Particle-Swarm-Optimization based turbo multiuser detection for STBC MC-CDMA systems

In this paper, we propose a near-optimal, reduced-complexity turbo multiuser receiver for space-time block-coded multi-carrier code division multiple access (MC-CDMA) uplink systems over frequency selective fading environments based on particle swarm optimization (PSO) algorithm. The soft-input soft-output (SISO) multiuser detector based on a posteriori probability (APP) algorithm can achieve optimal performance but with an exponential computational complexity. The novel SISO multiuser detector employs modified PSO algorithm, which has better global search capability and faster convergence compared with other heuristic algorithms. The proposed modified PSO algorithm is efficient to search for the candidate list, and then produce the approximate APP information. The new scheme can provide a bit-error-rate (BER) performance that is very close to maximum-likelihood (ML) detection with a significantly lower complexity.