Signal Space Detection for DVD Optical Recording

A signal space detector (SSD) based on a single hyperplane is proposed which offers nearly the same performance as the fixed delay tree search with decision feedback (FDTS/DF) for the digital versatile disk (DVD) channel. The FDTS/DF detector with a reasonable decision delay performs almost as well as the optimal maximum likelihood sequence detector (MLSD) due to the EFMplus modulation code that includes the d=2 minimum runlength constraint. The single-hyperplane approximation of the FDTS/DF detector is made possible by considering only the critical signal points in the three-dimensional signal space. When the jitter noise is significant, the slope of the hyperplane decision boundary can readily be adjusted to improve the performance beyond that of the standard FDTS/DF detector. We also provide analysis and simulation results that verify the performance advantage of the SSD over partial response (PR) based threshold and Viterbi detectors. The distance between the received signal in signal space and the single hyperplane can be interpreted as soft information. The soft SSD can be used along with iterative error correction codes, such as low density parity check codes (LDPC), resulting in large performance gains.