Abstract: A method and device for supporting multi-path (MP) transmission are disclosed. In one embodiment, a remote User Equipment (UE) communicates with a network node via a direct path and an indirect path. The remote UE also connects with a relay UE via sidelink (SL) or PC5 interface to support the indirect path. In addition, the remote UE is configured with direct bearers and indirect bearers by the network node. Furthermore, the remote UE transmits a buffer status report (BSR) and a SL-BSR to the network node over the direct path, wherein the BSR includes data volume of at least one of the direct bearers and the SL-BSR includes data volume of at least one of the indirect bearers.

Abstract: A method and device for supporting multi-path (MP) transmission are disclosed. In one embodiment, a relay User Equipment (UE) connects with a network node. The relay UE also connect with a remote UE via a non-3GPP standard interface. Furthermore, the relay UE is configured with a Radio Link Control (RLC) entity associated with an indirect bearer of the remote UE by the network node. In addition, the relay UE transmits a buffer status report (BSR) to the network node, wherein the BSR includes data volume in a Packet Data Convergence Protocol (PDCP) entity and the RLC entity and wherein the PDCP entity is associated with the indirect bearer and is established in the remote UE.

Abstract: A method and device for supporting multi-path transmission or communication. In one embodiment, a User Equipment (UE) establishes a Radio Resource Control (RRC) connection with a network node. The UE also transmits a RRC message to the network node, wherein the RRC message includes a Cell Radio Network Temporary Identifier (C-RNTI) of a relay UE. Furthermore, the UE receives a RRC Reconfiguration message from the network node, wherein the RRC Reconfiguration message includes a configuration of a Data Radio Bearer (DRB) and wherein the DRB is mapped to a first Radio Link Control (RLC) entity in the UE and a second RLC entity in the relay UE. In addition, the UE transmits a data packet of the DRB to the network node via the first RLC entity and/or the second RLC entity.

Abstract: A method and device for Quality of Service (QOS) flow establishment are disclosed. A relay User Equipment (UE) establishes a PC5 unicast link with a remote UE. The relay UE also receives an identity of a PC5 QoS flow and a first PC5 5G QoS Identifier (PQI) of the PC5 QoS flow from the remote UE for adding the PC5 QoS flow, wherein the first PQI indicates end-to-end QoS requirements of the PC5 QoS flow for traffic transmission between the remote UE and a network. The relay UE further derives a second PQI for the PC5 QoS flow and a 5QI for a QoS flow according to the first PQI. In addition, the relay UE transmits a Protocol Data Unit (PDU) Session Modification Request message to the network for adding the QoS flow, wherein the PDU Session Modification Request message includes an identity of the QoS flow and the 5QI.

Abstract: A method and device for duplicate PDU discarding. In one embodiment, a User Equipment (UE) establishes a direct path and an indirect path to communicate with a network. The UE also establishes a radio bearer, wherein the radio bearer is mapped to a first Radio Link Control (RLC) entity and a second RLC entity and wherein the first RLC entity is used for communication with the network over the direct path and the second RLC entity is used for communication with the network over the indirect path. In addition, a Packet Data Convergence Protocol (PDCP) entity, which is in the UE and which is associated with the radio bearer, prevents from indicating to the first RLC entity to discard a first PDCP PDU when successful delivery of the first PDCP PDU is confirmed by the second RLC entity.

Abstract: A method and device for Quality of Service (QOS) flow establishment are disclosed. A relay User Equipment (UE) establishes a PC5 unicast link with a remote UE. The relay UE also receives an identity of a PC5 QoS flow and a first PC5 5G QoS Identifier (PQI) of the PC5 QoS flow from the remote UE for adding the PC5 QoS flow, wherein the first PQI indicates end-to-end QoS requirements of the PC5 QoS flow for traffic transmission between the remote UE and a network. The relay UE further derives a second PQI for the PC5 QoS flow and a 5QI for a QoS flow according to the first PQI. In addition, the relay UE transmits a Protocol Data Unit (PDU) Session Modification Request message to the network for adding the QoS flow, wherein the PDU Session Modification Request message includes an identity of the QoS flow and the 5QI.

Abstract: A method and device are disclosed from the perspective of a first remote User Equipment (UE). In one embodiment, the method includes the first remote UE establishing a first Sidelink (SL) Data Radio Bearer (DRB) for transmission to a second remote UE via a relay UE, wherein the first SL DRB is identified by a Radio Bearer (RB) Identity (ID). The method further includes the first remote UE ciphering a sidelink packet to be sent to the second remote UE on the first SL DRB based on at least the RB ID.

Abstract: A method and apparatus are disclosed from the perspective of a first UE (User Equipment) to update Layer-2 Identities (IDs). In one embodiment, the method includes the first UE establishing a unicast link with a second UE, wherein a first Layer-2 ID of the first UE and a second Layer-2 ID of the second UE are used for data transmission and reception on the unicast link. The method further includes the first UE transmitting a Link Identifier Update Request message for the unicast link to the second UE, wherein the Link Identifier Update Request message includes a new first Layer-2 ID of the first UE. The method also includes the first UE receiving a Link Identifier Update Accept message for the unicast link from the second UE, wherein the Link Identifier Update Accept message includes a new second Layer-2 ID of the second UE.

Abstract: A method and device are disclosed for paging reception via UE-to-Network Relay. In one embodiment, the method includes a UE being enabled to use layer-2 type UE-to-Network (U2N) Relay. The method also includes the UE discovering one or more relay UEs in response to enabling of using layer-2 type U2N Relay. Furthermore, the method includes the UE selecting a relay UE from the one or more relay UEs. In addition, 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 over the layer-2 link.

Abstract: A method and device are disclosed from the perspective of a relay UE for Radio Resource Control (RRC) connection establishment to support User Equipment (UE)-to-Network relaying. In one embodiment, the method includes a relay UE establishing a PC5 RRC connection or a PC5 unicast link with a remote UE. The method also includes the relay UE receiving a RRC message from the remote UE. Furthermore, the method includes the relay UE initiating a RRC connection establishment with a network node in response to reception of the RRC message. In addition, the method includes the relay UE transmitting a Disconnect Request message to the remote UE to release the PC5 RRC connection or the PC5 unicast link or transmits a PC5 RRC message to the remote UE to inform the remote UE of a failure of the RRC connection establishment, if the RRC connection establishment fails.

Abstract: A method and device are disclosed from the perspective of a User Equipment-to-User Equipment (UE-to-UE) Relay to perform a link identifier update procedure. In one embodiment, the method includes the UE-to-UE Relay receiving a first PC5-S message from a first UE to modify at least one first link identifier, wherein the first PC5-S message includes a Layer-2 Identity (ID) of the first UE. The method also includes the UE-to-UE Relay transmitting a second PC5-S message to a second UE, in response to reception of the first PC5-S message, to modify at least one second link identifier, wherein the second PC5-S message includes a Layer-2 ID of the UE-to-UE Relay and does not include the Layer-2 ID of the first UE.

Abstract: A method and device are disclosed for supporting a communication path switching from PC5 to Uu. In one embodiment, the method includes a second User Equipment (UE) communicating with a first UE via a PC5 unicast link established between the first UE and the second UE. The method also includes the second UE receiving a path switch request message from the first UE, wherein the path switch request message indicates a path switching to Uu. The method further includes the second UE determining to accept the path switch request message according to at least a Uu signal level. In addition, the method includes the second UE transmitting a path switch accept message to the first UE.

Abstract: A method and device are disclosed from the perspective of a User Equipment-to-User Equipment (UE-to-UE) Relay to perform a PC5 unicast link establishment procedure. In one embodiment, the method includes the UE-to-UE Relay receiving a first PC5-S message from a first User Equipment (UE), wherein the first PC5-S message includes a Layer-2 Identity (ID) of a second UE. The method further includes the UE-to-UE Relay transmitting a second PC5-S message addressed to the Layer-2 ID of the second UE for establishing a PC5 unicast link with the second UE. The method also includes the UE-to-UE Relay receiving a third PC5-S message from the second UE, wherein the third PC5-S message is transmitted by the second UE in response to reception of the second PC5-S message.

Abstract: A method and apparatus are disclosed from the perspective of a first UE (User Equipment) to report UE sidelink capability information to a network node. In one embodiment, the method includes the first UE establishing a unicast link with a second UE. The method also includes the first UE receiving a second sidelink capability information of the second UE from the second UE. The method further includes the first UE transmitting a first sidelink capability information of the first UE and the second sidelink capability information to the network node or transmitting a common sidelink capability information to the network node, wherein the common sidelink capability information is derived from the first sidelink capability information and the second sidelink capability information.

Abstract: A method and device are disclosed for supporting UE-to-UE relay. In one embodiment, the method includes a relay User Equipment (UE) establishing a first layer-2 link with a first UE and establishes a second layer-2 link with a second UE, wherein the first layer-2 link and the second layer-2 link are used for forwarding traffic between the first UE and the second UE. The method also includes the relay UE receiving a first PC5 message from a third UE for request of establishing a third layer-2 link, wherein the first PC5 message includes a second User Info of the second UE. The method further includes the relay UE transmitting a second PC5 message to the second UE for modifying the second layer-2 link in response to reception of the first PC5 message from the third UE, wherein the second PC5 message includes a third User Info of the third UE and the second User Info of the second UE.

Abstract: A method and device are disclosed for connecting with another User Equipment (UE). In one embodiment, the method includes a first UE connecting with a second UE via a relay UE, wherein a first PC5 unicast link is established between the first UE and the relay UE. The method also includes the first UE transmitting a Link Modification Request message to the relay UE, wherein the Link Modification Request message includes a third User Info of a third UE. The method further includes the first UE receiving a Link Modification Accept message from the relay UE.

Abstract: A method and device are disclosed for a relay User Equipment (UE) supporting connection with another UE. In one embodiment, the method includes a relay UE establishing a first PC5 unicast link with the first UE and establishing a second PC5 unicast link with a second UE. The method also includes the relay UE forwarding data from the first UE to the second UE. The method further includes the relay UE receiving a Link Modification Request message from the first UE, wherein the Link Modification Request message includes a third User Info of a third UE. In addition, the method includes the relay UE transmitting a Direct Communication Request message to the third UE, wherein the Direct Communication Request message includes the third User Info of the third UE. Furthermore, the method includes the relay UE receiving a Direct Communication Accept message from the third UE.

Abstract: A method and apparatus are disclosed from the perspective of a first UE (User Equipment) to update Layer-2 Identities (IDs). In one embodiment, the method includes the first UE establishing a unicast link with a second UE, wherein a first Layer-2 ID of the first UE and a second Layer-2 ID of the second UE are used for data transmission and reception on the unicast link. The method further includes the first UE transmitting a Link Identifier Update Request message for the unicast link to the second UE, wherein the Link Identifier Update Request message includes a new first Layer-2 ID of the first UE. The method also includes the first UE receiving a Link Identifier Update Accept message for the unicast link from the second UE, wherein the Link Identifier Update Accept message includes a new second Layer-2 ID of the second UE.

Abstract: A method and apparatus are disclosed from the perspective of a UE (User Equipment). In one embodiment, the method includes the UE being configured with a control resource set (CORESET). The method further includes the UE receiving a Downlink Control Information (DCI) on the CORESET, wherein an index is included in the DCI and the index indicates a time domain resource allocation pattern. The method also includes the UE receiving data in Orthogonal Frequency Division Multiplexing (OFDM) symbols determined according to the time domain resource allocation pattern, wherein a range of the time domain resource allocation pattern starts from the first OFDM symbol of the CORESET or after an offset from the first OFDM symbol of the CORESET, and the range of the time domain resource allocation pattern may end across a slot boundary.

Abstract: A method and device are disclosed for a remote User Equipment (UE) to support UE-to-Network relay communication. The remote UE establishes a PC5 connection with a first relay UE for a relay communication with a first network node. The remote UE also performs a Radio Resource Control (RRC) connection establishment procedure with the first network node via the first relay UE. Furthermore, the remote UE transmits a first RRC message to a second network node via a second relay UE for requesting RRC connection re-establishment, wherein the first RRC message includes a first Cell Radio Network Temporary Identifier (C-RNTI) of the remote UE. Also, the remote UE receives a second RRC message from the second network node via the second relay UE for re-establishing a RRC connection between the second network node and the remote UE, wherein the second RRC message includes a second C-RNTI of the remote UE.