Abstract: The aim of the paper is to analyze the performance under various schemes and coding techniques for one of the most widely used modulation technique for wireless & mobile communication applications i.e. QAM (Quadrature Amplitude Modulation) in Rayleigh fading channel. First of all, we observe and analyze the effect of Rayleigh fading on the communication channel using QAM (Quadrature Amplitude Modulation) technique that can provide the higher rate of transmission without any incremental changes or variation in the bandwidth of the utilizing wireless communication systems. Whereas the performance of any modulation technique is measured on the basis of or in terms of its bit error probability therefore we find the performance of QAM in fading channel in terms of its bit error probability then we will try to improve & observe the effect on the value of bit error rate for the QAM technique by employing various schemes and coding techniques like Reed-Soloman block coding, interleaving and almouti STBC. In order to overcome the fading which is one of the major problems in the wireless communications, a diversity modulation technique is used for the efficient transfer of message signals whereas for error detection and correction the Reed-Solomon codes are used and the error rate is improved by the interleaver.
Keywords: Bit error probability, QAM, STBC, and Interleaver.