BER PERFORMANCE ANALYSIS OF OFDM-BPSK, QPSK, QAM OVER RAYLEIGH FADING CHANNEL & AWGN CHANNEL

Bit error rate is a key property of the digital communication system. Various types of modulation methods like ASK, BPSK, QPSK are used in the digital information transmission system. BER can be demarcated as the number of received bits of a data stream over a communication channel that can be affected due to noise, interference and distortion or bit synchronization errors. This paper mainly focuses the performance of OFDM -BPSK,-QPSK and -QAM system by using forward error correcting codes (convolutional, reed Solomon coding as well as concatenated coding) schemes. These codes are normally used to encode the data stream that can be passed through communication channels resembling AWGN channel, Rayleigh fading channel, Ricean fading, log-normal shadow fading etc. We have adopted AWGN channel, Rayleigh fading channel. We have illustrated the basic OFDM and associated modulation methods to improve the performance of OFDM for wireless communications (OFDM). We also have performed various simulations in Matlab to find out the best BER performance of each of the Convolutional and Reed-Solomon codes and used these best consequences to model the RS-CC concatenated codes. By concatenating two different codes we can get the effect of improving the total BER due to benefits of RS codes which are supportive in correcting burst errors, whereas convolutional codes are good enough for correcting random errors that appear in noisy channels.

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