Method and apparatus for handling multiplexing of sidelink reference signal in a wireless communication system

A method of a first device, comprising:

• receiving a configuration of a first sidelink resource pool from a network for sidelink data transmission and/or sidelink reference signal;
• performing a new sidelink data transmission for transmitting a sidelink data packet to a second device;
• triggering a first sidelink reference signal transmission based on a signaling sent from the second device or based on an upper layer of the first device;
• and
• determining whether to multiplex the first sidelink reference signal transmission with a first sidelink data retransmission based on whether the first sidelink reference signal is available for the second device and performing the first sidelink data retransmission, for transmitting the sidelink data packet to the second device.

A first device, comprising:

• a memory;
• and
• a processor operatively coupled with the memory, wherein the processor is configured to execute a program code to:
• receive a configuration of a first sidelink resource pool for sidelink data transmission and/or sidelink reference signal;
• perform an initial sidelink data transmission for transmitting a same sidelink data packet;
• and
• perform a first sidelink data retransmission, for transmitting the same sidelink data packet, with multiplexing a first sidelink reference signal transmission, wherein the first sidelink reference signal transmission is available or triggered after the initial sidelink data transmission.