Step-by-Step integration of fixed and mobile networks

With the approaching of 3G, mobile network and fixed network introduce the design idea of softswitch while interpreting the transformation from circuit switching to SoftSwitch, it also represents an important trend-mobile network and fixed network convergence.
With the emergence of new communication methods, methods, and services, the communication Network is evolving to a more open and flexible Next Generation Network (NGN. Based on grouping technology, the next generation network can provide a comprehensive and open Network System for voice, data, multimedia, and other services at the same time, A group, open, and layered network system is a distinctive feature of the Next Generation Network. As the core technology of the Next Generation Network, Softswitch provides Call Control and Connection Control functions for businesses with real-time requirements for the next generation network, and is the core of its call and control. The main feature of Softswitch is that service provision and call control are separated; Call Control and bearer connection are separated; open interfaces allow third parties to provide services.
As the core of the Next Generation Network, Softswitch technology combines the reliability of traditional telephone networks with the flexibility and effectiveness of IP technology, and has become a hot topic in the field of communication. As 3G approaches, mobile networks and fixed networks introduce the design concept of softswitch, and the evolution of circuit switching to Softswitch occurs. An important trend in the evolution process is the convergence of mobile networks and fixed networks.
Mobile Network and fixed network Softswitch Technology
The convergence of mobile networks and fixed networks has become a trend in the future development of communication networks. To achieve network convergence, the core and key content is the convergence of SoftSwitch. Therefore, both the mobile network and the fixed network have introduced the concept of softswitch, laying the technical foundation for the integration of the two networks.
1. Softswitch technology in fixed networks
The soft switch technology is introduced in the fixed network, and services in the traditional circuit switching field are transplanted to the group bearer network for implementation, and a new full IP-based multimedia service system is established. In the initial stage, the Softswitch technology of fixed network is mainly reflected in the transfer of traditional telecom services from dedicated TDM to multi-service transmission networks hosted by IP/ATM, with the help of the Access Gateway, the network layer service transmission is segmented, and the original circuit switching network equipment is divided into physically independent control plane Softswitch devices and bearer Plane Media gateways, implement separation of control and bearer. After that, the softswitch of the fixed network will realize the real IP service characteristics. users access the softswitch network through the SIP/H.264 grouping terminal, the network architecture and service provision method are based on the full IP bearer network.
2. Softswitch technology in Mobile Networks
The third-Generation mobile communication system, WCDMA, developed by 3rd Generation Partnership Project, introduced the concept of softswitch in the core network from the R4 version to separate control and bearer, the original MSC is divided into MSC Server (MSC Server) and media Gateway (MGMedia Gateway ). MSC Server implements call control and mobility management, while MG processes media streams. Call Control between mobile Softswitch mainly uses BICC protocol. In the WCDMA R5 stage, the core network introduces the IP Multimedia Subsystem IMS): In view of the Next Generation Network's principle of separation of bearer, control and business, IMS fully implements the hierarchy of its bearer, session control, and application services. The core feature of IMS is the adoption of the SIP protocol and its independence from access, and the establishment of a Softswitch platform for control of call/session. The proposal of IMS makes the mobile core network evolve along the full IP Network Based on SoftSwitch and IP technology, which also conforms to the development trend of the Next Generation Network.
3. inevitability of network convergence
The development of mobile core network and fixed exchange network is based on the evolution of Softswitch technology. In the future, the network will also be based on SoftSwitch and carried by the grouping network, A business platform separated from the network provides a flexible network for a wide range of businesses. It is precisely the application and development of softswitch in the mobile network and the fixed network that makes network convergence possible. Network convergence allows operators to use wired and wireless access networks to share their core infrastructure networks, greatly reducing their investment costs in network construction. The integrated network combines mobile businesses with fixed application business platforms to share business and media resources, facilitating operators to provide users with richer services with higher service quality. At the same time, the combination of the mobile network and the fixed network can achieve real anytime, anywhere communication, and more options and greater flexibility in communication means and methods.
Network convergence development ideas
Although the integration of mobile and fixed networks represents the development direction of the next generation network, the development of mobile and fixed networks is still independent and has their own evolution methods, to fully integrate the two networks is a long-term and gradual development process.
The architecture of network convergence should first adhere to the principles of network layering and functional separation: separation of the application layer and control layer, so that the business and the user's physical location are unrelated; isolation of the control layer and transmission layer, the call/session control is independent of the bearer control, and the same control capability is provided based on different bearer. the transport layer and the access layer are completely separated, this allows all terminals and access methods to share the same bearer network, making full use of network resources and reducing network complexity.
The system architecture of network convergence can adopt an IMS-based system architecture. Compared with fixed Softswitch, IMS has a more rigorous structure and richer functions. It provides basic mobility management functions through feature entity segmentation, it provides an architecture for communication between mobile Circuit Switching domains, fixed Softswitch networks, and IMS core domains, and promotes the separation of control and data layers by setting an independent database that stores user attributes. Network convergence adopts an IMS-based network convergence solution, which aims to make IMS a Universal Platform Based on SIP sessions. It also supports fixed and mobile access methods to achieve mobile network and fixed network convergence.
Based on various factors, the development of network convergence is as follows:
1) First, the existing mobile network and the fixed network can adopt the Softswitch technology and the softswitch-based IMS technology to evolve to the next-generation mobile network and the next-generation fixed network, and the evolution can adopt the overlapping network strategy or replacement strategy.
2) at the initial stage of network convergence, a network architecture with IMS as the core, mobile network, fixed network, and other networks interconnected with the IMS domain can coexist. Mobile Networks and fixed networks are first integrated at the business layer to provide integrated application services. In this case, two ways can be used to provide services: one is to build a unified business platform, and each network has an interface with it, so that the platform can provide services for multiple networks at the same time; method 2: for common services, each network is still provided in the previous way. For a wide range of broadband data and multimedia services, you can set user attribute identifiers to route to the IMS domain, provided by IMS.
3) with the continuous development and improvement of network technology, the mobile network and fixed network are integrated at the control layer and transmission layer to form a unified core network. At the same time, it achieves ubiquitous and consistent terminal access. At this time, the network will provide the network with IMS as the main session control service, and provide various terminal access methods such as broadband, narrowband, mobile, and fixed, provides user and business mobility and open business capabilities. The integrated network architecture will truly become a unified and Open Network System Based on all IP addresses.
Mobile Network and fixed network integration solution
In the next generation network system, the biggest difference between a mobile network and a fixed network is the difference in the access layer. Because of the different access methods, there is a big difference between the mobile network and the fixed network. Mobile users have the characteristics of roaming. The core control layer of the mobile network-mobile Softswitch, compared with the fixed Softswitch, not only must process call control, it also provides mobile network-specific functions such as location management, database management, and switch control. However, mobile SoftSwitch and fixed Softswitch are essentially the same, and they are the embodiment of the idea of separation of business/control and transmission/access. Therefore, from the technical perspective, the integration of the mobile network and the fixed network can be achieved.
The convergence of mobile networks and fixed networks forms an intersection. This intersection should run through all layers of softswitch in the two networks, such as the service layer, control layer, transmission layer, and access layer, user data management, billing, and customer service should also be included. The functional entities contained in the dataset belong to the mobile Softswitch Network and the fixed Softswitch Network. Integrated solutions should not affect the operation and development of existing networks, reduce the cost of new services, and provide more reliable service quality.
1. Integration of Transmission Layer
The integration of the mobile network and the fixed network at the transmission layer is the prerequisite and basis for the full integration of the control layer and service layer. For the transport layer, the network requirements of the mobile network and the fixed network are completely the same. Both use the IP backbone bearer network, and the network can share a group bearer network. The IP bearer network based on the IP protocol not only conforms to the development trend of the Next Generation Network, but also provides unified security policies and methods for integrated networks to plan IP addresses, establish Qos architecture.
Whether it is the mobile core network based on Softswitch or the fixed network softswitch system, the essence is to use different gateways to connect the media and signaling to the IP bearer network, under the control of the softswitch server, completes signaling processing and media interaction. In this way, the difference between mobile and fixed Softswitch systems is only the difference between signaling and media conversion, so the fusion at the transport layer is completely feasible and natural.
2. Integration of control layer
The integration of the mobile network and the fixed network based on the IP transport layer makes it possible to integrate the upper control layer. Mobile and fixed Softswitch are essentially the same. The functions of the control layer are mainly completed by the softswitch server, while the MSC server in the mobile network is integrated with the call server in the fixed network, it is the core content of the two networks. Only by integrating Softswitch servers can the mobile network and the fixed network be truly integrated.
In order to support user mobility, the MSC Softswitch server in the mobile network must have the location locating function and support switching and roaming functions, which is different from the call server in the fixed network. However, the softswitch server located in the mobile connection department does not differ much from the fixed network. You can use the unified Softswitch control entity to achieve convergence. Therefore, in actual integration, there are two phases:
The first phase is to use a collection network to achieve integration in the collection of long-distance bureaus. The local mobile network is independent of the local fixed network and is connected to the network through the BICC or SIP protocol.
The second stage is the integration of local authorities. Because both the mobile and fixed networks use the control and media separation idea, the softswitch servers in the two networks can adopt the unified Softswitch control module, as long as mobile SoftSwitch and fixed Softswitch access devices, such as MG, SG, and IAD, are provided in their respective local bureaus (lower layers) and related protocol functions, such as RANAP, DTAP, Megaco, and MGCP. In this way, the softswitch servers in the mobile network and the fixed network can be combined into one. For mobile network and fixed network access devices, they "see" the same Softswitch server.
3. Integration of the access layer
Because the access layers of mobile and fixed networks support different access methods, and the functional requirements of mobile and fixed media gateways vary greatly, and the encoding methods of mobile and fixed networks are different, therefore, the interconnection between the two networks must be converted at the Access Gateway. At the same time, because the integration of the access layer is mainly achieved through integrated access to the media gateway, the integration of the Media Gateway can be divided into two steps: Step 1, the two networks must have the same interface for accessing the media gateway and support a common encoding type. In this way, the media gateway can be directly interconnected to facilitate access to the same transmission network. Step 2, to achieve the convergence of media gateways.
In this way, the media gateway can be connected to both wireless devices and fixed Softswitch devices. At the same time, the media gateway also needs to have the encoding conversion capability.
4. Business-layer Integration
Business convergence is the ultimate goal of mobile and fixed network convergence. The development of a fixed network requires that network operations and business operations be separated to form a business provider independent of the network provider, thus forming a situation where all participants provide and use services and share benefits. The key technology to achieve this goal is to adopt an open and standard application programming interface-ParlayAPI interface. At the same time, the 3GPP organization also proposed a 3G business provision OSA structure based on ParlayAPI. OSA provides an open, standard, and unified network application programming interface to service providers, provides personalized services for mobile users. Therefore, both the fixed Softswitch Network and the mobile 3G network support ParlayAPI, which provides a good foundation for establishing a unified business platform.
The mobile network and the fixed network have the same business goals. The two use the ParlayAPI interface to abstract the resources in their respective networks into APIs and open them to third-party service providers; A business logic developed by a third-party service provider can be used to serve two networks, which enables the integration of the two at the application layer. For the whole service provider, it can give full play to its own advantages, in the business-driven development trend, we can improve core competitiveness and find favorable growth points.
5. User Data Management
The integration of the mobile network and the fixed network should also include the unified management and maintenance of user data. The user data of the mobile softswitch system includes user data/authentication data, business data, and location information. Fixed users may not need location information, but the mobility of fixed users is one of the important trends in the development of fixed network services, such as the mobility of smart terminals such as SIP. Whether it is a mobile user based on a mobile network or a smart terminal based on a fixed network, to achieve its mobility, the device authentication, user authentication, and user location information must be updated, and business data updates.
In essence, mobile and fixed networks provide the same support for user mobility. They only differ in the entity and protocol. Therefore, the mobile network and the fixed network based on Softswitch can be fully integrated at the user data layer. The user data to be managed can be stored and managed in a unified manner. Standard interfaces are provided externally. For Softswitch devices in the current network, because the amount of information interaction is much larger than that of the external network, you can choose internal interfaces with relatively high efficiency and low costs, this is the same as the idea that VLR is usually built into MSC in mobile networks. Based on the above analysis, the user's database is completely unified in the integrated Softswitch Network. User data also includes business trigger data. The fusion of the integrated Softswitch Network at the user data layer also lays the foundation for the integration of business networks.