A simplified advantage ACE and PSO algorithm for PAR reduction in STBC MC-CDMA systems

Abstract

As to the high Peak-to-average ratio (PAR) of Space Time Block Coding Multicarrier Code Division Multiple Access (STBC MC-CDMA) systems, a simplified advantage Active Constellation Extension (ACE) and Particle Swam Optimization (PSO) algorithm is proposed. The algorithm first according to the baseband physical model of STBC MC-CDMA system, signal structure and matrix, the signal peak to average ratio of existing problems go to analyze. Then the signals are processed by the improved ACE algorithm, that QAM symbol on MC-CDMA subcarriers was be as complex signal, constellation points correspond to the constellation, the constellation points of modulation symbol are added offset ( time offset vector called trial cut peak vector ). And then using PSO algorithm to find the optimal test cut peak threshold, thus PAP of each subcarrier respectively as the trial cut peak threshold. Finally, through iterative search get PAP optimal trial minimum cut peak threshold, to meet the preset peak to average index. The simulation results and theoretical analysis indicates that the PAR of STBC MC-CDMA system can be efficiently reduced using the new algorithm, these methods can work well on the lower SNR input signals.