通用分组无线服务技术.doc

无锡职业技术学院毕业设计说明书（英文翻译）General Packet Radio ServiceGeneral packet radio service (GPRS) is a packet oriented mobile data service available to users of the 2G cellular communication systems global system for mobile communications (GSM), as well as in the 3G systems. In 2G systems, GPRS provides data rates of 56-114 Kbit/s.GPRS data transfer is typically charged per megabyte of traffic transferred, while data communication via traditional circuit switching is billed per minute of connection time, independent of whether the user actually is using the capacity or is in an idle state. GPRS is a best-effort packet switched service, as opposed to circuit switching, where a certain quality of service (QoS) is guaranteed during the connection for non-mobile users.2G cellular systems combined with GPRS are often described as 2.5G, that is, a technology between the second (2G) and third (3G) generations of mobile telephony. It provides moderate speed data transfer, by using unused time division multiple access (TDMA) channels in, for example, the GSM system. Originally there was some thought to extend GPRS to cover other standards, but instead those networks are being converted to use the GSM standard, so that GSM is the only kind of network where GPRS is in use. GPRS is integrated into GSM Release 97 and newer releases. It was originally standardized by European Telecommunications Standards Institute (ETSI), but now by the 3rd Generation Partnership Project (3GPP).GPRS was developed as a GSM response to the earlier CDPD and i-mode packet switched cellular technologies.Technical overviewServices offeredGPRS extends the GSM circuit switched data capabilities and makes the following services possible:"Always on" internet accessMultimedia messaging service (MMS)Push to talk over cellular (POC/PTT)Instant messaging and presence一wireless villageInternet applications for smart devices through wireless application protocol (WAP) Point-to-point (P2P) service: inter-networking with the Internet (IP)If SMS over GPRS is used, an SMS transmission speed of about 30 SMS messages per minute may be achieved. This is much faster than using the ordinary SMS over GSM, whose SMS transmission speed is about 6 to 10 SMS messages per minute.Protocols supportedGPRS supports the following protocols:internet protocol (IP). In practice, mobile built-in browsers use IPv4 since IPv6 is not yet popular.point-to-point protocol (PPP). In this mode PPP is often not supported by the mobile phone operator but if the mobile is used as a modem to the connected computer, PPP is used to tunnel IP to the phone. This allows an IP address to be assigned dynamically to the mobile equipment.GPRS can provide up to 115 kbit/s transmission rate (high of 171.2 kbit/s, not including FEC). This means that in a few years, through the portable computer, GPRS users can and ISDN users to browse the Internet as fast, but also make some of the transmission rate sensitive mobile multimedia applications become possible.access time is short packet switching access time shortened to less than 1 GPRS is a kind of new GSM data business, and it can give mobile users with wireless packet data by the contribution of the travel. GPRS is mainly in the mobile user and distal data network, such as support TCP/IR x.25 and other network) provide a link between, thus to provide mobile users high-speed wireless IP and wireless x.25 businessGSN have two types: one is SGSN (Serving GSN, service GSN), another for GGSN (GatewayGSN, the gateway GSN), SGSN is main function is to record the current position of the mobile information, and in the mobile and GGSN finish of mobile group data between the sending and receiving. GGSN basically is an gateway function, it can and DuoZhong different data network, such as ISDN, PSPDN and LAN, etc. Some literature, the GGSN called GPRS router. GGSN can put the GSM network packets of GPRS group for protocol conversion, which can take the group sent packets to a remote TCP/IP or x.25 networkX.25 connections. This is typically used for applications like wireless payment terminals, although it has been removed from the standard. X.25 can still be supported over PPR or even over IR but doing this requires either a network based router to perform encapsulation or intelligence built in to the end・device/terniinal; e.g., user equipment (UE).When TCP/IP is used, each phone can have one or more IP addresses allocated. GPRS will store and forward the IP packets to the phone during cell handover (when you move from one cell to another). TCP handles any packet loss (e.g. due to a radio noise induced pause) resulting in a temporary throttling in transmission speed.HardwareDevices supporting GPRS are divided into three classes:Class A:Can be connected to GPRS service and GSM service (voice, SMS), using both at the same time. Such devices are known to be available today.Class B :Can be connected to GPRS service and GS。