A downlink scheduling scheme with link layer channel estimation in wireless networks

It is a common understanding that scheduling algorithms of multi-access wireless networks can exploit the channel state information (CSI) to improve the system performance. Typical channel aware scheduling algorithms usually require the instantaneous CSI estimated at the physical layer. However, such information may not be available to the schedulers of some wireless systems. Instead, the long term CSI obtained from the error control scheme of the link layer can be used for the same purpose. In this paper, we propose a metric to denote the long term CSI, and develop a novel method to extract the metric from the link layer. Based on the proposed metric, we implement two channel-aware downlink scheduling algorithms. The first algorithm jointly considers the channel quality and queue states for throughput optimization. The second algorithm takes long term throughput fairness of terminals into account. The proposed algorithms are independent of specific physical layer implementations, and can be employed in all wireless systems that enable the error control scheme in the link layer.