WO2015173957A1

WO2015173957A1 - Communication device and wireless mesh network

Info

Publication number: WO2015173957A1
Application number: PCT/JP2014/063093
Authority: WO
Inventors: 靖松高
Original assignee: 三菱電機株式会社
Priority date: 2014-05-16
Filing date: 2014-05-16
Publication date: 2015-11-19
Also published as: TW201545516A

Abstract

This invention includes a remote unit that is part of a wireless mesh network used by, for example, an automatic-meter-reading system. Said remote unit determines whether or not signals transmitted by a base unit that collects meter-reading data can be received directly and also determines whether or not said base unit can directly receive signals transmitted by the remote unit. If signals transmitted by the base unit can be received directly but the base unit cannot directly receive signals transmitted by the remote unit, the remote unit selects another communication device to serve as a relaying device and relay signals transmitted by the remote unit that are intended for the base unit and notifies the base unit and the relaying device that the route to be taken by signals transmitted to the base unit and the route to be taken by signals transmitted to the remote unit by the base unit are different.

Description

Communication device and wireless mesh network

The present invention relates to a wireless communication system, and more particularly, to a communication device and a wireless mesh network that perform multi-hop transfer of data or the like to its destination.

Mobile phone systems, wireless LAN systems, wireless mesh networks, and the like are known as wireless communication systems. In a wireless communication system, in order to maintain a certain communication quality, load distribution of each wireless terminal (called a base station, a mobile station, an access point, a terminal, a master station, a slave station, etc. depending on the type of system) is distributed. And operations that take into account the reduction of interference and effective use of wireless communication resources (traffic). For example, in a mobile phone system, a technique in which a radio base station adjusts a processing load by controlling transmission power according to the number of mobile stations accommodated (see Patent Document 1). In addition, a technique for adjusting the transmission power of a radio base station to an appropriate value according to the installed environment has been studied (see Patent Document 2).

Patent Document 1 describes a technique in which a radio base station adjusts the number of mobile stations accommodated by changing transmission power to adjust a processing load. According to the technique described in Patent Document 1, the radio base station increases the communication output by increasing the transmission output when the number of mobile stations accommodated is small, and reduces the communication area by decreasing the transmission output when the number of accommodates increases. Then, the mobile station at the end of the communication area is moved to another radio base station so as to adjust so as not to exceed its own processing capacity. In Patent Document 2, a large-scale area is secured with a single radio base station with high transmission power in a place with good visibility such as a mountainous area, and a radio base with low transmission power in a place with many obstacles such as buildings and poor visibility. A technique for securing a communication area using a plurality of stations is described.

JP 2013-150064 A JP 2010-154321 A

無線 Wireless mesh networks are being considered for use in automatic meter reading systems such as smart grids. That is, a system has been proposed in which communication between a concentrator (data collection device) and a smart meter (a device that measures the amount of power used and transmits the result as meter reading data to the concentrator) is established using a wireless mesh network. In such an automatic meter reading system, the concentrator collects meter reading values (meter reading data) of each smart meter at regular intervals (for example, every 30 minutes). The collected data is used to limit the amount of power used by power generation plans and demand response. In the automatic meter reading system, by accommodating as many smart meters as possible with one concentrator, the number of concentrators installed can be suppressed, and the system construction cost can be reduced. On the other hand, in a wireless mesh network, a smart meter or a repeater that does not perform meter reading is built in a multi-hop connection centered on the concentrator, so that the meter reading data of a smart meter far from the concentrator includes multiple It will reach the concentrator via a smart meter or relay. When the number of smart meters accommodated in one concentrator increases, the number of messages transmitted in the wireless mesh network increases, and it becomes difficult to collect meter reading data from all smart meters within a certain period.

The present invention has been made in view of the above, and an object of the present invention is to obtain a communication device and a wireless mesh network that can reduce wireless signals transmitted in the system.

In order to solve the above-described problems and achieve the object, the present invention is a communication device that forms a wireless mesh network applied to an automatic meter-reading system, and directly transmits a signal transmitted by a master unit that collects meter-reading data. A determination means for determining whether or not reception is possible and whether or not the parent device can directly receive a signal transmitted by itself, and a signal transmitted by the parent device can be directly received and transmitted by itself Determining means for determining a relay device that is another communication device that relays a signal addressed to the parent device transmitted by itself when the base device cannot directly receive the signal; and the master device and the relay device. On the other hand, it is characterized by comprising notifying means for notifying that a route of a signal transmitted to the parent device is different from a route of a signal transmitted from the parent device to itself.

The communication apparatus according to the present invention has an effect of reducing the number of times radio signals are transmitted.

FIG. 1 is a diagram illustrating a configuration example of a wireless mesh network according to the first embodiment. FIG. 2 is a diagram illustrating a configuration example of the slave unit. FIG. 3 is a diagram illustrating a configuration example of a repeater. FIG. 4 is a diagram illustrating a configuration example of the parent device. FIG. 5 is a diagram illustrating an example of an operation sequence in which the slave unit enters the wireless mesh network. FIG. 6 is a diagram illustrating a configuration example of a wireless mesh network according to the second embodiment. FIG. 7 is a diagram illustrating an example of an operation sequence in which a repeater enters a wireless mesh network. FIG. 8 is a diagram illustrating an example of a message format for realizing the first to third embodiments. FIG. 9 is a diagram illustrating an example of a timer value of a delivery confirmation waiting timer. FIG. 10 is a diagram illustrating the timing at which the parent device transmits entry completion to the child device. FIG. 11 is a diagram illustrating the timing at which the parent device transmits entry completion to the child device. FIG. 12 is a diagram illustrating the timing at which the child device transmits a message to the parent device. FIG. 13 is a diagram illustrating the timing at which the child device transmits a message to the parent device. FIG. 14 is a diagram illustrating the timing at which the child device transmits a message to the parent device.

Hereinafter, embodiments of a communication device and a wireless mesh network according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration example of a wireless mesh network according to a first embodiment that includes a parent device, a child device, and a relay device as communication devices according to the present invention. The wireless mesh network of the present embodiment is configured to include a parent device 1,

child devices

11, 12, 13 and 14, and a relay device 21. This wireless mesh network can be applied to, for example, an automatic meter reading system in which a meter installed in a consumer meter measures the amount of electricity, gas, water, etc. used and notifies the collecting device of the meter reading result.

Master unit 1 communicates with each slave unit and relay unit directly or via another slave unit or relay unit. Although not shown, the base unit 1 can communicate with a host device via an optical line, a mobile line, or the like. Moreover, the main | base station 1 is set as the structure which can adjust transmission output.

The slave units 11 to 14 are connected to a meter such as a smart meter and communicate with the master unit 1 directly or indirectly. That is, each slave unit communicates directly with the master unit 1 if it can transmit and receive radio waves to and from the master unit 1, and when other slave units cannot transmit and receive radio waves to and from the master unit 1, Communicate with the master unit 1 via the relay unit. The transmission output of each slave unit is fixed. In addition, the subunit | mobile_unit 11 to 14 is good also as a structure (integrated type) which incorporated instruments, such as a smart meter, and good also as an external attachment (separate type). Moreover, the subunit | mobile_units 11-14 also have a function as a relay machine mentioned later.

The relay device 21 can communicate with a peripheral child device, a parent device, or another relay device, and relays communication between the child device and the parent device that cannot perform direct communication. The transmission output of the repeater 21 is fixed.

In FIG. 1, area 2 and area 3 indicate the reach of radio signals transmitted from base unit 1 (range in which a slave unit and a relay unit can normally receive a message). Area 2 is the wireless signal reachable range when the transmission output of the master unit 1 is set higher than that of the slave unit or the relay unit, and the area 3 is set so that the transmission output of the master unit 1 is the same as that of the slave unit or the relay unit It is the reach of the radio signal when

Similarly, areas 31 to 34 indicate the reach ranges of the radio signals transmitted from the slave units 11 to 14, respectively. Area 41 indicates the reachable range of the radio signal transmitted by the repeater 21.

When the transmission output of the master unit 1 is set higher than that of the slave unit or the relay unit, the reach range of the radio signal is the area 2, and the slave unit 13 exists in this area 2. Therefore, the slave unit 13 transmits from the master unit 1. The received message 53 can be received directly. On the other hand, when the transmission output of the master unit 1 is set to the same setting as that of the slave unit or the relay unit, the reach range of the radio signal is the area 3, and the slave unit 13 does not exist in this area 3. It becomes impossible to directly receive the message 53 transmitted from. In this case, the slave unit 13 receives a message from the master unit 1 via the slave unit 12, for example.

In addition, since the parent device 1 does not exist in the area 33, when the child device 13 transmits the message 51 addressed to the parent device 1, the child device 12 existing in the area 33 receives the message 51 and receives it as the message 52. Transfer to machine 1.

FIG. 2 is a diagram illustrating a configuration example of the slave units 11 to 14. The configurations of the slave units 11 to 14 are the same, and include a PHY 101, a MAC 102, a CPU 103, a ROM 105, a RAM 106, a nonvolatile memory 107, and an instrument IF 108. The CPU 103 includes a communication processing unit 104.

In the slave units 11 to 14, the PHY 101 is an interface for communicating with other slave units, relay units, and the master unit, and transmits and receives radio signals via the antenna 100. The MAC 102 has a function of controlling the PHY 101 and manages MAC addresses. The CPU 103 performs various processes as a slave unit. A communication processing unit 104 provided in the CPU 103 performs selection of a route to the parent device 1, transmission / reception of a message, transfer processing of a message, and the like. Although not shown, the CPU 103 performs processing according to the content of the received message and communication processing with a meter such as a smart meter. The communication processing unit 104 may perform communication processing with the instrument. The ROM 105 stores an operation program as a slave unit. The RAM 106 is used for storing temporary information. The nonvolatile memory 107 stores path information, data collected from a meter such as a smart meter, and the like. The meter IF 108 is a communication interface for acquiring meter reading data from a meter such as a smart meter, making various settings for the meter, controlling the meter, and the like.

FIG. 3 is a diagram illustrating a configuration example of the repeater 21. As shown in the figure, the repeater 21 has a configuration in which the instrument IF 108 is deleted from the slave units 11 to 14 shown in FIG. That is, the relay device 21 has the same function as the slave device except that it does not communicate with a meter such as a smart meter.

FIG. 4 is a diagram illustrating a configuration example of the base unit 1. As shown in the figure, the master unit 1 has a configuration in which the instrument IF 108 provided in the slave units 11 to 14 shown in FIG. The host device IF 109 is an interface for communicating with the host device via an optical line, a mobile phone line, or the like. The communication processing unit 104 of the parent device 1 manages communication paths with all the child devices and relay devices that have entered the parent device (parent device 1). The operations of the other constituent elements are the same as those of the slave units 11 to 14.

Next, characteristic operations of the base unit 1, the slave units 11 to 14 and the relay unit 21 constituting the wireless mesh network, specifically, operations of the slave unit and the relay unit entering the wireless mesh network will be described. To do. Since the entry operations of the slave units 11 to 14 and the entry operation of the relay unit 21 are the same, here, as an example, the operation when the slave unit 13 illustrated in FIG. 1 enters the wireless mesh network will be described. In addition, although the subunit | mobile_unit 12 and the relay machine 21 exist in the reach | attainment range (area 33) of the radio signal which the subunit | mobile_unit 13 transmits, the subunit | mobile_unit 12 is a wireless mesh network (wireless managed by the main | base station 1). It is assumed that the relay network 21 has not entered the wireless mesh network. Further, it is assumed that the transmission output of the parent device 1 is set higher than that of the child devices 11 to 14 and the relay device 21, and the reachable range of the radio signal transmitted by the parent device 1 is area 2.

FIG. 5 is a diagram illustrating an example of an operation sequence in which the slave unit 13 enters the wireless mesh network. In the following description, an area indicating a radio signal reachable range is referred to as a signal reachable area. For example, area 2 indicating the reach of the radio signal transmitted by base unit 1 is referred to as “signal reach area 2 of base unit 1”.

When the child device 13 is activated and does not enter the wireless mesh network, the child device 13 first transmits a peripheral search request by broadcast in order to search for a wireless mesh network that can be entered (step S11). In this case, a unique message name is used, but standards such as “Enhanced Beacon Request” and “Enhanced Beacon” defined in IEEE802.15.4e may be followed. The messages used in the present embodiment are not limited to these. Any message can be used as long as it is a similar message. The same applies to subsequent messages.

Since the master unit 1 is located outside the signal arrival area 33 of the slave unit 13, it cannot receive the peripheral search request. The subunit | mobile_unit 12 and the relay machine 21 receive a periphery search request | requirement. Since the repeater 21 itself has not yet entered, it ignores the surrounding search request and discards the received surrounding search request (step S12). On the other hand, since the handset 12 has already entered the wireless mesh network, it transmits a peripheral search response to the handset 13 and has entered the wireless mesh network, and the accommodation destination is the base unit 1. The communication path up to this point (in this example, direct communication with the base unit 1 is possible) is notified to the handset 13 (step S13). In addition to the communication path, the communication quality (such as RSSI (Received Signal Strength Indicator) value) and the communication quality (error rate) with the next-hop wireless terminal (master unit, slave unit, relay unit) , Transmission delay, etc.) may be notified.

When receiving the peripheral search response, the slave unit 13 recognizes that it can communicate with the master unit 1 via the slave unit 12, and selects the slave unit 12 as a route to the master unit 1 (step S14). Then, an entry request is transmitted by unicast to the parent device 1 via the child device 12 (step S15). In the present embodiment, since the handset 13 receives the peripheral search response only from the handset 12, the handset 12 is selected as the transmission destination of the message addressed to the base unit 1. However, when there are a plurality of child devices or relay devices that have already entered, a transmission destination of a message addressed to the parent device 1 is selected from among them. That is, the slave unit 13 waits for a peripheral search response for a certain period after transmitting the peripheral search request, and receives a peripheral search response from a plurality of wireless terminals (slave unit, relay unit, base unit). The wireless terminal that becomes the optimum route is selected from the wireless terminals that have transmitted the surrounding search response, and an entry request is transmitted. The subunit | mobile_unit 13 selects a path | route (wireless terminal used as the transmission destination of an entry request) in consideration of the hop number etc. to the main | base station 1.

When receiving the entry request from the slave unit 13, the slave unit 12 confirms delivery (returns ACK) and transfers the entry request to the master unit 1 (steps S16 and S18). When receiving the ACK for the entry request, the slave unit 13 starts monitoring whether or not a response to the entry request can be received directly from the master unit 1 (step S17). This monitoring continues until a response is received or until a certain time has elapsed. Here, monitoring is started after waiting for reception of ACK, but may be started immediately after the entry request is transmitted in step S15. Also, monitoring may not be started when the number of hops to base unit 1 is greater than a certain value (for example, the number of hops according to the transmission power setting of base unit 1 such as 3 hops).

When the base unit 1 receives the entry request, it returns an ACK (step S19). Then, a response and authentication request is transmitted in order to determine whether the entry request has been received and whether or not entry of the slave unit 13 (entry request transmission source) requesting entry is permitted. At this time, the information on the route through which the entry request has been transmitted is added to the response / authentication request and transmitted to the child device 12 by unicast (step S20). As shown in FIG. 1, since the

slave units

11, 12, and 13 exist in the signal arrival area 2 of the master unit 1, the response / authentication request transmitted in step S <b> 20 is sent to each slave unit in the signal arrival area 2. Received by. Although not shown in FIG. 5, since the slave unit 11 does not transmit or transfer an entry request, it is ignored even if a response / authentication request is received (transfer of the received response / authentication request). And the response and authentication request is discarded without confirming delivery).

When receiving the response / authentication request as a response to the entry request transmitted in step S15 directly from the parent device 1, the child device 13 recognizes that direct reception from the parent device 1 is possible (step S22). Then, it does not transmit an ACK for the response / authentication request, but waits for the same response / authentication request received directly from the parent device 1 to be transferred from the child device 12 to itself.

When receiving the response / authentication request as a response to the entry request transferred in step S18 from the parent device 1 (step S20), the slave unit 12 returns an ACK (step S21), and the response / authentication request is the destination. It transfers to the subunit | mobile_unit 13 (step S23).

When the slave unit 13 receives the response and authentication request transferred by the slave unit 12, the slave unit 13 returns an ACK (step S24), and then performs an authentication process. In FIG. 5, the description of the authentication process is omitted. When the authentication process is completed, the slave unit 13 transmits an authentication response including the authentication result to the master unit 1 by unicast (step S25). In step S25, information indicating that the message can be directly received from the parent device 1 is added to the authentication response and transmitted.

When receiving the authentication response, the slave unit 12 returns an ACK to the slave unit 13 (step S26), and transfers the authentication response to the master unit 1 (step S27). At this time, the slave unit 12 confirms the information added to the authentication response and recognizes that the slave unit 13 can directly receive the message transmitted from the master unit 1. That is, when a unicast message addressed to the parent device 1 is received from the child device 13, it is unnecessary to return an ACK, and even if the unicast message addressed to the child device 13 is not transmitted, the child device 13 In some cases, an ACK addressed to itself is received, and in this case, it is stored that the ACK is unconditionally transferred to the base unit 1.

When receiving the authentication response from the child device 12, the parent device 1 returns an ACK to the child device 12 (step S28). And it is judged from the authentication result contained in an authentication response whether the subunit | mobile_unit 13 enters into an own wireless mesh network. When entering, it recognizes that direct transmission to the subunit | mobile_unit 13 is possible from the information (information which shows that the subunit | mobile_unit 13 can receive a message directly) added to the authentication response (step S29). ). Then, the entry completion is transmitted directly to the child device 13 instead of via the child device 12 (step S30).

When the slave unit 13 directly receives the completion of entry from the master unit 1, the upstream communication path (communication path from itself to the master unit 1) and the downstream communication path (communication path from the master unit 1 to itself) are asymmetric. It is determined that the child device 12 and the parent device 1 have grasped the situation, and an ACK for entry completion is transmitted to the child device 12 instead of the parent device 1 that is the entry completion transmission source (step S31).

The slave unit 12 recognizes that the entry of the slave unit 13 is permitted by monitoring the completion of entry transmitted from the master unit 1 to the slave unit 13 or by receiving an ACK for the completion of entry from the slave unit 13. To do. And the subunit | mobile_unit 12 starts the operation | movement which does not return ACK, when the unicast message addressed to the main | base station 1 is received from the subunit | mobile_unit 13, and the unicast which self does not transmit to the subunit | mobile_unit 13 When an ACK for the message is received from the slave unit 13, an operation for unconditionally transferring the message to the master unit 1 is started. When receiving the ACK transmitted from the slave unit 13 in step S31, the slave unit 12 transfers the ACK to the master unit 1 (step S32). In addition, the subunit | mobile_unit 12 cannot monitor the completion of entry with respect to the subunit | mobile_unit 13 for a fixed period, or when the ACK with respect to entry completion cannot be received from the subunit | mobile_unit 13, if the entry process of the subunit | mobile_unit 13 is not completed normally It judges and returns to normal operation (operation before receiving a periphery search request from the subunit | mobile_unit 13).

When the entry process with respect to the master unit 1 is normally completed, the slave unit 13 notifies the master unit 1 of data (meter reading values, etc.) periodically collected from a smart meter or the like by a periodic meter reading notification (step S33). The slave unit 13 transmits a periodic meter reading notification to the master unit 1 via the slave unit 12. Since the handset 12 can directly receive the message from the base unit 1, the handset 12 forwards a periodic meter reading notification to the base unit 1 without transmitting an ACK to the handset 13. (Step S34). When the master unit 1 receives the periodic meter reading notification from the slave unit 13 via the slave unit 12, the master unit 1 knows that the slave unit 13 can directly receive a message from itself. An ACK is directly transmitted to the address (step S35).

When this embodiment is applied, as shown in FIG. 5, in the message transmission from the parent device 1 to the child device 13 as compared with the conventional case (a wireless mesh network having the same uplink and downlink routes), The number of message transmissions can be reduced by one. That is, since transmission from the child device 12 to the child device 13 is not required, message transmission by the child device 12 can be reduced (see steps S30 to S32). Further, in the message transmission from the child device 13 to the parent device 1, ACK transmission can be reduced once. That is, since it is not necessary to return the ACK by the child device 12 that has received the message from the child device 13, the transmission of the ACK by the child device 12 can be reduced (see steps S33 to S35).

In the present embodiment, a case has been described in which a single slave unit is relayed. However, a plurality of slave units are provided on the route (upstream route) from the slave unit 13 to the master unit 1 that can directly receive a message transmitted by the master unit 1. When there is a device / relay device, the number of message transmissions in communication from the parent device 1 to the child device 13 and the number of ACK transmissions in communication from the child device 13 to the parent device 1 can be reduced by the number of the devices / relay devices. . In such a wireless mesh network, when data from each child device is aggregated in the parent device, there are a plurality of child devices using the child device 13 as a relay path (in FIG. 1, after the child device 13 enters, The relay device 21 and the slave device 14 enter the master device 1 using the slave device 13 as a relay path), and the same effect can be obtained with respect to the slave device / relay device. Therefore, the number of message transmissions can be further reduced as a whole system. As a result, in a system that collects meter reading values within a certain period, the number of slave units that can be accommodated by one master unit can be increased, and the number of master units to be installed can be reduced. System costs can be reduced by reducing the number of master units.

As described above, in the wireless mesh network according to the present embodiment, the master unit transmits a radio signal with a higher transmission output than the slave units and repeaters accommodated therein. When a wireless terminal (slave unit, repeater unit) located at the end of the reach of the radio signal transmitted by the base unit (a location away from the base unit) communicates with the base unit, it transmits a downstream message to the base unit. Directly received from the machine and sends an upstream message via the relay terminal (slave machine or relay machine). When the relay charge terminal receives a message addressed to the base unit from the wireless terminal, the relay terminal omits delivery confirmation (return of ACK) to the base station and transfers the message to the base unit. In addition, when the relay charge terminal receives a delivery confirmation addressed to the parent device from the wireless terminal, the relay terminal transfers it to the parent device. As a result, the above-described effects (reduction in the number of message transmissions, increase in the number of slave units and repeaters that can be accommodated by the master unit, and cost reduction of the system) can be obtained.

Embodiment 2. FIG.
FIG. 6 is a diagram illustrating a configuration example of a wireless mesh network according to the second embodiment. The wireless mesh network of the present embodiment is obtained by adding a handset 15 to the wireless mesh network (see FIG. 1) of the first embodiment. The configuration of the slave unit 15 is the same as that of the slave units 11 to 14 (see FIG. 2). In the wireless mesh network of the present embodiment, the transmission output of the relay device 21 is set higher than the slave devices 11 to 15 as compared with the wireless mesh network of the first embodiment. The reach range of the radio signal transmitted by the repeater 21 of the present embodiment is defined as an area (signal reach area) 42. Further, it is assumed that the slave unit 13 cannot directly receive the radio signal transmitted by the master unit 1. The configuration of each wireless terminal (master unit, slave unit, and relay unit) forming the wireless mesh network is the same as that of the first embodiment (see FIGS. 2 to 4).

Next, the operation of the repeater 21 entering the wireless mesh network having the configuration shown in FIG. 6 will be described. The slave units 12 to 15 exist in the signal arrival area 42 of the repeater 21, but the

slave units

12 and 13 have already entered the wireless mesh network, and the

slave units

14 and 15 have not entered the wireless mesh network.

FIG. 7 is a diagram illustrating an example of an operation sequence in which the repeater 21 enters the wireless mesh network.

When the relay machine 21 is activated and does not enter the wireless mesh network, the relay machine 21 first transmits a peripheral search request to search for an available wireless mesh network (step S41).

Since the base unit 1 is located outside the signal arrival area 42, it cannot receive the peripheral search request transmitted by the relay unit 21. The slave units 12 to 15 located in the signal arrival area 42 receive the neighborhood search request, and the

slave units

12 and 13 that have already entered the wireless mesh network transmit a neighborhood search response to the relay device 21. The subunit | mobile_unit 12 memorize | stores that when the periphery search request | requirement is received (step S44). Although not shown in the figure, the slave unit 13 similarly stores a message to that effect when it receives a peripheral search request.

Since the repeater 21 is located outside the signal arrival area 32 of the slave unit 12 (see FIG. 6), the periphery search response transmitted by the slave unit 12 does not reach the repeater 21, and the periphery transmitted by the slave unit 13 Only the search response reaches the repeater 21 (steps S42 and S43). In addition, although illustration is abbreviate | omitted, even if the subunit | mobile_unit 14 and 15 which has not entered into a wireless mesh network receives a periphery search request | requirement, it will be disregarded. The surrounding search response is the same as the surrounding search response described in the first embodiment.

The relay device 21 receives the surrounding search response for a certain period and, as a result, receives the surrounding search response only from the slave unit 13, so that the destination is set to the parent device 1 according to the communication path notified by the received surrounding search response. And the entry request that sets the route from the slave unit 13 and the slave unit 12 to the master unit 1 (slave unit 13 → slave unit 12 → route of the master unit 1) as route information is addressed to the slave unit 13 Unicast transmission is performed (step S45).

The entry request transmitted by the relay device 21 is received by the

slave devices

12 and 13. When receiving the entry request, the slave unit 13 returns an ACK to the relay unit 21 and transfers the entry request to the slave unit 12 (steps S46 and S47). The subunit | mobile_unit 12 receives the entry request transmitted by the relay device 21, and the entry request transferred by the subunit | mobile_unit 13. FIG. When the slave unit 12 receives the entry request transmitted from the repeater 21, the slave unit 12 confirms the route information set in this, and the route indicated by the route information is different from the actual reception route of the join request, so that the slave unit 12 has transmitted it. It is recognized that the message does not reach the repeater 21 (direct reception from the repeater 21 is possible but direct transmission to the repeater 21 is not possible) (step S49). On the other hand, when the entry request transferred by the slave unit 13 is received, an ACK is returned because the route indicated by the set route information matches the actual reception route (step S48). Then, the entry request is transferred to the parent device 1 (step S50).

When the base unit 1 receives the entry request, it returns an ACK (step S51). Then, a response and authentication request is transmitted in order to determine whether the entry request has been received and whether or not entry of the repeater 21 (entry request transmission source) requesting entry is permitted. At this time, the information of the route through which the entry request has been transmitted is added to the response / authentication request, the final destination is set in the relay device 21, and the unicast is transmitted to the child device 12 (step S52).

When receiving the response / authentication request addressed to the relay device 21, the child device 12 returns an ACK to the parent device 1 (step S 53), and further proceeds to the child device 13 according to the path information set in the response / authentication request. Transfer (step S54). In step S54, information indicating that the message can be directly received from the repeater 21 is added to the response / authentication request and transmitted.

When the slave unit 13 receives the response / authentication request, the slave unit 13 returns an ACK to the slave unit 12 (step S55), and further transfers the response / authentication request to the relay device 21 that is the final destination (step S56). At this time, the slave unit 13 confirms the information added to the response / authentication request, and grasps that the slave unit 12 can directly receive the message transmitted from the relay unit 21. That is, message transmission from the relay device 21 to the child device 12 is performed directly without going through itself, and an ACK (ACK addressed to the relay device 21) of the message directly transmitted from the relay device 21 to the child device 12 is received as a child. If it is received from the mobile device 12, it must be transferred to the relay device 21. If a message addressed to the relay device 21 is received from the slave device 12, it is not necessary to transmit ACK (transmit ACK to the slave device 12. Transfer the message to the repeater 21 without doing so).

When the relay device 21 receives the response / authentication request, the relay device 21 returns an ACK to the child device 13 (step S57). And while performing an authentication process, the information added to the response and authentication request | requirement is confirmed, and it recognizes that the subunit | mobile_unit 12 can directly receive the message which self transmitted (step S58). In FIG. 7, the description of the authentication process is omitted. When the authentication process is completed, the relay device 21 transmits an authentication response including the authentication result to the parent device 1 by unicast (step S59). In this step S59, an authentication response in which the parent device 1 is set as the final destination is transmitted to the child device 12.

When receiving the authentication response from the relay device 21, the slave device 12 transmits an ACK with the relay device 21 as the final destination to the relay device 21 via the slave device 13 (steps S60 and S61), and the authentication response is transmitted to the master device 1. (Step S62).

When receiving the authentication response from the child device 12, the parent device 1 returns an ACK to the child device 12 (step S63). Then, from the authentication result included in the authentication response, it is determined whether or not the repeater 21 is allowed to enter its own wireless mesh network. When entering, the completion of entry is transmitted through a route passing through the slave units 12 and 13 (step S64). That is, the entry completion in which route information indicating the route passing through the

slave units

12 and 13 is set is transmitted.

When receiving the entry completion, the child device 12 returns an ACK to the parent device 1 (step S65), and transfers the entry completion to the child device 13 (step S66).

When receiving the entry completion from the child device 12, the child device 13 forwards the entry completion to the relay device 21 without transmitting an ACK because the destination is the relay device 21 (step S67).

When the relay device 21 receives the entry completion, it transmits an ACK to the child device 12 (step S68).

Thus, in the wireless mesh network of the present embodiment, the relay station transmits a radio signal with a higher transmission output than the slave unit. When the slave unit located at the end of the reach of the wireless signal transmitted by the repeater (a place away from the repeater) communicates with the repeater, it directly receives the message sent from the repeater to itself. However, when a message is transmitted to the repeater, it is transmitted via another slave unit. When the other slave unit in charge of relay receives a message addressed to the relay unit, the delivery confirmation (return of ACK) is omitted and the message is transferred to the relay unit. In addition, when the other child device in charge of relay receives the delivery confirmation addressed to the relay device, it transfers it to the relay device. Thereby, the effect similar to Embodiment 1 can be acquired. That is, the number of messages and ACKs transmitted between the slave unit and the relay unit between the master unit and the relay unit can be reduced as in the first embodiment.

Embodiment 3 FIG.
In the second embodiment, the operation when the repeater 21 illustrated in FIG. 6 enters the wireless mesh network has been described. However, in the present embodiment, the slave unit 15 illustrated in FIG. 6 enters the wireless mesh network. The operation in this case will be described. Assume that the slave units 12 to 14 and the relay unit 21 shown in FIG. 6 have already entered the wireless mesh network.

As shown in FIG. 6, since the handset 15 is in the signal arrival area 42, the handset 15 can directly receive the radio signal (message or ACK) transmitted by the repeater 21. On the other hand, since the repeater 21 is outside the signal arrival area 35, it cannot directly receive the radio signal transmitted by the slave unit 15 and receives a message or ACK from the slave unit 15 via the slave unit 14. It will be. This state is the same as the relationship between the child device 13 and the parent device 1 described in the first embodiment (see FIG. 1). Therefore, the operation of the relay device 21 when the child device 15 enters the wireless mesh network is similar to the operation (see FIG. 5) of the parent device 1 described in the first embodiment. That is, the authentication process is excluded from the operation of the base unit 1. The repeater 21 operates as the master unit 1 shown in FIG. 5, the slave unit 14 operates as the slave unit 12 shown in FIG. 5, and the slave unit 15 operates as the slave unit 13 shown in FIG. The effect of can be obtained.

Here, the format of a message used for realizing the first to third embodiments will be described. FIG. 8 is a diagram illustrating an example of a message format for realizing the first to third embodiments. As shown in the figure, the message is composed of a header part and a data part, and the main part of the message (entry request, response / authentication request, etc.) is stored in the data part. In the header part, as information necessary for delivering the message from the transmission source to the transmission destination, the next transmission destination address, own address, message transmission destination address, message transmission source address, route information (from the transmission source to the transmission destination of the message) Route), sequence number (sequence No.), and extension area. In the extended area, device type # 1, direct receivable source address, device type # 2, and direct receivable destination address are stored.

The message format will be described with reference to the sequence shown in FIG. Here, a case where the child device 12 transfers an entry request from the child device 13 to the parent device 1 (corresponding to step S18) will be described as an example. The address of the parent device 1 is stored in the next transmission destination address of the entry request transferred from the child device 12 to the parent device 1, and the address of the child device 12 is stored in the own address. The message transmission destination address stores the address of the parent device 1 that is the final destination of the entry request, and the message transmission source address stores the address of the child device 13 that is the transmission source of the entry request. As the address, a device-specific MAC address or IP address is used. The sequence number is used for confirmation of delivery between wireless terminals, retransmission, message loop detection on a wireless path, and the like, and is a number assigned to each message by a transmitting wireless terminal.

The extended area is information set as necessary. For example, it is set in the authentication response transmitted in step S25 of FIG. 5 and each subsequent message and ACK. In each message and ACK after step S25 in FIG. 5, information indicating “master” is set for model type # 1, and the address of master 1 is set for the directly receivable source address. Information indicating “slave unit” is set for the model type # 2, and the address of the slave unit 13 is set for the directly receivable transmission destination address. Thereby, the subunit | mobile_unit 13, the subunit | mobile_unit 12, and the main | base station 1 can recognize that the subunit | mobile_unit 13 can receive the transmission from the main | base station 1 directly. The slave unit 12 is located between the master unit 1 and the slave unit 13 based on the route information from the transmission source to the destination of the message and the extended area information, and is transmitted from the master unit 1 to the slave unit 13. In the case of, the message and ACK are transmitted without going through the device itself, and in the case of transmission from the child device 13 to the parent device 1, it can be recognized that the message is sent through itself. That is, if the slave unit 12 receives a message from the slave unit 13, the slave unit 12 transfers the message to the master unit 1 without transmitting an ACK to the slave unit 13. If receiving the ACK from the slave unit 13, the slave unit 12 It is possible to implement control for transferring ACK to. When the handset 12 performs such control, the number of message and ACK transmissions can be reduced.

Embodiment 4 FIG.
A wireless mesh network according to the fourth embodiment will be described. The configuration of the wireless mesh network and the configurations of the parent device, the child device, and the relay device are the same as those in the first embodiment (see FIGS. 1 to 4). The message and ACK transmission / reception sequence is the same as in the first or second embodiment (see FIGS. 5 and 7).

In the sequence shown in FIG. 5, the time from when the master unit 1 transmits a response / authentication request to the slave unit 12 at step S20 until it receives an ACK at step S21, and the master unit 1 completes entry at step S30. Since the transmission of ACK occurs after the transmission to the child device 13 until the ACK is received in step S32, the latter is longer. Therefore, if the reception wait time of ACK is set to be the same for the former (when the slave unit 12 transmits ACK) and the latter (when the slave unit 13 transmits ACK), retransmission due to ACK not being received (participation completion) There is a risk that the frequency of occurrence of retransmission will increase. In the sequence example shown in FIG. 5, the number of relays is 1. However, the number of relays may be 2 or more. If the number of relays is increased, retransmission is more likely to occur.

In the sequence shown in FIG. 7, the same applies when the relay device 21 transmits an authentication response to the child device 12 in step S59 and then receives ACK in step S61.

Further, in the sequence shown in FIG. 5, when the handset 13 transmits a periodic meter reading notice in step S33 and receives ACK in step S35, or in the sequence shown in FIG. 7, the handset 12 in step S66. The same applies when ACK is received in step S68 after the entry completion is transmitted.

Therefore, in the wireless mesh network of the present embodiment, the time that each wireless terminal (base unit, slave unit, relay unit) waits for reception of ACK (ACK reception waiting timer) is set to a value corresponding to the number of relays. For example, assume a value according to FIG. FIG. 9 shows a timer value of an acknowledgment wait timer that is activated by the message sender when the ratio of the number of relays between the message and its acknowledgment (ACK) is 1: N or N: 1 (acknowledgment waiting time of ACK). It is a figure which shows an example. The master unit, the relay unit, and the slave unit hold the table shown in FIG. 9 in the ROM or nonvolatile memory, and use a timer value corresponding to the ratio of the number of relays. In the case of following FIG. 9, the master unit, the relay unit, and the slave unit have a timer value T when no message or ACK relay occurs (when direct communication is possible in both directions), and as the number of relays increases, The timer value is increased to T × 2, T × 3,. Thereby, it is possible to suppress the occurrence of retransmission due to ACK not being received. In addition, it is not necessary to wait for delivery confirmation more than necessary, and communication efficiency can be increased.

Note that “asymmetric route relaying number ratio = 1” means that the upstream and downstream routes are not asymmetrical and bi-directional direct communication is possible (normal case). For example, the relationship between the slave unit 12 and the slave unit 13 shown in FIG. In FIG. 9, the normal timer value T of 1: 1 is multiplied by the number of relays. However, this is an example, and there is a margin in the original timer value T. If the number of relays is small, If the same value T is used as it is and the number of relays exceeds a certain threshold value, for example, every 3 multiples, 2 times or 3 times may be used.

Embodiment 5 FIG.
A wireless mesh network according to the fifth embodiment will be described. The configuration of the wireless mesh network and the configurations of the parent device, the child device, and the relay device are the same as those in the first embodiment (see FIGS. 1 to 4). The message and ACK transmission / reception sequence is the same as in the first embodiment (see FIG. 5). The message and ACK transmission / reception sequence is the same as in the first or second embodiment (see FIGS. 5 and 7).

In the wireless mesh network of the present embodiment, the parent device, the child device, and the relay device transmit messages by CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance) control.

When CSMA / CA control is applied, the wireless terminal (base unit, slave unit, repeater) must monitor the transmission status of radio waves from other wireless terminals and detect radio waves during LIFS (long interframe spacing). For example, the message is transmitted when the back-off (random delay) further elapses. In addition, in order to ensure the delivery confirmation of the received message with certainty, if the wireless terminal that receives the message does not detect the radio wave for a short interframe spacing (SIFS) shorter than the LIFS, at that time, the ACK Send. Thereby, since transmission of ACK is prioritized over transmission of message, it is possible to prevent the retransmission of the message due to the fact that the ACK cannot be transmitted (the message transmitting side cannot receive the ACK).

FIG. 10 and FIG. 11 are diagrams for explaining transmission timing when the parent device 1 transmits entry completion to the child device 13 in the sequence shown in FIG. FIG. 10 shows the transmission timing when CSMA / CA control is applied to a conventional wireless mesh network, and FIG. 11 shows the transmission timing in the wireless mesh network of the present embodiment.

If the configuration of the conventional wireless mesh network is the one shown in FIG. 1, when CSMA / CA control is applied, as shown in FIG. 10, the master unit 1 sets the final destination as a child after LIFS + backoff. The entry completion as the machine 13 is transmitted to the child machine 12. When receiving the completion of entry in which the final transmission destination is the child device 13 from the parent device 1, the child device 12 transmits an ACK to the parent device 1 after SIFS. Thereafter, the slave unit 12 transmits entry completion to the slave unit 13 that is the final transmission destination after LIFS + backoff. When receiving the entry completion addressed to itself, slave unit 13 transmits ACK to slave unit 12 after SIFS.

On the other hand, in the wireless mesh network according to the present embodiment, as shown in FIG. 11, base unit 1 directly transmits entry completion to handset 13 after LIFS + backoff. When receiving the entry completion from the parent device 1, the child device 13 transmits an ACK with the final transmission destination as the parent device 1 to the child device 12 after SIFS. When receiving the ACK whose final transmission destination is the parent device 1, the child device 12 transmits (transfers) the ACK to the parent device 1 after SIFS.

Due to the fact that the backoff is a random value and the influence of transmission by the hidden terminal, etc., the difference is not exactly as shown in FIG. 10 and FIG. 11, but when the CSMA / CA control is applied to the conventional wireless mesh network. In comparison, in the wireless mesh network of the present embodiment, it is possible to shorten the time for each “LIFS, backoff, entry completion transmission”. That is, as a whole system, it is possible to increase the time during which messages can be transmitted and received. Even if ACK transfer from the child device 12 to the parent device 1 is treated as a message and transmitted after LIFS + backoff, the time for each “SIFS, entry completion transmission” can be shortened.

12 and 13 are diagrams for explaining the transmission timing when the handset 13 sends a message to the base unit 1 in the sequence shown in FIG. FIG. 12 and FIG. 13 show the transmission timing when the handset 13 transmits a periodic meter reading notification as an example. FIG. 12 shows the transmission timing when CSMA / CA control is applied to a conventional wireless mesh network, and FIG. 13 shows the transmission timing in the wireless mesh network of the present embodiment.

If the configuration of the conventional wireless mesh network is as shown in FIG. 1, when CSMA / CA control is applied, as shown in FIG. 12, the slave unit 13 is addressed to the slave unit 12 after LIFS + backoff. Send a periodic meter reading notification to. When receiving the periodic meter reading notification from the slave unit 13, the slave unit 12 transmits an ACK to the slave unit 13 after SIFS, and then transfers the periodic meter reading notification to the master unit 1 after LIFS + backoff. When receiving the periodic meter reading notification from the slave unit 12, the master unit 1 transmits an ACK to the slave unit 12 after SIFS.

On the other hand, in the wireless mesh network of the present embodiment, as shown in FIG. 13, when receiving the periodic meter reading notification from the slave unit 13, the slave unit 12 receives the periodic meter reading notification without transmitting an ACK. Then, after LIFS + backoff, a periodic meter reading notification is transferred to the master unit 1. When the base unit 1 receives the periodic meter reading notification, the base unit 1 transmits ACK to the handset 13 after SIFS. Thus, compared with the conventional control shown in FIG. 12, the time for each “SIFS, ACK transmission” can be shortened.

Further, the transmission timing shown in FIG. 14 can be obtained by changing a part of the CSMA / CA control applied to the wireless mesh network of the present embodiment. FIG. 14 is a diagram illustrating transmission timings in a modified example of the wireless mesh network according to the present embodiment (partly improved CSMA / CA control).

When the handset 12 receives the periodic meter reading notification from the handset 13, if the original, the fact that the transmission of the ACK addressed from the handset 12 to the handset 13 is prioritized is used, and the address is sent to the base unit 1 after SIFS. When the periodic meter reading notification is transferred, the transmission timing shown in FIG. 14 is reached. In this case, compared with the conventional control shown in FIG. 12, the time for each of “ACK transmission, LIFS, and back-off” can be shortened. Compared with the transmission timing shown in FIG. 13, the time for each “LIFS, back-off” can be shortened.

Thus, since the time required for one message transmission can be shortened, the number of slave units that can be accommodated by the master unit can be increased.

Embodiment 6 FIG.
In the first embodiment and the second embodiment, when the slave unit and the relay unit can directly receive a radio signal transmitted from the master unit or a relay unit having a high transmission output, the slave unit and the relay unit do not pass through another slave unit or the relay unit. Receiving messages and ACKs reduced the number of messages and ACKs sent. However, in consideration of the fact that the state of the wireless transmission path is likely to fluctuate, the operation of directly receiving messages and ACKs without going through other slave units or relay units is limited to cases where a certain communication quality can be obtained. May be. Whether or not a certain communication quality can be obtained is determined by, for example, an RSSI value.

For example, when the handset 13 described in the first embodiment detects that the message (for example, response / authentication request) transmitted by the base unit 1 can be directly received (see FIG. 5), If the communication quality (RSSI or the like) is less than or equal to the threshold value, the route for receiving via the slave unit 12 is selected without selecting the route for receiving directly. Similarly, the slave unit 12 described in the second embodiment detects the communication quality of the message received from the relay unit 21 when detecting that the message transmitted by the relay unit 21 can be directly received (see FIG. 7). Is equal to or less than the threshold value, the route for receiving via the slave unit 13 is selected without selecting the route for receiving directly. As described above, when the route is selected, the message and ACK can be directly received from the base unit 1 and the relay unit 21. However, when the communication quality may not be received due to the fluctuation of the electric field strength, the direct reception is selected. Without selecting from a route with better communication quality. As a result, the probability of occurrence of reselection of a route and retransmission processing due to a reception error after route selection can be reduced. Therefore, it is possible to prevent a decrease in message transfer efficiency in the wireless mesh network.

Embodiment 7 FIG.
When the positional relationship and the signal arrival area of the parent device, the child device, and the relay device are the same as in the second embodiment described above (see FIG. 6), the relay device 21 has a higher transmission output (signal arrival area 42) than each child device. ) And a transmission output (signal arrival area 41) equivalent to each slave unit, the message can be directly transmitted to the slave unit 14. On the other hand, a message can be directly transmitted to the slave unit 15 only in the case of a high transmission output. Moreover, the main | base station 1 can transmit a message directly with respect to the subunit | mobile_unit 12 in both the case of transmission output higher than each subunit | mobile_unit, and the case of the transmission output equivalent to each subunit | mobile_unit.

In such a situation, a message transmission event from the relay device 21 to the child device 14 and a message transmission event from the parent device 1 to the child device 12 occur simultaneously, and the parent device 1 and the relay device 21 are connected to the child device. When a message is transmitted with a higher transmission output, the arrival range of the message transmitted from the parent device 1 is area 2, and the arrival range of the message transmitted from the relay device 21 is area 42. At this time, the slave unit 14 can receive a message from the relay unit 21. On the other hand, since both the wireless signal transmitted from the parent device 1 and the wireless signal transmitted from the relay device 21 reach the child device 12, the message transmitted from the parent device 1 interferes with the message transmitted from the relay device 21. And cannot receive normally. As a result, since the base unit 1 cannot receive the ACK from the handset 12, it retransmits the message. However, when the transmission output of the master unit 1 and the relay unit 21 is equivalent to that of the slave unit, the reach range of the message transmitted by the master unit 1 is area 3, and the reach range of the message transmitted by the repeater 21 is area 41. . Therefore, the slave unit 14 and the slave unit 12 can receive messages from the relay unit 21 and the master unit 1 without interference, respectively. That is, since the probability of occurrence of interference can be reduced by making the transmission output of the parent device or relay device higher than that of the child device, the probability of occurrence of a reception error or retransmission due to interference can be reduced.

Considering such a case, the base unit and the relay unit according to the present embodiment change the transmission output according to the message destination. Specifically, when a message is transmitted to a child device or a relay device that can directly transmit a message to itself (two-way direct communication is possible), the transmission output is lowered. For example, when the master unit 1 transmits a message to the slave unit 11 or the slave unit 12, the transmission output is equivalent to that of the slave unit. Whether or not the transmission output is the same as that of the slave unit may be determined in transmission / reception of a message when the slave unit enters the wireless mesh network. That is, when the base unit 1 directly receives a message (peripheral search request or entry request) transmitted by a slave unit or relay device that desires to enter, the master unit 1 transmits the message to the slave unit or relay device that has transmitted this message. When transmitting a message, it is decided to lower the transmission output (equal to the slave unit). However, as shown in the sequences of FIG. 5 and FIG. 7, in order to construct an asymmetric path, it is necessary to transmit a specific message with a high transmission power.

In each of the above-described embodiments, the number of transmissions of messages and ACKs is reduced by making the transmission output of the master unit or relay unit higher than that of the slave unit. It doesn't matter. For example, the same effect can be expected by increasing the transmission output of a slave unit installed in a place with a good line of sight like the master unit and the relay unit.

In the first embodiment and the second embodiment, an example is shown in which, when a child device or a relay device enters, an entering child device or a relay device constructs an asymmetric path. Here, if an additional repeater or slave unit with high transmission output is added in an area where there are multiple slave units or repeaters that have already entered the wireless mesh network, each existing wireless terminal (participated in the wireless mesh network) In some cases, the optimum route between the parent device and the parent device changes. For example, there is a possibility that there is a slave unit or a relay unit that reduces the number of transfers through an added wireless terminal (a newly entered slave unit or relay unit). Even in such a case, it is possible to construct an asymmetric path. For example, the master unit broadcasts a message for system maintenance regularly or irregularly, and the relay unit and the slave unit use the same method as when entering in the transfer operation of the broadcast message. Thus, it can be determined whether or not an asymmetric path can be constructed. The system maintenance message is, for example, notification of system parameters. If it is determined that an asymmetric route can be constructed, a message (for example, the next periodic meter reading notification) transmitted to the parent device is notified that the route is asymmetric, and the route is updated (optimized). That's fine.

In each embodiment, an example in which a wireless mesh network is formed by a parent device, a child device, and a relay device has been described. However, a wireless mesh network may be formed only by a parent device and a child device.

As described above, the communication device according to the present invention is useful for a wireless mesh network that realizes an automatic meter-reading system.

1 master unit, 2, 3, 31, 32, 33, 34, 35, 41, 42 area (signal arrival area) 11, 12, 13, 14, 15 slave unit, 21 relay unit, 100 antenna, 101 PHY, 102 MAC, 103 CPU, 104 communication processing unit, 105 ROM, 106 RAM, 107 non-volatile memory, 108 instrument IF, 109 IF between upper devices.

Claims

A communication device that forms a wireless mesh network applied to an automatic meter reading system,
A determination means for determining whether or not direct reception of a signal transmitted by a parent device collecting meter-reading data is possible, and determining whether or not the parent device can directly receive a signal transmitted by itself,
The relay person who can directly receive the signal transmitted by the parent device and is another communication device that relays the signal transmitted by the parent device to the parent device when the parent device cannot directly receive the signal transmitted by the parent device. Determining means for determining the device;
Notifying means for notifying that the route of the signal transmitted to the parent device and the route of the signal transmitted to the parent device are different to the parent device and the relay charge device;
A communication apparatus comprising:
The communication device according to claim 1, wherein a signal is transmitted to the parent device via the relay device and a delivery confirmation of the transmitted signal is directly received from the parent device.
The communication device according to claim 1 or 2, wherein a delivery confirmation of a signal directly received from the parent device is transmitted via the relay responsible device.
4. The communication apparatus according to claim 1, wherein the communication apparatus operates as a slave unit that acquires meter reading data from a meter that performs meter reading and transmits the data to the master unit.
The communication device according to claim 1, 2 or 3, wherein the communication device operates as a relay device that relays a signal between the slave device that transmits meter reading data to the master device and the master device.
6. The communication apparatus according to claim 1, wherein an operation according to CSMA / CA control is executed.
The communication device according to any one of claims 1 to 6, wherein the determination unit determines that direct reception is possible when a certain communication quality is ensured.
A communication device that forms a wireless mesh network applied to an automatic meter reading system,
It is located on the route between itself and the master unit that collects meter reading data, and other signals that can not directly receive the signal transmitted by itself but can directly transmit the signal to itself Detecting means for detecting a high output device as a communication device;
A determination means for determining a relay charge device, which is another communication device that receives a signal addressed to the parent device transmitted by itself and transfers the signal to the high output device;
Notifying means for notifying that the route of the signal transmitted to the parent device and the route of the signal transmitted to the parent device are different from the high output device and the relay charge device;
A communication apparatus comprising:
9. The delivery confirmation for the signal addressed to the high-power device is directly received from the high-power device, and the delivery confirmation of the signal received directly from the high-power device is transmitted via the relay device. The communication device described.
10. The communication device according to claim 8, wherein the communication device operates as a slave unit that acquires meter reading data from a meter that performs meter reading and transmits the data to the master unit.
10. The communication device according to claim 8, wherein the communication device operates as a relay device that relays a signal between the slave device that transmits meter reading data to the master device and the master device.
The communication device according to any one of claims 8 to 11, wherein an operation according to CSMA / CA control is executed.
The detection means determines that another communication device that cannot directly receive a signal transmitted by itself but can directly transmit a signal in a state satisfying a certain quality with respect to itself is the high-power device. The communication device according to any one of claims 8 to 12, characterized in that:
A communication device that forms a wireless mesh network applied to an automatic meter reading system,
When a signal transmitted to the parent device is received by another communication device that can directly receive a signal transmitted by the parent device that collects meter-reading data and cannot directly transmit a signal to the parent device, the received signal Transfer means for transferring the received signal to the master unit without transmitting the delivery confirmation to the other communication device;
A communication apparatus comprising:
15. The communication apparatus according to claim 14, wherein the communication apparatus operates as a slave unit that acquires meter reading data from a meter that performs meter reading and transmits the data to the master unit.
15. The communication device according to claim 14, wherein the communication device operates as a relay device that relays a signal between the slave device that transmits meter reading data to the master device and the master device.
The communication apparatus according to claim 14, 15 or 16, wherein an operation according to CSMA / CA control is executed.
18. The communication apparatus according to claim 17, wherein the waiting time when the transfer means transfers meter-reading data is SIFS.
A communication device that forms a wireless mesh network applied to an automatic meter reading system,
When transmitting a signal to another communication device that can directly receive a signal transmitted by itself and cannot directly transmit a signal to itself, confirm delivery of the signal transmitted to the other communication device. When the other communication device receives the source signal via the relay device, the delivery confirmation of the received signal is received via the relay device that is another communication device different from the other communication device. Transmitting / receiving means for transmitting directly to the other communication device,
A communication apparatus comprising:
20. The communication device according to claim 19, wherein the communication device operates as a master unit for collecting meter reading data.
20. The communication apparatus according to claim 19, wherein the communication apparatus operates as a slave unit that acquires meter reading data from a meter that performs meter reading and transmits the data to the master unit.
The communication device according to claim 19, wherein the communication device operates as a relay device that relays a signal between the slave device that transmits meter-reading data to the master device and the master device.
The reception waiting time when receiving the delivery confirmation of the signal transmitted to the other communication device via the relay responsible device is the same as the delivery waiting time of the signal transmitted to the other communication device directly from the other communication device. The communication apparatus according to any one of claims 19 to 22, wherein the communication apparatus is longer than a reception waiting time when receiving.
The communication apparatus according to any one of claims 19 to 23, wherein an operation according to CSMA / CA control is executed.
The communication device according to any one of claims 19 to 24, wherein the transmission / reception unit reduces a transmission output when transmitting a signal to another communication device capable of two-way direct communication. .
A wireless mesh network applied to an automatic meter reading system,
One or more first communication devices;
One or more second communication devices having a higher transmission output than the first communication device;
With
When the first communication device can directly receive the signal transmitted by the second communication device, but cannot directly transmit the signal to the second communication device, the signal addressed to the second communication device A wireless mesh network characterized in that a delivery confirmation of a signal directly received from the second communication device is transmitted via another first communication device. .
A wireless mesh network applied to an automatic meter reading system,
One or more first communication devices;
One or more second communication devices having a higher transmission output than the first communication device;
With
The second communication device can directly receive a signal transmitted from the first communication device, but cannot transmit a signal directly to the second communication device. In the signal transmission to the first communication device that cannot directly transmit the signal, the relay person who is a communication device different from the first communication device confirms the delivery of the signal transmitted to the first communication device. When the first communication device receives the transmission source signal via the relay responsible device, the first communication device directly transmits a delivery confirmation of the received signal to the first communication device. Wireless mesh network.