JP6025692B2 - Area quality degradation estimation apparatus and method - Google Patents

Description

  The present invention relates to an area quality deterioration estimation apparatus and method, and in particular, deterioration of communication quality of a wireless system in an arbitrary area (for example, an estimation target area of a 100 m square area) (a large variation in communication quality in the area). The present invention relates to an area quality degradation estimation apparatus and method for estimating the frequency.

  In recent years, mobile terminals such as smartphones and tablet terminals have been rapidly spreading. Accordingly, carriers aim to expand the service area of mobile networks and improve communication quality, such as radio signal strength (RSSI (Received Signal Strength Indication), RSRP (Reference Signal Received Power), RSRQ (Reference Signal Received Quality), etc.) and throughput. The drive test has been carried out. However, since the number of points that can be measured in the drive test is limited, there are areas that cannot be detected even though the communication quality is low.

  In view of this, attention has been paid to a technique for grasping quality in a plane by utilizing information collected from user terminals. For example, a method for constructing a coverage map of a wireless system by transmitting a measurement report composed of wireless quality information and position information from a user terminal to a quality management server when communication quality falls below a predetermined threshold (For example, see Non-Patent Documents 1, 2, and 3).

Haruki Izumikawa, Shinobu Namba, Yoji Kishi, "Reliable coverage map construction method", IEICE Technical Report, 2011-5. W. A. Hapsari, A. Umesh, M. Iwamura, M. Tomola, B. Gyula, B. Sebire, "Minimization of Drive Tests Solution in 3GPP", IEEE Communications Magazine, 2012-6. Haruki Izumikawa, Ryuichi Yasunaga, Katsuhiro Kurei, Shigehiro Terachi, Yoshikazu Shirai, Nao Kobayashi, Keizo Sugiyama, "Log collection method based on QoE in MDT", IEICE Tech.

  However, it is necessary to grasp not only the area where the communication quality is deteriorated but also the area where the variation due to the date and time zone is large. This is because it is said that the communication quality experienced by the user in the past greatly affects the evaluation of the current communication quality (Non-Patent Document 4: T. Hosfeld, S. Biedermann, R. Schatz, A. Platzer, S. Egger, M. Fiedler, "The Memory Effect and Its Implications on Web QoE Modeling", ITC, 2011-9).

  As a method for grasping an area having a large variation in communication quality, a method of transmitting a measurement report from a user terminal at regular intervals is conceivable, not limited to a case where communication quality is deteriorated. However, it is conceivable that by regularly sending measurement reports from many user terminals, traffic will increase and the communication quality will deteriorate. Also, in an area where the population is relatively small, there is a possibility that a sufficient number of reports cannot be collected even by this method, and variation in communication quality cannot be grasped.

  The present invention has been made in view of the above points, and estimates whether or not there is a large variation in communication quality at the current location on the user terminal side, and compresses traffic by transmitting a measurement report only when the variation is large. It is an object of the present invention to provide an area quality degradation estimation apparatus and method capable of grasping an area where there is a large variation in communication quality.

According to one aspect, there is an area quality degradation estimation device that estimates degradation of area quality indicating that communication quality variation is large in an arbitrary area of a wireless system,
Wireless quality information acquisition means for storing the acquired wireless quality information in the storage means;
Position information acquisition means for acquiring position information of the device;
Radio quality feature quantity calculating means for calculating a radio quality feature quantity (hereinafter referred to as “radio quality feature quantity”) from the radio quality information;
Area quality deterioration estimation means for determining communication quality deterioration from variations in communication quality in the area indicated by the position information, using the wireless quality feature amount and a discriminant function for determining area quality deterioration;
When the area quality degradation estimation means determines that the communication quality is largely varied and the communication quality is degraded, the area quality degradation includes transmission means for transmitting information relating to the quality degradation to the server as a measurement report. An estimation device is provided.

  According to one aspect, by using short-time radio quality information acquired by a user terminal (area quality degradation estimation device), it is possible to estimate whether or not the communication quality at the current location is large at the user terminal. It becomes. As a result, the system side that manages the service area can accurately grasp variations in communication quality.

It is an example of system configuration in a 1st embodiment of the present invention. It is a structural example of the user terminal in the 1st Embodiment of this invention. It is a flowchart of the user terminal in the 1st Embodiment of this invention. It is an example of system configuration in a 2nd embodiment of the present invention. It is a sequence chart in the 2nd Embodiment of this invention. It is a flowchart of the deterioration discrimination function calculation part in the 2nd Embodiment of this invention. It is an example of the area code in the 2nd Embodiment of this invention. It is the relationship between the prediction value of area quality by the line function in the 2nd Embodiment of this invention, and actual area quality.

[First Embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an example of a system configuration in the first embodiment of the present invention.

The present invention estimates whether or not there is a large variation in communication quality at the current location on the user terminals 100 _{1 to} 100 _n side in a certain area, and measures the area quality management server 200 only when the variation is estimated to be large. Send a report. The area quality management server 200 is outside the scope of the present invention, but the area quality management server 200 is a general server introduced by each mobile carrier and has been transmitted from the user terminals 100 _{1 to} 100 _n. It is assumed that the communication quality measurement report is plotted on a map to grasp the quality information in a plane and detect a poor quality area.

  In the following, the communication quality variation in the area is referred to as “area quality”, and “area quality is degraded” means that the communication quality variation is large.

  FIG. 2 is a configuration example of a user terminal according to the first embodiment of the present invention.

  The user terminal 100A includes a memory 101, a wireless quality information acquisition unit 110, a location information acquisition unit 120, and an area quality degradation estimation unit 130.

  The radio quality information acquisition unit 110 acquires radio quality information at an arbitrary time. The wireless quality information is acquired by acquiring information generated at a predetermined time every fixed time (for example, 1 minute) from the time set by the operator and storing it in the memory 101. An example of the acquired wireless quality information is shown in Table 1.

表１の無線品質情報は、１秒ごとの通信セルのRSRP、隣接セル数、隣接セルのRSRPを含む。また、メモリ１０１は、予め与えられた判別関数(z)も格納するものとする。

The radio quality information in Table 1 includes the RSRP of a communication cell, the number of neighboring cells, and the RSRP of neighboring cells every second. The memory 101 also stores a discriminant function (z) given in advance.

  The location information acquisition unit 120 acquires the current location of the user terminal 100 </ b> A using a location information measurement tool such as GPS (Global Positioning System) or the API (Application Programming Interface) technology of the terminal OS and stores it in the memory 101. To do.

  The area quality degradation estimation unit 130 includes a radio quality feature amount calculation unit 131, an area quality degradation estimation processing unit 132, and a transmission unit 133.

  The wireless quality feature amount calculation unit 131 calculates a feature amount from the wireless quality information acquired by the wireless quality information acquisition unit 110. The feature amount includes the RSRP standard deviation of the communicating cell in a short time (for example, 1 minute), the average number of neighboring cells, the average RSRP ratio between the communicating cell and the neighboring cell, etc. It may be limited to one or more parts.

The area quality degradation estimation processing unit 132 applies the radio quality feature quantity calculated by the radio quality feature quantity calculation unit 131 to a predetermined discriminant function, so that the area quality is degraded at the current location of the user terminal 100A. Estimate whether or not. Specifically, the radio quality feature quantities r _q1 , r _q2 ,... _Are substituted into the discriminant function z = f (r _q1 , r _q2 ,...), And if z> 0, it is determined that the area quality has deteriorated. Otherwise, it is determined that there is no deterioration.

  The transmission unit 133 transmits the measurement report to the area quality management server 200A only when the area quality degradation estimation processing unit 132 determines that the area quality is degraded. Specifically, the estimation result (with deterioration), the wireless quality feature amount, and the position information acquired by the position information acquisition unit 120 are transmitted. The wireless quality information and the information acquisition time when the wireless quality information acquisition unit 110 acquires the wireless quality information may also be transmitted. In this case, an information acquisition time item is added to Table 1.

  The processing of each of the above components will be described in detail below.

  FIG. 3 is a flowchart of processing of the user terminal according to the first embodiment of the present invention.

Step 110) The radio quality information acquisition unit 110 obtains a certain time i (i is an elapsed time from the start of measurement, i.e., i = 0 to 59 for information of 1 minute) as radio quality information from the area where the user terminal 100A exists. Table 1 shows the RSRP _server (i) (dBm) of the cell in communication, the number of adjacent cells N _cell (i) (cells), and the RSRP _neighbor (i) (dBm) of the adjacent cells as the wireless quality information of Store in the memory 101. Further, the acquisition time of the information may be stored in the memory 101. Further, the position information acquisition unit 120 acquires the position information of the user terminal 100 </ b> A using GPS or the like and stores it in the memory 101.

  Step 120) The radio quality feature quantity calculation unit 131 reads radio quality information from the memory 101. For example, it is assumed that the wireless quality information for one minute shown in Table 1 is read. If the standard deviation of the RSRP of the communicating cell, the average number of neighboring cells, and the average RSRP ratio of the communicating cell and the neighboring cell are used as the wireless quality feature amount, the wireless quality feature amount at this time is obtained as follows. It is done.

・ RSRP standard deviation r _q1 of the cell in communication:
Since it is normally displayed in dBm units, in this embodiment, the standard deviation is obtained after conversion to mW units, and is converted again to dBm.

但し、

However,

・平均隣接セル数r _q2:

・ Average number of neighboring cells r _q2 :

・通信中セルと隣接セルの平均RSRP比r _q3：
本発明の第１の実施の形態では、通信中セルと隣接セルの平均RSRPを求めてから、その比を算出することとする。なお、i秒目に隣接セルが複数ある場合は、そのうち最も大きなRSRP値を

-Average RSRP ratio r _q3 between the cell in communication and the neighboring cell:
In the first embodiment of the present invention, an average RSRP between a cell in communication and an adjacent cell is obtained, and then the ratio is calculated. If there are multiple neighboring cells at i seconds, the largest RSRP value is selected.

とする。また、i秒目に隣接セルがない場合は

And If there is no neighboring cell at i seconds,

とする。

And

但し、

However,

ステップ１３０） エリア品質劣化推定処理部１３２は、上記のステップ１２０で算出された通信中セルのRSRPの標準偏差r _q1(−97.8dBm）、平均隣接セル数r_q2（2.9個）、通信中セルと隣接セルの平均RSRP比r _q3（−2.8dBm）と、
判別関数z=3.07＋0.038r_q1＋0.067r_q2−0.020r_q3
が与えられたものとする。このとき、
z=3.07＋0.038＊(−97.8)+0.067＊2.9−0.020＊(−2.8)=−0.44<0
となるので、当該エリアの品質は劣化していないと推定される。

Step 130) The area quality degradation estimation processing unit 132 calculates the RSRP standard deviation r _q1 (−97.8 dBm) of the cell in communication calculated in Step 120 above, the average number of neighboring cells r _q2 (2.9 cells), and the cell in communication And the average RSRP ratio r _q3 (−2.8 dBm) of neighboring cells,
Discriminant function z = 3.07 + 0.038r _q1 + 0.067r _q2 −0.020r _q3
Is given. At this time,
z = 3.07 + 0.038 * (− 97.8) + 0.067 * 2.9−0.020 * (− 2.8) = − 0.44 <0
Therefore, it is estimated that the quality of the area has not deteriorated.

  Step 140) When the estimation result obtained in Step 130 is “deteriorated”, the transmission unit 133 assigns the area information acquired by the position information acquisition unit 120 and provides the area quality management server 200A as a measurement report. Send to. Note that not only the estimation result but also the radio quality information acquired by the radio quality feature quantity and radio quality information acquisition unit 110 and stored in the memory 101 may be transmitted together.

  Thus, by transmitting only when the estimation result is “degraded”, it becomes possible to reduce traffic between the user terminal 100A and the area quality management server 200A.

[Second Embodiment]
In the area quality degradation estimation unit 130 in the first embodiment, the determination function given in advance is used. However, in the second embodiment of the present invention, the user terminal 100A uses the radio quality feature value and the position. In addition to the information, the communication quality is acquired, and the wireless quality feature amount obtained by the wireless quality feature amount calculation unit 131 is transmitted and stored together with the estimation result to the area quality management server 200A, and the discriminant function is derived using these. To do.

  FIG. 4 is a system configuration example according to the second embodiment of the present invention.

  4, the same components as those in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted.

  The area quality management server 200B according to the second embodiment of the present invention includes a transmission / reception unit 210 that receives a radio quality feature quantity from the user terminal 100B, and a radio quality feature quantity storage unit 220 that stores the radio quality feature quantity. .

  In addition to the configuration of FIG. 2, the user terminal 100 </ b> B includes a communication quality acquisition unit 140 and a deterioration determination function calculation unit 134 in the area quality deterioration estimation unit 130.

  FIG. 5 is a sequence chart according to the second embodiment of the present invention.

  Step 201) The radio quality information acquisition unit 110 acquires radio quality information by the same method as in the first embodiment of the present invention and stores it in the memory 101. The location information acquisition unit 120 acquires location information and stores it in the memory 101 as in the first embodiment of the present invention.

  Step 202) The communication quality acquisition unit 140 acquires an estimated value of communication quality by an arbitrary method and stores it in the memory 101. The estimated value of communication quality may be obtained by using a general network analysis tool, or Non-Patent Document 5 (Tenma Nakamura, Hideki Nojiri, Satoshi Takahashi, “Examination of Throughput Estimation Method by Passive Measurement in User Terminal”) , Shingaku Sodai, 2013-9). As an index indicating communication quality, throughput may be used, or RTT (Round Trip Time), loss rate, or the like may be used. Note that the estimated value of the communication quality may not be obtained constantly, and may be obtained only at a specific user terminal or in a specific area or time zone.

  Step 203) The deterioration determination function calculation unit 134 acquires the wireless quality feature quantity already stored in the area quality management server 200B and stores it in the memory 101.

  Table 2 shows an example of information stored in the memory 101 by the processing so far. Each area (area codes A to K) in Table 2 is an example in which the latitude and longitude are divided into 0.0008 degrees (about 100 m).

メモリ１０１には、エリアコード、データ整理番号、上記で取得した無線品質特徴量、ステップ２０２で取得した通信品質の推定値、位置情報取得部１２０で取得した位置情報が格納される。

The memory 101 stores an area code, a data reference number, the wireless quality feature value acquired above, the estimated communication quality acquired at step 202, and the position information acquired by the position information acquisition unit 120.

  Step 204) The degradation determination function calculation unit 134 uses the past wireless quality feature amount in each area acquired from the area quality management server 200B in Step 203 and the estimated communication quality acquired in Step 202 to reduce the area quality degradation. A discriminant function is calculated.

  Note that the processing of step 203 and step 204 is not limited to being performed at this point in the sequence chart of FIG. 5, and may be performed at any timing as long as it is before execution of step 206. For example, it is conceivable to acquire the wireless quality feature amount every predetermined cycle or triggered by the information storage amount in the wireless quality feature amount storage unit 220 of the area quality management server 200B becoming a predetermined value or more. It is done.

  FIG. 6 is a flowchart of the process of the deterioration determination function calculation unit in the second embodiment of the present invention.

  Step 301) The degradation determination function calculation unit 134 obtains the magnitude of the communication quality variation for each area and stores it in the memory 101. The communication quality variation may be represented by a standard deviation or variance, or may be represented by a difference between a maximum value and a minimum value. In addition, the “area” here may be defined by dividing the target area by an arbitrary distance, or may be defined by a standard area mesh or the like determined by the Ministry of Internal Affairs and Communications.

  Step 302) If the magnitude (v) of the communication quality variation in each area obtained above is larger than the predetermined threshold value (th), the process proceeds to Step 303. Otherwise, the process proceeds to Step 304. Transition.

  Step 303) If v> th, it is determined that the deterioration is “1”, and the process proceeds to Step 305.

  Step 304) If v ≦ th, it is determined that there is no deterioration “0”, and the routine proceeds to Step 305.

  Step 305) The above area quality evaluation results “1” and “0” are subjected to discriminant analysis using the objective variable and the radio quality feature quantity as explanatory variables, and the obtained discriminant function is stored in the memory 101. The method of discriminant analysis is not particularly limited. For example, a linear function, a nonlinear function, a decision tree, or the like can be used. A specific example of calculating the discriminant function (z) will be described later.

  It should be noted that the discriminant function is repeatedly derived by elapse of a certain time or a certain amount of stored data in the area quality management server 200B, and when there is no stored data, the first embodiment of the present invention Similarly to the above, a predetermined discriminant function is used.

  Step 205) The radio quality feature quantity calculation unit 131 calculates the radio quality feature quantity by the same method as in the first embodiment of the present invention.

  Step 206) The area quality degradation estimation processing unit 132 reads out the discriminant function calculated in Step 204 from the memory 101, and estimates area quality degradation using the same method as in the first embodiment of the present invention.

  Step 207) The transmission unit 133 reads out the communication quality obtained in Step 202 and the wireless quality feature quantity calculated in Step 205 from the memory 101, and transmits them to the area quality management server 200B together with the obtained estimation result of the area quality degradation. To do.

  Step 208) The area quality management server 200B stores the radio quality feature quantity in the radio quality feature quantity storage unit 220.

  Hereinafter, the process of FIG. 6 performed by the deterioration determination function calculation unit 134 will be described in detail.

  For example, it is assumed that a set of past wireless quality feature amounts, communication quality, and position information in each area shown in Table 2 is stored in the feature amount storage unit 220 of the area quality management server 200B.

  At this time, the area quality in each area is evaluated as shown in Table 3.

なお、本発明の第２の実施の形態では、通信品質のばらつきの大きさを、スループットの最大値と最小値の差で表した。また、通信品質のばらつきの大きさの閾値は6000kbpsとした。また、表３に示されるエリアコードの実際のエリアを図７に示す。

In the second embodiment of the present invention, the magnitude of the communication quality variation is represented by the difference between the maximum value and the minimum value of the throughput. In addition, the threshold value of the variation in communication quality is set to 6000 kbps. Moreover, the actual area of the area code shown in Table 3 is shown in FIG.

  For example, in the case of area A, the past throughput values in the area are 4260, 5140, 5820, 8720 (kbps), the maximum value is 8720, and the minimum value is 4260. Therefore, since the magnitude of the variation in throughput is 8720-4260 = 4460 (kbps) <6000, the area quality of area A is evaluated as “0” (not degraded) (steps 301 to 304).

  Next, it is assumed that the area quality evaluation result and the wireless quality feature amount in each area shown in Tables 2 and 3 are input to the deterioration determination function calculation unit 134. At this time, the discriminant function z is obtained as follows (step 305).

z = 3.07 + 0.038 r _q1 +0.067 r _q2 −0.020 r _q3
Here, r _q1 , r _q2 , and r _q3 are radio quality feature quantities, and indicate the RSRP standard deviation, the average number of neighboring cells, and the average RSRP ratio between the communicating cell and neighboring cells, respectively. In the second embodiment of the present invention, the discriminant function is assumed to be linear and is obtained by the following procedure.

(1) A multiple regression analysis is performed using the area quality a _q as an objective function and the radio quality features r _q1 , r _q2 , r _q3 as explanatory variables to obtain the following regression function.

a _q = 3.59 + 0.038r _q1 + 0.067r _q2 −0.020 r _q3
(2) The predicted area quality value by the regression function and the actual area quality are plotted, and a discrimination boundary with the highest discrimination correct answer rate is obtained as shown in FIG. In the case of FIG. 8, since the discrimination correct answer rate is the highest when the discrimination boundary is between 0.50 and 0.53, this time the discrimination boundary is set to 0.52.

  (3) From the above (1) and (2), the discriminant function z is obtained as follows.

z = 3.59 + 0.038r _q1 + 0.067r _q2 +0.020 r _q3 −0.52
= 3.07 + 0.038r _q1 + 0.067r _q2 −0.020 r _q3
In the second embodiment of the present invention described above, an example is shown in which the area quality management server 200B holds the wireless quality feature quantity and the communication quality obtained by the user terminal 100B. However, the present invention is not limited to this example. Instead, it may be stored in a storage means such as an external database system, and read out from the storage means when calculating a discriminant function for area quality degradation.

  Further, the process of the degradation determination function calculation unit 134 of the user terminal 100B may be executed by a device outside the user terminal 100B.

<Evaluation of the present invention>
The validity of the estimation result of the area quality degradation using the present invention is as follows.

  The evaluation objects are the radio quality feature amounts and area quality evaluation results in each area shown in Tables 2 and 3. Data of area codes G to K is set as a learning data set, and data of A to F is set as an estimation data set.

  And the estimation precision by this invention was evaluated with the following procedures.

  (1) Using the wireless quality feature quantity and area quality of areas G to K, the discriminant function z for area quality degradation is calculated as follows according to the present invention.

z = 0.022r _q1 + 0.26r _q2 −0.056 r _q3 +0.83
(2) The area quality degradation of areas A to F is estimated using the radio quality feature quantities of areas G to K and the discriminant function calculated in (1).

  (3) The actual measured values of area quality in areas A to F and the predicted value of area quality estimated in (2) are shown (FIG. 8).

  In the present invention, the operation of the user terminals 100A and 100B can be constructed as a program and installed in a terminal used as an area quality degradation estimation apparatus, or can be distributed via a network.

  The present invention is not limited to the above-described embodiment, and various modifications and applications can be made within the scope of the claims.

100 _{1 to} 100 _n , 100A, 100B User terminal 101 Memory 110 Radio quality information acquisition unit 120 Location information acquisition unit 130 Area quality degradation estimation unit 131 Radio quality feature amount calculation unit 132 Area quality degradation estimation processing unit 133 Transmission unit 134 Degradation determination Function calculation unit 200, 200A, 200B Area quality management server 210 Transmission / reception unit 220 Wireless quality feature amount storage unit

Claims (8)

An area quality degradation estimation apparatus that estimates degradation of area quality indicating that communication quality variation is large in an arbitrary area of a wireless system,
Wireless quality information acquisition means for storing the acquired wireless quality information in the storage means;
Position information acquisition means for acquiring position information of the device;
Radio quality feature quantity calculating means for calculating a radio quality feature quantity (hereinafter referred to as “radio quality feature quantity”) from the radio quality information;
Area quality deterioration estimation means for determining communication quality deterioration from variations in communication quality in the area indicated by the position information, using the wireless quality feature amount and a discriminant function for determining area quality deterioration;
When the area quality degradation estimation unit determines that the communication quality is largely varied and the communication quality is degraded, the transmission unit transmits information about the quality degradation to the server as a measurement report;
An area quality deterioration estimation device characterized by comprising: The area quality degradation estimation means includes
2. The area quality deterioration estimation apparatus according to claim 1, wherein a discriminant function given in advance and stored in the storage means is used. The transmission means includes
The measurement report includes means for transmitting including the wireless quality feature quantity and the wireless quality information,
The area quality degradation estimation apparatus according to claim 1, further comprising means for acquiring the wireless quality feature quantity and the wireless quality information stored in the server and calculating the discriminant function. The wireless quality feature amount calculating means includes:
As the radio quality feature amount, any one of RSRP (Reference Signal Received Power) standard deviation of cells in communication in an arbitrary time range, average number of adjacent cells, average RSRP ratio of cells in communication and adjacent cells, or those The area quality degradation estimation apparatus according to claim 1, wherein a combination of the above is used. An area quality degradation estimation method for estimating degradation of area quality indicating that a variation in communication quality in an arbitrary area of a wireless system is large,
Storage means;
Wireless information acquisition means;
Position information acquisition means for acquiring position information of the device;
In an apparatus having a radio quality feature amount calculating means, an area quality deterioration estimating means, and a transmitting means,
The wireless quality information acquisition unit stores the acquired wireless quality information in the storage unit;
A wireless quality feature amount calculating step in which the wireless quality feature amount calculating means calculates a wireless quality feature amount (hereinafter referred to as “wireless quality feature amount”) from the wireless quality information;
Area quality in which the area quality degradation estimation means determines communication quality degradation from a variation in communication quality in the area indicated by the position information, using the wireless quality feature quantity and a discriminant function for discriminating area quality degradation. A degradation estimation step;
When the transmission means determines that the communication quality is largely varied in the area quality degradation estimation step and the communication quality is degraded, a transmission step of transmitting information relating to the quality degradation to the server as a measurement report;
An area quality degradation estimation method characterized by performing: In the area quality degradation estimation step,
6. The area quality deterioration estimation method according to claim 5, wherein a discriminant function given in advance and stored in the storage means is used. In an apparatus further comprising a determination function calculation means,
In the transmission step, the measurement report is transmitted including the wireless quality feature amount and the wireless quality information,
The area quality degradation estimation method according to claim 5, wherein the discriminant function calculating unit further acquires the radio quality feature quantity and the radio quality information stored in the server and calculates the discriminant function. In the wireless quality feature amount calculating step,
As the radio quality feature amount, any one of RSRP (Reference Signal Received Power) standard deviation of cells in communication in an arbitrary time range, average number of adjacent cells, average RSRP ratio of cells in communication and adjacent cells, or those The area quality degradation estimation method according to claim 5 using a combination of the above.

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