JPH01292277A - System for detecting position of moving body - Google Patents

Abstract

PURPOSE:To easily detect the position of a moving transmission source with high accuracy, by performing measurement, such that the direction of the transmission source of a radio wave is measured on the basis of the level of a radio wave arriving within the shortest time and the directional characteristic of an antenna, at two or more places. CONSTITUTION:A modulated ratio wave is transmitted from a moving station 3. The direct wave 1 and reflected wave 2 received by directional antennas 4, 5, 6 are demodulated by receivers 10, 11, 12 and subsequently further subjected to correlation detection by correlation detectors 14, 15, 16. Only the radio wave arriving within the shortest time among the detected radio waves is measured by a level comparator 17. The direction of a radio wave transmission source is detected on the basis of said detected level and the directional characteristics of the antennas 4, 5, 6. The same measurement is performed at two or more places to detect the position of the radio wave transmission source.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for detecting the position of a mobile object such as a mobile station in a mobile communication system, and in particular to a method for detecting the position of a mobile object existing in a multiwave propagation path. It concerns the method of detection.

[Conventional technology]

FIG. 5 is a diagram showing the basic principle of the moving body position detection method.

In the figure, 51 and 52 represent directional antennas, and 53 represents a mobile station.

The radio waves transmitted from the mobile station 53 are transmitted to the directional antenna 51.
52, and direction θ1.52 in which the reception level is maximum. θ2
The position of the mobile station 53 is detected using a triangulation method.

In FIG. 5, in order to improve position detection accuracy, it is necessary to precisely measure the arrival direction of radio waves.

Figure $6 is a diagram showing a conventional actual method of measuring the arrival direction of radio waves.

In the figure, 63 is a mobile station, 64 . 65.66 are directional antennas, 67. 68°69 represents the radiation pattern corresponding to each antenna. Also,? 0
, 71, 72 indicate receivers connected to each antenna. 73 is a reflector such as a building.

In FIG. 6, radio waves transmitted from a mobile station 63 are transmitted through directional antennas 64 . 65, the level of which is proportional to the radiation pattern 67.68.

That is, due to the difference in the reception levels at the receivers 10.11, the radio waves from the mobile station 63 have a radiation pattern 67. 68 (Reference: Nakanari, et al.: ``Multi-beam base station antenna VI construction method and propagation characteristics'', 1932)
0th Annual National Conference of the Institute of Electronics and Communication Engineers, S5-16. (see J).

[Problem to be solved by the invention]

In the conventional method of detecting the position of a moving object as described above,
For example, in the case of the method shown in FIG. 6, in urban areas, the radio waves from the mobile station 63 are not only direct waves shown by solid lines (
, it may be reflected by a building 73 or the like around the mobile station and enter the radiation pattern 69 or 67.68 as shown by the dotted line.

In this case, receive @10. 71. The reception level of the mobile station 72 is a composite level of the direct wave and the reflected wave, which has the disadvantage that the direction of the mobile station 63 cannot be estimated correctly.

In view of these conventional problems, it is an object of the present invention to provide a mobile object position detection method that can detect the position of a mobile object with good accuracy even in the multi-wave propagation path as described above. The purpose is

[Means to solve the problem]

According to the present invention, the above object is achieved by the means described in the claims.

That is, the present invention is a method for detecting the position of a movable radio wave transmission source, and when the radio waves transmitted from the transmission source are reflected by surrounding features and received as multiple waves, the multiple waves are detected. The method is to perform similar measurements at multiple locations by separating radio waves using the difference in time of arrival at the measurement location, detecting the direction of the radio wave source based on the level of the radio wave that arrived in the shortest time and the directivity characteristics of the antenna. This is a mobile object position detection method that detects the location of the source of radio waves.

〔Example〕

FIG. 1 is a diagram explaining the principle of detecting the direction of a radio wave source according to an embodiment of the present invention, in which 1 is a direct wave, 2 is a reflected wave, 3 is a mobile station, and 4 to 6 are directivity waves. 10-12 are receivers, 13 is a reflector such as a building, 14-16 are correlation detectors, and 17 is a level comparator.

In the figure, a mobile station 3 transmits radio waves modulated with a PN code. The direct wave 1 and the reflected wave 2 received by the directional antennas 4, 5.6 are sent to the receiver 10. 11. After being subjected to II modulation at 12, correlation detection is further performed by correlation detectors 14, 15, and 16 using the same PN code as used in the mobile station 3.

Incidentally, the mutual detection shifts the bit by one bit each time the correlation between PN codes is taken, so that an output as shown in FIG. 2 is obtained.

In Figure @2, the direct wave is at the position τ1, and the reflected wave is at the position τ2.
The amplitude elf~e23 is output to the mobile station 3.
Radiation pattern for each incoming wave level from? , 8. 9
corresponds to each level when received.

That is, since the level τ in FIG. 2 is the reception level of the direct wave, the level comparator 17 measures only the level τ.

That is, by using elf l +21613, it is possible to detect the direction of a moving object in the same manner as in the case where there is no reflected wave even in the presence of multiple waves.

FIG. 3 is a diagram illustrating the principle of detecting the direction of a radio wave source according to another embodiment of the present invention.

In the same figure, 3. 10. 14. 17 is the same as in the +5i figure, 18 is an antenna rotating table, 19 is an antenna control unit, and 20 is a memory.

11.21' represents an antenna, and 22.22' represents a radiation pattern.

In the figure, the antenna 21 is attached to the antenna rotating table 18, and is rotated by a constant angle in response to a control signal from the antenna control section 19, and moved to the position shown at 21'. As a result, the radiation pattern 22 also moves to the position shown at 22'.

On the other hand, the antenna control unit 19 measures the level of radio waves at each angle using the level comparator 17 at +71 when the antenna 21 rotates by a certain angle.

The memory 20 records the output from the level comparator 17 and detects the direction of the mobile station 3 from the level at each angle of the antenna 9.

In other words, the method shown in Figure m1 required multiple antennas and receivers, but in this method, by rotating the antenna 21, the same function as using multiple receivers can be achieved. There is.

Note that as the antenna 21, it is also possible to use a 7-ray antenna.

As shown in Figure ff14, the reception system with the configuration shown in Figure 1 can be used as a conventional method by moving the measurement location and measuring the direction of the mobile body when multiple stations or a mobile body has stopped for a long time. Even in cases where many ghosts (23a to 27d) occur in the above method and the actual position is unclear, it is possible to distinguish between the actual position of the moving object and the ghost, allowing highly accurate moving object position detection. can be realized.

Note that the radio waves transmitted from the mobile station 3 only need to be able to measure the delay time of multiplexed waves, and the same effect can be obtained by using, for example, a pulse signal instead of radio waves modulated with a PN code.

Regarding the above correlation detection, see the document [D.

C, Cox: “D 1stribution
of multipath delay 5pread
and average excess delay
ror9 1 0 - MHz urban m
obile radio patl+s ″ heavy I
EEE Trans, Ant, Prop, V
ol, AP-23t No, 2 pp, 206-
213.4.

[Effect of the invention 3] As explained above, according to the method of the present invention, even in places where there are many reflected waves such as urban areas, it is possible to locate sources of radio waves that may move, such as mobile stations. It has the advantage of being easy to detect with high precision.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the principle of detecting the direction of a radio wave source according to an embodiment of the present invention, FIG. 2 is a diagram showing an example of separating and measuring multiple waves, and FIG. 3 is a diagram illustrating another embodiment of the present invention. A diagram explaining the principle of detecting the direction of a radio wave source in an embodiment, FIG. 4 is a diagram showing a configuration for detecting the position of a radio wave source in an embodiment of the present invention, and FIG. 5 is a diagram showing the position of a moving object. A diagram showing the basic principle of the detection method,
FIG. 6 is a diagram showing a conventional method of measuring the arrival direction of radio waves. 1 ・・・・・・Direct wave, 2 ・・・・・・
Reflected wave, 3...Mobile station, 4-6...
...Directional antenna, 7-9 - Old...
Radiation pattern, 10-12...Receiver,
13...Reflector, 14-16
...Correlation detector, 17 ...Level ratio 11ffi device, 18 ...Antenna rotating table, 19 ...Antenna control section, 20
・・・・・・ Memory, 21.21' ・・・
...antenna, 22. 22'...
・Radiation pattern, 23a to 21d...
・Ghost agent Patent attorney Takashi Honma Figure 1, 3@

Claims (1)

[Claims] This method detects the location of a movable radio wave source, and when the radio waves sent from the source are reflected by surrounding features and received as multiple waves, the method detects the location of the multiple waves before they arrive at the measurement location. The direction of the source of the radio wave is detected by separating it using the time difference, the level of the radio wave that arrived in the shortest time, and the directivity characteristics of the antenna, and by making similar measurements at multiple locations. A mobile object position detection method characterized by detecting the position of.