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 does something that we are all used to for a long time work and work? Are signals from base stations transmitted via wires or does it all work somehow differently? 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 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 observed 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 boxes of gray color, from which various antennas (usually up to 12 antennas) stick out in different directions. The antennas here work both for reception and transmission, and they belong to the cellular operator. The base station antennas are directed to all possible directions (sectors) to provide “network coverage” to subscribers from all directions at a distance of up to 35 kilometers.
An antenna of one sector is able to simultaneously serve up to 72 calls, 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 with a cable to the control unit of the base station. And already blocks of several base stations (each station serves its 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 into buildings and structures, spreads further, therefore, it is this band that is often used in villages and in the fields; the signal at a frequency of 1800 MHz does not spread so far, but more transmitters are installed in one sector, therefore, in cities such stations are more often installed; finally 2100 MHz is a 3G network.
There can be several controllers, of course, in a settlement or area, 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 ordinary telephone communication, long-distance communication and international communication. If the network is small, then one switch is sufficient; if the network is large, two or more switches are used. Switches are connected together by wires.
In the process of moving a person talking on a mobile phone along the street, for example: he is walking, riding in public transport, or moving in a private car - his phone should not lose the network for a moment, the conversation should not be interrupted.
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 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 associated 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-layered network scheme to reduce the likelihood of equipment failure. A multi-level network is built as follows: cell phone - base station - controller - switch.
Let's say we make a call, and now the signal has already reached the switchboard. The switch transmits our call to 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 switchboard, which is located on the side of the subscriber receiving the call (called by us). The "receiving" switch already has data about where the called subscriber is located, in which network coverage area: which controller, which base station. And so, the network poll starts from the base station, the addressee is found, and his phone “receives a call”.
The entire chain of described events, from the moment the number is dialed to the moment the call rang out on the receiving side, usually lasts no more than 3 seconds. So we can call anywhere in the world today.
Andrey Povny
15.09.2011
The history of the formation and development of mobile communications in Russia and the world
When I started thinking about the idea of an article about the past of cellular communications, the first thing I remembered was the story of April 3, 1973. It was on this day that Martin Cooper, head of the mobile communications division of the American company Motorola, made the world's first mobile phone call. And it is this date that is considered the birthday of mobile communications in the form in which we are all accustomed to it. But it all started much earlier.
When people talk about the history of cellular communications, the first thing to remember is April 3, 1973. It was on this day that Martin Cooper, head of the mobile communications division of the American company Motorola, made the world's first mobile phone call. And now it is considered the birthday of mobile communications in the form we are used to. But her story began much earlier.
The beginning of the way
Probably the first and most important date in the history of mobile communications should be considered May 7, 1895, when the famous Russian scientist Alexander Stepanovich Popov demonstrated a device designed to register electromagnetic waves. Interestingly, initially Popov did not plan to create any means of radio communication, but developed a "lightning detector", a device for registering lightning. But, in fact, Popov's device became the world's first radio receiver, the signal source for which was lightning discharges. Later, in September 1895, instead of a metrological recorder, Popov connected a Morse telegraph to his "lightning detector", which brought him even closer to a means for wireless information transmission.
The next step towards mobile communications was the wireless telegraph sessions conducted by Guglielmo Marconi. Moreover, if in 1896 information was transmitted over a distance of several kilometers, then by the end of 1901 Marconi's message was received on the other side of the Atlantic Ocean. The fact that Marconi had a commercial streak also played a role, thanks to which the technology he developed became commercially successful, and the company "Marconi & Co." - known all over the world.
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Popov's "lightning detector" is the device that started
wireless radio
No less important was the transition from the use of abstract "dots-dashes" to the transmission of a living human voice. For researchers-radio engineers of those years, this was one of the most urgent problems, in the process of solving which hundreds of studies were carried out and dozens of patents were obtained. But the greatest success was achieved by Reginald Fessenden, who in 1900 for the first time transmitted voice over the radio channel, and by 1903 received its quite acceptable quality. The date of the "mobilization" of wireless radio communication was 1901, when Marconi installed a transceiver on a Tonicroft steam car.
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This is what the first car looked like,
mobile radio
The next key year was 1921, when the world's first mobile telegraph dispatch system was launched in the American Detroit, intended for the needs of the local police. The exchange of information was one-way - having received a signal (in Morse code), the police contacted the station using a regular phone. In fact, the system built in Detroit was the prototype of the paging communication, already forgotten by many. Two-way mobile radio communications for police assistance appeared in 1933 in New York. Moreover, it was no longer telegraphic, but voice, although it operated in half-duplex mode, i.e. to switch between reception and transmission, you had to press a button.
America and Europe
For private customers, mobile radio communications first became available on June 17, 1946, when AT&T and Bell Telephone Laboratories joint efforts of AT&T and Bell Telephone Laboratories launched an MTS network operating at a frequency of 150 MHz in St. Louis (Missouri), USA. The principle of operation of the MTS network was different from modern mobile communications - one powerful transmitter was used to cover a certain area, and a network of receivers was used to register the signal from subscriber devices. Calling in the MTS network was carried out in manual mode - at first, the subscriber chose a free channel, and then established a connection with the operator who connected him with the desired subscriber. Moreover, initially the MTS network worked in half-duplex mode, which made it possible to solve the echo problem. Full duplex mode (ie, as in a regular telephone) and automatic channel selection appeared only in 1964. By the way, by the end of the 40s. AT&T and Bell Telephone Laboratories of the last century were not the most advanced - in 1948 the Richmond Radiotelephone Company (Indiana) launched a fully automatic mobile radio system in which a subscriber was called without the help of an operator.
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One of the first car radiotelephones
All the first mobile radio communication systems of those years had a serious limitation in the form of a frequency resource with a limited number of channels. This prevented the provision of full coverage of a large area and did not allow two networks to operate in the same frequency range - the minimum distance between two radio systems had to be at least 100 km. A solution to this problem was found by an employee of Bell Laboratories D. Ring, who proposed to divide the entire coverage area into cells (cells) formed by base stations operating in different frequency ranges. And it is the cellular principle that has become fundamental for modern mobile networks. The practical implementation of the idea appeared in 1969 in Metroliner trains running between New York and Washington - the entire train route (255 miles) was divided into nine zones, each of which had six channels at a frequency of 450 MHz, and the control center the system was in Philadelphia.
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Schematic representation of a cellular network
Simultaneously with the United States, mobile radio communication systems were developing in Europe, where the main work was carried out by the companies "Ericsson" and "Marconi". The first tests of European radio communication systems took place in 1951, and the Japanese ones - in 1967. By the way, it was the Japanese who found that in the conditions of urban development, the bands in the region of 400 and 900 MHz are most suitable for mobile radio communication. Among European countries, the first commercially successful cellular network was deployed in Finland in 1971, and by 1978 it covered the entire country. Naturally, the talk was about automobile radio communication, which was even reflected in its name - Autoradiopuhelin (ARP, "Automobile radiotelephone"). The Autotel network was positioned similarly. However, despite the analogue voice transmission, in the Autotel standard, all service information, unlike other mobile radio communication systems of those years, was already transmitted in digital form.
There were developments in the field of mobile radio communications in our country, but they will be discussed a little later, but for now let's return to the United States, where a fierce struggle unfolded between AT&T Bell Labs and Motorola, who were striving to become leaders in the emerging mobile communications market. Moreover, AT&T Bell Labs relied on car radios, and Motorola - on compact devices that you could carry with you. The competition was quite tough, even attempts were made to use the administrative resource represented by the FCC (Federal Communications Commission). Motorola emerged victorious in the struggle, and the main direction for the further development of mobile communications was the creation of compact devices that could simply be carried with you. A commercial network based on Motorola's proposed principles was launched in 1983, a decade after that historic call.
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Motorola's first mobile phone DynaTAC 8000X
(Dynamic adaptive total area coverage)
If we discuss the cellular communication standards of those years, it should be recalled that in America, the analogue standard AMPS (Advanced mobile phones service) began to gain popularity, later upgraded to digital D-AMPS. In Europe, a whole scattering of various incompatible standards has appeared, and the most widespread are the Scandinavian NMT (Nordic mobile telephony) and the TACS (Total access communications system, analogue of AMPS) deployed in a number of European countries. In Japan, the most popular are NTT (Nippon telephone and telegraph system) and a modified version of TACS called JTACS (NTACS). All of these standards, like AMPS, were analog, and the networks built belonged to the first generation of mobile communications.
Simultaneously with the growth in the number of subscribers to mobile networks, the Europeans faced the question of creating a unified standard for mobile communications, for which in 1982 the Groupe Spécial Mobile group was created, which included 26 European telephone companies. It took nine years to develop the eponymous standard - its first specification was published in 1991, and the world's first commercial GSM network was launched in 1992 in Finland. An alternative to GSM has become the CDMA standard, which is widespread in the USA and Asian countries. The first commercial CDMA network appeared in 1995 in Hong Kong, and the first satellite communication system for commercial purposes (based on CDMA Omni TRACKC technology) was launched in 1980. By the way, the theoretical foundations of CDMA were laid back in 1935 by Russian scientist D.V. Ageev.
our history
Cellular communication in the modern sense came to our country in 1991, when Delta Telecom deployed a network of the NMT-450i standard, and the first call with its use took place on September 9, 1991. The first Russian GSM network was launched in 1994. , simultaneously with the emergence of the operator "North-West GSM".
However, the history of the development of mobile communications in our country has deeper roots. It all started with the fact that during the Great Patriotic War, the Soviet scientist Georgy Ilyich Babat proposed the idea of a device called "monophone", which was a portable telephone set operating completely in automatic mode. The operating frequency range of the device was supposed to be in the region of 1-2 GHz, but unlike modern cellular communications, it was planned to use not a radio channel for voice transmission in a "monophone", but an extensive network of waveguides.
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G.I. Babat, the inventor of the "monophone"
The next step towards domestic mobile communication was made by G. Shapiro and I. Zakharchenko, who in 1946 proposed a system of automobile radiotelephone communication. Its principle was simple and ingenious - city telephone exchanges were supposed to be supplemented with radio receiving equipment, and individual callsigns were to be assigned to each car equipped with radio communication. To make a call, it was enough to broadcast your callsigns, after which the telephone installed in the car was automatically turned on, which could be used like an ordinary telephone. When an incoming call came to the mobile subscriber's number, communication with him was also carried out by means of callsigns. At first, even the range of the Shapiro-Zakharchenko system was about 20 km, but later the inventors were able to increase it to 150 km, and the device itself was very compact. Initially, the Shapiro-Zakharchenko system was supposed to be used to coordinate the work of the police, firefighters, doctors and other emergency services. However, the idea did not take root primarily due to the reluctance of these services to be tied to the city telephone network.
But really sensational can be considered the fact that in 1957 L. I. Kupriyanovich created a prototype of a mobile phone, named LK-1. Interestingly, before the development of the LK-1, Kupriyanovich's field of activity was the creation of portable radios, just like his overseas colleague Martin Cooper. The LK-1 was interfaced with the city telephone network through the "Automatic Telephone Radio Station" (ATR), with which the "mobile" handset was connected by four frequency channels: sound reception, sound transmission, transmission of dialing signals and sending a call completion signal. Moreover, the issue of mass use of LK-1 was also thought out - in this case, the control signals differed in tonality, and different frequency channels were used for voice transmission. The range of the device was several tens of kilometers.
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Note in the journal "Science and Life", No. 10, 1958
Pay attention - in the USSR, initially, the stake was made precisely on the creation of mobile radio communication systems, the use of which is as close as possible to the use of ordinary city phones, and these systems should have been as simple as possible to integrate with the existing city telephone network. The importance of compact dimensions was also understood - if the first versions of the LK-1 weighed about 3 kg (remember, the weight of automobile radiotelephones was 10-20 kg), then already in 1958 Kupriyanovich managed to make a phone weighing only 500 grams. And in 1959 he put forward a proposal to establish the APR on a high-altitude mission, i.e. implement the same thing that Martin Cooper did 14 years later. But the invention of L.I. Kupriyanovich did not receive the move, and by 1960-1961. in his articles, he talks about walkie-talkies and electronics news, but does not mention a word about the radiotelephone.
And this is no coincidence - at the end of the 50s. of the last century, by order of the country's top leadership, the development of the Altai mobile automatic radio communication system began in the USSR. Moreover, one of the main requirements was that its use was as similar as possible to the use of a conventional telephone network, i.e. manual channel switching and the need to call a dispatcher were eliminated. And this task was solved - already in 1963 the system was put into trial operation on the territory of Moscow. Altai's operating range was in the region of 150 MHz, and later the 330 MHz range was also involved. By the mid-70s, 114 cities of the USSR were already covered by this system, and at the 1980 Olympics it became the main means of communication for journalists covering it. Moreover, the quality of communication on Altai was not worse than on the best wire telephone lines, and problems with communication arose quite rarely. In the era of its heyday, it became available not only to party and state leaders, but also to heads of enterprises - by the beginning of the 80s. it was used by about 25 thousand subscribers. For the top leadership of the country and the needs of the special services, "Rosa" was also created, which was a variant of "Altai", supplemented with encryption means.
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Subscriber equipment "Altai" of the 1960s
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The USSR also had plans to deploy a mobile communications network available to the average person. In the early 1980s, work began on the VoLeMoT system, the name of which consisted of the first letters of the cities where it was developed: Voronezh, Leningrad, Molodechno, Ternopil. Moreover, the system initially included the possibility of using multiple base stations in order to cover the entire territory of the country and support for automatic transition between base stations without interrupting the conversation. Thus, VoLeMoT could become a full-fledged cellular network, and if it were not for bureaucratic delays and insufficient funding for work, it would have been launched by the mid-1980s. It was planned to use the frequency of 330 MHz as the operating range in it, which made it possible to cover long distances with one base station. By the way, the system was put into operation in some cities, but this happened only in the mid-1990s, when technological leadership was lost, and the market was dominated by NMT and GSM networks.
Summary
History has no subjunctive mood. We missed the opportunity to become leaders in the construction of mobile networks, but our country had a chance for this. In 1959, the Bulgarian scientist Hristo Bachvarov created a mobile phone, conceptually similar to the apparatus of L.I. Kupriyanovich, and received the corresponding patent. Moreover, at the Interorgtechnika-66 exhibition, PAT-0.5 and ATRT-0.5, compact mobile phones of industrial production, as well as the RATTs-10 base station, capable of simultaneously connecting six mobile subscribers to the city telephone network, were lit up at the Interorgtechnika-66 exhibition. But all these developments did not go into series, and everyone recognized the birthday of mobile communications on April 3, 1973, when Martin Cooper made his historic call.
How the connection was born
Cellular communication has recently become so firmly established in our daily life that it is difficult to imagine modern society without it. Like many other great inventions, the mobile phone has greatly influenced our life, and in many of its areas. It is difficult to say what the future would be like if it were not for this convenient form of communication. Probably the same as in the movie "Back to the Future-2", where there are flying cars, hoverboards, and much more, but no cellular connection!
But today in a special report for there will be a story not about the future, but about how modern cellular communication is arranged and works.
In order to learn about the work of modern cellular communication in the 3G / 4G format, I asked to visit the new federal operator Tele2 and spent a whole day with their engineers, who explained to me all the details of data transmission through our mobile phones.
But first, I'll tell you a little about the history of the emergence of cellular communications.
The principles of wireless communication were tested almost 70 years ago - the first public mobile radiotelephone appeared in 1946 in St. Louis, USA. In the Soviet Union, a prototype of a mobile radiotelephone was created in 1957, then scientists from other countries created similar devices with different characteristics, and only in the 70s of the last century in America the modern principles of cellular communication were determined, after which its development began.
Martin Cooper - the inventor of the prototype of the portable cell phone Motorola DynaTAC weighing 1.15 kg and dimensions 22.5x12.5x3.75 cm
If in Western countries, by the mid-90s of the last century, cellular communication was widespread and used by most of the population, in Russia it had just begun to appear, and became available to everyone a little over 10 years ago.
Bulky brick-like mobile phones that worked in the first and second generation formats have gone down in history, giving way to smartphones with 3G and 4G, better voice communication and high Internet speed.
Why is the connection called cellular? Because the territory in which communication is provided is divided into separate cells or cells, in the center of which base stations (BS) are located. In each "cell" the subscriber receives the same set of services within certain territorial boundaries. This means that moving from one "cell" to another, the subscriber does not feel territorial attachment and can freely use communication services.
It is very important that there is continuity of the connection when moving. This is ensured thanks to the so-called handover, in which the connection established by the subscriber is, as it were, picked up by neighboring cells on the relay, and the subscriber continues to talk or dig in social networks.
The entire network is divided into two subsystems: a base station subsystem and a switching subsystem. Schematically, it looks like this:
In the middle of a "cell", as mentioned above, there is a base station, which usually serves three "cells". The radio signal from the base station is emitted through 3 sector antennas, each of which is directed to its own "cell". It so happens that several antennas of one base station are directed to one "cell" at once. This is due to the fact that the cellular network operates in several bands (900 and 1800 MHz). In addition, this base station may have equipment of several generations of communication (2G and 3G) at once.
But on the BS Tele2 towers there is only equipment of the third and fourth generation - 3G / 4G, since the company decided to abandon old formats in favor of new ones, which help to avoid interruptions in voice communication and provide a more stable Internet. Regulars of social networks will support me in the fact that nowadays Internet speed is very important, 100-200 kb / s is not enough anymore, as it was a couple of years ago.
The most common location for the BS is a tower or mast built specifically for it. Surely you could see the red and white BS towers somewhere far from residential buildings (in a field, on a hill), or where there are no tall buildings nearby. Like this one that is visible from my window.
However, in urban areas it is difficult to find a place for a massive structure. Therefore, in large cities, base stations are located on buildings. Each station picks up a signal from mobile phones at a distance of up to 35 km.
These are antennas, the BS equipment itself is located in the attic, or in a container on the roof, which is a pair of iron cabinets.
Some base stations are located where you wouldn't even guess. Like on the roof of this parking lot.
The BS antenna consists of several sectors, each of which receives / sends a signal in its own direction. If the vertical antenna communicates with telephones, then the round antenna connects the BS to the controller.
Depending on the characteristics, each sector can handle up to 72 calls simultaneously. The BS can consist of 6 sectors and serve up to 432 calls, however, usually fewer transmitters and sectors are installed at the stations. Cellular operators, such as Tele2, prefer to install more base stations to improve the quality of communication. As I was told, the most modern equipment is used here: Ericsson base stations, transport network - Alcatel Lucent.
From the base station subsystem, the signal is transmitted towards the switching subsystem, where the connection is established with the direction desired by the subscriber. The switching subsystem has a number of databases that store information about subscribers. In addition, this subsystem is responsible for security. To put it simply, the switch performs It has the same functions as the female operators who used to connect you with the subscriber by hand, only now all this happens automatically.
The equipment for this base station is hidden in this iron cabinet.
In addition to conventional towers, there are also mobile versions of base stations placed on trucks. They are very convenient to use during natural disasters or in crowded places (football stadiums, central squares) during holidays, concerts and various events. But, unfortunately, due to problems in the legislation, they have not yet found wide application.
To ensure optimal radio coverage at ground level, base stations are designed in a special way, therefore, despite the range of 35 km. the signal does not apply to the flight altitude of the aircraft. However, some airlines have already begun installing small base stations on their aircraft to provide cellular communications inside the aircraft. Such a BS connects to a terrestrial cellular network using a satellite link. 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, for example, turning off the voice on night flights.
I also looked into the Tele2 office to see how specialists control the quality of cellular communication. If a few years ago such a room would have been hung up to the ceiling with monitors showing network data (congestion, network failures, etc.), then over time the need for such a number of monitors has disappeared.
Technologies have developed greatly over time, and such a small room with several specialists is enough to monitor the operation of the entire network in Moscow.
Few views from the Tele2 office.
At a meeting of the company's employees, plans are being discussed to capture the capital) From the beginning of construction until today, Tele2 has managed to cover the whole of Moscow with its network, and is gradually conquering the Moscow region, launching more than 100 base stations weekly. Since I now live in the region, it is very important to me. so that this network would come to my town as quickly as possible.
The company plans for 2016 to provide high-speed communication in the metro at all stations, at the beginning of 2016 Tele2 communication is present at 11 stations: 3G / 4G communication at the Borisovo metro, Delovoy Tsentr, Kotelniki, Lermontovsky Prospekt , Troparevo, Shipilovskaya, Zyablikovo, 3G: Belorusskaya (Koltsevaya), Spartak, Pyatnitskoe shosse, Zhulebino.
As I said above, Tele2 abandoned the GSM format in favor of the third and fourth generation standards - 3G / 4G. This makes it possible to install 3G / 4G base stations with a higher frequency (for example, within the Moscow Ring Road, BSs stand at a distance of about 500 meters from each other) in order to provide more stable communication and high speed of mobile Internet, which was not the case in networks of previous formats.
From the company's office, I, in the company of engineers Nikifor and Vladimir, go to one of the points where they need to measure the communication speed. Nikifor stands opposite one of the masts on which communications equipment is installed. If you look closely, you will notice another such mast a little further on the left, with equipment from other cellular operators.
Oddly enough, but cellular operators often allow their competitors to use their tower structures to accommodate antennas (of course, on mutually beneficial terms). This is because building a tower or mast is expensive and can save you a lot of money!
While we were measuring the speed of communication, Nikifor several times passers-by grandmothers and uncles asked if he was a spy)) "Yes, we are jamming Radio Liberty!).
The equipment actually looks unusual, from its appearance you can assume anything.
The company's specialists have a lot of work, considering that in Moscow and the region the company has more than 7 thousand. base stations: of which about 5 thousand. 3G and about 2 thousand. base stations LTE, and recently the number of BS has increased by about a thousand more.
In just three months, 55% of the total number of new base stations of the operator in the region were put on the air in the Moscow region. At the moment, the company provides high-quality coverage of the territory where more than 90% of the population of Moscow and the Moscow region live.
By the way, in December the 3G Tele2 network was recognized as the best in quality among all metropolitan operators.
But I decided to personally check how good Tele2's connection is, so I bought a SIM card in the nearest shopping center on Voykovskaya metro station, with the simplest "Very black" tariff for 299 rubles (400 SMS / minutes and 4 GB). By the way, I had a similar Beeline tariff, which is 100 rubles more expensive.
I checked the speed on the spot. Reception - 6.13 Mbps, transmission - 2.57 Mbps. Considering that I am standing in the center of a shopping center, this is a good result, Tele2 communication penetrates well through the walls of a large shopping center.
At metro Tretyakovskaya. Signal reception - 5.82 Mbps, transmission - 3.22 Mbps.
And at the Krasnogvardeyskaya metro station. Reception - 6.22 Mbps, transmission - 3.77 Mbps. I measured it at the exit from the subway. If you take into account that this is the outskirts of Moscow, it is very decent. I think that the connection is quite acceptable, we can confidently say that it is stable, considering that Tele2 appeared in Moscow just a couple of months ago.
Tele2 has a stable connection in the capital, which is good. I really hope that they will come to the region as soon as possible and I will be able to take full advantage of their connection.
Now you know how cellular communication works!
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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 manually switched. In the Soviet Union, radiotelephone communication appeared in 1959 and was called the Altai system. Naturally, it was not publicly available, but was used as a government connection and special services. In 1990-1994, during the collapse of the USSR, from the Soviet research institutes, a large mass of classified developments, including the development of multi-frequency, multi-base radiotelephone communications, were taken out of the cordon “for free”. And in 1991 in the United States, and later in the Russian Federation, a new radiotelephone standard appeared - cellular communication NMT-450 ("Sotel"). 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 (hereinafter 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 microchip of the telephone during the manufacture of the telephone. By activating the SIM-card (Subscriber Identity Module) - a microchip in which the subscriber number is "stitched", the mobile phone receives a mobile identification number (MIN).
The area covered by the GSM (Global System for Mobile communications) network is divided into separate adjacent cells (cells) - hence the name "cellular communications", 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 an even coverage of the area. One medium modern station can simultaneously serve up to 1000 channels. The area of the "honeycomb" in the city is about 0.5-1 km 2, outside the city, depending on the geographical location, it can reach both 20 and 50 km 2. The telephone exchange in each "cell" is controlled by the base station, which receives and transmits signals in a wide range of radio frequencies (dedicated channel - the step for each cell phone is minimal). The base station is connected to a wired telephone network and equipped with equipment for converting a high-frequency signal of a cell phone into a low-frequency signal of a wired telephone and vice versa, which ensures the pairing of these two systems. Technically, the modern equipment of the base station occupies an area of 1 ... 3 m 2 and is located within one small room, where its operation is carried out in automatic mode. For the stable operation of such a station, only a wired connection with a telephone exchange (ATS) and a 220 V mains supply are required.
In cities and towns with a large congestion of houses, base station transmitters are located directly on the roofs of houses. In the suburbs and in open areas, towers are used in several sections (they can often be seen located along the highway).
The coverage area of neighboring stations is contiguous. When a telephone moves between the 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 received 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, the account number of its owner and the binding of the device to a specific zone in which it is at a given time is carried out. This moment is very important - already at this stage it is possible to control the movement of this or that object, and who benefits from it, the question is different - the main thing is there is an opportunity ...
When a user connects with someone on his phone, the base station assigns him one of the free frequencies of the zone in which he is located, makes the appropriate changes to his account (deducts funds) and transfers his call to the destination.
If a mobile user during a conversation moves from one communication zone to another, the base station of the abandoned zone (cell) automatically transfers the communication signal to the free frequency of the adjacent zone (cell).
The analog principle of information transmission is based on the emission of a non-digital radio signal into the air, therefore, having tuned in to the corresponding frequency of such a communication channel, it is theoretically possible to listen to the conversation. However, it is worth "cooling especially hot heads" - it is not so easy to listen to cellular communications of this standard, since they are encrypted (distorted) and an appropriate decoder is needed for accurate speech recognition. Negotiation of this standard is easier to find direction than, say, the GSM-digital cellular communication standard, whose mobile phones transmit and receive information in the form of a digital code. Stationary or stationary objects performing cellular communication are easiest to find, while mobile ones are more difficult, since the movement of a subscriber during a conversation is accompanied by a decrease in signal power 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 an intersection of the location of the radio signal source. The peculiarity of this method is that it can be applied at someone's order, for example, bodies authorized by law.
The second method is through a cellular operator, which automatically constantly registers where this or that subscriber is at a given time, even if he does not conduct any conversations. This registration takes place automatically by identifying service signals automatically transmitted by the cell phone to the base station (this was discussed earlier). The accuracy of determining the location of the subscriber depends on a number of factors: topography of the area, the presence of interference and signal reflection from buildings, the position of base stations and their congestion (the number of active mobile phones of the operator in a given cell), the size of the cell. Hence, the accuracy of determining the location of a cellular subscriber in a city is noticeably higher than in an open area, 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, the time of the call, etc.) allows you to restore the picture of all the subscriber's movements in the past. The data is automatically registered with the mobile operator (for billing and not only ...), since the payment for such services is based on the duration of the 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 - confidentiality is provided, but not for everyone. If it is necessary to eavesdrop on your conversations, or determine your location, almost any "equipped" special service, or criminal community, can do this without any effort.
It is more difficult to intercept a conversation if it is being conducted from a moving vehicle. the distance between the cell phone user and the direction finding equipment (when it comes to analog communication) 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 of the operating frequency - this makes it difficult to intercept the entire conversation as a whole (if it is not conducted purposefully with the participation of the telecom operator), since it takes time to find a new frequency.
You can draw conclusions from this yourself. Switch off your cell phone if you do not want your location to be known.
Hidden features of cell phones
A modern MTA can be switched on to the dictaphone mode (recording sounds from the built-in microphone) automatically by a signal, or by a given program, without the authorization of its owner. It is not a fact that every MTA records the speech and voice of the owner, and then transmits the information, but such a possibility is technically provided in every modern MTA. This is akin to a gun that hangs on the wall. And if the action takes place during a performance in a theater, it is almost obvious that the gun will go off before the end of the performance. So in this case, the MTA has the ability to record and transfer 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 - cell. How is the transmission of information on the air? The MTA communicates with the station in bursts of digital pulse signals called time slots. The duration of one service communication session can last from fractions of a second to several seconds.
The MTA maintains such intercom sessions with the base station all the time when the cell phone is in the on state. Initially, this happens after turning on the power of the MTA, 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 a cell phone in the network, etc.) , that is, it is registered on the network. Based on this registration, during subsequent negotiations, this subscriber is charged for connections, communication services, tariffication of calls and roaming. In addition to the time slots in the communication session when the power is turned on, the MTA periodically, approximately once an hour (and with 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 is (frequency) from 10 to 35 times a day. In this case, the duration of time slots fluctuates in the range of 2-25 milliseconds.
In many modern MTAs, the functions of various types of service informing the owner are automatically enabled, 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 what kind of signals your "mobile phone" sends to the base station without special equipment. You can only fix the very fact of a short communication session that occurred without the participation of the owner of the MTA. In any case, if you received an SMS message, then there was an exchange of time slots.
Every owner of a cell phone should know this feature of “his” MTA, despite the fact that the manufacturing companies are not in a hurry to share this information with the buyers of their goods, or to explain these functions and their purpose. As the saying goes, forewarned is protected ... An indirect sign of the MTA's operation for 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), mobile telephones (MTA), purchased abroad and requiring Russification, prevailed among the population. In addition, some of the cell phones brought from abroad to the CIS (bought on the secondary market, because it is cheap), when the local operator's SIM card was connected, turned out to be blocked (they did not implement some of the functions declared in the MTA menu and in its operating manual) ... People carried the MTA to the appropriate service (according to the name of the MTA) and sometimes received an answer: your phone will not work in Russia. Since then, MTAs, brought from abroad by private order, began to be secretly divided into "white" and "gray". The "whites" can be reanimated and used in the CIS "to the full extent", while the "gray" ones are practically hopeless, or require such investments that outweigh its very cost. Therefore, for some time now, "gray" mobile devices enter Russia only in single copies, or in batches imported by small "shuttle traders", or after Russians have a rest abroad, due to their ignorance. In this regard, a test method for testing MTA was born.
For the test, you must sequentially press the keys on the keyboard: * # 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 case under the battery. How will they help?
The specified data is the IMEI (International Mobile Equipment Identifier) of your MTA. After this procedure of notification to the cellular company, your MTA, together with the SIM-card (or even a newly inserted one), will be under the control of your cellular operator. It is better to find out this number in advance (when buying or using an 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 in order for your MTA to be found exactly, or at least to be blocked from service by the operator you were using before you lost your phone.
Today it is difficult to imagine a modern person without a mobile phone, although only 25 years ago only the wealthiest citizens could afford to buy this device in Russia. According to TMT Consulting, at the end of 2015 there were 251.8 million mobile subscribers in Russia, which is 105.3 million more than the entire population of the country - one and a half mobile phones per person. Phones have long ceased to be a luxury item. It is all the more interesting to look into the recent past, when mobile phones in Russia were considered exotic, and only a select few could talk with relatives and friends from different parts of the country.
A bit of history
The development of the first cell phone began in 1947 by the American company Bell Labs. The idea of such a device instantly captured the minds of leading engineers in the United States and Russia. Another American company interested in mobile phones is Motorola. In Russia, in 1957, engineer Leonid Ivanovich Kupriyanovich demonstrated the portable telephone LK-1. It weighed 3 kg, worked no more than 30 hours, but provided a range of up to 30 km. In 1958, he was presented with a device weighing 500 g, and already in 1961, a phone with a weight of only 70 g was allegedly appeared. Only a photograph of this device of dubious quality has survived to this day, the development of which was either discontinued or transferred to the special services (supporters of the theories conspiracy dedicated).
Instead of this revolutionary device, the Russians saw the Altai apparatus, which could only be transported in a car, which was what the ambulance staff used. The developments of Kupriyanovich formed the basis for several Bulgarian devices of 1966, the PAT-05, ATRT-05 and the RATTs-10 base station, which were used at industrial facilities. In 1973, Motorola put an end to the struggle for supremacy: Martin Cooper called Bell Labs from a phone that fits comfortably in his hand and does not require additional accessories. measuring 22.5x12.5x3.75 cm weighed 1.15 kg, consisted of 2000 parts, and the battery charge was enough for only 20 minutes of conversation. It took another 10 years to finalize the mobile phone, and only on March 6, 1983, the phone, weighing 800 grams, went on sale for $ 3500.
In Russia, the topic of commercial mobile communications was not raised until 1986. The Minister of Communications of the USSR Gennady Kudryavtsev said that the KGB and the security forces considered the available cellular communication a threat to national security. An epochal event was Mikhail Gorbachev's call from Helsinki to Moscow in 1987 on the first telephone for NMT networks. Five years were left before the release of the first GSM-phone - it was, and this changed the cellular communication forever.
Russian realities
The first call from Russia to the USA took place on September 9, 1991 within the walls of Delta-Telecom using a Nokia Mobira MD 59 NB2 device using the NMT-450 communication standard. It was carried out by the mayor of the city of St. Petersburg Anatoly Sobchak. The phone weighed about 3 kg, cost $ 4000 (and $ 1995 under the operator's contract), and a minute of conversation cost $ 1. Despite the high cost and size of the device, Delta managed to make mobile 10,000 subscribers in the first 4 years of operation.
Cellular communications reached Moscow only in 1992 by the efforts of Ericsson and Moscow Cellular Communications. Within a year, cellular communication became available to 5,000 Muscovites. In the same 1992, a new player, VimpelCom, with the Beeline trademark, appeared on the Russian market. On July 12, 1992, the first call from Motorola DynaTAC, popularly called "brick", rang in the company's office.
At this time, the GSM network was launched in Germany, which quickly became the world standard. In Russia, the first operator to adopt GSM was MTS, which began commercial operation of the network in 1994. In the same year, the first call came from the office of the North-West GSM operator (now MegaFon), but it only started commercial activity in 1995.
According to Jan Varebi from Ericsson, the introduction of GSM networks allowed Russia to start developing cellular communications faster than many other countries, ahead of the founders of the standard.
Mobility price
Not everyone could become the owner of a mobile phone. The average price of the device was $ 2,500, and the subscriber had to pay almost $ 2,500 as a down payment and connection fee. "Only" for $ 5000 it was possible to become mobile and modern. But this was far from the end of waste. Expensive subscription fees and the price of a minute of conversation forced subscribers to pay at least $ 200 monthly at the end of 1998. Now communication services with unlimited Internet access and messaging cost no more than $ 10. Nevertheless, by the end of the 90s, about 20 million SIM cards were sold in the country, but a real boom happened in the early 2000s. There were about 30 million subscribers in the country already in 2003, and by 2010 their number had grown to 216 million. The release of more and more affordable mobile phones contributed to the cheapening of cellular communications, many of which became cult:, and many others.
Next generation communication
In 2003, Delta-Telecom launched a 3G / CDMA200 network under the Sky-Link brand, but a commercial network based on the EV-DO standard was ready only by 2005. In 2007, MegaFon built the first 3G / UMTS-based network, and in 2008 all the Big Three operators began developing 3G in the regions. The appearance of mobile phones of the type with large touch screens and support for high-speed connections required an increase in the speed and capacity of networks for transmitting not only voice, but also photo or video images, multimedia messages. In 2008, under the Yota brand, Scartel launched the first commercial WiMAX network in Russia, and became the first device in the world to support this network simultaneously with GSM. The rapid development of 4G LTE networks in Russia began at the end of 2011, and MegaFon became the first operator to provide new generation communications for subscribers.
From this moment the modern mobile history of Russia begins. Over the past 5 years, subscribers have begun to actively use the mobile Internet, preferring to communicate via the Internet to regular calls. All modern smartphones have quick access to the network, and the most affordable phones with 4G support can be found at a price of 3,500 rubles in operators' salons. The mobile phone has become as familiar and commonplace as the electric kettle. Reducing the cost of production and the emergence of new players on the market make mobile communications more accessible even for the most remote and poorest corners of the world. 25 years ago it was impossible to imagine the scale of the spread of cellular communications in Russia, but what awaits us in another 25 years?
