Enhanced red-based scheduling (ERBS) scheme in WiMAX network

The WiMAX (Worldwide Interoperability for Microwave Access) is a metropolitan area wireless network which provides high speed internet multimedia service and supports a variety of types of QoS (quality of service). Thus, it is important to allocate bandwidth to different class of traffic effectively in this network. The resource must be allocated effectively to guarantee the delay of real-time traffic. An algorithm named Enhance RED-based Scheduling is proposed in this paper to improve the performance of RED-based Scheduling algorithm. In the latter algorithm, the initial DC (deficit counter) is fixed on a constant value DC_max when the length of the queue exceeds the second threshold. With this method, the service flow with heavier load may have a very large delay while the others have a very small one although they have the same class. The QoS requirement of some queues may not be satisfied. Thus, we propose an enhanced algorithm to solve this problem. In this algorithm, the initial DC will depend on the length of queue if one queue exceeds the second threshold. With this modification, traffic with larger load will be allocated with larger initial DC (or bandwidth) in heavy load condition. Therefore, the extreme condition with equally assigned initial DC will be eliminated.