JP2005064846A - Interference eliminator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an interference eliminator which is capable of always eliminating an interference with high precision without being affected by the shake of a transmission/reception antenna and the variance of peripheral electric wave environments. <P>SOLUTION: The interference eliminator which eliminates an interference signal from the reception signal of a desired wave including the interference signal is provided with: a means of inputting an interference source signal which is not affected by the variance of an radio wave environment; a quadrature demodulation means for performing the quadrature demodulation of the reception signal by using the interference source signal; a low pass filter means for filtering the low band of an output signal of the quadrature demodulation means to extract only the variance element of the interference signal; and a quadrature modulation means for performing the quadrature modulation of the interference source signal on the basis of the output of the low pass filter. The interference eliminator eliminates the interference signal from the reception signal on the basis of an output of the quadrature modulation means. The interference eliminator is also provided with an inverter which is arranged between the low pass filter means and the quadrature modulation means and converts the output of the low pass filter means to an opposite phase, and an addition means for adding the output of the quadrature modulation means and the reception signal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a technique effective for eliminating interference of radio waves between business communication radio stations.

  Conventionally, in order to eliminate interference that can be applied to any transmission method, a method has been used in which the amplitude and phase of a signal of an interference source are fixedly adjusted in advance and fixedly subtracted. For example, Patent Document 1 relates to an inter-transmission / reception interference removal apparatus that removes interference with a reception signal due to leakage of a transmission signal, but Patent Document 1 discloses that a transmission signal from a transmitter is transmitted from a first line. A transmitter between a transmitter and a shared circulator in a wireless device that adds a received signal from the antenna to a receiver through a shared circulator in addition to an antenna via a shared circulator Connect a circulator for connection, connect a directional coupler on the receiver side between the receiver and the shared circulator, and connect an amplifier and phase shift between the circulator for transmitter connection and the directional coupler on the receiver side. The difference between the path length from the transmitter connecting circulator via the first line and the second line and the path length of the third line is As λ / 2 (λ = wavelength) or an odd multiple thereof, configured to cancel the leakage transmission signal component is described.

JP-A-9-116459

  For this reason, conventionally, it has not been possible to cope with amplitude / phase fluctuations due to fluctuations in the transmitting / receiving antennas and changes in the surrounding conditions, and it has been difficult to always perform high-precision interference removal. For this reason, there has been no other way but to deal with such that the frequency arrangement does not cause interference.

  The present invention has been made in view of these problems, and an object of the present invention is to provide an interference eliminator capable of always removing interference with high accuracy without being affected by fluctuations in the transmitting / receiving antenna and fluctuations in the surrounding radio wave environment. It is to provide.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  In the present invention, the amplitude and phase of the interference signal included in the received signal with amplitude and phase fluctuations due to the fluctuation of the transmitting / receiving antenna and the surrounding radio wave environment are extracted using the signal of the interference source, and the interference signal is based on the extracted signal. The interference cancellation signal having the same amplitude and the opposite phase is dynamically generated, and the generated interference cancellation signal is combined with the received signal to remove the interference.

  That is, the present invention is an interference removal apparatus for removing an interference signal from a received signal of a desired wave in which interference signals are mixed, and includes an interference source signal input means that is not affected by a radio wave environment, and the interference source signal. Orthogonal demodulation means for orthogonally demodulating the received signal; low-pass filter means for low-pass filtering the output signal of the orthogonal demodulation means to extract only the fluctuation elements of the interference signal; and the interference source based on the output of the low-pass filter means Orthogonal modulation means for orthogonally modulating the signal, and removing the interference signal from the received signal based on the output of the orthogonal modulation means.

  An inverter disposed between the low-pass filter means and the quadrature modulation means, for converting the output of the low-pass filter means into a reverse phase; and an adding means for adding the output of the quadrature modulation means and the received signal. .

  The present invention also provides an interference removal apparatus for removing a plurality of interference signals from a received signal of a desired wave in which a plurality of interference waves are mixed, and a plurality of interference source signal input means that are not affected by radio wave environment, A plurality of orthogonal demodulation means for orthogonally demodulating the received signal by each interference source signal for each of the plurality of interference source signals, and low-pass filtering the output signals of the plurality of orthogonal demodulation means for each of the plurality of interference signals A plurality of low-pass filter means for extracting only the fluctuation elements; and a plurality of orthogonal modulation means for orthogonally modulating the plurality of interference source signals based on the outputs of the plurality of low-pass filter means. Based on this, the plurality of interference signals are removed from the received signal.

  A plurality of inverters arranged between the plurality of low-pass filter means and the plurality of quadrature modulation means, respectively, for converting the outputs of the plurality of low-pass filter means into opposite phases; and the outputs of the plurality of quadrature modulation means; Adding means for adding the received signal;

  The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.

  According to the present invention, it is possible to always remove interference with high accuracy without being affected by fluctuations in the transmitting / receiving antenna and fluctuations in the surrounding radio wave environment. Therefore, it is possible to arrange frequencies with higher density than in the past, and to use radio waves more effectively.

  Hereinafter, embodiments of the invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments of the invention, and the repetitive description thereof is omitted.

FIG. 1 is a diagram showing a radio station equipped with an interference cancellation apparatus according to an embodiment of the present invention. Only radio station 0 is equipped with an interference cancellation apparatus. 0 interference wave of the angular frequency omega ₀ of the desired wave cos angular frequency radio station 0,1～3 for receiving (omega ₀ t) from interfering the reception of the radio station 0 ω ₁ ~ω _n from the radio station 4 It is a communication radio base station k (k = 1 to n) that transmits cos (ω _k t) (k = 1 to n).

A radio station 0 shown in FIG. 1 includes a transmission / reception antenna 6 that transmits and receives radio waves, a transmission device (Tx) 7 that outputs a transmission signal, and an interference removal device that removes an interference signal included in a reception signal received by the transmission / reception antenna 6. 5, a reception device (Rx) 8 that performs reception processing on the reception signal after removal of the interference signal, and a transmission signal of the transmission device (Tx) 7 is supplied to the transmission / reception antenna 6 and the reception signal r (t) is supplied to the interference cancellation device 5 is configured with a switch 9 that outputs to 5. The interference removal apparatus 5 is configured to receive transmission signals 8cos (ω _k t) (k = 1 to n) output from the transmission apparatuses (Tx) 12, 22, and 32 of the other radio stations 1 to 3. ing. In the radio station 0, the desired wave cos (ω ₀ t) from the radio station 4 and the interference wave cos (ω _k t) (k = 1 to n) transmitted from the other radio stations 1 to 3 are transmitted and received by the transmission / reception antenna 6. Received at. Radio stations 1 to 3 transmit / receive antennas 15, 25 and 35, transmission devices (Tx) 12, 22, and 32, reception devices (Rx) 13, 23, and 33, and transmission devices (Tx) 12, 22, and 32, respectively. Switches 14, 24, and 34 that supply signals to the transmission / reception antennas 15, 25, and 35 and output received signals to the receivers (Rx) 13, 23, and 33 are provided.

  The signal r (t) received at radio station 0 is

It is represented by Here, one item is a signal obtained by receiving the desired wave cos (ω ₀ t) of the radio station 4 at the radio station 0, and the second and subsequent items are interference waves cos (ω _k t) (k = 1 to n) represents a signal received by the radio station 0.

The interference cancellation apparatus 5 receives the reception signal r (t) of the wireless station 0 and the transmission signal 8cos (ω _k t) (k = 1 to n) of the wireless stations 1 to 3. From the interference canceller 5, a signal a ₀ cos (ω ₀ t−θ ₀ ) from which two items of the received signal of the radio station 0 are removed is output.

FIG. 2 shows a schematic configuration of the interference canceling apparatus according to the embodiment of the present invention. The interference cancellation apparatus according to the embodiment of the present invention shown in FIG. 2 is configured to include interference cancellation blocks 51 to 53 corresponding to nearby radio stations 1 to 3. A transmission signal 8cos (ω _k t) (k = 1 to n) that is not affected by the radio wave environment is input to the interference removal blocks 51 to 53 from the neighboring wireless stations 1 to 3. Yes. Also, the received signal r (t) received by the radio station 0 is input from the interference canceller input 50, and this received signal r (t) is supplied to each interference cancel block 51 to 53 and the adder (synthesizer) 54. Is done.

Each of the interference cancellation blocks 51 to 53 includes input means 11, 21, and 31 to which the transmission signal 8 cos (ω _k t) (k = 1 to n) output from the corresponding wireless station is input. .

For example, the interference removal block 51 includes a hybrid 511 that distributes the input transmission signal 8cos (ω ₁ t) to the in-phase component and the quadrature component. The in-phase component distributed by the hybrid 511 is distributed to the multipliers 512 and 518, and the quadrature component is distributed to the multipliers 513 and 519. Further, the received signal r (t) supplied from the interference canceller input 50 is distributed to the multiplier 512 and the multiplier 513. Thus, the hybrid 511, the multiplier 512, and the multiplier 513 constitute an orthogonal demodulator.

  The multiplication output of the multiplier 512 is input to the LPF 514, and only the fluctuation component of the interference wave is extracted by the LPF 514 and input to the inverse circuit 516. The fluctuation element of the interference wave converted into the reverse phase by the inverse circuit 516 is input to the multiplier 518. A multiplication output of the output of the inverse circuit 516 and the in-phase component distributed by the hybrid 511 is output to the adder 54.

  Similarly, the multiplication output of the multiplier 513 to which the distributed received signal r (t) and the quadrature component distributed by the hybrid 511 are input is input to the LPF 515, and only the fluctuation component of the interference wave is extracted by the LPF 515. , And is input to the inverse circuit 517. The fluctuation element of the interference wave converted into the reverse phase by the inverse circuit 517 is input to the multiplier 519. A product output of the output of the inverse circuit 517 and the orthogonal component distributed by the hybrid 511 is output to the adder 54. As described above, the hybrid 511, the multiplier 518, and the multiplier 519 constitute an orthogonal modulator.

The other interference cancellation blocks 52 and 53 are also different in the transmission signal 8cos (ω _k t) (k = 2 to n) input from the input means 21 and 31, and the basic configuration is the same as the interference cancellation block 51. is there.

  The operation of this embodiment will be described below. The reception signal r (t) of the radio station 0 input from the interference canceller input 50 is distributed to the combiner 54 and also to the interference cancel blocks 51 to 53.

The reception signal r (t) of the radio station 0 distributed to the interference cancellation block 51 is the in-phase component 2cos (ω ₁ t) and quadrature component of the transmission signal 8cos (ω ₁ t) of the radio station 1 distributed by the hybrid 511 − Multiply by 2sin (ω ₁ t) by multipliers 512 and 513, respectively. The outputs of multipliers 512 and 513 are respectively
r (t) cos (ω ₁ t), -r (t) sin (ω ₁ t)
However, by passing LPFs 514 and 515 having a bandwidth sufficiently narrower than the frequency interval of each radio station, the outputs of LPFs 514 and 515 are respectively
(1/2) a ₁ cos (θ ₁ ),-(1/2) a ₁ sin (θ ₁ )
It becomes. By passing these through the inverse circuits 516 and 517
-(1/2) a ₁ cos (θ ₁ ), (1/2) a ₁ sin (θ ₁ )
Get. The outputs of these inverse circuits 516 and 517 are the in-phase component 2cos (ω ₁ t) and quadrature component −2sin (ω ₁ t) obtained by distributing the transmission signal 8cos (ω ₁ t) of the radio station 1 by the hybrid 511. Multiplication is performed by multipliers 518 and 519, respectively. The outputs of multipliers 518 and 519 are respectively
-a ₁ cos (θ ₁ ) cos (ω ₁ t), -a ₁ sin (θ ₁ ) sin (ω ₁ t)
It becomes. By adding these with the adder 54
-a ₁ cos (ω ₁ t- θ ₁ )
Get. Similarly, from the interference cancellation block 52,
-a ₂ cos (ω ₂ t- θ ₂ )
From the interference removal block 53
-a _n cos (ω _n t- θ _n )
Get. When the outputs of all the interference cancellation blocks 51 to 53 are added by the adder 54,

Get. Since the signal r (t) received by the radio station 0 is also input to the adder 54, the transmission signals of the radio stations 1 to 3 are removed from the output after all.
a ₀ cos (ω ₀ t- θ ₀ )
Is obtained. Here, for simplicity, the signal of the interference source is indicated by cos. However, by using a carrier wave or a reference signal having no amplitude variation, the modulation content of the interference source is changed to an FM signal, an AM signal, an RZ-SSB signal, The generality of any PSK signal, QAM signal, OFDM signal, etc. is not lost.

As described above, in the interference cancellation device 5 according to the embodiment of the present invention, first, the hybrids 511, 521, and 531 of the interference cancellation blocks 51 to 53 and the multipliers 512, 513, 522, 523, 532, and 533 transmit. The received signal r (t) is orthogonally demodulated by the signal 8cos (ω _k t) (k = 1 to n).

Next, only the fluctuation component of the radio wave is extracted from the orthogonally demodulated received signals by the LPFs 514, 515, 524, 525, 534, and 535 of the interference removal blocks 51 to 53. The fluctuation elements taken out by the LPFs 514, 515, 524, 525, 534, and 535 are converted into anti-phase by inverse circuits 516, 517, 526, 527, 536, and 537, and then the corresponding multipliers 518 and 519, respectively. 528, 529, 538, and 539 are input and quadrature modulated by the transmission signal 8cos (ω _k t) (k = 1 to n) to reproduce a signal having a phase opposite to that of the interference signal including a radio wave variation element. The reproduced signal having a phase opposite to that of the interference signal is added to the received signal r (t) by the adder 54, and only the received signal a ₀ cos (ω ₀ t−θ ₀ ) from the wireless station 4 is extracted.

As described above, in each of the interference removal blocks 51 to 53, the interference received by the wireless station 0 based on the transmission signal 8cos (ω _k t) (k = 1 to n) transmitted from the wireless stations 1 to 3. The interference cancellation signal contained in the received signal r (t) is eliminated by dynamically generating an interference cancellation signal with the same amplitude as that of the signal and synthesizing this interference cancellation signal and the received signal r (t). To do.

  The invention made by the present inventor has been specifically described based on the embodiment of the invention, but the invention is not limited to the embodiment of the invention and does not depart from the gist of the invention. Of course, various changes can be made.

It is a figure which shows a radio station provided with the interference removal apparatus of embodiment of this invention. It is a figure for demonstrating schematic structure of the interference removal apparatus of embodiment of this invention.

Explanation of symbols

0 to 4 ... Wireless station 5 ... Interference canceller 6, 15, 25, 35 ... Transmit / receive antenna 7, 12, 22, 32 ... Transmitter 8, 13, 23, 33 ... Receiver 11, 21, 31 ... Input means 9 ... Switches 14, 24, 34 for supplying the transmission signal of the transmission apparatus (Tx) to the transmission / reception antenna and outputting the reception signal to the interference cancellation apparatus, and supplying the transmission signal of the transmission apparatus (Tx) to the transmission / reception antenna and the reception signal Is input to the receiving device (Rx) 50 ... interference canceller input 51-53 ... interference cancel block 54 ... synthesizer 511, 521, 531 ... hybrid 512, 513, 518, 519 ... multiplier 522, 523,528 529, 532, 533, 538, 539 ... multipliers 514, 515, 524, 525, 534, 535 ... LPF
516, 517, 526, 527, 536, 537 ... inverse circuit

Claims (4)

An interference cancellation apparatus that removes the interference signal from a received signal of a desired wave in which the interference signal is mixed,
Interference source signal input means not subject to fluctuations due to radio wave environment,
Orthogonal demodulation means for orthogonally demodulating the received signal with the interference source signal;
Low-pass filter means for low-pass filtering the output signal of the quadrature demodulating means to extract only the fluctuation elements of the interference signal;
Orthogonal modulation means for orthogonally modulating the interference source signal based on the output of the low-pass filter means;
With
An interference cancellation apparatus that removes the interference signal from the received signal based on an output of the orthogonal modulation means. The interference cancellation apparatus according to claim 1,
An inverter that is disposed between the low-pass filter means and the quadrature modulation means, and converts the output of the low-pass filter means into a reverse phase;
Adding means for adding the output of the orthogonal modulation means and the received signal;
An interference cancellation apparatus comprising: An interference removal apparatus that removes the plurality of interference signals from a received signal of a desired wave in which a plurality of interference waves are mixed,
Input means for a plurality of interference source signals not affected by the radio wave environment;
A plurality of orthogonal demodulation means for orthogonally demodulating the received signal by each interference source signal for each of the plurality of interference source signals;
A plurality of low-pass filter means for low-pass filtering the output signals of the plurality of quadrature demodulation means to extract only the variable elements for each of the plurality of interference signals;
A plurality of orthogonal modulation means for orthogonally modulating the plurality of interference source signals based on outputs of the plurality of low-pass filter means;
With
An interference removing apparatus that removes the plurality of interference signals from the received signal based on outputs of the plurality of orthogonal modulation means. The interference cancellation apparatus according to claim 3.
A plurality of inverters arranged between the plurality of low-pass filter means and the plurality of quadrature modulation means, respectively, for converting the outputs of the plurality of low-pass filter means into opposite phases;
Adding means for adding the outputs of the plurality of orthogonal modulation means and the received signal;
An interference cancellation apparatus comprising:

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