JP2008154278A - Base station, antenna control method, and antenna control apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a prescribed field strength at any place within an area while reducing interference by considering and regulating an antenna installation height, a target area radius, a vertical beam width, setting of a tilting angle thereof and a mutual relation thereof. <P>SOLUTION: The present invention relates to a base station comprising an antenna for transmitting/receiving radio waves within an area under control, wherein a vertical beam width of the antenna is set on the basis of an estimated angle calculated from the antenna installation height and the area radius. Furthermore, in the present invention, a tilting angle formed from a horizontal direction at an apex of the antenna and a maximum direction of a radiation field of radio waves can also be set on the basis of the estimated angle. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a base station, an antenna control method, and an antenna control apparatus in mobile communication that transmits and receives radio waves in an area such as a cellular system.

  As an area configuration method for a mobile communication system, a method called a cellular method is generally used. This cellular system is a system that covers the service area widely by dividing the service area into a plurality of small areas called cells (or sectors) and arranging a base station device and an antenna for each cell. .

  In this conventional cellular system, it is necessary to obtain a predetermined electric field strength at any location in the area, and the radio wave from a certain base station is wider than the area assumed to be under the jurisdiction of the base station. When reaching an area, interference occurs with radio waves from base stations that control other areas, but there is a limit to the line capacity processed by one base station, and radio waves transmitted from the base station Therefore, it is necessary to transmit radio waves appropriately within the designed jurisdiction area.

  By the way, various places such as urban areas and suburbs can be considered as places where base stations are arranged, and cases where the area and radius of an area covered by one base station are various. Furthermore, the height at which the antenna is installed varies depending on the location where the base station is arranged. As a technique for solving the difference in height of the antenna installation height, a method of changing the tilt angle is common.

  In addition, since there are various variations of antennas used in the base station apparatus, horizontal beam width, vertical beam width, and front gain are used as indices representing the characteristics of the antenna. Here, the horizontal beam width is a value (angle) indicating how much radio waves are irradiated in the horizontal direction with respect to the front direction of the antenna, and the vertical beam width is perpendicular to the antenna. It is a value (angle) indicating how much radio waves are irradiated in the direction, and the front gain is an index (times) indicating the gain of the antenna with respect to the front direction. In general, the larger the front gain, the narrower the horizontal and / or vertical beam width.

  A technique disclosed in Japanese Patent Laid-Open No. 2000-270361 (Patent Document 1) is known as a technique for avoiding interference while maintaining a predetermined electric field strength at any location in the area.

  In this Patent Document 1, in constructing a mobile communication system having a sector cell configuration, the directivity direction of the sector antenna should be 0.5 times or more and less than 1.0 times the value obtained by dividing 360 degrees by the number of sectors. Thus, it is disclosed that the line capacity is increased by increasing the electric field strength in the sector-oriented direction and at the same time suppressing inter-sector interference and inter-sector overlap. Further, Patent Document 1 discloses that the line capacity is further expanded by directing a sector of an adjacent cell to a weak electric field region at a sector boundary.

Further, there is Non-Patent Document 1 as a technique for avoiding interference between areas while maintaining a predetermined electric field intensity by adjusting a tilt angle.
JP 2000-270361 A Fangwei Tong et al., Effects of Beam tilting on Bit-rate Selection in Mobile Multipath Channell, Trans. On Vehicular Technology Vol. 46, No. 2 May 1997, Lionel Zordan et al., Capacity Enhancement of Cellular Mobile Network Using a Dynamic Electrical Down -Tilting Antenna Systemm, VTC, 1999

  However, in the technique disclosed in Patent Document 1, the directivity in the horizontal direction is set such that the antenna directivity direction is 0.5 times or more and less than 1.0 times the value obtained by dividing 360 degrees by the number of sectors. However, since there is no mention of the directivity in the vertical direction, it is insufficient as a method for preventing interference in a base station having a height difference.

  Further, in the invention disclosed in Non-Patent Document 1, when adjusting the tilt angle, the vertical beam width and the installation height of the antenna are not taken into consideration, so that it corresponds to the height difference and the characteristics of the antenna. It is difficult to configure the area.

  In view of the above, the present invention has been made in view of the above, and considers the setting of the antenna installation height, target area radius, vertical beam width and tilt angle, and their interrelationships, and adjusts them. It is an object of the present invention to provide a base station, an antenna control method, and an antenna control apparatus that can obtain a predetermined electric field strength at any location in an area while reducing interference.

  In order to solve the above problems, the present invention is a base station having an antenna for transmitting and receiving radio waves in an area under its jurisdiction, and the vertical beam width of the antenna is calculated from the antenna installation height and the radius of the area. It is set based on a prospective angle. In the present invention, the vertical beam width is preferably 1 to 2 times the prospective angle.

  According to the present invention, in order to adjust the vertical beam width in accordance with the expected angle determined from the antenna installation height and the area radius, the position and area of the radio wave irradiation range are determined according to the location conditions and topography of each base station. Therefore, it can be set appropriately according to the radio wave environment, and the required electric field strength can be ensured while reducing interference with adjacent areas.

  The present invention is a base station equipped with an antenna for transmitting and receiving radio waves in an area under its jurisdiction, and the tilt angle formed by the horizontal direction at the apex of the antenna and the maximum direction of the radiated electric field of the radio wave is determined by the antenna installation height and the area. It is set based on the prospective angle calculated from the radius of. In the present invention, the tilt angle is preferably 1.2 to 1.8 times the prospective angle.

  According to the present invention, in order to adjust the tilt angle according to the expected angle obtained from the antenna installation height and area radius, the position and area of the radio wave irradiation range, the location conditions and topography of each base station, It can be set appropriately according to the radio wave environment.

  In the above invention, the tilt angle is preferably set so that the irradiation range of the antenna extends to an adjacent area according to the antenna gain. In this case, for example, when an antenna with a high front gain is used, the radio waves can be irradiated so as to reach the adjacent area, and the areas of the adjacent areas can be irradiated with each other. In addition, when irradiating each other area, not only the form of radiating radio waves to the adjacent area including its own area, but also irradiating only the adjacent area without irradiating its own area, between adjacent base stations This includes forms that illuminate alternately.

  Each of the above inventions can be implemented by the antenna control device even during operation of the base station. That is, the expected angle calculation unit that calculates the expected angle from the antenna installation height and the radius of the area, and based on the calculated expected angle, the vertical beam width of the antenna, the horizontal direction at the apex of the antenna, and the maximum of the radiation electric field of radio waves An antenna control apparatus having an arithmetic processing unit that calculates a tilt angle formed by a direction and a control unit that controls a vertical beam width or a tilt angle of the antenna based on a calculation result by the arithmetic processing unit is used. The control of the vertical beam width and tilt angle here includes, for example, changing the irradiation angle and direction of the radio wave electrically, replacing the antenna, and switching to another antenna. .

  According to the present invention, the expected angle is calculated by inputting the antenna installation height and area radius of each base station, and based on this, the vertical beam width and tilt angle at each base station can be controlled. In addition, even when the base station is in operation, the area configuration managed by each base station can be changed as appropriate according to changes in the environment of each area.

  In the above invention, the antenna gain detection unit for detecting the antenna gain of the antenna is further provided, and the arithmetic processing unit has a function of correcting the vertical beam width or the tilt angle according to the detection result by the antenna gain detection unit. preferable. In this case, the antenna gain can be detected based on the reception quality on the mobile station side, and the area configuration can be changed more flexibly based on this.

  By using the base station, the antenna control method, and the antenna control device of the present invention, it becomes possible to select an appropriate antenna according to the antenna installation height and the area radius, while suppressing interference as much as possible, and in a desired area. A mobile communication system capable of obtaining a predetermined electric field strength at any location and its area can be configured.

[First Embodiment]
Hereinafter, embodiments of the invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory diagram showing an area configuration of a base station provided with an antenna to which the antenna control method of the present invention is applied, in which (a) is a top view thereof and (b) is a side view thereof.

  As shown in FIG. 1 (a), the base station according to the present embodiment is installed to manage each of a plurality of areas, and each area has a configuration in which a substantially circular cell is adjacent to the base station. It has become. In the same figure, each cell shows that the radius is various. Each base station uses an antenna having horizontal directivity to divide each cell into a plurality of sectors. The cell shown in FIG. 1 shows a case where a so-called three-sector structure divided into three is formed.

  In addition, as shown in FIG. 1B, the mobile station according to the present embodiment has various antenna installation heights and height differences, and is set for each antenna according to the area radius where each antenna is installed. The prospective angle is different. In this embodiment, this prospective angle is defined as β in the figure, the radius of the area covered by a certain base station is defined as R, and the antenna installation height is defined as H. The prospective angle β is calculated from the area radius R and the antenna installation height H, and indicates a depression angle with respect to the horizontal direction at the top of the antenna. Therefore, in this embodiment, the relationship of tan β = R / H is established for the prospective angle β, the area radius R, and the antenna installation height.

  FIG. 2 shows a vertical beam pattern of the antenna in this embodiment. Here, the beam pattern is a graph depicting the directivity of the antenna. The front direction is set to 0 degrees, and the intensity of radio waves is distributed with respect to a location that is an angle away from the front direction. It indicates whether it is transmitted and received. A beam width φ is a value that characterizes the vertical directivity of the antenna, and this beam width φ is usually expressed as an angle at which the antenna gain (front gain) is −3 dB. In the antenna shown in FIG. 2, the vertical beam width is about 5 degrees.

  FIG. 3 shows the relationship between the prospective angle β and the vertical beam width φ of the antenna provided in the base station according to the present embodiment. FIG. 3 shows a case where the antenna is installed so that the vertical front direction of the antenna (the direction in which the radiated electric field of the radio wave is maximum) is the same as the prospective angle β.

  In this embodiment, the vertical beam width φ of the antenna is set based on a prospective angle β calculated from the antenna installation height H and the area radius R. In the present embodiment, the relationship between the expected angle β and the vertical beam width φ is such that the vertical beam width φ is 1 to 2 times the expected angle β.

  More specifically, since the antenna has directivity in the vertical plane and has a beam width φ as described above, the range irradiated with the main beam (the range irradiated with the main lobe indicated by the arrow in the figure) is the same. Therefore, the larger the prospective angle β is, the narrower it is. Therefore, when the prospective angle β is large (that is, when the antenna installation height is high or the area radius is narrow), a wider vertical beamwidth is used. If the antenna having the is not used, the area irradiated with the main lobe is reduced. Therefore, in this embodiment, as shown in FIG. 3A, when the prospective angle β is large, an antenna having a wider vertical beam width is used even if the front gain is small.

  On the other hand, as shown in FIG. 3B, when the prospective angle β is small, the irradiation range of the main lobe is kept relatively wide even if the vertical beam width is narrow. Accordingly, when the prospective angle β is small (that is, when the antenna height is low or the area radius is wide), an antenna having a narrow vertical beam width and a large front gain is used.

  According to the base station and the antenna control method according to the first embodiment as described above, the vertical beam width φ is set according to the prospective angle β obtained from the antenna installation height H and the area radius R. Can be appropriately set according to the location conditions, topography, and radio wave environment of each base station, and necessary electric field strength can be ensured while reducing interference with adjacent areas.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the present embodiment, in addition to the adjustment of the vertical beam width φ in the first embodiment described above, interference between adjacent areas is reduced by appropriately setting the tilt angle α. . FIG. 4 is an explanatory diagram illustrating setting of the antenna tilt angle in the base station and the communication method according to the second embodiment.

  As shown in FIG. 4A, the range irradiated with the vertical beam can be adjusted by giving a tilt angle. By giving a tilt angle α larger than the expected angle β calculated from the area radius R and the antenna installation height H, it becomes possible to bring the vertical beam irradiation range closer to the base station. Interference is reduced by avoiding the spread of radio waves from adjacent areas.

  At this time, if the tilt angle α is increased when the prospective angle β is large, the area irradiated with the beam becomes narrow. Therefore, as shown in FIG. 4B, even if the front gain is small, a wide vertical beam width is obtained. It is desirable to use an antenna with

  FIG. 4C shows the tilt angle setting when the prospective angle is small. As shown in the figure, when the prospective angle β is small, interference can be reduced by setting the tilt angle α to a small value. At this time, it is more efficient to use an antenna having a large front gain and a narrow vertical beam width.

  Furthermore, in the present embodiment, the relationship between the prospective angle β, the vertical beam width φ, and the tilt angle α is such that the vertical beam width φ is 1 to 2 times the prospective angle β, and the tilt angle α is 1.2 to the prospective angle β. 1.8 times is desirable. By setting the tilt angle in this way, the irradiation range of the vertical beam becomes the boundary of the own cell, and the vertical beam width is irradiated to a sufficient area near the base station of the own cell by using the antenna described above. It becomes possible.

  According to the base station and the antenna control method according to the second embodiment, in order to adjust the tilt angle α and the vertical beam width φ according to the expected angle β obtained from the antenna installation height H and the area radius R. The position and area of the radio wave irradiation range can be set appropriately according to the location conditions, topography, and radio wave environment of each base station, and the necessary electric field strength can be ensured while reducing interference with adjacent areas. it can. As a result, it is possible to prevent the adjacent area from being irradiated with the beam, and to reduce the occurrence of interference with the adjacent area.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. FIG. 5 is an explanatory diagram illustrating setting of the tilt angle of the antenna in the base station and the communication method according to the third embodiment.

  In the first embodiment and the second embodiment described above, it is desirable to use a thin vertical beam antenna when the prospective angle β is small. However, when the vertical beam width φ is narrow and the front gain is sufficiently large, As shown in FIG. 5, the tilt angle α is set so that adjacent cells are irradiated with each other. Specifically, the tilt angle α is set to be smaller than the prospective angle β so that the radio wave irradiation range extends to an adjacent area. In the illustrated example, the tilt angle α is set so that only the adjacent area is irradiated without irradiating the own area, but it is also possible to irradiate both the own area and the adjacent area. is there.

  As described above, according to the present embodiment, according to the antenna gain such as the front gain, by irradiating the adjacent cell with a small tilt angle, the apparent expected angle becomes smaller, so that a vertical beam is generated. The irradiated area can be made wider.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. The first to third embodiments described above can be applied not only at the time of base station and antenna design / installation but also at the time of operation of the base station. In the present embodiment, the communication method described in each of the above embodiments is realized by setting the vertical beam width and tilt angle in the base station by the base station controller.

  FIG. 6 is a block diagram showing an internal configuration of the base station control apparatus according to the fourth embodiment.

  As shown in the figure, the base station control device 4 is a device that adjusts the vertical beam width φ and the tilt angle α of each base station in cooperation with each base station 1, and includes a tilt angle control unit 41, A vertical beam width control unit 42, a front gain detection unit 43, a setting input unit 44, a prospective angle calculation unit 45, and an arithmetic processing unit 46 are provided.

  The setting input unit 44 is a terminal device that inputs an area radius R and an antenna installation height H for each base station, and includes a storage device 44a that stores input values (R and H) for each base station. Yes. The setting input unit 44 is connected to the prospective angle calculation unit 45, and inputs the value of each base station that is input or stored in the storage device 44 a to the prospective angle calculation unit 45. The expected angle calculation unit 45 is an arithmetic device that calculates the expected angle β based on the area radius R and the antenna installation height H input from the setting input unit 44. The value calculated by the prospective angle calculation unit 45 is sent to the arithmetic processing unit 46.

  The front gain detection unit 43 is a module that detects an antenna gain (front gain or the like) of an antenna provided in each base station. For example, the reception gain in each mobile station 2 is acquired via the base station 1, The antenna gain of the base station 1 is estimated. The value detected by the front gain detection unit 43 is sent to the arithmetic processing unit 46.

  The arithmetic processing unit 46 calculates an appropriate vertical beam width φ and tilt angle α based on the expected angle β calculated by the expected angle calculation unit 45, and outputs it to the tilt angle control unit 41 and the vertical beam width control unit 42. Arithmetic unit. The arithmetic processing unit 46 also has a function of correcting the tilt angle α and the vertical beam width φ based on the antenna gain detected by the front gain detection unit 43. For example, when the front gain is large, Since the probability that interference with an adjacent area will occur increases, these values are corrected so that the tilt angle α is increased or the vertical beam width φ is decreased. On the other hand, when the front gain is small, the probability that interference with an adjacent area will occur is low, so that the tilt angle α is reduced to correct the irradiation range of the radio wave to the adjacent area.

  The tilt angle control unit 41 and the vertical beam width control unit 42 are devices that control the setting of the antenna 3 of the base station 1 based on the tilt angle α and the vertical beam width φ calculated by the arithmetic processing unit 46. The control of the antenna by the tilt angle control unit 41 and the vertical beam control unit 42 includes, for example, changing the irradiation angle and direction of the radio wave electrically, exchanging the antenna, or switching to another antenna. Processing.

  The procedure for implementing the communication method described in the first to third embodiments described above by the base station control apparatus having the above configuration is as follows. FIG. 7 is a flowchart showing the procedure of the communication method according to this embodiment.

  As shown in the figure, first, the setting input unit 44 acquires the area radius R and the antenna installation height H for each base station (S101). These values (R and H) are acquired by input or reading from the storage device 44a. The value of each base station input to the setting input unit 44 or stored in the storage device 44 a is sent to the prospective angle calculation unit 45.

  In parallel with this step S101, the reception quality is detected in the base station 1 (S102), and the antenna gain (front gain, etc.) of the antenna provided in each base station is detected by the front gain detection unit 43. (S103).

That is, the reception quality at each mobile station 2 is acquired via the base station 1 and the antenna gain of the base station 1 is estimated. The estimated value is sent to the arithmetic processing unit 46.

  Next, it is determined whether or not the values (H, R, and antenna gain) acquired in step S101 or step S103 are changed (S104). When it is determined that there is no change, the above steps S101 to S103 are repeated by loop processing.

  On the other hand, when it is determined in step S104 that any one of the values is changed, the expected angle calculation unit 45 determines the expected angle based on the area radius R and the antenna installation height H input from the setting input unit 44. β is calculated (S105). The value calculated by the prospective angle calculation unit 45 is sent to the arithmetic processing unit 46.

  The arithmetic processing unit 46 calculates an appropriate vertical beam width φ and tilt angle α based on the expected angle β calculated by the expected angle calculation unit 45, and outputs it to the tilt angle control unit 41 and the vertical beam width control unit 42. (S106). At this time, if there is a change in the antenna gain detected by the front gain detector 43, the tilt angle α and the vertical beam width φ are corrected based on the antenna gain.

  Then, the tilt angle control unit 41 and the vertical beam width control unit 42 electrically control the setting of the antenna 3 of the base station 1 based on the tilt angle α and the vertical beam width φ calculated by the arithmetic processing unit 46 (S107). ). Each base station changes the tilt angle α and the vertical beam width φ based on the control of the tilt angle control unit 41 and the vertical beam width control unit 42, and continues communication (S108).

  According to this embodiment, the expected angle β is calculated by inputting the antenna installation height H and the area radius R of each base station, and based on this, the vertical beam width φ and tilt angle at each base station are calculated. α can be controlled, and even when the base station is in operation, the area configuration managed by each base station can be appropriately changed according to the change in the environment of each area.

  In the present embodiment, since the arithmetic processing unit 46 has a function of correcting the vertical beam width φ or the tilt angle α according to the antenna gain, it is more flexible based on the reception quality on the mobile station 2 side. The area configuration can be changed.

It is explanatory drawing which shows the area structure of the base station which concerns on 1st Embodiment, (a) is the top view, (b) is the side view. It is a graph which shows the vertical beam pattern of the antenna in 1st Embodiment. It is explanatory drawing which shows the relationship between the prospective angle (beta) of the antenna with which the base station which concerns on 1st Embodiment was equipped, and vertical beam width (phi). It is explanatory drawing which shows the setting of the tilt angle of an antenna in the base station and communication method which concern on 2nd Embodiment. It is explanatory drawing which shows the setting of the tilt angle of an antenna in the base station and communication method which concern on 3rd Embodiment. It is a block diagram which shows the internal structure of the base station control apparatus which concerns on 4th Embodiment. It is a flowchart figure which shows the procedure of the communication method which concerns on 4th Embodiment.

Explanation of symbols

α ... tilt angle β ... expected angle φ ... vertical beam width H ... antenna installation height R ... area radius 1 ... base station 2 ... mobile station 3 ... antenna 4 ... base station controller 41 ... tilt angle controller 42 ... vertical beam width Control unit 43 ... Front gain detection unit 44 ... Setting input unit 44a ... Storage device 45 ... Expected angle calculation unit 46 ... Calculation processing unit

Claims (10)

A base station equipped with an antenna for transmitting and receiving radio waves in the jurisdiction area,
The base station, wherein the vertical beam width of the antenna is set based on a prospective angle calculated from an installation height of the antenna and a radius of the area.   The base station according to claim 1, wherein the vertical beam width is 1 to 2 times the prospective angle. A base station equipped with an antenna for transmitting and receiving radio waves in the jurisdiction area,
The tilt angle formed by the horizontal direction at the apex of the antenna and the direction in which the radiated electric field of the radio wave is maximized is set based on a prospective angle calculated from an installation height of the antenna and a radius of the area. Base station.   The base station according to claim 3, wherein the tilt angle is 1.2 to 1.8 times the prospective angle.   The base station according to claim 3, wherein the tilt angle is set so that an irradiation range of the antenna extends to an adjacent area according to a gain index in a front direction of the antenna. A method for controlling an antenna for transmitting and receiving radio waves in a jurisdiction area,
The vertical beam width of the antenna is set based on the expected angle calculated from the installation height of the antenna and the radius of the area,
An antenna control method, wherein the radio wave is transmitted and received with a set vertical beam width. A method for controlling an antenna for transmitting and receiving radio waves in a jurisdiction area,
The tilt angle formed by the horizontal direction at the apex of the antenna provided in the base station and the maximum direction of the radiated electric field of the radio wave is set based on the expected angle calculated from the installation height of the antenna and the radius of the area. ,
An antenna control method, wherein the radio wave is transmitted and received with a set vertical beam width.   The antenna control method according to claim 7, wherein the tilt angle is set so that an irradiation range of the antenna extends to an adjacent area according to a gain index in a front direction of the antenna. An antenna control device that transmits and receives radio waves in a jurisdiction area,
A prospective angle calculation unit for calculating a prospective angle from the installation height of the antenna and the radius of the area;
An arithmetic processing unit that calculates a tilt angle formed by the vertical beam width of the antenna, the horizontal direction at the apex of the antenna, and the maximum direction of the radiated electric field of the radio wave based on the calculated expected angle;
An antenna control apparatus comprising: a control unit that controls a vertical beam width or a tilt angle of the antenna based on a calculation result by the arithmetic processing unit. An antenna gain detector for detecting an antenna gain of the antenna;
The antenna control device according to claim 9, wherein the arithmetic processing unit has a function of correcting the vertical beam width or the tilt angle in accordance with a detection result by the antenna gain detection unit.

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