Method and apparatus for transmitting device-to-device sidelink report in a wireless communication system

A method of a first device to perform sidelink transmission, comprising:

• the first device includes a Medium Access Control (MAC) Control Element (CE) in a MAC Protocol Data Unit (PDU), wherein when the MAC PDU comprises the MAC CE without data, Sidelink (SL) Hybrid Automatic Repeat Request (HARQ) feedback is disabled for the MAC PDU;
• the first device includes (sidelink) data associated with a first sidelink logical channel in the MAC PDU, wherein the first sidelink logical channel is configured to enable sidelink HARQ feedback;
• the first device sets or indicates enable SL HARQ feedback for the MAC PDU in a SCI, wherein the SCI schedules a sidelink transmission delivering the MAC PDU;
• and
• the first device transmits the SCI and performs the sidelink transmission to a second device.

A first device, comprising:

• a control circuit;
• a processor installed in the control circuit;
• and
• a memory installed in the control circuit and operatively coupled to the processor;
• wherein the processor is configured to execute a program code stored in the memory to:
• receive a second unicast sidelink transmission from a second device, wherein the second unicast sidelink transmission indicates or triggers the first device to transmit a Sidelink (SL) Channel State Information (CSI) report;
• generate a Medium Access Control (MAC) Protocol Data Unit (PDU) without data, where the MAC PDU comprises a Control Element (MAC CE) for the SL CSI-report and set or indicate disable SL Hybrid Automatic Repeat Request (HARQ) feedback in a SCI when the first device does not have data associated with one or more sidelink logical channels available for transmitting to the second device;
• generate a MAC PDU for the data and includes the MAC CE for the SL CSI-report in the MAC PDU and set or indicate enable SL HARQ feedback in a SCI when the first device has data associated with one or more sidelink logical channels available for transmitting to the second device and the data is associated with the one or more sidelink logical channels configured with enabling SL HARQ feedback;
• transmit the SCI to the second device, wherein the SCI schedules a first unicast sidelink transmission delivering the MAC PDU;
• and
• receive or monitor SL HARQ feedback from the second device in response to the first unicast sidelink transmission in case the first device sets or indicates enable SL HARQ feedback in the SCI.

A first device, comprising:

• a control circuit;
• a processor installed in the control circuit;
• and
• a memory installed in the control circuit and operatively coupled to the processor;
• wherein the processor is configured to execute a program code stored in the memory to:
• include a Medium Access Control (MAC) Control Element (CE) in a MAC Protocol Data Unit (PDU), wherein when the MAC PDU comprises the MAC CE without data, Sidelink (SL) Hybrid Automatic Repeat Request (HARQ) feedback is disabled for the MAC PDU;
• include sidelink data associated with a first sidelink logical channel in the MAC PDU, wherein the first sidelink logical channel is configured to enable sidelink HARQ feedback;
• set or indicate enable SL HARQ feedback for the MAC PDU in a SCI, wherein the SCI schedules a sidelink transmission delivering the MAC PDU;
• and
• transmit the SCI and perform the sidelink transmission to a second device.