JP6367105B2 - Interference control apparatus, communication system, and interference control method - Google Patents

Description

  The present invention relates to an interference control device, a communication system, and an interference control method for suppressing interference by a base station to be controlled.

  With the development of wireless communication technology, communication carriers are required to appropriately construct communication areas capable of wireless communication. Many conventional macro stations (base stations) construct a communication area (macro cell) with a radius of several hundred meters to a few dozen kilometers, but a dead zone of radio waves occurs only with the macro station. For such a dead zone, a femto station is installed and a communication area (femtocell) with a radius of about a few dozen meters is constructed and dealt with.

  By the way, when a femto station is installed, communication may be hindered due to interference with the radio waves of the macro station. Therefore, ingenuity for suppressing interference with the radio waves of the macro station is required for the installation of the femto station. Yes.

  In this regard, in Non-Patent Document 1, in order to suppress interference that the femto station gives to the macro station (or other femto station), the received power of the signal transmitted by the macro station is measured, and the measured value is used as a basis. A method of determining the transmission power of the femto station, that is, a method of limiting the transmission power in accordance with the presence of another station has been proposed.

Kimura, Otonari, and Seki, “Autonomous downlink interference control for LTE femtocells in residential deployment,” PIMRC 2013, pp. 392-396, Sept. 2013.

  However, in the method proposed in Non-Patent Document 1, since the transmission power of the femto station is limited without considering the degree of interference applied, the throughput of the wireless terminal connected to the femto station is reduced. Or the wireless terminal is not connected to the femto station.

  The present invention has been made in view of such a problem, and an interference control device and a communication system that suppress interference by the base station without placing unnecessary restrictions on the transmission power of the base station to be controlled. An object of the present invention is to provide an interference control method.

  According to a first aspect of the present invention, there is provided an interference control apparatus capable of communicating with a base station to be controlled and suppressing interference by the base station by controlling the base station, other than the base station. An acquisition unit that acquires reception information of transmission radio waves of the base station in the wireless communication device from a plurality of wireless communication devices that communicate with the base station, and transmission to the base station based on the acquired reception information An interference control device comprising: a request unit that requests to reduce power.

  Further, the request unit is configured such that the received power of the transmission radio wave of the base station is interference power with respect to the SINR having the received power of the transmission radio wave of the base station or the received power of the other base station as a desired power. As the received information, the base station may be requested to lower the transmission power as the received information.

  Further, based on the reception information obtained from the wireless communication device, an estimation unit that estimates a width of an interference region in which the base station interferes with a communication region of the other base station, and the estimation unit And a determination unit that determines whether to perform control on the base station based on the estimated area of the interference area, and the request unit determines that the pre-determination unit performs control on the base station. The base station may be requested to reduce transmission power.

  Further, the estimation unit is configured to determine the interference area based on angles calculated from directions of the first wireless communication device and the second wireless communication device that are receiving interference from the base station with respect to the other base stations. The determination unit may determine that the base station is to be controlled when the angle is equal to or greater than a predetermined angle.

  Further, the estimation unit estimates the size of the interference area based on a distance between the first radio communication device and the second radio communication device receiving interference from the base station, and the determination unit When the distance is equal to or greater than a predetermined distance, it may be determined that control for the base station is performed.

  The request unit may include a reduction amount calculation unit that calculates a reduction amount of transmission power.

  In addition, the request unit transmits a SINR improvement amount in the wireless communication apparatus when the received power of the other base station is a desired power and the received power of a base station other than the other base station is an interference power. The request to the base station may be made in association with the amount of power reduction.

  In addition, the request unit may improve the SINR in the radio communication apparatus when the received power of the other base station is a desired power and the received power of a base station other than the other base station is an interference power. The request to the base station may be made in association with the number of devices to reduce the transmission power.

  In addition, the request unit may include a direction calculation unit that calculates a directivity direction that suppresses interference with the base station.

  In addition, the direction calculation unit may calculate a direction with respect to another wireless communication device starting from a wireless communication device with the strongest received power of the base station as the pointing direction.

  In addition, the direction calculation unit estimates the position of the base station from the received power distribution state of the base station obtained from each of the plurality of wireless communication devices, and with respect to another wireless communication device starting from the position The direction may be calculated as the pointing direction.

  Further, the direction calculation unit receives the received power of the base station received by the wireless communication device or the received power of the other base station received by the wireless communication device as a desired power and received by the wireless communication device. The directivity direction may be calculated based on SINR when the received power of the base station is interference power.

  Moreover, it is good also as providing the determination part which determines whether it becomes control object according to the classification of the said base station.

  According to a second aspect of the present invention, there is provided a communication system including the above-described interference control apparatus and the control target base station, wherein the control target base station requests the transmission power to be reduced from the interference control apparatus. Is received, a communication system including a control unit that controls the transmission power based on the influence of a decrease in the transmission power of the local station on the wireless communication apparatus connected to the local station is provided.

  According to a third aspect of the present invention, there is provided an interference control method for suppressing interference by a base station to be controlled from a plurality of radio communication devices communicating with other base stations other than the base station. The present invention provides an interference control method including the steps of: acquiring reception information of transmission radio waves of the base station in step S1; and requesting the base station to reduce transmission power based on the acquired reception information.

  ADVANTAGE OF THE INVENTION According to this invention, the interference by the said base station can be suppressed, without applying unnecessary restriction | limiting with respect to the transmission power of the base station to be controlled.

It is a figure which shows the outline | summary of an interference control apparatus. It is a figure which shows the whole image of the communication system containing an interference control apparatus. It is a block diagram which shows the function structure of an interference control apparatus. It is a figure which shows an example of the report acquired from a radio | wireless communication apparatus. It is a figure which shows an example of the estimation method of the width of the interference area by an estimation part. It is a figure which shows an example of the calculation method of the fall amount of the transmission power requested | required of a femto station. It is a figure which shows an example of the calculation method of the directivity direction requested | required of a femto station. It is a flowchart which shows the flow of a process of an interference control apparatus. It is a figure which shows the system configuration | structure of the communication system containing the interference control apparatus of 2nd Embodiment.

[Outline of Interference Control Device 1]
First, the outline of the interference control apparatus 1 of the present invention will be described with reference to FIG.
The interference control device 1 is provided so as to be able to communicate with a base station 5 that is a target of interference suppression control. Note that the base station 5 is a radio base station that includes a plurality of transmission antennas and is capable of directivity control, and constructs a communication area by controlling the directivity of the antennas.

  The interference control device 1 reports from a plurality of wireless communication devices 6 (UE: User Equipment) communicating with a base station other than the base station 5 about the received power of the transmission radio waves of the base station 5 in the wireless communication device 6. Based on the above, the base station 5 is requested to reduce the transmission power. For the wireless communication device 6 that communicates with a base station other than the base station 5, the transmission radio wave of the base station 5 is regarded as an interference radio wave.

  When receiving a report from each of the plurality of wireless communication devices 6, the interference control device 1 estimates a range in which the base station 5 gives interference based on the position information of the wireless communication device 6 that has transmitted the report, and estimates On the basis of the result, it is determined whether the base station 5 should take measures for interference suppression. For example, when the range in which the base station 5 is causing interference is wide, the interference control device 1 determines to take measures for interference suppression, and when the range in which the base station 5 is causing interference is narrow, It is decided not to take this action.

As a result, when it is necessary to cause the base station 5 to cope with interference suppression, the interference control device 1 determines the direction in which the base station 5 is causing interference based on the position information and report of the wireless communication device 6 and The degree of interference in the direction is estimated, and the direction in which interference is suppressed and the amount of decrease in transmission power in the direction are fed back to the base station 5.
When receiving the notification from the interference control device 1, the base station 5 suppresses interference in the direction by reducing the transmission power in the notified direction.

As described above, the interference control device 1 suppresses interference only when necessary in order to take measures for interference suppression based on the report of the wireless communication device 6 receiving interference from the base station 5 to be controlled. Therefore, interference by the base station 5 can be suppressed without placing unnecessary restrictions on the transmission power of the base station 5 to be controlled.
For example, by estimating the range in which the base station 5 gives interference based on the report of the wireless communication device 6, it is possible to prevent the countermeasure for interference suppression from occurring even when the interference range is narrow. By estimating the direction in which the interference is given based on the above, it is possible to prevent the transmission power from being lowered to the direction in which no interference occurs. As a result, the throughput of the wireless communication device connected to the base station 5 is not unnecessarily lowered, and the communication state in the communication area constructed by the base station 5 can be suitably maintained.

<First Embodiment>
Hereinafter, a first embodiment of the interference control device 1 of the present invention will be described. FIG. 2 is a diagram illustrating an overview of the communication system S including the interference control device 1 of the first embodiment. As shown in FIG. 2, the communication system S includes a macro station 1 </ b> A, a femto station 5, and a wireless communication device 6. In the first embodiment, the interference control apparatus 1 is included in the macro station 1A.

The femto station 5 is a radio base station installed at an arbitrary point such as a user's house and corresponds to the base station 5 to be controlled. The femto station 5 can control the directivity of the downlink signal by providing at least a plurality of transmission antennas, and constructs a narrow communication area with a radius of about several tens of meters.
The wireless communication device 6 is an arbitrary communication device that communicates with the macro station 1A. For example, the wireless communication device 6 may be a mobile phone, a smartphone, a PC, a tablet PC, a game machine, or the like, and constructs a sensor network in the user's home. Various sensors used in some cases may be used.

  Since the wireless communication device 6 communicates with the macro station 1A, the transmission radio wave of the femto station 5 appears as an interference radio wave. In the interference control device 1 according to the first embodiment, the femto station 5 is requested to reduce the transmission power based on a report (Measurement Report) transmitted from the wireless communication device 6 to the macro station 1A.

[Configuration of Macro Station 1A (Interference Control Device 1)]
FIG. 3 is a block diagram illustrating a functional configuration of the macro station 1A including the interference control device 1 of the present invention. As shown in FIG. 3, the macro station 1A includes the interference control device 1 and the transmission / reception unit 4A. The macro station 1A adjusts the amplitude and phase of the signal transmitted from the transmission / reception unit 4A, thereby Control the transmission pattern. Note that the communication method of the macro station 1A may be TDD (Time Division Duplex) or FDD (Frequency Division Duplex).

The transmission / reception unit 4A includes a transmission antenna and a reception antenna. In the present embodiment, the macro station 1A is preferably capable of estimating the direction of arrival for estimating the position of the wireless communication device 6, and the transmission / reception unit 4A has, for example, a plurality of receptions capable of controlling the directivity of radio waves to be received. It is configured including an antenna. In addition, the transmission / reception unit 4A may include a plurality of transmission antennas capable of controlling directivity, or may include a transmission / reception antenna.
The macro station 1A (interference control device 1) communicates with a plurality of wireless communication devices 6 via the transmission / reception unit 4A, and communicates with a plurality of femto stations 5 via the transmission / reception unit 4A or a predetermined wired line.

The interference control device 1 includes a storage unit 2 and a control unit 3.
The storage unit 2 is a memory such as a ROM and a RAM, or a storage medium such as a hard disk. The storage unit 2 stores a program for operating the control unit 3 and data generated when the control unit 3 operates. The storage unit 2 also stores reports received from the wireless communication device 6.

The control unit 3 includes an acquisition unit 31, a determination unit 32, an estimation unit 33, a determination unit 34, and a request unit 35.
The acquisition unit 31 acquires reports (reception information) from the plurality of wireless communication devices 6 that communicate with the macro station 1A via the transmission / reception unit 4A. Here, an example of the report acquired by the acquisition unit 31 is shown in FIG. As illustrated in FIG. 4, the acquisition unit 31 stores the measurement result of the received power of the radio wave of each base station in each wireless communication device 6. In the case of the example illustrated in FIG. 4, the wireless communication device 6 of “UE1” has also received radio waves from the base station of “ID_11” and the base station of “ID_12” other than the macro station 1A with which it communicates. I understand. When acquiring the radio wave reception information from the wireless communication device 6, the acquisition unit 31 stores the reception information in the storage unit 2.

  The determination unit 32 determines whether or not to be a control target based on the type of the base station. When a communication network is constructed using a plurality of macro stations, some of the communication areas of the respective macro stations may overlap. In such a case, it is not preferable to set each macro station as an object of interference suppression. Therefore, the determination unit 32 determines the base to be controlled from the plurality of base stations from which the radio communication device 6 is receiving radio waves. Station 5 (in this embodiment, femto station 5) is determined.

Here, although the determination method of the determination part 32 is arbitrary, in this embodiment, it determines whether it makes it a control object based on BSID of a base station, for example. Specifically, a BSID of “ID_101” or higher is allocated to a base station that does not require control, such as a macro station, and the base stations are classified into a plurality of groups according to the value of the BSID. Then, base stations with BSIDs “ID_1 to ID_100” are controlled, and base stations with “ID_101” or higher are not controlled.
Alternatively, the number of wireless communication apparatuses that can be accommodated by the base station (for example, 8 or 400) is associated with the BSID, and it may be determined whether or not to control based on the accommodable number of base stations. Good. Since the macro station has a large capacity and the femto station has a small capacity, the BSID base station with a small capacity can be controlled.

The estimation unit 33 estimates the size of an interference area in which the femto station 5 interferes with the macro station 1A based on the report acquired from the wireless communication device 6, and the determination unit 34 determines the estimated interference area size. Based on this, it is determined whether or not to control the femto station 5. Specifically, the determination unit 34 determines that control is performed on the femto station 5 when the estimated interference area is larger than the determination criterion, and when the estimated interference region is smaller than the determination criterion. It is determined that the femto station 5 is not controlled.
Note that the determination unit 34 determines whether or not to control the femto station 5 in consideration of not only the size of the interference area but also the number of wireless communication devices 6 receiving interference from the femto station 5. It is good as well. As an example, even when the interference area is narrow, the determination unit 34 may determine that control is performed on the femto station 5 when many wireless communication devices 6 are receiving interference.

  Here, although the estimation method of the size of the interference area by the estimation unit 33 is arbitrary, an example thereof is shown in FIG. In the present embodiment, the size of the interference area is estimated based on the angle formed by the macro station 1A and the wireless communication device 6 or the distance between the plurality of wireless communication devices 6.

[Estimation of interference area based on angle]
As shown in FIG. 5A, the estimation unit 33 calculates an angle θ formed by each direction from the directions of the plurality of wireless communication devices 6 receiving interference from the femto station 5 with respect to each macro station 1A. Then, the size of the interference area is estimated. As a result of the estimation, the determination unit 34 determines that control is performed on the femto station 5 when the angle θ is equal to or greater than the determination reference angle, and determines that control is not performed on the femto station 5 when the angle θ is less than the determination reference angle. To do.

The direction of the wireless communication device 6 may be estimated based on a downlink signal transmitted from the macro station 1A to the wireless communication device 6, and an uplink transmitted from the wireless communication device 6 to the macro station 1A. It is good also as performing based on a signal.
For example, when the macro station 1A is divided into sectors and the beam width of the sector is sufficiently narrow, the direction is estimated based on the downlink signal by estimating the direction from the sector to which the wireless communication device 6 is connected. Can do. In addition, the direction estimation based on the uplink signal can be performed using an arrival direction estimation algorithm such as the MUSIC method.
Further, for example, the macro station 1A may transmit a different value as a notification signal in each direction and receive a report of the value of the notification signal from the wireless communication device 6, thereby estimating the direction.

[Estimation of interference area based on distance]
As illustrated in FIG. 5B, the estimation unit 33 estimates the size of the interference area based on the distance L between the plurality of wireless communication devices 6 receiving interference from the femto station 5. As a result of the estimation, the determination unit 34 determines that the control for the femto station 5 is performed when the distance L is equal to or greater than the determination reference distance, and determines that the control for the femto station 5 is not performed when the distance L is less than the determination distance. .

Note that the distance between the wireless communication devices 6 is the distance A between the macro station 1A and the first wireless communication device 6, the distance B between the macro station 1A and the second wireless communication device 6, and the first If the angle θ formed by the direction of the wireless communication device 6 and the direction of the second wireless communication device 6 is known, it can be estimated using the cosine theorem.
Since the estimation method of the angle θ has been described above, the estimation method of the distance between the macro station 1A and the wireless communication device 6 will be described.

(Distance estimation based on propagation loss)
Since the macro station 1A knows its own transmission power, the propagation loss between the macro station 1A and the radio communication device 6 can be determined by referring to the report (received power of the own station) acquired from the radio communication device 6. Can be obtained. Further, since the macro station 1A also knows its own frequency, the macro station 1A and the radio communication can be obtained from the propagation loss between the macro station 1A and the radio communication device 6 by using the model expression of the free space propagation loss. The distance to the device 6 can be calculated. As the model formula for the free space propagation loss, any known model formula can be used. For example, the following square model formula can be used.
Propagation loss = 32.4 + 20log (f) + 20log (d / 1000)
Note that f is the frequency of the macro station 1A, and d is the distance between the macro station 1A and the wireless communication device 6.

(Distance estimation based on frame timing)
Further, the distance between the macro station 1A and the wireless communication device 6 may be estimated not by the propagation loss but by the delay time of the frame timing of the uplink signal from the wireless communication device 6. The time taken to receive a response from the wireless communication device 6 to the notification signal transmitted by the macro station 1A is proportional to the distance between the macro station 1A and the wireless communication device 6. Therefore, the distance between the macro station 1A and the wireless communication device 6 is determined from the difference between the frame timing of the downlink signal of the macro station 1A and the arrival time of the uplink signal of the wireless communication device 6 corresponding to the downlink signal. May be estimated.

[Filtering of Wireless Communication Device 6]
The estimation of the interference area by the estimation unit 33 as described above is performed based on reports acquired from a plurality of wireless communication apparatuses 6 that are receiving interference from the femto station 5. Here, as the radio communication device 6 receiving the interference from the femto station 5, all the radio communication devices 6 that reported that the transmission radio wave of the femto station 5 was received in the report may be targeted. A part of the wireless communication devices 6 that have reported may be targeted.

When only a part of the wireless communication devices 6 is targeted, as an example, only the wireless communication device 6 whose reception power of the transmission radio wave of the femto station 5 is higher than the threshold is targeted, and the wireless communication device whose reception power is lower than the threshold 6 may be excluded. In addition, for the wireless communication device 6 having a high signal to interference plus noise ratio (SINR), the communication quality with the macro station 1A is not deteriorated, and therefore only the wireless communication device 6 having a SINR lower than the threshold is targeted. The wireless communication device 6 whose SINR is higher than the threshold may be excluded.
As SINR, while the received power of the transmission radio wave of the macro station 1A is set as the desired power, only the reception power of the transmission radio wave of the femto station 5 may be used as the interference power, and all the bases other than the macro station 1A may be used. The reception power of the transmission radio wave of the station may be used as interference power.

In addition, when the wireless communication device 6 is indoors, the received power is attenuated due to the influence of a shielding object such as a wall. Therefore, the relationship between the propagation loss and the distance is different from that when the wireless communication device 6 is outdoors. Therefore, when estimating the distance based on the propagation loss, the wireless communication device 6 existing indoors may be excluded.
Note that when estimating the interference area based on the angle, it is only necessary to be able to estimate the direction in which the wireless communication device 6 is present, so it is not necessary to consider whether it is indoors.

  Here, whether or not the wireless communication device 6 exists indoors can be determined by an arbitrary method. For example, a notification of the number of GPS satellites supplemented by the wireless communication device 6 is sent from the wireless communication device 6. If it is less than the predetermined number of supplements, it can be determined that the wireless communication device 6 is present indoors. Moreover, it is good also as determining whether it exists indoor combining the delay time of the frame timing of the downlink signal of the radio | wireless communication apparatus 6, and a propagation loss. Specifically, it can be considered that the plurality of wireless communication devices 6 with a short delay time of the frame timing of the downlink signal exist at a substantially concentric distance from the macro station 1A. The propagation loss of each of the plurality of wireless communication apparatuses 6 is compared, and a radio wave having a propagation loss larger than a predetermined value (for example, an average value of propagation losses of the plurality of wireless communication apparatuses 6) by a predetermined value (for example, 20 dB) or more. The communication device 6 can be determined to exist indoors.

Of course, if the distance estimation is performed in consideration of the indoor penetration loss when it is present indoors, it is not necessary to set the target / non-target depending on whether it exists indoors. As a model formula of free space propagation loss when using indoor penetration loss, for example, the following model formula can be used.
Propagation loss = 32.4 + 20log (f) + 20log (d / 1000) + α
For example, α is 20 when the wireless communication apparatus 6 is indoors, and α is 0 when it is outdoors.

Returning to FIG. 3, when the determination unit 34 determines that the femto station 5 is to be controlled, the request unit 35 requests the femto station 5 to lower the transmission power based on the report acquired from the wireless communication device 6. . Note that, as a report acquired from the wireless communication device 6, the reception power of the transmission radio wave of the femto station 5 in the wireless communication device 6 may be used, and the transmission of the femto station 5 with respect to the SINR of the wireless communication device 6. It is also possible to use the influence that the received power of radio waves has as interference power.
The influence of the received power of the transmission radio wave of the femto station 5 as the interference power on the SINR of the radio communication apparatus 6 is, for example, “SINR of the radio communication apparatus 6 when there is a transmission radio wave of the femto station 5”. And “the SINR of the wireless communication apparatus 6 when there is no transmission radio wave of the femto station 5”.

  Here, the request by the request unit 35 may include one or both of a decrease amount of the transmission power and a directivity direction for decreasing the transmission power. Therefore, the request unit 35 includes a decrease amount calculation unit 351 and a direction calculation unit 352.

[Calculation of decrease in transmission power]
The decrease amount calculation unit 351 calculates a decrease amount of transmission power requested to the femto station 5. As schematically shown in FIG. 6A, in a situation where there is a wireless communication device 6 that receives interference from the femto station 5 around the femto station 5, the amount of transmission power of the femto station 5 is reduced. Therefore, the number of wireless communication devices 6 whose SINR is improved is different. At this time, since the distribution state of the wireless communication device 6 is not uniform, the transmission power of the femto station 5 is unnecessarily lowered depending on the distribution state of the wireless communication device 6.

Therefore, the decrease amount calculation unit 351 calculates the importance indicating the importance of interference suppression in association with the decrease amount requested to the femto station 5. Specifically, the reduction amount calculation unit 351 calculates the importance for each reduction amount based on the improvement amount of SINR of the wireless communication device 6 and the number of wireless communication devices 6 whose SINR is improved.
For example, as illustrated in FIG. 6B, the decrease amount calculation unit 351 calculates a value proportional to the number of radio communication apparatuses 6 whose SINR is improved as the importance. In the case of the example shown in FIG. 6B, when the reduction amount is 3 dB, the number of wireless communication apparatuses 6 that improve SINR is small and the importance is low, but when the reduction amount is 6 dB. It can be seen that the number of wireless communication devices 6 with improved SINR is large and the importance is high.

  In the example shown in FIG. 6B, the importance is calculated based on the number of radio communication apparatuses 6 whose SINR is improved by 3 dB or more. However, the actual improvement amount of SINR is different in each radio communication apparatus 6. Since they are different, the decrease amount calculation unit 351 may calculate the importance after weighting the number of the wireless communication devices 6 based on the actual improvement amount. As an example, the decrease amount calculation unit 351 calculates the importance of the latter higher when the SINR is improved by 3 dB in the five wireless communication devices 6 and when the SINR is improved by 5 dB in the five wireless communication devices 6. It is good to do.

Further, as the importance calculation method, the sum of SINR improvement amounts of the wireless communication devices 6 may be used as the importance. For example, when the transmission power of the femto station is reduced by 3 dB, if the SINRs of the four wireless communication apparatuses 6 are improved by 3 dB, 2 dB, 1 dB, and 0 dB, respectively, the importance is 6 (dB).
The wireless communication device 6 having a sufficiently high SINR may not be included in the wireless communication device 6 that calculates the sum of the improvements. For example, when SINR = 20 dB is set as the threshold, even if SINR is improved to 20 dB or more, it is treated as 0 dB improvement.

[Direction calculation]
When the femto station 5 can control the directivity of the downlink signal, it is preferable to reduce the transmission power only in the direction in which the radio communication apparatus 6 receiving interference actually exists. Therefore, the direction calculation unit 352 calculates a directivity direction in which the femto station 5 suppresses interference.

  As described above, since the macro station 1A can calculate the direction and distance of the wireless communication device 6 that has reported the report, the interference control device 1 may specify the position of the wireless communication device 6 when the report is reported. it can. The interference control device 1 maps the report (received power of the femto station 5 and the like) acquired from the wireless communication device 6 according to the specified position, thereby receiving the femto station 5 as shown in FIG. The distribution status of the wireless communication device 6 according to the power can be specified.

  The direction calculation unit 352 identifies the direction in which the femto station 5 is causing interference based on the identified distribution situation, and calculates the direction as a pointing direction for suppressing interference. Here, in order to specify the direction, it is necessary to specify the starting point, but the direction calculating unit 352 specifies the starting point by the following method.

For example, when the position of the femto station 5 is known to the interference control device 1, the direction calculation unit 352 starts from the position of the femto station 5. On the other hand, when the position of the femto station 5 is not known to the interference control device 1, the direction calculation unit 352 causes the femto station estimated from the position of the wireless communication device 6 having the strongest reception power of the femto station 5 or the specified distribution state. The position of 5 is the starting point.
Since the wireless communication device 6 with the strongest reception power of the femto station 5 is located in the vicinity of the femto station 5, the direction calculation unit 352 determines the position of the wireless communication device 6 as the position of the femto station 5 in a pseudo manner. To do. Further, since the radio wave attenuates according to the distance, the distribution of the wireless communication device 6 based on the received power of the femto station 5 is concentric with the femto station 5 as the center. Therefore, the direction calculation unit 352 calculates the central part from the distribution status of the wireless communication device 6 and estimates the estimation unit as the position of the femto station 5.

  When the starting point is specified in this way, the direction calculation unit 352 causes the femto station 5 to interfere with the direction in which the wireless communication device 6 having a received intensity of the transmission radio wave of the femto station 5 is equal to or higher than the predetermined starting point. Specify the given direction. Note that when there are a plurality of wireless communication devices 6 in which the reception intensity of the transmission radio wave of the femto station 5 is equal to or greater than a predetermined value, the direction calculation unit 352 may specify a direction with a width, A plurality of directions may be specified. In addition, the direction calculation unit 352 may select an arbitrary wireless communication device 6 from the plurality of wireless communication devices 6 and specify the direction in which the wireless communication device 6 exists.

  In the example shown in FIGS. 7A and 7B, the direction in which the femto station 5 is causing interference is specified based on the received power of the femto station 5 in the wireless communication device 6. May be specified based on the SINR in the wireless communication device 6. At this time, since the SINR in the wireless communication device 6 can be specified based on the report acquired from the wireless communication device 6, the interference control device 1 also has the SINR distribution state when the transmission power of the femto station 5 is reduced. Can be acquired. The direction calculation unit 352 can identify the direction in which the femto station 5 is causing interference as described above from the distribution state and the starting point of the direction.

  Here, when the direction is specified based on the received power of the femto station 5, the same direction is specified regardless of the amount of reduction required for the femto station 5. On the other hand, when the direction is specified based on the SINR in the wireless communication device 6, not only the received power (interference power) of the femto station 5 but also the received power (desired power) of the macro station 1A is considered. As shown in FIG. 7C, the direction differs depending on the amount of decrease required for the femto station 5.

Returning to FIG. 3, the request unit 35 notifies the femto station 5 by associating the degree of importance described above in association with the amount of decrease in transmission power calculated in this way and the directivity direction in which the transmission power is reduced. 5 is requested to reduce the transmission power.
The request by the request unit 35 is made via the transceiver unit 4A of the macro station 1A, but the macro station 1A directly makes the request by transmitting radio waves from the macro station 1A to the femto station 5. Alternatively, the request to the femto station 5 may be indirectly made via the wireless communication device 6 that can detect the signal of the femto station 5 from the macro station 1A. When the interference control device 1 and the femto station 5 are connected by a wired line, the request by the request unit 35 may be made by a wired line.

When the femto station 5 receives a request from the interference control device 1, the femto station 5 may reduce the transmission power of the local station as requested, and the wireless communication device in which the decrease in the transmission power of the local station is connected to the local station. The transmission power and the directivity direction of the local station may be controlled based on the influence on the transmission. Specifically, the femto station 5 compares the degree of SINR reduction of the wireless communication apparatus communicating with the own station with the notified importance, and, for example, sets the SINR of the wireless communication apparatus communicating with the own station to a predetermined value or more. It is also possible to control the transmission power and the directivity direction of the own station within a range that can be secured.
As an example, when using the sum of SINR improvements of each wireless communication device 6 as described above as the importance, the femto station 5 uses the SINR of the wireless communication device that communicates with itself when the transmission power is reduced. The sum is calculated as an influence degree, the notified importance degree is compared with the calculated influence degree, and the transmission power and directivity direction of the own station are controlled. For example, when the reduction amount is 3 dB, if the SINRs of the two wireless communication apparatuses communicating with the femto station 5 are each reduced by 3 dB, the influence degree can be calculated as 6 (dB). The femto station 5 can control the local station by comparing the notified importance and influence with a predetermined weight. The weight can be applied based on the SINR of the wireless communication apparatus that communicates with the own station. For example, when the SINR is low, the influence weight is increased and the transmission power is lowered too much. Prevents wireless communication devices connected to stations from going out of service.

[Processing of interference control apparatus 1]
The configuration of the interference control device 1 according to the present invention has been described above. Subsequently, a processing flow of the interference control apparatus 1 will be described with reference to FIG.
In step S1, the acquisition unit 31 of the interference control device 1 acquires a report related to the reception intensity of the radio wave received by the wireless communication device 6 from the wireless communication device 6 communicating with the macro station 1A. Subsequently, in step S2, the determination unit 32 of the interference control device 1 determines whether or not the base station that is causing interference with the wireless communication device 6 is the base station 5 to be controlled (for example, the femto station 5). Determine. Specifically, the determination unit 32 specifies the type (BSID) of the base station that is causing interference to the wireless communication device 6 from the report acquired in step S1, and the type is the base station to be controlled. The determination in step S2 is performed depending on whether the type matches.

  When the femto station 5 is causing interference to the wireless communication device 6, in step S3, the estimation unit 33 of the interference control device 1 estimates an interference region where the femto station 5 is causing interference. Specifically, the estimation unit 33 determines the angle formed by the plurality of wireless communication devices 6 receiving the interference from the femto station 5 and the macro station 1 </ b> A, or between the plurality of wireless communication devices 6 receiving the interference. Based on the distance, the interference area of the base station 5 is estimated.

  Subsequently, in step S4, the determination unit 34 of the interference control device 1 determines whether or not the estimated interference region is wide. The determination unit 34 moves the process to step S5 when the interference area is larger than the determination reference, and ends the process when the interference area is smaller than the determination reference.

  In step S <b> 5, the request unit 35 of the interference control device 1 calculates a reduction amount of transmission power required for the femto station 5 and a pointing direction for suppressing interference. Specifically, the reduction amount calculation unit 351 of the request unit 35 determines the femto station 5 based on the number of wireless communication apparatuses 6 that improve SINR when the transmission power of the femto station 5 is reduced and the improvement amount of SINR. The amount of decrease in transmission power is calculated. Further, the direction calculation unit 352 of the request unit 35 calculates a directivity direction in which the femto station 5 suppresses interference based on the distribution state of the wireless communication device 6 obtained from the report acquired from the wireless communication device 6.

Subsequently, in step S6, the request unit 35 requests the femto station 5 to reduce the transmission power in a predetermined direction based on the reduction amount and the directivity direction calculated in step S5.
When this request is received, the femto station 5 compares the degree of SINR reduction of the wireless communication apparatus communicating with the own station and the notified importance, for example, and controls the transmission power and the directivity direction of the own station.

[Effect of interference control device 1]
The first embodiment of the interference control device 1 of the present invention has been described above. According to the interference control device 1 of the present invention, the following effects can be expected.
When the interference control device 1 requests the femto station 5 to reduce the transmission power, the interference control device 1 makes the request based on reports acquired from a plurality of wireless communication devices 6 communicating with the macro station 1A. Here, since the radio wave transmitted from the femto station 5 appears as an interference radio wave for the radio communication apparatus 6 communicating with the macro station 1A, the interference control apparatus 1 considers the degree of interference that the femto station 5 actually gives. Requests to the femto station 5 can be made. As a result, it is possible to prevent the transmission power from being lowered until the degree of interference is low, and the interference by the femto station 5 is suppressed without placing unnecessary restrictions on the transmission power of the femto station 5 to be controlled. can do.

In particular, the interference control device 1 requests the femto station 5 to lower the transmission power only when the interference area in which the femto station 5 is causing interference is wide, and at the time of the request, the radio that communicates with the macro station 1A. An instruction is also given for the amount of decrease in transmission power that takes into account the improvement in SINR of the communication device 6 and the direction in which interference is suppressed.
Thereby, in the femto station 5, it is sufficient to reduce the transmission power within a range that does not interfere with the communication of the wireless communication device 6, and the interference by the femto station 5 does not place unnecessary restrictions on the transmission power of the femto station 5. Can be suppressed.

  Further, since the interference control device 1 determines whether or not to be a control target based on the type (BSID) of the base station, it is possible to prevent a request to reduce transmission power even to an unnecessary base station. .

Second Embodiment
Next, a second embodiment of the interference control device 1 of the present invention will be described with reference to FIG. In the first embodiment, the interference control device 1 is provided inside the macro station 1A. In the second embodiment, the interference control device 1 is provided on the network side (server).

  Specifically, as shown in FIG. 9, the interference control device 1 (server) is connected to each of the plurality of macro stations 1A and each of the plurality of femto stations 5 via a network N such as the Internet. The interference control device 1 collects the report of the wireless communication device 6 that communicates with the macro station 1A, the position information of the wireless communication device 6 at the time of the report, and the like from each of the macro stations 1A via the network N. Similar to the first embodiment, the femto station 5 is requested to reduce the transmission power based on the information.

  The request from the interference control device 1 (server) to the femto station 5 may be made directly via the network N, or may be made via the macro station 1A close to the femto station 5, Alternatively, it may be performed via the wireless communication device 6 connected to the macro station 1A and capable of detecting the signal of the femto station 5.

Further, when the position information of the femto station 5 is held on the server, the position information of the femto station 5 may be specified by accessing the server holding the information.
Further, not only the information collected from one macro station 1A but also the information collected from a plurality of macro stations 1A may be combined to identify the interference that the femto station 5 gives to the wireless communication device 6. Good.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above embodiment. In particular, the specific embodiments of the distribution / integration of the devices are not limited to those illustrated above, and all or a part thereof may be added in arbitrary units according to various additions or according to functional loads. It can be configured functionally or physically distributed and integrated.

  For example, in the above embodiment, the size of the interference area in which the femto station 5 is causing interference is estimated based on a report (radio wave intensity or SINR) acquired from the wireless communication device 6. In this regard, the size of the interference area may be estimated by acquiring the position information (GPS information) of the wireless communication device 6 at the time of report reporting together with the report.

DESCRIPTION OF SYMBOLS 1 ... Interference control apparatus 1A ... Macro station 2 ... Memory | storage part 3 ... Control part 31 ... Acquisition part 32 ... Determination part 33 ... Estimation part 34 ... Determination part 35 ... Request unit 351 ... Drop amount calculation unit 352 ... Direction calculation unit 4A ... Transmission / reception unit 5 ... Femto station 6 ... Wireless communication device

Claims (14)

An interference control apparatus capable of communicating with a base station to be controlled and suppressing interference by the base station by controlling the base station,
An acquisition unit that acquires reception information indicating reception power of transmission radio waves of the base station in the wireless communication device from a plurality of wireless communication devices that communicate with other base stations other than the base station;
An interference region in which the base station interferes with a communication region of the other base station based on the reception information obtained from the plurality of wireless communication devices in which the reception power indicated by the reception information is higher than a threshold value An estimation unit for estimating the width of
A determination unit that determines to control the transmission power of the base station when the interference area estimated by the estimation unit is wider than a predetermined reference value;
When the determination unit determines to control the transmission power of the base station, a request unit that requests the base station to reduce the transmission power;
An interference control device comprising: The request unit uses, as the reception information, the influence of the reception power of the transmission radio wave of the base station on the SINR having the reception power of the other base station as the desired power, based on the reception information. Requesting the base station to reduce the transmission power,
The interference control apparatus according to claim 1. The estimation unit is configured to increase the interference area based on angles calculated from directions of the first radio communication device and the second radio communication device that are receiving interference from the base station with respect to the other base stations. Estimated
The determination unit determines to perform control on the base station when the angle is equal to or greater than a predetermined angle.
The interference control device according to claim 2 . The estimating unit estimates a width of the interference area based on a distance between the first wireless communication device and the second wireless communication device receiving interference from the base station;
The determination unit determines to perform control on the base station when the distance is equal to or greater than a predetermined distance;
The interference control device according to claim 2 or 3 . The request unit includes:
A decrease amount calculation unit for calculating a decrease amount of transmission power;
The interference control device according to any one of claims 1 to 4 , further comprising: The request unit determines the amount of improvement in SINR in the wireless communication apparatus when the received power of the other base station is a desired power and the received power of a base station other than the other base station is an interference power. Making the request to the base station in association with a reduction amount;
The interference control device according to claim 5 . The request unit is configured to improve SINR in the wireless communication apparatus when the received power of the other base station is desired power and the received power of a base station other than the other base station is interference power. Making the request to the base station in association with a decrease in transmission power,
The interference control device according to claim 5 or 6 . The request unit includes:
A direction calculation unit for calculating a directivity direction for suppressing interference with the base station;
An interference controller as claimed in any one of claims 1 to 7 comprising a. The direction calculation unit calculates a direction with respect to another wireless communication device starting from a wireless communication device having the strongest received power of the base station as the pointing direction.
The interference control device according to claim 8 . The direction calculation unit estimates the position of the base station from the distribution status of the received power of the base station obtained from each of the plurality of wireless communication devices, and determines the direction with respect to another wireless communication device starting from the position , Calculating as the directivity direction,
The interference control device according to claim 9 . The direction calculation unit uses the received power of the base station received by the wireless communication device or the received power of the other base station received by the wireless communication device as a desired power and the base received by the wireless communication device. Calculate the directivity direction based on SINR when the received power of the station is interference power,
The interference control apparatus according to any one of claims 8 to 10 . A determination unit that determines whether or not to be a control target according to the type of the base station,
The interference control device according to any one of claims 1 to 11 , further comprising: A base station to be controlled, and an interference control device capable of communicating with the base station,
The interference control device includes:
An acquisition unit that acquires reception information indicating reception power of transmission radio waves of the base station in the wireless communication device from a plurality of wireless communication devices that communicate with other base stations other than the base station;
An interference region in which the base station interferes with a communication region of the other base station based on the reception information obtained from the plurality of wireless communication devices in which the reception power indicated by the reception information is higher than a threshold value An estimation unit for estimating the width of
A determination unit that determines to control the transmission power of the base station when the interference area estimated by the estimation unit is wider than a predetermined reference value;
When the determination unit determines to control the transmission power of the base station, a request unit that requests the base station to reduce the transmission power;
Have
The base station to be controlled is
Upon receiving a request to reduce transmission power from the interference control device, a control unit that controls the transmission power based on the influence of a decrease in the transmission power of the local station on the wireless communication device connected to the local station,
A communication system. An interference control method for suppressing interference by a base station to be controlled,
From a plurality of wireless communication devices communicating with other base stations other than the base station, obtaining reception information indicating received power of transmission radio waves of the base station in the wireless communication device;
Based on the reception information obtained from the wireless communication apparatus in which the reception power indicated by the reception information is higher than a threshold value, a wide interference area in which the base station interferes with a communication area of the other base station. Estimating the thickness;
Determining to control the transmission power of the base station when the estimated interference area is wider than a predetermined reference value;
If it is determined to control the transmission power of the base station, requesting the base station to reduce the transmission power;
An interference control method.

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