| In recent years, with the development of IP technology, internet and mobile communications, the traditional voice market keeps shrinking and ARPU of fixed network operators also reduces sharply. Besides, the growing market on personal mobile communication also is threatening the conventional market. Considering the nowadays situation in China, telecommunication companies come to realize that the transformation must be put forward in agendas now."A worker must sharpen his tools to facilitate the work". Network is the basis for all the telecommunication services and operators themselves. According to the development of fixed switching network, the intelligent network, soft switching and IMS are different phases in the development of networks. PSTN is the fundamental phase. Soft-switching is also a step of great importance and IMS is the ultimate Architecture of NGN. These three technologies emerged in turn and will coexist in a long time. So far, several telecommunication companies across the world have been involved in the trial and commercial deployment of soft-switching networks. The telecommunication industry in China also sheds great concern on this technology. All the companies such as China Telecom, China Netcom, China Unicom. China Railcom, China Satcom and China Moible have started the research and deployment of soft-switching.The main policy for the Northern Local Voice Network of China Netcom is that: take full advantage of the present PSTN network and maintain the network framework; meanwhile, optimize the network structure and improve the facilities utilization. At the same time, they should also take into account the future development and facilitate the realization of intelligent networks and prolong the lifetime of PSTN. Under the lead of the group company, the soft-switching technology would be introduced, based on the need of service growing, to realize the smooth evolution of the integrate network.The old 15 voice exchanges, each with 200 thousand lines, of Jilin Netcom is incapable of satisfying the current services and has high cost in running and maintaining, which have greatly impeded the development of the whole network. Hence, a transformation needs to be done. However, the local network had been modified by utilizing the traditional PSTN tandem centers in 2005; thus many problems had also been introduced. First, the lifetime of PSTN should be maintained as long as possible, while the new technology of soft-switching should also be merged as soon as possible. Second, the problem of weak trend SPC should also be solved via transformation and modification.While for the Jilin Netcom, the application of soft-switching is still in the stage of trail, the large scale commercial deployment is very necessary. Under the condition of the use of TDM tandem in the modification of intelligent network, the update of weak trend SPC well prepares the use of soft-switching. Therefore, taking full advantage of this transformation to optimize the voice network deployment and devise a robust network, capable of smooth evolution, becomes an important work.This paper takes the modification of weak trend SPC in XX local network of Jilin Netcom as an example, and proposed the whole strategy of the soft-switching development in the whole province, which is the first step of the set up of the network of the whole province. According to the demands of the network, this paper also discusses the local soft-switching network structure, network models of voice channel networks, singling networks and bearer networks from the engineering prospective.This paper is divided into seven chapters, described as follows:The fist chapter is the introduction. This chapter introduces the situation of reduce in ARPU and revenue of fixed network operators. Also, the chapter points out that the transformation needs to be done as soon as possible. The main policy for the Northern Local Voice Network of China Netcom is that the soft-switching technology should be introduced steadily, based on the need of service growing, to realize the smooth evolution of the integrate network. In this background, the fifteen 200 thousand lines weak trend SPC in XX local network of Jilin Netcom needs to be modified. Since the application of soft-switching of Jilin Province is still in the trail stage, the modification of weak trend SPC provides good opportunities for the introduction of soft-switching.The second chapter analyzes the status of Jilin Netcom XX local network and the needs of modification of weak trend SPC. The local network had been modified by utilizing the traditional PSTN tandem centers in 2005, therefore, and network is optimized and local call detailed list and other intelligent services could be provided. However, there are still fifteen 200 thousand traditional exchanges which face the problems of incompetence and high cost. So these facilities should be updated. Replacing the incompetent facilities with soft-switching equipments can eliminate the hazards in network security, improve the ability of service providing and facilitate the evolution of the whole network, so as to support the marker running well.The third chapter describes the concept and function of soft-switching system and protocols, as well as the configuration of different elements of soft-switching system, in order to provide the theoretical basis for the soft-switching network deployment of Jilin Netcom.The fourth chapter analyzes the status of the Province fixed telephone network. Based on this discussion, the networking scheme for intra-province soft-switching is proposed. By comparing different schemes and considering the situation of the network of Jilin Netcom, the deployment plan in two soft-switching division of the province is designed.The fifth chapter is the most important and difficult part of this paper. According to the demands of the network development incompetent facilities modification, this chapter conducts the design on the structure of soft-switching network for the XX local network. The proposed soft-switching network is divided into four layers, including the edge access layer (TG, AG, SG, IAD), the core switching layer or the transfer layer (backbone network, facilities in Metropolitan Networks), control layer (SoftSwitch), service and application layer (integrated service platform). These layers locate in the end office layer of XX local network and are connected to PSTN telephone network via relay and signaling gateway. The novel soft-switching network elements include a pair of SS, a pair of TG, a pair of SG, a pair of SDC, one service platform and a set of network management system. IP dearer network is also constructed to support the soft-switching network.Next, this paper explains the networking of soft-switching from various aspects, such as the schemes of voices channel network, signaling network, bearer network, intelligent network, IP address allocation and the interconnection between soft-switching and background bearer system.The sixth chapter explains the evolution strategy for the network. Evolution schemes from soft-switching to IMS are proposed from different perspectives. The ultimate goal of network development is the IMS-based NGN network.The seventh chapter is the summary of the whole paper. In this chapter, key points of the work are pointed out and several conclusions are drawn. |
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