Simplified Channel Tracking for MIMO-OFDM Systems

Anass BENJEBBOUR  Yukinaga SEKI  Susumu YOSHIDA  

IEICE TRANSACTIONS on Communications   Vol.E86-B   No.10   pp.3013-3022
Publication Date: 2003/10/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technology
wireless,  MIMO,  OFDM,  channel tracking,  

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Multiple-input multiple-output (MIMO) wireless systems can realize large spectral efficiency and high performance communication links. For wideband transmissions, the combination of MIMO systems with orthogonal frequency division multiplexing (OFDM) has recently attracted a lot of attention and it is well known as MIMO-OFDM. In MIMO-OFDM systems, the overlapped signals over each subcarrier need to be separated by the receiver. For fading coefficients based receivers, the performance of the receiver depends largely on the accuracy of the estimated channel. Especially, when the channel varies with time, accurate channel tracking is needed. Conventional optimized channel tracking has large computational complexity because large matrix inverse computation is required. In order to reduce the complexity, a simplified channel tracking scheme assuming PSK modulation has been considered. However, such a simplified scheme is found to suffer from large performance degradation when applied to multi-level QAM modulation. In this paper, we derive a new simplified but improved channel tracking scheme for MIMO-OFDM systems that can be applied to both PSK and multi-level QAM modulation. The performance and the complexity of the proposed scheme are evaluated with comparisons to conventional schemes.