Cell phones with GPRS. What can you expect? GPRS - the technology of the future
General Packet Radio Services technology.
Answering the question of what GPRS is and why it is needed, let us dwell on some aspects of the operation of GSM networks. We will not go into unnecessary technical details and will try to tell everything clearly.
1. How does GPRS work?
With a normal connection, both for conversation and for data transmission, a GSM subscriber is allocated a radio channel (more precisely, part of a radio channel) with a throughput of 9.6 Kbit/s. Such low speed seriously limits the possibilities of using GSM networks, for example, this applies to working with the Internet. (For comparison: when connecting to the Internet using a modem, the speed of information exchange can ideally reach 52 Kbps.) But when the GSM standard was developed, the need for data transmission was small, and they did not concentrate on solving the problem.
All existing difficulties associated with high-speed information exchange will disappear with the advent of third generation networks (3G). However, 3G is tomorrow ( approx. ed.: this article was written in 2006), and data needs to be transmitted today in networks that have become widespread, GSM. GPRS technology allows you to modify communications at minimal cost (although we are still talking about millions of dollars).
The operating principle of GPRS is based on the fact that the radio channel is divided into intervals (timeslots, we will call them slots). At any given time, some slots remain free, which means they can be used for data transmission. This opportunity is exploited by GPRS. A regular GSM phone always uses one slot, while GPRS devices use several at once, which significantly speeds up data transfer. The throughput of a single slot can be from 9.5 to 21.4 Kbps depending on the encoding scheme. The theoretical speed limit in GPRS is 171.2 Kbps. Based on the speed provided (the number of simultaneously occupied slots), all GPRS devices are divided into 12 classes (MultiSlot Class). First generation devices are capable of exchanging information at speeds of up to 40.3 Kbit/s.
Handsets are also classified according to another criterion - the order in which they work with data and voice (GPRS Class). Class A devices allow you to simultaneously transmit information and conduct a conversation. Class B also works in both voice and data modes, but does not allow doing this at the same time (mobile phones of this class are currently entering the market). Class C supports either voice or data.
GPRS places increased demands on the cellular network. For data transmission, resources not occupied by conversations are used. Voice traffic has priority, so if the network is congested, GPRS does not work. Accordingly, the network reserves can be judged by the data transfer speed.
The PC Magazine / RE test laboratory examined the new GPRS data services provided by the Beeline GSM network.
In theory, as stated above, GPRS provides data rates of up to 171.2 Kbps (8 channels of 21.4 Kbps per channel, using the CS4 encoding scheme). In practice, the speed is, of course, less; when using the CS2 encoding scheme implemented in existing terminals, the data transfer rate in one channel is 13.4 Kbit / s, while existing phones can only occupy three or four channels for receiving data (plus one - for transmission).
One of the problems that has significantly delayed the deployment of GPRS networks is the insufficient number of GPRS phones. When developing complete devices, designers were faced with the problem of increased energy consumption; Since the terminal operates with several channels, the transmitter power must be greater, which means more consumption. Despite the fact that the GPRS architecture provides for the possibility of solving this problem (for example, the terminal does not waste energy scanning the airwaves over a given frequency range, monitoring only the signaling channels through which information is transmitted, on which channels this particular terminal should expect data), the problem nutrition turned out to be very serious. Today it has been more or less resolved, but relatively mass production of GPRS phones is expected only in the fall. At the time of testing, there was only one phone on sale - the Motorola T260 (maximum speed 40.2 kbit/s).
Exploring GPRS services in the Beeline GSM network (while the network is in trial operation mode). First, it was planned to evaluate the quality of services based on a set of special scenarios simulating the actions of the average cellular Internet user (viewing email, Web, working with ICQ, FTP, etc.), when working with a laptop and different models of hand-held PCs (Psion netBook, Palm IIIxe and HP Jornada 548). During the research, no noticeable problems were identified when setting up GPRS connections for hand-held PCs and laptops, at least there are no more of them than when working with a regular cell phone. Everything is as always - “profiles” of the modem and “connection” are created and information provided by the operator is entered into them (IP addresses of DNS servers and “quality of service” management parameters). To connect to the GPRS network, you need to “call”, using standard system tools, to the “pseudo-phone” number * 99 #.
So far, any quantitative assessments do not make sense. The nominal communication speed in the BeeLine GSM network, according to company representatives, is 15-20 Kbps. Practice has shown that this is the peak speed; as a rule, in reality it is much less. In the Beeline GSM network today, voice traffic has a higher priority than GPRS services, and therefore the “average communication speed” parameter is small, which indicates the quality of communication; the range of values is too large. In general, Web pages load at approximately the same speed as when working with the GSM network, however, from the user’s point of view, this happens somewhat differently - if in the GSM network the page is slowly but surely “pumped”, then when working with GPRS , as a rule, there is a pause (speed 3-4 bytes/s), then a “peak” (15-20 kbit/s), the “pivsite” is loaded, then a pause again. As a result, the process takes about the same time as when working with GSM (we measured the “loading” time of the www.pcmag.ru page, taking some measures to compensate for the influence of graphics posted on other Web sites).
It is necessary to note the strange behavior of the network when working with FTP servers - if the test file is more than 1 KB in length, then the chances of copying are sharply reduced. In this case, an attempt to “download” a file using the http protocol is certainly successful. An almost similar picture is observed when working with e-mail (mails larger than 1 KB are transmitted quickly, while larger ones “freeze”). What explains this effect is unclear; It is quite possible that these are manifestations of the “exploratory” nature of the GPRS network. After the start of commercial operation, this problem can be studied in more detail.
From a user's point of view, there are few preferences in GPRS. First, the paid pause (20-60 s) disappears when connecting to the traditional “cellular Internet” (currently the user registers on the network). “Instant” connection makes work much more comfortable, and a simple calculation shows that by connecting to the cellular Internet twice a day (say, checking email, watching news, etc.), you can save 20-60 minutes per month. airtime. Another advantage is the principle of “per-megabyte” payment, which eliminates the dependence on a factor not controlled by the user - time.
It is too early to draw final conclusions, since the main thing is unknown - prices (during the trial period, until September 20, GPRS services are provided free of charge). However, at first glance the technology looks promising.
2. An inside look at GPRS technology.
One of the significant disadvantages of GSM cellular networks today is the low data transfer speed (maximum 9.6 kbit/s). And the organization of this process itself is far from perfect - one voice channel is allocated to the subscriber for data transmission, and billing is carried out based on the connection time (and at tariffs that differ little from voice ones).
GPRS (General Packet Radio Service) was developed for high-speed data transmission via existing GSM networks. It should be noted that in addition to increasing the speed (the maximum is 171.2 Kbps, but more on that below), the new system assumes a different payment scheme for data transfer services - when using GPRS, calculations will be made in proportion to the amount of information transferred, and not the time spent online. In addition, the introduction of GPRS will contribute to a more economical and rational distribution of radio frequency resources: without going into too much technical detail, we can say that data “packets” are supposed to be transmitted simultaneously over many channels (it is in the simultaneous use of several channels that the speed gain lies) in pauses between speech transmissions. And only during pauses - voice traffic has unconditional priority over data, so the speed of information transfer is determined not only by the capabilities of the network and subscriber equipment, but also by the network load. I would like to emphasize that in GPRS not a single channel is dedicated entirely to data transmission - and this is the main qualitative difference between the new technology and those used today. Just imagine - you can always have a green ICQ daisy on your laptop without loading the network, and pay in proportion to the volume of messages received and sent.
Of course, the GPRS developers made every effort to ensure that installing a new system “on top” of existing GSM networks would be as less burdensome (and costly, which is important) for operators as possible. Let's take a closer look at what new blocks and connections appear in the overall architecture of the GSM cellular communication system with the introduction of GPRS, and then discuss user equipment capable of working with high-speed packet data transfer.
2.1 GPRS from within.
Modification of the GSM network to provide high-speed GPRS data services can be divided into two forms - software and hardware. If we talk about software, it requires either replacement or updating almost everywhere - from HLR-VLR registries to BTS base stations. In particular, a multi-user access mode to temporary frames of GSM channels is being introduced, and in HLR, for example, a new parameter Mobile Station Multislot Capability appears (the number of channels that a subscriber’s mobile phone can simultaneously work with, but more on that below).
Rice. 1 Block diagram of the GPRS network.
The core of the GPRS system (GPRS Core Network) consists (Fig. 3.1) of two main blocks - SGSN (Serving GPRS Support Node - GPRS support node) and GGPRS (Gateway GPRS Support Node - GPRS gateway node). Let's look at their functions in more detail.
The SGSN is, roughly speaking, the brain of the system in question. In some ways, SGSN can be called an analogue of MSC - a GSM network switch. Just like MSC and SGSN, there may be more than one in the system - in this case, each node is responsible for its own section of the network. For example, SGSN manufactured by Motorola has the following characteristics: each node supports transmission of up to 2000 packets per second, simultaneously controls up to 10,000 online users. In total, the system can have up to 18 Motorola SGSNs.
The purpose of GGSN can be understood from its name - roughly speaking, it is a gateway between the cellular network (more precisely, its part for transmitting GPRS data) and external information highways (Internet, corporate intranet networks, other GPRS systems, etc.). The main task of the GGSN is thus to route data going to and from the subscriber through the SGSN. Secondary functions of GGSN are data addressing, dynamic issuance of IP addresses, as well as tracking information about external networks and its own subscribers (including service tariffs).
Note that the GPRS system has good scalability - when new subscribers appear, the operator can increase the number of SGSNs, and when the total traffic escalates, add new GGSNs to the system. Within the core of the GPRS system (between SGSN and GGSN), data is transmitted using a special GTP tunnel protocol (GPRS Tunneling Protocol).
Another component of the GPRS system is the PCU (Packet Control Unit). The PCU interfaces with the BSC base station controller and is responsible for routing data traffic directly from the BSC to the SGSN.
In the future (when the system is oriented towards the mobile Internet), it is possible to add a special node - IGSN (Internet GPRS Support Node - Internet support node).
OMC-R / G (Operation and Maintenance Center - Radio / GSN - control and maintenance center for the radio / GPRS node: not shown in the figure) is responsible for managing and monitoring the GPRS system. This is the so-called interface between the system and its operating personnel.
Before starting to work with GPRS, the mobile station, as in the usual case of voice transmission, must register in the system. As already mentioned, the registration (or, more precisely, the “attachment” to the network) of users is handled by the SGSN. If all procedures are successfully completed (checking the availability of the requested service and copying the necessary user data from the HLR to the SGSN), the subscriber is issued a P-TMSI (Packet Temporary Mobile Subscriber Identity) similar to the TMSI that is assigned to the mobile telephone for voice transmission (by the way, if the subscriber terminal belongs to class A, then both TMSI and P-TMSI are allocated to it during registration).
To quickly route information to a mobile subscriber, the GPRS system needs data about its location relative to the network, and with greater accuracy than in the case of voice traffic transmission (let me remind you that HLR and VLR store the number of the Location Area (LA) in which the subscriber is located). But imagine how the service traffic on the cellular network and the energy consumption of a mobile device will increase if the phone informs the system every time it moves from one cell to another! To find a compromise between the volume of signaling traffic in the GPRS network and the need to know the subscriber’s location with high accuracy, it is customary to divide terminals into three classes:
· IDLE (inoperative). The phone is switched off or out of network coverage. Obviously, the system does not track the movement of such subscribers.
· STANDBY (standby mode). The device is registered (attached) in the GPRS system, but has not been transmitting data for a long time (determined by a special timer). The location of STANDBY subscribers is known up to RA (Routing Area). RA is smaller than LA (each LA is divided into several RAs, but, however, RA is larger than a cell and consists of several unit cells).
· READY (readiness). The subscriber terminal is registered in the system and is in active operation. The coordinates of phones in READY mode are known to the system (or, more precisely, SGSN) accurate to the cell. According to this ideology, terminals in STANDBY mode, when moving from one RA to another, send a special signal to the SGSN to change the routing area (routing area update request). If the new and old RA are controlled by the same SGSN, then changing the RA only leads to an adjustment of the entry in the SGSN. If the subscriber moves into the coverage area of the new SGSN, then the new SGSN requests information about the user from the old one, and the MSC, VLR, HLR and GGSN are notified of the change in SGSN. When a GPRS phone moves to another LA, the SGSN sends a message to the corresponding VLR to change the subscriber's location record.
The situation with data routing in the case of roaming GPRS subscriber is interesting. In this case, two options are possible, or, more appropriately, scenarios. SGSN in both cases is used as a guest (VSGSN - Visited SGSN), but GGSN can be used either as a guest (VGGSN - Visited GGSN) or home (HGGSN - Home GGSN). In the latter case, a GPRS backbone (InterPLMN GPRS BackBone - GPRS line between different mobile networks) must exist between the home and guest operators to transmit traffic between the HGGSN and the mobile subscriber. In addition, there is a need for a BG (Border Gateway) on both sides in order to ensure the protection of networks from external attacks.
It is worth noting such an important parameter as Qo (Quality of Service). Obviously, real-time videoconferencing and emailing have different requirements, such as delays in the path of data packets. Therefore, in GPRS there are several Qo classes, which are divided according to the following criteria:
· Necessary priority (there is high, medium and low priority data);
· Reliability (divided into three classes according to the number of possible errors of various kinds, lost packets, etc.);
· Delays (information delays outside the GPRS network are not taken into account);
· Quantitative characteristics (peak and average speed);
The Qo class is selected individually for each new data transfer session.
In addition to Qo, the characteristics of a data transfer session include the protocol type (PDP type - Packet Data Protocol type), the PDP address issued to the mobile station (address issuance can be both static and dynamic), as well as the GGSN address with which the work is in progress. The session “profile” (in English literature the designation “PDP context” is accepted) is recorded in the phone, as well as in the SGSN and GGSN serving it. Several data transfer profiles can be supported simultaneously for each user.
Generally speaking, packet data transfer provides two modes of “connections”:
1. PTP (Point-To-Point);
2. PTM (Point-To-Multipoint).
The PTM broadcast mode is in turn divided into two classes:
1. PTM-M (PTM-Multicast) - transfer of necessary information to all users located in a certain geographical area;
2. PTM-G (PTM-Group Call) - data is sent to a specific group of users.
Support for multipoint PTM transmission mode is expected in future GPRS specifications.
Therefore, the main characteristics of the GPRS protocol are the efficient use of radio and network resources, as well as completely transparent support for the IP protocol. GPRS optimizes the use of network and radio resources. The GPRS protocol uses radio resources only in cases where data is actually required to be received or transmitted. Using packet technology, this protocol allows applications to use network resources only when user applications have data to transmit over the network. Thus, the protocol is adapted to the uneven nature of user application traffic.
Another important characteristic of GPRS is that it provides immediate connections and high throughput. Applications based on standard data transfer protocols such as IP and X.25 are supported. To support data applications, the GPRS protocol uses several new network nodes, in addition to the network nodes used in GSM PLMN. These nodes are responsible for routing traffic and implementing other functions for exchanging with external packet switching networks, searching for subscribers, selecting cells, roaming and many other functions necessary to ensure the operation of a cellular network. In addition, GPRS uses the GSM SMS and GSM MM protocols (the latter is called GMM in GPRS).
2.2 GPRS external subscriber devices.
Let's now talk about GPRS client equipment. Unfortunately or fortunately, to work with the packet data transmission system you need to have a special phone compatible with GPRS. More strictly speaking, GPRS terminals are divided into three classes:
1. Class A devices are capable of simultaneously working with both voice and data transmission (technically speaking, they have the ability to operate in both circuit switched and packet switched modes). I emphasize — we are talking about simultaneous work in different modes);
2. Class B devices can carry out either voice or data transmission, but not simultaneously;
3. Class C devices only support data transmission and cannot be used for voice communication. As a rule, these are various kinds of computer boards to provide wireless access to data.
It should be noted that the maximum data transfer rate is determined, first of all, by the number of channels with which the subscriber terminal can simultaneously operate. One channel provides data transmission at speeds up to 13.4 Kbps.
The French company SAGEM was one of the first manufacturers to introduce GPRS-compatible phones. The Sagem MC-850 model, which was presented at the Geneva TELECOM-99 exhibition, belongs to class B and has one data transmission channel and three for reception, and the slightly more modern Sagem MW-959, presented to the public at CEBIT-2000, already includes four channels for incoming traffic (there is still one channel left for transmission, and the device class has not changed). Thus, the maximum data reception speed using the Sagem MW-959 phone is 53.6 Kbps, and the transmission speed is 13.4 Kbps.
Conclusion. This year, 2002, an avalanche-like, so to speak, introduction of GPRS throughout the world is expected. The next step from GSM to third-generation networks UMTS (Universal Mobile Telephone System) is EDGE technology (Enhanced Data Rates for GSM Evolution - loosely translated as “data transfer at increased speed”), which allows information to be transferred at speeds of up to 384 Kbps over eight GSM channels (48 Kbit/s per channel). To implement EDGE “over GPRS,” operators will need to replace the equipment of BTS base stations, and users will need to purchase telephones that support EDGE. Although at the moment it is personally difficult for me to imagine what a GSM cellular network subscriber should do so that he does not have enough speed of 170 Kbps offered by GPRS.
2.2.1 What does GPRS technology give to a subscriber?
GPRS will allow the introduction of fundamentally new services that were not previously available. First of all, this is mobile access to Internet resources with consumer-satisfying speed, instant connection and a very favorable tariff system. For example, when viewing a WEB page using the GPRS system, we can study the content as much as we need, since we pay only for the received information and do not pay for the time spent on the Internet (by not transmitting data, we do not occupy network channels). With the introduction of time-based payment on fixed telephone lines, tariffs for Internet access from a mobile GPRS phone will be even more competitive.
GPRS technology will allow you to quickly transmit and receive large amounts of data, video images, MP3 music files and other multimedia information.
For those subscribers who have already appreciated the convenience of using phones with a WAP browser, the introduction of GPRS technology means almost instant loading of WAP pages on the phone screen and a more favorable tariff system.
For corporate users, the GPRS system can serve as an excellent tool for providing employees with secure and fast access to corporate enterprise networks, mail and information servers, and remote databases. At the same time, it will be possible to gain access to corporate networks even if the subscriber is in the network of another GSM operator with whom GPRS roaming is organized.
GPRS technology can be used in telemetry systems: the device can be connected all the time without occupying a separate channel. Such a service may be required by bank security services to connect ATMs in other areas, including industrial ones.
3. Trends in the development of demand for GPRS. Prospects for the development of services.
Having described the advantages of GPRS, it hardly needs proof to state that while a number of GSM operators see GPRS as merely a stepping stone to 3G systems, others - especially those who do not intend to apply for 3G licenses and have no hope of obtaining such licenses - are looking at GPRS as a long-term solution to meet the predicted explosion in wireless data communications, comparable to what can be achieved through flagship implementation. However, for those who intend to implement 3G systems, the additional equipment required to support GPRS will be a good basis for supporting data traffic in W-CDMA systems.
The development of GPRS infrastructure, which is actively pursued by Alcatel, Ericsson, Lucent, Motorola, Nokia, Nortel and Siemens, is moving forward by leaps and bounds. Tests of GPRS systems carried out jointly with operators enabled the first GPRS data call to be made on a live GSM network back in November 1999. Since then, although GPRS development received initial impetus from the major European GSM operators, more and more operators from other regions, especially Asia-Pacific, have reported testing GPRS systems.
The delivery of subscriber terminals (i.e. GPRS phones), as in the case of WAP, was late compared to the development of infrastructure. Successful launches of GPRS networks into commercial operation will be hindered due to the lack of suitable phones in mass quantities. As of early March 2000, only a few cell phone manufacturers had demonstrated prototypes of GPRS equipment, and none of them could give exact dates for their commercial production.
After the mass appearance of various models of GPRS phones on the market, GPRS services will gradually be reoriented towards the mass consumer, and the development of GPRS will follow a combined scenario that takes into account the interests of both corporate clients and the mass consumer, with a development trend towards the requests of the latter.
Many users do not have a very clear idea of what GPRS is. This abbreviation stands for "public packet radio communications". This is an add-on to mobile communication technology that transmits data. With this method of providing information, the radio channel used is occupied only directly during the data transmission process. In this regard, high efficiency of its use is achieved. The presence of GPRS allows the device to exchange information with other devices within the GSM network, as well as with external networks, access the Internet and connect to relevant services: news channels, Internet pages, etc.
What is the difference between WAP and GPRS
The difference primarily concerns payment. When you use the Internet, connecting to WAP, using a regular connection (CSD), your phone is busy at that time. At the same time, you pay for this connection almost the same as for a regular conversation on a mobile phone. While GPRS technology allows you to transfer data through parallel channels that do not interfere with normal communications. Payment for using GPRS Internet involves charging based on the volume of information exchanged, and not on the amount of time spent on the network. What is GPRS traffic? These are files transferred when using the Internet. For example, opening any Internet page already involves downloading text files and page design. Paying for GPRS Internet is more profitable than for calls: about 10-20 cents per megabyte of data. Thus, it becomes clear what GPRS is in a phone - this means that your mobile phone can always be in GPRS connection mode. The connection does not interfere with incoming and outgoing calls, and if you do not download anything specifically, then the money does not leave your account.
What is GPRS service
Some operators, for example Megafon, Beeline, MTS, offer a GPRS Internet service, which allows you to access the Internet and use various kinds of Internet services in the absence of a computer or landline phone.
Thanks to this service, you can use the Internet in any situation. For example, you can check your email, use the corporate network, you can coordinate the actions of employees via the Internet, regardless of where you are. You will be able to download content, use ICQ or other means of communication. It’s also convenient that you can use your phone instead of a modem
Before connecting to this service, make sure that your phone or smartphone supports GPRS.
What does it mean to use a GPRS phone as a modem?
By connecting a GPRS phone to a regular computer or laptop, you can get access to the Internet. The speed is comparable to a conventional modem. However, the maximum speed, which is 115 Kbps, is difficult to achieve in practice. The reason for this is the structure of GPRS itself. The maximum speed will be achievable provided that there is sufficient traffic from the operator with the Internet, as well as at the base station to which your cell phone is connected, if there are free channels. The opportunity to achieve maximum speed occurs at night, when the cellular operator's networks are least loaded.
GPRS is a technology for packet data transmission over a radio channel (General Packet Radio Service) in GSM networks. The main feature of GPRS is that the information (received/transmitted) is divided into small data packets and then transmitted simultaneously over several communication channels. Thanks to this, the maximum possible access speed using GPRS technology is 170 Kbps. In this case, the voice channel is busy only during data transmission, and not constantly, as with other forms of network access.
Subscribers of which operators can use this technology?
At the moment, only one operator has launched the GPRS service into commercial operation - Bee Line. This happened on April 1, 2002, until that moment all its subscribers (except Bee Plus) could use this service in test mode for free.
Are MTS or Megafon going to introduce GPRS?
Recently, MTS announced that their GPRS network is ready. But she is in no hurry to put it into commercial operation. This is due to the fact that, according to them, the market is not yet ripe for this service. Demand creates supply, but there is no demand yet (GPRS phones are too expensive). In addition, MTS, along with the launch of GPRS into commercial operation, intends to provide various services based on the use of this technology.
In any case, MTS will introduce GPRS in the near future. Currently, subscribers of this company can use this service for free. To do this, you must obtain permission and all necessary information from the operator.
As for MegaFon, things are not going very well here. They do not have a GPRS network, and it is difficult to say when it will appear. MegaFon is now busy with more important matters, for example, obtaining a license to broadcast on the 900 MHz frequency in the Moscow region.
What is needed to use GPRS?
To do this, you need to activate the GPRS service from your operator. This can be done by calling a special number (you can find it in the operator’s help desk). Naturally, you need to purchase a phone that supports GPRS. That's basically it. The purchase of additional accessories depends on what devices you will use the GPRS phone with. You may not have to buy anything extra and the IrDA port on your phone and laptop will suffice. Sometimes phones come with a cable for connecting to a PC (for example, Siemens ME45/S45). Otherwise you will have to buy it separately.
Motorola T260
Can I use GPRS via Bluetooth?
Yes, sure. If your phone supports GPRS and is equipped with Bluetooth, you can use it as an external modem with any device that has a Bluetooth module. For example, if we are talking about a laptop, then you need to purchase a Bluetooth PC Card and enjoy working with the Internet without unnecessary wires.
What devices can be used to access the Internet using a GPRS connection?
There are no restrictions at all. From absolutely any device, from an old Palm to a desktop computer. The fact is that the device itself should not have GPRS support.
To work via a GPRS connection, you need to create a regular modem. If we are talking about a PDA, then it is necessary to create an external modem that works via IrDA. Since all the necessary work with data is done by the modem built into your phone.
Can I use a GPRS modem on a desktop PC?
Yes it is possible. To do this, you need to create a new modem using a special GPRS modem driver. Usually the necessary software is on the disk that came with the phone. If this disk is not available, you can find the necessary software on the Internet.
After this, you need to configure the modem and you're done!
What is the maximum data transfer speed via GPRS connection?
In the future, the speed will be 170 Kbit/sec. Currently this speed is 40-45 Kbps. This is due to the fact that most GPRS phones currently produced have 3 timeslots for receiving and 1 timeslot for transmitting information.
Operators say they will increase the capacity of their networks as soon as phones with more timeslots become available. This is not about whether such phones will appear at all (they already exist), but about when their price will become affordable to a large number of users.
What is the average data transfer speed via GPRS connection?
It is incorrect to talk about average speed with GPRS. Since information is either transmitted or not. That is, the speed is from 0 to 40-45 Kbps. But the packet transmission speed depends on the network load at one time or another. If you are in an old, overloaded cell, the speed will be minimal. And if you are in a new cell, which is also completely unloaded, the speed will always be maximum.
Is it possible to talk on a cell phone during a GPRS session?
Yes it is possible. The fact that during a GPRS access session you do not constantly occupy the voice channel is the main advantage of this technology. The channel is busy only during data transmission/reception. If you receive a call, the session will be interrupted and will resume automatically when the call ends.
It is also worth noting that there are three types of GPRS modems - A, B, C.
C-class are usually GPRS modems; they are not supposed to be used for conversation, they are created only for data transfer. Most often these are PC-GPRS cards for laptops.
B-class are devices capable of working as regular phones, as well as a GPRS modem. At the moment, all phones on sale are A-class. That is, in them you can either transmit/receive data, or talk alternately.
A-class is a new generation of devices, they can simultaneously transmit/receive data and talk. There are no such devices for sale on the market yet, at least not officially in Russia.
Can I receive and send SMS during a GPRS session?
Yes it is possible. Here the situation is the same as with the ability to receive calls during a session. As soon as there is a pause in data reception/transmission, you will receive SMS messages. In this case, the connection will not be interrupted, but will only pause for a few seconds.
What are the advantages of GPRS compared to Dial-Up?
The advantage is that during a GPRS session you only pay for the information received/transmitted. And with a Dial-Up connection, you pay for the session time. For example, if you use Internet messengers, then it is not profitable for you to pay for the time spent on the Internet. In this situation, it is much more efficient to pay for traffic, which will amount to a few kilobytes.
Can the GPRS connection suddenly be interrupted?
No. At least, based on our personal experience, we can safely say this. If you do not move between cells during a session, the connection will be absolutely stable. It’s more likely that your phone’s battery will run out than the connection will be interrupted.
Can I use GPRS, for example, while driving in a car?
Yes it is possible. Officially, the operator does not guarantee this possibility, but as our practice has shown, it is quite possible.
It is worth considering that problems may arise when moving between base stations, as you may end up in an overloaded cell, resulting in a GPRS session failure. But, as we already said, we didn’t have that. Even when moving around the center of Moscow, where the number of base stations is very large and their congestion is obvious, the connection was stable.
How are GPRS services paid?
Currently, only Bee Line has launched the GPRS service into commercial operation. So the question of paying for GPRS may only arise for subscribers of this operator.
Bee Line has chosen the following tariff option: all received/transferred MB are paid for. One megabyte is charged at $0.30 including all taxes.
You will receive a regular invoice showing the amount of $ you spent using your GPRS connection. It is added to voice traffic, and you can pay this bill, as usual, in any place convenient for you. You don't have to pay for GPRS separately.
Under what conditions does the cellular network provide GPRS services?
Currently, GPRS services are provided on a secondary basis. This means that the operator’s priority is voice traffic. If a situation arises in which the cell is overloaded with users, the equipment will automatically limit the possibility of GPRS access. As soon as the number of users in one particular cell is reduced, again, the equipment will automatically be configured to provide GPRS services in full. This is done in order not to limit the provision of voice traffic to subscribers.
Can I use WAP over GPRS?
Yes it is possible. All GPRS phones currently sold provide this feature. It is worth considering that with the Bee Line operator the ability to use WAP via GPRS is paid separately. You pay $3 and use WAP for a month without paying for the amount of information transmitted/received. This form of payment is convenient for subscribers who do not plan to use GPRS for other purposes.
Are operators planning to increase connection speeds via GPRS?
Yes, it is planned. As soon as there are phones capable of running at higher speeds. Operators will be ready for this. The main problem is that increasing the number of timeslots will lead to greater congestion of the base stations. It will be necessary to increase the capacity of the entire network. For example, MTS at the time of writing this material had 3.5 million subscribers, and the network capacity is about 5 million subscribers. This means that this operator has partially prepared for a possible increase in timeslots.
What determines the connection speed via GPRS?
The data transfer speed in a GPRS network depends on several important circumstances. The first and, perhaps, most important thing is network congestion. Or a specific cell at a specific moment. Also, the speed may be affected by old equipment and software installed on the base station. Secondly, this is the number of timeslots allocated for GPRS operation.
Is there GPRS roaming?
Yes, such a concept appeared quite recently. Currently, Bee Line subscribers can use GPRS services from some European operators that support this technology. And absolutely free, for now...
Ericsson R520
What is the best GPRS phone at the moment?
As practice has shown, all devices work approximately the same. The only significant difference is the setup procedure. In some models it is too complicated.
What should I do if I activated the GPRS data service, but it doesn’t work for me?
Contact your operator's help desk. After the Bee Line company introduced GPRS services into commercial operation, they began to pay a lot of attention to GPRS problems.
But first of all, check that all the settings are correct on the phone itself and on the device through which you want to access the network.
Where in Moscow and the region can I use GPRS access to the Internet?
The entire territory of Moscow is covered by a GPRS network. As for the Moscow region and the territory of Russia, for each specific district or city you need to clarify the data with the operator. I would like to note that almost the entire Moscow region is covered by the GPRS network of both Bee Line and MTS.
My phone has a function for sending SMS via GPRS. Can I use it, and if so, how much does it cost?
Yes it is possible. SMS will be charged as usual, according to the tariff plan you have chosen.
How long can a phone work with GPRS on one battery charge?
This depends on the battery capacity of your phone. It is worth considering that during a GPRS session, energy is not consumed constantly and at different rates. This is due to the fact that energy consumption occurs only during data reception/transmission. Moreover, it is of great importance how much information is received/transmitted. If we are talking about an Internet pager, then the phone will work for a very long time, and if you constantly download large files, the battery will drain quickly.
On average, operating time can be determined by the number of declared hours of talk time.
I heard that radiation from GPRS is harmful to health, is that true?
The emission during a GPRS session is identical to the emission during a normal conversation. The only exception is the power of this radiation. If the phone uses three timeslots for data transmission, and data is transmitted through all of them, the corresponding radiation strength in this case is three times greater than in normal operation. Therefore, we strongly recommend that you keep your phone as far as possible from your head and other vital organs during a GPRS session. On the other hand, no one has yet been able to document that radiation from a cell phone can lead to disease.
GPRS (General Packet Radio Service) – general packet radio communications. GPRS uses the shared physical resource of the GSM air interface in conjunction with circuit switching. GPRS can be considered as a technology superimposed on the GSM network. This allows the same physical environment in cells to be used for both circuit-switched voice and packet-switched data. GPRS resources can be allocated for data transmission dynamically during periods when there is no circuit-switched information transmission session.
The same physical channels are provided for GPRS, but their efficiency is much greater compared to traditional circuit-switched GSM, since multiple GPRS users can use the same timeslot. This allows for increased channel utilization. In addition, GPRS uses resources only during the period of data transmission and reception.
GPRS network architecture
The figure below shows the structure of the GPRS system. Since GPRS is a new GSM network technology, it uses the existing GSM infrastructure with some modifications. The GPRS system solution was developed in such a way that GPRS could be implemented quickly and cost-effectively on networks.
Two new nodes appear in the GSM network: the Serving GPRS Support Node (SGSN) and the Gateway GPRS Support Node (GGSN). These two nodes can be physically implemented on the same hardware. Flexible implementation of GPRS is possible, first, for example, the implementation of a combined GPRS node, which is a combination of SGSN and GGSN nodes. In the next stage, they can be divided into SGSNs and GGSNs.
SSGN interfaces are called G interfaces (Gb, Gr, etc.), all of which are defined by ETSI standards. Standardization makes it possible to connect equipment from different manufacturers. The interfaces to UMTS (3G) network nodes are called I interfaces (Iu, Iur, etc.).
GPRS terminals
There are three classes of MS that can work with GPRS.
Class A: Class A MS can be simultaneously registered in the GPRS network and in the GSM network. A Class A MS can also simultaneously transmit/receive voice and packet-switched data.
Class B: A Class B MS can simultaneously register in the GPRS network and in the GSM network, but at any given time it can receive/transmit information from either circuit-switched services or packet-switched services.
Class C: Class C MS can be registered at one time either in the GSM network or in the GPRS network.
BSS Base Station System
The GPRS system interacts with the MS over the radio interface by transmitting and receiving radio signals through the BSS system. The BSS controls the transmission and reception of radio signals for all types of messages: voice and data, transmitted in circuit switched and packet switched modes. When implementing GPRS, additional software is required for BTS base stations.
BSS is used to separate circuit-switched and packet-switched data, since only circuit-switched messages are sent to the MSC. Packets are forwarded to new GPRS packet switching nodes.
CSS circuit switching system
CSS is a traditional SS system of the GSM network, which includes the nodes already discussed earlier. When implementing GPRS, it is necessary to upgrade the MSC software, which allows you to perform combined GSM/GPRS procedures, for example, a combined MS connection procedure (Attach): IMSI/GPRS.
The introduction of GPRS has no impact on the GMSC.
HLR is a database that contains all subscriber data, including those related to GPRS services. Thus, the HLR stores data for both the circuit switching service and the packet switching service. This information includes, for example, permission/denial of the subscriber to use GPRS services, the text name of the access point (Access Point Name - APN) of the Internet Service Provider (ISP), as well as an indication of whether a fixed IP address.
GPRS information is stored in the HLR as a subscription to the PDP (Packet Data Protocol) context. HLR can store up to 5 PDP contexts per subscriber. Information stored in the HLR is accessed from the SGSN. When roaming, access to information may occur in an HLR that is not associated with its own SGSN.
Packet Switching System PSS
PSS is a new system designed specifically for GPRS. This system is based on the Internet Protocol (IP). It includes new packet switching nodes, generally known as GSN (GPRS Support Node). There are currently two types of GPRS nodes: Serving GPRS Support Node (SGSN) and Gateway GPRS Support Node (GGSN). SGSN interfaces connect it to standard GSM network nodes, such as MSC/BSC, and GGSN interfaces connect this node to external packet data networks, such as the Internet or corporate Internet.
The GPRS support nodes are SGSN and GGSN, each of which performs specific functions within the GPRS network. These specific individual functions are described below.
The SGSN is located in the GPRS network as shown in the figure below. This node communicates with BSC, MSC/VLR, SMS-G and HLR. This node is connected to the internal transmission network.
SGSN serves all GPRS subscribers physically located within the SGSN service area. The SGSN performs functions in GPRS similar to those performed by the MSC in the GSM network. That is, this node controls the functions of connecting, disconnecting MS, updating location information, etc. GPRS subscribers can be served by any SGSN node in the network depending on their location.
As part of the GPRS network, the SGSN node performs the following functions. MS Mobility Management (MM – Mobility Management). MM procedures supported over this interface are IMSI connection for both GPRS and circuit switched calls, location zone update, combined location zone update for GSM and GPRS, paging signaling.
MM procedures allow the network to monitor moving subscribers. MM allows an MS to move from one cell to another, to move from one SGSN routing area to another, to move between SGSN nodes within a GPRS network.
The concept of Location Area is not used in GPRS. The analogue of this concept in GPRS is the Routing Area - RA. Both of these terms mean location area, but LA is for GSM and RA is for GPRS. RA consists of several cells and can be less than or equal to LA. In the first implementation, RA was equivalent to LA.
Creating a communication session with packet transmission in GPRS is called PDP context activation.
SM procedures include activating a packet data protocol (PDP) context, deactivating that context, and modifying it.
The PDP context is used to establish and release a virtual data link between the terminal connected to the MS and the GGSN.
When the SGSN receives a PDP context activation request message, it requests the access permission control function. This feature limits the number of registered users within a single SGSN and monitors quality within each zone. The SGSN then checks whether the subscriber is allowed to access a specific ISP (Internet Service Provider) or corporate data network (by checking the list of allowed APNs).
Routing functions are integrated into both nodes: SGSN and GGSN. These are standard IP router functions and additional functions for internal load balancing, both payload and management traffic. The router is thus capable of handling both general IP traffic and special GPRS protocols.
The GGSN provides an interface towards the external IP network with packet data transmission. The GGSN provides access functions for external devices such as ISP routers and RADIUS servers that provide security functions. From an external IP network perspective, the GGSN acts as a router for the IP addresses of all subscribers served by the GPRS network. Routing of packets to the desired SGSN and protocol translation are also provided by the GGSN node.
Physical channels in GPRS
To support GPRS, the cell must have circuit groups assigned to packet switched (PS) connections. The physical channels assigned to GPRS are called Packet Data Channels, or PDCHs.
If a timeslot is used to transmit packet data, then it is included in the shared resource of packet channels (PSD - Packet Switch Domain). If the timeslot is used for circuit switching, then it is included in the CSD (Circuit Switch Domain).
In a cell, PDCHs will coexist with traffic serving channels for the CS. The PCU (Packet Control Unit) is responsible for assigning PDCH channels.
The same PDCH can be shared by multiple GPRS users. The transaction for transmitting/receiving packets is called TBF - Temporary Block Flow. The MS may have two TBFs simultaneously, one of which is used in the uplink direction and the other in the downlink direction. Each TBF is identified by a number called TFI - Temporary Flow Identity.
When a TBF is assigned, one or more PDCHs are reserved for the MS. In GPHS it is possible to combine multiple PDCHs, this aggregation is called PSET and can be used by one or more MSs. The PDCH can combine several timeslots (up to 4 so far) on the same frequency. Before reserving a channel, the system must ensure that there are one or more free PDCHs in the PSD.
Logical channels in GPRS
There are over 10 types of logical channels defined in the GSM system. These channels are used to transmit different types of information. For example, the paging channel PCH is used to transmit the calling message, and the broadcast control channel BCCH transmits system information.
A new set of logical channels has been defined for GPRS. Most of them have names similar to and corresponding to the names of the channels in GSM. The presence in the abbreviated name of the logical channel of the letter “P”, meaning “Packet” and standing in front of all other letters, indicates that this is a GPRS channel. For example, the paging channel in GPRS is designated as PPCH - Packet Paging Channel.
A new logical channel of the GPRS system is the PTCCH channel (Packet Timing advance Control Channel). This is a channel for transmitting information about TA, it is necessary to adjust this parameter. In the GSM system, information related to this parameter is transmitted on the SACCH channel.
The Packet Paging Channel is a paging channel and is used only in the downlink direction to transmit the paging signal to the MS before transmitting packets. PPCH can be used to establish either a packet-switched connection or a circuit-switched connection.
The use of the PPCH channel for circuit switched mode is only possible for GPRS class A and B terminals in a network with operating mode I (NOM=1).
Packet Random Access Channel, used only in the uplink direction. PRACH is used by the MS to initiate transmission in the uplink direction for data or signaling.
Packet Access Granted Channel is used only in the downlink direction during the connection establishment phase to convey resource assignment information. Sent to the MS before packet transmission begins.
The Packet Notification Channel is used only in the downlink direction to transmit information in broadcast mode (PTM-M - Point-to-Multipoint - Multicast) to the MS group before transmitting the PTM-M packet. To monitor the PNCH channel, the DRX mode must be assigned. DRX services are not specified for GPRS phase 1.
The Packet Associated Control Channel carries signaling information during a packet transmission session for a specific MS. The signaling information includes instructions for controlling the power output of the terminal. PACCH also carries resource assignment or reassignment messages. This channel shares resources with the PDTCHs assigned to the MS. In addition, a paging message may be sent over this channel to an MS in a packet-switched connection state indicating that the MS is being called to establish a connection, for example a circuit-switched connection.
Packet Timing advance Control Channel is used only in the uplink direction for the transmission of Access Burst to estimate the time delay in the delivery of information from an MS in packet transmission mode.
Data packets are transmitted over this channel. If the system is operating in PTM-M mode, then it is temporarily assigned to one MS from the group. If the system operates in multi-slot mode, one MS can use multiple PDTCHs in parallel for one packet transmission session. All traffic channels for packet transmission are bidirectional, with a distinction being made between PDTCH/U for the uplink transmission direction, and PDTCH/D for the downlink transmission direction.
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A modern mobile phone is not just a device for voice communication, but a full-fledged communication center that provides constant access to the Internet.
For this, as a rule, GPRS technology is used, which stands for General Packet Radio Service. Using this technology, packet information is exchanged at a fairly high speed - 175 kbit per second.
If the phone is constantly connected to the GPRS service, its owner has the opportunity to access the Internet wherever there is a cellular connection, and the data exchange is not interrupted during regular calls.
How is data exchanged?
By connecting to GPRS, each user receives his own personal channel, which is used to transmit via a modem built into the telephone. The modem is configured to a dedicated GPRS communication channel and exchanges data through it.
The transfer occurs within the scope of the services of the cellular operator to which the phone’s SIM card is connected. Using GPRS technology:
— you get instant access to the Internet connection, without additional conditions - calls to the provider, etc.; 
— full Internet access is provided as easily as with a wired connection;
— you can connect to the Internet not only a smartphone, but also a laptop or;
— only real Internet access is charged, i.e. the amount of information sent or received, not the time you spent online.
How to connect GPRS on your phone?
As a rule, all mobile operators send settings for GPRS connection automatically when activating a new SIM card. Therefore, the vast majority of users do not even think about the problem of connecting to GPRS - this service works for them by default. However, in some cases you have to connect manually.
Most often, this need arises among owners of “non-standard” phone models for which operators have not provided automatic configuration. Of course, to connect to GPRS, the phone must at least meet the level of this technology and provide the ability to use it.
To connect to GPRS you need a provider that provides you with communication services. The operator's number is easy to find on its official website. After connecting with a call center employee, you need to tell him about your problem and ask him to send the settings to your mobile number. Specify in the conversation that you need Internet settings, not WAP. 
As a rule, the operator sends a package of automatic settings, and the only thing that is required of you is to agree to their installation on the phone. If this does not help, you can try, together with a call center employee, to manually enter the settings. You can reach the operator at the following numbers:
- - call number 0876 or send an empty SMS message to number 1234;
- - call 0500 or send an SMS message consisting of the number 1 to number 5049;
- - call 0880, after sending the settings you must save them using the password “1234”;
- - call 679.
For MTS, TELE2 or Beeline subscribers, it is possible to order GPRS settings using the official website by logging into your personal account. In the order form you need to indicate your phone model, your number and the operating system installed on the phone.
Typically, between a few seconds and a few minutes passes between submitting an order and receiving settings. Megafon and TELE2 post detailed instructions for connecting GPRS on their websites. For a phone with multiple SIM cards, you need to get settings separately for each card. 
The easiest way out in a situation where all the above methods have been tried and there is no result is to go to your operator’s salon and contact the manager. The GPRS setup on your phone will be done in front of you and completely free of charge, after which you will be able to use the Internet without restrictions anywhere where your operator has coverage.
