A problem associated with the use of variable-length source codes is that loss of synchronization may lead to extended errors in the decoded text. In this correspondence it is shown that some binary Huffman codes contain a codeword that resynchronizes the decoder regardless of the synchronization slippage preceding that codeword. Such codes are self-synchronizing in a probabilistic sense, yet require no additional system overhead. Some sufficient conditions are found for the existence or nonexistence of self-synchronizing Huffman codes for many classes of source probabilities. One of our results shows that many common languages can be encoded with self-synchronizing Huffman codes.

Large classes ofT-user codes for the binary adder channel are shown to be easily constructed by generalizing some previous results in two basic ways. The first is an iterative procedure; the second is by introducing an equivalence relation on such codes. Decoding algorithms are presented in both cases. The number of codes in the equivalence class of some previously defined codes is determined exactly.