Preventing error propagation for sidelink positioning

Abstract

Systems, methods, and tools are disclosed for preventing error propagation for sidelink positioning. A target wireless transmit / receive unit (WTRU) may select one or more anchor WTRUs from candidate anchor WTRUs based on an uncertainty metric from the selected anchor WTRU being below an error threshold. The target WTRU may determine a target WTRU absolute position and a target WTRU uncertainty metric. The target WTRU may determine an absolute location of the target WTRU using a default location method if the selected anchor WTRU is below a threshold number of anchor WTRUs. The target WTRU may determine the target WTRU uncertainty metric, and the target WTRU uncertainty metric may include an uncertainty of the target WTRU and / or a degree of uncertainty of the target WTRU. The target WTRU may send an indication of the target WTRU absolute location and the target WTRU uncertainty metric to a network node.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 395,966 filed on August 8, 2022, U.S. Provisional Application No. 63 / 445,376 filed on February 14, 2023, and U.S. Provisional Application No. 63 / 465,092 filed on May 9, 2023, the contents of which are incorporated herein by reference. Background Art

[0003] Mobile communications using wireless communications continue to evolve. The fifth generation of mobile communications radio access technology (RAT) may be referred to as 5G New Radio (NR). The previous generation (legacy) mobile communications RAT may be, for example, fourth generation (4G) Long Term Evolution (LTE). Summary of the invention

[0004] Systems, methods, and tools for preventing error propagation for sidelink positioning are disclosed. A target wireless transmit / receive unit (WTRU) may select one or more anchor WTRUs from candidate anchor WTRUs based on an uncertainty metric from a selected anchor WTRU being below an error threshold. The target WTRU may determine a target WTRU absolute position and a target WTRU uncertainty metric. The target WTRU may determine a target WTRU absolute position using a default positioning method if the selected anchor WTRU is below a threshold number of anchor WTRUs. The target WTRU may determine a target WTRU uncertainty metric, and the target WTRU uncertainty metric may include an uncertainty of the target WTRU and / or a degree of uncertainty of the target WTRU. The target WTRU may send an indication of the target WTRU absolute position and the target WTRU uncertainty metric to a network node.

[0005] If the selected anchor WTRU is below a threshold number of anchor WTRUs, the target WTRU uncertainty metric may be associated with the uncertainty of the default positioning method.

[0006] If the selected anchor WTRU is above a threshold number of anchor WTRUs, the target WTRU may use a sidelink positioning method to determine the target WTRU absolute location. If the selected anchor WTRU is above a threshold number of anchor WTRUs, the target WTRU uncertainty metric may be associated with the uncertainty associated with the selected anchor WTRU and the uncertainty associated with the sidelink positioning method.

[0007] If the selected anchor WTRUs are equal to or higher than the threshold number of anchor WTRUs, the target WTRU may use a combination of the sidelink positioning method and the default positioning method to determine the target WTRU absolute location.

[0008] If the sidelink positioning method is used to determine the target WTRU absolute position, the target WTRU may accumulate uncertainty metrics based on the uncertainty metrics associated with each of the selected anchor WTRUs.

[0009] If a default positioning method is used to determine the target WTRU absolute position, the target WTRU may reset the target WTRU uncertainty metric to the uncertainty associated with the default positioning method.

[0010] If the target WTRU enters the network coverage, the target WTRU may send information related to the selected anchor WTRU for positioning to the network node. The information may include an identity of the selected anchor WTRU.

[0011] The target WTRU may receive configuration information indicating a default positioning method, an error threshold, and / or a threshold number of anchor WTRUs.The target WTRU may determine candidate anchor WTRUs and a corresponding uncertainty metric for each of the candidate anchor WTRUs.

[0012] Systems, methods, and tools for preventing error propagation for sidelink positioning are disclosed. A wireless transmit / receive unit (WTRU) may determine an anchor WTRU via a discovery process. The WTRU may select a plurality of anchor WTRUs from the determined anchor WTRUs for positioning, and the number of anchor WTRUs may be determined by sorting the determined anchor WTRUs in descending order based on respective priority levels of the determined anchor WTRUs. The respective priority levels of the determined anchor WTRUs may correspond to respective categories associated with the determined anchor WTRUs. The WTRU may receive respective positioning reference signals from the selected anchor WTRUs. The WTRU may determine respective measurements corresponding to the respective positioning reference signals. The WTRU may report the selected anchor WTRU and the respective measurements to a network.

[0013] The uncertainty metric of the configured positioning method may also be based on the position information uncertainty of the anchor WTRU, assistance data of the anchor WTRU, measurements of the anchor WTRU, the number of anchor WTRUs and / or channel conditions.

[0014] The configured positioning methods may include the following: time difference of arrival (TDOA), round trip time (RTT), angle of arrival (AoA), angle of departure (AoD), global navigation satellite system (GNSS), sensor-based and / or Wi-Fi-based.

[0015] Systems, methods, and tools for preventing error propagation for sidelink positioning are disclosed. A wireless transmit / receive unit (WTRU) may include one or more processors configured to obtain location uncertainty information of an associated anchor WTRU. Whether to select an anchor WTRU may be determined based on the location uncertainty information. In an example, selection of the anchor WTRU may be based on the location uncertainty information being below a preconfigured uncertainty threshold. A cumulative uncertainty associated with the WTRU may be determined. In an example, the cumulative uncertainty may be a corresponding positioning error based on a determination by the WTRU of the location of the WTRU without using the anchor WTRU. In an example, the cumulative uncertainty may be accumulated based on a determination by the WTRU of the location of the WTRU using the anchor WTRU.

[0016] The WTRU may determine an anchor WTRU via a discovery process. The WTRU may select a plurality of anchor WTRUs for positioning from the determined anchor WTRUs. The plurality of anchor WTRUs may be determined by sorting the determined anchor WTRUs in descending order based on a respective priority level of each of the determined anchor WTRUs. The respective priority level of each of the determined anchor WTRUs may correspond to a respective category associated with each of the determined anchor WTRUs. The WTRU may receive a respective positioning reference signal from each of the selected anchor WTRUs. The WTRU may determine a respective measurement corresponding to each respective positioning reference signal. The WTRU may report the selected anchor WTRU and the respective measurement to the network.

[0017] The WTRU may receive or be pre-configured with a list of anchor WTRUs. The list may identify a corresponding category for each anchor WTRU in the list. Each corresponding category may be associated with a corresponding priority.

[0018] The WTRU may receive an indication of a positioning method from the network. The WTRU may use the determination of the anchor WTRU in the received positioning method.

[0019] A wireless transmit / receive unit (WTRU) may determine an anchor WTRU via a discovery process. The WTRU may select a positioning anchor WTRU from the anchor WTRUs for a positioning method. The positioning anchor WTRU may be determined in descending order based on a priority level, and the priority level may correspond to a category associated with the positioning anchor WTRU. The WTRU may receive a positioning reference signal from the positioning anchor WTRU. The WTRU may determine measurements corresponding to the positioning reference signal. The WTRU may report the measurements and the positioning anchor WTRU to a network.

[0020] The WTRU may be pre-configured with a plurality of categories for positioning anchor WTRUs, and each of the plurality of categories may be associated with a priority level.The WTRU may receive a positioning method from the network.

[0021] Downlink, uplink, and downlink and uplink positioning methods may be used for positioning. Such methods may use signals (e.g., positioning reference signals, sounding reference signals, and sounding reference signals for positioning purposes). The environment may play an important role (e.g., a critical role) in measuring the signals, thereby affecting the positioning accuracy. In sidelink (SL) positioning, the positioning of the WTRU may be determined (e.g., by the target WTRU) based on measurements of a SL positioning reference signal (SL PRS) sent by an anchor WTRU. The positioning of the target WTRU may be determined (e.g., by the target WTRU) based on the absolute positioning of the target WTRU and the relative positioning of the target WTRU with respect to the positioning of the anchor WTRU (e.g., the position of the anchor WTRU).

[0022] The absolute positioning of the target WTRU (e.g., the WTRU to be positioned) may be determined using the absolute positioning of the anchor WTRU (e.g., the first anchor WTRU). Such determination may include avoiding Uu positioning and such associated overhead or GNSS / GPS (e.g., GNSS / GPS may consume power and time to perform accurate positioning).

[0023] The absolute position of the first anchor WTRU may be derived based on the absolute position of the second anchor WTRU.Errors associated with the absolute position of the first anchor WTRU and the absolute position of the second anchor WTRU may be propagated to the absolute position of the target WTRU.

[0024] An anchor WTRU may be selected (e.g., by a target WTRU) based on a position uncertainty estimated at a target WTRU (e.g., where the target WTRU may determine an estimated position error based on a position error uncertainty measured by the anchor WTRU (e.g., using reference signal received power (RSRP) and reference signal time difference (RSTD)).

[0025] The location uncertainty information may include an uncertainty metric and / or a location uncertainty at the target WTRU. The location uncertainty information may be compared to a value such as a threshold. In an example, the location uncertainty information may be above a pre-configured threshold. If the uncertainty is above a pre-configured threshold, a determination may be made (e.g., by the target WTRU) to use a default positioning method. The default positioning method may rely on GNSS / GPS and / or Uu positioning. The default positioning method may set the uncertainty (e.g., location uncertainty) to the uncertainty of the GNSS / GPS positioning (e.g., the degree of uncertainty may be set to zero (0)).

[0026] A first set of anchor WTRUs may be determined (e.g., by a target WTRU) based on a first metric (e.g., a degree of uncertainty). Within the first set of WTRUs (e.g., anchor WTRUs), the target WTRUs may determine a second set of anchor WTRUs based on a second metric (e.g., an uncertainty associated with absolute positioning). BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1A is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented.

[0028] Figure 1B is an example of a method that can be used according to an embodiment of the present invention. Figure 1A A system diagram of an example wireless transmit / receive unit (WTRU) for use within an illustrated communication system.

[0029] Figure 1C is an example of a method that can be used according to an embodiment of the present invention. Figure 1A System diagram of an example Radio Access Network (RAN) and an example Core Network (CN) for use within the illustrated communication system.

[0030] Figure 1D is an example of a method that can be used according to an embodiment of the present invention. Figure 1A System diagram of another example RAN and another example CN for use within the illustrated communication system.

[0031] Figure 2 An example of error propagation is illustrated.

[0032] Figure 3 Examples of positioning determination of a WTRU with different degrees of uncertainty are illustrated.

[0033] Figure 4 An example of selecting an anchor WTRU based on the degree of uncertainty is illustrated.

[0034] Figure 5 An example signal flow diagram for determining an anchor WTRU is illustrated.

[0035] Figure 6 An example of selecting an anchor WTRU for out of coverage is illustrated. DETAILED DESCRIPTION

[0036] Systems, methods, and tools related to preventing error propagation for sidelink positioning are described herein.

[0037] Figure 1A1 is a diagram illustrating an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc. to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content through sharing of system resources (including wireless bandwidth). In an example, the communication system 100 may employ one or more channel access methods such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), zero tail unique word DFT spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, and filter bank multi-carrier (FBMC), etc.

[0038] like Figure 1A As shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RAN 104 / 113, CN 106 / 115, public switched telephone network (PSTN) 108, Internet 110 and other networks 112, but it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the UE 102a, 102b, 102c, 102d (any of which may be referred to as a “station” and / or “STA”) may be configured to send and / or receive wireless signals and may include a user equipment (WTRU), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smart phone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated process chain environment), a consumer electronic device, a device operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0039] The communication system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device that is configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106 / 115, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node B, an eNode B, a Home Node B, a Home eNode B, a gNB, an NR Node B, a site controller, an access point (AP), a wireless router, and the like. Although the base stations 114a, 114b are each depicted as a single element, it should be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0040] Base station 114a may be part of RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as base station controllers (BSC), radio network controllers (RNC), relay nodes, etc. Base station 114a and / or base station 114b may be configured to send and / or receive wireless signals on one or more carrier frequencies (which may be referred to as cells (not shown)). These frequencies may be in a licensed spectrum, an unlicensed spectrum, or a combination of a licensed spectrum and an unlicensed spectrum. A cell may provide coverage of wireless services to a specific geographic area, which may be relatively fixed or may change over time. The cell may be further divided into cell sectors. In an example, the cell associated with base station 114a may be divided into three sectors. Therefore, in one embodiment, base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In an embodiment, base station 114a may employ multiple-input multiple-output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. In an example, beamforming may be used to send and / or receive signals in a desired spatial direction.

[0041] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0042] More specifically, as noted above, the communication system 100 may be a multiple access system and may employ one or more channel access schemes such as CDMA, TDMA, FDMA, OFDMA, and SC-FDMA. In an example, the base station 114a in the RAN 104 / 113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may use Wideband CDMA (WCDMA) to establish the air interface 115 / 116 / 117. WCDMA may include communication protocols such as High Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High Speed ​​UL Packet Access (HSUPA).

[0043] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA) that may establish the air interface 116 using Long Term Evolution (LTE) and / or Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-A Pro).

[0044] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR radio access, which may establish the air interface 116 using New Radio (NR).

[0045] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. In an example, the base station 114a and the WTRUs 102a, 102b, 102c may together implement LTE radio access and NR radio access, for example using dual connectivity (DC) principles. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions transmitted to / from multiple types of base stations (e.g., eNBs and gNBs).

[0046] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), and GSM EDGE (GERAN).

[0047] Figure 1A The base station 114b in may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in local areas such as commercial venues, homes, vehicles, campuses, industrial facilities, sky corridors (e.g., for use by drones), and roads. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology (such as IEEE 802.11) to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology (such as IEEE 802.15) to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a picocell or a femtocell. As Figure 1A As shown, base station 114b may have a direct connection to Internet 110. Therefore, base station 114b may not need to access Internet 110 via CN 106 / 115.

[0048] The RAN 104 / 113 may be in communication with the CN 106 / 115, which may be any type of network configured to provide voice, data, applications and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not described in detail in the text and video, the CN 106 / 115 may be configured to provide voice, data, applications and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Figure 1AAlthough not shown in the figure, it will be appreciated that the RAN 104 / 113 and / or the CN 106 / 115 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 / 113 or a different RAT. In the example, in addition to being connected to the RAN 104 / 113, which may utilize NR radio technology, the CN 106 / 115 may also be in communication with another RAN (not shown) that employs GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0049] The CN 106 / 115 may also act as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and / or the Internet Protocol (IP) in the TCP / IP Internet protocol suite. The networks 112 may include wired communication networks and / or wireless communication networks owned and / or operated by other service providers. In an example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 / 113 or a different RAT.

[0050] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks via different wireless links). Figure 1A The illustrated WTRU 102c may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0051] Figure 1B is a system diagram illustrating an example WTRU 102. Figure 1B As shown, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0052] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC) and state machine, etc. The processor 118 may perform signal decoding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. Although Figure 1B The processor 118 and the transceiver 120 are depicted as separate components, but it is understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0053] The send / receive element 122 may be configured to send a signal to a base station (e.g., base station 114a) or receive a signal from a base station via an air interface 116. In an example, in one embodiment, the send / receive element 122 may be an antenna configured to send and / or receive an RF signal. In an embodiment, the send / receive element 122 may be a transmitter / detector configured to send and / or receive, for example, an IR, UV, or visible light signal. In another embodiment, the send / receive element 122 may be configured to send and / or receive both an RF signal and an optical signal. It should be understood that the send / receive element 122 may be configured to send and / or receive any combination of wireless signals.

[0054] Although the transmit / receive element 122 Figure 1B Although depicted as a single element in the figure, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0055] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and to demodulate signals received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. For example, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0056] The processor 118 of the WTRU 102 may be coupled to and may receive user input data from a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from and store data in any type of suitable memory, such as a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, and a secure digital (SD) memory card, among others. In other embodiments, the processor 118 may access information from and store data in a memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0057] The processor 118 may receive power from the power source 134 and may be configured to distribute and / or control power to other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. In an example, the power source 134 may include one or more dry cell batteries (e.g., nickel cadmium (NiCd), nickel zinc (NiZn), nickel metal hydride (NiMH), lithium ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0058] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or in lieu of the information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by any suitable location-determination method while remaining consistent with an embodiment.

[0059] The processor 118 may also be coupled to other peripherals 138, which may include one or more software modules and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. In an example, the peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, module, FM radio unit, digital music player, media player, video game player module, Internet browser, virtual reality and / or augmented reality (VR / AR) device and activity tracker, etc. Peripheral device 138 may include one or more sensors, which may be one or more of the following: gyroscope, accelerometer, Hall effect sensor, magnetometer, orientation sensor, proximity sensor, temperature sensor, time sensor; geolocation sensor; altimeter, light sensor, touch sensor, magnetometer, barometer, gesture sensor, biometric sensor and / or humidity sensor.

[0060] The WTRU 102 may include a full-duplex radio for which transmission and reception of some or all signals (e.g., associated with specific subframes for both UL (e.g., for transmission) and downlink (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit for reducing and / or substantially eliminating self-interference via hardware (e.g., a choke) or via signal processing performed by a processor (e.g., a separate processor (not shown) or via the processor 118). In one embodiment, the WRTU 102 may include a half-duplex radio for which transmission and reception of some or all signals (e.g., associated with specific subframes for both UL (e.g., for transmission) or downlink (e.g., for reception)) may be concurrent and / or simultaneous.

[0061] Figure 1C 1 is a system diagram illustrating the RAN 104 and the CN 106 in accordance with an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0062] The RAN 104 may include evolved Node-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of evolved Node-Bs while remaining consistent with an embodiment. The evolved Node-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the evolved Node-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the evolved Node-B 160a, for example, may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0063] Each of the evolved Node Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, and scheduling of users in the UL and / or DL, among other things. Figure 1C As shown, the eNode-Bs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0064] Figure 1C The illustrated CN 106 may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements is depicted as being part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0065] The MME 162 may be connected to each of the evolved Node-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. In an example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, and selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, among other things. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0066] The SGW 164 may be connected to each of the evolved Node-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring the user plane during an inter-evolved Node-B handover, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, and managing and storing the context of the WTRUs 102a, 102b, 102c.

[0067] The SGW 164 may be connected to the PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0068] The CN 106 may facilitate communications with other networks. In an example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. In an example, the CN 106 may include or may be in communication with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers.

[0069] Although the WTRU Figures 1A to 1D Although described as wireless terminals, it is contemplated that in certain representative embodiments, such terminals may (eg, temporarily or permanently) use a wired communications interface with a communications network.

[0070] In a representative embodiment, the other network 112 may be a WLAN.

[0071] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for a BSS and one or more stations (STAs) associated with the AP. The AP may have access or an interface to a distribution system (DS) or another type of wired / wireless network that carries services to and / or out of the BSS. Traffic originating from outside the BSS and destined for the STA may be reached by the AP and may be delivered to the STA. Traffic originating from the STA and destined for a target outside the BSS may be transmitted to the AP to be delivered to the corresponding target. Traffic between STAs within the BSS may be transmitted by the AP, for example, wherein the source STA may transmit traffic to the AP, and the AP may deliver traffic to the target STA. Traffic between STAs within the BSS may be considered and / or referred to as point-to-point traffic. Point-to-point traffic may be transmitted between the source STA and the target STA (e.g., directly between them) using a direct link setup (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunnel DLS (TDLS). A WLAN using an independent BSS (IBSS) mode may not have an AP, and STAs within or using the IBSS (eg, all STAs in the STA) may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad hoc" communication mode.

[0072] When using the 802.11ac infrastructure operation mode or a similar operation mode, the AP may send beacons on a fixed channel (such as a primary channel). The primary channel may be a fixed width (e.g., a 20 MHz wide bandwidth) or a width dynamically set via signaling. The primary channel may be an operating channel of the BSS and may be used by the STA to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access / collision avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. For CSMA / CA, a STA (e.g., each STA) (including the AP) may listen to the primary channel. If the primary channel is listened / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0073] High throughput (HT) STAs may communicate using a 40 MHz wide channel (eg, via a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels) to form a 40 MHz wide channel.

[0074] Very high throughput (VHT) STA can support 20MHz, 40MHz, 80MHz and / or 160MHz wide channels. 40MHz channels and / or 80MHz channels can be formed by combining continuous 20MHz channels. 160MHz channels can be formed by combining 8 continuous 20MHz channels, or by combining two non-continuous 80MHz channels (this can be called 80+80 configuration). For 80+80 configuration, after channel coding, the data can pass through a segment parser that can divide the data into two streams. Each stream can be processed by inverse fast Fourier transform (IFFT) and time domain processing separately. These streams can be mapped to two 80MHz channels, and the data can be sent by the transmitting STA. At the receiver of the receiving STA, the above-mentioned operation for the 80+80 configuration can be reversed, and the combined data can be transmitted to the medium access control (MAC).

[0075] 802.11af and 802.11ah support operating modes below 1GHz. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah relative to those used in 802.11n and 802.11ac. 802.11af supports 5MHz, 10MHz, and 20MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support instrument type control / machine type communications, such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support for (e.g., only support for) certain bandwidths and / or limited bandwidths. MTC devices may include batteries with battery life above a threshold (e.g., to maintain very long battery life).

[0076] WLAN systems that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) include channels that can be designated as primary channels. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA (which supports the minimum bandwidth operating mode) from all STAs operating in the BSS. In the example of 802.11ah, for STAs (e.g., MTC-type devices) that support (e.g., only support) a 1MHz mode, the primary channel may be 1MHz wide, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) settings may depend on the state of the primary channel. If the primary channel is busy, for example, because a STA (supporting only a 1MHz operating mode) is sending to the AP, the entire available band may be considered busy even if most of the band remains idle and may be available.

[0077] In the United States, the available frequency band for 802.11ah is 902MHz to 928MHz. In South Korea, the available frequency band is 917.5MHz to 923.5MHz. In Japan, the available frequency band is 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz, depending on the country code.

[0078] Figure 1D 1 is a system diagram illustrating the RAN 113 and the CN 115 in accordance with an embodiment. As noted above, the RAN 113 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0079] The RAN 113 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. In an example, the gNBs 180a, 180b may utilize beamforming to send signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a may, for example, use multiple antennas to send wireless signals to and / or receive wireless signals from the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. In an example, gNB 180a may transmit multiple component carriers to WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum, while the remaining component carriers may be on licensed spectrum. In an embodiment, gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) technology. In an example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0080] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with scalable parameter sets. In examples, OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or transmit time intervals (TTIs) of varying or scalable lengths (e.g., containing different numbers of OFDM symbols and / or varying absolute time lengths).

[0081] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c while not accessing other RANs (e.g., such as the eNodeBs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may use one or more of the gNBs 180a, 180b, 180c as mobility anchor points. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect with the gNB 180a, 180b, 180c while also communicating / connecting with another RAN, such as the eNodeB 160a, 160b, 160c. In an example, the WTRUs 102a, 102b, 102c may implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNodeBs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNodeB 160a, 160b, 160c may act as a mobility anchor for the WTRUs 102a, 102b, 102c, and the gNB 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0082] Each of the gNBs 180a, 180b, 180c may be associated with a specific cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and / or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards a user plane function (UPF) 184a, 184b and routing of control plane information towards an access and mobility management function (AMF) 182a, 182b, etc. Figure 1D As shown, gNBs 180a, 180b, and 180c may communicate with each other via an Xn interface.

[0083] Figure 1DThe illustrated CN 115 may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and possible data networks (DNs) 185a, 185b. Although each of the foregoing elements is depicted as part of the CN 115, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0084] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N2 interface and may act as a control node. In an example, the AMF 182a, 182b may be responsible for authenticating users of the WTRU 102a, 102b, 102c, support of network slicing (e.g., handling of different PDU sessions with different requirements), selecting a specific SMF 183a, 183b, management of registration areas, termination of NAS signaling, mobility management, etc. The AMF 182a, 182b may use network slicing to customize CN support for the WTRU 102a, 102b, 102c based on the type of services utilized by the WTRU 102a, 102b, 102c. In an example, different network slices may be established for different use cases, such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced mobile broadband (eMBB) access, and / or services for machine type communication (MTC) access, etc. The AMF 162 may provide a control plane function for switching between the RAN 113 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies, such as WiFi.

[0085] The SMF 183a, 183b may be connected to the AMF 182a, 182b in the CN 115 via the N11 interface. The SMF 183a, 183b may also be connected to the UPF 184a, 184b in the CN 115 via the N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b, and configure traffic routing through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions such as managing and allocating WTRU IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0086] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, and providing mobility anchoring, etc.

[0087] The CN 115 may facilitate communications with other networks. In an example, the CN 115 may include or may communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to the local data network (DN) 185a, 185b via the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and the N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0088] Given that Figures 1A to 1D as well as Figures 1A to 1D Corresponding to the description of the present invention, one or more or all of the functions described herein with reference to one or more of the following may be performed by one or more simulation devices (not shown): WTRU102a-d, base station 114a-b, evolved Node B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF182a-b, UPF 184a-b, SMF 183a-b, DN 185a-b and / or any other device described herein. The simulation device may be one or more devices configured to mimic one or more or all of the functions described herein. In an example, the simulation device may be used to test other devices and / or simulate network and / or WTRU functions.

[0089] The simulation device may be designed to implement one or more tests of other devices in a laboratory environment and / or in an operator network environment. In an example, one or more simulation devices may perform one or more functions or all functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. One or more simulation devices may perform one or more functions or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The simulation device may be directly coupled to another device for testing purposes and / or may use over-the-air wireless communications to perform testing.

[0090] One or more simulation devices can perform one or more (including all) functions without being implemented / deployed as a part of a wired and / or wireless communication network. In an example, the simulation device can be used in a test scenario in a test laboratory and / or a non-deployed (e.g., testing) wired and / or wireless communication network to implement the test of one or more components. One or more simulation devices can be test equipment. Direct RF coupling and / or wireless communication performed via RF circuits (e.g., which can include one or more antennas) can be used by the simulation device to send and / or receive data.

[0091] The configuration referred to herein (eg, a configuration received at a WTRU) may refer to configuration information.

[0092] This description is provided for exemplary purposes and does not in any way limit the applicability of the methods described herein to other wireless technologies. The term network may refer to one or more gNBs associated with one or more transmit / receive points (TRPs), or may refer to any other node in a radio access network (RAN).

[0093] The timing / angle positioning method may include a positioning method using a reference signal (e.g., SL-PRS). The reference signal may be received (e.g., by the WTRU). RSTD, RSRP, and / or AoA may be measured (e.g., by the WTRU). In an example, the angle / timing positioning method may include SL-AoD or SL-TDOA positioning. The SL-PRS may be sent (e.g., by the WTRU and between WTRUs). The receiver may perform measurements (e.g., RSTD, AoA, RSRP) to determine the location of the WTRU (e.g., the WTRU sending the SL-PRS).

[0094] The RTT positioning method may include a positioning method that may include two (2) WTRUs to send SL-PRS between each other. In an example, the anchor WTRU may send the SL-PRS to the target WTRU. The target WTRU may receive the SL-PRS from the anchor WTRU. The target WTRU may send the SL-PRS to the anchor WTRU. The target WTRU may measure the WTRU Tx-Rx time delta (e.g., the difference between the transmission time of the SL-PRS from the target WTRU and the reception time of the SL-PRS sent from the anchor WTRU). The target WTRU may report the WTRU Tx-Rx time difference to the anchor WTRU.

[0095] The positioning methods described herein may be used to determine a relative position and / or an absolute position (eg, an absolute position according to a geographic coordinate system or a local coordinate system) of a target WTRU with respect to an anchor WTRU.

[0096] Positioning may be provided. In an example, the absolute positioning of the WTRU may be expressed in terms of a geographic coordinate system (GCS) or a local coordinate system (LCS). In an example, the relative positioning of the target WTRU may be expressed in terms of a distance from a second WTRU (e.g., an anchor WTRU), an angle from a second WTRU (e.g., an anchor WTRU), or one or more of a reference point with a known location.

[0097] The SL-PRS configuration may include at least one or more of the following: SL-PRS resource ID, SL-PRS sequence ID (or other ID used to generate SL-PRS sequence), SL-PRS resource element offset, SL-PRS resource slot offset, SL-PRS symbol offset, SL-PRS QCL information, SL-PRS resource set ID, SL-PRS resource list in the resource set, the number of SL-PRS symbols, a muting mode for SL-PRS, muting parameters (such as repetition factor, muting option), SL-PRS resource power, periodicity of SL-PRS transmission, spatial direction information of SL-PRS transmission (e.g., beam information and / or transmission angle), spatial direction information of SL-RS reception (e.g., beam ID and / or arrival angle for receiving SL-RS), frequency layer ID, WTRU ID or SL-PRS ID.

[0098] The network may include one or more of an AMF, a gNB, or a NG-RAN. "Pre-configuration" and "configuration" may be used interchangeably herein. "Non-serving gNB" and "neighboring gNB" may be used interchangeably herein. "gNB" and "TRP" may be used interchangeably herein. "PRS" or "PRS resource" may be used interchangeably herein. "PRS" or "PRS resource" may be used interchangeably herein. The aforementioned terms "PRS" or "PRS resource" may belong to different PRS resource sets. "PRS" or "DL-PRS" or "DL PRS" may be used interchangeably herein. "Measurement gap" and "measurement gap pattern" may be used interchangeably herein. "Measurement gap pattern" may include parameters (e.g., including measurement gap duration, measurement gap repetition period, and measurement gap periodicity).

[0099] A PRU may include a WTRU or a TRP. A WTRU or a TRP may include a location (e.g., altitude, latitude, longitude, geographic coordinates, or local coordinates) known to the network (e.g., a gNB or LMF). A PRU may be the same as (e.g., have the same capabilities) as a WTRU or a TRP (e.g., be able to receive a PRS or send an SRS or an SRS for positioning, return measurements, or send a PRS). A WTRU acting as a PRU may be used (e.g., by the network) for calibration purposes (e.g., correcting an unknown timing offset, correcting an unknown angle offset).

[0100] The LMF may be a node or entity (eg, a network node of an entity) that may support positioning (eg, may be used for or support positioning). The node or entity may replace the LMF.

[0101] Measurements may be obtained. These measurements may be associated with the positioning of the WTRU. In an example, the absolute positioning of a target WTRU (e.g., a WTRU to be positioned) may be determined using the absolute positioning of a second WTRU (e.g., a first anchor WTRU). Using the absolute positioning of the second WTRU may avoid Uu positioning and the associated overhead or GNSS / GPS (e.g., for precise positioning) that may consume power and time.

[0102] In an example, when deriving the absolute location of the second WTRU based on the absolute location of the second anchor WTRU, errors associated with the absolute locations of the first anchor WTRU absolute location and the second anchor WTRU absolute location may be propagated to the absolute location of the target WTRU.

[0103] Figure 2An example of error propagation is illustrated. In this example, the absolute position of WTRU_B 202 may be determined (e.g., by WTRU_B 202) based on the position information of WTRU_A 204 and the relative position of WTRU_B 202 with respect to WTRU_A 204. If the position information of WTRU_A 204 contains an error, as indicated by "err1" in the figure, the resulting cumulative uncertainty in the position of WTRU_B 202 may become err1+err2, where err2 is the uncertainty associated with the relative position between WTRU_B 202 and WTRU_A 204. The absolute position of WTRU_C 206 may be determined (e.g., by WTRU_C 206) based on the absolute position of WTRU_B 202. The accumulated uncertainty of the position of WTRU_C 206 becomes err1+err2+err3, where err2 is the uncertainty associated with the relative positioning between WTRU_C 206 and WTRU_B 202 (eg, if the absolute positioning of WTRU_C 206 is determined by WTRU_C 206 based on the absolute positioning of WTRU_B 202).

[0104] Figure 3 An example of error propagation is illustrated. With respect to error propagation, Anchor_A 302, Anchor_B 304, and Anchor_C 306 may be used (e.g., by a target WTRU for SL TDOA positioning 308). GNSS / GPS 309 may be used (e.g., by Anchor_A 302) to determine an absolute position of Anchor_A 302. SL positioning may be used (e.g., by Anchor_B 304 together with WTRU_D 310) to determine an absolute position of Anchor_B. GNSS / GPS may be used (e.g., by WTRU_E 312) to determine the position of WTRU_E 312. Errors associated with an absolute position (e.g., the absolute position of WTRU_F 314) may be propagated to the absolute position of Anchor_B 304. The absolute position of Anchor_C 306 may be determined (e.g., by Anchor_C 306) based on the SL positioning (e.g., using the SL positioning of WTRU_F 314). The absolute positioning of WTRU_F 314 may be determined (e.g., by WTRU_F 314) based on Uu positioning. Errors associated with WTRU_F 314 may propagate to the absolute positioning (e.g., of Anchor_C 306). Different degrees of error may affect the anchor WTRU (e.g., WTRU). The accumulated error at the anchor WTRU may affect the accuracy of the absolute positioning of the target WTRU.

[0105] Position uncertainty information may be determined based on or may include one or more types of errors. Position uncertainty, position uncertainty information, uncertainty metrics, and uncertainty are used interchangeably herein. In an example, at least one of the following uncertainty metrics may be used (e.g., by a WTRU) to determine whether an anchor WTRU may use SL positioning. In an example, the metric may include uncertainty regarding the absolute positioning of the anchor WTRU. In an example, the metric may include an uncertainty level associated with the absolute positioning of the anchor WTRU. The uncertainty level (e.g., a level associated with an absolute uncertainty associated with the absolute positioning of the anchor WTRU) may be a quantified uncertainty regarding the absolute positioning of the anchor WTRU. The uncertainty metric may include a degree of uncertainty associated with the absolute positioning of the anchor WTRU, wherein the degree indicates how many times the original actual positioning has been referenced (e.g., to determine the current absolute positioning). The uncertainty metric may include an estimated uncertainty in the absolute positioning of the target WTRU.

[0106] For certain types of errors, the target WTRU may be configured with error criteria (e.g., the degree of uncertainty may be less than a preconfigured threshold, the uncertainty about the absolute positioning of the anchor WTRU may be less than a preconfigured threshold) to determine whether the WTRU can be used for SL positioning.

[0107] Absolute positioning and relative positioning may be used interchangeably herein. In an example, relative positioning may be defined as positioning relative to a reference node (eg, distance and angle relative to a reference node).

[0108] In an example, if the target WTRU is within coverage of the network, a set of anchor WTRUs may be received (e.g., the target WTRU may receive a set of anchor WTRUs from the network). Assistance information may be received (e.g., the target WTRU may receive assistance information about absolute positioning and uncertainty metrics from the network associated with the anchor WTRU from the network). If the target WTRU is out of coverage of the network, a positioning request may be transmitted (e.g., the target WTRU may transmit or broadcast a positioning request to nearby WTRUs). The target WTRU may wait for a response from the anchor WTRU and may determine (e.g., by the target WTRU) that there are nearby anchor WTRUs (e.g., an anchor WTRU with which the target WTRU performs SL positioning). Assistance information associated with the anchor WTRU may be received (e.g., by the target WTRU) from the anchor WTRU (e.g., the assistance information may include absolute positioning and uncertainty metrics).

[0109] The WTRU may determine uncertainty information related to the location of the WTRU. The uncertainty related to the absolute positioning (e.g., of the target WTRU) may be defined as follows. The uncertainty related to the absolute positioning (e.g., of the target WTRU) may be expressed (e.g., as a range) with respect to the absolute positioning. In an example, if the uncertainty of the horizontal positioning is ±2m, and the estimated position on the horizontal axis is at 1.5m from the origin, then the possible position (e.g., of the target WTRU) may be between -0.5m and 3.5m.

[0110] A list of anchor WTRUs may be received (e.g., by the WTRU from a network). Information related to the anchor WTRUs, such as an absolute position and its associated uncertainty, may be received (e.g., by the target WTRU). If the uncertainty regarding the absolute position (e.g., of the anchor WTRU) is less than or equal to a preconfigured threshold, a determination may be made (e.g., by the target WTRU) to use the anchor WTRU.

[0111] An indication may be received (e.g., received by the target WTRU from the network) to find at least N anchor WTRUs to perform a positioning method (e.g., SL-TDOA). If the target WTRU cannot find N anchor WTRUs, a determination may be made (e.g., by the target WTRU) to perform a default positioning method that does not rely on an anchor WTRU (e.g., positioning based on DL-TDOA or GNSS / GPS). If no default positioning method is configured, a determination may be made (e.g., by the WTRU) to transmit a request for a positioning method to the anchor WTRU and / or the network (e.g., LMF, gNB).

[0112] If N anchor WTRUs are found (eg, by a target WTRU) whose position uncertainties are below a threshold, then it may be determined (eg, by a target WTRU) using the following example.

[0113] In an example, the uncertainty of the positioning of the target WTRU may be determined (e.g., determined by the target WTRU) based on the uncertainty (e.g., the uncertainty of the position of the anchor WTRU). If more than one anchor WTRU is used for positioning, the uncertainty associated with the position of the target WTRU may be determined (e.g., determined by the target WTRU) to derive an overall uncertainty based on the uncertainty (e.g., the uncertainty of the absolute position of the anchor WTRU) using a function. These examples are described herein.

[0114] In an example, the accumulated uncertainty associated with the position of the anchor WTRU may be determined (e.g., by the target WTRU). If the position of the target WTRU is determined (e.g., by the target WTRU) based on PRS transmitted from at least 3 anchor WTRUs, and the uncertainty ranges of the positions of the at least 3 anchor WTRUs are based on ±3m, ±2m, ±5m, respectively, it may be determined (e.g., by the WTRU) that the uncertainty associated with the position is 3+2+5=10 meters. The uncertainty based on the measurement error and the uncertainty associated with the time of arrival of the SL-PRS, RSTD, AoA, and / or AoD may be determined (e.g., by the WTRU).

[0115] In an example, an indication may be received (e.g., received by a target WTRU) to calculate the uncertainty based on a weight. In an example, the weight may be determined (e.g., determined by the target WTRU) based on the RSRP of the SL-PRS received from the anchor WTRU. It may be determined (e.g., by the WTRU) to calculate a sum of RSRP and divide the RSRP by the sum (e.g., to obtain the weight). Based on the weight, the WTRU may determine the uncertainty by applying the weight to the uncertainty.

[0116] In an example, the target WTRU may indicate which error sources contribute to the uncertainty (e.g., of the absolute positioning of the WTRU). If the target WTRU becomes the anchor WTRU, the association between the error sources and the absolute positioning of the target WTRU may be included in the assistance information provided to another target WTRU. The error sources may include at least one or more of the following: errors associated with the absolute positioning of the anchor WTRU; measurement errors (e.g., ToA, RSTD, RSRP, WTRU Tx-Rx time); LOS / NLOS indicators associated with the measurements; transmit or receive timing errors (e.g., at the anchor WTRU or the target WTRU); synchronization errors (e.g., between anchor WTRUs, clock synchronization errors).

[0117] Features described herein may include WTRU behavior (eg, correlated WTRU behavior) for determining uncertainty in a WTRU location based on a degree of uncertainty.

[0118] The degree of uncertainty may include the following. In an example, the degree of uncertainty may indicate the number of times the absolute position of the anchor WTRU is inherited. The degree of uncertainty may indicate how often (e.g., the number of times) uncertainty has been associated with an absolute position that has been determined in the past. In an example, the degree of uncertainty may indicate how often (e.g., the number of times) uncertainty has been added to an absolute position that has been determined (e.g., determined in the past).

[0119] Examples of determining the degree of uncertainty may include the following. When an absolute positioning using a first anchor WTRU is determined (e.g., determined by a first target WTRU), the degree of uncertainty may be (e.g., inherited by the first target WTRU from the first anchor WTRU) and the degree of uncertainty may be incremented by a one (1) count (e.g., the degree of uncertainty associated with the first target WTRU). When the first target WTRU becomes a second anchor WTRU and the second target WTRU determines an absolute positioning using the second anchor WTRU, the second target WTRU may inherit the degree of uncertainty of the second anchor WTRU and increment the degree by a one (1) count. If the first anchor WTRU determines its position using a positioning method that does not require an anchor WTRU, the first anchor may reset the degree of uncertainty to zero.

[0120] A WTRU with zero uncertainty level may include a WTRU that determines the absolute positioning of the WTRU based on a method that does not rely on an anchor WTRU's absolute positioning (e.g., Uu positioning, sensor-based positioning, WiFi-based positioning, and / or GNSS / GPS positioning). Such a WTRU may be a roadside unit (RSU) and / or a positioning reference unit (PRU).

[0121] exist Figure 2 In the example shown, the degree of uncertainty at WTRU_C 206 is two (2) because the absolute position of WTRU_A 204 is inherited twice (eg, once to WTRU_B 202 and the absolute position of WTRU_B 202 is inherited to WTRU_C 206).

[0122] If the absolute positioning (e.g., the absolute positioning of the target WTRU) is determined (e.g., by the target WTRU) as being based on more than one anchor WTRU and the anchor WTRUs have different degrees of uncertainty, it may be determined (e.g., by the target WTRU) to perform at least one of the following for inheritance.

[0123] In the example (for example, Figure 3 ), it may be determined to inherit the highest uncertainty level (e.g., the highest uncertainty level among the anchor WTRUs) and increment that level by 1. In the example, if the uncertainty levels of anchor_A 302, anchor_B 304, and anchor_C 306 are 3, 5, and 3, respectively, the target WTRU 308 may determine to set its uncertainty level to six (6).

[0124] In an example, an average of the uncertainty levels between the anchor WTRUs may be determined and incremented by 1. In an example, if the uncertainty levels of anchor_A, anchor_B, and anchor_C are 3, 5, and 3, respectively, the target WTRU may determine the average as ceil((3+5+3) / 3)+1=5, where ceil(x) is a ceiling function that rounds x up to the nearest integer.

[0125] In an example, a determination may be made, for example, by (a target WTRU), to use an anchor WTRU for positioning based on an associated degree of uncertainty (e.g., a degree of uncertainty associated with the anchor WTRU). In an example, a determination may be made (e.g., by the target WTRU) to use an anchor WTRU having a degree of uncertainty below a preconfigured threshold. In an example, an indication / configuration may be received (e.g., by the target WTRU) from a network or anchor WTRU having a threshold of 1. Thus, a determination may be made (e.g., by the target WTRU) to use an anchor WTRU having a degree of uncertainty equal to 0, which may be an RSU, PRU, gNB and / or TRP. Alternatively, the WTRU may be configured to select only RSUs, PRUs, gNBs and / or TRPs as anchor WTRUs for determining the absolute positioning of the WTRU via SL positioning and / or Uu positioning.

[0126] In an example, more than one uncertainty metric (e.g., degree of uncertainty, uncertainty associated with absolute positioning) may be used (e.g., by a target WTRU). In an example, it may be determined (e.g., by a target WTRU) whether to use an anchor WTRU (e.g., for positioning) using both the degree of uncertainty and the uncertainty of absolute positioning (e.g., of an anchor WTRU). In an example, it may be determined (e.g., by a target WTRU) to use an anchor WTRU for positioning if one or more of the following is satisfied: the degree of uncertainty associated with the anchor WTRU is below a first threshold; and / or the uncertainty associated with the absolute positioning of the anchor WTRU is below a second threshold.

[0127] An anchor WTRU may be selected (e.g., by a target WTRU) for SL positioning based on an uncertainty grade or level associated with the error associated with the absolute uncertainty of the anchor WTRU. The error grade may present the level of error, indicating how large the error is, and may also be a quantified uncertainty of the absolute positioning.

[0128] In an example, an error level of -1 may indicate that the error is low, while an error level of 3 may indicate that a larger error may exist. The level may include an error range. In an example, an error level of 1 may include an error less than one (1) meter. For example, a level 2 may include an error greater than or equal to one (1) meter and less than three (3) meters. The absolute positioning (e.g., of an anchor WTRU) may be associated with an error level. A determination may be made (e.g., by a target WTRU) to select an anchor WTRU having an error level below a preconfigured threshold.

[0129] When an absolute positioning is determined (e.g., determined by a target WTRU), an error associated with the positioning may be determined (e.g., determined by the target WTRU) based on the associated uncertainty. The error level may be determined (e.g., determined by the target WTRU) based on at least one or more of the following. The uncertainty associated with the absolute positioning of the target WTRU may be used to determine the error level. In an example, a mapping table may be received (e.g., received by the WTRU from a network and / or an anchor WTRU) with rows having uncertainty ranges for absolute positioning. The error level may be determined using a positioning method. In an example, it may be determined (e.g., determined by the WTRU) that the error level is increased by a certain amount (e.g., for a certain positioning method). In an example, if a TDOA positioning method is used, the level of the level may be incremented by one. Uncertainties in measurements may be used to determine the error level (e.g., time of arrival, RSRP, multipath measurements). The error level may be determined using the number of anchor WTRUs. In an example, if the number of anchor WTRUs used for positioning is greater than a preconfigured threshold, it may be determined (e.g., determined by the WTRU) to increase the level of the level by one (1).

[0130] In an example, if more than one anchor WTRU is used for positioning, the WTRU determines its own rank level as follows. Using the uncertainty associated with the absolute positioning of the anchor WTRU, the target WTRU first determines the uncertainty associated with the absolute positioning of the target WTRU. Using a mapping table, the target WTRU determines its rank, where the mapping table indicates the range of uncertainties and the corresponding error ranks. In an example, error rank one is defined as uncertainty less than 1 meter. For example, rank 2 is defined as uncertainty greater than or equal to one (1) meter and less than three (3) meters. Rank 3 is defined as uncertainty greater than three (3) meters but less than or equal to five (5) meters.

[0131] In an example, the selection of a set of anchor WTRUs for SL positioning may be determined (e.g., by the WTRU) based on an estimated error associated with an absolute positioning of the target WTRU. The target WTRU may determine the estimated error based on assistance information that the target WTRU may have received from the anchor WTRU and / or the network (e.g., LMF, gNB).

[0132] A set of anchor WTRUs may be selected (e.g., by a target WTRU) based on one or more of the following conditions: a preconfigured list (e.g., provided by the anchor WTRU or the network), channel conditions (e.g., the SSB / SL reference signal RSRP associated with the anchor WTRU is above a preconfigured threshold); or LOS / NLOS conditions (e.g., the LOS indicator between the target WTRU and the anchor WTRU is above a preconfigured threshold).

[0133] The anchor WTRUs may be selected (eg, by a target WTRU) to be up to N WTRUs, where N may be the number of WTRUs required by the configured positioning method.

[0134] Based on the selected anchor WTRU, an estimated error may be determined (e.g., by the target WTRU) based on one or more of the following. The estimated error may be determined based on an uncertainty associated with the absolute positioning (e.g., of the anchor WTRU). In an example, the WTRU may determine the cumulative uncertainty associated with the absolute positioning of the anchor WTRU. The estimated error may be determined based on a measurement range (e.g., range of arrival time, RSTD, RSRP) associated with the anchor WTRU. In an example, if the positioning method uses RSTD, the estimated error may be determined (e.g., by the WTRU) based on a mapping function that may map the range of RSTD to the uncertainty of the absolute positioning of the target WTRU. The estimated error may be determined based on the expected value of the measurement (e.g., expected arrival time, expected RSTD, expected RSRP). The estimated error may be determined based on the positioning method. In an example, the WTRU may be configured with a TDOA-based SL positioning method that utilizes a set of anchor WTRUs. The uncertainty associated with the absolute positioning of the target may be determined (e.g., by the WTRU) based on the results of the positioning method.

[0135] In an example, an indication may be received (e.g., by a target WTRU) (e.g., from a network (e.g., LMF, gNB)) indicating which uncertainties to use to determine an estimated error. In an example, the WTRU may determine the estimated error based on a combination of the above uncertainties. In an example, the WTRU determines the estimated error as the sum of the uncertainty of the absolute position of the target WTRU derived from the positioning method and the uncertainty associated with the absolute position of the anchor WTRU used for the positioning method. The target WTRU may use a configured function. The configured function may include a summation, a multiplication, or a weighted summation.

[0136] In an example, if the estimated error is below a preconfigured threshold, a determination may be made (e.g., by the target WTRU) to use a set of anchor WTRUs associated with the estimated error (e.g., the estimated error for SL positioning). If the estimated error is above or equal to the preconfigured threshold, a determination may be made (e.g., by the target WTRU) to select another set of anchor WTRUs and determine the estimated error. If there are no more anchor WTRUs to select (e.g., selected by the target WTRU), a determination may be made (e.g., by the target WTRU) to implement a default positioning method (e.g., Uu positioning, GNSS / GPS based positioning). If the WTRU is not configured with a default positioning, a request may be transmitted (e.g., by the WTRU) to the anchor WTRU or the network to configure a positioning method.

[0137] In the examples described herein, "estimation uncertainty" may be used interchangeably with "degree of estimation uncertainty" or "level of estimation error."

[0138] A combination of selection criteria may be associated with the selection of a WTRU (eg, an anchor WTRU).

[0139] In an example, a configuration may be received (e.g., by a WTRU) related to a priority level of uncertainty for determining an anchor WTRU for SL positioning. In an example, an indication may be received (e.g., from a network and to a WTRU) to use a higher priority level of uncertainty than the uncertainty associated with the absolute positioning of the anchor WTRU.

[0140] In an example, an order of uncertainties for selecting anchor WTRUs may be received (e.g., by a target WTRU). In an example, a first set of anchor WTRUs may be selected (e.g., by a target WTRU) based on the degree of uncertainty. Based on the determined first set of anchor WTRUs, a second set of anchor WTRUs may be determined (e.g., by a target WTRU) based on uncertainties associated with their absolute positioning.

[0141] In an example, a set of anchor WTRUs can be determined (e.g., by a WTRU) based on criteria of uncertainty and measurement. In an example, a first set of anchor WTRUs and uncertainty information related to their absolute positioning can be received (e.g., by the WTRU from the network). Configuration can be received from the network (e.g., by the WTRU) to determine anchor WTRUs based on a degree of uncertainty. Two thresholds can be received (e.g., by the WTRU), a first threshold for the RSRP of the SL reference signal and a second threshold for the degree of uncertainty. The RSRP of the SL reference signal resources from the anchor WTRUs can be measured (e.g., by the WTRU). If the RSRP of the SL reference signal for at least one resource from an anchor WTRU is higher than the first threshold, then if the degree of uncertainty corresponding to the anchor WTRU is higher than the threshold, the target WTRU can determine (e.g., by the target WTRU) to use the anchor WTRU for SL positioning. If the RSRP is lower than the first threshold, then if the associated degree of uncertainty is lower than the second threshold, the target WTRU can determine (e.g., by the target WTRU) to select the anchor WTRU.

[0142] Up to N anchor WTRUs can be associated with a target WTRU.

[0143] In an example, the target WTRU can be configured with N, i.e., the maximum number of anchor WTRUs selected for SL positioning. M anchor WTRUs can be selected (e.g., by the target WTRU), where the availability of the anchor WTRUs based on M < N can meet the uncertainty criteria. In an example, the target WTRU can determine (e.g., by the target WTRU) to select M anchor WTRUs because the degree of uncertainty associated with their absolute positioning is lower than a preconfigured threshold. Which positioning method to use can be determined (e.g., by the target WTRU) based on the available number of anchor WTRUs. In an example, the target WTRU can be preconfigured with a table associating the number of available anchor WTRUs with positioning methods that the target WTRU can use. In an example, the table can indicate that SL-TDOA can be used by the target WTRU if N anchor WTRUs are available. If there are fewer than N available anchor WTRUs, the table can indicate that the target WTRU can use a positioning method based on RTT.

[0144] Figure 4An example of a flow chart (e.g., of selection of an anchor WTRU by a target WTRU based on a degree of uncertainty) is shown in FIG. 402. In this example, at 402, a list of anchor WTRUs may be received (e.g., by the target WTRU from a network). At 404, a degree of error associated with an absolute position of the anchor WTRU may be obtained (e.g., by the target WTRU). At 406, if the degree of error is less than a threshold, the target WTRU may add the anchor WTRU to the pool at 408. At 410, the next anchor WTRU in the list may be selected (e.g., by the target WTRU). At 412, if the counter for the anchor WTRU is below a limit, the search may continue at 414 (e.g., by the target WTRU).

[0145] The fallback behavior can be associated with using a default standard (eg, standard).

[0146] In an example, a configuration of a fallback uncertainty criterion may be received (e.g., by the WTRU). In an example, if an indication is received (e.g., by the WTRU) from the network to use a degree of uncertainty with a higher priority than the uncertainty associated with the absolute positioning of the anchor WTRU, but the degree of uncertainty associated with the absolute positioning of the anchor WTRU is not available, a determination may be made (e.g., by the WTRU) to use a default criterion (e.g., the uncertainty of the absolute positioning) to determine the anchor WTRU for SL positioning.

[0147] If requested (e.g., by the network), a report (e.g., from the WTRU) may be transmitted (e.g., to the network) comprising one or more of: absolute positioning; uncertainty metrics associated with the absolute positioning (e.g., uncertainty, degree of uncertainty); information related to the anchor WTRU, such as the WTRU ID; and measurements used to determine the absolute positioning (e.g., RSRP, RSTD, ToA), where the measurements may be associated with a PRS resource ID, a PRS resource set ID.

[0148] Features described herein may relate to effectiveness with respect to uncertainty.

[0149] An uncertainty metric (e.g., a degree of uncertainty) may have a validity associated with such uncertainty metric. Examples of validity may include one or more of: an area validity, where it may be determined (e.g., by the WTRU) that the uncertainty metric of the target WTRU and / or anchor WTRU may be valid within an area (e.g., a cell ID); and a time validity, where it may be determined (e.g., by the WTRU) that the uncertainty metric may have an expiration time. A timer may be started and it may be determined (e.g., by the WTRU) to update the uncertainty metric (e.g., when the timer expires).

[0150] In an example, when the uncertainty metric associated with absolute positioning is invalid, it can be determined (e.g., by the WTRU) to update the uncertainty metric in accordance with one or more of the following: if a default positioning method (e.g., GNSS / GPS-based positioning) is configured (e.g., by the network), the default positioning method can be executed (e.g., by the WTRU) and the uncertainty metric associated with the positioning method can be obtained; and, if no default positioning method is configured, a request can be transmitted (e.g., by the WTRU to the network) to initiate positioning.

[0151] A quality determination (eg, WTRU-based / based on the WTRU) of the anchor WTRU may be made (eg, by the target WTRU).

[0152] In an example, a request for positioning may be transmitted (e.g., by a WTRU to a network and / or an anchor WTRU). The network and / or the anchor WTRU may not be aware of the accuracy requirements of the target WTRU because the request may originate from the target WTRU. A list of anchor WTRUs that may be available for positioning (e.g., to the target WTRU) may be provided (e.g., by the network). The request may be responded to (e.g., by the anchor WTRU) and assistance information (e.g., SL-PRS configuration information, absolute positioning, uncertainty metrics associated with absolute positioning) may be transmitted (e.g., by the anchor WTRU to the target WTRU). The list of anchor WTRUs may be received (e.g., by the target WTRU from the network) based on a priori knowledge (e.g., the network's a priori knowledge of the location or approximate location of the target WTRU).

[0153] The selection of the anchor WTRU may be optimized.

[0154] The target WTRU may determine the anchor WTRU based on the category to which the anchor WTRU belongs and / or the priority level associated with the category, wherein the characteristics of the location information regarding the anchor WTRU may be categorized.

[0155] If the target WTRU is out of coverage, the WTRU may determine the anchor WTRU based on the coverage status of the anchor WTRU and / or the manner in which the location of the anchor WTRU is determined. In an example, the target WTRU may be configured by the network (e.g., gNB, LMF) or a peer WTRU (e.g., a WTRU with LMF capability) with a priority level associated with characteristics of the location information of the anchor WTRU. In an example, the WTRU may select the anchor WTRU based on the priority level. The WTRU may be pre-configured with a list of categories by the network (e.g., gNB, LMF) or a peer WTRU (e.g., a WTRU with LMF capability), where the categories may consist of characteristics of the anchor WTRU location information. The priority level may be associated with the category. The target WTRU may determine the priority level of the category based on the configuration from the network / peer WTRU (e.g., via LPP, RRC, MAC-CE, DCI).

[0156] In an example, an anchor WTRU may belong to one or more of the following example categories.

[0157] Category 1: The anchor WTRU is in coverage, its position is determined via GNSS, and its position is verified by the network. Category 2: The anchor WTRU is out of coverage, its position is determined via GNSS, and its position is verified by the network. A roadside unit or a positioning reference unit may belong to this category. Category 3: The anchor WTRU is in coverage, its position is determined via a RAT-dependent positioning method (e.g., DL-TDOA, RTT, DL-AoD, UL-AoA, UL-TDOA), and its position is verified by the network. Category 4: The anchor WTRU is in coverage, its position is determined via GNSS, and its position is not verified by the network. Category 5: The anchor WTRU is in coverage, its position is determined via a RAT-dependent positioning method (e.g., DL-TDOA, RTT, DL-AoD, UL-AoA, UL-TDOA), and its position is not verified by the network. Category 6: The anchor WTRU is out of coverage, its position is determined via GNSS, and its position is not verified by the network. Category 7: The anchor WTRU is out of coverage, its location is determined via a RAT-dependent positioning method, and its location is not verified by the network.

[0158] Category 1 may be associated with a higher priority than categories 2-7. Category 7 may be associated with the lowest priority (e.g., lower than categories 1-6). If, via the discovery process, the target WTRU discovers more than one anchor WTRU, the target WTRU may determine the category of the anchor WTRUs and determine a subset of WTRUs based on the priority associated with the category. In an example, if the target WTRU is out of coverage, the WTRU may determine that four anchor WTRUs are (e.g., required) for the positioning method based on the determined positioning method (e.g., via configuration, default / current configuration, hard-coded in the specification). The target WTRU may discover seven anchor WTRUs, of which two WTRUs belong to category 1, one WTRU belongs to category 3, one WTRU belongs to category 4, two WTRUs belong to category 6, and one WTRU belongs to category 7. If the priority levels are associated in descending order with respect to the category number (e.g., category 1 has the highest priority and category 7 has the lowest priority), the WTRU may determine to select two WTRUs in category 1, one WTRU in category 3, and one WTRU in category 4.

[0159] If the target WTRU selects (eg, needs to select) an anchor WTRU from the same category, the WTRU may determine the anchor WTRU based on the anchor WTRU ID (eg, select the anchor WTRU starting with the smallest WTRU ID). The WTRU may select the anchor WTRU based on an indication from the network.

[0160] A WTRU may discover potential anchor WTRUs based on one or more of the following.

[0161] The list of anchor WTRUs may be provided by the network or a peer WTRU (e.g., a WTRU with LMF capability) via unicast / multicast / broadcast. In an example, the target WTRU may provide its location (e.g., cell / area ID, location estimated by GNSS or RAT-related positioning methods) to the network, and the WTRU may receive a list of anchor WTRUs within a threshold from the target WTRU's reported location.

[0162] The discovery procedure may be performed by the target WTRU.In an example, the target WTRU may perform a discovery procedure and identify the anchor WTRU using location information (eg, coordinates of the anchor WTRU, cell / area ID of the cell / area to which the anchor WTRU belongs).

[0163] The WTRU may determine at least one of the following from the discovered / configured anchor WTRU (eg, via higher layer messages such as RRC, SCI, SL MAC-CE, NAS messages, SLPP messages).

[0164] The WTRU may determine the WTRU ID of the anchor WTRU. The WTRU may determine the location information of the anchor WTRU (e.g., WTRU coordinates according to the GCS / LCS, the cell / area ID / index in which the anchor WTRU is located). The WTRU may determine the uncertainty of the location information of the anchor WTRU. The WTRU may determine the positioning method used to determine the location information of the anchor WTRU. The WTRU may determine whether the location information of the anchor WTRU is verified by the network. In an example, the anchor WTRU may need to report its location and / or measurement results to the network to verify its location. An indicator may be used to indicate whether the location of the anchor WTRU is verified (e.g., indicator = 1) or not verified (e.g., indicator = 0).

[0165] The WTRU may determine whether the location information of the anchor WTRU has been determined based on a verified location or a partially verified location, where the partial verification may be represented by a number (e.g., 50% verified, 100% verified, where the percentage may be determined based on the positioning method and / or based on how many WTRUs with verified locations have been used for positioning). In an example, using Figure 3 In the scenario shown, if the position of WTRU_E 312 (determined by GNSS 309) is verified by the network, and the position of WTRU_D 310 (determined by relative positioning) is not verified by the network, then the target WTRU 308 may determine that the position of Anchor_B 304 is partially verified. Figure 3 In the scenario shown, if the locations of WTRU_E 312 and WTRU_D 310 are verified by the network, the target WTRU 308 may determine that the location of Anchor_B 304 is determined based on the verified location. If the target WTRU 308 determines that Anchor_B 304 does not need to perform verification with the network based on an indication / configuration from the network, the location of Anchor_B 304 may be verified. If the location of the anchor WTRU is determined based on a mix of anchor WTRUs whose locations are verified or not verified, the target WTRU may determine that the location of the anchor WTRU is partially verified. An indicator may be used to indicate whether the location of the anchor WTRU is determined based on a verified WTRU (e.g., indicator = 1) or not based on a verified WTRU (e.g., indicator = 0).

[0166] The WTRU may determine the coverage status of the anchor WTRU (eg, in coverage, out of coverage). The WTRU may determine the degree / level of uncertainty of the location information of the anchor WTRU.

[0167] Whether the position of the anchor WTRU for a RAT-dependent positioning method is verified may depend on whether a WTRU-assisted positioning method or a WTRU-based positioning method is used by the network / anchor WTRU. In an example, if the anchor WTRU performs measurements (e.g., RSTD, ToA, AoA, AoD) on the DL PRS and reports the measurements to the network, the network may determine the position of the anchor WTRU and the determined position may be verified by the network. If the anchor WTRU performs a WTRU-based positioning method, the anchor WTRU may need to transmit the determined position and corresponding measurements (e.g., measurements performed on the received PRS) to the network for verification. This category may include information about whether a WTRU-based positioning method (e.g., WTRU-based DL-TDOA, WTRU-based DL-AoD) or a WTRU-assisted positioning method (e.g., WTRU-assisted DL-TDOA, WTRU-assisted DL-AoD, RTT, UL-AoA, UL-TDOA) is performed to determine the WTRU's position.

[0168] In an example, the priority level associated with a category may depend on the coverage status of the target WTRU. If the target WTRU is within coverage, category 3 may have a higher priority than category 2, as described herein.

[0169] In the categories described herein, the WTRU location information may not be verified by the network. Information on whether verification on the WTRU location is performed may be omitted from the categories.

[0170] The determination of the WTRU location in the above categories (e.g., categories where the WTRU location information is not verified, and / or categories where the anchor / target WTRU location is to be determined) may be replaced by accuracy (e.g., error range in the location estimate expressed in distance units such as meters, standard deviation of the location estimate, variance of the location estimate). In addition to the information elements described in the categories described herein, the categories may also include accuracy information.

[0171]

[0066] Among the categories described herein, mobility of an anchor WTRU may be included (eg, an anchor may be mobile or fixed).

[0172] A category can consist of one or more of the following information.

[0173] The category may include the uncertainty of the location information of the anchor WTRU.The category may include the positioning method used to determine the location information (eg, WTRU-assisted / WTRU-based).

[0174] The category may include whether the location information of the anchor WTRU is verified by the network / entity (e.g., an external location server). The anchor WTRU may report its location and / or measurements to the network to verify its location. An indicator may be used to indicate whether the location of the anchor WTRU is verified (e.g., indicator = 1) or not verified (e.g., indicator = 0).

[0175] The category may include whether the location information of the anchor WTRU has been determined based on a verified location or a partially verified location. Partial verification may be represented by a number (e.g., 50% verified, 100% verified; the percentage may be determined based on the positioning method and how many WTRUs with verified locations have been used in positioning). In the example, using Figure 3 In the example shown, if the position of WTRU_E (determined by GNSS) is verified by the network, and the position of WTRU_D (determined by relative positioning) is not verified by the network, then the target WTRU may determine that the position of Anchor_B is partially verified. Figure 2 In the scenario shown, if the locations of WTRU_E and WTRU_D are verified by the network, the target WTRU may determine that the location of Anchor_B is determined based on the verified locations. If the target WTRU determines that Anchor_B does not perform verification with the network based on an indication / configuration from the network, the location of Anchor_B may be verified. If the location of the anchor WTRU is determined based on a mix of one or more anchor WTRUs whose locations are verified and not verified, the target WTRU may determine that the location of the anchor WTRU is partially verified. An indicator may be used to indicate whether the location of the anchor WTRU is determined based on a verified WTRU (e.g., indicator = 1) or not based on a verified WTRU (e.g., indicator = 0).

[0176] The category may include the coverage state of the anchor WTRU (e.g., in coverage, out of coverage). The category may include the degree / grade of uncertainty. The category may include the mobility state (mobile or fixed). The category may include the type of WTRU (e.g., PRU / RSU / WTRU with LMF capability).

[0177] Examples may include the following. The WTRU may be pre-configured with a category list for an anchor WTRU, where the categories in the category list may be associated with priority levels. The WTRU may be configured with a positioning method (e.g., SL-TDOA) from the network. Via a discovery process, the WTRU may determine the anchor WTRU. The WTRU may determine the required number of anchor WTRUs for the positioning method. The anchor WTRU may be selected in descending order of priority level based on the category to which the anchor WTRU belongs (e.g., an anchor WTRU in a category with a higher priority may be selected). The WTRU may make measurements on the SL-PRS sent by the anchor WTRU, and the WTRU may report the selected anchor WTRU and the measurements to the network.

[0178] A determination may be made (eg, by a target WTRU) based on conditions to reset or improve uncertainty associated with an absolute positioning (eg, of the target WTRU).

[0179] Uncertainty can be reduced via the default positioning method.

[0180] In an example, a determination may be made (e.g., by a target WTRU) to reduce uncertainty associated with positioning (e.g., of the WTRU) if one or more of the following are satisfied: the uncertainty associated with absolute positioning (e.g., of the target WTRU) may be above a preconfigured threshold; and / or an indication may be received (e.g., by the target WTRU from the network) to improve the uncertainty.

[0181] If one or more of the foregoing are met, a determination may be made (e.g., by the WTRU) to perform a default positioning method (e.g., GNSS), and an absolute position (e.g., of the WTRU) and an associated uncertainty metric may be determined (e.g., by the WTRU). If the default positioning method does not reduce the uncertainty associated with the absolute position, a request may be transmitted (e.g., by the WTRU to the network) to remove the WTRU from the anchor WTRU list.

[0182] If one or more of the following are met, a determination may be made (e.g., by the target WTRU) to reduce a degree of uncertainty in the positioning (e.g., of the target WTRU). In an example, a degree of uncertainty or error level associated with the absolute positioning of the target WTRU may be above a preconfigured threshold. In an example, an indication may be received (e.g., by the target WTRU from a network) to reduce the degree of uncertainty (e.g., or error level).

[0183] If one or more of the foregoing are met, a determination may be made (e.g., by the WTRU) to perform a default positioning method (e.g., GNSS / GPS) or (e.g., any) positioning method that does not rely on an anchor WTRU. After performing the positioning method, the degree of uncertainty may be set to zero (0), or the error level may be reset (e.g., by the WTRU) to a value associated with the positioning method.

[0184] Uncertainty reduction can be performed on demand.

[0185] In an example, if the target WTRU is within coverage, if one or more of the foregoing are satisfied, then a request may be transmitted (e.g., to the network and / or anchor WTRU) to configure a set of anchor WTRUs or anchor WTRUs (e.g., for SL positioning) (e.g., by the WTRU). The set ID and / or WTRU ID may be indicated (e.g., by the WTRU) in the request.

[0186] The set ID and / or WTRU ID may be indicated (e.g., by the target WTRU to the network). If there are no more sets of WTRUs or more WTRUs to request, then a determination may be made (e.g., by the target WTRU) to perform a default positioning method (e.g., GNSS / GPS positioning).

[0187] In an example, if there are no (e.g., no more) WTRU groups or WTRUs to request, a request may be transmitted (e.g., from the target WTRU to the network and / or anchor WTRU) for another set of SL-PRS configurations (e.g., wider bandwidth, shorter periodicity, a larger number of slots containing SL-PRS). If a new set of configurations is received (e.g., by the target WTRU from the anchor WTRU and / or the network), a determination may be made (e.g., by the target WTRU) to perform a positioning method (e.g., utilizing the initial set of anchor WTRUs).

[0188] In an example, if the target WTRU is out of coverage, the WTRU may transmit another positioning request to a different WTRU. If the target WTRU cannot find any more WTRUs within a preconfigured time window, the target WTRU may determine to perform a default positioning method (e.g., GNSS / GPS positioning). In an example, the target WTRU may start a timer and search for different anchor WTRUs until the timer expires. The WTRU may receive an expiration time of the timer.

[0189] The positioning method used may be reported. In an example, if requested by the network or a peer WTRU (e.g., an LMF-capable WTRU), the target WTRU may report the positioning method used to determine its position (e.g., the position of the target WTRU) to the network (e.g., LMF, gNB) or a peer WTRU (e.g., an LMF-capable WTRU). If the target WTRU determines to use GNSS to determine its position, the target WTRU may indicate to the network that GNSS is used to determine the position of the target WTRU.

[0190] An uncertainty associated with the WTRU's location may be determined. In an example, a WTRU (e.g., a target WTRU) may determine the uncertainty associated with the WTRU's location based on a function of the configuration and / or assistance data associated with the anchor WTRU (e.g., the uncertainty associated with the location information of the anchor WTRU). The WTRU may determine the uncertainty of its location based on the uncertainty of the location information of the anchor WTRU, the assistance data, measurements (e.g., RSRP, RSTD, ToA, WTRU Rx-Tx time), the number of anchor WTRUs, channel conditions (e.g., LOS indicator), and / or the positioning method used to determine the WTRU's location. If a positioning method like TDOA is used, the uncertainty metric of the determined WTRU's location may be an average of the uncertainty metrics of the anchor WTRUs. If a positioning method like RTT is used, the uncertainty metric of the determined WTRU's location may be the output of a non-linear function of the uncertainty metrics of the anchor WTRUs.

[0191] Parameters associated with the uncertainty metric can be used to determine whether a quantity is below or above a threshold. As described herein, uncertainty below a threshold can refer to at least one of the following: the error level is below a configured threshold; the degree of uncertainty is below a configured threshold; and / or the maximum and / or minimum value of the uncertainty metric is below a configured threshold. An example of uncertainty below a configured threshold can be as follows: if the uncertainty metric is defined by a range (e.g., + / - 5m), then the absolute value of the maximum value (e.g., 5m), the minimum value (e.g., -5m), or the maximum value of the range (e.g., 5m) is below the configured threshold.

[0192] A positioning method may be determined based on uncertainty. In an example, the WTRU may determine an anchor WTRU to be used for a positioning method via a discovery process. The WTRU may receive assistance information (e.g., uncertainty metrics) from the anchor WTRU. Based on the uncertainty metrics of the anchor WTRU, the WTRU may determine the uncertainty metrics of the configured positioning methods (e.g., RAT-dependent positioning methods such as TDOA, RTT, AoA, AoD positioning methods, or RAT-independent positioning methods such as GNSS, sensor-based, wifi-based positioning). Based on the determined uncertainty metrics for the positioning methods, the WTRU may determine to use a positioning method with the least or minimum uncertainty metrics. In an example, the WTRU may determine the uncertainty metrics for the positioning method based on the uncertainty of the position information of the anchor WTRU, the assistance data, and / or the number of anchor WTRUs.

[0193] In an example, if the WTRU is configured with a TDOA positioning method and a GNSS, the WTRU may determine an uncertainty metric associated with the TDOA positioning method based on the uncertainty metric of the position of the anchor WTRU. The WTRU may determine an uncertainty metric associated with the GNSS positioning method. If the uncertainty metric associated with the TDOA method is less than the uncertainty metric associated with the GNSS positioning method, the WTRU may select the TDOA positioning method.

[0194] After the WTRU determines a positioning method, the WTRU may determine an uncertainty metric associated with the determined WTRU location information.

[0195] In an example, the number of anchor WTRUs discovered for a positioning method may be greater than the number of anchor WTRUs for the positioning method (e.g., a required number). The number of anchor WTRUs for the positioning method (e.g., a required number) may be configured by the network or a peer WTRU (e.g., a LMF-capable WTRU). In an example, if the number of anchor WTRUs discovered is greater than the number of anchor WTRUs for the positioning method (e.g., a required number) (e.g., N), the WTRU (e.g., a target WTRU) may determine to select the N anchor WTRUs based on at least one of the following metrics: for example, a priority level associated with the anchor WTRUs (e.g., high, low, medium, a number between 0 and 1), a distance of the anchor WTRUs relative to the WTRU, an RSRP of a signal (e.g., SL-PRS) sent from the anchor WTRUs (e.g., selecting the N anchor WTRUs with the N highest RSRP values), a coverage status (e.g., selecting an anchor WTRU in coverage over selecting an anchor WTRU out of coverage), an anchor WTRU with a verified location (where the location is determined by the network or a peer WTRU). U verification (e.g., a server WTRU, where the WTRU can act as a LMF by configuring SL-PRS to other WTRUs based on measurements to determine location information of other WTRUs, receiving location information from other WTRUs, etc., the server WTRU can configure SL-PRS to the WTRU based on pre-configured SL-PRS, etc.), an anchor WTRU verified or indicated by a network or peer WTRU (e.g., a server WTRU), and / or a mobility state (e.g., selecting an anchor WTRU with fixed or low mobility is preferred over selecting an anchor WTRU with high mobility). In an example, a WTRU (e.g., a target WTRU) may transmit an identity (e.g., RNTI, WTRU ID) of a discovered anchor WTRU to the network or peer WTRU (e.g., a server WTRU), and request an indication of N anchor WTRUs from the network or peer WTRU.

[0196] The WTRU may include determination of a default positioning method. The default positioning method may be incorporated into the target WTRU. The target WTRU may be configured to select one or more anchor WTRUs from the candidate anchor WTRUs. The selection criteria may be based on an uncertainty metric from the selected anchor WTRU being below an error threshold.

[0197] In an example, a configuration (e.g., a default positioning method, an SL positioning method, a threshold, or N (e.g., a desired number of anchor WTRUs) may be received (e.g., by the WTRU from a network). Configuration information for the configuration may indicate a default positioning method, an error threshold, and / or a threshold number of anchor WTRUs. A target WTRU WTRU may be enabled to determine candidate anchor WTRUs and corresponding uncertainty metrics from the candidate anchor WTRUs. The target WTRU may determine the anchor WTRU based on a response to a positioning request. The target WTRU may receive a PRS configuration and error information (e.g., position uncertainty) from the anchor WTRU. The target WTRU may use the PRC position uncertainty information to determine the target WTRU absolute position and the target WTRU uncertainty metric.

[0198] If the selected anchor WTRU is above a threshold number of anchor WTRUs, the target WTRU may use the sidelink positioning method to determine the target WTRU absolute location. Under these conditions, the target WTRU uncertainty metric may be associated with the uncertainty associated with the selected anchor WTRU and the uncertainty associated with the sidelink positioning method.

[0199] When the selected anchor WTRUs are equal to or higher than the threshold number of anchor WTRUs, the processor may determine the target WTRU absolute location using a combination of the sidelink positioning method and the default positioning method.

[0200] If the associated position uncertainty is below a preconfigured error threshold, the WTRU may select an anchor WTRU. If no N anchor WTRUs are found (e.g., by the WTRU), then it may be determined (e.g., by the WTRU) to use a default positioning method (e.g., GNSS) to determine (e.g., the WTRU's) absolute position.

[0201] If at least N anchor WTRUs are found (e.g., by the WTRU), a pre-configured positioning method may be performed and an absolute positioning may be determined. The cumulative uncertainty may be determined (e.g., by the WTRU) based on one or more of the following. If positioning is determined (e.g., by the WTRU) without using an anchor WTRU (e.g., GNSS), the cumulative error may be reset to the corresponding positioning error (e.g., GNSS); In the case where the target WTRU absolute positioning is determined using a default positioning method, the target WTRU may reset the target WTRU uncertainty metric to the uncertainty associated with the default positioning method.

[0202] If the position is determined using (eg, by) an anchor WTRU, errors may accumulate. Assuming the target WTRU absolute position is determined using a sidelink positioning method, the WTRU may accumulate uncertainty metrics based on the uncertainty metrics associated with the selected anchor WTRU.

[0203] If the WTRU is within coverage, a report may be transmitted (e.g., by the WTRU to the network) containing the absolute position, the associated uncertainty measure, and information related to the anchor WTRU for SL positioning (e.g., WTRU ID) (e.g., if the WTRU enters coverage or the WTRU is within coverage). The target WTRU may be configured to send an indication of the target WTRU absolute position and the target WTRU uncertainty measure to the network node. When the target WTRU enters network coverage, the target WTRU may send information related to the selected anchor WTRU for positioning to the network node. The information sent may include an identification of the selected anchor WTRU.

[0204] Different uncertainty metrics may be associated with the determination of the anchor WTRU.

[0205] In an example, a PRS configuration associated with an anchor WTRU may be received (e.g., by the WTRU) along with associated error information (e.g., location uncertainty, degree of uncertainty), a first error threshold and a second error threshold, N (a desired number of anchor WTRUs), and a positioning method (e.g., from a network (e.g., LMF, gNB)). A first group of anchor WTRUs may be received (e.g., by the WTRU from the network). A prioritized list of uncertainties (e.g., degree of uncertainty higher than location uncertainty) may be received (e.g., by the WTRU). Based on the first group of anchor WTRUs, a second group may be determined (e.g., by the WTRU) to include WTRUs having a degree of uncertainty (e.g., below a first threshold). If the number of WTRUs in the second group is below N, a determination may be made (e.g., by the WTRU) to perform a default positioning method (e.g., GNSS, Uu based positioning). Based on the second group of anchor WTRUs, a third group may be determined (e.g., by the WTRU) to include WTRUs having an uncertainty below a second threshold. If the number of WTRUs in the third group is below N, a determination may be made (e.g., by the WTRU) to perform a default positioning method (e.g., GNSS, Uu based positioning). A SL positioning method may be performed and an absolute position of the WTRU may be determined (e.g., by the WTRU). An uncertainty metric associated with the absolute position may be determined (e.g., by the WTRU). If the WTRU is within coverage, a report may be transmitted (e.g., by the WTRU) containing the absolute position and the associated uncertainty metric and a set of anchor WTRUs (e.g., WTRU IDs) used to determine the position of the WTRU.

[0206] Measurements and uncertainty metrics may be associated with the determination of the anchor WTRU.

[0207] In an example, a request for location information may be received (e.g., by the WTRU from a network). A PRS configuration associated with an anchor WTRU may be received (e.g., by the WTRU) along with associated error information (e.g., a degree of uncertainty), a first error threshold and a second error threshold, N (a desired number of anchor WTRUs), and a positioning method (e.g., from the network (LMF, gNB)). A first set of anchor WTRUs may be received (e.g., by the WTRU from the network). Measurements (e.g., RSRP) related to SL PRSs sent (e.g., from a set of anchor WTRUs) may be made (e.g., by the WTRU). If the RSRP measured on the SL-PRS for the anchor WTRU is above or equal to a first threshold, it may be determined (e.g., by the WTRU) to use the anchor WTRU for SL positioning. If the RSRP measured on the SL-PRS for the anchor WTRU is below a first threshold and an uncertainty metric associated with the absolute positioning of the anchor WTRU is below a second threshold, it may be determined (e.g., by the WTRU) to use the anchor WTRU for SL positioning. The positioning may be determined (e.g., by the WTRU) based on the SL positioning. If more than one anchor WTRU is used for SL positioning, the uncertainty level associated with the absolute positioning may be determined (e.g., by the WTRU) based on the maximum uncertainty level (e.g., among the anchor WTRUs). A set of anchor WTRUs (e.g., WTRU IDs) used to determine the positioning of the WTRU may be reported (e.g., by the WTRU) along with the WTRU's absolute positioning and associated uncertainty metrics (e.g., uncertainty levels).

[0208] Figure 5 An example signal flow diagram is illustrated that may be applied to determine an anchor WTRU based on measurements and uncertainty metrics.

[0209] The out of coverage scenario may be associated with the determination of the anchor WTRU.

[0210] Figure 6 An example of selection of an anchor WTRU for an out of coverage scenario is illustrated.

[0211] In an example, a positioning method and selection criteria (e.g., a degree of uncertainty below a threshold) for an anchor WTRU may be pre-configured (e.g., on a target WTRU). An anchor WTRU may be discovered (e.g., by the target WTRU) and a positioning request may be transmitted (e.g., by the target WTRU). Assistance information may be received (e.g., by the target WTRU from the anchor WTRU). A determination may be made (e.g., by the target WTRU) to use an anchor WTRU based on a degree of uncertainty associated with an absolute positioning (e.g., of the anchor WTRU). If the degree of uncertainty is above a threshold, a different anchor WTRU may be searched (e.g., by the target WTRU) until a search timer expires. A notification of the selection may be transmitted (e.g., by the target WTRU to the anchor WTRU). Resource allocation information (e.g., for SL-PRS) (e.g., a Mode 2 allocation indicating time and / or frequency resources for SL-PRS transmission) may be received (e.g., by the target WTRU from the anchor WTRU). Measurements (e.g., related to SL-PRS) may be made (e.g., by the target WTRU). The absolute positioning of the target WTRU may be determined (e.g., by the target WTRU) based on measurements (e.g., measurements made on the SL-PRS transmitted by the anchor WTRU). An uncertainty metric based on an uncertainty metric associated with the absolute positioning of the anchor WTRU may be determined (e.g., by the target WTRU). If the target WTRU enters coverage, the absolute positioning (e.g., of the target WTRU) and the associated uncertainty metric may be returned along with information related to the anchor WTRU for SL positioning.

[0212] Although the features and elements are described above in specific combinations, it will be understood by those of ordinary skill in the art that each feature or element may be used alone or in any combination with other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (sent via a wired or wireless connection) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media (such as built-in hard disks and removable disks), magneto-optical media, and optical media (such as CD-ROM disks and digital versatile disks (DVDs)). A processor associated with the software may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host.

Claims

1. A target wireless transmit / receive unit (WTRU), the target wireless transmit / receive unit (WTRU) comprising a processor: The processor is configured to: selecting one or more anchor WTRUs from the candidate anchor WTRUs based on an uncertainty metric from the selected anchor WTRU being below an error threshold; determining a target WTRU absolute position and a target WTRU uncertainty metric, wherein the processor is configured to: In the event that the selected anchor WTRU is below a threshold number of anchor WTRUs, using a default positioning method to determine the absolute position of the target WTRU, and determining the target WTRU uncertainty metric, wherein the target WTRU uncertainty metric comprises any of an uncertainty of the target WTRU or a degree of uncertainty of the target WTRU; and An indication of the target WTRU absolute position and the target WTRU uncertainty measure is sent to a network node.

2. The target WTRU of claim 1 , wherein in a case where the selected anchor WTRU is below the threshold number of anchor WTRUs, the target WTRU uncertainty metric is associated with an uncertainty of the default positioning method.

3. The target WTRU of claim 1 , wherein in a case where the selected anchor WTRU is above the threshold number of anchor WTRUs, the processor is configured to determine the absolute location of the target WTRU using a sidelink positioning method.

4. The target WTRU of claim 3, wherein in a case where the selected anchor WTRU is above the threshold number of anchor WTRUs, the target WTRU uncertainty metric is associated with an uncertainty associated with the selected anchor WTRU and an uncertainty associated with the sidelink positioning method.

5. The target WTRU of claim 3, wherein in a case where the selected anchor WTRU is equal to or higher than the threshold number of anchor WTRUs, the processor is configured to: The target WTRU absolute location is determined using a combination of the sidelink positioning method and the default positioning method.

6. The target WTRU of claim 3, wherein the processor is further configured to: In determining the absolute positioning of the target WTRU using the sidelink positioning method, the uncertainty metric is accumulated based on a plurality of uncertainty metrics associated with each of the selected anchor WTRUs.

7. The target WTRU of claim 1 , wherein the processor is further configured to: In the event that the target WTRU absolute position is determined using the default positioning method, the target WTRU uncertainty metric is reset to the uncertainty associated with the default positioning method.

8. The target WTRU of claim 1 , wherein the processor is further configured to: In case the target WTRU enters network coverage, information related to the selected anchor WTRU for positioning is sent to the network node, wherein the information includes an identity of the selected anchor WTRU.

9. The target WTRU of claim 1 , wherein the processor is further configured to: receiving configuration information indicating any one of the default positioning method, the error threshold, or the threshold number of anchor WTRUs; and The candidate anchor WTRUs and a corresponding uncertainty metric for each of the candidate anchor WTRUs are determined.

10. A method for a target wireless transmit / receive unit (WTRU), the method comprising: selecting one or more anchor WTRUs from the candidate anchor WTRUs based on an uncertainty metric from the selected anchor WTRU being below an error threshold; determining a target WTRU absolute position and a target WTRU uncertainty measure, wherein the method further comprises: In the event that the selected anchor WTRU is below a threshold number of anchor WTRUs, using a default positioning method to determine the absolute position of the target WTRU, and determining the target WTRU uncertainty metric, wherein the target WTRU uncertainty metric comprises any of an uncertainty of the target WTRU or a degree of uncertainty of the target WTRU; as well as An indication of the target WTRU absolute position and the target WTRU uncertainty measure is sent to a network node.

11. The method of claim 10, wherein in a case where the selected anchor WTRU is below the threshold number of anchor WTRUs, the target WTRU uncertainty metric is associated with an uncertainty of the default positioning method.

12. The method of claim 10, wherein in a case where the selected anchor WTRU is above the threshold number of anchor WTRUs, the method further comprises determining the target WTRU absolute location using a sidelink positioning method.

13. The method of claim 12, wherein in a case where the selected anchor WTRU is above the threshold number of anchor WTRUs, the target WTRU uncertainty metric is associated with an uncertainty associated with the selected anchor WTRU and an uncertainty associated with the sidelink positioning method.

14. The method of claim 12, wherein in a case where the selected anchor WTRU is equal to or higher than the threshold number of anchor WTRUs, the method further comprises: The target WTRU absolute location is determined using a combination of the sidelink positioning method and the default positioning method.

15. The method according to claim 12, wherein the method further comprises: In determining the absolute positioning of the target WTRU using the sidelink positioning method, the uncertainty metric is accumulated based on a plurality of uncertainty metrics associated with each of the selected anchor WTRUs.

16. The method according to claim 10, wherein the method further comprises: In the event that the target WTRU absolute position is determined using the default positioning method, the target WTRU uncertainty metric is reset to the uncertainty associated with the default positioning method.

17. The method according to claim 10, wherein the method further comprises: In case the target WTRU enters network coverage, information related to the selected anchor WTRU for positioning is sent to the network node, wherein the information includes an identity of the selected anchor WTRU.

18. The method according to claim 10, wherein the method further comprises: receiving configuration information indicating any one of the default positioning method, the error threshold, or the threshold number of anchor WTRUs; as well as The candidate anchor WTRUs and a corresponding uncertainty metric for each of the candidate anchor WTRUs are determined.

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