Simulations and Performance Analyses of Multi-user Alamouti’s Space Time Block Coded MIMO CDMA Systems

Abstract

This thesis explores Code Division Multiple Access (CDMA) systems and conducts a comprehensive study of its fundamentals. CDMA has already made a firm position in the arena of fast growing 3G communications and vanquished by reigning over other multiple access technologies, for its use of spread-spectrum technique and provision of providing a robust transmission by combating various channel impairments. Further advanced studies have been done on space time block coded CDMA systems for multi-user which yields a new standard for transmission over Rayleigh fading channels using multiple transmit antennas. The combination of space time block code and CDMA system has the aptitude of increasing performance in cellular network. With a simplistic approach, the performance of this system is compared with the typical CDMA system which manifests that, using space time block code and multiple transmit antennas for multi-user CDMA system provide remarkable performance without any need of extra processing or sacrifice in bandwidth. Along with space-time block code, space-time trellis code is also analyzed and compared theoretically on the basis of MIMO implementation, with extended performance evaluation. For further performance analyses, diversity techniques have been manifested and this insight has been comprehended by mathematically manipulating Alamouti’s transmit diversity scheme, which surely offers remarkable performance improvement, which, later, has been justified from the results obtained from simulations.