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Basic cellular communication standards. How to determine cellular frequency using a smartphone

Development of standards GSM 900, GSM E900, GSM 1800 contributed to the improvement of communication channels, but did not solve the problem of access to the Internet at the level required by modern people.

These standards belonged to the second generation (2G), in which the EDGE and GPRS protocols were used for data transmission, which made it possible to achieve speeds of up to 473.6 Kbps - catastrophically low for a modern user.

To date standards cellular communication One of the most important requirements is the data transfer speed and signal purity. Obviously, this affects the development of the mobile operator market. So, at one time, 3G networks appeared in Russia, which won the massive attention of users. And now it is for this reason that the number of people who choose 4G is increasing.

Feature of the UMTS standard

The main feature that distinguishes the UMTS standard from GSM is that the use of WCDMA, HSPA+, HSDPA protocols allows users to access higher quality mobile Internet. At speeds from 2 to 21 Mbit/sec, you can not only transfer more data, but even make video calls.

UMTS covers more than 120 largest Russian cities. This is the standard in which the currently popular mobile operators (MTS, Beeline, MegaFon and Skylink) provide 3G Internet service.

It's no secret that high frequencies are more efficient for data exchange. However, Russia has its own nuances that make it impossible to use, for example, UMTS frequency 2100 MHz in some regions.

The reason is simple: frequency UMTS 2100, which is actively used for 3G Internet, quickly sits down on obstacles. This means that a high-quality signal is hampered not only by distances to base stations, but also by increased vegetation. In addition, some regions are practically closed to this frequency due to the operation of air defense systems. Thus, in the South-Western part of the Moscow region there are several military bases, and accordingly, an unspoken taboo has been introduced on the use of this frequency.

In such a situation, for 3G Internet it is used UMTS 900. Waves in this frequency range have higher penetrating power. At the same time, at this frequency the data transfer rate rarely reaches 10 Mbit/sec. However, considering that just a few years ago many cities could not even think about Internet coverage, this is not so bad.

On this moment with the popular UMTS900 show excellent Huawei results E352 and the more stable version E352b, as well as E372, E353, E3131, B970b, B260a, E367, E392, E3276.

LTE: in what ranges will the future standard operate?

The logical development of UMTS was the development in 2008-2010. LTE is a new standard whose goal is to increase signal processing speed and throughput, and technically– simplify the network architecture and thereby reduce data transfer time. In Russia, the LTE network was officially launched in 2012.

It is LTE technology that determines development in our country mobile internet new generation – 4G. This means access to online broadcasts, fast transfer of large files and other advantages of the modern Internet.

At the moment, 4G Internet is supported by the LTE 800, LTE 1800, LTE 2600 standards, using the LTE Cat.4, Cat.5, Cat.6 protocols. This allows, in theory, to obtain data transfer speeds of up to 100 Mbit/s for upload and up to 50 Mbit/s for reception.

High LTE frequencies become an ideal solution for regions where the population density is quite high and where such data transfer speed is very important. These include, for example, large industrial cities. However, if all operators begin to work only in the range LTE 2600– a problem with radio signal coverage will immediately arise.

Now residents of Moscow, St. Petersburg, Krasnodar, Novosibirsk, Sochi, Ufa and Samara can take advantage of 4G technology. In Russia, Yota became one of the first operators to develop the fourth generation of mobile standards. Now they have been joined by such large operators as Megafon and MTS.

Development is considered optimal today LTE 1800: this frequency is more economical and allows new companies to enter the market that offer services mobile communications. It is even cheaper to build networks at 800 MHz. Thus, it is possible to predict what exactly LTE 800 And LTE 1800 will be the most popular among operators and, accordingly, with you and me.

LTE frequencies of various mobile operators

- Megafon: frequencies LTE 742.5-750 MHz / 783.5-791 MHz, 847-854.5 MHz / 806-813.5 MHz, 2530-2540 MHz / 2650-2660 MHz, 2570-2595 MHz (license for Moscow and the Moscow region );

- MTS: frequencies LTE 720-727.5 MHz / 761-768.5 MHz, 839.5-847 MHz / 798.5-806 MHz, 1710-1785 MHz / 1805-1880 MHz, 2540-2550 MHz / 2660-2670 MHz, 2595 -2620 MHz (license for Moscow and the Moscow region);

- Beeline: frequencies LTE 735-742.5 MHz / 776-783.5 MHz, 854.5-862 MHz / 813.5-821 MHz, 2550-2560 MHz / 2670-2680 MHz.

Rostelecom: LTE frequencies 2560-2570 / 2680-2690 MHz.

Yota: LTE frequencies 2500-2530 / 2630-2650 MHz.

Tele2: frequencies 791-798.5 / 832 - 839.5 MHz.

Signal amplification at different frequencies

When you find yourself in an area of ​​uncertain signal reception or move a long distance away from your operator’s base station, without additional antenna not enough.

Directional Antennas UMTS 900 signal has a basic package and can significantly increase the level of communication. At the same time, not only the Internet connection becomes more stable, but also the quality of voice transmission during telephone conversation. You can't do without a UMTS 2100 antenna if you want to use the Internet while traveling: due to constant switching from tower to tower, the data transfer speed drops catastrophically.

Directed LTE antennas 800 And LTE 1800 antennas – best option to strengthen the 4G signal in the appropriate frequencies. These standards have higher signal penetration and range.

However, LTE 2600 has a higher data transfer speed, thanks to which 80% of users in Moscow have already switched to this standard. And purchase LTE 2600 antennas is a prerequisite for those who chose 4G LTE 2600 (Megafon, MTS, Beeline, Rostelecom, Yota) to get maximum Internet speed. AmplifierLTEsignal will guarantee stable data transmission at high frequencies.

Solutions from GSM-Repeters.RU

LTE 800

Mobile subscriber's directory (part 1)

This article describes some of the concepts used in mobile communications. Without delving into scientific and terminological accuracy, I propose, so to speak, an article based on the FAQ (frequently asked questions) of mobile subscribers. Since I don’t know how to write only in terms and definitions :-), all concepts are accompanied by personal comments using the example of mainly Moscow Operators, although much is applicable to regional ones. All concepts are considered through the prism of how this affects subscribers, special attention is paid to the shortcomings and hidden tricks of Operators, which are aimed at additional deduction of money from subscribers. And the Operators themselves talk about the advantages, sometimes embellishing the reality, as they do in unreliable advertising. Please post your questions, additions and comments in my guest book or on the iXBT forums.

Basic concepts of mobile communication

mobile connection- this is any radio communication that allows the subscriber to use it without being tied to a specific location: cellular, trunk (or trunking), paging, radiotelephones, radio extenders, walkie-talkies, etc. cellular- a type of mobile communication, organized according to the principle of cells or cells (cells), by placing base stations(BS) (Base Transceiver Station), which cover the local area. The totality of local territories is service area(ZO) Operator. The signal level in a particular location depends on the proximity to the BS, terrain, buildings, industrial interference and other factors. The signal from the BS is transmitted to switch and is processed by it.

Operators publish AO maps, for example, on their websites. Moscow Operators' maps are not very clear - firstly, they publish them without indicating the location of the BS (clumsily referring to secrecy), which reduces their information content, and secondly, sometimes only 3 gradations of signal strength are shown: no signal, zone of possible reception and reliable reception zone. Moreover, instead of the logical color scheme for clarity - white, light, dark, respectively - on some cards it’s white, dark, light. Maybe for an optical illusion? If you look at the map, everything is dark, but in reality, this is just a zone of possible communication :-).

Many regional Operators do not practice open secrets ;-). For example, a model map from the St. Petersburg Operator Fora - and the BS are indicated (they even publish a list of the exact addresses of their installation), and 7 signal gradations.

Cellular standards

A cellular communication standard is a system of technical parameters and agreements for ensuring the functioning of a cellular communication system. There are 4 cellular communication standards adopted in Russia. Much has already been written about them, for example, but I would like to focus on some points.


NMT-450i(Nordic Mobile Telephone) - old analog standard. In Moscow, this standard is supported by MCC (Moscow Cellular Communications). All Russian NMT Operators form the SoTel network (Russian cell phone). There is an opinion that the quality of NMT communications is poor. This is wrong. Basically, this opinion is imposed by dealers, most of whom connect only to Beeline and MTS because of their more profitable commissions from the Operator. There are much fewer MCC dealers, and MCC is less profitable for dealers. By the way, it would not hurt to pay more attention to working with MCC dealers. For example, this summer dealers more often advocated connecting to MTS, and in the fall to Beeline. By a “strange” coincidence, dealer remuneration from MTS in the summer was much greater than from Beeline, and in the fall it was the other way around :-). Returning to the quality of communication - this is a complex concept: coverage area, sensitivity, ease of dialing, sound quality, connection stability, etc., therefore the quality of communication must be considered according to individual parameters. All these parameters of the NMT-450i are no worse (at least) than those of digital standards. Sometimes NMT sound is criticized, but it’s not bad, it’s just different: yes, there is interference, noise, “grunting”. Sometimes poor indoor reception in densely built areas or “dirty” airwaves. But the sound itself is more natural, “live” and rich compared to digital standards; there is no digital “gurgling”, “croaking” and failures due to incorrect digitization of sound. If with a bad analog connection you can somehow understand the interlocutor, even through crackling and noise, but with a bad digital communications, when frames drop out and sound is digitized incorrectly, sometimes you can’t understand anything. The NMT connection is stable, rarely breaks, and in terms of coverage area, the NMT-450i standard has no equal at all. If you need communication from remote places, then this is what you need, especially with powerful phones, therefore, this standard will live for a long time in the vast expanses of Russia, with the gradual transition of NMT Operators to the GSM-450 standard. By the way, for some reason this standard is officially called GSM-400. The disadvantages of the NMT standard include the “binding” of the phone to the Operator, a small selection of phones, their large size, and inflated prices.

D-AMPS(Digital Advanced Mobile Phone Service) is a digital standard. In Moscow it is supported by Beeline-800. Quite popular in Russia, just like its analogue version AMPS.

GSM(Global System for Mobile communications) is a modern digital standard (main in many countries). In this standard phone number and all other information about the subscriber is recorded in SIM-card (Subscriber Identity Module), which is issued to the subscriber upon concluding a contract and can be inserted into any (unlocked) GSM device of the required range, which makes the device itself independent from the Operator. The GSM standard is divided into GSM-450/900/1800/1900 depending on the operating frequency. In Moscow, the GSM standard is supported by MTS (Mobile TeleSystems) and Beeline-GSM. MTS has a main GSM-900 network plus GSM-1800 base stations in problem areas (heavy load) - the center of Moscow, Leningradskoye Shosse and some others. Beeline-GSM has an initial GSM-1800 network, which now covers Moscow and the near Moscow region (in different directions - 20-50 km from the Moscow Ring Road). Then Beeline-GSM began to build the GSM-900/1800 network, which already covered almost the entire Moscow region. In 2001, in the Moscow region, Sonic Duo plans to put into operation the GSM-900/1800 network, as well as the MCC network GSM-450/1800.

The quality of GSM communication is generally good, but, for example, with MTS and Beeline, the quality of GSM sound is somehow flat (to my average consumer’s musical ear :-)), it seems that GSM sound is overly compressed. Low redundancy in GSM audio compression algorithms leads to poor GSM noise immunity - with interference, even small ones, the correct digitization of sound is disrupted and - see above. I don’t know about other Operators, but I wouldn’t like to believe that there is the same one in Moscow true GSM with unsurpassed connection quality:-). And if you take into account the sound quality of some modern GSM phones, or rather stamped crafts in a beautiful wrapper from some manufacturers, then the picture becomes completely sad.

CDMA(Code Division Multiple Access) is a modern digital standard that surpasses GSM in many technical characteristics. In Moscow, the CDMA standard supports Sonet (Personal Communications). In Russia, for some reason, the CDMA standard is certified only as “fixed”, although all subscribers use it, naturally, as mobile. Much has already been written about this, as well as about other CDMA misadventures in Russia, for example. Let's hope that CDMA in Russia will overcome the slingshots of officials focused on personal interests and instigated by other Operators. My subjective opinion about the quality of CDMA communication is excellent rich sound, stable connection. Disadvantages: not yet expensive phones, limited coverage area. CDMA has (or maybe already had?) another serious drawback - the phone is tied to the Operator (see below for more on this), but it turns out that this is not fatal. Recently, the Chinese company ZTE, under the strict leadership of the CDMA technology leader Qualcomm, released the world's first CDMA phone with a SIM card (!). This little unnoticed revolution may have started the transformation CDMA standard from “tied” to “untethered”. If CDMA really does get rid of lock-in, then given the technical advantages of this standard, it will become even more attractive. I would like to believe that communications officials, despite pressure from other Operators, will cancel their order designating this standard as “fixed” in Russia. Moreover, most likely, there is still no escape from CDMA technology - it seems that this technology will be used in the world in third generation communication networks.

"Linked" standards

The (D)AMPS, NMT-450i, CDMA standards are “tied” standards, more precisely standards in which the phone is “tied” to the Operator, i.e. the Operator flashes (programs) the phone itself (and not the SIM card, as in GSM ), which is a big disadvantage for subscribers, causes them a lot of inconvenience, makes the phone itself (and, consequently, the subscriber) completely dependent on the Operator, and the degree of this dependence can be different and, again, is dictated by the Operator. This makes it possible to inflate prices for phones (manufacturers and Operators of DAMPS phones do not abuse this, but NMT-450i and CDMA often do), as well as the possibility of introducing various slingshots.

Here are some typical situations and compare them for “tied” standards and for GSM, the nuances depend on the specific Operator:

The phone is broken

Attached— you take the phone to the service center, hand it in for repairs with all the ensuing “hemorrhoidal” consequences. While you are waiting for your phone to return to normal, the flow of your life is disrupted - your number does not function. And if the phone breaks down somewhere far from a repair civilization, then it’s really bad. If the phone is under warranty, then you may be given another phone with your number during the repair (by law - three days after the application, and even then not always), but for this you need to go only to certain service centers, for remote areas - “convenience” is obvious. By the way, as long as the phone is faulty, the subscription fee will still be ticking, or the expiration date of a card, for example, BI+, will approach (i.e., the mandatory traffic fee will increase). You can, of course, block your phone or even write an application to extend the card's term, but this is an additional hassle and is not always possible.

GSM- move the SIM card from the broken phone to another GSM phone (you can buy a used phone as a temporary place old model dollars for 20), and use your number as before. You can, without haste, send a broken phone for repairs or sell the faulty one and buy a new one. And someone will like a makeshift for 20 dollars :-).

You decide to change your phone (but keep your number)

Attached- buy a phone. If it’s a used one, then there may be difficulties - you can run into an active one (not yet disconnected), then they won’t connect it. If it is not active, then it is difficult to fully check its functionality - for example, you cannot call it. Next, you go to the Operator’s office, waste time, write papers and wait for the number to be “transferred” to you (to a used one or to a new one). You can go to the Operator with the old owner of a used phone, but few will agree to waste time on this.

GSM— buy a phone (new or used) and put your SIM card in it.

· You decided to connect with the same phone to another Operator (or temporarily use its services)

Attached— another Operator (with the exception of some CDMA Operators) will not connect your phone while the phone is listed as active with another Operator. The “unlinking” procedure takes time, for some Operators it takes a little time, for others (for example, MCC) it takes quite a long time. There can be no talk of any temporary connection.

GSM— insert a SIM card of another GSM Operator into your phone (unlocked, of course) and use it. For example, in another city it is often much cheaper to connect to a local GSM Operator than to use roaming. The only inconvenience is that the number will be different. But at least the local Operator can be used for local communication.

Have you decided to sell your phone?

Attached- of course, you can simply sell the phone without changing the owner, without further ado. But there is a chance that your former phone(or rather its number) may get stuck in some kind of story, and they will bother you as the legal owner of the phone. Therefore, it is better to cut off the ends - sell the phone officially through a change of owner or by terminating the contract and connecting the phone again. Needless to say, this comes with additional hassle and material costs.

GSM— take out your SIM card and sell the phone. You can easily buy another one in the same way. By the way, there is always a reason to change a GSM phone - new models appear constantly. Many models, modern, with a great design to suit every taste, technically sophisticated, some of them with excellent quality, including sound, tempting you to buy something new. DAMPS and NMT subscribers are deprived of such pleasure - they are forced to choose a phone from a dozen outdated models - the world's leading manufacturers no longer pay much attention to these standards.

So the shortcomings of “tied” standards are obvious. I repeat, I am pleased that the release of CDMA phones with a SIM card has begun, so there is a possibility that CDMA will no longer be a “tied” standard and it will only be a matter of overcoming the slingshots of Russian officials :-).

Tariff plans

Tariff plan (TP) - a system of tariffs and a set of services. Tariff plans There are advance and credit. For example, the main TPs of MTS and MSS are advance: there is money in the account - you say, it’s in the red - be healthy, also on BI+. Other Beeline TPs are credit, i.e. payment occurs monthly after conversations. Beeline allows conversations in credit, that is, when the guarantee fee has already been agreed upon and the account has a minus amount, sometimes hundreds of dollars. Therefore, Beeline strictly monitors the purity of the connection - it is almost impossible to connect anonymously (that is, under someone else’s name) (which is sometimes required). The credit system has a number of disadvantages:

  • Sometimes unscrupulous dealers connect subscribers using someone else's passport details. Subscribers pay off all the money in the account, get into the red until disconnected, and then the owners of these passports receive bills and have to sort it out. This is the so-called “connection for slaughter”.
  • The child “played” with the phone, the subscriber did not calculate the roaming charges while on vacation :-), and the newbie simply did not understand the tariffs and said a lot of money. Of course, you need to be careful, study contracts and tariffs, keep an eye on children, etc., but still...
  • Receiving an invoice at the subscriber's address (or at the Beeline office) causes some inconvenience for those subscribers who often move.
  • Current control over the expenditure of funds is impossible, Beeline subscribers on credit TPs talk “blindly”, all information about expenses will only be available when the bill arrives. There is not even information about the consumption of “free” minutes. Although this is not a feature of the credit system. After all, it would be possible to create an automated system for credit TPs, similar to ACCA in MTS, which would notify the subscriber about his current expenses.
  • The credit system is expensive for the Operator, since it is necessary to spend money on collecting debts, as well as incur losses from unpaid debts and “slaughter”. These costs, by the way, fall on the shoulders of other subscribers. The credit system has not justified itself for MSS - it previously also allowed subscribers to have large debts (even on advance payment plans!), but, apparently, it has become difficult to collect debts, and now MSS does not allow debt from subscribers, and has even begun to include “debt” telephones.
  • With the credit system, you have to pay a guarantee fee (deposit), which must be returned when the contract is broken, which is also troublesome - you have to go to the Beeline office, perhaps stand in line, terminate the contract, wait a few days, go again... By the way, for some reason The guarantee fee (deposit) in Beeline is subject to VAT, although according to the Law “On VAT” it should not.

There are also fans of the credit system due to the fact that the subscriber will not be disconnected, as with the advance system, if there is not enough money in the account (usually at the most inopportune moment :-)), but MTS has a useful service for this situation: “Promised payment” "- a subscriber over the phone can take out a loan of up to $10 with subsequent payment within 7 days - very convenient if the account runs out of money, but there is no way to pay yet. And if you carry an MTS Express Payment card with you or you have credit card, there will be no such problems at all.

The so-called card (prepaid) TPs - BI+, MSS-Sekunda, MTS-TAKSAfon - are a type of advance TP. The advantage is payment by cards, a clear account control system, the disadvantage is a limited range of services.

All TPs of Moscow Operators (with the exception of MSS-Conversational) have a subscription fee or other mandatory payments, for example, a minimum fee for traffic, explicit, as on MTS-Local or hidden, as on BI+. Traffic(traffic) is airtime, i.e. the time of using the phone, for a certain period of time (usually a month). Sometimes called traffic amount, spent on communications during this period.

Many Operators have corporate TPs intended for a group of subscribers, payment is made on one invoice. Such TPs are convenient and beneficial for subscribers of one organization or group of relatives. Recent changes in Beeline's corporate TPs have made them the most attractive - the minimum number of handsets on corporate TPs has been reduced from 25 to 10, really not subscription fee on a crooked number, low rates, and with Beeline-800 (DAMPS) all incoming calls are free. True, sometimes Beeline corporate subscribers complain about poor quality service.

Free threshold and per second billing

Free threshold for outgoing/incoming calls in seconds (BP out/in) is a non-chargeable interval, i.e., a period of time from the start of a conversation that is not charged by the Operator, in other words, the duration of a conversation for which no fee is charged. A useful thing - if someone called you by mistake, or if you are calling someone, and instead of the subscriber the caller ID or answering machine is turned on (when they are turned on, the time is counted down) or the person you need is not at home, then if you have a power supply, you will not have to pay for the failed conversation in a whole minute (on most TPs). In Beeline-800 for credit TPs, tariffs begin from the beginning of the connection, i.e. when the ringing tone starts. Monitoring the power supply on NMT and DAMPS phones is difficult, since they show the time not from the beginning of the conversation, but from the moment of connection.

MSS at most TPs has 10out/15in. Beeline's power supply is 9out/9in. Some people think that Beeline’s BP on BI+ is valid at the beginning of every minute, i.e. 1 minute 8 seconds is charged as 1 minute. This is not true, it was only like this on the old BI+GSM TP. MTS has a very small power supply - 5out/5in. It is difficult to fit into this time even with one phrase about “wrong dialing of a number.”

It should be taken into account that all Operators do not charge the time before the power supply, i.e. 5 seconds are already charged for MTS. And if we take into account the possible difference in the measurement of time by the Operator’s equipment and the subscriber’s device, then you can be sure that the MTS subscriber’s conversation was not charged only if the phone display shows 3 seconds (!) or less. I met a more mocking power supply only with NNS - Nizhny Novgorod Cellular Communications (GSM-900) - up to 3 seconds (!). But with NSS, the situation is smoothed out by the fact that its billing is 15 seconds, i.e. if you slightly missed the BP, then they will count 15 seconds, and not a minute, as on MTS. Those who are interested in the power supply on MTS can try to buy a SIM card from old MTS subscribers or subscribers of regional tariff plans, for example, RTK (they no longer connect through them), on which the power supply is 5 out/20 out. BP does not work for forwarded and long-distance calls.

By the way, the power supply problem would really be solved by introducing a real per second payment(i.e. from the first minute) or discrete-second (like NSS). So far, the only Moscow TP with real per-second payment is MSS-Sekunda. For MTS and Beeline-GSM, per-second billing starts from the second minute. On most MSS TPs, on all BI+ TPs, as well as on most other TPs for long-distance and forwarded calls, per minute billing, i.e. 1 minute 01 seconds of conversation will be counted as 2 minutes, i.e. the cost of a minute, by the way, turns out to be almost 2 times more expensive in these cases. By the way, for such TP, minute timers on phones are useless, which will only inform you that the next minute has passed. For such TPs, phones are suitable in which the per-minute signal operates several seconds ahead, and also better phones with a programmable signal interval, such as Motorola phones.

Straight and curved numbers

Cell phone numbers can be straight or crooked. Direct- these are ordinary city seven-digit (in Moscow) numbers, curves(or federal) - dial using codes 901, 902, 903 or others, from MGTS phones dial through intercity access via figure eight or through dialing service(SD) is free service Operators for calls to crooked numbers without dialing “eight” (it’s not always possible, and sometimes “eight” is busy). MTS and Beeline have an automatic SD with the need to additionally dial a mobile phone number in tone mode. Calling a number on a curve is sometimes problematic, since many payphones do not have a tone mode, which is necessary for calls via SD. MSS SD is “live”, like everything analogue :-), it is also planned to introduce automatic, through it you can call crooked numbers even from rotary telephones and from old payphones without using beepper(tone generator).

Advantages of a direct number:

  • Ease of dialing. There is no need to use the “8”, which is often busy (and sometimes completely blocked) or the dialing service (it is not always possible to use tone dialing).
  • You can call from any telephone and payphone.
  • Solid, prestigious, easy to remember.

Advantages of a curved number:

  • Lower price.
  • Caller ID works well.

Calls to crooked phones of Moscow Operators are free from MGTS phones (from seven-digit phones of JSC Electrosvyaz of the Moscow Region are paid). List of telephone series of Moscow Operators. To other crooked numbers, including those using codes 901, 902, calls from MGTS phones are paid, at approximately long-distance rates to the city where the Operator is “registered”.

Caller ID (Automatic Number Identifier)

More precisely in cellular communications it is called CLIP(Calling Line Identification Presentation). If such a service is available, the number of the subscriber calling you is displayed on the display of your mobile phone. In addition to its usual purpose - to know who is calling you, Caller ID is also useful for saving money. For example, depending on the number identified, the subscriber can answer or not answer, but forward the call, or answer within the BP, or call back from a landline phone, etc. Or in order to answer only on-net calls, since incoming mobile calls of the same Operator are free. Or look at the list of missed calls later if it was not possible to answer immediately. Operators guarantee that only mobile phones are identified, although in fact, most landline numbers are also identified on crooked numbers. On direct numbers, only mobile (and digital) phones are detected; Caller ID works well only on some direct series, for example, MTS 231 and 233, Beeline-GSM on series 130 (TP Super-GSM). In general, it is strange that Operators still do not have a full-fledged Caller ID. It is clear that there are some technical problems, including MGTS, but it’s high time to solve them. Since Operators still divide incoming calls into paid and free, then, in my opinion, Operators should provide Caller ID for free so that the subscriber has information about this. Although this is not a lot of money, nevertheless, the cost of Caller ID is up to 50% of the subscription fee for the phone, and this is a fundamental issue. But by and large, there should be civilized TPs with all free incoming calls (like MSS Unlimited-Incoming), since even with Caller ID it is not always possible to understand which Operator’s subscriber is calling you. For example, if the number 8-902-... is identified on the Caller ID of your mobile phone, this does not mean that this is an MTS subscriber. It is possible that this is a subscriber of a cellular non-Moscow Operator, i.e. incoming call from him will be paid (and outgoing calls to him are generally long-distance). You can, of course, look at the list of phone series of Moscow Operators, but you won’t learn it by heart.

AntiAON(CLIR) - allows you to hide your number from the called subscriber. Operators provide an anti-caller ID service, which hides the number only from mobile caller IDs. By the way, MSS telephones are not detected on MGTS caller numbers.

Roaming

Roaming- this is the ability to use a phone outside the Operator’s service area, but in the service area of ​​another Operator with whom there is a roaming agreement. Today, NMT Operators have the most extensive roaming in Russia, but GSM roaming is developing rapidly. In GSM roaming is automatic. If in this place There are several roaming Operators, then depending on the phone model and its settings, either the Operator with the strongest signal level is selected, or according to a preference list, or manually.

Roaming is a very convenient and useful service, but you shouldn’t use it unless absolutely necessary, at least for now. Today, roaming service is a source of constant complaints from subscribers to Operators. For Beeline-GSM, this is even aggravated by the fact that it is impossible to control your expenses with credit TPs, a surprise bill will arrive after you use roaming, and even with MTS, data from roaming comes with some delay, i.e. a situation is possible in MTS , when your account is already minus, and the phone has not yet been disconnected.

Operators and roaming partners often miscellaneous information about tariffs and services. Sometimes Operators do not bother to notify their roaming partners about changes. Often the Operator's directories contain outdated information, sometimes even incorrect Help numbers roaming partner, not to mention tariffs, power supply, rounding and other terms of service. Here, for example, is a fragment of a real response to a claim about incorrect deductions when roaming: “Vimpelcom cannot guarantee the accuracy of the information provided by the operator company providing roaming services. This information is constantly changing and depends on the services provided by the “guest network” operator.”.

For some regional Operators, the value of conventional units is underestimated (supposedly cheap :-)), for example, for Kuban-GSM, for some reason now “ue” is equal to 21 rubles, which introduces additional confusion in the recalculation of tariffs. When making an incoming call in roaming, the cost of a minute of conversation consists of two components: the fee for long-distance calls in the MTS network and the fee for an incoming call, which is set by the local Operator (sometimes it is not charged). It is also necessary to take into account the peculiarities of tricky tariffing when roaming such services as voice mail and forwarding, it is better to turn off all forwarding settings for the period of roaming.

The subscriber does not always have the opportunity to study all this information, especially for those who are constantly moving. Not all subscribers have the opportunity to constantly monitor the conditions of Operators and choose the optimal one for roaming. The difficulty of “debriefings” is that Operators send to the place of receipt to clarify information communication services, i.e. to the roaming partner. It turns out that the ends are in the water, since few subscribers will do this. For example, some of the Operators for some reason do not have a power supply, someone (for example, the independent Kyivstar-GSM) takes money for a failed conversation - for an answering machine message that the subscriber (i.e., you) is unavailable. This is an “excellent” service - while you are unavailable (for example, you are on the subway), then your money is debited, and at roaming rates (!), if they try to call you. Some of the Operators (Russian!) set exorbitant tariffs. For example, calls to Moscow for many Operators reach $2-2.5 per minute (and not necessarily from distant regions), and local calls for some roaming Operators are approximately the same, and, for example, in Khabarovsk and Novosibirsk local calls ( if you use the services of North-West GSM) for MTS subscribers cost about $3.60 per minute! It is better, if possible, to use the services of other MTS roaming partners, respectively DSS (Far Eastern Cellular Systems) and SSS (Siberian Cellular Systems), in this case the call will cost several times cheaper, but another Operator may work better in a particular location. In this case, it is better to install the Operator you need manually.

There are many unsuccessful examples of using roaming, as evidenced by numerous complaints from subscribers about incorrect (or incomprehensible) debiting of money when using roaming. It’s good if there is a meticulous subscriber who pays attention to this discrepancy, but how many more such “inaccuracies” are, naturally, not in favor of the subscriber, which have not yet been noticed by anyone? So it’s better not to use roaming unless absolutely necessary, and if you can’t do without it, then try to get maximum information about the tariffs and conditions of roaming in the regions where you are going, but this, however, does not guarantee the absence of misunderstandings when using roaming.

SMS

SMS(Short Message Service) - Short message service is a very convenient service for cellular subscribers that allows you to send short messages (up to 160 characters) text messages to other subscribers. This feature made pagers practically unnecessary, since, having a cell phone, you can use the same service, and for a fee comparable to the fee for paging service. And if you consider that with cell phone you can receive messages even if your phone is turned off or unreachable (get it later); transmit messages from it; that the cellular service area is much larger than the paging area (plus roaming); that for some modern telephones are not much larger in size than pagers; Since you can still talk on the phone, it becomes clear why the popularity of pagers has fallen sharply. Using SMS allows cellular subscribers reduce your expenses, since sending messages is much cheaper than a minute of conversation, and receiving messages is free (including in roaming). Some TPs charge a small monthly fee for SMS without taking into account the number of messages sent. There are many services for SMS users: various servers for sending messages from the Internet, including from the popular ICQ (program for Internet communication ICQ), you can send a message from a mobile phone to ICQ, to e-mail, you can send messages from a landline phone or payphone - through a special service operator (like a pager) or in tone mode - etc. With the development of e-commerce and other services, the popularity of SMS will increase.

The most developed SMS service is for the GSM standard (MTS and Beeline-GSM in Moscow). Beeline-800 (DAMPS) can only receive messages; MCC (NMT-450i) promised to introduce SMS service in September, but has not yet done so. To be able to send messages using a GSM phone, you must register the SMS center phone number specified in the MTS or Beeline-GSM subscriber directory. Unfortunately, competition between these companies sometimes interferes with subscribers - through these SMS centers you can only send messages to subscribers of the same Operator. To send messages from MTS to Beeline or vice versa, you must register the phone number of the SMS center of another Operator that has a roaming agreement with both MTS and Beeline-GSM, for example, the Tatar Operator TAIF-Telkom (+7902390000). By the way, roaming between MTS and Beeline-GSM would greatly help subscribers and overcome the current gaps in the coverage of each subscriber. In the meantime... While they are locking (encoding) phones from each other. Well, thank you for not charging calls to a subscriber of another Operator as international :-).

Creation mobile networks 2G generation, which was based on digital standards, was primarily due to the shortcomings of the first generation networks, which did not provide normal network capacity and high level protecting the confidentiality of conversations. Due to the fact that it has gained increasing popularity, the work of developers has become focused on improving the bandwidth of standards, as well as standardizing the network around the world, which would allow customers to travel across countries and, due to automatic roaming, always stay connected. Developers from Europe and America who worked on the creation digital standard communications at the global level, back in the early 90s they came to the conclusion that it was possible to realize their plans only with the help of digital methods of transmitting auditory information and controlling communications.

At that time, D-AMPS and CDMA networks from the USA, the JDC standard from Japan and the GSM standard of the global pan-European level were four types of 2G generation networks that could organize cells with a radius of up to 30 km. Now D-AMPS is having a hard time and in order to withstand at least some competition they are forced not only to reduce tariffs, but also to show those services that were not originally intended (for example, voice mail, auto-dialing and conference calling, automatic detection numbers, as well as information transfer and Internet access).

CDMA went about improving the privacy of conversations by compressing information in a digital speech coding system, as well as eliminating the problem of duplicates by assigning an identification number to each phone. Changing the device requires the mandatory participation of the cellular operator, since the information must be rewritten, because the subscriber's contact list and organizer are stored in the phone's memory. While maintaining the same cell sizes, the number of simultaneously calling subscribers in a cell increased to 1000. Phones with the same infrastructure are small in size, good quality sound, quickly transmit information (up to 14.4 kbit/s) and consume little energy. Currently common in North America and Korea. They are also available in Russia, but are not widely used and have limited roaming.

Communication standard 2G GSM

The most popular mobile communication today is the GSM (Global System for Mobile Communications) standard, created in 1991 in Europe and widely used throughout the world. For the purpose of mass application and the ability to modify the network without changing the basic functions, the operating experience gained over many years was taken into account mobile phones. Specifications GSM corresponded to up to 35 km radius of the network cell and up to 1000 calls simultaneously, the maximum power of phones was within 1V and up to 20V in stationary and automotive versions. Mobile terminals were characterized by their miniature size and the ability to work for a long time without recharging.

A feature of 2G communication standards is clear sound without interference, only slightly distorting timbre and intonation, and small swallowing of word fragments in case of instability and communication interference, as well as when weak signal. At the time this was a great achievement. During the conversation, when the subscriber did not speak but listened to the interlocutor, the transmitter turned off digital systems to save battery power and in order not to clog the airwaves, at this time the speaker heard artificial noise, which did not cause discomfort and was aimed at not creating the appearance of a lack of communication when the transmitter was turned off. To protect the confidentiality of conversations, encryption algorithms were complex and proprietary, updated frequently, and had different keys for each connection.

In the introduced GSM 1800 standard, in which the frequency range expanded and the cells became smaller, throughput increased significantly. Based on the experience of its operation in large cities, it became clear that, despite the total use of mobile communications, it remains possible to avoid network congestion. The frequencies used by GSM throughout the world correspond to 900 and 1800 MHz; in the USA, the range provided to operators is small and amounts to 1900 MHz (therefore, the American standard is called GSM 1900). CDMA and D-AMPS operators operate in the same range. The phones currently being produced work in all three GSM bands.

Users' need for fast information transfer and comfortable work the Internet increasingly pushed for the need to create a new communication standard, which prompted the development and creation of GPRS technology, which became a superstructure over the GSM standard. It made it possible to reach a reception speed of 40.2 kbit/s.

An important achievement of GSM phones was the linking of the number and phone book not to the device itself, but to a SIM card (Subscribe Identity Module), which can be moved from one phone to another, while your own number and contacts are transferred automatically. The card allows the operator to identify the subscriber and store up to 255 contact numbers in memory.

The services provided by GSM network operators have a wide range and allow you to use conference calls, call forwarding, enable and listen to voice connections, send and receive SMS, access the Internet directly from your phone via a WAP browser, use information services (such as receiving weather information, prices, required addresses and telephone numbers), as well as transmit information and faxes, etc.

The structure of GSM networks includes switching systems and base stations and subscriber telephones (MS).

The Network Switching System (NSS) is aimed at providing services to customers, servicing calls and switching connections. It consists of:

Cellular Switching Center (MSC), which works to establish connections between network users, mobile and fixed networks; MSC is the main element of the GSM network, since it is designed to control the operation of BTS and BSC within the service area;
- home location register (HLR), which provides storage of information about subscribers (location, list of connected services, etc.) related to this MSC;
- a visitor location register (VLR), containing information about active subscribers in the service area of ​​a particular MSC (data about home and guest subscribers of this MSC) and receiving information from the HLR;
- an authentication center (AUC), which serves as a source of subscriber identification and is aimed at preventing officially unauthorized access to the network, which, based on available information from the AUC and MS, begins the authentication procedure every time you use the phone, make a call or send an SMS;
- subscriber equipment identification register (EIR), which is an optional element and therefore is not present in all networks. However, it is a database that stores and secures mobile terminals' identification number information, which is used to block stolen or lost phones.

The Base Station System (BSS) performs the functions of the radio interface and includes two blocks:

The Base Station Controller (BSC), which is a high-capacity switch, controls such functions of GSM radio channels as radio channel assignment, finding information about cell configuration features and the transmission process between base stations user sessions;
- a base station (BTS), which controls radio communication with the subscriber’s phone and consists of the transceivers and antennas necessary to service each cell.

GPRS technology of the GSM standard additionally includes:

GPRS Subscriber Service Node (SGSN) - is a router that establishes sessions for transmitting information in packets and controls the movement of packets and charging for services already provided; packet data is directed towards the SGSN from the base stations;
- GPRS gateway node (GGSN), which is most often combined in a device with SGSN, is a network gateway that routes data outside the operator’s network.

The advantages of 2G generation networks were digital encryption of conversations, greater efficiency of the system itself compared to the previous generation, and the emergence of the ability to send text, multimedia messages, as well as messages with images. Thanks to digital encryption, 2G technology has become safer for both the sender and the recipient.

The life of a modern person cannot be imagined without mobile communications. The first “handheld handsets” were radiotelephones, which included the very first generation of 1G cellular communications, namely the NMT (Nordic Mobile Telephone) standard, which appeared on the world market in 1981.

LTE (Long-Term Evolution) technology is the main direction in the evolution of third generation (3G) cellular networks. In January 2008, the international association Third Generation Partnership Project (3GPP), which develops promising mobile communication standards, approved LTE as the next standard for a broadband mobile communication network after UMTS.

4G networks based on the LTE standard are capable of operating across almost the entire frequency spectrum from 700 MHz to 2.7 GHz.

LTE provides theoretical peak data rates of up to 326.4 Mbps from the base station to the user and up to 172.8 Mbps in the reverse direction.

Long Term Evolution technology is expected to lead to the emergence of qualitatively new mobile services: users will be able to receive video in real time High Quality, work with interactive services, etc.

In April 2009 LTE network was shown by Motorola at the CTIA Wireless exhibition. In May Swedish operator Telia demonstrated the world's first section of a cellular network built using LTE technology. Verizon, Bell and Telus are working on creating such networks.

This standard was developed by Intel Corporation, the world's largest microchip manufacturer. Accordingly, laptops will primarily be equipped with WiMAX chips. Most likely, over time, WiMAX will replace Wi-Fi, since Wi-Fi operates within a radius of several meters from the access point; mobile WiMAX has significantly greater coverage. And in addition, it allows the subscriber, if he is moving at a speed of up to 120 km/h, to switch between stations.

Summer 2009 In Russia, Russia's first wireless fast Internet network using Mobile WiMAX (4G) technology was launched into commercial operation. The service provider based on this network was Scartel, known under the Yota brand. The network provides high speed Internet access - up to 10 Mbit/s, at any time, anywhere in the coverage area and maintains a connection even while on the move, at speeds of up to 120 km/h. Residents of Moscow, St. Petersburg, Ufa, Krasnodar and Sochi have already received access to Yota.

The material was prepared based on information from open sources

This article is the first in a series of articles about cellular communications. In this series, I would like to describe in detail the principles of operation of second, third and fourth generation cellular networks. The GSM standard belongs to the second generation (2G).

The first generation of cellular communications was analog and is not used now, so we will not consider it. The second generation is digital and this feature has made it possible to completely replace 1G networks. A digital signal is more noise-resistant than an analog signal, which is a major advantage in mobile radio communications. Besides, digital signal In addition to speech, it allows you to transmit data (SMS, GPRS). It is worth noting that this trend of transition from analog signal on digital is characteristic not only of cellular communications.

GSM (Global System Mobile) is a global standard for digital mobile communications, with channel division by TDMA time and FDMA frequency. Developed under the auspices of the European Telecommunication Standardization Institute (ETSI) in the late 1980s.

GSM provides support for services:

  • GPRS data transfer
  • Voice transmission
  • Sending short messages SMS
  • Sending a fax

In addition, there are additional services:

  • Number identification
  • Call forwarding
  • Call waiting and holding
  • Conference call
  • Voice mail

GSM network architecture

Let's take a closer look at what elements the GSM network is built from and how they interact with each other.

The GSM network is divided into two systems: SS (Switching System) - switching subsystem, BSS (Base Station System) - base station system. SS performs the functions of servicing calls and establishing connections, and is also responsible for the implementation of all services assigned to the subscriber. The BSS is responsible for functions related to the air interface.

SS includes:

  • MSC (Mobile Switching Center) – GSM network switching node
  • GMSC (Gate MSC) – a switch that processes calls from external networks
  • HLR (Home Location Register) – database of home subscribers
  • VLR (Visitor Location Register) – database of guest subscribers
  • AUC (Authentication Cetner) – authentication center (subscriber authentication verification)

BSS includes:

  • BSC (Base Station Controller) – base station controller
  • BTS (Base Transeiver Station) – transceiver station
  • MS (Mobile Station) – mobile station

Composition of the SS switching subsystem

MSC performs switching functions for mobile communications. This center controls all incoming and outgoing calls coming from other telephone and data networks. These networks include PSTN, ISDN, public data networks, corporate networks, as well as mobile networks of other operators. Subscriber authentication functions are also performed in the MSC. The MSC provides call routing and call control functions. The MSC is responsible for switching functions. MSC generates the data necessary for tariffication of communication services provided by the network, accumulates data on completed conversations and transmits them to the billing center. MSC also compiles statistical data necessary for monitoring and optimizing the network. The MSC not only participates in call control, but also manages location registration and control transfer procedures.

In the GSM system, each operator has a database containing information about all subscribers belonging to its PLMN. In the network of one operator there is logically one HLR, but physically there are many of them, because This
distributed database. Information about the subscriber is entered into the HLR at the time the subscriber registers (the subscriber enters into a service contract) and is stored until the subscriber terminates the contract and is removed from the HLR register.
Stored information in HLR includes:

  • Subscriber identifiers (numbers).
  • Additional services assigned to the subscriber
  • Information about the subscriber's location, accurate to the MSC/VLR number
  • Subscriber authentication information (triplets)

HLR can be implemented as a built-in function in MSC/VLR or separately. If the HLR capacity is exhausted, then an additional HLR can be added. And in the case of organizing several HLRs, the database remains single - distributed. The subscriber data record always remains the only one. Data stored in the HLR can be accessed by MSCs and VLRs belonging to other networks as part of providing inter-network roaming to subscribers.

The VLR database contains information about all mobile subscribers currently located in the MSC service area. Thus, each MSC on the network has its own VLR. The VLR temporarily stores service information so that the associated MSC can serve all subscribers within the MSC's service area. HLR and VLR store very similar subscriber information, but there are some differences that will be discussed in the following chapters. When a subscriber moves to the service area of ​​a new MSC, the VLR connected to that MSC requests subscriber information from the HLR that stores that subscriber's data. The HLR sends a copy of the information to the VLR and updates the subscriber's location information. Once the information is updated, the MS can make outgoing/incoming connections.

To prevent unauthorized use of communication system resources, authentication mechanisms are introduced - authentication of the subscriber. AUC is a subscriber authentication center, consists of several blocks and generates authentication and encryption keys (passwords are generated). With its help, MSC verifies the authenticity of the subscriber, and when a connection is established, encryption of the transmitted information will be enabled on the radio interface.

Composition of the BSS base station subsystem

The BSC controls all functions related to the operation of radio channels in the GSM network. It is a switch that provides functions such as MS handover, radio channel assignment, and cell configuration data collection. Each MSC can manage multiple BSCs.

The BTS controls the radio interface with the MS. The BTS includes radio equipment such as transceivers and antennas that are needed to serve each cell in the network. The BSC controller controls multiple BTSs.

Geographical construction of GSM networks

Each telephone network needs a certain structure for routing calls to the required station and further to the subscriber. In a mobile network, this structure is especially important, since subscribers move around the network, that is, they change their location and this location must be constantly monitored.

Despite the fact that the cell is the basic unit of the GSM communication system, it is very difficult to give a clear definition. It is impossible to associate this term with an antenna or a base station, because There are different honeycombs. However, a cell is a geographical area that is served by one or more base stations and in which one group of GSM control logical channels operates (the channels themselves will be discussed in the following chapters). Each cell is assigned a unique number called a Cell Global Identifier (CGI). In a network covering, for example, an entire country, the number of cells can be very large.

A location area (LA) is defined as a group of cells in which the mobile station will be called. The subscriber's location within the network is associated with the LA in which the subscriber is currently located. The given area identifier (LAI) is stored in the VLR. When an MS crosses the boundary between two cells belonging to different LAs, it transmits information about the new LA to the network. This only happens if MS is in Idle mode. The new location information is not transmitted for established connection, this process will occur after the connection ends. If an MS crosses a boundary between cells within the same LA, it does not inform the network of its new location. On admission incoming call to the MS, the paging message is distributed within all cells belonging to the same LA.

The service area of ​​an MSC consists of a number of LAs and represents the geographical portion of the network under the control of one MSC. In order to route a call to an MS, information about the MSC's service area is also needed, so the service area is also monitored and information about it is recorded in a database (HLR).

A PLMN service area is a collection of cells served by a single operator and is defined as the area in which the operator provides radio coverage and access to its network to the subscriber. Any country may have several PLMNs, one for each operator. The definition of roaming is used when an MS moves from one PLMN service area to another. So-called intra-network roaming is a change of MSC/VLR.

The GSM service area is the entire geographical area in which a subscriber can access the GSM network. The GSM service area is expanding as new operators sign contracts to collaborate on customer service. Currently, the GSM service area covers, at some intervals, many countries from Ireland to Australia and from South Africa to America.

International roaming is a term that applies when an MS moves from one national PLMN to another national PLMN.

GSM frequency plan

GSM includes several frequency ranges, the most common: 900, 1800, 1900 MHz. Initially, the 900 MHz band was allocated for the GSM standard. Currently, this range remains worldwide. Some countries use extended frequency bands to provide greater network capacity. The extended frequency bands are called E-GSM and R-GSM, while the regular band is called P-GSM (primary).

  • P-GSM900 890-915/935-960 MHz
  • E-GSM900 880-915/925-960 MHz
  • R-GSM900 890-925/935-970 MHz
  • R-GSM1800 1710-1785/1805-1880 MHz

In 1990, to increase competition between operators, the UK began to develop new version GSM, which is adapted to the 1800 frequency range. Immediately after the approval of this range, several countries applied to use this frequency range. The introduction of this range increased the growth in the number of operators, leading to increased competition and, accordingly, improved quality
service. The use of this range allows you to increase the network capacity by increasing the bandwidth and, accordingly, increasing the number of carriers. Frequency band 1800 uses the following frequency ranges: GSM 1710-1805/1785-1880 MHz. Until 1997, the 1800 standard was called Digital Cellular System (DCS) 1800 MHz, currently called GSM 1800.

In 1995, the concept of PCS (Personal Cellular System) was specified in the USA. The main idea of ​​this concept is the ability to provide personal communication, that is, communication between two subscribers, and not between two mobile stations. PCS does not require that these services be implemented on cellular technology, but this technology is currently recognized as the most effective for this concept. The frequencies available for PCS implementation are in the 1900 MHz region. Since GSM 900 cannot be used in North America due to the frequency band being occupied by another standard, GSM 1900 is an option to fill this gap. The main difference between the US standard GSM 1900 and GSM 900 is that GSM 1900 supports ANSI signaling.

Traditionally, the 800 MHz band has been occupied by the TDMA standard (AMPS and D-AMPS) common in the United States. As in the case of the GSM 1800 standard, this standard makes it possible to obtain additional licenses, that is, it expands the scope of the standard to national networks providing operators with additional capacity.

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