Iterative timing recovery via soft decision metrics of low-density parity-check decoding

Abstract

An efficient scheme for iterative timing recovery via soft decision metrics (SDMs) of low-density parity-check (LDPC) decoding is presented. This scheme employs new metrics from LDPC decoding to overcome the difficult problem of timing synchronisation at low signal-to-noise ratios. It also obtains accurate timing acquisition with a search window-aided Nelder–Mead simplex algorithm by maximising the sum of the absolute values of the SDMs. The whole scheme is implemented, and our algorithm is concatenated with the Mueller–Müller algorithm, which performs timing tracking with LDPC decoding feedback. Our scheme has global convergence, moderate complexity and good performance. The simulation results indicate that the performance of the LDPC-coded binary phase shift keying system with rather large timing errors is within 0.1 dB of the ideal code performance at the cost of some computation and storage resources.