Differentiated Services Model

Based on the comparison of the two kinds of IP QoS provision scheme,DiffServ is chosen to be the one for the Core Network(CN) in UMTS.Here the functions of the SGSN(Serving GPRS support Node) and GGSN(Gateway GPRS support Node) are defined,which are the essential elements in CN.Furthermore,the congestion control and scheduling schemes are the objects of the research,and Random Early Detection and Weighted Fair Queuing are the appropriate combination scheme in the nodes of UMTS CN after cautious comparison.In the framework of the classification system in UMTS,the combination of the Allocation/Retention Priority and the Traffic Handling Priority that is the distinct characteristic of the Interactive Class,divides the Interactive Class into several sub-classes,which could be used to mapped with the variety of AF PHBs(Assured Forwarding Per-Hop Behavior) in DiffServ model,in conjunction with the Streaming Class.At the end of this paper,a model is constructed in the simulation software to evaluate the performance of the proposed QoS management scheme of UMTS CN backbone bearer service.It is concluded that the scheme proposed in this paper is an efficient one for CN bearer service,which could improve the performance of packet handling in delay,jitter and loss ratio.