What Is a GPRS System?

GPRS is abbreviated as General packet radio service in English, and the Chinese name is General Wireless Packet Service. It is a wireless packet switching technology based on the GSM system, which provides end-to-end, wide-area wireless IP connectivity. Compared with the circuit-switched data transmission method of the original GSM dial-up method, GPRS is a packet-switched technology that has the advantages of "real-time online", "charge-by-amount", "quick login", "high-speed transmission", and "free switching". In layman's terms, GPRS is a high-speed data processing technology. The method is to transmit data to users in the form of "packets". GPRS is a 2.5-generation communication technology that the GSM network has transitioned to the third-generation mobile communication system, which has significant advantages in many aspects ^[1] .

GSM-GPRS completes the packet data function by adding a series of functional entities on the basis of the original GSM network. The newly added functional entities form the GSM-GPRS network. As an independent network entity, the CSM data is bypassed to complete the GPRS service. The original GSM network Then it completes the voice function and minimizes changes to the CSM network. The GPRS network and the GSM original network jointly complete the mobile management function of the mobile station through a series of interface protocols. CPRS has added some new functional entities: serving GPRS support node SCSN, gateway GPRS support node GCSN, point-to-multipoint data service center, etc., and a series of enhancements to the software functions of the original functional entities. GPRS borrows and uses data on a large scale. Communication technology and products, including frame relay, router, access network server, firewall, etc. GPRS was first proposed in 1993, and the first phase of the protocol was introduced in 1997. So far, the GPRS protocol has been continuously updated. SMG # 30 was introduced in early 2000. The anonymous access function is no longer reflected in the new protocol. In addition to the newly introduced protocols, the GPRS protocol has also made a number of modifications to the original protocols ^[2]

General Packet Radio Service Technology (General Packet Raciio Service, GPRS) is a packet-switched data service based on GSM. It is used to supplement circuit-switched services and is an important upgrade to GSM technology. GPRS adds Serving GPRS Suf (portNode, SGSN), gateway GPRS support node (Gateway GPRS Support Node, GGSN) and packet control on the existing GSM (Global System For Mobile C.ommunica-tions) network Unit (Packet Control Unit, PCU), three new logical network entities, communicate with Interne't through the IP protocol. PCU is mainly used to process data services, manage packet segmentation and planning, wireless channels, transmission error detection and automatic retransmission, channel coding scheme, quality control, power control, etc., and are added to the Base Station Controller (BSC) . SGSN is at the same system level as Mobile Service Switching Center (MSC). It is used to track the location of mobile stations, perform mobility management, security functions and access. For mobile stations, SGSN is the service access of GPRS network. point. The GGSN provides an interface between the GPRS network and an external network (such as a 1P network). When there is a data packet on the external network that needs to be transmitted to the mobile station, the data packet first reaches the GGSN, and then the South GGSN forwards it to the SGSN corresponding to the mobile station. When the mobile station wants to send a data packet to the external network, it is also forwarded by the GGSN. Before the GPRS mobile station uses the GPRS service, it must first go through the GPRS attach process. After the attach process is completed, the SGSN establishes the information of the mobile station and performs mobility management on the mobile station to obtain the information of the mobile station as much as possible. If the mobile station wants to access the external data network, it needs to initiate a PDP (Packet Data Proiocol) context activation process. Through this process, the mobile station can establish a logical path to the GGSN so that it can access the external data network. ^[3]

(1) Data transmission speed. GPRS mobile phone is 10 times faster than GSM mobile phone, which meets the ideal needs of users, and can also stably transmit large-capacity high-quality audio and video files ^[4]

GPRS is an application service bearing platform, which provides a transmission channel from a mobile phone (data terminal) to the service platform. The real business is realized by the service development platform, which provides abundant IP-based and mobile services. GPRS can support almost all data application services except interactive multimedia services. GPRS services can be divided into point-to-point services and point-to-multipoint services. At present, point-to-multipoint specifications have not been completed. Internet business. GPRS provides users with convenient and high-speed mobile Internet services, such as Web browsing, E-mail FTP file transfer, Telnet remote login, etc .; mobile office, mobile data access services (providing internet communication with the corporate intranet); WAP services, chat, Mobile QQ, online games, etc .; GPRS short message services; remote operations (online stock trading, mobile banking, etc.); positioning services (GPS positioning information transmission); information services. GPRS can provide users with a variety of information services, such as news, timetables, traffic information account inquiry, stock market quotes, dispatch management, booking, weather forecast, gambling, business advertising, etc. ^[5]

GPRS technology perfectly combines mobile communication technology and data communication technology, especially Internet technology. It is the crystallization of these two technologies, and it is the inevitable result of the integration of GSM network and data communication development. GPRS uses packet switching technology, which allows multiple users to share certain fixed channel resources, and also allows each user to occupy up to 8 time slots. If 8 time slots in the TDMA frame on the air interface are bundled for data transmission, wireless data access of up to 71.2 kb / s can be provided, which can provide users with cost-effective services and flexible pricing policies. GPRS can not only enable carriers to provide a variety of services directly, but also provide convenient access methods for third-party service providers, which facilitates the effective separation of network services and services. In addition, GPRS can significantly improve the wireless resource utilization of the GSM system. While ensuring the quality of voice services, it uses idle wireless channel resources to provide packet data services, and can use flexible service scheduling strategies to greatly improve GSM. Network resource utilization ^[6]

The main application areas of GPRS can be: E-mail email, WWW browsing, WAP business, e-commerce, information query, remote monitoring, etc. ^[7] .

People usually divide mobile communication into three generations. The first generation is an analog wireless network, the second generation is digital communication including GSM, CDMA, etc., and the third generation is a packet-based mobile service called 3G. GPRS is the abbreviation of General Packet Radio System. It is a technology between the second and third generations. It is usually called 2.5G because it is a hybrid and uses TDMA to transmit voice. The data is transmitted in packets ^[8] .

GPRS gprs GPRS communication capability

GPRS is a standard for packet data in the European Telecommunications Association's GSM system. It can provide air interface transmission rates up to 115Kb / s. GPRS enables several mobile users to share one wireless channel at the same time, and one mobile user can also use multiple wireless channels. Users who do not actually send or receive data packets occupy only a small portion of network resources. With GPRS, the user's call set-up time is greatly reduced, and it can almost be "AlwaysOnline". In addition, CPRS allows operators to charge based on the amount of data transmitted rather than the connection time, thereby making the service cost of each user lower. GPRS uses channel bundling and enhanced data rate improvement to achieve high-speed access. The current GPRS design can achieve bundling in one carrier frequency or 8 channels, increasing the transmission rate of each channel to 14. 4Kb / s, so the GPRS method is the largest The rate is 8 × 14.4 = 115. 2Kb / s. The second step in the development of GPRS is to improve the transmission performance by enhancing the data rate, that is, the rate of each channel is increased to 48Kb / s, so the second-generation GPRS design rate is 384Kb / s. To implement GPRS, three new logical network entities need to be introduced into the existing GSM network: the serving GPRS support node (SGSN), the gateway GPRS support node (GGSN), and the packet control unit (PCU). SGSN provides interactive operation between GPRS network and external packet data network. In the base station subsystem, the PCU is responsible for managing packet segmentation and planning, wireless channels, transmission error detection and automatic retransmission, channel coding scheme, quality control, power control, etc. ^[8] .

GPRSWAP gprs GPRS in WAP

WAP is a high-level application, and GPRS is a low-level transmission. The fast transmission capability of GPRS will effectively solve the problem of slow Internet access speed of WAP mobile phones. At present, the highest user access rate that GSM circuit data services can provide is 9.6Kb / s. Only a small amount of text information can be transmitted at this rate, such as Fax, Email, FTP, etc. In addition, due to the high wireless network disconnection rate The connection is very unstable, and users often have to re-dial. This speed can basically meet the requirements for transmitting still images. However, with the rapid development of the Internet, users often want to transmit high-quality video and sound. The emergence of GPRS will provide air interface transmission capabilities of up to I15 Kb / s, which will solve the existing problems of WAP Internet access. In addition, GPRS enables operators to charge based on the amount of data transmitted rather than the connection time, thereby greatly reducing costs. Therefore, it can be said that GPRS is the best bearer platform for WAP and the key to the success of WAP services ^[8] .

GPRS Application prospects of gprs GPRS

From the perspective of the network, GPRS can be used in the area where the PCU is provided in the base station subsystem. Otherwise, GPRS cannot be used, because GPRS is located at a low position on the "branch" in the GSM network, which results in regional restrictions on GPRS coverage. Either just implement GPRS in a certain area. As a mobile user, it is unbearable to use GPRS in some areas, but not in other areas. In other words, the threshold for GPRS implementation is very high. Except for complex terminals, the whole network transformation obviously lacks the necessary business support and suitable reasons. The future of CPRS lies in development. Many manufacturers claim that GPRS can smoothly transition to 3C. In short, one of the 3G implementation solutions is to replace the existing base station subsystem with a 3G base station subsystem, and replace the GPRS The network subsystem was upgraded to a 3G network subsystem ^[8] .