Basic working principle.
GPRS introduces two new network nodes: GPRS service support node (sg-sn) and gateway support node (GGSN) into the former GSM network based on circuit switching (CSD). SGSN and MSC are at the same level, tracking the storage unit of a single MS to achieve security functions and access control. They are connected to the base station system through frame rebroadcasting. GGSN supports the exchange with external group switching network, and they are connected to SGSN through IP based GPRS backbone network. Figure 1 provides the principle block diagram of GPRS and Internet connection.
The GPRS terminal obtains data from the client system through the interface, and the processed GPRS packet data is sent to the GSM base station. After the packet data is encapsulated by SGSN, the SGSN communicates with the gateway support contact GGSN through the GPRS backbone network. The GGSN processes the packet data and sends it to the destination network, such as Internet or X.25 network.
GPRS is the abbreviation of general wireless packet service. It is a communication technology between the second generation and the third generation. The ultra-thin smart card connector is usually called 2.5g.gprs. It adopts the same frequency band, frequency band width, burst structure, wireless modulation standard, frequency band rule and td-ma frame structure as GSM. Therefore, when building GPRS system on the basis of GSM system, most parts of GSM system do not need to change hardware. ICBC smart card connector only needs to upgrade software. With GPRS, the call construction time of wholesale smart card connector users will be greatly shortened, and they can almost always be online. In addition, GPRS charges not based on the amount of data transmitted by operators, but on the connection time, so the service cost of all users is very low.