A Novel Complex-Modulation Based Space-Time Spreading Scheme with More Than Two Transmit Antennas for MC-DS-CDMA Systems

摘要

Space-time spreading (STS) is a promising schemerncombining the ubiquitously employed code division multiplernaccess (CDMA) with the emerging space-time block codingrn(STBC) technique. Almost all research results reported so farrnmainly focus on the STS schemes based on the full-rate STBC,rnwhich use either only two transmit antennas or real-modulations.rnHowever, the complex-modulation based STS systems with morernthan two transmit antennas, despite their much better spectrumrnefficiency and error performance, hardly receive any attention.rnTo remedy this deficiency, in this paper we propose a complexmodulationrnbased STS scheme with more than two transmitrnantennas for MC-DS-CDMA systems. We also develop thernperformance analysis frameworks to evaluate the bit-error-rate (BER)rnand throughput of the proposed scheme and other representativernschemes. The simulation results obtained verify the analyticalrnfindings. Both analytical and simulation results show that ourrnproposed scheme can achieve much lower BER and much higherrnthroughput as compared to their counterparts using realmodulationrnbased STS systems.