A Simple and Feasible Decision-Feedback Channel Tracking Scheme for MIMO-OFDM Systems

Yusuke ASAI
Wenjie JIANG
Atsushi OHTA

IEICE TRANSACTIONS on Communications   Vol.E90-B    No.5    pp.1052-1060
Publication Date: 2007/05/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e90-b.5.1052
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Advanced Transfer Technologies for the Next Generation Network)
MIMO,  OFDM,  channel tracking,  channel estimation,  Doppler frequency,  IEEE 802.11n,  wireless LAN,  frame aggregation,  

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This paper proposes a simple and feasible decision-feedback channel tracking scheme for multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems designed for wireless local area networks (LANs). In the proposed scheme, the channel state matrix for each subcarrier is tentatively estimated from a replica matrix of the transmitted signals. The estimated channel matrices, each derived at a different timing, are combined, and the previously estimated channel matrices are replaced with the latest ones. Unlike conventional channel tracking schemes based on a Kalman filter, the proposed scheme needs no statistical information about a MIMO channel, which makes the receiver structure quite simple. The packet error rate (PER) performances for the proposed scheme are evaluated on computer simulations. When there are three transmit and receive antennas, the subcarrier modulation scheme is 64 QAM, and the coding rate is 3/4, the proposed scheme keeps the SNR degradation at PER of 1e-2 less than 0.1 dB when the velocity of receiver is 3 km/h in an indoor office environment at 5 GHz band. In addition, compared to the conventional channel tracking scheme based on known pilot symbols, the proposed scheme improves throughput performance by 13.8% because it does not need pilot symbols. These results demonstrate that the proposed channel tracking scheme is simple and feasible for implementation in MIMO-OFDM systems based on wireless LANs.