MIMO-OFDM Training Signal Design in the Presence of Frequency Offset and Phase Noise

All existing training signal designs for channel estimation in OFDM systems neglect phase noise or both frequency offsets and phase noise. In practice, frequency offset and phase noise are unavoidable and can seriously degrade the performance of OFDM systems. In this paper, we address the problem of designing optimal training signals for the estimation of frequency-selective channels in MIMO OFDM systems with frequency offset and phase noise. Analytical and simulation results for the corresponding channel estimation mean square error are presented. Channel estimation performance is more sensitive to frequency offset and phase noise in MIMO than in SISO OFDM systems. The performance improvement achieved by the proposed training signals becomes more significant for moderate-to-high values of SNR, frequency offset, and phase noise level