Comparative Analysis of BER Performance under QAM-OFDM System Over AWGN and Rayleigh Fading Channel

The fast development of modern communication techniques, the demand for reliable high data rate transmission is increased signification, which stimulate much interest in modulation technique. The QAM is one of the adaptive modulation techniques that are commonly used for wireless communications. Different order modulations allow sending more bit per symbol and thus achieving higher throughput or better SNR are needed to overcome any interference and maintain a certain BER. This paper at developing a simulink model to simulate different types of QAM modulation and demodulation techniques at different bit rates. Orthogonal Frequency Division Multiplexing (OFDM) was originally developed from the multi-carrier modulation techniques used in high frequency military radios. Also we are used Orthogonal Frequency Division Multiplexing (OFDM) technique with AWGN channel and Rayleigh channel. Result presented in this paper the BER tool under Matlab R2013a is used to evaluate the performance of modulation technique through draw the BER versus SNR (Eb/N0). Keyword QAM, OFDM, AWGN, BER, SNR