Frequency offset compensation for spatial multiplexing MIMO-OFDM systems with distributed transmit antennas

This paper focuses on the compensation of carrier frequency offsets (CFO) for spatial multiplexing multi-input multi-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems with distributed transmit antennas, where the CFOs between the receiver and each transmit antenna are possibly different and the zero-forcing (ZF) detection is used. Rather than the conventional linear frequency-domain equalization method that involves computationally complex matrix inversions, we propose a CFO compensation method without need for matrix inversion by exploiting the underlying characteristics of ZF detection and assuming relatively small root-mean-square (r.m.s.) delay spread of the multipath channel. Simulation results show that the symbol error rate (SER) performance of the system is significantly improved by using the proposed CFO compensation method in the low delay spread case (i.e., channel A) of the three test environments in the ITU-R M.1225 channel model.