The Capacity of Downlink Multiuser OFDM with Quality Based CSI Feedback

Jongin KIM  Dongwoo KIM  Sehun KIM  

IEICE TRANSACTIONS on Communications   Vol.E92-B   No.4   pp.1252-1257
Publication Date: 2009/04/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E92.B.1252
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
multiuser OFDM,  capacity,  CSI,  feedback channel,  

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The capacity of multiuser OFDM systems can be maximized by allocating resources (subcarrier and power) to the user with the highest instantaneous channel gain. This assumes complete channel state information (CSI) at the transmitter, which is achieved by every user reporting its CSI for all subcarriers to the transmitter via feedback channel. In practice, due to the limited capacity of the feedback channel, the completeness of CSI may be severely restricted especially with a large number of users transmitting a large amount of feedback information. In order to reduce the amount of feedback information while preserving the maximal capacity, quality based CSI feedback (QCF) is proposed in this letter. The system capacity is derived with QCF and compared with that of full CSI feedback. The results show that QCF successfully reduces the amount of feedback information with little capacity loss.