General packet radio service (GPRS) is a packet oriented mobile data
service on the 2G and 3G cellular communication system's global system
for mobile communications (GSM). GPRS was originally standardized by
European Telecommunications Standards Institute (ETSI) in response to
the earlier CDPD and i-mode packetswitched cellular technologies. It is
now maintained by the 3rd Generation Partnership Project (3GPP).
GPRS usage is typically charged based on volume of data transferred,
contrasting with circuit switched data, which is usually billed per minute of connection time. Usage above the bundle cap is either charged per megabyte or disallowed.
GPRS is a best-effort service, implying variable throughput and latency
that depend on the number of other users sharing the service
concurrently, asopposed to circuit switching, where a certain quality of
service (QoS) is guaranteed during the connection. In 2G systems, GPRS provides data rates of 56–114 kbitcond. 2G cellular technology combined with GPRS is sometimes described as 2.5G, that is, a technology between the second (2G) and third (3G) generations ofmobile telephony. It provides moderate speed data transfer, by using
unused time division multiple access (TDMA) channels in, for example, theGSM system. GPRS is integrated into GSM Release 97 and newer releases
GPRS extends the GSM Packet circuit switched data capabilities and makes the following services possible:
SMS messaging and broadcasting
"Always on" internet access
Multimedia messaging service (MMS)
Push to talk over cellular (PoC)
Instant messaging and presence—wireless village
Internet applications for smart devices through wireless application protocol (WAP)
Point-to-point (P2P) service: inter-networking with the Internet (IP)
Point-to-Multipoint (P2M) service: point-to-multipoint multicast and point-to-multipoint group calls
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.
GPRS supports the following protocols:
Internet protocol (IP). In practice, built-in mobile browsers use IPv4 since IPv6 was 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 (IPCP not DHCP) to the mobile equipment.
X.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 PPP, or even over IP, but doing this requires either a network-based router to perform encapsulation or intelligence built into the end-device/terminal; 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 even during handover. The TCP handles any packet loss (e.g. due to a radio noise induced pause)