Mobile internet extends traditional Internet to wireless devices such as cellular phones and Personal Digital Assistants (PDA's). It brings information and services to the user's fingertips whenever and where ever they need it.
Wireless internet is not just an extension of the internet into the mobile environment, it is an integration of the internet and telecommunication technologies into a single system. GPRS (General Packet Radio Service) is a new technology that has been added to traditional GSM mobile systems to allow for internet access through the cellular networks.
GPRS has complemented current data services offered by GSM's digital cellular networks, providing services promised by next generation cellular companies. It facilitates instant connection to the internet so information can be sent or received immediately, without the need for a dial-up modem.
With GPRS, users roaming anywhere can access the internet simply by connecting their GPRS enabled handsets to the PC through serial, USB, IR port or Blue tooth. Before we actually start off with GPRS let me tell you about two computer networking terms that will be used in this article.
The first is circuit-switched network in which a physical path is established and dedicated to a single connection between two communicating points in the network for the duration of the connection. It is used for ordinary telephone calls.
The other is packet-switched network, in which messages are divided into packets before they are sent. Breaking communication down into packets allows the same data path to be shared among many users in the network. Most traffic over the internet uses packet-switching.
A variety of wireless networks have been used to provide internet access to cellular networks. However they all suffer from a number of problems, which are a result of all Second Generation or 2G cellular systems including GSM systems. These have been designed and optimized for voice communication, leaving very little room for data transfer capabilities.
In 2G cellular systems the voice-friendly, circuit-switching technique has been used. Circuit-switched networks provide ideal quality service to low-bit rate, real time applications that require a constant bit-rate and those who are delay-sensitive, such as IP telephony.
However, the same technique fails to provide efficient bandwidth usage in case of data communication. In particular, dedicating circuits for entire conversations for wireless networks with limited bandwidth is far from being efficient.
Thus, circuit-switching techniques cannot support the burst of data traffic. It is a waste of precious resources to use it in a mobile-computing environment. Moreover, the nature of circuit-switching network is such that users have to pay on the basis of time of connection and not the amount of data traffic transmitted. The use of cellular radio interface to connect to the internet comes together at high cost for users.
On the other hand, a circuit- switched network presents a very unfriendly environment for transmitting TCP/IP packets which are at the heart of the internet. GSM, for example, can handle data traffic only up to 9.6 kbps, which is far below current rates in wired networks. This is simply too low and unacceptable for majority of the internet users.
GPRS, as a network with packet-switched core architecture, came to resolve packet transmission problems raised in GSM systems. It is just an evolution of the GSM system that uses packet-switched technology. Unlike GSM, however, it targets data applications such as web and e-mail services and offers higher data rates and bandwidth.
GPRS allows the sending and receiving of data in an end-to-end packet transfer mode without using any resources in circuit-switched mode. As a result, packet mode data applications can be supported by GPRS much more efficiently than by phase II GSM systems. In particular, applications that exhibit frequent non-periodic data transmissions in small chunks or packets are very well-suited to GPRS.
The advantage of a packet- based approach is that GPRS only uses radio link for the time that data is being sent or received. This means that multiple users can share same radio channels very efficiently. As opposed to this, circuit-switched connections provide users with dedicated connections during the entire call, irrespective of whether they are sending data or not.
With GPRS, users will only pay for the amount of data they actually communicate. In fact, users can be virtually connected to the network all the time without incurring any charges, which is very beneficial.
Theoretically, maximum speeds of up to 171.2 kbps are achievable with GPRS. This is about three times faster than data transmission speeds possible over today's fixed networks and ten times faster than services offered by GSM networks.
By allowing information to be transmitted quickly and efficiently across the mobile network, GPRS is a relatively cheaper mobile service as compared to circuit-switched data. The high speed offered by GPRS will finally make transmission of multimedia content, including graphics, voice and video over cellular networks practical.
Unlike GSM, GPRS also acts as an ideal bearer of WAP to transfer internet content directly to mobile phones or handheld devices. Charges are nominal if you access GPRS over WAP, considering that you are billed on the amount of data you send and receive (WML pages are usually not larger than a few kilobytes). However, using GPRS to browse the web can be a bit costly, depending on the graphic and multimedia content present on the web pages you visit.
GPRS can also be considered as the first step towards wide area wireless internet, as packet-switching provides a seamless and immediate connection from a mobile PC to the internet
Another advantage of GPRS is that it keeps the same radio modulation as GSM as well as frequency bands. Voice calls can also be made simultaneously over GSM networks while GPRS connections are being operated.
With respect to the air interface, GPRS allows several mobile terminals to be multiplexed on to a single basic physical channel. However, it also offers multi-slot capability, allowing a single mobile station to use many slots at a time.
This allows a wide range of data rates to be supported from very low rates to more than 100 kbit/s. All resources are assigned to individual users when they need to transmit data which saves the network from overloading.
ß You may want to skip the GPRS network infrastructure details given in italics à. For GPRS, two additional network elements are integrated in the GSM system - Serving GPRS Support Nodes (SGSN) and Gateway GPRS Support Nodes (GGSN). As the name suggests, GGSN act as a gateway between the GPRS network and external data networks e.g.
GGSN encapsulates packets received from external packet networks (IP) and routes (directs) them to SGSN. The IP address allocated to mobile stations also points towards GGSN. SGSN operates as a router for data packets for all mobile stations present in a given area, keeps track of the location of individual mobile stations and performs security functions.
Different mode of operations are supported for GPRS mobiles. Mobiles can support GPRS and GSM data services simultaneously. They can operate either as normal GSM mobile terminals, or as GPRS-only terminals depending on user choice.
Internet and wireless communications are converging to meet the demand for twenty-four hour access to information. GPRS and other mobile systems are expected to offer increasing bit-rates aimed at data and multimedia transmission, with mobile terminals based on a combination of functions seen in PCs and mobile phones, voice capability being just one of the features.
Continuing progress in data communication offered by GPRS and along with bringing IP-based services to cellular networks, will probably lead to the outnumbering of internet-capable PCs by internet-capable mobiles. It is quite possible that by the end of the decade PCs will be only one among several different terminals for home access to the internet.