A method for sidelink (SL) communication in an unlicensed frequency spectrum includes receiving a configuration for a SL transmission, monitoring a hybrid automatic repeat request-acknowledgement (HARQ-ACK) response in a physical sidelink feedback channel (PSFCH) according to the configuration for the SL transmission, performing a listen-before-talk (LBT) operation to gain access to a channel according to the HARQ-ACK response, and performing the SL transmission after the LBT operation.