September 30, 2008 at 16:44GPRS - theory and practice of application
It just so happened that I have been using unlimited GPRS since the end of last year, which allows me to confidently share my experience with readers.
A bit of theory
GPRS (General Packet Radio Service - General Packet Radio Communication) is an add-on to GSM mobile communication technology that allows you to organize the exchange of mobile phone information with the Internet.
The principle of GPRS is as follows: information is collected in packets before transmission, packets are transmitted at the moment the GSM voice channel is released, which allows the telecom operator to more effectively use the capabilities of the GSM network. In most GSM networks, priority is given to voice traffic, which means a low data rate with a high network load.
To learn more
GPRS packets can be transmitted simultaneously over several free communication channels. The number of simultaneously used input and output channels (time slots) determine the class of GPRS. Also, depending on the quality of the channel, one of four coding schemes can be selected (with a good signal-to-noise ratio, a coding scheme with a higher transmission rate but with less noise immunity is selected). I combined the data on the classes and coding schemes of GPRS into the corresponding tables.
Based on the data in the tables, it can be determined that the maximum data rate is 85 kilobits per second for GPRS Class 10. The transmission speed in most GPRS classes is lower, and the total number of channels used for transmitting and receiving is limited.
Choosing a GPRS modem
After a short insight into the theory of mobile packet data, you can move on to such an entertaining task as choosing a GPRS modem.
There is a fairly large class of USB and PC-Card GPRS modems, however, the availability of these devices is quite low, and the cost of such a truncated mobile is decent. Many modems are already sold with built-in firmware for a particular telecom operator, which can create problems when changing your telephone company.
For most users, it makes sense to buy a used cell phone with GPRS support, and use it as a modem. This option will allow not only to use the capabilities of mobile Internet access, but also to acquire an additional voice communication option. What should you pay attention to?
First, the phone must support GPRS class 8 or 10. It is these phones that can use all the GPRS capabilities for receiving data. Older phones with support for low-end GPRS are better not to purchase.
Secondly, it is desirable for the phone to have rich communicative abilities - Bluetooth, IrDA ports, as well as the presence of a USB or COM data cable.
Thirdly, the phone and the data cable should support charging while working with the data cable, which will allow you to confidently use such a modem for a long time, without looking at the level of battery discharge.
Fourth, and most importantly - the phone must be working - as with the purchase of any other used item, you should make sure that the part of the phone for which it is purchased is operational.
At one time, I opted for a Sony Ericsson T610 phone (it was my second T610, at first I often confused them) - a phone in an aluminum case with support for GPRS Class 8, Bluetooth, IrDA, USB and COM data cables. It cost me 90 thousand Belarusian rubles, when checking it turned out that the built-in camera of the phone did not work, this did not affect the modem’s performance, but this option greatly reduced the price.
Installing and configuring a GPRS modem
Installing and configuring a GPRS modem is not difficult - the built-in filling of both a mobile phone and a separate GPRS modem is a regular hardware COM modem, which is detected and installed “with a bang” by any modern operating system.
After installing the SIM card in the phone, you will need to configure the settings of the Internet access point. Many mobile service providers provide automatic configuration service. If you are at a loss to configure these parameters - contact the support service of your service provider.
What should I know about installing the phone as a GPRS modem for Windows?
When connecting via COM with a data cable or infrared port (IrDA), you will need to specify the path to the modem-scripts file for your phone in the Add New Modem Wizard. If you don’t have such a file, then type in the phrase: “modem-scripts model of your phone download” in any search engine and download the desired file using the search results. After installing the modem, write in the initialization line the data provided by your service provider. After these simple steps, the modem configuration can be considered complete. Further, all Internet access actions are identical to those for dial-up communication.
If you are unhappy (happy?) The owner of the USB data cable, get ready for the fact that in most USB data cables the connection to the phone is via the same serial COM port (USB-to-microcircuit is installed in such USB data cables Com). The consequence of this circumstance is the need to install a driver to interface with the USB-to-COM chip. If you managed to find the appropriate driver on the CD supplied with the data cable, then further installation of the modem will not be a problem.
The most enjoyable way to use a GPRS modem of a cell phone is to access via a Bluetooth port. If your computer has a Bluetooth adapter, then the configuration will be to establish a connection between the computer and the phone, prescribe a PIN code for communication and, in some cases, install a modem-scripts file and prescribe an initialization line for the modem.
In the event that you buy external USB Bluetooth, be careful - for some models, drivers with reduced functionality are included (the full version will cost extra money). It may be the best way to get USB Bluetooth without drivers in the kit if something like this is written on the box: “No additional drivers are required to install the device, the device is compatible with Windows XP / 2000 / Vista.” In any case, negotiate with the seller about the possibility of checking the device before buying.
Conclusion
Mobile Internet is getting cheaper, high-speed communication parameters are improving. Soon, many readers will be able to taste the delights of the "Internet without wires." I hope that this brief overview of the possibilities of mobile access in GSM networks has given you the necessary minimum knowledge for practical use.
For those who want to learn more about working with GPRS under Linux and what EGPRS is - the full version of the article: GPRS - theory and practice of application
A bit of theory
GPRS (General Packet Radio Service - General Packet Radio Communication) is an add-on to GSM mobile communication technology that allows you to organize the exchange of mobile phone information with the Internet.
The principle of GPRS is as follows: information is collected in packets before transmission, packets are transmitted at the moment the GSM voice channel is released, which allows the telecom operator to more effectively use the capabilities of the GSM network. In most GSM networks, priority is given to voice traffic, which means a low data rate with a high network load.
To learn more
GPRS packets can be transmitted simultaneously over several free communication channels. The number of simultaneously used input and output channels (time slots) determine the class of GPRS. Also, depending on the quality of the channel, one of four coding schemes can be selected (with a good signal-to-noise ratio, a coding scheme with a higher transmission rate but with less noise immunity is selected). I combined the data on the classes and coding schemes of GPRS into the corresponding tables.
| GPRS Class | Reception channels | Transmission channels | Total |
| 1 | 1 | 1 | 2 |
| 2 | 2 | 1 | 3 |
| 3 | 2 | 2 | 4 |
| 4 | 3 | 1 | 4 |
| 5 | 2 | 2 | 4 |
| 6 | 3 | 2 | 4 |
| 7 | 3 | 3 | 4 |
| 8 | 4 | 1 | 5 |
| 9 | 3 | 2 | 5 |
| 10 | 4 | 2 | 5 |
| eleven | 4 | 3 | 5 |
| 12 | 4 | 4 | 5 |
| Coding scheme | Maximum speed (Kbps) |
| CS1 | 9.05 |
| CS2 | 13.4 |
| CS3 | 15.6 |
| CS4 | 21.4 |
Based on the data in the tables, it can be determined that the maximum data rate is 85 kilobits per second for GPRS Class 10. The transmission speed in most GPRS classes is lower, and the total number of channels used for transmitting and receiving is limited.
Choosing a GPRS modem
After a short insight into the theory of mobile packet data, you can move on to such an entertaining task as choosing a GPRS modem.
There is a fairly large class of USB and PC-Card GPRS modems, however, the availability of these devices is quite low, and the cost of such a truncated mobile is decent. Many modems are already sold with built-in firmware for a particular telecom operator, which can create problems when changing your telephone company.
For most users, it makes sense to buy a used cell phone with GPRS support, and use it as a modem. This option will allow not only to use the capabilities of mobile Internet access, but also to acquire an additional voice communication option. What should you pay attention to?
First, the phone must support GPRS class 8 or 10. It is these phones that can use all the GPRS capabilities for receiving data. Older phones with support for low-end GPRS are better not to purchase.
Secondly, it is desirable for the phone to have rich communicative abilities - Bluetooth, IrDA ports, as well as the presence of a USB or COM data cable.
Thirdly, the phone and the data cable should support charging while working with the data cable, which will allow you to confidently use such a modem for a long time, without looking at the level of battery discharge.
Fourth, and most importantly - the phone must be working - as with the purchase of any other used item, you should make sure that the part of the phone for which it is purchased is operational.
At one time, I opted for a Sony Ericsson T610 phone (it was my second T610, at first I often confused them) - a phone in an aluminum case with support for GPRS Class 8, Bluetooth, IrDA, USB and COM data cables. It cost me 90 thousand Belarusian rubles, when checking it turned out that the built-in camera of the phone did not work, this did not affect the modem’s performance, but this option greatly reduced the price.
Installing and configuring a GPRS modem
Installing and configuring a GPRS modem is not difficult - the built-in filling of both a mobile phone and a separate GPRS modem is a regular hardware COM modem, which is detected and installed “with a bang” by any modern operating system.
After installing the SIM card in the phone, you will need to configure the settings of the Internet access point. Many mobile service providers provide automatic configuration service. If you are at a loss to configure these parameters - contact the support service of your service provider.
What should I know about installing the phone as a GPRS modem for Windows?
When connecting via COM with a data cable or infrared port (IrDA), you will need to specify the path to the modem-scripts file for your phone in the Add New Modem Wizard. If you don’t have such a file, then type in the phrase: “modem-scripts model of your phone download” in any search engine and download the desired file using the search results. After installing the modem, write in the initialization line the data provided by your service provider. After these simple steps, the modem configuration can be considered complete. Further, all Internet access actions are identical to those for dial-up communication.
If you are unhappy (happy?) The owner of the USB data cable, get ready for the fact that in most USB data cables the connection to the phone is via the same serial COM port (USB-to-microcircuit is installed in such USB data cables Com). The consequence of this circumstance is the need to install a driver to interface with the USB-to-COM chip. If you managed to find the appropriate driver on the CD supplied with the data cable, then further installation of the modem will not be a problem.
The most enjoyable way to use a GPRS modem of a cell phone is to access via a Bluetooth port. If your computer has a Bluetooth adapter, then the configuration will be to establish a connection between the computer and the phone, prescribe a PIN code for communication and, in some cases, install a modem-scripts file and prescribe an initialization line for the modem.
In the event that you buy external USB Bluetooth, be careful - for some models, drivers with reduced functionality are included (the full version will cost extra money). It may be the best way to get USB Bluetooth without drivers in the kit if something like this is written on the box: “No additional drivers are required to install the device, the device is compatible with Windows XP / 2000 / Vista.” In any case, negotiate with the seller about the possibility of checking the device before buying.
Conclusion
Mobile Internet is getting cheaper, high-speed communication parameters are improving. Soon, many readers will be able to taste the delights of the "Internet without wires." I hope that this brief overview of the possibilities of mobile access in GSM networks has given you the necessary minimum knowledge for practical use.
For those who want to learn more about working with GPRS under Linux and what EGPRS is - the full version of the article: GPRS - theory and practice of application