JPH06284057A - Method for controlling antenna beam - Google Patents

Abstract

(57) [Abstract] [Purpose] Regarding an antenna beam control method of a mobile terminal used when transmitting information between a fixed station and a mobile terminal installed indoors, an obstacle is present in the propagation path between the fixed station and the mobile terminal. The purpose is to enable highly reliable information transmission even after entering. When an indoor fixed station and a mobile terminal having a transmitter 5 and a receiver 4 transmit information by radio waves, an antenna 6 that changes the direction of a main beam in response to an antenna control signal input to the mobile terminal is provided. Using the memory 2 in which the antenna control information is stored, the reception level monitoring means 3 for monitoring the reception level and transmitting the monitoring result, and the monitoring result and the antenna control information, the antenna control is performed according to a preset control procedure. The antenna control means 1 for generating / transmitting a signal is provided, and when the antenna control means recognizes from the input monitoring result that the arrival direction of the strongest radio wave is disturbed, the antenna control means 1 automatically It is configured to direct the main beam.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a fixed station provided in a room.
The present invention relates to an antenna beam control method for mobile terminals used when transmitting information between mobile terminals.

Currently, a LAN using a cable is used for indoor data communication, but the wiring of the cable must be changed when the layout is changed. Therefore, in order to easily add and relocate various terminals without performing special work for wiring, not only mobile devices used indoors, but also cordless data transmission systems for various information device terminals. Is expected to build a wireless communication network.

At this time, it is necessary to enable highly reliable information transmission even if an obstacle enters the propagation path between the fixed station and the mobile terminal.

[0004]

2. Description of the Related Art FIG. 8 is an explanatory view of a conventional example. In general,
In wireless communication in a radio wave propagation environment such as in a city, it is often difficult to determine the arrival direction of radio waves due to reflection, diffraction, scattering, etc. of radio waves from buildings, etc., and it is often treated as a Rayleigh fading environment. Therefore, an omnidirectional antenna is used.

On the other hand, when wireless communication is performed indoors, since the fixed station is in an environment where it can be seen, it is necessary to avoid the multipath caused by the radio waves transmitted from the fixed station being reflected on the floor, ceiling, and wall surfaces. , Means for increasing the antenna gain for the direct wave that is the desired wave by removing the directivity of the antenna beam on the terminal side and directing it toward the fixed station, and for removing the reflected wave that is the unwanted wave Can be considered.

This will be described with reference to FIG. As shown in the figure, for example, a fixed station is installed at a predetermined height in one of the rectangular rooms, and the antenna beam of the fixed station is omnidirectional in the horizontal plane so that the mobile terminal can receive it at any position. It has become.

Therefore, the radio wave transmitted from the fixed station is divided into a direct wave (in the figure) and a reflected wave (for example, in the figure) and propagates toward the mobile terminal, but the reception level at the mobile terminal propagates. The direct wave with the shortest distance is the highest, and the reflected wave is lower than the direct wave due to the longer propagation distance and the loss of the reflection point than the direct wave.

Further, when the directivity of the mobile terminal antenna is as shown by the dotted line, the reflected wave is suppressed by the difference in antenna gain compared to the direct wave, and the reflected wave is suppressed to the extent that it has almost no effect. It That is, the sharper the directivity of the antenna, the more the reflected wave can be suppressed.

[0009]

However, if an obstacle such as a person enters between the fixed station and the mobile terminal due to its directivity, the propagation of radio waves is blocked by the obstacle, making it difficult to transmit information. However, there is a problem that reliable information transmission cannot be performed.

An object of the present invention is to enable highly reliable information transmission even if an obstacle enters the propagation path between a fixed station and a mobile terminal.

[0011]

FIG. 1 is a block diagram showing the principle of the first to sixth aspects of the present invention. In the figure, 6 is an antenna that changes the direction of the main beam in response to an input antenna control signal,
Reference numeral 2 is a memory in which antenna control information is stored, 3 is a reception level monitoring means for monitoring a reception level and sending out a monitoring result, 1 is an antenna according to a preset control procedure using the monitoring result and the antenna control information. Generate control signal
It is an antenna control means for transmitting.

According to the first aspect of the present invention, when the antenna control means recognizes from the input monitoring result that the arrival direction of the first strongest radio wave (direct wave) is disturbed, the antenna control means automatically The main beam was directed to the arrival direction of the second strongest radio wave (reflected wave).

In the second aspect of the present invention, the above control procedure directs the main beam in the direction of arrival of the first to second strongest radio waves due to interference, but when the second is also disturbed, it is the first strongest. Return the main beam to the direction of arrival of the radio wave, but if the first one continues to be disturbed, direct the main beam to the direction of arrival of the radio wave with decreasing intensity within the range where the set reception level can be secured. I chose

In a third aspect of the present invention, when the above control procedure directs the main beam to the arrival direction of the radio wave of the second and subsequent strengths, the direction of the stronger radio wave arrives at the time when no information is transmitted. The main beam was directed to check for interference, and the main beam was directed to the direction of the strongest radio wave in the direction of arrival where interference was eliminated.

According to a fourth aspect of the present invention, the antenna control information predicts the arrival directions of the direct wave and at least one reflected wave from the room size, position, material, mobile terminal position, and fixed station position. It is composed of the calculated arrival direction of the radio wave and the corresponding reception level.

In a fifth aspect of the present invention, the above antenna control information indicates a reception level measured by scanning the main beam in a predetermined direction during a period other than when the system is in operation and a corresponding arrival direction of a radio wave. Constitute.

According to a sixth aspect of the present invention, the difference between the reception levels when the direct wave and the reflected wave are received by the main beam is calculated or actually obtained and stored as level difference data in a predetermined area of the above memory.

Further, the above-mentioned antenna control means, when transmitting information to and from the fixed station by using the reflected wave, so as to maintain a predetermined transmission quality, the corresponding level difference extracted from the memory. The data is used to adjust the gain of the transmitter and the receiver.

[0019]

Although it is very difficult to determine the arrival direction of radio waves in wireless communication such as in the city, in wireless communication indoors, room dimensions, wall material, fixed station position (coordinates), mobile terminal It is possible to calculate not only the direct wave but also the reflected wave, the direction of arrival, the attenuation level of the radio wave, etc., from the position, the directivity of the antenna, and the like.

Therefore, these calculation data are stored in advance in the memory as the antenna control information in terms of the angle of arrival of radio waves (azimuth angle and elevation angle) and reception level in strong order using the reception level as an index. At this time, it is assumed that the fixed station transmits using an antenna pattern used, for example, an antenna that is omnidirectional in the horizontal direction, and the mobile terminal receives using a spherical pattern antenna.

Further, since the monitoring result is constantly sent from the reception level monitoring means to the antenna control means, when the antenna control means recognizes that the monitoring result is lower than the set value, it follows a predetermined control procedure. A control signal for changing the direction of the main beam to a predetermined direction is sent to the antenna. This makes it possible to prevent interruption of information transmission by switching the main beam when some kind of failure occurs in the propagation path between the fixed station and the mobile terminal.

Further, since the attenuation level of the radio wave can be predicted in the above calculation, for example, when the beam is directed from the direct wave to the reflected wave, the gains of the transmitter and the receiver are adjusted. The transmission / reception level can be raised to a level at which information can be transmitted.

It should be noted that the reception level is measured, not calculated,
It is also possible to store the scanning direction of the antenna main beam and the reception level as actual measurement data, and store them in order of strong radio waves.

[0024]

FIG. 2 is a block diagram of the first to sixth embodiments of the present invention, FIG. 3 is a block diagram of the essential parts of the antenna control section in FIG. 2, and FIG.
5A and 5B are illustrations of antenna control information calculation used in the embodiment of the present invention, FIG. 5A is an example of indoor arrangement, FIG.
3A and 3B are explanatory views of actual measurement of antenna control information used in the embodiment of the present invention, FIG. 6A is a perspective view, and FIG. Further, FIG. 6 is an explanatory diagram of the control procedure used in the embodiment of the present invention (in the case of calculated antenna control information), and FIG. 7 is another explanatory diagram of the control procedure used in the embodiment of the present invention (in the case of measured antenna control information). ).

The antenna control unit 11 and the level control unit 1
2, the demultiplexer 13 is a component of the antenna control means 1, and the reception level detector 31 and the coupler 32 are components of the reception level monitoring means 3. Hereinafter, FIGS. 2 to 7 will be described.

First, as shown in FIG. 4 (a), when viewed from above, a fixed station is provided at the lower right of a rectangular room, and a mobile terminal is provided at the end in the middle of the left. Information was transmitted to and from the fixed station by directing the beam (ellipse dotted line in the figure) to the direct wave propagation path, but the direct wave propagation path due to obstacles such as people (shaded lines in the figure) If is blocked (you can see that the reception level drops below the specified value), as shown by the arrow,
Information transmission is continued by directing the main beam to the propagation path of the reflected wave expected in advance.

Here, in order to direct the direction of the main beam to the propagation path of the direct wave or the reflected wave, it is necessary to know the arrival directions of the respective waves in advance. This can be obtained by calculation or actual measurement as described below. You can <For calculation> The dimensions of the room in Fig. 4 (a) are 30m in width and 5 in depth.
Assuming that the height is 0 m and the height is 2.5 m, as shown in FIG. 4 (b), x, y,
Select a three-dimensional Cartesian coordinate system of z and set the coordinates (position) of the fixed station.
(24.5, 3.5, 1.8) and mobile terminal coordinates are (6, 30, 1.4) [unit is m], the direction of arrival of the direct wave is azimuth θ = -55.1 degrees, elevation φ = 0.71 degrees, reflection The direction of wave arrival can be calculated as azimuth θ = -139.0 degrees and elevation φ = 0.57 degrees. The same can be calculated for the propagation paths of other reflected waves. At this time, the propagation loss is also calculated, and the reception level corresponding to the arrival direction is stored in the memory as antenna control information. <In the case of actual measurement> In addition, in the case of actual measurement, the antenna beam is scanned when the mobile terminal is powered on / reset,
As shown in, the reception level of each coordinate of A ₁ → A ₂ → ・ ・ → B ₁ → B ₂ → ・ ・ is measured and stored in the memory as antenna control information together with the angle (azimuth angle, elevation angle) data. Fig. 5 (b) is a view of the diagram of Fig. 5 (a) seen from directly above. For example, point A ₁ is the direct wave and the reception level is maximum, point A ₂ is the reflected wave, and the reception level is the second highest. Point B ₃ is the third received level of the reflected wave, and these measured data are stored in the memory as antenna control information as in the above.

Further, as shown in FIG. 3, the antenna controller 11
Is a memory 22 in which antenna control information is stored, a CPU111,
It comprises a ROM 21, which stores the control procedure shown in FIG. 6 or FIG. 7, interfaces 114 and 115, and a phase shifter 62 which changes the main beam direction of the array antenna 61.

Next, the operation of FIG. 2 will be described with reference to FIG. When the switch is turned on, it checks whether the position of the mobile terminal or the material of the reflective object in the room has changed,
If there is a change, the changed parameter is used to recalculate the reception level, the direction of the main beam, and the like, and the result is stored in the memory in the antenna control unit 11.

Then, when the main beam of the antenna is directed in the direction of arrival of the direct wave (reception level is the first and highest) obtained in advance, the radio wave from the fixed station is received by the array antenna 61, the demultiplexer 13, the receiving section. 4, reception level detector 31 via coupler 32
Added to. The reception level detector 31 detects the reception signal and sends the detection result to the antenna control unit 11. Therefore, when the antenna control unit recognizes from the detection result that the reception level is substantially the predetermined value, the reception unit 4 and the transmission unit The gain of 5 is set to a predetermined value and information transmission is started between the fixed station and the mobile terminal (see FIG. 6-).

However, if the propagation path of the direct wave is blocked by an obstacle such as a person, the reception level drops below a predetermined value, and when the antenna control section 11 recognizes this, the reception level becomes the second direction. Aim the main beam. Further, when the propagation path in this direction is also damaged, the main beam is scanned in the direction in which the reception level becomes 1 → 3 → 4th, and the beam is fixed at a place where a predetermined level is obtained. Then, the nth (n ≧
3) When the direction after is damaged, 1 → 2 → ・ ・ → (n
-1) → (n + 1) → ... Scanning is carried out in this order, and the beam is fixed where a predetermined level is obtained (Fig. 6-,
See).

That is, if the upper reception level is less than or equal to a predetermined value, the main beam is directed to a direction lower than these, for example, the third direction, and in this state, the process returns to the "fault detection" step. If is restored to a predetermined value, the main beam is directed to the restored upper direction and the process similarly returns to the step of “fault detection” (see FIGS. 6-, ...).

It should be noted that, for example, when the main beam is directed to the third direction at the reception level, it is checked whether or not the first direction has become normal at a predetermined cycle during the period in which information transmission is not performed. If so, check the first, if not normal, check the second, and if not normal, return to the third.

When the main beam is directed in the direction in which the reception level is the third, the antenna control unit 11 can know the level difference from the case where the reception level is the first from the above antenna control information. A level control signal is sent to the level control unit 12 so that the level difference disappears. The level control unit controls the gains of the receiving unit and the transmitting unit so that even if the main beam is directed in the third direction, there is not much level difference as compared with the case of the first case.

Further, in the case of the control procedure shown in FIG. 7, for example, when the switch is turned on, the reception level and angle data of each point are measured and stored in the memory as described in FIG. The subsequent procedure is the same as in Fig. 6 (see Fig. 7-).

After all, even if an obstacle such as a person is present in the propagation path, a method of electronically switching the main beam in the direction of the propagation path having the next highest reception level based on the data calculated or measured in advance. Therefore, it is possible to deal with interference more flexibly than in the case where the beam is fixed, and there is no wasteful ante scanning compared to the direction in which all the directions are randomly scanned, and efficient beam switching ensures reliability. Higher information transmission is possible.

[0037]

As described above in detail, the present invention has an effect that highly reliable information transmission can be performed even if an obstacle enters the propagation path between a fixed station and a mobile terminal.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of first to sixth aspects of the present invention.

FIG. 2 is a configuration diagram of the first to sixth embodiments of the present invention.

3 is a main part configuration diagram of an antenna control unit in FIG.

FIG. 4 is an explanatory diagram of antenna control information calculation used in the embodiment of the present invention, (a) is an example of indoor arrangement, and (b) is a coordinate system explanatory diagram.

5A and 5B are explanatory views of actual measurement of antenna control information used in an embodiment of the present invention, in which FIG. 5A is a perspective view and FIG.

FIG. 6 is an explanatory diagram of a control procedure used in the embodiment of the present invention (in the case of calculated antenna control information).

FIG. 7 is an explanatory diagram of another control procedure used in the embodiment of the present invention (in the case of actually measured antenna control information).

FIG. 8 is an explanatory diagram of a conventional example.

[Explanation of symbols]

 1 Antenna Control Means 2 Memory 3 Reception Level Monitoring Means 4 Receiver 5 Transmitter 6 Antenna

Claims (6)

[Claims] 1. An indoor fixed station, a transmitter (5), and a receiver (4)
In a system in which information is transmitted between a mobile terminal and a mobile terminal that uses radio waves, the mobile terminal stores the antenna (6) that changes the direction of the main beam in response to the input antenna control signal and the antenna control information. Memory (2), the reception level monitoring means (3) for monitoring the reception level and transmitting the monitoring result, and the antenna control signal according to a preset control procedure using the monitoring result and the antenna control information. And an antenna control means (1) for generating / transmitting, when the antenna control means recognizes from the input monitoring result that the arrival direction of the first strong electric wave (direct wave) is disturbed, An antenna beam control method characterized in that the main beam is automatically directed to the arrival direction of the second strongest radio wave (reflected wave). 2. The above control procedure directs the main beam in the direction of arrival of the first to second strongest radio waves due to interference,
When the second one is also disturbed, the main beam is returned in the direction of arrival of the strongest radio wave, but if the first one is still disturbed, the strength will be increased sequentially within the range where the set reception level can be secured. The antenna beam control method according to claim 1, wherein the main beam is directed to the arrival direction of the radio wave in which the noise is reduced. 3. The control procedure as described above, when the main beam is directed to the arrival direction of radio waves of the second and subsequent strengths, the main beam is directed to the arrival direction of stronger radio waves when information is not transmitted. The antenna beam control method according to claim 1, wherein the presence / absence of interference is checked, and the main beam is directed to the direction of arrival of the strongest radio wave among the directions of arrival without interference. 4. The arrival of a radio wave, wherein the antenna control information is calculated by predicting the arrival directions of a direct wave and at least one reflected wave from the room size, position, material, mobile terminal position, and fixed station position. The antenna beam control method according to claim 1, comprising a direction and a corresponding reception level. 5. The antenna control information comprises a reception level measured by scanning a main beam in a predetermined direction and a corresponding arrival direction of a radio wave during a period other than during system operation. Antenna beam control method. 6. A predetermined area of the memory, wherein a difference between reception levels when a direct wave and a reflected wave are received by a main beam is calculated or obtained by actual measurement and stored as level difference data, and the antenna control described above is also performed. The means uses the corresponding level difference data extracted from the memory so as to maintain a predetermined transmission quality when transmitting information to and from the fixed station using the reflected wave. The antenna beam control method according to claim 1, wherein the gain of the unit is adjusted.