JPH0746201A - Propagation path simulator - Google Patents

Abstract

(57) [Abstract] [Purpose] A device for simulating a radio channel of mobile communication, which can simulate a multipath channel when the level of each elementary wave, the spread of delay time, and the phase shift change with time. The purpose is to provide a simulation device. A distribution circuit that distributes an input signal to a plurality of systems, and delay times of a plurality of output signals of the distribution circuit,
A plurality of conversion circuits that change the level and the phase, a combination circuit that combines the output signals of all the conversion circuits, and a control circuit that controls the amount of change in the delay time, level, and phase of each of the conversion circuits. Then, the control circuit is configured to change the delay time, the level, and the phase change amount of each of the conversion circuits according to the passage of time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a propagation path simulator for simulating an actual propagation path when a minimum zone is applied in mobile communication.

[0002]

2. Description of the Related Art FIG. 5 shows an example of the configuration of a conventional propagation path simulator. This propagation path simulation device includes a distributor 503, a combiner 509, a 90-degree phase shifter 504, mixers 507 and 508,
Gaussian noise generation circuits 505 and 506, amplifiers 510 and 5
12 and a delay time generation circuit 511. Input terminal 50
The high frequency signal input from 1 is input to the Rayleigh fading generation unit 502, and is distributed by the distributor 503 into two systems of high frequency signals. The distributed high frequency signal of one system is phase-shifted by the 90-degree phase shifter 504.

The high frequency signals of the two systems are respectively multiplied by the mixers 507 and 508 with the signals generated by the Gaussian noise generation circuits 505 and 506 independent from each other, and are synthesized by the synthesizer 509. The series of signal processing up to this point is quadrature modulation using Gaussian noise. The high frequency signal quadrature-modulated by Gaussian noise becomes a signal subjected to Rayleigh fading. The high frequency signal subjected to Rayleigh fading is input to the delay time generation circuit 511 after being amplified by the level adjusting amplifier 510.

The high-frequency signal is delayed by a delay time generation circuit 511 for a prescribed time, and becomes a signal that has undergone fluctuations in level, phase, and delay time as in the case of propagating in a multiple wave propagation path generated in land mobile communication. . Finally, the high frequency signal is amplified by the level adjusting amplifier 512 and is output to the output terminal 51.
It is output from 3.

In the above-described quadrature modulation using mutually independent Gaussian noise, the number of radio waves, that is, elementary waves arriving at the receiving antenna from each direction is sufficiently large, and the levels of the elementary waves are almost the same. Is assumed.

By using this conventional propagation path simulator, various transmission characteristics under Rayleigh fading in which the level of each elementary wave in the multipath propagation path, the spread of the delay time, and the phase shift do not change with time are obtained. It can be measured in laboratory experiments.

[0007]

At present, in land mobile communications, in order to increase the subscriber capacity, a method of applying a minimum zone having a low base station antenna height is being studied. In this minimum zone, as the positional relationship between the base station and the mobile station changes with time, the spread of the level of the elementary waves also changes with time. On the other hand, in a wireless zone where the base station antenna height is high as in the conventional case, there is often no line of sight between the base station mobile stations, and the spread of the level of the elementary waves hardly changes.

Considering the case where the mobile station moves from the vicinity of the base station to a distance in the minimum zone, if the mobile station is in the vicinity of the base station and the base station can see the mobile station, The base station has an element wave that directly arrives and an element wave that arrives after being reflected, diffracted, and scattered, so that the propagation path length spreads widely, and the reflected wave with a long propagation path length causes level loss due to reflection. The level spreads greatly because it is also received.

On the other hand, when the mobile station moves away from the base station and the mobile station cannot see through the base station, the waves propagating between the base stations and the mobile stations have a small propagation path length and all the waves. The level spread is small because the wave suffers level loss due to reflection, diffraction, and scattering.

The temporal change in the positional relationship between the base station and the mobile station in the minimum zone is due to the spread of the level of each wave,
The delay time spread of each elementary wave and the phase shift due to reflection, diffraction, and scattering are also changed. The former is clear from the change in the spread of the propagation path described above, and the latter is the situation such as the incident angle, diffraction angle, and scattering surface of each elementary wave in the propagation path that changes due to the change in the positional relationship between the base station and the mobile station. This is because.

As described above, with the passage of time in the minimum zone, generally, the level of each elementary wave and the spread of the delay time and the state of the multiple wave propagation path such as the phase shift due to reflection, diffraction, and scattering change.

However, in the conventional propagation path simulating device, since the quadrature modulation by Gaussian noise is performed on the assumption that the levels of the elementary waves are all the same, it is not possible to change the level spread of each elementary wave with time. It was possible. Further, the conventional device has only the delay time generation circuit that delays the composite wave of each elementary wave, and it is impossible to change the spread of the delay time of each elementary wave with time. In addition to these, the conventional device does not have a circuit in which the operator can directly set the phase shift due to reflection, diffraction, and scattering of each elementary wave. For these three reasons, the conventional device has a problem that it is not possible to simulate a multipath propagation path when the level of each elementary wave, the spread of delay time, and the phase shift change with time.

An object of the present invention is to provide a propagation path simulating device capable of simulating a multiple wave propagation path when the level of each elementary wave, the spread of delay time, and the phase shift change with time.

[0014]

According to the present invention, the above-mentioned problems are solved by the means described in the claims.

That is, the present invention comprises a distribution circuit for distributing an input signal to a plurality of systems, and a plurality of conversion circuits for changing the delay time, level and phase of each of a plurality of output signals of the distribution circuit. A combination circuit that combines the output signals of all the conversion circuits, and a control circuit that controls the amount of change in delay time, level, and phase of each of the conversion circuits,
The control circuit is a propagation path simulating device configured to change the amount of change in delay time, level and phase of each of the conversion circuits according to the passage of time.

[0016]

As described above, the present invention provides means for distributing an input signal by the number of propagation paths of elementary waves, and delay time, phase, and
And means for controlling the level and means for recombining the distributed signals.

Then, the input signal is distributed by the distribution circuit as many as the propagation paths of the elementary waves forming the multiple wave propagation path, and the delay time, phase, and level of each signal distributed by the control circuit are changed. By controlling the circuit that operates according to the time change of the propagation path and recombining the signals distributed by the combining circuit, the level of each elementary wave and the spread of the delay time and the multipath propagation when the phase shift changes with time We have realized a propagation path simulator that can simulate the path.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the propagation path simulator of the present invention. The propagation path simulator of the present invention includes a distributor 103, a plurality of variable delay time generation circuits 105, 106,
107, a plurality of variable phase shift circuits 108, 109, 110,
Multiple variable attenuation circuits 111, 112, 113, combiner 1
19, the delay time in the variable delay time generation circuits 105, 106, 107, the phase shift amount in the variable phase shift circuits 108, 109, 110 and the variable attenuation circuits 111, 112, 113
And a control unit 114 for time-controlling the amount of attenuation. The control unit 114 includes a parameter input device 115, a calculation processor 116, a memory 117, and a control signal output device 118.

FIG. 2 is a flow chart showing the control operation of the control unit 114 of this embodiment. (S-1) ~ in the figure
The symbol (S-8) represents a processing step and corresponds to the following description. A high frequency signal is input from the signal generator 100 of FIG. 1 to the RF signal input terminal 101, and before the measurement is started, the condition of the propagation path to be simulated is first input from the parameter input device 115 (S-1).

Based on the parameters, the calculation processor 116
Thus, the delay time, the phase shift amount, and the attenuation amount of each elementary wave that changes with time are calculated (S-2). A control data table is created on the memory 117 from this calculation result (S-3). When the control data table has been created, a control start signal input waiting state is entered (S-4).

At the start of measurement, the signal generator 100 simultaneously outputs a high frequency signal and a control start signal. At the same time when the control start signal is input to the control unit input terminal 102, the memory 117
The reading of the control data table of the delay time, the amount of phase shift, and the amount of attenuation created above starts (S-5).

These control data are sent to the control signal output device 11
8 is output to the wave propagation simulation unit 104 according to time (S-6). Finally, when the measurement ends and the control stop signal is input from the signal generator 100 to the control unit input terminal 102 (S-7), the output of the control signal is stopped (S-8).

FIG. 3 is a flowchart showing the signal processing of this embodiment. Reference numerals (S-1) to (S-5) are the same as in the case of FIG. In FIG. 3, the (S-1) high-frequency signal input to the RF signal input terminal 101 is as follows.
The distributor 103 distributes the same number as the propagation paths of the elementary waves (S-2) and enters the elementary wave propagation path simulating unit 104. In each system of the wave propagation path simulating unit 104, each high-frequency signal has a variable delay time generating circuit 105, 106, 107, a variable phase shifter 108, 109, 110 and a variable attenuator 111, 1.
Based on the control signal from the control unit 114, each of the element waves 12 and 113 undergoes a delay, a phase shift, and an attenuation received in the propagation path (S-3).

The high frequency signals of the respective systems output from the elementary wave propagation path simulating unit 104 are recombined by the combiner 119 in the same manner as the actual multiple wave propagation waves are recombined by the receiving antenna (S-
4) is output from the RF signal output terminal 120 (S-
5).

FIG. 4 shows the wave propagation path simulating unit 104 of this embodiment.
3 is a block diagram showing the configuration of one system of FIG. In the figure, a variable delay time generation circuit 403 is an A / D converter 40.
6, a FIFO memory 407, a D / A converter 408, a bandpass filter 409, and a delay control circuit 410. The delay control circuit 410 controls the delay time by outputting a control signal to the FIFO memory 407 and the D / A converter 408 based on the signal given from the control signal bus 402.

The signal input to the wave input terminal 401 is
The digital signal is converted by the A / D converter 406. This A / D conversion is performed at regular intervals by the clock signal output from the delay control circuit 410. The FIFO memory 407 accumulates the digital signal output from the A / D converter 406 and delays the digital signal by a control signal output from the delay control circuit 410 in order from the old digital signal and outputs the delayed digital signal.

The delayed digital signal is D / A
It is converted into an analog signal by the converter 408. Unwanted frequency components in the analog signal generated by digital conversion are attenuated by the bandpass filter 409.

The variable phase shift circuit 404 is a voltage controlled phase shifter 41.
1 and a D / A converter 412. The voltage control phase shift circuit 411 outputs the signal obtained from the control signal bus 402 to D /
The phase shift amount is controlled by the voltage obtained by the A conversion.

The variable attenuation circuit 405 comprises a PIN diode attenuator 413 and an attenuation controller 414. Attenuation controller 4
14 is a signal obtained from the control signal bus 402.
By changing the bias of the IN diode attenuator 413,
Control the amount of attenuation.

The variable delay time generation circuit 403 described above,
The variable phase shift circuit 404 and the variable attenuation circuit 405 can change the delay time, the amount of phase shift, and the amount of attenuation with time by a control signal.

As described above, similarly to each elementary wave in the actual multiple wave propagation path, the distributed signal of each system is delayed according to time,
Since the multipath propagation path is simulated by receiving the phase shift and attenuation, the situation close to the real propagation path can be realized in the laboratory experiment.

[0032]

As described above, since the propagation path simulating device of the present invention simulates the multiple wave propagation path by changing the propagation paths of the elementary waves forming the multiple wave propagation path, There is an advantage that it is possible to evaluate the transmission quality when the spread of delay time and the phase shift change with time by laboratory experiments.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the control unit of the embodiment.

FIG. 3 is a flowchart showing signal processing according to an embodiment.

FIG. 4 is a block diagram showing a configuration of one system of a wave propagation path simulating unit of the embodiment.

FIG. 5 is a block diagram showing an example of the configuration of a conventional channel simulation device.

[Explanation of symbols]

100 signal generator 101, 501 RF input terminal 102 control unit input terminal 103, 503 distributor 104 wave propagation path simulation unit 105, 106, 107, 403 variable delay time generation circuit 108, 109, 110, 404 variable phase shift circuit 111, 112, 113, 405 Variable attenuation circuit 114 Control part 115 Parameter input device 116 Calculation processor 117 Memory 118 Control signal output device 119, 509 Combiner 120, 513 RF output terminal 401 Elementary wave input terminal 402 Control signal bus 406 A / D converter 407 FIFO memory 408, 412 D / A converter 409 Band pass filter 410 Delay controller 411 Voltage control phase shifter 413 PIN diode attenuator 414 Attenuation controller 415 Rayleigh fading generator 504 90 Degree phase shifter 505,506 Gaussian noise generation circuit 507,508 Mixer 510,512 Amplifier 511 Delay time generation circuit

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[Procedure amendment]

[Submission date] August 12, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

These control data are sent to the control signal output device 11
8 is output to the wave propagation path simulating unit 104 according to time (S-6). Finally, when the measurement ends and the control stop signal is input from the signal generator 100 to the control unit input terminal 102 (S-7), the output of the control signal is stopped (S-8).

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

Claims (1)

[Claims] 1. A distribution circuit for distributing an input signal to a plurality of systems, a plurality of conversion circuits for changing the delay time, level and phase of each of a plurality of output signals of the distribution circuit, and the conversion circuit. A synthesis circuit for synthesizing all the output signals, and a control circuit for controlling the delay time, level, and the amount of change in phase of each of the conversion circuits, wherein the control circuit includes the delay time, level of each of the conversion circuits. And a propagation path simulation device characterized in that the amount of change in phase is changed with the passage of time.