Research On The Technology Of High-speed Data Transmission In Cdma2000and WCDMA Systems

In today’s radio communication, users have been pursing the high quality and high speed datarates at anytime and anywhere. With the increment of users, the limited spectrum resourcesconstrain the development of communication more and more, code division multiple access(CDMA) technology with potential capacity is largely solved this problem. However, for practicalsystems, the performance of CDMA can be significantly degraded due to the interference producedby multiple access and multiple path propagation, all of the spreading codes of a spreading factor(SF) can not be used as the address code. This paper analyse the relationship between the spreadingfactor length and the number of available address codes, and a conclusion is drawn that theavailable number of address codes is less than that provided by the SF. The results of numericalsimulation for the capacity of CDMA system support the previous conclusion largely. Themulti-code transmission technology is not practical perhaps.cdma2000and WCDMA are two3G technologies used widely, and they share the same goal,which is to provide users with better service in all respects. To provide the enhanced support forwireless downlink data services, High Speed Downlink Packet Access (HSDPA) was standardizedin3GPP. It offers peak data rates of up to14.4Mbit/s with5MHz bandwidth for radio interface. Atthe same time, Evolution-Data Only (EV-DO) was standardized in3GPP2to provide up to4.9Mbit/s throughput with1.25MHz bandwidth. However, there are some anomaly questions inthese two systems. Such as the code division multiplexing process for high speed data rate in theforward link of EV-DO is arguable, and whether HSDPA technology can support the high data ratesof14.4Mbit/s by CDMA. Those answers would be given in this thesis. In addition, commercialoperations and developments on those two systems used by China Telecom and China Unicomseparately were further elaborated.