Packet combining systems based on the Viterbi decoder

Abstract

Several packet combining schemes are presented for use in conjunction with the Viterbi decoder over stationary and time-varying channels. The first technique presented is an average diversity combiner. The averaged diversity combiner is then generalized to make use of packet weights either based on ideal channel state information or derived from side information generated by the Viterbi decoder. It is shown that the weighted diversity combiner using decoder side information performs almost as well as the system using ideal channel state information. All of the packet combining schemes discussed provide improved throughput and reliability performance relative to that provided by the standard type-I hybrid-ARQ (automatic-repeat-request) or FEC (forward error correction) systems. Performance bounds are derived for each of the combining schemes, and their tightness is verified through simulation results.<>