Adaptive Coding for Wireless Spread-Spectrum Communication Systems

Protocols for adapting the rate of an error-control code in direct-sequence or frequency-hop spread-spectrum packet radio networks are evaluated for static channels and channels with time-varying parameters that are modeled as finite-state Markov chains. The performance of our protocols is compared with the performance of an ideal protocol that has perfect channel-state information and employs a set of capacity-achieving codes of the same rates as the codes available to our protocols. The statistics used by our protocols for adaptation are derived from the demodulator and decoder in the receiving radio, and they are provided to the transmitting radio by a few bits that are included in each acknowledgment packet