BER Performance Analysis of Rake Receiver in Rayleigh Fading Channel for UMTS environment

The goal for the third generation of mobile communications system is to integrate a wide variety of communication services such as high speed data, video and multimedia traffic as well as voice signals. Under the Universal Mobile Telecommunication System (UMTS) environment the Third Generation (3G) has many advantages such as highly efficient spectrum utilisation and variable user data rates. In this paper, we present the bit error rate (BER) performance analysis of Rake Receiver under UMTS environment with BPSK modulation technique and the convolutional coding at the transmitter and viterbi decoding at the receiver side. The Standard Gaussian Approximation (SGA) is used to evaluate the performance of Rake Receiver over a frequency selective Rayleigh fading channel. The data is modulated, encoded, spread and transmitted through a frequency selective Rayleigh fading channel. The transmitted signal is corrupted by multiple access interference, and is further corrupted by AWGN at the receiver. In the receiver, dispreading, decoded and demodulated. Rake Receiver, directive antenna are employed to improve the system performance. We examined the BER performance of Rake Receiver with, varying the number of users, spreading factor, Rake fingers, Interfering Cells, and the value of directivity of antenna at base Station. From the results we have seen that the BER performance of Rake Receiver is affected by varying these parameters and gives useful results. Index Terms -UMTS, DS-CDMA, Rake Receiver, Maximal Ratio Combining (MRC), Multipath channel , Directive antennas .