Yuri Andreevich Gromakov was born on 20 December 1946

Yuri Andreevich Gromakov was born on 20 December 1946.

In 1971, he graduated from the Faculty of Aircraft Radioelectronics of the Moscow Aviation Institute (a technical university).

Until 1994, he worked in various enterprises of the military-industrial complex. From 1992 to 1994, he was the chief designer of mobile radio systems with a major scientific and technical association. From 1994 to the present, he has been a Vice-President for Development with Mobile TeleSystems OJSC, and since 2007 he has been the Director-General of the R&D centre OJSC Intellect Telecom. He is a Doctor of Technical Sciences and a professor, and has over 100 publications, 22 industrial patents and three monographs to his name.

His scientific achievements include his work on the creation of convergent telecommunication networks. He proposed a new means, patented in Russia and the United States, of cellular communication based on the merging of cellular network resources with a satellite positioning system, and developed a new topology for cellular communication systems using repeaters with capacity transfer, thereby reducing the capital and operational expenditure on the creation of a cellular communication radio system by up to one half. He developed and patented a system for locating moving objects with an accuracy to within 3 cm which has been brought into commercial use in Moscow and St Petersburg. In recent years, he has been conducting research in connection with the development of cognitive radio, and on the basis of those principles has developed a means of GSM data transfer at a rate exceeding ten megabytes per second.

Yuri Gromakov is a renowned expert in the field of mobile radio systems, satellite navigation and telematics, having received recognition both in Russia and internationally. His scientific contribution to the development of mobile communication networks in Russia has involved the development and implementation of a strategy and principles for the deployment of mobile communication and data transfer networks, and the theoretical justification and experimental validation of solutions for the electromagnetic compatibility of radio facilities used in aeronautical radionavigation and aircraft landing systems with GSM 900 cellular communication system equipment. He has led and personally participated in work on resolving the scientific and technical issues associated with the introduction and development of GSM, UMTS, WiMax and other mobile communication systems, on the development of a master plan for the development of GSM networks in Russia, on the organization of national GSM roaming, and on the creation of integrated schemes for terrestrial mobile, satellite and fixed communications.

By a Decree of the Government of the Russian Federation, Yuri Gromakov was awarded the 2003 Prize of the Government of the Russian Federation for his work on the development and creation of new technologies. He is an Honorary Radio Operator of the Russian Federation, an Academician of the International Academy of Communications and Vice-President of the National Radio Association.

/TT/FILE_CONVERT/54BC7D744A795954278B468D/DOCUMENT.DOC 03.10.09

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Y.A. GromakovDoctor of Technical Sciences,Professor, General DirectorOJSC Intellect Telecom R&D centre

A new method for cellular communications

The lead player on the telecommunication stage is now cellular communication. Ever since it first came onto the scene, the conception and three principles of cellular system construction have remained unchanged:

• frequency (code) re-use within cells;

• call continuity thanks to the cell-to-cell handover of the mobile subscriber;

• location of the mobile subscriber by the cellular system.

It is by combining these three principles (Figure 1) that a cellular system and its services are created. The concept of cellular communication based on frequency re-use to achieve a manifold increase in the capacity of mobile communication networks was put forward in the 1940s by AT&T, which in 1968 submitted a report to the United States Federal Communications Commission (FCC) on future cellular communication systems.

None of the aforementioned principles have thus far been changed. All the generations of cellular communication, from the first (1G) to the third (3G), and even the next generations (LTE and IMT-Advanced) are based on these three principles.


+ Communication

services

Cellular communication

system

Frequency

re-use

Handover

Mobile

station

location

Figure 1

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For many years, the cellular topology, initially geared to the transmission of voice calls, fully satisfied the interests of users and operators. Then came increasing market demand for higher rates of data transfer, which could be met by expanding the bandwidth of communication channels, made possible with the use of higher carrier frequencies for cellular communication. It was just at this time that the emerging new generations of cellular systems came up against the physical constraints associated with the implementation of radio interfaces, and against the shortcomings of a cellular topology.

Physical constraints with cellular communication

The capabilities of the radio interface in a cellular system are limited by a number of factors. These include:

• physical limitations in terms of radio wave propagation distance, and the considerable drop in communication range as the operating frequency increases (Table 1, Figure 2);

• the negative influence of multipathing when radio waves are propagated in an urban environment, becoming more pronounced as the frequency increases;

• intersymbol interference in the channel during data transmission;

• increasing negative influence of atmospheric precipitation as the frequency increases;

increasing influence of the Doppler effect with call transmission at higher frequencies;

• real presence of external noise, presence of intrasystem interference, etc.

Frequency

MHz

Cell radius (km)

Cellarea(km²)

Area ratio (450)

Area ratio (950)

450 50 7850 1.0 0.3

850 30 2826 2.8 0.8

950 27 2289 3.4 1.0

1800 14 615 12.8 3.7

1900 13.3 555 14.2 4.1

2100 12 452 17.4 5.1

The aforementioned physical constraints are an objective reality, are essentially insurmountable and circumscribe the capabilities of cellular communication. It is for this reason that frequencies higher than 10 GHz remain virtually unused for mobile communications. The use of OFDM and MIMO technologies in WiMAX and LTE goes some way towards reducing the negative influence of multipath radio wave propagation.

Shortcomings of cellular topology

As things stand, a cellular network topology (Figure 1) is unquestionably the most effective means of implementing public mobile communication systems. However, as time goes on its shortcomings are also becoming ever more apparent:


IMT-2000

GSM-1800

GSM-900

CDMA450

Figure 2Table 1

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• the size of cells diminishes with the use of higher frequencies owing to physical limitations on the radio wave propagation distance, necessitating a higher number of base stations, controllers and connection circuits;

• smaller cell dimensions necessitate a higher number of handovers as the mobile station moves around, reducing the likelihood of successful call termination;

• there is an increase in network resource costs associated with the management of connection, handover, signalling and synchronization processes as the subscriber moves around an area with small cell dimensions.

Today’s mobile subscribers are not interested in communication standards, their demands having first and foremost to do with the nature and quality of the available services, their accessibility in terms of time and location, ease and speed of access to the services, and, of course, their cost. However, one has to agree that a subscriber's "consumer portfolio" stems from the capabilities of specific mobile communication technologies. And efforts are currently being made to expand those capabilities, essentially by means of new types of radio interface and by moving from circuit switching to packet switching, while not, however, addressing the most fundamental question, namely that of the principles underpinning the construction and topology of cellular networks.

How does one set about changing the topology of cellular communication in the interests of enhancing its effectiveness for subscribers and operators? What will bring about a change in cellular communication?

Developing the principles of cellular communication

Let us consider the changes that might occur in cellular communication, the way in which it operates and its topology, if we were to change one of its three underlying principles (Figure 1) – for example, the principle of mobile subscriber location.

As things stand, locating a mobile subscriber is effected by the cellular communication system's own resources. Let us imagine the function of locating the mobile subscriber being transferred from the cellular network to the mobile station. The cellular network management system no longer has to concern itself with the task of locating a multitude of active subscribers, either moving around or stationary at any given moment, and located either within their own network or in the catchment area of other networks. Using data obtained from a satellite global positioning system (GPS, GLONASS, etc.), each mobile station determines its own coordinates and transmits them to the management system via the cellular communication channels. On the basis of the location data supplied by the mobile station, the network is able to connect the subscriber to other mobile stations or to subscribers in the fixed telephone network (PSTN). The principles for construction of a cellular communication system with transference of the subscriber location functions from the network to the mobile station are shown in Figure 3.

Locating mobile subscribers with the accuracy inherent in a satellite global positioning system makes for simplification of the cellular communication system infrastructure, resulting in resource savings, reduced expenditure on network construction and a considerable expansion of functional capabilities by comparison with the current situation.


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Given, moreover, that the new generations of cellular communication, as well as existing 2.5G and IMT-2000 systems, are moving towards the widespread introduction of new types of service involving subscriber location, the use of GPS/GLONASS data will help to broaden the range of services on offer.

Such services include, for example, navigation services, emergency assistance, tourist information, tracking the location of goods in transit, and so on. Their implementation is made possible by increasing the accuracy with which the mobile station is located by the cellular communication network, this being achieved in the case, for example, of GSM or UMTS, by further increasing the complexity of the cellular communication system and increased expenditure on the hardware and software resources necessitated by the incorporation of new elements, namely type A location measurement units (LMUs), connected via the radio interface to the base stations, or type B LMUs, connected to the base station controller via the cellular A-bis interface, as well as mobile location centres (MLC). One of these, the serving MLC (SMLC), handles positioning requests, final calculation of the coordinates and accuracy of the result obtained, while the other, the gateway MLC (GMLC), performs client support functions (Figure 4).


Frequency

re-use

Mobile

station

location

+

Cellular

ommunication

system

HandoverCommunication

services

Satellite global positioning systems

(GPS, GLONASS, etc.)

Figure 3

- 6 -

The best-known methods for locating a mobile station on the basis of cellular network data are: Cell ID, for which there is no need to determine the signal strength or delay; Cell ID-TA (timing advance); TOA (time of arrival); and E-OTD (enhanced observed time difference).

In short, implementation of the above methods of mobile station location, based on the cellular network’s own resources, calls not only for the installation of additional hardware and software resources, but also for the assignment of additional connection circuits.

All of this results in continued inefficient exploitation of the cellular network's own resources and additional expenditure by operators on hardware and software to handle mobile station location by the network, while the location accuracy is limited to "within the cell”, which can range from a few hundred meters to tens of kilometres.

As a result of research done to determine the feasibility of implementing principles of cellular communication system construction based on a transfer of the location function from the network to the mobile station, with use of the GPS/GLONASS systems, as an integral part of the cellular network infrastructure, a new method of cellular communication, patented in Russia and the United States, is proposed.

Use of this innovative approach will serve to enhance the efficiency of the cellular communication system by increasing its traffic-handling capacity, reduce the burden on the cellular interfaces used for the transmission of service information (for example, between the mobile station and BTS, BTS and BSC, and BSC and MSC) and free up network resources for payload transmission, with, at the


MSC

VLR MSC

VLR

OMC

HLR

BSC

ISDN

PSTN

MSC/VLR service area

Location Area

MS GSM

BTS

Location

system

LMU

LMU

SMLC GMLC

MSC

VLR

External clients of the location system

Figure 4

GSM network PLMN service area

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same time, a reduction in the volume of cellular communication system hardware and software resources used for the location of mobile stations (LMUs, SMLCs, GMLCs, etc.) while achieving greater location accuracy (Figure 5).

A further benefit lies in expansion of the system's functional capabilities through the creation of cells located at different heights above the Earth’s surface (for example, on different floors of buildings), as well as in the implementation of vertical handover, the organization of corporate networks for groups of mobile subscribers within cells, the use of mobile station location data for forming the maximum of base station multiple-beam antenna radiation patterns in the direction of a mobile station.

In essence, increasing the efficiency of cellular communication can be achieved by excluding from the cellular communication method (Figures 1 and 2) the location function that is performed by the cellular network, and by implementing a cellular communication system incorporating the use of GPS/GLONASS (or other) resources to handle the location functions within the cellular network, as well as handover and frequency (code) re-use.

Functioning of the combined cellular communication and satellite positioning system

The communication coverage area is calculated on the basis of a digital ground map, including features such as building heights and dimensions and road layouts, and a radio wave propagation model for a range of building conditions and with respect to a given frequency range and allotted frequency resource. Also taken into account are the predicted channel loadings, communication reliability and quality requirements, antenna directional characteristics, electromagnetic compatibility conditions vis-à-vis other radio facilities, handover requirements, and so on. The calculation results are then used to determine the coordinates, height and parameters of the communication system base stations.


MSC

VLR MSC

VLR

OMC

HLR

BSC

ISDN

PSTN

MSC/VLR service area

PLMN service area

Location area

MS+GPS

BTS+GPS

MSC

VLR

GPS/GLONASS satellites

Figure 5

GSM network

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The cell configuration for each BTS is formed, recorded in electronic form and stored in the cellular system management centre, from where the data are transmitted and recorded in the BSC controllers as required for management of the corresponding BTSs. These data, together with the boundary coordinates, working frequencies (codes) and communication parameters of the neighbouring cells are used to create a digital ground map in the form of electronic fragments. The management centre can be set up in the same way as the management centres of existing cellular communication systems, but equipped with the necessary software for performing all the operations associated with the communication functions in question.

The mobile station must include the cellular communication terminal, a satellite global positioning system receiver and a controller for storage and processing of the geographic map data. As it receives and processes signals from the satellites, it periodically determines its own spatial, including geographic, coordinates, with the periodicity of that task being adapted (tied) to the speed at which the mobile subscriber is moving. If the results of two consecutive determinations of the mobile station’s own coordinates vary considerably, meaning that the mobile subscriber is travelling at high speed, the interval between determinations will be reduced in order to increase the location accuracy.

When a mobile station first enters the cell of a given base station, the latter sends it a fragment of the digital electronic map requested from the cellular system management centre. The map shows the boundary coordinates of the cell in question and those of its neighbours, together with the working frequencies and codes of the base stations and the communication parameters, with the size of the digital map fragment being tailored to the speed of travel of the mobile subscriber.

The mobile station periodically compares the positioning data received from the GPS or GLONASS system with the digital electronic map fragment in order to check with which base station it is associated. When it moves into a new cell, the mobile station switches to the working frequency or code, and to the communication parameters, of the base station for the cell in which it is now located.

The positioning data sent by mobile stations to base stations enable communication to be established with the mobile stations by means of multipath intelligent antennas. The maximum of the radiation pattern of one of the antenna beams is lined up directly with the coordinates of the mobile station and, on the basis of its positioning data, is used to track the movement of that station (Figure 6).

The use of precision coordinates for mobile station positioning within the intelligent antenna management system does away with the need for smooth antenna radiation pattern adaptation modes on the subscriber side and enables use of a beam switching mode with a fixed "needle-point" pattern which makes for a shorter call set-up time. The use of switched-beam antennas increases the communication distance between the mobile station and base station, this being equivalent to increasing the dimensions of the cell.

Within a single cell (with operation on a single group of frequencies or codes), it is possible to form microcells with given boundaries determined by geographic coordinates, within which mobile subscribers can make use of communication parameters – type of radio interface, transmission speed, communication protocol, tariff, and so on – that are different to those of the cell. Thus, for example, when a mobile subscriber is located within a microcell, he or she can benefit from various facilities or additional services.


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Determining the location of mobile stations by means of a satellite global positioning system ensures roaming when a mobile station moves from one communication network into another using either the same communication standard or different communication standards and types of radiocommunication. In this case, the coordinates of the boundary cell will correspond to those of the boundaries of the communication networks in question (particularly where national boundaries are concerned). A mobile subscriber crossing a national border, or from one cellular communication area into another, obtains roaming services immediately upon crossing the boundary of the communication area, unlike what happens with existing cellular networks, where the communication area and cell boundaries depend on the local radio wave propagation conditions and cannot in principle be precisely aligned with the network or national boundaries.

Furthermore, by using digital electronic maps and mobile station positioning data obtained from satellite global positioning systems, with account taken of buildings, BTS system antenna siting conditions and radio wave propagation models, it is possible to regulate the power level of mobile and base station transmitters based on the distance between them. According to the load generated by the mobile stations within a cell, the dimensions and configuration of cells, as well as the handover conditions, can be remotely set for each mobile station from the cellular system management centre.

The high level of positioning accuracy provided by global satellite positioning system data enables the cellular system to set priorities for access to communication services, impose limitations or bar any given mobile station from accessing the network. The proposed method for cellular communication also enables pinpoint or area-based charging (freely configurable by means of pre-established coordinates) for the communication services on offer to subscribers.

The current positioning data that the mobile subscriber can access worldwide are used for selecting the desired operator's mobile network and also the types of service required within that network, based on the settings recorded in the mobile station by the subscriber or operator, with reference, as the case may be, to the communication service tariffs in force.


RR11

RR22

φφ=f(x,y)=f(x,y)

xx11yy11

xx22yy22

Digital mapDigital map

GPS/GLONASS

WiFi

micro

Figure 6

XX11VV11

XX22VV22

RR22

RR11

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Thus, the new method for cellular communication enhances the effectiveness of cellular communication systems by incorporating data from satellite global positioning systems into the network.

Migration to the new cellular network topology can be implemented gradually through the staged modification of existing networks.

Precision positioning system

One of the first practical steps towards realization of the new method for cellular communication was the creation of a system for the precise positioning of mobile objects (Figure 7).

This includes the GPS/GLONASS reference stations, which are used in determining the differential corrections to the coordinate values measured by the GPS/GLONASS receivers in the subscriber terminals. The differential corrections are calculated as the variation between the coordinates of a given base station measured at a given point in time (x1, y1) and the actual coordinates of the base stations (х0, у0) determined by means of precise geodesic methods.

The measured values of an object’s coordinates (x1, y1) contain errors caused by the changing radio wave propagation conditions between the GPS/GLONASS satellites and the terrestrial receiver. The value of the differential corrections Δx = (x1 — x0) and Δy = (y1 — y0) remains virtually constant within a radius of 30 to 40 km from the reference station. Any subscriber (i.e. user of precision coordinates) located within this area can obtain differential correction values from the computation centre via the cellular network.

In the course of researching the feasibility of practical implementation of the proposed method for cellular communication in conjunction with a precision positioning system, the following results were obtained:


BTS GSM

GPS/GLONASS

receiver

30-40

км

GSM network

Reference station

precision coordinate database

Precision coordinate

users

Х1 Y1

Computing centre

Х0 Y0

ΔХ1

ΔY1

GPS/GLONASS

reference station

Satellites in the GPS/GLONASS navigation systems

Figure 7

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• principles were identified for the staged migration of GSM and UMTS cellular networks to the new cellular communication infrastructure, including combined operating modes and the use of GSM/GPS and UMTS/GPS terminals with subsequent transition to GPS/GLONASS equipment;

• solutions were found to the problems associated with mobile station positioning in buildings, based on inertial navigation methods using MEMS technology;

• a GPS/GLONASS differential satellite navigation system with a positioning accuracy of up to 3 cm in real time and geared towards use in conjunction with the proposed cellular communication system was developed and brought into commercial operation in Moscow and St Petersburg;

• 3D digital maps and new RF planning methods were developed for the new system combining cellular communication and differential satellite navigation.

The proposed method for cellular communication is the fruit of research carried out by the Intellect Telecom R&D centre and the major Russian GSM/UMTS cellular communication operator Mobile Telesystems.

List of abbreviations

MS - Mobile Station

BTS - Base Transceiver Station

BSC - Base Station Controller

MSC - Mobile Switching Centre

VLR - Visitor Location Register

HLR - Home Location Register

OMC - Operation and Maintenance Centre

PSTN - Public Switched Telephone Network

PLMN - Public Land Mobile Network

LMU - Location Measurement Unit

SMLC - Serving Mobile Location Centre

GMLC - Gateway Mobile Location Centre

ToA - Time of Arrival

E-OTD - Enhanced Observed Time Difference

OTDoA - Observed Time Difference of Arrival


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Bibliography

1) ITU-R: Framework and overall objectives of the future development of IMT-2000 and systems beyond IMT-2000. Recommendation ITU-R M. 1645, June 2003.

2) Gromakov Y.А. Стандарты и системы мобильной радиосвязи (Mobile radio standards and systems – in Russian) — М.: EcoTrends, 2000. 239 pp.

3) Gromakov Y.А., Severin А.V., Shevtsov V.А. Технологии определения местоположения в GSM и UMTS (Positioning technologies in GSM and UMTS – in Russian) — М: EcoTrends, 2005. 144 pp.

4) Patent No. 2227373 (Russia) 20.04.2004. Способ сотовой связи (Method for cellular communications), Y.А. Gromakov, V.A. Shevtsov

5) Patent No. US 7, 228, 135 B2 (USA) 05.06.2007. Method for Cellular Communications, Y.A. Gromakov, V.A. Shevtsov.

6) Global Positioning Systems, Inertial Navigation, and Integration. Second edition. Mohinder S. Grewal, Lawrence R. Weill, Angus P. Andrews. By John Wiley & Sons, Inc., 2007, 525 pp.


Yuri Andreevich Gromakov was born on 20 December 1946

Business

mobile communication

cellular topology

field of mobile radio

development of gsm networks

development of cognitive

mobile subscriber location

mobile telesystems ojsc

data transfer networks