Vahideh Vakil - Spread Spectrum Research lab, Radio Communication Center of Excellence, Electrical Engineering dep., Amirkabir University of Technology, Tehran, Iran
Hassan Aghaeinia

This paper investigates the application of Adaptive Modulation and Variable Spreading Factor (VSF) methods in Space-Time Spreading (STS)-based Code Division Multiple Access (CDMA) system to improve the data throughput of the system. In this contribution, the combination of these two adaptive rate transmission methods is recommended for STS-based CDMA system. The Bit Error Rate (BER) performance of the system against pre-despreading Signal-to-Noise- Ratio (SNR) is calculated for different values of Spreading Factor (SF) and different modulation modes. An analytical approach is then proposed to compute the throughput enhancement of the adaptive modulated-VSF system for non-frequency-selective Rayleigh fading channel.

CDMA, Space-Time Spreading, Throughput, Adaptive Modulation, VSF