| The increasingly demand of service gives rise to the modern telecommunication network's evolution from traditional voice network to the NGN based on IP packet transmission. The target system of NGN not only facilitates multimedia service and various subsidiary services, but also offers interfaces to the third party, which facilitates new service with a relatively low development and operating cost. However, as NGN is based on IP packet transmission, it is difficult to ensure end to end QoS. This thesis starts by introducing the background of next generation from the perspective of telecommunication network's development. It introduces and analyzes the definition, structure and basic features of NGN. Then it focuses on the implementation of service control and adaptive control of media stream under the NGN system with regard to the service and packet transmission related features of NGN. This thesis illustrates the methods of realizing the NGN function with the SoftSwitch technology based on the service related features of NGN. It firstly proposes the concept and designing thoughts of SoftSwitch, and the call model of SoftSwitch,using the call model of Intelligent Network for reference. Then it suggests two methods for the implementation of service under the NGN system, namely, IN development mode and 3rd party utilizing opening APIs development mode, such as Parlay and JAIN. Finally, from the author's R&D experience concerning alarm service and color ring service, examples are set to illustrate the implementation method of service control under NGN framework. Based on features of the NGN packet transmission, a conclusion is made that terminals should be self-adaptive intelligent to ensure the steady transmission of media stream. RTCP can be used to give feedback to the transmission condition. Several methods concerning terminal's self-adaptive control of media stream transmission according to the RTCP feedback data are therefore proposed. |
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