JP2015053627A - Communication system control method, communication system, and control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which when a center side controls a large number of sensor nodes, it is difficult to perform efficient processing due to a bottle neck of a mobile public network.SOLUTION: A control method is a control method of a communication system including a network, a plurality of terminals, and a control device connected with the network for communicating with each of the terminals via the network. The control device includes: an interface connected with the network; a processor connected with the interface; and a storage unit connected with the processor. The control method of the communication system includes: a first procedure of determining communication order with the plurality of terminals so that the control device preferentially selects, as a next communication object, a terminal away more than a prescribed distance from a terminal with which communication was performed the previous time from the plurality of terminals; and a second procedure of the control device performing communication with each of the plurality of terminals via the network in the determined order.

Description

  The present invention relates to a control method for a communication system.

  As background art in this technical field, there is JP-A-8-139806 (Patent Document 1). This publication states that “an object of the present invention is to provide a data aggregation method and a data aggregation system capable of operating a center to the limit and minimizing call loss processing unnecessary for the network. The present invention has means for measuring the congestion status of the public network and the center, and means for operating the public network, the center and the terminal in a coordinated manner so that the measured congestion status shifts in the direction of improvement. Have been described.

JP-A-8-139806

  The mainstream of sensor networks using mobile communication network, which is currently spreading, is a sensor autonomous method, that is, a method of starting packet communication from a communication module installed on the sensor side and transmitting sensor data to a server. It has become. When sending information from the sensor side, real-time and responsiveness cannot be supported. On the other hand, IP connection using packet communication by a polling method from the center side to the sensor side is also possible, and data reception near real time is possible. However, the network of the mobile communication carrier is constructed on the assumption that a large number of calls from the terminal side and the start of packet communication by the large number of terminals are processed, but the center side performs IP communication to a large number of terminals. This is not expected. For this reason, it is difficult to efficiently process a large number of sensor devices from the center side in a limited time due to the core network of the mobile public network and the bottleneck of the wireless network (bottleneck of wireless bandwidth, processing performance, etc.). There are challenges. When performing IP data communication by polling a large number of sensor nodes from the center side, it is necessary to estimate the status of the mobile communication carrier network and perform processing distribution.

  In order to solve the above-described problems, the present invention provides a control method for a communication system including a network, a plurality of terminals, and a control device that is connected to the network and communicates with each of the terminals via the network. The control device includes an interface connected to the network, a processor connected to the interface, and a storage device connected to the processor, and the control method of the communication system includes the control Communication with the plurality of terminals so that the apparatus preferentially selects one terminal that is more than a predetermined distance from the terminal that performed the previous communication among the plurality of terminals as a target of the next communication. A first procedure for determining the order of the communication, and the control device communicates with each of the plurality of terminals via the network in the determined order. Characterized in that it comprises a step 2, the.

  According to an embodiment of the present invention, it is possible to efficiently control terminals such as a large number of sensor nodes from the center side while avoiding the concentration of a load on a specific communication facility.

It is a block diagram which shows the structure of the whole communication system of embodiment of this invention. It is explanatory drawing of the division area position management table which the center installation of embodiment of this invention hold | maintains. It is explanatory drawing of the sensor node position management table which the center installation of embodiment of this invention hold | maintains. It is a flowchart which shows the whole process which the center installation of embodiment of this invention performs. It is explanatory drawing which shows the area division process of the initial stage which the center installation of embodiment of this invention performs. It is a flowchart which shows the area division process of the initial stage which the center installation of embodiment of this invention performs. It is explanatory drawing which shows the process which the center installation of embodiment of this invention maps a sensor node to the area of the divided | segmented level 1. FIG. It is a flowchart which shows the process which the center equipment of embodiment of this invention maps a sensor node to the area of the divided | segmented level 1. FIG. It is explanatory drawing which shows the optimization process of the division area which the center installation of embodiment of this invention performs. It is a flowchart which shows the optimization process of the division area which the center installation of embodiment of this invention performs. It is a flow figure showing selection of a sensor node which starts processing, and a processing method which center facilities of an embodiment of the present invention perform. It is the 1st part of the 1st flowchart which shows selection of a sensor node to process next, and a processing system which center equipment of an embodiment of the present invention performs. It is a 2nd part of the 1st flowchart which shows selection of the sensor node to process next, and a processing system which the center installation of embodiment of this invention performs. It is a 2nd flowchart which shows the selection of the sensor node to process next, and the processing system which the center installation of embodiment of this invention performs. It is a 1st part of the 3rd flowchart which shows selection of a sensor node to process next, and a processing system which the center installation of embodiment of this invention performs. It is a 2nd part of the 3rd flowchart which shows selection of the sensor node to process next, and a processing system which the center installation of embodiment of this invention performs. It is explanatory drawing which shows distribution of the response time which the center installation of embodiment of this invention acquired. It is a flowchart which shows the processing system based on the response time which the center installation of embodiment of this invention performs. It is explanatory drawing of the adjacent area in embodiment of this invention. It is explanatory drawing of the search method of the adjacent area in embodiment of this invention. It is explanatory drawing of the adjacent area search information table referred when the center facility of embodiment of this invention searches an adjacent area. It is a flowchart which shows the process in which the center installation of embodiment of this invention extracts an adjacent area. It is a specific example of the area divided | segmented in embodiment of this invention, and the number of sensor nodes distributed to each area.

  The embodiment of the present invention described below estimates a bottleneck of the public network when controlling a large number of sensor devices from the center device using the mobile public network, and without changing the carrier equipment, In addition, it is a control method for efficiently processing requests for sensor devices from the center side. Specifically, when data communication processing is performed from the center side to the sensor device, the position of the sensor terminal based on the GPS information, the congestion degree of each region, and the response time of the sensor node are grasped, and the IP data of the mobile public network This is a method for efficiently processing requests from the center side to the sensor device so as not to exceed the communication processing upper limit. Specifically, this embodiment includes the following two processes.

・ Regional distributed processing Although the bottleneck of the mobile communication network is divided into the core network and the wireless network part, each area is designed to take into account the request from the center for one area. Processing cannot be performed when concentrated. Therefore, if the area to be communicated is distributed and a request is made, processing can be performed efficiently. Since the sensor device may be moving, the center collects GPS information from the sensor device to know the area to which the sensor device belongs, grasps the distribution information for the latest area, and selects the area. Consciously send a processing request to the sensor device.

・ Processing by response time Efficient processing is performed according to the response time of each sensor node collected at the time of regional distributed processing.

  Hereinafter, details of embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing the overall configuration of a communication system according to an embodiment of the present invention. With reference to FIG. 1, the outline of the processing method to the sensor node for reducing the load on the mobile network will be described.

  The communication system 101 of the present embodiment includes a center facility 104 that performs sensor node control, a plurality of sensor nodes 103, and a mobile communication carrier network (mobile network) 105.

  The center facility 104 is realized by a computer having a processor 110, a storage device 111, and an interface 112 connected to each other. The processing executed by the center facility 104 described later is actually realized by the processor 110 executing a program (not shown) stored in the storage device 111. The storage device 111 further stores a divided area position management table 201 (see FIG. 2) and a sensor node position management table 301 (see FIG. 3), which will be described later.

  The mobile network 105 may be a general mobile communication carrier network, and includes, for example, a plurality of gateway devices 107 and a plurality of base stations 108. Each base station 108 performs wireless IP data communication with each sensor node 103.

  The service area 109 is a range where services are provided via the mobile network 105. Any service may be provided. In the service area 109, a plurality of sensor nodes 103 to be serviced are arranged. Each sensor node 103 may be fixed at a predetermined position, or may move like a mobile phone terminal.

  Each sensor node 103 includes a sensor that measures a physical quantity and a communication unit that communicates data. For example, when the communication unit of each sensor node 103 receives a request from the center facility 104 via the mobile network 105, the communication unit transmits data including the physical quantity measured by the sensor to the center facility 104 in response to the request. Further, each sensor node 103 may have a GPS signal receiver, acquire position information based on the GPS signal received from the GPS 102, and transmit it to the center facility 104.

  Each sensor node 103 may be of any type, but examples of the fixed sensor node 103 include a watt-hour meter (so-called smart meter) having a communication function. The center facility 104 sequentially transmits requests to all the sensor nodes 103, and each sensor node 103 that has received the request responds to the center facility 104 with data including the amount of power measured by the sensor. Further, examples of the movable sensor node 103 include a mobile phone terminal, a portable information terminal such as a so-called smartphone, or a vehicle having a sensor and a communication function such as a so-called probe car. These also respond to the data acquired by the sensor in response to a request from the center facility 104.

  In the present embodiment, the center facility 104 estimates the facility status of the mobile network 105, and divides the service area 109 into a plurality of districts (areas) 106 having an optimal size. Further, the center facility 104 performs mapping processing of the divided areas and the positions of the sensor nodes 103 based on the position information of the sensor nodes 103, and geographically distributed IP data communication based on the mapping result. I do. In addition, for the sensor node 103 that is determined that the degree of congestion of the mobile network 105 is low based on the response status of each sensor node 103, time-sharing processing is performed without being aware of geographical factors.

  FIG. 2 is an explanatory diagram of the divided area position management table 201 held by the center facility 104 according to the embodiment of this invention.

  The divided area position management table 201 is a table representing divided areas for grouping the distribution of the sensor nodes 103, and is recorded in a write-once type. The sensor node 103 is assumed to be a moving body or a fixed one, and each sensor node 103 has a position coordinate. Sensor nodes 103 used in a certain service are distributed in the service area 109. In the present embodiment, the service area 109 is divided so that management is easy. Each sensor node 103 belongs to one of the divided areas.

  The divided area position management table 201 records area information obtained by basic division of the service area 109 according to a rule, and area information further divided to subdivide management according to the degree of congestion of the sensor nodes 103. Further subdivided areas are added to the divided area position management table 201 after recording the basic divided areas.

  The divided area position management table 201 includes an area specific number 211, an area level number 212, a latitude / longitude (northwest end) 213, a latitude / longitude (southeast end) 214, a number 215 of sensor nodes in the area, an upper level specific number 216, A higher level unique number 217 is included.

  The area unique number (111) is an identifier for uniquely identifying each area 106. For example, when the service area 109 is basically divided in a lattice pattern by an equally spaced boundary line in the north-south direction and an equally spaced boundary line in the east-west direction, each of the divided rectangular areas 106 may have A, B, C. A unique number is given. For example, unique numbers such as A, B, C,... May be sequentially given from the northwest area 106 to the southeast area 106.

  The basic divided area 106 is managed as “area level 1 (highest level)”. The area level number 212 indicates the area level of each area 106. As will be described later, the basic divided area 106 may be divided into smaller areas, but a lower level (such as area level 2 or 3) is given to such fine areas.

  The position and size of each area 106 can be expressed using two points of latitude and longitude information, for example, the latitude and longitude 213 at the northwest end and the latitude and longitude 214 at the southeast end of each area 106. The basic divided area 106 is an area generated at an initial stage and is not changed unless the service area 109 is changed.

  There are a plurality of sensor nodes 103 in the service area 109. From the coordinate data of each sensor node 103, the number of sensor nodes 103 belonging to each area 106 (that is, located in each area 106) can be counted. Recorded in the number 215 of sensor nodes in the area. Whether or not the sensor node 103 exists in the area 106 includes the latitude / longitude information (xx.yyy) at the northwest end of the area information, the position information (aa.bbb) at the southwest end, and the position information (cc .Ddd), whether or not xx> cc> aa and bbb> ddd> yyy (in the case of west longitude) is satisfied.

  When the center equipment 104 connects to the sensor node 103 (for example, transmits a request), if the request is continuously transmitted to the area 106 where a large number of sensor nodes 103 are registered, congestion, response delay, or May affect other services. For this reason, the area 106 is subdivided according to the number of distributions of the sensor nodes 103. Details of the subdivision will be described later with reference to FIGS. The subdivided area goes down one level.

  For example, the area A may be divided into four areas by boundary lines in the north-south direction and the east-west direction passing through the center of the area A. Of the four divided areas, the upper left (northwest), upper right (northeast), lower left (southwest) and lower right (southeast) areas are areas A1, A2, A3, and A4, respectively. The area levels of these areas A1 to A4 are “2”, which is one lower than the highest level.

  The divided area A1 and the like are added to the divided area position management table 201. Specifically, an area unique number 211 that uniquely identifies each divided area, an area level number 212 indicating the level of each divided area, coordinate information 213, 214 of two points of those areas, and their The number of sensor nodes 215 in the area is registered. Furthermore, the identifier of the area of the upper level including those areas (the identifier of the area A including areas A1 to A4 in the above example) is registered in the upper level unique number 216, and the highest level including these areas is registered. The area identifier of the level (similarly, the identifier of area A in the above example) is registered in the highest level unique number (117).

  When the area is subdivided as described above, the value of the number of sensor nodes 215 in the area related to the upper level area including the subdivided area is deleted. For example, when area A is subdivided into areas A1 to A4, the number 215 of sensor nodes in the area related to area A is deleted.

  When a larger number of sensor nodes are registered in the subdivided area, the area is further divided, and information regarding each divided area is added to the divided area position management table 201.

  FIG. 3 is an explanatory diagram of the sensor node position management table 301 held by the center facility 104 according to the embodiment of this invention.

  The sensor node position management table 301 is a table representing the relationship between the information of the sensor node 106 and the area to which it belongs, and is recorded in a write-once type. The information included in the sensor node position management table 301 includes a sensor node number 311, latitude / longitude information 312, belonging area specific number 313, area level number 314, top level specific number 315, processing result 316, and response time 317. .

  Each sensor node 106 is assigned a unique sensor node number (serial number) 311 that is uniquely determined, and is uniquely managed thereby. Each sensor node 106 has position information, and position coordinate information acquired from GPS information is recorded in latitude / longitude information 312. Since each sensor node 106 belongs to one of the areas, the unique number and level of the area to which the sensor node 106 belongs, and the unique number of the area at the highest level including the area are the assigned area unique number 313 and the area level number 314, respectively. And a unique number (L1 area) 315 at the highest level. Since the affiliation area may be subdivided by the denseness of the sensor nodes 106, these pieces of information are updated as appropriate. In addition, when request processing for a sensor node described later (after FIG. 11) is performed, a result (OK / NG) and a response time are recorded as a processing result 316 and a response time 317. The processing result 316 and the response time 317 are updated according to the processing result when the request processing is performed.

  FIG. 4 is a flowchart showing the entire processing executed by the center facility 104 according to the embodiment of this invention.

  First, the center facility 104 performs a process (1 item, step 401) for dividing the service area 109 into appropriate areas 106. Details of this processing will be described later with reference to FIGS. Next, the center facility 104 performs a process of grasping the positional relationship between the divided area 106 and the sensor node 103, that is, a mapping process between the divided area and the sensor node (term 2, step 402). Details of this processing will be described later with reference to FIGS. Next, the center facility 104 performs a process of further dividing the divided area 106 based on the distribution status of the sensor nodes 103, that is, a divided area optimization process (3 items, step 403). Details of this processing will be described later with reference to FIGS.

  Next, the center facility 104 performs the process of selecting the sensor node 103 that performs the actual process, that is, the selection of the sensor node that starts the process and the processing method (4-1, step 404). Details of this processing will be described later with reference to FIG. Next, the center facility 104 selects and determines the sensor node 103 to be processed next, that is, the selection and processing method of the sensor node to be processed next (4- Items 2 to 404, steps 405 to 407) are performed. Details of these processes will be described with reference to FIGS. A specific example of the processing in steps 404 to 407 will be described with reference to FIG. Next, the center facility 104 performs a process that takes the response time into account, that is, a processing method based on the response time (Section 5, Step 408). Details of this processing will be described with reference to FIGS.

  A series of processing to the sensor node 103 is completed by the above processing. However, the sensor node 103 is not necessarily fixed and may move. When the process to the moving sensor node 103 is performed, it is estimated that the mapping state between the area 106 and the sensor node 103 in the above process changes with time. That is, it is necessary to cope with the position change frequency of the sensor node 103 and the change of the communication environment (environment change due to increase or decrease of other service nodes or other mobile devices included in the area where the sensor node exists).

  Therefore, after a certain period of time has passed, depending on the content of the M2M (Machine-to-Machine) service (how often the processing to the sensor node 103 is executed, the frequency of position change, and the change in the communication environment) It is necessary to redo the mapping process between 106 and the sensor node 103. For example, in a service in which processing to the sensor node 103 is executed every 10 minutes, if the sensor node 103 is expected to move across the area 106 in units of 30 minutes, it may be reviewed once every 30 minutes. Conceivable. In such a case, after the end of step 408, the center facility 104 determines whether or not the mapping update time has arrived (step 409), and if it has arrived (in the above example, 30 times from the previous update). If the minutes have passed), the processing after step 402 may be executed again. The actual review time needs to be determined from the viewpoint of system load and efficiency, such as considering the case where the processing speed is reduced from the processing log. Further, when the end of the service, the change of the service area, or the like occurs instead of the update time of the sensor node position information, the process ends (step 409).

  FIG. 5 is an explanatory diagram illustrating an area division process at an initial stage executed by the center facility 104 according to the embodiment of this invention.

When there is a service area 501 that can be used by the sensor node 103 (corresponding to the service area 109 in FIG. 1), the position of the center 502 of the area can be calculated from the coordinates of the two points at the end of the service area 501, and from the center 502, For example, the area 503 is divided by equidistant boundary lines in the north-south direction and the east-west direction. In the example of FIG. 5, the service area 501 is divided into a plurality of areas 503 of √10 km square. Each square region having an area of 10 km ² surrounded by a dotted boundary line shown in FIG. 5 is an area 503, and each corresponds to the area 106 in FIG.

  According to the above procedure, the entire outer periphery of the plurality of areas 503 is expanded until the service area 501 is included. As a result, as shown in FIG. 5, any point in the service area 501 is always included in any area 503. The area level of the divided area 503 is “1”, and is fixed unless the service area 501 is changed.

  FIG. 6 is a flowchart showing area division processing at an initial stage executed by the center facility 104 according to the embodiment of this invention.

The service area 501 is an area for performing the M2M service, and the service area 501 is divided into Nkm ² areas that are assumed as the size of a general base station cover area of the communication carrier network (N: for example, 10 km) ² ).

As described with reference to FIG. 5, the divided area 503 is generated by dividing the space including the service area 501 by 10 km ² until the entire outer periphery of the divided area 503 includes the service area 501. (Step 601). The center facility 104 divides the divided area information into an area specific number 211, an area level number 212, a latitude / longitude (northwest end) 213, a latitude / longitude (southeast end) 214, an upper level specific number 216, The highest level unique number (L1 area) 217 is recorded (step 602).

  FIG. 7 is an explanatory diagram illustrating a process in which the center facility 104 according to the embodiment of this invention maps sensor nodes to divided level 1 areas.

  FIG. 7 shows 14 sensor nodes 701 distributed in the service area 501 as an example. Each sensor node 701 corresponds to the sensor node 103 shown in FIG. Lowercase alphabets “a” to “n” displayed on each sensor node 701 are unique numbers of the sensor nodes 701.

  The center facility 104 maps the coordinate data of each sensor node 701 to the divided level 1 area 503, and determines whether it belongs to each area. In the example of FIG. 7, the space including the service area 501 is divided into 24 areas 503 of 6 × 4, for example, the sensor node a (701) belongs to the level 1 area 503 identified by the unique number E. Similarly, the sensor nodes b to n belong to any one level 1 area 503.

  The center facility 104 registers the mapped result in the sensor node position management table 301. Furthermore, the center facility 104 counts the number 215 of sensor nodes in the area of the unique area number of level 1 to which each sensor node 701 of the divided area position management table 201 belongs according to the mapping result.

  FIG. 8 is a flowchart illustrating a process in which the center facility 104 according to the embodiment of this invention maps the sensor node to the divided level 1 area.

  The center facility 104 acquires the unique number and position information of each sensor node 701 using the GPS information of each sensor node 701, and based on the information, the sensor node number 311 and the latitude of the sensor node position management table 301 are obtained. Longitude information 312 is recorded (step 801). A sensor node number 311 is assigned a number that uniquely determines each sensor node 701. In the example of FIGS. 3 and 7, “a” or the like is given for convenience, but for example, a serial number of a product may be used.

  For example, when each sensor node 701 is fixed and its position information is known, the GPS information is not used and the known position information is recorded in advance in the latitude / longitude information 312 of the sensor node position management table 301. May be.

  Next, based on the latitude and longitude of each sensor node 701 acquired in step 801 and the latitude and longitude (northwest end) 213 and latitude and longitude (southeast end) 214 of the divided area position management table 201, the center facility 104 For the area 503 to which the sensor node 701 belongs, the belonging area unique number 313, the area level number 314, and the highest level unique number (L1 area) 315 are recorded (step 802).

  Next, the center facility 104 refers to the affiliation area unique number 313 of the sensor node position management table 301 and records information in the number 215 of sensor nodes in the area of the divided area position management table 201 based on the value. (Step 803). In the case of FIG. 7, for example, since sensor nodes c and n belong to area E, the value of the number of sensor nodes 215 in the area related to area E is “2”.

  FIG. 9 is an explanatory diagram illustrating a division area optimization process executed by the center facility 104 according to the embodiment of this invention.

  Specifically, FIG. 9 shows a method for subdividing an area and a method for mapping a sensor node to a subdivided area. For the sake of explanation, FIG. 9 shows an example of sensor node distribution different from FIG. In this example, the area 901 of the area level 1 is divided into four to define four areas 902 of the area level 2, and the positional relationship between the area 902 of the area level 2 and the plurality of sensor nodes 701 is shown. Yes. Seven sensor nodes 701 (that is, sensor nodes a to g) are distributed in the area 901. When the area 901 is re-differentiated, each sensor node 701 belongs to one of the areas 902.

  FIG. 10 is a flowchart showing the division area optimization processing executed by the center facility 104 according to the embodiment of this invention.

In an area where sensor nodes are concentrated, there is a possibility that, for example, a telecommunications carrier is performing facility enhancement such as addition of base stations in the mobile network 105. That is, even if the area of the cover area of the normal base station 108 is about 10 km ² , the base stations 108 are installed at a higher density in areas where the concentration of sensor nodes is normal (for example, in the city center). The coverage area of the base station 108 in such an area may be significantly smaller than about 10 km ² . Therefore, the center facility 104 further subdivides the area.

  The segmentation of the area is performed based on, for example, an upper limit (X) of the number of IP packets that can be communicated per unit time by one base station 108 determined by a communication carrier. The center facility 104 determines whether or not there are more sensor nodes 701 than X in each area (step 1001), and the area having more sensor nodes 701 than X (hereinafter, “target” in the description of FIG. 10). Subdivision processing is performed for “area”).

  Specifically, the center facility 104 defines a new (subdivided) area by dividing the target area into four by a north-south boundary line and an east-west boundary line passing through the center of the target area. . Thus, an area defined by further dividing an already defined area is defined as an area at a lower level of the area level before division. For example, the area level of each area 902 defined by dividing the area 901 of area level 1 into four is “2”, which is one level lower than “1”.

  Next, the center facility 104 adds entries corresponding to the newly defined four areas to the divided area position management table 201 (step 1003), and adds the area specific number 211, area level number 212, latitude / longitude ( Information about each area is recorded in the northwest end) 213, the latitude longitude (southeast end) 214, the upper level unique number 216, and the highest level unique number (L1 area) 217 (step 1004).

  Next, the center facility 104 uses the latitude / longitude (northwest end, southeast end) information of the added area and the latitude / longitude of the sensor node and the assigned area specific number 313, area for each sensor node in the sensor node position management table 301. The level number 314 and the highest level unique number (L1 area) 315 are updated (step 1005).

  Next, the center facility 104 refers to the “affiliated area unique number 313” of the sensor node position management table 301 and stores information on the number of sensor nodes 215 in the area of the divided area position management table 201 regarding the newly defined area. At the same time, the value of the number of sensor nodes 215 in the area related to the upper level area including the newly defined area is deleted (step 1006). The process is executed from the highest entry of 201 to the last entry in order.

  When the area subdivided as described above satisfies a predetermined condition, the center facility 104 may further subdivide it. For example, among the four subdivided areas 902 in FIG. 9, the area whose area unique number is “A4” (that is, area A4) includes four sensor nodes 701. In this example, if the upper limit X of the number of IP packets is “3” or less, the center facility 104 executes the process of FIG. 10 with the area A4 as the target area.

  FIG. 11 is a flowchart showing selection and processing method of a sensor node that starts processing, which is executed by the center facility 104 according to the embodiment of this invention.

  First, the center facility 104 checks whether there is a sensor node to be processed (step 1101). For example, the center facility 104 searches a processing request list on the center side and creates a processing list (not shown). The process list includes, for example, information indicating a unique number of each sensor node, a process status (unprocessed, OK, or NG), a process content, and the number of failures. The center facility 104 determines whether or not there is a sensor node to be processed by searching the processing list. If there is no sensor node to be processed, the center facility 104 waits for a certain period of time (step 1102) and searches again (step 1103).

  When there is a node to be processed, the center facility 104 extracts an area having the lowest division level (refers to the area level number 212 in the division area position management table 201) (step 1104). Next, the center facility 104 extracts an area having the largest number of sensor nodes from the areas extracted in Step 1104 (Step 1105). At this time, the number 215 of sensor nodes in the area in the divided area position management table 201 is referred to.

  Next, the center facility 104 determines whether or not a plurality of areas have been extracted in Step 1105 (Step 1106). When a plurality of areas are extracted, the center facility 104 sequentially executes steps 1107 and 1108. On the other hand, when only one area is extracted, the center facility 104 executes step 1108 without executing step 1107 with the extracted one area as the selected area.

  In step 1107, the center facility 104 selects an arbitrary area (for example, the earliest registration order in the divided area position management table 201) from the plurality of extracted areas. Next, in step 1108, the center facility 104 selects an arbitrary sensor node in the selected area (for example, the registration order of the sensor node position management table 301 is the earliest).

  Next, the center facility 104 performs a process on the selected sensor node and determines a process result (step 1109). The processing executed here is, for example, a request transmitted to the sensor node 103 selected by the center facility 104 via the mobile network 105, and a response (for example, including data acquired by the sensor) from the sensor node 103. It may be a process of receiving. The same applies to the following description. The processing result is determined to be OK if there is a normal response from the sensor node, and determined to be NG if there is no response from the sensor node or if there is an abnormal response. These determination results are reflected in the status of the process list. The same applies to determination results described later.

  If the result is OK, the center facility 104 updates the information related to the selected sensor node (for example, the processing result 316 and response time 317 of the sensor node position management table 301) (step 1110), and then performs the processing shown in FIG. Run. In the case of NG, the center facility 104 performs a request retransmission process (step 1111). If the result of the retransmission process is also NG, the center facility 104 repeatedly executes the retransmission process. If all the results of the specified number of retransmission processes are NG (step 1112), the processing result of the selected sensor node is determined to be NG. Then, the processing result 316 of the sensor node is updated to “NG” (step 1113). Then, the center facility 104 repeats the processing after step 1101 except for the sensor node determined to be NG.

  FIG. 12 is a first part of a first flowchart illustrating the selection and processing method of the sensor node to be processed next, which is executed by the center facility 104 according to the embodiment of this invention.

  Specifically, FIG. 12 shows a flow of selection and processing method of a sensor node to be processed next when a sensor node in any area is processed.

  First, the center facility 104 extracts the level 1 area to which the previously processed sensor node belongs and the unique number of the level 1 area adjacent to the area (step 1201). Here, the sensor node processed last time is the sensor node that starts the process (that is, the sensor node that is processed first) in which the current process of FIG. 12 and the series of processes that follow are selected and processed by the process of FIG. ) Is executed to select a sensor node to be processed next, it is a sensor node selected and processed by the process of FIG. 11 and selected by the previous FIG. 12 and a series of subsequent processes. When executed to select a sensor node to be processed next to the sensor node, the sensor node is selected and processed by the previous processing of FIG. The area to which the sensor node processed last time belongs is also described as the area processed last time.

  For example, in the example of FIG. 7, when the sensor node j was processed last time, in step 1201, the area J to which the sensor node j belongs, and the area E adjacent to the area J (in other words, bordering the area J), F, G, I, K, M, N and O are extracted.

  Further, the level 1 area to which the previously processed sensor node belongs is a level 1 area including the area when the previously processed sensor node belongs to an area lower than level 1. For example, in the example of FIG. 9, when the sensor node processed last time is sensor node a belonging to area A4 of level 2, the level 1 area to which the sensor node processed last time belongs is level 1 including area A4. Area A.

  Next, the center facility 104 extracts an area having the lowest division level among the areas excluding the area extracted in Step 1201, that is, the area divided most finely (Step 1202).

  Next, the center facility 104 determines whether an unprocessed sensor node exists in the area extracted in step 1202 (step 1203). When there is an unprocessed sensor node, the center facility 104 performs selection and processing of the sensor node from the extracted area (step 1204). Details of step 1204 will be described later with reference to FIG. Thereafter, the processing returns to Step 1201, and the center facility 104 performs selection and processing of the sensor node next to the sensor node selected and processed in Step 1204.

  When there is no unprocessed sensor node in the area extracted in step 1202, the center facility 104 determines whether or not the level of the area determined in step 1203 is lower than 1 (step 1205). When the level of the area is lower than 1, the center facility 104 extracts and extracts an area that is one level higher than the area level determined in the previous step 1203 from the area excluding the area extracted in step 1201. The processing after step 1203 is executed for the designated area. For example, if the level 3 area is extracted in step 1202 and it is determined in the next step 1203 that there is no unprocessed node, the center facility 104 uses the area extracted in step 1201. It is determined whether or not there is an unprocessed node in the level 2 area to be excluded (step 1203).

  If it is determined in step 1205 that the level of the area is 1 (that is, the highest level), there is no unprocessed sensor node other than the area extracted in step 1201. In this case, the center facility 104 executes the process shown in FIG. This process will be described later.

  FIG. 13 is a second part of the first flowchart illustrating the selection and processing method of the sensor node to be processed next, which is executed by the center facility 104 according to the embodiment of this invention.

  The process of FIG. 13 is executed in step 1204 of FIG. Furthermore, the processing in FIG. 13 is also executed in step 1405 in FIG. 14 and step 1505 in FIG.

  First, the center facility 104 extracts an area with many unprocessed sensor nodes to which it belongs from the area extracted in step 1202 (step 1301). Next, when a plurality of areas are extracted in step 1301, the center facility 104 extracts, based on the latitude / longitude information, an area having the longest distance from the previously processed area (step 1302). ). The distance between the areas is calculated from, for example, latitude and longitude information at the northwest end of the area.

  Next, the center facility 104 determines whether or not a plurality of areas have been extracted in step 1302 (step 1303). When a plurality of areas are extracted, the center facility 104 selects an arbitrary area (for example, the earliest registration order in the divided area position management table 201) from these areas (step 1304), and proceeds to step 1305. . On the other hand, if only one area is extracted in step 1302, the center facility 104 proceeds to step 1305 with that one area as the selected area.

  Next, the center facility 104 selects an arbitrary one (for example, the one with the earliest registration order in the sensor node position management table 301) from the unprocessed sensor nodes belonging to the selected area (step 1305).

  Thereafter, the center facility 104 executes processing for the selected sensor node, determines the processing result (step 1306), and executes retransmission processing when the determination result is NG (step 1307), and retransmits the specified number of times. If all the processing results are NG (step 1308), the processing result of the selected sensor node is determined to be NG, and the processing result 316 of the sensor node is set to “NG” (step 1310). These processes are the same as steps 1109 and 1111 to 1113 in FIG. On the other hand, if the processing result of step 1306 or the result of the retransmission processing of step 1307 is OK, the processing result 316 of the sensor node is set to “OK” (step 1309). As a result, the sensor node has been processed.

  Next, the center facility 104 updates the divided area position management table 201 and the sensor node position management table 301 based on the above processing result (step 1311). The processing in FIG. 13 is completed as described above, and then the processing after step 1204 in FIG. 12, step 1405 in FIG. 14 or step 1505 in FIG. 15A is executed.

  FIG. 14 is a second flowchart illustrating the selection and processing method of the sensor node to be processed next, which is executed by the center facility 104 according to the embodiment of this invention.

  Specifically, FIG. 14 shows the following when the number of unprocessed sensor nodes belonging to an area other than the level 1 area processed last time and the level 1 area adjacent thereto is 0. Fig. 9 shows processing executed to select and process a sensor node to be processed.

  First, the center facility 104 extracts the lowest level (ie, most finely divided) area other than the previously processed level 1 area (step 1401). At this point, since there is no unprocessed sensor node in the area outside the level 1 area that has already been processed last time and the level 1 area adjacent thereto, in step 1401, the area is adjacent to the level 1 area that was processed last time. The lowest level area included in the level 1 area is extracted.

  Next, the center facility 104 determines whether or not there is an unprocessed sensor node in the area extracted in step 1401 (step 1402). If there is an unprocessed sensor node, sensor node selection and processing are executed for the area extracted in step 1401 (step 1405). This process is as described with reference to FIG. When step 1405 ends, the process returns to step 1401.

  If there is no unprocessed sensor node in the area extracted in step 1401, the center facility 104 determines whether or not the level of the area targeted for determination in step 1402 is 1 (step 1403). When the level of the area targeted for the determination in step 1402 is lower than 1, the center facility 104 targets the area one level higher than the level of the area targeted for the determination in step 1402 as in step 1401. The area is extracted by performing the above process (step 1404). For example, if it is determined in step 1402 that there is no unprocessed sensor node in the level 3 area, the level 2 area is extracted in step 1404. Then, the center facility 104 executes the processing after step 1402 for the area extracted in step 1404.

  If it is determined in step 1403 that the level of the area to be determined in step 1402 is 1, there is no unprocessed sensor node outside the previously processed level 1 area. In this case, the center facility 104 executes the processes of FIGS. 15A and 15B.

  FIG. 15A and FIG. 15B are third flowcharts showing the selection and processing method of the sensor node to be processed next, which is executed by the center facility 104 according to the embodiment of this invention.

  The process shown in FIGS. 15A and 15B is executed when there is no unprocessed sensor node outside the previously processed level 1 area. Even in this case, in order to perform processing as dispersedly as possible within the previously processed level 1 area, areas where sensor nodes that can be processed exist from the upper level are extracted and distributed processing is performed.

  At the time of executing this processing, there is one level 1 area to be processed (that is, the level 1 area processed last time). Hereinafter, this area is also referred to as a corresponding area. First, the center facility 104 determines whether or not there is an area of level 2 or lower in the area (step 1501). If there is no area of level 2 or lower, the center facility 104 processes any sensor node in the area until there is no unprocessed sensor node, and then ends the process.

  Specifically, the center facility 104 determines whether or not there is an unprocessed sensor node in the corresponding area (step 1510), and if there is, selects any unprocessed sensor node for processing. Is executed (step 1511), and the processing result is determined (step 1512). When the processing result is NG, the center facility 104 executes a retransmission process (step 1513), and when the designated number of retransmission processes fails (step 1514), the processing result is set to “NG” (step 1515). . On the other hand, when the processing result is “OK”, the center facility 104 updates the divided area position management table 201 and the sensor node position management table 301. These processes are the same as steps 1109 to 1113 in FIG.

  If it is determined in step 1510 that there are no unprocessed nodes in the corresponding area, the processing for all sensor nodes in the service area ends.

  When it is determined in step 1501 that there is an area of level 2 or lower, the center facility 104 first extracts the level 2 area, and when there are further level 3 and level 4 areas, the center facility 104 extracts the lower level area. Nodes belonging to are extracted, and processing is performed for areas with a large number of nodes. The processing procedure will be described below.

  First, the center facility 104 sets area level 2 as an initial value of the excluded area level (step 1502).

  Next, the center facility 104 extracts an area of the lowest level from areas other than the area of the excluded area level to which the previously processed sensor node belongs (step 1503). This extraction is performed based on the area level number 212 of the divided area position management table 201.

  Next, the center facility 104 determines whether or not there is an unprocessed sensor node in the area extracted in step 1503 (step 1504). If there is an unprocessed sensor node, sensor node selection and processing are executed for the area extracted in step 1503 (step 1505). This process is as described with reference to FIG. When step 1505 ends, the process returns to step 1503. Steps 1503 to 1505 are repeated until it is determined in step 1504 that there is no unprocessed sensor node in the area extracted in step 1503 (all areas when a plurality of areas are extracted).

  If it is determined in step 1504 that there is no unprocessed sensor node in the area extracted in step 1503, the center facility 104 compares the level of the area extracted in step 1503 with the excluded area level (step 1506). When the level of the area extracted in step 1503 is lower than the excluded area level, the center facility 104 determines the level of the area extracted in step 1503 among the areas other than the excluded area level to which the previously processed sensor node belongs. An area one level higher than that is extracted (step 1508), and the processing from step 1504 is executed on the extracted area.

  On the other hand, if the level of the area extracted in step 1503 is the same as the excluded area level, there is a possibility that an unprocessed sensor node remains in an area outside the area of the excluded area level to which the previously processed sensor node belongs. There is no. In this case, the center facility 104 determines whether or not there is an unprocessed node in the area of the excluded area level to which the previously processed sensor node belongs (step 1507). If there is an unprocessed node, the center facility 104 lowers the excluded area level by one level (for example, if the excluded area level is “2”, set it to “3”) (step 1509), The processing after step 1503 is executed.

  If it is determined in step 1507 that there is no unprocessed node, the processing for all sensor nodes in the service area is completed.

  When the above process ends, the status of each sensor node included in the process list (not shown) is either “OK” or “NG”. Similarly, the processing result 316 of each sensor node in the sensor node position management table 301 is either “OK” or “NG”, and the response time actually measured is entered in the response time 317 corresponding to “OK”.

  After that, when it is time to execute processing for all sensor nodes in the service area again, at least the statuses of all sensor nodes included in the processing list are updated to “unprocessed”, and Processing begins. For example, when the center facility 104 periodically acquires sensor data from all sensor nodes, the timing for periodically executing processing for all sensor nodes comes. At this time, the center facility 104 may execute steps 404 to 407 in FIG. 4 again for all sensor nodes in the service area, but based on the value of the response time 317, the processing in step 408 (FIG. 16). And FIG. 17) may be executed.

  FIG. 16 is an explanatory diagram illustrating a distribution of response times acquired by the center facility 104 according to the embodiment of this invention.

  The center facility 104 distinguishes the sensor nodes into a group with a fast response and a group with a slow response from the distribution of the response time 317 values of all the sensor nodes that have been successfully processed. For example, when the distribution 1601 is obtained, the center facility 104 classifies sensor nodes whose response time 317 is equal to or less than the value corresponding to −σ as a group with a fast response time and the rest as a group with a slow response time. Good. This distribution graph is not changed until the position information of the sensor node is reviewed.

  FIG. 17 is a flowchart showing a processing method based on response time, which is executed by the center facility 104 according to the embodiment of this invention.

  First, the center facility 104 creates a distribution (for example, distribution 1601 in FIG. 16) using the response time of each sensor node (step 1701). Next, the center facility 104 determines whether the processing result of each sensor node is OK or NG (step 1702). The sensor node whose processing result is OK is classified into a group having a fast response time or a group having a slow response time based on a comparison result between the response time and the distribution pattern (step 1703). Specifically, for example, a sensor node whose response time value is −σ or less is classified into a group with a fast response time, and the others are classified into a group with a slow response time.

  The center equipment 104 determines that the corresponding base station has a margin for the sensor nodes classified into the group having a fast response time, and continuously (that is, distributes the processing within a range not exceeding the upper limit number of packets X). Perform request transmission processing (in any order) to the target sensor nodes without consideration. Specifically, the center facility 104 can perform arbitrary processing for each sensor node classified into a group with a fast response time, in a range not exceeding the upper limit number of packets X, without considering processing dispersion. Send a request.

  Thereafter, the center facility 104 updates the processing result 316 and the response time 317 of the sensor node position management table 301 according to the processing result of Step 1704 (Step 1705).

  On the other hand, the center facility 104 executes the processes shown in FIGS. 11 to 15B for the sensor nodes classified into the group with the slow response time and the sensor nodes whose processing result is determined to be NG in Step 1702.

  When both of the processing shown in Step 1705 and FIGS. 11 to 15B are finished, the center facility 104 determines whether or not to finish the processing (Step 1706). When the process is not terminated, the center facility 104 executes the processes after step 1702 again. When the process is terminated, step 409 in FIG. 4 is subsequently executed.

  FIG. 18 is an explanatory diagram of adjacent areas in the embodiment of the present invention.

  In the present embodiment, the adjacent area 1802 of the area 1801 processed last time is defined as an area around the area 1801 processed last time, more specifically, an area that borders the area 1801 processed last time. In the example of FIG. 18, eight areas that touch the boundary in the north, northeast, east, southeast, south, southwest, west, and northwest directions of the previously processed area 1801 are adjacent areas 1802.

  FIG. 19 is an explanatory diagram of an adjacent area search method according to the embodiment of this invention.

  The adjacent area 1802 of the highest-level area 1801 including the sensor node processed last time is searched by searching the search target coordinates using the latitude and longitude (northwest end) 213 of the area 1801 as reference coordinates. Specifically, the center facility 104 determines whether or not there is an area in the divided area position management table 201 that matches the area registered in the table of FIG.

  FIG. 20 is an explanatory diagram of an adjacent area search information table that is referred to when the center facility 104 according to the embodiment of this invention searches for an adjacent area.

  An adjacent area search information table 2001 shown in FIG. 20 is held in the storage device 111 of the center facility 104. FIG. 20 shows an adjacent area search information table 2001 related to an area 1801 in which the latitude and longitude at the northwestern end are “xxxx” and “yyyy”, respectively. Specifically, the adjacent area search information table 2001 includes a direction 2011, a latitude 2012, and a longitude 2013.

  For example, “east side”, “xxxx”, and “yyy + (coordinates moved to the east by √10 km)” are held as the direction 2011, latitude 2012, and longitude 2013 of the first entry, respectively. This indicates that the latitude and longitude of the (northwest end) of the area 1802 adjacent to the east side of the area 1801 are “xxxx” and “yyy + (coordinates moved to the east by √10 km)”, respectively.

  Similarly, in the adjacent area search information table 2001, the latitude and longitude of the northwest end of the area 1802 adjacent to the west, south, north, northeast, southeast, northwest and southwest directions of the area 1801 are the adjacent area search information table 2001. Retained. By searching the divided area position management table 201 using these values as keys, adjacent meshes can be searched.

  FIG. 21 is a flowchart showing a process of extracting the adjacent area by the center facility 104 according to the embodiment of this invention.

  Specifically, FIG. 21 illustrates a method for extracting a level 1 area adjacent to a level 1 area including a previously processed sensor node and a lower level area included therein.

  First, the center facility 104 retrieves the coordinates of the northwestern end of the area of level 1 including the previously processed sensor node (step 2101), and in the east-west north-south, northeast, southeast, northwest, and southwest according to the table of FIG. The north-west end coordinates of the adjacent level 1 8 areas are calculated (step 2102). Next, the center facility 104 determines whether or not there is an area having the northwest end coordinates of the adjacent area (step 2103). If there is, the center facility 104 determines that the area is an adjacent area and assigns the unique number to the adjacent area. Registration as an area (step 2104). On the other hand, if there is no area having the northwest end coordinates of the adjacent area, step 2104 is not executed and the process proceeds to step 2105.

  Next, the center facility 104 determines whether or not the search for the eight adjacent areas has been completed (step 2105). If not, the process returns to step 2103 and is repeated until it is finished. When the search for the eight adjacent areas is completed, the center facility 104 determines that the level 1 area including the previously processed sensor node, the level 1 area adjacent to the area, and the level 2 or lower area included in the area. The unique number is extracted (step 2106). The unique number of the lower level area included in the adjacent area of level 1 is obtained by searching for an entry in the divided area position management table having the highest unique number 217 identical to the unique number of the adjacent area of level 1. It is done.

  Hereinafter, a specific example of the order of area selection by the above processing will be described.

  FIG. 22 is a specific example of areas divided in the embodiment of the present invention and the number of sensor nodes distributed in each area.

More specifically, FIG. 22 shows an example of a result of executing Steps 401 to 403 in FIG. In this example, 25 areas delimited by thick solid lines are level 1 (that is, the highest level) areas, and A to Y displayed at the lower left of each are the unique numbers (identifiers) of the respective areas. is there. However, the display of the unique number of the level 1 area is omitted for areas further divided into areas of level 2 or lower. In this example, each level 1 area is a square having an area of 10 km ² and the upper direction in the figure is north, but such a division method is an example, and the actual division method is not limited to this.

  In the example of FIG. 22, the areas G, H, I, L, M, Q, S, and X are divided into areas of level 2 or lower. For example, the area G is divided into level 2 areas G1 to G4 divided by thin solid lines in the north-south direction and the east-west direction passing through the center of the area G. An area specific number G1 and the like are displayed at the lower left of each area. However, in this example, the area G4 is further divided into level 3 areas G41 to G44 which are divided by thin dotted lines in the north-south direction and the east-west direction passing through the center of the area G4, so that the display of the unique number G4 is omitted. Yes. Although the display of the unique number G41 and the like of the area of level 3 is also omitted, the northwest, southwest, northeast, and southeast portions of the area G4 are areas G41, G42, G43, and G44. The relationship between the lowest branch numbers 1 to 4 of the areas G41 to G44 and the direction of each area is also applied to other level 3 areas.

  Similarly, the area H is divided into level 2 areas H1 to H4, and the area H4 is further divided into level 3 areas H41 to H44. Area I is divided into level 2 areas I1 to I4, and area I3 is further divided into level 3 areas I31 to I34. The area L is divided into level 2 areas L1 to L4, and the area L4 is further divided into level 3 areas L41 to L44. Area M is divided into level 2 areas M1 to M4, and area M3 is further divided into level 3 areas M31 to M34. The area Q is divided into level 2 areas Q1 to Q4, and the area Q2 is further divided into level 3 areas Q21 to Q24. Area S is divided into level 2 areas S1 to S4, and area S3 is further divided into level 3 areas S31 to S34. Area X is divided into level 2 areas X1 to X4, and area X2 is further divided into level 3 areas X21 to X24.

  The number displayed in the center of each area is the number of unprocessed sensor nodes included in each area. FIG. 22 shows the number of unprocessed sensor nodes before the process is started, that is, the number of all sensor nodes to be processed included in each area. Here, in order to simplify the description, an example will be described in which the processing of steps 404 to 407 in FIG. 4 is executed for all nodes (that is, step 408 is not executed).

  First, a sensor node that starts processing is selected (step 404). In the example of FIG. 22, the area S33 that is the lowest level and includes the most sensor nodes is selected (steps 1104, 1105, and 1107). Then, any one of the five unprocessed sensor nodes included in the area S33 is selected (step 1108), and the process is executed (step 1109). If the processing is successful, the number of unprocessed nodes in the area S33 is updated to “4”.

  Thereafter, the sensor node to be processed next is selected (steps 405 to 407). In the above example, the previously processed level 1 area S to which the sensor node belongs and the area 1 other than the level 1 area M, N, O, R, T, W, X, Y adjacent thereto (that is, the area S) Among the other areas, the areas having the lowest division level (areas G41 to G44, H41 to H44, I31 to I34, L41 to L44, and Q21 to Q24) are extracted. (Steps 1201 and 1202).

  Subsequently, among the extracted areas, the area G41 having the largest number of sensor nodes included and “3” and farthest from the previously processed area S22 is selected (steps 1301 and 1302). Then, any one of the three unprocessed sensor nodes included in the selected area G41 is selected (step 1305), and the process is executed (step 1306). If the processing is successful, the number of unprocessed nodes in the area G41 is updated to “2” (step 1311).

  Thereafter, areas S33, Q21, S33, G41, X23, M33, X24, G43, S33, H44, Q21, I33, L44, X22, M31, X23, M32, X21, and M33 are sequentially selected in the same procedure. Is done. At the time of selecting the area next to the area M33, the areas X21 to X24 of the lowest level 3 among the areas that are not included in any of the area M and the adjacent areas are all the unprocessed nodes. Does not include any. Therefore, among the areas not included in the area M and any of the adjacent areas, the level 2 areas X1, X2, and X4 that are one level above the level 3 are extracted (step 1206). Since the number of unprocessed sensor nodes included in these is “1”, the area X4 farthest from the area M33 is selected among them (step 1302).

  Thereafter, in the same procedure, areas G41, S34, G43, S32, G42, S33, G44, S31, H41, Q23, I32, Q21, I34, Q24, I31, Q22, I33, L43, I2, L41, X3, H42, X1, H43, S4, L42, I4, L44, S2, H44, S1, G3, I1, L3, N, L1, N, G2, N, L2, Y, M31, E, M33, J, M34, D, M32, T, W, O, and R are sequentially selected.

  At the time of selecting the area next to the last area R in the above example, no unprocessed sensor node remains in an area that is not included in any of the area R and adjacent areas. Further, the level of area R is 1. Therefore, next, an area N that is adjacent to the area R and that still has one unprocessed sensor node is selected (steps 1401 to 1404), and an unprocessed sensor node in the area N is processed. (Step 1405). This completes the processing for all the sensor nodes in the service area.

  Here, in order to explain the specific example of FIG. 15A, at a certain point in time, unprocessed sensor nodes as shown in FIG. 22 remain only in area I, and the number of unprocessed sensor nodes in all other areas. Is assumed to be zero. That is, the number of unprocessed sensor nodes of I1, I2, I31, I32, I34, and I4 is “1”, the number of unprocessed sensor nodes of I33 is “2”, and the remaining areas of all other areas are unprocessed. Assume that the number of sensor nodes in the process is “0”.

  In this example, when the area I33 is selected, processing for one of the two sensor nodes in the area I33 is executed, and the number of unprocessed sensor nodes in the area I33 is “1”. The process shown in FIG. 12 is executed in order to select the sensor node to be processed next, but there are no unprocessed sensor nodes remaining in the area that is not included in any of the area I and the adjacent area. Finally, in step 1205, the area level is determined to be “1”, and the process of FIG. 14 is executed. However, as described above, since there are no unprocessed sensor nodes remaining in areas other than area I, it is finally determined in step 1402 that there are no unprocessed nodes, and in step 1403 the area level is “ 1 "and the process of FIG. 15A is executed.

  In the process of FIG. 15A, since an area below level 2 exists in area I, level 2 is set as an excluded level area (steps 1501 and 1502). In areas other than the level 2 area I3 including the sensor node processed last time, the lowest level areas I1, I2 and I4 are extracted (step 1503), and an unprocessed sensor node exists in them (step 1504). ), The area I2 is selected (steps 1301 and 1302), and the process is executed (step 1306). As a result, the number of unprocessed sensor nodes in area I2 is “0”.

  In order to select the sensor node to be processed next, the process of FIG. 15A is executed in the same procedure as described above, and the areas I31 to I34 of the lowest level other than the area I2 of the level 2 including the previously processed sensor node are displayed. It is extracted (step 1503), and finally, the area I33 is selected and processed (steps 1301, 1302, 1306). Thereafter, I1, I34, I4, and I31 are sequentially selected by the same processing.

  In order to select a sensor node to be processed next, the process of FIG. 15A is executed in the same procedure as described above. Areas I1, I2, and I4 are extracted in step 1503. At this point, since there are no unprocessed nodes in areas other than area I32, it is determined in step 1504 that there are no unprocessed nodes. In step 1506, it is determined that the level of the extracted area I1 and the like is “2”, which is the same as the excluded area level, and in step 1507, it is determined that there is an unprocessed node. Then, the excluded area level is set to “3” (step 1509), and the areas I32, I33 and I34 other than the area I31 including the previously processed sensor node are extracted (step 1503). I32 including the node is selected (step 1301), and the process is executed (step 1306).

  Here, the effect of the embodiment of the present invention will be described.

  Conventionally, operators who conduct M2M business cannot finely control a large number of sensor nodes due to the bottleneck of the communication network, and are limited to services based on the method of autonomous call from sensor nodes, or from the center side Only limited processing could be performed, and the service content was limited. However, according to the present embodiment, it becomes possible to create a new value-added service by enabling control from the center side to more sensor nodes than ever before.

  In addition, the carrier network always provides packet communication for ordinary voice calls, smartphones, and the like, and if the M2M network is adapted to the current carrier network as it is, it will place additional load on the heavily loaded base station and communication equipment. . By using this method, the load on the equipment can be measured from the distribution of sensor nodes and the response time of the terminal, and the load on the base station and the communication equipment can be distributed in a pseudo manner.

  Further, by periodically reviewing the sensor node distribution, it is possible to adapt even when the sensor node is a mobile object, and it is possible to cope with the distribution and usage frequency of other users.

  The details of the above effect will be described below in comparison with the embodiment.

  12 and 13, the sensor node belonging to the area outside the level 1 area including the sensor node processed last time and the level 1 area adjacent thereto is selected as the sensor node to be processed next. This is a sensor node whose distance from the previously processed sensor node is at least the size of the area of level 1 (in the example of FIG. 5, FIG. 22, etc., the sensor node that is more than √10 km2 away from the previously processed sensor node) Is preferentially selected as the sensor node to be processed next.

  In general, the exact location of the base station 108 and its coverage area are not known to anyone other than the wireless carrier that provides the mobile network 105. However, when the approximate size of the cover area is estimated and an area equivalent to that size is set as shown in FIG. 5 etc., the two sensor nodes belonging to the two adjacent areas are actually May belong to the coverage area of one base station 108, but two sensor nodes belonging to two areas that are not adjacent to each other are unlikely to belong to the coverage area of one base station 108. Therefore, a request to the sensor node is made by selecting a sensor node belonging to an area outside the level 1 area including the sensor node processed last time and an adjacent level 1 area as a sensor node to be processed next. Continuous transmission from the same base station is prevented. As a result, communication is geographically distributed, and it is possible to prevent the load from being concentrated on a specific base station.

  Furthermore, according to the processes of FIGS. 11 to 13, more finely divided areas are preferentially selected, and areas including more unprocessed sensor nodes are preferentially selected among the areas of the same level. Is done. As a result of the processing of FIGS. 9 and 10, it can be said that the smaller the area is, the higher the density of sensor nodes in the area. Moreover, even if it is an area of the same level, the density of unprocessed sensor nodes is so high that it includes many unprocessed sensor nodes.

  In other words, preferentially selecting a lower level (ie, more finely divided) area is to preferentially select a sensor node in a region where sensor nodes are dense as a sensor node to be processed next. Means. In addition, preferentially selecting sensor nodes in an area that includes more unprocessed sensor nodes gives priority to sensor nodes in areas where the density of unprocessed sensor nodes is high as the next sensor node to be processed. Means to choose.

  If the processing order for sensor nodes is determined without considering the density of sensor nodes, unprocessed sensor nodes may remain concentrated in a narrow area as the processing proceeds. In that case, it becomes difficult to geographically sufficiently distribute the processing for those unprocessed sensor nodes. By determining the processing order in consideration of the density of sensor nodes as described above, it is possible to prevent unprocessed sensor nodes from being concentrated in a small area and to distribute the processing sufficiently geographically until the end. Can do.

  Even if the processing considering the density as described above is performed, unprocessed sensor nodes may remain concentrated in a narrow area, but even in that case, according to the embodiment of the present invention, Processing can be geographically distributed as much as possible. Specifically, unprocessed sensor nodes remain in areas other than the level 1 area adjacent to the level 1 area including the previously processed sensor node, but remain in the adjacent level 1 area. If so, the processing is distributed between the level 1 area including the previously processed sensor node and the adjacent level 1 area (FIG. 14). When multiple unprocessed sensor nodes remain in only one level 1 area, and the level 1 area is divided into lower level areas, processing is distributed among the lower level areas. (FIG. 15A). In these cases, sensor nodes that are as distant as possible are selected (step 1302). If the lower level area and the actual base station coverage area correspond approximately, the above processing increases the possibility that the processing can be geographically distributed.

  In addition, since the area is divided based on the upper limit of the communication amount per unit time (FIG. 10), the communication from the center facility 104 using one base station 108 is performed by the distribution of the processing as described above. Exceeding the upper limit of is prevented.

  For sensor nodes classified into groups with fast response times, there is a high possibility that the corresponding base station has room, so processing can be carried out efficiently by distinguishing them from other sensor nodes. it can.

  In addition, this invention is not limited to above-described embodiment, Various modifications are included. Here, although the typical modification of embodiment of this invention is demonstrated, this invention is not limited to these modifications.

  The sensor node 103 in the above embodiment is an example of a terminal device, and can be replaced by any type of terminal device. Each terminal device may be of any type as long as it can communicate with the center facility 104 via a network, and for example, may not include a sensor. The center facility 104 sequentially transmits requests to the terminal devices in the order determined by the above method, and receives responses from the terminal devices. The response from each terminal device may be of any type as long as it meets the request. For example, sensor data may not be included.

  Although the above embodiment shows an example in which the sensor node 103 performs wireless communication with the base station 108, the sensor node 103 may perform wired communication. In this case, the base station 108 is a relay device that relays wired communication between the sensor node 103 and the center facility 104 or the like. The present invention can be applied if each base station 108 has a cover area (at least an approximate cover area) and the approximate size can be estimated.

  The above embodiment shows an example where the location of each base station 108 is unknown and thus the exact location and size of the coverage area of each base station 108 is unknown, but when they are clear Also, the present invention can be applied. In this case, it is not necessary to divide the area shown in FIG. 5 and the like, and information regarding the actual cover area is registered in the divided area position management table 201. In this case, since there is no need to consider the possibility that the base station is added, it is not necessary to subdivide the area shown in FIG. For example, the processing of the present embodiment may be performed with all the cover areas as level 1 areas regardless of their sizes. Even if the cover area is clear, it may be unclear to which area the sensor node 103 near the boundary belongs. Also in this case, by selecting a sensor node 103 to be processed next to the sensor node 103 processed last time from areas that are not adjacent to the previous area, at least an adjacent area between the two sensor nodes 103 is selected. Therefore, transmission of continuous requests to one base station can be surely avoided.

  Further, in the above embodiment, when a certain sensor node 103 is selected, processing for the sensor node 103 is executed, and after determining the result, the next sensor node 103 is selected (for example, FIG. 12 and FIG. 12). 13). However, such a procedure is an example, and the next sensor node 103 may be selected before the process of the selected sensor node 103 is executed. For example, the center facility 104 may determine the processing order of all the sensor nodes 103 in advance by the method shown in FIGS. 11 to 15B, and then execute the processing for each sensor node 103 in the determined order.

  Further, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to the one having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  Each of the above-described configurations, functions, processing units, processing means, and the like may be realized by hardware by designing a part or all of them with, for example, an integrated circuit. Further, each of the above-described configurations, functions, and the like may be realized by software by interpreting and executing a program that realizes each function by the processor. Information such as programs, tables, and files for realizing each function is stored in a non-volatile semiconductor memory, a hard disk drive, a storage device such as an SSD (Solid State Drive), or a computer-readable non-readable information such as an IC card, SD card, or DVD. It can be stored on a temporary data storage medium.

  In the drawings, control lines and information lines considered necessary for describing the embodiment are shown, and all control lines and information lines included in an actual product to which the present invention is applied are not necessarily shown. Not necessarily. Actually, it may be considered that almost all the components are connected to each other.

DESCRIPTION OF SYMBOLS 101 Communication system 102 GPS satellite 103 Sensor node 104 Center equipment 105 Mobile telecommunications carrier network 106 Divided area (district)
107 Gateway device 108 Base station 109 Service area 110 Processor 111 Storage device 112 Interface 201 Division area position management table 301 Sensor node position management table 501 Service area (area where service is provided by the operator)
502 Position coordinate of center of service area 503 Divided area 701 Sensor node 901 Level 1 area 902 Level 2 area 1301 Distribution graph 1501 of sensor node Adjacent area 1502 Area 1601 to which own sensor node belongs Northwest end of area to which own sensor node belongs Latitude and longitude 1602 Latitude and longitude of the northwestern edge of the adjacent area

Claims (12)

A control method for a communication system, comprising: a network; a plurality of terminals; and a control device connected to the network and communicating with each of the terminals via the network,
The control device includes an interface connected to the network, a processor connected to the interface, and a storage device connected to the processor.
The control method of the communication system is:
The control device and the plurality of terminals so as to preferentially select one terminal that is a predetermined distance or more away from the terminal that performed the previous communication among the plurality of terminals. A first procedure for determining the communication order of
A control method for a communication system, comprising: a second procedure in which the control device communicates with each of the plurality of terminals via the network in the determined order. A control method for a communication system according to claim 1,
In the first procedure, the control device is one terminal located in an area where the density of the terminals is high among the plurality of terminals located at a point more than a predetermined distance from the terminal that performed the previous communication. Including a procedure for preferentially selecting the communication target for the next communication. A control method for a communication system according to claim 2,
The storage device includes area information for identifying a plurality of areas generated by dividing a space including the positions of the plurality of terminals into a predetermined size, and terminal information including the position information of the terminals. Hold and
The plurality of terminals include a first terminal, and the plurality of areas include a first area including the first terminal,
The first procedure includes:
A third procedure in which the control device identifies, based on the area information, one area other than the first area that does not contact the first area;
The control device is included in the specified area based on the area information and the terminal information as a terminal that performs communication after communication with the first terminal. And a fourth procedure for specifying one of the terminals. A control method for a communication system according to claim 3,
In the third procedure, the control device includes a largest number of the terminals that are not yet in communication among the first area and an area that is not in contact with the first area. A control method for a communication system, comprising a procedure for specifying an area. A control method for a communication system according to claim 3,
The control method of the communication system further includes a procedure of further dividing an area including the terminal exceeding a predetermined number among the plurality of areas into a plurality of areas,
The third procedure includes a procedure in which the control device specifies one area that is most finely divided among the first area and an area that is not in contact with the first area. A control method for a communication system characterized by the above. A control method for a communication system according to claim 5,
The network includes a plurality of radio base stations that perform radio communication with the plurality of terminals,
The control method for a communication system, wherein the predetermined number is the number of packets that the base stations can communicate per unit time. A control method for a communication system according to claim 1,
The control device acquires a response time of communication with each terminal,
A procedure in which the control device classifies the plurality of terminals into a first group in which the response time is smaller than a predetermined value and a second group other than the first group;
The control device further includes, in any order, communicating with each of the plurality of terminals classified into the first group via the network,
The communication system control method, wherein the first procedure and the second procedure are performed on a plurality of terminals classified in the second group. A control method for a communication system according to claim 1,
The network includes a plurality of radio base stations that perform radio communication with the plurality of terminals,
Each of the terminals is a sensor node having a communication unit that performs wireless communication with any one of the wireless base stations, and a sensor.
Communication between the control device and each terminal in the second procedure includes transmission of a request from the control device to the terminals, transmission of a response from the terminals to the control device in response to the request, Including
The method of controlling a communication system, wherein the response includes data acquired by the sensor. A communication system comprising a network, a plurality of terminals, and a control device connected to the network and communicating with each terminal via the network,
The controller is
An interface connected to the network; a processor connected to the interface; and a storage device connected to the processor;
Among the plurality of terminals, the order of communication with the plurality of terminals is preferentially selected as a target for the next communication, one terminal that is more than a predetermined distance away from the terminal that performed the previous communication. Decide
A communication system, wherein communication is performed with each of the plurality of terminals via the network in the determined order. The communication system according to claim 9, wherein
The control device selects one terminal located in an area where the density of the terminals is high among the plurality of terminals located at a predetermined distance or more from the terminal that performed the previous communication for the next communication. A communication system, wherein an order of communication with the plurality of terminals is determined so as to be preferentially selected as a target. A control device that communicates with a plurality of terminals via a network,
An interface connected to the network; a processor connected to the interface; and a storage device connected to the processor;
Among the plurality of terminals, the order of communication with the plurality of terminals is preferentially selected as a target for the next communication, one terminal that is more than a predetermined distance away from the terminal that performed the previous communication. Decide
A control apparatus that performs communication with each of the plurality of terminals via the network in the determined order. The control device according to claim 11,
Among the plurality of terminals that are located at a predetermined distance or more away from the terminal that performed the previous communication, one terminal that is located in an area where the density of the terminals is high is given priority as the next communication target. The control apparatus determines the order of communication with the plurality of terminals so as to select.