It is a little sad that the vast majority of people, when asked: “How does cellular?”, answer “by air” or in general - “I don’t know”.

In continuation of this topic, I had one funny conversation with a friend on the topic of mobile communications. It happened exactly a couple of days before being celebrated by all signalmen and telecom operators radio day celebration. It so happened that, due to his ardent position in life, my friend believed that mobile communication works without wires at all via satellite. Exclusively due to radio waves. At first, I couldn't convince him. But after a short conversation, everything fell into place.

After this friendly "lecture", the idea came up to write in simple language about how cellular communications work. Everything is as it is.

When you dial a number and start to call, well, or someone calls you, then your mobile phone communicates via radio from one of the antennas of the nearest base station. Where are these base stations, you ask?

pay attention to industrial buildings, urban skyscrapers and special towers. On them are large gray rectangular blocks with protruding antennas of various shapes. But these antennas are not television or satellite, but transceivers mobile operators. They are directed to different sides to provide communication to subscribers from all directions. After all, we don’t know where the signal will come from and where it will bring the “unfortunate subscriber” from handset? Antennas are also called "sectors" in professional jargon. As a rule, they are installed from one to twelve.

From the antenna, the signal is transmitted via cable directly to the control unit of the station. Together they form the base station [antennas and control unit]. Several base stations, whose antennas serve a separate area, for example, a city area or a small town, are connected to a special unit - controller. Up to 15 base stations are usually connected to one controller.

In turn, the controllers, which can also be several, are connected by cables to the "think tank" - switch. The switch provides output and input of signals to city telephone lines, to other cellular operators, as well as long-distance and international operators.

In small networks, only one switch is used, in larger networks serving more than a million subscribers at once, two, three or more switches can be used, again interconnected by wires.

Why such complexity? Readers will ask. It would seem that, you can simply connect the antennas to the switch and everything will work. And then there are base stations, switches, a bunch of cables ... But, not everything is so simple.

When a person moves along the street on foot or goes by car, train, etc. and at the same time talking on the phone, it is important to ensure communication continuity. Signalers handover process in mobile networks called the term handover. It is necessary to switch the subscriber's phone in time from one base station to another, from one controller to another, and so on.

If the base stations were directly connected to the switch, then all these switching would have to be controlled by the switch. And he "poor" and so there is something to do. A multi-level network scheme makes it possible to evenly distribute the load on technical means . This reduces the likelihood of equipment failure and, as a result, loss of communication. After all, we all interested in uninterrupted communication, right?

So, reaching the switch, our call is being translated further - to the network of another operator of mobile, urban intercity and international communications. Of course, this happens over high-speed cable communication channels. The call arrives at the switch another operator. At the same time, the latter “knows” in which territory [in the scope of which controller] the desired subscriber is currently located. The switch transmits phone call to a specific controller, which contains information about which base station the call recipient is in the coverage area of. The controller sends a signal to this single base station, and it in turn “polls”, that is, calls the mobile phone. A tube starts ringing strangely.

This whole long and complicated process actually takes 2-3 seconds!

Exactly the same happens phone calls in different cities Russia, Europe and the world. Contact switches of various telecom operators use high-speed fiber optic communication channels. Thanks to them, a telephone signal overcomes hundreds of thousands of kilometers in a matter of seconds.

Thanks to the great Alexander Popov for giving the world radio! If not for him, perhaps we would now be deprived of many of the benefits of civilization.

It is hardly possible today to find a person who would never use a cell phone. But does everyone understand how cellular communication works? How is it arranged and how does what we all have long been accustomed to work? Are signals from base stations transmitted over wires, or does it all work in some other way? Or maybe all cellular communication functions only due to radio waves? We will try to answer these and other questions in our article, leaving the description of the GSM standard beyond 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 connects via radio waves to one of the base stations (the most accessible), to one of its antennas. Base stations can be observed here and there, looking at the houses of our cities, at the roofs and facades of industrial buildings, at skyscrapers, and finally at red-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 both for reception and for transmission, and they belong to the mobile operator. Base station antennas are directed in all possible directions (sectors) to provide “network coverage” to subscribers from all sides at a distance of up to 35 kilometers.

An antenna of one sector is able to serve up to 72 calls simultaneously, and if there are 12 antennas, then imagine: 864 calls can, in principle, be served by one large base station at the same time! Although usually limited to 432 channels (72 * 6). Each antenna is connected by cable to the control unit of the base station. And already blocks of several base stations (each station serves its own part of the territory) are attached to the controller. Up to 15 base stations can be connected to one controller.

The base station, in principle, is capable of operating on three bands: the 900 MHz signal penetrates better into buildings and structures, spreads further, so this particular band is often used in villages and fields; the signal at a frequency of 1800 MHz does not spread so far, but more transmitters are installed in one sector, so such stations are more often installed in cities; finally 2100 MHz is a 3G network.

Of course, there may be several controllers in a settlement or district, so the controllers, in turn, are connected by cables to the switch. The task of the switch is to connect the networks of mobile operators with each other and with city lines of the usual telephone connection, long distance communication and international communications. If the network is small, then one switch is enough; if it is large, two or more switches are used. The switches are interconnected by wires.

In the process of moving a person talking on a mobile phone along the street, for example: he walks, goes to public transport, or moves in a personal car - his phone should not lose the network for a moment, you cannot cut off the conversation.

Communication continuity is obtained due to the ability of the base station network to very quickly switch the subscriber from one antenna to another in the process of moving 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 with 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 over a multi-layer network scheme in order to reduce the likelihood of equipment failure. A multilevel network is built like this: cell phone - base station - controller - switch.

Let's say we make a call, and now the signal has already reached the switch. The switch transfers 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.

Further, our call arrives at the switchboard, which is located on the side of the receiving call (called by us) subscriber. 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, the network polling begins from the base station, the addressee is found, and a call “receives” on his phone.

The entire chain of the described events, from the moment of dialing the number to the moment the call is heard on the receiving side, usually lasts no more than 3 seconds. So we can now call anywhere in the world.

Andrey Povny

The most common type of mobile communication today is cellular communication. Cellular communication services are provided to subscribers by operating companies.

A network of base stations provides wireless communication to a cell phone.

Each station provides access to the network in a limited area, the area and configuration of which depends on the terrain and other parameters. Overlapping coverage areas create a honeycomb-like structure; from this image comes the term "cellular communication". When a subscriber moves, his phone is served by one or another base station, and switching (cell change) occurs in automatic mode, completely imperceptible to the subscriber, and does not affect the quality of communication in any way. This approach allows, using low-power radio signals, to cover large areas with a mobile communication network, which provides this type of communication, in addition to efficiency, also a high level of environmental friendliness.

The operating company not only technically provides mobile communications, but also enters into economic relations with subscribers who purchase from it a certain set of basic and additional services. Since there are a lot of types of services, prices for them are combined into sets called tariff plans. The billing system (software and hardware system that keeps records of the services provided to the subscriber) is responsible for calculating the cost of services rendered to each subscriber.

The operator's billing system interacts with similar systems of other companies, for example, those providing the subscriber with roaming services (the ability to use mobile communications in other cities and countries). All mutual settlements for mobile communication, including roaming, the subscriber makes with his operator, which is a single settlement center for him.

Roaming - access to mobile services outside the network coverage area of ​​the "home" operator with which the subscriber has a contract.

While roaming, the subscriber usually keeps his telephone number, continues to use his cell phone, making and receiving calls in the same way as in home network. All actions necessary for this, including inter-operator traffic exchange and attraction, as necessary, of the resources of other communication companies (for example, those providing transcontinental communications), are performed automatically and do not require additional actions from the subscriber. If the home and guest networks provide communication services in different standards, roaming is still possible: a subscriber can be given another device for the duration of the trip, while keeping his phone number and automatically routing calls.

History of cellular communication.

Work on the creation of civilian mobile communication systems began in the 1970s. By this time, the development of conventional telephone networks in European countries had reached such a level that the next step in the evolution of communications could only be the availability of telephone communications everywhere and everywhere.

Networks on the first civil cellular standard - NMT-450 - appeared in 1981. Although the name of the standard is an abbreviation of the words Nordic Mobile Telephony (“mobile telephony of the northern countries”), the first cellular network on the planet was deployed in Saudi Arabia. In Sweden, Norway, Finland (and other Nordic countries), NMT networks went online a few months later.

Two years later, in 1983, the first AMPS network was launched in the United States ( Advanced Mobile Phone Service), created at the Bell Laboratories research center.

The NMT and AMPS standards, which are commonly referred to as the first generation of cellular communication systems, provided for the transmission of data in analog form, which did not allow for the proper level of noise immunity and protection against unauthorized connections. Subsequently, they had modifications improved through the use of digital technologies, for example, DAMPS (the first letter of the abbreviation owes its appearance to the word Digital - “digital”).

The second generation standards (the so-called 2G) - GSM, IS-95, IMT-MC-450, etc., originally created on the basis of digital technologies, surpassed the first generation standards in terms of sound quality and security, and, as it turned out later, in terms of into the standard of development capability.

As early as 1982, the European Conference of Postal and Telecommunications Administrations (CEPT) set up a group to develop a single digital cellular standard. The brainchild of this group was GSM (Global System for Mobile Communications).

First GSM network was put into operation in Germany in 1992. Today, GSM is the dominant standard for cellular communication both in Russia and around the world. In 2004, over 90% of cellular subscribers served GSM networks in our country; in the world GSM was used by 72% of subscribers.

For the operation of GSM equipment, several frequency bands are allocated - they are indicated by numbers in the names. In the European region, GSM 900 and GSM 1800 are mainly used, in America - GSM 950 and GSM 1900 (at the time the standard was approved in the USA, “European” frequencies were occupied by other services there).

The popularity of the GSM standard was ensured by its significant features for subscribers:

– protection from interference, interception and "twins";

- the presence of a large number additional services;

- the ability, in the presence of "add-ons" (such as GPRS, EDGE, etc.), to provide data transfer from high speeds;

- the presence on the market of a large number telephone sets operating in GSM networks;

– simplicity of the procedure for changing one device to another.

In the process of development, cellular networks of the GSM standard acquired the possibility of expansion due to some "add-ons" over the existing infrastructure that provide high-speed data transmission. GSM networks with GPRS (General Packet Radio Service) support are called 2.5G, and GSM networks with support for the EDGE (Enhanced Data rates for Global Evolution) standard are sometimes called 2.75G networks.

In the late 1990s, third-generation (3G) networks appeared in Japan and South Korea. The main difference between the standards on which 3G networks are built and their predecessors is the enhanced capabilities of high-speed data transfer, which makes it possible to implement new services in such networks, in particular, video telephony. In 2002-2003, the first commercial 3G networks began to operate in some countries of Western Europe.

Although 3G networks currently exist only in a number of regions of the world, work is already underway in the engineering and technical laboratories of the largest companies to create standards for cellular communication. fourth generation. At the same time, not only a further increase in the data transfer rate is put at the forefront, but also an increase in the efficiency of using the bandwidth of the frequency bands allocated for mobile communications in order to access services for a large number of subscribers located in a limited area (which is especially important for megacities) .

Other mobile communication systems.

In addition to cellular communications, today there are other civil communication systems that also provide mobile communication via radio channels, but are built on different technical principles and are oriented to other subscriber terminals. They are less common than cell phones, but are used when cell phones are difficult, impossible, or uneconomical to use.

The DECT microcellular communication standard, which is used for communications in a limited area, is becoming increasingly popular. The base station of the DECT standard is capable of providing handsets (up to 8 of them can be serviced simultaneously) with each other, call forwarding, and also access to the telephone network common use. The potential of the DECT standard makes it possible to provide mobile communications within urban microdistricts, individual companies or apartments. They turn out to be optimal in regions with low-rise buildings, whose subscribers need only voice communication and can do without mobile transmission data and other additional services.

In satellite telephony, base stations are located on satellites in low Earth orbits. Satellites provide communications where the deployment of conventional cellular network impossible or unprofitable (at sea, in vast sparsely populated areas of tundra, deserts, etc.).

Trunking networks that provide subscriber terminals (they are usually called not telephones, but radio stations) communication within a certain territory are systems of base stations (repeaters) that transmit a radio signal from one terminal to another when they are at a considerable distance from each other. Since trunking networks usually provide communication to employees of departments (Ministry of Internal Affairs, Ministry of Emergency Situations, " Ambulance”, etc.) or on large technological sites (along highways, at a construction site, on the territory of factories, etc.), then trunking terminals do not have entertainment capabilities and design frills in design.

Wearable radios communicate with each other directly, without intermediate communication systems. Mobile communications of this type are preferred by both state (police, fire brigade, etc.) and departmental structures (for communications within a warehouse complex, parking lot or construction site), as well as private individuals (mushroom pickers, hunters-fishermen or tourists), in situations when it is easier and cheaper to use handheld radios than cellular phones to communicate with each other (for example, in remote areas where there is no cellular network coverage).

Paging provides receiving short messages to subscriber terminals - pagers. At present, paging communications in civil communications are practically not used; due to their limitations, they are pushed into the field of highly specialized solutions (for example, they serve to notify personnel in large medical institutions, transfer data to electronic information boards, etc.).

Since 2004, a new subspecies of mobile communications has become more and more widespread, providing the possibility of high-speed data transmission over a radio channel (in most cases, the Wi-Fi protocol is used for this). Areas with Wi-Fi coverage available for public use (paid or free) are called hotspots. Subscriber terminals in this case are computers - both laptops and PDAs. They can also provide two-way voice communication over the Internet, but this feature is used extremely rarely, the connection is mainly used to access the most common Internet services - e-mail, websites, instant messaging systems (such as ICQ), etc.

Where is mobile communication going?

In developed regions, the main direction in the development of mobile communications for the near future is convergence: providing subscriber terminals with automatic switching from one network to another in order to effective use capabilities of all communication systems. Saving money for subscribers and improving the quality of communication will allow automatic switching, for example, from GSM to DECT (and vice versa), with satellite communications to the "ground", and when providing wireless transmission data - between GPRS, EDGE, Wi-Fi and other standards, many of which (for example, WiMAX) are just waiting in the wings.

The place of mobile communications in the global economy.

Communications is the most dynamically developing branch of the world economy. But mobile communications, even in comparison with other areas of "telecom", are developing at a faster pace.

Back in 2003 total number mobile phones on the planet exceeded the number of stationary devices connected to wired public networks. In some countries, the number of mobile subscribers already in 2004 was higher than the number of inhabitants. This means that some people used more than one "mobile" - for example, two cell phones served by different carriers, or a phone for voice communication and a wireless modem for mobile access in Internet. In addition, more and more wireless communication modules were required to provide technological communications (in these cases, subscribers are not people, but specialized computers).

Currently, cellular operators provide full coverage of the territory of all economically developed regions of the planet, however, the extensive development of networks continues. New base stations are being installed to improve reception in places where the existing network cannot provide stable reception for some reason (for example, in long tunnels, in the metro area, etc.). In addition, cellular networks are gradually penetrating into low-income regions. The development of mobile communication technologies, accompanied by a sharp reduction in the cost of equipment and services, makes cellular services available to an increasing number of people on the planet.

The production of cell phones is one of the most dynamically developing areas of the high-tech industry.

The mobile phone service industry is also growing rapidly, offering accessories for personalizing devices: from original ringtones (ringtones) to key fobs, graphic screen savers, stickers on the case, interchangeable panels, covers and laces for carrying the device.

Phone types.

Cellular (mobile) phone - a subscriber terminal operating in a cellular network. In fact, each cell phone is a specialized computer that is focused primarily on providing (in the coverage area of ​​​​a home or guest network) voice communication of subscribers, but also supports text and multimedia messaging, is equipped with a modem and a simplified interface. Modern mobile phones provide voice and data transmission in digital form.

The earlier existing division of devices into "inexpensive", "functional", "business" and "image" models is increasingly losing its meaning - business devices acquire the features of fashion models and entertainment functions, as a result of the use of accessories cheap phones become fashionable, while the functionality of the fashionable ones is rapidly growing.

The miniaturization of tubes, which peaked in 1999-2000, was completed for quite objective reasons: the devices reached optimal size, their further reduction makes it inconvenient to press buttons, read text on the screen, etc. But the cell phone has become a real piece of art: to develop appearance devices attract leading designers, and the owners are given ample opportunities to personalize their devices on their own.

Currently, manufacturers pay special attention to the functionality of mobile phones, and as the main one (the time battery life, screens are being improved, etc.), and their additional features (digital cameras, voice recorders, MP3 players and other "related" devices are built into the devices).

Almost all modern devices, with the exception of some models of the lower price range, allow you to download programs. Most devices can run Java applications, and the number of phones using operating systems inherited from PDAs or ported from them is increasing: Symbian, Windows Mobile for Smartphones etc. Phones with built-in operating systems called smartphones (from a combination of the English words "smart" and "phone" - "smart phone").

Communicators can also be used as subscriber terminals today - pocket computers equipped with a module that supports GSM / GPRS, and sometimes EDGE and third-generation standards.

Non-voice services of cellular networks.

Available to subscribers of cellular networks whole line non-voice services, the “range” of which depends on the capabilities of a particular phone and on the range of offers of the operator company. The list of services in the home network may differ from the list of services available in roaming.

Services can be communication (providing various forms of communication with other people), informational (for example, reporting on weather forecasts or market quotes), providing Internet access, commercial (for paying for various goods and services from phones), entertainment ( mobile games, quizzes, casinos and lotteries) and others (this includes, for example, mobile positioning). Today, there are more and more services that are "at the junction", for example, most games and lotteries are paid, there are games that use mobile positioning technologies, etc.

Almost all operators and most modern devices support the following services:

– SMS – Short Message Service – transmission of short text messages;

– MMS – Multimedia Messaging Service – transmission of multimedia messages: photos, videos, etc.;

– automatic roaming;

– identification of the caller's number;

– ordering and receiving various means of personalization directly via cellular communication channels;

– access to the Internet and viewing specialized (WAP) sites;

- downloading ringtones, pictures, information materials from specialized resources;

– data transfer using the built-in modem (it can be carried out using various protocols, depending on which technologies are supported by a particular device).

Mobile communications in Russia.

There were no civilian mobile communication systems in the USSR. With some stretch, “civilian” can be called the Altai mobile telephony system, built on the basis of the MRT-1327 standard, which at the turn of the 1970s and 80s was created to provide communications for representatives of the party, state and economic leadership. "Altai" is successfully operated to this day. Of course, it cannot compete with cellular networks, but it finds application for solving some highly specialized tasks: providing communications for mobile units of urban emergency services, installing telephones in summer cafes, etc.

The first commercial cellular networks built according to the NMT standard were created in Russia in the autumn of 1991. The pioneers of mobile telephony in our country were Delta Telecom (St. Petersburg) and Moscow Cellular Communications. The first cell phone call was made on September 9, 1991 in St. Petersburg: Anatoly Sobchak, then the mayor of the city, called his colleague, the mayor of New York.

In July 1992, the first calls were made to the BeeLine AMPS network.

The first Russian GSM network, created by MTS, began connecting subscribers in July 1994.

In 2005, there are three federal mobile operators in Russia that provide services in the GSM standard: MTS, BeeLine and MegaFon. The range and quality of the telecommunications services they offer, as well as their prices, are about the same. By 2005, the number of base stations in the networks of the leading metropolitan operators in Moscow and the Moscow suburbs was about 3,000, and the coverage area exceeded that of most European countries. In addition to them, numerous local operators exist and work quite effectively - both subsidiaries of the "Big Three" and independent companies.

Operators are actively developing the market by increasing the coverage of their networks and popularizing mobile communications among various segments of the population. If in the mid-1990s a cell phone was available only to representatives of the wealthiest segments of the population, today almost everyone can use mobile communications. Russian operators implement the latest services in their networks and offer services built on their basis, often even ahead of most European companies. At present, all three federal GSM operators are preparing for the deployment of 3G commercial networks.

In addition to GSM networks of federal and local mobile operators, networks of other standards continue to be used in Russia: DAMPS, IS-95, NMT-450, DECT and IMT-MC-450. The latter standard has the status of a federal one, and the networks built on its basis (for example, SkyLink) are developing very actively. However, neither in terms of coverage area, nor in terms of the number of subscribers served, networks of all standards other than GSM cannot create significant competition for the top three federal operators.

Literature:

Malyarevsky A., Olevskaya N. Your mobile phone(popular tutorial). M, "Peter", 2004
Zakirov Z.G., Nadeev A.F., Faizullin R.R. Cellular communication of the GSM standard. Current state, transition to third generation networks("MTS Library"). M., Eco-Trends, 2004
Popov V.I. Basics of GSM cellular communication("Engineering Encyclopedia of the Fuel and Energy Complex"). M., Eco-Trends, 2005



Do you know what happens after you dial a friend's number on your mobile phone? How does the cellular network find it in the mountains of Andalusia or on the coast of distant Easter Island? Why does the conversation sometimes suddenly stop? Last week I visited Beeline and tried to figure out how cellular communication works ...

A large area of ​​the populated part of our country is covered by Base Stations (BS). In the field, they look like red and white towers, and in the city they are hidden on the roofs of non-residential buildings. Each station picks up a signal from mobile phones at a distance of up to 35 kilometers and communicates with a mobile phone via service or voice channels.

After you dialed a friend's number, your phone contacts the nearest Base Station (BS) via a service channel and asks you to allocate a voice channel. The base station sends the request to the controller (BSC), which forwards it to the switch (MSC). If your friend is on the same cellular network, the switch will check the Home Location Register (HLR) to find out where in this moment the called subscriber is located (at home, in Turkey or in Alaska), and will transfer the call to the appropriate switchboard, from where it will forward it to the controller and then to the Base Station. The Base Station will contact the mobile phone and connect you with a friend. If your friend is a subscriber of another network or you call a landline phone, then your switch will contact the corresponding switch of another network. Difficult? Let's take a closer look. The Base Station is a pair of iron cabinets locked in a well-air-conditioned room. Given that in Moscow it was +40 on the street, I wanted to live in this room for a while. Usually, the Base Station is located either in the attic of the building or in a container on the roof:

2.

The Base Station antenna is divided into several sectors, each of which "shines" in its own direction. The vertical antenna communicates with phones, the round one connects the Base Station with the controller:

3.

Each sector can serve up to 72 calls at the same time, depending on the setup and configuration. A Base Station can consist of 6 sectors, so one Base Station can serve up to 432 calls, however, there are usually fewer transmitters and sectors installed in the station. Cellular operators prefer to install more BS to improve the quality of communication. The Base Station can operate in three bands: 900 MHz - the signal at this frequency spreads further and penetrates better inside buildings 1800 MHz - the signal spreads over shorter distances, but allows you to install more transmitters on 1 sector 2100 MHz - 3G Network This is how the cabinet looks like with 3G equipment:

4.

900 MHz transmitters are installed at Base Stations in fields and villages, and in the city, where Base Stations are stuck like needles in a hedgehog, communication is mainly carried out at a frequency of 1800 MHz, although transmitters of all three bands can be present at any Base Station at the same time.

5.

6.

A 900 MHz signal can reach up to 35 kilometers, although the "range" of some Base Stations along the routes can reach up to 70 kilometers, by reducing the number of simultaneously served subscribers at the station by half. Accordingly, our phone, with its small built-in antenna, can also transmit a signal up to 70 kilometers... All Base Stations are designed to provide optimum ground level radio coverage. Therefore, despite the range of 35 kilometers, the radio signal is simply not sent to the altitude of the aircraft. However, some airlines have already begun installing low-powered base stations on their aircraft that provide coverage inside the aircraft. Such a BS is connected to the terrestrial cellular network using satellite channel. The system is complemented by a control panel that allows the crew to turn the system on and off, as well as certain types of services, such as turning off the voice on night flights. The phone can measure signal strength from 32 Base Stations simultaneously. It sends information about the 6 best (by signal level) over the service channel, and the controller (BSC) decides which BS to transmit current call(Handover) if you are on the move. Sometimes the phone can make a mistake and transfer you to the BS with worst signal, in which case the conversation may be interrupted. It may also turn out that at the Base Station that your phone has selected, all voice lines are busy. In this case, the conversation will also be interrupted. I was also told about the so-called "top floor problem". If you live in a penthouse, then sometimes, when moving from one room to another, the conversation may be interrupted. This is because in one room the phone can "see" one BS, and in the second - another, if it goes to the other side of the house, and, at the same time, these 2 Base Stations are at a great distance from each other and are not registered as " neighboring" mobile operator. In this case, the transfer of a call from one BS to another will not occur:

Communication in the metro is provided in the same way as on the street: Base Station - controller - switch, with the only difference that small Base Stations are used there, and in the tunnel coverage is provided not by an ordinary antenna, but by a special radiating cable. As I wrote above, one BS can make up to 432 calls at the same time. Usually this power is enough for the eyes, but, for example, during some holidays, the BS may not be able to cope with the number of people who want to call. This usually happens on New Year when everyone starts to congratulate each other. SMS are transmitted through service channels. On March 8 and February 23, people prefer to congratulate each other via SMS, sending funny rhymes, and phones often cannot agree with the BS on the allocation of a voice channel. I was told an interesting story. From one district of Moscow, complaints began to come from subscribers that they could not get through anywhere. Technicians began to understand. Majority voice channels was free, and all the staff were occupied. It turned out that next to this BS there was an institute where exams were taking place and students were constantly exchanging text messages. The phone divides long SMS into several short ones and sends each one separately. Employees of the technical service are advised to send such congratulations using MMS. It will be faster and cheaper. From the Base Station, the call goes to the controller. It looks as boring as the BS itself - it's just a set of cabinets:

7.

Depending on the equipment, the controller can serve up to 60 Base Stations. Communication between the BS and the controller (BSC) can be carried out via a radio relay channel or via optics. The controller controls the operation of radio channels, incl. controls the movement of the subscriber, signal transmission from one BS to another. The switch looks much more interesting:

8.

9.

Each switch serves from 2 to 30 controllers. It already occupies a large hall filled with various cabinets with equipment:

10.

11.

12.

The switch performs traffic control. Remember the old movies where people first called the “girl”, and then she connected them with another subscriber, rewiring the wires? Modern switches do the same:

13.

To control the network, Beeline has several cars, which they affectionately call "hedgehogs". They move around the city and measure the signal level of their own network, as well as the level of the network of colleagues from the "Big Three":

14.

The entire roof of such a car is studded with antennas:

15.

Inside there is equipment that makes hundreds of calls and captures information:

16.

Round-the-clock control over switches and controllers is carried out from the Mission Control Center of the Network Control Center (NCC):

17.

There are 3 main areas for monitoring the cellular network: accident rate, statistics and feedback from subscribers. Just like in airplanes, all cellular network equipment has sensors that send a signal to the MCC and output information to the dispatchers' computers. If some equipment is out of order, then the light on the monitor will “blink”. The MSC also keeps track of statistics for all switches and controllers. He analyzes it by comparing it with previous periods (hour, day, week, etc.). If the statistics of one of the nodes began to differ sharply from the previous indicators, then the light on the monitor will again begin to “blink”. Feedback accepted by subscriber service operators. If they cannot solve the problem, then the call is transferred to a technical specialist. If he turns out to be powerless, then an “incident” is created in the company, which is solved by engineers involved in the operation of the corresponding equipment. The switches are monitored around the clock by 2 engineers:

18.

The graph shows the activity of Moscow switches. It is clearly seen that almost no one calls at night:

19.

Control over the controllers (sorry for the tautology) is carried out from the second floor of the Network Control Center:

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21.

Cellular communication is considered one of the most useful inventions of mankind - along with the wheel, electricity, the Internet and the computer. And in just a few decades, this technology has experienced a number of revolutions. How wireless communication began, how cells work and what opportunities the new mobile standard will open 5G?

The first use of mobile phone radio dates back to 1921 when the US Detroit police used one-way dispatch communication in the 2 MHz band to transmit information from a central transmitter to receivers in police cars.

How did the cell phone come about

For the first time, the idea of ​​cellular communication was put forward in 1947 - engineers from Bell Labs Douglas Ring and Ray Young worked on it. However, the real prospects for its implementation began to emerge only by the beginning of the 1970s, when the company's employees developed a working architecture for the cellular communication hardware platform.

So, American engineers suggested placing transmitting stations not in the center, but at the corners of the "cells", and a little later a technology was invented that allows subscribers to move between these "cells" without interrupting communication. After that, it remains to develop operating equipment for such a technology.

Motorola successfully solved the problem - its engineer Martin Cooper demonstrated the first working prototype of a mobile phone on April 3, 1973. He called the head of the research department of a competitor company right off the street and told him about his own successes.

Motorola's management immediately invested $100 million in the promising project, but the technology entered the commercial market only ten years later. This delay is due to the fact that at first it was required to create a global infrastructure of cellular base stations.

In the United States, AT&T took over this work - the telecommunications giant obtained licensing from the federal government of the necessary frequencies and built the first cellular network that covered the largest American cities. The famous Motorola DynaTAC 8000 was the first mobile phone.

The first cell phone went on sale on March 6, 1983. It weighed almost 800 grams, could work on a single charge for 30 minutes of talk time and charged for about 10 hours. At the same time, the device cost $ 3,995 - a fabulous amount at that time. Despite this, the mobile phone instantly became popular.

Why is it called cellular

The principle of mobile communication is simple - the territory on which the connection of subscribers is provided is divided into separate cells or "cells", each of which is served by a base station. At the same time, in each "cell" the subscriber receives identical services, so he himself does not feel the crossing of these virtual boundaries.

Typically, a base station in the form of a pair of iron cabinets with equipment and antennas is placed on a specially built tower, but in the city they are often placed on the roofs of high-rise buildings. On average, each station catches a signal from mobile phones at a distance of up to 35 kilometers.

To improve the quality of service, operators are also installing femtocells - low-power and miniature cellular communication stations designed to serve a small area. They allow you to dramatically improve coverage in those places where it is needed. Cellular communications in Russia will be combined with space

A mobile phone on the network listens to the air and finds a signal from the base station. In addition to the processor and RAM, a modern SIM card has a unique key sewn into it that allows you to log in to the cellular network. Communication between the phone and the station can be carried out using different protocols - for example, digital DAMPS, CDMA, GSM, UMTS.

Cellular networks of different operators are connected to each other, as well as to the fixed telephone network. If the phone leaves the coverage area of ​​the base station, the device establishes communication with others - the connection established by the subscriber is imperceptibly transmitted to other "cells", which ensures continuous communication when moving.

In Russia, three bands are certified for broadcasting - 800 MHz, 1800 MHz and 2600 MHz. The 1800 MHz band is considered the most popular in the world, as it combines high capacitance, long range and high penetrating power. It is in it that most mobile networks now work.

What mobile communication standards are

The first mobile phones worked with 1G technologies - this is the very first generation of cellular communications, which relied on analog telecommunication standards, the main of which was NMT - Nordic Mobile Telephone. It was intended exclusively for the transmission of voice traffic.

By 1991, the birth of 2G is attributed - the main standard of the new generation has become GSM (Global System for Mobile Communications). This standard is still supported today. Communication in this standard has become digital, it has become possible to encrypt voice traffic and send SMS.

The data transfer rate within GSM did not exceed 9.6 kbps, which made it impossible to transmit video or high-quality sound. The GPRS standard, known as 2.5G, was intended to solve the problem. For the first time, he allowed mobile phone owners to use the Internet.

This standard has already provided data transfer rates up to 114 Kbps. However, it soon also ceased to satisfy the ever-increasing demands of users. To solve this problem, the 3G standard was developed in 2000, which provided access to Internet services at a data transfer rate of 2 Mbps.

Another difference with 3G was the assignment of an IP address to each subscriber, which made it possible to turn mobile phones into small computers connected to the Internet. The first commercial 3G network was launched on October 1, 2001 in Japan. In the future, the throughput of the standard has been repeatedly increased.

The most modern standard is fourth-generation 4G communication, which is intended only for high-speed data transfer services. Bandwidth 4G networks are capable of reaching 300 Mbps, which gives the user almost unlimited opportunities to surf the Internet.

Cellular communication of the future

The 4G standard is designed for the continuous transmission of gigabytes of information, it does not even have a channel for voice transmission. Due to extremely efficient multiplexing schemes, downloading a high-definition movie on such a network will take the user 10-15 minutes. However, even its capabilities are already considered limited.

In 2020, the official launch of a new generation of 5G communications is expected, which will allow the transfer of large amounts of data at ultra-high speeds up to 10 Gbps. In addition, the standard will allow connecting up to 100 billion devices to high-speed Internet.

It is 5G that will allow the real Internet of Things to appear - billions of devices will exchange information in real time. According to experts, network traffic will soon grow by 400%. For example, cars will be constantly on the global network and receive traffic data.

Low latency will ensure real-time communication between vehicles and infrastructure. A reliable and always-on connection is expected to open the way for the first time to launch fully autonomous vehicles on the roads.

Russian operators are already experimenting with new specifications - for example, Rostelecom is working in this direction. The company signed an agreement on the construction of 5G networks in the Skolkovo innovation center. The implementation of the project is included in the state program "Digital Economy", recently approved by the government.