RU2619597C1 - Method of frequency resource re-use in service area of hf waves interval radio access unit - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: radio access zone is structured into sectors, and sectors are structured into elements by distance, the frequency resource reserved for service area is divided into a common set of frequencies or subbands of the zone and specific frequency sets for sectors by distance. The vertical ionospheric sounding above the node on a daily basis and oblique sounding in all sectors are performed and, based on the results of sounding, the critical frequencies of the F2 layer above the unit and the sectors are determined. Before requesting a session with a unit or when calling from a unit, the personal terminals determine their current coordinates by the built-in receivers of the satellite navigation system. When establishing a communication channel on the calling frequencies grid of the element, subscribers set a sign of radio access or direct communication and their coordinates in the calling protocol. When a forward link is requested on a unit, the fulfilment of direct links and radio access radio line space division conditions are determined, and when these conditions are met, the frequencies for the direct link are again assigned from a specific radio access set of the corresponding distance. The dedicated frequency resource (subband numbers or frequency numbers) is transmitted to subscribers over service channels on a ringing frequency grid, and subscribers perform a direct link session using the newly allocated frequency resource from a specific radio access set.

EFFECT: increased multiplicity of a limited frequency resource simultaneous re-use in the organization of direct links between subscribers in the service area of the radio access unit of the wavelengths decametric range.

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Description

The invention relates to networks and radio communication systems of the DKMV range using reflection of radio waves from the ionospheric layer F2. The invention can be used to create local radio access zones with a radius of the service area of up to 3000 km and increased efficiency of using a dedicated group of operating frequencies.

To assess the novelty and technical level of the claimed solution, we consider a number of technical means known to the applicant for a similar purpose, characterized by a combination of features similar to the claimed invention, known from the information that became public until the priority date of the invention.

In multiple radio access systems, the interaction of various groups of subscribers is performed through the nodes (base stations) of radio access. Each node is assigned a service area and a limited frequency resource. The number of simultaneously served subscribers in the zone depends on the efficiency of using the allocated frequency resource. To increase this efficiency, the service area of the node can, for example, be divided into several sectors by means of corresponding antenna patterns. In each sector, some frequency groups of a common resource of a zone can be reused simultaneously. When using direct communication between subscribers in the service area, an additional frequency resource is required, similar to the TET-RA system (ETSI EN 300 396-2 V1.3.1 (2006-09) Terrestrial Trunked Radio (TETRA); Technical requirements for Direct Mode Operation (DMO ); Part 2: Radio aspects). Direct communication channels and radio access channels for subscribers to a node in VHF - microwave systems cannot work simultaneously in the same service area at the same frequencies due to mutual interference.

Known queuing system range DKMV. The short-wave radio communication network for transmitting discrete messages according to RU Patent No. 2336635 contains a group of base stations remote from service areas that act as repeaters for the interaction of subscriber terminals located in radio access zones. Communication of subscribers through the base station is performed on one group of frequencies corresponding to long-distance or medium-sized radio paths. Direct communication without a repeater between subscribers of the zone can be established on another group of operating frequencies corresponding to short-haul radio routes. And in this case, the direct radio communication subsystem between the subscribers of the same service area cannot work at the frequencies used for radio access to the node.

There are various ways to increase the efficiency of using a limited frequency resource in the service area of a radio access node. The closest analogue is the method of total reuse of the frequency resource in the coverage area of the base station according to patent RU No. 2352085. In the known method, the coverage area of the base station (cell) is divided into several sectors corresponding to the main lobes of the radiation patterns of sector antennas. The frequency resource allocated to the zone is divided into two non-overlapping parts: a specific set of frequencies S and a common set of frequencies C. Frequencies from set S can be assigned simultaneously to several subscribers in different sectors, and the channels of these frequencies are separated due to the directivity characteristics of sector antennas. Each frequency from set C is simultaneously allocated to only one user in the zone. Thus, at frequencies of group C, subscribers who experience interference from the other sector while operating at frequencies of group S at the sector boundary are served.

To allocate frequency resources in a sector to a subscriber terminal, the channel state for this terminal is initially set based on, for example, the results of measurements of the forward link and / or the results of measurements of the reverse link. The terminal is allocated resources from a common set or sector-specific set based on the state of the channel used by the terminal. For example, if a terminal experiences strong interference from another sector, then resources from a common set can be allocated to such a terminal that have little or no interference from another sector.

A disadvantage of the known method is the fact that when organizing the direct communications subsystem within the zone and within the total frequency resource, the total number of simultaneously operating radio access channels to the node must be reduced due to the mutual influence of the direct communication channels and access channels to the node using the same frequency resource. Otherwise, an increase in the number of channels using simultaneously the common frequency resource of one sector will lead to a mutual deterioration in the quality of such channels.

Due to the limited frequency resource of the ionospheric propagation of radio waves in the DKMV range, there is a need to form direct communication channels and radio access channels to the node at the same frequencies in the same service area without their mutual influence. At the same time, the maximum possible total number of simultaneously operating channels will increase with the same allocated frequency resource without compromising the quality of direct communication and radio access channels operating at the same frequencies.

Solved by the claimed invention, the task is as follows.

The ionosphere is a natural, highly elevated, passive radio wave repeater. The length of the radio lines with a single reflection from the F2 layer is from 0 to 3000 km. But the working frequency range of ionospheric channels is insignificant and ranges from 10 to 30 MHz, depending on the state of the reflecting layer. The change in the state of the ionosphere has daily and annual cycles and is determined by the parameters of solar activity and current solar illumination. Modern technologies for the formation, processing, and emission of radio signals make it possible to create efficient network structures using ionospheric channels. The potential channel capacity of such structures is determined by strict physical and administrative limitations of the frequency resource.

Due to the limited frequency resource of the ionospheric propagation of radio waves in the DKMV range, there is a need to form direct communication channels and radio access channels to the node at the same frequencies in the same service area without their mutual influence. At the same time, the maximum possible total number of simultaneously operating channels will increase with the same allocated frequency resource without compromising the quality of direct communication and radio access channels operating at the same frequencies.

The claimed invention is aimed at solving the problem of increasing the total amount of traffic over ionospheric radio channels in the service area of the radio access node for a given limited frequency resource.

The invention as a technical solution is expressed in the following set of essential features, sufficient to achieve the above result.

The method of reusing the frequency resource in the service area of a radio access node of the DKMV range, namely, that the radio access zone with a radius of up to 3000 km of one node is divided into several sectors in azimuth, and each sector into several elements in range, while elements of all sectors adjacent to the location of the node is combined into one circular region with a radius of up to 500 km, and the frequency resource allocated to the zone is divided into two sets of operating frequencies: a common set of zones and a specific set of sectors, characterized in that o a specific set of sectors is additionally divided into several specific sets by range, according to the daily schedule, vertical sounding of the ionosphere above the node and inclined sounding in all sectors with dedicated stationary subscribers are performed, then the critical frequencies of the F2 layer above the node and sectors within a radius of 1500 are determined by sounding km from the node and build a map of the distribution of the maximum applicable frequencies above the service area, while all subscribers registered by the node in its service area , before requesting a session with the node or when calling from the node, their current coordinates are determined by the built-in receiver of the satellite navigation system, and when requesting a communication channel on the ring frequency of their element, in addition to the general parameters of the system’s request, they establish in the protocol the sign of radio access or direct communication and their coordinates, and on the node, based on sensing and navigation data, determine the spatial parameters of the requested radio line and the necessary range of operating frequencies, and when requesting a line with the ides on the node determine the fulfillment of the conditions for the spatial separation of the channels and, when these conditions are met, the frequencies are reassigned to the direct communication channel from a specific set of radio access of the appropriate range, and the allocated frequency resource is transmitted to subscribers over the service channels on the ring of calling frequencies, while the subscribers complete the session direct communication using a re-allocated frequency resource from a specific set of radio access.

The technical result provided by the implementation of the claimed combination of essential features of the claimed invention is to increase the multiplicity of the simultaneous reuse of a limited frequency resource when organizing direct communications between subscribers in the service area of a radio access node of the DKMV range.

The invention is illustrated by drawings, where in FIG. 1 shows one of the possible structuring of the radio access zone, in FIG. 2 is an example of a block diagram of an implementation of the claimed method.

In FIG. 1, a central circular region is highlighted from which access is performed by anti-aircraft radiation. The central region is assigned a specific set of frequencies S ₀ for anti-aircraft radio links. Each of the sectors of the zone is divided into three additional elements in range, which are assigned specific sets of frequencies S ₁ , S ₂ , S ₃ corresponding to the distance of the subscriber from the node.

The positions in the figures indicated:

1 - radio access node;

2 - subscriber terminals in the radio access mode (ATRD) operating at the same frequencies ƒ _З from a specific set of S ₃ ;

3 - a pair of subscribers in direct communication mode (ATPS) at the same frequencies ƒ _З from a specific set of S _3;

4 - a pair of subscribers in direct mode at frequencies from a specific set of S _0;

5 - a pair of subscribers in direct mode at frequencies from the common set C;

6 is a block that allows you to structure the service area and distribute the allocated frequency resource;

7 is a block that allows to perform sounding procedures according to the daily schedule and form a current map of actual values of critical frequencies;

8 is a block that allows you to perform the service procedure of establishing communication on a grid of calling frequencies;

9 is a block that allows using spatial data and navigation data to determine the spatial parameters of the requested radio line and the required operating frequency range;

10 is a block that allows you to perform a conditional transition on the functional sign of the radio line;

11 is a block that allows you to perform a conditional transition of the radio access line for channel quality;

12 is a block that allows you to perform a conditional transition to assess the location of subscribers and the conditions of the spatial separation of channels;

13 is a block that allows you to assign operating frequencies from a common set;

14 is a block that allows you to reassign the frequencies of a specific set;

15 is a block that allows you to assign frequencies from a common set;

16 is a block that allows you to report operating frequencies to correspondents.

The claimed method is as follows.

The basis of the proposed method are the following known physical phenomena. (Yakovlev O.I., Yakubov V.P., Uryadov V.P., Paveliev A.G. Radio wave propagation: Textbook / Edited by O.I. Yakovlev. - M.: LENAND, 2009. - 496 p. ) When the radio wave is obliquely incident on the ionosphere of the maximum range of one jump, there corresponds a certain angle θ _{0 max} between the propagation direction and the vertical in the reflection region. This angle corresponds to a certain maximum reflection frequency ƒ _{n max} , which is the upper limit of the working frequency range for the corresponding sector of the service area. The corresponding maximum range sets the limit of the radius of the service area of one radio access node of the DKMV range for radio lines using only one reflection from layer F2 (mode 1F2). Each length of the radio link corresponds to a certain maximum applicable frequency (MUF). For a radio line with mode 1F2, an operating frequency range can always be found that excludes the appearance of a mode 2F2 with two reflections from the ionosphere (Zaitsev V.V., Krukovskaya I.Ya. Selection of operating frequencies in the service area of a radio access node of the DKMV band. Information and Space. 2015, No. 4, p. 10-12.)

When arranging an oblique radio access line of length L with mode 1F2 between the node and the remote subscriber at a frequency ƒ _p near the MUF _L, there is an area between the transmitter and receiver of this line called the silence zone, or “dead zone”, in which there is no transmitter signal. This effect is caused by the excess of the selected operating frequency ƒ _p over the MUF of shorter radio links. Operating frequency radio waves are not reflected from the ionosphere regions closer to the transmitter and do not reach the earth's surface in the silence zone. If any other subscriber terminal is in the silence zone, it cannot receive the signals of the radio line L. The subscriber terminal from the silence zone of ATS 3 can create a direct line with its correspondent at a distance corresponding to L at the same frequency ƒ _r . If the second correspondent of ATPS 3 is also in the silence zone of the radio access line, then the correspondents of the latter do not receive signals of the direct communication line. This effect can be called the spatial separation of channels occupying the same frequencies in the common service area of the radio access node. A feature of the effect is its independence from the directivity characteristics of sector antennas. The effect is manifested even if the zone is served by an antenna (or a set of antennas) with a pie chart in the azimuthal plane.

In FIG. 1 ATRD 2 are located at approximately the same large distance from the node and can operate in the radio access mode at the same frequencies ƒ _З from a specific set of S3 due to the directivity of sector antennas. The ATPS 3 pair is located in silence zones for radio access frequencies ƒ _З , between the node and АТРД 2, but the distance between АТПС 3 corresponds to the working radio access frequencies ƒ _З and these subscribers can establish direct communication at these frequencies. Frequency multiplication ƒ _{З is} further increased due to spatial separation of channels due to the effect of the silence zone.

ATPS 3 are located at a relatively close distance between each other (300-500 km), but are significantly removed from the central zone. These subscribers can use for a direct connection of the frequency of anti-aircraft radiation of a specific set S ₀ and the frequency of use of this set also increases

These considerations are also valid for elements of sectors with specific sets S ₁ , S _{2, the} frequency of use of which also increases. If one of the direct communication subscribers is not in the silence zone of the corresponding radio access line, this pair is allocated frequencies from the general set C for direct communication.

Mandatory new conditions for the implementation of the technical effect are:

- periodic monitoring of the state of the ionosphere over the service area to determine the MUF radio lines and the operating frequency range;

- determining the location of subscribers to decide on the possibility of using radio access frequencies for the direct communication channel.

Periodic monitoring of the ionosphere over the service area of the node can be performed by known means and methods of vertical sounding over the node and oblique sounding between the node and subscribers in different azimuths. The determination of the location of subscribers in the service area can be performed using the navigation receivers built into the subscriber terminals of one of the existing satellite navigation systems. The subscriber terminals can transmit data about their location to the node when performing the procedure for establishing communication adopted for a particular system.

In FIG. 2 shows an example of a flowchart of a process for implementing the proposed method. Block 6 structures the service area by sectors and sector elements and divides and periodically adjusts the allocated frequency resource to the frequencies of the common set C and the frequencies of specific sets S ₀ , S ₁ , S ₂ , S ₃ . Block 7 periodically performs daily sounding of the ionosphere over the service area according to the daily schedule and generates a current map of the actual values of critical frequencies. Block 8, upon request from a node or subscriber terminal, performs the procedure of establishing communication on the calling frequency grid, clarifies the position of the terminal according to the data of its navigation receiver, determines the functional purpose of the radio line — direct communication or radio access, and also determines the quality of the planned channels using the communication establishment protocol. Block 9 from the sensing data and navigation data determines the spatial parameters of the requested radio link and the required operating frequency range. Block 10 analyzes the functional sign of the radio link and performs a conditional transition and fulfills the conditions for the spatial separation of the channels. If there is a sign of direct communication, then block 12 performs an assessment of the location of subscribers and the fulfillment of the conditions for the spatial separation of channels, after which it performs a conditional transition. If both subscriber terminals are in the silence zone of any element of the radio access sector, block 14 reassigns one of the radio access frequencies of this element. If not, block 150 assigns the frequency from set C to this pair.

If there is a sign of radio access, block 11 analyzes the quality of the channels and performs a conditional jump. If the channel quality is satisfactory, the unit selects the operating frequencies from the corresponding specific set. If the quality of the channels is poor, block 13 selects the operating frequencies from the common set. After determining the operating frequencies of the radio link, block 16 informs their respective correspondents.

The possibility of industrial application of the claimed technical solution is confirmed by the known and described in the application means and methods by which it is possible to carry out the claimed invention in the form described in the claims. The claimed device can be implemented industrially using well-known hardware and software.

Claims (1)

The method of reusing the frequency resource in the service area of a radio access node of the DKMV range, namely, that the radio access zone with a radius of up to 3000 km of one node is divided into several sectors in azimuth, and each sector into several elements in range, while elements of all sectors adjacent to the location of the node is combined into one circular region with a radius of up to 500 km, and the frequency resource allocated to the zone is divided into two sets of operating frequencies: a common set of zones and a specific set of sectors, characterized in that The specific set of sectors is additionally divided into several specific sets of range, according to the daily schedule, vertical sounding of the ionosphere above the node and inclined sounding in all sectors with dedicated stationary subscribers are performed, then the critical frequencies of the F2 layer above the node and sectors within a radius of 1,500 km are determined by sounding from the node and build a map of the distribution of the maximum applicable frequencies above the service area, while all subscribers registered by the node in its service area are not By requesting a session with a node or when calling from a node, their current coordinates are determined by the integrated receiver of the satellite navigation system, and when requesting a communication channel on the ring frequency of their element, in addition to the general parameters of the system’s request, they establish in the protocol a sign of radio access or direct communication and their coordinates , and on the site spatial data of the requested radio line and the necessary range of operating frequencies are determined from the sounding data and navigation data, and when requesting a direct connection on the node, the fulfillment of the conditions for the spatial separation of the channels is determined and, when these conditions are fulfilled, the frequencies for any direct communication channel are reassigned from any specific set of radio access of the appropriate range, and the allocated frequency resource is transmitted to subscribers over the service channels on the ring of calling frequencies, while the subscribers perform a direct session communication using a re-allocated frequency resource from a specific set of radio access.

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