Mobile network for example in the case. How does cellular communication work?
In this article we will tell you about the history of the emergence of mobile communications.
The first radiotelephone communication system appeared in 1946 in the USA - St. Louis. Radiotelephones operated on fixed frequencies and were switched manually. In the Soviet Union, radiotelephone communications appeared in 1959 and were called the Altai system. Naturally, it was not publicly accessible, but was used as government communications and by intelligence agencies. In 1990-1994, during the collapse of the USSR, a large mass of classified developments, including the development of multi-frequency, multi-base radiotelephone communications, were exported “free” from Soviet research institutes outside the cordon. And in 1991 in the USA, and subsequently in Russian Federation a new radiotelephone standard - cellular communication NMT-450 (Sotel) has appeared. An analog signal was used. Subsequently, digital standards appeared - GSM-900 and GSM-1800.
With the progressive development of cellular communications, mobile telephones have become widely available. As a rule, a mobile telephone unit (hereinafter referred to as MTA) can operate at a distance of up to 1500 m from the base station.
As you know, each cellular device is assigned its own electronic serial number (ESN), which is encoded in the phone's microchip when the phone is manufactured. By activating the SIM card (Subscriber Identity Module) - a microchip in which the subscriber number is “stitched”, the mobile telephone device receives a mobile identification number(MIN).
The area covered by the GSM (Global System for Mobile communications) network is global system mobile communications), is divided into separate, adjacent cells (cells) - hence the name “ cellular communication”, in the center of which there are transceiver base stations. Typically, such a station has six transmitters, which are located with a 120° radiation pattern and provide uniform coverage of the area. One average modern station can simultaneously service up to 1000 channels. The area of a “honeycomb” in the city is about 0.5-1 km2; outside the city, depending on the geographical location, it can reach 20 or 50 km2. Telephone traffic in each “cell” is controlled by a base station, which receives and transmits signals over a large range of radio frequencies (dedicated channel - a minimal step for each cell phone). The base station is connected to a wired telephone network and is equipped with equipment for converting a high-frequency signal from a cell phone into a low-frequency signal from a wired phone and vice versa, which ensures the interfacing of these two systems. Technically modern base station equipment occupies an area of 1...3 m2 and is located within one small room, where its work is carried out in automatic mode. For stable operation of such a station, you only need a wired connection with a telephone exchange (PBX) and a 220 V mains power supply.
In cities and towns with a large concentration of houses, base station transmitters are located directly on the roofs of houses. In suburban and open areas, towers in several sections are used (they can often be seen located along highways).
The coverage area of neighboring stations is contiguous. When a telephone device moves between coverage areas of neighboring stations, it is periodically registered. Periodically, with an interval of 10...60 minutes (depending on the operator), the base station emits a service signal. Having accepted it, the mobile phone automatically adds its MIN and ESN numbers to it and transmits the resulting code combination to the base station. Thus, the identification of a specific mobile cellular telephone device, the account number of its owner and the binding of the device to a specific zone in which it is located at a given time is carried out. This point is very important - already at this stage it is possible to control the movements of this or that object, but who benefits from this is another question - the main thing is the opportunity...
When a user connects to someone on his phone, the base station allocates him one of the free frequencies of the zone in which he is located, makes appropriate changes to his account (debits funds) and transfers his call to its destination.
If mobile user during a conversation moves from one communication zone to another, the base station of the zone (cell) being left automatically transfers the communication signal to the free frequency of the zone (cell) adjacent to it.
The analog principle of information transmission is based on the emission of a non-digital radio signal into the air, therefore, by tuning to the appropriate frequency of such a communication channel, it is theoretically possible to listen to the conversation. However, it’s worth “cooling down particularly hot heads” - listening to cellular communications of this standard is not so easy, since they are encrypted (distorted) and for accurate speech recognition you need an appropriate decoder. Negotiations of this standard are easier to find than, say, the GSM standard - digital cellular communications, whose mobile phones transmit and receive information in the form of a digital code. The easiest way to find direction is stationary or stationary objects that provide cellular communications; it is more difficult to find mobile ones, since the movement of the subscriber during a conversation is accompanied by a decrease in signal strength and a transition to other frequencies (when transmitting a signal from one base station to a neighboring one).
Direction Finding Methods
The first is a method of targeted direction finding of a cell phone, which determines the direction to a working transmitter from three to six points and gives a pinpoint location of the radio signal source. The peculiarity of this method is that it can be applied by order of someone, for example, authorities authorized by law.
The second method is through a cellular operator, which automatically constantly registers where a particular subscriber is at a given moment in time, even when he is not conducting any conversations. This registration occurs automatically using identifying service signals automatically transmitted by the cell phone to the base station (this was discussed earlier). The accuracy of determining the subscriber's location depends on a number of factors: the topography of the area, the presence of interference and signal reflection from buildings, the position of base stations and their load (number of active mobile phones operator in a given cell), cell size. Hence, the accuracy of determining the location of a cellular subscriber in the city is noticeably higher than in open areas, and can reach a spot of several hundred meters. Analysis of data on the subscriber's communication sessions with various base stations (from which and to which station the call was made, time of the call, etc.) allows us to reconstruct a picture of all the subscriber's movements in the past. The data is automatically registered with the mobile operator (for billing and more...), since payment for such services is based on the duration of use of the communication system. This data can be stored for several years, and this time is not yet regulated by federal law, only by departmental acts.
You can conclude that confidentiality is ensured, but not for everyone. If it is necessary to listen to your communications, or determine your location, almost any “equipped” intelligence service or criminal community is able to do this without any effort.
It is more difficult to intercept a conversation if it is being conducted from a moving car, because... The distance between the cell phone user and the direction-finding equipment (if we are talking about analog communications) is constantly changing and if these objects move away from each other, especially in rough terrain among houses, the signal weakens. When moving quickly, the signal is transferred from one base station to another, with a simultaneous change in operating frequency - this makes it difficult to intercept the entire conversation (unless it is conducted purposefully with the participation of a telecom operator), since it takes time to find a new frequency.
You can draw conclusions from this yourself. Turn off your cell phone if you do not want your location to be known.
Hidden features of cell phones
A modern MTA can switch into voice recorder mode (recording sounds from the built-in microphone) automatically according to a signal, or a given program, without the permission of its owner. It is not a fact that every MTA records the owner’s speech and voice and then transmits the information, but such a possibility is technically provided in every modern MTA. It's like having a gun hanging on the wall. And if the action takes place during a performance in a theater, then it is almost obvious that before the end of the performance the gun will fire. So in this case, the MTA has the ability to record and transmit information, and this factor must be taken into account when using your “mobile phone”.
The information is received by the station closest to the MTA - the cell. How is information transmitted over the air? The MTA communicates with the station in bursts of digital pulse signals, which are called time slots. The duration of one service communication session can last from a fraction of a second to several seconds.
The MTA carries out such service communication sessions with the base station constantly when the cell phone is turned on. Initially, this occurs after the MTA is turned on, then the phone, communicating with the nearest communication station of its operator (according to the installed SIM card), positions its position on the ground, broadcasts its data (for example, the identification number of the cell phone on the network, etc.) , i.e. it is registered on the network. Based on this registration, during subsequent negotiations, this subscriber is charged for connections, communication services, call tariffs and roaming. In addition to time slots in a communication session when the power is turned on, the MTA periodically, approximately once an hour (and during active movement, constantly) communicates with a nearby base station, positioning its position and, if necessary (going beyond the cell) registering in the zone responsibility of another neighboring base station. The duration and frequency of service communication sessions (time slots) for different MTAs is different and ranges (frequency) from 10 to 35 times a day. In this case, the duration of time slots varies in the range of 2-25 milliseconds.
Many modern MTAs automatically include functions for various types of service informing the owner, for example, about the weather forecast or news, so the time slots for such a phone will be more frequent and longer. In this case, it is impossible to determine exactly what signals your mobile phone sends to the base station without special equipment. One can only record the very fact of a short communication session that occurred without the participation of the MTA owner. In any case, if you receive an SMS message, then time slots have been exchanged.
Every cell phone owner needs to know this feature of “their” MTA, despite the fact that manufacturing companies are in no hurry to either share this information with buyers of their products or explain these functions and their purpose. As they say, forewarned is protected... An indirect sign of the MTA operating at high power transmission is a rapidly discharging battery.
How to check a cell phone
At the dawn of the mass popularization of cell phones (and this was not so long ago), the population was dominated by mobile telephone devices (MTAs), purchased abroad and requiring Russification. In addition, some cell phones brought from abroad to the CIS (purchased on the secondary market because they were cheap) turned out to be blocked when connecting to a local operator’s SIM card (they did not implement some of the functions stated in the MTA menu and in its operating manual) . People took the MTA to the appropriate service (according to the name of the MTA) and sometimes received the answer: your phone will not work in Russia. Since then, MTAs, brought privately from abroad, began to be secretly divided into “white” and “gray”. "White" can be revived and used in the CIS "by full program“, and the “gray” ones are practically hopeless, or require such investments that they outweigh their very cost. Therefore, for some time now, “gray” mobile devices come to Russia only in single copies, or in batches imported by small “shuttles”, or after Russians vacation abroad, due to their ignorance. In this regard, a test method for checking MTA was born.
To test, you need to press the keys on the keyboard in sequence: *#06#. As a result, the series and model number indicated in the passport data will be displayed. The same data is printed on the MTA body under the battery. How will they help?
The specified data is the IMEI (International Mobile Equipment Identifier) of your MTA. After this notification procedure cellular company, your MTA, along with the SIM card (or even the newly inserted one), will be under the control of your cellular operator. It is better to find out this number in advance (when purchasing or operating the MTA) and write it down somewhere away from prying eyes. If the device is lost or stolen, this data must be transferred to your cellular operator. This is necessary to ensure that your MTA is definitely found, or at least blocked from service by the operator that you used before you lost your phone.
Communication is called mobile if the source of information or its recipient (or both) move in space. Radio communication has been mobile since its inception. The first radio stations were intended for communication with moving objects - ships. After all, one of the first radio communication devices A.S. Popov was installed on the battleship Admiral Apraksin. And it was thanks to radio communications that it was possible to contact him in the winter of 1899–1900. save this ship trapped in ice in the Baltic Sea.
For many years, individual radio communications between two subscribers required their own separate radio communication channel operating on the same frequency. Simultaneous radio communication over many channels could be ensured by allocating a specific frequency band to each channel. But frequencies are also needed for radio broadcasting, television, radar, radio navigation, and military needs. Therefore, the number of radio communication channels was very limited. It was used for military purposes and government communications. Thus, mobile phones were installed in the cars used by members of the Politburo of the CPSU Central Committee. They were installed in police cars and radio taxis. In order for mobile communications to become widespread, a new idea for its organization was needed.
Each cell must be served by a core radio transmitter with a limited range and a fixed frequency. This makes it possible to reuse the same frequency in other cells. During a conversation, the cellular radiotelephone is connected to the base station by a radio channel through which the telephone conversation is transmitted. The cell size is determined by the maximum communication range of the radiotelephone device with the base station. This maximum range is the radius of the cell.
The idea of mobile cellular communication is that, without yet leaving the coverage area of one base station, the mobile phone falls into the coverage area of any neighboring one, up to the outer border of the entire network zone.
For this purpose, systems of repeater antennas have been created that cover their “cell” - an area of the Earth’s surface. For reliable communication, the distance between two adjacent antennas must be less than their range. In cities it is about 500 m, and in rural areas – 2-3 km. A mobile phone can receive signals from several repeater antennas at once, but it is always tuned to the strongest signal.
The idea of mobile cellular communications was also the use of computer control over the telephone signal from the subscriber when he moves from one cell to another. It was computer control that made it possible to switch a mobile phone from one intermediate transmitter to another within just a thousandth of a second. Everything happens so quickly that the subscriber simply does not notice it.
Computers are the central part of a mobile communication system. They find a subscriber located in any of the cells and connect him to the telephone network. When a subscriber moves from one cell to another, they transfer the subscriber from one base station to another, and also connect the subscriber from a “foreign” cellular network to “their own” when he is within its coverage area - they perform roaming (which in English means “wandering” or “wandering”).
Operation of Europe's first cellular communication system, standard NMT-450 (Nordic Mobile Telephone), designed to operate in the 450 MHz band, began in 1981 in Sweden, Iceland, Denmark, Norway, Finland and Saudi Arabia. Then the operation of communication systems of the same type began in Europe and Southeast Asia. In 1985, on the basis of this standard, the NMT-900 standard in the 900 MHz range was developed, which made it possible to increase the subscriber capacity of the communication system. Similar standards have been introduced in the USA, France and the UK.
However, all these standards are analog and belong to the first generation of cellular communication systems. They use an analog method of transmitting information using frequency (FM) or phase (PM) modulation, as in conventional radio stations. This method has a number of significant disadvantages, the main of which are the ability to listen to conversations of other subscribers and the inability to combat signal fading when the subscriber moves and under the influence of landscape and buildings. Overloaded frequency bands caused interference during conversations.
Therefore, by the end of the 1980s. The creation of the second generation of cellular communication systems based on digital signal processing methods began. In 1990, the GSM-900 standard was developed for the 900 MHz range, which stands for Global System for Mobile Communications. And in 1991, based on GSM, a standard was developed for the 1800 MHz range. Similar standards have been adopted in the USA and Japan.
In Russia, analog cellular communication systems based on the NMT-450 standard appeared 10 years late, but digital systems based on the GSM standard appeared only three years late. The NMT and GSM standards have been approved in our country as federal standards. In Moscow, cellular networks based on the GSM digital standard are most actively developing, and in the regions - analogue networks. GSM standard systems in Russia are most actively promoted on the market by three operators - MTS, Beeline and MegaFon. Today, more than 70% of all cell phones in the world operate based on this standard. Russia benefited from its delay in introducing cellular communications. We immediately adopted the GSM digital standard. Many modern cell phones are equipped with high-speed Internet access using the GPRS (General Packet) standard. Radio Service).
Personal cellular mobile communications are becoming increasingly popular, especially among young people. The total number of its users in the world exceeds 600 million subscribers.
An important advantage of mobile cellular communications is the ability to use it outside the general area of your operator - roaming. To do this, various operators agree among themselves on the mutual possibility of using their zones for users. A subscriber, leaving the general area of his operator, automatically switches to the areas of other operators, even when moving from one country to another, for example, from Russia to Germany or France. Or, while in Russia, the user can make cellular calls to any country. Thus, cellular communications provide the user with the ability to communicate by telephone with any country, no matter where he is.
6.3.1. Organization of a cellular network
Cell phones are no longer a luxury or a business necessity. They are part of our daily life, actively changing both the style and content of our everyday lives. The basic idea of organizing a cellular telephone network is extremely simple. The entire serviced territory is divided into pieces called cells, in which there are base stations that connect mobile phones to each other and to the outside world. On the map, such a mobile communication network resembles a honeycomb, hence the name of this type of telecommunication. Phones in neighboring cells do not interfere with each other because they operate at different frequencies, but those located more than a cell apart simply do not hear each other due to the fact that the earth is round, and radio waves are attenuated as they propagate.
The base station with antennas and the handset in the subscriber’s hands are always close to each other and operate at minimal power, so the phone becomes truly mobile, compact and lightweight. The base stations are connected to each other by a high-speed communication line, through which our conversations reach the cellular operator. Having gathered at the main cellular station, all calls are charged and switched to the recipients. Naturally, cellular operators have access to the public telephone network, and a call, if it passes outside this network, begins its journey along earthly communication lines.
Thanks to unified management When moving from cell to cell, the phone is automatically transferred to the service of a new base station. The handover process is accompanied by a change in operating frequency and takes some time, almost unnoticeable during a conversation.
A mobile phone does not have a permanent registration, and it has to periodically register on the network; accordingly, the mobile operator, even when roaming (i.e. when its subscriber travels through a foreign territory), knows exactly where the connecting device is located, and upon request confirms solvency owner of the phone.
6.3.2. Analog cellular standards
Having much in common, cellular communication systems differ significantly from each other and, first of all, they use analogue or digital forms of information transmission. At first, all systems were analog, and the devices were very similar to ordinary radios. The two most widely spread systems around the world are the American AMPS (Advanced Mobile Phone Service) and European NMT (Nordic Mobile Telephone). Today they still operate successfully in large areas of sparsely populated areas of large countries, when the density of callers is low. These standards have limited capacity and do not allow more than fifty people to simultaneously communicate within one cell.
AMPS operates in the range of 800 MHz, NMT-450 - accordingly, near 450 MHz, and NMT-900, actively used today in the Scandinavian countries, is about 900 MHz. In NMT the maximum cell radius can be 40 km, in AMPS it is no more than 20 km. The output power of mobile handsets in NMT-450 reaches 2-3 W, in AMPS it does not exceed 0.6 W, for stationary and automotive options in NMT-450 it can reach up to 15 W, and in the base station – 50–100 W.
The audio signal in analog networks is not subject to significant processing, and the communication delay is only a few tens of milliseconds for local calls. Accordingly, the sound of the human voice in such phones looks most natural and familiar. The noise and interference characteristic of analogue networks are in many ways similar to the rustling and crackling noises typical of wired telephones.
In analog cellular systems, the issue of confidentiality of telephone conversations is completely open, and curious competitors can freely listen to conversations that interest them, not only sitting in a car under the office windows, but also being a couple of blocks from the object of observation. Moreover, almost immediately, “improved” models of analog phones appeared that were capable of intercepting the identification numbers of legitimate users of cellular networks. Moreover, the illegal machines calling at someone else’s expense were quite intelligent, and before going on air, they checked whether the person paying for them was in touch.
Theft has become so widespread in the world of analog cellular communications that equipment manufacturers have urgently had to make it more difficult to identify their subscribers. And today the problem of doubles, at least in NMTi, has been solved. However, the ability to eavesdrop even when “encryption” is enabled remains.
Roaming on cellular networks is only possible within the standard you choose, since phones operating on different standards are fundamentally incompatible. Right where it is desired network, so-called semi-automatic roaming takes place, requiring the participation of the owner to select the desired country code.
Until recently, NMT phones were significantly larger than their cellular counterparts, but today, thanks to advances in electronics, only a retractable antenna sometimes gives away the fact that this is an analog device.
In the United States, they very quickly encountered the fact that the analog standard cannot provide communications to everyone. And the new almost entirely digital standard D-AMPS (Digital Advanced Mobile Phone Service), which replaced AMPS, with the previous maximum cell radius of 20 km, increased the number of simultaneous conversations in the cell to three hundred. This was a step that significantly improved the confidentiality of telephone conversations and eliminated the problem of doubles. The transition to digital, naturally, had a slight impact on the quality of speech. This standard makes it possible to quite easily provide stable mobile communications to not too densely located subscribers. It has not become an international standard, so when traveling around the world with such a phone, you will not be able to get in touch everywhere.
Nine analog standards were developed and implemented around the world, operating at different frequencies and incompatible with each other. Now two of them are successfully operating: the Scandinavian NMT and the American AMPS, and both are used in our country.
6.3.3. Evolution to digital standards
Today there are 4 digital standards with the possibility of organizing cells with a radius of 0.5 to 20–30 km: American D-AMPS and CDMA, global pan-European GSM and purely Japanese JDC (Japan Digital Cell).
It is always more difficult for first movers, and today, in order to stay afloat, cellular operators operating in NMT and D-AMPS have to not only reduce prices, but also offer services that these standards did not initially provide. Auto dialing, number identification, voicemail, conference calls, data transfer and even work on the Internet today have become available not only to modern digital standards.
The widespread popularity of cellular networks has forced developers to seriously think about increasing their capacity and standardizing them throughout the planet. Because only with the unification of phones can you safely travel around the world, staying connected thanks to automatic roaming services. By this time, the beginning of the 90s, it was already clear that the solution to these two problems was possible only through the transition to digital ways voice transmission and communication control.
The development of a global standard was undertaken in both Europe and America. The Old and New Worlds took slightly different paths, and as a result there are two standards that operate not only at different frequencies, but also fundamentally use different ways separation of simultaneously calling subscribers. The Americans, in the same frequency band where AMPS and D-AMPS worked before, began introducing CDMA (Code Division Multiple Access) in 1995. With the same cell size and the same basic infrastructure, the transition to the new standard increased the number of simultaneous callers in a cell to a thousand, increased the efficiency of the devices, significantly improved the confidentiality of conversations and eliminated the problem of doubles.
Each CDMA phone has its own individual identification number, and it is simply impossible to change the device without the participation of the cellular operator. Apparently, this is also why there have been no reports of cloning (i.e. duplication) of this type of phone. The address book with numbers and your personal organizer end up in the phone’s permanent memory, and when changing the phone, you will have to overwrite all useful information.
Digital systems pay a lot of attention to speech coding, because without compression of the information flow, digital systems will not receive an advantage in the number of subscribers served. The computing capabilities of a telephone microcomputer responsible for encoding and decoding speech are far from any Pentium, and therefore it is timely not to complain about the quality of speech transmission in digital mobile communication systems, but to admire the fact that the voices of the most diverse peoples of the world are transmitted in such a recognizable way.
6.3.4. CDMA and GSM
CDMA has the most higher speed data transfer (14.4 kbit/s) and fairly good sound quality. Devices operating in this standard are quite miniature and stay connected for quite a long time. This standard is now widely used in North America and South Korea. In our country there are also operators who have chosen this standard, but the prevalence of such networks is still low, and potential roaming is very limited (and in a situation where this connection licensed as wireless only, and is not legally possible).
The most popular type of cellular communication today is, of course, GSM (Global System for Mobile Communications). This European digital standard for global mobile communications, launched in 1991 in Europe, has today become the de facto most popular standard in the world. It is spreading very quickly across our planet, and today in almost all countries, having a GSM phone in your hands, you can safely make and answer calls as if you were at home. GSM was developed taking into account many years of experience in operating cellular networks, is aimed at universal use and allows significant modification without changing the basic functions.
In GSM, the cell radius can reach 35 km, and up to a thousand simultaneous calls are possible. The maximum pulse power of mobile handsets does not exceed 1 W, although for landline and car versions of phones it can reach up to 20 W. Devices of this standard are by far the smallest and stay connected and waiting for a call the longest.
Digital communication systems provide clear and noise-free sound, only slightly distorting the timbre and intonation of speech. Only with weak signal levels and unstable connections is it possible that the phone seems to swallow pieces of words. The gains in output power and throughput when going digital are so significant, and speech intelligibility suffers so little, that you can definitely forgive phones for digitally processing human voices.
When talking, we remain silent about half the time, listening to the interlocutor. Digital systems actively use this circumstance, almost completely turning off the transmitter during speech pauses, trying not to unnecessarily pollute the airwaves and saving the battery. And to avoid ringing silence in the speaker’s ears, the phone at this time sends “comfortable noise” into the speaker, reminiscent of the typical sounds at the other end of the “wire.”
Over-the-air eavesdropping on GSM conversations is difficult, but the developers did their best here. And the point is not only in the complex type of signals used and the closed nature of the encryption algorithms, but also in the fact that the encoding procedure changes all the time, and each new call has its own key.
An interesting step in the fight for caller density was the introduction of GSM 1800, which significantly increased capacity by moving to smaller cells and expanding the frequency range. Judging by the experience of operating such networks in the largest metropolitan areas, this step completely eliminates the problem of network overload even with the complete “mobilization” of the population.
All over the world, GSM operates at 900 and 1800 MHz, but not in America. The Federal Radio Communications Commission considered it free and sold only a small part of the spectrum in the region of 1900 MHz to operators, and the American GSM 1900 immediately appeared. Moreover, both GSM and CDMA and even D-AMPS cellular operators can operate in this range. Today, not only “worldwide” phones are produced that operate on 1800 and 1900 MHz, but also truly omnivorous “three-band” phones that can communicate in all three GSM bands.
Cellular networks and the Internet are in many ways similar to each other, and it is no coincidence that almost all GSM phones have WAP browsers and projects of a new worldwide cellular communication standard are being actively discussed, which will have a significantly higher data transfer speed and provide quite comfortable work on the World Wide Web thanks to a wider working band and increased rate of speech, images and data transmission compared to GSM and CDMA. Today, such a superstructure over GSM in the form of GPRS technology has already been mastered by both Moscow operators and a reception speed of 40.2 kbit/s has been achieved.
GSM phones use a removable module responsible for subscriber identification - the so-called SIM card (Subscribe Identity Module). This small chip is not only responsible for ensuring that no one calls for your money, but also contains an extensive memory that can store up to 255 numbers and names of your friends. Accordingly, by moving the SIM card from one GSM phone to another, you transfer not only your address book, but also your telephone number, which will now actually be answered by another phone.
Personalization of communications goes fast pace, and today you can safely move from the concept of “work” and “home” telephone to the concept of “personal individual telephone number”, which is always with you. The most logical solution to this problem is the use of SIM cards. The versatility of this small chip allows it to be used in all new, ready-to-launch and development of both cellular and satellite communication systems.
The range of services provided today by GSM operators is the most extensive, and it is constantly expanding. Short text messages SMS (Short Message Service) and the ability to work on the Internet directly from the phone keyboard using a WAP browser, data and fax transmission (speed 9.6 kbit/s), conference calls and call forwarding, information services (prices, weather, addresses, telephone numbers) and the formation of various user groups - this is not a complete list of the opportunities that the owner of a GSM phone receives.
The section of cellular standards has already been completed, and almost all operators chose one type of communication. There are several dozen working in our country today mobile operators, serving nearly two million users. The Moscow operator Bee Line, having deployed its D-AMPS network, did not introduce CDMA in the same range, but moved on to European GSM 1800. Another metropolitan operator, MTS, began working in GSM 900, and now they both rely on dual-band GSM 900/1800. The oldest Russian cellular network MCC, together with SOTEL, continues to cover the vast expanses of our Motherland with the NMT-450i standard, thinking about digitalization. Regional operators are successfully mastering all cellular communication standards, including CDMA. The Moscow SONET network has chosen CDMA for now in a stationary form, but in the future, of course, in a mobile form.
And if operators provide services in different standards, then manufacturers are trying to maximize the capabilities of cell phones, making them more and more functional and multi-standard. The combination of satellite, cellular and office radiotelephones in one package is now in full swing, and in the 21st century. it will be quite possible to call in the desert satellite channel, in the city - by cell phone, and in the office - by local radio-PBX, and all this will happen using one device and a single personal number of the phone owner.
Leading cell phone manufacturing companies are guided by a single European standard - GSM. That is why their equipment is technically advanced, but relatively inexpensive. After all, they can afford to produce huge quantities of phones that are sold.
A convenient addition to cell phone became the short message system SMS (Short Message Service). It is used to transfer short messages directly to the phone of a modern digital GSM system without the use of additional equipment, only using a numeric keypad and a cell phone display screen. SMS messages are also received on the digital display that any cell phone is equipped with. SMS can be used in cases where a regular telephone conversation is not the most convenient form of communication (for example, on a noisy, crowded train). You can send your phone number to a friend via SMS. Due to its low cost, SMS is an alternative to telephone conversation. The maximum length of an SMS message is 160 characters. You can send it in several ways: by calling a special service, using your GSM phone with a sending function, or using the Internet. The SMS system can provide additional services: send exchange rates, weather forecasts, etc. to your GSM phone. Essentially, a GSM phone with SMS is an alternative to a pager.
But the SMS system is not the last word in cellular communications. The most modern cell phones (for example, from Nokia) have the Chat function (in the Russian version - “dialogue”). With its help, you can communicate in real time with other cell phone owners, as is done on the Internet. Essentially this is new look exchanging SMS messages. To do this, you compose a message to your interlocutor and send it. The text of your message appears on the displays of both cell phones - yours and your interlocutor's. Then he answers you and his message is displayed on the displays. Thus, you are conducting an electronic dialogue. But if the cell phone of your interlocutor does not support this function, then he will receive regular SMS messages.
Cell phones have also appeared that support high-speed Internet access via GPRS (General Packet Radio Service) - a standard for packet data transmission over radio channels, in which the phone does not need to “dial up”: the device constantly maintains a connection, sends and receives data packets. Cellular telephones with a built-in digital camera are also produced.
According to the research company Informa Telecoms & Media (ITM), the number of mobile communications users in the world in 2007 was 3.3 billion people.
Finally, the most complex and expensive devices are smartphones and communicators that combine the capabilities of a cell phone and a PDA.
6.3.5. Messaging technologies Short Message Service (SMS)
Short Message Service (SMS) is by far the most common and used method of sending and receiving short messages via GSM mobile communications. SMS has proven itself well as a means of communication in the person-to-person direction and when sending messages, which are primarily informational in nature, from server to subscriber and between servers.
SMS is powered by an SMS center (Short Message Service Center or SMSC), which acts as a data bank where messages are stored and the vehicle that forwards them. Short messages are sent over the same cellular network channel as telephone calls. And in the case of a network that provides packet data transmission, messages can even be sent directly during a telephone conversation.
The specifications for standard short messages indicate that it cannot exceed 160 characters. Theoretically, the message could be 255 times larger, but, unfortunately, none of the existing telephones can store that amount of information. On average, their memory is designed for only four complete messages.
6.3.6. Multimedia Message Service (MMS)
MMS belongs to a new generation of mobile messaging solutions. Still not fully standardized, this service promises to add many features to phones that EMS cannot provide.
The MMS standard is intended for GPRS networks, which, unlike the simpler GSM, have a permanent connection to the network, higher bandwidth and the ability to transmit packet data, which, together with more powerful devices, ensures the transition to multimedia messages.
MMS is based on SMS and e-mail standards. It incorporated the best of both systems, resulting in a "hybrid" standard optimized for use with mobile devices. This allows you to simplify the integration process with existing systems, applications and, most importantly, users. One of the advantages of the new standard is that both telephone numbers and email addresses can be used when sending a message.
The Multimedia Message Service standard allows you to include text, pictures in JPEG format, audio files compressed using an AMR encoder, an SMS message hidden inside an MMS.
In the future, MMS plans to add support for video formats and various add-ons, such as Synchronized Multimedia Integration Language (SMIL), which will allow media data to be presented in a structured form.
Just as SMS requires a service center to store and send messages, MMS requires a service center to manage the flow of multimedia messages.
The MMS center (in the documentation it is called MMS Relay/Server) is responsible for the following set of tasks:
Receive and send media messages from and to mobile devices;
Converting media formats depending on the capabilities of the telephone to which the message is sent;
Generation of account information;
Receiving and delivering messages from and to foreign MMS centers;
Receiving and delivering messages from and to external systems, e.g. email;
Receiving and delivering messages to external providers providing additional services.
Operating principle of radio communication
Radio (lat. radio - I emit, I emit rays radius - ray) - a type wireless communication, in which radio waves, freely propagating in space, are used as a signal carrier.
Operating principle
The transmission occurs as follows: a signal with the required characteristics (frequency and amplitude of the signal) is generated on the transmitting side. Next, the transmitted signal modulates a higher frequency oscillation (carrier). The resulting modulated signal is radiated into space by the antenna. On the receiving side of the radio wave, a modulated signal is induced in the antenna, after which it is demodulated (detected) and filtered by a low-pass filter (thus getting rid of the high-frequency component - the carrier). The resulting modulated signal is radiated by the antenna into space.
On the receiving side of the radio wave, a modulated signal is induced in the antenna, after which it is demodulated (detected) and filtered by a low-pass filter (thus getting rid of the high-frequency component, the carrier). Thus, the useful signal is extracted. The received signal may differ slightly from that transmitted by the transmitter (distortion due to interference and interference).
Frequency ranges
The frequency grid used in radio communications is conventionally divided into ranges:
- Long waves (LW) - f = 150-450 kHz (l = 2000-670 m)
- Medium waves (SW) - f = 500-1600 kHz (l = 600-190 m)
- Short waves (HF) - f = 3-30 MHz (l = 100-10 m)
- Ultrashort waves (VHF) - f = 30 MHz - 300 MHz (l = 10-1 m)
- High frequencies (HF-centimeter range) - f = 300 MHz - 3 GHz (l = 1-0.1 m)
- Extremely high frequencies (EHF - millimeter range) - f = 3 GHz - 30 GHz (l = 0.1-0.01 m)
- Hyper-high frequencies (HHF - micrometer range) - f = 30 GHz - 300 GHz (l = 0.01-0.001 m)
Depending on the range, radio waves have their own characteristics and propagation laws:
- LWs are strongly absorbed by the ionosphere; the main importance is ground waves that propagate around the earth. Their intensity decreases relatively quickly as they move away from the transmitter.
- SWs are strongly absorbed by the ionosphere during the day, and the area of action is determined by the ground wave; in the evening, they are well reflected from the ionosphere and the area of action is determined by the reflected wave.
- HF propagate exclusively through reflection by the ionosphere, so there is a so-called radio silence zone around the transmitter. During the day, shorter waves (30 MHz) travel better, and at night, longer waves (3 MHz). Short waves can travel long distances with low transmitter power.
- VHF propagates in a straight line and, as a rule, is not reflected by the ionosphere. They easily bend around obstacles and have high penetrating ability.
- HF does not bend around obstacles and propagates within the line of sight. Used in WiFi, cellular communications, etc.
- EHFs do not bend around obstacles, are reflected by most obstacles, and propagate within line of sight. Used for satellite communications.
- Hyper-high frequencies do not bend around obstacles, are reflected like light, and spread within the line of sight. Use is limited.
Radio propagation
Radio waves propagate in vacuum and in the atmosphere; the earth's surface and water are opaque to them. However, due to the effects of diffraction and reflection, communication is possible between points on the earth's surface that do not have direct visibility (in particular, those located at a great distance).
The propagation of radio waves from a source to a receiver can occur in several ways simultaneously. This propagation is called multipath. Due to multipath and changes in environmental parameters, fading occurs - a change in the level of the received signal over time. With multipath, a change in signal level occurs due to interference, that is, at the receiving point, the electromagnetic field is the sum of time-shifted radio waves of the range.
Radar
Radar- a field of science and technology that combines methods and means of detection, measuring coordinates, as well as determining the properties and characteristics of various objects based on the use of radio waves. A related and partly overlapping term is radio navigation, however, in radio navigation, a more active role is played by the object whose coordinates are measured, most often this is the determination of its own coordinates. The main technical device of radar is a radar station.
There are active, semi-active, active with a passive response and passive RL. They are divided according to the radio wave range used, the type of probing signal, the number of channels used, the number and type of coordinates being measured, and the location of the radar installation.
Operating principle
Radar is based on the following physical phenomena:
- Radio waves are scattered by electrical inhomogeneities encountered along the path of their propagation (objects with other electrical properties that differ from the properties of the propagation medium). In this case, the reflected wave, as well as the target radiation itself, makes it possible to detect the target.
- At large distances from the radiation source, it can be assumed that radio waves propagate rectilinearly and at a constant speed, due to which it is possible to measure the range and angular coordinates of the target (Deviations from these rules, which are valid only as a first approximation, are studied by a special branch of radio engineering - Radio wave propagation. In radar these deviations lead to measurement errors).
- The frequency of the received signal differs from the frequency of the emitted oscillations when the receiving and emission points move mutually (Doppler effect), which makes it possible to measure the radial speeds of the target relative to the radar.
- Passive radar uses the emission of electromagnetic waves from observed objects; this can be thermal radiation, which is characteristic of all objects, active radiation created by the technical means of the object, or side radiation created by any objects with operating electrical devices.
Cellular connection
Cellular connection, mobile network- one of the types of mobile radio communications, which is based on cellular network. Key Feature lies in the fact that the total coverage area is divided into cells (cells), determined by the coverage areas of individual base stations (BS). The cells partially overlap and together form a network. On an ideal (flat and undeveloped) surface, the coverage area of one BS is a circle, so the network made up of them looks like a honeycomb with hexagonal cells (honeycombs).
The network consists of spatially dispersed transceivers operating in the same frequency range, and switching equipment that makes it possible to determine the current location of mobile subscribers and ensure continuity of communication when a subscriber moves from the coverage area of one transceiver to the coverage area of another.
Operating principle of cellular communication
The main components of a cellular network are cell phones and base stations, which are usually located on rooftops and towers. When turned on, the cell phone listens to the airwaves, finding a signal from the base station. The phone then sends its unique identification code to the station. The telephone and the station maintain constant radio contact, periodically exchanging packets. Communication between the phone and the station can be via an analog protocol (AMPS, NAMPS, NMT-450) or digital (DAMPS, CDMA, GSM, UMTS). If the phone leaves the range of the base station (or the quality of the radio signal from the service cell deteriorates), it establishes communication with another one. handover).
Cellular networks can consist of base stations of different standards, which allows optimizing network operation and improving its coverage.
The cellular networks of different operators are connected to each other, as well as to the landline telephone network. This allows subscribers of one operator to make calls to subscribers of another operator, from mobile phones to landlines and from landlines to mobiles.
Operators can enter into roaming agreements with each other. Thanks to such agreements, a subscriber, being outside the coverage area of his network, can make and receive calls through the network of another operator. As a rule, this is carried out at increased rates. The possibility of roaming appeared only in 2G standards and is one of the main differences from 1G networks.
Operators can share network infrastructure, reducing network deployment and operating costs.
Cellular services
Mobile operators provide the following services:
- Voice call;
- Autoresponder in cellular communications (service);
- Roaming;
- Caller ID (Automatic Caller ID) and Anti-Caller ID;
- Reception and transmission of short text messages (SMS);
- Reception and transmission of multimedia messages - images, melodies, videos (MMS service);
- Mobile banking (service);
- Internet access;
- Video call and video conference
TV
TV(Greek τήλε - far and lat. video- I see; from New Latin televisio- far vision) - a set of devices for transmitting moving images and sound over a distance. In everyday life it is also used to refer to organizations involved in the production and distribution of television programs.
Basic principles
Television is based on the principle of sequential transmission of image elements using a radio signal or wires. The image is decomposed into elements using a Nipkow disk, cathode ray tube or semiconductor matrix. The number of image elements is selected in accordance with the radio channel bandwidth and physiological criteria. To narrow the bandwidth of transmitted frequencies and reduce the noticeability of flickering on the TV screen, interlaced scanning is used. It also allows you to increase the smoothness of motion transmission.
The television channel in general includes the following devices:
- Television transmission camera. Serves to convert the image obtained using a lens on the target of the transmitting tube or semiconductor matrix into a television video signal.
- VCR. Records and plays back a video signal at the right time.
- Video mixer. Allows you to switch between several image sources: video cameras, VCRs and others.
- Transmitter. The radio frequency signal is modulated by the television video signal and transmitted by radio or wire.
- Receiver - TV. With the help of synchronization pulses contained in the video signal, the television image is reproduced on the receiver screen (kinescope, LCD display, plasma panel).
In addition, to create a television broadcast, an audio path similar to the radio transmission path is used. Sound is transmitted at a separate frequency, usually using frequency modulation, using technology similar to FM radio stations. IN digital television audio, often multi-channel, is transmitted in a common data stream with the image.
It is hardly possible today to find a person who has never used a cell phone. But does everyone understand how cellular communications work? How does what we have all become accustomed to work and work? Are signals from base stations transmitted through wires or does it all work somehow differently? Or maybe all cellular communications function only through radio waves? We will try to answer these and other questions in our article, leaving the description of the GSM standard outside its scope.
At the moment when a person tries to make a call from his mobile phone, or when they start calling him, the phone is connected via radio waves to one of the base stations (the most accessible), to one of its antennas. Base stations can be seen here and there, looking at the houses of our cities, at the roofs and facades of industrial buildings, at high-rise buildings, and finally at the red and white masts specially erected for stations (especially along highways).
These stations look like rectangular gray boxes, from which various antennas stick out in different directions (usually up to 12 antennas). The antennas here work for both reception and transmission, and they belong to the cellular operator. The base station antennas are directed in all possible directions (sectors) to provide “network coverage” to subscribers from all directions at a distance of up to 35 kilometers.
The antenna of one sector is able to service up to 72 calls simultaneously, and if there are 12 antennas, then imagine: 864 calls can, in principle, be serviced by one large base station at the same time! Although they are usually limited to 432 channels (72*6). Each antenna is connected by cable to the control unit of the base station. And blocks of several base stations (each station serves its own part of the territory) are connected to the controller. Up to 15 base stations are connected to one controller.
The base station is, in principle, capable of operating on three bands: the 900 MHz signal penetrates better inside buildings and structures and spreads further, so this band is often used in villages and fields; a signal at a frequency of 1800 MHz does not travel that far, but more transmitters are installed in one sector, so such stations are installed more often in cities; finally 2100 MHz is a 3G network.
Of course, there may be several controllers in a populated area or region, so the controllers, in turn, are connected by cables to the switch. The purpose of the switch is to connect the networks of mobile operators with each other and with city lines of regular telephone communication, long-distance communication and international communication. If the network is small, then one switch is enough; if it is large, two or more switches are used. The switches are connected to each other by wires.
In the process of moving a person talking on a mobile phone along the street, for example: he walks, drives public transport, or travels in a personal car - his phone should not lose the network for a moment, you cannot interrupt the conversation.
Continuity of communication is obtained due to the ability of a network of base stations to very quickly switch a subscriber from one antenna to another as he moves from the coverage area of one antenna to the coverage area of another (from cell to cell). The subscriber himself does not notice how he ceases to be connected to one base station and is already connected to another, how he switches from antenna to antenna, from station to station, from controller to controller...
At the same time, the switch provides optimal load distribution across a multi-level network design to reduce the likelihood of equipment failure. A multi-level network is built like this: cell phone - base station - controller - switch.
Let's say we make a call, and the signal has already reached the switchboard. The switch transmits our call towards the destination subscriber - to the city network, to the international or long-distance communication network, or to the network of another mobile operator. All this happens very quickly using high-speed fiber optic cable channels.
Next, our call goes to the switch, which is located on the side of the recipient of the call (the one we called). The “receiving” switch already has data about where the called subscriber is located, in what network coverage area: which controller, which base station. And so, a network survey begins from the base station, the recipient is located, and a call is received on his phone.
The entire chain of events described, from the moment the number is dialed to the moment the call is heard on the receiving end, usually lasts no more than 3 seconds. So today we can call anywhere in the world.
Andrey Povny
Mobile cellular communication
Cellular connection- one of the types of mobile radio communications, which is based on cellular network. The key feature is that the total coverage area is divided into cells (cells), determined by the coverage areas of individual base stations (BS). The cells partially overlap and together form a network. On an ideal (flat and undeveloped) surface, the coverage area of one BS is a circle, so the network made up of them looks like a honeycomb with hexagonal cells (honeycombs).
It is noteworthy that in the English version the connection is called “cellular” or “cellular” (cellular), which does not take into account the hexagonal nature of the honeycomb.
The network consists of spatially dispersed transceivers operating in the same frequency range, and switching equipment that makes it possible to determine the current location of mobile subscribers and ensure continuity of communication when a subscriber moves from the coverage area of one transceiver to the coverage area of another.
Story
The first use of mobile telephone radio in the United States dates back to 1921: Detroit police used one-way dispatch communications in the 2 MHz band to transmit information from a central transmitter to vehicle-mounted receivers. In 1933, the NYPD began using a two-way mobile telephone radio system, also in the 2 MHz band. In 1934, the US Federal Communications Commission allocated 4 channels for telephone radio communications in the range of 30...40 MHz, and in 1940 about 10 thousand police vehicles were already using telephone radio communications. All of these systems used amplitude modulation. Frequency modulation began to be used in 1940 and by 1946 it had completely replaced amplitude modulation. The first public mobile radiotelephone appeared in 1946 (St. Louis, USA; Bell Telephone Laboratories), it used the 150 MHz band. In 1955, an 11-channel system began operating in the 150 MHz band, and in 1956, a 12-channel system in the 450 MHz band began operating. Both of these systems were simplex and used manual switching. Automatic duplex systems began operating in 1964 (150 MHz) and 1969 (450 MHz), respectively.
In the USSR In 1957, Moscow engineer L.I. Kupriyanovich created a prototype of a portable automatic duplex mobile radiotelephone LK-1 and a base station for it. The mobile radiotelephone weighed about three kilograms and had a range of 20-30 km. In 1958, Kupriyanovich created improved models of the device, weighing 0.5 kg and the size of a cigarette box. In the 60s, Hristo Bochvarov demonstrated his prototype of a pocket mobile radiotelephone in Bulgaria. At the Interorgtekhnika-66 exhibition, Bulgaria is presenting a kit for organizing local mobile communications from pocket mobile phones RAT-0.5 and ATRT-0.5 and a base station RATC-10, providing connection for 10 subscribers.
At the end of the 50s, the development of the Altai car radiotelephone system began in the USSR, which was put into trial operation in 1963. The Altai system initially operated at a frequency of 150 MHz. In 1970, the Altai system operated in 30 cities of the USSR and the 330 MHz range was allocated for it.
In a similar way, with natural differences and on a smaller scale, the situation developed in other countries. Thus, in Norway, public telephone radio has been used for maritime mobile communications since 1931; in 1955 there were 27 coast radio stations in the country. Land mobile communications began to develop after the Second World War in the form of private, manually switched networks. Thus, by 1970, mobile telephone radio communications, on the one hand, had already become quite widespread, but on the other, it clearly could not keep up with the rapidly growing needs, with a limited number of channels in strictly defined frequency bands. A solution was found in the form of a cellular communication system, which made it possible to dramatically increase capacity by reusing frequencies in a system with a cellular structure.
Of course, as usually happens in life, certain elements of the cellular communication system existed before. In particular, some semblance of a cellular system was used in 1949 in Detroit (USA) by a taxi dispatch service - with the reuse of frequencies in different cells when users manually switched channels at predetermined locations. However, the architecture of the system that is today known as the cellular communication system was outlined only in the Bell System technical report submitted to the US Federal Communications Commission in December 1971. And from that time on, the development of cellular communications itself began, which became truly triumphant in 1985 g., in the last ten years or so.
In 1974, the US Federal Communications Commission decided to allocate a frequency band of 40 MHz in the 800 MHz band for cellular communications; in 1986 another 10 MHz was added in the same range. In 1978, tests of the first experimental cellular communication system for 2 thousand subscribers began in Chicago. Therefore, 1978 can be considered the year of the beginning of the practical use of cellular communications. The first automated commercial cellular telephone system was also introduced in Chicago in October 1983 by American Telephone and Telegraph (AT&T). In Canada, cellular communications have been used since 1978, in Japan - since 1979, in the Scandinavian countries (Denmark, Norway, Sweden, Finland) - since 1981, in Spain and England - since 1982. As of July 1997 cellular communications operated in more than 140 countries on all continents, serving more than 150 million subscribers.
The first commercially successful cellular network was the Finnish Autoradiopuhelin (ARP) network. This name is translated into Russian as “Car radiotelephone”. Launched in the city, it reached 100% coverage of the territory of Finland in. The size of the cell was about 30 km, and there were more than 30 thousand subscribers in the city. It worked at a frequency of 150 MHz.
Operating principle of cellular communication
The main components of a cellular network are cell phones and base stations. Base stations are usually located on the roofs of buildings and towers. When turned on, the cell phone listens to the airwaves, finding a signal from the base station. The phone then sends its unique identification code to the station. The telephone and the station maintain constant radio contact, periodically exchanging packets. Communication between the phone and the station can be via an analog protocol (NMT-450) or digital (DAMPS, GSM, English). handover).
Cellular networks can consist of base stations of different standards, which allows optimizing network operation and improving its coverage.
The cellular networks of different operators are connected to each other, as well as to the landline telephone network. This allows subscribers of one operator to make calls to subscribers of another operator, from mobile phones to landlines and from landlines to mobiles.
Operators different countries may enter into roaming agreements. Thanks to such agreements, a subscriber, while abroad, can make and receive calls through the network of another operator (albeit at higher rates).
Cellular communications in Russia
In Russia, cellular communications began to be introduced in 1990, commercial use began on September 9, 1991, when the first cellular network in Russia was launched in St. Petersburg by Delta Telecom (operating in the NMT-450 standard) and the first symbolic cell phone call by the mayor of St. Petersburg Anatoly Sobchak. By July 1997 total number subscribers in Russia amounted to about 300 thousand. As of 2007, the main cellular communication protocols used in Russia are GSM-900 and GSM-1800. In addition, UMTS also works. In particular, the first fragment of a network of this standard in Russia was put into operation on October 2, 2007 in St. Petersburg by MegaFon. In the Sverdlovsk region, the cellular communication network of the DAMPS standard, owned by the MOTIV Cellular Communications company, continues to be used.
In Russia in December 2008, there were 187.8 million cellular users (based on the number of SIM cards sold). The penetration rate of cellular communications (the number of SIM cards per 100 inhabitants) on this date was thus 129.4%. In the regions, excluding Moscow, the penetration level exceeded 119.7%.
The market share of the largest mobile operators as of December 2008 was: 34.4% for MTS, 25.4% for VimpelCom and 23.0% for MegaFon.
In December 2007, the number of cellular users in Russia grew to 172.87 million subscribers, in Moscow - to 29.9, in St. Petersburg - to 9.7 million. Penetration level in Russia - up to 119.1%, Moscow - 176% , St. Petersburg - 153%. The market share of the largest cellular operators as of December 2007 was: MTS 30.9%, VimpelCom 29.2%, MegaFon 19.9%, other operators 20%.
According to British research company Informa Telecoms & Media for 2006, the average cost of a minute of cellular communication for a consumer in Russia was $0.05 - this is the lowest among the G8 countries.
The IDC company, based on a study of the Russian cellular communications market, concluded that in 2005 the total duration of cell phone calls by residents of the Russian Federation reached 155 billion minutes, and 15 billion text messages were sent.
According to a study by J"son & Partners, the number of SIM cards registered in Russia as of the end of November 2008 reached 183.8 million.
See also
Sources
Links
- Information site about generations and standards of cellular communications.
- Cellular communications in Russia 2002-2007, official statistics
| Cellular connection in Russia | |
|---|---|
| Cellular operators | Utel Akos Altaisvyaz Baikalwestcom Beeline ETK MegaFon Motive MTS NSS NTK SMARTS Sky Link Sonet Sotel SSB STEK GSM TomskTeleCom UUSS Digital expansion |
| Cell phone sales networks | Divizion Symphony AltTelecom Banzai Betalink Euroset ION Svyaznoy Spectrum Communication Telephone.Ru Teleforum Tochka Ultra Digital City Eldorado |
| Cellular standards | D-AMPS GSM IMT-MC-450 IS-95 |
