Mimo Ofdm Systems Using a Common Training Signal

This paper presents a common training signal design and corresponding estimation methods for carrier frequency offset and frequency-selective channels in MIMO OFDM systems. In designing the common training signal, a training signal structure which yields low complexity estimation methods is developed while the optimality of the training signal is maintained. Frequency offset estimation is based on the best linear unbiased estimation principle while channel estimation is based on the least squares (also maximum likelihood) approach. The proposed training signal and estimation methods can be applied to systems with pilot-only training signals as well as those with pilot-data multiplexed signals. The estimation range of the frequency offset can be flexibly adjusted. The performances of the proposed methods are very close to the Cramer-Rao bounds or theoretical minimum mean square error.