Hybrid ARQ error control using sequential decoding

An important feature of ARQ sequential decoding is that a very low undetected error probability can be achieved without increasing significantly the complexity of decoding. Several ARQ sequential decoding algorithms based on the stack algorithm are considered. Analysis is done for a memoryless channel with noiseless feedback, and the emphasis is on evaluating the undetected error probability and the maximum throughput attainable with each algorithm. A time-out algorithm is analyzed and the parameters optimizing the performance of this algorithm are found. A new algorithm called the slope control algorithm, capable of achieving a better throughput than the time-out algorithm, is proposed. The algorithm is analyzed using random coding arguments, and the parameters maximizing the throughput for various conditions are found. All theoretical results are verified by computer simulation for a binary symmetric channel.