JP2017085524A - Base station device, directivity control method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a base station device which configures a small cell to control antenna directivity according to traffic distribution.SOLUTION: The base station device, which transmits and receives radio signals between with one or a plurality of terminal devices, includes a control unit which acquires delay time information based on a transmission timing correction value of an uplink radio frame transmitted from each of the one or the plurality of terminal devices, according to a downlink radio frame transmitted from the base station device, and based on the delay time information, the base station device determines the antenna directivity in a vertical plane of one of one or a plurality of other base station devices connected to the base station device, to set the antenna directivity to one of the one or plurality of other base station devices.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a base station apparatus, a pointing direction control method, and a program.

  In a service area provided by a telecommunications carrier, a plurality of frequency bands may be used. In this case, it is not necessary to cover the same area in all of the plurality of frequency bands, and the area is constructed in a spot manner in order to increase the communication capacity in an area where traffic is tight.

  As a technique for constructing an area in a spot manner, a technique is known in which a base station apparatus changes its tilt angle to bring its own coverage closer to a target coverage (see, for example, Patent Document 1).

International Publication No. 2011/114372

3GPP (3rd Generation Partnership Project), TS36.331, “Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol specification”, V12.1.0 (2014-03) 3GPP (3rd Generation Partnership Project), TS36.211, “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation”, V12.1.0 (2014-03) 3GPP (3rd Generation Partnership Project), TS36.213, “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures”, V12.3.0 (2014-09)

  In the above-described prior art, the mobile station measures the position of the mobile station, and reports the position information of the measurement result to the base station. Therefore, the power source resource and the communication resource for reporting the position information are obtained. Is consumed. In particular, when the traffic distribution from the user varies depending on the time and time zone, if an area is constructed in spots according to the traffic distribution, the consumption of power resources increases. Furthermore, it is assumed that a small cell is deployed in the next-generation mobile communication system, and it is also assumed that the small cell controls the area in a spot manner according to the traffic distribution.

  The present invention has been made in consideration of such circumstances, and a base station apparatus capable of controlling the antenna directivity direction of a base station apparatus constituting a small cell according to traffic distribution, and directivity direction control It is to provide a method and program.

(1) One aspect of the present invention is a base station device that transmits and receives a radio signal to and from one or a plurality of terminal devices, wherein the one or more terminal devices are configured according to a downlink radio frame transmitted by the base station device. Delay time information based on a transmission timing correction value for an uplink radio frame transmitted by each of a plurality of terminal devices is acquired, and one or more connected to the base station device based on the delay time information A base station apparatus comprising: a control unit that determines an antenna directivity direction in a vertical plane of another base station apparatus and sets the antenna directivity direction in one or more of the other base station apparatuses is there.
(2) According to one aspect of the present invention, in the base station device according to (1), the control unit uses a random access channel transmitted when the one or more terminal devices first access the base station device. On the other hand, the base station apparatus acquires the delay time information based on a correction value of the transmission timing transmitted from the base station apparatus to each of the one or a plurality of terminal apparatuses.
(3) One aspect of the present invention is the base station apparatus according to (1) or (2), wherein the control unit is within the coverage of the base station apparatus based on the correction value of the transmission timing. A base station apparatus that calculates a round trip delay time distribution for each of one or a plurality of terminal apparatuses and obtains the delay time information based on the round trip delay time distribution.

(4) One aspect of the present invention is a base station apparatus that forms a small cell, which is different from the base station apparatus that forms the small cell and is transmitted by another base station apparatus that forms a macro cell. Delay time information based on a transmission timing correction value for an uplink radio frame transmitted by each of one or a plurality of terminal devices in accordance with a radio frame of the base station device is acquired from the other base station device, and the delay time is acquired. A control unit configured to determine an antenna directivity direction in a vertical plane of the antenna device of the base station device forming the small cell based on the information, and to set the antenna directivity direction in the base station device forming the small cell; Base station apparatus.
(5) One aspect of the present invention is the base station apparatus according to (4) described above, wherein the transmission timing correction value is first set to the other base station apparatus in which the one or more terminal apparatuses form the macro cell. Another base station apparatus that forms the macro cell transmits to each of the one or a plurality of terminal apparatuses with respect to a random access channel that is transmitted when accessing the mobile station.

(6) One aspect of the present invention is a directivity direction control method executed by a base station apparatus that transmits and receives radio signals to or from one or a plurality of terminal apparatuses, the downlink direction transmitted by the base station apparatus In response to a radio frame, delay time information based on a transmission timing correction value for an uplink radio frame transmitted by each of the one or a plurality of terminal devices is acquired, and based on the delay time information, the base station An antenna directivity direction in any one of one or a plurality of other base station devices connected to the station device is determined, and the antenna directivity direction is set in any of the one or a plurality of other base station devices. The directivity direction control method.

(7) One aspect of the present invention is a directivity direction control method executed by a base station apparatus that forms a small cell, which is different from the base station apparatus that forms the small cell and that forms a macro cell. Delay time information based on a transmission timing correction value for an uplink radio frame transmitted by each of one or a plurality of terminal devices according to a downlink radio frame transmitted by the base station device is transmitted to the other base station. Obtained from the device, based on the delay time information, determine the antenna directivity direction in the vertical plane of the antenna device of the base station device, and set the antenna directivity direction in the base station device forming the small cell, This is a pointing direction control method.

(8) According to one aspect of the present invention, a base station apparatus that transmits and receives radio signals to and from one or more terminal apparatuses is configured to transmit the one or more terminals according to a downlink radio frame transmitted by the base station apparatus. Delay time information based on a transmission timing correction value for an uplink radio frame transmitted by each terminal apparatus is acquired, and one or more other terminals connected to the base station apparatus are acquired based on the delay time information. A program for determining an antenna directivity direction in a vertical plane of any of the base station devices and setting the antenna directivity direction in any of the one or more other base station devices.

(9) According to one aspect of the present invention, a base station apparatus that forms a small cell is different from the base station apparatus and has 1 depending on a downlink radio frame transmitted by another base station apparatus that forms a macro cell. Or, delay time information based on a transmission timing correction value for an uplink radio frame transmitted by each of a plurality of terminal devices is acquired from the other base station device, and based on the delay time information, the base station A program for determining an antenna directivity direction in a vertical plane of an antenna device of a station device and causing the base station device forming the small cell to set the antenna directivity direction.

  ADVANTAGE OF THE INVENTION According to this invention, the antenna directivity direction of the base station apparatus which comprises a small cell can be controlled according to traffic distribution.

It is a figure which shows the radio | wireless communications system which concerns on this embodiment. It is a figure which shows the hardware structural example of the base station apparatus which concerns on this embodiment. It is a functional block diagram of the base station apparatus which concerns on this embodiment. It is a figure which shows the example of control of the directivity of the antenna which concerns on this embodiment. It is a figure which shows the example of a setting of beam width. It is a sequence chart which shows operation | movement of the radio | wireless communications system which concerns on this embodiment. It is a general | schematic sequence chart of the process which concerns on a RACH signal. It is a figure which shows TA. It is a sequence chart which shows operation | movement of the radio | wireless communications system which concerns on this embodiment. It is a functional block diagram of the base station apparatus which concerns on this embodiment. It is a sequence chart which shows operation | movement of the radio | wireless communications system which concerns on this embodiment.

Next, modes for carrying out the present invention will be described with reference to the drawings. Embodiment described below is only an example and embodiment to which this invention is applied is not restricted to the following embodiment.
Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments, and the repetitive description will be omitted.

<First Embodiment>
FIG. 1 is a schematic diagram of a wireless communication system according to the present embodiment. The wireless communication system includes a first base station device 100, a second base station device 200, and user terminals 50 (50a, 50b, 50c, 50d, 50e, 50f, 50g, 50h, 50i, 50j). The first base station apparatus 100 and the second base station apparatus 200 are connected by wire or wireless. Hereinafter, an arbitrary user terminal among a plurality of user terminals (50a, 50b, 50c, 50d, 50e, 50f, 50g, 50h, 50i, 50j) is represented as “user terminal 50”.

  The first base station device 100 is a macro cell, and covers the first area 150a by radiating radio waves in the first frequency band. Furthermore, the first base station apparatus 100 covers the first area 150b by radiating radio waves in a second frequency band that is a frequency band different from the first frequency band. In the present embodiment, a case where the second frequency band is higher than the first frequency band will be described as an example. The present invention can also be applied to a case where the second frequency band is a lower frequency band than the first frequency band. Hereinafter, an arbitrary first area among the first areas (150a, 150b) is referred to as “first area 150”.

  The second base station apparatus 200 is a small cell and radiates radio waves in the second frequency band. The second base station apparatus 200 covers the second area 250a or the second area 250b that is narrower than the first area 150 by controlling the directivity of the antenna. Hereinafter, an arbitrary second area of the second areas (250a, 250b) is referred to as a “second area 250”. Here, the small cell includes a pico cell, a femto cell, and the like.

  In the wireless communication system according to the present embodiment, the first area 150b covered by the first base station device 100 includes the second area 250 covered by the second base station device 200. The first base station device 100 acquires delay time information based on the correction value of the transmission timing of the uplink radio frame transmitted by each of the plurality of user terminals 50 located in the first area 150a. Then, based on the delay time information, the first base station apparatus 100 directs the antenna directivity direction of the second base station apparatus 200 to an area where the user terminals 50 are concentrated in the first area 150b. Execute control. Thereby, the wireless communication system can improve the radio wave environment in an area where user terminals are concentrated.

  In the example illustrated in FIG. 1, user terminals 50a to 50k are initially located in the first area 150a covered by the first base station apparatus 100 that is a macro cell. The first base station apparatus 100 identifies the second areas 250a and 250b where the user terminals 50 are concentrated in the first area 150a, and the second base station apparatus 200 transmits beams to the second areas 250a and 250b. Execute the control to direct The second base station apparatus 200 directs the beam directivity to the second area 250a or the second area 250b.

As a result, among the user terminals 50a-50k located in the first area 150a, the user terminals 50c, 50d, and 50e located in the second area 250a are connected to the second base station apparatus 200. . Also, among the user terminals 50a-50k located in the first area 150a, the user terminals 50g, 50i, 50j, and 50k located in the second area 250b are connected to the second base station apparatus 200. To do.
In the present embodiment, a case where a radio communication system (LTE system) called LTE (Long Term Evolution) is applied as an example of a radio communication system will be described. The LTE system is described in Non-Patent Documents 1, 2, and 3, for example.

<First base station apparatus>
FIG. 2 shows a hardware configuration of the first base station apparatus 100 according to the present embodiment. The first base station apparatus 100 includes a radio communication unit 152 that transmits and receives radio signals to and from the user terminal 50 via the antenna apparatus 170 connected to the first base station apparatus 100. An example of the antenna device 170 is a sector antenna.

Furthermore, the first base station apparatus 100 includes a communication unit 154 that communicates with other apparatuses via a backbone network, and a central processing unit (CPU) that controls the overall operation of the first base station apparatus 100. 156, a storage unit 158 for storing a computer program executed by the CPU 156 and various data, and a bus line 162 such as an address bus and a data bus for electrically connecting each component as shown in FIG. Is provided.
The storage unit 158 stores a control program 160 described later.
Since the second base station apparatus 200 according to the present embodiment has the same hardware configuration as that of the first base station apparatus 100, description thereof is omitted. However, a control program for controlling the second base station apparatus 200 is recorded in the storage unit 158.

<Functional Configuration of Embodiment>
FIG. 3 is a functional block diagram of the first base station apparatus 100 and the second base station apparatus 200 constituting the wireless communication system according to the present embodiment. The first base station apparatus 100 and the second base station apparatus 200 are connected by wire or wireless. Specifically, in the case of wireless connection, the first base station apparatus 100 and the second base station apparatus 200 are connected by a wireless backhaul line. In the present embodiment, as an example, a case will be described in which the first base station apparatus 100 and the second base station apparatus 200 are connected by wire. The present invention can also be applied to a case where the first base station apparatus 100 and the second base station apparatus 200 are connected by radio.

<Functional configuration of first base station apparatus>
The first base station apparatus 100 includes a wired communication unit 102, a wireless communication unit 104, a communication control unit 106, a delay time information acquisition unit 108, a directivity direction determination unit 110, a beam width determination unit 112, and a control signal generation unit 114. Have. Each of these units is realized by any one of the components illustrated in FIG. 2 operating according to a command from the CPU 156 according to a program such as the control program 160 stored in the storage unit 158.

<Each functional unit of the first base station apparatus>
Each part of the 1st base station apparatus 100 is demonstrated in detail. The wired communication unit 102 is realized by the communication unit 154 illustrated in FIG. 2, and transmits / receives various data (or information) to / from the second base station device 200 via a predetermined I / F. The wireless communication unit 104 is realized by the wireless communication unit 152 shown in FIG. 2, creates a wireless signal, and transmits it from the antenna device 170. The communication control unit 106 is realized by the CPU 156 illustrated in FIG. 2, and controls the wired communication unit 102 and the wireless communication unit 104.

  The delay time information acquisition unit 108 is realized by the CPU 156 illustrated in FIG. 2, and performs communication between the first base station device 100 and the user terminal 50 that performs wireless communication with the first base station device 100. Acquires information indicating the delay time. The delay time information acquisition unit 108 inputs information representing the delay time to the pointing direction determination unit 110 and the beam width determination unit 112.

  The directivity direction determination unit 110 is realized by the CPU 156 shown in FIG. 2, and is an antenna connected to the second base station apparatus 200 based on information representing the delay time input from the delay time information acquisition unit 108. The antenna directivity direction set in the apparatus 170 is determined. An example of the antenna directivity direction determined by the directivity direction determination unit 110 is a direction in a vertical plane. The directivity direction determination unit 110 inputs information indicating the directivity direction of the antenna to the control signal creation unit 114.

The beam width determination unit 112 is realized by the CPU 156 illustrated in FIG. 2, and is an antenna connected to the second base station apparatus 200 based on information representing the delay time input from the delay time information acquisition unit 108. The beam width set in the apparatus 170 is determined. The beam width determination unit 112 inputs information indicating the beam width to the control signal creation unit 114.
The control signal creation unit 114 is realized by the CPU 156 shown in FIG. 2 and includes information indicating the directivity direction input by the directivity direction determination unit 110 and information indicating the beam width input by the beam width determination unit 112. Create a control signal attached with. The control signal creation unit 114 inputs the created control signal to the wired communication unit 102. The wired communication unit 102 transmits a control signal to the second base station apparatus 200 according to control by the communication control unit 106.

<Functional configuration of second base station apparatus>
The second base station apparatus 200 includes a wired communication unit 202, a wireless communication unit 204, a communication control unit 206, a pointing direction control unit 208, and a beam width control unit 210. Each of these units is realized by any one of the components illustrated in FIG. 2 operating according to a command from the CPU 156 according to a program such as the control program 160 stored in the storage unit 158.

<Functional units of second base station apparatus>
Each part of the 2nd base station apparatus 200 is demonstrated in detail. The wired communication unit 202 is realized by the communication unit 154 illustrated in FIG. 2, and transmits / receives various data (or information) to / from the first base station apparatus 100 via a predetermined I / F. The wireless communication unit 204 is realized by the wireless communication unit 152 illustrated in FIG. 2, creates a wireless signal, and transmits it from the antenna device 170. The communication control unit 206 is realized by the CPU 156 shown in FIG. 2, and controls the wired communication unit 202 and the wireless communication unit 204.

The directivity direction control unit 208 is realized by the CPU 156 shown in FIG. 2, and is radiated by the antenna device 170 according to information indicating the directivity direction attached to the control signal input from the first base station device 100. Control by setting the direction of the radio wave.
The beam width control unit 210 is realized by the CPU 156 shown in FIG. 2, and is radiated by the antenna device 170 according to information indicating the beam width attached to the control signal input from the first base station device 100. It is controlled by setting the beam width of the radio wave.

<Directional direction>
FIG. 4 is a diagram for explaining the antenna directivity direction controlled by the second base station apparatus 200. FIG. 4 shows a tilt angle of the antenna device 170b of the second base station device 200 as an example of information indicating the antenna directivity direction. The antenna device 170a connected to the first base station device 100 and the antenna device 170b connected to the second base station device 200 are installed at a high place such as a steel tower or a building.

The first base station device 100 transmits and receives a radio signal A to and from the antenna device 170a. The first base station apparatus 100 transmits a control signal B to the second base station apparatus 200. Second base station apparatus 200 transmits control signal C to antenna apparatus 170b.
The antenna device 170b sets the tilt angle θ_tilt according to information indicating the directivity direction attached to the control signal C. The tilt angle θ_tilt of the antenna device 170b is an angle of the maximum directivity direction DirBM of the directivity characteristic on a vertical plane (plane including the z axis) perpendicular to the xy plane with reference to a horizontal plane (xy plane) parallel to the ground surface. It is. In general, the directivity direction of the main lobe BM of the vertical radiation pattern of the antenna device 170b is the maximum directivity direction DirBM. When the tilt angle θ_tilt increases (when the tilt is down), the maximum directivity direction DirBM is more directed toward the ground. For this reason, the coverage of the second base station apparatus 200 is reduced. On the other hand, when the tilt angle θ_tilt is small (up-tilt), the maximum directivity direction DirBM is directed to the sky opposite to the ground. For this reason, the coverage of the second base station apparatus 200 is expanded.

<Beam width>
FIG. 5 shows information indicating the beam width. An example of the information indicating the beam width is the angular distance between points where the radiation power (directivity) of the antenna decreases by a certain value or more from the point where the radiation power is maximum. FIG. 5 shows, as an example of the beam width, an angular distance between points at which 3 dB power is reduced from a point at which radiated power is maximum. The angular distance is also called “half-value angle”.

<Operation of wireless system>
FIG. 6 is a sequence chart showing the operation of the wireless communication system according to the present embodiment. With reference to FIG. 6, the example of operation | movement of the 1st base station apparatus 100 shown in FIG. 1 and the 2nd base station apparatus 200 is demonstrated.
In step S102, the delay time information acquisition unit 108 acquires information representing a delay time in communication between the first base station device 100 and the user terminal 50 that wirelessly communicates with the first base station device 100. . Here, a method for acquiring information representing the delay time will be described. The delay time information acquisition unit 108 acquires information representing a delay time based on an uplink (UL) timing correction value (TA (Timing Advance)). The uplink is a link in the direction from the user terminal 50 to the first base station apparatus 100.

  In the LTE system, when starting communication between a user terminal (User Equipment: UE) and a base station apparatus (eNodeB: eNB), a random access channel (Random Access CHannel: RACH) signal is used. The RACH signal is used to synchronize the UL signal between the user terminal and the base station apparatus. In response to the RACH signal received from the user terminal, the base station apparatus transmits “TA command” to the user terminal apparatus.

  FIG. 7 is a schematic sequence chart of processing related to the RACH signal. With reference to FIG. 7, the transmission procedure of the signal concerning a RACH signal is demonstrated. In step S1, a base station apparatus (eNB) alert | reports a RACH related parameter with a broadcast signal with respect to the user terminal (UE) which exists in coverage Cov. In step S2, a user terminal (UE) transmits a RACH signal using the RACH related parameters broadcast by the base station apparatus (eNB). In step S3, a base station apparatus (eNB) transmits "TA command" with respect to the user terminal (UE) which transmitted this RACH signal. In step S4, the user terminal (UE) transmits a UL data signal using the “TA command” received from the base station apparatus (eNB).

  FIG. 8 is a diagram illustrating TA. In FIG. 8, the UL timing correction value “NTA × TS [seconds]” by the TA is the downlink (DL) radio frame (DL Radio) when the user terminal transmits the UL radio frame (UL Radio Frame). Frame) is a transmission timing correction value of the UL radio frame. The downlink is a link in the direction from the first base station apparatus 100 to the user terminal 50. TS is “1/30720000” seconds.

  As the NTA, for example, “NTA = TA × 16, where TA is any integer from 0 to 1282” is used. With this UL timing correction value (TA), timing correction from 0 to 670 [microseconds] is possible. This is the synchronization of the UL signal for the user terminals that are in the range of about 0 to 100 [km] as the radius of the coverage size converted into the round-trip delay time between the first base station apparatus 100 and the user terminal 50. It is equivalent to being able to take.

The delay time information acquisition unit 108 is based on the “TA command” transmitted from the first base station apparatus 100 to the user terminal 50 for the RACH signal at the time of initial access among the RACH signals received from the user terminal 50. A round-trip delay time distribution (round-trip delay time distribution) is calculated for user terminals 50 located within the coverage of one base station apparatus 100. The delay time information acquisition unit 108 determines a representative round trip delay time based on the round trip delay time distribution. The representative round trip delay time is an example of delay time information. The following examples are given as representative round trip delay times.
(Example of representative round trip delay time) 95% tile value in round trip delay time distribution.
(Example 2 of representative round trip delay time) The longest round trip delay time in the round trip delay time distribution.
(Example 3 of representative round trip delay time) The maximum number of round trip delay times in the round trip delay time distribution.
(Example 4 of representative round trip delay time) Average value of round trip delay time in round trip delay time distribution.

  The “TA command” is also transmitted to the user terminal 50 for the RACH signal at the time of loss of synchronization. However, “TA” at the time of loss of synchronization is a difference value from the previous “TA”. When processing is performed in consideration of the difference value, “TA” at the time of loss of synchronization may be used for calculation of the round-trip delay time distribution.

  Returning to FIG. In step S <b> 104, the directivity direction determination unit 110 determines the antenna directivity direction based on the information representing the delay time acquired by the delay time information acquisition unit 108. Information representing the delay time can be used as information indicating the position of the user terminal 50 in the coverage (first area 150) of the first base station apparatus 100. From this, the direction in the vertical plane of the direction from the antenna device 170 connected to the first base station apparatus 100 to the position of the user terminal 50 based on the information indicating the delay time is obtained, and the direction in the vertical plane Is converted into a direction in the vertical plane of the direction from the antenna device 170 connected to the second base station device 200.

  In general, the distribution of the positions of user terminals within the coverage of each base station apparatus is different. For this reason, it is preferable that the directivity direction of the antenna which affects the coverage of the base station apparatus is a direction suitable for each base station apparatus. In the present embodiment, the directivity direction determination unit 110 obtains the directivity direction of the antenna of the first base station apparatus 100 based on the information indicating the delay time acquired by the delay time information acquisition unit 108, and determines the directivity direction. Conversion to a directivity direction from the antenna device 170 connected to the second base station device 200 is performed.

  The directivity direction determination unit 110 is configured to indicate the position and direction of the user terminal corresponding to the representative round trip delay time of the information representing the delay time acquired by the delay time information acquisition unit 108, and the antenna device connected to the first base station device 100 170 is determined as the directivity direction of the antenna, and the directivity direction of the antenna is converted into the directivity direction from the antenna device 170 connected to the second base station device 200. The position direction of the user terminal is a direction in a vertical plane from the antenna device 170. The correspondence relationship between the representative round-trip delay time and the terminal position direction in the antenna device 170 connected to the second base station device 200 is set in the directivity direction determination unit 110 in advance. For example, the directivity direction determination unit 110 holds a correspondence table indicating a correspondence relationship between the representative round-trip delay time and the position and direction of the user terminal in the antenna device 170 connected to the second base station device 200.

  In step S <b> 106, the beam width determination unit 112 determines the beam width based on information representing the delay time acquired by the delay time information acquisition unit 108. Information indicating the delay time can be used as information indicating the position of the user terminal 50 in the coverage of the first base station apparatus 100. Furthermore, the information indicating the delay time can be used as information indicating the distribution of the user terminals 50 within the coverage of the first base station apparatus 100. From this, the number of user terminals 50 at the position of the user terminal 50 determined based on the information indicating the delay time is determined, and the beam width is obtained based on the number of user terminals 50. In general, the distribution of the positions of user terminals within the coverage of each base station apparatus is different. For this reason, it is preferable that the beam width that affects the coverage of the base station apparatus is a width suitable for each base station apparatus. In the present embodiment, the beam width determination unit 112 determines the beam width of the beam radiated from the antenna of the first base station apparatus 100 based on the information indicating the delay time acquired by the delay time information acquisition unit 108. To do.

  Based on the number of user terminals at the position of the user terminal corresponding to the representative round trip delay time of the information representing the delay time acquired by the delay time information acquisition unit 108, the beam width determination unit 112 determines the beam radiated from the antenna. Determine the beam width. The correspondence between the number of user terminals and the beam width is set in the beam width determination unit 112 in advance. For example, the correspondence table indicating the correspondence between the number of user terminals and the beam width is stored in the beam width determination unit 112 in advance.

  In step S <b> 108, the control signal creation unit 114 creates a control signal with information indicating the directivity direction input by the directivity direction determination unit 110 and information indicating the beam width input by the beam width determination unit 112. The control signal creation unit 114 inputs the control signal to the wired communication unit 102.

  In step S <b> 110, the wired communication unit 102 transmits the control signal input by the control signal creation unit 114 to the second base station apparatus 200. Thereby, the first base station apparatus 100 can notify the antenna directivity direction of the antenna apparatus 170 connected to the second base station apparatus 200 and the beam width of the beam radiated from the antenna.

  In step S112, the wired communication unit 202 receives the control signal transmitted by the first base station apparatus 100 and inputs the control signal to the communication control unit 206. The communication control unit 206 inputs information indicating the directivity direction attached to the control signal input by the wired communication unit 202 to the directivity direction control unit 208 and inputs information indicating the beam width to the beam width control unit 210.

  In step S <b> 114, the directivity direction control unit 208 controls the directivity direction of the antenna according to the information indicating the directivity direction input from the communication control unit 206. Information representing the directivity direction is output from the wireless communication unit 152 to the antenna device 170b, and the antenna device 170b changes the directivity direction of the antenna according to the information representing the directivity direction. Thereby, the directivity direction of the antenna of the antenna device 170b is changed based on the directivity direction of the antenna determined by the directivity direction determination unit 110. The directivity direction control unit 208 may control the directivity of the antenna of the antenna device 170 by setting the tilt angle θ_tilt of the antenna device 170b.

In step S116, the beam width control unit 210 controls the beam width of the beam emitted by the antenna device 170b according to the information indicating the beam width input from the communication control unit 206. Information representing the beam width is output from the wireless communication unit 152 to the antenna device 170b, and the antenna device 170b changes the beam width emitted by the antenna in accordance with the information representing the beam width. Thereby, the beam width of the beam radiated by the antenna of the antenna device 170b is changed based on the beam width determined by the beam width determination unit 112. Note that the beam width control unit 210 may control the beam width of the beam radiated by the antenna of the antenna device 170 by setting the half width of the beam of the antenna device 170b.
It is not necessary to control both the directivity direction and beam width of the antenna of the antenna device 170b, and one of the directivity direction and beam width of the antenna may be controlled as necessary.

According to the above-described embodiment, based on the information indicating the delay time based on the “UL timing correction value (TA)” transmitted from the first base station apparatus 100 to the user terminal 50, the first base station The antenna directivity direction of the antenna apparatus 170b of the second base station apparatus 200 connected to the apparatus 100 and / or the beam width of the beam radiated by the antenna can be controlled. Further, since the user terminal does not need to acquire the location information of the user terminal and report it to the first base station apparatus 100, the power source resource for acquiring the location information and the communication resource for the report are obtained. Each can save.
In the above-described embodiment, the present invention can be applied even when a plurality of second base station apparatuses 200 are connected to the first base station apparatus 100. Accordingly, it is possible to control both or one of the directivity direction of the antenna suitable for each of the plurality of second base station apparatuses 200 and the beam width of the beam radiated by the antenna.

  In addition, the 1st base station apparatus 100 may acquire either of the above-mentioned representative round trip delay examples 1-example 4 as information showing delay time. For example, when the 95% tile value in the round-trip delay time distribution of Example 1 of the representative round-trip delay time is acquired as information representing the delay time, a specific round-trip delay time that is too large can be excluded, and the first base station apparatus 100 Many of the user terminals that are within the coverage can be covered. In addition, the above-described representative round trip delay examples 1 to 4 may be selectively used according to the radio frequency band used by the first base station apparatus 100, the location of the first base station apparatus 100, and the like. For example, for the first base station apparatus 100 located in an area where the user terminal 50 is located locally, the maximum number of round-trip delay times in the round-trip delay time distribution of Example 3 of the representative round-trip delay time is set. Use.

<Method of updating the pointing direction and beam width>
FIG. 9 shows an operation of updating the pointing direction and beam width in the wireless communication system shown in FIG.
In step S201, the 1st base station apparatus 100 judges whether the process which updates a pointing direction or a beam width is performed. Here, an example of a method for determining whether or not to execute processing for updating the pointing direction or beam width will be described.
(Method for determining whether or not to update the pointing direction or beam width (part 1))
The directivity direction determination unit 110 of the first base station apparatus 100 determines whether or not it is a predetermined timing for executing the process of updating the directivity direction. For example, when executing the process of updating the pointing direction at a constant cycle, the pointing direction determination unit 110 determines whether or not the fixed cycle has elapsed.

(Method for determining whether to update the pointing direction or beam width (part 2))
The first base station apparatus 100 determines whether or not the status of the first base station apparatus 100 matches a condition for executing processing for updating the pointing direction or beam width. For example, the directivity direction determination unit 110 of the first base station device 100 calculates a statistical value of communication quality between user terminals that are within the coverage of the first base station device 100 at a constant cycle, and the statistical value When the change amount of the statistical value is equal to or greater than a predetermined threshold value, it is determined that the update process is executed. When the change amount of the statistical value is less than the predetermined threshold value, it is determined that the update process is not executed.

  When calculating the statistical value of the communication quality of the user terminal, the user terminal that is the target of the calculation of the communication quality statistical value may be limited to the user terminal that is in the coverage boundary portion of the first base station apparatus 100 Good. Alternatively, the pointing direction determination unit 110 calculates a statistical value of the traffic load of the first base station apparatus 100 at a constant period, and updates the pointing direction when the change amount of the statistical value is equal to or greater than a predetermined threshold. It may be. An example of the traffic load is the number of user terminals connected. Alternatively, a statistical value of the resource usage amount of the first base station apparatus 100 is calculated at a constant period, and when the change amount of the statistical value is greater than or equal to a predetermined threshold value, a process of updating the pointing direction is executed, When the change amount of the value is less than the predetermined threshold value, the process of updating the directing direction may not be executed.

In step S202, if the process of updating the pointing direction or beam width is executed as a result of the determination in step S201, the process proceeds to step S203. If the process of updating the pointing direction or beam width is not executed, the process returns to step S201. .
In step S203, the delay time information acquisition unit 108 acquires information representing a delay time in communication between the first base station device 100 and the user terminal 50 that wirelessly communicates with the first base station device 100. . The above-described step S102 of FIG. 6 can be applied to this delay time information acquisition method.

In step S <b> 204, the directivity direction determination unit 110 determines the antenna directivity direction based on the information representing the delay time acquired by the delay time information acquisition unit 108. The above-described step S104 in FIG. 6 can be applied to this antenna direction determination method.
In step S <b> 205, the beam width determination unit 112 determines the beam width of the beam emitted by the antenna based on the information representing the delay time acquired by the delay time information acquisition unit 108. The above-described step S106 in FIG. 6 can be applied to the method for determining the beam width of the antenna beam.

In step S <b> 206, the control signal creation unit 114 creates a control signal with information indicating the directivity direction and information indicating the beam width, and transmits the control signal from the wired communication unit 102 to the second base station apparatus 200.
In step S207, the communication control unit 206 determines whether or not to update the antenna directivity direction and / or beam width. The communication control unit 206 compares the directivity direction indicated by the information indicating the directivity direction attached to the control signal with the already set antenna directivity direction, and determines that the update is performed if they do not match. If so, it is determined not to update. In addition, the communication control unit 206 compares the beam width indicated by the information indicating the beam width attached to the control signal with the already set beam width, and determines that they are updated if they do not match. If so, it is determined not to update.
As a result of the determination in step S207, if both or one of the antenna directivity direction and beam width is updated, the process proceeds to step S208. If both the antenna directivity direction and beam width are not updated, the process returns to step S201.

In step S208, when updating the directivity direction of the antenna, the directivity direction control unit 208 performs control to change the directivity direction of the antenna. Thereby, information indicating the directivity direction of the antenna is output from the wireless communication unit 152 to the antenna device 170. The antenna device 170 changes the directivity direction of the antenna according to information indicating the directivity direction of the antenna. Thereby, the directivity direction of the antenna of the antenna device 170 is changed. When the beam width is updated, the beam width determination unit 112 performs control to change the beam width of the antenna beam. As a result, information representing the beam width is output from the wireless communication unit 152 to the antenna device 170. The antenna device 170 changes the beam width of the antenna according to information indicating the beam width. Thereby, the beam width of the antenna device 170 is changed.
In step S209, the second base station apparatus 200 determines the end of the update process in FIG. As a result of the determination, if the process is to be ended, the updating process of FIG. 9 is ended, and if not, the process returns to step S201.

  In step S204 of the update process, the pointing direction determination unit 110 may compare information representing the delay time acquired in step S203 with the previous one. The directivity direction determination unit 110 may update the antenna directivity direction and beam width when the difference in delay time is equal to or greater than a predetermined threshold. As a result, in the first base station apparatus 100, it can be determined whether or not both or one of the antenna directivity direction and the beam width is to be updated, and therefore processing can be performed without notifying the second base station apparatus 200.

  According to the updating method of FIG. 9, it is possible to appropriately update both or one of the antenna directivity direction and beam width. For example, if a first base station device is added to meet an increase in demand for communication speed, radio wave interference may occur between the first base station devices. On the other hand, the communication quality of the coverage boundary portion is monitored, and the direction of the antenna of the antenna device 170b connected to the second base station device 200 when it is determined that radio wave interference has occurred based on the monitoring result By executing the process of updating the signal, it is possible to automatically change the coverage and eliminate the radio wave interference.

  In addition, you may control the antenna directivity direction corresponding to a large coverage within the allowable range with respect to the 2nd base station apparatus 200 as an initial value of the directivity direction of an antenna. In step S201, the first base station apparatus 100 determines execution of the update process, but another apparatus different from the first base station apparatus 100 determines execution of the update process of the first base station apparatus 100. Then, the first base station apparatus 100 may be instructed to execute the pointing direction update process. For example, a center station that manages a plurality of first base station apparatuses 100 determines execution of update processing of the first base station apparatus 100 under the control of the center station, and sends the first base station apparatus 100 to the first base station apparatus 100 Instructing the execution of the pointing direction update process may be mentioned.

<Second Embodiment>
The radio communication system shown in FIG. 1 can be applied to the radio communication system according to the present embodiment. Further, FIG. 2 can be applied to the hardware configurations of the first base station apparatus 300 and the second base station apparatus 400 according to the present embodiment. In the radio communication system according to the present embodiment, in the radio communication system according to the first embodiment, the second base station apparatus 400 is based on information indicating the delay time notified by the first base station apparatus 300. The antenna device 170 connected to the second base station device 400 controls the antenna directivity direction and / or the beam width. As a result, the second base station apparatus 400 performs the process of determining the pointing direction and the process of determining the beam width, so that the processing load on the first base station apparatus can be reduced.

<Functional Configuration of Embodiment>
The functional configuration of this embodiment will be described. FIG. 10 is a functional block diagram of the first base station apparatus 300 and the second base station apparatus 400 constituting the wireless communication system according to the present embodiment. The first base station apparatus 300 and the second base station apparatus 400 are connected by wire or wireless. Specifically, in the case of wireless connection, the first base station apparatus 300 and the second base station apparatus 400 are connected by a wireless backhaul line. In the present embodiment, as an example, a case where the first base station apparatus 300 and the second base station apparatus 400 are connected by wire will be described. The present invention can also be applied to a case where the first base station apparatus 300 and the second base station apparatus 400 are connected by radio.

<Functional configuration of first base station apparatus>
The first base station apparatus 300 includes a wired communication unit 302, a wireless communication unit 304, a communication control unit 306, and a delay time information acquisition unit 308. Each of these units is realized by any one of the components illustrated in FIG. 2 operating according to a command from the CPU 156 according to a program such as the control program 160 stored in the storage unit 158.

<Each functional unit of the first base station apparatus>
Each part of the 1st base station apparatus 300 is demonstrated in detail. The wired communication unit 302, the wireless communication unit 304, the communication control unit 306, and the delay time information acquisition unit 308 are the wired communication unit 102, the wireless communication unit 104, and the communication of the first base station device 100 according to the first embodiment. The control unit 106 and the delay time information acquisition unit 108 can be applied. However, the delay time information acquisition unit 308 transmits information representing the delay time from the wired communication unit 302 to the second base station device 400.

<Functional configuration of second base station apparatus>
The second base station apparatus 400 includes a wired communication unit 402, a wireless communication unit 404, a communication control unit 406, a pointing direction determination unit 408, a pointing direction control unit 410, a beam width determination unit 412, and a beam width control unit 414. . Each of these units is realized by any one of the components illustrated in FIG. 2 operating according to a command from the CPU 156 according to a program such as the control program 160 stored in the storage unit 158.

<Functional units of second base station apparatus>
Each part of the 2nd base station apparatus 400 is demonstrated in detail. The wired communication unit 402, the wireless communication unit 404, the communication control unit 406, the directivity direction control unit 410, and the beam width control unit 414 are connected to the wired communication unit 202 and the wireless communication unit 202 of the second base station apparatus 200 according to the first embodiment. The communication unit 204, the communication control unit 206, the directivity direction control unit 208, and the beam width control unit 210 can be applied.

  The directivity direction determination unit 408 is realized by the CPU 156 shown in FIG. 2, and is connected to the second base station apparatus 200 based on the information indicating the delay time transmitted by the first base station apparatus 300. The antenna directivity direction set in the antenna device 170 is determined. An example of the antenna directivity direction determined by the directivity direction determination unit 408 is a direction in the vertical plane. The process performed by the directivity direction determination unit 110 of the first base station apparatus 100 according to the first embodiment described above can be applied to the process of determining the antenna directivity direction. The directivity direction determination unit 408 inputs information indicating the directivity direction of the antenna to the directivity direction control unit 410.

  The beam width determination unit 412 is realized by the CPU 156 shown in FIG. 2, and is connected to the second base station apparatus 200 based on the information representing the delay time transmitted by the first base station apparatus 300. The beam width set for the antenna device 170 is determined. The process performed by the beam width determination unit 112 of the first base station apparatus 100 according to the first embodiment described above can be applied to the process of determining the beam width. The beam width determination unit 112 inputs information indicating the beam width to the beam width control unit 414.

<Operation of wireless system>
FIG. 11 is a sequence chart showing the operation of the wireless communication system according to the present embodiment. With reference to FIG. 11, the example of operation | movement of the 1st base station apparatus 300 and the 2nd base station apparatus 400 is demonstrated.
In step S302, the delay time information acquisition unit 308 acquires information representing a delay time in communication between the first base station device 300 and the user terminal 50 that performs wireless communication with the first base station device 300. . The acquisition method described above can be applied to an acquisition method of information representing the delay time.

In step S304, the delay time information acquisition unit 308 transmits information representing the delay time from the wired communication unit 302 to the second base station apparatus 400.
In step S306, the directivity direction determination unit 408 determines the directivity direction of the antenna based on the information indicating the delay time transmitted by the first base station apparatus 300. The method in step S104 of FIG. 6 can be applied to the method of determining the antenna directivity direction.
In step S308, the beam width determination unit 412 determines the beam width based on information representing the delay time transmitted by the first base station apparatus 300. The method in step S106 in FIG. 6 can be applied to the method for determining the beam width.

  In step S <b> 310, the directivity direction control unit 410 controls the directivity direction of the antenna according to the information indicating the directivity direction input from the directivity direction determination unit 408. As a result, information indicating the directivity direction is output from the wireless communication unit 152 to the antenna device 170. The antenna device 170 changes the directivity direction of the antenna according to the information indicating the directivity direction. Thereby, the directivity direction of the antenna of the antenna device 170 is changed. The directivity direction control unit 410 may control the directivity of the antenna of the antenna device 170 by setting the tilt angle θ_tilt of the antenna device 170.

  In step S312, the beam width control unit 414 controls the beam width of the beam emitted by the antenna device 170b according to the information indicating the beam width input from the beam width determination unit 412. As a result, information indicating the beam width transmitted by the first base station apparatus 100 is output from the radio communication unit 152 to the antenna apparatus 170b. The antenna device 170b changes the beam width radiated by the antenna according to the information indicating the beam width. Thereby, the beam width of the beam radiated | emitted by the antenna of the antenna apparatus 170b is changed. Note that the beam width control unit 414 may control the beam width of the beam emitted by the antenna of the antenna device 170 by setting the half width of the beam of the antenna device 170.

  In the radio communication system according to the present embodiment, the second base station apparatus 400 transmits the information indicating the delay time from the first base station apparatus 300 to the second base station apparatus 400, so that the second base station apparatus 400 sets the delay time. Based on the information to be represented, the antenna directivity direction and beam width can be controlled. Also, if a plurality of second base station apparatuses 400 are connected to the first base station apparatus 300, the distribution of user terminals 50 is distributed to each of the plurality of second base station apparatuses 400. Accordingly, information representing different delay times can be transmitted. In this case, each of the plurality of second base station apparatuses 400 can control the antenna directivity direction and beam width based on the received information representing the delay time.

  Although the present embodiment has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes design changes and the like within a scope that does not depart from the gist of the present invention. For example, the delay time information acquisition units 108 and 308 may limit “TA” used for calculating the round-trip delay time distribution under a predetermined condition. For example, the time period during which “TA” is transmitted to the terminal device may be limited. Or you may limit the area where the terminal device which transmitted "TA" exists. Those limitations may be determined according to the usage status (the usage time zone change status, the usage zone change status, etc.) regarding the coverage of the base station apparatus 1.

  In the above-described embodiment, the control of the tilt angle of the antenna device is given as an example of the control of the antenna directivity direction. You may go. Moreover, although LTE system was mentioned as an example of a radio | wireless communications system in embodiment mentioned above, it is applicable similarly to other radio | wireless communications systems other than an LTE system.

  Further, a program for realizing the functions of the base station apparatuses 100, 200, 300 and 400 described above is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system and executed. You may make it do. Here, the “computer system” may include an OS and hardware such as peripheral devices. “Computer-readable recording medium” refers to a flexible disk, a magneto-optical disk, a ROM, a writable nonvolatile memory such as a flash memory, a portable medium such as a DVD (Digital Versatile Disk), and a built-in computer system. A storage device such as a hard disk.

Further, the “computer-readable recording medium” means a volatile memory (for example, DRAM (Dynamic DRAM) in a computer system that becomes a server or a client when a program is transmitted through a network such as the Internet or a communication line such as a telephone line. Random Access Memory)), etc., which hold programs for a certain period of time.
The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line.
The program may be for realizing a part of the functions described above.
Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.

DESCRIPTION OF SYMBOLS 50 ... User terminal 100, 300 ... 1st base station apparatus 152 ... Wireless communication part 154 ... Communication part 156 ... CPU
158 ... Storage unit 160 ... Control program 162 ... Bus line 170 ... Antenna device 200, 400 ... Second base station device

Claims (9)

A base station device that transmits and receives radio signals to and from one or more terminal devices,
Obtaining delay time information based on a transmission timing correction value for an uplink radio frame transmitted by each of the one or a plurality of terminal devices according to a downlink radio frame transmitted by the base station device;
Based on the delay time information, determine an antenna pointing direction in a vertical plane of one or more other base station devices connected to the base station device,
A base station apparatus comprising: a control unit that sets the antenna directivity direction in any of the one or a plurality of other base station apparatuses.   The control unit transmits the random access channel transmitted when the one or more terminal devices first access the base station device to each of the one or more terminal devices. The base station apparatus according to claim 1, wherein the delay time information is acquired based on a correction value of the transmission timing. The control unit calculates a round trip delay time distribution for each of one or a plurality of terminal devices within the coverage of the base station device based on the correction value of the transmission timing, and based on the round trip delay time distribution Obtaining the delay time information;
The base station apparatus according to claim 1 or 2. A base station device forming a small cell,
An uplink radio frame transmitted by each of one or a plurality of terminal devices according to a downlink radio frame transmitted by another base station device forming a macro cell, unlike the base station device forming the small cell. Delay time information based on the transmission timing correction value for the other base station apparatus,
Based on the delay time information, determine the antenna directivity direction in the vertical plane of the antenna device of the base station device forming the small cell,
A base station apparatus comprising: a control unit that sets the antenna directivity direction in a base station apparatus that forms the small cell.   The correction value of the transmission timing is set so that the one or more terminal apparatuses transmit other base station apparatuses that form the macro cell to the other base station that forms the macro cell with respect to a random access channel that is transmitted. The base station apparatus according to claim 4, wherein the station apparatus transmits to each of the one or more terminal apparatuses. A direction control method executed by a base station device that transmits and receives radio signals to or from one or more terminal devices,
According to a downlink radio frame transmitted by the base station apparatus, obtain delay time information based on a transmission timing correction value for an uplink radio frame transmitted by each of the one or more terminal apparatuses,
Based on the delay time information, determine an antenna pointing direction in a vertical plane of one or more other base station devices connected to the base station device,
A directivity direction control method for setting the antenna directivity direction in any one of the one or a plurality of other base station apparatuses. A direction control method executed by a base station apparatus forming a small cell,
An uplink radio frame transmitted by each of one or a plurality of terminal devices according to a downlink radio frame transmitted by another base station device forming a macro cell, unlike the base station device forming the small cell. Delay time information based on the transmission timing correction value for the other base station apparatus,
Based on the delay time information, determine the antenna directivity direction in the vertical plane of the antenna device of the base station device,
A directivity direction control method, wherein the antenna directivity direction is set in a base station apparatus forming the small cell. To a base station device that transmits and receives radio signals to or from one or more terminal devices,
Delay time information based on a transmission timing correction value for an uplink radio frame transmitted by each of the one or a plurality of terminal devices according to a downlink radio frame transmitted by the base station device;
Based on the delay time information, the antenna pointing direction in the vertical plane of any one or more other base station devices connected to the base station device is determined,
A program for causing any one of the one or a plurality of other base station apparatuses to set the antenna directivity direction. In the base station device that forms a small cell,
Unlike the base station apparatus, the transmission timing of an uplink radio frame transmitted by each of one or a plurality of terminal apparatuses according to a downlink radio frame transmitted by another base station apparatus forming a macro cell is determined. Delay time information based on the correction value is acquired from the other base station device,
Based on the delay time information, the antenna directivity direction in the vertical plane of the antenna device of the base station device is determined,
A program for causing a base station apparatus forming the small cell to set the antenna directivity direction.

Images