JP2009044643A - Call-quality estimating system and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a call-quality estimating system and method which estimates the call-quality of a VoIP call, based on the arrangement of access-points and client-terminals of a wireless LAN. <P>SOLUTION: The call-quality estimating system has an information input portion 10 for inputting the arrangement of access-points and client terminals, an interference-AP specifying portion 33 for specifying interference-access-points relative to object-access-points, an interference-terminal specifying portion 35 for specifying interference-client-terminals, an interference-connection-terminal counting portion 37 for counting the number of client-terminals belonging to either one of interference-access-points, and an available-terminal-deriving portion 41 for deriving the maximum number of available-client-terminals belonging to the object-access-points, based on the obtained information. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a call quality estimation system and a call quality estimation method for estimating call quality of a VoIP call performed using a plurality of access points and a plurality of client terminals in a wireless LAN.

As a conventional wireless LAN design method, for example, the one described in Patent Document 1 is known. In this design method, an optimal access point and client arrangement are determined in consideration of the response and radio wave interference in the client. In general, access point placement in a wireless LAN design is designed such that the reception level from each access point is a certain level or more in a certain area, and the same frequency channel (or interference) The access points using the frequency channel are arranged at a certain distance from each other.
JP 2004-304255 A Japanese Patent No. 3439396 Japanese Patent Laid-Open No. 62-173835

  However, in communications that allow delay, such as data communications, communications that are satisfactory to some extent are possible even with a wireless LAN designed based on the above concept, but in communications that require real-time performance, such as VoIP communications. In addition, deterioration of call quality and disconnection of the call are likely to occur due to packet loss caused by radio wave interference between devices. Therefore, if the system is designed by the conventional method, the number of client terminals to be accommodated will be overestimated. If voice communication clients close to the designed maximum number are introduced into an actual system, the call quality may be degraded. Communication interruption may occur. Therefore, in a wireless LAN in which VoIP calls are used, it is necessary to arrange devices while considering call quality, and it is desired that such call quality can be simulated at the design stage of the wireless LAN.

  Accordingly, an object of the present invention is to provide a call quality estimation system and a call quality estimation method that can estimate the call quality of a VoIP call from the arrangement of wireless LAN access points and client terminals.

  The call quality estimation system of the present invention is a call quality estimation system that estimates call quality of a VoIP call that is performed using a plurality of access points and a plurality of client terminals of a wireless LAN, the access point arrangement, and Based on the information input means for inputting the number of client terminals, and the arrangement and the number of pieces input by the information input means, it is estimated that the interference source causes radio wave interference to a predetermined target access point among a plurality of access points. Interference source AP identifying means for identifying the interference source access point to be detected from other access points, and an interference source that causes radio wave interference to the target access point based on the arrangement and number of units input by the information input means Interfering client terminals that are estimated to be Interference source terminal specifying means to be determined, and terminal counting means for counting the number of client terminals belonging to the interference source access point specified by the interference source AP specifying means based on the arrangement and the number of units input by the information input means Based on the number of interference source access points identified by the interference source AP identification means, the number of interference source client terminals identified by the interference source terminal identification means, and the number of client terminals counted by the terminal counting means, And a callable number deriving unit for deriving the maximum number of client terminals that can call and belong to the target access point.

  In this call quality estimation system, first, the arrangement of each access point and each client terminal is input. Based on the input arrangement, an interference source access point and an interference source client terminal that are estimated to be radio wave interference sources are identified for the target access point. Further, the number of client terminals belonging to the interference source access point is counted. Based on this information, it reflects the influence of interference with other access points, the influence of interference with client terminals, and the influence of client terminals belonging to the interference source access point. The maximum number of client terminals that can make a call is derived. Therefore, this maximum number and the number of client terminals that are actually expected to belong to the target access point can be compared, and call quality can be estimated.

  In this case, the means for deriving the number of callable units is capable of making calls by belonging to the target access point and the number of interference source access points, the number of interference source client terminals, and the number of all client terminals belonging to the interference source access point. The maximum number of client terminals that can make a call may be obtained based on a reference table that stores the maximum number of client terminals in association with each other in advance.

  Further, the interference source AP identifying means uses the same frequency channel as that of the target access point, and transmits an access point that transmits a radio wave whose intensity received by the target access point is equal to or higher than a predetermined value, as an interference source of the target access point. It may be specified as an access point.

  Further, the interference source terminal identifying means uses the same frequency channel as that of the target access point and transmits a radio wave whose intensity received at the target access point is equal to or higher than a predetermined value to the client terminal that is the interference source of the target access point. It may be specified as a client terminal.

  The call quality estimation method of the present invention is a call quality estimation method for estimating the call quality of a VoIP call performed using a plurality of access points and a plurality of client terminals of a wireless LAN, comprising: arrangement of access points; and Based on the information input step for inputting the number of client terminals and the arrangement and the number of units input in the information input step, it is estimated that the interference source causes radio wave interference to a predetermined target access point among a plurality of access points. The interference source AP that identifies the interference source access point to be detected from other access points, and the interference source that causes radio wave interference to the target access point based on the arrangement and number of units input by the information input step Interfering client terminals that are estimated to have multiple client terminals A terminal count for counting the number of client terminals belonging to the interference source access point identified in the interference source AP identification step, based on the interference source terminal identification step identified from the inside and the arrangement and number of units input in the information input step Step, the number of interference source access points identified in the interference source AP identification step, the number of interference source client terminals identified in the interference source terminal identification step, and the number of client terminals counted in the terminal counting step And a step of deriving the number of callable units for deriving the maximum number of client terminals that can call and belong to the target access point.

  In this call quality estimation method, first, the arrangement of each access point and each client terminal is input. Based on the input arrangement, an interference source access point and an interference source client terminal that are estimated to be radio wave interference sources are identified for the target access point. Further, the number of client terminals belonging to the interference source access point is counted. Based on this information, it reflects the influence of interference with other access points, the influence of interference with client terminals, and the influence of client terminals belonging to the interference source access point. The maximum number of client terminals that can make a call is derived. Therefore, this maximum number and the number of client terminals that are actually expected to belong to the target access point can be compared, and call quality can be estimated.

  According to the call quality estimation system and the call quality estimation method of the present invention, it is possible to estimate the call quality of a VoIP call from the arrangement of wireless LAN access points and client terminals.

  Hereinafter, a preferred embodiment of a call quality estimation system according to the present invention will be described in detail with reference to the drawings.

  A call quality estimation system 1 shown in FIG. 1 is a system for simulating the call quality of a VoIP call prior to designing a wireless LAN facility when a VoIP call extension system using a wireless LAN is to be built in a building. . As shown in FIG. 2, in such a VoIP call extension system 200, while belonging to a plurality of wireless LAN access points AP1 to APm arranged in the building and the access points in the building, A plurality of client terminals T1 to Tn connected to the wireless LAN are used.

  As shown in FIG. 1 again, the call quality estimation system 1 includes an information input unit 10 for inputting information necessary for simulation from the outside, and a calculation unit 30 for calculating call quality estimated based on the input information. And an information output unit 50 that outputs the result of the simulation obtained by the calculation to the outside.

  The information input unit 10 includes a building design drawing input unit 11, an access point information input unit 13, a client terminal information input unit 15, and a device setting parameter information input unit 17. Functions and operations of the above-described units of the information input unit 10 will be described later. The calculation unit 30 is a terminal arrangement unit 31 during a call that performs each calculation based on each information input from the outside by the information input unit 10, an interference source AP identification unit 33, an interference source terminal identification unit 35, and an interference connection terminal counting unit. 37, and a callable number deriving unit 41. The functions and operations of the above units of the calculation unit 30 will be described later.

  Here, the physical configuration of the call quality estimation system 1 will be described with reference to FIG. As shown in FIG. 3, the call quality estimation system 1 physically includes a CPU 101, a RAM 102 and a ROM 103 which are main storage devices, an auxiliary storage device 105 such as a hard disk, and an input device 106 such as a keyboard and a mouse which are input devices. The computer system includes an output device 107 such as a display and a printer, and a communication module 104 which is a data transmission / reception device such as a network card. The information input unit 10, the calculation unit 30, the information output unit 50, and the function units 11 to 17, 31 to 41, and the like illustrated in FIG. 1 have predetermined computer software on hardware such as the CPU 101 and the RAM 102 illustrated in FIG. 2. By reading, the communication module 104, the input device 106, and the output device 107 are operated under the control of the CPU 101, and data is read and written in the RAM 102 and the auxiliary storage device 105.

  Hereinafter, the function of each element of the call quality estimation system 1 will be described with reference to FIG. 1 again.

  The building design drawing input unit 11 of the information input unit 10 inputs a design drawing of a building for which a VoIP call extension system is to be constructed, using CAD (Computer Aided Design). The access point information input unit 13 inputs the installation position of the wireless LAN access point in the building on the building design drawing. The client terminal information input unit 15 inputs an area A in which a client terminal used in the VoIP call extension system can exist (hereinafter referred to as “terminal existing area”) A on the building design drawing and exists in this terminal existing area. Input information on the number of client terminals to be used. Further, the device setting parameter information input unit 17 inputs various parameters for device setting such as device names of access points and client terminals.

  The busy terminal arrangement unit 31 of the computing unit 30 estimates the number of client terminals that are in a call at a certain moment (hereinafter referred to as “busy client terminals”) among the input number of client terminals. Assume that this client terminal is placed during a call. The interference source AP identification unit 33 identifies other access points (hereinafter referred to as “interference source access points”) that are expected to generate radio wave interference with the access points input by the information input unit 10. To do. The interference source terminal specifying unit 35 specifies a client terminal during a call (hereinafter referred to as “interference source terminal”) that is expected to cause radio wave interference with itself for each access point input by the information input unit 10. . The interference connection terminal counting unit 37 identifies the total number of client terminals (hereinafter, referred to as “interference connection terminals”) that are in a call belonging to any of the interference source access points. The information output unit 50 outputs information about the call quality for each access point estimated by the calculation unit 30 to the outside by display display or printout.

  Next, the call quality estimation process performed by the call quality estimation system 1 will be described in detail with reference to FIGS. 1 and 4. This call quality estimation process is performed by the cooperation of the information input unit 10, the calculation unit 30, and the information output unit 50 described above.

  First, the information input unit 10 of the call quality estimation system 1 allows the user to input information necessary for call quality estimation. First, the building design drawing input unit 11 inputs a building design drawing of a building for which a VoIP extension system is to be constructed by CAD (Computer Aided Design) (S401 in FIG. 4), and as shown in FIG. To display. Subsequently, the access point information input unit 13 inputs the arrangement of the wireless LAN access points installed in the building on the building design drawing (S402).

  Next, the client terminal information input unit 15 inputs the terminal presence area A on the building design drawing, and further inputs the number of client terminals scheduled to be used in the terminal presence area (S403). Next, the device setting parameter information input unit 17 inputs device names of the access point and client terminal and various setting parameters (S404). Examples of setting parameters to be input here include settings related to wireless LAN such as wireless LAN standards, usage channels, power save, and wireless transmission speed, settings related to VoIP such as codec type and packet transmission interval, access points, and client terminals. There are settings related to unique functions. As this setting parameter, it is preferable to select a parameter that affects the call quality of the VoIP call extension system 200.

  Through the input process as described above, a screen as shown in FIG. 5 is displayed on the display 107 of the system 1. In the example of this screen, there are two access points and 20 client terminals in the terminal presence area.

  Subsequently, the terminal arrangement unit 31 during a call of the calculation unit 30 estimates the number of client terminals during a call based on the above input information, and assumes the arrangement of these client terminals during a call. (S405) As described above, the following method can be considered as an example of a method for assuming the number and arrangement of client terminals during a call. In other words, the ratio of client terminals that are in a call among all client terminals is input from the outside, and the number of client terminals in a call is estimated by the product of the number of all client terminals and the input “presence ratio”. can do. Further, the assumption of the arrangement of the client terminals during a call can be made by dividing the terminal presence area A into a plurality of cells and randomly arranging the client terminals during a call so as to be uniformly distributed in the divided cells. . In the terminal presence area A, when the probability that a client terminal in a call is located is different for each cell, the existence probability of the client terminal in a call for each cell is input, and the arrangement of client terminals in a call is more strictly set. Assumptions may be made.

  Next, the interference source AP specifying unit 33 calculates an RSSI (Received Signal Strength Indicator) in a case where a radio wave transmitted by a certain access point is received by another access point in all combinations at each of the access points AP1 to APm ( S406). For example, when there are m access points, the output calculation result is represented by an m × m matrix as shown in FIG. Note that “<APa−APb>” shown in the table of FIG. 6 represents RSSI when the radio wave transmitted by the ath access point APa is received by the bth access point APb. In order to execute the processing of S406, software for calculating RSSI when the radio wave transmitted by the access point is received by another access point may be incorporated in the interference source AP specifying unit 33, or the interference source AP The identification unit 33 may perform processing in cooperation with commercially available radio LAN radio wave propagation simulation software.

  Next, the interference source terminal specifying unit 35 calculates the RSSI when the client terminal during a call receives a radio wave transmitted by the access point for all combinations of each access point and each client terminal during a call (S407). For example, when there are m access points and n client terminals in a call, the output calculation result is represented by an m × n matrix as shown in FIG. Note that <APa-Tb> shown in the table of FIG. 7 represents an RSSI when a radio wave transmitted by the a-th access point APa is received by the b-th talking client terminal Tb. Similarly to S406 described above, in order to execute the process of S407, software for calculating RSSI when the radio wave transmitted by the access point is received by the client terminal during a call is incorporated in the interference source terminal specifying unit 35. Alternatively, the interference source terminal identifying unit 35 may perform processing in cooperation with commercially available radio LAN radio wave propagation simulation software.

  Subsequently, the interference source AP identification unit 33 uses the RSSI (FIG. 7) calculated in S407 to estimate the access point to which the busy client terminal belongs. (Step S408) Here, it is assumed that the client terminal during a call belongs to the access point having the largest RSSI among the radio waves received from the access points AP1 to APm. And the access point name to which it belongs and its RSSI are extracted for each client terminal during a call. In addition, the channel used by each client terminal during a call is also extracted based on the channel used by the access point to which each client terminal during a call belongs.

  For example, in the case of the client terminal T1 described in FIG. 7, in the RSSI (<AP1-T1>, <AP2-T1>,..., <APm-T1>) indicated in the row of the client terminal T1. The cell having the maximum value is selected, and the access point name and RSSI in the cell are extracted. Further, the use channel of the access point is used as the use channel of the client terminal. When the above processing is performed in all the client terminals, as illustrated in FIG. 8, an output result indicating the access point and the channel used can be obtained for each client terminal during a call.

  Further, the interference source AP specifying unit 33 uses the output result of FIG. 8 to calculate the number of client terminals in a call belonging to each of the access points AP1 to APm. An example of the output result is shown in FIG. Subsequently, the wireless transmission rate used in the communication between the access point and the client terminal is estimated from the RSSI (FIG. 8) calculated in step S408 (step S409). Here, a transmission rate table as shown in FIG. 10 is used, and the radio transmission rate of each communication is estimated in accordance with the criteria set in the transmission rate table. An example of the output result of the process of S409 is shown in FIG.

Note that a, b, m, n, o, p, y, and z shown in FIG. 10 are constants, and the relationship between them is a>b>m> n and o>p>y> z. Further, the relationship between RSSI and wireless transmission speed in FIG. 10 is as follows.
When the RSSI is a or higher, the transmission rate is o [Mbps].
-When RSSI is less than a and greater than or equal to b, the transmission rate is p [Mbps].
-If RSSI is less than m and greater than or equal to n, the transmission rate is z [Mbps].
・ If RSSI is less than n, the client terminal cannot communicate.

  Subsequently, the interference source AP specifying unit 33 specifies an interference source access point for each access point (target access point) using FIG. 6 (step S410). Here, the criteria for estimating the interference source access point are as follows. That is, an access point that uses the same frequency channel as the target access point, and that is an access point that transmits radio waves such that the RSSI received at the target access point is equal to or greater than a preset value. Is estimated to be the interference source access point for the target access point.

  For example, the access point uses one channel that is the same channel as the access point AP1, and {<AP1-AP1>, <AP2-AP1>, <AP3-AP1>,. . . , <APm-AP1>}, an access point that transmits a radio wave whose RSSI received at the access point 1 is equal to or larger than a set value (RSSI_Interference_AP) is estimated as an interference access point for the access point AP1. Through the above procedure, the interference source AP identification unit 33 identifies the interference source access point for all the access points AP1 to APm.

  Further, the interference connection terminal counting unit 37 calculates the total number of interference source access points for each access point and the total number of client terminals (interference connection terminals) in communication belonging to the interference source access point. Output to the access point. In addition, the minimum value of the radio transmission rate used by the interference connection terminal is output in association with each access point. An example of the output result of this processing is shown in FIG.

  Subsequently, the interference source terminal specifying unit 35 specifies the interference source terminal for each access point (target access point) using FIG. 7 (step S411). Here, the criteria for estimating the interference source terminal are as follows. That is, a client terminal that is in a call using the same frequency channel as the target access point and that is a client terminal that receives a radio wave transmitted by the target access point with an RSSI equal to or higher than a preset setting value. It is estimated that it is an interference source terminal for the target access point.

  For example, the target access point from which the client terminal T1 is estimated as an interference source terminal is an access point that uses the same frequency channel as the client terminal T1, and {<AP1-T1>, <AP2-T1>, <AP3- T1>,. . . , <APm-T1>} is an access point that transmits a radio wave whose RSSI received by the client terminal T1 is equal to or greater than a set value (RSSI_Interference_terminal). Through the above procedure, the interference source terminal identification unit 35 identifies the interference source terminal for all the access points AP1 to APm. Further, the total number of interference source terminals and the minimum value of the wireless transmission rate used by the interference source terminals are output in association with the respective access points. An example of these output results is shown in FIG.

  Finally, the callable number derivation unit 41 estimates the call quality of the radio area formed by each access point AP1 to APm based on the identified interference source access point and interference source terminal (S412). In the process of S412, a QoS conversion table 51 as shown in FIG. 14 is used. This QoS conversion table 51 is capable of making VoIP calls belonging to the target access point using the number of interference source access points corresponding to the target access point, the number of interference source terminals, and the number of interference connection terminals as parameters. The maximum number of client terminals is shown. In other words, the numerical value written in the cell specified by the above three parameters in this table indicates that the call is under control of the target access point when the target access point receives interference as specified by the above three parameters. The number of possible client terminals (Maximum Access Number) is shown.

  In the computing unit 30, such a QoS conversion table is used to set the information input in the process of S404 described above (setting parameters that affect the call quality of the VoIP extension system, such as device names and setting parameters of access points and client terminals). ) Or those that can handle all the operating environments specified by the wireless transmission speed estimated in S409 are calculated and prepared in advance. Then, the QoS conversion table employed in S412 is selected based on the wireless transmission rate estimated in S409 and the setting parameters affecting the call quality of the VoIP extension system input in S404. In addition, when it is difficult to create the QoS conversion table by calculation, it is also possible to create it by estimation from some actual measurement data.

  After that, for each target access point, referring to the QoS Conversion Table 51 based on the three parameters of the number of interference source access points, the number of interference source terminals, and the number of interference connection terminals, the Maximum Access Table 51 is referred to. Derive Number. Next, the derived Maximum Access Number is compared with the number of client terminals in communication (see FIG. 9) belonging to the target access point.

  When the number of client terminals in a call is equal to or less than the Maximum Access Number, it is determined that the call quality of the client terminal located in the wireless area formed by the target access point is good, and in other cases, It is determined that the call quality is deteriorated, and the determination result is output. An example of the output result of the process of S412 is shown in FIG. The output result as shown in FIG. 15 may be displayed on a display or printed out.

  With the processing of the call quality estimation system 1 described above, considering the interference between wireless LAN devices such as an access point and a client terminal when placed in a building, the call quality by the client terminal in the wireless area formed by each access point Can be simulated in advance.

  As a result of such simulation, if the call quality is expected to deteriorate, the above process is performed by reducing the number of client terminals arranged in the terminal presence area A or changing the arrangement of access points. By repeating, it is sufficient to determine the access point arrangement and the maximum number of client terminals that can ensure a certain quality. As described above, since the call quality in the VoIP extension system can be detected in advance by using the call quality estimation system 1, it is possible to easily construct a VoIP extension system that guarantees the call quality. Time and cost can be reduced.

  In addition, according to the call quality estimation system 1, it is possible to design a VoIP extension system that guarantees call quality that is impossible with other wireless LAN estimation methods. If the conventional design method assuming wireless LAN data communication is applied to VoIP communication as it is, especially in office use that covers multiple floors, excessive wireless access points are installed and transmission power is further increased. In addition to increasing costs, it often caused problems such as voice interruptions. On the other hand, in a design focused on voice communication such as the design using the call quality estimation system 1, rather, the number of wireless access points is reduced and consequently the number of accommodated client terminals is increased. Even if it is as it is, it is possible to secure the number of accommodated client terminals more than before by refining the access point by narrowing the transmission output.

It is a functional block diagram which shows one Embodiment of the call quality estimation system which concerns on this invention. It is a functional block diagram which shows an example of the VoIP call extension system by which the call quality estimation system which concerns on this invention is utilized and designed. It is a block diagram which shows the hardware constitutions of the telephone call quality estimation system of FIG. It is a flowchart which shows the call quality estimation process by the call quality estimation system of FIG. It is a figure which shows an example of the input screen displayed in the process of a call quality estimation system. It is an example of the table | surface which shows RSSI between each access point. It is a table | surface produced | generated in the process of a telephone call quality estimation system, and is an example of the table | surface which shows RSSI between each access point and each client terminal during a telephone call. It is a table | surface produced | generated in the process of a call quality estimation system, and is an example of the table | surface which shows the attribution access point etc. of each client terminal during a call. It is a table | surface produced | generated in the process of a telephone call quality estimation system, and is an example of the table | surface which shows the number etc. of the client terminal in a call to which each access point belongs. It is a table | surface utilized in the process of a telephone call quality estimation system, and is an example of the table | surface which matches RSSI and a wireless transmission rate. It is a table | surface produced | generated in the process of a call quality estimation system, and is an example of the table | surface which shows the attribution access point etc. of each client terminal during a call. It is a table | surface produced | generated in the process of a call quality estimation system, and is an example of the table | surface which shows the interference source access point etc. of each access point. It is a table | surface produced | generated in the process of a telephone call quality estimation system, and is an example of the table | surface which shows the interference source terminal etc. of each access point. It is a table | surface utilized in the process of a call quality estimation system, and is an example of QoS Conversion Table which links | relates three parameters and Maximum Access Number. It is a table | surface output in the process of a call quality estimation system, and is an example of the table | surface which shows Maximum Access Number, call quality, etc. of each access point.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Call quality estimation system, 10 ... Information input part (information input means), 13 ... Access point information input part, 15 ... Client terminal information input part, 33 ... Interference source AP specification part (interference source AP specification means), 35 ... Interference source terminal specifying part (interference source terminal specifying means), 37 ... Interference connection terminal counting part (terminal counting means), 41 ... Callable number deriving part (callable number deriving means), 51 ... QoS Conversion Table (reference table) ), A ... terminal presence area, AP1-APm ... access point, T1-Tn ... client terminal.

Claims (5)

A call quality estimation system for estimating call quality of a VoIP call performed using a plurality of access points and a plurality of client terminals of a wireless LAN,
Information input means for inputting the arrangement of the access points and the number of the client terminals;
Based on the arrangement and the number of units input by the information input means, interference source access points estimated to be interference sources that cause radio wave interference to a predetermined target access point among the plurality of access points, Interference source AP identifying means for identifying from among the access points;
Based on the arrangement and the number of units input by the information input unit, an interference source client terminal that is estimated to be an interference source that causes radio wave interference to the target access point is identified from among the plurality of client terminals. Interference source terminal identification means;
Terminal counting means for counting the number of client terminals belonging to the interference source access point specified by the interference source AP specifying means based on the arrangement and the number of pieces inputted by the information input means;
The number of the interference source access points specified by the interference source AP specifying means, the number of the interference source client terminals specified by the interference source terminal specifying means, and the number of client terminals counted by the terminal counting means Based on the above, the callable number derivation means for deriving the maximum number of the client terminals that can make a call attributed to the target access point,
A call quality estimation system comprising: The callable number deriving means is:
The number of the interference source access points, the number of the interference source client terminals, the number of all the client terminals belonging to the interference source access point, and the maximum number of the client terminals that can make a call belonging to the target access point The call quality estimation system according to claim 1, wherein the maximum number of the client terminals that can make a call is obtained based on a reference table that is stored in association with each other in advance. The interference source AP specifying means includes:
Specifying an access point that uses the same frequency channel as the target access point and transmits a radio wave whose intensity received by the target access point is a predetermined value or more as the interference source access point of the target access point The call quality estimation system according to claim 1 or 2, wherein The interference source terminal specifying means includes:
A client terminal that uses the same frequency channel as that of the target access point and transmits a radio wave whose intensity received by the target access point is equal to or higher than a predetermined value is specified as the interference source client terminal of the target access point. The call quality estimation system according to any one of claims 1 to 3. A call quality estimation method for estimating call quality of a VoIP call performed using a plurality of access points and a plurality of client terminals of a wireless LAN,
An information input step for inputting the arrangement of the access points and the number of the client terminals;
Based on the arrangement and the number of units input in the information input step, interference source access points estimated to be interference sources that cause radio wave interference to a predetermined target access point among the plurality of access points, other An interference source AP identifying step that identifies the access point from among the access points;
Based on the arrangement and the number of units input in the information input step, an interference source client terminal that is estimated to be an interference source that causes radio wave interference to the target access point is identified from among the plurality of client terminals. Interference source terminal identification step;
A terminal counting step of counting the number of client terminals belonging to the interference source access point identified in the interference source AP identification step based on the arrangement and the number of units input in the information input step;
The number of interference source access points identified in the interference source AP identification step, the number of interference source client terminals identified in the interference source terminal identification step, and the number of client terminals counted in the terminal counting step Based on the above, a callable unit derivation step for deriving the maximum number of the client terminals that can make a call attributable to the target access point, and
A call quality estimation method comprising:

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