GPRS - Theory and Practice of Application
It so happened that I use unlimited GPRS since the end of last year, which allows us to confidently share my experience with readers.
A bit of theory
GPRS (General Packet Radio Service - public packet radio) is an add-on over GSM mobile communication technology that allows you to exchange mobile phone information with the Internet.
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The principle of GPRS operation is the following: information is collected in packets before transmission, packets are transmitted at the time of the release of the GSM voice channel, which allows the service provider to more effectively use the capabilities of the GSM network. Most GSM networks give priority to voice traffic, which means a low data rate with a high network load.
To learn more
GPRS packets can be transmitted 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 chosen (with a good signal-to-noise ratio, a coding scheme is chosen with a higher transmission rate, but with less resistance to interference). I consolidated 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 reception speed is 85 kilobits per second for GPRS Class 10. The transmission speed is lower in most GPRS classes, and the total number used for transmission and reception of channels is limited.
GPRS modem selection
After a brief insight into the theory of mobile packet data, you can move on to such an entertaining lesson as choosing a GPRS modem.
There is a fairly large class of USB and PC-Card GPRS modems, but the availability of these devices is quite low, and the cost of such a stripped-down mobile is decent. Many modems are already sold with firmware for a specific carrier, 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 possibilities of mobile Internet access, but also to get an additional voice communication opportunity. What should pay attention to?
The first is that the phone must support the GPRS 8 or 10 class. It is these phones that will be able to use all the GPRS capabilities for receiving data. Older phones with low-end GPRS support should not be purchased.
Secondly, the phone should have rich communication skills - Bluetooth, IrDA ports, as well as a USB or COM data cable.
The third is that the phone and data cable must support charging while the data cable is running, which will allow you to confidently use such a modem for a long time without looking back 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 working.
At one time, I chose the Sony Ericsson T610 phone (it was my second T610, I confused them often at first) - the phone in an aluminum case with GPRS Class 8 support, 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 does not work, this did not affect the operation of the modem, but this option greatly reduced the price.
Installing and configuring a GPRS modem
Installing and configuring a GPRS modem does not pose any difficulties - the built-in stuffing of both a mobile phone and a separate GPRS modem is a common hardware COM modem that is defined and installed "with a bang" by any modern operating system.
After installing the SIM card in the phone, you will need to configure the parameters of the Internet access point. Many mobile operators provide an automatic configuration service. If you find it difficult to adjust these parameters, contact the support service of your service provider.
What should I know about installing the phone as a GPRS modem under Windows?
When connecting via COM, a data cable or infrared port (IrDA) will be required in the Add New Modem wizard to specify the path to the modem-scripts file for your phone. If you do not have such a file, then in any search engine, type the phrase: “modem-scripts model_of your_lephone download” and download the required file using the search results. After installing the modem, record in the initialization line the data provided by your service provider. After these simple actions, the modem setup can be considered complete. Further, all actions on Internet access are identical to those for dial-up communication.
If you are unhappy (happy?) With the USB data cable owner, be prepared for the fact that most USB data cables communicate with the phone using the same COM serial port (USB-to-USB chip is installed in these USB data cables Com). The consequence of this circumstance is the need to install a driver for interfacing with a 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 pleasant way to use the GPRS modem of a cell phone is via Bluetooth. If your computer has a Bluetooth adapter, the setting will be to establish a connection between the computer and the phone, prescribing the PIN for communication and, in some cases, installing the modem-scripts file and prescribing the initialization string for the modem.
In that case, if you buy an external USB Bluetooth, be careful - for some models in the kit there are drivers with reduced functionality (the full version will cost extra money). It may be the best way to take USB Bluetooth without drivers in the kit, if something like this is written on the box: "To install the device, no additional drivers are required, 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, improved speed of communication. 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 of knowledge for practical application.
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 - public packet radio) is an add-on over GSM mobile communication technology that allows you to exchange mobile phone information with the Internet.
')
The principle of GPRS operation is the following: information is collected in packets before transmission, packets are transmitted at the time of the release of the GSM voice channel, which allows the service provider to more effectively use the capabilities of the GSM network. Most GSM networks give priority to voice traffic, which means a low data rate with a high network load.
To learn more
GPRS packets can be transmitted 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 chosen (with a good signal-to-noise ratio, a coding scheme is chosen with a higher transmission rate, but with less resistance to interference). I consolidated the data on the classes and coding schemes of GPRS into the corresponding tables.
| GPRS class | Reception channels | Transmission channels | Total |
| one | one | one | 2 |
| 2 | 2 | one | 3 |
| 3 | 2 | 2 | four |
| four | 3 | one | four |
| five | 2 | 2 | four |
| 6 | 3 | 2 | four |
| 7 | 3 | 3 | four |
| eight | four | one | five |
| 9 | 3 | 2 | five |
| ten | four | 2 | five |
| eleven | four | 3 | five |
| 12 | four | four | five |
| 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 reception speed is 85 kilobits per second for GPRS Class 10. The transmission speed is lower in most GPRS classes, and the total number used for transmission and reception of channels is limited.
GPRS modem selection
After a brief insight into the theory of mobile packet data, you can move on to such an entertaining lesson as choosing a GPRS modem.
There is a fairly large class of USB and PC-Card GPRS modems, but the availability of these devices is quite low, and the cost of such a stripped-down mobile is decent. Many modems are already sold with firmware for a specific carrier, 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 possibilities of mobile Internet access, but also to get an additional voice communication opportunity. What should pay attention to?
The first is that the phone must support the GPRS 8 or 10 class. It is these phones that will be able to use all the GPRS capabilities for receiving data. Older phones with low-end GPRS support should not be purchased.
Secondly, the phone should have rich communication skills - Bluetooth, IrDA ports, as well as a USB or COM data cable.
The third is that the phone and data cable must support charging while the data cable is running, which will allow you to confidently use such a modem for a long time without looking back 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 working.
At one time, I chose the Sony Ericsson T610 phone (it was my second T610, I confused them often at first) - the phone in an aluminum case with GPRS Class 8 support, 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 does not work, this did not affect the operation of the modem, but this option greatly reduced the price.
Installing and configuring a GPRS modem
Installing and configuring a GPRS modem does not pose any difficulties - the built-in stuffing of both a mobile phone and a separate GPRS modem is a common hardware COM modem that is defined and installed "with a bang" by any modern operating system.
After installing the SIM card in the phone, you will need to configure the parameters of the Internet access point. Many mobile operators provide an automatic configuration service. If you find it difficult to adjust these parameters, contact the support service of your service provider.
What should I know about installing the phone as a GPRS modem under Windows?
When connecting via COM, a data cable or infrared port (IrDA) will be required in the Add New Modem wizard to specify the path to the modem-scripts file for your phone. If you do not have such a file, then in any search engine, type the phrase: “modem-scripts model_of your_lephone download” and download the required file using the search results. After installing the modem, record in the initialization line the data provided by your service provider. After these simple actions, the modem setup can be considered complete. Further, all actions on Internet access are identical to those for dial-up communication.
If you are unhappy (happy?) With the USB data cable owner, be prepared for the fact that most USB data cables communicate with the phone using the same COM serial port (USB-to-USB chip is installed in these USB data cables Com). The consequence of this circumstance is the need to install a driver for interfacing with a 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 pleasant way to use the GPRS modem of a cell phone is via Bluetooth. If your computer has a Bluetooth adapter, the setting will be to establish a connection between the computer and the phone, prescribing the PIN for communication and, in some cases, installing the modem-scripts file and prescribing the initialization string for the modem.
In that case, if you buy an external USB Bluetooth, be careful - for some models in the kit there are drivers with reduced functionality (the full version will cost extra money). It may be the best way to take USB Bluetooth without drivers in the kit, if something like this is written on the box: "To install the device, no additional drivers are required, 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, improved speed of communication. 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 of knowledge for practical application.
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
Source: https://habr.com/ru/post/41279/
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