Application of continuous error detection for joint equalization and coding for ISI channels

Intersymbol interference (ISI) distorts digital signals transmitted over band-limited channels. While solutions like decision feedback equalization (DFE) suffer from error propagation, sequence estimation methods have exponential complexity. We present a scheme that effectively reduces the complexity of sequence estimation by removing paths that are in error on the fly, using continuous error detection (CED). The number of symbols taken for detecting an error can be tuned based on the amount of redundancy available for the particular application. Simulations show that our scheme can bring about a factor of two reduction in complexity in the trellis of Yellin, Vardy and Amrani (see IEEE Trans. on Info. Theory, vol.43, p.409-25, 1997) and give about 0.5 dB performance improvement at the same complexity. CED can be implemented efficiently at low complexity in hardware and can enhance the performance of ARQ/FEC based digital transmission systems. This work presents the performance gains in a reduced state sequence estimation framework