The General Packet Radio Service (GPRS) is a non-voice service supplied on the GSM mobile phone infrastructure, offering true packet data capability and billing. GPRS benefits from the fact that GSM infrastructure has been widely deployed around the world and that the addition of GPRS capability is of minimal cost.

Other benefits of GPRS include;

• Speed up to 171.2 kilobits per second (kbps)
• "Always On" Connection
• Data Usage is paid for and not connect time
• Broad availability
• International Roaming feature
• GPRS designed to run on well established technology Platform and by well established companies
• Consumers subsidise pricing through GSM network mass usage
• Broad network availability

 Key User Features of GPRS

The General Packet Radio Service (GPRS) is a new non-voice value added service that allows information to be sent and received across a mobile telephone network. It supplements the Circuit Switched Data and Short Message Service (SMS). GPRS is NOT related to GPS (the Global Positioning System), a similar acronym that is often used in mobile contexts. GPRS has several unique features which can be summarized as:

Speed

Theoretical maximum speeds of up to 171.2 kbps are achievable with GPRS using all eight timeslots at the same time. This is about three times as fast as the data transmission speeds possible over today's fixed telecommunications networks and ten times as fast as current Circuit Switched Data services on GSM networks. By allowing information to be transmitted more quickly, immediately and efficiently across the mobile network, GPRS is a less costly mobile data service compared to SMS and Circuit Switched Data.

Immediacy

GPRS facilitates instant connections whereby information can be sent and received immediately as the need arises, subject to radio coverage. No dial-up modem connection is necessary. This is why GPRS users are sometimes referred to be as being "always connected". Immediacy is one of the advantages of GPRS when compared to Circuit Switched Data. High immediacy is a very important feature for time critical applications such as remote credit card authorization where it would be unacceptable to keep the customer waiting for even thirty extra seconds.

New Applications, Better Applications

GPRS facilitates several new applications that have not previously been available over GSM networks due to the limitations in speed of Circuit Switched Data (9.6 kbps) and message length of the Short Message Service (160 characters). GPRS will fully enable the Internet applications you are used to on your desktop from web browsing to chat over the mobile network. Other new applications for GPRS include file transfer and home automation- the ability to remotely access and control in-house appliances and machines.

Key Network Features of GPRS

Packet switching

GPRS involves overlaying a packet-based air interface on the existing circuit switched GSM network. This gives the user an option to use a packet-based data service. To supplement a circuit switched network architecture with packet switching is quite a major upgrade. However, the GPRS standard is delivered in a very elegant manner- with network operators needing only to add a couple of new infrastructure nodes and making a software upgrade to some existing network elements.

With GPRS, the information is split into separate but related "packets" before being transmitted and reassembled at the receiving end. Packet switching is similar to a jigsaw puzzle- the image that the puzzle represents is divided into pieces at the manufacturing factory and put into a plastic bag. During transportation of the now boxed jigsaw from the factory to the end user, the pieces get jumbled up. When the recipient empties the bag with all the pieces, they are reassembled to form the original image. All the pieces are all related and fit together, but the way they are transported and assembled varies. The Internet itself is another example of a packet data network, the most well known of many such network types.

Spectrum Efficiency

Packet switching means that GPRS radio resources are used only when users are actually sending or receiving data. Rather than dedicating a radio channel to a mobile data user for a fixed period of time, the available radio resource can be concurrently shared between several users. This efficient use of scarce radio resources means that large numbers of GPRS users can potentially share the same bandwidth and be served from a single cell. The actual number of users supported depends on the application being used and how much data is being transferred. Because of the spectrum efficiency of GPRS, there is less need to build in idle capacity that is only used in peak hours. GPRS therefore lets network operators maximize the use of their network resources in a dynamic and flexible way, along with user access to resources and revenues.

GPRS should improve the peak time capacity of a GSM network since it simultaneously allocates scarce radio resources more efficiently by supporting virtual connectivity.

Internet Aware

For the first time, GPRS fully enables Mobile Internet functionality by allowing interworking between the existing Internet and the new GPRS network. Any service that is used over the fixed Internet today- File Transfer Protocol (FTP), web browsing, chat, email, telnet- will be as available over the mobile network because of GPRS. In fact, many network operators are considering the opportunity to use GPRS to help become wireless Internet Service Providers in their own right.

The World Wide Web (Web) is becoming the primary communications interface- people access the Internet for entertainment and information collection, the intranet for accessing company information and connecting with colleagues and the extranet for accessing customers and suppliers. These are all derivatives of the Web aimed at connecting different communities of interest. There is a trend away from storing information locally in specific software packages on PCs to remotely on the Internet.

When you want to check your schedule or contacts, instead of using something like "Act!", you go onto the Internet site such as a portal. Hence, web browsing is a very important application for GPRS.

Summary

GPRS will provide a massive boost to mobile data usage and usefulness. That much seems assured from its flexible feature set, its latency, efficiency and speed.

Relative cost of data transfer

Speed of data transfer and its effect on RTU battery life

With the reductions in power consumption achieved the life of the batteries is extended and standard Alkaline LR20 (D size) batteries can be utilised. Also fewer battery changes are required.