Effects of Antenna Correlation and Mutual Coupling on the Carrier Frequency Offset Estimation in MIMO Systems

In practical multiple-input multiple-output (MIMO) systems, due to the close proximity among the antennas, the channels between different transmit and receive antennas are spatially correlated. Besides spatial correlation, closely placed antennas also experience mutual coupling among the antennas, which is due to the interaction of electro-magnetic fields at different antennas. In this paper, we present a study on the effects of spatial correlation and mutual coupling and in particular, their impacts on the performance of the carrier frequency offset (CFO) estimation in MIMO systems. The simulation results show that spatial correlation degrades the performance of the CFO estimation. Mutual coupling has two effects. Firstly it reduces the spatial correlation, which is beneficial. On the other hand, it also reduces the power of the desired signal, which is detrimental. Simulations results show that the combined effects of mutual coupling introduces additional degradation on the CFO estimation.