On capacity of quality-based channel-state reporting in mobile systems with greedy transmission scheduling

Greedy transmission scheduling achieves great capacity by maximally exploiting independent time-varying channels across different mobile users. The improvement in capacity, however, depends on the degree of completeness of the channel quality information (CQI) fed back from the receiver to the transmitter. To be motivated by an insight that too many CQI feedbacks may rather impair the capacity gain, due to causing congestion in feedback link, this letter proposes a quality-based CQI reporting (QBR) scheme where the CQIs are fed back to the transmitter only for receivers whose signal quality is above a predefined threshold. The capacity is provided in terms of the threshold and feedback-error rate. The results show that QBR achieves outstanding performance when the feedback error is present. In addition, it quickly approaches an unimpaired ideal capacity, as the number of users increases if the error is not assumed