JP7542252B2 - Wireless communication device, wireless communication method, and wireless communication program - Google Patents

Description

Embodiments of the present invention relate to a wireless communication device, a wireless communication method, and a wireless communication program.

For example, at manufacturing sites, productivity is being improved by attaching sensors to tools and other equipment to collect information, or by operating AGVs (Automated Guided Vehicles) to transport parts. Because these tools and AGVs move in conjunction with the movement of people and goods, wireless communication is required for real-time information collection and operation.

In addition, in manufacturing sites, noise can be generated by the operation of machines, etc., which can have adverse effects such as causing errors in the data being transmitted, resulting in communication delays and other issues that make it impossible to meet the QoS (Quality of Service) requirements for wireless communication.

In response to circumstances in which the QoS requirements of wireless communication cannot be met, technologies such as those described in Patent Document 1, Patent Document 2, and Non-Patent Document 1 are provided.

Patent Document 1 discloses a technology that schedules multiple flows in an environment where multiple wireless communications coexist to prevent them from interfering with each other by allocating the time during which each flow can monopolize wireless resources according to its traffic volume.

Non-Patent Document 1 discloses a specification that checks whether other communications are taking place before starting communication, and puts communication on hold if radio waves with a signal strength above a certain level are being transmitted, thereby avoiding the effects of other communications and noise.

Patent document 2 discloses a technology that determines that radio waves whose received signal strength exceeds a threshold are noise, measures the time when noise occurs and the time when it does not occur, and, under the assumption that this repeats periodically, sets the communication rate so that communication delays can be met during communication when noise is not occurring.

JP 2019-118050 A JP 2018-019307 A

G. Bianchi, “Performance Analysis of the IEEE 802.11 Distributed Coordination Function,” IEEE Journal on Selected Areas in Communications, vol.18, no.3, pp.535-547, Mar. 2000.

Here, communications and noise at manufacturing sites have the following characteristics:
(1) Basically, there is no perfect periodicity in the occurrence of communication or noise. However, in manufacturing sites, multiple production processes are linked with each other, each with a cycle time. For this reason, it is possible to expect a certain degree of periodicity in the occurrence of communication and noise.
(2) In manufacturing sites, there is a mixture of noise that has a minor effect on wireless communication (such as inverter noise) and severe noise (such as wireless power supply).

The technology disclosed in Patent Document 1 makes it possible to schedule multiple controllable flows so that they do not interfere with each other. However, unlike communication, noise cannot be controlled, so it cannot be scheduled and has a negative impact. This means that QoS requirements cannot be met in environments where noise occurs.

The specifications disclosed in Non-Patent Document 1 can avoid interference when noise occurs. However, this is a sequential control that will not communicate if there is other communication or noise when you are trying to communicate. This means that QoS requirements cannot be met in a planned manner.

In addition, the technology disclosed in Patent Document 2, as shown in FIG. 7(a), sets the transmission waiting time W to be equal intervals and the same duration for noise N that occurs at equal intervals and for the same duration, thereby avoiding noise N and making it possible to communicate so as to satisfy, for example, communication delays. The period between the transmission waiting times W is set as the communication slot time T during which communication is possible. However, as described above, although noise in manufacturing sites has a certain degree of periodicity, the timing at which noise occurs and the duration for which noise continues are diverse. For this reason, as shown in FIG. 7(b), there is a situation in which interference periods I0 to I2 occur during the communication slot time T, during which noise N100 and N200 overlap, deteriorating QoS. There is also mild noise N300 that does not affect communication. Even if mild noise N300 occurs, communication will be stopped, resulting in wasted communication time and hindering improvement of communication efficiency.

Embodiments of the present invention provide a wireless communication device, a wireless communication method, and a wireless communication program that can systematically and efficiently meet good QoS requirements even in a wireless environment where communication interference factors occur.

A wireless communication device according to a first aspect of the present invention is a wireless communication device that performs data communication via a wireless network, and includes a transceiver unit having a transmitting device that transmits transmission data via the wireless network and a receiving device that receives received data, an error correction unit that performs encoding processing of the transmission data when transmitting data and decoding processing of the received data when receiving data, so that correctable errors including bit errors that occur in data during communication can be corrected without retransmitting the data, and a processing unit that detects periodically occurring noise based on at least one of the success or failure of data communication via the wireless network, including whether or not the error was corrected by the error correction unit, and the result of measuring the radio wave environment of the wireless network. and a transmission standby time setting unit that sets a time during which data transmitted to the wireless network will not arrive normally at a receiving device based on the noise generation pattern, and sets a transmission standby time during which the transmitting device of the transmitting/receiving unit waits to transmit the transmission data to the wireless network during the time during which the transmission data does not arrive normally . The noise estimation unit is configured to: (e) determine the number or percentage of the transmitted data that does not arrive normally at the receiving device; (f) determine the number or percentage of the received data that the transmitting/receiving unit is unable to receive normally; and (g) determine whether the signal strength observed in the measurement of the radio wave environment is greater than or equal to a predetermined value. (h) the number or percentage of times or percentages excluding times when the transceiver unit was transmitting or receiving data while the channel usage time observed in the measurement of the radio wave environment was equal to or greater than a predetermined threshold, the number or percentages being ... The method is characterized in that the first time period and the second time period are stored in consecutive cycles of a predetermined number or more, and when a time period stored as the first time period in a noise generation pattern in the consecutive cycles is stored as the second time period in a noise generation pattern in the certain cycle, the noise generation pattern is updated so that the time period is included in the second time period, and when a time period stored as the second time period in a noise generation pattern in the consecutive cycles is stored as the first time period in the noise generation pattern in the certain cycle, the noise generation pattern is updated so that the second time period is changed to the first time period at a predetermined time or rate so that the time period is gradually included in the first time period.

A wireless communication device according to a second aspect of the present invention is the wireless communication device of the first aspect, further comprising a mechanism in which the noise estimation unit controls the second time period in which the communication failure factor is estimated to have occurred in the noise occurrence pattern to converge to a certain timing and a certain duration.

A wireless communication device according to a third aspect of the present invention is a wireless communication device that performs data communication via a wireless network, and includes a transceiver unit having a transmitting device that transmits transmission data via the wireless network and a receiving device that receives received data, an error correction unit that performs encoding processing of the transmission data when transmitting data and decoding processing of the received data when receiving data, so that correctable errors including bit errors that occur in data during communication can be corrected without retransmitting the data, and a noise estimation unit that estimates a noise generation pattern including the occurrence timing of a communication interference element including periodically occurring noise and the duration of the communication interference element based on at least one of the success or failure of data communication via the wireless network including whether or not the error was corrected by the error correction unit and a result of measuring the radio wave environment of the wireless network, and a time period during which the transmission data will not normally arrive at a receiving device even if the data is transmitted to the wireless network based on the noise generation pattern, and a time period during which the transmission data will not normally arrive at the receiving device of the transceiver unit. and a transmission standby time setting unit that sets a transmission standby time for waiting transmission of data, wherein the noise estimation unit detects the occurrence of the communication failure element when (a) the number or percentage of the transmission data that does not arrive normally at the receiving device, (b) the number or percentage of the reception data that the transmission/reception unit is unable to receive normally, (c) the number or percentage of the number of times or percentages excluding the cases where the transmission/reception unit transmits/receives data while the signal strength observed in the measurement of the radio wave environment is equal to or greater than a predetermined threshold, and (d) at least one value of the time or percentages excluding the cases where the transmission/reception unit transmits/receives data while the channel usage time observed in the measurement of the radio wave environment is equal to or greater than a predetermined threshold is equal to or greater than a predetermined threshold, and stores the occurrence of the communication failure element or the value of the communication failure element as time-series information together with the time at which the communication failure element occurred, and further , divides a predetermined time interval into a period, and assumes that the same noise occurrence pattern is repeated in each period, and models the occurrence of the communication failure element based on the time-series information to estimate the noise occurrence pattern.

A wireless communication device according to a fourth aspect of the present invention is a wireless communication device that performs data communication via a wireless network, the device comprising: a transceiver unit having a transmitting device that transmits transmission data via the wireless network and a receiving device that receives received data; an error correction unit that performs encoding processing of the transmission data when transmitting data and decoding processing of the received data when receiving data, so that correctable errors including bit errors that occur in data during communication can be corrected without retransmitting the data; a noise estimation unit that estimates a noise generation pattern including the occurrence timing of a communication interference element including a periodically occurring noise and the duration of the communication interference element based on at least one of the success or failure of data communication via the wireless network including whether or not the error was corrected by the error correction unit and a result of measuring the radio wave environment of the wireless network; and a noise estimation unit that estimates a noise generation pattern including the occurrence timing of a communication interference element including a periodically occurring noise and the duration of the communication interference element based on the noise generation pattern. and a transmission standby time setting unit that sets a time period during which the transmission data will not normally arrive at the receiving side device even if the data is transmitted to the receiving side device, and sets a transmission standby time that causes the transmitting device of the transceiver unit to wait to transmit the transmission data to the wireless network during the time period during which the transmission data is not normally received, and further comprises a noise handling method determination unit that determines whether to cause the transmission standby time setting unit to set the estimated time period as the transmission standby time or to cause the error correction unit to increase the coding rate of error correction based on at least one of the following: (i) information on the intensity or frequency of the noise in the estimated time period; (j) a time width of the estimated time period; and (k) information related to wireless communication including a communication throughput and a data rate in a time period adjacent to the estimated time period or in the same time period in another cycle, for a time period during which the communication failure element is estimated to have occurred in the noise occurrence pattern estimated by the noise estimation unit .

A wireless communication system according to a fifth aspect of the present invention is a wireless communication system for performing data communication via a wireless network, and for a correctable error including a bit error occurring in data being communicated, encoding processing is performed on transmitted data during data transmission, and decoding processing is performed on received data during data reception, so that the error can be corrected without retransmitting the data, and a noise occurrence pattern including the occurrence timing of a communication interference element including a periodically occurring noise and the duration of the communication interference element is estimated based on at least one of the success or failure of data communication via the wireless network including whether or not the error was corrected and the result of measuring the radio wave environment of the wireless network, Based on the noise generation pattern, a time period during which data transmitted to the wireless network will not arrive normally at the receiving device is set, and during the time period during which the transmission data will not arrive normally, transmission of the transmission data from the transmitting device to the wireless network is put on hold , and in estimating the noise generation pattern, (e) the number or percentage of the transmission data that did not arrive normally at the receiving device, (f) the number or percentage of the reception data that the transmitting/receiving device was not able to receive normally, (g) the number or percentage of the number of times or percentage of the number of times that the transmitting/receiving device was transmitting/receiving data when the signal strength observed in the measurement of the radio wave environment was equal to or greater than a predetermined threshold, excluding the number of times or percentage of the number of times that the transmitting/receiving device was transmitting/receiving data when the signal strength observed in the measurement of the radio wave environment was equal to or greater than a predetermined threshold, and the occurrence of a communication interference factor is detected when at least one value of a time or a ratio excluding a time when the transmitting/receiving device is transmitting/receiving data is equal to or greater than a predetermined threshold value while a channel usage time observed during the period is equal to or greater than a predetermined threshold value, the method divides predetermined time intervals into periods, and for the divided periods, stores a first time period during which the communication interference factor is estimated not to have occurred in a certain period within the divided periods in a noise generation pattern of the certain period and a second time period during which the communication interference factor is estimated to have occurred, and stores these The noise generation pattern is updated so that a first time period and the second time period are stored, and when, among the time periods stored as the first time period in the noise generation pattern in the continuous cycle, a time period is stored as the second time period in the noise generation pattern in the certain cycle, the noise generation pattern is updated so that the time period is included in the second time period, and when, among the time periods stored as the second time period in the noise generation pattern in the continuous cycle, a time period is stored as the first time period in the noise generation pattern in the certain cycle, the noise generation pattern is updated so that the second time period is changed to the first time period at a predetermined time or rate so that the time period is gradually included in the first time period .
A wireless communication method according to a sixth aspect of the present invention includes: encoding transmission data during data transmission, and decoding received data during data reception, so that correctable errors including bit errors occurring in data being communicated can be corrected without retransmitting the data; estimating a noise generation pattern including occurrence timing of a communication interference element including periodically occurring noise and duration of the communication interference element based on at least one of the success or failure of data communication via the wireless network including whether the error was corrected and a result of measuring the radio wave environment of the wireless network; setting a time during which the transmission data will not normally arrive at a receiving device even if data is transmitted to the wireless network based on the noise generation pattern; and causing the transmitting device to suspend transmission of the transmission data to the wireless network during the time during which the transmission data will not normally arrive; and estimating the noise generation pattern by: (a) determining whether or not the transmission data has correctly arrived at the receiving device among the transmission data; (b) the number or percentage of the received data that the transmitter/receiver was unable to receive normally; (c) the number or percentage of the number of times or percentages, excluding the cases when the transmitter/receiver was transmitting/receiving data, when the signal strength observed in the measurement of the radio wave environment was equal to or above a predetermined threshold; (d) the occurrence of a communication failure element is detected when at least one value of the time or percentages, excluding the cases when the transmitter/receiver was transmitting/receiving data, is equal to or above a predetermined threshold, when the channel usage time observed in the measurement of the radio wave environment was equal to or above a predetermined threshold, and the occurrence of the communication failure element or the value of the communication failure element is stored as time series information together with the time when the communication failure element occurred; and further, a predetermined time interval is divided into periods, and the noise generation pattern is assumed to be repeated in each period, and the occurrence of the communication failure element is modeled based on the time series information to estimate the noise generation pattern.

A wireless communication program according to a seventh aspect of the present invention is a wireless communication program for performing data communication via a wireless network, the wireless communication method for performing data communication via a wireless network, the wireless communication program comprising the steps of: encoding transmission data during data transmission, and decoding received data during data reception, so that correctable errors including bit errors occurring in data during communication can be corrected without retransmitting the data; and detecting timing of occurrence of communication interference factors including periodically occurring noise and occurrence of the communication interference factors based on at least one of the results of measurement of the success or failure of data communication via the wireless network, including whether or not the errors could be corrected, and the radio wave environment of the wireless network. and a step of setting a time during which data transmitted to the wireless network will not arrive normally at a receiving device based on the noise generation pattern, and suspending transmission of the transmission data to the wireless network during the time during which the transmission data will not arrive normally . The step of estimating the noise generation pattern includes: (e) determining the number or percentage of the transmission data that did not arrive normally at the receiving device; (f) determining the number or percentage of the reception data that could not be received normally by the transmitting/receiving device; and (g) determining the number or percentage of the reception data that could not be received normally by the transmitting/receiving device, except when the transmitting/receiving device was transmitting/receiving data while the signal strength observed in the measurement of the radio wave environment was equal to or greater than a predetermined threshold. (h) detecting the occurrence of a communication interference factor when at least one value of the time or percentage excluding the time when the transmission/reception device is transmitting/receiving data is equal to or greater than a predetermined threshold while the channel usage time observed in the measurement of the radio wave environment is equal to or greater than a predetermined threshold, dividing a predetermined time interval into periods, and for the divided periods, storing a first time period during which the communication interference factor is estimated not to have occurred in a certain period within the divided periods in the noise generation pattern of the certain period and a second time period during which the communication interference factor is estimated to have occurred, and detecting the occurrence of a communication interference factor in a certain number of consecutive periods other than the certain period within the divided periods and updating the noise generation pattern so that, when a time period stored as the first time period in the noise generation pattern in the continuous cycle is stored as the second time period in the noise generation pattern in the certain cycle, the noise generation pattern is updated so that the time period is included in the second time period; and when a time period stored as the second time period in the noise generation pattern in the continuous cycle is stored as the first time period in the noise generation pattern in the certain cycle, the noise generation pattern is updated so that the second time period is changed to the first time period at a predetermined time or rate so that the time period is gradually included in the first time period .
A wireless communication program according to an eighth aspect of the present invention is a program for communicating data via a wireless network.
a step of encoding transmission data during data transmission and decoding received data during data reception so that correctable errors, including bit errors, occurring in data being communicated can be corrected without retransmitting the data; a step of estimating a noise generation pattern including occurrence timing of a communication interference element, including noise that occurs periodically, and a duration of the communication interference element, based on at least one of a result of measuring a radio wave environment of the wireless network and a result of success or failure of data communication via the wireless network, including whether or not the error was corrected; and a step of setting a time during which the transmission data will not normally arrive at a receiving device even if the data is transmitted to the wireless network, based on the noise generation pattern, and causing the transmitting device to suspend transmission of the transmission data to the wireless network during the time during which the transmission data will not normally arrive. The step of estimating the noise generation pattern includes the steps of: (a) determining whether or not the reception (b) the number or percentage of the received data that the transmitting/receiving unit was unable to receive normally from the side device; (c) the number or percentage of the number of times or percentages excluding the cases where the transmitting/receiving unit was transmitting/receiving data while the signal strength observed in the measurement of the radio wave environment was equal to or greater than a predetermined threshold; (d) the occurrence of a communication failure element when at least one value of the time or percentages excluding the cases where the transmitting/receiving unit was transmitting/receiving data while the channel usage time observed in the measurement of the radio wave environment was equal to or greater than a predetermined threshold is equal to or greater than a predetermined threshold, and the occurrence of the communication failure element or the value of the communication failure element is stored as time-series information together with the time at which the communication failure element occurred; and further comprising a step of dividing a predetermined time interval into a period, assuming that the same noise generation pattern is repeated in each period, and modeling the occurrence of the communication failure element based on the time-series information to estimate the noise generation pattern.

According to the first to eighth aspects of the present invention, it is possible to provide a wireless communication device, a wireless communication method, and a wireless communication program that can systematically and efficiently satisfy good QoS requirements even in a wireless environment where communication interference factors occur.

FIG. 1 is a schematic block diagram showing an example of a basic configuration of a wireless communication system capable of implementing a wireless communication method according to the first embodiment. FIG. 2 is a schematic diagram showing an example of an image of a manufacturing site to which the wireless communication system according to the first embodiment is applied. FIG. 3 is a flowchart showing an example of a wireless communication method according to the first embodiment. FIG. 4 is a time chart showing an example of data communication by the wireless communication method according to the first embodiment. 5(a) to 5(c) are time charts showing another example of data communication by the wireless communication method according to the first embodiment. FIG. 11 is a schematic block diagram showing an example of a basic configuration of a wireless communication system capable of executing a wireless communication method according to a second embodiment. 7(a) and 7(b) are time charts showing the problem that the invention is to solve.

Below, some embodiments of the present invention will be described with reference to the drawings. In each drawing, common parts are given common reference symbols, and duplicated explanations will be omitted.

First Embodiment
Fig. 1 is a schematic block diagram showing an example of a basic configuration of a wireless communication system capable of executing a wireless communication system (wireless communication method) according to a first embodiment. Fig. 2 is a schematic diagram showing an example of an image of a manufacturing site to which the wireless communication system according to the first embodiment is applied.

<Wireless communication system 100>
As shown in Fig. 1, a wireless communication system 100 capable of executing a wireless communication method according to the first embodiment is configured to include a plurality of wireless communication devices that perform data communication via a wireless network 3. Fig. 1 shows one first wireless communication device 1 and one second wireless communication device 2 as a basic example. Note that there may be a plurality of first wireless communication devices 1 and a plurality of second wireless communication devices 2.

The first wireless communication device 1 is incorporated as hardware into a transmitting device 51, for example. If the environment to which the wireless communication system 100 is applied is a manufacturing site, examples of the transmitting device 51 include a production tool (manufacturing tool, manufacturing device, etc.) 51a, a robot 51b, an automatic guided vehicle (AGV: Automatic Guided Vehicle) 51c, an inspection device 51d, and a surveillance camera (imaging device) 51e, as shown in FIG. 2.

The second wireless communication device 2 is incorporated, for example, as hardware into the receiving device 52. An example of the receiving device 52 is an access point (AP) device 52a at a manufacturing site, as shown in FIG. 2.

When the transmitting device 51 includes a wireless communication device (an existing wireless communication device), the first wireless communication device 1 can incorporate the wireless communication flow executed by the first wireless communication device 1 into the transmitting device 51 as software (a wireless communication computer program). The same applies to the second wireless communication device 2. In these cases, the existing wireless communication device operates as a wireless communication device similar to the first wireless communication device 1 or the second wireless communication device 2.

Thus, the first embodiment of the invention can be implemented in both hardware and software, but the embodiment will be described assuming it is implemented primarily in hardware.

<First Wireless Communication Device 1>
As shown in FIG. 1, the first wireless communication device 1 includes a first transceiver unit 11 , a first error correction unit 12 , a noise estimation unit 13 , a transmission standby time setting unit 14 and a first communication control unit 15 .

The first transceiver 11 transmits and receives data wirelessly.

When data is transmitted, the first error correction unit 12 performs, for example, encoding processing of the transmitted data in the transmitting device of the first transmission/reception unit 11, so that correctable errors such as bit errors that occur in data during communication can be corrected without retransmitting the data, and when data is received, the first error correction unit 12 performs, for example, decoding processing of the received data in the receiving device of the first transmission/reception unit 11.

The noise estimation unit 13 estimates a noise occurrence pattern based on at least one of the communication results of data communication via the wireless network 3, including whether the first error correction unit 12 was able to correct the above error, and the result of measuring the radio wave environment of the wireless network 3. The noise occurrence pattern includes, for example, the occurrence timing of a periodically occurring communication interference element and the duration of the communication interference element. An example of a communication interference element is noise, and the communication interference element includes at least noise. In this specification, the "communication interference element" is abbreviated as noise, etc. as necessary. Here, if the first error correction unit 12 was able to correct a bit error, etc., the noise estimation unit 13 determines that the data has arrived normally at the transmitting device 51 or that the transmitting device 51 has been able to receive the data normally, and excludes it from detection of noise, etc.

The noise estimation unit 13 according to this embodiment, for example,
(a) the number or percentage of transmitted data that did not reach the receiving device 52 normally, (b) the number or percentage of received data that the first transmitting/receiving unit 11 could not normally receive, (c) the number or percentage excluding the case where the first transmitting/receiving unit 11 transmitted/received data when the signal strength observed in the measurement of the radio wave environment was equal to or greater than a predetermined threshold, (d) the occurrence of a communication failure element is detected when at least one value of the time or percentage excluding the case where the first transmitting/receiving unit 11 transmitted/received data when the channel usage time observed in the measurement of the radio wave environment was equal to or greater than a predetermined threshold is equal to or greater than a predetermined threshold. Furthermore, the noise estimation unit 13 stores the occurrence of the communication failure element or the value of the communication failure element together with the time when the communication failure element occurred as time-series information, and estimates a noise occurrence pattern by modeling the occurrence of the communication failure element based on this time-series information.

Furthermore, the noise estimation unit 13 according to this embodiment can be configured to estimate a noise generation pattern by modeling the occurrence of communication failure factors based on the time series information, for example, on the premise that the same noise generation pattern is repeated for each of the divided periods, with a predetermined time interval being divided into periods.
At least one of the following methods should be used: - Estimating noise, etc. that occurs at the same time period every cycle as a noise occurrence pattern; - Estimating a noise occurrence pattern by statistically overlaying time series information on the occurrence of noise, etc. every cycle or the values of noise, etc.

The transmission standby time setting unit 14 sets a time (transmission standby time) during which the transmission data does not normally arrive at the receiving device of the receiving device 52 due to the influence of noise, etc., based on the noise occurrence pattern estimated by the noise estimation unit 13. Then, the transmission standby time setting unit 14 causes the data transmitting/receiving unit of the transmitting device 51 to wait for the transmission of data to the wireless network during the transmission standby time.

The first communication control unit 15 controls the transmission and reception of data in the first transceiver unit 11. During data transmission, the first communication control unit 15 causes data transmission from the first wireless communication device 1 to the second wireless communication device 2 to wait during a transmission standby time. Then, data transmission from the first wireless communication device 1 to the second wireless communication device 2 is executed during a communication slot time during which data can be transmitted, which is set outside the transmission standby time.

<Second Wireless Communication Device 2>
As shown in FIG. 1 , the second wireless communication device 2 includes a second transceiver unit 21 , a second error correction unit 22 , and a second communication control unit 25 .

The second transceiver 21 transmits and receives data wirelessly.

The second error correction unit 22, like the first error correction unit 12, performs encoding processing when transmitting data and decoding processing when receiving data so that the above-mentioned bit errors, etc. can be corrected.

The second communication control unit 25 controls the transmission and reception of data in the second transceiver unit 21.

<Wireless communication flow (wireless communication method)>
Fig. 3 is a flowchart showing an example of the wireless communication method according to the first embodiment. Fig. 4 is a time chart showing an example of data communication by the wireless communication method according to the first embodiment.

<<Estimation of occurrence patterns of communication failure factors>>
3, an occurrence pattern of communication interference factors such as noise that occur periodically in the wireless network 3 is estimated. The occurrence pattern of communication interference factors such as noise is based on at least one of the communication results of data communication via the wireless network 3 and the measurement results of measuring the radio wave environment of the wireless network 3. These communication results and/or measurement results can be obtained by, for example, actually transmitting and receiving data using the first transceiver 11.

Here, the communication interference elements include, for example, elements that occur in conjunction with the takt time set in the wireless usage environment. An example of a wireless usage environment is the manufacturing site shown in FIG. 2. For example, at a manufacturing site, multiple production processes are linked to each other with a cycle of the takt time. For this reason, a certain degree of periodicity can be expected in the occurrence of noise, etc. In the wireless communication method according to the first embodiment, for example, attention is focused on communication interference elements that occur in conjunction with the takt time, and a search is performed to determine whether or not there is periodicity in the occurrence timing and duration of this communication interference element. The noise estimation unit 13 estimates a pattern (noise occurrence pattern) of the timing at which the communication interference element occurs, the duration for which the communication interference element continues, etc.

<<Exclusion of minor communication disruption factors>>
Next, as shown in step ST2 in FIG. 3, minor communication interference elements are excluded from the noise generation pattern. In the first embodiment, minor communication interference elements refer to, for example, elements that can be recovered by error correction in the first error correction unit 12 and the second error correction unit 22, elements that do not affect communication, and the like. An example of a minor communication interference element is inverter noise, etc. In this way, minor communication interference elements are excluded from the noise generation pattern, and transmission is put on hold when a major communication interference element occurs. This makes it possible to eliminate waste of wireless resources and improve communication efficiency.

<<Setting the transmission standby time>>
Next, as shown in step ST3 in FIG. 3, transmission standby times W0 to W1 for waiting data transmission are set based on the estimated noise generation pattern. The transmission standby times W0 to W1 are not set at equal intervals, but are set flexibly according to the timing of occurrence of noises N0 to N2 and the like and the duration of the noises, as shown in FIG. 4. This makes it possible to reduce the occurrence of communication interference caused by noises N0 to N2 and the like, compared to the case where the transmission standby times W0 to W1 are set at equal intervals. This makes it possible to systematically and efficiently satisfy good QoS requirements even in a wireless environment where communication interference factors occur. The transmission standby times are set in the transmission standby time setting unit 14.

<<Setting the communication slot time>>
Next, as shown in step ST4 in Fig. 3, communication slot times T0 to T2 during which data can be transmitted are set to the time excluding the transmission standby times W0 to W1. The communication slot times T0 to T2 are set, for example, sequentially after the transmission standby times W0 to W1. The communication slot times T0 to T2 can also be set, for example, by detecting the end of the transmission standby times W0 to W1 and the start of the transmission standby times W0 to W1, respectively.

<<Transmitting data>>
In steps ST1 to ST4, the transmission standby times W0 to W1 and the communication slot times T0 to T2 are set in the transmitting device 51. Thereafter, as shown in step ST5 in FIG. 3, data transmission may be performed in accordance with the set transmission standby times W0 to W1 and communication slot times T0 to T2. The transmission data TD is transmitted from the transmitting device 51 to the first transmitting/receiving unit 11 via the first error correction unit 12, for example, and is transmitted from the first transmitting/receiving unit 11 to the wireless network 3. The second transmitting/receiving unit 21 receives the transmission data TD as reception data RD. Such data communication is repeated until the necessary communication is completed.

According to such a first embodiment, for example,
(1) In a wireless environment where communication interference factors occur, if it is possible to expect a certain degree of periodicity in the occurrence of communication interference factors, a pattern such as the timing at which the communication interference factors occur and the duration for which the communication interference factors continue is estimated. A transmission standby time is flexibly set according to this estimated pattern. Therefore, even in a wireless environment where communication interference factors occur, good QoS requirements can be systematically and efficiently satisfied.
(2) Minor communication failure factors are excluded, and when a serious communication failure factor occurs, transmission is put on hold. In other words, when a minor communication failure factor occurs, communication is continued. Therefore, it is possible to eliminate waste of wireless resources and improve communication efficiency.
The following advantages can be obtained.

<Other examples of data communication>
5(a) to 5(c) are time charts showing another example of data communication by the wireless communication method according to the first embodiment.
As described above, the noise estimation unit 13 according to this embodiment
(e) the number or percentage of transmitted data that did not reach the receiving device 52 normally; (f) the number or percentage of received data that could not be received normally by the first transceiver unit 11; (g) the number or percentage excluding the cases where the first transceiver unit 11 was transmitting or receiving data when the signal strength observed in the measurement of the radio wave environment was above a predetermined threshold; (h) the occurrence of a communication failure element is detected when at least one value of the time or percentage excluding the cases where the first transceiver unit 11 was transmitting or receiving data when the channel usage time observed in the measurement of the radio wave environment was above a predetermined threshold is above a predetermined threshold.

The noise estimation unit 13 according to this embodiment divides a predetermined time interval, for example, takt time 0 to takt time 4, into periods. For these divided periods, as shown in FIG. 5A, the noise estimation unit 13 stores a time period (first time period: communication slot time T) in which it is estimated that a communication failure element does not occur in the noise occurrence pattern at takt time 2, and a time period (second time period: transmission standby time W) in which it is estimated that a communication failure element occurs, in a certain period, for example, takt time 2, and in a noise occurrence pattern at takt time 2. Similarly, the noise estimation unit 13 stores a time period (first time period: communication slot time T) in which it is estimated that a communication failure element does not occur in the noise occurrence pattern at a predetermined number of consecutive periods other than takt time 2, for example, takt time 0, takt time 1, takt time 3, takt time 4, and in which it is estimated that a communication failure element occurs, in which it is estimated that a communication failure element occurs.

Next, as shown in FIG. 5(b), in the noise generation pattern at takt times 0 and 1, and at takt times 3 and 4 that occur consecutively a predetermined number of times (assuming the number is "2" in this example) or more among takt times 0 to takt times 4, it is estimated that no communication failure element has occurred, and if the noise generation pattern at a certain cycle among the time periods stored as the first time period (T) is stored as the second time period (W), the noise generation pattern is updated so that the time period is included in the second time period (W). In this way, the transmission waiting time Wa is added to the above time periods (communication slot time T) of takt times 0 and 1, and takt times 3 and 4.

Furthermore, as shown in FIG. 5(c), in the noise generation pattern at takt time 2, it is estimated that a communication failure has occurred, and among the time periods (W) stored as the second time period, in the noise generation pattern at takt time 0 and takt time 1, and at takt time 3 and takt time 4, it is estimated that a communication failure element has occurred, and among the noise generation patterns at takt time 0 and takt time 1, and at takt time 3 and takt time 4, among the noise generation patterns stored as the first time period, the noise generation pattern is updated so that the second time period (W) is changed to the first time period (T) at a predetermined time or rate so that the time period is gradually included in the first time period (T). In the example shown in FIG. 5(c), an example is shown in which the time period is reduced at a predetermined time or rate. Note that, as shown in FIG. 5(c), the transmission waiting time Wa at takt time 0 and takt time 1, and at takt time 3 and takt time 4 may be updated in accordance with the update of the second time period (W) at takt time 2.

The noise estimation unit 13 can also set the transmission standby time, for example, as shown in Figures 5(a) to 5(c). Such a noise estimation unit 13 can further include a mechanism for controlling the time period W (second time period and third time period) in which a communication failure element is estimated to have occurred in the noise occurrence pattern to converge to a certain timing and a certain duration. This mechanism can take into account hysteresis in noise, etc., and use a classical control method such as PID control, for example.

<Modifications of Wireless Communication Device>
Moreover, the first wireless communication device 1 may further include, for example, a noise handling method determination unit.

The noise handling method determination unit determines, for a time period in which a communication failure factor is estimated to have occurred in the noise occurrence pattern estimated by the noise estimation unit 13,
Based on at least one of (i) information on the intensity or frequency of noise in the estimated time period, (j) the duration of the estimated time period, and (k) information related to wireless communication including communication throughput and data rate in a time period adjacent to the estimated time period or in the same time period in another cycle, the transmission standby time setting unit 14 determines whether to set the estimated time period as a transmission standby time or to cause the error correction unit 12 to increase the error correction coding rate.

Second Embodiment
FIG. 6 is a schematic block diagram showing an example of a basic configuration of a wireless communication system capable of implementing a wireless communication scheme (wireless communication method) according to the second embodiment.

Depending on the wireless usage environment, a severe communication failure factor may suddenly occur in the wireless network 3. The second embodiment relates to a wireless communication method, a wireless communication system, and a wireless communication program that can maintain good QoS even when a severe communication failure factor suddenly occurs.

As shown in FIG. 6, wireless communication system 100b differs from wireless communication system 100 in that it further includes a severe noise detection unit 71.

The severe noise detection unit 71 detects sudden severe communication interference elements that occur suddenly in the wireless network 3. The severe noise detection unit 71 puts data transmission from the first wireless communication device 1 to the second wireless communication device 2 (omitted in FIG. 6) on hold while a severe communication interference element is occurring.

The wireless communication system 100b further includes a severe noise detection unit 71, so that if a severe communication interference element occurs suddenly, data transmission is forcibly put on hold. Therefore, even if a severe communication interference element occurs suddenly, good QoS can be maintained.

As shown in FIG. 6, the severe noise detection unit 71 may be provided in the transmitting device 51 or in the receiving device 52. It may also be provided in both the transmitting device 51 and the receiving device 52. Furthermore, in addition to the transmitting device 51 and the receiving device 52, the severe noise detection device may be provided separately in the wireless communication system 100b.

The method of determining whether the severe noise detection unit 71 has detected severe noise is as follows:
(l) Detect that a frame transmission error has occurred.
(m) Detects the occurrence of a bit error or the like in a received frame.
(n) Providing a sensor to detect severe noise

In the case of (l), the severe noise detector 71 can be provided in the transmitting device 51, for example.
In the case of (m), the severe noise detector 71 can be provided in the receiving device 52, for example.
In the case of (n), the severe noise detection unit 71 may be provided in the transmitting device 51 and/or the receiving device 52. Alternatively, the severe noise detection unit 71 may be provided separately from the transmitting device 51 and the receiving device 52 in the wireless communication system 100b.

In addition to the advantages of the first embodiment, the second embodiment can maintain good QoS even if, for example, a severe communication failure factor suddenly occurs in the wireless network 3.

Furthermore, various omissions, substitutions, and modifications are possible in the embodiment of the present invention without departing from the gist of the present invention. For example, the transmission standby time setting unit 14 that sets the transmission standby time does not necessarily need to be provided in the transmitting device 51. The transmission standby time setting unit 14 can also be provided in the receiving device 52. When the transmission standby time setting unit 14 is provided in the receiving device 52, for example, CTS (Clear To Send) can be used to allow the transmitting device 51 to transmit. The transmission standby time setting unit 14 can also be provided in an external device such as a communication control server. For example, such new forms and modifications are included in the scope and gist of the present invention, and are included in the scope of the invention described in the claims and the equivalents of the invention described in the claims.

100: Wireless communication system 100b: Wireless communication system 1: First wireless communication device 11: First transceiver unit 12: First error correction unit 13: Noise estimation unit 14: Transmission standby time setting unit 2: Second wireless communication device 21: Second transceiver unit 22: Second error correction unit
3: Wireless network 51: Transmitting device 51a: Production tool 51b: Robot 51c: Automatic guided vehicle 51d: Inspection device 51e: Surveillance camera 52: Receiving device 52a: Access point (AP) device 70: Severe noise detection unit N: Noise N100: Noise N200: Noise N300: Noise N0 to N2: Noise W: Transmission standby time W0 to W1: Transmission standby time Wa: Transmission standby time T: Communication slot time T0 to T2: Communication slot time I0 to I2: Interference period TD: Transmission data RD: Received data

Claims (8)

A wireless communication device that performs data communication via a wireless network,
a transceiver unit having a transmitting device for transmitting transmission data via the wireless network and a receiving device for receiving reception data;
an error correction unit that performs encoding processing of the transmission data during data transmission and performs decoding processing of the reception data during data reception, so that correctable errors, including bit errors, occurring in data during communication can be corrected without retransmitting the data;
a noise estimation unit that estimates a noise occurrence pattern including occurrence timing of a communication interference factor including a periodically occurring noise and a duration of the communication interference factor based on at least one of a result of measurement of a radio wave environment of the wireless network and a result of success or failure of data communication via the wireless network, including whether the error has been corrected by the error correction unit;
a transmission standby time setting unit that sets a time period during which data transmitted to the wireless network will not normally arrive at a receiving device based on the noise generation pattern, and sets a transmission standby time for causing the transmitting device of the transceiver unit to wait for transmission of the transmission data to the wireless network during the time period during which the transmission data will not normally arrive;
Equipped with
The noise estimation unit
(e) The number or percentage of the transmitted data that did not arrive normally at the receiving device.
(f) the number or percentage of the received data that the transmitting/receiving unit was not able to receive normally
(g) the number or percentage of times when the signal strength observed in the measurement of the radio wave environment was equal to or greater than a predetermined threshold, excluding the cases in which the transceiver unit was transmitting or receiving data;
(h) the time or percentage excluding the time when the transceiver unit was transmitting/receiving data during the channel usage time observed in the measurement of the radio wave environment that was equal to or greater than a predetermined threshold value;
When at least one of the values is equal to or greater than a predetermined threshold, it is detected that the communication failure factor has occurred;
A predetermined time interval is divided into periods, and for each period,
storing a first time period during a certain period among the divided periods during which the communication interference factor is estimated not to have occurred in a noise occurrence pattern during the certain period, and a second time period during which the communication interference factor is estimated to have occurred;
storing the first time zone and the second time zone in consecutive periods other than the certain period that are a predetermined number of times or more among the divided periods;
When a time period stored as the first time period in the noise occurrence pattern in the continuous cycle is stored as the second time period in the noise occurrence pattern in the certain cycle, the noise occurrence pattern is updated so that the time period is included in the second time period;
When a time period stored as the second time period in the noise generation pattern in the continuous cycle is stored as the first time period in the noise generation pattern in the certain cycle, the noise generation pattern is updated so as to change the second time period to the first time period at a predetermined time or rate so that the time period is gradually included in the first time period.
A wireless communication device comprising: The noise estimation unit is
The wireless communication device according to claim 1 , further comprising a mechanism for controlling the second time period in which the communication interference factor is estimated to have occurred in the noise occurrence pattern to converge to a certain timing and a certain duration. A wireless communication device that performs data communication via a wireless network,
a transceiver unit having a transmitting device for transmitting transmission data via the wireless network and a receiving device for receiving reception data;
an error correction unit that performs encoding processing of the transmission data during data transmission and performs decoding processing of the reception data during data reception, so that correctable errors, including bit errors, occurring in data during communication can be corrected without retransmitting the data;
a noise estimation unit that estimates a noise occurrence pattern including occurrence timing of a communication interference factor including a periodically occurring noise and a duration of the communication interference factor based on at least one of a result of measurement of a radio wave environment of the wireless network and a result of success or failure of data communication via the wireless network, including whether the error has been corrected by the error correction unit;
a transmission standby time setting unit that sets a time period during which data transmitted to the wireless network will not normally arrive at a receiving device based on the noise generation pattern, and sets a transmission standby time for causing the transmitting device of the transceiver unit to wait for transmission of the transmission data to the wireless network during the time period during which the transmission data will not normally arrive;
Equipped with
The noise estimation unit is
(a) The number or percentage of the transmitted data that did not arrive at the receiving device normally.
(b) the number or percentage of the received data that the transmitting/receiving unit was not able to receive normally;
(c) The number or percentage of times when the signal strength observed in the measurement of the radio wave environment was equal to or greater than a predetermined threshold, excluding the cases when the transceiver unit was transmitting or receiving data.
(d) A time or a ratio excluding a time when the transceiver unit is transmitting or receiving data during a channel usage time observed in the measurement of the radio wave environment that is equal to or greater than a predetermined threshold.
When at least one of the values is equal to or greater than a predetermined threshold, it is detected that the communication failure factor has occurred;
storing the occurrence of the communication failure element or the value of the communication failure element as time-series information together with the time when the communication failure element occurred;
moreover,
A predetermined time interval is divided into periods, and the same noise occurrence pattern is repeated for each period, and based on the time-series information, the occurrence of the communication failure factor is modeled to estimate the noise occurrence pattern.
A wireless communication device comprising: A wireless communication device that performs data communication via a wireless network,
a transceiver unit having a transmitting device for transmitting transmission data via the wireless network and a receiving device for receiving reception data;
an error correction unit that performs encoding processing of the transmission data during data transmission and performs decoding processing of the reception data during data reception, so that correctable errors, including bit errors, occurring in data during communication can be corrected without retransmitting the data;
a noise estimation unit that estimates a noise occurrence pattern including occurrence timing of a communication interference factor including a periodically occurring noise and a duration of the communication interference factor based on at least one of a result of measurement of a radio wave environment of the wireless network and a result of success or failure of data communication via the wireless network, including whether the error has been corrected by the error correction unit;
a transmission standby time setting unit that sets a time period during which data transmitted to the wireless network will not normally arrive at a receiving device based on the noise generation pattern, and sets a transmission standby time for causing the transmitting device of the transceiver unit to wait for transmission of the transmission data to the wireless network during the time period during which the transmission data will not normally arrive;
Equipped with
In the noise occurrence pattern estimated by the noise estimation unit,
For the time period during which the element is estimated to have occurred,
(i) information on the intensity or frequency of the noise during the estimated time period;
(j) the duration of the estimated time period
(k) information relating to wireless communication including communication throughput and data rate in a time period adjacent to the estimated time period or in the same time period in another cycle;
Based on at least one of the following:
a noise handling method determining unit for determining whether to set the estimated time period to the transmission standby time setting unit or to increase the coding rate of error correction in the error correction unit;
Further,
A wireless communication device comprising: A wireless communication method for performing data communication via a wireless network,
In order to correct correctable errors, including bit errors, that occur in data during communication, without the need to resend the data, a transmission data encoding process is performed in data transmission, and a reception data decoding process is performed in data reception;
estimating a noise occurrence pattern including occurrence timing of a communication interference element including a periodically occurring noise and a duration of the communication interference element based on at least one of the results of measurement of the radio wave environment of the wireless network and the success or failure of the data communication via the wireless network, including whether the error was corrected;
a time period during which data transmitted to the wireless network will not arrive normally at the receiving device based on the noise generation pattern, and during the time period during which the transmission data will not arrive normally, the transmission of the transmission data from the transmitting device to the wireless network is suspended ;
In the estimation of the noise generation pattern,
(e) The number or percentage of the transmitted data that did not arrive normally at the receiving device.
(f) the number or percentage of the received data that the transmitting/receiving device was not able to receive normally;
(g) the number or percentage of times when the signal strength observed in the measurement of the radio wave environment was equal to or greater than a predetermined threshold, excluding the cases in which the transmission/reception device was transmitting/receiving data;
(h) the time or percentage, excluding the time when the transmitting/receiving device was transmitting/receiving data, during which the channel usage time observed in the measurement of the radio wave environment was equal to or greater than a predetermined threshold value;
When at least one of the values is equal to or greater than a predetermined threshold, it is detected that the communication failure factor has occurred;
A predetermined time interval is divided into periods, and for each period,
storing a first time period during a certain period among the divided periods during which the communication interference factor is estimated not to have occurred in a noise occurrence pattern during the certain period, and a second time period during which the communication interference factor is estimated to have occurred;
storing the first time zone and the second time zone in consecutive periods other than the certain period that are a predetermined number of times or more among the divided periods;
When a time period stored as the first time period in the noise occurrence pattern in the continuous cycle is stored as the second time period in the noise occurrence pattern in the certain cycle, the noise occurrence pattern is updated so that the time period is included in the second time period;
When a time period stored as the second time period in the noise generation pattern in the continuous cycle is stored as the first time period in the noise generation pattern in the certain cycle, the noise generation pattern is updated so as to change the second time period to the first time period at a predetermined time or rate so that the time period is gradually included in the first time period.
A wireless communication method characterized by the above. A wireless communication method for performing data communication via a wireless network,
In order to correct correctable errors, including bit errors, that occur in data during communication, without the need to resend the data, a transmission data encoding process is performed in data transmission, and a reception data decoding process is performed in data reception;
estimating a noise occurrence pattern including occurrence timing of a communication interference element including a periodically occurring noise and a duration of the communication interference element based on at least one of the results of measurement of the radio wave environment of the wireless network and the success or failure of the data communication via the wireless network, including whether the error was corrected;
a time period during which data transmitted to the wireless network will not arrive normally at the receiving device based on the noise generation pattern, and during the time period during which the transmission data will not arrive normally, the transmission of the transmission data from the transmitting device to the wireless network is suspended ;
In the estimation of the noise generation pattern,
(a) The number or percentage of the transmitted data that did not arrive at the receiving device normally.
(b) the number or percentage of the received data that the transmitting/receiving unit was not able to receive normally;
(c) The number or percentage of times when the signal strength observed in the measurement of the radio wave environment was equal to or greater than a predetermined threshold, excluding the cases when the transceiver unit was transmitting or receiving data.
(d) A time or a ratio excluding a time when the transceiver unit is transmitting or receiving data during a channel usage time observed in the measurement of the radio wave environment that is equal to or greater than a predetermined threshold.
When at least one of the values is equal to or greater than a predetermined threshold, it is detected that the communication failure factor has occurred;
storing the occurrence of the communication failure element or the value of the communication failure element as time-series information together with the time when the communication failure element occurred;
moreover,
A predetermined time interval is divided into periods, and the same noise occurrence pattern is repeated for each period, and based on the time-series information, the occurrence of the communication failure factor is modeled to estimate the noise occurrence pattern.
A wireless communication method characterized by the above. A wireless communication program for performing data communication via a wireless network,
A procedure for performing an encoding process on transmission data during data transmission and a decoding process on received data during data reception so that correctable errors, including bit errors, occurring in data during communication can be corrected without retransmitting the data;
a step of estimating a noise occurrence pattern including occurrence timing of a communication disturbance element including a periodically occurring noise and a duration of the communication disturbance element based on at least one of the results of measurement of the radio wave environment of the wireless network and the success or failure of the data communication via the wireless network including whether the error was corrected;
a step of setting a time during which data transmitted to the wireless network will not arrive normally at the receiving device based on the noise generation pattern, and causing the transmitting device to suspend transmission of the transmission data to the wireless network during the time during which the transmission data will not arrive normally;
Equipped with
The procedure for estimating the noise generation pattern includes:
(e) The number or percentage of the transmitted data that did not arrive normally at the receiving device.
(f) the number or percentage of the received data that the transmitting/receiving device was not able to receive normally;
(g) the number or percentage of times when the signal strength observed in the measurement of the radio wave environment was equal to or greater than a predetermined threshold, excluding the cases in which the transmission/reception device was transmitting/receiving data;
(h) the time or percentage, excluding the time when the transmitting/receiving device was transmitting/receiving data, during which the channel usage time observed in the measurement of the radio wave environment was equal to or greater than a predetermined threshold value;
When at least one of the values is equal to or greater than a predetermined threshold, it is detected that the communication failure factor has occurred;
A predetermined time interval is divided into periods, and for each period,
storing a first time period during a certain period among the divided periods during which the communication interference factor is estimated not to have occurred in a noise occurrence pattern during the certain period, and a second time period during which the communication interference factor is estimated to have occurred;
storing the first time zone and the second time zone in consecutive periods other than the certain period that are a predetermined number of times or more among the divided periods;
When a time period stored as the first time period in the noise occurrence pattern in the continuous cycle is stored as the second time period in the noise occurrence pattern in the certain cycle, the noise occurrence pattern is updated so that the time period is included in the second time period;
and a step of updating the noise occurrence pattern so that, when a time period stored as the second time period in the noise occurrence pattern in the continuous cycle is stored as the first time period in the noise occurrence pattern in the certain cycle, the second time period is changed to the first time period at a predetermined time or rate so that the time period is gradually included in the first time period.
A wireless communication program comprising: A wireless communication program for performing data communication via a wireless network,
A procedure for performing an encoding process on transmission data during data transmission and a decoding process on received data during data reception so that correctable errors, including bit errors, occurring in data during communication can be corrected without retransmitting the data;
a step of estimating a noise occurrence pattern including occurrence timing of a communication disturbance element including a periodically occurring noise and a duration of the communication disturbance element based on at least one of the results of measurement of the radio wave environment of the wireless network and the success or failure of the data communication via the wireless network including whether the error was corrected;
a step of setting a time during which data transmitted to the wireless network will not arrive normally at the receiving device based on the noise generation pattern, and causing the transmitting device to suspend transmission of the transmission data to the wireless network during the time during which the transmission data will not arrive normally;
Equipped with
The procedure for estimating the noise generation pattern includes:
(a) The number or percentage of the transmitted data that did not arrive at the receiving device normally.
(b) the number or percentage of the received data that the transmitting/receiving unit was not able to receive normally;
(c) The number or percentage of times when the signal strength observed in the measurement of the radio wave environment was equal to or greater than a predetermined threshold, excluding the cases when the transceiver unit was transmitting or receiving data.
(d) A time or a ratio excluding a time when the transceiver unit is transmitting or receiving data during a channel usage time observed in the measurement of the radio wave environment that is equal to or greater than a predetermined threshold.
When at least one of the values is equal to or greater than a predetermined threshold, it is detected that the communication failure factor has occurred;
storing the occurrence of the communication failure element or the value of the communication failure element as time-series information together with the time when the communication failure element occurred;
moreover,
a step of dividing a predetermined time interval into a period, assuming that the same noise generation pattern is repeated in each period, and modeling the occurrence of the communication failure factor based on the time series information to estimate the noise generation pattern .

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