Abstract: A method and apparatus are disclosed from the perspective of a UE (User Equipment) to handle a sidelink buffer status report (SL BSR). In one embodiment, the method includes the UE transmitting a SL BSR to a network node, wherein a format of the SL BSR includes at least one field of buffer size associated with HARQ (Hybrid Automatic Repeat Request) feedback enabled and one field of buffer size associated with HARQ feedback disabled. The method also includes the UE receiving a sidelink grant from the network node. The method further includes the UE selecting data from a logical channel for transmission according to a HARQ feedback mode of the logical channel and whether the sidelink grant is associated with a HARQ feedback resource or not.

Abstract: Methods and apparatuses for transmission or reception using beamforming in a wireless communication system are disclosed herein. In one method, a user equipment receives a second signal indicating a first information. The UE derives at least one specific UE beam based on the first information. The UE uses the at least one specific UE beam to receive or transmit at least one transmission, in which the at least one transmission is periodic channel state indication, scheduling request, and/or scheduling information for downlink assignment or uplink resource.

Abstract: A method and device are disclosed for PC5 Signaling (PC5-S) message reception from the perspective of a UE-to-UE relay. The UE-to-UE relay receives a first PC5-S message on a first sidelink Signal Radio Bearer (SRB) from a first UE, wherein the first PC5-S message is used to establish a first sidelink security between the UE-to-UE relay and the first UE, to update link identifier(s) associated with a first link between the first UE and the UE-to-UE relay, or to modify the first link between the first UE and the UE-to-UE relay. The UE-to-UE relay also delivers the first PC5-S message to an upper layer of the UE-to-UE relay.

Abstract: A method and device are disclosed for PC5 Signaling (PC5-S) message transmission from the perspective of a first User Equipment (UE). In one embodiment, the first UE communicates with a second UE via a UE-to-UE relay. The first UE also transmits a first PC5-S message on a first sidelink Signaling Radio Bearer (SRB) to the UE-to-UE Relay, wherein the first PC5-S message is used to establish a first sidelink security between the first UE and the UE-to-UE relay, to update link identifier(s) associated with a first link between the first UE and the UE-to-UE relay, or to modify the first link between the first UE and the UE-to-UE relay.

Abstract: A method and apparatus are disclosed. A first sidelink Signaling Radio Bearer (SRB) for PC5-S message transmission is established. The first sidelink SRB is associated with a default Destination Layer-2 Identity (ID). A first PC5-S message is transmitted on the first sidelink SRB with a Source Layer-2 ID derived from a Layer-2 ID of the first UE and a Destination Layer-2 ID derived from the default Destination Layer-2 ID. A second PC5-S message is received from a second UE. The second PC5-S message is transmitted with a Source Layer-2 ID derived from a Layer-2 ID of the second UE and a Destination Layer-2 ID derived from the Layer-2 ID of the first UE. A second sidelink SRB for PC5-S message reception and/or transmission is established. The second sidelink SRB is associated with the Layer-2 ID of the second UE.

Abstract: A method and device are disclosed from the perspective of a relay UE. In one embodiment, the relay UE establishes a Radio Resource Control (RRC) connection with a network node. The relay UE also transmits a Layer 2. Identity (L2ID) of the relay UE to the network node. Furthermore, the relay UE receives a local UE Identity (ID) for a remote UE and a L2ID of the remote UE from the network node. In addition, the relay UE establishes a PC5 connection with the remote UE. The relay UE further receives a first RRC Reconfiguration Complete message from the remote UE. The relay UE also transmits the first RRC Reconfiguration Complete message to the network node, wherein the first RRC Reconfiguration Complete message is included in an adaptation layer Protocol Data Unit (PDU) for transmission and the local UE ID for the remote UE is included in a header of the adaptation layer PDU.

Abstract: A method and apparatus are disclosed from the perspective of a first UE (User Equipment) to indicate a network node for releasing SLRB (Sidelink Radio Bearer) or SL-DRB (Sidelink-Data Radio Bearer). In one embodiment, the method includes transmitting a first RRC (Radio Resource Control) message to a network node for requesting sidelink resource, wherein the first RRC message includes a PFI (PC5 QoS Flow Identifier) of a PC5 QoS (Quality of Service) flow in a first list of PC5 QoS flows. The method also includes receiving a second RRC message from the network node, wherein the second RRC message configures a SLRB and maps the PC5 QoS flow to the SLRB. The method further includes transmitting a third RRC message to the network node if the PC5 QoS flow is deactivated or released, wherein the PFI of the PC5 QoS flow is removed from a second list of PC5 QoS flows included in the third RRC message.

Abstract: Methods and apparatuses for transmission or reception using beamforming in a wireless communication system are disclosed herein. In one method, a user equipment provides information related to a combination of UE beams to a network node, wherein UE beams in the combination can be generated by the UE at the same time. The UE receives, from the network node, a scheduling information for a transmission or a reception. The UE generates one or more UE beams in the combination to perform the transmission or the reception.

Abstract: A method and device are disclosed for radio bearer configuration to support User Equipment-to-Network (UE-to-Network) relaying from the perspective of a relay UE. In one embodiment, the relay UE establishes a PC5-Radio Resource Control (PC5-RRC) connection with a remote UE. The relay UE also transmits a RRC message to a network node to request a radio bearer configuration to support UE-to-Network relaying. Furthermore, the relay UE receives a RRC Reconfiguration message from the network node, wherein the RRC Reconfiguration message includes a Uu configuration for a Uu Radio Link Control (RLC) bearer associated with a signalling radio bearer (SRB). In addition, the relay UE receives a RRC Reconfiguration Complete message from the remote UE. The relay UE also transmits the RRC Reconfiguration Complete message on the Uu RLC bearer to the network node.

Abstract: A method and apparatus for beam detection in a wireless communication system. In one embodiment, the method includes the UE initiating a RA procedure. The method also includes the UE transmitting multiple RA preambles to a base station of the cell at different occasions for the base station to determine a beam set of the UE. The method further includes the UE starts monitoring a PDCCH for RA response reception from the base station after finishing transmissions of the multiple RA preambles.

Abstract: A method and apparatus are disclosed from the perspective of a first UE (User Equipment) to support multiple services on a one-to-one sidelink communication link between the first UE and a second UE. In one embodiment, the first UE initiates a first service. The first UE also establishes the one-to-one sidelink communication link for the first service. Furthermore, the first UE negotiates a security configuration with the second UE for encrypting or decrypting data from the first service. In addition, the first UE initiates a second service. The first UE also encrypts or decrypts data from the second service with the security configuration used by the first service.

Abstract: A method and apparatus are disclosed from the perspective of a User Equipment (UE), wherein the UE is configured with multiple Bandwidth Parts (BWPs). In one embodiment, the method includes the UE receiving information from a network node to associate a RACH (Random Access Channel) configuration with a BWP among the multiple BWPs. The method further includes that the UE performing a RACH transmission in the BWP using the RACH configuration associated with the BWP.

Abstract: A method and apparatus are disclosed from the perspective of a network node. In one embodiment, the method includes the network node transmitting a first message with a DRB (Data Radio Bearer) configuration to a UE (User Equipment) for establishing a default DRB for a PDU (Packet Data Unit) session, wherein the DRB configuration includes a QFI (QoS Flow Id) configuration used to indicate whether a QFI field is present or not in uplink for the default DRB and the QFI configuration is always set to a value indicating the QFI field is present in uplink for the default DRB. The method further includes the network node establishing the default DRB with a presence of the QFI field in uplink. The method also includes the network node receiving a SDAP (Service Data Adaptation Protocol) PDU with the QFI field via the default DRB from the UE.

Abstract: A method and apparatus for implementing reference signal transmissions in a wireless communication system. In one embodiment, the method includes the cell, transmission point (TP), or transmission and reception point (TRP) broadcasting a first RS periodically for measurement, wherein the first RS is transmitted at multiple occasions (or timings) in each period on different beams. The method also includes the cell, TP, or TRP transmitting a second RS to a UE for PDCCH demodulation, wherein the second RS is transmitted on multiple beams in a beam set of the UE in a subframe (or symbol) in which the PDCCH is transmitted.

Abstract: A method and apparatus are disclosed from the perspective of an initiating UE (User Equipment) for establishing a one-to-one sidelink communication with a target UE. In one embodiment, the method includes transmitting a first PC5 signaling used for establishing the one-to-one sidelink communication, wherein the first PC5 signaling includes an identity of the target UE and an identity of a V2X (Vehicle-to-Everything) service.

Abstract: Methods and apparatuses for transmission or reception using beamforming in a wireless communication system are disclosed herein. In one method, a user equipment provides information related to a combination of UE beams to a network node, wherein UE beams in the combination can be generated by the UE at the same time. The UE receives, from the network node, a scheduling information for a transmission or a reception. The UE generates one or more UE beams in the combination to perform the transmission or the reception.

Abstract: A method and apparatus are disclosed from the perspective of an initiating UE (User Equipment) for establishing a one-to-one sidelink communication with a target UE. In one embodiment, the method includes transmitting a first PC5 signalling used for establishing the one-to-one sidelink communication, wherein the first PC5 signalling includes an identity of the target UE and an identity of a V2X (Vehicle-to-Everything) service.

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.

Abstract: A method and device are disclosed for Uu radio bearer to Sidelink (SL) Radio Link Control (RLC) mapping. In one embodiment, the method includes a network node transmitting a Radio Resource Control (RRC) message to a relay User Equipment (UE), wherein the RRC message includes a first information indicating a mapping which represents an association between a Uu radio bearer and a SL RLC bearer and wherein the RRC message also includes a second information identifying a remote UE associated with the mapping. The method further includes the network node transmitting an adaptation layer Protocol Data Unit (PDU) to the relay UE, wherein a header of the adaptation layer PDU includes an identity of the Uu radio bearer and a local UE identifier of the remote UE.

Abstract: 23A wireless communications device has a first security key, a second security key, and established channels. Each established channel has a corresponding security count value, and utilizes a security key. At least one of the established channels utilizes the first security key. The second security key is assigned to a new channel. A first set is then used to obtain a first value. The first set has only security count values of all the established channels that utilize the second key. The first value is at least as great as the x most significant bits (MSBx) of the greatest value in the first set. The MSBx of the initial security count value for the new channel is set equal to the first value. If the first set is empty, then the initial security count is set to zero.