Extended Cell GSM How Works. How the GSM networks or brief bonds are working. Cable and antenna adapters

One buddy asks another:
- And why is the one who speaks through a cellular man,
Is constantly scattered and gets up again?
- He catches the wave or snipers is afraid.
Anecdote on the Evil of the Day (C)

Introduction

Everyone wants his cell phone really mobile. It's nice if your device adopts a signal in any place and you can talk without digital chilli and interrupts. In the end, mobile communications should give such freedom. Most of the civilized countries have 100% coverage. This means that at any point of the country you can accept and make challenges. This is a kind of suspension of communication. For Russia, such an opportunity is not visible yet even on the horizon. We have so many land, and there are so few people that each bush is covered is economically inexpedient. So you have to think operators where and how to put another base station. Of course, the likelihood that the equipment will appear in the taiga, significantly less than near a large automotive or railway road. As a result, the sensitivity and power of its receiving and transmitting contours becomes not the last argument when buying a cell phone. I recall the help of cellular development, when high-quality tubes really gave mobility to their users, and the owners of simplified solutions experienced problems. Now the major cities are covered very well, but still the moments come to memory when your interlocutor requests you to approach the window or find a place where the connection is better. It pleases one thing - every year the number of base stations is continuously growing and the coverage area increases. This process is irreversible. Some time ago I visited the remote area of \u200b\u200bthe Tver region. There we encountered the situation when "tricky" cell phones refused to work. The network appeared, it disappeared. Among us was the happy owner of the raritet Siemens S35. He spoke from any place. This explicitly testified in favor of the fact that all the tubes are different and used to be able to do real combat mobilies. All tubes use different hardware database and, accordingly, the quality of communication in extreme conditions (by low signal level) provide different. Time has passed, and the case from memory does not allow sleeping calmly. I gave myself a chain of the next cell unit to buy only on condition that it will guarantee me a quality technique. Time passed, and the new mobile phone was never purchased. Today's material should bring us closer to understanding the problem of the "sensitivity" of a cell phone. His reading does not guarantee you uninterrupted communication, but decompose on the shelves all the technical aspects that are directly related to the receiver and the transmitter of your tube. Also you will learn how not to get on the hook of crooks.

A bit of theory

So, to go to the subject conversation on today's topic, you need to deal with constants. To begin with, all below is applicable applicable to GSM communication. Since most Russian users choose this particular standard, then we take responsibility to write for them. However, with a proper mind and an incomplete mixture, you can conduct analogies for all other types of mobile communications. Somewhere expressed by us will work almost without metamorphosis, and sometimes you have to get away from the troped trail of a well-known solution. In the end, legs grow from one place. In this case, from a mobile phone. Now you can safely move to basic theoretical calculations. Any mobile phone has a transmitter and receiver. Therefore, conversations in a pure form about the sensitivity of the cell phone in a sense are not correct. You need to separate the power of the transmitter, the realization of the antenna and the sensitivity of the receiver. Of course, different manufacturers use not completely identical parts or hardware database. Therefore, the tubes work in different ways. In addition, some design features of the mobile phone - the geometry of the antenna and the case, your position in space and external factors affect the quality of communication. However, in this chaos there are several basic settings for which we can rely on. Of course, these are standards for cellular communication. They are spelled out and signed many years ago. Each developer undertakes to perform and holy to honor them, as well as the country's president promises not to violate the Constitution. In this and different case, some violations are possible, but no one gets pleasure from violation. Sanctions are possible. The presidents in this case turn out to be protected much better. For example, it will solve the tricky Asian or European company to create a mobile phone with a super powerful antenna. It would seem that buyers will find, and advertising slogans - "Our antennas are broadcasting so that you are heard in the near constellation" may abandon the psyche of competitors. But here to sell such tubes will not work. All sorts of standards committees wrapped the whole business. Such is the situation.

Cell phone creature almost alive. He is always trying to chat with the base station. This happens, regardless of the desire of the owner. Of course, if the tube is in the on state. The base station transmits a signal for the tube at 935.2 - 959.8 MHz (important! It is about GSM900), and the mobile phone broadcasts at frequencies of 890.2 - 914.8 MHz. Sigor mathematical calculations suggest that the maximum possible distance between the cell phone and the base station can be 35 km. This is due to the work of the TDMA technology - each mobile station is highlighted by a time slot in 0.577 milliseconds (more precisely, the ratio of 15/26 is running), during which time the mobile station should have time to answer honeycomb. The speed of propagation of radio waves is a finite and well known - 300 thousand km / s, the maximum distance is calculated as a simple multiplication of time to speed. This is how these are the most 35 km. However, if the theoretical calculated value looks very beautiful, then in reality everything is somewhat different. For GSM-900, there are 5 cell power classes: 1st - 20 W, 2nd - 8 W, 3rd - 5 W, 4th - 2 W and 5th - 0.8 W. Really, we did not meet any wearable tube with a capacity of more than 2 W. It is impossible to break the distance of 35 km with such characteristics. If you increase the power of the base station, it is sufficient to simply - you need to install a transformer more powerful and negotiate with the supervision authorities, then give each user a generator or an acidic fifty-cellogram battery behind the back is not possible. A literally all: the weather, relief, infrastructure and much more plays against the subscriber of the cellular network. So the real distance at which the connection is possible in each particular case is achieved by a simple experiment with a cell phone. In other words, you are given the most real reason to reliably measure the "sensitivity" of your cellular apparatus in the field. Remember that the magnitude you measured will be firmly firmly tied to a specific cell phone and changeable weather conditions. Take a couple of tubes for a test in the mobile phone store you will most likely not allow. Therefore, it makes sense only one action - be observed. Suppose you ended up in the zone of not quite confident reception. Assess the comrades how things are with their cellular negotiations. Such experience is not the highest guarantee of success when buying. We have previously written that even in one delivery of one brand tube can work differently. Even soldering a robot cannot guarantee an absolutely identical connection of conductors, which is to talk about semiconductors and uniformity of antennas.

I see, but I do not hear at all!

Probably you sometimes observed such a picture on your cell phone that your network logo is present on the screen, and the challenges are practically not possible. The situation is your satellite under an insufficient signal. Some inertness of the logo is able to kill all human in the subscribers. Sometimes the picture aggravates the fact that your mobile phone fell out of the network, and a friend's tube continues to draw a picture that says that there is a connection on his tube. Let's figure it out with this interesting fact. It turns out, not everything is so difficult and simply explained. So, let's turn again to the work of the cellular network. It is known that for automatic control and power on the tube, information about the levels of signals of base stations is required. Each phone with a given time interval measures the signal level from the base station. This is done regardless of whether you say on the tube or it is in the call standby mode. What is it done for? Often the tube "sees" several basic stations (BS) at once. The network organization is built in such a way that at one point in time it can communicate (your conversations are passing) only through one BS. The mobile phone measures the signal level from different base stations and selects the one that "seems much more clear." This is logical and is a basic network of network. The cell phone measures the input level at the frequencies specified by the system. Not necessarily the nearest cell will become yours. Sometimes you are connected to a territorially longer station, the main one with a higher signal. Is it possible to switch the device to another basic station? In ordinary mode of cell phone, it is not possible. If you change the firmware and enable the user with access to hardware settings, then it is possible.

Go ahead. The tube measures the power of the input signal. Of course, it is impossible to do it without error. GSM standards provide a permissible measurement error when working under normal conditions by 6.3 times (+/- 4 dB). For "hard" working conditions, whether, for example, a very low temperature, the standard permits the error of 15.8 times (+/- 6 dB). All these errors really work for fully serviceable tubes. It would be very difficult to live without them, as Mobile manufacturers are physically not able to provide the reference measurement of incoming power. After we learned about the error of power measurement, it remains to go to a specific example. Suppose you have been in place with your handset, where the real level of the base station signal is -103 dB. Settings for shared networks are delivered in such a way that they are reported to the tube that access to it is allowed at the level of the measured signal -105 dB. Of course, here all our errors get out. The mobile phone receiver is made so that the signal level is lowered by 4 dB. The measured tube signal will be -107 dB. So, fully working and responding to all standards tube will be reset from the network, as it does not have the right to be included in the system. Another cell phone has such an implementation that it will overestimate the measured signal of 4 dB. He will be able to register on the network and will show her logo on the screen. Let's just say that if the actual signal level for such a tube will be -108 dB (at the place where it is), then the device will still be registered in the operator's network. Here you have a "sensitivity" of cellular devices. So the presence of a logo on the screen of your phone is talking about the registration of the tube on the network, but does not guarantee a normal connection. However, it is still nice. An attempt to talk can sometimes be counted for the call itself. So, dear readers, I wish you have a tube with such a receiver and a measuring path, which will constantly overestimate the signal power level from the base station. Thus, we completely destroyed the myth that users of different cell phones can be measured by signal levels, which is displayed on their mobile phone screens. Indeed, such conversations are carried out only from deep illiteracy in the matter. In the future, when you have to ask about the signal level and appeal to information on the screen of the tube, it is not worth spending time on empty conversations. It makes no sense to compare the measured power of the incoming signal, and about the "reference cubes" it is worth forgetting. How this phone manufacturer recalculates data in them remains a mystery. It does not make sense to spend your time on its disclosure.

Dance with cellotov

Any duplex radio station, and a cell phone is a special case of this rule, uses an antenna for receiving and transmitting the signal. This fact is another argument of ephemerality of the concept of "sensitivity." Separate use of the same element of the tube entails some compromise. The transmitter should not be found on the receiver, and the latter in turn must not interfere with the first. We all live on the planet Earth and fully respond to the physical rules that the nature imposes on us. Therefore, it is stupid to believe that one electrical device can not interfere with the other. As a result, developers come to an elementary compromise. It is he who allows the device to function so that you, subscribers, you can hear the voice of your interlocutor in the tube. By the way, his majesty compromise is often made in favor of the receiver. Of course, it would be possible to create not duplex, but simplex gear - at one point in time only one way, but such a connection would not satisfy modern user requests. It makes it possible that if you cover the antenna of a cell phone with your hand, then the conversations will become clear and silent. Let's analyze this situation. Indeed, if you cover the antenna by any object, then in the overwhelming majority of cases, the level of the measured signal of the cell phone will fall. The mobile apparatus is arranged in such a way that the worse he "hears" the cell, the "louder" he answers it. Accordingly, the output power will grow. Its ability to punch your hand or another item that lights up the antenna is not limitless. In addition, the base station will not raise power, as it does not know that the user revenge the interference to its signal and its parameters are simply not designed for it. Accordingly, all your actions are more destructive when you cover your cell phone antenna with hand. By the way, not only the hand, but also metal decorations on it affect the level of the measured incoming signal. When talking on a mobile phone, try to keep your hand as far as possible from the antenna. So health will save and no interference. The reinforced concrete structures becomes excellent interference for cellular communication. Remember, the shorter the wave, the better it permeates them. By the way, this is due to (and not only) the fact that in the city center operators love to use 1800 MHz range. Beyond the city in poor communication conditions, try to rise to all sorts of hillocks. This action removes extra physical interference on the path of electromagnetic waves from the cell phone to the base station. Remember that in the frequency ranges used in cellular communication, even with a small, only a few centimeters, or tens of centimeters, moving antenna, or over time, the signal level may vary 100 and even 1000 times (by 20 - 30 dB) . Be sure to move and look for "successful" places. The moment came to talk to the most dark topic of mobile communications - external and internal antennas. It is difficult to count all the bikes and disputes on this topic. It will only be about regular antennas. Or those already installed in your mobile phones. Of course, additional (remote) antennas with bousers, which you can purchase for individual money, significantly improve the reception and transfer, but I have to forget about mobility. By the way, such solutions are very much like motorists, because they do not have to carry them on themselves. So, internal or external antenna? There is no unambiguous solution to this task. If you know how to solve wave equations and put the boundary conditions, then, having received the true parameters of your mobile phone, you can simulate a call situation in a wide variety of coverage area. A few years ago, one American placed the results of its calculations on the network. They caused long disputes. As a result, he removed them. And a pity, since this is the only example of such calculations. Experience shows that modern built-in antennas are not inferior to external solutions. Life significantly complicate all sorts of home-grown decorations that users broadcast on the antenna. As a result, the antenna can work in non-standard mode and, maybe even harm your health, radiating mainly towards your head.

Extended Cell.

However, the operator can not always put ordinary base stations to cover large areas. Imagine, for example, a desert or water area. Economically, and sometimes it is simply not possible to physically place the desired amount of BS. For GSM standard, a cell configuration is provided, in which the communication range increases to 70 km. It is called Extended Cell. With this use of equipment, the number of conversational channels decreases to 3. But the operator covers the giant area with the forms of only one station.

Not so long ago, near St. Petersburg at the Finnish Bay, one of the operators used Extended Cell. Subscribers could see the name of this operator with an exclamation mark on the screen of their mobile phones. This meant that the tube saw the network, but could not communicate with her. The problem was solved using external directed antennas when the output signal of the device was intensified. Thus, Extended Cell allows you to cover gigantic little territories. However, their use is increasingly popular. In Siberia, such cells will not put anyway, and the resort areas for their cellular load have long surrounded the centers of megalopolis in the intensity of telephone conversations. Extended Cell physically cannot serve such places, and the requirement of an additional antenna does not make this method of communication due to proper popularity.

Attention, Zhuliki

Each user would like to increase the "sensitivity" of a two cellular apparatus. The attackers are ready to use it in their plans to fool the subscribers of mobile networks. It is easiest to fool a person, giving it a service that it is difficult to check. And if its value is small, then it's just a treasure for a rogue. As a result, "Sensitivity amplifiers for mobile phones" appeared on the market. Of course, they are suitable for all types of tubes, implement them via the Internet and they are funny money. The manufacturer of this product declares that the sticker works exclusively according to the laws of physics and gives your phone to unprecedented sensitivity. It seems that stickers conspired by sorcerers and bubble wounded, they would also be sold quite well enough, but the fraudsters decided to play on the veins of the crowd and mass mass of the market. Miraculous stickers to this day with great success are sold on the Internet.

The creators of the stickers recommend pasted it under the battery. Logical move. There, the sticker will not interfere and does not prevent the operation of the real antenna. By the way, the latter for calculations are tremendous. Each antenna is unique in its own way and the common panacea for all this manifold can not be. Fraudsters can only upset your regular antenna. Perhaps make interference and noise. Doubtfully advertising statement that one sticker replaces the antenna long per meter. The need for such a length can not be. Of course, you can collect a meter antenna, but it will be a very complex and not very necessary system. In a word, fool our brother. By the way, the legs of this stickers grow from Asia. There really sold cell phones and special antennas in the form of stickers to them. However, they refused the system, as users simply could not stick them correctly. It was important to accurately position the sticker in the desired part of the mobile phone. The task was unbearable. So do not waste your money and encourage fraudsters.

Final word

Today we have dealt with the concept of "sensitivity" of a cell phone. The output can be made one. What your handset is qualitatively assembled and the better the element base, the easier you will speak in the zones of weak reception. If you have the opportunity to use remote antennas with a narrow pattern of the orientation, then try them in your work. They really help sometimes solve complex communication situations. We hope that after a while cellular operators will cover the whole globe and we will forget about this problem. Stay in touch!

NetMonitor It is a tool for displaying technical data on the state of the network of the cellular operator. Allows you to determine the level of the incoming signal of the operator and the channel numbers on which this operator works, network type and basic parameters.

In a regular mobile phone, this feature is most often available for a set of a special key combination by type USSD request.

Mainly this information is used for proper selection and installation.

Activating the NetMonitor menu for various phone models:

Apple iPhone 2G, 3G, 3GS, 4G, 4GS, 5 - Firmware version 5.0.1 and above:
* 3001 # 12345 # * then click "Call". We fall into the field Test menu. In the upper left corner, the level of the mobile operator signal reflected in dB is visible. Next, to the GSM Cell Environment / GSM Cell / Neighboring Cells tab, here you can see a list of channels. Total 6 channels. In order to view the channel information should be pressed on the arrow.

Android:
# 0011 # or * # * # 4636 # * # 197328640 # * # *. After pressing the last symbol, the menu appears automatically.

HTC Evo, HTC Incredible, HTC Touch - Verizon
## 33284 # and click the call, then you get into the menu where you need to select the network, the signal level you want to know.

HTC Wizard 8125, 2125
* # * # 364 # * # * Get into the menu. The signal level here is displayed not in DBM, but in conventional units. The greater the value, the higher the signal level, for example, 4 is -105 dBm, and 31 is -50DBM.

HTC Thunderbolt, HTC Inspire 4G
*#*#4636#*#*

HTC Touch.
##33284#

LG LX-350, LX-550 Fusic (Sprint)
##33284#

LG PM-225, PM-325, MM-535, LX5400
## 33284 # or ## 33284 and click OK. If the password asks: 040793 or 000000.

LG C900 Windows 7 Smartphone
First, enter ## 634 # if you ask the password 2277634 # * # and press ENTER.

LG CG300, C1300, L1400, C2000 (GSM Phones)
2945 # * #. In the upper left line, the signal level is shown not in dBm. The higher the value, the more powerful signal.

LG CU400, CU500, TU550 (GSM)
277634 # * #, Select Modem Settings then Engineer Mode and click OK

LG Sprint Touchpoint 1100, 2100, 2200, 5250, 4ne1, 1010, 1200
## 33284 Next Save and OK

LG VX-5300
MENU, then 000000, select Field Test, select Service or Screen. Numerical values \u200b\u200bare signal levels.

Motorola Droid.
Quickly dial * # * # 4636 # * # *, then choose Phone Info.

Motorola V551, V555, V557 (GSM)
073887 * - very quickly it is necessary to dial. Next 000000 Select Test Mode and click OK.

Nokia 2100.
* 3001 # 12345 #, choose Menu Next Follow the instructions.

SAMSUNG A310
Menu, 0, choose Debug

SAMSUNG A460, 3500, A540
MENU, 0, 9, I enter the code 040793, choose Debug Screen

SAMSUNG A500, N400
MENU 010, I enter 040793, choose Debug Screen

SAMSUNG A620, A660, A860, M300
## 33284 and click OK, then dial 040793, select Debug Screen and click OK.

SAMSUNG A630, A650, N330
Press Menu, 9, *. Enter the code 000000, select Debug Screen, click OK.

SAMSUNG A670, A570
Press Menu, 7, *. Enter the code 000000, select Debug Screen

SAMSUNG A560, A740, A760, A840, A880, P207
## 33284 #, click OK, enter the code 040793, select Debug Screen and click OK.

SAMSUNG A790.
## 33284 #, enter code 040793, signal level after D.

SAMSUNG A740, A850, A930, U740, A870 (Verizon)
Menu (Central Blue Button), select Settings & Tools and click #. Next, enter 000000, select Debug Screen. For example, T-63 D089 means that the level of signal -89 DBM.

SAMSUNG A900, A920, A570
## 33284 # or ## 33284 and click blue ok. In the Enter code 040793 or 000000 field. Select Debug Screen or Field Test and then Screen. The signal level will be after the letter D.

Samsung e105, D807, A517, E316, E317, x426, x427, x475, S300, S307, D347
Enter * # 9324 #

Samsung Blackjack SGH-I607, A412, BlackJack II
Enter * # 0011 #

Samsung i730, i760 (Verizon)
** 33284 and code 000000, choose Monitor

Samsung N240.
## 33284 and click OK. Select Debug Screen and click OK.

Samsung u520, u340
Press MENU (OK button), 9, 0. Next 000000, select Debug Screen. T63 D085-5 means that the signal level is 85 dBm.

Samsung c170, x820
*#9999*0#

ARFCN (Absolute Radio-Frequency Channel Number) is a channel number.

The ARFCN value in the range 1-124 or 974-1024 This means that the operator operator operator in the range of 900 MHz and we need (900 MHz) or the GSM900 repeater.

ARFCN value in the range of 512-886 This means that the operator operator operator is in the range of 1800 MHz and we choose an antenna 1800 or the DCS1800 repeater.

DOWNLINK FREQUENCY - channel number for which the carrier frequency is determined.

If the channel value in the range is 2937-3088, then it is 3G / UMTS900 - and we need the GSM900 antenna or the GSM900 repeater.

If the channel value in the range is 10562-10838, then it is 3G / UMTS2000 - select the 3G antenna for 2100 MHz and the WCDMA2100 repeater.

We advise you to watch information on multiple channels. Also, information on this definition of channel numbers will be more reliable if the data is measured during a connection to another subscriber (incoming or outgoing call). It should be understood that all the values \u200b\u200bof the phone shows only for that cellular operator, the SIM card of which is inserted into the phone at the time of measurements! And if you want to install under two or more cellular operators, then you need to do all the measurements with each sim card!

Nonitorizing programs for smartphones based on Android OS:

To install programs, any smartphone on the basis of Android OS (or almost anyone, Chinese iPhones on Android uses not recommended). The Nexus series devices were well shown (first of all due to the latest version of Android OS), as well as HTC Desire - Nonmonitors on these devices, they show the highest possible information. The devices of other brands and models will also be suitable, but may not display some additional information (for example, a list of neighboring base stations, which is written in more detail below).

If you already have a smartphone, the floor is done. It is necessary to put a netmith program. They are not so much, but there are almost no good and in general. Here are some of them that can be found in Google Play Market:

Network Monitor
Netmon - Radio Network Monitor
NetMonitor
G-MON.
GSM signal monitoring
G-NetTrack
Network Monitor Light

All that is required from the programs is to correctly display the parameters you need to monitor the network and save them to the log-friendly log processing together in some cases with GPS coordinates.

app name	Description
Network Monitor	Does not show neighboring cells, a non-informative interface.
Netmon - Radio Network Monitor	Able to show neighbors and signal levels. Leads quite adequate log. But with the LTE, the program clearly paved - the necessary data does not give out.
NetMonitor	The simplest interface shows the neighboring cells in GSM, displays the signal level, leads the log. The UMTS and LTE behaves adequately, gives all the necessary data.
G-MON.	An informative interface, displays neighbors, issues the desired data in LTE, leads a detailed log.
GSM signal monitoring	Next neighbors, with 3G everything is fine, but in LTE you do not give out.
G-NetTrack	All is well with this program, but in LTE the necessary data does not show.
Network Monitor Light	The application is a certain triumph of the primitivism. It goes to the landfill due to the lack of necessary data in LTE (although even if they were there, it would hardly have been pleasant to use this program).

What to monitor?
To begin with, we will define the task - we need parameters that definitely defining the base station, or rather, the specific sector (cell) of the base station or another minimum positioning cell in the mobile network.

Detailed description of common types of mobile networks and display in NetMonitor:

GSM.

GSM, GLOBAL SYSTEM FOR MOBILE COMMUNICATIONS - Global system for mobile communications. Second generation network. In Ukraine, it is used in the following frequency bands:

GSM-1800.

Also called DCS (Digital Cellular Service, digital cellular service).

The GSM network exists the following parameters:

Parameter	Format	Description
MCC.	3 decimal numbers	Mobile Country Code., Country code. Unique identifier of the country (full list of MCC).
MNC.	2-3 decimal numbers (leading zeros matter, 01 and 001 are different codes)	Mobile Network Code., Mobile network code, Operator code. Unique in the country with MCC (watch the list by countries in Wikipedia or on the website of the International Telecommunication Union (ITU, International Telecommunication Union)).
Plmn ID.	MCC + MNC 1, 5-6 decimal digits	Public Land Mobile Network Identifier, Identifier of the ground mobile network. It is the first 5-6 digits of an IMSI number of the SIM card, in the netmonists, it can be designated simply as a network (NET).
LAC	16-bit integer	Location Area Code., Terrain code. Unique within the network of the operator with the corresponding MNC.
CID	16-bit integer	Cell Identifier, Sot I identifier. Unique within the location with a certain LAC.
TA.	6-bit integer (from 0 to 63)	Timing Advance., Temporary advance, Synchronization advance. The time delay indicator of the signal passing. Increases by 1 with the increase in the remoteness from the base station for every 550 meters.

Thus, we obtain the hierarchical chain of the MCC-MNC-LAC-CID identifiers (PLMN ID-LAC-CID), where all parameters are important for the unambiguous definition of cells in the world. And it is these parameters that any nice-monitor shows us.

If the netmonitator shows the TA parameter, then you can approximately (with a gradation of 550 m) to establish the remoteness of the mobile station from the base station. For positioning, it can be useful if the exact location of the tower is known.

In the GSM network, base stations (BTS, Base Transceiver Station) are transmitted by mobile stations (MS, Mobile Station - Mobile Phone Designation, Modems, etc.) not only information about the cell in which MS works, but also a list of neighboring cells ( NCL, NEIGHBOR CELL LIST). This list is configured for each cell when setting up network parameters and serves to correctly conduct MS transition procedures from one cell to another (such a transition is called handover or handoff, read more).

Non-monitor applications can display a list of neighboring cells, though it works not on all smartphones.

Umts.

UMTS, Universal Mobile Telecommunications System - Universal mobile telecommunication system. Third generation network. In total, the UMTS network has 26 frequency ranges, two of them are used in Ukraine:

room	Name range	Range to transfer, MHz	Range on reception, MHz
1	2100	1920-1980	2110-2170
8	900	880-915	925-960

In UMTS networks, such a concept as a cell (Cell) is not defined. Instead, the concept of service area (Service Area, SA) appears. Each service area may consist of one or more physical cells (cells or sectors, by analogy with GSM), i.e. It can be served by several basic stations (Nodeb) at the same time (this is, by the way, one of the main fundamental differences of third-generation networks from its predecessors). Each cell, in turn, can enter more than one service zone. Those. Service zones can intersect.

Modern devices can simultaneously connect with three physical cells, which helps to ensure the procedure of the so-called. Softer Handover, Soft Handover, without breaking and re-creation of the channel.

Comparison of service zones and cells is transparent, i.e. Unnoticed for data network and, accordingly, for netmithors.

Returning to the parameters that we need to fix in UMTS networks are important for us MCC, MNC, LAC, as well as:

For netmolation, the difference is only in the title - the CID has changed on the SAC, the remaining parameters remained the same, and the unique cell number (in this case, the service zone) has this kind: MCC-MNC-LAC-SAC.

Non-monitor, usually do not make differences in the designation, and the service area code is shown as CID.

As for the list of neighboring cells, it is also present here and is called Neighboring Set. However, neighboring honeycombs here are precisely physical cells, each of which is determined by the non-unique PSC number (Primary Scrambling Code, only 512 of various PSC), so it will not work for positioning.

It is also worth noting that the netmithors, in particular the G-MON, are also recorded by these parameters:

Parameter	Format	Description
RNC ID	16-bit integer	RADIO NETWORK CONTROLLER IDENTFIER, Identifier controller radio network. The radio network controller is needed to control the NodeB base stations group, its number is unique within the operator's network.
C-ID	16-bit integer	Cell Identity., Sot I identifier. It is a unique physical sector identifier for each RNC. Used in composition UC-ID (see below).
UC-ID	RNC ID + C-ID	Utran Cell Identity., Identifier utran1. Unique in the operator's network identifier of the physical cell. Used to identify sectors in NODEB communication interfaces with RNC and RNC with each other.

UTRAN - UNIVERSAL TERRESTRIAL RADIO ACCESS NETWORK, NETWORK OF THE UNIVERSAL INTERNET Radio accessory, the name of the UMTS data network.
It should be noted that the G-MON instead of the UC-ID shows the parameter that it is called LCID and is defined as RNC ID + SAC. This so-called LCID is not used to position the user equipment. This UC-ID is also not used by user equipment and is needed for the correct functioning of the reference network (CN, Core Network).

LTE

LTE, LONG-TERM EVOLUTION - Fourth-generation mobile network, literally: Long-term development (strictly speaking, LTE is an ever third generation of communication, and is denoted as 3G LTE, i.e. long-term development of third-generation networks. The fourth generation can only be called LTE Advanced networks. ). LTE networks can be deployed in 44 frequency bands (while in the ranges 33-44 there is a temporary separation of the channels (TDD, TIME DIVISION DUPLEX), i.e. reception and transmission occur in one range, but not at the same time). Ukraine has long suggest that LTE technology attracts operators. But it is not yet known when it can be implemented in our country. The following ranges are used in Russia:

room	Name range	Range to transfer, MHz	Range on reception, MHz
7	2600	2500-2570	2620-2690
20	800	832-862	791-821
38	TDD 2600.	2570-2620
40	TDD 2300.	2300-2400

If we talk about the parameters that define the cell in LTE networks, then everything is somewhat different. We will need PLMN ID (MCC and MNC), as well as the following parameters:

eNodeB. - Analogue of the base station in LTE. GSM is called BTS, and in UMTS Nodeb.
E-UTRAN - Evolved Universal Terrestrial Radio Access Network, a network of extended universal ground access, the name of the LTE network data transmission interface.

Definitely identifies the cell here a bunch of MCC-MNC-ECI parameters (PLMN ID-ECI). As you can see, no LAC is provided in LTE networks. This is caused by the fact that the data network in LTE is extremely simplified and consists only of the network of base stations (ENodeB) and the dedicated packet data core. No switches (MSC, Mobile Switching Center), Basic Station Controllers (BSC, Base Station Controller) or Radio Controller Controllers (RNC, Radio Network Controller) are not here, and their functions are assigned to the Basic Stations of ENodeB. However, the LAC analogue in the LTE network also exists - this is TAC. However, it is no longer involved in hierarchical numbering of honeycombs (moreover, cells on a single base station may have a different TAC) and needed to correctly track the location of the user equipment (UE, User Equipment - analog MS from GSM) - when switching a UE to another tracking zone The procedure for updating the tracking zone (Tracking Area Update) occurs. TAC in LTE networks serves to logically divide the network on the tracking zone, unlike the LAC, which is due, rather, the physical separation of the network.

About GSM standard

GSM (from the name of the Groupe Spécial Mobile group, later renamed Global System for Mobile Communications) (Russian System for Mobile Communications) - Global Digital Standard for Mobile Cellular Communication, with the separation of the frequency channel on the TDMA principle and the average degree of safety. Designed under the auspices of the European Telecommunication Standardization Institute (ETSI) in the late 80s.

General

GSM refers to second generation networks (2 generation) (1G - analog cellular communication, 2G - digital cellular communication, 3G - broadband digital cellular communication, commutable multipurpose computer networks, including Internet).

Cell phones are available for 4 frequency ranges: 850 MHz, 900 MHz, 1800 MHz, 1900 MHz.

Depending on the number of bands, the phones are divided into classes and frequency variation depending on the region of use.

One-band - the phone can work on one of the frequencies. Currently, it is not available, but it is possible to manually select a certain frequency in some phone models, such as Motorola C115, or using the phone's engineering menu.

Dual Band - for Europe, Asia, Africa, Australia 900/1800 and 850/1900 for America and Canada.

Three-band (Tri Band) - for Europe, Asia, Africa, Australia 900/1800/1900 and 850/1800/1900 for America and Canada.

Quad Band - Support all ranges 850/900/1800/1900.

GMSK is used in the GMSK standard. Modulation with a value of the normalized BT band - 0.3, where B is a filter strip width of minus 3 dB, T is the duration of one bit of a digital message.

GSM is currently the most common communication standard. According to the GSM Association (GSMA), this standard accounts for 82% of the global mobile market, 29% of the world's population uses GSM global technologies. GSMA currently includes operators of more than 210 countries and territories.

Stages of development

GSM first meant Groupe Spécial Mobile, by the name of the analysis group, which created the standard. Now he is known as the Global System for Mobile Communications (Global System for Mobile Communications), although the word "Communication" is not included in the reduction. The development of GSM began in 1982 by a group of 26 European national telephone companies. The European Conference of Postal and Telecommunications Administrations (CEPT), sought to build a single Cell system of the 900 MHz for all European countries. The rare celebration of the European Union, the achievements of GSM became "one of the most convincing demonstrations which cooperation in the European industry can be achieved in the global market."

In 1989, the European Telecommunications Institute of Standards (ETSI) was responsible for the further development of GSM. In 1990, the first recommendations were published. The specification was published in 1991.

GSM commercial networks began to operate in European countries in mid-1991 GSM developed later than the usual cellular communication and in many ways it was better constructed. North-American analogue - PCS, raised standards from its roots including TDMA and CDMA digital technologies, but for CDMA, the actually increased opportunity of service was never confirmed.

1982 (Groupe Spécial Mobile) - 1990 Global System for Mobile Communications. The first commercial network in January 1992 is digital standard, supports data transfer rate to 9.6 kbps. Fully outdated, the production of equipment under it is discontinued.

In 1991, the services of the GSM 1 phase 1 standard were introduced.

They include:

Call Forwarding (Call Forwarding).

The ability to transfer incoming calls to another telephone number in cases where the busy number or subscriber does not respond; When the phone is turned off or is outside the zone of network action, etc. In addition, it is possible to redirect faxes and data.

Call Barring. Ban on all incoming / outgoing calls; ban on outgoing international calls; Ban on incoming calls, with the exception of intranets.

Call Waiting (Call Waiting). This service allows you to take an incoming call during an already ongoing conversation. At the same time, the first subscriber will still be in touch, or a conversation with it can be completed.

Call Holding. This service allows, without breaking the connection with one subscriber, call (or respond to an incoming call) to another subscriber.

Global Roaming (Global Roaming). When visiting any of the countries with which your operator has signed the appropriate agreement, you can use your GSM cell phone without a number of number.

GSM Phase 2 is adopted in 1993 Digital Standard, supports data transfer rate to 9.6 kbps. Since 1995, includes a range of 1900 MHz. The second stage of development GSM - GSM "Phase 2", which ended in 1997, provides for such services:

Calling Line Identification Presentation. With an incoming call, the caller number is displayed on the screen.

Anti-Security Restriction (Calling Line Identification Restriction). With this service, you can prohibit the definition of your own number when connecting to another subscriber.

Group call (Multi Party).

The teleconference or conference communication mode allows you to combine up to five subscribers to the group and negotiate between all members of the group at the same time.

Creating a closed group to ten subscribers (Closed User Group). Allows you to create a group of users whose members can also be associated with each other. Most often, companies providing terminals to their employees are resorted to this service.

Information on the cost of the conversation. This includes a timer that considers time on the line, and the call counter. Also, thanks to this service, you can check the remaining loan. Another service is possible: "Advice of Charge". At the request of the user, the cost check and the duration of the conversation at the time when the device is connected.

Alternative Line Service. The user can purchase two numbers that will be attributed to one SIM module. In this case, the connection is performed on two lines, with the provision of two accounts, two voice boxes, etc.

Short text messages (Short Message Service). The possibility of receiving and transmit short text messages (up to 160 characters).

Voice Mail system. The service allows you to automatically translate incoming calls to a personal answering machine (voice mail). You can use this only if the Subscriber has activated Call Forwarding Service.

GSM Phase 2 is considered outdated; But since the GSM standard implies backward compatibility, the old equipment of base stations and telephones can work (and work) in modern networks.

The next stage of development of the GSM 2+ Phase 2+ standards is not associated with a specific year of implementation. New services and functions are standardized and implemented after preparation and approval of their technical descriptions. All works under the Phase 2+ stage were conducted by the European Telecommunication Standardization Institute (ETSI). The number of services already implemented and under approval exceeds 50. Among them, the following can be distinguished:

improved SIM card software;

improved full-speed EFR speech coding (Enhanced Full Rate);

the ability to interact between GSM and DECT systems;

increasing the data transfer rate thanks to the GPRS packet transmission (General Packet RadioService) or by the data transmission system for Switched HSCSD channels (High Speed \u200b\u200bCircuit Switched Data).

Services

GSM provides support for the following services:

Data transfer services (synchronous and asynchronous data exchange, including batch data transmission - GPRS). These services do not guarantee the compatibility of terminal devices and provide only the transmission of information to them and from them.

Transfer of speech information.

Short Message Transmission (SMS).

Transfer fax messages.

Additional (optional provision) services:

Definition of the caller and restriction of such a definition.

Unconditional and conditional call forwarding to another number.

Waiting and hold call.

Conference Communication (simultaneous speech link between three and more moving stations).

Ban on user-defined services (international calls, roaming calls, etc.)

and many other services.

Advantages and disadvantages

Advantages of the GSM standard:

Smaller compared to the analog standards (NMT-450, AMPS-800) sizes and weight of telephone sets with greater operation time without recharging the battery. This is achieved mainly due to the base station equipment, which constantly analyzes the signal level received from the subscriber's apparatus. In cases where it is higher than the required, the command is automatically resolved to reduce the radiated power.

Good communication quality with sufficient location density base stations.

Large network capacity, the possibility of a large number of simultaneous connections.

Low level of industrial interference in the data of frequency bands.

Improved (compared to analog systems) protection against eavesdropping and illegal use, which is achieved by applying encryption algorithms with a shared key. [Specify]

Effective encoding (compression) speech. The EFR-technology was developed by Nokia and subsequently became an industrial coding / decoding standard for GSM technology. [Specify]

Widespread, especially in Europe, a large selection of equipment. To date, the GSM standard supports 228 operators officially registered in the Association of GSM operators from 110 countries.

The possibility of roaming. This means that the subscriber of one of the GSM networks can use a cell phone number not only at home, but also move around the world moving from one network to another without parting with its subscriber number. The transition process from the network to the network is automatically, and the user of the GSM phone does not have the need to notify the operator in advance (in networks of some operators, restrictions on the provision of roaming to their subscribers can be obtained, more detailed information can be obtained directly to your GSM operator)

The disadvantages of the GSM standard:

Speech distortion with digital processing and transmission.

Communication is possible at a distance of no more than 120 km from the nearest base station even when using amplifiers and directed antennas. Therefore, to cover a specific area, you need a greater number of transmitters than in NMT-450 and AMPS.

Standards and radio interface

GSM standards are created and published by the European Telecommunications Standards Institute. Documents are designated GSM NN.NN, for example, the standard is widely known on the GSM SIM GSM 11.11 card.

The GSM standard defines 4 range of work (there is still the fifth):

900/1800 MHz (used in Europe, Asia)

GSM-900 GSM-1800 characteristics

MS transmission frequencies and reception BTS, MHz 890 - 915 1710 - 1785

Frequencies of receiving MS and BTS transmission, MHz 935 - 960 1805 - 1880

Duplex transfer frequency and transmission frequencies, MHz 45 95

The number of frequency communication channels with a width of 1 communication channel in 200 kHz 124 374

Communication channel bandwidth, kHz 200 200

Digital mobile standard in the frequency range from 890 to 915 MHz (from the phone to the base station) and from 935 to 960 MHz (from the base station to the phone). The number of real communication channels is much more than written above in the table, because there is also a temporary separation of TDMA channels, i.e. on the same frequency, several subscribers can work in time.

In some countries, the GSM-900 frequency range has been expanded to 880-915 MHz (MS -\u003e BTS) and 925-960 MHz (MS<- BTS), благодаря чему максимальное количество каналов связи увеличилось на 50. Такая модификация была названа E-GSM (extended GSM).

Modification of the GSM-900 standard, a digital mobile standard in the frequency range from 1710 to 1880 MHz.

Features:

Maximum radiated power of mobile phones GSM-1800 - 1W standard, for comparison, GSM-900 - 2W. More continuous operation without recharging battery and reducing radio emission.

High tank network, which is important for large cities.

The possibility of using telephone sets operating in GSM-900 and GSM-1800 standards at the same time. Such a device operates on the GSM-900 network, but, falling into the GSM-1800 zone, shifts manually or automatically. This allows the operator to use the frequency resource more efficiently, and clients - save money due to low tariffs. In both networks, the subscriber uses one number. But the use of the device in two networks is possible only in cases where these networks belong to one company, or between companies operating in different ranges concluded a roaming agreement.

The GSM 900-1800 network is a single network, with a general structure, logic and monitoring in which the phone does not switch anywhere. Manually you can only prohibit use one of the ranges in test or very old devices.

The problem is that the coverage area for each base station is significantly less than in the GSM-900, AMPS / DAMPS-800, NMT-450 standards. A greater number of basic stations are needed. The higher the radiation frequency, the greater the penetrating ability (characterized by the T.N. Skin-layer depth) radio waves and the less the ability to reflect and turn the obstacles.

The GSM communication range is limited to the Timing Advance signal delay and is up to 35 km. When using the Extended Cell mode, it increases to 75 km. Almost achievable only in the sea, desert and mountains.

850/1900 MHz (used in the USA, Canada, individual countries of Latin America and Africa)

GSM-850 GSM-1900 Characteristics

MS transmission frequencies and BTS reception, MHz 824 - 849 1850 - 1910

Reception frequencies and BTS transmission, MHz 869 - 894 1930 - 1990

Duplex transfer frequency and transmission frequencies, MHz 45 80

GSM structure

Main article: GSM Core Network

GSM network structure

The GSM system consists of three main subsystems:

basic Station Subsystem (BSS - Base Station Subsystem),

switching subsystem (NSS - Network Switching Subsystem),

maintenance Center (OMC - Operation and Maintenance Center).

A separate GSM equipment class highlighted terminal devices - mobile stations (MS - Mobile Station), also known as mobile (cellular) phones.

Subsystem of base stations

Antennas of three basic stations on the mast

commons: images of GSM base stations on wikisklad?

BSS consists of actually base stations (BAST - Base Transceiver Station) and base stations controllers (BSC - Base Station Controller). The area covering the GSM network is divided into hexagonal cells. The diameter of each hexagonal cell can be different - from 400 m to 50 km. The maximum theoretical radius of the cell is 120 km, which is due to the limited feature of the synchronization system to compensate for the signal delay time. Each cell is covered by one BTS, with the cells partially overlap each other, thereby saving the possibility of transmitting MS maintenance when moving it from one cell to another without a connection breaking (Mobile phone maintenance transmission (MS) from one base station (BTS) to another At the time of the transition of the mobile phone, the limit of the current base station during a conversation, or the GPRS session is called the Handover technical term). Naturally, in fact the signal from each station spreads, covering the area in the form of a circle, but when the correct hexagons are obtained. Each base has six adjacent due to the fact that the tasks of planning stations include such as the minimization of the signal overlapping zones from each station. Larger number of neighboring stations than 6 - no special benefits. Considering the boundaries of the signal covering from each station already in the overlap zone, just get hexagons.

The base station (BTS) provides reception / transmission of the signal between the MS and the controller of the base stations. BTS is autonomous and built according to the modular principle. The directional antennas of base stations can be located on the towers, roofs of buildings, etc.

The base stations controller (BSC) controls the connections between BTS and the switching subsystem. Its powers also include managing compounds, data rate, radio channel distribution, statistics collection, various radio application, assignment and management of Handover procedure.

Switching subsystem

NSS is built from the following components:

Switching Center (MSC - Mobile Switching Center)

MSC controls a specific geographic area with BTS and BSC located on it. Connects the connection to the subscriber and from it within the GSM network provides an interface between GSM and PSTN, other radio networks, data networks. Also performs call routing functions, call management, reinforcement handling when moving MS from one cell to another. After the MSC call is completed, it processes the data on it and transfers them to the calculation center to form an account for the services provided, collects statistical data. MSC also constantly monitors the position of MS using data from HLR and VLR, which is necessary to quickly find and establish a connection with MS if it is called.

Home Register of Location (HLR - Home Location Registry)

Contains the database of subscribers attributed to it. This contains information about the services provided to this Subscriber, information about the status of each subscriber necessary if it is called, as well as the International Mobile Subscriber ID (IMSI - International Mobile Subscriber Identity), which is used to authenticate the subscriber (using AUC). Each subscriber is assigned to one HLR. The HLR data has access to all MSC and VLR in this GSM network, and in the case of firewall - and MSC other networks.

Guest register Location (VLR - Visitor Location Registry)

VLR provides MS monitoring from one zone to another and contains a database of moving subscribers currently in this zone, including subscribers of other GSM systems - so-called reameries. The subscriber data is removed from the VLR if the subscriber has moved to another zone. This scheme reduces the number of requests for HLR of this subscriber and, therefore, the call service time.

Equipment Identification Register (EIR - Equipment Identification Registry)

Contains a database needed to establish MS IMEI authentication (International Mobile Equipment Identity). Forms three lists: white (allowed to use), gray (some problems with MS identification) and black (MS prohibited for use). Russian operators (and most of the CIS operators) use only white lists, which does not allow once and permanently solve the problem of theft of mobile phones.

Authentication Center (AUC - Authentification Center)

Main article: GSM Security

The subscriber is authenticated here, or rather - SIM (Subscriber Identity Module). Network access is allowed only after passing the SIM authentication procedure, in the process of which with AUC on MS, a random number of RAND comes, after which the number of Rand Ki key for this SIM is encrypted on AUC and MS for this SIM using a special algorithm. Then with MS and AUC on MSC, "signed responses" - Sres (Signed Response) are returned, which are the result of this encryption. On MSC, the responses are compared, and in case of their coincidence, authentication is considered successful.

OMC subsystem (Operations and Maintenance Center)

Connected to the rest of the network components and provides control of the quality of operation and managing the entire network. Processes emergency signals in which personnel intervention is required. Provides network status checking, the possibility of passing a call. Software updates on all network elements and a number of other functions.

Wikipedia material - free encyclopedia.

GSM network networks do not cease to worry the question of sensitivity of various devices. Do not confuse the concept of sensitivity of the receiving part and the power of the transmitting. On the Internet, you can meet both people convinced that different devices are accepted in different ways, and those who claim that the concept of sensitivity, regarding GSM phones, a typical myth. Is it so?

First, briefly let's figure it out in the basic concepts that no one has questions.
So, simplistic speaking, the cell phone is a duplex radio station leading radio exchange at different frequencies. Such frequencies, according to the GSM standard, can be 124. At which frequency work is underway, the operator determines.

Base Station - Base Station (BS) transmits, and the phone - Mobile Station (MS) takes at frequencies of 935.2-959.8 MHz. Mobile phone transmits, and the base station receives at frequencies of 890.2-914.8 MHz.

Http://www.mobile-review.com.
If you are covered with an antenna with a hand during a conversation, the power also increases, since the signal is weakened. Considering that the phones have become small in size, cover the antenna with the hand is very easy. This changes the sensitivity of the device at least 4-5 dB. And as the tests of all modern phones show the differences between them just stacked in the same 4-5 dB. In turn, the tests of 4-5 dB fit into a statistical error, the term sensitivity ceases to be objective and passes into the subjective plane.

Http://www.ixbt.com.
Sensitivity, as well as the characteristic of the apparatus - the concept is completely conditional. Apparatuses from one batch may have different sensitivity. It all depends on the setting. According to the instructions, the scatter of values \u200b\u200bfor the same model can reach 4DB.

Http://www.onliner.by.
We are almost in the center of the cell. The phone is kept correctly. Do not close your hand with an antenna from above. And what do we see? And the fact that the level is -51 ..- 53db. Now we have a telephone on the soft surface of the sofa almost there, where he kept in his hand. WHAT IS IT??! We already have -44 ..- 45DB !!! Great. Take tel in hand. Fully close your palm antenna, already -60! -62!

To all of the above, it is necessary to add that the parameters discussed for a specific phone model are very difficult to find. Such information may simply be absent in the operating instructions, and the trust coefficient to it is quite low. Phone manufacturers often overestimate the characteristics, explaining it with their "more reliable" methods of measurement. Add to this stipulated by the standard, significant variation of the characteristics even in the phones of one series. That's the situation. After all this, you can trust subjective estimates from various sources or not?

Optionally, the base stations controller allows you to activate the mode at which it is possible to use the terminal at a distance of 120 km. From BS, but with this number of traffic channels on one carrier decreases to four. This mode is called extended cell (Extended Cell). On the territory of our region, its use is not effective, which is due to complex terrain. For example, Astrakhan - GSM successfully applies extended cells on flat sections and for coating p. Volga.

So how do you choose a phone model that will best work in an unstable connection zone?

I think that first of all you need to pay attention to the functionality of the phone, convenience of use, design and, finally, the price. And then - how lucky. In the zone with a normal signal level, the features of the parameters and the settings of the phone will not be displayed. In the zone of an unstable connection, a weak signal, if you are lucky and a phone with a more favorable setting option, it will work a little better, if not lucky, the connection will be slightly worse or it will not be at all. In any case, in the zone of unstable communication it is useful to help your phone, connecting an external directional antenna or at least Hands Free headset. After all, it is impossible to demand compensation for all disadvantages that have a cellular operator service area only from a small phone.

For reference:

Decibel (dB) - logarithmic units widely used in radio engineering to express the relationship of two values. The ratio of voltages (U) and capacities (P) of two signals in decibels can be expressed as follows:
N \u003d 20 log (U1 / U2) \u003d 10 log (P1 / P2)

If a certain reference absolute value is used as one of the values, it is possible to express absolute values \u200b\u200bin the logarithmic units. For example, if you accept the power of 1 MW for the reference value, then the other absolute power values \u200b\u200bcan be expressed in logarithmic units<дБм> (Decibel to Millivatt), which are often used in radio engineering. In this case, positive values \u200b\u200bcorrespond to the levels exceeding the reference value, and the negative levels are below the reference value.

Depending on the number of ranges, mobile phones are divided into classes and frequency variations depending on the region of use, since different frequency ranges for GSM networks are standardized historically in different parts of the world. Phones are:

Single-range (Single Band - The phone can work in one frequency band. Currently not produced, but it is possible to manually select a specific frequency range in some phone models, such as Motorola C115, or using the phone's engineering menu.

Dual-band (Dual Band) - 900/1800 MHz (for Europe, Asia, Africa, Australia - these 2 frequency range for GSM networks are standardized in this region), or 850/1900 MHz (for America and Canada - In Western Hemisphere, the frequency ranges other than Europe and another world, because by the time the European standard adoption in the new light of the radio frequency band 900 and 1800 MHz has already been distributed under other goals).

Treated-band (Tri-Band) - 900/1800/1900 MHz (for Europe, Asia, Africa, Australia) and 850/1800/1900 MHz (for America and Canada).

Four-range (Quad-Band) - 850/900/1800/1900 MHz, which support all frequency ranges (that is, such phones are the most universal - they can work almost anywhere in the world, where there is any GSM network).

The GSM commercial networks began to operate in European countries in the middle of the GSM, developed later than the analog cellular communication and in many respects was better designed. North-American Analogue - PCS, raised standards from its roots, including Digital TDMA and CDMA technologies, but for CDMA, the potential improvement in the quality of service was never confirmed.

GSM PHASE 1.

1982 (Groupe Spécial Mobile) - 1990 Global System for Mobile Communications. The first commercial network in January is a digital standard, supports data transfer rate to 9.6 kbps. Fully outdated, the production of equipment under it is discontinued.

In 1991, the services of the GSM 1 phase 1 standard were introduced.

Subsystem of base stations

BSS consists of actually base stations (BAST - Base Transceiver Station) and base stations controllers (BSC - Base Station Controller). The area covered by the GSM network is divided into conditional hexagons, called honeycomb or cells. The diameter of each hexagonal cell can be different - from 400 m to 50 km. The maximum theoretical radius of the cell is 120 km, which is due to the limited feature of the synchronization system to compensate for the signal delay time. Each cell is covered by one base station located in its center, while the cells partially overlap each other, thereby saving the possibility of transferring maintenance without breaking the connection when the subscriber is moved from one cell to another. Naturally, in fact the signal from each station spreads, covering the area in the form of a circle, and not a hexagon, the latter is only a simplification of the representation of the coating zone. Each base station has six adjacent due to the fact that in the tasks of the planning planning stations included minimizing the cost of the system. A smaller number of neighboring base stations would lead to a larger coating zones in order to avoid the "dead zones", which in turn would require a more dense location of the base stations. A greater number of neighboring base stations would lead to excessive costs at additional stations, while the winning from reducing the zones of the rehearse would be quite minor.

Extended Cell GSM How Works. How the GSM networks or brief bonds are working. Cable and antenna adapters

Introduction

A bit of theory

I see, but I do not hear at all!

Dance with cellotov

Extended Cell.

Attention, Zhuliki

Final word

Activating the NetMonitor menu for various phone models:

Nonitorizing programs for smartphones based on Android OS:

Detailed description of common types of mobile networks and display in NetMonitor:

GSM.

GSM-1800.

Umts.

LTE

GSM PHASE 1.

Subsystem of base stations

Switching subsystem

Switching Center (MSC - Mobile Switching Center)

Home Register of Location (HLR - Home Location Registry)

Guest register Location (VLR - Visitor Location Registry)

Equipment Identification Register (EIR - Equipment Identification Registry)

Authentication Center (AUC - Authentification Center)

Last

It is necessary to know