This project is exploring two simple and powerful coding ideas. The first involves staged power transfer from an outer to an inner code and can find use on both trellis and conventional convolutionally coded systems. This new technique not only improves the performance of concatenated coding systems in their usual operating regime, i.e., very low decoded error rates, but also extends their use to the less stringent requirements of uncompressed images or speech where decoder complexity and short delays are important. Satellite based mobile telephone or data service could benefit immediately from these techniques. The second idea is a method of sharing parity checks among the members of a set of Reed-Solomon codewords. The effect is a decrease in the amount of reduncancy required, i.e., an increase in the rate of the code. The greatest need for this technique comes from systems where the symbol size is in some way dictated by the channel, e.g., an 8 bit Reed Solomon code with 256-ary p.p.m. on a photon counting optical channel. Even if the symbol size is not constrained, i.e., larger Reed Solomon codes could be used, both the encoder and decoder complexity measured in operations per information bit of the new method appear to be lower for the same performance gain.
