JP2010147519A - Radio communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide desired communication environments by autonomously reconstructing radio communication paths by evaluating radio service areas and automatically adjusting radio parameters in a radio communication environment in which movement of people and objects causes a change in radio field strength. <P>SOLUTION: A radio station 1 measures the radio field strength of received radio waves, and notifies a center server of a measurement value and occurrence of change, when comparing the measured radio field strength with past radio field strength to detect a change in the communication environment. The center server 2 estimates a change place in a propagation path of radio waves in a system and factors based on the measurement value notified by the radio station 1, derives a radio parameter suitable for the changed communication environment, and notifies the radio station 1 of the parameter. Also, the center server 2 includes a state display device 24 for displaying the state of the communication environment, and displays places where communication quality has deteriorated, and countermeasures for improving communication quality. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a radio communication system applicable to an environment where there are many reflection paths and the communication environment fluctuates, such as in a plant.

  The introduction of plant instrumentation wireless technology that performs unattended monitoring of a plant by arranging sensors at various work locations in the plant and collecting information measured by each sensor by wireless communication is in progress. In wireless data transmission, there is a decrease in data transmission speed due to reflections and bit errors due to reflections, and interference that occurs due to the introduction of many wireless devices. Therefore, to create a good wireless communication environment, vehicles and surrounding buildings It is necessary to evaluate the influence of the system from the planning and design stage and determine the parameters (location, antenna direction, antenna tilt angle, antenna directivity, frequency, transmission output, modulation method, etc.) of the base station and wireless terminal It becomes.

  Since communication performance greatly depends on the superiority and inferiority of the installation environment, in general, in the design of a wireless communication system, installation that can satisfy the required communication performance by repeating trial and error work to confirm communication performance while changing parameters in the field It was necessary to determine the location and number of units.

  Even if the network is designed in advance as described above, the change in the communication environment occurs due to structural changes such as new construction or removal of buildings, and movement of objects such as cranes and workers in the plant. It is necessary to optimize the parameters according to. For example, in the method described in Patent Document 1 of the conventional example, the directivity of the antenna is automatically adjusted by using the arrival direction of the received wave and its SINR (signal power to interference noise power ratio) as evaluation values in each radio station. .

Moreover, in the method described in Patent Document 2 of another conventional example, wireless parameter tuning using a radio wave propagation simulator is performed. In this method, propagation in a real environment is simulated by correcting mathematical formulas (such as Okumura curve and 秦 formula) indicating attenuation characteristics used in the simulation, using measured values of radio field intensity at a radio station.
JP 2003-309508 A JP 2005-223732 A

  In the conventional method (Patent Document 1), since the directivity is adjusted so that the SINR of the radio wave received by each radio station is increased, the parameter optimization specialized for the position of the radio station is performed, and the radio in which the entire radio service area is considered. The parameter cannot be optimized. Further, in the conventional method (Patent Document 2), the communication environment can be simulated when the communication environment and the mathematical formula to be applied are known, but should be applied in a situation where the communication environment changes such as a structural change of a surrounding building. Since the formula also changes, this situation cannot be handled. Therefore, the conventional method cannot stably provide desired communication quality to the wireless service area.

  In view of the above-mentioned problems, the present invention estimates the fluctuation path of the propagation path based on the change in the environment in which the radio wave intensity changes due to the movement of people or objects and the structural change of the surrounding building. An object of the present invention is to provide a wireless communication system that realizes a desired communication environment by automatically adjusting to an appropriate wireless parameter according to the result.

  In order to achieve the above object, the first feature of the present invention is as follows. (1) Radio field strength (electric field strength, received power, phase, arrival angle, delay profile, BER (Bit Error Rate), PER ( (2) an estimation device for estimating a radio wave propagation path for each predetermined direction from the measurement value, and (3) a radio parameter suitable for the path. A setting device for deriving (antenna direction, antenna tilt angle, antenna directivity, frequency, transmission output, modulation method, communication method, etc.) and setting the parameters in the radio station; And an output device that outputs the route, and the gist of the invention is a wireless communication system capable of automatically restoring wireless communication by automatically adjusting wireless parameters in accordance with fluctuations in the propagation route.

  In addition, the present invention provides a model creation apparatus that creates a model for radio wave propagation simulation using the position, shape, material, and radio parameters of a radio station in the radio service area, and a ray tracing method from the model. A propagation path estimation device for estimating a radio wave propagation route, an input device for inputting a measurement value of received power of the radio station, and a model correction device for correcting the model from the measurement value A wireless communication system.

  The present invention also includes a display device that displays a propagation path during normal times and when fluctuations occur, the fluctuation factors, and a radio parameter adjustment method according to the fluctuation factors, and supports network management of a radio communication system by a system administrator. It is characterized by this.

  According to the present invention, the propagation path is estimated according to the change in the environment where the radio wave intensity changes due to the movement of a person or an object, or the structural change of the surrounding building, and the radio parameter of the radio station is obtained as a result of the estimation. A desired communication environment can be realized by automatically reconfiguring the wireless communication path by automatically adjusting according to the above.

  Embodiments of the present invention will be described below with reference to the drawings. However, it should be noted that the drawings are schematic.

  FIG. 1 shows the configuration of this embodiment. In the present embodiment, the wireless communication system includes a wireless station 1, a central server 2, and a network 3. One or more wireless stations 1 exist in the wireless communication system, and communication between the wireless stations is performed by wireless communication. Each wireless station 1 communicates with the central server 2 via the network 3.

  A construction example of a wireless communication system is shown in FIG. In this example, four wireless stations 1 (1a, 1b, 1c, 1d) and a central server 2 are arranged in the wireless service area. The outer frame in FIG. 2 is an analysis area 200 for estimating a radio wave propagation path, and the wireless service area is included in the analysis area 200. In the analysis area 200, there are many objects such as buildings and moving objects (workers, cars, cranes, etc.). When operating a wireless communication system, the central server 2 collects measured values of radio field intensity from each wireless station, estimates the cause of fluctuation and the location 201, and appropriately sets the wireless parameters of each wireless station according to the fluctuation. By setting to, the desired communication quality is provided.

  As shown in FIG. 1, the radio station 1 includes a measuring device 11 that measures the radio field intensity of a received radio wave, a radio field intensity storage unit 12 that stores the measured radio field intensity, and a measured radio field intensity and radio field intensity storage unit 12. The radio field intensity comparison unit 13 that compares the stored past measurement values and the wireless parameters (antenna direction, antenna tilt angle, antenna directivity, frequency, transmission output, modulation method, communication method, etc.) notified from the central server 2 ) Is applied to the wireless communication, and the antenna 15 is used for transmission, reception and measurement of the wireless communication.

  The central server 2 includes a radio wave intensity storage unit 12 that stores measurement values transmitted from the wireless station 1, and a communication environment within the area supported by the system (location information of buildings and wireless stations in the area, between each wireless station) A propagation path storage unit 21 that stores a radio wave propagation path), a propagation path estimation unit 22 that estimates a communication environment based on information stored in the radio wave intensity storage unit 12 and the propagation path storage unit 21, and a radio wave intensity storage unit 12 And a radio parameter setting unit 23 for deriving a radio parameter suitable for realizing desired communication quality in the communication environment based on information stored in the propagation path storage unit 21 and notifying the radio station, and a radio wave intensity storage unit 12 Based on the information stored in the propagation path storage unit 21 and the information derived by the wireless parameter setting unit 23, the system administrator is notified of the situation of the communication environment in the area and measures for improving communication. Having a status indicator 24 that indicates.

  In the following, the processing procedure when the radio station is installed and when the system is operated in this embodiment will be described. First, a procedure for installing the wireless station 1 will be described. FIG. 10 shows a flowchart when the radio station is installed. In a first step 9000 in setting up a radio station, a communication environment in an area supported by the system is modeled.

  First, an analysis area 200 supported by the system is set. The set analysis region 200 is an analysis target when the radio wave propagation simulation is performed. As the number of objects to be analyzed increases, the accuracy of simulation improves, but the time and calculation time required for model creation may increase. Usually, an object that more influences radio wave propagation is selected as an analysis target. Next, a three-dimensional coordinate axis (X axis, Y axis, Z axis) is set in the analysis region 200. Next, as a model for radio wave propagation simulation, an object (such as a building) and a radio station are installed in the analysis area 200 in accordance with the set coordinate axis.

  Next, in step 9001, the propagation path of the radio wave transmitted from the radio station is estimated using the radio wave propagation simulation from the position of each object or radio station installed by the above procedure. In step 9002, the estimated propagation Store the route. The ray tracing method is generally used as a method for calculating a propagation path based on environmental conditions such as a building and the ground surface and estimating a received electric field strength, a delay profile, an arrival angle, and the like.

  For example, in the ray launch method, which is one of the ray tracing methods, light rays (rays) are discretely emitted from a transmitter at Δθ in order to search for a propagation path, and a transmitted wave is repeatedly reflected, transmitted, and diffracted by an obstacle. Trace. In this embodiment, the propagation path estimated by the ray tracing method is recorded as a normal path. The installation position and the number of installations of the radio station 1 may be automatically determined by an optimization method such as an experimental design method or a Monte Carlo method using the radio wave intensity estimated by the ray tracing method as an evaluation value.

  Based on the stored propagation path, the radio wave intensity in the path is estimated in step 9003, an appropriate radio parameter for realizing a desired communication quality is determined in step 9004, and derived in steps 9005 and 9006. The wireless station 1 is installed according to the wireless parameters. When it is desired to increase the reception intensity in a specific area, the antenna direction, tilt angle, directivity, and transmission output are adjusted so that radio waves are more radiated in the direction of the propagation path that reaches the area. When a plurality of radio stations 1 exist in the analysis region 200, radio parameters (transmission output adjustment, cell frequency allocation, etc.) are adjusted so as to avoid interference and wasteful power consumption.

  Next, a procedure during operation of the wireless communication system will be described. 11 to 13 show flowcharts during operation. FIG. 11 shows a normal operation flow of the radio station 1. In step 9100, the radio station 1 measures the radio field strength (electric field strength, received power, phase, arrival angle, delay profile, BER, PER, etc.), and stores the measured value and the radio field strength storage unit 12 in step 9101. The radio field intensity comparison unit 13 compares the past measured values, and if the difference is equal to or larger than the threshold value, it is determined that the fluctuation of the radio field intensity has occurred. In step 9104, the measurement value is stored in the radio field intensity storage unit 12. In step 9102, the measurement value is transmitted to the central server 2, and the test signal is transmitted to surrounding radio stations.

  The test transmission signal includes information on the ID of the radio station and radio parameters (antenna direction, antenna tilt angle, antenna directivity, transmission output, modulation method, etc.) applied by the radio station. When parameters used by the wireless station are known, the information may not be included. The threshold value used when the radio wave intensity comparison unit 13 compares the measured value with the past measured value and determines that the fluctuation has occurred, is manually specified or measured a plurality of times, based on the dispersion or standard deviation of the measured value. A threshold value may be calculated.

  FIG. 12 shows a processing flow when a test signal is received. When receiving the test signal, the radio station 1 measures the radio field intensity in Step 9100, stores the measurement value in the radio field intensity storage unit 12 in Step 9104, and in Step 9102, includes information included in the test signal, And the measurement value are associated and transmitted to the central server 2.

  The angle of arrival and its electric field strength are measured by, for example, a method of physically rotating a directional antenna such as a parabolic antenna, and estimating the angle of arrival from a Doppler shift obtained by moving an omnidirectional antenna on a straight line at an equal angle. This method is performed by using an arrival wave estimation algorithm such as a beamformer method or a MUSIC (Multiple Signal Classification) method using an antenna whose directivity can be adjusted, such as an array antenna.

  When transmitting a test signal, the wireless parameter is adjusted to the wireless parameter applied by the wireless station 1 at that time or the wireless parameter for transmitting the test signal. Methods for adjusting the antenna directivity for test signal transmission include non-directional transmission, transmission in a direction in which a change is detected, transmission in a specific direction determined in advance, and the like. When the radio parameter for test signal transmission differs depending on each radio station, the test signal includes information on the parameter for test signal transmission.

  FIG. 13 shows a processing flow when the central server 2 receives measurement value information from the wireless station 1. In step 9104, the central server 2 stores information on the measurement value collected from the radio station 1 in the radio wave intensity storage unit 12, and in step 9101, the difference between the measurement value and the past measurement value is greater than or equal to the threshold value. Make sure. If it is equal to or greater than the threshold value, in step 9105, the simulation model is updated by correcting the position and shape of the object, the material (reflection coefficient, transmission coefficient, etc.), the position of the radio station, and the radio parameters.

  From the model corrected by the above procedure, a propagation path is estimated using the propagation path estimation unit 22 in step 9001, and the path is stored in the propagation path storage unit 21 in step 9002. Next, in step 9003, the central server 2 obtains an estimated value (reception field strength, reception power, phase, arrival angle, delay profile, BER, PER, etc.) of the radio wave environment when the wireless parameter is applied from the route. In step 9106, it is confirmed that the difference between the measured value and the estimated value is equal to or smaller than a threshold value. If the difference is equal to or larger than the threshold value, the model correction is repeated again in step 9105.

  If it is equal to or smaller than the threshold value, in step 9004, an appropriate radio parameter for each radio station is derived using the radio parameter setting unit 23, and the derived radio parameter and the estimated value are notified to each radio station 1. In step 9006, the radio station 1 sets the radio parameter notified from the central server 2 by the radio parameter control unit 14 and stores the estimated value in the radio wave intensity storage unit 12.

  Next, using FIG. 4 to FIG. 6, in step 9105, a procedure for estimating a fluctuation occurrence location and correcting a model based on the measurement value will be briefly described. In the analysis area 200, there are objects (210, 211) and radio stations (220, 221, 222). FIG. 4 shows propagation paths (230 to 234) when the radio stations 220 and 221 transmit test signals to the periphery. A path 230, 231 exists between the radio stations 220 and 221, a path 232, 233 exists between the radio stations 220 and 222, and a path 234 exists between the radio stations 221 and 222.

  Therefore, in the state of FIG. 4, when the wireless station 221 measures the reception power and the arrival direction of the received wave, strong reception power of the test signal from the wireless station 220 is obtained with respect to the incident directions of the paths 230 and 231. When the wireless station 222 performs the same measurement, strong received power from the wireless station 220 is obtained with respect to the incident directions of the paths 232 and 233, and received power from the wireless station 221 is obtained with respect to the incident direction of the path 234.

  FIG. 5 is a propagation path (230 to 235) when the object 212 is newly generated in the analysis region 200. The path 232 is shielded by the object 212, and a new path 235 is formed between the radio stations 221 and 222. A state generated by reflection at the object 212 is shown.

  In this case, when the measurement is performed in the same manner as described above at the wireless station 221, the object 212 is irrelevant to the path between the wireless stations 220 and 221, and thus the received power does not vary. On the other hand, when measured at the wireless station 222, the received power decreases with respect to the incident direction of the path 232, and the received power increases with respect to the incident direction of the path 235. That is, the position of the object that causes reflection or shielding can be estimated from the difference between the measured values in each situation of FIGS.

  FIG. 6 shows a shielding area 240 and a reflection area 241 that can be estimated from the difference between the measured values. The reflection area 240 indicates a range where the reflection surface exists, and the shielding area 241 indicates a range where the shielding object can exist.

  The reflection area 240 is estimated from information such as the positional relationship between the wireless stations 221 and 222, the measurement value at the wireless station 222 (the direction in which the received power of the test signal from the wireless station 221 has increased, and the received power). . Further, it is assumed that the shielded area 241 is on the shielded path 232. In the estimation area (240, 241), the estimation accuracy of the range is improved according to the collected measurement values.

  In the above description, the fluctuation location and factors are estimated from the received power and the arrival direction for the sake of simplicity. However, the estimation accuracy is further improved by adding other measurement information such as a delay profile. For example, assuming that the speed of light is c (m / s), when the delay time of a direct wave from a certain radio station is measured as t1 seconds, the distance d1 from the radio station is obtained by Equation 1, so By combining them, the position of the radio station can be estimated.

Further, when the delay time of the incoming wave reflected once by the wall or the like is measured as t2 seconds, the path length d2 of the reflected wave is obtained by Expression 2. Therefore, since the path difference between the reflected wave and the direct wave is d2−d1, it can be estimated that the reflection point exists on the ellipse 503 represented by Expression 3. However, (x, y) = (0, 0) is the midpoint of the line connecting the transmission antenna and the reception antenna, and the transmission antenna position 501 is (x, y) = (− d1 / 2, 0), the reception antenna. The position 502 is set to (x, y) = (d1 / 2, 0). The reflection point position 504 can be estimated by combining with the measurement result of the reflected wave arrival direction 500 (see FIG. 16).

  If there is a wireless station 1 that does not transmit a measurement value to the central server 2 within a predetermined time despite the test signal being sent, the central server 2 determines that the wireless station is in a state where it cannot communicate, and the step 9105 The model may be corrected.

  In order to derive an appropriate radio parameter, information stored in the propagation path storage unit 21 may be used. For example, the effect of MIMO (Multiple Input Multiple Output), which is one of the communication methods, differs depending on the propagation path. For example, when there is only one propagation path, the effect of MIMO is suppressed.

  In other words, when both radio stations that communicate with each other are sufficiently far away and the angle to see the scattering area is small, the path between radio stations includes a narrow space (such as a tunnel), or the shadow of a building In a propagation environment in which diffracted waves are dominant, there is only one propagation path, and the effect of parallel signal transmission (eigenmode transmission) using SVD (Singular Value Decomposition) cannot be obtained.

  According to the present invention, since the propagation path is estimated by detecting the change of the propagation path, the effectiveness of MIMO in the propagation path can be quantitatively evaluated. Based on this evaluation, it is possible to appropriately select a MIMO algorithm used in the propagation path.

  Based on the radio wave intensity and propagation path in the wireless service area estimated in step 9001 and step 9003 of the above procedure, create a routing table for communication between wireless stations and communication between wireless stations and the central server. Also good. BER, PER, communication speed, etc. that can be provided in each route can be estimated by using the estimated value of the radio wave intensity. Therefore, by using these estimated values as evaluation values for the route, the communication quality and operation of the entire wireless communication system can be estimated. Routing considering efficiency is possible.

  The central server 2 displays the status of the communication environment as needed. FIG. 7 shows an example 100 of display contents. The state display device 24 displays the propagation path 101 and the radio wave intensity (measured value) 102 in the normal state, the propagation path 103 when the fluctuation is detected, and the radio wave intensity (measured value) 104. When the propagation path is displayed (101, 103), the objects (210 to 211) and the radio station existing in the analysis area 200 are also displayed. Further, when fluctuation occurs, the estimated reflection area 240 and shielding area 241 are displayed (103), and the date and time 105 at the time of fluctuation detection is displayed.

  The system administrator checks the displayed propagation path (101, 103), and if the fluctuation occurrence location can be estimated, the interface (106, 300) for manually editing the model (arrangement of objects and radio stations, material designation, etc.) ).

  When displaying the radio wave intensity and the propagation path, the information about the path where the intensity equal to or greater than the threshold is measured among the measurement values measured by the wireless station 1 for each direction of radio wave arrival is displayed (101 to 104). Further, not only the propagation path but also the power distribution in the entire analysis region 200 may be estimated by the radio wave intensity estimating unit 22 and displayed on the state display device 24 (107). In the display part of the propagation path and the radio wave intensity when the fluctuation occurs, the fluctuation occurrence point, the path, and the point where the communication quality is deteriorated are displayed (103, 104, 108).

  The wireless parameter adjustment content 109 derived by the wireless parameter setting unit 23 of the central server 2, the radio wave intensity (estimated value) 110 when the adjustment is performed, the power distribution 111 in the analysis region 200, other than the wireless parameter adjustment Other countermeasures 112 are displayed. Other measures 112 include matters necessary when the desired communication quality cannot be obtained only by adjusting the radio parameters (object movement, material, shape change, installation of a new radio station, etc.), and implementation. Display recommendations for good quality. Further, the status display device 24 may include an input interface (113, 400) for manually adjusting the radio parameters of the radio station 1.

  FIG. 8 shows an operation screen 300 when the system administrator manually performs model correction in step 9105 in the above procedure. On the model correction screen 301, known objects (210, 211), wireless stations (220 to 222), propagation paths (230 to 235), a reflection area 240, and a shielding area 241 are displayed.

  The system administrator newly installs an object or radio station in the model (302), or edits (303) to change parameters (position, shape, material, etc.) of the object or radio station installed on the operation screen 300 Can do. When the model is corrected, if an installation that contradicts the measured value is performed, an error 305 is displayed. For example, the error 305 shows an example in which the system administrator is notified that the position or shape of the object 304 needs to be corrected because the installation of the object 304 blocks the known path 233.

  FIG. 9 shows an operation screen 400 when the system administrator manually adjusts the wireless parameters in step 9004 in the above procedure. The operation screen 400 includes an adjustment item 401 for specifying a wireless station ID to be adjusted and a parameter to be adjusted, an adjustment content 402 for inputting a change value of the parameter specified by the adjustment item, and a change of the adjustment content 402. When applied, radio wave intensity (estimated value) 110 and power distribution 111 are displayed.

  In the above procedure, when the wireless station 1 detects a change in the radio wave environment in Step 9101, the central server 2 treats only the vicinity of the place where the change is estimated to occur as a partial analysis area, and the partial analysis area. The radio wave propagation simulation model correction in step 9105, the propagation path estimation in step 9001, and the radio wave intensity estimation in step 9003 may be performed with the object or the radio station 1 as an analysis target. By setting only a part of the analysis region 200 as an analysis target, the calculation time required for propagation path estimation can be shortened.

  In the above procedure, it is assumed that the positions of all the radio stations are known. However, by detecting the radio stations that are not registered in the system, the radio stations are added where the radio station positions are estimated. The model may be corrected so that

  The location of unregistered radio stations is estimated by receiving radio waves transmitted by the radio stations and using the received power, direction of arrival, delay profile, and information on surrounding building structures. It becomes possible. As a method using received power, for example, the probability that an unregistered radio station exists at each point in the estimation range is calculated from the received power value obtained by measurement and the propagation model, and the point with the highest likelihood is calculated. Estimated position. FIG. 15 shows an example in which the position of an unregistered radio station is estimated based on the arrival direction of radio waves from the unregistered radio station. According to this method, even when a radio station moves, in step 9105, model correction can be performed by estimating the position of the radio station in accordance with the movement.

  In the above procedure, the fluctuation of the surrounding environment is estimated by using the test signal, but the fluctuation may be estimated by using the radio wave intensity of the radio wave in normal communication. When the central server 2 adjusts the radio parameters of each radio station, since the central server 2 knows the radio parameter information included in the test signal, the same processing as the above procedure is performed even if it is not a test signal Is possible. When the wireless station autonomously adjusts the wireless parameter, or when there is a wireless station that is not registered in the system, the wireless parameter applied by the wireless station that transmitted the signal may be unknown. In this case, countermeasures can be taken by urging the wireless station to notify the surroundings of the applied wireless parameter, or by estimating the wireless parameter of the wireless station from the propagation path and received power.

  In the above procedure, it is assumed that the performance of each radio station and the communication service to be provided are the same, but the performance of each radio station (type of adjustable radio parameters, calculation processing speed, power consumption, etc.), the mobility of the radio station Evaluation values in the wireless parameter setting unit 23 for performance (fixed position, movable), remaining battery capacity of the wireless station, wireless service content provided by the wireless station (for general communication, emergency communication, etc.), communication amount, and communication frequency The wireless parameter may be adjusted in step 9004.

  For example, when the content of a wireless service is used as an evaluation value, the performance required for communication differs for general communication and emergency communication. Because emergency communication requires higher levels of communication interruption and delay prevention than general communication, it is necessary to adjust radio parameters so that propagation paths in various directions can be made to cope with possible fluctuations. . By setting a weight for each evaluation value, it is possible to adjust the radio parameters in detail.

  FIG. 3 shows the configuration of the wireless station 4 in the second embodiment of the present invention. In the first embodiment, the central server 2 estimates the propagation path. However, the wireless station includes the propagation path estimation unit 22, and one or more wireless stations receive radio field intensity measurements and wireless parameters from the surrounding wireless stations. In step 9105, the radio wave propagation path may be estimated in step 9105, the radio wave propagation path may be estimated, and in step 9006, each radio station may autonomously adjust radio parameters.

  The wireless station 4 includes a measuring instrument 11 that measures the radio field intensity of the received radio wave, a radio field intensity storage unit 12 that stores the measured radio field intensity, and a past measurement stored in the measured radio field intensity and radio field intensity storage unit 12. A radio wave intensity comparison unit 13 that compares values, and a propagation path storage unit 21 that stores a communication environment in the area supported by the system (location information of buildings and radio stations in the area, radio wave propagation paths between radio stations, and the like). A propagation path estimation unit 22 that estimates a communication environment based on information stored in the radio wave intensity storage unit 12 and the propagation path storage unit 21, and information stored in the radio wave intensity storage unit 12 and the propagation path storage unit 21 In order to achieve desired communication quality in the communication environment, an appropriate radio parameter is derived and notified to other radio stations, and a radio parameter (ante) derived by the radio parameter setting unit 23 is derived. Direction, antenna tilt angle, antenna directivity, frequency, transmission output, modulation method, communication method, etc.) and a wireless parameter control unit 14 for wireless communication, and an antenna 15 used for wireless communication transmission, reception, and measurement. And have.

  FIG. 14 shows a flowchart at the time of operation in the second embodiment. The operation procedure of the present embodiment is the same as that of the first embodiment. However, steps 9104, 9101, 9105, 9001 to 9004, and 9106 of the procedure performed by the central server 2 in the first embodiment are performed by the wireless station 4.

  The wireless station 1 in the first embodiment, the wireless station 4 in the second embodiment, and the central server 2 may be mixed in the wireless communication system. When the central server 2 is used, the measurement value stored in the radio wave intensity storage unit 12 of the wireless station 4 in step 9104, the change contents at the time of model correction in step 9105, the path information stored in the propagation path storage unit 21 in step 9002, The central server 2 is notified of the estimated radio field intensity at 9003 and the wireless parameter information derived by the wireless parameter setting unit 23 at step 9004. The central server 2 reconfigures the model based on the information collected from the wireless station 4b and notifies the wireless station of appropriate wireless parameters.

  Since the radio station 4 has the propagation path estimation unit 22, an autonomous distributed radio communication system that does not use a central server can be configured. Even when the central server 2 is used, the wireless parameters of each wireless station are appropriately set by the wireless parameter setting unit 23 held by the wireless station 4 even if the wireless station 4 is introduced and the wireless server 4 cannot communicate with the central server 2. it can. According to the present embodiment, since the wireless station 4 can play the role of the central server 2, the fault tolerance of the system is improved. Further, by performing processing in a relatively narrow area, the number of objects to be considered in the simulation is reduced, so that it is possible to reduce the amount of calculation necessary for estimating the propagation path.

In each of the above embodiments, it is assumed that in step 9101, the occurrence of fluctuations in the communication environment is detected from the radio field intensity of the radio wave transmitted from each radio station. Measurement, acquisition of position information by GPS receivers (Global Positioning System) held by objects and radio stations, position estimation by radio wave intensity transmitted by radio stations installed on each object, and detection based on a combination of techniques You can go.

  For example, in the image recognition method, the position, shape, and type of an object are detected based on the image information of the object captured by the camera. By detecting an object by image recognition using a surveillance camera installed in the plant and correcting the model based on the detected information, it is possible to derive an appropriate wireless parameter corresponding to the fluctuation in step 9004 It is. For example, the status display device 25 displays the reflection area 240 and the shielding area 241 estimated from the radio wave intensity (100), but if a camera that captures the object 212 is installed, the range of the area is estimated in more detail. The estimation accuracy of the propagation path is improved.

  If the material of the object cannot be recognized from the image, it is difficult to estimate the influence of the object on the radio wave, but the estimation accuracy can be improved by combining with the measured value of the radio wave intensity. For example, when the object 212 is a substance that almost transmits radio waves, the model correction is performed in consideration of reflection by the object 212 only by image information, but it is measured that the reflection and shielding by the object 212 can be ignored by measuring the radio wave intensity. Therefore, it is possible to perform model correction in step 9105 in consideration of the material of the object.

  The present invention provides a system for autonomously controlling a wireless environment by linking a radio wave propagation simulator and a radio in a plant instrumented radio system and a radio train control system (CBTC: Communication Based Train Control). Applicable to.

FIG. 1 is a diagram illustrating a configuration of a wireless communication system according to a first embodiment of the present invention. FIG. 2 is a diagram showing an example of a wireless system configuration of the present invention. FIG. 3 is a diagram illustrating a configuration of a radio station according to the second embodiment of the present invention. FIG. 4 is a diagram illustrating an example of a radio wave propagation path. FIG. 5 is a diagram showing an example of a propagation path when fluctuation occurs in the situation of FIG. FIG. 6 is a diagram illustrating an example of a variation portion estimated from a difference between measured values in the situation of FIGS. 4 and 5. FIG. 7 is a diagram showing an example of contents displayed on the display device of the present invention. FIG. 8 is a diagram illustrating an operation screen for manual model correction according to the first embodiment of the present invention. FIG. 9 is a diagram showing an operation screen for manual wireless parameter adjustment in the first embodiment of the present invention. FIG. 10 is a diagram illustrating a processing flow (when a wireless station is installed) of the wireless communication system according to the first embodiment of the present invention. FIG. 11 is a diagram showing a processing flow (normal operation of the radio station during operation) of the radio communication system according to the first embodiment of the present invention. FIG. 12 is a diagram illustrating a processing flow of the wireless communication system according to the first embodiment of the present invention (operation when receiving a test signal of a wireless station during operation). FIG. 13 is a diagram showing a processing flow of the wireless communication system according to the first embodiment of the present invention (operation when the central server receives measurement values during operation). FIG. 14 is a diagram illustrating a processing flow of the wireless communication system according to the second embodiment of the present invention (operation when receiving a test signal of a wireless station during operation). FIG. 15 is a diagram illustrating an example of estimating the position of an unregistered radio station. FIG. 16 is a diagram showing a method for estimating the position of a reflection point using the arrival direction and delay time of an incoming wave in the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Radio station 2 Central server 3 Network 11 Measuring instrument 12 Radio wave intensity storage part 13 Radio wave intensity comparison part 14 Wireless parameter control part 21 Propagation path storage part 22 Propagation path estimation part 23 Wireless parameter setting part 24 Status display apparatus 100 Status display screen 101 Normal propagation path 102 Radio wave intensity (measured value)
103 Propagation path when detecting change 104 Radio wave intensity (measured value)
105 Date and time of change detection 106 Model edit 107 Power distribution display 108 Fluctuation path / quality degradation point 109 Adjustment content 110 Radio wave intensity (estimated value)
111 Power Distribution 112 Other Countermeasures 113 Manual Adjustment 200 Analysis Area 210, 211 Object 220-222 Radio Station 230-235 Propagation Path 240 Reflection Area 241 Blocking Area 300 Model Correction Operation Screen 301 Screen 302 New Installation 303 Editing 304 Object 305 Error 400 Wireless Parameter operation screen 401 Adjustment item 402 Adjustment content 500 Direction of reflected wave arrival 501 Transmitting antenna position 502 Reception antenna position 503 Ellipse 504 Reflection point estimation position 9000 Model creation procedure 9001 Propagation path estimation procedure 9002 Radio wave intensity estimation procedure 9003 Radio wave intensity estimation procedure 9004 Wireless Parameter derivation procedure 9005 Radio station installation procedure 9006 Radio parameter setting procedure 9100 Radio wave intensity measurement procedure 9101 Radio wave intensity comparison procedure 9102 Strike signal transmission procedure 9103 test signal receiving procedure 9104 RSSI storage procedure 9105 model correction procedure

Claims (8)

  In a wireless communication system including a plurality of wireless stations that perform wireless communication and a central server that manages the wireless station, the wireless station includes a measuring device that measures radio wave intensity in the wireless service area, The server includes a radio wave intensity storage unit for storing the measurement value, a propagation path estimation unit for estimating a radio wave propagation path for each predetermined direction from the measurement value, and a wireless station radio depending on the state of the propagation path A radio parameter setting unit that sets at least one parameter of a radio station position, antenna direction, antenna tilt angle, antenna directivity, frequency, transmission output, modulation scheme, and communication scheme as parameters in the radio station, and the radio wave intensity storage unit And a status display device that displays information stored in the propagation path storage unit and a processing result by the wireless parameter control unit. Stem.   In a wireless communication system including a plurality of wireless stations that perform wireless communication, the wireless station includes a measuring device that measures the radio field intensity in the radio service area, and a radio field intensity storage unit that stores the measurement value. , A propagation path estimation unit for estimating a radio wave propagation path for each predetermined direction from the measured value, and a wireless station position, antenna direction, antenna tilt angle, antenna directivity as wireless parameters of the wireless station according to the state of the propagation path A radio parameter setting unit that sets at least one parameter of frequency, transmission output, modulation scheme, and communication scheme in the radio station.   The radio communication system according to claim 1 or 2, wherein the propagation path estimation unit uses a position, shape, material, and radio parameter of a radio station of a building in the radio service area for radio wave propagation simulation. And a radio wave propagation path is estimated from the model using a ray tracing method.   The radio communication system according to any one of claims 1 to 3, wherein the radio station stores a radio wave intensity storage unit for storing the measurement value, and the radio wave intensity every time the measurement value is obtained. A radio field intensity comparison unit that compares a past measurement value stored in the storage unit and determines that a change has occurred in the communication environment when the difference is equal to or greater than a set threshold value. Wireless communication system.   4. The wireless communication system according to claim 3, wherein the display device has an interface that allows a system administrator to manually create and correct a simulation model according to the change.   6. The wireless communication system according to claim 1, 3, 4 or 5, wherein the display device is desired only by adjusting a wireless parameter when a change in a communication environment is detected. A wireless communication system characterized by displaying the movement, material, shape change, and installation of a new wireless station in a wireless service area, which is a measure other than wireless parameter adjustment, when the communication quality of the wireless communication is not obtained.   The wireless communication system according to claim 1, claim 3, claim 4, claim 5 or claim 6, wherein the display device is wirelessly manually set by a system administrator in accordance with the change. A wireless communication system comprising an interface capable of adjusting parameters.   In the wireless communication system according to claim 1, claim 3, claim 4, claim 5, claim 6 or claim 7, further, video acquisition for acquiring video in a wireless service area The wireless station or the central server has a video storage unit that stores video data acquired by the video acquisition device, the video data, and feature quantities of past video data stored in the video storage unit And a video comparison unit that determines that a change has occurred in the communication environment when the difference is equal to or greater than a set threshold value.

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