A combined decoder for STBC and non-binary LDPC codes with spatial diversity

The main problem to apply the non-binary low-density parity (LDPC) codes in multiple-input multiple-output (MIMO) channel with a high order Galois field is to compute the log likelihood ratios (LLRs) for each transmitted symbol. The complexity of computation of LLRs grows exponentially with the number of the order of the Galois field. In this paper, we combine the space-time block coding (STBC) decoder with the LDPC decoder together to achieve the full diversity in MIMO channels. In order to reduce the complexity of computation of LLRs, the multiuser concept is used in our design. Consequently, the complexity grows only linearly with the number of the order of the Galois field. The simulations show that the BER curve exits an accepted gap (0-1 dB).