Performance Analysis of Mimo of dm System in Fading Channel Using Relaying Techniques

Abstract

OFDM (orthogonal frequency division multiplexing) system is basically a large number of closely spaced orthogonal sub-carrier signals which are used to carry data on several parallel data streams or channels. In addition, the usage of multiple antennas at the transmitter and receiver side in wireless systems, is popularly known as MIMO technology. Both these technologies have rapidly gained in popularity over the last few years due to its powerful performance-enhancing abilities. Further, Rayleigh fading is one of the model which gives information about signal propagation in a radio environment. The assumption on this model is that the signal which propagates through a communication channel will vary randomly, or will subject to fading, according to a Rayleigh distribution. Rayleigh fading is basically applicable when there is no dominant propagation along a line of sight present in between the transmitter and receiver side. In this thesis, we have tried to collaborate the advantages of both the systems i.e. MIMO system and OFDM system to work as one system namely MIMO-OFDM system. We have conducted an extensive analytical based study of MIMO-OFDM systems in MATLAB. We tried to analyze the performance of MIMO-OFDM under Rayleigh fading channel in terms of BER and spectral efficiency. Further, we analyzed different relaying techniques with MIMO-OFDM system that will exploit system advantages. These relaying techniques were namely, amplify and forward, decode and forward and hybrid relaying techniques. We have tried to compare different relaying techniques in MIMO-OFDM system in terms of BER and spectral efficiency in three different modulation schemes namely BPSK, 16-QAM and 64-QAM.