GPRS

GPRS, or General Packet Radio Service, is a packet-switched data service added to GSM networks to provide mobile data transmission. It enables devices to access IP-based services such as web browsing, email, and multimedia messaging with an always-on connection, unlike traditional circuit-switched data that uses dedicated channels for each session.

In operation, GPRS introduces a packet-switched core network alongside the existing GSM infrastructure. The mobile device establishes a PDP (packet data protocol) context to receive an IP address, and data packets are routed through the Serving GPRS Support Node (SGSN) and Gateway GPRS Support Node (GGSN). The GPRS backbone uses the GPRS Tunneling Protocol (GTP) to carry user data between nodes. On the radio side, transmission rates depend on how many time slots on a GSM carrier are allocated for the session and on coding schemes. GPRS defines four coding schemes (CS-1 through CS-4) that offer different trade-offs between speed and error protection, enabling flexible performance in varying radio conditions.

Data rates in practice are typically in the tens of kilobits per second per user, with higher rates possible when more time slots are allocated and channel conditions are favorable. The technology also supports multiple simultaneous PDP contexts, allowing several IP connections for a given device or user plane session.

History and impact: GPRS was developed by the 3GPP as part of the evolution of GSM networks toward packet-based data services. Standardization occurred in the late 1990s, with commercial deployments beginning in the early 2000s. GPRS laid the groundwork for mobile data on 2G networks and paved the way for subsequent technologies such as Enhanced Data rates for GSM Evolution (EDGE) and later 3G networks. While largely superseded in urban networks by newer generations, GPRS remains a foundational step in the history of mobile data.