Cellular communication standards: GSM. Cellular booster kits

01.02.2011

Uplink - a communication channel from a subscriber (phone or modem) to a base station of a mobile operator. Downlink - communication channel from the base station to the subscriber.

General table of radio frequencies

TELE2, a new operator for the Moscow region, has only LTE800, WCDMA2100, LTE2600 frequencies.

Accordingly, if you want to amplify the TELE2 signal, then you need to install 3G repeaters, because. only in this range there is voice communication.

3G frequency:

Cellular communication of the 3rd generation 3G / UMTS2100 in Russia operates at Uplink 1920 - 1980 MHz and Downlink 2110 - 2170 MHz.

Instead of a skylink, TELE2 currently uses these frequencies. Since there are not enough frequencies due to the growth of subscribers, they began to launch 3G at GSM900 and E-GSM frequencies, i.e. Uplink 880-915MHz and DownLink 925-960MHz.

Example 3G/UMTS900 for Moscow region (frequencies are indicated by DownLink, in UpLink everything is the same):

Both GSM and 3G cannot be in the same piece of frequencies at the same time, for example, like Megafon has the 2nd band in E-GSM frequencies. 3G has a frequency band of 5 MHz always and everywhere. In the Moscow region, Megafon has 3G / UMTS900 almost everywhere. MTS and Beeline are mainly used only in the South of the Moscow Region due to the military ban on operating on 2000 frequencies. (updated as of January 2015).

4G/LTE2600 frequency:

4G/LTE2500 - 4th generation communication, operates at frequencies of 2500-2700 MHz.

Information current as of January 2013.

FDD (frequency division duplex - frequency division of channels) is like incoming and outgoing channels in GSM go at different frequencies.

TDD (time division duplex - time division of channels) is outgoing and incoming channels on the same frequency!

Beeline got only 10 MHz.

TELE2 also received only 10 MHz. (look at Ros frequencies)

MTS - 35 MHz in the Moscow region and 10 MHz throughout the country.

And Megafon and Yota (this is the same holding) got as much as 65 MHz for two in the Moscow region and 40 MHz throughout Russia!

Through Yota in Moscow, only Megafon works in the 4G standard, in other regions - Megafon and MTS. Television (Cosmos-TV, etc.) will operate in the TDD range throughout Russia, except for Moscow.

4G/LTE800 frequencies:

Based on the results of the SCRF competition dated July 12, 2012:
DownLink / UpLink (MHz)
TELE2: 791-798.5 / 832 - 839.5
MTS: 798.5-806 / 839.5 - 847.5
Megaphone: 806-813.5 / 847 - 854.5
Beeline: 813.5 - 821 / 854.5 - 862
This network is actively developing.

4G frequencies "other operators"

Frequencies 4G "Osnova Telecom" LTE TDD 2300-2340 MHz Frequencies 4G "Antares" LTE TDD 1900-1920 MHz - who are they and to whom they provide communication is unclear)

GSM frequency:

GSM is a 2nd generation communication. GSM frequencies: uplink 890-915MHz, downlink 935-960MHz.

Frequency CDMA450(SkyLink):

Skylink operates on CDMA 450 and W-CDMA (UMTS) is operated by Big Three operators. Slylink CDMA frequency - uplink 453-457.5 MHz and downlink 463-467.5 MHz. W-CDMA (UMTS) - Uplink 1920 - 1980 MHz and Downlink 2110 - 2170 MHz.

UMTS frequencies:

UMTS (English Universal Mobile Telecommunications System - a universal mobile telecommunication system). Strictly speaking, this is 3G. UMTS frequencies: Uplink 1920 - 1980 MHz and Downlink 2110 - 2170 MHz.

Repeater frequencies:

If you need only voice communication, then choose GSM repeaters with frequencies of 900 MHz or DCS 1800 MHz. If you also need the Internet, then the frequency of the repeater must match the frequencies of 3G / UMTS.

GSM frequency range:

GSM 900: uplink 890-915 MHz, downlink 935-960 MHz. There is an additional GSM frequency range, the so-called E-GSM - this is an additional 10 MHz. E-GSM: uplink 880-890MHz, downlink 925-935MHz.

GSM frequencies in Russia:

GSM 900: uplink 890-915 MHz, downlink 935-960 MHz. Total 124 channels in GSM900. In each region of Russia, GSM frequencies are distributed among cellular operators individually.

3G MTS frequency:

Uplink 1950 - 1965 MHz and Downlink 2140 - 2155 MHz. MTS, like other cellular operators in the 3G range, has a width of 15 MHz.

3G modem frequencies:

As a rule, all 3G modems operate on 3G / UMTS frequencies: Uplink 1920 - 1980 MHz and Downlink 2110 - 2170 MHz., And support 2G network frequencies, that is, GSM900: uplink 890-915 MHz, downlink 935-960 MHz and DCS 1800 (aka GSM1800) Uplink 1710-1785 MHz and Downlink 1805-1880 MHz.

3G frequency range:

3G - in Russia it is CDMA450 (Skylink) and UMTS 2100. UMTS frequency range: Uplink 1920 - 1980 MHz and Downlink 2110 - 2170 MHz, a CDMA450 - uplink 453-457.5 MHz and downlink 463-467.5 MHz

Skylink frequency:

The existing CDMA450 network is uplink 453-457.5 MHz and downlink 463-467.5 MHz. In September 2010, Skylink received a license for 2100 frequencies, namely 1920 - 1935 MHz and Downlink 2110 - 2125 MHz.

GSM 1800 frequencies:

The GSM 1800 standard is more correctly called DCS1800. Its frequencies are Uplink 1710-1785 MHz and Downlink 1805-1880 MHz.

What frequency does 3G work on:

3G operates on UMTS frequencies - Uplink 1920 - 1980 MHz and Downlink 2110 - 2170 MHz. For example, the mobile operator Beeline in the Moscow region is testing its 3G in the GSM900 frequency band.

3G frequencies in Russia:

3G frequencies for all regions of Russia are the same: Uplink 1920 - 1980 MHz and Downlink 2110 - 2170 MHz.

3G megaphone frequency:

Megaphone in the 3G / UMTS range operates at frequencies: Uplink 1935 - 1950 MHz and Downlink 2125 - 2140 MHz.

DownLink - communication channel from the base station to the subscriber
UpLink is a communication channel from the subscriber to the operator's base station.

Standard 4G/LTE Frequency 2500

This type of communication is developing relatively recently and mainly in cities.

FDD (Frequency Division Duplex) - DownLink and UpLink operate on different frequency bands.
TDD (Time division duplex - time division of channels) - DownLink and UpLink operate on the same frequency band.

Yota: FDD DownLink 2620-2650 MHz, UpLink 2500-2530 MHz
Megaphone: FDD DownLink 2650-2660 MHz, UpLink 2530-2540 MHz
Megafon: TDD 2575-2595 MHz - this frequency band is allocated only in the Moscow region.
MTS: FDD DownLink 2660-2670 MHz, UpLink 2540-2550 MHz
MTS: TDD 2595-2615 MHz - this frequency band is allocated only in the Moscow region.
Beeline: FDD DownLink 2670-2680 MHz, UpLink 2550-2560 MHz
Rostelecom: FDD DownLink 2680-2690 MHz, UpLink 2560-2570 MHz
After the purchase of Yota by Megafon, Yota virtually began to work as Megafon.

Standard 4G/LTE Frequency 800

The network was launched into commercial operation at the beginning of 2014, mainly outside the city, in rural areas.

UpLink / DownLink (MHz)

Rostelecom: 791-798.5 / 832 - 839.5
MTS: 798.5-806 / 839.5 - 847.5
Megaphone: 806-813.5 / 847 - 854.5
Beeline: 813.5 - 821 / 854.5 - 862

Standard 3G/UMTS Frequency 2000

3G/UMTS2000 is the most widespread cellular communication standard in Europe and is mainly used for data transmission.

UpLink / DownLink (MHz)

Skylink: 1920-1935 / 2110 - 2125 - in the end, these frequencies are most likely to go to Rostelecom. The network is currently not in use.
Megaphone: 1935-1950 / 2125 - 2140
MTS: 1950-1965 / 2140 - 2155
Beeline: 1965 - 1980 / 2155 - 2170

Standard 2G/DCS Frequency 1800

DCS1800 - the same GSM, only in a different frequency range, mainly used in cities. But, for example, there are regions where the TELE2 operator operates only in the 1800 MHz band.

UpLink 1710-1785 MHz and Downlink 1805-1880 MHz

It doesn't make much sense to show division by operators, because in each region, the distribution of frequencies is individual.

Standard 2G/DCS Frequency 900

GSM900 is the most common communication standard in Russia today and is considered a second generation communication.

There are 124 channels in GSM900 MHz. In all regions of the Russian Federation, GSM frequency bands are distributed between operators individually. And there is E-GSM exists as an additional GSM frequency band. It is shifted in frequency relative to the base one by 10 MHz.

UpLink 890-915MHz and Downlink 935-960MHz

UpLink 880-890MHz and Downlink 925-935MHz

Standard 3G Frequency 900

Due to the lack of channels on the 2000 frequency, frequencies of 900 MHz were allocated for 3G. Actively used in the region.

CDMA Standard Frequency 450

CDMA450 - in the central part of Russia, this standard is used only by the SkyLink operator (Skylink).

UpLink 453 - 457.5 MHz and DownLink 463 - 467.5 MHz.

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

Cellular communication of the first generation was analog and is not used now, so we will not consider it. The second generation is digital and this feature has completely replaced 1G networks. The digital signal is more robust than the analog signal, which is a major advantage in mobile radio communications. In addition, a digital signal, in addition to speech, allows you to transmit data (SMS, GPRS). It should be noted that this trend towards the transition from an analog signal to a digital signal is typical not only for cellular communications.

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

GSM provides support for the following services:

GPRS data transmission
Speech transmission
Sending short messages SMS
Fax transmission

In addition, there are additional services:

Number identification
Call forwarding
Call waiting and hold
conference call
Voice mail

GSM network architecture

Let us consider in more detail 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. The SS performs the functions of call handling and connection establishment, and is also responsible for the implementation of all assigned services to the subscriber. The BSS is responsible for the functions related to the radio interface.

SS includes:

MSC (Mobile Switching Center) - GSM network switching center
GMSC (Gate MSC) - a switch that handles 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)

BSS includes:

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

The composition of the switching subsystem SS

The MSC performs the 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 charging the communication services provided by the network, accumulates data on conversations that have taken place and transfers them to the settlement center (billing center). The MSC also compiles the statistics needed to monitor and optimize the network. The MSC not only participates in call control, but also manages the location registration and handover 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 of the subscriber's registration (conclusion of the service contract by the subscriber) and is stored until the subscriber terminates the contract and is removed from the HLR register.
The information stored in the HLR includes:

Identifiers (numbers) of the subscriber.
Additional services assigned to the subscriber
Information about the location of the subscriber, accurate to the MSC / VLR number
Subscriber authentication information (triples)

The HLR can be implemented as a built-in function in the MSC/VLR or standalone. If the capacity of the HLR is exhausted, then an additional HLR may 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 of 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. Service information is temporarily stored in the VLR, and due to this, the associated MSC can serve all subscribers located in the service area of this MSC. The HLR and VLR store very similar subscriber information, but there are some differences that will be discussed in later chapters. When a subscriber moves into the service area of a new MSC, the VLR connected to that MSC requests information about the subscriber from the HLR that stores that subscriber's data. The HLR sends a copy of the information to the VLR and updates the location information of the subscriber. After the information is updated, the MS can make outgoing/incoming connections.

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

The composition of the subsystem of base stations BSS

The BSC manages 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 collection. Each MSC can manage multiple BSCs.

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

Geographical construction of GSM networks

Each telephone network needs a specific structure to route calls to the desired exchange and on to the subscriber. In a mobile communication 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.

Although the cell is the basic unit of the GSM communication system, it is very difficult to give a clear definition. It is impossible to attach this term to an antenna or to a base station, because there are various cells. However, a cell is a certain geographical area 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 its own unique number, called the Global Cell 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 a mobile station call will be made. The location of the subscriber within the network is associated with the LA in which the subscriber is currently located. The given zone identifier (LAI) is stored in the VLR. When an MS crosses the border between two cells belonging to different LAs, it sends information about the new LA to the network. This only happens if the MS is in Idle mode. Information about the new location is not transmitted during the established connection, this process will occur after the end of the connection. If an MS crosses a boundary between cells within the same LA, it does not inform the network of its new location. When an incoming call arrives at an MS, the paging message is distributed within all cells belonging to the same LA.

The MSC service area consists of a number of LAs and represents the geographic portion of the network that is under the control of a single MSC. In order to route a call to an MS, the service area information of the MSC is also needed, so the service area is also tracked and recorded in the database (HLR).

The PLMN service area is a set of cells served by one operator and is defined as the area in which the operator provides the subscriber with radio coverage and access to its network. There can be multiple PLMNs in any country, one for each operator. The definition of roaming is used when an MS moves from one PLMN service area to another. The so-called intra-network roaming is a change of MSC/VLR.

The GSM service area is the entire geographic area in which a subscriber can access the GSM network. The GSM service area is expanding as new operators sign contracts to work together to serve subscribers. Currently, the GSM service area covers, with some gaps, many countries from Ireland to Australia and from South Africa to America.

International roaming is the term used when an MS moves from one national PLMN to another national PLMN.

GSM frequency plan

GSM includes several frequency bands, the most common are: 900, 1800, 1900 MHz. Initially, the 900 MHz band was allocated to the GSM standard. Currently, this range remains worldwide. In some countries, extended frequency bands are used to provide greater network capacity. The extended 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, in order to increase competition between operators, the UK began to develop a new version of GSM, which is adapted to the 1800 frequency band. Immediately after the approval of this band, several countries applied for the use of this frequency band. The introduction of this range has increased the growth in the number of operators, leading to increased competition and, accordingly, an improvement in 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 bands: GSM 1710-1805/1785-1880 MHz. Until 1997, the 1800 standard was called Digital Cellular System (DCS) 1800 MHz, currently it is called GSM 1800.

In 1995, the PCS (Personal Cellular System) concept was specified in the USA. The main idea of this concept is the possibility of providing a personal connection, that is, a connection between two subscribers, and not between two mobile stations. The PCS does not require these services to be based on cellular technology, but this technology is currently recognized as the most efficient for this concept. The frequencies available for PCS implementation are in the 1900 MHz region. Since the GSM 900 standard cannot be used in North America due to the fact that this frequency band is occupied by another standard, the GSM 1900 standard is an opportunity 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 USA. 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 on national networks, providing operators with additional capacity.

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The development of a new pan-European digital cellular standard began in 1985. Especially for this purpose, a special group was created - Group Special Mobile. The abbreviation GSM gave the name to the new standard. Later, GSM, due to its wide distribution, began to be deciphered as Global System for Mobile Communications. To date, the GSM system has evolved into a second-generation global standard, which occupies a leading position in the world both in terms of coverage area and in terms of the number of subscribers.

The GSM standard provides for the operation of transmitters in two frequency bands. The frequency band 890-915 MHz is used to transmit messages from the mobile station to the base station, and the band 935-960 MHz is used to transmit messages from the base station to the subscriber. The frequency spacing between adjacent communication channels is 200 kHz, thus, 124 communication channels are placed in the band allocated for reception / transmission. This standard uses multiple access with time division channels (Time Division Multiple Access, TDMA), which allows one carrier frequency to place eight voice channels simultaneously. A speech codec with regular pulse excitation and a speech conversion rate of 13 Kbps is used as a speech converting device. Block and interleaved convolutional coding is used to protect against errors that occur in radio channels. An increase in the efficiency of coding and interleaving at a low speed of movement of mobile frequencies is achieved by slowly switching operating frequencies during a communication session (at a speed of 217 hops per minute).

With regard to services, here the developers of the standard sought to ensure interoperability of networks from the very beginning. GSM and ISDN (Integrated Service Digital Network) for the range of services offered. In addition to the usual telephone connection, a GSM user is provided with a variety of data transfer services. GSM subscribers can exchange information with subscribers of ISDN, conventional telephone networks, packet-switched networks and circuit-switched networks using various access methods and protocols, such as X.25. Fax transmission is possible using the appropriate fax machine adapter. A unique feature of GSM, which was not available in older analog systems, is the bidirectional transmission of short messages SMS (Short Message Service) - up to 160 bytes, transmitted in a store-and-forward mode.

In the "figure" it was possible to implement additional features that are not available in the analog standards of the previous generation. This mainly applies to the sound quality of the interlocutor's voice (quality of transmission and speech coding), subscriber authentication and automatic roaming. And besides, it's:

use of SIM-cards to provide access to the channel and communication services;
encryption of transmitted messages;
radio interface closed from listening;
subscriber authentication and identification of subscriber equipment by cryptographic algorithms;
use of short message services transmitted over signaling channels;
automatic roaming of subscribers of various GSM networks on a national and international scale;
internet roaming of GSM subscribers with subscribers of DCS1800, PCS1900, DECT networks, as well as with Globalstar satellite personal radio communication system.

Today, the GSM standard is actively developing, and already now the user can be provided with a high-speed packet data transmission (GPRS) service or access to the Internet.

TDMA/IS-136 (D-AMPS)

The TDMA/IS-136 specification was defined in 1998 in the United States by the Telecommunications Industry Associations (TIA) in order to digitize the AMPS (Advanced Mobile Phone Service) analog standard, which is widespread in America. For AMPS compatibility, the TDMA/IS-136 specification uses a 30 kHz carrier bandwidth with three slots. Unlike frequency division systems, all subscribers of a TDMA system operate in the same frequency band, but each has time access restrictions. Each subscriber is allocated a time period (slot) during which he is allowed to "broadcast". After one subscriber completes the broadcast, the permission is passed to the next, and so on.

Today, IS-136 can by no means be considered a dead-end branch of the development of cellular communications (another question is how the fate of this standard will develop in our country). Just like in GSM, this standard provides for successive steps towards the transition to a third generation system: GPRS, EDGE, etc.

PDC

As in many other cases, Japan had its own way of development. The Land of the Rising Sun uses the PDC (Personal Digital Cellular) standard. The standard is based on a three-slot TDMA solution. The carrier width is 25 kHz.

Despite the fact that PDC networks are located only in Japan, this standard (as of the end of 1999) confidently occupies the second position after GSM in the popularity rating among digital standards by number of subscribers. And this is not surprising: in early 2000, the number of cellular subscribers in Japan exceeded the number of subscribers to standard wired telephony. By the way, it is in Japan that test sections of third-generation networks are already operating - despite the rapid pace of development of cellular communication systems, the Japanese are more than a year ahead of everyone else.

CDMA/ IS-95

CDMA (Code Division Multiple Access), or cdmaOne, is an all-digital standard that uses the 824-849 MHz frequency range for reception and 874-899 MHz for transmission. In fact, the "new" standard was developed back in the 30s. And then for decades it was used exclusively in military communication systems, both in the former USSR and in the USA. The military paid attention to this standard for a reason, as it has many features that are useful for such systems, the main of which is the secrecy of communications. The fact is that the principle of operation of CDMA is to “smear” the spectrum of the original information signal by modulating it with a noise-like signal that occupies a much wider frequency range than the original signal. The shape of this noise signal is a unique code for each subscriber, which makes it possible to identify it in a CDMA receiver. At the CDMA base station, the common signal received from many users is again modulated with a similar noise-like signal - as a result, the original signal is restored.

There are numerous advantages to this seemingly simple scheme of work. Firstly, all subscribers of the CDMA system operate in the same frequency band (the width of this band is 1.25 MHz), without interfering with each other, since the number of variants of modulating noise-like signals is several billion.

Secondly, high noise immunity, both from passive and active interference. Due to the fact that a broadband signal “swallows” narrowband interference without changing its shape, a high quality of voice and data transmission is provided (comparable to high-quality wired lines). This, by the way, allows you to work with a much lower transmitted signal power, that is, CDMA networks are more environmentally friendly. Less operating power also ensures longer operation of subscriber devices without recharging batteries.

As for global trends in the development of this standard, they are more than extensive. The main one is: in the radiotelephone systems of the following, third generation various variants of CDMA technology with even larger carrier channel widths will be used.