What is GPRS?

GPRS (General Packet Radio Service) is built upon the worldwide accepted and successful GSM technology and is often called 2.5G. It is available on nearly all of the worlds GSM based networks. GPRS is as the name implies, a packet based system that sends data in chunks that is reconstructed at the termination end into the data originally sent. This is different to GSM which is a point to point style connection and data is essentially sent in a sequential stream.
GPRS only uses network resources and bandwidth during data transmission, so the operator saves network extension costs. It is therefore well suited for a range of personalized applications and value-added services that require bulky and bursty data transfer such as mobile Internet, electronic banking, and location-based services.
To use a basic analogy – GSM data transmission is similar to using a desktop style dial up modem. It takes time to connect, is slower and you typically pay for the time you are connected.
GPRS is more akin to broadband data transmission. I.E your broadband PC connection at home or in the office. Once you connect you are ‘always on’, constantly connected. It gives you a higher data throughput and you are charged by the amount of data sent, not by the amount of time online.

GPRS is broken down into different Multislot CLASSES. These determine the amount of available channels for data flow in both an uplink and downlink situation.

Examples of the Multislot Classes

Depending on the hardware used, in many cases, the Up and Down slots can be configured to improve data transfer in a specific direction.

Regarding data transmission speeds. It is really a misnomer to say that GPRS (and EDGE) transmits data faster. What they essentially do is to allow more data through but going at the same speed. A simple analogy is to think of your data transmission slot as a single lane road. One man in a car (driver = chunk of data) at a time going at a set speed up the road. To send more data, more transmission slots are made available, i.e. more lanes are opened. The data (The cars and drivers) is going at the same speed, but obviously more can be transmitted via the large number of time slots available.
More data can also be transmitted by using compression routines. Here all you need do is to think of each car on each carriageway having say, four people inside instead of just the driver. Therefore, more data is being transmitted even though it is still moving at the same speed.

What is EDGE?
EDGE (Enhanced Data rates for GSM Evolution) is a new modulation scheme that is more bandwidth efficient than the modulation scheme used in the GSM standard. Basically it is squeezing more timeslots into the given space by using new routines. EDGE is an ITU-accredited 3G standard and is an enhancement of GPRS to triple data speeds in live practical commercial environments. Due to the very small incremental cost of including EDGE capability in GSM network deployment, virtually all new GSM infrastructure deployments are also EDGE capable. Whether this is fact for the UK is debatable. The rumour is that the networks are not going to promote EDGE in the UK due to their desire to claw back some of the massive costs entailed during the bid war for licences a few years back. EDGE would not provide them the pay back.. allegedly!

EDGE is an ideal solution for applications requiring middle and high data throughput such as:
• Messaging services
• Video and Audio Download
• Video and Audio Stream
• Video Telephony
• ePaper
• Financial services
EDGE is similar to GPRS in that it is always connected and data is paid for on a quantity basis.