Performance Evaluation of MIMO-OFDM System by PAPR Reduction and Channel Estimation

Abstract

There are not limit of human desire so day by day we need much higher data speed to facilitate our need but every physical resources like frequency band, transmit signal strength are finite. Within the given limited resource higher data speed is accomplished by new proficiency called Multiple Input Multiple Output (MIMO), Orthogonal Frequency Division Multiplexing (OFDM) system. MIMO-OFDM fulfills the high data rate requirement through spatial multiplexing gain and improved link reliability due to antenna diversity gain. With this technique both interference reduction and maximum diversity gain are achieved by increasing number of antennas on either side. Performance of MIMO-OFDM system depends on various factors like channel characteristics, SNR, fading, etc. Among them peak to average power ratio (PAPR) and channel estimation are major parameters that must be primarily addressed. In the thesis various PAPR determining factors such as no of subcarriers, oversampling rate and modulation scheme are studied and their effects are analyzed. Clipping, coding, symbol scrambling, adaptive predistortion and DFT-spreading technique for PAPR reduction are thoroughly discussed. Furthermore, comparison among their characteristics is simulated in MATLAB and useful conclusion is delineated. Received signal in MIMO-OFDM system usually distorted by multipath fading. In order to recover the transmitted signal correctly, channel effect must be estimated and repaired at receiver. In the thesis several channel estimation method are mediated and appropriate solution is recommended. To relieve from overhead of training symbols, which significantly shrink the system bandwidth-efficiency, blind channel estimation algorithm is compared with training based channel estimation technique.