GPRS access network leads to wireless IP

Source: Internet
Author: User

There are many types of access networks, and various technologies have their own advantages and disadvantages. Many people may not understand the characteristics and applications of the GPRS technology in access networks, after reading this article, you must have gained a lot. I hope this article will teach you more things.

GPRS technology promotes Wireless IP

The introduction of GPRS technology organically connects telecom networks and computer networks to develop towards the future of the all-IP network platform. From the GPRS structure, we can see that the connection between the base station and the SGSN device is generally through Frame Relay connection, and the SGSN and GGSN devices are connected through the IP network. GGSN can be converted from an internal IP address to an external IP address by a vro with the NAT network address translation function. MS can access the internal network of GPRS, or you can name it through the external network access network of APN) access the external PDN/Internet.

In the identification GPRS device, for example, in addition to the IMSI and MSISDN numbers used in GSM, the mobile phone MS identity also needs to be assigned an IP address. The identification of SGSN and GGSN of the Network Element equipment includes both the signaling address and the IP address of the Data GGSN. The IP address is used for communication between GSNSGSN and GGSN, GSN communicates with MSC, HLR, and other entities using the 7th signaling address. There are two important database records in the GPRS system. One is the user mobility management context, which is used to manage the location information of mobile users, and the other is the user's PDP context grouping Data Protocol context ), used to manage data routing information between mobile phone MS, Gateway GGSN, and ISPInternet service provider. When MS accesses the GPRS internal network or the external PDN/Internet network, MS sends an activation PDP context request message to SGSN. MS can contract with the carrier to select the GGSN of the fixed service. Or, according to the selection rules of the APN, The SGSN selects the Service's GGSN, And the SGSN then sends a message to the GGSN to establish the PDP context request. GGSN assigns MS an IP address static or dynamic, public or private. In the process of setting up the PDP context, you must authenticate and demonstrate the user's identity and service quality, after the PDP context is successfully created and activated, both MS, SGSN, and GGSN store the user's PDP context information. With the user's location information and data routing information, MS can access resources of the network. With the advent of the second-generation half-product GPRS, some new concepts will be introduced in the development and deployment of GPRS services.

GPRS system capacity concept

The GPRS system capacity includes the network capacity of GSN and rfrf) capacity. In a GSM system, the system capacity is the number of users supported by the system. The GPRS system uses the group exchange technology, and multiple users share wireless channels. For example, when describing the capacity of the GPRS switching system, in addition to the number of users, it also uses the maximum number of PDP contexts stored, the number of user attachments, and the number of Activated PDP contexts, data throughput, and other indicators. In the description of the GPRS system capacity, we should consider the number of GPRS channels, the amount of data traffic supported, and the number of GPRS users. In short, it is worth exploring how to quantitatively describe the behaviors and traffic models of GPRS users.

GPRS System Performance Index description

The performance of the GPRS system includes PCU, SGSN, GGSN, and billing system. The reliability of these devices is described in terms of equipment failure rate, service interruption and recovery time, throughput and system capacity, such as processing capacity and billing capacity, and interface indicators of the external network.

Transparent access networks and non-transparent access networks of external networks

When a user accesses the Internet, enterprise intranet, or ISP through the GPRS network, the user's identity and service quality must be authenticated and data encrypted, the allocation of Dynamic IP addresses of MS users can be realized by carriers, enterprise networks, or ISPs respectively. Therefore, GPRS users' access networks can be transparently accessed or non-transparently accessed. If the user's IP address is a public IP address allocated by the carrier dynamically or statically ), if the GGSN is not involved in the user's demonstration and authentication process, the user can access the GPRS internal network or the interconnected network transparently through the GGSN. This method is called a transparent method.

The non-transparent mode is used when you access the enterprise network or ISP through the GPRS network. The IP address of user MS is the private IP address allocated by the enterprise network or ISP dynamically or statically). When a user accesses the enterprise network or ISP, GGSN must be authenticated or demonstrated by a private server in the enterprise network or ISP.

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