Combating media noise for high-density optical recording

Media noise is the dominant noise that severely degrades the channel detector's performance for high-density optical recording. In this paper, we first propose a simple but general channel model for rewritable optical recording systems with media noise. We further develop various detection approaches to combat media noise. In particular, two novel modifications to the channel detector are proposed: i) monic constrained minimum mean square error (MMSE) based equalization with media noise considerations, and ii) a modified Viterbi detector (VD) accounting for data-dependent noise variance. The proposed modifications provide significant performance gain over the conventional detection approaches that are designed for additive, white and Gaussian noise (AWGN), without increasing the size of the VD trellis. Furthermore, a new constrained parity-check (PC) code and a data-dependent post-processing scheme are proposed based on the modified detection approaches. Simulation results show that compared to the system designed without considering media noise and without PC codes, the proposed scheme achieves an overall performance gain of more than 11 dB at high media noise levels.