Synchronous Bounded Delay Coding for Input Restricted Channels

Consider the class of input restricted channels whose constraints can be modelled by$nite state machines. This paper treats the problem o f constructing3xed rate (synchronous) codes for such channels subject to a constraint that the coding delay be bounded by a parameter M. M is the maximum number o f information symbols required by the coder in choosing a word during transmission. 1. Introduction In many digital transmission and recording systems, considerations such as spectral shaping, self-timing, and limitations on intersymbol interference require that, before modulation, the data be mapped onto a sequence with special properties. Such suitable sequences often define discrete noiseless channels of the type considered by Shannon [l] in which restrictions are represented by finite state sequential machines. In practice, a common additional requirement is that the encoding of the binary data onto the channel sequence must be synchronous. By this is meant that the bit per symbol ratio (the coding rate) is constant over each word.