Application of high-rate tail-biting codes to generalized partial response channels

The performance of high-rate tail-biting convolutional codes serially concatenated with generalized partial response channels is studied. The effect of precoders on the overall performance is investigated. Extrinsic information transfer charts are used to guide the selection of appropriate tail-biting codes and precoders. Simulation results for a magnetic recording system modeled as a serial concatenation of tail-biting codes with a generalized partial response channel are presented. In particular, rate-8/9 and -16/17 short- and long-block-length tail-biting codes are studied. In the former case, hard-decision decoded interleaved Reed-Solomon (RS) codes are used as the outer-most code, whereas in the latter case the sector-size tail-biting codes replace the RS codes traditionally used in storage systems. The results indicate that high-rate tail-biting codes deliver significant performance gains when used in conjunction with a rate-1 precoder and iterative detection/decoding. The results also show that long tail-biting codes can outperform hard-decision decoding of RS codes by 2 dB at a sector error rate of approx. 10^-4