Analysis Of CDMA System Capacity And Performance Estimate For Space-Time Block Codes

CDMA digital cellular mobile system has remarkable communication performence. It has been one of the hottest research topics in recent years,This thesis mostly researches the up-link capacity of CDMA system,and space-time block coding technology which can increase the down-link capacity.Firstly,this thesis introduces the characteristics of CDMA system in a nutshell.lt points out that CDMA is a system limitted by the interference, and the capacity of CDMA has the soft-characteristic.Then the pole point of capacity and the factors which affect it are presented. Whereafter, this thesis describes the relationship between the block probability and Erlang capacity ,and analyses the Erlang capacity using two different methods.This thesis discusses the factors which effect the Erlang capacity of system. The Erlang capacitis are given under every conditions to direct CDMA network planning.This thesis points out that soft switch is an important characteristic of CDMA system. soft switch can help to increase the up-link capacity.But it also can burden the down-link,because the down-link capacity will decrease with the amount of soft switch increasing.In order to improve the down-link performance,researchers have advanced space-time coding technology. At the end of this thesis, a method of estimating the performance of space-time block codes is proposed.And the decoding performence of system is analysed.