Performance Analysis of Hybrid Diversity Technique in TWDP Fading Channel

Abstract

In this technology driven era, tremendous growth in the mobile communication services has made possible for the people to exchange information (data, voice or image) with each other while they are on the move. These wireless systems have brought a revolution in the current market for their high data rates and performance enhanced features. One of the key issues affecting the performance of a wireless channel is the random variations in the signal strength which may be resulted due to some obstructions like buildings, trees, etc. or due to the movement of the mobile user. This leads to stochastic behavior of the radio channel. This thesis presents the need to obtain a clearer perception of channel characteristics and to model a system for combating fading and improving the system performance. Current wireless scenario where deployment of directional antennas, wide band signals and narrow band receivers is an essential requirement, an environment is formed which is correctly represented by TWDP (Two Wave with Diffuse Power) Fading model other than Rayleigh or Rician Model. It comprises of two LOS components in the presence of other diffusely propagating waves. A highly faded TWDP environment is discussed along with Hybrid diversity combining i.e. amalgamation of MRC and SC techniques. The effectiveness of this scheme is further evaluated by analyzing the system performance in terms of BER versus SNR. Analytical results are plotted in computer software MATLAB and various mathematical expressions are derived using MATHEMATICA tool to analyze the performance of system model for the same. th M i.e. receive antennas and R i.e. number of MRC receivers are varied in a Hybrid diversity system. Comparison is made between both Rayleigh and TWDP channels in terms of BER versus SNR. Modulation schemes such as BPSK and QPSK are applied on this Hybrid system model. The factual statement that TWDP fading forms a link which is worse than the link made by Rayleigh fading is demonstrated with the help of MATLAB simulations. Higher BER is observed considering TWDP channel and the need to consider this model in designing worst case communication scenario is shown in thesis.