Method and apparatus for power control for sidelink positioning

Abstract

A wireless transmit-receive unit (WTRU) transmits a first SL positioning reference signal (SL-PRS) using an open loop power control (OLPC) formula having a sidelink (SL) or downlink (DL) path loss parameter, and if a reference signal received power (RSRP) measured and transmitted by a peer-to-peer WTRU in response to receiving the first SL-PRS is below a configured threshold RSRP associated with QoS of a positioning service. If so, it is determined that a power offset is applied to the second SL-PRS as a function of QoS of the positioning service. Additional embodiments are disclosed.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims priority to U.S. patent application serial number 63 / 445,533 filed on February 14, 2023 and U.S. patent application serial number 63 / 396,056 filed on August 8, 2023, the contents of which are incorporated herein by reference as if fully set forth herein. Background Art

[0003] For sidelink (SL) positioning reference symbol (SL-PRS) transmission, in order to ensure the QoS of the sidelink positioning service (such as positioning accuracy, latency, reliability), the SL reference signal received power (SL-RSRP) reception requirements of the SL-PRS should be met (for example, the SL-RSRP of the SL-PRS should be greater than a certain threshold). However, the transmission power of the SL-PRS should also be limited to minimize interference to other sidelinks and the radio access network (RAN) air interface (Uu).

[0004] For sidelink communications, open loop power control (OLPC) is supported. For all broadcast types, downlink (DL) path loss is supported, and for unicast, SL path loss is supported. OLPC parameters (e.g., P0, α) are (pre-)configurable per resource pool. For sidelink positioning, it is expected that the minimum received power of the SL-PRS should be guaranteed to meet the QoS (e.g., accuracy) requirements of the positioning service. Using OLPC parameters (pre-)configured per pool may result in low received power of the SL-PRS, which may not meet the QoS requirements of the positioning service. There is a continuous need for solutions on how to perform power control of the SL-PRS to minimize interference to the system and meet the QoS (e.g., accuracy) of the positioning (POS) service. Summary of the invention

[0005] In some aspects, a user equipment (UE) (also interchangeably referred to herein as a wireless transmit receive unit (WTRU)) uses the OLPC formula to derive its transmit power for SL-PRS transmission. However, if the SL-PRS measurement report indicates that the received power is insufficient to guarantee the QoS of the positioning service, the WTRU may adjust its transmit power (e.g., increase the delta_offset). Upon receiving the SL-PRS measurement report, the WTRU determines whether to derive the Tx power of its SL-PRS using only the OLPC parameter set or additionally applying the delta_offset as a function of the QoS of the positioning service based on whether the reported SL-RSRP is greater than a (pre-)configured SL-RSRP threshold.

[0006] In another aspect, the WTRU determines which sidelink transmission (e.g., SL-PRS and / or data) to measure for SL Reference Signal Received Power (SL-RSRP) for OLPC based on the (pre-)configuration type of the resource pool used to send the SL-PRS.

[0007] In yet another aspect, the WTRU determines which SL pathloss to use to derive the Tx power of the SL-PRS based on the availability of each SL pathloss and the (pre-)configured priority / priority of each pathloss.

[0008] In another aspect, the WTRU determines the transmit power of the SL-PRS based on the transmit power of the physical sidelink shared channel (PSSCH) and the (pre-)configured power boost for the SL-PRS.

[0009] In yet another aspect, for closed loop power control (CLPC), a receiving (Rx) WTRU determines whether to include a received SL-PRS in its measurement report based on the SL-RSRP of the received SL-PRS. If the received SL-RSRP is less than a threshold, the Rx WTRU feeds back a negative acknowledgement (NACK) (e.g., using a physical sidelink feedback channel (PSFCH)) to request an additional SL-PRS transmission from the Tx WTRU.

[0010] An example implementation of a wireless transmit receive unit (WTRU) that performs open-loop power control is described herein. In one example, the WTRU may determine whether to apply a power offset as a function of the QoS of a positioning service in an open-loop power control (OLPC) formula for the SL-PRS when the reported SL-RSRP of the SL-PRS is less than a threshold. Specifically, the WTRU may perform the following process to determine the SL-PRS. First, the WTRU may be pre-configured with the following OLPC power control parameters: SL and DL path loss compensation (e.g., α and P0 for SL and DL); a received SL-RSRP threshold associated with the positioning service; and an offset in the OLPC formula as a function of the QoS of the positioning service, referred to as delta_offset. Next, the WTRU performs SL-PRS transmission at a first power using the (pre-)configured SL and DL path loss compensation. The WTRU then receives a sidelink positioning measurement report (e.g., including SL-RSRP) from the Rx WTRU. Next, the WTRU may perform the following process for a new SL-PRS transmission: If the reported SL-RSRP is greater than the threshold, the WTRU sends the next SL-PRS using the same SL and DL path loss compensation parameters. Otherwise, the WTRU increases the transmit power parameters by applying an offset based on the QoS of the location service in the formula. If the Tx power reaches its maximum value, the WTRU may perform one or any of the following operations: change the SL-PRS pattern (e.g., increase the comb size); change the resource pool; and / or notify another node (e.g., a gNB or another WTRU).

[0011] In another example embodiment, a Tx WTRU that performs closed loop power control (CLCP) is described herein. The Tx WTRU may perform CLPC for the SL-PRS. The Tx WTRU may determine to adjust its SL-PRS transmit power based on a SL-RSRP threshold for the SL-PRS, a number of SL-PRS measurement resources, and SL-PRS feedback from a receiving WTRU. Specifically, the Tx WTRU may perform the following process to determine the SL-PRS transmit power. First, the WTRU may be (pre-)configured with the following parameters: a received SL-RSRP threshold for the SL-PRS and a number of SL-PRS measurement resources for which the received SL-RSRP is greater than the threshold, and an offset for each power adjustment step. Next, the WTRU performs a SL-PRS transmission and indicates the RSRP threshold to the Rx WTRU (e.g., in an SCI associated with the SL-PRS transmission) using an initial Tx power. The WTRU then receives feedback from the Rx WTRU regarding the SL-PRS received power. Next, the WTRU performs the following process for the new SL-PRS transmission: If the Rx WTRU indicates that the received SL-RSRP is less than the threshold, then increase the Tx power using the (pre-)configured offset. Otherwise, use the same Tx power for the new SL-PRS transmission. Finally, the WTRU performs the SL-PRS transmission using the determined power.

[0012] An example implementation of an Rx WTRU that performs closed-loop power control of a SL-PRS is described. The Rx WTRU may determine whether to include the received SL-PRS in a measurement report based on the received SL-RSRP of the received SL-PRS. In the event that the received SL-RSRP is less than a threshold, the Rx WTRU feeds back the SL-PRS received power to the Tx WTRU, indicating that the SL-RSRP is less than the threshold (e.g., using a one-bit indication of a physical sidelink feedback channel (PSFCH)). Specifically, the Rx WTRU may perform the following process for the CLPC received by the SL-PRS. The WTRU may be (pre-)configured with the number of SL-PRS measurement resources for which the received SL-RSRP is greater than the threshold. The WTRU receives a SL-PRS with an RSRP threshold (e.g., an index in an RSRP threshold table) from the Tx WTRU, the RSRP threshold being indicated in the associated sidelink control information (SCI). If the SL-RSRP measured on the received SL-PRS is less than a threshold, the Rx WTRU indicates this to the Tx WTRU (e.g., using a one-bit indication on the PSFCH). Otherwise, the Rx WTRU includes the SL-PRS resources in the measurement report until the number of measured SL-PRS resources with a SL-RSRP greater than the SL-RSRP threshold in the SL-PRS resources is greater than a specified threshold. Finally, the Rx WTRU performs a SL-PRS measurement report and sends it to the Tx WTRU. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] A more detailed understanding may be obtained from the following description given by way of example in conjunction with the accompanying drawings, in which like reference numerals indicate like elements, and in which:

[0014] Figure 1A is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented;

[0015] Figure 1B is an example of an embodiment in which Figure 1A A system diagram of an example wireless transmit / receive unit (WTRU) for use within an illustrated communication system;

[0016] Figure 1C is an example of an embodiment in which Figure 1A A system diagram of an example Radio Access Network (RAN) and an example Core Network (CN) used within the illustrated communication system;

[0017] Figure 1D is an example of an embodiment in which Figure 1A A system diagram of another example RAN and another example CN used within the illustrated communication system;

[0018] Figure 2 is a signal timing diagram of a sidelink positioning reference signal (SL-PRS) according to an implementation scheme; and

[0019] Figure 3 is a flowchart illustrating in detail a method for adjusting the transmission power of SL-PRS according to an embodiment. DETAILED DESCRIPTION

[0020] Figure 1A 1 is a diagram illustrating an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc. to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content through sharing of system resources (including wireless bandwidth). 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 discrete Fourier transform spread OFDM (ZT-UW-DFT-S-OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, and filter bank multi-carrier (FBMC), etc.

[0021] like Figure 1AAs shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104, a core network (CN) 106, 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 (STA)) may be configured to send and / or receive wireless signals and may include user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smart phone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated process chain environment), consumer electronic devices, and devices operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0022] The communication system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node B, an evolved Node B (eNB), a Home Node B, a Home evolved Node B, a Next Generation Node B (such as a gNode B (gNB)), a New Radio (NR) Node B, a site controller, an access point (AP), a wireless router, and the like. Although the base stations 114a, 114b are each depicted as a single element, it should be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0023] Base station 114a may be part of RAN 104, which may also include other base stations and / or network elements (not shown), such as base station controllers (BSC), radio network controllers (RNC), and relay nodes. Base station 114a and / or base station 114b may be configured to send and / or receive wireless signals on one or more carrier frequencies, which may be referred to as cells (not shown). These frequencies may be in a licensed spectrum, an unlicensed spectrum, or a combination of a licensed spectrum and an unlicensed spectrum. A cell may provide coverage of wireless services to a specific geographic area, which may be relatively fixed or may change over time. The cell may be further divided into cell sectors. For example, the cell associated with base station 114a may be divided into three sectors. Therefore, in one embodiment, base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In an embodiment, base station 114a may employ multiple-input multiple-output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to send and / or receive signals in a desired spatial direction.

[0024] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0025] More specifically, as noted above, the communication system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, and SC-FDMA, among others. For example, the base station 114a in the RAN 104 and the WTRUs 102a, 102b, 102c may implement a radio technology, such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), that may use Wideband CDMA (WCDMA) to establish the air interface 116. 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 ​​Uplink (UL) Packet Access (HSUPA).

[0026] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA) that may establish the air interface 116 using Long Term Evolution (LTE) and / or Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-APro).

[0027] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology (such as NR radio access) that may establish the air interface 116 using NR.

[0028] 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 together implement LTE radio access and NR radio access, 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 transmitted to / from multiple types of base stations (e.g., eNBs and gNBs).

[0029] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), and GSM EDGE (GERAN).

[0030] Figure 1AThe base station 114b in may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in local areas such as commercial venues, homes, vehicles, campuses, industrial facilities, sky corridors (e.g., for use by drones), and roads. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology (such as IEEE 802.11) to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology (such as IEEE 802.15) to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a picocell or a femtocell. As Figure 1A As shown, the base station 114 b may have a direct connection to the Internet 110. Therefore, the base station 114 b may not need to access the Internet 110 via the CN 106.

[0031] The RAN 104 may be in communication with the CN 106, which may be any type of network configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not described in detail in the specification, the CN 106 may be configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. Figure 1A Although not shown in the figure, it will be appreciated that the RAN 104 and / or the CN 106 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 or a different RAT. For example, in addition to being connected to the RAN 104, which may utilize NR radio technology, the CN 106 may also be in communication with another RAN (not shown) that employs GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0032] The CN 106 may also act as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and / or the Internet Protocol (IP) in the TCP / IP Internet protocol suite. The networks 112 may include wired communication networks and / or wireless communication networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 or a different RAT.

[0033] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks via different wireless links). Figure 1A The illustrated WTRU 102c may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0034] Figure 1B is a system diagram illustrating an example WTRU 102. Figure 1B As shown, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0035] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), any other type of integrated circuit (IC), state machine, etc. The processor 118 may perform signal decoding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. Although Figure 1B The processor 118 and the transceiver 120 are depicted as separate components, but it is understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0036] The send / receive element 122 may be configured to send a signal to a base station (e.g., base station 114a) or receive a signal from a base station via an air interface 116. For example, in one embodiment, the send / receive element 122 may be an antenna configured to send and / or receive an RF signal. In an embodiment, the send / receive element 122 may be a transmitter / detector configured to send and / or receive, for example, an IR, UV, or visible light signal. In another embodiment, the send / receive element 122 may be configured to send and / or receive both an RF signal and an optical signal. It should be understood that the send / receive element 122 may be configured to send and / or receive any combination of wireless signals.

[0037] Although the transmit / receive element 122 Figure 1B Although depicted as a single element in the figure, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0038] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and to demodulate signals received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. For example, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0039] The processor 118 of the WTRU 102 may be coupled to and may receive user input data from a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from and store data in any type of suitable memory, such as a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, and a secure digital (SD) memory card, among others. In other embodiments, the processor 118 may access information from and store data in a memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0040] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel cadmium (NiCd), nickel zinc (NiZn), nickel metal hydride (NiMH), lithium ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0041] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or in lieu of the information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by any suitable location-determination method while remaining consistent with an embodiment.

[0042] The processor 118 may also be coupled to other peripherals 138, which may include one or more software modules and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, Modules, frequency modulation (FM) radio units, digital music players, media players, video game player modules, Internet browsers, virtual reality and / or augmented reality (VR / AR) devices and activity trackers, etc. The peripheral device 138 may include one or more sensors. The sensor may be one or more of the following: a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geographic location sensor, an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and a humidity sensor, etc.

[0043] The WTRU 102 may include a full-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with specific subframes for both UL (e.g., for transmission) and DL (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 signal processing performed by hardware (e.g., a choke) or via a processor (e.g., a separate processor (not shown) or via the processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with specific subframes for both UL (e.g., for transmission) or DL ​​(e.g., for reception)) may be concurrent and / or simultaneous.

[0044] Figure 1C 1 is a system diagram illustrating the RAN 104 and the CN 106 in accordance with an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0045] The RAN 104 may include evolved Node-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of evolved Node-Bs while remaining consistent with an embodiment. The evolved Node-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the evolved Node-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the evolved Node-B 160a, for example, may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0046] Each of the evolved Node Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, and scheduling of users in the UL and / or DL, among other things. Figure 1C As shown, the eNode-Bs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0047] Figure 1C The illustrated CN 106 may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (PGW) 166. Although the foregoing elements are depicted as part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0048] The MME 162 may be connected to each of the evolved Node-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, and selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0049] The SGW 164 may be connected to each of the evolved Node-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring the user plane during an inter-evolved Node-B handover, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, and managing and storing the context of the WTRUs 102a, 102b, 102c.

[0050] The SGW 164 may be connected to the PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0051] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may be in communication with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers.

[0052] Although the WTRU Figures 1A to 1D Although described as wireless terminals, it is contemplated that in certain representative embodiments, such terminals may (eg, temporarily or permanently) use a wired communications interface with a communications network.

[0053] In a representative embodiment, the other network 112 may be a WLAN.

[0054] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for a BSS and one or more stations (STAs) associated with the AP. The AP may have access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic to and / or carries traffic away from the BSS. Traffic originating from outside the BSS and going to the STA may arrive through the AP and may be delivered to the STA. Traffic originating from the STA and going to a destination outside the BSS may be transmitted to the AP to be delivered to the corresponding destination. Traffic between STAs within the BSS may be transmitted through the AP, for example, wherein the source STA may transmit traffic to the AP, and the AP may deliver traffic to the destination STA. Traffic between STAs within the BSS may be considered and / or referred to as point-to-point traffic. Point-to-point traffic may be transmitted between the source STA and the destination STA (e.g., directly between them) using a direct link setup (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunnel DLS (TDLS). A WLAN using an independent BSS (IBSS) mode may not have an AP, and STAs within or using the IBSS (eg, all STAs in the STA) may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad hoc" communication mode.

[0055] When using the 802.11ac infrastructure operation mode or a similar operation mode, the AP may send beacons on a fixed channel (such as a primary channel). The primary channel may be a fixed width (e.g., a 20 MHz wide bandwidth) or a dynamically set width. The primary channel may be an operating channel of the BSS and may be used by the STA to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access / collision avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. For CSMA / CA, a STA (e.g., each STA) (including the AP) may listen to the primary channel. If the primary channel is listened / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0056] High throughput (HT) STAs may communicate using a 40 MHz wide channel (eg, via a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels) to form a 40 MHz wide channel.

[0057] Very high throughput (VHT) STA can support 20MHz, 40MHz, 80MHz and / or 160MHz wide channels. 40MHz channels and / or 80MHz channels can be formed by combining continuous 20MHz channels. 160MHz channels can be formed by combining 8 continuous 20MHz channels, or by combining two non-continuous 80MHz channels (this can be called 80+80 configuration). For 80+80 configuration, after channel coding, the data can pass through a segment parser that can divide the data into two streams. Each stream can be processed by inverse fast Fourier transform (IFFT) and time domain processing separately. These streams can be mapped to two 80MHz channels, and the data can be sent by the transmitter STA. At the receiver of the receiver STA, the above-mentioned operation for the 80+80 configuration can be reversed, and the combined data can be transmitted to the medium access control (MAC).

[0058] 802.11af and 802.11ah support operating modes below 1GHz. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah relative to those used in 802.11n and 802.11ac. 802.11af supports 5MHz, 10MHz, and 20MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support meter type control / machine type communication (MTC), such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support for (e.g., only support for) certain bandwidths and / or limited bandwidths. MTC devices may include batteries with battery life above a threshold (e.g., to maintain very long battery life).

[0059] WLAN systems that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) include channels that can be designated as primary channels. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA (which supports the minimum bandwidth operating mode) from all STAs operating in the BSS. In the example of 802.11ah, for STAs (e.g., MTC-type devices) that support (e.g., only support) a 1MHz mode, the primary channel may be 1MHz wide, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) settings may depend on the state of the primary channel. If the primary channel is busy, for example, because a STA (which only supports a 1MHz operating mode) is transmitting to the AP, all available bands may be considered busy even if most of the available bands remain idle.

[0060] In the United States, the available frequency band for 802.11ah is 902MHz to 928MHz. In South Korea, the available frequency band is 917.5MHz to 923.5MHz. In Japan, the available frequency band is 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz, depending on the country code.

[0061] Figure 1D1 is a system diagram illustrating the RAN 104 and the CN 106 in accordance with an embodiment. As noted above, the RAN 104 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0062] The RAN 104 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 104 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, the gNBs 180a, 180b may utilize beamforming to send signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a may, for example, use multiple antennas to send wireless signals to and / or receive wireless signals from the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, gNB 180a may transmit multiple component carriers to WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum, while the remaining component carriers may be on licensed spectrum. In an embodiment, gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0063] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with parameter sets that may be scalable. For example, OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or Transmission Time Intervals (TTIs) of varying or scalable lengths (e.g., containing different numbers of OFDM symbols and / or varying absolute time lengths over time).

[0064] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c while not accessing other RANs (e.g., such as the eNodeBs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may use one or more of the gNBs 180a, 180b, 180c as mobility anchor points. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect with the gNB 180a, 180b, 180c while also communicating / connecting with another RAN, such as the eNodeB 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNodeBs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNodeB 160a, 160b, 160c may act as a mobility anchor for the WTRUs 102a, 102b, 102c, and the gNB 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0065] Each of the gNBs 180a, 180b, 180c may be associated with a specific cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and / or DL, support of network slicing, interworking between DC, NR and E-UTRA, routing of user plane data towards a user plane function (UPF) 184a, 184b and routing of control plane information towards an access and mobility management function (AMF) 182a, 182b, etc. Figure 1D As shown, gNBs 180a, 180b, and 180c may communicate with each other via an Xn interface.

[0066] Figure 1DThe illustrated CN 106 may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and possible data networks (DNs) 185a, 185b. Although the aforementioned elements are depicted as part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0067] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via the N2 interface and may act as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRU 102a, 102b, 102c, support of network slicing (e.g., handling of different protocol data unit (PDU) sessions with different requirements), selecting a specific SMF 183a, 183b, management of registration areas, termination of non-access stratum (NAS) signaling, and mobility management, etc. The AMF 182a, 182b may use network slicing to customize CN support for the WTRU 102a, 102b, 102c based on the type of services utilized by the WTRU 102a, 102b, 102c. 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, and services for MTC access. The AMF 182a, 182b may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies such as WiFi.

[0068] The SMF 183a, 183b may be connected to the AMF 182a, 182b in the CN 106 via the N11 interface. The SMF 183a, 183b may also be connected to the UPF 184a, 184b in the CN 106 via the N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b, and configure traffic routing through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions such as managing and allocating WTRU IP addresses, managing PDU sessions, controlling policy enforcement and QoS, and providing DL data notifications. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0069] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via the N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering DL packets, and providing mobility anchoring, etc.

[0070] The CN 106 may facilitate communications with other networks. For example, the CN 106 may include or may communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to the DNs 185a, 185b via the UPFs 184a, 184b via the N3 interfaces to the UPFs 184a, 184b and the N6 interfaces between the UPFs 184a, 184b and the local DNs 185a, 185b.

[0071] Given that Figures 1A to 1D as well as Figures 1A to 1D Corresponding to the description of the present invention, one or more or all of the functions described herein with reference to one or more of the following items may be performed by one or more simulation devices (not shown): WTRU102a to 102d, base station 114a to 114b, evolved Node B 160a to 160c, MME 162, SGW 164, PGW 166, gNB180a to 180c, AMF 182a to 182b, UPF 184a to 184b, SMF 183a to 183b, DN 185a to 185b and / or any other device described herein. The simulation device may be one or more devices configured to mimic one or more or all of the functions described herein. For example, the simulation device can be used to test other devices and / or simulate network and / or WTRU functions.

[0072] The simulation device may be designed to implement one or more tests of other devices in a laboratory environment and / or in an operator network environment. For example, one or more simulation devices may perform one or more functions or all functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. One or more simulation devices may perform one or more functions or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. A simulation device may be directly coupled to another device for the purpose of testing and / or performing tests using over-the-air wireless communications.

[0073] 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 a non-deployed (e.g., testing) wired and / or wireless communication network to implement testing of one or more components. One or more simulation devices can be test equipment. Direct RF coupling and / or wireless communication via RF circuits (e.g., which can include one or more antennas) can be used by the simulation device to send and / or receive data.

[0074] Wireless protocols have been specified to support sidelink (SL) transmissions, in particular between a vehicle and another recipient. This concept is referred to herein as vehicle-to-everything (V2X). In the example of V2X, resources for sidelink transmission / reception are structured as resource pools. A resource pool may include a set of contiguous frequency resources that repeat in time following a bitmap pattern. A WTRU may be configured with one or more resource pools. For a WTRU within coverage, a resource pool may be configured via a system information block (SIB) or a radio resource control (RRC) message. For a WTRU outside coverage, a resource pool may be (pre-)configured.

[0075] Each sidelink transmission may span a time slot, including at least one of a physical sidelink shared channel (PSSCH) and a physical sidelink control channel (PSCCH). PSSCH and PSCCH use frequency division multiplexing (FDM) and time division multiplexing (TDM). Sidelink control information (SCI) may be divided into two parts, which are a first-level SCI and a second-level SCI. The first-level SCI indicates the resources used for the sidelink transmission, the QoS of the transmission (e.g., priority), a demodulation reference signal (DMRS), a phase tracking reference signal (PTRS) for the sidelink transmission, and a second SCI format. The second-level SCI may indicate the remaining control information. SCI may be used to reserve resources for future transmissions within a resource pool.

[0076] From the sidelink scheduling perspective, the sidelink resources may be scheduled by the RAN network (i.e., Mode 1) or selected autonomously by the WTRU (i.e., Mode 2). If the WTRU performs Mode 2 scheduling, the WTRU may perform sensing by decoding the SCI from other WTRUs before selecting the sidelink resources to avoid selecting resources reserved by other WTRUs.

[0077] The Sidelink Channel State Information Reference Signal (SL-CSI-RS) may be supported for unicast to support the Tx WTRU in determining Tx parameters (e.g., power and rank). The Tx WTRU may indicate the presence of the SL-CSI-RS by using the SCI. The CSI-RS transmission will trigger a CSI report, and the CSI reporting delay may be configurable via PC5 RRC. Each report may be associated with one SL-CSI-RS transmission.

[0078] In V2X, OLPC is supported, in which the WTRU can derive its transmit power based on DL path loss and / or SL path loss. Specifically, for groupcast / broadcast, OLPC only supports DL path loss. In general, DL path loss is used to protect Uu transmission. For unicast, both DL path loss and SL path loss can be used to derive the transmit power of the WTRU. The minimum power obtained from the DL path loss and SL path loss equations can be used for transmission. In order to derive the SL path loss, the Rx WTRU (in the DMRS of the PSSCH) performs L3-SL-RSRP measurement and reports the measurement results to the Tx WTRU via PC5RRC.

[0079] Uu positioning may include specified DL-based, UL-based, and DL+UL-based positioning methods. In the DL-based positioning method, the DL-PRS is transmitted to the WTRU from multiple transmit receive points (TRPs). The WTRU will observe and measure the downlink signals from the TRPs. For the WTRU-B method, the WTRU can calculate its positioning, and for the WTRU-A method, the WTRU can return the downlink measurement results to the network. For the angle-based method, the WTRU can report the angle of arrival (AoA) and RSRP of the downlink signal from the TRP. For the timing-based method, the WTRU can report the received signal time difference (RSTD). The above methods require the transmission timing synchronization between the TRPs. The positioning calculation errors using these methods are mainly caused by synchronization errors and multipath reflections.

[0080] In the uplink positioning method, the WTRU transmits the UL-PRS configured by RRC for positioning to the TRP. The network can then calculate the positioning of the WTRU based on the coordination of all TRPs that receive UL-PRS from the WTRU.

[0081] In the UL and DL based methods, the WTRU measures the Rx-Tx time difference between the received DL-PRS and the transmitted UL-PRS. This Rx-Tx time difference and RSRP are reported to the network, which can then coordinate the TRP to calculate the WTRU's location.

[0082] Example sidelink channels for power control are described herein. The power control parameters or methods described herein may be applicable to any sidelink physical channel, including but not limited to SL-PRS, PSSCH, PSCCH, PSFCH, sidelink synchronization signal block (S-SSB) and physical sidelink broadcast channel (PSBCH). The transmit power of the sidelink may be the transmit power of the above-mentioned sidelink channel or the transmit power of the sidelink reference signal (e.g., SL-PRS, DM-RS of PSSCH, DM-RS of PSCCH, CSI-RS, PTRS). In the following, QoS parameters may be used interchangeably as QoS, QoS parameter, one or a QoS parameter, at least one QoS parameter, one of the QoS parameters, or any combination of these parameters.

[0083] The WTRU may use one or any of the following reference signals as SL-PRS: DMRS of PSSCH and / or PSCCH; Sidelink Synchronization Signal (SLSS) (S-PSS, S-SSS); PTRS; Sidelink Channel State Information Reference Signal (SL-CSI-RS); Physical Sidelink Feedback Channel (PSFCH); and / or any new reference signal designed for positioning purposes.

[0084] In an example, the WTRU may determine the QoS of the positioning service. For example, the WTRU may determine the QoS of the positioning service. The QoS of the positioning service may be used to determine one or more of the priority, accuracy, latency, reliability, minimum communication range (MCR), and / or positioning availability requirements of the positioning service. The QoS of the positioning service may be determined based on one or any combination of the following: (pre-)configuration in the resource pool and / or the WTRU; one or more parameters for SL-PRS transmission and / or reception; SL-PRS reception requirements; implicit / explicit indication from another node; one or more parameters for DL-PRS reception and / or UL-PRS transmission (pre-)configured for the WTRU or conveyed to the WTRU; one or more parameters for SL-PRS measurement reporting; one or more parameters for DL-PRS measurement reporting and / or positioning methods.

[0085] The QoS positioning may be determined using a (pre-)configuration in a resource pool and / or in the WTRU. For example, in a shared resource pool between SL-PRS and sidelink data communications, the WTRU may be (pre-)configured with a priority associated with a SL-PRS transmission. The WTRU may then indicate the (pre-)configured priority of the sidelink positioning service in one or more transmissions associated with the SL-PRS transmission.

[0086] The QoS positioning may be determined using one or more parameters of the SL-PRS transmission and / or reception. For example, the WTRU may determine the QoS (e.g., accuracy / priority) of the positioning service based on the bandwidth of the SL-PRS. Specifically, the WTRU may be (pre-)configured with one or more QoS levels of the positioning service, where each QoS level may be associated with a bandwidth of the SL-PRS. The WTRU may then determine the QoS of the positioning service based on the bandwidth of the SL-PRS transmission / reception.

[0087] For example, SL-PRS reception requirements (e.g., minimum received SL-RSRP, maximum received timing error) may be used to determine QoS positioning. For example, the WTRU may determine one or more QoS (e.g., accuracy / priority) of the positioning service based on the SL-RSRP reception requirements of the SL-PRS. Specifically, the WTRU may be (pre-)configured with one or more QoS levels of the positioning service, where each QoS level may be associated with a SL-RSRP reception level of the SL PRS. The WTRU may then determine the QoS of the positioning service based on the required SL-PRSP level of the SL PRS.

[0088] In some embodiments, QoS positioning may be determined using implicit / explicit indications from another node (e.g., another WTRU or gNB). For example, the WTRU may implicitly / explicitly receive one or more QoS parameters for positioning services from another WTRU or gNB. The WTRU may receive one or more QoS parameters based on receipt of SL-PRS configuration (e.g., priority, bandwidth, comb size, number of repetitions, periodicity), SL-PRS measurement report configuration (e.g., priority, periodicity, latency).

[0089] In other embodiments, the QoS positioning may be determined using one or more parameters for DL-PRS reception and / or UL-PRS transmission that are (pre)configured for the WTRU or delivered to the WTRU. For example, for hybrid sidelink and Uu positioning, the WTRU may determine the QoS (e.g., accuracy / priority) of the positioning service based on the bandwidth of the UL-PRS and / or DL-PRS. Specifically, the WTRU may be (pre)configured with one or more QoS levels for the positioning service, where each QoS level may be associated with a bandwidth of the UL-PRS and / or DL-PRS. The WTRU may then determine the QoS of the positioning service based on the bandwidth of the SL-PRS transmission / reception.

[0090] In one example, one or more parameters (e.g., priority, latency, periodicity) of a SL-PRS measurement report may be used to determine QoS positioning. In another example, one or more parameters (e.g., priority, latency, periodicity) for a DL-PRS measurement report may be used to determine QoS positioning. In yet another example, a positioning method may be used to determine QoS positioning. For example, the WTRU may be (pre)configured with one or more QoS parameters associated with a positioning method. For example, the WTRU may be (pre)configured with a priority associated with each positioning method.

[0091] In an embodiment of the method for open loop power control, in one example, the WTRU may be pre-configured with one or a combination of parameters for performing power control (such as open loop power control). In an example, the WTRU may be (pre-)configured with one or any combination of the following parameters. The WTRU may be (pre-)configured with P C,MAX , which may indicate the maximum transmit power in carrier c. For example, the WTRU may be (pre-)configured with P C,MAX,CBR , which may indicate the maximum transmit power in carrier c as a function of the channel busy ratio (CBR) of the resource pool. In one example, the WTRU may be (pre-)configured with P C,MAX,QoS , which may indicate the maximum transmit power for each QoS of the location service. In one example, the WTRU may be (pre-)configured with P C,MAX,MCR , which may indicate the maximum transmit power for each communication range between the sender and the receiver. In an example, the WTRU may be (pre-)configured with P C,MAX,UEclass , which may indicate the maximum transmit power for a WTRU class. In another example, the WTRU may be (pre-)configured with P o,,QoS, which may indicate a nominal transmit power (e.g., target receive power) for OLPC. The nominal transmit power may be (pre-)configured with different values ​​for sidelink path loss, downlink path loss for unicast, multicast, and broadcast. The nominal transmit power may also be configured as a function of the QoS of the location service.

[0092] In another example, the WTRU may be (pre-)configured with an α QoS , which may indicate a scaling factor for path loss compensation in OLPC. The scaling factor may be (pre)configured with different values ​​for sidelink path loss, downlink path loss for unicast, multicast and broadcast. The scaling factor may be (pre)configured as a function of the QoS of the location service. In an example, the WTRU may be (pre)configured with PL SL , which may indicate the sidelink path loss. The WTRU may be (pre-)configured with PL DL , which may indicate the downlink path loss. In one example, the WTRU may be (pre-)configured with M PSSCH , which may indicate the number of resource elements (REs) / physical resource blocks (PRBs) used for data communication. The WTRU may be (pre-)configured with M PSCCH , which may indicate the number of REs / PRBs used for control channels. In one example, the WTRU may be (pre-)configured with M SL-PRS , which may indicate the number of RE / PBRs used for SL-PRS. In one example, the WTRU may be (pre-)configured with Δ QoS , which may indicate a power offset for the QoS level used for the sidelink location service, the power offset may be (pre)configured with different values ​​for unicast, multicast, and broadcast. In one example, the WTRU may be (pre)configured with Δ SL-PRS pattern , which may indicate the power offset used for each SL-PRS pattern. The WTRU may also determine its transmit power based on a function of one of the OLPC parameters or any combination of OLPC parameters.

[0093] In another example, the WTRU may determine a transmit power scheme. For example, the WTRU may determine which power control scheme to use (e.g., which set of power control parameters and values ​​associated with each parameter to use in Tx power calculations, whether to use OLPC or CLPC, whether to use fixed power or variable power, etc.) based on one or any combination of the following: the type of broadcast associated with the positioning service; the number of WTRUs in the positioning group for groupcast-based sidelink positioning; the multiplexing scheme of SL-PRS with other transmissions; whether SL-PRS reception indication / report is enabled / disabled; and / or an indication from another node.

[0094] In an example, the WTRU may determine which power control scheme to use based on the type of broadcast associated with the location service. For example, the WTRU may use a QoS power offset (Δ QoS ). However, the WTRU may not use Δ QoS For example, the WTRU may use SL path loss for unicast, and it may not use SL path loss for other broadcasts (eg, broadcast / multicast).

[0095] In one example, the WTRU may determine which power control scheme to use based on the number of WTRUs in the positioning group for groupcast-based sidelink positioning. For example, if the number of WTRUs in the sidelink positioning group is less than a threshold, the WTRU may use the SL path loss in the OLPC formula; otherwise, the WTRU may not use the SL path loss.

[0096] In another example, the WTRU may determine which power control scheme to use based on the multiplexing scheme of the SL-PRS with other transmissions. For example, if the SL-PRS is multiplexed with another transmission (e.g., another SL-PRS), the WTRU may use the SL path loss for OLPC. Otherwise, the WTRU may not use the SL path loss in the OLPC formula (e.g., the WTRU may use the maximum transmit power).

[0097] In another example, the WTRU may determine which power control scheme to use based on whether the SL-PRS received indication / report is enabled / disabled. For example, the WTRU may be (pre-)configured with two OLPC formulas, one of which may be used for OLPC when feedback of SL-PRS received power is enabled, and the other formula may be used for OLPC when feedback of SL-PRS received power is disabled.

[0098] In an example, the WTRU may determine which power control scheme to use based on an indication from another node (e.g., another WTRU or a gNB). For example, the WTRU may receive an indication from another node (e.g., another WTRU or a gNB) to use a certain OLPC formula. For example, the WTRU may receive an indication from another node (e.g., another WTRU or a gNB) to use a certain OLPC parameter set (e.g., Δ QoS ) indication. The WTRU may then use the indicated parameters to determine its transmit power.

[0099] In another example, the WTRU may determine which power control scheme to use based on the transmission parameters of the SL-PRS. For example, the WTRU may determine the power control scheme based on the SL-PRS configuration (e.g., frequency range, repetition factor) and / or positioning method (e.g., SL-AoA, round trip time (RTT), received signal time difference (RSTD)). The transmission parameter configuration of the SL-PRS may include at least one of the following parameters: the number of symbols, the transmission power, the number of PRS resources included in the SL-PRS resource set, the muting pattern of the SL-PRS (for example, the muting pattern may be expressed via a bitmap), the periodicity, the type of SL-PRS (for example, periodic, semi-persistent or non-periodic), the time slot offset for periodic transmission of PRS, the vertical shift of the SL-PRS pattern in the frequency domain, the time gap during repetition, the repetition factor, the RE (resource element) offset, the comb pattern, the comb size, the spatial relationship, the QCL information for the SL-PRS (for example, QCL target, QCL source), the number of TRP / anchor WTRUs, the absolute radio frequency channel number (ARFCN), the subcarrier spacing, the expected RSTD, the uncertainty in the expected RSTD, the starting physical resource block (PRB), the bandwidth, the BWPID, the number of frequency layers, the start / end time of the SL-PRS transmission, the on / off indicator for the PRS, the TRP ID, the PRS ID, the cell ID, the global cell ID, and the applicable time window. The WTRU may apply the PRS configuration on the condition that the current time is within the applicable time window.

[0100] In various embodiments, the WTRU may adjust its transmit power. Specifically, the WTRU may implement one or any combination of the following parameters or schemes related to power adjustment.

[0101] In one example, the WTRU may increase / decrease its transmit power by an offset (e.g., Δ QoS ) to adjust its transmit power. The WTRU may additionally or alternatively adjust its transmit power by applying a different function of the OLPC formula (e.g., using the nominal transmit power P o,,QoS and the scaling factor α QoS Alternatively or additionally, the WTRU may adjust its transmit power by adding an offset to the OLPC formula, or the WTRU may adjust its transmit power by removing the offset from the OLPC formula.

[0102] In one example, the WTRU may adjust its transmit power by changing the transmit power scheme. In one method, the WTRU may change a set of power control parameters in the OLPC formula. In another method, the WTRU may change the value of one or more OLPC parameters.

[0103] In various embodiments, the WTRU may adjust its transmit power by performing power adjustments based on one or any combination of the following triggering events: (i) receiving an implicit or explicit indication to increase or decrease transmit power from another node; (ii) receiving a measurement report from another WTRU, (iii) not receiving a measurement report or indication from another WTRU; (iv) experiencing an opportunity for coverage state; (v) changing the RRC state; (vi) enabling or disabling the SL-PRS reception indication; (vii) the CBR is greater than or less than a threshold; (viii) the WTRU changes the multiplexing of SL-PRS transmissions with other transmissions; or (ix) when the number of SL-PRS transmissions in a time period is greater than or less than a threshold.

[0104] In one example, when the WTRU receives an implicit / explicit indication from another node to increase / decrease transmit power, the WTRU may perform power adjustment.

[0105] In another example, the WTRU may perform power adjustment when the WTRU receives a measurement report from another WTRU, which may implicitly / explicitly indicate that the received power is less than / greater than a threshold. For example, the WTRU may receive a SL-PRS measurement report from an Rx WTRU. In one approach, if the measured SL-RSRP is less than a threshold, the WTRU may increase its transmit power by Δ QoS , which may be a function of the QoS of the location service. Otherwise, if the measured SL-RSRP is greater than the threshold, the WTRU may maintain the same transmit power (e.g., the WTRU may not apply a power offset Δ in the OLPC formula QoS ). The SL-RSRP threshold may be (pre-)configured as a function of the QoS of the positioning service.

[0106] In another method, the WTRU may also determine whether to use an offset Δ_QoS based on the CBR of the resource pool. Specifically, if the CBR of the resource pool is less than a threshold, the WTRU may use an offset Δ_QoS. QoS Otherwise, if the CBR of the resource pool is greater than the threshold, the WTRU may not use the offset Δ QoS This approach can be used to reduce congestion in the resource pool.

[0107] In one example, when the WTRU does not receive a measurement report and / or indication from another WTRU, the WTRU may perform power adjustment. For example, the WTRU may not receive a SL-PRS measurement report from the Rx WTRU. The WTRU may increase its transmit power by Δ QoS, which may be a function of the QoS of the location service. The SL-RSRP threshold may be (pre-)configured as a function of the QoS of the location service. The WTRU may also determine whether to use a power offset (Δ QoS Specifically, if the CBR of a resource pool is less than a threshold, the WTRU may apply a power offset Δ QoS Otherwise, the WTRU may not apply a power offset Δ QoS .

[0108] In another example, the WTRU may perform power adjustment when the WTRU changes its coverage state (e.g., the WTRU changes from InC to OoC or the WTRU changes from OoC to InC). In another example, the WTRU may perform power adjustment when the WTRU changes its RRC state (e.g., the WTRU changes from RRC connected to idle / inactive or from idle / inactive to connected). In a further example, the WTRU may perform power adjustment when the WTRU enables / disables SL-PRS reception / indication or when the CBR is greater than / less than a threshold. The WTRU may perform power adjustment when the WTRU changes multiplexing of SL-PRS transmissions with other transmissions (e.g., from another WTRU) or when the number of SL-PRS transmissions in a period is greater than / less than a threshold.

[0109] In certain embodiments, the WTRU may determine the transmit power of one channel based on the transmission of another channel. In one solution, the WTRU may be (pre)configured with two different sets of parameters for two different channels (e.g., PSCCH / PSSCH and SL-PRS). The WTRU may calculate the transmission of the two channels independently. However, the WTRU may adjust the transmit power of one channel / signal based on the transmit power of another channel / signal.

[0110] In another example, the WTRU may adjust the transmit power of the PSCCH / PSSCH based on the transmit power of the SL-PRS. Specifically, the WTRU may adjust the transmit power of the PSCCH / PSSCH by increasing or decreasing the transmit power of the PSCCH / PSSCH so that the energy per resource element (EPRE) gap between the two channels is less than a threshold. The threshold may be fixed or (pre-)configured, which may be a function of the QoS of the positioning service.

[0111] As a further example, the WTRU may adjust the transmit power of the SL-PRS based on the transmit power of the PSCCH / PSSCH. Specifically, the WTRU may adjust the transmit power of the SL-PRS by increasing or decreasing the transmit power of the SL-PRS so that the EPRE gap between the two channels is less than a threshold. The threshold may be fixed or (pre-)configured, which may be a function of the QoS of the positioning service.

[0112] For additional embodiments, the WTRU may determine the transmit power of the SL-PRS based on whether the SL-PRS is multiplexed with data. For example, for SL-PRS transmission, the WTRU may multiplex the SL-PRS with sidelink data. The WTRU may determine the transmit power of the SL-PRS and / or sidelink data based on one or a combination of: (i) one or more power control parameters (pre-)configured for sidelink data communication; or (ii) one or more power control parameters (pre-)configured for SL-PRS transmission.

[0113] In one solution, the WTRU may determine the transmit power of the SL-PRS based on one or more power control parameters (pre-)configured for the sidelink data communication. Specifically, the WTRU may determine the transmit power of the SL-PRS based on the transmit power of the sidelink data. The WTRU may perform power boosting (e.g., increase the transmit power of the SL-PRS) for the SL-PRS. For example, the WTRU may first determine the transmit power of the sidelink data. Then, the WTRU may boost the transmit power of the SL-PRS by X dB compared to the sidelink data communication.

[0114] In another solution, the WTRU may determine the transmit power of the SL-PRS based on one or more power control parameters of both the SL-PRS and the sidelink data communication. Specifically, in the OLPC formula for determining the transmit power of the WTRU, the WTRU may use one or more transmit power parameters of the SL-PRS and one or more transmit power parameters of the sidelink data.

[0115] In another example, for SL-PRS transmission, the WTRU may multiplex the SL-PRS with the sidelink data. The WTRU may determine the transmit power of the SL-PRS and / or the sidelink data based on one or any combination of the power control parameters (pre-)configured for the sidelink data communication and the power control parameters (pre-)configured for the SL-PRS transmission. In one solution, the WTRU may determine the transmit power of the SL-PRS based on one or more power control parameters (pre-)configured for the sidelink data communication. Specifically, the WTRU may determine the transmit power of the SL-PRS based on the transmit power of the sidelink data. The WTRU may perform power boosting (e.g., increase the transmit power of the SL-PRS) for the SL-PRS. For example, the WTRU may first determine the transmit power of the sidelink data. Then, the WTRU may boost the transmit power of the SL-PRS by X dB compared to the sidelink data communication. In another solution, the WTRU may determine the transmit power of the SL-PRS based on one or more power control parameters for both the SL-PRS and the sidelink data communication. Specifically, in the OLPC formula for determining the transmit power of the WTRU, the WTRU may use one or more transmit power parameters of the SL-PRS and one or more transmit power parameters of the sidelink data.

[0116] In other embodiments, the WTRU may determine its transmit power based on the received power of the peer WTRU. In one solution, the WTRU may determine its transmit power (e.g., of the SL-PRS) based on the received power (e.g., of the SL-PRS) from the peer WTRU. Specifically, the WTRU may determine the nominal transmit power (e.g., target received power P) for the OLPC based on the received power from the peer WTRU. o ) value. This method can be used to support RTT positioning methods, in which the SL-PRS transmit and receive powers can be similar to achieve optimal positioning accuracy.

[0117] In another example, the WTRU may receive a SL-PRS from a peer WTRU during a positioning session. The WTRU may send a SL-PRS to a peer WTRU. In another example, the peer WTRU may be one of a group of WTRUs formed for positioning purposes (e.g., performing SL-TDOA, SL-AoA, SL-AoD). In one example, the peer WTRU may have location management function (LMF) functionality.

[0118] In yet another example, the WTRU may determine the path loss RS via configuration by the network / peer WTRU (e.g., the peer WTRU indicates the index of the SL-PRS resource to be used as the path loss RS). Using the path loss RS, the WTRU may determine the path loss or determine the transmit power based on the path loss measurement. In another example, the WTRU may measure the path loss RS and report the measurement result to the network / peer WTRU / WTRU that sent the path loss RS.

[0119] In some cases, the WTRU may determine to initiate OLPC if at least one of the following conditions is met: (1) the WTRU is configured by the network (e.g., gNB, LMF) or the target / anchor / peer WTRU to perform OLPC before SL-PRS is sent, and the WTRU receives a request to perform OLPC from the peer WTRU / network; (2) the measurement result changes (e.g., the change in the measurement result of the path loss RS (e.g., RSRP, RSRPP) is higher than a pre-configured threshold, where the change occurs between the last time the path loss RS was measured and the current time of measurement); or (3) a positioning method is used (e.g., if an RTT-based positioning method is configured, the WTRU may initiate OLPC).

[0120] In accordance with some embodiments, the WTRU may determine the sidelink path loss. In one solution, the WTRU may determine the SL path loss for use in the OLPC formula. The WTRU may determine the SL path loss based on measurement reports from peer WTRUs during the discovery process. Specifically, the WTRU may calculate the SL path loss based on the received power of the worst WTRU in the sidelink positioning group. The WTRU may receive measurement reports of received power during the discovery process to select a set of WTRUs in the sidelink positioning group.

[0121] In another example, the WTRU may determine the SL path loss for OLPC based on sidelink positioning measurement reports (e.g., SL-RSRP measurement reports) from peer WTRUs. Specifically, the WTRU may receive SL-RSRP measurements on SL-PRS transmissions. The WTRU may then determine the SL path loss based on the reported SL-RSRP measurements. In one method, the WTRU may use the reported minimum SL-RSRP to derive the SL path loss for SL-PRS transmissions. If the WTRU does not receive one or more SL-RSRP measurements from one or more WTRUs, the WTRU may use the maximum allowed transmit power. If one or more reported SL-RSRPs from one or more WTRUs are less than a (pre-)configured threshold, the WTRU may use the maximum allowed transmit power.

[0122] In another example, the WTRU may determine the SL path loss based on the measurement report of the reference WTRU / TRP. The WTRU may determine the reference WTRU based on the configuration from the network / peer WTRU (e.g., the reference WTRU may be indicated in the configuration). If the WTRU performs a group-based positioning method (e.g., SL-TDOA, SL-AoA), the WTRU may determine the reference WTRU in the group. The WTRU may send a path loss RS (e.g., SL-PRS) to the reference WTRU. The WTRU may determine the SL path loss based on the measurement report from the reference WTRU. In one example, the WTRU may determine the path loss based on the SL RS (e.g., SL-PRS, path loss RS) sent from the reference WTRU. The WTRU may receive configuration information (e.g., via unicast / multicast / broadcast) regarding which RS to monitor from the reference WTRU or regarding the reference WTRU ID for path loss determination.

[0123] In another example, the WTRU may determine a reference WTRU / RS for path loss determination based on at least one of the following conditions:

[0124] (i) The WTRU receives an indication / configuration from the network / WTRU regarding a reference WTRU or reference RS for path loss determination; (ii) The measurement result of the reference RS (e.g., SL-RSRP) is above / below a threshold; (iii) The channel condition (e.g., LOS indicator) is above a threshold; and (iv) Positioning method: For example, for RTT, the WTRU may determine that the peer WTRU is the reference WTRU. In another example, for SL-TDOA, the WTRU may determine the reference WTRU based on the configuration / indication from the network / peer WTRU / WTRU initiating the positioning session / WTRU with LMF capability.

[0125] According to various embodiments, the WTRU may determine the transmit power before having the SL path loss and / or DL ​​path loss information. In one approach, when the SL path loss is not available, the WTRU may use the DL path loss in the OLPC formula. In another approach, when the SL path loss is not available, the WTRU may use the maximum allowed transmit power. In another approach, when the SL path loss is not available, the WTRU may use a (pre-)configured default transmit power.

[0126] For embodiments where the WTRU determines the transmit power scheme based on the positioning method, in one solution, the WTRU (e.g., anchor WTRU) may determine which power control scheme to use (e.g., which set of power control parameters and the values ​​associated with each parameter) based on one or any combination of the positioning methods. For example, the WTRU may use OLPC for timing-based positioning methods (such as RTT, SL-TDOA). The WTRU may use fixed transmit power for angle-based positioning methods (such as AOD).

[0127] In some embodiments, a WTRU may request another WTRU to report the SL-RSP for its transmission. In one solution, a WTRU (e.g., a target WTRU) may request another WTRU (e.g., an anchor WTRU in a unicast link) to perform SL-RSRP measurements and report the measurement results. The WTRU may request which type of sidelink transmission may be used to measure SL-RSRP, which may include sidelink data transmissions, SL-PRS transmissions, or one of sidelink data transmissions and SL-PRS transmissions, or any combination thereof.

[0128] Based on the reported SL-RSRP from the peer WTRU (e.g., the recipient of the request), the WTRU may then derive the SL path loss in the unicast link between the two WTRUs. As used herein, "SL path loss derived from sidelink data" may describe the case where the SL path loss is derived from the SL-RSRP measured from the sidelink data transmission, and "SL path loss derived from SL-PRS" may describe the case where the SL path loss is derived from the SL-RSRP measured in the SL-PRS. The SL path loss derived from the SL-RSRP measured in both the SL-PRS and the sidelink data is equivalent to the SL path loss derived from the SL-PRS and the sidelink data transmission.

[0129] In one example, the WTRU may determine to use the SL path loss derived from the sidelink data for the SL-PRS based on at least one of the following conditions:

[0130] - The WTRU receives an indication from the network / peer WTRU to use the same path loss between the sidelink data and the SL-PRS. Using the same path loss here may mean that the WTRU measures the same path loss RS for both the sidelink communication and the sidelink positioning.

[0131] - If time and / or frequency resources from a shared resource pool are granted for SL-PRS transmission, and resources for SL data communication are granted from the same shared resource pool, the WTRU may determine to use the same path loss.

[0132] - SL-PRS is associated with SL RS (e.g. DMRS, CSI-RS) used for data communication. Examples of association may be spatial relationship (or in spatial QCL relationship), transmission from the same panel, same group (e.g. timing error group, phase error group).

[0133] For example, if the SL-PRS and DMRS in the SL channel are spatially correlated (eg, they are transmitted in the same direction), the WTRU may determine to use the same power for the SL-PRS as applied to the DMRS.

[0134] - The Rx WTRU is the same for SL data communication and SL positioning. For example, the WTRU sends SL-PRS or sidelink data to the same WTRU.

[0135] In one example, if a different resource pool than the data communication resource pool (e.g., a resource pool dedicated to positioning) is used for positioning, the WTRU may determine the path loss independently of data communication. In this case, the WTRU determines a path loss for SL positioning and another path loss for SL data transmission. The two resource pools may be different if their time and / or frequency resources do not overlap.

[0136] A WTRU (e.g., a target WTRU) may request a peer WTRU (e.g., an anchor WTRU) which type of SL transmission to use to measure SL-RSRP based on the SL-PRS configuration and / or the availability of SL-PRS resources. For example, if the WTRU does not have a SL-PRS configuration and / or SL-PRS resources are not available, the WTRU may request the peer WTRU to measure SL-RSRP based on sidelink communications. Alternatively, if the SL-PRS configuration and / or SL-PRS resources are available, the WTRU may request the peer WTRU to measure SL-RSRP based on the SL-PRS.

[0137] A WTRU (e.g., a target WTRU) may request a peer WTRU (e.g., an anchor WTRU) which type of SL transmission to use to measure SL-RSRP based on the type of resource pool (pre-)configured for SL-PRS transmission. For example, if SL-PRS is (pre-)configured to be transmitted in a shared resource pool, the WTRU may request the peer WTRU to measure SL-RSRP in both SL-PRS and sidelink data transmissions.

[0138] In one solution, the Rx WTRU may determine which sidelink transmissions to use for measuring SL-RSRP based on one or any combination of the following: indication from the Tx WTRU; SL-PRS configuration and / or availability of SL PRS transmissions; frequency of SL-PRS transmissions; and type of resource pool.

[0139] Regarding the availability of SL-PRS configuration and / or SL-PRS transmission, if SL-PRS configuration and / or SL-PRS transmission is not available, the WTRU may measure SL-RSRP in the sidelink data transmission. If SL-PRS is available, the WTRU may measure SL-RSRP in the SL-PRS transmission.

[0140] Regarding the frequency of SL-PRS transmission, if the number of SL-PRS resources within the measurement window is greater than a threshold, the WTRU may measure SL-RSRP in the SL-PRS. Otherwise, the WTRU may use sidelink data communication to measure SL-RSRP.

[0141] Regarding the type of resource pool (pre)configured for SL-PRS transmission, if the SL-PRS is (pre)configured to be transmitted in a shared resource pool, the WTRU may measure the SL-RSRP using the SL-PRS and / or the sidelink data transmission. In one example, the WTRU may measure the SL-RSRP using only the SL-PRS. In another example, the WTRU may measure the SL-RSRP using only the sidelink data transmission. In yet another example, the WTRU may measure the SL-RSRP using both the sidelink data transmission and the SL-PRS transmission.

[0142] For example, if the SL-PRS is (pre)configured to be transmitted in a dedicated resource pool, the WTRU may then measure each SL-RSRP individually. Specifically, the WTRU may measure the SL-RSRP using the SL-PRS in the dedicated resource pool for the SL-PRS. The WTRU may measure the SL-RSRP using the sidelink data transmission using the sidelink data resource pool.

[0143] In another example, when a SL-PRS is transmitted in a shared resource pool, the Rx WTRU may measure the SL-RSRP in both the SL-PRS and the sidelink communication. The Rx WTRU may first determine whether the transmission is from the expected WTRU (e.g., using the link ID, source ID, and / or destination ID indicated in the SCI), and then it filters these transmissions to derive the SL-RSRP. In another solution, the WTRU may measure the SL-RSRP based on the SL-PRS transmission. Specifically, the WTRU may first determine whether the transmission is from the expected WTRU (e.g., using the link ID, source ID, and / or destination ID indicated in the SCI). The WTRU may then determine whether the transmission includes the SL-PRS (e.g., based on the indication in the SCI). The WTRU may then filter these transmissions with the SL-PRS from the same WTRU to calculate the SL-RSRP.

[0144] In another example, the Rx WTRU may determine which SL-RSRP to report to the Tx WTRU. In one solution, the WTRU may report the SL-RSRP measured in the SL-PRS (if available); otherwise, it may report the SL-RSRP measured in the sidelink data transmission. In another solution, the WTRU may report both the SL-RSRP measured in the SL-PRS and the SL-RSRP measured in the sidelink data transmission.

[0145] In another example, the WTRU determines which SL path loss to use to calculate its SL-PRS transmit power. A WTRU (e.g., an anchor WTRU) may determine which SL path loss to use to calculate its SL-PRS transmit power based on one or any combination of the following: a pre-configured or configured priority, the availability of each SL path loss; or by determining a default SL path loss reference.

[0146] With respect to (pre-)configured and / or (pre-)defined priorities, the WTRU may prioritize the use of the SL path loss derived from the SL-PRS transmission (when available).

[0147] Regarding the availability of each SL path loss, the WTRU may always use the SL path loss derived from the SL-PRS transmission if available. When the SL path loss derived from the SL-PRS is not available, the WTRU may use the SL path loss derived from the sidelink data transmission. Alternatively, if the SL path loss derived from the SL-PRS is not available, the WTRU may use a fixed transmit power.

[0148] If the WTRU determines that SL path loss (e.g., SL path loss reference signal) is not available, the WTRU may determine to use a default SL path loss reference (e.g., DL RS) preset or configured by the network / peer WTRU (e.g., SSB).

[0149] In another approach, when one or both SL path losses are not available, the WTRU (e.g., the anchor WTRU) may determine to change its power control scheme (e.g., which set of power control parameters and values ​​associated with each parameter to use in Tx power calculations, whether to use OLPC or CLPC, whether to use fixed power or variable power, etc.). For example, if both SL and DL path losses are (pre-)configured, the WTRU may use only the DL path loss for OLPC when one or both SL path losses are not available. Alternatively, if the SL path loss is (pre-)configured for OLPC, the WTRU may use a fixed transmit power when one or both of the SL path losses are not available. In one example, the WTRU may use a fixed transmit power when the SL path loss derived from the SL-PRS is not available. In another example, the WTRU may use a fixed transmit power when both the SL path loss derived from the SL-PRS and the SL path loss derived from the sidelink data are not available.

[0150] A WTRU (e.g., an anchor WTRU) may determine which power control scheme (e.g., which set of power control parameters and the values ​​associated with each parameter) to use for multicast SL-PRS transmission based on one or any combination of the following: pre-configuration, DL path loss, a set of available SL path losses from the WTRU group, QoS of the positioning service, and the scope of the positioning group.

[0151] Regarding the (pre-)configuration option, the WTRU may be (pre-)configured with a fixed transmission level for the multicast SL-PRS. The WTRU may then send the multicast SL-PRS according to the (pre-)configured level.

[0152] Regarding DL path loss, for multicast SL-PRS transmission, the WTRU may use the DL path loss to calculate the OLPC transmit power based on the DL path loss alone.

[0153] With respect to the set of available SL path losses from the WTRU group, the WTRU may be (pre-)configured to use the SL path loss for OLPC. The WTRU may request one or more WTRUs to report SL-RSRP to derive the SL path loss. The WTRU may then determine the transmit power using OLPC based on a function of the available SL path losses from the WTRU group. Specifically, the WTRU may use the minimum SL path loss, the maximum SL path loss, or the average SL path loss to derive the transmit power from the OLPC formula.

[0154] Regarding the QoS of the positioning service (e.g., positioning accuracy), the WTRU may be (pre-)configured with multiple levels of transmit power for the multicast SL-PRS. The WTRU may then determine at which power level to transmit based on the positioning accuracy requirement.

[0155] With respect to the range of the positioning group, the WTRU may be (pre-)configured with its transmit power as a function of the range of the positioning group (e.g., the maximum distance between one SL-PRS sender and one SL-PRS receiver, e.g., the maximum distance between an anchor WTRU and a target WTRU). The WTRU may then determine its transmit power based on the range of the group.

[0156] A WTRU (e.g., an anchor WTRU) may determine which power control scheme (e.g., which set of power control parameters and the values ​​associated with each parameter) to use for broadcast SL-PRS transmission based on one or any combination of the following: pre-configuration, DL path loss, a set of available SL path losses from the WTRU group, the QoS of the positioning service, and the scope of the positioning service.

[0157] Regarding the (pre-)configuration option, the WTRU may be (pre-)configured with a fixed transmission level for broadcast SL-PRS. The WTRU may then transmit the broadcast SL-PRS according to the (pre-)configured level.

[0158] Regarding the DL path loss parameter, for broadcast SL-PRS transmissions, the WTRU may use the DL path loss to calculate the OLPC transmit power based on the DL path loss alone.

[0159] Regarding QoS (e.g., positioning accuracy) parameters for positioning services, the WTRU may be (pre-)configured with multiple levels of transmit power for multicast SL-PRS. The WTRU may then determine at which power level to transmit based on the positioning accuracy requirement. Specifically, the WTRU may use a low transmit power for positioning services with low accuracy requirements. Conversely, the WTRU may use a high transmit power for positioning services with high accuracy requirements. The QoS requirements for positioning services may be indicated from another WTRU, from the network (e.g., LMF, gNB), or selected by the WTRU itself.

[0160] Regarding the range of the positioning service, the WTRU (eg, RSU) may be (pre-)configured with a transmit power level as a function of its positioning service range. The WTRU may then determine at which power level to transmit based on the range of the positioning service.

[0161] In one solution, a WTRU (e.g., an anchor WTRU) may determine whether to use OLPC based on one or any combination of: positioning method; availability of SL or DL ​​path loss; RS path loss; power used by peer WTRUs; measurements; or received measurement reports.

[0162] Regarding positioning methods, the WTRU may use OLPC for timing based methods (such as SL-TDOA and RTT). The WTRU may not use OLPC for angle based positioning methods (such as AOD, AOA).

[0163] Regarding the availability options of SL and / or DL ​​path loss, if the WTRU is (pre)configured to use both SL and DL path loss, the WTRU may not use OLPC when SL and / or DL ​​path loss is not available. When SL and / or DL ​​path loss is not available, the WTRU may be (pre)configured with a fixed transmit power. For example, the WTRU may be (pre)configured to use SL path loss, and in one method, when SL path loss is available, the WTRU may determine to use OLPC. In another method, when the SL path loss measured in the SL-PRS is available, the WTRU may determine to use OLPC. Otherwise, when the SL path loss measured in the SL-PRS is not available, the WTRU may not use OLPC. An example of the availability of path loss is as follows: The WTRU may be configured to use RS (e.g., DL-RS, SL-RS) for path loss measurement. The WTRU may measure the path loss RS, and the measurement result (e.g., RSRP) may be below a threshold. In this case, the WTRU may determine that the path loss RS is not available. In another example, the WTRU may not receive path loss measurements from a peer WTRU / network.

[0164] In one example, the WTRU may determine the power level of the OLPC using a reference RS (e.g., a path loss reference RS) and apply the determined power level to the RS (e.g., a power target RS). The WTRU may determine the power / power level (e.g., in Watts, dB, dBm) determined for the power target RS to be applied to the RS associated with the power target RS. The power level may be determined based on a reference power (e.g., a transmit power used at the Tx panel of the WTRU). Examples of associations between RSs are as follows: one or more RSs are spatially associated (e.g., two RSs transmit in similar directions, e.g., within the range of AoD, or in a QCL (quasi co-location) relationship (e.g., two RSs experience similar Doppler frequency / offset, similar channel environment), one or more RSs are associated with the same resource set / TRP / PRS ID / frequency layer / group (e.g., timing error group, phase error group, group in multicast, group determined by target WTRU), power target WTRU receives an indication from the network / WTRU to apply a power level to the indicated RS group / set / subset. In another example, the WTRU may determine to apply the same power / power level to the RS associated with the power target RS based on a positioning method. For example, if the WTRU uses an angle-based positioning method (e.g., SL-AoA), the WTRU may determine to apply the same power / power level to the RS associated with the power target RS.

[0165] In an example embodiment, a WTRU may determine to use a power level / power used by a peer WTRU. For example, if the WTRU is configured with an RTT-based positioning method (e.g., two WTRUs send SL-PRS to each other to measure the round trip time), one WTRU (e.g., an anchor WTRU) may indicate its power level / power (e.g., determined according to OLPC) to a peer WTRU (e.g., a target WTRU). For example, the target WTRU may receive an indication of the power / power level from the anchor WTRU and use the power / power level to adjust its own transmit power.

[0166] In another example embodiment, the WTRU may determine to measure the path loss RS and determine the path loss based on the measurement, or receive a measurement report from a peer WTRU and determine the path loss based on the report. The WTRU may determine one of the above actions whether the WTRU is the first WTRU to transmit / receive in the RTT positioning method (e.g., two WTRUs transmit SL-PRS to each other). For example, if the WTRU transmits the SL-PRS first, the WTRU may determine the path loss based on the measurement report returned from the peer WTRU (e.g., RSRP of the transmitted SL-PRS, RSRP of the path loss reference). Alternatively, if the WTRU receives the SL-PRS first, the WTRU determines the path loss based on the path loss reference RS (e.g., SL-PRS). In another example, the WTRU performing the RTT positioning method may determine the path loss based on the configured path loss RS (e.g., SSB).

[0167] For various embodiments, the validity of the power / power level determined by OLPC is now described. In one example, the WTRU may determine that the power / power level determined by OLPC is valid during a positioning session (e.g., the duration during which the WTRU performs positioning and ends when a termination requirement (e.g., the WTRU reports its location) is met).

[0168] In another example, if the power / power level determined by the OLPC is determined by a concurrent SL data communication session (eg, a data communication session running in parallel with a positioning session), then the power / power level may be considered valid.

[0169] In some embodiments, the power / power level determined by the WTRU may be associated with a timer. For example, if the WTRU determines that the timer of the current power / power level has expired, the WTRU may start / restart the OLPC process (e.g., determine the power / power level based on the path loss RS).

[0170] If the WTRU determines that the same path loss is used for both SL data and SL-PRS transmissions, the WTRU may determine the validity based on the criteria defined for data communication or positioning. For example, if the path loss associated with the RS used for positioning and SL data communication becomes invalid based on the criteria used for data communication, the WTRU may determine that the path loss is invalid for positioning.

[0171] In other example embodiments, the WTRU may determine whether to adjust its transmit power for congestion control. In one solution, a WTRU (e.g., an anchor WTRU) may determine whether to adjust its transmit power during a measurement gap and / or measurement window for congestion control based on the positioning method. For example, the WTRU may adjust its transmit power for timing-based positioning methods (such as SL-TDOA, RTT). The WTRU may fix its transmit power (e.g., apply the same transmit power to a group / subset of SL-PRS) for angle-based positioning methods (such as AoD, AoA) and / or any positioning method that requires measuring RSRP / RSRP per path.

[0172] In one solution, a WTRU (e.g., an anchor WTRU) may determine whether to adjust its transmit power for congestion control during a measurement gap and / or measurement window based on whether the WTRU indicates its transmit power in a transmission associated with a SL-PRS (e.g., in an SCI). For example, if the WTRU indicates its transmit power in a transmission associated with a SL-PRS, the WTRU may adjust its transmit power for congestion control. Otherwise, if the WTRU does not indicate its transmit power in a transmission associated with a SL-PRS, the WTRU may fix its transmit power for the measurement gap and / or measurement window.

[0173] In one solution, a WTRU (eg, an anchor WTRU) may determine whether to stop OLPC. Specifically, the WTRU may fix its transmit power based on whether the WTRU has reached its maximum (pre-)configured transmit power.

[0174] The WTRU may also fix its transmit power based on whether the WTRU changes to another positioning method. For example, the WTRU may be instructed to change from a timing-based positioning method to an angle-based positioning method, the WTRU may then stop using its OLPC and may then use a fixed transmit power.

[0175] In yet another example, the WTRU may stop OLPC and the WTRU may determine to use the transmit power (e.g., in dB, Watts, dBm) determined for the previous / last transmit opportunity. Alternatively, the WTRU may determine to initiate OLPC for a different RS (e.g., not to use the RS if OLPC is not being performed).

[0176] In another example, the WTRU may use a transmit power pre-configured by the network (e.g., gNB, LMF) or the WTRU. The transmit power may be a preset value at the WTRU.

[0177] In another example, the measurement result (e.g., RSRP, AoA, AoD) of the path loss reference RS (e.g., SL CSI RS, SSB, DL RS) is lower or higher than a threshold, and the WTRU determines to stop OLPC. In another example, the quality indicator / range of the measurement result of the path loss reference RS (e.g., the range of RSRP measurement results, the standard deviation / variance of RSRP measurement results) is higher / lower than a threshold, and the WTRU determines to stop OLPC. For example, if the WTRU determines that the path loss reference is unreliable (e.g., RSRP is lower than a threshold), the WTRU determines to stop OLPC. When the WTRU determines to stop OLPC, the WTRU may use a transmit power pre-configured by the network (e.g., gNB, LMF) or a peer WTRU, or a preset value at the WTRU.

[0178] In another example, the WTRU may determine that the OLPC time period has expired, wherein when the WTRU starts OLPC, the WTRU starts a timer. If the WTRU determines that the OLPC timer has expired, the WTRU stops OLPC.

[0179] In another example, the WTRU may determine that a time window associated with OLPC has passed. In one example, the WTRU may be configured with a start time / end time / duration of a time window during which the WTRU may perform OLPC. The start time / end time may be expressed in absolute time / relative time, and the symbol / time slot / frame index and duration may be expressed in number of symbols / number of time slots / number of frames or number of seconds.

[0180] The WTRU may determine that the spatial relationship between the reference RS (eg, DL / SL RS) and the OLPC-applied RS is invalid (eg, spatial relationship). The WTRU may receive an indication from the network that the spatial relationship between the reference and OLPC-applied RS is invalid, and the WTRU stops OLPC.

[0181] In some embodiments, the WTRU may determine to use a fixed transmit power. In one solution, a WTRU (e.g., an anchor WTRU) may determine to fix its transmit power for the SL-PRS. The WTRU may then determine its transmit power based on one or any combination of the following: (pre) configuration; QoS requirements of the positioning service, or an indication from another WTRU. For example, the WTRU may be (pre) configured with multiple transmit levels, where each transmit level may be associated with a QoS requirement of the positioning service (e.g., priority, latency, reliability, accuracy, positioning range). For example, the WTRU may use a high transmit power for positioning services with high accuracy requirements and / or a lower transmit power for positioning services with less stringent accuracy requirements. The WTRU may use a high transmit power for a high positioning range requirement, or alternatively, the WTRU may use a low transmit power for a low positioning range requirement. In another example, when the target WTRU may be a SL-PRS receiver, it may then indicate the expected transmit power of the anchor WTRU through signaling.

[0182] A WTRU (e.g., an anchor WTRU) may determine its fixed transmit power based on one or more parameters calculated / derived prior to a measurement gap and / or measurement window. Specifically, the WTRU may derive DL path loss, SL path loss, and CBR prior to the measurement window and / or measurement gap. The WTRU may then calculate the transmit power of its SL-PRS using one or more of these parameters using the OLPC formula. The WTRU may then maintain its transmit power during the measurement gap and / or measurement window. The WTRU may determine the measurement gap parameters via configuration from the network or a peer WTRU.

[0183] In another example, a WTRU (e.g., an anchor WTRU) may indicate its transmit power to a peer WTRU (e.g., a target WTRU), which may be used to support the peer WTRU in determining the link quality between the two WTRUs. In one approach, the WTRU may indicate its transmit power in each transmission associated with the SL-PRS (e.g., in the SCI). In another approach, the WTRU may indicate the transmit power of its SL-PRS during a measurement window. The WTRU may implicitly / explicitly indicate a measurement gap and / or measurement window to the peer WTRU. The WTRU may then fix its transmit power / power level during the measurement gap and / or measurement window. The WTRU may then indicate its transmit power using, for example, MAC CE, PC5 RRC, and / or Sidelink Positioning Protocol (SLPP).

[0184] In another example, a WTRU (e.g., an anchor WTRU) may determine whether to indicate its transmit power to another WTRU (e.g., a target WTRU) based on whether the WTRU is a recipient of SL-PRS measurement results. Specifically, if the WTRU is not a recipient of the SL-PRS measurement report, the WTRU may indicate its transmit power to the peer WTRU. Otherwise, if the WTRU is a recipient of the SL-PRS measurement report, the WTRU may not indicate its transmit power to the peer WTRU.

[0185] For another example, a WTRU (e.g., an anchor WTRU) may indicate its transmit power to the network (e.g., LMF) to support the network in calculating the link between the two WTRUs. In another method, a WTRU may indicate its transmit power to a peer WTRU (e.g., a target WTRU). A WTRU may determine whether to indicate its transmit power to the network (e.g., LMF) and / or another WTRU based on one or any combination of the following: whether the positioning method is WTRU-assisted or WTRU-based, or the coverage status of the WTRU.

[0186] For example, for WTRU-based positioning methods, the WTRU may indicate the transmit power to a peer WTRU (eg, target WTRU).For WTRU-assisted positioning methods, the WTRU may indicate its transmit power to the network (eg, LMF).

[0187] In one case, if the WTRU is out of coverage, the WTRU may report its transmit power to a peer WTRU. The peer WTRU may then determine whether to report the indicated power to the network (e.g., LMF) based on whether it is performing a WTRU-assisted positioning method or a WTRU-based positioning method. Specifically, if the WTRU is performing a WTRU-assisted positioning method, the WTRU may report the indicated transmit power to the network; otherwise, if it is a WTRU-based positioning method, the WTRU may not report the indicated transmit power to the network.

[0188] An implementation scheme for performing closed loop power control (CLPC) on the sidelink is now described. In one example, the WTRU may indicate information and request feedback of the SL-PRS receive power. For example, the WTRU may perform SL-PRS transmission. The WTRU may implicitly / explicitly request the receiving WTRU to feedback the SL-PRS reception quality or receive power. The WTRU may also indicate information used to help the RxWTRU perform feedback (for example, the Tx WTRU may implicitly indicate the target SL-RSRP or SL-RSRP receive threshold in its transmission (for example, in the SCI, MAC CE and / or PC5 RRC)). Specifically, the WTRU may indicate and / or request the Rx WTRU to feedback one or any combination of the following: whether to feedback the SL-PRS receive power; whether the Rx WTRU needs additional SL-PRS transmission; whether the receive power of the SL-PRS is less than / greater than a threshold; whether the receive power of the SL-PRS is less than a threshold; whether the receive power of the SL-PRS is greater than a threshold; and / or the receive level of the SL-PRS.

[0189] In one example, the Tx WTRU may indicate to the Rx WTRU whether to feedback the SL-PRS received power. If the Tx WTRU enables feedback of the SL-PRS received power, the Tx WTRU may expect to receive feedback from the Rx WTRU. Otherwise, if the Tx WTRU disables feedback of the SL-PRS received power, the Tx WTRU may not expect to receive feedback from the Rx WTRU.

[0190] In one example, the WTRU may indicate to the RX WTRU whether the Rx WTRU requires additional SL-PRS transmissions. For example, the Tx WTRU may request the Rx WTRU to provide feedback to itself whether the Rx WTRU requires more SL-PRS transmissions within a period of time. In one approach, the Tx WTRU may instruct / configure the Rx WTRU to perform minimum and / or maximum reception / measurements in N SL-PRS resources. In another approach, the Tx WTRU may (pre-)configure / instruct the Rx WTRU to perform minimum and / or maximum reception / measurements of N SL-PRS resources, where each SL-PRS resource should have a measured SL-RSRP greater than a threshold. The number of SL-PRS measurement resources and the threshold may be indicated to the WTRU and / or (pre-)configured (e.g., via a sidelink positioning configuration, and / or via a transmission associated with the SL-PRS). The WTRU (e.g., the Rx WTRU) may then determine whether it has been indicated that it has measured enough resources for the SL-PRS measurement report. Specifically, if the measured number of resources with SL-RSRP is less than a threshold, the WTRU may request the Tx WTRU to perform additional SL-PRS transmission; otherwise, the WTRU may not request the Tx WTRU to perform additional SL-PRS transmission.

[0191] In one example, the Tx WTRU may indicate to the Rx WTRU whether the received power of the SL-PRS is less than / greater than a threshold (e.g., an ACK / NACK based method). For example, the Tx WTRU may request the Rx WTRU to feedback to the Tx WTRU whether the received power of the SL-PRS is greater than or less than a threshold. The threshold may be (pre-)configured or may be indicated to the Rx WTRU by the Tx WTRU.

[0192] In another example, the Tx WTRU may indicate to the Rx WTRU whether the received power of the SL-PRS is less than a threshold (NACK-based method). For example, the Tx WTRU may request the Rx WTRU to feedback to the Tx WTRU whether the received power of the SL-PRS is less than a threshold. The threshold may be (pre)configured or may be indicated to the WTRU. If the received power of the SL-PRS is less than the threshold, the Rx WTRU may provide feedback to the Tx WTRU; otherwise, the Rx WTRU may not feedback the received power of the SL-PRS.

[0193] In some cases, the Tx WTRU may indicate to the Rx WTRU whether the received power of the SL-PRS is greater than a threshold (ACK-based method). For example, the Tx WTRU may request the Rx WTRU to feedback to the Tx WTRU whether the received power of the SL-PRS is greater than a threshold. The threshold may be (pre-)configured or indicated to the WTRU. If the received power of the SL-PRS is greater than the threshold, the Rx WTRU may provide feedback to the Tx WTRU; otherwise, the Rx WTRU may not feedback the received power of the SL-PRS.

[0194] In one example, the WTRU may indicate the received level of the SL-PRS to the Rx WTRU. For example, the Tx WTRU may request the Rx WTRU to feedback the received power level of its SL-PRS. In one method, the Rx WTRU may be (pre-)configured with a table of SL-RSRPs, where each index in the table may be associated with a range of SL-RSRPs. The Rx WTRU may then indicate the received power level of the SL-PRS by indicating the index in the table.

[0195] In another example, the WTRU may indicate to the Rx WTRU what type of feedback to provide for the received power of the SL-PRS. The Tx WTRU may indicate to the Rx WTRU what type of feedback to provide for the received power of the SL-PRS (e.g., ACK based, NACK based, ACK / NACK based, received power level based). The Rx WTRU may then feedback the received power of the SL-PRS to the Tx WTRU based on the requested feedback type from the Tx WTRU.

[0196] For some embodiments, the WTRU may indicate the number of SL-PRS reception resources to the Rx WTRU. For example, the Tx WTRU may indicate the maximum / minimum number of SL-PRS to be measured in a time period. The Tx WTRU may expect the Rx WTRU to perform measurements in a number of resources that fall within the indicated range. The minimum / maximum number of SL-PRS resources to be measured may be determined based on the QoS of the positioning service, the CBR of the resource pool, the measurement reporting period, and / or the SL-PRS pattern.

[0197] In another example, the WTRU may indicate to the Rx WTRU the number of SL-PRS resources for which the SL-RSRP is greater than a threshold. For example, the Tx WTRU may indicate the minimum number of SL-PRS resources (e.g., N resources) measured in a period of time, where the received power of each SL-PRS is greater than an indicated / (pre-)configured threshold. The value of N may be determined based on the QoS of the positioning service, the CBR of the resource pool, the measurement reporting period, and / or the SL-PRS pattern.

[0198] The WTRU may also indicate to the Rx WTRU the QoS associated with the feedback of the SL-PRS received power. The QoS may include priority, latency, and / or reliability of the feedback message / signal.

[0199] In certain embodiments, the WTRU may use PSFCH, SCI, MAC CE, PC5 RRC and / or NAS (e.g., LPP) messages to feedback the received power of the SL-PRS to the Tx WTRU. The WTRU may use PSFCH to indicate whether it needs more SL-PRS reception resources to perform measurements. The WTRU may use PSFCH to indicate whether the received power is less than / greater than a threshold (e.g., ACK / NACK based method). The WTRU may use SCI (e.g., second stage SCI) and / or MAC CE to indicate the reception level of the SL-PRS. In one method, the WTRU may indicate the L3 filtered SL-RSRP of the SL-PRS measurement from a set of SL-PRS resources. In another method, the Rx WTRU may indicate multiple received L1 SL-RSRPs, where each SL-RSRP is associated with one SL-PRS resource.

[0200] In another example, the WTRU may determine resources for feeding back received power to the Tx WTRU. The WTRU (e.g., RxWTRU) may determine resources for feeding back received power to the Tx WTRU. The resources for feeding back the received power of the Tx WTRU may be determined based on the type of message used to feed back received power. In one example, if the WTRU uses PSFCH to feed back the received power of PSFCH. The WTRU may be (pre) configured with a mapping between SL-PRS reception and feedback. The WTRU may then determine which PSFCH resource is used for feedback based on the received SL-PRS resource. In another example, if the Rx WTRU uses SCI, MAC CE, PC5 RRC and / or NAS (e.g., LPP) messages to feed back the received power of SL-PRS, the resource may be indicated by the TxWTRU. In another method, the Rx WTRU may be (pre) configured with resources for performing transmission of feedback, which may be transmitted in a data channel (e.g., PSCCH / PSSCH).

[0201] In some cases, the Rx WTRU may determine the QoS of the feedback message. In this case, the Rx WTRU may use SCI, MAC CE, PC5 RRC and / or NAS (e.g., LPP) messages to feedback the received power to the Tx WTRU. The Rx WTRU may determine the QoS (e.g., priority, latency, reliability and / or minimum communication range) of the feedback message based on one or any combination of the following: (pre-)configured priority; QoS of the positioning service; QoS of the sidelink positioning measurement report; and / or implicit / explicit indication from another node.

[0202] In an example, the Rx WTRU may determine the QoS of the feedback message based on a pre-configured priority. For example, the Rx WTRU may be (pre-)configured with a priority (e.g., the highest priority) associated with the SL-PRS. The Rx WTRU may then perform sensing and resource allocation for the feedback based on the (pre-)configured priority. The Rx WTRU may then indicate the priority of the feedback in the transmission. The Rx WTRU may then implicitly / explicitly indicate the identity of the message used to feedback the received power of the SL-PRS.

[0203] In another example, the Rx WTRU may determine the QoS of the feedback message based on the QoS of the positioning service. For example, the priority of the feedback message may be equal to the priority of the positioning service. The Rx WTRU may then perform sensing and resource allocation for the feedback based on the (pre-)configured priority. The Rx WTRU may then indicate the priority of the feedback in the transmission.

[0204] For one embodiment, the Rx WTRU may determine the QoS of the feedback message based on the QoS of the sidelink positioning measurement report. For example, the priority of the feedback message may be equal to the priority of the sidelink measurement report message. The Rx WTRU may then perform sensing and resource allocation for the feedback based on the (pre-)configured priority and indicate the priority of the feedback in the transmission.

[0205] In some cases, the Rx WTRU may determine the QoS of the feedback message based on implicit / explicit indications from another node (eg, from a Tx WTRU).

[0206] In another example, the Rx WTRU may perform SL-PRS measurements. For example, the Rx WTRU may perform SL-PRS measurements to perform SL-PRS measurement reporting and / or to feed back the received power of the SL-PRS to another node. If the measured SL-RSRP of a SL-PRS measurement resource is greater than a threshold, the Rx WTRU may include the resource in the report. Otherwise, it may remove the measured resource from the report (e.g., the Rx WTRU may not include the resource in the filtering calculation and / or the Rx WTRU may not report the resource in the sidelink measurement report). During a specific period of time, the Rx WTRU may continue to perform measurements until it collects at least N resources with SL-RSRP greater than the threshold. The value of N and the SL-RSRP threshold may be indicated from another WTRU (e.g., the Tx WTRU of the SL-PRS).

[0207] For certain embodiments, the Tx WTRU may adjust its transmit power based on an indication from the Rx WTRU. In one approach, the Tx WTRU may adjust its transmit power based on ACK / NACK based feedback from the Rx WTRU on the SL-PRS receive power. Specifically, if the WTRU receives an ACK from the Rx WTRU, which may indicate that the receive power is greater than a threshold, the WTRU may maintain the same power or reduce the power offset. Otherwise, if the Tx WTRU receives a NACK from the Rx WTRU, which may indicate that the receive power is less than a threshold, the Tx WTRU may increase the power offset.

[0208] In another method, the Tx WTRU may adjust its transmit power based on NACK-based feedback from the Rx WTRU on the SL-PRS received power. Specifically, if the Tx WTRU does not receive feedback from the Rx WTRU, the Tx WTRU may maintain the same power; otherwise, if the Tx WTRU receives a NACK from the Rx WTRU, the Tx WTRU may increase the power offset, which NACK may be used to indicate that the received power is less than a threshold.

[0209] In one embodiment, the Tx WTRU may adjust its transmit power based on the ACK-based feedback on the SL-PRS receive power from the Rx WTRU. Specifically, if the Tx WTRU does not receive feedback from the Rx WTRU, the Tx WTRU may increase its transmit power; otherwise, if the WTRU receives ACK feedback from the Rx WTRU, the WTRU may maintain the same power, which ACK feedback may be used to indicate that the receive power is greater than the threshold.

[0210] In another example, the Tx WTRU may adjust its transmit power based on the reported SL-PRS power reception level from the Rx WTRU. Specifically, the Tx WTRU may determine to increase / decrease the power offset based on the reported power reception level from the Rx WTRU. The power offset may be determined based on the QoS of the location service and / or the CBR of the resource pool.

[0211] An implementation scheme of WTRU behavior in the case where the transmission reaches the (pre)configured maximum power of the WTRU is now described. In one solution, if the WTRU's transmit power reaches its maximum value and / or the number of SL-PRS transmissions reaches its maximum value, the WTRU may perform one of the following actions or any combination thereof. The following behavior may be performed based on implicit / explicit feedback from the Rx WTRU, which implicitly / explicitly indicates that the received power of the received SL-PRS is less than a threshold. In one method, the Tx WTRU may change the SL-PRS pattern (e.g., increase the comb size, reduce the bandwidth). In another method, the Tx WTRU may transmit an indication of the transmit power to another node (e.g., another WTRU or a gNB). In another method, the WTRU may change the resource pool. In yet another method, the WTRU may update the group sidelink positioning by removing the Rx WTRU from the group. For example, the Tx WTRU cannot further increase the Tx power (e.g., limited by the maximum Tx power) to increase the RSRP at the Rx WTRU to clear the threshold, e.g., the Rx WTRU moves too far. In this case, the Tx WTRU may decide to drop the Rx WTRU from the positioning group.

[0212] In the case where the Rx WTRU uses PSFCH to feedback the received SL-PRS, the Rx WTRU may determine the QoS (e.g., priority) of the feedback message based on one or any combination of the following: (pre-) configuration; the QoS (e.g., priority) of the SL-PRS; or the QoS (e.g., priority) of the SL-PRS measurement report.

[0213] In some scenarios, the WTRU may need to send and / or receive multiple PSFCHs, where the PSFCHs may be associated with SL-PRS feedback, inter-WTRU coordination (IUC) for conflict indication, and / or sidelink data. If the WTRU cannot send and / or receive all required PSFCHs at the same time, the WTRU may perform PSFCH prioritization. The WTRU may perform PSFCH prioritization based on one or any combination of the following: Pre-configuration. For example, the WTRU may be (pre-)configured to sequentially prioritize one type of PSFCH over another type of PSFCH. For example, the WTRU may be (pre-)configured to prioritize PSFCH for data transmission first, then the WTRU may prioritize PSFCH for IUC second, and finally, PSFCH has the lowest priority. The WTRU may then sequentially discard the PSFCH for SL-PRS first, then it may discard the PSFCH feedback for IUC, and finally, discard the PSFCH for communication last.

[0214] refer to Figure 2 and Figure 3 , another example implementation of a WTRU that performs open loop power control (OLPC) is described herein. Figure 2 An example OLPC method 200 for transmitting a sidelink positioning reference signal (SL-PRS) is shown. Figure 3 A corresponding signaling diagram 300 for OLPC transmission and feedback of SL-PRS between a Tx WTRU 310 and an Rx WTRU 320 is shown. In this example embodiment, the WTRU may determine whether to apply a power offset as a function of the QoS of the positioning service in an open loop power control (OLPC) formula for SL-PRS transmission and whether the reported SL-RSRP of the SL-PRS is less than a threshold. Specifically, the WTRU may perform the following process to determine the transmit power of one or more SL-PRSs.

[0215] like Figure 2As shown, method 200, a WTRU may be (pre)configured 205 with the following OLPC power control parameters: SL and DL path loss compensation (e.g., α and P0 for SL and DL); one or more SL-RSRP thresholds, each threshold being associated with a QoS (e.g., priority) of a positioning service; and one or more offsets for the OLPC formula, each offset being a function of the QoS (e.g., priority) of the positioning service, referred to as "delta_offset". At 210, the WTRU may be triggered to send one or more SL-PRSs with associated QoS / priority levels, for example, via network access stratum (NAS) signaling. Next, the WTRU performs SL-PRS transmission 215 using the (pre)configured OLPC based on the SL and DL path loss compensation for the associated priority. At step 220, the WTRU receives sidelink positioning measurement reports (including SL-RSRP) from one or more peer Rx WTRUs.

[0216] The WTRU compares 225 the received SL-RSRP to determine the power of the next SL-PRS transmission. If the reported SL-RSRP 230 is greater than the (pre-)configured SL-RSRP threshold for the associated QoS / priority, the WTRU uses the same OLPC formula and the SL and DL path loss compensation parameters to derive the transmit power of the next SL-PRS. Otherwise, at step 235, the WTRU increases the SL-PRS transmit power parameter by applying the (pre-)configured delta_offset based on the priority / QoS of the location service to the OLPC formula. At step 240, the WTRU transmits the next SL-PRS based on the power level derived at step 230 or 235. In some embodiments (not shown), if the Tx power reaches its maximum value, the WTRU may perform one or any of the following operations: change the SL-PRS pattern (e.g., increase the comb size); change the resource pool; and / or notify another node (e.g., a gNB or another WTRU).

[0217] Figure 3 Shows the corresponding Figure 2300 of the method 200 of FIG. 300. As shown, in a first step, the Tx WTRU 310 sends one or more SL-PRS 312 with associated QoS / priority levels to the Rx WTRU 320 based on the (pre-)configured OLPC formulas including the SL and / or DL ​​path loss parameters (α and P0). In a second step, the Rx WTRU 320 returns a SL-PRS measurement report 322 including an RSRP indication for the received SL-PRS. In a third step, the Tx WTRU 310 evaluates the received RSRP feedback to determine the transmit power of the next SL-PRS to be transmitted. If the received RSRP is greater than or equal to the (pre-)configured threshold associated with the QoS / priority, the Tx WTRU 310 will continue to use the original OLPC parameters to derive the power for transmitting additional SL-PRS 332. If the received RSRP is below the (pre-)configured RSRP threshold for the associated QoS / priority, the Tx WTRU 310 shall additionally apply a delta_offset according to the (pre-)configured delta_offset 350 for the corresponding priority level 352. One or more additional SL-PRS 332 may be sent by the Tx WTRU 310 at a power based on the previous determination.

[0218] An example implementation of a Tx WTRU performing closed loop power control (CLPC) is described herein. The Tx WTRU may perform CLPC for SL-PRS transmission and determine to adjust its SL-PRS transmit power based on the SL-RSRP threshold of the SL-PRS, the number of SL-PRS measurement resources, and the SL-PRS feedback from the receiving WTRU. Specifically, the Tx WTRU may perform the following process to determine the SL-PRS transmit power. First, the WTRU is (pre-)configured with the following parameters: the received SL-RSRP threshold of the SL-PRS and the number of SL-PRS measurement resources with a received SL-RSRP greater than the threshold, and an offset for each power adjustment step. Next, the Tx WTRU performs SL-PRS transmission and indicates the RSRP threshold to the Rx WTRU (e.g., in the SCI associated with the SL-PRS transmission) using the initial Tx power. The Tx WTRU then receives feedback from the Rx WTRU regarding the SL-PRS received power. Next, the Tx WTRU performs the following process for the new SL-PRS transmission: If the Rx WTRU indicates that the received SL-RSRP is less than the threshold, the Tx WTRU increases the power using the (pre-)configured offset. Otherwise, the Tx WTRU uses the same Tx power for the new SL-PRS transmission and sends one or more additional SL-PRS using the determined power.

[0219] An example implementation of an Rx WTRU performing closed loop power control (CLPC) is described herein. The Rx WTRU may perform CLPC of a SL-PRS. The Rx WTRU may determine whether to include the SL-PRS in a measurement report based on the received SL-RSRP of the received SL-PRS. In the event that the received SL-RSRP is less than a threshold, the Rx WTRU feeds back the SL-PRS received power to the Tx WTRU, indicating that the SL-RSRP is less than the threshold (e.g., using a one-bit indication of the PSFCH). Specifically, the Rx WTRU may perform the following process for the CLPC received by the SL-PRS. The WTRU may be (pre-)configured with the number of SL-PRS measurement resources for which the received SL-RSRP is greater than the threshold. The Rx WTRU receives a SL-PRS with an RSRP threshold (e.g., an index in an RSRP threshold table) from the Tx WTRU, the threshold being indicated in the associated SCI. If the SL-RSRP measured on the SL-PRS is less than the threshold, the Rx WTRU indicates this to the Tx WTRU (e.g., using a one-bit indication on the PSFCH). Otherwise, the Rx WTRU includes the SL-PRS resources in the measurement report until the number of measured SL-PRS resources with SL-RSRP greater than the SL-RSRP threshold in the SL-PRS resources is greater than the threshold. Finally, the WTRU performs a SL-PRS measurement report and sends it to the Tx WTRU.

[0220] Although the features and elements are described above in specific combinations, it will be understood by those of ordinary skill in the art that each feature or element may be used alone or in any combination with other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (sent via a wired or wireless connection) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media (such as built-in hard disks and removable disks), magneto-optical media, and optical media (such as CD-ROM disks and digital versatile disks (DVDs)). A processor associated with software may be used to implement a radio frequency transceiver for a WTRU, WTRU, terminal, base station, RNC, or any host computer.

Claims

1. A method for a wireless transmit receive unit (WTRU), the method comprising: receiving configuration information including open loop power control (OLPC) parameters for sidelink (SL) positioning reference signal (PRS) transmission, one or more delta power offsets as a function of SL-PRS quality of service (QoS), and one or more SL reference signal received power (RSRP) thresholds as a function of SL-PRS QoS; transmitting a first SL-PRS having an associated QoS at a first power derived from the first set of OLPC parameters; receiving a measurement report from a peer WTRU, the measurement report comprising a SL RSRP for the first SL-PRS; and On condition that the received SL RSRP is lower than a SL RSRP threshold corresponding to the associated SL-PRS QoS, a second SL-PRS is transmitted at a second power having the delta power offset corresponding to the associated QoS. 2 . The method according to claim 1 , wherein the second SL-PRS is transmitted using the OLPC parameter of the first SL-PRS under the condition that the received SL RSRP is equal to or greater than the SL RSRP threshold. 3 . 3 . The method of claim 1 , wherein the OLPC parameters include P0 and α for SL and / or DL ​​path loss.

4. The method of claim 1 , wherein the WTRU determines whether to use a sidelink transmission of the SL-PRS or data to measure the SL-RSRP for OLPC based on a pre-configured type of a resource pool for transmitting the SL-PRS.

5. The method of claim 1, wherein the function of SL-PRS QoS comprises low QoS, medium QoS, or high QoS. The method according to claim 3 , wherein the OLPC parameters P0 and α are configured per resource pool.

7. The method of claim 1, wherein the WTRU determines which SL path loss to use to derive the OLPC Tx power for sending the SL-PRS based on the availability of each SL path loss and the configured priority or precedence of each path loss.

8. A wireless transmit receive unit (WTRU), the wireless transmit receive unit (WTRU) comprising: a transmitter and a receiver in communication with the processor, the receiver configured to receive configuration information including open loop power control (OLPC) parameters for sidelink (SL) positioning reference signal (PRS) transmissions, one or more delta power offsets as a function of SL-PRS quality of service (QoS), and one or more SL reference signal received power (RSRP) thresholds as a function of the SL-PRS QoS; The transmitter is configured to transmit a first SL-PRS having an associated QoS at a first power derived from the first set of OLPC parameters; The receiver is configured to receive a measurement report from a peer WTRU, the measurement report comprising a SL RSRP of the first SL-PRS; and The processor is configured to determine a condition that the received SL RSRP is below a SLRSRP threshold corresponding to the associated SL-PRS QoS, and to initiate the transmitter to transmit a second SL-PRS at a second power having the delta power offset corresponding to the associated QoS.

9. The WTRU of claim 8, wherein the processor is configured to determine a condition that the received SL RSRP is equal to or greater than the SL RSRP threshold, and to initiate the transmitter to transmit the second SL-PRS using the OLPC parameters of the first SL-PRS.

10. The WTRU of claim 8, wherein the OLPC parameters include P0 and α for SL and / or DL ​​path loss.

11. The WTRU of claim 8, wherein the processor is further configured to determine whether to use a sidelink transmission of the SL-PRS or data to measure the SL-RSRP for OLPC based on a pre-configured type of a resource pool for transmitting the SL-PRS.

12. The WTRU of claim 8, wherein the function of SL-PRS QoS comprises low QoS, medium QoS, or high QoS.

13. The WTRU of claim 8, wherein the OLPC parameters P0 and α are configured per resource pool.

14. The WTRU of claim 8, wherein the processor is further configured to determine which SL path loss to use to derive the OLPC Tx power for transmitting the SL-PRS based on the availability of each SL path loss and a configured priority or precedence of each path loss.

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