Changes in Mobile core networks

 

Changes in Mobile core networks

The mobile communication system consists of three parts: core network (CN), Wireless Access Network (RAN), and mobile station (UE. The core network is responsible for information exchange, routing, user data management, security, and other information exchange and transmission with other communication systems. With the continuous development of mobile communication systems, mobile core networks have also been evolving. In general, the mobile core network has also gone through three stages of development.

In the first generation of mobile communication systems, the mobile core network is connected to the Public Telephone Exchange Network (PSTN) through the mobile exchange center (MSC). In addition, the mobile exchange center is also responsible for the base station (BS) communication. During the call, the Mobile Station establishes a connection with the base station, connects to the mobile exchange center through the base station, and finally connects to the public telephone network. In fact, the main difference between the mobile core network and the traditional wired telephone exchange network is that the mobile core network introduces the functional entity for recording and managing the location of the mobile station, provides mobile phone communication. Therefore, the first-generation mobile core network can be seen as an extension of the traditional wired telephone exchange network in the mobile wireless environment.

After the emergence of the second generation mobile communication system, the main structure of its core network continues the core network structure of the first generation mobile communication system. In the second-generation mobile core network, the mobile exchange center is still the core component of the entire network, and its working principle is very similar to that of the first-generation mobile core network. However, unlike the first-generation mobile core network, the second-generation mobile core network introduces short message service centers that support point-to-point short message services, this allows the second generation of mobile communication systems to provide services similar to digital paging and broadcast-based public information services.

With the rise of the Internet in the later S, data services were increasingly widely used. The second-generation mobile core network further introduced the universal grouping wireless service technology (GPRS ), this technology breaks through the early second generation of mobile core network and can only provide the way of thinking for circuit switching, it only needs to add corresponding functional entities to the original mobile core network and partially transform the existing base station system to implement group exchange within the core network. Specifically, the GPRS technology introduces two new core network functional entities, namely, GGSN and SGSN.

Significant changes in the 3G mobile core network

Compared with the previous mobile core network, the 3G core network has undergone significant changes. From the standard development process, as shown in table 1, the evolution of the core network corresponding to WCDMA and TD-SCDMA has gone through five stages, we can see that: early 3G core networks included Circuit Switching domain (CS domain) and group switching domain (PS domain ). The CS domain provides users with "circuit-based services" or Related Signaling connection routes. Its basic structure and functions are similar to those of the circuit switching part of the 2G core network. However, by introducing the Softswitch technology, the CS domain of the 3G core network enables the network to carry IP addresses. The PS domain provides users with "grouped data services", which are actually developed based on GPRS. However, with the evolution of the 3G core network, the CS domain gradually stops developing, and the PS domain is transformed into an IMS-centered switching domain. In addition to the original grouped data services, the PS domain also needs to provide the bearer for IMS.

The Next Generation Network concept is also introduced in the evolution of the core network of the 3G system cdma 2000. As shown in table 2, the ipvpp2cdma 2000 core network standard is evolved in four stages. It also shows the evolution trend of full IP and the evolution direction to IMS.

After 3G, research on the next-generation mobile communication system has also been carried out. The 3GPP long-term evolution (LTE) project is an important branch, and its research work on the next generation mobile core network is called System Architecture Evolution (LTE-SAE ). The LTE-SAE adopts a new flat architecture, and the mobility management entity, the Service Gateway is its core component, which realizes the separation of network control and user data control.

Full IP, integration and intelligence

With the continuous integration of mobile communication and the Internet, the traditional mobile core network, which focuses on circuit switching, is accelerating the transition to the entire IP network. This means that the structure of the mobile core network will gradually flatten, this significantly reduces network costs, implements simple and efficient network operation and maintenance, and facilitates rapid deployment of new businesses. Therefore, the main features of the future mobile core network can be summarized as: full IP, integration and intelligence.

First, the evolution of the mobile core network shows that the network tends to be fully IP-oriented. From the perspective of the circuit fields of the existing 3G system, mobile Softswitch is gradually replacing the original circuit switching mode based on time division multiplexing, which means that the IP protocol will be more widely used in the circuit fields of the 3G core network. In the next-generation LTE-SAE structure, all functional entities in the network have fully implemented IP communication. Therefore, it can be judged that the IP protocol will gradually replace the circuit switching method based on time division multiplexing and become the mainstream Exchange Protocol of mobile core network.

Secondly, the development of mobile core networks constantly shows the characteristics of convergence, which includes both the convergence within the network and the convergence between different networks. 2G core network first shows the integration of the circuit switching domain and the group switching domain, which indicates that the two systems adopting different switching modes are beginning to appear in the same core network. In the 3G system, the circuit fields based on Softswitch are also in the same core network as those based on IMS. However, in 2G and 3G systems, the circuit and grouping fields run independently of each other, and there is no close relationship between each functional entity, therefore, the internal convergence of such networks is loose and relatively independent. The core network defined by the LTE-SAE is no longer to distinguish the circuit domain and grouping domain, 2G and 3G core network in the original functional entities in the LTE-SAE has been highly integrated, therefore, the structure of LTE-SAE core network has been quite simplified compared with the original mobile core network. The integration of various functional entities within the network brings about a high degree of integration of user data, which facilitates centralized management of user business data and the integration of user-centered business data, to quickly launch new businesses. In terms of the convergence of different networks, the 3G network first realizes the convergence of networks using different access technologies (such as WLAN and xDSL). In the later core networks of the 3G system, these networks using different access technologies have actually become a Wireless Access Subsystem of the entire 3G system. In the LTE-SAE core network, the fusion between different networks is further enhanced, LTE-SAE core network has adopted different access technology network as a unified Wireless Access Network of the entire system, thus achieving a high degree of integration of access methods, this allows users to use different terminals to receive services through the LTE-SAE core network. Therefore, we can see that the future structure of the mobile core network will be simpler and flat, and the entire mobile network will become a heterogeneous and ubiquitous communication system.

Then, with the evolution of fully-IP-based converged networks, mobile core networks are becoming more intelligent. The mobile core network requires the core network to have the telecom-level IP capability, which means that the network needs to meet the telecom-level requirements in terms of IPQoS assurance, reliability and networking flexibility. On the other hand, the development of mobile core networks in network convergence makes it necessary to face the diversity and uncertainty of network resources and user needs. Therefore, in order to cope with the problems brought about by the above two changes, more intelligent functions must be introduced in network management and control of the mobile core network. For example, the mobile core network needs to quickly detect and fix faults in the network. It can flexibly share resources in the network based on users' business needs and achieve load balancing; adaptive Control of the power consumption of network devices.

To sum up, the mobile core network has entered a new stage, and full IP, integration and intelligence are gradually becoming its main feature. The current mobile core network will be the same in the future development and evolution, and eventually form a heterogeneous converged network centered on user business data.

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