JP2019110399A - Antenna device and antenna directivity control method - Google Patents

Abstract

To set an antenna directivity according to a radio environment such as a distribution of terminals by recombination of multiple antenna elements used for MIMO transmission.SOLUTION: An antenna device, including a plurality of antenna elements each having a predetermined antenna directivity, corresponding to MIMO transmission with a terminal existing in the periphery, has a configuration in which a plurality of multiple rotary joints with antenna elements disposed at a side of a cylindrical shape is stacked, each of the rotary joints is rotated independently, and one or several pieces of antenna directivity are formed as a whole.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an antenna apparatus used in a base station of a radio access system for performing MIMO transmission, and an antenna directivity control method for adjusting antenna directivity corresponding to a communication environment such as distribution of terminals around the base station.

  High-speed wireless access systems using electromagnetic waves in the 5 GHz band include those based on standards such as IEEE 802.11a, IEEE 802.11n, and IEEE 802.11 ac.

  The high-speed wireless access system based on the IEEE802.11a standard stabilizes the characteristics in a multipath fading environment by using an orthogonal frequency division multiplexing (OFDM) modulation scheme to achieve a maximum of 54 Mbit / s. Throughput is realized.

  A high-speed wireless access system based on the IEEE802.11n standard uses MIMO (Multiple Input Multiple Output) to perform space division multiplexing with the same wireless channel using multiple antennas, and 40 MHz simultaneously using two 20 MHz frequency channels. The channel bonding technology, which utilizes the frequency channel of, achieves transmission speeds of up to 600 Mbit / s.

  A high-speed wireless access system based on the IEEE802.11ac standard uses channel bonding technology that simultaneously uses four 20 MHz frequency channels and uses it as an 80 MHz frequency channel, and multiple using the same wireless channel using multi-user MIMO. A wireless communication with higher speed and higher efficiency than the IEEE802.11n standard is realized by using a space division multiple access (SDMA) transmission technique of simultaneously transmitting to the wireless station of

  Furthermore, in order to improve the transmission characteristics of a high-speed wireless access system, it is considered to switch the directivity of an antenna used in the system. Specifically, the received power at the terminals can be increased by switching the directivity of the antenna apparatus according to the communication environment such as the distribution of terminals wirelessly communicating with the base station. For example, a technique has been proposed in which an antenna device having a dipole antenna and a plurality of parasitic elements is disposed in a base station, and the directivity of the antenna device is switched by controlling the parasitic elements (Non-Patent Document 1).

J. Cheng, M. Hashiguchi, K. Iigusa, T. Ohira, "Electronically steerable parametric array antenna for omni- and sector pattern forming applications to wireless ad hoc networks," IEE Proceedings Microwaves, antennas and propagation, 150. no. 4, Aug. 2003.

  In recent years, base stations are installed at high density to provide high communication quality. In such a communication environment, depending on the terminal wirelessly communicating with the base station, there may be cases where omnidirectionality, which is an omni characteristic, is suitable, and directionalities (horizontal and vertical planes) represented by sector characteristics are suitable. . In the prior art so far, as in Non-Patent Document 1, an antenna device that switches the directivity of the horizontal plane between the omni characteristic and the sector characteristic according to the communication environment is studied by electronic control.

  However, the cost of the electronic device for performing the electronic control and the power consumption for operating the electronic device increase. Furthermore, when using MIMO transmission, it is necessary to arrange a plurality of antenna elements in a limited space, and space saving is a problem.

  An object of the present invention is to provide an antenna apparatus and an antenna directivity control method capable of setting antenna directivity according to a radio environment such as distribution of terminals for a plurality of antenna elements used for MIMO transmission.

  According to a first aspect of the present invention, there is provided an antenna apparatus including a plurality of antenna elements each having a predetermined antenna directivity, and an antenna element corresponding to a MIMO transmission to a terminal located in the periphery, the antenna element being disposed on a cylindrical side surface A plurality of joints are stacked, and each rotary joint is rotated independently to form one or more antenna directivity as a whole.

  According to a second aspect of the present invention, in the antenna directivity control method of the antenna apparatus according to the first aspect, the arrangement surface of each antenna element of the plurality of rotary joints is directed in a plurality of directions, and for each antenna element Received signal strength and the number of antennas for each terminal, and determine the terminal density for each specific area corresponding to the position and direction, and the terminal density in the order according to the number of antennas of each terminal in the specific area And controlling the number of rotary joints to set the directivity of the antenna element.

  In the antenna directivity control method of the second invention, the number of antennas of each terminal in the specific area in step 2 is determined by its maximum value or minimum value, or average value or median value.

  In the antenna directivity control method of the second invention, the directivity of the antenna element is controlled by controlling the rotary joint in accordance with the transmission capacity and transmission speed for each terminal together with the number of antennas of each terminal in the specific area in the antenna directivity control method of the second invention. Set

  The present invention can easily set the antenna directivity according to the wireless environment such as the distribution of peripheral terminals in the entire antenna apparatus by setting the directivity of the plurality of antenna elements by the rotary joint.

It is a figure which shows the structural example of the antenna apparatus of this invention. It is a flowchart which shows the process procedure example of the antenna directivity control method of this invention. It is a figure which shows the process example in the antenna directivity control method of this invention.

FIG. 1 shows a configuration example of the antenna device of the present invention.
In FIG. 1, the antenna apparatus of the present invention is configured to include, for example, a plurality of antenna elements 11 for MIMO transmission in a base station.

  The feature of the antenna device of the present invention is, as shown in FIG. 1 (1), a configuration in which a plurality of rotary joints 12 in which an antenna element 11 of, for example, a planar antenna is disposed on a cylindrical side surface are stacked. Each rotary joint 12 can be independently rotated 360 degrees in the horizontal direction, and the directivity of the antenna element 11 can be set to a predetermined angle in the horizontal direction. In addition, as shown in FIG. 1 (2), the antenna element 11 is configured to be rotatable in the vertical direction by combining, for example, a micromotor and a gear in the shaft portion, and the directivity of the antenna element 11 is predetermined in the vertical direction. It is possible to set to an angle. The directivity of each antenna element 11 is fixed, and is indicated by an arrow in the figure as perpendicular to the arrangement plane.

  In addition, although the wiring system which connects the antenna element 11 to a transmission / reception circuit is abbreviate | omitted, the structure which provides a wiring path so that the central part of each rotary joint 12 may be penetrated may be sufficient, for example.

FIG. 2 shows an example of the processing procedure of the antenna directivity control method of the present invention.
In FIG. 2, the directivity of the plurality of antenna elements of the base station is set to be directed to different directions (S1). For example, as shown in FIG. 1 (1), the directivity of the antenna elements 11 respectively disposed in the four rotary joints 12 is set to be directed in four directions different by 90 degrees in the horizontal direction. Furthermore, as shown in FIG. 1 (2), the directivity of each antenna element 11 may be combined with the angle set in the vertical direction.

  Next, signals from peripheral terminals are received by each antenna element, the terminal ID of the received signal and the number of antennas of the terminal are acquired for each antenna element, and RSSI (received signal strength) is measured (S2). The processes of steps S1 and S2 are repeated until the directivity of the plurality of antenna elements covers all directions (S3).

  Next, the terminal density in the specific area is determined from the combination of the terminal ID and the RSSI for each directivity of each antenna element (S4). That is, a specific area in which the RSSI is equal to or more than a predetermined value is assumed for each antenna element, and the number of terminals entering the specific area is defined as the terminal density.

Here, with reference to FIG. 3, the process example of step S1-S4 is demonstrated.
FIG. 3 (1) shows a state in which the four rotary joints 12 are viewed from above, and the directions of directivity of the respective antenna elements indicated by the arrows are N, E, S and W. Here, a specific area E1 in which the RSSI is equal to or greater than a predetermined value is assumed in the E direction, and the terminals 1 to 4 entering the specific area E1 are detected. Similarly, the terminals 5 and 6 are detected assuming a specific area W1 in which the RSSI is equal to or more than a predetermined value in the W direction. Similarly, the terminal 7 is detected assuming a specific area S1 in which the RSSI is equal to or more than a predetermined value in the S direction.

  FIG. 3 (2) shows a state in which the four rotary joints 12 are viewed from the top, and the directivity of each antenna element in FIG. 3 (1) is rotated 45 degrees at a time to NE, SE, SW, NW I assume. Here, terminals 1 and 2 are detected assuming a specific area NE1 in which the RSSI is equal to or greater than a predetermined value in the NE direction. Similarly, terminals 3 and 4 are detected assuming a specific area SE1 in which the RSSI is equal to or greater than a predetermined value in the SE direction. Similarly, terminals 5 to 7 are detected assuming a specific area SW1 in which the RSSI is equal to or greater than a predetermined value in the SW direction.

  If the number of rotary joints 12 is eight, the terminal density in each specific area shown in FIGS. 3 (1) and 3 (2) can be determined at one time.

  Furthermore, the direction of the directivity of each antenna element may be finely changed, and the terminal density in each specific area may be determined, assuming each specific area. In addition, although the two-dimensional distribution of terminals in the horizontal plane is used here, a three-dimensional distribution of terminals in the horizontal plane and the vertical plane may be used.

  Next, the maximum value or the minimum value or the average value or the median value of the number of antennas of each terminal in the specific area where the terminal density is maximum is determined, and the directivity of the antenna element of the base station is set according to any of them. To do (S5). Here, as shown in FIGS. 3 (1) and 3 (2), the terminal density of the specific area E1 in the E direction is maximum at 4 and the number of antennas of each terminal is 2; therefore, two antenna elements Control the rotation of the two rotary joints 12 so that the directivity of The two antenna elements directed to the E direction are determined.

  Next, the maximum value or the minimum value or the average value or the median value of the number of antennas of each terminal in the specific area where the terminal density is the next point is determined, and the directivity of the remaining antenna elements of the base station is determined according to either. Is set (S6). Here, as shown in FIGS. 3 (1) and 3 (2), the terminal density of the specific area SW1 in the SW direction is three, which is the next point, and the number of antennas of each terminal is two, so two antennas The rotary joints of the two rotary joints 12 are controlled so that the directivity of the element is directed. The two antenna elements directed to the SW direction are determined.

  In steps S5 and S6, the number of antennas of each terminal in the specific area is the maximum value or the minimum value or the average value or the median value, but there are differences in the following effects. When the maximum number of antennas is used, the MIMO transmission characteristics of the terminals in the specific area can be maximized, but the number of antennas of base stations available in other areas is reduced. When the minimum number of antennas is used, the number of antennas of base stations that can be used in other areas is increased while securing the minimum MIMO transmission characteristics of terminals in a specific area. When using the average value or the median value of the number of antennas, it is in the middle of the characteristics when using the maximum value or the minimum value.

  Furthermore, in steps S5 and S6, when determining the direction of each antenna element, adjustment may be performed based on the transmission capacity and transmission speed for each terminal.

  Next, it is determined whether there are other unset antenna elements, and while there are unset antenna elements, the process of step S6 is repeated, and it is determined that there are no unset antenna elements (S7). ). In this case, if the directivity of the four antenna elements is determined two by two in the E direction and the SW direction, there are no unset antenna elements, and the process ends. If there are five or more antenna elements and the terminal is present in other directions, the same processing will be repeated.

  In addition, when there is room in the antenna elements, more than a specified number of antenna elements corresponding to the number of antennas of the terminal may be directed to the specific area direction. For example, when the terminals are concentrated in one direction, all antenna elements may be oriented in that direction.

11 antenna element 12 rotary joint

Claims (4)

In an antenna apparatus comprising a plurality of antenna elements each having a predetermined antenna directivity and supporting MIMO transmission with terminals located in the periphery,
A plurality of rotary joints in which the antenna elements are arranged on the side of a cylinder are stacked, and each rotary joint is independently rotated to form one or a plurality of antenna directivity as a whole. . In the antenna directivity control method of an antenna device according to claim 1,
The arrangement plane of each antenna element of the plurality of rotary joints is directed in a plurality of directions, and for each of the antenna elements, the received signal strength and the number of antennas for each terminal are acquired from the received signal from the terminal. Step 1 of determining the terminal density for each specific area to be
Step 2 of controlling the number of rotary joints according to the number of antennas of each terminal in the specific area in the order of the terminal density to set directivity of the antenna element Control method. In the antenna directivity control method according to claim 2,
The antenna directivity control method, wherein the number of antennas of each terminal in the specific area in the step 2 is determined by either the maximum value or the minimum value, or the average value or the median value. In the antenna directivity control method according to claim 2,
The step 2 sets the directivity of the antenna element by controlling the rotary joint in accordance with the transmission capacity and transmission rate to each terminal as well as the number of antennas of each terminal in the specific area. Antenna directivity control method.

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