The Demodulation/Decoding Algorithm of PCMA Mixed Signals Based on Iteration Processing

To separate the Paired Carrier Multiple Access (PCMA) signals, a joint linear Minimum Mean-Square Error (MMSE) equalization and soft decoding iteration demodulation/decoding algorithm is proposed in this paper, which is based on the realization of the channel parameters estimation and the interference cancellation. In the course of equalization, the algorithm exploits the feedback prior statistics after decoding to improve the performance of demodulation, with special emphasis on the information interaction between equalization and decoding and the impact of the parameters estimation error on the performance of demodulation. Simulation results show that, with Turbo Product Codes (TPC) codes whose subcode is (64,57,4) expand BCH codes, a gain of about 4 dB in signal-noise ratio can be obtained after two iterations for QPSK signals at a bit error rate of 10-3; Moreover, the bit error rate can be promoted by at least two orders of magnitude after two iterations, when 8PSK modulationis exploited andEs/N0 is more than 20 dB.