A Space-Time Spreading Assisted Multicarrier DS-CDMA System using OVSF Codes Employing Adaptive Mode Switching Thresholds and Adaptive Modulation

Abstract

The Concept of Space-Time Spreading (STS) assisted, Adaptive Quadrature Amplitude Modulation (AQAM) aidedMC DS-CDMAis introduced. The AQAMmode-switching thresholds are determined using an on-line real-time Bit-Error-Ratio (BER) based learning procedure. Four different schemes were studied, designed for maintaining a given target BER of 10?2, 10?3, 10?4 and 10?5 both with and without turbo channel coding. The effect of using different number of STS antennas ranging from1 to 8 was also characterized in terms of the achievable effective throughput, characterising the associated system design trade-offs