Study On Soft Switch Organization In GSM Network

China GSM mobile communication network has been developing in recent years. Actually, the network has already reached a world-leading level. Facing more and more users, the current GSM network is not enough in either size or technology. With the rapid development of the communication network technology, the demand for data, voice, video and other services is increasing quickly. Providing users with more flexibility, diversified communication services, and personalized services become the business emphasis of the providers. Therefore, Soft-Switch Technology becomes one of the solutions for the next generation communication network.The Soft-Switch Technology updates the traditional idea of the circuit switching, in the narrower sense, especially the equipment of the Soft-Switch. The most developed area is to separate the call-control functions from the median-gateway business. Such technology is compatible with both 2G and 3G networks. To some extent, it is one of the best technologies that could be applied in the mobile communication network so far.This study introduces the structure, the main network entity, the interface signal of the Soft-Switch. This study analyzes deeply the nationwide long-distance network structure and many possible programs applying the Soft-Switch within the province LAN. Next, this study proposes the possible disaster-recovery network programs, considering the characteristics of soft switching equipment and the variety of the network structure. Last, the results regarding the Soft-Switch network are tested using practical applications.1. The Introduction of Soft-Switch Technology1.1The Structure of the Soft-Switch FunctionThe main idea of the Soft-Switch is service/control and transmission/input and separation, the connectivity and communication through standard agreements among various entities. The functional structure of the Soft-Switch technology is as shown in Figure 1.The main functions is as the followings: the call-control function; the service-providing function; the service-switching function; the exchange function; the SIP acting function; the meter function; the network-management function; the function of routing, address, and authentication; the control and management of H.248 terminal, SIP terminal, MGCP terminal; the function (optional) of No. 7 command (e.g., MTP and its application); the control and management of H.323 terminal (optional).1.2The Calculation of the Main InterfaceIn Figure 2, Mc,Nc,Nb are the major new media control interfaces.(1) Mc Interface is the interface between MSC Server and MGW. The agreement of H. 248/MEGACO, SOGTRAN are applied between them. The main functions include the call-control and the media bearing entities, the connection between different models of calls and the media process.(2) Nc Interface is the interface between MSC and MSC servers. The agreement of ISUP, BICC, SIP are applied. The main functions include the calls within the network, the exchange among control agreements. Physical bearing methods can be TDM, ATM, and IP.(3) Nb Interface is the interface between MGW and MGW. The agreement of NbUP/IuUP is applied. The main functions include the calls within the network,user-plane consultation agreement. Physical bearing methods can be TDM, ATM, and IP. The main interfaces of the Soft-Switch networks are illustrated in Figure 2.2.The Model of the Mobil Soft-Switch GroupBased on the different functions of the Soft-Switch equipments, the various Soft-Switch network models can be classified as the following: