QoS Aware Packet Scheduling for All-IP Networks

Running time sensitive multimedia services such as Voice-over-IP (VoIP) and Video-on-Demand (VoD) on All-IP networks may have lower quality than that on the traditional circuit-switched networks. Packets may suffer from long delay time, large jitter and high packet loss rate. When a packet arrives its destination late, there is no way to correct the problem. Thus, it will be beneficial if routers could forward packets according to their timeliness and QoS class giving important late packets proper precedence. This paper proposes a charge-based optimization model for packet scheduling aiming to maximize overall satisfaction as well as to develop a simple and effective scheduling policy based on this concept for the environments where packets have predefined hop-by-hop time schedules. To forward a packet, a router first assigns it an adequate profit function based on its timeliness and QoS class as well as the loading status in its succeeding routers and then inserts the packet into an appropriate position in the output queues. The performance of this approach is evaluated by simulation using NS-2 network simulator. Simulation results show that, under heavy load, our approach can outperform easily the Simulated Priority Queue that differentiates QoS class only