NR relay-method for multipath discovery, relay selection and network reporting

Abstract

A wireless transmit / receive unit (WTRU) may receive configuration information that may indicate one or more parameters for operation as a WTRU to a network mobile relay. The parameter may include a first reference signal power (RSRP) threshold and / or a second RSRP threshold. The WTRU may perform an RSRP measurement of a serving cell to determine an RSRP value. The WTRU may determine whether to indicate support of one or more of a single-path operation and a multi-path operation in a sidelink discovery message based on the RSRP value. The WTRU may indicate support for multipath relay operation based on the RSRP value satisfying the second RSRP threshold. The WTRU may indicate support for a single path relay operation based on the RSRP value satisfying the first RSRP threshold. The WTRU may transmit a sidelink discovery message indicating support for a single-path relay operation and / or a multi-path relay operation based on the RSRP value.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 327,578 filed on April 5, 2022, U.S. Provisional Patent Application No. 63 / 410,817 filed on September 28, 2022, and U.S. Provisional Patent Application No. 63 / 445,332 filed on February 14, 2023, the entire contents of which are incorporated herein by reference. Background Art

[0003] New Radio (NR) sidelink relaying may be performed. For example, wireless transmit / receive unit (WTRU) to network (W2N) relaying and / or WTRU to WTRU (W2W) relaying may be used based on PC5 (eg, sidelink).

[0004] NR sidelink can focus on supporting road safety services related to vehicle-to-everything (V2X). For example, support for broadcast, multicast and / or unicast communications can be provided in both out-of-coverage scenarios and in-network coverage scenarios. Considering a wider range of applications and services, sidelink-based relay functionality can be studied to extend the sidelink / network coverage and improve power efficiency.

[0005] W2N coverage may be extended. Uu coverage reachability may be useful for a WTRU to reach a server in a PDN network or a corresponding WTRU outside a neighboring area. However, current solutions for W2N relaying may be limited to EUTRA-based technologies for both NG-RAN and NR-based sidelink communications, and therefore may not be applicable to NR-based systems.

[0006] W2W coverage can be extended. Proximity reachability may be limited to a single-hop side link via EUTRA-based or NR-based side link technology. However, this may not be enough in scenarios without Uu coverage, given the limited single-hop side link coverage. Side link connectivity can be further extended in the NR framework to support enhanced quality of service (QoS) requirements. Summary of the invention

[0007] A discovery transmission may be performed. The WTRU may support and / or request one or more relay services. The WTRU may perform discovery-relay-service message transmission. The WTRU may receive a (pre) configuration for discovery-relay-service transmission. The WTRU may indicate to the network the relay service capabilities it supports. The WTRU may receive an indication from the network indicating a relay type (e.g., which type of relay it should be). The WTRU may request resources for discovery-relay-service transmission. The WTRU may perform transmission of a discovery-relay-service message. The WTRU may determine which discovery-relay-service message to send. The WTRU may determine a quality of service (QoS) associated with the discovery-relay-service message. The WTRU may determine a resource pool for sending a discovery-relay-service message. The WTRU may determine transmission parameters for a discovery-relay-service message. The WTRU may determine information to include in a discovery message.

[0008] Relay selection may be performed. The WTRU may trigger relay selection. The WTRU may determine which relay to (re)select. The WTRU may determine whether to perform relay reselection and / or report a detected set of relays to the network.

[0009] The WTRU may report a set of detected remote WTRUs and / or a set of detected relays. The WTRU may request resources for discovery-relay-service transmission. The WTRU may receive an indication for sending a discovery-relay-service message. The WTRU may trigger a cell reselection. The WTRU may determine which cell to prioritize / report.

[0010] In an example, a WTRU (e.g., a relay WTRU) may determine one or more of: which discovery-relay-service message to send, one or more discovery transmission parameters, and a resource pool to use for sending the discovery message based on Uu reference signal received power (RSRP), relay load, and / or WTRU relay capabilities.

[0011] For example, the WTRU may be (pre)configured (e.g., via a dedicated RRC or SIB) with conditions for sending multipath and / or single path discovery messages. Alternatively or additionally, the WTRU may receive (e.g., via a dedicated RRC or SIB) conditions for sending multipath and / or single path discovery messages. The discovery message may include one or more of: a Uu RSRP range (e.g., a minimum Uu RSRP and a maximum Uu RSRP) for single path discovery, a (e.g., different) minimum Uu RSRP for multipath discovery, relay capabilities (e.g., which may include support for single path and / or multipath relaying), and / or one or more (e.g., each) types of discovery messages. Quality of Service (QoS) (e.g., priority) and a sending resource pool. The WTRU may determine which type of discovery message to send based on one or more of the WTRU's measured Uu RSRP, relay load, and the WTRU's ability to support multipath and / or single path relaying. In an example, for high load situations (e.g., network expansion may be prioritized), the WTRU may be allowed to (e.g., only) send single path discoveries. The WTRU may select a resource pool for sending the discovery message based on the discovery type. The WTRU may use the (pre-)configured QoS of the discovery message to determine the sending parameters of the discovery message. The WTRU may indicate one or more of the following in the discovery message: the discovery type (e.g., single path and / or multipath), the Uu RSRP (e.g., for the remote WTRU to perform relay selection), and / or the QoS of the discovery message. The WTRU may perform discovery sending.

[0012] In an example, a WTRU (e.g., a remote WTRU) may determine whether to send single-path and / or multi-path discovery based on one or more of the WTRU's measured Uu RSRP, received SLRB / LCH configuration for multi-path, and / or arrival data from the SLRB / LCH set in the buffer. When sending multi-path discovery, the WTRU may select / report (e.g., to the gNB) a set of relays that support multi-path and have an appropriate Uu RSRP.

[0013] For example, a WTRU (e.g., a remote WTRU) may be (pre)configured with or may receive (e.g., via a dedicated RRC or SIB) conditions for sending a discovery message. The discovery message may include one or more of: a maximum Uu RSRP for single path discovery, a Uu RSRP range for multipath discovery (e.g., a minimum Uu RSRP and (e.g., different) maximum Uu RSRP), a set of SLRB / LCHs for triggering multipath discovery, and / or a minimum Uu RSRP for relays per SLRB / LCH. The WTRU may perform one or more of the following: trigger discovery transmission upon receiving SLRB / LCH configuration and / or arrival of SLRB / LCH data that meets the configuration conditions for multipath relaying; perform relay response reception; and / or perform relay selection or select a relay set to notify the network, the relay set meeting the following conditions: supporting multipath; supporting the established SLRB / LCH; and the Uu RSRP of the relay is above a threshold, which may be based on the SLRB / LCH of the remote WTRU. For example, if the Uu threshold for single-path transmission is not met, but the threshold for multi-path discovery is met, the WTRU may perform one or more of the following: trigger discovery transmission upon receiving SLRB / LCH configuration and / or arrival of SLRB / LCH data that meets the configuration conditions for multi-path relay; perform relay response reception; and / or perform relay selection or select a relay set to notify the network, which relay set meets the following conditions: supports multi-path; supports the established SLRB / LCH; and the Uu RSRP of the relay is higher than a threshold, which threshold may be based on the SLRB / LCH of the remote WTRU.

[0014] The relay WTRU may determine which set of detected remote WTRUs to report to the network. Additionally or alternatively, the WTRU (e.g., relay WTRU) may determine which set of detected relays to report to the network. The relay WTRU may indicate (e.g., send) information in a discovery message. The remote WTRU may indicate (e.g., send) its Uu connection status in a discovery-service message. The WTRU may determine to send the discovery-relay-service message. The WTRU may determine whether a cell supports one or more relay services. The WTRU may determine whether to send a discovery-relay-service message based on an indication from the cell. The WTRU may determine whether to respond to the remote WTRU (e.g., send to the remote WTRU). The WTRU may determine its load.

[0015] A WTRU (e.g., a first WTRU) may monitor one or more discovery messages. The one or more discovery messages may come from one or more second WTRUs. The WTRU may determine a set of the one or more second WTRUs, for example, based on the discovery message. The WTRU may report the set of the one or more second WTRUs, for example, to a network. The set of the one or more second WTRUs may be based on a support type. The support type may include one or more services in a single path service and a multipath service. The WTRU may compare a second WTRU reference signal received power (RSRP) with a threshold. The WTRU may determine the support type based on a comparison of the second WTRU RSRP with the threshold. For example, if the second WTRU RSRP is less than the threshold, the WTRU may determine that the support type is a single path service. In another example, if the second WTRU RSRP is less than the threshold, the WTRU may determine that the support type is a single path service. The WTRU may determine the support type based on the connection state of the second WTRU. The WTRU may compare the second WTRU quality of service (QoS) with a threshold.

[0016] A WTRU (e.g., a relay WTRU) may receive configuration information. The configuration information may indicate one or more parameters. The one or more parameters may be used to operate as a WTRU to network mobile relay. Additionally or alternatively, the parameters may include a first reference signal power (RSRP) threshold and / or a second RSRP threshold.

[0017] The WTRU may perform RSRP measurements, for example, to determine an RSRP value. For example, the WTRU may receive a signal from the network (e.g., a serving cell of the network) and may perform the RSRP measurement on the received signal. The WTRU may determine whether to indicate support for one or more operations of single-path operation and multi-path operation. The WTRU may determine, for example, based on the RSRP value, whether to indicate support for one or more operations of single-path operation and multi-path operation in a sidelink discovery message. The WTRU may indicate support for multipath relay operation based on the RSRP value satisfying the second RSRP threshold. Additionally or alternatively, the WTRU may indicate support for single-path relay operation based on the RSRP value satisfying the first RSRP threshold. The WTRU may send, for example, the sidelink discovery message indicating support for one or more operations of single-path relay operation and multi-path relay operation. For example, the WTRU may send the sidelink discovery message indicating support for one or more operations of single-path relay operation and multi-path relay operation based on the RSRP value.

[0018] The parameter may include a relay load range. The WTRU may indicate support for the multipath relay operation based on the current relay load of the WTRU (e.g., less than the relay load range). The parameter may include an indication of a first resource pool and / or an indication of a second resource pool. The first resource pool may be used to send, for example, a first side link discovery message indicating support for the single path relay operation. The second resource pool may be used to send, for example, a second side link discovery message indicating support for the multipath relay operation. The side link discovery message may indicate the RSRP value. When the RSRP value is greater than or equal to the first RSRP threshold, the WTRU may indicate support for the single path relay operation. Additionally or alternatively, when the RSRP value is less than the second RSRP threshold, the WTRU may indicate support for the single path relay operation.

[0019] When the RSRP value is greater than or equal to the second RSRP threshold, the WTRU may indicate support for the multipath relay operation. The WTRU may, for example, send a report to the network based on the RSRP value. The report may indicate one or more second WTRUs. For example, when the RSRP value meets the first RSRP threshold, the report may indicate one or more second WTRUs requesting the single path relay operation. Additionally or alternatively, when the RSRP value meets the second RSRP threshold, the report may indicate one or more second WTRUs requesting the multipath relay operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1A is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented;

[0021] 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 the illustrated communication system;

[0022] 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;

[0023] 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;

[0024] Figure 2 An example user plane radio protocol stack for an L2 evolved WTRU to a network relay (e.g., PC5) is illustrated;

[0025] Figure 3 An example control plane radio protocol stack for an L2 evolved WTRU to a network relay (e.g., PC5) is illustrated;

[0026] Figure 4 An example is illustrated of a WTRU determining whether to send a single path discovery versus a multi-path discovery and a single path request versus a multi-path request; and

[0027] Figure 5 illustrates an example where a remote WTRU gives priority to a relay WTRU associated with a gNB (with a measured Uu RSRP greater than or equal to a threshold); and

[0028] Figure 6 An example is illustrated in which a relay WTRU determines whether to send single-path discovery versus multi-path discovery based on the measured Uu RSRP being greater than or equal to a threshold. DETAILED DESCRIPTION

[0029] 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 DFT spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multi-carrier (FBMC), etc.

[0030] like Figure 1AAs shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RAN 104 / 113, CN 106 / 115, public switched telephone network (PSTN) 108, Internet 110 and other networks 112, but it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d (any of which may be referred to as a “station” and / or “STA”) may be configured to send and / or receive wireless signals and may include 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), a consumer electronic device, a device operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0031] The communication system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device that is configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106 / 115, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node B, an eNode B, a Home Node B, a Home eNode B, a gNB, an NR Node B, a site controller, an access point (AP), a wireless router, and the like. While 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.

[0032] The base station 114a may be part of the RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), a relay node, etc. The base station 114a and / or the 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 licensed and unlicensed spectrums. 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, a cell associated with the base station 114a may be divided into three sectors. Therefore, in one embodiment, the base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In an embodiment, the 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.

[0033] 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).

[0034] 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, SC-FDMA, etc. For example, the base station 114a in the RAN 104 / 113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may use Wideband CDMA (WCDMA) to establish the air interface 115 / 116 / 117. WCDMA may include communication protocols such as High Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High Speed ​​UL Packet Access (HSUPA).

[0035] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA) that may establish the air interface 116 using Long Term Evolution (LTE) and / or Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-A Pro).

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

[0037] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may 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).

[0038] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), etc.

[0039] Figure 1AThe base station 114b in the may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in a local area, such as a business location, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology (such as IEEE 802.11) to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology (such as IEEE 802.15) to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a picocell or a femtocell. As Figure 1A As shown, base station 114b may have a direct connection to Internet 110. Therefore, base station 114b may not need to access Internet 110 via CN 106 / 115.

[0040] The RAN 104 / 113 may be in communication with the CN 106 / 115, which may be any type of network configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform advanced security functions, such as user authentication. Although not described in detail in the text, the CN 106 / 115 may be configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform advanced security functions, such as user authentication. Figure 1A Although not shown in the figure, it will be appreciated that the RAN 104 / 113 and / or the CN 106 / 115 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 / 113 or a different RAT. For example, in addition to being connected to the RAN 104 / 113, which may utilize NR radio technology, the CN 106 / 115 may also be in communication with another RAN (not shown) that employs GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0041] The CN 106 / 115 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network 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 / 113 or a different RAT.

[0042] 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.

[0043] 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.

[0044] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a 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.

[0045] 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 the 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, IR, UV or visible light signals. In another embodiment, the send / receive element 122 may be configured to send and / or receive both RF signals and optical signals. It should be understood that the send / receive element 122 may be configured to send and / or receive any combination of wireless signals.

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

[0047] 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.

[0048] 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, a secure digital (SD) memory card, and the like. 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).

[0049] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control power to other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. 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.

[0050] 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.

[0051] 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, module, a frequency modulation (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, etc. Peripheral device 138 may include one or more sensors, which 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 geolocation sensor; an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0052] The WTRU 102 may include a full-duplex radio for which transmission and reception of some or all signals (e.g., associated with specific subframes for UL (e.g., for transmission) and downlink (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit 139 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 WRTU 102 may include a half-duplex radio for which transmission and reception of some or all signals (e.g., associated with specific subframes for UL (e.g., for transmission) or downlink (e.g., for reception)) may be concurrent and / or simultaneous.

[0053] 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.

[0054] 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.

[0055] 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, scheduling of users in UL and / or DL, etc. Figure 1C As shown, the eNode-Bs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0056] Figure 1C The illustrated CN 106 may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements is depicted as being part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0057] 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, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, etc. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0058] 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 inter-evolved Node-B handover, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, and the like.

[0059] 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.

[0060] 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.

[0061] 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 communication interface with a communication network.

[0062] In a representative embodiment, the other network 112 may be a WLAN.

[0063] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for the BSS and one or more stations (STA) 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 leading to the STA may be reached by the AP and may be delivered to the STA. Traffic originating from the STA and leading 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 by 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 establishment (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.

[0064] When using the 802.11ac infrastructure operating mode or a similar operating mode, the AP may send beacons on a fixed channel (such as a primary channel). The primary channel may be a fixed width (e.g., a 20 MHz wide bandwidth) or a width dynamically set via signaling. The primary channel may be an operating channel of the BSS and may be used by the STA to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access / collision avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. For CSMA / CA, a STA (e.g., each STA) (including the AP) may listen to the primary channel. If the primary channel is listened / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0065] High throughput (HT) STAs may communicate using a 40 MHz wide channel, for example, via a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0066] 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 data can be sent by sending STA. At the receiver of the receiving STA, the above-mentioned operation for 80+80 configuration can be reversed, and the combined data can be transmitted to the medium access control (MAC).

[0067] 802.11af and 802.11ah support operating modes below 1GHz. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah relative to those used in 802.11n and 802.11ac. 802.11af supports 5MHz, 10MHz, and 20MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support instrument type control / machine type communications, such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support for (e.g., only support for) certain bandwidths and / or limited bandwidths. MTC devices may include batteries with battery life above a threshold (e.g., to maintain very long battery life).

[0068] WLAN systems that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) include channels that can be designated as primary channels. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA (which supports the minimum bandwidth operating mode) from all STAs operating in the BSS. In the example of 802.11ah, for STAs (e.g., MTC-type devices) that support (e.g., only support) a 1MHz mode, the primary channel may be 1MHz wide, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) settings may depend on the state of the primary channel. If the primary channel is busy, for example, because a STA (supporting only a 1MHz operating mode) is sending to the AP, the entire available frequency band may be considered busy even if most of the frequency bands remain idle and may be available.

[0069] 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.

[0070] Figure 1D 1 is a system diagram illustrating the RAN 113 and the CN 115 in accordance with an embodiment. As noted above, the RAN 113 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0071] The RAN 113 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. 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, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on an unlicensed spectrum, while the remaining component carriers may be on a licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) technology. For example, the WTRU 102a may receive coordinated transmissions from the gNB 180a and the gNB 180b (and / or the gNB 180c).

[0072] 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 transmit time intervals (TTIs) of varying or scalable lengths (e.g., containing different numbers of OFDM symbols and / or varying absolute time lengths over time).

[0073] 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 anchors. 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 gNBs 180a, 180b, 180c while also communicating / connecting with another RAN, such as the eNode-Bs 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 eNode-Bs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNode-Bs 160a, 160b, 160c may act as mobility anchors for the WTRUs 102a, 102b, 102c, and the gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0074] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and / or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards a user plane function (UPF) 184a, 184b, 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.

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

[0076] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N2 interface and may act as a control node. 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 PDU sessions with different requirements), selecting a specific SMF 183a, 183b, management of registration areas, termination of NAS signaling, mobility management, etc. The AMF 182a, 182b may use network slicing to customize CN support for the WTRU 102a, 102b, 102c based on the type of services utilized by the WTRU 102a, 102b, 102c. 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 mobile broadband (eMBB) access, services for machine type communication (MTC) access, etc. The AMF 162 may provide a control plane function for switching between the RAN 113 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies, such as WiFi.

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

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

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

[0080] Given that Figures 1A to 1D as well as Figures 1A to 1D , one or more or all of the functions described herein for one or more of the following may be performed by one or more simulation devices (not shown): WTRU 102a-102d, base station 114a-114b, evolved Node B 160a-160c, MME 162, SGW 164, PGW 166, gNB 180a-180c, AMF 182a-182ab, UPF 184a-184b, SMF 183a-183b, DN 185a-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 may be used to test other devices and / or simulate network and / or WTRU functions.

[0081] 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. The simulation device may be directly coupled to another device for testing purposes and / or may use over-the-air wireless communications to perform testing.

[0082] One or more simulation devices can perform one or more (including all) functions without being implemented / deployed as part of a wired and / or wireless communication network. For example, the simulation device can be used in a test scenario in a test laboratory and / or 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 may include one or more antennas) can be used by the simulation device to send and / or receive data.

[0083] A discovery transmission may be performed. The WTRU may support and / or request one or more relay services. The WTRU may perform discovery-relay-service message transmission. The WTRU may receive a (pre) configuration for discovery-relay-service transmission. The WTRU may indicate to the network the relay service capabilities it supports. The WTRU may receive an indication from the network indicating a relay type (e.g., which type of relay it should be). The WTRU may request resources for discovery-relay-service transmission. The WTRU may perform transmission of a discovery-relay-service message. The WTRU may determine which discovery-relay-service message to send. The WTRU may determine a quality of service (QoS) associated with the discovery-relay-service message. The WTRU may determine a resource pool for sending a discovery-relay-service message. The WTRU may determine transmission parameters for a discovery-relay-service message. The WTRU may determine information to include in a discovery message.

[0084] Relay selection may be performed. The WTRU may trigger relay selection. The WTRU may determine which relay to (re)select. The WTRU may determine whether to perform relay reselection and / or report a detected set of relays to the network.

[0085] The WTRU may report a set of detected remote WTRUs and / or a set of detected relays. The WTRU may request resources for discovery-relay-service transmission. The WTRU may receive an indication for sending a discovery-relay-service message. The WTRU may trigger a cell reselection. The WTRU may determine which cell to prioritize / report.

[0086] In an example, a WTRU (e.g., a relay WTRU) may determine one or more of: which discovery-relay-service message to send, one or more discovery transmission parameters, and a resource pool to use for sending the discovery message based on Uu reference signal received power (RSRP), relay load, and / or WTRU relay capabilities.

[0087] For example, the WTRU may be (pre)configured (e.g., via a dedicated RRC or SIB) with conditions for sending multipath and / or single path discovery messages. Alternatively or additionally, the WTRU may receive (e.g., via a dedicated RRC or SIB) conditions for sending multipath and / or single path discovery messages. The discovery message may include one or more of: a Uu RSRP range (e.g., a minimum Uu RSRP and a maximum Uu RSRP) for single path discovery, a (e.g., different) minimum Uu RSRP for multipath discovery, relay capabilities (e.g., which may include support for single path and / or multipath relaying), and / or one or more (e.g., each) types of discovery messages. Quality of Service (QoS) (e.g., priority) and a sending resource pool. The WTRU may determine which type of discovery message to send based on one or more of the WTRU's measured Uu RSRP, relay load, and the WTRU's ability to support multipath and / or single path relaying. In an example, for high load situations (e.g., network expansion may be prioritized), the WTRU may be allowed to (e.g., only) send single path discoveries. The WTRU may select a resource pool for sending the discovery message based on the discovery type. The WTRU may use the (pre-)configured QoS of the discovery message to determine the sending parameters of the discovery message. The WTRU may indicate one or more of the following in the discovery message: the discovery type (e.g., single path and / or multipath), the Uu RSRP (e.g., for the remote WTRU to perform relay selection), and / or the QoS of the discovery message. The WTRU may perform discovery sending.

[0088] In an example, a WTRU (e.g., a remote WTRU) may determine whether to send single-path and / or multi-path discovery based on one or more of the WTRU's measured Uu RSRP, received SLRB / LCH configuration for multi-path, and / or arrival data from the SLRB / LCH set in the buffer. When sending multi-path discovery, the WTRU may select / report (e.g., to the gNB) a set of relays that support multi-path and have an appropriate Uu RSRP.

[0089] For example, a WTRU (e.g., a remote WTRU) may be (pre)configured with or may receive (e.g., via a dedicated RRC or SIB) conditions for sending a discovery message. The discovery message may include one or more of: a maximum Uu RSRP for single path discovery, a Uu RSRP range for multipath discovery (e.g., a minimum Uu RSRP and (e.g., different) maximum Uu RSRP), a set of SLRB / LCHs for triggering multipath discovery, and / or a minimum Uu RSRP for relays per SLRB / LCH. The WTRU may perform one or more of the following: trigger discovery transmission upon receiving SLRB / LCH configuration and / or arrival of SLRB / LCH data that meets the configuration conditions for multipath relaying; perform relay response reception; and / or perform relay selection or select a relay set to notify the network, the relay set meeting the following conditions: supporting multipath; supporting the established SLRB / LCH; and the Uu RSRP of the relay is above a threshold, which may be based on the SLRB / LCH of the remote WTRU. For example, if the Uu threshold for single-path transmission is not met, but the threshold for multi-path discovery is met, the WTRU may perform one or more of the following: trigger discovery transmission upon receiving SLRB / LCH configuration and / or arrival of SLRB / LCH data that meets the configuration conditions for multi-path relay; perform relay response reception; and / or perform relay selection or select a relay set to notify the network, which relay set meets the following conditions: supports multi-path; supports the established SLRB / LCH; and the Uu RSRP of the relay is higher than a threshold, which threshold may be based on the SLRB / LCH of the remote WTRU.

[0090] The relay WTRU may determine which set of detected remote WTRUs to report to the network. Additionally or alternatively, the WTRU (e.g., relay WTRU) may determine which set of detected relays to report to the network. The relay WTRU may indicate (e.g., send) information in a discovery message. The remote WTRU may indicate (e.g., send) its Uu connection status in a discovery-service message. The WTRU may determine to send the discovery-relay-service message. The WTRU may determine whether a cell supports one or more relay services. The WTRU may determine whether to send a discovery-relay-service message based on an indication from the cell. The WTRU may determine whether to respond to the remote WTRU (e.g., send to the remote WTRU). The WTRU may determine its load.

[0091] A WTRU (e.g., a first WTRU) may monitor one or more discovery messages. The one or more discovery messages may come from one or more second WTRUs. The WTRU may determine a set of the one or more second WTRUs, for example, based on the discovery message. The WTRU may report the set of the one or more second WTRUs, for example, to a network. The set of the one or more second WTRUs may be based on a support type. The support type may include one or more services in a single path service and a multipath service. The WTRU may compare a second WTRU reference signal received power (RSRP) with a threshold. The WTRU may determine the support type based on a comparison of the second WTRU RSRP with the threshold. For example, if the second WTRU RSRP is less than the threshold, the WTRU may determine that the support type is a single path service. In another example, if the second WTRU RSRP is less than the threshold, the WTRU may determine that the support type is a single path service. The WTRU may determine the support type based on the connection state of the second WTRU. The WTRU may compare the second WTRU quality of service (QoS) with a threshold.

[0092] A WTRU (e.g., a relay WTRU) may receive configuration information. The configuration information may indicate one or more parameters. The one or more parameters may be used to operate as a WTRU to network mobile relay. Additionally or alternatively, the parameters may include a first reference signal power (RSRP) threshold and / or a second RSRP threshold.

[0093] The WTRU may perform RSRP measurements. The WTRU may perform RSRP measurements of a serving cell, for example to determine an RSRP value. The WTRU may determine whether to indicate support for one or more of single-path operation and multi-path operation. The WTRU may determine, for example, based on the RSRP value, whether to indicate support for one or more of single-path operation and multi-path operation in a side link discovery message. The WTRU may indicate support for multi-path relay operation based on the RSRP value satisfying the second RSRP threshold. Additionally or alternatively, the WTRU may indicate support for single-path relay operation based on the RSRP value satisfying the first RSRP threshold. The WTRU may send, for example, the side link discovery message indicating support for one or more of single-path relay operation and multi-path relay operation. For example, the WTRU may send, based on the RSRP value, the side link discovery message indicating support for one or more of single-path relay operation and multi-path relay operation.

[0094] The parameter may include a relay load range. The WTRU may indicate support for the multipath relay operation based on the current relay load of the WTRU (e.g., less than the relay load range). The parameter may include an indication of a first resource pool and / or an indication of a second resource pool. The first resource pool may be used to send, for example, a first side link discovery message indicating support for the single path relay operation. The second resource pool may be used to send, for example, a second side link discovery message indicating support for the multipath relay operation. The side link discovery message may indicate the RSRP value. When the RSRP value is greater than or equal to the first RSRP threshold, the WTRU may indicate support for the single path relay operation. Additionally or alternatively, when the RSRP value is less than the second RSRP threshold, the WTRU may indicate support for the single path relay operation.

[0095] When the RSRP value is greater than or equal to the second RSRP threshold, the WTRU may indicate support for the multipath relay operation. The WTRU may, for example, send a report to the network based on the RSRP value. The report may indicate one or more second WTRUs. For example, when the RSRP value meets the first RSRP threshold, the report may indicate one or more second WTRUs requesting the single path relay operation. Additionally or alternatively, when the RSRP value meets the second RSRP threshold, the report may indicate one or more second WTRUs requesting the multipath relay operation.

[0096] Figure 2 An example system 200 is illustrated that illustrates a user plane radio protocol stack for an L2 evolved WTRU to a network relay (e.g., PC5). Figure 2A remote WTRU 202, an L2 relay WTRU 204, an eNB 206, and a core network (CN) 208 are illustrated. The PC5 interface between the remote WTRU 202 and the L2 relay WTRU 204 may be associated with (e.g., lower) layers, such as including one or more of a physical layer (PHY), a MAC layer, and a radio link control (RLC) layer. The Uu interface between the L2 relay WTRU 204 and the eNB 206 may be associated with (e.g., lower) layers, such as including one or more of an adaptation layer, a physical layer (PHY), a MAC layer, and a radio link control (RLC) layer. The interfaces (e.g., S1-U / S5 / S8) between the eNB 206 and the CN 208 may be associated with L1 / L2.

[0097] Figure 3 An example system 300 is illustrated that illustrates a control plane radio protocol stack for an L2 evolved WTRU to a network relay (e.g., PC5). Figure 3 A remote WTRU 302, an L2 relay WTRU 304, an eNB 306, and a core network (CN) 308 are illustrated. The PC5 interface between the remote WTRU 302 and the L2 relay WTRU 304 may be associated with (e.g., lower) layers, such as including one or more of a physical layer (PHY), a MAC layer, and a radio link control (RLC) layer. The Uu interface between the L2 relay WTRU 304 and the eNB 306 may be associated with (e.g., lower) layers, such as including one or more of an adaptation layer, a physical layer (PHY), a MAC layer, and a radio link control (RLC) layer. The interface between the eNB 306 and the CN 308 (e.g., S1-MME) may be associated with L1 / L2.

[0098] The ProSe WTRU to network relay may perform relaying (e.g., be used as a relay). For example, the ProSe WTRU to network relay may be used as a relay to extend network coverage to an out-of-coverage WTRU by using PC5 (D2D) between the out-of-coverage WTRU and the WTRU to network relay.

[0099] The ProSe WTRU to Network Relay may provide forwarding functionality. For example, the ProSe WTRU to Network Relay may provide a generic L3 forwarding functionality. The forwarding functionality may relay any type of IP service between the remote WTRU and the network. One-to-one and / or one-to-many sidelink communications may be transmitted between the remote WTRU and the ProSe WTRU to Network Relay. For the remote WTRU and the relay WTRU, (e.g., only) one carrier (e.g., public safety ProSe carrier) operation may be supported (e.g., for the relay / remote WTRU, Uu and PC5 should be the same carrier). The remote WTRU may be authorized. For example, the remote WTRU may be authorized by one or more upper layers. Alternatively or additionally, the remote WTRU may be in the coverage of the public safety ProSe carrier or outside the coverage of any supported carrier (including the public safety ProSe carrier for WTRU to Network Relay discovery, (re)selection and / or communication). The ProSe WTRU to Network Relay may be (e.g., always) within the coverage of the EUTRAN. The ProSe WTRU to network relay and remote WTRU may perform sidelink communication and / or sidelink discovery as described in one or more specifications.

[0100] Relay selection of a WTRU to a network relay may be performed. For example, relay selection / reselection of a ProSe WTRU to a network relay may be performed. Relay selection may be based on one or more of an AS layer quality measurement (RSRP) and / or upper layer criteria. For example, the eNB may control whether a WTRU may be a ProSe WTRU to a network relay. ProSe WTRU to a network relay operation may be supported in a cell. For example, if the eNB broadcasts (e.g., any) information associated with the ProSe WTRU to a network relay operation, the ProSe WTRU to a network relay operation may be supported in the cell. The eNB may provide transmission resources. Transmission resources may be used for ProSe WTRU to network relay discovery. Additionally or alternatively, the transmission resources may use broadcast signaling for an RRC_IDLE state and / or dedicated signaling for an RRC_CONNECTED state and / or receive resources for ProSe WTRU to network relay discovery using broadcast signaling.

[0101] The eNB may broadcast minimum and / or maximum Uu link quality (RSRP) thresholds. The minimum and / or maximum Uu link quality (RSRP) thresholds may be thresholds that a ProSe WTRU to network relay may meet before initiating a WTRU to network relay discovery procedure. The WTRU may use the thresholds to autonomously start and / or stop the WTRU to network relay discovery procedure. For example, when in RRC_IDLE, when the eNB broadcasts the send resource pool, the WTRU may use the thresholds to autonomously start and / or stop the WTRU to network relay discovery procedure. The WTRU may use the thresholds to determine whether the WTRU may indicate a relay WTRU state (e.g., that it is a relay WTRU) to the eNB and / or may (e.g., desire to) start ProSe WTRU to network relay discovery. For example, when in RRC_CONNECTED, the WTRU may use the thresholds to determine whether it may indicate a relay WTRU state (e.g., that it is a relay WTRU) to the eNB and / or may (e.g., desire to) start ProSe WTRU to network relay discovery. For example, subject to the (e.g., these broadcasted) thresholds, the WTRU may initiate a request for ProSe WTRU to network relay discovery resources through dedicated signaling. For example, if the eNB does not broadcast a transmit resource pool for ProSe WTRU to network relay discovery, then subject to the (e.g., these broadcasted thresholds), the WTRU may initiate a request for ProSe WTRU to network relay discovery resources through dedicated signaling.

[0102] The ProSe WTRU to network relay may perform sidelink communications (e.g., for ProSe WTRU to network relay operations). For example, while in RRC_CONNECTED, the ProSe WTRU to network relay may perform sidelink communications for ProSe WTRU to network relay operations. The ProSe WTRU to network relay may indicate to the eNB that it is a ProSe WTRU to network relay and / or that it may (e.g., be intended to) perform ProSe WTRU to network relay sidelink communications. For example, after receiving a Layer 2 Link Establishment Request and / or a TMGI Monitoring Request (e.g., an upper layer message) from a remote WTRU, the ProSe WTRU to network relay may indicate to the eNB that it is a ProSe WTRU to network relay and / or that it may (e.g., be intended to) perform ProSe WTRU to network relay sidelink communications. The eNB may provide resources for ProSe WTRU to network relay communications.

[0103] The remote WTRU may decide when to start monitoring for ProSe WTRU to network relay discovery. The remote WTRU may send a ProSe WTRU to network relay discovery request message. For example, the remote WTRU may send a ProSe WTRU to network relay discovery request message when it is in RRC_IDLE and / or in RRC_CONNECTED (e.g., according to the configuration of resources for ProSe WTRU to network relay discovery). The eNB may broadcast a threshold value. The threshold value may be used by the remote WTRU. For example, the threshold value may be used by the remote WTRU to determine whether the WTRU may send a ProSe WTRU to network relay discovery request message and / or connect or communicate with a ProSe WTRU to network relay WTRU. For example, the remote WTRU may use the broadcasted threshold value to determine whether the WTRU (e.g., the remote WTRU) may indicate to the eNB that it is a remote WTRU and / or may (e.g., desire to) participate in ProSe WTRU to network relay discovery and / or communication. Additionally or alternatively, the remote WTRU may be an RRC_CONNECTED remote WTRU. The eNB may provide transmit resources using broadcast and / or dedicated signaling and / or receive resources. For example, the eNB may provide transmit resources using broadcast signaling for ProSe WTRU to network relay operation. The remote WTRU may stop using ProSe WTRU to network relay discovery and / or communication resources. For example, the remote WTRU may stop using ProSe WTRU to network relay discovery and / or communication resources when the RSRP exceeds a broadcasted threshold.

[0104] The (eg, exact) time of traffic switching from Uu to PC5 and / or from PC5 to Uu may depend on the layer (eg, higher layer).

[0105] The remote WTRU may perform radio measurements at the PC5 interface. The remote WTRU may use the radio measurements (e.g., together with higher layer criteria) for ProSe WTRU to network relay selection and / or reselection. A ProSe WTRU to network relay may be selected (e.g., the ProSe WTRU to network relay is considered suitable in terms of radio standards). For example, if the PC5 link quality exceeds a configured threshold (e.g., pre-configured or provided by the eNB), the ProSe WTRU to network relay may be selected (e.g., the ProSe WTRU to network relay is considered suitable in terms of radio standards). The remote WTRU may select a ProSe WTRU to network relay that meets the higher layer criteria and / or has the best PC5 link quality among one or more (e.g., all) suitable ProSe WTRU to network relays.

[0106] The remote WTRU may trigger ProSe WTRU to network relay reselection. For example, the remote WTRU may trigger ProSe WTRU to network relay reselection when one or more of the following occurs: the current ProSe WTRU to network relay PC5 signal strength is lower than a configured signal strength threshold; and / or the remote WTRU receives a layer 2 (L2) link release message (e.g., an upper layer message) from the ProSe WTRU to network relay.

[0107] A WTRU to network relay for wearable devices may be used. For example, a WTRU to network relay for a business use case (e.g., customized for wearable devices and / or IoT devices) may be used. The WTRU to network relay for wearable devices may be an L2 relay (e.g., as opposed to a ProSe WTRU to network relay that may use an L3 (e.g., IP layer) relay approach). The WTRU to network relay for wearable devices may use one or more of the protocol stacks, such as Figure 2 and / or Figure 3 exemplified. Figure 2 An example user plane radio protocol stack for an L2 evolved WTRU to network relay (PC5) is illustrated. Figure 3 An example control plane radio protocol stack for an L2 evolved WTRU to network relay (PC5) is illustrated.

[0108] A single-hop W2N relay may be used. For the discovery model, one or more (e.g., two) models may be used for discovery and / or relay (re)selection. For example, in a first model, a W2N relay may transmit an announcement message. In a second model, a remote WTRU may transmit a request message to request relay service from another relay WTRU. The W2N relay may respond to the request message from the remote WTRU.

[0109] W2N relays may be used to extend network coverage. A WTRU may be configured with a Uu RSRP range of [min_Uu_RSRP, max_Uu_RSRP], for example, to send discovery messages (e.g., for discovery transmission). If max_Uu_RSRP ≥ Uu and / or RSRP ≥ min_Uu_RSRP, the WTRU may be allowed to send discovery messages.

[0110] Multipath relaying may be used. For example, for a multipath scenario, a WTRU (e.g., a remote WTRU) may be able to connect (e.g., simultaneously) to the same gNB using a direct path (e.g., via Uu) and / or an indirect path (e.g., via W2N relay). The multipath scenario may be targeted to improve system reliability and / or throughput.

[0111] For a multipath scenario, a WTRU (e.g., a relay WTRU) that does not meet max_Uu_RSRP (e.g., the WTRU is close to the cell center) may not be a good candidate for a remote WTRU in a single path, but may (e.g., still be) a good W2N relay for a remote WTRU in multipath. In addition, a relay may be able to support multipath (e.g., as a secondary branch but not a primary branch) and / or a single path (e.g., a Release 17 relay). Therefore, conditions for discovery and / or relay selection may be considered. For a remote WTRU, in some examples, the conditions for discovery transmission (e.g., Uu RSRP < threshold) may not be applicable to multipath. New conditions related to the need to set up multipath (e.g., reliability and throughput) and / or ensure QoS of network services may be useful (e.g., required). Therefore, discovery and relaying new discovery and / or relay selection procedures may be designed to support multipath scenarios.

[0112] As described herein, a WTRU may be (pre)configured with a parameter. The (pre)configuration of the parameter may be within a range (e.g., [a, b]) for performing a specific behavior. Omitting a boundary (a or b) from the (pre)configuration may be equivalent to (pre)configuring the boundary with the maximum or minimum achievable value of the parameter.

[0113] As used herein, a (pre)configured WTRU may be used interchangeably with a WTRU preconfigured with parameters and / or a WTRU configured with parameters (e.g., from a gNB via a dedicated RRC or SIB).

[0114] As used herein, the terms "relay selection" and "relay reselection" are used interchangeably.

[0115] One or more of the solutions described herein may be described for discovery-relay-service messages. Alternatively or additionally, the solutions described herein may be used and / or applicable to any discovery message or any other type of message (e.g., direct communication request (DCR) message).

[0116] The discovery transmission may be performed as described herein.For example, a WTRU may support one or more relay services.

[0117] A WTRU (e.g., a relay WTRU) may support one or more of the following relay services: single-path relay service; multi-path relay service, single-hop relay service; multi-hop relay service; layer 2 (L2) relay service; and / or layer 3 (L3) relay service.

[0118] The WTRU may support single path relay services. For example, for a single path relay service, a WTRU (e.g., a relay WTRU) may support relaying of Uu traffic of a remote WTRU in the uplink and / or downlink direction. The WTRU may also support monitoring of paging for a remote WTRU. The WTRU may support receiving a system information (SI) request from a remote WTRU and / or forwarding the request to a network. The WTRU may support forwarding SI information (e.g., an SI request) to a remote WTRU.

[0119] The WTRU may support multipath relay services. For example, for multipath relay services, a WTRU (e.g., a relay WTRU) may support relaying of Uu traffic of a remote WTRU in the uplink and / or downlink direction. The WTRU may not support monitoring of paging for a remote WTRU. In some examples, the WTRU may not support receiving SI requests from a remote WTRU. In some examples, the WTRU may not support forwarding SI for a remote WTRU.

[0120] The WTRU may support single-hop relay service. Alternatively or additionally, the WTRU may support relaying data directly from a source to a destination. For example, a relay WTRU supporting single-hop relay service may support relaying data directly from a source to a destination. In some examples, the WTRU may not support relaying data to and / or from an intermediate node. The source may be a gNB and / or another WTRU. Additionally or alternatively, the destination may be a gNB and / or another WTRU.

[0121] The WTRU may support multi-hop relay services. For example, a relay WTRU supporting multi-hop relay services may support relaying data from / to an intermediate node. Additionally or alternatively, the WTRU may support relaying data directly from a source to a destination. The source may be a gNB and / or another WTRU. Additionally or alternatively, the destination may be a gNB and / or another WTRU.

[0122] The WTRU may support L2 relay services. For example, a relay WTRU supporting L2 relay services may support receiving configuration for relaying data from the network. The relay WTRU may support one or more of monitoring paging, receiving SI requests, and / or forwarding SI information to a remote WTRU.

[0123] In an example, a relay WTRU may support (e.g., only) a single-path relay service, (e.g., only) a multi-path relay service, or both a single-path and a multi-path relay service. A WTRU may support (e.g., only) a single-hop relay service or a multi-hop relay service. Additionally or alternatively, a WTRU supporting a multi-hop relay service may support a single-hop relay service. For a remote WTRU, a WTRU may support (e.g., only) being a W2W relay, (e.g., only) being a W2N relay, or both being a W2W and W2N relay.

[0124] The WTRU may request one or more relay services. For example, a WTRU (e.g., a remote WTRU) may determine to request one or more of the following relay services: a single-path relay service; a multi-path relay service; a single-hop relay service; a multi-hop relay service; a layer 2 (L2) relay service; and / or a layer 3 (L3) relay service.

[0125] A WTRU may request a single path relay service. For example, a remote WTRU requesting a single path relay service may request a relay to forward Uu data from and / or to a gNB to and / or from the remote WTRU. A WTRU may request a relay service. A relay service request may include performing monitoring paging, receiving an SI request, and / or forwarding SI information to a remote WTRU.

[0126] The WTRU may request a multipath relay service. For example, a remote WTRU requesting a multipath relay service may request a relay WTRU to forward Uu data from / to the gNB to / from the remote WTRU. In some examples, the WTRU may not request one or more of the relay WTRUs to monitor paging, receive SI requests, and / or forward SI information for the remote WTRU.

[0127] A WTRU may request a single-hop relay service. For example, a remote WTRU may request (e.g., in a DISCOVERY-RELAY-SERVICE message) to connect to a WTRU-to-Network (W2N) relay. For example, a W2N relay may be directly connected to a gNB. A remote WTRU may request a single-hop relay service. For example, a remote WTRU may request (e.g., in a DISCOVERY-RELAY-SERVICE message) to connect to a WTRU-to-Network (U2N) relay. A WTRU-to-Network may be directly connected to a gNB. In some examples, a remote WTRU may request a single-hop relay service to connect to a WTRU-to-WTRU (U2U) relay. A U2U relay may be connected to another WTRU.

[0128] A WTRU may request a multi-hop relay service, which may allow the WTRU to connect to, for example, a WTRU-to-WTRU (W2W) relay. A W2W relay may connect to a network via a W2N relay. A WTRU may implicitly and / or explicitly indicate that it is requesting to connect to a W2W relay. For example, a WTRU may implicitly and / or explicitly indicate in a discovery-relay-service message that it is requesting to connect to a W2W relay. A remote WTRU may request a multi-hop relay service, which may allow a WTRU (e.g., another WTRU) to connect to, for example, a U2U relay. A U2U relay may connect to a network via a WTRU-to-network (U2N) relay. Alternatively or additionally, a WTRU may send a discovery-service message, which may implicitly and / or explicitly indicate that the WTRU is requesting to connect to a U2U relay. A remote WTRU may request a relay service without requesting a single-hop relay service or a multi-hop relay service. The WTRU may connect to one or more of a single-hop relay service and a multi-hop relay service (eg, after requesting a relay service).

[0129] A WTRU may request a relay service regardless of single hop or multi-hop. A WTRU may connect to a single hop relay and / or a multi-hop relay service. A remote WTRU may request an L2 relay service, for example, in a discovery-relay-service message. A remote WTRU may receive (e.g., expect to receive) an SLRB configuration for an L2 relay service from a gNB and / or a relay WTRU.

[0130] The WTRU may request L2 relay service in the discovery-relay-service message. The WTRU may expect to receive SLRB configuration for L2 relay service from the gNB and / or relay WTRU.

[0131] The WTRU may request L3 relay service in the discovery-relay-service message. In some examples, the WTRU may not expect to receive SLRB configuration for relay service from the gNB and / or relay WTRU.

[0132] The WTRU may perform discovery-relay-service message sending. For example, a WTRU (e.g., a relay WTRU) may send a discovery-relay-service message (e.g., a discovery-relay-service announcement). The discovery-relay-service message may be used to provide one or more of the following relay services to a remote WTRU: a single-path relay service, a multi-path relay service, a single-hop relay service, a multi-hop relay service, a layer 2 relay service, and / or a layer 3 relay service. In another example, a WTRU (e.g., a remote WTRU) may send a discovery-relay-service message (e.g., a discovery-relay-service request message). The discovery-relay-service message may be used to request a relay service from one or more relay WTRUs. Additionally or alternatively, the WTRU may request one or more of the following relay services from one or more relay WTRUs: a single-path relay service, a multi-path relay service, a single-hop relay service, a multi-hop relay service, a layer 2 relay service, and / or a layer 3 relay service. As described herein, a discovery-relay-service message may be used for one or more of a discovery-relay-service advertisement, a discovery-relay-service request, and / or a discovery-relay-service response message.

[0133] Network-scheduled discovery transmissions may be performed. The WTRU may receive a (pre)configuration for discovery-relay-service transmissions. The WTRU may be (pre)configured with one or more parameters and / or conditions for discovery-relay-service transmissions. For example, the WTRU may receive a configuration from the network via a SIB and / or a dedicated RRC message. Additionally or alternatively, for one or more types of discovery-relay-service messages, the WTRU may be preconfigured with one or more of the following parameters and / or conditions for discovery-relay-service transmissions: Uu RSRP; resource pool and / or resource pool type for sending a type of discovery-relay-service message; parameters for discovery-relay-service transmissions; and / or minimum Uu RSRP for relays and / or minimum SL-RSRP / SD-RSRP for SLRB / LCH.

[0134] The parameters and / or conditions for the discovery-relay-service transmission may include Uu RSRP. The parameters and / or conditions for the discovery-relay-service transmission may include Uu RSRP ranges for one or more (e.g., each) type of discovery-relay-service messages, as described herein. For example, a WTRU (e.g., a relay WTRU) may be (pre)configured with a minimum Uu RSRP to send a multipath discovery-relay-service message. For example, if the measured Uu RSRP is greater than a configured minimum Uu RSRP threshold (e.g., min_Uu_RSRP), the WTRU may send a multipath discovery-relay-service message. In some scenarios, if the measured Uu RSRP is less than min_Uu_RSRP, the WTRU may not send a multipath discovery-relay-service message. In another example, a WTRU (e.g., a remote WTRU) may be (pre)configured with a Uu RSRP range (e.g., min_Uu_RSRP and max_Uu_RSRP). The Uu RSRP range may be used to send a multipath discovery-relay-service message. For example, if the measured Uu RSRP is within the configured Uu RSRP range, the WTRU may send a multipath discovery-relay-service message. In some scenarios, if the measured Uu RSRP is outside the configured range, the WTRU may not send a multipath discovery-relay-service message.

[0135] The parameters and / or conditions for the discovery-relay-service transmission may include a resource pool and / or resource pool type for sending a type of discovery-relay-service message. For example, the WTRU may be (pre)configured with a dedicated resource pool to send multipath discovery-relay-service messages. For example, the WTRU may be (pre)configured with a shared resource pool set to send multipath discovery-relay-service messages.

[0136] The parameters and / or conditions for discovery-relay-service transmission may include parameters for discovery-relay-service transmission. For example, these parameters may include one or more of the range transmission power, MCS, number of subchannels, number of retransmissions, and / or transmission periodicity of each discovery-relay-service message (e.g., multipath discovery-relay-service message).

[0137] The parameters and / or conditions for the discovery-relay-service transmission may include the minimum Uu RSRP of the relay and / or the minimum SL-RSRP / SD-RSRP of the SLRB / LCH. For example, for one or more SLRB / LCHs used for a multipath relay service, the WTRU (e.g., a remote WTRU or a relay WTRU) may be (pre)configured with the minimum Uu RSRP and / or minimum SL-RSRP / SD-RSRP of the relay WTRU to establish the multipath relay service. For example, for the SLRB / LCH associated with the multipath relay service, if the Uu RSRP of the relay is greater than or equal to a threshold and / or the SL-RSRP / SD-RSRP is greater than another threshold, the WTRU may establish a multipath connection with the relay.

[0138] The WTRU may indicate to the network its supported relay service capabilities. For example, the WTRU may indicate to the network whether it supports one or more of the following relay services: single-path, multi-path, single-hop, multi-hop, layer 2 and / or layer 3 relay services.

[0139] The WTRU may receive an indication from the network indicating which type of relay the WTRU should act as. The WTRU may (eg, then) perform sending / receiving of a discovery-relay-service message associated with the relay type indicated by the network.

[0140] The WTRU may request resources for discovery resources. The WTRU may trigger a discovery-relay-service transmission for a type of discovery-relay-service message. The WTRU may (e.g., then) request sidelink resources from the network for (e.g., such) transmission. The WTRU may indicate which type of discovery-relay-service message is to be sent (e.g., it wishes to send). For example, for each type of discovery-relay-service message, the WTRU may be (pre)configured with an LCG and / or a destination ID / destination index. The WTRU may (e.g., then) request the availability of discovery-relay-service data using the LCG and / or destination ID / index (e.g., via an SL BSR). The WTRU may (e.g., then) expect to receive sidelink resources to send that type of discovery-relay-service message.

[0141] A WTRU (e.g., a relay WTRU) may report a set of remote WTRUs (e.g., detected remote WTRUs). The set of remote WTRUs may include one or more remote WTRUs (e.g., one or more detected remote WTRUs). A WTRU (e.g., a relay WTRU) may monitor discovery messages (e.g., request messages) from one or more remote WTRUs. The WTRU may report the set of detected remote WTRUs, for example, after monitoring the discovery messages. The WTRU may be (pre)configured with an SD-RSRP threshold. The SD-RSRP threshold may be associated with the set of remote WTRUs (e.g., the reporting of the set of remote WTRUs). For example, if the SD-RSRP sent from the remote WTRU is greater than the (pre)configured threshold, the WTRU may report the set of detected remote WTRUs. The WTRU may be indicated in (e.g., each) request message (e.g., associated with one or more types of request relay services). For example, the WTRU may indicate whether the remote WTRU is requesting a single-path relay service, a multi-path relay service, a single-hop relay service, and / or a multi-hop relay service. For (e.g., each) reported remote WTRU, the WTRU may (e.g., then) send (e.g., indicate) to the network what type of relay service the remote WTRU is requesting. In some examples, the WTRU may report to the network a set of remote WTRUs requesting one type of relay service. For example, the WTRU may report a set of remote WTRUs requesting multipath relay service. For example, the WTRU may report a set of remote WTRUs requesting single-path relay service.

[0142] The relay WTRU may determine which set of detected remote WTRUs to report to the network. The WTRU (e.g., relay UE) may determine which set of detected remote WTRUs to report to the network based on one or more of the following. The WTRU may determine which set of detected remote WTRUs to report to the network based on the (pre)configured relay type. For example, the WTRU may report a detected set of remote WTRUs based on its (pre)configured relay type. For example, if the WTRU is (pre)configured with a multipath relay type, the WTRU may report a set of remote WTRUs requesting multipath service. For example, if the WTRU is (pre)configured with a single path relay service, the WTRU may only report a set of remote WTRUs requesting single path relay service.

[0143] The WTRU may determine which set of detected remote WTRUs to report to the network based on the Uu RSRP of the relay. For example, if the Uu RSRP satisfies the (pre)configured Uu RSRP threshold for being a multipath relay (e.g., the Uu RSRP is greater than the Uu RSRP threshold), the WTRU may report the set of remote WTRUs requesting multipath relay. Alternatively or additionally, if the UuRSRP satisfies the (pre)configured Uu RSRP threshold for being a single path relay (e.g., the Uu RSRP is greater than one Uu RSRP threshold and less than another Uu RSRP threshold), the WTRU may report the set of remote WTRUs requesting single path relay service. In another example, if the Uu RSRP satisfies the (pre)configured Uu RSRP threshold for both single path and multipath relay services, the WTRU may report all detected remote WTRUs requesting relay service (e.g., both single path and multipath).

[0144] The WTRU may report a set of relay WTRUs (e.g., detected relay WTRUs). The set of relay WTRUs may include one or more relay WTRUs (e.g., one or more detected relay WTRUs). A WTRU (e.g., a remote WTRU) may monitor one or more discovery messages from one or more relay WTRUs. The WTRU may (e.g., then) report the set of detected relay WTRUs. The WTRU may be (pre)configured with an SD-RSRP threshold. The SD-RSRP threshold may be associated with a set of relay WTRUs (e.g., reporting of a set of relay WTRUs). The WTRU may report the detected relay WTRUs. For example, if the SD-RSRP sent from the relay WTRU is greater than the (pre)configured threshold, the WTRU may report the detected relay WTRU. The WTRU may send (e.g., indicate) the type of relay service (e.g., providing relay service) in (e.g., each) discovery message. For example, the WTRU may send (e.g., indicate) whether the relay WTRU is providing a single-path relay service, a multi-path relay service, a single-hop relay service, and / or a multi-hop relay service. For (e.g., each) reported relay WTRU, the WTRU may (e.g., then) indicate to the network which type or types of relay services the relay WTRU is providing. In some examples, the WTRU may report to the network a set of relay WTRUs that provide one or more (e.g., one) types of relay services. For example, the WTRU may report a set of relay WTRUs that provide multipath relay services. For example, the WTRU may report a set of relay WTRUs that provide single-path relay services.

[0145] The WTRU may determine which set of relay WTRUs (e.g., detected relay WTRUs) to report to the network. The set of relay WTRUs may include one or more relay WTRUs (e.g., one or more detected relay WTRUs). The WTRU (e.g., a remote WTRU) may monitor one or more discovery-relay-service messages from one or more (e.g., multiple) relay WTRUs. The WTRU may (e.g., then) determine which set of detected relay WTRUs to report to the network based on one or more of the conditions in this document (e.g., below). The WTRU may determine which set of detected relay WTRUs to report to the network based on the (pre) configured relay type. For example, the WTRU may be (pre) configured to report detected relays of one type (e.g., relays that support multipath services). The WTRU may (e.g., then) report a set of relays (e.g., relays that support multipath services) that support the (pre) configured type.

[0146] The WTRU may determine which set of detected relay WTRUs to report to the network based on the Uu RSRP of the remote WTRU. For example, if the Uu RSRP of the WTRU is greater than a threshold, the WTRU may report the set of relay WTRUs that support multi-path service. In another example, if the Uu RSRP is less than a threshold, the WTRU may report all detected relays and / or relays that support single-path relay service.

[0147] The WTRU may determine which set of detected relay WTRUs to report to the network based on the WTRU's connection state (e.g., whether the WTRU is directly connected to the gNB via Uu or via U2N relay). In one example, when the WTRU is connected to the gNB via Uu, the WTRU may report the set of detected relays that support multi-path relays. In another example, when the WTRU is connected to the gNB via another relay, the WTRU may report all detected relays or the set of detected relays that support single-path relay service.

[0148] The WTRU may determine which set of detected relay WTRUs to report to the network based on the Uu RSRP of the relay WTRU. The Uu RSRP may be indicated in the discovery-relay-service message of the relay WTRU. For example, the WTRU may be (pre) configured to monitor one or more discovery-relay-service messages from the relay to request multipath service. In some examples, the WTRU may report a set of relays whose Uu RSRP is greater than a (pre) configured threshold. For example, the WTRU may be (pre) configured to monitor one or more discovery-relay-service messages from one or more relay WTRUs. The WTRU may be (pre) configured to monitor one or more discovery-relay-service messages from one or more relay WTRUs to request single-path relay service. The WTRU may report a set of relay WTRUs whose Uu RSRP is greater than or equal to a threshold and / or less than a threshold (e.g., a different threshold).

[0149] The WTRU may determine which set of detected relay WTRUs to report to the network based on, for example, the QoS of the established SLRB / LCH. For example, the WTRU may report relay WTRUs whose Uu RSRP is above a threshold. The threshold may be a function of the QoS of the established SLRB / LCH. For example, for a first established SLRB / LCH, the WTRU may report relay WTRUs whose Uu RSRP is greater than a first threshold. Additionally or alternatively, for a second established SLRB / LCH, the WTRU may report relay WTRUs whose Uu RSRP is greater than a second threshold.

[0150] The relay WTRU may indicate information in the discovery message. For example, the relay WTRU may indicate Uu information in the network. The relay WTRU may indicate Uu information in the network to support remote WTRUs in relay selection. The WTRU may indicate one or more Uu information as in (e.g., below) Uu information herein. The WTRU may indicate the distance to the gNB. Additionally or alternatively, the WTRU may indicate the location of the WTRU. For example, the WTRU may indicate whether the WTRU is at the cell edge or the cell center. In some examples, the WTRU may assume that when the relay is at the cell edge, it may support (e.g., either) single-path and / or multi-path relay services. Alternatively or additionally, when the relay WTRU is at the cell center, it may (e.g., only) support multi-path relay services.

[0151] The remote WTRU may indicate the connection status in the DISCOVERY-SERVICE message. For example, when the WTRU sends a DISCOVERY-REQUEST message, the WTRU may indicate one or more of the following parameters in the DISCOVERY-SERVICE-Message. The remote WTRU may indicate the Uu connection status (e.g., whether it is connected to the gNB and / or whether it is connected to the gNB via Uu and / or via another U2N relay). Alternatively or additionally, the remote WTRU may indicate the Uu RSRP. Alternatively or additionally, the remote WTRU may indicate the distance to the gNB.

[0152] The WTRU may request one or more resources for a discovery-relay-service transmission. For example, the WTRU may request sidelink resources for a discovery transmission (e.g., a request message or an announcement message). Alternatively or additionally, the WTRU may indicate to the network the relay service that the WTRU is providing / requesting. This method may help the network to appropriately schedule resources to the WTRU.

[0153] The WTRU may receive an indication for sending a discovery-relay-service message. For example, the network may send to the WTRU what type of relay service the WTRU needs to request / provide. For example, the network may indicate to the WTRU whether to request / provide single-path, multi-path, single-hop and / or multi-hop relay services. The WTRU may perform the sending of a discovery message, which includes the type of relay service that the WTRU is providing / requesting as indicated by the network. Alternatively or additionally, the WTRU may transmit to the network what type of relay service the WTRU needs to request / provide. For example, the WTRU may indicate to the network whether to request / provide single-path, multi-path, single-hop and / or multi-hop relay services.

[0154] The WTRU may report a set of detected remote WTRUs. In an example, a WTRU (e.g., a relay WTRU) may monitor discovery messages (e.g., request messages) from a remote WTRU. The WTRU may (e.g., then) report a set of detected remote WTRUs. The WTRU may be (pre)configured with an SD-RSRP threshold. Additionally or alternatively, the WTRU may report detected remote WTRUs. For example, if the SD-RSRP sent from the remote WTRU is greater than the (pre)configured threshold, the WTRU may report the detected remote WTRU. The type of relay service requested by the WTRU may be indicated in each request message. For example, the WTRU may be indicated based on whether the remote WTRU is requesting one or more relay services of a single-path relay service, a multi-path relay service, a single-hop relay service, and / or a multi-hop relay service. For each reported remote WTRU, the WTRU may (e.g., then) indicate to the network which type of relay service the remote WTRU is requesting. The WTRU may report to the network a set of remote WTRUs requesting a type of relay service. For example, a WTRU may report a set of remote WTRUs that request multi-path relay service.For example, a WTRU may report a set of remote WTRUs that request single-path relay service.

[0155] A relay WTRU may determine which set of remote WTRUs (e.g., detected remote WTRUs) to report to the network. The set of remote WTRUs may include one or more remote WTRUs (e.g., one or more detected remote WTRUs). A WTRU (e.g., a relay WTRU) may determine which set of detected remote WTRUs to report to the network based on one or more of the conditions herein (e.g., below). A WTRU (e.g., a relay WTRU) may determine which set of detected remote WTRUs to report to the network based on a (pre) configured relay type. For example, a WTRU may report a set of detected remote WTRUs based on its (pre) configured relay type. For example, if the WTRU is (pre) configured with a multipath relay type, the WTRU may report a set of remote WTRUs requesting multipath service. For example, if the WTRU is (pre) configured with a single path relay service, the WTRU may only report a set of remote WTRUs requesting a single path relay service.

[0156] A WTRU (e.g., a relay WTRU) may determine which set of detected remote WTRUs to report to the network based on the Uu RSRP of the relay. For example, if the Uu RSRP satisfies the (pre)configured Uu RSRP threshold for being a multipath relay (e.g., the Uu RSRP is greater than the Uu RSRP threshold), the WTRU may report the set of remote WTRUs requesting multipath relay. Alternatively or additionally, if the Uu RSRP satisfies the (pre)configured Uu RSRP threshold for being a single path relay (e.g., the Uu RSRP is greater than one Uu RSRP threshold and less than another Uu RSRP threshold), the WTRU may report the set of remote WTRUs requesting single path relay service. In another example, if the Uu RSRP satisfies the (pre)configured Uu RSRP threshold for both single path and multipath relay services, the WTRU may report all detected remote WTRUs requesting relay services (e.g., both single path and multipath).

[0157] The WTRU may report a detected set of relays. For example, a WTRU (e.g., a remote WTRU) may monitor discovery messages. The WTRU may monitor discovery messages from one or more relay WTRUs. The WTRU may (e.g., then) report a detected set of relay WTRUs. The WTRU may be (pre)configured with an SD-RSRP threshold. The WTRU may use the SD-RSRP threshold to report detected relay WTRUs. For example, if the SD-RSRP sent from the relay WTRU is greater than the (pre)configured threshold, the WTRU may report the detected relay WTRU. The WTRU may be indicated in one or more (e.g., each) discovery messages. For example, the type of relay service provided may be indicated in one or more (e.g., each) discovery messages. In some examples, the WTRU may indicate whether the relay WTRU is providing a single-path relay service, a multi-path relay service, a single-hop relay service, and / or a multi-hop relay service. (e.g., for each reported relay WTRU), the WTRU may then indicate (e.g., send / report) to the network which type of relay service the relay WTRU is providing. The WTRU may report (e.g., send a report message) to the network a set of relay WTRUs that provide one or more (e.g., one) type of relay service. For example, the WTRU may report a set of relay WTRUs that provide a multi-path relay service. For example, the WTRU may report a set of relay WTRUs that provide a single-path relay service.

[0158] The WTRU may determine which set of relay WTRUs (e.g., detected relay WTRUs) to report to the network. The set of relay WTRUs may include one or more relay WTRUs (e.g., one or more detected relay WTRUs). The WTRU (e.g., a remote WTRU) may monitor discovery-relay-service messages from one or more (e.g., multiple relays). The WTRU may (e.g., then) determine which set of detected remote WTRUs to report to the network based on one or more of the following. The WTRU may determine which set of detected relay WTRUs to report to the network based on (pre) configured relay types. For example, the WTRU may be (pre) configured to report one or more (e.g., one) types of detected relays (e.g., relays that support multipath services). The WTRU may (e.g., then) report a set of relays (e.g., relays that support multipath services) that support the (pre) configured types.

[0159] The WTRU may determine which set of detected relay WTRUs to report to the network based on the Uu RSRP of the remote WTRU. For example, if the Uu RSRP of a WTRU (e.g., of a relay WTRU) is greater than a threshold, the WTRU may report the set of relay WTRUs that support multi-path service. In another example, if the Uu RSRP of a WTRU is less than a threshold, the WTRU may report all detected relays or relays that support single-path relay service.

[0160] The WTRU may determine which set of detected relay WTRUs to report to the network based on the WTRU's connection state (e.g., whether the WTRU is directly connected to the gNB via Uu or via U2N relay). In one example, when the WTRU is connected to the gNB via Uu, the WTRU may report the set of detected relays that support multi-path relays. In another example, when the WTRU is connected to the gNB via another relay, the WTRU may report all detected relays or the set of detected relays that support single-path relay service.

[0161] The WTRU may determine which set of detected relay WTRUs to report to the network based on the Uu RSRP of the relay WTRU. The Uu RSRP of the relay WTRU may be indicated in the discovery-relay-service message of the relay WTRU. For example, the WTRU may be (pre)configured to monitor the discovery-relay-service message from the relay to request multi-path service. The WTRU may report a set of relays whose Uu RSRP is greater than a (pre)configured threshold. For example, the WTRU may be (pre)configured to monitor the discovery-relay-service message from the relay to request single-path relay service. The WTRU may report a set of relay WTRUs whose Uu RSRP is greater than (e.g., a first) threshold and / or less than another (e.g., a second) threshold.

[0162] The WTRU may determine which set of detected relay WTRUs to report to the network based on the QoS of the established SLRB / LCH. For example, the WTRU may report relay WTRUs whose Uu RSRP exceeds a threshold. The threshold may be a function of the QoS of the established SLRB / LCH. For example, for a first established SLRB / LCH, the WTRU may report relays whose Uu RSRP exceeds a first threshold. Additionally or alternatively, for a second established SLRB / LCH, the WTRU may report relays whose Uu RSRP is greater than a second threshold (e.g., a different threshold).

[0163] The WTRU may request one or more resources for discovery-relay-service transmission. In an example, the WTRU may request one or more sidelink resources for discovery transmission (e.g., request message and / or announcement message). The WTRU may also indicate (e.g., send) to the network the relay service that the WTRU is providing / requesting. The WTRU may help the network schedule one or more resources to the WTRU.

[0164] The WTRU may receive an indication for sending a discovery-relay-service message. In an example, the WTRU may receive an indication from a network. The indication may indicate which type of relay service the WTRU should request and / or provide. For example, the indication may indicate to the WTRU whether to request / provide single-path, multi-path, single-hop and / or multi-hop relay services. The WTRU may send one or more discovery messages. The one or more discovery messages may include the type of relay service that the WTRU is providing and / or requesting (e.g., as indicated by the network).

[0165] The WTRU may send one or more autonomous discovery messages. For example, the WTRU may determine to perform the sending of a discovery-relay-service message (e.g., sending a discovery-relay-service message). The WTRU may trigger the sending of a discovery-relay-service and / or relay (re)selection. For example, the WTRU may trigger the sending of a discovery-relay-service and / or relay (re)selection based on one or any combination of the following events / conditions: Uu RSRP has a (pre)configured range; relay load; indication from another node (e.g., gNB); reception of an SLRB / LCH configuration (e.g., including at least one SLRB / LCH requiring multipath relay service); arrival of data from a set of SLRB / LCHs in a buffer; an amount of data from a set of SLRB / LCHs greater than or equal to a threshold; reception of a discovery-relay message from another WTRU; a CBR of a resource pool associated with the sending of the discovery-relay message is less than a threshold; and / or a distance to the gNB is within a configured range.

[0166] The WTRU may trigger a discovery-relay-service transmission and / or relay (re)selection based on a Uu RSRP with a (pre)configured range. For example, the WTRU may be (pre)configured with a Uu-RSRP range (e.g., min_Uu_RSRP and / or max_Uu_RSRP) to send a discovery-relay-service message. In some examples, the WTRU may trigger a discovery-relay-service transmission if the measured Uu-RSRP is within the (pre)configured range. In other examples, the WTRU may not send a message if the measured Uu-RSRP is outside the (pre)configured range.

[0167] The WTRU may trigger discovery-relay-service sending and / or relay (re)selection based on relay load. For example, a WTRU (e.g., a relay WTRU) may be (pre)configured with a relay load range (e.g., to send a discovery-relay-service message). For example, if the WTRU's load is within the (pre)configured range, the WTRU may (e.g., then) send a discovery-relay-service message.

[0168] The WTRU may trigger a discovery-relay-service transmission and / or relay (re)selection based on an indication from another node (e.g., a gNB). For example, another node (e.g., a gNB) may instruct and / or request the WTRU to perform a discovery-relay-service transmission. The WTRU may (e.g., then) send a discovery-relay-service message (e.g., based on the request and / or indication from the node).

[0169] The WTRU may trigger discovery-relay-service transmission and / or relay (re)selection, for example, based on (e.g., receiving) a SLRB / LCH configuration. The SLRB / LCH configuration may include one or more SLRB / LCHs for which a multipath relay service is requested. For example, the WTRU may receive a SLRB / LCH configuration from another node (e.g., a gNB), which may include one or more SLRB / LCHs for which a multipath relay service is requested (e.g., SLRB / LCHs whose priority and / or reliability is greater than or equal to a threshold). The WTRU may (e.g., then) trigger discovery-relay-service transmission. The WTRU may send a discovery-relay-service message, which may, for example, request a multipath relay service.

[0170] The WTRU may trigger a discovery-relay-service transmission and / or relay (re)selection based on the arrival of data from the set of SLRB / LCHs in the buffer. For example, a WTRU (e.g., a remote WTRU) may be (pre)configured with one or more SLRB / LCHs for a multipath relay service. The WTRU may (e.g., then) trigger the transmission of a discovery-relay-service message. The discovery-relay-service message may request a multipath relay service.

[0171] The WTRU may trigger a discovery-relay-service transmission and / or relay (re)selection based on the amount of data from the SLRB / LCH set being greater than or equal to a threshold. For example, a WTRU (e.g., a remote WTRU) may be (pre)configured with one or more SLRB / LCHs for a multipath relay service. The WTRU may be (pre)configured with a minimum amount of data from the SLRB / LCH set for multipath relay to trigger a discovery-relay-service transmission. If the amount of data in the SLRB / LCH set is greater than or equal to a threshold, the WTRU may then trigger a discovery-relay-service message transmission, which may request a multipath relay service. The threshold may be (pre)configured.

[0172] The WTRU may trigger discovery-relay-service transmission and / or relay (re)selection based on the amount of data from the SLRB / LCH set being greater than (e.g., exceeding) a threshold. For example, a WTRU (e.g., a remote WTRU) may be (pre)configured with one or more SLRB / LCHs for a multipath relay service. The WTRU may be (pre)configured with, for example, a minimum amount of data from a SLRB / LCH set for multipath relay to trigger discovery-relay-service transmission. The WTRU may (e.g., then) trigger the transmission of a discovery-relay-service message. The discovery-relay-service message may include a request for a multipath relay service. For example, if the amount of data in the SLRB / LCH set is greater than or equal to a threshold, the discovery-relay-service message may include a request for a multipath relay service. The threshold may be (pre)configured.

[0173] The WTRU may trigger discovery-relay-service transmission and / or relay (re)selection based on receiving a discovery-relay message from another WTRU. For example, the WTRU may determine whether to send a discovery message based on receiving a discovery message that provides (e.g., the same) relay service. For example, the WTRU may monitor one or more discovery messages from one or more other relay WTRUs. The WTRU may determine whether to send a discovery message based on whether the WTRU receives, for example, (e.g., any) discovery message (e.g., providing the same type of relay service) whose SD-RSRP is greater than or equal to a threshold. In some examples, if the WTRU detects a discovery message that provides the same relay service and whose SD-RSRP is greater than a (pre)configured threshold, the WTRU may not send a discovery message. In other examples, the WTRU may send a discovery message (e.g., in other ways).

[0174] The WTRU may trigger discovery-relay-service sending and / or relay (re)selection based on the CBR of the resource pool being less than a threshold. For example, the CBR of the resource pool may be associated with the discovery-relay message. The WTRU may be (pre)configured with a dedicated resource pool, for example, for sending one or more types of discovery messages for one or more types of relay services. For example, if the CBR of the resource pool is less than a threshold, the WTRU may determine to send a discovery-relay-service message. In other examples (e.g., otherwise), the WTRU may not send a discovery message.

[0175] The WTRU may trigger a discovery-relay-service transmission and / or relay (re)selection based on the distance to the gNB. For example, the WTRU may trigger a discovery-relay-service transmission and / or relay (re)selection based on the distance to the gNB being within a configured range. For example, a WTRU (e.g., a relay WTRU) may determine whether to send a discovery relay message based on the distance to the gNB. In some examples, the WTRU may be (pre)configured with a range of distances to the gNB, for example to send a multipath discovery-relay-service message. In some examples, the WTRU may trigger a discovery transmission if the distance between the WTRU and the gNB is within a (pre)configured range.

[0176] The WTRU may determine to send (e.g., send) one or more discovery-relay-service messages (e.g., discovery-relay-service messages). For example, the WTRU (e.g., relay WTRU) may be (pre)configured with a Uu RSRP range (e.g., [Uu RSRP threshold 1, Uu RSRP threshold 2]). The Uu RSRP range may be associated with sending a discovery-relay-service message. In one example, if the WTRU supports single-path relay service, the WTRU may send a discovery-relay-service message if the WTRU's Uu RSRP is within the range. In another example, if the WTRU supports multi-path relay service, the WTRU may ignore the upper limit of the (pre)configured Uu RSRP threshold range and send a discovery-relay-service message. For example, if the Uu RSRP is greater than the Uu RSRP threshold (e.g., Uu RSRP>Uu RSRP threshold 1), the WTRU may send a discovery-relay-service message.

[0177] The WTRU may determine whether a cell supports one or more relay services (e.g., one relay service). For example, the WTRU may determine whether a cell supports a certain relay service (e.g., a multipath relay service). The WTRU may receive a SIB. The SIB may implicitly / explicitly indicate whether a relay service is supported (e.g., the SIB may implicitly / explicitly indicate whether a multipath relay service is supported).

[0178] The WTRU may determine whether to send one or more discovery-relay-service messages (e.g., discovery-relay-service message), for example, based on one or more indications from the cell. For example, the WTRU may be (pre)configured with a Uu RSRP range (e.g., [Uu RSRP threshold 1, Uu RSRP threshold 2]). The Uu RSRP range may be associated with sending a discovery-relay-service message. The Uu RSRP of the WTRU may exceed a second Uu RSRP threshold (e.g., Uu RSRP threshold 2). The WTRU may (e.g., then) determine whether to send a discovery message based on whether the cell supports multipath relay service. For example, if the cell supports multipath relay service, the WTRU may send a discovery-relay-service message. In another example, if the cell does not support multipath relay service, the WTRU may not send a discovery-relay-service message.

[0179] The WTRU may determine whether to respond to the remote WTRU. The WTRU (e.g., a relay WTRU) may perform one or more of the actions as described herein (e.g., below), for example, upon detecting / receiving a discovery-relay-service message, to respond to the remote WTRU. The WTRU (e.g., a relay WTRU) may perform resource allocation and / or send a response message to the remote WTRU. In another example, the WTRU (e.g., a relay WTRU) may request sidelink resources to respond to the remote WTRU. Additionally or alternatively, the WTRU (e.g., a relay WTRU) may report the detected remote WTRU to the network.

[0180] A relay WTRU supporting multipath relay service may determine whether to respond to a remote WTRU based on one or more of the conditions as described herein (e.g., below). A relay WTRU may determine whether to respond to a remote WTRU based on the Uu RSRP of the WTRU. For example, the WTRU may be (pre)configured with a Uu RSRP threshold to act as a multipath relay. For example, if the Uu RSRP exceeds the threshold, the WTRU may respond to the remote WTRU. In another example, if the Uu RSRP does not exceed the threshold, the WTRU may not respond to the remote WTRU.

[0181] The relay WTRU may determine whether to respond to the remote WTRU based on one or more types of requested relay services. For example, the WTRU may not respond to the remote WTRU requesting a single-path relay service. The WTRU may respond to the remote WTRU requesting a multi-path relay service. Additionally or alternatively, the relay WTRU may determine whether to respond to the remote WTRU based on whether the cell supports a multi-path relay service. For example, the WTRU may not respond to the remote WTRU requesting a multi-path service. For example, if the relay WTRU supports both multi-path and single-path relay services, the WTRU may respond to the remote WTRU requesting a single-path relay service.

[0182] The WTRU may determine to send (e.g., which) discovery-relay-service message. For example, a WTRU (e.g., a relay WTRU) may determine to send (e.g., send) a discovery-relay-service message. The WTRU may determine which type of discovery-relay-service message to send (e.g., send) based on one or more of: measured Uu RSRP; relay load; relay capabilities; requested relay services; expected relay services to be supported; an indication from another node (e.g., a gNB); a priority associated with each discovery-relay-service message; a predefined order of sending each discovery service message; and / or a distance to the gNB.

[0183] The WTRU may determine which type of discovery-relay-service message to send based on the measured Uu RSRP. In some examples, a WTRU (e.g., a relay WTRU) may be (pre)configured with a Uu RSRP range (e.g., min_Uu_RSRP and / or max_Uu_RSRP), for example, to send (e.g., each) type of discovery-relay-service message. For example, the WTRU may be pre-configured with and / or receive (e.g., via RRC and / or SIB) one or more (e.g., two) ranges of Uu RSRP thresholds. A first range (e.g., of Uu RSRP thresholds) may be associated with a single-path relay service, and / or a second range (e.g., of Uu RSRP thresholds) may be associated with a multi-path relay service. The WTRU may (e.g., then) determine to send (e.g., which) discovery-relay-service message based on whether the Uu RSRP is within (e.g., within which) (pre)configured range. For example, the WTRU may be (pre)configured with two Uu RSRP ranges, one of which may be associated with a single-path relay service and the other of which may be associated with a multi-path relay service. For example, if the Uu RSRP is within the range (pre)configured for single-path relay, the WTRU may (e.g., then) determine to send (e.g., send) a single-path discovery-relay-service message. For example, if the measured Uu RSRP is within the range (pre)configured for multi-path relay service, the WTRU may determine to send a multi-path discovery-relay-service message. In some examples, if the WTRU meets two Uu RSRP ranges (e.g., a first range and a second range), the WTRU may send a prioritized discovery-relay-service message. The WTRU may (pre)configure which type of discovery-service message is prioritized. For example, the WTRU may be (pre)configured to prioritize single-path-discovery-service messages. Alternatively or additionally, the WTRU may be (pre)configured to prioritize multi-path discovery-service messages. In some examples, the WTRU may send a discovery-service message that may implicitly and / or explicitly indicate that the WTRU supports both single-path and multi-path relay services.

[0184] For example, a WTRU (e.g., a remote WTRU) may be (pre)configured with one or more (e.g., two) ranges of Uu RSRP thresholds, wherein a first range may be associated with a request for a single-path relay service and / or a second range may be associated with a request for a multi-path relay service. The WTRU may (e.g., then) determine which request message to send based on whether the Uu RSRP is within the first range and / or the second range of the Uu RSRP. In some examples, if the Uu RSRP is within the first range, the WTRU may send a request for a single-path relay service, and / or if the Uu RSRP is within the second range, the WTRU may send a request message for a multi-path relay service. In some examples, if the Uu RSRP satisfies both ranges, the WTRU may send a request message that takes precedence. Alternatively or additionally, if the Uu RSRP satisfies both ranges, the WTRU may send, for example, a request message requesting (e.g., either) a single-path and / or a multi-path relay service.

[0185] The WTRU may determine which type of discovery-relay-service message to send based on the relay load. The WTRU (e.g., a relay WTRU) may be (pre)configured with one or more (e.g., two) relay load ranges, for example, to send discovery-relay-service messages. (e.g., one) relay load range may be used for single-path relaying, and / or one (e.g., another) relay load range may be used for multi-path relay services. If the relay load is within a first relay load range, the WTRU may send, for example, a single-path discovery-relay-service message. In other examples (e.g., otherwise), if the relay load is within a second relay load range, the WTRU may send a multi-path discovery-relay-service message.

[0186] The WTRU may determine which type of discovery-relay-service message to send based on the relay (e.g., relay WTRU) capabilities. For example, the WTRU (e.g., relay WTRU) may determine which discovery-relay-service message to send based on its relay capabilities. In some examples, the WTRU may meet conditions for sending multiple types of discovery-relay-service messages. The WTRU (e.g., then) may determine to send (e.g., which) message based on its capabilities. For example, the WTRU may meet conditions for sending (e.g., either) single-path and / or multi-path discovery-relay-service messages. For example, if the WTRU (e.g., only) supports single-path relay service, the WTRU (e.g., then) may send a single-path discovery-relay-service message. In other examples (e.g., otherwise), if the WTRU (e.g., only) supports multi-path relay service, the WTRU may send a multi-path discovery-relay-service message.

[0187] The WTRU may determine which type of discovery-relay-service message to send based on the requested relay service. In some examples, the WTRU may send a multipath discovery-relay-service message, for example, if the WTRU is requested (e.g., from another node or from the WTRU's application layer) to perform multipath discovery-relay-service message sending.

[0188] The WTRU may determine which type of discovery-relay-service message to send based on the expected relay service to be supported. For example, the WTRU may determine which relay service to support. The WTRU may (e.g., then) determine which discovery-relay-service message to send, for example, based on the relay service that the WTRU determines (e.g., wishes) to support. In some examples, the WTRU may determine to support (e.g., become) a single-path relay, and / or the WTRU may (e.g., then) send a single-path discovery-relay-service message. In other examples, the WTRU may determine to support (e.g., become) a multi-path relay, and / or the WTRU may (e.g., then) send a multi-path discovery-relay-service message.

[0189] The WTRU may determine which type of discovery-relay-service message to send, for example, based on an indication and / or request from another node (e.g., a gNB). In some examples, the WTRU may (e.g., first) indicate to the network its supported relay capabilities. The WTRU may (e.g., then) receive an indication from the network. The indication may indicate which relay service(s) to support. The WTRU may (e.g., then) determine which discovery-relay-service message to send based on, for example, an indication from the network of which relay service to support.

[0190] The WTRU may determine which type of discovery-relay-service message to send based on a priority associated with (e.g., each) discovery-relay-service message. For example, the WTRU may be (pre)configured with a priority associated with (e.g., each) discovery-relay-service message. In some examples, if the WTRU meets the conditions for sending multiple discovery-relay-service messages, the WTRU may determine to send (e.g., send) a discovery message with a higher priority. For example, the WTRU may be (pre)configured so that a single-path relay service message has a higher priority than a multi-path relay service message. If the conditions for sending single-path and multi-path discovery-relay-service messages are met, the WTRU may (e.g., then) determine to send a single-path discovery-relay-service message. For example, the WTRU may be (pre)configured so that a multi-path relay service message has a higher priority than a single-path relay service message. If the conditions for sending a multi-path discovery-relay-service message are met, the WTRU may (e.g., then) determine to send a multi-path discovery-relay-service message.

[0191] The WTRU may determine which type of discovery-relay-service message to send based on a predefined order of sending each discovery service message. For example, if other conditions for sending multiple discovery-relay-services are met, the WTRU may be (pre)configured with the order of sending (e.g., each) discovery-relay-service message. In some examples, if the WTRU meets the conditions for sending single-path and / or multi-path discovery-relay-service messages (e.g., both), the WTRU may send a single-path discovery-relay-service message. For example, if the WTRU meets the conditions for sending single-hop and / or multi-hop discovery-relay-service messages (e.g., both), the WTRU may send a multi-hop discovery-relay-service message.

[0192] The WTRU may determine which type of discovery-relay-service message to send based on the distance to the gNB. For example, the WTRU may be (pre-)configured with one or more (e.g., multiple) ranges of distances to the gNB. (e.g., each) range may be associated with a type of relay-service-message (e.g., one range may be associated with single-path relay-service messages and another range may be associated with multi-path relay-service messages). The WTRU may (e.g., then) determine (e.g., which) relay-service-message to send based on the distance to the gNB.

[0193] Figure 4 An example system 400 is illustrated that illustrates a WTRU determining whether to send a single path discovery versus (eg, and / or) a multipath discovery and a single path request versus a multipath request. Figure 4As shown, the relay WTRU 406 may determine whether to send a single path and (e.g., and / or) a multipath discovery service message based on the Uu RSRP. Additionally or alternatively, the remote WTRU 402 may determine whether to send a single path request message and (e.g., and / or) a multipath request message based on the Uu RSRP. For example, if the UuRSRP is greater than the Uu RSRP threshold 1 (e.g., a first threshold), the relay WTRU 406 may send a multipath discovery message, and / or if the Uu RSRP is between the Uu RSRP threshold 1 (e.g., a first threshold) and the Uu RSRP threshold 2 (e.g., a second threshold), the relay WTRU 404 may determine to send (e.g., send) a single path discovery. The Uu RSRP threshold 2 (e.g., a second threshold) may be used to indicate a coverage boundary. The remote WTRU 408 may send one or more request messages for multipath. For example, the remote WTRU 408 may send one or more request messages for multipath if its Uu RSRP is greater than Uu RSRP threshold 2 (e.g., a second threshold), and / or the remote WTRU 402 may send one or more single path request messages if its Uu RSRP is less than Uu RSRP threshold 2 (e.g., a second threshold) and greater than Uu RSRP threshold 3 (e.g., a third threshold). The remote WTRU 402 and the remote WTRU 408 may be the same WTRU, e.g., moved farther away or closer to the gNB 410. The relay WTRU 406 and the relay WTRU 404 may be the same WTRU, e.g., moved farther away or closer to the gNB 410.

[0194] The WTRU may determine a QoS (e.g., priority) associated with a discovery-relay-service message. The QoS (e.g., priority of the discovery message) may be determined based on one or more of the (pre-)configuration of the discovery-relay-service message, the resource pool, and / or the resource pool type (e.g., shared versus dedicated). For example, the WTRU may be (pre-)configured with a priority associated with each type of discovery-relay-service message. The WTRU may (e.g., then) determine the priority of the message, for example, based on the type of discovery-relay-service message sent by the WTRU. In some examples, the WTRU may be (pre-)configured with a priority associated with one or more single-path discovery-relay-service messages and / or another priority associated with one or more multi-path discovery-relay-service messages. The WTRU may (e.g., then) determine the priority of the discovery message, for example, based on whether the discovery-relay-service message indicates a single path or a multi-path. In another example, the WTRU may be (pre)configured with one or more (e.g., two) priorities for the multipath discovery-relay-service message, for example, based on whether the discovery-relay-service message is sent in a shared and / or dedicated resource pool. For example, if the message is sent in a dedicated resource pool, the WTRU may use one priority (e.g., a first priority). If the message is sent in a shared resource pool, the WTRU may use another priority (e.g., a second priority).

[0195] The WTRU may determine one or more resource pools to send a discovery-relay-service message. For example, the WTRU may be (pre)configured with one or more dedicated resource pools for discovery messages and / or a shared resource pool for other sidelink data transmissions to send a discovery-relay-service message.

[0196] The WTRU may determine which resource pool and / or which type of resource pool (e.g., a dedicated resource pool or a shared resource pool) to use to send a discovery-relay-service message, for example based on one or more of the following: the type of the discovery-relay-service message; the QoS of the discovery-relay-service message; and / or the CBR of the resource pool.

[0197] The WTRU may determine which resource pool and / or which type of resource pool (e.g., a dedicated resource pool or a shared resource pool) to use for sending a discovery-relay-service message based on the type of discovery-relay-service message. For example, the WTRU may be (pre)configured with one or more resource pools to send a discovery-relay-service message. Additionally or alternatively, the WTRU may be (pre)configured with one or more resource pools to send (e.g., each type of) discovery-relay-service message. The WTRU may (e.g., then) determine which resource pool to use for sending a discovery-relay-service message, for example, based on the type of discovery message the WTRU is sending. For example, the WTRU may be (pre)configured to use a dedicated resource pool for a single-path discovery-relay-service message. The WTRU may be (pre)configured to use a multipath discovery-relay-service resource pool for a WTRU multipath discovery-relay-service message. The WTRU may (e.g., then) determine which type of resource pool to use for sending based on the type of discovery-relay-service message the WTRU is sending. For example, the WTRU may use a dedicated resource pool for single path discovery messages and / or may use a shared resource pool for multi-path discovery messages.

[0198] The WTRU may determine which resource pool and / or which type of resource pool (e.g., a dedicated resource pool or a shared resource pool) to use for sending a discovery-relay-service message based on the QoS of the discovery-relay-service message. For example, the WTRU may be (pre)configured with one or more priorities (e.g., a set of priorities) to send a discovery message in (e.g., one) type of resource pool. The WTRU may (e.g., then) determine which resource pool to use for sending a discovery message based on, for example, a priority associated with the discovery message. In some examples, the WTRU may be (pre)configured to use a dedicated resource pool for discovery transmissions with a priority of one (e.g., the highest priority). The WTRU may be (pre)configured to use a shared resource pool for discovery transmissions with another priority (e.g., a priority value greater than one / lower priority). For example, if the priority of the resource pool is one, the WTRU may (e.g., then) determine to send (e.g., send) the discovery message in the dedicated resource pool. In some examples (e.g., otherwise), the WTRU may send the discovery message in the shared resource pool.

[0199] The WTRU may determine which resource pool and / or which type of resource pool (e.g., a dedicated resource pool or a shared resource pool) to use for sending a discovery-relay-service message based on the CBR of the resource pool. For example, the WTRU may be (pre)configured to use (e.g., either) a shared resource pool and / or a dedicated resource pool to send (e.g., one) type of discovery message. Additionally or alternatively, if the CBR of the resource pool is less than a threshold, the WTRU may be (pre)configured to use a dedicated resource pool. In some examples (e.g., otherwise), the WTRU may use a shared resource pool. The WTRU may (e.g., then) determine whether to use a dedicated resource pool and / or a shared resource pool based on the CBR of the dedicated resource pool. For example, if the CBR of the resource pool is less than a threshold, the WTRU may use a dedicated resource pool. In another example (e.g., otherwise), if the CBR of the dedicated resource pool is greater than or equal to a threshold, the WTRU may use a shared resource pool. The CBR threshold may be (pre)configured in the dedicated resource pool.

[0200] The WTRU may determine one or more transmission parameters of a discovery-relay-service message. For example, the WTRU may determine one or more of the following discovery-relay-service message transmission parameters: MCS; transmit power; number of subchannels to use for one or more (e.g., each) transmissions; minimum, actual, and / or maximum number of retransmissions of one or more (e.g., each) messages; and / or the frequency of discovery-relay-service transmissions (e.g., discovery transmission periodicity).

[0201] One or more of the discovery-relay-service message sending parameters may be determined based on one or more of: the type of discovery-relay-service message; the sending resource pool of the discovery-relay-service message; the QoS associated with the discovery message; and / or the CBR of the resource pool.

[0202] One or more of the discovery-relay-service message transmission parameters may be determined based on the type of discovery-relay-service message. For example, the WTRU may be (pre)configured with one or more ranges of one or more transmission parameters for one or more (e.g., each) type of discovery-relay-service message. The WTRU may (e.g., then) determine the transmission parameters for the discovery-relay-service message, for example, based on the type of the discovery-relay-service message. In another example, the WTRU may be (pre)configured with one or more (e.g., each) type of discovery-relay-service message transmission power levels. The WTRU may (e.g., then) determine which transmission power level to use based on the type of the discovery-relay-service message.

[0203] One or more of the discovery-relay-service message transmission parameters may be determined based on the resource pool in which the discovery-relay-service message is transmitted. For example, the WTRU may be (pre-)configured with a range of one or more parameters for the discovery-relay-service transmission for each resource pool. The WTRU may (e.g., then) determine the transmission parameters of the discovery-relay-service message, for example, based on the resources used to transmit the message.

[0204] One or more of the discovery-relay-service message transmission parameters may be determined based on the QoS associated with the discovery message. For example, the WTRU may be (pre)configured with (e.g., one) QoS parameter (e.g., priority) for each type of discovery message. The WTRU may be (pre)configured with a range of one or more transmission parameters for discovery messages in a resource pool based on the QoS (e.g., priority) of the message. The WTRU may (e.g., then) determine the transmission parameters for the discovery-relay-service message based on the associated QoS (e.g., priority) of the discovery-relay-service message.

[0205] The WTRU may determine information to include in one or more discovery messages. For example, the WTRU may determine to include in the discovery message one or more of the following: the type of discovery-relay-service message; the SLRB / LCH set and / or QoS to be supported; the maximum and / or minimum data rate; the measured Uu RSRP; the type of node (e.g., relay node vs. remote node); the minimum Uu RSRP and / or the minimum SL-RSRP / SD-RSRP; the coverage status of the WTRU; and / or the WTRU's serving cell / gNB.

[0206] The WTRU may determine the type of discovery-relay-service message to include (e.g., send) in the discovery message. For example, the WTRU (e.g., a relay WTRU) may indicate the type of discovery-relay-service message in the message. The WTRU may implicitly and / or explicitly indicate in the discovery-relay-service message what type of relay service the WTRU is providing. For example, the WTRU may indicate whether it is supporting a single-path relay service, a multi-path relay service, a single-hop relay service, and / or a multi-hop relay service. In another example, the WTRU (e.g., a remote WTRU) may indicate the type of discovery-relay-service in the message. The WTRU may implicitly and / or explicitly indicate what type of relay service the WTRU is requesting. For example, the WTRU may indicate whether it is requesting a single-path relay service, a multi-path relay service, a single-hop relay service, and / or a multi-hop relay service.

[0207] The WTRU may determine to include in the discovery message the set of SLRB / LCHs and / or QoS to be supported. For example, the remote WTRU may indicate the SLRB / LCH and / or QoS of the data to be supported for the multipath service. The WTRU may indicate the QoS (e.g., priority, reliability, latency) of the data that triggers the discovery-relay-service transmission. In another example, the relay WTRU may indicate the SLRB / LCH and / or QoS of the data to be supported for the multipath service. The WTRU may indicate the QoS (e.g., priority, reliability, latency) of the data that the relay WTRU may support.

[0208] The WTRU may determine to include (e.g., send) a maximum and / or minimum data rate in a discovery message. For example, a remote WTRU may indicate its required maximum and / or minimum data rate in a discovery message, for example to support a relay WTRU responding to its discovery-relay-service message. In another example, a relay WTRU may indicate its supported maximum and / or minimum data rate in a discovery message. The discovery message may be used for the remote WTRU to perform relay (re)selection. The relay WTRU may indicate the current and / or instantaneous data rate, for example for an active relay connection at the time the discovery message is sent. The current and / or instantaneous data rate information may be used by the remote WTRU (e.g., in conjunction with) the maximum and / or minimum data rate supported by the relay WTRU when performing relay (re)selection.

[0209] The WTRU may determine to include (e.g., send) the measured Uu RSRP in a discovery message. For example, a WTRU (e.g., a relay WTRU) may indicate the measured Uu RSRP of the WTRU in a discovery-relay-service message. The measured Uu RSRP may be used to support a remote WTRU in relay (re)selection.

[0210] The WTRU may determine the type of node (eg, relay node versus remote node) included in the discovery message. For example, the WTRU may indicate whether it is a relay WTRU or a remote WTRU.

[0211] The WTRU may determine to include a minimum Uu RSRP and / or a minimum SL-RSRP / SD-RSRP in a discovery message. For example, a WTRU (e.g., a remote WTRU) may indicate a minimum Uu RSRP and / or a minimum SL-RSRP / SD-RSRP in a discovery-relay-service message, for example, to establish a multipath relay connection.

[0212] The WTRU may determine to include the coverage status of the WTRU in the discovery message. For example, the remote WTRU may indicate whether the WTRU is within the network coverage and / or outside the network coverage.

[0213] The WTRU may determine to include the WTRU's serving cell and / or gNB in ​​the discovery message. For example, a remote and / or relay WTRU may indicate its cell and / or gNB in ​​the discovery message. Such indication of the cell and / or gNB may help the WTRU to prioritize relay WTRUs that support multipath in the same cell and / or gNB.

[0214] Relay selection may be performed. For example, the WTRU may trigger relay (re)selection. In some examples, the WTRU may trigger relay (re)selection to select a relay (e.g., by itself). The WTRU may (e.g., then) report the selected relay to the network. In another example, the WTRU (e.g., a remote WTRU) may trigger reporting of a detected set of relays to the network. In some examples, the WTRU (e.g., a relay WTRU) may trigger reporting of a detected set of remote WTRUs (e.g., a set of remote WTRUs that sent discovery-relay-service messages with SD-RSRP greater than or equal to a threshold). The WTRU may trigger one or more of relay selection, relay WTRU set reporting, and / or remote WTRU set reporting (e.g., reporting to the network), for example, based on one or more of the following: Uu RSRP is within a (pre)configured range; relay load; an indication from another node (e.g., a gNB); and / or data from a set of SLRBs / LCHs in a buffer arrives or the amount of data from a set of SLRBs / LCHs is greater than or equal to a threshold.

[0215] The WTRU may trigger one or more of relay selection, relay WTRU set reporting, and / or remote WTRU set reporting (e.g., reporting to the network), for example, based on the Uu RSRP being within a (pre-)configured range. For example, the remote WTRU may trigger reporting of a detected set of relay WTRUs based on the Uu RSRP. In one example, if the Uu RSRP is within a (pre-)configured range, the WTRU may (e.g., then) report the detected set of relay WTRUs to the network. In another example, if the Uu RSRP is within a threshold range, the remote WTRU may trigger relay selection.

[0216] The WTRU may trigger one or more of relay selection, relay WTRU set reporting, and / or remote WTRU set reporting (e.g., reporting to the network), for example, based on the relay load. In one example, if the relay load is less than a threshold, the relay WTRU may trigger reporting of the detected set of remote WTRUs to the network. In another example, if the relay load is greater than a threshold, the relay WTRU may trigger reporting of the detected set of remote WTRUs to the network.

[0217] The WTRU may trigger one or more of relay selection, relay WTRU set reporting, and / or remote WTRU set reporting (e.g., reporting to the network), for example, based on an indication from another node (e.g., a gNB). In one example, the remote WTRU may trigger reporting of a detected set of relay WTRUs to the network based on a request from the network. The network may request the remote WTRU to report the detected set of WTRUs (e.g., using a dedicated RRC message). The WTRU may (e.g., then) perform reporting of the detected set of relay WTRUs.

[0218] The WTRU may trigger one or more of relay selection, relay WTRU set reporting, and / or remote WTRU set reporting (e.g., reporting to the network) based on the arrival of data from the set of SLRB / LCHs in the buffer and / or the amount of data from the set of SLRB / LCHs being greater than or equal to a threshold. For example, if the WTRU has data from the set of SLRB / LCHs in the buffer and / or the amount of data from the set of SLRB / LCHs is greater than or equal to a threshold, the WTRU (e.g., the remote WTRU) may trigger relay selection and / or trigger reporting of the detected set of relay WTRUs to the network. In another example, if the state of the buffered data changes (e.g., if the amount of data associated with the set of existing SLRB / LCH sets increases), the WTRU (e.g., the remote WTRU) may trigger (re)selection. The change in the state of the buffered data may indicate, for example, an insufficient rate of consumption of the buffered data due to the currently selected relay. The (re)selection may be triggered by a second threshold. The initial arrival of data from the set of SLRB / LCHs may cause the triggering and selection of the relay. Additionally or alternatively, an increase in data exceeding the second threshold may trigger a (re)selection event. A (re)selection event may cause a change in the relay WTRU selected by the remote WTRU.

[0219] A WTRU may determine its load. A WTRU (e.g., a relay WTRU) may determine its load based on one or more of the conditions herein (e.g., below). For example, a WTRU (e.g., a relay WTRU) may determine its load based on the channel occupancy (CR) of the WTRU. In another example, a WTRU (e.g., a relay WTRU) may determine its load based on the number of connected links. A WTRU (e.g., a relay WTRU) may determine its load based on the buffer status of the WTRU. In another example, a WTRU (e.g., a relay WTRU) may determine its load based on the number of connected remote WTRUs.

[0220] The WTRU may determine which relay to (re)select and / or which detected relay to report to the network, for example based on one or more of the following: the Uu RSRP of the relay WTRU; the relay type; the supported SLRB / LCH; the relay WTRU supporting dual connectivity; the relay WTRU supporting multipath in the same cell; and / or the measured Uu RSRP of the relay WTRU in the cell / gNB is greater than or equal to a threshold.

[0221] The WTRU may determine which relay to (re)select and / or which detected relay to report to the network based on the Uu RSRP of the relay WTRU. For example, the WTRU may select a relay and / or report to the network a detected relay whose Uu RSRP and / or SD-RSRP is greater than or equal to a threshold. The threshold may be a function of the WTRU's established SLRB / LCH.

[0222] The WTRU may determine which relay to (re)select and / or which detected relay to report to the network based on the relay type. For example, the WTRU may select and / or report a relay WTRU that supports multipath relay service.

[0223] The WTRU may determine which relay to (re)select and / or which detected relay to report based on the supported SLRB / LCH. For example, the WTRU may select and / or report a relay WTRU that supports the SLRB / LCH established by the WTRU.

[0224] The WTRU may determine which relay to (re)select and / or which detected relay to report to the network based on the relay WTRU supporting dual connectivity. For example, the WTRU may preferentially select a relay WTRU supporting dual connectivity.

[0225] The WTRU may determine which relay to (re)select and / or which detected relay to report to the network based on relay WTRUs supporting multipath in (e.g., the same) cell and / or gNB. For example, a WTRU (e.g., a remote WTRU) may prefer a relay WTRU connected to the same cell and / or gNB as its serving cell and / or gNB.

[0226] The WTRU may determine which relay to (re)select and / or which detected relay to report to the network based on the measured Uu RSRP of the relay WTRU in the cell and / or gNB being greater than or equal to a threshold. For example, the WTRU may receive a discovery message from a relay WTRU. The discovery message may indicate the serving cell and / or gNB. The WTRU may perform measurements (e.g., Uu RSRP) of the serving cell and / or gNB of the relay. For example, if the measured Uu RSRP is greater than or equal to a threshold, the WTRU may (e.g., then) prioritize the relay. In some examples, the WTRU may prioritize a relay whose SD-RSRP is greater than or equal to a threshold and has the highest Uu RSRP. In another example, the WTRU may prioritize a relay WTRU with the highest SD-RSRP and whose Uu RSRP of the serving cell and / or gNB is greater than or equal to a threshold. The SD-RSRP and / or Uu RSRP thresholds may be (pre)configured.

[0227] The WTRU may determine which relay to (re)select and / or which detected relay to report to the network based on the distance to the gNB. For example, if the WTRU is (pre)configured to select a single-hop relay service, the WTRU may select and / or report a relay WTRU whose distance to the gNB is within a range. The range may be (pre)configured. Alternatively or additionally, if the WTRU is (pre)configured to select a multipath relay service, the WTRU may select and / or report a relay WTRU whose distance to the gNB is greater than or equal to a threshold (e.g., a (pre)configured threshold). If two relays meet the (pre)configured distance to the gNB condition, the WTRU may give priority to one or more relay WTRUs with a smaller (e.g., shorter) distance to the network.

[0228] Figure 5 An example system 500 is illustrated that illustrates a remote WTRU 504 giving priority to a relay WTRU 502 associated with a gNB 510 whose measured UuRSRP is greater than or equal to a threshold. Figure 5As shown, if the remote WTRU 504 is leaving the coverage of gNB1 508, the remote WTRU 504 may detect Relay1 502 and / or Relay2 506. The SD-RSRP of Relay2 506 may be greater than the SD-RSRP of Relay1 502. In the discovery message, Relay1 502 may indicate the ID of gNB2 510 and / or Relay2 506 may indicate the ID of gNB3 512. The remote WTRU 504 may perform Uu RSRP measurement of gNB2 510 and / or gNB3 512. Additionally or alternatively, the remote WTRU 504 may determine that the Uu RSRP of gNB3 512 is less than a threshold. The WTRU may (e.g., then) preferentially select Relay1 502 for a multipath connection, such as Relay1 502 and gNB2 510.

[0229] The WTRU may determine whether to perform relay reselection. In an example, the WTRU may have multiple path links to the gNB. (E.g., one) link may be a Uu link and / or another link may be a relay link. The relay link may satisfy the conditions for relay reselection (e.g., one or more of the following: the WTRU detects RLF with the current relay, the SL-RSRP is less than a threshold, and / or the WTRU receives a release message from the relay WTRU). The WTRU may determine whether to perform relay reselection based on the RRC state of the WTRU and / or the Uu RSRP.

[0230] The WTRU may determine whether to perform relay reselection based on the RRC state of the WTRU. For example, if the WTRU is in an RRC connected state and / or if the WTRU is in an RRC inactive state, the WTRU may perform relay reselection and / or report the detected relay set to the network. For example, if the WTRU is in an RRC idle state, the WTRU may not perform relay reselection and / or report the detected relay set to the network.

[0231] The WTRU may determine whether to perform relay reselection based on the Uu RSRP. For example, if the Uu RSRP is less than a threshold, the WTRU may trigger relay reselection. The WTRU may be connected to a multipath relay. For example, if the Uu RSRP is less than a threshold, the WTRU may trigger a switch to a single-path relay. In another example, if the Uu RSRP is greater than or equal to a threshold, the WTRU may trigger relay reselection. For example, the WTRU may be connected to a single-path relay. For example, if the Uu RSRP is greater than or equal to a threshold, the WTRU may trigger a switch to a multipath relay.

[0232] The WTRU may determine whether to perform relay reselection and / or report the detected set of relays to the network. The WTRU may be connected to the gNB via Uu and / or a relay WTRU. The WTRU may detect that the current relay is no longer the preferred relay (e.g., the RSRP of the current relay is less than a threshold). The WTRU may determine whether to perform relay reselection and / or notify the network of the status of the current relay based on the Uu RSRP. If the Uu RSRP is greater than or equal to the threshold, the WTRU may report the event to the network. For example, if the WTRU has a good Uu connection with the network, the WTRU may report the event to the network. In another example (e.g., otherwise), if the Uu RSRP is less than a threshold, the WTRU may perform autonomous relay reselection. The WTRU may reselect a WTRU that supports single-path relaying.

[0233] Cell reselection of a multipath relay may be performed. For example, the WTRU may trigger cell reselection. The WTRU may trigger cell reselection and / or report a detected set of cells to the network, for example to support the network in a handover procedure. The WTRU may trigger cell reselection and / or report a detected set of cells to the network based on one or more of the following: the WTRU detects a relay with an SD-RSRP greater than or equal to a threshold; the WTRU detects a relay with an SD-RSRP offset greater than the SD-RSRP / SL-RSRP of the current relay; and / or the SL-RSRP / SD-RSRP of the current relay and / or the Uu RSRP of the current cell is less than a threshold.

[0234] The WTRU may trigger cell reselection and / or report a detected set of cells to the network based on the WTRU detecting a relay with an SD-RSRP greater than or equal to a threshold. For example, the WTRU may detect a relay with an SD-RSRP greater than or equal to a threshold. If the relay WTRU is in another cell and / or gNB, the WTRU may measure the Uu RSRP of the serving cell of the detected relay. The WTRU may (e.g., then) report the detected cell / gNB to the network. For example, if the Uu RSRP of the current gNB is less than a threshold and / or the WTRU detects a Uu RLF with the current gNB, the WTRU may reselect a cell associated with the relay.

[0235] The WTRU may trigger cell reselection and / or report a detected set of cells to the network based on the WTRU detecting a relay with an SD-RSRP offset greater than or equal to the SD-RSRP and / or SL-RSRP of the current relay. For example, the WTRU may detect a relay with an SD-RSRP offset greater than or equal to a threshold. For example, if the relay WTRU is in another cell and / or gNB, the WTRU may measure the Uu RSRP of the serving cell of the detected relay. The WTRU may (e.g., then) report the detection of the cell and / or gNB to the network. For example, if the Uu RSRP of the current gNB is less than a threshold and / or the WTRU detects a Uu RLF with the current gNB, the WTRU may reselect a cell associated with the relay.

[0236] The WTRU may trigger cell reselection and / or report the detected cell set to the network based on the SL-RSRP / SD-RSRP of the current relay and / or the Uu RSRP of the current cell being less than a threshold. If the SD-RSRP and / or SL-RSRP of the current relay is less than a threshold, the WTRU may trigger relay reselection and / or cell selection, for example to select a different relay and / or cell.

[0237] The WTRU may determine which cell to prioritize and / or report. In an example, the WTRU may trigger cell reselection and / or report a set of detected cells to the network to support the network in a handover procedure. The WTRU may determine which cell to reselect and / or report to the network based on one or more of the following: a cell WTRU and / or a cell / gNB that supports multipath (SD-RSRP measured by a relay in the cell is greater than or equal to a threshold).

[0238] The WTRU may determine which cell to reselect and / or report to the network based on the cell WTRU supporting multipath. For example, the WTRU (e.g., a remote WTRU) may prioritize cells that support multipath. Additionally or alternatively, the WTRU may perform Uu RSRP and / or SD-RSRP measurements (e.g., both). The WTRU may (e.g., then) prioritize cells in which both the Uu RSRP and SD-RSRP of the relay are greater than or equal to respective thresholds.

[0239] The WTRU may determine which cell to reselect and / or report to the network based on the cell and / or gNB (the SD-RSRP measured by the relay in the cell is greater than or equal to a threshold). For example, the WTRU may receive a discovery message from a relay WTRU. The discovery message may indicate a serving cell and / or gNB. The WTRU may perform measurements (e.g., UuRSRP) of the serving cell and / or gNB of the relay. For example, if the measured SD-RSRP is greater than or equal to a threshold, the WTRU may (e.g., then) prioritize the cell. In some examples, the WTRU may prioritize cells where the Uu RSRP is greater than or equal to a threshold and the relay in the cell has the highest SD-RSRP. For example, when the SD-RSRP of the relay is greater than or equal to a threshold, the WTRU may prioritize the cell WTRU with the highest Uu RSRP. The SD-RSRP and / or Uu RSRP thresholds may be (pre)configured.

[0240] The relay WTRU may perform one or more discovery transmissions. For example, a WTRU (e.g., a relay WTRU) may determine which type of discovery-relay-service message to send, a resource pool for sending the discovery message, and / or one or more of the parameters of the discovery-relay-service transmission. Additionally or alternatively, the WTRU may determine which type of discovery-relay-service message to send, a resource pool for sending the discovery message, and / or one or more of the parameters of the discovery-relay-service transmission based on one or more of the measured Uu RSRP of the WTRU, relay load, and / or relay capability.

[0241] The WTRU may receive configuration and / or conditions for one or more (e.g., each) type of discovery-relay-service messages (e.g., multipath vs. single path), for example, via the SIB or dedicated RRC. The conditions may include one or more of: Uu RSRP ranges (e.g., minimum Uu RSRP and maximum Uu RSRP) for single-path discovery; (e.g., different) min_Uu RSRP for multipath discovery-relay-service; relay capabilities (e.g., which may include support for single-path and / or multipath relaying); and / or QoS (e.g., priority) and send resource pool for one or more (e.g., each) type of discovery messages.

[0242] The WTRU may then determine which type of discovery-relay-service message to send based on one or more of the measured Uu RSRP, relay load, and / or the ability to support multipath and / or single path relaying. The WTRU may select a resource pool for sending the discovery message based on the discovery type. The WTRU may determine the sending parameters of the discovery message, for example, using the (pre-)configured QoS of the discovery message.

[0243] The WTRU may (e.g., then) indicate the following (e.g., information) in the discovery message: discovery-relay-service type (e.g., single path and / or multipath); Uu RSRP (e.g., for the remote WTRU to perform relay selection); and / or QoS (e.g., priority) of the discovery message. The WTRU may (e.g., then) perform the discovery transmission.

[0244] The remote WTRU may perform one or more discovery-relay-service transmissions. A WTRU (e.g., the remote WTRU) may determine whether to send a discovery message and / or the type of discovery-relay-service message (e.g., single path or multipath discovery), for example, based on one or more of the following: the WTRU's measured Uu RSRP, the received multipath SLRB configuration, and / or the arrival data from the SLRB / LCH set in the buffer. The WTRU may perform relay selection and / or report a set of relay WTRUs to the network, for example, based on the supported relay services of the detected relays and the remote WTRU's Uu RSRP and / or the remote WTRU's Uu RSRP.

[0245] The WTRU may receive (e.g., via RRC and / or SIB) conditions for sending one or more discovery-relay-service messages. The discovery-relay-message may include one or more of the following: maximum Uu RSRP for single-path discovery; Uu RSRP range for multi-path discovery (e.g., minimum Uu RSRP and / or (different) maximum Uu RSRP); SLRB / LCH set for triggering multi-path discovery; and / or minimum Uu RSRP for relay per SLRB / LCH.

[0246] The WTRU may trigger a discovery transmission. For example, the WTRU may trigger a discovery transmission based on one or more of: satisfying a Uu threshold for sending multipath discovery; upon receiving a SLRB / LCH configuration (e.g., which satisfies a configuration condition for multipath relaying); and / or upon receiving SLRB / LCH data (e.g., which satisfies a configuration condition for multipath relaying). The WTRU may (e.g., then) perform relaying one or more times in response to reception. The WTRU may (e.g., then) perform relay selection and / or select a relay set to notify the network. For example, the WTRU may (e.g., then) perform relay selection and / or select a relay set to notify the network, the relay set satisfying one or more of the following (e.g., conditions): supporting multipath; supporting an established SLRB / LCH; and / or the Uu RSRP of the relay is greater than or equal to a threshold (e.g., the threshold may be based on the SLRB / LCH of the remote WTRU).

[0247] The relay WTRU may determine which set of detected remote WTRUs to report to the network. Additionally or alternatively, the WTRU may determine which set of detected remote WTRUs to report to the network. The relay WTRU may indicate (e.g., send) information in a discovery message. The remote WTRU may indicate (e.g., send) its Uu connection status in a discovery-service message. The WTRU may determine to send the discovery-relay-service message. The WTRU may determine whether a cell supports one or more relay services. The WTRU may determine whether to send a discovery-relay-service message based on an indication from a cell. The WTRU may determine whether to respond to the remote WTRU (e.g., send to the remote WTRU). The WTRU may determine its load.

[0248] A WTRU (e.g., a first WTRU) may monitor one or more discovery messages. The one or more discovery messages may come from one or more second WTRUs. The WTRU may determine a set of the one or more second WTRUs, for example, based on the discovery message. The WTRU may report the set of the one or more second WTRUs, for example, to a network. The set of the one or more second WTRUs may be based on a support type. The support type may include one or more services in a single path service and a multipath service. The WTRU may compare a second WTRU reference signal received power (RSRP) with a threshold. The WTRU may determine the support type based on a comparison of the second WTRU RSRP with the threshold. For example, if the second WTRU RSRP is less than the threshold, the WTRU may determine that the support type is a single path service. In another example, if the second WTRU RSRP is less than the threshold, the WTRU may determine that the support type is a single path service. The WTRU may determine the support type based on the connection state of the second WTRU. The WTRU may compare the second WTRU quality of service (QoS) with a threshold.

[0249] A WTRU (e.g., a relay WTRU) may receive configuration information. The configuration information may indicate one or more parameters. The one or more parameters may be used to operate as a WTRU to network mobile relay. Additionally or alternatively, the parameters may include a first reference signal power (RSRP) threshold and / or a second RSRP threshold.

[0250] The WTRU may perform RSRP measurements. The WTRU may perform RSRP measurements of a serving cell, for example to determine an RSRP value. The WTRU may determine whether to indicate support for one or more of single-path operation and multi-path operation. The WTRU may determine, for example, based on the RSRP value, whether to indicate support for one or more of single-path operation and multi-path operation in a side link discovery message. The WTRU may indicate support for multi-path relay operation based on the RSRP value satisfying the second RSRP threshold. Additionally or alternatively, the WTRU may indicate support for single-path relay operation based on the RSRP value satisfying the first RSRP threshold. The WTRU may send, for example, the side link discovery message indicating support for one or more of single-path relay operation and multi-path relay operation. For example, the WTRU may send, based on the RSRP value, the side link discovery message indicating support for one or more of single-path relay operation and multi-path relay operation.

[0251] The parameter may include a relay load range. The WTRU may indicate support for the multipath relay operation based on the current relay load of the WTRU (e.g., less than the relay load range). The parameter may include an indication of a first resource pool and / or an indication of a second resource pool. The first resource pool may be used to send, for example, a first side link discovery message indicating support for the single path relay operation. The second resource pool may be used to send, for example, a second side link discovery message indicating support for the multipath relay operation. The side link discovery message may indicate the RSRP value. When the RSRP value is greater than or equal to the first RSRP threshold, the WTRU may indicate support for the single path relay operation. Additionally or alternatively, when the RSRP value is less than the second RSRP threshold, the WTRU may indicate support for the single path relay operation.

[0252] When the RSRP value is greater than or equal to the second RSRP threshold, the WTRU may indicate support for the multipath relay operation. The WTRU may, for example, send a report to the network based on the RSRP value. The report may indicate one or more second WTRUs. For example, when the RSRP value meets the first RSRP threshold, the report may indicate one or more second WTRUs requesting the single path relay operation. Additionally or alternatively, when the RSRP value meets (e.g., is greater than or equal to) the second RSRP threshold, the report may indicate one or more second WTRUs requesting multipath relay operation.

[0253] Figure 6 An example system 600 is illustrated that illustrates a relay WTRU 602, 606 determining whether to send single path discovery versus multi-path discovery based on a measured Uu RSRP being greater than or equal to a threshold. Figure 6As shown, the relay WTRU 602 and / or the relay WTRU 606 may receive a configuration (e.g., in the SIB and / or RRC) indicating whether to send single-path and (e.g., and / or) multi-path discovery service messages, for example, based on Uu RSRP. Additionally or alternatively, the configuration may include a relay load for sending multi-path discovery and / or a resource pool for multi-path discovery and / or single-path discovery. For example, additionally or alternatively, the indication of whether to send a single-path and (e.g., and / or) multi-path discovery service message may be based on the relay load for sending multi-path discovery and / or a resource pool for multi-path discovery and / or single-path discovery. The relay WTRU 602 and / or the relay WTRU 606 may receive the configuration from the gNB 610. For example, if the Uu RSRP is greater than Uu RSRP threshold 1 (e.g., a first threshold), the relay WTRU 602 may send a multipath discovery message, and / or if the Uu RSRP is between Uu RSRP threshold 1 (e.g., a first threshold) and Uu RSRP threshold 2 (e.g., a second threshold), the relay WTRU 606 may determine to send (e.g., may send) a single path discovery. The Uu RSRP threshold 2 (e.g., a second threshold) may be used to indicate a coverage boundary. The relay WTRU 602 and / or the relay WTRU 606 may measure the Uu RSRP and / or check the Uu RSRP conditions for multipath discovery and / or single path discovery. The relay WTRU 602 and / or the relay WTRU 606 may check the relay load conditions for multipath discovery and / or single path discovery. The relay WTRU 602 and / or the relay WTRU 606 may, for example, send a single path discovery message and / or a multipath discovery message in a (pre)configured resource pool (e.g., if a condition is met). For example, the relay WTRU 602 and / or the relay WTRU 606 may indicate the discovery type (e.g., single path and / or multipath) in the discovery message. The remote WTRU 604 may send one or more request messages for multipath. For example, the remote WTRU 604 may send one or more request messages for multipath if the Uu RSRP is greater than the Uu RSRP threshold 2 (e.g., the second threshold), and / or the remote WTRU 608 may send one or more single path request messages if its Uu RSRP is less than the Uu RSRP threshold 2 (e.g., the second threshold) and greater than the Uu RSRP threshold 3 (e.g., the third threshold, not shown). The remote WTRU 608 and the remote WTRU 604 may be the same WTRU, for example, moved farther away or closer to the gNB 610. Relay WTRU 602 and relay WTRU 606 may be the same WTRU, for example moved farther away or closer to the gNB 610.

[0254] The methods and means described herein may be applied in any combination. Additionally or alternatively, the processes and means described herein may be applied to other wireless technologies and / or for other services.

[0255] A WTRU may refer to an identity of a physical device and / or to an identity of a user, such as an identity associated with a subscription (e.g., MSISDN, SIP URI, etc.). Additionally or alternatively, a WTRU may refer to an application-based identity (e.g., a user name that each application may use).

[0256] The processes described above may be implemented in a computer program, software, and / or firmware incorporated in a computer-readable medium, for example, for execution by a computer and / or a processor. Examples of computer-readable media may include, but are not limited to, electronic signals (e.g., sent via a wired or wireless connection) and / or computer-readable storage media. Examples of computer-readable storage media may include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media (e.g., but not limited to built-in hard disks and removable disks), magneto-optical media, and / or optical media (e.g., CD-ROM disks and / or digital versatile disks (DVDs)). For example, a processor associated with software may be used to implement a radio frequency transceiver for use in one or more of a WTRU, UE, terminal, base station, RNC, and / or any host computer.

Claims

1. A wireless transmit / receive unit (WTRU), wherein: include: A processor and a memory, wherein the processor and the memory are configured to: receiving configuration information indicating parameters for operating as a WTRU-to-network mobile relay, the parameters comprising a first reference signal received power (RSRP) threshold and a second RSRP threshold; Performing RSRP measurement of the serving cell to determine the RSRP value; determining whether to indicate support for one or more of single path operation or multipath operation in a sidelink discovery message based on the RSRP value, wherein support for multipath relay operation is indicated based on the RSRP value satisfying the second RSRP threshold, and support for single path relay operation is indicated based on the RSRP value satisfying the first RSRP threshold; as well as The sidelink discovery message indicating support for single-path relay operation or multi-path relay operation is sent based on the RSRP value.

2. The WTRU of claim 1 , wherein the parameters further comprise a relay load range, and the processor and the memory are configured to: The sidelink discovery message is used to indicate support for the multipath relay operation based on a current relay load of the WTRU being less than a relay load range.

3. The WTRU according to claim 1, wherein the parameters further include an indication of a first resource pool and a second resource pool, wherein the first resource pool is used to send a first side link discovery message indicating support for the single-path relay operation, and the second resource pool is used to send a second side link discovery message indicating support for the multi-path relay operation.

4. The WTRU of claim 1 , wherein the sidelink discovery message indicates the RSRP value.

5. The WTRU of claim 1 , wherein the processor and the memory are configured to: When the RSRP value is greater than or equal to the first RSRP threshold, the sidelink discovery message is used to indicate support for the single-path relay operation.

6. The WTRU of claim 5, wherein the processor and the memory are configured to: When the RSRP value is less than the second RSRP threshold, the sidelink discovery message is used to indicate support for the single-path relay operation.

7. The WTRU of claim 1 , wherein the processor and the memory are configured to: When the RSRP value is greater than or equal to the second RSRP threshold, the sidelink discovery message is used to indicate support for the multipath relay operation.

8. The WTRU of claim 1 , wherein the processor and the memory are configured to indicate support for the single-path operation and the multi-path operation in the sidelink discovery message.

9. The WTRU of claim 1 , wherein the processor and the memory are configured to: and sending a report to a network, the report indicating one or more second WTRUs requesting the single path relay operation when the RSRP value satisfies the first RSRP threshold.

10. The WTRU of claim 1 , wherein the processor and the memory are configured to: and sending a report to a network, the report indicating one or more second WTRUs requesting the multipath relay operation when the RSRP value satisfies the second RSRP threshold.

11. A method implemented by a wireless transmit / receive unit (WTRU), the method include: receiving configuration information indicating parameters for operating as a WTRU-to-network mobile relay, the parameters comprising a first reference signal received power (RSRP) threshold and a second RSRP threshold; Performing RSRP measurement of the serving cell to determine the RSRP value; determining whether to indicate support for one or more of single path operation or multipath operation in a sidelink discovery message based on the RSRP value, wherein the WTRU is configured to indicate support for multipath relay operation based on the RSRP value satisfying the second RSRP threshold, and to indicate support for single path relay operation based on the RSRP value satisfying the first RSRP threshold; as well as The sidelink discovery message indicating support for single-path relay operation or multi-path relay operation is sent based on the RSRP value.

12. The method of claim 11, wherein the parameters further include a relay load range, and wherein the method further include: The sidelink discovery message is used to indicate support for the multipath relay operation based on a current relay load of the WTRU being less than a relay load range.

13. The method according to claim 11, wherein the parameters further include an indication of a first resource pool and a second resource pool, wherein the first resource pool is used to send a first side link discovery message indicating support for the single-path relay operation, and the second resource pool is used to send a second side link discovery message indicating support for the multi-path relay operation. The method of claim 11 , wherein the sidelink discovery message indicates the RSRP value.

15. The method according to claim 11, further comprising: include: When the RSRP value is greater than or equal to the first RSRP threshold, the sidelink discovery message is used to indicate support for the single-path relay operation.

16. The method according to claim 15, further comprising: include: When the RSRP value is less than the second RSRP threshold, the sidelink discovery message is used to indicate support for the single-path relay operation.

17. The method according to claim 11, further comprising: include: When the RSRP value is greater than or equal to the second RSRP threshold, the sidelink discovery message is used to indicate support for the multipath relay operation.

18. The method according to claim 11, further comprising: include: Support for the single-path operation and the multi-path operation is indicated in the sidelink discovery message.

19. The method according to claim 11, further comprising: include: and transmitting a report to a network, the report indicating one or more second WTRUs requesting the single path relay operation when the RSRP value satisfies the first RSRP threshold.

20. The method according to claim 11, further comprising: include: and transmitting a report to a network, the report indicating one or more second WTRUs requesting the multipath relay operation when the RSRP value satisfies the second RSRP threshold.

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