COMMUNICATION DEVICE, COMMUNICATION METHOD, AND PROGRAM

Abstract

To efficiently transmit data in a communication network including multiple kinds of communication devices different in the number of available communication systems.SOLUTION: A communication apparatus includes: a network interface which can transmit / receive a telegraphic message through a first communication system which is available in a first communication apparatus and a second communication apparatus in a network, and also through a second communication system which is available in the second communication apparatus; a storage unit which stores 0 or more entries comprising communication addresses of other communication apparatuses and one or more kinds of communication systems available for the other communication apparatuses; and a transmission control unit which transmits, on receipt of first data telegraphic message from arbitrary another communication apparatus, the first data telegraphic message from the network interface, in accordance with a ratio between the first communication system and the second communication system stored in the storage unit, using one of the first communication system and the second communication system.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] An embodiment of the present invention relates to a communication device, a communication method, and a program. [Background technology]

[0002] Conventionally, methods for distributing data from a server or an aggregator to a large number of communication devices in a multi-hop network are known, for example, from Non-Patent Document 1, Non-Patent Document 2, and Patent Document 1. A multi-hop network is also called a mesh network. In addition, an aggregator is also called a border router or a concentrator.

[0003] Conventionally, in a communication network including a plurality of communication devices, a plurality of types of communication devices each having a different number of types of available communication methods may be mixed together due to the introduction of a successor model of a communication device, etc. For example, a successor communication device may be capable of using a new communication method (e.g., OFDM (Orthogonal Frequency Division Multiplexing)) in addition to the communication method (e.g., FSK (frequency shift keying)) available to the current communication device.

[0004] Therefore, for example, when sending data from a server to all communication devices in a communication network, the data can be sent to all communication devices by using a communication method (FSK) that is currently available for communication devices. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2013-556035 A [Non-patent literature]

[0006] [Non-Patent Document 1] ” RPL: ​​IPv6 Routing Protocol for Low-Power and Lossy Networks”, [online], Internet Engineering Task Force (IETF), [Retrieved April 23, 2021], Internet<URL:https: / / tools.ietf.org / html / rfc6550> [Non-Patent Document 2] ” Multicast Protocol for Low-Power and Lossy Networks (MPL)”, [online], Internet Engineering Task Force (IETF), [Retrieved April 23, 2021], Internet<URL:https: / / tools.ietf.org / html / rfc7731> [Non-Patent Document 3] "Trickle Algorithm", [online], Internet Engineering Task Force (IETF), [Retrieved April 27, 2021], Internet<URL:https: / / tools.ietf.org / html / rfc6206> Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the above-mentioned conventional technology, for example, a new communication method (OFDM) that can be used by a successor communication device may be superior in terms of communication speed, etc., to a communication method (FSK) that can be used by a current communication device, and there is room for improvement in terms of data transmission efficiency.

[0008] Therefore, an object of the present invention is to provide a communication device, a communication method, and a program that can efficiently transmit data in a communication network in which multiple types of communication devices with different numbers of usable communication methods are mixed. [Means for solving the problem]

[0009] A communication device of an embodiment includes a network interface capable of sending and receiving messages using either a first communication method usable by a first communication device and a second communication device in a communication network, and a second communication method usable by the second communication device, a memory unit that stores zero or more entries consisting of communication addresses of other communication devices and one or more types of communication methods usable by the other communication devices, and a transmission control unit that, when receiving a first data message from any other communication device, transmits the first data message from the network interface using either the first communication method or the second communication method depending on the ratio of the first communication method and the second communication method stored in the memory unit. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating an overall configuration of a communication system according to an embodiment. [Diagram 2] FIG. 2 is a block diagram illustrating a functional configuration of the communication device according to the embodiment. [Diagram 3] FIG. 3 is a diagram illustrating an information table stored in the storage unit of the communication device of the embodiment. [Figure 4] FIG. 4 is a sequence diagram illustrating the processing of a plurality of communication devices in the communication system according to the embodiment. [Diagram 5] FIG. 5 is a flowchart illustrating a process performed by the communication device according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] A communication device, a communication method, and a program according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

[0012] In order to facilitate understanding of the embodiments, the prior art will be described once again. Take, for example, Internet of Things (IoT) devices such as smart meters and image monitoring systems that configure a mesh network (also called a multi-hop network). Globally, mesh networks of IoT devices such as smart meters are constructed using low-speed frequency shift keying (FSK) of 900 MHz band wireless. A multi-hop network includes a communication device and an aggregation device that can communicate with each other, and a communication device that cannot directly communicate with the aggregation device transfers data by a bucket brigade method via another communication device.

[0013] In addition, the international standard IEEE (Institute of Electrical and Electronics Engineers) 802.15.4 has added OFDM (Orthogonal Frequency Division Multiplexing), a faster wireless method for the 920 MHz band. Many IoT devices use FSK, but there is a demand to shorten the power transmission interval and transmit more data in a multi-hop network.

[0014] For example, when updating firmware for communication devices, distributing firmware, which is a large amount of data, from a server to all communication devices takes time using slow FSK. When high-speed OFDM is available, there is a demand for efficient distribution using OFDM. However, if existing communication devices can only operate with FSK, data must be distributed to those communication devices using FSK.

[0015] Therefore, the following describes a technology that can efficiently transmit data in a communication network that contains multiple types of communication devices with different numbers of available communication methods. More specifically, as an example, the following describes a technology that efficiently distributes data to multiple communication devices under an aggregation device in a mesh network that contains a communication device that operates only with FSK and a newly installed communication device that supports both FSK and OFDM.

[0016] (Embodiment) 1 is a diagram illustrating a schematic diagram of an overall configuration of a communication system S according to an embodiment. The communication system S includes a server 1 and a communication network N. The communication network N is, for example, a wireless multi-hop network. The communication network N includes an aggregation device 2, a plurality of communication devices 3A (second communication devices), and a plurality of communication devices 3B (first communication devices).

[0017] The communication device 3A is a communication device that supports both FSK (first communication method) and OFDM (second communication method). The communication device 3B is a communication device that supports only FSK. Hereinafter, when there is no need to distinguish between the communication device 3A and the communication device 3B, they will be referred to as "communication device 3."

[0018] In the communication network N, a communication path is autonomously constructed according to, for example, the communication standard RPL (IPv6 Routing protocol for Low Power and Lossy Networks). Specifically, each communication device 3 selects a parent node from among the neighboring communication devices 3 according to the quality of wireless communication with the neighboring communication devices 3. Also, a node 12 in the vicinity of the aggregation device 2 can select the aggregation device 2 as a parent node. In the following, when "communication device 3" is described, it may include "aggregation device 2". Also, each of the communication devices 3 may be referred to as "communication device #1", "communication device #2", etc. The communication device 3 is, for example, a smart meter. Note that the arrows between the communication devices 3 in FIG. 1 indicate a parent-child relationship, and two neighboring communication devices 3 may be able to communicate with each other even if they are not in a parent-child relationship.

[0019] The aggregation device 2 and the server 1 are communicatively connected via a WAN (Wide Area Network), which is a wide area communication network such as a mobile phone network or an optical fiber network.

[0020] The server 1 is a computer device, and transmits and receives data to and from each communication device 3 in the communication network N.

[0021] 2 is a block diagram showing a functional configuration of a communication device 3A according to an embodiment of the present invention. The communication device 3A includes a network interface 31, a storage unit 32, and a processing unit 33.

[0022] The network interface 31 is capable of transmitting and receiving messages by FSK and OFDM with nearby communication devices 3 in the communication network N. The network interface 31 can be realized by, for example, a wireless chip or a PLC chip. In other words, the communication network N is not limited to a wireless network, and may be a wired network such as a PLC.

[0023] Furthermore, when the network interface 31 supports both OFDM and FSK, it may be realized by a single network interface, or it may be realized by combining two network interfaces, one that supports only OFDM and one that supports only FSK. Furthermore, the network interface 31 may support another wireless system in addition to FSK and OFDM.

[0024] The storage unit 32 stores various information (various programs, various data) and is realized by, for example, a random access memory (RAM), a read only memory (ROM), a hard disk drive (HDD), etc. The storage unit 32 stores, for example, the communication address of a nearby communication device 3 and the type of communication method (FSK, OFDM) that can be used by the communication device 3. In addition, when a parent-child relationship is set between a plurality of communication devices 3 in the communication network N, the storage unit 32 may store the communication address of a child node communication device 3 among the nearby communication devices 3 and the type of communication method that can be used by the child node communication device 3.

[0025] Here, Fig. 3 is a diagram showing an information table stored in the storage unit 32 of the communication device 3 of the embodiment. As shown in Fig. 3, this information table is composed of zero or more entries. Each entry is linked with a communication address, a usable communication method, and whether or not it is a child node for a nearby communication device 3 (if "True", it is a child node). By referring to this information table, the communication device 3 can recognize the ratio of usable communication methods (FSK and OFDM) for nearby communication devices 3 with which it can communicate, etc.

[0026] In addition, if there is an information table in which only child nodes are registered, or if whether a node is a child node or not is irrelevant to data transfer, information on whether a node is a child node or not is not necessary.

[0027] 2, the processing unit 33 executes various types of arithmetic processing and is realized by, for example, a CPU (Central Processing Unit). The processing unit 33 includes a reception control unit 331 and a transmission control unit 332 as functional units.

[0028] The reception control unit 331 controls reception of data from nearby communication devices 3 using FSK or OFDM.

[0029] The transmission control unit 332 controls data transmission by FSK or OFDM to the nearby communication device 3. For example, when the transmission control unit 332 receives a first data telegram from the nearby communication device 3, the transmission control unit 332 refers to the storage unit 32, selects either FSK or OFDM according to the ratio of FSK and OFDM associated with the stored communication address of the nearby communication device 3, and transmits the first data telegram from the network interface.

[0030] Furthermore, when receiving a second data telegram that is the next data telegram to the first data telegram, the transmission control unit 332 transmits the second data telegram from the network interface after a first time has elapsed if the first data telegram is transmitted by FSK, and transmits the second data telegram from the network interface after a second time, which is shorter than the first time, has elapsed if the first data telegram is transmitted by OFDM.

[0031] Furthermore, when the transmission control unit 332 receives a first data telegram from a nearby communication device 3, the transmission control unit 332 may refer to the storage unit 32, and if all stored entries include OFDM, select OFDM and transmit the first data telegram from the network interface. Conversely, if there is one or more entries that include only FSK, select FSK and transmit the first data telegram from the network interface.

[0032] Next, Fig. 4 is a sequence diagram showing the processing of the multiple communication devices 3 in the communication system S of the embodiment. Fig. 4 also shows a sequence focusing on the operation of communication device #2, among communication devices #1 to #4.

[0033] Communication devices #1, #2, #3, and #4 shown in Fig. 4 correspond to communication device 3A (#1), communication device 3A (#2), communication device 3A (#3), and communication device 3B (#4) shown in Fig. 1. That is, communication devices #1 to #3 shown in Fig. 4 are communication devices that can use both FSK and OFDM communication methods, and communication device #4 is a communication device that can use only FSK.

[0034] First, in step S1, communication device #2 transmits a first control message by multicast. The first control message reaches communication device #1 and communication device #3.

[0035] Next, in step S2, communication device #1 transmits a second control message to communication device #2, and in step S3, communication device #3 transmits the second control message to communication device #2. The first control message and the second control message include information such as the sender address (communication address) and the type of communication method that the sender communication device can use. Note that the control message transmitted by communication device #2 is referred to as the first control message, the control message received by communication device #2 is referred to as the second control message, and the other control messages are referred to as the third control messages.

[0036] Since communication devices #1 to #3 support OFDM and FSK, information indicating OFDM and FSK is described in the first control message and the second control message transmitted in steps S1 to S3.

[0037] Next, in step S4, communication device #1 transmits a multicast packet to communication device #2. Next, in step S5, communication device #2 transfers the multicast packet (first data message) to communication device #3 by OFDM.

[0038] Next, in step S6, communication device #1 transmits a multicast packet to communication device #2. Next, in step S7, communication device #2 transfers the multicast packet (second data message) to communication device #3 by OFDM after T1 (a second time shorter than T2 (first time) described later) has elapsed since step S5.

[0039] Here, it is assumed that communication device #4, which supports only FSK, is started up and participates in communication network N in step S8.

[0040] Next, in step S9, communication device #4 transmits a third control message. The third control message reaches communication device #2 and communication device #3. Since communication device #4 is a communication device that can use only FSK, the third control message contains information indicating FSK, but does not contain information indicating OFDM.

[0041] Furthermore, in step S10, communication device #4 transmits a Neighbor Solicitation (NS) with an Address Registration Option (ARO). The NS with ARO arrives at communication device #2 and communication device #3. The child node transmits the NS with ARO to the parent node, allowing the parent node to hold a list of child nodes. Note that the transmission of the NS with ARO may be performed prior to the transmission of the third control message in step S9, and the timing is not limited to the example in FIG. 4.

[0042] Next, in step S11, communication device #1 transmits a multicast packet. Next, in step S12, communication device #2 transfers the multicast packet (first data message) using FSK, which reaches communication device #3 and communication device #4.

[0043] Next, in step S13, communication device #1 transmits a multicast packet. Next, in step S14, communication device #2 transfers the multicast packet (second data message) by FSK after T2 (first time) has elapsed since step S12, and the packet reaches communication device #3 and communication device #4.

[0044] Next, Fig. 5 is a flowchart showing the process by the communication device 3 of the embodiment. For example, the process shown in Fig. 5 is executed by the communication device #2 in Fig. 4 in the following cases (1) to (7). (1) When the second control message is received in steps S2 and S3 (2) When a multicast packet is received in step S4 and then forwarded in step S5 (3) When a multicast packet is received in step S6 and then forwarded in step S7 (4) When a multicast packet is received in step S11 and the multicast packet is forwarded in step S12 (5) When a multicast packet is received in step S13 and then forwarded in step S14 (6) When the third control message is received in step S9 (7) When NS with ARO is received in step S10

[0045] In step S101, the receiving control unit 331 of the communication device 3 determines the type of message received from a neighboring communication device 3, and if it is a control message, proceeds to step S102; if it is a multicast packet, proceeds to step S103; and if it is NS with ARO, proceeds to step S104.

[0046] In step S102, the reception control unit 331 stores the source address and the communication method written in the control message in the storage unit 32 (FIG. 3).

[0047] In step S103, the transmission control unit 332 refers to the information table in the memory unit 32 (Figure 3) and determines whether the proportion of OFDM-compatible nearby communication devices 3 with which communication is possible is greater than a predetermined threshold value R1. If the answer is Yes, the process proceeds to step S105; if the answer is No, the process proceeds to step S107.

[0048] If the transmission control unit 332 determines in step S105 that this is the second or subsequent transmission of the multicast packet, then it waits a time T1 from the previous transmission, and then transmits the multicast packet by OFDM in step S106.

[0049] If the transmission control unit 332 determines in step S107 that this is the second or subsequent transmission of the multicast packet, then it waits a time T2 from the previous transmission, and then transmits the multicast packet in FSK in step S108.

[0050] In step S104, the reception control unit 331 saves a value indicating that the communication device 3 of the source address of the ARO-added NS is a child node ("True" in the example of FIG. 3).

[0051] In this way, according to the communication device 3 of this embodiment, data transmission can be performed efficiently by selectively using FSK and OFDM for the multicast packets to be forwarded depending on the proportion of communication methods (FSK only, or FSK and OFDM) available to neighboring communication devices 3.

[0052] In addition, by varying the length of the interval time until the second and subsequent transfers, data transmission can be performed more efficiently.

[0053] Note that time T1 only needs to be shorter than time T2 on average, and time T1 may be longer than time T2 in some cases, and time T1 and time T2 do not need to be constant. For example, by using the Trickle algorithm shown in Non-Patent Document 3 to make Imin and Imax of a timer for transmitting multicast packets by OFDM shorter than Imin and Imax of a timer for transmitting by FSK, time T1 can be made shorter than time T2 on average.

[0054] Also, for example, if OFDM is used when there is no nearby communication device 3 that supports only FSK, and FSK is used when there is at least one nearby communication device 3 that supports only FSK, the communication device 3 that supports only FSK can also receive data.

[0055] In addition, the communication device 3 to which the data is forwarded may be limited to a child node.

[0056] The program for executing the above-mentioned processes in the above-mentioned embodiment may be provided by recording it in an installable or executable format on a computer-readable recording medium such as a CD-ROM, a flexible disk (FD), a CD-R, a digital versatile disk (DVD), or a universal serial bus (USB) 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 structure including each functional unit, and as actual hardware, for example, a CPU (processor circuit) reads the program from a ROM or HDD and executes it, whereby each of the above-mentioned functional units is loaded onto a RAM (main memory) and generated on the RAM (main memory). Note that it is also possible to realize some or all of the above-mentioned functional units using dedicated hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array).

[0058] Although the embodiment has been described above, the embodiment is presented as an example and is not intended to limit the scope of the invention. The novel embodiment can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. The above embodiment is included in the scope and gist of the invention, and is included in the scope of the invention and its equivalents described in the claims.

[0059] For example, in the above embodiment, the description has been given mainly of software distribution, but the present invention is not limited to this and can also be applied to a case where a large amount of data is distributed to a large number of communication devices 3. [Explanation of symbols]

[0060] 1: server, 2: aggregation device, 3: communication device, 31: network interface, 32: storage unit, 33: processing unit, 331: reception control unit, 332: transmission control unit, S: communication system

Claims

1. a network interface capable of transmitting and receiving messages using either a first communication method usable by a first communication device and a second communication device in a communication network, and a second communication method usable by the second communication device; a storage unit that stores zero or more entries each including a communication address of another communication device and one or more types of communication methods that the other communication device can use; a transmission control unit that, when receiving a first data telegram from any other communication device, transmits the first data telegram from the network interface using either the first communication method or the second communication method in accordance with a ratio of the first communication method and the second communication method stored in the storage unit; A parent-child relationship is established between the plurality of communication devices, The transmission control unit transmits the first data message from the network interface using either the first communication method or the second communication method, depending on the ratio of entries including the communication addresses of other communication devices that are child nodes and the first communication method to entries including the communication addresses of other communication devices that are child nodes and the second communication method.

2. The transmission control unit When a second data message that is a data message subsequent to the first data message is received, if the first data message is transmitted by the first communication method, transmitting the second data message from the network interface after a first time has elapsed; 2. The communication device according to claim 1, wherein when the first data message is transmitted using the second communication method, the second data message is transmitted from the network interface after a second time period shorter than the first time period has elapsed.

3. The transmission control unit When the first data message is received from the other communication device, the storage unit is referred to; when all of the communication methods associated with all of the stored communication addresses include the second communication method, selecting the second communication method and transmitting the first data message from the network interface; 2. The communication device according to claim 1, wherein when one or more entries including only the first communication method are stored in the memory unit, the first communication method is selected and the first data message is transmitted from the network interface.

4. A communication method for a communication device comprising: a network interface capable of transmitting and receiving a message using either a first communication method usable by a first communication device and a second communication device in a communication network, and a second communication method usable by the second communication device; and a storage unit that stores zero or more entries each consisting of a communication address of another communication device and one or more types of communication methods usable by the other communication device, a transmission control step of, when receiving a first data telegram from any other communication device, transmitting the first data telegram from the network interface using either the first communication method or the second communication method in accordance with a ratio of the first communication method and the second communication method stored in the storage unit; A parent-child relationship is established between the plurality of communication devices, The communication method, wherein the transmission control step transmits the first data message from the network interface using either the first communication method or the second communication method depending on a ratio between an entry including a communication address of another communication device that is a child node and the first communication method, and an entry including a communication address of another communication device that is a child node and the second communication method.

5. A program to be executed by a computer that is a communication device including a network interface capable of transmitting and receiving a message using either a first communication method usable by a first communication device and a second communication device in a communication network, and a second communication method usable by the second communication device, and a storage unit that stores zero or more entries each consisting of a communication address of another communication device and one or more types of communication methods usable by the other communication device, The computer, a program for causing the device to function as a transmission control unit that, when receiving a first data telegram from any other communication device, transmits the first data telegram from the network interface using either the first communication method or the second communication method in accordance with a ratio of the first communication method and the second communication method stored in the storage unit; A parent-child relationship is established between the plurality of communication devices, The transmission control unit transmits the first data message from the network interface using either the first communication method or the second communication method, depending on a ratio of entries including a communication address of another communication device that is a child node and the first communication method to entries including a communication address of another communication device that is a child node and the second communication method.

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