Efficient Detection and Decoding of Q-Ary LDPC Coded Signals Over Partial Response Channels

In this paper, the authors consider the ways for concatenating the Inter Symbol Interference (ISI) detector with a qary Low-Density Parity-Check (LDPC) decoder for transmissions over Partial Response (PR) channels. LDPC codes allow achieving performance close to the channel capacity in additive white Gaussian noise channels, while designing receivers employing these codes for transmissions over channels affected by ISI is still an open issue. Turbo equalization schemes are considered with a novel joint message-passing-based receiver, which is derived from a recently proposed joint algorithm for binary LDPC codes. Simulation results provide performance evaluation of these systems over three different PR channels, together with an analysis of the trade-off between error-rate performance and complexity.