RU2251809C1 - Radio communications method - Google Patents

Abstract

FIELD: radio communications.

SUBSTANCE: in each cell radio-signals of transmitters of base station system thereof cover at least two zones, one of which is inner zone, placed inside contour of radio-covering of cell and one into another, with zone contours, quasi-similar to contour of cell radio-covering, without any mutual intersections, while each zone is covered by radio-signals of radio-frequencies, selected for this zone, and also priority access for subscribers being in inner zone is provided, especially to radio-frequencies, assigned for servicing inner zone. Transceivers receive and transmit radio-signals, providing for radio-covering of inner zone, close to circular, at least one assigned radio-frequency and sector-wise radio-covering of outer zone at other radio-frequencies, assigned for servicing each sector.

EFFECT: higher capacity of mobile communications, frequency resource savings, decreased system interferences, guaranteed electromagnetic compliance with radio-electronic means of other communication systems.

3 cl, 4 dwg, 1 tbl

Description

The invention relates to the field of communication, and more particularly to methods of radio communication in a communication system based on the principle of frequency reuse with multiple access.

An increase in the number of mobile operators and subscribers aggravates the problem of rational use of the frequency resource, and this requires the development of ways to increase the efficiency of frequency reuse.

The invention allows to increase the capacity of the communication network for a given number of frequency bands (radio frequencies) allocated for the system or to provide the specified capacity of the system with a smaller number of radio frequencies, i.e. save frequency resource and, consequently, the number of transceivers, improve communication quality, providing intersystem electromagnetic compatibility (EMC) while maintaining intrasystem EMC, significantly reduce the total radiated power of transceivers, implement communication network planning options depending on the task and goals and increase overall technical and economic efficiency of the system, taking into account all the components that affect its technical indicators and full cost.

The claimed invention relates to a cellular communication system built in the form of a set of cells covering the served territory. Simplistically, the cell is represented in the form of a hexagon, in the center of which there is a base station system (SBS), consisting of several base stations (BS), serving all subscribers (otherwise, subscriber terminals (AT)) within their cell. When AT moves from one cell to another, its service is transferred from one BS to another or from one SBS to another (handover). All SBS systems are closed at least to one switching center (CC), which controls the entire system and provides access to other communication systems. General control over the operation of the Central Committee and the system as a whole is carried out from the central controller, which is part of the Central Committee and has powerful mathematical software, including a reprogrammable part.

The real contours (boundaries) of the cells have the form of irregular curves, depending on the propagation and attenuation of the radio waves, and are not clearly defined, the position of the BS also only approximately coincides with the center of the cell.

The principle of frequency reuse is the basic principle of a cellular communication system, which allows to significantly increase the capacity of the system and consists in the use of different frequency bands in cells close to one another and in their repetition through several cells.

In the practice of cellular communication, three main methods of multiple access are used - sharing a limited portion of the frequency spectrum by many users: with frequency, time and code separation of communication channels (for example, RF patent No. 2104615, class N 04 V 7/26). Also use a frequency hopping (US Pat. RF No. 2119255, class.).

For any multiple access, the capacity of a radio communication system with the reuse of frequency bands is increased in several main ways:

1) Move to digital information processing and a more advanced access method - from frequency to time and code.

2) They increase the frequency repeatability, decreasing the service areas of individual BSs (cell fragmentation) and increasing their density in areas with heavy traffic. This is achieved by reducing the radiation power of both BS and AT, lowering the antenna suspension height and increasing the angle of their radiation pattern (M.V. Ratynsky. Fundamentals of cellular communications. M: Radio and communications, 2000. p. 82; Technologies and means Communications, 2002, No. 2, p. 40).

3) To reduce the flow of service flows caused by fragmentation, it is proposed to use multilevel systems for building a network with services in macro cells of fast moving ATs, and in microcells - slow moving ATs. With low traffic, the cells are not crushed, but enlarged.

4) Apply multi-sector SBS (3, 6, 9, 12 sectors) using directional antennas in sectors (US Pat. RF No. 2172072, class N 04 V 7/26).

5) It is intended to use adaptive radio frequency assignment for frequency and time channel separation. In this case, the frequency resource is not allocated in a predetermined way between the cells of the cluster, but all or partially is at the operational disposal of the Central Committee, which allocates them for use by the base station as calls arrive, i.e. in accordance with real traffic, but subject to the necessary territorial-frequency separation (for example, M.V. Ratynsky, cit., p. 83; pat. of the Russian Federation No. 2154901, class N 04 V 7/26).

6) Increase the number of allocated radio frequencies.

To increase the noise immunity, radio communication systems with identical frequency bands are removed from each other by a distance that provides a given level of co-channel, intra-system interference (M.V. Ratynsky. Fundamentals of cellular communications. M., Radio and communications. 2000, section 2.4.2).

Known methods of radio communication are aimed at increasing capacity and reducing intra-system interference of communication systems. However, the speed of development of cellular communications and the investment in its creation and operation are so great that constant further development, improvement, and the search for additional opportunities to increase the technical and economic efficiency of communication systems are required.

As a prototype, the selected radio communication method according to the patent of the Russian Federation No. 2223602, class. Н 04 В 7/26, based on the principle of frequency reuse in a communication system, in which the entire service area consisting of a set of cells is covered with radio signals, in each cell at least two zones are covered by the radio transceivers of its base station system, one of which is internal, embedded in the radio coverage circuit of the cell and one into the other, with the contours of the zones, quasi-similar to the radio coverage of the cell, without intersecting with each other, each of the zones being covered by radio frequency signals, divided for this zone, while providing subscribers access a priority in the internal zone, primarily to the frequencies allocated for maintenance of the inner zone.

The known method does not exhaust the potential for increasing the capacity and reducing the intra-system interference of communication systems, saving frequency resource and therefore does not use the reserves of increasing the technical and economic efficiency of the communication system.

The invention is aimed at increasing the capacity and reducing intra-system interference, saving frequency resource and increasing the technical and economic efficiency of the communication system.

Distinctive features of the claimed invention from the prototype are that it allows, for example, with a slight increase in the number of frequencies and maintaining the EMC, significantly increase the traffic of the communication system.

A radio communication method based on the principle of frequency reuse and containing the essential features of the prototype is proposed: radio coverage of the entire service area, consisting of a set of cells, in each cell, at least two zones are covered by the radio transceivers of its base station system, one of which is internal embedded in the radio coverage of the cell and one into the other, with the contours of the zones, quasi-similar to the radio coverage of the cell, without intersecting with each other, each of which cover the radio frequencies allocated to this zone, thus providing subscribers access priority in the internal zone, primarily to radio frequencies allocated to service the inner zone.

Other significant distinguishing features from the prototype are the following: base station system transceivers transmit and receive radio signals, providing close-to-circular radio coverage of the inner zone at least on one allocated radio frequency and sector-wide radio coverage of the outer zone on other radio frequencies allocated for serving each sector.

где m - число секторов в ячейке, k - число радиочастот, выделенных для обслуживания одного сектора, n - число радиочастот, выделенных для обслуживания внутренней зоны.In addition, the ratio of the radius R _{2 of the} inner zone to the radius R _{1 of the} outer zone is chosen mainly in the range

where m is the number of sectors in the cell, k is the number of radio frequencies allocated for serving one sector, n is the number of radio frequencies allocated for serving the internal zone.

Transceivers of base station systems also transmit and receive radio signals, providing radio coverage of internal areas at radio frequencies farthest from radio frequencies occupied by electronic means of other radio communication systems located in the vicinity of this radio communication system.

The proposed method of radio communication increases the technical and economic efficiency of the communication system due to the transmission and reception of radio signals in the inner, close to circular, zone, at least one radio frequency and the possibility of using this radio frequency in other cells. This allows you to increase capacity, reduce intra-system interference, save frequency resource and as a result reduce the cost of cellular communication systems, and in some situations generally ensure the possibility of its functioning.

Below the invention is described in more detail with reference to the drawings and the table, schematically illustrating the implementation of the claimed method.

The method applies to both existing and designed cellular communication systems of various standards and can be applied in conjunction with other known methods of increasing the efficiency of using a frequency resource, supplementing and developing them and giving, as shown below, a significant technical and economic effect.

The proposed method is as follows.

The method extends to a communication system built in the form of cells with SBS, conventionally located in the center of each of them. SBS provides radio communications to all ATs located within the cell. All SBS are functionally connected to a common CC, which transfers service from one SBS to another when the AT moves from one cell (sector, zone) to another.

SBS transceivers (PP), and, respectively, subscriber terminals located within the cell transmit and receive radio signals from radio frequencies from the frequency bands allocated for the operation of the radio communication system, together covering the entire area of the cell. The required number of frequency bands used in the cell is repeated through several cells according to the scheme providing the required co-channel electromagnetic compatibility, as is customary in communication systems based on the principle of frequency reuse.

Each cell is divided into at least two zones of radio coverage, one of which is internal with a conditional radius R ₂ , and the second is external to it with a conditional radius R ₁ . All radio coverage zones are embedded in the radio coverage circuit of the cell and one into the other and have contours that are quasi-similar to the radio coverage circuit covering the cell. The contours of the radio coverage areas should not overlap with each other. The inner zone has the largest number, and the outer one has the first number. In this case, it is crucial that each of the zones is covered by radio signals of the radio frequencies allocated for servicing this zone in the cell.

The required number of radio frequencies used in the cell is reused in each other cell or through several cells according to optionally identical circuits providing the required communication quality, channel-wide electromagnetic compatibility.

The following are steps to ensure AT access to radio frequencies. Namely, the AT access to the radio frequencies is carried out by a known means of radiofrequency allocation (for example, from US Pat. RF No. 2154901, class H 04 B 7/26) specified in the particular communication system, but with the following priority. First of all, they provide access for ATs located in the inner zone to the radio frequencies allocated for servicing the inner zone. These radio frequencies may not be available in two cases: 1) AT is outside the radio coverage of these radio frequencies, and 2) AT is in the radio coverage of these radio frequencies, but they are fully occupied. In this situation, the prototype provides access to the radio frequencies allocated for servicing the external zone (in the case of two zones). With a larger number of zones, this process is sequentially repeated until access to the radio frequencies allocated to provide radio coverage of the entire area of the cell.

The control signals operate on the entire cell on specially allocated radio frequencies of the external zone.

To achieve the technical result of the invention, the following actions are taken.

SBS transceivers transmit and receive radio signals providing close to circular radio coverage of the inner zone at least on one radio frequency allocated for servicing the ATs located therein. Sector radio coverage of the outer zone is provided at other radio frequencies allocated for each sector.

The implementation of the prototype method is schematically shown in figure 1, and the inventive method is shown in figure 2, 3, 4. Radio communication systems are presented in the form of fragments of a set of cells covering the served territory.

In Fig. 1, the cells consist, for example, of two zones: internal (internal), external (external), covered by the radio coverage circuit (circuit). The radii of the radio coverage areas are shown.

The implementation of the proposed method is demonstrated on a simple example of a 4-element, 3-sector cluster (figure 2, 3, 4). The cells of one cluster are indicated by the letters A, B, C, D. Inside each cell, for example, two radio coverage zones with SBS, conventionally located in the center of the cell, are shown. Each software transmits and receives radio signals only at dedicated radio frequencies. The inner zone is close to circular and in figures 2-4 is indicated by the number 13. For its service, at least one radio frequency f _{1 is} allocated in all cells of the cluster (figure 2). The outer zone in the cell is formed in the form of three sectors, the radio frequencies allocated for their maintenance are indicated by the numbers 1-12. The radio signals of all radio frequencies 1-12 and f ₁ cover the entire cluster.

The AT access to radio frequencies will be shown using an example of one cell. Let AT be in the inner area of the radio coverage served by the radio frequency f ₁ , at point E. Then he is granted access primarily to the radio frequency f ₁ . If the radio frequency f ₁ turns out to be occupied, then the ATs provide access to the second stage — to the radio frequency 8 allocated for serving the sector to which point E.

Now let AT be at point F in the outer zone in the sector with radio frequency 8. Then radio frequency f ₁ is inaccessible to it and access is given to radio frequency 8.

In the vicinity of this radio communication system, there may be electronic means of other radio communication systems operating at certain radio frequencies. In this case, the transceivers of base station systems transmit and receive radio signals, providing radio coverage of the internal zones at the radio frequencies farthest from the radio frequencies occupied by electronic means of other radio communication systems located in the vicinity of this radio communication system.

Density AT (the number of AT per unit area) can be considered with sufficient accuracy the same throughout the served territory.

The ratio of the radii of the inner and outer zones obtained from the condition of equal accessibility of AT to radio frequencies for a homogeneous network model has the form (notation is given above)

For a real network, this ratio is chosen mainly in the range

In practice, the number of radio frequencies is set to serve the respective radio coverage areas.

The inventive method allows a fairly flexible approach to network planning, depending on the specific situation and the task. For example, in a cluster for servicing the internal zones of cells, you can specify: 1) the same radio frequencies f ₁ for all zones (Fig. 2), 2) the same radio frequencies for remote zones (for example, f ₂ in cells B and D, Fig. 3) and different - for zones closer to each other (for example, f ₁ and f ₃ in cells A and C, figure 3), 3) different radio frequencies f ₁ , f ₂ , f ₃ , f ₄ for all zones cluster (figure 4). You can use the reduced power of the transceivers, which gives additional environmental and technical and economic benefits. With increasing cluster dimension, within the framework of the proposed method, additional options for specifying radio frequencies, powers and their combinations for servicing internal zones appear.

Effective and high-quality operation of the cellular radio communication system with the provision of intra-system EMC and EMC with other radio electronic means, for example, with aerodrome short-range navigation and landing facilities, is carried out in an optimal manner taking into account the specific requirements for this radio communication system.

Using the claimed method of radio communication can increase the capacity of the communication system. We show this with a few simple examples:

1) A cellular radio communication system consists of four-element three-sector clusters (an example of which is shown in FIG. 2). If the inner zone according to the claimed method is not provided, then 12 radio frequencies are required and the traffic of one cluster is also ~ 12. Let one radio frequency be allocated to serve one sector of the outer zone, and 1, 2, or 3 radio frequencies should be allocated to serve the inner zone. Then, provided that AT is equitable, the addition of one radio frequency to the internal zone in the cluster increases traffic by 33%, two by 67%, and three by 100%. With an increase in the number of radio frequencies in the inner zone, R ₂ grows and it is necessary to control the conditions for ensuring the intra-system EMC.

2) The radio communication system was constructed as in Example 1, but 2 radio frequencies were allocated for serving the sector. If the inner zone according to the claimed method is not provided, then 24 radio frequencies are required and the traffic of one cluster is also ~ 24. Let 1, 2 or 3 radio frequencies be allocated for servicing the inner zone. Then, provided that AT is equally accessible, adding one radio frequency to the cluster in the internal zone increases traffic by 17%, two by 33%, and three by 50%. With an increase in the number of radio frequencies in the inner zone, R ₂ grows, but the provision of an intra-system EMC is somewhat facilitated in comparison with Example 1.

3) The radio communication system was constructed as in Example 1, but 3 radio frequencies were allocated for serving the sector. If the inner zone according to the claimed method is not provided, then 36 radio frequencies are required and the traffic of one cluster is also ~ 36. Let 1, 2 or 3 radio frequencies be allocated for servicing the inner zone. Then, provided that AT is equitable, the addition of one radio frequency to the cluster in the internal zone increases traffic by 11%, two by 22%, and three by 33%. With an increase in the number of radio frequencies in the inner zone, R ₂ grows, but the provision of an intra-system EMC is facilitated in comparison with examples 1 and 2.

The results of evaluating the effectiveness of the proposed method for these three examples are shown in more detail in the table.

The claimed radio communication method is universal and can be applied in combination with other methods when using on the SBS both antennas with a circular radiation pattern and sector antennas, as well as in multi-level repetition schemes of a cellular communication network. We also note the following rather important circumstance. When creating a cellular communication network, due to high investment, operators at the initial stages of the construction of their systems seek to provide the maximum radio coverage area with a small amount of AT. The subsequent increase in subscriber capacity by increasing the number of SBS, their sectorization and multiplying the number of channels occurs after the system is put into operation. This approach requires a simple increase in the number of SBS software, but it can entail a complete change in the structure of their antenna-feeder equipment (AFO). In order to minimize the cost of upgrading the AFO, which includes not only the cost of the equipment itself, but also quite laborious installation work, it is necessary at the initial stage of network design to provide ways for further development of the system as a whole and the possibility of changing the structure of individual SBS. The application of the claimed method of radio communication can significantly reduce these difficulties, and in some cases eliminate them.

Thus, the distinguishing features of the proposed method of radio communication provide the emergence of new properties not achieved in the prototype and analogues. The analysis made it possible to establish: analogues with a set of features that are identical to all the features of the claimed technical solution are absent, which indicates the conformity of the claimed communication method to the “novelty” condition.

The results of the search for known solutions in the field of communication in order to identify features that match the distinctive features of the prototype of the claimed method of radio communication, showed that they do not follow explicitly from the prior art. Also, the popularity of the influence of the actions provided for by the essential features of the claimed invention on the achievement of the specified result was not revealed. Therefore, the claimed invention meets the condition of patentability “inventive step”.

Claims (3)

1. A radio communication method in a cellular communication system in which the entire served territory consists of a set of cells, each of which has at least two zones, one of which is internal, based on the principle of reusing frequencies covering the entire serving territory, when wherein at least two zones are covered by the radio signals of the base station transceivers, one of which is internal, embedded in the radio coverage loop of the cell of the other, with the contours of the coverage zones of the radio signals quasi-like the cell coverage loop without intersecting with each other, and each of the zones is covered by the radio signals of the radio frequencies allocated for this zone, while providing priority for access of subscribers located in the internal zone, primarily to the radio frequencies allocated for servicing the internal zone, characterized in that base station transceivers transmit and receive radio signals, providing close-to-circular radio coverage of the inner zone at least at one allocated radio frequency and sector-wide radio coverage of the external zones on other radio frequencies allocated for serving each sector. 2. The method according to claim 1, characterized in that the ratio of the radius R _{2 of the} inner zone to the radius R _{1 of the} outer zone is chosen mainly in the range

where m is the number of sectors in the cell, k is the number of radio frequencies allocated for serving one sector, n is the number of radio frequencies allocated for serving the internal zone. 3. The method according to claims 1 and 2, characterized in that the transceivers of the base station systems transmit and receive radio signals, providing radio coverage of the internal zones at radio frequencies farthest from the radio frequencies occupied by electronic means of other radio communication systems located in the vicinity of this radio communication system.

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