Method for efficient paging of user equipment to network relays

Abstract

A method for efficient paging of user equipment to a network relay is described. A wireless transmit / receive unit (WTRU) is provided, the WTRU including a circuit system configured to: establish a connection with a relay WTRU; establish a connection to a network via the relay WTRU; receive an RRC indication of a state change from a first Radio Resource Control (RRC) state to a second RRC state of the WTRU, wherein the first RRC state is different from the second RRC state; change the state from the first RRC state to the second RRC state; and transmit paging information to the relay WTRU in response to the state change, wherein when the second RRC state is an RRC idle state or an RRC inactive state, the paging information includes discontinuous reception of DRX loop information by the WTRU.

Description

[0001] This application is a divisional application of Chinese invention patent application No. 202280031054.7, filed on March 29, 2022.

[0002] Cross-references to related applications

[0003] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 167,307, filed March 29, 2021; U.S. Provisional Patent Application No. 63 / 185,634, filed May 7, 2021; and U.S. Provisional Patent Application No. 63 / 249,832, filed September 29, 2021, the entire contents of which are incorporated herein by reference for all purposes. Background Technology

[0004] The first version of 3GPP Release 16 (Release 16) for New Radio (NR) sidelinks (SL) has been developed, and it focuses solely on supporting vehicle-to-everything (V2X) related road safety services. Release 16 is designed to support broadcast, multicast, and unicast communications in both out-of-coverage and in-network-coverage scenarios.

[0005] Regarding coverage extension for SL-based communications, the version 13 solution for UE-to-network (UE-to-network) relay is limited to Evolved Universal Terrestrial Radio Access (EUTRA) based technologies and therefore cannot be applied to NR-based systems, for both Next Generation Radio Access Network (NG-RAN) and NR-based sidelink communications. Regarding UE-to-UE coverage extension, current proximity accessibility is limited to single-hop sidelinks via EUTRA-based or NR-based sidelink technologies. However, given the limited coverage of single-hop sidelinks, this approach is insufficient without Uu reference point interface coverage. Accordingly, sidelink connectivity should be further extended within the NR framework to support enhanced QoS requirements. The disclosure herein addresses these and other issues. Summary of the Invention

[0006] In one representative aspect, a wireless transmit / receive unit (WTRU) is disclosed, the WTRU including a circuit system configured to: establish a connection with a relay WTRU; establish a connection with a network via the relay WTRU; receive an RRC indication of a state change from a first Radio Resource Control (RRC) state to a second RRC state of the WTRU, wherein the first RRC state is different from the second RRC state; change the state from the first RRC state to the second RRC state; and transmit paging information to the relay WTRU in response to the state change, wherein the paging information includes discontinuous reception of DRX loop information by the WTRU when the second RRC state is an RRC idle state or an RRC inactive state.

[0007] In another representative aspect, a method performed by a Wireless Transmit / Receive Unit (WTRU) is disclosed, the method comprising: establishing a connection with a relay WTRU; establishing a connection with a network via the relay WTRU; receiving an RRC indication of a state change from a first Radio Resource Control (RRC) state to a second RRC state from the WTRU, wherein the first RRC state is different from the second RRC state; changing the state from the first RRC state to the second RRC state; and transmitting paging information to the relay WTRU in response to the state change, wherein the paging information includes discontinuous reception of DRX loop information by the WTRU when the second RRC state is an RRC idle state or an RRC inactive state.

[0008] In another representative aspect, a relay wireless transmit / receive unit (WTRU) is disclosed, the relay WTRU including a circuit system configured to: establish a connection with a remote WTRU; establish a connection with a network to forward messages to the remote WTRU; receive an indication of a state change of the remote WTRU; receive paging information from the remote WTRU, wherein the paging information includes discontinuously received DRX loop information of the WTRU, wherein the content of the paging information depends on the state of the remote WTRU; and forward the paging information received from the network to the remote WTRU when the remote WTRU is in an RRC idle state or an RRC inactive state. Attached Figure Description

[0009] 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 exemplary. Therefore, the drawings (figures) and specific embodiments should not be considered limiting, and other equally valid examples are possible and contemplated. Additionally, similar reference numerals (“ref.”) in the figures indicate similar elements, and wherein:

[0010] Figure 1A This is a system diagram illustrating an exemplary communication system;

[0011] Figure 1B It shows that it can be used Figure 1A A system diagram of an exemplary wireless transmit / receive unit (WTRU) used within the communication system shown;

[0012] Figure 1C It shows that it can be used Figure 1A A system diagram of an exemplary radio access network (RAN) and an exemplary core network (CN) used within the communication system shown;

[0013] Figure 1D It shows that it can be used Figure 1A System diagram of another exemplary RAN and another exemplary CN used in the communication system shown;

[0014] Figure 2 A diagram depicts the user plane protocol stack used for UE-to-network relay;

[0015] Figure 3 A diagram depicts the control plane protocol stack used for UE-to-network relay;

[0016] Figure 4 An exemplary timing diagram depicting paging opportunities is provided;

[0017] Figure 5 An exemplary flowchart is depicted for calculating the permissible sidelink time slots for relay paging messages using a relay WTRU;

[0018] Figure 6 An exemplary flowchart is depicted showing which of the network configuration paging timings should be used for wake-up and monitoring in a specific DRX cycle for a relay WTRU;

[0019] Figure 7 An exemplary flowchart is depicted showing one or both of the system information changes and paging opportunities of a relay WTRU in handling remote WTRUs.

[0020] Figure 8 An exemplary flowchart is depicted showing how a relay WTRU transmits updated system information to a remote WTRU based on a state change of the remote WTRU.

[0021] Figure 9 An exemplary flowchart is depicted showing how a relay WTRU forwards updated system information based on the type of information received; and

[0022] Figure 10 An exemplary flowchart is depicted for a relay WTRU processing a paging short message containing a public warning system indication. Detailed Implementation

[0023] In the following detailed description, numerous 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 may be practiced without some or all of the specific details set forth herein. In other instances, well-known methods, processes, components, and circuits have not been described in detail so as not to obscure the following description. Furthermore, embodiments and examples not specifically described herein may be practiced in place of, or in combination with, the embodiments and other examples expressly, implicitly, and / or inherently described, disclosed, or otherwise provided (collectively, the “Provided”) herein. Although various embodiments are described and / or claimed herein, in which apparatuses, systems, devices, etc., and / or any elements thereof perform operations, processes, algorithms, functions, etc., and / or any part thereof, it should be understood that any embodiment described herein and / or protected by the claims presupposes that any apparatus, system, device, etc., and / or any element thereof is configured to perform any operation, process, algorithm, function, etc., and / or any part thereof.

[0024] Exemplary communication system

[0025] The methods, apparatus, and systems provided herein are well-suited for communications involving both wired and wireless networks. (Compared to...) Figures 1A to 1D An overview of various types of wireless devices and infrastructures is provided, wherein various elements of the network may utilize, perform, be arranged according to, and / or be adapted to and / or configured with respect to the methods, apparatuses and systems provided herein.

[0026] A detailed description of exemplary embodiments will now be described with reference to the accompanying drawings. While this specification provides detailed examples of possible specific implementations, it should be noted that the details are intended to be exemplary and in no way limit the scope of this application. In the following detailed description, numerous 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 may be practiced without some or all of the specific details set forth herein. In other instances, well-known methods, processes, components, and circuits have not been described in detail so as not to obscure the following description. Furthermore, embodiments and examples not specifically described herein may be practiced in place of, or in combination with, the embodiments and other examples expressly, implicitly, and / or inherently described, disclosed, or otherwise provided (collectively, “provided”) herein.

[0027] Figure 1AThis is a schematic diagram illustrating an exemplary communication system 100 that can be implemented in one or more of the disclosed embodiments. Communication system 100 can be a multiple access system providing content such as voice, data, video, messaging, and broadcasting to multiple wireless users. Communication system 100 enables multiple wireless users to access such content through the sharing of system resources (including wireless bandwidth). For example, communication system 100 may employ one or more channel access methods, such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal FDMA (OFDMA), Single Carrier FDMA (SC-FDMA), Zero-Tail Unique Word DFT Extended OFDM (ZT UW DTS-sOFDM), Unique Word OFDM (UW-OFDM), Resource Block Filtered OFDM, Filter Bank Multicarrier (FBMC), etc.

[0028] like Figure 1A As shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RAN 104 / 113, CN 106 / 115, Public Switched Telephone Network (PSTN) 108, Internet 110, and other networks 112. However, 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, and 102d may be any type of device configured to operate and / or communicate in a wireless environment. As examples, WTRUs 102a, 102b, 102c, and 102d (any of which may be referred to as a “station” and / or “STA”) may be configured to transmit and / or receive wireless signals and may include user equipment (UE), mobile stations, fixed or mobile user units, subscription-based units, pagers, cellular phones, personal digital assistants (PDAs), smartphones, laptops, netbooks, personal computers, wireless sensors, hotspots or Mi-Fi devices, Internet of Things (IoT) devices, watches or other wearable devices, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in industrial and / or automated processing chain environments), consumer electronics devices, devices operating on commercial and / or industrial wireless networks, etc. Any of WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0029] The communication system 100 may also include base station 114a and / or base station 114b. Each of base stations 114a and 114b may be any type of device configured to wirelessly interface with at least one of WTRUs 102a, 102b, 102c, and 102d to facilitate access to one or more communication networks, such as CN 106 / 115, Internet 110, and / or other networks 112. As an example, base stations 114a and 114b may be base transceiver stations (BTS), Node Bs, evolved Node Bs, home Node Bs, home evolved Node Bs, gNBs, NR Node Bs, site controllers, access points (APs), wireless routers, etc. Although base stations 114a and 114b are each depicted as a single element, it should be understood that base stations 114a and 114b may include any number of interconnected base stations and / or network elements.

[0030] 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 (BSCs), radio network controllers (RNCs), relay nodes, etc. Base station 114a and / or base station 114b may be configured to transmit and / or receive radio signals on one or more carrier frequencies (which may be referred to as cells (not shown)). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage of radio services to a specific geographic area, which may be relatively fixed or changeable over time. A cell may be further divided into cell sectors. For example, the cell associated with base station 114a may be divided into three sectors. 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 sector of the cell. For example, beamforming may be used to transmit and / or receive signals in desired spatial directions.

[0031] Base stations 114a and 114b can communicate with one or more of WTRUs 102a, 102b, 102c, and 102d via air interface 116, which can be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). Any suitable radio access technology (RAT) can be used to establish air interface 116.

[0032] 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, base stations 114a and WTRUs 102a, 102b, and 102c in RAN 104 / 113 may implement radio technologies such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may use Wideband CDMA (WCDMA) to establish air interfaces 115 / 116 / 117. WCDMA may include communication protocols such as High-Speed ​​Packet Access (HSPA) and / or evolved HSPA (HSPA+). HSPA may include High-Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High-Speed ​​UL Packet Access (HSUPA).

[0033] In the implementation scheme, base station 114a and WTRUs 102a, 102b, 102c can implement radio technologies such as evolved UMTS terrestrial radio access (E-UTRA), which can use Long Term Evolution (LTE) and / or Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-A Pro) to establish air interface 116.

[0034] In the implementation scheme, base station 114a and WTRUs 102a, 102b, 102c can enable radio technology such as NR radio access, which can use New Radio (NR) to establish air interface 116.

[0035] In the implementation scheme, base station 114a and WTRUs 102a, 102b, and 102c can implement multiple radio access technologies. For example, base station 114a and WTRUs 102a, 102b, and 102c can, for example, use a dual connectivity (DC) principle to implement both LTE and NR radio access together. Therefore, the air interface utilized by WTRUs 102a, 102b, and 102c can 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).

[0036] In other implementations, base station 114a and WTRUs 102a, 102b, and 102c can implement radio technologies such as IEEE 802.11 (i.e., WiFi), IEEE 802.16 (i.e., WiMAX), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Provisional Standard 2000 (IS-2000), Provisional Standard 95 (IS-95), Provisional Standard 856 (IS-856), Global System for Mobile Communications (GSM), GSM Enhanced Data Rate Evolution (EDGE), and GSM EDGE (GERAN).

[0037] Figure 1A Base station 114b can be, for example, a wireless router, a home node B, a home evolution node B, or an access point, and can utilize any suitable RAT to facilitate wireless connectivity in localized areas such as commercial locations, homes, vehicles, campuses, industrial facilities, air corridors (e.g., for use by drones), roads, etc. In one embodiment, base station 114b and WTRUs 102c, 102d can implement radio technologies such as IEEE 802.11 to establish a wireless local area network (WLAN). In another embodiment, base station 114b and WTRUs 102c, 102d can implement radio technologies such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, base station 114b and WTRUs 102c, 102d can utilize cellular-based RATs (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish picocells or femtocells. Figure 1A As shown, base station 114b may have a direct connection to Internet 110. Therefore, base station 114b may not need to access Internet 110 via CN 106 / 115.

[0038] RAN 104 / 113 can communicate with CN 106 / 115, which can be any type of network configured to provide voice, data, application, and / or Voice over Internet Protocol (VoIP) services to one or more of WTRU 102a, 102b, 102c, and 102d. Data can have different Quality of Service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. CN 106 / 115 can provide call control, billing services, location-based services, prepaid calling, internet connectivity, video distribution, etc., and / or perform advanced security functions such as user authentication. Although not explicitly stated... Figure 1AAs shown, but it should be understood that RAN 104 / 113 and / or CN 106 / 115 can communicate directly or indirectly with other RANs that use the same RAT as RAN 104 / 113 or a different RAT. For example, in addition to being connected to RAN 104 / 113 which can utilize NR radio technology, CN 106 / 115 can also communicate with another RAN (not shown) that uses GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0039] CN 106 / 115 may also act as a gateway for WTRU 102a, 102b, 102c, 102d to access PSTN 108, Internet 110, and / or other networks 112. PSTN 108 may include a circuit-switched telephone network providing Common Old-Style Telephone Service (POTS). Internet 110 may include a global system of interconnected computer networks and devices using common communication protocols such as Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and / or Internet Protocol (IP) from the TCP / IP Internet Protocol suite. Network 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. For example, network 112 may include another CN connected to one or more RANs, which may use the same RAT as RAN 104 / 113 or a different RAT.

[0040] Some or all of the WTRUs 102a, 102b, 102c, and 102d in the communication system 100 may include multi-mode capabilities (e.g., WTRUs 102a, 102b, 102c, and 102d may include multiple transceivers for communicating with different wireless networks via different wireless links). For example, Figure 1A The WTRU 102c shown can be configured to communicate with a base station 114a that can employ cellular-based radio technology and with a base station 114b that can employ IEEE 802 radio technology.

[0041] Figure 1B This is a system diagram illustrating an exemplary WTRU 102. (See diagram below.) Figure 1B As shown, WTRU 102 may include a processor 118, a transceiver 120, a transmitting / receiving element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power supply 134, a Global Positioning System (GPS) chipset 136, and / or other peripheral devices 138, etc. It should be understood that, while remaining consistent with the implementation, WTRU 102 may include any sub-combination of the foregoing elements.

[0042] Processor 118 can be a general-purpose processor, a special-purpose processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. Processor 118 can perform signal encoding, data processing, power control, input / output processing, and / or any other functions that enable WTRU 102 to operate in a wireless environment. Processor 118 can be coupled to transceiver 120, which can be coupled to transmitting / receiving element 122. Although Figure 1B The processor 118 and transceiver 120 are depicted as separate components, but it should be understood that the processor 118 and transceiver 120 may be integrated together in an electronic package or chip.

[0043] Transmitting / receiving element 122 may be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) via air interface 116. For example, in one embodiment, transmitting / receiving element 122 may be an antenna configured to transmit and / or receive RF signals. In another embodiment, transmitting / receiving element 122 may be a transmitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In yet another embodiment, transmitting / receiving element 122 may be configured to transmit and / or receive both RF and optical signals. It should be understood that transmitting / receiving element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0044] Although the transmitting / receiving element 122 is in Figure 1B While depicted as a single element, WTRU 102 may include any number of transmitting / receiving elements 122. More specifically, WTRU 102 may employ MIMO technology. Therefore, in one embodiment, WTRU 102 may include two or more transmitting / receiving elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals via air interface 116.

[0045] Transceiver 120 can be configured to modulate signals transmitted by transmitting / receiving element 122 and demodulate signals received by transmitting / receiving element 122. As noted above, WTRU 102 may have multi-mode capability. For example, transceiver 120 may therefore include multiple transceivers to enable WTRU 102 to communicate via various RATs (such as NR and IEEE 802.11).

[0046] The processor 118 of 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) 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, keypad 126, and / or display / touchpad 128. Furthermore, the processor 118 may access information from any type of suitable memory (such as non-removable memory 130 and / or removable memory 132) and store data in any type of suitable memory. Non-removable memory 130 may include random access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. Removable memory 132 may include a user identity module (SIM) card, memory stick, secure digital storage (SD) card, etc. In other embodiments, the processor 118 may access information from memory that is not physically located on WTRU 102 (such as on a server or home computer (not shown)) and store data in that memory.

[0047] The processor 118 may receive power from the power supply 134 and may be configured to distribute and / or control power to other components in the WTRU 102. The power supply 134 may be any suitable device for powering the WTRU 102. For example, the power supply 134 may include one or more dry cell battery packs (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0048] The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) about the current location of the WTRU 102. In addition to or instead of the information from the GPS chipset 136, the WTRU 102 may receive location information from base stations (e.g., base stations 114a, 114b) via air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It should be understood that, while remaining consistent with the implementation, the WTRU 102 may acquire location information using any suitable location determination method.

[0049] The processor 118 may also be coupled to other peripheral devices 138, which may include one or more software and / or hardware modules providing additional features, functions, and / or wired or wireless connectivity. For example, peripheral device 138 may include an accelerometer, electronic compass, satellite transceiver, digital camera (for photos and / or video), Universal Serial Bus (USB) port, vibration device, television transceiver, hands-free headset, etc. Modules, FM radio units, digital music players, media players, video game player modules, internet browsers, virtual reality and / or augmented reality (VR / AR) devices, activity trackers, etc. Peripheral devices 138 may include one or more sensors, which may be one or more of the following: gyroscopes, accelerometers, Hall effect sensors, magnetometers, orientation sensors, proximity sensors, temperature sensors, time sensors; geolocation sensors; altimeters, light sensors, touch sensors, magnetometers, barometers, gesture sensors, biometric sensors, and / or humidity sensors.

[0050] WTRU 102 may include a full-duplex radio for which the transmission and reception of some or all signals (e.g., associated with specific subframes for UL (e.g., for transmission) and downlink (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit 139 for reducing and / or substantially eliminating self-interference through signal processing via hardware (e.g., a choke) or via a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, WTRU 102 may include a half-duplex radio for which the 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.

[0051] Figure 1C This is a system diagram illustrating RAN 104 and CN 106 according to one implementation scheme. As noted above, RAN 104 can communicate with WTRUs 102a, 102b, and 102c via air interface 116 using E-UTRA radio technology. RAN 104 can also communicate with CN 106.

[0052] RAN 104 may include evolved Node Bs 160a, 160b, and 160c; however, it should be understood that RAN 104 may include any number of evolved Node Bs while remaining consistent with the implementation scheme. Each evolved Node B 160a, 160b, and 160c may include one or more transceivers for communicating with WTRUs 102a, 102b, and 102c via air interface 116. In the implementation scheme, evolved Node Bs 160a, 160b, and 160c may implement MIMO technology. Therefore, evolved Node B 160a may, for example, use multiple antennas to transmit radio signals to and / or receive radio signals from WTRU 102a.

[0053] Each of the evolved nodes B 160a, 160b, and 160c can be associated with a specific cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, and user scheduling in the UL and / or DL, etc. Figure 1C As shown, evolution nodes B 160a, 160b, and 160c can communicate with each other via the X2 interface.

[0054] Figure 1C The CN 106 shown may include a Mobility Management Entity (MME) 162, a Serving Gateway (SGW) 164, and a Packet Data Network (PDN) Gateway (or PGW) 166. While each of the foregoing elements is depicted as part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0055] The MME 162 can connect to each of the evolved nodes B 162a, 162b, and 162c in RAN 104 via the S1 interface and can be used as a control node. For example, the MME 162 can be responsible for authenticating users of WTRUs 102a, 102b, and 102c, bearer activation / deactivation, selecting a specific serving gateway during the initial attachment of WTRUs 102a, 102b, and 102c, etc. The MME 162 can provide control plane functions for handover between RAN 104 and other RANs (not shown) employing other radio technologies such as GSM and / or WCDMA.

[0056] The SGW 164 can connect to each of the evolved Nodes B 160a, 160b, and 160c in RAN 104 via the S1 interface. The SGW 164 typically routes and forwards user data packets to and from WTRUs 102a, 102b, and 102c. The SGW 164 can perform other functions such as anchoring the user plane during inter-evolved Node B handovers, triggering paging when DL data is available for WTRUs 102a, 102b, and 102c, and managing and storing the context of WTRUs 102a, 102b, and 102c.

[0057] SGW 164 can be connected to PGW 166, which provides WTRU 102a, 102b, 102c with access to packet-switched networks (such as Internet 110) to facilitate communication between WTRU 102a, 102b, 102c and IP-enabled devices.

[0058] CN 106 can facilitate communication with other networks. For example, CN 106 can provide WTRUs 102a, 102b, and 102c with access to a circuit-switched network (such as PSTN 108) to facilitate communication between WTRUs 102a, 102b, and 102c and conventional landline communication equipment. For example, CN 106 may include an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between CN 106 and PSTN 108, or be able to communicate with such an IP gateway. Furthermore, CN 106 can provide WTRUs 102a, 102b, and 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0059] Despite WTRU in Figures 1A to 1D While described as a wireless terminal, it is conceivable that in some representative implementations, such a terminal may (e.g., temporarily or permanently) use a wired communication interface with a communication network.

[0060] In a representative implementation, the other network 112 may be a WLAN.

[0061] A WLAN in Infrastructure Basic Services Set (BSS) mode may have an access point (AP) for the BSS and one or more sites (STAs) associated with the AP. The AP may have an access or interface to a distribution system (DS) or another type of wired / wireless network that carries traffic to and / or carries traffic out of the BSS. Traffic originating outside the BSS and destined for a STA can reach and be delivered to the STA via the AP. Traffic originating from a STA and destined for a destination outside the BSS can be sent to the AP for delivery to the appropriate destination. Traffic between STAs within the BSS can be sent via the AP, for example, where a source STA can send traffic to the AP, and the AP can deliver the traffic to the destination STA. Traffic between STAs within the BSS can be considered and / or referred to as point-to-point traffic. Point-to-point traffic can be sent between source and destination STAs (e.g., directly between them) using Direct Link Establishment (DLS). In some representative implementations, the DLS may use 802.11e DLS or 802.11z Tunneled DLS (TDLS). WLANs using the Standalone BSS (IBSS) mode may not have an access point (AP), and STAs within the IBSS or using the IBSS (e.g., all STAs) can communicate directly with each other. The IBSS communication mode may sometimes be referred to as the "ad-hoc" communication mode in this document.

[0062] When operating in 802.11ac infrastructure mode or a similar mode, the AP can transmit beacons on a fixed channel, such as the primary channel. The primary channel can be of fixed width (e.g., a 20 MHz wide bandwidth) or dynamically set via signaling. The primary channel can be the operating channel of the BSS and can be used by the STA to establish a connection with the AP. In some representative implementations, such as in an 802.11 system, Carrier Sense Multiple Access / Collision Avoidance (CSMA / CA) can be implemented. For CSMA / CA, each STA (including the AP) can listen to the primary channel. If the primary channel is listened to / detected and / or determined to be busy by a particular STA, that STA can back off. A single STA (e.g., only one station) can transmit at any given time within a given BSS.

[0063] High-throughput (HT) STAs can communicate using a 40MHz wide channel, for example, by combining a primary 20MHz channel with adjacent or non-adjacent 20MHz channels to form a 40MHz wide channel.

[0064] The Very High Throughput (VHT) STA supports channels with widths of 20MHz, 40MHz, 80MHz, and / or 160MHz. 40MHz and / or 80MHz channels can be formed by combining consecutive 20MHz channels. A 160MHz channel can be formed by combining eight consecutive 20MHz channels, or by combining two non-consecutive 80MHz channels (this can be referred to as an 80+80 configuration). For the 80+80 configuration, after channel coding, data can be processed by a segment parser that can split the data into two streams. Inverse Fast Fourier Transform (IFFT) processing and time-domain processing can be performed separately on each stream. These streams can be mapped to two 80MHz channels, and data can be transmitted via the transmitting STA. At the receiver of the receiving STA, the operations described above for the 80+80 configuration can be reversed, and the combined data can be sent to Media Access Control (MAC).

[0065] 802.11af and 802.11ah support operating modes below 1 GHz. Compared to those used in 802.11n and 802.11ac, 802.11af and 802.11ah reduce channel operating bandwidth and carrier. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in the TV white space (TVWS) spectrum, while 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to representative implementations, 802.11ah may support instrument-type control / machine-type communications, such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support (e.g., only support) certain bandwidths and / or limited bandwidths. MTC devices may include batteries with battery life above a threshold (e.g., to maintain a very long battery life).

[0066] WLAN systems supporting multiple channels, as well as channel bandwidths such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include channels that can be designated as primary channels. A primary channel can have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel can be set and / or limited by STAs operating in the BSS (each supporting a minimum bandwidth operating mode). In the 802.11ah example, for STAs supporting (e.g., only supporting) a 1MHz mode (e.g., MTC type devices), the primary channel can 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 Sense and / or Network Allocation Vector (NAV) settings can depend on the status of the primary channel. If the primary channel is busy, for example, because an STA (supporting only the 1MHz operating mode) is transmitting to the AP, the entire available band can be considered busy even if most of the band remains idle and potentially available.

[0067] 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 available bandwidth for 802.11ah is 6MHz to 26MHz, depending on the country code.

[0068] Figure 1D This is a system diagram illustrating RAN 113 and CN 115 according to one implementation scheme. As noted above, RAN 113 may employ NR radio technology to communicate with WTRUs 102a, 102b, and 102c via air interface 116. RAN 113 may also communicate with CN 115.

[0069] RAN 113 may include gNBs 180a, 180b, and 180c, but it should be understood that RAN 113 may include any number of gNBs while remaining consistent with the implementation. Each gNB 180a, 180b, and 180c may include one or more transceivers for communication with WTRUs 102a, 102b, and 102c via air interface 116. In the implementation, gNBs 180a, 180b, and 180c may implement MIMO technology. For example, gNBs 180a and 180b may utilize beamforming to transmit and / or receive signals from gNBs 180a, 180b, and 180c. Therefore, gNB 180a may, for example, use multiple antennas to transmit radio signals to and / or receive radio signals from WTRU 102a. In the implementation, gNBs 180a, 180b, and 180c may implement carrier aggregation technology. For example, gNB 180a can transmit multiple component carriers to WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum, while the remaining component carriers may be on licensed spectrum. In an implementation, gNBs 180a, 180b, and 180c may implement coordinated multipoint (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNBs 180a and 180b (and / or gNB 180c).

[0070] WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c using transmissions associated with scalable parameter sets. For example, OFDM symbol spacing and / or OFDM subcarrier spacing can vary depending on different transmissions, different cells, and / or different portions of the radio transmission spectrum. WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c using subframes or transmission time intervals (TTIs) of various or scalable lengths (e.g., containing different numbers of OFDM symbols and / or continuously varying absolute time lengths).

[0071] gNBs 180a, 180b, and 180c can be configured to communicate with WTRUs 102a, 102b, and 102c in standalone and / or non-standalone configurations. In standalone configuration, WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c without accessing other RANs (e.g., evolved Node Bs 160a, 160b, and 160c). In standalone configuration, WTRUs 102a, 102b, and 102c can use one or more of gNBs 180a, 180b, and 180c as mobility anchors. In standalone configuration, WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c using signals in unlicensed frequency bands. In a non-standalone configuration, WTRUs 102a, 102b, and 102c can communicate or connect to gNBs 180a, 180b, and 180c, and also communicate or connect to other RANs (such as evolved Node Bs 160a, 160b, and 160c). For example, WTRUs 102a, 102b, and 102c can implement DC principles to communicate substantially simultaneously with one or more gNBs 180a, 180b, and 180c and one or more evolved Node Bs 160a, 160b, and 160c. In a non-standalone configuration, evolved Node Bs 160a, 160b, and 160c can be used as mobility anchors for WTRUs 102a, 102b, and 102c, and gNBs 180a, 180b, and 180c can provide additional coverage and / or throughput for serving WTRUs 102a, 102b, and 102c.

[0072] Each of gNBs 180a, 180b, and 180c can be associated with a specific cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, user scheduling in UL and / or DL, network slicing support, dual connectivity, interoperability between NR and E-UTRA, routing of user plane data to User Plane Functions (UPF) 184a and 184b, routing of control plane information to Access and Mobility Management Functions (AMF) 182a and 182b, etc. Figure 1D As shown, gNB 180a, 180b, and 180c can communicate with each other via the Xn interface.

[0073] Figure 1DThe CN 115 shown may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. Although each of the foregoing elements is depicted as part of the CN 115, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0074] AMF 182a and 182b can connect to one or more of the gNBs 180a, 180b, and 180c in RAN 113 via the N2 interface and can be used as control nodes. For example, AMF 182a and 182b can be responsible for authenticating users of WTRU 102a, 102b, and 102c, supporting network slicing (e.g., handling different Protocol Data Unit (PDU) sessions with different requirements), selecting specific SMF 183a and 183b, managing registration areas, terminating (Non-Access Stratum) (NAS) signaling, mobility management, etc. AMF 182a and 182b can use network slicing to customize CN support for WTRU 102a, 102b, and 102c based on the type of service used by WTRU 102a, 102b, and 102c. For example, different network slices can be established for different use cases, such as services that rely on Ultra-Reliable Low Latency (URLLC) access, services that rely on Enhanced Mobile Broadband (eMBB) access, services for Machine Type Communication (MTC) access, etc. AMF 162 can provide control plane functions for switching between RAN 113 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies (such as WiFi)).

[0075] SMFs 183a and 183b can connect to AMFs 182a and 182b in CN 115 via the N11 interface. SMFs 183a and 183b can also connect to UPFs 184a and 184b in CN 115 via the N4 interface. SMFs 183a and 183b can select and control UPFs 184a and 184b, and configure traffic routing through UPFs 184a and 184b. SMFs 183a and 183b can perform other functions, such as managing and allocating WTRU / UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, and providing downlink data notifications. PDU session types can be IP-based, non-IP-based, Ethernet-based, etc.

[0076] UPF 184a and 184b can be connected via the N3 interface to one or more of the gNBs 180a, 180b, and 180c in RAN 113. These gNBs can provide WTRU 102a, 102b, and 102c with access to packet-switched networks (such as Internet 110) to facilitate communication between WTRU 102a, 102b, and 102c and IP-enabled devices. UPF 184 and 184b can perform other functions such as routing and forwarding packets, enforcing user plane policies, supporting multihomed PDU sessions, handling user plane QoS, buffering downlink packets, and providing mobility anchoring.

[0077] CN 115 can facilitate communication with other networks. For example, CN 115 may include an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between CN 115 and PSTN 108, or be able to communicate with such an IP gateway. Furthermore, CN 115 may provide WTRUs 102a, 102b, and 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 one embodiment, WTRUs 102a, 102b, and 102c may be connected to DN 185a and 185b via UPF 184a and 184b through their N3 interfaces and the N6 interface between UPF 184a and 184b and local data networks (DNs) 185a and 185b.

[0078] Given Figures 1A to 1D as well as Figures 1A to 1D The corresponding descriptions herein refer to one or more of the following functions, which may be performed by one or more emulation devices (not shown): WTRU 102a-d, base station 114a-b, evolved Node B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-ab, UPF 184a-b, SMF 183a-b, DN 185a-b, and / or any one or more other devices described herein. An emulation device may be one or more devices configured to mimic one or more of the functions described herein. For example, an emulation device may be used to test other devices and / or simulate network and / or WTRU functions.

[0079] Simulation devices can be designed to perform one or more tests on other devices in laboratory and / or carrier network environments. 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 to test other devices within the communication network. The one or more simulation devices may perform one or more or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. Simulation devices may be directly coupled to another device for testing purposes and / or may use over-the-air wireless communication to perform tests.

[0080] 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 devices may be used in test scenarios within a test laboratory and / or non-deployed (e.g., testing) wired and / or wireless communication networks to perform testing of one or more components. The one or more simulation devices may be test equipment. Direct RF coupling and / or wireless communication via an RF circuit system (e.g., which may include one or more antennas) may be used by the simulation devices to transmit and / or receive data.

[0081] The examples provided in this article do not limit the applicability of the subject matter to other wireless technologies, such as using the same or different principles that may apply.

[0082] As explained herein, a radio transmit / receive unit (WTRU) can be an example of a user equipment (UE). Therefore, the terms UE and WTRU are used interchangeably herein.

[0083] introduction

[0084] UE / WTRU to Network (NW) Relay in 3GPP Release 13

[0085] As described in 3GPP TS 36.300 - TSGRAN E-UTRA and E-UTRAN General Description Phase 2 (V15.4.0), 3GPP Release 13 introduced a relay from a near-field servicing (ProSe) UE to a network relay to extend network coverage to out-of-coverage UEs by using PC5 device-to-device (D2D) communication between the out-of-coverage UE and the network relay, as detailed in the relevant section below:

[0086] ProSe UE to Network Relay provides general L3 forwarding functionality, enabling the relaying of any type of IP traffic between a remote UE and the network. One-to-one and one-to-many sidelink communication is available between the remote UE and the ProSe UE to Network Relay. Only a single carrier (i.e., the public-safe ProSe carrier) is supported for both the remote UE and the relay UE (i.e., the Uu and PC5 link interfaces should use the same carrier for both the relay and remote UEs). The remote UE is authorized by the upper layer and can operate within or outside the coverage of the public-safe ProSe carrier, including public-safe ProSe carriers used for UE to Network Relay discovery, (re)selection, and communication. The ProSe UE to Network Relay is always within the coverage of the evolved UMTS RAN (E-UTRAN). ProSe UE to Network Relay and the remote UE perform sidelink communication and sidelink discovery as described in sections 23.10 and 23.11, respectively.

[0087] Relay selection from UE / WTRU to NW trunk

[0088] ProSe UE-to-NW relay selection / reselection is performed based on a combination of Access Layer (AS) quality measurements (such as Reference Signal Received Power (RSRP)) and upper-layer standards. This is described in 3GPP TS 36.300 - TSGRAN E-UTRA and E-UTRAN General Description Phase 2 (V15.4.0), which is further detailed in the Phase 2 specification, as follows:

[0089] The eNB controls whether the UE can act as a ProSe UE to network relay:

[0090] a. If the eNB broadcasts any information related to ProSe UE-to-network relay operation, then ProSe UE-to-network relay operation is supported in the cell;

[0091] b.eNB can provide:

[0092] i. Transmission resources for ProSe UE to network relay discovery using broadcast signaling in the RRC_IDLE state and dedicated signaling in the RRC_CONNECTED state of Radio Resource Control (RRC);

[0093] ii. Receive resources used for ProSe UE to discover network relays using broadcast signaling;

[0094] iii. Before initiating a UE-to-network relay discovery procedure, the eNB may broadcast the minimum and / or maximum Uu Link Quality (RSRP) thresholds that the UE must adhere to for ProSe UE-to-network relay. In RRC_IDLE, when the eNB broadcasts the transport resource pool, the UE uses the thresholds to proactively start or stop the UE-to-network relay discovery process. 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 begin ProSe UE-to-network relay discovery;

[0095] iv. If the eNB does not broadcast the transport resource pool for ProSe-UE to network relay discovery, the UE can initiate a request for ProSe-UE to network relay discovery resources by using dedicated signaling, taking into account these broadcast thresholds.

[0096] c. 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.

[0097] For a ProSe UE-to-Network Relay to perform sidelink (SL) communication for ProSe UE-to-Network Relay operations, it must be in the RRC_CONNECTED state. After receiving a Layer 2 link establishment request or Temporary Mobile Group Identity (TMGI) monitoring request (upper-layer message) 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 can provide resources for ProSe UE-to-Network Relay communication.

[0098] The remote UE can decide when to begin monitoring ProSe UE-to-Network Relay Discovery. Depending on the configuration of resources used for ProSe UE-to-Network Relay Discovery, the remote UE can transmit a ProSe UE-to-Network Relay Discovery Request message when it is in RRC_IDLE or RRC_CONNECTED state. The eNB can broadcast a threshold, which the remote UE uses to determine whether it can transmit a ProSe UE-to-Network Relay Discovery Request message to connect or communicate with a ProSe UE-to-Network Relay UE. In RRC_CONNECTED state, the remote UE uses the broadcast threshold to determine whether it can 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 can use broadcast or dedicated signaling to provide transmission resources and broadcast signaling to provide reception resources for ProSe UE-to-Network Relay operation. When RSRP exceeds the broadcast threshold, the remote UE stops using ProSe UE-to-Network Relay Discovery and communication resources.

[0099] Note: The exact timing of traffic switching from Uu to PC5 or from PC5 to Uu can be traced back to higher layers.

[0100] The remote UE performs radio measurements at the PC5 interface and uses them, along with higher-layer standards, 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 standards. The remote UE selects a ProSe UE-to-network relay that meets the higher-layer standards and has the best PC5 link quality among all suitable ProSe UE-to-network relays.

[0101] A remote UE triggers ProSe UE to reselect a network trunk under the following circumstances:

[0102] a. The current PC5 signal strength from the ProSe UE to the network relay is lower than the configured signal strength threshold;

[0103] b. Its link release message from ProSe UE to network relay receiver layer 2 (upper layer message).

[0104] UE / WTRU to Network Relay for Wearable Devices

[0105] In 3GPP Release 14, research was conducted on UE-to-NW relay in the RAN for commercial use cases tailored for wearable and IoT devices. While no specifications were produced from this research, technical reports (TRs) provided some preferred solutions for such relays. According to 3GPP TR 36.746 – Research on Further Enhancements to LTE D2D, UE-to-Network Relay for IoT and Wearable Devices (V15.1.1), in contrast to ProSe UE-to-NW relay using the L3 (IP layer) relay method, based on… Figure 2 and Figure 3 The protocol stack shown indicates that the UE to NW relay of the wearable device is expected to be an L2 relay.

[0106] Connection establishment for unicast links in NR V2X

[0107] Previous versions of the LTE specification used a relay solution based on a one-to-one communication link established at the upper layer (ProSe layer) between two UEs (remote UE and UE-to-NW relay). This connection was transparent to the Access Layer (AS) layer, and the connection management signaling and procedures performed at the upper layer were carried by the AS layer data channel. Therefore, the AS layer was unaware of this one-to-one connection.

[0108] In NR V2X (Release 16), the AS layer supports the concept of a unicast link between two UEs. Such unicast links are initiated by the upper layer (as in a ProSe one-to-one connection). However, the AS is informed of the existence of such unicast links and any data transmitted between peer UEs in a unicast manner. Using this knowledge, the AS layer can support hybrid Automatic Repeat Request (HARQ) feedback, Channel Quality Indicator (CQI) feedback, and unicast-specific power control schemes.

[0109] Unicast links at the AS layer are supported via PC5-Radio Resource Control (RRC) connections. In 3GPP TS38.300-NR and NG-Radio Access Network (RAN) General Description Phase 2 (V16.1.1), the PC5-RRC connection is defined in the relevant section as follows:

[0110] A PC5-RRC connection is a logical connection between a source layer 2ID and a destination layer 2ID pair in the AS. One PC5-RRC connection corresponds to one PC5 unicast link. PC5-RRC signaling, as specified in Sub-clause 5.X.9, can be initiated after the corresponding PC5 unicast link is established. When the PC5 unicast link is released as indicated by the upper layer, the PC5-RRC connection and its corresponding sidelink signaling radio bearer (SRB) and sidelink data radio bearer (DRB) are released.

[0111] For each unicast PC5-RRC connection, a sidelink SRB is used to transmit PC5-S (signaling) messages before PC5-S security is established. A sidelink SRB is used to transmit PC5-S messages to establish PC5-S security. A sidelink SRB is used to transmit PC5-S messages after PC5-S security has been established, and to protect those messages. A sidelink SRB is used to transmit PC5-RRC signaling, to protect that signaling, and to send it only after PC5-S security has been established.

[0112] PC5-RRC signaling includes sidelink configuration messages (RRCReconfigurationSidelink), in which a UE configures receive (RX) related parameters for each sidelink radio bearer (SLRB) in a peer UE. Such reconfiguration messages can configure parameters for each protocol in the L2 stack (Serving Data Adaptation Protocol (SDAP), Packet Data Convergence Protocol (PDCP), etc.). The receiving UE can acknowledge or reject such configuration, depending on whether it can support the configuration proposed by the peer UE.

[0113] Paging in NR

[0114] In NR Uu, the UE / WTRU can use discontinuous reception (DRX) in the RRC_IDLE and RRC_INACTIVE states to reduce power consumption. The UE monitors a paging opportunity (PO) in each DRX cycle. A PO is a set of Physical Downlink Control Channel (PDCCH) monitoring opportunities and may include multiple time slots (e.g., subframes or OFDM symbols) in which paging downlink control information (DCI) can be transmitted. According to 3GPP TS 38.300-NR and NG-RAN General Description Phase 2 (V16.1.1), a paging frame (PF) is a radio frame and may contain one or more POs or the start of a PO.

[0115] In multi-beam operation, the UE assumes that the same paging message and the same short message are repeated in all transmit beams, and therefore the beam selected for receiving the paging message and short message depends on the specific UE implementation. The paging message is identical for both RAN-initiated and CN-initiated paging and includes a set of paging records. The paging message may contain one or more paging records (i.e., one or more UE IDs) corresponding to a UE mapped to the same paging time and receiving paging from the network at that time. According to 3GPP TS 38.300-NR and NG-RAN General Description Phase 2 (V16.1.1), the UE ID in the paging record can be a 5G Serving Temporary Mobile Subscriber Identifier (5G-S-TMSI) (48 bits) when using CN paging, or an Inactive Radio Network Temporary Identifier (I-RNTI) (40 bits) when using RAN paging.

[0116] A UE in the IDLE / INACTIVE state determines its paging frame (PF) and paging timing (PO) based on either of the following:

[0117] a. Paging frame configuration in the System Information Block (SIB).

[0118] b. UE-specific or default DRX loop.

[0119] i. Specifically, a UE in RRC_IDLE determines its DRX cycle based on the minimum of the following:

[0120] 1) The default DRX loop broadcast in SIB, and

[0121] 2) UE-specific DRX loop provided in Dedicated Non-Access Stratum (NAS) signaling.

[0122] ii. A UE in RRC_INACTIVE determines its DRX cycle based on the minimum of the following:

[0123] 1) The default DRX loop broadcast in SIB.

[0124] 2) UE-specific DRX loops provided in Dedicated Non-Access Stratum (NAS) signaling, and

[0125] 3) UE-specific DRX provided in dedicated radio resource control (RRC) signaling

[0126] cycle.

[0127] c. UE ID (i.e., 5G-S-TMSI).

[0128] PF and PO are defined according to the following formulas in 3GPP TS 38.304-NR and NG-RAN IDLE mode specification (V16.3.0).

[0129] The single-frequency network (SFN) used for the power frequency (PF) is determined by the following:

[0130] (SFN+PF_offset)mod T=(T div N)*(UE_ID mod N)

[0131] The Index(i_s) indicating the index of the PO is determined by the following:

[0132] i_s = floor(UE_ID / N) mod Ns

[0133] The following parameters are used in the calculation of PF and i_s above:

[0134] T: The UE's DRX period (if configured by RRC and / or the upper layer, T is determined by the shortest DRX value among the UE-specific DRX values ​​and the default DRX value broadcast in the system information. In RRC_IDLE state, if the UE-specific DRX is not configured by the upper layer, the default value is applied).

[0135] N: Total number of paging frames in T.

[0136] Ns: Number of paging opportunities for PF.

[0137] PF_offset: The offset used to determine PF.

[0138] UE_ID:5G-S-TMSI mod 1024.

[0139] The timing of PDCCH monitoring for paging is determined according to the pagingSearchSpace as specified in 3GPP TS 38.213, and if configured as specified in 3GPP TS 38.331, according to firstPDCCH-MonitoringOccasionOfPO and nrofPDCCH-MonitoringOccasionPerSSB-InPO. When SearchSpaceId is configured to 0 for pagingSearchSpace, the timing of PDCCH monitoring for paging is the same as that for Residual Minimal System Information (RMSI) as defined in Clause 13 of 3GPP TS 38.213.

[0140] When SearchSpaceId is configured as 0 for pagingSearchSpace, Ns is either 1 or 2. For Ns=1, there is only one PO in the PF starting from the first PDCCH monitoring moment of paging. For Ns=2, the PO is located in either the first half-frame (i_s=0) or the second half-frame (i_s=1) of the PF.

[0141] When the SearchSpaceId configured for pagingSearchSpace is non-zero, the UE monitors the (i_s+1)th PO. A PO is a set of “S*X” consecutive PDCCH monitoring opportunities, where “S” is the number of actual transmitted synchronization signal blocks (SSBs) determined according to ssb-PositionsInBurst in SIB1, and X is nrofPDCCH-MonitoringOccasionPerSSB-InPO (if configured), otherwise equal to 1. The [x*S+K]th PDCCH monitoring opportunity in the PO for paging corresponds to the Kth transmitted SSB, where x = 0, 1, ..., X-1, K = 1, 2, ..., S. PDCCH monitoring opportunities for paging that do not overlap with the UL symbol (determined according to tdd-UL-DL-ConfigurationCommon) are sequentially numbered in the PF starting from zero, beginning with the first PDCCH monitoring opportunity for paging. When firstPDCCH-MonitoringOccasionOfPO exists, the starting PDCCH monitoring opportunity number for the (i_s+1)th PO is the (i_s+1)th value of the firstPDCCH-MonitoringOccasionOfPO parameter; otherwise, it is equal to i_s*S*X. If X>1, then when the UE detects a PDCCH transmission addressing a Paging Radio Network Temporary Identifier (P-RNTI) within its PO, the UE does not need to monitor subsequent PDCCH monitoring opportunities for that PO according to the 3GPP TS 38.304-NR and NG-RAN IDLE mode specification (V16.3.0).

[0142] The following parameters are used in the calculation of PF and i_s above:

[0143] T: The UE's DRX period (if configured by RRC and / or the upper layer, T is determined by the shortest DRX value among the UE-specific DRX values ​​and the default DRX value broadcast in the system information. In RRC_IDLE state, if the UE-specific DRX is not configured by the upper layer, the default value is applied).

[0144] N: Total number of paging frames in T.

[0145] Ns: Number of paging opportunities for PF.

[0146] PF_offset: The offset used to determine PF.

[0147] UE_ID:5G-S-TMSI mod 1024.

[0148] The parameters Ns, nAndPagingFrameOffset, nrofPDCCH-MonitoringOccasionPerSSB-InPO, and the length of the default DRX cycle are signaled in SIB1. The values ​​of N and PF_offset are derived from the parameter nAndPagingFrameOffset as defined in TS 38.331. The parameter first-PDCCH-MonitoringOccasionOfPO is signaled in SIB1 for paging in the initial DL BWP. For paging in DL BWPs other than the initial DL BWP, the parameter first-PDCCH-MonitoringOccasionOfPO is signaled in the corresponding BWP configuration in the 3GPP TS 38.304-NR and NG-RAN IDLE mode specification (V16.3.0).

[0149] Paging from UE / WTRU to NW trunk

[0150] In the System Information (SI) for LTE Wearable Devices, three options for paging reception for remote UEs are studied in accordance with 3GPP TR 36.746 - Study on further enhancements to LTE D2D, UE to network relay for IoT and wearable devices (V15.1.1).

[0151] a. Option 1 - Remote UE monitors its own PO for receiving NW paging.

[0152] b. Option 2 - The relay UE monitors the PO associated with each of its connected remote UEs and forwards paging messages (if received) to the remote UEs.

[0153] c. Option 3 - The relay UE receives any paging messages associated with the connected remote UE in the relay UE's PO.

[0154] Option 2 was recommended in the study. Option 2 is also assumed for NR UE to NW relay in version 17.

[0155] SI notification in paging messages

[0156] The UE may receive a notification of a modified SI and / or PWS indication (therefore referred to as an SI notification) during paging. This SI notification can be sent on the paging channel in a so-called Short Message Service (SMS). The SMS can individually indicate the presence of a PWS SIB being broadcast by the network (for emergency situations). Additionally, the SMS can individually indicate that one or more of the cell's SIBs have changed. A UE notified of a modified SI or PWS indication can follow the normal SI acquisition procedure to obtain the applicable SI.

[0157] Problem Statement

[0158] In a side-link (SL) UE / WTRU to NW relay for NR, it is assumed that the remote UE / WTRU uses Option 2, as defined in 3GPP TR36.746 – Study on Further Enhancements to LTE D2D, UE to Network Relay for IoT and Wearable Devices (V15.1.1), to receive paging from the NW. Specifically, the relay UE monitors the PO of the connected remote UE and relays any received paging messages to the remote UE. Essentially, this raises several issues as described below.

[0159] Power consumption at relay UE / WTRU

[0160] The remote UE PO is defined based on the UE's 5G-S-TMSI. Therefore, in addition to the relay UE's own PO for a remote UE with multiple PC5-RRC connections, the relay UE may need to monitor multiple different POs configured by the network. This is in... Figure 4 As shown, relay UE 401 needs to monitor its own paging timing (shown as 402). Relay UE 401 can also monitor the paging timings of its remote UEs 403 and 405, which happen to occur in different time slots, shown as 404 and 406 respectively. As the number of remote UEs increases, the power savings of relay UEs in IDLE DRX (i.e., in RRC_IDLE or RRC_INACTIVE) decrease. This reduction becomes more pronounced as the number of remote UEs served by the relay increases, and as we begin to consider more complex architectures such as multi-hop relays.

[0161] While other options would be to change the definition of the PO of the remote UE so that the remote UE under a single relay UE would have the same / similar PO, or simply to transmit the paging of the remote UE in the PO of the relay, this would eliminate the fundamental advantage of option 2, as the remote UE has the flexibility to receive paging messages via Uu or via the relay without notifying the network of the change.

[0162] Another aspect of the power consumption of a relay UE is related to the need to use multiple unicast transmissions per unicast link to forward a single paging message (which may contain multiple paging records, thus allowing the paging records to be associated with remote UEs connected to the same relay). This problem could become even more severe if we support multiple unicast links between a single remote UE and a relay UE for Uu relay connections.

[0163] Therefore, a question can be raised regarding the following: How can Option 2 be implemented at the relay UE / WTRU in a power-efficient manner (i.e., minimizing the additional power consumption at the relay UE / WTRU associated with the PO associated with all remote UE / WTRUs)?

[0164] Power consumption at remote UE / WTRU

[0165] UEs in RRC_IDLE / RRC_INACTIVE states served by Uu will be configured with DRX defined based on their paging DRX cycle and PO timing. This allows UEs to conserve power while in these states. If a UE in RRC_IDLE / RRC_INACTIVE receives paging via a relay UE, it needs to monitor the sidelink instead of Uu. To achieve similar power savings, a limited monitoring of the sidelink should be limited for remote UEs to receive relay paging. While this limited monitoring time should have some temporal relationship with the UE's Uu PO (assuming Option 2 is used), a precise one-to-one relationship cannot be derived due to uncertainties associated with relaying on the sidelink (aspects of sidelink characteristics, such as the need to perform resource selection using Mode 2 on a shared resource pool, and factors associated with the relay itself, such as relay delay and beam configuration).

[0166] Therefore, another question arises: how to avoid requiring remote UEs / WTRUs in RRC_IDLE / RRC_INACTIVE states to continuously monitor the sidelink to receive Uu paging when connected to the UE / WTRU to the NW trunk, and how to define a finite monitoring period that describes the uncertainty associated with Uu. Currently, there is no concept of paging timing on the sidelink.

[0167] Due to the security concerns surrounding the identity of remote UE / WTRUs, there is a lack of knowledge regarding the relationship between remote UE / WTRUs and paging records.

[0168] L2 relay inherently implements data transmission security within its protocol stack. Specifically, because the Packet Data Convergence Protocol (PDCP) is end-to-end, encrypted data transmissions made by the remote UE / NW cannot be decoded by the relay when transmitted to the NW / remote UE.

[0169] On the other hand, the paging timing of the remote UE is calculated using the 5G-S-TMSI of the remote UE. To prevent this information from being known to the relay UE (which may be an attacker), it is preferable that the relay UE only knows the paging timing itself and not the remote UE ID. However, since multiple UEs can be mapped to the same PO, the relay UE cannot know whether a particular paging message received at the PO is associated with a remote UE or with which remote UE. This can lead to inefficiencies associated with transmitting relayed paging messages at the relay UE, such as repeating paging messages multiple times or transmitting paging messages to unpaging remote UEs.

[0170] Therefore, since the UE / WTRU ID of the remote UE / WTRU is hidden from the relay UE / WTRU, another question arises: how to avoid redundant transmission of paging messages by the relay UE / WTRU.

[0171] A method for efficient paging of SL UE / WTRU to NW trunk.

[0172] Method for paging reception by relay UE / WTRU.

[0173] The relay UE / WTRU determines the remote UE / WTRU PO to be monitored based on the information in the active PO indication.

[0174] In one solution, a relay UE that may be in RRC_IDLE / RRC_INACTIVE state can receive an active PO indication from the network. This indication can notify a remote UE that one or more paging messages will be sent at one or more upcoming paging times associated with another UE, and can also indicate which PO, PO group, remote UE, remote UE group, paging frame, or paging frame group will be paged in the near future.

[0175] A relay UE can determine whether to monitor an upcoming paging time or a paging time in the future period based on information in such an indication, along with possible knowledge of whether one or more specific UEs associated with / referenced by the paging timing are currently connected to the relay UE. Specifically, the relay UE can receive an Activity PO indication from the network, which applies to a predefined, (pre)configured, or indicated future period. If the Activity PO indication indicates that a paging message will be sent for a specific UE / PO / PF / etc., and the relay UE is currently serving a specific UE associated with it (e.g., having a PC5-RRC unicast link with the UE), then the relay UE can monitor / wake up to monitor the paging channel at the time associated with the specific UE / PO / PF / etc. Otherwise, the relay UE may not need to wake up / monitor the paging channel at this time.

[0176] Timing of activity paging instructions

[0177] A relay UE can be configured to monitor the PDCCH at one or more defined / configured times when it is in RRC_IDLE / RRC_INACTIVE, where the relay UE can expect an active paging indication. In addition to the relay UE's paging-related PDCCH monitoring timings, the relay UE may also monitor the PDCCH at such times. The relay UE may receive an active paging indication at any of the following times or combinations:

[0178] a. During the IDLE / INACTIVE paging or paging monitoring period of the relay UE.

[0179] i. Specifically, a relay UE may receive an active paging indication at the same PDCCH monitoring time associated with its own paging time.

[0180] b. At a time related to the paging timing or paging monitoring timing of the relay UE.

[0181] i. For example, the UE may be configured with a time offset from the first / last monitoring time associated with its paging time in timeslots, symbols, radio frames, etc.

[0182] ii. For example, the UE can be configured to receive an active paging indication in a predefined time slot or set of time slots within its own paging frame.

[0183] iii. For example, the UE may be configured to receive an active paging indication at a predefined time slot or set of time slots within a frame that contains the first / last PDCCH monitoring time slot associated with the UE's paging time slot.

[0184] c. At another PO configured by the network and defined for receiving active paging indications.

[0185] i. For example, a UE can be configured to receive an active paging indication at another PO configured by the network using the current paging configuration. The UE can also be configured with specific rules regarding how to determine the PO associated with the reception of the active paging indication. Such rules can be defined with respect to the current PO of the relay UE or independently of the current PO of the relay UE. These rules may involve determining the PO used to receive the active paging indication, but using different parameters (e.g., UE ID, T, etc.) in the calculation of the PF / PO for the UE.

[0186] 1. For example, a UE can be configured to receive an active paging indication in a PO after / before its own PO.

[0187] 2. For example, the UE can be configured to receive an active paging indication in the PO calculated using a predefined or configured UE ID (instead of 5G-S-TMSI).

[0188] 3. For example, the UE may be configured to receive an active paging indication at a PO defined by using a value of T (i.e., DRX cycle), which is different from the UE’s defined DRX cycle (e.g., using the minimum defined DRX cycle in the specification).

[0189] d. At a predefined or configured frame / slot / symbol.

[0190] The timing of the expected PO can also depend on the DRX configuration itself. Specifically (and to handle large configured DRX cases), when the DRX cycle has a first set of values ​​or a range of values, the UE can be configured with a first expected time for receiving messages, and when the DRX cycle has a second set of values ​​or a range of values, the UE can be configured with a second / different expected time for receiving messages.

[0191] The relay UE may determine the frequency (how often) or density of Uu resources / timing for receiving messages based on any one or a combination of the following:

[0192] a. DRX loop of relay UE.

[0193] i. For example, with longer DRX cycles, messages can be received / expected more frequently.

[0194] ii. Depending on whether the relay UE is configured with a minimum DRX cycle, messages can be expected on different resource sets.

[0195] b. Number of connected UEs.

[0196] i. For example, for a relay UE with a large number of connected remote UEs, messages can be received / expected more frequently.

[0197] c. The UE ID and / or mode / timing of the PO associated with the connected remote UE.

[0198] i. For example, the frequency or timing associated with message reception may depend on the number / pattern of paging events associated with the connected remote UE. For example, a relay UE may receive messages more frequently in time slots that are (temporally) closer to the paging event location of the connected remote UE. For example, a relay UE may receive a message once for every N paging events associated with the connected remote UE. For example, a message may be located in at most / at least a number of time slots before / after any PO of the connected remote UE.

[0199] d. QoS / bearer / service established at the remote UE.

[0200] i. For example, a relay UE may receive / expect messages more frequently from one or more remote UEs that have a bearer / QoS flow / priority associated with a higher QoS transition.

[0201] e. RRC status associated with one or more remote UEs.

[0202] i. For example, if at least one of the remote UEs is in the RRC_INACTIVE state, the relay UE can receive / expect messages more frequently.

[0203] Time validity of activity paging instructions

[0204] Active paging indications can be associated with time validity. Specifically, a relay UE can determine the valid time period for information in an active paging indication, which may be based on the number of frames and / or time slots and / or symbols, or on the PO configured in the NW, or on the PF / PO configured in the NW, or defined / indicated in the active paging indication message itself. Specifically, a relay UE can determine whether to target the paging monitoring PDCCH at a specific time based on the information in the received active paging indication message, provided that the specific time in question falls within the time validity period of the active paging indication. The UE can use any of the following or a combination to determine the time validity of the active paging indication message:

[0205] a. Based on the information in the message itself.

[0206] i. For example, an active paging indication message can indicate the number of frames, subframes, DRX cycles, POs, etc., that it is indicating active paging.

[0207] b. Use predefined cycles.

[0208] i. For example, an active paging indication may always provide information for a fixed set of DRX cycles, POs, etc., after the time the active paging indication is received, or for a defined time period starting from a defined moment after the active paging indication is received.

[0209] ii. For example, an activity paging indication may provide activity (whether paging is provided or not) for a set of POs configured by the network in a DRX cycle after the indication is received, wherein the DRX cycle may be a specific DRX cycle (e.g., minimum / maximum configurable DRX cycle, default DRX cycle) or a DRX cycle indicated in the message itself.

[0210] c. Until the next received paging instruction message.

[0211] i. For example, the UE may determine its paging reception activity for each PO after receiving a paging indication message, and maintain the determined activity until another paging indication message is received.

[0212] Specific to time validity, in one exemplary solution, the UE can anticipate an activity paging indication for each DRX cycle. In one exemplary implementation, the UE can use information in the activity paging indication message to derive monitoring behavior for the POs configured by the NW in the DRX cycle following the receipt of the activity paging indication. In such implementations, when the UE does not receive an activity paging indication within the expected time associated with the DRX cycle, the UE can be configured with default behavior that will be applied in the DRX cycle. For example, a relay UE can assume that all POs in the DRX cycle following a missed or unreceived activity paging indication message are considered active. For example, a relay UE can consider every other PO / no PO in the DRX cycle following a missed or unreceived activity paging indication message to be active. For example, a relay UE can consider an active PO in the DRX cycle to be the same as an active PO in a previous DRX cycle.

[0213] In another exemplary implementation, the UE may expect / receive an activity paging indication message only if one or more of the upcoming POs are indicated as active. In such an implementation, the UE may assume that the next indicated PO is active only. Alternatively, the UE may assume that the next N instances of the indicated PO are active, where N may be predefined or further configured by the network.

[0214] In each of the above embodiments, the UE may also determine whether to monitor the PO based on the activity identified as part of the activity paging indication message and whether the PO associated with it is currently connected to a relay UE, as defined herein. Specifically, the UE monitors the PO only when the message indicates activity in the PO, and the UE has a PC5-RRC connection to the relay UE associated with the PO.

[0215] The content of the active paging instruction and its association with the remote UE / WTRU.

[0216] The relay UE may receive any of the following information in the active paging indication message:

[0217] a. The validity period of the message, as described in this article.

[0218] b. Connection mode gap mode, as further described herein, if the relay UE is in

[0219] RRC_CONNECTED.

[0220] c. Message format.

[0221] i. For example, if the message contains a bitmap, the message may also define the granularity of the bitmap (e.g., whether each bit is associated with a single PO or a group of POs, and the information required for the relay UE to determine the packet and / or mapping to each group).

[0222] ii. For example, if the message contains a bitmap, the message may also define the grouping of UEIDs associated with each bit (e.g., the number of UEs in each group associated with each bit).

[0223] d. One or more UE IDs, which may be 5G-S-TMSI, I-RNTI, L2 source and / or destination IDs. Such IDs may be associated with a UE that will receive a pager in the PO below or in a future PO.

[0224] i. For example, a relay UE can receive the UE ID of a connected remote UE, which the NW expects to page in the next DRX cycle after (by the network) transmitting an Active Paging Indication message. Specifically, if the UE ID is included in the message, the relay UE can determine that a particular remote UE (with the UE ID provided in the message) will be paged within a predefined / configured time period.

[0225] ii. Such IDs can also be truncated versions of any of the IDs mentioned above. Specifically, if a relay UE receives a message with a specific truncated ID, the relay UE can determine one or more remote UEs whose subset of the network can page its full UE ID matches the received truncated UE ID.

[0226] e. Identify the index of the remote UE.

[0227] i. For example, the message may contain an index that identifies a remote UE in a list of UEs. Such a list of UEs could be a list of remote UEs currently in service by a relay UE at the current time or at a previous time. This list of UEs can be derived from a list of remote UEs provided and / or updated by the relay UE to the network, as further described herein. Specifically, if the message contains an index of a particular remote UE, the relay UE can determine that the indexed UE may be paged by the network at some future time period.

[0228] f. Identify the index of one or more NW configuration paging timings or paging frames or groups thereof.

[0229] i. For example, it may contain an index of a specific PO in a set of POs that reference the NW configuration based on a predefined or configured number.

[0230] ii. For example, it may contain an index of a group of POs in a collection that references the POs configured in the NW, where the grouping and indexing of the groups may be further predefined or configured.

[0231] iii. Specifically, the relay UE may maintain the association between the UE (e.g., one of its remote UEs) and the Uu PO configured for that UE. When a message contains an index of the PO or group of POs to which one of the remote UEs of the relay UE is associated based on the association described above, the relay UE may determine that it should monitor the PO (i.e., the remote UE may be paged at an upcoming paging time).

[0232] g. A bitmap, wherein each bit in the bitmap is associated with a remote UE, a remote UE group, a PO or PF, or a PO or PF group, etc.

[0233] i. For example, the message may contain a bitmap, where each bit in the bitmap is associated with a UE, a UE group, a PO, or a PO group. Specifically, if the corresponding bit in the bitmap is set, the relay UE can determine that the network can page one or more remote UEs in a connected remote UE group.

[0234] ii. For example, each bit in the bitmap can be associated with each possible value (mod N) of the remote UE ID. If a bit is set, the relay UE can assume that at least one remote UE whose PO is mapped to any PO defined by that value (mod N) of the UE ID can be paged.

[0235] Mechanism for receiving activity paging indication messages

[0236] A relay UE can use any of the following to receive an active paging indication message:

[0237] a. Dedicated DCI on PDCCH.

[0238] i. For example, DCI can be used to encode information associated with an active paging indication message on the PDCCH. Specifically, a relay UE can receive information from an active paging indication message encoded as part of the DCI.

[0239] b. Use MAC control elements (MAC CE).

[0240] i. For example, a relay UE can identify a paging indication message based on a logical channel (LCH) ID or MAC header information, which may indicate a MAC CE, and the information may be embedded in the content of the MAC CE.

[0241] c. Use paging messages.

[0242] i. For example, a relay UE may receive an active paging indication message within a paging message. Specifically, the relay UE may receive the active paging indication message within an RRC message sent to the relay UE on the paging channel (PCH) (i.e., after the UE decodes the PDCCH using P-RNTI). The relay UE may also receive the message within a separate RRC message received on the PCH. In this case, the message may contain an identifier indicating that the RRC message contains an active paging indication message. Alternatively, the message (or information associated with the message) may be included within a normal paging message containing other records. In this case, the message may be included at the beginning / end of the paging message, or it may be included as a string (instead of NAS information) associated with a specific UE ID IE (e.g., all zeros or a UE ID of varying length).

[0243] d. In paging messages indicated by short paging DCI.

[0244] i. For example, a relay UE may receive an indication in a short paging DCI, wherein such an indication may indicate to the relay UE that the associated paging message has been replaced or contains an active paging indication message.

[0245] e. Use a dedicated (special) RNTI—for example, a relay (R)-RNTI.

[0246] i. The relay UE can be configured with a new RNTI (e.g., R-RNTI). The relay UE can receive active paging indication messages in the DCI or MAC CE obtained by decoding the PDCCH with the R-RNTI.

[0247] Relay UE / WTRU receives individual active paging indication messages based on its RRC status.

[0248] In one solution, a relay UE may receive individual activity paging indication messages depending on its RRC state. Specifically, a relay UE may receive a first message when it is in RRC_IDLE, and / or a second message when it is in RRC_INACTIVE, and / or a third message when it is in RRC_CONNECTED. The content / format of these messages may differ. For example, a relay UE in RRC_IDLE may receive an activity indication for any PO configured by the network. On the other hand, a relay UE in RRC_CONNECTED may receive an activity indication associated only with a subset of POs. Such a subset may be indicated as part of a message. Such a subset may be derived / based on information provided by the relay UE, as described herein, to further reduce the number of POs or UEs the network needs to report in the activity paging indication message.

[0249] Mechanism for determining / receiving UE / WTRU-PO association

[0250] Whether a relay UE monitors a PO associated with another UE (e.g., a remote UE) depends on whether the UE in question is connected to or served by the relay UE. For example, when a remote UE and a relay UE have a PC5-RRC connection, the relay UE can serve the remote UE. For example, when a remote UE has instructed it to request paging forwarding from a relay UE to which the remote UE is connected via PC5-RRC, the relay UE can serve the remote UE.

[0251] A relay UE can maintain associations between one or more PFs, POs, etc., and remote UEs, potentially for all served remote UEs. For example, a relay UE can maintain a PO associated with each of the remote UEs it serves. For example, a relay UE can maintain a table / list of all attached / served remote UEs and their corresponding POs and / or DRX cycles. The relay UE can determine the association between remote UEs and POs based on information obtained through any of the following:

[0252] a. Received directly from the remote UE itself.

[0253] i. For example, a relay UE may receive a PO from a remote UE in PC5-RRC signaling (e.g., in the form of an index to a table or an indirect mapping of the PO). For example, when a remote UE establishes a PC5-RRC connection with a relay UE, the remote UE may send a PO to the relay UE. For example, when the PO changes (e.g., due to RRC reconfiguration), the remote UE may send a PO to the relay UE.

[0254] ii. For example, a relay UE may receive information from a remote UE in PC5-RRC signaling that allows it to calculate the PO. Such information may be, for example, the UE / WTRU ID, the value of UE mod K (e.g., UE mod 1024), or a subset of the bits of the remote UE's UE ID.

[0255] b. Receive directly from the network.

[0256] i. For example, a relay UE may receive a PO from the network for a remote UE, for example, in an RRCReconfiguration message. For example, a relay UE may receive a PO indicating a new / released PC5-RRC connection after transmitting a SidelinkUEInformation to the network.

[0257] c. Calculated by the relay UE.

[0258] i. For example, a relay UE can receive the UE ID of a remote UE (from a remote UE or NW) and can use the UE ID of the remote UE to calculate the PO based on the paging configuration.

[0259] In each of the above mechanisms (received from the network or from a remote UE), the relay UE may also receive:

[0260] a. Information about which specific POs it should / should not monitor.

[0261] b. Information regarding whether monitoring of the PO for a specific remote UE is necessary.

[0262] i. The relay UE can indirectly derive this information from the PC5-RRC link monitoring status. Specifically, the relay UE can receive an indication (from the network, a remote UE, or from an upper layer) that the PC5-RRC link has been released. The relay UE can then stop monitoring all POs associated with the remote UE.

[0263] When referenced herein, the PO associated with a remote UE may include any of the associations described above. Similar to the above, a relay UE may also receive the remote UE's DRX cycle from the remote UE itself or from the network, as well as possible other DRX parameters that allow the relay UE to calculate the associated PO of the remote UE.

[0264] The remote UE / WTRU determines which DRX loop / message to send to the relay UE / WTRU.

[0265] In one solution, a remote UE may send one or more DRX cycles to a relay UE. In one example, the remote UE may send both its NAS-layer configured DRX cycle and its RRC-layer configured DRX cycle to the relay UE. If neither is configured, the UE may send only the other. If neither is configured, the remote UE may indicate this (by sending an empty field / message or by explicitly indicating it). Alternatively, if neither is configured, the remote UE may send a default DRX cycle. In another example, the remote UE may send the minimum of the DRX cycles to the relay UE. Specifically, the relay UE may send only the minimum of the NAS-layer configured DRX cycle and the RRC-layer configured DRX cycle. In this case, the relay UE may determine the remote UE's DRX cycle as the minimum of the DRX cycle received from the remote UE and the default DRX cycle. If no DRX cycle is received from the remote UE, the relay UE may use the default DRX cycle. In another solution, the relay UE can send the minimum of the DRX cycle configured at the NAS layer, the DRX cycle configured at the RRC layer, and the default DRX cycle. The relay UE can use the DRX cycle received from the remote UE to determine the DRX cycle to be used to determine the paging timing for the remote UE.

[0266] The remote UE can also determine which DRX cycle information to send to the relay UE based on its RRC state. For example, if the remote UE is in RRC_IDLE, it can send the DRX cycle configured by NAS (if one is configured), or the minimum value between the NAS value and the default value. If the remote UE is in RRC_INACTIVE, it can send the DRX cycle configured by NAS (if configured) and the DRX cycle configured by RRC (if configured), or the minimum value of the DRX cycles configured by NAS and RRC, or the minimum value of the DRX cycles configured by NAS and RRC, plus the default value.

[0267] The remote UE may send the DRX cycle when the connection is established, when the relay UE requests a change in the DRX cycle (e.g., the calculated minimum value), or when the remote UE's RRC state changes.

[0268] The remote UE / WTRU can determine whether to send the complete or partial UE / WTRU ID.

[0269] A remote UE may send the complete UE ID (I-RNTI and / or 5G-S-TMSI) or a partial UE ID (I-RNTI and / or 5G-S-TMSI-mod N). A remote UE may send only one of these to a given relay. The remote UE may determine whether to send the complete ID or a partial ID based on any of the following:

[0270] a. Network configuration:

[0271] i. For example, a remote UE may be (pre-)configured with a list of “trusted” trunk IDs (e.g., L2 IDs) in SIB or dedicated signaling. If the remote UE connects to a trunk from the “trusted” list, the remote UE may send its full UE ID.

[0272] ii. For example, if the remote UE is not configured with a list of trusted UEs, the remote UE may send a partial ID. After the connection with the relay is established, the remote UE may determine that the relay UE is a trusted relay (using other methods described herein), after which the remote UE may send the complete UE (either immediately upon a change in the UE ID or upon a relay request).

[0273] b. From a higher layer (e.g., after network access / authentication or remote or relay)

[0274] i. For example, a trusted UE ID can be notified to a remote UE from an upper layer (e.g., the NAS layer). This can occur after initial access to the relay UE or authentication of the core network. Similar to other implementations, the remote UE can initially send a partial ID and then send the full ID once the relay has been determined to be trusted.

[0275] c. Based on the previous connection with the relay UE

[0276] i. For example, a remote UE can maintain a list of trusted L2 IDs (after connection and authentication). If a remote UE initiates a connection to the same L2 ID as in the past, the remote UE can assume a trusted relay UE.

[0277] A trunk UE can connect to a remote UE that has provided a full UE ID and / or a remote UE that has provided a partial UE ID. The trunk UE may read and forward paging differently depending on the specific situation / UE (whether it has a full or partial ID).

[0278] For remote UEs that provide partial IDs, the relay UE may forward any messages received in the PO associated with the remote UE to the remote UE, regardless of their content. The relay UE may also include a list of UE IDs included in the paging message along with the forwarded paging message from the network.

[0279] For a remote UE that provides a complete UE ID, the relay UE can decode the paging message and send a PC5-RRC paging message with the content described herein (i.e., possibly without a UE ID). Furthermore, in this case, the relay UE can determine other fields that will be included in the paging message (e.g., paging type) (but not in other cases).

[0280] Relay UE / WTRU sends updated link information to NW

[0281] In a solution that can be used in conjunction with previous solutions, the relay UE can send remote UE link information to the network. For example, this information can be used to reduce / optimize the size of active paging indication messages. Specifically, the relay UE can send a list of connected remote UEs to the network. For example, the relay UE can send an indication that one or more UEs are connected / disconnected from the relay UE (from the perspective of PC5-RRC messages).

[0282] Rules for sending messages

[0283] A relay UE may send updated link information based on one or more of the following rules, or a combination of these rules:

[0284] a. periodically.

[0285] i. For example, a relay UE can be configured to periodically report link information.

[0286] ii. For example, the periodicity of reporting may also depend on:

[0287] 1. Number of connected remote UEs.

[0288] 2. RRC status of relay UE.

[0289] 3. The RRC status of one or more remote UEs.

[0290] 4. QoS / service is relayed (e.g., a radio bearer established at either the remote UE and / or the relay UE).

[0291] b. When connecting a new remote UE.

[0292] c. When disconnecting (releasing) one or a configured number of PC5-RRC connections with a remote UE.

[0293] d. Depends on the size of the active paging indication message (e.g., the number of bits in the bitmap) and / or whether joining / leaving a remote UE causes a specific change in the size of such a message.

[0294] e. Depends on the power preference / capacity at the remote UE.

[0295] Message content

[0296] The relay UE may include any of the following in the updated link message:

[0297] a. A list of UE IDs associated with the connected remote UE (where this can be L2 source / destination ID, I-RNTI, 5G-S-TMSI, etc.).

[0298] b. The UEID of the most recently joined / left relay UE (e.g., since the last message transmission), along with an indication of joining or leaving for each UE.

[0299] c. A list of all POs associated with each of the linked remote UEs.

[0300] d. POs of UEs that have recently (e.g., since the last message transmission) joined / left the relay UE, along with the joining / leaving indication for the specific PO.

[0301] How to send a message

[0302] A relay UE can use any of the following to send messages:

[0303] a. UL RRC message transmission (e.g., when the relay UE is in RRC_CONNECTED).

[0304] i. For example, a relay UE can send a SidelinkUEInformation message.

[0305] b. Recovery procedure or similar RAN-based Notification Area Update (RNAU) procedure.

[0306] i. For example, a relay UE in RRC_INACTIVE state can trigger a recovery procedure and include the information in an RRC recovery request message or in another message transmitted along with the recovery request message.

[0307] Data transfer in c.INACTIVE.

[0308] For example, a relay UE (e.g., in RRC_INACTIVE) may transmit small data containing an RRC message.

[0309] d. Procedures similar to SI requests.

[0310] i. For example, a relay UE (e.g., in RRC_IDLE / RRC_INACTIVE) may send a procedure similar to an SI request, in which the requested system information (SI) is replaced by link information.

[0311] Relay / Remote UE / WTRU sends paging change request

[0312] In one solution, a relay UE may receive a paging change request from a remote UE. Upon receiving such a request, the relay UE may change from one paging reception method / option to another for a specific remote UE. Specifically, the relay UE may change from expecting to page the remote UE from its own PO to expecting to page the remote UE from its own PO (or vice versa). For example, the relay UE may start / stop monitoring for paging opportunities associated with the remote UE in question upon receiving such a paging change request. The relay UE may notify the network upon receiving the expected paging change from the remote UE. For example, the relay UE may transmit an RRC message to the NW upon receiving the paging change request from the remote UE. For example, the relay UE may initiate / restore an RRC connection upon receiving the paging change request from the remote UE. For example, the relay UE may initiate a procedure similar to an SI request or data transmission in an INACTIVE procedure upon receiving the paging change request message. The relay UE may include the UE ID (e.g., L2 source / destination ID) of the requesting remote UE in the message.

[0313] Upon receiving a message and / or notifying the network, the relay UE may change its paging monitoring behavior. The relay UE may perform any of the following:

[0314] a. It may be possible to start / stop monitoring of the PO associated with the remote UE that requested the change, even if there are no other remote UEs associated with the PO or if there are no previous remote UEs associated with the PO.

[0315] b. Decode active paging indication messages from the network in different ways, such as:

[0316] i. Change the expected location of the expected paging instruction message.

[0317] ii. Change the message encoding (e.g., number of bits, size, etc.).

[0318] iii. Change the mapping / interpretation of the encoding for each remote UE.

[0319] A remote UE may send a paging change request when it needs to receive paging from a relay UE (or no longer needs to receive paging). Such a request may be triggered because the remote UE no longer needs to receive paging. Such a request may be triggered because the remote UE directly starts / stops paging reception from the Uu while still connected via a relay, in which case reception via the relay is not required. Such a request may be triggered by conditions requiring redundancy in paging reception (directly via the Uu and via the relay). The remote UE may determine whether to receive paging directly via the Uu and / or via the relay and / or whether to send a paging change request based on one or more of the following conditions or a combination of these conditions or a change in these conditions:

[0320] a. Conditions for Uu links.

[0321] i. For example, Uu RSRP is higher / lower than a threshold. For example, a remote UE can monitor paging on Uu when Uu RSRP is higher than the threshold and can monitor paging from the relay when Uu RSRP is lower than the threshold. When a remote UE monitors a paging change on the link opposite to Uu, it can notify the relay UE by sending a paging change request.

[0322] ii. For example, the UE triggers a Radio Link Failure (RLF) or an SL-RLF. For example, when an SL RLF is triggered at a remote UE, the remote UE may move from paging on the monitoring SL to paging on the monitoring Uu. The remote UE may also indicate these to the relay UE.

[0323] b. Conditions at the UE related to power consumption or temperature.

[0324] i. For example, the UE indicates overheating.

[0325] ii. For example, a change in UE power consumption preferences. For example, a remote UE may move to the paging on the monitoring SL and notify the relay when it receives such an indication.

[0326] c. Conditions regarding Uu between relays and networks.

[0327] i. Such conditions / measurements can be provided by the relay UE to the remote UE for further decision-making regarding which link to monitor for paging.

[0328] d. Conditions associated with the RRC status of the remote UE.

[0329] i. For example, a remote UE may send an indication when it moves from RRC_CONNECTED to RRC_IDLE / RRC_INACTIVE, or vice versa. This indication may be a message / signaling from the remote UE to the relay UE as an indication of a change in the remote UE's operational state. Exemplary indications of a state change may be PC5-RRC messages / signaling with direct or implicit state indication information. For example, when an indication notifies the relay UE that the remote UE is in RRC_IDLE / RRC_INACTIVE, the relay UE may monitor the remote UE's PO. When the remote UE is in RRC_CONNECTED, the relay UE may not monitor the remote UE's PO. e. Conditions on the sidelink.

[0330] i. For example, the measured Channel Busy Rate (CBR) moves above / below a threshold.

[0331] ii. For example, SL RSRP is higher / lower than a threshold. For example, when CBR exceeds the threshold, a remote UE may move to paging on the monitoring Uu. For example, a remote UE may move to paging on the monitoring Uu when SL RSRP is lower than the threshold and may monitor paging from a relay when SL RSRP is higher than the threshold.

[0332] f. Conditions related to the activity's carrying capacity.

[0333] i. For example, a remote UE is configured to request / prioritize bearers for paging reception on Uu and / or on sidelinks.

[0334] ii. If such a bearer is established / released / activated / deactivated, the remote UE may send an indication to the relay UE.

[0335] g. Conditions related to remote / relay UE mobility / coverage.

[0336] i. For example, a remote UE moves from the coverage area of ​​the same / different gNB to the coverage area of ​​a different / same gNB, RAN area, or tracking area, relative to a relay UE connected to / within its coverage area of ​​a gNB.

[0337] ii. For example, notify the remote UE of changes in the coverage / connectivity of the relay UE (e.g., via the receipt of system information) so that the relay / remote UE is within the coverage of the same / different gNB, RAN area, or tracking area.

[0338] h. Conditions associated with the tracking area / RAN notification area (TA / RNA) of a remote UE.

[0339] i. For example, if the cell on the direct interface is in the UE's configured TA / RNA, the remote UE can monitor paging directly on the Uu or on both the Uu and the trunk. Otherwise, the remote UE can monitor paging only from the trunk.

[0340] ii. A remote UE may send an indication to a relay UE while in motion, wherein the remote UE moves in / out of its TA / RNA relative to a direct link.

[0341] The above conditions, or combinations thereof, can also be used to determine situations where a remote UE can simultaneously monitor paging from both Uu and relays. For example, if the SL RSRP is below a threshold and / or the Uu RSRP is below a threshold, the remote UE can monitor paging from both Uu and SL. This can be incentivized to extend coverage for receiving paging messages.

[0342] In combination with other solutions, a remote UE can send a paging change request to the NW via Uu, or to the trunk channel via a trunk. The remote UE can receive / expect paging via Uu and / or the trunk based on either of the above conditions. For example, if the Uu RSRP is below a first threshold and above a second threshold, while the SL RSRP is above another threshold, the remote UE can receive paging via Uu and the trunk. The remote UE can send a paging change request before the expected change of paging source.

[0343] The remote UE / WTRU can indicate a subset of the PO (or beam) in the paging change request.

[0344] In one solution, a remote UE can indicate a subset of Points of Interest (POs) that it wants the relay UE to monitor on its behalf. This subset of POs can be associated with a finite time period (e.g., the next x DRX cycles). This subset of POs can also be a subset of POs where the relay UE should / should not monitor the remote UE according to rules. The remote UE can also indicate a subset of beams or time slots within the POs for the relay UE to monitor on its behalf.

[0345] The remote UE can determine, based on the conditions given above, a subset of POs, time slots, or beams that the relay UE should monitor based on a percentage of such opportunities. Specifically, for a given condition (e.g., a measurement of RSRP), the remote UE can be configured with a percentage of POs to monitor and can provide the POs and / or percentages to the relay UE. The relay UE can then monitor the desired POs or use the obtained percentages to derive the POs of the remote UE to be monitored.

[0346] In another solution, the remote UE can determine that it will be unable to monitor its PO for a certain period of time or time slot sequence in Uu or SL. The remote UE can indicate such a period of time or time slot sequence to the relay UE. For example, such unavailability may be caused by the following:

[0347] a. The remote UE determines the conflict between the SL transmit / receive and the remote UE's PO.

[0348] i. For example, a remote UE may need to receive SL during one or more POs (e.g., for another unicast link associated with the SL service) and may not be able to receive paging on the Uu in those POs.

[0349] ii. For example, a remote UE may perform / schedule transmission on the SL time slot associated with the paging reception and may receive paging for the PO directly from the Uu.

[0350] b. The remote UE needs to prioritize SL over Uu for a certain period of time (which may be related to a conflict between SL and Uu).

[0351] c. Remote UEs need to disable Uu monitoring for a certain period of time (e.g., due to power saving preferences, indications within the UE, etc.).

[0352] In another solution, the remote UE can indicate to the relay UE whether it can directly monitor paging on the Uu. This determination can be based on the conditions described above. In such solutions, whether the remote UE performs paging monitoring directly on the Uu may depend on subsequent indications / commands from the relay UE and / or the network. Alternatively, when the remote UE can directly monitor paging on the Uu, the remote UE can be configured with default behavior (always / never monitor paging on the Uu, or determine using the rules described herein).

[0353] The relay UE / WTRU indicates whether it can / cannot monitor paging on behalf of a remote UE / WTRU.

[0354] In a similar solution, the relay UE may notify the remote UE that the relay UE cannot monitor paging (potentially for a subset of POs / time slots). The relay UE may provide such an indication only if the remote UE indicates that it can monitor paging directly on the Uu. Specifically, such an indication to the remote UE may cause the remote UE to monitor paging directly via the Uu (potentially on a subset of time slots). Conditions similar to those described for paging change requests or indication of time slot subsets may be used by the relay UE to indicate to the remote UE that the relay UE cannot monitor paging to the remote UE. For example, the relay UE may prioritize SL transmission / reception over Uu for a period of time during which the remote UE's paging may be missed. The relay UE may then send such an indication to the remote UE, potentially indicating the missed POs.

[0355] When such an instruction is received, the remote UE may perform any of the following:

[0356] a. If a remote UE can receive its paging via Uu, the remote UE can directly monitor the paging on Uu, possibly only for POs sent by the relay UE in the indication.

[0357] b. If the remote UE cannot receive its paging via Uu, the remote UE may perform any one or a combination of the following:

[0358] i. Establish / restore RRC connections via relays (especially to avoid potentially missed paging messages sent by the network).

[0359] ii. Triggering trunk reselection (specifically to find an alternative trunk that can monitor paging for a remote UE). For example, a remote UE may trigger trunk and / or cell reselection. If a remote UE cannot find a suitable trunk, it may initiate RRC connection establishment / recovery to the currently connected trunk.

[0360] When a relay UE / WTRU receives a paging request, it initiates a connection / recovery procedure.

[0361] In one solution, a relay UE in RRC_IDLE / RRC_CONNECTED state can initiate a connection / recovery procedure upon receiving a paging message for a remote UE or in a PO associated with a connected remote UE.

[0362] The relay UE may also decide whether to perform such connection establishment based on one or more of the following conditions or a combination thereof:

[0363] a. Instructions in a paging message.

[0364] i. For example, a relay UE may receive an indication in a paging message that indicates whether the relay UE should initiate a connection / restore.

[0365] b. RRC status of the relay UE.

[0366] i. For example, a relay UE may initiate a connection establishment if it is in RRC_IDLE, but will not initiate such a connection if it is in RRC_INACTIVE.

[0367] c. The UE ID associated with the received paging message.

[0368] i. For example, if a relay UE receives a UEID associated with one of its associated remote UEs (e.g., L2 source / destination ID, 5G-S-TMSI, I-RNTI), the relay UE can initiate a connection establishment.

[0369] d. Establish or map the bearer / LCH on the Uu LCH at the remote UE.

[0370] i. For example, a relay UE may initiate connection establishment for a connected remote UE (possibly identified in a paging message) that has an LCH mapped to a Uu LCH and is configured (or requires) the relay UE to perform connection establishment / restore upon paging.

[0371] ii. For example, if a remote UE has at least one configured LCH (e.g., PC5 LCH) with a priority higher than a threshold or configured with attributes that require connection establishment / recovery by the relay, the relay UE may initiate connection establishment / recovery.

[0372] e. UE ID type in paging messages.

[0373] i. For example, if at least one of the UE IDs in the paging message or the associated UE ID is associated with the I-RNTI, the relay UE can initiate an RRC connection / recovery.

[0374] Relay UE / WTRU monitors paging associated with remote UE / WTRU within a limited time period.

[0375] In one solution, a relay UE can monitor paging associated with a remote UE for a limited time period since the last occurrence of a specific event. Such behavior can be further limited to a subset of scenarios such as:

[0376] a. The relay UE is configured to determine whether to perform finite-time monitoring based on the NW configuration.

[0377] b. The relay UE is configured to perform finite-time monitoring depending on the RRC status of the relay UE and / or the remote UE.

[0378] i. For example, when a remote UE and / or a relay UE is in RRC_IDLE, the relay UE performs finite-time monitoring of paging to the remote UE; otherwise, it performs paging monitoring to the remote UE without relying on such events / timers.

[0379] ii. For example, a relay UE may be configured with a timer for monitoring paging by remote UEs. As long as the timer is running, the relay UE can monitor paging associated with the remote UE. The relay UE can reset the timer upon the occurrence of one or more events. Such events may consist of any of the following: receiving transmissions, data, control, HARQ feedback, Channel State Information (CSI) requests / reports, SCI, etc., from the remote UE. These may be associated only with specific types of transmissions. For example, the timer may be reset upon receiving only a HARQ ACK, or a HARQ ACK or HARQ NACK.

[0380] c. Receive paging messages from the network, which may be associated with a remote UE or a PO of a remote UE.

[0381] d. Receive instructions or messages from the network, which may be associated with a remote UE.

[0382] e. Receive SL WUS (wake-up signal) for SL DRX control purposes or receive acknowledgments of such SL WUS.

[0383] f. Receive MAC CE (such as SL DRX command MAC CE).

[0384] Relay UE / WTRU monitoring for paging and / or system information (SI) modification may depend on the relay / remote UE / WTRU RRC status and / or paging change request.

[0385] The relay UE / WTRU determines the RRC status of the remote UE / WTRU.

[0386] The relay UE can be notified of the status of the remote UE:

[0387] a. From the network (e.g., via dedicated RRC signaling)

[0388] b. From a remote UE (e.g., via PC5-RRC signaling)

[0389] c. The RRC status of the remote UE is implicitly determined based on the following:

[0390] i. State transition signaling relayed by the relay UE. For example, as a result of receiving the signal, the relay UE can determine that the remote UE has moved from RRC_IDLE / RRC_INACTIVE.

[0391] ii. An adaptation layer and / or relay configuration for the remote UE exists at the relay UE. For example, the relay UE can determine whether the remote UE is in RRC_CONNECTED based on whether the remote UE has been configured with relay configuration (such as adaptation layer configuration, mapping in the ingress-egress LCH, etc.) (by the network).

[0392] iii. PC5 signaling or transmission / behavior performed by a remote UE associated with RRC_CONNECTED.

[0393] 1. For example, a relay UE can determine the Uu RRC state of a remote UE based on its SL DRX configuration with the remote UE. Specifically, if the remote UE requests / configures SL DRX on a unicast link with the relay UE, the relay UE can assume that the remote UE is in RRC_CONNECTED.

[0394] 2. For example, a relay UE may determine that a remote UE is in RRC_CONNECTED based on the presence and / or configuration of regular SL transmissions (e.g., configuration of SL RSRP reports, regular presence of SL CSI requests / reports, timers associated with SL data transmissions between the remote UE and the relay UE).

[0395] The relay UE / WTRU determines which paging opportunities to monitor.

[0396] The paging monitoring and / or SI monitoring behavior of a relay UE may depend on the RRC status of the relay and / or remote UEs. A relay UE may monitor paging timing or a subset of paging timing for all remote UEs known to be in RRC_IDLE / RRC_INACTIVE, in accordance with the methods described herein (indicated by the network in the active paging indication or by the remote UE in the paging change request).

[0397] Alternatively, a relay UE may monitor paging timings or subsets of paging timings for all PC5-RRC-connected remote UEs that are requested to monitor their paging timings based on the receipt of indications and / or paging change indication messages from the network.

[0398] When the relay UE itself is in RRC_CONNECTED state, the relay UE can stop monitoring paging opportunities for all PC5-RRC connected remote UEs. Specifically, in this case, the relay UE can rely on dedicated RRC signaling to receive paging messages from remote UEs. The relay UE can receive paging messages addressed to remote UEs within dedicated RRC messages. Upon receiving such paging messages, the relay UE can forward the paging message to the addressed remote UE within PC5-RRC signaling. For example, the dedicated RRC message containing the paging message may include the UE ID of the remote UE to which the paging message is intended.

[0399] The relay UE / WTRU determines how to handle SI modification indications in paging.

[0400] In one solution, the management / processing of a relay UE's reception of paging and / or SI modification indications from the network may depend on the RRC state of the relay / remote UE. As expressed above, when a remote UE changes state, it can send an indication via message transmission / signaling. An example could be a state change indication message / signaling that occurs when a remote UE moves from the RRC_CONNECTED state to the RRC_IDLE / RRC_INACTIVE state (or vice versa). Specifically:

[0401] a. If the relay UE is in RRC_CONNECTED state, then the relay UE may depend on the remote

[0402] The UE's RRC status is used to forward SI indications and / or information regarding the changed SI and / or actual SI. SI indication information indicates the availability of changed (updated) SI information (i.e., the actual, new SI information) from the network. Specifically:

[0403] i. If the remote UE is in RRC_CONNECTED state, the relay UE can forward the SI indication to the RRC_CONNECTED remote UE. The relay UE can send the indication immediately or when the relay UE obtains the updated SI. Furthermore, the relay UE can send a list of modified SIs to the remote UE based on the value labels in SIB1. Specifically, the relay UE can determine the SIs whose value labels have changed and send the changed SIs (or a subset, e.g., based on those of interest to the remote UE) to the remote UE.

[0404] And / or the SI value label has been changed.

[0405] ii. If the remote UE is in RRC_IDLE / RRC_INACTIVE, the relay UE may not forward the SI indication to the remote UE. Instead, the relay UE may send the modified SI itself (based on the changed value label) to the remote UE. Therefore, the RRC idle or RRC inactive state change indication (from RRC connected to RRC idle or inactive)

[0406] This can be associated with the relay UE sending changed (updated, actual) SI information to the remote UE. Alternatively, if the relay UE is in RRC_CONNECTED, the relay UE may first receive / determine the changed actual SI after receiving the SI indication.

[0407] Specifically, the relay UE can determine the changed SI based on the value tag received in SIB1. Based on the changed SI, the relay UE can transmit the changed SI (or a subset thereof, for example, based on those that the remote UE is interested in).

[0408] b. If the relay UE is in RRC_IDLE / RRC_INACTIVE, the relay UE can forward the modified SIs to all remote UEs, regardless of their RRC status. Specifically, the relay UE can determine the list of modified SIs (based on the value labels in SIB1 and / or the SIs of interest at the remote UEs) and can forward all (interested) SIs to each remote UE connected to the PC5-RRC.

[0409] In another solution, the management / processing of a relay UE's reception of paging and / or SI modification indications from the network may depend on whether the modified SI is of interest to the relay UE or needs to be received by the relay UE. Specifically:

[0410] a. If the relay UE receives an SI change indication and determines that (potentially all) of the changed SIs are of interest to the relay UE, the relay UE may forward the changed SIs to the remote UE without forwarding the SI change indication. On the other hand, if the relay UE determines that the modified SIs are not of interest to the relay UE (and may be of interest to the remote UE, and the remote UE may be in RRC_CONNECTED), the remote UE may only forward the SI change indication. Possibly, if the relay UE determines that the SI change indication is not of interest to the relay UE, and the remote UEs (or at least one remote UE, or at least N remote UEs) are in RRC_IDLE / RRC_INACTIVE, the relay may acquire and forward the changed SIs.

[0411] In another solution, the management / processing of the relay UE's reception of SI modification indications from the network may depend on whether the remote UE is interested in the changed SI. Specifically:

[0412] a. The relay UE may maintain a list of SIs of interest for each remote UE and may only forward the modified SI and / or SI change indication if the modified SI is of interest to the remote UE (possibly at least one of them). Otherwise, the relay UE may choose not to forward the SI indication and / or the modified SI.

[0413] In another solution, the management / processing of the relay UE's reception of SI modification indications from the network may depend on the number or type of SIBs / SIs that have been changed and / or are SIs / SIs of interest from remote UEs. For example, if the number of changed SIBs / SIs of interest is below a configured threshold, the relay may forward the changed SIs. Otherwise, the relay UE may only forward SI modification notifications. For example, the relay UE may receive and forward changed SIBs for certain specific SIBs or SIB types, while forwarding SIB modification indications for specific SIBs or SIB types. For example, the relay UE may always forward Public Warning System (PWS) SIBs or Location SIBs, but may only forward SI modification indications (instead of SIBs) for certain SIBs.

[0414] Combinations of the above solutions are also possible in terms of conditions for forwarding SIB or paging messages.

[0415] In another solution, the management / processing of paging and / or modified SI by the relay UE may depend on whether the relay UE is configured with a common search space in the current DL bandwidth portion. This solution may be specific to relay UEs in RRC_CONNECTED. Specifically:

[0416] a. If the relay UE is configured with a common search space in the current DL bandwidth portion, then the relay

[0417] UE can use one of the solutions defined above.

[0418] b. If the relay UE is not configured with a common search space in the current DL bandwidth portion.

[0419] i. Relay UEs can use dedicated RRC signaling to receive any modified SI directly from the network.

[0420] In this scenario, the timing of the relay UE monitoring the paging of the remote UE is not expected (for paging reception). Upon receiving a modified SI, if the modified SI is also deemed of interest to the remote UE, the relay UE may send the modified SI to the remote UE via PC5-RRC signaling.

[0421] ii. Alternatively, the relay UE may use dedicated RRC signaling to directly receive any modified SI from the network, and upon receiving a modified SI, may send the SI to the remote UE depending on the RRC status of the remote UE. Specifically:

[0422] 1. If the remote UE is in RRC_IDLE / RRC_INACTIVE, the relay UE can send the modified SI to the remote UE in PC5-RRC signaling.

[0423] 2. If the remote UE is in RRC_CONNECTED, the relay UE can send an indication of the modified SI and / or a list of modified SIs to the remote UE in PC5-RRC signaling.

[0424] In both success and error scenarios, the relay UE / WTRU receiving the paging message in dedicated signaling can respond to the network.

[0425] The network can use dedicated RRC signaling to send paging messages to a relay UE that is in RRC_CONNECTED state, but a remote UE may no longer be in RRC_CONNECTED state to a given relay UE. In this case, the network should be able to recognize the situation.

[0426] In one solution, the relay UE can send an acknowledgment message (if it has successfully reached / was able to successfully reach the remote UE) or a failure message (otherwise). The relay UE can send acknowledgment / failure messages:

[0427] a. When a dedicated paging message is received from a relay UE

[0428] i. For example, if a remote UE paged by the network in a dedicated paging message received by the relay UE does not have a PC5-RRC connection to the relay UE, the remote UE may send a failure message to the network. If the remote UE is connected, the relay UE may send an acknowledgment message to the network.

[0429] b. When attempting to forward paging messages via PC5-RRC.

[0430] i. For example, when forwarding a paging message to a remote UE, the remote UE can expect an acknowledgment (e.g., in RLC or PC5-RRC). If no acknowledgment is received, the relay UE can send a failure message to the network. Otherwise, if an acknowledgment is received from the remote UE, the relay UE can send an acknowledgment message.

[0431] Dedicated RRC messages and responses from a relay UE may take the form of request / response RRC signaling (e.g., RRCReconfiguration and acknowledgment / failure messages, or a new combination of RRC messages for delivering paging and corresponding responses). Alternatively, a remote UE may send a UL RRC message (e.g., ULInformationTransfer or similar message) if paging to a remote UE fails, and send no message if paging is successful.

[0432] Contents of the dedicated Uu RRC message sent from the network to the relay UE / WTRU

[0433] A dedicated RRC message may contain any of the following information:

[0434] a. The UE ID of the remote UE being paged on the network

[0435] i. The UE ID can be the I-RNTI of a remote UE, the 5G-S-TMSI, or the local UE ID.

[0436] ii. A relay UE may send a unicast PC5-RRC message to a remote UE whose UE ID is included in the paging message.

[0437] iii. The relay UE can determine the paging type to be included in the forwarded paging message based on whether the received ID for that UE is I-RNTI or 5G-S-TMSI (as described herein). This behavior can be the same for cases where the relay UE receives a paging message while monitoring the PO of a remote UE (i.e., not in dedicated signaling). Alternatively, the dedicated Uu RRC message can include the remote UE ID (which may be the local ID rather than the paging ID) and the paging type (RAN paging or CN paging), and the relay can reflect this paging type in the forwarded paging message.

[0438] b. The remote UE should initiate a connection establishment link / path on it (e.g., directly, via relay, etc.).

[0439] i. A relay UE can forward links / paths to a remote UE.

[0440] ii. Upon receiving the indicated link / path from the relay, the remote UE can initiate connection establishment / restore via that link.

[0441] c. Relay UE ID: The remote UE should initiate connection establishment via this relay UE ID in response to paging reception.

[0442] i. A relay UE can forward its relay UE ID to a remote UE. This relay UE ID may differ from its own ID (i.e., the network selects a different relay). Furthermore, if a different relay is selected, the relay UE can release the PC5-RRC connection after forwarding the paging to the remote UE.

[0443] ii. If the indicated relay UE ID does not match its current relay, the remote UE may release the PC5-RRC connection. The remote UE may then initiate connection establishment via the connected relay or the indicated relay, based on whether the UE ID / which UE ID is indicated in the paging message forwarded on the PC5-RRC.

[0444] d. CBR threshold used to determine which path / link to select

[0445] i. Relay UEs can forward such thresholds to remote UEs.

[0446] ii. The remote UE can determine whether to initiate connection establishment via direct or indirect means based on a comparison of the measured CBR with a threshold (e.g., if CBR > threshold, then via direct path).

[0447] The relay UE / WTRU determines the content of the PC5-RRC message containing the forwarded paging message.

[0448] The PC5-RRC message indicating paging to the remote UE (sent by the relay UE) may contain any information received by the relay UE and forwarded to the remote UE. Additionally, the relay UE may include the following information in the PC5-RRC message:

[0449] a. Paging type (e.g., CN paging, RAN paging). This type of field can be sent as an enumeration type.

[0450] i. For example, a relay UE can determine whether a paging is a CN paging or a RAN paging based on the following and indicate this to a remote UE:

[0451] 1. The type of ID received from the network in the dedicated Uu RRC message. For example, a relay UE can determine the paging type based on whether it receives an I-RNTI or a 5G-S-TMSI.

[0452] 2. Explicit / implicit indications in dedicated Uu RRC messages. For example, a relay UE may receive its local UE ID along with an indication in a dedicated Uu RRC message indicating whether it should send a CN paging or a RAN paging. The relay can then forward such indications.

[0453] ii. For example, upon receiving a paging message with a paging type of CN paging or RAN paging, a remote UE may treat it as if it were receiving a CN paging or a RAN paging respectively. A remote UE in RRC_IDLE receiving a RAN paging may ignore the message. Alternatively, it may send a PC5-RRC message indicating an error condition to a relay UE. Alternatively, it may initiate a connection establishment procedure to the network, possibly indicating an error condition to the network (in a cause value or in an RRC message / field).

[0454] iii. For example, a remote UE in RRC_INACTIVE that receives a paging message of type RAN paging can initiate a recovery procedure. A remote UE in RRC_INACTIVE that receives a paging message of type CN paging can transition to RRC_IDLE, release its context, and initiate a connection establishment procedure.

[0455] b.SI change / PWS notification indication.

[0456] i. For example, a relay UE may receive an SI change indication along with a paging message (or at a similar time). If the relay UE receives two separate paging messages within a configured time window (e.g., a paging message for a remote UE and an SI modification message), the relay UE may combine these two indications into a single PC5-RRC message. For example, if the relay UE receives a second message (PWS notification) after receiving the first message (e.g., a paging message for a remote UE) but before generating a PC5-RRC message, the relay UE may send both in a single PC5-RRC message.

[0457] c. SI or part of SI may be associated with an SI that has been modified by the network and for which SI modification has been sent, or may be associated with an SI that is of interest to a particular remote UE.

[0458] i. For example, a relay UE may indicate in a paging forwarding message that the included SI corresponds to a modified SI.

[0459] ii. For example, when a paging message containing an SI is received (e.g., a PC5-RRC message forwarded specifically for paging), the remote UE will assume that the SI corresponds to a changed SI and will update its own SI based on the content of the paging message.

[0460] d. The specific SIB or SI that was modified

[0461] i. For example, when a paging message indicating SI modification is received, the relay UE can read SIB1 to determine that SI / SIB has been modified, and can then indicate the modified SIB / SI to the remote UE in a PC5-RRC message.

[0462] e.SIB1 or a portion of SIB1 (e.g., validity label, region ID, etc.).

[0463] i. For example, whenever an SI modification is received, the relay UE may always forward the complete SIB1, or it may forward only the part of SIB1 associated with the modified SIB (such as the validity label) or all SIBs.

[0464] f. The UE ID of the remote UE being paged. For example, a relay UE may include only the UE ID of the remote UE being paged in a PC5-RRC message destined for that relay UE, without including other UE IDs in the paging record. The relay UE may repeatedly transmit PC5-RRC messages to each remote UE included in the paging message, and include only the remote UE ID corresponding to that remote UE in the corresponding message.

[0465] The timing of the transmission of the forwarded paging message may depend on its content.

[0466] In Mode 2, a relay UE transmitting a paging message can be configured with a time window for forwarding the paging message on the PC5 RRC. This time window can also depend on whether the paging message is carrying a UE paging, SI change indication, or PWS notification. Such a paging message can determine the minimum / maximum amount of time the UE has before generating a PC5-RRC message to forward the paging message and / or the resource selection window for transmitting the paging message. As described herein, if a paging message (e.g., including a paging message with an SI change indication or PWS notification) is received within an overlapping window, the relay UE can combine the messages.

[0467] In one example, a relay can forward certain paging messages immediately and other paging messages after a predefined or configured time period. For instance, a paging message containing a PWS notification and / or a UE paging can be forwarded immediately, while a paging message containing an SI modification can be forwarded only before / after the next modification period (or at a preconfigured time).

[0468] The timing of the transmission of the forwarded paging message may depend on the SL DRX activity time of the remote UE / WTRU.

[0469] In another example, the relay UE may forward the paging message only during the active time (e.g., as defined by the SL DRX) of the corresponding remote UE to which the paging message is being forwarded. Specifically, if the relay UE receives a paging message to be forwarded to the remote UE during the remote UE's inactive time, or if the remaining time in the remote UE's active time is less than a configured / predefined threshold, the relay UE may delay the transmission of the paging message until the subsequent active time of the remote UE.

[0470] In another example, a relay UE can forward SI modifications to all remote UEs in a multicast (e.g., using a multicast L2 ID). The relay UE can wait for a specific multicast activity time, or a time when all remote UEs are active, in order to forward the SI modifications.

[0471] When inactive, the relay UE / WTRU receiving a paging message can send an indication to the remote UE / WTRU.

[0472] In one solution, a relay UE can send an indication to one or more remote UEs when it receives a paging message for itself. This indication can be in the form of a PC5-RRC message, such as a release message or an SL reconfiguration message. Such messages can be in the form of an SL MAC CE or an SCI transmission dedicated to this purpose.

[0473] In some cases, a relay UE may send such messages on a sidelink, depending on either the RRC status of the relay UE and / or the remote UE, or information received by the remote UE in a paging message. For example:

[0474] a. (Transition to IDLE due to CN paging) When a relay UE in RRC_INACTIVE receives a core network paging message, the relay UE may send an indication to a remote UE. The relay UE may also send this message only to remote UEs in RRC_INACTIVE.

[0475] b. (Receipt of SI Notification) When the relay UE receives an SI change notification in a paging message, the relay UE may send an indication to the remote UE. The relay UE may also include the modified SI (or a subset thereof, e.g., based on those of interest to the remote UE). Alternatively, if the relay UE knows that the remote UE is directly monitoring the SI on the Uu, the relay UE may not include the modified SI. The relay UE may use similar message transmissions (such as those for monitoring paging from the Uu) to determine that the remote UE is directly monitoring the SI on the Uu, as described herein.

[0476] When such an instruction is received, the remote UE may perform one or more of the following:

[0477] a. Initiate a Uu RRC state transition (e.g., move from one Uu RRC state to another Uu RRC state).

[0478] i. For example, if the remote UE is currently in RRC_CONNECTED, the indication can be used to instruct the remote UE to transition to RRC_IDLE.

[0479] b. Initiating a trunk reselection procedure and / or initiating a PC5 connection release and / or PC5 connection establishment and / or recovery procedure with another trunk.

[0480] i. For example, a remote UE can be configured to attempt to remain in RRC_INACTIVE and can initiate a relay reselection procedure to find an alternative relay.

[0481] 1. Remote UEs may trigger relay reselection depending on the QoS and / or bearer configuration of the established bearer.

[0482] 2. The remote UE may determine whether another trunk has been selected / has been provided to trigger the establishment of a connection with another trunk.

[0483] c. Initiate cell reselection and / or recovery procedures directly via Uu.

[0484] i. Similar restrictions / conditions / actions to the above-mentioned trunk reselection can also be applied to cell reselection.

[0485] d. Temporarily suspend all relay traffic, possibly until a subsequent RRC message is received from the relay UE.

[0486] i. For example, upon receiving a CN paging request, a relay UE may send a first indication to any remote UE in the RRC_INACTIVE state. Upon receiving the first indication, the remote UE may suspend all bearers (including SRB1) to avoid initiating a recovery procedure triggered by the remote UE. Upon completion of connection establishment triggered by receiving a CN paging request, the relay UE may transmit a second indication to the remote UE. Upon receiving the second indication, the remote UE may restore all bearers (including SRB1) to re-enable the triggering of the recovery procedure by the remote UE.

[0487] Methods for relay paging on SL

[0488] The relay UE / WTRU determines the SL time window for paging transmission based on the PO and relay configuration.

[0489] In one solution, the relay UE can determine a finite time window for transmitting / relaying paging messages to one or more remote UEs. This window can be defined relative to the Uu PO associated with one or more connected remote UEs. Specifically, this window can begin at an offset from the paging frame or paging timing associated with one or more remote UEs. This window can also depend on the configuration at the relay UE.

[0490] In one option, the relay UE may determine a window (e.g., a start timeslot and duration) and send such a window to a remote UE. The relay UE may transmit window information to the remote UE via a PC5-RRC message (e.g., in a sidelink configuration message). The remote UE can use this information to determine its sidelink monitoring time. Specifically, the remote UE may be required to monitor the sidelink at least for the SL timeslot defined by the window. Alternatively, the remote UE may calculate the same window calculated by the relay UE based on the reception of configuration information (described herein) that can be sent to the remote UE by the relay and / or network. The relay UE calculation of the paging transmission window is described below. Without loss of generality, the remote UE may perform the same behavior to determine its monitoring window.

[0491] The relay UE can determine a new transmission window for relay paging messages and / or send an indication of the calculated window or changes within the calculated window to the remote UE:

[0492] a. When establishing a PC5-RRC connection with a remote UE.

[0493] b. When the calculated window changes from a previous calculation, a (pre)configured amount may be changed.

[0494] i. For example, if the remote UE changes at least X time slots, the relay UE can send a message to the remote UE.

[0495] The UE sends the calculated window, where X can be (pre)configured or predefined.

[0496] ii. For example, the change in the calculated window might be due to the start and end parameters described above for calculating the window.

[0497] This is caused by changes to any parameters related to the end and / or duration.

[0498] c. During one or each of the paging message transmission windows.

[0499] i. For example, a relay UE may transmit the calculated window or offset at each SL paging window or at each set of time slots associated with a Uu paging opportunity.

[0500] ii. For example, if the calculated window has changed by a specific amount, the relay UE may send the calculated window or offset only at the SL paging window.

[0501] After receiving and / or calculating the paging window from the relay at the remote UE, the remote UE may apply the newly calculated SL paging window at the next window time or at the next remote UE PO.

[0502] A relay UE may determine the start and / or end gap and / or duration of the paging transmission window relative to one or more connected remote UEs based on one or more of the following factors:

[0503] a. Beam mode / configuration at the relay UE.

[0504] i. For example, a relay UE can determine the initial SL timeslot as a (pre)configured number of timeslots following the first / last possible beam, on which the relay can receive paging for the remote UE in the PO of the remote UE. For example, a UE can use such an initial timeslot when configured to be in RRC_IDLE / RRC_INACTIVE.

[0505] ii. For example, a relay UE may determine the starting SL time slot as the (pre-)configured number of time slots before / after the current (optimal) beam used by the relay UE when communicating with the network.

[0506] For example, when configured to be in RRC_IDLE / RRC_INACTIVE, the UE can use such an initial time slot.

[0507] iii. For example, a relay UE may determine the starting timeslot as the (pre)configured number of timeslots before / after the first / last PDCCH monitoring timing of the PO.

[0508] iv. For example, a relay UE may determine the starting time slot based on either the pagingSearchSpaceID or the nrofPDCCH-MonitoringOccasionPerSSB-InPO RRC parameter, or any RRC parameter that defines the paging timing configuration at the relay UE.

[0509] b. Relay UE scheduling mode.

[0510] i. For example, the starting timeslot may be calculated differently depending on the scheduling mode of the relay UE. For example, the relay UE may add a first offset (e.g., the offset configured by the NW) when configured in mode 1 and a second offset (e.g., the offset determined by the UE) when configured in mode 2.

[0511] c. RRC status of the relay UE.

[0512] i. For example, the starting timeslot calculated by a relay UE in RRC_CONNECTED may be relative to the relay UE's current / optimal beam. For example, the starting timeslot calculated by a relay UE in RRC_IDLE / RRC_INACTIVE may be relative to the first / last beam in which the relay UE can receive a paging associated with a specific PO. Alternatively, the relay UE may define it based on the (pre)configured number of beams between the first and last beams.

[0513] ii. In one solution, the relay UE calculates / notifies the start point to the remote UE for both the RRC_CONNECTED and RRC_IDLE / INACTIVE scenarios, and may later indicate the current RRC state to the remote UE. The remote UE can determine the starting timeslot based on the relay UE's current RRC state.

[0514] iii. In one solution, the relay UE can calculate an offset to a previously calculated start timeslot. The relay UE can determine such an offset based on changes in the optimal / current beam measured by the relay UE. The relay UE may send the offset to the remote UE during the SL monitoring cycle. The remote UE can apply such an offset to determine the start timeslot of the next PO's SL paging cycle.

[0515] d. The number of attached remote UEs that may be associated with the same PO.

[0516] i. For example, a relay UE can configure multiple (additional) time slots in the SL paging window for each attached remote UE associated with the same PF / PO. Specifically, the relay UE can scale the size of the SL paging window based on the number of attached remote UEs associated with the PO.

[0517] e. The number of POs in paging frames that may be associated with a remote UE.

[0518] i. For example, the relay UE may configure the start time slot and / or duration of the SL paging window based on the number of POs in paging frames associated with remote UEs attached to the relay UE and / or the number of monitoring opportunities in the POs / paging frames. For example, if only one PO in the PF is associated with an attached remote UE, the relay UE may configure the start time slot to appear after one or more POs of remote UEs. Alternatively, if there are more than one PO in the PF associated with at least one remote UE attached to the relay, the relay UE may configure the start time slot to appear after the paging frame.

[0519] ii. For example, a relay UE may configure the starting timeslot at a different offset relative to the PO / PF depending on the configuration value of Ns (the number of POs configured per paging frame).

[0520] f. Sensing configuration / sensing results at the relay UE.

[0521] i. In one solution, the relay UE can calculate the starting timeslot based on sensing configuration and / or sensing results. In another solution, the relay UE can calculate the length of the SL paging window based on sensing configuration and / or sensing results.

[0522] 1. In one example, the relay UE can determine the starting timeslot based on whether the relay UE is configured with full sensing or partial sensing. Specifically, the relay UE can use a first offset from the PO for the starting timeslot when configured with full sensing, and can use a second offset from the PO for the starting timeslot when configured with partial sensing. The second offset can be determined by the partial sensing configuration. Specifically, the second offset can be determined based on the time when the UE has sufficient sensing results for transmission.

[0523] 2. In one example, a relay UE configured for full sensing can determine the starting time slot based on its UE capabilities. A relay UE configured for partial sensing can determine the starting time slot based on K.

[0524] The starting timeslot is determined by the values ​​of (the number of periods of partial sensing results to be used) and / or T_sep (the period or interval between sensing opportunities) and / or T_async (the minimum amount of sensing time required immediately before transmission). For example, the UE can be (pre)configured with the minimum required values ​​of these parameters, and the starting timeslot can be derived as the first permissible timeslot for transmission to achieve the minimum sensing results.

[0525] 3. In one example, a relay UE may calculate the length of the SL paging window based on the most recent resource selection results, where those resource selection results may be specific to the resource selection applied to the paging transmission, possibly within the SL paging transmission window associated with the PO currently having a correctly determined length for the UE, such as:

[0526] (a) The amount / percentage of resources identified as available based on resource selection.

[0527] (b) The SL RSRP threshold used to determine the required target amount of available resources to continue resource selection.

[0528] (c) The average amount of available / occupied resources determined during the resource selection period.

[0529] g. CBR measured at the relay UE.

[0530] i. For example, a trunk UE can determine the length of the SL paging window based on the measured CBR. For example, the trunk UE can be (pre-)configured with a mapping from the CBR or CBR range to the SL paging window length.

[0531] h. The priority of the LCH configured at the relay UE (e.g., for the RRC_INACTIVE scenario).

[0532] i. For example, if a trunk UE is configured with one or more trunk LCHs with higher priority, the trunk UE can be configured with an earlier start timeslot and / or a shorter SL paging window.

[0533] h. The buffer status at the relay UE, or the measurement of the relay load at the relay UE.

[0534] i. For example, a relay UE may configure the starting timeslot based on the current buffer state of the relay logical channel that may be associated with other UEs (e.g., not in IDLE / INACTIVE).

[0535] ii. For example, a relay UE may be configured with different starting timeslots and / or window durations depending on the number of remote UEs that may be in RRC_CONNECTED.

[0536] I. Relay scheduling mode (i.e., mode 1 or mode 2).

[0537] i. For example, a relay UE in Mode 1 can use NW-defined values ​​for the start time slot and / or duration. On the other hand, a relay UE in Mode 2 can define the start time slot and / or duration values ​​based on other solutions mentioned herein (e.g., sensing configuration, etc.).

[0538] The relay UE / WTRU extends the SL time window for paging transmission.

[0539] In one solution, the relay UE can extend one or more instances of the SL time window, which may be associated with a PO or PF, for paging transmissions to one or more remote UEs. Specifically, if the relay UE is unable to transmit the received paging message within the original time window, the relay UE can perform SL transmissions to one or more remote UEs to extend the duration of the SL time window used for transmission.

[0540] If a time window has expired or is about to expire and the relay UE has pending paging messages to transmit, the relay UE may trigger such a transmission. The relay UE may trigger such a transmission based on the expiration of a timer (e.g., related to the duration of the window), where no paging message has been transmitted when the timer expires. Due to congestion control, if transmission of a paging message is impossible during the window period, the relay UE may trigger such a transmission. If the relay UE performs relay selection with a first window size and the relay selection fails, the relay UE may transmit such a message. The relay UE can then perform relay selection with a second window size. Despite limitations caused by CBR, the relay UE may also perform the transmission of extended messages. The relay UE may trigger such a transmission if it misses a paging transmission at the initial paging time, due to prioritizing UL over SL. The relay UE may extend the time window by a (pre)configured amount after successful transmission of the extended message. Due to the transmission of extended messages, the relay UE can extend inactive timers associated with transmissions to one or more remote UEs.

[0541] The extended message can be any of the following transmissions:

[0542] a.SL MAC CE.

[0543] b. Dedicated / Independent SCI Messages.

[0544] c.SL RRC message.

[0545] d.SL Channel State Information (CSI) report, which may be provided proactively by a remote UE.

[0546] e. An SL wake-up signal or similar SL signal used to indicate that SL needs to be monitored at a remote UE during a specific DRX cycle (on duration).

[0547] The extended message may indicate the number of time slots that cause the window to end from the window's initial schedule or from the reception of the message. Alternatively, such a number of time slots may be (pre)configured or exchanged between UEs (e.g., during unicast link establishment / configuration).

[0548] Receiving extended messages by a remote UE can extend the expected duration of the SL paging window. For example, receiving extended messages by a remote UE can cause the remote UE to reset its inactivity timer.

[0549] The relay UE / WTRU determines whether to discard / delay paging transmissions on the SL.

[0550] In an alternative solution, if a paging transmission on the SL is not performed within the SL paging window, the relay UE may discard or delay the paging transmission on the SL. Specifically, the relay UE may be unable to perform a transmission on the SL during the SL paging window and / or may be unable to transmit an extension message. In this case, the relay UE may discard the paging message. Alternatively, the relay UE may maintain the paging message pending and transmit it during the next SL paging window that may be associated with the same Uu PO / PF. The UE may also determine whether to discard or delay the paging based on the following:

[0551] a.CBR.

[0552] b. QoS and / or SLRB configuration at the remote UE.

[0553] c. RRC status of relay and / or remote UEs.

[0554] d. The time until the next SL paging window.

[0555] Specifically, a relay UE can start a timer when initiating an SL paging transmission window. If no paging message is transmitted when the timer expires, the relay UE can discard the message or delay it until the next SL paging transmission window. If the remote UE does not have any SLRBs configured for high QoS or require paging messages to be delayed to the next window, the relay can discard the paging message.

[0556] The relay UE / WTRU uses mode 1 / mode 2 to transmit paging messages.

[0557] In Mode 2, a relay UE can trigger resource selection for transmitting paging messages on the sidelink when any of the following events occur:

[0558] a. The relay UE receives a Uu paging message in the PO associated with one or more of the remote UEs connected to the PC5-RRC.

[0559] b. The relay UE receives a Uu paging message in the PO, wherein one of the identified UEs in the paging message is for one of the remote UEs with a connected PC5-RRC connection.

[0560] c. The relay UE receives a Uu paging message in the PO and receives a paging message from the network for additional instructions to one of the remote UEs with a connected PC5-RRC connection.

[0561] i. For example, a relay UE may receive such an indication as a set of L2 IDs in an embedded paging message.

[0562] ii. For example, a relay UE may receive such an indication as a separate RRC message or MAC CE, which may be received in the same time slot, in the same PO, or at some time during the reception of the actual paging message.

[0563] iii. For example, a relay UE can receive such an indication in the DCI. For example:

[0564] 1. A relay UE may receive paging messages in the DCI that are scheduled in the PDSCH and are related to relaying, or should be considered as an indication for relaying by a UE configured for relaying.

[0565] A UE that receives a remote UE ID from the network along with a paging and / or indication can trigger a resource reselection.

[0566] a. When an active paging indication is received from the network, the PO associated with the attached remote UE is indicated to have the expected paging message.

[0567] i. Relay UEs can immediately trigger resource selection.

[0568] ii. Alternatively, the relay UE may trigger resource selection at a later time before the PO / PF or SL paging window occurs.

[0569] When resource selection is triggered, the relay UE can use the defined SL transmission window as a parameter for resource selection (e.g., T1 / T2).

[0570] In another alternative, the relay UE may trigger the transmission of SL UE assistance information upon receiving a paging from the Uu (in the PO associated with the remote UE) or upon receiving an active paging indication from the network. The relay UE may provide information related to the SL paging window (e.g., periodicity, location / offset) in the UE assistance information. The relay UE may also indicate in the UE assistance information that an SL-configured authorization (CG) is being requested for forwarding paging messages. The relay UE may further indicate in the UE assistance information the specific PF / PO for which the paging is expected to be received by the relay UE requiring relaying. This SL-configured authorization may be provided ad hocly (e.g., it may be provided for a pre-configured / predefined number of DRX cycles).

[0571] In another alternative, the relay UE may trigger a scheduling request (SR) upon receiving a paging from a Uu (in the PO associated with the remote UE) or upon receiving an active paging indication from the network. Such an SR may be dedicated to indicating the need to relay paging messages. A separate SR may be configured for paging transmission as well as for SI indication and / or PWS transmission. Alternatively, the relay UE may be configured with multiple SR resources / configurations and may select the SR configuration associated with the associated remote UE or the PF / PO of the paging message to be relayed. The relay UE may trigger such an SR if it potentially does not have an SL resource for transmitting a paging message within the SL paging transmission window. Whether the relay UE triggers an SR may depend on whether the relay UE has a sidelink grant falling within the configured paging forwarding window. If no sidelink grant exists, the relay UE may trigger an SR. Whether the relay UE triggers an SR may also depend on the type of paging received. For example, a relay UE can trigger an SR if the paging is marked as high priority, or if the paging message is a PWS indication; otherwise, a relay UE can only trigger an SR if it does not have an SL authorization within the paging forwarding window.

[0572] In another alternative, the relay UE may receive a CG or CG activation along with a Uu paging message. This can be used by a relay UE in RRC_CONNECTED mode. Such CGs can be predefined / preconfigured to make their resources appear within the SL paging transmission window.

[0573] Relay UE / WTRU uses a WUS-like signal to notify remote UE / WTRU of an upcoming paging (in SL paging). (in the call window).

[0574] In one solution, when a relay UE receives or anticipates receiving a paging message for a remote UE, a set of remote UEs, or associated with a paging event, the relay UE may transmit a wake-up signal (WUS) on the sidelink.

[0575] In one solution, a relay UE may transmit a WUS after receiving an active paging indication message from the network. Specifically, the relay UE may determine whether to transmit a WUS to one or more remote UEs based on whether the active paging indication from the network indicates that a paging message will be sent to a specific UE / PO, and the relay UE may determine whether the UE is a PC5 connected to the relay or whether the PO is associated with a relay that is a PC5 connected to the relay.

[0576] In another solution, the relay UE can transmit WUS after receiving an active paging message from the network. For example, if a paging message is received some time before the expected PO of a remote UE (e.g., for an RRC_CONNECTED relay UE), the relay UE can transmit WUS.

[0577] The remote UE can be configured with a time window for receiving WUS. Specifically, the remote UE can determine the time window based on the relay UE. Specifically, the remote UE can use a similar mechanism defined herein for determining the start of the SL transmission window, based on its own PO or the relay UE's PO, to determine the time window. The relay UE can determine the time resources for transmission of WUS relative to its own paging timing, relative to the planned reception time of an active paging indication from the network, or at some (pre)configured or predefined time resources associated with the remote UE's DRX cycle.

[0578] In another solution, the relay UE may potentially transmit a single WUS-like signal on the SL to all PC5-CONNECTED remote UEs. This signal may indicate a specific PO and / or PF expected to have active paging. It may also indicate a specific remote UE that should monitor the sidelink during the defined SL paging window to potentially receive paging. The relay UE may determine the content of the SL signal based on received active paging indications from the network. Once a WUS-like signal is received on the SL, the remote UE may determine whether to monitor the SL during the defined SL paging window associated with the PO / PF, depending on whether the WUS-like signal indicates that the PO / PF will contain a paging message.

[0579] A method for determining whether / when to forward a received paging message.

[0580] The relay UE / WTRU provides a link from the remote UE / WTRU ID to the NW.

[0581] Considering potential security issues (described herein), a method is needed for a relay / remote UE to provide a link between the remote UE ID (i.e., 5G-S-TMSI, I-RNTI) used for paging and the L2 ID used by the relay UE to address the remote UE, and a method is needed to hide the remote UE ID from the relay UE.

[0582] In one approach, a remote UE may include its source / destination L2 ID along with its connection establishment / restore (which provides a paging UEID) to the network. In this case, the network can establish a link between the IDs. When the L2 ID is changed at an upper layer (e.g., due to a UE ID refresh procedure for an L2 ID defined at an upper layer), the remote UE may further trigger such a procedure or may trigger the transmission of a UuRRC message.

[0583] In another approach, the relay UE may include the source / destination L2 ID along with the reception of any messages associated with an SL RLC channel, which is associated with signaling radio bearers (such as SRB0) transmissions of the remote UE, to the network. Specifically, the relay UE may relay any messages on an SL Radio Link Control (RLC) channel dedicated to SRB0 to the network, and may include the L2 source / destination ID associated with the unicast link (between the relay and the remote UE) in the relayed messages.

[0584] The relay UE / WTRU receives a separate UE / WTRU ID with a paging message.

[0585] In one solution, in addition to the paging message on the Uu, the relay UE may also receive a list of L2 source / destination IDs corresponding to any remote UE paged in the paging message. If the paging message received via the Uu contains at least one source / destination ID associated with a remote UE to which the relay is currently connected, the relay UE may forward the paging message on the PC5 via a unicast link. Otherwise, the relay UE may not forward the paging message, or may use broadcast / multicast to forward the paging message to all remote UEs that may be associated with that PO.

[0586] For example, a relay UE in RRC_CONNECTED state can receive a list of source / destination IDs in a dedicated RRC message that includes paging records.

[0587] For example, a list of source / destination IDs that a relay UE in RRC_IDLE / RRC_INACTIVE can receive.

[0588] a. In separate transmissions within the PO / PF of a remote UE (e.g., using a different RNTI, or using the same P-RNTI used to receive paging messages).

[0589] b. Embedded in the paging record itself.

[0590] i. For example, paging records may contain additional fields associated with the L2 source / destination ID of each UE in the paging record.

[0591] The relay UE / WTRU defines the multicast / multicast UE / WTRU ID used for SL paging transmission.

[0592] In one solution, the relay UE can use a multicast / multicast UE ID for transmitting SL paging messages. Upper layers can specifically provide (reserved) L2 IDs for this purpose. Specifically, the relay UE can be configured with a single broadcast / multicast L2 ID for transmitting paging messages. Alternatively, the relay UE can have a set of broadcast / multicast L2 IDs for transmitting paging messages, each associated with the transmission of a paging message bound to:

[0593] a. PF or PF group.

[0594] b. PO or PO group.

[0595] c.SL paging transmission window.

[0596] The value of d.UE ID mod K (e.g., K = 1024) or a similar value that can be used to derive the location of PO.

[0597] In one solution, the relay UE can be assigned a group / pool of L2 IDs and can assign an L2 ID to a specific PO when establishing a PC5-RRC connection with a remote UE. Specifically, the remote UE can provide its PO (or a value that can be used to derive the PO, such as UE ID mod k) to the relay UE during sidelink configuration after the establishment of a unicast link with the relay. Therefore, the relay UE can provide the remote UE with available L2 IDs from the L2 ID pool in similar PC5-RRC configuration signaling. Upon receiving an L2 ID, the remote UE can monitor / receive a Uu paging for the sidelink from a multicast transmission using the L2 ID as the destination L2 ID in the message. The remote UE can also determine whether the paging is for it by examining the paging message to look for a paging record (i.e., one with its I-RNTI or S-TMSI), as it does in the Uu.

[0598] In another solution, the relay / remote UE may be (pre-)configured with an L2 ID to PO mapping or PO-related information (e.g., PO index or UE ID mod k). For example, such mapping may be predefined by a table in the standard. For instance, an L2 ID may contain a portion of a PO index or a UE mod K value, allowing one or more POs or UE ID mod K to be mapped to a single L2 ID. Such a table may be provided by the network (e.g., in an SIB). Upon connection to a relay, a remote UE may begin monitoring the SL to find an L2 ID that maps to a multicast transmission containing paging. Upon connection to at least one remote UE, the relay UE may perform a transmission multicast transmission (based on PO, PO index, UEID mod K, etc.) via a relay paging message with an L2 ID associated with the paging record. The relay UE may also perform such multicast transmissions only within the SL paging window associated with the PO in which the paging is received.

[0599] The UE may use multicast transmission for paging in certain situations and may use unicast to forward paging messages in other situations. The conditions for using unicast or multicast to forward paging messages may be related to either of the following:

[0600] a. RRC status of the relay UE.

[0601] i. For example, if the relay is in RRC_CONNECTED, the relay UE can use unicast to send paging; otherwise, it can use multicast.

[0602] b. Knowledge of the L2 ID associated with paging.

[0603] i. For example, if the relay UE receives the L2 source / destination ID of the UE being paged in the paging message, the relay can use unicast to send it; otherwise, it can send it via multicast.

[0604] c. Reliability requirements for paging messages.

[0605] i. For example, high-reliability paging messages can be transmitted via unicast, and low-reliability paging messages can be transmitted via multicast. The relay UE can determine the reliability of the paging message from the following:

[0606] 1. Paging message or instruction in paging DCI.

[0607] 2. SLRBs of any remote UEs configured to be associated with paging messages.

[0608] 3. The RRC status of any remote UE associated with the paging message.

[0609] d. The measured CBR.

[0610] i. For example, if the CBR is above a threshold, the relay UE can use multicast. Otherwise, the relay UE can use unicast to forward paging messages.

[0611] e. Availability of SL authorization in the SL paging window.

[0612] i. For example, if a relay UE has sufficient SL authorization in the paging window, it can use unicast; otherwise, it can use multicast.

[0613] f. The size of the paging message, or the number of paging records in the paging message.

[0614] g. The number of remote UEs attached to the relay UE.

[0615] Relay UEs can forward paging messages via unicast or multicast, depending on whether the received paging message is associated with an SI modification / PWS notification or with the paging message itself. Specifically, a relay UE can transmit multicast / broadcast messages (using a configured L2 ID) for transmitting SI modifications and / or PWS notifications, while UE paging and / or PWS notifications and / or SI modifications can be transmitted via unicast to the specific UE being paged. A relay UE can include SI modifications and / or PWS indications to the UE in unicast and also transmit those SI modifications and / or PWS indications to all its remote UEs in multicast / broadcast. For example, if a relay UE has pending SI modifications to be transmitted, the relay UE can include the SI modifications to remote UEs in any potentially pending unicast transmissions (e.g., UE paging forwarding) and also transmit the SI modifications in multicast / broadcast at a later time. As long as at least N remote UEs (where N can be 1 or a configured value) have not received SI modification and / or modified SI, the relay UE can transmit SI modification and / or modified SI in multicast / broadcast.

[0616] After receiving an SI modification or modified SI in unicast, a remote UE can ignore any SI modification indication or modified SI received in multicast / broadcast within the same modification period.

[0617] Figure 5 An exemplary flowchart 500 depicts a relay UE / WTRU determining an allowable SL slot for relaying paging messages to one or more remote UEs associated with the same PO. In one instance, the relay UE may be in an RRC_IDLE / RRC_INACTIVE state to determine an allowable SL slot for relaying paging messages to one or more remote UEs associated with the same PO, and may broadcast the relayed paging message to all remote UEs associated with the PO during those allowable SL slots.

[0618] exist Figure 5 In the example, at 505, the relay UE receives a paging opportunity (PO) from a connected UE. In one instance, the relay UE receives a PO associated with a remote UE connected to PC5-RRC (e.g., a remote UE in PC5-RRC communication). The reception of PO information can be transmitted from either the remote UE or the NW connection.

[0619] At point 510, the relay UE can assign or configure an L2 destination ID to a connected remote UE sharing the same paging timing. Here, the UE can assign or configure an L2 destination ID for one or more remote UEs sharing the same PO (Position Point) with PC5-RRC connections. At point 515, the relay UE determines the start timeslot / offset of the sidelink paging relay cycle. Here, the relay UE can determine the start timeslot / offset of the SL (Side Link) paging relay cycle relative to the paging timing of the remote UE. This determination can be based on any one or more of the relay UE's paging search space configuration, the SSB / beam configuration configured at the relay UE for paging, and / or the relay UE's sensing / partial sensing configuration.

[0620] At point 520, the relay UE determines the duration of the SL paging relay cycle. Here, the relay UE can determine the duration based on the measured CBR. At point 525, the relay UE can send / transmit the determined start timeslot / offset and duration to the remote UE. In one instance, the remote UE is associated with a PC5-RRC message from the relay UE.

[0621] In one instance, when a paging message is received to be relayed on a given Uu PO associated with one or more remote UEs, the relay UE can perform Mode 2 resource selection to select an SL resource determined by the start timeslot / offset and duration. The relay UE can then send / transmit the received paging message on the selected resource using the L2 destination ID associated with the PO.

[0622] Figure 6 An exemplary flowchart 600 depicts how a relay UE / WTRU determines which of the paging opportunities (POs) in a particular DRX cycle to wake up or monitor during a specific NW configuration, based on an indication from a connected remote UE / WTRU and an indication of an active PO in an upcoming DRX cycle received during the relay UE / WTRU's own PO. In one instance, the relay UE / WTRU operates in the RRC_IDLE / RRC_INACTIVE state but has communication with a remote UE / WTRU or can establish or re-establish communication with a remote UE / WTRU using a PC5-RRC connection.

[0623] exist Figure 6In the example, at 605, it is assumed that the relay UE / WTRU is configured with a DRX configuration and a Paging Radio Network Temporary Identifier (P-RNTI) / associated therewith. The relay UE / WTRU can use the relay RNTI (R-RNTI) to receive active PO indications. Optionally, at 610, the relay UE / WTRU can maintain, as needed, a list of POs associated with each remote UE / WTRU connected to the relay UE / WTRU. This maintenance includes the ability to add or remove POs associated with each remote UE / WTRU having a PC5-RRC connection to the relay UE / WTRU.

[0624] At 615, the relay UE / WTRU can use R-RNTI to monitor downlink control channels (such as PDCCH) to receive an active PO indication. At 620, the relay UE / WTRU detects the presence of an active PO indication. If no active PO indication is received at 620, the relay UE / WTRU does not wake up at the PO for its current DRX cycle at 625. If a PO indication is detected at 620, the relay UE / WTRU performs a wake-up at that PO for its current DRX cycle to monitor downlink control channels (such as PDCCH) at 630. Control channel monitoring uses the relay UE / WTRU R-RNTI.

[0625] Unless otherwise explicitly stated, the procedures of the above descriptive examples and the methods described with reference to the accompanying drawings can be combined without exception. Thus, for example, the establishment or configuration of paging capabilities or DRX information can be cooperatively coupled with the reception of SI or paging information by a relay WTRU and the subsequent delivery of SI or paging information to one or more remote WTRUs. In another example of the combination of described features, the above-described message structure, delivery, reception, and timing characteristics can be combined, unless otherwise specifically exempted in this description.

[0626] Figure 7An exemplary flowchart 700 depicts a trunk WTRU handling one or both of system information changes and paging opportunities for remote WTRUs. At 705, the trunk WTRU may be configured with discontinuous reception (DRX) of one or more remote WTRUs. At 710, the trunk WTRU may receive an indication for monitoring paging opportunities (POs) for at least one of the remote WTRUs. At 715, the trunk WTRU monitors the POs and / or system information (SIs) received by the trunk WTRU for at least one of the remote WTRUs. If SI information is received, at 720, the trunk WTRU may forward the information to the relevant remote WTRU. If the trunk WTRU receives PO information for a remote WTRU at 715, at 725, the trunk WTRU may optionally provide confirmation of successful or failed reception of the PO information. Assuming successful reception of PO information for at least one remote WTRU, at 730, the trunk WTRU may then forward the paging message to the corresponding remote WTRU.

[0627] In the paging environment presented above, combinations of solution features are possible. For example, Figure 8 Method 800 is described, in which a relay UE / WTRU can forward System Information (SI) change information to a remote UE / ETRU based on an indication of the status of the remote UE / WTRU. At 805, the relay UE can receive an indication of a status change of a remote WTRU having a link with the relay UE (such as a paging-enabled PC5-RRC link). For example, the relay UE can receive an indication of a status change of the remote UE by receiving a PC5 RRC message from the remote UE. The received PC5 RRC message / signaling directly or implicitly indicates to the relay UE the RRC status or status change of the remote UE.

[0628] At point 810, the relay UE can receive a paging message from the network. The paging message may contain a System Information (SI) change indication, where the SI change indication indicates the availability of updated SI information from the network for the remote UE. The updated SI information is the actual SI information. The network can notify the relay UE of the SI information change via the indication in the paging message. The paging message from the network can be a short paging message. The updated SI information available from the network is the actual SI information, while the SI change indication is merely an indication in the paging message that the updated SI information is available from the network.

[0629] At point 815, the relay UE can transmit updated SI information to the remote UE based on a received indication of a state change from the remote UE. For example, if the received indication of a state change from the remote UE is associated with sending updated SI information to the remote UE, the relay UE transmits the updated SI information to the remote UE. In another example, if the received indication of a state change from the remote UE indicates that the remote UE has changed to an RRC idle or RRC inactive state or is currently in an RRC idle or RRC inactive state, the relay UE transmits the updated SI information to the remote UE. In an RRC idle or RRC inactive state, the remote UE relies on the relay UE to provide updated SI data.

[0630] Alternatively, if the relay UE determines that the remote UE is in RRC connected state and receives an SI change indication in a paging message, the relay UE may forward the SI change indication to the remote UE instead of forwarding the updated SI data itself. Therefore, if the received state change indication from the remote UE indicates that the remote WTRU has changed to connected state, the relay UE may transmit the SI change indication to the remote UE. In this instance (RRC connected state), the remote UE can directly obtain the updated SI data / information itself from the network.

[0631] exist Figure 9 This presents another example of a combination of the features discussed above. Figure 9 In exemplary method 900, when the remote UE is in an idle or inactive state, a system information type (such as a System Information Block (SIB) type) can be used to forward SI change information from the relay UE / WTRU to the remote UE / WTRU. At 905, the relay UE has a link with the remote UE (such as a paging-enabled PC5-RRC link). The relay UE can determine whether the remote UE is in an idle or inactive state. The state of the remote UE can be determined by monitoring its signaling. For example, the relay UE can determine the state of the remote UE via RRC messages / signaling. As expressed above, the state of the remote UE can be determined directly from RRC signaling or implicitly using, for example, PC5 RRC signaling. Figure 9At 910, the relay UE can receive a paging message from the network. The paging message may include a System Information (SI) change indication. The SI change indication indicates the availability of updated SI information from the network for the remote UE. At 915, the relay UE can forward the updated SI information to the remote UE based on one or more of the types of previous updates to SI information received by the remote UE or SI information changes. Therefore, forwarding the updated SI information to the remote WTRU is performed when one or more of the previous requests for SI information are received from the remote WTRU, or when a specific SIB is changed. In one example, when the relay UE receives an indication that an update to the SIB information previously received by the remote UE is available, the relay UE can forward the actual SI update information (obtained from the network). This forwarding is based on the selected SI information type. For example, a selected type of SIB update for the remote UE that was previously received by the remote UE may be a type of SI update that the remote UE is interested in receiving and can therefore be forwarded from the relay UE to the remote UE. In another example, a specific type of SIB (or a specific SIB) update for the remote UE may be indicated to the relay UE. One type or specific SIB update that can be forwarded from a relay UE to a remote UE is SIB1. This actual SIB information can be forwarded partially or completely by the relay UE to the remote UE. The forwarding in the above example depends on whether the remote UE is in an idle or inactive state.

[0632] exist Figure 10 This presents another example of a combination of the features discussed above. Figure 10 In exemplary method 1000, a paging message containing PWS and SI information update indications is processed by a relay UE / WTRU. Figure 10At point 1005, the relay UE / WTRU receives status information from the remote UE / WTRU. As indicated above, the relay UE can determine the status of the remote UE directly using RRC signaling, or it can determine the status of the remote UE through hints by monitoring the RRC signaling of the remote UE. At point 1010, the relay UE can receive a paging short message. The paging short message may include a PWS indication and an SI change indication. At point 1015, the relay UE determines whether the received short message contains a PWS indication. If the received paging message has a PWS indication, then at point 1025, the relay UE forwards the actual (obtained from the network) SI update information to the remote UE. If at point 1015, there is no PWS indication in the paging short message, then at point 1020, the relay UE determines whether the remote UE is in a connected state. If the remote UE is not in a connected state, such as when the remote UE is determined to be in an idle or inactive state, then at point 1025, the relay UE forwards the actual (obtained from the network) SI update information to the remote UE. If it is determined at 1020 that the remote UE is in a connected state, the relay UE can forward the received short message to the remote UE. After the positive decision at 1020, the remote UE in a connected state can obtain the updated SI information (data) from the network.

[0633] in conclusion

[0634] Although features and elements have been provided above in specific combinations, those skilled in the art will understand that each feature or element may be used alone or in any combination with other features and elements. This disclosure is not limited to the specific embodiments described in this patent application, which are intended as examples of various aspects. Many modifications and variations are possible without departing from the spirit and scope of the invention, as will be apparent to those skilled in the art. Unless expressly stated otherwise, no element, action, or description used in this specification should be construed as essential or necessary to the invention. Based on the foregoing description, functionally equivalent methods and apparatus within the scope of this disclosure, other than those listed herein, will be apparent to those skilled in the art. Such modifications and variations are intended to fall within the scope of the appended claims. This disclosure is limited only to the terms of the appended claims and the full scope of equivalents of such claimed claims. It should be understood that this disclosure is not limited to any particular method or system.

[0635] For simplicity, the aforementioned embodiments have been discussed regarding the terminology and structure of infrared-capable devices (i.e., infrared transmitters and receivers). However, the embodiments discussed are not limited to these systems, but can be applied to other systems that use other forms of electromagnetic waves or non-electromagnetic waves (such as sound waves).

[0636] It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is 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 multiple images displayed on a time basis. Similarly, 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 transmitting and / or receiving unit (WTRU); (ii) any of several embodiments of a WTRU; (iii) a device having wireless and / or wired (e.g., tetherable) capabilities configured with some or all of the structure and functions of a WTRU; (iii) a device configured with fewer than all the structure and functions of a WTRU; or (iv) etc. This document is in relation to... Figures 1A to 1D Details of exemplary WTRUs that may represent any WTRU described herein are provided. For instance, the various disclosed embodiments herein are described above and below as utilizing head-mounted displays. Those skilled in the art will recognize that devices other than head-mounted displays may be utilized, and some or all of this disclosure and the various disclosed embodiments may be modified accordingly without excessive experimentation. Examples of such other devices may include drones or other devices configured to stream information to provide an adapted, realistic experience.

[0637] Furthermore, the methods described herein can be implemented in computer programs, software, or firmware incorporated in 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 internal hard disks and removable disks), magneto-optical media, and optical media (such as CD-ROM disks and digital versatile optical discs (DVDs)). The processor associated with the software can be used to implement a radio frequency transceiver for a WTRU, UE, terminal, base station, RNC, or any host computer.

[0638] Variations of the methods, apparatus, and systems provided above are possible without departing from the scope of the invention. Given the various applicable embodiments, it should be understood that the illustrated embodiments are merely examples and should not be construed as limiting the scope of the following claims. For example, embodiments provided herein include handheld devices that may include or be used with any suitable voltage source (such as a battery) that provides any suitable voltage.

[0639] Furthermore, the embodiments provided above specify processing platforms, computing systems, controllers, and other devices including processors. 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 symbolic representations of actions and operations or instructions can be executed by various CPUs and memories. Such actions and operations or instructions may be considered as being “executed,” “computer-executed,” or “CPU-executed.”

[0640] Those skilled in the art will recognize that the actions and symbols representing operations or instructions include the CPU's manipulation of electrical signals. The electrical system represents data bits, which can lead to the final transformation or reduction of electrical signals and the retention of data bits at memory locations in the memory system, thereby reconfiguring or otherwise altering the CPU's operation and performing other signal processing. The memory location holding the data bits is a physical location having specific electrical, magnetic, optical, or organic properties corresponding to or representing the data bits. It should be understood that the implementation is not limited to the platform or CPU described above, and other platforms and CPUs may also support the provided methods.

[0641] Data bits may also be stored on a computer-readable medium, including disks, optical disks, and any other CPU-readable volatile (e.g., random access memory (“RAM”)) or non-volatile (e.g., read-only memory (“ROM”)) mass storage system. The computer-readable medium may include cooperative or interconnected computer-readable media that are uniquely present on the processing system or distributed across multiple interconnected processing systems, which may be local or remote relative to the processing system. It should be understood that the implementation is not limited to the aforementioned memory, and other platforms and memories may also support the provided methods.

[0642] In exemplary embodiments, any of the operations, processes, etc., described herein may be implemented as computer-readable instructions stored on a computer-readable medium. These computer-readable instructions may be executed by a processor of a mobile unit, network element, and / or any other computing device.

[0643] There is little difference between the hardware and software implementations of various aspects of the system. The use of hardware or software typically (but not always, as the choice between hardware and software can become important in certain contexts) represents a design choice that weighs cost against efficiency. Various media (e.g., hardware, software, and / or firmware) may exist to implement the processes and / or systems and / or other technologies described herein, and the preferred media may vary depending on the context of the deployment of the processes and / or systems 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 primarily software implementation. Alternatively, the implementer may choose some combination of hardware, software, and / or firmware.

[0644] The above detailed description has illustrated various embodiments of the apparatus and / or processes using block diagrams, flowcharts, and / or examples. Where such block diagrams, flowcharts, and / or examples include one or more functions and / or operations, those skilled in the art will understand that each function and / or operation within such block diagrams, flowcharts, or examples can be implemented individually and / or collectively by a wide range of hardware, software, firmware, or virtually any combination thereof. In embodiments, certain portions 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 integration formats. However, those skilled in the art will recognize that some aspects of the embodiments disclosed herein can be equivalently implemented in an integrated circuit, either wholly or partially, as one or more computer programs (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 virtually any combination thereof, and that designing circuits and / or writing code for software and / or firmware according to this disclosure will be entirely within the skill of those skilled in the art. Furthermore, those skilled in the art will recognize that the mechanisms of the subject matter described herein can be distributed as program products in various forms, and the exemplary embodiments of the subject matter described herein apply regardless of the specific type of signal-bearing medium used to actually implement the distribution. Examples of signal-bearing media include, but are not limited to, the following: recordable media (such as floppy disks, hard disks, CDs, DVDs, digital magnetic tapes, computer memory, etc.); and transmission media (such as digital and / or analog communication media (e.g., fiber optic cables, waveguides, wired communication links, wireless communication links, etc.)).

[0645] Those skilled in the art will recognize that it is common practice in the art to describe devices and / or processes in the manner set forth herein, and subsequently to use engineering practice to integrate such described devices and / or processes into data processing systems. That is, at least a portion of the devices and / or processes described herein can be integrated into a data processing system through a reasonable amount of experimentation. Those skilled in the art will recognize that a typical data processing system generally includes one or more of the following: a system unit enclosure; a video display device; memory, such as volatile and non-volatile memory; a processor, such as a microprocessor and a digital signal processor; computing entities, such as an operating system, drivers, a graphical user interface, and applications; one or more interactive devices, such as a touchpad or screen; and / or a control system, including feedback loops and control motors (e.g., feedback for sensing position and / or speed, control motors for moving and / or adjusting components and / or quantities). Typical data processing systems can be implemented using any suitable commercially available components, such as those commonly found in data computing / communication and / or network computing / communication systems.

[0646] The topics described herein sometimes illustrate different components included within or connected to different other components. It should be understood that such depicted architectures are merely examples, and many other architectures can in fact achieve the same functionality. Conceptually, any arrangement of components achieving the same function is effectively “associated” to enable the desired functionality. Therefore, any two components combined herein to achieve a particular function can be considered “associated” with each other to enable the desired function, regardless of the architecture or intermediate components. Similarly, any two such associated components can also be considered “operably connected” or “operably coupled” to each other to achieve the desired function, and any two components that can be suchly associated can also be considered “operably coupled” to each other to achieve the desired function. Specific examples of operably coupled components include, but are not limited to, components that can physically cooperate and / or physically interact and / or components that can wirelessly interact and / or logically interact and / or logically interact.

[0647] Regarding virtually any plural and / or singular terms used herein, those skilled in the art can appropriately convert them from plural to singular and / or from singular to plural depending on the context and / or application. For clarity, various singular / plural permutations may be explicitly listed herein.

[0648] Those skilled in the art will understand that, in general, the terminology used herein, particularly in the appended claims (e.g., the body of the appended claims), is typically intended as “open-ended” terms (e.g., the term “comprising” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “including” should be interpreted as “including but not limited to,” etc.). Those skilled in the art will also understand that if it is intended to specify a particular number of introduced claim objects, such intention will be explicitly stated in the claims, and if no such claim objects are present, such intention will not exist. For example, the term “single” or similar language may be used where only one item is anticipated. To aid understanding, the appended claims and / or the description herein may include the use of the introductory phrases “at least one” and “one or more” to introduce claim objects. However, the use of such phrases should not be construed as implying that any particular claim including such introduced claim objects is limited to an embodiment including only one such claim object by using the indefinite articles “a” or “an.” Even when the same claim includes the introductory phrase "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and / or "an" should be interpreted as meaning "at least one" or "one or more"), this is also true. The same applies to the use of definite articles used to introduce the subject matter of a claim. Furthermore, even when a specific number of the introduced subject matter of a claim is explicitly stated, those skilled in the art will recognize that such a statement should be interpreted as meaning at least the stated number (e.g., a bare statement of "two subject matters" without other modifiers means at least two subject matters, or two or more subject matters). Additionally, in instances where conventions such as "at least one of A, B, and C" are used, generally speaking, such constructions mean that those skilled in the art will understand that convention (e.g., "a system having at least one of A, B, and C" will include, but is not limited to, systems having A alone, having B alone, having C alone, having both A and B, having both A and C, having both B and C, and / or having both A, B, and C, etc.). In instances where conventions such as "at least one of A, B, or C" are used, generally speaking, such a construction implies that a person skilled in the art will understand that the convention (e.g., "a system having at least one of A, B, or C" includes, but is not limited to, systems having A alone, having B alone, having C alone, having both A and B, having both A and C, having both B and C, and / or having both A, B, and C, etc.). A person skilled in the art should also understand that, in fact, any separate 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 term, any one of the terms, or both terms.For example, the phrase “A or B” will be understood to include the possibility of “A” or “B” or “A and B”. Additionally, as used herein, the term “any one of…” followed by a list of multiple items and / or multiple item categories is intended to include items and / or item categories “any one of…”, “any combination of,” “any multiple of,” and / or “any combination of multiples of”, whether alone or in combination with other items and / or other item categories. Furthermore, as used herein, the term “group” 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. And, as used herein, the term “many” is intended to be synonymous with “multiple.”

[0649] Furthermore, where features or aspects of this disclosure are described in accordance with the Markush Group, those skilled in the art will recognize that this disclosure is also described in accordance with any individual member of the Markush Group or a subgroup of its members.

[0650] As those skilled in the art will understand, for any and all purposes (such as for providing a written description), all scopes disclosed herein also encompass any and all possible subscopes and combinations thereof. Any listed scope can be readily identified as sufficiently descriptive and such that the same scope can be divided into at least two equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each scope discussed herein can be readily divided into a lower third, a middle third, and an upper third, etc. As those skilled in the art will also understand, all language such as “at most,” “at least,” “greater than,” “less than,” etc., includes the referenced number and refers to a scope that can subsequently be divided into subscopes as described above. Finally, as those skilled in the art will understand, a scope includes each individual number. Thus, for example, a group having 1 to 3 units means a group having 1, 2, or 3 units. Similarly, a group having 1 to 5 units means a group having 1, 2, 3, 4, or 5 units, etc.

[0651] Furthermore, unless otherwise stated, the claims should not be construed as being limited to the order or elements provided.

Claims

1. A wireless transmit / receive unit (WTRU), wherein the wireless transmit / receive unit (WTRU) is a remote WTRU, and comprises: The processor is configured as follows: Receive Radio Resource Control (RRC) indication to perform a state transition from a first RRC state to a second RRC state, wherein the first RRC state is different from the second RRC state; Perform the state transition; After entering the second RRC state, a paging message is transmitted to the relay WTRU via a side link in a PC5-RRC message. This paging message includes discontinuously received DRX loop information, and the remote WTRU is configured to determine the DRX loop information to be included in the paging message based on whether the second RRC state is an RRC idle state or an RRC inactive state. When the second RRC state is the RRC inactive state, the DRX cycle information is determined to be the minimum of the following: (i) the DRX cycle configured in the non-access stratum of the remote WTRU, and (ii) the DRX cycle configured in the RRC of the remote WTRU. When the second RRC state is the RRC idle state, the DRX loop information is determined to be the DRX loop configured in the non-access stratum of the remote WTRU; and A paging change request is sent to the relay WTRU, indicating that the relay WTRU is no longer monitoring paging on behalf of the remote WTRU.

2. The WTRU of claim 1, wherein being configured to transmit paging information after entering the second RRC state includes: It is configured to transmit paging information lacking the DRX information of the remote WTRU when the second RRC state is an RRC connected state.

3. The WTRU of claim 1, wherein the remote WTRU has a PC5 RRC connection to the relay WTRU, and the relay WTRU has a connection to the network via a Uu interface.

4. The WTRU of claim 1, wherein the processor is configured to transmit a transmission including a WTRU identifier to the relay WTRU, wherein the WTRU identifier includes a radio network temporary identifier or a temporary mobile subscriber identifier.

5. The WTRU according to claim 1, wherein the first RRC state is an RRC connection state.

6. The WTRU of claim 1, wherein the RRC indication is an RRC release message.

7. The WTRU of claim 1, wherein being configured to transmit paging information to the relay WTRU after entering the second RRC state includes: It is configured to send paging information to the relay WTRU after entering the second RRC state and in response to a change in the DRX cycle.

8. The WTRU according to claim 1, wherein: The processor is configured to send paging change request information to at least one of the relay WTRU and the network; The paging change request includes information indicating a change from a first set of one or more paging times to a second set of one or more paging times; The second set of one or more paging opportunities includes one or more paging opportunities during which the remote WTRU will monitor paging information from the network via the relay WTRU; and The first set of one or more paging opportunities is not for receiving paging information from the network via the relay WTRU.

9. The WTRU according to claim 1, wherein, The processor is configured to: During one or more paging opportunities, monitor the transmission of the Physical Downlink Control Channel (PDCCH) sent from the network in the paging search space.

10. The WTRU according to claim 1, wherein, Being configured to receive RRC indications includes being configured for at least one of the following: Receive the RRC indication from the relay WTRU; In response to a paging message from the network, the RRC indication is received from the relay WTRU; Receive the RRC indication from the relay WTRU that is in an RRC inactive state; and In response to a paging message from the network, the RRC indication is received from the relay WTRU which is in an RRC inactive state.

11. A method implemented in a wireless transmit / receive unit (WTRU), wherein the WTRU is a remote WTRU, the method comprising: Receive Radio Resource Control (RRC) indication to perform a state transition from a first RRC state to a second RRC state, wherein the first RRC state is different from the second RRC state; Perform the state transition; After entering the second RRC state, paging information is transmitted to the relay WTRU via a side link. This paging information includes discontinuously received DRX loop information, and the remote WTRU is configured to determine the DRX loop information to be included in the paging information based on whether the second RRC state is an RRC idle state or an RRC inactive state. When the second RRC state is the RRC inactive state, the DRX cycle information is determined to be the minimum of the following: (i) the DRX cycle configured in the non-access stratum of the remote WTRU, and (ii) the DRX cycle configured in the RRC of the remote WTRU. When the second RRC state is the RRC idle state, the DRX loop information is determined to be the DRX loop configured in the non-access stratum of the remote WTRU; and A paging change request is sent to the relay WTRU, the paging change request indicating that the relay WTRU no longer monitors paging on behalf of the remote WTRU.

12. The method of claim 11, wherein transmitting paging information after entering the second RRC state includes: When the second RRC state is an RRC connected state, a paging message is transmitted that lacks the DRX information of the remote WTRU.

13. The method of claim 11, wherein the remote WTRU has a PC5 RRC connection to the relay WTRU, and the relay WTRU has a connection to the network via a Uu interface.

14. The method of claim 11, further comprising transmitting to the relay WTRU a transmission including a WTRU identifier, wherein the WTRU identifier includes a radio network temporary identifier or a temporary mobile subscriber identifier.

15. The method of claim 11, wherein the first RRC state is an RRC connection state.

16. The method of claim 11, wherein the RRC indication is an RRC release message.

17. The method of claim 11, wherein transmitting paging information to the relay WTRU after entering the second RRC state comprises: After entering the second RRC state and in response to the change in the DRX cycle, a paging message is sent to the relay WTRU.

18. The method of claim 11, further comprising transmitting a paging change request message to at least one of the relay WTRU and the network, wherein: The paging change request includes information indicating a change from a first set of one or more paging times to a second set of one or more paging times; The second set of one or more paging opportunities includes one or more paging opportunities during which the remote WTRU will monitor paging information from the network via the relay WTRU; and The first set of one or more paging opportunities is not for receiving paging information from the network via the relay WTRU.

19. The method of claim 11, further comprising: During one or more paging opportunities, monitor the transmission of the Physical Downlink Control Channel (PDCCH) sent from the network in the paging search space.

20. The method according to claim 11, wherein, Receiving an RRC instruction includes at least one of the following: Receive the RRC indication from the relay WTRU; In response to a paging message from the network, the RRC indication is received from the relay WTRU; Receive the RRC indication from the relay WTRU that is in an RRC inactive state; and In response to a paging message from the network, the RRC indication is received from the relay WTRU which is in an RRC inactive state.

Images