Study Of VoIP QoS Based On DiffServ And VBR Coding Technology

A new scheme of VoIP QoS is proposed based on Differentiated Services (DiffServ) network and VoIP terminals using AMR (Adaptive Multi-Rate) technology. In Differentiated Services architecture, the individual flow is mapped to the class of traffic at the edges of the network, and then routers assign appropriate network resources to each class by scheduling and dropping algorithms. Because DiffServ does not micro-manage the resources, a new scheme of VoIP QoS is proposed by adopting AMR on VoIP terminals so that the coding rate of each flow can be adaptively adjusted on real network conditions, and the QoS can also be improved. For evaluating the efficiency of the scheme, many simulation experiments are performed using the most popular NS-2 network simulator. The average packet loss rate, delay and jitter are regarded as the main evaluating parameters. The results of simulation experiments show that this scheme can provide better QoS guarantee than the best-effort scheme (providing best-effort Internet service in networks and adopting G.729 on terminals) and the Differentiated Services scheme (providing Differentiated Services in networks and adopting G.729 on terminals).