Method for estimating distribution of radio wave intensity received by wireless base station and method for redesigning antenna

Abstract

To provide a technique capable of accurately estimating a received electric field intensity distribution for grasping capability of a wireless base station.SOLUTION: An estimation method of a received radio wave intensity distribution of a wireless base station includes a first step of acquiring data on received radio wave intensity measured by a radio wave receiver mounted on a vehicle traveling within a target area, a second step of calculating a spatial propagation loss using a plurality of types of model formulas for calculating the spatial propagation loss using specification information of a target wireless base station as input information to calculate a received radio wave intensity distribution, a third step of selecting, from among the plurality of received radio wave intensity distributions calculated in the second step, a received radio wave intensity distribution whose change trend is closest to a the received radio wave intensity distribution obtained in the first step, and a fourth step of determining an estimated received radio wave intensity distribution by moving the received radio wave intensity distribution selected in the third step and matching the same with the received radio wave intensity distribution acquired in the first step.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for estimating the distribution of radio wave intensity received by a wireless base station in a wireless communication system and a method for redesigning an antenna, and relates to a technology that is effective when applied to a wireless communication system called train radio used for communication between train crew members and a commander at a train operation control center or the like. [Background technology]

[0002] Traditionally, analog train radio, which transmits information via analog signals, has been the norm for railway train radio, but in recent years, construction is underway to replace it with digital train radio, which transmits information via digital signals. When changing train radio from analog to digital, it has been common to keep the aerials (antennas) as they are. Representative examples of aerials (antennas) for train radio include array antennas such as Yagi antennas and LCX cables (leaky coaxial cables).

[0003] On the other hand, since the communication quality was improved when the system was digitized, there are some places where the antennas are excessive. Therefore, continuing to use the antennas used in analog train radio after the system is digitized may be inefficient in terms of maintenance and cost, so reviewing the antennas is expected to improve life cycle costs. In particular, since the LCX cable is a long cable laid along the tracks, it is less susceptible to radio interference, but has the characteristic of being inefficient in maintenance, so a review is meaningful.

[0004] In order to redesign an antenna, it is necessary to accurately grasp the distribution of the received electric field strength by the existing antenna. On the other hand, currently, when designing an antenna for the first time, a method of calculating the spatial propagation loss using a model formula or a method of calculating the spatial propagation loss by simulation are adopted. Therefore, when redesigning an antenna, it is possible to use a method to calculate the spatial propagation loss using a model formula or simulation. However, the method using a model formula is simple, but the difference from the actual value is large. In addition, the method using a simulation is highly accurate, but requires a lot of labor and time, which increases the cost. On the other hand, as an example of an invention relating to a technique for creating received electric field strength distribution data, there is one described in Patent Document 1. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2002-112303 A [Patent Document 2] JP 2017-143487 A [Patent Document 3] Japanese Patent Application Publication No. 07-087557 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the invention of Patent Document 1, the control unit of the wireless mobile terminal creates reception field strength distribution data for the terminal's current location and its surroundings based on reception field strength information from wireless base stations and location information transmitted from GPS satellites, and there is an issue that it is difficult to obtain a reception field strength distribution that is sufficient to grasp the capabilities of wireless base stations over a wide range. In addition, the invention of Patent Document 1 discloses using the created reception electric field strength distribution data to display a reception electric field strength distribution map and the position of a terminal, but does not disclose using it to redesign the antenna of a wireless base station.

[0007] On the other hand, for example, Patent Document 2 describes an invention relating to a layout design support device and method capable of estimating the optimal location of a wireless base station, while Patent Document 3 describes an invention relating to a method for automatically determining the optimal layout location of an indoor cordless telephone base station so that radio waves can reach the entire interior of a specified building. However, Patent Document 2 discloses a technique for calculating the optimal base station position when a new wireless base station is to be placed in a specific area of ​​interest, but does not disclose a technique for redesigning the antenna of the wireless base station. Also, Patent Document 3 discloses a technique for determining the optimal placement position of an indoor cordless telephone base station in a specified building, but does not disclose determining the optimal placement position of a wireless base station by estimating the distribution of received radio wave strength of outdoor wireless communication, which has completely different conditions.

[0008] The present invention has been made against the background described above, and has an object to provide a technique for calculating the spatial propagation loss due to the antenna of a wireless base station based on information from the wireless base station, and for simply and accurately estimating the received electric field strength distribution in order to grasp the capabilities of the wireless base station. Another object of the present invention is to provide a technique for redesigning the antenna of a wireless base station by finding a wireless base station that can be removed or a wireless base station in which an LCX cable can be replaced with an antenna. [Means for solving the problem]

[0009] In order to achieve the above object, the present invention provides A method for estimating a received radio wave intensity distribution of a wireless base station in a wireless communication system having a plurality of wireless base stations that transmit and receive wireless signals, comprising: A first step of acquiring data on received radio wave strength measured by a radio wave receiver mounted on a vehicle traveling within a target area; a second step of calculating spatial path loss using a plurality of model formulas for calculating spatial path loss using specification information of a wireless base station of interest as input information, and calculating a received radio wave intensity distribution; a third step of selecting, from among the plurality of received radio wave intensity distributions calculated in the second step, a received radio wave intensity distribution having a change tendency closest to the distribution of the received radio wave intensity acquired in the first step; a fourth step of determining an estimated received radio wave strength distribution by shifting the received radio wave strength distribution selected in the third step to match the distribution of the received radio wave strength acquired in the first step; The above is included.

[0010] According to the method of the above procedure, the spatial propagation loss due to the antenna of the wireless base station is calculated by the model formula, so that the spatial propagation loss can be calculated based on the specification information of the wireless base station. In addition, the reception electric field strength distribution of the wireless base station is selected and determined from a plurality of reception electric field strength distributions obtained from the spatial propagation loss by the plurality of model formulas in this way, so that the reception electric field strength distribution can be estimated simply and accurately.

[0011] The invention of the radio base station antenna redesign method according to the present application is as follows: An antenna redesign method for redesigning an antenna of a wireless base station based on the received radio wave intensity distribution estimated by the received radio wave intensity distribution estimation method, comprising the steps of: With respect to an area in which an existing first radio base station, an existing second radio base station, and an existing third radio base station located between the first radio base station and the second radio base station are present, estimating a first reception radio wave intensity distribution of the first radio base station and a second reception radio wave intensity distribution of the second radio base station by the first to fourth steps; Based on the estimated first received radio wave strength distribution and the estimated second received radio wave strength distribution, if the received radio wave strength at all positions between the first radio base station and the second radio base station is not below a predetermined allowable received electric field strength, it is determined that the third radio base station can be removed. According to this method, it is possible to relatively easily examine whether or not a third wireless base station arranged between two wireless base stations can be removed.

[0012] In addition, another invention of an antenna redesign method according to the present application is as follows: An antenna redesign method for redesigning an antenna of a wireless base station based on the received radio wave intensity distribution estimated by the received radio wave intensity distribution estimation method, comprising the steps of: With respect to an area in which an existing first radio base station, an existing second radio base station, and an existing third radio base station located between the first radio base station and the second radio base station exist, the aerials of the first radio base station and the second radio base station are aerial antennas, and the aerial of the third radio base station is an LCX cable, After estimating the first reception radio wave intensity distribution of the first radio base station and the second reception radio wave intensity distribution of the second radio base station by the first to fourth steps, a fifth step of determining a first correction value and a second correction value according to the amount of movement caused by the movement process in the fourth step; a sixth step of calculating a spatial propagation loss of a third radio base station between the first radio base station and the third radio base station using a first model equation corresponding to the first received radio wave intensity distribution selected in the third step, and calculating a third received radio wave intensity distribution corrected with a third correction value calculated by a predetermined correction value calculation equation having the first correction value and the second correction value determined in the fifth step as variables; a seventh step of calculating a spatial propagation loss of a third radio base station between the second radio base station and the third radio base station using a second model equation corresponding to the second received radio wave intensity distribution selected in the third step, and calculating a fourth received radio wave intensity distribution corrected by the third correction value calculated in the sixth step; Based on the third received radio wave intensity distribution calculated in the sixth step and the fourth received radio wave intensity distribution calculated in the seventh step, if the received radio wave intensity at all positions between the first radio base station and the second radio base station is not below a predetermined allowable received electric field intensity, it is determined that the antenna of the third radio base station can be replaced with an air antenna. According to this method, it is possible to relatively easily consider whether the antenna of a third wireless base station located between two wireless base stations can be replaced from an LCX cable to an air antenna.

[0013] Here, when distances from an arbitrary point to the first radio base station, the second radio base station, and the third radio base station are respectively x, y, and z, the first correction value is a, the second correction value is c, and the third correction value is b, the correction value calculation formula in the sixth step is b={(zy)a / (zx)}+{(yx)c / (zx)} Use the following. According to a method using such a correction value calculation formula, the antenna of a wireless base station can be redesigned simply and accurately. In addition, the above antenna redesign method is effective when applied to a case where the wireless communication system is a wireless communication system for a railway line, and the first wireless base station, the third wireless base station, and the second wireless base station are wireless base stations arranged in sequence along the railway track. Effect of the Invention

[0014] According to the reception electric field strength distribution estimation method of the present invention, it is possible to calculate the spatial propagation loss due to the antenna of an existing wireless base station based on the information of the wireless base station, and to simply and accurately estimate the reception electric field strength distribution for grasping the capability of the wireless base station. Also, according to the wireless base station antenna redesign method of the present invention, it is possible to find a base station that can be removed or a wireless base station in which an LCX cable can be replaced with an antenna, and thus to redesign the antenna of the wireless base station. [Brief description of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing an example of the configuration of a train radio system to which the reception electric field strength distribution estimation method and the antenna redesign method and system of a radio base station according to the present invention can be effectively applied; [Diagram 2]Graph (A) shows the relationship between the position of a radio base station in a train radio system and the actual measured value of received radio wave strength, and graph (B) shows the received electric field strength distribution of the antennas of two radio base stations determined by the received electric field strength distribution estimation method of the embodiment and the actual measured value of received radio wave strength. [Diagram 3] 11 is a graph sequentially showing a process of selecting the reception electric field strength distribution that best matches an actual measurement value from among the reception electric field strength distributions calculated using a plurality of model formulas by the reception electric field strength distribution estimating method according to the embodiment. [Figure 4] 1 is an explanatory diagram showing the arrangement of wireless base stations in an area to which the antenna redesign method for a wireless base station according to the present invention is applied; [Diagram 5] Graph (A) is a graph showing the relationship between the positions of two radio base stations in a train radio system, the actual measured values ​​of received radio wave strength, and the received electric field strength distribution of the antennas of the two radio base stations determined by the received electric field strength distribution estimation method of the embodiment, and graph (B) is a graph in which the estimated received electric field strength distribution of the antenna of the intermediate radio base station is added to graph (A). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, with reference to the drawings, embodiments of a method for estimating a distribution of a received electric field strength and a method for redesigning an antenna of a wireless base station according to the present invention will be described. FIG. 1 is a diagram showing a schematic configuration of a train radio system as a radio communication system to which the method of the present invention can be effectively applied.

[0017] As shown in Fig. 1, the train radio system is composed of a number of radio base stations 10A, 10B, 10C ... (hereinafter referred to as radio base station 10 when there is no need to distinguish between them) arranged at appropriate distances along a railway track 100, an on-board radio communication device 21 mounted on a vehicle 20 running on the track, and a ground-side communication device 31 used by a dispatcher such as a train operation control center 30 to monitor train operation on a specified line or train operation status on multiple lines in a specified area and issue commands to each train. The on-board radio communication device 21 and the ground-side communication device 31 have the function of allowing train crew and dispatchers to talk and send and receive data by radio communication via the radio base station 10.

[0018] The wireless base stations 10A, 10B, 10C, etc. are provided with aerials (antennas) 11A, 11B, 11C, etc. (hereinafter referred to as antennas 11 when there is no need to distinguish between them) for transmitting and receiving radio waves, and wireless transceivers 12A, 12B, 12C, etc. In addition, the antenna 11 in the current train radio system is generally an array antenna such as a Yagi antenna, but there are also cases where an LCX cable (leaky coaxial cable) laid along the track is used in some sections.

[0019] Next, two methods for redesigning the radio base station 10 in the train radio system shown in FIG. 1 will be specifically described. The first method utilizes data on received radio wave strength measured by an electrical inspection vehicle traveling on the route in question to estimate the received electric field strength distribution (received electric field strength versus distance) of radio signals transmitted from existing wireless base stations 10 that use an aerial antenna (other than an LCX cable) 11, and by accurately grasping the capabilities of the wireless base stations 10, this can be used to find wireless base stations that can be removed.

[0020] In addition, electrical inspection cars run on major railway lines periodically to measure various data on track facilities (including train radio reception signal strength) and record them in storage devices, so for such lines, data on the reception signal strength of a desired section can be extracted from the stored data and used. The train radio reception signal strength may be collected by installing a dedicated radio receiver on a commercial train running on the line.

[0021] However, the actual measured value of the received electric field strength obtained by the inspection vehicle varies drastically depending on the distance from the radio base station due to various obstacles along the track such as the terrain, buildings, vegetation, etc., as shown in Figure 2 (A), so it is not possible to accurately grasp the communication capacity of the radio base station. On the other hand, as mentioned above, there is a known method of calculating the spatial propagation loss using a model formula when initially designing an antenna, and various model formulas have been proposed according to the communication environment.

[0022] Therefore, in this embodiment, the spatial propagation loss (theoretical value) is calculated for a radio signal transmitted from a radio base station of interest using a plurality of model formulas, the received electric field strength distribution is obtained from the calculated spatial propagation loss, and the distribution with the closest change tendency (slope and curvature) is selected in comparison with the distance versus received electric field strength based on data on radio field strength measured by a radio wave receiver mounted on an inspection vehicle or the like, and the selected received electric field strength distribution is moved on a graph to obtain a shift amount for matching it with the actual measured value by the inspection vehicle or the like. Note that although the spatial propagation loss is calculated using the model formula, if the spatial propagation loss is known, the received electric field strength can be calculated by performing a simple subtraction.

[0023] As an example, Figure 3(A) shows the actual value (wavy line A) measured by an inspection vehicle for an existing digital wireless base station, curve B of the spatial propagation loss calculated using a well-known model equation for spatial propagation in free space, curve C of the spatial propagation loss calculated using a model equation for spatial propagation in free space called the Egli model, and curve D of the spatial propagation loss calculated using a model equation for spatial propagation in free space called the Okumura-Hata model.

[0024] In addition, the spatial propagation loss according to the above model formula can be easily calculated using a propagation loss calculation tool (software) that can output the spatial propagation loss as a calculation result by selecting one of several model formulas and inputting the base station specifications such as the frequency used, antenna height, transmission power, and transmitting antenna gain, which are listed on the radio station license, and the mobile station specifications such as the distance, mobile station antenna height, receiving antenna height, and receiving antenna gain.

[0025] When Fig. 3(A) is examined, it can be seen that the change tendency of curve C of the spatial path loss calculated by the Egli model shown in Fig. 3(B) is closest to the actual measurement value A. Therefore, as shown in Fig. 3(C), a process is performed to move curve C so that it matches the actual measurement value A, and the curve is used as the estimated received electric field strength distribution of the wireless signal transmitted from the wireless base station. In addition to the above three models, other spatial propagation models are known, such as the Sakagami model, the Walfisch-Ikegami model, the Kaji model, and the Ichitsubo model, and each of these has a model formula for calculating spatial propagation loss. Therefore, from among the curves of the reception electric field strength distribution based on the spatial propagation loss calculated using these model formulas, the one whose change trend is closest to the actual measured value may be selected as the estimated reception electric field strength distribution.

[0026] When considering whether it is possible to remove the intermediate wireless base station Y among the existing wireless base stations X, Y, and Z, the above-mentioned method is used to calculate the distance vs. reception field strength curves for the wireless base stations X and Z. Figure 2(B) shows examples of the calculated distance vs. reception field strength curves Ex, Ey. In Fig. 2(B), at all positions between the wireless base stations X and Z, it is determined whether the reception electric field strength of the wireless signal transmitted from the wireless base station X or Z exceeds the allowable reception electric field strength (minimum reception electric field strength) ESt. If the reception electric field strength exceeds the allowable reception electric field strength ESt at all positions, it can be determined that the wireless base station Y can be removed, and if the reception electric field strength is below the allowable reception electric field strength ESt at any position, it can be determined that the wireless base station Y cannot be removed. This method can be applied to both cases where the antenna of the wireless base station Y is an aerial antenna or an LCX cable.

[0027] Next, a procedure will be described for using the second method to determine whether it is possible to replace the LCX cable with an aerial antenna (Yagi antenna) when the antenna of the intermediate wireless base station Y is an LCX cable for existing wireless base stations X, Y, and Z installed at distances x, y, and z from an arbitrary point (kilometers in the case of a railway line) as shown in Fig. 4. Note that, although Fig. 4 shows that the track 100 is straight and the wireless base stations X, Y, and Z are arranged side by side on a straight line, the track 100 may be curved and the wireless base stations X, Y, and Z may be arranged side by side on a curve.

[0028] In the second method, first, the spatial propagation loss is calculated using a number of models for the existing wireless base stations X and Z at the locations according to the first method described above, and the received electric field strength is calculated. The model that is closest to the actual measured value is selected to determine the distance vs. received electric field strength curve as shown by Ex and Ez in Fig. 5(A). The shift amount at this time is determined as correction values ​​a and c. Note that the correction values ​​a and c have a negative sign when the curve of the graph is shifted downward, and a positive sign when the curve is shifted upward.

[0029] When the intermediate portion of the actual measurement value A in the graph of Fig. 5(A) includes the received electric field strength of the radio waves transmitted from the LCX cable of the wireless base station Y, it is preferable to determine Ex and Ez by comparing the waveforms of the actual measurement value A at the portions close to the wireless base stations X and Z. In addition, since there are no obstacles between the antenna and the vehicle, the received electric field strength of the radio waves transmitted from the LCX cable can be obtained with high accuracy by calculation or actual measurement, so that the value obtained by subtracting the received electric field strength of the LCX cable from the actual measurement value A may be used as the net received electric field strength of the wireless base stations X and Z.

[0030] Next, as shown in Fig. 5(B), distance vs. reception electric field strength curves Ey1 and Ey2 are estimated in case the LCX cable of wireless base station Y is replaced with an air antenna, and at this time, if the model formula obtained from Ex is different from the model formula obtained from Ez, the same model formula as the pre-shift model formula used when determining the distance vs. reception electric field strength curve Ex of wireless base station X is used for Ey1, and the same model formula as the pre-shift model formula used when determining the distance vs. reception electric field strength curve Ez of wireless base station Z is used for Ey2. Incidentally, in many cases, the model formula of Ex is the same as the model formula of Ez.

[0031] Next, the correction value b of each model formula is expressed as the following formula using the above correction values ​​a and c as variables. b={(zy)a / (zx)}+{(yx)c / (zx)} ……(1) and correcting it with this correction value b to obtain the distance vs. received field strength curves Ey1, Ey2 of the wireless base station Y. Specifically, if the curve equations of Ey1, Ey2 before correction are expressed as f(y1), f(y2), Ey1, Ey2 after correction become f(y1)+b, f(y2)+b. In the above explanation, the correction value calculation formula (1) means that the correction value b is obtained by taking the sum of the value (first term) obtained by dividing a proportionally based on the ratio of the distance zx between the wireless base stations X and Z to the distance zy between the wireless base stations Y and Z, and the value (second term) obtained by dividing c proportionally based on the ratio of the distance zx between the wireless base stations X and Z to the distance yx between the wireless base stations Y and X.

[0032] Once the distance-versus-reception field strength curves Ey1, Ey2 of the wireless base station Y have been obtained as described above, it is determined whether the reception field strength is below a predetermined allowable reception field strength ESt at all positions between the wireless base stations XZ, and if it is not below, it is determined that the LCX cable of the wireless base station Y can be replaced with an aerial antenna, and if it is below, it is determined that the LCX cable of the wireless base station Y cannot be replaced with an aerial antenna.

[0033] As described above, according to the second method, for existing wireless base stations X, Y, and Z, when the antenna of the intermediate wireless base station Y is an LCX cable, it is possible to determine whether the LCX cable can be replaced with an aerial antenna. Also, it is possible to determine that the antenna of wireless base station Y cannot be removed, but the LCX cable can be replaced with an aerial antenna.

[0034] The invention made by the present inventor has been specifically described above based on the embodiment, but the present invention is not limited to the above embodiment. For example, the above embodiment has been described assuming the study of an antenna of a radio base station in a digital train radio, but the present invention is not limited to train radio, and can also be applied to the study of increasing the output of a base station in a radio communication system for train approach warning, for example, which transmits train approach information detected by a track circuit to a receiver held by a ground worker and sounds the alarm.

[0035] Furthermore, in the above embodiment, the present invention has been described as being applied to a wireless communication system for railway lines. However, the present invention is not limited to wireless communication systems for railway lines, and can be applied to wireless communication systems, such as expressways and dedicated bus routes, in which wireless base stations are arranged along a line. [Explanation of symbols]

[0036] 10 Radio base station 20 Vehicles 21 On-board radio communication equipment 30 Operation Control Center 31 Ground communication device

Claims

1. A method for estimating a received radio wave intensity distribution of a radio base station in a wireless communication system including a plurality of radio base stations that transmit and receive radio signals, comprising: A first step of acquiring data on received radio wave strength measured by a radio wave receiver mounted on a vehicle traveling within a target area; a second step of calculating spatial path loss using a plurality of types of model formulas for calculating spatial path loss using specification information of a wireless base station of interest as input information, and calculating a received radio wave intensity distribution; a third step of selecting, from among the plurality of received radio wave intensity distributions calculated in the second step, a received radio wave intensity distribution having a change tendency closest to the distribution of the received radio wave intensity acquired in the first step; a fourth step of determining an estimated received radio wave strength distribution by shifting the received radio wave strength distribution selected in the third step to match the distribution of received radio wave strength acquired in the first step; A method for estimating distribution of received radio wave intensity at a wireless base station, comprising:

2. 2. An antenna redesign method for redesigning an antenna of a wireless base station based on a received radio wave intensity distribution estimated by the method for estimating a received radio wave intensity distribution of a wireless base station according to claim 1, comprising the steps of: With respect to an area in which an existing first radio base station, an existing second radio base station, and an existing third radio base station located between the first radio base station and the second radio base station are present, estimating a first reception radio wave intensity distribution of the first radio base station and a second reception radio wave intensity distribution of the second radio base station by the first to fourth steps; a method for redesigning an antenna of a radio base station, comprising: determining that the third radio base station can be removed when the received radio wave strength at all positions between the first radio base station and the second radio base station is not below a predetermined allowable received electric field strength based on the estimated first received radio wave strength distribution and the estimated second received radio wave strength distribution.

3. 2. An antenna redesign method for redesigning an antenna of a wireless base station based on a received radio wave intensity distribution estimated by the method for estimating a received radio wave intensity distribution of a wireless base station according to claim 1, comprising the steps of: With respect to an area in which an existing first radio base station, an existing second radio base station, and an existing third radio base station located between the first radio base station and the second radio base station exist, the aerials of the first radio base station and the second radio base station are aerial antennas, and the aerial of the third radio base station is an LCX cable, After estimating a first reception radio wave intensity distribution of the first radio base station and a second reception radio wave intensity distribution of the second radio base station by the first to fourth steps, a fifth step of determining a first correction value and a second correction value according to the amount of movement caused by the movement process in the fourth step; a sixth step of calculating a spatial propagation loss of a third radio base station between the first radio base station and the third radio base station by using a first model equation corresponding to the first received radio wave intensity distribution selected in the third step, and calculating a third received radio wave intensity distribution corrected by a third correction value calculated by a predetermined correction value calculation equation having the first correction value and the second correction value determined in the fifth step as variables; a seventh step of calculating a spatial propagation loss of a third radio base station between the second radio base station and the third radio base station using a second model equation corresponding to the second received radio wave intensity distribution selected in the third step, and calculating a fourth received radio wave intensity distribution corrected by the third correction value calculated in the sixth step; and determining, based on the third received radio wave strength distribution calculated in the sixth step and the fourth received radio wave strength distribution calculated in the seventh step, that the antenna of the third radio base station can be replaced with an air antenna when the received radio wave strength at all positions between the first radio base station and the second radio base station is not below a predetermined allowable received electric field strength.

4. When distances from an arbitrary point to the first radio base station, the second radio base station, and the third radio base station are respectively x, y, and z, the first correction value is a, the second correction value is c, and the third correction value is b, the correction value calculation formula in the sixth step is b={(z-y)a / (z-x)}+{(y-x)c / (z-x)} 4. The method for redesigning an antenna of a wireless base station according to claim 3,

5. The wireless communication system is a wireless communication system for a railway line, 5. The method for redesigning an antenna of a radio base station according to claim 4, wherein the first radio base station, the third radio base station, and the second radio base station are radio base stations arranged in sequence along a railway track.

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