JPS6266729A - Same frequency repeating system - Google Patents

Abstract

PURPOSE:To eliminate an interference between transmission and reception signals by interchanging mutually frequencies used in individual routes at every repeating station when a common-frequency radio communication line of plural routes is repeated. CONSTITUTION:A reception signal 101 corresponding to a route having a carrier frequency f1 passes a reception antenna 1, a receiver 2, an adding circuit 4, and a demodulator 5 and is demodulated and is modulated to a transmission signal 103 having a carrier frequency f2 by a modulator 6 and a transmitter 8 and is transmitted from a transmission antenna 9. Similarly, a reception signal 102 corresponding to a route having the carrier frequency f2 becomes a transmission signal 104 having the carrier frequency f1 by repeating and is transmitted. Then, the interference between transmission and reception is not caused because transmission and reception frequencies are different from each other on the same route, and variable frequency characteristic filters including correlation detectors 19 and 22 are used to eliminate the interference between routes. Thus, the interference between transmission and reception signals is eliminated to hold the line quality well.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a same frequency relay system, and in particular, in a wireless communication line that uses the same carrier frequency for transmission and reception, it is possible to reduce line quality due to interference of a transmitted signal with a received signal at a relay station. This invention relates to a same frequency repeating system that improves deterioration.

[Conventional example]

Conventionally, a so-called two-frequency system has been used in microwave band wireless communication lines formed via relay stations, and the frequencies of transmission and reception at the same station are set to prevent interference between transmission and reception. Different frequencies are used for this purpose.

Therefore, at each relay station in a wireless communication line, frequency allocation is performed in such a way that the transmission and reception frequencies are alternated for each relay section. However, recently,
The application of lines has been proposed from the viewpoint of effective use of the frequencies allocated to wireless communication lines in the microwave band.

What is shown in FIG. 2 is a block diagram showing the main parts of a relay system corresponding to one direction of one route of a relay station in the same frequency wireless communication line, including a receiving antenna 25, a receiver 26, and a receiving antenna 25, a receiver 26, A local oscillator 27 that generates a local oscillation signal for converting the carrier frequency of a signal to a predetermined intermediate frequency, a demodulator 28, a modulator 29, a carrier generation circuit 30, a transmitter 31, and a carrier wave for a transmission signal. It includes a local oscillator 32 that generates a local oscillation signal for frequency conversion to generate a frequency, and a transmitting antenna 32.

In FIG. 2, a received signal 105 with a carrier frequency fl
is input to the receiver 26 via the receiving antenna 25. The receiver 26 is equipped with a frequency converter, an intermediate frequency amplifier, etc., and according to the local oscillation signal sent from the local oscillator 27, the received signal 105 is converted into a predetermined intermediate frequency signal, and the received signal 105 is converted into a predetermined intermediate frequency signal. The signal is amplified by a frequency amplifier and input to the demodulator 28. The demodulator 28 is configured to use a quadrature phase periodic detection method as a demodulation method in response to the input of, for example, a digital multiphase phase modulated wave or a digital multilevel quadrature amplitude modulated wave. It is equipped with an equalization circuit and the like for removing amplitude distortion and phase distortion contained in the signal.

The demodulated signal demodulated and output by the demodulator 28 is input to the modulator 29, where the demodulated signal modulates the carrier signal sent from the carrier wave generation circuit 30. The modulated wave signal output from the modulator 29 is input to the transmitter 31, and depending on the local oscillation signal sent from the local oscillator 32, the carrier wave frequency f of the received signal 105 is
The signal is converted into a transmission signal with a carrier frequency equal to 1, power amplified, and transmitted as a transmission signal 106 from the transmission antenna 33 to the opposite station. In this same frequency relay method, since the transmitting and receiving frequencies are the same, interference signals are generated at the relay station itself due to leakage of the transmitted signal to the received signal.As a countermeasure against this interference signal, the demodulator It is considered that the equalization circuit provided in 28 removes the interference signal.

[Problem that the invention seeks to solve]

In the above-mentioned same frequency relay method, since the baseband signals for the received signal and the transmitted signal are the same, there is a difference between the baseband signal of the original received signal and the baseband signal of the interference signal due to leakage of the transmitted signal. Since the cross-correlation is large, and therefore it is extremely difficult to distinguish between the original received signal and the interference signal, there is a drawback that the interference signal caused by the leakage of the transmitted signal to the received signal cannot be sufficiently removed. be.

[Means for solving problems]

In order to solve the above-mentioned problems, the same frequency relaying method of the present invention has a relay station of the same frequency wireless communication line of multiple routes, and the receiving frequency and the transmitting frequency are adjusted for each relay system corresponding to each route in the multiple routes. A means for setting the frequency to a different frequency is provided.

〔Example〕

Hereinafter, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing the main parts of a pair of relay systems in one embodiment of the present invention. As shown in FIG. 1, this relay system includes receiving antennas 1 and 10.
, receivers 2 and 11, local oscillators 3 and 12, adder circuits 4 and 14, demodulators 5 and 15, modulators 6 and 13, carrier wave generation circuits 7 and 16,
transmitters 8 and 17; transmitting antennas 9 and 18;
Correlation detector 19 and transversal filter 20
a variable frequency characteristic filter 21 including a correlation detector 22
and a variable frequency characteristic filter 24 including a transversal filter 23.

In FIG. 1, received signals 101 and 102 corresponding to two routes with carrier frequencies fl and fl are transmitted to receivers 2 and 1 via receiving antennas 1 and 10, respectively.
1 is input. The receivers 2 and 11 are each equipped with a frequency converter, an intermediate frequency amplifier, etc.
Received signals 101 and 102 are converted into predetermined intermediate frequency signals by local oscillation signals sent from local oscillators 3 and 12, respectively, amplified by the intermediate frequency amplifier, and input to corresponding adder circuits 4 and 13, respectively. be done. In adder circuits 4 and 13, interference cancellation signals 111 and 112 sent from transversal filters 20 and 23 included in variable frequency characteristic filters 21 and 24, respectively, are added, and the transmitted signal leaking into the received signal is added. The interference signals caused by the interference signals are reduced and input to demodulators 5 and 14, respectively. The demodulators 5 and 14 respond to an input of, for example, a digital multiphase phase modulated wave or a digital multilevel quadrature amplitude modulated wave, and
The demodulation method is a quadrature phase coherent detection method, and the demodulated signals 105 and 106 output from the respective demodulators 5 and 14 are sent to the modulator 6, the correlation detector 22, and the modulator 15, respectively. and correlation detector 19
sent to. In modulators 6 and 15, predetermined carrier signals inputted from carrier wave generation circuits 7 and 16, respectively, are modulated using the corresponding demodulated signals as baseband signals, and respective modulated wave signals 11 are modulated.
3 and 114 are sent to corresponding transmitters 8 and 17, and transversal filter 2, respectively.
3 and 2o. Transmitters 8 and 17 include
Each of them is equipped with a frequency converter, a power amplifier, etc., and the carrier frequency of the modulated wave signal is changed to the carrier frequency of the modulated wave signal through the local oscillation frequency inputted to the local oscillators 3 and 12, respectively. converted, amplified to a predetermined power level, and transmitted to the transmitting antenna 9.
and 18, the transmitted signals 103 and 104, respectively.
The signal is sent to the opposite station as a signal.

Therefore, in the route corresponding to the received signal with carrier frequency fl, the transmitted signal 103 with carrier frequency f: corresponds, and in the route corresponding to the received signal 102 with carrier frequency f, the carrier frequency is In the pair of relay systems shown in FIG. 1, the receiving frequency and the transmitting frequency are respectively set to different frequencies.

In the pair of relay systems in this embodiment described above, the modulated wave signal 113 in the intermediate frequency band that can be output from the modulator 6 on the route corresponding to the received signal 101 (hereinafter referred to as route A) is passed through the variable frequency characteristic filter 24. The signal is sent to a transpurple filter 23 included in the filter.

Further, the intermediate frequency band modulated wave signal 114 output from the modulator 15 on a route corresponding to the reception route 102 (hereinafter referred to as route B) is sent to the transversal filter 20 included in the variable frequency characteristic filter 21. It will be done. On the other hand, the error signal 107 output from the demodulator 5 on the A route and the error signal 108 output from the demodulator 14 on the B route are transmitted to the correlation detector 1, respectively.
9 and 22. The demodulated signal 105 of the A route is superimposed with the interference signal caused by the leakage of the baseband signal of the A route and the transmission signal of the B route, and the demodulated signal 106 of the B route is superimposed with the baseband signal of the A route and the interference signal caused by the leakage of the transmitted signal of the B route. The signal and the interference signal caused by the leakage of the transmission signal of route A are superimposed. Furthermore, the error signals 107 and 108 output from the demodulators 5 and 14 include an interference signal due to the leakage of the transmission signal of the B route and an interference signal due to the leakage of the transmission signal K of the A route, respectively. . Therefore, the correlation detector 19 takes the cross-correlation between the demodulated signal 106 and the error signal 107, and detects the interference signal from the B route leaking into the received signal from the A route using the demodulated signal 106 as a reference. , a plurality of control @signals 1 are used to minimize this interference signal.
09 is output, and the weighting of each corresponding tap of the transversal filter 2o is input to the circuit. The modulated wave signal 114 in the intermediate frequency band of the B route output from the modulator 15 is input to the transversal filter 20, and the weighting of each tap by the plurality of control signals 109 is controlled by the circuit. Through this action, an intermediate frequency band interference cancellation signal 111 is output. This interference canceling signal 111 is input to the adding circuit 4, where it is added to the intermediate frequency band reception signal of kA--) sent from the receiver 2, and the superimposed interference signal is eliminated. Similarly, through the action of the variable frequency characteristic filter 24 including the correlation detector 22 and the transversal filter 23, the intermediate frequency band of the B route is received by the interference cancellation signal 112 input to the adder circuit 13. Interfering signals superimposed on the signal are removed. In this case, the frequencies fl and f2 are separated to such an extent that mutual interference between the pair of relay systems does not occur, and there is no interference between transmitted and received signals on the same route, which poses no problem.

〔Effect of the invention〕

As described above, the present invention is applied to multiple routes of the same frequency wireless communication line, eliminates interference caused by leakage of transmitted signals to received signals at relay stations, and improves line quality of the same frequency wireless communication line. It has the effect of being able to maintain normal conditions.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the main parts of a relay station in an embodiment of the present invention, and FIG. 2 is a block diagram showing the main parts of a relay station in a conventional same frequency relay system. In the figure, 1, 10.25...Receiving antenna, 2.22.26...Receiver, 3, 12, 27
．． 32...Local oscillator, 4.13...Addition circuit, 5,14.28...Demodulator, 6,15.
29...Modulator, 7,16°30...
Carrier wave generation circuit, 8, 17.31...Transmitter, 9
, 18.33...Transmission antenna, 19,17°31...Transmitter, 9,18,33...
Transmission antenna, 19, 22...correlation detector,
20.23...Transpersal filter,
21.24...Variable frequency characteristic filter. Agent: Susumu Uchihara, patent attorney.

Claims (2)

[Claims] (1) In a relay station of the same frequency wireless communication line for multiple routes, the relay station is characterized by comprising means for setting the receiving frequency and the transmitting frequency to different frequencies for each relay system corresponding to each route in the multiple routes. Same frequency relay method. (2) In the relay station, as part of the means for setting the receiving frequency and the transmitting frequency to different frequencies for each route, between a pair of relay systems in which the receiving frequency and the transmitting frequency are set to the same frequency, Claims characterized by comprising signal waveform modification means having variable frequency characteristics for introducing the modulated wave signal on the modulator output side of each relay system into the demodulator input side of the corresponding relay system. Same frequency repeating method described in paragraph (1).