Turbo decoding for high-rate concatenated parity-check codes on PRML channels

A simple turbo decoding scheme is proposed for partial-response (PR) channels by using high-rate parity-check codes as an outer error-correction code (ECC). The use of the simple parity codes enables a simplified and high-speed implementation of the a posterior probability (APP) decoder. Its key feature is an iterative decoding step for the parallel concatenation of two parity-check outer codes connected via an interleaver. The parity iterative decoding can provide the high-rate parity-check outer codes with superior correction capability for random error-events, so it can help to reduce the decoding latency. The combination of the serial turbo decoding for a modified E/sup 2/PR (ME/sup 2/PR) channel and the parity iterative decoding demonstrated a coding gain of 4-5 dB at a bit error rate of 1.0E-5 for a coding rate of 8/9.