Method and system for positioning group monitoring and maintenance

Abstract

A target wireless transmit / receive unit (WTRU) may receive a first sidelink positioning reference signal (SL-PRS) from an anchor WTRU. The target WTRU may determine a signal quality of the first SL-PRS. The target WTRU may transmit the second SL-PRS to the anchor WTRU. The target WTRU may receive the SL-PRS measurement report from the anchor WTRU. The SL-PRS measurement report may be based on a second SL-PRS transmitted to the anchor WTRU. The target WTRU may determine that the anchor WTRU is applicable to sidelink link-based positioning, e.g., based on a signal quality of a first SL-PRS received from the anchor WTRU and / or an SL-PRS measurement report. The target WTRU may determine a location of the target WTRU using the anchor WTRU.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 421,853, filed on November 2, 2022, the entire content of which is incorporated herein by reference. Background Art

[0003] Mobile communication using wireless communication is constantly evolving. More specifically, sidelink communication between devices is also evolving.

[0004] In NR V2X, the resources for sidelink transmission / reception can be constructed as resource pools. The resource pools can consist of a set of consecutive frequency resources that repeat over time according to a bitmap pattern. A wireless transmit / receive unit (WTRU) can be configured with one or more resource pools. For a WTRU within coverage, the resource pool can be configured via SIB / RRC. For a WTRU outside coverage, the resource pool can be configured. Summary of the Invention

[0005] Systems and methods for positioning group monitoring and maintenance are disclosed. For example, a WTRU can perform link - based sidelink position monitoring. The WTRU can determine which one of one or more WTRUs performs link - based sidelink position monitoring. In some examples, the determined WTRU can include the WTRU that makes the determination.

[0006] The WTRU can determine whether to initiate a sidelink positioning monitoring process. In some embodiments, the WTRU can determine the suitability of a link for sidelink positioning. The WTRU can make the suitability based on a received sidelink positioning reference signal (SL - PRS). In other embodiments, the WTRU can make the suitability of the link for sidelink positioning based on receiving a sidelink transmission. In some embodiments, the suitability can be based on a measurement report.

[0007] The WTRU can evaluate a link based on one or more link quality metrics. The one or more link quality metrics can be selected for link - based sidelink position monitoring. Additionally or alternatively, the WTRU can determine a time to evaluate the suitability of the link. In some embodiments, the WTRU can trigger one or more sidelink transmissions. The one or more sidelink transmissions can be used for sidelink positioning monitoring.

[0008] In some examples, a WTRU may determine whether to form a positioning group. Additionally or alternatively, a WTRU may determine whether to monitor a link in the group. The link may be associated with another WTRU. In some embodiments, a WTRU may determine whether one or more positioning groups are applicable for sidelink positioning. A WTRU may determine a time to evaluate the applicability of the one or more positioning groups. A WTRU may determine that the link is LPSUP (Link Permanently Unavailable for Sidelink Positioning). Additionally or alternatively, a WTRU may trigger an LPUSP timer. In some embodiments, a WTRU may determine that the group is GPUSP (Group Permanently Unavailable for Sidelink Positioning). Additionally or alternatively, a WTRU may trigger a GPUSP timer. In some embodiments, a WTRU may receive an indication for sidelink positioning monitoring from a node. A WTRU may select one or more additional or alternative WTRUs for one or more positioning sessions.

[0009] The WTRU may include a processor and a memory. The processor and the memory may be configured to establish a connection with an anchor WTRU for sidelink link-based positioning. The processor and the memory may be configured to: receive an indication of a positioning method type; determine a link quality metric of a connection between the WTRU and the anchor WTRU based on the positioning method type; determine the applicability of the anchor WTRU for sidelink link-based positioning based on the link quality metric, and use the anchor WTRU for sidelink link-based positioning to determine the location of the WTRU.

[0010] When the positioning method type is based on round-trip time (RTT), the link quality metric may include sidelink positioning reference signal (SL-PRS) reception and an SL-PRS measurement report. When the positioning method type is based on sidelink positioning reference signal reception (SL-PRS Rx), the link quality metric may include SL-PRS reception. When the positioning method type is based on sidelink positioning reference signal transmission (SL-PRS Tx), the link quality metric may include an SL-PRS measurement report.

[0011] In some embodiments, when the positioning method type is based on RTT, one or more of the memory and the processor may be configured to perform one or more of the following: transmit a sidelink positioning reference signal to the anchor WTRU; receive a sidelink positioning reference signal from the anchor WTRU; and receive an SL-PRS measurement report from the anchor WTRU based on the sidelink positioning reference signal transmitted to the anchor WTRU. The link quality metric may include, for example, the SL-PRS and the SL-PRS measurement report received from the anchor WTRU.

[0012] In some embodiments, when the positioning method type is based on SL-PRS Rx, the WTRU may be configured to receive sidelink positioning reference signals from an anchor WTRU. The link quality metric may include, for example, the SL-PRS received from the anchor WTRU.

[0013] For example, the WTRU may also be configured to: establish a connection with a second anchor WTRU for sidelink link-based positioning; determine a second link quality metric for the connection between the WTRU and the second anchor WTRU based on the positioning method type; determine the suitability of the second anchor WTRU for sidelink link-based positioning based on the second link quality metric; and use the second anchor WTRU for sidelink link-based positioning to determine the location of the WTRU. In some embodiments, the suitability of the anchor WTRU and the second anchor WTRU for sidelink link-based positioning may be determined independently.

[0014] In some embodiments, the WTRU may be configured to receive positioning reference signals during an evaluation period. The suitability of the anchor WTRU for sidelink link-based positioning may be determined, for example, during the evaluation period. In some embodiments, the WTRU may be configured to determine whether the value of a non-suitability indication exceeds a non-suitability threshold. Based on the value of the non-suitability indication exceeding the non-suitability threshold, the WTRU may, for example, perform one or more of the following: send a link persistently unavailable for sidelink positioning (LPUSP) indication to one or more nodes; release one or more links; and stop a sidelink positioning session.

[0015] A target wireless transmit / receive unit (WTRU) may receive a first sidelink positioning reference signal (SL-PRS) from an anchor WTRU. The target WTRU may determine the signal quality of the first SL-PRS. The target WTRU may transmit a second SL-PRS to the anchor WTRU. The target WTRU may receive an SL-PRS measurement report from the anchor WTRU. The SL-PRS measurement report may be based on the second SL-PRS transmitted to the anchor WTRU. The target WTRU may determine that the anchor WTRU is suitable for sidelink link-based positioning, for example, based on the signal quality of the first SL-PRS and / or the SL-PRS measurement report received from the anchor WTRU. The target WTRU may use the anchor WTRU to determine the location of the target WTRU.

[0016] The target WTRU may determine that the anchor WTRU is suitable for sidelink link-based positioning, e.g., when the signal quality of the first SL-PRS is greater than a first threshold and / or the SL-PRS measurement report indicates that the signal quality of the second SL-PRS transmitted to the anchor WTRU is greater than a second threshold. The first threshold and / or the second threshold may be within a configured range and / or a predetermined range. The target WTRU may determine that the anchor WTRU is not suitable for link-based positioning, e.g., when the signal quality of the first SL-PRS is less than the first threshold, the SL-PRS measurement report indicates that the signal quality of the second SL-PRS transmitted to the anchor WTRU is less than the second threshold, the second SL-PRS is not transmitted to the anchor WTRU, the first SL-PRS from the anchor WTRU is not received, and / or the SL-PRS measurement report is not received.

[0017] The target WTRU may determine that the anchor WTRU is not suitable for link-based positioning for a certain number of consecutive periods. The target WTRU may transmit a link persistently unavailable for sidelink positioning (LPUSP) indication, e.g., based on the number of consecutive periods exceeding a third threshold. The target WTRU may stop the sidelink positioning session with the anchor WTRU. One (e.g., each) of the number of consecutive periods may include receiving the first SL-PRS, transmitting the second SL-PRS, and / or receiving the SL-PRS measurement report. The LPUSP may be transmitted to one or more of the following: the anchor WTRU and / or the Location Management Function (LMF). The signal quality of the first SL-PRS may include one or more of the following: a Line-of-Sight (LOS) value and / or a Non-Line-of-Sight (NLOS) value. The target WTRU may receive an indication to perform sidelink positioning monitoring. The target WTRU may transmit an indication to perform sidelink positioning monitoring to another WTRU.

[0018] The target WTRU may receive an SL-PRS measurement report from each anchor WTRU in the sidelink positioning group. The SL-PRS measurement report may be based on the SL-PRS transmitted to each anchor WTRU in the sidelink positioning group. The measurement report may include an indication of one or more of the following: the distance between the WTRU and the corresponding anchor WTRU and / or the direction between the WTRU and the corresponding anchor WTRU. For example, if the anchor WTRU moves out of the sidelink positioning group, the target WTRU may determine whether to maintain or terminate the sidelink positioning group.

[0019] The target WTRU may determine the signal quality of the SL-PRS received from each anchor WTRU of the sidelink positioning group. The target WTRU may transmit the SL-PRS to each anchor WTRU of the sidelink positioning group. The target WTRU may receive an SL-PRS measurement report from each anchor WTRU of the sidelink positioning group, e.g., based on the SL-PRS transmitted to the anchor WTRU. The target WTRU may determine whether each anchor WTRU of the sidelink positioning group is suitable for sidelink positioning. This determination may be based on the signal quality of the SL-PRS received from the corresponding anchor WTRU and / or the SL-PRS measurement report received from the corresponding anchor WTRU.

[0020] The target WTRU may determine whether the sidelink positioning group is suitable for sidelink positioning, e.g., based on whether the number of anchor WTRUs in the sidelink positioning group that are suitable for sidelink positioning exceeds a threshold. The target WTRU may determine the location of the target WTRU, e.g., based on the number of anchor WTRUs in the sidelink positioning group that are suitable for sidelink positioning exceeding the threshold, and use the sidelink positioning group to determine the location of the target WTRU. The target WTRU may determine that the sidelink positioning group is not suitable for multiple consecutive periods. The target WTRU may send a "Group Persistently Unavailable for Sidelink Positioning (GPUSP)" indication to one or more devices. The GPUSP indication may be sent by the target WTRU to, e.g., a network device and / or an anchor WTRU of the sidelink positioning group. The signal quality may include sidelink received signal received power (SL-RSRP). Brief Description of the Drawings

[0021] Figure 1A is a system diagram of an illustrative example communication system in which one or more of the disclosed embodiments may be implemented.

[0022] Figure 1B is illustrative of an example wireless transmit / receive unit (WTRU) that may be used within the Figure 1A communication system shown in.

[0023] Figure 1C is illustrative of an example radio access network (RAN) and an example core network (CN) that may be used within the Figure 1A communication system shown in.

[0024] Figure 1D is illustrative of another example RAN and another example CN that may be used within the Figure 1A communication system shown in.

[0025] Figure 2It is an example diagram illustrating the radio link monitoring (RLM) and radio link failure (RLF) processes.

[0026] Figure 3 It is a flowchart illustrating an example process of link-based sidelink positioning monitoring.

[0027] Figure 4 It is a flowchart illustrating an example process of group-based sidelink positioning monitoring.

[0028] Figure 5 It is a flowchart illustrating an example process of link-based sidelink positioning monitoring. Specific embodiments

[0029] Figure 1A It is a diagram illustrating an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multi-access system that provides content, such as voice, data, video, messages, broadcasts, etc., to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content by sharing system resources, including wireless bandwidth. For example, the communication system 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), zero-tail unique word DFT-spread OFDM (ZT UWDTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM (OFDM), filter bank multicarrier (FBMC), etc.

[0030] As Figure 1AAs shown in FIG. 0, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104 / 113, a core network (CN) 106 / 115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, but it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the 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), mobile stations, fixed or mobile subscriber units, subscription-based units, pagers, cellular telephones, personal digital assistants (PDAs), smart phones, laptop computers, netbooks, personal computers, wireless sensors, hotspots or Mi-Fi devices, Internet of Things (IoT) devices, watches or other wearable devices, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated processing chain environment), consumer electronic devices, devices operating on commercial and / or industrial wireless networks, etc. Any one of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0031] The communication system 100 may also include base stations 114a and / or base stations 114b. Each of the base stations 114a and 114b may be any type of device configured to perform the following operations: wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106 / 115, the Internet 110, and / or other networks 112. For example, the base stations 114a and 114b may be base transceiver stations (BTSs), Node-Bs, eNode Bs, home Node Bs, home eNode Bs, gNBs, NR Node Bs, site controllers, access points (APs), wireless routers, etc. Although the base stations 114a, 114b are each depicted as a single element, it should be understood that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0032] Base station 114a may be part of the RAN 104 / 113, which may also include other base stations and / or network elements (not shown in the figure), such as a base station controller (BSC), a radio network controller (RNC), a relay node, etc. Base station 114a and / or base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as cells (not shown in the figure). These frequencies may be in the licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide wireless service coverage for a specific geographical area, which may be relatively fixed or may change over time. A cell may be further divided into cell sectors. For example, the cell associated with base station 114a may be divided into three sectors. Thus, in one embodiment, base station 114a may include three transceivers, i.e., one for each sector of the cell. In an embodiment, base station 114a may employ multiple-input multiple-output (MIMO) technology and may use multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and / or receive signals in the desired spatial direction.

[0033] Base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d via an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, millimeter wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0034] More specifically, as described above, the communication system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, base station 114a in the RAN 104 / 113 and WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may use Wideband CDMA (WCDMA) to establish the air interfaces 115 / 116 / 117. WCDMA may include communication protocols such as High Speed Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed Downlink (DL) Packet Access (HSDPA) and / or High Speed UL Packet Access (HSUPA).

[0035] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as evolved UMTS terrestrial radio access (E-UTRA), which may use Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-Advanced Pro (LTE-A Pro) to establish an air interface 116.

[0036] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR radio access, which may use New Radio (NR) to establish an air interface 116.

[0037] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access simultaneously, for example, using the dual connectivity (DC) principle. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions to / from multiple types of base stations (e.g., eNBs and gNBs).

[0038] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wi-Fi), 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 Rate for GSM Evolution (EDGE), GSM EDGE (GERAN), etc.

[0039] Figure 1AThe base station 114b therein may be, for example, a wireless router, a home Node B, a home eNode B, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in a local area such as a commercial venue, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for 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 an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a picocell or a femto cell. As Figure 1A shown, the base station 114b may be directly connected to the Internet 110. Thus, the base station 114b may access the Internet 110 without going through the CN 106 / 115.

[0040] The RAN 104 / 113 may communicate with the CN 106 / 115, which may be any type of network configured to perform the following operations: providing voice, data, applications, and / or voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, fault tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 may provide call control, billing services, location-based services based on mobility, prepaid calls, Internet connectivity, video distribution, etc., and / or perform advanced security functions such as user authentication. Although Figure 1A not shown, it should be understood that the RAN 104 / 113 and / or the CN 106 / 115 may communicate directly or indirectly with other RANs that employ the same or a different RAT as the RAN 104 / 113. For example, in addition to being connected to the RAN 104 / 113 that may utilize the NR radio technology, the CN 106 / 115 may also communicate with another RAN (not shown in the figure) that employs a GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0041] CN 106 / 115 may also act as a gateway for the WTRU 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides Plain Old Telephone Service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols (such as the Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and / or Internet Protocol (IP) in 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. For example, the network 112 may include another CN connected to one or more RANs, and these RANs may employ the same or different RATs as the RAN 104 / 113.

[0042] Some or all of the WTRU 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities (e.g., the WTRU 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks via different wireless links). For example, Figure 1A the WTRU 102c shown in may be configured to communicate with a base station 114a that may employ a cellular-based radio technology and a base station 114b that may employ an IEEE 802 radio technology.

[0043] Figure 1B is a system diagram of an illustrative example of the WTRU 102. As Figure 1B shown, the WTRU 102 may include a processor 118, a transceiver 120, transmit / receive elements 122, a speaker / microphone 124, a keyboard 126, a display / touchpad 128, a non-removable memory 130, a removable memory 132, a power supply 134, a Global Positioning System (GPS) chipset 136, and / or other peripheral devices 138, etc. It should be understood that, while remaining consistent with the embodiment, the WTRU 102 may include any sub-combination of the above elements.

[0044] The processor 118 can be a general-purpose processor, a dedicated 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 can perform signal encoding / decoding, data processing, power control, input / output processing, and / or any other functions that enable the WTRU 102 to operate in a wireless environment. The processor 118 can be coupled to a transceiver 120, and the transceiver 120 can be coupled to a transmit / receive element 122. Although Figure 1B the processor 118 and the transceiver 120 are depicted as separate components, it should be understood that the processor 118 and the transceiver 120 can be integrated together in an electronic package or chip.

[0045] The transmit / receive element 122 can be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) via an air interface 116. For example, in one embodiment, the transmit / receive element 122 can be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmit / receive element 122 can be a transmitter / detector configured to transmit and / or receive signals such as IR, UV, or visible light signals. In yet another embodiment, the transmit / receive element 122 can be configured to transmit and / or receive both RF signals and optical signals. It should be understood that the transmit / receive element 122 can be configured to transmit and / or receive any combination of wireless signals.

[0046] Although Figure 1B the transmit / receive element 122 is depicted as a single element in the figure, the WTRU 102 can include any number of transmit / receive elements 122. More specifically, the WTRU 102 can employ MIMO technology. Thus, in one embodiment, the WTRU 102 can include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals via the air interface 116.

[0047] The transceiver 120 can be configured to modulate the signals to be transmitted by the transmit / receive element 122 and demodulate the signals received by the transmit / receive element 122. As described above, the WTRU 102 can have multi-mode capabilities. Thus, the transceiver 120 can include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs (such as, for example, NR and IEEE 802.11).

[0048] The processor 118 of the WTRU 102 can be coupled to the speaker / microphone 124, the keyboard 126, and / or the display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit), and can receive user input data from these devices. The processor 118 can also output user data to the speaker / microphone 124, the keyboard 126, and / or the display / touchpad 128. Additionally, the processor 118 can 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 can include random access memory (RAM), read only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 can include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, etc. In other embodiments, the processor 118 can access information from and store data in a memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0049] The processor 118 can receive power from a power supply 134 and can be configured to distribute power to and / or control the power going to other components in the WTRU 102. The power supply 134 can be any device suitable for powering the WTRU 102. For example, the power supply 134 can include one or more dry cells (e.g., nickel cadmium (NiCd), nickel zinc (NiZn), nickel metal hydride (NiMH), lithium ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0050] The processor 118 can also be coupled to a GPS chipset 136, which can be configured to provide location information (e.g., longitude and latitude) about the current location of the WTRU 102. In addition to or in place of the information from the GPS chipset 136, the WTRU 102 can receive location information from a base station (e.g., base stations 114a, 114b) via an air interface 116, and / or can determine its location based on the timing of signals received from two or more nearby base stations. It should be understood that the WTRU 102 can obtain location information by any suitable location determination method while remaining consistent with the embodiments.

[0051] The processor 118 can also be coupled to other peripheral devices 138, which can include one or more software and / or hardware modules that provide additional features, functions, and / or wired or wireless connections. For example, the peripheral devices 138 can 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, Modules, FM radio units, digital music players, media players, video game player modules, Internet browsers, virtual reality and / or augmented reality (VR / AR) devices, activity trackers, etc. Peripheral device 138 may include one or more sensors, which may be one or more of the following: gyroscopes, accelerometers, Hall effect sensors, magnetometers, orientation sensors, proximity sensors, temperature sensors, time sensors, geographical location sensors; altimeters, light sensors, touch sensors, magnetometers, barometers, gesture sensors, biosensors, and / or humidity sensors.

[0052] The WTRU 102 may include a full-duplex radio, for which the transmission and reception of some or all signals (e.g., signals associated with a specific subframe for both UL (e.g., for transmission) and downlink (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit for reducing and / or substantially eliminating self-interference via hardware (e.g., chokes) or signal processing by a processor (e.g., a separate processor (not shown) or by processor 118). In an embodiment, the WRTU 102 may include a half-duplex radio, for which the transmission and reception of some or all signals (e.g., signals associated with a specific subframe for UL (e.g., for transmission) or downlink (e.g., for reception)).

[0053] Figure 1C Is a system diagram of the RAN 104 and the CN 106 according to an embodiment. As described above, the RAN 104 may employ E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c via the air interface 116. The RAN 104 may also communicate with the CN 106.

[0054] The RAN 104 may include eNodeBs 160a, 160b, 160c, but it should be understood that, consistent with the embodiment, the RAN 104 may include any number of eNodeBs. The eNodeBs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c via the air interface 116. In one embodiment, the eNodeBs 160a, 160b, 160c may implement MIMO technology. Thus, for example, the eNodeB160a may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0055] Each of eNodeBs 160a, 160b, and 160c can be associated with a specific cell (not shown in the figure) and can be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and / or DL, etc. As Figure 1C shown, eNodeBs 160a, 160b, and 160c can communicate with each other via the X2 interface.

[0056] Figure 1C The CN 106 shown in can 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 above elements is depicted as part of the CN 106, it should be understood that any of these elements can be owned and / or operated by an entity other than the CN operator.

[0057] The MME 162 can be connected to each of the eNodeBs 162a, 162b, 162c in the RAN 104 via the S1 interface and can act as a control node. For example, the MME 162 can be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a specific serving gateway during the initial attachment of the WTRUs 102a, 102b, 102c, etc. The MME 162 can provide control plane functions for handover between the RAN 104 and other RANs (not shown) employing other radio technologies such as GSM and / or WCDMA.

[0058] The SGW 164 can be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 104 via the S1 interface. The SGW 164 can generally route and forward user data packets to and from the WTRUs 102a, 102b, 102c. The SGW 164 can perform other functions such as anchoring the user plane during handover between eNode Bs, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, etc.

[0059] The SGW 164 can be connected to the PGW 166, and the PGW 166 can provide the WTRUs 102a, 102b, 102c with access to a packet switched network such as the Internet 110 to facilitate communication between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0060] CN 106 can facilitate communication with other networks. For example, CN 106 can provide the WTRUs 102a, 102b, 102c with access to a circuit-switched network (such as the PSTN 108) to facilitate communication between the WTRUs 102a, 102b, 102c and traditional landline communication devices. For example, CN 106 can include, or communicate with, an IP gateway (such as an IP Multimedia Subsystem (IMS) server), which serves as an interface between CN 106 and the PSTN 108. In addition, CN 106 can provide the WTRUs 102a, 102b, 102c with access to other networks 112, which can include other wired and / or wireless networks owned and / or operated by other service providers.

[0061] Although the WTRU is described as a wireless terminal in Figure 1A - 1D , it is contemplated that in certain representative embodiments, such a terminal can communicate with a communication network using (e.g., temporarily or permanently) a wired communication interface.

[0062] In a representative embodiment, another network 112 can be a WLAN.

[0063] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP can access or interface to a distribution system (DS) or another type of wired / wireless network that carries traffic to and from the BSS. Traffic destined for an STA from outside the BSS can arrive at the AP and can be delivered to the STA. Traffic originating from an STA destined for a destination outside the BSS can be sent to the AP for delivery to the corresponding destination. Traffic between STAs within the BSS can be sent through, for example, the AP, where the source STA can send the traffic to the AP and the AP can deliver the traffic to the destination STA. Traffic between STAs within the BSS can be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic can be sent between the source STA and the destination STA using direct link setup (DLS) (e.g., directly between the source STA and the destination STA). In certain representative embodiments, DLS can use 802.11e DLS or 802.11z tunneled DLS (TDLS). A WLAN using independent BSS (IBSS) mode may not have an AP, and STAs within the IBSS or using the IBSS (e.g., all STAs) can communicate directly with each other. The IBSS communication mode can sometimes be referred to in this document as an "ad-hoc" communication mode.

[0064] When operating in 802.11ac infrastructure mode or a similar mode of operation, the AP can transmit beacons on a fixed channel, such as the primary channel. The primary channel can be of a fixed width (e.g., a bandwidth of 20 MHz width), or can be of a width dynamically set via signaling. The primary channel can be the operating channel of the BSS and can be used by the STA to establish a connection with the AP. In some representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) can be implemented, such as in 802.11 systems. For CSMA / CA, all STAs including the AP (e.g., each STA) can listen to the primary channel. If a particular STA listens / detects and / or determines that the primary channel is busy, that particular STA can back off. One STA (e.g., only one station) can transmit at any given time in a given BSS.

[0065] High Throughput (HT) STAs can communicate using a 40 MHz wide channel, e.g., by combining the primary 20 MHz channel with an adjacent or non - adjacent 20 MHz channel to form a 40 MHz wide channel.

[0066] Very High Throughput (VHT) STAs can support 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels. 40 MHz and / or 80 MHz channels can be formed by combining consecutive 20 MHz channels. A 160 MHz channel can be formed by combining eight consecutive 20 MHz channels or by combining two non - consecutive 80 MHz channels (which can be referred to as an 80 + 80 configuration). For the 80 + 80 configuration, after channel coding, the data can be passed through a segment parser that can divide the data into two streams. The inverse Fast Fourier Transform (IFFT) processing and time - domain processing can be performed separately on each stream. The streams can be mapped to two 80 MHz channels and the data can be transmitted by the transmitting STA. At the receiver of the receiving STA, the operations for the 80 + 80 configuration can be reversed and the combined data can be sent to the Medium Access Control (MAC).

[0067] 802.11af and 802.11ah support operation modes below 1 GHz. The channel operation bandwidth and carriers in 802.11af and 802.11ah are reduced 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 uses the non-TVWS spectrum to support 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths. According to a representative embodiment, 802.11ah may support Meter Type Control / Machine-Type Communications, such as MTC devices in a macro coverage area. MTC devices may have specific capabilities, for example, including limited functionality that supports (e.g., only supports) specific and / or limited bandwidths. MTC devices may include a battery with a battery life higher than a threshold (e.g., maintaining a very long battery life).

[0068] WLAN systems (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) that can support multiple channels and channel bandwidths include channels that can be designated as primary channels. The bandwidth of the primary channel may be equal to the maximum common operation bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or restricted by the STA that supports the minimum bandwidth operation mode among all STAs operating in the BSS. Taking 802.11ah as an example, for an STA that supports (e.g., only supports) the 1 MHz mode (e.g., an MTC type device), the primary channel bandwidth may be 1 MHz, even if the AP and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operation modes. Carrier sensing and / or network allocation vector (NAV) settings may depend on the state of the primary channel. If the primary channel is busy (e.g., due to an STA that only supports the 1 MHz operation mode) transmitting to the AP, the entire available frequency band may be considered busy, even if most of the frequency band remains idle and may be available.

[0069] In the United States, the available frequency band that 802.11ah can use is 902 MHz to 928 MHz. In Korea, the available frequency band is 917.5 MHz to 923.5 MHz. In Japan, the available frequency band is 916.5 MHz to 927.5 MHz. The total bandwidth available for 802.11ah is 6 MHz to 26 MHz, depending on the country code.

[0070] Figure 1DFIG. is a system diagram of RAN 113 and CN 115 according to an embodiment. As described above, RAN 113 may communicate with WTRUs 102a, 102b, 102c via air interface 116 using NR radio technology. RAN 113 may also communicate with CN 115.

[0071] RAN 113 may include gNBs 180a, 180b, 180c, but it should be understood that RAN 113 may include any number of gNBs while remaining consistent with the embodiment. gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with WTRUs 102a, 102b, 102c via air interface 116. In one embodiment, GNBs 180a, 180b, 180c may implement MIMO technology. For example, gNBs 180a, 180b may use beamforming to transmit signals to and / or receive signals from gNBs 180a, 180b, 180c. Thus, for example, gNB 180a may use multiple antennas to transmit wireless signals to and / or receive wireless signals from WTRU 102a. In an embodiment, gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, gNB 180a may transmit multiple component carriers to WTRU 102a (not shown). A subset of these component carriers may be located in the unlicensed spectrum, while the remaining component carriers may be located in the licensed spectrum. In an embodiment, gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0072] WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using transmissions associated with scalable parameter sets. For example, the OFDM symbol interval and / or the OFDM subcarrier interval may vary for different transmissions, different cells, and / or different parts of the radio transmission spectrum. WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using various or scalable length subframes or transmission time intervals (TTIs) (e.g., containing different numbers of OFDM symbols and / or having different absolute time lengths of duration).

[0073] gNBs 180a, 180b, 180c can be configured to communicate with WTRUs 102a, 102b, 102c in stand-alone configuration and / or non-stand-alone configuration. In stand-alone configuration, WTRUs 102a, 102b, 102c can communicate with gNBs 180a, 180b, 180c without also accessing another RAN (e.g., such as eNode-Bs 160a, 160b, 160c). In stand-alone configuration, WTRUs 102a, 102b, 102c can utilize one or more of gNBs 180a, 180b, 180c as a mobility anchor. In stand-alone configuration, WTRUs 102a, 102b, 102c can communicate with gNBs 180a, 180b, 180c using signals in the unlicensed band. In non-stand-alone configuration, WTRUs 102a, 102b, 102c can communicate / connect with gNBs 180a, 180b, 180c while also communicating / connecting with another RAN (such as eNode-Bs 160a, 160b, 160c). For example, WTRUs 102a, 102b, 102c can implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In non-stand-alone configuration, eNode-Bs 160a, 160b, 160c can act as the mobility anchor for WTRUs 102a, 102b, 102c, while gNBs 180a, 180b, 180c can provide additional coverage and / or throughput for serving WTRUs 102a, 102b, 102c.

[0074] Each of gNBs 180a, 180b, 180c can be associated with a specific cell (not shown in the figure) and can be configured to handle radio resource management decisions, handover decisions, user scheduling in UL and / or DL, network slice support, dual connectivity, interworking between NR and E-UTRA, routing user plane data to user plane functions (UPFs) 184a, 184b, routing control plane information to access and mobility management functions (AMFs) 182a, 182b, etc. As Figure 1D shown, gNBs 180a, 180b, 180c can communicate with each other via the Xn interface.

[0075] Figure 1DAs shown in , CN 115 may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and may include data networks (DN) 185a, 185b. Although each of the above elements is depicted as part of CN 115, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0076] AMF 182a, 182b may be connected to one or more of gNB 180a, 180b, 180c in RAN 113 via the N2 interface and may act as a control node. For example, AMF 182a, 182b may be responsible for authenticating users of WTRU 102a, 102b, 102c, supporting network slicing (e.g., handling different PDU sessions with different requirements), selecting a specific SMF 183a, 183b, managing the registration area, terminating NAS signaling, mobility management, etc. AMF 182a, 182b may use network slicing to customize the CN support for WTRU 102a, 102b, 102c based on the service type used by WTRU 102a, 102b, 102c. For 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.). AMF 162 may provide control plane functions for handover between RAN 113 and other RANs (not shown in the figure) employing other radio technologies (such as LTE, LTE-A, LTE-A Pro) and / or non-3GPP access technologies (such as WiFi).

[0077] SMF 183a, 183b may be connected to AMF 182a, 182b in CN 115 via the N11 interface. SMF 183a, 183b may also be connected to UPF 184a, 184b in CN 115 via the N4 interface. SMF 183a, 183b may select and control UPF 184a, 184b and configure the traffic routing through UPF 184a, 184b. SMF 183a, 183b may perform other functions such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0078] UPF 184a and 184b can be connected to one or more of gNBs 180a, 180b, 180c in the RAN 113 via the N3 interface. The N3 interface can provide the WTRUs 102a, 102b, 102c with access to a packet switched network (such as the Internet 110) to facilitate communication between the WTRUs 102a, 102b, 102c and IP-enabled devices. UPF 184a and 184b can perform other functions, such as routing and forwarding data packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink data packets, providing mobility anchoring, and so on.

[0079] The CN 115 can facilitate communication with other networks. For example, the CN 115 can include an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server), or can communicate with the IP gateway that serves as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 can provide the WTRUs 102a, 102b, 102c with access to other networks 112, which can include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c can be connected to local data networks (DNs) 185a, 185b via the UPF 184a, 184b through the N3 interface to the UPF 184a, 184b and the N6 interface between the UPF 184a, 184b and the DNs 185a, 185b.

[0080] In view of Figure 1A - 1D and Figure 1A - 1D In view of the corresponding descriptions thereof, one or more or all of the functions described herein for one or more of the following can be performed by one or more emulation devices (not shown in the figures): WTRUs 102a-d, base stations 114a-b, eNode-Bs 160a-c, MME 162, SGW 164, PGW 166, gNBs 180a-c, AMF 182a-ab, UPFs 184a-b, SMFs 183a-b, DNs 185a-b, and / or any other (one or more) devices described herein. The emulation devices can be one or more devices configured to emulate one or more or all of the functions described herein. For example, the emulation devices can be used to test other devices and / or simulate network and / or WTRU functions.

[0081] The simulation device can be designed to implement one or more tests on other devices in a laboratory environment and / or an operator network environment. For example, the one or more simulation devices can perform one or more or all functions when fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to test other devices within the communication network. The one or more simulation devices can perform one or more or all functions when temporarily implemented / deployed as part of a wired and / or wireless communication network. The simulation device can be directly coupled to another device for testing and / or can perform tests using over-the-air wireless communication.

[0082] One or more simulation devices can perform one or more (including all) functions without being implemented / deployed as part of a wired and / or wireless communication network. For example, the simulation device can be used in a test scenario in a test laboratory and / or an undeployed (e.g., test) wired and / or wireless communication network to implement tests on one or more components. One or more simulation devices can be test equipment. The simulation device can transmit and / or receive data using direct RF coupling and / or wireless communication via an RF circuit (e.g., which may include one or more antennas).

[0083] The sidelink transmission span within a time slot (e.g., each sidelink transmission span) can include one or more PSSCH and / or PSCCH transmissions. For example, PSSCH and / or PSCCH can use FDM and / or TDM multiplexing. The sidelink control information (SCI) can be divided into multiple parts. For example, the SCI can be divided into two parts. These two parts can include a first-stage SCI and a second-stage SCI. The first-stage SCI can indicate one or more of the following: resources for sidelink transmission, QoS (e.g., priority) of the transmission, DMRS, PTRS, and / or the second SCI format for sidelink transmission. The second-stage SCI can indicate the remaining control information. For example, the SCI can be used to reserve resources within a resource pool for future transmission.

[0084] The WTRU may be configured for sidelink transmission scheduling. Sidelink resources may be scheduled by the network (e.g., mode 1) and / or selected autonomously by the WTRU (e.g., mode 2). The WTRU may perform sensing by decoding the SCI from other WTRUs, e.g., in the case where the WTRU performs mode 2. Additionally or alternatively, the WTRU may select one or more sidelink resources (e.g., to avoid selecting resources reserved by other WTRUs), e.g., after performing sensing by decoding the SCI from other WTRUs. The systems and methods described herein may describe how the WTRU performs sensing and / or how resource selection is performed for sidelink data communication, e.g., for WTRU autonomous resource allocation (i.e., mode 2). The WTRU may be configured with a resource pool for sensing and / or resource allocation. The WTRU may perform sensing during a sensing window, e.g., for detecting transmissions and / or resource reservations from one or more other WTRUs (e.g., via SCI decoding). The WTRU may trigger resource selection to select resources for transmission, e.g., when data arrives. The WTRU may select a resource selection window (RSW). The RSW may be selected according to the packet delay budget (PDB). The WTRU may (e.g., first) determine which resources are reserved by one or more other WTRUs, and / or exclude these resources from the set of available resources, e.g., in the RSW. The WTRU may (e.g., then) select resources for transmission in the RSW. The resources may be selected from the set of available resources. For example, the WTRU may select resources for periodic and / or aperiodic transmission.

[0085] SL-CSI-RS may be supported for unicast. SL-CSI-RS may support the TxWTRU in determining Tx parameters (e.g., power and rank). The TxWTRU may indicate the presence of the SL-CSI-RS, e.g., by using the SCI. The CSI-RS transmission may trigger a CSI report. For example, the CSI report latency may be configured via PC5 RRC. One (e.g., each) report may be associated with one SL-CSI-RS transmission.

[0086] NRUu positioning can be one or more of the following: DL-based, UL-based, and / or DL and UL-based. One or more DL-PRSs can be sent from one or more TRPs to one or more WTRUs, such as in DL-based systems and methods. The WTRU can observe measurement results of the downlink signal. The WTRU can determine one or more positions of one or more WTRUs. The WTRU can send (e.g., return) one or more downlink measurement results to one or more networks. The positioning method and system can be based on angles. For example, the WTRU can report one or more angles of arrival (AoA). Additionally or alternatively, the WTRU can report one or more RSRPs of one or more signals. The one or more signals can include downlink signals. The one or more signals can come from one or more TRPs. Positioning can be based on timing. For example, the WTRU can report one or more RSTDs. There may be transmission timing synchronization between one or more TRPs. There may be positioning calculation errors. The positioning calculation errors can be at least partially based on one or more of the synchronization error and / or multipath.

[0087] Positioning can be based on UL. The WTRU can send one or more UL-PRSs. The one or more UL-PRSs can be used for positioning. The one or more UL-PRSs can be configured by RRC. The one or more UL-PRSs can be sent to one or more TRPs. One or more networks can determine or calculate one or more positions of one or more WTRUs. For example, the determination or calculation can be based on the coordination of one or more TRPs.

[0088] Positioning can be based on DL and / or UL. The WTRU can measure one or more Rx-Tx time differences. The one or more time differences can exist between one or more received DL-PRSs and / or transmitted UL-PRSs. The one or more Rx-Tx time differences can be reported to one or more networks. For example, the one or more networks can coordinate one or more TRPs. The coordination can be used to determine or calculate one or more positions of one or more WTRUs.

[0089] Figure 2FIG. 0 is an example diagram of a radio link monitoring (RLM) and radio link failure (RLF) process 200. For example, the radio link monitoring (RLM) and radio link failure (RLF) process may be performed over the Uu interface. RLM / RLF may be supported. RLM / RLF may monitor one or more Uu links. The one or more Uu links may be between one or more WTRUs and one or more gNBs. One or more WTRUs may be configured from one or more networks. The configuration may use one or more of SSB and / or CSI-RS. One or more of SSB and CSI-RS may monitor one or more links. For example, a WTRU may be configured with one or more in-sync (IS) / out-of-sync (OOS) indication periods 202, 204. During the one or more indication periods 202, 204, the WTRU may monitor one or more signals. The one or more signals may be one or more configured radio link monitoring reference signals (RM-RS). For example, the one or more RM-RS may be one or more of SSB and / or CSI-RS.

[0090] The WTRU may monitor the one or more signals. The monitoring may determine (e.g., for determining) whether one or more WTRUs are at least one of IS and / or OOS. For example, the WTRU may determine whether one or more WTRUs are at least one of IS and / or OOS. The WTRU may be configured with one or more thresholds. The one or more thresholds may include one or more BLER thresholds. The one or more BLER thresholds may be one or more of Qin and / or Qout. The one or more thresholds may be used to determine IS / OOS. For example, if the BLER of the RM-RS within an indication period is greater than Qout, the WTRU may determine OOS. As Figure 2 shown, for example at 206, the WTRU may be configured N310OOS. At 208, the WTRU may trigger at least one RLF timer T130. The triggering may be based on receiving one or more consecutive OOS indications (N310). Additionally or alternatively, the WTRU may declare RLF, for example after T310 expires at 210, and / or in the absence of N311 IS indication at 212.

[0091] The target WTRU may utilize one or more anchor WTRUs, e.g., in order to perform one or more of transmission / reception and measurement reporting. Additionally or alternatively, the target WTRU may utilize one or more anchor WTRUs for sidelink positioning. The transmission and / or reception may include SL-PRS. The measurement reporting may be used to locate one or more positions of one or more WTRUs. One or more links between the target WTRU and the one or more anchor WTRUs may vary dynamically. The applicability of the one or more anchor WTRUs to support the positioning of the target WTRU may vary dynamically (e.g., accordingly).

[0092] The QoS requirements for positioning may include one or more of positioning availability, latency, and / or accuracy. The target WTRU may periodically monitor the link condition and / or one or more of the links. The monitoring of one or more of the link condition and / or link quality may be performed between the target WTRU and the one or more anchor WTRUs. This monitoring may be used to handle the dynamic conditions between the WTRUs. This monitoring may assist the WTRU in adapting one or more sidelink positioning procedures. The one or more sidelink positioning procedures may determine (e.g., ensure) the QoS of the positioning service. For example, the QoS of the positioning service may be based on the one or more SL procedures. For example, the one or more procedures may perform one or more of minimizing positioning interruption and / or improving positioning accuracy.

[0093] The applicability of one or more of the links, WTRUs, and / or groups for sidelink positioning may describe how the one or more links, WTRUs, and / or groups are applicable in a positioning method or system to support one or more WTRUs. The applicability of one or more of the links, WTRUs, and / or groups may be a (e.g., hard) value. For example, the (e.g., hard) value may be (e.g., either) applicable or not applicable. In some embodiments, the applicability of one or more of the links, WTRUs, and / or groups may be a soft value. For example, the soft value may be a value between applicable and not applicable. Applicable / not applicable (e.g., value) may include an indication of whether one or more links are acceptable (e.g., referring to whether one or more links are acceptable). The acceptability may be temporary and / or may be determined during at least one link evaluation period. Applicable / not applicable (e.g., value) may include (e.g., refer to) at least one link being IS / OOS, e.g., during at least one link evaluation period. The terms "message", "signal", and "sequence" may be used interchangeably herein.

[0094] The term "configured" may mean that the WTRU is pre-configured and / or the WTRU receives configuration from at least one of a node, the WTRU (e.g., another WTRU), and / or the network. The configuration may be sent via at least one of an SCI, a MAC CE, an RRC, a PC5-RRC, a Uu RRC, and / or an SIB. A positioning group may include multiple WTRUs. For example, one WTRU may be a target WTRU while at least one other WTRU may be an anchor WTRU. A forward link may be used to refer to the link / direction whose quality is measured by another WTRU, e.g., for unicast between two WTRUs. A reverse link may refer to the link / direction whose quality is measured by the (e.g., same) WTRU. A link may be used to refer to the WTRU associated with that link.

[0095] The WTRU may determine one or more positioning methods to use. The WTRU may determine the positioning method for one or more sidelink groups. For example, the WTRU may determine one or more positioning methods, including methods based on SL-PRS transmission, methods based on SL-PRS reception, methods based on RTT, SL-TDOA, SL-AoA, SL-AoD, methods based on Uu, methods based on SL, and / or methods that are a hybrid of Uu and SL. The WTRU may determine the positioning method for one or more groups based on one or more of the following: configuration; indication from a node, another WTRU, and / or one or more in the network; indication from a gNB; indication from a Location Management Function (LMF); and / or the QoS of the service.

[0096] The WTRU may determine which one of one or more WTRUs may perform link-based sidelink positioning monitoring. The WTRU may indicate (e.g., send an indication) to one or more WTRUs the decision as to which one of one or more WTRUs performs link-based sidelink positioning monitoring. For example, the WTRU may indicate information to one or more nodes, WTRUs, and / or networks regarding whether one or more nodes, WTRUs, and / or networks are to perform link-based sidelink monitoring. The WTRU may determine which WTRU is to perform link-based sidelink positioning monitoring based on one or more of the following: the target WTRU; the anchor WTRU; an indication from one or more nodes, WTRUs, and / or networks; one or more types of positioning indicators; one or more initiators of the positioning process, one or more positioning methods; one or more WTRUs that perform position calculation and receive one or more sidelink measurement results; one or more receivers of one or more sidelink measurement results; the output of the positioning process; and / or the type of WTRU. For example, the types of positioning indicators may include one or more of MO-LR, MT-LR, and / or NI-LR. The initiator of the positioning process may include one or more WTRUs that transmit a sidelink positioning request and / or one or more WTRUs that perform link-based sidelink positioning monitoring. Positioning may include one or more of the following: based on SL-PRS transmission, based on SL-PRS reception, based on RTT, SL-TDOA, SL-AoA, SL-AoD, based on Uu, based on SL, and / or based on a Uu and SL hybrid. The positioning server may include one or more of the following: the WTRU that calculates the position and / or the WTRU that receives one or more sidelink measurement results. The output of the positioning process may include one or more of the following: an indication as to whether the positioning output is an absolute position, a relative position, and / or a range.

[0097] A WTRU may determine whether to initiate a sidelink positioning monitoring procedure. For example, the WTRU may determine to initiate a sidelink positioning monitoring procedure. Additionally or alternatively, the WTRU may request one or more WTRUs to initiate a sidelink positioning monitoring procedure. The WTRU may make this determination based on an indication that one or more groups and / or link monitoring can be utilized (e.g., are required) for sidelink positioning. The WTRU may decide whether to initiate a sidelink positioning monitoring procedure, for example, based on one or more of the following: an indication from one or more of a node, the WTRU, and the network; whether the positioning procedure is session-based or non-session-based; the duration of a session-based procedure; the output of the positioning procedure; and / or the QoS requirements of the positioning service. For example, an indication from one or more of a node, the WTRU, and the network may include a request for one or more in a link and / or group to initiate sidelink positioning monitoring. Sidelink positioning monitoring can be utilized (e.g., is required) for a session-based positioning procedure. For example, for a non-session-based procedure, sidelink positioning monitoring may not be utilized (e.g., is not required). For example, if the session duration is greater than a threshold, sidelink positioning monitoring can be utilized (e.g., is required). If the session duration is not greater than the threshold, sidelink positioning monitoring may not be utilized (e.g., is not required). If the output of the positioning procedure is absolute, sidelink positioning monitoring can be utilized (e.g., is required). If the output of the positioning procedure is not absolute, sidelink positioning monitoring may not be utilized (e.g., is not required). For example, if the positioning availability requirement is higher than a threshold, WTRU sidelink positioning monitoring can be utilized (e.g., is required). For example, if the positioning availability requirement is not higher than the threshold, WTRU sidelink positioning monitoring may not be utilized (e.g., is not required).

[0098] The WTRU may determine the suitability of the link for sidelink positioning based on the received SL-PRS. In some embodiments, the WTRU may determine the suitability of the link for sidelink positioning based on the reliability of the SL-PRS. For example, if the WTRU does not detect one or more expected SL-PRS transmissions, the WTRU may determine that the link is not suitable. The one or more transmissions may be from a peer WTRU. The WTRU may determine the suitability of the link based on the quality of the SL-PRS, e.g., in the case where the WTRU detects one or more SL-PRSs from one or more peer WTRUs. For example, if one or more measurement parameters of the SL-PRS meet a threshold, the WTRU may determine that the link is suitable. For example, if the SL-RSRP is greater than the threshold, the WTRU may consider the link to be suitable. For example, if the SL-RSRP is less than the threshold, the WTRU may consider the link to be not suitable for sidelink positioning. If one or more line-of-sight / non-line-of-sight (LOS / NLOS) values are greater than the threshold, the WTRU may consider the link to be suitable. If one or more LOS / NLOS values are not greater than the threshold, the WTRU may consider the link to be not suitable. The SL-RSRP threshold and / or the LOS / NLOS threshold may be configured. The configuration may depend on one or more positioning methods / processes. The one or more positioning methods / processes may include one or more of the following: based on SL-PRS Tx, based on SL-PRS-Rx, based on RTT, AoA, and / or SL-TDOA. Alternatively or additionally, the one or more positioning methods / processes may include one or more QoS requirements of the positioning service. The number of expected SL-PRSs within an evaluation period may be configured.

[0099] A WTRU may determine the suitability of a link for positioning based on one or more received sidelink transmissions. For example, the WTRU may receive one or more sidelink transmissions from one or more peer WTRUs. The sidelink transmission may be one or more of a data transmission and / or a discovery transmission. The WTRU may determine the suitability of the link for sidelink positioning based on the availability of an expected sidelink transmission. For example, if the WTRU does not detect one or more expected sidelink transmissions from one or more peer WTRUs, the WTRU may determine that the link is not suitable. For example, if the WTRU detects one or more sidelink transmissions from one or more peer WTRUs, the WTRU may determine the suitability of the link based on the quality of the sidelink reception. For example, if one or more measurement parameters of the sidelink transmission meet a threshold, the WTRU may determine that the link is suitable. If one or more RSRPs measured in sidelink discovery reception (SD-RSRP) and / or sidelink data reception (SL-RSRP) are greater than the threshold, the WTRU may consider (e.g., determine) that the link is suitable. The WTRU may (e.g., otherwise) consider that the link is not suitable for sidelink positioning. The threshold may be configured.

[0100] In some embodiments, the WTRU may report one or more sidelink measurement results to one or more peer WTRUs. For example, the WTRU may receive sidelink transmissions from one or more peer WTRUs. The sidelink transmission may be one or more of a data transmission and / or a discovery transmission. The WTRU may (e.g., then) perform measurements in one or more (e.g., different) types of transmissions from the one or more peer WTRUs. For example, the WTRU may (e.g., then) report one or more measurement parameters to another node (e.g., the Tx WTRU). The measurement parameters may include one or more of the following: SL-RSRP measured on the relevant PSCCH / PSSCH of the SL-PRS, measured SL-RSRP of the SL-PRS, SL-RSRP measured in a sidelink transmission, SD-RSRP measured in a discovery transmission, LOS / NLOS value, ToA, Tx-Rx, AoA, and / or AoD.

[0101] A WTRU may determine the applicability of one or more links for sidelink positioning based on one or more measurement reports. For example, the WTRU may receive one or more sidelink measurement reports from one or more peer WTRUs. The WTRU may (e.g., then) determine the applicability of the link for sidelink positioning, e.g., based on the availability of expected sidelink measurement reports from one or more peer WTRUs. For example, if the WTRU does not detect one or more expected sidelink measurement reports (e.g., N) from a peer WTRU, the WTRU may consider the link inapplicable. For example, if the WTRU detects one or more expected sidelink measurement reports, the WTRU may determine the applicability of the link for sidelink positioning based on the measured values of the parameters indicated in the sidelink measurement report. For example, if the values indicated in the sidelink measurement report are within a configured range and / or a predetermined range, the WTRU may consider the link applicable.

[0102] The configured and / or predetermined range may include one or more thresholds. For example, if the configured and / or predetermined range includes a threshold, the WTRU may assume one or more of the one or more thresholds (e.g., other thresholds) to be infinite or zero. The configured and / or predetermined range may be based on (e.g., depend on) one or more positioning methods (e.g., SL-PRS Tx-based, SL-PRS-Rx-based, RTT-based, AoA, SL-TDOA, etc.). Additionally or alternatively, the configured and / or predetermined range may be based on (e.g., depend on) one or more QoS requirements of the positioning service. The number of expected SL-PRSs (e.g., N) within an evaluation period may be configured. For example, the WTRU may receive measurement reports for transmitted SL-PRSs from one or more peer WTRUs.

[0103] The WTRU may receive SL-RSRP, e.g., measured in an SL-PRS. For example, if the reported SL-RSRP is greater than one or more thresholds, the WTRU may consider the link applicable for sidelink positioning. For example, if the SL-RSRP is less than one or more thresholds, the WTRU may consider the link inapplicable for sidelink positioning. The WTRU may receive one or more LOS / NLOS values, e.g., measured in an SL-PRS. For example, if the reported SL-RSRP is greater than one or more thresholds, the WTRU may consider the link applicable for sidelink positioning. For example, if the SL-RSRP is less than the one or more thresholds, the WTRU may consider the link inapplicable for sidelink positioning.

[0104] A WTRU can evaluate one or more links by using one or more link quality metrics. The link quality metrics can be used to evaluate the quality of sidelink positioning (e.g., based on SL-RSRP, LOS / NLOS related to the forward / reverse link). For example, the link quality metrics can include one or more of the following: the received SL-PRS signal quality measured by the WTRU, the SL-PRS signal quality reported by a peer WTRU, the discovery signal quality reported by a peer WTRU, the sidelink data quality reported by a peer WTRU, the sidelink data signal quality measured by the WTRU, the sidelink feedback signal quality of sidelink data (e.g., PSFCH) measured by the WTRU, the sidelink feedback signal quality of SL-PRS transmission measured by the WTRU, and the sidelink discovery signal quality measured by the WTRU. The WTRU can determine the link quality metrics based on one or more of SL-PRS transmission and / or SL-PRS measurement reports reception. The WTRU can determine one or more link quality metrics based on SL-PRS reception. For example, the WTRU can determine one or more link quality metrics based on the SL-PRS signal quality reported by one or more peer WTRUs. The WTRU can determine the link quality metrics based on one or more of SL-PRS reception and / or the SL-PRS signal quality reported by one or more peer WTRUs.

[0105] The WTRU can determine which one of the one or more link quality metrics to use for link-based sidelink position monitoring. The WTRU can determine which one of the one or more link quality metrics to use for link-based sidelink positioning monitoring (e.g., determine the suitability of the link for sidelink positioning) based on one or more of the positioning methods / procedures described herein. The WTRU can use the received SL-PRS signal quality as a link quality metric, e.g., for methods / procedures based on SL-PRS reception. For example, the WTRU can determine the suitability of the link for sidelink positioning based on the received SL-PRS.

[0106] The WTRU can use the SL-PRS measurement report as a link quality metric, e.g., for methods / procedures based on SL-PRS transmission. For example, the WTRU can determine the suitability of the link for sidelink positioning based on the SL-PRS measurement reports from one or more peer WTRUs.

[0107] The WTRU can use both SL-PRS reception and the SL-PRS measurement report as link quality metrics, e.g., for methods / procedures based on RTT. For example, the WTRU can determine the suitability of the link for sidelink positioning based on SL-PRS reception and the SL-PRS measurement reports from peer WTRUs.

[0108] Additionally or alternatively, the WTRU may determine which one of one or more link quality metrics to use for link-based sidelink positioning monitoring (e.g., determine the suitability of the link for sidelink positioning). The WTRU may determine which one of one or more link quality metrics to use for link-based sidelink positioning monitoring based on the priority of one or more different types of sidelink reception that have been configured. For example, the WTRU may prefer to use SL-PRS reception (e.g., if it is available). For example, if SL-PRS reception is not available, the WTRU may prefer to use an SL-PRS measurement report. The WTRU may (e.g., otherwise) prefer to use data reception.

[0109] The WTRU may determine which one of one or more link quality metrics to use for link-based sidelink positioning monitoring based on one or more of the availability and / or frequency of (e.g., different) types of sidelink reception (e.g., SL-PRS, sidelink data, feedback of SL-PRS, feedback of sidelink data, and / or discovery reception). For example, if the WTRU periodically receives SL-PRS, the WTRU may prefer to use SL-PRS reception to determine the availability of the link for sidelink positioning. For example, if the WTRU periodically receives an SL-PRS measurement report, the WTRU may prefer to use the SL-PRS measurement report to determine the availability of the link for sidelink positioning.

[0110] The WTRU may use a set of sidelink receptions (e.g., SL-PRS, sidelink data, and sidelink discovery reception) as a link quality metric, e.g., for determining the suitability of the link for sidelink positioning. For example, the WTRU may use the filtered RSRP in a set of sidelink receptions (e.g., SL-PRS, sidelink data, and sidelink discovery) from one or more peer WTRUs to determine the suitability of one or more links for sidelink positioning. For example, if the filtered RSRP is less than one or more thresholds, the WTRU may consider the link unsuitable. For example, if the filtered RSRP is greater than one or more thresholds, the WTRU may consider the link suitable.

[0111] The WTRU may determine when to evaluate the suitability of one or more links for sidelink positioning. The WTRU may determine when to periodically evaluate the suitability of a link for sidelink positioning. For example, the WTRU may be configured to evaluate the suitability of a link for sidelink positioning. The WTRU may (e.g., then) periodically evaluate the suitability of the link for sidelink positioning. The periodicity of the evaluation may be based on the periodicity of SL-PRS reception and / or SL-PRS measurement reports.

[0112] The WTRU may determine when to evaluate the suitability of a link for sidelink positioning, e.g., based on the reception and / or expected reception time of the SL-PRS. The WTRU may evaluate the suitability of a link for sidelink positioning based on the time of reception or expected time of the SL-PRS reception, e.g., for methods based on SL-PRS Rx.

[0113] The WTRU may determine when to evaluate the suitability of a link for sidelink positioning based on the reception and / or expected reception time of SL-PRS measurement reports from one or more peer WTRUs. The WTRU may evaluate the suitability of the link for sidelink positioning based on the reception and / or expected reception timing of SL-PRS measurement reports from one or more peer WTRUs, e.g., for RTT-based positioning methods and / or for positioning methods based on SL-PRS transmissions.

[0114] The WTRU may determine when to evaluate the suitability of a link for sidelink positioning based on the reception and / or expected reception time of discovery signal quality reported by a peer WTRU. The WTRU may determine when to evaluate the suitability of a link for sidelink positioning based on the expected reception time of sidelink data quality reported by one or more peer WTRUs. The WTRU may determine when to evaluate the suitability of a link for sidelink positioning based on the expected reception time of sidelink data transmissions performed by one or more peer WTRUs. The WTRU may determine when to evaluate the suitability of a link for sidelink positioning based on the expected reception time of sidelink discovery transmissions performed by one or more peer WTRUs. The WTRU may determine when to evaluate the suitability of a link for sidelink positioning based on the expected reception time of sidelink feedback for sidelink data (e.g., PSFCH). The WTRU may determine when to evaluate the suitability of a link for sidelink positioning based on the expected reception time of sidelink feedback for SL-PRS transmissions.

[0115] The WTRU may trigger a sidelink transmission for sidelink positioning monitoring. The WTRU may request one or more peer WTRUs to perform sidelink transmissions (e.g., SL-PRS, sidelink data, discovery, WTRU status report), e.g., to support sidelink positioning monitoring. The WTRU may request a report of status to support sidelink positioning monitoring.

[0116] A WTRU may determine one or more of sidelink data and / or sidelink discovery transmissions. The WTRU may transmit a WTRU status report. The status report may include a coverage status, such as including whether the WTRU is within network coverage or outside network coverage. The WTRU status report may include a resource allocation mode of the WTRU. The status report may include the Uu condition of the WTRU. The status report may include an RRC status. The RRC status may include whether the WTRU is in RRC_CONNECTED and / or idle / inactive. The status may include a synchronization status (e.g., quality of the synchronization source, priority of the synchronization source, etc.). The status report may include positioning information of the WTRU. The positioning information may include one or more of the following: a positioning indication of the WTRU, an error bound of the positioning location, an integrity of the WTRU location, a movement (e.g., speed) of the WTRU, etc. The WTRU may transmit a message (e.g., a keep-alive message), such as to periodically check the suitability of the link. The status report may include SL-PRS transmissions.

[0117] One or more transmissions for supporting sidelink positioning monitoring may be based on configured periodic transmissions. The WTRU may (e.g., periodically) request one or more peer WTRUs to perform sidelink transmissions. For example, the WTRU may (e.g., periodically) request the one or more peer WTRUs to report status. The WTRU may (e.g., periodically) perform sidelink transmissions (e.g., SL-PRS, discovery, and / or sidelink data transmissions), such as for supporting sidelink positioning monitoring. The number of sidelink transmissions / receptions within an evaluation period may be less than one or more configured thresholds. The number of sidelink transmissions / receptions within an evaluation period may be greater than or equal to one or more configured thresholds.

[0118] The WTRU may determine the link to be unsuitable within one or more of a configured duration and / or a configured number of evaluation events. For example, if the WTRU determines the link to be unsuitable, the WTRU may trigger the transmission of SL-PRS. The WTRU may (e.g., expect) to receive SL-PRS measurement reports from one or more peer WTRUs. The WTRU may (e.g., further) evaluate the link for sidelink positioning. The WTRU may not receive a configured minimum number of transmissions (e.g., SL-PRS transmissions) for evaluating the suitability of the link within a configured duration.

[0119] A WTRU may determine whether to form one or more positioning groups. For example, the WTRU may perform one or more of the following: form and / or create one or more positioning groups. The WTRU may determine to establish group connections for sidelink positioning. The WTRU may receive (e.g., from the network) and / or create group-specific IDs (e.g., destination IDs) for communication between one or more WTRUs in a positioning group. The WTRU may determine whether to perform one or more of the following based on one or more indications from another node: form and / or create one or more positioning groups. For example, the WTRU may receive an indication from a gNB (e.g., the LMF) to form one or more positioning groups. The WTRU may determine whether to perform one or more of the following based on one or more positioning methods / processes: form and / or create one or more positioning groups. The WTRU may form one or more positioning groups, e.g., for SL-TDOA. The WTRU may (otherwise) not form a positioning group, e.g., for m-RTT. The WTRU may determine whether to perform one or more of the following based on the (e.g., expected) positioning result of a positioning method / process: form and / or create one or more positioning groups. For example, if the positioning result is absolute, the WTRU may form a sidelink positioning group (e.g., consisting of one or more WTRUs). The WTRU may (otherwise) not form a positioning group, e.g., if the positioning result is relative or one or more of a range.

[0120] A WTRU may determine which WTRU (e.g., which may include the WTRU itself) will perform group-based sidelink positioning monitoring. The WTRU may (e.g., then) indicate a decision to one or more different WTRUs. For example, the WTRU may indicate to one or more other nodes (e.g., other WTRUs or gNBs) whether the WTRU and / or another WTRU (e.g., the WTRU may include the WTRU ID) may perform group-based sidelink positioning monitoring. The WTRU may determine which WTRU (which may include the WTRU itself) will perform group-based sidelink positioning monitoring based on the target WTRU. For example, if the WTRU forms a set of anchor WTRUs to determine location, the target WTRU may perform group-based sidelink positioning monitoring. The WTRU may determine which WTRU (which may include the WTRU itself) performs group-based sidelink positioning monitoring based on one or more anchor WTRUs. For example, if the WTRU initiates a positioning group (e.g., for NI-LR or MT-LR) to support one or more target WTRUs, the one or more anchor WTRUs may perform group-based sidelink positioning monitoring. The WTRU may determine which WTRU (which may include the WTRU itself) performs group-based sidelink positioning monitoring based on an indication from one or more other nodes (e.g., one or more other WTRUs or gNBs). For example, the WTRU may receive an indication (e.g., be instructed) from one or more other nodes (e.g., a gNB) to perform group-based sidelink positioning monitoring.

[0121] The WTRU may (e.g., then) determine whether to perform the monitoring and / or may (e.g., then) send feedback of such a decision to one or more requesting nodes (e.g., gNB) (e.g., the WTRU may give feedback to one or more requesting nodes as to whether the one or more nodes perform sidelink positioning monitoring). The WTRU may determine which WTRU (which may include the WTRU itself) will perform group-based sidelink position monitoring based on the type of the positioning initiator (e.g., whether the positioning initiator is MO-LR, MT-LR, NI-LR). The target WTRU may perform group-based sidelink positioning monitoring, e.g., for MO-LR. One or more anchor WTRUs may perform group-based sidelink positioning monitoring, e.g., for MT-LR. The WTRU may determine which WTRU (which may include the WTRU itself) will perform group-based sidelink position monitoring based on the initiator of the positioning procedure. For example, if the WTRU transmits a sidelink positioning request, the WTRU may perform group-based sidelink positioning monitoring. For example, if the WTRU transmits a discovery for sidelink positioning, the WTRU may perform group-based sidelink positioning monitoring. The WTRU may determine which WTRU (which may include the WTRU itself) will perform group-based sidelink position monitoring based on the positioning method / process (e.g., based on SL-PRS transmission, based on SL-PRS reception, based on RTT, SL-TDOA, SL-AoA, SL-AoD, and / or based on Uu and SL hybrid). One or more WTRUs may each perform group-based sidelink positioning monitoring, e.g., for an RTT-based method.

[0122] Additionally or alternatively, the recipient WTRU of the measurement report may perform group-based sidelink positioning monitoring. The target WTRU may perform group-based sidelink positioning monitoring, such as for SL-TDOA. One or more anchor WTRUs may perform group-based sidelink positioning monitoring, such as for methods based on SL-PRS transmissions. The WTRU may determine which WTRU (which may include the WTRU itself) will perform group-based sidelink position monitoring based on the positioning server WTRU (e.g., the WTRU that calculates one or more positions and receives one or more sidelink measurement reports). The WTRU may determine which WTRU (which may include the WTRU itself) will perform group-based sidelink position monitoring based on the recipient of the sidelink measurement report. The WTRU may determine which WTRU (which may include the WTRU itself) will perform group-based sidelink position monitoring based on the output of the positioning process (e.g., whether the output of the positioning is an absolute position, a relative position, and / or a range). One or more WTRUs may perform group-based sidelink positioning monitoring, such as for relative positioning. The target WTRU may perform group-based sidelink positioning monitoring, such as for absolute positioning. The WTRU may determine which WTRU (which may include the WTRU itself) will perform group-based sidelink position monitoring based on the type of WTRU. For example, an RSU may perform link-based sidelink monitoring.

[0123] A WTRU may determine whether to monitor one or more of the WTRUs and / or links in a group. The WTRU may determine whether to monitor one or more of the WTRUs and / or links in a group, for example, based on the positioning accuracy of the WTRU. For example, if the positioning accuracy of the WTRU is greater than one or more configured thresholds, the WTRU may monitor the WTRU (e.g., the WTRU in the group). The WTRU may (e.g., otherwise) not monitor the WTRU. The WTRU may determine whether to monitor one or more of the WTRUs and / or links in a group based on the synchronization accuracy of the WTRU. For example, if the positioning accuracy and / or the synchronization priority of the WTRU is greater than one or more configured thresholds, the WTRU may monitor the WTRU (e.g., the WTRU in the group). For example, if the WTRU uses the same synchronization source, the WTRU may monitor the WTRU (e.g., the WTRU in the group). For example, the WTRU may (e.g., otherwise) not monitor the WTRU (e.g., the WTRU in the group). The WTRU may determine whether to monitor one or more of the WTRUs and / or links in a group based on the relative distance to the WTRU. For example, if the relative distance to the WTRU is within a configured and / or predetermined range, the WTRU may monitor the WTRU (e.g., the WTRU in the group). For example, the WTRU may (e.g., otherwise) not monitor the WTRU (e.g., the WTRU in the group). The WTRU may determine whether to monitor one or more of the WTRUs and / or links in a group based on the link quality between one or more WTRUs. For example, if one or more of the SL-RSRP and / or LOS / NLOS of the link to the WTRU is greater than one or more configured thresholds, the WTRU may monitor the WTRU (e.g., the WTRU in the group). For example, the WTRU may (e.g., otherwise) not monitor the WTRU (e.g., the WTRU in the group).

[0124] The WTRU may determine a set consisting of one or more of the links and / or WTRUs to be monitored in the group. For example, the WTRU may be configured to monitor a minimum number of links (e.g., N) for sidelink positioning monitoring based on the group. The WTRU may (e.g., then) determine to monitor at least N links. The set consisting of one or more of the links and / or WTRUs to be monitored may (e.g., then) be determined based on other factors. The other factors may include one or more of the following: the positioning accuracy, synchronization accuracy, distance, link quality, etc. of one or more WTRUs in the group.

[0125] The WTRU may determine whether a positioning group belongs to one or more of the following: applicable to and / or not applicable to sidelink positioning. For example, during an evaluation period, the WTRU may determine whether a positioning group belongs to one or more of the following: applicable to and / or not applicable to (e.g., group applicable / group not applicable) sidelink positioning. The WTRU may determine whether the positioning group is applicable based on the number of one or more of the applicable links and / or applicable WTRUs in the group during the evaluation period. For example, the WTRU may be configured with a minimum number (e.g., N) of one or more of the applicable links and applicable WTRUs to determine whether the positioning group belongs to one or more of: applicable and / or not applicable. If there are at least N applicable links and / or WTRUs in the positioning group, the WTRU may determine the positioning group as applicable (e.g., group applicable). The WTRU may (e.g., otherwise) determine the positioning group as not applicable (e.g., group not applicable), for example if the number of one or more of the applicable links and applicable WTRUs present is less than N.

[0126] The WTRU may determine when to evaluate the applicability of a positioning group for sidelink positioning. For example, the WTRU may determine when to evaluate the applicability of a positioning group for sidelink positioning based on periodicity. The WTRU may be configured to evaluate the applicability of a positioning group for sidelink positioning. The WTRU may (e.g., then) periodically evaluate the applicability of the link for sidelink positioning. For example, the periodicity of the evaluation may be based on the periodicity of one or more of the SL-PRS reception and / or SL-PRS measurement reports.

[0127] The WTRU may determine when to evaluate the applicability of a positioning group for sidelink positioning based on the reception and / or expected reception time of a configured minimum number of SL-PRSs from the group. For example, for a SL-PRS Rx-based method, the WTRU may evaluate the applicability of the group for sidelink positioning based on the time and / or expected reception time of a configured minimum number of SL-PRSs from a group. The WTRU may determine when to evaluate the applicability of a positioning group for sidelink positioning based on one or more of: the reception and / or expected reception time of a configured minimum number of SL-PRS measurement reports provided by the member WTRUs.

[0128] The WTRU can evaluate the applicability of the group for sidelink positioning based on the reception or expected reception timing of a configured minimum number of SL-PRS measurement reports from the member WTRUs, e.g., for RTT-based positioning methods and / or for methods / processes based on SL-PRS transmission. The WTRU can determine when to evaluate the applicability of the positioning group for sidelink positioning based on one or more of the following: the reception and / or expected reception time of a configured minimum number of discovery signal qualities reported by the WTRUs in the group. The WTRU can determine when to evaluate the applicability of the positioning group for sidelink positioning based on one or more of the following: the reception and / or expected reception time of a configured minimum number of sidelink data qualities reported by the member WTRUs.

[0129] The WTRU can determine when to evaluate the applicability of the positioning group for sidelink positioning based on one or more of the following: the reception and / or expected reception time of a configured minimum number of sidelink data transmissions provided by the member WTRUs. The WTRU can determine when to evaluate the applicability of the positioning group for sidelink positioning based on one or more of the following: the reception and / or expected reception time of a configured minimum number of sidelink discovery transmissions provided by the member WTRUs. The WTRU can determine when to evaluate the applicability of the positioning group for sidelink positioning based on one or more of the following: the reception and / or expected reception time of a configured minimum number of sidelink feedbacks for sidelink data (e.g., PSFCH) from the member WTRUs. The WTRU can determine when to evaluate the applicability of the positioning group for sidelink positioning based on one or more of the following: the reception and / or expected reception time of a configured minimum number of sidelink feedbacks for SL-PRS transmission from the member WTRUs.

[0130] A WTRU can determine whether another WTRU is moving out of the group, for example, based on the sidelink condition between the other WTRU and the WTRU. The sidelink condition between WTRUs can be determined based on the distance and / or direction between the WTRUs. For example, if the distance between the WTRUs is greater than (e.g., configured and / or predefined) threshold, the WTRU can determine that another WTRU is moving out of the group. The WTRU can (e.g., otherwise) determine that the other WTRU is still in the group. The sidelink condition between two WTRUs can be determined based on the channel condition between the WTRUs. The sidelink condition between WTRUs can be determined based on the measurement results of one or more transmissions between the WTRUs. The measurement results can include one or more of SL-RSRP, SL-RSSI, and / or LOS / NLOS measurement results. The transmissions between WTRUs can include one or more of SL-PRS transmissions, sidelink data transmissions, and / or sidelink control transmissions. For example, if the measured SL-RSRP of the (one or more) transmissions between the WTRUs is less than (e.g., configured and / or predefined) threshold, the WTRU can determine that another WTRU is moving out of the group. If the measured SL-RSRP of the transmissions between the WTRUs is greater than (e.g., configured and / or predefined) threshold, the WTRU can determine that the other WTRU is still in the group.

[0131] A WTRU can determine whether to maintain or terminate a sidelink positioning group and / or a sidelink positioning session, for example, based on one or more WTRUs moving out of the group. For example, if the number of WTRUs moving out of the group is less than (e.g., configured and / or predefined) threshold, the WTRU can determine to maintain the group and / or the sidelink positioning session. The WTRU can (e.g., otherwise) determine to terminate the group and / or the sidelink positioning session, for example, if the number of WTRUs moving out of the group is greater than (e.g., configured and / or predefined) threshold. Additionally or alternatively, if the number of remaining WTRUs in the group is greater than (e.g., configured and / or predefined) threshold, the WTRU can determine to maintain the group and / or the sidelink positioning session. Additionally or alternatively, if the number of remaining WTRUs in the group is less than the configured threshold, the WTRU can (e.g., otherwise) determine to terminate the group and / or the sidelink positioning session. The WTRU can send an indication to another node, for example, when one or more WTRUs are moving out / have moved out of the group. The other node can include, for example, one or more of the following: gNB, LMF, and / or one or more other WTRUs (e.g., anchor WTRUs). The WTRU can send an indication to the other node to terminate the positioning group and / or the sidelink positioning session. Additionally or alternatively, the WTRU can send an indication to the other node to maintain the positioning group and / or the sidelink positioning session.

[0132] The WTRU may send an indication to one or more other nodes to terminate a positioning group and / or a positioning session. For example, the WTRU may send an indication to the network (such as the LMF) to terminate a positioning group and / or a sidelink positioning session. The WTRU may send a request for terminating a positioning group and / or a positioning session. Additionally or alternatively, the WTRU may send an indication to one or more other WTRUs (such as one or more anchor WTRUs) to terminate a positioning group and / or a positioning session.

[0133] The WTRU may send an indication to one or more other nodes to maintain a positioning group and / or a positioning session. For example, the WTRU may send an indication to the network (such as the LMF) to update the set of WTRUs in the group. The WTRU may request a new SL-PRS transmission configuration for the group. Additionally or alternatively, the WTRU may send an indication to one or more other WTRUs to maintain a positioning group and / or a sidelink positioning session. The WTRU may send an update of the positioning group, for example, the update includes a set of (e.g., new) WTRUs for the group and / or SL-PRS transmission resources.

[0134] The WTRU may declare that a link is continuously unavailable for sidelink positioning (LPUSP). Additionally or alternatively, the WTRU may trigger an LPUSP timer. The WTRU may evaluate one or more links to determine the suitability of the one or more links for sidelink positioning. For example, the WTRU may perform this evaluation while and / or after triggering the LPSUP timer. For example, if the number of one or more suitability indications is less than one or more thresholds, the WTRU may declare one or more links as LPUSP. For example, the WTRU may declare the link as LPSUP when the LPUSP timer expires.

[0135] The WTRU may declare that a group is continuously unavailable for sidelink positioning (GPUSP). Additionally or alternatively, the WTRU may trigger a GPUSP timer. In some embodiments, the WTRU may evaluate one or more links to determine the suitability of the one or more links for sidelink positioning. For example, the WTRU may perform this evaluation while and / or after triggering the GPSUP timer. For example, if the number of one or more suitability indications is less than one or more thresholds, the WTRU may declare one or more links as GPUSP. For example, the WTRU may declare the link as GPSUP when the GPUSP timer expires.

[0136] The WTRU may determine whether to declare one or more of LPSUP and / or GPSUP. For example, the WTRU may determine whether to declare one or more of LPSUP and / or GPSUP based on whether the WTRU determines that one or more of the links and / or groups are not applicable within one or more of a configured duration, number of evaluation periods, and / or number of indications. The WTRU may determine whether to declare one or more of LPSUP and / or GPSUP based on receiving one or more of LPUSP and / or GPUSP from one or more other nodes (e.g., from one or more other WTRUs and / or gNBs).

[0137] The WTRU may perform one or more of the methods / procedures described herein while and / or after determining that one or more of the links and groups are not applicable for sidelink positioning. Additionally or alternatively, the WTRU may perform one or more of the following while and / or after declaring LPUSP and / or GPUSP. The WTRU may send an indication (e.g., one or more of LPUSP, GPUSP, and link / group applicability indication) to one or more other nodes (e.g., the network or a peer WTRU). The WTRU may request one or more other WTRUs to stop sidelink transmissions for sidelink positioning monitoring (e.g., SL-PRS, sidelink data, sidelink discovery, sidelink feedback, etc.). The WTRU may release a link. The WTRU may stop one or more sidelink positioning sessions. The WTRU may remove one or more links from one or more sidelink positioning groups. The WTRU may release one or more groups. The WTRU may stop one or more sidelink positioning sessions. The WTRU may perform one or more positioning request transmissions. The WTRU may add one or more WTRUs to a group. The WTRU may trigger one or more positioning request transmissions to request support from more WTRUs. The WTRU may change one or more positioning methods / procedures. The WTRU may change from one positioning method / procedure to another, e.g., if the WTRU declares GPUSP for a positioning group.

[0138] A WTRU may receive one or more indications for sidelink positioning monitoring from one or more other nodes. The WTRU may receive one or more of LPUSP and / or GPUSP. The WTRU may receive information that the WTRU is releasing a link. The WTRU may receive information that one or more WTRUs may leave a sidelink positioning group. The WTRU may receive information that a WTRU changes from within coverage to outside coverage. The WTRU may receive one or more pieces of information that a WTRU changes from outside coverage to within coverage. The WTRU may receive information that one or more WTRUs change a resource allocation mode for sidelink positioning. The WTRU may receive information that one or more WTRUs may experience Uu RLF. The WTRU may receive information that one or more WTRUs change an RRC state. The WTRU may receive information that one or more WTRUs hand over to another cell.

[0139] Additionally or alternatively, the WTRU may, for example, suspend a positioning process / session after receiving one or more indications. For example, the WTRU may indicate to one or more other WTRUs to suspend one or more positioning processes / sessions. Additionally or alternatively, the WTRU may suspend transmitting one or more of SL-PRS and / or measurement reports. The WTRU may, for example, stop a positioning session after receiving one or more indications. The WTRU may, for example, release one or more links after receiving one or more indications. The WTRU may, for example, release one or more positioning groups after receiving one or more indications. The WTRU may, for example, change one or more resource allocation modes (e.g., change from mode 1 to mode 2) after receiving one or more indications. The WTRU may, for example, change one or more positioning methods after receiving one or more indications. The WTRU may, for example, release one or more links and trigger one or more sidelink positioning discovery processes after receiving one or more indications. The one or more sidelink positioning discovery processes may find one or more anchor WTRUs.

[0140] The WTRU may establish a group for sidelink positioning. The WTRU may establish one or more group connections. For example, the one or more group connections may be for a group of WTRUs. Additionally or alternatively, the one or more group connections may support sidelink positioning. The WTRU may be assigned (e.g., by the LMF) to communicate with one or more WTRUs in the group. Alternatively or additionally, the WTRU may use a group ID (e.g., a destination ID) to communicate with one or more WTRUs in the group.

[0141] A WTRU may select one or more WTRUs for one or more positioning sessions. The WTRU may initiate a positioning session. For example, the WTRU may (e.g., then) select a set of one or more WTRUs in a positioning group to support WTRU positioning. The WTRU may transmit one or more positioning request messages, e.g., to request support from one or more anchor WTRUs. The one or more positioning request messages may include one or more group IDs, e.g., from one or more previously established groups. The WTRU selects one or more anchor WTRUs from a set of one or more trusted WTRUs using, e.g., one or more of the methods / procedures described herein. Additionally or alternatively, the WTRU may (e.g., then) release the WTRU (e.g., by sending a release message) at the end of the positioning session.

[0142] The WTRU may perform link-based sidelink positioning monitoring. Figure 3FIG. illustrates a flow chart of an example process 300 for link-based sidelink positioning monitoring. At 302, the WTRU may be configured and / or pre-configured with one or more parameters for link monitoring. One or more parameters for link monitoring may include a threshold for an applicable / inapplicable indication (e.g., LOS / NLOS threshold), an applicable / inapplicable evaluation period, and / or a number of inapplicable indications (e.g., consecutive inapplicable indications) for declaring an LPUSP. At 304, the WTRU may establish a connection with one or more other WTRUs (e.g., an anchor WTRU) for sidelink positioning. For example, at 306, the WTRU may receive an indication from the network as to which type of positioning method to use. The indication may include one or more of the following: SL-PRS Rx-based, SL-PRS Tx-based, and / or RTT-based. The WTRU may receive an indication to use an RTT-based method at 308. The WTRU may receive an indication to use an SL-PRS Rx-based method at 310. The WTRU may receive an indication to use an SL-PRS Tx-based method at 312. The WTRU may determine which one or more link quality metrics to use to evaluate the link for link-based sidelink positioning monitoring based on the positioning method / process. The WTRU may utilize one or more of SL-PRS reception and / or SL-PRS measurement reports from one or more peer WTRUs as link quality metrics, e.g., for RTT-based. At 314, the WTRU may perform one or more of the following: transmit SL-PRS, receive SL-PRS, and / or receive an SL-PRS measurement report from a peer WTRU, e.g., within one or more applicable / inapplicable evaluation periods. At 316, the WTRU may receive SL-PRS from a peer WTRU, e.g., within one or more applicable / inapplicable evaluation periods. At 318, the WTRU may perform one or more of the following: transmit SL-PRS, receive SL-PRS, and / or receive an SL-PRS measurement report from a peer WTRU, e.g., within one or more applicable / inapplicable evaluation periods. The WTRU may (e.g., then) determine / consider the link to be applicable, e.g., if one or more of the received signal quality of the SL-PRS and / or the reported SL-PRS measurement results meet one or more thresholds (e.g., LOS / NLOS > threshold related to both the received SL-PRS and / or the transmitted SL-PRS). The WTRU may (e.g., otherwise) consider one or more links to be inapplicable.

[0143] A WTRU can use SL-PRS reception as a link quality metric to evaluate a link, e.g., for SL-PRS Rx-based. The WTRU can (e.g., first) receive SL-PRS from a peer WTRU, e.g., within each of one or more applicable / inapplicable evaluation periods. The WTRU can (e.g., then) consider the one or more links as applicable, e.g., if the received SL-PRS meets one or more thresholds (e.g., LOS / NLOS associated with the received SL-PRS > threshold). For example, the WTRU can (e.g., otherwise) consider the one or more links as inapplicable. The WTRU can use SL-PRS measurement report reception as one or more quality metrics, e.g., for SL-PRS Tx-based. The WTRU can (e.g., first) transmit SL-PRS and / or receive SL-PRS measurement reports from one or more peer WTRUs, e.g., within each of one or more applicable / inapplicable periods. At 320, the WTRU can determine whether the LOS / NLOS associated with the received SL-PRS and / or the transmitted SL-PRS exceeds a threshold. At 322, the WTRU can determine whether the LOS / NLOS associated with the received SL-PRS exceeds a threshold. At 324, the WTRU can determine whether the LOS / NLOS indicated in the SL-PRS measurement report exceeds a threshold. For example, if one or more reported SL-PRS measurement results meet one or more thresholds (e.g., LOS / NLOS indicated in the SL-PRS measurement report > threshold), the WTRU can consider the link as applicable. At 326, the WTRU can increment the number of consecutive indications (e.g., a counter). The WTRU can (e.g., otherwise) consider the one or more links as inapplicable. The WTRU can use one or more links to determine / deduce one or more locations, e.g., if the number of inapplicable indications (e.g., consecutive inapplicable indications) is less than one or more thresholds. For example, if at 328, the number of inapplicable indications (e.g., consecutive inapplicable indications) is greater than or equal to one or more thresholds, the WTRU can, at 330, perform one or more of the following: send an LPUSP indication to one or more nodes (e.g., the network or a peer WTRU), release one or more links, and / or stop one or more sidelink positioning sessions.

[0144] The WTRU can perform link-based sidelink positioning monitoring. Figure 4The flowchart illustrates an example process 400 for group-based sidelink positioning monitoring. At 402, the WTRU may be configured and / or pre-configured with one or more parameters for group-based sidelink positioning monitoring. The one or more parameters for group-based sidelink positioning monitoring may include one or more of the following: the minimum number of applicable links (i.e., N) for determining the group applicability, one or more thresholds for determining link applicability / inapplicability, one or more group applicability / group inapplicability evaluation periods, and / or one or more numbers (e.g., consecutive) of group inapplicability indications for declaring the group as GPUSP. At 404, the WTRU may establish one or more sidelink positioning groups. The sidelink positioning group may include M member WTRUs (e.g., an anchor WTRU). At 406, the WTRU may receive an indication from one or more networks as to which type of positioning method to use (e.g., SL-PRS Rx-based, SL-PRS Tx-based, and / or m-RTT-based). The WTRU may (e.g., first) transmit SL-PRS to one or more member WTRUs, e.g., for RTT-based and / or within each of one or more cycles. The WTRU may (e.g., then) receive SL-PRS and / or SL-PRS measurement reports from each of one or more member WTRUs in one or more of the groups. At 414, the WTRU may perform one or more of the following: transmit SL-PRS, receive SL-PRS, and / or receive SL-PRS measurement reports from (one or more) member WTRUs, e.g., within one or more group applicability / inapplicability evaluation periods. At 416, the WTRU may receive SL-PRS from (one or more) member WTRUs, e.g., within one or more group applicability / inapplicability evaluation periods. At 418, the WTRU may perform one or more of the following: transmit SL-PRS, receive SL-PRS, and / or receive SL-PRS measurement reports from (one or more) member WTRUs, e.g., within one or more group applicability / inapplicability evaluation periods. The WTRU may (e.g., then) determine (e.g., consider) one or more positioning groups to be group applicable, e.g., if one or more of the quality of the SL-PRS received from at least N WTRUs and / or the values of the reported SL-PRS measurement results meet one or more thresholds (e.g., LOS / NLOS > threshold). The WTRU may (e.g., otherwise) determine (e.g., consider) the positioning to be group inapplicable within one or more cycles.

[0145] The WTRU may (e.g., first) receive SL-PRS from each of one or more member WTRUs in the group, e.g., for each of one or more cycles based on SL-PRS Rx. At 426, the WTRU may increment a count (e.g., a counter) of consecutive indications. The WTRU may (e.g., then) determine (e.g., consider) that one or more positioning groups are group applicable, e.g., if the quality of the SL-PRS received from at least N member WTRUs at 428 meets one or more thresholds (e.g., LOS / NLOS > threshold). The WTRU may (e.g., otherwise) determine (e.g., consider) that the one or more groups are group inapplicable for the one or more cycles.

[0146] The WTRU may transmit SL-PRS and / or receive SL-PRS measurement reports from one or more member WTRUs, e.g., for each cycle based on SL-PRS Tx. The WTRU may determine (e.g., consider) that one or more positioning groups are group applicable, e.g., if the reported SL-PRS measurements from at least N member WTRUs meet one or more thresholds (e.g., LOS / NLOS > threshold indicated in the SL-PRS measurement report). The WTRU may determine (e.g., consider) that the one or more groups are group applicable for the one or more cycles. The WTRU may use one or more established positioning groups to determine / deduce one or more positions, e.g., if the count (e.g., consecutive) of group inapplicable indications is less than one or more thresholds. At 430, the WTRU may perform one or more of the following: send a GPUSP indication to one or more other nodes (e.g., the network or a member WTRU), release one or more groups, stop one or more sidelink positioning sessions, perform one or more positioning request transmissions, and / or include one or more WTRUs in a group, e.g., if the count (e.g., consecutive) of group inapplicable indications is greater than or equal to one or more thresholds.

[0147] Figure 5 A flowchart of an example process 500 for link-based sidelink positioning monitoring is illustrated. The anchor WTRU 502 may send SL-PRS 506 to the target WTRU. The anchor WTRU 502 may (e.g., then) receive SL-PRS 508 from the target WTRU 504. The anchor WTRU 502 may (e.g., then) send an SL-PRS measurement report 510 to, e.g., the target WTRU 504. A monitoring cycle 512 may include sending SL-PRS 506, receiving SL-PRS 508, and / or sending an SL-PRS measurement report 510. The number of monitoring cycles 512 may be arbitrary.

[0148] At 514, the target WTRU 504 may determine whether the RSRP of the SL-PRS Rx is greater than a threshold and / or whether the RSRP of the reported SL-PRS is greater than a threshold. The target WTRU 504 may determine at 516 that the link to the anchor WTRU(s) 502 is suitable for sidelink positioning, e.g., if the RSRP of the SL-PRS Rx is greater than a threshold and / or if the RSRP of the reported SL-PRS is greater than a threshold. At 518, the target WTRU 504 may determine that the link to the anchor WTRU(s) 502 is not suitable for sidelink positioning, e.g., if the RSRP of the SL-PRS Rx is not greater than a threshold and / or if the RSRP of the reported SL-PRS is not greater than a threshold. At 520, the target WTRU 504 may determine whether the number of consecutive non-suitable periods is greater than a threshold. At 522, the target WTRU 504 may continue to monitor the link, e.g., if the number of consecutive non-suitable periods is not greater than a threshold. At 524, the target WTRU 504 may perform one or more of the following: send an LPUSP indication to the anchor WTRU(s) 502, declare the link as LPUSP, and / or stop the positioning session with the anchor WTRU(s) 502, e.g., if the number of consecutive non-suitable periods is greater than a threshold.

Claims

1. A first wireless transmit / receive unit (WTRU), comprising: a processor configured to: receive a first sidelink positioning reference signal (SL-PRS) from a second WTRU; determine a signal quality of the first SL-PRS; transmit a second SL-PRS to the second WTRU; receive an SL-PRS measurement report from the second WTRU based on the second SL-PRS transmitted to the second WTRU; determine that the second WTRU is suitable for sidelink link-based positioning based on the signal quality of the first SL-PRS received from the second WTRU and the SL-PRS measurement report; and determine a location of the first WTRU using the second WTRU.

2. The first WTRU according to claim 1, wherein The processor is configured to: determine that the second WTRU is suitable for sidelink link-based positioning when the signal quality of the first SL-PRS is greater than a first threshold and the SL-PRS measurement report indicates that the signal quality of the second SL-PRS transmitted to the second WTRU is greater than a second threshold.

3. The first WTRU according to claim 2, wherein the first threshold or the second threshold is within a predetermined range.

4. The first WTRU according to claim 1, wherein the processor is configured to determine that the second WTRU is not suitable for link-based positioning when one or more of the following are met: the signal quality of the first SL-PRS is less than the first threshold, the SL-PRS measurement report indicates that the signal quality of the second SL-PRS transmitted to the second WTRU is less than the second threshold, the second SL-PRS is not transmitted to the second WTRU, the first SL-PRS from the second WTRU is not received, or the SL-PRS measurement report is not received.

5. The first WTRU according to claim 1, wherein the processor is configured to: determine that the second WTRU is not suitable for link-based positioning for a certain number of consecutive periods; transmit a link persistently unavailable for sidelink positioning (LPUSP) indication based on the number of consecutive periods exceeding a third threshold; and stop a sidelink positioning session with the second WTRU.

6. The first WTRU according to claim 5, wherein During each of the number of consecutive periods, the processor is configured to receive the first SL-PRS, transmit the second SL-PRS, and receive the SL-PRS measurement report.

7. The first WTRU according to claim 5, wherein the LPUSP is transmitted to the second WTRU or a location management function (LMF).

8. The first WTRU according to claim 1, wherein the signal quality of the first SL-PRS includes a line-of-sight (LOS) value or a non-line-of-sight (NLOS) value.

9. The first WTRU according to claim 1, wherein the processor is configured to receive an indication to perform sidelink positioning monitoring.

10. The first WTRU according to claim 1, wherein the processor is configured to transmit an indication to perform sidelink positioning monitoring to a third WTRU.

11. A method performed by a first wireless transmit / receive unit (WTRU), the method comprising: Receive a first sidelink positioning reference signal (SL-PRS) from a second WTRU; Determine the signal quality of the first SL-PRS; Transmit a second SL-PRS to the second WTRU; Receive an SL-PRS measurement report from the second WTRU based on the second SL-PRS transmitted to the second WTRU; Determine that the second WTRU is suitable for sidelink link-based positioning based on the signal quality of the first SL-PRS received from the second WTRU and the SL-PRS measurement report; and Determine the location of the first WTRU using the second WTRU.

12. The method according to claim 11, further comprising: Determine that the second WTRU is suitable for sidelink link-based positioning when the signal quality of the first SL-PRS is greater than a first threshold and the SL-PRS measurement report indicates that the signal quality of the second SL-PRS transmitted to the second WTRU is greater than a second threshold.

13. The method according to claim 12, wherein the first threshold or the second threshold is within a predetermined range.

14. The method according to claim 11, further comprising: Determine that the second WTRU is not suitable for link-based positioning when one or more of the following are satisfied: the signal quality of the first SL-PRS is less than a first threshold, the SL-PRS measurement report indicates that the signal quality of the second SL-PRS transmitted to the second WTRU is less than a second threshold, the second SL-PRS is not transmitted to the second WTRU, the first SL-PRS from the second WTRU is not received, or the SL-PRS measurement report is not received.

15. The method according to claim 11, further comprising: Determine that the second WTRU is not suitable for link-based positioning within a certain number of consecutive periods; Transmit a link continuously unavailable for sidelink positioning (LPUSP) indication based on the number of consecutive periods exceeding a third threshold; and Stop the sidelink positioning session with the second WTRU.

16. The method according to claim 15, wherein, During each of the number of consecutive periods, the method further comprises: Receive a first SL-PRS; Transmit a second SL-PRS; and Receive an SL-PRS measurement report.

17. The method according to claim 15, further comprising: Transmit the LPUSP to the second WTRU or a location management function (LMF).

18. The method according to claim 11, wherein, The signal quality of the first SL-PRS includes a line-of-sight (LOS) value or a non-line-of-sight (NLOS) value.

19. The method according to claim 11, further comprising: Receive an indication to perform sidelink positioning monitoring.

20. The method according to claim 11, further comprising: Transmit an indication to perform sidelink positioning monitoring to a third WTRU.

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