Packet-switched Network Multimedia Transmission Service Quality

In the traditional packet-switched network, such as Internet, normally there is no concept about Quality of Service (QoS). Based on best-effort service, the network cannot support the continuous data transmission of multimedia applications in a real-time fashion. It is an urgent task to have a new control mechanism for the real-time multimedia applications. This paper discusses the QoS problem in the following four aspects: model of control, scheduling, resource management and admission control.First, it sets an adaptive QoS control model and presents the detail of model entities and the negotiation process. The model has two very attractive characteristics. One is the receiver-oriented method in setting up links and reserving resource. The other is the soft state used for synchronization. By using these methods, the model can easily solve the problem caused by system scalability, users' frequently joining and leaving and the heterogeneity of the system.Second, through the analysis of different scheduling methods, the paper puts forward an Improved Virtual Clock (IVC) scheduling algorithm. The IVC algorithm improves the calculation of the system virtual clock. It also uses a two-level queue scheduling mechanism. The simulation result shows that IVC can provide not only satisfied fairness but also good delay performance.Third, in order to obtain the high network resource utilization while meeting flows' QoS requirements, it takes into consideration the tradeoff between high resource utilization and reliable QoS. Based on the IVC static resource allocation, a dynamic allocation method is used. First of all, this method takes care of delay and loss ratio rather than separately considering one aspect of them in current research. Furthermore, it adjusts the resource allocated to flows dynamically and fairly based on current flows' QoS performance and network resource state. Compared with other...