.

[0041] Carrier Phase Based Positioning (CPP) (see TS 38.855 (incorporated herein by reference)) – CPP refers to the positioning method, where the transmitter (either the gNB or the UE) transmits the PRSs at the pre-configured carrier frequency, and the receiver (either the UE or the gNB) obtains the carrier phase measurements by tracking (TRS). Phase measurements may be derived from the complex correlations at the receiver side. The measurements combined with TDOA are used to estimate user position.

[0042] Enhanced Cell ID (E-CID) positioning method - the position of a UE is estimated with the knowledge of its serving ng-eNB, gNB and cell and is based on LTE signals. The information about the serving ng-eNB, gNB and cell may be obtained by paging, registration, or other methods. NR Enhanced Cell ID (NR E CID) positioningrefers to techniques which use additional UE measurements and / or NR radio resource and other measurements to improve the UE location estimate using NR signals. Although NR E-CID positioning may utilize some of the same measurements as the measurement control system in the radio resource control (RRC) protocol, the UE generally is not expected to make additional measurements for the sole purpose of positioning; i.e., the positioning procedures do not supply a measurement configuration or measurement control message, and the UE reports the measurements that it has available rather than being required to take additional measurement actions.

[0043] The UL TDOA positioning method makes use of the UL RTOA (and optionally UL SRS-RSRP) at multiple RPs of uplink signals transmitted from UE. The RPs measure the UL RTOA (and optionally UL SRS-RSRP) of the received signals using assistance data received from the positioning server, and the resulting measurements are used along with other configuration information to estimate the location of the UE.

[0044] The UL angle of arrival (AoA) positioning method makes use of the measured azimuth and the zenith of arrival at multiple RPs of uplink signals transmitted from UE. The RPs measure A-AoA and Z-AoA of the received signals using assistance data received from the positioning server, and the resulting measurements are used along with other configuration information to estimate the location of the UE.

[0045] Figure 2 illustrates an example of an architecture 200 for NR DL-based positioning measurements and RSs, in accordance with aspects of the present disclosure. Figure 2 shows the UE 202, the gNBs 204-208, and a location management function (LMF) 210. In various embodiments, the UE 202 is representative of a set of UEs 104 interacting with a set of NEs 102 (e.g., gNBs 204-208) and the LMF 210 is representative of a network function (NF) in the CN 106.

[0046] As depicted, the architecture 200 for NR DL-based positioning includes a UE 202 which may receive a DL PRS from a neighboring first gNB / TRP (denoted “gNB1–TRP1”) 204, from a neighboring second gNB (denoted “gNB2–TRP1”) 206, and also from a third gNB / TRP (denoted “gNB3–TRP1”) 208, which is a reference or serving gNB. The DL PRS can be transmitted by different base stations (e.g., serving gNB and neighboring gNB(s)) using narrow beams over Frequency Range #1 Between (“FR1”) (i.e., frequencies from 410 MHz to 7125 MHz) and Frequency Range #2(“FR2”) (i.e., frequencies from 24.25 GHz to 52.6 GHz), which is relatively different in NR when compared to LTE where the PRS was transmitted across the whole cell.

[0047] Here, the DL PRS can be locally associated with a DL PRS Resource Identifier (“ID”) and Resource Set ID for a base station (i.e., TRP). In the depicted embodiments, each gNB 204, 206, 208 is configured with a first Resource Set ID (depicted as “Resource Set ID#0”) 212 and a second Resource Set ID (depicted as “Resource Set ID#1”) 214. As depicted, the UE 202 receives DL PRS on transmission beams; here, receiving DL PRS from the gNB1–TRP1204 on DL PRS Resource ID #3 from the second Resource Set ID (“Resource Set ID#1”) 214, receiving DL PRS from the gNB2–TRP1206 on DL PRS Resource ID #3 from the first Resource Set ID (“Resource Set ID#0”) 212, and receiving DL PRS from the gNB3–TRP1208 on DL PRS Resource ID #1 from the second Resource Set ID (“Resource Set ID#1”) 214.

[0048] UE positioning measurements, such as Reference Signal Time Difference (RSTD) and PRS RSRP measurements, may be made between different beams (e.g., between a different pair of DL PRS resources or DL PRS resource sets). The LMF 210 uses the UE positioning measurements to determine the location (e.g., absolute position) of the UE 202. In addition, there are additional uplink (UL) positioning methods for the network to exploit in order to compute the location of the target UE 202.

[0049] Error! Reference source not found.The tables below show the RS to measurements mapping required for each of the supported RAT-dependent positioning techniques at the UE and gNB, respectively. RAT-dependent positioning techniques involve the 3GPP RAT and core network entities to perform the position estimation of the UE, which are differentiated from RAT-independent positioning techniques which rely on GNSS, IMU sensor, WLAN and Bluetooth technologies for performing target device (UE) positioning. DL / UL RSs UE Measurements To facilitate support of the following positioning techniques Rel.16 DL PRS DL RSTD DL-TDOA Rel.16 DL PRS DL PRS RSRP DL-TDOA, DL-AoD, Multi-RTT Rel.16 DL PRS / UE Rx-Tx time Multi-RTT Rel.16 SRS for difference positioning Rel.15 SSB / CSI-RS SS-RSRP(RSRP for E-CID for RRM RRM), SS-RSRQ(forRRM), CSI-RSRP (for RRM), CSI-RSRQ (for RRM), SS-RSRPB (for RRM) DL / UL RSs gNB Measurements To facilitate support of the following positioning techniques Rel.16 SRS for UL RTOA UL-TDOA positioning Rel.16 SRS for UL SRS-RSRP UL-TDOA, UL-AoA, positioning Multi-RTT Rel.16 SRS for gNB Rx-Tx time Multi-RTT positioning, Rel.16 difference DL PRS Rel.16 SRS for AoA and ZoA UL-AoA, Multi-RTT positioning,

[0050] As used herein, a DAS is a network of spatially separated antenna nodes connected to a common source via a transport medium that provides wireless service within a geographic area or structure. In certain embodiments, a DAS has two components, a signal source and a distribution system. A DAS, as the name implies, “distributes” a signal, but it generally doesn’t generate the cellular signal itself. A DAS needs to be fed signal from somewhere. Whether it's 4G LTE or 5G, there are a few typical signal sources: off-air (via an antenna on the roof), an on-site Base Transceiver Station (BTS), and small cells. Once received, the cellular signal must be distributed throughout the building. There are four main types of distribution systems: active (using fiber optic or ethernet cable), passive, hybrid, and digital.

[0051] Further, there are different RAT-dependent positioning measurements, including DL PRS-RSRP, DL RSTD and UE Rx-Tx Time Difference, which are described in more detail in the table below: DL PRS-RSRP Definition DL PRS-RSRP, is defined as the linear average over the power contributions (in 8) of the resource elements that carry DL PRS RSs configured for RSRP measurements within the considered measurement frequency bandwidth. For frequency range 1, the reference point for the DL PRS-RSRP shall be the antenna connector of the UE. For frequency range 2, DL PRS-RSRP shall be measured based on the combined signal from antenna elements corresponding to a given receiver branch. For frequency range 1 and 2, if receiver diversity isin use by the UE, the reported DL PRS-RSRP value shall not be lower than the corresponding DL PRS-RSRP of any of the individual receiver branches. Applicable RRC_CONNECTED intra-frequency, for RRC_CONNECTED inter-frequency DL RSTD Definition DL RSTD is the DL relative timing difference between the positioning node j and the reference positioning node i, defined as TSubframeRxj – TSubframeRxi, Where: TSubframeRxj is the time when the UE receives the start of one subframe from positioning node j. TSubframeRxi is the time when the UE receives the corresponding start of one subframe from positioning node i that is closest in time to the subframe received from positioning node j. Multiple DL PRS resources can be used to determine the start of one subframe from a positioning node. For frequency range 1, the reference point for the DL RSTD shall be the antenna connector of the UE. For frequency range 2, the reference point for the DL RSTD shall be the antenna of the UE. Applicable RRC_CONNECTED intra-frequency for RRC_CONNECTED inter-frequency UE Rx – Tx time difference Definition The UE Rx – Tx time difference is defined as TUE-RX– TUE-TXWhere: TUE-RX is the UE received timing of DL subframe #i from a positioning node, defined by the first detected path in time. TUE-TX is the UE transmit timing of uplink subframe #j that is closest in time to the subframe #i received from the positioning node. Multiple DL PRS resources can be used to determine the start of one subframe of the first arrival path of the positioning node. For frequency range 1, the reference point for TUE-RXmeasurement shall be the Rx antenna connector of the UE and the reference point for TUE-TXmeasurement shall be the Tx antenna connector of the UE. For frequency range 2, the reference point for TUE-RXmeasurement shall be the Rx antenna of the UE and the reference point for TUE-TX measurement shall be the Tx antenna of the UE. Applicable RRC_CONNECTED intra-frequency for RRC_CONNECTED inter-frequency

[0052] The subject matter herein details solutions to enhance positioning accuracy in limited-bandwidth scenarios using RF-coherent DAS. In one embodiment, this technique is valid for any RAT-dependent positioning techniques but proves more effectiveness for timing-based positioning techniques where a good time resolution is needed to achieve high positioning accuracies. Prior to transmitting DL PRS to a target UE, distributed antennas coordinate by locally transmitting RSs to synchronize theirphases, frequencies, and time. Consequently, DL PRS signals transmitted to a target UE would be RF-coherent.

[0053] The term “coherent” would normally denote a specified or controlled carrier phase. However, in the definition considered here, the term is intended to mean much more. For example, in transmit operations, multiple transmitters are used to generate RF signals whose properties are controlled to such a degree as to permit the precise generation of a desired electromagnetic field at a particular location in space and at a specified instant in time. Similarly, for receive operations, one or multiple receivers whose properties are controlled to such a degree that the received outputs for an arbitrary RF signal may be processed using coherent array processing techniques. However, certain objectives may further require precision location, precision timing, and precise knowledge of axial orientation.

[0054] This method does not exhibit large bandwidth PRS transmission to allow for high accuracy position estimation using timing-based positioning techniques. As described herein, high positioning accuracies may be reached by increasing the SNR of the PRS signal. The SNR could be increased without increasing the transmitting power, using an RF-coherent combination of multiple PRS signals transmitted from DASs.

[0055] More precisely, distributed antennas, used for target UE positioning, coordinate to synchronize their frequency, phase, and time before transmitting PRSs to a target UE. The resulting RF-coherent PRSs have much higher SNR, which allows higher accuracy at a target UE even if PRS bandwidth is limited.

[0056] In one embodiment described herein, distributed antennas are configured by an LMF or gNB to transmit DL / SL PRS to target UE to enable target UE to determine its location using RAT-dependent positioning techniques e.g., timing-based positioning techniques. Different distributed antennas / nodes coordinate to enable the transmission of RF-coherent PRS signal to target UE. To mitigate phase, frequency, and timing misalignments at transmitters, distributed antennas synchronize their frequency, phase and time by iteratively transmitting RSs between each other. This could be done in a centralized or distributed manner, as described below. The PRS signals received by target UE from the different distributed antennas are RF-coherent, in the sense that frequency and phase errors, such as frequency offsets, initial phases at transmitters, and timing synchronization errors, are mitigated at transmitters. This coordination betweendistributed nodes enables RF-coherent transmissions, which means that different signals from different nodes add constructively / coherently at receiver. This results in a high PRS SNR at receiver, which enables higher positioning accuracies even in bandwidth- limited scenarios. In one embodiment, this may be proved using CRLB.

[0057] In one embodiment, the number of distributed nodes / antennas participating in the positioning procedure as well as the PRS bandwidth may be adjusted to target a desired positioning accuracy and according to channel conditions. The PRS SNR (equivalent to number of nodes participating to the positioning procedure) and PRS bandwidth could be requested by UE. The request may be transmitted to an LMF or to a DAS-CU via LTE positioning protocol (LPP) / SLPP or RRC / PC5-RRC signalling. In one embodiment, LPP / SLPP is the signaling between 1) LMF and UE (LPP and SLPP) and 2) SLPP between UE and UE. RRC is between gNB and UE, while PC5 RRC is between UE and UE. A gNB may be composed of both CU and DU. In the case of UE, in one embodiment, e.g., it is assumed that both CU and DU reside within a vehicle.

[0058] For the purposes of this disclosure, a positioning-related RS may be referred to as a RS used for positioning procedures / purposes to estimate a target-UE’s location, e.g., PRS, or based on existing RSs such as channel state information (CSI)-RS or sounding reference signal (SRS) or a new RS for carrier phase positioning. A target-UE may be referred to as the device / entity to be localized / positioned. In various embodiments, the term PRS may refer to any signal such as a RS, which may or may not be used primarily for positioning. In certain embodiments, distributed nodes have a perfect knowledge of their positions with zero uncertainty.

[0059] In one embodiment, the subject matter disclosed herein is useful for limited bandwidth scenarios and in scenarios where stringent positioning accuracies are required. The solutions use techniques that allow higher SNR at a receiver without increasing PRS transmitting power at transmitters. The solutions use an RF-coherent combination of DASs.

[0060] In one embodiment, for timing-based positioning techniques, time resolution of the received DL PRS / UL SRS and SL PRS signals is high to get high target UE positioning accuracy, which is proportional to the signal transmission bandwidth. This is possible when using large PRS bandwidths e.g., 100 MHz. However, these large bandwidths may not be guaranteed due to spectrum scarcity. One alternative to reachhigh positioning accuracies is to maximize SNR at the receiver. From a theoretical perspective, this could be proved using the CRLB on the ranging error variances for timing-based positioning techniques e.g., TDoA, which is defined in the equation below.

[0061] Figure 3 depicts a graph 300 that shows the CRLB for different PRS bandwidths and different SNR ranges in accordance with aspects of the present disclosure. CRLB shows that the accuracy of timing-based positioning methods depends on the RS bandwidth and the PRS SNR. ^^^^^(^) ≥^^^^^^ ∗ ^^^^

[0062] where^^^^^^=^^^ (^^^^^)square bandwidth of the signal a ^|^(^)|^^^nd ^ ^(^) is , c is the speed of light and SNR is theSNR of the transmitted PRS.

[0063] According to the CRLB, in bandwidth-limited cases, high positioning accuracies are possible if the lower bandwidths are compensated by maximizing the SNR. However, when considering one transmitting antenna, SNR is limited by maximum allowed transmitting power and antenna gain. This issue could be confronted using distributed antennas and RF-coherent combining of different DL / SL PRS signals transmitted from different Tx distributed antennas. RF-coherence of transmitted signal could be attained by coordination between distributed antennas.

[0064] Figure 4 depicts an example of an RF-coherent PRS transmission, in accordance with aspects of the present disclosure. In this network setup, each node 402- 406 has its own local oscillator in its transceiver chain, and thus synchronizing the transceivers of the nodes implies synchronizing the frequencies and phases of the signals generated by these oscillators. The stability of the local oscillator is the primary factor that affects the synchronization of these transceivers. Due to the manufacturing tolerances and temperature variations, these oscillators undergo random frequency drift and phase jitters over the time that offsets the frequency and phases of their generated signals.

[0065] In the considered network setup shown in Figure 3, DASs could be split according to functional splits option 1 or option 2 as presented in the table below. RF chains are, according to this setup, contained within the DU along with antennas: Option 0 (Antenna- Only antennas are in the DUs and the other functionalities are in RF Split) the CUs Extending the (copper) cabling between the antenna and RF unit is the most common solution when the antenna and RF unit are not in the same place. Option 1 (RF-PHY Antennas and RF are in the DU and the other functionalities are Split) in the CU The cable loss can be reduced when the RF signal is converted to intermediate frequency band, however cable length remains a limitation in the system design. Option 2 Antennas, RF and ADC / DAC are in the DU and the other (RF+ADC / DAC- functionalities are in the CU Time-domain I / Q samples are PHY Split) transmitted via the interface between CU and DU

[0066] Without phase, frequency, and timing synchronization at transmitters, the ^^symbol at the !^subcarrier received from the "^node at the target UE can be given by ^#,%,&= (#,%,&)*(^^^+(,-.^-). / 01. 234,5,-)+ 7#,%

[0067] where98is the carrier wavelength, :&is the propagation delay from node " to target UE. ;<=is the initial phase at receiver / target UE, ^&is the timing offset between transmitters, and the phase error >?#,%,&defined as >?#,%,&= 2A>^#,%,&B + >^#,%,&+ ;#C,%,&+ >;#,%,&

[0068] where 2A>^#,%,&B is the phase error due to the frequency offset >^#,%,&of the oscillator in the l-th node at the update time T; ;#C,%,&is a constant phase term assumed herein to be uniformly distributed between 0 to 2π and accounting for the estimation error in the distance and orientation angle of the l-th node, a residual phase error due to the timing misalignment, a hardware or channel induced phase delay, and a phase error due to the mismatch of antennas radiation pattern, etc.; >^#,%,&represents the phase error due to the time variation of the frequency of the oscillator within the update interval; >;#,%,&is the error due to the random phase jitter of the oscillator in the i-th node.

[0069] Frequency, phase, and timing offsets between transmitters may be mitigated if distributed antennas (also referred as distributed nodes) are configured to synchronize their oscillator’s frequency and phase as well as the timing errors prior to transmittingDL / SL PRSs to target UE. According to a first implementation, the nodes’ coordination architecture could be fully distributed, requiring no centralization. In this case, the distributed nodes enable a local broadcast of their signals to share their frequencies and phases with the neighbouring nodes and align these parameters. Each distributed node iteratively updates its frequency and phase by computing an average of the frequencies and phases of the other nodes. It is assumed that each node can estimate the frequencies and phases of its neighbouring nodes from the received signals, for instance, by using the fast Fourier transform based maximum likelihood estimator.

[0070] In one embodiment, the algorithm converges and can align the frequencies and phases of all the nodes up to a residual phase error that is governed by the oscillators and the estimation errors. To reduce this residual phase error and thus improve the synchronization between the nodes, other techniques, for example Kalman filtering, could be used. The nodes align their transceivers within the fraction of the wavelength of wireless operation in such a way that their signals add up coherently at the destination. The distributed nodes coordinate with each other to synchronize their transceivers without using any feedback from the destination / target UE. Consider, for example, a network of N nodes spatially separated by multiples of wavelength and coordinating with each other to synchronize their frequency, phase, and timing offsets. Each node has a local oscillator, and a signal model is considered where intrinsic frequency and phase errors of the local oscillators on each node caused by the frequency drift and phase jitter as well as the frequency and phase estimation errors at the nodes are included and modelled using practical statistics.

[0071] Consider, for example, a network of N nodes spatially separated by multiples of the wavelength of coherent operation and coordinating with each other using techniques as described above to form a coherent beam in a given direction. At receiver / target UE, the signal received in their mutual far-field can be given by J *^^ ^F GHI

[0072] where C frequency of the coherent operation and 98is its wavelength, ^Kand ;Kare the distance and orientation angle of the n-th node relative to a reference point or node and N is an additive white gaussian noise (AWGN) that has a variance O^: P(0, O^).

[0073] In one embodiment, the SNR of the received signal could be determined as follows: ^^^ =S U ^^T [^ ]^=O^

[0074] The received signalas follows: J U[^^]= D SX,K^ ^ `

[0075] In onenodes used for target UE positioning, the higher the SNR. And as proved above, a better positioning accuracy can be achieved.

[0076] In one implementation, the receiver / target UE could perform super- resolution techniques such as MUSIC, ESPRIT, or the like to detect the ToA. In another implementation, more advanced techniques could be used, such as a steered covariance matrix-based MUSIC-type (SCM-MUSIC) algorithm for wideband direct position estimation.

[0077] According to a second embodiment, a target UE could be configured to report the desired positioning accuracy level to LMF via LPP signaling. In this case, LMF would configure DAS-CU to adjust PRS transmissions and number of nodes based on the desired SNR. According to another embodiment, in scenarios where spectrum is available and larger bandwidths could be further harnessed, the number of participating nodes in the positioning procedure to reach certain SNR value as well as PRS bandwidth could be configured and fine-tuned based on target UE feedback and the service target requirements. Target UE could update its feedback based on varying channel conditions, required positioning accuracy, positioning uncertainty level, and / or the like.

[0078] According to a first implementation, a target UE could be configured to request an on-demand SL / DL PRS received power based on some requirements including the desired accuracy, allowed uncertainty level, and / or the like. These requested SL / DL PRS parameters, which might also include a couple (PRS bandwidth, PRS signal power) are reported to the LMF or directly to DAS-CU via LPP / SLPP or via RRC / PC5-RRC signaling. LMF or CU, upon reception of the requested PRS parameters, could tune / adjust a number of nodes participating in the positioning procedure and / or PRS bandwidth or a combination thereof.

[0079] In an alternate implementation, target UE could determine the desired and sufficient SNR by performing different measurements over the channel e.g., RSRP, received signal strength indicator (RSSI), received signal received quality (RSRQ), and / or the like. In this case, target UE might also request LMF or DAS-CU to enable a smaller number of distributed nodes (to decrease SNR, if the channel conditions improve and target accuracy could be reached using lower SNR ranges) or enable lower PRS bandwidth, or a combination thereof.

[0080] Figure 5 illustrates an example of a UE 500 in accordance with aspects of the present disclosure. The UE 500 may include a processor 502, a memory 504, a controller 506, and a transceiver 508. The processor 502, the memory 504, the controller 506, or the transceiver 508, or various combinations thereof or various components thereof may be examples of means for performing various aspects of the present disclosure as described herein. These components may be coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more interfaces.

[0081] The processor 502, the memory 504, the controller 506, or the transceiver 508, or various combinations or components thereof may be implemented in hardware (e.g., circuitry). The hardware may include a processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), or other programmable logic device, or any combination thereof configured as or otherwise supporting a means for performing the functions described in the present disclosure.

[0082] The processor 502 may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, a CPU, an ASIC, an FPGA, or any combination thereof). In some implementations, the processor 502 may be configured to operate thememory 504. In some other implementations, the memory 504 may be integrated into the processor 502. The processor 502 may be configured to execute computer-readable instructions stored in the memory 504 to cause the UE 500 to perform various functions of the present disclosure.

[0083] The memory 504 may include volatile or non-volatile memory. The memory 504 may store computer-readable, computer-executable code including instructions when executed by the processor 502 cause the UE 500 to perform various functions described herein. The code may be stored in a non-transitory computer-readable medium such the memory 504 or another type of memory. Computer-readable media includes both non-transitory computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A non-transitory storage medium may be any available medium that may be accessed by a general-purpose or special-purpose computer.

[0084] In some implementations, the processor 502 and the memory 504 coupled with the processor 502 may be configured to cause the UE 500 to perform one or more of the functions described herein (e.g., executing, by the processor 502, instructions stored in the memory 504). For example, the processor 502 may support wireless communication at the UE 500 in accordance with examples as disclosed herein. The UE 500 may be configured to support a means to receive an RF-coherent PRS from each of a plurality of DUs for estimating a location of the UE, the coherent PRS allowing a higher SNR for estimating the location, perform measurements over the received RF- coherent PRSs according to a configured positioning technique, estimate the location of the UE based on the RF-coherent PRS received from each of the plurality of DUs in a UE-based positioning scenario, and transmit the estimated location measurements to an NE in a network-based positioning scenario.

[0085] In one embodiment, the UE 500 may be configured to support a means to dynamically transmit a request for a PRS bandwidth, an SNR, or a combination thereof based on a desired positioning accuracy or a channel condition.

[0086] In one embodiment, the UE 500 may be configured to support a means to estimate the location of the UE using a timing-based positioning technique based on a SNR of the RF-coherent PRS.

[0087] In one embodiment, the UE 500 may be configured to support a means to estimate a TOA using a super-resolution measurement algorithm for estimating the location of the UE.

[0088] The controller 506 may manage input and output signals for the UE 500. The controller 506 may also manage peripherals not integrated into the UE 500. In some implementations, the controller 506 may utilize an operating system such as iOS®, ANDROID®, WINDOWS®, or other operating systems. In some implementations, the controller 506 may be implemented as part of the processor 502.

[0089] In some implementations, the UE 500 may include at least one transceiver 508. In some other implementations, the UE 500 may have more than one transceiver 508. The transceiver 508 may represent a wireless transceiver. The transceiver 508 may include one or more receiver chains 510, one or more transmitter chains 512, or a combination thereof.

[0090] A receiver chain 510 may be configured to receive signals (e.g., control information, data, packets) over a wireless medium. For example, the receiver chain 510 may include one or more antennas for receiving the signal over the air or wireless medium. The receiver chain 510 may include at least one amplifier (e.g., a low-noise amplifier (LNA)) configured to amplify the received signal. The receiver chain 510 may include at least one demodulator configured to demodulate the received signal and obtain the transmitted data by reversing the modulation technique applied during transmission of the signal. The receiver chain 510 may include at least one decoder for decoding the demodulated signal to receive the transmitted data.

[0091] A transmitter chain 512 may be configured to generate and transmit signals (e.g., control information, data, packets). The transmitter chain 512 may include at least one modulator for modulating data onto a carrier signal, preparing the signal for transmission over a wireless medium. The at least one modulator may be configured to support one or more techniques such as amplitude modulation (AM), frequency modulation (FM), or digital modulation schemes like phase-shift keying (PSK) or quadrature amplitude modulation (QAM). The transmitter chain 512 may also include at least one power amplifier configured to amplify the modulated signal to an appropriate power level suitable for transmission over the wireless medium. The transmitter chain512 may also include one or more antennas for transmitting the amplified signal into the air or wireless medium.

[0092] Figure 6 illustrates an example of a processor 600 in accordance with aspects of the present disclosure. The processor 600 may be an example of a processor configured to perform various operations in accordance with examples as described herein. The processor 600 may include a controller 602 configured to perform various operations in accordance with examples as described herein. The processor 600 may optionally include at least one memory 604, which may be, for example, an L1 / L2 / L3 cache. Additionally, or alternatively, the processor 600 may optionally include one or more arithmetic-logic units (ALUs) 606. One or more of these components may be in electronic communication or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more interfaces (e.g., buses).

[0093] The processor 600 may be a processor chipset and include a protocol stack (e.g., a software stack) executed by the processor chipset to perform various operations (e.g., receiving, obtaining, retrieving, transmitting, outputting, forwarding, storing, determining, identifying, accessing, writing, reading) in accordance with examples as described herein. The processor chipset may include one or more cores, one or more caches (e.g., memory local to or included in the processor chipset (e.g., the processor 600) or other memory (e.g., random access memory (RAM), read-only memory (ROM), dynamic RAM (DRAM), synchronous dynamic RAM (SDRAM), static RAM (SRAM), ferroelectric RAM (FeRAM), magnetic RAM (MRAM), resistive RAM (RRAM), flash memory, phase change memory (PCM), and others).

[0094] The controller 602 may be configured to manage and coordinate various operations (e.g., signaling, receiving, obtaining, retrieving, transmitting, outputting, forwarding, storing, determining, identifying, accessing, writing, reading) of the processor 600 to cause the processor 600 to support various operations in accordance with examples as described herein. For example, the controller 602 may operate as a control unit of the processor 600, generating control signals that manage the operation of various components of the processor 600. These control signals include enabling or disabling functional units, selecting data paths, initiating memory access, and coordinating timing of operations.

[0095] The controller 602 may be configured to fetch (e.g., obtain, retrieve, receive) instructions from the memory 604 and determine subsequent instruction(s) to be executed to cause the processor 600 to support various operations in accordance with examples as described herein. The controller 602 may be configured to track memory address of instructions associated with the memory 604. The controller 602 may be configured to decode instructions to determine the operation to be performed and the operands involved. For example, the controller 602 may be configured to interpret the instruction and determine control signals to be output to other components of the processor 600 to cause the processor 600 to support various operations in accordance with examples as described herein. Additionally, or alternatively, the controller 602 may be configured to manage flow of data within the processor 600. The controller 602 may be configured to control transfer of data between registers, arithmetic logic units (ALUs), and other functional units of the processor 600.

[0096] The memory 604 may include one or more caches (e.g., memory local to or included in the processor 600 or other memory, such RAM, ROM, DRAM, SDRAM, SRAM, MRAM, flash memory, etc. In some implementations, the memory 604 may reside within or on a processor chipset (e.g., local to the processor 600). In some other implementations, the memory 604 may reside external to the processor chipset (e.g., remote to the processor 600).

[0097] The memory 604 may store computer-readable, computer-executable code including instructions that, when executed by the processor 600, cause the processor 600 to perform various functions described herein. The code may be stored in a non- transitory computer-readable medium such as system memory or another type of memory. The controller 602 and / or the processor 600 may be configured to execute computer-readable instructions stored in the memory 604 to cause the processor 600 to perform various functions. For example, the processor 600 and / or the controller 602 may be coupled with or to the memory 604, the processor 600, the controller 602, and the memory 604 may be configured to perform various functions described herein. In some examples, the processor 600 may include multiple processors and the memory 604 may include multiple memories. One or more of the multiple processors may be coupled with one or more of the multiple memories, which may, individually or collectively, be configured to perform various functions herein.

[0098] The one or more ALUs 606 may be configured to support various operations in accordance with examples as described herein. In some implementations, the one or more ALUs 606 may reside within or on a processor chipset (e.g., the processor 600). In some other implementations, the one or more ALUs 606 may reside external to the processor chipset (e.g., the processor 600). One or more ALUs 606 may perform one or more computations such as addition, subtraction, multiplication, and division on data. For example, one or more ALUs 606 may receive input operands and an operation code, which determines an operation to be executed. One or more ALUs 606 be configured with a variety of logical and arithmetic circuits, including adders, subtractors, shifters, and logic gates, to process and manipulate the data according to the operation. Additionally, or alternatively, the one or more ALUs 606 may support logical operations such as AND, OR, exclusive-OR (XOR), not-OR (NOR), and not-AND (NAND), enabling the one or more ALUs 606 to handle conditional operations, comparisons, and bitwise operations.

[0099] The processor 600 may support wireless communication in accordance with examples as disclosed herein. The processor 600 may be configured to or operable to support a means to transmit an RS to a plurality of DUs for synchronization between each of the plurality of DUs, mitigate a synchronization offset between each of the plurality of DUs, and transmit an RF-coherent PRS, based on the synchronization, to a target device for estimating a location of the target device, the coherent PRS allowing a higher SNR for estimating the location.

[0100] In one embodiment, the synchronization comprises a synchronization of a phase, a frequency, a timing, or a combination thereof between each of the plurality of DUs. In one embodiment, the synchronization offset comprises a phase offset, a frequency offset, a timing offset, or a combination thereof between each of the plurality of DU.

[0101] In one embodiment, the processor 600 and the plurality of DUs are under control of a CU. In one embodiment, the processor 600 and the plurality of DUs comprise distributed antennas that are under control of a same CU and the target device comprises a target UE device.

[0102] In one embodiment, the processor 600 may be configured to or operable to support a means to mitigate the synchronization offset error by locally broadcasting RSswithin a distributed topology scenario. In one embodiment, the processor 600 may be configured to or operable to support a means to mitigate the synchronization offset error by locking a frequency or a phase of each of the plurality of DUs to an oscillator frequency or phase of a master DU.

[0103] In one embodiment, a signal comprising a combination of the RF-coherent PRSs transmitted from the plurality of DUs to the target device has a higher SNR than a single PRS. In one embodiment, the processor 600 may be configured to or operable to support a means to configure a PRS bandwidth, the PRS SNR, or a combination thereof based on a desired positioning accuracy for the target device.

[0104] In one embodiment, the processor 600 may be configured to or operable to support a means to dynamically receive a request for a PRS bandwidth, the PRS SNR, or a combination thereof from the target device based on a desired positioning accuracy, a channel condition, or a combination thereof.

[0105] In one embodiment, the processor 600 may be configured to or operable to support a means to transmit the RF-coherent PRS according to a request for a PRS bandwidth, a PRS SNR, or a combination thereof and adjust the transmitted RF- coherent PRS based on the request.

[0106] In one embodiment, the processor 600 may be configured to or operable to support a means to configure a PRS bandwidth, the SNR, or a combination thereof based on feedback from a target UE and according to a desired positioning accuracy for the target device, a channel condition, or a combination thereof.

[0107] Figure 7 illustrates an example of a NE 700 in accordance with aspects of the present disclosure. The NE 700 may include a processor 702, a memory 704, a controller 706, and a transceiver 708. The processor 702, the memory 704, the controller 706, or the transceiver 708, or various combinations thereof or various components thereof may be examples of means for performing various aspects of the present disclosure as described herein. These components may be coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more interfaces.

[0108] The processor 702, the memory 704, the controller 706, or the transceiver 708, or various combinations or components thereof may be implemented in hardware(e.g., circuitry). The hardware may include a processor, a digital signal processor (DSP), an ASIC, or other programmable logic device, or any combination thereof configured as or otherwise supporting a means for performing the functions described in the present disclosure.

[0109] The processor 702 may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, a CPU, an ASIC, an FPGA, or any combination thereof). In some implementations, the processor 702 may be configured to operate the memory 704. In some other implementations, the memory 704 may be integrated into the processor 702. The processor 702 may be configured to execute computer-readable instructions stored in the memory 704 to cause the NE 700 to perform various functions of the present disclosure.

[0110] The memory 704 may include volatile or non-volatile memory. The memory 704 may store computer-readable, computer-executable code including instructions when executed by the processor 702 to cause the NE 700 to perform various functions described herein. The code may be stored in a non-transitory computer-readable medium such the memory 704 or another type of memory. Computer-readable media includes both non-transitory computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A non-transitory storage medium may be any available medium that may be accessed by a general-purpose or special-purpose computer.

[0111] In some implementations, the processor 702 and the memory 704 coupled with the processor 702 may be configured to cause the NE 700 to perform one or more of the functions described herein (e.g., executing, by the processor 702, instructions stored in the memory 704). For example, the processor 702 may support wireless communication at the NE 700 in accordance with examples as disclosed herein. The NE 700 may be configured to support a means to transmit an RS to a plurality of DUs for synchronization between each of the plurality of DUs, mitigate a synchronization offset between each of the plurality of DUs, and transmit an RF-coherent PRS, based on the synchronization, to a target device for estimating a location of the target device, the coherent PRS allowing a higher SNR for estimating the location.

[0112] In one embodiment, the synchronization comprises a synchronization of a phase, a frequency, a timing, or a combination thereof between each of the plurality ofDUs. In one embodiment, the synchronization offset comprises a phase offset, a frequency offset, a timing offset, or a combination thereof between each of the plurality of DU.

[0113] In one embodiment, the NE 700 and the plurality of DUs are under control of a CU. In one embodiment, the NE 700 and the plurality of DUs comprise distributed antennas that are under control of a same CU and the target device comprises a target UE device.

[0114] In one embodiment, the NE 700 may be configured to support means to mitigate the synchronization offset by locally broadcasting RSs within a distributed topology scenario. In one embodiment, the NE 700 may be configured to support means to mitigate the synchronization offset by locking a frequency or a phase of each of the plurality of DUs to an oscillator frequency or phase of a master DU.

[0115] In one embodiment, a signal comprising a combination of the RF-coherent PRSs transmitted from the plurality of DUs to the target device has a higher SNR than a single PRS. In one embodiment, the NE 700 may be configured to support means to configure a PRS bandwidth, the PRS SNR, or a combination thereof based on a desired positioning accuracy for the target device.

[0116] In one embodiment, the NE 700 may be configured to support means to transmit the RF-coherent PRS according to a request for a PRS bandwidth, a PRS SNR, or a combination thereof and adjust the transmitted RF-coherent PRS based on the request.

[0117] In one embodiment, the NE 700 may be configured to support means to configure a PRS bandwidth, the SNR, or a combination thereof based on feedback from a target UE and according to a desired positioning accuracy for the target device, a channel condition, or a combination thereof.

[0118] The controller 706 may manage input and output signals for the NE 700. The controller 706 may also manage peripherals not integrated into the NE 700. In some implementations, the controller 706 may utilize an operating system such as iOS®, ANDROID®, WINDOWS®, or other operating systems. In some implementations, the controller 706 may be implemented as part of the processor 702.

[0119] In some implementations, the NE 700 may include at least one transceiver 708. In some other implementations, the NE 700 may have more than one transceiver 708. The transceiver 708 may represent a wireless transceiver. The transceiver 708 may include one or more receiver chains 710, one or more transmitter chains 712, or a combination thereof.

[0120] A receiver chain 710 may be configured to receive signals (e.g., control information, data, packets) over a wireless medium. For example, the receiver chain 710 may include one or more antennas for receiving the signal over the air or wireless medium. The receiver chain 710 may include at least one amplifier (e.g., a low-noise amplifier (LNA)) configured to amplify the received signal. The receiver chain 710 may include at least one demodulator configured to demodulate the received signal and obtain the transmitted data by reversing the modulation technique applied during transmission of the signal. The receiver chain 710 may include at least one decoder for decoding and processing the demodulated signal to receive the transmitted data.

[0121] A transmitter chain 712 may be configured to generate and transmit signals (e.g., control information, data, packets). The transmitter chain 712 may include at least one modulator for modulating data onto a carrier signal, preparing the signal for transmission over a wireless medium. The at least one modulator may be configured to support one or more techniques such as amplitude modulation (AM), frequency modulation (FM), or digital modulation schemes like phase-shift keying (PSK) or quadrature amplitude modulation (QAM). The transmitter chain 712 may also include at least one power amplifier configured to amplify the modulated signal to an appropriate power level suitable for transmission over the wireless medium. The transmitter chain 712 may also include one or more antennas for transmitting the amplified signal into the air or wireless medium.

[0122] Figure 8 illustrates a flowchart of a method in accordance with aspects of the present disclosure. The operations of the method may be implemented by a NE as described herein. In some implementations, the NE may execute a set of instructions to control the function elements of the NE to perform the described functions.

[0123] At 802, the method may transmit an RS to a plurality of DUs for synchronization between each of the plurality of DUs. The operations of 802 may be performed in accordance with examples as described herein. In some implementations,aspects of the operations of 802 may be performed by a NE as described with reference to Figure 7.

[0124] At 804, the method may mitigate a synchronization offset between each of the plurality of DUs. The operations of 804 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 804 may be performed by a NE as described with reference to Figure 7.

[0125] At 806, the method may transmit an RF-coherent PRS, based on the synchronization, to a target device for estimating a location of the target device, the coherent PRS allowing a higher SNR for estimating the location. The operations of 806 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 806 may be performed by a NE as described with reference to Figure 7.

[0126] It should be noted that the method described herein describes a possible implementation, and that the operations and the steps may be rearranged or otherwise modified and that other implementations are possible.

[0127] Figure 9 illustrates a flowchart of a method in accordance with aspects of the present disclosure. The operations of the method may be implemented by a UE as described herein. In some implementations, the UE may execute a set of instructions to control the function elements of the UE to perform the described functions.

[0128] At 902, the method may receive an RF-coherent PRS from each of a plurality of DUs for estimating a location of the UE, the coherent PRS allowing a higher SNR for estimating the location. The operations of 902 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 902 may be performed by a UE as described with reference to Figure 5.

[0129] At 904, the method may perform measurements over the received RF- coherent PRSs according to a configured positioning technique. The operations of 904 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 904 may be performed by a UE as described with reference to Figure 5.

[0130] At 906, the method may estimate the location of the UE based on the RF- coherent PRS received from each of the plurality of DUs in a UE-based positioningscenario. The operations of 906 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 906 may be performed a UE as described with reference to Figure 5.

[0131] At 908, the method may transmit the estimated location measurements to a NE in a network-based positioning scenario. The operations of 908 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 908 may be performed a UE as described with reference to Figure 5.

[0132] It should be noted that the method described herein describes A possible implementation, and that the operations and the steps may be rearranged or otherwise modified and that other implementations are possible.

[0133] The description herein is provided to enable a person having ordinary skill in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to a person having ordinary skill in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not limited to the examples and designs described herein but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.

Claims

CLAIMS What is claimed is:

1. A network equipment (NE) for wireless communication, comprising: at least one memory; and at least one processor coupled with the at least one memory and configured to cause the NE to: transmit a reference signal (RS) to a plurality of distributed units (DUs) for synchronization between each of the plurality of DUs; mitigate a synchronization offset between each of the plurality of DUs; and transmit a radio frequency (RF)-coherent positioning RS (PRS), based on the synchronization, to a target device for estimating a location of the target device, the coherent PRS allowing a higher signal-to-noise ratio (SNR) for estimating the location.

2. The NE of claim 1, wherein the synchronization comprises a synchronization of a phase, a frequency, a timing, or a combination thereof between each of the plurality of DUs.

3. The NE of claim 1, wherein the synchronization offset comprises a phase offset, a frequency offset, a timing offset, or a combination thereof between each of the plurality of DU.

4. The NE of claim 1, wherein the NE and the plurality of DUs are under control of a central unit (CU).

5. The NE of claim 1, wherein the NE and the plurality of DUs comprise distributed antennas that are under control of a same central unit (CU) and the target device comprises a target user equipment (UE).

6. The NE of claim 1, wherein the at least one processor is configured to cause the NE to mitigate the synchronization offset by locally broadcasting RSs within a distributed topology scenario.

7. The NE of claim 1, wherein the at least one processor is configured to cause the NE to mitigate the synchronization offset by locking a frequency or a phase of each of the plurality of DUs to an oscillator frequency or phase of a master DU.

8. The NE of claim 1, wherein a signal comprising a combination of the RF- coherent PRSs transmitted from the plurality of DUs to the target device has a higher SNR than a single PRS.

9. The NE of claim 1, wherein the at least one processor is configured to cause the NE to configure a PRS bandwidth, a PRS SNR, or a combination thereof based on a desired positioning accuracy for the target device.

10. The NE of claim 1, wherein the at least one processor is configured to cause the NE to dynamically receive a request for a PRS bandwidth, a PRS SNR, or a combination thereof from the target device based on a desired positioning accuracy, a channel condition, or a combination thereof.

11. The NE of claim 1, wherein the at least one processor is configured to cause the NE to transmit the RF-coherent PRS according to a request for a PRS bandwidth, a PRS SNR, or a combination thereof and adjust the transmitted RF- coherent PRS based on the request.

12. The NE of claim 1, wherein the at least one processor is configured to cause the NE to configure a PRS bandwidth, the SNR, or a combination thereof based on feedback from a target user equipment (UE) and according to a desired positioning accuracy for the target device, a channel condition, or a combination thereof.

13. A processor for wireless communication, comprising: at least one controller coupled with at least one memory and configured to cause the processor to: transmit a reference signal (RS) to a plurality of distributed units (DUs) for synchronization between each of the plurality of DUs; mitigate a synchronization offset between each of the plurality of DUs; andtransmit a radio frequency (RF)-coherent positioning RS (PRS), based on the synchronization, to a target device for estimating a location of the target device, the coherent PRS allowing a higher signal-to-noise ratio (SNR) for estimating the location.

14. The processor of claim 13, wherein the synchronization comprises a synchronization of a phase, a frequency, a timing, or a combination thereof between each of the plurality of DUs.

15. The processor of claim 13, wherein the synchronization offset comprises a phase offset, a frequency offset, a timing offset, or a combination thereof between each of the plurality of DU.

16. A method performed by a network equipment (NE), the method comprising: transmitting a reference signal (RS) to a plurality of distributed units (DUs) for synchronization between each of the plurality of DUs; mitigating a synchronization offset between each of the plurality of DUs; and transmitting a radio frequency (RF)-coherent positioning RS (PRS), based on the synchronization, to a target device for estimating a location of the target device, the coherent PRS allowing a higher signal-to-noise ratio (SNR) for estimating the location.

17. A user equipment (UE) for wireless communication, comprising: at least one memory; and at least one processor coupled with the at least one memory and configured to cause the UE to: receive a radio frequency (RF)-coherent positioning reference signal (PRS) from each of a plurality of distributed units (DUs) for estimating a location of the UE, the RF- coherent PRS allowing a higher signal-to-noise ratio (SNR) for estimating the location; perform measurements over the received RF-coherent PRSs according to a configured positioning technique;estimate the location of the UE based on the RF-coherent PRS received from each of the plurality of DUs in a UE-based positioning scenario; and transmit the estimated location to a network equipment (NE) in a network-based positioning scenario.

18. The UE of claim 17, wherein the at least one processor is configured to cause the UE to dynamically transmit a request for a PRS bandwidth, an SNR, or a combination thereof based on a desired positioning accuracy or a channel condition.

19. The UE of claim 17, wherein the at least one processor is configured to cause the UE to estimate the location of the UE using a timing-based positioning technique based on a SNR of the RF-coherent PRS.

20. The UE of claim 17, wherein the at least one processor is configured to cause the UE to estimate a time-of-arrival (TOA) using a super-resolution measurement algorithm for estimating the location of the UE.

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