Wireless Master

GPRS is one of the most common technologies that are being used by most cellphone as well as Internet users today. GPRS facilitates Internet connectivity on the cellphone and thus lets people access and connect to the Internet at all times. There is certain hardware that supports the use of GPRS. Now, these GPRS compatible devices are subdivided in to three categories.

First one is called Class A devices. These gadgets are developed enough to use both the GPRS and the GSM services at the same time. That is, it uses voice and Short Messaging Service or SMS at the same time. There are many such Class A devices that can be found today.

The second category is the Class B devices which can again be connected to both the GSM as well as the GPRS services, but the difference here is both cannot be used at the same time. Only one service can be used at the same time. One service is suspended as long as the other is being used. For example, if the GSM service is being used, like a voice call or SMS, then the GPRS is temporarily rendered inactive. Once the former is over, GPRS is enabled again. Most of the GPRS enabled mobile phones today are of the Class B category.

Then lastly, there is the third category which is obviously called Class C. This kind of gadget can be connected to either the GPRS service or the GSM service and there can be a manual switching of services as and when the user wishes to.

For a Class A device, there can be a simultaneous transmission of dual frequency. Thus to make things simpler, a mobile phone which is GPRS enabled, uses the DTM facility or the Dual Transfer Mode. If a mobile phone has this, then it means that the device can access both voice data as well as packet data at the same time. The network so co-ordinates it so that two different frequencies do not need to be transmitted at the same time. These kinds of devices are usually called “pseudo Class A” devices or “simple Class A” gadgets.

Let us look at the example of the USB modems. These are GPRS modems and have become very popular among those people who use laptops and therefore need the facility of a wireless internet connection. These wireless modems use USB 2.0 and also formats like V.42bis, RFC 1144 and external antennas as well. They are usually in the form of cards for laptops or as external USB drives.

There are certain factors on which the speed of data transmission depends. One of the first factors is the number of BTS TDMA time slots that are given by the operator of the network. Then there is the maximum level or capability of the gadget which is being used. It can be a wireless device. The last factor is that of the channel encoding which is used.