Study On Related Technologies With VoIP

With the development of computer science and network technology, information network based on the multimedia communication has become the focus all over the world. The surprised success of the Internet has made the IP technology become one of the key technologies in the future network. In the process of the network evolution, IP based packet switch and mobilization based wireless communication have been the mainstream. IP based network technology has entered into the telecommunication area. IP phone's success is a cheering omen of the emergency of the next generation network based on IP. IP phone is one of the multimedia services provided by VoIP(Voice over IP). In this paper, a study of several important problems related with VoIP is conducted.On the basis of the background introduction and a brief survey of existing techniques, the first deep study concentrates on the current IP signaling technique and a new idea of constructing uniform semantic independent platform on which signaling control and network management information transparently transmitted is pointed out. A multimedia network with active elements can also be constructed on the platform. Based on this idea, a new signaling system SNSP(Simple Network Signaling System) which conforms to the soft-switch architecture is designed, its construction and function module is analyzed. The Wireless Access Central Office System(WACOS) based on SNSP is developed and has passed the related test and the test result shows that SNSP can be efficiently used for the heterogeneous network connection without semantic loss of signaling information mapping. SNSP behaves well in the integration of call control and network management and decreases the network maintenance cost. SNSP satisfies the requirements of soft-switch architecture and facilitates the network element activity.The second deep study is on the IP QoS problem which is the key issue in the process of constructing the IP based integrated service bearing network. The main factor which influences the IP QoS is analyzed first, then a new idea which make the IP QoS layered is pointed out. For the real time service such as voice, the IP QoS layered model is constructed and the concept "customer satisfaction (S)" is introduced to evaluate the service quality directly feeling bycustomer. Following the idea of risk analysis in the reliability engineering, some network layer QoS parameters related with S are given. As an example, the relation between the network layer risk parameters and the network resource is studied for voice service, and the simulation shows the rationality of the theory analysis.After the constructing the risk based analysis model on the IP QoS, a new QoS routing strategy based on the risk parameters is pointed out. A theory proof shows that the QoS routing problem based on the risk parameters is a NP complete problem under some conditions. After a deep study on existing QoS routing algorithms and some heuristic algorithms are put forward, also their computing complexities are analyzed.Meanwhile, a survey of possible schemes on the IP phone based on the current network conditions is given. The separation of gateway function and some related schemes for the connection between Internet and PSTN are introduced with some possible service quality control methods, especially on the application about the use of the effective bandwidth concept. Based on this introduction, the possibility of applying S as the parameter in the call admission control is analyzed and the related computing method is discussed.At the end of this paper, the summarization of the research is given and some future research directions are discussed.