Variants of the stack algorithm for the decoding of high rate codes by sequential decoding

A modified version of the Zigangirou-Jelinek (Z-J) stack algorithm for sequential decoding of high rate satellite communications codes is presented. The algorithm is based on a discarding threshold to eliminate unnecessary nodes for each path extension. A numerical simulation is used to find ways for reducing the complexity and memory requirements of the decoding algorithm without degrading error performance. The parameters used in the simulation were error rate, the average number of computations per decoded branch, the average number of nodes stored in the stack, and the average stack size per decoded block. It is found that large savings in decoder memory may be achieved at hardly any cost in error performance or computational variability.