WO2011058925A1 - Wireless communication status acquiring method and radio station - Google Patents

Abstract

In a multihop wireless network, information about the communication environments of communication paths can be collected with the real time characteristic of data communication secured. In each of a plurality of stations, that is, relay stations and other radio stations, when a receiving unit receives a communication frame accommodating data, a local-station diagnosis information generating unit generates a local-station diagnosis information obtained by diagnosing the status of the communication environment of the local station. An other-station diagnosis information extracting unit extracts other-station diagnosis information from the received communication frame. A diagnosis information unifying unit unifies, based on accommodation format information, the local-station diagnosis information and the other-station diagnosis information and accommodates the unified diagnosis information into the communication frame. In this way, information about the statuses of the communication environments of the radio stations existing on communication paths can be collected, which allows the statuses of the communication paths to be diagnosed.

Description

Wireless communication state acquisition method and wireless station

The present invention relates to a technique for acquiring a communication state between wireless stations in a multi-hop wireless network.

A multi-hop wireless network is composed of a plurality of wireless stations, and transmits information transmitted from a wireless station serving as a terminal station via a wireless station in a range in which the terminal's radio waves can be received as a relay station. Step-by-step transmission to the wireless station that will be the station. Further, generally, the base station is connected to a wired network or the like, and transfers the received information to the control device that is the final destination.

In a multi-hop wireless network, a wired cable is not required between a terminal station, a relay station, and a base station, so that it is possible to reduce cable installation costs and maintenance costs such as periodic inspections. In addition, since a wired cable is not required, renewal of a radio station can be easily performed, and it is possible to flexibly cope with operations such as addition or change of functions. Furthermore, along with the progress of wireless technology, cost reduction of wireless communication devices such as wireless LAN (Local Area Network) and standardization of sensor network technology using Bluetooth (registered trademark), ZigBee (registered trademark), etc. are progressing. As a result, applications in the industrial field are increasing. For example, application examples in the industrial field have been applied to social infrastructure projects such as electric power and transportation, and monitoring / control networks of manufacturing industries such as FA (Factory Automation) and PA (Process Automation).

In addition, the wireless network for the industrial field is required to satisfy the reliability of information transmission. In Patent Document 1, a diagnostic packet is used to diagnose the state of the communication path of the wireless network. A method is disclosed. In the method disclosed in Patent Document 1, when a diagnostic packet is transmitted and a response indicating that the diagnostic packet is normally received is acquired, the communication path state is determined to be normal.

JP 2005-176161 A

However, in the invention disclosed in Patent Document 1, since a diagnostic packet is used, data to be originally transmitted cannot be transmitted during transmission / reception of the diagnostic packet. That is, there is a problem that the real-time property of data communication is impaired. Further, in the invention disclosed in Patent Document 1, since the transmission / reception period of the diagnostic packet and the transmission / reception period of the data communication packet are separated from each other, the indication is given in advance before communication between the wireless stations becomes impossible. There is a problem that it cannot be detected and diagnosed. Therefore, an object of the present invention is to acquire information on a communication environment of a communication path while ensuring real-time data communication in a multi-hop wireless network.

In order to solve the above-described problems, the present invention provides a wireless station that constitutes a multi-hop wireless network that transmits and receives a communication frame used for data communication in order of a terminal station, a relay station, and a base station, and receives the communication frame. Sometimes, diagnostic information relating to the communication environment of the local station is generated based on the reception state of the communication frame, and the generated diagnostic information is stored in the communication frame. Also, by generating diagnostic information when a communication frame is received, the number of times that diagnostic information is generated at the terminal station and base station that are the starting point of the communication frame is half the number of times that diagnostic information is generated at the relay station. turn into. Therefore, in order to increase the number of times diagnostic information is generated at the terminal station and the base station, a dummy communication frame is received from the adjacent radio station at a timing that does not impair the real-time property, and diagnostic information of the local station is generated. .

ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to collect the communication environment information of a communication path, ensuring the real-time property of data communication in a multihop wireless network.
Other objects, features and advantages of the present invention will become apparent from the following description of embodiments of the present invention with reference to the accompanying drawings.

It is a figure which shows an example of a structure of the multihop radio | wireless system in this embodiment. It is a figure which shows an example of a structure of a communication frame. It is a figure which shows an example of the routing table of a relay station. It is a figure which shows an example of the routing table of a base station. It is a figure which shows an example of the function which concerns on the diagnostic information of a relay station. It is a figure which shows the relationship between the diagnostic information of a communication frame, and a communication area. It is a figure which shows the flow of the process of the downlink direction of a multihop radio | wireless system. It is a figure which shows the flow of the process of the uplink direction of a multihop radio | wireless system. It is a figure which shows the example of log information. It is a figure which shows the example of the storage method of the diagnostic information of a communication frame. It is a figure which shows the example of the storage method of the diagnostic information of a communication frame. It is a figure which shows the example of the storage method of the diagnostic information of a communication frame. It is a figure which shows the example of the storage method of the diagnostic information of a communication frame. It is a figure which shows the example of the storage method of the diagnostic information of a communication frame. It is a figure which shows the example of the storage method of the diagnostic information of a communication frame. It is a figure which shows the method in which a base station produces | generates the diagnostic information of an own station. It is a figure which shows the method in which a terminal station produces | generates the diagnostic information of an own station.

Next, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail with reference to the drawings as appropriate.

The configuration of the multi-hop wireless system 1 in the present embodiment will be described with reference to FIG. In the multi-hop wireless system 1, the terminal station 130 acquires data (sensor values, etc.) of field devices 140 such as sensors and actuators and stores them in the communication frame 10 (see FIG. 2). Send to 110. The terminal station 130 and the field device 140 are communicably connected via a wired network. Between the terminal station 130 and the base station 110, relay stations 120 (120a, 120b,..., 120n), 121 (121a, 121b,... 121n), 122 (122a) that relay the communication frame 10 step by step. , 122b,..., 122n). For example, the communication frame 10 transmitted from the terminal station 130 is transmitted to the base station 110 using the communication paths of the relay station 120 and the relay station 121 together. That is, the communication path of the relay station 120 and the communication path of the relay station 121 transmit the communication frame 10 including the same data. The reason for using the communication path together is to ensure the reliability of information transmission. Even if a failure occurs in one of the communication paths, data can be delivered through the other communication path.

Then, the base station 110 transmits the data (sensor value and the like) stored in the received communication frame 10 to the control device 100 connected by a wired network. The direction in which data is transmitted from the terminal station 130 to the base station 110 in this way is referred to as “uplink”. Note that the communication frame 10 is transmitted and received in a wireless manner between the terminal station 130, the relay stations 120, 121, 122, and the base station 110.

In addition, the base station 110 stores an instruction to acquire a sensor value or the like in the communication data 13 (see FIG. 2) of the communication frame 10 and transmits it to the field device 140. Also at this time, the communication frame 10 is transmitted using, for example, the communication paths of the relay station 120 and the relay station 121 together. In this way, the direction in which data is transmitted from the base station 110 to the terminal station 130 is referred to as “downlink”. However, the same communication path is used for “uplink” and “downlink”.

In FIG. 1, only one terminal station 130 and one base station 110 are shown, but two or more each may be used. In addition, although three communication paths of the relay stations 120, 121, and 122 are described, it is sufficient that there are two or more communication paths of the relay station for the set of the base station 110 and the terminal station 130. Further, the number of relay stations existing on one communication path may be different for each communication path. Further, in order to ensure the reliability of information transmission between the base station 110 and the terminal station 130, two or more communication paths are used in combination. Each station 110, 120, 121, 122, and 130 includes two antennas, and each antenna performs communication at different radio frequencies. Further, which radio frequency is used between which stations is managed by the control device 100 and notified to each station.

Next, the configuration of the communication frame 10 will be described with reference to FIG. 2 (see FIG. 1 as appropriate). The communication frame 10 is generated by the base station 110 or the terminal station 130, and includes a frame header 11, diagnostic information 12, communication data 13, and a frame end 14 as shown in FIG. In the downlink direction, the frame header 11 stores information indicating the address of the destination terminal station 130 selected by the control device 100 and the address of the transmission source base station 110. The diagnostic information 12 stores diagnostic information indicating the state of the communication environment surrounding the base station 110, the relay station 120 (or the relay stations 121 and 122), and the terminal station 130. The items of the diagnostic information indicating the state of the communication environment include, for example, the radio wave intensity when the communication frame 10 is received, SNR (Signal to Noise Ratio), BER (Bit Error Rate), the number of error corrections using an error correction code, and the communication frame. The number of times of loss and the number of times of retransmission are associated with the time stamp at which the communication frame 10 was received. The communication data 13 stores data such as sensor values and instructions described above. The frame end 14 stores information indicating the end of the communication frame 10.

Here, the radio wave intensity is the radio wave intensity when the communication frame 10 is received. SNR is the ratio of the radio field intensity of noise to the radio field intensity of the signal of the communication frame 10. The BER is a ratio at which a bit does not stand at a correct position when the radio signal of the received communication frame 10 is demodulated. The number of error corrections is the number of times error correction has been performed using an error correction code. The number of lost communication frames is the number of times that the communication frame 10 has not been received. In order to measure the number of lost communication frames, information indicating the serial number of the communication frame 10 is stored in the communication data 13 of the communication frame 10, and it can be measured by detecting that the serial number jumps. The number of lost communication frames is determined when a predetermined time interval from the reception of the communication frame 10 to the arrival of the next communication frame 10 has elapsed or when the arrival of the next communication frame 10 has passed the scheduled time. The communication frame 10 may be determined to have been lost. The number of retransmissions is the number of times that the same communication frame 10 has been retransmitted.

The diagnostic information 12 of the communication frame 10 stores the diagnostic information each time the communication frame 10 passes through the base station 110, the relay stations 120, 121, 122, and the terminal station 130. This storage method will be described later.

Here, a method for establishing the communication path of the relay station and a selection method for determining which relay station to select when the base station 110 transmits the communication frame 10 to the terminal station 130 will be described (FIG. 1, 3A, 3B). First, each of the base station 110 and the relay stations 120, 121, and 122 is a routing table (set when the multihop wireless system 1 is constructed or distributed by the control device 100 when the multihop wireless system 1 is started up). 3A and 3B).

As shown in FIG. 3A, the routing table held by each of the relay stations 120, 121, and 122 includes a destination that transmits the communication frame 10 when it is upstream, a destination that transmits the communication frame 10 when it is downstream, The radio frequency used for communication is stored. When each of the relay stations 120, 121, and 122 receives the communication frame 10, it refers to the routing table shown in FIG. 3A and stores the destination in the communication data 13 of the communication frame 10 for transmission. When the relay station 120, 121, 122 that has received the communication frame 10 corresponds to the destination stored in the communication data 13, the relay station 120, 121, 122 transmits the communication frame 10 in order. Get information. If the relay station 120, 121, 122 does not correspond to the destination stored in the communication data 13, the relay station 120, 121, 122 discards the communication frame 10.

3B, the routing table held by the base station 110 includes the address of the terminal station 130 that is the destination of the communication frame 10 and the relay that can transmit the communication frame 10 to the terminal station 130. The addresses of the stations 120, 121, and 122 are associated with radio frequencies. The frame header 11 of the communication frame 10 transmitted by the base station 110 stores the address of the terminal station 130 that is the destination and the address of the base station 110 that is the transmission source. Further, the communication data 13 of the communication frame 10 stores one of the addresses of the relay stations 120a, 121a, and 122a as a destination indicating which relay stations 120, 121, and 122 are to be routed. Then, the relay stations 120 a, 121 a, and 122 a that have received the communication frame 10 acquire the information of the communication frame 10 and store it in the communication data 13 when the destination address stored in the communication data 13 corresponds. If the received address does not correspond to the destination address, the information of the communication frame 10 is discarded.

Next, functions related to the diagnostic information 12 of the relay station 120 will be described with reference to FIG. 4 (see FIGS. 1 and 2 as appropriate). In addition, since the function concerning the diagnostic information 12 of the relay stations 121 and 122 is the same as that of the relay station 120, description is abbreviate | omitted. As illustrated in FIG. 4, the relay station 120 includes a processing unit 310, a communication unit 320, and a storage unit 330.

The processing unit 310 includes a diagnostic information integration unit 311, a local station diagnostic information generation unit 312, and another station diagnostic information extraction unit 313. When the receiving unit 321 of the communication unit 320 receives the communication frame 10, the local station diagnostic information generation unit 312 indicates the local station diagnostic information based on the measurement result related to the state of the communication environment surrounding the local station. Diagnostic information 332 is generated. Then, the local station diagnosis information generation unit 312 stores the local station diagnosis information 332 in the storage unit 330. When the reception unit 321 receives the communication frame 10, the other station diagnosis information extraction unit 313 extracts the other station diagnosis information 333 indicating the diagnosis information of the other station from the received communication frame 10. Then, the other station diagnosis information extraction unit 313 stores the other station diagnosis information 333 in the storage unit 330.

The diagnostic information integration unit 311 reads the local station diagnostic information 332 and the other station diagnostic information 333 in the storage unit 330 and further stores a storage format indicating the storage format of the diagnostic information 13 of the communication frame 10 stored in the storage unit 330. Referring to the information 331, the read diagnostic information of the local station and the other station is integrated and stored in the diagnostic information 12 of the communication frame 10. The transmission unit 322 of the communication unit 320 transmits the communication frame 10 to the next station.

The communication unit 320 includes a reception unit 321 that receives the communication frame 10 and a transmission unit 322 that transmits the communication frame 10 storing the diagnosis information of the local station. The storage unit 330 stores storage format information 331, own station diagnosis information 332, and other station diagnosis information 333.

Next, functions related to the diagnostic information 12 of the base station 110, the terminal station 130, and the control device 100 will be described (not shown). The terminal station 130 and the base station 110 have the same functions as the relay station 120 shown in FIG. Further, the control device 100 receives the diagnostic information 12 of the communication frame 10 from the base station 110, diagnoses the state of the communication path based on the diagnostic information of each station, and outputs an instruction to switch the communication path based on the diagnostic result. To do.

Next, an outline of a method for transmitting diagnostic information in the present embodiment will be described with reference to FIG. In the downlink communication, the diagnostic information 12 of the communication frame 10 passes through the base station 110 every time it is transmitted in a forward manner from the relay station A (120A), the relay station B (120B), and the terminal station 130. Station diagnostic information is added. Note that relay station A (120A) and relay station B (120B) in FIG. 5 correspond to relay station 120a and relay station 120b in FIG. Specifically, even if the base station 110 receives communication data from the control device 100, the base station 110 does not receive the communication frame 10 by radio, and therefore does not generate diagnostic information of the own station. Therefore, nothing is stored in the diagnostic information 12 of the communication frame 10 transmitted from the base station 110 as indicated by 401. In the diagnostic information 12 of the communication frame 10 transmitted from the relay station A (120A), the diagnostic information of the relay station A is stored as indicated by 402. Further, in the diagnostic information 12 of the communication frame 10 transmitted from the relay station B (120B), the diagnostic information of the relay station A and the relay station B is stored as indicated by 403. And the terminal station 130 produces | generates the diagnostic information of an own station, when the communication frame 10 is received.

Next, in uplink communication, as in downlink communication, diagnostic information 12 of the communication frame 10 is transmitted from the terminal station 130 to the relay station B (120B), the relay station A (120A), and the base station 110. And the diagnostic information of the station that passed through is added each time. Specifically, in the diagnostic information 12 of the communication frame 10 transmitted from the terminal station 130, the diagnostic information generated when the communication frame 10 is received is added to the diagnostic information of 403, and the diagnostic information shown in 404 It becomes. Similarly, each time it is transmitted to relay station B (120B), relay station A (120A), and base station 110 by forward feed, it becomes diagnostic information shown in 405, 406, and 407, respectively. However, if there is no downlink communication and only uplink communication is performed, the diagnostic information of the station (indicated as (uplink) in FIG. 5) that has passed through the uplink communication is the diagnosis of the communication frame 10. Stored in information 12.

Here, the flow of processing related to diagnostic information in the multi-hop wireless system 1 will be described with reference to FIGS. FIG. 6 shows the flow of processing related to the downlink diagnostic information of the multi-hop wireless system 1. FIG. 7 shows a flow of processing related to uplink diagnostic information of the multi-hop wireless system 1.

As shown in FIG. 6, first, in step S <b> 601, the control device 100 transmits communication data such as a command value to the field device 140 to the base station 110. In addition to the command value, the communication data includes the address of the terminal station 130 and the address of the first relay station A (120A) on the communication path of the relay station. The first relay station A (120A) on the communication path of the relay station is determined based on the diagnostic information collected by the control device 100.

In step S602, the base station 110 stores the communication data in the communication data 13 of the communication frame 10. The communication data 13 of the communication frame 10 includes the address of the base station 110 that is the transmission source and the address of the relay station A (120A) that is the destination. In step S603, the base station 110 transmits the communication frame 10.

The relay station A (120A) receives the communication frame 10, and generates diagnostic information of the local station and stores it in the communication frame 10 in step S604. Further, the communication data 13 of the communication frame 10 includes its own address as the transmission source and the address of the destination relay station B (120B) determined by the routing table of FIG. 3A. In step S605, the relay station A (120A) transmits the communication frame 10. The relay station B (120B) receives the communication frame 10, and generates diagnostic information of the own station and stores it in the communication frame 10 in step S606. Further, the communication data 13 of the communication frame 10 includes its own address as the transmission source and the address of the destination terminal station 130 determined by the routing table of FIG. 3A. In step S607, the relay station B (120B) transmits the communication frame 10.

The terminal station 130 receives the communication frame 10, and generates diagnostic information of the local station in step S608. In step S609, data is received from the field device 140. Note that step S609 may be prior to step S608. In step S610, the terminal station 130 determines whether or not uplink data exists. If uplink data exists, the diagnostic information of the local station and the uplink data are stored in the communication frame 10 in step S701 shown in FIG. If there is no uplink data in step S610, a response indicating that the communication frame 10 has been received is used as uplink data. In step S701, the diagnostic information of the own station and the uplink data are transmitted in the communication frame 10. To store. The communication data 13 of the communication frame 10 includes information with the address of the relay station B (120B) stored in the communication data 13 of the communication frame 10 in step S607 as the destination and the own address as the transmission source. It is. In step S702, the terminal station 130 transmits the communication frame 10. In the frame header 11 of the communication frame 10 transmitted by the terminal station 130, the transmission source is the address of the terminal station 130 and the destination is the address of the base station 110.

The relay station B (120B) receives the communication frame 10, and generates diagnostic information of the local station and stores it in the communication frame 10 in step S703. Further, the communication data 13 of the communication frame 10 includes its own address as a transmission source and the address of the destination relay station A (120A) determined by the routing table of FIG. 3A. In step S704, the relay station B (120B) transmits the communication frame 10. The relay station A (120A) receives the communication frame 10, and generates diagnostic information of the local station in step S705 and stores it in the communication frame 10. Further, the communication data 13 of the communication frame 10 includes its own address as a transmission source and the address of the destination base station 110 determined by the routing table of FIG. 3A. In step S706, the relay station A (120A) transmits the communication frame 10.

The base station 110 receives the communication frame 10, and generates diagnostic information of the local station in step S707 and stores it in the communication frame 10. In step S708, the base station 110 transmits the communication frame 10 or the diagnostic information 12 and the communication data 13 of the communication frame 10 to the control device 100. In step S709, the control device 100 acquires the communication data stored in the communication data 13 of the received communication frame 10. In step S <b> 710, the control device 100 acquires the diagnostic information of each station stored in the diagnostic information 12. In step S711, the control device 100 diagnoses the path state based on the diagnosis information of each station acquired in step S710.

Route status diagnosis is performed based on information indicating the status of the communication environment. The items of the diagnostic information indicating the state of the communication environment include, for example, the radio wave intensity when the communication frame 10 is received, BER (Bit Error Rate), SNR (Signal to Noise Ratio), the number of retransmissions, as described above. The number of error corrections using error correction codes, the number of lost communication frames, and the like. Any one or a combination of two or more of these items is used for comparison with a preset threshold value. Then, when the value of any one or a combination of two or more of the items exceeds the threshold value, it is determined that the route state has deteriorated, and communication disconnection is avoided.

In step S712, the control device 100 performs path switching (avoidance of communication disconnection) based on the path state diagnosis result in step S711. The switching of the route is performed by rewriting the routing table (see FIGS. 3A and 3B) so that, for example, (1) the radio frequency of the same communication route is switched, and (2) the entire communication route is switched. Further, the rewriting of the routing table is performed by storing and notifying the information (1) or (2) described above with the corresponding station as the destination in the communication data in step S601 of FIG.

The switching of the entire communication path (2) may be performed by switching all the communication path groups used before the switching, or it is determined that the path state is deteriorated among the communication path groups. It is also possible to set a new set of communication paths by switching only the communication paths. In addition, only a station that is determined to have a deteriorated path state may be switched to a station on another communication path.

FIG. 8 shows an example of log information when communication disconnection avoidance is executed. For example, in the log number 1, when the time (time stamp) is 16:25:16, the interval from the relay station A to the relay station B based on the number of retransmissions of the determination information 1 being 3 It can be seen that the radio frequency is changed. For example, in log number 3, when the time (time stamp) is 16:25:17, the log number of determination information 1 is log number 1 and the log number of determination information 2 is log number 2. Based on the above, it can be seen that the communication path 2 is changed. By collecting such logs, for example, in the section from relay station A to relay station B, it is used to learn a communication environment such as the presence of jamming waves of a specific frequency and establish a countermeasure. Can do. Further, by considering the time (time stamp), it is possible to grasp the presence of jamming radio waves that cause communication jamming for each time zone and change the radio frequency in advance.

Next, a storage format of diagnostic information in the diagnostic information 12 of the communication frame 10 will be described with reference to FIGS. 9A to 9F. FIG. 9A shows a case where the storage location (memory address or the like) of diagnostic information is predetermined for each station. Each station has a different storage location in the downlink direction and the uplink direction. FIG. 9B shows a case where the storage location of the diagnostic information of the station is determined in advance for each item of diagnostic information.

FIG. 9C shows a case in which each diagnosis information 1 to n is stored with the identification number for identifying the station at the head, in the left-justified manner. As an identification number, for example, a MAC (Media Access Control) address that is a device-specific number, an IP (Internet Protocol) address, a number according to other various communication standards, or an administrator of the multi-hop wireless system 1 is assigned. Number. The identification number and the station are associated with each other and stored in the control device 100.

FIG. 9D and FIG. 9E show cases where the diagnostic information and the identification number may be arranged anywhere within the storage position range when the number of items of diagnostic information n is known. FIG. 9F shows a case where the number of items of diagnostic information is known and the identification information is omitted. In the case of FIG. 9F, as described above, the control device 100 holds information related to the routing table shown in FIGS. 3A and 3B in advance, and transmits / receives the communication frame 10 via any communication path of which relay station. Since the communication data 13 received from the base station 110 includes the address of the transmission source relay station, the communication path of the received communication frame 10 can be specified. Therefore, as shown in FIG. 9F, as long as the diagnostic information is written in the left-justified manner, it is possible to specify which station the diagnostic information belongs to. Each storage format shown in FIGS. 9A to 9F is already statically stored before power-up of each station, or is it distributed from the control device 100 before the start of data communication after power-up. Are stored in each station.

<Modification 1>
With the information stored in the diagnostic information 12 of the communication frame 10 shown in FIG. 5 described above, the control device 100 cannot acquire the diagnostic information of the base station 110 in the downlink direction. Therefore, as a first modification, a method in which the base station 110 generates diagnosis information of the own station in the downlink direction will be described with reference to FIG. The same steps as those in FIG. 6 are denoted by the same reference numerals. In step S1001, relay station A (120A) next to base station 110 transmits a dummy communication frame to base station 110. The transmission timing of this dummy communication frame is, for example, when the relay station A (120A) itself is not transmitting and receiving and when a predetermined time has elapsed since the previous transmission of the communication frame 10 to the base station 110. Suppose that This is because real-time performance is not impaired. In the communication data 13 of the dummy communication frame, information for identifying that the communication frame is a dummy is described.

In step S1002, the base station 110 receives a dummy communication frame and generates diagnostic information of the own station. Note that, when the base station 110 receives a dummy communication frame, the base station 110 does not transmit the dummy communication frame to the control device 100. When the base station 110 receives the communication data in step S601 from the control device 100, the base station 110 stores the diagnostic information and communication data of the local station generated immediately before in the communication frame 10 in step S1003. Next, in step S603, the base station 110 transmits a communication frame to the relay station A (120A). Since the transmission after step S603 is the same as steps S604 to S610, the description thereof will be omitted.

<Modification 2>
Next, with the information stored in the diagnosis information 12 of the communication frame 10 shown in FIG. 5 described above, the control device 100 cannot acquire the diagnosis information of the terminal station 130 in the uplink direction. Therefore, as a second modification, a method in which the terminal station 130 generates its own diagnostic information in the uplink direction will be described with reference to FIG. In this case, for example, an instruction to automatically and continuously acquire sensor values from the control device 100 to the terminal station 130 and to automatically transmit the acquired sensor values to the control device 100 is given. In this case, the terminal station 130 actively continues to transmit the sensor value to the control device 100. In this case, since the terminal station 130 is the starting point of the communication frame 10, the terminal station 130 does not receive the downstream communication frame 10. Therefore, the terminal station 130 cannot store the diagnostic information of the local station in the diagnostic information 12 of the communication frame 10.

Here, a method for acquiring diagnostic information of the terminal station 130 in the uplink direction will be described with reference to FIG. The same steps as those in FIGS. 6 and 7 are denoted by the same reference numerals. In step S1101, the relay station B (120B) adjacent to the terminal station 130 transmits a dummy communication frame to the terminal station 130. The transmission timing of this dummy communication frame is, for example, when the relay station B (120B) itself is not transmitting and receiving and when a predetermined time has elapsed since the previous transmission of the communication frame 10 to the terminal station 130. Suppose that This is because real-time performance is not impaired. In the communication data 13 of the dummy communication frame, information for identifying that the communication frame 10 is a dummy is described.

In step S1102, the terminal station 130 receives the dummy communication frame and generates its own diagnostic information. Note that the terminal station 130 does not transmit the uplink communication frame 10 to the control device 100 when receiving the dummy communication frame. When the terminal station 130 receives data from the field device 140 as in step S609, in step S701, the terminal station 130 stores the diagnostic information and communication data of the local station generated immediately before the data in the communication frame 10. Next, in step S702, the terminal station 130 transmits a communication frame to the relay station B (120B). Since the transmission after step S702 is the same as steps S703 to S712, the description thereof will be omitted.

As described above, in the present embodiment, the communication frame 10 is transmitted in the multi-hop wireless system 1 that transmits and receives the communication frame 10 storing data communication between the base station 110, the relay stations 120, 121, and 122, and the terminal station 130. When received, it measures the state of the communication environment surrounding the station, generates diagnostic information, and stores the diagnostic information in the communication frame 10. Therefore, the real-time property of data communication is not impaired. In this embodiment, the diagnostic information of the relay stations 120, 121, and 122 can be acquired for both the uplink direction and the downlink direction. However, for the base station 110 and the terminal station 130, the diagnosis information can be obtained only in one direction. can not get. Therefore, according to the first and second modifications, the diagnostic information can be acquired in both directions by using the dummy communication frame 10 at a timing that does not impair the real-time property of data communication.

Although the above description has been made with reference to embodiments, the present invention is not limited thereto, and it will be apparent to those skilled in the art that various changes and modifications can be made within the spirit of the present invention and the scope of the appended claims.

DESCRIPTION OF SYMBOLS 1 Multihop radio | wireless system 10 Communication frame 12 Diagnostic information 13 Communication data 100 Control apparatus 110 Base station (radio station)
120, 121, 122 Relay station (wireless station)
130 Terminal station (wireless station)
140 Field device 310 Processing unit 320 Communication unit 321 Receiving unit 322 Transmitting unit 330 Storage unit

Claims (6)

In a multi-hop wireless system composed of a plurality of wireless stations and performing data communication between the wireless stations in a step-by-step manner, wireless communication status acquisition is performed to acquire the status of the communication environment of each wireless station on the data communication path. A method,
Each radio station includes a processing unit and a communication unit,
When the communication unit receives the data for data communication including the diagnostic information of the other station indicating the state of the communication environment of each wireless station that has already passed through from the other wireless station until reaching the wireless station,
The processing unit generates diagnostic information of the local station indicating a communication environment state based on a reception state of the received data, and the diagnostic information of the local station is stored in the received data of the other station In addition to diagnostic information, store in the data,
The wireless communication state acquisition method, wherein the communication unit transmits the data to the next wireless station. Each radio station further includes a storage unit,
The processing unit extracts the diagnostic information of the other station from the received data, temporarily stores the diagnostic information of the own station and the diagnostic information of the other station in the storage unit, and reads the reading from the storage unit The diagnostic information of the local station and the diagnostic information of the other station are integrated to generate new diagnostic information, and the new diagnostic information is replaced with the diagnostic information of the other station stored in the received data. The wireless communication state acquisition method according to claim 1, wherein the wireless communication state acquisition method stores the data in the data. A communication unit of a radio station next to the radio station serving as a starting point of the communication path of the data communication,
The wireless station that becomes the starting point when the data for dummy data communication is not transmitted / received by the own station and when a predetermined time has elapsed since the previous transmission to the wireless station that is the starting point The wireless communication state acquisition method according to claim 2, further comprising: The items of the diagnostic information include any of the radio wave intensity when the data is received, SNR (Signal to Noise Ratio), BER (Bit Error Rate), the number of error corrections using an error correction code, the number of communication frame loss, and the number of retransmissions. The wireless communication state acquisition method according to claim 1, wherein the wireless communication state acquisition method is a combination. A wireless station used in a multi-hop wireless system configured by a plurality of wireless stations and performing data communication step by step between the wireless stations,
A communication unit for transmitting and receiving data for data communication including diagnostic information indicating the state of the communication environment of the local station or another wireless station;
When the data communication data including diagnostic information of other stations indicating the status of the communication environment of each wireless station that has already passed before the communication unit reaches the local station is received, the reception status of the received data Based on the information, the diagnostic information of the own station indicating the state of the communication environment is generated, and the diagnostic information of the own station is added to the diagnostic information of the other station stored in the received data and stored in the data A wireless station comprising a processing unit. Each radio station further includes a storage unit,
The processing unit extracts the diagnostic information of the other station from the received data, temporarily stores the diagnostic information of the own station and the diagnostic information of the other station in the storage unit, and reads the reading from the storage unit The diagnostic information of the local station and the diagnostic information of the other station are integrated to generate new diagnostic information, and the new diagnostic information is replaced with the diagnostic information of the other station stored in the received data. The radio station according to claim 5, wherein the radio station is stored in the data.

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