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| Low Rate CSI Feedback and Capacity Analysis in Multiuser-MIMO-OFDM System |
| Zhang Yi-heng①②; Cui Qi-mei①; Tao Xiao-feng① |
①Key Laboratory of Universal Wireless Communications,
Beijing University of Posts and Telecommunications, Beijing 100876, China; ②Research Institute of Highway (RIOH) Transport Consultants Ltd, Beijing 10088, China |
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Abstract A low rate CSI (Channel State Information) feedback scheme based on linear prediction is proposed for closed-loop multi-user MIMO-OFDM systems. The subcarriers in OFDM system are divided into several sub-bands according to the coherence bandwidth. MS (Mobile Station) predicts CSI of each sub-band, then feedbacks the quantized and coded prediction error to BS (Base Station). BS recovers CSI from feedback information with the same linear predictor, and performs multi-user spatial multiplexing by zero-forcing beamforming with recovered CSI. The downlink capacities are analyzed in theory, where water-filling power allocation method is assumed. Numerical simulations verify that, BS can recover CSI precisely even if the feedback data (real part or imaginary part) is quantized only by one bit. Compared with the 3GPP LTE’s feedback scheme based on codebook, the proposed scheme can suppress CCI better, and achieve much larger capacity. Meanwhile the feedback payload is same as that of 3GPP LTE’s scheme.
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Received: 08 July 2008
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2009, Vol. 31 
