Behavior of a Multi-User MIMO System in Time-Varying Environments

Yasutaka OGAWA  Kanako YAMAGUCHI  Huu Phu BUI  Toshihiko NISHIMURA  Takeo OHGANE  

Publication
IEICE TRANSACTIONS on Communications   Vol.E96-B   No.10   pp.2364-2371
Publication Date: 2013/10/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E96.B.2364
Print ISSN: 0916-8516
Type of Manuscript: INVITED PAPER (Special Section on Recent Progress in Antennas and Propagation in Conjunction with Main Topics of ISAP2012)
Category: 
Keyword: 
multi-user MIMO system,  channel state information,  time-varying environment,  channel prediction,  autoregressive (AR) model-based prediction,  

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Summary: 
We evaluated the behavior of a multi-user multiple-input multiple-output (MIMO) system in time-varying channels using measured data. A base station for downlink or broadcast transmission requires downlink channel state information (CSI), which is outdated in time-varying environments and we encounter degraded performance due to interference. One of the countermeasures against time-variant environments is predicting channels with an autoregressive (AR) model-based method. We modified the AR prediction for a time division duplex system. We conducted measurement campaigns in indoor environments to verify the performance of the scheme of channel prediction in an actual environment and measured channel data. We obtained the bit-error rate (BER) using these data. The AR-model-based technique of prediction assuming the Jakes' model was found to reduce BER. Also, the optimum AR-model order was investigated by using the channel data we measured.