NR relay – methods for relay discovery and selection for mesh network

Abstract

A first wireless transmit / receive unit (WTRU) may receive, from a second WTRU, a first discovery message. The first discovery message may indicate a preferred source property associated with a source property of a cell or a preferred destination property associated with a destination property of the cell. The first WTRU may determine whether the source property satisfies the preferred source property or the destination property satisfies the preferred destination property. The first WTRU may send, to the second WTRU, a second discovery message based on the source property satisfying the preferred source property or the destination property satisfying the preferred destination property.

Description

NR RELAY - METHODS FOR RELAY DISCOVERY AND SELECTION FOR MESH NETWORKCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. provisional patent application No. 63 / 701 ,292 filed on September 30, 2024, the entire contents of which are incorporated herein by reference.BACKGROUND

[0002] Release 17 and / or Release 18 of fifth generation (5G) new radio (NR) may support single-hop wireless user equipment (UE)-to UE (U2U) and / or UE-to-network (U2N) Relay. Both Model A and Model B discovery and / or relay (re-)selection may be supported. Model A, a UE, or a wireless transmit / receive unit (WTRU) (e.g., Relay WTRU) may transmit discovery announcement messages to offer a relay service to remote WTRUs. For Model B, a WTRU (e.g., remote WTRU) may transmit discovery solicitation message to request for a relay service.SUMMARY

[0003] A first wireless transmit / receive unit (WTRU) may receive, from a second WTRU, may receive a first discovery message. The first discovery message may indicate a preferred source property associated with a source property of a cell and / or a preferred destination property associated with a destination property of the cell. The first WTRU may determine whether the source property satisfies the preferred source property, and / or the destination property satisfies the preferred destination property. The first WTRU may send, to the second WTRU, a second discovery message based on the source property satisfying the preferred source property, and / or the destination property satisfying the preferred destination property.

[0004] The first discovery message may be a discovery solicitation message. The second discovery message may be a discovery response message. The source property and / or the destination property may comprise one or more of a public land mobile network (PLMN) identifier, a number of hops supported by the second WTRU, and / or a quality of service (QoS) supported by the second WTRU. The first discovery message may comprise one or more indications. The one or more indications may comprise an indication of the weighted path value of the path associated with the first discovery message, a PLMN identifier, an indication of a stored path, an indication of a measurement associated with the first discovery message, or an indication from a node. The node may be a remote WTRU, a relay WTRU, or a network entity.

[0005] The second discovery message may comprise at least one of the one or more indications that comprise the first discovery message and / or an indication that the sourceproperty does satisfy the preferred source property or the destination property does satisfy the preferred destination property. The second discovery message may comprise an indication of the current path of the first WTRU.

[0006] The first WTRU may send, to the second WTRU, a message indicating that the first WTRU has accepted the first discovery message. The first WTRU may receive, from the second WTRU, an indication to send the second discovery message to the second WTRU.

[0007] A first wireless transmit / receive unit (WTRU) may receive, from a second WTRU, may receive a first discovery message. The first discovery message may indicate a preferred source property associated with a source property of a cell and / or a preferred destination property associated with a destination property of the cell. The first WTRU may determine whether the source property satisfies the preferred source property, and / or the destination property satisfies the preferred destination property. The first WTRU may send, to a node, a second discovery message based on the source property not satisfying the preferred source property, and / or the destination property not satisfying the preferred destination property.

[0008] The first discovery message may be a discovery solicitation message. The second discovery message may be a discovery response message. The source property and / or the destination property may comprises one or more of a PLMN identifier, a number of hops supported by the second WTRU, and / or a QoS supported by the second WTRU. The node is a remote WTRU, a relay WTRU, and / or a network entity.

[0009] The first discovery message comprises one or more indications. The one or more indications may comprise an indication of the weighted path value of the path associated with the first discovery message, a PLMN identifier, an indication of a stored path, an indication of a measurement associated with the first discovery message, and / or an indication from another node.

[0010] The second discovery message comprises at least one of the one or more indications that comprise the first discovery message and / or an indication that the source property does not satisfy the preferred source property and / or the destination property does not satisfy the preferred destination property. The second discovery message may comprise an indication of the current path of the first WTRU.

[0011] The first WTRU may send, to the second WTRU, a message indicating that the first WTRU has accepted the first discovery message. The first WTRU may receive, from the node, an indication to send the second discovery message to the second WTRU.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1A is a system diagram illustrating an example communications system in which one or more disclosed embodiments may be implemented.

[0013] FIG. 1 B is a system diagram illustrating an example wireless transmit / receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1A according to an embodiment.

[0014] FIG. 1C is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communications system illustrated in FIG. 1A according to an embodiment.

[0015] FIG. 1 D is a system diagram illustrating a further example RAN and a further example CN that may be used within the communications system illustrated in FIG. 1A according to an embodiment.

[0016] FIG. 2 depicts a wireless transmit / receive unit (WTRU) that determines whether to forward a discovery message for a remote WTRU based on a public land mobile network (PLMN).

[0017] FIG. 3 depicts a WTRU that determines whether to forward a discovery announcement message from another relay.

[0018] FIG. 4 depicts degradation and / or radio link failure (RLF) in one hop.

[0019] FIG. 5 depicts example scenarios for path switching.DETAILED DESCRIPTION

[0020] FIG. 1A is a diagram illustrating an example communications system 100 in which one or more disclosed embodiments may be implemented. The communications system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 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 multicarrier (FBMC), and the like.

[0021] As shown in FIG. 1A, the communications system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a RAN 104 / 113, a CN 106 / 115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112,though it will be appreciated 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 a “STA”, may be configured to transmit and / or receive wireless signals and may include a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like. Any of the WTRUs 102a, 102b, 102c and 102d may be interchangeably referred to as a WTRU.

[0022] The communications systems 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106 / 115, the Internet 110, and / or the 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, a NR NodeB, 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 will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0023] The base station 114a may be part of the RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and / or the base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for a wireless service to a specific geographical area that may be relatively fixed or that may change over time. The cell may further be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e. , one foreach 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 transmit and / or receive signals in desired spatial directions.

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

[0025] More specifically, as noted above, the communications 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, and the like. 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 establish the air interface 115 / 116 / 117 using wideband CDMA (WCDMA). 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).

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

[0027] 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).

[0028] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together, for instance using dual connectivity (DC) principles. Thus, the air interface utilized by WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., a eNB and a gNB).

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

[0030] The base station 114b in FIG. 1 A may be a wireless router, Home Node B, Home eNode B, or access point, for example, and may utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a place of business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a roadway, 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 cellularbased RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell. As shown in FIG. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the CN 106 / 115.

[0031] 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 varying quality of service (QoS) requirements, such as differing throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106 / 115 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not shown in FIG. 1A, 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 be utilizing a NR radio technology, the CN 106 / 115 may also be in communication with another RAN (not shown) employing a GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0032] 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 the other networks 112. The PSTN 108 may include circuit-switched telephone networks that provide plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devicesthat use common communication protocols, such as the transmission control protocol (TCP), user datagram protocol (UDP) and / or the internet protocol (IP) in the TCP / IP internet protocol suite. The networks 112 may include wired and / or wireless communications 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.

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

[0034] FIG. 1 B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1 B, the WTRU 102 may include 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, among others. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0035] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), a state machine, and the like. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. While FIG. 1 B depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0036] The transmit / receive element 122 may be configured to transmit signals to, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmit / receive element 122 maybe an emitter / detector configured to transmit and / or receive IR, UV, or visible light signals, for example. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF and light signals. It will be appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0037] Although the transmit / receive element 122 is depicted in FIG. 1 B 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.

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

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

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

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

[0042] The processor 118 may further be coupled to other peripherals 138, which may include one or more software and / or hardware modules that provide additional features, functionality and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photographs and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a Virtual Reality and / or Augmented Reality (VR / AR) device, an activity tracker, and the like. The peripherals 138 may include one or more sensors, the sensors may be one or more of 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.

[0043] The WTRU 102 may include a full duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for both the 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 to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, the WRTU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for either the UL (e.g., for transmission) or the downlink (e.g., for reception)).

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

[0045] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with anembodiment. The eNode-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 eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the eNode-B 160a, for example, may use multiple antennas to transmit wireless signals to, and / or receive wireless signals from, the WTRU 102a.

[0046] Each of the eNode-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 the UL and / or DL, and the like. As shown in FIG. 1C, the eNode-Bs 160a, 160b, 160c may communicate with one another over an X2 interface.

[0047] The CN 106 shown in FIG. 1C 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 are depicted as part of the CN 106, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0048] The MME 162 may be connected to each of the eNode-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, and the like. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0049] The SGW 164 may be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 104 via the 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 user planes during inter-eNode B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing contexts of the WTRUs 102a, 102b, 102c, and the like.

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

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

[0052] Although the WTRU is described in FIGS. 1A-1D as a wireless terminal, it is contemplated that in certain representative embodiments that such a terminal may use (e.g., temporarily or permanently) wired communication interfaces with the communication network.

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

[0054] A WLAN in Infrastructure Basic Service Set (BSS) mode may have an Access Point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have an access or an interface to a Distribution System (DS) or another type of wired / wireless network that carries traffic in to and / or out of the BSS. Traffic to STAs that originates from outside the BSS may arrive through the AP and may be delivered to the STAs. Traffic originating from STAs to destinations outside the BSS may be sent to the AP to be delivered to respective destinations. Traffic between STAs within the BSS may be sent through the AP, for example, where the source STA may send traffic to the AP and the AP may deliver the traffic to the destination STA. The traffic between STAs within a BSS may be considered and / or referred to as peer-to-peer traffic. The peer-to-peer traffic may be sent between (e.g., directly between) the source and destination STAs with a direct link setup (DLS). In certain representative embodiments, the DLS may use an 802.11e DLS or an 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and the STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other. The IBSS mode of communication may sometimes be referred to herein as an “ad-hoc” mode of communication.

[0055] When using the 802.11ac infrastructure mode of operation or a similar mode of operations, the AP may transmit a beacon on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling. The primary channel may be the operating channel of the BSS and may be used by the STAs to establish a connection with the AP. In certain representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) may be implemented, for example in in 802.11 systems. For CSMA / CA, the STAs (e.g., every STA), including the AP, may sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0056] High Throughput (HT) STAs may use a 40 MHz wide channel for communication, for example, via a combination of the primary 20 MHz channel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHz wide channel.

[0057] Very High Throughput (VHT) STAs may support 20MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels. The 40 MHz, and / or 80 MHz, channels may be formed by combining contiguous 20 MHz channels. A 160 MHz channel may be formed by combining 8 contiguous 20 MHz channels, or by combining two non-contiguous 80 MHz channels, which may be referred to as an 80+80 configuration. For the 80+80 configuration, the data, after channel encoding, may be passed through a segment parser that may divide the data into two streams. Inverse Fast Fourier Transform (IFFT) processing, and time domain processing, may be done on each stream separately. The streams may be mapped on to the two 80 MHz channels, and the data may be transmitted by a transmitting STA. At the receiver of the receiving STA, the above described operation for the 80+80 configuration may be reversed, and the combined data may be sent to the Medium Access Control (MAC).

[0058] Sub 1 GHz modes of operation are supported by 802.11 af and 802.11 ah. The channel operating bandwidths, and carriers, are reduced in 802.11af and 802.11 ah relative to those used in 802.11 n, and 802.11ac. 802.11af supports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non- TVWS spectrum. According to a representative embodiment, 802.11ah may support Meter Type Control / Machine-Type Communications, such as MTC devices in a macro coverage area. MTC devices may have certain capabilities, for example, limited capabilities including support for (e.g., only support for) certain and / or limited bandwidths. The MTC devices may include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0059] WLAN systems, which may support multiple channels, and channel bandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11 ah, include a channel which may be designated as the primary channel. The primary channel may have a bandwidth equal to the largest 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, from among all STAs in operating in a BSS, which supports the smallest bandwidth operating mode. In the example of 802.11ah, the primary channel may be 1 MHz wide for STAs (e.g., MTC type devices) that support (e.g., only support) a 1 MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or Network Allocation Vector (NAV) settings may depend on the status of the primary channel. If the primary channelis busy, for example, due to a STA (which supports only a 1 MHz operating mode), transmitting to the AP, the entire available frequency bands may be considered busy even though a majority of the frequency bands remains idle and may be available.

[0060] In the United States, the available frequency bands, which may be used by 802.11 ah, are from 902 MHz to 928 MHz. In Korea, the available frequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the available frequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidth available for 802.11 ah is 6 MHz to 26 MHz depending on the country code.

[0061] FIG. 1 D is a system diagram illustrating the RAN 113 and the CN 115 according to an embodiment. As noted above, the RAN 113 may employ an 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.

[0062] 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, gNBs 180a, 108b may utilize beamforming to transmit signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a, for example, may use multiple antennas to transmit 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 unlicensed spectrum while the remaining component carriers may be on licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement Coordinated Multi-Point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0063] The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using transmissions associated with a scalable numerology. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using subframe or transmission time intervals (TTIs) of various or scalable lengths (e.g., containing varying number of OFDM symbols and / or lasting varying lengths of absolute time).

[0064] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In thestandalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c without also accessing other RANs (e.g., such as eNode-Bs 160a, 160b, 160c). In the standalone configuration, WTRUs 102a, 102b, 102c may utilize one or more of gNBs 180a, 180b, 180c as a mobility anchor point. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration WTRUs 102a, 102b, 102c may communicate with / connect to gNBs 180a, 180b, 180c while also communicating with / connecting to another RAN such as eNode-Bs 160a, 160b, 160c. For example, WTRUs 102a, 102b, 102c may implement DC principles to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In the non-standalone configuration, eNode-Bs 160a, 160b, 160c may serve as a mobility anchor for WTRUs 102a, 102b, 102c and gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for servicing WTRUs 102a, 102b, 102c.

[0065] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards User Plane Function (UPF) 184a, 184b, routing of control plane information towards Access and Mobility Management Function (AMF) 182a, 182b and the like. As shown in FIG. 1 D, the gNBs 180a, 180b, 180c may communicate with one another over an Xn interface.

[0066] The CN 115 shown in FIG. 1D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. While each of the foregoing elements are depicted as part of the CN 115, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0067] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and may serve as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, support for network slicing (e.g., handling of different PDU sessions with different requirements), selecting a particular SMF 183a, 183b, management of the registration area, termination of NAS signaling, mobility management, and the like. Network slicing may be used by the AMF 182a, 182b in order to customize CN support for WTRUs 102a, 102b, 102c based on the types of services being utilized WTRUs 102a, 102b, 102c. For example, different network slices may be established for different use cases such as services relying on ultra-reliable low latency(URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for machine type communication (MTC) access, and / or the like. 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.

[0068] The SMF 183a, 183b may be connected to an AMF 182a, 182b in the CN 115 via an N11 interface. The SMF 183a, 183b may also be connected to a U PF 184a, 184b in the CN 115 via an N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure the routing of traffic through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating WTRU IP address, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, and the like. A PDU session type may be IP-based, non-IP based, Ethernet-based, and the like.

[0069] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The 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, and the like.

[0070] 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 serves 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 the other networks 112, which may include other wired and / or wireless networks that are owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to a local Data Network (DN) 185a, 185b through the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0071] In view of Figures 1A-1 D, and the corresponding description of Figures 1A-1D, one or more, or all, of the functions described herein with regard to one or more of: WTRU 102a-d, Base Station 114a-b, eNode-B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-ab, UPF 184a-b, SMF 183a-b, DN 185a-b, and / or any other device(s) described herein, may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more, or all, of the functions describedherein. For example, the emulation devices may be used to test other devices and / or to simulate network and / or WTRU functions.

[0072] The emulation devices may be designed to implement one or more tests of other devices in a lab environment and / or in an operator network environment. For example, the one or more emulation devices may perform the one or more, 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. The one or more emulation devices may perform the one or more, or all, functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The emulation device may be directly coupled to another device for purposes of testing and / or may perform testing using over-the-air wireless communications.

[0073] The one or more emulation devices may perform the one or more, including all, functions while not being implemented / deployed as part of a wired and / or wireless communication network. For example, the emulation devices may be utilized in a testing scenario in a testing laboratory and / or a non-deployed (e.g., testing) wired and / or wireless communication network in order to implement testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and / or wireless communications via RF circuitry (e.g., which may include one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0074] A wireless / transmit receive unit (WTRU) may monitor discovery transmission from another node. The WTRU may trigger a discovery transmission. The WTRU may determine whether to forward a discovery message based on its connection status with a source and / or destination. The WTRU may determine whether to forward a discovery message. The WTRU may determine whether to forward a discovery message based on the property of its source and / or destination. The WTRU may obtain the property of its source and / or destination. The WTRU may determine the validity of a property associated with a source and / or destination. The WTRU may forward the set of detected remote WTRUs to the source and / or destination. The WTRU may determine whether to transmit discovery response message to a remote WTRU. The WTRU may determine whether to forward a discovery based on the detected property of a source and / or destination. The WTRU may determine whether to forward a discovery announcement message from a WTRU. The WTRU may determine the weighted- path value associated with a path. The WTRU may store a detected path to a source and / or destination. The WTRU may determine the validity of a detected path to a source and / or destination. The WTRU may release the current path associated with the source and / ordestination upon establishing the shorter path. The WTRU may request another WTRU to stop / start transmitting discovery message. The WTRU may release one or more remote WTRUs upon changing the path to the source

[0075] For Model B discovery and / or relay (re-)selection: in a user equipment (UE) (e.g., WTRU) to network (U2N) Relay, upon reception of a discovery solicitation message from a remote WTRU, the U2N Relay may transmit the response message to the remote WTRU indicating its public land mobile network (PLMN ID). The criteria specified to transmit the response message may be the measured reference signal received power (RSRP) of the discovery message. Specifically, the U2N Relay may respond to the remote WTRU if the measured SD-RSRP is greater than a configured threshold. After receiving discovery response from one or multiple U2N Relays, the remote WTRU may select one of the U2Ns. The criteria to select the U2N Relay may be, e.g., sidelink measurement and / or PLMN ID. Specifically, the remote WTRU may select the matched PLMN ID.

[0076] In a UE (e.g., WTRU) to UE (e.g., WTRU) (U2U) Relay, upon reception of discovery solicitation message from a remote WTRU, the U2U Relay may forward its solicitation message if reference signal received power (RSRP) of the solicitation message is greater than a configured threshold.

[0077] For model A discovery and / or relay (re-)selection: in U2N Relay, the WTRU may transmit discovery announcement message if Uu RSRP is within a configured range. In U2U Relay, the U2U Relay may indicate in its discovery announcement message all the neighbor remote WTRUs (e.g., the remote WTRU with RSRP being greater than a configured threshold).

[0078] Regarding relay (re-)selection, when there is radio link failure (RLF) (e.g., in the Uu link for the U2N Relay, in a remote-U2U relay link), the WTRU may indicate the RLF to the remote WTRU for the remote WTRU to trigger relay reselection. A WTRU may trigger discovery transmission and / or reception if sidelink measured reference signal received power (SL-RSRP) of the current link is smaller than a configured threshold.

[0079] Regarding discovery transmission, using the existing mechanism to determine whether to transmit a discovery message based on the channel measurement (e.g., SL-RSRP and / or Uu RSRP) may results in too many discovery transmissions. Many transmissions may not be necessary. The relay WTRU may already connect to the requested destination. The relay WTRU may need to establish limited number of paths (e.g., only one shortest path) to the source. Forwarding many discovery messages may require the WTRU to establish different paths to the same source with different characteristic such as number of hops and / or channel conditions.

[0080] For multi-hop relay, the WTRU may already have existing connection with the network. However, the WTRU may connect to multiple different cells with different cell properties. Relying on the current connected cell to response for a discovery solicitation service may limit the support of such relay WTRU as the remote WTRU may rely on such response to select a relay for its transmission to the network.

[0081] Regarding relay (re-)selection due to RLF, for multi-hop relay, RLF in one hop may require many WTRUs to reselect a different path. Channel degradation in one hop may require one or more WTRUs in the whole path to react to prepare for path reselection by triggering transmission and / or reception of discovery even though the channel condition in a certain hop is still acceptable (e.g., good). Because the parent relay may not reach the desired source (e.g., gNB) event, the channel condition to the parent relay is still acceptable (e.g., good).

[0082] Herein addressed is how to design a discovery and / or relay reselection procedure to minimize discovery transmission while still ensuring quality of service (QoS) associated with the relay service.

[0083] A WTRU (e.g., intermediate relay having established connection with the gNB having associated cell property), upon reception of a discovery solicitation message from another WTRU (e.g., a remote WTRU) may determine which discovery message to transmit (e.g., discovery solicitation forwarding message and / or discovery response message). The discovery may be based on whether the requested source and / or destination property (e.g., PLMN ID, number of hops supported, and / or QoS supported) indicated in the discovery message is satisfied by the current source and / or destination property of the WTRU (e.g., the current gNB).

[0084] The WTRU may establish a connection with a cell having associated cell property (e.g., PLMN ID) via one or more relays. The WTRU may receive a discovery solicitation message from other WTRU (e.g., remote WTRU), which has an associated preferred source and / or destination property (e.g., PLMN ID).

[0085] The WTRU may determine which discovery message to transmit based on whether the source and / or destination property (e.g., PLMN ID) of its current source and / or destination satisfies the preferred source and / or destination property (e.g., PLMN ID), indicated in the received discovery message. If the current source and / or destination property (e.g., PLMN IDs) does not satisfy the preferred source and / or destination property indicated in the discovery message, the WTRU may forward the discovery solicitation message. Otherwise, the WTRU may transmit the discovery response message and / or indicate its current path in the response message.

[0086] In other words, an initial (e.g., first) WTRU may receive, from another (e.g., second) WTRU, a discovery message may indicate a preferred source property associated with a source property of a cell and / or a preferred destination property associated with a destination property of the cell. The initial WTRU may determine whether the source property satisfies the preferred source property or the destination property satisfies the preferred destination property. The initial WTRU may send, to the second WTRU, a second discovery message based on the source property satisfying the preferred source property or the destination property satisfying the preferred destination property.

[0087] The WTRU may transmit the determined discovery message. This may enable the WTRU to selectively transmit discovery message. Selective transmission of the discovery message may minimize the signaling overhead of discovery transmission while still maintaining the QoS associated with discovery transmission.

[0088] As disclosed herein, explaining that the WTRU is (pre-)configured with something means the WTRU may be preconfigured with one or more parameters, thresholds, and / or or the WTRU may receive configuration from another node (e.g., a relay node and / or the gNB).

[0089] The term discovery message may describe any message that serves the purpose of discovering the WTRU (e.g., relay WTRU and / or remote WTRU) for potential path establishment. The discovery message may serve the purpose for discovery and / or connection request such as direct communication request.

[0090] The terms source node, destination node, parent node, child node, relay node, and / or remote node may be used interchangeably. These terms may describe the action of any node (e.g., WTRU node, network node such as gNB, cell, and / or TRP). The source and / or destination node may indicate one end of a path. The child node may be used to the next destination of a message. The parent node may indicate the previous destination of a message and / or the previous transmitter of a message. In this disclosure, the terms cell, TRP, and / or gNB may be used interchangeably.

[0091] The WTRU may monitor discovery transmission from another node. A WTRU may monitor discovery message from other WTRUs. The WTRU may monitor a discovery announcement message from one or more relay WTRUs. The announcement message may announce the support of a relay service. The WTRU may monitor discovery solicitation message from remote WTRUs and / or intermediate relay WTRUs. The solicitation message may request the relay service for the remote WTRUs.

[0092] The WTRU may trigger discovery transmission. A WTRU (e.g., an intermediate relay, a first relay) may receive a discovery message from another WTRU (e.g., remote WTRU). TheWTRU may receive a discovery solicitation message from a WTRU (e.g., a remote WTRU and / or an intermediate relay WTRU). The discovery solicitation message may be used for the remote WTRU to request for a relay service. The WTRU may receive a discovery announcement message from a relay WTRU (e.g., the U2N Relay and / or an intermediate Relay). The discovery announcement message may be used by a relay WTRU to offer a relay service. The WTRU may perform one or any combination of the following upon reception of a discovery message from another node:

[0093] The WTRU may forward the discovery message to a subsequent node. Specifically, for Model A discovery, the WTRU may forward the discovery announcement message from another relay WTRU (e.g., another intermediate Relay and / or U2N Relay). This discovery announcement message may transmit to a subsequent relay WTRU and / or a remote WTRU. For Model B discovery, the WTRU may forward the discovery solicitation message from another WTRU (e.g., a remote WTRU and / or an intermediate Relay). This discovery solicitation message may transmit to a subsequent relay WTRU (e.g., an intermediate relay and / or a U2N Relay).

[0094] The WTRU may indicate the set of detected remote WTRUs to the subsequent node (e.g., a parent node). Specifically, an intermediate relay may have an established connection (e.g., a PC5 RRC connection) with its parent node (e.g., an U2N relay and / or the last relay). The WTRU, upon reception of discovery solicitation message from a WTRU (e.g., a remote WTRU and / or an intermediate Relay WTRU), may then forward the set of detected remote WTRUs and / or the associated path to the parent node. The WTRU may use non-access stratum (NAS), PC5 radio resource control (RRC), medium access control element (MAC CE), and / or sidelink control information (SCI) to indicate such information.

[0095] The WTRU may transmit a discovery response to the other WTRU by transmitting a solicitation message (e.g., the remote WTRU and / or an intermediate relay WTRU), which may accept the relay request from the remote WTRU. Specifically, the WTRU may receive discovery solicitation message from a remote WTRU or from a relay WTRU forwarding the solicitation message for a remote WTRU. The WTRU may first forward the discovery solicitation message to a subsequent relay WTRU. Upon reception of the discovery response message from the subsequent relay WTRU, the WTRU may then transmit back a discovery response message to the remote WTRU. The WTRU may already have established a PC5 RRC connection with a parent relay WTRU (e.g., U2N Relay). The WTRU may send the set of detected remote WTRUs to the parent relay using a PC5 RRC and / or NAS message. Upon reception of the responsemessage to serve the remote WTRU, the WTRU may then send back the discovery response message to the remote WTRU.

[0096] The WTRU may directly send the discovery response message to the remote WTRU to accept the relay service request from the remote WTRU. The WTRU may directly respond to solicitation message from the remote WTRU if the WTRU has not received an indication from the parent relay to stop offering the relay service for additional remote WTRUs.

[0097] The WTRU may determine whether to forward discovery message based on its connection status with a source and / or destination. The WTRU may receive a discovery message (e.g., a discovery solicitation message and / or a discovery announcement message) from another WTRU. The WTRU may then determine whether to forward the discovery message based on its connection status associated with a source and / or destination (e.g., a gNB). Specifically, in one approach, the WTRU may forward the discovery message if it has established a connection with the source and / or destination (e.g., the gNB). Otherwise, if the WTRU has not established a connection with the source and / or destination, the WTRU may decide not to forward the discovery message. The WTRU may not forward the discovery message if the WTRU has established a connection with the source and / or destination. Otherwise, if the WTRU has established a connection with the source and / or destination, the WTRU may decide to forward the discovery message.

[0098] The WTRU (e.g., a relay WTRU) may have established a connection with its source and / or destination. The WTRU may receive discovery message from another WTRU (e.g., discovery solicitation message and / or discovery announcement message). The WTRU may then determine whether to forward the discovery message to a subsequent node based on one or any combination of the following:

[0099] The preferred property of the source and / or destination (e.g., the PLMN ID) may be associated with the discovery message. This preferred property may be indicated in the discovery message. Specifically, the remote WTRU and / or its associated relay may transmit discovery messages to indicate its preferred property of the source and / or destination; the weighted-path value of the path associated with the discovery message; the supported property of its source and / or destination (e.g., the PLMN ID); the stored detected path(s) to the source and / or destination of the discovery message; the measurement associated with the discovery message; and / or the indication from another node.

[0100] The WTRU may determine whether to forward a discovery message based on the property of its source and / or destination. The WTRU may have established a connection with its source and / or destination (e.g., a gNB). The WTRU may receive discovery message (e.g.,discovery solicitation message, discovery announcement message) from another WTRU (e.g., a remote WTRU and / or a relay of a remote WTRU). The WTRU may then determine whether to forward the discovery message received from another node (e.g., a remote WTRU) based on the property of its source and / or destination and the preferred property of the source and / or destination (e.g., the PLMN ID) associated with the discovery message, which may be indicated in the discovery message. Specifically, the WTRU may forward the discovery message if the discovery message’s source and / or destination does not support the preferred property of the source and / or destination indicated in the discovery message. Otherwise, if its source and / or destination supports the preferred property of the source and / or destination, the WTRU may respond to the discovery message (e.g., discovery solicitation message) from the WTRU to accept the relay service request. The property of a source and / or destination (e.g., a network node and / or a remote WTRU) may include one or any combination of the following:

[0101] The PLMN ID. For example, the WTRU may determine whether to forward the discovery message received from a WTRU (e.g., a remote WTRU) based on whether its current base station support the preferred PLMN ID indicated in the discovery message. Specifically, if the preferred PLMN ID is not supported by its current base station, the WTRU may forward the discovery solicitation message. Otherwise, the WTRU may not forward the discovery solicitation message. The WTRU may transmit a discovery response message to the WTRU transmitting the solicitation message (e.g., the remote WTRU).

[0102] The service may be supported by the node (e.g., sidelink and / or Uu positioning service, sensing service, multi-hop relay service, a relay service ID). A WTRU (e.g., remote WTRU) may indicate the preferred sidelink positioning support base station in the solicitation message. The WTRU (e.g., relay WTRU), which has a connection with a base station, may forward the discovery message if the current base station does not support sidelink positioning. Otherwise, the WTRU may transmit a discovery response message (e.g., to the remote WTRU).

[0103] The WTRU may receive a relay service ID indicated in the discovery solicitation message, in which each relay service ID may be associated with one relay service. The WTRU may then determine to response to the remote WTRU if its source and / or destination supports the relay service ID. Otherwise, the WTRU may forward the discovery solicitation message.

[0104] The feature supported by the cell (e.g., full-duplex, network energy saving, etc.). The WTRU may determine to forward the received discovery solicitation message if its current gNB does not support the featured indicated in the discovery message. Otherwise, the WTRU may response to the remote WTRU to accept the service request from the remote WTRU.

[0105] The QoS may be supported by the source and / or destination. The WTRU may receive the indication of the number of remaining hops from a WTRU (e.g., a relay WTRU and / or a remote WTRU). The WTRU may then respond to the discovery solicitation message if the number of remaining hops indicated in the discovery message is greater than the number of hops from the WTRU to the source and / or destination. Otherwise, the WTRU may discard the discovery solicitation message. Moreover, the WTRU may forward the discovery solicitation message to find another path to support the remote WTRU.

[0106] A WTRU (e.g., relay WTRU) may obtain the property of its source and / or destination. The WTRU may have a connection with a base station. The WTRU may obtain the property of the base station based on reading the SIB broadcasted by the base station. Additionally or alternatively, the WTRU may obtain the property of the base station based on a dedicated signaling (e.g., RRC) from the base station. Additionally or alternatively, the WTRU may obtain the property of the base station based on the signaling from a relay (e.g., U2N Relay). The WTRU may have a connection with a source and / or destination WTRU (e.g., a remote WTRU). The WTRU may obtain the property of the source and / or destination WTRU based on a signaling exchange such as NAS and / or PC5 RRC. Such signaling exchange may be conveyed during the discovery procedure, link establishment procedure, and / or regular information exchange procedure via NAS and / or PC5-RRC.

[0107] The WTRU may obtain a property associated with a source and / or destination. The WTRU may then determine the validity associated with the property of the source and / or destination. Specifically, the property associated with the source and / or destination may be valid of a period. After the validity period, the WTRU may consider the property associated with the source and / or destination as invalid.

[0108] FIG. 2 depicts examples of a wireless transmit / receive unit (WTRU) that determines whether to forward a discovery message for a remote WTRU based on a public land mobile network (PLMN). As shown in FIG. 2, the Relay UE1 204 may receive discovery solicitation message 208 from a remote WTRU 212 via a Relay UE2 216. In the discovery solicitation message, the remote WTRU 212 may indicate the preferred PLMN ID #x 220a-b. The Relay UE1 204, upon reception of the discovery solicitation message 208 from the Relay UE2 216, may determine whether to forward the discovery solicitation message 208 based on the indicated PLMN ID in the discovery solicitation message 208 and the PLMN ID 220a-b associated with its current gNB (e.g., PLMN ID #1 220a). Specifically, if the PLMN ID 220a-b indicated in the discovery solicitation message 208 is different from the PLMN ID 220a-b of its current gNB, the WTRU may forward the discovery solicitation message 208. Otherwise, if thePLMN ID 220a-b indicated in the discovery solicitation message 208 is the same as the PLMN ID 220a-b of its gNB, the WTRU may transmit the discovery response message to the remote WTRU 212 via the Relay UE2 216 to accept the requested relay service.

[0109] The WTRU may forward the set of detected remote WTRUs to the source and / or destination. The WTRU may have a connection with a source and / or destination (e.g., a remote WTRU and / or gNB) via zero, one or more relay WTRUs. The WTRU may monitor discovery message from other WTRU. The WTRU may then forward the set of detected remote WTRUs and its associated path to the gNB if its current source and / or destination can satisfy the preferred property of the source and / or destination, which may be indicated in the discovery message. The set of detected WTRUs and / or its associated path may be conveyed to the source and / or destination via NAS and / or RRC message.

[0110] A UE (e.g., an intermediate relay WTRU) may receive a discovery solicitation message from another WTRU (e.g., a remote WTRU and / or a relay WTRU). The WTRU may then determine whether to send the discovery response message to the WTRU transmitting the solicitation message based on one or any combination of the following:

[0111] Indication from its parent node (e.g., parent relay, gNB) to accept / reject a remote WTRU. For example, the WTRU may first indicate the detected remote WTRU and its associated path to the parent node (e.g., the parent relay, gNB). Such indication may be received via NAS and / or RRC message. The WTRU may then receive an indication (e.g., via NAS and / or RRC message) from the parent node (e.g., the parent relay, the gNB) of whether to accept / reject the remote WTRU. Upon reception of such indication from the parent node, the WTRU may then determine whether to transmit the discovery response message to the remote WTRU. Specifically, if the WTRU receives an indication to accept the remote WTRU from the parent node, the WTRU may transmit the discovery response message to the remote WTRU.Otherwise, if the WTRU receive an indication (e.g., via NAS and / or RRC) to reject the remote WTRU from the parent node, the WTRU may ignore the solicitation message from the remote WTRU. The WTRU may discard the solicitation message from the remote WTRU.

[0112] Whether the current source and / or destination satisfies the preferred source and / or destination property may be indicated in the discovery message. For example, the relay WTRU may transmit the discovery response message to the remote WTRU if the source and / or destination satisfies the preferred property of the source and / or destination indicated in the discovery solicitation message from the remote WTRU.

[0113] The WTRU (e.g., an intermediate relay WTRU) may first monitor discovery transmission from another WTRUs (e.g., a relay WTRU, a remote WTRU). The WTRU may then store the listof source and / or destination and / or associated path to the source and / or destination. The WTRU may indicate, in the discovery message, the property associated with each source and / or destination. The WTRU may then receive a discovery solicitation message from a remote WTRU. The discovery solicitation message may be received directly from the remote WTRU and / or via a relay WTRU. The WTRU may then indicate, in the discovery solicitation message, the preferred property of the source and / or destination. The WTRU may then determine whether to forward the discovery solicitation message based on whether it detected any source and / or destination satisfying the preferred property of the source and / or destination indicated in the discovery message. Specifically, the WTRU may forward the discovery message if it detected a source and / or destination satisfying the preferred property of the source and / or destination.

[0114] A WTRU may have a connection with a source and / or destination (e.g., a gNB, a remote WTRU). The WTRU may receive a discovery message (e.g., discovery announcement) from a relay WTRU. The WTRU may then determine whether to forward the discovery announcement message for the relay WTRU based on one or any combination of the following:

[0115] The source (e.g., the gNB) associated with the discovery message may be the service provider for the relay service. For example, a U2N relay may transmit a discovery announcement message to announce the relay service of the gNB as the source of the path.

[0116] The WTRU may have a connection with a cell / gNB. The WTRU may receive the discovery message from a relay WTRU. The discovery message may indicate the PLMN ID associated with the cell / gNB. The WTRU may determine whether to forward the discovery message based on the PLMN ID associated with the discovery message. The WTRU may forward the discovery message if the WTRU is associated with a different PLMN ID compared to the PLMN ID of its gNB. This approach may motivate the WTRU to offer relay service(s) to different PLMNs. The WTRU may not forward the discovery message if the WTRU is associated with different PLMN ID of its gNB. This approach may be motivated to enable the relay WTRU to support one PLMN ID associated with its current gNB only.

[0117] The WTRU may have a connection with a cell and / or gNB. The WTRU may receive the discovery message from a relay WTRU. The discovery message may indicate the cell ID and / or gNB associated with the discovery message. The WTRU may forward the discovery message if the cell ID and / or gNB is the same as its cell ID and / or gNB. Otherwise, the WTRU may not forward the discovery announcement message. The WTRU may forward the discovery message if the cell ID and / or gNB is different from its cell ID and / or gNB. Otherwise, the WTRU may not forward the discovery announcement message.

[0118] The WTRU may determine whether to forward the discovery announcement message for the Relay WTRU based on the transmitter of the discovery message. For example, the WTRU may determine whether to forward a discovery announcement message based on whether the transmitter of the discovery message is one of the relay WTRUs in its current path. Specifically, the WTRU may forward the discovery announcement message for a relay WTRU (e.g., an intermediate Relay, a U2N Relay) in its current path (e.g., its parent relay, the U2N Relay in its path). The WTRU may forward the discovery message. Otherwise, if the transmitter is not associated with one of the relay WTRUs in its current path, the WTRU may not forward the discovery announcement message.

[0119] The WTRU may determine whether to forward the discovery announcement message for the Relay WTRU based on the weighted-path value (e.g., the number of hops to the source and / or destination) associated with the discovery message. For example, the WTRU may receive a discovery announcement message associated with the same cell, gNB, and / or the PLMN ID of its current cell, gNB, and / or PLMN ID. The discovery announcement message may be associated with different path (e.g., different U2N relay). The WTRU may then determine to forward the discovery message if the weighted-path associated with the discovery message is smaller than the weighted-path of its current cell, gNB, and / or PLMN ID. The smaller weighted- path value may be associated with a better path (e.g., the path with smaller number of hops, the larger channel measurement of each hop).

[0120] Additionally or alternatively, the WTRU may determine to forward the discovery message if the difference between two weighted-path values. These may be paths associated with the discovery message and / or the current path of the WTRU greater than a (pre-)configured threshold. The threshold for delta weighted-path values and the parameters to calculate a weighted-path value may be (pre-)configured. For example, the WTRU may forward the discovery if the number of hops associated with the discovery message is smaller than the number of hops associated with its current path. Moreover, in case the number of hops associated with the discovery message is equal to the number of hops associated with its current path, the WTRU may forward the discovery message if the measured sidelink transmission associated with the discovery (e.g., sidelink-RSRP) is larger than a threshold and / or the difference between sidelink-RSRP associated with the discovery transmission and the current path is greater than a (pre-)configured threshold.

[0121] The WTRU may determine whether to forward the discovery announcement message for the Relay WTRU based on the stored path associated with the source and / or destination of the discovery message. For example, the WTRU may receive a discovery message fromanother WTRU. The WTRU may forward the discovery message if the discovery message is associated with one of the shortest paths to and / or from the source and / or destination. Specifically, the WTRU may be (pre-)configured to store a maximum number of shortest paths to each source and / or destination. Upon reception of a discovery message from a relay WTRU for a path, if the path is associated with one of the shortest paths to a source and / or destination, the WTRU may forward the discovery message. Otherwise, if the path may not be associated with one of the shortest paths to the source and / or destination, the WTRU may not forward the discovery message.

[0122] The weighted-path value of the path may determine the path length of each path. The WTRU may be (pre-)configured to forward the discovery for the shortest path associated with one source and / or destination. The WTRU may first detect and / or store the shortest path to the source and / or destination. The WTRU may then detect another path to the same source and / or destination, which is stored before. If the detected path is longer than the shortest path, the WTRU may not forward the discovery associated with the detected path. Otherwise, if the detected path is shorter than the stored shortest path, the WTRU may then forward the discovery associated with the detected path. The WTRU may then store the newly detected path.

[0123] The WTRU may be (pre-)configured to forward the discovery for the shortest path associated with a PLMN ID. The WTRU may first detect and store the shortest path to the PLMN ID (e.g., the PLMN ID associated with one gNB). The WTRU may then detect another path to the same PLMN ID (e.g., the path associated with another gNB), which is stored before. If the detected path is longer than the shortest path, the WTRU may not forward the discovery associated with the detected path. Otherwise, if the detected path is shorter than the stored shortest path, the WTRU may then forward the discovery associated with the detected path. The WTRU may then store the newly detected path to the PLMN ID.

[0124] The WTRU may receive a discovery message from a WTRU. The discovery message may indicate the information associated with the path to and / or from the source and / or destination. The WTRU may then determine the weighted-path value associated with the path to evaluate the quality of the path to a source and / or destination. The weighted-path value may be determined as a function of the number of hops to the source and / or destination and the channel measurement (e.g., sidelink-RSRP) associated with each hop.

[0125] The WTRU may monitor discovery message from other WTRUs. The WTRU may be (pre-)configured to store a maximum number of shortest paths to a source and / or destination. If the WTRU has stored maximum number of paths associated with one source and / ordestination, upon detection of a new path to the source and / or destination, the WTRU may then replace an existing path by a newly detected path.

[0126] A WTRU (e.g., remote WTRU) may receive a discovery message transmitted by another WTRU, in which the discovery message may indicate an associated path. The WTRU may first measure the sidelink channel (e.g., sidelink-RSRP) associated with the transmission from the discovery message for the path. The WTRU may then determine the validity associated with the detected path. Specifically, the WTRU may consider the path as valid within an elapsed time from the time the WTRU received the last discovery message of the path. The reception of the discovery message may be conditional on the measured sidelink transmission (e.g., sidelink- RSRP) being greater than a configured threshold. Additionally or alternatively, the WTRU may consider the path as invalid if it has received a discovery message from the path within an elapsed time. The validity time of a path may be (pre-)configured.

[0127] The WTRU may release the current path associated with the source and / or destination upon establishing the shorter path. The WTRU may receive the establishment request from a remote WTRU to set up the link between the remote WTRU to the source and / or destination. Upon establishment of the link to the source and / or destination associated with the shorter path compared to its current path, the WTRU may then send a message to the source and / or destination to release the current path. The WTRU may use the newly established path to the source and / or destination. The WTRU may establish a new path to the source and / or destination. The WTRU may release the current path to switch to the newly established path. Additionally or alternatively, the WTRU may maintain the current path and / or use both the current and / or newly established paths for transmission and / or reception with the source and / or destination.

[0128] FIG. 3 depicts a WTRU that determines whether to forward a discovery announcement message from another relay. As shown in FIG. 3, the Relay WTRU 304 may have a connection with the gNB1 320a via U2N Relayl 308 and / or Intermediate Relayl 312. The Relay WTRU 304 may receive discovery announcement messages 316a-d from multiple other WTRUs. For each received discovery announcement message 316a-d, the Relay WTRU 304 may determine whether to forward the discovery announcement message 316a-d. Specifically, the Relay WTRU 304 may first receive a discovery announcement message 316a-d from its parent node ( / .e., the Intermediate Relayl 312). The Relay WTRU 304 may then forward the discovery announcement message 316c for the Intermediate Relayl 312. The Relay WTRU 304 may forward the discovery announcement message 316c from Intermediate Relayl 312 without verifying the measured sidelink-RSRP. Specifically, the Relay WTRU 304 may forward thediscovery announcement message from its parent nodes regardless of the sidelink-RSRP measured for the discovery message. The Relay WTRU 304 may receive a discovery announcement message 316b from U2N Relay2 324, which may be shorter than its current path. The Relay WTRU 304 may then forward the discovery announcement message 316b associated with the U2N Relay2 324. The Relay WTRU 304 may receive a discovery message announcement message 316a associated with the Intermediate Relay3 328. However, this path may be longer than another path to the gNB1 320a. The WTRU may then discard and / or ignore the discovery message from the Intermediate Relay3 328. The Relay WTRU 304 may also receive a discovery announcement message 316d with from Intermediate Relay4 332. The Relay WTRU 304 may forward the discovery announcement message 316d from Intermediate Relay4 332 as it is associated with a different gNB (e.g., gNB2 320b).

[0129] A WTRU (e.g., parent relay WTRU) may transmit an indication to another WTRU (e.g., child Relay WTRU) to explicitly and / or implicitly request the other WTRU (e.g., child relay WTRU, an intermediate Relay WTRU) to stop / start transmission and / or reception of a discovery message. The WTRU may use one or any combination of the following message to convey the indication message: NAS, PC5-RRC, MAC-CE, and / or SCI, etc.

[0130] This approach may be applicable when the WTRU has established a connection (e.g., PC5 RRC connection) with the indicated WTRUs. The indicated WTRU, upon reception of an indication to start / stop discovery transmission and / or reception from the other WTRU (e.g., the parent relay WTRU), may then stop / start transmission and / or reception of discovery message. Specifically, the requesting WTRU may explicitly and / or implicitly indicate the other WTRU to start / stop discovery transmission and / or reception in one or any combination of the following events:

[0131] A WTRU may explicitly and / or implicitly indicate other WTRUs to start transmission and / or reception of discovery message. The WTRU (e.g., U2N relay, an intermediate relay, and / or a last relay) may experience RLF in the link between itself and the parent node. The WTRU may then indicate to another WTRU (e.g., a child node) to start transmission of discovery. Such indication may help the child node to find another path to the source (e.g., gNB).

[0132] The WTRU (e.g., U2N Relay, an intermediate relay, and / or a last relay) may experience channel degradation (e.g., sidelink-RSRP is smaller than a (pre-)configured threshold) with another node (e.g., with its child node and / or with its parent node) in the path. The WTRU may then indicate to another node to start transmission and / or reception of a discovery message. For example, if the WTRU experience channel degradation with the parent node, it may indicate tothe child node to start transmission and / or reception of the discovery message. Additionally or alternatively, if the WTRU experience channel degradation with the child node, the WTRU may indicate to the parent node to start transmission and / or reception of the discovery message.

[0133] A WTRU may explicitly and / or implicitly indicate to another WTRU to stop transmission and / or reception of a discovery message. The WTRU (e.g., an U2N relay) may have its load being greater than a configured threshold. The WTRU may then explicitly indicate the subsequent WTRUs (e.g., the WTRUs connecting to the network via the U2N relay itself and / or the child nodes and the WTRUs connecting to the child nodes) to stop transmitting a discovery message. Specifically, for Model A discovery, the WTRU may request the subsequent WTRUs not to transmit discovery announcement message to announce the discovery service. Alternatively, for Model B discovery, the WTRU may request the subsequent WTRUs not to transmit the discovery response message from a remote WTRU. The indicated WTRU, upon reception of the indication from the other WTRU, may then start / stop transmission and / or reception of the discovery message.

[0134] A WTRU (e.g., U2N Relay) may first experience a bad channel condition between itself and the parent / child node. The WTRU may then indicate the other WTRU (e.g., its parent or child node) to start transmission and / or reception of discovery message. When the channel condition between itself and the parent / child node is getting better (e.g., when sidelink-RSRP is greater than a (pre-)configured threshold), the WTRU may then indicate to the child / parent node to stop transmission and / or reception of discovery message.

[0135] FIG. 4 depicts degradation and / or radio link failure (RLF) in one hop. As shown in FIG. 4, the remote WTRU 404 may have a communication path to the gNB1 420 via U2N Relay 408, U2U Relayl 412, and / or U2U Relay2 416. The U2U Relayl 412 may experience RLF and / or channel degradation in the link between itself and the U2N Relay 408. The remote WTRU 404 may then indicate such event to the U2U Relay2 416. The U2U Relay2 416, upon reception of the indication from the U2U Relayl 412, may then trigger discovery transmission and / or reception. When the channel between the U2U Relayl 412 and / or U2N Relay 408 getting better (e.g., sidelink-RSRP is greater than a (pre-)configured threshold), the U2U Relayl 412 may then indicate to the U2U Relay2 416. U2U Relay2 416, upon reception of such indication from U2U Relayl 412, may then stop transmission and / or reception of discovery message.

[0136] The WTRU may release one or more remote WTRUs upon changing the path to the source. A WTRU may determine to change the path to the source and / or destination. Specifically, the WTRU may change the path due to one or any combination of the followingevent: the WTRU may switch between sidelink and / or Uu or between Uu and / or sidelink; and / or the WTRU handover to another cell / gNB.

[0137] Upon the property of the path change, the WTRU may then determine whether the new path satisfies the preferred path (e.g., number of hops, the PLMN ID, and / or the QoS requirement) for each connected remote WTRU. If the preferred path of one remote WTRU is not satisfied, the WTRU may then send such indication to the remote WTRU. The WTRU may release the connection with the remote WTRU. The WTRU may reconfigure the WTRU with a different configuration. This different configuration may be associated with the new path. The WTRU may also send the new path information to the remote WTRU which may help the WTRU to be aware of the current path status.

[0138] FIG. 5 depicts example scenarios for path switching. As shown in FIG. 5, the remote WTRU 504 may have a connection with gNB1 520b via U2U Relayl 512, U2U Relay2 516, and / or U2N Relay 508. The remote WTRU 504 may support the relay service of a maximum of four hops. The U2N Relay 508 may switch from Uu to sidelink. The U2N relay 508 may indicate to the remote WTRU 504 to release the remote WTRU 504 as the number of hops in the path from the remote WTRU 504 to the gNB 520a-c (e.g., now it is five hops) is greater than the maximum allowed number of hops to the network (e.g., four hops).

[0139] The U2U Relayl 512 may switch to another gNB (e.g., gNB2 520a) in the same PLMN. The new gNB (e.g., gNB2 520a) may be the preferred PLMN ID of the remote WTRU. The number of hops in the new path is still the same. The WTRU may then decide to keep the release and inform the WTRU of the new path.

[0140] A WTRU (e.g., intermediate relay having established connection with the gNB having associated cell property), upon reception of a discovery solicitation message from another WTRU (e.g., a remote WTRU) may determine which discovery message to transmit (e.g., discovery solicitation forwarding message and / or discovery response message). The determination may be based on whether the requested source and / or destination property (e.g., PLMN ID, number of hops supported, QoS supported) indicated in the discovery message is satisfied by the current source and / or destination property of the WTRU (e.g., the current gNB).

[0141] The WTRU may establish a connection with a cell having associated cell property (e.g., PLMN ID) via one or more relays. The WTRU may receive a discovery solicitation message from other WTRU (e.g., remote WTRU), which has an associated preferred source and / or destination property (e.g., PLMN ID).

[0142] The WTRU may determine which discovery message to transmit based on whether the source and / or destination property (e.g., PLMN ID) of its current source and / or destinationsatisfies preferred source and / or destination property (e.g., PLMN ID), indicated in the received discovery message. If the current source and / or destination property (e.g., PLMN IDs) does not satisfy the preferred source and / or destination property indicated in the discovery message, the WTRU may forward the discovery solicitation message. Otherwise, the WTRU may transmit the discovery response message and indicate its current path in the response message.

[0143] In other words, an initial (e.g., first) WTRU may receive, from another (e.g., second) WTRU, a discovery message may indicate a preferred source property associated with a source property of a cell and / or a preferred destination property associated with a destination property of the cell. The initial WTRU may determine whether the source property satisfies the preferred source property or the destination property satisfies the preferred destination property. The initial WTRU may send, a different node, a second discovery message based on the source property not satisfying the preferred source property or the destination property not satisfying the preferred destination property. The node may be a remote WTRU, a relay WTRU, or a network entity.

[0144] The WTRU may transmit the determined discovery message. This may enable the WTRU to selectively transmit discovery message. Selective transmission may minimize the signaling overhead of discovery transmission while still maintaining the QoS associated with discovery transmission.

[0145] A WTRU (e.g., intermediate relay having established connection with the gNB associated with an PLMN ID), upon reception of a discovery announcement message from another WTRU (e.g., a remote WTRU) may determine whether to forward a received discovery announcement from a relay WTRU based the weighted-path value (e.g., number of hops), the transmitter of the message, and / or the source (e.g., gNB) of the path in the discovery message.

[0146] The WTRU may establish a connection with a gNB via one or more relays. The WTRU may be (pre-)configured with the parameters to calculate a weighted-path value of a path. For example, the weighted-path value of a path may be a function of the number of hops to the source (e.g., gNB) and / or the sidelink-measurement (e.g., SL-RSRP) associated with the discovery announcement message.

[0147] The WTRU may be (pre-)configured with the delta weighted-path value threshold between the detected path and current path to forward discovery message. For example, the WTRU may forward a discovery announcement message in different path associated with the same gNB if the delta weighted-path value is greater than zero.

[0148] The WTRU may receive a discovery announcement message from another WTRU (e.g., remote WTRU). The other WTRU may have the path information including the transmitter and / or the source (e.g., gNB) associated with the discovery message.

[0149] The WTRU may determine whether to forward a received discovery announcement from a relay WTRU based on the weighted-path value (e.g., number of hops), the transmitter of the message, and / or the source (e.g., gNB, peer remote WTRU) of the path in the discovery message. If the gNB associated with the discovery message is different from its gNB, the WTRU may forward the discovery announcement message. Otherwise, if the gNB associated with the discovery message is also the WTRU’s gNB, then the transmitter may be one of the relays in its path (e.g., the parent relay), that may forward the discovery announcement message. Otherwise, the WTRU may determine the weighted-path values (e.g., number of hops) associated with its current and / or detected paths, and / or determine to forward the discovery announcement message if the delta weighted-path values between the detected paths is larger than the configured threshold.

[0150] The WTRU may transmit the determined forward discovery announcement message. This may enable the WTRU to selectively transmit a discovery message. The discovery message may minimize the signaling overhead of discovery transmission while still maintaining the QoS associated with discovery transmission.

[0151] A WTRU (e.g., an intermediate relay) may indicate its child node to start / stop discovery transmission and / or reception (e.g., using PC5 RRC) based on the channel measurement between itself and the parent node (e.g., U2N Relay and / or gNB) and / or an indication from its parent node.

[0152] The WTRU may establish a multi-hop relay connection between one or more sources (e.g., gNB) and / or one or more destinations (e.g., remote WTRUs). The WTRU may be (preconfigured with SL-RSRP thresholds (e.g., first SL-RSRP threshold to start discovery and / or second SL-RSRP threshold to stop discovery transmission and / or reception). The WTRU may perform measurement in the channel between itself and the parent relay node.

[0153] The WTRU may indicate its child node to start / stop discovery transmission and / or reception (e.g., using PC5 RRC) based on the channel measurement between itself and the parent node (e.g., U2N Relay, gNB) and / or an indication from its parent node. If the WTRU receives an indication from the parent node to start / stop discovery transmission, the WTRU may indicate the child node to start / stop discovery transmission. If the measured SL-RSRP is greater than the first threshold, the WTRU may indicate the child node to start discovery transmission and / or reception. If the measured SL-RSRP is smaller or larger than the firstthreshold, the WTRU may indicate the child node to stop discovery transmission and / or reception.

[0154] The WTRU may transmit the determined indication (e.g., using PC5 RRC) to the child node. This may enable the WTRU to better prepare for path change to and / or reduce service interruption time when RLF happens in the path. This may enable the network to reduce signaling overhead of discovery transmission as the WTRU may not need to transmit / receive discovery unnecessarily.

[0155] A WTRU (e.g., an intermediate relay), upon selecting a different path to the source, destination, and / or network, may transmit a release indication to the child node to release the remote WTRUs. The remote WTRU may have the required path property that may not be satisfied by the new path property (e.g., number of hops and / or the PLMN ID).

[0156] The WTRU may establish a multi-hop relay connection between one or more sources (e.g., gNB) and one or more remote WTRUs. Each remote WTRU may have an associated required path property (e.g., number of hops and / or PLMN ID).

[0157] The WTRU may select a different path to a source (e.g., a gNB). For example, the WTRU may select a different path due to handover, path switch, and / or relay reselection.

[0158] The WTRU may determine the set of remote WTRUs to release the connection with itself based on whether the required path property is satisfied by the new path. If the new path property (e.g., number of hops to the gNB) cannot satisfy the required path property of the remote WTRU, the WTRU may include the remote WTRU in the set of the release remote WTRU.

[0159] The WTRU may transmit one or more indications (e.g., PC5 RRC) to the determined remote WTRUs to release the connection. This may enable the WTRU to guarantee the QoS of the relay service by keeping the remote WTRU with satisfied QoS and / or releasing the remote WTRUs with unsatisfied QoS. This may enable the WTRU to reselect a different path with satisfied QoS.

Claims

CLAIMS1. A first wireless transmit / receive unit (WTRU) comprising: a processor and a memory, the processor configured to: receive, from a second WTRU, a first discovery message, wherein the first discovery message indicates a preferred source property associated with a source property of a cell or a preferred destination property associated with a destination property of the cell; determine whether the source property satisfies the preferred source property, or the destination property satisfies the preferred destination property; and send, to the second WTRU, a second discovery message based on the source property satisfying the preferred source property or the destination property satisfying the preferred destination property.

2. A method implemented by a first wireless transmit / receive unit (WTRU), the method comprising: receiving, from a second WTRU, a first discovery message, wherein the first discovery message indicates a preferred source property associated with a source property of a cell, or a preferred destination property associated with a destination property of the cell; determining whether the source property satisfies the preferred source property or the destination property satisfies the preferred destination property; and sending, to the second WTRU, a second discovery message based on the source property satisfying the preferred source property or the destination property satisfying the preferred destination property.

3. The first WTRU of claim 1 or the method of claim 2, wherein the first discovery message is a discovery solicitation message.

4. The first WTRU of claim 1 or the method of claim 2, wherein the second discovery message is a discovery response message.

5. The first WTRU of claim 1 or the method of claim 2, wherein the source property or the destination property comprises one or more of a public land mobile network (PLMN) identifier, a number of hops supported by the second WTRU, or a quality of service (QoS) supported by the second WTRU.

6. The first WTRU of claim 1 or the method of claim 2, wherein the first discovery message comprises one or more indications, wherein the one or more indications comprise an indication of the weighted path value of the path associated with the first discovery message, a public land mobile network (PLMN) identifier, an indication of a stored path, an indication of a measurement associated with the first discovery message, or an indication from a node.

7. The first WTRU of claim 6 or the method of claim 6, wherein the node is a remote WTRU, a relay WTRU, or a network entity.

8. The first WTRU of claim 6 or the method of claim 6, wherein the second discovery message comprises at least one of the one or more indications that comprise the first discovery message and an indication that the source property does satisfy the preferred source property or the destination property does satisfy the preferred destination property.

9. The first WTRU of claim 1 or the method of claim 2, wherein the second discovery message comprises an indication of the current path of the first WTRU.

10. The first WTRU of claim 1 , wherein the processor is further configured to: send, to the second WTRU, a message indicating that the first WTRU has accepted the first discovery message.

11. The first WTRU of claim 1 , wherein the processor is further configured to: receive, from the second WTRU, an indication to send the second discovery message to the second WTRU.

12. The method of claim 2, further comprising: sending, to the second WTRU, a message indicating that the first WTRU has accepted the first discovery message.

13. The method of claim 2, further comprising: receiving, from the second WTRU, an indication to send the second discovery message to the second WTRU.

14. A first wireless transmit / receive unit (WTRU) comprising:a processor and a memory, the processor configured to: receive, from a second WTRU, a first discovery message, wherein the first discovery message indicates a preferred source property associated with a source property of a cell or a preferred destination property associated with a destination property of the cell; determine whether the source property satisfies the preferred source property, or the destination property satisfies the preferred destination property; and send, to a node, a second discovery message based on the source property not satisfying the preferred source property or the destination property not satisfying the preferred destination property.

15. A method implemented by a first wireless transmit / receive unit (WTRU), the method comprising: receiving, from a second WTRU, a first discovery message, wherein the first discovery message indicates a preferred source property associated with a source property of a cell, or a preferred destination property associated with a destination property of the cell; determining whether the source property satisfies the preferred source property or the destination property satisfies the preferred destination property; and sending, to a node, a second discovery message based on the source property not satisfying the preferred source property or the destination property not satisfying the preferred destination property.

16. The first WTRU of claim 14 or the method of claim 15, wherein the first discovery message is a discovery solicitation message.

17. The first WTRU of claim 14 or the method of claim 15, wherein the second discovery message is a discovery response message.

18. The first WTRU of claim 14 or the method of claim 15, wherein the source property or the destination property comprises one or more of a public land mobile network (PLMN) identifier, a number of hops supported by the second WTRU, or a quality of service (QoS) supported by the second WTRU.

19. The first WTRU of claim 14 or the method of claim 15, wherein the node is a remote WTRU, a relay WTRU, or a network entity.

20. The first WTRU of claim 14 or the method of claim 15, wherein the first discovery message comprises one or more indications, wherein the one or more indications comprise an indication of the weighted path value of the path associated with the first discovery message, a public land mobile network (PLMN) identifier, an indication of a stored path, an indication of a measurement associated with the first discovery message, or an indication from another node.

21. The first WTRU of claim 20 or the method of claim 20, wherein the second discovery message comprises at least one of the one or more indications that comprise the first discovery message and an indication that the source property does not satisfy the preferred source property or the destination property does not satisfy the preferred destination property.

22. The first WTRU of claim 14 or the method of claim 15, wherein the second discovery message comprises an indication of the current path of the first WTRU.

23. The first WTRU of claim 14, wherein the processor is further configured to: send, to the second WTRU, a message indicating that the first WTRU has accepted the first discovery message.

24. The first WTRU of claim 14, wherein the processor is further configured to: receive, from the node, an indication to send the second discovery message to the second WTRU.

25. The method of claim 15, further comprising: sending, to the second WTRU, a message indicating that the first WTRU has accepted the first discovery message.

26. The method of claim 15, further comprising: receiving, from the node, an indication to send the second discovery message to the second WTRU.

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