RU2796968C1 - Device for transmitting information in a multipath channel of tropospheric microwave radio communication - Google Patents

Abstract

FIELD: radio communications.

SUBSTANCE: transmission and receiving information in tropospheric communication systems. The device contains a transmitter and a receiver, while the transmitter additionally includes an encoder, a QPSK manipulator and a power amplifier, and the receiver additionally includes a receiving multipath tropospheric communication antenna, a signal spectrum preprocessing unit, a QPSK demanipulator and a decoder.

EFFECT: simplifying the design of the device, increasing the noise immunity and increasing the reliability of its operation.

1 cl, 1 dwg

Description

The device belongs to the field of radio communications and can be used to transmit and receive information in tropospheric communication systems.

Known "Transportable tropospheric station" [1], containing an antenna, a transceiver, a modem, time multiplexing equipment, a reference oscillator unit, a synchronization unit, an antenna control unit, a modem control unit, a station control panel, connecting lines for issuing / receiving digital paths to consumers.

The main disadvantages of this station are: low information transfer rate up to 2048 Kbps and the need to use a navigation system to synchronize the reference oscillator.

Known as "Multi-carrier modem" [2]. This device contains on the transmitting side a serial-to-parallel converter, a generator of complex values of transmitted symbols with relative phase shift keying, an inverse discrete Fourier transform, a parallel-to-serial converter, a guard interval addition unit, a digital-to-analog converter and an amplitude modulator, and on the receiving side it contains an analog-to-digital converter, a synchronization block, a guard interval removal block, a serial-to-parallel converter, a discrete Fourier transform block, a relative phase shift keying symbol demodulation block, a parallel-to-serial converter, and an amplitude demodulator.

The main disadvantages of this device are the complexity of implementation and the relatively low noise immunity of the transmitted information.

The closest technical solution is the "Modem for multi-carrier signals" [3], containing a transmission path, including a modulator consisting of a serial-to-parallel converter unit, a generator of complex values of transmitted symbols with relative phase shift keying, an inverse discrete Fourier transform unit, the first and second digital-to-analog converters, the first and second multipliers, the phase shifter, the radio frequency signal generator and the adder, as well as the receiving path, which includes a demodulator consisting of an input matching unit, the first and second multipliers, the phase shifter, the radio frequency signal generator, the first and the second filters, the first and second analog-to-digital converters, the direct discrete Fourier transform unit, the detector unit and the parallel-to-serial conversion unit.

The main disadvantages of this device are the complexity of implementation, the relatively low noise immunity of information transmission and the reliability of its operation.

The purpose of this invention is to simplify the design of the device, improve noise immunity and increase the reliability of its operation.

This goal is achieved by the proposed "Information transmission device in a multipath channel of tropospheric microwave radio communication", containing a transmitter and a receiver, while the transmitter includes a serial-to-parallel converter unit (demultiplexer), an inverse discrete Fourier transform unit, a digital-to-analog converter and a tropospheric communication transmitting antenna, and the receiver includes an analog-to-digital converter, a direct discrete Fourier transform unit and a parallel-to-serial conversion unit (multiplexer), while an encoder, a QPSK manipulator and a power amplifier are additionally included in the transmitter, and the receiver additionally, a TRS receiving multibeam antenna, a signal spectrum preprocessing unit, a QPSK demanipulator, and a decoder were introduced.

The scheme of the proposed device is shown in the drawing, which indicates:

1 - transmitter;

2 - block of serial-parallel conversion (demultiplexer);

3 - encoder;

4 - QPSK manipulator;

5 - block inverse discrete Fourier transform;

6 - digital-to-analog converter;

7 - power amplifier;

8 - transmitting antenna for tropospheric communication;

9 - receiving multibeam antenna for tropospheric communication;

10 - receiver;

11 - block for preliminary processing of signal spectra;

12 - analog-to-digital converter;

13 - block direct discrete Fourier transform;

14 - QPSK demanipulator;

15 - decoder;

16 - block parallel-to-serial conversion (multiplexer).

As shown in the drawing, the connection of the constituent elements in the proposed device is carried out as follows: in the transmitter 1, the information source is connected to the input of the serial-to-parallel conversion unit (demultiplexer) 2, the parallel outputs of which are connected to the parallel inputs of the encoder (3), the parallel outputs of which connected to the parallel inputs of the QPSK manipulator (4), the parallel outputs of which are connected to the parallel inputs of the block (5) of the inverse discrete Fourier transform, the output of which is connected to the input of the digital-to-analog converter (6), the output of which is connected to the input of the power amplifier (7), the output of which is connected to the input of the transmitting antenna of tropospheric communication (8), and in the receiver (10) the outputs of the receiving multibeam antenna of tropospheric communication (9) are connected to the inputs of the signal spectrum pre-processing unit (11), the output of which is connected to the input of the analog-to-digital converter ( 12), the output of which is connected to the input of the block (13) of the direct discrete Fourier transform, the parallel outputs of which are connected to the parallel inputs of the QPSK demanipulator (14), the parallel outputs of which are connected to the parallel inputs of the decoder (15), the parallel outputs of which are connected to the parallel inputs of the block (16) parallel-to-serial conversion (multiplexer), the output of which is connected to the user information.

The purpose of the constituent elements of the proposed "Devices for transmitting information in a multipath channel of tropospheric microwave radio communication" is clear from their name. All these are standard elements and functionally complete units of computing and switching technology, mass-produced by the industry. The proposed device, which consists of standard equipment, does not require additional technical creativity, which is especially important in mass production. Therefore, the proposed device satisfies the criterion of industrial applicability.

The operation algorithm of the proposed device is based on the OFDM orthogonal frequency multiplexing technology, which was previously developed and successfully used to combat interference in multipath reception. With OFDM, a serial digital stream is converted into a large number of parallel streams (substreams), each of which is transmitted on a separate carrier. Technically, the OFDM method is implemented by performing an inverse (inverse) Discrete Fourier Transform (FFT) in the transmit path modulator and a Direct Discrete Fourier Transform (DFT) in the receive path demodulator. OFDM channel coding of substreams involves the use of Forward Error Correction (FEC), which is used to correct glitches and errors in data transmission. Due to the transmission of redundant service information, it is possible to recover lost data, which is especially important in multipath conditions.

The proposed device, in comparison with the prototype, contains new elements, namely, a demultiplexer (2), an encoder (3), a QPSK manipulator (4), an inverse discrete Fourier transform unit (5), a power amplifier (7), a receiving multibeam tropospheric communication antenna (9 ), signal spectrum preprocessing block (11), direct discrete Fourier transform block (13), QPSK demanipulator (14), decoder (15) and multiplexer (16), i.e. meets the requirement of novelty.

The operation of the proposed device is as follows:

On the transmitting side, the demultiplexer (2) converts the sequence of information coming to its input in digital form into a sequence of n parallel OFDM streams, the transmission rate of each of which is n times less than the rate of the primary digital stream.

Encoder (3) encodes each of the n OFDM streams received at its input.

The QPSK manipulator (4) performs quadrature-phase keying (digital processing) of each of the COFDM streams received at its input.

Block (5) of the inverse discrete Fourier transform converts n parallel COFDM signals into a serial stream of digital information.

The block (6) of digital-to-analog conversion converts the sequence of digital information received at its input into an analog one to be transmitted over the air.

The power amplifier (7) amplifies the analog signal received at its input and outputs it to the input of the tropospheric communication transmitting antenna (8).

On the receiving side, the receiving multi-beam tropospheric communication antenna (9) receives the multi-beam signals arriving at its input, formed from one transmitted by its reflection from troposphere inhomogeneities, and transmits them to the block (11) for preliminary processing of the signal spectra.

Block (11) for preliminary processing of signal spectra selects the beam with the largest value of the input signal and outputs it to the input of block (12) for analog-to-digital conversion.

The analog-to-digital conversion unit (12) converts the analog signal received at its input into a digital one and outputs it to the input of the unit (13) of the direct discrete Fourier transform.

In block (13) of the direct discrete Fourier transform, the serial signal is converted into n parallel COFDMs.

In the QPSK demanipulator (14), demanipulation (digital processing) of the signals received at its input is carried out, during which the original COFDM signals are extracted from the manipulated signals.

In the decoder (15), each of the n COFDM streams is decoded.

In block (16) parallel-to-serial conversion (multiplexer), n parallel OFDM streams arriving at its input are converted into a serial stream, the transmission rate of which is n times greater than the rate of each of the n parallel digital streams.

The serial digital stream from the output of the block (16) parallel-to-serial conversion (multiplexer) is supplied to the information user.

Due to the fact that the proposed device additionally includes a serial-parallel conversion unit (demultiplexer) (2), an encoder (3), a QPSK manipulator (4), an inverse discrete Fourier transform unit (5), a power amplifier (7), a receiving multipath tropospheric communication antenna (9), signal spectrum preprocessing unit (11), direct discrete Fourier transform unit (13), QPSK demanipulator (14), decoder (15) and parallel-to-serial conversion unit (multiplexer) (16), with appropriate the scheme of their connection between themselves and with other elements of the device, in the transmission-reception path of high-speed digital information, the demultiplexing of the transmitted and multiplexing of the received OFDM signal, encoding of the transmitted and decoding of the received COFDM signal, quadrature-phase keying on transmission and de-manipulation on reception, amplification of a more stable signal transmitted on the air, reception of a multipath signal with the choice of a beam with the highest value of a more stable signal at the reception, the noise immunity and reliability of the device operation are significantly increased, taking into account the simplicity of its design.

This device differs significantly from those known in the art. The claimed device does not explicitly follow from the prior art and has an inventive step. This allows us to conclude that the device meets the “significant differences” criterion.

Therefore, we can conclude that the goal set for this invention - simplifying the design of the device for transmitting information in a multipath channel of tropospheric microwave radio communication, increasing noise immunity and increasing the reliability of its operation - has been achieved.

The proposed device can be widely used in the construction of widely branched multi-channel systems and communication networks.

Information sources

1. Patent of the Russian Federation No. 2715554 for the invention "Transportable tropospheric station", IPC H04V 7/22, 2020, Bull. 7.

2. Patent of the Russian Federation No. 27766 for a utility model "Modem with multiple carriers", IPC H04L 27/00, H04B 7/00, 2003, Bull. 4.

3. RF patent No. 148374 for a utility model "Modem for multi-carrier signals", IPC G06F 17/3, H04L 27/00, 2014, Bull. 34.

Additional sources of information

1. https://ru.wikipedia.org/wiki/OFDM.

2. https://ru.wikipedia.org/wiki/COFDM.

3. https://en.wikipedia.org/wiki/Orthogonal_frequency-divisionmultiplexing.

4. https://infopedia.su/17x373a.html.

5. https://russianblogs.com/article/5904195186.

6. https://edu.tusur.ru/publications/9528/download.

Claims (1)

A device for transmitting information in a multipath channel of tropospheric microwave radio communication, comprising a transmitter and a receiver, wherein the transmitter includes a serial-parallel conversion unit, an inverse discrete Fourier transform unit, a digital-to-analog converter and a tropospheric communication transmitting antenna, and the receiver includes analog - a digital converter, a direct discrete Fourier transform unit and a parallel-to-serial conversion unit, characterized in that an encoder, a QPSK manipulator and a power amplifier are additionally included in the transmitter, and a receiving multibeam tropospheric communication antenna, a signal spectrum preprocessing unit are additionally introduced into the receiver , a QPSK demanipulator and a decoder, while in the transmitter the information source is connected to the input of the serial-parallel conversion / demultiplexer unit, the parallel outputs of which are connected to the parallel inputs of the encoder, the parallel outputs of which are connected to the parallel inputs of the QPSK manipulator, the parallel outputs of which are connected to the parallel inputs of the block inverse discrete Fourier transform, the output of which is connected to the input of a digital-to-analogue converter, the output of which is connected to the input of a power amplifier, the output of which is connected to the input of the transmitting antenna of tropospheric communication, and in the receiver, the outputs of the multibeam antenna of tropospheric communication are connected to the inputs of the pre-processing block of signal spectra, the output of which is connected to the input of an analog-to-digital converter, the output of which is connected to the input of the direct discrete Fourier transform block, the parallel outputs of which are connected to the parallel inputs of the QPSK demanipulator, the parallel outputs of which are connected to the parallel inputs of the decoder, the parallel outputs of which are connected to the parallel inputs of the block in parallel- serial conversion/multiplexer, the output of which is connected to the user information.

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