Reconfigurable Intelligent Surface (RIS)-assisted Round Trip Time (RTT)-based User Equipment (UE) Positioning

Abstract

Techniques for positioning are disclosed. In one aspect, a positioning entity receives a report indicating an operation mode of a reconfigurable intelligent surface (RIS) associated with at least one base station, receives a transmit-to-receive (Tx-Rx) time difference measurement for a network node involved in a round-trip time (RTT) positioning session with a user equipment (UE), determines a receive-to-receive (Rx-Tx) time difference measurement for the UE, where the Rx-Tx time difference measurement represents a difference between a reception time at the UE of a downlink positioning reference signal from the RIS and a transmission time from the UE of an uplink positioning reference signal toward the RIS, and calculates a distance between the UE and the RIS based at least in part on the Tx-Rx time difference measurement and the Rx-Tx time difference measurement.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This patent application claims the benefit of Greek Application No. 20210100180, entitled "RECONFIGURABLE INTELLIGENT SURFACE (RIS) AIDED ROUND-TRIP-TIME (RTT)-BASED USER EQUIPMENT (UE) POSITIONING," filed March 22, 2021, which is assigned to the assignee of the present application and is expressly incorporated herein by reference in its entirety.

[0002] Aspects of the present disclosure relate generally to wireless communications. [Background technology]

[0003] Wireless communication systems have evolved through various generations, including first-generation analog wireless telephone service (1G), second-generation (2G) digital wireless telephone service (including interim 2.5G and 2.75G networks), third-generation (3G) high-speed data, Internet-enabled wireless service, and fourth-generation (4G) service (e.g., Long Term Evolution (LTE) or WiMax). Currently, there are many different types of wireless communication systems in use, including cellular systems and personal communications services (PCS) systems. Examples of known cellular systems include the Cellular Analog Advanced Mobile Phone System (AMPS), and digital cellular systems based on code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), Global System for Mobile Communications (GSM), etc.

[0004] The fifth-generation (5G) wireless standard, known as New Radio (NR), promises higher data rates, more connections, and better coverage, among other improvements. According to the Next Generation Mobile Network Alliance, the 5G standard is designed to provide data rates of tens of megabits per second to each of tens of thousands of users, delivering 1 gigabit per second to dozens of workers on an office floor. To support large-scale sensor deployments, hundreds of thousands of simultaneous connections should be supported. Therefore, the spectral efficiency of 5G mobile communications should be significantly enhanced compared to the current 4G standard. Furthermore, signaling efficiency should be enhanced and latency significantly reduced compared to current standards. Summary of the Invention [Means for solving the problem]

[0005] The following presents a simplified summary related to one or more aspects disclosed herein. As such, the following summary is not intended to be an extensive overview related to all contemplated aspects, nor is it intended to identify key or critical elements related to all contemplated aspects or to delineate the scope related to any particular aspect. As such, the following summary has the sole purpose of presenting some concepts related to one or more aspects related to the mechanisms disclosed herein in a simplified form prior to the detailed description presented below.

[0006] In one aspect, a method of positioning performed by a positioning entity includes receiving a report indicating an operation mode of a reconfigurable intelligent surface (RIS) associated with at least one base station; receiving a transmit-to-receive (Tx-Rx) time difference measurement for a network node involved in a round-trip time (RTT) positioning session with a user equipment (UE); determining a receive-to-receive (Rx-Tx) time difference measurement for the UE, wherein the Rx-Tx time difference measurement represents a difference between a reception time at the UE of a downlink positioning reference signal from the RIS and a transmission time from the UE of an uplink positioning reference signal towards the RIS; and calculating a distance between the UE and the RIS based at least in part on the Tx-Rx time difference measurement and the Rx-Tx time difference measurement.

[0007] In one aspect, a positioning entity includes a memory and at least one processor communicatively coupled to the memory, wherein the at least one processor is configured to: receive a report indicating an operating mode of a reconfigurable intelligent surface (RIS) associated with at least one base station; receive a transmit-to-receive (Tx-Rx) time difference measurement for a network node involved in a round-trip time (RTT) positioning session with a user equipment (UE); determine a receive-to-receive (Rx-Tx) time difference measurement for the UE, wherein the Rx-Tx time difference measurement represents a difference between a reception time at the UE of a downlink positioning reference signal from the RIS and a transmission time from the UE of an uplink positioning reference signal towards the RIS; and calculate a distance between the UE and the RIS based at least in part on the Tx-Rx time difference measurement and the Rx-Tx time difference measurement.

[0008] In one aspect, the positioning entity includes means for receiving a report indicating an operating mode of a reconfigurable intelligent surface (RIS) associated with at least one base station; means for receiving a transmit-to-receive (Tx-Rx) time difference measurement for a network node involved in a round-trip time (RTT) positioning session with a user equipment (UE); means for determining a receive-to-receive (Rx-Tx) time difference measurement for the UE, wherein the Rx-Tx time difference measurement represents a difference between a reception time at the UE of a downlink positioning reference signal from the RIS and a transmission time from the UE of an uplink positioning reference signal towards the RIS; and means for calculating a distance between the UE and the RIS based at least in part on the Tx-Rx time difference measurement and the Rx-Tx time difference measurement.

[0009] In one aspect, a non-transitory computer-readable medium storing computer-executable instructions includes computer-executable instructions, comprising: at least one instruction to instruct a positioning entity to receive a report indicating an operating mode of a reconfigurable intelligent surface (RIS) associated with at least one base station; at least one instruction to instruct the positioning entity to receive transmit-to-receive (Tx-Rx) time difference measurements for network nodes involved in a round-trip time (RTT) positioning session with a user equipment (UE); at least one instruction to instruct the positioning entity to determine a receive-to-transmit (Rx-Tx) time difference measurement for the UE, wherein the Rx-Tx time difference measurement represents a difference between a reception time at the UE of a downlink positioning reference signal from the RIS and a transmission time from the UE of an uplink positioning reference signal towards the RIS; and at least one instruction to instruct the positioning entity to calculate a distance between the UE and the RIS based at least in part on the Tx-Rx time difference measurement and the Rx-Tx time difference measurement.

[0010] Other objects and advantages associated with the embodiments disclosed herein will become apparent to those skilled in the art based on the accompanying drawings and detailed description.

[0011] The accompanying drawings are presented to aid in the explanation of various aspects of the present disclosure and are provided solely for the purpose of illustrating the aspects and not for the purpose of limiting the aspects. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 illustrates an exemplary wireless communication system according to aspects of the present disclosure. [Figure 2A] FIG. 1 illustrates an exemplary wireless network structure according to aspects of the present disclosure. [Figure 2B] FIG. 1 illustrates an exemplary wireless network structure according to aspects of the present disclosure. [Figure 3A] 1 is a simplified block diagram of several sample aspects of components that may be employed in a user equipment (UE) and configured to support communication as taught herein; [Figure 3B] 1 is a simplified block diagram of several sample aspects of components that may be employed in a base station and configured to support communication as taught herein; [Figure 3C] 1 is a simplified block diagram of several sample aspects of components that may be employed in a network entity and configured to support communications as taught herein; [Figure 4] FIG. 1 illustrates an example system for wireless communication using a reconfigurable intelligent surface (RIS), according to aspects of the present disclosure. [Figure 5] FIG. 2 is a diagram of an example architecture of a RIS, according to an aspect of the present disclosure. [Figure 6] FIG. 1 illustrates an example technique for determining a location of a UE using information obtained from multiple base stations. [Figure 7] 1 illustrates an example timing diagram of round trip time (RTT) measurement signals exchanged between a base station and a UE, according to an aspect of the present disclosure. [Figure 8] 10A-10C illustrate example timing of RTT measurement signals exchanged between a base station and a UE according to an aspect of the present disclosure. [Figure 9] FIG. 10 is a diagram of a first type of RTT positioning procedure between a base station, a UE, and a RIS according to an aspect of the present disclosure. [Figure 10] FIG. 10 is a diagram of a second type of RTT positioning procedure between a base station, a UE, and a RIS according to an aspect of the present disclosure. [Figure 11] FIG. 1 illustrates an exemplary method for positioning according to aspects of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0013] Aspects of the present disclosure are provided in the following description and related drawings, directed to various examples provided for illustrative purposes. Alternative aspects may be devised without departing from the scope of the present disclosure. Additionally, well-known elements of the present disclosure will not be described in detail or will be omitted so as not to obscure the relevant details of the present disclosure.

[0014] The words "exemplary" and / or "example" are used herein to mean "serving as an example, instance, or illustration." Any aspect described herein as "exemplary" and / or "example" is not necessarily to be construed as preferred or advantageous over other aspects. Likewise, the term "aspects of the present disclosure" does not require that all aspects of the present disclosure include the discussed feature, advantage or mode of operation.

[0015] Those skilled in the art will appreciate that the information and signals described below may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the following description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof, depending in part on the particular application, in part on the desired design, in part on the corresponding technology, etc.

[0016] Further, many aspects are described in terms of sequences of actions to be performed by, for example, elements of a computing device. It will be recognized that the various actions described herein may be performed by specific circuitry (e.g., an application-specific integrated circuit (ASIC)), by program instructions executed by one or more processors, or a combination of both. Additionally, the sequences of actions described herein may be considered to be embodied entirely in any form of non-transitory computer-readable storage medium storing a corresponding set of computer instructions that, when executed, cause or instruct the associated processor(s) of the device to perform the functionality described herein. Accordingly, various aspects of the present disclosure may be embodied in a number of different forms, all of which are contemplated to be within the scope of the claimed subject matter. Additionally, for each aspect described herein, the corresponding form of any such aspect may be described herein, for example, as “logic configured to” perform the described actions.

[0017] The terms “user equipment” (UE) and “base station,” as used herein, are not intended to be specific to or otherwise limited to any particular radio access technology (RAT) unless otherwise specified. In general, a UE may be any wireless communication device (e.g., a mobile phone, a router, a tablet computer, a laptop computer, a consumer asset tracking device, a wearable (e.g., a smart watch, smart glasses, an augmented reality (AR) / virtual reality (VR) headset, etc.), a vehicle (e.g., an automobile, a motorcycle, a bicycle, etc.), an Internet of Things (IoT) device, etc.) used by a user to communicate over a wireless communication network. A UE may be mobile or may be stationary (e.g., at some times) and may communicate with a radio access network (RAN). As used herein, the term “UE” may be referred to interchangeably as an “access terminal” or “AT,” a “client device,” a “wireless device,” a “subscriber device,” a “subscriber terminal,” a “subscriber station,” a “user terminal” or “UT,” a “mobile device,” a “mobile terminal,” a “mobile station,” or variations thereof. Generally, a UE can communicate with a core network via a RAN, through which the UE can be connected to external networks such as the Internet and to other UEs. Of course, other mechanisms for connecting to the core network and / or the Internet are also possible for a UE, such as via a wired access network, a wireless local area network (WLAN) network (e.g., based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 specifications, etc.), etc.

[0018] A base station may operate according to one of several RATs with which it communicates with the UE, depending on the network in which the UE is deployed, and may alternatively be referred to as an access point (AP), network node, Node B, evolved Node B (eNB), next-generation eNB (ng-eNB), New Radio (NR) Node B (also referred to as gNB or gNode B), etc. Base stations may be used primarily to support wireless access by UEs, including supporting data, voice, and / or signaling connections for supported UEs. In some systems, base stations may provide purely edge node signaling functionality, while in other systems, base stations may provide additional control and / or network management functions. A communication link through which a UE can send signals to a base station is called an uplink (UL) channel (e.g., a reverse traffic channel, a reverse control channel, an access channel, etc.). A communication link through which a base station can send signals to a UE is called a downlink (DL) channel or a forward link channel (e.g., a paging channel, a control channel, a broadcast channel, a forward traffic channel, etc.). As used herein, the term Traffic Channel (TCH) can refer to either an uplink / reverse traffic channel or a downlink / forward traffic channel.

[0019] The term "base station" can refer to a single physical transmit / receive point (TRP) or multiple physical TRPs, which may or may not be collocated. For example, when the term "base station" refers to a single physical TRP, the physical TRP may be an antenna of the base station corresponding to the base station's cell (or several cell sectors). When the term "base station" refers to multiple collocated physical TRPs, the physical TRPs may be an array of antennas of the base station (e.g., as in a multiple-input multiple-output (MIMO) system or when the base station employs beamforming). When the term "base station" refers to multiple non-collocated physical TRPs, the physical TRPs 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, a non-co-located physical TRP may be a serving base station that receives measurement reports from the UE and neighboring base stations whose reference radio frequency (RF) signals the UE is measuring. Because a TRP is a point from which a base station transmits and receives wireless signals, as used herein, references to transmission from or reception at a base station should be understood as references to a particular TRP of the base station.

[0020] In some implementations that support UE positioning, a base station may not support wireless access by the UE (e.g., may not support data, voice, and / or signaling connections for the UE), but instead may transmit reference signals to the UE to be measured by the UE and / or may receive and measure signals transmitted by the UE. Such a base station may be referred to as a positioning beacon (e.g., when transmitting signals to the UE) and / or a location measurement unit (e.g., when receiving and measuring signals from the UE).

[0021] An "RF signal" comprises electromagnetic waves of a given frequency that transport information through 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, due to the propagation characteristics of RF signals through a multipath channel, the receiver may receive multiple "RF signals" corresponding to each transmitted RF signal. The same transmitted RF signal over different paths between the transmitter and receiver is sometimes referred to as a "multipath" RF signal.

[0022] 1 illustrates an exemplary wireless communication system 100 according to an aspect of the present disclosure. The wireless communication system 100 (sometimes referred to as a wireless wide area network (WWAN)) may include various base stations 102 (labeled “BS”) and various UEs 104. The base stations 102 may include macrocell base stations (high-power cellular base stations) and / or small cell base stations (low-power cellular base stations). In one aspect, the macrocell base stations may include eNBs and / or ng-eNBs, where the wireless communication system 100 corresponds to an LTE network, or gNBs, where the wireless communication system 100 corresponds to an NR network, or a combination of both, and the small cell base stations may include femtocells, picocells, microcells, etc.

[0023] The base stations 102 may collectively form a RAN and may interface with a core network 170 (e.g., Evolved Packet Core (EPC) or 5G Core (5GC)) through backhaul links 122 and to one or more location servers 172 (e.g., a Location Management Function (LMF) or a Secure User Plane Localization (SUPL) Location Platform (SLP)) through the core network 170. The location servers 172 may be part of the core network 170 or may be external to the core network 170. In addition to other functions, the base stations 102 may perform functions related to one or more of the following: forwarding user data, radio channel encryption and decryption, 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 tracing, RAN Information Management (RIM), paging, positioning, and distribution of alert messages. The base stations 102 may communicate with each other directly or indirectly (e.g., through EPC / 5GC) via backhaul links 134, which may be wired or wireless.

[0024] The base stations 102 may communicate wirelessly with the UEs 104. Each of the base stations 102 may provide communication coverage for a respective geographic coverage area 110. In one aspect, one or more cells may be supported by the base stations 102 in each geographic coverage area 110. A “cell” is a logical communication entity used for communication with a base station (e.g., over some frequency resources referred to as a carrier frequency, component carrier, carrier, band, etc.) and may be associated with an identifier (e.g., a physical cell identifier (PCI), a virtual cell identifier (VCI), a cell global identifier (CGI)) to distinguish between cells operating over the same or different carrier frequencies. In some cases, different cells may be configured according to different protocol types (e.g., machine type communication (MTC), narrowband IoT (NB-IoT), enhanced mobile broadband (eMBB), or others) that may provide access to different types of UEs. Because a cell is supported by a particular base station, the term “cell” can refer to one or both of the logical communication entity and its supporting base station, depending on the context. In some cases, the term "cell" may refer to the geographic coverage area (e.g., sector) of a base station, so long as the carrier frequency can be detected and used for communication within some portion of the geographic coverage area 110.

[0025] The geographic coverage areas 110 of neighboring macrocell base stations 102 may partially overlap (e.g., within handover regions), but some of the geographic coverage areas 110 may be significantly overlapped by larger geographic coverage areas 110. For example, a small cell (SC) base station 102' may have a geographic coverage area 110' that significantly overlaps with the geographic coverage area 110 of one or more macrocell base stations 102. A network including both small cell and macrocell base stations may be referred to as a heterogeneous network. A heterogeneous network may also include Home eNBs (HeNBs) that may serve restricted groups called closed subscriber groups (CSGs).

[0026] The communication link 120 between the base station 102 and the UE 104 may include uplink (also called reverse link) transmissions from the UE 104 to the base station 102, and / or downlink (also called forward link) transmissions from the base station 102 to the UE 104. The communication link 120 may use MIMO antenna techniques, including spatial multiplexing, beamforming, and / or transmit diversity. The communication link 120 may be over one or more carrier frequencies. The allocation of carriers may be asymmetric for the downlink and uplink (e.g., more or fewer carriers may be allocated for the downlink than for the uplink).

[0027] The wireless communication system 100 may further include a wireless local area network (WLAN) access point (AP) 150 communicating with a WLAN station (STA) 152 via a communication link 154 in an unlicensed frequency spectrum (e.g., 5 GHz). When communicating in the unlicensed frequency spectrum, the WLAN STA 152 and / or the WLAN AP 150 may perform a clear channel assessment (CCA) or listen-before-talk (LBT) procedure before communicating to determine whether a channel is available.

[0028] The small cell base station 102' may operate in a licensed and / or unlicensed frequency spectrum. When operating in an unlicensed frequency spectrum, the small cell base station 102' may employ LTE or NR technology and may use the same 5 GHz unlicensed frequency spectrum used by the WLAN AP 150. A small cell base station 102' employing LTE / 5G in an unlicensed frequency spectrum may extend coverage to and / or increase the capacity of an access network. NR in an unlicensed spectrum may be referred to as NR-U. LTE in an unlicensed spectrum may be referred to as LTE-U, licensed assisted access (LAA), or MultiFire.

[0029] The wireless communication system 100 may further include a millimeter-wave (mmW) base station 180 in communication with the UE 182 and capable of operating within mmW and / or quasi-mmW frequencies. Extremely high frequency (EHF) is the RF portion of the electromagnetic spectrum. EHF ranges from 30 GHz to 300 GHz and has wavelengths between 1 and 10 millimeters. Radio waves in this band are sometimes referred to as millimeter waves. Sub-mmW may extend down to frequencies of 3 GHz, with wavelengths of 100 millimeters. The very high frequency (SHF) band extends between 3 GHz and 30 GHz, also known as centimeter waves. Communications using the mmW / quasi-mmW radio frequency bands have high path loss and relatively short distances. The mmW base station 180 and the UE 182 may utilize beamforming (transmit and / or receive) over the mmW communication link 184 to compensate for the significant path loss and short distances. It will be appreciated that in alternative configurations, one or more base stations 102 may also transmit using mmW or quasi-mmW and beamforming. Therefore, it will be appreciated that the above illustrations are merely exemplary and should not be construed as limiting the various aspects disclosed herein.

[0030] Transmit beamforming is a technique for focusing an RF signal in a particular direction. Traditionally, when a network node (e.g., a base station) broadcasts an RF signal, it broadcasts the signal in all directions (omnidirectionally). With transmit beamforming, the network node determines where a given target device (e.g., UE) is located (relative to the transmitting network node) and projects a stronger downlink RF signal in that particular direction, thereby providing a faster and more powerful RF signal (in terms of data rate) to the receiving device. To change the directionality of the RF signal when transmitting, the network node can control the phase and relative amplitude of the RF signal at each of one or more transmitters broadcasting the RF signal. For example, the network node may use an array of antennas (called a “phased array” or “antenna array”) that creates a beam of RF waves that can be “steered” to points in different directions without actually moving the antennas. Specifically, RF currents from the transmitter are fed to individual antennas with the appropriate phase relationship so that the radio waves from the separate antennas add together to enhance radiation in desired directions while suppressing or eliminating radiation in undesired directions.

[0031] A transmit beam may be quasi-colocated, meaning that the transmit beam appears to a receiver (e.g., a UE) to have the same parameters regardless of whether the network node's own transmit antennas are physically colocated. In NR, there are four types of quasi-colocation (QCL) relationships. In particular, a given type of QCL relationship means that some parameters for a target reference RF signal on a target beam can be derived from information about a source reference RF signal on a source beam. If the source reference RF signal is QCL Type A, the receiver can use the source reference RF signal to estimate the Doppler shift, Doppler spread, mean delay, and delay spread of the target reference RF signal transmitted on the same channel. If the source reference RF signal is QCL Type B, the receiver can use the source reference RF signal to estimate the Doppler shift and Doppler spread of the target reference RF signal transmitted on the same channel. If the source reference RF signal is QCL Type C, the receiver can use the source reference RF signal to estimate the Doppler shift and mean delay of the target reference RF signal transmitted on the same channel. If the source reference RF signal is QCL Type D, the receiver can use the source reference RF signal to estimate spatial reception parameters of a target reference RF signal transmitted on the same channel.

[0032] In receive beamforming, a receiver uses receive beams to amplify RF signals detected on a given channel. For example, the receiver can increase the gain setting and / or adjust the phase setting of an antenna array in a particular direction to amplify (e.g., increase the gain level of) RF signals received from that direction. Thus, when a receiver is said to beamform in a direction, it means that the beam gain in that direction is greater than the beam gains along other directions, or that the beam gain in that direction is greatest compared to the beam gains in that direction of all other receive beams available to the receiver. This results in a stronger received signal strength (e.g., reference signal received power (RSRP), reference signal received quality (RSRQ), signal-to-interference-plus-noise ratio (SINR), etc.) of RF signals received from that direction.

[0033] The receive beams may be spatially related. Spatial relationship means that parameters for a transmit beam for a second reference signal may be derived from information about the receive beam for the first reference signal. For example, a UE may use a particular receive beam to receive one or more reference downlink reference signals (e.g., a positioning reference signal (PRS), a tracking reference signal (TRS), a phase tracking reference signal (PTRS), a cell-specific reference signal (CRS), a channel state information reference signal (CSI-RS), a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a synchronization signal block (SSB), etc.) from a base station. The UE can then form a transmit beam for sending one or more uplink reference signals (e.g., an uplink positioning reference signal (UL-PRS), a sounding reference signal (SRS), a demodulation reference signal (DMRS), a PTRS, etc.) to that base station based on the parameters of the receive beam.

[0034] Note that a "downlink" beam may be either a transmit beam or a receive beam, depending on the entity that forms it. For example, if a base station forms a downlink beam to transmit a reference signal to a UE, the downlink beam is a transmit beam. However, if the UE forms a downlink beam, the downlink beam is a receive beam for receiving a downlink reference signal. Similarly, an "uplink" beam may be either a transmit beam or a receive beam, depending on the entity that forms it. For example, if a base station forms an uplink beam, the uplink beam is an uplink receive beam, and if the UE forms an uplink beam, the uplink beam is an uplink transmit beam.

[0035] In 5G, the frequency spectrum in which wireless nodes (e.g., base station 102 / 180, UE 104 / 182) operate is divided into multiple frequency ranges: FR1 (450 MHz to 6000 MHz), FR2 (24250 MHz to 52600 MHz), FR3 (above 52600 MHz), and FR4 (between FR1 and FR2). In a multi-carrier system such as 5G, one of the carrier frequencies is called the “primary carrier” or “anchor carrier” or “primary serving cell” or “PCell,” and the remaining carrier frequencies are called “secondary carriers” or “secondary serving cells” or “SCells.” In carrier aggregation, the anchor carrier is the carrier operating on the primary frequency (e.g., FR1) utilized by the UE 104 / 182 and the cell on which the UE 104 / 182 either performs an initial radio resource control (RRC) connection establishment procedure or initiates an RRC connection re-establishment procedure. The primary carrier carries all common and UE-specific control channels and may be a carrier among licensed frequencies (although this is not always the case). The secondary carrier is a carrier operating on a second frequency (e.g., FR2) that may be configured once an RRC connection is established between the UE 104 and the anchor carrier and may be used to provide additional radio resources. In some cases, the secondary carrier may be a carrier among unlicensed frequencies. Because both the primary uplink carrier and the primary downlink carrier are typically UE-specific, the secondary carrier may contain only necessary signaling information and signals; for example, UE-specific signaling information and signals may not be present in the secondary carrier. This means that different UEs 104 / 182 in a cell may have different downlink primary carriers. The same is true for the uplink primary carrier. The network can change the primary carrier of any UE 104 / 182 at any time. This is done, for example, to balance the load on different carriers.Since a "serving cell" (whether PCell or SCell) corresponds to a carrier frequency / component carrier over which several base stations are communicating, terms such as "cell," "serving cell," "component carrier," and "carrier frequency" may be used interchangeably.

[0036] For example, still referring to FIG. 1 , one of the frequencies utilized by the macrocell base station 102 may be an anchor carrier (i.e., “PCell”), and other frequencies utilized by the macrocell base station 102 and / or the mmW base station 180 may be secondary carriers (“SCells”). Simultaneous transmission and / or reception of multiple carriers allows the UE 104 / 182 to significantly increase its data transmission and / or data reception rates. For example, two aggregated 20 MHz carriers in a multi-carrier system would theoretically lead to a two-fold increase in data rate (i.e., 40 MHz) compared to that achieved with a single 20 MHz carrier.

[0037] Wireless communications system 100 may further include a UE 164, which may communicate with macrocell base station 102 via communications link 120 and / or with mmW base station 180 via mmW communications link 184. For example, macrocell base station 102 may support a PCell and one or more SCells for UE 164, and mmW base station 180 may support one or more SCells for UE 164.

[0038] In the example of FIG. 1 , one or more Earth-orbiting satellite positioning system (SPS) space vehicles (SVs) 112 (e.g., satellites) may be used as independent sources of location information for any of the illustrated UEs (shown in FIG. 1 as a single UE 104 for simplicity). The UE 104 may include one or more dedicated SPS receivers specifically designed to receive SPS signals 124 to derive geolocation information from the SVs 112. An SPS typically includes a system of transmitters (e.g., SVs 112) positioned to enable receivers (e.g., UEs 104) to determine their location on or above the Earth based, at least in part, on signals received from the transmitters (e.g., SPS signals 124). Such transmitters typically transmit signals marked with a repeating pseudorandom noise (PN) code of a set number of chips. While typically located within the SVs 112, transmitters may sometimes be located on ground-based control stations, base stations 102, and / or other UEs 104.

[0039] Use of SPS signals 124 may be augmented by various satellite-based augmentation systems (SBAS) that may be associated with or otherwise enabled for use with one or more global and / or regional navigation satellite systems. For example, SBAS may include augmentation systems that provide integrity information, differential corrections, and the like, such as the Wide Area Augmentation System (WAAS), the European Geostationary Navigation Overlay Service (EGNOS), the Multifunction Satellite Augmentation System (MSAS), the Global Positioning System (GPS)-Aided Geo-Augmented Navigation, or the GPS and Geo-Augmented Navigation System (GAGAN). Thus, as used herein, SPS may include any combination of one or more global and / or regional navigation satellite systems and / or augmentation systems, and SPS signals 124 may include SPS, SPS-like signals, and / or other signals associated with such one or more SPSs.

[0040] The wireless communication system 100 may further include one or more UEs, such as a UE 190, that indirectly connect to one or more communication networks via one or more device-to-device (D2D) peer-to-peer (P2P) links (referred to as “sidelinks”). In the example of FIG. 1, the UE 190 has a D2D P2P link 192 with one of the UEs 104 connected to one of the base stations 102 (e.g., through which the UE 190 may indirectly obtain cellular connectivity), and a D2D P2P link 194 with a WLAN STA 152 connected to a WLAN AP 150 (through which the UE 190 may indirectly obtain WLAN-based Internet connectivity). In one example, the D2D P2P links 192 and 194 may be supported using any well-known D2D RAT, such as LTE Direct (LTE-D), WiFi Direct (WiFi-D), Bluetooth®, etc.

[0041] 2A shows an exemplary wireless network structure 200. For example, a 5GC 210 (also referred to as a Next Generation Core (NGC)) can be viewed functionally as a control plane function 214 (e.g., UE registration, authentication, network access, gateway selection, etc.) and a user plane function 212 (e.g., UE gateway function, access to data network, IP routing, etc.), which operate cooperatively to form a core network. A user plane interface (NG-U) 213 and a control plane interface (NG-C) 215 connect a gNB 222 to the 5GC 210, specifically to the control plane function 214 and the user plane function 212. In an additional configuration, an ng-eNB 224 may also be connected to the 5GC 210 via the NG-C 215 to the control plane function 214 and the NG-U 213 to the user plane function 212. Additionally, the ng-eNB 224 may communicate directly with the gNB 222 via a backhaul connection 223. In some configurations, the Next Generation RAN (NG-RAN) 220 may have only one or more gNBs 222, while other configurations include one or more of both an ng-eNB 224 and a gNB 222. Either the gNB 222 or the ng-eNB 224 may be in communication with the UE 204 (e.g., any of the UEs shown in FIG. 1). Another optional aspect may include a location server 230, which may be in communication with the 5GC 210 to provide location assistance to the UE 204. The location servers 230 may be implemented as multiple separate servers (e.g., physically separate servers, different software modules on a single server, different software modules spread across multiple physical servers, etc.), or alternatively, each may correspond to a single server. The location server 230 may be configured to support one or more location services for UEs 204 that can connect to the location server 230 via the core network 5GC 210 and / or via the Internet (not shown). Furthermore, the location server 230 may be integrated into a component of the core network, or alternatively, may be external to the core network.

[0042] 2B shows another exemplary wireless network structure 250. The 5GC 260 (which may correspond to the 5GC 210 in FIG. 2A ) may be viewed functionally as a control plane function provided by an access and mobility management function (AMF) 264 and a user plane function provided by a user plane function (UPF) 262, which operate cooperatively to form a core network (i.e., the 5GC 260). A user plane interface 263 and a control plane interface 265 connect the ng-eNB 224 to the 5GC 260, specifically to the UPF 262 and the AMF 264, respectively. In an additional configuration, the gNB 222 may also be connected to the 5GC 260 via the control plane interface 265 to the AMF 264 and the user plane interface 263 to the UPF 262. Furthermore, the ng-eNB 224 may communicate directly with the gNB 222 via the backhaul connection 223, with or without gNB direct connectivity to the 5GC 260. In some configurations, the NG-RAN 220 may have only one or more gNBs 222, while other configurations include one or more of both an ng-eNB 224 and a gNB 222. Either the gNB 222 or the ng-eNB 224 may communicate with the UE 204 (e.g., any of the UEs shown in FIG. 1). The base stations of the NG-RAN 220 communicate with the AMF 264 over an N2 interface and with the UPF 262 over an N3 interface.

[0043] The AMF 264 functions include registration management, connection management, reachability management, mobility management, lawful intercept, transport for session management (SM) messages between the UE 204 and a session management function (SMF) 266, a transparent proxy service for routing SM messages, access authentication and access authorization, transport for short message service (SMS) messages between the UE 204 and a short message service function (SMSF) (not shown), and a security anchor functionality (SEAF). The AMF 264 also interacts with an authentication server function (AUSF) (not shown) and the UE 204 to receive intermediate keys established as a result of the UE 204 authentication process. In the case of UMTS (Universal Mobile Telecommunications System) subscriber identity module (USIM)-based authentication, the AMF 264 retrieves security material from the AUSF. The AMF 264 functions also include security context management (SCM). The SCM receives keys from the SEAF that the SCM uses to derive access network-specific keys. The functionality of the AMF 264 also includes location service management for regulatory services, transport for location service messages between the UE 204 and the LMF 270 (acting as the location server 230), transport for location service messages between the NG-RAN 220 and the LMF 270, Evolved Packet System (EPS) bearer identifier allocation for interworking with EPS, and UE 204 mobility event notification. In addition, the AMF 264 also supports functionality for non-3GPP (Third Generation Partnership Project) access networks.

[0044] The functions of the UPF 262 include acting as an anchor point for intra- / inter-RAT mobility (when applicable), acting as an outer protocol data unit (PDU) session point for interconnection to a data network (not shown), routing and forwarding packets, 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) processing for the user plane (e.g., uplink / downlink rate enforcement, reflective QoS marking in the downlink), uplink traffic validation (service data flow (SDF) to QoS flow mapping), transport-level packet marking in the uplink and downlink, downlink packet buffering and downlink data notification triggering, and sending and forwarding one or more "end markers" to the source RAN node. The UPF 262 may also support the transfer of location service messages over the user plane between the UE 204 and a location server such as the SLP 272.

[0045] The functions of the SMF 266 include session management, UE Internet Protocol (IP) address allocation and management, selection and control of user plane functions, configuration of traffic steering in the UPF 262 to route traffic to the appropriate destination, control of policy enforcement and part of QoS, and downlink data notification. The interface through which the SMF 266 communicates with the AMF 264 is called the N11 interface.

[0046] Another optional aspect may include an LMF 270, which may be in communication with the 5GC 260 to provide location assistance to the UE 204. The LMF 270 may be implemented as multiple separate servers (e.g., physically separate servers, different software modules on a single server, different software modules spread across multiple physical servers, etc.), or alternatively, each may correspond to a single server. The LMF 270 may be configured to support one or more location services for UEs 204 that can connect to the LMF 270 via the core network 5GC 260 and / or via the Internet (not shown). The SLP 272 may support similar functions as the LMF 270, while the LMF 270 may communicate with the AMF 264, the NG-RAN 220, and the UE 204 via the control plane (e.g., using interfaces and protocols intended to convey signaling messages rather than voice or data), and the SLP 272 may communicate with the UE 204 and external clients (not shown in FIG. 2B) via the user plane (e.g., using protocols intended to carry voice and / or data, such as Transmission Control Protocol (TCP) and / or IP).

[0047] 3A, 3B, and 3C illustrate several example components (represented by corresponding blocks) that may be incorporated within a UE 302 (which may correspond to any of the UEs described herein), a base station 304 (which may correspond to any of the base stations described herein), and a network entity 306 (which may correspond to or embody any of the network functions described herein, including location server 230 and LMF 270) to support file transmission operations as taught herein. It will be appreciated that these components may be implemented in different types of devices in different implementations (e.g., in an ASIC, in a system-on-chip (SoC), etc.). The illustrated components may also be incorporated into other devices in a communication system. For example, other devices in the system may include components similar to the illustrated components to provide similar functionality. Also, a given device may include one or more of the components. For example, a device may include multiple transceiver components that enable the device to operate on multiple carriers and / or communicate via different technologies.

[0048] The UE 302 and base station 304 each include a wireless wide area network (WWAN) transceiver 310 and 350, respectively, that provides means for communicating (e.g., means for transmitting, means for receiving, means for measuring, means for tuning, means for refraining from transmitting, etc.) over one or more wireless communications networks (not shown), such as an NR network, an LTE network, a GSM network, etc. The WWAN transceivers 310 and 350 may be connected to one or more antennas 316 and 356, 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 communications medium of interest (e.g., some set of time / frequency resources within a particular frequency spectrum). The WWAN transceivers 310 and 350 may be variously configured to transmit and encode signals 318 and 358 (e.g., messages, indications, information, etc.), respectively, and conversely, to receive and decode signals 318 and 358 (e.g., messages, indications, information, pilots, etc.), respectively, in accordance with a designated RAT. In particular, the WWAN transceivers 310 and 350 include one or more transmitters 314 and 354, respectively, for transmitting and encoding signals 318 and 358, respectively, and one or more receivers 312 and 352, respectively, for receiving and decoding signals 318 and 358, respectively.

[0049] The UE 302 and base station 304 also, at least in some cases, include one or more short-range wireless transceivers 320 and 360, respectively. The short-range wireless transceivers 320 and 360 may be connected to one or more antennas 326 and 366, respectively, and may provide means for communicating (e.g., means for transmitting, means for receiving, means for measuring, means for tuning, means for refraining from transmitting, etc.) 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, Zigbee, Z-Wave, PC5, dedicated short-range communications (DSRC), wireless access for vehicular environments (WAVE), near field communications (NFC), etc.) over a target wireless communications medium. The short-range wireless transceivers 320 and 360 may be variously configured to transmit and encode signals 328 and 368 (e.g., messages, indications, information, etc.), respectively, and conversely, to receive and decode signals 328 and 368 (e.g., messages, indications, information, pilots, etc.), respectively, in accordance with a designated RAT. In particular, the short-range wireless transceivers 320 and 360 include one or more transmitters 324 and 364, respectively, to transmit and encode signals 328 and 368, respectively, and one or more receivers 322 and 362, respectively, to receive and decode signals 328 and 368, respectively. As specific examples, the short-range wireless transceivers 320 and 360 may be WiFi transceivers, Bluetooth® transceivers, Zigbee® and / or Z-Wave® transceivers, NFC transceivers, or vehicle-to-vehicle (V2V) and / or vehicle-to-everything (V2X) transceivers.

[0050] Transceiver circuitry including at least one transmitter and at least one receiver may in some implementations comprise an integrated device (e.g., embodied as transmitter and receiver circuitry in a single communications device), in some implementations comprise separate transmitter and receiver devices, or in other implementations may be embodied in other ways. In one aspect, a transmitter may include or be coupled to multiple antennas (e.g., antennas 316, 326, 356, 366), such as an antenna array that enables each device to perform transmit “beamforming” as described herein. Similarly, a receiver may include or be coupled to multiple antennas (e.g., antennas 316, 326, 356, 366), such as an antenna array that enables each device to perform receive beamforming as described herein. In one aspect, transmitters and receivers may share multiple identical antennas (e.g., antennas 316, 326, 356, 366), such that each device can only receive or transmit at a given time, but not both at the same time. The wireless communication device of the UE 302 and / or base station 304 (e.g., one or both of the transceivers 310 and 320 and / or 350 and 360) may also include a network listen module (NLM) or the like for performing various measurements.

[0051] The UE 302 and base station 304 also, at least in some cases, include satellite positioning system (SPS) receivers 330 and 370. The SPS receivers 330 and 370 may be connected to one or more antennas 336 and 376, respectively, and may provide a means for receiving and / or measuring SPS signals 338 and 378, respectively, such as Global Positioning System (GPS) signals, Global Navigation Satellite System (GLONASS) signals, Galileo signals, Beidou signals, Navigation Satellite System of India (NAVIC), Quasi-Zenith Satellite System (QZSS), etc. The SPS receivers 330 and 370 may comprise any suitable hardware and / or software for receiving and processing the SPS signals 338 and 378, respectively. The SPS receivers 330 and 370 request information and actions from other systems as appropriate and perform the necessary calculations to determine the position of the UE 302 and base station 304 using the obtained measurements, via any suitable SPS algorithms.

[0052] The base station 304 and the network entity 306 each include at least one network interface 380 and 390, respectively, that provide means for communicating (e.g., means for transmitting, means for receiving, etc.) with other network entities. For example, the network interfaces 380 and 390 (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 interfaces 380 and 390 may be implemented as transceivers configured to support wire-based or wireless signal communication. This communication may involve, for example, sending and receiving messages, parameters, and / or other types of information.

[0053] The UE 302, base station 304, and network entity 306 also include other components that may be used in conjunction with operations as disclosed herein. The UE 302 includes processor circuitry implementing a processing system 332, e.g., for providing functionality related to wireless positioning and for providing other processing functionality. The base station 304 includes a processing system 384, e.g., for providing functionality related to wireless positioning and for providing other processing functionality. The network entity 306 includes a processing system 394, e.g., for providing functionality related to wireless positioning and for providing other processing functionality. Thus, the processing systems 332, 384, and 394 may provide means for processing, such as means for determining, means for calculating, means for receiving, means for transmitting, means for indicating, etc. In one aspect, processing systems 332, 384, and 394 may include one or more processors, such as, for example, one or more general-purpose processors, multi-core processors, ASICs, digital signal processors (DSPs), field programmable gate arrays (FPGAs), other programmable logic devices or processing circuitry, or various combinations thereof.

[0054] The UE 302, the base station 304, and the network entity 306 include memory circuitry implementing memory components 340, 386, and 396, respectively (e.g., each including a memory device) for maintaining information (e.g., information indicative of reserved resources, thresholds, parameters, etc.). Thus, the memory components 340, 386, and 396 may provide a means for storing, a means for retrieving, a means for retaining, etc. In some cases, the UE 302, the base station 304, and the network entity 306 may include positioning components 342, 388, and 398, respectively. The positioning components 342, 388, and 398 may be hardware circuits that are part of or coupled to the processing systems 332, 384, and 394, respectively, that, when executed, cause the UE 302, the base station 304, and the network entity 306 to perform the functionality described herein. In other aspects, positioning components 342, 388, and 398 may be external to processing systems 332, 384, and 394 (e.g., may be part of a modem processing system, may be integrated with another processing system, etc.). Alternatively, positioning components 342, 388, and 398 may be memory modules stored in memory components 340, 386, and 396, respectively, that, when executed by processing systems 332, 384, and 394 (or modem processing system, another processing system, etc.), cause UE 302, base station 304, and network entity 306 to perform the functionality described herein. FIG. 3A shows possible locations for positioning component 342, which may be part of WWAN transceiver 310, memory component 340, processing system 332, or any combination thereof, or may be a stand-alone component. FIG. 3B illustrates possible locations for a positioning component 388, which may be part of the WWAN transceiver 350, memory component 386, processing system 384, or any combination thereof, or may be a stand-alone component.FIG. 3C illustrates possible locations for a positioning component 398, which may be part of the network interface 390, memory component 396, processing system 394, or any combination thereof, or may be a stand-alone component.

[0055] The UE 302 may include one or more sensors 344 coupled to the processing system 332 to provide a means for sensing or detecting motion and / or orientation information that is independent of motion data derived from signals received by the WWAN transceiver 310, the short-range wireless transceiver 320, and / or the SPS receiver 330. By way of example, the sensors 344 may include an accelerometer (e.g., a microelectromechanical system (MEMS) device), a gyroscope, a geomagnetic sensor (e.g., a compass), an altimeter (e.g., a barometric altimeter), and / or any other type of motion detection sensor. Moreover, the sensors 344 may include multiple different types of devices and combine their outputs to provide motion information. For example, the sensors 344 may use a combination of a multi-axis accelerometer and an orientation sensor to provide the ability to calculate a position in a 2D and / or 3D coordinate system.

[0056] Additionally, the UE 302 includes a user interface 346 that provides a means for providing an indication to a user (e.g., an audio and / or visual indication) and / or receiving user input (e.g., upon user actuation of a sensing device such as a keypad, touch screen, microphone, etc.). Although not shown, the base station 304 and the network entity 306 may also include user interfaces.

[0057] Referring more particularly to the processing system 384, on the downlink, IP packets from the network entity 306 may be provided to the processing system 384. The processing system 384 may implement functionality for an RRC layer, a Packet Data Convergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer, and a Medium Access Control (MAC) layer. The processing system 384 may provide RRC layer functionality related to broadcasting of system information (e.g., Master Information Block (MIB), System Information Block (SIB)), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter-RAT mobility, and measurement configuration for UE measurement reporting; PDCP layer functionality related to header compression / decompression, security (encryption, decryption, integrity protection, integrity verification), and handover support functions; RLC layer functionality related to transfer of upper layer PDUs, error correction through automatic repeat request (ARQ), concatenation, segmentation, and reassembly of RLC service data units (SDUs), resegmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality related to mapping between logical channels and transport channels, scheduling information reporting, error correction, priority handling, and logical channel prioritization.

[0058] The transmitter 354 and receiver 352 may implement Layer 1 (L1) functionality related to various signal processing functions. Layer 1, which includes the physical (PHY) layer, may include error detection on transport channels, forward error correction (FEC) coding / decoding of transport channels, interleaving, rate matching, mapping onto physical channels, modulation / demodulation of physical channels, and MIMO antenna processing. The transmitter 354 handles mapping to signal constellations based on various modulation schemes (e.g., binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), M-phase shift keying (M-PSK), M-ary quadrature amplitude modulation (M-QAM)). The coded and modulated symbols may then be split into parallel streams. Each stream may then be mapped to an orthogonal frequency division multiplexing (OFDM) subcarrier, multiplexed with a reference signal (e.g., a pilot) in the time and / or frequency domain, and then combined together using an inverse fast Fourier transform (IFFT) to generate a physical channel carrying a time-domain OFDM symbol stream. The OFDM symbol stream is spatially precoded to generate multiple spatial streams. Channel estimates from a channel estimator may be used to determine coding and modulation schemes and for spatial processing. The channel estimates may be derived from a reference signal and / or channel condition feedback transmitted by the UE 302. Each spatial stream may then be provided to one or more different antennas 356. The transmitter 354 may modulate an RF carrier with the respective spatial stream for transmission.

[0059] At the UE 302, the receiver 312 receives signals through its respective antenna 316. The receiver 312 recovers the information modulated onto the RF carriers and provides the information to the processing system 332. The transmitter 314 and receiver 312 perform Layer 1 functionality related to various signal processing functions. The receiver 312 may perform spatial processing on the information to recover any spatial streams destined for the UE 302. If multiple spatial streams are destined for the UE 302, they may be combined into a single OFDM symbol stream by the receiver 312. The receiver 312 then 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, as well as the reference signal, are recovered and demodulated by determining the signal constellation point that was most likely transmitted by the base station 304. These soft decisions may be based on channel estimates calculated by a channel estimator. The soft decisions are then decoded and deinterleaved to recover the data and control signals originally transmitted on the physical channel by the base station 304. The data and control signals are then provided to a processing system 332 that performs Layer 3 (L3) and Layer 2 (L2) functionality.

[0060] In the uplink, the processing system 332 performs demultiplexing between transport and logical channels, packet reassembly, decryption, header decompression, and control signal processing to recover IP packets from the core network. The processing system 332 is also responsible for error detection.

[0061] Similar to the functionality described with respect to downlink transmissions by the base station 304, the processing system 332 provides RRC layer functionality related to system information (e.g., MIB, SIB) acquisition, RRC connection, and measurement reporting; PDCP layer functionality related to header compression / decompression and security (encryption, decryption, integrity protection, integrity verification); RLC layer functionality related to transfer of upper layer PDUs, error correction via ARQ, concatenation, segmentation, and reassembly of RLC SDUs, resegmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality related to mapping between logical channels and transport channels, multiplexing of MAC SDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction via hybrid automatic repeat request (HARQ), priority handling, and logical channel prioritization.

[0062] Channel estimates derived by the channel estimator from a reference signal or feedback transmitted by the base station 304 may be used by the transmitter 314 to select an appropriate coding and modulation scheme and to facilitate spatial processing. The spatial streams generated by the transmitter 314 may be provided to different antennas 316. The transmitter 314 may modulate an RF carrier with each spatial stream for transmission.

[0063] Uplink transmissions are processed at the base station 304 in a manner similar to that described with respect to the receiver function at the UE 302. The receiver 352 receives the signal through its respective antenna 356. The receiver 352 recovers the information modulated onto the RF carrier and provides the information to the processing system 384.

[0064] In the uplink, the processing system 384 performs demultiplexing between transport and logical channels, packet reassembly, decryption, header decompression, and control signal processing to recover IP packets from the UE 302. The IP packets from the processing system 384 may be provided to the core network. The processing system 384 is also responsible for error detection.

[0065] For convenience, the UE 302, the base station 304, and / or the network entity 306 are illustrated in Figures 3A-3C as including various components that may be configured in accordance with various examples described herein. However, it will be appreciated that the illustrated blocks may have different functionality in different designs.

[0066] The various components of the UE 302, the base station 304, and the network entity 306 may communicate with each other via data buses 334, 382, ​​and 392, respectively. The components of FIGS. 3A-3C may be implemented in various ways. In some implementations, the components of FIGS. 3A-3C may 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), where each circuit may use and / or incorporate at least one memory component for storing information or executable code used by the circuit to provide its functionality. For example, some or all of the functionality represented by blocks 310-346 may be performed by the processor and memory components of the UE 302 (e.g., by execution of appropriate code and / or by appropriate configuration of the processor components). Similarly, some or all of the functionality represented by blocks 350-388 may be performed by the processor and memory components of the base station 304 (e.g., by execution of appropriate code and / or by appropriate configuration of the processor components). Additionally, some or all of the functionality represented by blocks 390-398 may be implemented by the processor and memory components of the network entity 306 (e.g., by execution of appropriate code and / or by appropriate configuration of the processor components). For simplicity, various operations, acts, and / or functions are described herein as being performed "by the UE," "by the base station," "by the network entity," etc. However, it will be appreciated that such operations, acts, and / or functions may actually be performed by particular components or combinations of components of the UE 302, base station 304, network entity 306, etc., such as processing systems 332, 384, 394, transceivers 310, 320, 350, and 360, memory components 340, 386, and 396, positioning components 342, 388, and 398, etc.

[0067] FIG. 4 illustrates an example system 400 for wireless communications using a reconfigurable intelligent surface (RIS) 410 according to an aspect of the present disclosure. The RIS (e.g., RIS 410) is a two-dimensional surface comprising a large number of low-cost, low-power, mostly passive reflective elements whose characteristics are not static but are reconfigurable (by software). For example, by carefully adjusting the phase shifts of the reflective elements (using software), the scattering, absorption, reflection, and diffraction properties of the RIS can be altered over time. In that way, the electromagnetic (EM) properties of the RIS can be designed to collect wireless signals from a transmitter (e.g., a base station, a UE, etc.) and passively beamform them toward a target receiver (e.g., another base station, another UE, etc.). In the example of FIG. 4, a first base station 402-1 controls the reflective properties of the RIS 410 to communicate with a first UE 404-1.

[0068] The goal of RIS technology is to create a smart radio environment where wireless propagation conditions are co-designed with physical layer signaling. This expanded functionality of system 400 can provide technical benefits in several scenarios.

[0069] 4, a first base station 402-1 (e.g., any of the base stations described herein) is attempting to transmit downlink wireless signals to a first UE 404-1 and a second UE 404-2 (e.g., any two of the UEs described herein, collectively UEs 404) on multiple downlink transmit beams labeled “0,” “1,” “2,” and “3.” However, unlike the second UE 404-2, the first UE 404-1 is behind an obstruction 420 (e.g., a building, a hill, or another type of obstruction) and is therefore unable to receive wireless signals on what would otherwise be a line-of-sight (LOS) beam from the first base station 402-1, i.e., the downlink transmit beam labeled “2.” In this scenario, the first base station 402-1 may instead use a downlink transmit beam labeled "1" to transmit wireless signals to the RIS 410, and may configure the RIS 410 to reflect / beamform the incident wireless signals toward the first UE 404-1. The first base station 402-1 may thereby transmit wireless signals around the obstacle 420.

[0070] It should be noted that the first base station 402-1 may also configure the RIS 410 for use by the first UE 404-1 in the uplink. In that case, the first base station 402-1 may configure the RIS 410 to reflect uplink signals from the first UE 404-1 to the first base station 402-1, thereby allowing the first UE 404-1 to transmit uplink signals around the obstacle 420.

[0071] As another example scenario in which the system 400 may provide a technical advantage, the first base station 402-1 may be aware that an obstacle 420 may create a "dead zone," i.e., a geographic area where downlink wireless signals from the first base station 402-1 are so attenuated that they cannot be reliably detected by UEs (e.g., the first UE 404-1) within that area. In this scenario, the first base station 402-1 may configure the RIS 410 to reflect downlink wireless signals into the dead zone to provide coverage to UEs that may be located in the dead zone, including UEs that the first base station 402-1 is unaware of.

[0072] A RIS (e.g., RIS 410) may be designed to operate in either a first mode (referred to as “Mode 1”) in which the RIS operates as a reconfigurable mirror (i.e., a reflector), or a second mode (referred to as “Mode 2”) in which the RIS operates as a receiver and transmitter (similar to the amplify and forward functionality of a relay node). Some RISs may be designed to operate in either Mode 1 or Mode 2, while other RISs may be designed to operate only in Mode 1 or Mode 2. Mode 1 RISs are assumed to have negligible group delay, while Mode 2 RISs have non-negligible group delay due to being equipped with limited baseband processing capabilities. Due to their greater processing capabilities compared to Mode 1 RISs, Mode 2 RISs may, at least in some cases, be able to calculate and report their transmit-to-receive (Tx-Rx) time difference measurements (i.e., the difference between the time a signal is reflected toward the UE and the time the signal is received back from the UE). In the example of FIG. 4, RIS 410 may be either a Mode 1 RIS or a Mode 2 RIS.

[0073] 4 also shows a second base station 402-2 that may transmit downlink wireless signals to one or both of the UEs 404. As an example, the first base station 402-1 may be a serving base station for the UEs 404, and the second base station 402-2 may be a neighboring base station. The second base station 402-2 may transmit downlink positioning reference signals to one or both of the UEs 404 as part of a positioning procedure involving the UEs 404. Alternatively or additionally, the second base station 402-2 may be a secondary cell for one or both of the UEs 404. In some cases, the second base station 402-2 may also be able to reconfigure the RIS 410, provided that the RIS 410 is not then controlled by the first base station 402-1.

[0074] FIG. 5 is a diagram of an exemplary architecture of a RIS 500 according to an embodiment of the present disclosure. The RIS 500, which may correspond to the RIS 410 in FIG. 4, may be a mode 1 RIS. As shown in FIG. 5, the RIS 500 mainly consists of a flat surface 510 and a controller 520. The flat surface 510 may be constructed of one or more layers of material. In the example of FIG. 5, the flat surface 510 may consist of three layers. In this case, the outer layer has multiple reflective elements 512 printed on a dielectric substrate to directly act on the incident signal. The middle layer is a copper panel to avoid signal / energy leakage. The final layer is a circuit board used to adjust the reflection coefficient of the reflective elements 512 and is operated by a controller 520. The controller 520 may be a low-power processor such as a field-programmable gate array (FPGA).

[0075] In a typical operating scenario, the optimal reflection coefficients for the RIS 500 are calculated at a base station (e.g., the first base station 402-1 in FIG. 4) and then sent to the controller 520 over a dedicated feedback link. The design of the reflection coefficients relies on channel state information (CSI), which is updated only when the CSI changes, which is on a timescale much longer than the data symbol duration. Therefore, a low rate of information exchange is sufficient for the dedicated control link, which can be implemented using low-cost copper wire or a simple, cost-effective wireless transceiver.

[0076] Each reflective element 512 is coupled to a p-type intrinsic n-type (PIN) positive-intrinsic negative diode 514. In addition, bias lines 516 connect each reflective element 512 in a row to a controller 520. By controlling the voltage through the bias lines 516, the PIN diodes 514 can be switched between an "on" mode and an "off" mode. This can achieve a phase shift difference of π (pi) in radians. To increase the number of phase shift levels, more PIN diodes 514 can be coupled to each reflective element 512.

[0077] A RIS such as the RIS 500 has important advantages for practical implementation. For example, the reflective element 512 merely passively reflects the incident signal without any sophisticated signal processing operations that would require RF transceiver hardware. Therefore, compared to conventional active transmitters, the RIS 500 can operate at orders of magnitude lower costs in terms of hardware and power consumption. Additionally, due to the passive nature of the reflective element 512, the RIS 500 can be fabricated with low weight and limited layer thickness, and thus can be easily installed on walls, ceilings, signs, streetlights, and the like. Furthermore, the RIS 500 operates naturally in full-duplex (FD) mode without self-interference or introducing thermal noise. Therefore, the RIS 500 can achieve higher spectral efficiency than an active half-duplex (HD) relay, despite the signal processing complexity of the RIS 500 being less than that of an active FD relay, which requires sophisticated self-interference cancellation.

[0078] NR supports several cellular network-based positioning techniques, including downlink-based positioning methods, uplink-based positioning methods, and downlink- and uplink-based positioning methods. Downlink-based positioning methods include observed time difference of arrival (OTDOA) in LTE, downlink time difference of arrival (DL-TDOA) in NR, and downlink angle-of-departure (DL-AoD) in NR. In an OTDOA or DL-TDOA positioning procedure, a UE measures the differences between the times of arrival (ToA) of reference signals (e.g., PRS, TRS, CSI-RS, SSB, etc.) received from pairs of base stations, called reference signal time difference (RSTD) or time difference of arrival (TDOA) measurements, and reports them to a positioning entity. More specifically, the UE receives identifiers (IDs) of a reference base station (e.g., a serving base station) and multiple non-reference base stations in assistance data. The UE then measures RSTD between the reference base station and each of the non-reference base stations. Based on the known locations of the base stations involved and the RSTD measurements, the positioning entity can estimate the location of the UE.

[0079] For DL-AoD positioning, the positioning entity uses beam reports from the UE of received signal strength measurements of multiple downlink transmit beams to determine the angle between the UE and the transmitting base station. The positioning entity can then estimate the location of the UE based on the determined angle and the known location of the transmitting base station.

[0080] Uplink-based positioning methods include uplink time difference of arrival (UL-TDOA) and uplink angle-of-arrival (UL-AoA). UL-TDOA is similar to DL-TDOA, but is based on uplink reference signals (e.g., SRS) transmitted by the UE. For UL-AoA positioning, one or more base stations measure the received signal strength of one or more uplink reference signals (e.g., SRS) received from the UE on one or more uplink receive beams. The positioning entity uses the signal strength measurements and the angles of the receive beams to determine the angle between the UE and the base station. Based on the determined angle and the known location of the base station, the positioning entity can then estimate the location of the UE.

[0081] Downlink and uplink-based positioning methods include extended cell ID (E-CID) positioning and multi-round trip time (RTT) positioning (also called "multi-cell RTT"). In the RTT procedure, an initiator (base station or UE) transmits an RTT measurement signal (e.g., PRS or SRS) to a responder (UE or base station), and the responder transmits an RTT response signal (e.g., SRS or PRS) back to the initiator. The RTT response signal includes the difference between the ToA of the RTT measurement signal and the transmission time of the RTT response signal, called the receive-to-transmit (Rx-Tx) time difference. The initiator calculates the difference between the transmission time of the RTT measurement signal and the ToA of the RTT response signal, called the transmit-to-receive (Tx-Rx) time difference. The propagation time (also called "time of flight") between the initiator and the responder can be calculated from the Tx-Rx time difference and the Rx-Tx time difference. Based on the propagation time and the known speed of light, the distance between the initiator and responder can be determined. For multi-RTT positioning, the UE performs RTT procedures with multiple base stations to allow the UE's location to be triangulated based on the known locations of the base stations. RTT and multi-RTT methods can be combined with other positioning techniques, such as UL-AoA and DL-AoD, to improve location accuracy.

[0082] The E-CID positioning method is based on radio resource management (RRM) measurements. In E-CID, the UE reports the serving cell ID, timing advance (TA), and the identities, estimated timing, and signal strength of detected neighboring base stations. The UE's location is then estimated based on this information and the known locations of the base stations.

[0083] To assist in positioning operations, a location server (e.g., location server 230, LMF 270, SLP 272) may provide assistance data to the UE. For example, the assistance data may include identifiers of base stations (or base station cells / TRPs) from which to measure reference signals, reference signal configuration parameters (e.g., number of consecutive positioning subframes, periodicity of positioning subframes, muting sequence, frequency hopping sequence, reference signal identifier, reference signal bandwidth, etc.), and / or other parameters applicable to a particular positioning method. Alternatively, the assistance data may originate directly from the base station itself (e.g., in periodically broadcast overhead messages, etc.), and in some cases, the UE may be able to detect neighboring network nodes itself without using the assistance data.

[0084] In the case of OTDOA or DL-TDOA positioning procedures, the assistance data may further include an expected RSTD value and an associated uncertainty around the expected RSTD, i.e., a search window. In some cases, the value range for the expected RSTD may be + / - 500 microseconds (μs). In some cases, when any of the resources used for positioning measurements are in FR1, the value range for the expected RSTD uncertainty may be + / - 32 μs. In other cases, when all of the resources used for positioning measurements are in FR2, the value range for the expected RSTD uncertainty may be + / - 8 μs.

[0085] A location estimate may be referred to by other names, such as a position estimate, location, position, position fix, fix, etc. A location estimate may be geodetic and comprise coordinates (e.g., latitude, longitude, and possibly altitude), or may be urban and comprise a street address, postal address, or some other linguistic description of the location. A location estimate may also be specified relative to some other known location or may be specified in absolute terms (e.g., using latitude, longitude, and possibly altitude). A location estimate may include an expected error or uncertainty (e.g., by including an area or volume that the location is expected to fall within, with some specified or default level of confidence).

[0086] There are various limitations to OTDOA-based positioning techniques. For example, GPS synchronization is limited to 50-100 nanoseconds (ns), limiting the GPS positioning used for the location of participating base stations to an accuracy of 15-30 meters (m). This level of accuracy is consistent with the 3GPP agreement for 50 ns synchronization. Due to GPS limitations, any tighter GPS synchronization would be more difficult and therefore less likely.

[0087] The above limitations on OTDOA-based positioning techniques have motivated the increased use of RTT-based positioning techniques. In NR, there may not be precise timing synchronization across the network. Instead, it may be sufficient to have coarse time synchronization across base stations (e.g., within the cyclic prefix (CP) duration of an Orthogonal Frequency Division Multiplexing (OFDM) symbol). RTT-based methods generally require only coarse timing synchronization and are therefore the preferred positioning method in NR.

[0088] 6 illustrates an example wireless communication system 600 according to an aspect of the present disclosure. In the example of FIG. 6, a UE 604 (e.g., any of the UEs described herein) is attempting to calculate an estimate of its location 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 location. The UE 604 may transmit and receive wireless signals to and from multiple base stations 602-1, 602-2, and 602-3 (labeled “BS”) (collectively, base stations 602, which may be any of the base stations described herein).

[0089] In a network-centric RTT positioning procedure, a serving base station 602 instructs a UE 604 to measure RTT measurement signals (e.g., PRS) from two or more neighboring base stations 602 (and the serving base station 602, since typically at least three base stations 602 are required for two-dimensional location estimation). The involved base stations 602 transmit the RTT measurement signals on small reuse resources (i.e., resources used by the base stations 602 to transmit system information) allocated by the network (e.g., location server 230, LMF 270, SLP 272). The UE 604 records the arrival time (also referred to as receive time, reception time, time of reception, or time of arrival) of each RTT measurement signal relative to the UE 604's current downlink timing (e.g., as derived by the UE 604 from downlink signals received from its serving base station 602) and transmits a common or individual RTT response signal (e.g., SRS) to the involved base station 602 on resources allocated by its serving base station. The UE 604 reports the UE's receive-to-transmit (Rx-Tx) time difference measurement to the positioning entity, if it is not one. The UE's Rx-Tx time difference measurement indicates the time difference between the arrival time of each RTT measurement signal at the UE 604 and the transmission time of the RTT response signal. Each participating base station 602 also reports a transmit-to-receive (Tx-Rx) time difference measurement to the positioning entity, indicating the difference between the time of transmission of the RTT measurement signal and the time of reception of the RTT response signal.

[0090] The UE-centric RTT positioning procedure is similar to the network-based procedure, except that the UE 604 transmits an uplink RTT measurement signal (e.g., on resources allocated by the serving base station 602). The uplink RTT measurement signal is measured by multiple base stations 602 in the vicinity of the UE 604. Each participating base station 602 responds with a downlink RTT response signal and reports the base station's Rx-Tx time difference measurement to the positioning entity. The base station's Rx-Tx time difference measurement indicates the time difference between the arrival time of the RTT measurement signal at the base station 602 and the transmission time of the RTT response signal. If the UE 604 is not the positioning entity, it reports a Tx-Rx time difference measurement for each base station 602, indicating the difference between the transmission time of the RTT measurement signal and the reception time of the RTT response signal.

[0091] To determine the location (x,y) of the UE 604, the positioning entity needs to know the locations of the base stations 602, which may be expressed in a reference coordinate system as (x_k,y_y), where k=1, 2, 3 in the example of Figure 6. If the UE 604 is the positioning entity, a location server (e.g., location server 230, LMF 270, SLP 272) with knowledge of the network geometry may provide the UE 604 with the locations of the involved base stations 602.

[0092] The positioning entity determines each distance 610 (d_k, where k=1, 2, 3) between the UE 604 and each base station 602 based on the Rx-Tx and Tx-Rx time difference measurements and the speed of light, as described further below with reference to Figure 7. Specifically, in the example of Figure 6, the distance 610-1 between the UE 604 and base station 602-1 is d_1, the distance 610-2 between the UE 604 and base station 602-2 is d_2, and the distance 610-3 between the UE 604 and base station 602-3 is d_3. Once each distance 610 is determined, the positioning entity can solve for the location (x, y) of the UE 604 by using various known geometric techniques, such as, for example, trilateration. From FIG. 6, it can be seen that the location of UE 604 is ideally at the common intersection of three semicircles, each defined by a radius dk and a center (x_k, y_k), where k=1, 2, 3.

[0093] FIG. 7 is a diagram 700 illustrating example timing of RTT measurement signals exchanged between a base station 702 (e.g., any of the base stations described herein) and a UE 704 (e.g., any of the UEs described herein) in accordance with an aspect of the disclosure. In the example of FIG. 7, the base station 702 (labeled "BS") sends an RTT measurement signal 710 (e.g., a PRS) to the UE 704 at time T_1. The RTT measurement signal 710 has some propagation delay T_Prop as it travels from the base station 702 to the UE 704. At time T_2 (the time of receipt of the RTT measurement signal 710 at the UE 704), the UE 704 measures the RTT measurement signal 710. After some UE processing time, the UE 704 transmits an RTT response signal 720 (e.g., an SRS) at time T_3. After a propagation delay T_Prop, the base station 702 measures the RTT response signal 720 from the UE 704 at time T_4 (the time of receipt of the RTT response signal 720 at the base station 702).

[0094] The UE 704 reports the difference between time T_3 and time T_2 (i.e., the UE's 704 Rx-Tx time difference measurement, shown as T_Rx-Tx 712) to the positioning entity. Similarly, the base station 702 reports the difference between time T_4 and time T_1 (i.e., the base station's 702 Tx-Rx time difference measurement, shown as T_Tx-Rx 722) to the positioning entity. Using these measurements and the known speed of light, the positioning entity can calculate the distance to the UE 704 as d=½*c*(T_Tx-Rx - T_Rx-Tx) = ½*c*(T_4 - T_1) - ½*c*(T_3 - T_2), where c is the speed of light.

[0095] Based on the known location of the base station 702 and the distance between the UE 704 and the base station 702 (and at least two other base stations 702), the positioning entity can calculate the location of the UE 704. As shown in Figure 6, the location of the UE 704 is at the common intersection of three semicircles, each defined by a radius of the distance between the UE 704 and a respective base station 702.

[0096] In one aspect, the positioning entity may calculate the location of the UE 604 / 704 using a two-dimensional coordinate system, although the aspects disclosed herein are not so limited and may also be applicable to determining location using a three-dimensional coordinate system if additional dimensions are desired. Additionally, while Figure 6 shows one UE 604 and three base stations 602 and Figure 7 shows one UE 704 and one base station 702, it will be appreciated that there may be many more UEs 604 / 704 and many more base stations 602 / 702.

[0097] FIG. 8 is a diagram 800 illustrating example timing of RTT measurement signals exchanged between a network node 802 and a UE 804 according to an aspect of the disclosure. Diagram 800 is similar to diagram 700, except that it includes processing delays that may occur at both the network node 802 and the UE 804 (labeled “Node”) when transmitting and receiving RTT measurement signals and RTT response signals. The network node 802 may be a base station (e.g., any of the base stations), a RIS (e.g., the RIS 410), another UE (e.g., any of the UEs described herein), or other network node capable of performing an RTT positioning procedure. As a specific example, the network node 802 and the UE 804 may correspond to the base station 702 and the UE 704 in FIG. 7. As another specific example, the network node 802 may correspond to the RIS 410 where the RIS 410 is a Mode 2 RIS.

[0098] Turning now to potential processing delays, at network node 802, there is a transmission delay 814 between time T_1 when the baseband of network node 802 (labeled "BB") generates an RTT measurement signal 810 (e.g., a PRS) and time T_2 when the antenna of network node 802 (labeled "Ant") transmits the RTT measurement signal 810. At UE 804, there is a reception delay 816 between time T_3 when the antenna of UE 604 (labeled "Ant") receives the RTT measurement signal 810 and time T_4 when the baseband of UE 804 (labeled "BB") processes the RTT measurement signal 810.

[0099] Similarly, for an RTT response signal 820 (e.g., an SRS), there is a transmission delay 826 between time T_5 when the baseband of the UE 804 generates the RTT response signal 820 and time T_6 when the antenna of the UE 804 transmits the RTT response signal 820. At the network node 802, there is a reception delay 824 between time T_7 when the antenna of the network node 802 receives the RTT response signal 820 and time T_8 when the baseband of the network node 802 processes the RTT response signal 820.

[0100] The difference between times T_2 and T_1 (i.e., transmit delay 814) and the difference between times T_8 and T_7 (i.e., receive delay 824) are referred to as the “group delay” of the network node 802. The difference between times T_4 and T_3 (i.e., receive delay 816) and the difference between times T_6 and T_5 (i.e., transmit delay 826) are referred to as the “group delay” of the UE 804. The group delay includes hardware group delay, software / firmware-induced group delay, or both. More specifically, although software and / or firmware may contribute to the group delay, the group delay is primarily due to internal hardware delays between the baseband and antennas of the network node 802 and the UE 804.

[0101] As shown in FIG. 8 , due to receive delay 816 and transmit delay 826, the Rx-Tx time difference measurement 812 of the UE 804 does not represent the difference between the actual receive time at time T_3 and the actual transmit time at time T_6. Similarly, due to transmit delay 814 and receive delay 824, the Tx-Rx time difference measurement 822 of the network node 802 does not represent the difference between the actual transmit time at time T_2 and the actual receive time at time T_7. Thus, as shown, group delays such as receive delays 814 and 816 and transmit delays 824 and 826 may contribute to timing and / or calibration errors that may affect RTT measurements and other measurements such as TDOA, RSTD, etc. This, in turn, may affect positioning performance. For example, in some designs, an error of 10 ns introduces an error of 3 meters in the final location estimate.

[0102] In some cases, the UE 804 may calibrate and compensate for its group delay so that the Rx-Tx time difference measurements 812 reflect the actual receive and transmit times from its antennas. Alternatively, the UE 804 may report its group delay to a positioning entity (if not the UE 804), which may then subtract the group delay from the Rx-Tx time difference measurements 812 when determining the final distance between the network node 802 and the UE 804. Similarly, the network node 802 may be able to compensate for its group delay in the Tx-Rx time difference measurements 822, or may simply report the group delay to the positioning entity.

[0103] In some cases, a UE may not be able to detect and measure a PRS transmitted by a non-serving (e.g., neighboring) base station (e.g., an RTT measurement signal transmitted by a neighboring base station 602), especially for base stations that are far away from the UE. This can be a particular problem for low-tier UEs, also known as reduced-capability NR UEs, "NR RedCap" UEs, reduced-capability UEs, NR lightweight UEs, lightweight UEs, NR ultra-light UEs, or ultra-light UEs. Low-tier UEs are in contrast to premium UEs, which may alternatively be referred to as full-capability UEs or simply UEs. Low-tier UEs generally have lower baseband processing capabilities, fewer antennas (e.g., one receiver antenna as a baseline in FR1 or FR2, optionally two receiver antennas), lower operating bandwidth capabilities (e.g., 20 MHz for FR1 without additional uplink or carrier aggregation, or 50 or 100 MHz for FR2), half-duplex-only frequency division duplex (HD-FDD) capabilities, smaller HARQ buffers, reduced physical downlink control channel (PDCCH) monitoring, constrained modulation (e.g., 64QAM for the downlink and 16QAM for the uplink), relaxed processing timeline requirements, and / or lower uplink transmit power compared to premium UEs. Different UE tiers may be distinguished by UE category and / or UE capabilities. For example, some types of UEs may be assigned a classification of “low tier” (e.g., by original equipment manufacturer (OEM), applicable wireless communications standard, etc.), and other types of UEs may be assigned a classification of “premium.” UEs of some tiers may also report their type (e.g., "low tier" or "premium") to the network. Additionally, some resources and / or channels may be dedicated to some types of UEs.

[0104] Similar to measuring downlink PRS from distant base stations, measurements of uplink positioning reference signals (e.g., SRS) by distant non-serving base stations may be poor. Again, this may be particularly problematic for SRS transmitted by low-tier UEs, given their reduced transmit power. Therefore, the present disclosure provides techniques for improving the quality of PRS and / or SRS measurements involving non-serving base stations using RIS-based transmission and reception, which may improve RTT-based positioning. However, as explained above, different RISs may have different capabilities and / or operating modes (e.g., Mode 1, Mode 2) that need to be taken into account in a RIS-assisted RTT positioning system.

[0105] The first technique described herein relates to RIS operation mode / capability reporting for RTT-based positioning. One or more RISs (e.g., RIS 410) may be controlled by one or more base stations (e.g., base station 402). During the initial setup stage of a RIS-assisted positioning session, each base station may report the operation mode of its associated RIS to a location server (e.g., location server 230, LMF 270, SLP 272) or other positioning entity (e.g., a UE for UE-based positioning). The report should indicate the RIS operation mode (i.e., Mode 1 or Mode 2) of each RIS. For Mode 2 RISs, due to the higher processing capabilities of Mode 2 RISs, the Mode 2 RIS may be able to calculate Tx-Rx time difference measurements and report the Tx-Rx time difference measurements to its controlling base station. Therefore, for Mode 2 RISs, the report may also indicate, for each Mode 2 RIS, whether the Mode 2 RIS is able to calculate and report Tx-Rx time difference measurements. Alternatively, the Mode 2 RIS may not be able to calculate and / or report its Tx-Rx time difference measurement, but another entity (e.g., a controlling base station) may be able to calculate the group delay (similar to the group delay of the base station 802 and UE 804 in FIG. 8) for the Mode 2 RIS. In this case, the report may indicate that the group delay for the Mode 2 RIS can be reported, or may indicate the actual group delay measurement.

[0106] However, in some cases, a Mode 2 RIS may not be able to calculate and / or report Tx-Rx time difference measurements, and other entities (e.g., the controlling base station) may not be able to determine the group delay of the RIS. In this case, the controlling base station should report the RIS as being unable to calculate and report Tx-Rx time difference measurements, or that Tx-Rx time difference measurements cannot be obtained. This indicates that the particular RIS cannot support RTT-based positioning.

[0107] Alternatively, if a Mode 2 RIS is not capable of calculating and reporting Tx-Rx time difference measurements, but its group delay (as reported by another entity, such as a controlling base station) is less than or equal to "x" ns (where "x" is some small value, such as "2"), it may still be able to support RTT-based positioning. As a first option, the controlling base station may report the maximum group delay of the RIS. As a second option, the controlling base station may report the mean, variance, or average of the group delay of the RIS. As yet another option, the group delay of the RIS may be pre-measured and / or calibrated, so that the actual group delay can be used for positioning (and need not be less than "x").

[0108] Different RIS operation modes and reported capabilities create the need for different RTT positioning procedures. Figure 9 is a diagram 900 of a first type of RTT positioning procedure between a base station 902 (e.g., any of the base stations described herein), a UE 904 (e.g., any of the UEs described herein), and a RIS 906 (e.g., RIS 410) in accordance with an aspect of the present disclosure. The base station 902 may be a controlling base station for the RIS 906 (or one of them). The base station 902 may be a serving base station 902 for the UE 904 or a neighbor base station 902.

[0109] The RTT positioning procedure shown in Figure 9 may be performed when the RIS 906 is in mode 1 (i.e., operating as a reconfigurable mirror / reflector), or when the RIS is in mode 2 and cannot calculate and report Tx-Rx time difference measurements but its group delay is less than some threshold number of nanoseconds (e.g., "x" ns, where "x" is some small number such as "1") or has been previously measured / calibrated. When these conditions are met in the operation of the RIS 906, the base station 902, the RIS 906, and the UE 904 can perform the RTT positioning procedure shown in Figure 9. The positioning entity (e.g., the UE 904 or a location server) can incorporate the threshold number of nanoseconds (e.g., "x" ns) or the previously measured / calibrated group delay into its positioning uncertainty estimate.

[0110] As shown in FIG. 9 , base station 902 transmits an RTT measurement signal 910 (e.g., a PRS) to RIS 906 at time T_1. The RTT measurement signal 910 has some propagation delay "T_Prop1" as it travels from base station 902 to RIS 906 and arrives at RIS 906 at time T_2. At time T_3, RIS 906 reflects the RTT measurement signal 910 toward UE 904. The difference between time T_3 and time T_2 is the group delay of RIS 906. If RIS 906 is a Mode 1 RIS, the difference between time T_3 and time T_2 is assumed to be negligible. If RIS 906 is a Mode 2 RIS, the difference between time T_3 and time T_2 should be less than a threshold in nanoseconds or known from a previous calibration, as explained above.

[0111] The RTT measurement signal 910 has some propagation delay "T_Prop2" as it travels from the RIS 906 to the UE 904, and the UE 904 measures the RTT measurement signal 910 at time T_4. After some UE processing time, the UE 904 transmits an RTT response signal 920 (e.g., an SRS) towards the RIS 906 at time T_5. The difference between T_5 and T_4 is the UE 904's Rx-Tx time difference measurement 912 and is reported to the positioning entity (if not the UE 904). After propagation delay T_Prop2, the RTT response signal 920 reaches the RIS 906 at time T_6. At time T_7, the RIS 906 reflects the RTT response signal 920 towards the base station 902. The difference between time T_7 and time T_6 is the RIS 906's group delay. After a propagation delay T_Prop1, the base station 902 measures an RTT response signal 920 from the UE 904 at time T_8. The difference between time T_8 and time T_1 is the Tx-Rx time difference measurement 922 of the base station 902 and is reported to the positioning entity.

[0112] Based on the Rx-Tx time difference measurement 912 and the Tx-Rx time difference measurement 922, the positioning entity determines the distance (d) between the RIS 906 and the UE 904.

[0113]

number

[0114] It can be calculated as:

[0115] In the above equation, c is the speed of light and d BS_RISis the distance between the base station 902 and the RIS 906. The distance between the base station 902 and the RIS 906 is known by a location server and may be provided to the UE 904 for UE-based positioning. Alternatively, this distance may be estimated through a RAT-based positioning technique (e.g., RTT) or a RAT-independent technique (e.g., GPS). As can be appreciated, the final distance estimation removes the distance between the base station 902 and the RIS 906. Based on the calculated distance and the known locations of the base station 902 and the RIS 906, as well as the distance between the UE 904 and at least two other base stations or RISs with known locations, the positioning entity can estimate the location of the UE 904 as described above.

[0116] 10 is a diagram 1000 of a second type of RTT positioning procedure between a base station 1002 (e.g., any of the base stations described herein), a UE 1004 (e.g., any of the UEs described herein), and a RIS 1006 (e.g., RIS 410) in accordance with an aspect of the present disclosure. The base station 1002 may be a controlling base station (or one of them) for the RIS 1006. The base station 1002 may be a serving base station 1002 for the UE 1004 or a neighbor base station 1002. The RTT positioning procedure shown in FIG. 10 may be performed when the RIS 1006 is in mode 2 and is able to calculate and report Tx-Rx time difference measurements to the controlling base station 1002.

[0117] 10 , the base station 1002 transmits an RTT measurement signal 1010 (e.g., a PRS) to the RIS 1006 at time T_1. The RTT measurement signal 1010 has some propagation delay “T_Prop1” as it travels from the base station 1002 to the RIS 1006 and arrives at the RIS 1006 at time T_2. At time T_3, the RIS 1006 reflects the RTT measurement signal 1010 back to the UE 1004. The difference between time T_3 and time T_2 may be the group delay (e.g., transmission delay 814) of the RIS 1006, or the group delay may be configured by the controlling base station 1002.

[0118] The RTT measurement signal 1010 has some propagation delay "T_Prop2" as it travels from the RIS 1006 to the UE 1004, and the UE 1004 measures the RTT measurement signal 1010 at time T_4. After some UE processing time, the UE 1004 transmits an RTT response signal 1020 (e.g., SRS) towards the RIS 1006 at time T_5. The difference between T_5 and T_4 is the UE 1004's Rx-Tx time difference measurement 1012 and is reported to the positioning entity (if not the UE 1004). After propagation delay T_Prop2, the RTT response signal 1020 reaches the RIS 1006 at time T_6. At time T_7, the RIS 1006 reflects the RTT response signal 1020 towards the base station 1002. The difference between time T_7 and time T_6 may be the group delay (e.g., receive delay 824) of the RIS 1006, or the group delay may be configured by the controlling base station 1002. After a propagation delay T_Prop1, the base station 1002 measures the RTT response signal 1020 from the UE 1004 at time T_8.

[0119] 10 RIS 1006 is a Mode 2 RIS that can calculate and report the Tx-Rx time difference measurement 1022. Thus, at some point after time T_6, the RIS 1006 reports the Tx-Rx time difference measurement 1022 to the base station 1002 (for forwarding to the positioning entity) or directly to the positioning entity (if possible). The base station 1002 does not need to report its Tx-Rx time difference measurement (i.e., the difference between time T_8 and time T_1) to the positioning entity.

[0120] Based on the Rx-Tx time difference measurement 1012 and the Tx-Rx time difference measurement 1022, the positioning entity determines the distance (d) between the RIS 1006 and the UE 1004 as

[0121]

number

[0122] It can be calculated as:

[0123] In the above equation, c is the speed of light. Based on the calculated distance and the known location of the RIS 1006, as well as the distance between the UE 1004 and at least two other base stations or RISs with known locations, the positioning entity can estimate the location of the UE 1004 as described above. Note that the location of the base station 1002 is not required.

[0124] 10 , the base station 1002 may report times T_2, T_3, T_6, and T_7 to the positioning entity, or may report the time difference between T_3 and T_2 and the time difference between T_7 and T_6. In that case, the positioning entity can use the time difference between times T_8 and T_1 (i.e., the Tx-Rx time difference measurement of the base station 1002) rather than the Tx-Rx time difference measurement 1022 of the RIS 1006 to calculate the distance between the base station 1002 and the UE 1004. The positioning entity can calculate the distance between the base station 1002 and the UE 1004 using the formula described above with reference to FIG. 9 in addition to subtracting the time differences between T_3 and T_2 and the time differences between T_7 and T_6 from the Tx-Rx time difference measurement of the base station 1002.

[0125] 11 illustrates an example method 1100 of positioning according to an aspect of the disclosure. In one aspect, method 1100 may be performed by a positioning entity. The positioning entity may be a UE (e.g., any of the UEs described herein), a component of a RAN (e.g., a base station or other RAN entity), or a location server (e.g., location server 230, LMF 270, SLP 272).

[0126] At 1110, the positioning entity receives a report indicating an operational mode of a RIS (e.g., RIS 410) associated with at least one base station (e.g., any of the base stations described herein). In one aspect, if the positioning entity is a UE, operation 1110 may be performed by WWAN transceiver 310, processing system 332, memory component 340, and / or positioning component 342, any or all of which may be considered means for performing this operation. If the positioning entity is a base station or other RAN entity, operation 1110 may be performed by WWAN transceiver 350, network interface 380, processing system 384, memory component 386, and / or positioning component 388, any or all of which may be considered means for performing this operation. If the positioning entity is a location server, operation 1110 may be performed by network interface 390, processing system 394, memory component 396, and / or positioning component 398, any or all of which may be considered a means for performing this operation.

[0127] At 1120, the positioning entity receives Tx-Rx time difference measurements for a network node (e.g., a RIS or at least one base station) involved in an RTT positioning session with the UE (e.g., any of the UEs described herein). In one aspect, if the positioning entity is a UE, operation 1120 may be performed by WWAN transceiver 310, processing system 332, memory component 340, and / or positioning component 342, any or all of which may be considered means for performing this operation. If the positioning entity is a base station or other RAN entity, operation 1120 may be performed by WWAN transceiver 350, network interface 380, processing system 384, memory component 386, and / or positioning component 388, any or all of which may be considered means for performing this operation. If the positioning entity is a location server, operation 1120 may be performed by network interface 390, processing system 394, memory component 396, and / or positioning component 398, any or all of which may be considered a means for performing this operation.

[0128] At 1130, the positioning entity determines an Rx-Tx time difference measurement for the UE, where the Rx-Tx time difference measurement represents the difference between the reception time at the UE of a downlink positioning reference signal from the RIS and the transmission time from the UE of an uplink positioning reference signal toward the RIS. In one aspect, if the positioning entity is a UE, operation 1130 may be performed by WWAN transceiver 310, processing system 332, memory component 340, and / or positioning component 342, any or all of which may be considered means for performing this operation. If the positioning entity is a base station or other RAN entity, operation 1130 may be performed by WWAN transceiver 350, network interface 380, processing system 384, memory component 386, and / or positioning component 388, any or all of which may be considered means for performing this operation. If the positioning entity is a location server, operation 1130 may be performed by network interface 390, processing system 394, memory component 396, and / or positioning component 398, any or all of which may be considered a means for performing this operation.

[0129] At 1140, the positioning entity calculates a distance between the UE and the RIS based at least in part on the Tx-Rx time difference measurement and the Rx-Tx time difference measurement. In one aspect, if the positioning entity is a UE, operation 1140 may be performed by WWAN transceiver 310, processing system 332, memory component 340, and / or positioning component 342, any or all of which may be considered a means for performing this operation. If the positioning entity is a base station or other RAN entity, operation 1140 may be performed by WWAN transceiver 350, network interface 380, processing system 384, memory component 386, and / or positioning component 388, any or all of which may be considered a means for performing this operation. If the positioning entity is a location server, operation 1140 may be performed by network interface 390, processing system 394, memory component 396, and / or positioning component 398, any or all of which may be considered a means for performing this operation.

[0130] As will be appreciated, a technical advantage of method 1100 is improved PRS and SRS reception at the UE and base stations (especially at more distant base stations), respectively, thereby improving positioning performance.

[0131] In the above detailed description, it can be seen that various features are grouped together in the examples. This manner of disclosure should not be understood as an intention that the example clauses have more features than are expressly recited in each clause. Rather, various aspects of the present disclosure may include fewer than all features of each example clause disclosed. Accordingly, the following clauses are hereby considered to be incorporated into this description, and each clause may stand alone as a separate example. Although each dependent clause may refer to a specific combination with one of the other clauses within that clause, the aspects of that dependent clause are not limited to that specific combination. It will be appreciated that other example clauses can also include combinations of aspects of that dependent clause with the subject matter of any other dependent clause or independent clause, or combinations of any features with other dependent clauses and independent clauses. The various aspects disclosed herein expressly include combinations of these combinations unless a particular combination is expressly expressed or can be readily inferred (e.g., contradictory aspects, such as defining an element as both an insulator and a conductor). It is further contemplated that aspects of a clause may be included within any other independent clause, even if the clause is not directly dependent on the independent clause.

[0132] Example implementations are described in the following numbered clauses.

[0133] Clause 1. A method of positioning performed by a positioning entity, comprising: receiving a report indicating an operating mode of a reconfigurable intelligent surface (RIS) associated with at least one base station; receiving a transmit-to-receive (Tx-Rx) time difference measurement for a network node involved in a round-trip time (RTT) positioning session with a user equipment (UE); determining a receive-to-receive (Rx-Tx) time difference measurement for the UE, wherein the Rx-Tx time difference measurement represents a difference between a reception time at the UE of a downlink positioning reference signal from the RIS and a transmission time from the UE of an uplink positioning reference signal towards the RIS; and calculating a distance between the UE and the RIS based at least in part on the Tx-Rx time difference measurement and the Rx-Tx time difference measurement.

[0134] Clause 2. The method of clause 1, wherein the mode of operation of the RIS indicates that the RIS is operated as a reconfigurable reflector.

[0135] Clause 3. The method of clause 2, wherein the RIS is operated as a reconfigurable reflector, and the reporting does not include the group delay of the RIS.

[0136] Clause 4. The method of any of clauses 2-3, wherein the network node is at least one base station, the Tx-Rx time difference measurement represents a time difference between a transmission time from the at least one base station of a downlink positioning reference signal towards the RIS and a reception time at the at least one base station of an uplink positioning reference signal from the RIS, and calculating a distance between the UE and the RIS comprises subtracting a distance between the at least one base station and the RIS from a distance calculated based at least in part on the Tx-Rx time difference measurement and the Rx-Tx time difference measurement.

[0137] Clause 5. The method of clause 1, wherein the operation mode of the RIS indicates that the RIS is operated as a relay node.

[0138] Clause 6. The method of clause 5, wherein the reporting further includes an indication that a Tx-Rx time difference at the RIS is not calculated and reported, the Tx-Rx time difference at the RIS representing the time difference between the transmission time from the RIS of a downlink positioning reference signal towards the UE and the reception time at the RIS of an uplink positioning reference signal from the UE.

[0139] Clause 7. The method of clause 6, wherein the reporting further includes group delays of the RIS.

[0140] Clause 8. The method of clause 7, wherein the group delay is included in the report as the mean RIS group delay, the typical RIS group delay, the variance of the RIS group delay, the maximum RIS group delay, the previously calibrated RIS group delay, or any combination thereof.

[0141] Clause 9. The method of any of clauses 7-8, wherein the group delay is less than a time threshold.

[0142] Clause 10. The method of clause 9, wherein the network node is at least one base station, and the Tx-Rx time difference measurement represents a time difference between a transmission time from the at least one base station of a downlink positioning reference signal towards the RIS and a reception time at the at least one base station of an uplink positioning reference signal from the RIS, and calculating a distance between the UE and the RIS comprises subtracting a distance between the at least one base station and the RIS from a distance calculated based at least in part on the Tx-Rx time difference measurement and the Rx-Tx time difference measurement.

[0143] Clause 11. The method of clause 10, wherein the distance between the UE and the RIS is:

[0144]

number

[0145] where c is the speed of light and T Rx-Txis the Rx-Tx time difference measurement, and T Tx-Rx is the Tx-Rx time difference measurement, and d BS_RIS is the distance between at least one base station and the RIS.

[0146] Clause 12. The method of any of clauses 10-11, further comprising calculating an uncertainty value for the distance between the UE and the RIS based at least in part on a time threshold.

[0147] Clause 13. The method of any of clauses 5-12, wherein the reporting further includes an indication that the RIS is capable of calculating and reporting a RIS Tx-Rx time difference measurement representing the time difference between the transmission time from the RIS of a downlink positioning reference signal towards the UE and the reception time at the RIS of an uplink positioning reference signal from the UE.

[0148] Clause 14. The method of clause 13, wherein the network node is a RIS, and the Tx-Rx time difference measurement represents the time difference between the transmission time from the RIS of a downlink positioning reference signal towards the UE and the reception time at the RIS of an uplink positioning reference signal from the UE.

[0149] Clause 15. The method of clause 14, wherein the distance between the UE and the RIS is:

[0150]

number

[0151] where c is the speed of light and T Rx-Tx is the Rx-Tx time difference measurement, and T Tx-Rx is the Tx-Rx time difference measurement.

[0152] Clause 16. The method of any of clauses 5 to 15, further comprising receiving a first time difference measurement between a reception time at the RIS of a downlink positioning reference signal from the at least one base station and a transmission time from the RIS of a downlink positioning reference signal towards the UE, and receiving a second time difference measurement between a reception time at the RIS of an uplink positioning reference signal from the UE and a transmission time from the RIS of an uplink positioning reference signal towards the at least one base station.

[0153] Clause 17. The method of clause 16, wherein the network node is at least one base station, and the Tx-Rx time difference measurement represents a time difference between a transmission time from the at least one base station of a downlink positioning reference signal towards the RIS and a reception time at the at least one base station of an uplink positioning reference signal from the RIS, and calculating a distance between the UE and the RIS comprises subtracting the first time difference measurement and the second time difference measurement from the Tx-Rx time difference measurement, and subtracting a distance between the at least one base station and the RIS from a distance calculated based at least in part on the Tx-Rx time difference measurement and the Rx-Tx time difference measurement.

[0154] Clause 18. The method of any of clauses 16-17, wherein the first time difference measurement and the second time difference measurement are configured by at least one base station.

[0155] Clause 19. The method of any of clauses 1-18, wherein the Tx-Rx time difference measurements are received from at least one base station.

[0156] Clause 20. The method of any of clauses 1 to 19, wherein the positioning entity is a location server, and determining the Rx-Tx time difference measurement value comprises receiving the Rx-Tx time difference measurement value from the UE.

[0157] Clause 21. The method of any of clauses 1 to 19, wherein the positioning entity is a UE.

[0158] Clause 22. The method of any of clauses 1 to 21, wherein at least one base station is a neighboring base station of the UE.

[0159] Clause 23. An apparatus comprising a memory, at least one transceiver, and at least one processor communicatively coupled to the memory and the at least one transceiver, wherein the at least one processor is configured to perform a method according to any of clauses 1 to 22.

[0160] Clause 24. Apparatus comprising means for carrying out the method according to any of clauses 1 to 22.

[0161] Clause 25. A computer-readable medium storing computer-executable instructions, the computer-executable instructions comprising at least one instruction for causing an apparatus to perform a method according to any of clauses 1 to 22.

[0162] Clause 23. An apparatus comprising a memory and at least one processor communicatively coupled to the memory, wherein the memory and the at least one processor are configured to perform a method according to any of clauses 1 to 22.

[0163] Clause 24. Apparatus comprising means for carrying out the method according to any of clauses 1 to 22.

[0164] Clause 25. A non-transitory computer-readable medium storing computer-executable instructions, the computer-executable instructions comprising at least one instruction for causing a computer or processor to perform a method according to any of clauses 1 to 22.

[0165] Those skilled in the art will appreciate that information and signals may be represented using any of a variety of different technologies and techniques. For example, the data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0166] Furthermore, those skilled in the art will appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the aspects disclosed herein may be implemented as electronic hardware, computer software, or a combination of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the particular application and design constraints imposed on the overall system. Those skilled in the art may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.

[0167] The various illustrative logic blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented or performed using a general-purpose processor, a digital signal processor (DSP), an ASIC, a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but alternatively, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0168] The methods, sequences, and / or algorithms described in connection with the aspects disclosed herein may be embodied directly in hardware, in software modules executed by a processor, or in a combination of the two. The software modules may reside in random access memory (RAM), flash memory, read-only memory (ROM), erasable programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. Alternatively, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal (e.g., UE). Alternatively, the processor and the storage medium may reside as discrete components in the user terminal.

[0169] In one or more exemplary aspects, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media, including any medium that facilitates transfer of a computer program from one place to another. Storage media may be any available medium that can be accessed by a computer. By way of example, and not limitation, such computer-readable media may comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection is properly termed a computer-readable medium. For example, if software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included within the definition of medium. Disk and disc, as used herein, include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs, where disks typically reproduce data magnetically and discs reproduce data optically using lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0170] While the above disclosure illustrates exemplary aspects of the present disclosure, it should be noted that various changes and modifications can be made herein without departing from the scope of the present disclosure as defined by the appended claims. The functions, steps, and / or actions of the method claims in accordance with the aspects of the present disclosure described herein need not be performed in any particular order. Furthermore, although elements of the present disclosure may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated. [Explanation of symbols]

[0171] 100 Wireless Communication System 102 Base station (BS) 104 User Equipment (UE) 110 Coverage Area 112 Space Vehicle (SV) 120 Communication Links 122 backhaul links 124 SPS signals 134 backhaul links 150 Wireless Local Area Network (WLAN) Access Points (APs) 152 Wireless Local Area Network (WLAN) Station (STA) 154 communication links 164 User Equipment (UE) 170 Core Network 172 Location Server 180 mmW base station 182 User Equipment (UE) 184 Millimeter Wave (mmW) Communication Link 190 User Equipment (UE) 192, 194 Device-to-Device (D2D) Peer-to-Peer (P2P) Links 200 Wireless Network Structure 204 User Equipment (UE) 210 5G Core (5GC) 212 User Plane Functions 213 User Plane Interface (NG-U) 214 Control Plane Functions 215 Control Plane Interface (NG-C) 220 Next Generation RAN (NG-RAN) 222 gNB 223 Backhaul Connection 224 ng-eNB 230 Location Server 250 Wireless Network Structure 260 5G Core (5GC) 262 User Plane Function (UPF) 263 User Plane Interface 264 Access and Mobility Management Function (AMF) 265 Control Plane Interface 266 Session Management Facility (SMF) 270 Location Management Function (LMF) 272 Secure User Plane Location (SUPL) Location Platform (SLP) 302 User Equipment (UE) 304 Base Station (BS) 306 Network Entity 310 Wireless Wide Area Network (WWAN) Transceiver 312 Receiver 314 Transmitter 316 Antenna 318 Signal 320 Short-Range Wireless Transceiver 322 Receiver 324 Transmitter 326 Antenna 328 signal 330 Satellite Positioning System (SPS) Receiver 332 Processing System 334 Data Bus 336 Antenna 338 Satellite Positioning System (SPS) signals 340 Memory Components 342 Positioning Components 344 Sensors 346 User Interface 350 Wireless Wide Area Network (WWAN) Transceiver 352 receiver 354 Transmitter 356 Antenna 358 Signal 360 Short Range Wireless Transceiver 362 Receiver 364 Transmitter 366 Antenna 368 signal 370 Satellite Positioning System (SPS) Receiver 376 Antenna 378 Satellite Positioning System (SPS) Signals 380 Network Interface 382 Data Bus 384 Processing Systems 386 Memory Components 388 Positioning Components 390 Network Interface 392 Data Bus 394 Processing Systems 396 Memory Components 398 Positioning Components 400 System 402-1 First base station 402-2 Second base station 404 User Equipment (UE) 404-1 First UE 404-2 Second UE 410 Reconfigurable Intelligent Surface (RIS) 420 Obstacles 500 RIS 510 Flat surface 512 Reflective Elements 514 PIN diode 516 bias wire 520 Controller 600 Wireless Communication System 602 base station, serving base station, neighboring base station 604 User Equipment (UE) 610 distance 702 base station 704 User Equipment (UE) 710 RTT measurement signal 720 RTT response signal 802 Network Node 804 User Equipment (UE) 810 RTT measurement signal 812 Rx-Tx time difference measurement 814 Transmission Delay 816 Reception Delay 820 RTT response signal 822 Tx-Rx time difference measurement 824 Reception Delay 826 Transmission Delay 902 base station, serving base station, neighboring base station 904 User Equipment (UE) 906 RIS 910 RTT measurement signal 912 Rx-Tx time difference measurement 920 RTT response signal 922 Tx-Rx time difference measurement 1002 base station, serving base station, neighboring base station, control base station 1004 User Equipment (UE) 1006 RIS 1010 RTT measurement signal 1012 Rx-Tx time difference measurement 1020 RTT response signal 1022 Tx-Rx time difference measurements

Claims

1. 1. A method of positioning performed by a positioning entity, comprising: receiving a report indicating an operational mode of a reconfigurable intelligent surface (RIS) associated with at least one base station; the indicated mode of operation is one of a plurality of modes of operation of the RIS, including a first mode in which the RIS is operated as a reconfigurable reflector and a second mode in which the RIS is operated as a relay node; the indicated mode of operation of the report is the operation of the RIS as a relay node; the reporting further includes an indication that the RIS is capable of calculating and reporting a RIS transmit-to-receive (Tx-Rx) time difference measurement representing the time difference between a transmission time (T_3) from the RIS of a downlink positioning reference signal towards a user equipment (UE) and a reception time (T_6) at the RIS of an uplink positioning reference signal from the UE; receiving a transmit-to-receive (Tx-Rx) time difference measurement for the RIS representing the difference in time between a transmission time (T_3) from the RIS of a downlink positioning reference signal towards the UE and a reception time (T_6) at the RIS of an uplink positioning reference signal from the UE; determining a receive-to-transmit (Rx-Tx) time difference measurement for the UE; the Rx-Tx time difference measurement represents the difference in time between a reception time (T_4) at the UE of a downlink positioning reference signal from the RIS and a transmission time (T_5) from the UE of an uplink positioning reference signal towards the RIS; calculating a distance between the UE and the RIS based at least in part on the Tx-Rx time difference measurement for the RIS and the Rx-Tx time difference measurement for the UE based on the indicated mode of operation of the RIS in the report being the operation of the RIS as a relay node; A method for providing the above.

2. 1. A method of positioning performed by a positioning entity, comprising: receiving a report indicating an operational mode of a reconfigurable intelligent surface (RIS) associated with at least one base station; the indicated mode of operation is one of a plurality of modes of operation of the RIS, including a first mode in which the RIS is operated as a reconfigurable reflector and a second mode in which the RIS is operated as a relay node; the indicated mode of operation in the report is the operation of the RIS as a relay node; receiving a transmit-to-receive (Tx-Rx) time difference measurement for said at least one base station representing the difference in time between a transmission time (T_1) from said at least one base station of a downlink positioning reference signal towards said RIS and a reception time (T_8) at said at least one base station of an uplink positioning reference signal from said RIS; determining a receive-to-transmit (Rx-Tx) time difference measurement for a user equipment (UE), the Rx-Tx time difference measurement represents the difference in time between a reception time (T_4) at the UE of a downlink positioning reference signal from the RIS and a transmission time (T_5) from the UE of an uplink positioning reference signal towards the RIS; receiving a first time difference measurement between a reception time (T_2) at the RIS of the downlink positioning reference signal from the at least one base station and a transmission time (T_3) from the RIS of the downlink positioning reference signal towards the UE; receiving a second time difference measurement between a reception time (T_6) at the RIS of the uplink positioning reference signal from the UE and a transmission time (T_7) from the RIS of the uplink positioning reference signal towards the at least one base station; calculating a distance between the UE and the RIS by subtracting the first time difference measurement and the second time difference measurement from the Tx-Rx time difference measurement, and subtracting a distance between the at least one base station and the RIS from a distance calculated based at least in part on the Tx-Rx time difference measurement and the Rx-Tx time difference measurement, based on the indicated operation mode of the report being the operation of the RIS as a relay node; A method for providing the above.

3. The method of claim 2 , wherein the first time difference measurement and the second time difference measurement are configured by the at least one base station.

4. The method of claim 1 or 2, wherein the Tx-Rx time difference measurements are received from the at least one base station.

5. the positioning entity is a location server; determining the Rx-Tx time difference measurement comprises: The method of claim 1 or 2, comprising receiving the Rx-Tx time difference measurement from the UE.

6. The method of claim 1 or 2, wherein the positioning entity is the UE.

7. The method according to claim 1 or 2, wherein the at least one base station is a neighboring base station of the UE.

8. A positioning entity, comprising: at least one memory; at least one transceiver; at least one processor communicatively coupled to the memory and the at least one transceiver; wherein the at least one processor: receiving, via the at least one transceiver, a report indicating an operational mode of a reconfigurable intelligent surface (RIS) associated with at least one base station; the indicated mode of operation is one of a plurality of modes of operation of the RIS, including a first mode in which the RIS is operated as a reconfigurable reflector and a second mode in which the RIS is operated as a relay node; the indicated mode of operation of the report is the operation of the RIS as a relay node; receiving, the report further including an indication that the RIS is capable of calculating and reporting a RIS transmit-to-receive (Tx-Rx) time difference measurement representing the time difference between a transmission time (T_3) from the RIS of a downlink positioning reference signal towards a user equipment (UE) and a reception time (T_6) at the RIS of an uplink positioning reference signal from the UE; receiving, via the at least one transceiver, a transmit-to-receive (Tx-Rx) time difference measurement for the RIS representing a difference in time between a transmission time (T_3) from the RIS of a downlink positioning reference signal towards the UE and a reception time (T_6) at the RIS of an uplink positioning reference signal from the UE; determining a receive-to-transmit (Rx-Tx) time difference measurement for the UE; determining that the Rx-Tx time difference measurement represents a difference in time between a reception time at the UE of a downlink positioning reference signal from the RIS (T_4) and a transmission time from the UE of an uplink positioning reference signal towards the RIS (T_5); calculating a distance between the UE and the RIS based at least in part on the Tx-Rx time difference measurement for the RIS and the Rx-Tx time difference measurement for the UE based on the indicated operation mode of the report being the operation of the RIS as a relay node; a positioning entity configured to:

9. A positioning entity, comprising: at least one memory; at least one transceiver; at least one processor communicatively coupled to the memory and the at least one transceiver; wherein the at least one processor: receiving, via the at least one transceiver, a report indicating an operational mode of a reconfigurable intelligent surface (RIS) associated with at least one base station; the indicated mode of operation is one of a plurality of modes of operation of the RIS, including a first mode in which the RIS is operated as a reconfigurable reflector and a second mode in which the RIS is operated as a relay node; receiving the report, wherein the indicated mode of operation of the RIS is the operation of the RIS as a relay node; receiving, via the at least one transceiver, a transmit-to-receive (Tx-Rx) time difference measurement for the at least one base station representing a difference in time between a transmission time (T_1) from the at least one base station of a downlink positioning reference signal towards the RIS and a reception time (T_8) at the at least one base station of an uplink positioning reference signal from the RIS; determining a receive-to-transmit (Rx-Tx) time difference measurement for a user equipment (UE), determining that the Rx-Tx time difference measurement represents a difference in time between a reception time (T_4) at the UE of a downlink positioning reference signal from the RIS and a transmission time (T_5) from the UE of an uplink positioning reference signal towards the RIS; receiving a first time difference measurement between a reception time (T_2) at the RIS of the downlink positioning reference signal from the at least one base station and a transmission time (T_3) from the RIS of the downlink positioning reference signal towards the UE; receiving a second time difference measurement between a reception time (T_6) at the RIS of the uplink positioning reference signal from the UE and a transmission time (T_7) from the RIS of the uplink positioning reference signal towards the at least one base station; calculating a distance between the UE and the RIS by subtracting the first time difference measurement and the second time difference measurement from the Tx-Rx time difference measurement based on the indicated operation mode of the report being the operation of the RIS as a relay node, and subtracting a distance between the at least one base station and the RIS from a distance calculated based at least in part on the Tx-Rx time difference measurement and the Rx-Tx time difference measurement; a positioning entity configured to:

10. The positioning entity of claim 9 , wherein the first time difference measurement and the second time difference measurement are configured by the at least one base station.

11. 10. The positioning entity of claim 8 or 9, wherein the Tx-Rx time difference measurements are received from the at least one base station.

12. the positioning entity is a location server; The at least one processor is configured to determine the Rx-Tx time difference measurement, 10. The positioning entity of claim 8 or 9, configured to receive the Rx-Tx time difference measurement from the UE.

13. The positioning entity of claim 8 or 9, wherein the positioning entity is the UE.

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