ANALYSIS OF REDUCTION IN COMPLEXITY OF MULTIPLE INPUT- MULTIPLE OUTPUT-ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING SYSTEMS WITH CARRIER FREQUENCY OFFSET ESTIMATION AND CORRECTION

Abstract

Orthogonal Frequency Division Multiplexing (OFDM) is a promising research area in Wireless Communication for high data rates. The Multiple Input-Multiple Output (MIMO) technology when incorporated with the OFDM system promise a significant boost in the performance. But, the MIMO-OFDM systems are very sensitive to Carrier Frequency Offset (CFO) as it deteriorates the system performance with the rise of Inter-Carrier-Interference (ICI). A theoretical analysis to evaluate the performance of Orthogonal Frequency Division Multiplexing (OFDM) systems is done here, under the combined influence of Phase Offset and Frequency Offset over Rayleigh, Weibull and Nakagami fading channels using Binary Phase Shift Keying (BPSK) Modulation. The analysis of increase in Bit Error Rate (BER) caused by the presence of Phase Offset and Frequency Offset is evaluated assuming Gaussian probability density function. Hence the estimation and correction of CFO plays a vital role in MIMO-OFDM systems. A method for CFO estimation and correction is analyzed in the MIMO-OFDM system with 16-QAM modulation. In non-pilot-aided systems the CFO acquisition is done using Maximum Likelihood Estimation (MLE) algorithm. The proposed scheme uses the same block for CFO correction of MIMO-OFDM symbols. Since the same phase calculation block is used for the ML estimation along with the acquisition, the computational cost and the complexity of implementation is reduced.