Abstract: The aim of the paper is to improve the performance of QAM which is, one of the widely used modulation technique in the digital wireless communication that founds applications in DVB-T, DVB-C, modems, HSPA, LTE, LTE-A, microwave, and satellite systems, over a fading channel. Quadrature amplitude modulation (QAM) is a widely used method for transmitting digital data over the bandpass channels. In a communication channel, fading is one of the major issues among all, which degrades the performance of the systems to a great extends therefore it is necessary to reduce the effect of fading in order to improve the performance of the system in terms of bit error rate. Since the errors are introduced by the transmission medium we need to use a method that can be used to detect the errors and correct the errors. In order to achieve this, the error detection techniques and error correction techniques are used. These techniques increase the bandwidth requirement, but they provide reliable communication. An Almouti 2 X 2 STBC diversity technique is use to scale down the effect of fading whereas for error detection and correction the Reed-Solomon codes are used and the error rate is improved by the Interleaver. The model is implemented and investigated using Simulink (MATLAB) simulation. Firstly the performance of the QAM is analyzed over a fading channel then the performance of QAM along with RSBC, Alamouti STBC and Interleaving is compared with it, to comment on the benefits of the applied techniques.
Keywords: Bit error probability, DVB-T, LTE, LTE-A, QAM, RSBC, STBC, and Interleaver.