Low Overhead CQI Feedback in Multi-Carrier Systems

Abstract

Channel quality indication (CQI) feedback is crucial for OFDMA systems that explore multi-channel diversity. As CQI has to be updated frequently, when the number of active users gets large, the CQI feedback load may overwhelm the diversity gain. In this paper a threshold cutting-off CQI feedback scheme is investigated. An iterative learning control method is proposed to reach operating CQI thresholds in real systems. A multi-channel contention-based CQI message delivery scheme is designed and analyzed. Extensive simulation has been conducted to test the proposed scheme. It is observed that while the CQI feedback load is low, the system throughput is maintained at a satisfactory level.