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【正文】 acket oriented mobile data service available to users of the 2G cellular munication systems global system for mobile munications (GSM), as well as in the 3G systems. In 2G systems, GPRS provides data rates of 56114 kbit/s. GPRS data transfer is typically charged per megabyte of traffic transferred, while data munication 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 besteffort packet switched service, as opposed to circuit switching, where a certain quality of service (QoS) is guaranteed during the connection for nonmobile users. 2G cellular systems bined with GPRS are often described as , 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 works are being converted to use the GSM standard, so that GSM is the only kind of work where GPRS is in use. GPRS is integrated into GSM Release 97 and newer releases. It was originally standardized by European Telemunications Standards Institute (ETSI), but now by the 3rd Generation Partnership Project (3GPP) . GPRS was developed as a GSM response to the earlier CDPD and imode packet switched cellular technologies. Technical overview Services offered GPRS extends the GSM circuit switched data capabilities and makes the following services possible: Always on inter access Multimedia messaging service (MMS) Push to talk over cellular (PoC/PTT) Instant messaging and presence—wireless village Inter applications for smart devices through wireless application protocol (WAP) Pointtopoint (P2P) service: interworking with the Inter (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 supported GPRS supports the following protocols: inter protocol (IP). In practice, mobile builtin browsers use IPv4 since IPv6 is not yet popular. pointtopoint 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 pu
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