Abstract: In an example, a User Equipment (UE) operates with shared spectrum channel access on a carrier and/or a cell. The UE receives a configuration for configuring configured grants for uplink transmission in a bandwidth part (BWP). The configured grants include a first configured grant and a second configured grant. The UE configures a first minimum Downlink Feedback Indication (DFI) time delay for the first configured grant according to the configuration. The first minimum DFI time delay is for validation of Hybrid Automatic Repeat Request (HARQ) information in response to one or more first uplink transmissions. The UE configures a second minimum DFI time delay for the second configured grant according to the configuration. The second minimum DFI time delay is for validation of HARQ information in response to one or more second uplink transmissions. The UE does not expect the second minimum DFI time delay to have a different value than the first minimum DFI time delay.

Abstract: A method and apparatus are disclosed from the perspective of a UE, wherein the UE is allocated with multiple SR configurations by a network node. In one embodiment, the method includes the UE triggering a MAC control element if a timer expires. The method also includes the UE triggering a SR for the MAC control element. The method also includes the UE transmitting the SR based on a first SR configuration of the multiple SR configurations, wherein the first SR configuration is associated with a highest priority logical channel having data available for transmission when the MAC control element is triggered.

Abstract: A method and apparatus are disclosed from the perspective of a communication device. In one embodiment, the method includes the device being configured with a plurality of resource pools by a base station for a cell. The method further includes the device receiving a grant from the base station, wherein the grant indicates a resource associated with a resource pool of the plurality of resource pools through a resource pool index in the grant. The method also includes the device using the resource to perform a transmission on a device-to-device interface.

Abstract: A method and apparatus are disclosed from the perspective of a UE, wherein the UE is allocated with multiple SR configurations by a network node. In one embodiment, the method includes the UE triggering a MAC control element if a timer expires. The method also includes the UE triggering a SR for the MAC control element. The method also includes the UE transmitting the SR based on a first SR configuration of the multiple SR configurations, wherein the first SR configuration is associated with a highest priority logical channel having data available for transmission when the MAC control element is triggered.

Abstract: A method and apparatus are disclosed from the perspective of a device to perform sidelink communication. In one embodiment, the method includes the device receiving a sidelink grant from a network node, wherein the sidelink grant schedules or assigns multiple sidelink resources. The method further includes the device generating a data packet comprising or multiplexing sidelink data from Sidelink (SL) logical channel(s) with SL Hybrid Automatic Request (HARD) feedback enabled. The method further includes the device performing two sidelink transmissions for the data packet on two adjacent, neighbor, or consecutive sidelink resources among the multiple sidelink resources if a time gap of the two adjacent, neighbor, or consecutive sidelink resources is larger than or equal to a minimum time gap.

Abstract: A method and apparatus are disclosed. In an example from the perspective of a first device, the first device performs sidelink communication with one or more destinations. The first device receives and/or selects a sidelink grant associated with a sidelink transmission. Responsive to the sidelink grant, the first device selects a first destination of the one or more destinations based upon a report signaling. The first device performs the sidelink transmission associated with the sidelink grant to the first destination.

Abstract: A method and device are disclosed from the perspective of a first device handling radio link failure. In one method, the method includes the first device performing or establishing sidelink unicast communication with a second device. The method also includes the first device performing or establishing sidelink unicast communication with a third device. The method also includes the first device detecting a radio link failure associated with the second device. The method further includes the first device performing a Sidelink MAC reset associated with the second device in response to the radio link failure, and not performing a Sidelink MAC reset associated with the third device.

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 apparatus are disclosed. In an example from the perspective of a User Equipment (UE), if sidelink packet duplication is configured or enabled for a Sidelink Radio Bearer (SLRB), a first Packet Data Convergence Protocol (PDCP) Protocol Data Unit (PDU), corresponding to a first PDCP Service Data Unit (SDU), and a duplicate of the first PDCP PDU, are transmitted. A first PDCP Sequence Number (SN) of the first PDCP PDU is set based upon one or more state variables used for sidelink transmission on the SLRB. If the sidelink packet duplication is de-configured or disabled for the SLRB, a second PDCP PDU, corresponding to a second PDCP SDU, is transmitted. Noduplicate of the second PDCP PDU is transmitted. A second PDCP SN of the second PDCP PDU is set based upon the one or more state variables used for sidelink transmission on the SLRB.

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 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 from the perspective of a first device. In one embodiment, the method includes the first device being configured with a Sidelink (SL) Discontinuous Reception (DRX) configuration. The method also includes the first device performing a sidelink communication with a second device. The method further includes the first device receiving a signaling, from the second device, indicating a new sidelink transmission. In addition, the method includes the first device determining whether to start or restart a timer in response to the signaling at least based on information indicated in the signaling, wherein the first device monitors sidelink control channel when the timer is running.

Abstract: A method and apparatus are disclosed for latency reduction of device-to-device message in a wireless communication system. In one embodiment, the method includes the UE receiving a grant on a first interface wherein the grant indicates resource for transmitting scheduling information and resources for data transmission on a second interface.

Abstract: A method and apparatus are disclosed from the perspective of a first device to determine sidelink feedback resource associated with sidelink communication. In one embodiment, the method includes the first device receiving an identifier from an upper layer of the first device. The method also includes the first device receiving a sidelink transmission from a second device. The method further includes the first device determining a sidelink feedback resource associated with the sidelink transmission at least based on the identifier and a source ID (Identity) associated with the sidelink transmission. In addition, the method includes the first device using the sidelink feedback resource to transmit a feedback in response to the sidelink transmission to the second device.

Abstract: A method and device are disclosed from the perspective of a first device handling radio link failure. In one method, the method includes the first device performing or establishing sidelink unicast communication with a second device. The method also includes the first device performing or establishing sidelink unicast communication with a third device. The method also includes the first device detecting a radio link failure associated with the second device. The method further includes the first device performing a Sidelink MAC reset associated with the second device in response to the radio link failure, and not performing a Sidelink MAC reset associated with the third device.

Abstract: A method and apparatus are disclosed. In an example from the perspective of a first device, the first device performs sidelink communication with one or more destinations. The first device receives and/or selects a sidelink grant associated with a sidelink transmission. Responsive to the sidelink grant, the first device selects a first destination of the one or more destinations based upon a report signaling. The first device performs the sidelink transmission associated with the sidelink grant to the first destination.

Abstract: A method and apparatus are disclosed from the perspective of a first device. In one embodiment, the method includes the first device receiving a configuration, from a network node, of a first sidelink resource pool without any Physical Sidelink Feedback Channel (PSFCH) resource. The method further includes the first device receiving a first sidelink grant transmitted, configured, or scheduled by the network node, wherein the first sidelink grant schedules or indicates at least a first sidelink resource in the first sidelink resource pool. Furthermore, the method includes the first device expecting or considering that the first sidelink grant provides no Physical Uplink Control Channel (PUCCH) resource for reporting Sidelink (SL) Hybrid Automatic Repeat Request (HARD) feedback.

Abstract: A method and apparatus are disclosed from the perspective of a User Equipment (UE). In one embodiment, the method includes the UE performing a first device-to-device (D2D) transmission based on a periodic resource. The method further includes the UE performs a second D2D transmission based on the periodic resource in response to no data available for the second D2D transmission, wherein the second D2D transmission indicates release of the periodic resource. The method also includes the UE stops using the periodic resource to perform a third D2D transmission.

Abstract: A method and apparatus are disclosed from the perspective of a device to perform sidelink transmission. The method includes the device being in RRC (Radio Resource Control)-connected mode in Uu link. The method also includes the device being configured to use at least DL (Downlink) pathloss for sidelink power control. The method further includes the device deriving a first DL pathloss value for determining an uplink transmit power of one specific kind of uplink transmission. In addition, the method includes the device determining or deriving a sidelink transmit power based on the first DL pathloss value. Furthermore, the method includes the device performing a sidelink transmission to other device(s) with the sidelink transmit power.

Abstract: A method and apparatus are disclosed. In an example from the perspective of a User Equipment (UE), if sidelink packet duplication is configured or enabled for a Sidelink Radio Bearer (SLRB), a first Packet Data Convergence Protocol (PDCP) Protocol Data Unit (PDU), corresponding to a first PDCP Service Data Unit (SDU), and a duplicate of the first PDCP PDU, are transmitted. A first PDCP Sequence Number (SN) of the first PDCP PDU is set based upon one or more state variables used for sidelink transmission on the SLRB. If the sidelink packet duplication is de-configured or disabled for the SLRB, a second PDCP PDU, corresponding to a second PDCP SDU, is transmitted. Noduplicate of the second PDCP PDU is transmitted. A second PDCP SN of the second PDCP PDU is set based upon the one or more state variables used for sidelink transmission on the SLRB.