JPH11136745A - Mobile communication system and method for stabilizing its service area - Google Patents

Abstract

(57) [Summary] [Problem] To always secure a stable service area even if the weather environment changes. SOLUTION: A receiving antenna 20 provided at an edge portion of a wireless zone 40 and an electric field strength monitoring receiver 22 connected thereto receive a transmission wave 48 output from a base station antenna 30 and receive the electric field. Detect intensity. The received electric field strength information corresponding to the electric field strength of the transmission wave 48 is sent to the radio base station 10 via the transmission line 24 and the radio base station 1
The transmission power is variably controlled by each transmission power variable transmitter 12, 14, 16, 18 within 0. In the control, the transmission power of the transmission power variable transmitter 12 is feedback-controlled so that the electric field intensity input to the electric field intensity monitoring receiver 22 is always constant, and further the other transmission power variable transmitters 14 and 1 are controlled.
Outputs 6 and 18 are similarly controlled. As a result, a wireless zone having a stable size, that is, a service area A can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system and a method for stabilizing a service area thereof, and more particularly, to a mobile communication system using quasi-millimeter wave or millimeter wave charged wave and its service area. To a method for stabilizing.

[0002]

2. Description of the Related Art At present, mobile communication systems for outdoor services using quasi-millimeter waves or millimeter waves are being studied for practical use. The radio wave propagation characteristics of these quasi-millimeter wave or millimeter wave charged waves are "strong in straightness", "easy to shield radio waves", and "compared to the characteristics of VHF band and UHF band generally used conventionally." Due to such properties as "high propagation loss", application development to various kinds of sensing, air pollution monitoring, and the like using a millimeter-wave radar that effectively utilizes these properties is active. On the other hand, as an application to the field of wireless communication, a fixed (semi-fixed) point-to-point relay line has been conventionally put into practical use.
In addition to the communication system, the practical use of a point-multipoint mobile communication system forming one or a plurality of wireless zones is under study. For example, FIG. 2 shows a conceptual diagram of a service area based on a conventional wireless zone using quasi-millimeter waves or millimeter-wave charged waves. In this example, the configuration of a wireless zone in which one service area is divided into four sectors is shown. It is shown. The conventional mobile communication system shown in FIG.
Wireless transmitters 5 for each wireless zone respectively arranged in
2, 54, 56, and 58; antennas 60, 62, 64, and 66 for outputting a transmission wave to each wireless zone; and a wireless transmitter 52 and an antenna 6 under normal weather conditions.
0, a wireless zone 70 formed by the electric field strength of the transmitted wave output from the wireless transmitter 54, and similarly, a wireless zone 72 formed by the electric field strength of the transmitted wave output from the wireless transmitter 54 and the antenna 62. A wireless zone 74 formed by the electric field strength of the transmission wave output from the wireless transmitter 56 and the antenna 64 and a wireless zone 76 formed by the electric field strength of the transmission wave output from the wireless transmitter 58 and the antenna 66. is there.

A reduced radio zone 80 of a radio zone 70 caused by an increase in propagation loss of a transmission wave output from an antenna 60 due to a change in weather environment. The reduced radio zone 82 of the radio zone 72 caused by the increase in the propagation loss, the reduced radio zone 84 of the radio zone 74 caused by the increase in the propagation loss of the transmission wave output from the antenna 64, and the transmission wave output from the antenna 66 There is a reduced wireless zone 86 of the wireless zone 76 that results from increased propagation loss. And
The service area A is a wireless zone 7 where the weather environment is normal.
0, 72, 74 and 76, and the reduced service area B is constituted by the wireless zones 80, 82, 84 and 86 when the weather environment changes and the propagation loss increases. It is assumed that a mobile terminal device 88 is arranged between A and the reduced service area B.
In the conventional mobile communication system configured as described above, in a normal weather environment, as long as the mobile terminal device 88 moves inside the service area A, there is no insensitive area, and the electric field strength of a certain level or higher is not generated. As a result, communication with the wireless base station 50 was normally performed.

[0004]

However, in such a conventional mobile communication system, a quasi-millimeter wave or a millimeter wave band is used for forming a radio zone.
Variations in propagation loss increase with changes in the weather environment such as rain, snow, fog, haze, and smog. When the weather environment changes and the propagation loss of the transmission wave output from the antenna increases as shown in FIG. 2, the service area A is reduced like the reduced service area B as shown in FIG. When an insensitive area (area between the service area A where the mobile terminal device 88 is disposed and the reduced service area B) where the electric field level or less is generated and the mobile terminal device 88 enters the insensitive area, Service area A
However, there is a disadvantage that communication cannot be performed even within the inside. In addition, even if a certain service area is covered by a plurality of wireless zones, if the size of each wireless zone changes due to the weather environment,
Since a gap may be generated at an edge portion to be covered in each wireless zone, there is a disadvantage that a service area formed by an original zone configuration is disturbed. The present invention has been made in view of the disadvantages of the related art, and an object of the invention described in claim 1 is to ensure a service area of a constant size even when the weather environment changes. It is to provide a mobile communication system. An object of the invention described in claim 2 is to provide a mobile communication system capable of stabilizing a service area at low cost even if the service area includes a plurality of wireless zones. It is an object of the present invention to provide a method for stabilizing a service area of a mobile communication system, which can always secure a service area of a fixed size even when the weather environment changes.

[0005]

According to a first aspect of the present invention, there is provided a mobile unit which forms a service area in which wireless communication is possible in accordance with the electric field strength of a transmission wave output from a wireless base station via a base station antenna. In a communication system, transmission wave reception means for receiving a transmission wave output from the base station antenna, electric field intensity detection means for detecting the electric field intensity of the transmission wave received by the transmission wave reception means, and the electric field intensity detection Transmission power variable transmission means for variably controlling the output of the transmission wave output to the base station antenna based on the reception electric field strength information detected by the means, and the electric field of the transmission wave received by the transmission wave reception means. The output of the transmission wave is controlled by the transmission power variable transmission means so that the intensity is always constant. According to this, the transmission wave output from the base station antenna is received by the transmission wave reception means, the electric field strength of the transmission wave received by the transmission wave reception means is detected by the electric field intensity detection means, and the reception electric field strength information is obtained. Because the output of the transmission wave output to the base station antenna is variably controlled by the transmission power variable transmission means so that the electric field strength of the transmission wave received by the transmission wave reception means is always constant based on the The size of the service area can always be kept constant even if the propagation loss of the transmission wave changes with the change. According to a second aspect of the present invention, in the mobile communication system according to the first aspect, the service area includes a plurality of wireless zones formed by the wireless base station and a plurality of base station antennas. The transmission wave receiving means and the electric field strength detection means are provided in a specific wireless zone in the plurality of wireless zones, based on the received electric field strength information in the specific wireless zone, other than the specific wireless zone other than The output of the transmission wave in the wireless zone is controlled. According to this, when a service area is configured by a plurality of wireless zones formed by a wireless base station and a plurality of base station antennas, the transmission wave receiving unit and the electric field strength detecting unit are connected to a plurality of wireless zones. It is provided in the specific wireless zone inside and controls the output of the transmission wave of the wireless zone other than the specific wireless zone based on the received electric field strength information in the specific wireless zone, thereby stabilizing the service area at low cost. Can be realized. According to a third aspect of the present invention, there is provided a method for stabilizing a service area of a mobile communication system which forms a service area in which wireless communication is possible according to the electric field strength of a transmission wave output from a wireless base station via a base station antenna. A detecting step of detecting a reception electric field strength of a transmission wave output from the base station antenna, and based on the reception electric field strength information of the detected transmission wave, the base station so that the reception electric field strength is always constant. Controlling the output of the transmission wave output from the station antenna by feedback control. According to this, the reception electric field strength of the transmission wave output from the base station antenna is detected, and based on the reception electric field strength information of the detected transmission wave, the base station antenna is controlled so that the reception electric field strength is always constant. By performing feedback control on the output of the transmission wave output from, the size of the service area can always be kept constant even if the propagation loss of the transmission wave fluctuates with changes in the weather environment.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to FIG. FIG. 1 is a schematic configuration diagram of a mobile communication system according to the present embodiment, and here shows a service area based on a wireless zone using quasi-millimeter waves or millimeter waves. The service area A shown in FIG. 1 is configured by a wireless zone divided into four sectors. The mobile communication system in FIG. 1 is arranged in a radio base station 10 and in the radio base station 10, and changes transmission power based on reception field strength information output from a field strength monitoring receiver 22 described later. Variable transmission power transmitter 1 for each wireless zone
2, 14, 16, 18; a receiving antenna 20 for receiving a transmission wave in a specific wireless zone;
The electric field intensity monitoring receiver 22 monitors the electric field intensity of the transmission wave received at 0, and the received electric field intensity information of the transmission wave in the specific wireless zone output from the electric field intensity monitoring receiver 22 is transmitted to each transmission power variable transmitter 12, A transmission line 24 for transmitting the signals to the wireless communication zones 14, 16, and 18, and base station antennas 30, 32, 34, and 36 for outputting a transmission wave to each wireless zone are provided.
The wireless zone 40 is formed by the electric field strength of the transmission wave output from the variable transmission power transmitter 12 and the base station antenna 30, and the wireless zone 42 is defined by the variable transmission power transmitter 14 and the base station antenna 32. The wireless zone 44 is formed by the electric field strength of the output transmission wave, the radio zone 44 is formed by the electric field strength of the transmission wave output by the transmission power variable transmitter 16 and the base station antenna 34, and the radio zone 46 is formed by the transmission power variable This is formed by the electric field strength of the transmission wave output from the transmitter 18 and the base station antenna 36.
Then, the transmission wave 4 output from the antenna 30 in FIG.
Reference numeral 8 denotes a transmission wave composed of a quasi-millimeter wave or a millimeter wave band radio wave.

[0007] The operation of the mobile communication system of the present embodiment configured as described above will be described below. The receiving antenna 20 shown in FIG. 1 is installed beforehand at the edge of the wireless zone 40. And the radio base station 10
The transmission power variable transmitter 12 has a wireless zone 40 formed by outputting a quasi-millimeter wave or millimeter wave band transmission wave 48 from the base station antenna 30, and as described above, the other wireless zones 42, 44 and 46 are similarly formed. The receiving antenna 20 provided at the edge of the wireless zone 40 and the electric field intensity monitoring receiver 22 connected thereto receive the transmission wave 48 output from the base station antenna 30 and detect the electric field intensity. I do.
Then, the electric field intensity monitoring receiver 22 sends the received electric field intensity information according to the electric field intensity of the received transmission wave 48 to the wireless base station 10 via the transmission line 24. Wireless base station 10
Each of the variable transmission power transmitters 12, 14, 16, and 18 controls the transmission power variably based on the received electric field strength information described above. In the present embodiment, as described above, variable transmission power transmitter 12 transmits base station antenna 30
A transmission wave 48 output through the wireless transmission path is received by the receiving antenna 20 via the wireless transmission path, and reception electric field strength information obtained by the electric field strength monitoring receiver 22 is input to the transmission power variable transmitter 12. It is composed of For this reason, when the weather environment changes and the loss of the radio transmission path of the transmission wave 48 of the quasi-millimeter wave or the millimeter wave charged wave fluctuates, the degree of the influence can be obtained as the received electric field strength information. Even if the environment changes, the transmission power variable transmitter 12 is controlled so that the input electric field to the electric field strength monitoring receiver 22 (that is, the output level of the receiving antenna 20) is always constant.
, It is possible to always form a wireless zone 40 having a fixed size.

In the present embodiment, the received electric field intensity information output from the electric field intensity monitoring receiver 22 with reference to the wireless zone 40 is transmitted to the transmission power variable transmitters 14, 16 and 18 via the transmission line 24. By supplying them in parallel to each other and controlling the outputs of the transmission power variable transmitters 14, 16, and 18 in the same manner, the other wireless zones 42, 44, and 46 have stable sizes that are not affected by changes in the weather environment. Zone can be formed. as a result,
The service area composed of these stable wireless zones can be similarly stabilized. As described above, according to the present embodiment, in a mobile communication system using quasi-millimeter wave or millimeter wave band transmission waves, even if the weather environment changes and the electric field strength of the transmission waves fluctuates, Since the size of the wireless zone can be kept constant, the service area can be stabilized and a good communication environment can be obtained. Further, the receiving antenna and the electric field strength monitoring receiver used in the present embodiment do not need to be installed in all wireless zones, but only need to be installed in a specific wireless zone. It can be realized at cost. Here, each of the wireless zones 40, 42,
The diameter of the service area A composed of 44 and 46 has been described assuming a size of about several hundred meters, but is not limited to this, and is of course not limited to this, and a wider service area or a narrower service area is described. The same applies to service areas within a range. Although the configuration in the radio base station 10 shown in FIG. 1 actually includes various components, signal lines, and the like, illustration and description of portions that are not directly related to the description of the present embodiment are made. Has been omitted. Furthermore, in the above-described embodiment, the installation location of the receiving antenna 20 has been described as the edge portion of the wireless zone 40, but the installation location of the receiving antenna 20 is not limited to this edge portion. If the electric field strength at the edge can be estimated,
Any location may be used. Further, in the above embodiment, one service area A is divided into four wireless zones 40,
Although the description has been given of the case where the wireless network is configured with 42, 44 and 46, the number of wireless zones configuring the service area is not limited to this.

[0009]

As described above, according to the first aspect of the present invention, a stable service area having a constant size can be always secured even when the weather environment changes. According to the second aspect of the present invention, even if the service area includes a plurality of wireless zones, the service area can be stabilized at low cost. According to the third aspect of the present invention, a stable service area having a constant size can be always secured even when the weather environment changes.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a mobile communication system according to the present embodiment.

FIG. 2 is a schematic configuration diagram of a conventional mobile communication system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Radio base station 12, 14, 16, 18 Transmission power variable transmitter (transmission power variable transmission means) 20 Receiving antenna (transmission wave receiving means) 22 Electric field intensity monitoring receiver (electric field intensity detection means) 24 Transmission path 30, 32, 34, 36 Base station antennas 40, 42, 44, 46 Wireless zone 48 Transmitted waves

Claims (3)

[Claims] 1. A mobile communication system that forms a service area in which wireless communication is possible according to the electric field strength of a transmission wave output from a wireless base station via a base station antenna, wherein the transmission output from the base station antenna is provided. Transmission wave receiving means for receiving a wave, electric field strength detection means for detecting the electric field strength of the transmission wave received by the transmission wave reception means, and said electric field strength information based on the reception electric field strength information detected by said electric field strength detection means. Transmission power variable transmission means for variably controlling the output of the transmission wave output to the base station antenna, wherein the transmission power variable transmission is performed such that the electric field intensity of the transmission wave received by the transmission wave receiving means is always constant. A mobile communication system characterized in that output of a transmission wave is controlled by means. 2. When the service area is constituted by a plurality of wireless zones formed by the wireless base station and a plurality of base station antennas, the transmission wave receiving means and the electric field strength detecting means are arranged so that: It is provided in a specific wireless zone of a plurality of wireless zones, and based on received electric field strength information in the specific wireless zone, controls output of a transmission wave of a wireless zone other than the specific wireless zone. The mobile communication system according to claim 1, wherein 3. A method for stabilizing a service area of a mobile communication system for forming a service area capable of wireless communication according to the electric field strength of a transmission wave output from a wireless base station via a base station antenna, A detection step of detecting the reception electric field strength of the transmission wave output from the station antenna, and based on the reception electric field strength information of the detected transmission wave,
A control step of performing feedback control on an output of a transmission wave output from the base station antenna so that a received electric field intensity is always constant. A method for stabilizing a service area of a mobile communication system, comprising: