Method and apparatus for header compression configuration for sidelink radio bearer in a wireless communication system

A UE (User Equipment), 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:
• transmit a request to a network node for a SLRB configuration for establishing the SLRB used for V2X sidelink communication with other UE(s);
• receive the SLRB configuration from the network node, wherein the SLRB configuration includes a Packet Data Convergence Protocol (PDCP) configuration for the SLRB and wherein the PDCP configuration includes at least one PDCP parameter for the SLRB and includes no parameter used for determining whether header compression and decompression is used for transmitting V2X messages on the SLRB;
• and
• determine whether the header compression and decompression is used for transmitting Vehicle-to-Everything (V2X) messages on a SLRB according to whether (Internet Protocol) IP based or non-IP based V2X messages are to be transmitted on the SLRB, wherein the header compression and decompression is used if IP based V2X messages are to be transmitted on the SLRB and the header compression and decompression is not used if non-IP based V2X messages are to be transmitted on the SLRB.