Abstract: A method and apparatus are disclosed. In an example from the perspective of a User Equipment (UE), the UE receives and/or detects a multicast transmission of downlink data on a configured downlink multicast resource, wherein the multicast transmission is associated with a Hybrid Automatic Repeat Request (HARQ) process. The UE starts a multicast HARQ Round Trip Time (RTT) timer associated with the HARQ process. The UE determines whether to start a unicast HARQ RTT timer associated with the HARQ process based on whether the UE is configured with a Configured Scheduling Radio Network Temporary Identifier (CS-RNTI).

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 apparatus are disclosed. In an example from the perspective of a User Equipment (UE), the UE receives one or more signals indicative of a first Physical Uplink Shared Channel (PUSCH) and a second PUSCH on a first cell and in a Transmission Time Interval (TTI). The UE determines to transmit a first Uplink Control Information (UCI) in the TTI, wherein the first UCI overlaps with the first PUSCH and the second PUSCH in time domain. The UE selects the first PUSCH for multiplexing the first UCI based on whether the UE is configured with joint Hybrid Automatic Repeat Request (HARQ) feedback mode or separate HARQ feedback mode. The UE transmits the first PUSCH and the second PUSCH on the first cell, wherein the first PUSCH transmitted on the first cell includes the first UCI.

Abstract: Methods, systems, and apparatuses can comprise a User Equipment (UE) receiving a system information including at least a first Non-terrestrial Network (NTN) configuration for a serving cell, starting or restarting a validity timer for the serving cell in response to receiving the system information, receiving a Radio Resource Control (RRC) reconfiguration message with ReconfigurationWithSync for a target cell, stopping, in response to receiving the RRC reconfiguration message, the validity timer that is running based on the first NTN configuration, and starting the validity timer based on a second NTN configuration for the target cell.

Abstract: Methods, systems, and apparatuses can comprise receiving a Sidelink (SL) grant, wherein the SL grant indicates a SL transmission, starting or restarting a first timer for a SL Hybrid Automatic Repeat Request (HARQ) process in a first symbol after the end of a Physical Uplink Control Channel (PUCCH) resource associated with the SL grant, or the SL transmission, when the first device does not transmit a SL HARQ feedback for the SL HARQ process on the PUCCH resource due to measurement gap or Listen-Before-Talk (LBT) failure, starting or restarting a second timer for the SL HARQ process in a first symbol, after the first timer expires, when the first device does not transmit the SL HARQ feedback for the SL HARQ process on the PUCCH resource due to measurement gap, or LBT failure, and the SL HARQ feedback is a negative acknowledgement, and monitoring a Physical Downlink Control Channel (PDCCH) when the second timer is running.

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.