A novel low rank LMMSE channel estimation method in OFDM systems

Abstract

Orthogonal frequency division multiplexing (OFDM) has been widely used in modern wireless communication systems. In OFDM scheme, channel estimation method is a key technology in improving the accuracy of the channel estimation and the system performance. There are many channel estimation methods in OFDM system. The least square (LS) channel estimation method is relatively simple but it is susceptible to the noise of the wireless channel. The linear minimum mean square error (LMMSE) and approximate LMMSE (ALMMSE) channel estimation methods provide good performance but are much more complex than conventional LS method. This paper proposes a novel low rank LMMSE method to simplify the filtering matrix in LMMSE method and diagonal matrix in ALMMSE method. Performance comparison is shown to verify the effectiveness of the proposed low rank channel estimation method. LMMSE and ALMMSE channel estimation methods are better than LS method, and LS method is the worst. Except the ideal channel estimation method, the low rank LMMSE channel estimation method provides the best bit error rate (BER) performance in cyclic prefix — OFDM (CP-OFDM) system. It simplifies the calculation of channel auto-correlation matrix and provides superior system performance over multipath channel conditions.