Abstract: The iterative multi-code detection for LAS-CDMA(large area synchronization-code division multi-access) system based on MAP(maximum posterior probability) criterion is studied in this paper. It interchanges the soft information between multi-code detection and channel decoder each other for several times. The iterative detector for non-binary modulation in multi-path fading channel is proposed and the simulation results indicate that the proposed detector can even achieve single-code transmission performance when the iteration times is higher than 3 for QPSK(quadri phase shift key) modulation.

Key words: iterative multi-code detection, soft information, iterative gain, single code transmission