CQI Feedback Overhead Reduction for Multicarrier MIMO Transmission

Erlin ZENG  Shihua ZHU  Ming XU  

IEICE TRANSACTIONS on Communications   Vol.E91-B   No.7   pp.2310-2320
Publication Date: 2008/07/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e91-b.7.2310
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
MIMO,  OFDM,  channel quality indication,  feedback reduction,  DCT,  

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For wideband MIMO-OFDM systems, scheduling and link adaptation are key techniques to improve the throughput performance. However, in systems without reciprocity between the uplink and the downlink channels, these techniques require a high feedback overhead of the channel quality indication (CQI) information. In this paper, we propose a novel CQI feedback reduction method, which is based on the conventional compression techniques exploiting the discrete cosine transformation (DCT). The basic idea is to adaptively permute the CQI sequences of different MIMO streams according to one of the possible patterns before the DCT compression so that the amount of feedback bits is minimized. The possible patterns used are carefully designed according to our analysis of the two types of correlations (the inter-stream correlation and the inter-subband correlation) that exist in MIMO-OFDM transmission, as well as their impact on the compression efficiency. Simulation results verify that the proposed method can effectively reduce the CQI feedback overhead under varying channel conditions.