Error propagation evaluation for RLL-constrained DFE read channels

Decision feedback equalization (DFE) is a promising low-cost solution for signal detection in magnetic recording channels. In terms of the bit error rate after detection, (0,k)-DFE and MDFE (Multilevel Decision Feedback Equalization) are comparable to (0,k)-PR4ML. Error propagation, however, is one of the major concerns for all DFE approaches. In this paper, an analysis of error propagation for RLL-constrained DFE at all stages of data processing, including RLL decoder and error correction, is performed. To evaluate error propagation, a Markov chain is constructed that explicitly models any type of RLL constraints. From this model, a Markov chain, describing the error distribution inside the bursts, is derived and a relation between these chains and error propagation decay rate is established. Performance of interleaved ECC (Error Correction Code) is also evaluated. The results obtained are compared with those from simulation. By using the newly developed model, a special technique of equalizer design, aimed to reduce error propagation, is analyzed. The comparison between (0,k)-DFE and MDFE in terms of the bit error rate after ECC is also provided.