Time Domain Channel Estimation for MIMO-FBMC/OQAM Systems

In this paper, a general preamble-based time domain channel estimation model for multiple-input multiple-output (MIMO)-filter bank multicarrier (FBMC) system based on offset quadrature amplitude modulation (OQAM) is derived. In contrast to the conventional frequency domain interference approximation method (IAM)-based channel estimation model, the derived time domain model does not require symbol time to be sufficiently longer than the maximum channel delay spread, viz. the derived time domain model does not require the channel to be frequency flat. Based on the time domain model, the weighted least squares (WLS) and minimum mean square error (MMSE) channel estimators for MIMO-FBMC/OQAM systems are investigated. The Cramer-Rao lower bound for the WLS, MMSE and IAM estimators are derived. It is shown numerically that all the estimators achieve their respective bounds, and the proposed WLS and MMSE estimators significantly outperform the existing IAM channel estimator. The comparison of the bit error rate performance of the aforementioned estimators also validates our work.