A Hybrid Coding Scheme for Discrete Memoryless Channels*

Abstract

We consider a coding-decoding scheme which can permit reliable data communication at rates up to the capacity of a discrete memoryless channel, and which offers a reasonable trade off between performance and complexity. The new scheme embodies algebraic and sequential coding-decoding stages. Data is initially coded by an algebraic (Reed-Solomon) encoder into blocks of N symbols, each symbol represented by n binary digits. The N n-bit symbols in a block are transmitted separately and independently through N parallel subsystems, each consisting of a sequential coder, an independent discrete memoryless channel, and a sequential decoder in tandem. Those coded n-bit symbols which would require the most sequential decoding computations are treated as erasures and decoded by a Reed-Solomon decoder. We show that the hybrid technique reduces the variability of the amount of sequential decoding computation. We also derive asymptotic results for the probabilities of error and buffer overflow as functions of the system complexity.