WO2016158866A1

WO2016158866A1 - Communication device, authentication device, and network system

Info

Publication number: WO2016158866A1
Application number: PCT/JP2016/059947
Authority: WO
Inventors: 陽輔西潟
Original assignee: 三菱電機株式会社
Priority date: 2015-03-30
Filing date: 2016-03-28
Publication date: 2016-10-06
Also published as: JPWO2016158866A1

Abstract

Provided is a communication device which is a node (10) that is subordinate to an aggregation device and that forms a tree-shaped wireless multi-hop network, the communication device comprising: a time management unit (18) for adjusting the time of the device by acquiring time information from the aggregation device or another communication device; a message processing unit (17) that, after the time management unit (18) has adjusted the time of the device, determines on the basis of the time of the adjusted device whether it is necessary to carry out authentication for joining the wireless multi-hop network; and a message transmission unit (13) that, in a case where it was determined that authentication is necessary, transmits the signal required for authentication to an authentication device which determines whether the communication device is a device able to join the wireless multi-hop network.

Description

Communication device, authentication device, and network system

The present invention relates to a communication device constituting a wireless multi-hop network system.

A wireless multi-hop network system is composed of a terminal, an aggregation device, a higher-level device of the aggregation device, and the like, and generally has a network configuration in which terminals are accommodated in a tree shape under the aggregation device. The aggregation device or a higher-level device of the aggregation device can collect data from each terminal by hopping a plurality of terminals. For example, each terminal transmits data to the aggregation device by transmitting the measured data to the upper terminal and transmitting data received from the lower terminal to the upper terminal. By such a procedure, the aggregation device or the host device collects data measured at each terminal. The communication between the terminals and between the terminals and between the terminals and the aggregation device is configured by applying, for example, specific low power radio and the IEEE 802.15.4 standard.

In the above-described wireless multi-hop network system, the aggregation device or the host device has a function of determining whether or not terminal authentication, that is, a terminal that wants to participate in the network may participate in the network. The determination as to whether or not to join a terminal that wishes to participate is made using an authentication method called EAP-PSK (A Pre-Shared Key Extensible Authentication Protocol (EAP) Method), for example. Information related to the authentication method can be transmitted by an AA (Authentication and Authorization) protocol such as PANA (Protocol for Carrying Authentication for Network Access) or RADIUS (Remote Authentication Dial In User Service).

The terminal executes terminal authentication when the power is turned on. Prior to terminal authentication, a wireless channel to be used is determined by using an active scan using a Beacon signal defined in the IEEE 802.15.4 standard. In addition, after determining the wireless channel to be used, the transmission destination of a message related to terminal authentication is determined, and terminal authentication is performed. If terminal authentication is successful, MSK (Master Session Key) and EMSK (Extended Master Session Key), which are information for generating an encryption key, can be shared (for example, see Non-Patent Document 1).

In general, terminal authentication has an expiration date for the authentication. For example, there are cases in which the absolute time until the expiration date is notified, the remaining time until the expiration date is notified, etc. is there. In either case, terminal authentication is performed again based on the expiration date.

Also, there are cases where the terminal is powered off. In the case of a configuration in which the terminal operates by receiving power supply from a commercial power supply instead of a battery, for example, when a power failure occurs, the terminal existing in the power failure occurrence area is powered off. When recovering from a power failure, the power is turned on and channel scanning and terminal authentication are performed again.

When the technology disclosed in Non-Patent Document 1 is applied, when the terminal recovers from the power failure, the terminal attempts encrypted communication using the master key that is the MSK or EMSK that has been replaced in the terminal authentication performed before the power failure. When encryption communication fails, such as when there is no response, terminal authentication is performed again with the other party to update the master key.

However, when the technology disclosed in Non-Patent Document 1 is applied to a wireless multi-hop network system, the following problems may occur when power is restored from a power failure.

In a wireless multi-hop network system to which the technology disclosed in Non-Patent Document 1 is applied, when a terminal recovers after a power failure, an apparatus that is an authentication partner via a multi-hop communication path between the terminals, Specifically, cryptographic communication is attempted with an aggregation device or a higher-level device such as a server higher than the aggregation device. When it is determined that there is a problem with the encryption communication, the terminal performs terminal authentication again. Therefore, the transmission of messages by each terminal constituting the tree, specifically, the transmission of messages related to the authentication sequence is concentrated in a short period of time, and there is radio resource depletion and radio congestion in the vicinity of the aggregation device that is the message transmission destination. As a result, communication quality may be degraded.

The present invention has been made in view of the above, and an object of the present invention is to obtain a communication device capable of reducing the consumption of radio resources in a radio multi-hop network system.

In order to solve the above-described problems and achieve the object, the present invention is a communication device that is under the control of an aggregation device and forms a tree-like wireless multi-hop network, and the time from the aggregation device or another communication device. Time adjustment means for acquiring information and adjusting the time of the own apparatus, and after the time adjustment means adjusts the time of the own apparatus, the wireless multi-hop network is entered based on the adjusted time of the own apparatus. A processing means for determining whether or not authentication processing is necessary, and an authentication device for determining whether or not the communication device is a device capable of entering the wireless multi-hop network when the authentication processing is determined to be necessary On the other hand, transmission means for transmitting a signal requesting authentication processing is provided.

According to the present invention, it is possible to reduce the consumption of radio resources in the radio multi-hop network system.

The figure which shows the structural example of a wireless multihop network system Diagram showing an example of node configuration The figure which shows the structural example of an aggregation apparatus The figure which shows the structural example of a time synchronous request message The figure which shows the structural example of a time synchronous response message Flow chart showing an example of node operation after power recovery The figure which shows an example of the operation | movement which a node synchronizes time with an aggregation apparatus. The figure which shows the other structural example of a wireless multihop network system Diagram showing an example of the configuration of the authentication server The figure which shows an example of the hardware which implement | achieves a node, an aggregation apparatus, and an authentication server

Hereinafter, a communication device and a wireless multi-hop network system according to an embodiment of the present invention will be described in detail based on the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration example of a wireless multi-hop network system according to the present embodiment. The wireless multi-hop network system includes a plurality of

nodes

10a, 10b, and 10c and an aggregation device 20, and has a tree topology.

Nodes

10a, 10b and 10c are wireless communication terminals having the same function. In the following description, when it is not necessary to distinguish the

nodes

10a, 10b, and 10c, they may be collectively referred to as the node 10. Moreover, the node 10 and the aggregation apparatus 20 should just be 1 or more, and the number described in FIG. 1 is an example, Comprising: It does not limit to this. Each of the node 10 and the aggregation device 20 has individual identification information. The

nodes

10a, 10b, and 10c have identification information 10a_adr, 10b_adr, and 10c_adr, respectively, and the aggregation device 20 is described as having identification information 20_adr.

When receiving a signal from another node 10 or the aggregation device 20, the node 10 which is a communication device according to the present invention checks whether it needs to be transferred, and performs transfer processing if transfer is necessary. In addition, the node 10 has a clock function, acquires time information from the aggregation device 20 or another node 10 that has completed time synchronization with the aggregation device 20, and the time indicated by the acquired time information It is possible to synchronize the time with the aggregation device 20 by adjusting the local time of the own device.

In the following description, another node 10 and the aggregation device 20 when viewed from a certain node 10 may be collectively referred to as other terminals. For example, for the node 10a of the wireless multi-hop network system shown in FIG. 1, the

nodes

10b and 10c and the aggregation device 20 are other terminals. The other terminals for the aggregation device 20 are

nodes

10a, 10b, and 10c.

FIG. 2 is a diagram illustrating a configuration example of the node 10. The node 10 needs to transmit to the other node 10 or the aggregation device 20 and the wireless communication unit 12 that transmits / receives a radio signal to / from the other node 10 or the aggregation device 20 via the antenna 11. A message transmission unit 13 that outputs a message to the wireless communication unit 12 to request transmission, a message reception unit 14 that receives a message from another node 10 or the aggregation device 20, and a message that the message transmission unit 13 transmits are generated. Directly from the message generation unit 15, the storage unit 16 that stores various information, the message processing unit 17 that receives and analyzes the message received by the message reception unit 14, and executes an operation according to the analysis result, and the aggregation device 20 Time for receiving and holding the acquired time information or the time information acquired via another node 10 It includes a processing section 18, the.

The message transmission unit 13 receives a message that needs to be transmitted to another node 10 or the aggregation device 20 from the message generation unit 15, transfers the message to the wireless communication unit 12, and requests transmission. For example, the message transmission unit 13 performs calculation such as transmission timing in accordance with rules such as CSMA-CA (Carrier Sense Multiple Access-Collision Avoidance).

The message receiving unit 14 receives a message transmitted from another node 10 or the aggregation device 20 to the own device via the antenna 11 and the wireless communication unit 12 and passes the message to the message processing unit 17.

The message generator 15 generates a message that needs to be transmitted to another node 10 or the aggregation device 20 and a message that needs to be transferred. In the case of transfer, the message generator 15 receives a message to be transferred from the message processor 17 and rewrites the address. Further, the message generation unit 15 generates a time synchronization request, a message related to terminal authentication, and the like according to an instruction from the message processing unit 17.

The storage unit 16 is configured by a non-volatile memory, and the MAC (Media Access Control) address and IP (Internet Protocol) address of the own node, the other node 10 and the aggregation device that constitute the wireless mesh network system together with the own node device Holds 20 MAC addresses and IP addresses. The storage unit 16 also holds route information called a routing table. For example, at least one of the MAC address and IP address of the parent node that is the next hop is stored as route information to the aggregation device 20. The storage unit 16 further holds at least one authentication key and encryption key. The authentication key is used for terminal authentication, and the aggregation device 20 that is the other party of terminal authentication also holds the authentication key having the same value. The encryption key is generated or distributed at the time of terminal authentication. The encryption key generated or distributed at the time of terminal authentication is managed in association with the expiration date of authentication. That is, when authentication is invalidated due to the expiration of the expiration date, the encryption key is also invalidated. The encryption key is used when encrypting a frame in which a message to be transmitted to the aggregation device 20 is stored. The encryption key is updated when the validity period of terminal authentication ends and re-authentication is performed. The encryption key is updated based on a common authentication key held by the aggregation device 20 that performs authentication and the node 10 and information exchanged between the aggregation device 20 and the node 10 at the time of terminal authentication. In general, a key is generated, but a new encryption key generated in the aggregation device 20 can be transmitted to the node 10 and updated.

The message processing unit 17 analyzes the message received from the message reception unit 14 and causes the message generation unit 15 to generate a response message, and performs setting and reading of values between the storage unit 16 and the time management unit 18. Then, the message generation unit 15 is notified of a message generation opportunity. For example, when a time synchronization request message is received, the message processing unit 17 checks whether or not the time management unit 18 holds the time. If the time management unit 18 holds the time, the message generation unit generates the held time as a message. Notifying the unit 15 and instructing generation of a time synchronization response message. Further, when the message processing unit 17 receives a time synchronization response message corresponding to the time synchronization request message transmitted by the own device, the message processing unit 17 sets the time notified by the time synchronization response message in the time management unit 18. Further, when the message processing unit 17 receives a message related to terminal authentication, the message processing unit 17 instructs the message generation unit 15 to generate a response message according to the content of the received message. The message processing unit 17 further instructs the message generation unit 15 to generate messages related to these processes when performing time synchronization processing, terminal authentication processing, and the like. The message processing unit 17 constitutes an encryption key update unit and a time information transmission unit.

The time management unit 18 is a clock circuit configured by, for example, a crystal resonator, etc., and self-runs after setting the time, and holds time information indicating the local time of the own device. If the power supply is lost, the time information is lost. In this case, time information is transmitted from the aggregation device 20, and when the time management unit 18 of the node 10 receives the time information directly from the aggregation device 20 or via another node 10, the time information is held. . As a result, each node 10 can operate in synchronization with the time held by the aggregation device 20. The time information is transmitted from the node 10 or the aggregation device 20 that is the transmission destination of the time synchronization request message as a time synchronization response message for the time synchronization request message transmitted by each node. The time management unit 18 constitutes time adjustment means.

FIG. 3 is a diagram illustrating a configuration example of the aggregation device 20. The aggregation device 20 outputs an antenna 21, a wireless communication unit 22 that transmits and receives wireless signals to and from the node 10 via the antenna 21, and a message that needs to be transmitted to the node 10 to the wireless communication unit 22 for transmission. A message transmission unit 23 that requests a message, a message reception unit 24 that receives a message from the node 10, a message generation unit 25 that generates a message transmitted by the message transmission unit 23, a storage unit 26 that stores various information, and a message A message processing unit 27 that receives and analyzes a message received by the reception unit 24 and executes an operation according to the analysis result; and a time management unit 28 that receives and holds time information acquired from an external time source. Prepare.

Among the above-described components of the aggregation device 20, the operations of the antenna 21, the wireless communication unit 22, the message transmission unit 23, the message reception unit 24, and the message processing unit 27 are the same as the antenna 11 of the node 10, the wireless communication unit 12, and the message transmission. Since it is the same as the unit 13, the message receiving unit 14, and the message processing unit 17, detailed description thereof is omitted.

Unlike the storage unit 16 of the node 10, the storage unit 26 of the aggregation device 20 does not hold the address of the parent node of the next hop that is route information. The storage unit 26 holds, as route information, the downlink route from the own device, that is, the downlink route information of each node 10 under the own device.

The time management unit 28 of the aggregation device 20 holds time information acquired from an external time source by a time information acquisition unit (not shown). The time source is, for example, an NTP (Network Time Protocol) server. Time information may be supplied using GPS (Global Positioning System) or the like.

Since the time information held by the time management unit 28 of the aggregation device 20 is acquired from an external time source as described above, the message generation unit 25 of the aggregation device 20 is different from the message generation unit 15 of the node 10 in that No synchronization request message is generated.

Next, the configuration of the messages related to time synchronization among the messages transmitted and received by the node 10 and the aggregation device 20 according to the present embodiment will be described.

FIG. 4 is a diagram illustrating a configuration example of a time synchronization request message. The time synchronization request message includes a local destination 41, a local transmission source 42, and a message type 43. In the local destination 41, the MAC address or IP address of the node 10 or the aggregation device 20 that is the transmission destination of the time synchronization request message is set. The local transmission source 42 is set with the MAC address or IP address of the node 10 that is the transmission source of the time synchronization request message. In the message type 43, information indicating that it is a time synchronization request message is set.

FIG. 5 is a diagram illustrating a configuration example of a time synchronization response message. The time synchronization response message includes a local destination 51, a local transmission source 52, a message type 53, and a time 54. In the local destination 51, the MAC address or IP address of the node 10 that is the transmission destination of the time synchronization response message is set. In the local transmission source 52, the MAC address or IP address of the aggregation device 20 or the node 10 that is the transmission source of the time synchronization response message is set. In the message type 53, information indicating a time synchronization response message is set. At time 54, time information held by the node 10 or the aggregation device 20 that is the transmission source of the time synchronization response message is set.

Subsequently, the operation until the wireless multi-hop network system shown in FIG. 1 is formed by the node 10 and the aggregation device 20 described above will be described.

When the wireless multi-hop network system shown in FIG. 1 is formed, generally, the aggregation device 20 is first activated to start operation, and then the node 10, that is, the

nodes

10a, 10b, and 10c is activated. Start operation. The aggregation device 20 performs an authentication process by verifying whether each node 10 holds a common authentication key necessary for entering the network system.

The aggregation device 20 acquires time information from a time source (not shown) when the power is turned on and started. For example, time information is acquired from an NTP server, GPS, or the like. The acquired time information is managed by the time management unit 28. The time management unit 28 sets the time of the own device, that is, the aggregation device 20 at the time indicated by the acquired time information.

When the node 10 is powered on and activated, the node 10 starts an entry operation to the wireless multi-hop network system and performs a channel scan. Hereinafter, the entry operation to the wireless multi-hop network system may be referred to as the entry operation to the network. A wireless multi-hop network system may be referred to as a network.

The channel scan is a process for investigating whether there is an aggregation device 20 or another node 10 that can be connected to the surroundings. For example, an active scan or a passive scan as defined in IEEE 802.15.4 is performed. It is investigated whether other terminals that can be connected, that is, the connectable aggregation device 20 and other nodes 10 exist in the surroundings. When there are a plurality of usable channels, the channel scan periodically checks the presence of other connectable terminals in all usable channels while switching the channels. When there is another terminal that can be connected, the channel in which the other terminal exists is selected and determined as the channel to be used. When a specific channel is specified as a use channel, the specified channel is determined as a use channel without performing channel scanning.

After determining the channel, the node 10 acquires information indicating the route information from each of the other peripheral terminals that can be connected to the aggregation device 20, the quality information of the route such as the number of hops to the aggregation device 20, and the electric field strength. Based on the acquired information, a parent node serving as a route to the aggregation device 20 is selected from other connectable peripheral terminals. For example, the node 10a existing at a 1-hop position capable of direct communication with the aggregation device 20 selects the aggregation device 20 as a parent node.

When the parent node is selected, the node 10 starts terminal authentication processing. The terminal authentication process can be performed using an AA (Authentication and Authorization) method such as PANA and an authentication method such as EAP-PSK. When the node 10 requests the aggregation device 20 to authenticate its own device, the aggregation device 20 determines whether the requesting node 10 is a terminal that can participate in the network.

When the aggregation device 20 determines that the node 10 requesting terminal authentication is a terminal that can participate in the network, a notification of successful authentication is transmitted from the aggregation device 20 to the node 10, and the node 10 notifies that it has entered the network. Is transmitted to the aggregation device 20. Note that the notification from the node 10 to the aggregation device 20 can be encrypted and transmitted using a new encryption key generated in the course of the authentication process. With the above procedure, the entry operation of the node 10 to the network is completed.

The

nodes

10b and 10c that cannot directly communicate with the aggregation device 20 can also enter the network in the same procedure. The node 10b selects the node 10a as a parent node, and communicates with the aggregation device 20 using the node 10a as a relay terminal. Similarly, the node 10c selects the node 10a as a parent node.

By such a procedure, a wireless multi-hop network having the aggregation device 20 as the top of the tree is formed.

Each node 10 stores the encryption key obtained when the terminal authentication is successful when the entry operation to the wireless multi-hop network system is normally completed, and the identification information of the parent node obtained by channel scanning. To remember. Here, the selected channel may also be stored. In this case, it is possible to efficiently search for a channel in which another terminal that can be connected exists by executing a search for another terminal by the next channel scan from the stored channel. The aggregation device 20 stores in the storage unit 26 an encryption key to be shared with the node 10 for which terminal authentication has been successful.

The encryption key can be generated by using the terminal authentication function by EAP-PSK and using the encryption key generated in the process of terminal authentication. Communication between the node 10 and the aggregation device 20 can be performed using a common key encryption such as AES (Advanced Encryption Standard). When transmitting a control signal to each node 10, the aggregation device 20 encrypts transmission information such as a control signal using an encryption key shared with the node 10. Similarly, each node 10 encrypts information to be transmitted to the aggregation device 20 by using an encryption key shared with the aggregation device 20.

The aggregating apparatus 20 can collect and aggregate information acquired by each node 10 using a sensor or the like (not shown), for example, power usage information from each node 10.

Next, the startup procedure of the node 10 when power is restored from a power failure in the wireless multi-hop network system having the configuration shown in FIG. 1 will be described. Here, it is assumed that the power supply to all the nodes 10 and the aggregation device 20 is stopped due to the occurrence of a power failure, and when the power is restored, the power supply to all the nodes 10 and the aggregation device 20 is resumed and automatically restarted. Do. After power recovery, the aggregation device 20 that is the top of the tree acquires time information from the outside and adjusts the time. The operation when the aggregation device 20 is activated is as described in the description of the operation when the wireless multi-hop network system shown in FIG. 1 is formed.

The operation of the node 10 will be described with reference to FIG. 1, FIG. 2, and FIG. FIG. 6 is a flowchart showing an operation example of the node 10 after the power recovery.

After the power recovery, in the node 10, first, the message processing unit 17 reads the identification information of the parent node before the power failure from the storage unit 16 (step S11). The identification information is a MAC address, an IP address, or the like.

Next, the node 10 transmits a time synchronization request message to the parent node indicated by the identification information read in step S11 (step S12). That is, the message processing unit 17 instructs the message generation unit 15 to generate a time synchronization request message, the message generation unit 15 that receives the instruction generates a time synchronization request message, and the time synchronization request generated by the message generation unit 15 The message transmission unit 13 transmits the message. For example, since the parent node of the node 10 a is the aggregation device 20, the node 10 a transmits a time synchronization request message to the aggregation device 20. Since the parent node of the

nodes

10b and 10c is the node 10a, the

nodes

10b and 10c transmit a time synchronization request message to the node 10a. In the operation after power recovery, the

nodes

10a, 10b and 10c transmit the time synchronization request message at almost the same timing.

In addition, in order to avoid complicated description, in the following description, description of the operation of each unit in the node 10 and the operation of each unit in the aggregation device 20 is omitted.

The aggregation device 20 that has received the time synchronization request message from the node 10a holds the time information when the time synchronization request message is received, and therefore transmits a time synchronization response message to the node 10a. As shown in FIG. 5, the time synchronization response message includes time information held by the message transmission source terminal as time 54. On the other hand, the node 10a that has received the time synchronization request message from the

nodes

10b and 10c does not hold the time information at the time when the time synchronization request message is received. Since the process for adjusting the time of the device is not completed, the time synchronization response message is not transmitted. When the node 10a receives the time synchronization response message from the aggregation device 20 after receiving the time synchronization request message from the

node

10b or 10c, the node 10a sends the time synchronization response message to the requesting node 10b after the time adjustment of its own device is completed. Or you may make it transmit to 10c. If the

nodes

10b and 10c cannot receive the time synchronization response message even after a predetermined time has elapsed after transmitting the time synchronization request message, the

nodes

10b and 10c retransmit the time synchronization request message. Further, the

nodes

10b and 10c may transmit the time synchronization request message at a timing later than that of the node 10a. That is, each node 10 may transmit the time synchronization request message at an earlier timing as the node 10 has a smaller number of hops according to the number of hops to the aggregation device 20. For example, each node 10 waits for a time obtained by multiplying the number of hops to the aggregation device 20 by N seconds after power is restored, and then transmits the time synchronization request message. N is a positive number. Thereby, each node 10 is more likely to transmit the time synchronization request message after the time synchronization processing by the parent node is completed, and thus it is possible to prevent the number of times of retransmission of the time synchronization request message from increasing more than necessary.

Note that the node 10 may hold a plurality of identification information of the parent node. For example, when there are a plurality of other nodes 10 having the same number of hops to the aggregation device 20 and the same communication quality of the route, a plurality of identification information of the parent node is held. When multiple identification information of the parent node is held, when it is determined that the time synchronization response message is not returned, for example, when a certain time has elapsed since the time synchronization request message was sent, Alternatively, a time synchronization request message may be transmitted. Further, when no time synchronization response message is returned from any parent node, the operation may be started from the above-described channel scan, that is, the operation of entering the network may be started.

The node 10a that has transmitted the time synchronization request message to the aggregation device 20 receives the time synchronization response message (step S13), and adjusts the time of its own device based on the time information included in the time synchronization response message. Next, the node 10a determines whether or not re-authentication is necessary, that is, whether or not terminal authentication needs to be performed again (step S14). For example, the node 10a determines that re-authentication is necessary when the remaining time until the expiration date of the terminal authentication performed last time is shorter than a predetermined threshold or when the expiration date has already been exceeded. . When the expiration date of terminal authentication ends, the expiration date of the encryption key held in the storage unit 16 also ends. When re-authentication is necessary (step S14: Yes), the node 10a requests the aggregation device 20 to perform terminal authentication of its own device and performs re-authentication (step S15). The terminal authentication operation is as described above. Note that the message processing unit 14 performs processing for determining whether re-authentication is necessary, and the message generation unit 15 performs processing for requesting terminal authentication of the own device to the aggregation device 20. That is, the message processing unit 14 operates as a processing unit that determines whether or not an authentication process for entering the network is necessary. In addition, the message generation unit 15 generates a message requesting the aggregation device 20 to perform authentication processing of its own device. The message generated by the message generation unit 15 is transmitted from the message transmission unit 13 as a transmission unit to the aggregation device 20 as an authentication device. When the terminal authentication is completed, the node 10a updates the encryption key. When re-authentication is not necessary (step S14: No), or when re-authentication ends normally, the node 10a transitions to a state in which a time synchronization request message can be accepted (step S16). Thereafter, the node 10a monitors whether or not a time synchronization request message has been received (step S17). When the node 10a receives the time synchronization request message (step S17: Yes), the node 10a transmits a time synchronization response message including the time information managed by the time management unit 18 to the other node 10 of the request source ( Step S18). When the node 10a does not receive the time synchronization request message (step S17: No), the node 10a continues the monitoring operation. Further, after executing Step S18, the node 10a returns to Step S17 and continues the monitoring operation.

Steps S13 to S18 have been described by taking the case of the node 10a as an example, but the same applies to the

nodes

10b and 10c. However, when the

nodes

10b and 10c determine that re-authentication is necessary in step S14 and perform re-authentication in step S15, the

nodes

10b and 10c perform re-authentication with the aggregation device 20 via the parent node 10a. To do.

Note that the node 10 may perform re-authentication via a node 10 different from the parent node that performed time synchronization. For example, the node 10b may perform re-authentication via the node 10c instead of the parent node 10a.

Since each node 10 operates in accordance with the above procedure, each node 10 does not necessarily need to perform re-authentication after power is restored, so that traffic related to the re-authentication process can be reduced.

Further, each node 10 transitions to a state in which the parent node can accept the time synchronization request message, and determines whether or not re-authentication is necessary after receiving the time synchronization response message from the parent node. Therefore, it is possible to prevent the occurrence of radio resource depletion and radio congestion.

FIG. 7 is a diagram illustrating an example of an operation when the

nodes

10a and 10b synchronize the time with the aggregation device 20. In FIG. 7, the same steps as those shown in FIG. 6 are denoted by the same step numbers.

As shown in FIG. 7, if both the

nodes

10a and 10b determine that re-authentication is required in step S14, first, the node 10a performs re-authentication, and after the re-authentication is completed, The process proceeds to step S16 so that the time synchronization request message can be accepted. Until the re-authentication by the node 10a is completed, the node 10a does not respond to the time synchronization request message transmitted from the node 10b. As a result, the re-authentication timing of the node 10b is distributed from the re-authentication timing of the node 10a.

As described above, according to the present embodiment, in the wireless multi-hop network system having a tree topology, the aggregation device 20 which is the top of the tree responds to the time synchronization request message from the

node

10, 10 determines whether to perform the re-authentication process based on the current time acquired by the time synchronization response message, and skips the re-authentication process when the re-authentication process is unnecessary. Thereby, unnecessary traffic related to the re-authentication process can be reduced, and the time required until encryption communication can be performed again can be shortened.

When the node 10 receives the time synchronization response message from the parent node and determines whether or not re-authentication is necessary after completing the time synchronization processing with the parent node, the node 10 determines that re-authentication is unnecessary Alternatively, since the time synchronization response message is transmitted in response to the time synchronization request message from the other node 10 after the re-authentication is completed, the execution timing of the re-authentication process in the node 10 determined to require re-authentication is distributed. The As a result, wireless congestion can be avoided, message retransmission can be reduced, and the time until encryption communication can be performed again can be shortened.

In the above description, when the node 10 receives a time synchronization request message from another node 10 when power is restored from a power failure, the node 10 transmits a time synchronization response message after completing the determination as to whether re-authentication is necessary. However, the time synchronization response message may be transmitted to the requesting node 10 based on the adjusted time without waiting for the determination of the necessity of re-authentication after completion of the time adjustment processing of the own device.

Embodiment 2. FIG.
In the present embodiment, a case will be described in which the time synchronization request message and the time synchronization response message used in the time synchronization process described in the first embodiment are encrypted and transmitted. The configuration of the wireless multi-hop network system is the same as that shown in FIG. The configurations of the node 10 and the aggregation device 20 are the same as those in FIGS.

In the present embodiment, each node 10 holds a common group key in the storage unit 16, and encrypts the time synchronization request message and the time synchronization response message using the group key. The group key is a common encryption key distributed to nodes that have been successfully authenticated after terminal authentication by the aggregation device 20. Unlike the encryption key that is uniquely held by each node 10 for transmission / reception with the aggregation device 20, the group key does not need to be updated at the end of the terminal authentication expiration date.

In this embodiment, when transmitting the time synchronization request message, the node 10 reads out the group key from the storage unit 16 and encrypts it, and transmits it to the parent node which is the aggregation device 20 or another node 10. When receiving the time synchronization request message, the parent node reads the group key held in the storage unit 26 or 16 and decrypts the time synchronization request message. When the time synchronization request message is successfully decrypted, the parent node encrypts and transmits the time synchronization response message using the same group key after performing necessary processing. When the node 10 receives the time synchronization response message, the node 10 decrypts it using the same group key used for encryption of the time synchronization request message.

When sending the above time synchronization request message, the time synchronization is not completed immediately after power is restored from a power failure, and the current time is unknown. For this reason, when the time synchronization request message is encrypted and transmitted using an encryption key that needs to be updated at the end of the validity period of terminal authentication, it is encrypted if the validity period of the encryption key has expired. The transmitted time synchronization request message is discarded at the parent node. However, the time synchronization request message and the time synchronization response message are encrypted using a common group key that does not require renewal at the end of the validity period of terminal authentication, thereby enabling time synchronization processing at the time of power recovery. .

The group key can have an expiration date different from the expiration date of terminal authentication (the expiration date of the encryption key). In this case, a new group key may be distributed from the aggregation device 20 to each node 10 and updated at a predetermined date and time at each node 10 before a predetermined period of the expiration date of the group key.

In addition to encrypting and transmitting the time synchronization request message and the time synchronization response message, an authentication code called MIC (Message Integrity Check) may be added and transmitted. For example, an encryption method with an authenticator such as AES-GCM (Advanced Encryption Standard Galois / Counter Mode) is applied. When the encrypted information is decrypted, the authenticator confirmation process is also performed to detect the presence or absence of falsification.

As described above, in the present embodiment, since the time synchronization request message and the time synchronization response message are transmitted by being encrypted using the group key, the contents of the message can be concealed and tampering can be detected. In addition, by using a common group key in each terminal, traffic for encryption key sharing that occurs when a parent node is changed due to a change in communication quality, compared to a case where an encryption key that is shared only with the parent node is used. Can be avoided.

Embodiment 3 FIG.
The node 10 according to the first embodiment is configured to hold the identification information of the parent node in the storage unit 16 after selecting the parent node. However, for example, since the quality of the communication path characterized by the strength of the propagated radio signal and the like varies with time, there is no guarantee that the parent node once selected by each node 10 will continue to be optimal after that. It is desirable to review the parent node as necessary. For this reason, for example, the node 10 according to the present embodiment periodically searches for other surrounding nodes 10 and reselects the parent node.

With such a configuration, it is possible to maintain high-quality communication and prevent various messages from being retransmitted. Since the frequency of retransmission of the time synchronization request message and time synchronization response message that are sent and received in the time synchronization process after power recovery can be kept low, the time required until network operation is possible after power recovery It can prevent becoming longer.

In the wireless mesh network system of the first embodiment, the node 10 periodically reviews the parent node. However, in the wireless mesh network system of the second embodiment, the node 10 may periodically review the parent node. .

Embodiment 4 FIG.
In the first embodiment, terminal authentication is performed between the node 10 and the aggregation device 20. However, the aggregation device 20 transfers a message for authentication to the higher-level device, and the higher-level device and the node 10 communicate with each other. It is good also as a structure which performs terminal authentication. FIG. 8 is a diagram illustrating a configuration example of the wireless multi-hop network system according to the present embodiment. The wireless multi-hop network system shown in FIG. 8 includes a plurality of

nodes

10a, 10b, and 10c, an aggregation device 20, and an authentication server 30 that is a server device. In the network system shown in FIG. 8, terminal authentication is performed between the node 10 and the authentication server 30. That is, in this embodiment, the authentication server 30 corresponds to the authentication device.

FIG. 9 is a diagram illustrating a configuration example of the authentication server 30. The authentication server 30 includes a communication unit 32 that transmits and receives signals to and from the aggregation device 20, and a message transmission unit 33 that outputs a message to be transmitted to the node 10 via the aggregation device 20 to the communication unit 32 and requests transmission. A message reception unit 34 that receives a message from the node 10 via the aggregation device 20, a message generation unit 35 that generates a message transmitted by the message transmission unit 33, a storage unit 36 that stores various information, and a message A message processing unit 37 that receives and analyzes a message received by the reception unit 34 and executes an operation according to the analysis result; and a time management unit 38 that receives and holds time information acquired from an external time source. Prepare.

The authentication server 30 performs terminal authentication with each node 10 by performing the same operation as the aggregation device 20 described in the first embodiment. Communication between the authentication server 30 and the aggregation device 20 may be wired communication or wireless communication.

With this configuration, information related to terminal authentication can be centrally managed by the host device, and the aggregation device 20 does not need to have information related to terminal authentication, for example, an authentication key. There is an effect of increasing the ease of. For example, in the case of a system with a plurality of aggregation devices 20, when replacing the aggregation device 20 with a new one due to a failure of the aggregation device 20, it is not necessary to set work related to terminal authentication in the new aggregation device 20. Become. Similarly, when the aggregation device 20 is additionally installed, it is not necessary to set information related to terminal authentication in the additional aggregation device 20.

It should be noted that the operation described in the second embodiment, that is, the operation of encrypting a message to be transmitted / received in the time synchronization process can be applied to the wireless mesh network system of the present embodiment. In addition, the operation described in the third embodiment, that is, the operation in which each node 10 periodically reviews the parent node can be applied. Both the operation described in the second embodiment and the operation described in the third embodiment can be applied.

The hardware configuration of the node 10, the aggregation device 20, and the authentication server 30 described in each embodiment will be described. The node 10, the aggregation device 20, and the authentication server 30 can be realized by, for example, the hardware 100 illustrated in FIG. The hardware 100 includes a processor 101, a memory 102, a clock 103, and a communication device 104.

The processor 101 is a CPU (Central Processing Unit, a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a processor, or a DSP), a system LSI (Large Scale Integration), or the like. The memory 102 is a nonvolatile or volatile semiconductor such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), etc. Memory, magnetic disk, flexible disk, optical disk, compact disk, mini disk, DVD (Digital Versatile Disc), etc.

When the node 10 is realized by the hardware 100, the wireless communication unit 12 of the node 10 is realized by the communication device 104.

Among the components of the node 10, the message transmission unit 13, the message reception unit 14, the message generation unit 15, and the message processing unit 17 are realized by the processor 101 and the memory 102. That is, each component is realized by the processor 101 reading out the program corresponding to each of the message transmission unit 13, the message reception unit 14, the message generation unit 15, and the message processing unit 17 from the memory 102 and executing it.

The storage unit 16 of the node 10 is realized by the memory 102. The time management unit 18 of the node 10 is realized by the clock 103.

When the aggregation device 20 is realized by the hardware 100, the wireless communication unit 22 of the aggregation device 20 is realized by the communication device 104.

Among the components of the aggregation device 20, the message transmission unit 23, the message reception unit 24, the message generation unit 25, and the message processing unit 27 are realized by the processor 101 and the memory 102. That is, each component is realized by the processor 101 reading out the program corresponding to each of the message transmission unit 23, the message reception unit 24, the message generation unit 25, and the message processing unit 27 from the memory 102 and executing it.

The storage unit 26 of the aggregation device 20 is realized by the memory 102. The time management unit 28 of the aggregation device 20 is realized by the clock 103.

When the authentication server 30 is realized by the hardware 100, the communication unit 22 of the authentication server 30 is realized by the communication device 104.

Among the components of the authentication server 30, the message transmission unit 33, the message reception unit 34, the message generation unit 35, and the message processing unit 37 are realized by the processor 101 and the memory 102. That is, each component is realized by the processor 101 reading out the program corresponding to each of the message transmission unit 33, the message reception unit 34, the message generation unit 35, and the message processing unit 37 from the memory 102 and executing the program.

The storage unit 36 of the authentication server 30 is realized by the memory 102. The time management unit 38 of the authentication server 30 is realized by the clock 103.

In addition, although the case where some components of the node 10, the aggregation device 20, and the authentication server 30 are realized by a general-purpose processing circuit including the processor 101 and the memory 102 has been described, these components are realized by a dedicated processing circuit. It is also possible to do. Examples of dedicated processing circuits include FPGA (Field Programmable Gate Array), ASIC (Application Specific Integrated Circuit), single circuit, compound circuit, programmed processor, parallel programmed processor, and the like.

The configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

10a, 10b, 10c node, 11, 21 antenna, 12, 22 wireless communication unit, 13, 23 message transmission unit, 14, 24 message reception unit, 15, 25 message generation unit, 16, 26 storage unit, 17, 27 message Processing unit, 18, 28 Time management unit, 20 aggregation device, 30 authentication server, 41, 51 local destination, 42, 52 local transmission source, 43, 53 message type, 54 time.

Claims

A communication device that is under the control of an aggregation device and forms a tree-like wireless multi-hop network,
Time adjustment means for obtaining time information from the aggregation device or another communication device and adjusting the time of the own device;
After the time adjustment means adjusts the time of the own device, based on the adjusted time of the own device, processing means for determining whether or not an authentication process for entering the wireless multi-hop network is necessary,
When it is determined that the authentication process is necessary, a transmitting unit that transmits a signal requesting the authentication process to an authentication apparatus that determines whether the communication apparatus is an apparatus that can participate in the wireless multi-hop network;
A communication apparatus comprising:
When time information is requested from another communication apparatus, time information transmission means for transmitting the time information of the own apparatus adjusted by the time adjustment means to the other communication apparatus of the request source,
The communication apparatus according to claim 1, further comprising:
When time information is requested from another communication device, the time information transmission means determines whether or not the authentication process is necessary, and then transmits the adjusted time information of the own device to the other communication device of the request source. The communication device according to claim 2, wherein:
An encryption key updating means for updating an encryption key used for encrypted communication with the authentication device when entry to the wireless multi-hop network is permitted by the authentication device;
The communication apparatus according to claim 1, further comprising:
Sharing a group key used for cryptographic communication with other communication devices forming the wireless multi-hop network with the other communication devices;
5. The communication device according to claim 1, wherein the time adjustment unit requests time information from the other communication device by encrypted communication using the group key.
6. The communication device according to claim 1, wherein the time adjustment unit periodically reselects a request destination of time information from the aggregation device and another communication device. .
The communication device according to any one of claims 4 to 6, wherein the expiration date of the encryption key is an authentication expiration date for entering the wireless multi-hop network.
The authentication device is an aggregation device that transmits and receives information to and from the communication device, or a server device that is above the aggregation device and communicates with the communication device via the aggregation device. The communication apparatus according to any one of claims 1 to 7.
An authentication device that exists above a plurality of communication devices forming a tree-shaped wireless multi-hop network and performs an authentication process to determine whether the communication device is a device that can participate in the wireless multi-hop network,
The authentication device includes time information transmission means for transmitting time information to a subordinate communication device,
The subordinate communication device determines whether or not the authentication processing is necessary based on the time information acquired from the authentication device or the time information acquired from another communication device, and performs the authentication processing when it is determined to be necessary. Sending a requesting signal to the authentication device;
The authentication apparatus performs the authentication process on a subordinate communication apparatus that has requested the authentication process.
When it is determined that a communication device under control of the authentication process is a communication device capable of entering the wireless multi-hop network, an encryption key used for encryption communication with the communication device is transmitted to the communication device. The authentication apparatus according to claim 9, wherein
A tree-like wireless multi-hop network composed of a plurality of communication devices, and an authentication process that determines whether the communication device is a device that exists above the communication device and can enter the wireless multi-hop network. A network system comprising an authentication device,
The authentication device includes time information transmission means for transmitting time information to a subordinate communication device,
The communication device determines whether the authentication processing is necessary based on time information acquired from the authentication device or time information acquired from another communication device, and requests the authentication processing if it is determined to be necessary To the authentication device,
The network system, wherein the authentication apparatus performs the authentication process on a subordinate communication apparatus that has requested the authentication process.