What does the acronym GPRS stand for?
What is GPRS?
How is GPRS different to normal data call?
How fast is GPRS?
When will GPRS be available?
Will existing mobiles be able to use GPRS?
Will other devices such as laptops be able to use GPRS?
How will the networks charge for GPRS?
Can I make a voice call while my GPRS handset is receiving data?
What's the next step after GPRS?
What does the acronym GPRS stand for?
General Packet Radio Service.
What is GPRS?
GPRS is a system of transferring information over the GSM mobile phone network
in small packets. e.g. an email
would be broken down into lots of little packets of information and then sent
over the network. Each packet is given
an extra bit of information that tells the network where it is meant to be going
and how it fits into the overall structure
of the original email. This means that the packets can be routed via different
parts of the network taking advantage of
spare capacity and re-assembled at the destination in the right order. This
is exactly the same method used on the
Internet for moving information around.
How is GPRS different to normal data call?
A cell site splits radio channels into timeslots with each timeslot having
the capacity to move data at 9.6Kbs. When a normal or circuit switched data
call is made, the user occupies the whole timeslot and gets the whole 9.6Kbs
to themselves. In other words they have switched the circuit on and it is all
theirs. If there are as many users as the cell site can handle and another user
tries to place a voice or data call then they get the "network busy"
tone or signal and will have to try later. Circuit switched calls are good in
that you get the timeslot all to yourself and hence a pretty much guaranteed
data rate of 9.6Kbs but you are paying for the call the whole time you are connected.
There is also a lengthy process called a "handshake" at the start
of each call to establish a connection.
There is a method of linking several timeslots together to give multiples of 9.6Kbs and this is called High Speed Circuit Switched Data though it is unlikely that many networks are going to implement this as it takes alot of capacity away from the network.
GPRS on the other hand does not take control of a whole timeslot when you have data to be sent or received. Instead, it sends your packets of information out onto the network whenever there is capacity. This is a good and a bad thing! If the cell site is very busy then there may not be much room to send many of your packets and your effective data speed may be reduced - however, GPRS will keep trying to send and receive data all the time leaving you free to carry on working while it takes care of sending the information. When the cell is not busy the data will move much faster. The other major advantage of GPRS over circuit switched data is that it will appear to a user that they are always connected to the network. There is no handshake to perform. As soon as you have data to send or receive the packets start to flow.
How fast is GPRS?
There have been all sorts of figures given as the speed of GPRS. As we have
mentioned above, in the real world, the speed of GPRS will be very much dependant
on how many people are using the mobile network at any one time as well as the
quality of coverage. Another capacity issue will be the configuration of GPRS
handsets - GPRS handsets will be capable of using more than one timeslot for
their packets of data in both the send and receive mode. The most typical configuration
will be 4 timeslots for receiving data and 1 timeslot for sending data. This
is a typical ratio for sending email or browsing the internet. If the user had
the timeslots to themselves then they could get up to 38.4Kbs when receiving
data which is comparable to a standard modem. Of course it would be rare to
have all the timeslots free though the ability to use up to four timeslots and
the packet nature of GPRS means that packets can be inserted into the timeslot
whenever there is spare capacity. Unlike circuit switched data calls, many GPRS
users can share timeslots.
When will GPRS be available?
All four UK networks are looking to implement a GPRS solution, however they
are at various stages.?
BT Cellnet launched a trial GPRS system in June 2000 and have a number of
corporate users testing their system
Vodafone have a trial system and will launch a nationwide service early in 2001
Orange and one2one are both currently trialling GPRS with no firm date for launch
It is wise to note that all networks are looking at businesses to be their first customers for GPRS with consumers following on some months later.
Will existing mobiles be able to use GPRS?
No, GPRS will require new handsets.
Will other devices such as laptops be able to use GPRS? ?
Yes, either by linking to GPRS mobile phones using infra red, cables or
Bluetooth, or by using GPRS PCMCIA cards or other similar devices.
How will the networks charge for GPRS?
As the networks are only currently trialling the GPRS system there is no
fixed method of charging for it. However, it is likely that there are two basic
methods that will be used.
In all likelihood there will probably be various combinations of these. i.e. you pay a high monthly GPRS surcharge with no limit on how much data you transfer. You pay a medium monthly GPRS surcharge and after you have accessed a certain amount of data you are charged per further unit of data transferred. You pay a low or zero GPRS surcharge and you are charged for all units of data transferred.
Can I make a voice call while my GPRS handset is receiving data?
There are 3 classes of GPRS devices or mobile phones.
Class 1 - Simultaneous GPRS and GSM - This type can send and receive data whilst also making voice calls. So for example, you could download an email whilst confirming on the phone that you had received it.
Class 2 - GPRS and GSM - This type can send and receive data and make voice calls but not at the same time.
Class 3 - GPRS only - This type is GPRS only and would be used in something like a PDA, laptop PCMCIA card or vertical market applications like vending machines where there is a need to transfer data but not for voice.
Whats the next step after GPRS?
The next major technology change after GPRS will be the implementation of
a completely new mobile phone system called UMTS or Universal Mobile Telephone
System. Like GPRS, this will be packet based but have a much higher capacity
than current systems. See the UMTS FAQ section for more information.
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