Performance Analysis Of Cdma System Using Power Control Algorithm With Awgn Channel
G. Suganthi Brindha · i-manager s Journal on Communication Engineering and Systems · 2012
In wireless communication systems, fading is one of the major problems that cause the signal fluctuation so it cause the signal degradation at the receiver. One of the wireless communication types that experiences fading is CDMA[1,2]. The per formance of the wireless communication is greatly affected by Multipath fading. It can be exploited by using Rake type of receiver. Path loss is caused by dissipation of the power radiated by the transmitter as well as effects of the propagation channel. Path loss models generally assume that path loss is the same at a given transmit-receive distance. The RAKE reception is a technique which uses several baseband correlators called fingers to individually process multi-path signal components. Another problem that CDMA suffers is signal interference from other users because all users in CDMA system use the same frequency. Interference usually refers to the interaction of waves that are correlated or coherent with each other, either because they come from the same source or because they have the same or nearly the same By frequency. Diversity is the technic used to mitigate fading. Diversity can improve the quality of the received signal at the receiver. To combat other users' interference, power control is used to improve the CDMA system performance because power control can minimize the interference between users. In fading channel the Signal-to-Interference Ratio (SIR) varies according to the channel's response. The superposition of the multipath signals can be realized by the rake receiver which increase the output signal-to-noise ratio and also increase the power efficiency. The CDMA power control mechanism can be used to make the signal-to-interference ratio(SIR) nearly constant[3].The downlink performance of a CDMA system employs both open loop and closed loop power control. The open loop power control is performed at the mobile station based on the measurement of the downlink signals and it can compensate for the near far distance problem[5]. The closed loop power control is performed at the base station based on measurements of the SIR experienced at the base station and requires the