Recognised by John Wozencraft, sequential decoding is a limited memory technique for decoding tree codes. Sequential decoding is mainly used as an approximate decoding algorithm for long constraint-length convolutional codes. This approach may not be as accurate as the Viterbi algorithm but can save a substantial amount of computer memory. It was used to decode a convolutional code in 1968 Pioneer 9 mission.
Sequential decoding explores the tree code in such a way to try to minimise the computational cost and memory requirements to store the tree.
There is a range of sequential decoding approaches based on the choice of metric and algorithm. Metrics include:
Algorithms include: