Performance Analysis Of Diversity Combining With OFDM

Abstract

Wireless communications is the fastest growing segment of the communications industry. There is always a greater demand for capacity, reliability and also need to integrate voice, data and other type of traffic over radio channels. There are many ways to solve all these problems, such as OFDM, Spread spectrum techniques and Antenna arrays. In Wireless communications, the effect of channel fading and co-channel interference is very high. So we need diversity techniques which are used to mitigate all these effects. Indeed, diversity techniques at the receiver, in which two or more copies of the same information bearing signal are combined skillfully to increase the overall signal-to-noise ratio (SNR), still offer one of the greatest potential for radio link performance improvement to many of the current and future wireless technologies. This dissertation develops a mathematical framework for analyzing the average bit error rate performance of selection diversity combining, maximal ratio combining and optimum combining schemes with binary phase-shift keying (BPSK) modulation over independent and identically distributed Rayleigh fading channel with OFDM as multiple access technique. The need of high speed and reliable digital wireless communication which includes not only cellular phones but devices such as wireless modems, high definition television (HDTV) and digital radios. The need of high speed data transfer is catered by the orthogonal frequency division multiplexing (OFDM) and the performance of the system which is dictated by random fluctuations in the amplitude of the received signal is enhanced by using maximal ratio combining (MRC) and optimal combining (OC) diversity combining technique. Here we explore the system performance having receiver antenna diversity along with OFDM in Rayleigh fading environment. The performance of system is evaluated in terms of signal to noise ratio (SNR) and bit error rate (BER) probability. The simulation result shows that the performance ofOFDM system in Rayleigh fading in terms of SNR can be improved by using MRC and OC.