Sequential turbo decoding for PR-equalized magnetic recording channels

In this paper, we consider the use of sequential decoding methods to reduce the complexity of the channel decoder for turbo coded magnetic recording channels. The partial response equalized magnetic recording channel is suitably preceded to give a recursive structure for the channel trellis. The soft-in/soft-out twin stack decoding technique is then used to decode this recursive trellis. Simulation results show that the performance of the proposed decoding technique is within 0.6 dB for a PR4 channel and within 1.1 dB for a EPR4 channel in comparison to the BCJR decoder, while the complexity of the decoder decreases by a factor 1/(number of channel states).