Combine non-binary LDPC codes with M-ary orthogonal spread spectrum modulation

Low-density parity-check (LDPC) codes are playing more and more important roles in wireless communications due to their excellent error correction performance. In this paper, we study the combination of non-binary LDPC codes with M-ary orthogonal spread spectrum modulation for bandwidth efficient transmission over AWGN channel. Specifically, we investigate an algorithm for computing symbol soft metric based on Maximum a Posteriori Probability (MAP) criterion. To justify the performance of our proposed scheme, we made extensive simulations for various code rates and codeword lengths.