Systems and techniques relating to wireless communications are described. A described technique includes receiving signals representing wireless data transmissions that are based on a symbol, the received signals including one or more first signals and a second signal, where a decoded version of the one or more first signals previously failed to successfully resolve the symbol. The second signal can be transmitted in response to the one or more first signals failing to successfully resolve the symbol. The technique includes determining the symbol based on the received signals, where the determining places more significance to the second signal than the one or more first signals.