Power Control in DS-CDMA Forward Linkin Mobile Channels

ABSTRACT: In this thesis, performance of Direct Sequence Code Division Multiple Access (DS-CDMA) in wireless cellular communication system is investigated using Closed Loop Power Control (CLPC).Power control is significant in a DS-CDMA system, which is to reduce Multiple Access Interference (MAI) and near-far problems. In CDMA, the entire mobile users share the same frequency band simultaneously. Hence, they all interfere with one another. The significance of CLPC is to maintain the received signal strength at the desired level. The desired values are set by Base Station(BS) in order to keep the Bit-Error-Rate(BER)at anacceptable level with minimum possible transmission power.System performance is demonstrated with BER comparisons. It is shown that CLPC optimizes transmission powersand improves the capacity of the system. The proposed power control scheme is based on estimated signal strengths. The performance of CLPC algorithm and the DS-CDMA system is examined in AWGN and fading channels. The simulations are implemented on MATLABsoftware environment. Keywords: Wireless cellular communication systems, DS-CDMA, Closed Loop Power Control. ……………………………………………………………………………………………………………………………………………………………………………………………………………………