Prevention of Error Propagation for Sidelink Positioning

Abstract

Systems, methods, and means 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 uncertainty metrics from the one or more anchor WTRUs being below an error threshold. The target WTRU may determine a target WTRU absolute location and a target WTRU uncertainty metric. The target WTRU may determine the target WTRU absolute location using a default positioning method, provided that the selected anchor WTRU is below a threshold number of anchor WTRUs. The target WTRU may determine a target WTRU uncertainty metric, which may include the target WTRU's uncertainty and / or the degree of the target WTRU's uncertainty. The target WTRU may transmit an indication of the target WTRU absolute location and the target WTRU uncertainty metric to a network node.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 395,966, filed August 8, 2022, U.S. Provisional Patent Application No. 63 / 445,376, filed February 14, 2023, and U.S. Provisional Patent Application No. 63 / 465,092, filed May 9, 2023, the contents of which are incorporated herein by reference. [Background technology]

[0002] 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). Previous (traditional) generations of mobile communications RAT may be, for example, fourth generation (4G) long term evolution (LTE). Summary of the Invention

[0003] Systems, methods, and means 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 uncertainty metrics from the one or more anchor WTRUs being below an error threshold. The target WTRU may determine a target WTRU absolute location and a target WTRU uncertainty metric. The target WTRU may determine the target WTRU absolute location using a default positioning method, provided that the selected anchor WTRU is below a threshold number of anchor WTRUs. The target WTRU may determine a target WTRU uncertainty metric, which may include the target WTRU's uncertainty and / or the degree of the target WTRU's uncertainty. The target WTRU may transmit an indication of the target WTRU absolute location and the target WTRU uncertainty metric to a network node.

[0004] If the selected anchor WTRU is below a threshold number of anchor WTRUs, the target WTRU uncertainty metric may be related to the uncertainty of the default positioning method.

[0005] If the selected anchor WTRU exceeds a threshold number of anchor WTRUs, the target WTRU may determine the target WTRU absolute location using a sidelink positioning method. If the selected anchor WTRU exceeds a threshold number of anchor WTRUs, the target WTRU uncertainty metric may be related to the uncertainty associated with the selected anchor WTRU and the uncertainty associated with the sidelink positioning method.

[0006] If the selected anchor WTRU is equal to or greater than the threshold number of anchor WTRUs, the target WTRU may determine the target WTRU absolute location using a combination of the sidelink positioning method and the default positioning method.

[0007] The target WTRU may accumulate an uncertainty metric based on the uncertainty metric associated with each of the selected anchor WTRUs when the target WTRU absolute position is determined using a sidelink positioning method.

[0008] The target WTRU may reset the target WTRU uncertainty metric to the uncertainty associated with the default positioning method if the target WTRU absolute position is determined using the default positioning method.

[0009] The target WTRU may send information related to the selected anchor WTRU to be used for positioning to the network node when the target WTRU enters network coverage. The information may include the identity of the selected anchor WTRU.

[0010] 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 respective uncertainty metrics from each of the candidate anchor WTRUs.

[0011] Systems, methods, and means for preventing error propagation for sidelink positioning are disclosed. A wireless transmit / receive unit (WTRU) may determine an anchor WTRU through a discovery procedure. The WTRU may select multiple anchor WTRUs for positioning from the determined anchor WTRU, which may be determined by ranking the determined anchor WTRUs in descending order based on their respective priority levels. The respective priority levels of the determined anchor WTRUs may correspond to respective categories associated with the determined anchor WTRU. The WTRU may receive respective positioning reference signals from the selected anchor WTRU. 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 the network.

[0012] The uncertainty metric for the configured positioning method may be further based on location 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.

[0013] The configured positioning methods may include: 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.

[0014] Systems, methods, and means 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 the anchor WTRU may be determined based on the location uncertainty information. In an example, the selection of the anchor WTRU may be based on the location uncertainty information being below a preconfigured uncertainty threshold. An accumulated uncertainty associated with the WTRU may be determined. In an example, the accumulated uncertainty may be a corresponding positioning error based on a determination that the WTRU determined the location of the WTRU without using the anchor WTRU. In an example, the accumulated uncertainty may be accumulated based on a determination that the WTRU determined the position of the WTRU using the anchor WTRU.

[0015] The WTRU may determine an anchor WTRU through a discovery procedure. The WTRU may select multiple anchor WTRUs for positioning from the determined anchor WTRUs. The multiple anchor WTRUs may be determined by ranking 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 respective measurements corresponding to each respective positioning reference signal. The WTRU may report the selected anchor WTRUs and the respective measurements to the network.

[0016] The WTRU may receive the list of anchor WTRUs or may be pre-configured with the list of anchor WTRUs. The list may identify a respective category for each anchor WTRU in the list. Each respective category may be associated with a respective priority.

[0017] The WTRU may receive an indication of a positioning method from the network, and may use the anchor WTRU's decision in the received positioning method.

[0018] A wireless transmit / receive unit (WTRU) may determine an anchor WTRU through a discovery procedure. The WTRU may select a positioning anchor WTRU for a positioning method from the anchor WTRU. The positioning anchor WTRU may be determined in descending order based on a priority level, which may correspond to a category associated with the positioning anchor WTRU. The WTRU may receive position reference signals from the positioning anchor WTRU. The WTRU may determine measurements corresponding to the position reference signals. The WTRU may report the measurements and the positioning anchor WTRU to the network.

[0019] The WTRU may be pre-configured with multiple categories for the positioning anchor WTRU, and each category of the multiple categories may be associated with a priority level. The WTRU may receive a positioning method from the network.

[0020] For positioning, downlink positioning methods, uplink positioning methods, and downlink and uplink positioning methods may be used. Such methods may use signals (e.g., positioning reference signals, sounding reference signals, and sounding reference signals for positioning purposes). The environment may play a role (e.g., a significant role) in measuring the signals and may affect the positioning accuracy. In sidelink (SL) positioning, the location of a WTRU may be determined (e.g., by a target WTRU) based on measurements made on SL position reference signals (SL PRS) transmitted by an anchor WTRU. The location of the target WTRU may be determined (e.g., by the target WTRU) based on the absolute location of the target WTRU and its relative location with respect to the location of the anchor WTRU (e.g., the location of the anchor WTRU).

[0021] The absolute position of a target WTRU (e.g., a WTRU to be positioned) may be determined using the absolute position of an anchor WTRU (e.g., a 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 for accurate positioning).

[0022] The absolute position of the first anchor WTRU may be derived based on the absolute position of the second anchor WTRU, and errors associated with the absolute positions of the first and second anchor WTRUs may propagate to the absolute position of the target WTRU.

[0023] The anchor WTRU may be selected (e.g., by the target WTRU) based on an estimated location uncertainty at the target WTRU (e.g., the target WTRU may determine an estimated location error based on the location error uncertainty of the anchor WTRU measurements (e.g., using reference signal received power (RSRP) and reference signal time difference (RSTD))).

[0024] The location uncertainty information may include an uncertainty metric and / or 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 exceed a preconfigured threshold. If the uncertainty exceeds the preconfigured threshold, it may be decided (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 0).

[0025] A first set of anchor WTRUs may be determined (e.g., by the target WTRU) based on a first metric (e.g., a degree of uncertainty). Among the first set of WTRUs (e.g., anchor WTRUs), the target WTRU may determine a second set of anchor WTRUs based on a second metric (e.g., an uncertainty associated with an absolute position). [Brief explanation of the drawings]

[0026] [Figure 1A] FIG. 1 is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented. [Figure 1B] 1B is a system diagram illustrating an exemplary wireless transmit / receive unit (WTRU) that may be used within the communication system illustrated in FIG. 1A, according to one embodiment. [Figure 1C]1A is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communication system illustrated in FIG. 1A, according to one embodiment. [Figure 1D] 1B is a system diagram illustrating a further exemplary RAN and a further exemplary CN that may be used within the communication system illustrated in FIG. 1A, according to one embodiment. [Figure 2] An example of error propagation is shown below. [Figure 3] 10 shows examples of determining the location of a WTRU with different degrees of uncertainty. [Figure 4] 10 illustrates an example of selecting an anchor WTRU based on the degree of uncertainty. [Figure 5] 10 shows an example signal flow diagram for anchor WTRU determination. [Figure 6] 1 illustrates an example of selecting an anchor WTRU in out-of-coverage cases. DETAILED DESCRIPTION OF THE INVENTION

[0027] Described herein are systems, methods, and means for preventing error propagation for sidelink positioning.

[0028] 1A is a diagram illustrating an example communication system 100 in which one or more disclosed embodiments may be implemented. Communication system 100 may be a multiple-access system that provides content, such as voice, data, video, messaging, broadcasts, etc., to multiple wireless users. Communication system 100 may enable multiple wireless users to access such content through sharing of system resources, including wireless bandwidth. In examples, the communication system 100 may use 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, filter bank multicarrier (FBMC), etc.

[0029] 1A, communications system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RANs 104 / 113, CNs 106 / 115, public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, although it will be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of 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 WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a "station" and / or "STA," may be configured to transmit and / or receive wireless signals and may include user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a mobile phone, a personal digital assistant (PDA), a smartphone, 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, a medical device and application (e.g., for remote surgery), an industrial device and application (e.g., a robot and / or other wireless device operating in an industrial and / or automated processing chain context), a consumer electronics device, a device operating on a commercial wireless network and / or an industrial wireless network, etc. Any of the UEs 102a, 102b, 102c, and 102d may be referred to interchangeably as a WTRU.

[0030] The communications 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 configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communications 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 eNodeB, a Home Node B, a Home eNodeB, a gNB, an NR Node B, a site controller, an access point (AP), a wireless router, etc. Although the base stations 114a, 114b are each depicted as a single element, it will be understood that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0031] The base station 114a may be part of the RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and / or base station 114b may be configured to transmit and / or receive radio signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide wireless service coverage for a particular geographic area, which may be relatively fixed or may change over time. A cell may be further divided into cell sectors. In an example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In one embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and may utilize multiple transceivers per sector of the cell. In an example, beamforming may be used to transmit and / or receive signals in a desired spatial direction.

[0032] 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).

[0033] More specifically, as noted above, the communications system 100 may be a multiple-access system, but may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. In an example, the base station 114a and the WTRUs 102a, 102b, 102c in the RAN 104 / 113 may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 115 / 116 / 117 using wideband CDMA (WCDMA). WCDMA may include communications 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 ​​Uplink Packet Access (HSUPA).

[0034] In one 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), which may establish the air interface 116 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-Advanced Pro (LTE-A Pro).

[0035] In one 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).

[0036] In one 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 jointly implement LTE radio access and NR radio access, e.g., 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 sent to and from multiple types of base stations (e.g., eNBs and gNBs).

[0037] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement a wireless technology 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), GSM EDGE (GERAN), or the like.

[0038] 1A 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 a local area such as a business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, etc. 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 one 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 establish a picocell or a femtocell using a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.). As shown in FIG. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not need to access the Internet 110 through the CN 106 / 115.

[0039] The RAN 104 / 113 may communicate with the CN 106 / 115, which may be any type of network configured to provide voice, data, application, and / or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have various quality of service (QoS) requirements, such as different throughput, latency, error tolerance, reliability, data throughput, and mobility requirements. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, and / or perform high-level security functions such as user authentication. Although not shown in FIG. 1A , it will be understood that the RAN 104 / 113 and / or the CN 106 / 115 may communicate directly or indirectly with other RANs employing 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 communicate with another RAN (not shown) employing GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0040] The CN 106 / 115 may also serve 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 providing 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), user datagram protocol (UDP), and / or the internet protocol (IP) of the TCP / IP Internet protocol suite. The network 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. In an example, the network 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.

[0041] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications 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 over different wireless links). In an example, the WTRU 102c shown in FIG. 1A may be configured to communicate with a base station 114a, which may employ a cellular-based wireless technology, and a base station 114b, which may employ an IEEE 802.2 wireless technology.

[0042] 1B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1B, 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 understood that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0043] The processor 118 may be a general-purpose processor, a special-purpose processor, a conventional processor, a digital signal processor (DSP), multiple 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), a state machine, etc. The processor 118 may perform signal coding, 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. While FIG. 1B depicts the processor 118 and the transceiver 120 as separate components, it will be understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0044] The transmit / receive element 122 may be configured to transmit or receive signals to or from a base station (e.g., base station 114a) over the air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In one embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive, for example, IR signals, UV signals, or visible light signals. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF signals and light signals. It will be understood that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0045] 1B as a single element, 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.

[0046] The transceiver 120 may be configured to modulate signals transmitted by the transmit / receive element 122 and demodulate signals received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as, for example, NR and IEEE 802.11.

[0047] The processor 118 of the WTRU 102 may be coupled to and may receive user-entered 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. Additionally, the processor 118 may access information from and store data in any type of suitable memory, such as non-removable memory 130 and / or removable memory 132. The non-removable memory 130 may include random-access memory (RAM), 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, a secure digital (SD) memory card, etc. In other embodiments, the processor 118 may access information from and store data in memory that is not physically located on the WTRU 102, such as on a server or home computer (not shown).

[0048] The processor 118 may receive power from the power source 134 and may be configured to distribute and / or control the power to other components within the WTRU 102. The power source 134 may be any suitable device for providing power to the WTRU 102. In examples, the power source 134 may include one or more dry batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0049] The processor 118 may also be coupled to a 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 instead of, information from the GPS chipset 136, the WTRU 102 may receive location information from base stations (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 way of any suitable location-determination method while remaining consistent with an embodiment.

[0050] The processor 118 may further be coupled to other peripherals 138, which may include one or more software and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. By way of example, the peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or videos), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, etc. The peripheral device 138 may include one or more sensors, which may be one or more of a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, a direction sensor, a proximity sensor, a temperature sensor, a time sensor, a geolocation sensor, an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0051] The WTRU 102 may include a full-duplex radio where transmission and reception of some or all of the signals associated with a particular subframe (e.g., for both the UL (e.g., for transmission) and downlink (e.g., for reception)) may be parallel and / or simultaneous. The full-duplex radio may include an interference management unit to reduce and or substantially eliminate self-interference through either hardware (e.g., a choke) or signal processing via a processor (e.g., via a separate processor (not shown) or processor 118). In one embodiment, the WTRU 102 may include a half-duplex radio for transmission and reception of either some or all of the signals (e.g., associated with a particular subframe for either the UL (e.g., for transmission) or downlink (e.g., for reception)).

[0052] 1C is a system diagram illustrating the RAN 104 and the CN 106, according to one embodiment. As noted above, the RAN 104 may employ E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also communicate with the CN 106.

[0053] The RAN 104 may include eNodeBs 160a, 160b, and 160c, although it will be understood that the RAN 104 may include any number of eNodeBs while remaining consistent with an embodiment. The eNodeBs 160a, 160b, and 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, and 102c over the air interface 116. In an embodiment, the eNodeBs 160a, 160b, and 160c may implement MIMO technology. Thus, the eNodeB 160a may, for example, use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0054] Each of the eNodeBs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, etc. As shown in FIG. 1C, the eNodeBs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0055] 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. Although each of the foregoing elements is depicted as part of the CN 106, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0056] The MME 162 may be connected to each of the eNodeBs 162a, 162b, 162c in the RAN 104 via an S1 interface and may function as a control node. In an example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, activating / deactivating bearers, selecting a particular serving gateway during initial attach of the WTRUs 102a, 102b, 102c, etc. 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.

[0057] The SGW 164 may be connected to each of the eNodeBs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to and from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions such as anchoring the user plane during inter-eNodeB handovers, triggering paging when DL data is available to the WTRUs 102a, 102b, 102c, and managing and storing the context of the WTRUs 102a, 102b, 102c.

[0058] The SGW 164 may be connected to a 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.

[0059] 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 landline communications devices. In an example, the CN 106 may include or communicate with an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. Additionally, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0060] Although the WTRU is illustrated in FIGS. 1A-1D as a wireless terminal, it is contemplated that in certain representative embodiments, such a terminal may use a wired communication interface (e.g., temporarily or permanently) with the communication network.

[0061] In a representative embodiment, the other network 112 may be a WLAN.

[0062] A WLAN in infrastructure Basic Service Set (BSS) mode may have an access point (AP) of the BSS and one or more stations (STAs) associated with the AP. The AP may have access to or interface with a Distribution System (DS) or another type of wired / wireless network that carries traffic into and / or out of the BSS. Traffic originating from outside the BSS to a STA may arrive through the AP and be delivered to the STA. Traffic originating from a STA to a destination outside the BSS may be sent to the AP to be delivered to the respective destination. Traffic between STAs within a BSS may be sent, for example, through the AP, where the source STA may send traffic to the AP, and the AP may deliver the traffic to the destination STA. Traffic between STAs within a BSS may be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic may be sent between (e.g., directly between) a source STA and a destination STA using a direct link setup (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and STAs within or using the IBSS (e.g., all of the STAs) may communicate directly with each other. The IBSS mode of communication may be referred to herein as an "ad hoc" communication mode.

[0063] When using the 802.11ac infrastructure mode of operation or a similar mode of operation, an AP may transmit 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 that is dynamically set via signaling. The primary channel may be the operating channel of the BSS, but may be used by STAs to establish a connection with the AP. In certain representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. With CSMA / CA, STAs (e.g., all STAs), including the AP, may sense the primary channel. If the primary channel is sensed / 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 in a given BSS at any given time.

[0064] High Throughput (HT) STAs may use 40 MHz wide channels for communication, which may be formed, for example, through a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels.

[0065] A Very High Throughput (VHT) STA may support 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels. A 40 MHz and / or 80 MHz channel may be formed by combining contiguous 20 MHz channels. A 160 MHz channel may be formed by combining eight contiguous 20 MHz channels or by combining two non-contiguous 80 MHz channels, which may be referred to as an 80+80 configuration. For the 80+80 configuration, after channel encoding, the data may pass through a segment parser that may split the data into two streams. Inverse Fast Fourier Transform (IFFT) processing and time-domain processing may be performed separately on each stream. The streams may be mapped to two 80 MHz channels, and the data may be transmitted by the transmitting STA. At the receiver of the receiving STA, the operations described above for the 80+80 configuration may be reversed, and the combined data may be transmitted to the Medium Access Control (MAC).

[0066] Sub-1 GHz operating modes are supported by 802.11af and 802.11ah. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah compared to those used in 802.11n and 802.11ac. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, while 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to representative embodiments, 802.11ah may support meter-type control / machine-type communications, such as MTC devices, within a macro coverage area. MTC devices may have limited capabilities, including, for example, support for (e.g., only support for) certain specific and / or limited bandwidths. MTC devices may include batteries with above-threshold battery life (e.g., to maintain very long battery life).

[0067] WLAN systems that can support multiple channels and channel bandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include a channel that can be designated as a primary channel. The primary channel can have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel can be configured and / or limited by a STA from among all STAs operating in the BSS that support the minimum bandwidth operating mode. In an 802.11ah embodiment, the primary channel can be 1 MHz wide for STAs (e.g., MTC-type devices) that support (e.g., only) the 1 MHz mode, even if the AP and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or Network Allocation Vector (NAV) configuration can depend on the status of the primary channel. For example, if the primary channel is busy due to a STA (that only supports 1 MHz operating mode) transmitting to the AP, the entire available frequency band may be considered busy, even though most of the frequency band may remain idle and be available for use.

[0068] In the United States, the available frequency band that can be used by 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.

[0069] 1D is a system diagram illustrating the RAN 113 and the CN 115, according to one embodiment. As mentioned 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 communicate with the CN 115.

[0070] The RAN 113 may include gNBs 180a, 180b, and 180c, although it will be understood that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, and 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, and 102c over the air interface 116. In an embodiment, the gNBs 180a, 180b, and 180c may implement MIMO technology. In an example, the gNBs 180a, 180b may transmit signals to and / or receive signals from the gNBs 180a, 180b, and 180c using beamforming. Thus, the gNB 180a may transmit and / or receive wireless signals to and / or from the WTRU 102a using, for example, multiple antennas. In one embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. In an example, the gNB 180a may transmit multiple component carriers to the 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 one embodiment, the gNBs 180a, 180b, 180c may implement Coordinated Multi-Point (CoMP) technology. In an example, the WTRU 102a may receive coordinated transmissions from the gNBs 180a and 180b (and / or 180c).

[0071] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with scalable numerology. In examples, the 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 transmission time intervals (TTIs) of different or scalable lengths (e.g., including different numbers of OFDM symbols and / or lasting different lengths of absolute time).

[0072] 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 without accessing another RAN (e.g., eNodeBs 160a, 160b, 160c, etc.). In a standalone configuration, the WTRUs 102a, 102b, 102c may utilize 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 unlicensed bands. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate with and connect to gNBs 180a, 180b, 180c while also communicating with and connecting to another RAN, such as eNodeBs 160a, 160b, 160c. In an example, the WTRUs 102a, 102b, 102c may implement DC principles 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 eNodeBs 160a, 160b, 160c may act as mobility anchors for the WTRUs 102a, 102b, 102c, and the gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0073] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, support for network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data to User Plane Functions (UPFs) 184a, 184b, routing of control plane information to Access and Mobility Management Functions (AMFs) 182a, 182b, etc. As shown in FIG. 1D, the gNBs 180a, 180b, 180c may communicate with each other via an Xn interface.

[0074] 1D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. While each of the foregoing elements is depicted as part of the CN 115, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0075] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and may function as a control node. In an example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, supporting network slicing (e.g., handling different PDU sessions with different requirements), selecting a particular SMF 183a, 183b, managing registration areas, terminating NAS signaling, mobility management, etc. Network slicing may be used by the AMF 182a, 182b to customize the CN support of the WTRUs 102a, 102b, 102c based on the type of service utilizing the WTRUs 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 massive mobile broadband (eMBB) access, 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.

[0076] The SMFs 183a, 183b may be connected to the AMFs 182a, 182b in the CN 115 via an N11 interface. The SMFs 183a, 183b may also be connected to the UPFs 184a, 184b in the CN 115 via an N4 interface. The SMFs 183a, 183b may select and control the UPFs 184a, 184b and configure the routing of traffic through the UPFs 184a, 184b. The SMFs 183a, 183b may perform other functions such as managing and assigning WTRU IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notification, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0077] The UPFs 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an 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 UPFs 184, 184b may perform other functions such as routing and forwarding packets, enforcing user plane policy, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, etc.

[0078] The CN 115 may facilitate communication with other networks. In an example, the CN 115 may include or 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. Additionally, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to local data networks (DNs) 185a, 185b through the UPFs 184a, 184b via an N3 interface to the UPFs 184a, 184b and an N6 interface between the UPFs 184a, 184b and the DNs 185a, 185b.

[0079] 1A-1D and their corresponding descriptions, one or more or all of the functions described herein with respect to one or more of the WTRUs 102a-d, base stations 114a-b, eNodeBs 160a-c, MME 162, SGW 164, PGW 166, gNBs 180a-c, AMFs 182a-b, UPFs 184a-b, SMFs 183a-b, DNs 185a-b, and / or any other devices described herein may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more or all of the functions described herein. In examples, the emulation devices may be used to test other devices and / or simulate network and / or WTRU functions.

[0080] The emulation device may be designed to implement one or more tests of other devices in a lab environment and / or an operator network environment. In an example, one or more emulation devices may perform one or more or all functions while fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to test other devices in the communication network. One or more emulation devices may perform one or more or all functions while temporarily implemented / deployed as part of a wired and / or wireless communication network. The emulation device may be directly coupled to another device for testing purposes and / or may perform the tests using terrestrial wireless communication.

[0081] One or more emulation devices may perform one or more functions, inclusive, while not being implemented / deployed as part of a wired and / or wireless communication network. In examples, the emulation devices may be utilized in test scenarios in a test lab and / or in an undeployed (e.g., test) wired and / or wireless communication network to implement testing of one or more components. One or more emulation devices may be test equipment. Direct RF coupling and / or wireless communication via RF circuitry (which may, for example, include one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0082] The configuration(s) referred to herein, such as the configuration received at the WTRU, may refer to configuration information.

[0083] This specification is provided for illustrative purposes and does not limit in any way the applicability of the methods described herein to other wireless technologies. The term network may refer to one or more gNBs that may be associated with one or more transmit / receive points (TRPs) or any other node in a radio access network (RAN).

[0084] The timing / angle positioning method may include a positioning method that uses a reference signal (e.g., SL-PRS, etc.). 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 transmitted (e.g., by the WTRU to between WTRUs). The receiver may perform measurements (e.g., RSTD, AoA, RSRP) for determining the location of the WTRU (e.g., the WTRU that transmitted the SL-PRS).

[0085] The RTT positioning method may include a positioning method that may include two WTRUs transmitting an SL-PRS between each other. In an example, the anchor WTRU may transmit the SL-PRS to the target WTRU. The target WTRU may receive the SL-PRS from the anchor WTRU. The target WTRU may transmit 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 transmitted from the anchor WTRU. The target WTRU may report the WTRU Tx-RX time difference to the anchor WTRU.

[0086] The positioning methods described herein may be used to determine the relative location and / or absolute position (eg, absolute position with respect to a geographic or local coordinate system) of a target WTRU with respect to an anchor WTRU.

[0087] The position may be provided. In an example, the absolute position of the WTRU may be with respect to a geographic coordinate system (GCS) or a local coordinate system (LCS). In an example, the relative position of the target WTRU may be with respect to one or more of a distance from the second WTRU (e.g., the anchor WTRU), an angle from the second WTRU (e.g., the anchor WTRU), or a reference point having a known location.

[0088] The SL-PRS configuration may include at least one or more of the following: SL-PRS resource ID, SL-PRS sequence ID (e.g., or other ID used to generate the 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, list of SL-PRS resources within the resource set, number of SL-PRS symbols, muting pattern 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, transmit angle), spatial direction information of SL-RS reception (e.g., beam ID used to receive SL RS, angle of arrival), frequency layer ID, WTRU ID, SL-PRS ID.

[0089] The network may include one or more of an AMF, a gNB, or an NG-RAN. "Pre-configured" and "configured" 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 (PRS(s))" or "PRS resource(s)" may be used interchangeably herein. The above-mentioned "PRS (PRS(s))" or "PRS resource(s)" may belong to different PRS resource sets. "PRS" or "DL-PRS" or "DL PRS" may be used interchangeably herein. "Measurement gap" or "measurement gap pattern" may be used interchangeably herein. "Measurement gap pattern" may include parameters (e.g., measurement gap duration, measurement gap repetition period, and measurement gap periodicity).

[0090] The PRU may include a WTRU or a TRP. The WTRU or TRP may include a location (e.g., altitude, latitude, longitude, geographic coordinates, or local coordinates) known by the network (e.g., gNB or LMF). The PRU may be the same as (e.g., have the same capabilities as) a WTRU or TRP (e.g., capable of receiving a PRS, transmitting an SRS or an SRS for positioning, returning measurements, or transmitting a PRS). A WTRU operating as a PRU may be used (e.g., by the network) for calibration purposes (e.g., precise unknown timing offset, precise unknown angular offset).

[0091] The LMF may be a node or entity (e.g., a network node of an entity) that may support positioning (e.g., that may be used for or to support positioning). The node or entity may be on behalf of the LMF.

[0092] Measurements may be obtained. The measurements may be associated with the location of the WTRU. In an example, the absolute location of a target WTRU (e.g., a WTRU to be positioned) may be determined using the absolute location of a second WTRU (e.g., a first anchor WTRU). Using the absolute location of the second WTRU may avoid Uu positioning and the associated overhead or GNSS / GPS (e.g., for precise positioning), which may consume power and time.

[0093] In an example, when the absolute position of the second WTRU is derived based on the absolute position of the second anchor WTRU, errors associated with the absolute positions of the first and second anchor WTRU absolute positions may propagate to the absolute position of the target WTRU.

[0094] 2 shows an example of error propagation. In this example, the absolute position of WTRU_B 202 may be determined (e.g., by WTRU_B 202) based on location information of WTRU_A 204 and the relative position of WTRU_B 202 with respect to WTRU_A 204. If the location information of WTRU_A 204 includes an error, indicated by "err1" in the figure, the resulting accumulated uncertainty for the location of WTRU_B 202 may be err1 + err2, where err2 is the uncertainty related to 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 in the location of WTRU_C206 becomes err1+err2+err3, where err2 is the uncertainty related to the relative position between WTRU_C206 and WTRU_B202 (e.g., when the absolute position of WTRU_C206 is determined by WTRU_C206 based on the absolute position of WTRU_B202).

[0095] 3 shows an example of error propagation. With respect to error propagation, Anchor_A 302, Anchor_B 304, and Anchor_C 306 may be used (e.g., by target WTRU 308 for SL TDOA positioning). GNSS / GPS 309 may be used (e.g., by Anchor_A 302) for determining the absolute position of Anchor_A 302. SL positioning may be used (e.g., by Anchor_B 304 with WTRU_D 310) for determining the absolute position of Anchor_B. GNSS / GPS may be used (e.g., by WTRU_E 312) for determining the position of WTRU_E 312. Errors associated with absolute positions (e.g., the absolute position of WTRU_F 314) may propagate to the absolute position of Anchor_B 304. The absolute position of Anchor_C306 may be determined (e.g., by Anchor_C306) based on SL positioning (e.g., SL positioning with WTRU_F314). The absolute position of WTRU_F314 may be determined (e.g., by WTRU_F314) based on Uu positioning. Errors associated with WTRU_F314 may propagate to the absolute position (e.g., of Anchor_C306). Different degrees of error may affect the anchor WTRU (e.g., WTRU). Accumulated error at the anchor WTRU may affect the accuracy of the absolute position of the target WTRU.

[0096] The location uncertainty information may be determined based on or may include one or more types of errors. Location uncertainty, location uncertainty information, uncertainty metric, and uncertainty may be used interchangeably herein. In an example, at least one of the following uncertainty metrics may be used (e.g., by the WTRU) to determine whether the anchor WTRU is likely using SL positioning: In an example, the metric may include an uncertainty regarding the absolute position of the anchor WTRU. In an example, the metric may include a tier of uncertainty associated with the absolute position of the anchor WTRU. The tier of uncertainty (e.g., a tier associated with the absolute uncertainty associated with the absolute position of the anchor WTRU) may be a quantized uncertainty regarding the absolute position of the anchor WTRU. The uncertainty metric may include a degree of uncertainty associated with the absolute position of the anchor WTRU, where the degree indicates how many times the original actual location was referenced (e.g., to determine the current absolute position). The uncertainty metric may include an estimated uncertainty of the absolute position of the target WTRU.

[0097] Regarding the type of error, the target WTRU may be configured with error criteria (e.g., the degree of uncertainty may be less than a preconfigured threshold, the uncertainty regarding the anchor WTRU's absolute position may be less than a preconfigured threshold) to determine whether the WTRU can be used for SL positioning.

[0098] Absolute position and relative position may be used interchangeably herein. In an example, a relative position may be defined as a position relative to a reference node (e.g., a distance and angle relative to the reference node).

[0099] In an example, if the target WTRU is within the 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 from the network associated with the anchor WTRU regarding an absolute position and an uncertainty metric). If the target WTRU is out of the coverage of the network, a positioning request may be sent (e.g., the target WTRU may send or broadcast a positioning request to nearby WTRUs). The target WTRU may wait for a response from the anchor WTRU, and the presence of nearby anchor WTRUs (e.g., anchor WTRUs with which the target WTRU will perform SL positioning) may be determined (e.g., by the target WTRU). Assistance information associated with the anchor WTRU may be received from the anchor WTRU (e.g., by the target WTRU) (e.g., the assistance information may include an absolute position and an uncertainty metric).

[0100] The WTRU may determine uncertainty information related to the location of the WTRU. The uncertainty related to the absolute position (e.g., of the target WTRU) may be defined as follows: The uncertainty related to the absolute position (e.g., of the target WTRU) may be expressed in terms of the absolute position (e.g., as a range). In an example, if the horizontal position uncertainty is ±2 m and the estimated location on the horizontal axis is 1.5 m from the origin, the possible locations (e.g., of the target WTRU) may be between −0.5 m and 3.5 m.

[0101] A list of anchor WTRUs may be received (e.g., received by the WTRU from the network). Information related to the anchor WTRUs, such as absolute location and its associated uncertainty, may be received (e.g., received by the target WTRU). If the uncertainty regarding the absolute location (e.g., of the anchor WTRU) is below a preconfigured threshold, a decision may be made (e.g., by the target WTRU) to use the anchor WTRU.

[0102] An instruction to find at least N anchor WTRUs on which to perform a positioning method (e.g., SL-TDOA) may be received (e.g., received by the target WTRU from the network). If the target WTRU is unable to find the N anchor WTRUs, a decision may be made (e.g., by the target WTRU) to perform a default positioning method that is not dependent on the anchor WTRU (e.g., DL-TDOA or GNSS / GPS-based positioning). If a default positioning method is not configured, a decision may be made (e.g., determined by the WTRU) to send a request for a positioning method to the anchor WTRU and / or the network (e.g., LMF, gNB).

[0103] Once N anchor WTRUs with location uncertainty below a threshold have been found (eg, by a target WTRU), a determination may be made (eg, by the target WTRU) using the following example.

[0104] In an example, it may be determined (e.g., determined by the target WTRU) that the uncertainty of the target WTRU's position is based on the uncertainty (e.g., the uncertainty of the anchor WTRU's location). If more than one anchor WTRU is used for positioning, the uncertainty associated with the target WTRU's location may be determined (e.g., by the target WTRU) using a function that derives an overall uncertainty based on the uncertainty (e.g., the uncertainty regarding the anchor WTRU's absolute location). Examples are described herein.

[0105] In an example, it may be determined (e.g., by the target WTRU) to accumulate uncertainty related to the location of the anchor WTRU. If the location of the target WTRU is based on PRS transmitted from at least three anchor WTRUs and the location uncertainty ranges of the at least three anchor WTRUs are determined to be ±3 m, ±2 m, and ±5 m, respectively, the location-related uncertainty may be determined (e.g., determined by the WTRU) to be 3 + 2 + 5 = 10 meters. Uncertainties based on measurement errors and uncertainties associated with the arrival times of the SL-PRS, RSTD, AoA, and / or AoD may be determined (e.g., by the WTRU).

[0106] In an example, an instruction to calculate the uncertainty based on the weight may be received (e.g., received by the target WTRU). 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 the sum of the RSRPs (e.g., to obtain the weight) and divide the RSRP by this sum. Based on the weight, the WTRU may determine the uncertainty by applying the weight to the uncertainty.

[0107] In an example, a target WTRU may indicate which error sources affect the uncertainty (e.g., of the WTRU's absolute position). The association between the error sources and the target WTRU's absolute position may be included in assistance information provided to another target WTRU once the target WTRU becomes an anchor WTRU. The error sources may include at least one or more of the following: errors associated with the anchor WTRU's absolute position, measurement errors (e.g., ToA, RSTD, RSRP, WTRU Tx-Rx time), LOS / NLOS indicators associated with measurements, transmit or receive timing errors (e.g., at the anchor WTRU or target WTRU), synchronization errors (e.g., clock synchronization errors between anchor WTRUs).

[0108] Features described herein may include a WTRU behavior (eg, associated WTRU behavior) for determining the uncertainty of the WTRU location based on the degree of uncertainty.

[0109] The degree of uncertainty may include: 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., how many times) uncertainty is associated with a previously determined absolute position; In an example, the degree of uncertainty may indicate how often (e.g., how many times) uncertainty is added to a determined (e.g., previously determined) absolute position.

[0110] Examples of determining the degree of uncertainty may include the following: When it is decided (e.g., determined by the first target WTRU) to use the absolute location of the first anchor WTRU, a degree of uncertainty may be inherited (e.g., by the first target WTRU from the first anchor WTRU), and the degree of uncertainty may be incremented by one count (e.g., the degree of uncertainty associated with the first target WTRU). When the first target WTRU becomes the second anchor WTRU and the second target WTRU decides to use the absolute location of the second anchor WTRU, the second target WTRU may inherit the degree of uncertainty of the second anchor WTRU and increment the degree by one count. If the first anchor WTRU determines its location using a positioning method that does not require an anchor WTRU, the first anchor may reset the degree of uncertainty to 0.

[0111] A WTRU with a degree of uncertainty of 0 may include a WTRU that determines its absolute position based on a method that is independent of the absolute position of the anchor WTRU (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).

[0112] In the example shown in FIG. 2, the degree of uncertainty at WTRU_C 206 is two because the absolute position of WTRU_A 204 is inherited twice (e.g., once to WTRU_B 202, and once to WTRU_C 206).

[0113] If the absolute location (e.g., the absolute location of the target WTRU) is determined to be based on two or more anchor WTRUs (e.g., determined by the target WTRU) and the anchor WTRUs have different degrees of uncertainty, it may be decided (e.g., determined by the target WTRU) to perform at least one of the following for succession:

[0114] In an example (e.g., the example shown in FIG. 3), it may be decided to inherit the highest degree of uncertainty (e.g., the highest degree of uncertainty among the anchor WTRUs) and increment the degree by 1. In an example, if the degrees of uncertainty of anchor_A 302, anchor_B 304, and anchor_C 306 are 3, 5, and 3, respectively, the target WTRU 308 may decide to set its degree of uncertainty to 6.

[0115] In an example, it may be decided to calculate the average degree of uncertainty among the anchor WTRUs and increment the degree by 1. In an example, if the degrees of uncertainty 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.

[0116] In an example, a decision may be made (e.g., by the 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 decision 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 instruction / configuration may be received (e.g., received by the target WTRU) from the network or anchor WTRU with a threshold of 1. Thus, a decision 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, a PRU, a gNB, and / or a TRP. Alternatively, the WTRU may be configured to select only an RSU, a PRU, a gNB, and / or a TRP as anchor WTRUs for determining the WTRU's absolute position via SL positioning and / or Uu positioning.

[0117] In an example, two or more uncertainty metrics (e.g., degree of uncertainty, uncertainty associated with absolute position) may be used (e.g., by the target WTRU). In an example, a decision may be made (e.g., by the target WTRU) to use both the degree of uncertainty (e.g., of the anchor WTRU) and the uncertainty regarding the absolute position to determine whether to use the anchor WTRU (e.g., for positioning). In an example, a decision may be made (e.g., by the target WTRU) to use the anchor WTRU for positioning if one or more of the following are met: the degree of uncertainty associated with the anchor WTRU is below a first threshold, and / or the uncertainty associated with the anchor WTRU's absolute position is below a second threshold.

[0118] An anchor WTRU may be selected (e.g., by a target WTRU) for SL positioning based on a tier or level of uncertainty associated with the error associated with the anchor WTRU's absolute uncertainty. The error tier may indicate a level of error that indicates how large the error is, and the error tier may also be a quantized uncertainty of the absolute position.

[0119] In an example, error tier 1 may indicate that the error is low, while error tier 3 may indicate that a large error may exist. The tiers may include ranges of error. In an example, error tier 1 may include an error below 1 meter. Tier 2 may include, for example, an error of 1 meter or greater and less than 3 meters. The absolute location (e.g., of the anchor WTRU) may be associated with the error tier. A decision may be made (e.g., determined by the target WTRU) to select an anchor WTRU having an error tier below a preconfigured threshold.

[0120] When the absolute position is determined (e.g., determined by the target WTRU), an error associated with the position may be determined (e.g., determined by the target WTRU) based on the associated uncertainty. The error tier 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 position of the target WTRU may be used to determine the error tier. In an example, a mapping table may be received (e.g., received by the WTRU from the network and / or anchor WTRU), with rows having ranges of uncertainty for the absolute position. The positioning method may be used to determine the error tier. In an example, it may be determined (e.g., determined by the WTRU) that the error tier is to be increased by a particular amount (e.g., for the positioning method). In an example, if a TDOA positioning method is used, the tier level may be incremented by 1. The uncertainty of the measurement (e.g., time of arrival, RSRP, multipath measurements) may be used to determine the error tier. The number of anchor WTRUs may be used to determine the error tier. In an example, if the number of anchor WTRUs used for positioning is greater than a preconfigured threshold, it may be decided (eg, determined by the WTRU) to increase the tier level by one.

[0121] In an example, when two or more anchor WTRUs are used for positioning, the WTRU determines its own tier level as follows: Using the uncertainty associated with the anchor WTRU's absolute position, the target WTRU first determines the uncertainty associated with the target WTRU's absolute position. Using a mapping table, the target WTRU determines its tier, which indicates the uncertainty range and corresponding error tier. In an example, error tier 1 is defined as an uncertainty below 1 meter. Tier 2 is defined as an uncertainty greater than or equal to 1 meter and less than 3 meters, for example. Tier 3 is defined as an uncertainty greater than 3 meters but less than or equal to 5 meters.

[0122] In an example, it may be determined (e.g., by the WTRU) to select a set of anchor WTRUs for SL positioning based on an estimation error associated with the absolute position of the target WTRU. The target WTRU may determine the estimation error based on assistance information that the target WTRU may have received from the anchor WTRU and / or the network (e.g., LMF, gNB).

[0123] The set of anchor WTRUs may be selected (e.g., by the target WTRU) based on one or more of the following conditions: a preconfigured list (e.g., provided by the anchor WTRU or the network), a channel condition (e.g., the SSB / SL reference signal RSRP associated with the anchor WTRU exceeds a preconfigured threshold), or an LOS / NLOS condition (e.g., the LOS indicator between the target WTRU and the anchor WTRU exceeds a preconfigured threshold).

[0124] The anchor WTRU may be selected (eg, by the target WTRU) for up to N WTRUs, where N may be the number of WTRUs required for the configured positioning method.

[0125] Based on the selected anchor WTRU, an estimation error may be determined (e.g., by the target WTRU) based on one or more of the following: The estimation error may be determined based on an uncertainty associated with an absolute position (e.g., of the anchor WTRU). In an example, the WTRU may determine to accumulate uncertainty associated with the anchor WTRU's absolute position. The estimation error may be determined based on a range of measurements (e.g., range of time of arrival, RSTD, RSRP) associated with the anchor WTRU. In an example, if the positioning method uses RSTD, the estimation error may be determined (e.g., determined by the WTRU) based on a mapping function that may map the range of RSTD to the uncertainty of the target WTRU's absolute position. The estimation error may be determined based on expected values ​​of the measurements (e.g., expected time of arrival, expected RSTD, expected RSRP). The estimation error may be determined based on the positioning method. In an example, the WTRU may be configured with a TDOA-based SL positioning method having a set of anchor WTRUs. The uncertainty associated with the target's absolute position may be determined (e.g., determined by the WTRU) based on the results of the positioning method.

[0126] In an example, an indication (e.g., by the target WTRU) may be received (e.g., from the network (e.g., LMF, gNB)) indicating which uncertainties to use for determining the estimation error. In an example, the WTRU may determine the estimation error based on a combination of the aforementioned uncertainties. In an example, the WTRU determines the estimation error as the sum of the uncertainty of the target WTRU's absolute position 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 summation, multiplication, or weighted summation.

[0127] In an example, if the estimation error is below a preconfigured threshold, it may be decided (e.g., by the target WTRU) to use the set of anchor WTRUs associated with the estimation error (e.g., estimation error for SL positioning). If the estimation error is equal to or greater than a preconfigured threshold, it may be decided (e.g., by the target WTRU) to select another set of anchor WTRUs to determine the estimation error. If no further anchor WTRU can be selected (e.g., by the target WTRU), it may be decided (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 default positioning, a request for configuration of a positioning method may be sent (e.g., by the WTRU) to the anchor WTRU or the network.

[0128] In the examples described herein, "estimated uncertainty" may be used interchangeably with "estimated degree of uncertainty" or "estimated error tier."

[0129] A combination of selection criteria may be associated with the selection of a WTRU (eg, an anchor WTRU).

[0130] In an example, a configuration related to a priority level of uncertainty may be received (e.g., by the WTRU) and used to determine an anchor WTRU to use for SL positioning. In an example, an instruction may be received (e.g., from the network and to the WTRU) to use a degree of uncertainty with a higher priority than uncertainty associated with absolute positioning of the anchor WTRU.

[0131] In an example, an order of uncertainty for selection of an anchor WTRU may be received (e.g., by the target WTRU). In an example, a first set of anchor WTRUs may be selected (e.g., by the 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 the target WTRU) based on uncertainties associated with their absolute positions.

[0132] In an example, a decision may be made (e.g., by the WTRU) to select a set of anchor WTRUs based on criteria for uncertainty and measurements. In an example, uncertainty information relating to a first set of anchor WTRUs and their absolute positions may be received (e.g., by the WTRU from the network). A configuration may be received (e.g., by the WTRU) from the network to determine the anchor WTRU based on the degree of uncertainty. Two thresholds may be received (e.g., by the WTRU), a first threshold for the RSRP of the SL reference signals and a second threshold for the degree of uncertainty. The RSRP of the SL reference signal resources from the anchor WTRU may be measured (e.g., by the WTRU). If the RSRP of the SL reference signals for at least one resource from the anchor WTRU exceeds the first threshold, a decision may be made (e.g., by the target WTRU) to use the anchor WTRU for SL positioning if the degree of uncertainty corresponding to the anchor WTRU exceeds the threshold. If the RSRP is below the first threshold, a decision may be made (e.g., by the target WTRU) to select the anchor WTRU if the associated degree of uncertainty is below the second threshold.

[0133] Up to N anchor WTRUs may be associated with the target WTRU.

[0134] In an example, the target WTRU can be composed of N, which is the maximum number of anchor WTRUs to be selected for SL positioning. M anchor WTRUs can be selected (e.g., by the target WTRU), and the availability of the anchor WTRUs based on M < N can meet the uncertainty criterion. In the example, since the degree of uncertainty associated with the absolute positions of the M anchor WTRUs is below a preconfigured threshold, it can be determined (e.g., by the target WTRU) to select the M anchor WTRUs. Based on the number of available anchor WTRUs, which positioning method to use can be determined (e.g., by the target WTRU). In the example, the target WTRU can be preconfigured using a table that associates the number of available anchor WTRUs with the positioning methods that the target WTRU can use. In the example, the table can indicate that SL-TDOA can be used by the target WTRU when N anchor WTRUs are available. When the number of available anchor WTRUs is less than N, the table can indicate that the target WTRU can use an RTT-based positioning method.

[0135] (For example, where the target WTRU selects anchor WTRUs based on the degree of uncertainty) An example of a flowchart is shown in FIG. 4. In this example, at 402, a list of anchor WTRUs can be received (e.g., by the target WTRU, from the network). At 404, the degree of error associated with the absolute location of the anchor WTRU can be obtained (e.g., by the target WTRU). At 406, if the degree of error is less than the threshold, the target WTRU can add the anchor WTRU to the pool at 408. At 410, the next anchor WTRU in the list can be selected (e.g., by the target WTRU). At �12, if the counter for the anchor WTRU is less than the limit, the search can continue at 414 (e.g., by the target WTRU).

[0136] The fallback behavior can be associated with using a default criterion (e.g., a criterion).

[0137] In an example, a configuration of a fallback uncertainty criterion may be received (e.g., by the WTRU). In an example, if an instruction is received (e.g., by the WTRU) from the network to use a degree of uncertainty with a higher priority than uncertainty associated with absolute positioning of the anchor WTRU, but the degree of uncertainty associated with the absolute position of the anchor WTRU is not available, it may be decided (e.g., by the WTRU) to use a default criterion (e.g., uncertainty regarding the absolute position) to determine which anchor WTRU to use for SL positioning.

[0138] When requested (e.g., by the network), a report (e.g., from the WTRU) may be sent (e.g., to the network) that includes one or more of the absolute location, an uncertainty metric (e.g., uncertainty, degree of uncertainty) associated with the absolute location, information related to the anchor WTRU, e.g., WTRU ID, and measurements used to determine the absolute location (e.g., RSRP, RSTD, ToA), where the measurements may be associated with a PRS resource ID, a PRS resource set ID.

[0139] The features described herein may have validity related to uncertainty.

[0140] 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 area validity (it may be determined (e.g., by the WTRU) that the uncertainty metric for the target WTRU and / or anchor WTRU may be valid within an area (e.g., a cell ID)) and time validity (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).

[0141] In an example, when the uncertainty metric associated with the absolute position is not valid, it may be decided (e.g., by the WTRU) to update the uncertainty metric according to 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 may be performed (e.g., by the WTRU) and the uncertainty metric associated with the positioning method may be obtained; if a default positioning method is not configured, a request to initiate positioning may be sent (e.g., by the WTRU to the network).

[0142] A quality determination (eg, WTRU-based or WTRU-based) of the anchor WTRU may be made (eg, by the target WTRU).

[0143] In an example, a request for positioning may be sent (e.g., by the WTRU to the network and / or anchor WTRU). The network and / or anchor WTRU may not know the accuracy requirements of the target WTRU, as the request may originate from the target WTRU. A list of anchor WTRUs 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 position, uncertainty metric associated with the absolute position) may be sent (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 prior knowledge (e.g., of the network of the target WTRU's location or approximate location).

[0144] The selection of the anchor WTRU may be prioritized.

[0145] The target WTRU may determine the anchor WTRU based on the category to which the anchor WTRU belongs (characteristics related to the anchor WTRU's location information may be classified) and / or the priority level associated with that category.

[0146] 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 how 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 capabilities) with a priority level associated with characteristics related to the anchor WTRU's location information. In an example, the WTRU may select the anchor WTRU based on the priority level. The WTRU may be pre-configured by the network (e.g., gNB, LMF) or a peer WTRU (e.g., a WTRU with LMF capabilities) with a list of categories, where the categories may consist of characteristics of the anchor WTRU's location information. A priority level may be associated with the category. The target WTRU may determine the priority level of the category based on configuration from the network / peer WTRU (e.g., via LPP, RRC, MAC-CE, DCI).

[0147] In examples, the anchor WTRU may belong to one or more of the following example categories:

[0148] Category 1: The anchor WTRU is in coverage, its location is determined via GNSS, and its location is verified by the network. Category 2: The anchor WTRU is out of coverage, its location is determined via GNSS, and its location is verified by the network. Roadside units or positioning reference units may belong to this category. Category 3: The anchor WTRU is in coverage, its location is determined via a RAT-dependent positioning method (e.g., DL-TDOA, RTT, DL-AoD, UL-AoA, UL-TDOA), and its location is verified by the network. Category 4: The anchor WTRU is in coverage, its location is determined via GNSS, and its location is not verified by the network. Category 5: The anchor WTRU is in coverage, its location is determined via a RAT-dependent positioning method (e.g., DL-TDOA, RTT, DL-AoD, UL-AoA, UL-TDOA), and its location is not verified by the network. Category 6: The anchor WTRU is out of coverage, its location is determined via GNSS, and its location 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.

[0149] 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 the target WTRU discovers more than one anchor WTRU through the discovery process, the target WTRU may determine the categories of the anchor WTRUs and determine a subset of WTRUs based on the priorities associated with the categories. In an example, if the target WTRU is out of coverage, the WTRU may determine, based on the determined positioning method (e.g., via a hard-coded configuration in the specification, a default / current configuration), that there are four anchor WTRUs (e.g., required) for the positioning method. The target WTRU may discover seven anchor WTRUs, with two WTRUs belonging to Category 1, one WTRU belonging to Category 3, one WTRU belonging to Category 4, two WTRUs belonging to Category 6, and one WTRU belonging to Category 7. If the priority levels are associated in descending order with respect to category number (e.g., category 1 has the highest priority and category 7 has the lowest priority), the WTRU may decide to select two WTRUs in category 1, one WTRU in category 3, and one WTRU in category 4.

[0150] If the target WTRU selects (e.g., needs to select) an anchor WTRU from the same category, the WTRU may determine the anchor WTRU based on the anchor WTRU ID (e.g., may choose the anchor WTRU from the smallest WTRU ID). The WTRU may select the anchor WTRU based on instructions from the network.

[0151] A WTRU may discover potential anchor WTRUs according to one or more of the following.

[0152] The list of anchor WTRUs may be provided by the network or a peer WTRU (e.g., a WTRU with LMF capability) via unicast / groupcast / broadcast. In an example, the target WTRU may provide its location (e.g., cell / area ID, location estimated by GNSS or a RAT-dependent positioning method) to the network, and the WTRU may receive a list of anchor WTRUs that are within a threshold from the reported location of the target WTRU.

[0153] The discovery process may be performed by the target WTRU. In an example, the target WTRU may perform a discovery procedure and identify the anchor WTRU with location information (e.g., coordinates of the anchor WTRU, cell / area ID of the cell / area to which the anchor WTRU belongs).

[0154] The WTRU may determine at least one of the following from a discovered / configured anchor WTRU (eg, via higher layer messages such as RRC, SCI, SL MAC-CE, NAS messages, SLPP messages, etc.):

[0155] The WTRU may determine the WTRU ID of the anchor WTRU. The WTRU may determine the anchor WTRU's location information (e.g., the WTRU's coordinates according to the GCS / LCS, the cell / area ID / index where the anchor WTRU is located). The WTRU may determine the uncertainty of the anchor WTRU's location information. The WTRU may determine the positioning method used to determine the anchor WTRU's location information. The WTRU may determine whether the anchor WTRU's location information is verified by the network. In an example, the anchor WTRU may need to report its location and / or measurements to the network to verify its location. An indicator may be used to indicate whether the anchor WTRU's location is verified (e.g., indicator=1) or not (e.g., indicator=0).

[0156] The WTRU may determine whether the anchor WTRU's location information is determined based on a verified location or a partially verified location, where partial verification may be expressed numerically (e.g., 50% verified, 100% verified, and the percentage may be determined based on the positioning method and / or how many WTRUs with verified locations were used in the positioning). In an example, using the scenario shown in FIG. 3, if the location of WTRU_E 312 (determined by GNSS 309) is verified by the network and the location of WTRU_D 310 (determined by relative positioning) is not verified by the network, the target WTRU 308 may determine that the location of Anchor_B 304 is partially verified. In an example, using the scenario shown in FIG. 3, 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 a verified location. If the target WTRU 308 determines, according to instructions / configuration from the network, that Anchor_B 304 does not need to perform verification with 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, 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 (e.g., indicator=0).

[0157] The WTRU may determine the coverage status (eg, in coverage, out of coverage) of the anchor WTRU. The WTRU may determine the degree / tier of uncertainty of the anchor WTRU's location information.

[0158] Whether the location 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 on DL PRSs (e.g., RSTD, ToA, AoA, AoD) and reports the measurements to the network, the network may determine the location of the anchor WTRU, and the determined location may be verified by the network. If the anchor WTRU performs a WTRU-based positioning method, the anchor WTRU may need to send the determined location and corresponding measurements (e.g., measurements made on received PRSs) to the network for verification. The 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) was performed to determine the WTRU location.

[0159] In an example, the priority levels associated with the categories may depend on the coverage status of the target WTRU. If the target WTRU is in coverage, Category 3 may have a higher priority than Category 2, as described herein.

[0160] In the categories described herein, the WTRU location information may not be verified by the network, and information regarding whether verification regarding the WTRU location has been performed may be omitted from the categories.

[0161] 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 an accuracy (e.g., a range of error in the location estimate expressed in terms of distance units such as meters, a standard deviation of the location estimate, a variance of the location estimate). The categories may include accuracy information in addition to the information elements described in the categories described herein.

[0162] The categories described herein may include mobility of the anchor WTRU (eg, the anchor may be mobile or fixed).

[0163] The categories can consist of one or more of the following information:

[0164] The category may include the uncertainty of the anchor WTRU's location information. The category may include the positioning method (eg, WTRU-assisted / WTRU-based) used to determine the location information.

[0165] The categories may include whether the anchor WTRU's location information is verified by a 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 anchor WTRU's location is verified (e.g., indicator=1) or not (e.g., indicator=0).

[0166] The categories may include whether the anchor WTRU's location information was determined based on a verified location or a partially verified location. Partial verification may be expressed numerically (e.g., 50% verified, 100% verified, and the percentage may be determined based on the positioning method and how many WTRUs with verified locations were used during positioning). In an example, using the example shown in FIG. 3, if the location of WTRU_E (determined by GNSS) is verified by the network and the location of WTRU_D (determined by relative positioning) is not verified by the network, the target WTRU may determine that the location of Anchor_B is partially verified. In an example, using the scenario shown in FIG. 2, 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 a verified location. If the target WTRU determines, according to instructions / configuration from the network, that Anchor_B will not perform verification with the network, the location of Anchor_B may be verified. If the location of the anchor WTRU is determined based on a mix of anchor WTRUs whose locations are verified and anchor WTRUs whose locations are 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 (e.g., indicator=0).

[0167] The category may include the coverage status of the anchor WTRU (e.g., in coverage, out of coverage). The category may include the degree / tier of uncertainty. The category may include the mobility status (mobile or fixed). The category may include the type of WTRU (e.g., PRU / RSU / WTRU with LMF capability).

[0168] Examples may include the following: The WTRU may be pre-configured with a list of categories for the anchor WTRU, and categories from the list of categories may be associated with priority levels. The WTRU may be configured with positioning methods (e.g., SL-TDOA) from the network. Through a discovery procedure, the WTRU may determine the anchor WTRU. The WTRU may determine the number of anchor WTRUs needed for the positioning method. The anchor WTRU may be selected in descending order of priority level according to 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 perform measurements on the SL-PRS transmitted by the anchor WTRU, and the WTRU may report the selected anchor WTRU and the measurements to the network.

[0169] A decision may be made (eg, by the target WTRU) to reset or refine the uncertainty associated with the absolute position (eg, of the target WTRU) based on conditions.

[0170] The uncertainty can be reduced through a default positioning method.

[0171] In an example, a decision may be made (e.g., by the target WTRU) to reduce the uncertainty associated with the position (e.g., of the WTRU) if one or more of the following are met: the uncertainty associated with the absolute position (e.g., of the target WTRU) may be higher than a preconfigured threshold, and / or an instruction to improve the uncertainty is received (e.g., by the target WTRU from the network).

[0172] If one or more of the above are met, a decision 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 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 sent (e.g., by the WTRU to the network) to remove the WTRU from the list of anchor WTRUs.

[0173] A decision may be made (e.g., by the target WTRU) to reduce the degree of uncertainty regarding its location (e.g., of the target WTRU) if one or more of the following are met: In an example, the degree of uncertainty or error tier associated with the absolute location of the target WTRU may be higher than a preconfigured threshold; In an example, an instruction may be received (e.g., by the target WTRU from the network) to lower the degree of uncertainty (e.g., or error tier).

[0174] If one or more of the above are met, it may be decided (e.g., by the WTRU) to perform a default positioning method (e.g., GNSS / GPS) or an anchor WTRU-independent (e.g., any) positioning method. After performing the positioning method, the degree of uncertainty may be set to 0 or the error tier may be reset (e.g., by the WTRU) to a value associated with the positioning method.

[0175] The reduction of uncertainty may be on demand.

[0176] In an example, if the target WTRU is in coverage, and one or more of the above are met, it may be decided (e.g., by the WTRU) to send a request (e.g., to the network and / or anchor WTRU) to configure a set of anchor WTRUs or the anchor WTRU (e.g., for SL positioning). A set ID and / or WTRU ID may be indicated in the request (e.g., by the WTRU).

[0177] A 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 WTRUs to request, it may be decided (e.g., by the target WTRU) to perform a default positioning method (e.g., GNSS / GPS positioning).

[0178] In an example, if there is no set of WTRUs or WTRUs (e.g., no more) to request, a request may be sent (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, more slots to accommodate SL-PRS). When a new set of configurations is received (e.g., by the target WTRU from the anchor WTRU and / or network), a decision may be made (e.g., by the target WTRU) to perform a positioning method (e.g., with the initial anchor WTRU set).

[0179] In an example, if the target WTRU is out of coverage, the WTRU may send 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 decide to perform a default positioning method (e.g., GNSS / GPS positioning). In an example, the target WTRU may start a timer and search for a different anchor WTRU until the timer expires. The WTRU may receive an expiration time for the timer.

[0180] The positioning method used may be reported. In an example, if requested by the network or a peer WTRU (e.g., a WTRU with LMF capability), the target WTRU may report to the network (e.g., LMF, gNB) or peer WTRU (e.g., a WTRU with LMF capability) the positioning method used to determine its location (e.g., the target WTRU's location). If the target WTRU determines to use GNSS to determine its location, the target WTRU may indicate to the network that GNSS was used to determine the target WTRU's location.

[0181] An uncertainty associated with a WTRU location may be determined. In an example, a WTRU (e.g., a target WTRU) may determine an uncertainty associated with a WTRU location (e.g., uncertainty associated with the anchor WTRU's location information) based on a function of configuration and / or assistance data associated with the anchor WTRU. The WTRU may determine its location uncertainty as a function of the uncertainty of the anchor WTRU's location information, 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 such as TDOA is used, the uncertainty metric for the determined WTRU location may be an average of the uncertainty metrics for the anchor WTRUs. If a positioning method such as RTT is used, the uncertainty metric for the determined WTRU location may be the output of a non-linear function of the uncertainty metrics for the anchor WTRUs.

[0182] A parameter related to the uncertainty metric may be used to determine whether a quantity is below or above a threshold. As described herein, uncertainty below a threshold may refer to at least one of the following: the error tier is below a configured threshold, the degree of uncertainty is below a set threshold, and / or the maximum and / or minimum value of the uncertainty metric is below a set threshold. Examples of uncertainty below a configured threshold may be as follows: if the uncertainty metric is defined by a range (e.g., + / - 5m), the maximum value (e.g., 5m), the minimum value (e.g., -5m), or the absolute value of the maximum value of the range (e.g., 5m) is below a configured threshold.

[0183] The positioning method may be determined based on the uncertainty. In an example, the WTRU may determine an anchor WTRU to use for the positioning method via a discovery process. The WTRU may receive assistance information (e.g., an uncertainty metric) from the anchor WTRU. Based on the uncertainty metric of the anchor WTRU, the WTRU may determine an uncertainty metric for the configured positioning method (e.g., a RAT-dependent positioning method such as TDOA, RTT, AoA, AoD positioning method, or a RAT-independent positioning method such as GNSS, sensor-based, wifi-based positioning). Based on the determined uncertainty metric for the positioning method, the WTRU may decide to use the positioning method with the smallest uncertainty metric. In an example, the WTRU may determine the uncertainty metric for the positioning method as a function of the uncertainty of the anchor WTRU's location information, the assistance data, and / or the number of anchor WTRUs.

[0184] In an example, if a WTRU is configured with a TDOA positioning method and GNSS, the WTRU may determine an uncertainty metric associated with the TDOA positioning method based on the uncertainty metric of the anchor WTRU's location. The WTRU may determine an uncertainty metric associated with the GNSS positioning method. The WTRU may select the TDOA positioning method if the uncertainty metric associated with the TDOA method is less than the uncertainty metric associated with the GNSS positioning method.

[0185] After the WTRU determines the positioning method, the WTRU may determine an uncertainty metric associated with the determined WTRU location information.

[0186] In an example, the number of discovered anchor WTRUs for a positioning method may be greater than the number of anchor WTRUs (e.g., required number) for the positioning method. The number of anchor WTRUs (e.g., required number) for the positioning method may be configured by the network or a peer WTRU (e.g., a WTRU with LMF capability). In an example, if the number of discovered anchor WTRUs is greater than the number of anchor WTRUs (e.g., required number) for the positioning method (e.g., N), the WTRU (e.g., target WTRU) may select the anchor WTRU based on the following metrics, such as a priority level associated with the anchor WTRU (e.g., high, low, medium, a number between 0 and 1), distance of the anchor WTRU to the WTRU, RSRP of the signal (e.g., SL-PRS) transmitted from the anchor WTRU (e.g., select the N anchor WTRUs with the highest N RSRP values), coverage status (e.g., prioritize selection of an anchor WTRU that is in coverage over an anchor WTRU that is out of coverage), location of other WTRUs based on measurements by the network or peer WTRU (e.g., The WTRU may determine to select the N anchor WTRUs based on at least one of: an anchor WTRU having a verified location whose location is verified by a network or peer WTRU (e.g., a server WTRU, where the WTRU acts as an LMF by configuring SL-PRS to other WTRUs to determine location information from the other WTRUs, and the server WTRU may configure the SL-PRS to the WTRU based on a pre-configured SL-PRS, etc.); an anchor WTRU verified or indicated by the network or a peer WTRU (e.g., the server WTRU); and / or mobility status (e.g., prioritizing the selection of a fixed or low mobility anchor WTRU over a high mobility anchor WTRU). In an example, the WTRU (e.g., target WTRU) may send identification information (e.g., RNTI, WTRU ID) of the discovered anchor WTRU to the network or peer WTRU (e.g., server WTRU) and ask the network or peer WTRU for indication of the N anchor WTRUs.

[0187] The WTRU may include determining 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.

[0188] In an example, a configuration (e.g., a default positioning method, an SL positioning method, a threshold, or N (e.g., the number of anchor WTRUs required) may be received (e.g., by the WTRU from the network). The configuration information of the configuration may indicate the default positioning method, an error threshold, and / or a threshold number of anchor WTRUs. The target WTRU may be enabled to determine candidate anchor WTRUs and their respective uncertainty metrics from the candidate anchor WTRUs. The target WTRU may determine the anchor WTRU based on a response to the positioning request. The target WTRU may receive a PRS configuration and error information (e.g., location uncertainty) from the anchor WTRU. The PRC location uncertainty information may be used by the target WTRU to determine the target WTRU absolute position and the target WTRU uncertainty metric.

[0189] If the selected anchor WTRU exceeds a threshold number of anchor WTRUs, the target WTRU may determine the target WTRU absolute location using a sidelink positioning method. Under these conditions, the target WTRU uncertainty metric may be related to the uncertainty associated with the selected anchor WTRU and the uncertainty associated with the sidelink positioning method.

[0190] When the selected anchor WTRU is equal to or greater than the threshold number of anchor WTRUs, the processor may determine the target WTRU absolute position using a combination of the sidelink positioning method and the default positioning method.

[0191] The WTRU may select an anchor WTRU if the associated location uncertainty is below a preconfigured error threshold. If N anchor WTRUs are not found (e.g., by the WTRU), it may be decided (e.g., by the WTRU) to use a default positioning method (e.g., GNSS) to determine the absolute position (e.g., of the WTRU).

[0192] If at least N anchor WTRUs are found (e.g., by the WTRU), a pre-configured positioning method may be executed and an absolute position may be determined. An accumulated uncertainty may be determined (e.g., by the WTRU) based on one or more of the following: If the position is determined (e.g., by the WTRU) without using the anchor WTRU (e.g., GNSS), the accumulated error may be reset to the corresponding positioning error (e.g., GNSS), and the target WTRU may reset the target WTRU uncertainty metric to the uncertainty associated with the default positioning method, provided that the target WTRU absolute position is determined using the default positioning method.

[0193] If the position is determined using (e.g., by) an anchor WTRU, the error may be accumulated. The WTRU may accumulate an uncertainty metric based on the uncertainty metric associated with the selected anchor WTRU, provided that the target WTRU absolute position is determined using a sidelink positioning method.

[0194] When the WTRU is in-coverage, a report may be sent (e.g., by the WTRU to the network) including the absolute location, the associated uncertainty metric, and information related to the anchor WTRU used for SL positioning (e.g., WTRU ID) (e.g., when the WTRU enters coverage or when the WTRU is in-coverage). The target WTRU may be configured to send an indication of the target WTRU absolute location and the target WTRU uncertainty metric to the network node. The target WTRU may send information related to the selected anchor WTRU used for positioning to the network node when the target WTRU enters network coverage. The transmitted information may include the identity of the selected anchor WTRU.

[0195] Different uncertainty metrics may be associated with the anchor WTRU's decision.

[0196] In an example, a PRS configuration related to an anchor WTRU may be received (e.g., by the WTRU) (e.g., from a network (e.g., LMF, gNB)) along with associated error information (e.g., location uncertainty, degree of uncertainty), first and second error thresholds, N (number of anchor WTRUs required), and a positioning method. A first set 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 set of anchor WTRUs, a second set may be determined (e.g., by the WTRU), which may include WTRUs with degrees of uncertainty (e.g., lower than the first threshold). If the number of WTRUs in the second set is less than N, it may be determined (e.g., by the WTRU) to perform a default positioning method (e.g., GNSS, Uu-based positioning). Based on the second set of anchor WTRUs, a third set may be determined (e.g., by the WTRU), which may include WTRUs with uncertainties lower than the second threshold. If the number of WTRUs in the third set is less than N, it may be decided (e.g., by the WTRU) to perform a default positioning method (e.g., GNSS, Uu-based positioning). The SL positioning method may be performed and the 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 in coverage, a report may be sent (e.g., by the WTRU) including the absolute position and associated uncertainty metric, as well as a set of anchor WTRUs (e.g., WTRU IDs) used to determine the WTRU's position.

[0197] The measurements and uncertainty metrics may be associated with the anchor WTRU's decision.

[0198] In an example, a request for location information may be received (e.g., by the WTRU from a network). A PRS configuration related to an anchor WTRU may be received (e.g., by the WTRU) (e.g., from a network (e.g., LMF, gNB)) along with associated error information (e.g., degree of uncertainty), first and second error thresholds, N (the number of anchor WTRUs required), and a positioning method. A first set of anchor WTRUs may be received (e.g., by the WTRU from the network). Measurements (e.g., RSRPs) related to SL PRSs transmitted (e.g., from the set of anchor WTRUs) may be made (e.g., by the WTRU). If the measured RSRP for an anchor WTRU's SL-PRS is greater than or equal to a first threshold, a decision may be made (e.g., by the WTRU) to use the anchor WTRU for SL positioning. If the measured RSRP for the anchor WTRU's SL-PRS is below the first threshold and an uncertainty metric associated with the anchor WTRU's absolute position is below a second threshold, a decision may be made (e.g., by the WTRU) to use the anchor WTRU for SL positioning. The location 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 degree of uncertainty associated with the absolute location may be determined (e.g., by the WTRU) based on the greatest degree of uncertainty (e.g., between the anchor WTRUs). The set of anchor WTRUs (e.g., WTRU IDs) used to determine the WTRU's location may be reported (e.g., by the WTRU) along with the WTRU's absolute location and associated uncertainty metric (e.g., degree of uncertainty).

[0199] FIG. 5 shows an example signal flow diagram that may be applied to determining an anchor WTRU based on measurements and an uncertainty metric.

[0200] An out-of-coverage scenario may be associated with the anchor WTRU's decision.

[0201] FIG. 6 shows an example of anchor WTRU selection for an out-of-coverage scenario.

[0202] In an example, a positioning method and selection criteria (e.g., a degree of uncertainty lower than a threshold) for the anchor WTRU may be pre-configured (e.g., on the target WTRU). The anchor WTRU may be discovered (e.g., by the target WTRU) and a positioning request may be sent (e.g., by the target WTRU). Assistance information may be received (e.g., by the target WTRU from the anchor WTRU). A decision may be made (e.g., by the target WTRU) to use the anchor WTRU based on a degree of uncertainty associated with the absolute position (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 selection may be sent (e.g., by the target WTRU to the anchor WTRU). Resource allocation information (e.g., for SL-PRS) may be received (e.g., by the target WTRU from the anchor WTRU) (e.g., a Mode 2 allocation indicating time and / or frequency resources to be used for SL-PRS transmission). Measurements (e.g., related to SL-PRS) may be performed (e.g., by the target WTRU). The absolute location of the target WTRU may be determined (e.g., by the target WTRU) based on measurements (e.g., measurements made on the SL-PRS sent by the anchor WTRU). An uncertainty metric may be determined (e.g., by the target WTRU) based on an uncertainty metric associated with the absolute location of the anchor WTRU. Once the target WTRU comes into coverage, the absolute location (e.g., of the target WTRU) and associated uncertainty metric may be returned, as well as information related to the anchor WTRU to be used for SL positioning.

[0203] While features and elements are described above in particular combinations, those skilled in the art will understand that each feature or element can be used alone or in any combination with the other features and elements. Additionally, the methods described herein can be implemented in a computer program, software, or firmware embodied in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted via wired or wireless connections) 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 internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks and digital versatile disks (DVDs). A processor in association with software may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

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

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

3. 2. The target WTRU of claim 1, wherein the processor is configured to determine the target WTRU absolute location using a sidelink positioning method, on the condition that the selected anchor WTRU exceeds a threshold number of the anchor WTRUs.

4. 4. The target WTRU of claim 3, wherein 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, provided that the selected anchor WTRU exceeds a threshold number of the anchor WTRUs.

5. On the condition that the selected anchor WTRU is equal to or greater than a threshold number of the anchor WTRUs, the processor: The target WTRU of claim 3 , configured to determine the target WTRU absolute location using a combination of the sidelink positioning method and the default positioning method.

6. The processor:

4. The target WTRU of claim 3, further configured to accumulate the uncertainty metric based on a plurality of uncertainty metrics associated with each of the selected anchor WTRUs, provided that the target WTRU absolute location is determined using the sidelink positioning method.

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

8. The processor: The target WTRU of claim 1, further configured to: transmit, to the network node, information related to the selected anchor WTRU used for positioning, on the condition that the target WTRU enters network coverage, the information including identification information of the selected anchor WTRU.

9. The processor: receiving configuration information indicating either the default positioning method, the error threshold, or a threshold number of the anchor WTRUs; The target WTRU of claim 1 , further configured to determine the candidate anchor WTRUs and the respective uncertainty metrics from each of the candidate anchor WTRUs.

10. 1. A method for a target wireless transmit / receive unit (WTRU), comprising: selecting one or more anchor WTRUs from the candidate anchor WTRUs based on an uncertainty metric from said one or more anchor WTRUs being below an error threshold; determining a target WTRU absolute location and a target WTRU uncertainty metric, the method comprising: determining the target WTRU absolute location using a default positioning method, provided that the selected anchor WTRU is below a threshold number of anchor WTRUs; determining the target WTRU uncertainty metric, wherein the target WTRU uncertainty metric comprises either the uncertainty of the target WTRU or a degree of uncertainty of the target WTRU; transmitting to a network node an indication of the target WTRU absolute location and the target WTRU uncertainty metric.

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

12. 11. The method of claim 10, further comprising determining the target WTRU absolute location using a sidelink positioning method on the condition that the selected anchor WTRU exceeds a threshold number of the anchor WTRUs.

13. 13. The method of claim 12, wherein 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, provided that the selected anchor WTRU exceeds a threshold number of the anchor WTRUs.

14. On the condition that the selected anchor WTRU is equal to or greater than a threshold number of the anchor WTRUs, the method further comprises: The method of claim 12 , further comprising: determining the target WTRU absolute position using a combination of the sidelink positioning method and the default positioning method.

15. The method comprises:

13. The method of claim 12, further comprising: accumulating the uncertainty metric based on a plurality of uncertainty metrics associated with each of the selected anchor WTRUs, provided that the target WTRU absolute location is determined using the sidelink positioning method.

16. The method comprises:

11. The method of claim 10, further comprising: resetting the target WTRU uncertainty metric to the uncertainty associated with the default positioning method, provided that the target WTRU absolute position is determined using the default positioning method.

17. The method comprises:

11. The method of claim 10, further comprising: transmitting, to the network node, information related to the selected anchor WTRU used for positioning, on the condition that the target WTRU enters network coverage, the information including an identification of the selected anchor WTRU.

18. The method comprises: receiving configuration information indicating either the default positioning method, the error threshold, or a threshold number of the anchor WTRUs; The method of claim 10, further comprising: determining the candidate anchor WTRUs and the respective uncertainty metrics from each of the candidate anchor WTRUs.

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