JP2006262403A - Radio signal transmission state estimating device, terminal device, radio signal transmission system, and radio signal transmission state estimating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To estimate accurately a receive state of a radio signal which changes specially and in time caused by multi-path interference and the like, for realizing ideal arrangement in location of a base station device and a terminal device and obtaining superior communication. <P>SOLUTION: Actual measurement information of receive strength of a radio signal at terminal devices 2a to 2f and the estimation result of the receive strength of the radio signal in relation of location of the terminal devices 2a to 2f and the base station device 1 are compared, and the receive state of the radio signal is estimated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wireless signal transmission state evaluation apparatus for measuring and evaluating a spatial and temporal distribution of a wireless signal transmission state (attenuation, interference state, etc.) in a wireless signal transmission system such as a wireless LAN system, The present invention relates to a terminal device for transmitting actual transmission state information to a wireless signal transmission state evaluation device, a wireless signal transmission system including the wireless signal transmission state evaluation device, and a wireless signal transmission state evaluation method.

A wireless signal transmission system such as a wireless LAN is known as a system capable of wirelessly transmitting and receiving information in various indoor and outdoor environments. The radio signal transmission system is a system for transmitting a radio signal in which the information is superimposed in one or both directions between a user-side terminal device and a base station device that uses the terminal device as a radio signal transmission target. It is.
In the wireless signal transmission system, it is desirable that the base station device and the terminal device be arranged in a positional relationship that enables reception of the wireless signal at a high level in order to realize as stable communication as possible. .
Therefore, when determining the positional relationship between the base station device and the terminal device, a method of acquiring the wireless signal intensity distribution information and determining the positional relationship based on the distribution information has been conventionally used. It has been.
For example, as a conventional technique for determining the most suitable arrangement position of the base station apparatus, a technique described in Patent Document 1 is known. In Patent Document 1, a relatively lightweight and portable pseudo base station is sequentially installed at the candidate positions of the base station device placement, and the wireless communication with each of the terminal devices is actually attempted. A technique for determining the position of a base station apparatus is disclosed.
A technique is also known in which a measurer moves in a communication area while carrying a wireless LAN terminal such as a notebook PC equipped with a wireless LAN card, thereby measuring the strength of a wireless signal in the communication area.

By the way, in a wireless LAN system or the like, the wireless signal is reflected by various installation objects. Such a reflected signal interferes with the original radio signal and becomes a factor that hinders the transmission of a suitable radio signal. This phenomenon is called multipath interference.
In the space without the multipath interference, the intensity of the radio signal is gradually attenuated with the distance from the base station apparatus, but when the multipath interference occurs, the intensity change of the radio signal is more severe. Arise. For example, due to a slight spatial position shift between the base station device and the terminal device, a situation occurs in which the strength of the radio signal is attenuated to a level at which communication is impossible or the strength is abnormal. obtain. In addition, the degree of multipath interference can change drastically even with changes in the environment with the movement of people. That is, multipath interference can significantly change the intensity of the radio signal with slight spatial and temporal changes.
Under the circumstances where multipath interference can occur as described above, the strength of the radio signal is uncertain as a criterion for determining the quality of the communication environment.
That is, even if the intensity of the radio signal is large, if the intensity of the radio signal increases as a result of multipath interference, a good communication state cannot be obtained. The reason is as follows. That is, the reflected signal is delayed from the original radio signal. When multipath interference occurs and the reflected signal with a delay interferes with the radio signal, the communication information superimposed on the radio signal is altered and correct information is not transmitted.
On the other hand, even if the strength of the radio signal is the minimum strength necessary for communication, if the influence of multipath interference is small, the content of communication information to be transmitted is little affected, so that relatively good communication is possible. Is possible.
JP 2002-290345 A

However, in the prior art described in Patent Document 1 described above, the wireless signal strength is merely measured in each terminal device, and even if it is determined that the wireless signal strength is weak, the base station device The communication information is not weakened as a result of attenuation with the distance of the communication, and the communication information has not changed (that is, there is no problem in communication), or the attenuation that accompanies the deterioration of communication information as a result of multipath interference. It is impossible to determine whether the error occurred (that is, there is a communication problem).
Further, Patent Document 1 discloses a specific means for determining whether the measured intensity of the radio signal is constant or whether the multipath interference changing with time is occurring. Absent.
Further, even in a technique in which a measurer moves a communication area while carrying a terminal such as a notebook PC, the measurer himself causes the multipath interference, and thus the reliability of evaluation accuracy of the state of the multipath interference is reliable. The nature was low.
Therefore, the present invention has been made in view of the above circumstances, and the object of the present invention is to provide multipath interference in order to realize an ideal base station apparatus and terminal apparatus arrangement for obtaining good communication. A wireless signal transmission state evaluation device capable of accurately evaluating the reception state of the wireless signal that varies spatially and temporally due to, for example, and transmits the actual measurement information of the transmission state to the wireless signal transmission state evaluation device It is to provide a terminal device and a radio signal transmission state evaluation method.

In order to achieve the above object, the present invention relates to a radio signal transmission system in which a radio signal transmitted from a predetermined base station apparatus is received by a plurality of terminal apparatuses, between the base station apparatus and each of the terminal apparatuses. Estimating the strength of the wireless signal estimated from the positional relationship, obtaining actual measurement information of the strength of the wireless signal by each of the terminal devices, and comparing the estimation result with the actual measurement information to The wireless signal transmission state evaluation device is configured to evaluate the reception state.
Usually, since the strength of the radio signal is attenuated with the distance from the base station apparatus, if the distance between the base station apparatus and each of the terminal apparatuses is stored in advance, the terminal apparatus in each of the terminal apparatuses The intensity of the radio signal can be estimated. By comparing such an estimated value and an actual measurement value, it is possible to obtain an evaluation of the spatial distribution of the reception state that changes due to multipath interference or the like.

Here, a part or all of the terminal device has a function of transmitting the radio signal, and the terminal device is switched from the terminal device that is not used as a base station device while sequentially switching the terminal device as the base station device. It is conceivable to evaluate the reception state of the wireless signal based on the actual measurement information of the wireless signal.
Thereby, it is possible not only to evaluate the reception state of the radio signal after the base station apparatus is fixed, but also to evaluate the desirability of each position of the base station apparatus in the same way. Can also be used as reference information when determining the position of the base station apparatus.
Further, when the actual measurement information is accumulated and stored in time series, it is possible to evaluate the time change of the reception state of the radio signal based on the stored information.
The present invention can also be understood as the terminal device constituting the wireless signal transmission system, the wireless signal transmission system including the wireless signal transmission state evaluation device, or the wireless signal transmission state evaluation method.

According to the present invention, it is possible to accurately evaluate the reception state of a radio signal that varies spatially and temporally due to multipath interference or the like, and by using such evaluation, good communication can be obtained. Therefore, it is possible to realize an ideal terminal device arrangement.
Further, part or all of the terminal device has a function of transmitting the radio signal, and the radio signal from the terminal device that is not used as a base station device while sequentially switching the terminal device as a base station device. When the reception state of the radio signal is evaluated based on the actual measurement information, it is also possible to use the evaluation as reference information when determining the position of the base station apparatus.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that the present invention can be understood. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.
FIG. 1 is a schematic diagram of a wireless signal transmission system including a wireless signal transmission state evaluation device according to an embodiment of the present invention. FIG. 2 is a block diagram showing a schematic configuration of a terminal device used in the wireless signal transmission system. 3 is a block diagram showing a schematic configuration of a radio signal transmission state evaluation device according to an embodiment of the present invention, FIG. 4 is a flowchart showing a control procedure of a reception level recording unit by a control unit of the terminal device, and FIG. 6 is a flowchart showing a processing procedure by the control unit, and FIG. 6 is a list showing the evaluation of the reception state of the wireless signal received by each of the terminal devices 2a to 2f held by the wireless signal transmission state evaluation device according to the embodiment of the present invention. FIG. 7 is a flowchart showing a processing procedure of the wireless signal transmission state evaluation apparatus according to the embodiment of the present invention.

Hereinafter, an outline of a radio signal transmission system A including a radio signal transmission state evaluation device 3 according to an embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 1, the wireless signal transmission system A is roughly configured by a plurality of terminal devices 2a to 2f, a wireless signal transmission state evaluation device 3, an Ethernet 4 and the like according to an embodiment of the present invention, and a base station This is a communication system capable of bidirectionally transmitting and receiving radio signals between the device 1 and the terminal device.
The base station device 1 is a device capable of transmitting and receiving a radio signal in accordance with a communication standard defined by, for example, IEEE 802.11. Specifically, the base station device 1 is connected to the Internet 5 and functions to convert information acquired from the Internet 5 into a radio signal in accordance with the communication standard, and the radio signal to the terminal devices 2a to 2f. It has a function to transmit.
The base station device 1 periodically transmits its ID by superimposing its own ID on a beacon signal (for example, at a cycle of 0.1 second or the like). The beacon signal is a signal that is inherently transmitted periodically from a base station in wireless communication. The beacon signal (a kind of wireless signal) is used by the wireless signal transmission state evaluation device 3 to evaluate the reception state of the wireless signal in each of the terminal devices 2a to 2f, as will be described in detail later. Specifically, it is a signal to be subjected to intensity measurement by the terminal devices 2a to 2f, and is used as actual measurement information of the reception intensity of the radio signal.

The plurality of terminal devices 2a to 2f are terminals on the radio signal receiving side. When the beacon signal is received, it is possible to measure the reception intensity (signal level at the time of reception) of the beacon signal after identifying the ID superimposed thereon. Also, the terminal devices 2a to 2f can output a beacon signal by superimposing their own IDs similarly to the base station device 1 (that is, a transmission / reception terminal device having a wireless signal transmission function). Is). In addition, when any of the terminal devices 2a to 2f emits the beacon signal, the other terminal devices 2a to 2f can measure the reception intensity after identifying the ID of the beacon signal. is there. The schematic configuration of the terminal devices 2a to 2f will be described later in detail with reference to FIG.
Each of the terminal devices 2 a to 2 f is connected to the wireless signal transmission state evaluation device 3 through the Ethernet 4. As a result, as will be described in detail later, a request for time synchronization of a communication packet (referred to as a data transmission request hereinafter) and a clock 14 (see FIG. 2) requesting transmission of measured information of the reception intensity of the beacon signal is made. A communication packet with a content (hereinafter referred to as a time synchronization request), a communication packet with a content (hereinafter referred to as a setting change request) indicating a request to change the setting of the frequency channel of a radio signal to be received by the terminal devices 2a to 2f, etc. It is possible to receive from the wireless signal transmission state evaluation device 3 and to measure the reception intensity of the beacon signal to the wireless signal transmission state evaluation device 3 (as a response to the communication packet of the data transmission request). It is possible to transmit a received intensity signal representing information.

The wireless signal transmission state evaluation device 3 is a data processing server having a CPU 6, a storage unit 7, an I / O unit 8 and the like as shown in FIG. The wireless signal transmission state evaluation device 3 can transmit the communication packet for each content request as described above to each of the terminal devices 2a to 2f.
For example, the communication packet of the data transmission request is transmitted from the I / O unit 8 to each of the terminal devices 2a to 2f, and the response is received from the I / O unit 8 (an example of reception intensity acquisition means). As a result, that is, it is possible to input (an example of acquisition) the received intensity signal that represents actual measurement information of the intensity of the beacon signal (an example of a radio signal) received by the terminal devices 2a to 2f. Further, by transmitting the communication packet of the time synchronization content and the communication packet of the setting change request, the time synchronization and strength measurement of the clock 14 (see FIG. 2) included in each of the terminal devices 2a to 2f are performed. It is possible to request a change in the frequency channel setting of the beacon signal.

Further, in the storage unit 7 (an example of the positional relationship information storage means), positional relationship information between the base station device 1 and each of the terminal devices 2a to 2f, specifically, the base station device 1 and Position information of the terminal devices 2a to 2f is stored as two-dimensional coordinate information. Using such stored contents, it is assumed that the radio signal (beacon signal) is gently attenuated with the distance from the base station apparatus 1 (that is, there is no disturbance such as multipath interference). Originally, the CPU 6 (an example of reception strength estimation means) performs arithmetic processing using the positional relationship information to estimate the reception strength of the radio signals (beacon signals) in each of the terminal devices 2a to 2f. It is possible.
Further, the CPU 6 (an example of the reception state evaluation unit) included in the wireless signal transmission state evaluation device 3 is configured such that the beacon signal (an example of the radio signal) input by the I / O unit 8 (an example of the reception intensity acquisition unit). ) Received intensity measurement information (information represented by the received intensity signal) and a result of estimation of the received intensity by the CPU 6 (an example of received intensity estimating means), multipaths in each of the terminal devices 2a to 2f. It is possible to evaluate the occurrence of interference (radio signal reception state).
Note that the wireless signal transmission state evaluation device 3 can evaluate each of the following spatial and temporal multipath interferences.
Spatial multipath interference is as follows. That is, the installation positions of the terminal devices 2a to 2f are inherently susceptible to the reflection of the radio signal, and the strength of the radio signal is constantly increased or decreased.
Temporal multipath interference is as follows. That is, there are many movements of people and the influence of reflection of the radio signal can fluctuate to a relatively high frequency with time.
A method for evaluating each of these multipath interferences will be described in detail later.

FIG. 2 is a block diagram showing a schematic configuration of each of the terminal devices 2a to 2f. 4 is a flowchart showing an operation procedure of the reception level recording unit 11 included in the terminal devices 2a to 2f, and FIG. 5 is a flowchart showing an operation procedure of the control unit 13 included in the terminal devices 2a to 2f. Hereinafter, the schematic configuration and operation of the terminal devices 2a to 2f shown in FIG. 2 will be described in detail with reference to the flowcharts of FIGS.
As shown in FIG. 2, the terminal devices 2a to 2f include a wireless LAN module 10, a reception level recording unit 11, a buffer memory 12, a control unit 13, a clock 14, and the like.
The terminal devices 2a to 2f are connected to an antenna 9, and the radio signal and the beacon signal transmitted from the base station device 1 (and the terminal devices 2a to 2f other than itself) via the antenna 9 are used. Enter. The wireless signal and the beacon signal are input to the wireless LAN module 10 that operates according to the IEEE 802.11 standard. The wireless LAN module 10 identifies the ID superimposed on the beacon signal transmitted from the base station device 1 (the terminal devices 2a to 2f other than itself), and the beacon signal is the base station device 1 Or the terminal device 2a-2f other than itself is discriminated.
The wireless LAN module 10 (an example of signal strength detection means) determines the reception strength of the beacon signal, and stores the determination result in the internal memory of the wireless LAN module 10 in association with the ID.
The above is automatically performed by the wireless LAN module 10 every time the beacon signal is input regardless of the control of the control unit 13.

Hereinafter, the operation procedure of the reception level recording unit 11 will be described with reference to FIG. In each procedure shown in FIG. 4, the control unit 13 controls the reception level recording unit 11 while referring to the timing information by the clock 14 in accordance with a control program stored in the storage unit (ROM). It is executed by doing. S101, S102... Shown in FIG. 4 represent numbers of operation procedures (steps), and when the energization of the terminal devices 2a to 2f is started, or a predetermined state evaluation start notice signal by the wireless signal transmission state evaluation device 3 Is started from the operation of step S101.
In step S101, the control unit 9 refers to the timekeeping information by the clock 14 and determines whether or not a predetermined time (for example, 1 second) has elapsed. Note that the period at which the base station apparatus 1 transmits the beacon signal is known, and the predetermined time may be determined accordingly and input at the time of initial setting of the terminal apparatuses 2a to 2f. For example, if the beacon signal transmitted by the base station apparatus 1 is to be subjected to strength measurement, the predetermined time and the period are made the same.
If it is determined that the predetermined time has elapsed, the process proceeds to step S102 (YES in S101), while the determination in step S101 is repeated unless it is determined that the predetermined time has elapsed (NO in S101).
In step S102, the control unit 13 controls the reception level recording unit 11, and automatically measures the reception intensity of the beacon signal stored in the internal memory of the wireless LAN module 10 and the ID as described above. Is read out.
In step S103 following step S102, the control unit 13 controls the reception level recording unit 11 to associate the beacon signal reception intensity, the ID, the frequency channel, and the current time indicated by the clock 14 with the buffer memory. 12 is stored. The buffer memory 12 is a ring buffer. When the capacity is full, old data is erased.
In step S104 following step S103, the control unit 13 controls the reception level recording unit 11 (when the communication packet for the setting change request is received), and the wireless LAN module 10 performs measurement (reception strength). Set the frequency channel to perform.

Hereinafter, the processing procedure of the control unit 13 will be described with reference to FIG. Each procedure shown in FIG. 5 is executed by the control unit 13 referring to the time measurement information by the clock 14 in accordance with a control program stored in the storage unit (ROM). S201, S202,... Shown in FIG. 5 represent the numbers of operation procedures (steps). When the energization of the terminal devices 2a to 2f is started, a predetermined state evaluation start notice signal by the wireless signal transmission state evaluation device 3 Is started from the operation of step S201.
In step S201, the control unit 13 waits to receive a communication packet from the wireless signal transmission state evaluation device 3. When the communication packet is received, the process proceeds to the next step S202 (YES in S201), and waits until it is received (NO in S201).

In step S202, the control unit 13 (an example of signal strength transmission means) determines whether or not the content of the communication packet is a communication packet for a data transmission request. If it is a data transmission request (YES in S202), the process proceeds to S203, and among the information on the reception strength of the radio signal stored in the buffer memory 12, information associated with the latest current time (hereinafter referred to as reception). Strength information) is determined and transmitted to the wireless signal transmission state evaluation device 3 as a received strength determination signal. On the other hand, if the data transmission is not requested (NO in S202), the process proceeds to step S204.
In step S204, the control unit 13 determines whether or not the content of the communication packet is a setting change request. If it is determined that the request is a setting change request (YES in S204), the process proceeds to step S205, the frequency channel designated by the wireless signal transmission state evaluation device 3 is read from the communication packet, and the reception level recording unit 11 is controlled. Then, the wireless LAN module 10 sets a frequency channel for measuring (reception strength) (the same content as the above-described step S104). On the other hand, if it is determined that it is not a setting change instruction (NO in S204), the process proceeds to step S206.
In step S206, the control unit 13 determines whether or not the content of the communication packet is a time synchronization request, and if it is a time synchronization request (YES in S206), the process proceeds to S207. In S207, the time of the clock 14 is set based on the time synchronization information superimposed on the communication packet. On the other hand, if it is not a time synchronization request, the process returns to step S1 (RETURN).

FIG. 6 is a list representing the strength of the beacon signal received by each of the terminal devices 2a to 2f and the evaluation of the reception state of the beacon signal held by the wireless signal transmission state evaluation device 3.
The list is stored in advance in the storage unit 7, and the wireless signal transmission state evaluation device 3 sequentially updates the list when receiving the reception strength information from each of the terminal devices 2a to 2f.
The list has the following data structure. That is, ID information 62, position information 63, received intensity list information 64, multipath interference evaluation information 65, and the like are associated with the identification information 61 of each of the terminal devices 2a to 2f. The ID information 62 is information for specifying a transmission source when the reception strength information is received. The position information 63 represents the position of each of the terminal devices 2a to 2f in coordinates. The reception strength list information 64 is a result of measuring the reception strength of the radio signal for a predetermined number of times (N times) by each of the terminal devices 2a to 2f indicated by the reception strength information, in other words, N seconds (predetermined) This is actual measurement information of the reception intensity of the beacon signal over one example of the time zone. The multipath interference evaluation information 65 includes the multipath interference in each of the spatial and temporal directions based on a comparison between the reception strength list information 64 and a prediction result of the reception strength of the beacon signal estimated from the position information 63. It is a discrimination result.
Here, the position information 63 may be a distance from the base station apparatus 1. In addition, when the reception intensity of the beacon signal can be estimated to some extent, it is conceivable to store such estimation information.
The storage unit 7 for accumulating and storing the actual measurement information based on the reception intensity list information 64 is an example of the reception intensity accumulation storage unit.

FIG. 7 is a flowchart showing a processing procedure of the wireless signal transmission state evaluation device 3. Hereinafter, the processing procedure of the wireless signal transmission state evaluation apparatus 3 will be described with reference to FIG. Each procedure shown in FIG. 7 is performed according to a control program stored in the storage unit 7 by the wireless signal transmission state evaluation device 3 and also counted by a timer (not shown) of the wireless signal transmission state evaluation device 3. It is executed while referring to the information. S301, S302,... Shown in FIG. 7 represent operation procedure (step) numbers, which are started from the operation of step S301.
In step S301, whether or not a communication packet representing a time synchronization request should be transmitted to the terminal devices 2a to 2f by referring to the timing information by the timer by the calculation of the CPU 6 of the wireless signal transmission state evaluation device 3 Determine whether or not. The timing rule for making the time synchronization request is, for example, a rule such as once per hour is stored in the storage unit 7, and the step S301 is performed by collating the timing information with the rule. Execute the process. If it is determined that it should be transmitted (YES in S301), the process proceeds to S302, where a communication packet representing the time synchronization request is transmitted from the I / O unit 8 to the terminal devices 2a to 2f, and transmitted. If it is determined that it should not be (NO in S301), the process proceeds to S303.

In S303, whether or not a communication packet representing a setting change request should be transmitted to the terminal devices 2a to 2f by referring to the timing information by the timer by the calculation of the CPU 6 of the wireless signal transmission state evaluation device 3 Is determined. It should be noted that a timing rule for performing the time synchronization request is also stored in the storage unit 7 (such as once per minute), and the processing is executed by checking the time keeping information against the rule. If it is determined that it should be transmitted (YES in S303), the process proceeds to S304, where a communication packet representing the setting change request is transmitted from the I / O unit 8 to the terminal devices 2a to 2f, and transmitted. If it is determined that it should not be (NO in S303), the process proceeds to S305.
In S305, whether or not to transmit a communication packet indicating a data transmission request to the terminal devices 2a to 2f by referring to the timing information by the timer by the calculation of the CPU 6 of the wireless signal transmission state evaluation device 3 Is determined. It should be noted that a timing rule for making the data transmission request is also stored in the storage unit 7 (such as once per second), and the processing is executed by checking the time keeping information against the rule. If it is determined that it should be transmitted (YES in S305), the process proceeds to S306, where the wireless signal transmission state evaluation device 3 sends a communication packet indicating the data transmission request from the I / O unit 8 to the terminal device 2a. On the other hand, if it is determined that it should not be transmitted (NO in S305), the process returns to S301.

In step S307, the wireless signal transmission state evaluation device 3 receives a response from the terminal devices 2a to 2f in response to the data transmission request, that is, receives the reception strength determination signal representing reception strength information, and the terminal devices 2a to 2f. The strength of the beacon signal discriminated at each is read from the received strength discriminating signal. Further, the reception intensity list information 64 is updated based on the read information.
In step S308 following step S307, the wireless signal transmission state evaluation device 3 receives responses from all the terminal devices 2a to 2f, and determines whether or not the reception strength list information 64 has been updated. Until all responses are received (NO in S308), the process returns to S306 and the processes in steps S306 to S308 are repeated. On the other hand, if responses from all are received (YES in S308), the received intensity list information 64 is returned. Upon completion of the update, the process proceeds to step S309.

In step S309, the wireless signal transmission state evaluation device 3 refers to the time measurement information by the timer to determine whether or not to evaluate multipath interference. Note that the rule of the timing to evaluate the multipath interference is, for example, a rule such as once every 10 minutes is stored in the storage unit 7, and the step is performed by checking the time information with the rule. The process of S309 is executed. If it is determined that the multipath interference should not be evaluated (NO in S309), the process returns to step S301. If it is determined that the evaluation should be performed (YES in S309), the process proceeds to step S310.
In step S310, the wireless signal transmission state evaluation device 3 performs a spatial multipath at each position of the terminal devices 2a to 2f by arithmetic processing of the CPU 6 based on the position information 63 and the received intensity list information 64. Determine whether there is interference.
Whether or not there is spatial multipath interference is determined as follows. That is, the reception intensity of the beacon signal in each of the terminal apparatuses 2a to 2f predicted from the position information 63 (hereinafter, predicted intensity) and the reception intensity determination signal received from the terminal apparatuses 2a to 2f are represented. A comparison is made with the received intensity of the beacon signal (hereinafter, measured intensity), and when the measured and predicted values are far from each other, it is determined that there is multipath interference. Whether or not there is multipath interference spatially is determined by using only the latest information (“current” shown in FIG. 6) in the reception intensity list information 64, and therefore the determination result is also the latest. This represents the state.
Here, it is also conceivable to calculate a ratio between actual measurement and prediction instead of the deviation.

但し，（ｘ，ｙ）は前記位置情報６３の表す前記端末装置２ａ〜２ｆの座標，（ａ，ｂ）は前記基地局装置１の座標，λは予め定められた定数，α，Ｐ_tは前記実測情報（前記受信強度リスト情報６４）から決定すべき定数である。
前記ＣＰＵ６は，前記実測強度を式（１）に適用し，最小二乗法等のフィッティングによりα，Ｐ_tを決定する。尚，α，Ｐ_tは既知であるとしてその値を予め前記記憶部７に記憶しておいても良い。
また，前記ＣＰＵ６は，α，Ｐ_tの決定により確定された（１）式に，前記端末装置２ａ〜２ｆの座標を代入する。その代入の結果得られたｆ（ｘ，ｙ）が前記端末装置２ａ〜２ｆ各々の位置における予測強度であり，マルチパス干渉等の外乱要素がない場合には実測強度と略一致すべき値である。
更に，前記無線信号伝送状態評価装置３は前記実測強度と前記予測強度との偏差（絶対値）を算出し，該偏差が所定の閾値以上か否かを判別する。前記偏差が閾値以下である場合には，その端末装置２ａ〜２ｆの周囲ではマルチパス干渉が生じていないと判別する。一方，前記偏差が前記閾値を上回る場合には，マルチパス干渉が生じていると判別する。以上がステップＳ３１０の処理内容である。 Prediction of the reception intensity of the beacon signal by the wireless signal transmission state evaluation device 3 is performed as follows. That is, it is assumed that the reception intensity of the beacon signal is gradually attenuated based on the distance from the base station apparatus 1 according to, for example, the -log type, and the following equation (1) is assumed.

Where (x, y) are the coordinates of the terminal devices 2a to 2f represented by the position information 63, (a, b) are the coordinates of the base station device 1, λ is a predetermined constant, and α and P _t are It is a constant to be determined from the actual measurement information (the reception strength list information 64).
The CPU6 is the measured intensity is applied to Equation (1), the fitting of such a least square method alpha, determining the P _t. Note that α and _Pt may be known and their values may be stored in the storage unit 7 in advance.
Further, the CPU6 is, alpha, in the determined by the determination of P _t (1) formula, substituting the coordinates of the terminal device 2a to 2f. F (x, y) obtained as a result of the substitution is a predicted intensity at the position of each of the terminal devices 2a to 2f. If there is no disturbance element such as multipath interference, the value should be approximately equal to the actually measured intensity. is there.
Further, the wireless signal transmission state evaluation device 3 calculates a deviation (absolute value) between the actually measured intensity and the predicted intensity, and determines whether the deviation is equal to or greater than a predetermined threshold value. When the deviation is equal to or smaller than the threshold value, it is determined that multipath interference does not occur around the terminal devices 2a to 2f. On the other hand, when the deviation exceeds the threshold, it is determined that multipath interference has occurred. The above is the processing content of step S310.

In step S311 following step S310, the radio signal transmission state evaluation device 3 determines temporal multipath interference.
When temporal multipath interference occurs with movement of a person, operation of an installation, etc., the degree of interference of the beacon signals received by the terminal devices 2a to 2f changes with time, and similarly The reception strength also changes. Accordingly, in step S311, such a temporal change in reception intensity is measured. As described above, the reception strength list information 64 includes measurement results based on the reception strength measurement results of the radio signal for a predetermined number of times (N times) by each of the terminal devices 2a to 2f (see FIG. 6). That is, it is considered to be time series information of the received intensity (the measured intensity) from the present to a certain period. The CPU 6 (an example of a reception state evaluation unit) is configured to transmit the beacon signal (radio signal) in each of the terminal devices 2a to 2f based on the storage information as described above in the storage unit 7 (an example of a reception intensity accumulation storage unit). ) Temporal multipath interference (an example of a reception state) is evaluated as follows.
The wireless signal transmission state evaluation device 3 calculates an average value of the measurement results (measured strengths) of the N received strengths included in the received strength list 64 for each of the terminal devices 2a to 2f. Further, the deviation (absolute value) is calculated by comparing each of the N measurement results with the average value, and any one of the deviations exceeds a deviation threshold value stored in advance in the storage unit 7 Is determined to have temporal multipath interference around the terminal device. The above is the content of step S311.
On the other hand, as another example of step S311 for determining temporal multipath interference, the following processing may be considered. In other words, the wireless signal transmission state evaluation device 3 calculates a variance value of the N reception strength measurement results (the actually measured strengths) included in the reception strength list 64. When the calculated dispersion value exceeds the dispersion threshold value stored in advance in the storage unit 7, the wireless signal transmission state evaluation device 3 assumes that temporal multipath interference occurs around the terminal device. Determine.

When step S311 ends, the process proceeds to step S312. In step S312, the wireless signal transmission state evaluation device 3 determines the list (FIG. 6) based on the determination result of the spatial multipath interference in step S310 and the determination result of the temporal multipath interference in step S311. The multipath interference evaluation information 65 in the reference) is updated. Further, the updated multipath interference evaluation information 65 is output as an evaluation result.
As an output method, a method of displaying the list of FIG. 6 on a display connected to the wireless signal transmission state evaluation device 3 or an image forming apparatus (printer) connected to the wireless signal transmission state evaluation device 3 A method of causing the list to be printed is also conceivable. Further, when it is determined that any one of the terminal devices 2a to 2f is in an undesired communication environment due to multipath interference, a warning signal or the like indicating a request for changing a set position or the like is given to the terminal device. A case of transmission is also conceivable. In this way, it is determined whether or not the communication environment is good, and it is possible to prompt the terminal device that is not good to change the installation position. As a result, the terminal devices 2a to 2f are well arranged. Is realized.
When step S312 ends, the process returns to step S1.
As described above, the wireless signal transmission state evaluation device 3 obtains the reception strength of the beacon signals received by the terminal devices 2a to 2f, and analyzes the reception strength to generate spatially and temporally. It is possible to evaluate the multipath interference to be performed, and it is possible to realize the arrangement of the terminal devices 2a to 2f so as to obtain a good communication state based on the evaluation result.

As described above, the terminal devices 2a to 2f are transmission / reception type terminal devices capable of transmitting beacon signals with their IDs superimposed. The radio signal transmission state evaluation device 3 can output a control signal for causing the terminal devices 2a to 2f to function as base station devices from the I / O unit 8 (an example of base station setting means). is there.
Thereby, the said radio | wireless signal transmission-state evaluation apparatus 3 can evaluate the desirability for each installation position when the said base station apparatus 1 is provided in the present installation position of each of the said terminal devices 2a-2f. It is.
That is, a list as shown in FIG. 6 is created each time the terminal device that functions as the base station device is set, and the identification number of the terminal device functioning as the base station device (superimposed on the beacon signal). And stored in the storage unit 7 in association with each other. In the list, the reception strength signal received from the terminal devices 2a to 2f other than the terminal device functioning as a base station device via the I / O unit 8 (an example of reception strength acquisition means). Is recorded as the received strength list information 64. Based on such information, the CPU 6 (an example of reception state evaluation means) evaluates spatial and temporal multipath interference (reception state of radio signals) by the processing of steps S310 and S311 shown in FIG. To do.

In the above-described example, the base station device 1 and the terminal devices 2a to 2f transmit and receive radio signals bidirectionally, but the present invention is not limited to this. That is, a radio signal may be transmitted from the base station device 1 to the terminal devices 2a to 2f in one direction, so-called broadcast form.
Moreover, although the said terminal device 2a-2f disclosed about the example which transmits / receives a communication packet and a radio | wireless intensity | strength signal via the wireless signal transmission state evaluation apparatus 3 and the Ethernet 4, it is carrying out wireless communication instead of the said Ethernet 4. You may use.
Furthermore, the terminal devices 2a to 2f are not limited to installation-type terminals installed at predetermined locations, and vehicles equipped with wireless devices (that is, mobile terminals) can be considered. Multipath interference is known to have a particularly adverse effect on such mobile terminals, and thus the effect of the present invention is considered to be particularly conspicuous.
Moreover, although the example in which the wireless signal transmission state evaluation device 3 is provided outside each of the terminal devices 2a to 2f has been disclosed, the present invention is not limited to this, and any one of the terminal devices 2a to 2f is connected to the wireless device. A function as a signal transmission state evaluation device may be provided, and the reception strength state evaluation may be performed by aggregating measurement information of reception strengths represented by the wireless strength signals from the other terminal devices 2a to 2f.

1 is a schematic diagram of a wireless signal transmission system including a wireless signal transmission state evaluation device according to an embodiment of the present invention. The block diagram showing the schematic structure of the terminal device used with a radio signal transmission system. 1 is a block diagram illustrating a schematic configuration of a wireless signal transmission state evaluation device according to an embodiment of the present invention. The flowchart which shows the control procedure of the reception level recording part by the control part which a terminal device has. The flowchart which shows the process sequence by the control part which a terminal device has. The list showing evaluation etc. of the reception state of the radio signal received by each of the terminal devices 2a to 2f held by the radio signal transmission state evaluation device according to the embodiment of the present invention. The flowchart which shows the process sequence of the radio | wireless signal transmission state evaluation apparatus which concerns on embodiment of this invention.

Explanation of symbols

A ... Wireless signal transmission system 1 ... Base station device 2 ... Terminal device 3 ... Wireless signal transmission state evaluation device 4 according to an embodiment of the present invention ... Ethernet 5 ... Internet 6 ... CPU
7 ... Storage unit 8 ... I / O unit 9 ... Antenna 10 ... Wireless LAN module 11 ... Reception level recording unit 12 ... Buffer memory 13 ... Control unit 14 ... Clock

Claims (7)

A radio signal transmission state evaluation device for evaluating a reception state of the radio signal by each of the terminal devices for a radio signal transmission system in which a radio signal transmitted from a predetermined base station device is received by a plurality of terminal devices,
Positional relationship information storage means for storing positional relationship information between the base station device and each of the terminal devices;
Reception strength estimation means for estimating the reception strength of the radio signal in each of the terminal devices based on the positional relationship information;
Reception intensity acquisition means for acquiring actual measurement information of the reception intensity of the radio signal from each of the plurality of terminal devices;
A reception state evaluation unit that evaluates a reception state of the radio signal in each of the terminal devices based on a comparison between an estimation result by the reception strength estimation unit and acquisition information by the reception strength acquisition unit;
A radio signal transmission state evaluation apparatus comprising:   The radio signal transmission state evaluation device according to claim 1, wherein the reception state evaluation unit evaluates a state of multipath interference of the radio signal in each of the terminal devices. A part or all of the plurality of terminal devices are transmission / reception type terminal devices having a function of transmitting the radio signal,
Comprising base station setting means for causing a plurality of the transmission / reception type terminal devices to sequentially function as the base station devices one by one,
The reception strength obtained by the reception strength acquisition unit from the other terminal device each time the transmission / reception type terminal device that the reception state evaluation unit causes the base station setting unit to function as the base station device is set. The radio signal transmission state evaluation apparatus according to claim 1, wherein the reception state of the radio signal in each of the terminal apparatuses is evaluated based on the actual measurement information. A reception strength accumulation storage means for accumulating and storing the measurement information of the reception strength over a predetermined time period;
The radio signal transmission according to any one of claims 1 to 3, wherein the reception state evaluation unit evaluates a reception state of the radio signal in each of the terminal devices based on information stored in the reception intensity accumulation storage unit. Condition evaluation device. A terminal device constituting a radio signal transmission system in which a radio signal transmitted from a predetermined base station device is received by a plurality of terminal devices,
Signal strength detection means for detecting the strength of the radio signal received from the base station device;
A wireless signal transmission state in which the detection result by the signal strength detection means is provided in the terminal device or an external device connected to be communicable with the terminal device, and the reception state of the wireless signal by each of the plurality of terminal devices is evaluated. A signal strength transmitting means for transmitting to the evaluation device;
The terminal device which comprises the radio signal transmission system characterized by comprising. A radio signal transmission system in which radio signals transmitted from a predetermined base station apparatus are received by a plurality of terminal apparatuses,
A plurality of terminal devices capable of detecting the strength of the radio signal received from the base station device;
A wireless signal transmission state evaluation device according to any one of claims 1 to 4,
A wireless signal transmission system comprising: A wireless signal transmission state evaluation method for evaluating a reception state of the wireless signal by each of the terminal devices for a wireless signal transmission system in which wireless signals transmitted from a predetermined base station device are received by a plurality of fixedly arranged terminal devices There,
A reception strength estimation step of estimating the reception strength of the radio signal in each of the terminal devices based on the positional relationship information between the base station device and each of the terminal devices stored in advance in storage means;
A reception strength acquisition step of acquiring measured information of the reception strength of the radio signal from each of the plurality of terminal devices;
A reception state evaluation step for evaluating a reception state of the radio signal in each of the terminal devices based on a comparison between an estimation result obtained by the reception strength estimation step and acquisition information obtained by the reception strength acquisition step;
A wireless signal transmission state evaluation method comprising:

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