analysis and design of ieee 802.16 uplink scheduling algorithms and proposing the ira algorithm for rtps qos class
Scheduling algorithms in WiMAX are of great importance due to their effect in delivering a high speed broadband while satisfying the traffic Quality of Service (QoS) constraints. A well designed scheduling algorithm should carefully deal with throughput maximization, delay constraints satisfaction and maintaining fairness among subscribers. This paper focuses on uplink (UL) scheduling effect on the performance of real time Polling Services (rtPS) QoS class performance using OFDM as a physical layer where rtPS is a service class for variable bit rate (VBR) data such as MPEG compressed video. Ensuring QoS constraints for rtPS class is challenging due to critical delay constraints and throughput requirements. The paper proposes an uplink scheduling algorithm called the Instantaneously Replacing Algorithm (IRA). The algorithm mainly schedules connections based on their Signal to Noise Ratio (SNR) but instantaneously replaces high SNR connections with connections that may violate their intended QoS requirements. The proposed algorithm is analyzed in the paper using an NS-2 simulation model. Comparing to another set of UL schedulers, simulation results show that the proposed algorithm enhances QoS Satisfaction in the network as it tends to minimize the delay and at the same time distribute the network resources in a fair manner among Subscriber Stations (SSs) while maintaining a throughput comparable to that achieved using SNR based approaches.
uplink scheduling ira rtps wimax