JP7570201B2 - Control device - Google Patents

Description

The present invention relates to control technology, and in particular to a control device that controls the tilt angle of a base station device antenna.

In a communication system such as LTE (Long Term Evolution), multiple base station devices are installed, and communication is performed by connecting a terminal device to one of the base station devices (see, for example, Non-Patent Document 1).

3GPP, “3GPP TS 36.101 V12.24.0”, FRANCE, 2019-12

A terminal device is generally connected to a base station device with the strongest received signal. Such a base station device may not be the closest to the terminal device or may not be able to achieve the highest transmission speed. As a result, the terminal device is not connected to the optimal base station device and communicates in an interference environment. To prevent such situations from occurring, it is necessary to optimize parameters such as the tilt angle of the antenna of the base station device. Until now, the optimization of the antenna tilt angle for LTE has been performed based on SINR (Signal-to-Interference Noise Ratio) and throughput. However, situations such as overshoot or undershoot have not been taken into consideration.

The present invention was made in consideration of these problems, and its purpose is to provide a technology that improves the accuracy of controlling the tilt angle of an antenna.

In order to solve the above problem, a control device according to one embodiment of the present invention includes a first input unit that receives first information related to a plurality of terminal devices connected to a base station device, a second input unit that receives second information related to handovers between the base station device and another base station device, a third input unit that receives third information related to the influence of interference in a band used by the base station device, a first processing unit that estimates a first distance from a base station device including a first percentage or more of terminal devices based on the first information received by the first input unit, and estimates a second distance from a base station device to which a second percentage or more of terminal devices will perform handover based on the second information received by the second input unit, and then derives a magnitude of the first distance relative to the second distance, a second processing unit that derives statistics of transmission speeds in the plurality of terminal devices based on the first information received by the first input unit, and a third processing unit that derives a percentage of the band used by the base station device where the influence of interference is greater than a predetermined value based on the third information received by the third input unit, and The base station device includes an output unit that outputs an instruction to the base station device to increase the tilt angle of the antenna when the magnitude derived in the first processing unit is greater than a first threshold value, the statistical value derived in the second processing unit is smaller than the second threshold value, and the proportion derived in the third processing unit is greater than a third threshold value ; a fourth input unit that receives fourth information regarding received signal strengths at a plurality of terminal devices, the fourth information including a first received signal strength for a signal from the base station device and a second received signal strength for a signal from another base station device; a fourth processing unit that derives a statistical value of the first received signal strength and a statistical value of the difference between the first received signal strength and a maximum second received signal strength based on the fourth information received in the fourth input unit; a fifth processing unit that derives a proportion of terminal devices that are located at a distance from the base station device that is greater than a predetermined value based on the first information received in the first input unit; and a sixth processing unit that derives a proportion of interference components included in the band used by the base station device based on the third information received in the third input unit . The output unit outputs an instruction to the base station device to reduce the tilt angle of the antenna when the statistical value of the first received signal strength derived in the fourth processing unit is smaller than the fourth threshold value, and the statistical value of the difference derived in the fourth processing unit is greater than the fifth threshold value, and the ratio derived in the fifth processing unit is greater than the sixth threshold value, and the ratio derived in the sixth processing unit is smaller than the seventh threshold value .

In addition, any combination of the above components, and any conversion between the expression of the present invention as a method, device, system, computer program, recording medium on which a computer program is recorded, etc., are also valid aspects of the present invention.

This invention improves the accuracy of controlling the antenna tilt angle.

FIG. 1 is a diagram illustrating a configuration of a communication system according to an embodiment. FIG. 2 is a diagram showing a configuration of the communication system shown in FIG. 1; FIG. 3 is a diagram showing a configuration of a control device shown in FIG. 2 . FIG. 4 is a diagram showing an overview of processing in a first processing unit in FIG. 3 . FIG. 4 is a diagram showing an outline of another process in the first processing unit in FIG. 3 . 4 is a diagram showing a data structure of a table stored in a storage unit in FIG. 3 . 4 is a flowchart showing a procedure of a process for an overshoot performed by the control device of FIG. 3 . 4 is a flowchart showing a procedure of a process for an undershoot performed by the control device of FIG. 3 .

This embodiment relates to a communication system in which a terminal device communicates with one of a plurality of base station devices. An example of a communication system is LTE, but is not limited to this. Each base station device has an antenna, and is capable of controlling the tilt angle of the antenna. The tilt angle is also called a depression angle or a dip angle, and is a downward angle based on the horizontal. Therefore, if the tilt angle is made small, the base station device transmits signals at an angle close to the horizontal, and the area in which communication with the base station device is possible is widened. On the other hand, if the tilt angle is made large, the base station device transmits signals downward, tilted from the horizontal toward the ground, and the area in which communication with the base station device is possible is narrowed.

When a base station device transmits a signal, overshoot and undershoot may occur. Overshoot is a situation in which communication with the base station device is possible in an area wider than the originally expected communication area, and undershoot is a situation in which communication with the base station device is possible only in an area narrower than the originally expected communication area. When overshoot occurs, it may cause interference with the area in which communication with an adjacent base station device is possible. When undershoot occurs, an area in which communication with neither base station device is possible may occur between the area in which communication with an adjacent base station device is possible. For this reason, it is desirable to control the tilt angle of the antenna taking overshoot or undershoot into consideration.

Figure 1 shows the configuration of a communication system 1000. The communication system 1000 includes a first base station device 10a to a seventh base station device 10g, which are collectively referred to as base station devices 10, and multiple terminal devices 14. The number of base station devices 10 included in the communication system 1000 is not formed to be "7". A first communication area 12a is formed around the first base station device 10a. The first communication area 12a is a range in which a signal from the first base station device 10a can be received, that is, a range in which communication with the first base station device 10a is possible. If the transmission power of the first base station device 10a is increased, the first communication area 12a becomes wider, and if the transmission power of the first base station device 10a is decreased, the first communication area 12a becomes narrower. When the first base station device 10a has multiple sector antennas, a communication area 12 is formed for each sector antenna, but here, for clarity of explanation, it is assumed that the first base station device 10a forms one first communication area 12a.

The second communication area 12b to the seventh communication area 12g are also formed around the second base station device 10b to the seventh base station device 10g. The first communication area 12a to the seventh communication area 12g are collectively referred to as the communication area 12. The transmission power of the first base station device 10a to the seventh base station device 10g may be different, so the size of the first communication area 12a to the seventh base station device 10g may also be different. The second communication area 12b to the seventh communication area 12g overlap with each other at the edge of the first communication area 12a. Due to such overlap of the communication areas 12, the terminal device 14 connected to the first base station device 10a moves toward the second base station device 10b, thereby realizing a handover from the first base station device 10a to the second base station device 10b.

When an overshoot occurs for the first base station device 10a, the first communication area 12a expands. As a result, even if a terminal device 14 connected to the first base station device 10a moves close to the second base station device 10b, the terminal device 14 may communicate with the first base station device 10a. As a result, communication between the terminal device 14 and the first base station device 10a interferes in the second communication area 12b. When an undershoot occurs for the first base station device 10a, the first communication area 12a narrows. As a result, for example, the first communication area 12a and the second communication area 12b do not overlap. In this situation, when the terminal device 14 connected to the first base station device 10a moves toward the second base station device 10b, the terminal device 14 cannot communicate with both the first base station device 10a and the second base station device 10b between the first communication area 12a and the second communication area 12b.

Here, when the communication system 1000 is LTE, OFDMA (Orthogonal Frequency-Division Multiple Access) is used for the downlink from the base station device 10 to the terminal device 14, so interference within the frequency is ignored. In addition, the band used by each base station device 10 is divided into 13 subbands. Each subband can be reused by each base station device 10. For example, when the same subband is used in adjacent communication areas 12 such as the first communication area 12a and the second communication area 12b, scrambling is performed on the data.

The communication system 1000 according to this embodiment identifies the base station device 10 in which an overshoot or undershoot is occurring in order to prevent the occurrence of such a situation due to an overshoot or undershoot. The communication system 1000 also controls the base station device 10 in which an overshoot or undershoot is occurring so as to change the tilt angle of the antenna.

Figure 2 shows the configuration of the communication system 1000. The communication system 1000 includes a first base station device 10a to a seventh base station device 10g, a network 100, a management system 200, and a control device 300. The management system 200 includes an OSS (Operation Support System) 210, an EMS (Element Management System) 212, an eSON (Self Organizing Network) 214, and a cell trace log 216. The management system 200 may be configured by one device or multiple devices.

Network 100 is a core network that connects multiple base station devices 10. A management system 200 and a control device 300 are also connected to network 100. OSS 210 is a system that supports the operation of communication system 1000. OSS 210 measures various items and outputs the measurement results as KPIs (Key Performance Indicators). EMS 212 is included in a network management system that serves as a human interface for communication system 1000 for operators who maintain and manage communication system 1000, and is a system that directly manages network equipment, for example, base station devices 10.

The eSON 214 collects and analyzes measurement data of network quality from the base station device 10 and terminal device 14 in operation, and the communication system 1000 autonomously controls the optimization of the operation of the base station device 10. The cell trace log 216 stores the history of the measurement results related to the base station device 10. Since the OSS 210, EMS 212, eSON 214, and cell trace log 216 may use known technologies, a description thereof will be omitted here.

The control device 300 is connected to the management system 200 via the network 100 and receives data from the management system 200. Based on the data, the control device 300 identifies the base station device 10 in which an overshoot is occurring or the base station device 10 in which an undershoot is occurring. The control device 300 also controls the tilt angle of the antenna via the network 100 for the base station device 10 in which an overshoot is occurring or the base station device 10 in which an undershoot is occurring.

Figure 3 shows the configuration of the control device 300. The control device 300 includes a first input unit 310a to a fourth input unit 310d collectively referred to as an input unit 310, a first processing unit 320a to a sixth processing unit 320f collectively referred to as a processing unit 320, a first judgment unit 330a and a second judgment unit 330b collectively referred to as a judgment unit 330, a memory unit 340, and an output unit 350. Here, the following will be described in the order of (1) processing for overshoot, and (2) processing for undershoot.

(1) Processing for Overshoot The first input unit 310a receives a KPI from the OSS 210. The KPI includes first information related to a plurality of terminal devices 14 connected to the base station device 10. The first information includes, for example, a TA (Timing Advance) for each of the plurality of terminal devices 14 and a MCS (Modulation and Coding Scheme) for each of the plurality of terminal devices 14. The first input unit 310a acquires the TA and the MCS.

TA control is a function that adjusts the transmission timing of each terminal device 14 in order to align the reception timing of signals from each terminal device 14 at one base station device 10. TA is a parameter for specifying the transmission timing of the terminal device 14, and indicates, for example, any value between 0 and 13. The closer the TA is to "0", the later the transmission timing of the terminal device 14, and the closer the TA is to "13", the earlier the transmission timing of the terminal device 14. This corresponds to the closer the TA is to "0", the closer the terminal device 14 is to the base station device 10, and the closer the TA is to "13", the farther the terminal device 14 is from the base station device 10.

The MCS is a value indicating the modulation method and error rate coding rate in communication between the base station device 10 and the terminal device 14, and corresponds to the transmission speed in communication between the base station device 10 and the terminal device 14. The MCS indicates, for example, any value from 0 to 28. The closer the MCS is to "0", the lower the transmission speed, and the closer the MCS is to "28", the higher the transmission speed.

The second input unit 310b receives second information related to handovers between the base station device 10 and other base station devices 10 from the EMS 212. The second information indicates the number of handover attempts between the base station device 10 and other base station devices 10 for each of the other base station devices 10. When focusing on the first base station device 10a, this indicates the number of handover attempts between the first base station device 10a and the second base station device 10b, the number of handover attempts between the first base station device 10a and the third base station device 10c, etc.

The third input unit 310c receives third information related to the influence of interference in the band used by the base station device 10 from the eSON 214. The third information includes an MCIM (Multi-Cell Interference Mitigation) counter. The MCIM counter includes an evaluated subband count and a total green subband count. The evaluated subband count indicates the number of subbands for which the influence of interference has been evaluated among the 13 subbands. The total green subband count indicates the number of subbands for which the influence of interference is equal to or less than a predetermined value among the subbands for which the influence of interference has been evaluated. On the other hand, a frequency subband mask is applied to subbands for which the influence of interference is greater than the predetermined value. The evaluated subband count and the total green subband count are shown as integrated values over a predetermined period, for example, 15 minutes. A known technique may be used to measure these values in the eSON 214.

The first processing unit 320a holds a correspondence relationship between each value of TA and distance, and by referring to this correspondence, derives the distance from the base station device 10 to each terminal device 14 based on the TA acquired by the first input unit 310a. The first processing unit 320a also derives the total number of terminal devices 14 having each distance. Furthermore, the first processing unit 320a derives the cumulative value of the terminal devices 14 while increasing the distance.

Figure 4 shows an overview of the processing in the first processing unit 320a. The horizontal axis indicates distance, and the distance increases from left to right. Therefore, the distance plotted on the leftmost side corresponds to TA "0", and the distance plotted on the rightmost side corresponds to TA "13". The first processing unit 320a derives a line A1 that approximates multiple cumulative values. For example, the least squares method is used to derive the line A1. Although the line A1 in Figure 4 is a straight line, it is not limited to a straight line and may be a curved line. The first processing unit 320a obtains the distance at which the line A1 exceeds the first ratio as the "first distance". The first distance indicates the distance from the base station device 10 that includes the terminal devices 14 that are equal to or greater than the first ratio. If the first ratio is "90%, " the first distance is called the 90% TA distance. Return to Figure 3.

The first processing unit 320a receives from the second input unit 310b the number of handover attempts between the base station device 10 and other base station devices 10, the number of attempts for each of the other base station devices 10. The first processing unit 320a also holds information on the distance between the base station device 10 and the other base station devices 10 for each of the other base station devices 10. Furthermore, the first processing unit 320a references the distance information to derive the number of handover attempts between the base station device 10 and the other base station devices 10 for each distance. Subsequently, the first processing unit 320a derives the cumulative value of the number of attempts while increasing the distance.

Figure 5 shows an overview of another process in the first processing unit 320a. The horizontal axis indicates the distance, and the distance increases from the left to the right. As described above, focusing on the first base station device 10a, in the case where the distance increases from the second base station device 10b to the seventh base station device 10g relative to the first base station device 10a, "L2" indicates the distance between the first base station device 10a and the second base station device 10b. Also, "L3" to "L7" indicate the distance between the first base station device 10a and the third base station device 10c, ..., the distance between the first base station device 10a and the seventh base station device 10g, respectively. The first processing unit 320a derives a line A2 that approximates multiple cumulative values. For example, the least squares method is used to derive the line A2. Although the line A2 in Figure 5 is a straight line, it is not limited to a straight line and may be a curved line. The first processing unit 320a obtains the distance at which the line A2 exceeds the second ratio as the "second distance". The second distance is the distance from the base station device 10 at which the second percentage or more of the terminal devices 14 execute handover, and is also called the "handover radius." The second percentage is, for example, "95%." Return to FIG. 3.

The first processing unit 320a derives the magnitude of the first distance relative to the second distance by subtracting the multiplication result of the second distance and the coefficient from the first distance as follows.
Magnitude of first distance relative to second distance=first distance−coefficient×second distance Equation (1)
The coefficient is, for example, 0.75. If the 90% TA distance exceeds the handover radius, the transmission distance of the signal from the base station device 10 may be long, increasing the possibility of overshooting. The magnitude of the first distance relative to the second distance indicates the required value of the coverage radius specified by the handover radius.

ここで、＃ＭＣＳ０はＭＣＳが０である端末装置１４の数を示し、＃ＭＣＳ１はＭＣＳが１である端末装置１４の数を示し、＃ＭＣＳ２８はＭＣＳが２８である端末装置１４の数を示す。このようなＭＣＳの平均値は、複数の端末装置１４における伝送速度の統計値である。統計値として平均値以外の値が導出されてもよい。 The second processing unit 320b derives an average value of the MCS based on the MCS acquired by the first input unit 310a as follows.

Here, #MCS0 indicates the number of terminal devices 14 whose MCS is 0, #MCS1 indicates the number of terminal devices 14 whose MCS is 1, and #MCS28 indicates the number of terminal devices 14 whose MCS is 28. Such an average MCS value is a statistical value of the transmission speeds in a plurality of terminal devices 14. A value other than the average value may be derived as the statistical value.

The third processing unit 320c receives the evaluated subband count and the total green subband count from the third input unit 310c. The third processing unit 320c subtracts the total green subband count from the evaluated subband count and divides the subtraction result by the evaluated subband count to derive the proportion of the portion where the influence of interference is greater than a predetermined value (hereinafter referred to as the "non-total green subband count") as follows:
Percentage of Non-Total Green Subband Count = (Evaluated Subband Count - Total Green Subband Count) / Evaluated Subband Count Equation (3)
The proportion of the non-full green sub-band count corresponds to the proportion of the band used by the base station device 10 where the effect of interference is greater than a predetermined value.

The first determination unit 330a receives the magnitude of the first distance relative to the second distance from the first processing unit 320a, receives the average value of the MCS from the second processing unit 320b, and receives the proportion of the non-all green subband count from the third processing unit 320c. The first determination unit 330a compares the magnitude of the first distance relative to the second distance with a first threshold value, compares the average value of the MCS with a second threshold value, and compares the proportion of the non-all green subband count with a third threshold value.

Figure 6 shows the data structure of the table stored in the memory unit 340. As shown in the figure, the first to third thresholds are stored, for example, the first threshold is "0", the second threshold is "10", and the third threshold is "10 (%)". Returning to Figure 3, the first determination unit 330a determines that an overshoot has occurred when the magnitude of the first distance relative to the second distance is greater than the first threshold, the average value of the MCS is smaller than the second threshold, and the proportion of non-all green subband counts is greater than the third threshold.

When the first determination unit 330a determines that an overshoot has occurred, the output unit 350 outputs a signal to the base station device 10 via the network 100, instructing the focused base station device 10, for example the first base station device 10a, to increase the antenna tilt angle. For example, the antenna tilt angle is specified in multiple stages, and a value that increases the antenna tilt angle greater than the current antenna tilt angle value is selected. The base station device 10 increases the antenna tilt angle in response to the instruction.

(2) Processing for Undershoot When undershoot occurs, the communication coverage area 12 becomes smaller, the success rate of handover decreases, the number of terminal devices 14 with larger TA increases, and interference from other adjacent base station devices 10 decreases.

The fourth input unit 310d receives KPIs from the OSS 210. The KPIs include fourth information related to received signal strengths at multiple terminal devices 14. The fourth information includes a first received signal strength for a signal from a base station device 10 to which the terminal device 14 is connected, and a second received signal strength for a signal from another base station device 10 to which the terminal device 14 is not connected. The first received signal strength and the second received signal strength are, for example, RSRP (Reference Signal Received Power). RSRP is the received power of RS per resource element (bandwidth 15 kHz). RS is a known signal that is transmitted without bias in both the frequency domain and the time domain.

The fourth processing unit 320d derives an average value as a statistical value of the first received signal strength based on the fourth information received by the fourth input unit 310d. The fourth processing unit 320d also selects the maximum value from the multiple second received signal strengths, and derives an average value as a statistical value of the difference between the first received signal strength and the maximum second received signal strength.

ここで、＃ＴＡｋは、ＴＡがｋである端末装置１４の数を示す。そのため、割合は、ＴＡが０－１３の範囲を有する端末装置１４の数に対するＴＡが３－１３の範囲を有する端末装置１４の数の割合を示し、基地局装置１０からの距離が所定値よりも長い端末装置が含まれる割合に相当する。 The fifth processing unit 320e derives the proportion of terminal devices 14 whose TA has a predetermined range, based on the TA acquired by the first input unit 310a, as follows.

Here, #TAk indicates the number of terminal devices 14 whose TA is k. Therefore, the ratio indicates the ratio of the number of terminal devices 14 whose TA is in the range of 3-13 to the number of terminal devices 14 whose TA is in the range of 0-13, and corresponds to the ratio of terminal devices whose distance from the base station device 10 is longer than a predetermined value.

The sixth processing unit 320f obtains the "evaluated subband mask counter", "green subband maximum value", and "green subband total value" from the MCIM counter received from the third input unit 310c. Known techniques may be used for the "evaluated subband mask counter", "green subband maximum value", and "green subband total value", and therefore a description thereof will be omitted here. The sixth processing unit 320f derives the "total subband" and "red subband" as follows.
Total Subbands = Estimated Subband Mask Counter x Green Subband Max Equation (5)
Red Subband = Total Subband - Green Subband Total Equation (6)

Furthermore, the sixth processing unit 320f derives the proportion of interference components contained in the band used by the base station device 10 as follows.
Proportion of interference components included=Red subband/Total subband×100 Equation (7)
That is, the total subband corresponds to the band used by the base station device 10, and the red subband corresponds to the interference component. The proportion of the non-total green subband count described above may be used as the proportion of the interference component included.

The second determination unit 330b receives the average value of the first received signal strength and the average value of the difference between the first received signal strength and the maximum second received signal strength from the fourth processing unit 320d, receives the percentage from the fifth processing unit 320e, and receives the percentage of interference components included from the sixth processing unit 320f. The second determination unit 330b compares the average value of the first received signal strength with a fourth threshold value, compares the average value of the difference between the first received signal strength and the maximum second received signal strength with a fifth threshold value, compares the percentage with a sixth threshold value, and compares the percentage of interference components included with a seventh threshold value.

As shown in FIG. 6, the fourth to seventh thresholds are stored. For example, the fourth threshold is "-105 (dBm)", the fifth threshold is "-3", the sixth threshold is "70 (%)", and the seventh threshold is "0.5 (%)". Return to FIG. 3. The second determination unit 330b determines the occurrence of an undershoot when the average value of the first received signal strength is smaller than the fourth threshold, the average value of the difference between the first received signal strength and the maximum second received signal strength is larger than the fifth threshold, the ratio is larger than the sixth threshold, and the ratio of interference components included is smaller than the seventh threshold. The second determination unit 330b may add further conditions to determine the occurrence of an undershoot. For example, "Intra Frequency HOSR < 90%", "MRO counters too early/too late > 0".

When the second determination unit 330b determines that an undershoot has occurred, the output unit 350 outputs a signal to the base station device 10 via the network 100, instructing the base station device 10 of interest, for example the first base station device 10a, to reduce the antenna tilt angle. For example, a value that reduces the antenna tilt angle from the current antenna tilt angle value is selected. The base station device 10 reduces the antenna tilt angle in response to the instruction.

In terms of hardware, this configuration can be realized by any computer's CPU (Central Processing Unit), memory, and other LSIs (Large Scale Integration), and in terms of software, it can be realized by programs loaded into memory, but here we are depicting functional blocks that are realized by the cooperation of these. Therefore, those skilled in the art will understand that these functional blocks can be realized in various ways by hardware alone, or a combination of hardware and software.

The operation of the control device 300 with the above configuration will be described. FIG. 7 is a flowchart showing the procedure of the overshoot process by the control device 300. If the magnitude of the first distance relative to the second distance is greater than 0 (Y of S10), the average value of the MCS is less than 10 (Y of S12), and the non-all green subband count is greater than 10% (Y of S14), the first judgment unit 330a and the output unit 350 increase the tilt angle of the base station device 10 (S16). If the magnitude of the first distance relative to the second distance is not greater than 0 (N of S10), or the average value of the MCS is not less than 10 (N of S12), or the non-all green subband count is not greater than 10% (N of S14), the process is terminated.

Figure 8 is a flowchart showing the procedure of undershoot processing by the control device 300. If the average value of the first received signal strength is less than -105 dBm (Y of S50), the average value of the difference is greater than -3 (Y of S52), the ratio is greater than 70% (Y of S54), and the ratio of the interference component is less than 0.5% (Y of S56), the second judgment unit 330b and the output unit 350 reduce the tilt angle of the base station device 10 (S58). If the average value of the first received signal strength is not less than -105 dBm (N of S50), or the average value of the difference is not greater than -3 (N of S52), or the ratio is not greater than 70% (N of S54), or the ratio of the interference component is not less than 0.5% (N of S56), the process is terminated.

According to this embodiment, the occurrence of an overshoot is determined based on a combination of a first distance from a base station device including a first percentage or more of terminal devices and a second distance from a base station device to which a second percentage or more of terminal devices execute handover, the average MCS of the multiple terminal devices, and the percentage of the band used by the base station device where the effect of interference is greater than a predetermined value, thereby improving the accuracy of the determination. Furthermore, when the occurrence of an overshoot is determined, a change in the tilt angle of the antenna is instructed, thereby reducing the effect of the overshoot. Furthermore, when the occurrence of an overshoot is determined, a change in the tilt angle of the antenna is instructed, thereby improving the accuracy of the control of the tilt angle of the antenna.

In addition, the distance from the base station device to each terminal device is derived based on the TA, and then the first distance including the first percentage or more of terminal devices is derived, so that the accuracy of estimating the distance of the terminal devices connected to the base station device can be improved. In addition, the second distance at which the second percentage or more of the terminal devices execute handover is derived based on the cumulative number of attempts for the distance between this base station device and other base station devices, so that the accuracy of deriving the handover radius can be improved. In addition, since the determination is based on the result of subtracting the multiplication result of the second distance and the coefficient from the first distance, it is possible to detect the possibility that the transmission distance of the signal from the base station device is getting longer. In addition, since the possibility that the transmission distance of the signal from the base station device is getting longer is detected, it is possible to determine the occurrence of an overshoot. In addition, since the first percentage is 90%, the second percentage is 95%, and the coefficient is 0.75, the accuracy of determining the occurrence of an overshoot can be improved.

In addition, since the average MCS value for multiple terminal devices is derived, communication quality can be estimated. Furthermore, since the number of subbands in which the effect of interference is equal to or less than a predetermined value is subtracted from the number of subbands included in the band, and the subtraction result is divided by the number of subbands included in the band, the proportion of the portion in which the effect of interference is greater than a predetermined value can be easily derived. Furthermore, when it is determined that an overshoot has occurred, an instruction to increase the tilt angle of the antenna is output to the base station device, thereby reducing the effect of the overshoot.

In addition, since occurrence of undershoot is determined based on a first received signal strength for a signal from a base station device, a second received signal strength for a signal from another base station device, the proportion of terminal devices whose distance from the base station device is longer than a predetermined value, and the proportion of interference components included in the band used by the base station device, the accuracy of the determination can be improved. Furthermore, when occurrence of undershoot is determined, an instruction to reduce the tilt angle of the antenna is output, so the effects of undershoot can be reduced. Furthermore, when occurrence of undershoot is determined, an instruction to reduce the tilt angle of the antenna is output, so the accuracy of control of the tilt angle of the antenna can be improved.

The present disclosure has been described above based on examples. The examples are merely illustrative, and it will be understood by those skilled in the art that various modifications are possible in the combination of each of the components or each of the processing processes, and that such modifications are also within the scope of the present disclosure.

The control device 300 in this embodiment executes processing for overshoots and processing for undershoots. However, this is not limited to the above, and for example, the control device 300 may execute only one of the processing for overshoots and the processing for undershoots. This modified example can improve the flexibility of the configuration.

10 Base station device, 12 Communication area, 100 Network, 200 Management system, 210 OSS, 212 EMS, 214 eSON, 216 Cell trace log, 300 Control device, 310 Input unit, 320 Processing unit, 330 Determination unit, 340 Storage unit, 350 Output unit, 1000 Communication system.

Claims (8)

a first input unit that receives first information regarding a plurality of terminal devices connected to the base station device;
a second input unit configured to receive second information related to a handover between the base station device and another base station device;
a third input unit configured to receive third information regarding an effect of interference in a band used by the base station device;
a first processing unit that estimates a first distance from the base station device to which a first percentage or more of the terminal devices are included based on the first information received by the first input unit, and estimates a second distance from the base station device to which a second percentage or more of the terminal devices execute handover based on the second information received by the second input unit, and then derives a magnitude of the first distance relative to the second distance;
a second processing unit that derives a statistical value of the transmission speeds of the plurality of terminal devices based on the first information received by the first input unit;
a third processing unit that derives a ratio of a portion of a band used by the base station device that is affected by interference greater than a predetermined value based on the third information received by the third input unit;
an output unit that outputs an instruction to the base station device to increase a tilt angle of an antenna when the magnitude derived in the first processing unit is greater than a first threshold value, the statistical value derived in the second processing unit is less than a second threshold value, and the ratio derived in the third processing unit is greater than a third threshold value;
a fourth input unit configured to receive fourth information related to received signal strengths in the plurality of terminal devices, the fourth information including a first received signal strength for a signal from the base station device and a second received signal strength for a signal from the other base station device;
a fourth processing unit that derives a statistical value of the first received signal strength and a statistical value of a difference between the first received signal strength and a maximum of the second received signal strength based on the fourth information received by the fourth input unit;
a fifth processing unit that derives a ratio of terminal devices that are located at a distance from the base station device that is longer than a predetermined value, based on the first information received by the first input unit;
a sixth processing unit that derives a ratio of an interference component included in a band used by the base station device based on the third information received by the third input unit,
The output unit is a control device that outputs an instruction to the base station device to reduce the tilt angle of the antenna when the statistical value of the first received signal strength derived in the fourth processing unit is smaller than a fourth threshold value, the statistical value of the difference derived in the fourth processing unit is greater than a fifth threshold value, the ratio derived in the fifth processing unit is greater than a sixth threshold value, and the ratio derived in the sixth processing unit is smaller than a seventh threshold value . the first information received by the first input unit includes a Timing Advance (TA) for each of the plurality of terminal devices;
the second information received by the second input unit includes a number of handover attempts for each of the other base station devices,
The first processing unit derives a distance from the base station device to each terminal device based on the TA, and then derives the first distance including the first percentage or more of the terminal devices based on the derived distance;
the first processing unit derives the second distance at which the terminal devices that are equal to or greater than the second ratio execute handover based on the cumulative total of the number of attempts for the distance between the present base station device and the other base station device;
The control device according to claim 1 , wherein the first processing unit derives the magnitude by subtracting a result of multiplying the second distance by a coefficient from the first distance. The control device of claim 2, wherein the first ratio is 90%, the second ratio is 95%, and the coefficient is 0.75. the first information received by the first input unit includes a Modulation and Coding Scheme (MCS) for each of the plurality of terminal devices;
The control device according to claim 1 , wherein the second processing unit derives an average value of MCS in the plurality of terminal devices as a statistical value of the transmission speeds in the plurality of terminal devices. the third information received by the third input unit includes a number of subbands in which an influence of interference is equal to or less than a predetermined value when a band used by the base station device is divided into a plurality of subbands;
The control device according to any one of claims 1 to 4, wherein the third processing unit derives the ratio by subtracting the number of subbands in which the effect of the interference is equal to or less than a predetermined value from the number of subbands included in the band, and dividing the subtraction result by the number of subbands included in the band. The control device according to claim 1 , wherein the fourth processing unit derives an average value of the first received signal strength and an average value of differences between the first received signal strength and a maximum of the second received signal strength. the first information received by the first input unit includes a Timing Advance (TA) for each of the plurality of terminal devices;
The control device according to claim 1 , wherein the fifth processing unit derives, based on the TA, a ratio of terminal devices that have the TA within a predetermined range. receiving first information regarding a plurality of terminal devices connected to the base station device;
receiving second information regarding a handover performed between the base station device and another base station device;
receiving third information regarding an effect of interference in a band used by the base station device;
a step of estimating a first distance from the base station device to which a first percentage or more of the terminal devices are included based on the first information, estimating a second distance from the base station device to which a second percentage or more of the terminal devices are performing handover based on the second information, and then deriving a magnitude of the first distance relative to the second distance;
deriving a statistical value of transmission rates in the plurality of terminal devices based on the first information;
deriving a ratio of a portion of a band used by the base station device in which an influence of interference is greater than a predetermined value based on the third information;
outputting an instruction to the base station device to increase an antenna tilt angle when the derived magnitude is greater than a first threshold value, the derived statistical value is less than a second threshold value, and the derived ratio is greater than a third threshold value;
receiving fourth information related to received signal strengths at the plurality of terminal devices, the fourth information including a first received signal strength for a signal from the base station device and a second received signal strength for a signal from the other base station device;
deriving a statistical value of the first received signal strength and a statistical value of a difference between the first received signal strength and a maximum of the second received signal strength based on the fourth information;
deriving a ratio of terminal devices whose distance from the base station device is longer than a predetermined value based on the first information;
deriving a ratio of an interference component included in a band used by the base station device based on the third information;
and a step of outputting an instruction to the base station device to reduce the tilt angle of the antenna when the derived statistical value of the first received signal strength is smaller than a fourth threshold value, the derived statistical value of the difference is greater than a fifth threshold value, the derived ratio is greater than a sixth threshold value, and the derived ratio is smaller than a seventh threshold value .

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