JFET_V3_N2_RP6 Abdel Rahman Al Qawasmi Ibrahim N. Abu Isbeih Journal on Future Engineering and Technology 2230 – 7184 3 2 35 40 Effectiveness, Spread Spectrum System, CDMA and TDMA transmission, Transmitted power, Noise immunity In this paper the effectiveness of code division multiple access (CDMA) and time division multiple access (TDMA) multiplexing using M-ary Frequency Shift Keying (MFSK) is considered. The approach is based on the comparison between these two types by calculating the bit rate, noise immunity and the transmitted power of Digital Communication System (DCS). The use of Wide-band CDMA instead of TDMA in Spread Spectrum Digital Communication Systems (SSDCS) using Spread Spectrum Signals (SSS) increases the bit rate and decreases the noise immunity of the system. This decrease can be compensated by increasing the transmitted power (signal to- noise ratio, SNR). November 2007 - January 2008 Copyright © 2008 i-manager publications. All rights reserved. i-manager Publications http://www.imanagerpublications.com/Article.aspx?ArticleId=664