Ø General
Packet Radio Service
Ø Step
to efficiently transport high-speed data over the current GSM and TDMA-based
wireless network infrastructures
Ø Deployment
of GPRS networks allows a variety of new applications ranging from mobile
e-commerce to mobile corporate VPN access
Ø GPRS
allows for data speeds of 14.4 KBps to 171.2 KBps, which allow for comfortable
Internet access
Ø Allows
for short ‘bursty’ traffic, such as e-mail and web browsing, as well as large
volumes of data
Ø No
dial-up modem connection is necessary
Ø Offers
fast connection set-up mechanism to offer a perception of being ‘always on’ or
‘always connected’
Ø Immediacy
is one of the prime advantages of GPRS.
v GPRS Network Architecture
Ø GPRS
uses the GSM architecture for voice
Ø To
offer packet data services through GPRS, a new class of network nodes called
GPRS support nodes (GSN) are introduced
Ø GSNs
are responsible for the delivery and routing of data packets between the mobile
stations and the external packet data networks (PDN)
Ø Two
main GSNs are Serving GSN (SGSN) and Gateway GSN (GGSN)
v GGSN
Ø GGSN
acts as an interface between the GPRS backbone network and the external packet
data networks and functions like a router in a LAN
Ø GGSN
maintains routing information that is necessary to tunnel Protocol Data Units
(PDUs) to the SGSNs that service particular mobile stations
Ø GGSNs
convert the GPRS packets coming from the SGSN into the appropriate packet data
protocol (PDP) format for the data networks like Internet or X.25
Ø GGSN
stores the current SGSN address of the user and user’s profile in its location
register while performing authentication and charging functions related to data
transfer
v SGSN
Ø SGSN
is at the same hierarchical level as the MSC and so, whatever MSC does for
voice, SGSN does for packet data
Ø SGSN’s
tasks include packet switching, routing and transfer, mobility management,
logical link management, authentication and charging functions
Ø SGSN
processes registration of new mobile subscribers and keeps a record of their
location inside a given service area
Ø Location
register of the SGSN stores location information (like current cell, current
VLR, etc.) and user profiles of all GPRS users registered with this SGSN
Ø SGSN
sends queries to HLR to obtain profile data of GPRS subscribers
