GPRS is a value added service and it provides a wide range of bandwidth that’s why it supports numerous high bandwidth services like video conferencing etc. GPRS services are billed on the per KB/s data transfer basis.
There are some limitations, deployment and operational issues that are related to the quality of service, handset availability, network optimization and charging of service. General Packet Radio Service is supported by the point to point protocol, internet protocol and X.25 connections.

GPRS users are referred to as “always connected” because no prior connection establishing is required such as dialing up a modem etc. A larger number of the subscribed users share the same radio resources and high bandwidth. High data transfer speed is among the major features of the GPRS and theoretically it supports up to 171.2 Kb/s by using all the eight time slots at the same time and it make it relatively less costly as compared to the circuit switched networks. The data packets are splitted into the smaller related packets that are reunited at the receiving end.

It also supports the new applications that were not supported by the circuit switched network due to the speed limitations.

GPRS Requirements

To use the GPRS connection you need the following things.

* GSM enabled mobile phone
* Subscription to the mobile network that supports GSM/GPRS.

Supported Applications

Following are some of the major applications that are supported by the General Packet Radio Service.

* Web browsing
* Moving Images
* Simple Messaging Service
* Files Sharing
* Vehicle positioning
* Home Automation
* Remote LAN access
* Emails
* Vehicle Positioning

Benefits of GPRS Technology

* It supports the minimal upgrade to the existing GSM network.
* It supports the larger messages length as compared to the SMS.
* It supports the VPN and corporate sites access through internet.
* It supports the packet based air interface over the existing circuit switched GSM network.
* It supports high speed data transfer in an “always connected” mode.

If want to connect your computer with the GPRS mobile phone then you can do this by the following methods.

* Bluetooth
* Infrared
* Data Cable

GPRS is a commonly used mobile communication technology for almost all mobile phones in all over the world. It is instantly available and relatively less costly mobile communication service.

This is where CDMA technology fits in. CDMA consistently provides better capacity for voice and data communications than other commercial mobile technologies, allowing more subscribers to connect at any given time, and it is the common platform on which 3G technologies are built.

CDMA is a “spread spectrum” technology, allowing many users to occupy the same time and frequency allocations in a given band/space. As its name implies, CDMA (Code Division Multiple Access) assigns unique codes to each communication to differentiate it from others in the same spectrum. In a world of finite spectrum resources, CDMA enables many more people to share the airwaves at the same time than do alternative technologies.

The CDMA air interface is used in both 2G and 3G networks. 2G CDMA standards are branded cdmaOne and include IS-95A and IS-95B. CDMA is the foundation for 3G services: the two dominant IMT-2000 standards, CDMA2000 and WCDMA, are based on CDMA.

GSM (Global System for Mobile communications) is an open, digital cellular technology used for transmitting mobile voice and data services.

What does GSM offer?

GSM supports voice calls and data transfer speeds of up to 9.6 kbit/s, together with the transmission of SMS (Short Message Service).

GSM operates in the 900MHz and 1.8GHz bands in Europe and the 1.9GHz and 850MHz bands in the US. The 850MHz band is also used for GSM and 3G in Australia, Canada and many South American countries. By having harmonised spectrum across most of the globe, GSM’s international roaming capability allows users to access the same services when travelling abroad as at home. This gives consumers seamless and same number connectivity in more than 218 countries.

Terrestrial GSM networks now cover more than 80% of the world’s population. GSM satellite roaming has also extended service access to areas where terrestrial coverage is not available.

These are all questions most people don’t ask themselves. Most of us take cell phones for granted. As long as we can talk to who we want, when we want, then we don’t need to be concerned about how the call is made. So we’re going to talk about how cell phones work. We believe that if you have a knowledge of something you’re using, you somehow appreciate it more.

Cell Phones – radios, what’s the difference?

Cell phones are actually radios. They broadcast their signals on radio frequencies. So what’s the difference? Let’s compare. First, we’ll look at how radios work. You’re probably familiar with CBs or walkie-talkies. And you probably know that only one person can talk at once, and the frequency is shared by just the two of you. This system of transmitting radio signals on a single frequency is known as a simplex system.

Cell phones operate on a duplex system, which uses two frequencies – one for talking or sending, and one for listening or receiving. That’s the basic difference between radios and cellphones. Another difference worth noting is that CB radios have 40 channels. Cell phones can use up to 1,664 channels. Its obvious that cell phone technology, although basically similar to radio technology, is much more sophisticated.

Cell phones transmit signals over the airwaves

To understand the transmission of radio signals, you’ll need to understand frequencies. Think of the entire width of the airwaves, referred to as the spectrum, as being split up into numerous strips. Each strip is a frequency, capable of transmitting electric currents containing signals. Blocks of frequencies, referred to as the bandwidth, are designated for various transmissions. Cell phones have been assigned a bandwidth in which to transmit their signals. But with the number of cell phones, and the number of calls competing for airtime, something needed to be done to expand their airspace.

Digital technology – an improvement over analog

Because expansion of the airwaves wasn’t an option, cell phone technologists had to come up with another solution. So what they did was split the available bandwidth. And the way they did that was to convert the analog signal into a digital signal. To understand the scope of this change, think of audio cassettes compared to CDs – cassettes are analog; CDs are digital. And look at how much more data you can store on a CD than on a cassette. That’s how cell phones can send more digital signals without interference.
Cell Phone signals “get around”

A cellular transmission does indeed get around. And this is how it goes. Cellular systems are made up of a series of geographical areas, called cells (thus the name of the phone). Within these cells are a number of assigned channels. These channels can be used by different cells, as long as they’re not too close to each other. If two cells were using the same channel at the same time, and if they were too close to each other, they would interfere with each other. That’s why the channels are carefully assigned, so as to minimize interference. So the big advantage to this is that the same channel can be used all across the country, without interference. In that way, use of the available bandwidth is maximized.

The technology behind the transmission of cellular signals is fairly-easily understood. Remember analog systems, that split their assigned bandwidth into channels; each channel can be used by only one caller at once. The next advancement of this technology digitally splits the calls using different frequencies and times, thus allowing you to transmit three calls within one channel.

Now, the latest digital technology doesn’t use channels at all. What it does, is send out the signals in code, which can be scattered throughout the whole spectrum, using only the piece that it’s currently occupying. The receiver, the cell phone at the other end, can gather up this data by decoding it and translating it back to its original sound – your voice.

And remember that call that goes all the way around the world? It gets there using the same technology that it does to go around the block. The difference is that signals that travel around the world are sent and received by satellite. Satellite technology is touching every part of our lives these days, and cell phones are no exception.

How Your Cell Phone Recognizes The Caller

When your cell phone is manufactured, it’s assigned an Electronic Serial Number (ESN). This number stays with your phone for it’s whole life. No matter what phone number is actually assigned to your phone, the ESN remains the same. The ESN is important because that’s how the cell phone system knows it’s you that’s placing a call, or that you’re the one someone else is calling.

Every time you phone somebody, a central system identifies you as the caller. The identification process includes making sure your account is in order – like if you’ve paid your bill). If everything checks out, then the system connects you and assigns your signal to any frequency that’s open at the time, and off it goes.

What happens when there’s no signal?

Sometimes, when you’re traveling with your mobile phone, you go through “dead spots” where you get a “No Service” message. Remember the cells in each area? Well, these cells are connected by towers that send and receive signals. As you travel, the system automatically transfers your cellular from one cell to another, so that you’re always in range of a tower. However, there are a few areas where there’s too much distance between towers, usually in remote areas. When you get caught in one of those areas, the signal from your phone cant find a tower to receive it, and you have “No Service”.

This also brings up “roaming”. Your phone is programmed to operate toll-free within a certain area. If you leave that area, the tower that receives your signal doesn’t recognize your phone as belonging to that area. So it makes your connection, notifies you on the display of your phone that you’re “roaming”, and automatically charges you extra for it.

Today’s Cell Phones Are Amazing!

So that’s the basics of how cell phones work. And cellular technology is rapidly advancing. Now you can do all kinds of things with your phone. You can send text messages. You can download ring tones. You can even buy a cell phone camera and take pictures with it, which you can then send to your family and friends. As technology advances even further, you’ll soon be able to operate half your life from your phone.

There are hundreds of online cell phone merchants; the Internet has become the place to shop for a phone. Check out all the new models and options available. And next time you’re making a call on your phone, think of how cell phones work – it’ll make you appreciate it more.