Uplink Downlink Limited Round Robin Scheduling Algorithms

Several polling algorithms have been proposed to overcome the slot wastage problem due to the exchange of POLL or NULL packets in the case of no data to transmit. However, most of these algorithms suffer from achieving the fairness among all slaves. This paper proposes two scheduling algorithms, Uplink Downlink Limited Round Robin (LRR) with fixed cycle time and Uplink Downlink LRR with adaptive cycle time. They utilize the status of the uplink queues in addition to the downlink queues to schedule the slots effectively. The proposed algorithms combine the simplicity and fairness of the LRR algorithm with the efficiency of the queue state dependent packet algorithms. Simulation results show that the proposed scheduling algorithms achieve higher utilization, lower delay and reasonable fairness among the slaves compared to the existed LRR algorithm. These results are proved practically. Experimental results confirm that, the proposed algorithms achieve more than 14% improvement in the utilization compared to the LRR algorithm in asymmetric traffic conditions.