Opportunistic scheduling with economized CSI feedback for OFDMA/TDD downlink systems

In this paper we propose an economized-CSI (channel state information) opportunistic scheduling (ECOS) scheme for OFDMA/TDD downlink systems. The ECOS scheme consists of a quality-of-service (QoS) guarantee scheduling (QGS) algorithm and a CSI overhead reduction (COR) algorithm. The QGS algorithm guarantees QoS requirements by adjusting priority value and anticipated rate of users dynamically. In addition, it achieves balance between QoS guarantee and throughput maximization by employing a priority threshold. The COR algorithm performs admissible user selection to economize the amount of CSI overhead. Since all users do not need to feed back CSI every frame, the transmission power used for CSI reporting is economized. Besides, the COR algorithm can reduce the computation complexity of the QGS algorithm because the number of users to be scheduled is reduced. Simulation results show that the proposed ECOS scheme greatly reduces the uplink bandwidth occupancy of CSI feedback. Also, it achieves high system throughput and maintains QoS guarantee at high traffic load.