RU2292119C2 - Method for exchanging messages and radio system for realization thereof - Google Patents

Abstract

FIELD: aviation radio communications of decameter spectrum, possible use for packet digital radio communications with TDMA-TDD access (multi-access with time division) in telecommunication networks of decameter spectrum (in particular for GlobaLink/HF system), when natural broadband interference and technical narrowband interference is present.

SUBSTANCE: in accordance to method, separate transmitting control channel is used for transferring bi-spectrally organized signals containing control information from base station, resulting in representation of primary signal (at physical level) in form of information structure of M elements, reflecting control message as a whole (bi-spectrally organized signal squitter) in form of two-dimensional image, elements of which represent 3 order spectrum counts of bi-spectrally organized signal.

EFFECT: individual transmitting control channel at base station and individual receiving control channel at client station allow improvement of guaranteed message delivery time, because within one frame up to 13 bi-spectrally organized signal squitters may be received.

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Description

The invention relates to aviation radio communication DKMV range and can be used for packet digital radio communication with TDMA-TDD access (multiple access with time sharing) in telecommunication radio networks DKMV range, in the presence of both broadband natural interference and narrowband technical interference.

Currently, telecommunication systems are built on the basis of a model for the interaction of open systems with a 7-level structure in accordance with ISO 7489.

A known method of transmitting messages [1] using a broadband signal based on a bispectrally organized signal (BOS), providing a fairly high noise immunity and the ability to work in conditions of noise of various nature. This method provides for the implementation of only the first (physical) level according to the 7-level model of ISO 7498, without a separate control channel being allocated. The concept and implementation of a special separate exchange of control information in this method are absent. This leads to a rather lengthy process of establishing a connection and requires a predetermined algorithm for coding and decoding in terms of the choice of frequencies, of which triplets (multiplets) are composed. The organized (programmed) structure of a multispectrally organized signal cannot be dynamically rebuilt based on the conditions of propagation of radio waves, which is especially important in the DKMV range, because there is no control information for such a restructuring in the process of conducting a communication session. This leads to suboptimal expenditures of the time resource, the lack of data on the passage of information from the transmitter to the receiver, and, ultimately, to an increase in the guaranteed delivery time of the user message.

A known method of exchanging data according to Specification ARINC 635, which consists in using the TDMA-TDD protocol [2], selected as a prototype. This specification defines the frame structure of the TDMA-TDD protocol for messaging and control information, including a slot containing broadcast control information from the base station (SPDU - squitter), outgoing message slots from the base station to the subscriber, incoming message slots from the subscriber stations to the base, as well as free access slots for registering new subscribers (subscriber stations to the base station). This specification provides for the exchange of data of both control and informational nature on one selected operating frequency of the DKMV range. At the same frequency, the base station receives free access slots for registering new subscribers.

The TDMA-TDD access protocol for the communication channel and control information is combined with frequency separation (FDMA) for the system as a whole. TDMA slots are dynamically assigned using a combination of reservation, polling, and random access requests.

This protocol works as follows. Each ground station is assigned several active frequencies. Work on each of the active frequencies is divided into time frames with 13 slots. The frame duration is 32 seconds, the slots are 2.46 seconds. The first slot of each frame is intended for transmission from the base station of the squitter. The remaining slots can be allocated either for transmission to the subscriber, or for transmission from a specific subscriber, or as random access slots for transmission from the subscriber for use by all subscribers in random access mode. The assignment of slots for the lines "to the subscriber" or "from the subscriber" for the current frame is carried out by the ground station and transmits this information in the squitter. In addition, each squitter contains an identifier and other active frequencies of the base station, as well as identifiers and active frequencies for two neighboring DKMV base stations, providing coverage of the common area. Squitters also contain receipts for all messages received from subscribers in the previous two frames, and channel utilization data.

The disadvantage of this protocol is that for registration in the system, it is necessary to search for an acceptable frequency by receiving several squitters at different frequencies with acceptable quality, then apply the free access mode to the connection in the corresponding slot allocated for this, and only on the next frame receive a new squitter , from the analysis of the information contained in which, it becomes clear whether the registration of this subscriber has occurred in the radio communication system at the selected frequency or not. Only after this is it possible to receive or transmit a user message in the time slot allocated for this purpose. As a consequence of this procedure, a large registration time in the system and, therefore, a large minimum guaranteed delivery time for a user message (from 90 to 120 s). In addition, with a small number of subscriber stations operating at a given fixed channel frequency, significant time losses occur due to a fixed frame structure (32 s), which is rigidly set by the first slot - squitter. The temporal structure of a TDMA protocol frame according to the ARINC 635-3 Specification is shown in FIG.

A device is known that implements a polyharmonic carrier RF signal [1], however, it carries out unidirectional transmission of a bispectrally organized signal from a transmitter through a communication line to a receiver in which triplets (primary carriers of useful information through a communication line of any physical nature) are converted (demodulated) sound waves, electromagnetic waves, infrared, etc.). In the specified device, there are no controls for the process of transmitting a message, which leads to suboptimal use of a temporary resource allocated for the delivery of information (user messages).

Also known is a radio data transmission system with time sharing [3], which consists of a base and a number of subscriber transceivers and corresponding antenna systems.

The main disadvantages of this radio system are the use of one operating frequency for receiving and transmitting both control and user information, and, as a result of this, the absence of communication at certain frequencies during certain periods of time (or poor communication quality with a large number of errors) due to ionospheric instability propagation of the RF signal, as well as the use of separate slots for receiving incoming control information and transmitting outgoing control information and, as a result, non-optimal use of a time resource (volume of user data / time slot).

The main technical problem to be solved by the group of the proposed inventions is to reduce the time of guaranteed delivery of a user message, increase noise immunity, and reduce the registration time of a subscriber station in a radio communication system.

The indicated technical result is achieved in that in a messaging method based on the use of time division multiple access protocol, in which each message exchange frame between the base station and subscriber stations contains an outgoing control slot for transmitting communication line management information SPDU-squitter, slots exchange of user information between base and subscriber stations, as well as free access slots for registering new incoming subscribers, and use Using the separation of the frequency resource for the radio system as a whole, the information contained in the said outgoing control slot is additionally transmitted over the course of each frame from the base station using a separate transmitting control channel in which the primary signal of the physical layer is formed in the form of an information structure of M elements, representing the control message as a whole in the form of a two-dimensional image, the elements of which are samples of the spectrum of the third order bispectrally organized nnogo signal, and a subscriber station in a reception control channel analyze the quality and content of the received control signal is formed on the receipt received information and transmitting it over the channel to the selected messaging for communication rate to the base station.

The specified technical result is achieved in that in a radio system for implementing a messaging method consisting of a base station and a number of subscriber radio stations exchanging messages in accordance with a time division multiple access protocol, the base station contains n receivers and n transmitters to ensure the implementation of the protocol on a separate frequency and an additional transmitting control channel, consisting of a series-connected decision block on triplet frequencies also connected to the interface with external user systems, a bispectrally organized signal modulator and a bispectrally organized signal transmitter, and the subscriber station, in addition to the main channel-forming equipment, including an antenna matching device and a transceiver connected to the interface with external user systems, additionally contains a receiver in series bispectrally organized signal with the corresponding antenna matching device, bi demodulator a spectrally organized signal and a decision block on triplet frequencies, which in turn is connected to a transceiver and an interface with external user systems, the antenna matching device of a bispectrally organized signal receiver being connected through a frequency separation device to a common antenna of a subscriber station.

Distinctive features of the proposed group of inventions is the use of a separate transmitting control channel for transmitting bispectrally organized biofeedback squitters containing control information from the base station, which is expressed in the representation of the primary signal (at the physical level) in the form of an information structure of M elements reflecting the control message as a whole in the form of a two-dimensional image, the elements of which are samples of the 3rd order spectrum of a bispectrally organized signal (BOS).

, где φ_f1, φ_f2, φ_f3 - фазы соответствующих ВЧ-колебаний частот f1, f2, f3, составляющих триплет, обуславливает высокую помехоустойчивость как фундаментальное свойство систем с полиспектрально организованным сигналом.The use as a carrier frequency for transmitting control information not of a single-mode (single-frequency), but of a specially organized three-mode (f1, f2, f3) signal with a given condition for phase relations, namely,

, where φ _f1 , φ _f2 , φ _f3 are the phases of the corresponding RF oscillations of the frequencies f1, f2, f3 that make up the triplet, which determines high noise immunity as a fundamental property of systems with a multispectrally organized signal.

Using a specially organized channel for transmitting a control message makes it possible to reduce the time of guaranteed delivery of a user message due to the fact that up to 13 biofeedback squitters can be sent and received accordingly.

The proposed radio data exchange system does not interfere with the operation of a traditional radio system that implements the ARINC 635-3 specification, but only harmoniously supplements it and improves the user characteristics of the radio system.

The temporal structure of a TDMA protocol frame according to the ARINC 635-3 Specification [2] is shown in FIG.

The proposed temporal structure of the frame and slots is shown in figure 2.

The structural diagram of a radio messaging system is shown in figure 3, where indicated: 1 - subscriber station; 2 - channel-forming messaging equipment; 3 - antenna matching device; 4 - transceiver; 5 - frequency separation device; 6 - receiving control channel; 7 - broadband antenna matching device; 8 - biofeedback receiver; 9 - biofeedback demodulator; 10 - decision block on triplet frequencies; 11 - interface with external user systems; 12 - base station; 13 - transmitting control channel; 14 - BOS transmitter; 15 - biofeedback modulator; 16 ₁ ... 16 _n - receivers with frequencies f1 ... fn; 17 ₁ ... 17 _n - transmitters with frequencies f1 ... fn.

The claimed messaging method is as follows. At the base station 12, in the decision block on the frequencies of triplets 10, a multispectral image is formed in the form of an array of triplets [3], which displays the control information received through the interface with external user systems 11. The generated image is fed to a modulator 15, in which it is converted to noise-like signal in the time domain. The converted signal through the biofeedback transmitter 14 and the corresponding antenna is radiated into space. The signal received by the BOS subscriber station 1 passes through the frequency separation device 5 to the receiving control channel 6 and, after demodulation, enters a similar decision block on the frequencies of the triplets 10. After analyzing the received control information, the subscriber station transmits to the base station via the traditional messaging channel 2 own message and receipt for BOS-squitter to confirm the establishment of two-way communication and receive control information from the base station without errors.

A radio system that implements the proposed method of messaging (figure 3), consists of a base station 12 and subscriber stations 1.

The base station includes n receivers 16 ₁ -16 _n and n transmitters 17 ₁ -17 _n , (n = 3 ... 6), which are connected to terminal systems via an interface with external user systems 11. The decision block on the frequencies of the triplets 10, the biofeedback modulator 15, and the biofeedback transmitter 14 form a transmitting control channel 13, which in turn is connected to the corresponding antenna. The transmitting control channel 13 through the decision block on the frequencies of triplets 10 is connected to the interface with external user systems 11.

The receivers 16 ₁ -16 _n and the transmitters 17 ₁ -17 _n , operating at frequencies f1 ... fn, are also connected to the respective receiving and transmitting antennas.

The subscriber station 1 includes a channel-forming messaging apparatus 2, an interface with external airborne systems 11, a frequency separation device 5, and a control receiving channel 6. The channel-forming messaging apparatus 2 includes an antenna matching device 3 and a transceiver 4 operating on one of the frequencies f1 ... fn. The receiving control channel 6 includes: a broadband antenna matching device 7, a biofeedback receiver 8, a biofeedback demodulator 9 and a decision-making unit for triplet frequencies 10. The channelization equipment for messaging 2 and the receiving control channel 6 are connected via a frequency separation device 5 to the antenna of the subscriber station. Depending on the quality of reception of the triplets of the BOS squitter, in the decision block on the frequencies of triplets 10, data is generated on the array of frequencies at which it is advisable to exchange messages between base 12 and subscriber stations 1.

As rightly noted in [1], a bispectrally organized signal is characterized by a large noise immunity and information transfer rate as a whole due to the simultaneous parallel coding of a large data array, therefore, the probability of delivering control information via the control channel is always higher than the probability of delivering the actual messages via the messaging channel.

The proposed method and system is a continuation of the use in RF communication channels of both the traditionally single-frequency sinusoidal carrier of a useful signal in the data exchange channel and the use of the "multi-frequency" carrier as a combination of several frequencies connected by a predetermined ratio of the parameters of these carriers (in our case, a bispectrally organized signal), to improve such a characteristic of the propagation of radio waves as reducing the ratio "Signal / Noise", at which it is still possible to extract useful second information from a mixture of "signal + noise".

The system that implements the proposed method is constructed in such a way that an additional radio control channel is introduced with its own protocol of interaction with the subscriber (s) based on the use of a bispectrally organized signal, which allows to reduce the registration time, reduce the guaranteed time of data delivery in the system, and increase the number of subscribers in one radio channel. Analysis of the passage of components of a bispectrally organized signal in the decision block on triplet frequencies allows you to optimally select and, if necessary, change the frequency values at which messages are exchanged in the radio channel for exchanging user messages. The use of a bispectrally organized signal in the control channel improves the noise immunity, range and reliability of both the control channel and the entire system as a whole by achieving the required quality by selecting the frequency of the data exchange channel based on the analysis of the passage of the bispectral signal in the control channel.

Frames of the proposed modified protocol for the messaging channel and for the control channel are shown in Fig.2. It should be noted that biofeedback squitters are emitted by the base station simultaneously with the exchange of information on single-frequency channels.

The system operates as follows, implementing the claimed method. At base station 12, in the decision block on the frequencies of triplets 10, sets F1, F2, F3 are created that obey the conditions of a bispectrally organized signal, then the entire array is transmitted to the biofeedback modulator, in which the triplet array is modulated [5]. Then, the accumulated modulated array is converted into a noise-like signal and enters the BOC 14 transmitter, amplified and transmitted to the antenna of the base station. After the bispectrally organized signal appeared on the air during the radiation, it begins to be received via the control information receiving channel 6 by the switched on (both registered and unregistered) subscriber stations 1 located in the coverage area of this base station. In this case, the biofeedback squitter via the antenna of the subscriber station, the frequency separation device 5, the broadband antenna matching device 7, the biofeedback receiver 8 gets to the biofeedback 9 demodulator, in which the bispectrally organized array is demodulated, and the semantic information of the messaging channel control falls into the reception decisions on the frequencies of triplets 10, in which control information is analyzed and control signals are generated by which the parameters of the transceiver are controlled 4 (including the carrier RF frequency and information exchange rate) of the messaging channel and sending data via an interface with external systems of the user 11 to other systems and subsystems of the user of the subscriber station 1.

After the decision on the value of the carrier RF frequency at which it is advisable to communicate is made in the decision block on the frequencies of triplets 10 of the subscriber station 1, a message slot is formed for the base station, and in the time interval defined in the control information transmitted over the channel control, there is a radiation of a modulated single-frequency signal of the subscriber station 1, which is received at the receiver 16 ₁ -16 _n , the base station 12 at one of the frequencies f ₁ ... f _n . The base station 12 generates and transmits a response message at the same frequency that it receives and emits it in the allotted time interval in the frame (in Fig. 1. this is slot No. 1, and slot No. 13, labeled UL). According to the information received from the base station, the composition of the triplets can be dynamically transformed, on the basis of which the biofeedback squitter emitted by the base station is built.

In the data transmitted from the subscriber station, a receipt is placed on the propagation quality of the components of the high-frequency array of frequencies that satisfy the criteria of a bispectrally organized signal.

In the decision block on the frequencies of triplets 10 there is always a dynamically changing system table of frequencies (updated with new values of operating frequencies based on the analysis of the passage through the air of the RF carrier of the actual single-frequency SPDU squitter and the RF component of the triplets of the BOS squitter), which can be used to select a new one messaging frequencies when signal quality deteriorates at the current frequency of the messaging channel.

The interface with external user systems 11 both in the subscriber station 1 and in the base station 12 is intended for electrical connection and pairing of signals with external user systems. The protocol and the bus through which this interaction takes place do not play a fundamental role for the proposed technical solution, but it is optimal to use the 7-level model of interaction between open ISO / OSI systems (Fig. 3).

As part of the control channel, a broadband three-channel transceiver is implemented (three transmitters and three receivers with a special system for synchronizing and retaining phase relations between the components of triplets that implement the theoretical relationships of bispectrally organized signals described in detail in the analogue of the proposed system, namely, in RU 2097924 C1).

Computing equipment that interfaces with external user systems and a decision block on triplet frequencies is represented by Pentium-3 computers with built-in 12-bit ADC / DAC (L-1210 and L-305 boards with quantization frequencies up to 100 and 300 kHz, respectively ) ADC / DAC boards are equipped with devices for synchronizing their operation with highly stable master oscillators (stabilized crystal oscillator of the frequency meter Ch3-34A and quantum standard Ch1-69). The subunits of the low-pass filter that are part of the BOS modem on the transmitting and receiving sides are the low-pass filter of Bessel or Butterworth (8th order, cut-off frequencies 20 Hz, 2.5 kHz, 20 kHz, 50 kHz) with an adjustable transmission coefficient in the passband (0 dB - 66 dB).

The equipment of subscriber stations consists of a transceiver with a single-frequency channel for exchanging user messages, which is implemented according to the requirements of Arinc 753 and Arinc 635, and a receiving control channel similar to the device described in [6].

Industrial, commercially available samples are, for example, products from Collins (USA) - the HFS-900D system; ХК-516, ХК-2000 by Rohde & Schwarz (Germany), which are widely used in the globaLink / HF industrial-operated global communication system.

The transmitting control channel and the receiving control channel of the proposed radio system are broadband equipment for transmitting and receiving DKMV range (similar to 3-channel equipment with phase synchronization) with stringent requirements for amplitude-phase conversion in the channels of the passage of triplets and extremely linear frequency response of the channels [6].

The decision block is a computing module based on a 1B578 type microprocessor (79RC32364 by IDT company with a clock frequency of 133 MHz), with the corresponding software that implements ALE procedures (Automatic link establishment - automatic establishment of a communication channel according to the FED-STD 1045A standard).

Successful tests of the principles of communication through a bispectrally-organized signal were carried out, and a number of technical devices were developed at the level of experimental models.

Literature:

1. RU 2097924 C1, MKI ⁶ H 04 V 7/00, 11/00.

2. ARINC Specification 635-3 "HF Data Line Protocol". (Prototype method)

3. JP 3235041 B2, MKI ⁷ H 04 J 3/00. (Prototype device)

4. Bochkov G.N., Gorokhov K.V. A method for synthesizing bispectrally organized signals // Letters in ZhTF. 1995.V.21. B.16. S.27-32.

5. Bochkov G.N., Gorokhov K.V. Bispectrally organized signals for parallel information transmission systems with correction of amplitude-phase distortions. Izv. Universities. Radiophysics, 1997.V.30. No. 11.

6. Andriyanov A.V., Putin M.V., Voitkevich K.L., Rezvov A.V. 2004 DKMV Three-Channel Digital Transceiver Station. 14th Int. Crimean Conference "Microwave & Telecommunication Technology" (CriMiCo'2004). September 13-17, Sevastopol, Crimea, Ukraine.

Claims (2)

1. A method of exchanging messages based on the use of time-division multiple access protocol, in which each message exchange frame between the base station and subscriber stations contains an outgoing control slot for transmitting communication line management information, user information exchange slots between the base and subscriber stations, as well as free access slots for registering new incoming subscribers, and using frequency resource sharing for the radio system as a whole m, characterized in that the information contained in the aforementioned outgoing control slot is additionally transmitted repeatedly from the base station during each frame using a separate transmitting control channel, in which the primary signal of the physical layer is formed in the form of an information structure of M elements representing a control message as a whole in the form of a two-dimensional image, the elements of which are samples of a third-order spectrum of a bispectrally organized signal, and at a subscriber station in The receiver control channel analyzes the quality and content of the received control signal, generates a receipt for the received information and transmits it via the messaging channel at the frequency selected for communication to the base station. 2. The radio system for implementing the messaging method according to claim 1, consisting of a base station and a number of subscriber radio stations exchanging messages in accordance with a time division multiple access protocol, characterized in that the base station contains n receivers and n transmitters to ensure implementation mentioned protocol at a separate frequency and an additional transmitting control channel, consisting of series-connected decision block on the frequencies of triplets, also connected to interface with external user systems, a bispectrally organized signal modulator and a bispectrally organized signal transmitter, and the subscriber station, in addition to the main channel-forming equipment, including an antenna matching device and a transceiver connected to the interface with external user systems, additionally contains a bispectrally organized signal receiver in series with appropriate broadband antenna matching device, bispectral demodulator about an organized signal and a decision-making unit on triplet frequencies, which, in turn, is connected to a transceiver and an interface with external user systems, and the broadband antenna matching device of a bispectrally organized signal receiver is connected through a frequency separation device to the antenna of the subscriber station.

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