Iterative soft detection of cochannel signals using ant colony optimization

We propose an iterative soft multiuser detection technique for detecting multiple BPSK modulated cochannel signals in Rayleigh flat fading environments. Ant colony optimization is used to produce soft estimates of the transmitted signals. Our attention is focused on the challenging case of overloaded transmission, where there are fewer receive antennas than transmitted cochannel signals. Simulation results show our approach can achieve near maximum likelihood (ML) performance at significantly reduced complexity for critically loaded systems, and it continues to provide good performance under overloaded scenarios.