Measurement of a downlink positioning reference signal from a non-serving base station of a user equipment at a serving base station of the user equipment

In an aspect, a serving BS of a UE measures ToAs of a DL-PRS from a non-serving base station of the UE and an UL-SRS-P from the UE. The serving BS transmits measurement information based on the ToA measurements of the DL-PRS and the UL-SRS-P to a position estimation entity. The position estimation entity determines a positioning estimate for the UE based in part upon the measurement information.

BACKGROUND OF THE DISCLOSURE

1. Field of the Disclosure

Aspects of the disclosure relate generally to wireless communications, and more particularly to with measurement of a downlink positioning reference signal (DL-PRS) from a non-serving base station of a user equipment (UE) at a serving base station of the UE.

2. Description of the Related Art

SUMMARY

In an aspect, a method of operating a serving base station of a user equipment (UE) includes measuring a time of arrival (ToA) of a first downlink positioning reference signal (DL-PRS) from a non-serving base station of the UE; measuring a ToA of an uplink sounding reference signal for positioning (UL-SRS-P) from the UE that is transmitted in association with a second DL-PRS from the non-serving base station of the UE; and transmitting measurement information based on the ToA measurements of the first DL-PRS and the UL-SRS-P to a position estimation entity.

In an aspect, a method of operating a position estimation entity includes receiving, from a serving base station of a user equipment (UE), first measurement information indicative of a first time differential between a time of arrival (ToA) of a first downlink positioning reference signal (DL-PRS) from a non-serving base station of the UE as measured the serving base station, and a ToA of an uplink sounding reference signal for positioning (UL-SRS-P) from the UE as measured the serving base station; receiving, from the UE, second measurement information indicative of a second time differential between a ToA of second DL-PRS from the non-serving base station of the UE as measured at the UE and a time of transmission of the UL-SRS-P as measured at the UE; and determining a positioning estimate of the UE based at least in part upon the first measurement information and the second measurement information.

In an aspect, a serving base station of a user equipment (UE) includes a memory; at least one transceiver; and at least one processor communicatively coupled to the memory and the at least one transceiver, the at least one processor configured to: measure a time of arrival (ToA) of a first downlink positioning reference signal (DL-PRS) from a non-serving base station of the UE; measure a ToA of an uplink sounding reference signal for positioning (UL-SRS-P) from the UE that is transmitted in association with a second DL-PRS from the non-serving base station of the UE; and transmit, via the at least one transceiver, measurement information based on the ToA measurements of the first DL-PRS and the UL-SRS-P to a position estimation entity.

In an aspect, a position estimation entity includes a memory; at least one transceiver; and at least one processor communicatively coupled to the memory and the at least one transceiver, the at least one processor configured to: receive, via the at least one transceiver, from a serving base station of a user equipment (UE), first measurement information indicative of a first time differential between a time of arrival (ToA) of a first downlink positioning reference signal (DL-PRS) from a non-serving base station of the UE as measured the serving base station, and a ToA of an uplink sounding reference signal for positioning (UL-SRS-P) from the UE as measured the serving base station; receive, via the at least one transceiver, from the UE, second measurement information indicative of a second time differential between a ToA of second DL-PRS from the non-serving base station of the UE as measured at the UE and a time of transmission of the UL-SRS-P as measured at the UE; and determine a positioning estimate of the UE based at least in part upon the first measurement information and the second measurement information.

DETAILED DESCRIPTION

An “RF signal” comprises an electromagnetic wave of a given frequency that transports information through the space between a transmitter and a receiver. As used herein, a transmitter may transmit a single “RF signal” or multiple “RF signals” to a receiver. However, the receiver may receive multiple “RF signals” corresponding to each transmitted RF signal due to the propagation characteristics of RF signals through multipath channels. The same transmitted RF signal on different paths between the transmitter and receiver may be referred to as a “multipath” RF signal.

The base stations102may collectively form a RAN and interface with a core network170(e.g., an evolved packet core (EPC) or next generation core (NGC)) through backhaul links122, and through the core network170to one or more location servers172. In addition to other functions, the base stations102may perform functions that relate to one or more of transferring user data, radio channel ciphering and deciphering, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection setup and release, load balancing, distribution for non-access stratum (NAS) messages, NAS node selection, synchronization, RAN sharing, multimedia broadcast multicast service (MBMS), subscriber and equipment trace, RAN information management (RIM), paging, positioning, and delivery of warning messages. The base stations102may communicate with each other directly or indirectly (e.g., through the EPC/NGC) over backhaul links134, which may be wired or wireless.

The communication links120between the base stations102and the UEs104may include UL (also referred to as reverse link) transmissions from a UE104to a base station102and/or downlink (DL) (also referred to as forward link) transmissions from a base station102to a UE104. The communication links120may use MIMO antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity. The communication links120may be through one or more carrier frequencies. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or less carriers may be allocated for DL than for UL).

Receive beams may be spatially related. A spatial relation means that parameters for a transmit beam for a second reference signal can be derived from information about a receive beam for a first reference signal. For example, a UE may use a particular receive beam to receive a reference downlink reference signal (e.g., synchronization signal block (SSB)) from a base station. The UE can then form a transmit beam for sending an uplink reference signal (e.g., sounding reference signal (SRS)) to that base station based on the parameters of the receive beam.

According to various aspects,FIG.2Aillustrates an example wireless network structure200. For example, an NGC210(also referred to as a “5GC”) can be viewed functionally as control plane functions214(e.g., UE registration, authentication, network access, gateway selection, etc.) and user plane functions212, (e.g., UE gateway function, access to data networks, IP routing, etc.) which operate cooperatively to form the core network. User plane interface (NG-U)213and control plane interface (NG-C)215connect the gNB222to the NGC210and specifically to the control plane functions214and user plane functions212. In an additional configuration, an eNB224may also be connected to the NGC210via NG-C215to the control plane functions214and NG-U213to user plane functions212. Further, eNB224may directly communicate with gNB222via a backhaul connection223. In some configurations, the New RAN220may only have one or more gNBs222, while other configurations include one or more of both eNBs224and gNBs222. Either gNB222or eNB224may communicate with UEs204(e.g., any of the UEs depicted inFIG.1). Another optional aspect may include location server230, which may be in communication with the NGC210to provide location assistance for UEs204. The location server230can be implemented as a plurality of separate servers (e.g., physically separate servers, different software modules on a single server, different software modules spread across multiple physical servers, etc.), or alternately may each correspond to a single server. The location server230can be configured to support one or more location services for UEs204that can connect to the location server230via the core network, NGC210, and/or via the Internet (not illustrated). Further, the location server230may be integrated into a component of the core network, or alternatively may be external to the core network.

According to various aspects,FIG.2Billustrates another example wireless network structure250. For example, an NGC260(also referred to as a “5GC”) can be viewed functionally as control plane functions, provided by an access and mobility management function (AMF)/user plane function (UPF)264, and user plane functions, provided by a session management function (SMF)262, which operate cooperatively to form the core network (i.e., NGC260). User plane interface263and control plane interface265connect the eNB224to the NGC260and specifically to SMF262and AMF/UPF264, respectively. In an additional configuration, a gNB222may also be connected to the NGC260via control plane interface265to AMF/UPF264and user plane interface263to SMF262. Further, eNB224may directly communicate with gNB222via the backhaul connection223, with or without gNB direct connectivity to the NGC260. In some configurations, the New RAN220may only have one or more gNBs222, while other configurations include one or more of both eNBs224and gNBs222. Either gNB222or eNB224may communicate with UEs204(e.g., any of the UEs depicted inFIG.1). The base stations of the New RAN220communicate with the AMF-side of the AMF/UPF264over the N2 interface and the UPF-side of the AMF/UPF264over the N3 interface.

The functions of the AMF include registration management, connection management, reachability management, mobility management, lawful interception, transport for session management (SM) messages between the UE204and the SMF262, transparent proxy services for routing SM messages, access authentication and access authorization, transport for short message service (SMS) messages between the UE204and 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 the UE204, and receives the intermediate key that was established as a result of the UE204authentication process. In the case of authentication based on a UMTS (universal mobile telecommunications system) subscriber identity module (USIM), the AMF retrieves the security material from the AUSF. The functions of the AMF also include security context management (SCM). The SCM receives a key from the SEAF that it uses to derive access-network specific keys. The functionality of the AMF also includes location services management for regulatory services, transport for location services messages between the UE204and the location management function (LMF)270, as well as between the New RAN220and the LMF270, evolved packet system (EPS) bearer identifier allocation for interworking with the EPS, and UE204mobility event notification. In addition, the AMF also supports functionalities for non-3GPP access networks.

Functions of the UPF include acting as an anchor point for intra-/inter-RAT mobility (when applicable), acting as an external protocol data unit (PDU) session point of interconnect to the 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 the DL), UL traffic verification (service data flow (SDF) to QoS flow mapping), transport level packet marking in the UL and DL, DL packet buffering and DL data notification triggering, and sending and forwarding of one or more “end markers” to the source RAN node.

The functions of the SMF262include session management, UE Internet protocol (IP) address allocation and management, selection and control of user plane functions, configuration of traffic steering at the UPF to route traffic to the proper destination, control of part of policy enforcement and QoS, and downlink data notification. The interface over which the SMF262communicates with the AMF-side of the AMF/UPF264is referred to as the N11 interface.

Another optional aspect may include a LMF270, which may be in communication with the NGC260to provide location assistance for UEs204. The LMF270can be implemented as a plurality of separate servers (e.g., physically separate servers, different software modules on a single server, different software modules spread across multiple physical servers, etc.), or alternately may each correspond to a single server. The LMF270can be configured to support one or more location services for UEs204that can connect to the LMF270via the core network, NGC260, and/or via the Internet (not illustrated).

FIGS.3A,3B, and3Cillustrate several sample components (represented by corresponding blocks) that may be incorporated into a UE302(which may correspond to any of the UEs described herein), a base station304(which may correspond to any of the base stations described herein), and a network entity306(which may correspond to or embody any of the network functions described herein, including the location server230and the LMF270) to support the file transmission operations as taught herein. It will be appreciated that these components may be implemented in different types of apparatuses in different implementations (e.g., in an ASIC, in a system-on-chip (SoC), etc.). The illustrated components may also be incorporated into other apparatuses in a communication system. For example, other apparatuses in a system may include components similar to those described to provide similar functionality. Also, a given apparatus may contain one or more of the components. For example, an apparatus may include multiple transceiver components that enable the apparatus to operate on multiple carriers and/or communicate via different technologies.

The UE302and the base station304each include wireless wide area network (WWAN) transceiver310and350, respectively, configured to communicate via one or more wireless communication networks (not shown), such as an NR network, an LTE network, a GSM network, and/or the like. The WWAN transceivers310and350may be connected to one or more antennas316and356, respectively, for communicating with other network nodes, such as other UEs, access points, base stations (e.g., eNBs, gNBs), etc., via at least one designated RAT (e.g., NR, LTE, GSM, etc.) over a wireless communication medium of interest (e.g., some set of time/frequency resources in a particular frequency spectrum). The WWAN transceivers310and350may be variously configured for transmitting and encoding signals318and358(e.g., messages, indications, information, and so on), respectively, and, conversely, for receiving and decoding signals318and358(e.g., messages, indications, information, pilots, and so on), respectively, in accordance with the designated RAT. Specifically, the transceivers310and350include one or more transmitters314and354, respectively, for transmitting and encoding signals318and358, respectively, and one or more receivers312and352, respectively, for receiving and decoding signals318and358, respectively.

The UE302and the base station304also include, at least in some cases, wireless local area network (WLAN) transceivers320and360, respectively. The WLAN transceivers320and360may be connected to one or more antennas326and366, respectively, for communicating with other network nodes, such as other UEs, access points, base stations, etc., via at least one designated RAT (e.g., WiFi, LTE-D, Bluetooth®, etc.) over a wireless communication medium of interest. The WLAN transceivers320and360may be variously configured for transmitting and encoding signals328and368(e.g., messages, indications, information, and so on), respectively, and, conversely, for receiving and decoding signals328and368(e.g., messages, indications, information, pilots, and so on), respectively, in accordance with the designated RAT. Specifically, the transceivers320and360include one or more transmitters324and364, respectively, for transmitting and encoding signals328and368, respectively, and one or more receivers322and362, respectively, for receiving and decoding signals328and368, respectively.

Transceiver circuitry including a transmitter and a receiver may comprise an integrated device (e.g., embodied as a transmitter circuit and a receiver circuit of a single communication device) in some implementations, may comprise a separate transmitter device and a separate receiver device in some implementations, or may be embodied in other ways in other implementations. In an aspect, a transmitter may include or be coupled to a plurality of antennas (e.g., antennas316,336, and376), such as an antenna array, that permits the respective apparatus to perform transmit “beamforming,” as described herein. Similarly, a receiver may include or be coupled to a plurality of antennas (e.g., antennas316,336, and376), such as an antenna array, that permits the respective apparatus to perform receive beamforming, as described herein. In an aspect, the transmitter and receiver may share the same plurality of antennas (e.g., antennas316,336, and376), such that the respective apparatus can only receive or transmit at a given time, not both at the same time. A wireless communication device (e.g., one or both of the transceivers310and320and/or350and360) of the apparatuses302and/or304may also comprise a network listen module (NLM) or the like for performing various measurements.

The apparatuses302and304also include, at least in some cases, satellite positioning systems (SPS) receivers330and370. The SPS receivers330and370may be connected to one or more antennas336and376, respectively, for receiving SPS signals338and378, respectively, such as global positioning system (GPS) signals, global navigation satellite system (GLONASS) signals, Galileo signals, Beidou signals, Indian Regional Navigation Satellite System (NAVIC), Quasi-Zenith Satellite System (QZSS), etc. The SPS receivers330and370may comprise any suitable hardware and/or software for receiving and processing SPS signals338and378, respectively. The SPS receivers330and370request information and operations as appropriate from the other systems, and performs calculations necessary to determine the apparatus'302and304positions using measurements obtained by any suitable SPS algorithm.

The base station304and the network entity306each include at least one network interfaces380and390for communicating with other network entities. For example, the network interfaces380and390(e.g., one or more network access ports) may be configured to communicate with one or more network entities via a wire-based or wireless backhaul connection. In some aspects, the network interfaces380and390may be implemented as transceivers configured to support wire-based or wireless signal communication. This communication may involve, for example, sending and receiving: messages, parameters, or other types of information.

The apparatuses302,304, and306also include other components that may be used in conjunction with the operations as disclosed herein. The UE302includes processor circuitry implementing a processing system332for providing functionality relating to, for example, false base station (FBS) detection as disclosed herein and for providing other processing functionality. The base station304includes a processing system384for providing functionality relating to, for example, FBS detection as disclosed herein and for providing other processing functionality. The network entity306includes a processing system394for providing functionality relating to, for example, FBS detection as disclosed herein and for providing other processing functionality. In an aspect, the processing systems332,384, and394may include, for example, one or more general purpose processors, multi-core processors, ASICs, digital signal processors (DSPs), field programmable gate arrays (FPGA), or other programmable logic devices or processing circuitry.

The apparatuses302,304, and306include memory circuitry implementing memory components340,386, and396(e.g., each including a memory device), respectively, for maintaining information (e.g., information indicative of reserved resources, thresholds, parameters, and so on). In some cases, the apparatuses302,304, and306may include positioning modules342,388and389, respectively. The positioning modules342,388and389may be hardware circuits that are part of or coupled to the processing systems332,384, and394, respectively, that, when executed, cause the apparatuses302,304, and306to perform the functionality described herein. Alternatively, the positioning modules342,388and389may be memory modules (as shown inFIGS.3A-C) stored in the memory components340,386, and396, respectively, that, when executed by the processing systems332,384, and394, cause the apparatuses302,304, and306to perform the functionality described herein.

The UE302may include one or more sensors344coupled to the processing system332to provide movement and/or orientation information that is independent of motion data derived from signals received by the WWAN transceiver310, the WLAN transceiver320, and/or the GPS receiver330. By way of example, the sensor(s)344may include an accelerometer (e.g., a micro-electrical mechanical systems (MEMS) device), a gyroscope, a geomagnetic sensor (e.g., a compass), an altimeter (e.g., a barometric pressure altimeter), and/or any other type of movement detection sensor. Moreover, the sensor(s)344may include a plurality of different types of devices and combine their outputs in order to provide motion information. For example, the sensor(s)344may use a combination of a multi-axis accelerometer and orientation sensors to provide the ability to compute positions in 2D and/or 3D coordinate systems.

In addition, the UE302includes a user interface346for providing indications (e.g., audible and/or visual indications) to a user and/or for receiving user input (e.g., upon user actuation of a sensing device such a keypad, a touch screen, a microphone, and so on). Although not shown, the apparatuses304and306may also include user interfaces.

At the UE302, the receiver312receives a signal through its respective antenna(s)316. The receiver312recovers information modulated onto an RF carrier and provides the information to the processing system332. The transmitter314and the receiver312implement Layer-1 functionality associated with various signal processing functions. The receiver312may perform spatial processing on the information to recover any spatial streams destined for the UE302. If multiple spatial streams are destined for the UE302, they may be combined by the receiver312into a single OFDM symbol stream. The receiver312then converts the OFDM symbol stream from the time-domain to the frequency domain using a fast Fourier transform (FFT). The frequency domain signal comprises a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, and the reference signal, are recovered and demodulated by determining the most likely signal constellation points transmitted by the base station304. These soft decisions may be based on channel estimates computed by a channel estimator. The soft decisions are then decoded and de-interleaved to recover the data and control signals that were originally transmitted by the base station304on the physical channel. The data and control signals are then provided to the processing system332, which implements Layer-3 and Layer-2 functionality.

In the UL, the processing system332provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, and control signal processing to recover IP packets from the core network. The processing system332is also responsible for error detection.

Channel estimates derived by the channel estimator from a reference signal or feedback transmitted by the base station304may be used by the transmitter314to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the transmitter314may be provided to different antenna(s)316. The transmitter314may modulate an RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the base station304in a manner similar to that described in connection with the receiver function at the UE302. The receiver352receives a signal through its respective antenna(s)356. The receiver352recovers information modulated onto an RF carrier and provides the information to the processing system384.

In the UL, the processing system384provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover IP packets from the UE302. IP packets from the processing system384may be provided to the core network. The processing system384is also responsible for error detection.

For convenience, the apparatuses302,304, and/or306are shown inFIGS.3A-Cas including various components that may be configured according to the various examples described herein. It will be appreciated, however, that the illustrated blocks may have different functionality in different designs.

The various components of the apparatuses302,304, and306may communicate with each other over data buses334,382, and392, respectively. The components ofFIGS.3A-Cmay be implemented in various ways. In some implementations, the components ofFIGS.3A-Cmay be implemented in one or more circuits such as, for example, one or more processors and/or one or more ASICs (which may include one or more processors). Here, each circuit may use and/or incorporate at least one memory component for storing information or executable code used by the circuit to provide this functionality. For example, some or all of the functionality represented by blocks310to346may be implemented by processor and memory component(s) of the UE302(e.g., by execution of appropriate code and/or by appropriate configuration of processor components). Similarly, some or all of the functionality represented by blocks350to388may be implemented by processor and memory component(s) of the base station304(e.g., by execution of appropriate code and/or by appropriate configuration of processor components). Also, some or all of the functionality represented by blocks390to396may be implemented by processor and memory component(s) of the network entity306(e.g., by execution of appropriate code and/or by appropriate configuration of processor components). For simplicity, various operations, acts, and/or functions are described herein as being performed “by a UE,” “by a base station,” “by a positioning entity,” etc. However, as will be appreciated, such operations, acts, and/or functions may actually be performed by specific components or combinations of components of the UE, base station, positioning entity, etc., such as the processing systems332,384,394, the transceivers310,320,350, and360, the memory components340,386, and396, the positioning modules342,388and389, etc.

FIG.4Ais a diagram400illustrating an example of a DL frame structure, according to aspects of the disclosure.FIG.4Bis a diagram430illustrating an example of channels within the DL frame structure, according to aspects of the disclosure. Other wireless communications technologies may have a different frame structures and/or different channels.

LTE supports a single numerology (subcarrier spacing, symbol length, etc.). In contrast NR may support multiple numerologies, for example, subcarrier spacing of 15 kHz, 30 kHz, 60 kHz, 120 kHz and 204 kHz or greater may be available. Table 1 provided below lists some various parameters for different NR numerologies.

In the examples ofFIGS.4A and4B, a numerology of 15 kHz is used. Thus, in the time domain, a frame (e.g., 10 ms) is divided into 10 equally sized subframes of 1 ms each, and each subframe includes one time slot. InFIGS.4A and4B, time is represented horizontally (e.g., on the X axis) with time increasing from left to right, while frequency is represented vertically (e.g., on the Y axis) with frequency increasing (or decreasing) from bottom to top.

A resource grid may be used to represent time slots, each time slot including one or more time concurrent resource blocks (RBs) (also referred to as physical RBs (PRBs)) in the frequency domain. The resource grid is further divided into multiple resource elements (REs). An RE may correspond to one symbol length in the time domain and one subcarrier in the frequency domain. In the numerology ofFIGS.4A and4B, for a normal cyclic prefix, an RB may contain 12 consecutive subcarriers in the frequency domain and 7 consecutive symbols (for DL, OFDM symbols; for UL, SC-FDMA symbols) in the time domain, for a total of 84 REs. For an extended cyclic prefix, an RB may contain 12 consecutive subcarriers in the frequency domain and 6 consecutive symbols in the time domain, for a total of 72 REs. The number of bits carried by each RE depends on the modulation scheme.

As illustrated inFIG.4A, some of the REs carry DL reference (pilot) signals (DL-RS) for channel estimation at the UE. The DL-RS may include demodulation reference signals (DMRS) and channel state information reference signals (CSI-RS), exemplary locations of which are labeled “R” inFIG.4A.

FIG.4Billustrates an example of various channels within a DL subframe of a frame. The physical downlink control channel (PDCCH) carries DL control information (DCI) within one or more control channel elements (CCEs), each CCE including nine RE groups (REGs), each REG including four consecutive REs in an OFDM symbol. The DCI carries information about UL resource allocation (persistent and non-persistent) and descriptions about DL data transmitted to the UE. Multiple (e.g., up to 8) DCIs can be configured in the PDCCH, and these DCIs can have one of multiple formats. For example, there are different DCI formats for UL scheduling, for non-MIMO DL scheduling, for MIMO DL scheduling, and for UL power control.

A primary synchronization signal (PSS) is used by a UE to determine subframe/symbol timing and a physical layer identity. A secondary synchronization signal (SSS) is used by a UE to determine a physical layer cell identity group number and radio frame timing. Based on the physical layer identity and the physical layer cell identity group number, the UE can determine a PCI. Based on the PCI, the UE can determine the locations of the aforementioned DL-RS. The physical broadcast channel (PBCH), which carries an MIB, may be logically grouped with the PSS and SSS to form an SSB (also referred to as an SS/PBCH). The MIB provides a number of RBs in the DL system bandwidth and a system frame number (SFN). The physical downlink shared channel (PDSCH) carries user data, broadcast system information not transmitted through the PBCH such as system information blocks (SIBs), and paging messages.

In some cases, the DL RS illustrated inFIG.4Amay be positioning reference signals (PRS).FIG.5illustrates an exemplary PRS configuration500for a cell supported by a wireless node (such as a base station102).FIG.5shows how PRS positioning occasions are determined by a system frame number (SFN), a cell specific subframe offset (APRs)552, and the PRS periodicity (TPRS)520. Typically, the cell specific PRS subframe configuration is defined by a “PRS Configuration Index” IPRSincluded in observed time difference of arrival (OTDOA) assistance data. The PRS periodicity (TPRS)520and the cell specific subframe offset (ΔPRS) are defined based on the PRS configuration index/pRs, as illustrated in Table 2 below.

A PRS configuration is defined with reference to the SFN of a cell that transmits PRS. PRS instances, for the first subframe of the NPRSdownlink subframes comprising a first PRS positioning occasion, may satisfy:
(10×nf+└ns/2┘−ΔPRS)modTPRS=0,
where nfis the SFN with 0≤nf≤1023, nsis the slot number within the radio frame defined by nfwith 0≤ns≤19, TPRSis the PRS periodicity520, and ΔPRSis the cell-specific subframe offset552.

As shown inFIG.5, the cell specific subframe offset ΔPRS552may be defined in terms of the number of subframes transmitted starting from system frame number 0 (Slot ‘Number 0’, marked as slot550) to the start of the first (subsequent) PRS positioning occasion. In the example inFIG.5, the number of consecutive positioning subframes (NPRS) in each of the consecutive PRS positioning occasions518a,518b, and518cequals 4. That is, each shaded block representing PRS positioning occasions518a,518b, and518crepresents four subframes.

In some aspects, when a UE receives a PRS configuration index IPRSin the OTDOA assistance data for a particular cell, the UE may determine the PRS periodicity TPRS520and PRS subframe offset ΔPRSusing Table 2. The UE may then determine the radio frame, subframe, and slot when a PRS is scheduled in the cell (e.g., using equation (1)). The OTDOA assistance data may be determined by, for example, the location server (e.g., location server230, LMF270), and includes assistance data for a reference cell, and a number of neighbor cells supported by various base stations.

Typically, PRS occasions from all cells in a network that use the same frequency are aligned in time and may have a fixed known time offset (e.g., cell-specific subframe offset552) relative to other cells in the network that use a different frequency. In SFN-synchronous networks, all wireless nodes (e.g., base stations102) may be aligned on both frame boundary and system frame number. Therefore, in SFN-synchronous networks, all cells supported by the various wireless nodes may use the same PRS configuration index for any particular frequency of PRS transmission. On the other hand, in SFN-asynchronous networks, the various wireless nodes may be aligned on a frame boundary, but not system frame number. Thus, in SFN-asynchronous networks the PRS configuration index for each cell may be configured separately by the network so that PRS occasions align in time.

A UE may determine the timing of the PRS occasions of the reference and neighbor cells for OTDOA positioning, if the UE can obtain the cell timing (e.g., SFN) of at least one of the cells, e.g., the reference cell or a serving cell. The timing of the other cells may then be derived by the UE based, for example, on the assumption that PRS occasions from different cells overlap.

A collection of resource elements that are used for transmission of PRS is referred to as a “PRS resource.” The collection of resource elements can span multiple PRBs in the frequency domain and N (e.g., 1 or more) consecutive symbol(s) within a slot in the time domain. In a given OFDM symbol, a PRS resource occupies consecutive PRBs. A PRS resource is described by at least the following parameters: PRS resource identifier (ID), sequence ID, comb size-N, resource element offset in the frequency domain, starting slot and starting symbol, number of symbols per PRS resource (i.e., the duration of the PRS resource), and QCL information (e.g., QCL with other DL reference signals). In some designs, one antenna port is supported. The comb size indicates the number of subcarriers in each symbol carrying PRS. For example, a comb-size of comb-4 means that every fourth subcarrier of a given symbol carries PRS.

A “PRS resource set” is a set of PRS resources used for the transmission of PRS signals, where each PRS resource has a PRS resource ID. In addition, the PRS resources in a PRS resource set are associated with the same transmission-reception point (TRP). A PRS resource ID in a PRS resource set is associated with a single beam transmitted from a single TRP (where a TRP may transmit one or more beams). That is, each PRS resource of a PRS resource set may be transmitted on a different beam, and as such, a “PRS resource” can also be referred to as a “beam.” Note that this does not have any implications on whether the TRPs and the beams on which PRS are transmitted are known to the UE. A “PRS occasion” is one instance of a periodically repeated time window (e.g., a group of one or more consecutive slots) where PRS are expected to be transmitted. A PRS occasion may also be referred to as a “PRS positioning occasion,” a “positioning occasion,” or simply an “occasion.”

Note that the terms “positioning reference signal” and “PRS” may sometimes refer to specific reference signals that are used for positioning in LTE or NR systems. However, as used herein, unless otherwise indicated, the terms “positioning reference signal” and “PRS” refer to any type of reference signal that can be used for positioning, such as but not limited to, PRS signals in LTE or NR, navigation reference signals (NRSs) in 5G, transmitter reference signals (TRSs), cell-specific reference signals (CRSs), channel state information reference signals (CSI-RSs), primary synchronization signals (PSSs), secondary synchronization signals (SSSs), SSB, etc.

An SRS is an uplink-only signal that a UE transmits to help the base station obtain the channel state information (CSI) for each user. Channel state information describes how an RF signal propagates from the UE to the base station and represents the combined effect of scattering, fading, and power decay with distance. The system uses the SRS for resource scheduling, link adaptation, massive MIMO, beam management, etc.

Several enhancements over the previous definition of SRS have been proposed for SRS for positioning (SRS-P), such as a new staggered pattern within an SRS resource, a new comb type for SRS, new sequences for SRS, a higher number of SRS resource sets per component carrier, and a higher number of SRS resources per component carrier. In addition, the parameters “SpatialRelationInfo” and “PathLossReference” are to be configured based on a DL RS from a neighboring TRP. Further still, one SRS resource may be transmitted outside the active bandwidth part (BWP), and one SRS resource may span across multiple component carriers. Lastly, the UE may transmit through the same transmit beam from multiple SRS resources for UL-AoA. All of these are features that are additional to the current SRS framework, which is configured through RRC higher layer signaling (and potentially triggered or activated through MAC control element (CE) or downlink control information (DCI)).

As noted above, SRSs in NR are UE-specifically configured reference signals transmitted by the UE used for the purposes of the sounding the uplink radio channel. Similar to CSI-RS, such sounding provides various levels of knowledge of the radio channel characteristics. On one extreme, the SRS can be used at the gNB simply to obtain signal strength measurements, e.g., for the purposes of UL beam management. On the other extreme, SRS can be used at the gNB to obtain detailed amplitude and phase estimates as a function of frequency, time and space. In NR, channel sounding with SRS supports a more diverse set of use cases compared to LTE (e.g., downlink CSI acquisition for reciprocity-based gNB transmit beamforming (downlink MIMO); uplink CSI acquisition for link adaptation and codebook/non-codebook based precoding for uplink MIMO, uplink beam management, etc.).

The SRS can be configured using various options. The time/frequency mapping of an SRS resource is defined by the following characteristics.Time duration NsymbSRS—The time duration of an SRS resource can be 1, 2, or 4 consecutive OFDM symbols within a slot, in contrast to LTE which allows only a single OFDM symbol per slot.Starting symbol location l0—The starting symbol of an SRS resource can be located anywhere within the last 6 OFDM symbols of a slot provided the resource does not cross the end-of-slot boundary.Repetition factor R—For an SRS resource configured with frequency hopping, repetition allows the same set of subcarriers to be sounded in R consecutive OFDM symbols before the next hop occurs (as used herein, a “hop” refers to specifically to a frequency hop). For example, values of R are 1, 2, 4 where R≤NsymbSRS.Transmission comb spacing KTCand comb offset kTC—An SRS resource may occupy resource elements (REs) of a frequency domain comb structure, where the comb spacing is either 2 or 4 REs like in LTE. Such a structure allows frequency domain multiplexing of different SRS resources of the same or different users on different combs, where the different combs are offset from each other by an integer number of REs. The comb offset is defined with respect to a PRB boundary, and can take values in the range 0, 1, . . . , KTC−1 REs. Thus, for comb spacing KTC=2, there are 2 different combs available for multiplexing if needed, and for comb spacing KTC=4, there are 4 different available combs.Periodicity and slot offset for the case of periodic/semi-persistent SRS.Sounding bandwidth within a bandwidth part.

For low latency positioning, a gNB may trigger a UL SRS-P via a DCI (e.g., transmitted SRS-P may include repetition or beam-sweeping to enable several gNBs to receive the SRS-P). Alternatively, the gNB may send information regarding aperiodic PRS transmission to the UE (e.g., this configuration may include information about PRS from multiple gNBs to enable the UE to perform timing computations for positioning (UE-based) or for reporting (UE-assisted). While various embodiments of the present disclosure relate to DL PRS-based positioning procedures, some or all of such embodiments may also apply to UL SRS-P-based positioning procedures.

Note that the terms “sounding reference signal”, “SRS” and “SRS-P” may sometimes refer to specific reference signals that are used for positioning in LTE or NR systems. However, as used herein, unless otherwise indicated, the terms “sounding reference signal”, “SRS” and “SRS-P” refer to any type of reference signal that can be used for positioning, such as but not limited to, SRS signals in LTE or NR, navigation reference signals (NRSs) in 5G, transmitter reference signals (TRSs), random access channel (RACH) signals for positioning (e.g., RACH preambles, such as Msg-1 in 4-Step RACH procedure or Msg-A in 2-Step RACH procedure), etc.

3GPP Rel. 16 introduced various NR positioning aspects directed to increase location accuracy of positioning schemes that involve measurement(s) associated with one or more UL or DL PRSs (e.g., higher bandwidth (BW), FR2 beam-sweeping, angle-based measurements such as Angle of Arrival (AoA) and Angle of Departure (AoD) measurements, multi-cell Round-Trip Time (RTT) measurements, etc.). If latency reduction is a priority, then UE-based positioning techniques (e.g., DL-only techniques without UL location measurement reporting) are typically used. However, if latency is less of a concern, then UE-assisted positioning techniques can be used, whereby UE-measured data is reported to a network entity (e.g., location server230, LMF270, etc.). Latency associated UE-assisted positioning techniques can be reduced somewhat by implementing the LMF in the RAN.

Layer-3 (L3) signaling (e.g., RRC or Location Positioning Protocol (LPP)) is typically used to transport reports that comprise location-based data in association with UE-assisted positioning techniques. L3 signaling is associated with relatively high latency (e.g., above 100 ms) compared with Layer-1 (L1, or PHY layer) signaling or Layer-2 (L2, or MAC layer) signaling. In some cases, lower latency (e.g., less than 100 ms, less than 10 ms, etc.) between the UE and the RAN for location-based reporting may be desired. In such cases, L3 signaling may not be capable of reaching these lower latency levels. L3 signaling of positioning measurements may comprise any combination of the following:One or multiple TOA, TDOA, RSRP or Rx-Tx measurements,One or multiple AoA/AoD (e.g., currently agreed only for gNB->LMF reporting DL AoA and UL AoD) measurements,One or multiple Multipath reporting measurements, e.g., per-path ToA, RSRP, AoA/AoD (e.g., currently only per-path ToA allowed in LTE)One or multiple motion states (e.g., walking, driving, etc.) and trajectories (e.g., currently for UE), and/orOne or multiple report quality indications.

More recently, L1 and L2 signaling has been contemplated for use in association with PRS-based reporting. For example, L1 and L2 signaling is currently used in some systems to transport CSI reports (e.g., reporting of Channel Quality Indications (CQIs), Precoding Matrix Indicators (PMIs), Layer Indicators (Lis), L1-RSRP, etc.). CSI reports may comprise a set of fields in a pre-defined order (e.g., defined by the relevant standard). A single UL transmission (e.g., on PUSCH or PUCCH) may include multiple reports, referred to herein as ‘sub-reports’, which are arranged according to a pre-defined priority (e.g., defined by the relevant standard). In some designs, the pre-defined order may be based on an associated sub-report periodicity (e.g., aperiodic/semi-persistent/periodic (A/SP/P) over PUSCH/PUCCH), measurement type (e.g., L1-RSRP or not), serving cell index (e.g., in carrier aggregation (CA) case), and reportconfigID. With 2-part CSI reporting, the part 1s of all reports are grouped together, and the part 2s are grouped separately, and each group is separately encoded (e.g., part 1 payload size is fixed based on configuration parameters, while part 2 size is variable and depends on configuration parameters and also on associated part 1 content). A number of coded bits/symbols to be output after encoding and rate-matching is computed based on a number of input bits and beta factors, per the relevant standard. Linkages (e.g., time offsets) are defined between instances of RSs being measured and corresponding reporting. In some designs, CSI-like reporting of PRS-based measurement data using L1 and L2 signaling may be implemented.

FIG.6illustrates an exemplary wireless communications system600according to various aspects of the disclosure. In the example ofFIG.6, a UE604, which may correspond to any of the UEs described above with respect toFIG.1(e.g., UEs104, UE182, UE190, etc.), is attempting to calculate an estimate of its position, or assist another entity (e.g., a base station or core network component, another UE, a location server, a third party application, etc.) to calculate an estimate of its position. The UE604may communicate wirelessly with a plurality of base stations602a-d(collectively, base stations602), which may correspond to any combination of base stations102or180and/or WLAN AP150inFIG.1, using RF signals and standardized protocols for the modulation of the RF signals and the exchange of information packets. By extracting different types of information from the exchanged RF signals, and utilizing the layout of the wireless communications system600(i.e., the base stations locations, geometry, etc.), the UE604may determine its position, or assist in the determination of its position, in a predefined reference coordinate system. In an aspect, the UE604may specify its position using a two-dimensional coordinate system; however, the aspects disclosed herein are not so limited, and may also be applicable to determining positions using a three-dimensional coordinate system, if the extra dimension is desired. Additionally, whileFIG.6illustrates one UE604and four base stations602, as will be appreciated, there may be more UEs604and more or fewer base stations602.

To support position estimates, the base stations602may be configured to broadcast reference RF signals (e.g., Positioning Reference Signals (PRS), Cell-specific Reference Signals (CRS), Channel State Information Reference Signals (CSI-RS), synchronization signals, etc.) to UEs604in their coverage areas to enable a UE604to measure reference RF signal timing differences (e.g., OTDOA or reference signal time difference (RSTD)) between pairs of network nodes and/or to identify the beam that best excite the LOS or shortest radio path between the UE604and the transmitting base stations602. Identifying the LOS/shortest path beam(s) is of interest not only because these beams can subsequently be used for OTDOA measurements between a pair of base stations602, but also because identifying these beams can directly provide some positioning information based on the beam direction. Moreover, these beams can subsequently be used for other position estimation methods that require precise ToA, such as round-trip time estimation based methods.

As used herein, a “network node” may be a base station602, a cell of a base station602, a remote radio head, an antenna of a base station602, where the locations of the antennas of a base station602are distinct from the location of the base station602itself, or any other network entity capable of transmitting reference signals. Further, as used herein, a “node” may refer to either a network node or a UE.

A location server (e.g., location server230) may send assistance data to the UE604that includes an identification of one or more neighbor cells of base stations602and configuration information for reference RF signals transmitted by each neighbor cell. Alternatively, the assistance data can originate directly from the base stations602themselves (e.g., in periodically broadcasted overhead messages, etc.). Alternatively, the UE604can detect neighbor cells of base stations602itself without the use of assistance data. The UE604(e.g., based in part on the assistance data, if provided) can measure and (optionally) report the OTDOA from individual network nodes and/or RSTDs between reference RF signals received from pairs of network nodes. Using these measurements and the known locations of the measured network nodes (i.e., the base station(s)602or antenna(s) that transmitted the reference RF signals that the UE604measured), the UE604or the location server can determine the distance between the UE604and the measured network nodes and thereby calculate the location of the UE604.

The term “position estimate” is used herein to refer to an estimate of a position for a UE604, which may be geographic (e.g., may comprise a latitude, longitude, and possibly altitude) or civic (e.g., may comprise a street address, building designation, or precise point or area within or nearby to a building or street address, such as a particular entrance to a building, a particular room or suite in a building, or a landmark such as a town square). A position estimate may also be referred to as a “location,” a “position,” a “fix,” a “position fix,” a “location fix,” a “location estimate,” a “fix estimate,” or by some other term. The means of obtaining a location estimate may be referred to generically as “positioning,” “locating,” or “position fixing.” A particular solution for obtaining a position estimate may be referred to as a “position solution.” A particular method for obtaining a position estimate as part of a position solution may be referred to as a “position method” or as a “positioning method.”

The term “base station” may refer to a single physical transmission point or to multiple physical transmission points that may or may not be co-located. For example, where the term “base station” refers to a single physical transmission point, the physical transmission point may be an antenna of the base station (e.g., base station602) corresponding to a cell of the base station. Where the term “base station” refers to multiple co-located physical transmission points, the physical transmission points may be an array of antennas (e.g., as in a MIMO system or where the base station employs beamforming) of the base station. Where the term “base station” refers to multiple non-co-located physical transmission points, the physical transmission points may be a Distributed Antenna System (DAS) (a network of spatially separated antennas connected to a common source via a transport medium) or a Remote Radio Head (RRH) (a remote base station connected to a serving base station). Alternatively, the non-co-located physical transmission points may be the serving base station receiving the measurement report from the UE (e.g., UE604) and a neighbor base station whose reference RF signals the UE is measuring. Thus,FIG.6illustrates an aspect in which base stations602aand602bform a DAS/RRH620. For example, the base station602amay be the serving base station of the UE604and the base station602bmay be a neighbor base station of the UE604. As such, the base station602bmay be the RRH of the base station602a. The base stations602aand602bmay communicate with each other over a wired or wireless link622.

To accurately determine the position of the UE604using the OTDOAs and/or RSTDs between RF signals received from pairs of network nodes, the UE604needs to measure the reference RF signals received over the LOS path (or the shortest NLOS path where an LOS path is not available), between the UE604and a network node (e.g., base station602, antenna). However, RF signals travel not only by the LOS/shortest path between the transmitter and receiver, but also over a number of other paths as the RF signals spread out from the transmitter and reflect off other objects such as hills, buildings, water, and the like on their way to the receiver. Thus,FIG.6illustrates a number of LOS paths610and a number of NLOS paths612between the base stations602and the UE604. Specifically,FIG.6illustrates base station602atransmitting over an LOS path610aand an NLOS path612a, base station602btransmitting over an LOS path610band two NLOS paths612b, base station602ctransmitting over an LOS path610cand an NLOS path612c, and base station602dtransmitting over two NLOS paths612d. As illustrated inFIG.6, each NLOS path612reflects off some object630(e.g., a building). As will be appreciated, each LOS path610and NLOS path612transmitted by a base station602may be transmitted by different antennas of the base station602(e.g., as in a MIMO system), or may be transmitted by the same antenna of a base station602(thereby illustrating the propagation of an RF signal). Further, as used herein, the term “LOS path” refers to the shortest path between a transmitter and receiver, and may not be an actual LOS path, but rather, the shortest NLOS path.

In an aspect, one or more of base stations602may be configured to use beamforming to transmit RF signals. In that case, some of the available beams may focus the transmitted RF signal along the LOS paths610(e.g., the beams produce highest antenna gain along the LOS paths) while other available beams may focus the transmitted RF signal along the NLOS paths612. A beam that has high gain along a certain path and thus focuses the RF signal along that path may still have some RF signal propagating along other paths; the strength of that RF signal naturally depends on the beam gain along those other paths. An “RF signal” comprises an electromagnetic wave that transports information through the space between the transmitter and the receiver. As used herein, a transmitter may transmit a single “RF signal” or multiple “RF signals” to a receiver. However, as described further below, the receiver may receive multiple “RF signals” corresponding to each transmitted RF signal due to the propagation characteristics of RF signals through multipath channels.

Where a base station602uses beamforming to transmit RF signals, the beams of interest for data communication between the base station602and the UE604will be the beams carrying RF signals that arrive at UE604with the highest signal strength (as indicated by, e.g., the Received Signal Received Power (RSRP) or SINR in the presence of a directional interfering signal), whereas the beams of interest for position estimation will be the beams carrying RF signals that excite the shortest path or LOS path (e.g., an LOS path610). In some frequency bands and for antenna systems typically used, these will be the same beams. However, in other frequency bands, such as mmW, where typically a large number of antenna elements can be used to create narrow transmit beams, they may not be the same beams. As described below with reference toFIG.7, in some cases, the signal strength of RF signals on the LOS path610may be weaker (e.g., due to obstructions) than the signal strength of RF signals on an NLOS path612, over which the RF signals arrive later due to propagation delay.

FIG.7illustrates an exemplary wireless communications system700according to various aspects of the disclosure. In the example ofFIG.7, a UE704, which may correspond to UE604inFIG.6, is attempting to calculate an estimate of its position, or to assist another entity (e.g., a base station or core network component, another UE, a location server, a third party application, etc.) to calculate an estimate of its position. The UE704may communicate wirelessly with a base station702, which may correspond to one of base stations602inFIG.6, using RF signals and standardized protocols for the modulation of the RF signals and the exchange of information packets.

As illustrated inFIG.7, the base station702is utilizing beamforming to transmit a plurality of beams711-715of RF signals. Each beam711-715may be formed and transmitted by an array of antennas of the base station702. AlthoughFIG.7illustrates a base station702transmitting five beams711-715, as will be appreciated, there may be more or fewer than five beams, beam shapes such as peak gain, width, and side-lobe gains may differ amongst the transmitted beams, and some of the beams may be transmitted by a different base station.

A beam index may be assigned to each of the plurality of beams711-715for purposes of distinguishing RF signals associated with one beam from RF signals associated with another beam. Moreover, the RF signals associated with a particular beam of the plurality of beams711-715may carry a beam index indicator. A beam index may also be derived from the time of transmission, e.g., frame, slot and/or OFDM symbol number, of the RF signal. The beam index indicator may be, for example, a three-bit field for uniquely distinguishing up to eight beams. If two different RF signals having different beam indices are received, this would indicate that the RF signals were transmitted using different beams. If two different RF signals share a common beam index, this would indicate that the different RF signals are transmitted using the same beam. Another way to describe that two RF signals are transmitted using the same beam is to say that the antenna port(s) used for the transmission of the first RF signal are spatially quasi-collocated with the antenna port(s) used for the transmission of the second RF signal.

In the example ofFIG.7, the UE704receives an NLOS data stream723of RF signals transmitted on beam713and an LOS data stream724of RF signals transmitted on beam714. AlthoughFIG.7illustrates the NLOS data stream723and the LOS data stream724as single lines (dashed and solid, respectively), as will be appreciated, the NLOS data stream723and the LOS data stream724may each comprise multiple rays (i.e., a “cluster”) by the time they reach the UE704due, for example, to the propagation characteristics of RF signals through multipath channels. For example, a cluster of RF signals is formed when an electromagnetic wave is reflected off of multiple surfaces of an object, and reflections arrive at the receiver (e.g., UE704) from roughly the same angle, each travelling a few wavelengths (e.g., centimeters) more or less than others. A “cluster” of received RF signals generally corresponds to a single transmitted RF signal.

In the example ofFIG.7, the NLOS data stream723is not originally directed at the UE704, although, as will be appreciated, it could be, as are the RF signals on the NLOS paths612inFIG.6. However, it is reflected off a reflector740(e.g., a building) and reaches the UE704without obstruction, and therefore, may still be a relatively strong RF signal. In contrast, the LOS data stream724is directed at the UE704but passes through an obstruction730(e.g., vegetation, a building, a hill, a disruptive environment such as clouds or smoke, etc.), which may significantly degrade the RF signal. As will be appreciated, although the LOS data stream724is weaker than the NLOS data stream723, the LOS data stream724will arrive at the UE704before the NLOS data stream723because it follows a shorter path from the base station702to the UE704.

As noted above, the beam of interest for data communication between a base station (e.g., base station702) and a UE (e.g., UE704) is the beam carrying RF signals that arrives at the UE with the highest signal strength (e.g., highest RSRP or SINR), whereas the beam of interest for position estimation is the beam carrying RF signals that excite the LOS path and that has the highest gain along the LOS path amongst all other beams (e.g., beam714). That is, even if beam713(the NLOS beam) were to weakly excite the LOS path (due to the propagation characteristics of RF signals, even though not being focused along the LOS path), that weak signal, if any, of the LOS path of beam713may not be as reliably detectable (compared to that from beam714), thus leading to greater error in performing a positioning measurement.

While the beam of interest for data communication and the beam of interest for position estimation may be the same beams for some frequency bands, for other frequency bands, such as mmW, they may not be the same beams. As such, referring toFIG.7, where the UE704is engaged in a data communication session with the base station702(e.g., where the base station702is the serving base station for the UE704) and not simply attempting to measure reference RF signals transmitted by the base station702, the beam of interest for the data communication session may be the beam713, as it is carrying the unobstructed NLOS data stream723. The beam of interest for position estimation, however, would be the beam714, as it carries the strongest LOS data stream724, despite being obstructed.

FIG.8Ais a graph800A showing the RF channel response at a receiver (e.g., UE704) over time according to aspects of the disclosure. Under the channel illustrated inFIG.8A, the receiver receives a first cluster of two RF signals on channel taps at time T1, a second cluster of five RF signals on channel taps at time T2, a third cluster of five RF signals on channel taps at time T3, and a fourth cluster of four RF signals on channel taps at time T4. In the example ofFIG.8A, because the first cluster of RF signals at time T1 arrives first, it is presumed to be the LOS data stream (i.e., the data stream arriving over the LOS or the shortest path), and may correspond to the LOS data stream724. The third cluster at time T3 is comprised of the strongest RF signals, and may correspond to the NLOS data stream723. Seen from the transmitter's side, each cluster of received RF signals may comprise the portion of an RF signal transmitted at a different angle, and thus each cluster may be said to have a different angle of departure (AoD) from the transmitter.FIG.8Bis a diagram800B illustrating this separation of clusters in AoD. The RF signal transmitted in AoD range802amay correspond to one cluster (e.g., “Cluster1”) inFIG.8A, and the RF signal transmitted in AoD range802bmay correspond to a different cluster (e.g., “Cluster3”) inFIG.8A. Note that although AoD ranges of the two clusters depicted inFIG.8Bare spatially isolated, AoD ranges of some clusters may also partially overlap even though the clusters are separated in time. For example, this may arise when two separate buildings at same AoD from the transmitter reflect the signal towards the receiver. Note that althoughFIG.8Aillustrates clusters of two to five channel taps (or “peaks”), as will be appreciated, the clusters may have more or fewer than the illustrated number of channel taps.

RAN1 NR may define UE measurements on DL reference signals (e.g., for serving, reference, and/or neighboring cells) applicable for NR positioning, including DL reference signal time difference (RSTD) measurements for NR positioning, DL RSRP measurements for NR positioning, and UE Rx-Tx (e.g., a hardware group delay from signal reception at UE receiver to response signal transmission at UE transmitter, e.g., for time difference measurements for NR positioning, such as RTT).

RAN1 NR may define gNB measurements based on UL reference signals applicable for NR positioning, such as relative UL time of arrival (RTOA) for NR positioning, UL AoA measurements (e.g., including Azimuth and Zenith Angles) for NR positioning, UL RSRP measurements for NR positioning, and gNB Rx-Tx (e.g., a hardware group delay from signal reception at gNB receiver to response signal transmission at gNB transmitter, e.g., for time difference measurements for NR positioning, such as RTT).

FIG.9is a diagram900showing exemplary timings of RTT measurement signals exchanged between a base station902(e.g., any of the base stations described herein) and a UE904(e.g., any of the UEs described herein), according to aspects of the disclosure. In the example ofFIG.9, the base station902sends an RTT measurement signal910(e.g., PRS, NRS, CRS, CSI-RS, etc.) to the UE904at time t1. The RTT measurement signal910has some propagation delay TPropas it travels from the base station902to the UE904. At time t2(the ToA of the RTT measurement signal910at the UE904), the UE904receives/measures the RTT measurement signal910. After some UE processing time, the UE904transmits an RTT response signal920at time t3. After the propagation delay TProp, the base station902receives/measures the RTT response signal920from the UE904at time t4(the ToA of the RTT response signal920at the base station902).

In order to identify the ToA (e.g., t2) of a reference signal (e.g., an RTT measurement signal910) transmitted by a given network node (e.g., base station902), the receiver (e.g., UE904) first jointly processes all the resource elements (REs) on the channel on which the transmitter is transmitting the reference signal, and performs an inverse Fourier transform to convert the received reference signals to the time domain. The conversion of the received reference signals to the time domain is referred to as estimation of the channel energy response (CER). The CER shows the peaks on the channel over time, and the earliest “significant” peak should therefore correspond to the ToA of the reference signal. Generally, the receiver will use a noise-related quality threshold to filter out spurious local peaks, thereby presumably correctly identifying significant peaks on the channel. For example, the receiver may choose a ToA estimate that is the earliest local maximum of the CER that is at least X dB higher than the median of the CER and a maximum Y dB lower than the main peak on the channel. The receiver determines the CER for each reference signal from each transmitter in order to determine the ToA of each reference signal from the different transmitters.

In some designs, the RTT response signal920may explicitly include the difference between time t3and time t2(i.e., TRx→Tx912). Using this measurement and the difference between time t4and time t1(i.e., TTx→Rx922), the base station902(or other positioning entity, such as location server230, LMF270) can calculate the distance to the UE904as:

d=12⁢c⁢(TT⁢x→R⁢x-TR⁢x→T⁢x)=12⁢c⁢(t2-t1)-12⁢c⁢(t4-t3)
where c is the speed of light. While not illustrated expressly inFIG.9, an additional source of delay or error may be due to UE and gNB hardware group delay for position location.

Various parameters associated with positioning can impact power consumption at the UE. Knowledge of such parameters can be used to estimate (or model) the UE power consumption. By accurately modeling the power consumption of the UE, various power saving features and/or performance enhancing features can be utilized in a predictive manner so as to improve the user experience.

An additional source of delay or error is due to UE and gNB hardware group delay for position location.FIG.10illustrates a diagram1000showing exemplary timings of RTT measurement signals exchanged between a base station (gNB) (e.g., any of the base stations described herein) and a UE (e.g., any of the UEs described herein), according to aspects of the disclosure.FIG.10is similar in some respects toFIG.9. However, inFIG.10, the UE and gNB hardware group delay (which is primarily due to internal hardware delays between a baseband (BB) component and antenna (ANT) at the UE and gNB) is shown with respect1002-1008. As will be appreciated, both Tx-side and Rx-side path-specific or beam-specific delays impact the RTT measurement. Hardware group delays such as1002-1008can contribute to timing errors and/or calibration errors that can impact RTT as well as other measurements such as TDOA, RSTD, and so on, which in turn can impact positioning performance. For example, in some designs, 10 nsec of error will introduce the 3 meter of error in the final fix.

FIG.11illustrates an exemplary wireless communications system1100according to aspects of the disclosure. In the example ofFIG.11, a UE1104(which may correspond to any of the UEs described herein) is attempting to calculate an estimate of its position, or assist another entity (e.g., a base station or core network component, another UE, a location server, a third party application, etc.) to calculate an estimate of its position, via a multi-RTT positioning scheme. The UE1104may communicate wirelessly with a plurality of base stations1102-1,1102-2, and1102-3(collectively, base stations1102, and which may correspond to any of the base stations described herein) using RF signals and standardized protocols for the modulation of the RF signals and the exchange of information packets. By extracting different types of information from the exchanged RF signals, and utilizing the layout of the wireless communications system1100(i.e., the base stations' locations, geometry, etc.), the UE1104may determine its position, or assist in the determination of its position, in a predefined reference coordinate system. In an aspect, the UE1104may specify its position using a two-dimensional coordinate system; however, the aspects disclosed herein are not so limited, and may also be applicable to determining positions using a three-dimensional coordinate system, if the extra dimension is desired. Additionally, whileFIG.11illustrates one UE1104and three base stations1102, as will be appreciated, there may be more UEs1104and more base stations1102.

To support position estimates, the base stations1102may be configured to broadcast reference RF signals (e.g., PRS, NRS, CRS, TRS, CSI-RS, PSS, SSS, etc.) to UEs1104in their coverage area to enable a UE1104to measure characteristics of such reference RF signals. For example, the UE1104may measure the ToA of specific reference RF signals (e.g., PRS, NRS, CRS, CSI-RS, etc.) transmitted by at least three different base stations1102and may use the RTT positioning method to report these ToAs (and additional information) back to the serving base station1102or another positioning entity (e.g., location server230, LMF270).

In an aspect, although described as the UE1104measuring reference RF signals from a base station1102, the UE1104may measure reference RF signals from one of multiple cells supported by a base station1102. Where the UE1104measures reference RF signals transmitted by a cell supported by a base station1102, the at least two other reference RF signals measured by the UE1104to perform the RTT procedure would be from cells supported by base stations1102different from the first base station1102and may have good or poor signal strength at the UE1104.

In order to determine the position (x, y) of the UE1104, the entity determining the position of the UE1104needs to know the locations of the base stations1102, which may be represented in a reference coordinate system as (xk, yk), where k=1, 2, 3 in the example ofFIG.11. Where one of the base stations1102(e.g., the serving base station) or the UE1104determines the position of the UE1104, the locations of the involved base stations1102may be provided to the serving base station1102or the UE1104by a location server with knowledge of the network geometry (e.g., location server230, LMF270). Alternatively, the location server may determine the position of the UE1104using the known network geometry.

Either the UE1104or the respective base station1102may determine the distance (dk, where k=1, 2, 3) between the UE1104and the respective base station1102. In an aspect, determining the RTT1110of signals exchanged between the UE1104and any base station1102can be performed and converted to a distance (dk). As discussed further below, RTT techniques can measure the time between sending a signaling message (e.g., reference RF signals) and receiving a response. These methods may utilize calibration to remove any processing delays. In some environments, it may be assumed that the processing delays for the UE1104and the base stations1102are the same. However, such an assumption may not be true in practice.

Once each distance dkis determined, the UE1104, a base station1102, or the location server (e.g., location server230, LMF270) can solve for the position (x, y) of the UE1104by using a variety of known geometric techniques, such as, for example, trilateration. FromFIG.11, it can be seen that the position of the UE1104ideally lies at the common intersection of three semicircles, each semicircle being defined by radius dkand center (xk, yk), where k=1, 2, 3.

In some instances, additional information may be obtained in the form of an angle of arrival (AoA) or angle of departure (AoD) that defines a straight line direction (e.g., which may be in a horizontal plane or in three dimensions) or possibly a range of directions (e.g., for the UE1104from the location of a base station1102). The intersection of the two directions at or near the point (x, y) can provide another estimate of the location for the UE1104.

A position estimate (e.g., for a UE1104) may be referred to by other names, such as a location estimate, location, position, position fix, fix, or the like. A position estimate may be geodetic and comprise coordinates (e.g., latitude, longitude, and possibly altitude) or may be civic and comprise a street address, postal address, or some other verbal description of a location. A position estimate may further be defined relative to some other known location or defined in absolute terms (e.g., using latitude, longitude, and possibly altitude). A position estimate may include an expected error or uncertainty (e.g., by including an area or volume within which the location is expected to be included with some specified or default level of confidence).

FIG.12illustrates is a diagram1200showing exemplary timings of RTT measurement signals exchanged between a base station (e.g., any of the base stations described herein) and a UE (e.g., any of the UEs described herein), according to other aspects of the disclosure. In particular,1202-1204ofFIG.12denote portions of frame delay that are associated with a Rx-Tx differences as measured at the gNB and UE, respectively.

As will be appreciated from the disclosure above, NR native positioning technologies supported in 5G NR include DL-only positioning schemes (e.g., DL-TDOA, DL-AoD, etc.), UL-only positioning schemes (e.g., UL-TDOA, UL-AoA), and DL+UL positioning schemes (e.g., RTT with one or more neighboring base stations, or multi-RTT). In addition, Enhanced Cell-ID (E-CID) based on radio resource management (RRM) measurements is supported in 5G NR Rel-16.

OTDOA-based positioning schemes may be associated with various limitations. For example, GPS-sync is limited to a precision ˜50-100 ns (˜15-30 m). However, additional precision with OTDOA-based positioning requires tighter synchronization which is difficult to achieve.

For RTT-based positioning, a difference in TOA between UL and DL provides distance estimate between cell and UE (e.g., regardless of network synchronization). Multiple RTT measurements are used for triangulation (e.g., 3 or more cells, which is less than certain TDOA techniques), as depicted inFIG.11. In some systems, multi-cell RTT is the only conventional positioning technique capable of achieving positioning accuracy at ˜3 m when realistic network synchronization was involved.

As noted above, various device types may be characterized as UEs. Starting in 3GPP Rel. 17, a number of these UE types are being allocated a new UE classification denoted as “NR-Light” UEs or reduced capability (“RedCap”) UEs. Examples of UE types that fall under the RedCap classification include wearable devices (e.g., smart watches, etc.), industrial sensors, video cameras (e.g., surveillance cameras, etc.), and so on. Generally, the UE types grouped under the RedCap classification are associated with lower communicative capacity. For example, relative to ‘normal’ UEs (e.g., UEs not classified as RedCap), RedCap UEs may be limited in terms of maximum bandwidth (e.g., 5 MHz, 10 MHz, 20 MHz, etc.) for transmission and/or reception, maximum transmission power (e.g., 20 dBm, 14 dBm, etc.), number of receive antennas (e.g., 1 receive antenna, 2 receive antennas, etc.), and so on. Some RedCap UEs may also be sensitive in terms of power consumption (e.g., requiring a long battery life, such as several years) and may be highly mobile. Moreover, in some designs, it is generally desirable for RedCap UEs to co-exist with UEs implementing protocols such as eMBB, URLLC, LTE NB-IoT/MTC, and so on. In one particular example, industrial IoT (I-IOT) wireless sensors may be associated with intensive uplink traffic, moderate reliability and latency (e.g., non-URLLC), small packet size with a relatively long TX interval (e.g., low data rate), and high capacity (e.g., up to 1 UE per square meter).

In some designs, a transmission power for a RedCap UE may be reduced relative to other UE types. Hence, an effective coverage area and UL measurement quality for SRS-P transmissions is reduced, which may impact positioning of the RedCap UE. For example, it may not be possible for some or all neighbor cells to measure the SRS-P from the RedCap UE in some cases. For DL+UL-based positioning, such as multi-RTT, the UL may be the performance bottle-neck for a power limited UE, for example the RedCap UE.

If a positioning technique only requires the serving gNB to measure and report the UL measurement with respect to the UL power limited UE and still does not require high requirement on network synchronization (which is similar to RTT based positioning), high precision positioning could be achieved for these power limited UEs (for example, RedCap UE). For conventional multi-RTT based positioning, the non-serving gNB's UL measurements are needed for UE positioning. The poor quality of the UL measurement at the non-serving gNB(s) for power limited UE types may become a bottle neck for the accuracy of RTT-based positioning. However, the serving gNB is still very likely to have acceptable UL measurement quality.

One or more aspects of the disclosure are thereby directed to a serving base station (or gNB) of a UE that measures DL-PRS(s) from non-serving base station(s), and further measures an SRS-P from the UE that is associated with the same or different DL-PRS(s) from the non-serving base station(s). In some designs, such measurements at the serving base station may be used at a position estimation entity to calculate a position of the UE without reliance upon SRS-P measurements from the non-serving base station(s). Such aspects may provide various technical advantages, such as facilitating accurate positioning of the UE for scenarios where the SRS-P cannot be measured with sufficient quality at the non-serving base station(s), for example due to the UE being a RedCap UE with limited UL transmission power.

FIG.13illustrates an exemplary process1300of wireless communication, according to aspects of the disclosure. In an aspect, the process1300may be performed by BS302. In particular, the process1300may be performed by a BS (or gNB) configured as a serving base station with respect to a UE (such as UE302).

At1310, the serving base station (e.g., receiver352or362, positioning module388, etc.) measures a ToA of a first DL-PRS from a non-serving base station of the UE. In some designs, the first DL-PRS may arrive at the serving base station from the non-serving base station over a LOS path.

At1320, the serving base station (e.g., receiver352or362, positioning module388, etc.) measures a ToA of a UL-SRS-P from the UE that is transmitted in association with a second DL-PRS from the non-serving base station of the UE. In some designs, the first and second DL-PRS correspond to the same DL-PRS, (e.g., over different paths). In other designs, the first and second DL-PRS correspond to different time divisional multiplexed (TDMed) DL-PRSs (e.g., with a known offset between their respective transmission times).

At1330, the serving base station (e.g., transmitter354or364, network interface(s), data bus382, etc.) transmits measurement information based on the ToA measurements of the first DL-PRS and the UL-SRS-P to a position estimation entity. In some designs, the measurement information may comprise a time differential between the measured ToA of the first DL-PRS and the measured ToA of the UL-SRS-P. In some designs, the serving base station may further measure an angle of arrival (AoA) of the UL-SRS-P, and include the measured AoA is included as part of the measurement information. In some designs, the position estimation entity may correspond to the UE, in which case the measurement information may be transmitted via a wireless signal. In other designs, the position estimation entity may correspond to an external LMF component (e.g., at another BS, at core network such as LMF306, etc.), in which case the measurement information may be transmitted via network interface(s)380. In other designs, the position estimation entity may correspond to an internal LMF component integrated with the serving base station itself. In this case, the measurement information may be a transmission from one logical component of the serving base station to another logical component of the serving base station (e.g., over data bus382, etc.). In some designs, the measurement information may comprise a time differential between the measured ToAs of the DL-PRS and the UL-SRS-P. In other designs, the measurement information may comprise the measured ToAs from which the position estimation entity itself can derive the time differential.

FIG.14illustrates an exemplary process1400of wireless communication, according to aspects of the disclosure. In an aspect, the process1400may be performed by a position estimation entity (e.g., UE302, BS304, such as a serving or non-serving base station of UE302, or an external LMF component such as LMF306).

At1410, the position estimation entity (e.g., receiver312or322, data bus380, network interface(s)390, etc.) receives, from a serving base station of a UE, first measurement information indicative of a first time differential between a ToA of a first DL-PRS from a non-serving base station of the UE as measured the serving base station, and a ToA of a UL-SRS-P from the UE as measured the serving base station. In some designs, the first DL-PRS may arrive at the serving base station from the non-serving base station over a LOS path. In some designs, the first measurement information may comprise a time differential between the measured ToA of the first DL-PRS and the measured ToA of the UL-SRS-P. In other designs, the first measurement information may comprise the measured ToAs from which the position estimation entity itself can derive the time differential. In some designs, the first measurement information may comprise an AoA of the UL-SRS-P as measured or estimated at the serving base station. In some designs, the position estimation entity may correspond to the UE, in which case the first measurement information may be received via a wireless signal. In other designs, the position estimation entity may correspond to an external LMF component (e.g., at another BS, at core network such as LMF306, etc.), in which case the first measurement information may be transmitted via network interface(s)380. In other designs, the position estimation entity may correspond to an internal LMF component integrated with the serving base station itself. In this case, the first measurement information may be received at one logical component of the serving base station from another logical component of the serving base station (e.g., over data bus382, etc.).

At1420, the position estimation entity (e.g., receiver352or362, data bus334, network interface(s)390, etc.) receives, from the UE, second measurement information indicative of a second time differential between a ToA of second DL-PRS from the non-serving base station of the UE as measured at the UE and a time of transmission of the UL-SRS-P as measured at the UE. In some designs, the first and second DL-PRS correspond to the same DL-PRS, (e.g., over different paths). In other designs, the first and second DL-PRS correspond to different time divisional multiplexed (TDMed) DL-PRSs (e.g., with a known offset between their respective transmission times). In some designs, the position estimation entity may correspond to the UE, in which case the second measurement information may internally transferred at the UE from one component to another. In other designs, the position estimation entity may correspond to an external LMF component (e.g., at another BS, at core network such as LMF306, etc.), in which case the first measurement information may be transmitted via network interface(s)380. In other designs, the position estimation entity may correspond to an LMF component integrated with the serving base station. In this case, the second measurement information may be received from the UE via a wireless signal. In other designs, the position estimation entity may correspond to an external LMF component at some other entity (e.g., LMF306), in which case the second measurement information may be received from the UE via a wired backhaul connection (e.g., network interface(s)390).

At1430, the position estimation entity (e.g., processing system332or384or394, positioning module342or388or389, etc.) determines a positioning estimate of the UE based at least in part upon the first measurement information and the second measurement information. Various examples of how the determination (or calculation) of1430may be implemented are described below.

FIG.15illustrates a positioning scheme1500in accordance with an example implementation of the process1300-1400ofFIGS.13-14, respectively. InFIG.15, non-serving BS2of UE302transmits a first DL-PRS (denoted as DL-PRS[2]) to UE302over a first path, and non-serving BS2transmits a second DL-PRS (also denoted as DL-PRS[2], although the first and second DL-PRS may be the same signal or alternatively different TDMed signals in some aspects) over a second path (i.e., LOS path) to serving BS1of UE302. The first path is associated with a distance, RT, and the second (e.g., LOS) path is denoted with a distance, L. UE302transmits a UL-SRS-P to serving BS1over a third path associated with a distance, RR. In some designs, serving BS1may measure an AoA, θR, of the UL-SRS-P.

Referring toFIG.15, in an example, let Rsum=RT+RR. In this case, the range sum Rsum, may be used to locate the UE on the surface of an ellipsoid whose foci are the locations of BSs1and2. The time interval between the reception of LOS DL-PRS[2] transmitted by BS2and the reception of UL-SRS-P transmitted by UE302, and the UE reported Rx-Tx time difference “TUE_Rx→Tx” may be used to measure the range sum Rsum:
Rsum=(TRx_SRS−TRxLOS−TUE_Rx−Tx)*c+LEquation 1

In Equation 1, c is the speed of light, L is the distance between BS1and BS2, and TUE_Rx→Tx is the time difference between DL-PRS[2] reception at UE302and the corresponding SRS transmission, which is similar to the report in RTT-based positioning. L could be either known at the position estimation entity, or estimated through GPS or NR-based techniques. The target range from serving BS2perspective R could be computed as in Equation 2:

In some designs, AoA angle θRfrom serving BS2may be estimated by an antenna array at serving BS1based on the reception of UL-SRS-P.

In some designs, the legacy RTT-based positioning requires high quality SRS reception even at non-serving gNBs, which is may not be feasible for power limited UEs such as RedCap UEs. In accordance with some aspects, UE302need not transmit the UL-SRS-P with high power to reach non-serving cells, which is efficient for power limited UE, such as RedCap UE. Also, in an example, similar to RTT-based positioning, there is no high requirement for network synchronization. In a further example, the basic methodology described with respect toFIG.15can be expanded to multiple non-serving cells, as will be described in more detail below. In some designs, in the case with multiple cells, angle estimation may not be required for positioning.

FIG.16illustrates a timing sequence1600associated with the positioning scheme1500depicted inFIG.15in accordance with an aspect of the disclosure. InFIG.16, it is assumed that DL-PRS[2] on the first and second paths is associated with the same signal (i.e., a single transmission rather than two separate TDMed transmissions offset from each other). At t1, non-serving BS2transmit DL-PRS[2]1610, which is received at UE302at t2and at serving BS1at t3. UE302transmits UL-SRS-P1620at t4, which arrives at serving BS1at t5. The serving BS1may report TRx′→Rx1630(e.g., t5−t3, or the difference in Rx times for DL-PRS[1] and UL-SRS-P at serving BS1) as part of the first measurement information to the position estimation entity, and UE302may report TRx→Tx1612(e.g., t4−t2) as part of the second measurement information to the position estimation entity. The reporting of1612and1630may then be used to derive the position of UE302at the position estimation entity further based on θRas described above, in accordance with Equations 1-2.

Referring toFIGS.13-14, in some designs, the serving base station may further measure at least one additional ToA of at least one additional DL-PRS from at least one additional non-serving base station of the UE. Measurement information (e.g., the measured ToAs or associated differentials relative to the UL-SRS-P) based on the measurement of the at least one additional ToA of the at least one additional DL-PRS may further be reported to the position estimation entity. For example, the at least one additional DL-PRS is received at the serving base station from the at least one additional non-serving base station over at least one additional LOS path. In some designs, the serving base station may measure an AoA of the UL-SRS-P and include this measured AoA as part of the measurement information. However, for a multi-cell or multi-B S scenario, this AoA may alternatively be estimated rather than measured (e.g., via multilateration). In some designs, the AoA can be skipped altogether for the multi-cell or multi-BS scenario. Such aspects are described below with respect toFIG.17.

FIG.17illustrates a positioning scheme1700in accordance with another example implementation of the process1300-1400ofFIGS.13-14, respectively. The positioning scheme1700is an expanded version of positioning scheme1500where two additional non-serving BSs3and4are involved, and the UL-SRS-P AoA, θR, is optional.

Referring toFIG.17, similar toFIG.15, non-serving BS2of UE302transmits a first DL-PRS (denoted as DL-PRS[2]) to UE302over a first path, and non-serving BS2transmits a second DL-PRS (also denoted as DL-PRS[2], although the first and second DL-PRS may be the same signal or alternatively different TDMed signals in some aspects) over a second path (i.e., LOS path) to serving BS1of UE302. Likewise, non-serving BS3of UE302transmits a third DL-PRS (denoted as DL-PRS[3]) to UE302over a third path, and non-serving BS3transmits a fourth DL-PRS (also denoted as DL-PRS[3], although the third and fourth DL-PRSs may be the same signal or alternatively different TDMed signals in some aspects) over a fourth path (i.e., LOS path) to serving BS1of UE302. Likewise, non-serving BS4of UE302transmits a fifth DL-PRS (denoted as DL-PRS[4]) to UE302over a fifth path, and non-serving BS4transmits a sixth DL-PRS (also denoted as DL-PRS[4], although the fifth and sixth DL-PRSs may be the same signal or alternatively different TDMed signals in some aspects) over a sixth path (i.e., LOS path) to serving BS1of UE302. The first, third and fifth paths are each associated with a respective distance, RT, to serving BS1, and the second, fourth and sixth (e.g., LOS) paths may each be associated with respective distances, L, to the serving BS1. UE302transmits a UL-SRS-P to serving BS1over a seventh path associated with a distance, RR. In some designs, serving BS1may measure an AoA, θR, of the UL-SRS-P, although this is optional in the positioning scheme1700.

Referring toFIG.17, in some designs, UE302may receive the DL-PRSs, and then transmit the UL-SRS-P. UE302may report multiple Rx-Tx time differences “TUE_Rx→Tx” to the position estimation entity (e.g., through serving BS1). Serving BS1receives the DL-PRS from each of the three non-serving BSs2-4, as well as the UL-SRS-P from UE302. Serving BS1reports multiple time differences between the reception of UL-SRS-P and the reception of each respective DL-PRS “TRx_SRS−TRxLOS” to the position estimation entity. In some designs, the AoA, θR, may also be reported to the position estimation entity, although this is optional in the positioning scheme1700. The position estimation entity may then estimate Rsumin accordance with Equation 1 (above) for each of the three non-serving BSs2-4. The UE location can then be estimated through multilateration based on multiple Rsum.

Referring toFIG.17, in some designs, the legacy RTT-based positioning requires high quality SRS reception even at non-serving gNBs, which is may not be feasible for power limited UEs such as RedCap UEs. In accordance with some aspects, UE302need not transmit the UL-SRS-P with high power to reach non-serving cells, which is efficient for power limited UE, such as RedCap UE. Also, in an example, similar to RTT-based positioning, there is no high requirement for network synchronization. In a further example, the basic methodology described with respect toFIG.15can be expanded to multiple non-serving cells, as will be described in more detail below. In some designs, in the case with multiple cells, angle estimation may not be required for positioning.

Clause 1. A method of operating a serving base station of a user equipment (UE), comprising, comprising: measuring a time of arrival (ToA) of a first downlink positioning reference signal (DL-PRS) from a non-serving base station of the UE; measuring a ToA of an uplink sounding reference signal for positioning (UL-SRS-P) from the UE that is transmitted in association with a second DL-PRS from the non-serving base station of the UE; and transmitting measurement information based on the ToA measurements of the first DL-PRS and the UL-SRS-P to a position estimation entity.

Clause 2. The method of clause 1, wherein the first and second DL-PRS correspond to the same DL-PRS, or wherein the first and second DL-PRS correspond to different time divisional multiplexed (TDMed) or frequency division multiplexed (FDMed) DL-PRSs.

Clause 3. The method of any of clauses 1 to 2, wherein the first DL-PRS is received at the serving base station from the non-serving base station over a line-of-sight (LOS) path.

Clause 4. The method of any of clauses 1 to 3, wherein the measurement information comprises a time differential between the measured ToA of the first DL-PRS and the measured ToA of the UL-SRS-P.

Clause 5. The method of any of clauses 1 to 4, further comprising: measuring an angle of arrival (AoA) of the UL-SRS-P, wherein the measured AoA is included as part of the measurement information.

Clause 6. The method of any of clauses 1 to 5, further comprising: measuring at least one additional ToA of at least one additional DL-PRS from at least one additional non-serving base station of the UE, wherein the measurement information is further based on the measurement of the at least one additional ToA of the at least one additional DL-PRS.

Clause 7. The method of clause 6, wherein the at least one additional DL-PRS is received at the serving base station from the at least one additional non-serving base station over at least one additional LOS path.

Clause 8. The method of any of clauses 6 to 7, wherein the measurement information comprises at least one time differential between the measured at least one ToA of the at least one additional DL-PRS and the measured ToA of the UL-SRS-P.

Clause 9. The method of any of clauses 6 to 8, further comprising: measuring an angle of arrival (AoA) of the UL-SRS-P, wherein the measured AoA is included as part of the measurement information.

Clause 10. The method of any of clauses 6 to 9, further comprising: estimating an angle of arrival (AoA) of the UL-SRS-P relative to the serving base station via multilateration, wherein the estimated AoA is included as part of the measurement information.

Clause 11. The method of any of clauses 6 to 10, wherein an angle of arrival (AoA) of the UL-SRS-P is not included as part of the measurement information.

Clause 12. A method of operating a position estimation entity, comprising: receiving, from a serving base station of a user equipment (UE), first measurement information indicative of a first time differential between a time of arrival (ToA) of a first downlink positioning reference signal (DL-PRS) from a non-serving base station of the UE as measured the serving base station, and a ToA of an uplink sounding reference signal for positioning (UL-SRS-P) from the UE as measured the serving base station; receiving, from the UE, second measurement information indicative of a second time differential between a ToA of second DL-PRS from the non-serving base station of the UE as measured at the UE and a time of transmission of the UL-SRS-P as measured at the UE; and determining a positioning estimate of the UE based at least in part upon the first measurement information and the second measurement information.

Clause 13. The method of clause 12, wherein the first and second DL-PRS correspond to the same DL-PRS, or wherein the first and second DL-PRS correspond to different time divisional multiplexed (TDMed) or frequency division multiplexed (FDMed) DL-PRSs.

Clause 14. The method of any of clauses 12 to 13, wherein the first DL-PRS is received at the serving base station from the non-serving base station over a line-of-sight (LOS) path.

Clause 15. The method of any of clauses 12 to 14, wherein the first measurement information comprises the first time differential.

Clause 16. The method of any of clauses 12 to 15, wherein the first measurement information further comprises an angle of arrival (AoA) of the UL-SRS-P as measured or estimated at the serving base station.

Clause 17. The method of any of clauses 12 to 16, further comprising: receiving, from the serving base station of the UE, third measurement information indicative of at least one additional time differential between at least one additional ToA of at least one additional DL-PRS from at least one additional non-serving base station of the UE as measured at the serving base station, and the ToA of the UL-SRS-P as measured the serving base station, wherein the positioning estimate is further determined based at least in part upon the third measurement information.

Clause 18. The method of clause 17, wherein the at least one additional DL-PRS is received at the serving base station from the at least one additional non-serving base station over at least one additional LOS path.

Clause 19. The method of any of clauses 17 to 18, wherein the positioning estimate is determined based at least in part upon a measured or estimated of the UL-SRS-P relative to the serving base station.

Clause 20. The method of any of clauses 12 to 19, wherein the position estimation entity corresponds to the UE, or wherein the position estimation entity corresponds to a location management function (LMF) component integrated with, or separate from, the serving base station or the non-serving base station.

Clause 21. A serving base station of a user equipment (UE), comprising: a memory; at least one transceiver; and at least one processor communicatively coupled to the memory and the at least one transceiver, the at least one processor configured to: measure a time of arrival (ToA) of a first downlink positioning reference signal (DL-PRS) from a non-serving base station of the UE; measure a ToA of an uplink sounding reference signal for positioning (UL-SRS-P) from the UE that is transmitted in association with a second DL-PRS from the non-serving base station of the UE; and transmit, via the at least one transceiver, measurement information based on the ToA measurements of the first DL-PRS and the UL-SRS-P to a position estimation entity.

Clause 22. The serving base station of clause 21, wherein the first and second DL-PRS correspond to the same DL-PRS, or wherein the first and second DL-PRS correspond to different time divisional multiplexed (TDMed) or frequency division multiplexed (FDMed) DL-PRSs.

Clause 23. The serving base station of any of clauses 21 to 22, wherein the first DL-PRS is received at the serving base station from the non-serving base station over a line-of-sight (LOS) path.

Clause 24. The serving base station of any of clauses 21 to 23, wherein the measurement information comprises a time differential between the measured ToA of the first DL-PRS and the measured ToA of the UL-SRS-P.

Clause 25. The serving base station of any of clauses 21 to 24, wherein the at least one processor is further configured to: measure an angle of arrival (AoA) of the UL-SRS-P, wherein the measured AoA is included as part of the measurement information.

Clause 26. The serving base station of any of clauses 21 to 25, wherein the at least one processor is further configured to: measure at least one additional ToA of at least one additional DL-PRS from at least one additional non-serving base station of the UE, wherein the measurement information is further based on the measurement of the at least one additional ToA of the at least one additional DL-PRS.

Clause 27. The serving base station of clause 26, wherein the at least one additional DL-PRS is received at the serving base station from the at least one additional non-serving base station over at least one additional LOS path.

Clause 28. The serving base station of any of clauses 26 to 27, wherein the measurement information comprises at least one time differential between the measured at least one ToA of the at least one additional DL-PRS and the measured ToA of the UL-SRS-P.

Clause 29. The serving base station of any of clauses 26 to 28, wherein the at least one processor is further configured to: measure an angle of arrival (AoA) of the UL-SRS-P, wherein the measured AoA is included as part of the measurement information.

Clause 30. The serving base station of any of clauses 26 to 29, wherein the at least one processor is further configured to: estimate an angle of arrival (AoA) of the UL-SRS-P relative to the serving base station via multilateration, wherein the estimated AoA is included as part of the measurement information.

Clause 31. The serving base station of any of clauses 26 to 30, wherein an angle of arrival (AoA) of the UL-SRS-P is not included as part of the measurement information.

Clause 32. A position estimation entity, comprising: a memory; at least one transceiver; and at least one processor communicatively coupled to the memory and the at least one transceiver, the at least one processor configured to: receive, via the at least one transceiver, from a serving base station of a user equipment (UE), first measurement information indicative of a first time differential between a time of arrival (ToA) of a first downlink positioning reference signal (DL-PRS) from a non-serving base station of the UE as measured the serving base station, and a ToA of an uplink sounding reference signal for positioning (UL-SRS-P) from the UE as measured the serving base station; receive, via the at least one transceiver, from the UE, second measurement information indicative of a second time differential between a ToA of second DL-PRS from the non-serving base station of the UE as measured at the UE and a time of transmission of the UL-SRS-P as measured at the UE; and determine a positioning estimate of the UE based at least in part upon the first measurement information and the second measurement information.

Clause 33. The position estimation entity of clause 32, wherein the first and second DL-PRS correspond to the same DL-PRS, or wherein the first and second DL-PRS correspond to different time divisional multiplexed (TDMed) or frequency division multiplexed (FDMed) DL-PRSs.

Clause 34. The position estimation entity of any of clauses 32 to 33, wherein the first DL-PRS is received at the serving base station from the non-serving base station over a line-of-sight (LOS) path.

Clause 35. The position estimation entity of any of clauses 32 to 34, wherein the first measurement information comprises the first time differential.

Clause 36. The position estimation entity of any of clauses 32 to 35, wherein the first measurement information further comprises an angle of arrival (AoA) of the UL-SRS-P as measured or estimated at the serving base station.

Clause 37. The position estimation entity of any of clauses 32 to 36, wherein the at least one processor is further configured to: receive, via the at least one transceiver, from the serving base station of the UE, third measurement information indicative of at least one additional time differential between at least one additional ToA of at least one additional DL-PRS from at least one additional non-serving base station of the UE as measured at the serving base station, and the ToA of the UL-SRS-P as measured the serving base station, wherein the positioning estimate is further determined based at least in part upon the third measurement information.

Clause 38. The position estimation entity of clause 37, wherein the at least one additional DL-PRS is received at the serving base station from the at least one additional non-serving base station over at least one additional LOS path.

Clause 39. The position estimation entity of any of clauses 37 to 38, wherein the positioning estimate is determined based at least in part upon a measured or estimated of the UL-SRS-P relative to the serving base station.

Clause 40. The position estimation entity of any of clauses 32 to 39, wherein the position estimation entity corresponds to the UE, or wherein the position estimation entity corresponds to a location management function (LMF) component integrated with, or separate from, the serving base station or the non-serving base station.

Clause 41. A serving base station of a user equipment (UE), comprising: means for measuring a time of arrival (ToA) of a first downlink positioning reference signal (DL-PRS) from a non-serving base station of the UE; means for measuring a ToA of an uplink sounding reference signal for positioning (UL-SRS-P) from the UE that is transmitted in association with a second DL-PRS from the non-serving base station of the UE; and means for transmitting measurement information based on the ToA measurements of the first DL-PRS and the UL-SRS-P to a position estimation entity.

Clause 42. The serving base station of clause 41, wherein the first and second DL-PRS correspond to the same DL-PRS, or wherein the first and second DL-PRS correspond to different time divisional multiplexed (TDMed) or frequency division multiplexed (FDMed) DL-PRSs.

Clause 43. The serving base station of any of clauses 41 to 42, wherein the first DL-PRS is received at the serving base station from the non-serving base station over a line-of-sight (LOS) path.

Clause 44. The serving base station of any of clauses 41 to 43, wherein the measurement information comprises a time differential between the measured ToA of the first DL-PRS and the measured ToA of the UL-SRS-P.

Clause 45. The serving base station of any of clauses 41 to 44, further comprising: means for measuring an angle of arrival (AoA) of the UL-SRS-P, wherein the measured AoA is included as part of the measurement information.

Clause 46. The serving base station of any of clauses 41 to 45, further comprising: means for measuring at least one additional ToA of at least one additional DL-PRS from at least one additional non-serving base station of the UE, wherein the measurement information is further based on the measurement of the at least one additional ToA of the at least one additional DL-PRS.

Clause 47. The serving base station of clause 46, wherein the at least one additional DL-PRS is received at the serving base station from the at least one additional non-serving base station over at least one additional LOS path.

Clause 48. The serving base station of any of clauses 46 to 47, wherein the measurement information comprises at least one time differential between the measured at least one ToA of the at least one additional DL-PRS and the measured ToA of the UL-SRS-P.

Clause 49. The serving base station of any of clauses 46 to 48, further comprising: means for measuring an angle of arrival (AoA) of the UL-SRS-P, wherein the measured AoA is included as part of the measurement information.

Clause 50. The serving base station of any of clauses 46 to 49, further comprising: means for estimating an angle of arrival (AoA) of the UL-SRS-P relative to the serving base station via multilateration, wherein the estimated AoA is included as part of the measurement information.

Clause 51. The serving base station of any of clauses 46 to 50, wherein an angle of arrival (AoA) of the UL-SRS-P is not included as part of the measurement information.

Clause 52. A position estimation entity, comprising: means for receiving, from a serving base station of a user equipment (UE), first measurement information indicative of a first time differential between a time of arrival (ToA) of a first downlink positioning reference signal (DL-PRS) from a non-serving base station of the UE as measured the serving base station, and a ToA of an uplink sounding reference signal for positioning (UL-SRS-P) from the UE as measured the serving base station; means for receiving, from the UE, second measurement information indicative of a second time differential between a ToA of second DL-PRS from the non-serving base station of the UE as measured at the UE and a time of transmission of the UL-SRS-P as measured at the UE; and means for determining a positioning estimate of the UE based at least in part upon the first measurement information and the second measurement information.

Clause 53. The position estimation entity of clause 52, wherein the first and second DL-PRS correspond to the same DL-PRS, or wherein the first and second DL-PRS correspond to different time divisional multiplexed (TDMed) or frequency division multiplexed (FDMed) DL-PRSs.

Clause 54. The position estimation entity of any of clauses 52 to 53, wherein the first DL-PRS is received at the serving base station from the non-serving base station over a line-of-sight (LOS) path.

Clause 55. The position estimation entity of any of clauses 52 to 54, wherein the first measurement information comprises the first time differential.

Clause 56. The position estimation entity of any of clauses 52 to 55, wherein the first measurement information further comprises an angle of arrival (AoA) of the UL-SRS-P as measured or estimated at the serving base station.

Clause 57. The position estimation entity of any of clauses 52 to 56, further comprising: means for receiving, from the serving base station of the UE, third measurement information indicative of at least one additional time differential between at least one additional ToA of at least one additional DL-PRS from at least one additional non-serving base station of the UE as measured at the serving base station, and the ToA of the UL-SRS-P as measured the serving base station, wherein the positioning estimate is further determined based at least in part upon the third measurement information.

Clause 58. The position estimation entity of clause 57, wherein the at least one additional DL-PRS is received at the serving base station from the at least one additional non-serving base station over at least one additional LOS path.

Clause 59. The position estimation entity of any of clauses 57 to 58, wherein the positioning estimate is determined based at least in part upon a measured or estimated of the UL-SRS-P relative to the serving base station.

Clause 60. The position estimation entity of any of clauses 52 to 59, wherein the position estimation entity corresponds to the UE, or wherein the position estimation entity corresponds to a location management function (LMF) component integrated with, or separate from, the serving base station or the non-serving base station.

Clause 61. A non-transitory computer-readable medium storing computer-executable instructions that, when executed by a serving base station of a user equipment (UE), cause the serving base station to: measure a time of arrival (ToA) of a first downlink positioning reference signal (DL-PRS) from a non-serving base station of the UE; measure a ToA of an uplink sounding reference signal for positioning (UL-SRS-P) from the UE that is transmitted in association with a second DL-PRS from the non-serving base station of the UE; and transmit measurement information based on the ToA measurements of the first DL-PRS and the UL-SRS-P to a position estimation entity.

Clause 62. The non-transitory computer-readable medium of clause 61, wherein the first and second DL-PRS correspond to the same DL-PRS, or wherein the first and second DL-PRS correspond to different time divisional multiplexed (TDMed) or frequency division multiplexed (FDMed) DL-PRSs.

Clause 63. The non-transitory computer-readable medium of any of clauses 61 to 62, wherein the first DL-PRS is received at the serving base station from the non-serving base station over a line-of-sight (LOS) path.

Clause 64. The non-transitory computer-readable medium of any of clauses 61 to 63, wherein the measurement information comprises a time differential between the measured ToA of the first DL-PRS and the measured ToA of the UL-SRS-P.

Clause 65. The non-transitory computer-readable medium of any of clauses 61 to 64, wherein the one or more instructions further cause the serving base station to: measure an angle of arrival (AoA) of the UL-SRS-P, wherein the measured AoA is included as part of the measurement information.

Clause 66. The non-transitory computer-readable medium of any of clauses 61 to 65, wherein the one or more instructions further cause the serving base station to: measure at least one additional ToA of at least one additional DL-PRS from at least one additional non-serving base station of the UE, wherein the measurement information is further based on the measurement of the at least one additional ToA of the at least one additional DL-PRS.

Clause 67. The non-transitory computer-readable medium of clause 66, wherein the at least one additional DL-PRS is received at the serving base station from the at least one additional non-serving base station over at least one additional LOS path.

Clause 68. The non-transitory computer-readable medium of any of clauses 66 to 67, wherein the measurement information comprises at least one time differential between the measured at least one ToA of the at least one additional DL-PRS and the measured ToA of the UL-SRS-P.

Clause 69. The non-transitory computer-readable medium of any of clauses 66 to 68, wherein the one or more instructions further cause the serving base station to: measure an angle of arrival (AoA) of the UL-SRS-P, wherein the measured AoA is included as part of the measurement information.

Clause 70. The non-transitory computer-readable medium of any of clauses 66 to 69, wherein the one or more instructions further cause the serving base station to: estimate an angle of arrival (AoA) of the UL-SRS-P relative to the serving base station via multilateration, wherein the estimated AoA is included as part of the measurement information.

Clause 71. The non-transitory computer-readable medium of any of clauses 66 to 70, wherein an angle of arrival (AoA) of the UL-SRS-P is not included as part of the measurement information.

Clause 72. A non-transitory computer-readable medium storing computer-executable instructions that, when executed by a position estimation entity, cause the position estimation entity to: receive, from a serving base station of a user equipment (UE), first measurement information indicative of a first time differential between a time of arrival (ToA) of a first downlink positioning reference signal (DL-PRS) from a non-serving base station of the UE as measured the serving base station, and a ToA of an uplink sounding reference signal for positioning (UL-SRS-P) from the UE as measured the serving base station; receive, from the UE, second measurement information indicative of a second time differential between a ToA of second DL-PRS from the non-serving base station of the UE as measured at the UE and a time of transmission of the UL-SRS-P as measured at the UE; and determine a positioning estimate of the UE based at least in part upon the first measurement information and the second measurement information.

Clause 73. The non-transitory computer-readable medium of clause 72, wherein the first and second DL-PRS correspond to the same DL-PRS, or wherein the first and second DL-PRS correspond to different time divisional multiplexed (TDMed) or frequency division multiplexed (FDMed) DL-PRSs.

Clause 74. The non-transitory computer-readable medium of any of clauses 72 to 73, wherein the first DL-PRS is received at the serving base station from the non-serving base station over a line-of-sight (LOS) path.

Clause 75. The non-transitory computer-readable medium of any of clauses 72 to 74, wherein the first measurement information comprises the first time differential.

Clause 76. The non-transitory computer-readable medium of any of clauses 72 to 75, wherein the first measurement information further comprises an angle of arrival (AoA) of the UL-SRS-P as measured or estimated at the serving base station.

Clause 77. The non-transitory computer-readable medium of any of clauses 72 to 76, wherein the one or more instructions further cause the position estimation entity to: receive, from the serving base station of the UE, third measurement information indicative of at least one additional time differential between at least one additional ToA of at least one additional DL-PRS from at least one additional non-serving base station of the UE as measured at the serving base station, and the ToA of the UL-SRS-P as measured the serving base station, wherein the positioning estimate is further determined based at least in part upon the third measurement information.

Clause 78. The non-transitory computer-readable medium of clause 77, wherein the at least one additional DL-PRS is received at the serving base station from the at least one additional non-serving base station over at least one additional LOS path.

Clause 79. The non-transitory computer-readable medium of any of clauses 77 to 78, wherein the positioning estimate is determined based at least in part upon a measured or estimated of the UL-SRS-P relative to the serving base station.

Clause 80. The non-transitory computer-readable medium of any of clauses 72 to 79, wherein the position estimation entity corresponds to the UE, or wherein the position estimation entity corresponds to a location management function (LMF) component integrated with, or separate from, the serving base station or the non-serving base station.