JP2011217122A - Method, device, and program for transferring broadcast packet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the arrival accuracy of packets by suppressing the packets which flow to a wireless network thereby reducing network traffic concerning a packet transfer technology in a wireless network environment.SOLUTION: In an ad-hoc network, in broadcast transfer from a gateway 102 to a communication unit 101, all communication units 101 do not perform the broadcast transfer. A specific communication unit selected from among the communication units 101 with predetermined algorithm is designated as a broadcast object unit. Then, only the selected broadcast object unit performs the broadcast transfer to communication units 101 in the surroundings. When the communication unit 101 which receives the broadcast transfer is a non-broadcast object unit, broadcast transfer is performed no more.

Description

  The present invention relates to a broadcast packet transfer method, apparatus, and program in an ad hoc network environment.

  There is known an ad hoc wireless network in which communication devices are connected wirelessly directly or via another communication device without using a network connection device such as a router, an access point, or a base station.

  In an ad hoc wireless network environment, it is required to update firmware for operating a large number of communication units. As a firmware update method, conventionally, firmware is downloaded to a communication unit by broadcast transfer to update the firmware.

  Also, in broadcast transfer, there is known a prior art that performs packet transfer efficiently by suppressing broadcast by dividing a region based on distance, reception power value, and transmission timing centering on the transmission source. (For example, the technique described in Patent Document 1).

JP 2005-86643 A

  However, in the above-described conventional technology, the traffic of the wireless network increases dramatically because each communication unit performs broadcast transfer and the transfer packet size is large. That is, the amount of information flowing through the wireless network is “communication unit × packet size”. As a result of this increase in traffic, packet reception becomes abnormal, and there are many communication units in which firmware download is not completed normally. There is also a communication unit that is disconnected from the network due to a communication failure, and there is a problem that a person has to go to the communication unit to perform firmware update work.

  FIG. 1 shows a flow of packets between units when all communication units perform broadcast transfer. First, as the first hop, broadcast transfer is performed from the gateway machine 102 that is the transmission source of the firmware to the surrounding communication units 101-1. Next, as each second hop, broadcast transfer is performed from each of the communication units 101-1 that has received the first hop to the surrounding communication units 101-2. Furthermore, as a third hop, broadcast transfer is performed from each of the communication units 101-2 that has received the second hop to the surrounding communication units. In this way, broadcast transfer is performed step by step from the gateway machine 102 to the surrounding communication units 101-1, 101-2,... In the first, second, and third hops. And at each stage (hop), all the communication units 101-1, 101-2, ... performed broadcast transfer. For this reason, it can be seen that the traffic is explosively increasing as indicated by a thin broken line (first hop), a thin solid line (second hop), and a thick broken line (third hop).

  In addition, the above-described conventional technique in which broadcasting is performed by dividing an area based on distance, reception power value, and transmission timing with the transmission source as the center has the following problems. That is, when a large number of packets (equivalent to 5000 packets) such as firmware data need to be transferred to a small number of communication units (for example, several hundred to several thousand units), each unit can communicate with each other. A lot of waiting time is required for position detection and transmission timing determination. Therefore, the method as described above is unsuitable for immediate firmware update. In addition, a communication unit corresponding to several hundred to several thousand units includes / controls a transmission source position detection unit, a reception power value detection unit, a region detection unit, and a transmission timing determination unit. Since this is necessary, the part cost and power consumption may increase. Further, when the communication unit is located at a dense location and broadcast is performed, all the dense communication units broadcast, the wireless network is congested, and packet loss is likely to occur. For this reason, in order to efficiently reach a large number of packets such as firmware data, it is necessary to select an appropriate broadcast execution unit.

  Accordingly, an object of the present invention is to reduce packets that flow through a wireless network, reduce network traffic, and improve packet arrival accuracy.

  In an example of the aspect, in a packet transfer method that is connected to a network including a plurality of communication units and executed by a control device that controls packet transfer in any of the communication units, the control device is stored in a storage unit. Referring to adjacent unit information related to adjacent communication units for each communication unit and route information indicating a route between each communication unit and the control device, received from another communication unit or the control device among the plurality of communication units Selecting a communication unit to which a packet is to be broadcast-transmitted, and generating a packet including information indicating the selected communication unit to be broadcast-transmitted and transmitting the packet to one of the plurality of units. A broadcast transfer method is provided.

  Since the wireless radio wave reachable range is selected from the communication units so as not to overlap, the wireless network traffic can be reduced and broadcasting can be performed more efficiently.

It is a prior art figure which shows the flow of the packet between units when all the communication units implement broadcast transfer. It is explanatory drawing of the basic operation | movement of this embodiment. It is a network block diagram to which this embodiment is applied. It is a block diagram of a gateway. It is a block diagram of a communication unit. It is a block diagram of an ad hoc FPGA. It is a figure which shows the 1st process sequence example (1/4). It is a figure which shows the 1st process sequence example (2/4). It is a figure which shows the 1st process sequence example (3/4). It is a figure which shows the 1st process sequence example (4/4). It is a figure which shows the example of a message format of a broadcast transfer permission instruction | indication. It is a figure which shows the 2nd process sequence example (1/4). It is a figure which shows the 2nd process sequence example (2/4). It is a figure which shows the 2nd process sequence example (3/4). It is a figure which shows the 2nd process sequence example (4/4). It is a figure (initial state) which shows the example of selection of an adjacent unit and path | route information, and a communication unit. (Example 1) which shows the example of selection of an adjacent unit and path | route information, and a communication unit. FIG. 6 is a diagram (Example 1) illustrating a selection unit adjacent to each communication unit. (Example 2) which shows the example of selection of an adjacent unit and path | route information, and a communication unit. (Example 2) which shows the selection unit adjacent to each communication unit. (Example 3) which shows the example of selection of an adjacent unit and path | route information, and a communication unit. (Example 3) which shows the selection unit adjacent to each communication unit. (Example 4) which shows the example of selection of an adjacent unit and path | route information, and a communication unit. (Example 4) which shows the selection unit adjacent to each communication unit. (Example 5) which shows the example of selection of an adjacent unit and path | route information, and a communication unit. (Example 5) which shows the selection unit adjacent to each communication unit. (Example 6) which shows the example of selection of adjacent unit and path | route information, and a communication unit. (Example 6) which shows the selection unit adjacent to each communication unit. It is a figure (final result) which shows the example of selection of adjacent unit and path | route information, and a communication unit. It is a figure (final result) which shows the selection unit adjacent to each communication unit. It is a flowchart which shows the selection process of a selection unit. It is a flowchart which shows the detail of the selection process of a broadcast target unit. It is a figure which shows the traffic state of the wireless network by the packet transfer in this embodiment. It is a block diagram of the hardware system which can implement | achieve the system of this embodiment.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.
FIG. 2 is an explanatory diagram of the basic operation of the present embodiment. A wireless network environment is constructed around a gateway 102, which is a relay device connected to a server (not shown), particularly via a LAN (local area network) or the like, and each communication unit (communication device) 101 is connected to an ad hoc network. Configure the network. In FIG. 2, the communication unit 101 that performs first-hop communication with the gateway 102 is located inside a circle centered on the gateway 102. Those located outside the circle communicate with the second hop.

  In this embodiment, in the broadcast transfer from the gateway 102 to the communication unit 101, not all the communication units 101 perform the broadcast transfer. A specific communication unit selected from among the communication units 101 is designated as a broadcast target unit from the gateway 102 via the server described later by the following algorithm. In FIG. 2, the broadcast target unit is indicated by a black solid mark, and a white solid line by a horizontal line mark. Then, only the selected broadcast target unit performs broadcast transfer to surrounding communication units 101. If the communication unit 101 that has received the broadcast transfer is a non-broadcast target unit, no further broadcast transfer is performed.

A more specific operation of this embodiment will be described below.
Step 1.
Each communication unit 101 periodically sends a Hello packet to an adjacent communication unit (hereinafter referred to as “adjacent unit”). The communication unit 101 that has received the Hello packet stores identification information (hereinafter referred to as “adjacent unit information”) of the communication unit indicating the transmission source of the Hello packet added to the Hello packet. Each communication unit 101 notifies the server (not shown in FIG. 2) of adjacent unit information via the gateway 102 at regular intervals (one hour interval or the like). The server manages the notified adjacent unit information for each communication unit 101.

Step 2.
When a packet is transferred from the communication unit 101 to the server, route information is also notified at the same time. The server manages path information for each communication unit 101. That is, the route information for one communication unit 101 is information indicating the route of another communication unit 101 through which a packet is transferred from the server to the communication unit 101 via the gateway 102. When a packet is transferred, every time it passes through a communication unit 101 in the middle, identification information of the communication unit 101 that passes through is added to the route information.

Step 3.
Based on the adjacent unit information and path information managed by the server, the broadcast target unit to be broadcast is received by all the communication units 101 according to the following algorithms (a) to (d). Select repeatedly.
(A) A broadcast target unit is selected so that the communication unit 101 having the smallest number of adjacent units can reliably perform broadcast transfer. Hereinafter, the communication unit 101 selected as the broadcast target unit is referred to as a selection unit. However, the selection unit is a communication unit that is not adjacent to the gateway 102. This is because, for the communication unit 101 adjacent to the gateway 102, the packet is directly transferred from the gateway 102 and no relay is required.
(B) The communication unit 101 that minimizes the number of hops from the gateway 102 is selected. That is, based on the route information, the communication unit 101 that becomes the shortest route (shortest route) is selected. The shortest route is selected in order to suppress wireless network congestion due to packet transfer.
(C) The selected unit is determined so as to have more adjacent units that cannot be covered by other selected units. That is, the unit having the largest number of adjacent units excluding the selected unit and the adjacent units that it covers is selected as the selected unit.
(D) The upper limit (= N) of the number of selected units that overlap is determined in advance. That is, let N be the upper limit number of selected units included in adjacent units of each communication unit 101. Then, when an attempt is made to select a certain communication unit 101, if the selected unit exceeds the upper limit number N in the communication unit 101 included as an adjacent unit, the selected unit is not selected. Then, among the adjacent units of the non-broadcast target unit, the communication unit 101 having a small number of adjacent units in which the overlap of the broadcast target units exceeds N is selected as the broadcast target unit. This is to suppress congestion of the wireless network.

Step 4.
The server performs step 3. A broadcast transfer permission instruction is notified by unicast to the broadcast target unit (selected unit) selected in.

Step 5.
The server performs step 3. The firmware program data is transferred to the broadcast target unit selected in step 1 by unicast or broadcast. If a broadcast is to be performed, step 4. The non-broadcast target unit that is not permitted in (1) does not perform broadcast transfer, and only the permitted broadcast target unit performs broadcast transfer. When unicast is performed, the broadcast target unit does not yet perform broadcast transfer and waits for a permission instruction from the server.

Step 6.
When the server transmits the firmware program data by unicast, the server notifies the broadcast target unit of a broadcast start instruction, and the broadcast target unit that receives the start instruction broadcast-transfers the firmware program data to the adjacent communication unit 101. To do.

A specific configuration based on the basic operation of the above-described embodiment will be described below.
FIG. 3 is a network configuration diagram to which the present embodiment is applied. In FIG. 3, the same parts as those in FIG. Similarly to the case of FIG. 2, the broadcast target unit is indicated by a black solid mark and a white solid by a horizontal line mark.

  The server 301 is connected to a gateway 102 that is a relay device via a LAN (local area network) or the like. The gateway 102 relays communication information for the server 301 with each communication unit 101 via a wireless network. The gateway 102 and each communication unit 101 constitute an ad hoc network.

  FIG. 4 is a configuration diagram of the gateway 102 of FIG. Communication with the server 301 via a LAN or the like is terminated by an L2SW (layer 2 switch) 401. Communication with the communication unit 101 by wireless communication is terminated by a plurality of communication units 403 each having a communication port, and transmission / reception frame encoding or decoding processing is executed. The communication unit 403 is configured by, for example, PHY (PHYsical Layer Device). Frame data transmitted / received via the L2SW 401 or the communication unit 101 is processed by an ad hoc FPGA (Field Programmable Gate Array) 402. Here, a process of routing the frame data based on the routing table, a process of communicating upper layer information in the frame data with the CPU 404, and the like are executed. The CPU 404 is a processor that controls the overall processing of the gateway 102, and performs basic operations based on firmware 405 stored in a flash memory (not shown). Further, upper layer processing is executed by the middleware 406 stored in the flash memory or the disk storage device.

  FIG. 5 is a configuration diagram of the communication unit 101 of FIG. The configuration of the communication unit 101 is the same as the configuration of the gateway 102 in FIG. 4 except that the function of the L2SW 401 for terminating the LAN is not provided. In FIG. 5, the same ad hoc FPGA 402 and communication unit 403 can be used as in the case of the gateway 102 in FIG. The CPU 501 is a processor that controls the overall processing of the communication unit 101, and performs basic operations based on firmware 502 stored in a flash memory (not shown). Further, upper layer processing is executed by the middleware 503 stored in the flash memory or the disk storage device. In this embodiment, the firmware 502 is updated based on firmware program data transferred from the server 301 via the gateway 102.

  FIG. 6 is a configuration diagram of the ad hoc FPGA 402 of FIG. 4 or FIG. The data analysis / control unit 601 analyzes the frame data transmitted and received by the data reception unit 602 and the data transmission unit 603 with respect to the L2SW 401 in FIG. 4 and the communication unit 403 in FIG. 4 or FIG. It is a field programmable gate array that controls the above.

  A first processing sequence example of the broadcast transfer of the present embodiment executed between the server 301, the gateway 102, and the communication unit 101 with the configuration of the above-described embodiment will be described with reference to the sequence diagrams of FIGS. .

First, in FIG. 3, only one gateway 102 is shown, but a plurality of gateways 102 can be connected under the server 301, and communication is connected via an ad hoc wireless network under each gateway 102. Unit 101 is arranged. The installation position of each communication unit 101 is fixed, and the server 301 manages the position information. Of course, the installation position can be changed.
Sequence S1 (FIG. 7)

The server 301 selects some communication units 101 as broadcast target units. Details of the method for selecting the communication unit 101 will be described later. Here, as an example, it is assumed that the communication unit 101 described as communication unit 1, communication unit 3, and communication unit 4 in FIG. 3 is selected by the server 301 as a broadcast target unit. Thereby, the communication unit 101 described as the communication unit 2 and the communication unit 5 in FIG. 3 becomes a non-broadcast target unit. Of course, this is only an example, and other configuration examples may be used. In the following description, the communication units 1 to 5 will be described.
Sequence S2 to S6 (FIG. 7)
A broadcast transfer permission instruction is notified from the server 301 to the communication units 1, 3, and 4 in FIG. 3 via the gateway 102 (S2 and S3 in FIG. 7).

  Thereafter, the communication units 1, 3, and 4 in FIG. 3 perform broadcast transfer as broadcast target units, and the communication units 2 and 5 in FIG. 3 do not perform broadcast transfer as non-broadcast target units (FIG. 3). 7 S4).

  The communication units 1, 3, and 4 that have received the transfer permission instruction by the broadcast transfer permission instruction return a broadcast transfer permission instruction response to the server 301 via the gateway 102 (S5 and S6 in FIG. 7).

Sequence S7 (FIG. 7)
The server 301 distributes the firmware program data to be updated to the gateway 102 using FTP (File Transfer Protocol).

Sequence S8 (FIG. 7)
The server 301 transmits a communication unit firmware update start instruction to the gateway 102.

Sequences S9 and S10 (FIGS. 7 and 8)
The gateway 102 converts the firmware program data transferred by FTP into an ad hoc communication format (S9 in FIG. 7). Then, the gateway 102 broadcast-transfers the converted firmware program data to each of the communication units 1 to 5 (S10 in FIG. 8).

Sequence S11, S12 (FIG. 8)
Each communication unit 101 receives the firmware program data transferred by broadcast and stores it in the internal flash memory (see 502 in FIG. 5) (S11 in FIG. 8).

  Here, the communication units 1, 3, and 4 that have received the broadcast transfer permission instruction in the sequence S3 in FIG. 7 broadcast-transfer the received firmware program data (S12 in FIG. 8). The communication unit 4 receives the farm program data at the second hop via the communication unit 1 and broadcast-transfers it (S10 ′ in FIG. 8). Further, in the example of FIG. 8, the communication unit 5 is also transferred the farm program data in the second hop via the communication unit 1, but an example in which reception has failed is shown (S10 in FIG. 8). -3)

Sequence S13, S14 (FIG. 9)
The gateway 102 broadcast-transfers the firmware program data reception result inquiry request to each of the communication units 1 to 5. Only the communication units 1, 3, and 4 that have received the broadcast transfer permission instruction in the sequence S3 in FIG. 7 broadcast transfer the received inquiry request (S14 in FIG. 9). The communication units 4 and 5 receive the inquiry request at the second hop via the communication unit 1.

Sequence S15 etc. (FIG. 9)
The communication unit that has received the firmware program data reception result inquiry request determines the reception state of the firmware program data, and does nothing if the reception is completed normally. If the reception state is abnormal, a firmware program data reception abnormality notification is returned to the GW (for example, S15 in FIG. 9).

Sequence S16 (FIG. 10)
When the gateway 102 receives the firmware program data reception abnormality notification (S15 in FIG. 9, etc.), the gateway 102 transmits the firmware program data by unicast to the communication unit (for example, the communication unit 5) in which the reception abnormality has occurred.

Sequence S17 (FIG. 10)
The gateway 102 transmits the firmware program data reception result inquiry request to the target communication unit 5 by unicast.

Sequence S18 (FIG. 10)
The communication unit 5 that has received the firmware program data reception result inquiry request determines the reception state of the firmware program data. If the reception is completed normally, the communication unit 5 notifies the firmware program data reception completion notification. A program data reception abnormality notification is returned to the gateway 102.

  When an abnormality is notified in S18 for the sequence S17, the sequence S16 to S18 is repeated several times.

Sequence S19 (FIG. 10)
Each of the communication units 1 to 5 autonomously restarts with the new firmware program data after a predetermined time from receiving the new firmware program data.

Sequence S20 (FIG. 10)
The gateway 102 broadcast-transfers the firmware program version inquiry request to the communication units 1 to 5. The communication units 4 and 5 receive the inquiry request at the second hop via the communication unit 1.

Sequence S21 (FIG. 10)
Upon receiving the firmware program version inquiry request, each of the communication units 1 to 5 notifies the gateway 102 of the version of the firmware program data being executed by itself.

Sequence S22 (FIG. 10)
As a result of receiving the firmware program version notification from each of the communication units 1 to 5, the gateway 102 unicasts the firmware program data again in sequence S <b> 16 to S <b> 18 when there is a communication unit 101 with an older version.

Sequence S23, S24 (FIG. 10)
After completing the upgrade of the firmware program data for all the communication units 101, the gateway 102 transmits a firmware update completion notification to the server 301 (S23 in FIG. 10). In response to this, a firmware update completion response is returned from the server 301 to the gateway 102 (S24 in FIG. 10), and the firmware update process is completed.

  FIG. 11 shows the data structure of the message format of the broadcast transfer permission instruction shown in S2 and S3 of FIG. The unit ID is an individual ID (identification data) for each communication unit 101. Also, the broadcast transfer permission instruction instructs transfer prohibition with a value of 0, and instructs transfer permission with a value of 1. Now, a broadcast transfer permission instruction having a value of 1 is notified to the communication units 1, 3, and 4 selected in the sequence S1.

  Next, a second processing sequence example of broadcast transfer according to this embodiment will be described with reference to the sequence diagrams of FIGS. In FIG. 12 to FIG. 15, the same processing sequence as the first processing sequence example in FIG. 7 to FIG. The processing sequences in FIGS. 12, 14, and 15 are the same as those in FIGS. 7, 9, and 10, respectively.

  In FIG. 8 in the first processing sequence example, transmission of firmware program data from the gateway 102 to each communication unit 101 is performed by broadcast transfer (S10 in FIG. 8). Then, the communication units 1, 3, and 4 that received the broadcast transfer permission instruction in the sequence S3 in FIG. 7 autonomously broadcast-transferred the firmware program data received by the broadcast transfer (S12 in FIG. 8).

  On the other hand, in FIG. 13 in the second processing sequence example, the transmission of the firmware program data from the gateway 102 to each communication unit 101 is executed by individual unicast transmission (S25 in FIG. 13). The communication units 1, 3, and 4 that have received the broadcast transfer permission instruction in the sequence S3 of FIG. 12 further wait for a broadcast start instruction by unicast transmission from the gateway 102, and then broadcast transfer the received firmware program data. (S26 → S12 in FIG. 13). Thereby, reliable transmission of the firmware program data to the broadcast target unit is realized.

  Next, step 1. And step 2. Step 3. A specific example of the process of selecting a broadcast target unit using the algorithms (a) to (d) will be described with reference to FIGS. 16 to 30.

  Step 1. 3, the server 301 in FIG. 3 determines the adjacent unit information and the path information for each communication unit 101 and the gateway 102 based on the notification from each communication unit 101 in FIG. 3 including the gateway 102 in FIG. Manage. FIG. 16A is a table showing an example of adjacent unit / route information managed by the server 301. The information shown in this table is created based on adjacent unit information and path information with which the server 301 communicates with each communication unit 101 or GW 102. The left end of each row indicates the gateway 102 (“GW” in the figure) or the communication unit 101 (“unit” in the figure) to be managed. A number or GW (indicating the gateway 102) in each row except the left end indicates the number of the communication unit 101 or gateway 102 adjacent to the communication unit 101 or gateway 102 at the left end. For example, it is stored that the adjacent unit of the communication unit 101 with the number 1 is the gateway 102 (GW) and the communication unit 101 with the numbers 2, 14, 21, 23, 24, 25, 27, 30, 34, and 35. Has been. Further, the path between the communication units 101 can be determined by following each adjacent unit number.

  FIG. 16B is a diagram showing the positional relationship between the gateway 102 (“GW” in the figure) and each communication unit 101 (numbers in the figure). An example in which the gateway 102 is arranged in the center and the number of communication units 101 is 40 is shown.

  In the example of FIG. An example of processing for selecting a broadcast target unit by the selection algorithm (a) to (d) will be described below.

<Example 1>
First, the communication unit 101 having the smallest number of adjacent units is picked up. Step 3. As a result of referring to the adjacent unit / path information in FIG. 16A, the communication unit 101 having the smallest number of adjacent units is determined to be the 11th unit.

Next, the adjacent units are sequentially traced until the path can be established from the 11th unit having the fewest adjacent units and not including the selected unit toward the GW 102.
First, the 11th adjacent unit is the 13th and 15th unit from FIG. There are two adjacent units of No. 13 and three adjacent units of No. 15. Here, step 3. The adjacent unit on the shortest route is selected by (b). The route to the 11th unit is as follows from the adjacent unit / route information in FIG.

No. 1 GW → 26 → 15 → 11
No. 2 GW → 26 → 15 → 13 → 11
No. 3 GW → 34 → 26 → 15 → 11

Etc. GW indicates the gateway 102, and each number indicates an identification number of each communication unit 101. Here, the shortest route is No. Since there is only one of the units, unit 15 is selected as the selection unit. If there are a plurality of shortest routes, step 3. The shortest route is selected according to (b).

Next, for the newly selected 15th selected unit, step 3. The adjacent unit on the shortest route is selected by (b). There are three adjacent units of the 15th unit, 11th, 13th and 26th. The route to the 15th unit is as follows from the adjacent unit / route information in FIG.

No. 1 GW → 26 → 15
No. 2 GW → 23 → 26 → 15
No. 3 GW → 34 → 26 → 15

Etc., but the shortest route is No. Since there is only one of the units, the unit 26 is selected as the selection unit. If there are a plurality of shortest routes, step 3. The shortest route is selected according to (b).

  The 26th unit is an adjacent unit of the GW 102. Since the path from the 11th unit having the fewest adjacent units to the GW 102 can be established, the processing for the 11th unit is terminated.

  By the selection process of the first embodiment executed by the server 301, the 15th and 26th units are selected as broadcast target units. As a result, the broadcast packet is transferred to the 11th unit through the route of GW → 26 → 15 → 11.

  Further, in the positional relationship between the GW 102 and each communication unit 101 shown in FIG. 16B, the units covered by the 15th and 26th selection units selected in the selection process of the first embodiment are shown in FIG. The unit falls within the range indicated by the two dashed circles b). Here, the unit covered by the selected unit indicates a unit in a range that is further broadcast-transferred from the unit selected as the broadcast target unit.

  By the selection process of the first embodiment, the adjacent unit / route information in FIG. 16A is as shown in FIG. In FIG. 17 (a), the unit having the smallest number of adjacent units (solid square in the figure) with respect to the leftmost unit number and the adjacent unit number corresponding thereto, the unit selected by the selection algorithm (double solid line in the figure) ) And the units covered by the selection unit (broken squares in the figure) are given individual mark information.

  Furthermore, when the selection process according to the first embodiment is completed, as shown in FIG. 18, the information on the selected units adjacent to each communication unit 101 is managed. Also in FIG. 18, for each unit number at the left end, the unit with the smallest number of adjacent units (solid square in the figure), the unit selected by the selection algorithm (double solid square in the figure), and the selected unit Individual mark information similar to that in the case of FIG. 17A is assigned to the units to be covered (dotted squares in the figure).

<Example 2>
Following the selection process of the first embodiment, the following selection process of the second embodiment is further executed. Here, it considers excluding the adjacent unit of the unit selected previously.

  First, the communication unit 101 having the smallest number of adjacent units is picked up. Step 3. As a result of referring to the adjacent unit / route information in FIG. 17A, the communication unit 101 having the smallest number of adjacent units is determined to be the seventh unit.

Next, the adjacent units are sequentially traced until the path can be established from the 7th unit having the fewest adjacent units and including no selected unit toward the GW 102.
First, the adjacent unit No. 7 is three units No. 6, No. 14, and No. 25 from FIG. Here, step 3. The adjacent unit on the shortest route is selected by (b). The route to the 7th unit is as follows from the adjacent unit / route information in FIG.

No. 1 GW → 1 → 25 → 7
No. 2 GW → 1 → 14 → 7
No. 3 GW → 34 → 1 → 25 → 7
No. 4 GW → 1 → 25 → 14 → 7

Etc., but the shortest route is No. 1 and No. Two routes of 2.

  If there are multiple shortest routes, step 3. Apply (c). Units adjacent to the unit 7 in the two routes are the numbers 14 and 25. Of these, seven of the 25th units have the largest number of adjacent units excluding the selected unit and the adjacent units that it covers.

Here, step 3. (D) is applied. By checking the selected unit information adjacent to each communication unit 101 in FIG. 18, when the 25th new selected unit is added, the number of selected units in the adjacent unit is N (for example, 4). It is determined whether there are more units. The 25th adjacent unit is the 1st, 2nd, 6th, 14th, 27th, 30th unit based on the adjacent unit / route information in FIG. In FIG. 18, even if unit 25 is newly added as an adjacent unit to these units, nothing exceeding N = 4 appears.
From the above, the 25th unit is selected as the selection unit.

Then, for the newly selected 25th selected unit, step 3. The adjacent unit on the shortest route is selected by (b). The route to the 25th unit is based on the adjacent unit / route information in FIG.

No. 1 GW → 1 → 25
No. 2 GW → 24 → 1 → 25
No. 3 GW → 34 → 1 → 25

Etc., but the shortest route is No. Since there is only one, the first unit is selected as the selection unit.

  The first unit is an adjacent unit of the GW 102. Since the route from the seventh unit that has the fewest adjacent units and does not include the selected unit to the GW 102 has been established, the processing for the seventh unit is terminated.

  The first and 25th units are selected as broadcast target units by the selection process of the second embodiment executed by the server 301. As a result, the broadcast packet is transferred to the seventh unit through the route of GW → 1 → 25 → 7.

  Further, the units covered by the selection units No. 1 and No. 25 selected in the selection process of the second embodiment are units that fall within the range indicated by the two broken circles in FIG. The solid circle is a range covered by the selection unit selected by the selection process of the first embodiment.

  By the selection process of the second embodiment, the adjacent unit / route information in FIG. 17A is updated as shown in FIG. In FIG. 19A, with respect to the leftmost unit number and the adjacent unit number corresponding thereto, as in FIG. 17A, the unit having the smallest adjacent unit, the unit selected by the selection algorithm, and Individual mark information is assigned to each unit covered by the selected unit. Further, in FIG. 19 (a), marks are also given to adjacent units (indicated by a hatched square in the drawing) of the selected unit previously selected (here, in the first embodiment).

  Furthermore, the selection unit information adjacent to each communication unit 101, which is managed when the selection process according to the second embodiment is completed, is updated as shown in FIGS. Also in FIG. 18, for each unit number at the left end, the unit with the smallest number of adjacent units (solid square in the figure), the unit selected by the selection algorithm (double solid square in the figure), and the selected unit Individual mark information similar to that in the case of FIG. 17A is assigned to the units to be covered (dotted squares in the figure). Further, in FIG. 20, marks are also given to the adjacent units (indicated by the hatched squares in the figure) of the selected unit previously selected (here, in the first embodiment).

<Example 3>
Following the selection process of the second embodiment described above, the following selection process of the third embodiment is further executed. Here, it considers excluding the adjacent unit of the unit selected previously.

  First, the communication unit 101 having the smallest number of adjacent units is picked up. Step 3. As a result of referring to the adjacent unit / path information in FIG. 19A, the communication unit 101 having the smallest number of adjacent units is determined to be the 20th unit.

Next, the adjacent units are sequentially traced until the route can be established from the 20th unit having the fewest adjacent units and including no selected unit toward the GW 102.
The adjacent unit of No. 20 is three units of No. 5, 10, and 18 from FIG. Here, step 3. The adjacent unit on the shortest route is selected by (b). The route to the unit No. 20 is based on the adjacent unit / route information in FIG.

No. 1 GW → 8 → 5 → 20
No. 2 GW → 9 → 5 → 20
No. 3 GW → 8 → 10 → 20
No. 4 GW → 9 → 18 → 20

The adjacent units that pass through the shortest route are three units of Nos. 5, 10, and 18.

If there are a plurality of shortest routes, step 3. Apply (c). In the above three units, the number of adjacent units excluding the selected unit and the adjacent units that it covers is shown in FIG.

Unit 5: 8 Unit 10: 4 Unit 18: 5

It becomes. Therefore, the unit with the largest number of adjacent units excluding the selected unit and the adjacent units that it covers is the unit No. 5.

Here, step 3. (D) is applied. By checking the selected unit information adjacent to each communication unit 101 in FIG. 20, when the fifth new selected unit is added, the number of selected units in the adjacent unit is N (for example, 4). It is determined whether there are more units. The 5th adjacent unit is the 8th, 9th, 10th, 16th, 19th, 20th, 31st, and 36th units based on the adjacent unit / route information in FIG. In FIG. 20, even if the unit No. 5 is newly added to these units as an adjacent unit, those exceeding N = 4 do not appear.
From the above, the fifth unit is selected as the selection unit.

Then, for the newly selected No. 5 selection unit, step 3. The adjacent unit on the shortest route is selected by (b). The route to the 5th unit is as follows from the adjacent unit / route information in FIG.

No. 1 GW → 8 → 5
No. 2 GW → 9 → 5
No. 3 GW → 33 → 9 → 5
No. 4 GW → 33 → 8 → 5

However, the adjacent units passing through the shortest route are two units of Nos. 8 and 9.

If there are multiple shortest routes, step 3. Apply (c). In the above two units, the number of adjacent units excluding the selected unit and the adjacent units that it covers is respectively

Unit 8: 10 units Unit 9: 7 units

It becomes. Therefore, the unit with the largest number of adjacent units excluding the selected unit and the adjacent units that it covers is the 8th unit.

  Here, step 3. (D) is applied. When the information on the selected unit adjacent to each communication unit 101 in FIG. 20 is added to the information on the above-mentioned No. 5 unit is checked, when the No. 8 new selected unit is added, It is determined whether or not there is a unit in which the number of selected units exceeds N (for example, 4). The adjacent unit No. 8 is the unit No. 3, 5, 9, 10, 12, 16, 19, 28, 31, 33, 36 from the adjacent unit / route information in FIG. Even if unit 8 is newly added as an adjacent unit to these units, nothing exceeding N = 4 appears.

From the above, the 8th unit is selected as the selection unit.
The unit No. 8 is an adjacent unit of the GW 102, and since the route from the unit No. 20 that has the fewest adjacent units and does not include the selected unit to the GW 102 has been established, the process for the unit No. 20 ends.

  According to the selection process of the third embodiment executed by the server 301, the fifth and eighth units are selected as broadcast target units. As a result, the broadcast packet is transferred to the 20th unit through the route of GW → 8 → 5 → 20.

  Further, the units covered by the selection units No. 5 and No. 8 selected in the selection process of the third embodiment are units that fall within the range indicated by the two broken circles in FIG. The solid circle is a range covered by the selection unit selected by the selection process up to the second embodiment.

By the selection process of the third embodiment, the adjacent unit / route information in FIG. 19A is updated as shown in FIG.
Furthermore, the selection unit information adjacent to each communication unit 101, which is managed when the selection process of the third embodiment is completed, is updated as shown in FIGS.

  In FIG. 21A and FIG. 22, the meaning of each given mark is the same as in the case of FIG. 19A and FIG.

<Example 4>
Following the selection process of the third embodiment described above, the following selection process of the fourth embodiment is further executed. Here, it considers excluding the adjacent unit of the unit selected previously.

  First, the communication unit 101 having the smallest number of adjacent units is picked up. Step 3. As a result of referring to the adjacent unit / route information in FIG. 21A, the communication unit 101 having the smallest number of adjacent units is determined to be the 22nd unit.

Next, the adjacent units are sequentially traced until the path can be established from the unit 22 having the fewest adjacent units and not including the selected unit toward the GW 102.
The adjacent unit No. 22 is three units No. 17, 38, and 40 from FIG. Here, step 3. The adjacent unit on the shortest route is selected by (b). The route to the 22nd unit is based on the adjacent unit / route information in FIG.

No. 1 GW → 17 → 22
No. 2 GW → 17 → 38 → 22
No. 3 GW → 21 → 17 → 22

Etc., but the unit adjacent to the shortest route is only the unit No. 17.

  Here, step 3. (D) is applied. When the selection unit information adjacent to each communication unit 101 in FIG. 22 is checked, when the 17th new selection unit is added, the number of selection units in the adjacent unit is N (for example, 4). It is determined whether there are more units. The adjacent unit No. 17 is the unit No. 3, 12, 16, 19, 21, 22, 24, 28, 32, 34, 37, 38, 40 based on the adjacent unit / route information in FIG. . In FIG. 22, even if unit 17 is newly added as an adjacent unit to these units, nothing exceeding N = 4 appears.

From the above, the 17th unit is selected as the selection unit.
The unit No. 17 is an adjacent unit of the GW 102, and since the path from the unit 22 having the fewest adjacent units to the GW 102 can be established, the processing for the unit 22 is terminated.

  According to the selection process of the fourth embodiment executed by the server 301, the 17th unit is selected as the broadcast target unit. As a result, the broadcast packet is transferred to the 22nd unit through the route of GW → 17 → 22.

  Further, the unit covered by the 17th selection unit selected in the selection process of the fourth embodiment is a unit that falls within the range indicated by one broken circle in FIG. The solid circle is a range covered by the selection unit selected by the selection process up to the third embodiment.

By the selection process according to the fourth embodiment, the adjacent unit / route information in FIG. 21A is updated as shown in FIG.
Furthermore, the selection unit information adjacent to each communication unit 101, which is managed when the selection process of the fourth embodiment is completed, is updated as shown in FIGS.

  In FIG. 23A and FIG. 24, the meaning of each given mark is the same as in the case of FIG. 21A and FIG.

<Example 5>
Following the selection process of the fourth embodiment described above, the following selection process of the fifth embodiment is further executed. Here, it considers excluding the adjacent unit of the unit selected previously.

  First, the communication unit 101 having the smallest number of adjacent units is picked up. Step 3. As a result of referring to the adjacent unit / path information in FIG. 23A, the communication unit 101 having the smallest number of adjacent units is determined to be the 39th unit.

Next, the adjacent units are sequentially traced until the path can be established from the 39th unit having the fewest adjacent units and including no selected unit toward the GW 102.
The No. 39 adjacent unit is four units No. 9, 18, 31, and 33 from FIG. Here, step 3. The adjacent unit on the shortest route is selected by (b). The route to unit No. 39 is based on the adjacent unit / route information in FIG.

No. 1 GW → 9 → 39
No. 2 GW → 33 → 39
No. 3 GW → 33 → 31 → 39

However, the adjacent units passing through the shortest route are two units of No. 9 and No. 33.

  If there are a plurality of shortest routes, step 3. Apply (c). Of the 9th and 33rd units, the numbers of adjacent units that are not adjacent to the selected unit are 2 (18th and 39th) and 1 (39th), respectively. Therefore, the unit 9 has a large number of adjacent units that are not adjacent to the selected unit.

  Here, step 3. (D) is applied. By checking the selected unit information adjacent to each communication unit 101 in FIG. 24, when the 9th new selected unit is added, the number of selected units in the adjacent unit is N (for example, 4). It is determined whether there are more units. The 9th adjacent unit is the 5th, 8th, 16th, 18th, 19th, 31st, 33th, and 39th units based on the adjacent unit / route information in FIG. In FIG. 24, even if unit 9 is newly added as an adjacent unit to these units, nothing exceeding N = 4 appears.

From the above, the 9th unit is selected as the selection unit.
The 9th unit is an adjacent unit of the GW 102. Since the path from the 39th unit that has the fewest adjacent units and does not include the selected unit to the GW 102 has been established, the process for the 39th unit is terminated.

  According to the selection process of the fifth embodiment executed by the server 301, the ninth unit is selected as the broadcast target unit. As a result, the broadcast packet is transferred to the 39th unit through the route of GW → 9 → 39.

  In addition, the unit covered by the ninth selection unit selected in the selection process of the fifth embodiment is a unit that falls within the range indicated by one broken circle in FIG. The solid circle is a range covered by the selection unit selected by the selection process up to the fourth embodiment.

By the selection process of the fifth embodiment, the adjacent unit / path information in FIG. 23A is updated as shown in FIG.
Furthermore, the selection unit information adjacent to each communication unit 101 managed when the selection process of the fifth embodiment is completed is updated as shown in FIGS.

  In FIG. 25 (a) and FIG. 26, the meaning of each given mark is the same as in the case of FIG. 23 (a), FIG.

<Example 6>
Subsequent to the selection process of the fifth embodiment described above, the following selection process of the sixth embodiment is further executed. Here, it considers excluding the adjacent unit of the unit selected previously.

  First, the communication unit 101 having the smallest number of adjacent units is picked up. Step 3. As a result of referring to the adjacent unit / path information in FIG. 25A, the communication unit 101 having the smallest number of adjacent units is determined to be the 29th unit.

Next, the adjacent units are sequentially traced until the route can be established from the unit No. 29 having the smallest number of adjacent units and not including the selected unit toward the GW 102.
The No. 29 adjacent unit is five units No. 4, 32, 37, 38, and 40 from FIG. Here, step 3. The adjacent unit on the shortest route is selected by (b). The route to the unit No. 29 is based on the adjacent unit / route information in FIG.

No. 1 GW → 17 → 40 → 29
No. 2 GW → 17 → 37 → 29
No. 3 GW → 3 → 37 → 29
No. 4 GW → 3 → 40 → 29
No. 5 GW → 17 → 38 → 29
No. 6 GW → 17 → 32 → 29
The adjacent units passing through the shortest route are 4 units of 32, 37, 38, and 40.

If there are a plurality of shortest routes, step 3. Apply (c). Among the four adjacent units described above, the adjacent unit that is not adjacent to the selected unit is No. 4, and the unit of No. 4 is the three units No. 32, 37, and No. 40. . And the number of each adjacent unit of these units,

The number of adjacent units of No. 32 is 11.
The number of adjacent units of No. 37 is eight.
The number of adjacent units of No. 40 is nine.

Thus, the number 32 unit has the largest number of adjacent units.

  Here, step 3. (D) is applied. When the selection unit information adjacent to each communication unit 101 in FIG. 26 is checked, when the 32nd new selection unit is added, the number of selection units in the adjacent unit is N (for example, 4). It is determined whether there are more units. The adjacent unit No. 32 is the unit No. 3, 4, 12, 16, 17, 19, 28, 29, 37, 38, 40 based on the adjacent unit / route information of FIG. In FIG. 26, when the unit No. 32 is newly added as an adjacent unit to these units, the units No. 16 and No. 19 appear as N = 4. Accordingly, the 32nd unit is not selected as the selection unit.

Next, for the 40th unit having the second largest number of adjacent units, step 3. (D) is applied. By checking the selection unit information adjacent to each communication unit 101 in FIG. 26, when the number 40 new selection unit is added, the number of selection units in the adjacent unit is N (for example, 4). It is determined whether there are more units. The 40th adjacent unit is the 3rd, 4th, 17th, 22nd, 28th, 29th, 32nd, 37th, and 38th units based on the adjacent unit / path information in FIG. In FIG. 26, even if unit 40 is newly added as an adjacent unit to these units, those exceeding N = 4 do not appear.
From the above, the 40th unit is selected as the selection unit.

Subsequently, for the newly selected 40th selected unit, step 3. The adjacent unit on the shortest route is selected by (b). From the adjacent unit / route information in FIG. 25A, the adjacent unit located on the shortest route among the routes to the unit No. 40 is

No. 1 GW → 17 → 40
No. 2 GW → 3 → 40

Therefore, it becomes 2 units of 17th and 3rd. Further, from the selected unit information adjacent to each communication unit 101 in FIG. 26, the route of unit 17 can be established according to the fourth embodiment. For this reason, since the path from the 29th unit that has the fewest adjacent units and does not include the selected unit to the GW 102 has been established, the process for the 29th unit is terminated.

  According to the selection process of the third embodiment executed by the server 301, the 40th unit is selected as the broadcast target unit. As a result, the broadcast packet is transferred along the route of GW → 17 → 40 → 29 together with the 17th unit described in the fourth embodiment.

  Further, the unit covered by the selection unit No. 40 selected in the selection process of the sixth embodiment is a unit that falls within the range indicated by one broken circle in FIG. The solid circle is a range covered by the selection unit selected by the selection process up to the fifth embodiment.

By the selection process of the sixth embodiment, the adjacent unit / path information in FIG. 25A is updated as shown in FIG.
Furthermore, the selection unit information adjacent to each communication unit 101, which is managed when the selection process of the sixth embodiment is completed, is updated as shown in FIGS.

  In FIG. 27A and FIG. 28, the meaning of each mark to be added is the same as in the case of FIG.

<Final result>
As a result of the selection processing of the first to sixth embodiments described above, for all the units shown in FIG. 16, the selected unit is always included in the adjacent units of each unit. This completes the selection unit selection process.

  The selection unit finally selected is 1, 5, 8, 9, 15, 17, 25 from the adjacent unit / route information of FIG. 29A obtained as a final result by updating FIG. , 26, and 40 units. Non-selected units are all units other than the nine selected units.

  The units covered by these nine units are units that fall within the range indicated by the nine solid circles in FIG. 29B obtained as a final result by updating FIG. 27B. .

Further, the selected unit information adjacent to each communication unit 101 is updated as shown in FIG. 28 and shown in FIG.
All the non-selected units are adjacent to any of the nine selected units, as is apparent from FIGS. 29 (a), (b) and FIG.

  FIG. 31 is a flowchart showing a process executed by the server 301 of FIG. 3 in order to realize the above-described selection unit selection process. This operation flowchart is realized by the CPU 3401 executing a control program stored in the memory 3402 or the external storage device 3405 in the server 301 having a hardware configuration shown in FIG.

  First, the selection process of the selected unit is performed by repeating the processes of steps S3101 to S3107 in FIG. 31 until, for example, for all the units shown in FIG. Repeatedly executed. For all the units, when the selected unit is always included in the adjacent units of each unit, for example, the final results shown in FIGS. 29 and 30 are obtained.

  In the repetitive processing from step S3101 to S3107, first, the unit having the smallest number of adjacent units is extracted from the units having no selected unit in the adjacent unit (step S3102 in FIG. 31). This is the same as step 3 described above. This process corresponds to the algorithm (a). In this process, for example, the 11th embodiment (FIG. 17A) in the first embodiment, the 7th embodiment (FIG. 19A) in the second embodiment, and the 20th embodiment (FIG. 21A) in the third embodiment. The communication unit 101 of No. 22 is extracted in Example 4 (FIG. 23A), No. 39 of Example 5 (FIG. 25A), and No. 29 of Example 6. Now, let the communication unit 101 extracted in this way be unit A.

  Next, the broadcast target unit selection process is executed until a path can be established from unit A to GW 102 by the iterative process from steps S3103 to S3106 in FIG. 31 (step S3104 in FIG. 31). This selection process is a process in which adjacent units are sequentially traced from unit A to GW 102 while referring to route information. An adjacent unit that is sequentially traced starting from unit A is defined as a selection processing target unit Y.

  Each time a broadcast target unit is selected as a selected unit in step S3104, if the unit is not already selected, an adjacent unit (selection processing target unit Y) is further traced toward the GW 102 (FIG. 31 is NO in step S3105).

  On the other hand, if the selected unit selected in step S3104 is already selected, the process of tracing the adjacent unit toward the GW 102 for the current unit A ends (the determination in step S3105 in FIG. 31 is YES). Then, the process proceeds from step S3101 to the next repetition process of S3107, and the unit having the next smallest number of neighbors is extracted. This is because, for a selected unit that has already been selected, the route from there to the GW 102 has already been selected and the route should have been established, so there is no need to follow the adjacent unit any further. .

Details of the broadcast target unit selection processing in step S3104 are shown in the flowchart of FIG. Hereinafter, the flowchart of FIG. 32 will be described.
First, in the selection processing target unit Y, the route to the GW 102 is searched by referring to the route information. Then, an adjacent unit located on the shortest route to the GW 102 is extracted from the searched routes (step 3201 in FIG. 32).

  For example, in the first embodiment described above, when No. 11 (unit A) is selected as the selection processing target unit Y in step S3103 for the first time, 15 is set as the adjacent unit on the shortest route from No. 11 to GW 102 in step S3201. One unit is selected. In addition, when No. 15 is selected as the selected unit and is selected as the selection target unit Y in the subsequent step S3103, in step S3201, one unit of No. 26 is set as the adjacent unit on the shortest route from No. 15 to GW102. Is selected.

  In the second embodiment, when No. 7 (unit A) is selected as the selection processing target unit Y in the first step S3103, in step S3201, 25th and 14th as adjacent units on the shortest route from No. 7 to GW102. 2 units are selected. In addition, when No. 25 of the two is selected as the selection unit and is selected as the selection processing target unit Y in the subsequent step S3103, in step S3201, 1 is set as the adjacent unit on the shortest route from No. 25 to GW102. One unit is selected.

  In the third embodiment, when No. 20 (unit A) is selected as the selection processing target unit Y in the first step S3103, the adjacent units on the shortest route from the No. 20 to the GW 102 are 5, 10, Unit 18 is selected. In addition, when No. 5 out of the three is selected as the selected unit and selected as the selection processing target unit Y in the subsequent step S3103, in step S3201, as the adjacent unit on the shortest route from No. 5 to GW 102, 8 is selected. , 9 units are selected.

  In the fourth embodiment, when No. 22 (unit A) is selected as the selection processing target unit Y in step S3103 for the first time, in step S3201, 17th 1 is set as an adjacent unit on the shortest route from No. 22 to GW102. A unit is selected.

  In the fifth embodiment, when No. 39 (unit A) is selected as the selection processing target unit Y in the first step S3103, in step S3201, No. 9, 33 are set as adjacent units on the shortest route from No. 39 to GW102. Units are selected.

  In the sixth embodiment, when No. 29 (unit A) is selected as the selection processing target unit Y in the first step S3103, in step S3201, 32, 37, and the adjacent units on the shortest route from No. 29 to the GW 102 are displayed. Units 38 and 40 are selected. In addition, when No. 40 is selected as the selected unit from among the four units and selected as the selection processing target unit Y in the subsequent step S3103, in step S3201, 17 as the adjacent units on the shortest route from No. 40 to GW 102 are displayed. , 2 units of No. 3 are selected.

After step S3201, it is determined whether or not there is only one Y adjacent unit on the extracted shortest route (step S3202 in FIG. 32).
For example, in the first embodiment described above, when each of units 15 and 26 is extracted in step S3201 in FIG. 32 in the first iteration of steps S3103 to S3106 in FIG. 31, the determination in step S3202 is YES. Become.

  In the second embodiment, when two units 25 and 14 are extracted in step S3201 in the first iteration of steps S3103 to S3106, the determination in step S3202 is NO. Also, when the first unit is extracted in the second iteration, the determination in step S3202 is YES.

  In the third embodiment, when three units Nos. 5, 10, and 18 are extracted in the first iterative process, the determination in step S3202 is NO. Also, when the eighth and ninth units are extracted in the second iteration, the determination in step S3202 is NO.

In the fourth embodiment, when one unit of number 17 is extracted in the first iteration, the determination in step S3202 is YES.
In the fifth embodiment, when two units 9 and 33 are extracted in the first iterative process, the determination in step S3202 is NO.

  In the sixth embodiment, when four units 32, 37, 38, and 40 are extracted in the first iterative process, the determination in step S3202 is NO. Also, when the 17th and 3rd units are extracted in the second iterative process, the determination in step S3202 is NO.

  If there is only one adjacent unit of Y on the shortest route and the determination in step S3202 is YES, the adjacent unit is set as B, and it is determined whether unit B is already a selected unit. (Step S3203 in FIG. 32). In this determination, for example, the unit B on the route information shown in FIGS. 17, 19, 21, 23, 25, 27, etc. is given the mark information of the selected unit (double solid line square in the figure). This is realized as a process for determining whether or not it has been performed.

  If unit B is not a selected unit yet and the determination in step S3203 is NO, step S3210 and then the process of step S3211 are executed. On the other hand, if unit B is already selected and the determination in step S3203 is YES, step S3211 is not executed and step S3211 is executed. The processing of step S3210 and step S3211 will be described later.

  When the number of adjacent units of Y on the shortest route is not only one and the determination in step S3202 is NO, the repetition processing of steps S3204 to S3208 is performed by the number of adjacent units of Y on the shortest route. The following series of processing is repeatedly executed. Here, it is assumed that the adjacent unit of Y on the shortest route targeted in each repetition is B.

  First, it is determined whether or not the unit B is a selected unit (step S3205 in FIG. 32). This determination is realized in the same manner as in step S3203. That is, for example, the unit B on the route information shown in FIGS. 17, 19, 21, 23, 25, 27, 29, etc. has the mark information (double solid line square in the figure) of the selected unit. This is realized as a process for determining whether or not it is given.

  If unit B has already been selected and the determination in step S3205 is YES, the path from unit B to GW 102 has already been established, and there is no need to select another path, so in step S3211 unit B remains unchanged. Selected as a selection unit. In this case, returning to FIG. 31 again, after the end of step S3104, the determination in step S3105 is YES. That is, since the path from the current unit A to the GW 102 has been established, the iterative process from step S3103 to S3106 for the current unit A ends.

  For example, in the sixth embodiment described above, No. 40 is selected as the selection unit in the first iteration of steps S3103 to S3106 in FIG. 31, and is selected as the selection target unit Y in step S3103 of the second iteration. Further, in step S3201 in FIG. 32, two units Nos. 17 and 3 are selected as adjacent units on the shortest route from No. 40 to GW. Then, after the determination in step S3202 of FIG. 32 is NO, the determination in step S3205 is YES when unit B = 17 is processed in the iterative processing from step S3204 to S3208. As a result, in step S3211, unit B = 17 is selected as it is as the selected unit. Further, returning to FIG. 31, after the end of step S3104, the determination in step S3105 is YES. As a result, the route from the 29th unit having the least number of adjacent units to the GW 102 to the GW 102 has been established as GW → 17 → 40 → 29, so that the repetition for the 29th unit from steps S3103 to S3106 in FIG. The process ends.

If unit B is not yet a selected unit and the determination in step S3205 is NO, the next process is executed.
First, among the adjacent units of unit B, the number M of units not covered by the selected unit, that is, the number M of units excluding the selected unit and the adjacent units covered by the selected unit is calculated (FIG. 32). Step S3206). This calculation process is the same as that described in step 3. This is a process for applying the algorithm of (c).

  Next, for an adjacent unit of unit B, a number K exceeding the threshold value N for the number of adjacent selected units is calculated (step S3207 in FIG. 32). More specifically, the following processing is executed on the selected unit information adjacent to each communication unit 101 shown in FIG. 18, FIG. 20, FIG. 22, FIG. That is, in the selected unit information, when unit B is added as a new selected unit to each of the adjacent units of unit B, the total number of selected units exceeds N (for example, 4). The number K is calculated. This calculation process is the same as that described in step 3. This is a process for applying the algorithm (d).

The processes of steps S3206 and S3207 are executed for the number of adjacent units of Y on the shortest route by the repeated processes of steps S3204 to S3208.
After the above iterative process is completed, the unit having the largest number of M calculated in step S3206 among the units having the smallest number K calculated in step S3207 is determined as the unit to be selected. If there are a plurality of units to be selected, the unit having the largest number of adjacent units calculated from the path information is selected (step S3209 in FIG. 32).

  For example, in the above-described second embodiment, in the first iteration of steps S3103 to S3106 of FIG. 31, the 25th and 14th adjacent units on the shortest route from the selection processing target unit Y = 7 to GW102 in step S3201 Two units are selected. At this time, in step S3206 of FIG. 32, the number M of adjacent units excluding the selected unit and the adjacent units that it covers is calculated as 7 and 6, respectively. In step S3207 of FIG. 32, the number K of adjacent units that exceed the threshold value N (for example, 4) in both the 25th and 14th units is 0. Thereby, in step S3209, among the 25th and 14th with the smallest number of K, the 25th unit with the largest number of 7 is the unit to be selected as the selected unit. Determined.

  In the third embodiment, units Nos. 5, 10, and 18 are selected in the first iteration. At this time, in step S3206 of FIG. 32, the number M of adjacent units excluding the selected unit and the adjacent units that it covers is calculated as 8, 4, and 5, respectively. Also, in step S3207 in FIG. 32, the number K of adjacent units that exceed the threshold N (for example, 4) for all three units Nos. 5, 10, and 18 is zero. As a result, in step S3209, among the Nos. 5, 10, and 18 where the number of K is the smallest 0, the No. 5 unit with the largest number of M is the unit to be selected as the selected unit. It is determined. Furthermore, the 8th and 9th units are selected in the second iteration. At this time, in step S3206 in FIG. 32, the number M of adjacent units excluding the selected unit and the adjacent units covered by the selected unit is calculated as 10, 7 respectively. In step S3207 of FIG. 32, the number K of adjacent units that exceed the threshold value N (for example, 4) in both the eighth and ninth units is zero. As a result, in step S3209, among the 8th and 9th, which has the smallest number of K, the 8th unit with the largest number of M, 10 is determined as the unit to be selected as the selected unit. Is done.

  In the fifth embodiment, units 9 and 33 are selected in the first iteration. At this time, in step S3206 in FIG. 32, the number M of adjacent units excluding the selected unit and the adjacent units covered by the selected unit is calculated as 2, 1, respectively. In step S3207 in FIG. 32, the number K of adjacent units that exceed the threshold value N (for example, 4) for both the ninth and 33rd units is zero. As a result, in step S3209, out of the numbers 9 and 33 where the number of K is the smallest 0, the number 9 unit where the number of M is the largest 2 is determined as the unit to be selected as the selected unit. Is done.

  In the sixth embodiment, units 32, 37, 38, and 40 are selected in the first iteration. At this time, in step S3206 of FIG. 32, the number M of adjacent units excluding the selected unit and the adjacent units covered by the selected unit is 1 (4th), 1 (4th), 0, 1 (4 No.) is calculated. Further, in step S3207 in FIG. 32, for the unit 32, K = 2 because the 16th and 19th units appear as adjacent units that exceed the threshold value N (for example, 4). For the units 37 and 40, the number K of adjacent units that exceeds the threshold value N (for example, 4) is 0. Further, the number of adjacent units of No. 32 is 11, the number of adjacent units of No. 37 is 8, and the number of adjacent units of No. 40 is 9. As a result, in step S3209, among the 37th and 40th numbers having the smallest number of K and the largest number of M, the number 40 unit having the largest number of 9 adjacent units is selected as the selected unit. It is determined that the unit should be selected.

  As described above, the process of step S3210 is executed for the unit determined as the selection target in step S3209 or step S3203 of FIG. Here, the adjacent units of the unit determined in step S3209 or S3203 are extracted from the route information of FIG. 17, FIG. 19, FIG. 21, FIG. Then, in the selected unit information adjacent to each communication unit 101 shown in FIG. 18, FIG. 20, FIG. 22, FIG. 26, etc., in each unit column extracted from the path information, in step S3209 or S3203. Newly selected units are additionally registered.

In step S3211, the unit determined as the selection target in step S3209 or step S3203 in FIG. 32, or the unit determined as the unit already selected in step S3203 or S3205 is selected as the selected unit.
The process of selecting the broadcast target unit in step S3104 of FIG. 31 is realized by the process of the flowchart of FIG.

  By the processing of the embodiment described above, the server 301 selects the communication unit 101 that performs broadcast transfer, so that packets flowing through the wireless network can be suppressed, network traffic can be reduced, and packet arrival accuracy is improved. To do.

According to the present embodiment, the traffic state of the wireless network can be reduced to 1/3 or less as compared with the prior art. In the prior art, the amount of information of the wireless network is, for example,

(1 gateway + 35 communication units) x packet size

It becomes. On the other hand, the information amount of the ad hoc wireless network according to the present embodiment is, for example,
(1 gateway + 10 communication units) x packet size

It can be.

  FIG. 33 is a diagram showing a traffic state of the wireless network by packet transfer in this embodiment. In the present embodiment, not all communication units at a specific distance are set as broadcast transfer permission targets, but communication units at a broadcast transfer permission target are selected by further narrowing down targets from among communication units at a specific distance. At this time, a selection is made so that the radio wave reach ranges from the selected communication units do not overlap. For this reason, the traffic of the wireless network can be further reduced as compared with the prior art, and broadcasting can be performed more efficiently. In the present embodiment, it is possible to dynamically change the broadcast target unit to cope with a change in wireless quality due to weather.

FIG. 34 is a diagram illustrating an example of a hardware configuration of a computer capable of realizing the server 301 of FIG. 3 according to the present embodiment.
The computer shown in FIG. 34 includes a CPU 3401, a memory 3402, input / output devices 3403 and 3404, an external storage device 3405, a portable recording medium driving device 3406 into which a portable recording medium 3409 is inserted, and a communication interface 3407. These are connected to each other by a bus 3408. The configuration shown in the figure is an example of a computer that can implement the above system, and such a computer is not limited to this configuration.

  The CPU 3401 controls the entire computer. The memory 3402 is a memory such as a RAM that temporarily stores a program or data stored in the external storage device 3405 (or the portable recording medium 3409) when executing a program, updating data, or the like. The CUP 3401 performs overall control by reading the program into the memory 3402 and executing it.

  The input / output devices 3403 and 3404 detect an input operation by a user using a keyboard, a mouse, or the like, notify the CPU 3401 of the detection result, and output data transmitted by the control of the CPU 3401 to a display device or a printing device.

The external storage device 3405 is, for example, a hard disk storage device. Mainly used for storing various data and programs.
The portable recording medium driving device 3406 accommodates a portable recording medium 3409 such as an optical disk, SDRAM, or CompactFlash (registered trademark), and has an auxiliary role for the external storage device 3405.

The communication interface 3407 is a device for connecting, for example, a LAN (local area network) or WAN (wide area network) communication line.
The system according to the present embodiment is realized by the CPU 3401 executing a control program corresponding to the flowcharts of FIGS. 31 and 32 that realize the functions of the present embodiment. The program may be recorded and distributed in, for example, the external storage device 3405 or the portable recording medium 3409, or may be acquired from the network by the communication interface 3407. Each data used in the control program is stored and operated on, for example, the external storage device 3405 or the memory 3402. In addition, a work area for executing the control program is developed on the memory 3402 as necessary.

Regarding the above embodiment, the following additional notes are disclosed.
(Appendix 1)
In a packet transfer method executed by a control device connected to a network composed of a plurality of communication units and controlling packet transfer in any of the communication units,
The control device refers to adjacent unit information related to communication units adjacent to each communication unit stored in the storage unit, and route information indicating a route between each communication unit and the control device. Selecting a communication unit to which a packet received from another communication unit or the control device is broadcast-transferred,
Generating a packet including information indicating the selected communication unit to be broadcasted, and transmitting the packet to any of the plurality of units;
A broadcast transfer method comprising: (1, FIGS. 7 to 15 and FIGS. 31, 32)
(Appendix 2)
In the selection process of the broadcast target unit, the broadcast target unit is selected so as to perform broadcast transfer to a communication apparatus having a small number of adjacent communication apparatuses.
The broadcast packet transfer method according to supplementary note 1, wherein: (2, Fig. 31)
(Appendix 3)
In the broadcast target unit selection process, the broadcast target unit is selected based on the route information such that the route from the communication device that is the distribution source of the broadcast packet is the shortest route.
The broadcast packet transfer method according to supplementary note 1, wherein: (3, Fig. 32)
(Appendix 4)
In the broadcast target unit selection process, the broadcast target unit is selected so as to cover more adjacent communication devices that cannot be covered by the already selected broadcast target unit.
The broadcast packet transfer method according to supplementary note 1, wherein: (4, Fig. 32)
(Appendix 5)
In the broadcast target unit selection process, an upper limit number of broadcast target units included in a communication device adjacent to each communication device is set, and the broadcast target unit is selected so as not to exceed the upper limit number.
The broadcast packet transfer method according to supplementary note 1, wherein: (5, Fig. 32)
(Appendix 6)
Repeatedly executing the broadcast target unit selection process so that the broadcast packet is distributed to all the communication devices;
The broadcast packet transfer method according to supplementary note 1, wherein: (6, Fig. 31, 32)
(Appendix 7)
The step of selecting the broadcast target unit includes:
A first step of selecting the broadcast target unit to perform broadcast transfer to a communication unit having the smallest number of adjacent communication units;
A second step of selecting the broadcast target unit based on the route information so that a route from a communication unit that is a distribution source of the broadcast packet has a minimum number of hops;
A third step of selecting the broadcast target unit to cover more adjacent communication units that cannot be covered by the already selected broadcast target unit;
Consist of,
The broadcast packet transfer method according to supplementary note 1, wherein: (7)
(Appendix 8)
A fourth step of setting an upper limit number of broadcast target units included in a communication device adjacent to each communication device and selecting the broadcast target unit so as not to exceed the upper limit number;
The broadcast packet transfer method according to appendix 7, wherein: (8)
(Appendix 9)
Repeatedly performing the first, second, third and fourth steps until all units to which a packet is to be transmitted are covered;
9. The broadcast packet transfer method according to appendix 8, wherein: (9)
(Appendix 10)
A control device that is connected to a network composed of a plurality of communication units and controls packet transfer in any of the communication units,

A storage unit storing adjacent unit information indicating a communication unit adjacent to the communication unit for each communication unit, and path information indicating a path between each communication unit and the control device;
With reference to the adjacent unit information and the path information, a selection unit that selects a communication unit to which a packet received from another communication unit or the control device is to be broadcast-transmitted among the plurality of communication units;
A broadcast transfer apparatus comprising: a transmission unit that generates a packet including information indicating the selected communication unit to be broadcast-transferred and transmits the packet to any one of the plurality of units. (10)
(Appendix 11)
In the selection process of the broadcast target unit, the broadcast target unit is selected so as to perform broadcast transfer to a communication apparatus having a small number of adjacent communication apparatuses.
The broadcast packet transfer apparatus according to Supplementary Note 10, wherein
(Appendix 12)
In the broadcast target unit selection process, the broadcast target unit is selected based on the route information such that the route from the communication device that is the distribution source of the broadcast packet is the shortest route.
The broadcast packet transfer apparatus according to Supplementary Note 10, wherein
(Appendix 13)
In the broadcast target unit selection process, the broadcast target unit is selected so as to cover more adjacent communication devices that cannot be covered by the already selected broadcast target unit.
The broadcast packet transfer apparatus according to Supplementary Note 10, wherein
(Appendix 14)
In the broadcast target unit selection process, an upper limit number of broadcast target units included in a communication device adjacent to each communication device is set, and the broadcast target unit is selected so as not to exceed the upper limit number.
The broadcast packet transfer apparatus according to Supplementary Note 10, wherein
(Appendix 15)
A control device connected to a network composed of a plurality of communication units and controlling packet transfer in any of the communication units,
Other communication units among a plurality of communication units with reference to adjacent unit information related to communication units adjacent to each communication unit stored in the storage unit and path information indicating a path between each communication unit and the control device Or selecting a communication unit to broadcast-transmit a packet received from the control device;
Generating a packet including information indicating the selected communication unit to be broadcasted, and transmitting the packet to any of the plurality of units;
A program that executes (11)
(Appendix 16)
In the selection process of the broadcast target unit, the broadcast target unit is selected so as to perform broadcast transfer to a communication apparatus having a small number of adjacent communication apparatuses.
The program according to supplementary note 15, characterized by:
(Appendix 17)
In the broadcast target unit selection process, the broadcast target unit is selected based on the route information such that the route from the communication device that is the distribution source of the broadcast packet is the shortest route.
The program according to supplementary note 15, characterized by:
(Appendix 18)
In the broadcast target unit selection process, the broadcast target unit is selected so as to cover more adjacent communication devices that cannot be covered by the already selected broadcast target unit.
The program according to supplementary note 15, characterized by:
(Appendix 19)
In the broadcast target unit selection process, an upper limit number of broadcast target units included in a communication device adjacent to each communication device is set, and the broadcast target unit is selected so as not to exceed the upper limit number.
The program according to supplementary note 15, characterized by:
(Appendix 20)
Repeatedly executing the broadcast target unit selection process so that the broadcast packet is distributed to all the communication devices;
The program according to supplementary note 15, characterized by:

101 communication unit 102 gateway 301 server 402 ad hoc FPGA

Claims (11)

In a packet transfer method executed by a control device connected to a network composed of a plurality of communication units and controlling packet transfer in any of the communication units,
The control device refers to adjacent unit information related to communication units adjacent to each communication unit stored in the storage unit, and route information indicating a route between each communication unit and the control device. Selecting a communication unit to which a packet received from another communication unit or the control device is broadcast-transferred,
Generating a packet including information indicating the selected communication unit to be broadcasted, and transmitting the packet to any of the plurality of units;
A broadcast transfer method comprising: In the selection process of the broadcast target unit, the broadcast target unit is selected so as to perform broadcast transfer to a communication apparatus having a small number of adjacent communication apparatuses.
The broadcast packet transfer method according to claim 1, wherein: In the broadcast target unit selection process, the broadcast target unit is selected based on the route information such that the route from the communication device that is the distribution source of the broadcast packet is the shortest route.
The broadcast packet transfer method according to claim 1, wherein: In the broadcast target unit selection process, the broadcast target unit is selected so as to cover more adjacent communication devices that cannot be covered by the already selected broadcast target unit.
The broadcast packet transfer method according to claim 1, wherein: In the broadcast target unit selection process, an upper limit number of broadcast target units included in a communication device adjacent to each communication device is set, and the broadcast target unit is selected so as not to exceed the upper limit number.
The broadcast packet transfer method according to claim 1, wherein: Repeatedly executing the broadcast target unit selection process so that the broadcast packet is distributed to all the communication devices;
The broadcast packet transfer method according to claim 1, wherein: The step of selecting the broadcast target unit includes:
A first step of selecting the broadcast target unit to perform broadcast transfer to a communication unit having the smallest number of adjacent communication units;
A second step of selecting the broadcast target unit based on the route information so that a route from a communication unit that is a distribution source of the broadcast packet has a minimum number of hops;
A third step of selecting the broadcast target unit to cover more adjacent communication units that cannot be covered by the already selected broadcast target unit;
Consist of,
The broadcast packet transfer method according to claim 1, wherein: A fourth step of setting an upper limit number of broadcast target units included in a communication device adjacent to each communication device and selecting the broadcast target unit so as not to exceed the upper limit number;
The broadcast packet transfer method according to claim 7. Repeatedly performing the first, second, third and fourth steps until all units to which a packet is to be transmitted are covered;
9. The broadcast packet transfer method according to claim 8, wherein: A control device that is connected to a network composed of a plurality of communication units and controls packet transfer in any of the communication units,

A storage unit storing adjacent unit information indicating a communication unit adjacent to the communication unit for each communication unit, and path information indicating a path between each communication unit and the control device;
With reference to the adjacent unit information and the path information, a selection unit that selects a communication unit to which a packet received from another communication unit or the control device is to be broadcast-transmitted among the plurality of communication units;
A broadcast transfer apparatus comprising: a transmission unit that generates a packet including information indicating the selected communication unit to be broadcast-transferred and transmits the packet to any one of the plurality of units. A control device connected to a network composed of a plurality of communication units and controlling packet transfer in any of the communication units,
Other communication units among a plurality of communication units with reference to adjacent unit information related to communication units adjacent to each communication unit stored in the storage unit and path information indicating a path between each communication unit and the control device Or selecting a communication unit to broadcast-transmit a packet received from the control device;
Generating a packet including information indicating the selected communication unit to be broadcasted, and transmitting the packet to any of the plurality of units;
A program that executes