MIMO-OFDM frequency offset estimation for Rayleigh fading channels

As the number of applications that make use of digital communication is increasing; the need of increased data rate and efficient use of the available bandwidth is also increasing. The use of Orthogonal Frequency Division Multiplexing (OFDM) technique in Multiple Input Multiple Output (MIMO) systems, often called as MIMO-OFDM systems helps to provide high spectral efficiency and increased data throughput. But, they are often subjected to synchronisation errors. Frequency synchronisation error in OFDM systems is caused by the Carrier Frequency Offset (CFO) which will result in loss of the subcarrier orthogonality leading to Inter Carrier Interference (ICI). In this paper, a comparison of the time domain and frequency domain CFO estimation techniques is done for the MIMO-OFDM systems for both flat fading and frequency selective multipath Rayleigh fading channels. Also a new Cyclic Suffix (CS) - based CFO estimation technique is proposed with improved CFO estimation range. The performance of the algorithms is evaluated through simulation in MATLAB.