Study On The Performance Of Multi-Traffic DS/CDMA System And Diversity Technologies

The videos, voices,data combined traffic and high speed data are becoming more and more predominent in the future ,and how to efficiently transfer this multi-medium integrated-data is one of the researcher's interesting field .The CDMA system,which has striking advantages of anti-multipath fading,soft capacities and large capacities over FDMA and TDMA systems,has been focused by all of the countries. The CDMA system that would be used to transfer the multi-traffic and improve the performance with diversity is extensively studied for the multi-media and high speed data development in the paper. The main contents and new ideas include:The diversity technologies that widely used in mobile communication system are discussed,and the optimal receiving techniques in correlated fading channel and independent fading channel are studied.The Gaussian approximation method used in single traffic CDMA system is introduced ,at the same time the improved Gaussian method also discussed for greater accuracy ,when the active user load is small.However,the improved Gaussian method needs more complicated calculations. The simplified Gaussian approximation can be obtained,which has almost the same in accuracy but much less calculations than improved Gaussian approximation method .The single traffic CDMA system in Nakagami fading channel with RAKE receiver is investigated extensively. A closed form BER expression is obtained with arbitrary chip waveforms. At meantime ,the numerical results are presented The CDMA system with GSC receiver and multi-traffic is analyzed. The multi-traffic system includes not only the single system interference but also the interference between data and voices ,which limit the capacities of the system and cause the complexity of the power control .The system performance can be improved with GSC receiver .The multi-cell CDMA system capacity analysis is discussed in the paper.The related close expressions and the performance plots of multi-cell CDMA system's capacity are presented ,which clearly show the relationship of the capacity and voice users ,and data users,and activity factors.All the results discussed in the paper could be useful and valuable for the practical system design.