Extending acknowledgement messages from two states to at least three states is described, whereby such messages constitute a packet quality indication (PQI) reflecting quality or usability of the received signal. In an HARQ system, a transmitting station can flexibly select a better alternative for the next information to transmit on the basis of such PQI. One aspect includes determining how best to correct an unsuccessful packet transmission based on quality information about the specific packet. Implementing apparatus and procedures are described.