Adaptive-rate turbo product coding for frequency-hop transmission and time-varying partial-band interference

A protocol is described and evaluated for adapting the rate of a turbo code for frequency-hop packet transmissions over time-varying partial-band interference channels. The rate of the turbo code is adapted from packet to packet to optimize the throughput. In particular, the protocol is designed to use a high-rate code when there is little interference and a low-rate code when the interference occupies a significant fraction of the band, even though neither the transmitter nor the receiver know what fraction of the band contains interference. No external side information is provided to the receiver, and our scheme requires no additional redundancy (e.g., pilot symbols) in the data packet for the generation of side information. The information needed to adapt the code rate is derived form our adaptive decoding system, and the only feedback required from the receiver to the transmitter is provided by a few bits in each acknowledgment packet. Results on the performance of the protocol are given for turbo product codes.