JPH03139031A - Interference compensation system - Google Patents

Abstract

PURPOSE:To eliminate the need for an exclusive separate antenna and to decrease an interference level by inverting a phase of one signal series in two received signal series received by the space diversity system, synthesizing it with the other signal series to emphasize the interference signal component, thereby compensating the interference through the use of the emphasized component. CONSTITUTION:Two received reception signal series are inputted from a space diversity synthesis section 10 to an inverse phase synthesis section 11, the phase from a main antenna 9M in the two received signal series is inverted and the result is synthesized with the signal from a subantenna 9S to emphasize the interference signal component. Then an interference demodulation section 13 demodulates a local signal synchronously with the main signal and an interference identification section 14 identifies the clock signal synchronously with the main signal and only the interference signal is extracted by an interference extraction section 15. Thus, a compensation signal generating section 16 is used to generate a compensation signal cancelling the interference component included in the main signal and the interference component is removed from the main signal.

Description

[Detailed description of the invention] Industrial field of application Conventional technology (Fig. 5) Means for solving the problems to be solved by the invention (Fig. 1) Effect (Fig. 1) Examples (Fig. 5) (Figures 2 to 4) Effects of the invention [Summary] Regarding the interference compensation method for compensating for interference from other propagation paths in digital radio systems, the present invention is capable of stably detecting interference wave components at any time without using a dedicated separate antenna. With the aim of achieving high interference compensation by making it possible to detect interference, we invert the phase of one of the two signal sequences received by the space diversity method and use this as the signal sequence for the other signal. After emphasizing the interference signal component by combining it with the main signal sequence, the interference signal is detected by canceling the main signal with the emphasized signal and the signal from the main signal sequence,
Further, a compensation signal is created from the interference signal, and interference compensation is performed based on the compensation signal.

[Industrial Application Field] The present invention relates to an interference compensation method for compensating for interference from other propagation paths in digital radio systems.In recent years, digital radio systems have been improving frequency efficiency and increasing line capacity. To measure this, multilevel modulation technology has been adopted, and at present, the 256 QAM system is already in practical use.

Although transmission capacity increases as multi-value technology progresses, the amount of deterioration in the equivalent carrier-to-noise ratio (C/N) due to various causes of deterioration (waveform distortion and jitter) also increases, making it difficult for the equipment itself to Increasingly, strict characteristics are required.

Furthermore, as multi-leveling progresses, it becomes more susceptible to interference from other propagation paths, and an interference compensation system is required to cope with this.

In such interference compensation, an interference signal is detected, and the detected interference signal is subtracted from a received signal containing a mixture of the interference signal and the main signal.

[Prior Art] FIG. 5 is a block diagram showing an example of a conventional vector correlation type interference compensator. In FIG. 5, 100 is an interference compensator, and this interference compensator 1° Variable phase shifter 1o1. that adjusts the phase of the FM signal as a signal. Same FM
A variable attenuator 102 that adjusts the amplitude of the signal. Variable phase shifter 1
01 and a control circuit 103 that controls the variable attenuator 102
．． A hybrid section 104 that combines a signal in which a main signal and an interference signal are mixed and an interference signal whose phase and amplitude have been adjusted, and an amplifier 105 that amplifies the signal from the hybrid section 104.
have.

Further, 106 is a demodulation section, and 107 is an A/D conversion section (identification section).

In the interference compensator having such a configuration, the FM signal as an interference signal is transmitted through the variable phase shifter 101 and the variable attenuator 10.
After the phase and amplitude are adjusted in step 2, the hybrid section 10
At step 4, the interference signal is removed by being combined with a signal including the main signal and the interference signal.

[Problem to be solved by the invention] However, although such conventional devices are effective against interference such as FM signals [which can almost be approximated by CW (unmodulated wave)], they are not effective against interference. Since it is a method of receiving with an antenna, the characteristics are greatly affected by the reception situation, and there is also the problem that a separate antenna is required.

The present invention was made in view of such problems, and it is possible to perform high interference compensation by making it possible to stably detect interference wave components at any time without using a separate dedicated antenna. The purpose is to provide an interference compensation method.

[Means to solve the problem] FIG. 1 is a block diagram of the principle of the present invention.

In FIG. 1, reference numeral 1 denotes an anti-phase combining unit, which inverts the phase of the signal sequence from one of the antennas for two received signal sequences received by the space diversity method. , which is combined with the signal sequence from the other antenna, thereby making it possible to emphasize the interference signal component by changing the ratio of the main signal to the interference signal.

2 is an interference detection unit, and this interference detection unit 2 eliminates the interference signal by canceling the main signal using the signal whose interference signal component has been emphasized by the anti-phase combining unit 1 and the signal from the main signal sequence. It is something to detect.

3 is a compensation signal creation section, and this compensation signal creation section 3 performs appropriate processing on the interference signal from the interference detection section 2 to create a compensation signal for canceling the interference component contained in the main signal. It is something.

4 is a hybrid section, and this hybrid section 4 synthesizes a signal containing an interference component in the main signal and a compensation signal from the compensation signal generation section 3, and cancels the interference signal with the compensation signal, thereby generating a main signal. This is to remove interference components from.

[Operation] In the interference compensation method of the present invention described above, for two received signal sequences received by the space diversity method, the anti-phase combining section 1 inverts the phase of one of the signal sequences and inverts the phase of the other signal sequence. By combining with the other signal sequence,
After the interference signal component is emphasized, the interference detection unit 2 detects the interference signal by canceling the main signal using the signal with the interference signal component emphasized and the signal from the main signal sequence.

Then, the compensation signal creation unit 3 creates a compensation signal from the detected interference signal, and the hybrid unit 4 combines the signal containing the interference component in the main signal and the compensation signal from the compensation signal creation unit 3. The interference component is removed from the main signal by canceling the interference signal with the compensation signal.

[Example] The present invention will be described in detail below with reference to one drawing.

FIG. 2 is a block diagram showing an embodiment of the present invention. In FIG. 2, 9M is a main antenna, 9S is a sub-antenna, and 10 is a space diversity combining section (SD section).

Here, the space diversity combining section 10 operates to cancel interference waves or multipath signals.
An infinite phase shifter 10A that performs vR adjustment to rotate the phase of the signal from the sub-antenna 9S, and this infinite phase shifter 1
It includes a hybrid section 10B that combines the signal from 0A and the signal from main antenna 9M. That is,
In this space diversity combining unit 10, if the vector relationship between the signal from the main antenna 9M and the signal from the sub antenna 9S is as shown in FIG. The phase of the interference component of the signal from the antenna 10S is rotated so that it has an opposite phase relationship with the interference component of the signal from the main antenna 9M, as shown in FIG. 3(b). When the related components are combined in the hybrid section 10B, the result is as shown in FIG. 3(c). This figure 3(c)
From this, it can be seen that this space diversity combining section 1o operates to cancel the interference waves.

Then, the output from the hybrid section 10B in this space diversity synthesis section 10 is output from the bandpass filter 1.
7 and an amplifier 18 for automatic gain control (AGC). Also,
Signal from main antenna 9M and infinite phase shifter 10A
The signal from the sub-antenna 9S that has passed through is input to the anti-phase combining section 11.

The anti-phase combining unit 11 has a function of anti-phase and combining one of the two received signal sequences received by the space diversity method, and in FIG. 2, for example, the signal sequence from the main antenna 9M. This is to invert the phase of the signal sequence from the sub-antenna 9S and combine it with the signal sequence from the sub-antenna 9S. It is provided with a hybrid section 11B that synthesizes with the signal sequence of the hybrid section 11B, and further controls the gain of the output of the bandpass filter 11C and the bandpass filter 11C that passes only the required frequency components of the signal synthesized by the hybrid section 11B. It is equipped with an amplifier 11D for automatic gain control.

That is, in this anti-phase combining unit 11, the space diversity combining unit 10 rotates the interference component of the signal from the sub-antenna 9S so that it has an anti-phase relationship with the interference component of the signal from the main antenna 9M. When the phase inverter 11A further inverts the phase of the signal sequence from the main antenna 9M, the relationship [see FIG. 4(a)] becomes as shown in FIG. 4(b). When the resulting components are combined in the hybrid section 11B, the result is as shown in FIG. 4(c). From FIG. 4(c), it can be seen that the anti-phase synthesis unit 11 can emphasize the interference signal component by changing the ratio between the main signal (see the black triangle arrow) and the interference signal (see the white triangle arrow). Recognize.

The signal from the anti-phase synthesis section 11 is input to the interference detection section (interference signal detection section) 12 via the automatic gain control amplifier 11D.

Here, the interference detection unit 12 includes an interference demodulation unit 13°, an interference identification unit 14, and an interference extraction unit 15.

First, the interference demodulator 13 demodulates the signal in which the interference signal from the antiphase synthesizer 11 is emphasized.

Note that the local signal Lo input to the demodulator 13 is the local signal Lo(
This local signal LO is controlled by the required control signal V
(produced using CO24).

The interference identification unit 14 identifies the code of the signal demodulated by the demodulator 13, and has an A/D converter as its main component. Note that the clock CLK input to the identification unit 14 is the clock CL for the main signal sequence identification unit 20.
This is a clock synchronized with K.

By the way, regarding the A/D converter of this identification section 14,
Usually, there is something called bit precision, and if the input signal is small, the A/D conversion precision decreases due to quantization noise. However, in this embodiment, since the interference signal, which is originally low in level, is emphasized, the A/D conversion accuracy of the interference signal component is not reduced. That is, in this case, since the purpose is to detect the interference component in the interference extraction section 15 at the next stage, it is of great significance that the A/D conversion accuracy of the interference component is improved.

The interference extraction unit 15 extracts a signal with enhanced interference signal components, and
The signal from the main signal sequence (output of the identification unit 20) is used to eliminate the main signal and extract the interference signal.
A transversal filter section 15A, a delay section 15B, and a hybrid section 15C.

Control unit 15 for transversal filter unit 15A
It has 0.

Here, the transversal filter section 15A receives a signal from the identification section 20 as a signal from the main signal sequence,
By controlling the weighting at that tap,
It adjusts the output.

The delay section 15B receives the signal from the identification section 14 and delays the signal from the identification section 14 by a delay amount due to signal processing in the transversal filter section 15A, and for example, a shift register is used.

The hybrid section 15G combines the signal from the transversal filter section 15A and the signal from the delay section 15B to eliminate the main signal.

This allows interference signals to be detected.

The control section 15D receives the signal to the transversal filter section 15A and the interference signal extracted from the hybrid section 15C, and controls the weighting at each tap of the transversal filter section 15A. A transversal filter section 15 integrates the correlator that receives the signal to 15A and the interference signal extracted from the hybrid section 15C, and the output of this correlator.
It consists of an integrator etc. that outputs A8 control signals.

Here, the transversal filter section 15A that adjusts the output so as to cancel the main signal may theoretically receive the signal from the identification section 14 instead of the signal from the main signal sequence (in this case, Although it is possible (the main signal sequence signal is input to the delay unit 15B), it is better to input the signal from the main signal sequence to the transversal filter unit 15A as in this embodiment. That is, if the signal from the identification unit 14 is input to the transversal filter unit 15A, even though the interference signal component of this signal is emphasized, the transversal filter unit 15
This is because the adjustment operation by A may reduce the interference component.

Furthermore, 16 is a compensation signal creation section, and this compensation signal creation section 16 performs appropriate processing on the interference signal obtained by canceling the main signal in the interference extraction section 15.

It creates a compensation signal to cancel the interference component contained in the main signal, and as this compensation signal creation section 16, an interference compensator using a conventionally known transversal filter section 16A and a control section 16B is used. Ru. Here, the operation of the control section 16B is almost the same as that of the control section 15D of the interference extraction section 15 described above.

In addition, as a signal containing an interference component in the main signal, the output from the space diversity combining section 10 is input to a demodulator 19 via a bandpass filter 17 and an amplifier 18, where it is demodulated, and then the A/D Identification section 20 consisting of a conversion section
After the code is identified in the transversal equalizer 21, the signal delayed to match the interference signal detection time is used in the delay unit 22, and the signal containing the interference component in this main signal and the extracted interference signal are used. The compensation signal based on 1 is combined in the hybrid section 23, and the interference component is removed from the main signal by canceling the interference signal with the compensation signal.

Note that each signal of the main antenna system and sub antenna system is composed of I and Q channel signals, respectively.

With the above-described configuration, first, two received signal sequences received by the space diversity method are input from the space diversity combining section 1o to the anti-phase combining section 11. This anti-phase combining unit 11 inverts the phase of the signal sequence from the main antenna 9M with respect to the two received signal sequences received by the space diversity method, and combines this with the other signal sequence from the sub-antenna 9S. By combining, interference signal components are emphasized. Thereafter, the interference demodulator 13 demodulates the local signal synchronized with the main signal, and the interference identifier 14 identifies the signal with a clock synchronized with the main signal, and then the interference extractor 15
, the main signal component is removed and only the interference wave component is extracted from the signal with the interference signal component emphasized and the signal from the main signal sequence.

In this way, an interference signal is extracted by erasing the main signal, but this extracted interference signal is subjected to appropriate processing in the compensation signal creation section 16 to remove the interference components contained in the main signal. It is supplied to the hybrid section 23 as a compensation signal for canceling out, and further in this hybrid section 23,
The compensation signal from the compensation signal generation section 16 and the signal containing the interference component in the main signal (this signal is the output from the space diversity synthesis section 10 are input to the demodulator 19 via the bandpass filter 17 and the amplifier 18). , demodulated here, and further code identified by an identification unit 20 consisting of an A/D conversion unit, and then passed through a transversal equalizer 21 to a delay unit 22.
(delayed to match the interference signal detection time) are combined. Thereby, the interference signal is canceled by the compensation signal, and the interference component is removed from the main signal.

In this way, the 2
For two received signal sequences, the interference signal component is emphasized by inverting the phase of one signal sequence and combining it with the other signal sequence, and then converting this interference signal component into the emphasized signal. , the interference signal is detected by erasing the main signal with the signal from the main signal sequence, and a compensation signal is created from this interference signal, and interference compensation is performed based on the above compensation signal. Thus, there is no need to use a separate dedicated antenna, and even when the interference level is small, interference wave components can be extracted stably, thereby making it possible to effectively compensate for interference.

In the above-mentioned embodiments, the digital interference compensator was explained as an example, but the present invention can be similarly applied to an analog interference compensator.

[Effects of the Invention] As detailed above, according to the interference compensation method of the present invention,
By inverting the phase of one of the two received signal sequences received by the space die patch method and combining it with the other signal sequence,
After emphasizing the interference signal component, the interference signal is detected by canceling the main signal using the signal with the emphasized interference signal component and the signal from the main signal sequence, and then a compensation signal is generated from this interference signal. Since interference compensation is performed based on the above compensation signal, there is no need to use a separate dedicated antenna as in the past, and furthermore, even when the interference level is small, interference wave components can be extracted stably. This has the advantage that interference compensation can be performed effectively.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the principle of the present invention, Fig. 2 is a block diagram showing an embodiment of the present invention, Fig. 3 is a vector diagram for explaining the operation in the space diversity synthesis section, and Fig. 4 is the reverse FIG. 5 is a vector diagram for explaining the operation of the phase synthesis section. FIG. 5 is a block diagram showing a conventional example. In the figure, 1 is an anti-phase synthesis unit, 2 is an interference detection unit 8, 3 is a compensation signal generation unit, 4 is a hybrid unit, 9M is a main antenna, 9S is a sub-antenna, 10 is a space diversity synthesis unit, and 10A is an infinite shift unit. A phaser, 10B is a hybrid part. 11 is an anti-phase synthesis section, 11A is a phase inversion section, 11B is a hybrid section, and 11G is a bandpass filter. 11D is an amplifier, 12 is an interference detection section, 13 is an interference demodulation section, 14 is an interference identification section, 15 is an interference extraction section, and 15A is a transversal filter section. 15B is a delay section, 150 is a control section, and 16 is a compensation signal generation section. 16A is a transversal filter section, 16B is a control section, 17 is a band pass filter, 18 is an amplifier, 19 is a demodulation section, 20 is an identification section, and 21 is a transversal equalizer. 22 is a delay section, 23 is a hybrid section, and 24 is a vCO.

Claims (1)

[Claims] Regarding two received signal sequences received by the space diversity method, by inverting the phase of one of the signal sequences and combining it with the other signal sequence,
After emphasizing the interference signal component, the interference signal is detected by canceling the main signal with the signal with the emphasis of the interference signal component and the signal from the main signal sequence, and then a compensation signal is generated from the interference signal. 1. An interference compensation method characterized by creating a compensation signal and performing interference compensation based on the compensation signal.