JP6384792B2 - Communications system - Google Patents

Description

The present invention generally relates to communication systems, and more particularly, relates to a communication system for performing power line communication between a master unit and a plurality of slave unit.

  Conventionally, as this type of communication system, a single master unit and a plurality of slave units connected to the same distribution line are provided for each network, and a distribution line is provided between the master unit and the slave units in each network. A system that performs power line carrier communication used for a transmission medium is known. However, when a plurality of networks for power line carrier communication are constructed, the communication of any one network may interfere with the communication of one or a plurality of other networks due to its characteristics.

  For example, Patent Document 1 describes a technique for suppressing communication interference that occurs between a plurality of networks in this type of communication system. That is, in the configuration described in Patent Document 1, the communication device that is the parent device transmits a command communication signal to other communication devices to adjust the transmission output level. When receiving the command communication signal, the communication device controls the transmission output level so that the communication signal is transmitted with the minimum communication quality that allows communication with another communication device adjacent on the communication.

JP 2010-273275 A

  However, in the above conventional example, the master unit adjusts the transmission output level of other communication devices by transmitting a command notification signal regardless of whether communication interference actually occurs with other networks. To do. For this reason, there is a possibility that the transmission output level is suppressed even in a communication apparatus that cannot cause communication interference with other networks. That is, in the above conventional example, there is a possibility that control for suppressing interference is performed until there is no problem in communication between different networks.

The present invention has been made in view of the above, and aims to provide a communication system is not the control is performed to suppress interference to when there is no trouble in communication between different networks To do.

The communication system according to the present invention includes a plurality of networks each including one master unit and a plurality of slave units connected to the same distribution line, and the master unit and the plurality of units in each of the plurality of networks. A power line carrier communication for transmitting a communication signal using the distribution line as a transmission medium with a slave unit is performed, and any one of the plurality of networks is set as a main network, and among the plurality of networks At least one network other than the main network is a sub network, and the master unit of the main network has a detection unit that detects the presence or absence of a leak signal from the sub network and the leak received when the leak signal is present and a storage unit for storing the interference information in the main network signal, the interference information, der occupancy of traffic The detection unit determines the traffic occupancy rate of the received leaked signal in the main network based on the packet length of the leaked signal packet received in a predetermined period, and the modulation method and multilevel of the communication signal. It is comprised so that it may calculate .
The communication system according to the present invention includes a plurality of networks each including one master unit and a plurality of slave units connected to the same distribution line, and the master unit and the plurality of units in each of the plurality of networks. A power line carrier communication for transmitting a communication signal using the distribution line as a transmission medium with a slave unit is performed, and any one of the plurality of networks is set as a main network, and among the plurality of networks At least one network other than the main network is a sub network, and the master unit of the main network has a detection unit that detects the presence or absence of a leak signal from the sub network and the leak received when the leak signal is present A storage unit for storing interference information of the signal in the main network, wherein the interference information is a traffic occupancy rate. The detection unit calculates a traffic occupancy rate of the received leaked signal in the main network based on a transmission interval of a communication signal transmitted from the parent device of the sub network to the child device in a predetermined period. It is comprised so that it may do.
The communication system according to the present invention includes a plurality of networks each including one master unit and a plurality of slave units connected to the same distribution line, and the master unit and the plurality of units in each of the plurality of networks. A power line carrier communication for transmitting a communication signal using the distribution line as a transmission medium with a slave unit is performed, and any one of the plurality of networks is set as a main network, and among the plurality of networks At least one network other than the main network is a sub network, and the master unit of the main network has a detection unit that detects the presence or absence of a leak signal from the sub network and the leak received when the leak signal is present A storage unit for storing interference information of the signal in the main network, and the master unit of the main network If the interference information in the main network of the number is equal to or greater than a specified value, the base unit has an avoidance unit that executes avoidance processing to avoid communication interference between the main network and the sub-network, The request signal is transmitted to the plurality of slave units belonging to the same network, and a response signal is received from each of the plurality of slave units as a response to the request signal. When receiving the request signal from the sub-network, it is a process for prohibiting a certain period of time from transmitting the request signal to the plurality of slave units belonging to the main network.
The communication system according to the present invention includes a plurality of networks each including one master unit and a plurality of slave units connected to the same distribution line, and the master unit and the plurality of units in each of the plurality of networks. A power line carrier communication for transmitting a communication signal using the distribution line as a transmission medium with a slave unit is performed, and any one of the plurality of networks is set as a main network, and among the plurality of networks At least one network other than the main network is a sub network, and the master unit of the main network has a detection unit that detects the presence or absence of a leak signal from the sub network and the leak received when the leak signal is present A storage unit for storing interference information of the signal in the main network, and the master unit of the main network If the interference information in the main network of the number is equal to or greater than a specified value, the base unit has an avoidance unit that executes avoidance processing to avoid communication interference between the main network and the sub-network, The request signal is transmitted to the plurality of slave units belonging to the same network, and a response signal is received from each of the plurality of slave units as a response to the request signal. The method includes a process of reducing a transmission frequency of the request signal transmitted by the parent device of the main network.

  In the present invention, control for suppressing interference is not performed until there is no problem in communication between different networks.

1A is a schematic block diagram illustrating a communication system according to the first embodiment, and FIG. 1B is a schematic block diagram illustrating a parent device and a child device in the communication system according to the first embodiment. 2A and 2B are explanatory diagrams of signal leakage in the communication system according to the first embodiment. 6 is an explanatory diagram of occupation of leakage signal traffic in the communication system according to Embodiment 1. FIG. In the communication system which concerns on Embodiment 1, it is explanatory drawing when a request signal leaks from the main | base station of 2nd PAN to 1st PAN. 3 is a flowchart illustrating an example of an operation in the communication system according to the first embodiment. FIG. 3 is a schematic diagram illustrating a communication path in the communication system according to the first embodiment. 3 is a flowchart illustrating an example of an operation in the communication system according to the first embodiment. FIG. 8A is a schematic diagram illustrating a communication path before changing the reception sensitivity of the parent device in the communication system according to the first embodiment. FIG. 8B is a change of the reception sensitivity of the parent device in the communication system according to the first embodiment. It is the schematic which shows a later communication path | route. 3 is a flowchart illustrating an example of an operation in the communication system according to the first embodiment. 6 is an explanatory diagram illustrating an example of an operation in a communication system according to Embodiment 2. FIG. 11A and 11B are explanatory diagrams of packet interference in the communication system according to the second embodiment. FIG. 12A is an explanatory diagram when packets collide in the communication system according to the second embodiment, and FIG. 12B is an explanatory diagram when avoiding packet collisions in the communication system according to the second embodiment. 10 is a flowchart illustrating an example of an operation in the communication system according to the second embodiment. 14A and 14B are flowcharts illustrating examples of operations in the communication system according to the second embodiment.

(Embodiment 1)
As shown in FIGS. 1A and 1B, the communication system 1 according to Embodiment 1 of the present invention includes a plurality of units each including one master unit 3 and a plurality of slave units 2 connected to the same distribution line 6. Network 11-13. The communication system 1 performs power line carrier communication for transmitting a communication signal between the master unit 3 and the plurality of slave units 2 using the distribution line 6 as a transmission medium in each of the plurality of networks 11 to 13.

  Here, an arbitrary one of the plurality of networks 11 to 13 is a main network, and at least one network other than the main network among the plurality of networks 11 to 13 is a sub network.

  The master unit 3 of the main network includes a detection unit 331 and a storage unit 333. The detection unit 331 detects the presence or absence of a leakage signal from the sub network. The memory | storage part 333 memorize | stores the interference information in the main network of the leaked signal received when there exists a leaked signal.

  Moreover, the main | base station 3 of this embodiment comprises the several terminal of a main network with the several subunit | mobile_unit 2 connected to the same distribution line 6, as shown to FIG. 1A. The master unit 3 performs power line carrier communication with the plurality of slave units using the distribution line 6 as a transmission medium to transmit a communication signal.

  As shown in FIG. 1B, the parent device 3 includes a detection unit 331 and a storage unit 333. The detection unit 331 detects the presence or absence of a leakage signal from a sub network other than the main network. The memory | storage part 333 memorize | stores the interference information in the main network of the leaked signal received when there exists a leaked signal.

  Moreover, the subunit | mobile_unit 2 of this embodiment is used for the communication system 1 of this embodiment.

  By the way, in each following embodiment, the case where the same structure is employ | adopted in all the some networks 11-13 is illustrated. That is, the configuration applied to the master unit 3 of the main network is also applied to the master unit 3 of the sub network. For this reason, the master unit 3 of the secondary network has the detection unit 331 and the avoidance unit 332, like the master unit 3 of the main network.

  However, it is not essential to adopt the same configuration in all of the plurality of networks 11 to 13. For example, only the master unit 3 of the main network may have the detection unit 331 and the avoidance unit 332.

  Further, in each of the following embodiments, measurement data obtained by measuring resource consumption at each consumer is targeted at consumers of resources such as electric power, gas, water, and heat supplied from an external supplier. A meter reading system for acquisition by a server at a remote location will be described as an example of a communication system. Hereinafter, a case where the customer's facility is each dwelling unit of the apartment will be described as an example. However, the present invention is not limited to this example, and the consumer may be a detached house, an office, a factory, or the like. In the following, a case where the resource is electric power will be described as an example. However, not only electric power but also consumption of resources other than electric power can be acquired by the server. In addition, the supply amount such as the power generation amount typified by solar power generation can also be the acquisition target of the server.

  As shown in FIG. 1A, the communication system 1 of the present embodiment includes a plurality of slave units 211, 212,... 21n, 221, 222,... 22n, ... 231, 232,. Are provided for each of the networks 11 to 13. In addition, the communication system 1 of the present embodiment further includes a host device 4 that supervises a plurality of parent devices 3.

  .., 21n, 221, 222,... 22n,..., 231, 232,... 23n are referred to as “slave 2”, and when the networks 11 to 13 are not distinguished, It is referred to as “network 10”. Further, the network is also referred to as “PAN” (Personal Area Network). The PAN 10 here is a network that is set for each parent device 3 as a management range of one parent device 3, and in this embodiment, it is set for each building in an apartment house that has multiple buildings on the same site. Assuming that Of course, the PAN 10 is not limited to being set for each building on the same site, but if the set density is high, it may be set for each property in a plurality of properties (for example, multiple dwelling units) existing on different sites. Is done.

  Hereinafter, when distinguishing the master unit 3 of each PAN 10, the master unit 3 of the first PAN 11 is the first master unit 301, the master unit 3 of the second PAN 12 is the second master unit, and the master unit 3 of the third PAN 13 is the third master unit 303. And

  The subunit | mobile_unit 2 is provided in each consumer of an apartment house. Each cordless handset 2 is attached to a measuring instrument 5 that measures the consumption of resources at each consumer. The measuring instrument 5 is connected to distribution lines 61 to 63 (hereinafter referred to as “distribution line 6” when not distinguished from each other) to which electric power (resources) from an electric power supplier is supplied. It is a power meter that measures the amount of power used (resource consumption). Each of the distribution lines 61 to 63 is a low-voltage trunk line provided for each ridge of the apartment house, and the transformers 71 to 73 (hereinafter, distinguished from each other) are respectively connected to the high-voltage distribution line 60 drawn into the premises of the apartment house. When not, it is connected via “Transformer 7”). That is, the distribution line 61 is connected to the same high-voltage distribution line 60 via the transformer 71, the distribution line 62 is connected to the transformer 72, and the distribution line 63 is connected to the same high-voltage distribution line 60 via the transformer 73.

  The measuring instrument 5 constitutes a smart meter 8 together with the slave unit 2. The smart meter 8 enables remote meter reading or the like when the master unit 3 and the slave unit 2 connected to the same distribution line 6 communicate with each other. In the smart meter 8, it is preferable that the slave unit 2 and the measuring instrument 5 share a casing, but the slave unit 2 and the measuring instrument 5 may have different casings.

  The master unit 3 is provided for each ridge of the apartment house. The master unit 3 is configured to be able to communicate with a plurality of slave units 2 under the control of a plurality of slave units 2 provided in a customer (dwelling unit) in the same building. Therefore, one master unit 3 is connected to each distribution line 6, and belongs to one PAN 10 together with the slave unit 2 connected to the same distribution line 6.

  That is, the slave units 211, 212,... 21n and the first master unit 301 connected to the distribution line 61 belong to the first PAN 11, and the slave units 221, 222,. Belongs to the second PAN 12. Similarly, the slave units 231, 232,... 23 n and the third master unit 303 connected to the distribution line 63 belong to the third PAN 13.

  The communication system 1 as a meter-reading system actually includes a large number of parent devices 3, and the host device 4 can acquire measurement data from the child devices 2 under the management of each of the large number of parent devices 3. It is configured as follows. In the present embodiment, the configuration and function of the communication system 1 will be described by focusing on only one apartment house where the first PAN 11, the second PAN 12, and the third PAN 13 exist, and using the case where there are three master units 3 as a model. The purpose is not to limit the number of machines 3 to three. Of course, 1st PAN11, 2nd PAN12, and 3rd PAN13 may exist in a mutually different property (for example, apartment house), respectively. That is, this embodiment is assumed not only when a plurality of PANs 10 exist in one property, but also when one PAN 10 exists corresponding to each of a plurality of properties. In this case, the interference of communication between different PAN10 mentioned later may arise between adjacent articles.

  The host device 4 includes a server computer that collects measurement data from a plurality of consumers. The host device 4 is operated by a power company that is a supplier, or a service provider that manages power consumption and supports power saving on behalf of the power company. Here, the host device 4 has a remote meter reading function for periodically collecting measurement data of consumers under its control. That is, the host device 4 has a function of acquiring measurement data including the measurement result of the measuring device 5 from the slave device 2 managed by each parent device 3 by communicating with each parent device 3 through the dedicated line NT1. doing. As a result, the host device 4 can collect measurement data from each of the slave units 2 managed by the plurality of master units 3 via each master unit 3.

  Further, the host device 4 may be a head device that is a subordinate device of a host server operated by a supplier or the like and is provided for each region. In this case, the host device 4 is configured to collect measurement data from the parent device 3 for each region and transmit it to the host server. Thereby, the host server operated by the supplier or the like can efficiently collect the measurement data of the consumers in a plurality of regions by collecting the measurement data from the plurality of host devices 4. The host device 4 may include both such a head end device and a host server.

  Below, the concrete structure of the subunit | mobile_unit 2 and the main | base station 3 is demonstrated with reference to FIG. 1B.

  Communication between the subunit | mobile_unit 2 and the main | base station 3 is implement | achieved using the power line carrier communication (PLC: Power Line Communications) technique which transmits a communication signal using the communication path which used the distribution line 6 for the transmission medium. . That is, a communication path using the distribution line 61 as a transmission medium is formed between the slave unit 2 of the first PAN 11 and the first master unit 301, and between the slave unit 2 of the second PAN 12 and the second master unit 302. A communication path using the distribution line 62 as a transmission medium is formed. Similarly, a communication path using the distribution line 63 as a transmission medium is formed between the slave unit 2 of the third PAN 13 and the third master unit 303.

  The subunit | mobile_unit 2 transmits measurement data to the main | base station 3 of the same PAN10 by performing power line carrier communication between the main | base station 3 of the same PAN10 through such a communication channel (distribution line 6). The measurement data here includes at least the power consumption measured by the measuring instrument 5 within a predetermined period.

  Therefore, the slave unit 2 communicates with the master unit 3 (third) communication interface (hereinafter, the interface is expressed as “I / F”) 21, and the meter reading unit 22 that acquires the measurement result from the measuring instrument 5. And a (first) control unit 23 for controlling the operation of each unit. In FIG. 1B, only the handset 211 of the first PAN 11 is shown, but the other handset 2 has the same configuration.

  As described above, the communication I / F 21 is configured to perform power line carrier communication bidirectionally with the parent device 3 using the distribution line 6 on the upstream side of the measuring instrument 5 as a transmission medium.

  The meter-reading part 22 enables exchange of data between the measuring instruments 5 by the structure connected to the expansion terminal of the measuring instrument 5, for example. In addition, the meter-reading part 22 is not restricted to the structure wiredly connected with the measuring device 5, For example, the structure which performs wireless communication and optical communication with the measuring device 5 may be sufficient. Note that the measuring instrument 5 may be configured integrally with the slave unit 2.

  The control unit 23 mainly includes a device such as a microcomputer having a processor that operates according to a program, and implements various functions by executing predetermined programs. Here, the control unit 23 has a function of generating measurement data based on at least the measurement result of the measuring instrument 5 acquired by the meter-reading unit 22 and transmitting the measurement data to the parent device 3 from the communication I / F 21. Yes.

  Furthermore, the subunit | mobile_unit 2 has a memory, and is comprised so that measurement data for every fixed time (for example, 1 minute, 5 minutes, 10 minutes etc.) may be memorize | stored in a memory for a fixed period (for example, 1 day). .

  The master unit 3 is disposed in a manager room or an electrical room of the apartment house. The master unit 3 acquires measurement data from the slave units 2 of a plurality of customers (dwelling units) under its management, and transfers the acquired measurement data to the host device 4.

  Therefore, the parent device 3 controls the first communication I / F 31 that performs communication with the child device 2, the second communication I / F 32 that performs communication with the host device 4, and the operation of each unit (second) control. Part 33. In FIG. 1B, only the first base unit 301 of the first PAN 11 is shown, but the other base units 302 and 303 have the same configuration.

  As described above, the first communication I / F 31 is configured to perform power line carrier communication bidirectionally with the slave unit 2 using the distribution line 6 on the upstream side of the measuring instrument 5 as a transmission medium. . The second communication I / F 32 is connected to a dedicated line NT1 using an optical fiber or the like, and is configured to perform bidirectional communication with the host device 4 via the dedicated line NT1. In addition, the main | base station 3 is not restricted to the structure which communicates with the high-order apparatus 4 via the exclusive line NT1, but via the public network like the internet, or the high-order apparatus 4 by radio | wireless communication or power line carrier communication The structure which communicates may be sufficient.

  The control unit 33 mainly includes a device such as a microcomputer including a processor that operates according to a program, and implements various functions by executing a predetermined program. Here, the control part 33 acquires measurement data by the 1st communication I / F31 from the subunit | mobile_unit 2 of the some customer at least in a housing complex, and transmits the acquired measurement data to the high-order apparatus 4 from the 2nd communication I / F32. It has a function.

  In the communication system 1 of the present embodiment, each of the plurality of slave units 2 is configured to perform multi-hop communication in which data is transmitted using the other slave units 2 as repeaters. Therefore, the slave unit 2 that cannot directly communicate with the master unit 3 can communicate with the master unit 3 by relaying the packet by another slave unit 2 that is within a communicable distance with the master unit 3. For example, the first master unit 301 and the slave units 211, 212,... 21n with respect to the distribution line 61 are arranged from the upstream side (transformer 71 side) to the first master unit 301, the slave unit 211, the slave unit 212,. Assume that the connections are in the order of 21n. In this case, it is conceivable that the first parent device 301 communicates directly with the child devices 211 and 212 and communicates with the child device 211 as a repeater rather than directly with the child device 213.

  Therefore, when the parent device 3 communicates with the child device 2, all of the devices belonging to the same PAN 10 can be directly communicated with all the child devices 2 belonging to the same PAN 10 due to the influence of transmission distance, noise, and the like. Communication with the slave unit 2 becomes possible. Specifically, base unit 3 exchanges transmission status information for constructing a communication path (route) according to the multi-hop protocol with handset 2 belonging to the same PAN 10, and based on the information. The communication path is determined.

  Next, in the communication system 1 described above, a configuration for the parent device 3 of any PAN 10 to acquire measurement data from the managed child device 2, that is, the child device 2 of the same PAN 10 as the parent device 3. Will be described.

  The parent device 3 is configured to periodically transmit a meter reading request (request signal) to the managed child device 2 by the control unit 33. Here, when the base unit 3 reaches a predetermined time (for example, 0:00, 0:30, 10:00,...), A request signal is sent to each of the plurality of slave units 2 under management. Are sent sequentially. At this time, the base unit 3 transmits the request signal, for example, based on an identifier (meter number) unique to the smart meter 8 or at random so that the timing at which the request signal is transmitted differs for each slave unit 2. To decide.

  The subunit | mobile_unit 2 is comprised so that the meter reading response (response signal) containing measurement data may be transmitted to the main | base station 3 by the control part 23, when a request signal is received. Therefore, the parent device 3 can periodically collect measurement data from a plurality of child devices 2 under its management. The parent device 3 aggregates the measurement data collected from the plurality of child devices 2 in this way by the control unit 33 and generates meter reading information. The process in which the master unit 3 periodically acquires measurement data from the plurality of slave units 2 is hereinafter referred to as “regular meter reading”.

  Furthermore, when the master unit 3 generates the meter reading information, the control unit 33 transmits the meter reading information to the host device 4. As a result, the host device 4 can periodically acquire measurement data from a plurality of slave units 2 under the control of the master unit 3. Note that the base unit 3 may transmit the measurement data to the host device 4 by the control unit 33 every time it receives the measurement data from the handset 2.

  In this embodiment, it is assumed that the period at which the master unit 3 acquires measurement data from the slave unit 2 at the time of regular meter reading is 30 minutes. However, the period is not limited to this example. For example, 10 minutes, 15 minutes, 45 minutes, etc. Is possible. In addition, in this embodiment, it is assumed that the period for transmitting the measurement data (meter reading information) collected by the master unit 3 at the time of regular meter reading to the host device 4 is 30 minutes in the present embodiment. The date can be set as appropriate.

  By the way, the communication system 1 having the above-described configuration uses the power line carrier communication for communication between the parent device 3 and the child device 2 and uses the individual distribution lines 61 to 63 for each parent device 3. Individual PANs 11 to 13 are constructed for every three. However, the distribution lines 61 to 63 are not completely separated from each other but are connected to the same high voltage distribution line 60 via transformers 71 to 73 which are attenuation elements. For this reason, the communication signal flowing through each distribution line 6 is attenuated to some extent by the transformer 7, but may leak to other distribution lines 6 and cause communication interference between different PANs 10. If communication interference occurs between different PANs 10, collision of communication signals may occur, which may increase packet loss (packet loss). In particular, when a plurality of distribution lines 6 are laid in the same site as in the communication system 1 of the present embodiment, the plurality of distribution lines 6 are relatively close to each other, so that communication signals between different PANs 10 are transmitted. Leakage is likely to occur.

  An example of communication signal leakage will be described with reference to FIGS. 2A and 2B. In the following description, communication signals leaking from different PANs 10 are indicated by broken lines in the drawings. Here, it is assumed that the second master unit 302 of the second PAN 12 is transmitting a request signal to the slave unit 2 under its management by the control unit 33. Further, it is assumed that the slave unit 221 of the second PAN 12 transmits a response signal to the second master unit 302 by the control unit 23 in response to reception of this request signal. These request signals and response signals may leak to the first PAN 11 (here, to the first master unit 301) via the transformer 72 of the second PAN 12, the high-voltage distribution line 60, and the transformer 71 of the first PAN 11.

  Therefore, in the communication system 1 according to the present embodiment, the parent device 3 has a function for detecting that communication interference between different PANs 10 can occur.

  In the following, paying attention to any one PAN 10, among the plurality of PANs 11 to 13, any one PAN 1 to be noted is set as a main PAN (main network), and at least one PAN 1 other than the main PAN is set as a sub PAN (sub PAN). Network). That is, when paying attention to one parent device 3, the main PAN is a PAN to which the noted parent device 3 belongs among a plurality of PANs 11 to 13. For example, when focusing on the first PAN 11, the first PAN 11 becomes the main PAN, and at least one of the second PAN 12 and the third PAN 13 becomes the sub PAN. In the following description, the first PAN 11 is a main PAN and the second PAN 12 is a sub PAN unless otherwise specified.

<Detection of leak signal>
In the communication system 1 of the present embodiment, the master PAN 3 of the main PAN has the function of the detection unit 331 and the storage unit 333 in the control unit 33 as shown in FIG. 1B. The detection unit 331 detects the presence or absence of a communication signal leaked from the sub-PAN (hereinafter referred to as “leakage signal”). In addition, the storage unit 333 stores data of interference information (here, traffic occupancy) of the leaked signal received in the main PAN when there is a leaked signal. In the following description, unless otherwise specified, “traffic occupancy rate of leaked signal main PAN” is referred to as “traffic occupancy rate of leaked signal”. The storage unit 333 is a memory built in a microcomputer such as a flash memory. Of course, the storage unit 333 may not be built in the microcomputer and may be a storage device outside the microcomputer.

  Here, the interference information is a value indicating the degree of communication interference between the main PAN and the sub PAN due to the leaked signal. The interference information includes, for example, the number of master devices 3 of the main PAN and the sub PAN, the number of slave devices 2 (or the number of Hello packets), the amount of interference, and the like. Hereinafter, the traffic occupancy will be described as interference information.

  The detection unit 331 determines whether or not there is a leakage signal from the secondary PAN depending on whether or not the first communication I / F 31 has received a leakage signal from the secondary PAN base unit 3 (or the slave unit 2 under its management). Detect. Here, when detecting the presence / absence of a leakage signal from the sub-PAN, the detection unit 331 does not matter whether the received signal strength indication (RSSI) of the leakage signal is large or small. That is, the detection unit 331 detects that there is a leakage signal from the sub-PAN as long as the first communication I / F 31 receives the leakage signal.

  Further, in the communication system 1 of the present embodiment, when the detection unit 331 detects that there is a leaked signal from the secondary PAN, the detection unit 331 calculates the traffic occupancy rate of the received leaked signal. For example, the detection unit 331 may be configured to calculate the traffic occupancy rate of the received leaked signal based on the number of leaked signal packets from the secondary PAN received in a predetermined period. In this case, if the number of packets is large, the occupation ratio increases. If the number of packets is small, the occupation ratio decreases. Here, the predetermined period is assumed to be, for example, 30 minutes in accordance with the period of the regular meter reading. However, the predetermined period is not limited to this example, and can be set as appropriate, for example, 10 minutes, 15 minutes, 45 minutes. Whether or not the detection unit 331 calculates the traffic occupancy rate of the leaked signal is arbitrary.

  Also, the detection unit 331 calculates the traffic occupancy rate of the received leaked signal in the main PAN based on the packet length of the leaked signal packet received in a predetermined period, the modulation method of the communication signal, and the multivalue level. It may be configured. The multilevel value represents the number of bits transmitted in one modulation (one symbol). Here, as a modulation method, when the communication method is power line carrier communication, for example, there are an SS (Spread Spectrum) method and an OFDM (Orthogonal Frequency Division Multiplexing) method. For example, the detection unit 331 calculates the reception time of the leaked signal in the predetermined period based on the packet length of the leaked signal packet received in the predetermined period and the modulation method. And the detection part 331 calculates the occupation rate of the traffic of the received leaked signal based on this reception time. The detection unit 331 may calculate the traffic occupancy rate of the received leaked signal based on the packet length of the leaked signal packet received in the predetermined period, the modulation method, and the multilevel.

  For example, as shown in FIG. 3, the first communication I / F 31 of the first master unit 301 of the first PAN 11 receives a communication signal (response signal from the slave unit 2 of the first PAN 11) or the second PAN 12 in a predetermined period. Assume that a leaked signal is received. In this case, the detection unit 331 of the first parent device 301 calculates the traffic occupancy rate of the received leaked signal based on the reception time of the leaked signal from the second PAN 12 occupying a predetermined period. In this case, if the reception time is long, the occupation ratio increases, and if the reception time is short, the occupation ratio decreases.

  In addition, the detection unit 331 determines the traffic occupancy rate of the received leaked signal in the main PAN based on the transmission interval of the communication signal (request signal) transmitted to the slave unit 2 by the master unit 3 of the secondary PAN in a predetermined period. It may be configured to calculate. The transmission interval of the communication signal transmitted from the sub PAN base unit 3 to the sub unit 2 is a so-called polling interval. For example, as shown in FIG. 4, it is assumed that the request signal transmitted by the second master unit 302 of the second PAN 12 is leaked to the first PAN 11. Then, it is assumed that the first communication I / F 31 of the first base unit 301 of the first PAN 11 has received this request signal. Here, an interval between a request signal transmitted from the second parent device 302 to the child device 221 and a request signal transmitted from the second parent device 302 to the child device 222 is ‘T1’. The interval between the request signal transmitted from the second parent device 302 to the child device 222 and the request signal transmitted from the second parent device 302 to the child device 223 is ‘T2’. Similarly, the interval between the request signal transmitted from the second parent device 302 to the child device 22 (n−1) and the request signal transmitted from the second parent device 302 to the child device 22n is expressed as “T (n− 1) '.

  The first communication I / F 31 of the first base unit 301 receives the request signal transmitted by the second base unit 302 at intervals T1, T2,..., T (n−1) as leaked signals during a predetermined period. . And the detection part 331 of the 1st main | base station 301 is based on the average value (namely, the average value of the polling interval of the 2nd main | base station 302) of these space | intervals T1-T (n-1). Calculate the occupation rate. In this case, if the average value is small, the leakage signal traffic occupancy increases, and if the average value increases, the leakage signal traffic occupancy decreases.

  Then, the control unit 33 causes the storage unit 333 to store the traffic occupancy rate of the leakage signal calculated by the detection unit 331. Here, the control unit 33 can detect from which sub-PAN the leaked signal is leaked by referring to the network address included in the leaked signal. Therefore, the control unit 33 causes the storage unit 333 to store the traffic occupancy rate of the leaked signal for each sub PAN based on the network address included in the leaked signal.

  Here, when a unique identifier (meter number or the like) is included in the leaked signal, the control unit 33 detects not only the secondary PAN but also any terminal (master 3 or slave 2) of the secondary PAN. It is also possible to detect whether it is the generation source of In this case, the control unit 33 may store the traffic occupancy rate of the leaked signal in the storage unit 333 for each terminal of the sub-PAN based on the unique identifier included in the leaked signal.

  As described above, in the communication system 1 according to the present embodiment, the main device 3 of the main PAN includes the detection unit 331 and the storage unit 333. The detection unit 331 detects the presence or absence of a leakage signal from the sub PAN. The storage unit 333 stores the traffic occupancy rate in the main PAN of the leaked signal received when there is a leaked signal. That is, the master unit 3 of the main PAN can detect whether there is a problem in communication between different PANs 10 based on the presence / absence of a leaked signal from the sub-PAN and the occupation rate of the traffic of the received leaked signal. . For example, if the leakage signal traffic occupancy is small, it is considered that there is no problem in communication between different PANs 10, and therefore the main PAN base unit 3 may determine that processing for avoiding communication interference is unnecessary. Is possible. Therefore, in the communication system 1 of the present embodiment, control for suppressing interference is not performed until there is no problem in communication between different PANs 10 (networks).

  By the way, the leak signal from the sub PAN may be a response signal transmitted from the sub PAN slave unit 2 as well as a request signal transmitted from the sub PAN base unit 3. Therefore, the storage unit 333 distinguishes between the leakage signal from the secondary PAN base unit 3 and the leakage signal from the secondary PAN slave unit 2, and interference information (here, traffic occupancy rate) in the main PAN of the leakage signal ) May be stored. Here, as shown in Table 1 below, the storage unit 333 stores not only the traffic occupancy ratio of the leaked signal for each sub-PAN, but also the maximum value of the received strength of the leaked signal received in a predetermined period. Good. In Table 1 below, “the maximum value of the received signal strength of the leaked signal” is abbreviated as “reception strength” and “the traffic occupancy rate of the leaked signal” is abbreviated as “traffic occupancy rate”. In this configuration, the master device 3 of the main PAN can detect in more detail whether or not there is a problem in communication between different PANs 10.

＜信号の干渉の回避＞
本実施形態の通信システム１では、主ＰＡＮの親機３は、図１Ｂに示すように、検知部３３１の機能の他に、回避部３３２の機能を制御部３３に有している。なお、回避部３３２を備えるか否かは任意である。

<Avoiding signal interference>
In the communication system 1 of the present embodiment, the main PAN base unit 3 of the main PAN has the function of the avoidance unit 332 in the control unit 33 in addition to the function of the detection unit 331, as shown in FIG. 1B. Whether or not the avoiding unit 332 is provided is arbitrary.

  The avoidance unit 332 is configured to execute avoidance processing for avoiding communication interference between the main PAN and the sub PAN if the interference information (here, the traffic occupancy rate) is equal to or greater than a specified value. Yes. In other words, in the communication system 1 of the present embodiment, the master device 3 of the main PAN causes communication interference between the main PAN and the sub PAN if the interference information of the leaked signal in the main PAN is equal to or greater than a specified value. It has an avoidance unit 332 that executes avoidance processing to avoid. Of course, the interference information is not intended to be limited to the traffic occupancy rate of the leaked signal. Therefore, the interference information may be a value that takes into account the received intensity of the received leaked signal, for example, or may be another value. The specified value may be set as appropriate according to the implementation status of the communication system 1 of the present embodiment.

  In the communication system 1 according to the present embodiment, the avoidance unit 332 executes a process of reducing the reception sensitivity of the communication signal in the master unit 3 of the main PAN as the avoidance process. Specifically, the avoidance unit 332 reduces the upper limit value of the gain of an automatic gain control (AGC) circuit for reception included in the first communication I / F 31, thereby receiving the reception sensitivity of the parent device 3. Reduce. That is, the avoidance process includes a process of reducing the reception sensitivity of the master device 3 of the main PAN.

  Hereinafter, an example of the operation of the master device 3 of the main PAN in the communication system 1 of the present embodiment will be described with reference to FIG. First, the detection unit 331 detects the presence or absence of a leaked signal from the secondary PAN, and if there is a leaked signal, calculates the traffic occupancy rate of the received leaked signal (S11). Then, the avoiding unit 332 determines whether or not the calculated traffic occupancy ratio of the leaked signal is equal to or greater than a specified value (S12). If the traffic occupancy rate of the leaked signal is equal to or greater than the specified value, the avoidance unit 332 executes an avoidance process for reducing the reception sensitivity of the parent device 3 (S13). On the other hand, in the process of ‘S12’, if the traffic occupancy rate of the leaked signal is less than the specified value, the avoidance unit 332 does not execute the avoidance process (S14). The master device 3 of the main PAN executes the above operation every predetermined period. Here, as described above in <Detection of Leakage Signal>, the predetermined period is assumed to be 30 minutes in accordance with the period of the regular meter reading, but may be set as appropriate. The master device 3 of the main PAN may execute the operations of “S11” to “S14” each time a packet is received.

  As described above, in the communication system 1 according to the present embodiment, the avoidance unit 332 avoids communication interference between the primary PAN and the secondary PAN by executing an avoidance process that reduces the reception sensitivity of the parent device 3. can do. That is, if the reception sensitivity of the master PAN 3 of the main PAN decreases, even if a communication signal (leakage signal) is leaked from the sub-PAN, the leaked signal is not recognized as a communication signal, and communication interference does not occur. . That is, if the reception sensitivity is lowered to the extent that the master PAN 3 of the main PAN does not recognize the communication signal from the secondary PAN as a packet, the synchronization process cannot be started even if the leakage signal from the secondary PAN is received. Communication interference can be avoided.

<First adjustment example>
Here, a first adjustment example of how much the avoidance unit 332 reduces the reception sensitivity of the master device 3 of the main PAN in the avoidance process will be described. In the communication system 1 of the present embodiment, as already described, the plurality of slave units 2 are configured to perform multi-hop communication. For example, as shown in FIG. 6, it is assumed that the main PAN includes a parent device 3, first child devices 2A1 to 2A3, and second child devices 2B1 to 2B6. The first slave units 2A1 to 2A3 are slave units that can directly communicate with the master unit 3. The second slave units 2B1 to 2B6 are slave units that can communicate with the master unit 3 using any of the first slave units 2A1 to 2A3 as a repeater.

  In the example shown in FIG. 6, the second slave units 2B1 and 2B2 can communicate with the master unit 3 using the first slave unit 2A1 as a repeater. Second slave units 2B3 and 2B4 can communicate with master unit 3 using first slave unit 2A2 as a repeater. Second slave unit 2B5 can communicate with master unit 3 using first slave unit 2A3 as a repeater. The second slave unit 2B6 can communicate with the master unit 3 using the first slave unit 2A3 and the second slave unit 2B5 as relays. In this case, if the parent device 3 has a reception sensitivity capable of communicating with the first child devices 2A1 to 2A3, it is considered that the parent device 3 can also communicate with the second child devices 2B1 to 2B6. That is, the avoidance process lowers the reception sensitivity within a range in which communication is possible with all of the child devices (first child devices 2A1 to 2A3) belonging to the main PAN that can directly communicate with the parent device 3 of the main PAN before the avoidance process. A treatment is preferred. Note that the plurality of slave units 2 may not necessarily be configured to perform multi-hop communication.

  Hereinafter, an example of the operation of the communication system 1 of the present embodiment based on the above points will be described with reference to FIG. First, the detection unit 331 detects the presence / absence of a leaked signal from the sub-PAN, and if there is a leaked signal, calculates the traffic occupancy rate of the received leaked signal (S21). Then, the avoiding unit 332 determines whether or not the calculated traffic occupancy ratio of the leaked signal is equal to or greater than a specified value (S22). If the traffic occupancy rate of the leaked signal is equal to or greater than the specified value, the avoiding unit 332 confirms the minimum level of the reception strength of the communication signal from the first slave units 2A1 to 2A3 (S23). Then, the avoiding unit 332 estimates the reception sensitivity of the parent device 3 that can receive the communication signal having the lowest reception strength (S24).

  Next, the avoiding unit 332 determines whether or not communication interference between the main PAN and the sub PAN can be avoided based on the estimated reception sensitivity of the parent device 3 (S25). Specifically, for example, avoidance unit 332 compares the estimated reception sensitivity of base unit 3 with the reception intensity of the leaked signal from sub-PAN. When the avoidance unit 332 determines that no communication interference occurs, the avoidance unit 332 adjusts the estimated reception sensitivity as the permanent reception sensitivity of the parent device 3 (S26). On the other hand, in the process of ‘S22’, if the traffic occupancy rate of the leaked signal is less than the specified value, the avoidance unit 332 does not execute the avoidance process (S27). The master device 3 of the main PAN executes the above operation every predetermined period.

  Note that the operations of ‘S24’ to ‘S26’ may be the following operations. That is, in 'S24', the avoidance unit 332 temporarily increases the reception sensitivity of the parent device 3 to the extent that the communication signal from the first child device 2A1-2A3 can receive the communication signal having the lowest reception strength. Change it.

  Next, in ‘S25’, the detection unit 331 detects whether or not communication interference between the main PAN and the sub PAN can be avoided by temporarily changing the reception sensitivity. Specifically, the detection unit 331 detects the presence or absence of a leakage signal from the sub PAN, for example, for a certain period. Then, the detection unit 331 determines that communication interference occurs if there is a leaked signal during this fixed period, and determines that communication interference does not occur if there is no leak signal.

  If the detection unit 331 determines that communication interference does not occur in ‘S26’, the avoidance unit 332 adjusts the temporarily changed reception sensitivity as the permanent reception sensitivity of the parent device 3.

<Second adjustment example>
Even if the reception sensitivity of the main unit 3 of the main PAN is reduced as in the first adjustment example described above, if the signal level of the leaked signal is high, the leaked signal is received, and the main PAN and the sub PAN There is a risk that communication interference between the two cannot be avoided. Therefore, it is conceivable to further reduce the reception sensitivity of the main PAN base unit 3. Hereinafter, a second adjustment example of how much the avoidance unit 332 lowers the reception sensitivity of the main PAN base unit 3 in the avoidance process will be described. In the following description, it is assumed that the main PAN includes the parent device 3, the first child devices 2A1 to 2A3, and the second child devices 2B1 to 2B6, as in the first adjustment example.

  When the avoidance unit 332 lowers the reception sensitivity of the parent device 3 as compared with the first adjustment example, a child device that cannot directly communicate with the parent device 3 may appear in the first child devices 2A1 to 2A3. In the example shown in FIG. 8A, the first slave unit 2A3 cannot directly communicate with the master unit 3 by reducing the reception sensitivity of the master unit 3. In this case, the base unit 3 cannot communicate between the first handset 2A3 and the second handset 2B5 and 2B6 using the first handset 2A3 as a repeater.

  In such a case, the base unit 3 tries to reestablish the communication path by the control unit 33, thereby recovering communication with all the slave units 2 belonging to the same PAN (here, the first PAN 11). Is possible. For example, as shown in FIG. 8B, there is a case where the first slave unit 2A3 becomes a third slave unit 2C1 that can communicate with the master unit 3 using the first slave unit 2A1 as a repeater due to the reconstruction of the communication path. In this case, the second slave units 2B5 and 2B6 can communicate with the master unit 3 using the first slave unit 2A1 and the third slave unit 2C1 as relays. Therefore, the master unit 3 can communicate with all the slave units 2 by reconfiguring the communication path. In other words, the plurality of slave units 2 are configured to perform multi-hop communication in which data is transmitted using another slave unit 2 connected to the same distribution line 6 as a repeater. The avoidance process is received up to the lowest level within a range in which communication is possible with a part of the slave units (first slave units 2A1 to 2A3) belonging to the primary PAN that can directly communicate with the master unit 3 of the primary PAN before the avoidance process. A treatment for reducing the sensitivity is preferred. In this avoidance process, the slave units 2 other than the slave unit 2 that can directly communicate with the master unit 3 of the main PAN among the slave units 2 belonging to the main PAN are slave units that can directly communicate with the master unit 3 of the main PAN. It is preferable to reconstruct a communication path that can communicate with the master unit 3 of the main PAN using 2 as a repeater.

  Here, the avoidance process will be described focusing on a plurality of slave units 2 connected to one distribution line 6 among a plurality (three in this case) of distribution lines 6 shown in FIGS. 8A and 8B. However, the same avoidance process is executed for the other distribution lines 6 as well.

  Hereinafter, an example of the operation of the communication system 1 of the present embodiment based on the above points will be described with reference to FIG. First, the detection unit 331 detects the presence or absence of a leaked signal from the secondary PAN, and if there is a leaked signal, calculates the traffic occupancy rate of the received leaked signal (S31). Then, the avoiding unit 332 determines whether or not the calculated traffic occupancy ratio of the leaked signal is equal to or greater than a specified value (S32). If the traffic occupancy rate of the leaked signal is equal to or greater than the specified value, the avoiding unit 332 checks the maximum level of the received strength of the leaked signal from the sub-PAN (S33). Then, the avoiding unit 332 estimates the reception sensitivity of the parent device 3 that cannot receive the leaked signal having the largest signal level (S34).

  Next, the control unit 33 determines whether or not communication is possible with all the child devices 2 belonging to the same PAN (here, the first PAN 11) (S35). Specifically, the control unit 33 estimates whether or not communication with all the child devices 2 is possible through the current communication path. And when the subunit | mobile_unit 2 which cannot communicate on the present communication path | route exists, the control part 33 tries reconstruction of a communication path | route, and estimates whether it can communicate with all the subunit | mobile_units 2 again. When there is a slave unit 2 that cannot communicate even by reconfiguring the communication path, the avoiding unit 332 increases the estimated reception sensitivity of the master unit 3 by a certain amount (S36). After that, the control unit 33 executes the process of “S35” again.

  When it is determined in the process of 'S35' that communication can be performed with all the slave units 2, the control unit 33 determines that the estimated reception sensitivity of the master unit 3 is the same as the reception sensitivity of the master unit 3 before estimation. It is determined whether or not there is (S36). If the reception sensitivity of the parent device 3 is not the same, the avoidance unit 332 adjusts the estimated reception sensitivity as the permanent reception sensitivity of the parent device 3 (S38). On the other hand, if the reception sensitivity of the parent device 3 is the same, the process of adjusting the reception sensitivity is not executed (S39). Further, in the process of ‘S32’, if the traffic occupancy rate of the leaked signal is less than the specified value, the avoidance unit 332 does not execute the avoidance process (S39). The master device 3 of the main PAN executes the above operation every predetermined period.

  Note that the operations of ‘S34’ to ‘S38’ may be the following operations. That is, in ‘S34’, the avoidance unit 332 temporarily changes the reception sensitivity of the parent device 3 based on the maximum level of the reception strength of the leakage signal from the sub-PAN.

  Next, in ‘S35’, the control unit 33 determines whether or not communication is possible with all the slave units 2 belonging to the same PAN (here, the first PAN 11). Specifically, the control unit 33 tries whether or not communication with all the slave units 2 is possible through the current communication path. And when the subunit | mobile_unit 2 which cannot communicate on the present communication path exists, the control part 33 tries reconstruction of a communication path | route, and tries again whether it can communicate with all the subunit | mobile_units 2 again.

  Then, in ‘S36’, when there is a child device 2 that cannot communicate even by reconfiguration of the communication path, the avoiding unit 332 increases the reception sensitivity of the parent device 3 by a certain amount.

  In ‘S37’, the control unit 33 determines whether or not the changed reception sensitivity of the parent device 3 is the same as the reception sensitivity of the parent device 3 before the change. If the reception sensitivity of the parent device 3 is not the same in ‘S38’, the avoidance unit 332 adjusts the temporarily changed reception sensitivity as the permanent reception sensitivity of the parent device 3.

  By the way, in the communication system 1 of this embodiment, the avoidance unit 332 reduces the reception sensitivity of the parent device 3 in the avoidance process, but may similarly reduce the reception sensitivity of the child device 2. That is, it is preferable that the avoidance process includes a process of reducing the reception sensitivity of the handset 2 belonging to the main PAN. For example, the avoidance unit 332 executes a process of transmitting a sensitivity signal including the reception sensitivity of the parent device 3 from the first communication I / F 31 to the child device 2 belonging to the main PAN after executing the avoidance processing. And the control part 23 of the subunit | mobile_unit 2 will adjust the receiving sensitivity of the subunit | mobile_unit 2 to the receiving sensitivity contained in the said signal, if communication I / F21 receives a sensitivity signal. In this configuration, not only the parent device 3 but also the child device 2 under its management can avoid communication interference between the main PAN and the sub PAN. Note that the reception sensitivity of the slave unit 2 belonging to the main PAN does not necessarily have to be lowered to the same level as the reception sensitivity of the master unit 3 of the main PAN.

(Embodiment 2)
Hereinafter, a communication system 1 according to Embodiment 2 of the present invention will be described with reference to the drawings. In the communication system 1 of the present embodiment, the description of the components common to the communication system 1 of the first embodiment is omitted as appropriate.

  In the communication system 1 according to the present embodiment, the avoidance unit 332 of the master device 3 of the main PAN adjusts the interval at which the request signal is transmitted (that is, the polling interval) instead of the process of reducing the reception sensitivity of the master device 3. The process is executed as an avoidance process.

  Specifically, when the first communication I / F 31 receives a request signal from the secondary PAN, the avoiding unit 332 prohibits a certain period of time from transmitting the request signal to the managed slave unit 2 as an avoidance process. Execute. That is, the parent device 3 is configured to transmit a request signal to a plurality of child devices 2 belonging to the same PAN and receive a response signal from each of the plurality of child devices 2 as a response to the request signal. Yes. The avoidance process is preferably a process for prohibiting the transmission of request signals to a plurality of slave units 2 belonging to the main PAN for a certain period when a request signal is received from the sub-PAN.

  For example, as shown in FIG. 10, it is assumed that communication signals are leaked between the main PAN (first PAN 11) and the sub PAN (second PAN 12). Here, in the secondary PAN, the slave unit 2 (here, the slave unit 221) that has received the request signal from the second master unit 302 transmits a response signal to the second master unit 302. Therefore, if the request signal transmitted from the first parent device 301 of the main PAN leaks to the sub PAN, this response signal may interfere with the request signal and disappear. Also in the main PAN, the slave unit 2 (here, the slave unit 211) that has received the request signal from the first master unit 301 transmits a response signal to the first master unit 301. Therefore, if the request signal transmitted from the second master unit 302 of the secondary PAN leaks to the main PAN, this response signal may interfere with the request signal and disappear.

  Therefore, when the avoidance unit 332 of the first parent device 301 of the main PAN receives the request signal from the second parent device 302 of the sub PAN as a leakage signal, the avoidance unit 332 executes processing for prohibiting transmission of the request signal for a certain period. As a result, when a request signal transmitted from the first master unit 301 of the main PAN leaks to the sub PAN, interference between the request signal and a response signal transmitted from the slave unit 2 of the sub PAN is avoided. Can do. Similarly, when the avoidance unit 332 of the secondary PAN second master unit 302 receives the request signal from the primary PAN first master unit 301 as a leakage signal, the avoidance unit 332 executes a process of prohibiting transmission of the request signal for a certain period of time. . As a result, when a request signal transmitted from the second master unit 302 of the secondary PAN leaks to the main PAN, interference between the request signal and a response signal transmitted from the slave unit 2 of the main PAN is avoided. Can do.

  By the way, in the OSI reference model, a packet received in the physical layer is transmitted to an upper layer through a MAC (Media Access Control) layer that is a data link layer. For example, as shown in FIG. 11A, assuming that reception of a packet is started in the physical layer at time t1, reception of the packet in the upper layer can be detected at time t2 when a certain time has elapsed from time t1. is there.

  For this reason, as shown in FIG. 11B, for example, even if the reception of a packet is started in the physical layer at time t3, the upper layer cannot detect reception of the packet until time t5. Therefore, the upper layer may determine that it has not received a packet at time t4 and transmit the packet. In this case, the received packet and the transmitted packet collide (that is, interfere).

  Here, for example, as shown in FIG. 12A, it is assumed that the slave unit 211 of the main PAN (here, the first PAN 11) has received the request signal from the master unit 3 of the main PAN. Further, it is assumed that a communication signal is leaked from the sub PAN to the main PAN. In this case, even if the child device 211 receives a leaked signal from the secondary PAN in the physical layer, there is a possibility that the slave device 211 cannot transmit the packet and can transmit a response signal. Then, there is a possibility that the response signal and the leakage signal from the sub PAN interfere with each other.

  Therefore, when the slave unit 2 receives a request signal from the master unit 3 belonging to the same PAN, the slave unit 2 is configured to transmit a response signal to the master unit 3 after waiting for a certain period of time WT1. preferable. In this configuration, for example, as shown in FIG. 12B, there is a high possibility that the slave unit 211 will receive a leakage signal from the secondary PAN during a certain period WT1. Therefore, the slave unit 211 can transmit a response signal to the master unit 3 so as not to interfere with the leaked signal from the secondary PAN, so that communication interference between the main PAN and the secondary PAN is less likely to occur.

  In addition, the avoidance unit 332 of the main PAN base unit 3 may perform a process of reducing the transmission frequency of the request signal transmitted by the main PAN base unit 3 as the avoidance process. That is, the parent device 3 is configured to transmit a request signal to a plurality of child devices 2 belonging to the same PAN and receive a response signal from each of the plurality of child devices 2 as a response to the request signal. Yes. The avoidance process may include a process of reducing the transmission frequency of the request signal transmitted by the master device 3 of the main PAN. Here, the transmission frequency is the number of times that the master device 3 of the main PAN transmits a request signal in a predetermined period. Specifically, the avoiding unit 332 decreases the transmission frequency of the request signal by increasing the interval (polling interval) at which the master device 3 of the main PAN transmits the request signal. Thereby, the possibility that the request signal transmitted from the master device 3 of the main PAN and the leaked signal from the sub PAN interfere with each other can be reduced.

  Hereinafter, an example of the operation of the communication system 1 of the present embodiment based on the above points will be described with reference to FIG. First, the detection unit 331 detects the presence or absence of a leaked signal from the secondary PAN, and if there is a leaked signal, calculates the traffic occupancy rate of the received leaked signal (S41). Then, the avoiding unit 332 determines whether or not the calculated traffic occupancy ratio of the leaked signal is equal to or greater than a specified value (S42).

  If the traffic occupancy rate of the leaked signal is equal to or greater than the specified value, the avoiding unit 332 adjusts the interval (polling interval) at which the master device 3 of the main PAN transmits the request signal (S43). Specifically, the avoidance unit 332 adjusts the polling interval so as to be a value represented by the product of the polling interval before execution of the avoidance process and ‘M + 1’. Note that 'M' is a natural number representing the number of sub-PANs that are determined to cause communication interference. For example, if the number of sub-PANs determined to cause communication interference is one, the avoidance unit 332 adjusts the polling interval so that it becomes twice the polling interval before execution of the avoidance process. On the other hand, in the process of ‘S42’, if the traffic occupancy rate of the leaked signal is less than the specified value, the avoidance unit 332 does not execute the avoidance process (S44). The master device 3 of the main PAN executes the above operation every predetermined period.

  Further, the avoidance process may include a process of transmitting a notification signal to the parent device 3 of the secondary PAN. The notification signal includes a command for reducing the transmission frequency of the request signal transmitted by the parent device 3 of the secondary PAN. Hereinafter, an example of the operation of the communication system 1 according to this embodiment based on this point will be described with reference to FIGS. 14A and 14B. First, the detection unit 331 detects the presence or absence of a leaked signal from the secondary PAN, and if there is a leaked signal, calculates the traffic occupancy rate of the received leaked signal (S51). Then, the avoiding unit 332 determines whether or not the calculated traffic occupancy ratio of the leaked signal is equal to or greater than a specified value (S52).

  If the traffic occupancy rate of the leaked signal is equal to or greater than the specified value, the avoidance unit 332 causes the first communication I / F 31 to transmit a notification signal to the sub-PAN determined to cause communication interference (S53). On the other hand, in the processing of ‘S52’, if the traffic occupancy rate of the leaked signal is less than the specified value, the avoidance unit 332 does not execute the avoidance processing (S54).

  The first communication I / F 31 of the secondary PAN base unit 3 receives the notification signal (S55). Then, the avoidance unit 332 of the secondary PAN base unit 3 adjusts the interval (polling interval) at which the secondary PAN base unit 3 transmits the request signal based on the command included in the notification signal (S56). Here, the process of adjusting the polling interval is the same as the process in ‘S43’. The master device 3 of the main PAN executes the above operation every predetermined period. Note that the avoidance unit 332 of the main PAN base unit 3 may also execute a process of adjusting the polling interval of the main PAN base unit 3 in the process of ‘S53’.

  By the way, in the communication system 1 of each embodiment described above, the system may be temporarily shut down due to, for example, a power failure. In this case, the main unit 3 of the main PAN is preferably configured so that the avoidance process can be quickly executed at the time of recovery in order to avoid communication interference between the main PAN and the sub PAN. Therefore, it is preferable that the main PAN main unit 3 stores the avoidance process setting information (that is, the reception sensitivity of the main unit 3 and the transmission frequency of the request signal) in the nonvolatile memory. In this configuration, the main unit 3 of the main PAN can quickly execute the avoidance process based on the setting before the recovery by reading the setting information from the nonvolatile memory at the time of recovery by the control unit 33.

  The communication system 1 of each embodiment described above can be realized by causing a computer having a CPU (Central Processing Unit) and a memory to execute a program. The program may be stored in advance in a memory of a computer, or may be provided through a telecommunication line or recorded on a recording medium.

  This program is a program for causing a computer to function as at least the detection unit 331 and the storage unit 333. The detection unit 331 detects the presence or absence of a leakage signal from the sub PAN. The memory | storage part 333 memorize | stores the interference information in main PAN of the leaked signal received when there exists a leaked signal.

  The communication system 1 detects communication interference between different PANs 10 by the following method. That is, this method has a detection process and a storage process. The detection process is a process for detecting the presence or absence of a leakage signal from the sub-PAN. The storage process is a process in which interference information in the main PAN of a leaked signal received when there is a leak signal is stored in the storage device.

  In the communication system 1 of each embodiment of the present invention, the parent device 3 determines the transmission interval (polling interval) of communication signals, but other configurations may be used. For example, the communication system 1 of each embodiment of the present invention may be configured such that the parent device 3 has only a gateway function, and the upper server determines the polling interval.

  Moreover, in the communication system 1 of each embodiment of the present invention, the distribution lines 6 of the plurality of networks 11 to 13 are connected via the attenuation element (transformer 7), but the attenuation element may not be provided. .

  The communication system 1 according to each embodiment of the present invention has been described in detail above. However, the configuration described above is merely an example of the present invention, and the present invention is not limited to each of the above-described embodiments, and the technical idea according to the present invention is not limited to these embodiments. Various changes can be made according to the design or the like as long as they do not deviate.

DESCRIPTION OF SYMBOLS 1 Communication system 11-13 Network 2 Slave unit 3 Master unit 331 Detection part 333 Storage part 6 Distribution line

Claims (12)

A plurality of networks each having one master unit and a plurality of slave units connected to the same distribution line, and each of the plurality of networks between the master unit and the plurality of slave units; In power line carrier communication to transmit a communication signal using the distribution line as a transmission medium,
Any one of the plurality of networks is a main network, and at least one of the plurality of networks other than the main network is a sub-network,
The master unit of the main network is
A detection unit for detecting the presence or absence of a leakage signal from the sub-network;
A storage unit that stores interference information in the main network of the leaked signal received when there is the leaked signal ;
The interference information is a traffic occupancy rate,
The detection unit calculates an occupation rate of traffic in the main network of the received leaked signal based on a packet length of the packet of the leaked signal received in a predetermined period, a modulation method and a multilevel of a communication signal. It is comprised as follows . The communication system characterized by the above-mentioned .   A plurality of networks each having one master unit and a plurality of slave units connected to the same distribution line, and each of the plurality of networks between the master unit and the plurality of slave units; In power line carrier communication to transmit a communication signal using the distribution line as a transmission medium,
  Any one of the plurality of networks is a main network, and at least one of the plurality of networks other than the main network is a sub-network,
  The master unit of the main network is
  A detection unit for detecting the presence or absence of a leakage signal from the sub-network;
  A storage unit that stores interference information in the main network of the leaked signal received when there is the leaked signal;
  The interference information is a traffic occupancy rate,
  The detection unit calculates a traffic occupancy rate of the received leaked signal in the main network based on a transmission interval of communication signals transmitted from the parent device of the sub network to the child device in a predetermined period. A communication system characterized by being configured as follows.   A plurality of networks each having one master unit and a plurality of slave units connected to the same distribution line, and each of the plurality of networks between the master unit and the plurality of slave units; In power line carrier communication to transmit a communication signal using the distribution line as a transmission medium,
  Any one of the plurality of networks is a main network, and at least one of the plurality of networks other than the main network is a sub-network,
  The master unit of the main network is
  A detection unit for detecting the presence or absence of a leakage signal from the sub-network;
  A storage unit that stores interference information in the main network of the leaked signal received when there is the leaked signal;
  The master unit of the main network executes an avoidance process for avoiding communication interference between the main network and the sub network if the interference information of the leaked signal in the main network is equal to or greater than a predetermined value. Have an avoidance part to
  The master unit is configured to transmit a request signal to the plurality of slave units belonging to the same network, and to receive a response signal from each of the plurality of slave units as a response to the request signal,
  The avoidance process is a process that, when receiving the request signal from the sub-network, prohibits the transmission of the request signal to the plurality of slave units belonging to the main network for a certain period of time. system.   A plurality of networks each having one master unit and a plurality of slave units connected to the same distribution line, and each of the plurality of networks between the master unit and the plurality of slave units; In power line carrier communication to transmit a communication signal using the distribution line as a transmission medium,
  Any one of the plurality of networks is a main network, and at least one of the plurality of networks other than the main network is a sub-network,
  The master unit of the main network is
  A detection unit for detecting the presence or absence of a leakage signal from the sub-network;
  A storage unit that stores interference information in the main network of the leaked signal received when there is the leaked signal;
  The master unit of the main network executes an avoidance process for avoiding communication interference between the main network and the sub network if the interference information of the leaked signal in the main network is equal to or greater than a predetermined value. Have an avoidance part to
  The master unit is configured to transmit a request signal to the plurality of slave units belonging to the same network, and to receive a response signal from each of the plurality of slave units as a response to the request signal,
  The avoidance process includes a process of reducing a transmission frequency of the request signal transmitted by the master unit of the main network.   The storage unit distinguishes between the leaked signal from the parent device of the sub-network and the leaked signal from the child device of the sub-network, and stores interference information of the leaked signal in the main network. The communication system according to any one of claims 1 to 4, wherein the communication system is configured as follows.   The master unit of the main network executes an avoidance process for avoiding communication interference between the main network and the sub network if the interference information of the leaked signal in the main network is equal to or greater than a predetermined value. The communication system according to claim 1, further comprising an avoidance unit that performs the operation.   The communication system according to claim 3, 4, or 6, wherein the avoidance process includes a process of reducing reception sensitivity of the master unit of the main network.   The avoidance process is a process of reducing the reception sensitivity within a range in which communication is possible with all of the slave units belonging to the main network that can directly communicate with the master unit of the main network before the avoidance process is performed. The communication system according to claim 7.   The avoidance process is a process for reducing the reception sensitivity within a range in which communication can be performed with a part of the slave units belonging to the main network that can directly communicate with the master unit of the main network before the avoidance process. The communication system according to claim 7.   10. The communication system according to claim 3, wherein the avoidance process includes a process of reducing reception sensitivity of the slave unit belonging to the main network. 11.   When the slave unit receives the request signal from the master unit belonging to the same network, the slave unit is configured to transmit the response signal to the master unit after waiting for a certain period of time. The communication system according to claim 3.   The avoidance process includes a process of transmitting a notification signal including an instruction to reduce a transmission frequency of the request signal transmitted by the master unit of the sub network to the master unit of the sub network. Item 5. The communication system according to Item 4.

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