General Packet Radio
Services
With GPRS it is possible to combine 1-8 physical
channel for one user. Various new coding schemes with transmission rates of up
to 21.4Kbits/s per physical channel enable theoretical transmission rates up to
171.2 Kbits/s.
GPRS is a packet-switched bearer service, meaning that
the same physical channel can be used for different subscribers. GPRS is
resource efficient for applications with a short-term need for high data rates
(e.g. surfing the internet, E-mail,…). GPRS also enables point-to-multipoint
transmission and volume dependent charging.
The GPRS system provides a basic solution for Internet
Protocol (IP) communication between Mobile Stations (MS) and Internet Service
Providers (ISP) or a corporate LAN (Local Area Network). GPRS establishes an
end-to-end IP connection from the mobile terminal to the servers at the ISP.
The packet data transmission is thus carried out on an end-to-end basis,
including the air interface.
GPRS users can remain on-line without continuously
occupying a specific radio channel. The same physical channels will be used but
in a more efficient way since several GPRS users will be able to share one
channel.Volume-based charging is possible because channels are allocated to
users only when packets are to be sent or received.
GPRS offers the following:
-Enhancement of GSM data transfer capabilities.
-A new kind of data of ''data-pipe''.
-A new set of bearer services.
-Focus on IP networking.
-Quality of Service categories.
-Packet switching technology.
-Efficient use of air interface resources.
-Volume based traffic.
-Always connected.
-High data rate.
GPRS Services are defined to fall in one two
categories: PTP (Point-To-Point) and PTM (Point-To-Multipoint) services:
·
PTP (Point-To-Point) Services:
GPRS will
support applications based on IP. Applications based on the Connection Oriented
Network Protocols are also defined to be supported.
·
PTM (Point-To-Multipoint) services:
The PTM
services provide the subscribers with the capability to send data to multiple
destinations within one single service request.
Applications:
It is probable that once a wireless Internet
infrastructure is in place, it will be used in ways that we cannot predict.
This is all the more likely as parallel developments in technology will, for
example, raise the computing of a wireless terminal by a factor of hundreds.
- With GPRS a
new complete solution to mobile computing is available.
- It is impossible to build cars with GPRS
communication facilities.
- This would
provide GPRS subscribers with the opportunity to utilize their laptops while
traveling on the bus or train.
- GPRS will make the work of journalists and
photographers easier and cheaper.
The Serving GPRS Support Node SGSN is on the same
hierarchic level as MSC and has functions comparable to those of a Visited MS
(VMSC).
The Gateway GPRS Support Node GGSN has functions
comparable with those of a Gateway MSC (GMSC) and offers interworking functions
for establishing contact between the GMS1 GPRS-PLMN and external packet data
networks PDN.
In the BSS a Packet Control Unit PCU ensures the
reception 1 adaptation of packet data form SGSN into BSS and vice versa.
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