RU2248098C2 - Method for building cellular radiotelephone communication - Google Patents

Abstract

FIELD: radio engineering.

SUBSTANCE: method involves arranging base stations supplying services to objects belonging to given region in pentagon vertices. Its two non-adjacent angles are equal to 90° and vertex with an angle of 132° is between them. The other angles are equal to 114°. Communication zones cover territory under service without gaps. Their base stations have circular pattern and two radii of communication zones r and R related to each other as r=0.575R. The stations having lesser serviceability radius form a square which side is equal to 1.827l.

EFFECT: reduced service zone overlay degree; coverage of uneven and convex earth surface types.

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Description

The method of building a cellular communication network relates to radio communication systems and can be used to provide telecommunication services.

The organization of cellular communication systems is based on the division of the served territory into microzones - cells. See, for example, US patent No. 5418779 for class H 04 L 12/48 “Network architecture with high-speed switching”, the geometry of the base stations (small circles) and communication areas (large circles) of the known device are shown in figure 1.

Figure 1 shows that in the known cellular communication system, the service area is completely covered by cells, in the center of which are located base stations located at an equal distance from each other, forming regular triangles. In the service area, channel switching between radio zones is controlled so that when a moving object from one zone to another the radio exchange can continue without interruption. To do this, it is necessary to carry out overlapping zones. Full coverage of a flat surface using regular polygons is achieved only in three cases: for equilateral triangles, squares and hexagons. Conventionally, the geometry of an individual cell, taking into account the overlap, is taken as a regular hexagon, in the center of the circumscribed circle of which there is a base station. It is for the mentioned regular polygons optimal by the criterion of the minimum area of overlapping cells (21% of the height area, see A. Zykov’s book Fundamentals of Graph Theory. - M .: Nauka, 1987. 381 pp.), That the limit (minimum and maximum) estimates of the required number of communication channels corresponds to the chromatic number of the oriented Berge graph, characterizing the mutual influence of the electronic means serving these communication channels. The calculation is carried out using the oriented graph invariants: A is the maximum degree of vertices, α is the vertex independence number, χ is the chromatic number of the additional graph. In relation to the claimed cellular communication network, characterized by a significant number of base station sectors analyzed from the position of their influence, the maximum number of frequency channels M _max (the chromatic number of the cellular network graph) is estimated based on calculating the maximum degree of the vertices of the Berge graph Δ by the formula

The minimum required number of frequency channels M _{min is} limited by the “clique” K, numerically equal to the number of vertices of the maximum complete subgraph extracted from the Berge graph

M _min = K.

As a result of calculations using the above two formulas, estimates are obtained in the form of dependences of the minimum and maximum necessary frequency channels depending on the number of sectors of the base station, simultaneously involved in serving the common area in the interest of increasing the cellular network schedule.

Estimates obtained using the above formulas provide rough estimates, since they do not take into account the mutual influence of the base station sectors on adjacent frequency channels and through one frequency channel; additional restrictions on the use of frequency channels of the base station under the conditions of ensuring electromagnetic compatibility with other electronic devices operating in the field of energy availability for interference from base station transceivers. The listed factors bias the estimates obtained using the above formulas towards their maximization. The use of the above formulas shows that when the base stations are located at the vertices of equilateral pentagons, an increase in the number of channels in the sector area S _{sec is} achieved by about 1.5 times compared with the location of the base stations at the vertices of regular hexagons.

The closest in technical essence to the proposed solution is the method of constructing a cellular communication network described in the USSR author's certificate No. 1626412 A1 in class H 04 B 7/26 “Method of radio communication with mobile objects in a cellular structure communication system” adopted as a prototype.

The well-known architecture (geometry) of cellular communications (Fig. 1) consists of base stations located at the vertices of the triangles, and the base stations are controlled under the condition that during the transition of a moving object from one zone to another, telephone exchange could continue without interruption. Transmitter power control is based on measurements and commands of moving objects, i.e. according to the feedback scheme. For each direct traffic channel, the power is individually regulated. In the process of power control, base stations periodically reduce the radiation power in the traffic channel. The power is reduced until the moving object detects that the threshold level of the frequency of error frames is exceeded and a request is sent to increase the transmitter power of the base station. Receiving commands from moving objects, base stations increase the radiation power in the corresponding channels of the graph, while it redistributes the allocated to it by the system and strictly limited power resource.

To ensure the effectiveness of radio communications by expanding the service area while maintaining the number of base stations in the prototype, circular scanning is proposed using phased array antennas installed on base stations where signals from moving objects are received. The use of phased antenna arrays requires storing the azimuthal angle of the moving object relative to the base station and making connections with the moving object only during the intersection of the main lobe of the phased array antenna of the base station of the moving object. For the normal loading of the communication system requires a uniform distribution of moving objects along the azimuthal angle of the radiation pattern, which is difficult to ensure in real conditions, this is a significant drawback of the prototype method.

To eliminate these drawbacks in the proposed method for constructing cellular communications, which consists in continuing continuous radio communication during the transition of a mobile station from one service area to another, according to the invention, base stations of two radiuses of service areas are used, which are located at the vertices of identical equilateral pentagons with two non-adjacent right angles, covering the served territory without gaps, and base stations with a smaller service radius are located at the intersection center two mutually perpendicular lines passing through three base stations, forming a square.

The inventive method for constructing cellular communication is based on the solution of the problem of optimal placement on the earth's surface of base stations of a cellular network with a uniform (circular) communication zone, ensuring minimal mutual overlap of communication zones. Moreover, the communication zones overlap without a gap (without gaps between the communication zones), which ensures radio exchange without interruption. To do this, we use the following approach. The mutual overlap area γ will be determined by the analytical formula

where β is the adjacent angle of overlap shown in Fig.3.

The optimal solution from here is determined by the formula

cos2β = 2cosβ + sinβ, (2)

The real roots of equation (2) will be: β1 = -90 ° and β ₂ = 125.25. To provide coverage of a flat surface with equilateral pentagons without gaps, if two pentagon angles of 90 ° are selected, the remaining angles will be: 132 ° (between 90 ° angles) and two 114 ° angles. The side length of an equilateral pentagon is denoted by l. The vertices of the pentagon, located at the intersection of mutually perpendicular angles (90 °), form a square with side h = s = 1,827l (figure 2). At these peaks are base stations providing a radius of the communication zone of 0.4355l, and at peaks with angles of 114 ° and 132 ° transmitters with a radius of the communication zone of 0.7574l.

The optimality of the selected geometry is confirmed by calculations. For hexagonal cells (Fig. 1) and the proposed geometry (Fig. 2), we select fragments in the form of similar hexagons, shown by solid bold lines. The degree of overlap is defined as the ratio of the overlap area to the total area bounded by solid bold lines

- суммарная площадь зон перекрытия,

- площадь отдельной зоны перекрытия, S_общ - площадь шестиугольного фрагмента.Where

- total area of overlapping zones,

- the area of a separate overlapping zone, S _total - the area of the hexagonal fragment.

) на фиг.1 и фиг.2 показаны в виде областей наложения пересекающихся окружностей и показаны штриховкой. Общая площадь (S_общ) ограничена сплошной толстой линией и представляется в виде шестиугольных фрагментов (фиг.1 и фиг.2), похожих на усеченные ромбы.Overlapping zones (

) in figure 1 and figure 2 are shown in the form of overlapping areas of intersecting circles and are shown by hatching. The total area (S _total ) is limited by a solid thick line and is represented in the form of hexagonal fragments (figure 1 and figure 2), similar to truncated rhombuses.

найдем в виде суммы двух сегментов, ограниченных соответствующими дугами.Compare the basic version (figure 1) and the new version (figure 2). Denote the distance between base stations by l. We will be interested in the ratio of areas, therefore, different values of this parameter in FIG. 1 and FIG. 2 do not affect the calculation result by formula (3). The service areas will be circle-shaped. Area of a separate overlapping zone

we find in the form of the sum of two segments bounded by the corresponding arcs.

The basic version.

=0,061l. Таких зон на фрагменте фиг.1 насчитывается 24. Поэтому суммарное перекрытие внутри фрагмента будет S_пер=1,464l². Подставляя в формулу (3), получим степень перекрытия δ=63,54%.Consider the basic option presented in figure 1. As you can see, the hexagonal fragment contains 16 equilateral triangles, in the nodes of which there are base stations. To ensure continuous radio communication (no gaps between service areas), it is necessary to have a service area radius of R = 0.577l. The areas of individual triangles will be S ▽ = 0.144l ² , and the total area of the fragment will be S _total = 2.304l. One overlap zone has an area

= 0.061l. There are 24 such zones in the fragment of figure 1. Therefore, the total overlap inside the fragment will be S _per = 1,464l ² . Substituting in the formula (3), we obtain the degree of overlap δ = 63.54%.

New option.

Consider the new option presented in figure 2 and carry out similar calculations. The area of one pentagon is 1,661l ² , and the total area of the fragment consisting of 4 pentagons will be S _total = 6,529l ² .

The overlapping zone, as can be seen from figure 2, presents 3 types:

=0,397l²;1) the overlap of two zones of large radius, the distance between the centers of which is equal to l. This area is equal to

= 0.397l ² ;

. Эта площадь равна

=0,007l²;2) overlap of two zones of large radius, the distance between the centers of which is equal to

. This area is equal to

= 0.007l ² ;

=0,0597l².3) overlapping a zone of small radius with a zone of large radius. This area is equal to

= 0.0597l ² .

The total area of overlap of the fragment will be

+8(

+

)=1,327l².S _pep = 2

+8 (

+

) = 1,327l ² .

Hence, the degree of overlap will be δ = 19.97%, i.e. 3.182 times less than the base case.

Figure 3 shows a plan of the area covered by cellular communications, where the base stations are distributed over the vertices of the pentagons. When cellular coverage is large (comparable to the radius of the Earth) and uneven in height, it is necessary to take into account the additional advantages of the proposed placement of base stations.

It is possible to cover a flat surface only with equilateral triangles, squares and regular hexagons. However, given that the Earth’s surface is close to spherical, which can be inscribed in the dodecahedron (regular polyhedron, composed of regular pentagons), then with a slight deformation (change in internal angles) it is possible to cover various non-planar surfaces.

At the same time, a non-planar surface cannot be covered with regular hexagons. In this sense, the proposed method for constructing cellular communication has an advantage, since during deformation of equilateral pentagons, it is possible to cover both flat and uneven and convex surfaces.

Claims (1)

A method of constructing a cellular communication system, which consists in continuing continuous radio communication during the transition of a mobile station from one zone to another, characterized in that they use base stations of two radiuses of service areas, which are placed evenly at the vertices of pentagons covering the served territory without gaps, and base stations with less the radius of the service area is located at the vertices of the squares.

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