Communication device, communication method, and program

Abstract

To facilitate partial migration to wireless communication for an existing system connected to a wired LAN environment.SOLUTION: A communication device includes a wired communication interface connected to an external device via a wired network, a wireless communication interface connected to other communication devices via a wireless network, and a processing unit. The processing unit includes a relay unit that relays data communication from the wired communication interface and data communication from the wireless communication interface, and a determination unit that determines whether data communication relay by the relay unit is possible.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] FIELD Embodiments of the present invention relate to a communication device, a communication method, and a program. [Background technology]

[0002] Two communication devices may communicate by being connected via a wired or wireless connection, or a combination of both. For example, the IEEE (Institute of Electrical and Electronics Engineers) 802.3 Ethernet (registered trademark) standard imposes limitations on the length of LAN (Local Area Network) cables that can communicate. Therefore, when laying LAN cables over a wide area, relay devices such as repeaters are required, and extending the LAN cables also entails the problem of the heavy construction work required for laying and constructing them.

[0003] On the other hand, in recent years, specific low-power radio signals using the 920 MHz band have become available, and there are high expectations for their use in long-distance wireless communications that do not require the construction and installation work required. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] "IEEE Standard for Local and Metropolitan Area Networks--Part 15.4: Low-Rate Wireless Personal Area Networks (LR-WPANs)," in IEEE Std 802.15.4-2011 Summary of the Invention [Problem to be solved by the invention]

[0005] Here, we consider partially migrating existing systems connected to a wired LAN environment to wireless communication. If partial migration to wireless communication is possible, the burden of laying and constructing the LAN cable extension will be eliminated, and wireless networks will enable a high degree of freedom in physical layout.

[0006] On the other hand, it generally requires the burden of modifying each device that was previously connected via LAN cable to equip it with a new wireless communication interface.In addition, there are cases where the hardware and software configuration of existing devices cannot be changed due to certain restrictions (such as physical restrictions), which may lead to the burden of migration, such as replacing the device itself.

[0007] Therefore, an object of the present invention is to provide a communication device, a communication method, and a program that can easily migrate part of an existing system connected to a wired LAN environment to wireless communication. [Means for solving the problem]

[0008] According to an embodiment, a communication device includes a wired communication interface connected to an external device via a wired network, a wireless communication interface connected to another communication device via a wireless network, and a processing unit, wherein the processing unit includes a relay unit that relays data communication of the wired communication interface and data communication of the wireless communication interface, and a determination unit that determines whether the relay unit can relay the data communication. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing the overall configuration of a communication system according to an embodiment. [Figure 2] FIG. 2 is a functional configuration diagram of the communication device according to the embodiment. [Figure 3] FIG. 3 is a diagram illustrating an example of the operation of the communication system according to the embodiment. [Figure 4] FIG. 4 is a diagram illustrating an example of the operation of the communication system according to the embodiment. [Figure 5] FIG. 5 is an explanatory diagram of the prior art. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of a communication device, a communication method, and a program according to the present invention will be described in detail with reference to the accompanying drawings.

[0011] To facilitate understanding of the embodiments, the prior art will be explained again. FIG. 5 is an explanatory diagram of the prior art. As shown in FIG. 5, consider a case where external device A and external device B communicate with each other. In this case, assume that a LAN cable 8 is connected to external device A and a LAN cable 9 is connected to external device B, but no LAN cable is laid in area R. In this case, as described above, laying and extending a LAN cable is difficult due to reasons such as cost and certain constraints. Therefore, the following describes a technology that can easily migrate part of an existing system connected to a wired LAN environment to wireless communication.

[0012] 1 is a diagram showing the overall configuration of a communication system S according to an embodiment. The communication system S includes an external device A, an external device B, a communication device C, and a communication device D. The external device A and the external device B communicate with each other and transmit and receive data. For example, the external device B is a smart meter that acquires and transmits measurement information on a predetermined physical quantity (e.g., electricity usage, gas usage, water usage, etc.), and the external device A is a server that collects and manages information from the smart meter. However, the external devices A and B are not limited to these and may be any communication devices that can communicate via a wired connection such as a LAN cable.

[0013] Communication device C and communication device D are devices that are introduced when it is difficult to lay or extend a LAN cable between external device A and external device B, as in the case of Figure 5, for example. Communication device C and communication device D are connected via wireless communication rather than wired communication. As a communication medium for wireless communication, for example, a specified low-power radio using the 920 MHz band, which has recently become available as an unlicensed band in Japan, is used. As a result, the burden of laying and constructing a conventional wired LAN cable is no longer necessary, and wireless networking allows for a highly flexible physical layout.

[0014] Furthermore, the 920 MHz band communication medium is superior to the 2.4 GHz and 5 GHz band communication media used by Wi-Fi (registered trademark) and Bluetooth (registered trademark), in terms of long-distance communication, and has the advantage of enabling the construction of networks in wider physical locations or in physical locations with large propagation losses due to obstructions, etc.

[0015] Furthermore, by configuring external devices A and B to be connected wirelessly using communication devices C and D rather than connecting them only with a wired LAN cable, the burden of modifying or replacing external devices A and B can be eliminated.

[0016] Furthermore, communication device C and communication device D relay data communications on the wired LAN using wireless communications. The relaying method uses an Ethernet frame format that includes the source MAC (Media Access Control) address and the destination MAC address. As a result, it is possible to provide transparent communications without requiring existing devices (external devices A and B) to be aware of the presence of communication devices C and D. This has the advantage of eliminating the need to change the communication methods (Transmission Control Protocol (TCP) communication method, User Datagram Protocol (UDP) communication method, one-way / two-way communication, end-to-end communication, etc.) or communication settings (Internet Protocol (IP) address, IP version, port number settings, etc.) of the existing devices.

[0017] Next, details of the communication devices C and D will be described. Since the communication devices C and D have the same configuration, the communication device C will be described as a representative example. Fig. 2 is a functional configuration diagram of the communication device C according to the embodiment.

[0018] The communication device C includes a processing unit 1, a wired communication interface 2, and a wireless communication interface 3.

[0019] The wired communication interface 2 is configured by, for example, an IC (Integrated Circuit) chip, and is connected to an external device A via a LAN cable 8 (wired network).

[0020] The wireless communication interface 3 is configured by, for example, an IC (Integrated Circuit) chip, and is connected to a communication device D (another communication device) via a wireless network.

[0021] The processing unit 1 is configured by, for example, a CPU (Central Processing Unit) and a memory, and includes a relay unit 11, a determination unit 12, a management unit 13, and a notification unit 14 as functional units.

[0022] The relay unit 11 relays data communication between the wired communication interface 2 and the wireless communication interface 3 .

[0023] The determining unit 12 determines whether the relay unit 11 can relay the data communication. The management unit 13 manages the quality of wireless communication through the wireless communication interface 3 .

[0024] The notification unit 14 notifies the external device A of the wireless communication quality managed by the management unit 13 via the wired communication interface 2.

[0025] Next, an example of the operation of the communication system S will be described with reference to Fig. 3 and Fig. 4. Fig. 3 and Fig. 4 are diagrams showing an example of the operation of the communication system S according to the embodiment.

[0026] First, referring to Figure 3(a), a case where communication device C and communication device D are installed and initially connected will be described. An installation worker installs communication device C and communication device D, connects external device A and communication device C with LAN cable 8, and connects external device B and communication device D with LAN cable 9. At this time, a configuration is shown in which the external device and communication device are directly connected with a LAN cable, but a configuration in which they are connected via a Layer 2 switch or Layer 2 hub is also acceptable. The wired LAN environments to which external device A and external device B are respectively connected are not connected by wire, and instead of performing construction work to extend or lay wired LAN cables, communication devices C and D are introduced and connected wirelessly.

[0027] Next, the installation worker turns on the power of communication device C and communication device D ( <1> <2> At this time, communication device C and communication device D maintain the state of the wired communication interface 2 as a link down state.

[0028] Next, communication device C and communication device D, which have been turned on, start a wireless connection according to a predetermined procedure ( <3> ) In this case, the predetermined procedure assumes that communication device C and communication device D are compliant with the IEEE802.15.4 standard and connect in accordance with the IEEE802.15.4 standard. For example, communication device C is the master station and communication device D is the slave station, and the slave station detects a beacon signal periodically transmitted by the master station and establishes a connection association with the master station.

[0029] Next, after the communication device C and the communication device D complete the wireless connection with each other, the communication device C and the communication device D change the state of the wired communication interface 2 to the link up state ( <4> ) After this, the wired communication interface 2 connected to external device A and external device B will be in a link-up state, and data communication between external devices A and B can be started (or resumed) in the operation sequence after the existing link-up state ( <5> ).

[0030] Next, with reference to Fig. 3(b), a description will be given of the flow of relaying communication data transmitted from external device A to external device B. As described above, communication device C and communication device D have relay units 11 that relay data communication between wired communication interface 2 and wireless communication interface 3. Relay unit 11 relays communication data received at wired communication interface 2 to wireless communication interface 3, and relays communication data received at wireless communication interface 3 to wired communication interface 2.

[0031] The wired communication interface 2 complies with the IEEE802.3 standard for Ethernet, and the wireless communication interface 3 complies with the IEEE802.15.4 standard for 920 MHz band wireless communication.

[0032] First, external device A sends communication data addressed to external device B in an Ethernet frame (symbol F1). At this time, the MAC address of external device A is set as the source MAC address, and the MAC address of external device B is set as the destination MAC address. Similarly, the IP address of external device A is set as the source IP address, and the IP address of external device B is set as the destination IP address.

[0033] Next, communication device C receives the Ethernet frame (symbol F1) sent by external device A via wired communication interface 2 ( <6> ), and the decision unit 12 decides that it should be transmitted because it is an IP packet ( <7> ), and relayed to the wireless communication interface 3 by the relay unit 11. At this time, since relaying unnecessary Ethernet frames may strain wireless resources, for example, the determination unit 12 narrows down the relaying to only Ethernet frames that are necessary for operation. In this way, unnecessary strain on wireless resources can be avoided.

[0034] For example, it is generally desirable to transfer only Layer 3 packets (such as IPv4, IPv6, ARP, and ND), and it is not necessary to transfer Layer 2 packets (such as STP frames of the IEEE802.1d standard). As an example, the determination unit 12 may determine that data can be relayed if it is an IPv4 packet or an IPv6 packet. Furthermore, in a network managed so that the communication destination of external device A is external device B only, the Ethernet frame may be relayed only if its destination MAC address is external device B.

[0035] Furthermore, communication device C does not change the content of the format of the Ethernet frame (reference symbol F1) containing the source MAC address and destination MAC address received via the wired communication interface 2. Specifically, without changing the content of the received Ethernet frame (reference symbol F1), it sets the MAC address of its own communication device C in the source MAC address and the MAC address of communication device D in the destination MAC address as the MAC header of the IEEE802.15.4 standard (reference symbol F2), and transmits the frame to communication device D via the wireless communication interface 3 (reference symbol F3). <8> ).

[0036] There are several standards for the MAC payload following the MAC header in the IEEE 802.15.4 standard, and the frame structure in which an Ethernet frame follows the MAC header may be unique to this embodiment. Therefore, in other systems that adopt the IEEE 802.15.4 standard, there is a possibility that abnormal processing may occur when receiving and processing data with code F2. Therefore, to avoid such abnormal processing, an ID (Identifier) ​​indicating that the content following the MAC header is Ethernet may be uniquely defined and set in the MPX-IE (Multiplex Information Element). As a result, other systems can refer to the ID in the MPX-IE and transmit and receive only MAC frames related to their own system.

[0037] Next, communication device D receives the MAC frame (symbol F2) conforming to the IEEE802.15.4 standard transmitted by communication device C ( <9> At this time, the MAC address of the communication device C is set as the source MAC address of the MAC frame (symbol F2), and the MAC address of the communication device D is set as the destination MAC address, so the determination unit 12 determines that the frame can be received by the wireless communication interface 3 and can be relayed to the wired communication interface 2. In addition, the determination unit 12 determines that the frame should be transmitted because it is an IP packet ( <10> ).

[0038] Next, in communication device D, relay unit 11 removes the MAC header from the MAC frame (symbol F2) conforming to the IEEE802.15.4 standard received by wireless communication interface 3, and transmits it as an Ethernet frame (symbol F3) to wired communication interface 2. Here, since the contents of the Ethernet frame (symbol F3) to be transmitted have not been changed by communication device C, as described above, the MAC address of external device A is set as the source MAC address, and the MAC address of external device B is set as the destination MAC address.

[0039] In addition, in the process of relaying data communication from the wireless communication interface 3 to the wired communication interface 2 by the relay unit 11 in the communication device D, the relay may be limited to only Ethernet frames that are necessary for operation. For example, similar to the narrowing down in the relay process of the communication device C described above, the transfer may be limited to only Layer 3 packets, or only communications from the external device A, or only communications addressed to the external device B, etc.

[0040] Next, external device B receives the Ethernet frame (reference symbol F3) sent by communication device D. At this time, the content of the received Ethernet frame (reference symbol F3) is the same as the content of the Ethernet frame (reference symbol F1) sent by external device A (that is, it has not been changed in the process of being relayed by communication device C and communication device D). Therefore, the MAC address of external device A is set as the source MAC address, and the MAC address of external device B is set as the destination MAC address. Therefore, external device B can receive the frame because its own MAC address is set as the destination MAC address.

[0041] In this way, external device B can receive an Ethernet frame sent by external device A. External devices A and B can communicate data with each other using transparent communication, which does not require them to be aware of the presence of communication devices C and D. Therefore, communication devices C and D can be applied to the installation environment of existing devices without changing the communication method (TCP communication method, UDP communication method, one-way / two-way communication, end-to-end communication, etc.) or communication settings (IP address, IP version, port number setting, etc.) of the existing devices.

[0042] Next, referring to Fig. 4, a case where wireless transmission failure occurs in wireless communication between communication device C and communication device D is described. The quality of wireless communication between communication device C and communication device D varies depending on the surrounding physical environment, etc. Causes of wireless transmission failure include, for example, a shadowing phenomenon in which direct waves are blocked due to changes in the installation positions of surrounding devices, reducing the reception strength, and a multipath fading phenomenon in which reception quality is reduced due to the influence of reflected waves.

[0043] If radio transmission failure occurs due to these causes ( <11> ), the success rate of receiving MAC frames sent and received by communication device C and communication device D decreases. As a result, the possibility of necessary data communication being lost increases, which may develop into an operational failure.

[0044] Generally, in wireless communication standards, when the loss rate of wireless communication becomes high, the established association is disconnected and the state transitions to a state in which reconnection and searching for other connection destinations are repeated. The management unit 13 of the communication device C, for example, detects and manages the state of wireless communication disconnection. As a method of detecting wireless communication disconnection, for example, in the IEEE802.15.4 standard, the reception status of a beacon signal broadcast at a fixed interval is used as an indicator, and five consecutive losses are detected as a disconnection condition. In other words, the management unit 13 determines that a wireless transmission failure has occurred when the number of consecutive losses of a beacon signal received from the communication device D by the wireless communication interface 3 reaches a predetermined threshold (for example, five times). <12> ).

[0045] Also, instead of receiving a beacon signal, for example, communication device C may periodically transmit a reach confirmation signal to communication device D, and communication device C may receive a response signal from communication device D. In this case, for example, the management unit 13 of communication device C determines that a wireless transmission failure has occurred when the number of consecutive missing response signals from communication device D received via wireless communication interface 3 reaches a predetermined threshold (for example, five times).

[0046] In addition, whether a beacon signal or a confirmation signal and a response signal is used, The threshold value may be fixed, for example, or may be configurable by a remote command from the external device A.

[0047] Furthermore, when the management unit 13 determines that a wireless transmission failure has occurred, the notification unit 14 puts the wired communication interface 2 into a link-down state ( <13> ) Furthermore, even while the notification unit 14 keeps the wired communication interface 2 in a link-down state, the management unit 13 manages the wireless communication quality of the wireless communication interface 3. Furthermore, when the management unit 13 determines that the wireless transmission failure has been recovered from, the notification unit 14 puts the wired communication interface 2 in a link-up state. These will be described in detail below.

[0048] When the management unit 13 of the communication device C detects that the wireless communication has been disconnected, the notification unit 14 transitions the Ethernet link state of the wired communication interface 2 to a link down state. External device A and communication device C control the link state by constantly exchanging electrical pulses through the LAN cable 8, and when communication device C transitions to a link down state, external device A also transitions to a link down state. As a result, when a wireless transmission failure occurs between communication device C and communication device D, external device A can recognize that communication with external device B is not possible.

[0049] Schemes for monitoring Ethernet link status are standardized in standards such as SNMP (Simple Network Management Protocol) and MIB (Management Information Base), and many existing devices already have monitoring schemes in place. Therefore, this method, which recognizes wireless communication disconnection by transitioning the Ethernet link status to link down, eliminates the transition burden of modifying or replacing existing devices, providing cost advantages.

[0050] Furthermore, when the management unit 13 of the communication device C detects that the wireless communication has been restored to a connected state, the notification unit 14 transitions the Ethernet link state of the wired communication interface 2 to a link-up state. When the communication device C transitions to the link-up state, the external device A also transitions to the link-up state. As a result, when the wireless transmission failure between the communication device C and the communication device D is resolved, the external device A can recognize that communication with the external device B has become possible.

[0051] Furthermore, external device A is expected to support the analysis of the causes of wireless transmission failures by recording the Ethernet link status over time and managing statistical fluctuation trends. Generally, data communication by applications is performed intermittently and at low frequency, and failure analysis based solely on data communication loss status makes it difficult to distinguish between a communication device failure that causes a steady link down and the occurrence of a wireless transmission failure that causes an intermittent link down. Monitoring the link status, which accurately reflects the timing of wireless disconnection and recovery, has the advantage of enabling more detailed failure analysis.

[0052] Although this embodiment shows a method of notifying external devices A and B through the Ethernet link status, a method of notifying the status of wireless communication using a different application communication may also be adopted. This method may require modification or replacement of existing devices to support application communication, but it makes it possible to independently define and notify the status of wireless communication, allowing the administrators of external devices A and B to grasp more detailed information.

[0053] As described above, according to the communication system S of this embodiment, by using the communication devices C and D each having the processing unit 1, the wired communication interface 2, and the wireless communication interface 3, it is possible to easily migrate part of an existing system connected to a wired LAN environment to wireless communication. This eliminates the need for the construction work required for laying and constructing conventional wired LAN cables, and enables the construction of a network with a highly flexible physical layout due to the shift to wireless communication. Furthermore, it is possible to eliminate the migration burden of modifying or replacing existing devices.

[0054] Furthermore, as a method for relaying data communications on a wired LAN via a wireless communication interface, a method is adopted in which the contents of Ethernet frames, including the source MAC address and destination MAC address, are relayed without being changed. As a result, it becomes possible to provide transparent communications to existing devices (external devices A and B) without the need to be aware of the presence of communication devices C and D. This has the advantage of eliminating the need to change the communication method (TCP communication method, UDP communication method, one-way / two-way communication, end-to-end communication, etc.) or communication settings (IP address, IP version, port number settings, etc.) of existing devices.

[0055] In addition, by linking the link down state and link up state of the wired communication interface 2 according to the state of the communication quality of the wireless communication, it becomes possible to grasp and manage the communication quality within the existing communication quality management framework of the existing devices (external devices A and B).

[0056] The program for executing the above-described processing in the above-described embodiment may be provided by being recorded in an installable or executable file format on a computer-readable recording medium such as a CD-ROM, a flexible disk (FD), a CD-R, a DVD (Digital Versatile Disc), or a USB (Universal Serial Bus) memory. The program may also be provided or distributed via a network such as the Internet. The program may also be provided by being pre-installed in a ROM or the like.

[0057] The program has a modular configuration including the units 11 to 14 in the processing unit 1, and in actual hardware, for example, a CPU (processor circuit) reads the program from a ROM and executes it, thereby loading the units 11 to 14 into a RAM (main memory) and generating them in the RAM (main memory). Note that some or all of the functions of the units 11 to 14 can also be realized using dedicated hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array).

[0058] Although the embodiments have been described, the above embodiments are presented as examples and are not intended to limit the scope of the invention. The above novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. The above embodiments are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as defined in the claims. [Explanation of symbols]

[0059] 1...processing unit, 2...wired communication interface, 3...wireless communication interface, 11...relay unit, 12...determination unit, 13...management unit, 14...notification unit

Claims

1. A communication device comprising: a wired communication interface connected to an external device via a wired network; a wireless communication interface connected to another communication device via a wireless network; and a processing unit, The processing unit a relay unit that relays data communication between the wired communication interface and the wireless communication interface; a determination unit that determines whether or not the relay unit can relay data communication.

2. The wired communication interface complies with the IEEE 802.3 standard; The communication device according to claim 1 , wherein the wireless communication interface complies with the IEEE 802.15.4 standard.

3. The communication device according to claim 1 , wherein the relay unit relays data communication in an Ethernet frame format including a destination MAC address and a source MAC address.

4. 4. The communication device according to claim 3, wherein when the relay unit receives an Ethernet frame from the external device via the wired communication interface, the relay unit does not change the contents of the Ethernet frame, but sets the MAC address of the communication device itself as the source MAC address and the MAC address of the other communication device as the destination MAC address in the MAC header of the IEEE 802.15.4 standard, and transmits the frame to the other communication device via the wireless communication interface.

5. The communication device according to claim 4, wherein the relay unit sets the MAC header of the IEEE 802.15.4 standard for the Ethernet frame, and sets an ID (Identifier) ​​in an MPX-IE (Multiplex Information Element) indicating that the content following the MAC header is an Ethernet frame, and transmits the frame to the other communication device via the wireless communication interface.

6. 2. The communication device according to claim 1, wherein the determining unit determines that the data can be relayed if the data is an IPv4 packet or an IPv6 packet.

7. a management unit that manages wireless communication quality of the wireless communication interface; The communication device according to claim 1 , wherein the management unit determines that a wireless transmission failure has occurred when the number of consecutive missing beacon signals received from the other communication device via the wireless communication interface reaches a predetermined threshold.

8. a management unit that manages wireless communication quality of the wireless communication interface; The communication device according to claim 1, wherein the management unit determines that a wireless transmission failure has occurred when the number of consecutive missing response signals from the other communication device to an arrival confirmation signal received via the wireless communication interface and periodically transmitted from the communication device to the other communication device reaches a predetermined threshold.

9. 9. The communication device according to claim 7, wherein the threshold value can be changed by a remote command from the external device.

10. a notification unit that notifies the external device of the wireless communication quality managed by the management unit via the wired communication interface; 9. The communication device according to claim 7, wherein the notification unit sets the wired communication interface to a link-down state when the management unit determines that a wireless transmission failure has occurred.

11. The communication device according to claim 10 , wherein the management unit manages the wireless communication quality of the wireless communication interface even while the notification unit is putting the wired communication interface into a link down state.

12. The communication device according to claim 11 , wherein the notification unit sets the wired communication interface to a link-up state when the management unit determines that the wireless transmission failure has been recovered.

13. A communication method for a communication device including a wired communication interface connected to an external device via a wired network, a wireless communication interface connected to another communication device via a wireless network, and a processing unit, the method comprising: Executed by the processing unit: a relay step of relaying data communication between the wired communication interface and the wireless communication interface; a determination step of determining whether or not the data communication can be relayed by the relay step.

14. A computer serving as a processing unit in a communication device including a wired communication interface connected to an external device via a wired network, a wireless communication interface connected to another communication device via a wireless network, and a processing unit, a relay unit that relays data communication between the wired communication interface and the wireless communication interface; A program for causing the relay unit to function as a determination unit that determines whether or not the relay unit can relay data communication.

Images