RU2231927C1 - Method for radio communications with mobile objects - Google Patents

Abstract

FIELD: multiple-access radio communication systems.

SUBSTANCE: change-over to new operating frequency is permanently made during each time step at change in frame composition and length and time interval numbers related to one movable object are changed in each frame, data arriving from sensors of one mobile object during adjacent time steps are additionally processed to enable determination of mobile object characteristics such as location and motion parameters, to estimate existing situation, and to take decision on reliability of data, elimination of address pulse transmission from central station to mobile objects, operation of transceivers in each exchange frame at respective frequency known by mobile radio communication object from central-station information unit, on reduction of frame length as function of number of mobile objects and, hence, on increase in rate of updating information about mobile objects.

EFFECT: enhanced noise immunity of communication line and data exchange security.

3 cl

Description

The invention relates to radio communication systems with multiple access.

Known methods of radio communication with moving objects used in air traffic control systems (ATC).

In the ACARS communication, addressing and reporting system [1], a radio communication method was used, consisting in the fact that from the central station (CA), after establishing communication with mobile objects - aircraft (AC) that entered the control zone, an application information block is issued to contact. It indicates the type of data from the aircraft of interest to the consumer of information, and the rate of exchange with the central station. Data is transmitted at the same frequency for all aircraft located in the control zone (for the Russian Federation this frequency is 131, 725 MHz). Information is reset from the aircraft to the CA before it leaves the control zone.

The disadvantages of this method include the following.

With the simultaneous response of several aircraft, collisions are possible, which reduces the speed of information exchange and the reliability of data reception. In addition, working at a constantly allocated frequency in some practical cases, for example, in a complex electromagnetic environment, will lead to an increase in the number of false messages, which also reduces the transmission speed of messages.

In another automated communication system VDL-4 [2], the central station distributes 4,500 time slots between aircraft, each of which must exchange data from the CA with a specific aircraft. The total frame duration is 1 min. After a minute, the data exchange process is resumed with the preservation of the slot numbers that were assigned by the CA in the previous frame.

The disadvantage of this analogue is that data is exchanged only at one operating frequency, while it is impossible to request additional data from the aircraft within 1 min.

The closest analogue is the method of radio communication with mobile objects according to copyright certificate No. 1596468, which is selected as a prototype.

The method of radio communication with mobile objects is that when exchanging information with mobile objects located in the coverage area of the central stationary station, an information block containing the address of the peripheral station is transmitted from it to the peripheral mobile stations at a frequency f ₁ . If the address of the peripheral station and transmitted from the central station addresses from the peripheral station at a frequency f ₂ transmit an information block to the central station. Periodically from the central station at a frequency of f ₃ transmit a clock signal for all peripheral stations. Using this signal, at each peripheral station, a number is randomly selected from a finite set of integers indicating the number of the response interval in which its address is transmitted from the peripheral station at frequency f ₄ to the central station, after which the signal is transmitted at frequency f ₃ after undistorted reception confirmation of admission. In the case of a distorted reception of the address, an acknowledgment signal is not transmitted, and at the peripheral station, the choice of the response interval number is repeated until confirmation of the correct acceptance of the address is received. After that, the peripheral station operates at frequencies f ₁ , f ₂ during an information exchange session with the central station. At the end of the exchange of information, the peripheral station switches to work at frequencies f ₃ and f ₄ . The clock signal is transmitted in the form of an encoded signal representing the address of the central station.

The disadvantages of the prototype are the need for the presence on the aircraft and moving objects simultaneously four transceivers; the presence of a radio signal periodically emitted from the DS at a frequency f ₃ , which worsens the electromagnetic environment in the radio communication zone, as well as a complex algorithm for exchanging data between the DS and moving objects due to the need to synchronize the system with the DS.

The objective of the invention is to increase the noise immunity of the communication line and the secrecy of data exchange.

The specified technical result is achieved by the fact that in the method of radio communication with mobile objects, which consists in transmitting from a central station (CS) a block of information containing the data embedded in it, receiving it on mobile objects (PO) and transmitting an information signal from mobile objects containing confirmation about receiving a block of information from the CA and data from the sensors of a moving object, delayed relative to the block of information received from the central station, code codes are introduced into the information block from the central station e groups of the type of work, type of requested data, nominal of the working frequency for the next exchange frame and the start time of the next frame, the data in the information signal from each of the moving objects is distributed over time intervals, depending on the number determined by the code group of the type of work, starting from the moment the time specified by the code group of the start time of the next frame, the mutual synchronization in time of the central station and moving objects is carried out using the time scale of the global navigation system, the frame duration T is determined based on the purpose of the radio communication system, but not more than

T = (1 + Nn) · τ + t for τ≥mσ _t ,

where N is the number of POs, n is the number of bits in the message with PO, t is the maximum total time of propagation of the radio signal along the CS-PO-TsS line and twice the duration of the message from the TS, σ _t is the relative mean square error of determining the current time interval, τ - duration of a single transmission of information, m - coefficient (greater than one), depending on the purpose of the radio communication system.

The method of radio communication with moving objects is implemented as follows. When exchanging information with the mobile units (ME) located in the base station coverage area (CA) at the initial time from it to the frequency f ₁ is transmitted to mobile units the block of information comprising job type, data type, start time, nominal operating frequency to the next frame of exchange. In pre-tuned receiving devices at a known frequency, the software receives, processes the information block and issues to the DS at a frequency f ₂ , determined by the software according to the information from the DS, an information response block confirming the reception quality of the information block from the DS and the necessary data from the sensors of the moving object . Data from each moving object is transmitted in the corresponding time interval, the number of which for each frame is determined by the received code group of the type of work. In accordance with the message received from the CA, one of the operating options is selected in the software for the next frame or for the next several frames, due to the fact that the CA and the software work in a single previously known data exchange algorithm. For example, a block of information is transmitted at predetermined (using a block of information from a CA) time points. The beginning of the interval is tied to the exact start time transmitted from the CA in the code group of the start time of the next frame. Then, a message is issued from the DS to mobile objects in the radio communication zone at a frequency of f ₃ , and a message is transmitted at a frequency of f ₄ from the software in the corresponding time intervals, and so on. Moving objects included in the radio communication zone, having an exact plan for assigning frequencies to the reference time, exchange data with the CA starting from the next frame. Mutual synchronization in time of the CA and moving objects is carried out using the timeline of the global navigation system, for example GPS, GLONASS or other more powerful sources of the reference time. The time for issuing a new information block from the CA is determined based on the purpose of the radio communication system, but no later than after an interval

T = (1 + Nn) τ + t for τ≥mσ _t ,

where N is the maximum number of software expected in the radio communication zone, n is the number of bits in the message with the software, t is the maximum total propagation time of the radio signal along the line “DS-ON-DS” and twice the duration of the message from the DS, σ _t is the relative mean square error determining the current time, T is the frame time, τ is the duration of a single transmission of information, m is a coefficient (greater than one), depending on the purpose of the radio communication system. This condition determines the stable reception and processing of exchange data. The option of further work for the next frame or for several next frames on the CA is determined by the evaluation of the information received from the software in the previous frames. The information received at the CA is checked for validity and then, according to the data from the sensors of the moving object, in the next frame, the presence of impossible combinations characterizing, for example, the emergency state of the moving object, the deterioration of the parameters of the transceivers, the location of the object on the border of the coverage area of the CA, the movement of the moving object during the frame is determined to a distance that cannot be overcome at given software speeds and other parameters. Based on these checks, a decision is made on the reliability of the information received. In accordance with the communication algorithm discussed above, software tools work on transmission only in the allotted time intervals, and the rest of the time on reception. Therefore, after receiving and processing information on the appropriate software, messages from other software located in the zone of stable communication of the CA are used. Data from the CA provides the consumer of information the more often, the shorter the frame duration, which allows the CA and the consumer of the information to display more accurate information about moving objects in the radio area.

The advantages of the proposed method in terms of increasing the noise immunity of radio communications is provided by:

- constantly switching each cycle to a new operating frequency when changing the composition and duration of the frame;

- change in each frame of the numbers of time intervals related to one moving object;

- additional processing of data from the sensors of one moving object in adjacent clock cycles, which allows to determine its characteristics, for example, location and motion parameters, evaluate the existing situation and decide on the reliability of the data;

- exceptions for the transfer of address packages from the CA to mobile objects;

- the operation of transceivers in each exchange frame at the corresponding frequency known to mobile radio objects from the information block of the CA;

- reducing the duration of the frame, depending on the number of software, and therefore the increase in the rate of updating information about moving objects.

Sources of information

1. B.I. Kuzmin. Digital Telecommunication Networks and Systems, Part 1: ICAO CNS / ATM Concept. M.-SPb .: NIIER OJSC, 1999, 206 p.

2. Automatic dependent surveillance - broadcasting. Information document, version 1.0 - M .: Gos NIIAS, 1998, 39 pp.

3. Copyright certificate No. 1596468, MKI N 04 B 7/26, 1990 (prototype).

Claims (3)

1. The method of radio communication with mobile objects, which consists in transmitting from a central station (CA) a block of information containing the data stored in it, receiving it on mobile objects (PO) and transmitting from a mobile object an information signal containing a confirmation of the receipt of a block of information from a CA and data from sensors of a moving object, delayed relative to the information block received from the central station, characterized in that code groups of the type of work, type request, are introduced into the information block from the central station data, the nominal operating frequency for the next exchange frame and the start time of the next frame, the data in the information signal from each of the moving objects is distributed over time intervals depending on the number determined by the code group of the type of work, starting from the time specified by the code group of the start time of the next frame, the mutual synchronization in time of the central station and moving objects is carried out using the time scale of the global navigation system, the frame duration T is determined and coming down from the purpose of the radio communication system, but no more T = (1 + Nn) τ + t for τ> mσ _t , where N is the number of software; n is the number of bits in the message with the software; t is the maximum total time of propagation of the radio signal along the line of the CA - PO - CA and double the duration of the message from the CA; σ _t is the relative standard error of the determination of the current time interval; τ is the duration of a single transmission of information; m is a coefficient (greater than unity), depending on the purpose of the radio communication system. 2. The method of radio communication with mobile objects according to claim 1, characterized in that the working frequency of radio communication for each mobile object is determined by the previous code group of the type of operation of the information block from the central station. 3. The method of radio communication with mobile objects according to claim 1, characterized in that according to the information signals of neighboring frames of each mobile object at the central station, one judges its condition and characteristics of the radio link.