Open Access

Efficient Closed-Loop Schemes for MIMO-OFDM-Based WLANs

EURASIP Journal on Advances in Signal Processing20062006:091919

Received: 28 December 2005

Accepted: 13 August 2006

Published: 27 September 2006


The single-input single-output (SISO) orthogonal frequency-division multiplexing (OFDM) systems for wireless local area networks (WLAN) defined by the IEEE 802.11a standard can support data rates up to 54 Mbps. In this paper, we consider deploying two transmit and two receive antennas to increase the data rate up to 108 Mbps. Applying our recent multiple-input multiple-output (MIMO) transceiver designs, that is, the geometric mean decomposition (GMD) and the uniform channel decomposition (UCD) schemes, we propose simple and efficient closed-loop MIMO-OFDM designs for much improved performance, compared to the standard singular value decomposition (SVD) based schemes as well as the open-loop V-BLAST (vertical Bell Labs layered space-time) based counterparts. In the explicit feedback mode, precoder feedback is needed for the proposed schemes. We show that the overhead of feedback can be made very moderate by using a vector quantization method. In the time-division duplex (TDD) mode where the channel reciprocity is exploited, our schemes turn out to be robust against the mismatch between the uplink and downlink channels. The advantages of our schemes are demonstrated via extensive numerical examples.


Singular Value DecompositionWireless Local Area NetworkVector QuantizationFeedback ModeExplicit Feedback


Authors’ Affiliations

Department of Electrical and Computer Engineering, University of Florida, Gainesville, USA
Department of Electrical and Computer Engineering, University of Colorado, Boulder, USA


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© Xiayu Zheng et al. 2006

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.