General Packet Radio Service
GSM Glossary
GSM — General Packet Radio Service
Information on General Packet Radio Service
The General Packet Radio Service is a 2.5G
add-on to GSM and other second generation cellular communications systems
that provides an always-on packet data capability.
The General Packet Radio Service (general
packet radio service) is an ETSI standard that allows a
GSM or D-AMPS network to support transfer of internet protocol
(IP) packet data at air-interface transfer rates of up to
115 Kbps. This maximum data rate is typically shared among
a number of mobile terminals; it would be rare for
the whole capacity to be available to a single mobile
terminal for a long period of time. General Packet Radio Service uses
the same modulation scheme (GMSK) as other GSM services. The
General Packet Radio Service is allocated one or more
time division multiple acces (TDMA) slots in the same way
that these slots are allocated to circuit-switched traffic. The slots
allocated to the General Packet Radio Service are
then shared by General Packet Radio Service users. The capacity allocated to
the General Packet Radio Service can be changed
dynamically, allowing General Packet Radio Service to use capacity not currently allocated
to circuit-switched traffic. Packet data is transmitted in packet data
channels (PDCH). Each packet data channel (PDCH) occupies a single
slot in a GSM frame, in the same way as
a traffic channel. Packet data is routed to individual terminals.
General Packet Radio Service defines three types of mobile station. Class A stations
support simultaneous circuit-switched and packet-switch traffic. Class B stations support
both types of traffic but not simultaneously, while Class C
stations support only one type of traffic. The General Packet Radio Service
provides security services similar to those in
circuit-switched GSM. This means that security is not end-to-end, but
between the mobile terminal and the General Packet Radio Service support node.
Upgrading an existing GSM network typically requires new hardware in
the base station controller (BSC) and a software upgrade to
other parts of the system.
Other topics in our resources on GSM related to General Packet Radio Service include:
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