JPH11340885A - Antenna system for mobile radio communication and its switching method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna system for mobile radio communication and its switching method where diversity control is maintained satisfactorily, independently of a change in a propagation environment. SOLUTION: Antenna elements 1, 2 act as an antenna for a space diversity system. An element group consisting of antenna elements 1, 3 and/or an element group consisting of antenna elements 2, 3 acts as an antenna element of a polarized wave diversity system. The antenna elements 1-3 connect to a diversity element limit device 4, which is connected to an antenna control circuit 7 directly, via an antenna element changeover device 5. The antenna control circuit 7 discriminates which of the space diversity system or the polarized wave diversity system is used for the diversity system of the antenna elements and commands the discrimination result to the diversity element limit device 4. The diversity element limit device 4 connects two elements among the antenna elements 1-3 to the antenna element changeover device 5 to configure either of the space diversity system or the polarized wave diversity system, based on the command of the antenna control circuit 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna apparatus for mobile radio communication and a switching method thereof, and more particularly to an antenna apparatus for mobile radio communication performing data communication using radio waves and a switching method thereof.

[0002]

2. Description of the Related Art Office computers, printers,
With the development of the network environment of each device such as a facsimile machine, the use of a wireless printer buffer, a wireless LAN, or the like has promoted wireless communication between the devices in order to avoid complicated wiring work for each device. Most of these wireless devices use an almost omnidirectional antenna such that each wireless device becomes omnidirectional on a horizontal plane such as a dipole, and even those that perform diversity control using a plurality of antenna elements. The system is a two-element diversity system in which the number of elements is simply reduced to two, and the switching control of the antenna elements is very simple, in which one is switched to the other if it is bad.

[0003] In addition, due to an increase in the frequency of movement by portable terminals and the miniaturization of the portable terminals themselves, not only communication under a fixed environment on the same floor but also movement of mobile terminals. There is also an increasing need for communication while using the device and taking it outdoors. Diversity control is essential in such an environment in which communication during movement, or movement of a person or furniture existing during the movement without moving the equipment.

[0004]

However, the environment may change greatly from the viewpoint of radio propagation, such as moving from outdoors to indoors or from a wide place such as a hall to a narrow place such as a conference room. When moving, the appropriate diversity scheme also changes depending on the environment.

For example, in a narrow environment such as a conference room, the reflected wave from a wall or ceiling does not attenuate much the electric field strength.
Since only the polarization direction changes and reaches the receiving point, the polarization diversity system is effective. On the other hand, in outdoor communication, the level of the reflected wave is attenuated because the distance to the reflecting object is long, and particularly in communication using a high frequency band of GHz band or more, communication by the direct line of sight becomes dominant, and Diversity effect decreases.

[0006] As described above, even if only one diversity system is effective in one use environment, it is not necessarily effective when moved to another environment.

[0007] In the conventional wireless data communication system, the main purpose is to arrange wiring cables and to improve the work efficiency of layout change, and the actual use environment is fixed. Even with the system, the effect could be expected by designing it in consideration of the usage environment, but in recent years the further miniaturization and weighing of mobile terminals is not limited to simple layout freedom, Communication and changes in frequent communication environments are required, and the conventional diversity system has a problem that the effect can be exerted only in a specific environment.

It is an object of the present invention to provide a mobile radio communication antenna device capable of maintaining good diversity control irrespective of a change in a radio propagation environment and a switching method thereof.

[0009]

In order to achieve the above object, an antenna apparatus for mobile radio communication according to claim 1 is provided.
Two antenna element groups of a space diversity type antenna element group and a polarization diversity type antenna element group, or two antenna element groups of a directional diversity type antenna element group and a polarization diversity type antenna element group In the mobile radio communication antenna device provided with the above, the limiting means for limiting one of the two antenna element groups and the quality of a signal received by one of the limited antenna element groups are measured. Determining means for comparing the measured quality with a predetermined threshold value to determine whether the measured quality has degraded from a predetermined threshold value; When the threshold value is degraded from the threshold value, another one of the limited one antenna element group is selected. Comprising selection means for, and counting means for counting the frequency of selection of said selection means, said limiting means,
When the number of selections is large, or when only one of the limited one antenna element group is selected, the other antenna element group in the two antenna element groups is limited. I do.

A second aspect of the present invention provides the antenna apparatus for mobile radio communication according to the first aspect, wherein the quality is an electric field strength of the received signal.

According to a third aspect of the present invention, in the antenna apparatus for a mobile radio communication according to the first aspect, the quality is a bit error rate at the time of demodulation of the received signal. And

According to a fourth aspect of the present invention, there is provided the antenna apparatus for mobile radio communication according to any one of the first to third aspects, wherein one of the two antenna element groups is one of the two antenna element groups. One of the antenna elements
And one of the two antenna element groups is shared with one of the antenna elements of the other antenna element group.

According to a fifth aspect of the present invention, there is provided a method for switching an antenna device for mobile radio communication, comprising two antenna elements, a space diversity type antenna element group and a polarization diversity type antenna element group. In a method for switching an antenna device for mobile radio communication comprising two antenna elements of a group or a directional diversity scheme and an antenna element of a polarization diversity scheme, one of the two antenna element groups Limiting the element group, measuring the quality of a signal received by one antenna element in the one of the limited antenna element groups, and comparing the measured quality with a predetermined threshold value. Determining whether or not the quality has deteriorated below a predetermined threshold; and When the quality has deteriorated below the predetermined threshold value, there is provided a selecting means for selecting another one antenna element in the limited one antenna element group, and a counting means for counting the number of selections of the selecting means. The limiting means, when the number of selections is large, or when only one antenna element in the limited one antenna element group is selected, sets the other one of the two antenna element groups to the other one. It is characterized by being limited.

According to a sixth aspect of the present invention, in the method for switching an antenna apparatus for mobile radio communication, the quality is an electric field strength of the received signal. It is characterized by.

According to a seventh aspect of the present invention, there is provided a method for switching an antenna apparatus for mobile radio communication according to the fifth aspect, wherein the quality of the received signal is reduced by a bit error when demodulating the received signal. It is characterized by a rate.

According to a eighth aspect of the present invention, there is provided a method for switching an antenna apparatus for mobile radio communication according to any one of the fifth to seventh aspects, wherein the two antenna element groups are provided. , One of the antenna elements of one of the two antenna element groups is shared with one of the antenna elements of the other one of the two antenna element groups.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG.
FIG. 1 is a block diagram of a mobile communication antenna device according to a first embodiment of the present invention. The antenna elements 1 and 2 are each composed of a linearly polarized element having a dipole-like directivity (see FIG. 3) and are arranged in parallel with each other at a distance of about ４ wavelength or more, preferably about 約 wavelength. I have. This 2
By arranging the elements in parallel, an antenna of the space diversity system (see FIG. 4), and by orthogonally arranging the elements, an antenna of the directional diversity system (see FIG. 5).
Can work.

On the other hand, the antenna element 3 has an omnidirectional characteristic in a horizontal plane, and is arranged so that the polarization planes of the antenna elements 1 and 2 are orthogonal to each other. This element 3 and antenna element 1
Or the element group of the element 3 and the antenna element 2 functions as a polarization diversity type antenna. The respective element groups may be switched according to the determination of the antenna control circuit 7 described later.

In the following description, the configuration will be described as a configuration in which the antenna elements 1 and 2 are arranged in parallel to function as a space diversity type antenna (FIG. 4). The operation is the same in the case of FIG. 5).

The antenna elements 1 to 3 are connected to the diversity element limiting device 4, and the diversity element limiting device 4 is directly connected to the antenna control circuit 7 and to the antenna control circuit 7 via the antenna element switching device 5. . The antenna control circuit 7 determines whether to use the space diversity method or the polarization diversity method as the diversity method of the antenna element by a method described later, and instructs the diversity element limiting device 4 to make the determination. The diversity element limiting device 4 connects two of the antenna elements 1 to 3 to the antenna element switching device 5 to configure one of the space diversity system and the polarization diversity system based on a command from the antenna control circuit 4. (Limiting means).

The antenna element switching device 5 is also connected to an antenna control circuit 7 via a reception level judgment circuit 9 and to a radio device 8. The reception signal from the antenna element selected by the antenna element switching device 5 is sent to the reception level determination circuit 9 and the wireless device 8, and the reception level determination circuit 9 sets the electric field strength of the reception signal to a predetermined electric field threshold. Compare (determination means). When the reception level determination circuit 9 determines that the electric field strength of the received signal is equal to or less than the threshold value, the antenna control circuit 7 sends the antenna element used by the antenna element switching device 5 to the other antenna element by a method described later. (Switching means).

The antenna element switching device 5 is also connected to an antenna control circuit 7 via an element selection number storage unit 6. The element selection number storage unit 6 is configured to count and store the number of selections of the antenna element selected by the antenna element switching device 5 (counting means), and the antenna control circuit 7 stores the element selection number. Only one antenna element is selected based on the information stored in the unit 6 (the electric field strength of one antenna element is within an allowable range, but the electric field strength of the other antenna element is lower than a predetermined threshold value). When the frequency is low and the total time during which one of the antenna elements is selected is long, the number of times of switching the antenna elements (the number of times of selection) itself is frequent (the electric field strength of both antenna elements is lower than a predetermined threshold). (Low), a switching signal for switching the diversity system to be used is transmitted to the diversity element limiting device 4 (limiting means).

This is because, when only one antenna element is selected, in the radio propagation environment in which the radio apparatus is in use, the antenna element to be switched appropriately is biased to only one antenna element. In the case where it is determined that the middle diversity method is inappropriate, the switching to the other diversity element group is performed. In a radio propagation environment in use, it is determined that the diversity scheme in use is not suitable and switched to the antenna element group of the other diversity scheme.

Regarding the switching of the diversity system,
The diversity method used as the initial value is set to the polarization diversity method, and the antenna element is switched to the space diversity method as necessary. vice versa,
When switching the antenna elements 1 to 3, the diversity scheme used as an initial value may be set to the space diversity scheme, and the polarization scheme may be switched to the polarization diversity scheme as needed.

Further, a manual diversity switch 10 is connected to the antenna control circuit 7, and the diversity manual switch 10 can also arbitrarily switch the diversity system at the discretion of the user.

The transmission signal transmitted from the radio device 8 is transmitted from the antenna element that is currently selected by following the same route as when receiving.

According to the present embodiment, switching means for switching between a plurality of diversity antenna groups and switching means for switching between a plurality of antenna elements of each diversity antenna group are provided so that a user can control the radio propagation environment. From the means of manually switching the diversity system according to the change of the or the selection status of each antenna element in the antenna element group in the diversity system in use,
By having means for automatically judging the switching of the diversity system, for example, the reflected wave is not so much attenuated by walls or ceilings such as private rooms in buildings, and only the direction of polarization changes to reach the receiving point In environments such as this, communications are performed using the polarization diversity method, and when going outdoors, communication using direct waves with line of sight becomes dominant. This makes it possible to perform effective diversity control.

When the mobile radio communication device having the antenna device of the present embodiment is used in a relatively small indoor environment, the reflected wave from the wall or ceiling does not attenuate much, and only the direction of the polarized wave changes. Therefore, communication can be ensured by the polarization diversity system. Also, when you go out outdoors, communication can be secured by the polarization diversity method, so if you move to a point where communication is difficult to secure due to multipath fading, switch the diversity method to change the direction of polarization. Even if it is changed, improvement in communication quality cannot be expected because the reception level of the cross polarization component is low.

If the antenna control circuit 7 determines that communication cannot be secured by switching the antenna element, the diversity method is switched to the space diversity side. As a result, even at a point where the reception level is reduced due to fading, the reception level can be improved by switching the antenna element, so that communication can be ensured.

Even when returning indoors, the communication is continued as long as communication can be ensured by the space diversity method, but there are situations in which signals with different polarization directions are received due to short-distance multiple reflection on a wall or the like. When the number of antenna elements increases, it becomes difficult to secure communication by switching the antenna elements, and the diversity method is switched again by the determination of the antenna control circuit 7, so that communication can be performed by the polarization diversity method.

(Second Embodiment) FIG. 2 is a block diagram of a mobile communication antenna device according to a second embodiment of the present invention. The configuration and operation of each of the antenna elements 1 to 3, the diversity element limiting device 4, the antenna element switching device 5, the element selection count storage unit 6, and the antenna control circuit 7 are the same as those of the first embodiment of the present invention. Yes, their description is omitted, and only different points will be described below.

A radio device 8 is connected to the antenna element switching device 5, and the radio device 8 is connected to an antenna control circuit 7. The received signal from the antenna element enabled by the antenna element switching device 5 is transmitted to the wireless device 8. The radio device 8 counts the bit error rate at the time of demodulation of the received signal and compares the bit error rate with a predetermined threshold value (determination means). 7 sends a command to the antenna element switching device 5 to switch the used antenna element to the other antenna element in the same diversity system (selection means).

According to the present embodiment, the quality judgment means received by the used antenna element can be realized with a simple configuration.

In the first and second embodiments, the antenna type used for each diversity type antenna element includes, for example, a dipole antenna and a batch antenna, but is not limited thereto. That is, any electromagnetic wave capable of transmitting and receiving radio waves of a specific frequency may be used as long as it has a function as a radiation element.

As the means for determining the quality of the received signal, for example, the electric field strength level of the received signal, the value of the bit error rate at the time of data demodulation, etc. are mentioned, but the present invention is not limited to this. Any means may be used as long as it evaluates the quality of the received signal based on some criteria.

[0036]

As described above in detail, according to the antenna switching method for mobile radio communication according to the first aspect and the antenna switching method for mobile radio communication according to the fifth aspect, an antenna of a space diversity system is provided. Limit two antenna groups of the element group and the polarization diversity type antenna element group, or limit one of the antenna element groups in the two antenna element groups of the directional diversity type antenna element and the polarization diversity type antenna element group Measuring the quality of a signal received by one antenna element in the limited one of the antenna element groups, comparing the measured quality with a predetermined threshold value, and determining whether the measured quality is a predetermined value; It is determined whether or not the measured quality has deteriorated below a predetermined threshold value. When one other antenna element in the antenna element group is selected and the number of selections is large, or when only one antenna element in the limited one antenna element group is selected, the two antenna elements are selected. Since the other antenna element group in the group is limited, diversity control can be favorably maintained irrespective of changes in the wireless propagation environment.

According to the antenna apparatus for mobile radio communication according to the fourth aspect and the switching method of the antenna apparatus for mobile radio communication according to the eighth aspect, an antenna element of one of the two antenna element groups is selected. One of
Since one of the two antenna element groups is shared with one of the antenna elements of the other antenna element group, the number of antenna elements can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of a mobile communication antenna device according to a first embodiment of the present invention.

FIG. 2 is a block diagram of an antenna device for mobile communication according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of characteristics of a dipole element.

FIG. 4 is an explanatory diagram of a configuration of space diversity and polarization diversity.

FIG. 5 is an explanatory diagram of a configuration of directivity diversity and polarization diversity.

[Explanation of symbols]

 1 to 3 antenna elements 4 diversity element limiting device 5 antenna element switching device 6 element selection count storage unit 7 antenna control circuit 8 wireless device 9 element selection count storage unit 10 manual diversity switch

Claims (8)

[Claims] 1. An antenna element group of a space diversity scheme and an antenna element group of a polarization diversity scheme, or two antenna elements of a directional diversity scheme and an antenna element group of a polarization diversity scheme. In an antenna device for mobile radio communication including an antenna element group, a limiting means for limiting one antenna element group in the two antenna element groups, and a signal received by one antenna element in the limited one antenna element group. Determining means for measuring the quality of the signal, comparing the measured quality with a predetermined threshold value, and determining whether the measured quality has deteriorated below a predetermined threshold value; When the quality deteriorates below the predetermined threshold, the other one antenna in the limited one Selecting means for selecting the tenor element; and counting means for counting the number of selections of the selecting means, wherein the limiting means selects one antenna element when the number of selections is large or one of the limited one of the antenna element groups. An antenna device for mobile radio communication, wherein when only an element is selected, the other one of the two antenna element groups is limited. 2. The mobile radio communication antenna device according to claim 1, wherein the quality is an electric field strength of the received signal. 3. The mobile radio communication antenna apparatus according to claim 1, wherein the quality is a bit error rate at the time of demodulation of the received signal. 4. An antenna element of one of the two antenna element groups and one of the other antenna element groups of the two antenna element groups are shared. Claim 1
4. The antenna device for mobile radio communication according to any one of claims 1 to 3. 5. An antenna element group of a space diversity scheme and an antenna element group of a polarization diversity scheme, or two antenna elements of a directional diversity scheme and an antenna element group of a polarization diversity scheme. In the method for switching an antenna device for mobile radio communication including an antenna element group, the step of limiting one of the antenna element groups in the two antenna element groups includes the step of limiting one antenna element in the one of the limited antenna element groups. Measuring the quality of the received signal, comparing the measured quality with a predetermined threshold to determine whether the measured quality is degraded from the predetermined threshold, When the measured quality deteriorates below a predetermined threshold, the other in the limited one antenna element group Selecting means for selecting one antenna element; and counting means for counting the number of selections of the selecting means, wherein the limiting means is provided when the number of selections is large or when one of the limited one of the antenna element groups is selected. A method for switching an antenna apparatus for mobile radio communication, wherein when only one antenna element is selected, the other one of the two antenna element groups is limited. 6. The method according to claim 5, wherein the quality is an electric field strength of the received signal. 7. The method according to claim 5, wherein said quality is a bit error rate at the time of demodulation of said received signal. 8. An antenna element of one of the two antenna element groups and one of the other antenna element groups of the two antenna element groups are shared. Claim 5
8. The method for switching an antenna device for mobile radio communication according to any one of claims 1 to 7.