The introduction of the software exchange in the mobile network is also the first one of the development of steps:
--- TANDEM function
In this case, he is basically the same as the softswitch of the fixed network, the media gateway application mode is basically, mainly solves the IP interchange between mobile network and fixed network. Softswate has not yet mobilized functionality and cannot support business-oriented business.
--- GMSC (GATEWAY MSC)
The status of soft exchange is equivalent to the Gateway MSC, with mobility concepts, and HLR via the MAP / IS41 interface, positioning mobile users, supporting new mobility services.
--- VMSC (VMSC (Visited Or Serving MSC)
The third step is true to provide softswitch in VMSC.
Therefore, soft exchange is the same as the fixed network, which is mainly alternative to the traditional assembly network portion to provide IP phones.
2.3 Ripeness of the protocol
2.3.1 Soft Switching Protocol System
Soft exchange protocol requirements include:
--- H.248 protocol between the relay gateway,
--- SigTran protocol with NO.7 interoperability
--- SIP, H.248, MGCP protocol with IP terminals
--- INAP, CAP, MAP protocol with existing intelligent network
--- H.323 protocol with existing H.323IP telephone network
--- SIP-T / BICC protocol with other soft exchanges
--- Agreement with access to the gateway
--- Open API agreement
For the standards of softswitch, the protocol is the key to network integration. The industry, including equipment manufacturers, business providers, is now working hard for standard development, hoping to introduce advanced services, voice applications into the data network, and can be fused with traditional networks. The current standard work is mainly involved in: interoperability; media control protocols (such as MGCP, H.248), communication between Softswun (such as SIP-T, BICC), protocol and API of the business platform; in line with international telephone connection Standard; safety standard; use soft exchange transfer advanced business and other aspects. The relevant standards mainly include H.323, MGCP, SIP, etc. However, the relevant softswitch standards have to be improved, unified and widely accepted. The primary and main challenges faced by soft exchange are multi-protocols, that is, there are many protocols supported by soft exchange, and these agreements come from different standardized organizations, which brings all aspects of technical research, equipment production and communication operations. A lot of difficulties in coordination. At present, there are many work in China in the standardization of agreements, and some agreements have been standardized and some are being developed.
At present, the relevant agreements that have been developed in China have been developed as shown in the following table:
2.4 Soft exchange network maturity
There are still many problems that need to be studied from the network's perspective.
---- Multiple soft exchange of collaborative work
At present, the experiment of softswitch is basically on the basis of soft exchange. Now some operators have also begun to carry out multiple soft exchange tests, from the perspective of the network, using a single softswitch program only suitable for small operations Commercial, rapid implementation in small networks, but for large telecom operators, we must build a softswitch network throughout the country, regardless of the extensibility to interconnection, and the capacity provided by the business. However, when using more than two softswitch networks, communication between softswitch systems will be involved in the softswitch system, which is not standardized enough, and the agreement can be provided by each manufacturer is different, so there is a different manufacturers. The mating and interoperability of soft exchange is not mature enough.
---- Soft exchange classification problem
If the soft exchange can solve multiple softswitch work, what should I use? Is it possible to use a level or a multi-level, some manufacturers also believe that even when using a plurality of softswitch schemes, the program is only implemented in medium-sized networks. For large telecom operators, because the program is built a flat network, its scalability is equally difficult to meet the needs of telecommunications operators in the country. Therefore, some vendors even propose soft exchanges to be divided into terminals level and coincident. If the end office is provided through the unified business point of the whole network, the efficiency of the business is low due to too complex process interaction and media streaming, which may damage part of the business characteristics and reduce business improvement flexibility. There is also a network system that proposes a multi-level position server in a soft exchange in the network. So softswitch network organization issues are not mature. There are still some problems to be studied. 2.5 Third Party provides business maturity
Since the standardization of open interfaces has not been completed, although some manufacturers can provide some third-party business, they are limited to the equipment of the same manufacturer. The cooperation of different manufacturers equipment and the provision of business is not mature.
3. Currently some problems in China's soft exchange development needs
At present, various operators have begun to test and test SoftSwitch technology. With the gradual improvement of performance and implementation of softswitch equipment, how to fully operate across the telecommunications network, but also solve the following problems:
3.1 address problem
SOFTSwitch device is a node in the package switch network, and must have a unique network identification number (IP address in the IP network). And this identification number is generally limited and cannot be allocated any. With the expansion of softswitch networks, this issue will become more and more prominent as the number of user access is increased. A real-world solution is to enable private identification numbers, but follow the mapping problem of public-private identification number. The identity of the device is the most basic problem in the construction of softswitch network, and is the basis for the routing problem discussed below.
