Abstract: The pseudocode acquisition method based on iterative message passing algorithm (IMPA) is able to improve the acquisition speed greatly under the low complexity condition, but decrease fast in the poor SNR conditions. In the multiple input multiple output (MIMO) systems, it can weaken the multi-path fading, and improve the performance of the communication systems without increasing the spectrum resource and the transmit power. In this paper, the IMPA used in MIMO system is proposed, in which the diversity technique is adopted in the receiver side, the maximal ratio combining (MRC) method is used to combine the received signals, and then the IMPA is used to acquire the signals. Simulation indicate that the IMPA used in MIMO can improve the acquisition probability effectively without impacting acquisition speed, the acquisition probability can achieve 90% when SNR is -22dB, and the performance is better than the existing method.

Key words: IMPA, MIMO, MRC, Code acquisition