Abstract: A method and device for a first User Equipment (UE) are disclosed. In one embodiment, the first UE initiates a procedure for establishing a PC5 connection with a second UE. Furthermore, the first UE sends a first PC5 message to the second UE for request of establishment of the PC5 connection in the procedure, wherein the first PC5 message includes a first Sidelink (SL) positioning or ranging related information.

Abstract: A method and device are disclosed from the perspective of a second User Equipment (UE) to configure Sidelink (SL) Discontinuous Reception (DRX). In one embodiment, the method includes the second UE initiating or initializing a sidelink service with a first UE. The method also includes the second UE determining a SL DRX configuration based on association between sidelink service and SL DRX configuration, wherein the SL DRX configuration is associated with the sidelink service. The method further includes the second UE monitoring sidelink control channel based on the SL DRX configuration.

Abstract: A method and device are disclosed from the perspective of a remote User Equipment (UE). In one embodiment, the method includes the remote UE establishing a layer-2 link with a relay UE. The method further includes the remote UE establishing a Radio Resource Control (RRC) connection with a network via the relay UE. The method also includes the remote UE initiating or performing a RRC connection re-establishment procedure, wherein the remote UE determines to keep the layer-2 link with the relay UE in the RRC connection re-establishment procedure. In addition, the method includes the remote UE starting a timer T301 in response to keeping the layer-2 link with the relay UE.

Abstract: A method and device are disclosed for a User Equipment (UE) to sidelink discontinuous reception (DRX) for sidelink groupcast communication associated with a group. In one embodiment, the method includes the UE assuming or considering a sidelink DRX configuration applied for the sidelink groupcast communication associated with the group, wherein the sidelink DRX configuration comprises at least one of an on-duration timer length used for determining an on-duration at the beginning of each sidelink DRX cycle and/or a cycle length used for determining a length of each sidelink DRX cycle. The method also includes the UE deriving or determining a time to start of on-duration for each sidelink DRX cycle or start of each sidelink DRX cycle based on at least an identifier associated with the group.

Abstract: A method and device are disclosed for a first network node. In one embodiment, the method includes the first network node receiving a first information of candidate relay User Equipments (UEs) from a remote UE. The method further includes the first network node sending the first information of candidate relay UEs or a second information of candidate relay UEs to a second network node for the second network node to select a target relay UE, wherein the second information of candidate relay UEs is derived from the first information of candidate relay UEs.

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 apparatus are disclosed from the perspective of a UE (User Equipment). In one embodiment, the method includes the UE receiving a first signaling containing mapping between resource allocation mode(s) and attribute(s) of sidelink data of the UE from a base station. The method further includes the UE performing a sidelink transmission of the sidelink data based on the mapping between the resource allocation mode(s) and the attribute(s) of the sidelink data.

Abstract: A method and device are disclosed for supporting a third User Equipment (UE). In one embodiment, the third UE receives a first PC5-S message from a first UE for initiating a procedure of establishing a first layer-2 link between the first UE and the third UE. The third UE also transmits a second PC5-S message to the first UE for establishing a first security context between the first UE and the third UE in the procedure of establishing the first layer-2 link. The third UE further receives a third PC5-S message from the first UE for completing establishment of the first security context in the procedure of establishing the first layer-2 link. In addition, the third UE transmits a fourth PC5-S message to the first UE for completing the procedure of establishing the first layer-2 link, wherein the fourth PC5-S message includes a layer-2 identity of a second UE.

Abstract: A method and apparatus are disclosed from the perspective of a network node. In one embodiment, the method includes the network node configuring a UE (User Equipment) with a first DRB (Data Radio Bearer), wherein the first DRB is configured with a presence of SDAP (Service Data Adaptation Control) header and the network node is not allowed to reconfigure the first DRB with an absence of SDAP header before the first DRB is released. The method further includes the network node configuring the UE to serve a first QoS (Quality of Service) flow and a second QoS flow by the first DRB. The method also includes re-configuring the UE to serve the first QoS flow by a second DRB, which was originally served by the first DRB, if the second QoS flow is released or removed from the first DRB, wherein the second DRB is configured with an absence of SDAP header.

Abstract: A method and apparatus are disclosed from the perspective of a transmitting device. In one embodiment, the method includes being configured or allocated with an identity, wherein the identity comprises a first part of the identity and a second part of the identity. The method also includes the transmitting device generating a data packet for sidelink transmission, wherein the data packet includes the second part of the identity. Furthermore, the method includes transmitting device generating a control information associated with the data packet, wherein the control information includes the first part of the identity. The method further includes the transmitting device transmits the control information and the data packet.

Abstract: A method and apparatus are disclosed from the perspective of a first device to perform sidelink communication. In one embodiment, the method includes the first device performing sidelink resource selection or reselection procedure for a sidelink transmission to a second device, wherein the sidelink resource selection or reselection procedure is performed to select at least one sidelink resource from candidate sidelink resources within a time duration of selection window. The method further includes the first device selecting a first sidelink resource based on sidelink active time or wake-up time of the second device, wherein the first sidelink resource is within the time duration of selection window. The method also includes the first device performing the sidelink transmission on the first sidelink resource to the second device.

Abstract: A method and apparatus are disclosed from the perspective of a first device. In one embodiment, the method includes the first device performs sensing on a data resource pool, and the first device selects/derives at least a first data resource from the data resource pool based on the sensing result of the data resource pool. The method further includes the first device transmits a first control information on a first control resource, wherein the first control information allocates or indicates the first data resource. The method also includes the first device performs a first data transmission on the first data resource to at least one second device.

Abstract: A method and device are disclosed from the perspective of a first User Equipment (UE) to support Sidelink (SL) Discontinuous Reception (DRX). In one embodiment, the method includes the first UE establishing a unicast link with a second UE. The method further includes the first UE receiving a SL DRX configuration associated with the second UE from the second UE. The method also includes the first UE transmitting the SL DRX configuration to a network node. In addition, the method includes the first UE receiving a sidelink grant from the network node, wherein the sidelink grant indicates sidelink resources. Furthermore, the method includes the first UE performing a sidelink transmission to the second UE based on the sidelink resources.

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 from the perspective of a remote User Equipment (UE). In one embodiment, the method includes the remote UE establishing a unicast link with a relay UE. The method further includes the remote UE establishing a Radio Resource Control (RRC) connection with a network via the relay UE, wherein a first Radio Link Control (RLC) entity is created and used for transmitting a first RRC message for request of establishing the RRC connection to the network via the relay UE. The method also includes the remote UE selecting a suitable cell. In addition, the method includes the remote UE releasing the first RLC entity in response to selection of the suitable cell. Furthermore, the method includes the remote UE transmitting a second RRC message to the network directly.

Abstract: A method and apparatus are disclosed from the perspective of a first device to perform sidelink communication. In one embodiment, the method includes the first device performing sidelink resource selection or reselection procedure for a sidelink transmission to a second device, wherein the sidelink resource selection or reselection procedure is performed to select at least one sidelink resource from candidate sidelink resources within a time duration of selection window. The method further includes the first device selecting a first sidelink resource based on sidelink active time or wake-up time of the second device, wherein the first sidelink resource is within the time duration of selection window. The method also includes the first device performing the sidelink transmission on the first sidelink resource to the second device.

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 apparatus are disclosed from the perspective of a first device. In one embodiment, the method includes the first device performs sensing on a data resource pool, and the first device selects/derives at least a first data resource from the data resource pool based on the sensing result of the data resource pool. The method further includes the first device transmits a first control information on a first control resource, wherein the first control information allocates or indicates the first data resource. The method also includes the first device performs a first data transmission on the first data resource to at least one second device.