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Journal of Electrical and Computer Engineering
Volume 2013 (2013), Article ID 679032, 20 pages
http://dx.doi.org/10.1155/2013/679032
Research Article

Efficient Joint Estimation and Compensation of CFO, Tx/Rx Frequency-Selective I/Q Imbalance, and the MIMO Radio Channel in OFDM Systems

1Huawei Technologies Duesseldorf GmbH, European Research Center (ERC), Riesstraße 25, 80992 Munich, Germany
2Fraunhofer Heinrich Hertz Institute, Einsteinufer 37, 10587 Berlin, Germany
3Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany

Received 23 May 2012; Revised 23 October 2012; Accepted 18 November 2012

Academic Editor: Luc Vandendorpe

Copyright © 2013 Jian Luo et al. 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.

Abstract

MIMO OFDM is a very promising technique for future wireless communication systems. By applying direct conversion architecture, low-cost, low-power, small size, and flexible implementation of MIMO OFDM systems can be realized. However, the performance of direct conversion architecture-based MIMO OFDM systems can be seriously affected by RF impairments incling carrier frequency offset (CFO) and I/Q-imbalance. While OFDM is sensitive to CFO, direct conversion architecture is sensitive to I/Q imbalance. Such RF impairments aggravate as the carrier frequency becomes higher for example, beyond 60 GHz. To achieve the desired high performance of MIMO OFDM, such RF impairments have to be compensated for. In this paper, the joint compensation of CFO, transmitter and receiver frequency-selective I/Q imbalance, and the MIMO radio channel is investigated. Two preamble-based schemes are proposed for impairment parameter estimation. The proposed preambles are constructed both in time and frequency domains and require much less overhead than the state-of-the-art designs. Furthermore, much lower computational complexity is allowed, enabling efficient implementation. The advantages and effectiveness of both proposed schemes are compared and verified by numerical simulations and complexity analysis.