Error Correction for Voice Grade Data Communication Using a Communication Processor

A general purpose communication processor is investigated as a vehicle for decoding two specific classes of cyclic codes having properties appropriate for voice grade data communication channels. First, a model of a processor is described, and then it is used in conjunction with two cost metrics to measure the complexity of programming the decoding functions. No special Galois field (GF) arithmetic instructions are used. For decoding both Bose-Chadhuri-Hocquenghem (BCH) and Fire codes, a method which allows the encoding program to be used in the initial steps of decoding is given and evaluated. The evaluation indicates that both encoding and decoding, for voice grade data communication facilities, can be done in contemporary communication processors with core storage in the 1000 word range and instruction cycles in the microsecond range. In addition, the results show how the cost metrics vary with parameters such as the block length, the number of errors or the burst length correctable, and the block error probability introduced by the channel. Other conclusions, such as the areas in which significant improvements are needed and in which hardware assist can improve performance are drawn from data giving the relative costs of the elements of the decoding process.