Method and apparatus for paging reception via user equipment to network relay in a wireless communication system

Abstract

Methods and apparatuses for paging reception via user equipment to network relaying are disclosed. In one embodiment, a method includes enabling a user equipment to use a layer 2 type user equipment to network relay. The method also includes the user equipment discovering one or more relay user equipments in response to being enabled to use the layer 2 type user equipment to network relay. Further, the method includes the user equipment selecting a relay user equipment from the one or more relay user equipments. Additionally, the method includes the user equipment establishing a layer 2 link with the relay user equipment. The method also includes the user equipment receiving paging information for the user equipment from the relay user equipment over the layer 2 link.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 287,756, filed December 9, 2021, and U.S. Provisional Patent Application No. 63 / 328,530, filed April 7, 2022, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to wireless communication networks, and more specifically, to methods and apparatus for receiving paging messages via user equipment (UE) to network relays in wireless communication systems. Background Technology

[0004] With the rapid growth in demand for transmitting large amounts of data to and from mobile communication devices, traditional mobile voice communication networks have evolved into networks that communicate using Internet Protocol (IP) packets. This IP packet communication can provide users of mobile communication devices with IP-bearing voice, multimedia, multicast, and video-on-demand communication services.

[0005] An exemplary network architecture is the Evolved Universal Terrestrial Radio Access Network (E-UTRAN). E-UTRAN systems can provide high data throughput to enable the aforementioned IP-based voice and multimedia services. Currently, the 3GPP standards organization is discussing next-generation radio technologies (e.g., 5G). Therefore, changes to the current core of the 3GPP standards are being submitted and considered to facilitate their evolution and completion. Summary of the Invention

[0006] A method and apparatus for receiving paging information via a UE-to-Network relay are disclosed. In one embodiment, the method includes enabling a UE to use a Layer 2 type UE-to-Network (U2N) relay. The method further includes the UE discovering one or more relay UEs in response to the ability to use a Layer 2 type U2N relay. Additionally, the method includes the UE selecting a relay UE from the one or more relay UEs. Furthermore, the method includes the UE establishing a Layer 2 link with the relay UE. The method also includes the UE receiving paging information for the UE from the relay UE via the Layer 2 link. Attached Figure Description

[0007] Figure 1 A diagram of a wireless communication system according to an exemplary embodiment is shown.

[0008] Figure 2 This is a block diagram of a transmitter system (also referred to as an access network) and a receiver system (also referred to as a user equipment or UE) according to an exemplary embodiment.

[0009] Figure 3 This is a functional block diagram of a communication system according to an exemplary embodiment.

[0010] Figure 4 This is based on an exemplary embodiment. Figure 3 Functional block diagram of the program code.

[0011] Figure 5 It is 3GPP TS 38.331 V16.6.0. Figure 5 Reproduction of .3.2.1-1.

[0012] Figure 6 It is 3GPP TS 23.304 V17.0.0. Figure 4 Reproduction of .2.7.2-1.

[0013] Figure 7 It is 3GPP TS 23.304 V17.0.0. Figure 6 Reproduction of .3.2.3.2-1.

[0014] Figure 8 It is 3GPP TS 23.304 V17.0.0. Figure 6 Reproduction of .3.2.3.3-1.

[0015] Figure 9 It is 3GPP TS 23.304 V17.0.0. Figure 6 Reproduction of .4.3.1-1.

[0016] Figure 10 It is 3GPP TS 23.304 V17.0.0. Figure 6 Reproduction of .4.3.3-1.

[0017] Figure 11 It is 3GPP TS 23.304 V17.0.0. Figure 6 Reproduction of .5.2.1-1.

[0018] Figure 12 It is 3GPP R2-2111490. Figure 5 Reproduction of .8.9.x2.1-1.

[0019] Figure 13 It is 3GPP R2-2111490. Figure 5 Reproduction of .8.9.x3.1-1.

[0020] Figure 14 This is a flowchart based on an exemplary embodiment.

[0021] Figure 15 This is a flowchart based on an exemplary embodiment.

[0022] Figure 16 This is a flowchart based on an exemplary embodiment.

[0023] Figure 17 This is a flowchart based on an exemplary embodiment.

[0024] Figure 18 This is a flowchart based on an exemplary embodiment.

[0025] Figure 19 This is a flowchart based on an exemplary embodiment.

[0026] Figure 20 This is a flowchart based on an exemplary embodiment. Detailed Implementation

[0027] The exemplary wireless communication systems and apparatus described below employ wireless communication systems that support broadcast services. Wireless communication systems are widely deployed to provide various types of communication, such as voice, data, etc. These systems may be based on Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Orthogonal Frequency Division Multiple Access (OFDMA), 3GPP Long Term Evolution (LTE) Radio Access, 3GPP Long Term Evolution Advanced (LTE-A), 3GPP2 Ultra Mobile Broadband (UMB), WiMax, 3GPP New Radio (NR), or some other modulation techniques.

[0028] Specifically, the exemplary wireless communication systems and apparatus described below may be designed to support one or more standards, such as those provided by the consortium referred to herein as 3GPP, which is named the “3rd Generation Partnership Project”, including: TS 38.331 V16.6.0, “NR; Radio Resource Control (RRC) Protocol Specification (Revision 16)”; TS 23.304 V17.0.0, “Proximity-Based Service (ProSe) in 5G Systems (5GS) (Revision 17)”; R2-2111437, “Introduction to Rel-17 Sidelink Relay”, MediaTek Inc.; R2-2111490, “Introduction to Rel-17 Sidelink Relay”, Huawei HiSilicon; and TS 38.304 V16.6.0, “NR; User Equipment (UE) Procedures in Idle Mode and RRC Inactive State (Revision 16)”. The standards and documents listed above are hereby expressly incorporated by reference in their entirety.

[0029] Figure 1 A multiple access wireless communication system according to an embodiment of the present invention is illustrated. Access network 100 (AN) includes multiple antenna groups, one antenna group comprising 104 and 106, another antenna group comprising 108 and 110, and yet another antenna group comprising 112 and 114. Figure 1 In this diagram, only two antennas are shown for each antenna group, but each antenna group can utilize more or fewer antennas. Access terminal 116 (AT) communicates with antennas 112 and 114, where antennas 112 and 114 transmit information to access terminal 116 via forward link 120 and receive information from access terminal 116 via reverse link 118. Access terminal 122 (AT) communicates with antennas 106 and 108, where antennas 106 and 108 transmit information to access terminal 122 via forward link 126 and receive information from access terminal 122 via reverse link 124. In an FDD system, communication links 118, 120, 124, and 126 can use different frequencies for communication. For example, forward link 120 can use a frequency different from that used by reverse link 118.

[0030] Each group of antennas and / or the area in which they are designed to communicate is often referred to as a sector of the access network. In an embodiment, each antenna group is designed to communicate with an access terminal in a sector of the area covered by access network 100.

[0031] In communications via forward links 120 and 126, the transmit antennas of access network 100 can utilize beamforming to improve the signal-to-noise ratio of the forward links for different access terminals 116 and 122. Furthermore, compared to an access network that transmits to all its access terminals via a single antenna, the access network using beamforming to transmit to access terminals randomly distributed throughout its coverage area causes less interference to access terminals in neighboring cells.

[0032] An access network (AN) can be a fixed station or base station used for communication with terminals, and may also be referred to as an access point, Node B, base station, enhanced base station, evolved Node B (eNB), network node, network, or other terminology. An access terminal (AT) may also be referred to as a user equipment (UE), wireless communication device, terminal, access terminal, or other terminology.

[0033] Figure 2 This is a simplified block diagram of an embodiment of the transmitter system 210 (also referred to as the access network) and receiver system 250 (also referred to as the access terminal (AT) or user equipment (UE)) in the MIMO system 200. At the transmitter system 210, service data for multiple data streams is provided from the data source 212 to the transport (TX) data processor 214.

[0034] In one embodiment, each data stream is transmitted via a corresponding transmit antenna. The TX data processor 214 formats, decodes, and interleaves the service data of the data streams based on a specific decoding scheme selected for each data stream to provide decoded data.

[0035] OFDM technology can be used to multiplex the decoded data and pilot data of each data stream. The pilot data is typically a known data pattern processed in a known manner and can be used at the receiver system to estimate the channel response. The multiplexed pilot and decoded data for said data streams are then modulated (i.e., symbol mapped) based on a specific modulation scheme (e.g., BPSK, QPSK, M-PSK, or M-QAM) selected for each data stream to provide modulated symbols. Instructions executed by processor 230 determine the data rate, decoding, and modulation for each data stream.

[0036] The modulation symbols of all data streams are then provided to a TX MIMO processor 220, which can further process the modulation symbols (e.g., for OFDM). The TX MIMO processor 220 then provides NT modulation symbol streams to NT transmitters (TMTRs) 222a to 222t. In some embodiments, the TX MIMO processor 220 applies beamforming weights to the symbols of the data streams and the antennas from which the symbols are transmitted.

[0037] Each transmitter 222 receives and processes a corresponding symbol stream to provide one or more analog signals, and further modulates (e.g., amplifies, filters, and upconverts) the analog signals to provide modulated signals suitable for transmission via a MIMO channel. NT modulated signals from transmitters 222a to 222t are then transmitted from NT antennas 224a to 224t respectively.

[0038] At receiver system 250, the transmitted modulated signal is received by NR antennas 252a to 252r, and the signal received from each antenna 252 is provided to the corresponding receiver (RCVR) 254a to 254r. Each receiver 254 modulates (e.g., filters, amplifies, and down-converts) the corresponding received signal, digitizes the modulated signal to provide a sample, and further processes the sample to provide the corresponding "received" symbol stream.

[0039] The RX data processor 260 then receives and processes NR received symbol streams from NR receivers 254 based on specific receiver processing techniques to provide NT "detected" symbol streams. The RX data processor 260 then demodulates, deinterleaves, and decodes each detected symbol stream to recover the service data used for the data stream. The processing performed by the RX data processor 260 complements the processing performed by the TX MIMO processor 220 and TX data processor 214 at the transmitter system 210.

[0040] Processor 270 periodically determines which pre-decoding matrix to use (discussed below). Processor 270 formulates a reverse link message including the matrix index portion and the rank portion.

[0041] The reverse link message may include various types of information about the communication link and / or the received data stream. The reverse link message is then processed by the TX data processor 238 (which also receives service data from several data streams from the data source 236), modulated by the modulator 280, regulated by the transmitters 254a to 254r, and transmitted back to the transmitter system 210.

[0042] At transmitter system 210, the modulated signal from receiver system 250 is received by antenna 224, conditioned by receiver 222, demodulated by demodulator 240, and processed by RX data processor 242 to extract the reverse link message transmitted through receiver system 250. Next, processor 230 determines which pre-decoding matrix to use to determine beamforming weights and then processes the extracted message.

[0043] Go to Figure 3 This figure illustrates an alternative simplified functional block diagram of a communication device according to an embodiment of the present invention. Figure 3 As shown, the communication device 300 in the wireless communication system can be used to achieve... Figure 1 UE (or AT) 116 and 122 or Figure 1 The communication device 300 is a base station (or AN) 100, and the wireless communication system is preferably an NR system. The communication device 300 may include an input device 302, an output device 304, a control circuit 306, a central processing unit (CPU) 308, a memory 310, program code 312, and a transceiver 314. The control circuit 306 executes the program code 312 in the memory 310 via the CPU 308, thereby controlling the operation of the communication device 300. The communication device 300 can receive signals input by a user via the input device 302 (e.g., a keyboard or keypad) and can output images and sounds via the output device 304 (e.g., a monitor or speaker). The transceiver 314 is used to receive and transmit wireless signals, pass received signals to the control circuit 306, and wirelessly output signals generated by the control circuit 306. Alternatively, the communication device 300 in a wireless communication system can also be used. Figure 1 AN 100 in the middle.

[0044] Figure 4 According to an embodiment of the present invention Figure 3 The diagram shows a simplified block diagram of program code 312. In this embodiment, program code 312 includes an application layer 400, a layer 3 portion 402, and a layer 2 portion 404, and is coupled to a layer 1 portion 406. Layer 3 portion 402 typically performs radio resource control. Layer 2 portion 404 typically performs link control. Layer 1 portion 406 typically performs physical connections.

[0045] 3GPP TS 38.331 specifies the following paging procedure for NR version 16:

[0046] 5.3.2 Paging

[0047] 5.3.2.1 General Provisions

[0048] The name of 3GPP TS 38.331 V16.6.0 is "Paging". Figure 5 .3.2.1-1 is reproduced as Figure 5 ]

[0049] The purpose of this program is:

[0050] - Paging information is transmitted to the UE under RRC_IDLE or RRC_INACTIVE.

[0051] 5.3.2.2 Initiating

[0052] The network initiates a paging procedure by transmitting a paging message at the paging time specified in TS 38.304

[20] . The network can process multiple UEs within a paging message by including a PagingRecord for each UE.

[0053] 5.3.2.3 UE Reception of Paging Messages

[0054] Upon receiving a paging message, the UE should:

[0055] 1> If in RRC_IDLE, then for each PagingRecord contained in the paging message (if it exists):

[0056] 2> If the ue-Identity contained in PagingRecord matches the UE identity assigned by the upper layer:

[0057] 3> Forward ue-Identity and accessType (if they exist) to the upper layer;

[0058] 1> If in RRC_INACTIVE, then for each PagingRecord contained in the paging message (if it exists):

[0059] 2> If the ue-Identity contained in PagingRecord matches the UE's stored fullI-RNTI:

[0060] 3> If the UE is configured by the upper layer to have access identity 1:

[0061] 4> Initiate the RRC connection recovery procedure according to 5.3.13, where resumeCause is set to mps-PriorityAccess;

[0062] 3> Otherwise, if the UE is configured by the upper layer to have access identity 2:

[0063] 4> Initiate the RRC connection recovery procedure according to 5.3.13, where resumeCause is set to mcs-PriorityAccess;

[0064] 3> Otherwise, if the UE is configured by the upper layer to have one or more access identities equal to 11-15:

[0065] 4> Initiate the RRC connection recovery procedure according to 5.3.13, where resumeCause is set to highPriorityAccess;

[0066] 3> Otherwise:

[0067] 4> Initiate the RRC connection recovery procedure according to 5.3.13, where resumeCause is set to mt-Access;

[0068] 2> Otherwise, if the ue-Identity contained in the PagingRecord matches the UE identity assigned by the upper layer:

[0069] 3> Forward ue-Identity to the upper layer and forward accessType (if it exists) to the upper layer;

[0070] 3> Execute the action after the release reason 'Other' is switched to RRC_IDLE as specified in 5.3.11.

[0071] 3GPP TS 23.304 specifies the following procedures to support UE-to-network relay for NR version 17:

[0072] 4.2.7 5G ProSe UE to Network Relay Reference Architecture

[0073] [...]

[0074] 4.2.7.2 5G ProSe Layer 2 UE to Network Relay Reference Architecture

[0075] Figure 4 .2.7.2-1 illustrates a reference architecture for 5G ProSe Layer 2 UE to network relay. 5G ProSe Layer 2 remote UEs and 5G ProSe Layer 2 UE to network relays may be served by the same or different PLMNs. If the serving PLMNs for 5G ProSe Layer 2 remote UEs and 5G ProSe Layer 2 UE to network relays are different, then the NG-RAN is shared by the serving PLMN, see the 5G MOCN architecture in Clause 5.18 of TS 23.501 [4].

[0076] The name of 3GPP TS 23.304 V17.0.0 is "5G ProSe Layer 2 UE to Network Relay Reference Architecture". Figure 4 .2.7.2-1 was reproduced as Figure 6 ]

[0077] Note 1: The Uu between the 5G ProSe layer 2 remote UE and NG-RAN consists of RRC, SDAP and PDCP.

[0078] Note 2: 5G ProSe Layer 2 remote UEs and 5G ProSe Layer 2 UE-to-network relays are served by the same NG-RAN. The core network entities (e.g., AMF, SMF, UPF) serving 5G ProSe Layer 2 remote UEs and 5G ProSe Layer 2 UE-to-network relays may be the same or different.

[0079] [...]

[0080] 4.3.9 5G ProSe UE to Network Relay

[0081] 4.3.9.1 General Provisions

[0082] Both 5G ProSe Layer 2 and Layer 3 UE-to-network relay entities provide relay functionality to support network connectivity for 5G ProSe remote UEs. This can be used for public security services and commercial services (e.g., interactive services).

[0083] Both 5G ProSe Layer 2 and Layer 3 UE-to-network relays support the following functions to enable connectivity to the network:

[0084] - 5G ProSe UE to network relay discovery service as defined in Clause 6.3.2.3, to allow discovery by 5G ProSe remote UE;

[0085] - As a UE accessing 5GS, as defined in TS 23.501 [4], with enhancements as specified in Clauses 6.2 and 6.6;

[0086] - Relay unicast services (uplink and downlink) between 5G ProSe remote UEs and the network, thereby supporting IP, Ethernet or unstructured service types.

[0087] Note: Relaying MBS services from a 5G ProSe UE to a 5G ProSe remote UE via network relay is not supported in this version of the specification.

[0088] 4.3.9.2 5G ProSe Layer 3 UE to Network Relay

[0089] In addition to the common 5G ProSe UE-to-network relay functions defined in Clause 4.3.9.1, 5G ProSe Layer 3 UE-to-network relay also supports the following functions to enable connectivity to the network:

[0090] - 5G ProSe direct communication via 5G ProSe layer 3 UE to network relay as specified in Clause 6.5.1, for communication with 5G ProSe layer 3 remote UE for relay operation;

[0091] - End-to-end QoS processing for services used by a 5G ProSe Layer 3 remote UE when there is no N3IWF as defined in Clause 5.6.2.1 and when access is made via N3IWF Clause 5.6.2.2;

[0092] - IP address management for 5G ProSe Layer 3 remote UEs using IP service types, as defined in Clause 5.5.1.3.

[0093] 4.3.9.3 5G ProSe Layer 2 UE to Network Relay

[0094] In addition to the common 5G ProSe UE-to-network relay functions defined in Clause 4.3.9.1, 5G ProSe Layer 2 UE-to-network relay also supports the following functions to enable connectivity to the network:

[0095] - 5G ProSe direct communication via 5G ProSe layer 2 UE to network relay as specified in Clause 6.5.2, for communication with 5G ProSe layer 2 remote UE for relay operation, including end-to-end QoS processing.

[0096] - QoS handling for 5G ProSe Layer 2 UE to network relay as defined in Clause 5.6.2.3.

[0097] [...]

[0098] 5.1.4.1 Policy / Parameter Provision for 5G ProSe UE-to-Network Relay

[0099] The following information is provided in the UE to support UEs that assume the role of 5G ProSe UE-to-network relay:

[0100] 1) Authorization policy for 5G ProSe Layer 3 and / or Layer 2 UEs to network relay when "served by NG-RAN":

[0101] - The UE is authorized to relay services for 5G ProSe Layer 3 and / or Layer 2 remote UEs via a PLMN.

[0102] 2) ProSe relay discovery policy / parameters for 5G ProSe UE-to-network relay:

[0103] - When provided by the PCF, supplied in the ME, or configured in the UICC, it includes parameters that enable the UE to perform 5G ProSe UE-to-network relay discovery:

[0104] - 5G ProSe UE to Network Relay Discovery Parameters (User Information ID, Relay Service Code, UE to Network Relay Layer Indicator); The UE to Network Relay Layer Indicator indicates whether a specific RSC provides 5G ProSe Layer 2 or Layer 3 UE to Network Relay service.

[0105] - Preset destination layer 2 ID for initial signaling used to send and receive discovery messages;

[0106] - For 5G ProSe Layer 3 UE to network relay, the PDU session parameters (PDU session type, DNN, SSC mode, S-NSSAI, access type preference) will be used for the relay service of each ProSe relay service code.

[0107] - Includes security-related content for 5G ProSe relay UE to network discovery for each ProSe relay service code.

[0108] Editor's Note: Whether PCF can provide safety parameters and the details of those parameters will be determined by SA3 WG.

[0109] Note 1: 5G ProSe relay discovery policies / parameters can be provided from the ProSe application server to the 5G ProSe UE to the network relay.

[0110] 3) QoS mapping for 5G ProSe Layer 3 UE to network relay:

[0111] - Each QoS mapping entry contains:

[0112] - Mapping between 5QI and PQI values;

[0113] - PQI PDB adjustment factor for PC5 communication for 5G ProSe layer 3 UE to network relay operation;

[0114] - Optional relay service codes are associated with QoS mapping entries.

[0115] 4) For 5G ProSe Layer 3 UEs relaying Ethernet or unstructured services from 5G ProSe Layer 3 remote UEs using IP-type PDU sessions to network relay,

[0116] - Map the ProSe service to the ProSe application server address information (consisting of IP address / FQDN and transport layer port number).

[0117] The following information is provided in the UE to support the UE acting as a 5G ProSe remote UE, thereby enabling the use of 5G ProSe UE to network relay:

[0118] 1) Licensing policies for using 5G ProSe Layer 3 and / or Layer 2 UEs to relay to the network:

[0119] - Indicates whether the UE is authorized to use 5G ProSe Layer 3 and / or Layer 2 UE to network relay.

[0120] 2) Policies / parameters for 5G ProSe UE-to-network relay discovery:

[0121] - When provided by the PCF, supplied in the ME, or configured in the UICC, include parameters for 5G ProSe relay discovery and for enabling the UE to connect to the 5G ProSe UE-to-network relay after discovery:

[0122] - 5G ProSe UE to Network Relay Discovery Parameters (User Information ID, Relay Service Code, UE to Network Relay Layer Indicator); The UE to Network Relay Layer Indicator indicates whether a specific RSC provides 5G ProSe Layer 2 or Layer 3 UE to Network Relay service.

[0123] - Preset destination layer 2 ID for initial signaling used to send and receive discovery messages;

[0124] - For 5G ProSe Layer 3 UE to network relay, without using N3IWF access, the PDU session parameters (PDU session type, DNN, SSC mode, S-NSSAI, access type preference) used for relay services, or the indication of N3IWF access, will be used for each ProSe relay service code.

[0125] - Contains security-related content for 5G ProSe UE-to-network relay discovery for each ProSe relay service code.

[0126] 3) Policies / parameters for N3IWF selection for 5G ProSe Layer 3 remote UEs:

[0127] - N3IWF identifier configuration (FQDN or IP address) for 5G ProSe Layer 3 remote UE in HPLMN.

[0128] - 5G ProSe Layer 3 UE to Network Relay Access Node Selection Information - A priority list of PLMNs used for N3IWF selection. It also indicates whether the selection of the N3IWF in the PLMN should be based on the Tracking Area Identity FQDN or the Carrier Identifier FQDN.

[0129] Editor's Note: Whether PCF can provide safety parameters and the details of those parameters will be determined by SA3 WG.

[0130] Note 2: ProSe relay discovery policies / parameters can be provided from the ProSe application server to the 5G ProSe remote UE.

[0131] The following information is provided in the UE to support UEs acting as 5G ProSe UE-to-network relays, and the following information is provided in the UE to support UEs acting as 5G ProSe remote UEs, thereby enabling the use of 5G ProSe UE-to-network relays:

[0132] 1) Radio parameters used for 5G ProSe UE-to-network relay discovery when the UE is not "served by NG-RAN":

[0133] - Includes radio parameters for the NR PC5 with a geographic region, and an indication of whether the radio parameters are "carrier-managed" or "non-carrier-managed". The UE uses the radio parameters to perform 5G ProSe direct discovery via the PC5 reference point only when it can reliably locate itself in the corresponding geographic region, in the case of "not served by NG-RAN". Otherwise, the UE is not authorized to transmit.

[0134] 2) Radio parameters used for 5G ProSe relay UE-to-network communication when the UE is not "served by NG-RAN":

[0135] - Includes radio parameters for the NR PC5 with a geographic area, and an indication of whether the radio parameters are "carrier-managed" or "non-carrier-managed". The UE uses the radio parameters to perform 5G ProSe direct communication via the PC5 reference point only when it can reliably locate itself in the corresponding geographic area, in the case of "not served by NG-RAN". Otherwise, the UE is not authorized to transmit.

[0136] [...]

[0137] 5.8.3 Identifiers used for 5G ProSe UE-to-network relay

[0138] 5.8.3.1 Commonly Used Identifiers for 5G ProSe UE-to-Network Relay

[0139] The following parameters are used in the 5G ProSe UE-to-network relay discovery notification message (Model A), where the source layer 2 ID and destination layer 2 ID are used to send and receive messages, and the notifier information and relay service code are included in the message:

[0140] - Source Layer 2 ID: The source layer 2 ID that the 5G ProSe UE to network relay chooses for 5G ProSe UE to network relay discovery.

[0141] - Destination Layer 2 ID: The destination layer 2 ID selected based on the configuration described in Clause 5.1.4.1 for 5G ProSe UE to network relay discovery.

[0142] - Notifier Information: Provides information about the user being notified.

[0143] - Relay Service Code: A parameter identifying the connectivity services provided by the 5G ProSe UE-to-Network Relay to the 5G ProSe remote UE. The Relay Service Code is configured in the 5G ProSe UE-to-Network Relay for announcement purposes. Additionally, the Relay Service Code can also identify the authorized users to whom the 5G ProSe UE-to-Network Relay will provide services, and can be used to select, for example, relevant security policies or information necessary for authentication and authorization between the 5G ProSe remote UE and the 5G ProSe UE-to-Network Relay (e.g., the Relay Service Code for a relay used only by the police will differ from the Relay Service Code for a relay used only by firefighters, even if they may provide connectivity to the same DN to, for example, support Internet access).

[0144] The following parameters are used in the 5G ProSe UE-to-network relay discovery request message (Model B), where the source layer 2 ID and destination layer 2 ID are used to send and receive messages, and the discoverer information and relay service code are included in the message:

[0145] - Source Layer 2 ID: The source layer 2 ID that the 5G ProSe remote UE selects for 5G ProSe UE to network relay discovery.

[0146] - Destination Layer 2 ID: The destination layer 2 ID selected based on the configuration described in Clause 5.1.4.1 for 5G ProSe UE to network relay discovery.

[0147] - Discoverer Information: Provides information about the discoverer user.

[0148] - Relay Service Code: Information about connectivity that the discovering UE is interested in. The relay service code is configured in 5G ProSe remote UEs that are interested in the relevant connectivity services.

[0149] The following parameters are used in the 5G ProSe UE to network relay discovery response message (Model B), where the source layer 2 ID and destination layer 2 ID are used to send and receive messages, and the discoverer information and relay service code are included in the message:

[0150] - Source Layer 2 ID: The source layer 2 ID that the 5G ProSe UE to network relay chooses for 5G ProSe UE to network relay discovery.

[0151] - Destination Layer 2 ID: Set to the source Layer 2 ID of the received 5G ProSe UE to network relay discovery request message.

[0152] - Relay Service Code: Identifies the connectivity service provided by the network relay from the 5G ProSe UE to the 5G ProSe remote UE, which matches the relay service code from the corresponding discovery request message.

[0153] - Discoverer Information: Provides information about the person who was discovered.

[0154] [...]

[0155] 6.3.2.3 5G ProSe UE to Network Relay Discovery

[0156] 6.3.2.3.1 General Provisions

[0157] 5G ProSe UE-to-Network Relay Discovery applies to both 5G ProSe Layer 3 and Layer 2 UE-to-Network Relay Discovery for public safety use and commercial services. To perform 5G ProSe UE-to-Network Relay Discovery, the 5G ProSe Remote UE and the 5G ProSe UE-to-Network Relay are pre-configured or supplied with the relevant information as described in Clause 5.1.

[0158] In 5G ProSe UE-to-network relay discovery, the UE uses pre-configured or supplied information for the relay discovery procedure as defined in Clause 5.1.4.1.

[0159] Relay Service Codes (RSCs) are used for 5G ProSe UE-to-Network Relay discovery to indicate the connectivity services provided by the 5G ProSe UE-to-Network Relay to the 5G ProSe Remote UE. A PSC is configured on the 5G ProSe UE-to-Network Relay and the 5G ProSe Remote UE as defined in Clause 5.1.4. The 5G ProSe UE-to-Network Relay and the 5G ProSe Remote UE know whether the RSC is providing 5G ProSe Layer 2 or Layer 3 UE-to-Network Relay services based on the policy specified in Clause 5.1.4. 5G ProSe UE-to-Network Relays supporting multiple RSCs can advertise the RSC using multiple discovery messages, one RSC per discovery message.

[0160] A separate discovery message of type “Relay Discovery Additional Information” can be used to announce additional information for 5G ProSe UE to network relay (re)selection and connection maintenance. This may include, for example, relevant system information about the serving cell of the 5G ProSe UE to network relay, as defined in TS 38.300

[12] .

[0161] Both Model A and Model B support the discovery of both:

[0162] Model A uses a single discovery protocol message (notification).

[0163] Model B uses two discovery protocol messages (request and response).

[0164] For additional information about relay discovery, only Model A is used for discovery.

[0165] 6.3.2.3.2 Procedure for 5G ProSe UE to Network Relay Discovery using Model A

[0166] Figure 6 Section 3.2.3.2-1 describes the procedure for 5G ProSe UE to network discovery using Model A.

[0167] The 3GPP TS 23.304 V17.0.0 is titled "5G ProSe UE to Network Relay Discovery Using Model A". Figure 6 .3.2.3.2-1 is reproduced as Figure 7 ]

[0168] 1. 5G ProSe UE-to-Network Relay Transmission of UE-to-Network Relay Discovery Notification Message. The UE-to-Network Relay Discovery Notification Message contains the type of discovery message, the notifier information, and the RSC, and is transmitted using the source layer 2 ID and the destination layer 2 ID, as described in Clause 5.8.3.

[0169] For 5G ProSe Layer 3 UE to Network Relay, when the S-NSSAI associated with the RSC is an allowed NSSAI for UE to Network Relay, 5G ProSe Layer 3 UE to Network Relay should only include the RSC in the UE to Network Relay discovery notification.

[0170] The 5G ProSe remote UEs (1 to 3) determine the destination layer 2 ID for signaling reception. Configure the destination layer 2 ID for the UE as specified in Clause 5.1.4.1.

[0171] 5G ProSe remote UEs (1 to 3) listen for notification messages from 5G ProSe UEs to the network RSC corresponding to the desired service.

[0172] Optionally, the 5G ProSe UE to Network Relay can also send a UE to Network Relay Discovery Additional Information message. The parameters contained in this message are described in Clause 5.8.3.

[0173] The 5G ProSe remote UE selects a 5G ProSe UE to the network relay based on the information received in step 1.

[0174] Note: Access layer information used for 5G ProSe UE-to-network relay selection is specified in the RAN specification.

[0175] 6.3.2.3.3 Procedure for 5G ProSe UE to Network Relay Discovery using Model B

[0176] Figure 6 Section 3.2.3.3-1 describes the procedure for 5G ProSe UE to network relay discovery using Model B.

[0177] The 3GPP TS 23.304 V17.0.0 is titled "5G ProSe UE to Network Relay Discovery Using Model B". Figure 6 .3.2.3.3-1 is reproduced as Figure 8 ]

[0178] 1. The 5G ProSe remote UE sends a 5G ProSe UE to Network Relay Discovery Request Message. The 5G ProSe UE to Network Relay Discovery Request Message contains the discovery message type, discoverer information, and RSC, and is sent using the source Layer 2 ID and destination Layer 2 ID, as described in Clause 5.8.3. The 5G ProSe remote UE discovering the 5G ProSe UE to Network Relay sends the request message with an RSC associated with the desired connectivity service. The RSC is based on the policy / parameters specified in Clause 5.1.4.1.

[0179] Clause 5.8.3 specifies the method by which the 5G ProSe UE determines the destination Layer 2 ID for signaling reception via network relays (1 to 3). As specified in Clause 5.1.4.1, the destination Layer 2 ID is configured for the UE.

[0180] 2. The 5G ProSe UE to Network Relay (1 and 2) that match the RSC value contained in the request message respond to the 5G ProSe remote UE using a UE to Network Relay discovery response message. The 5G ProSe UE to Network Relay discovery response message contains the type of discovery message, the discoverer information, and the RSC, and is sent using the source layer 2 ID and the destination layer 2 ID, as described in Clause 5.8.3.

[0181] For 5G ProSe Layer 3 UE to network relay, when the S-NSSAI associated with the RSC is an allowed NSSAI for 5G ProSe UE to network relay, 5G ProSe UE to network relay should only respond to the matching RSC in the UE to network relay discovery request message.

[0182] The 5G ProSe remote UE selects a 5G ProSe UE to the network relay based on the information received in step 2.

[0183] 6.4 5G ProSe direct communication

[0184] [...]

[0185] 6.4.3 Unicast Mode 5G ProSe Direct Communication

[0186] 6.4.3.1 Establishing a Layer 2 Link via the PC5 Reference Point

[0187] In order to perform unicast mode of ProSe direct communication via the PC5 reference point, the UE is configured with the relevant information as described in Clause 5.1.3.

[0188] Figure 6 4.3.1-1 illustrates the Layer 2 link establishment procedure for ProSe direct communication in unicast mode via the PC5 reference point.

[0189] The 3GPP TS 23.304 V17.0.0 is named "Layer 2 Link Establishment Procedure". Figure 6 .4.3.1-1 is reproduced as Figure 9 ]

[0190] 1. As specified in Clause 5.8.2.4, the UE determines the destination layer 2 ID for signaling reception used for PC5 unicast link establishment.

[0191] 2. The ProSe application layer in UE-1 provides application information for PC5 unicast communication. This application information includes ProSe service information and the UE's application layer ID. The application information may include the target UE's application layer ID.

[0192] The ProSe application layer in UE-1 can provide the ProSe application requirements for this unicast communication. As specified in Clause 5.6.1, UE-1 determines the PC5 QoS parameters and PFI.

[0193] If UE-1 decides to reuse an existing PC5 unicast link as specified in Clause 5.3.4, then the UE triggers the Layer 2 link modification procedure as specified in Clause 6.4.3.4.

[0194] 3. UE-1 sends a Direct Communication Request message to initiate a unicast Layer 2 link establishment procedure. The Direct Communication Request message includes:

[0195] - Source user information: Application layer ID of the initiating UE (i.e., the application layer ID of UE-1).

[0196] - If the ProSe application layer provides the target UE's application layer ID in step 2, then the following information is included:

[0197] - Target user information: The application layer ID of the target UE (i.e., the application layer ID of UE-2).

[0198] - ProSe service information: Information about the ProSe identifier used to establish the request layer 2 link.

[0199] - Security information: Information used to establish security.

[0200] Note 1: Security information and the necessary protection of source user information and target user information are defined by SA WG3.

[0201] As specified in Clauses 5.8.2.1 and 5.8.2.4, determine the source Layer 2 ID and destination Layer 2 ID used to send the direct communication request message. The destination Layer 2 ID can be a broadcast or unicast Layer 2 ID. When using a unicast Layer 2 ID, the target user information should be included in the direct communication request message.

[0202] UE-1 sends direct communication request messages by broadcasting or unicasting PC5 using source layer 2 ID and destination layer 2 ID.

[0203] 4. Establish UE-1's security as follows:

[0204] 4a. If the target user information is included in the direct communication request message, the target UE (i.e., UE-2) responds by establishing security with UE-1.

[0205] 4b. If the target user information is not included in the direct communication request message, then UEs interested in using the ProSe service through the PC5 unicast link with UE-1 respond by establishing security with UE-1.

[0206] Note 2: Signaling used for security procedures is defined by SA WG3.

[0207] When security protection is enabled, UE-1 sends the following information to the target UE:

[0208] - If IP communication is used, then:

[0209] - IP address configuration: For IP communication, this link requires an IP address configuration, which indicates one of the following values:

[0210] - "DHCPv4 server", which acts as a DHCPv4 server if only the IPv4 address allocation mechanism is supported by the initiating UE; or

[0211] - "IPv6 router", which acts as an IPv6 router if only the IPv6 address allocation mechanism is supported by the initiating UE; or

[0212] - "DHCPv4 server and IPv6 router", if both IPv4 and IPv6 address allocation mechanisms are supported by the initiating UE; or

[0213] - "Address allocation not supported" if neither the IPv4 nor IPv6 address allocation mechanism is supported by the initiating UE.

[0214] - Link-local IPv6 address: If the UE-1 does not support the IPv6 IP address allocation mechanism, i.e., the IP address configuration indicates "address allocation is not supported", then a link-local IPv6 address is formed locally based on RFC 4862

[17] .

[0215] - QoS Information: Information about one or more PC5 QoS flows. For each PC5 QoS flow, the PFI and corresponding PC5 QoS parameters (i.e., PQI and conditionally other parameters such as MFBR / GFBR) and the associated ProSe identifier.

[0216] As specified in Clauses 5.8.2.1 and 5.8.2.4, determine the source Layer 2 ID used for the security establishment procedure. The destination Layer 2 ID is set to the source Layer 2 ID of the received direct communication request message.

[0217] Once a security establishment procedure message is received, UE-1 obtains the Layer 2 ID of the peer UE for signaling and data services used for this unicast link for future communication.

[0218] 5. One or more target UEs that have successfully established security with UE-1 will directly communicate to receive messages sent to UE-1:

[0219] 5a. (Layer 2 Link Establishment for UE) If the direct communication request message contains target user information, then in the case of application layer ID matching for UE-2, the target UE (i.e., UE-2) responds with a direct communication accept message.

[0220] 5b. (Layer 2 Link Establishment for ProSe Services) If the direct communication request message does not contain target user information, then the UE interested in using the ProSe service (as per 3GPP TS 23.304V17.0.0) will... Figure 6 UE-2 and UE-4 in .4.3.1-1 respond to requests by sending a direct communication accept message.

[0221] Direct communication message reception includes:

[0222] - Source User Information: The application layer ID of the UE that sent the direct communication message.

[0223] - QoS Information: Information about one or more PC5 QoS flows. For each PC5 QoS flow, the PFI requested by UE-1 and the corresponding PC5 QoS parameters (i.e., PQI and conditionally other parameters such as MFBR / GFBR) and the associated ProSe identifier.

[0224] - If IP communication is used, then:

[0225] - IP address configuration: For IP communication, this link requires an IP address configuration, which indicates one of the following values:

[0226] - "DHCPv4 server", which acts as a DHCPv4 server if only the IPv4 address allocation mechanism is supported by the target UE; or

[0227] - "IPv6 Router", if the target UE only supports the IPv6 address allocation mechanism, then it acts as an IPv6 router; or

[0228] - "DHCPv4 server and IPv6 router", if both IPv4 and IPv6 address allocation mechanisms are supported by the target UE; or

[0229] - "Address allocation not supported" if neither the IPv4 nor IPv6 address allocation mechanism is supported by the target UE.

[0230] - Link-local IPv6 address: A link-local IPv6 address formed locally based on RFC 4862

[17] , provided that the target UE does not support the IPv6 IP address allocation mechanism, i.e., the IP address configuration indicates "address allocation not supported", and UE-1 includes the link-local IPv6 address in the direct communication request message. The target UE should include a non-conflicting link-local IPv6 address.

[0231] If two UEs (i.e., the initiating UE and the target UE) are selected to use link-local IPv6 addresses, then both UEs will disable dual address detection as defined in RFC 4862

[17] .

[0232] Note 3: When the initiating UE or the target UE indicates support for IPv6 routing, the corresponding address configuration procedure will be performed after the Layer 2 link is established, and the link-local IPv6 address will be ignored.

[0233] The ProSe layer of a UE establishing a PC5 unicast link will pass down the allocated PC5 link identifier and related PC5 unicast link information to the AS layer. The information associated with the PC5 unicast link includes Layer 2 ID information (i.e., source Layer 2 ID and destination Layer 2 ID). This allows the AS layer to maintain the PC5 link identifier and related PC5 unicast link information.

[0234] 6. Transmit ProSe data via the established unicast link as follows:

[0235] The PC5 link identifier and PFI, along with ProSe data, are provided to the AS layer.

[0236] Alternatively, the Layer 2 ID information (i.e., the source Layer 2 ID and the destination Layer 2 ID) may be provided to the AS layer.

[0237] Note 4: The UE implementation plan provides the Layer 2 ID information to the AS layer.

[0238] UE-1 sends ProSe data using the source layer 2 ID (i.e., the layer 2 ID of UE-1 used for this unicast link) and the destination layer 2 ID (i.e., the layer 2 ID of the peer UE used for this unicast link).

[0239] Note 5: PC5 unicast links are bidirectional, so UE-1's peer UE can send ProSe data to UE-1 through the unicast link with UE-1.

[0240] [...]

[0241] 6.4.3.3 Layer 2 Link Release via PC5 Reference Point

[0242] Figure 6 4.3.3-1 illustrates the Layer 2 link release procedure performed via the PC5 reference point.

[0243] The 3GPP TS 23.304 V17.0.0 is named "Layer 2 Link Release Procedure". Figure 6 4.3.3-1 was reproduced as Figure 10 ]

[0244] 0. UE-1 and UE-2 have unicast links established as described in Clause 6.4.3.1.

[0245] 1. UE-1 sends a disconnect request message to UE-2 to release the Layer 2 link and delete all context data associated with the Layer 2 link. The disconnect request message contains security information.

[0246] 2. Upon receiving the disconnect request message, UE-2 will respond with a disconnect response message and delete all context data associated with the Layer 2 link. The disconnect response message contains security information.

[0247] Each UE's ProSe layer notifies the AS layer that a unicast link has been released. The ProSe layer uses a PC5 link identifier to indicate the released unicast link. This allows the AS layer to remove the context associated with the released unicast link.

[0248] Note: Security information in the above messages is defined in TS 33.YYY [TBD].

[0249] [...]

[0250] 6.4.3.6 Layer 2 Link Management via PC5 Reference Point for 5G ProSe UE-to-Network Relay

[0251] The Layer 2 link procedure for unicast mode 5G ProSe direct communication via a PC5 reference point, as described in Clauses 6.4.3.1 to 6.4.3.5, may be used between the 5G ProSe remote UE and the PC5 reference point from the 5G ProSe UE to the network relay, with the following differences and clarifications:

[0252] - The Layer 2 link modification procedure applies to ProSe communication via 5G ProSe Layer 3 UE to network relay, while other procedures apply to ProSe communication via 5G ProSe Layer 2 UE to network relay and ProSe communication via 5G ProSe Layer 3 UE to network relay.

[0253] Editor's Note: Whether the Layer 2 link modification procedure also applies to ProSe communication from a 5G ProSe Layer 2 UE to a network relay requires cooperation with RAN2.

[0254] - UE-1, representing a 5G ProSe remote UE, and UE-2, representing a 5G ProSe UE-to-network relay, use UE-oriented Layer 2 link establishment. For other procedures, UE-1 represents a 5G ProSe remote UE and UE-2 represents a 5G ProSe UE-to-network relay, or UE-1 represents a 5G ProSe UE-to-network relay and UE-2 represents a 5G ProSe remote UE. That is, Layer 2 link establishment is initiated by the 5G ProSe remote UE, while other procedures can be initiated by either the 5G ProSe remote UE or the 5G ProSe UE-to-network relay.

[0255] For UE-oriented Layer 2 link establishment as described in Clause 6.4.3.1,

[0256] - In step 1, the 5G ProSe remote UE determines the destination layer 2 ID for PC5 unicast link establishment based on the unicast source layer 2 ID of the selected 5G ProSe UE to network relay during UE to network relay discovery as specified in clause 6.3.2.3 (as specified in clause 5.8.3).

[0257] - In step 2, the 5G ProSe remote UE (UE-1) determines the relay service code to be used. The relay service code to be used is selected from the received relay service codes during UE-to-network relay discovery as specified in Clause 6.3.2.3.

[0258] - In step 3, the 5G ProSe remote UE (UE-1) sends a unicast direct communication request message to the selected 5G ProSe UE-to-network relay. The destination Layer 2 ID used to send the direct communication request message should be the unicast Layer 2 ID determined in step 1. The direct communication request message includes:

[0259] - Source user information: The identity of the remote UE requesting the relay operation.

[0260] - Target user information: Provides the identity of the UE-to-network relay to the 5G ProSe remote UE during the UE-to-network relay discovery procedure.

[0261] - Relay service code: Indicates a connectivity service provided by a 5G ProSe UE to a network relay, as requested by a 5G ProSe remote UE.

[0262] - Security information: Information used to establish security.

[0263] - In steps 4 and 5, if the identity of the 5G ProSe UE to network relay matches the identity provided in the target user information and the relay service code is one of the relay service codes included during UE to network relay discovery as specified in Clause 6.3.2.3, then steps 4a and 5a are performed. The source user information in the direct communication accept message is the identity of the UE to network relay. In the case of 5G ProSe Layer 2 UE to network relay, the remote UE does not send the IP address configuration, link-local IPv6 address, and QoS information to the 5G ProSe Layer 2 UE to network relay, and the direct communication accept message does not contain the IP address configuration, link-local IPv6 address, and QoS information. In the case of 5G ProSe Layer 3 UE to network relay, the direct communication accept message does not contain the IP address configuration with the indication value "address allocation not supported".

[0264] - In the case of 5G ProSe Layer 2 UE to network relay, step 6 is not performed.

[0265] Regarding the release of Layer 2 links as described in Clause 6.4.3.3,

[0266] - In step 1, if the Layer 2 link release procedure is initiated by the 5G ProSe UE to network relay, then the disconnect request message may indicate that the 5G ProSe UE to network relay is temporarily unavailable, as described in Clause 5.12.

[0267] Note: The form of the instruction will be determined in Phase 3 if it is temporarily unavailable.

[0268] - If the service authorization for acting as a 5G ProSe remote UE or a 5G ProSe UE to network relay is revoked, then the 5G ProSe UE to network relay should initiate the release of the Layer 2 link affected by the revoked authorization.

[0269] For Layer 2 link modifications as described in Clause 6.4.3.4,

[0270] - In step 1, a 5G ProSe Layer 3 remote UE can initiate a Layer 2 link modification procedure based on application information received from its ProSe application layer. The link modification request message may contain PC5 QoS rules for the PC5 QoS flow to be added or modified, as described in Clause 5.6.2.1. A 5G ProSe Layer 3 UE to network relay can initiate a Layer 2 link modification procedure based on information received from the SMF via NAS signaling from the SMF.

[0271] If existing unicast links are established with different relay service codes or without relay service codes, then separate PC5 unicast links should be set up for 5G ProSe remote UEs and 5G ProSe UEs to network relays.

[0272] [...]

[0273] 6.5.2 5G ProSe Communication from UE to Network Relay via 5G ProSe Layer 2

[0274] 6.5.2.1 Registration and Connection Management

[0275] 6.5.2.1.1 Registration Management

[0276] Registration management for 5G ProSe Layer 2 remote UEs and 5G ProSe Layer 2 UE-to-network relays follows the principles and procedures defined in TS 23.501 [4] and TS 23.502 [5]. 5G ProSe Layer 2 remote UEs and 5G ProSe Layer 2 UE-to-network relays can be served by the same AMF or different AMFs.

[0277] 6.5.2.1.2 Connection Management

[0278] Connection management for 5G ProSe Layer 2 remote UEs and 5G ProSe Layer 2 UEs to network relays follows the principles and procedures defined in TS23.501 [4] and TS 23.502 [5] with the following modifications.

[0279] When a 5G ProSe Layer 2 UE-to-network relay is in the CM-CONNECTED state, it can relay only data / signaling for 5G ProSe Layer 2 remote UEs. If a 5G ProSe Layer 2 UE-to-network relay is in the CM_IDLE state and receives a connection request for relaying from a 5G ProSe Layer 2 remote UE, it should trigger a service request procedure to enter the CM_CONNECTED state before relaying the 5G ProSe Layer 2 remote UE service.

[0280] The status of the 5G ProSe UE to the network relay is controlled by NG-RAN as follows:

[0281] - If any 5G ProSe Layer 2 remote UE connected to the 5G ProSe Layer 2 UE to network relay is in CM-CONNECTED with RRC connection state, then the 5G ProSe Layer 2 UE to network relay should remain in CM-CONNECTED with RRC connection state.

[0282] - If all 5G ProSe Layer 2 remote UEs connected to the 5G ProSe Layer 2 UE to network relay enter CM-IDLE or CM-CONNECTED with RRC inactive state, then the 5G ProSe Layer 2 UE to network relay can enter CM-IDLE state or CM-CONNECTED with RRC inactive state.

[0283] When a 5G ProSe Layer 2 remote UE is in CM-CONNECTED state, the 5G ProSe Layer 2 UE maintains a PC5 link with the network relay. When a 5G ProSe Layer 2 remote UE is in CM-IDLE state, it may or may not release the PC5 link used for relaying.

[0284] In order to page a 5G ProSe Layer 2 remote UE, it follows the principles and procedures defined in TS 23.501 [4] and TS 23.502 [5], and the delivery of paging messages from NG-RAN to the 5G ProSe Layer 2 remote UE is specified in TS 38.351

[28] .

[0285] 6.5.2.2 Connection Establishment

[0286] The title of 3GPP TS 23.304 V17.0.0 is "Connection Establishment for 5G ProSe Layer 2 UE to Network Relay". Figure 6 .5.2.1-1 was reproduced as Figure 11 ]

[0287] 0. If within coverage area, the 5G ProSe Layer 2 remote UE and the 5G ProSe Layer 2 UE to network relay can independently perform the initial registration to the network according to the registration procedure in TS 23.502 [5].

[0288] 1. If within coverage area, the 5G ProSe Layer 2 remote UE and the 5G ProSe Layer 2 UE to network relay independently obtain service authorization for 5G ProSe Layer 2 UE to network relay operation from the network. Service authorization and parameter provisioning for 5G ProSe Layer 2 UE to network relay operation are performed for both the 5G ProSe Layer 2 UE to network relay and the 5G ProSe Layer 2 remote UE, as specified in Clause 5.1.4.

[0289] If the 5G ProSe Layer 2 remote UE is not in coverage, then pre-configured parameters are used, and service authorization and parameters can be updated after step 6.

[0290] If the 5G ProSe Layer 2 remote UE has not yet performed initial registration, then the 5G ProSe Layer 2 remote UE can perform initial registration in step 6.

[0291] 2. 5G ProSe Layer 2 remote UEs and 5G ProSe Layer 2 UE-to-network relays perform 5G ProSe UE-to-network relay discovery and selection as specified in Clause 6.3.2.3.

[0292] 3. The 5G ProSe Layer 2 remote UE initiates a one-to-one communication connection with the selected 5G ProSe Layer 2 UE to the network relay via PC5 using the procedure described in Clause 6.4.3.

[0293] 4. If the 5G ProSe Layer 2 UE to network relay is in the CM_IDLE state and is triggered by a request received from the 5G ProSe Layer 2 remote UE, then the 5G ProSe Layer 2 UE to network relay executes the service request procedure in Clause 4.2.3.2 of TS 23.502 [5].

[0294] Editor's Note: Triggering the ProSe UE to perform a service request procedure to the network relay requires collaboration with RAN2 and SA3 progress based on mutual authentication during PC5 connection establishment.

[0295] 5. A 5G ProSe Layer 2 remote UE establishes an RRC connection with the same NG-RAN serving the selected 5G ProSe Layer 2 UE to the network relay, as specified in TS 38.351

[28] .

[0296] 6. The 5G ProSe Layer 2 remote UE sends a NAS message to the serving AMF. The NAS message is encapsulated in a Uu RRC message sent via PC5 to the 5G ProSe Layer 2 UE to the network relay, and the 5G ProSe Layer 2 UE to the network relay forwards the Uu RRC message to the NG-RAN, as specified in TS 38.351

[28] . The NG-RAN selects the serving AMF of the 5G ProSe Layer 2 remote UE and forwards the NAS message to this AMF.

[0297] If the 5G ProSe Layer 2 remote UE has not yet performed initial registration, then the NAS message is an initial registration message. Otherwise, the NAS message is a service request message, or a mobility or periodic registration message.

[0298] 7. A 5G ProSe Layer 2 remote UE may trigger a PDU session establishment procedure, as defined in Clause 4.3.2.2 of TS 23.502 [5].

[0299] 8. Data is transmitted between the 5G ProSe Layer 2 remote UE and the UPF via the 5G ProSe Layer 2 UE to the network relay and NG-RAN. The 5G ProSe Layer 2 UE to the network relay forwards all data messages between the 5G ProSe Layer 2 remote UE and the NG-RAN as specified in TS 38.351

[28] .

[0300] 3GPP R2-2111437 introduces sidelink relay for NR Rel-17 in 3GPP TS 38.300. Remote UE paging reception via UE-to-network (U2N) relay is specified in 3GPP R2-2111437 as follows:

[0301] 16.x.5.4 Paging

[0302] When both the U2N trunk UE and the U2N remote UE are in RRC IDLE / RRC INACTIVE, the U2N trunk UE monitors the paging times of the U2N remote UE connected to its PC5-RRC. When the U2N trunk UE needs to monitor paging for the U2N remote UE, the U2N trunk UE should monitor all Paging Points (POs) for the U2N remote UE.

[0303] When a U2N relay UE is in RRC CONNECTED and a U2N remote UE is in RRC_IDLE or RRC_INACTIVE, there are two options for paging delivery:

[0304] - If the DL BWP in the U2N relay UE is configured with CORESET and common search space, then the U2N relay UE monitors the PO of the U2N remote UE it is connected to.

[0305] - Paging delivery for U2N remote UEs can be performed via a dedicated RRC message from the gNB to the U2N relay UE. The dedicated RRC message used to deliver paging for a remote UE to the RRC_CONNECTED relay UE may contain one or more remote UE IDs (5G-S-TMSI or I-RNTI).

[0306] The network implementation scheme determines which option to use. If a paging common search space is configured, a U2N trunk UE in RRC CONNECTED mode can determine whether to monitor POs for the U2N remote UE based on PC5-RRC signaling received from the U2N remote UE.

[0307] Editor's Note: Whether a U2N relay UE in RRC_IDLE / INACTIVE state can also determine the PO for monitoring a U2N remote UE based on PC5-RRC signaling received from a U2N remote UE requires further investigation.

[0308] The U2N remote UE in RRC_IDLE / RRC_INACTIVE state provides the 5G-S-TMSI / I-RNTI and its Uu DRX loop information to the U2N relay UE for PO monitoring. The L2 U2N relay UE can notify the gNB of the remote UE ID (i.e., 5G-S-TMSI / I-RNTI) information via a dedicated RRC message for paging delivery purposes. The U2N relay UE decodes the received paging message to derive the 5G-S-TMSI / I-RNTI and sends a paging message to the remote UE accordingly.

[0309] Editor's Note: The Uu DRX loop information described in the paragraph above is subject to further research. U2N relay UEs use unicast signaling to send paging messages to U2N remote UEs via PC5.

[0310] 3GPP R2-2111490 introduces sidelink relay for NR Rel-17 in 3GPP TS 38.331. Remote UE paging reception via UE-to-network (U2N) relay is specified in 3GPP R2-2111490 as follows:

[0311] 5.8.9.x2 Remote UE Information

[0312] 5.8.9.x2.1 General Principles

[0313] The name of 3GPP R2-2111490 is "Remote UE Information". Figure 5 .8.9.x2.1-1 was reproduced as Figure 12 ]

[0314] L2 U2N remote UEs in RRC_IDLE / RRC_INACTIVE use this procedure to inform the required SIB and provide paging-related information to the connected L2 U2N trunk UEs.

[0315] Editor's Note: If a later meeting concludes that two separate messages are needed for paging information and SIB requests, then an update will be required.

[0316] Actions related to the transmission of RemoteInformationSidelink messages in version 5.8.9.x2.2

[0317] L2 U2N remote UEs in RRC_IDLE or RRC_INACTIVE state should:

[0318] 1> If the UE has not yet stored a valid version of one or more required SIBs according to clause 5.2.2.2.1:

[0319] 2> Include sl-Requested-SI-List in RemoteUEInformationSidelink to indicate the requested SIB;

[0320] Editor's Note: Further research is needed on how to handle MIB and SIB1.

[0321] 1> Configure sl-RemotePagingIdentity as follows:

[0322] 2> If the L2 U2N remote UE is in RRC_IDLE:

[0323] 3> Include ng-5G-S-TMSI in sl-RemotePagingIdentity;

[0324] 3> Include a UE-specific DRX cycle in the sl-PagingCycle;

[0325] 2> Otherwise, if the L2 U2N remote UE is in RRC_INACTIVE:

[0326] 3> Include ng-5G-S-TMSI and fullI-RNTI in sl-RemotePagingIdentity;

[0327] 3> Include a UE-specific DRX cycle in the sl-PagingCycle;

[0328] 1> Submit the RemoteUEInformationSidelink message to the lower layer for transmission;

[0329] Uu message transmission in the side link of 5.8.9.x3

[0330] 5.8.9.x3.1 General Provisions

[0331] The 3GPP R2-2111490 specification is titled "Uu Message Transmission in Side Link". Figure 5 .8.9.x3.1-1 was reproduced as Figure 13 ]

[0332] The purpose of this procedure is to transmit paging messages and system information from an L2 U2N relay UE to an L2 U2N remote UE in RRC_IDLE / RRC_INACTIVE.

[0333] Editor's Note: If a later meeting concludes that two separate messages are needed for paging and SIB forwarding, then an update will be required.

[0334] Actions related to the transmission of UuMessageTransferSidelink messages in version 5.8.9.x3.2

[0335] Upon receiving paging messages and system information related to the connected L2 U2N remote UE from the network, the L2 U2N relay UE immediately initiates a Uu message transmission. The UE should configure the content of the UuMessageTransferSidelink message as follows:

[0336] 1> If the paging message received from the network contains the associated ue-Identity of the L2 U2N remote UE, then it contains sl-PagingDelivery;

[0337] 1> If a system information message received from the network is requested by an L2 U2N remote UE, then it includes sl-SystemInformationDelivery;

[0338] 1> Submit UuMessageTransferSidelink messages to the lower layer for transmission.

[0339] Receiving messages via UuMessageTransferSidelink (version 5.8.9.x3.3)

[0340] Upon receiving the UuMessageTransferSidelink message, the L2 U2N remote UE should:

[0341] 1> If sl-PagingDelivery is included, then:

[0342] 2> Perform the procedures as defined in Clause 5.3.2.3;

[0343] 1> If sl-SystemInformationDeliverySidelink is included, then:

[0344] 2> Perform the actions specified in Clause 5.2.2.4;

[0345] 3GPP TS 23.304 describes support for UE-to-network relay in a subsequent release (i.e., release 17), meaning that a relay UE will be used to support communication between the remote UE and the network when the remote UE cannot directly access the network. Two different types of solutions exist for UE-to-network (U2N) relay: Layer 2 U2N relay and Layer 3 U2N relay.

[0346] 3GPP TS 23.304 V17.0.0 Figure 6 Section 5.2.1-1 describes the connection establishment for 5G ProSe Layer 2 UE-to-network relay. When a remote UE is within coverage area, after initial registration and service authorization retrieval performed by the remote UE, if there is a request for connectivity services from an upper layer or upper layer application, the remote UE can perform UE-to-network relay discovery and selection. Both Model A discovery and Model B discovery are supported for remote UEs to discover U2N relays. Model A uses a single discovery protocol message (i.e., discovery notification), and Model B uses two discovery protocol messages (i.e., discovery request and discovery response). The Relay Service Code (RSC) is included in the 5G ProSe UE-to-network relay discovery to instruct the relay UE to provide or the remote UE to request connectivity services from the relay UE. The RSC is configured for the relay UE and the remote UE according to Section 5.1.4 of 3GPP TS 23.304. Relay UEs supporting multiple RSCs can announce the RSC using multiple discovery messages, one RSC per discovery message. A remote UE can monitor notification messages with an RSC corresponding to the desired connectivity service. When multiple relay UEs are present in the vicinity of the remote UE, one of the relay UEs can be selected based on, for example, the RSC contained in the discovery message and the measurement results on the discovery message transmitted by the relay UE.

[0347] After selecting a suitable relay UE, the remote UE can subsequently establish a PC5 unicast link with the relay UE to support U2N relay operation. The remote UE can include an RSC in the direct communication request message sent to the relay UE to establish the PC5 unicast link. After the PC5 unicast link is established, the remote UE can subsequently establish a Radio Resource Control (RRC) connection with the same NG-RAN (i.e., gNB) serving the selected relay UE and set up a NAS connection with the serving AMF. Finally, the remote UE can establish a Protocol Data Unit (PDU) session with the network (i.e., UPF) to obtain the required connectivity services provided by the data network. The relay UE can forward all service data between the remote UE and the NG-RAN. If the remote UE wants to access another connectivity service via the relay UE, it should establish another separate PC5 unicast link with the relay UE.

[0348] According to 3GPP R2-2111437, when a PC5 unicast link is established between a remote UE and a relay UE for accessing connectivity services via the relay UE, the remote UE can also receive paging messages from the relay UE. The remote UE can cyclically transmit its identity and UE-specific DRX to the relay UE, allowing the relay UE to monitor all paging opportunities (POs) for the remote UE or receive paging messages via dedicated RRC signaling from the NG-RAN, and then forward the paging messages to the remote UE, as described in 3GPP R2-2111437 and R2-2111490. Paging allows the network to reach remote UEs in RRC_IDLE and RRC_INACTIVE states via paging messages. In other words, paging messages are used to inform the remote UE of mobile termination services (e.g., call termination). Upon receiving a paging message, a remote UE in RRC_IDLE or RRC_INACTIVE can subsequently initiate an RRC procedure to establish or restore an RRC connection to access mobile termination services from the network.

[0349] Since the remote UE needs to discover the relay UE and establish a PC5 unicast link with the relay UE based on the RSC corresponding to the required connectivity service, this implies that the remote UE should initiate relay discovery when the upper layer (or upper layer application) requests the required connectivity service. In other words, the current U2N relay operation is triggered only when there is a mobile originating service request from the upper layer. Furthermore, the mobile termination service is available only when an active mobile originating service exists in the remote UE. However, it would be advantageous for the remote UE to connect to the relay UE solely for receiving paging messages via the relay UE, so that when no active mobile originating service exists in the remote UE, it can access the mobile termination service from the network (e.g., terminate the call).

[0350] In general, one possible solution is to define a specific RSC to support paging reception for remote UEs via U2N relays. Following a request for paging reception from an upper layer or upper layer application, the remote UE can discover the relay UE and establish a PC5 unicast link with the relay UE using the specific RSC. The specific RSC can be included in a relay discovery message transmitted by either the remote UE or the relay UE. The remote UE can also include the specific RSC in a direct communication request message transmitted to the relay UE for establishing the PC5 unicast link. After the PC5 unicast link is established, the remote UE can cyclically transmit its identity and the UE-specific DRX configured for the remote UE to the relay UE, enabling the relay UE to monitor / receive paging messages for the remote UE. If any paging messages for the remote UE are received from the network, the relay UE can subsequently forward the paging information or messages to the remote UE. The remote UE will not initiate any PDU session establishment with the network (e.g., UPF) in response to requests for paging reception from an upper layer or upper layer application. If a separate PC5 unicast link with the relay UE is established using a different RSC, the remote UE can release the PC5 unicast link used to support paging reception of remote UEs via U2N relays, as this PC5 unicast link is no longer needed. In one embodiment, the specific RSC can be a default value, a predefined value, or configured by the network for the remote UE.

[0351] Alternatively, any RSC configured for the remote UE can be used to support paging reception of the remote UE via U2N relay. In other words, the remote UE can use any RSC to discover the relay UE and establish a PC5 unicast link with the relay UE, while the remote UE will not establish a PDU session with the network corresponding to the RSC after the PC5 unicast link is established. After the PC5 unicast link is established, the remote UE can cyclically transmit the remote UE's identity and UE-specific discontinuous reception (DRX) configured for the remote UE to the relay UE, enabling the relay UE to monitor / receive paging messages for the remote UE. If any paging message for the remote UE is received from the network, the relay UE can then forward the paging information or message to the remote UE. If a separate PC5 unicast link with the relay UE is established using a different RSC, the remote UE can release the PC5 unicast link used to support paging reception of the remote UE via U2N relay, as this PC5 unicast link is no longer needed. In one embodiment, the RSC can be configured for the remote UE by the network.

[0352] Figure 14This is a flowchart 1400 of a method for receiving paging information from a UE to a network relay. In step 1405, the remote UE establishes a PC5 unicast link with the relay UE using RSC, where RSC is specifically used for receiving paging information from the UE to the network relay. In step 1410, the remote UE receives paging information for itself via the relay UE. In one embodiment, the remote UE can discover the relay UE with RSC.

[0353] In one embodiment, the RSC may be included in a direct communication request message sent to a relay UE for establishing a PC5 unicast link. The RSC may also be included in a UE-to-network relay discovery notification message sent by the relay UE or a UE-to-network relay discovery request message sent by a remote UE. The RSC may be a default value, a predefined value, or configured by the network.

[0354] In one embodiment, a remote UE can cyclically transmit its identity and UE-specific DRX to a relay UE. Due to a request for paging reception from an upper layer or upper layer application, the remote UE may not initiate any PDU session establishment towards the network. If other PC5 unicast links are established between the remote UE and the relay UE using different RSCs, the remote UE can initiate a procedure to release the PC5 unicast link. In one embodiment, the relay UE may be a Layer 2 UE-to-network relay. The PC5 unicast link may be a Layer 2 link. In one embodiment, the establishment of a PC5 unicast link may be initiated due to a request for paging reception from an upper layer or upper layer application.

[0355] Return to reference Figure 3 and 4 In one exemplary embodiment of the method for a remote UE, the remote UE 300 includes program code 312 stored in memory 310. CPU 308 can execute program code 312 to enable the remote UE to: (i) establish a PC5 unicast link with a relay UE using RSC, wherein the RSC is specifically used for paging reception via the UE to the network relay, and (ii) receive paging information for the remote UE via the relay UE. Furthermore, CPU 308 can execute program code 312 to perform all the foregoing actions and steps or other actions and steps described herein.

[0356] Figure 15This is a flowchart 1500 of a method for receiving paging information via a UE to a network relay. In step 1505, the remote UE establishes a PC5 unicast link with the relay UE using an RSC for paging reception via the relay UE, where the RSC is any RSC configured for the remote UE. In step 1510, the remote UE receives paging information for itself via the relay UE. In one embodiment, the establishment of the PC5 unicast link may be initiated due to a request for paging reception from an upper layer or an upper layer application.

[0357] In one embodiment, a remote UE can discover a relay UE with an RSC. The RSC can be included in a direct communication request message sent to the relay UE for establishing a PC5 unicast link. The RSC can also be included in a UE-to-network relay discovery notification message sent by the relay UE or a UE-to-network relay discovery request message sent by the remote UE.

[0358] In one embodiment, the RSC can instruct the relay UE to provide connectivity services to a remote UE. The remote UE can cyclically transmit its identity and UE-specific DRX to the relay UE.

[0359] In one embodiment, a remote UE may not initiate any PDU session establishment toward the network due to a request for paging reception from an upper layer or an upper layer application. If other PC5 unicast links are established between the remote UE and the relay UE using different RSCs, the remote UE may initiate a procedure to release the PC5 unicast link.

[0360] In one embodiment, the relay UE can be a Layer 2 UE-to-network relay. The PC5 unicast link can be a Layer 2 link.

[0361] Return to reference Figure 3 and 4 In one exemplary embodiment of the method for a remote UE, the remote UE 300 includes program code 312 stored in memory 310. CPU 308 can execute program code 312 to enable the remote UE to: (i) establish a PC5 unicast link with a relay UE using an RSC for paging reception via the relay UE, wherein the RSC is any RSC configured for the remote UE; and (ii) receive paging information for the remote UE via the relay UE. Furthermore, CPU 308 can execute program code 312 to perform all the foregoing actions and steps or other actions and steps described herein.

[0362] Generally, after power-on, the (remote) UE will first perform cell selection to choose a suitable cell for pre-occupancy. If no suitable cell is found or the cell's reception quality is low, the UE can then determine to find a relay UE so that the (remote) UE can pre-occupy the relay UE's serving cell via the relay UE, at least for receiving paging information from the remote UE via the relay UE. Therefore, alternatively, when the remote UE is enabled (and / or authorized) to use Layer 2 U2N relay / if the remote UE is enabled (and / or authorized) to use Layer 2 U2N relay / after the remote UE is enabled (and / or authorized) to use Layer 2 U2N relay, the remote UE supporting the use of Layer 2 U2N relay can first at least discover the Layer 2 relay UE. The remote UE can then select a Layer 2 relay UE and connect to the selected Layer 2 relay UE. The remote UE can establish a first Layer 2 link (or PC5 unicast link or PC5-S connection) with the selected Layer 2 relay UE. A remote UE can send a PC5-S message (e.g., a direct communication request message) to a Layer 2 relay UE to request the establishment of a Layer 2 link. The PC5-S message or the direct communication request message can be included in a first RSC discovered in a discovery message received from the Layer 2 relay UE.

[0363] A remote UE supporting Layer 2 U2N relays can begin discovering at least one Layer 2 relay UE and / or connecting to a selected Layer 2 relay UE before initiating the first connectivity service (for forwarding traffic between the remote UE and the network via any (Layer 2) relay UE). This allows the remote UE to receive paging information from the Layer 2 relay UE before initiating the first connectivity service. The remote UE can send a first PC5 RRC message (e.g., a RemoteInformationSidelink message) necessary for receiving paging information via the Layer 2 link to the relay UE. The first PC5 RRC message may contain the remote UE's identity (e.g., S-TMSI and / or I-RNTI) and a UE-specific DRX cycle. The relay UE can then subsequently send a second PC5 RRC message (e.g., a UuMessageTransferSidelink message) containing paging information for the remote UE via the Layer 2 link to the remote UE.

[0364] The remote UE may also support the use of Layer 3 U2N trunks. Once the Just-in-First Connectivity Service is initiated, the remote UE can perform trunk reselection to reselect a new trunk UE. For example, the Just-in-First Connectivity Service can be associated with a second RSC providing Layer 3 U2N trunk services. In this case, the remote UE can perform trunk discovery to discover at least a Layer 3 trunk UE. The remote UE can reselect a Layer 3 trunk UE from the discovered Layer 3 trunk UE and connect to the Layer 3 trunk UE by establishing a second Layer 2 link with the Layer 3 trunk UE. In this case, the remote UE can release the first Layer 2 link. Another possibility is that the remote UE can establish a second Layer 2 link with the Layer 3 trunk UE while still maintaining the first Layer 2 link established with the Layer 2 trunk UE. In this case, the remote UE can receive paging information for the remote UE from the Layer 2 trunk UE through the first Layer 2 link and transmit Just-in-First Connectivity Service services between the remote UE and the network via the Layer 3 trunk UE through the second Layer 2 link.

[0365] As another example, if the first connectivity service is also associated with the first RSC, the remote UE will still maintain the first Layer 2 link established with the Layer 2 relay UE. The remote UE can initiate a PDU session establishment procedure for the first connectivity service with the network via the Layer 2 relay UE (through the Layer 2 link).

[0366] It's also possible that the first connectivity service is associated with a third RSC providing Layer 2 U2N relay service, and the Layer 2 relay UE can also send another discovery message containing the third RSC. In this case, the remote UE can establish a third Layer 2 link with the Layer 2 relay UE. The establishment of the third Layer 2 link can be because the first RSC associated with the first Layer 2 link is different from the third RSC associated with the third Layer 2 link. In this case, the remote UE can initiate a PDU session establishment procedure for the exact first connectivity service with the network via the Layer 2 relay UE (through the third Layer 2 link). In this case, the remote UE can release the first Layer 2 link. Alternatively, instead of establishing a third Layer 2 link and releasing the first Layer 2 link, it's also possible that the remote UE can initiate a PDU session establishment procedure through the first Layer 2 link for the exact first connectivity service with the network via the Layer 2 relay UE, since both the first and third RSCs are associated with the Layer 2 U2N relay service.

[0367] Figure 16This is a flowchart 1600 of a method for receiving paging information from a UE to a network relay. In step 1605, the UE discovers one or more relay UEs before initiating the first connectivity service for relaying, wherein the one or more relay UEs broadcast discovery messages, each discovery message containing an RSC providing Layer 2 U2N relay service. In step 1610, the UE selects a first relay UE from the one or more relay UEs. In step 1615, the UE establishes a first Layer 2 link with the first relay UE. In step 1620, the UE receives paging information for the UE from the first relay UE via the first Layer 2 link.

[0368] Return to reference Figure 3 and 4 In one exemplary embodiment of the method for a UE, the UE 300 includes program code 312 stored in memory 310. CPU 308 can execute program code 312 to enable the UE to: (i) discover one or more relay UEs prior to the initiation of a first connectivity service for relaying, wherein the one or more relay UEs broadcast discovery messages, each discovery message containing an RSC providing Layer 2 U2N relay service; (ii) select a first relay UE from the one or more relay UEs; (iii) establish a first Layer 2 link with the first relay UE; and (iv) receive paging information for the UE from the first relay UE via the first Layer 2 link. Furthermore, CPU 308 can execute program code 312 to perform all the above actions and steps or other actions and steps described herein.

[0369] Figure 17 This is a flowchart 1700 of a method for receiving paging information from a UE to a network relay. In step 1705, the UE is enabled to use a Layer 2 type U2N relay. In step 1710, in response to the ability to use a Layer 2 type U2N relay, the UE discovers one or more relay UEs, wherein the one or more relay UEs broadcast discovery messages, each discovery message containing an RSC providing Layer 2 U2N relay service. In step 1715, the UE selects a first relay UE from the one or more relay UEs. In step 1720, the UE establishes a first Layer 2 link with the first relay UE. In step 1725, the UE receives paging information for the UE from the first relay UE via the first Layer 2 link.

[0370] Return to reference Figure 3 and 4In one exemplary embodiment of the method for a UE, the UE 300 includes program code 312 stored in memory 310. CPU 308 can execute program code 312 to enable the UE to: (i) be enabled to use a Layer 2 type U2N relay, (ii) discover one or more relay UEs in response to the ability to use a Layer 2 type U2N relay, wherein the one or more relay UEs broadcast discovery messages, each discovery message containing an RSC providing Layer 2 U2N relay service, (iii) select a first relay UE from the one or more relay UEs, (iv) establish a first Layer 2 link with the first relay UE, and (v) receive paging information for the UE from the first relay UE via the first Layer 2 link. Furthermore, CPU 308 can execute program code 312 to perform all the above actions and steps or other actions and steps described herein.

[0371] exist Figure 16 and 17 In the context of the embodiments illustrated and discussed above, in one embodiment, the UE may not initiate any connectivity services for relaying before it begins to discover the one or more relay UEs. A first Layer 2 link may be associated with a first RSC, and the first RSC may indicate a first relay UE providing Layer 2 U2N relay services.

[0372] In one embodiment, after establishing a Layer 2 link with the relay user equipment, the UE can initiate a connectivity service for relaying. The connectivity service can be associated with a second RSC, and the second RSC is associated with a Layer 3 U2N relay service.

[0373] In one embodiment, the UE can reselect a second relay UE, wherein the second relay UE sends a discovery message containing a second RSC. The UE can establish a second PC5 unicast link with the second relay UE. The UE can release the first PC5 unicast link with the first relay UE. Connectivity services can be associated with the first RSC.

[0374] In one embodiment, the UE can initiate a PDU session establishment procedure or establish a PDU session for connectivity services with the network node via a first relay UE. The UE can transmit connectivity services between the UE and the network node via a Layer 2 link through the first relay UE.

[0375] In one embodiment, the first relay UE may be a Layer 2 relay UE. The second relay UE may be a Layer 3 relay UE. The UE may be a remote UE. The network node may be a base station, an Access and Mobility Management Function (AMF), a Session Management Function (SMF), or a User Plane Function (UPF).

[0376] Figure 18This is a flowchart 1800 of a method for receiving paging information from a UE to a network relay. In step 1805, the remote UE uses an RSC to discover the relay UE and establish a PC5 unicast link with the relay UE before initiating any connectivity services. The RSC is specifically defined for receiving paging information from the UE to the network relay or is any RSC configured for connectivity services. In step 1810, the remote UE receives paging information from the remote UE via the relay UE.

[0377] In one embodiment, an RSC may be included in a UE-to-network relay discovery notification message transmitted by a relay UE or a UE-to-network relay discovery request message transmitted by a remote UE. An RSC may also be included in a direct communication request message transmitted to a relay UE for establishing a PC5 unicast link. An RSC specifically defined for paging reception via UE-to-network relay may be a default value, a predefined value, or configured by the network. Any RSC configured for connectivity services may indicate the connectivity services offered by the relay UE to a remote UE.

[0378] In one embodiment, a remote UE can cyclically transmit its identity and UE-specific DRX to a relay UE. If other PC5 unicast links are established between the remote UE and the relay UE using different RSCs, the remote UE can initiate a procedure to release the PC5 unicast link.

[0379] In one embodiment, the relay UE can be a Layer 2 UE-to-network relay. The PC5 unicast link can be a Layer 2 link.

[0380] Return to reference Figure 3 and 4 In one exemplary embodiment of the method for a remote UE, the remote UE 300 includes program code 312 stored in memory 310. CPU 308 can execute program code 312 to enable the remote UE to: (i) discover a relay UE and establish a PC5 unicast link with the relay UE using an RSC before initiating any connectivity service, wherein the RSC is specifically defined for paging reception via the UE to the network relay or any RSC configured for connectivity service; and (ii) receive paging information from the remote UE via the relay UE. Furthermore, CPU 308 can execute program code 312 to perform all the foregoing actions and steps or other actions and steps described herein.

[0381] According to 3GPP TS 38.304, when a UE is connected, the NAS layer should select a Public Land Mobile Network (PLMN). The UE can then initiate a registration procedure with the network if necessary. After the registration procedure is completed, if a mobile termination service is initiated for the UE, the network can reach the UE via paging. According to 3GPP TS 23.304, an L2 remote UE needs to discover one or more L2 relay UEs to find an authorized / available PLMN, and then select one of the authorized / available PLMNs in the NAS PLMN selection. Therefore, an L2 remote UE can initiate relay discovery for PLMN selection after its connection is established.

[0382] According to 3GPP TS 23.304, a remote UE needs to discover a relay UE and establish a PC5 unicast link with the relay UE based on the RSC corresponding to the required connectivity service. Therefore, this implies that the remote UE should initiate relay discovery when the upper layer (or upper layer application) requests the required connectivity service. In other words, the current U2N relay operation is triggered only when there is a mobile originating service request from the upper layer. However, an out-of-coverage (OOC) L2 remote UE may need to perform a registration procedure with the network to receive paging after its connection is established. In this case, the L2 remote UE needs to discover and connect to a suitable relay UE for registration with the network via that relay UE. In other words, the L2 remote UE may need to connect to a suitable relay UE before the upper layer (or upper layer application) requests the required connectivity service.

[0383] In general, one possible solution is to define a specific RSC for relay UE discovery due to the need for remote UE to be connected (or powered on) or register. The remote UE can use the specific RSC to discover the relay UE (and establish a PC5 unicast link with the relay UE). The specific RSC can be included in the relay discovery message transmitted by the remote UE or the relay UE. The remote UE can also include the specific RSC in the direct communication request message transmitted to the relay UE to establish the PC5 unicast link. After the PC5 unicast link is established, the remote UE can initiate a registration procedure with the network via the relay UE through the PC5 unicast link. After the PC5 unicast link is established, the remote UE can cyclically transmit its identity and the UE-specific DRX configured for the remote UE to the relay UE, enabling the relay UE to monitor / receive paging messages for the remote UE. If any paging message for the remote UE is received from the network, the relay UE can then forward the paging information or message to the remote UE. Preferably, the specific RSC can be a default value, a predefined value, or configured by the network for the remote UE.

[0384] Alternatively, a remote UE can use any RSC that provides Layer 2 U2N relay service to discover one or more L2 U2N relay UEs when the remote UE is activated. The RSC can be provisioned or (pre)configured to the UE. The remote UE can then select a Layer 2 relay UE and connect to the selected Layer 2 relay UE. The remote UE can establish a first Layer 2 link (or PC5 unicast link or PC5-S connection) with the selected Layer 2 relay UE. The remote UE can send a PC5-S message (e.g., a direct communication request message) to the Layer 2 relay UE to request the establishment of the first Layer 2 link. The PC5-S message or direct communication request message can include the first RSC discovered in a discovery message received from the selected Layer 2 relay UE.

[0385] A remote UE supporting Layer 2 U2N relays can begin discovering at least one Layer 2 relay UE and / or connecting to a selected Layer 2 relay UE before initiating the first connectivity service (for forwarding traffic between the remote UE and the network via any (Layer 2) relay UE). This makes it possible for the remote UE to receive paging information for the remote UE from the Layer 2 relay UE before initiating the first connectivity service. The remote UE can send a first PC5 RRC message (e.g., a RemoteInformationSidelink message) necessary for receiving paging information for the remote UE via a Layer 2 link to the relay UE. The first PC5 RRC message may contain the remote UE's identity (e.g., S-TMSI and / or I-RNTI) and a UE-specific DRX cycle. The relay UE can then send a second PC5 RRC message (e.g., a UuMessageTransferSidelink message) containing paging information for the remote UE to the remote UE via the Layer 2 link.

[0386] If the first connectivity service is initiated (and associated with the first RSC or another RSC that also provides L2 U2N relay service), then the remote UE can initiate a PDU session establishment procedure for the first connectivity service via the Layer 2 relay UE to the network (through the Layer 2 link).

[0387] Figure 19 This is a flowchart 1900 of a method for receiving paging information from a UE to a network relay. In step 1905, the remote UE is activated. In step 1910, the remote UE performs a first relay UE discovery using a first RSC, wherein the first RSC is specifically used for relay UE discovery due to the UE activation, or the first RSC is provided or (pre)configured to the remote UE and is associated with connectivity services. In step 1915, the remote UE selects a relay UE based on a discovery message received from the relay UE, wherein the discovery message contains the first RSC.

[0388] In one embodiment, the remote UE can establish a PC5 unicast link or PC5 RRC connection with the relay UE using a first RSC. After the PC5 unicast link or PC5 RRC connection is established, the remote UE can receive paging information for itself via the relay UE.

[0389] In one embodiment, the first RSC may be included in a direct communication request message transmitted to the relay UE for establishing a PC5 unicast link. The first RSC may also be included in a UE-to-network relay discovery notification message transmitted by the relay UE during the first relay UE discovery period, or a UE-to-network relay discovery request message transmitted by a remote UE. The first RSC may be a default value, a predefined value, or configured by the network.

[0390] In one embodiment, a remote UE can cyclically transmit its identity and UE-specific DRX to a relay UE. The relay UE can be a Layer 2 UE-to-network relay. The PC5 unicast link can be a Layer 2 link.

[0391] In one embodiment, the remote UE may initiate a registration procedure with the first network node via the relay UE after a PC5 unicast link or PC5 RRC connection is established. Prior to the remote UE performing the first relay UE discovery using the first RSC, there may be no connectivity service requests from the upper layer or upper layer applications in the remote UE.

[0392] In one embodiment, an upper layer or upper layer application in a remote UE may request connectivity services. The remote UE may perform second relay UE discovery using a second RSC associated with connectivity services. The remote UE may initiate a PDU session establishment procedure or establish a PDU session for connectivity services with a second network node via a second relay UE discovered during second relay UE discovery.

[0393] In one embodiment, the first network node may be an AMF. The second network node may be an SMF or a UPF. Each of the RSCs supplied or (pre-)configured to a remote UE can provide Layer 2 UE-to-network relay communication.

[0394] Return to reference Figure 3 and 4In one exemplary embodiment of the method for a remote UE, the remote UE 300 includes program code 312 stored in memory 310. CPU 308 can execute program code 312 to enable the remote UE to: (i) turn on the remote UE, (ii) perform a first relay UE discovery using a first RSC, wherein the first RSC is specifically used for relay UE discovery due to the UE being turned on, or the first RSC is provided or (pre)configured for the remote UE and any of the RSCs associated with connectivity services, and (iii) select a relay UE based on a discovery message received from the relay UE, wherein the discovery message contains the first RSC. Furthermore, CPU 308 can execute program code 312 to perform all of the above actions and steps or other actions and steps described herein.

[0395] Figure 20 This is a flowchart 2000 of a method for receiving paging information from a network relay via a UE. In step 2005, the UE is enabled to use a Layer 2 type U2N relay. In step 2010, the UE discovers one or more relay UEs in response to the ability to use a Layer 2 type U2N relay. In step 2015, the UE selects a relay UE from the one or more relay UEs. In step 2020, the UE establishes a Layer 2 link with the relay UE. In step 2025, the UE receives paging information from the relay UE via the Layer 2 link.

[0396] In one embodiment, the one or more relay UEs broadcast multiple discovery messages, each of which may contain an RSC that provides Layer 2 U2N relay services. The UE has not initiated any connectivity services for relaying before it begins discovering the one or more relay UEs. Layer 2 links may be associated with RSCs, and the RSCs indicate the relay UE providing Layer 2 U2N relay services.

[0397] In one embodiment, after establishing a Layer 2 link with the relay user equipment, the UE can initiate connectivity services for relaying. The UE can initiate a PDU session establishment procedure or establish a PDU session for connectivity services with the network node via the relay UE. The UE can transmit connectivity service traffic between the UE and the network node via the Layer 2 link through the relay UE.

[0398] In one embodiment, a network node may be a base station, an access and mobility management function (AMF), a session management function (SMF), or a user plane function (UPF).

[0399] Return to reference Figure 3 and 4In one exemplary embodiment of the method for a UE, the UE 300 includes program code 312 stored in memory 310. CPU 308 can execute program code 312 to enable the UE to: (i) be enabled to use a Layer 2 type U2N relay, (ii) discover one or more relay UEs in response to the ability to use a Layer 2 type U2N relay, (iii) select a relay UE from the one or more relay UEs, (iv) establish a Layer 2 link with the relay UE, and (v) receive paging information from the relay UE via the Layer 2 link. Furthermore, CPU 308 can execute program code 312 to perform all the foregoing actions and steps or other actions and steps described herein.

[0400] Various aspects of this disclosure have been described above. It should be understood that the teachings herein can be implemented in a wide variety of forms, and any specific structure, function, or both disclosed herein are merely representative. Based on the teachings herein, those skilled in the art will understand that the aspects disclosed herein can be implemented independently of any other aspects, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement an apparatus or practice. Furthermore, such apparatuses or practices can be implemented using structures, functions, or structures and functions other than or different from those set forth herein. As examples of some of the foregoing concepts, in some aspects, a parallel channel can be established based on the pulse repetition frequency. In some aspects, a parallel channel can be established based on the pulse position or offset. In some aspects, a parallel channel can be established based on a jump sequence. In some aspects, a parallel channel can be established based on the pulse repetition frequency, the pulse position or offset, and a time jump sequence.

[0401] Those skilled in the art will understand that information and signals can be represented using any of a variety of different techniques and skills. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description can be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, light fields or light particles, or any combination thereof.

[0402] Those skilled in the art will further appreciate that the various illustrative logic blocks, modules, processors, components, circuits, and algorithmic steps described in conjunction with the aspects disclosed herein can be implemented as electronic hardware (e.g., a digital implementation designed using source decoding or some other technique, an analog implementation, or a combination of both), incorporating various forms of program or design code with instructions (which, for convenience, may be referred to herein as "software" or "software module"), or a combination of both. To clearly illustrate the interchangeability of hardware and software, the various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether this functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the system as a whole. Those skilled in the art can implement the described functionality in different ways for each specific application, but such implementation decisions should not be construed as a departure from the scope of this disclosure.

[0403] Furthermore, the various illustrative logic blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented within or executed by an integrated circuit (“IC”), access terminal, or access point. An IC may include a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, electrical components, optical components, mechanical components, or any combination thereof designed to perform the functions described herein, and may execute code or instructions residing within the IC, outside the IC, or both. A general-purpose processor may be a microprocessor, but alternatively, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration.

[0404] It should be understood that any particular order or hierarchy of steps in any disclosed process is an instance of an example method. It should be understood that the specific order or hierarchy of steps in a process can be rearranged based on design preferences, while remaining within the scope of this disclosure. The appended method claims give the elements of each step in an exemplary order and are not intended to limit one to the given specific order or hierarchy.

[0405] The steps of the methods or algorithms described in conjunction with the aspects disclosed herein can be implemented directly in hardware, with software modules executed by a processor, or a combination of both. Software modules (e.g., containing executable instructions and associated data) and other data can reside in data memory, such as RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM, or any other form of computer-readable storage medium known in the art. Example storage media can be coupled to a machine such as a computer / processor (for convenience, the machine may be referred to herein as a "processor"), such that the processor can read information (e.g., code) from the storage medium and write information to the storage medium. Example storage media can be integrated with a processor. The processor and storage medium can reside in an ASIC. The ASIC can reside in a user equipment. Alternatively, the processor and storage medium can reside as discrete components in a user equipment. Furthermore, in some aspects, any suitable computer program product may include a computer-readable medium comprising code associated with one or more aspects of this disclosure. In some aspects, the computer program product may include packaging material.

[0406] While the invention has been described in conjunction with various aspects, it should be understood that further modifications are possible. This application is intended to cover any changes, uses, or adaptations to the invention that generally follow the principles of the invention and include such deviations from this disclosure that fall within the scope of known and customary practice in the art to which this invention pertains.

Claims

1. A method for receiving paging messages via a user equipment to a network relay, characterized in that, include: User equipment is authorized to use Layer 2 type user equipment to relay to the network to support mobile termination service; After being authorized to use a Layer 2 type user equipment to relay to the network to support the mobile termination service, the user equipment discovers one or more relay user equipments, wherein the user equipment has not initiated any connectivity services for relaying before the user equipment begins to discover the one or more relay user equipments. The user equipment selects a relay user equipment from the one or more relay user equipments; The user equipment establishes a Layer 2 link with the relay user equipment; as well as The user equipment receives paging information from the relay user equipment via the layer 2 link.

2. The method according to claim 1, characterized in that, The one or more relay user equipments broadcast discovery messages, each discovery message containing a relay service code that provides Layer 2 user equipment to network relay services.

3. The method according to claim 1, characterized in that, The Layer 2 link is associated with a relay service code, and the relay service code instructs the relay user equipment to provide Layer 2 user equipment to network relay service.

4. The method according to claim 1, characterized in that, Also includes: After establishing a Layer 2 link with the relay user equipment, the user equipment initiates a connectivity service for relaying.

5. The method according to claim 4, characterized in that, Also includes: The user equipment initiates a Protocol Data Unit (PDU) session establishment procedure or establishes a PDU session for the connectivity service via the relay user equipment to the network node.

6. The method according to claim 5, characterized in that, Also includes: The user equipment transmits the connectivity service between the user equipment and the network node via the layer 2 link through the relay user equipment.

7. The method according to claim 5, characterized in that, The network node is a base station, access and mobility management function, session management function, or user plane function.

8. A user equipment for receiving paging messages via a network relay from a user equipment, characterized in that, include: Control circuit; A processor, which is installed in the control circuit; as well as A memory, which is mounted in the control circuit and operatively coupled to the processor; The processor is configured to execute program code stored in the memory to: Authorized to use Layer 2 type user equipment to relay to the network to support mobile termination service; After being authorized to use a Layer 2 type user equipment to relay to the network to support the mobile termination service, one or more relay user equipments are discovered, wherein the user equipment has not initiated any connectivity services for relaying before the user equipment begins to discover the one or more relay user equipments; Select a trunk user equipment from the one or more trunk user equipments; Establish a Layer 2 link with the relay user equipment; as well as The paging information is received from the relay user equipment via the layer 2 link.

9. The user equipment according to claim 8, characterized in that, The one or more relay user equipments broadcast discovery messages, each discovery message containing a relay service code that provides Layer 2 user equipment to network relay services.

10. The user equipment according to claim 8, characterized in that, The Layer 2 link is associated with a relay service code, and the relay service code instructs the relay user equipment to provide Layer 2 user equipment to network relay service.

11. The user equipment according to claim 8, characterized in that, The processor is also configured to execute program code stored in the memory to perform the following operations: After establishing a Layer 2 link with the relay user equipment, a connectivity service for relaying is initiated.

12. The user equipment according to claim 11, characterized in that, The processor is also configured to execute program code stored in the memory to perform the following operations: The relay user equipment initiates a Protocol Data Unit (PDU) session establishment procedure to the network node or establishes a PDU session for the connectivity service.

13. The user equipment according to claim 12, characterized in that, Also includes: The user equipment transmits the connectivity service between the user equipment and the network node via the layer 2 link through the relay user equipment.

14. The user equipment according to claim 12, characterized in that, The network node is a base station, access and mobility management function, session management function, or user plane function.

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