General Packet Radio Service (GPRS)

   In the year 1999, cellular networks began incorporating GPRS technology into their infrastructure. The service became available in 2001. Initial data-transmission speed ran to around 28 kilobytes per second, but eventually GPRS phones could surf the Web at 60 kilobytes per second. Data packaging makes GPRS cost-efficient, as phone users only pay for bursts of data rather than a steady stream. It doesn't place an excessive drain on the battery while Web surfing or sending text messages.

  When we say GPRS (General Packet Radio Service), it is the world's most ubiquitous wireless data service, available now with almost every GSM network. GPRS is a connectivity solution based on Internet Protocols that supports a wide range of enterprise and consumer applications. With throughput rates of up to 40 kbit/s, users have a similar access speed to a dial-up modem, but with the convenience of being able to connect from anywhere. GPRS customers enjoy advanced, feature-rich data services such as colour Internet browsing, e-mail on the move, powerful visual communications such as video streaming, multimedia messages and location-based services. For operators, the adoption of GPRS is a fast and cost-effective strategy that not only supports the real first wave of mobile Internet services, but also represents a big step towards 3GSM (or wideband-CDMA) networks and services.

    GPRS is a network overlay to the existing cellular network. It uses the nature of IP transmissions to its advantage. Because IP traffic is made of “packets”, the network does not need to have continuous data transmission. Thus, IP traffic can easily share the channels. A user may be receiving or transmitting data while another one is reading information. The second user does not need to use the channel during this time, and it makes packet networks more efficient than circuit-switched networks (2G), where the channel would be in use, regardless of the user transmitting or not. Each channel is divided into eight time slots, with a maximum data transmission of 13.4Kbps.


   GPRS is different from the older mik-mac Circuit Switched Data (or CSD) connection included in GSM standards.In CSD, a data connection establishes a circuit, and reserves the full bandwidth of that circuit during the lifetime of the connection. GPRS is packet-switched which means that multiple users share the same transmission channel, only transmitting when they have data to send. This means that the total available bandwidth can be immediately dedicated to those users who are actually sending at any given moment, providing higher utilisation where users only send or receive data intermittently. Web browsing, receiving e-mails as they arrive and instant messaging are examples of uses that require intermittent data transfers, which benefit from sharing the available bandwidth.  

   Usually, GPRS data are billed per kilobytes of information transceived while circuit-switched data connections are billed per second. The latter is to reflect the fact that even during times when no data are being transferred, the bandwidth is unavailable to other potential users. GPRS originally supported (in theory) IP, PPP and X.25 connections. The last has been typically used for applications like wireless payment terminals although it has been removed as a requirement from the standard. X.25 can still be supported over PPP, or even over IP, but doing this requires either a router to do encapsulation or intelligence built into the end terminal.

   GPRS was developed to enable GSM operators to meet the growing demands for wireless packet data service that is a result of the explosive growth of the Internet and corporate intranets. Applications using these networks require relatively high throughput and are characterized by bursty traffic patterns and asymmetrical throughput needs. Applications, such as web browsing, typically result in bursts of network traffic while information is being transmitted or received, followed by long

idle periods while the data is being viewed. In addition, much more information is usually flowing to the client device than is being sent from the client device to the server. GPRS systems are better suited to meet the demand of this bursty data need than the traditional circuit−switched wireless

data systems.

Advantages Of GPRS

• GPRS is cheaper than through the regular GSM network.
• As GPRS services are available wherever there is GSM coverage, it allows you to connect to the Internet even when other services such as 3G or HSDPA are not available.
• GPRS provides wireless access to the Internet from any location where there is a network signal.
• GPRS is still faster than the older WAP (Wireless Application Protocol) and regular GSM services.
• When you access the Internet through GPRS, it does not block incoming calls through the GSM network.

Disadvantages Of GPRS

• GPRS packet loss phenomena occur 
• the actual rate lower than the theoretical value
• , GPRS 
• data transfer rate to achieve the theoretical maximum 172.2kbps.
• users will pay for traffic services
• modulation is not optimal 
• there is switching delay

Applications of GPRS

• information services as text or graphics
• chat
• still images
• moving images
• web browsing
• audio reports
• LAN application
• internet email
• file transfer
• corporate email
• document sharing and remote collaborative working

Reference:

• http://www.mobilein.com/GPRS.pdf
• http://www.ehow.com/list_7628002_advantages-gprs.html
• http://searchmobilecomputing.techtarget.com/definition/GPRS