Carrier Frequency Offset Compensation for Distributed MIMO OFDM Systems

This paper focuses on the compensation of carrier frequency offsets (CFO) in multi-input multi-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems with distributed transmit antennas, where the CFOs are possibly different for each transmit antenna. Considering macroscopic fading and multipath Rayleigh fading, the average power of the intercarrier interference (ICI) caused by the CFOs is derived. The optimal CFO compensation value is then obtained by maximizing the signal-to-interference-and-noise ratio (SINR) before MIMO detection. It is shown that the optimal CFO compensation value should be located between the minimum and maximum value of the CFOs and depends on the CFOs and the macroscopic fading of all the transmit antennas. The performance of the CFO compensation is evaluated for a MIMO OFDM system with two transmit antennas and two receive antennas using zero-forcing (ZF) detection. Simulation results show that the symbol error rate (SER) performance is significantly improved by using the proposed optimal CFO compensation value to compensate for the CFOs.