Sequential Decoding of Convolutional Codes

This article surveys many variants of sequential decoding in literature. Rather than introducing them chronologically, this article first presents the Algorithm A, a general sequential search algorithm. The stack algorithm and the Fano algorithm are then described in details. Next, trellis variants of sequential decoding, including the recently proposed maximum-likelihood sequential decoding algorithm, are discussed. Additionally, decoding complexity and error performance of sequential decoding are investigated, followed by a discussion on the implementation of sequential decoding from various practical aspects. Moreover, classes of convolutional codes that are particularly appropriate for sequential decoding are outlined.