Performance analysis for smart antennas with orthogonal frequency division multiplexing based wireless networks

Abstract

The aim of this thesis work is to design a smart antenna based receiver in an Orthogonal Frequency Division Multiplexing (OFDM) system to improve the system performance and to reduce the computational complexity. OFDM is a special form of multi-carrier transmission that promises a higher data rate and greater resilience to severe signal fading effects at a reasonable level of implementation complexity. OFDM with multiple receiver antennas combine the different receiver signals. This type of OFDM system minimizes fading effects and thereby shows significant improvement in the system performance. However, each of the receivers has its own Fast Fourier Transform (FFT) Block, so the system complexity increases by the combination of receiver signals. To reduce the complexity of the OFDM system, a smart antenna system based Pre-FFT Maximum Ratio Combiner (MRC) is proposed. In the proposed scheme, only one FFT block is used instead of multiple FFT blocks in the receiver end. The received signal are weighted and combined before FFT processing. As a result, the number of FFT blocks reduces and the computational efficiencyincreases. A mathematical model of the proposed system is developed and the analytical formulation of Bit Error Rate (BER), channel capacity and throughput are also presented. Finally, the. performance of the pre-FFT MRC receiver and single receiver are evaluated and compared in terms of BER and other parameters. Computer simulation result shows a significant improvements in Signal-to-Noise.Ratio (SNR) for the proposed receiver.