Multiple access receiver based on hierarchical clusters/users detection using non-binary LDPC codes

A new scheme of detection for multiple access channel is investigated, which consists in the combining of PIC-like detection and joint decoding of LDPC codes. The joint decoding is first investigated through the use of LDPC codes over Galois extensions of binary field for the AWGN multiple access channel. It turns out that the (2,4)-regular GF(4)-based LDPC codes perform 2dB better than the binary regular LDPC. As second result, we point out that GF(4) is also the best suited field´s extension for this application. These preliminary results indicate that conjunction of PIC and joint detection could provide substantial improvement without any complexity growth of the emitter in a MC-CDMA like up-link framework.