The principle of operation of cellular communication presentation. Presentation on the topic "cellular communications"

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Popov Alexander Stepanovich

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In July 1947, Bell Laboratories employees W. Shockley, J. Bardeen and W. Brattain invented

transistor.

D. Ring's idea - Base stations form cells with their coverage areas, the size of which is determined by the territorial density of network subscribers. Frequency channels used for the operation of one of the base stations of the network can be used by other base stations of this network.

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Martin Cooper

Taking the Motorola Dina-TAC in his hands, Martin Cooper went outside and made the world's first phone call. cell phone.

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Cellular communication of the first generation (1G).

Standard CDMA, TDMA, iDEN, PDS, PHS

Data in such networks could be transmitted only at low speeds up to 2.4 kbps, and the spectrum is limited from above by a frequency of 900 MHz.

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Cellular communication of the second generation (2G).

GSM standard

The main difference between the second generation systems is that they are "digital", i.e. voice is transmitted digitally.

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Cellular communication of the third generation (3G).

The systems operate at the following data rates: for subscribers with high mobility (up to 120 km/h) - at least 144 kbit/s, for subscribers with low mobility (up to 3 km/h) - 384 kbit/s, for fixed objects at short distances - 2.048 Mbps.

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base stations.

Base station (in relation to cellular communication) - a complex of radio transmitting equipment (repeaters, transceivers) that communicates with the end subscriber device - a cellular phone.

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The phone can communicate with the station using an analog protocol (AMPS, NAMPS, NMT-450) or digital (DAMPS, CDMA, GSM, UMTS).

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1. Button of the graphical manipulator2. Call button 3. Phone book 4. Keyboard5. Antenna6. Sound speaker 7. LCD display8. Key on-off and call rejection9. Cancel key10. Microphone (located on the bottom)

Appearance mobile phone

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Block diagram of a cell phone

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Cellular encoding and decoding processes GSM communications phone

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Cell phone operation

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A cell phone is different in that it inflicts a "triple blow" on our body. Here we mean three radiation sources of microwave fields located in the same device and generating different EMFs in different modes of its operation.

1. The first of these is a cell phone antenna, which emits EMF, the power of which is determined in units of watts.

2. This radiation is carried out in the transmission mode, and a significant part of the EMR, partially attenuated by the cranium, penetrates into our brain. In standby mode, a cell phone is like other electronic devices and emits weak fields of non-thermal intensity, which, if accumulated in the body, can lead to negative consequences.

3. In the receiving mode, microwave radiation through the ear canal penetrates directly into the brain.

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As a result of numerous studies in the field of biological action electromagnetic radiation, it was found:

1. that they have the ability to accumulate over time in the human body, while violating its bioenergetic balance and, first of all, the structure of the so-called. energy-information exchange (ENIO), which ensures the normal functioning of information-exchange processes between all organs and systems, at all levels of the organization human body, including also those between the organism and the external environment.

2. The most sensitive systems of the human body are: nervous, immune, endocrine and reproductive (sexual).

3. The biological effect of EMF under conditions of long-term exposure can lead to the development of long-term consequences, including degenerative processes of the central nervous system, blood cancer (leukemia), brain tumors, hormonal diseases, etc.

4. EMFs are especially dangerous for children and pregnant women, since the child's body, which has not yet formed, is highly sensitive to the effects of such fields.

5. People with diseases of the central nervous, hormonal, cardiovascular system, allergy sufferers and people with weakened immune systems are also very sensitive to the action of EMF.

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Cell phone interferes with healthy sleep.

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Children slow down...

Alan Preece, head of the biophysics department at the Bristol Cancer Center, gave phones to kids aged 10 to 11 for half an hour. For half, they worked in talk mode, for others they were turned off. And then the scientist conducted neurophysiological tests. For those who got the included mobile phones, all reactions turned out to be slow. Another experiment showed that even after a two-minute conversation in adolescents aged 11-13, the bioelectrical activity of the brain changes. It returns to normal only after two hours. What does it mean? The child’s mood changes, he perceives the material worse in the lesson if he chatted on his cell phone during the break.

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And adults bleed

Hungarian biologist Turocsy asked 76 volunteers to make two calls, 7.5 minutes each. The body trembled with all the fibers: the biocurrents of the brain changed, cerebral circulation slowed down, blood pressure dropped. Doctors recorded anxiety and stress in the subjects.

And Russian professor Igor Belyaev, who works at Stockholm University, turned on the phone next to test tubes with human blood. An hour later, the blood in several of them “boiled”! “No, it didn't get hot,” the researcher explains. “But the blood cells, the lymphocytes, behaved as if a person had a very high fever - 44 degrees.” The effect of "heat shock" persisted for 72 hours.

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Embryos die...

At the Moscow Institute of Biophysics, Professor Yuri Grigoriev made two incubators. I put 63 chicken eggs in each. Above one "bird house" at a height of 10 cm, a GSM mobile phone was hung. The phone worked in this mode: 1.5 minutes on, half a minute off. Violations of embryonic development began on the third day. Only 16 birds hatched, which "listened" to the phone! But they were also not viable. For comparison: in an incubator where eggs were not pestered by calls, 51 chicks were born without any problems.

scientists from Moscow State University found that yeast fungi and acetic acid bacteria wither from a mobile phone. And this means that the apparatus on a belt or in a pocket - next to the intestines - can ruin the life of one of the 500 microorganisms living there! And they will take revenge on the careless owner.

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SAR - Specific Absorbtion Rate - a unit of measurement showing the maximum specific power absorbed by the human body (W / kg) during a normal conversation on a cell phone.

The maximum safe level is 2.0, most modern phones have an SAR between 0.5 and 1.0.

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• At what age did you start using a cell phone?
• How much time per day do you talk on your cell phone?
• What phone model do you have now?
• Where do you usually keep your cell phone?
• Where is your cell phone at night?
• Do you know the device of a cell phone?
• Do you know about the harmful effects of cell phones on the human body?

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At what age did you get a cell phone?

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2. How much time per day do you talk on your cell phone?

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3. What phone model do you have now?

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SAR RESULTS ARE THE SAFEEST

You are given the opportunity to get acquainted with the list of mobile phones with the lowest level of SAR radiation. All data are given for phones operating in GSM standard 900. The table shows the SAR values ​​determined for 10 g of tissue. Remember: the lower the SAR value, the less impact a mobile phone has on a person! Learn more about SAR

• SAR Model
• MagComMagCom 0.04
• Motorola StarTac 130 0.07
• Samsung SGH-F700v Qbowl 0.07
• Motorola V100 0.09
• Samsung SGH-Z560 0.10
• Swisscom XPA v1615 0.10
• Motorola MPx200 0.12
• Philips 362 0.12
• TelefoonTotaalBasicPhone 0.12
• Mitac Mio A501 0.12
• Samsung SGH-X830 0.12
• LG S5200 0.12
• Audiovox XV6600 0.12
• LG KG320S 0.13
• Sagem myMobileTV2 0.13
• Motorola V101 0.14
• Sony Ericsson T292a 0.15
• Nokia 8810 0.15
• E-ten M500 0.16
• Vodafone VPA IV 0.17
• Blackberry 7280 0.17
• Samsung GT-I8000 Omnia II 0.17
• T-Mobile MDA Pro 0.17
• Blackberry 6280 0.18
• Samsung SGH-s105 0.18

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Conclusion: the influence of electromagnetic fields on human health is the research problem of science. A person can ensure his own safety if he has the necessary information. Each of us can and even must take simple precautions. A cell phone is only safe if you treat it reasonably.

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List of used sources and literature

A.Gridin, K.Romanov, I.Zubik “MOBILE PHONE FOR EVERYONE. Device and operation of mobile phones»

Malyarevsky A., Olevskaya N. Your mobile phone (a 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. Fundamentals of cellular communications of the GSM standard ("Engineering Encyclopedia of the Fuel and Energy Complex"). M., Eco-Trends, 2005

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Cell phone device

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Principles of cellular communication use of light, signals and sound) The beginning of the history of wireless communications

• Many times in history, heliographs, flags (semaphore), ...
- China, Han Dynasty (206 BC - 24 AD) use of signal towers; - 150g. BC. smoke signals for communication (Polybius, Greece) - 1793, optical telegraph, French engineer K. Chapp

• The beginning of communication with electromagnetic waves:

James Maxwell (1831-79): theory of electromagnetic fields, wave equations (1864)

1876 ​​Alexander Bell telephone

G. Hertz (1857-94) demonstrated the wave type of electrical transmission through space (1888)

On May 7, 1895, the St. Petersburg physicist Alexander Popov made a report at the Physico-Chemical Society with a demonstration of a radio device he had created for recording atmospheric vibrations.

On June 2, 1896, Guglielmo MARCONI patented the radio as his invention (Popov's scientific publications on this subject appeared in the same month, but were addressed to a completely different audience).

In 1896, in London, he managed to transmit a message over a distance of 10 kilometers.

1907 Commercial transatlantic communications - huge base stations (with antenna heights of 30 - 100m)

1915 speech transmission New York - San Francisco

In 1896, he demonstrated his experiments in front of the Physical Society of St. Petersburg, transmitting signals using Morse code inside the university building.

The beginning of the history of wireless communications Concepts:

• large area for one transmitter
• Great “mobility” due to high energy intensity
• Low capability systems prone to interference
• High price

1911 - airship mobile transmitter

1926 - train (Hamburg Berlin)

1927 - First commercial car radio (receive only)

First mobile systems connections began in the 40s in the USA and in the 50s in Europe.

Development of telecommunications in Russia

Development of telecommunications in Russia Classification of wireless networks

Common use

departmental

control rooms

Trunking

paging

satellite

computer

optical

Development of standards for cellular communication systems Development of standards for cellular communication systems Cellular communication networks

• 1G: analog networks. Idea: covering space with "cells" (zones of coverage of one base station) and organizing clusters of cells. Supported only telephony. Standards: NMT, AMPS.
• 2G: digital networks with circuit switching. A time division access method is used. It also has a honeycomb structure. Support telephony and data transmission. To organize more quick access GPRS (2G+) can be used. Standards: GSM, D-AMPS, PDC.
• 3G: circuit/packet switched digital networks. Wideband code division access method is used, support the transmission of multi-service traffic. Standards: CDMA, WCDMA, cdma2000, i-mode, etc.
• 4G: packet-switched digital networks. Are under development 

Cellular 3G networks

746-794MHz, 1.7-1.85GHz, 2.5-2.7GHz

Cellular GSM

• 800-900 MHz

Cellular GSM

• 1.85-1.99GHz

Wireless LANs (IEEE 802.11b/g)

• 2.4GHz

Bluetooth

• 2.45GHz

Wireless LANs (IEEE 802.11a)

• 5GHz

Geometric structure of a cellular system Frequency reuse model

Cell types

Macrocells(3 to 35 km)

Microcells(0.1 to 1 km)

Picocells(0.01 to 1km)

Nanocells(1m to 10m)

General view of the cellular system

Network sub-system

Example of mobile cellular connection Example of mobile cellular connection Example of mobile cellular connection Example of mobile cellular connection Example of mobile cellular connection Example of mobile cellular connection Example of mobile cellular connection

During the century and a half that have passed since the invention of the telephone, telephone communication has become so firmly established in the life of a modern person that the absence of a telephone in an apartment has practically become an exception. To the advantages of wired telephone networks should include the reliability of communication and a developed system of subscriber networks, which allows the user to contact a subscriber in almost any country in the world.

However, the "hard binding" of the subscriber to the stationary telephone set, "limited" to the same length of the handset wire, did not allow the user to be mobile, i.e. move freely in space during or between conversations.

In the second half of the last century, as technology and technology improved, the idea of ​​​​creating a worldwide (global) network began to develop. mobile (cellular) telephony, which allows the user to have access to a developed subscriber network using a portable portable (mobile) handset-telephone with a significant (tens of kilometers) range.

The implementation of this idea would bring telephone communications to a new level of popularity and accessibility from the point of view of the user, who would have his own individual phone number and virtually unlimited freedom of movement (mobility) during or between calls.

The proposed principle of operation of mobile telephony is quite simple: using a handset-telephone (mobile phone), the subscriber contacts the nearest base station (transmitter) of the network (Fig. 224).

Rice. 224. Cellular network base station (transmitter)

This base station, in turn, communicates with the next network transmitter, and so on, as the subscriber requires (Fig. 225).

Rice. 225. Cellular transmitter network

The described principle of creating a developed subscriber network is called cellular principle, since by the same principle bees build honeycombs inside the hive. In this case, each created cell serves as the basis for creating the next exactly the same cell, etc.

Due to this circumstance, mobile telephony is also called cellular telephone connection. When a subscriber moves (for example, by car) (see Fig. 225), the base stations independently monitor him and “transmit” to each other, which happens with virtually no loss of communication quality, quickly and completely unnoticed by the user.

The easiest part block diagram cellular communication - a mobile (portable) telephone, consists of two parts: the “handset” itself or ME (Mobile Equipment) and the subscriber identification module, or smart cards SIM (Subscriber Identity Module), obtained by concluding a contract with a particular operator.

Each cell phone is assigned its own number or international identifier during production. mobile deviceΙΜΕΙ (International Mobile Equipment Identity), which allows you to distinguish it from the second exactly the same.

Our country uses the second generation network standard GSM (Global System for Mobile Communications), which was developed in 1990. This standard uses an operating frequency of ν = 900 MHz, which can significantly improve the quality of communication compared to the first generation standards.

The first GSM operator accepted subscribers in 1991, and by the beginning of 1994, global networks based on this standard, had 1.3 million subscribers. By the end of 1995 their number had increased to 10 million!

When you turn on a mobile phone with an activated smart card, it “by itself” finds the nearest base station corresponding cellular network, after which the entire package telephone services this network becomes available to the subscriber.

Each transmitter provides radio coverage on average at a distance of up to two tens of kilometers from it (Fig. 226). For the rational use of the cellular network of transmitters, optimal schemes for their relative position on the ground are developed, taking into account its relief.