Comprehensive introduction to Wireless Access Network grouping system problems

At present, China's wireless access network is still developing very rapidly. It may be irrelevant for many people to learn about the interfaces in the grouping system in the wireless access network. After reading this article, you will certainly have a lot of GAINS, I hope this article will teach you more things.

Introduction to the interfaces in the evolved grouping system

Gi Interface
Gi is the interface of the external grouped data network of the wireless access network, and also the display point of the terminal IP address in the external data network. All user and control plane functions are processed based on the terminal IP layer, and terminal mobility performance of all 3GPP categories ends in Gi interface pre-processing.

S1 Interface
The S1 interface between the evolution base station and the mobility management entity/service gateway divides the SAE/LTE evolution system into wireless access networks and core networks. Following the concept of separation of bearer and control, the S1 interface is also divided into user plane and control plane. The user Plane Interface S1-UP connects the evolution base station and the service gateway to transmit user data and the corresponding user plane control frame. The Control Plane Interface S1-CP is connected to the evolution base station and the mobility management entity, mainly to complete the S1 interface Wireless Access Network bearer control, interface special operation maintenance and other functions.

X2 Interface
The evolution base stations connect to each other through the X2 interface to form a so-called mesh network. This is a major change in LTE over the traditional mobile communication network. The reason for this change is that the network structure does not have RNC, the original tree branch structure is flattened, so that the base station is responsible for more wireless resource management, and more direct conversations with adjacent base stations are required to ensure seamless switching of users throughout the network. The X2 interface is also divided into user plane and control plane. This interface is mainly used to support mobile phones in the activation mode and forward group data. It can also be used to manage wireless resources in multiple cells.

S11 Interface
S11 is an interface between the mobility management entity and the Service Gateway, which is based on Gn/GTP-CSGSN-GGSN) while adding additional features such as paging assistance, mobility can work with traditional Gn/GTP-CSGSN-GGSN) interface. S11 is a multi-to-many interface.

S10 Interface
S10 is the control interface between mobility management entities, which is based on Gn/GTP-C (SGSN-SGSN) and also adds additional functionality. S10 is a multi-to-many interface.

S5/S8 Interface
S5/S8 is the interface between the service gateway and the Data Network Gateway. S5 and S8 are basically the same interface. The difference is that S8 is used for roaming between different carriers, while S5 is used inside the network. This interface is applicable to two scenarios: one is based on Gn/GP (SGSN-GGSN), the other is used for IETF-specific proxy Mobile IP to implement mobile control, and the additional mechanism is used to process the quality of service. The motive for the proxy Mobile IP address of S5/S8 mainly comes from WiMAX or CDMA 2000 operators and manufacturers. They are interested in the evolution of wireless networks, 2g or 3G wireless network interconnection, we also hope to re-utilize the specific mechanism of the 3GPP SAE to support the internal movement of WiMAX or CDMA. The S5/S8 interface uses the proxy Mobile IP address or the GPPs, but it is not used on the S1 interface or terminal, and does not affect the behavior or terminal of the wireless network. In non-roaming scenarios, the functions of the Service Gateway and Data Network Gateway may be implemented on one physical node. S5/S8 is a multi-to-many interface. The evolved group core network forms the node function.

Mobility Management Entity
Controls core networks. The concept of a mobility management entity is composed of the control plane of SGSN. The Protocol for control plane termination ends in the mobility management entity, and the mobile context of the Mobility Management Entity Management Terminal, as long as the terminal moves within the pool range of the mobility management entity, the same mobility management entity maintains control over the terminal. The mobile management and session management functions executed by the mobility management entity are as follows: Mobile Phone attachment and separation processes allow mobile phones to be registered and unbound from the Internet. Secure 3A mechanism. The mobility management entity implements authentication, authorization, and audit security functions, which are used to identify users, permit wireless access networks, and track user behavior.

Data Network/Service Gateway
The Data Network/service gateway function is very similar to the current GGSN node. The main extension is to increase the data packet cache to support the evolution of Wireless Access Network paging and non-3GPP interconnection. The Data Network Gateway provides interfaces to connect to the external world. The data network/service gateway can be seen as a node in the user plane, although they also execute some quality of service related signaling.

The control plane functions of Data Network/service gateway are as follows:
The evolved grouping system carries management, and the data network/service gateway triggers the establishment of Bearer Based on the request of policy control function. The mobile anchor is used as the display point of the IP address, and the Data Network Gateway acts as the mobile anchor to hide the user's movement to the fixed connection network. When the mobile phone is attached to the network, an IP address is allocated from the data network gateway, and the gateway is assumed to be the mobile phone's mobile anchor. No matter after the mobile phone is switched to another mobile management entity or service gateway, the IP addresses of the mobile phone are maintained in the original data network gateway, the mobile phone is transparent to the fixed connected network.

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