JP2008301269A - Method of constructing communication route and communication terminal using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of constructing a communication route capable of shortening the calculation time of the communication route and reducing a memory area for recording topology data, and to provide a communication terminal. <P>SOLUTION: A communication network comprises one master and a plurality of slaves, and transmits and receives a signal between the master and the slaves by multi-hop communication. Each slave performs processing for searching an adjacent terminal capable of communicating directly. When the slave receives link information on the adjacent terminal capable of communicating directly from each slave, the master records the terminal ID of the communication terminal at a starting point side, that of the communication terminal at an end point side, and link costs indicating the communication quality level between both the terminals on a topology table TB1 comprising a one-dimensional data table based on received link information. After that, the master performs route search processing for obtaining a communication route to each slave by using the Dijkstra's algorithm based on the link information recorded on the topology table TB1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for constructing a communication route in a communication terminal using multi-hop communication and a communication terminal using the method.

  2. Description of the Related Art Conventionally, in a communication network composed of a plurality of communication terminals connected to a wireless communication network, a method for communicating with a terminal that cannot directly communicate with the own terminal by relaying a communication signal between the communication terminals is known. (So-called multi-hop communication).

  In recent years, a power line carrier communication network (hereinafter referred to as PLC network) that performs power line carrier communication (hereinafter referred to as PLC (Power Line Communication)) using a power line as a communication line between a plurality of electric devices connected to the power line. ) Is popular.

  Using such a PLC network, a power line carrier communication function is added to the watt hour meter installed in each dwelling unit of the apartment, and a PLC master unit is installed in the electrical room. There has been proposed a remote meter reading system that acquires meter reading data from a meter (PLC slave) and transmits the acquired meter reading data to a remote meter reading server through a network. In addition, a master unit is installed in the main branch board installed in the electrical room of the apartment, and a slave unit is installed in the residential distribution board of each unit. In addition, a system for monitoring and controlling the amount of electricity used in each dwelling unit by performing power line carrier communication via a branch trunk line has also been proposed. In this system, the power usage of each dwelling unit is transmitted from the slave unit to the master unit, and the power usage of each dwelling unit and the total power consumption of the entire apartment are simultaneously monitored by the master unit. If the total amount of electricity used is likely to exceed the capacity of the common electric trunk line, the master unit sends a usage restriction command to the slave unit of the dwelling unit that consumes a lot of electricity, and the slave unit is set in advance. Products are automatically shut down to limit the amount of electricity used in the entire apartment. In these systems using the PLC network, the wiring length between the communication terminals is long and the number of communication terminals connected is large, so that the communication terminals at a communicable distance relay the communication signal, Multi-hop communication that performs communication with a parent device is performed (see, for example, Patent Document 1).

  By the way, in the wireless communication network described above, since the terminal moves within the network, the network topology tends to change, and it is necessary to reconstruct the communication route between the terminals in response to the change in topology. It was. Also, in PLC networks, communication may be impossible due to the effects of noise generated by electrical equipment because communication is performed via the power line, and the power plug from the electrical equipment must be plugged in and unplugged. Therefore, there is a feature that the network topology is easy to change because the connection state of the electrical equipment to the power line changes, and there is an electrical equipment that cannot make a call, and communication between each terminal responds to the change in topology. There was a need to rebuild the route.

Therefore, in these communication networks, it is necessary to search for a communication route having the best communication quality level between terminals every time a predetermined time elapses, and an algorithm called Dijkstra algorithm is used to efficiently search for a communication route. (For example, refer nonpatent literature 1).
JP 2006-67557 A Nishimaru Yasuyuki, Sato Fumiaki; “QoS Multicast Distribution Tree Construction Method”; Information Processing Society of Japan Research Report Vol.2003, No.34; Information Processing Society of Japan; March 20, 2003

  In the communication network described above, in order to establish a communication route between the parent device and each child device, each communication terminal notifies the existence of its own terminal (Hello Packet, hereinafter abbreviated as H packet). After searching for neighboring terminals that can communicate directly with each other, a topology notification message for notifying the search result to the parent device is returned to the parent device, and in the parent device, from the received topology notification message, The terminal ID of the communication terminal on the start side and the terminal side on which the link is established and the link cost indicating the communication quality level between both terminals are recorded in the topology table TB1 ′ as shown in FIG. ing. Then, based on the link information recorded in the topology table TB1 ′ (information on adjacent terminals that can be directly communicated with each child device), the parent device constructs a communication route to each child device using the Dijkstra algorithm. It has become.

  By the way, the topology table TB1 ′ shown in FIG. 1C is composed of a two-dimensional data table in which, for example, the terminal IDs of the communication terminals on the start point side are arranged in a row and the terminal IDs of the communication terminals on the end point side are arranged in a row. The link cost is recorded at the grid where the column corresponding to the communication terminal and the row corresponding to the communication terminal on the end point intersect. In addition, a portion including “−” in the grid indicates that a link is not established between corresponding terminals. Here, the same value is recorded in the cell in which the communication terminal on the start point side and the communication terminal on the end point side are exchanged (the link cost that enters the cell of m rows and n columns and the cell of n rows and m columns). In the topology table TB1 ′ shown in FIG. 1C, the table size is reduced by recording data in only one area across the diagonal line, but the link is established. A memory area for recording the link cost is secured even between terminals that are not connected. For this reason, the memory area is wasted, and it is necessary to prepare a RAM having a large storage capacity compared to the memory area that is actually used, resulting in a high cost. In addition, it takes time to search for a communication route using the Dijkstra algorithm, and as the number of terminals increases, the time required for the route search becomes longer. Therefore, there has been a demand for shortening the communication route search time.

  The present invention has been made in view of the above problems, and an object of the present invention is to establish a communication route and a communication terminal capable of reducing a memory area for recording topology data. Is to provide. Further, an object of the present invention is to provide a method for constructing a communication route in which a memory area for recording topology data is reduced while reducing the time required for searching for a communication route. is there.

  To achieve the above object, according to the present invention, one of a plurality of communication terminals constituting a communication network is a master unit and the rest is a slave unit, and the master unit includes the master unit and each slave unit. Between the master unit and the slave unit by reading the communication route to the desired slave unit from the storage unit storing the communication route between and the neighboring unit according to the communication route. This is a communication route construction method in which the base unit receives link information related to adjacent terminals that can communicate directly from each slave unit and establishes a communication route to each slave unit based on the received link information. Then, from each slave unit, a link information receiving step for receiving link information related to an adjacent terminal with which the slave unit can directly communicate, and based on the received link information, the terminal ID of the start-point side communication terminal, The terminal ID of the communication terminal, and Based on the topology recording step for recording the link cost indicating the communication quality level between terminals in the topology table consisting of a one-dimensional data table and the link information recorded in the topology table to each slave unit using the Dijkstra algorithm And a communication route construction step for obtaining a communication route.

  According to the invention of claim 2, in the invention of claim 1, when obtaining a communication route to each child device using the Dijkstra algorithm in the communication route construction step, a predetermined communication route from the parent device to the target child device is specified. If a communication route that is higher than the communication quality can be searched, the communication route is determined as the communication route to the child device, and the communication route to the child device is searched before searching all communication routes to the child device. This is characterized in that the search is terminated.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the topology table is sorted so that the magnitude relation between the terminal ID of the communication terminal on the start point side and the terminal ID of the communication terminal on the end point side is a constant relationship. The communication route construction step is executed in the state that has been made.

  According to a fourth aspect of the present invention, there is provided the communication route construction step according to any one of the first to third aspects, wherein the terminal IDs of the communication terminals on the start side stored in the topology table are sorted in ascending or descending order. It is characterized by performing.

  According to a fifth aspect of the invention, in the fourth aspect of the invention, the communication route construction step is executed in a state where the terminal IDs of the terminal side communication terminals stored in the topology table are sorted in ascending or descending order. Features.

  The invention of claim 6 is the invention according to any one of claims 1 to 5, wherein in the topology recording step, at least one of the terminal IDs of the communication terminals on the start point side or the end point side is arranged in ascending order or descending order. The terminal ID and link cost of the communication terminal on the side and the end point side are recorded in the topology table.

  According to the seventh aspect of the present invention, one of a plurality of communication terminals constituting a communication network is a master unit and the rest is a slave unit, and the master unit stores a communication route between the master unit and each slave unit. The communication on the parent device side that performs communication between the parent device and the child device by reading out the communication route to the desired child device from the storage unit and exchanging communication signals between adjacent terminals according to the communication route. A link information receiving means for receiving link information related to an adjacent terminal that can be directly communicated with each slave unit, and a terminal ID of the communication terminal on the start point side based on the received link information, Recorded in the sorted topology table, table processing means for recording the terminal ID of the communication terminal on the end point side and the link cost indicating the communication quality level between both terminals in a topology table composed of a one-dimensional data table Based on link information, characterized by comprising a communication route constructing means for obtaining a communication route to the handset by using the Dijkstra algorithm.

  According to the invention of claim 1, based on the link information received from each slave unit, the terminal ID of the communication terminal on the start point side, the terminal ID of the communication terminal on the end point side, and the communication quality level between both terminals are determined. Since the link cost shown is recorded in a topology table consisting of a one-dimensional data table, the link cost is added to a topology table consisting of a two-dimensional data table with the start-point side communication terminals in a row and the end-point side communication terminals in a row. Compared with the case of recording a network, a memory area for recording the link cost between terminals for which no link has been established is not wasted, and a method for constructing a communication route with a reduced storage capacity for recording topology data is provided. Can be realized.

  According to the invention of claim 2, when a communication route having a predetermined communication quality or higher can be searched as a communication route from the parent device to the target child device, the communication route is determined as a communication route to the child device. Therefore, it is possible to secure a communication route higher than the predetermined communication quality as a communication route between the parent device and the child device, and search for all communication routes to the child device, from which the communication quality is the highest. It is possible to search for a communication route in a shorter time than when selecting a good communication route.

  According to the invention of claim 3, the communication route is constructed in a state in which the topology table is sorted so that the magnitude relationship between the terminal ID of the communication terminal on the start point side and the terminal ID of the communication terminal on the end point side is a constant relationship. Since the steps are executed, when searching for link information of a desired communication terminal, the search is first performed in order only on the start point side, and the end point side is searched only when the start point side matches, thereby shortening the search time. Can do.

  According to the invention of claim 4, since the communication route construction processing is performed in a state where the terminal IDs of the communication terminals on the starting point side are sorted in ascending order or descending order, the link information of the desired communication terminal is searched. The search time can be shortened.

  According to the invention of claim 5, since the communication route construction processing is performed in a state where the terminal IDs of the communication terminals on the end point side are sorted in ascending or descending order, the link information of the desired communication terminal is searched. The search time can be shortened.

  According to the invention of claim 6, the terminal ID and the link cost of the communication terminal on the start point side and the end point side are set so that at least one of the terminal IDs of the communication terminals on the start point side or the end point side is arranged in ascending order or descending order. Since it is recorded in the topology table, it is not necessary to perform processing for sorting terminal IDs when constructing a communication route, and the time required for searching for a communication route can be further shortened.

  According to the invention of claim 7, on the basis of the link information received from each slave unit by the link information receiving means, the table processing means includes a terminal ID of the communication terminal on the start point side, a terminal ID of the communication terminal on the end point side, In addition, since the link cost indicating the communication quality level between the two terminals is recorded in the topology table composed of a one-dimensional data table, the two-dimensional data is taken in the row of the communication terminals on the start side and the communication terminals on the end side. Compared with the case where the link cost is recorded in the topology table consisting of the data table, the memory area for recording the link cost between the terminals where the link has not been established is not wasted, and the memory for recording the topology data is stored. A communication terminal capable of reducing the capacity can be realized.

  Hereinafter, an embodiment in which a communication route construction method according to the present invention is applied to a communication network that performs communication by power line carrier communication will be described with reference to the drawings.

(Embodiment 1)
Embodiment 1 of this invention is demonstrated based on drawing. FIG. 16 is a schematic configuration diagram of a power line carrier communication network (hereinafter abbreviated as “PLC network”) 1. This PLC network 1 is used in, for example, a building such as an apartment house, and is configured by connecting a plurality of communication terminals 2 to a power line L, and one of the plurality of communication terminals 2 is connected to a parent device A. , And the rest are set as slave units Bn (n = 1, 2, 3,...).

  In the PLC network 1, a predetermined communication protocol (for example, SCP, Echonet, etc.) is transmitted between the parent device A and the child device Bn with the adjacent terminal 2 (the parent device A or the child device Bn) at a communicable distance. Power line carrier communication is performed, and the parent device A collects predetermined information from the child device Bn, and remote monitoring of the child device Bn is performed. Here, in the present network 1, communication is performed directly or indirectly between the parent device A and each child device Bn, and the child device Bn that cannot directly communicate with the parent device A is another child within a communicable distance. Communication with the parent device A is performed by sequentially relaying communication signals to the device Bn.

  FIG. 17 is a block diagram of the communication terminal 2 (master device A or slave device Bn) used in this embodiment. In the present embodiment, the same communication terminal 2 is used for the parent device A and the child device Bn. For example, any one of the communication terminals 2 uses a setting means (not shown) such as a jumper switch or a changeover switch. It is made to function as the main | base station A by setting to the side of a machine, and it is made to function as the subunit | mobile_unit Bn by setting to the subunit | mobile_unit side using the setting means in other communication terminals 2.

  The communication terminal 2 includes a storage unit 3, a power line carrier communication interface unit (hereinafter abbreviated as “PLC interface unit”) 4, and a control unit 5. The storage unit 3 includes a non-volatile memory such as a ROM, a rewritable non-volatile memory such as an EEPROM, and a volatile memory such as a RAM, and stores a communication route and link information related to a neighboring terminal capable of communication. A table storage unit 3 a is provided, and various programs such as a control program for operating the communication terminal 2, information necessary for executing each program, and the like are stored.

  The table storage unit 3a is an area for storing data in a table format. When this terminal is the base unit A, communication for registering all communication routes between terminals built in the network in the table storage unit 3a. A route table and a topology table for recording information (link information) of adjacent terminals with which each terminal can directly communicate are stored. On the other hand, when the terminal is a slave unit Bn, the table storage unit 3a has an adjacent terminal 2 (master unit A or another slave unit Bn) with which the slave unit Bn can communicate, and the slave unit Bn and the adjacent terminal 2 A communication cost value (hereinafter referred to as a link cost) indicating a communication quality level between (the parent device A or another child device Bn) and the child device Bn and the parent device A via the adjacent terminal 2 A communicable terminal table D representing a communication cost value (hereinafter referred to as a route cost) indicating a communication quality level is stored.

  Table 1 shows an example of the communicable terminal table D. In this data table D, the terminal ID assigned to the adjacent terminal 2 (master A or other slave Bn) that can directly communicate with the own terminal, The terminal type data indicating the type of the adjacent terminal 2 (base unit A or other slave unit Bn), the link cost indicating the communication quality level between the adjacent terminal 2 and the own terminal, the adjacent terminal 2 and the base unit A And the terminal ID indicating the first hop, the second hop,..., The N hop communication terminal 2 from the own device in the communication route from the adjacent terminal 2 to the base unit A are stored in association with each other. ing. The above communication cost values (link cost and route cost) represent the received signal strength of a communication signal received from an adjacent terminal at several levels. The smaller the value, the smaller the attenuation of the communication signal. This indicates that the communication quality level is high. Further, the route cost from the own terminal to the parent device A is a value obtained by adding the higher-order route cost between the adjacent terminal and the parent device A to the link cost between the own terminal and the adjacent terminal.

  Here, since the PLC network 1 performs communication through the power line L, noise generated from other home appliances connected to the power line L, reduction in impedance of the power line L due to connection of other home appliances, and the like, There is a risk that the transmission environment will deteriorate and the communication error rate will increase. The transmission environment of the PLC network 1 dynamically changes depending on whether the home appliance is plugged in or unplugged from the power outlet or the home appliance is movable. For this reason, in the PLC network 1, the network topology is not fixed and tends to change, and even if the network topology changes, the parent device A and the child device Bn can communicate well with each other. It is necessary to periodically search for a communication route between the device A and each child device Bn to construct an optimum communication route.

  That is, the control unit 5 of the communication terminal 2 includes, for example, a microprocessor and its peripheral circuits, and performs processing for searching for a communication route between the parent device A and the child device Bn [that is, processing for searching for an adjacent terminal] In order to execute a process for notifying the base unit of a search result (link information) or a process for searching for a route based on link information on the base unit side], a communication processing unit 5a, a table processing unit 5b, A hello packet transmission timer unit (hereinafter abbreviated as H packet transmission timer unit) 5c and a link notification packet transmission timer unit 5d are provided.

  The communication processing unit 5a transmits / receives a communication signal by power line carrier communication to / from another communication terminal 2 using the PLC interface unit 4, and performs an operation described later, thereby performing a communication between the parent device A and the child device Bn. A communication route construction process (consisting of a route search process and a route selection process) for constructing a communication route is performed. FIG. 18A shows a basic format of a communication packet exchanged between the communication terminals 2 (base unit A and handset Bn). The transmission terminal ID of the source communication terminal 2 and the reception side communication terminal are shown. 2 reception terminal ID, message type, and data (message dependent part) corresponding to the message type. The message type includes a hello packet for notifying the existence of the terminal itself and the communication route, a link notification packet for notifying neighboring terminal information to the base unit, and a communication error during relay when sending a normal packet. There is a route error packet to be transmitted in the case of. FIG. 18B shows a packet format of a hello packet (H packet), a transmission terminal ID, a reception terminal ID, data “Hello” indicating a message type, and a transmission source terminal type (master A or child). Data indicating the type of the machine Bn) and at least data indicating the communication route from the own machine to the parent machine A obtained on the slave side, and if there is a terminal with a lost link, the link is lost indicating the address. It is configured with a terminal address added. FIG. 18C shows the packet format of the link notification packet. The transmission terminal ID, the reception terminal ID, the data “link notification” indicating the message type, and from the own device to the parent device A obtained on the child device side. Route information indicating the communication route of the terminal and adjacent terminal information regarding the adjacent terminal capable of direct communication. When there is a terminal with a lost link, a link lost terminal address indicating the address is added. FIG. 18D shows the packet format of the route error packet. The transmission terminal ID, the receiving terminal ID, the data “route error” indicating the message type, and the route indicating the communication route from the own device to the parent device A. It includes information and information indicating an error location where a communication error has occurred.

  The table processing unit 5b manages a data table (communication route table, topology table, communicable terminal table D, etc.) stored in the table storage unit 3a.

  The H packet transmission timer unit 5c has time measuring means for measuring time, and gives a trigger signal to the communication processing unit 5a every time a predetermined transmission time elapses to cause the communication processing unit 5a to transmit an H packet. That is, H packets are transmitted at predetermined transmission time intervals.

  The link notification packet transmission timer unit 5d also has a time measuring means for measuring time, and gives a trigger signal to the communication processing unit 5a every time a predetermined transmission time elapses to cause the communication processing unit 5a to transmit a link notification packet. That is, the link notification packet is transmitted at a predetermined transmission time interval.

  In each communication terminal 2, when a signal indicating the arrival of transmission timing is output from the H packet transmission timer unit 5c to the communication processing unit 5a, the communication processing unit 5a creates an H packet and transmits it to the power line L by broadcast. The communication quality level (link cost) with the adjacent terminal capable of receiving the H packet and the information on the upper route of the adjacent terminal are acquired.

  Here, processing for constructing a communication route in the communication network shown in FIG. This communication network is composed of one parent device A and a plurality of (for example, six) child devices B1 to B6. The terminal ID of the parent device A is 100, and the terminal IDs of the child devices B1 to B6 are 101 to 101 respectively. 106 is set. In FIG. 3A, terminals connected by a solid line indicate terminals that can directly communicate with each other, and a number displayed in the vicinity of a line connecting the two terminals indicates a link cost between the two terminals.

  First, when a signal indicating the arrival of transmission timing is output from the H packet transmission timer unit 5c to the communication processing unit 5a in the base unit A, the communication processing unit 5a creates the above H packet and transmits it to the power line L by broadcast. To do. At this time, in the H packet transmitted from the parent device A, the transmission terminal ID is ID = 100 of the own device, the reception terminal ID is broadcast, the message type is “Hello”, and the terminal type is the parent device.

  It is understood that the communication processing unit 5a of the slave units B1 and B2 can directly communicate with the master unit A by receiving the H packet transmitted from the master unit A, and from the received signal strength of the H packet. The communication quality level (link cost) with the parent device A can be calculated. And since it became clear in the communication processing part 5a of each subunit | mobile_unit B1, B2 that it can communicate directly with the main | base station by receiving the H packet from the main | base station A, the above-mentioned H packet is produced, and power line L is broadcast. Send to. At this time, the H packet transmitted from the child device B1 has the transmission terminal ID of own device ID = 101, the reception terminal ID is broadcast, the message type is “Hello”, the terminal type is the child device, and the parent device requested by the child device. The route to the machine is the child machine B1 (101) → the parent machine A (100), and the route cost is 3. The H packet transmitted from the child device B2 is transmitted to the parent device that the transmission terminal ID is 102, the reception terminal ID is broadcast, the message type is “Hello”, the terminal type is the child device, and the child device is requested. The route is slave unit B2 (102) → base unit A (100), and the route cost is 2.

  The communication processing unit 5a of the slave unit B3 receives the H packet transmitted from the slave unit B1, and thus can directly communicate with the slave unit B1, and the H packet from the slave unit B1. The link cost (= 5) with the handset B1 is obtained based on the received signal level. At this time, in the communication processing unit 5a of the child device B3, only the communication route via the child device B1 can be found as a communication route connecting the own device and the parent device, and the route cost of this communication route is the link cost of each hop. The sum is (= 8). Note that the H packet transmitted from the slave unit B3 has a transmission terminal ID of own device ID = 103, a reception terminal ID of broadcast, a message type of “Hello”, a terminal type of slave unit, and a communication route to the master unit. The route cost is 8 in the sub unit B3 (103) → the sub unit B1 (101) → the main unit A (100).

  In addition, the communication processing unit 5a of the slave unit B4 can directly communicate with the slave units B1, B2, and B3 by receiving the H packets transmitted from the slave units B1, B2, and B3. Also, based on the received signal level of the H packet from each slave unit, the link cost between each slave unit (link cost is 2 between slave units B1, link cost is 4 between slave units B2, and slave unit B3 The link cost is 5). At this time, the communication processing unit 5a of the child device B4 can find three communication routes respectively passing through the child devices B1, B2, and B3 as communication routes connecting the own device and the parent device, and the route cost of each communication route is Since the link cost of each hop is the sum, it can be seen that the route cost via the child device B1 is 5, the route cost via the child device B2 is 6, and the route cost via the child device B3 is 13. Here, the smaller the value of the route cost is, the better the communication quality level is. Therefore, the route cost via the child device B1 is the smallest. Therefore, the communication processing unit 5a of the child device B0 A communication route of “child device B4 → slave device B1 → parent device A” is selected as a communication route between and a H packet for notifying the selected communication route is created and transmitted by broadcast. The H packet transmitted from the child device B4 has a transmission terminal ID of own device ID = 104, a reception terminal ID of broadcast, a message type of “Hello”, a terminal type of the child device, and a communication route to the parent device. The route cost is 5 in the sub unit B4 (104) → the sub unit B1 (101) → the main unit A (100).

  The other handset B5 (105) and B6 (106) can also detect the adjacent terminal capable of direct communication by receiving the H packet from the other handset, and the communication route from the adjacent terminal to the base unit A and its Based on the higher-order route cost and the link cost between the adjacent terminals, the communication route from the own terminal to the parent device A and its route cost are obtained, and broadcast transmission is performed using H packets.

  As described above, each of the slave units B1 to B6 can select a communication route with the master unit A, and each slave unit Bn obtains information on adjacent terminals that can communicate directly by transmitting and receiving H packets. When a trigger signal is given from the link notification packet transmission timer unit 5d, the link information related to the adjacent terminal is stored in the link notification packet and transmitted to the parent device A.

  For example, when the slave unit B4 transmits a link notification packet, the link notification packet has a transmission terminal ID of own device ID = 104, a reception terminal ID of slave unit B1 ID = 101, and a message type of “link notification”. The route to the parent device is the child device B4 (104) → the child device B1 (101) → the parent device A (100), the route cost is 5, and the adjacent terminal information is the child device B1 (ID = 101, link cost 2). , Slave unit B2 (ID = 102, link cost 4) and slave unit B3 (ID = 103, link cost 5). The communication processing unit 5a of the slave unit B1 that has received the link notification packet can know that it should be relayed to the master unit A by referring to the route information included in the link notification packet. Based on the link notification packet, a link notification packet to be transmitted to base unit A is created and transmitted to base unit A. Here, the link notification packet transmitted by the child device B1 has a transmission terminal ID of own device ID = 101, a reception terminal ID of the parent device ID = 100, a message type of “link notification”, and a route to the parent device. The child device B4 (104) → the child device B1 (101) → the parent device A (100) has a route cost of 5, the adjacent terminal information is the child device B1 (ID = 101, link cost 2), and the child device B2 (ID = 102, link cost 4), and slave unit B3 (ID = 103, link cost 5). When the base unit A receives this link notification packet, it can be seen from the route information to the base unit included in the link notification packet that the transmission source is the base unit B4 (ID = 104). And a topology table TB1 as shown in FIG. 3B is created based on the neighboring terminal information included in the packet. Since this link notification packet is transmitted from each slave unit Bn at a fixed time interval, the master unit A receives the link notification packet from each slave unit Bn, and thus the communication route between each slave unit Bn and The adjacent terminal information of each slave unit Bn can be acquired.

  Thus, the communication processing unit 5a (link information receiving means) of the parent device A acquires the information of the adjacent terminals with which each child device Bn can directly communicate by receiving the link notification packet from each child device Bn. (Link information receiving step), the table processing unit 5b is used to store link information related to the adjacent terminal of each slave unit Bn in the topology table TB1. Note that the data of the communication route included in the link notification packet is a communication route obtained within a range in which each slave unit can transmit and receive the H packet, and includes only one route data. There is a possibility that the communication route is disconnected, and the base unit A searches for a communication route to each slave unit Bn by performing a search process described later based on the link information recorded in the topology table TB1. I am doing so.

  Here, in the conventional communication network, based on the topology notification message transmitted from the slave unit Bn by the master unit A, the link information stored in this message (the terminal ID and the link of the communication terminal 2 on the start point side and the end point side) (Consisting of cost) is recorded in the topology table TB1 ′ shown in FIG. This topology table TB1 ′ is composed of a two-dimensional data table in which the communication terminals on the start point side are arranged in a row and the communication terminals on the end point side are arranged in a row. Therefore, when the number of communication terminals is n, the link cost is reduced. The memory area to be recorded is [(n-1)! There is a problem that a memory area for recording the link cost between terminals for which a bidirectional link cannot be established is wasted.

  Therefore, in the present embodiment, the link information stored in the topology notification message from the slave unit Bn and transmitted by the table processing unit 5b (table processing means) of the master unit A as shown in FIG. It is stored in the topology table TB1 (topology recording step). In FIG. 1 and FIG. 2, the start point node and the end point node are indicated by single-digit numbers for the sake of simplicity.

  The topology table TB1 used in the present embodiment includes a terminal ID of a communication terminal (start node) on the start side, a terminal ID of a communication terminal (end node) on the end side, and a link cost indicating a communication quality level between both terminals. It consists of a one-dimensionally recorded table, and only requires a memory area for which link information is notified. Compared to a case where a predetermined number of memory areas are secured in advance as in the topology table TB1 ′ shown in FIG. The memory area can be made smaller and there is no wasted memory area, so the memory area can be used effectively, and it is not necessary to prepare a memory with a larger storage capacity than necessary. There is an advantage that can be prevented.

  Note that the communication processing unit 5a of the parent device A executes a route search process (to be described later) for searching for a communication route to each child device Bn based on the link information recorded in the topology table TB1. As shown in FIG. 1B, the magnitude relationship between the terminal ID of the start node and the terminal ID of the end node is constant (for example, (terminal ID of the start node) <( It is preferable to record in the topology table TB1 so as to be the terminal ID of the end node))). Here, when searching for a link (terminal) communicable with the terminal to be searched, if there is no fixed relationship between the size of the terminal ID of the start node and the terminal ID of the end node, the topology Both the start-side ID and the end-side ID of all link information recorded in the table TB1 must be searched, so that (start-point node ID) <(end-point node ID). If recorded in the topology table TB1, only one of the start point and the end point needs to be searched, and there is an advantage that the time required for calculating the communication route can be shortened.

  Further, when the terminal ID of the start node or the terminal ID of the end node are not sorted in ascending or descending order as in the topology table TB1 shown in FIG. 2A, to search for link information of a desired terminal, Since it is necessary to search in order from the first record, it takes time. As shown in FIG. 2B, the terminal IDs of the start node are sorted in ascending order to search for link information of a desired terminal. Since a search algorithm such as a partial search can be used, the terminal search process can be performed efficiently. Further, as shown in FIG. 2C, after sorting the terminal IDs of the start node as the first key in ascending order, the terminal IDs of the end node are sorted in the ascending order using the second key, so that link information of the desired terminal is obtained. The process of searching for can be performed more efficiently. In the topology table TB1 shown in FIGS. 2B and 2C, the start point node or the end point node is sorted in ascending order. However, it may be sorted in descending order, and processing for searching link information of a desired terminal is performed. It can be done efficiently. In the topology table TB1 shown in FIG. 2B, the terminal IDs of the start node are sorted in ascending order, but the terminal IDs of the end node may be sorted in ascending order, and the terminal IDs of the end node are After sorting in ascending order as one key, the terminal IDs of the start node may be sorted in ascending order as the second key. Further, when the communication processing unit 5a of the parent device A records the terminal IDs and link costs of the start node and the end node in the topology table TB1 using the table processing unit 5b, the terminal IDs are arranged in ascending or descending order. If it is recorded in the topology table TB1 after sorting, the link information of the desired terminal can be searched in a short time, but the link information is recorded in the topology table TB1 in the order in which the topology notification messages are received. In addition, when searching for link information of a desired terminal, the search may be performed after sorting the terminal IDs in ascending order or descending order.

  As described above, when the parent device A receives the topology notification message from the child device Bn configuring the network and records the link information in the topology table TB1 in the storage unit 3, the communication processing unit 5a of the parent device A Based on the link information recorded in the topology table TB1, (communication route construction means) performs route search processing for obtaining a communication route to each child device using the Dijkstra algorithm (communication route construction step).

  Here, route search processing by the base unit A will be described with reference to FIGS. Each terminal performs a search process for adjacent terminals, stores link information in a link notification packet, and transmits the link information to the base unit A (100), so that the link information of each terminal is stored in the topology table TB1 of the base unit A. It is assumed that it is recorded (see FIG. 3B). FIG. 5A shows a communication route calculation table TB2 prepared in the table storage unit 3a of the parent device A. The calculation table TB2 is a table used in the process of searching for a communication route. In the calculation table TB2, the terminal ID of the previous hop and the route construction terminal are set for the terminal IDs 100 to 106 of each terminal. A flag Visit indicating whether or not, a hop count HOP from the parent device A, and a route cost from the parent device A are recorded.

  FIG. 4 is a flowchart of route search processing by the base unit A. First, the communication processing unit 5a of the base unit A determines its own device (terminal ID = 100) as a route construction terminal (S1), and selects the route construction terminal. The search target is determined, and the flag Visit of the own device (terminal ID = 100) is set to TRUE (◯) as shown in FIG. 5B (S2). Then, the communication processing unit 5a of the base unit A designates the start point node as a search target terminal ID (= 100) and the end point node IDs in order of 101, 102, 103,. It is searched whether or not the corresponding link exists in the topology table TB1 (S3). Here, if the links that can communicate with the search target terminal are searched in order from the top of the topology table TB, the search takes a very long time especially when the number of topologies is large. In the topology table TB1 as described above, since the terminal IDs of the start point node or end point node are sorted in ascending or descending order, the search is first performed after searching the start point node using a binary search, and then extracted. By searching for a link whose end point node matches from the generated links, the time required for the search can be considerably shortened.

  If the link can be found in the topology table TB1 in S3, the route cost RC1 of the link is compared with the route cost RC recorded in the calculation table TB2 (S4), and the route cost RC1 discovered this time is calculated. If it is smaller than the route cost RC recorded in the table TB2 (RC> RC1), the terminal ID of the previous hop, the route cost, and the number of hops HOP are written in the operation table TB2 (S5), and the process returns to S2 continue. On the other hand, if the route cost RC1 discovered this time in S4 is equal to or higher than the route cost RC recorded in the calculation table TB2 (RC ≦ RC1), the communication processing unit 5a does not perform the route cost writing process to the calculation table TB2. , Return to S2 and continue processing. When the route cost is not recorded in the calculation table TB2, the route cost RC1 discovered this time is written in the calculation table TB2. Here, when the terminal to be searched is a master unit (terminal ID = 100), the link is connected to the terminals having terminal IDs 101 and 102, and the hop count HOP (= 1) between the two terminals and the previous hop. The terminal ID and the route cost RC [terminal (101) is 3, terminal (102) is 2] are recorded in the calculation table TB2 (see FIG. 5C).

  When all the communicable links for the search target terminal have been searched, the communication processing unit 5a of the base unit A determines from the calculation table TB2 a terminal whose flag Visit is FALSE (a terminal having no circle in the Visit column). ) Is present (S6), and if it exists, the terminal with the lowest root cost is determined as the search target among the terminals having the flag Visit of FALSE, and the flag Visit of this terminal is set to TRUE ( ○) (S7), the process returns to S3, and the above-described processing is repeated.

  Here, among the terminals (101 to 106) whose flag Visit is FALSE, the terminal with the lowest root cost is the terminal whose terminal ID is 102 (hereinafter referred to as the terminal (102)), so the communication processing unit 5a. Sets this terminal as a search target, sets the flag Visit of the terminal (102) to TRUE (◯) as shown in FIG. 6A, and sets the start node to the search target terminal ID (= 102). As well as specifying the terminal ID of the terminal node in order to the terminal IDs 101, 103, 104, 105, and 106 of the terminals whose flag Visit is not TRUE (◯), the corresponding link exists in the topology table TB1. Whether or not (S3). If the corresponding link can be found in the topology table TB1, the route cost RC1 of the corresponding link discovered this time (terminal ID 104, 105, 106) and the route cost RC of the terminal recorded in the calculation table TB2 are compared. If RC> RC1, the previous hop terminal ID, route cost, and hop count HOP (= 2) are overwritten in the calculation table TB2 (see FIG. 6B). Since the route cost is a communication cost value between the own device and the parent device, the route cost is a total value of the link costs of each hop. For example, in the terminal (104), the total value of the link cost (= 2) between the terminal (100) and the terminal (102) and the link cost (= 4) between the terminal (102) and the terminal (104) ( = 6).

  When the detection of all communicable terminals for the terminal (102) is completed, the communication processing unit 5a determines the terminal (101) with the lowest root cost among the terminals (101, 104 to 106) whose flag Visit is FALSE. Is set as a search target, and the flag Visit of the terminal (101) is set to TRUE (O) as shown in FIG. 7A, and then the start node is designated as the search target terminal ID (= 101). The terminal ID of the terminal node is specified in order to the terminal IDs 103, 104, 105, and 106 of the terminals whose flag Visit is not TRUE (O), and a search is performed as to whether the corresponding link exists in the topology table TB1. (S3). Then, if the corresponding link can be found in the topology table TB1, the route cost RC1 of the corresponding link discovered this time (terminal having terminal IDs 103 to 105) is compared with the route cost RC of the terminal recorded in the operation table TB2, If RC> RC1, the previous hop terminal ID, the route cost, and the hop count HOP (= 2) are overwritten in the calculation table TB2 (see FIG. 7B). Here, since no data is recorded in the calculation table TB2, the terminal (103) records the route cost of the link found this time, the terminal ID of the previous hop, and the number of hops in the calculation table. Further, the terminal (104) has the route cost RC1 (= 5) of the link discovered this time (the terminal ID of the previous hop is 101) than the route cost RC (= 6) stored in the calculation table TB2. Since it is small, the route cost of the link discovered this time, the terminal ID of the previous hop, and the number of hops are recorded in the calculation table. On the other hand, the route cost of the terminal terminal (105) is equal to or higher than the route cost RC stored in the calculation table TB2 for the link discovered this time (the terminal ID of the previous hop is 101). The data in the table TB2 is left as it is.

  Next, when all the terminals that can communicate with the terminal (101) have been detected, the communication processing unit 5a determines the terminal (104 with the lowest root cost among the terminals (103 to 106) in which the flag Visit is FALSE. ) Is set as the search target, and the flag Visit of the terminal (104) is set to TRUE (O) as shown in FIG. 8A, and then the start node is designated as the search target terminal ID (= 104). Then, the terminal ID of the terminal node is designated in order to the terminal IDs 103, 105, and 106 of the terminals whose flag Visit is not TRUE (◯), and a search is performed as to whether the corresponding link exists in the topology table TB1 ( S3). In this case, since the corresponding link cannot be found in the topology table TB1, the data in the operation table TB2 is left as it is (see FIG. 8B).

  When the detection of all communicable terminals is completed for the terminal (104), the communication processing unit 5a determines the terminal (106 with the lowest root cost among the terminals (103, 105, 106) whose flag Visit is FALSE. ) Is set as the search target, and the flag Visit of the terminal (106) is set to TRUE (O) as shown in FIG. 9A, and then the start point node is designated as the search target terminal ID (= 106). Then, the terminal ID of the terminal node is specified in order to the terminal IDs 103 and 105 of the terminals whose flag Visit is not TRUE (◯), and whether or not the corresponding link exists in the topology table TB1 is searched (S3). . If the corresponding link can be found in the topology table TB1, the route cost RC1 of the relevant link (terminal (105)) found this time is compared with the route cost RC of the terminal recorded in the calculation table TB2. In this case, the route cost of the terminal (105) is higher than the route cost RC stored in the calculation table TB2 because the route cost RC1 of the link discovered this time (the terminal ID of the previous hop is 106) is higher than the route cost RC. The data in the table TB2 is left as it is (see FIG. 9B).

  When the detection of all communicable terminals for the terminal (106) is completed, the communication processing unit 5a determines the terminal (103) with the lowest root cost among the terminals (103) and (105) whose flag Visit is FALSE. Is set as a search target (in this case, the route cost is the same value, so the terminal ID is determined to be smaller), and the flag Visit of the terminal (103) is set to TRUE (◯) as shown in FIG. Then, the start point node is designated as the search target terminal ID (= 103), and the end point node ID is designated as the terminal ID 105 of the terminal whose flag Visit is not TRUE (◯). It is searched whether or not the link exists in the topology table TB1 (S3). In this case, since the corresponding link cannot be found in the topology table TB1, the data in the operation table TB2 is left as it is (see FIG. 10B).

  When the detection of all communicable terminals for the terminal (103) is completed, the communication processing unit 5a sets the terminal (105) whose flag Visit is FALSE as a search target, as shown in FIG. 11 (a). After setting the flag Visit of the terminal (105) to TRUE (◯), the start point node is designated as the search target terminal ID (= 105), but there is no terminal whose flag Visit is not TRUE (◯). Since the end point node cannot be specified and the process is terminated without performing the corresponding link search process, the data in the calculation table TB2 remains as it is (see FIG. 11B). When the processing for the terminal (105) is completed, the flag Visit of all terminals becomes TRUE, so the communication processing unit 5a determines that the communication route of all terminals can be set, and uses the table processing unit 5b. The information in the calculation table TB2 is reflected in the communication route table of the storage unit 3 (S8), the route search process is terminated, and thereafter, the parent device A and each child device Bn using the communication route recorded in the communication route table. Communication signals are exchanged between the two.

(Embodiment 2)
A second embodiment of the present invention will be described with reference to FIGS. In this embodiment, in the communication network described in the first embodiment, when the parent device A obtains a communication route to each child device in the communication route construction step, as a communication route from the parent device A to the target child device, When a communication route with a predetermined communication quality or higher (that is, the route cost RC is equal to or lower than a predetermined threshold value) can be searched, the communication route is determined as a communication route to the child device, and all of the devices reaching the search target child device are determined. Before searching for a communication route, the search for the communication route to the child device is terminated. For example, in this embodiment, the route cost threshold is set to 5 for the first hop, 10 for the second hop, and 15 for the third hop. In addition, since it is the same as that of the communication network demonstrated in Embodiment 1 except route search processing, the same code | symbol is attached | subjected to the same component and the description is abbreviate | omitted.

  The route search process by the base unit A will be described based on the flowchart of FIG. By the way, FIG. 13A shows a calculation table TB2 used when the communication processing unit 5a of the parent device A performs route search processing. Whether the communication route is determined in the calculation table TB2 described in the first embodiment or not is determined. A route determination flag indicating is added.

  When the communication processing unit 5a of the parent device A starts the route search process, first, the own device (terminal ID = 100) is determined as a route construction terminal (S10), and the route construction terminal is determined as a search target. As shown in b), the flag Visit of the own device (terminal ID = 100) is set to TRUE (◯), the route determination flag is set to “determined”, and the route determination flags of other terminals are set to “undecided” (S11). ). Then, the communication processing unit 5a of the base unit A designates the start point node as a search target terminal ID (= 100) and the end point node IDs in order of 101, 102, 103,. It is searched whether or not the corresponding link exists in the topology table TB1 (S12). Here, if the links that can communicate with the search target terminal are searched in order from the top of the topology table TB, the search takes a very long time especially when the number of topologies is large. In the topology table TB1 as described in the first embodiment, the terminal IDs of the start point node or end point node are sorted in ascending or descending order. Therefore, the start point node is first searched using a binary search. After that, by searching for the link whose end point node matches from the extracted link, the time required for the search can be considerably shortened.

  If the link can be found in the topology table TB1 in S12, the route cost RC1 of the link is compared with the route cost RC recorded in the calculation table TB2 (S13), and the route cost RC1 discovered this time is calculated. If it is smaller than the route cost RC recorded in the table TB2 (RC> RC1), the terminal ID of the previous hop, the route cost, and the number of hops HOP are written in the calculation table TB2 (S14). On the other hand, in S13, if the route cost RC1 discovered this time is equal to or higher than the route cost RC recorded in the calculation table TB2 (RC ≦ RC1), the communication processing unit 5a does not write the route cost to the calculation table TB2. Returning to S12, the processing is continued. When the route cost is not recorded in the calculation table TB2, the route cost RC1 discovered this time is written in the calculation table TB2. Further, when the writing to the calculation table is completed in S14, the communication processing unit 5a determines whether or not the route cost is equal to or less than a threshold value (S15), and if it is equal to or less than the threshold value, determines the communication route to the slave unit. After setting the route determination flag to “determine” (S16), the process returns to S12 and continues. If the route cost is larger than the threshold value in S15, the communication processing unit 5a keeps the route determination flag “undecided”, returns to S12, and continues the processing.

  Here, when the search target terminal is the parent device (terminal ID = 100), since the link is connected to the terminal (101) and the terminal (102) having the terminal IDs 101 and 102, the communication processing unit 5a The number of hops between both terminals HOP (= 1), the terminal ID of the previous hop, and the route cost [terminal (101) is 3, terminal (102) is 2] are recorded in the operation table TB2 (see FIG. 13B). ) Since the route cost of each terminal is equal to or less than the first hop threshold (= 5), the route determination flag of each terminal (101), (102) is set to “determine” (FIG. 13C). reference).

  When all the communicable links for the search target terminal have been searched, the communication processing unit 5a of the base unit A searches the calculation table TB2 for a terminal having a route determination flag “undecided”. If it exists (S17), it is searched whether there is a terminal whose flag Visit is FALSE (a terminal not marked with ○ in the Visit column) (S18). If it exists, the flag Visit is FALSE. The terminal with the lowest root cost is determined as the search target, and the flag Visit of this terminal is set to TRUE (O) (S19), the process returns to S12, and the above processing is repeated. On the other hand, if there is no terminal whose route determination flag is “undecided” in S17 or there is no terminal whose flag Visit is FALSE, the communication processing unit 5a of the base unit A determines that the route search process has been completed. Then, the information of the calculation table TB2 is reflected in the communication route table (S20).

  Here, when the communication processing unit 5a of the parent device A completes the search for all the links that can communicate with the parent device 100, the route cost among the terminals (101 to 106) in which the flag Visit is FALSE. Since the smallest terminal is the terminal whose terminal ID is 102, the communication processing unit 5a sets the terminal (102) as a search target, and sets the flag Visit of the terminal (102) to TRUE (as shown in FIG. 14A). ○), the start point node is designated as the search target terminal ID (= 102), and the end point node is the terminal ID 103, 104, 105 of the terminal whose “route determination flag” is “undecided”, It is designated in order 106, and it is searched whether or not the corresponding link exists in the topology table TB1 (S12). If the corresponding link can be found in the topology table TB1, the route cost RC1 of the corresponding link found this time (terminal ID 104, 105, 106) is compared with the route cost RC of the terminal recorded in the calculation table TB2. If RC> RC1, the terminal ID of the previous hop (= 102), the route cost RC, and the number of hops HOP (= 2) are overwritten in the calculation table TB2, and then the route cost is set to the second hop threshold (= 10). Compared to the above, since any route cost is equal to or less than the threshold value, the route determination flag is set to “determine” (see FIG. 14B).

  When the detection of all communicable terminals for the terminal (102) is completed, the communication processing unit 5a of the parent device A searches the calculation table TB2 for a terminal having a route determination flag “undecided”. To do. Here, since the route determination flag has not yet been determined for the terminal (103) whose terminal ID is 103, the communication processing unit 5a of the parent device A searches for a terminal whose flag Visit is FALSE, and the flag Visit The terminal having the lowest root cost (the terminal having the terminal ID of 101) is set as the search target among the terminals having the FALSE, and the flag Visit of the terminal (101) is set to TRUE (as shown in FIG. 15A). ○), the start point node is designated as the search target terminal ID (= 101), the end point node is designated as the terminal ID 103 of the terminal whose “route decision flag” is “undecided”, It is searched whether or not the corresponding link exists in the topology table TB1 (S12). If the corresponding link can be found in the topology table TB1, the route cost RC1 of the terminal (103) is compared with the route cost RC of the terminal recorded in the calculation table TB2, and if RC> RC1, the previous calculation table TB2 is displayed. The hop terminal ID, route cost, and hop count HOP (= 2) are overwritten. Here, since the route cost of the terminal (103) has not been determined, the communication processing unit 5a of the parent device A overwrites the terminal ID of the previous hop, the route cost, and the number of hops HOP (= 2) for the terminal (103). After that, the route cost is compared with the threshold value (= 10) for the second hop, and since any route cost is equal to or less than the threshold value, the route decision flag is set to “decide” (see FIG. 15B).

  When all the terminals that can communicate with the terminal (101) have been detected, the route determination flags of all the terminals become “determined”, so that the communication processing unit 5a of the parent device A can set the communication routes of all the terminals. The table search unit 5b is used to reflect the information in the calculation table TB2 in the communication route table of the storage unit 3, and the route search process is terminated (S20). Thereafter, the communication route recorded in the communication route table A communication signal is exchanged between the parent device A and each of the child devices Bn.

  As described above, in the present embodiment, when the communication processing unit 5a of the parent device A performs the route search process, a communication route (from a parent device A to a target child device) having a communication quality equal to or higher than a predetermined communication quality ( In other words, when a communication route having a route cost equal to or less than a predetermined threshold value can be searched, the communication route is determined as a communication route to the child device, and the search process for the communication route to the child device is completed. As a communication route between the parent device A and the child device Bn, a communication route having a predetermined communication quality or higher can be secured, and all communication routes leading to the child device are searched, and communication with the best communication quality is found from among them. A communication route can be searched in a shorter time than when a route is selected.

  In this embodiment, the communication route search process is performed using the topology table TB1 described in the first embodiment, but the route search process as in the present embodiment is performed using the conventional topology table TB1 ′. Even in this case, when a communication route with a predetermined communication quality or higher (that is, a communication route with a route cost equal to or less than a predetermined threshold) can be searched for as a communication route from the parent device A to the target child device, the communication route is determined as the child device. The communication route search time can be shortened by determining the communication route to and terminating the communication route search process for the child device.

  The above-described configuration example is assumed to be used for the PLC network described in the conventional configuration, but uses a wireless transmission path such as a communication network using another wired transmission path, or a wireless LAN using low-power radio. The above-described technique may be applied to various multi-hop communication networks such as a wireless network.

  Furthermore, the PLC network is known to have a low-speed PLC that uses a low frequency band of 10 to 450 kHz and a high-speed PLC that uses a high-frequency band of 2 to 30 MHz. Since the transmission speed is slow, it is particularly effective to be able to grasp the network topology even with low traffic as in the above configuration, and it is only necessary to have an adjacent node table even if each node does not have a link of the entire communication network. The capacity of the memory to be mounted on can be reduced. In addition, compared with the case where other wired transmission lines are used, the network topology and communication quality are easily changed in the PLC depending on the on / off and operating state of the electrical equipment serving as each node, so the technique of the present invention is effective. .

(A) (b) is explanatory drawing of the topology table used for the construction method of the communication route of Embodiment 1, (c) is explanatory drawing of the conventional topology table. (A)-(c) is explanatory drawing of the other topology table used for the same as the above. (A) is a schematic block diagram of a communication network using the same as above, (b) is an explanatory diagram of a topology table. It is a flowchart explaining a route search process same as the above. (A)-(c) is explanatory drawing of the calculation table used for the same as the above. (A) (b) is explanatory drawing of the calculation table used for the same as the above. (A) (b) is explanatory drawing of the calculation table used for the same as the above. (A) (b) is explanatory drawing of the calculation table used for the same as the above. (A) (b) is explanatory drawing of the calculation table used for the same as the above. (A) (b) is explanatory drawing of the calculation table used for the same as the above. (A) (b) is explanatory drawing of the calculation table used for the same as the above. 10 is a flowchart illustrating route search processing according to the second embodiment. (A)-(c) is explanatory drawing of the calculation table used for the same as the above. (A) (b) is explanatory drawing of the calculation table used for the same as the above. (A) (b) is explanatory drawing of the calculation table used for the same as the above. It is a system configuration | structure figure of the communication network using the same as the above. It is a schematic block diagram of the communication terminal using the same as the above. (A)-(d) is explanatory drawing of the packet format used for the same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Communication network 2 Communication terminal 3 Memory | storage part 4 PLC interface part 5 Control part 5a Communication processing part 5b Table processing part 5c H packet transmission timer part A Parent | base station B1-B5 Slave | subunit TB1 Topology table TB2 Calculation table

Claims (7)

One of the plurality of communication terminals constituting the communication network is a master unit and the rest is a slave unit. The master unit stores a desired communication route from the storage unit storing the communication route between the master unit and each slave unit. By reading the communication route to the slave unit and exchanging communication signals between adjacent terminals according to the communication route, the master unit can communicate directly from each slave unit when communicating between the master unit and the slave unit. A communication route construction method for receiving link information related to a neighboring terminal and constructing a communication route to each slave unit based on the received link information,
A link information receiving step for receiving link information related to an adjacent terminal with which the slave can communicate directly from each slave, and the terminal ID of the start-side communication terminal and the communication terminal on the end-point based on the received link information Based on the topology recording step of recording the terminal ID of the terminal and the link cost indicating the communication quality level between both terminals in a topology table composed of a one-dimensional data table, and the link information recorded in the topology table A communication route construction method, comprising: a communication route construction step for obtaining a communication route to each child device using a computer.   When obtaining a communication route to each child device using the Dijkstra algorithm in the communication route construction step, as a communication route from the parent device to the target child device, a communication route with a predetermined communication quality or higher can be searched. The communication route to the child device is determined as the communication route, and the search for the communication route to the child device is terminated before searching for all the communication routes leading to the child device. The construction method of the described communication route.   The communication route construction step is executed in a state in which the topology table is sorted so that the magnitude relationship between the terminal ID of the communication terminal on the start point side and the terminal ID of the communication terminal on the end point side is a constant relationship. The communication route construction method according to claim 1 or 2.   The communication route construction step is executed in a state in which the terminal IDs of the communication terminals on the start side stored in the topology table are sorted in ascending order or descending order. The construction method of the described communication route.   5. The communication route construction method according to claim 4, wherein the communication route construction step is executed in a state where the terminal IDs of the terminal side communication terminals stored in the topology table are sorted in ascending or descending order.   In the topology recording step, record the terminal IDs and link costs of the start and end side communication terminals in the topology table so that at least one of the terminal IDs of the start and end side communication terminals is arranged in ascending or descending order. The communication route construction method according to claim 1, wherein the communication route is constructed. One of the plurality of communication terminals constituting the communication network is a master unit and the rest is a slave unit. The master unit stores a desired communication route from the storage unit storing the communication route between the master unit and each slave unit. A communication terminal on the parent device side that performs communication between the parent device and the child device by reading a communication route to the child device and exchanging communication signals between adjacent terminals according to the communication route,
Link information receiving means for receiving link information related to an adjacent terminal that can directly communicate with the slave unit from each slave unit, and the terminal ID of the start side communication terminal and the end point communication terminal based on the received link information Based on the table processing means for recording the terminal ID and the link cost indicating the communication quality level between both terminals in a topology table composed of a one-dimensional data table, and the link information recorded in the sorted topology table And a communication route construction means for obtaining a communication route to each slave unit using the Dijkstra algorithm.

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