The present invention relates to a wireless communication system, and more particularly, to a method and apparatus for receiving information on a number N of a code block group defined for one transport block from a base station through an upper layer signal, receiving a first transport block including a plurality of code blocks from the base station through a physical layer channel, and transmitting HARQ-ACK payload including HARQ-ACK information on the first transport block to the base station. Preferably, a code block-based CRC is attached to each of the code blocks, a transport block-based CRC is attached to the first transport block, and the HARQ-ACK payload includes a plurality of HARQ-ACK bits corresponding to M code block groups for the first transport block.