Methods and apparatus for transmitting Asynchronous Hybrid Automatic Repeat reQuest (ARQ) process identities in a wireless communication system. A linking scheme is established between at least two sets of process identities of two respective corresponding codewords. When a first process identity is selected from among a first set of process identities of a first codeword, a second process identity may be derived in dependence upon the first process identity and the established linking scheme. Finally, a first packet from the first codeword is transmitted using a first transmission channel indicated by the first process identity, and a second packet is transmitted from the second codeword using a second transmission channel indicated by the second process identity. In addition, a control message including only the first process identity is transmitted.