Precoding Scheme Robust to Imperfect CSI in Downlink Multiuser MIMO-OFDM System

Linchen CHANG
Kazuhiko FUKAWA
Hiroshi SUZUKI
Satoshi SUYAMA

IEICE TRANSACTIONS on Communications   Vol.E94-B    No.12    pp.3515-3524
Publication Date: 2011/12/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E94.B.3515
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
multiuser MIMO,  MIMO-OFDM,  precoding,  imperfect channel state information,  steepest descent algorithm,  

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This paper proposes a precoding scheme for downlink multiuser MIMO-OFDM systems. The proposed precoding employs the minimum average bit error rate (MABER) criterion, and obtains precoding matrices by the steepest descent algorithm in order to minimize average BER of mobile stations. As the cost function of the proposed scheme, an upper bound of the average BER is derived from the pairwise error probability (PEP) and is averaged with respect to channel state information (CSI) errors. Thus, the MABER scheme is robust against imperfect CSI. Computer simulations under a frequency-selective fading condition demonstrate that the proposed precoder is more robust against the CSI errors than both the zero-forcing (ZF) precoder and a robust sum mean square error (SMSE) precoder, and that it is superior in BER to the conventional schemes.