Protocols that were proposed recently for adapting the error-control code from packet to packet in a frequency-hop packet radio network are evaluated for use on channels for which the fading distribution has fixed or slowly varying parameters. The protocols do not require channel measurements or pilot signals; instead, the receiver derives the necessary adaptation control information from its decoder during of the reception of each packet. The throughput achieved by each adaptive-coding protocol when it is used with a family of turbo product codes is compared with the capacity limit and with the throughput that is obtained from a hypothetical ideal protocol that is given perfect channel state information.

Alternative protocols are presented for adapting the code from packet to packet in a mobile, wireless, ad hoc network that employs frequency hopping, coherent or noncoherent demodulation, and soft-decision decoding on channels with time-varying propagation loss and time-varying partial-band interference. The protocols can be employed with a wide range of codes and decoding algorithms. No channel measurements are needed, and no external side information is supplied to the receiver. Performance results are provided for packet transmissions that employ turbo product codes. The protocol performance results are compared with capacity limits and with the performance for hypothetical ideal protocols that use perfect channel-state information to select the codes that maximize the expected throughput.

Alternative decoding methods are described and evaluated for use with a commercial turbo product code chip that is employed for error control on slow-frequency-hop spread spectrum wireless communications. One strategy is based on parallel decoding in two independent decoders, and another employs a single encoder with adaptive scaling of the sift decisions at its input. Performance results for such decoding strategies are compared for packet transmissions over channels with partial-band interference. When coupled with the development and use of side information in the frequency-hop receiver, these decoding strategies greatly enhance the performance of turbo product codes and make them competitive with parallel-concatenated turbo convolutional codes.