JP6163328B2 - Communication state evaluation apparatus and method for wireless network - Google Patents

Description

  The present invention relates to a communication state evaluation apparatus and method for evaluating a communication state of a route of a wireless network.

  The management system for managing the wireless field devices in the plant conforms to the international standard ISA100.11a, and commercialization is proceeding in accordance with this standard. In ISA100.11a, the state of wireless communication can be acquired via a gateway compliant with ISA100.11a. However, the communication status between specific devices cannot be known only by the functions supported by ISA100.11a.

The functions supported by the international standard ISA100.11a include the following.
(A) Communication quality acquisition function between adjacent devices.
(B) Communication quality acquisition function for the entire network.
(C) Communication quality acquisition function for each device (between wireless gateway and device).

  With the function (A), the communication state of each link between adjacent devices can be known, but the communication state between devices not adjacent to each other cannot be known. With the functions (B) and (C), the communication state between the wireless gateway and the device can be known, but the quality of communication between the device and a specific repeater cannot be known. It is difficult to perform macro evaluation (determining whether the communication of the device is good or bad) with only the information based on the function (A), and local evaluation limited to a specific range with only the information based on the function (B) or (C). Is difficult.

  For example, in regular maintenance, it is necessary to know not only the communication state between the wireless gateway and the device but also the communication state to the relay device and the sensor device for relay. As the number of devices increases as in an actual plant, the size of the wireless network increases. Therefore, in addition to between the wireless gateway and the device, a method for calculating the communication state between any devices within the range required by the engineer performing maintenance is necessary. That is, when a plurality of wireless devices are re-installed due to regular maintenance or the like, it is necessary to evaluate reproducibility for each wireless communication path.

  As a technique for evaluating such a communication path, for example, there is a technique disclosed in Patent Document 1. The technique disclosed in Patent Document 1 counts the number of transmissions between wireless devices via a wireless network and the number of non-replies indicating the number of replies to this transmission, and the number of transmissions and the number of no replies The stability of the route through which the transmission was performed is calculated.

JP 2012-138830 A

  In the technique disclosed in Patent Document 1, the stability of a single path is calculated. However, since there are multiple candidate routes (primary path and secondary path) in the wireless route, and the route is variable, the stability of a single link or route depends on the communication status of the wireless device in the wireless mesh network. It is not very suitable as an index for judging good or bad. That is, in the mesh network, the path may change depending on the communication status, and therefore, there is a possibility that an erroneous evaluation is performed only by evaluating the communication state for each link.

  For example, when the number of repeaters is increased due to maintenance and the number of hoppings is increased, the communication state of each link is improved. However, when the communication state is viewed in total, it may be deteriorated. In such a situation, when an engineer tries to evaluate the communication state of each link, the engineer may vary in judgment, and a serious problem may be overlooked.

  The present invention has been made to solve the above-described problem, and can determine the communication state of the route of the wireless network with one index, and can suppress the variation in judgment by the engineer. An object is to provide an evaluation apparatus and method.

The wireless network communication state evaluation apparatus according to the present invention includes wireless communication state information acquisition means for acquiring wireless communication state information indicating a wireless communication state of a wireless device on a path to be evaluated in the wireless network, and the wireless communication state information. Based on the link individual stability calculation means for calculating the stability of a link connecting adjacent wireless devices on a plurality of candidate paths that may be used as the evaluation target path, and the link individual stability Based on the normalized link individual stability calculating means for weighting the link stability calculated by the degree calculating means by the usage rate of the link and calculating the normalized stability, and the normalized link stability, Based on the path individual stability calculating means for calculating the stability of the plurality of candidate paths and the stability of the plurality of candidate paths, the total safety of the paths to be evaluated is calculated. It is characterized in that and a total evaluation value calculating means for calculating a degree.
The wireless network communication state evaluation apparatus according to the present invention includes wireless communication state information acquisition means for acquiring wireless communication state information indicating a wireless communication state of a wireless device on a path to be evaluated in the wireless network, and the wireless communication Link individual stability calculating means for calculating the stability of a link connecting adjacent wireless devices on a plurality of candidate routes that may be used as the evaluation target route based on the state information; and the link Based on the stability of each of the plurality of candidate routes based on the stability of the plurality of candidate routes, the total stability of the route to be evaluated is calculated based on the stability of the plurality of candidate routes. The total evaluation value calculation means for comparing the total stability of the route to be evaluated with a preset threshold value, and the communication state of the route to be evaluated is stable. It is characterized in further comprising a determining means for determining whether or not.

The wireless network communication state evaluation apparatus according to the present invention may further include a communication state evaluation device that compares the total stability of the evaluation target route with a preset threshold value. It is characterized by comprising a judging means for judging whether or not is stable.
In addition, one configuration example of the communication state evaluation device for a wireless network according to the present invention further specifies the plurality of candidate routes, and specifies a candidate route that specifies a link connecting adjacent wireless devices on the candidate route. Means are provided.
Further, in one configuration example of the wireless network communication state evaluation apparatus according to the present invention, the wireless communication state information is sent back between the adjacent wireless devices on the candidate route and the transmission between the adjacent wireless devices. It is the number of failures indicating the number that did not exist, the number of transmissions between adjacent wireless devices on the candidate route, and the number of successes indicating the number of replies to transmissions between adjacent wireless devices.

The wireless network communication state evaluation method of the present invention includes a wireless communication state information acquisition step of acquiring wireless communication state information indicating a wireless communication state of a wireless device on an evaluation target route in the wireless network, and the wireless communication A link individual stability calculation step for calculating the stability of a link connecting adjacent wireless devices on a plurality of candidate paths that may be used as the evaluation target path based on the state information, and this link Based on the normalized link individual stability calculation step for calculating the normalized stability by weighting the link stability calculated in the individual stability calculation step with the usage rate of the link, and the normalized link stability The path individual stability calculating step for calculating the stability of the plurality of candidate paths, and the evaluation based on the stability of the plurality of candidate paths. It is characterized in that comprises a total evaluation value calculating step of calculating the total stability of the target path.
The wireless network communication state evaluation method of the present invention includes a wireless communication state information acquisition step of acquiring wireless communication state information indicating a wireless communication state of a wireless device on an evaluation target route in the wireless network, and the wireless communication A link individual stability calculating step for calculating stability of a link connecting adjacent wireless devices on a plurality of candidate paths that may be used as the evaluation target path based on the state information; and The individual stability calculation step for calculating the stability of the plurality of candidate routes based on the stability of the plurality of candidate routes, and the total stability of the evaluation target route based on the stability of the plurality of candidate routes Comparing the total evaluation value calculating step to the total stability of the route to be evaluated and a preset threshold value, and communicating the route to be evaluated State is characterized in that comprising a determination step of determining whether or not stable.

  According to the present invention, by providing the wireless communication state information acquisition means, the link individual stability calculation means, the path individual stability calculation means, and the total evaluation value calculation means, one total of the total stability of the route to be evaluated is provided. Since it is possible to calculate an index and obtain an index that evaluates a plurality of candidate routes in total, it is possible to suppress variations in judgments by engineers and reduce the possibility of overlooking serious problems. . In the present invention, it is possible to reduce the possibility of taking unnecessary measures against stability deterioration or overlooking necessary stability deterioration measures.

  In the present invention, the link stability calculated by the link individual stability calculation means is weighted by the usage rate of the link, and the normalized stability is calculated, whereby the total stability of the route is set to 0 to 1. 0.0, and the communication state of the evaluation target path can be evaluated with one threshold.

  Further, in the present invention, by providing candidate route specifying means, a plurality of candidate routes (primary path, secondary path) that may be used as a route to be evaluated and between adjacent wireless devices on this candidate route Can be specified.

It is a block diagram which shows the structure of the communication state evaluation apparatus which concerns on embodiment of this invention. It is a flowchart which shows operation | movement of the communication state evaluation apparatus which concerns on embodiment of this invention. It is a figure which shows the example of the wireless network used as the evaluation object of the communication status evaluation apparatus which concerns on embodiment of this invention. It is a figure which shows the example of the frequency | count of transmission between the radio | wireless apparatuses in embodiment of this invention, and the frequency | count of failure. It is a figure which shows the other example of the frequency | count of transmission between the radio | wireless apparatuses and the frequency | count of failure in embodiment of this invention.

[Principle of the Invention]
When a plurality of wireless devices are installed, for example, the stability of the communication path A (path A) and the communication path B (path B) may change simultaneously. The inventor noticed that the evaluation could be insufficient only by the evaluation limited to individual paths. For example, when the stability of the primary path is the same level as before reconstruction, if the evaluation is performed using only the primary path, there is a risk of overlooking the situation where the secondary path is not functioning. Accordingly, the inventor has conceived that the risk of overlooking the secondary path can be reduced by evaluating a plurality of paths (paths) in total. In the present invention, it is possible to reduce the possibility of unnecessarily inducing a stability degradation countermeasure due to an error in the evaluation of the communication state, and to reduce the risk of overlooking the necessary stability degradation countermeasure.

[Embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, information indicating the communication state of a wireless device is acquired, and link stability is calculated for all of one or more routes between specific devices from the acquired information. The stability of the total wireless connection between devices is calculated from the calculated stability data group of each link related to a specific device using a method such as weighting.

  FIG. 1 is a block diagram showing a configuration of a communication state evaluation apparatus according to an embodiment of the present invention. The communication state evaluation device specifies a plurality of candidate routes that may be used as a route to be evaluated and a candidate route specifying unit 1 that specifies a link connecting adjacent wireless devices on the candidate route. The wireless communication state information acquisition unit 2 that acquires wireless communication state information indicating the wireless communication state of wireless devices on the candidate route, and between adjacent wireless devices on the plurality of candidate routes based on the wireless communication state information A link stability calculation unit 3 that calculates the stability of a link to be connected, a path individual stability calculation unit 4 that calculates the stability of a plurality of candidate routes based on the link stability, and a stability of a plurality of candidate routes The total evaluation value calculation unit 5 that calculates the total stability of the evaluation target route based on the degree of evaluation, and compares the total stability of the evaluation target route with a preset threshold, Letter of communication Consists of determining unit 6 which whether stable.

  The wireless communication state information acquisition unit 2 includes a transmission number acquisition unit 20 and a transmission failure number acquisition unit 21. The link stability calculation unit 3 includes a link individual stability calculation unit 30 and a normalized link individual stability calculation unit 31.

  Hereinafter, the operation of the communication state evaluation apparatus according to the present embodiment will be described. FIG. 2 is a flowchart showing the operation of the communication status evaluation apparatus, and FIG. 3 is a diagram showing an example of a wireless network to be evaluated according to this embodiment. The wireless devices 10-A, 10-B, 10-C, 10-D, and 10-X in FIG. 3 are devices such as a repeater and a wireless gateway.

  First, when the candidate route specifying unit 1 evaluates a route between the wireless device 10-A and the wireless device 10-X, for example, according to an instruction from an engineer (user), the wireless device 10-A and the wireless device 10- A candidate route (primary path, secondary path) between X is specified, and a link connecting adjacent wireless devices on the candidate route is specified (step S1 in FIG. 2). The function of the candidate route specifying unit 1 can be realized by the function of the system manager that manages the network. That is, the system manager can acquire information between the wireless device 10-A and the wireless device 10-X, and can identify a candidate route using a technique disclosed in, for example, Japanese Patent No. 3755881.

  Information on adjacent wireless devices connected by a wireless network and information on links connecting these wireless devices can be acquired from a gateway conforming to ISA100.11a. Therefore, if a candidate route can be specified, it goes without saying that a link connecting adjacent wireless devices on the candidate route can be easily specified.

  For example, in the example illustrated in FIG. 3, the path of wireless device 10 -A → wireless device 10 -B → wireless device 10 -X is the primary path, and wireless device 10 -A → wireless device 10 -B → wireless device 10-. The route C → wireless device 10-X and the route wireless device 10-A → wireless device 10-D → wireless device 10-X are secondary paths. The wireless device 10-A and the wireless device 10-B are connected by a link 11-AB, the wireless device 10-A and the wireless device 10-D are connected by a link 11-AD, and the wireless device 10-B and the wireless device are connected. 10-C is connected by a link 11-BC, the wireless device 10-B and the wireless device 10-X are connected by a link 11-BX, and the wireless device 10-C and the wireless device 10-X are connected by a link 11-. The wireless device 10-D and the wireless device 10-X are connected by a link 11-DX.

  Subsequently, the wireless communication state information acquisition unit 2 acquires wireless communication state information indicating the wireless communication state of the wireless device on the candidate route specified by the candidate route specifying unit 1 (step S2 in FIG. 2). The wireless communication status information includes the number of transmissions between adjacent wireless devices and the number of failures indicating the number of transmission replies (Ack) between adjacent wireless devices. The transmission number acquisition unit 20 acquires information on the number of transmissions between adjacent wireless devices (links) on the candidate route. The transmission failure number acquisition unit 21 acquires information on the number of failures between adjacent wireless devices (links) on the candidate route. The number of transmissions and the number of failures are counted along with data communication and communication for maintaining a connection between devices. Information on the number of transmissions and the number of failures can be acquired from a gateway conforming to ISA100.11a.

Next, the link individual stability calculation unit 30 connects the adjacent wireless devices on the candidate route based on the wireless communication state information (the number of transmissions and the number of failures) acquired by the wireless communication state information acquisition unit 2. Is calculated (step S3 in FIG. 2). When the number of transmissions between adjacent wireless devices 10-i and 10-j on the candidate route is T_ {ij} and the number of failures is T _{fail_} {ij}, the wireless device 10-i and the wireless device 10- The stability S_ {ij} of the links connecting j is expressed by the following equation.
S_ {ij} = 1− (T _fail _ {ij} / T_ {ij}) (1)

When evaluating the route between the wireless device 10-A and the wireless device 10-X illustrated in FIG. 3, the links connecting adjacent wireless devices on the candidate route are the links 11-AB, 11-AD, 11 as described above. -BX, 11-BC, 11-CX, 11-DX. Stability S_ {AB} of the link 11-AB connecting the wireless device 10-A and the wireless device 10-B, and stability S_ of the link 11-AD connecting the wireless device 10-A and the wireless device 10-D {AD}, stability S_ {BX} of the link 11-BX connecting the wireless device 10-B and the wireless device 10-X, link 11-BC connecting the wireless device 10-B and the wireless device 10-C Stability S_ {BC}, stability S_ {CX} of the link 11-CX connecting between the wireless device 10-C and the wireless device 10-X, connecting between the wireless device 10-D and the wireless device 10-X The stability S_ {DX} of the link 11-DX is as follows.
S_ {AB} = 1− (T _fail _ {AB} / T_ {AB}) (2)
S_ {AD} = 1− (T _fail _ {AD} / T_ {AD}) (3)
S_ {BX} = 1− (T _fail _ {BX} / T_ {BX}) (4)
S_ {BC} = 1- (T _fail _ {BC} / T_ {BC}) (5)
S_ {CX} = 1− (T _fail _ {CX} / T_ {CX}) (6)
S_ {DX} = 1- (T _fail _ {DX} / T_ {DX}) (7)

Next, the normalized link individual stability calculation unit 31 weights the link stability calculated by the link individual stability calculation unit 30 with the usage rate (number of transmissions) of the link, and normalizes the stability based on the usage rate. Is calculated (step S4 in FIG. 2). When normalizing the stability S_ {ij} of the link connecting the adjacent wireless device 10-i and the wireless device 10-j on the candidate route, the wireless device 10-i is connected only to the wireless device 10-j. The normalized stability S _{normal —} {ij} is as follows:
S _normal _ {ij} = S_ {ij} × (T_ {ij} / T_ {ij}) (8)

In addition, when the wireless device 10-i is connected to another wireless device 10-k in addition to the wireless device 10-j, the normalized stability S _normal _ {ij} is expressed by the following equation. .
S _{normal —} {ij} = S_ {ij} × [T_ {ij}
/ (T_ {ij} + T_ {ik})] (9)

  As shown in Expression (8) and Expression (9), the usage rate with the sum of the number of transmissions of all links connected to the wireless device 10-i as the denominator and the number of transmissions of the link to be normalized as a numerator The link stability S_ {ij} may be normalized by multiplying the link stability S_ {ij} to be normalized.

When evaluating the route between the wireless device 10-A and the wireless device 10-X shown in FIG. 3, normalized link stability _{Snormal_} {AB}, _{Snormal_} {AD}, _{Snormal_} {BX} , S _normal _ {BC}, S _normal _ {CX}, S _normal _ {DX} are as follows.
S _normal _ {AB} = S_ {AB} × [T_ {AB}
/ (T_ {AB} + T_ {AD})] (10)
S _normal _ {AD} = S_ {AD} × [T_ {AD}
/ (T_ {AD} + T_ {AB})] (11)
S _normal _ {BX} = S_ {BX} × [T_ {BX}
/ (T_ {BX} + T_ {BC})] (12)
S _normal _ {BC} = S_ {BC} × [T_ {BC}
/ (T_ {BC} + T_ {BX})] (13)
S _normal _ {CX} = S_ {CX} × (T_ {CX} / T_ {CX})
(14)
S _normal _ {DX} = S_ {DX} × (T_ {DX} / T_ {DX})
(15)

  Next, the path individual stability calculation unit 4 calculates the stability of each candidate path based on the link stability calculated by the normalized link individual stability calculation unit 31 (step S5 in FIG. 2). The stability of a candidate route is represented by the product of the stability of links connecting adjacent wireless devices on this candidate route.

When evaluating the route between the wireless device 10-A and the wireless device 10-X shown in FIG. 3, the stability S ^to _ {ABX of the route of the wireless device 10-A → the wireless device 10-B → the wireless device 10-X. }, the wireless device 10-a → wireless device 10-B → wireless device 10-C → stability ^S ~ _ {ABCX the path of the wireless device 10-X}, the wireless device 10-a → wireless device 10-D → wireless The stability S ^~ _ {ADX} of the path of the device 10-X is as follows.
^{S ~ _ {ABX} = S} normal _ {AB} × S normal _ {BX} ··· (16)
^{S ~ _ {ABCX} = S} normal _ {AB} × S normal _ {BC} × S normal _ {CX}
... (17)
S ^~ _ {ADX} = _{Snormal_} {AD} * _{Snormal_} {DX} (18)

Next, the total evaluation value calculation unit 5 calculates the total stability of the path between the wireless device 10-A and the wireless device 10-X (step S6 in FIG. 2). The total stability of the route between non-adjacent wireless devices is represented by the sum of the stability of a plurality of candidate routes that may be used as a route. The total stability S_ {AX} of the path between the wireless device 10-A and the wireless device 10-X is expressed by the following equation.
^{S_ {AX} = S ~ _} {ABX} + S ~ _ {ABCX} + S ~ _ {ADX}
... (19)

Note that, by normalizing the link stability in step S4, the total route stability is in the range of 0 to 1.0.
Finally, the determination unit 6 compares the total stability of the evaluation target route calculated by the total evaluation value calculation unit 5 with a preset threshold value, and the total stability of the evaluation target route is equal to or greater than the threshold value. In this case, it is determined that the communication state of the route to be evaluated is stable, and when the total stability of the route to be evaluated is lower than the threshold, it is determined that the communication state of the route to be evaluated is not stable (see FIG. 2 step S7). The determination unit 6 notifies the engineer by displaying the determination result on a screen, for example.

  As for the threshold value, for example, when evaluating the stability of the route after regular maintenance, the determination unit 6 may be set in advance using the stability of the route before the maintenance as a threshold value. Further, 0.95 times (95%) may be set as a threshold value based on the stability of the route before maintenance.

Next, an example in which it is determined that the communication state of the route is stable as a result of evaluating the route will be described. Here, as shown in FIG. 4, the number of transmissions T_ {AB} = 100 times between the wireless device 10-A and the wireless device 10-B, the number of failures T _{fail_} {AB} = 3 times, and the wireless device 10-A. And the number of transmissions T_ {AD} = 6 times, the number of failures T _{fail_} {AD} = 2 times, and the number of transmissions T_ {BX} = between the wireless devices 10-B and 10-X. 150 times, the number of failures T _{fail —} {BX} = 6 times, the number of transmissions T_ {BC} = 4 times between the wireless device 10-B and the wireless device 10-C, the number of failures T _{fail —} {BC} = 1 Number of transmissions T_ {CX} = 100 times between the wireless device 10-C and the wireless device 10-X, number of failures T _{fail_} {CX} = 4 times, number of transmissions between the wireless device 10-D and the wireless device 10-X It is assumed that T_ {DX} = 120 times and the number of failures T _{fail_} {DX} = 4 times.

At this time, the stability S_ {AB}, S_ {AD}, S_ {BX}, S_ {BC} of each link 11-AB, 11-AD, 11-BX, 11-BC, 11-CX, 11-DX , S_ {CX}, S_ {DX} are as follows.
S_ {AB} = 1− (3/100) = 0.970 (20)
S_ {AD} = 1− (2/6) = 0.667 (21)
S_ {BX} = 1− (6/150) = 0.960 (22)
S_ {BC} = 1- (1/4) = 0.750 (23)
S_ {CX} = 1− (4/100) = 0.960 (24)
S_ {DX} = 1- (4/120) = 0.967 (25)

Normalized link stability _{Snormal_} {AB}, _{Snormal_} {AD}, _{Snormal_} {BX}, _{Snormal_} {BC}, _{Snormal_} {CX}, _{Snormal_} {DX} are as follows: become that way.
S _{normal —} {AB} = 0.970 × [100 / (100 + 6)] (26)
S _{normal —} {AD} = 0.667 × [6 / (6 + 100)] (27)
S _{normal —} {BX} = 0.960 × [150 / (150 + 4)] (28)
S _{normal —} {BC} = 0.750 × [4 / (4 + 150)] (29)
S _{normal —} {CX} = 0.960 × (100/100) (30)
S _{normal —} {DX} = 0.967 × (120/120) (31)

Wireless device 10-A → wireless device 10-B → Stability ^S ~ _ {ABX} route that the wireless device 10-X, the wireless device 10-A → wireless device 10-B → wireless device 10-C → wireless device 10 stability ^S ~ _ {ABCX} route of -X, wireless device 10-a → wireless device 10-D → stability ^S ~ _ {ADX} route that the wireless device 10-X is as follows.
S ^~ _ {ABX} = 0.970 × 0.960 = 0.856 (32)
S ^~ _ {ABCX} = 0.970 × 0.750 × 0.960 = 0.177
... (33)
S ^~ _ {ADX} = 0.667 × 0.967 = 0.036 (34)

The total stability S_ {AX} of the path between the wireless device 10-A and the wireless device 10-X is as follows.
S_ {AX} = 0.856 + 0.017 + 0.036 = 0.909 (35)

  If the threshold value preset in the determination unit 6 is 0.90 (communication success rate 90%), for example, the total stability S_ {AX} = 0.909 of the route is equal to or greater than the threshold value 0.90. 6 determines that the communication state of the route is stable.

Next, an example will be described in which it is determined that the communication state of the route is not stable as a result of evaluating the route. Here, as shown in FIG. 5, the number of transmissions T_ {AB} = 90 times between the wireless device 10-A and the wireless device 10-B, the number of failures T _{fail_} {AB} = 2 times, and the wireless device 10-A. And the number of transmissions between the wireless device 10-D T_ {AD} = 16 times, the number of failures T _{fail_} {AD} = 6 times, the number of transmissions between the wireless device 10-B and the wireless device 10-X T_ {BX} = 150 times, the number of failures T _{fail —} {BX} = 6 times, the number of transmissions T_ {BC} = 4 times between the wireless device 10-B and the wireless device 10-C, the number of failures T _{fail —} {BC} = 1 Number of transmissions T_ {CX} = 100 times between the wireless device 10-C and the wireless device 10-X, number of failures T _{fail_} {CX} = 4 times, number of transmissions between the wireless device 10-D and the wireless device 10-X It is assumed that T_ {DX} = 120 times and the number of failures T _{fail_} {DX} = 4 times.

At this time, the stability S_ {AB}, S_ {AD}, S_ {BX}, S_ {BC} of each link 11-AB, 11-AD, 11-BX, 11-BC, 11-CX, 11-DX , S_ {CX}, S_ {DX} are as follows.
S_ {AB} = 1− (2/90) = 0.978 (36)
S_ {AD} = 1− (6/16) = 0.625 (37)
S_ {BX} = 1− (6/150) = 0.960 (38)
S_ {BC} = 1- (1/4) = 0.750 (39)
S_ {CX} = 1− (4/100) = 0.960 (40)
S_ {DX} = 1− (4/120) = 0.967 (41)

Normalized link stability _{Snormal_} {AB}, _{Snormal_} {AD}, _{Snormal_} {BX}, _{Snormal_} {BC}, _{Snormal_} {CX}, _{Snormal_} {DX} are as follows: become that way.
S _{normal —} {AB} = 0.978 × [90 / (90 + 16)] (42)
S _{normal —} {AD} = 0.625 × [16 / (16 + 90)] (43)
S _{normal —} {BX} = 0.960 × [150 / (150 + 4)] (44)
S _{normal —} {BC} = 0.750 × [4 / (4 + 150)] (45)
S _{normal —} {CX} = 0.960 × (100/100) (46)
S _{normal —} {DX} = 0.967 × (120/120) (47)

Wireless device 10-A → wireless device 10-B → Stability ^S ~ _ {ABX} route that the wireless device 10-X, the wireless device 10-A → wireless device 10-B → wireless device 10-C → wireless device 10 stability ^S ~ _ {ABCX} route of -X, wireless device 10-a → wireless device 10-D → stability ^S ~ _ {ADX} route that the wireless device 10-X is as follows.
S ^~ _ {ABX} = 0.978 × 0.960 = 0.76 (48)
S ^~ _ {ABCX} = 0.978 × 0.750 × 0.960 = 0.016
... (49)
S ^~ _ {ADX} = 0.625 × 0.967 = 0.091 (50)

The total stability S_ {AX} of the path between the wireless device 10-A and the wireless device 10-X is as follows.
S_ {AX} = 0.777 + 0.016 + 0.091 = 0.833 (51)

  If the threshold value preset in the determination unit 6 is 0.90 (communication success rate 90%), for example, the total stability S_ {AX} = 0.683 of the route is less than the threshold value 0.90. The unit 6 determines that the communication state of the route is not stable.

  As described above, in this embodiment, by calculating one index called the total stability of the route, an index for evaluating a plurality of candidate routes (paths) in total can be obtained. The possibility of overlooking serious problems can be reduced.

  When the stability of each candidate route is calculated individually, if the primary path performance is high, high numerical stability is calculated, but in many cases there are multiple candidate routes, in which case the connection status before and after maintenance There is a problem that it is difficult to make a superiority or inferiority evaluation. For example, although the stability of the primary path after maintenance is slightly deteriorated compared to before maintenance, it is difficult to judge superiority before and after maintenance when the stability of the secondary path is significantly improved. On the other hand, in the present embodiment, by obtaining an index for evaluating a plurality of candidate routes in total, unnecessary measures for stability degradation may be taken or necessary measures for stability degradation may be overlooked. Such problems can be alleviated.

  In this embodiment, the wireless communication state information is the number of transmissions and the number of failures between adjacent wireless devices, but is not limited to this, and the wireless communication state information is the number of transmissions between adjacent wireless devices. , And the number of successes indicating the number of replies (Ack) to transmission between adjacent wireless devices. In this case, instead of the transmission failure number acquisition unit 21 of the wireless communication state information acquisition unit 2, a transmission success number acquisition unit that acquires information on the number of successes between adjacent wireless devices on the candidate route may be provided. . Information on the number of successes can be obtained from a gateway conforming to ISA100.11a.

_Assuming that the number of successes between adjacent wireless devices 10-i and 10-j on the candidate route is T _safe _ {ij}, the link individual stability calculation unit 30 includes the wireless device 10-i and the wireless device 10-. What is necessary is just to calculate stability S_ {ij} of the link which connects between j like following Formula (FIG. 2 step S3).
S_ {ij} = T _safe _ {ij} / T_ {ij} (52)
The processing of steps S4 to S7 is as described above.

  The communication state evaluation apparatus described in the present embodiment can be realized by a computer including a CPU, a storage device, and an interface, and a program that controls these hardware resources. The CPU executes the processing described in the present embodiment in accordance with a program stored in the storage device.

  The present invention can be applied to a technique for evaluating a communication state of a route of a wireless network.

  DESCRIPTION OF SYMBOLS 1 ... Candidate path | route specific | specification part, 2 ... Wireless communication status information acquisition part, 3 ... Link stability calculation part, 4 ... Path | route separate stability calculation part, 5 ... Total evaluation value calculation part, 6 ... Determination part, 10 ... Wireless apparatus , 11 ... link, 20 ... transmission number acquisition unit, 21 ... transmission failure number acquisition unit, 30 ... link individual stability calculation unit, 31 ... normalized link individual stability calculation unit.

Claims (10)

Wireless communication state information acquisition means for acquiring wireless communication state information indicating a wireless communication state of a wireless device on a path to be evaluated in a wireless network;
Link individual stability calculation means for calculating the stability of a link connecting adjacent wireless devices on a plurality of candidate routes that may be used as the evaluation target route based on the wireless communication state information; ,
A normalized link individual stability calculation means for calculating the normalized stability by weighting the link stability calculated by the link individual stability calculation means by the usage rate of the link;
A path individual stability calculating means for calculating the stability of the plurality of candidate paths based on the normalized link stability;
A communication state evaluation apparatus for a wireless network, comprising: a total evaluation value calculation unit that calculates a total stability of the evaluation target route based on the stability of the plurality of candidate routes. Wireless communication state information acquisition means for acquiring wireless communication state information indicating a wireless communication state of a wireless device on a path to be evaluated in a wireless network;
Link individual stability calculation means for calculating the stability of a link connecting adjacent wireless devices on a plurality of candidate routes that may be used as the evaluation target route based on the wireless communication state information; ,
A path individual stability calculating means for calculating the stability of the plurality of candidate paths based on the stability of the link;
A total evaluation value calculating means for calculating a total stability of the evaluation target route based on the stability of the plurality of candidate routes;
And determining means for comparing the total stability of the route to be evaluated with a preset threshold value and determining whether or not the communication state of the route to be evaluated is stable. Wireless network communication state evaluation device. In the wireless network communication state evaluation apparatus according to claim 1 ,
Further, it comprises a determination means for comparing the total stability of the route to be evaluated with a preset threshold value and determining whether or not the communication state of the route to be evaluated is stable. A communication state evaluation device for a wireless network. In the wireless network communication state evaluation apparatus according to any one of claims 1 to 3,
The wireless network communication state evaluation apparatus further comprises candidate route specifying means for specifying the plurality of candidate routes and specifying a link connecting adjacent wireless devices on the candidate routes. In the wireless network communication state evaluation apparatus according to any one of claims 1 to 4,
The wireless communication state information includes the number of transmissions between adjacent wireless devices on the candidate route and the number of failures indicating the number of transmission replies between adjacent wireless devices, or the adjacent wireless devices on the candidate route. A wireless network communication state evaluation apparatus characterized in that the number of successful transmissions indicates the number of transmissions between the adjacent wireless devices and the number of replies to transmissions between adjacent wireless devices. A wireless communication state information acquisition step for acquiring wireless communication state information indicating a wireless communication state of a wireless device on a path to be evaluated in the wireless network;
A link individual stability calculating step for calculating the stability of a link connecting adjacent wireless devices on a plurality of candidate routes that may be used as the evaluation target route based on the wireless communication state information; ,
A normalized link individual stability calculating step for calculating the normalized stability by weighting the link stability calculated in the link individual stability calculating step by the usage rate of the link;
A path individual stability calculating step for calculating stability of the plurality of candidate paths based on the normalized link stability;
A wireless network communication state evaluation method, comprising: a total evaluation value calculation step of calculating a total stability of the evaluation target route based on the stability of the plurality of candidate routes. A wireless communication state information acquisition step for acquiring wireless communication state information indicating a wireless communication state of a wireless device on a path to be evaluated in the wireless network;
A link individual stability calculating step for calculating the stability of a link connecting adjacent wireless devices on a plurality of candidate routes that may be used as the evaluation target route based on the wireless communication state information; ,
A path individual stability calculating step for calculating the stability of the plurality of candidate paths based on the stability of the link;
A total evaluation value calculating step for calculating a total stability of the route to be evaluated based on the stability of the plurality of candidate routes;
A step of comparing the total stability of the route to be evaluated with a preset threshold value and determining whether or not the communication state of the route to be evaluated is stable. A wireless network communication state evaluation method. The wireless network communication state evaluation method according to claim 6 ,
Further, the method includes a determination step of determining whether or not a communication state of the evaluation target route is stable by comparing a total stability of the evaluation target route with a preset threshold value. To evaluate the communication state of a wireless network. In the wireless network communication state evaluation method according to any one of claims 6 to 8,
The wireless network communication state evaluation method further includes a candidate route specifying step of specifying the plurality of candidate routes and specifying a link connecting adjacent wireless devices on the candidate routes. The wireless network communication state evaluation method according to any one of claims 6 to 9,
The wireless communication state information includes the number of transmissions between adjacent wireless devices on the candidate route and the number of failures indicating the number of transmission replies between adjacent wireless devices, or the adjacent wireless devices on the candidate route. A communication state evaluation method for a wireless network, characterized in that the number of successful transmissions indicates the number of transmissions between the adjacent wireless devices and the number of transmission replies between adjacent wireless devices.

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