Compensation of ISI Accomplished by CMA Eqalizer in WCDMA Communication System

Abstract: Due to propagation delay differences from source to destination in various multipath traced by the signal, the pulse width of the received signal may increase from that of the transmitted signal. Propagation delay differences constitute dispersion which introduces Inter Symbol Interference (ISI).The errors induced by ISI results in reduced bit rate of the communication system. In order to enhance the overall system’s performance, equalizers are introduced which aim for minimizing the ISI to allow recovery of transmit symbols. This paper deals with Constant Modulus Algorithm (CMA) Equalizer, the blind adaptive equalizer, to decrease the Bit Error Rate (BER) of the Wide Band Code Division Multiple Access (WCDMA) downlink system thereby improving the system’s performance. Reduction in BER lessens the radiation effects that lead to several health hazards.

Keywords: Multipath propagation, ISI, Blind adaptive equalizer, CMA equalizer, WCDMA