Performance Analysis of Diversity Combining with Channel Coding

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 Space-time coding, 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. The channel coding is a rudimentary technique, which used to transmit digital data reliably over a noisy channel and to improve the efficiency of information transmission. This thesis 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 channel coding. With channel coding the performance of diversity combining techniques has been improved than the uncoded diversity combining techniques. It has been shown that the coding gain for coded SC over uncoded SC is 4 dB for N=5 and 4.2 dB for N=6. It has been seen that coding gain obtained by using channel coding is excellent. Also, the coding gain for coded and uncoded MRC and OC has been computed. The coding gain for coded MRC over uncoded MRC is 1.6 dB for N=5, 6 and coding gain for coded OC over uncoded OC is 4.7 dB for N=5 and 5 dB for N=6 when the number of interferers taken as L=1 and coding gain for coded OC over uncoded OC is 7 dB for N=5 and 6.2 dB for N=6 when the number of interferers are equal and greater than the number of receive array element which is taken as L=18. So it has been shown that for a given BER coded signals required less SNR as compared to uncoded signals.