General Packet Radio Service (GPRS) is a packet oriented Mobile Data Service available to users of Global System for Mobile Communications (GSM) and IS-136 mobile phones. It provides data rates from 56 up to 114 kbps.
GPRS can be used for services such as Wireless Application Protocol (WAP) access, Short Message Service (SMS), Multimedia Messaging Service (MMS), and for Internet communication services such as email and World Wide Web access. GPRS data transfer is typically charged per megabyte of throughput, while data communication via traditional circuit switching is billed per minute of connection time, independent of whether the user actually is utilizing 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 is 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).
The GPRS is a new service that provides actual packet radio access for mobile Global System for Mobile Communications (GSM) and Time-Division Multiple Access (TDMA) users. The main benefits of GPRS are that it reserves radio resources only when there is data to send and it reduces reliance on traditional circuit-switched network elements. The increased functionality of GPRS will decrease the incremental cost to provide data services, an occurrence that will, in turn, increase the penetration of data services among consumer and business users.
In addition, GPRS will allow improved quality of data services as measured in terms of reliability, response time, and features supported. The unique applications that will be developed with GPRS will appeal to a broad base of mobile subscribers and allow operators to differentiate their services. These new services will increase capacity requirements on the radio and base-station subsystem resources. One method GPRS uses to alleviate the capacity impacts is sharing the same radio resource among all mobile stations in a cell, providing effective use of the scarce resources. In addition, new core network elements will be deployed to support the high burst ness of data services more efficiently.
The General Packet Radio Service (GPRS) is a new non voice value added service that allows information to be sent and received across a mobile telephone network. It supplements today s Circuit Switched Data and Short Message Service. GPRS is NOT related to GPS (the Global Positioning System), a similar acronym that is often used in mobile contexts.
In addition to providing new services for today s mobile user, GPRS is important as a migration step toward third-generation (3G) networks. GPRS will allow network operators to implement a IP-based core architecture for data
WAP is just a gateway used to access Internet via mobilephone and vice-versa. Usually, GPRS data are billed per kilobyte of information transceived, while circuit-switched data connections are billed per second. The latter is inefficient because even when no data are being transferred, the bandwidth is unavailable to other potential users.
The multiple access methods used in GSM with GPRS are based on frequency division duplexTDMA. During a session, a user is assigned to one pair of up-link and down-link frequency channels. This is combined with time domain statistical multiplexing, i.e. packet modefirst-come first-served packet scheduling, while the up-link uses a scheme very similar to reservation ALOHA. This means that slotted Aloha (S-ALOHA) is used for reservation inquiries during a contention phase, and then the actual data is transferred using dynamic TDMA with first-come first-served scheduling.
GPRS originally supported (in theory) Internet Protocol (IP), Point-to-Point Protocol (PPP) and X.25 connections. The last has been typically used for applications like wireless payment terminals, although it has been removed from the standard. X.25 can still be supported over PPP, or even over IP, but doing this requires either a router to perform encapsulation or intelligence built in to the end-device/terminal e.g. UE(User Equipment). In practice, when the mobile built-in browser is used, IPv4 is being utilized. In this mode PPP is often not supported by the mobile phone operator, while IPv6 is not yet popular. But if the mobile is used as a modem to the connected computer, PPP is used to tunnel IP to the phone. This allows DHCP to assign an IP Address and then the use of IPv4 since IP addresses used by mobile equipment tend to be dynamic.
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 GSM service (voice, SMS), but using only one or the other at a given time. During GSM service (voice call or SMS), GPRS service is suspended, and then resumed automatically after the GSM service (voice call or SMS) has concluded. Most GPRS mobile devices are Class B.
Class C
Are connected to either GPRS service or GSM service (voice, SMS). Must be switched manually between one or the other service.
A true Class A device may be required to transmit on two different frequencies at the same time, and thus will need two radios. To get around this expensive requirement, a GPRS mobile may implement the dual transfer mode (DTM) feature. A DTM-capable mobile may use simultaneous voice and packet data, with the network coordinating to ensure that it is not required to transmit on two different frequencies at the same time. Such mobiles are considered pseudo-Class A, sometimes referred to as "simple class A". Some networks are expected to support DTM in 2007.
GPRS is new technology which speed is a direct function of the number of TDMA time slots assigned, which is the lesser of (a) what the particular cell supports and (b) the maximum capability of the mobile device expressed as a GPRS Multislot Class
