Wireless transmit / receive unit (WTRU) and method of implementing same

Abstract

A wireless transmit / receive unit (WTRU) and a method of implementing the same are provided. The method comprises: receiving one or more transmissions from a second WTRU, the one or more transmissions comprising any one of one or more data transmissions and one or more discovery transmissions; selecting one or more measured signal characteristics for one of (i) the one or more data transmissions and (ii) the one or more discovery transmissions based on: (i) the one or more measured signal characteristics for the one or more data transmissions and (ii) a priority of at least one of the one or more measurement signal characteristics of the one or more discovery transmissions; availability of the one or more measured signal characteristics of the one or more data transmissions; and whether the first WTRU is currently receiving and currently scheduled to receive any one of one or more data transmissions from the second WTRU; and performing relay reselection based on the selected one or more measurement signal characteristics failing to meet one or more thresholds.

Description

[0001] This application is a divisional application of the invention patent application with the application date of June 4, 2021, application number: 202180047065.X, and invention name: "Methods, architectures, devices and systems involving relay and path selection and reselection".

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of priority to (i) U.S. Provisional Patent Application No. 63 / 034,980 filed on June 4, 2020, (ii) U.S. Provisional Patent Application No. 63 / 091,883 filed on October 14, 2020, and (iii) U.S. Provisional Patent Application No. 63 / 136,550 filed on January 12, 2021, each of which is incorporated herein by reference. Background Art

[0004] The present application relates to wired and / or wireless communications, including, for example, performing relay selection and / or reselection, path selection and / or reselection, and any of the processes combined with relay selection and / or reselection and path selection and / or reselection. Summary of the invention

[0005] In one aspect, the present application provides a method implemented in a first wireless transmit / receive unit WTRU, the method comprising: receiving one or more transmissions from a second WTRU, wherein the one or more transmissions include any one of one or more data transmissions and one or more discovery transmissions; selecting one or more measurement signal characteristics of (i) the one or more data transmissions and (ii) one of the one or more discovery transmissions based on: (i) the one or more measurement signal characteristics of the one or more data transmissions and (ii) the priority of at least one of the one or more measurement signal characteristics of the one or more discovery transmissions; the availability of the one or more measurement signal characteristics of the one or more data transmissions; and whether the first WTRU is currently receiving and currently scheduled to receive any one of the one or more data transmissions from the second WTRU; and performing relay reselection based on the failure of the selected one or more measurement signal characteristics to meet one or more thresholds.

[0006] On the other hand, the present application provides a first wireless transmit / receive unit WTRU, the first WTRU including a circuit, the circuit including a transmitter, a receiver, a processor and a memory, the first WTRU being configured to: receive one or more transmissions from a second WTRU, wherein the one or more transmissions include any one of one or more data transmissions and one or more discovery transmissions; select one or more measurement signal characteristics of (i) the one or more data transmissions and (ii) one of the one or more discovery transmissions based on: (i) the priority of the one or more measurement signal characteristics of the one or more data transmissions and (ii) at least one of the one or more measurement signal characteristics of the one or more discovery transmissions; the availability of the one or more measurement availability of the one or more measurement signal characteristics of the one or more data transmissions; and whether the first WTRU is currently receiving and currently scheduled to receive any one of the one or more data transmissions from the second WTRU; and perform relay reselection based on the failure of the selected one or more measurement signal characteristics to meet one or more thresholds. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] A more detailed understanding can be obtained from the following detailed description, which is given by way of example in conjunction with its accompanying drawings. As with the detailed description, the figures in such drawings are examples. Therefore, the drawings and specific embodiments should not be considered limiting, and other equally effective examples are possible and contemplated. In addition, like reference numerals ("ref.") in the drawings indicate similar elements, and wherein:

[0008] Figure 1A is a system diagram illustrating an exemplary communication system;

[0009] Figure 1B It shows that Figure 1A A system diagram of an exemplary wireless transmit / receive unit (WTRU) for use within the communication system shown;

[0010] Figure 1C It shows that Figure 1A A system diagram of an exemplary radio access network (RAN) and an exemplary core network (CN) used within the illustrated communication system;

[0011] Figure 1D It shows that Figure 1A A system diagram of an additional exemplary RAN and an additional exemplary CN used within the illustrated communication system;

[0012] Figure 2 is a block diagram illustrating an exemplary communication system including a relay WTRU;

[0013] Figure 3An exemplary transmission behavior of a direct communication message is shown;

[0014] Figure 4 An exemplary path selection process is shown;

[0015] Figure 5 An example of sidelink measurements associated with a path is shown;

[0016] Figure 6 is a flow chart illustrating an exemplary process for performing path selection or path reselection;

[0017] Figure 7 is a flow chart illustrating an exemplary process for performing measurement value reporting;

[0018] Figure 8 is a flow chart illustrating an exemplary process for performing relay selection or reselection; and

[0019] Fig. 9 is a flow chart illustrating an exemplary process for performing message forwarding. DETAILED DESCRIPTION

[0020] In the following detailed description, many specific details are set forth to provide a thorough understanding of the embodiments and / or examples disclosed herein. However, it should be understood that such embodiments and examples can be put into practice without some or all of the specific details set forth herein. In other cases, well-known methods, procedures, components and circuits are not described in detail to avoid blurring the following description. In addition, the embodiments and examples not specifically described herein can be put into practice in place of the embodiments and other examples explicitly, implicitly and / or inherently described, disclosed or otherwise provided (collectively referred to as "providing") herein, or put into practice in combination with these embodiments and examples. Although various embodiments are described and / or claimed herein, wherein devices, systems, equipment, etc. and / or any of their elements perform operations, processes, algorithms, functions, etc. and / or any part thereof, it should be understood that any embodiments described herein and / or protected by the claims assume that any device, system, equipment, etc. and / or any of their elements are configured to perform any operations, processes, algorithms, functions, etc. and / or any part thereof.

[0021] Exemplary Communication System

[0022] The methods, devices, and systems provided herein are well suited for communications involving both wired and wireless networks. Wired networks are well known. Figures 1A to 1DAn overview of various types of wireless devices and infrastructure is provided, wherein various elements of the network can utilize the methods, apparatuses, and systems provided herein, perform the methods, apparatuses, and systems provided herein, be arranged according to the methods, apparatuses, and systems provided herein, and / or be adapted and / or configured for the methods, apparatuses, and systems provided herein.

[0023] Figure 1A 1 is a diagram of an exemplary communication system 100 in which one or more disclosed embodiments may be implemented. The exemplary communication system 100 is provided for illustration purposes only and does not limit the disclosed embodiments. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc. to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content through sharing of system resources (including wireless bandwidth). For example, the communication system 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), zero tail (ZT) unique word (UW) discrete Fourier transform (DFT) spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multi-carrier (FBMC), etc.

[0024] like Figure 1AAs shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104 / 113, a core network (CN) 106 / 115, a public switched telephone network (PSTN) 108, the Internet 110 and other networks 112, but it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d (any of which may be referred to as a “station” and / or “STA”) may be configured to transmit and / or receive wireless signals and may include (or be) a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smart phone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated process chain environment), a consumer electronic device, a device operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a WTRU.

[0025] The communication system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device that is configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to, for example, facilitate access to one or more communication networks, such as the CN 106 / 115, the Internet 110, and / or the network 112. By way of example, the base stations 114a, 114b may be any of a base transceiver station (BTS), a Node B (NB), an evolved Node B (eNB), a Home Node B (HNB), a Home evolved Node B (HeNB), a gNode B (gNB), an NR Node B (NRNB), a site controller, an access point (AP), a wireless router, and the like. Although the base stations 114a, 114b are each depicted as a single element, it should be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0026] Base station 114a may be part of RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as base station controllers (BSC), radio network controllers (RNC), relay nodes, etc. Base station 114a and / or base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies (which may be referred to as cells (not shown)). These frequencies may be in a licensed spectrum, an unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage of wireless services to a specific geographic area, which may be relatively fixed or may change over time. A cell may be further divided into cell sectors. For example, a cell associated with base station 114a may be divided into three sectors. Therefore, in an embodiment, base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In an embodiment, base station 114a may employ multiple-input multiple-output (MIMO) technology and may utilize multiple transceivers for each or any sector of the cell. For example, beamforming may be used to transmit and / or receive signals in a desired spatial direction.

[0027] 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).

[0028] More specifically, as noted above, the communication system 100 may be a multiple access system and may employ one or more channel access schemes such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base station 114a in the RAN 104 / 113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may use Wideband CDMA (WCDMA) to establish the air interface 116. WCDMA may include communication protocols such as High Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed ​​Downlink Packet Access (HSDPA) and / or High Speed ​​Uplink Packet Access (HSUPA).

[0029] 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 Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-A Pro).

[0030] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as 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), GSM Enhanced Data Rates for Evolution (EDGE), GSM EDGE (GERAN), etc.

[0031] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR radio access that may establish the air interface 116 using New Radio (NR).

[0032] 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 example using dual connectivity (DC) principles. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., eNBs and gNBs).

[0033] 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 (Wi-Fi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), GSM Enhanced Data Rates for Evolution (EDGE), GSM EDGE (GERAN), etc.

[0034] Figure 1AThe base station 114b in may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in a local area such as a business location, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, and the like. In an 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 an embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish any of a microcell, a picocell, or a femtocell. As Figure 1A As shown, base station 114b may have a direct connection to Internet 110. Thus, base station 114b may not need to access Internet 110 via CN 106 / 115.

[0035] The RAN 104 / 113 may be in communication with the CN 106 / 115, which may be any type of network configured to provide voice, data, applications and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, delay requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not described in detail in the specification, the CN 106 / 115 may be configured to provide voice, data, applications and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. Figure 1A Although not shown in the figure, it will be appreciated that the RAN 104 / 113 and / or the CN 106 / 115 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 / 113 or a different RAT. For example, in addition to being connected to the RAN 104 / 113, which may utilize NR radio technology, the CN 106 / 115 may also be in communication with another RAN (not shown) that employs any of GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or Wi-Fi radio technologies.

[0036] The CN 106 / 115 may also act as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and the Internet Protocol (IP) in the TCP / IP Internet protocol suite. The networks 112 may include wired or wireless communication networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 / 114 or a different RAT.

[0037] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks via different wireless links). Figure 1A The illustrated WTRU 102c may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0038] Figure 1B 1 is a system diagram of an exemplary WTRU 102. The exemplary WTRU 102 is provided for illustration purposes only and is not intended to limit the disclosed embodiments. Figure 1B As shown, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136 and other peripherals 138. It will be appreciated that the WTRU 102 may include any subcombination of the foregoing elements while remaining consistent with an embodiment.

[0039] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functions that enable the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. Although Figure 1B The processor 118 and the transceiver 120 are depicted as separate components, but it is understood that the processor 118 and the transceiver 120 may be integrated together, for example, in an electronic package or chip.

[0040] The transmit / receive element 122 may be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) via an air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In one embodiment, the transmit / receive element 122 may be a transmitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In an embodiment, the transmit / receive element 122 may be configured to transmit and receive both RF signals and optical signals. It should be understood that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0041] Furthermore, although the transmit / receive element 122 is Figure 1B 1 as a single element, the WTRU 102 may include any number of transmit / receive elements 122. For example, 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.

[0042] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and to demodulate signals received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. For example, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0043] The processor 118 of the WTRU 102 may be coupled to a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit) and may receive user input data therefrom. The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from and store data in any type of suitable memory, such as a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from and store data in a memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0044] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control power to other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0045] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or in lieu of the information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by any suitable location-determination method while remaining consistent with an embodiment.

[0046] The processor 118 may also be coupled to other peripherals 138, which may include one or more software modules / units and / or hardware modules / units that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (e.g., for photos or videos), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, module, a frequency modulation (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, etc. Peripheral device 138 may include one or more sensors, which may be one or more of the following: a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor; an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0047] The WTRU 102 may include a full-duplex radio for which transmission and reception of some or all signals (e.g., associated with specific subframes for UL (e.g., for transmission) and downlink (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit for reducing and / or substantially eliminating self-interference via hardware (e.g., choke) or via signal processing performed by a processor (e.g., a separate processor (not shown) or via the processor 118). In one embodiment, the WTRU 102 may include a half-duplex radio for which transmission and reception of some or all signals (e.g., associated with specific subframes for UL (e.g., for transmission) or downlink (e.g., for reception)) may be concurrent and / or simultaneous.

[0048] Figure 1C 1 is a system diagram of the RAN 104 and the CN 106 according to another embodiment. As described above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, and 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0049] The RAN 104 may include evolved Node-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of evolved Node-Bs while remaining consistent with an embodiment. The evolved Node-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the evolved Node-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the evolved Node-B 160a, for example, may use multiple antennas to transmit wireless signals to, and receive wireless signals from, the WTRU 102a.

[0050] Each of the evolved Node Bs 160a, 160b, and 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, user scheduling in uplink (UL) and / or downlink (DL), etc. Figure 1C As shown, the eNode-Bs 160a, 160b, 160c may communicate with each other via an X2 interface.

[0051] Figure 1C The illustrated core network 106 may include a mobility management gateway (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway 166. While each of the foregoing elements is depicted as being part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than a CN operator.

[0052] The MME 162 may be connected to each of the evolved Node-Bs 160a, 160b, and 160c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, etc. The MME 162 may also provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM or WCDMA.

[0053] The SGW 164 may be connected to each of the evolved Node-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may also perform other functions, such as anchoring a user plane during inter-evolved Node-B handovers, triggering paging and / or mobile termination when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, and the like.

[0054] The SGW 164 may also be connected to the PDN Gateway 166, which may provide the WTRUs 102a, 102b, and 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.

[0055] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may be in communication with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired or wireless networks owned and / or operated by other service providers.

[0056] Although the WTRU Figures 1A to 1D Although described as a wireless terminal, it is contemplated that in certain representative embodiments such a terminal may (eg, temporarily or permanently) employ a wired communications interface with a communications network.

[0057] In a representative embodiment, the other network 112 may be a WLAN.

[0058] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for a BSS and one or more stations (STAs) associated with the AP. The AP may have access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic to and / or carries traffic away from the BSS. Traffic originating from outside the BSS and leading to the STA may be reached by the AP and may be delivered to the STA. Traffic originating from the STA and leading to a destination outside the BSS may be sent to the AP to be delivered to the corresponding destination. Traffic between STAs within the BSS may be sent by the AP, for example, wherein the source STA may send traffic to the AP, and the AP may deliver the traffic to the destination STA. Traffic between STAs within the BSS may be considered and / or referred to as point-to-point traffic. Point-to-point traffic may be sent between the source and destination STAs (e.g., directly between them) using a direct link setup (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunnel DLS (TDLS). A WLAN using an independent BSS (IBSS) mode may not have an AP, and STAs (eg, all STAs) within or using the IBSS may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad-hoc" communication mode.

[0059] When using the 802.11ac infrastructure operation mode or a similar operation mode, 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., a 20 MHz wide bandwidth) or a width dynamically set via signaling. The primary channel may be an operating channel of the BSS and may be used by the STA to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access / collision avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. For CSMA / CA, a STA (e.g., each STA) (including the AP) may 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.

[0060] High throughput (HT) STAs may communicate using a 40 MHz wide channel, for example, via a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0061] Very high throughput (VHT) STA can support 20MHz, 40MHz, 80MHz and / or 160MHz wide channels. 40MHz and / or 80MHz channels can be formed by combining continuous 20MHz channels. A 160MHz channel can be formed by combining 8 continuous 20MHz channels, or by combining two non-continuous 80MHz channels (this can be called 80+80 configuration). For the 80+80 configuration, after channel coding, the data can pass through a segment parser that can divide the data into two streams. Each stream can be processed by inverse fast Fourier transform (IFFT) and time domain processing separately. These streams can be mapped to two 80MHz channels, and data can be transmitted by transmitting STA. At the receiver of the receiving STA, the above-mentioned operation for the 80+80 configuration can be reversed, and the combined data can be sent to the medium access control (MAC).

[0062] 802.11af and 802.11ah support operating modes below 1GHz. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah relative to those used in 802.11n and 802.11ac. 802.11af supports 5MHz, 10MHz, and 20MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support meter type control / machine type communication (MTC), such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support for (e.g., only support for) certain bandwidths and / or limited bandwidths. MTC devices may include batteries with battery life above a threshold (e.g., to maintain very long battery life).

[0063] WLAN systems that can support multiple channels and channel bandwidths such as 802.11n, 802.11ac, 802.11af, and 802.11ah include channels that can be designated as primary channels. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA (which supports the minimum bandwidth operating mode) from all STAs operating in the BSS. In the example of 802.11ah, for STAs (e.g., MTC-type devices) that support (e.g., only support) 1MHz mode, the primary channel may be 1MHz wide, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) settings may depend on the state of the primary channel. If the primary channel is busy, for example, because a STA (supporting only the 1MHz operating mode) is transmitting to the AP, the entire available frequency band may be considered busy even if most of the frequency bands remain idle and may be available.

[0064] In the United States, the available frequency band for 802.11ah is 902MHz to 928MHz. In South Korea, the available frequency band is 917.5MHz to 923.5MHz. In Japan, the available frequency band is 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz, depending on the country code.

[0065] Figure 1D1 is a system diagram showing the RAN 113 and the CN 115 in accordance with an embodiment. As noted above, the RAN 113 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0066] 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 to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. In an embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, the gNBs 180a, 180b may utilize beamforming to transmit signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a may, for example, 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 techniques. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on an unlicensed spectrum, while the remaining component carriers may be on a licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) techniques. For example, the WTRU 102a may receive coordinated transmissions from the gNB 180a and the gNB 180b (and / or the gNB 180c).

[0067] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with scalable parameter sets. For example, OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or Transmission Time Intervals (TTIs) of varying or scalable lengths (e.g., containing varying numbers of OFDM symbols and / or varying absolute time lengths over time).

[0068] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c while also not accessing other RANs (e.g., such as the eNodeBs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may use one or more of the gNBs 180a, 180b, 180c as mobility anchor points. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate or connect with the gNBs 180a, 180b, 180c while also communicating or connecting with other RANs, such as the eNode-Bs 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNode-Bs 160a, 160b, 160c may serve as mobility anchors for the WTRUs 102a, 102b, 102c, and the gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0069] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and / or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards a user plane function (UPF) 184a, 184b, routing of control plane information towards an access and mobility management function (AMF) 182a, 182b, etc. Figure 1D As shown, gNBs 180a, 180b, and 180c may communicate with each other via an Xn interface.

[0070] Figure 1DThe illustrated CN 115 may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and possibly at least one data network (DN) 185a, 185b. Although each of the foregoing elements is depicted as part of the CN 115, it should be understood that any of these elements may be owned and / or operated by an entity other than a CN operator.

[0071] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c via the N2 interface in the RAN 113 and may serve as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRU 102a, 102b, 102c, support of network slicing (e.g., handling of different packet data unit (PDU) sessions with different requirements), selecting a specific SMF 183a, 183b, management of registration areas, termination of NAS signaling, mobility management, etc. The AMF 182a, 182b may use network slicing to customize CN support for the WTRU 102a, 102b, 102c, for example, based on the type of services used by the WTRU 102a, 102b, 102c. For example, different network slices may be established for different use cases, such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for MTC access, etc. The AMF 162 may provide a control plane function for switching between the RAN 113 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-APro, and / or non-3GPP access technologies, such as Wi-Fi.

[0072] The SMF 183a, 183b may be connected to the AMF 182a, 182b in the CN 115 via the N11 interface. The SMF 183a, 183b may also be connected to the UPF 184a, 184b in the CN 115 via the N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b, and configure traffic routing through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notification, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0073] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, e.g., to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, etc.

[0074] 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 other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In an embodiment, the WTRUs 102a, 102b, 102c may be connected to local data networks (DNs) 185a, 185b via the UPF 184a, 184b via an N3 interface to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0075] Given that Figures 1A to 1D as well as Figures 1A to 1D Corresponding to the description of the present invention, one or more or all of the functions described herein with reference to any of the following may be performed by one or more simulation elements / devices (not shown): WTRU102a-102d, base station 114a-114b, evolved Node B 160a-160c, MME 162, SGW 164, PGW 166, gNB 180a-180c, AMF 182a-182b, UPF 184a-184b, SMF 183a-183b, DN 185a-185b and / or any other element / device described herein. The simulation device may be one or more devices configured to mimic one or more or all of the functions described herein. For example, the simulation device may be used to test other devices and / or simulate network and / or WTRU functions.

[0076] The simulation device may be designed to implement one or more tests of other devices in a laboratory environment and / or an operator network environment. For example, the one or more simulation devices may perform 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 simulation devices may perform one or more functions or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The simulation device may be directly coupled to another device for testing purposes and / or may use over-the-air wireless communications to perform testing.

[0077] The one or more simulation devices may perform one or more (including all) functions without being implemented / deployed as part of a wired and / or wireless communication network. For example, the simulation device may be used in a test scenario in a test lab and / or a non-deployed (e.g., testing) wired and / or wireless communication network to implement testing of one or more components. The one or more simulation devices may be test equipment. Direct RF coupling and / or wireless communication performed via an RF circuit system (e.g., which may include one or more antennas) may be used by the simulation device to transmit and / or receive data.

[0078] Figure 2 is a block diagram illustrating an example of a communication system 100 including sidelink relays 201. Each sidelink relay 201 may be configured with and may implement relay functionality to support connections and / or traffic relaying between any of: (i) a network and a WTRU 203, (ii) a network and another sidelink relay 201, (iii) two other sidelink relays 201, (iv) another sidelink relay 201 and a WTRU 203, and (v) between two WTRUs 203. Each WTRU 203 may be, for example, WTRU 102 ( FIG. 1 ), which may be out of coverage of the RAN 113 and unable to communicate directly with the core network 115 or may be within coverage and communicate using a device-to-device (D2D) link (e.g., a sidelink). For ease of description, the term "remote WTRU" may be used herein to refer to a WTRU (eg, WTRU 203) that may be indirectly coupled to a network via a sidelink relay (eg, sidelink relay 201).

[0079] Each sidelink relay 201 may be a WTRU 102 ( FIG. 1 ) in which a relay function that supports connection and / or traffic relaying is active (and it is assumed that the WTRU 102 ( FIG. 1 ) is configured with such function). Although not shown, the sidelink relay 201 may provide connection and / or traffic relaying to more than one remote WTRU.

[0080] For simplicity of illustration, it is assumed that the sidelink relay 201 and the remote WTRU 203 are configured according to one or more protocols of Proximity Services (ProSe). ProSe is a service that may be provided by a communication system based on multiple WTRUs being in proximity to each other. The terms "sidelink relay", "relay WTRU", "WTRU-to-network relay", "UE-to-network relay", "WTRU-to-WTRU relay", "UE-to-UE relay", "ProSe L2 relay", "L3 relay", and "WTRU-based relay" may be used interchangeably.

[0081] introduction

[0082] In accordance with the approved study item on NR Sidelink Relay in the 3rd Generation Partnership Project (3GPP) Release 17 documented by Technical Document (“Tdoc”) RP-193253, the Technical Specification Group (TSG) of the RAN (“TSG RAN”) will study the use of UE-to-network relay and UE-to-UE relay based on PC5 (Sidelink). Tdoc RP-193253 states:

[0083] For Release 16, the first version of NR sidelink has been developed and it focuses only on supporting V2X related road safety services. The design aims to support broadcast, multicast and unicast communications in both out-of-coverage scenarios and in-coverage scenarios. In addition, considering a wider range of applications and services, the relay function based on the sidelink should be additionally studied to achieve sidelink / network coverage extension and power efficiency improvement.

[0084] In order to further explore the coverage extension of sidelink-based communications,

[0085] -UE to network coverage extension: Uu coverage reachability is required for a UE to reach a server in a PDN network or a corresponding UE outside the neighborhood. However, for both NG-RAN and NR-based sidelink communications, Release 13 solutions for UE to network relay are limited to EUTRA-based technologies and therefore cannot be applied to NR-based systems.

[0086] -UE-to-UE coverage extension: Proximity reachability is currently limited to single-hop sidelink via EUTRA-based or NR-based sidelink technologies. However, this is not enough without Uu coverage, given the limited single-hop sidelink coverage.

[0087] In summary, sidelink connections should be further extended in the NR framework to support enhanced QoS requirements.

[0088] Under the subheading "4.1 Objectives of SI or Core WI or Test WI", Tdoc RP-193253 states:

[0089] The goal of this research project is to study relay based on single-hop NR sidelink.

[0090] 1. Study mechanisms with minimal regulatory impact to support SA requirements for UE-to-network and UE-to-UE relay over sidelink, focusing on the following aspects for Layer 3 relay and Layer 2 relay [RAN2], as applicable;

[0091] A. Relay (re)selection criteria and process;

[0092] B. Relay / remote UE authorization;

[0093] C. QoS for relay functionality;

[0094] D. Service continuity;

[0095] E. Security of the relay connection after SA3 has provided its conclusion;

[0096] F. Impact on the user plane protocol stack and control plane processes (e.g., connection management of relay connections);

[0097] 2. Study mechanisms to support upper layer operation of discovery model / procedures for sidelink relay assuming no new physical layer channels / signals [RAN2]; ….

[0098] Conventional ProSe UE to network relay relay selection / reselection is performed based on a combination of access stratum (AS) layer quality measurements (e.g., reference signal received power (RSRP) measurements) and upper layer criteria. "3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); General Description; Stage 2", 3GPP Technical Specification (TS) 36.300 v15.4.0 (2018-12), states:

[0099] The eNB controls whether the UE can act as a ProSe UE to network relay:

[0100] - If the eNB broadcasts any information associated with the ProSe UE to network relay operation, the ProSe UE to network relay operation is supported in the cell;

[0101] -eNB can provide:

[0102] - Use the transmission resources of broadcast signaling in RRC_IDLE state and dedicated signaling in RRC_CONNECTED state for ProSe UE to network relay discovery;

[0103] -Use reception resources of broadcast signaling for ProSe UE to network relay discovery;

[0104] - the eNB may broadcast minimum and / or maximum Uu link quality (RSRP) thresholds that the ProSe UE to network relay needs to comply with before it can initiate the UE to network relay discovery procedure. In RRC_IDLE, when the eNB broadcasts the transmission resource pool, the UE uses the thresholds to autonomously start or stop the UE to network relay discovery procedure. In RRC_CONNECTED, the UE uses the thresholds to determine whether it can indicate to the eNB that it is a relay UE and wishes to start ProSe UE to network relay discovery;

[0105] - If the eNB does not broadcast the transmission resource pool for ProSe-UE to network relay discovery, the UE may initiate a request for ProSe-UE to network relay discovery resources taking into account these broadcast thresholds through dedicated signaling.

[0106] - If ProSe-UE to network relay is initiated by broadcast signaling, ProSe UE to network relay discovery can be performed when in RRC_IDLE. If ProSe UE to network relay is initiated by dedicated signaling, relay discovery can be performed as long as it is in RRC_CONNECTED.

[0107] A ProSe UE to network relay that performs sidelink communication for ProSe UE to network relay operation must be in RRC_CONNECTED. After receiving a Layer 2 Link Establishment Request or TMGI Monitoring Request (upper layer message) as specified in TS 23.303

[62] from a remote UE, the ProSe UE to network relay indicates to the eNB that it is a ProSe UE to network relay and intends to perform ProSe UE to network relay sidelink communication. The eNB may provide resources for ProSe UE to network relay communication.

[0108] The remote UE may decide when to start monitoring for ProSe UE to network relay discovery. Depending on the configuration of resources for ProSe UE to network relay discovery, the remote UE may transmit a ProSe UE to network relay discovery request message when in RRC_IDLE or in RRC_CONNECTED. The eNB may broadcast a threshold value, which the remote UE uses to determine whether it may transmit a ProSe UE to network relay discovery request message to connect or communicate with a ProSe UE to network relay UE. The RRC_CONNECTED remote UE uses the broadcasted threshold value to determine whether it may indicate to the eNB that it is a remote UE and wishes to participate in ProSe UE to network relay discovery and / or communication. The eNB may provide transmission resources using broadcast or dedicated signaling, and use broadcast signaling to provide reception resources for ProSe UE to network relay operation. When the RSRP exceeds the broadcast threshold value, the remote UE stops using the ProSe UE to network relay discovery and communication resources.

[0109] NOTE: The exact time of traffic switching from Uu to PC5 or from PC5 to Uu is not known to higher layers.

[0110] The remote UE performs radio measurements at the PC5 interface and uses them together with higher layer criteria as specified in TS 23.303

[62] for ProSe UE-to-network relay selection and reselection. If the PC5 link quality exceeds a configured threshold (pre-configured or provided by the eNB), the ProSe UE-to-network relay is considered suitable in terms of radio criteria. The remote UE selects the ProSe UE-to-network relay that meets the higher layer criteria and has the best PC5 link quality among all suitable ProSe UE-to-network relays.

[0111] The remote UE triggers ProSe UE to network relay reselection when the following conditions occur:

[0112] -The current PC5 signal strength from the ProSe UE to the network relay is lower than the configured signal strength threshold;

[0113] - It receives a Layer 2 Link Release message (upper layer message) as specified in TS 23.303

[62] from the ProSe UE to the network relay.

[0114] In Release 14, studies on UE-to-network relay for business use cases tailored for wearables and IoT devices were performed by TSG RAN. While such studies did not result in the promulgation of any technical specifications, a technical report (TR) provided some preferred solutions for such relays. The TR indicated that UE-to-network relay for wearables and IoT devices is expected to use a layer 2 (L2) relay approach (this is different from ProSe UE-to-network relay, which uses a layer 3 (L3) (e.g., IP layer) relay approach).

[0115] The relay solution in the previous release of the 3GPP LTE specification is based on a one-to-one communication link established at the upper layer (ProSe layer) between two UEs (i.e., the remote UE and the UE-to-network relay). Such a connection is transparent to the AS layer, and the connection management signaling and procedures performed at the upper layer are carried by the AS layer data channel. Therefore, the AS layer is not aware of such a one-to-one connection.

[0116] In NR V2X (Release 16), the AS layer supports the concept of a unicast link between two UEs. Such a unicast link is initiated by upper layers (as in a ProSe one-to-one connection). However, the AS is informed of the existence of such a unicast link, as well as any data transmitted between the two UEs in a unicast manner. With such knowledge, the AS layer can support HARQ feedback, CQI feedback, and power control schemes (which are specific to unicast).

[0117] Unicast links at the AS layer are supported via PC5-RRC connections. In the draft of "3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NR; Radio Resource Control (RRC) Protocol Specification (Release 16)", PC5-RRC connections are defined as follows:

[0118] "A PC5-RRC connection is a logical connection between a source Layer-2ID and a destination Layer-2ID pair in an AS. One PC5-RRC connection corresponds to one PC5 unicast link [xx]. PC5-RRC signaling as specified in subclause 5.X.9 may be initiated after its corresponding PC5 unicast link is established [xx]. When the PC5 unicast link is released as indicated by upper layers, the PC5-RRC connection and the corresponding sidelink SRB and sidelink DRB are released.

[0119] For each PC5-RRC connection for unicast, one Sidelink SRB is used to transport PC5-S messages before PC5-S security has been established. One Sidelink SRB is used to transport PC5-S messages to establish PC5-S security. One Sidelink SRB is used to transport PC5-S messages after PC5-S security has been established, which are protected. One Sidelink SRB is used to transport PC5-RRC signaling, which is protected and sent only after PC5-S security has been established."

[0120] PC5-RRC signaling includes a sidelink (re) configuration message (RRCReconfigurationSidelink), in which the first UE of the two UEs configures the RX related parameters of each sidelink radio bearer (SLRB) in the second UE. Such a (re) configuration message can configure the parameters of each protocol in the RAN L2 stack (SDAP, PDCP, etc.). The second UE can confirm or reject such a (re) configuration, depending on whether it can support the (re) configuration proposed by the first UE.

[0121] In the LTE sidelink, UE-to-network relay is supported. If the RSRP measurement value of the discovery message measured by the remote UE is within the configured range, the UE can act as a UE-to-network relay. A dedicated discovery resource pool is configured for UE-to-network relay and remote UE to support the relay selection process. Specifically, the remote UE performs RSRP measurements of the discovery messages in the dedicated discovery resources during the relay selection process. If there are multiple UE-to-network relays to select from, the remote WTRU shall select the UE-to-network relay with the highest PC5 RSRP.

[0122] In NR V2X (Release 16), the unicast link establishment process is supported. However, the process is handled in the upper layers. When the link establishment is completed, the AS layer is informed of the existence of such unicast links according to the source and destination IDs of each unicast link. Data can then be transmitted between peer UEs in a unicast manner.

[0123] In the NR relay study item, it is expected to study the following: (i) support of UE-to-UE and UE-to-network relay; (ii) support of service continuity; and (iii) use of existing channels (i.e., no discovery channel).

[0124] It is expected that control and / or data channels (e.g., Physical Sidelink Control Channel (PSCCH) and / or Physical Downlink Shared Channel (PDSCH)) will be used for relay discovery. Therefore, resource pool selection, QoS determination, and sidelink measurements for discovery messages need to be addressed.

[0125] For unicast links between UEs via sidelinks, UE-to-UE relaying should ensure service continuity and avoid service interruption. Relying solely on upper layers to perform relay (re)selection for UE-to-UE relaying does not take into account AS layer link quality and may result in service interruption. The rules used for relay determination and / or relay selection (similar to the rules used for UE-to-network relaying) cannot be reused for UE-to-UE relaying because in this case both the source and destination UEs are moving, and whether a UE is allowed to become a relay depends on which source and / or destination UEs it will become a relay for. Issues to be addressed by the various disclosed embodiments also include how the AS layer and / or other layers should participate in relay (re)selection for sidelink relaying (including sidelink to sidelink relay scenario requirements).

[0126] Disclosed herein are methods, apparatus, systems, etc. relating to and / or in conjunction with selection and / or reselection of relays and paths. Such methods, apparatus, systems, etc. may, for example, address the involvement of the AS layer and / or other layers (methods and techniques configured, implemented, and / or performed by these layers) in the selection and / or reselection of sidelink relays and paths (including WTRU to WTRU relay scenarios).

[0127] For simplicity of explanation, the following disclosure is mostly from the perspective of a WTRU (source or destination). One of ordinary skill in the art will recognize that much of such disclosure is equally applicable to sidelink relays and / or network elements (e.g., base stations or other RAN elements), and such modifications and variations are intended to fall within the scope of the present disclosure and the appended claims.

[0128] In various embodiments, a method may be implemented in a first WTRU (e.g., a source WTRU) and may include any of the following: determining one or more first measurements based on one or more first sidelink transmissions received from a second WTRU (e.g., a sidelink relay); receiving from the second WTRU one or more second measurements associated with a path between the first WTRU and a third WTRU (e.g., a destination WTRU) and including the second WTRU, wherein the second measurements may be based at least in part on one or more second sidelink transmissions exchanged between the third WTRU and the second WTRU or between the third WTRU and a fourth WTRU (e.g., another sidelink relay); determining a measurement of the path (“path measurement”) based on at least one of the first measurements and at least one of the second measurements; determining one or more transmission parameters for transmitting one or more discovery messages during a communication period based on any of the path measurements and a quality of service (QoS) criterion; and transmitting the discovery message in accordance with the transmission parameters. The terms “measurement of the path,” “path measurement,” and “combined sidelink measurement” may be used interchangeably herein.

[0129] In various embodiments, the method may include, for example, making a determination to transmit the discovery message based on any one of a QoS criterion and a path measurement value before determining the transmission parameters. In various embodiments, the method may be modified to include, for example, making a determination not to transmit the discovery message based on any one of a QoS criterion and a path measurement value before determining the transmission parameters, and forgoing determining the one or more transmission parameters and transmitting the discovery message according to the transmission parameters.

[0130] In various embodiments, the transmission parameters may include any of: transmission power, number of (re)transmissions, and periodicity for transmission of discovery messages.

[0131] In various embodiments, the method may include triggering transmission of a discovery message based on QoS and path measurements.

[0132] In various embodiments, determining the path measurement value may include determining the path measurement value as a function (metric) of at least one of (i) the first measurement value or (ii) the second measurement value or (iii) the first measurement value and at least one of the second measurement value. In various embodiments, the function may be any one of the minimum RSRP and the maximum RSRP.

[0133] In various embodiments, the path measurement value may include one or more metrics of (i) the first measurement value or (ii) the second measurement value or (iii) at least one of the first measurement value and at least one of the second measurement value. In various embodiments, these metrics may include any of the minimum RSRP and the maximum RSRP.

[0134] In various embodiments, the second measurement value may include any of the following: a channel quality indicator (CQI), a reference signal received power (RSRP), a reference signal received quality (RSRQ), a path gain, a path loss, a distance between the first WTRU and the second WTRU, a distance between the second WTRU and the third WTRU, a reachability indicator, a channel busy rate (CBR) of the resource pool, and a channel occupancy rate (CR) of the second WTRU. In various embodiments, the first measurement value may include any of the following: a channel quality indicator (CQI), a reference signal received power (RSRP), a reference signal received quality (RSRQ), a path gain, a path loss, a distance between the first WTRU and the second WTRU, a channel busy rate (CBR) of the resource pool, and a channel occupancy rate (CR) of the first sidelink relay.

[0135] In various embodiments, the second measurement value may be based at least in part on (further based on) one or more third sidelink transmissions transmitted by the first WTRU. In various embodiments, the second measurement value may be based at least in part on (further based on) one or more fourth sidelink transmissions exchanged between the second WTRU and the fourth WTRU. In various embodiments, the second measurement value may be based at least in part on (further based on) one or more fourth sidelink transmissions exchanged between the fifth WTRU and the fourth WTRU and one or more fifth sidelink transmissions exchanged between the second WTRU and the fifth WTRU.

[0136] In various embodiments, a path between a first WTRU and a third WTRU and including a second WTRU may be a first path, and the method may include receiving a sixth sidelink transmission including a discovery message from a sixth WTRU, wherein the discovery message may include one or more third measurement values ​​associated with a second path between the first WTRU and the third WTRU and including the sixth WTRU, wherein the third measurement values ​​may be based at least in part on one or more seventh sidelink transmissions exchanged between the third WTRU and the sixth WTRU; determining one or more fourth measurement values ​​based on the sixth sidelink transmission; determining a path measurement value of the second path based on at least one of the third measurement values ​​and at least one of the fourth measurement values; and performing selection of the sixth WTRU based at least in part on the path measurement value of the second path.

[0137] In various embodiments, performing selection of the sixth WTRU may include performing selection of the sixth WTRU based at least in part on the path measurement value of the second path and one or more criteria. In various embodiments, the one or more criteria include any of: (i) a received signal strength of the message; (ii) a distance between the first WTRU and the second WTRU; (iii) a distance between the first WTRU and the third WTRU; (iv) a QoS criterion; (v) a location of the first WTRU; (vi) a location of the second WTRU; (vii) a location of the third WTRU; (viii) a CBR of a resource pool; (ix) a CR of the first WTRU; (x) a speed of the second WTRU; (xi) a speed of the third WTRU; (xii) a number of relay links; (xiii) a number of SLRBs currently established at the second WTRU; and (xiv) previous receipt of other relevant messages associated with the reselection event.

[0138] In various embodiments, receiving the second measurement value associated with the first path may include receiving information indicating one or more metrics of one or more of the second measurement values ​​associated with the first path, and determining the path measurement value of the first path may include determining the path measurement value of the first path based on the one or more metrics of the first measurement value and the second measurement value and / or one or more of the second measurement values. In various embodiments, the metrics may include any of a minimum RSRP and a maximum RSRP.

[0139] In various embodiments, the method may be implemented in a first WTRU (e.g., a sidelink relay) and may include any of the following: receiving one or more first measurement values ​​associated with a path between a second WTRU (e.g., a source (destination) WTRU) and a third WTRU (e.g., a destination (source) WTRU) and including the first WTRU, wherein the first measurement values ​​are based at least in part on at least one of: (i) one or more first sidelink transmissions received from the second WTRU, (ii) one or more second sidelink transmissions transmitted from the first WTRU to the third WTRU or to a fourth WTRU (e.g., another sidelink relay), and (iii) a path between the third WTRU and the fourth WTRU or between the third WTRU and the fifth WTRU. one or more third sidelink transmissions exchanged between a third WTRU and a fourth WTRU (another sidelink relay); determining one or more second measurement values ​​based on one or more fourth sidelink transmissions received from the third WTRU or a fourth WTRU; determining a trigger for reporting of one or more of the first measurement values ​​and the second measurement values ​​based on (i) QoS (e.g., of the relay service), (ii) a channel busy rate (CBR) of a resource pool (e.g., configured for sidelink transmissions), and (iii) one or more metrics of the one or more first measurement values ​​or the one or more second measurement values ​​or at least one of the one or more first measurement values ​​and at least one of the one or more second measurement values; and transmitting one or more of the first measurement values ​​and the second measurement values ​​to a second WTRU.

[0140] In various embodiments, transmitting one or more of the first measurement value and the second measurement value to the second WTRU may include transmitting one or more sidelink transmissions to the second WTRU, wherein the sidelink transmissions may include one or more of the first measurement value and the second measurement value.

[0141] In various embodiments, the method may include receiving information indicating that a direct communication message from a second WTRU is imminent. In various embodiments, the information may be sidelink control information (SCI) associated with the direct communication message or may be received in the SCI. In various embodiments, the direct communication message may include a relay request.

[0142] In various embodiments, the method may be implemented in a first WTRU (e.g., a source (or destination) WTRU) and may include any of the following: obtaining one or more measurement values ​​of each of one or more other WTRUs (e.g., sidelink relays), wherein the one or more measurement values ​​of each of the other WTRUs are based at least in part on one or more sidelink transmissions exchanged between the first WTRU and the corresponding other WTRUs; and performing reselection between the one or more other WTRUs based at least in part on the one or more measurement values ​​of the one or more other WTRUs.

[0143] In various embodiments, performing reselection among other WTRUs may include performing reselection among other WTRUs based at least in part on the measured values ​​and the quality of service (QoS) of the service. In various embodiments, performing reselection among other WTRUs may include performing reselection among other WTRUs based at least in part on the one or more measured values ​​and the number of hops per path of one or more of the plurality of paths associated with the one or more other WTRUs. In various embodiments, performing reselection among other WTRUs may include performing reselection among other WTRUs based at least in part on any of the one or more measured values ​​and the QoS criteria (e.g., of the service) and the number of hops per path of one or more of the plurality of paths associated with the one or more other WTRUs. In various embodiments, performing reselection among other WTRUs may include performing reselection among other WTRUs based at least in part on the one or more measured values ​​and the load information of any of the other WTRUs and the first WTRU. In various embodiments, performing reselection among other WTRUs may include performing reselection among other WTRUs based at least in part on the one or more measured values ​​and the load information of any of the other WTRUs, the first WTRU, and the network element.

[0144] In various embodiments, obtaining the measurement values ​​may include determining at least some of the one or more measurement values. In various embodiments, determining the one or more measurement values ​​may include determining a measurement value for each of a plurality of paths associated with the one or more other WTRUs. In various embodiments, determining the measurement value for each of the plurality of paths may include determining the measurement value for each of the plurality of paths based on one or more measurement values ​​of one or more sidelink transmissions occurring over some or all hops of such paths.

[0145] In various embodiments, the measurement value of at least one of the multiple paths may be any of: a sidelink reference signal received power ("SL-RSRP") measurement value of a hop segment of the at least one of the multiple paths and an accumulated SL-RSRP of the hop segments of the at least one of the multiple paths. In various embodiments, the measurement value of at least one of the multiple paths is a combination of SL-RSRP measurement values ​​of multiple hop segments of the at least one of the multiple paths. In various embodiments, the measurement value of at least one hop segment of at least one of the multiple paths may include any of: a measurement value of a sidelink transmission received by the WTRU, an accumulation or other combination of measurement values ​​of sidelink transmissions received by the WTRU, one or more reported measurement values ​​of a transmission, and a reported accumulation or other combination of measurement values ​​of sidelink transmissions.

[0146] In various embodiments, the method may include determining a measurement value for at least one hop of at least one of the plurality of paths. In various embodiments, determining the one or more measurement values ​​may include determining a measurement value for one or more sidelink transmissions occurring on at least one hop of at least one of the plurality of paths. In various embodiments, determining the measurement value for at least one hop of at least one of the plurality of paths includes determining the measurement value using any of and / or as a function of any of: a measurement value of a sidelink transmission received by the WTRU, an accumulated or other combined measurement value of the sidelink transmission received by the WTRU, a reported measurement value of the sidelink transmission, and a reported accumulated or other combination of the measurement values ​​of the sidelink transmission. In various embodiments, determining the measurement value for at least one hop of at least one of the plurality of paths may include determining the measurement value using any of and / or as a function of any of: a measurement value of a sidelink data transmission and a measurement value of a direct communication message transmission. In various embodiments, determining a measurement value for at least one hop of at least one of the multiple paths may include determining the measurement value using any of and / or as a function of any of: a measurement value of a sidelink data transmission and a measurement value of a sidelink discovery message transmission.

[0147] In various embodiments, a method may be implemented in a first WTRU (e.g., a sidelink relay) and may include any of the following: receiving a first sidelink transmission including a message from a second WTRU (e.g., a source WTRU, a destination WTRU, or another sidelink relay); determining a measurement value of the first sidelink transmission; determining to forward the message based on one or more criteria (including the measurement value of the first sidelink transmission); and transmitting a second sidelink transmission including the message and the measurement value of the first sidelink transmission. In various embodiments, the message may be a direct communication message. In various embodiments, the criteria may include any of the following: (i) the received signal strength of the message; (ii) the distance between the first WTRU and the second WTRU; (iii) the distance between the first WTRU and the third WTRU; (iv) QoS criteria; (v) the location of the first WTRU; (vi) the location of the second WTRU; (vii) the location of the third WTRU; (viii) the CBR of the resource pool; (ix) the CR of the first WTRU; (x) the speed of the second WTRU; (xi) the speed of the third WTRU; (xii) the number of relay links; (xiii) the number of SLRBs currently established at the second WTRU; and (xiv) previous reception of other relevant messages associated with the reselection event.

[0148] In various embodiments, a method may be implemented in a first WTRU (e.g., a source (or destination) WTRU) and may include any of the following: receiving a first sidelink transmission including a discovery message from a second WTRU (e.g., a sidelink relay), wherein the discovery message may include one or more first measurement values ​​associated with a path between the first WTRU and a third WTRU and including the second WTRU, wherein the first measurement values ​​may be based at least in part on one or more second sidelink transmissions exchanged between the third WTRU and the second WTRU; determining one or more second measurement values ​​based on the first sidelink transmission; determining a path measurement value for the path based on at least one of the first measurement values ​​and at least one of the second measurement values; and performing selection of the second WTRU based at least in part on the path measurement value for the second path. In various embodiments, performing selection of the second WTRU includes performing selection of the second WTRU based at least in part on the path measurement value for the path and one or more criteria. In various embodiments, the criteria may include any of the following: (i) the received signal strength of the message; (ii) the distance between the first WTRU and the second WTRU; (iii) the distance between the first WTRU and the third WTRU; (iv) QoS criteria; (v) the location of the first WTRU; (vi) the location of the second WTRU; (vii) the location of the third WTRU; (viii) the CBR of the resource pool; (ix) the CR of the first WTRU; (x) the speed of the second WTRU; (xi) the speed of the third WTRU; (xii) the number of relay links; (xiii) the number of SLRBs currently established at the second WTRU; and (xiv) previous reception of other relevant messages associated with the reselection event.

[0149] In various embodiments, methods for performing and / or used in conjunction with relay selection or reselection ("(re)selection") may be implemented in a first WTRU. Such methods include methods that may include any of: receiving from one or more sidelink relays one or more sidelink measurement values ​​associated with a path defining a plurality of hops, the plurality of hops including (i) a first hop between a first WTRU and a first of the one or more sidelink relays and (ii) a second hop between the first or second of the one or more sidelink relays and a second WTRU or network element; and if the one or more sidelink measurement values ​​satisfy a QoS-related condition: triggering selection or reselection of the first sidelink relay; and / or causing selection or reselection of the second sidelink relay.

[0150] In various embodiments, causing selection or reselection of the second sidelink relay may include transmitting one or more messages to one or more of: the first sidelink relay, the second WTRU, and any sidelink relay within a hop segment of the second sidelink relay, wherein the one or more messages indicate selection or reselection to the second sidelink relay.

[0151] In various embodiments, triggering selection or reselection of the first sidelink relay may include any of: determining one or more transmission period (TP) resources for transmission during one or more TPs within an upcoming communication cycle; and using the one or more TP resources to transmit any of a direct communication message and a retransmission of a direct communication message during the one or more TPs.

[0152] In various embodiments, the method may include determining the one or more TPs within an upcoming communication period.

[0153] In various embodiments, the method may include indicating in sidelink control information (SCI) that the direct communication message includes a relay request.

[0154] In various embodiments, the direct communication message may include a relay request and / or may be a relay request message.

[0155] In various embodiments, determining one or more TP resources may include determining a pattern of the one or more TP resources to use for transmissions during the one or more TPs in an upcoming communication cycle.

[0156] In various embodiments, determining one or more TP resources may include determining the one or more TP resources and a periodicity of the one or more TP resources for transmission during the one or more TPs in an upcoming communication cycle.

[0157] In various embodiments, transmitting any of a direct communication message and a retransmission of a direct communication message using the one or more TP resources may include transmitting any of a direct communication message and a retransmission of a direct communication message using the one or more TP resources during any TP of the one or more TPs.

[0158] In various embodiments, determining one or more TP resources for transmission during one or more TPs may include determining the one or more TP resources based on any of the one or more sidelink measurement values, a quality of service (QoS) of the service, and a number of hops of a current relay path.

[0159] In various embodiments, determining the one or more TPs may include determining the one or more TPs based on any of the one or more sidelink measurements, a quality of service (QoS) of a service, and a number of hops of a current relay path.

[0160] In various embodiments, determining one or more TP resources and a periodicity of the one or more TP resources for transmission during multiple TPs is based on any of the one or more sidelink measurements, QoS of service, and a number of hops of a current relay path.

[0161] In various embodiments, the one or more sidelink measurements may include a first sidelink measurement associated with the first hop segment and a second sidelink measurement associated with the second hop segment, respectively. In various embodiments, the one or more sidelink measurements may include a first sidelink measurement associated with the first hop segment. In various embodiments, the one or more sidelink measurements may include a second sidelink measurement associated with the second hop segment.

[0162] In various embodiments, the second sidelink measurement value may include any of: a channel quality indicator (CQI), a reference signal received power (RSRP), a reference signal received quality (RSRQ), a path gain, a path loss, a distance between the first sidelink relay or the second sidelink relay and the second WTRU, a reachability indicator (e.g., whether the second WTRU is reachable or unreachable), a channel busy rate (CBR) of a resource pool configured for sidelink transmission, and a channel occupancy rate (CR) of the first sidelink relay or the second sidelink relay.

[0163] In various embodiments, the first sidelink measurement value may include any of the following: CQI, RSRP, RSRQ, path gain, path loss, the distance between the first sidelink relay and the first WTRU, the CBR of the resource pool configured for sidelink transmission, and the CR of the first sidelink relay.

[0164] In various embodiments, the first sidelink measurement value and the second sidelink measurement value may be different types of sidelink measurements. In various embodiments, the communication period may be a maximum communication request time.

[0165] In various embodiments, the one or more TP resources used for transmission during one or more TPs may include at least one TP resource to be used during a single TP, and determining the one or more TP resources may include selecting at least one TP resource to be used during the single TP based on a resource selection window. In various embodiments, the resource selection window begins at a first time n and ends at a second time n+T. In various embodiments, the first time n corresponds to when selection or reselection of the first sidelink relay is triggered, and wherein T is based on a delay metric.

[0166] In various embodiments, the first WTRU may be a source WTRU and the second WTRU may be a destination WTRU. In various embodiments, the source WTRU may receive RSRP measurements from the sidelink relay for a first hop between the source WTRU and the sidelink relay and a second hop between the sidelink relay and the destination WTRU. In various embodiments, the source WTRU may trigger relay (re)selection if the combined RSRP measurements satisfy a QoS-related condition (e.g., based on a minimum of two RSRP measurements).

[0167] In various embodiments, methods for performing and / or used in conjunction with relay selection or reselection ("(re)selection") may be implemented in a sidelink relay. Such methods include methods that may include any of: receiving one or more sidelink measurements associated with a path defining a plurality of hops, the plurality of hops including (i) a first hop between a first wireless transmit receive unit (WTRU) and a first one of one or more sidelink relays and (ii) a second hop between the first or second one of the one or more sidelink relays and a second WTRU or network element; and transmitting the one or more sidelink measurements to the first WTRU.

[0168] In various embodiments, transmitting the one or more sidelink measurements to the first WTRU may include transmitting the one or more sidelink measurements to the first WTRU via a direct link between a sidelink relay and the first WTRU.

[0169] In various embodiments, the sidelink relay may be a first sidelink relay. In various embodiments, the sidelink relay may be a second sidelink relay.

[0170] In various embodiments, the method may include receiving information (e.g., signaling and / or signaling including information) indicating that a direct communication message from a first WTRU is imminent. In various embodiments, the information may be sidelink control information (SCI) associated with the direct communication message or may be received in the SCI.

[0171] In various embodiments, the method may include obtaining one or more sidelink measurements associated with the first hop segment in conjunction with receiving a direct communication message from the first WTRU. In various embodiments, obtaining the one or more sidelink measurements may include measuring the one or more sidelink measurements associated with the first hop segment in conjunction with receiving a direct communication message from the first WTRU. In various embodiments, obtaining the one or more sidelink measurements may include receiving the one or more sidelink measurements associated with the first hop segment from a first sidelink relay.

[0172] In various embodiments, the method may include adjusting the direct communication message to include or indicate the one or more sidelink measurement values ​​associated with the first hop.

[0173] In various embodiments, the method may include transmitting the adjusted direct communication message to or toward the second WTRU.

[0174] In various embodiments, the direct communication message may include a relay request and / or may be a relay request message.

[0175] In various embodiments, the first sidelink relay may receive RSRP measurements in the second hop (eg, from the destination WTRU) and forward the RSRP measurements to the first WTRU (eg, for relay reselection triggering).

[0176] In various implementations, the first sidelink relay may begin measuring RSRP after receipt of an SCI indicating a relay request message (eg, for relay selection).

[0177] In various embodiments, the first sidelink relay may include the RSRP measurement value of the first hop in the relay request message and may forward it to the destination WTRU.

[0178] In various embodiments, a method for performing and / or using in conjunction with path selection or reselection ("(re)selection") may be implemented in a first WTRU and may include any of the following: receiving one or more sidelink measurement values ​​associated with each of a plurality of paths from one or more sidelink relays, wherein each path defines a plurality of hops, including (i) a first hop between the first WTRU and a first of the one or more sidelink relays and (ii) a second hop between the first or second of the one or more sidelink relays and a second WTRU or network element; and performing path selection among the plurality of paths based at least in part on the one or more sidelink measurement values.

[0179] In various embodiments, performing path selection among the plurality of paths may include performing path selection among the plurality of paths based on the one or more sidelink measurements and a quality of service (QoS) of a service.

[0180] In various embodiments, performing path selection among the plurality of paths may include performing path selection among the plurality of paths based on the one or more sidelink measurements and a number of hops per path of one or more of the plurality of paths.

[0181] In various embodiments, performing path selection among the multiple paths may include performing path selection among the multiple paths based on the one or more sidelink measurements and any of a quality of service (QoS) of the service and a number of hops per path for one or more of the multiple paths.

[0182] In various embodiments, the first WTRU may be a destination WTRU. In various embodiments, the first WTRU may be a source WTRU.

[0183] In various embodiments, performing path selection among the plurality of paths may include performing path selection among the plurality of paths based on sidelink measurements and load information of any of the one or more sidelink relays, the second WTRU, and the network element.

[0184] In various embodiments, the method may include determining a sidelink measurement value. In various embodiments, determining the sidelink measurement value may include determining a sidelink measurement value for each of the plurality of paths. In various embodiments, determining the sidelink measurement value for each of the plurality of paths may include determining the sidelink measurement value for each of the plurality of paths based on one or more sidelink measurement values ​​for some or all hops of such paths.

[0185] In various embodiments, the sidelink measurement value of at least one of the multiple paths may be any of: SL-RSRP measurement values ​​of hops of the at least one of the multiple paths and accumulated SL-RSRP of hops of the at least one of the multiple paths. In various embodiments, the sidelink measurement value of at least one of the multiple paths may be a combination of SL-RSRP measurement values ​​of multiple hops of the at least one of the multiple paths. In various embodiments, the sidelink measurement value of at least one hop of at least one of the multiple paths may include any of: sidelink measurement values ​​of transmissions received by the WTRU, accumulated or other combined sidelink measurement values ​​of transmissions received by the WTRU, reported / forwarded sidelink measurement values ​​of transmissions transmitted by any of a sidelink relay, another WTRU, and a base station, and / or reported / forwarded accumulated or other combination of sidelink measurement values ​​of transmissions transmitted by any of a sidelink relay, another WTRU, and a base station.

[0186] In various embodiments, the method may include determining a sidelink measurement for at least one hop of at least one of the multiple paths. In various embodiments, determining the one or more sidelink measurements may include determining a sidelink measurement for at least one hop of at least one of the multiple paths. In various embodiments, determining the sidelink measurement for at least one hop of at least one of the multiple paths may include determining the sidelink measurement using any of and / or as a function of any of: sidelink measurements of transmissions received by the WTRU, an accumulation or other combination of sidelink measurements of transmissions received by the WTRU, reported / forwarded sidelink measurements of transmissions transmitted by any of a sidelink relay, another WTRU, and a base station, and / or an accumulation or other combination of reported / forwarded sidelink measurements of transmissions transmitted by any of a sidelink relay, another WTRU, and a base station. In various embodiments, determining the sidelink measurement value for at least one hop of at least one of the plurality of paths may include determining the sidelink measurement value using any of and / or as a function of any of: a sidelink measurement value for data transmission and a sidelink measurement value for direct communication message transmission. In various embodiments, determining the sidelink measurement value for at least one hop of at least one of the plurality of paths may include determining the sidelink measurement value using any of and / or as a function of any of: a sidelink measurement value for data transmission and a sidelink measurement value for discovery message transmission.

[0187] In various embodiments, the method may be implemented in a first WTRU (e.g., a source (or destination) WTRU) and may include any of the following: receiving one or more sidelink measurement values ​​associated with each of a plurality of paths from one or more sidelink relays, wherein each path defines a plurality of hops including (i) a first hop between the first WTRU and a first of the one or more sidelink relays and (ii) a second hop between the first or second of the one or more sidelink relays and a second WTRU or network element; and performing (re)selection between the one or more sidelink relays based at least in part on the one or more sidelink measurement values.

[0188] In various embodiments, performing (re)selection among the one or more sidelink relays may include performing (re)selection among the one or more sidelink relays based on the one or more sidelink measurement values ​​and a QoS criterion (e.g., of a service). In various embodiments, performing (re)selection among the one or more sidelink relays may include performing (re)selection among the one or more sidelink relays based on the one or more sidelink measurement values ​​and a number of hops per path of one or more of the plurality of paths.

[0189] In various embodiments, performing (re)selection among the one or more sidelink relays may include performing (re)selection among the one or more sidelink relays based on any of the one or more sidelink measurement values ​​and a QoS criterion (e.g., of a service) and a number of hops per path of one or more of the plurality of paths. In various embodiments, performing (re)selection among the one or more sidelink relays may include performing (re)selection among the one or more sidelink relays based on the one or more sidelink measurement values ​​and load information of any of the one or more sidelink relays, a second WTRU, and a network element.

[0190] In various embodiments, the method may include determining the one or more sidelink measurements. In various embodiments, determining the one or more sidelink measurements may include determining a sidelink measurement for each of the plurality of paths. In various embodiments, determining the sidelink measurement for each of the plurality of paths may include determining the sidelink measurement for each of the plurality of paths based on one or more sidelink measurements for some or all hops of such paths.

[0191] In various embodiments, the sidelink measurement value of at least one of the multiple paths may be any of: SL-RSRP measurement values ​​of hops of the at least one of the multiple paths and accumulated SL-RSRP of hops of the at least one of the multiple paths. In various embodiments, the sidelink measurement value of at least one of the multiple paths may be a combination of SL-RSRP measurement values ​​of multiple hops of the at least one of the multiple paths. In various embodiments, the sidelink measurement value of at least one hop of at least one of the multiple paths may include any of: sidelink measurement values ​​of transmissions received by the WTRU, accumulated or other combined sidelink measurement values ​​of transmissions received by the WTRU, reported / forwarded sidelink measurement values ​​of transmissions transmitted by any of a sidelink relay, another WTRU, and a base station, and / or reported / forwarded accumulated or other combination of sidelink measurement values ​​of transmissions transmitted by any of a sidelink relay, another WTRU, and a base station.

[0192] In various embodiments, the method may include determining a sidelink measurement for at least one hop of at least one of the multiple paths. In various embodiments, determining the one or more sidelink measurements may include determining a sidelink measurement for at least one hop of at least one of the multiple paths. In various embodiments, determining the sidelink measurement for at least one hop of at least one of the multiple paths may include determining the sidelink measurement using any of and / or as a function of any of: sidelink measurements of transmissions received by the WTRU, an accumulation or other combination of sidelink measurements of transmissions received by the WTRU, reported / forwarded sidelink measurements of transmissions transmitted by any of a sidelink relay, another WTRU, and a base station, and / or an accumulation or other combination of reported / forwarded sidelink measurements of transmissions transmitted by any of a sidelink relay, another WTRU, and a base station. In various embodiments, determining the sidelink measurement value for at least one hop of at least one of the plurality of paths may include determining the sidelink measurement value using any of and / or as a function of any of: a sidelink measurement value for data transmission and a sidelink measurement value for direct communication message transmission. In various embodiments, determining the sidelink measurement value for at least one hop of at least one of the plurality of paths may include determining the sidelink measurement value using any of and / or as a function of any of: a sidelink measurement value for data transmission and a sidelink measurement value for discovery message transmission.

[0193] In various embodiments, an apparatus, which may include any of a processor and a memory, is configured to perform a method as in at least one of the preceding embodiments.

[0194] In various embodiments, the apparatus may be configured as and / or configured with an element of a WTRU. In various embodiments, the apparatus may be configured as and / or configured with an element of a sidelink relay. In various embodiments, the apparatus may be configured as and / or configured with an element of a base station or other network (e.g., RAN) element.

[0195] A WTRU may engage in direct communications with: (i) another WTRU via any direct link between the two WTRUs and one or more sidelink relays, or (ii) a network element via one or more sidelink relays. Direct communications may be established at one or more layers of a communication protocol stack, and communications may be considered direct communications if sidelink communications are involved at any of the one or more layers. A WTRU may transmit one or more direct communication messages to one or more WTRUs and / or network elements to (i) cause the one or more WTRUs and / or network elements to engage in one or more direct communications, and / or (ii) change or cause a change in one or more direct communications with the one or more other WTRUs and / or network elements.

[0196] Examples of direct communication messages may include (e.g., upper layer) messages intended for link establishment, discovery messages, combinations of upper layer messages and access layer (AS) layer messages, response messages (e.g., messages sent in response to direct communication messages), data transmissions, etc. An example of a message intended for link establishment may be a PC5 signaling (PC5-S) direct communication request message (or "DIRECT_COMM_REQ" message). A discovery message may be a discovery message triggered and / or sent by an upper layer or AS layer. A combined upper layer and AS layer message may be, for example, an upper layer message encapsulated in an AS layer message, such as a PC5-RRC message with an upper layer container.

[0197] A direct communication message may include various information, such as any of the following: (i) a source identifier (ID); (ii) a destination (ID); (iii) information related to the services provided and the corresponding QoS; (iv) target user information; (v) relay-related information, such as whether the service allows relaying, the number of hops (e.g., the maximum number of hops), and any one of one or more relay IDs; and (vi) authentication information, such as information supporting security protection (e.g., information used to support security protection).

[0198] Representative methods for triggering / performing a relay (re)selection process

[0199] The WTRU (e.g., its AS layer) may receive and / or be informed of a specific message (e.g., a direct communication message) from an upper layer. In one method, the AS layer may receive an indication of the presence of a direct communication message from an upper layer. Alternatively, the WTRU may be (pre-)configured with one or more dedicated logical channels (LCHs) associated with the direct communication message. The WTRU may perform one or more processes described herein upon receipt of a direct communication message.

[0200] The WTRU (eg, its AS layer) may trigger the relay (re)selection process based on one or more events and / or factors. The events and / or factors may, for example, occur at the AS layer and / or be considered by the AS layer. Examples of events and / or factors may include any of the following: (i) detection of a radio link failure (RLF) for a sidelink relay; (ii) determination of whether a measured channel busy rate (CBR) satisfies (e.g., exceeds) a threshold; (iii) determination of whether a measured channel occupancy rate (CR) satisfies (e.g., exceeds) a threshold; (iv) determination of whether a number of HARQ DTXs associated with transmissions to the sidelink relay satisfies (e.g., has reached) a threshold; (v) RSRP and / or CQI measurements reported by the sidelink relay satisfy (e.g., exceed) a threshold; (vi) combined RSRP / CQI measurements within multiple hops (as described herein) satisfy (e.g., exceed) a threshold; (vii) expiration of an inactivity timer (e.g., relay (re)selection may be triggered after expiration of a time period during which the WTRU has not performed any transmissions to and / or receptions from the sidelink relay).

[0201] Other examples of events may include receiving an indication from a peer WTRU and / or sidelink relay of an event that the peer WTRU and / or sidelink relay may have detected relative to a (e.g., next) hop segment (which event may be similar to the above event). For example, the indication may indicate that the peer WTRU and / or sidelink relay has experienced RLF on a link associated with the same relay link and / or path (e.g., next hop segment). Alternatively and / or additionally, the indication may indicate that the peer WTRU and / or sidelink relay received an RSRP measurement value for a link associated with the same relay link and / or path (e.g., next hop segment) that met (e.g., dropped below) a threshold. Alternatively and / or additionally, the indication indicates that a number of consecutive HARQ DTXs on the peer WTRU's transmissions met (e.g., reached) a threshold. Alternatively and / or additionally, the indication indicates that a number of consecutive HARQ DTXs on the sidelink relay's transmissions met (e.g., reached) a threshold.

[0202] Triggering (re)selection may include any of the following. The WTRU (e.g., its AS layer) may inform the upper layer of a trigger (e.g., based on an event and / or factor) that requires relay (re)selection. The WTRU (e.g., its AS layer) may inform the upper layer of a trigger that requires relay (re)selection and expects to receive a direct communication message from the upper layer in response, and receives the direct communication message from the upper layer. The WTRU (e.g., its AS layer) may initiate the transmission of a direct communication message or a related message. The WTRU may transmit a direct communication message.

[0203] When relay (re)selection is triggered (e.g., in conjunction with the WTRU determining to transmit a direct communication message), the WTRU may perform any of the following. The WTRU may take various actions to avoid or limit unnecessary measurements (and therefore, battery usage), including suspending or canceling some or all relay assessment measurements (e.g., measurements used to determine whether to perform relay (re)selection). The WTRU may prioritize the transmission of any subsequent direct communication messages received from upper layers. The WTRU may initiate and / or change the scheduling of various measurements, such as initiating CQI measurements to be performed by a peer WTRU and / or sidelink relay, and / or instructing a peer WTRU and / or sidelink relay to initiate CQI measurements of its own peer WTRU and / or sidelink relay (e.g., next hop segment).

[0204] The WTRU may determine and / or apply a processing behavior for a message (eg, a direct communication message). The processing behavior may include a pre-transmission behavior and / or a transmission behavior.

[0205] A message (e.g., a direct communication message) may be triggered / generated at an upper layer. Pre-transmission behavior may be used to determine (e.g., help the WTRU determine) whether the message is to be generated and / or transmitted and / or whether the message should be generated / transmitted. The pre-transmission behavior may include various actions performed by the WTRU before performing transmission of the message (if any). The various actions may include any of the following actions:

[0206] The AS layer may report various sidelink measurement values ​​to the upper layer, such as the sidelink measurement value of each hop of one or more (e.g., each) hop, the combined sidelink measurement value of multiple hops, and the sidelink measurement value of each hop.

[0207] Measurements, reachability indication to the destination WTRU, etc.

[0208] The AS layer may indicate to the upper layer the necessity of transmitting a message (eg, a direct communication message)

[0209] and / or requiring transmission of the message (eg, a direct communication message); and

[0210] The WTRU may trigger the transmission of a message (e.g., a direct communication message), for example,

[0211] The WTRU may determine whether the message is to be transmitted and / or should be transmitted.

[0212] The transmission behavior may include the transmission of one or more transmission blocks (TBs) associated with the message. The transmission behavior may include any of the following parameters for the transmission of a message (e.g., a direct communication message):

[0213] The priority of the message, which may be indicated in the SCI of the corresponding transmission of the message and / or its

[0214] Can be applied to single or multiple transmission periods (TP);

[0215] The delay of the TB may be applicable to a single or multiple TPs and / or it may be based on a minimum value of a timer (e.g., T2) associated with a resource selection window (e.g., for a single TP) and / or

[0216] or maximum value (e.g., to determine);

[0217] The number of retransmissions, which can apply to a single or multiple TPs;

[0218] The number of subchannels available for one transmission of a message, which may apply to single or multiple TPs;

[0219] Modulation and Coding Scheme (MCS), which may be applicable to a single or multiple TPs;

[0220] Transmit power, which can apply to single or multiple TPs;

[0221] Reference signal (RS) patterns (e.g., demodulation reference signal (DMRS) patterns) for the physical sidelink shared channel (PSSCH), which may be applicable to single or multiple TPs;

[0222] duration of one or more TPs (e.g., the WTRU may determine to transmit a message (e.g., a direct communication message) in multiple transmission periods. The WTRU may determine the duration of one transmission period that may be used to perform a (re)transmission of one TB);

[0223] Maximum communication request time (e.g., the maximum communication request time may be used to determine whether a current unicast session between a source and a destination WTRU may (or should) be maintained. If the source WTRU does not receive a response from the destination WTRU within the maximum communication request time, the source WTRU may stop the transmission session between the WTRUs. Alternatively, if the source WTRU receives a response within the maximum communication request time, the source WTRU may continue the transmission session between the WTRUs);

[0224] A resource pool used for transmission of the message;

[0225] Other transmission parameters applicable to a single TP;

[0226] Other parameters applicable to multiple TPs; and

[0227] Parameters applicable to the communication cycle.

[0228] Figure 3 An exemplary transmission behavior of a direct communication message is shown. The WTRU may trigger resource selection for a direct communication message at time n. The WTRU may determine to perform two transmissions (e.g., an initial transmission and a retransmission) of a direct communication message within a TP (i.e., P). The WTRU may perform resource selection for a first TB from among various resources that fall within a resource selection window before time n+T2. The WTRU may determine a maximum communication request time as n+T. The maximum communication request time may include 3 TPs, each of which may include resources that may be selected for transmission of a direct communication message (e.g., one or more TBs thereof).

[0229] The WTRU may associate a direct communication message with an established link. The link may include and / or define one or more sidelink radio bearers (SLRBs), QoS processes, etc. The WTRU may determine the association based on various information, including any of upper layer information, time since resource reselection was triggered, and LCH association. For example, the WTRU may receive an L2 destination ID with a direct communication message and may associate the direct communication with a unicast link and / or one or more SLRBs configured for the link. As another example, the WTRU may trigger resource reselection for a specific unicast link and / or one or more SLRBs, and may associate a direct communication message received from an upper layer after the trigger (e.g., in advance in time) with such a link. Alternatively and / or additionally, the WTRU may associate an LCH with each unicast link and / or SLRB, and may associate any direct communication message received on the LCH with the link and / or SLRB.

[0230] The WTRU may determine the processing behavior of a message (e.g., a direct communication message) based on various information, including any of the following: the type of message ("message type"), the type of service ("service type"), the types of WTRUs supported, the QoS of the service associated with the message, the number of hops in the current path, the maximum number of hops allowed for the service, the combined sidelink measurement value of the current path, the CBR of the resource pool measured by any WTRU and / or sidelink relay in the current path, the CR of the WTRU and / or sidelink relay, the location of the WTRU and / or sidelink relay (possibly in combination with the location of another WTRU and / or sidelink relay), measurements of the Uu interface ("Uu measurements"), and information from upper layers.

[0231] Message Type

[0232] The WTRU may determine the transmission behavior of a message based on the type of message. For example, the WTRU may determine the transmission parameters of a direct communication message. The WTRU may be (pre-)configured with a set (e.g., a range) of values ​​for each parameter (e.g., priority, delay, periodicity, reliability, etc.) of the transmission behavior for a message type (e.g., a direct communication message). The WTRU may determine which of the values ​​of each parameter to select based on other criteria. For example, the WTRU may be configured with a set of DMRS patterns for a direct communication message and may determine which of the DMRS patterns to select based on the speed of the WTRU.

[0233] Service Types and Supported WTRU Types

[0234] The WTRU may determine a resource pool for selecting resources for transmitting messages associated with the service (e.g., direct communication messages) based on the type of service and / or the supported WTRU types in the service. For example, the WTRU may be (pre-)configured with multiple resource pools, from which resources will be selected for transmitting direct communication messages. The multiple resource pools may include dedicated resource pools and shared resource pools. The shared resource pool may be used for the transmission of data and / or direct communication messages. If the service supports reduced sensing capability WTRUs (e.g., pedestrian UE (PUE)), the WTRU may select a dedicated resource pool for transmitting direct communication messages. If the service only supports communications between full sensing capability WTRUs (e.g., vehicle UE (VUE)), the WTRU may select a shared resource pool for transmitting direct communication messages.

[0235] The QoS of the service associated with the message

[0236] The WTRU may trigger the transmission of a direct communication message to (re)select a path for communicating with other WTRUs. The WTRU may determine the transmission behavior of the direct communication message based on the QoS of the service that the WTRU wishes to (re)establish with one or more other WTRUs. The WTRU may use a first transmission behavior (e.g., a transmission behavior with a high transmission priority, a large number of retransmissions, a low maximum communication request time, a higher transmission power, etc.) for services that require low service interruption time. Alternatively, the WTRU may use a second transmission behavior (e.g., a transmission behavior that may have a lower priority, a smaller number of retransmissions, a higher maximum communication request time, etc. compared to the first transmission behavior) for services that are not sensitive to service interruption.

[0237] Parameters for the first transmission behavior and / or the second transmission behavior may be (pre)configured and / or determined by the WTRU. For example, the WTRU may determine the periodicity, number of TPs, and number of retransmissions applicable to one or more TPs (such as disclosed herein) for the transmission of a direct communication message based on the QoS of the service associated with the direct communication. The WTRU may determine the QoS of the service associated with the message based on whether the direct communication message is to be sent to facilitate and / or achieve continuity of the ongoing service. For example, the WTRU may trigger resource selection when one or more SLRBs associated with relay traffic are configured. The WTRU may determine the transmission behavior for direct communication based on parameters associated with the established SLRBs. For example, the WTRU may be configured with a transmission behavior for direct communication associated with each SLRB configuration. Alternatively, the WTRU may be configured with a transmission behavior for direct communication associated with one or more QoS profiles of one or more QoS flows mapped to the established bearer.

[0238] The current path and / or the number of hops allowed for the service

[0239] The WTRU may determine a transmission behavior for a direct communication message based on the number of hops of an ongoing link (e.g., SLRB) to which the direct communication message is associated (e.g., the direct communication may be associated with a relay reselection of an ongoing link / SLRB) and / or a maximum number of hops allowed for a service / SLRB associated with the direct communication message. For example, the WTRU may use a first transmission behavior when the current or maximum number of hops allowed for the service meets (e.g., is less than) a threshold, and may use a second transmission behavior when the current or maximum number of hops allowed for the service fails to meet (e.g., is greater than) a threshold and / or meets or fails to meet another threshold.

[0240] Combined sidelink measurements for the current path

[0241] The WTRU may determine the transmission behavior of the message based on the combined sidelink measurement value of the current path and / or any sidelink measurement value. For example, when the combined RSRP measurement value of the two hop segments meets a condition (e.g., meets (e.g., is less than) a first threshold), the WTRU may determine the pre-transmission behavior of the direct communication message (e.g., triggering the transmission of the message). When the combined RSRP measurement value of the two hop segments meets (e.g., is less than) a first threshold and / or meets (e.g., is greater than) a second threshold, the WTRU may use the first transmission behavior. For example, when the combined RSRP measurement value of the two hop segments is between the first threshold and the second threshold, the WTRU may use the first transmission behavior. If the combined RSRP measurement value of the two hop segments meets (e.g., is less than) a third threshold and / or one of the hop segments in the path is unreachable, the WTRU may use the second transmission behavior. Parameters for the first transmission behavior and / or the second transmission behavior may be (pre)configured and / or determined by the WTRU.

[0242] The CBR of the resource pool in the current path (e.g., measured by any WTRU) and / or the CBR of the resource pool in the WTRU and / or sidelink Following CR

[0243] The WTRU may determine the pre-transmission behavior of the direct communication message (e.g., whether to trigger the transmission of the direct communication message) based on the CBR of the resource pool and / or the CR of the WTRU and / or the sidelink relay. If the CBR meets (e.g., is less than) a threshold and / or the CR meets (e.g., is less than) a threshold, the WTRU may trigger one or more transmissions of the message.

[0244] The WTRU may determine a transmission behavior for a direct communication message based on a CBR of a resource pool and / or a CR of the WTRU and / or a sidelink relay. If the CBR satisfies (e.g., is less than) a first threshold and / or the CR satisfies (e.g., is less than) a second threshold, the WTRU may use a first transmission behavior. If the CBR fails to meet (e.g., is greater than) a first threshold or meets another threshold and / or the CR fails to meet (e.g., is greater than) a second threshold or meets another threshold, the WTRU may use a second transmission behavior.

[0245] WTRU and / or sidelink relay location and / or Uu measurements

[0246] The WTRU may determine the processing behavior of a message (e.g., a direct communication message) based on the location of the WTRU and / or the sidelink relay and / or one or more Uu measurements between the WTRU and the network. For example, the WTRU may be (pre) configured with a set of zones and / or locations to initiate a direct communication message. If the WTRU belongs to the set of (pre) configured / allowable zones, the WTRU may trigger a direct communication message. The WTRU may determine the set of zones and / or locations for initiating a direct communication message based on information (e.g., location information) received from another WTRU and / or a sidelink relay. For example, a sidelink relay may receive the location of a source WTRU and / or a destination WTRU, and may determine whether to act as a relay for the source WTRU and / or the destination WTRU based on the distance to the source WTRU and / or the destination WTRU. A sidelink relay WTRU may determine whether to transmit / relay a direct communication message based on the distance to the source / destination WTRU. As another example, the WTRU may determine the pre-transmission behavior of a direct communication message based on one or more Uu measurements between the WTRU and the network. If one or more RSRP measurement values ​​of the Uu interface meet (eg, are less than) a threshold, the WTRU may trigger one or more transmissions of direct communication.

[0247] Upper level information

[0248] The WTRU may receive (explicitly or implicitly) information from upper layers that may affect the transmission behavior of direct communication. For example, the WTRU may receive an indicator (e.g., in the form of a value) that the WTRU can use to associate direct communication with a transmission behavior. The indicator may be in the form of a priority, for example. Alternatively, the WTRU may receive a direct communication message on one of a plurality of LCHs and may associate a transmission behavior with each LCH. Alternatively, the WTRU may receive an indication of whether the direct communication is associated with an ongoing service or a new service. The WTRU may determine the transmission behavior based on whether the direct communication is associated with an ongoing service or a new service. The determined transmission behavior for an ongoing service may be different from the determined transmission behavior for a new service. Alternatively, the WTRU may receive an indication of whether to enable "service continuity". The WTRU may determine the transmission behavior based on the presence and / or absence of the indication.

[0249] The WTRU may initiate a timer when it transmits a direct communication message or in conjunction with transmitting a direct communication message. After the timer expires, the WTRU may perform a (re)transmission of the same TB or another TB carrying the direct communication message. The value of the timer may be configured based on various factors, such as those disclosed herein (e.g., the value of the timer may be part of the transmission behavior).

[0250] A WTRU transmitting a direct communication message may be configured with one or more behaviors associated with processing a response message received in response to the direct communication message. Such a response message may be an upper layer message, an AS layer message, or a combination of an upper layer message and an AS layer message.

[0251] The WTRU may be (pre-)configured with a timer used in conjunction with determining the feasibility of a response message. The WTRU may initiate a timer when transmitting a message (e.g., a direct communication message). If the WTRU does not receive a response message corresponding to (e.g., in response to) the message from the destination WTRU before the timer expires, the WTRU may determine that no destination WTRU is reachable. Alternatively, if the WTRU receives a response from the destination WTRU before the timer expires, the WTRU may determine that the process of initiating communication between the source and destination WTRUs is successful and may start a data transmission process between the WTRUs. In various embodiments, the WTRU may perform various actions after successfully receiving one or more response messages from the destination WTRU. The various actions may include any of notifying upper layers and initiating configuration of a bearer on the corresponding path.

[0252] The value of the timer (e.g., an initial value) may be determined based on any of: (i) the QoS of the service; (ii) the availability of a sidelink measurement value (e.g., a combined sidelink measurement value) for a corresponding path (e.g., a current path); (iii) the number of hops in the corresponding path (e.g., the current path); and (iv) the CBR of the resource pool.

[0253] The WTRU may include in the message (e.g., a direct communication message) timing information of an expected response ("expected response timing") and / or information about a delay budget for the message (e.g., a direct communication message) ("delay budget information"). The expected response timing and / or delay budget information may be provided to support / assist a WTRU and / or a sidelink relay receiving a direct communication message in determining processing behavior for the message, including, for example, as a factor in making a decision as to whether to trigger and / or transmit a response message and / or making other transmission decisions.

[0254] The WTRU may initiate a timer and / or counter upon receipt of a direct communication message used in conjunction with processing of sidelink measurement values. The WTRU may increment the counter after each reception of a direct communication message and / or transmission associated with the same source WTRU. The WTRU may perform various actions upon expiration of a timer and / or upon satisfying a threshold value of the counter. The various actions may include any of: reporting sidelink measurement values ​​and / or direct communication information to an upper layer; forwarding a direct communication message to another WTRU and / or a sidelink relay; and discarding sidelink measurement values.

[0255] Representative sidelink measurements

[0256] A WTRU may perform sidelink measurements between itself and one or more other WTRUs and / or one or more sidelink relays. A sidelink measurement value (e.g., a single sidelink measurement value) may be (or be based on) a measurement value of one or more parameters ("sidelink measurement parameters"). The sidelink measurement parameters may include any of the following: (i) CQI; (ii) RSRP; (iii) RSRQ; (iv) path gain; (v) path loss; (vi) the distance between any of two WTRUs, a WTRU and a sidelink relay, two sidelink relays, a WTRU and a network element, and a sidelink relay and a network element; (vii) a reachability indicator (e.g., an indication of whether the WTRU, the sidelink relay, and / or the network element is reachable or unreachable); (viii) a CBR of a resource pool configured to perform sidelink transmissions; and (ix) a CR of a WTRU or a sidelink relay.

[0257] As indicated, the WTRU may consider reachability as a sidelink measurement parameter. The WTRU may determine whether another WTRU, sidelink relay, and / or network element is reachable (or unreachable) based on the HARQ reception status. If the WTRU does not continuously receive the (pre) configured number of expected HARQ feedback (DTX) from the corresponding WTRU, sidelink relay, and / or network element, the WTRU may determine that the other WTRU, sidelink relay, and / or network element is unreachable. Alternatively, if the WTRU receives ACK / NACK feedback from the corresponding WTRU, sidelink relay, and / or network element, the WTRU may determine that the other WTRU, sidelink relay, and / or network element is reachable.

[0258] The WTRU may indicate the presence of a message (e.g., a direct communication message) in an SCI and / or a medium access control (MAC) control element (CE). This indication may be used to support the WTRU, a sidelink relay, and / or a network node (e.g., as an agent thereof) to perform sidelink measurements (e.g., RSRP measurements) of the link corresponding to the message.

[0259] The WTRU may perform and / or maintain sidelink measurements associated with a message (e.g., a direct communication message) that may be distinguished by an L1 ID and an indicator in an SCI and / or MAC CE. For example, upon receipt of a direct communication message, the WTRU may initiate measurement collection for a certain period of time on all transmissions that employ the L1 ID and the message indicator in the SCI and / or MAC CE. The WTRU may perform L3-RSRP measurements by averaging the RSRP measured in each transmission of the message. The filter coefficients may be determined based on any of the following: (i) (pre-)configured per resource pool; (ii) (pre-)configured per service; and (iii) (pre-)configured for one type of message (e.g., a direct communication message).

[0260] In various embodiments, the WTRU may be limited to fixing (setting) the transmission power of messages (e.g., direct communication messages) per L1 ID. For example, the WTRU may be configured to transmit direct communication messages in a shared resource pool using data transmission. The WTRU is (pre) configured to determine the transmission power based on the CBR of the resource pool; the sidelink path loss; and / or the downlink path loss. However, if a direct communication request message is transmitted in the resource pool, the WTRU may determine to fix (set) the transmission power of the message without considering the CBR; the sidelink path loss; and / or the downlink path loss. The value of the transmission power may be (pre) configured according to the service and / or destination ID. In various embodiments, the WTRU may implicitly and / or explicitly indicate the transmission power in the message (e.g., in the SCI and / or MAC CE). For example, the transmission power may be implicitly indicated by another parameter indicated in the SCI of the transmission (e.g., the minimum communication range). The WTRU may determine the transmission power of the message based on the value of the field in the SCI and the associated mapping. Implicit and / or explicit indication of transmit power may be facilitated to support WTRUs, sidelink relays, and / or network nodes in sidelink measurements.

[0261] The WTRU may initiate a timer and / or counter upon receipt of a direct communication for use in conjunction with processing of sidelink measurements. The WTRU may increment the counter after each reception or transmission of a direct communication message. The WTRU may perform various actions upon expiration of a timer and / or a counter meeting a threshold. The various actions may include any of: reporting sidelink measurements and / or direct communication information to an upper layer; forwarding a direct communication message to another WTRU and / or a sidelink relay, and discarding sidelink measurements.

[0262] In various embodiments, the WTRU may use or combine the measurement window and / or the number of direct communication message receptions (e.g., DIRECT_COMM_REQ message receptions) from the same sidelink relay (e.g., the source sidelink relay) for determining a sidelink measurement value associated with the sidelink relay (e.g., the quality of the corresponding sidelink channel). The WTRU may obtain the measurement window and / or the number of direct communication message receptions in various ways. The WTRU may determine the measurement window and / or the number of direct communication message receptions, for example, based on various rules and / or information, including any of the following:

[0263] L1 RSRP measurement value of a single reception of a direct communication message and / or accumulated RSRP measurement value of multiple receptions of one or more direct communication messages. As an example, the WTRU may average the RSRP measurement values ​​of the first several direct communication messages (e.g., DIRECT_COMM_REQ messages) received, and if the L3 RSRP measurement value fails to meet (e.g., is greater than) a first threshold, the WTRU may consider the sidelink relay to be selectable and may stop performing measurements. If the L3 RSRP measurement value fails to meet (e.g., is less than) a second threshold, the WTRU may consider the sidelink relay to be non-selectable and may stop performing measurements. Alternatively, if the L3 RSRP measurement value meets both the first threshold and the second threshold, the WTRU may continue to monitor subsequent direct communication messages from the sidelink relay and / or may perform measurements to determine whether the relay is selectable and / or whether to stop or continue performing measurements. The method may be driven to ensure that the selectable relay has a good sidelink channel.

[0264] QoS of relay service. For example, the WTRU may select a short measurement window for a low-latency (eg, high priority) relay service. Alternatively, the WTRU may select a long measurement window for a delay-tolerant relay service.

[0265] Availability of sidelink relays. The WTRU may select a long measurement window if, for example, the WTRU has a connection with another sidelink relay. Alternatively, the WTRU may select a short measurement window if, for example, the WTRU does not have a connection with any sidelink relay.

[0266] Connection status with an existing sidelink relay. The WTRU may select a short measurement window if, for example, an existing (currently connected) sidelink relay has experienced or is experiencing an AS failure and / or a sidelink measurement value associated with the existing sidelink relay fails to meet (e.g., falls below) a threshold.

[0267] CBR of the resource pool.

[0268] CR of WTRU.

[0269] In various embodiments, the WTRU may obtain the measurement window and / or the number of direct communication messages (e.g., DIRECT_COMM_REQ) received from one or more of the direct communication messages. For example, one, some, or all of the direct communication messages may include information that specifies, defines, and / or is used to configure the measurement window and / or the number of direct communication messages received, and the WTRU may use some or all of this information ("window / reception information") to determine and / or configure the measurement window and / or the number of direct communication messages received. The window / reception information may include, for example, one or more rules for the measurement window, one or more parameters for the measurement window, one or more values ​​for one or more of such parameters, one or more values ​​for the number of direct communication messages received, and the like. Alternatively, the window / reception information may be or include information (e.g., reference information) that may implicitly indicate the measurement window (e.g., its rules, parameters, etc.) and / or the number of direct communication messages received. As an example, the window / reception information (e.g., information specifying, defining, and / or used to configure a measurement window) may include an identifier (ID) of a relay service ("relay service ID") that the WTRU may use to identify and / or obtain a measurement window for the corresponding relay service (e.g., configured based on the corresponding relay service). The window / reception information may be part of or provided along with other information used to facilitate the WTRU to perform sidelink measurements. The window / reception information and / or other information may be populated into the direct communication message by one or more other WTRUs (e.g., either a sidelink relay and a source WTRU).

[0270] In various embodiments, the WTRU may be configured with one or more filter coefficient parameters used in conjunction with determining the L3 RSRP of the side link. In various embodiments, in conjunction with determining the L3 RSRP of the side link for different receptions of the same direct communication message, the WTRU may use different filter coefficient parameters. In various embodiments, each filter coefficient parameter may be associated with a single relay service. The WTRU may determine which filter coefficient parameter (of the one or more filter coefficient parameters) to use based on the directional relay service. In various embodiments, one, some, or all of the filter coefficient parameters may be associated with more than one relay service. The WTRU may determine which filter coefficient parameter to use based on the directional relay service or based on the directional relay service and other criteria. For example, the WTRU may determine that only one filter coefficient parameter (of the one or more filter coefficient parameters) is associated with the directional relay service based on the directional relay service, and may use the one filter coefficient parameter. Alternatively, the WTRU may determine that multiple filter coefficient parameters are associated with the directional relay service based on the directional relay service, and may determine which filter coefficient parameter of the multiple filter coefficient parameters to use based on other criteria. For example, other criteria may include the QoS of the relay service.

[0271] One, some, or all of the direct communication messages (e.g., DIRECT_COMM_REQ message) may include information that specifies, defines, and / or is used to configure filter coefficient parameters (e.g., one or more filter coefficient IEs). The information that specifies, defines, and / or is used to configure filter coefficient parameters may belong to or be provided together with other information that is used to facilitate the WTRU to perform sidelink measurements. The information that specifies, defines, and / or is used to configure filter coefficient parameters and / or other information may be populated into the direct communication message by one or more other WTRUs (e.g., any of the sidelink relay and the source WTRU).

[0272] In various embodiments, the WTRU may determine a sidelink measurement value associated with a source of a direct communication message (e.g., a DIRECT_COMM_REQ message) based on L1 RSRP measurements of multiple transmissions of the (same) direct communication message. As an example, the WTRU may perform L1 RSRP measurements of two or more transmissions (e.g., an initial transmission and / or any of one or more retransmissions) of a direct communication message (e.g., a DIRECT_COMM_REQ message), and may determine a sidelink measurement value associated with a source of the direct communication message based on the L1 RSRP of the two or more transmissions of the direct communication message (e.g., a maximum of the L1 RSRPs, a minimum of the L1 RSRPs, a weighted average L1 RSRP, etc.). The weights may be configured per relay service. The method may be facilitated to reduce delays associated with the discovery process.

[0273] Representative sidelink measurement forwarding and / or reporting

[0274] The side link measurement value may be reported / forwarded in various ways. The various ways may include any of the following: RRC message, MAC CE, SCI (e.g., the 2nd SCI may be used to report the side link measurement value) and upper layer message (e.g., the AS layer may report the side link measurement value to the upper layer and the upper layer may include the measurement value in one of the upper layer messages (e.g., direct communication message)).

[0275] The WTRU may include any of the following information in the sidelink measurements: the CBR of the resource pool; the CR of the WTRU; the QoS of the service; the expected response timing; information about the delay budget of the packet; and the location of the WTRU.

[0276] The sidelink relay may forward the sidelink measurement values ​​of one hop segment (e.g., the hop segment between the sidelink relay and the destination WTRU - the "second hop segment") to another node (e.g., the source WTRU and / or the gNB). The sidelink relay may combine the sidelink measurement values ​​of multiple hop segments (e.g., two hop segments - the hop segment between the source WTRU and the sidelink relay and the hop segment between the same or different sidelink relay and the destination WTRU) to report in the same message. Alternatively, the sidelink relay may report the sidelink measurement values ​​of each hop segment of one or more (e.g., each) of these hop segments separately. The sidelink measurement values ​​of one hop segment (e.g., the first hop segment, the second hop segment, etc.) and / or the combined sidelink measurement values ​​of multiple hop segments may be reported, forwarded, etc. periodically or based on various triggering events. The various triggering events may include any of the following:

[0277] The sidelink measurement value between the source WTRU and the sidelink relay (first hop) meets (e.g., is greater than / less than) a threshold, and / or the sidelink measurement value of the second hop meets (e.g., is greater than / less than) another threshold. The sidelink measurement threshold may be determined based on the QoS of the service.

[0278] In one example, the sidelink relay may perform RSRP measurements for the first hop. The WTRU may be configured to perform RSRP measurements for the reverse link of the second hop. If at least one of the two RSRP measurements meets (e.g., is less than) an RSRP threshold, the WTRU may trigger forwarding of the RSRP measurement value for the second hop.

[0279] In another example, the WTRU may be configured to receive an RSRP sidelink measurement of the second hop from the destination WTRU. The WTRU may be configured to perform an RSRP measurement of the first hop. If at least one of the two RSRP measurements meets (e.g., is less than) a threshold, the WTRU may trigger forwarding the RSRP measurement of the second hop.

[0280] The sidelink of one hop (e.g., the second hop) becomes reachable / unreachable. For example, the sidelink relay may transmit an indication to the source WTRU to indicate that the reachability state of the second hop has changed (e.g., from reachable to unreachable or from unreachable to reachable).

[0281] The sidelink relay receives an indication from another WTRU (e.g., a source WTRU or a destination WTRU) to report sidelink measurements for a first hop and / or a second hop. For example, the sidelink relay may receive an indication in an SCI (e.g., a bit field in which the WTRU may use the first SCI and / or the second SCI or a dedicated second SCI format) and / or a MAC CE to report the sidelink measurements for the second hop. Upon receipt of such an indication, the sidelink relay may report the sidelink measurements to the source WTRU.

[0282] The sidelink relay may receive a sidelink measurement value for a hop (e.g., a second hop). In one example, the sidelink relay may forward the sidelink measurement value for the second hop whenever the sidelink relay receives a sidelink measurement value report from the destination WTRU. In another example, the sidelink relay may forward the sidelink measurement value for the second hop if the sidelink measurement value meets (e.g., is less than and / or greater than) one or more thresholds.

[0283] The CBR of the resource pool satisfies (e.g., is greater than and / or less than) a threshold, and / or the CR of the sidelink relay satisfies (e.g., is greater than) a threshold. For example, the sidelink relay may be (pre-)configured to forward the sidelink measurement value of the second hop segment and / or report the sidelink measurement value of the first hop segment when the CBR of the resource pool satisfies (e.g., is less than / greater than) a threshold and / or the CR of the sidelink relay satisfies (e.g., is greater than) a threshold.

[0284] The transmission power of the sidelink relay and the WTRU in one hop segment (the second hop segment) meets (e.g., is greater than / less than) a threshold. For example, if the transmission power of the second hop segment meets (e.g., is greater than / less than) the threshold, the sidelink relay may forward the sidelink measurement value of the second hop segment. In one method, the sidelink relay may trigger reporting of the sidelink measurement value of the second hop segment to the source WTRU if its transmission power meets (e.g., is greater than / less than) the threshold. In another method, the sidelink relay may receive the transmission power information of the destination WTRU (e.g., via a transmitted SCI), and if the indicated transmission power meets (e.g., is less than / greater than) the threshold, the sidelink relay may trigger reporting of the sidelink measurement value of the second hop segment to the source WTRU.

[0285] The sidelink relay receives a request for sidelink measurement values ​​from another node (e.g., another WTRU or a gNB). The triggering conditions for transmitting the request message may be (pre-)configured per resource pool or it may be configured via PC5 RRC. The request message may be conveyed via PC5 RRC.

[0286] A WTRU (e.g., a source WTRU) may receive a message (e.g., a DIRECT_COMM_REQ message) from another node (e.g., another sidelink relay). As an example, a sidelink relay may receive a direct communication message (e.g., a DIRECT_COMM_REQ message) transmission from another sidelink relay, and the RSRP (or other sidelink measurement) of the direct communication message transmission may meet (e.g., be greater than) a threshold. The WTRU (e.g., a source WTRU) may request reporting of sidelink measurements (e.g., sidelink reference signal received power (SL-RSRP) measurements) to evaluate a current link. If the sidelink measurement offset between the current link and the detected link meets (e.g., is greater than) a threshold, the WTRU (e.g., the source WTRU) may perform relay reselection.

[0287] The WTRU may trigger a sidelink measurement report of a parameter based on the measurement of the same parameter or another parameter. The WTRU may trigger a sidelink measurement report of the parameter if the sidelink measurement of the parameter and / or the other parameter meets (e.g., is greater than / less than) the corresponding threshold. For example, the destination WTRU may trigger an RSRP measurement report if the distance of the second hop meets (e.g., is greater than / less than) the threshold. Alternatively, the WTRU may trigger a distance report if the distance of the second hop meets (e.g., is greater than / less than) the threshold.

[0288] The sidelink relay may trigger CSI-RS transmission to the source / destination WTRU and / or may determine any characteristics associated with CSI-RS transmission / reporting based on various information. The various information may include any of the following:

[0289] Other measurement values: The sidelink measurement values ​​of the first hop segment and / or the second hop segment meet (eg, are smaller than / greater than) corresponding thresholds.

[0290] Distance: For example, if the distance of the first hop segment and / or the second hop segment meets (eg, is less than) a corresponding threshold.

[0291] CBR: For example, the CBR of the resource pool meets (eg, is greater than / less than) a threshold.

[0292] QoS of the relay link and / or SLRB to be relayed: For example, the sidelink relay may configure a certain pattern of CSI-RS and / or trigger CSI-RS reporting at a certain period. The period may depend on (e.g., based on) the QoS of the SLRB and / or LCH to be relayed.

[0293] The configuration of measurements on one link / hop may depend on (e.g., be based on) the values ​​and / or configuration of measurements on another hop. For example, the configuration of a measurement (e.g., CQI RS periodicity, RSRP reporting periodicity, etc.) determined by one WTRU (where such measurement may be performed by that WTRU (e.g., CBR) or by a receiver WTRU (e.g., RSRP, CQI)) may depend on a configured aspect and / or value of another measurement (of the same type or a different type) where such other measurement is configured by another WTRU (e.g., a transmitter or receiver WTRU). Any of the measurements disclosed herein may be used (possibly in combination) in such an implementation. The WTRU may determine the configuration of RSRP and / or CSI RS transmission based on the value of a CQI measurement or RSRP measurement configured by another WTRU. Alternatively, the WTRU may determine the configuration of RSRP and / or CSI RS transmission based on the configuration of the same or other measurements performed by another WTRU. The WTRU may have an association of WTRUs, which may trigger such dependencies, whereby such association is based on the path of the relay link (e.g., when a sidelink relay acts as a relay between a source and a destination, the sidelink relay may have an association of its measurements configured to the destination WTRU based on measurements configured by the source WTRU). In such embodiments, the measurement configuration may include any of the following: how often measurements are performed and / or reports are transmitted; how often reference signals are transmitted; which event(s) may be configured and / or enabled to report measurement values; parameters associated with the determination of the event that triggers reporting (e.g., thresholds, hysteresis, etc.); etc.

[0294] As an example, a first WTRU (sidelink relay) may determine the periodicity of RSRP measurements to be reported by a second WTRU (destination WTRU) based on the periodicity of RSRP measurements to be performed by the first WTRU configured by a third WTRU (source WTRU). The first WTRU (sidelink relay) may use the same periodicity as the periodicity configured by the third WTRU (source WTRU) or may use a periodicity that is a function of the periodicity configured by the third WTRU (source WTRU).

[0295] As another example, a first WTRU (sidelink relay) may determine a periodicity of RSRP measurements to be reported by a second WTRU (destination WTRU) based on a measurement value of RSRP measurements to be performed by the first WTRU configured by a third WTRU (source WTRU). The first WTRU (sidelink relay) may select a first periodicity when its own measurement value of RSRP is below a threshold, and may select a second periodicity when the RSRP measurement value is above a second threshold.

[0296] Representative message forwarding

[0297] The WTRU (e.g., a sidelink relay) may determine to forward a message (e.g., a direct communication message) and may perform forwarding of the message. The forwarding of the message may include any of the following:

[0298] The AS layer may report information on the reception of the message (eg, the direct communication message) and the associated side link measurement value (eg, the RSRP measurement value corresponding to the message) to the upper layer.

[0299] The AS layer may indicate to the upper layer the necessity of forwarding the message (eg, direct communication message) and / or the need for forwarding the message.

[0300] The WTRU may prepare another message (e.g., another direct communication message) corresponding to the received message (e.g., the received direct communication message), which may include any of the following:

[0301] Modify the source information of the message (for example, add relay ID information); and

[0302] Add any of the following information:

[0303] Sidelink measurements (e.g., sidelink measurements of the first hop between itself and the source WTRU and / or Uu RSRP);

[0304] CBR of the resource pool and / or CR of the sidelink relay;

[0305] QoS of the service (which may include, for example, one or more SLRB configurations, one or more resource pool configurations, one or more supported priorities, one or more supported delays, one or more supported data rates, etc.);

[0306] expected response timing and / or information about the delay budget of the packet;

[0307] the location of the WTRU;

[0308] An indication of the WTRU's load (which may include, for example, buffer status information, number of connected UEs, etc.);

[0309] The RRC state of the WTRU (e.g., connected, idle, inactive);

[0310] with one or more WTRUs (eg, source and / or destination) requesting relay service.

[0311] any of one or more IDs (e.g., UE ID) associated with a WTRU;

[0312] one or more RSRPs associated with the one or more WTRUs (or one or more IDs (e.g., UE IDs) associated with such WTRUs) requesting relay service;

[0313] Resource pool configuration / information for data communication, which may include, for example, any of the following:

[0314] HARQ resource configuration and / or indication thereof; and

[0315] one or more resources for communicating and / or indications thereof; and

[0316] One or more capabilities of sidelink relay and / or one or more remote WTRUs, which may include, for example, any of the following:

[0317] Transmit power level;

[0318] MIMO capability;

[0319] sensing capabilities (e.g., partial sensing, no sensing, and full sensing) of the sidelink relay and / or the one or more remote WTRUs;

[0320] one or more supported MCSs or indications thereof (e.g., an indication of a table of MCSs that may be supported); and

[0321] One or more supported carriers or indications thereof.

[0322] The WTRU may trigger the transmission of the message (eg, a direct communication message).

[0323] The WTRU may forward a message (e.g., a direct communication message) based on any of the following: (i) the received signal strength of the message (e.g., the direct communication message); (ii) a measurement value configured for the message, such as disclosed herein; (iii) the distance between the sidelink relay WTRU and the source WTRU and / or the distance between the sidelink relay WTRU and the destination WTRU; (iv) the QoS requirements of the service; (v) the location of the WTRU; (vi) the CBR of the resource pool and / or the CR of the sidelink relay; (vii) the speed of the WTRU; (viii) the number of relay links and / or SLRBs currently established at the WTRU; and (ix) previous reception of other related direct communication messages associated with the same relay reselection event (e.g., a sidelink relay or destination WTRU may forward up to N direct communication messages associated with the same source WTRU (where N may be 1). After forwarding N direct communication request messages, if any other direct communications are associated with the same relay reselection event, the WTRU may discard them).

[0324] The WTRU may determine to forward a message (e.g., direct communication) from a source WTRU and decide to become a relay for the source WTRU based on a sidelink measurement between the WTRU and the source WTRU and / or a sidelink measurement between the WTRU and the destination WTRU (e.g., an RSRP measurement of the message). For example, if the sidelink measurement is within a (pre-)configured range, the WTRU may forward a message (e.g., a direct communication message) from the source WTRU.

[0325] As an example, the WTRU may forward a message (e.g., a direct communication message) if the RSRP measured in the message is greater than a threshold and / or less than another threshold. Alternatively, the WTRU may forward the message if the sidelink path loss between the source and relay WTRUs is less than a threshold and / or greater than another threshold.

[0326] As another example, if the RSRP or sidelink path loss between the WTRU and the destination WTRU is less than a threshold and / or greater than another threshold, the WTRU may forward the message (e.g., a direct communication message). The destination WTRU may be indicated in the direct communication, and the RSRP or SL path loss between the WTRU and the destination WTRU may be obtained from an existing unicast link between the relay WTRU and the destination WTRU.

[0327] The WTRU may determine to forward a message (e.g., a direct communication message) from a source WTRU based on a distance between the WTRU and the source WTRU and / or a distance between the WTRU and the destination WTRU. For example, if the distance between the WTRU and the source WTRU and / or the distance between the WTRU and the destination WTRU is greater than one (pre) configured threshold and / or less than another (pre) configured threshold, the WTRU may relay the message. These thresholds may be determined based on a minimum communication range associated with the service.

[0328] The WTRU may determine to forward a message (e.g., a direct communication message) based on the QoS requirements of the service. For example, the WTRU may determine to relay the message based on any of various QoS parameters. The various QoS parameters may include any of: (i) priority, latency, reliability, and / or data rate associated with the service; and (ii) minimum communication range associated with the service.

[0329] The QoS parameters associated with the service may be implicitly indicated in the message. Each QoS parameter associated with the service may be determined based on the minimum / maximum values ​​of the data associated with the service. The WTRU may be (pre-)configured with a set of services, any one (e.g., each) of which may be associated with a set of QoS parameters. The WTRU may determine the QoS parameters corresponding to the service indicated in the message (e.g., direct communication message).

[0330] The WTRU may determine to forward the message (e.g., a direct communication message) based on any of the priority, latency, and / or reliability of the service. For example, the WTRU may first determine whether it can meet the required QoS (e.g., priority, latency, reliability, and data rate) requested by the source WTRU, which may be indicated in the message. If it can meet the required QoS of the source WTRU, the WTRU may forward the message.

[0331] The WTRU may determine to forward a message (e.g., a direct communication message) based on the required communication range. For example, if the required communication range of the service is greater than a threshold and / or the distance between the WTRU and the source WTRU is less than a function of the minimum communication range, the WTRU may determine to forward the message.

[0332] The WTRU may determine to forward a message (e.g., a direct communication message) based on the location of the WTRU. For example, the WTRU may be (pre-)configured with a set of zones to initiate relay functionality. The WTRU may forward the message if its zone ID belongs to the set of allowed zones.

[0333] The WTRU may determine the allowed zones based on a function of its WTRU ID (provided by upper layers) so that upper layers can control which WTRUs may act as relays. This approach may be driven to limit the number of relays in a particular area.

[0334] As an example, a WTRU may receive a location / zone associated with a source WTRU and determine whether to forward a direct communication message based on its own location and the location / zone of the source WTRU. For example, the WTRU may receive the location / zone of the source WTRU in a direct communication message or in another AS message transmitted before / during / after the direct communication message. The sidelink relay may be configured with rules regarding whether to relay a direct communication message based on the distance between the source WTRU and the destination WTRU and / or the location of the relay WTRU. For example, the relay WTRU may forward the message if any of the following is met: (i) the distance between the source WTRU and the relay WTRU (e.g., determined based on the zone ID) meets (e.g., is below) a threshold; (ii) the distance between the source WTRU and the sidelink relay WTRU (e.g., determined based on the zone ID) meets (e.g., is above) a threshold; and (iii) the sidelink relay is configured to be a relay in a specific zone in which it is located (e.g., the sidelink relay may be configured with a list of zones in which it is allowed to forward the message, and the sidelink relay may forward the message when it is currently located in one of these zones).

[0335] The WTRU may determine to forward a message (e.g., a direct communication message) based on the CBR of the resource pool and / or the CR of the sidelink relay. For example, if the CBR of the resource pool is less than a threshold and / or the CR of the relay is less than a threshold, the WTRU may determine to forward the message. The CR and / or CBR thresholds may be (pre)configured per service.

[0336] The WTRU may determine to forward a message (e.g., a direct communication message) based on the speed of the WTRU or the relative speed between the WTRU and the source WTRU. For example, the WTRU may be (pre-)configured with a maximum speed threshold to determine whether it can relay the message. If the WTRU speed is less than the threshold, the WTRU may forward the message; otherwise, it is not allowed to forward the message. The speed threshold may be (pre-)configured for each service based on the QoS requirements of the service.

[0337] Representative relay / path (re)selection

[0338] The WTRU may perform path selection. Performing path selection may include selecting an appropriate path (e.g., a particular sidelink relay, a direct path, etc.). Selecting the appropriate path may be based on the receipt of multiple direct communication messages originating from the same source WTRU (e.g.). The WTRU may perform path selection by either: (i) transmitting a response message and (ii) notifying an upper layer of the selected path. The response message may indicate the selected path (e.g., include information specifying the selected path). The response message may be transmitted only to the indicated / specified path (e.g., a sidelink relay associated with the selected path).

[0339] The WTRU may perform path selection after receiving a direct communication message based on any of the following: (i) the number of hops; (ii) sidelink measurement values, such as combined sidelink measurements of multiple hops; (iii) QoS of the service; (iv) reception timing of the direct communication message; (v) resource pool information; (vi) the distance between the WTRU and the sidelink relay; and (vii) one or more capabilities of the sidelink relay.

[0340] In various embodiments, the WTRU may perform path selection based on the QoS of the service. As an example, for each service that may have one or more associated QoS profiles, the WTRU may be (pre-)configured with any of: (i) a combined sidelink measurement value for multiple hops required; (ii) a maximum number of hops; and (iii) a reception time for direct communication messages.

[0341] The WTRU may determine a path that meets the QoS requirements of the service. If there are multiple paths that meet the QoS requirements, the WTRU may further select a path based on other criteria.

[0342] The WTRU may prioritize paths with fewer hops. For example, the WTRU may prioritize paths with fewer hops if other criteria are met. The other criteria may include any of the following: (i) the sidelink measurement in each hop of the path is greater than a threshold; and (ii) the distance in each hop of the path is less than a threshold.

[0343] For example, Figure 4 As shown, the destination WTRU has two paths between the source WTRU and the destination WTRU to choose from. The first path is a direct link (i.e., a single hop) between the source and destination WTRUs. The second path is via a relay WTRU (e.g., two hops). If the sidelink measurement between the source and destination WTRUs meets (e.g., is greater than) a threshold, the WTRU prioritizes the direct link path.

[0344] The WTRU may prioritize one path over another based on the combined sidelink measurements of multiple hops in the path. For example, the WTRU may prioritize the path with the lowest / highest value based on the combined sidelink measurements of the hops in the path. The WTRU may be (pre)configured with various functions for performing path selection based on the combined sidelink measurements, and may use any of the various functions to perform path selection. The function may be the weighted total sidelink measurement in each hop. For example, the WTRU may select the path with the maximum weighted total sidelink measurement. Alternatively and / or additionally, the function may be the minimum sidelink measurement across all hops in the path. For example, the WTRU may select the path with the maximum value of the minimum sidelink measurement.

[0345] In another method, the WTRU may prioritize the path with the highest sidelink measurement value for a particular hop, given that the sidelink measurement value for every other hop is greater than a (pre-)configured threshold. The particular hop to be considered may be the last hop, the first hop, or any hop between the first and last hops. For example, for two-hop path selection, the destination WTRU may select the path with the highest sidelink measurement value in the second hop (the hop from the relay to the destination WTRU), given that the RSRP of the first hop is greater than a threshold.

[0346] The WTRU may receive direct communication messages from multiple paths. The WTRU may select a path based on the time at which the direct communication message was received. For example, if the WTRU receives a message that meets the QoS requirements, the WTRU may determine to select a first path.

[0347] In various embodiments, the WTRU may select a path based at least in part on information about a resource pool of a sidelink relay. The sidelink relay may indicate resource pool information corresponding to a resource pool configured and / or used for data communication in a direct communication message. The resource pool information may include, for example, the availability of HARQ resources, the CBR of the resource pool, etc. The WTRU may receive a direct communication message and may use some or all of the resource pool information in conjunction with determining and / or selecting a path. The WTRU may, for example, prioritize sidelink relays based on the resource pool information and may select a sidelink relay when, for example, the sidelink relay is assigned the highest priority (and / or meets other criteria). If, for example, the resource pools of other sidelink relays do not support HARQ transmission and the resource pool information indicates that the resource pool supports HARQ transmission, the WTRU may assign a higher priority to the sidelink relay than to the other sidelink relays. Alternatively, if, for example, the resource pool of the other sidelink relay has a higher CBR than the CBR of the resource pool information indicated by the resource pool information, the WTRU may assign a higher priority to the sidelink relay than the other sidelink relay. The WTRU may assign a priority to the sidelink relay based on a combination of information indicated by the resource pool information. In various embodiments, the WTRU may not exclude the sidelink relay (e.g., keep it as a candidate) if the data resource pool of the sidelink relay is greater than a threshold. The threshold may be configured per relay service.

[0348] In various embodiments, the WTRU may select a path based at least in part on the distance between the sidelink relay and the WTRU. The WTRU may prioritize the sidelink relay, for example, based on the distance between the sidelink relay and the WTRU, and may select the sidelink relay when, for example, the sidelink relay is assigned the highest priority (and / or meets other criteria). If, for example, the sidelink relay is closer to the WTRU than other sidelink relays, the WTRU may assign a higher priority to the sidelink relay than the other sidelink relays. In various embodiments, the WTRU may exclude the sidelink relay as a candidate if, for example, the distance between the sidelink relay and the WTRU is greater than a threshold. The threshold may be configured per relay service.

[0349] In various embodiments, the WTRU may select a path based at least in part on one or more capabilities of the sidelink relay. The WTRU may, for example, prioritize sidelink relays based on the capabilities of the sidelink relays, and may select a sidelink relay when, for example, the sidelink relay is assigned the highest priority (and / or meets other criteria). If, for example, the sidelink relay supports a greater transmission power than supported by the other sidelink relays, the WTRU may assign a higher priority to the sidelink relay than the other sidelink relays. Alternatively, if, for example, the sidelink relay supports full sensing capability and the other sidelink relays support partial sensing capability or no sensing capability, the WTRU may assign a higher priority to the sidelink relay than the other sidelink relays.

[0350] The WTRU may maintain a timer to receive multiple transmissions of a message (e.g., a direct communication message). The WTRU may be configured with a timer to perform path selection. An initial value for the timer may be delivered to the WTRU via a direct communication message. Alternatively, the initial value for the timer may be determined based on any combination of: (i) a value (pre-)configured per service; and (ii) a CBR of a resource pool.

[0351] The WTRU may initiate a timer after receiving the first direct communication message. After the timer expires, the WTRU may perform any of the following: (i) perform relay selection and respond to the direct communication message; and (ii) report information about the detected path to the upper layer.

[0352] The WTRU's AS layer may report the path to the upper layer to support the upper layer in path selection and / or response to direct communication messages. The information may include one or more of the following: (i) source ID; (ii) relay ID group; (iii) sidelink measurement values ​​for each hop; and (iv) associated QoS of the service.

[0353] The WTRU (e.g., its AS layer) may select a set of paths to be reported to the upper layer. In one method, the WTRU may report the selected paths to the upper layer, or it may report all detected paths to the upper layer. Alternatively, the WTRU may report a (pre)defined number of paths to the upper layer. The WTRU may eliminate one or more paths as candidates for reporting. The WTRU may eliminate the path as a candidate for reporting based on the combined sidelink measurement values ​​of multiple hops in the path. For example, if the sidelink measurement values ​​of multiple hops in the path are less than or greater than a threshold, the WTRU may eliminate the path. The WTRU may eliminate the path as a candidate for reporting based on the number of successful receptions in a path. For example, the WTRU may perform reception of direct communications corresponding to a path. If the number of TBs and / or messages received from the path is less than a threshold, the WTRU may eliminate the path. The WTRU may eliminate one or more paths as candidates for reporting based on the QoS of the service and any of the CBR of the resource pool and / or the CR of the WTRU. The WTRU may eliminate the path as a candidate for reporting based on the number of hops in the path. For example, the WTRU may eliminate paths having a number of hops greater than a threshold. The threshold may be determined based on the QoS of the service and / or the CBR of the resource pool and / or the CR of the WTRU.

[0354] The WTRU may perform path (re)selection based on any of the following:

[0355] Combined sidelink measurements for the current path. The combined sidelink measurements for the current path may be determined based on either: (i) sidelink measurements determined using measurements of data transmissions in the path; and (ii) sidelink measurements determined using measurements of specific messages (e.g., direct communication messages).

[0356] Combined sidelink measurement value of the new path. The combined sidelink measurement value of the new path may be obtained based on the sidelink measurement value of a specific message (eg, a direct communication message).

[0357] The number of hops per path.

[0358] QoS of the service.

[0359] As an example, the WTRU may perform path selection if the combined sidelink measurement value of the current path is less than / greater than a threshold. The threshold may be (pre-)configured based on the QoS of the service.

[0360] As another example, the WTRU may reselect a new path if the sidelink measurement of the new path meets the QoS of the service (eg, the combined RSRP is less than a threshold) and the number of hops in the new path is less than the number of hops in the current path.

[0361] As another example, if the combined sidelink measurement value of the new path is greater than a threshold and / or the combined sidelink measurement value of the current path is less than a threshold and / or the difference between the sidelink measurement values ​​of the current path and the new path is greater than / less than a delta threshold, the WTRU may reselect a new path. The delta threshold may be determined based on the number of hops in each path and / or the QoS of the service.

[0362] In various embodiments, a WTRU (e.g., a source WTRU) may determine a sidelink measurement value for a path. The WTRU may determine the sidelink measurement value for the path, for example, based on one or more sidelink measurement values ​​for some or all hops of the path. For example, in various embodiments, the WTRU may determine that the sidelink measurement value for the path may be the sidelink RSRP ("SL-RSRP") or the accumulated SL-RSRP of a first hop. In various embodiments, the WTRU may determine that the sidelink measurement value for the path may be the SL-RSRP or the accumulated SL-RSRP of a second hop. In various embodiments, the WTRU may determine that the sidelink measurement value for the path may be a combination of the SL-RSRPs of multiple hops ("combined SL-RSRP"), such as, for example, any of the maximum and / or minimum values ​​of the SL-RSRP for each of the multiple hops. For example, the sidelink measurements for a path may not include sidelink measurements for all of its hops because the WTRU does not have sidelink measurements associated with one or more of the hops and / or makes a decision not to use sidelink measurements associated with one or more of the hops.

[0363] Figure 5 An example of sidelink measurements associated with a path including multiple hops is shown. As shown, the sidelink measurement for any hop of the path may be (i) a sidelink measurement of a transmission received by a sidelink relay, WTRU (e.g., source WTRU), base station, etc. ("Rx SL measurement"), (ii) an accumulation or other combination of multiple Rx SL measurements ("accumulated Rx SL measurement"), (iii) a reported / forwarded sidelink measurement of a transmission transmitted by a sidelink relay, WTRU (e.g., source WTRU), base station, etc. ("Tx SL measurement"), and / or (iv) a reported / forwarded accumulation or other combination of multiple Tx SL measurements ("accumulated Tx SL measurement"). For simplicity of explanation, the terms “Rx SL measurement value” and “accumulated Rx SL measurement value” may be collectively referred to as “Rx SL measurement value” herein, and the terms “Tx SL measurement value” and “accumulated Tx SL measurement value” may be collectively referred to as “Tx SL measurement value” herein.

[0364] The Rx SL measurement value may include any one of a sidelink measurement value for data transmission and a sidelink measurement value for discovery transmission. The Tx SL measurement value may include any one of a sidelink measurement value for data transmission and a sidelink measurement value for discovery transmission. The sidelink measurement value of discovery transmission (e.g., RSRP measurement value) may be referred to as a sidelink discovery transmission measurement value (e.g., SD-RSRP measurement value).

[0365] The sidelink relay and / or the WTRU (e.g., the source WTRU) may determine the sidelink measurement value (e.g., the SL-RSRP measurement value) of the hop segment using or based on any of the following: (i) one or more Rx SL measurement values ​​(e.g., the Rx-RSRP measurement value) of one or more sidelink transmissions received at the WTRU; (ii) one or more Tx SL measurement values ​​(e.g., the Tx-RSRP measurement value) reported / forwarded to the sidelink relay and / or the WTRU; (iii) one or more sidelink measurement values ​​of one or more data transmissions in the hop segment; and (iv) one or more sidelink measurement values ​​of one or more specific message (e.g., one or more DIRECT_COMM_REQ messages) transmissions in the hop segment.

[0366] In various embodiments, the sidelink relay and / or WTRU may determine the SL-RSRP of the hop segment as a function of any of the Tx-RSRP measurement value and the Rx-RSRP measurement value. The sidelink relay and / or WTRU may determine the SL-RSRP of the hop segment, for example, as any of the following: the maximum value of the Tx-RSRP measurement value and the Rx-RSRP measurement value, the minimum value of the Tx-RSRP measurement value and the Rx-RSRP measurement value, the average value of the Tx-RSRP measurement value and the Rx-RSRP measurement value, one of the Tx-RSRP measurement value and the Rx-RSRP measurement value, etc. In some scenarios, for example, when SL-RSRP measurement value reporting is enabled, the sidelink relay and / or WTRU may determine that the SL-RSRP of the hop segment may be the Tx-RSRP measurement value. In some other scenarios, for example, when SL-RSRP measurement value reporting is disabled, the sidelink relay and / or WTRU may determine that the SL-RSRP of the hop segment may be the Rx-RSRP measurement value. And in other scenarios, the sidelink relay and / or WTRU may determine that the SL-RSRP of the hop segment may be the maximum / minimum value of the Tx-RSRP measurement value and the Rx-RSRP measurement value.

[0367] In various embodiments, the sidelink relay and / or the WTRU may determine the sidelink measurement value (e.g., SL-RSRP measurement value) of the hop segment as a function of the sidelink measurement value of the data transmission and / or the sidelink measurement value (e.g., SL-RSRP measurement value) transmitted by one or more direct communication messages (e.g., DIRECT_COMM_REQ messages). The sidelink relay and / or the WTRU may determine the SL-RSRP of the hop segment, for example, as any of the following: the maximum of the sidelink measurement value of the data transmission and the sidelink measurement value transmitted by the direct communication message, the minimum of the sidelink measurement value of the data transmission and the sidelink measurement value transmitted by the direct communication message, a weighted average of the sidelink measurement value of the data transmission and the sidelink measurement value transmitted by the direct communication message, one of the sidelink measurement value of the data transmission and the sidelink measurement value transmitted by the direct communication message, etc. In some scenarios, the sidelink relay and / or the WTRU may determine that the sidelink measurement value (e.g., SL-RSRP measurement value) of the hop segment may be the sidelink measurement value (e.g., SL-RSRP measurement value) transmitted by the direct communication message (e.g., DIRECT_COMM_REQ message). In some other scenarios, the sidelink relay and / or the WTRU may determine that the sidelink measurement value (e.g., SL-RSRP measurement value) of the hop segment may be the sidelink measurement value (e.g., SL-RSRP measurement value) of the data transmission. And in other scenarios, the sidelink relay and / or the WTRU may determine that the sidelink measurement value (e.g., SL-RSRP measurement value) of the hop segment may be the maximum / minimum value of the sidelink measurement value (e.g., SL-RSRP measurement value) of the data transmission and the sidelink measurement value (e.g., SL-RSRP measurement value) transmitted by the direct communication message (e.g., DIRECT_COMM_REQ message).

[0368] The WTRU may determine the type of transmission of sidelink measurement values ​​to be used for a hop segment ("transmission type"). The transmission type may include a sidelink data transmission and / or a discovery transmission. In various embodiments, the WTRU may determine a transmission type (e.g., a sidelink data transmission and / or a discovery transmission) and / or one or more sidelink measurement parameters (e.g., SD-RSRP measured from a discovery transmission or SL-RSRP measured from a data transmission) for use in evaluating a sidelink channel between the WTRU and another WTRU (e.g., a sidelink channel between a source WTRU and a sidelink relay). The WTRU may determine the sidelink transmission type (e.g., sidelink data transmission and / or discovery transmission) based on any of the following: (i) a network indication, (ii) the availability of sidelink data and / or discovery transmission, (iii) the RRC state of the WTRU, (iv) the SL-DRX state of the WTRU, and (v) the Uu-DRX state of the WTRU. For example, the WTRU may be (pre)configured by the network and / or receive information from the network indicating a transmission type for evaluating a sidelink channel (e.g., an indicator of the transmission type). The WTRU may use the indicated / (pre)configured transmission type to evaluate the sidelink channel. As another example, the WTRU may use sidelink data transmission to evaluate the sidelink channel when sidelink data (and / or sidelink data transmission) is available, and may use sidelink discovery transmission when sidelink data (and / or sidelink data transmission) is not available. If sidelink data and / or sidelink data transmission and discovery information and / or discovery transmission are not available, the WTRU may consider (e.g., declare) that the sidelink channel is unreachable. As another example, if the WTRU is in an RRC idle state or an RRC inactive state, the WTRU may use discovery transmission to evaluate the sidelink channel. If the WTRU is in an RRC connected state, the WTRU may use either sidelink data transmission and discovery transmission to evaluate the sidelink channel. As another example, the WTRU may determine the type of transmission to be used to evaluate the sidelink channel based on the SL-DRX state of the WTRU. The WTRU may, for example, use discovery transmissions to evaluate the sidelink channel with a peer UE when SL-DRX is (pre-)configured. Alternatively, the WTRU may use sidelink data to evaluate the sidelink channel when SL-DRX is not (pre-)configured. Alternatively, the WTRU may use discovery transmissions to evaluate the sidelink channel when the WTRU is in SL-DRX off duration and may use sidelink data to evaluate the sidelink channel when the UE is in SL-DRX on duration.

[0369] As another example, the WTRU may use discovery transmissions to evaluate a sidelink channel with a peer UE when Uu-DRX is (pre-)configured. Alternatively, the WTRU may use sidelink data to evaluate a sidelink channel when Uu-DRX is not (pre-)configured. Alternatively, the WTRU may use discovery transmissions to evaluate a sidelink channel when the WTRU is in Uu-DRX off duration and may use sidelink data to evaluate a sidelink channel when the UE is in Uu-DRX on duration.

[0370] In various embodiments, the WTRU may determine any of the availability of sidelink data and the availability of discovery data. The WTRU may determine the availability of sidelink data for a sidelink channel based on any of the following: (i) the RRC state of the WTRU, (ii) the availability of data within the sliding window, (iii) the SL-DRX state, and (iv) the Uu-DRX state. For example, the WTRU may determine that the sidelink data is available when the SL-DRX is not (pre) configured. Alternatively, the WTRU may determine that the sidelink data is available or unavailable when the SL-DRX is (pre) configured. The UE may, for example, determine that the sidelink data is available when the UE is in the SL-DRX on duration. As another example, the WTRU may determine that the sidelink data is available when the Uu-DRX is not (pre) configured. Alternatively, the WTRU may determine that the sidelink data is available or unavailable when the Uu-DRX is (pre) configured. The UE may, for example, determine that the sidelink data is available when the UE is in the Uu-DRX on duration.

[0371] In various embodiments, the WTRU may be (pre)configured with conditions for determining whether sidelink data and / or discovery data are available (and / or unavailable). The WTRU may, for example, be (pre)configured with information to form a sliding window and may use such information to form a sliding window. If the WTRU has not received sidelink data or the amount of sidelink data received from another WTRU is less than a (pre)configured threshold, the WTRU may assume that it has no sidelink data. The size of the sliding window and / or the threshold for sidelink data may be configured or (pre)configured by the network.

[0372] In various embodiments, the WTRU may be (pre)configured with information forming a sliding window and / or a data threshold to determine whether sidelink data is available. If, for example, the WTRU is in RRC connected mode, the WTRU may use (pre)configured parameters to determine the availability of sidelink data. The WTRU may be configured not to use (pre)configured parameters (e.g., sliding window and data threshold) when the WTRU is in RRC idle mode and / or RRC inactive mode, and may determine that sidelink data is not available when it is in RRC idle mode or RRC inactive mode.

[0373] The sidelink relay and / or the WTRU (e.g., the source WTRU) may determine which of one or more sidelink measurements (e.g., a sidelink measurement for data transmission, a sidelink measurement for discovery transmission, a Tx SL measurement, an Rx SL measurement, etc.) to use in conjunction with the sidelink measurement for determining a hop segment. The sidelink relay and / or the WTRU may determine which of the sidelink measurements to use in conjunction with the sidelink measurement for determining a hop segment, for example, based on any of the following:

[0374] (Pre)Configuration.

[0375] In various embodiments, the sidelink relay and / or the WTRU may be (pre-)configured to use one of the sidelink measurements (e.g., Tx SL measurement value or Rx SL measurement value) in conjunction with the sidelink measurement value for determining the hop segment (e.g., based on any of one or more data / discovery transmissions). The sidelink relay and / or the WTRU may transmit / receive a transmission including information for configuring the sidelink measurement value (e.g., Tx SL measurement value or Rx SL measurement value) to be used. The sidelink relay and / or the WTRU may receive / transmit the transmission using one or more of various protocols, including an RRC protocol, such as using PC5-RRC and / or Uu RRC protocol.

[0376] In various embodiments, the sidelink measurement values ​​to be used (eg, Tx SL measurement values ​​or Rx SL measurement values) may be (pre-)configured per resource pool.

[0377] In various embodiments, the sidelink relay and / or the WTRU may be (pre-)configured with one or more indications of which of the sidelink measurements (e.g., Tx SL measurements or Rx SL measurements) may take precedence over the other, or rules for determining this. As an example, the sidelink relay and / or the WTRU may use the Tx SL measurements when available; otherwise, the sidelink relay and / or the WTRU may use the Rx SL measurements. As another example, the sidelink relay and / or the WTRU may use the sidelink discovery transmission measurements (e.g., SD-RSRP measurements) when available, otherwise the sidelink relay and / or the WTRU may use the sidelink measurements of the data transmission (e.g., Tx SL measurements of the data transmission, Rx SL measurements of the data transmission, or a combination of Tx SL measurements and Rx SL measurements of the data transmission). As another example, the sidelink relay and / or the WTRU may be configured to enable / disable sidelink measurement value reporting. If sidelink measurement reporting is enabled, the sidelink relay and / or WTRU may use Tx SL measurements (e.g., Tx-RSRP measurements); otherwise, the sidelink relay and / or WTRU may use Rx SL measurements (e.g., Rx-RSRP measurements) or a combination of Tx SL measurements and Rx SL measurements. As another example, the sidelink relay and / or WTRU may be configured to enable / disable discovery message transmission / monitoring. If discovery message transmission / monitoring is enabled, the sidelink relay and / or WTRU may use measurements from discovery messages.

[0378] The frequency of transmissions during a certain period of time.

[0379] As an example, the sidelink relay and / or the WTRU may determine which of the sidelink measurements (e.g., Tx SL measurements and / or Rx SL measurements) to use based on the number of transmissions transmitted from and / or received by it in a certain time period. The sidelink relay and / or the WTRU may use the sidelink measurements (e.g., Tx SL measurements and / or Rx SL measurements) for the direction corresponding to the most frequent transmissions. The sidelink relay and / or the WTRU may determine which of the sidelink measurements (e.g., Tx SL measurements and / or Rx SL measurements) to use, for example, based on whether the number of transmissions transmitted in a certain time period is greater than the number of receptions in the same time period (and / or vice versa).

[0380] As an example, the sidelink relay and / or WTRU may use a Tx SL measurement value (e.g., a Tx-RSRP measurement value) if the number of transmissions transmitted by it within a certain window meets (e.g., is greater than or equal to) a threshold and / or if the number of transmissions received by it within the window fails to meet (e.g., is less than) a threshold.

[0381] As an example, the sidelink relay and / or WTRU may use an Rx SL measurement value (e.g., an Rx-RSRP measurement value) if the number of transmissions received by it within a certain window meets (e.g., is greater than or equal to) a threshold and / or if the number of transmissions transmitted by it within the window fails to meet (e.g., is less than) a threshold.

[0382] As an example, a sidelink relay and / or WTRU may use a Tx SL measurement value (e.g., a Tx-RSRP measurement value) if the number of transmissions transmitted by it within a certain window meets (e.g., is greater than or equal to) a threshold, and otherwise use an Rx SL measurement value.

[0383] As an example, a sidelink relay and / or WTRU may use an Rx SL measurement value (e.g., an Rx-RSRP measurement value) if the number of transmissions received by it within a certain window meets (e.g., is greater than or equal to) a threshold, and otherwise use a Tx SL measurement value.

[0384] As an example, if the transmission / reception is periodic, the sidelink relay and / or WTRU may use sidelink measurement values ​​of data transmission (e.g., Tx SL measurement values ​​of data transmission, Rx SL measurement values ​​of data transmission, or a combination of Tx SL measurement values ​​and Rx SL measurement values ​​of data transmission), otherwise the sidelink discovery transmission measurement values ​​(e.g., SD-RSRP measurement values) may be used.

[0385] As an example, depending on which of the two types of transmissions occurs more frequently, the sidelink relay and / or the WTRU may use sidelink measurement values ​​of data transmission (e.g., Tx SL measurement values ​​of data transmission, Rx SL measurement values ​​of data transmission, or a combination of Tx SL measurement values ​​and Rx SL measurement values ​​of data transmission) or sidelink discovery transmission measurement values ​​(e.g., SD-RSRP measurement values).

[0386] In various embodiments, relay (re)selection may depend on which of the one or more sidelink measurement values ​​are available and / or measured. In various embodiments, the WTRU and / or the sidelink relay may trigger relay (re)selection using different rules and / or based on which of the one or more sidelink measurement values ​​are available and / or measured and / or based on which of the one or more sidelink measurement values ​​are used. For example, when the sidelink measurement value (as determined herein) meets (e.g., is below) a threshold, the WTRU and / or the sidelink relay may trigger reselection. The WTRU and / or the sidelink relay may be configured with different thresholds for each type of sidelink measurement value.

[0387] The WTRU and / or the sidelink relay may be configured with rules for triggering (re)selection based on a sidelink measurement value of a data transmission (e.g., a Tx SL measurement value of a data transmission, an Rx SL measurement value of a data transmission, or a combination of a Tx SL measurement value and an Rx SL measurement value of a data transmission) and a sidelink discovery transmission measurement value (e.g., an SD-RSRP measurement value). For example, when the sidelink measurement value of the data transmission meets (e.g., is below) a threshold and the sidelink discovery transmission measurement value (e.g., of a potential / candidate sidelink relay) is above a threshold, the WTRU and / or the sidelink relay may trigger (re)selection. The WTRU and / or the sidelink relay may be (pre-)configured with specific measurement values ​​(e.g., sidelink measurement values ​​of data transmission and / or sidelink discovery transmission measurement values) for triggering a (re)selection decision.

[0388] In various embodiments, the WTRU and / or sidelink relay may consider measurements of other sidelink relays and / or base stations (e.g., gNBs) as part of or in conjunction with a (re)selection decision. How such measurements may be considered may depend on which of the one or more sidelink measurements are available and / or measured. For example, if a sidelink measurement of a data transmission of a current sidelink relay (e.g., any of a Tx SL measurement of a data transmission, an Rx SL measurement of a data transmission, and a combination of a Tx SL measurement and an Rx SL measurement of a data transmission) is available / considered (as described herein), then the WTRU and / or sidelink relay may trigger reselection if the sidelink measurement of the data transmission of the current sidelink relay fails to meet (e.g., is below) a threshold and the sidelink discovery transmission measurement of an alternative / potential / candidate sidelink relay (e.g., an SD-RSRP measurement) meets (is above) another threshold. As another example, if the sidelink discovery transmission measurement value (e.g., SD-RSRP measurement value) of the current sidelink relay is available and / or considered (as described herein), the WTRU and / or sidelink relay may trigger (re)selection when the sidelink discovery transmission measurement value (e.g., SD-RSRP measurement value) of an alternative / potential / candidate sidelink relay may be a threshold amount higher than the sidelink discovery transmission measurement value (e.g., SD-RSRP measurement value) of the current sidelink relay.

[0389] For example, the reselection decision may take into account the transmit power of the sidelink data transmission when the transmit power of the sidelink data transmission may change.

[0390] In various embodiments, the WTRU may transmit a power level indication when the PC5-RRC is connected to a peer WTRU. The WTRU may transmit such a power level indication when it operates as a sidelink relay for the PC5-RRC connection. For example, if the reselection decision is based on a sidelink measurement of a data transmission (e.g., based only on a sidelink measurement of a data transmission), the WTRU may transmit a power level indication. The WTRU may use one or more of various protocols (including a PC5-RRC protocol, a MAC-CE protocol, or an SCI protocol) to transmit a transmission including information indicating a power level indication (or an indication of a change in power level). For example, a WTRU operating as a sidelink relay may transmit a transmission including information indicating an index corresponding to a power level range indicated by a MAC CE. For example, a WTRU operating as a sidelink relay may transmit the transmission when the power level range indicated by the MAC CE changes from one power level range to another power level range. A WTRU receiving such an indication may use the indication to update and / or bias a reselection decision. In various embodiments, the reselection threshold used for the reselection decision may be a function of the indication.In various embodiments, the WTRU may be configured with different thresholds for each power level indication value and / or power level range.

[0391] In various embodiments, a WTRU (e.g., a remote WTRU) may determine a reselection decision based on a combination of sidelink measurements (e.g., Tx SL measurements, Rx SL measurements, or a combination of Tx SL measurements and Rx SL measurements) from a peer WTRU (e.g., a sidelink relay) and a transmit power of a sidelink transmission performed by the WTRU. In various embodiments, the WTRU may use different reselection thresholds depending on the transmit power used for transmissions to the same sidelink relay. In various embodiments, the WTRU may determine, bias, and / or update one or more (e.g., configured) reselection thresholds based on the transmit power used for transmissions to the same sidelink relay. The WTRU may determine, bias, and / or update any of the reselection thresholds using a value that is a function of the transmit power.

[0392] In various embodiments, the WTRU may determine to enable and / or disable reporting / forwarding of sidelink measurements ("SL-measurement reporting"). The WTRU may enable and / or disable SL-measurement reporting based on the determination. The WTRU may determine and / or may, for example, enable and / or disable SL-measurement reporting for various links. The various links may include one or more unicast links. The WTRU may determine and / or may enable and / or disable SL-measurement reporting based on the presence of discovery.

[0393] Examples of SL-measurement value reporting may include aperiodic SL-measurement value reporting and periodic SL-measurement value reporting. In various implementations, the periodicity of SL-measurement value reporting may be determined based on the QoS of the relay service.

[0394] The decision whether to enable, disable and / or perform SL-measurement reporting (and / or which type of SL-measurement reporting to perform) may be based on any of the following:

[0395] (Pre)Configuration.

[0396] As an example, the WTRU may be (pre-)configured per resource pool and / or per unicast link as to whether SL-measurement reporting is to be enabled and / or disabled. The WTRU may transmit one or more transmissions including information indicating such configuration to a peer WTRU. The WTRU may transmit these transmissions using one or more of various protocols including an RRC protocol such as the PC5 RRC protocol.

[0397] Availability and / or receipt of messages (eg, DIRECT_COMM_REQ messages) from peer WTRUs.

[0398] In various embodiments, if the WTRU does not receive a discovery message within a certain time period (e.g., a (pre-)configured time window), the WTRU may enable SL-measurement reporting (and / or its configuration). In various embodiments, the time period may be (pre-)configured per service and / or per resource pool. In various embodiments, the time period may be a function of the CBR of the resource pool.

[0399] In various embodiments, the WTRU may enable SL-measurement reporting if discovery (e.g., transmission and / or reception of discovery transmissions therefrom) is suppressed, disabled, etc. In various embodiments, the WTRU may disable SL-measurement reporting if discovery (e.g., transmission and / or reception of discovery transmissions therefrom) is not suppressed, enabled, etc.

[0400] A model is discovered (eg, Model A or Model B Discovered).

[0401] For example, the sidelink relay may enable SL-measurement reporting if discovery is using Model A. Alternatively, the sidelink relay may disable SL-measurement reporting if discovery is using Model B. The remote WTRU may enable SL-measurement reporting if discovery is using Model B, and may disable SL-measurement reporting if discovery is using Model A.

[0402] Representative load determination and load reporting / indication

[0403] A WTRU (e.g., a sidelink relay) may determine its load based on any of the following:

[0404] Buffer information of the WTRU.

[0405] In various embodiments, the WTRU may determine its load based on the amount of data (or occupancy thereof) in one or more buffers of the WTRU.

[0406] In various embodiments, the WTRU may determine its load based on the amount of data associated with one or more SLRBs and / or one or more LCHs (and / or one or more logical channel groups (LCGs)). As an example, the WTRU may determine its load based on the amount of data associated with the SLRB having (e.g., assigned) the highest priority. As another example, the WTRU may determine its load based on the amount of data associated with a particular or any SLRB (such as the maximum amount of data associated with a particular or any SLRB). As another example, the WTRU may determine its load based on the total amount of data associated with all SLRBs. As another example, the WTRU may determine its load based on the amount of data associated with the LCH (and / or LCG) having (e.g., assigned) the highest priority. As another example, the WTRU may determine its load based on the amount of data associated with a particular or any LCH (and / or LCG) (such as the maximum amount of data associated with a particular or any LCH (and / or LCG)). As another example, the WTRU may determine its load based on the total amount of data associated with all LCHs (and / or LCGs).

[0407] In various embodiments, the WTRU may determine the load (e.g., as disclosed herein) taking into account (e.g., only taking into account) SLRBs and / or LCHs configured for relay and / or for use in conjunction with relay. In various embodiments, the WTRU may determine (e.g., measure) the amount of data in the buffer (or its occupancy). The buffer may include any of a buffer associated with Uu (e.g., a radio link control (RLC) protocol buffer) and a buffer associated with a SL RLC protocol channel configured for relay and / or for use in conjunction with relay.

[0408]

[0046] Above and herein, the term "SLRB" may refer to any of a sidelink radio bearer and a SL RLC protocol channel associated with an end-to-end bearer (Sidelink for Uu).

[0409] The number of currently active links of the WTRU and / or the number of connected WTRUs (which may include one or more WTRUs associated with a relay (e.g., only a relay)), etc.

[0410] CR of WTRU.

[0411] In various embodiments, the WTRU may determine its load as a measured CR on the sidelink or as a function of a measured CR on the sidelink.

[0412] In various embodiments, the WTRU may calculate the CR by taking into account resources used for relaying data, such as resources used only for relaying (e.g., transmitting) data. In various embodiments, the WTRU may calculate a relay-specific CR and determine such CR to be its load. The WTRU may calculate the relay-specific CR based on and / or using resources reserved by the WTRU for relaying data.

[0413] A WTRU (e.g., a source WTRU, a destination WTRU, etc.) may be (pre-)configured with a mapping table for determining load information of a sidelink relay (or another WTRU). A sidelink relay (or other WTRU) may indicate its load information by transmitting one or more transmissions (e.g., one or more discovery message transmissions) including information indicating the load information. The information indicating the load information may be, for example, information indicating corresponding buffer information (e.g., its index). The WTRU may, for example, transmit the transmission using one or more of a variety of protocols, and the information indicating the load information may be carried, for example, in any of a MAC CE and an SLRRC message. In various embodiments, a sidelink relay (or other WTRU) may transmit load information implicitly. For example, a sidelink relay (or other WTRU) may transmit load information using one or more transmissions (e.g., one or more discovery message transmissions) including information implicitly indicating the load information. Information implicitly indicating load information may include any of the following: (i) resources or resource groups (time / frequency) allocated to load values ​​(e.g., specific resources or resource groups (time / frequency) allocated to different load values); (ii) periodicity of transmissions (e.g., discovery message transmissions) associated with load values ​​(e.g., different load values); (iii) transmission power of transmissions (e.g., discovery message transmissions) associated with load values ​​(e.g., different load values); (iv) use of different discovery models (e.g., model A versus model B); and (v) LCH or LCH ID (e.g., different LCH or LCH ID) used for transmissions in these transmissions (e.g., discovery message transmissions), such as where an LCH ID may be associated with a load (range) and / or different LCH IDs may be associated with different loads (ranges).

[0414] A sidelink relay (or other WTRU) may determine different load amounts based on (e.g., in accordance with, as a function of, etc.) any of the following:

[0415] UL and / or DL

[0416] In various embodiments, the sidelink relay (or other WTRU) may calculate or otherwise determine either the UL load and the DL load. The sidelink relay (or other WTRU) may determine the UL load (e.g., using the methods herein) from the traffic and / or one or more links associated with the sidelink relay to the Uu. The sidelink relay (or other WTRU) may determine the DL load from the traffic and / or one or more links associated with the Uu relay to the sidelink.

[0417] Priority and / or QoS

[0418] In various embodiments, a sidelink relay (or other WTRU) may calculate or otherwise determine a plurality of load quantities. Each of the load quantities may be associated with a priority or similar QoS characteristic associated with the data being relayed. In various embodiments, a sidelink relay (or other WTRU) may calculate or otherwise determine a load associated with a subset of RLC channels having similar QoS characteristics (e.g., priority) and / or a number of links having similar priorities and / or services.

[0419] In various embodiments, the remote WTRU may consider different load amounts in conjunction with relay (re)selection. The remote WTRU may consider different load amounts in conjunction with its own service characteristics in conjunction with relay (re)selection. In various embodiments, the remote WTRU may prioritize and / or prioritize UL load or DL ​​load based on (e.g., according to) the configuration of the established end-to-end bearers. In various embodiments, the decision criteria that the remote WTRU may use for (re)selection may be configured such that the DL load may be more important than the UL load (or vice versa). In various embodiments, the remote WTRU may prioritize and / or prioritize UL load or DL ​​load based on (e.g., according to) information configured at the WTRU by the network or upper layers. In various embodiments, the remote UE may consider priority-specific loads that may be similar and / or the same as the priority and / or QoS of the data to be sent / received from the network. In various embodiments, the remote UE may only consider priority-specific loads that may be similar and / or the same as the priority and / or QoS of the data to be sent / received from the network.

[0420] In various embodiments, a WTRU (e.g., a remote WTRU) may select a sidelink relay (e.g., for relay selection) based on the load of the sidelink relay and / or a sidelink measurement of a path including the sidelink relay. In various embodiments, the WTRU may be (pre)configured with a relay load threshold (e.g., a maximum relay load may be selected). The relay load threshold may be (pre)configured based on the QoS of the relay service and / or the CBR of the resource pool. The WTRU may select one of a plurality or a group of sidelink relays based on satisfying a (re)selection criterion including a sidelink measurement associated with the sidelink relay (e.g., the sidelink relay with the highest SL-RSRP measurement) and / or load information of the sidelink relay (e.g., conditions regarding load, such as an allowed load). In various embodiments, the WTRU may be (pre)configured with a minimum sidelink measurement (e.g., a minimum RSRP between itself and the relay) to select the relay. In various embodiments, the minimum sidelink measurement value (e.g., minimum RSRP) may be (pre)configured based on the CBR of the resource pool and / or the QoS of the relay service. The WTRU may select one of a plurality or a group of sidelink relays based on the load. For example, the WTRU may select one of the plurality of sidelink relays based on which sidelink relay has the lowest load among all sidelink relays that meet the sidelink measurement value criteria. Alternatively, the WTRU may select a group of sidelink relays based on which sidelink relays have the lowest load among all sidelink relays that meet the sidelink measurement value criteria.

[0421] In various embodiments, the WTRU may determine whether to select (e.g., for relay reselection) another one of the plurality or group of sidelink relays based on any of the load of the current relay, the load of the potential / candidate relay, the sidelink measurement associated with the current relay, and / or the sidelink measurement associated with the potential / candidate relay. In various embodiments, the WTRU may be (pre)configured with and may use various criteria in conjunction with performing relay reselection. The various criteria may include and / or be based on any of: (i) a load threshold for the current relay; (ii) a load threshold for the potential relay; (iii) a load offset threshold between the current relay and the potential relay to perform relay reselection; (iv) a sidelink measurement (e.g., SL-RSRP measurement) threshold for the current relay; (v) a sidelink measurement (e.g., SL-RSRP measurement) for the potential relay; and (vi) a sidelink measurement (e.g., SL-RSRP measurement) offset threshold between the current relay and the potential relay.

[0422] If the load condition and / or the sidelink measurement value condition are met, the WTRU may perform relay selection. In various embodiments, if the WTRU detects that another sidelink relay has a load offset from the current sidelink relay that satisfies (e.g., is greater than) an offset threshold and / or a sidelink measurement value (e.g., SL-RSRP measurement value) offset from the current sidelink relay that satisfies (e.g., is greater than) a sidelink measurement value (e.g., SL-RSRP measurement value) offset threshold, the WTRU may select another relay (e.g., for relay reselection).

[0423] Representative recovery process

[0424] In various embodiments, the WTRU may perform a recovery procedure based on and / or by performing any of the following:

[0425] The WTRU may send an inactivity indication to the newly established link.

[0426] In various embodiments, the WTRU may maintain information related to and / or associated with one or more inactive relays to facilitate fast relay (re)selection (e.g., according to a fast relay (re)selection procedure). The WTRU may then send an inactivity indication to a newly established link if it can restore the current relay based on the information related to and / or associated with the one or more inactive relays.

[0427] The WTRU may stop relay reselection by stopping transmission and / or receiving direct communication message (eg, DIRECT_COMM_REQ message) transmissions.

[0428] The WTRU may release the connection to the newly established link, for example, by sending a PC5 RRC Release message.

[0429] If it can perform transmission / reception using the current relay (e.g., recovery from the current relay is possible), the WTRU may perform any of the various implementations of the above process. The WTRU may determine whether it can transmit / receive using the current relay based on any of the following:

[0430] The sidelink measurement of the current relay is better than the threshold; and

[0431] The UE receives the message (eg, DIRECT_COMM_REQ message).

[0432] In various embodiments, the WTRU may perform path (re)selection based on the reception of source data (e.g., reception of one or more transmissions from the source WTRU). The WTRU may switch from the relay path to the direct path if, for example, the WTRU correctly decodes one or more messages from the source WTRU. In various embodiments, the WTRU may monitor direct communication messages from the source WTRU (e.g., DIRECT_COMM_REQ messages) and / or may perform path reselection if, for example, the RSRP associated with the direct communication messages of the source WTRU is greater than a threshold.

[0433] In various embodiments, the WTRU may determine which sidelink measurement value (e.g., which of the sidelink measurement value transmitted by a direct communication message (e.g., a DIRECT_COMM_REQ message) and / or the sidelink measurement value transmitted by a data) to use for determining (e.g., estimating) or in conjunction with a sidelink channel between a sidelink relay and a remote WTRU and / or a sidelink channel between two remote WTRUs. The sidelink measurement value may be determined based on any of the following:

[0434] Configured per service. For example, each relay service may be configured with one or both of the sidelink measurements for direct communication message transmissions, and the sidelink measurements for data transmissions may be configured for each relay service. The WTRU may determine which sidelink measurement to use for determining the sidelink channel or in conjunction with it based on the relay service.

[0435] The CBR of the resource pool. For example, if the CBR of, for example, the data resource pool is greater than a threshold, the WTRU may determine to use and / or use sidelink measurements of direct communication message transmissions to determine the quality of the sidelink channel or in combination therewith. Alternatively, if, for example, the CBR of the data resource pool is less than a threshold, the WTRU may determine to use and / or use sidelink measurements of data communications. The method may be driven to reduce transmissions of the WTRU in the data resource pool when the CBR is higher.

[0436] CR of the WTRU. For example, if, for example, the CR of the WTRU meets (e.g., is greater than or less than) a threshold, the WTRU may use or combine sidelink measurements of data communications to determine the sidelink channel and / or may otherwise use sidelink measurements of direct communication message transmissions.

[0437] The discovery model used in the relay service (Model A, Model B, or a combination of Model A and Model B). For example, the WTRU may use or combine sidelink measurements for direct communication messaging for a relay service of one discovery model (e.g., Model A) to determine the sidelink channel and may use or combine sidelink measurements for data communications for a relay service of a different discovery model (e.g., Model B) to determine the sidelink channel.

[0438] The frequency of transmissions during a certain time period. In various embodiments, if the amount of data transmission in one direction (Tx or Rx) and / or both directions (Tx and Rx) meets (e.g., is greater than) a threshold, the WTRU may use a sidelink measurement of data transmission (e.g., a Tx SL measurement of data transmission, an Rx SL measurement of data transmission, or a combination of a Tx SL measurement of data transmission and an Rx SL measurement of data transmission), otherwise a sidelink discovery transmission measurement (e.g., an SD-RSRP measurement) may be used.

[0439] In various embodiments, the WTRU may be informed by another WTRU which of the sidelink measurement values ​​(e.g., sidelink measurement values ​​transmitted by a direct communication message (e.g., a DIRECT_COMM_REQ message) and / or which of the sidelink measurement values ​​transmitted by a data) to use for relay service. In various embodiments, another WTRU may use one or more direct communication messages (e.g., including an indication thereof in a direct communication message) to inform the WTRU which of the sidelink measurement values ​​to use for relay service. Alternatively, another WTRU may inform the WTRU which of the sidelink measurement values ​​to use for PC5 RRC messages (e.g., when the WTRU has an established PC5 RRC connection). Alternatively, another WTRU may inform the WTRU which of the sidelink measurement values ​​to use during the link establishment process.

[0440] A WTRU (e.g., a sidelink relay or a remote WTRU) may start / stop monitoring a discovery resource pool after receiving an indication from a peer WTRU as to which of the sidelink measurements to use. In various embodiments, the WTRU may stop monitoring the discovery resource pool if, for example, the WTRU receives an indication (e.g., in a PC5 RRC message) to use or combine the sidelink measurements of data communications to determine the sidelink channel. Alternatively, the WTRU may start monitoring the discovery resource pool if, for example, the WTRU receives an indication to use or combine the sidelink measurements in the discovery resource pool to determine the sidelink channel.

[0441] Representative methods for supporting unicast / multicast-based relay communications

[0442] In various embodiments, the WTRU may prioritize one sidelink relay over other sidelink relays if, for example, the sidelink relay is in the same group as the remote WTRU (source WTRU and / or destination WTRU). The group information may be implicitly / explicitly included in the direct communication message (e.g., DIRECT_COMM_REQ message). In various embodiments, the WTRU may prioritize sidelink relays in the same group if, for example, the sidelink measurement value of the direct communication message is greater than a threshold. In various embodiments, the WTRU may further prioritize the sidelink relays in the group based on the WTRU ID and / or the sidelink relay ID. For example, the WTRU may prioritize a WTRU that is a group leader of the group in the form of a sidelink relay. Alternatively, the WTRU may prioritize a specific WTRU ID in the group based on its ID.

[0443] In various embodiments, the WTRU may (pre)determine one or more WTRUs as candidates for sidelink relays. The WTRU may indicate the WTRU ID and / or group ID of the candidate WTRUs in a direct communication message (e.g., a DIRECT_COMM_REQ message) to request one or more WTRUs to become sidelink relays. For example, in a convoy scheduling scenario, the WTRUs may be indexed according to their order in the convoy. WTRU4 may wish to communicate with the leader (e.g., WTRU1) via a sidelink relay. WTRU4 may indicate WTRU2 and WTRU3 as candidates for sidelink relays in a direct communication message. Alternatively, WTRU4 may indicate a group ID of a group of candidate WTRUs, any of which within the group may become a sidelink relay for WTRU4.

[0444] In various embodiments, the sidelink relay may determine whether to forward a message (e.g., a DIRECT_COMM_REQ message) based on any of the following (possibly for multicast / broadcast based relay services):

[0445] RSRP associated with the message. For example, the sidelink relay may forward the message (eg, DIRECT_COMM_REQ message) if, for example, the RSRP associated with the message is greater than a threshold and / or less than another threshold.

[0446] Distance between source and relay WTRUs. For example, the sidelink relay may forward a message (eg, a DIRECT_COMM_REQ message) if the distance between the sidelink relay and the remote WTRU is greater than a threshold and / or less than another threshold.

[0447] Figure 6600 for performing path selection or path reselection. The process 600 and the accompanying disclosure herein may be considered to be at least Figures 3 to 5 The accompanying disclosure is a summary of the disclosure and is considered to cover and / or include various embodiments of the above disclosure, including, for example, Figures 3 to 5 The accompanying disclosure. You can use Figures 1 to Figure 2 The process 600 may be performed using the architecture of the communication system 100. Other architectures may also be used to perform the process 600.

[0448] See also Figure 6 , a first WTRU (e.g., a source WTRU) may determine one or more first measurements based on one or more first sidelink transmissions received from a second WTRU (e.g., a first sidelink relay) (602). The first WTRU may receive one or more second measurements associated with a path between the first WTRU and a third WTRU (e.g., a destination WTRU) and including the second WTRU from the second WTRU (604). The second measurements may be based at least in part on one or more second sidelink transmissions exchanged between the third WTRU and the second WTRU. Alternatively, the second measurements may be based at least in part on one or more second sidelink transmissions exchanged between the third WTRU and a fourth WTRU (e.g., a second sidelink relay).

[0449] The first WTRU may determine a measurement value of a path ("path measurement value") based on at least one of the first measurement value and at least one of the second measurement value (606). The first WTRU may determine one or more transmission parameters for transmitting one or more discovery messages during a communication period based on either of the path measurement value and a QoS criterion (608). The WTRU may transmit the discovery message according to the transmission parameters. (610).

[0450] Although not shown, the first WTRU may make a determination to transmit a discovery message based on either of a QoS criterion and a path measurement value, for example, before determining the transmission parameters. In various embodiments, the first WTRU may make a determination not to transmit a discovery message based on either of a QoS criterion and a path measurement value, for example, before determining the transmission parameters, and may forgo determining the transmission parameters and transmitting the discovery message according to the transmission parameters. In various embodiments, the WTRU may trigger the transmission of a discovery message based on the QoS and the path measurement value and may transmit the discovery message while still being triggered.

[0451] In various embodiments, the transmission parameters may include any of: transmission power, number of (re)transmissions, and periodicity of transmissions for discovery messages. In various embodiments, the WTRU may determine the path measurement value as a function (metric) of at least one of (i) the first measurement value or (ii) the second measurement value or (iii) the first measurement value and at least one of the second measurement value. In various embodiments, the function may be any of the minimum RSRP and the maximum RSRP.

[0452] In various embodiments, the path measurement value may include one or more metrics of (i) the first measurement value or (ii) the second measurement value or (iii) at least one of the first measurement value and at least one of the second measurement value. In various embodiments, these metrics may include any of the minimum RSRP and the maximum RSRP.

[0453] In various embodiments, the second measurement value may include any of the following: a channel quality indicator (CQI), a reference signal received power (RSRP), a reference signal received quality (RSRQ), a path gain, a path loss, a distance between the first WTRU and the second WTRU, a distance between the second WTRU and the third WTRU, a reachability indicator, a channel busy rate (CBR) of the resource pool, and a channel occupancy rate (CR) of the second WTRU. In various embodiments, the first measurement value may include any of the following: a channel quality indicator (CQI), a reference signal received power (RSRP), a reference signal received quality (RSRQ), a path gain, a path loss, a distance between the first WTRU and the second WTRU, a channel busy rate (CBR) of the resource pool, and a channel occupancy rate (CR) of the first sidelink relay.

[0454] In various embodiments, the second measurement value may be based at least in part on (further based on) one or more third sidelink transmissions transmitted by the first WTRU. In various embodiments, the second measurement value may be based at least in part on (further based on) one or more fourth sidelink transmissions exchanged between the second WTRU and the fourth WTRU. In various embodiments, the second measurement value may be based at least in part on (further based on) one or more fourth sidelink transmissions exchanged between the fifth WTRU and the fourth WTRU and one or more fifth sidelink transmissions exchanged between the second WTRU and the fifth WTRU.

[0455] In various embodiments, a path between a first WTRU and a third WTRU and including a second WTRU may be a first path. And although not shown, the first WTRU may receive a sixth sidelink transmission including a discovery message from a sixth WTRU, wherein the discovery message may include one or more third measurement values ​​associated with a second path between the first WTRU and the third WTRU and including the sixth WTRU. The third measurement value may be based at least in part on one or more seventh sidelink transmissions exchanged between the third WTRU and the sixth WTRU. The first WTRU determines one or more fourth measurement values ​​based on the sixth sidelink transmission. The first WTRU may determine a path measurement value for the second path based on at least one of the third measurement values ​​and at least one of the fourth measurement values. The first WTRU may perform selection of the sixth WTRU based at least in part on the path measurement value for the second path.

[0456] In various embodiments, the first WTRU may perform selection of the sixth WTRU based at least in part on the path measurement value of the second path and one or more criteria. In various embodiments, the one or more criteria include any of the following: (i) received signal strength of the message; (ii) distance between the first WTRU and the second WTRU; (iii) distance between the first WTRU and the third WTRU; (iv) QoS criteria; (v) location of the first WTRU; (vi) location of the second WTRU; (vii) location of the third WTRU; (viii) CBR of the resource pool; (ix) CR of the first WTRU; (x) speed of the second WTRU; (xi) speed of the third WTRU; (xii) number of relay links; (xiii) number of SLRBs currently established at the second WTRU; and (xiv) previous reception of other relevant messages associated with the reselection event.

[0457] In various embodiments, the first WTRU may receive information indicating one or more metrics of one or more of the second measurement values ​​associated with the first path. The first WTRU may determine a path measurement value for the first path based on the one or more metrics of the first measurement value and the second measurement value and / or one or more of the second measurement values. In various embodiments, these metrics may include any of a minimum RSRP and a maximum RSRP.

[0458] Figure 7 is a flow chart showing an exemplary process 700 for performing measurement value reporting. The process 700 and the accompanying disclosure herein may be considered to be at least Figures 3 to 5 The accompanying disclosure is a summary of the disclosure and is considered to cover and / or include various embodiments of the above disclosure, including, for example, Figures 3 to 5 The accompanying disclosure. You can use Figures 1 to Figure 2The process 700 may be performed using the architecture of the communication system 100. Other architectures may also be used to perform the process 700.

[0459] See also Figure 7 , a first WTRU (e.g., a sidelink relay) may receive one or more first measurements associated with a path between a second WTRU (e.g., a source (destination) WTRU) and a third WTRU (e.g., a destination (source) WTRU) and including the first WTRU (702). The first measurements may be based at least in part on at least one of: (i) one or more first sidelink transmissions received from the second WTRU, (ii) one or more second sidelink transmissions transmitted from the first WTRU to the third WTRU or to a fourth WTRU (e.g., another sidelink relay), and (iii) one or more third sidelink transmissions exchanged between the third WTRU and the fourth WTRU or between the third WTRU and the fifth WTRU (another sidelink relay).

[0460] The first WTRU may determine one or more second measurements based on one or more fourth sidelink transmissions received from a third WTRU or a fourth WTRU (704). The first WTRU may determine triggering reporting of one or more of the first measurement value and the second measurement value based on (i) QoS (e.g., of the relay service), (ii) a channel busy rate (CBR) of a resource pool (e.g., configured for sidelink transmissions), and (iii) one or more metrics of the one or more first measurement values ​​or the one or more second measurement values ​​or at least one of the one or more first measurement values ​​and at least one of the one or more second measurement values ​​(706). The first WTRU may transmit one or more of the first measurement value and the second measurement value to the second WTRU (708). The first WTRU may, for example, transmit one or more sidelink transmissions including one or more of the first measurement value and the second measurement value.

[0461] In various embodiments, the first WTRU may receive information indicating that a direct communication message from a second WTRU is forthcoming. In various embodiments, the information may be sidelink control information (SCI) associated with the direct communication message or may be received in the SCI. In various embodiments, the direct communication message may include a relay request.

[0462] Figure 8 800 for performing relay selection or reselection. The process 800 and the accompanying disclosure herein may be considered to be at least Figures 3 to 5 The accompanying disclosure is a summary of the disclosure and is considered to cover and / or include various embodiments of the above disclosure, including, for example, Figures 3 to 5The accompanying disclosure. You can use Figures 1 to Figure 2 The process 800 may be performed using the architecture of the communication system 100. Other architectures may also be used to perform the process 800.

[0463] See also Figure 8 , a first WTRU (e.g., a source (destination) WTRU) may obtain one or more measurements for each of one or more other WTRUs (e.g., sidelink relays) (802). The one or more measurements for each of the other WTRUs may be based at least in part on one or more sidelink transmissions exchanged between the first WTRU and the corresponding other WTRU. The first WTRU may perform reselection between the one or more other WTRUs based at least in part on the one or more measurements of the one or more other WTRUs (804).

[0464] In various embodiments, the first WTRU may reselect among other WTRUs based at least in part on the measured values ​​and QoS criteria (e.g., of the service). In various embodiments, the first WTRU may reselect among the one or more other WTRUs based at least in part on the one or more measured values ​​and the number of hops per path of one or more of the plurality of paths associated with the one or more other WTRUs. In various embodiments, the first WTRU may reselect among other WTRUs based at least in part on any of the one or more measured values ​​and QoS criteria (e.g., of the service) and the number of hops per path of one or more of the plurality of paths associated with the one or more other WTRUs. In various embodiments, the first WTRU may reselect among other WTRUs based at least in part on the one or more measured values ​​and load information of any of the other WTRUs and the first WTRU. In various embodiments, the first WTRU may reselect among other WTRUs based at least in part on the one or more measured values ​​and load information of any of the other WTRUs, the first WTRU, and the network element.

[0465] In various embodiments, the first WTRU may determine at least some of the one or more measurements. In various embodiments, the first WTRU may determine measurements for each of a plurality of paths associated with the one or more other WTRUs. In various embodiments, the first WTRU may determine measurements for each of the plurality of paths based on one or more measurements of one or more sidelink transmissions occurring over some or all hops of such paths.

[0466] In various embodiments, the measurement value of at least one of the multiple paths may be any of: a SL-RSRP measurement value of a hop segment of the at least one of the multiple paths and an accumulated SL-RSRP of the hop segments of the at least one of the multiple paths. In various embodiments, the measurement value of at least one of the multiple paths is a combination of SL-RSRP measurement values ​​of multiple hop segments of the at least one of the multiple paths. In various embodiments, the measurement value of at least one hop segment of at least one of the multiple paths may include any of: a measurement value of a sidelink transmission received by the WTRU, an accumulation or other combination of measurement values ​​of sidelink transmissions received by the WTRU, one or more reported measurement values ​​of a transmission, and a reported accumulation or other combination of measurement values ​​of sidelink transmissions.

[0467] In various embodiments, the first WTRU may determine a measurement of at least one hop of at least one of the multiple paths. In various embodiments, the first WTRU may determine a measurement of one or more sidelink transmissions occurring on at least one hop of at least one of the multiple paths. In various embodiments, the first WTRU may determine the measurement using any of and / or as a function of any of: measurements of sidelink transmissions received by the WTRU, an accumulation or other combined measurements of sidelink transmissions received by the WTRU, reported measurements of sidelink transmissions, and a reported accumulation or other combination of measurements of sidelink transmissions. In various embodiments, the first WTRU may determine the measurement using any of and / or as a function of any of: measurements of sidelink data transmissions and measurements of direct communication message transmissions. In various embodiments, the first WTRU may determine the measurement using any of and / or as a function of any of: measurements of sidelink data transmissions and measurements of sidelink discovery message transmissions.

[0468] Fig. 9 900 for performing message forwarding. The process 900 and the accompanying disclosure herein may be considered to be at least Figures 3 to 5 The accompanying disclosure is a summary of the disclosure and is considered to cover and / or include various embodiments of the above disclosure, including, for example, Figures 3 to 5 The accompanying disclosure. You can use Figures 1 to Figure 2 The process 900 may be performed using the architecture of the communication system 100. Other architectures may also be used to perform the process 900.

[0469] See also Figure 8, a first WTRU (e.g., a sidelink relay) may receive a first sidelink transmission including a message from a second WTRU (e.g., a source WTRU, a destination WTRU, or another sidelink relay) (902). The first WTRU may determine a measurement value of the first sidelink transmission (904). The first WTRU may determine to forward the message based on one or more criteria (including the measurement value of the first sidelink transmission) (906). The first WTRU may transmit a second sidelink transmission including the message and the measurement value of the first sidelink transmission (908). In various embodiments, the message may be a direct communication message. In various embodiments, the criteria may include any of the following: (i) the received signal strength of the message; (ii) the distance between the first WTRU and the second WTRU; (iii) the distance between the first WTRU and the third WTRU; (iv) QoS criteria; (v) the location of the first WTRU; (vi) the location of the second WTRU; (vii) the location of the third WTRU; (viii) the CBR of the resource pool; (ix) the CR of the first WTRU; (x) the speed of the second WTRU; (xi) the speed of the third WTRU; (xii) the number of relay links; (xiii) the number of SLRBs currently established at the second WTRU; and (xiv) previous reception of other relevant messages associated with the reselection event.

[0470] in conclusion

[0471] Although features and elements are provided above in specific combinations, it will be understood by those of ordinary skill in the art that each feature or element may be used alone or in any combination with other features and elements. The present disclosure is not limited to the specific embodiments described in this patent application, which are intended to be examples of various aspects. Many modifications and variations can be made without departing from the essence and scope of the present invention, as they will be obvious to those skilled in the art. Unless explicitly provided as such, any element, action or description used in the present application specification should not be understood as being essential or necessary to the present invention. According to the foregoing description, in addition to those listed herein, functionally equivalent methods and devices within the scope of the present disclosure will be obvious to those skilled in the art. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is limited only to the terms of the appended claims and the full range of equivalent forms of such entitled claims. It should be understood that the present disclosure is not limited to a specific method or system.

[0472] For simplicity, the foregoing embodiments are discussed with respect to terminology and structure of infrared capable devices (i.e., infrared transmitters and receivers). However, the embodiments discussed are not limited to these systems, but may be applied to other systems using other forms of electromagnetic waves or non-electromagnetic waves (such as sound waves).

[0473] It should also be understood that the terms used herein are for the purpose of describing specific embodiments only and are not intended to be limiting. As used herein, the term "video" or the term "image" may mean any of a snapshot, a single image, and / or a plurality of images displayed on a temporal basis. As another example, when referred to herein, the term "user equipment" and its abbreviation "UE", the term "remote" and / or the term "head mounted display" or its abbreviation "HMD" may mean or include (i) a wireless transmit and / or receive unit (WTRU); (ii) any of a plurality of embodiments of a WTRU; (iii) a device having wireless functionality and / or having wired functionality (e.g., tetherable) configured with (in particular) some or all of the structure and functionality of a WTRU; (iii) a wireless capable and / or wired capable device configured with less than all of the structure and functionality of a WTRU; or (iv), etc. The following descriptions with respect to the attached Figures 1A-1D As another example, various disclosed embodiments herein are described above and below as utilizing a head mounted display. Those skilled in the art will recognize that devices other than head mounted displays may be utilized, and some or all of the present disclosure and various disclosed embodiments may be modified accordingly without undue experimentation. Examples of such other devices may include drones or other devices configured to stream information to provide an adapted reality experience.

[0474] In addition, the methods provided herein may be implemented in a computer program, software, or firmware incorporated into a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted via a wired or wireless connection) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media (such as built-in hard disks and removable disks), magneto-optical media, and optical media (such as CD-ROM disks and digital versatile disks (DVDs)). A processor associated with the software may be used to implement a radio frequency transceiver for a WTRU, UE, terminal, base station, RNC, or any host computer.

[0475] Variations of the methods, devices, and systems provided above are possible without departing from the scope of the present invention. In view of the various embodiments that may be applied, it should be understood that the illustrated embodiments are merely examples and should not be considered to limit the scope of the following claims. For example, the embodiments provided herein include handheld devices that may include or be used with any suitable voltage source (such as a battery, etc.) that provides any suitable voltage.

[0476] In addition, in the embodiments provided above, processing platforms, computing systems, controllers and other devices comprising processors are indicated. These devices may include at least one central processing unit ("CPU") and memory. According to the practice of those skilled in the art of computer programming, references to the symbolic representations of actions and operations or instructions may be performed by various CPUs and memories. Such actions and operations or instructions may be considered to be "executed", "computer executed" or "CPU executed".

[0477] Those of ordinary skill in the art will appreciate that the actions and symbolic representations of operations or instructions include manipulation of electrical signals by the CPU. The electrical system represents data bits, which may result in the ultimate transformation of electrical signals or reduction of electrical signals and the retention of data bits at memory locations in the memory system, thereby reconfiguring or otherwise changing the operation of the CPU and performing other processing of signals. The memory location that holds the data bits is a physical location that has specific electrical, magnetic, optical, or organic properties that correspond to or represent the data bits. It should be understood that the embodiments are not limited to the above-mentioned platforms or CPUs, and other platforms and CPUs may also support the provided methods.

[0478] The data bits may also be maintained on computer-readable media, including magnetic disks, optical disks, and any other volatile (e.g., random access memory ("RAM")) or non-volatile (e.g., read-only memory ("ROM")) mass storage system readable by the CPU. The computer-readable media may include cooperating or interconnected computer-readable media that reside solely on the processing system or distributed across multiple interconnected processing systems that may be local or remote relative to the processing system. It should be understood that the embodiments are not limited to the above-mentioned memories, and other platforms and memories may also support the provided methods.

[0479] In an exemplary embodiment, any of the operations, processes, etc. described herein may be implemented as computer-readable instructions stored on a computer-readable medium. The computer-readable instructions may be executed by a processor of a mobile unit, a network element, and / or any other computing device.

[0480] There is little difference between hardware implementation and software implementation of various aspects of the system. The use of hardware or software is usually (but not always, because in some contexts, the choice between hardware and software may become important) a design choice that represents a trade-off between cost and efficiency. There may be various media (e.g., hardware, software, and / or firmware) that can implement the processes and / or systems and / or other technologies described herein, and the preferred media may vary with the context of the deployment process and / or system and / or other technologies. For example, if the implementer determines that speed and accuracy are most important, the implementer may choose a media that is primarily hardware and / or firmware. If flexibility is most important, the implementer may choose a specific implementation that is primarily software. Alternatively, the implementer may choose some combination of hardware, software, and / or firmware.

[0481] The above detailed description has listed various embodiments of the device and / or process by using block diagrams, flow charts and / or examples. In the case where such block diagrams, flow charts and / or examples include one or more functions and / or operations, it should be understood by those skilled in the art that each function and / or operation within such block diagrams, flow charts or examples can be implemented individually and / or collectively by a wide range of hardware, software, firmware or almost any combination thereof. In an embodiment, several parts of the subject matter described herein can be implemented via application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), digital signal processors (DSPs) and / or other integrated formats. However, those skilled in the art will recognize that some aspects of the embodiments disclosed herein can be equivalently implemented in integrated circuits as a whole or in part as one or more computer programs running on one or more computers (e.g., one or more programs running on one or more computer systems), one or more programs running on one or more processors (e.g., one or more programs running on one or more microprocessors), firmware or almost any combination thereof, and according to the present disclosure, designing circuits and / or writing software and / or firmware codes will be completely within the technical scope of those skilled in the art. In addition, those skilled in the art will appreciate that the mechanisms of the subject matter described herein can be distributed as a program product in a variety of forms, and that the exemplary embodiments of the subject matter described herein apply regardless of the specific type of signal-bearing medium used to actually perform the distribution. Examples of signal-bearing media include, but are not limited to, the following: recordable type media (such as floppy disks, hard drives, CDs, DVDs, digital tapes, computer memory, etc.); and transmission type media (such as digital and / or analog communication media (e.g., fiber optic cables, waveguides, wired communication links, wireless communication links, etc.)).

[0482] Those skilled in the art will recognize that it is common in the art to describe devices and / or processes in the manner set forth herein, and thereafter use engineering practices to integrate such described devices and / or processes into a data processing system. That is, at least a portion of the devices and / or processes described herein can be integrated into a data processing system via a reasonable amount of experimentation. Those skilled in the art will recognize that a typical data processing system generally may include one or more of the following: a system unit housing; a video display device; a memory, such as a volatile memory and a non-volatile memory; a processor, such as a microprocessor and a digital signal processor; a computing entity, such as an operating system, a driver, a graphical user interface, and an application; one or more interactive devices, such as a touch pad or a screen; and / or a control system, including a feedback loop and a control motor (e.g., feedback for sensing position and / or velocity, a control motor for moving and / or adjusting components and / or quantities). A typical data processing system may be implemented using any suitable commercially available components, such as those typically found in data computing / communication and / or network computing / communication systems.

[0483] The subject matter described herein sometimes shows different parts that are contained in different other parts or connected with different other parts.It should be understood that such depicted architectures are only examples, and in fact many other architectures that achieve the same function can be realized.In a conceptual sense, any arrangement of parts that achieve the same function is effectively "associated" so that the desired function can be achieved.Therefore, any two parts that are combined to achieve a specific function in this article can be regarded as "associated" with each other so that the desired function can be achieved, regardless of the architecture or intermediate parts.Similarly, any two parts that are so associated can also be regarded as "operably connected" or "operably coupled" to each other to achieve the desired function, and any two parts that can be so associated can also be regarded as "operably coupleable" to each other to achieve the desired function.Specific examples of operable coupling include but are not limited to parts that can physically cooperate and / or physically interact and / or parts that can wirelessly interact and / or wirelessly interact and / or parts that can logically interact and / or parts that can logically interact.

[0484] With respect to substantially any plural and / or singular terms used herein, those skilled in the art may translate from the plural to the singular and / or from the singular to the plural as appropriate, as appropriate to the context and / or application. For clarity, various singular / plural arrangements may be explicitly listed herein.

[0485] It will be understood by those skilled in the art that, in general, the terms used herein, especially in the appended claims (e.g., the bodies of the appended claims), are generally intended to be "open" terms (e.g., the term "including" should be interpreted as "including but not limited to", the term "having" should be interpreted as "having at least", the term "comprising" should be interpreted as "including but not limited to", etc.). It will also be understood by those skilled in the art that if a specific number of an introduced claim recitation object is intended, such intent will be explicitly stated in the claim, and in the absence of such a recitation object, there is no such intent. For example, where only one item is intended, the term "single" or similar language may be used. To aid understanding, the following appended claims and / or the description herein may contain the use of the introductory phrases "at least one" and "one or more" to introduce claim recitation objects. However, the use of such phrases should not be understood to imply that any particular claim containing such introduced claim recitation object is limited to an embodiment containing only one such recitation object by the indefinite article "a" or "an" to introduce the claim recitation object. This is true even when the same claim includes the introductory phrases "one or more" or "at least one" and an indefinite article such as "a" or "a kind" (e.g., "a" and / or "a kind" should be interpreted as meaning "at least one" or "one or more"). The same applies to the use of definite articles used to introduce claim recitations. In addition, even if a specific number of introduced claim recitations is explicitly recited, one skilled in the art will recognize that such recitation should be interpreted as meaning at least the stated number (e.g., a bare recitation of "two recitations" without other modifiers means at least two recitations, or two or more recitations). In addition, in those instances where a convention similar to "at least one of A, B, and C, etc." is used, generally speaking, the meaning of such construction is that one skilled in the art will understand the convention (e.g., "a system having at least one of A, B, and C" will include, but is not limited to, a system having A alone, B alone, C alone, A and B simultaneously, A and C simultaneously, B and C simultaneously, and / or A, B, and C simultaneously, etc.). In those instances where a convention similar to "at least one of A, B, or C, etc." is used, generally speaking, the meaning of such construction is that one skilled in the art will understand the convention (e.g., "a system having at least one of A, B, or C" will include, but is not limited to, systems having A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). One skilled in the art will also understand that, in fact, any discrete words and / or phrases presenting two or more alternative terms, whether in the specification, claims, or drawings, should be understood to contemplate the possibility of including one of the terms, any of the terms, or both of the terms.For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B." Additionally, as used herein, the term "any of" followed by a listing of multiple items and / or multiple categories of items is intended to include "any of," "any combination," "any multiples," and / or "any combination of multiples" of the items and / or categories of items, either alone or in combination with other items and / or other categories of items. Additionally, as used herein, the term "set" is intended to include any number of items, including zero. Additionally, as used herein, the term "quantity" is intended to include any quantity, including zero.

[0486] In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also described in terms of any individual member or subgroup of members of the Markush group.

[0487] As will be understood by those skilled in the art, for any and all purposes (such as for providing a written description), all ranges disclosed herein also encompass any and all possible subranges and combinations of their subranges. Any listed range can be easily identified as fully describing and enabling the same range to be divided into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be easily divided into a lower third, a middle third, and an upper third, etc. As will be understood by those skilled in the art, all languages ​​such as "up to", "at least", "greater than", "less than", etc. include the cited numbers and refer to ranges that can subsequently be divided into subranges as described above. Finally, as will be understood by those skilled in the art, ranges include each individual number. Thus, for example, a group having 1 to 3 units refers to a group having 1, 2, or 3 units. Similarly, a group having 1 to 5 units refers to a group having 1, 2, 3, 4, or 5 units, etc.

[0488] Furthermore, the claims should not be read as limited to the order or elements presented unless otherwise stated. Additionally, the use of the term "means for..." in any claim is intended to invoke 25 U.S.C. § 112, 6 or means-plus-function claim format, and any claim without the term "means for..." is not intended to be so.

Claims

1. A method implemented in a first wireless transmit / receive unit WTRU, the method comprising: receiving one or more transmissions from a second WTRU, wherein the one or more transmissions include any of one or more data transmissions and one or more discovery transmissions; selecting one or more measured signal characteristics of one of (i) the one or more data transmissions and (ii) the one or more discovery transmissions based on: a priority of at least one of (i) the one or more measured signal characteristics of the one or more data transmissions and (ii) the one or more measured signal characteristics of the one or more discovery transmissions; availability of said one or more measurement signal characteristics for said one or more data transmissions; and whether the first WTRU is currently receiving and is currently scheduled to receive any of one or more data transmissions from the second WTRU; as well as Relay reselection is performed based on a failure of the selected one or more measured signal characteristics to satisfy one or more thresholds.

2. The method according to claim 1, comprising: Information configuring a first resource pool is received, wherein the first resource pool indicates the priority of the measured signal characteristic for data transmission.

3. The method according to at least one of claims 1 to 2, comprising: Information configuring a second resource pool is received, wherein the second resource pool indicates that a measurement signal characteristic used for discovery transmission takes precedence over a measurement signal characteristic used for data transmission.

4. The method according to at least one of claims 1 to 3, comprising: Relay reselection is triggered based on the selected one or more measured signal characteristics failing to satisfy one or more thresholds, wherein performing relay reselection based on the selected one or more measured signal characteristics failing to satisfy one or more thresholds comprises performing relay reselection based on the triggering of relay reselection.

5. A method according to at least one of claims 1 to 4, wherein the selected one or more measurement signal characteristics include (i) one or more reference signal received power measurement values ​​of the one or more data transmissions and (ii) one or more reference signal received power measurement values ​​of the one or more discovery transmissions.

6. A method according to at least one of claims 1 to 5, wherein the selected one or more measurement signal characteristics are the one or more measurement signal characteristics of the one or more data transmissions based on: (i) the priority of the measurement signal characteristics for the data transmission, (ii) the one or more measurement signal characteristics of the data transmission are available, and (iii) the first WTRU is currently receiving and is currently scheduled to receive any of the data transmissions from the second WTRU.

7. A method according to at least one of claims 1 to 5, wherein the selected one or more measurement signal characteristics are the one or more measurement signal characteristics of the one or more data transmissions based on: (i) the priority of the measurement signal characteristics for discovering the transmission, (ii) the one or more measurement signal characteristics of the data transmission are available, and (iii) the first WTRU is currently receiving and is currently scheduled to receive any of the data transmissions from the second WTRU.

8. A method according to at least one of claims 1 to 5, wherein the selected one or more measurement signal characteristics are the one or more measurement signal characteristics of the one or more discovered transmissions based on one or more of the following: (i) the priority of the measurement characteristics of the data transmission, (ii) the one or more measurement signal characteristics of the data transmission are not available, and (iii) the first WTRU is not currently receiving the data transmission from the second WTRU.

9. A method according to at least one of claims 1 to 5, wherein the selected one or more measurement signal characteristics are the one or more measurement signal characteristics of the one or more discovery transmissions based on one or more of the following: (i) a priority of the measurement characteristics of the discovery transmission, (ii) the one or more measurement signal characteristics of the data transmission are not available, and (iii) the first WTRU is not currently receiving the data transmission from the second WTRU.

10. A method according to at least one of claims 1 to 9, wherein the one or more measurement signal characteristics of (i) the one or more data transmissions and (ii) one of the one or more discovery transmissions are selected from any one of one or more first measurement signal characteristics of the one or more data transmissions and one or more second measurement signal characteristics of the one or more discovery transmissions, wherein the one or more first measurement signal characteristics and any one of the one or more second measurement signal characteristics are based on one or more measurement values, and wherein the one or more measurement values ​​include any one of a channel quality indicator, a reference signal received power, a reference signal received quality, a path gain, a path loss, a distance between the first WTRU and the second WTRU, a reachability indicator, a channel busy rate of a resource pool, and a channel occupancy rate of the second WTRU.

11. The method of at least one of claims 1 to 10, wherein the one or more transmissions received from the second WTRU include transmissions received from the third WTRU via a connection between the second WTRU and one of a third WTRU or a base station of a network.

12. A first wireless transmit / receive unit WTRU, the first WTRU comprising a circuit, the circuit comprising a transmitter, a receiver, a processor and a memory, the first WTRU being configured to: receiving one or more transmissions from a second WTRU, wherein the one or more transmissions include any of one or more data transmissions and one or more discovery transmissions; selecting one or more measured signal characteristics of one of (i) the one or more data transmissions and (ii) the one or more discovery transmissions based on: a priority of at least one of (i) the one or more measured signal characteristics of the one or more data transmissions and (ii) the one or more measured signal characteristics of the one or more discovery transmissions; availability of the one or more measurements of the one or more measurement signal characteristics of the one or more data transmissions; as well as whether the first WTRU is currently receiving and is currently scheduled to receive any of one or more data transmissions from the second WTRU; as well as Relay reselection is performed based on a failure of the selected one or more measured signal characteristics to satisfy one or more thresholds.

13. The first WTRU of claim 12, wherein the circuit is configured to: Information configuring a first resource pool is received, wherein the first resource pool indicates the priority of the measured signal characteristic for data transmission.

14. The first WTRU of at least one of claims 12 to 13, wherein the circuit is configured to: Information configuring a second resource pool is received, wherein the second resource pool indicates that a measurement signal characteristic used for discovery transmission takes precedence over a measurement signal characteristic used for data transmission.

15. The first WTRU of at least one of claims 12 to 14, wherein the circuit is configured to: Relay reselection is triggered based on the failure of one or more selected measured signal characteristics to satisfy one or more thresholds, wherein the circuit configured to perform relay reselection based on the failure of one or more selected measured signal characteristics to satisfy one or more thresholds includes the circuit configured to perform relay reselection based on the relay reselection being triggered.

16. A first WTRU according to at least one of claims 12 to 15, wherein the selected one or more measurement signal characteristics include (i) one or more reference signal received power measurement values ​​of the one or more data transmissions and (ii) one of the one or more reference signal received power measurement values ​​of the one or more discovery transmissions.

17. A first WTRU according to at least one of claims 12 to 16, wherein the selected one or more measurement signal characteristics are the one or more measurement signal characteristics of the one or more data transmissions based on: (i) the priority of the measurement signal characteristics for the data transmission, (ii) the one or more measurement signal characteristics of the data transmission are available, and (iii) the first WTRU is currently receiving and is currently scheduled to receive any of the data transmissions from the second WTRU.

18. A first WTRU according to at least one of claims 12 to 16, wherein the one or more measurement signal characteristics selected are the one or more measurement signal characteristics of the one or more data transmissions based on: (i) the priority of the measurement signal characteristics for discovering the transmission, (ii) the one or more measurement signal characteristics of the data transmission are available, and (iii) the first WTRU is currently receiving and is currently scheduled to receive any of the data transmissions from the second WTRU.

19. A first WTRU according to at least one of claims 12 to 16, wherein the selected one or more measurement signal characteristics are the one or more measurement signal characteristics of the one or more discovered transmissions based on one or more of the following: (i) the priority of the measurement characteristics of the data transmission, (ii) the one or more measurement signal characteristics of the data transmission are not available, and (iii) the first WTRU is not currently receiving the data transmission from the second WTRU.

20. A first WTRU according to at least one of claims 12 to 16, wherein the selected one or more measurement signal characteristics are the one or more measurement signal characteristics of the one or more discovery transmissions based on one or more of the following: (i) a priority of the measurement characteristics of the discovery transmissions, (ii) the one or more measurement signal characteristics of the data transmissions are not available, and (iii) the first WTRU is not currently receiving a data transmission from the second WTRU.

21. A first WTRU according to at least one of claims 12 to 20, wherein the one or more measurement signal characteristics of (i) the one or more data transmissions and (ii) one of the one or more discovery transmissions are selected from any one of one or more first measurement signal characteristics of the one or more data transmissions and one or more second measurement signal characteristics of the one or more discovery transmissions, wherein any one of the one or more first measurement signal characteristics and the one or more second measurement signal characteristics are based on one or more measurement values, and wherein any one of the one or more measurement values ​​includes any one of a channel quality indicator, a reference signal received power, a reference signal received quality, a path gain, a path loss, a distance between the first WTRU and the second WTRU, a reachability indicator, a channel busy rate of a resource pool, and a channel occupancy rate of the second WTRU.

22. A first WTRU according to at least one of claims 12 to 21, wherein the one or more transmissions received from the second WTRU include one or more transmissions received from the third WTRU via a connection between the second WTRU and a third WTRU or one of the base stations of the network.

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