Self-Synchronizing Sequential Coding with Low Redundancy
Peter G. Neumann · Bell System Technical Journal · 1971
In this paper, we present sequential codes which have interesting properties in three respects. First, these codes may be used to achieve low redundancy (e.g., bandwidth compression through coding) by employing a multiplicity of variable-length codes to encode transitions between successive source symbols. Second, the coding complexity is surprisingly low. Third, many of these codes have exceedingly good intrinsic recoverability properties following errors. These codes compare favorably with a difference code environment in which the differences between successive source symbols are encoded. The scope of the sequential codes presented here includes, but is much wider than, difference code schemes. Where comparable, the sequential codes have slightly greater complexity and may have lower redundancy. They normally have vastly superior error recovery. These codes are applicable in situations such as video transmission in which the message source is highly correlated and where errors can be tolerated for a short period of time.