JP5128196B2 - Ad hoc terminal, ad hoc communication system, and ad hoc communication method - Google Patents

Description

  The present invention relates to an ad hoc terminal, an ad hoc communication system, and an ad hoc communication method.

At work sites where GPS (Global Positioning System) and existing LAN (Local Area Network) cannot be used, a portable terminal owned by the worker and a center that manages the worker are equipped with a plurality of portable relay devices. A worker management communication system, a portable relay device, a portable terminal device, a worker management device, and a communication relay program that are connected via the network are disclosed (for example, see Patent Document 1).
JP 2006-318247 A

In the field work site where heavy machinery and machine tools are used, there are many cases in which wireless communication is easily interrupted due to the influence of topography, weather, etc., and wireless communication becomes impossible.
Also, at such work sites, there are cases where large mobile objects such as trucks and excavators frequently come and go and the communication path is easily interrupted by stopping between wireless terminals. Cheap.

In the technique described in Patent Document 1, the portable relay device (terminal) is arranged at the start of work and is not moved thereafter. And the portable terminal which a worker has communicates with the portable relay apparatus which exists in the nearest distance.
When such a system is applied to an outdoor work site, a situation in which communication between portable relay devices is interrupted easily due to the reasons described above. And patent document 1 has no description about the countermeasure when it becomes such a condition.

  The present invention has been made in view of such a background, and the present invention relates to an ad hoc terminal and an ad hoc communication system capable of establishing a communication path even in a situation where wireless communication between terminals is easily interrupted. It is another object of the present invention to provide an ad hoc communication method.

  In order to solve the above problems, the ad hoc terminal, the ad hoc communication system, and the ad hoc communication method of the present invention determine a communication path based on a relayable value obtained by quantifying the likelihood of the ad hoc terminal to be a relay terminal. It is characterized by that.

  According to the present invention, it is possible to provide an ad hoc terminal, an ad hoc communication system, and an ad hoc communication method capable of establishing a communication path even in a situation where wireless communication between terminals is easily interrupted.

  Next, the best mode for carrying out the present invention (referred to as “embodiment”) will be described in detail with reference to the drawings as appropriate.

(Whole system)
FIG. 1 is a diagram illustrating a configuration example of an ad hoc communication system according to the present embodiment.
The ad hoc communication system 1 includes a plurality of ad hoc terminals 2.
The ad hoc terminal 2 is a terminal used for ad hoc communication. By establishing a communication path between the ad hoc terminals 2, the ad hoc terminal 2 that is the transmission source terminal 6 transfers to the ad hoc terminal 2 that is the final destination terminal 7. Perform data communication.
The ad hoc terminal 2 includes a fixed terminal 3 (3A to 3D) and a mobile terminal 4 (4A, 4B). The fixed terminal 3 is a terminal fixed at a specific location. For example, if the fixed terminal 3 is installed by a worker at the start of work, the fixed terminal 3 is not moved until the work is finished.
As will be described later, the mobile terminal 4 basically has the same structure as the fixed terminal 3, but can be easily moved by being mounted on a mobile body such as a truck or an excavator.

In the example illustrated in FIG. 1, an example in which fixed terminals 3 </ b> A to 3 </ b> D are installed between the transmission source terminal 6 and the final transmission destination terminal 7 at the start of work. It is assumed that a communication failure occurs between the fixed terminal 3B and the fixed terminal 3C, and communication between the fixed terminal 3B and the fixed terminal 3C is interrupted. Communication failures may be natural conditions such as topography or weather, or artificial conditions due to truck stops.
In the ad hoc communication system 1 according to the present embodiment, when the situation shown in FIG. 1 occurs, the mobile terminal 4 is selected as a relay terminal. In the example shown in FIG. 1, the mobile terminal 4B mounted on the shovel car is selected from the mobile terminals 4A and 4B, and the communication path indicated by the solid line arrow in FIG. 1 is established. The selection process of the mobile terminal 4 will be described with reference to FIGS.

In the ad hoc communication system 1 described in the present embodiment, the side close to the transmission source terminal 6 is “upstream”, and the side close to the final transmission destination terminal 7 is “downstream”.
Further, as will be described later, an arbitrary ad hoc terminal 2 may transmit communication information to all terminals that can be adjacent terminals on the downstream side. In such a case, the ad hoc terminal 2 that can be an adjacent terminal on the downstream side with respect to the target ad hoc terminal 2 is described as a “downstream terminal”.
For example, in FIG. 1, the downstream terminals of the fixed terminal 3B are the fixed terminal 3C and the mobile terminals 4A and 4B.
In addition, regarding an arbitrary terminal, an upstream adjacent terminal from which data is transmitted is referred to as an upstream terminal. For example, in FIG. 1, the upstream terminal of the fixed terminal 3B is the fixed terminal 3A.

In the present embodiment, information to be transmitted from the transmission source terminal 6 to the final transmission source terminal 7 by ad hoc communication is described as data, and is temporarily transmitted and received between the ad hoc terminals 2 for establishing a communication path. It will be distinguished from information. That is, in the present embodiment, data is video information at a work site or information indicating a work situation.
Data and information temporarily transmitted / received between the ad hoc terminals 2 for establishing a communication path are collectively referred to as communication information.

[First embodiment: radio wave intensity method]
Next, as a first embodiment, a radio wave intensity method for selecting the mobile terminal 4 based on the radio wave intensity will be described with reference to FIGS. 2 to 4.

FIG. 2 is a diagram illustrating a configuration example of the ad hoc terminal according to the first embodiment.
The ad hoc terminal 2a includes a communication unit 21, a processing unit 22a, a radio wave intensity measurement unit 23, and a storage unit 24a. The communication unit 21, the processing unit 22a, the radio wave intensity measurement unit 23, and the storage unit 24a are connected to each other.
The communication unit 21 is connected to an antenna and has a function of receiving and transmitting various communication information.
The processing unit 22a has a function of performing various processes, and includes a path selection unit 221 that determines a communication path based on the radio wave intensity measured by the radio wave intensity measurement unit 23.
The radio wave intensity measurement unit 23 has a function of measuring the intensity of radio waves received by the communication unit 21.
The storage unit 24a has a function of storing various kinds of information. The routing table 241 is a list of IP (Internet Protocol) addresses of networks to which the ad hoc terminal 2a itself is wirelessly connected, and the ad hoc terminal 2a itself transmits the information. A transmission history 242 for storing the processed data as a history is stored. The storage unit 24a also has a function of temporarily storing information necessary for establishing a communication path.
The ad hoc terminal 2a has the same configuration, not limited to the fixed terminal 3 and the mobile terminal 4, but the transmission history 242 may be omitted when the routing table method described in FIG. The routing table 241 may be omitted when the broadcast method described later with reference to FIG. 4 is used.

(First embodiment: Routing table method)
Next, processing when the first embodiment is applied to routing table communication will be described with reference to FIG. Note that all the flowcharts described in this specification are processing for a packet of the same data group (that is, one original data, and when all the original data is transmitted, settings regarding the transmission destination and the like are reset. .

FIG. 3 is a flowchart showing a flow of processing of the routing table method according to the first embodiment.
First, the communication unit 21 of the ad hoc terminal 2a (terminal) that has received data (information) transmitted from an upstream terminal sends the received data to the processing unit 22a, and the processing unit 22a It memorize | stores in the memory | storage part 24a.
Next, the communication unit 21 of the ad hoc terminal 2a transmits a communication confirmation request to each downstream terminal according to the routing table 241 at intervals of 2 seconds, for example (S102).
When the communication unit 21 of each downstream terminal receives this communication confirmation request (S103), the processing unit 22a of each downstream terminal acquires its own address from an address management unit (not shown).
Subsequently, the processing unit 22a of each downstream terminal causes the communication unit 21 to transmit a communication confirmation response (communication information) with this address added as a header to the terminal (S104).

After the communication unit 21 of the ad hoc terminal 2a transmits a communication confirmation request in step S102, the processing unit 22a monitors whether or not a predetermined time has elapsed using a timer (not shown) (S105).
As a result of step S105, when the predetermined time has not elapsed (S105 → No), the communication unit 21 waits for a communication confirmation response transmitted from the downstream terminal.
When the communication unit 21 of the ad hoc terminal 2a receives a communication confirmation response from the downstream terminal (S106), the radio wave intensity measurement unit 23 measures the radio field intensity of the received communication confirmation response (S107).
Then, the route selection unit 221 determines whether or not the measured radio wave intensity indicates a value equal to or greater than a preset threshold value (S108).
As a result of step S108, when the radio wave intensity is not equal to or greater than the threshold value (S108 → No), the processing unit 22a returns to the process of step S105. That is, the processing unit 22a deletes the communication confirmation response whose radio wave intensity is less than the threshold value, and does not establish a communication path with the downstream terminal that has transmitted the communication confirmation response.
If the result of step S108 is that the radio wave intensity is equal to or greater than the threshold value (S108 → Yes), the processing unit 22a stores the address and radio wave intensity added to the received communication confirmation response header as pair information. The data is stored in the unit 24a (S109), and the processing unit 22a returns to the process of step S105.

Returning to the description of step S105.
When a predetermined time has elapsed after transmitting the communication confirmation request in step S102 (S105 → Yes), the route selection unit 221 refers to the storage unit 24a, and the address stored together with the radio wave intensity in step S109 is It is determined whether or not it exists (S110).
As a result of step S110, when the address stored together with the radio wave intensity does not exist (S110 → No), the processing unit 22a returns to the process of step S101.
As a result of step S110, when there is an address stored together with the radio wave intensity (S110 → Yes), the route selection unit 221 includes the address stored in the storage unit 24a in the previous step S116 among the stored addresses ( It is determined whether or not the previous transmission destination exists (S111).
As a result of step S111, when the previous transmission destination does not exist in the stored address (S111 → No), the route selection unit 221 selects the address having the maximum radio wave intensity among the stored addresses as the transmission destination. (S112), and the processing unit 22a proceeds to the process of step S114.
If the previous transmission destination exists in the stored address as a result of step S111 (S111 → Yes), the path selection unit 221 sets the previous transmission destination as the address (transmission destination) of the current transmission destination. (S113). The reason why the previous transmission destination is the current transmission destination in step S113 is that frequent change of the communication path is not desirable, and it is desirable to use the established communication path as much as possible.

Next, when the processing unit 22a acquires data from the storage unit 24a, the processing unit 22a transmits the data to the transmission destination set in step S112 or step S113 (S114).
Then, the processing unit 22a updates the routing table 241 such as adding the destination address set in step S112 or step S113 to the routing table 241 (S115). Subsequently, the processing unit 22a stores the transmission destination address set in step S112 or step S113 in the storage unit 24a (S116), and the processing unit 22a returns to the processing of step S101.

For example, in the system shown in FIG. 1, since the truck on which the mobile terminal 4A is mounted is located far from the fixed terminal 3B, the communication confirmation response transmitted from the mobile terminal 4A to the fixed terminal 3B is small. Assume that the signal strength is indicated. And since the shovel car in which the mobile terminal 4B is mounted exists in a place close to the fixed terminal 3B, the communication confirmation response transmitted from the mobile terminal 4A to the fixed terminal 3B shows a large radio wave intensity. Shall.
When a communication failure as shown in FIG. 1 occurs, the fixed terminal 3B compares the radio wave intensities of the communication confirmation responses transmitted from the mobile terminal 4A and the mobile terminal 4B, and sends a communication confirmation response with a high radio wave intensity. By selecting the transmitted mobile terminal 4B as a transmission destination (communication target terminal), the mobile terminal 4B is selected as a relay terminal.

(First embodiment: broadcast method)
Next, a process when the first embodiment is applied to broadcast communication will be described along FIG. 4 with reference to FIG.
FIG. 4 is a flowchart showing a flow of processing of the broadcast method according to the first embodiment.
First, the communication unit 21 receives data broadcast from an arbitrary upstream terminal (S201).
Next, the radio wave intensity measuring unit 23 measures the radio wave intensity of the received data (S202).
Then, the route selection unit 221 determines whether or not the measured radio wave intensity is a value equal to or greater than a preset threshold value (S203).
As a result of step S203, when the radio wave intensity is not equal to or greater than the threshold value (S203 → No), the processing unit 22a deletes the received data and returns to the process of step S201.

As a result of step S203, when the radio wave intensity is equal to or greater than the threshold value (S203 → Yes), the processing unit 22a refers to the transmission history 242 of the storage unit 24a, and the transmitted data having the same content is transmitted to the transmission history 242. (S204).
If there is data having the same contents as a result of step S204 (S204 → Yes), the processing unit 22a considers that the data has already been transmitted, and does not transmit the data to the downstream terminal. Return to processing.
If there is no data having the same contents as a result of step S204 (S204 → No), the processing unit 22a regards the data as untransmitted data and directs the data to all the adjacent ad hoc terminals 2 to the communication unit 21. Broadcast transmission (S205).
Then, the processing unit 22a updates the transmission history 242 by storing the content of the data transmitted in step S205 in the transmission history 242 of the storage unit 24a (S206), and the processing unit 22a proceeds to the process of step S201. Return.

  When a communication failure as shown in FIG. 1 occurs, the fixed terminal 3C surrounds data whose radio wave intensity of data sequentially transmitted from the mobile terminal 4A and the mobile terminal 4B is equal to or higher than a threshold and whose reception time is early. Are sequentially transmitted to all the ad hoc terminals 2. When the radio field intensity of the data transmitted from the mobile terminal 4A is less than the threshold value and the radio field intensity of the data transmitted from the mobile terminal 4B is equal to or greater than the threshold value, the fixed terminal 3C is transmitted from the mobile terminal 4A. The data transmitted from the mobile terminal 4B is transmitted to the surrounding ad hoc terminals 2 without transmitting data. Thereby, the mobile terminal 4B is selected as a communication relay terminal.

  In the first embodiment, as illustrated in FIG. 1, the description is made on the assumption that the fixed terminal 3 and the mobile terminal 4 are mixed. The ad hoc communication system 1 may be configured. That is, for example, the mobile terminals 4A and 4B may be replaced with the fixed terminal 3, respectively.

(Effect of 1st Embodiment)
According to the first embodiment, even if a communication failure occurs on a communication path, the ad hoc terminal 2 itself selects another ad hoc terminal 2 that has transmitted communication information with high radio field strength as a relay terminal, Communication paths with other ad hoc terminals 2 can be easily established.

[Second Embodiment: Willingness Method]
Next, as a second embodiment, referring to FIG. 5 to FIG. 9, a Willingness method for selecting a mobile terminal 4 based on a Willingness value (terminal state value) obtained by quantifying the likelihood of being a relay terminal. I will explain.

FIG. 5 is a diagram illustrating a configuration example of an ad hoc terminal according to the second embodiment.
In FIG. 5, the same components as those in FIG.
The ad hoc terminal 2b in FIG. 5 is different from the ad hoc terminal 2a shown in FIG. 2 in the following points.
The first point is that the processing unit 22b includes a Willingness value setting unit 222 that sets a Willingness value based on the state of the ad hoc terminal 2b. A method for setting the Willingness value will be described later with reference to FIGS. 6 and 7.
The second point is that the storage unit 24b has a Willingness value setting table 243 that is a table for setting Willingness values.
The third point is that the sensor information acquisition unit 25 that acquires various sensor information necessary for setting the Willingness value from the control unit 100 installed outside the ad hoc terminal 2b includes the processing unit 22b and the storage unit 24b. It is a point formed by connecting to. Note that the control unit 100 may be a part of the ad hoc terminal 2b.
The fourth point is that the radio wave intensity measuring unit 23 (see FIG. 2) is omitted.

Here, the Willingness value is a numerical value of the likelihood of the ad hoc terminal 2b becoming a relay terminal, and a numerical value of the state of the ad hoc terminal 2b. Basically, when the ad hoc terminal 2b is mounted on a mobile body such as a construction machine, it is considered that the mobile terminal is likely to become a relay terminal if the mobile body is in a stopped state or a state estimated to be stopped. The terminal 2b sets a large value for the Willingness value. On the other hand, if the vehicle is traveling or is estimated to be traveling, it is considered difficult to become a relay terminal, and the ad hoc terminal 2b sets the Willingness value to a small value.
Willingness value setting conditions include vehicle speed, gate lock ON / OFF (from gate lock switch), crane mode ON / OFF (from crane mode switch), GPS (Global Positioning System) position data, front excavation The load, the pump load (from the pump load sensor), the oil temperature (from the oil temperature sensor), the water temperature (from the water temperature sensor), the remaining amount of fuel (from the fuel tank sensor), etc. can be considered. These pieces of sensor information are collected by the control unit 100 and then acquired by the sensor information acquisition unit 25 as shown in FIG.
The relationship between these setting conditions and the Willingness value will be described later with reference to FIG.

When the ad hoc terminal 2b is the fixed terminal 3, the control unit 100 and the sensor information acquisition unit 25 may be omitted.
Further, when the routing table method described later in FIG. 8 is used, the transmission history 242 may be omitted, and when the broadcast method described later in FIG. 9 is used, the routing table 241 may be omitted.

(Willingness value setting table)
FIG. 6 is a diagram illustrating an example of a Willingness value setting table.
Here, an example is shown in which the vehicle speed is used as the setting condition for the Willingness value.
Note that the Willingness value in this specification is considered to be likely to be a relay terminal if the value is large, and to be difficult to be a relay terminal if the value is small.
As shown in FIG. 6, a large Willingness value is set if the speed of a vehicle (such as a truck or an excavator) on which the ad hoc terminal 2b is mounted is low, and a small Willingness value is set if the speed is fast.
As described above, the setting condition is not limited to the vehicle speed. For example, if the gate lock or the crane mode (whether or not the excavator is used) is ON, the vehicle is considered to be stopped. If a large Willingness value is set and turned OFF, a small Willingness value may be set assuming that there is a possibility of moving.

Further, if there is no change in the GPS position data, a large Willingness value may be set, and if there is a change, a small Willingness value may be set.
Furthermore, if the excavation load on the front part and the pump load are large, the vehicle can be considered to be working and stopped. Therefore, if a large Willingness value is set and these loads are small, the vehicle is small. A Willingness value may be set.
Also, if the oil temperature, water temperature is high, or the amount of remaining fuel is low, even if you are currently driving, it is considered that there is a possibility of stopping in the near future, and even if you set a large Willingness value Good.

(Willingness value setting process)
Here, the Willingness value setting process will be described with reference to FIG.
FIG. 7 is a flowchart showing the flow of the Willingness value setting process.
The process shown in FIG. 7 is performed every minute, for example.
First, the sensor information acquisition unit 25 acquires sensor information corresponding to the setting condition of the Willingness value from the control unit 100 (S301).
Next, the Willingness value setting unit 222 acquires sensor information from the sensor information acquisition unit 25, and based on this sensor information (for example, vehicle speed in the example of FIG. 6), the Willingness value setting table 243 shown in FIG. In step S302, the Willingness value is set. The processing unit 22b stores the set Willingness value in the storage unit 24b.
In the fixed terminal 3, the Willingness value may be set to the maximum ("6" in the example of FIG. 6) from the beginning.

(Second embodiment: routing table method)
Next, processing when the second embodiment is applied to routing table type communication will be described along FIG. 8 with reference to FIG.

FIG. 8 is a flowchart illustrating a processing flow of the routing table method according to the second embodiment.
First, the communication unit 21 of the ad hoc terminal 2b (terminal) that has received the data transmitted from the upstream terminal sends the received data to the processing unit 22b, and the processing unit 22b stores the sent data in the storage unit 24b. Remember me.
Next, the communication unit 21 of the ad hoc terminal 2b transmits a communication confirmation request to each downstream terminal according to the routing table 241, for example, at intervals of 2 seconds (S402).
When the communication unit 21 of each downstream terminal receives this communication confirmation request (S403), the processing unit 22b of each downstream terminal acquires the Willingness value set from the storage unit 24b (S404), and Obtains its own address from an address management unit (not shown).
Next, the processing unit 22b adds the acquired Willingness value to the header of the communication confirmation response (S405), and further adds its own address to the header.
Subsequently, the processing unit 22b of each downstream terminal causes the communication unit 21 to transmit a communication confirmation response with the Willingness value and its own address added as a header to the terminal (S406).

After the communication unit 21 of the ad hoc terminal 2b transmits a communication confirmation request in step S402, the processing unit 22b monitors whether or not a predetermined time has elapsed using a timer (not shown) or the like (S407).
As a result of step S407, when the predetermined time has not elapsed (S407 → No), the communication unit 21 waits for a communication confirmation response transmitted from the downstream terminal.
When the communication unit 21 of the ad hoc terminal 2b receives the communication confirmation response from the downstream terminal (S408), the processing unit 22b receives the address added to the header of the communication confirmation response and the Willingness value. The data are sequentially stored in the storage unit 24b (S409). Then, the processing unit 22b returns to the process of step S407. In step S409, for example, it is stored in a list format with list numbers assigned in the order of reception.

Returning to the description of step S407.
If a predetermined time has elapsed after transmitting the communication confirmation request in step S402 (S407 → Yes), the route selection unit 221 refers to the storage unit 24b and determines whether the address stored in step S409 exists. Is determined (S410).
As a result of step S410, when the address stored with the Willingness value does not exist (S410 → No), the processing unit 22b returns to the process of step S401.
As a result of step S410, when there is an address stored with the Willingness value (S410 → Yes), the route selection unit 221 compares the stored Willingness value, and whether there is only one address with the largest Willingness value. Is determined (S411).
As a result of step S411, when there is not only one address with the largest Willingness value (S411 → No), the route selection unit 221 selects the address with the earliest reception time among the addresses with the largest Willingness value. The transmission destination address (transmission destination) is set (S412), and the processing unit 22b proceeds to the process of step S414. Specifically, in step S409, when the address and Willingness value are stored in a list format, an address having the largest Willingness value and a small list number is selected.

  As a result of step S411, when there is only one address with the largest Willingness value (S411 → Yes), the route selection unit 221 uses the address (address with the largest Willingness value) as the destination address (destination). (S413).

Next, the processing unit 22b transmits data to the transmission destination set in step S412 or step S413 (S414).
Then, the processing unit 22b updates the routing table 241 such as adding the destination address set in step S412 or step S413 to the routing table 241 (S415). Subsequently, the processing unit 22b stores the transmission destination address set in step S412 or step S413 in the storage unit 24b (S416), and the processing unit 22b returns to the process of step S401.

  When a communication failure as shown in FIG. 1 occurs, the fixed terminal 3B compares the Willingness value included in the communication confirmation response from the mobile terminal 4A and the mobile terminal 4B. Assuming that the truck equipped with the mobile terminal 4A is traveling and the excavator car equipped with the mobile terminal 4B is stopped and working, as described with reference to FIGS. 6 and 7, the mobile terminal 4B The Willingness value is set to a value larger than the Willingness value of the mobile terminal 4A. Therefore, by selecting the mobile terminal 4B that has transmitted the communication confirmation response including the large Willingness value as the transmission destination, the mobile terminal 4B is selected as the relay terminal.

(Second embodiment: broadcast method)
Next, processing when the second embodiment is applied to broadcast communication will be described along FIG. 9 with reference to FIG.
FIG. 9 is a flowchart showing a flow of processing of the broadcast method according to the second embodiment.
First, the route selection unit 221 acquires the Willingness value set for itself from the storage unit 24b (S501).
Then, the route selection unit 221 determines whether or not the acquired Willingness value is equal to or greater than a preset threshold value (S502).
If the Willingness value is not equal to or greater than the preset threshold value as a result of Step S502 (S502 → No), the processing unit 22b deletes the received data and returns to the processing of Step S501. That is, when the Willingness value set for itself is less than the threshold, data from the upstream terminal is not received. Thereby, the ad hoc terminal 2b removes itself from the communication path in advance.

As a result of step S502, when the Willingness value is equal to or greater than a preset threshold value (S502 → Yes), the communication unit 21 waits for data reception.
Then, when the communication unit 21 receives data (S503), the processing unit 22b refers to the transmission history 242 of the storage unit 24b and determines whether or not transmitted data having the same content exists in the transmission history 242. Is determined (S504).
If there is data having the same contents as a result of step S504 (S504 → Yes), the processing unit 22b assumes that the data has already been transmitted, and transmits the data to the downstream terminal without transmitting the data to step S501. Return to processing.
If there is no data having the same contents as a result of step S504 (S504 → No), the processing unit 22b regards the data as untransmitted data and directs the data to all the adjacent ad hoc terminals 2 to the communication unit 21. Broadcast transmission (S505).
Then, the processing unit 22b updates the transmission history 242 by storing the content of the data transmitted in step S505 in the transmission history 242 of the storage unit 24b (S506), and the processing unit 22b proceeds to the process of step S501. Return.

For example, when a communication failure as shown in FIG. 1 occurs, the mobile terminal 4A and the mobile terminal 4B first determine whether or not the Willingness value set in the mobile terminal 4A is equal to or greater than a threshold value. Since the truck on which the mobile terminal 4A is mounted is running, when the Willingness value of the mobile terminal 4A is less than the threshold, the mobile terminal 4A does not receive data. Therefore, the mobile terminal 4A is excluded from the relay terminal candidates.
Since the excavator equipped with the mobile terminal 4B is stopped and working, when the Willingness value of the mobile terminal 4B is equal to or greater than the threshold, the mobile terminal 4B receives the data transmitted from the upstream terminal. Then, data is transmitted to all surrounding ad hoc terminals 2.
Therefore, a communication path using the mobile terminal 4B as a relay terminal is established.

(Effect of 2nd Embodiment)
According to the second embodiment, by setting the Willingness value, which is the ease of becoming a relay terminal considering the state of the ad hoc terminal 2, the priority order of the relay terminals is set based on the state of the ad hoc terminal 2. be able to. Thereby, based on the Willingness value, it is possible to search for an ad hoc terminal 2 in an environment where stable communication is performed, and a stable communication path can be easily established even if a communication failure occurs.

[Third Embodiment: Mode Priority Method]
Next, as a third embodiment, with reference to FIG. 10 to FIG. 14, a description will be given regarding a radio wave intensity priority mode or a Willingness priority mode (collectively referred to as mode priority method).

FIG. 10 is a diagram illustrating a configuration example of an ad hoc terminal according to the third embodiment.
10, the same components as those in FIGS. 2 and 5 are denoted by the same reference numerals, and the description thereof is omitted.
The ad hoc terminal 2c in FIG. 10 is different from the ad hoc terminal 2b shown in FIG. 5 in the following points.
The first point is that the radio wave intensity measuring unit 23 described in FIG. 2 is added.
Also, the second point is whether the processing unit 22c performs the radio wave intensity priority mode processing described later or the Willingness priority mode processing based on information input via an input unit (not shown), for example. This is a point having a mode selection unit 223 for setting.

Similarly to FIG. 5, when the ad hoc terminal 2 c is the fixed terminal 3, the control unit 100 and the sensor information acquisition unit 25 may be omitted.
Further, when the routing table priority mode described later in FIGS. 11 and 12 is used, the transmission history 242 may be omitted. When the broadcast priority mode described later in FIGS. 13 and 14 is used, the routing table 241 is changed. It may be omitted.

(Third embodiment: field strength priority mode: routing table method)
Next, a process when the radio wave intensity priority mode of the third embodiment is applied to the routing table method will be described along FIG. 11 with reference to FIG.
FIG. 11 is a flowchart showing a flow of processing in the radio wave intensity priority mode (routing table method) according to the third embodiment.
It should be noted that whether to perform the radio wave strength priority mode processing shown in FIG. 11 or the Willingness priority mode processing described later in FIG. 12 (mode selection) is selected by the user from an input unit (not shown). Is input, and the mode is selected by the mode selection unit 223 based on the input selection information.
In FIG. 11, the same processes as those in FIG. 3 are denoted by the same reference numerals and description thereof is omitted.

First, the process in step S601 in FIG. 11 is a summary of the processes in steps S403 to S406 in FIG.
If the result of step S108 is that the radio field intensity is equal to or greater than the threshold value (S108 → Yes), the processing unit 22c measures the address and Willingness value added to the corresponding communication confirmation response, and step S107. The received signal strength is stored in the storage unit 24b in the order of reception as pair information (S602), and the processing unit 22c returns to the process of step S105.
As a result of step S108, when the radio field intensity is not equal to or greater than the threshold value (S108 → No), the processing unit 22c stores the address added to the communication confirmation response and the Willingness value as pair information in the storage unit 24b in the order of reception. Store (S603), and the processing unit 22c returns the process to step S105. That is, in step S603, the radio wave intensity is not stored in the storage unit 24b.
In step S602 and step S603, for example, they are stored in a list format with list numbers assigned in the order of reception.

Furthermore, when the address stored together with the radio field intensity does not exist as a result of step S110 (S110 → No), the route selection unit 221 selects the address with the earliest reception time among the addresses having the largest Willingness value. Address (destination) is set (S604). Here, the specific processing content of step S604 is the same as the processing of steps S411 to S413 in FIG.
As a result of step S110, when there is an address stored together with the radio field intensity (S110 → Yes), the route selection unit 221 selects the address with the maximum radio field intensity among the stored addresses (transmission destination). ) Is set (S605).

  For example, when a communication failure as shown in FIG. 1 occurs, the fixed terminal 3B receives communication confirmation responses from the mobile terminal 4A, the mobile terminal 4B, and a plurality of ad hoc terminals 2 (not shown). Since the truck is working away from the fixed terminal 3B, it is assumed that the radio wave intensity of the communication confirmation response sent from the mobile terminal 4A to the fixed terminal 3B is small and is less than the threshold in step S108. . On the other hand, since the excavator is traveling near the fixed terminal 3B, the radio wave intensity of the communication confirmation response sent from the mobile terminal 4B to the fixed terminal 3B is a large value, which is equal to or greater than the threshold value in step S108. It is assumed that Similarly, it is assumed that the radio wave intensity of the communication confirmation response from the ad hoc terminal 2 other than the mobile terminal 4A and the mobile terminal 4B is equal to or greater than the threshold value in step S108. In such a case, the fixed terminal 3B first removes the mobile terminal 4A from the candidate relay terminals. Then, the fixed terminal 3B stores the Willingness value of each ad hoc terminal 2 that has not been excluded from the relay terminal candidates and the corresponding address as a pair of information.

  Next, the fixed terminal 3B compares the Willingness value included in the communication confirmation response from each ad hoc terminal 2 that is not excluded from the relay terminal candidates, and corresponds to the largest Willingness value with the earliest reception time. Get the address to be used. Here, it is assumed that the Willingness value corresponding to the mobile terminal 4B satisfies the condition. Accordingly, the mobile terminal 3B determines the mobile terminal 4B as the data transmission destination.

(Third embodiment: Willingness priority mode: routing table method)
Next, the processing when the Willingness priority mode of the third embodiment is applied to the routing table method will be described along FIG. 12 with reference to FIG.
FIG. 12 is a flowchart showing the flow of processing in the Willingness priority mode (routing table method) according to the third embodiment.
In FIG. 12, the same processing as in FIG.
In FIG. 12, the process of step S603 in FIG. 11 is omitted, and the process of step S110 in FIG. 11 is replaced with the process of step S701. In step S701, the route selection unit 221 is replaced with a determination (S701) as to whether or not there is an address having a Willingness value greater than or equal to a preset threshold value among the plurality of addresses stored in step S602. It is that you are.
As a result of step S701, when there is a communication confirmation response corresponding to the Willingness value equal to or greater than the threshold (S701 → Yes), the route selection unit 221 performs the process of step S604 in FIG.
As a result of step S701, when there is no communication confirmation response corresponding to the Willingness value equal to or greater than the threshold (S701 → No), the route selection unit 221 performs the process of step S605 in FIG.

For example, when a communication failure as shown in FIG. 1 occurs, the fixed terminal 3B compares the radio field intensities of communication confirmation responses from the mobile terminal 4A and the mobile terminal 4B. Here, for example, it is assumed that the truck on which the mobile terminal 4A is mounted is traveling, and that the excavator car on which the mobile terminal 4B is mounted is stopped and working. In this case, the Willingness value of the mobile terminal 4A is a small value, and the Willingness value of the mobile terminal 4B is a large value.
Since the truck equipped with the mobile terminal 4A and the excavator equipped with the mobile terminal 4B are present near the fixed terminal 3B, the intensity of radio waves transmitted from the mobile terminals 4A and 4B is Both of them exceed a preset threshold value.

The fixed terminal 3B removes the ad hoc terminal 2c that has sent the communication confirmation response having the radio wave intensity equal to or lower than the threshold value in step S108 of FIG. 12 from the candidate relay terminals. In this example, it is assumed that neither the mobile terminal 4A nor the mobile terminal 4B has been excluded from the relay terminal candidates in step S108.
The Willingness value attached to the communication confirmation response sent from the mobile terminal 4A is less than the threshold value in step S701 in FIG. 12, and is attached to the communication confirmation response sent from the mobile terminal 4B. It is assumed that the Willingness value has a value equal to or greater than the threshold value. As a result, in step S701 in FIG. 12, the mobile terminal 4B is selected as a relay terminal candidate, and the mobile terminal 4A is excluded from the relay terminal candidates.
The Willingness value attached to the communication confirmation response sent from the mobile terminal 4A is larger than the Willingness value of the communication confirmation response sent from the ad hoc terminal 2c other than the mobile terminals 4A and 4B, and is earliest by the solid terminal B. If received, the mobile terminal 4B is selected as a relay terminal.

(Third embodiment: radio wave strength priority mode: broadcast method)
Next, a process when the radio wave intensity priority mode of the third embodiment is applied to the broadcast method will be described along FIG. 13 with reference to FIG.
FIG. 13 is a flowchart showing a flow of processing in the radio wave intensity priority mode (broadcast method) according to the third embodiment.
It should be noted that whether to perform the radio wave strength priority mode processing shown in FIG. 13 or the Willingness priority mode processing (to be described later in FIG. 14) is selected by the user from a not-shown input unit (mode selection). Is input, and the mode is selected by the mode selection unit 223 based on the input selection information.
In FIG. 13, the same processes as those in FIGS. 4 and 9 are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 13, when the radio wave strength priority mode in the third embodiment is applied to the broadcast method, the process shown in FIG. 9 is performed between the process of step S203 and the process of step S204 shown in FIG. The processing of S501 and step S502 is inserted.
That is, in step S203, the route selection unit 221 compares the radio wave intensity with a predetermined threshold value to delete data having radio wave intensity that does not satisfy a predetermined value. Further, in step S501, the route selection unit 221 removes itself as a relay terminal candidate if the acquired Willingness value obtained by the processing unit 22c is less than a predetermined threshold value in step S501 (S502 → No). If so, it selects itself as a candidate for the relay terminal (S502 → Yes), and proceeds to the processing after step S204.

For example, in FIG. 1, since the truck equipped with the mobile terminal 4A travels far from the fixed terminal 3C, the radio field intensity of the data received by the fixed terminal 3C from the mobile terminal 4A is a small value. It is assumed that the value does not satisfy the threshold value in step S203. Since the mobile terminal 4B is stopped and working at a location close to the fixed terminal 3C, the radio field intensity of data received by the fixed terminal 3C from the mobile terminal 4B is a high value, and step S203 in FIG. It is assumed that the value satisfies the threshold value.
When a communication failure as shown in FIG. 1 occurs, the fixed terminal 3C first deletes the data transmitted from the mobile terminal 4A in step S203 of FIG. Do not delete. If the Willingness value of the fixed terminal 3C itself is equal to or greater than the threshold value in step S502, the fixed terminal 3C broadcasts the data transmitted from the mobile terminal 4B to all the neighboring ad hoc terminals 2. In this way, the mobile terminal 4B is selected as a relay terminal.
If the Willingness value of the fixed terminal 3C itself is less than the threshold value in step S502, the fixed terminal 3C does not broadcast data.

(Third embodiment: Willingness priority mode: broadcast method)
Next, the processing when the Willingness priority mode of the third embodiment is applied to the broadcast method will be described along FIG. 14 with reference to FIG.
FIG. 14 is a flowchart showing a processing flow of the broadcast method (Willingness priority mode) according to the third embodiment.
Further, in FIG. 14, the same processes as those in FIGS. 4 and 9 are denoted by the same reference numerals and description thereof is omitted.

As shown in FIG. 14, the processing when the Willingness priority mode in the third embodiment is applied to the broadcast method is performed before the processing of step S201 shown in FIG.
The process of step S501 and step S502 shown in FIG. 9 is performed.
That is, in step S502, when the Willingness value of the ad hoc terminal 2c itself is less than the threshold value (S502 → No), it removes itself from the relay terminal candidates without sending data to the downstream terminal.
In step S502, when the Willingness value of the ad hoc terminal 2c itself is equal to or greater than the threshold (S502 → Yes), the ad hoc terminal 2c performs the processes of steps S201 to S206 in FIG.

For example, in FIG. 1, since the mobile terminal 4A is traveling far away from the fixed terminal 3C, the radio field intensity of the data received from the mobile terminal 4A by the fixed terminal 3C is a small value, and in step S203 of FIG. It is assumed that the value does not satisfy the threshold. Since the mobile terminal 4B is stopped and working at a location close to the fixed terminal 3C, the radio field intensity of the data received by the fixed terminal 3C from the mobile terminal 4B is a high value, and step S203 in FIG. It is assumed that the value satisfies the threshold value.
When a communication failure as shown in FIG. 1 occurs, first, the fixed terminal 3C compares its Willingness value with a threshold (S502 in FIG. 14), and whether or not the fixed terminal 3C itself can be a relay terminal. Determine. If the fixed terminal C itself cannot be a relay terminal, the fixed terminal C removes itself from the candidate relay terminal and does not receive data sent from the upstream terminal.

  When the solid terminal C itself can be a relay terminal, the radio field intensity of data transmitted from the mobile terminal 4A and the mobile terminal 4B is compared with a threshold value in the order of transmission, and has a radio field intensity greater than the threshold value in step S203 in FIG. The data of the mobile terminal 4B is broadcasted sequentially to all surrounding ad hoc terminals 2. Then, the data transmitted from the mobile terminal 4A is deleted without being transmitted to the surrounding ad hoc terminals 2 by the fixed terminal 3C. Thereby, the mobile terminal 4B is selected as a relay terminal, and the mobile terminal 4A is excluded from the candidates for the relay terminal.

(Effect of the third embodiment)
According to the third embodiment, since the communication path is established by using both the path selection based on the radio wave intensity and the path selection based on Willingness, a more stable communication path is established than in the first embodiment and the second embodiment. It becomes possible.

[Fourth Embodiment: Mode Switching Method by Number of Relays]
Next, as a fourth embodiment, a mode switching method based on the number of relays will be described with reference to FIGS. 15 to 17.

FIG. 15 is a diagram illustrating a configuration example of an ad hoc terminal according to the fourth embodiment.
15, the same components as those in FIG. 10 are denoted by the same reference numerals, and the description thereof is omitted.
The ad hoc terminal 2d in FIG. 15 is different from the ad hoc terminal 2c shown in FIG. 10 in the following points.
That is, the processing unit 22d adds 1 to the number of hops added to the header of the transmitted data, etc., thereby counting the number of hops, and the information transmission speed in the ad hoc terminal 2d. And a DBR (Data Bit Rate) / N calculation unit 225 for calculating. “N” in DBR / N is a variable indicating the number of hops.

Here, the hop count is the number of relay terminals relayed in the ad hoc communication path. For example, taking the communication path (solid arrow) in FIG. 1 as an example, the number of hops in the fixed terminal 3A is “1”, and the number of hops in the fixed terminal 3B is “2”. The number of hops in the mobile terminal 4B is “3”, and the numbers of hops of the fixed terminals 3C and D are “4” and “5”, respectively.
DBR is a transmission rate when communication is performed between the terminals when there are only two terminals on the communication path.
The DBR is a value that can be arbitrarily set by the user, but is preferably about half of the maximum transmission rate of the wireless LAN (Local Area Network) being used. For example, if a wireless LAN having a maximum transmission rate of 11 Mbps (Bit Per Second) is used in the ad hoc communication system 1 (see FIG. 1), it is desirable to set the DBR to 5.5 Mbps. The set DBR is stored in the storage unit 24b.

(Fourth embodiment: Routing table method)
Next, processing when the mode switching method based on the number of relays according to the fourth embodiment is applied to the routing table method will be described with reference to FIG.
FIG. 16 is a flowchart showing a flow of communication processing by the routing table method according to the fourth embodiment.
In FIG. 16, the same processes as those in FIG.
In FIG. 16, it is assumed that the Willingness priority mode is selected by the mode selection unit 223 before the processing starts. When the radio wave strength priority mode is prioritized, the processing in FIG. 11 is performed.

First, the communication unit 21 receives data in step S801, and the number of hops and the bit rate in the communication path are added to the header of this data. The processing unit 22d stores the received data in the storage unit 24b.
Next, after the processing unit 22d acquires the number of hops attached to the received data and attaches it to the header of the communication confirmation request, the communication unit 21 of the ad hoc terminal 2d attaches the number of hops at intervals of 2 seconds, for example. The received communication confirmation request is transmitted to each downstream terminal according to the routing table 241 (S802).

  The downstream terminal that has received the communication confirmation request adds the number of hops and transmits a communication confirmation response (S803). Specifically, after step S403 and step S404 in FIG. 8 are performed, the hop count counting unit 224 of the downstream terminal acquires the hop count attached to the communication confirmation request, and adds 1 to this hop count. . Then, the processing unit 22d adds the Willingness value, the number of hops, and its own address to the header of the communication confirmation response, and transmits the communication confirmation response to the terminal.

As a result of step S105, if the fixed time has not elapsed since the transmission of the communication confirmation request, the result of the determination by the processing unit 22d (S105 → No), the ad hoc terminal 2d performs a communication confirmation response reception process (S804). . Step S804 summarizes the processing from step S106 to step S602 in FIG.
Next, the DBR / N calculation unit 225 acquires the DBR set in advance from the storage unit 24b (S805), and acquires the hop count added to the received communication confirmation response, the DBR / N value is obtained. Calculate (S806). Here, N is the number of hops.
Then, the processing unit 22d stores the calculated DBR / N in the storage unit 24b as the address, the radio wave intensity and the Willingness value stored in the storage unit 24b in step S804, and the set information (S807).

As a result of step S105, if it is determined that a certain time has elapsed after the transmission of the communication confirmation request (S105 → Yes), the mode selection unit 223 acquires the bit rate from the header of the data received in step S801. Then, it is determined whether or not there is an address where DBR / N is less than the bit rate (S808).
When there is an address where DBR / N is less than the bit rate (S808 → Yes), the mode selection unit 223 switches to the radio wave intensity priority mode of the third embodiment (S809). Specifically, the processing of steps S110 to S605 in FIG. 11 is performed.
As a result of step S808, when there is no address where DBR / N is less than the bit rate (S808 → No), the processing unit 22d proceeds to the process of step S604.
When transmitting data in step S114, the processing unit 22d adds the hop count and bit rate stored in the storage unit 24b together with the address set in step S604 to the data header, and then transmits the data. .

(Fourth embodiment: broadcast system)
Next, a process when the mode switching method based on the number of relays according to the fourth embodiment is applied to the broadcast method will be described with reference to FIG.
FIG. 17 is a flowchart showing a flow of communication processing by the broadcast method according to the fourth embodiment.
In FIG. 16, the same processes as those in FIG. 14 are denoted by the same reference numerals, and the description thereof is omitted.
In FIG. 17, it is assumed that the Willingness priority mode is selected by the mode selection unit 223 before the processing starts. When the radio wave strength priority mode is prioritized, the processing in FIG. 11 is performed.

First, the communication unit 21 receives data from the upstream terminal (S901), and the radio wave intensity measurement unit 23 measures the radio wave intensity of the received data (not shown). The number of hops and bit rate are added to the header of the received data.
Next, the hop count counting unit 224 acquires the hop count added to the data header, and the hop count counting unit 224 adds 1 to this hop count (S902).
Next, the DBR / N calculation unit 225 acquires a preset DBR from the storage unit 24b (S903), and calculates the value of DBR / N (S904). Here, N is the number of hops.

Next, the mode selection unit 223 acquires the bit rate from the header of the data received in step S901, and determines whether DBR / N is less than the bit rate (S905).
When there is an address where DBR / N is less than the bit rate (S905 → Yes), the mode selection unit 223 switches to the radio wave intensity priority mode of the third embodiment shown in FIG. 13 (S906). Specifically, the processing in steps S203 to S206 in FIG. 13 is performed.
As a result of step S905, when there is no address where DBR / N is less than the bit rate (S905 → No), the process proceeds to step S501. That is, processing in Willingness priority mode is performed.
When data is broadcast to downstream terminals, the bit rate and the number of hops calculated by the hop number counting unit 224 are added to the data header and then broadcast.

  In step S808 in FIG. 16 and step S905 in FIG. 17, the mode selection unit 223 determines whether or not the calculated DBR / N is less than the bit rate. The switching condition to the radio wave strength priority mode may be arbitrarily set, for example, when DBR / N is 1 Mbps or more lower than the bit rate added to the header.

(Effect of 4th Embodiment)
The radio wave intensity method (radio wave intensity priority mode) tends to cause frequent route changes, but can reduce the number of relays. The Willingness method (Willingness priority mode) has a high possibility that the number of relays is increased, but the occurrence of a route change is small and a stable communication route can be established. Since the transmission rate in the communication path is inversely proportional to the number of hops, an unlimited increase in the number of hops is undesirable.
Therefore, by monitoring DBR / N for each ad hoc terminal 2d, when the number of relays (hops) is large (DBR / N becomes a low value), the number of relays can be reduced from the Willingness priority mode. Switch to signal strength priority mode. Thus, when the number of hops is small, the Willingness priority mode that can establish a stable communication path is used, and when the number of hops increases, the radio wave strength priority mode that can reduce the number of relays can be used. Accordingly, an appropriate mode can be selected.

  16 and 17, the process of switching from the Willingness priority mode to the radio wave intensity priority mode has been described, but the process of switching from the radio wave intensity priority mode to the Willingness priority mode may be performed.

For example, the process of step S804 in FIG. 16 is the process of steps S106 to S603 in FIG. 11, and the process of step S808 is the mode selection unit 223 whether there is an address satisfying DBR / N ≧ bit rate. It is processing to determine whether or not. When there is no address satisfying DBR / N ≧ bit rate, the mode selection unit 223 switches to the Willingness priority mode of the third embodiment.
When there is an address satisfying DBR / N ≧ bit rate, the processing unit 22d performs the processing in steps S110 to S605 in FIG. 11 instead of step S604 in FIG. Processing to switch from the priority mode to the Willingness priority mode can be performed.

  In FIG. 17, in step S906, the mode selection unit 223 determines whether DBR / N ≧ bit rate, and if DBR / N ≧ bit rate, the mode selection unit 223 determines that the third embodiment. Switch to Willingness priority mode. If DBR / N ≧ bit rate is not satisfied, the processing unit 22d performs step S203 in FIG. 17 and then executes step S501 and step S502, so that the radio field strength priority mode in the broadcast method is set. Processing to switch to the Willingness priority mode can be performed.

[Fifth embodiment: communication path formation by number of sessions]
Next, as a fifth embodiment, with reference to FIG. 18 and FIG. 19, a description will be given regarding processing for forming a communication path by the number of sessions.

FIG. 18 is a diagram illustrating a configuration example of an ad hoc terminal according to the fifth embodiment.
18, the same components as those in FIG. 5 are denoted by the same reference numerals, and the description thereof is omitted.
The ad hoc terminal 2e in FIG. 18 is different from the ad hoc terminal 2b shown in FIG. 5 in the following points.
The first point is that the processing unit 22e includes a route formation method switching unit 226 that selects a communication route (route) formation method based on the Willingness value.
The second point is that the storage unit 24e has a route formation setting table 244 referred to by the route formation method switching unit 226. The route formation setting table 244 will be described later with reference to FIG.

When the ad hoc terminal 2e is the fixed terminal 3, the control unit 100 and the sensor information acquisition unit 25 may be omitted.
Further, when the routing table method is used in step S1006 of FIG. 20 described later, the transmission history 242 may be omitted, and when the broadcast method is used, the routing table 241 may be omitted.

FIG. 19 is a diagram illustrating an example of a route formation setting table according to the fifth embodiment, and FIG. 20 is a diagram illustrating an example of a communication route.
The route formation setting table 244 shown in FIG. 19 associates the number of sessions with the Willingness value, and further stores the mode selected according to the Willingness value.
Here, the number of sessions is the number of communication paths formed in one ad hoc terminal 2e.

Here, the number of sessions will be described with reference to FIG.
FIG. 20 is a diagram illustrating an example of an ad hoc communication system 1 ′ formed by any one of the first to fourth embodiments.
In FIG. 20, reference numerals 3 </ b> E to 3 </ b> I indicate the fixed terminal 3, and reference numerals 4 </ b> C and 4 </ b> D indicate the mobile terminal 4. Reference numerals 1001 to 1003 denote communication paths. The ad hoc terminal 2 ′ indicates any one of the ad hoc terminals described in the first to fourth embodiments.
As shown in FIG. 20, in the ad hoc communication system 1 ′, the mobile terminals 4C and 4D approach the place where the communication path 1002 passing through the fixed terminals 3E to 3I is formed, and a new communication path 1001 (fixed terminal 3E) is formed. → mobile terminal 4C → fixed terminal 3G → fixed terminal 3H → fixed terminal 3I) and communication path 1003 (fixed terminal 3E → mobile terminal 4D → fixed terminal 3G → fixed terminal 3H → fixed terminal 3I) are formed.

At this time, the number of sessions of the fixed terminals 3E, 3G to 3I is “3”, and the number of sessions of the fixed terminal 3F and the mobile terminals 4C, 4D is “1”.
At this time, the burden on the fixed terminals 3E, 3G to 3I is obviously large, and the burden on the fixed terminal 3F and the mobile terminals 4C, 4D is small. In particular, the fixed terminal 3E transmits communication information to the fixed terminal 3F and the mobile terminals 4C and 4D. In general, the burden on the terminal that transmits communication information to the mobile terminal 4 (see FIG. 1) is greater than the transmission of communication information to the fixed terminal 3 (see FIG. 1), so the burden is concentrated on the fixed terminal 3E. I understand.

Here, as shown in FIG. 19, an ad hoc terminal with a large number of sessions decreases the Willingness value to make it difficult to become a relay terminal, and an ad hoc terminal 2 with a small number of sessions increases the Willingness value to increase the relay terminal. Make it easier to become.
When the number of sessions is equal to or greater than a predetermined value (in the example of FIG. 19, the number of sessions is “4” or more), the radio wave strength priority mode or Willingness priority mode is canceled to reduce the number of ad hoc terminals to which a load is applied. A general communication route is formed. Here, the formation of a general communication path is a method of selecting a path with a small number of hops.

Next, the processing of the fifth embodiment will be described along FIG. 21 with reference to FIG.
FIG. 21 is a diagram illustrating a process flow of the mode selection method according to the fifth embodiment.
The processing unit 22e of the ad hoc terminal 2e constantly monitors the number of sessions established on itself (S1001).
Then, the communication unit 21 monitors whether data has been received (S1002).
While the communication unit 21 is not receiving data (S1002 → No), the processing unit 22e repeats steps S1001 to S1002.
When the communication unit 21 receives the data (S1002 → Yes), the route formation method switching unit 226 obtains the number of sessions from the processing unit 22e, and refers to the route formation setting table 244 in the storage unit 24e to set the number of sessions. A corresponding Willingness value is acquired (S1003).
Next, the route formation method switching unit 226 determines whether or not the acquired Willingness value is a value equal to or greater than a predetermined threshold (“4” in the example of FIG. 19) (S1004).
As a result of step S1004, when the acquired Willingness value is not equal to or greater than the threshold value (S1004 → No), a general communication route (communication route) for selecting a route with a small number of hops is formed (S1005). Since the process in step S1004 is a process generally performed in ad hoc communication or the like, description thereof is omitted.
As a result of the determination in step S1004, if the Willingness value is equal to or greater than the threshold (S1004 → Yes), the radio field strength priority process or the fixed terminal 3 priority process is performed according to a predetermined mode setting (S1006). The process of step S1006 may be any of the processes described in the first to fourth embodiments. However, the processing performed in step S1006 is processing after “data reception” in FIGS.
Then, the terminal enters a reception standby state, and the process returns to step S1101.

(Effect of 5th Embodiment)
Next, an example of a communication path formed by the fifth embodiment will be described along FIG. 22 with reference to FIG.
FIG. 22 is a diagram illustrating an example of communication paths formed according to the fifth embodiment.
In FIG. 22, for simplification of explanation, if the number of sessions is two or more, the radio wave strength priority mode or the Willingness priority mode is selected, and if the number of sessions is less than two, a general communication path is formed. Shall be performed.
In FIG. 20, the fixed terminal 3F having the number of sessions of “1” is set to a small Willingness value, so is likely to be a relay terminal, and the fixed terminals 3E and 3G to 3I are set to have a large Willingness value. It becomes difficult to become a relay terminal.
Therefore, the mobile terminal 4C that has first approached the ad hoc communication system 1 ′ has a 3F with a small Willingness value and a communication path 1001 ′ (fixed terminal 3E → mobile terminal 4C → fixed terminal 3F → fixed terminal 3G → fixed terminal 3H → fixed. Terminal 3I) is formed. Thus, the fixed terminals 3E to 3I all have the number of sessions “2”.

  Next, when the mobile terminal 4D that has approached the ad hoc communication system 1 ′ forms a communication path, the fixed terminals 3E to 3I all have the number of sessions “2”, so select a communication path with a small number of hops. A general communication path is formed. Accordingly, the mobile terminal 4D forms a communication path 1003 '(fixed terminal 3E → mobile terminal 4D → fixed terminal 3H → fixed terminal 3I) with a small number of hops.

  Thus, by changing the Willingness value depending on the number of sessions, a communication path that reduces the burden on the ad hoc terminal 2e can be formed.

(Overall effect)
In the first to fifth embodiments, the field strength of communication information received by the ad hoc terminal 2 or the Willingness value obtained by quantifying the state of the ad hoc terminal 2 itself is set as a relayable value, and based on the field strength or Willingness value. The relay terminal communication (communication target terminal) in the network is selected. Thereby, the ad hoc terminal 2 which can become a relay terminal is searched, and communication can be established. Therefore, a communication path can be easily established even in an environment where communication between ad hoc terminals 2 is easily interrupted.

  The processing units 22a to 22e and the units 221 to 226 constituting the processing units 22a to 22e shown in FIGS. 2, 5, 10, 15 and 18 are not shown in ROM (Read Only Memory) or not shown. A program stored in a storage device such as an HD (Hard Disk) is developed in a RAM (Random Access Memory) (not shown) and executed by a CPU (Central Processing Unit) (not shown).

It is a figure which shows the structural example of the ad hoc communication system which concerns on this embodiment. It is a figure which shows the structural example of the ad hoc terminal which concerns on 1st Embodiment. It is a flowchart which shows the flow of the process of the routing table system which concerns on 1st Embodiment. It is a flowchart which shows the flow of the process of the broadcast system which concerns on 1st Embodiment. It is a figure which shows the structural example of the ad hoc terminal which concerns on 2nd Embodiment. It is a figure which shows the example of a Willingness value setting table. It is a flowchart which shows the flow of Willingness value setting processing. It is a flowchart which shows the flow of the process of the routing table system which concerns on 2nd Embodiment. It is a flowchart which shows the flow of a process of the broadcast system which concerns on 2nd Embodiment. It is a figure which shows the structural example of the ad hoc terminal which concerns on 3rd Embodiment. It is a flowchart which shows the flow of a process of the field strength priority mode (routing table system) which concerns on 3rd Embodiment. It is a flowchart which shows the flow of a process of Willingness priority mode (routing table system) which concerns on 3rd Embodiment. It is a flowchart which shows the flow of a process of the field strength priority mode (broadcast system) which concerns on 3rd Embodiment. It is a flowchart which shows the flow of a process of the broadcast system (Willingness priority mode) which concerns on 3rd Embodiment. It is a figure which shows the structural example of the ad hoc terminal which concerns on 4th Embodiment. It is a flowchart which shows the flow of the communication processing by the routing table system which concerns on 4th Embodiment. It is a flowchart which shows the flow of the communication processing by the broadcast system which concerns on 4th Embodiment. It is a figure which shows the structural example of the ad hoc terminal which concerns on 5th Embodiment. It is a figure which shows the example of the route formation setting table which concerns on 5th Embodiment. It is a figure which shows the example of a communication path | route. It is a figure which shows the flow of a process of the mode selection method in 5th Embodiment. It is a figure which shows the example of the communication path | route formed by 5th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1 'Ad hoc communication system 2, 2', 2a-2e Ad hoc terminal 3, 3A-3I Fixed terminal 4, 4A-4D Mobile terminal 6 Source terminal 7 Destination terminal 21 Communication part 22a-23e Processing part 23 Field strength Measurement unit 24a, 24b, 24e Storage unit 25 Sensor information acquisition unit 100 Control unit 221 Path selection unit 222 Willingness value setting unit 223 Mode selection unit 224 Hop number count unit 225 DBR / N calculation unit 226 Route formation method switching unit 241 Routing table 243 Willingness value setting table 244 Route formation setting table

Claims (9)

An ad hoc terminal that performs communication based on an ad hoc routing method,
As a relayable value obtained by quantifying the likelihood of becoming a relay terminal in the ad hoc terminal, a terminal that quantifies the radio wave intensity when the ad hoc terminal receives information and the state of the ad hoc terminal other than the ad hoc terminal The status value is set for each ad hoc terminal that makes up the network,
Receiving information including the terminal state value from a plurality of the other ad hoc terminals;
When there is information having a radio field intensity equal to or greater than a preset threshold, the other ad hoc terminal that has transmitted the information having the highest radio field intensity is selected as a communication target from among the plurality of received information.
When there is no information having a radio field strength equal to or greater than the threshold, among the received plurality of information, based on the terminal state value included in the received plurality of information, the other ad hoc terminals Radio wave intensity priority mode for selecting one as a communication target;
Determining whether or not there is the information having the terminal state value satisfying a predetermined criterion set in advance among the plurality of pieces of received information;
If the information having the terminal state value that meets the criteria exists, select a communication target terminal based on the terminal state value,
If the information having the terminal state value satisfying the criterion does not exist, one of the other ad hoc terminals that has transmitted the information having the highest radio field intensity among the plurality of received information Can be executed as a terminal state value priority mode for selecting as a communication target terminal,
An ad hoc terminal capable of switching to the radio field strength priority mode or the terminal state value priority mode based on a transmission speed in a communication path . An ad hoc terminal that performs communication based on an ad hoc routing method,
As a relayable value obtained by quantifying the likelihood of being connected to a relay terminal in the ad hoc terminal, a radio wave intensity when the ad hoc terminal receives information and a terminal state value obtained by quantifying the state of the ad hoc terminal itself , It is set for each ad hoc terminal you configure,
If the radio field intensity of the information received from the ad hoc terminal that is the transmission source is less than a preset threshold, the information is not transmitted,
When the radio field intensity of the received information is greater than or equal to a preset threshold, if the terminal state value of the ad hoc terminal itself is less than a preset threshold, the information is not transmitted,
If the terminal state value of the ad hoc terminal itself is equal to or greater than a preset threshold value, the radio field strength priority mode for transmitting the information to the other ad hoc terminals;
If the terminal state value of the ad hoc terminal itself is less than a preset threshold, information is not received from the other ad hoc terminals,
When the terminal state value of the ad hoc terminal itself is equal to or higher than a preset threshold value and the radio wave intensity of the received information is less than a preset threshold value, the information is not transmitted,
If the radio wave intensity of the received information is greater than or equal to a preset threshold, the terminal state value priority mode for transmitting the information to the other ad hoc terminals can be executed.
An ad hoc terminal capable of switching to the radio field strength priority mode or the terminal state value priority mode based on a transmission speed in a communication path . The ad hoc terminal according to claim 1 or 2 , wherein the terminal state value is set based on the number of sessions that is the number of communication paths formed by the ad hoc terminal itself. The ad hoc terminal is a mobile terminal mounted on a vehicle or a fixed terminal not mounted on a vehicle,
Wherein the terminal state value set to the mobile terminal is set to a value smaller than the terminal state value set to the fixed terminal,
The terminal state value is set to the fixed terminal, according to any one of claims 1 to 3, characterized in that it is set to a value larger than the terminal state value set to the mobile terminal Ad hoc terminal. The ad hoc terminal according to claim 4 , wherein the mobile terminal sets the terminal state value to a value corresponding to a moving speed of the mobile terminal itself. An ad hoc communication system having a communication network with ad hoc terminals performing communication based on an ad hoc routing method,
As a relayable value obtained by quantifying the likelihood of becoming a relay terminal in the ad hoc terminal, a terminal that quantifies the radio wave intensity when the ad hoc terminal receives information and the state of the ad hoc terminal other than the ad hoc terminal The status value is set corresponding to each ad hoc terminal constituting the communication network,
The ad hoc terminal is
Receiving information including the terminal state value from a plurality of the other ad hoc terminals;
When there is information having a radio field intensity equal to or greater than a preset threshold, the other ad hoc terminal that has transmitted the information having the highest radio field intensity is selected as a communication target from among the plurality of received information.
When there is no information having a radio field strength equal to or greater than the threshold, among the received plurality of information, based on the terminal state value included in the received plurality of information, the other ad hoc terminals Radio wave intensity priority mode for selecting one as a communication target;
Determining whether or not there is the information having the terminal state value satisfying a predetermined criterion set in advance among the plurality of pieces of received information;
If the information having the terminal state value that meets the criteria exists, select a communication target terminal based on the terminal state value,
If the information having the terminal state value satisfying the criterion does not exist, one of the other ad hoc terminals that has transmitted the information having the highest radio field intensity among the plurality of received information Can be executed as a terminal state value priority mode for selecting as a communication target terminal,
An ad hoc communication system , which can be switched to the radio field strength priority mode or the terminal state value priority mode based on a transmission speed in a communication path . An ad hoc communication system having a communication network with ad hoc terminals performing communication based on an ad hoc routing method,
As a relayable value obtained by quantifying the likelihood of becoming a relay terminal in the ad hoc terminal, a radio wave intensity when the ad hoc terminal receives information and a terminal state value obtained by quantifying the state of the ad hoc terminal itself are the communication It is set for each ad hoc terminal that makes up the network,
The ad hoc terminal is
If the radio field intensity of the information received from the ad hoc terminal that is the transmission source is less than a preset threshold, the information is not transmitted,
When the radio field intensity of the received information is greater than or equal to a preset threshold, if the terminal state value of the ad hoc terminal itself is less than a preset threshold, the information is not transmitted,
If the terminal state value of the ad hoc terminal itself is equal to or greater than a preset threshold value, the radio field strength priority mode for transmitting the information to the other ad hoc terminals;
If the terminal state value of the ad hoc terminal itself is less than a preset threshold, information is not received from the other ad hoc terminals,
When the terminal state value of the ad hoc terminal itself is equal to or higher than a preset threshold value and the radio wave intensity of the received information is less than a preset threshold value, the information is not transmitted,
If the radio wave intensity of the received information is greater than or equal to a preset threshold, the terminal state value priority mode for transmitting the information to the other ad hoc terminals can be executed.
An ad hoc communication system , which can be switched to the radio field strength priority mode or the terminal state value priority mode based on a transmission speed in a communication path . An ad hoc communication method in an ad hoc terminal that performs communication based on an ad hoc routing method,
As a relayable value obtained by quantifying the likelihood of becoming a relay terminal in the ad hoc terminal, a terminal that quantifies the radio wave intensity when the ad hoc terminal receives information and the state of the ad hoc terminal other than the ad hoc terminal The status value is set for each ad hoc terminal that makes up the network,
The ad hoc terminal is
Receiving information including the terminal state value from a plurality of the other ad hoc terminals;
When there is information having a radio field intensity equal to or greater than a preset threshold, the other ad hoc terminal that has transmitted the information having the highest radio field intensity is selected as a communication target from among the plurality of received information.
When there is no information having a radio field strength equal to or greater than the threshold, among the received plurality of information, based on the terminal state value included in the received plurality of information, the other ad hoc terminals Radio wave intensity priority mode for selecting one as a communication target;
Determining whether or not there is the information having the terminal state value satisfying a predetermined criterion set in advance among the plurality of pieces of received information;
If the information having the terminal state value that meets the criteria exists, select a communication target terminal based on the terminal state value,
If the information having the terminal state value satisfying the criterion does not exist, one of the other ad hoc terminals that has transmitted the information having the highest radio field intensity among the plurality of received information Can be executed as a terminal state value priority mode for selecting as a communication target terminal,
An ad hoc communication method characterized in that it can be switched to the radio field strength priority mode or the terminal state value priority mode based on a transmission speed in a communication path . An ad hoc communication method in an ad hoc terminal that performs communication based on an ad hoc routing method,
As a relayable value obtained by quantifying the likelihood of being connected to a relay terminal in the ad hoc terminal, a radio wave intensity when the ad hoc terminal receives information and a terminal state value obtained by quantifying the state of the ad hoc terminal itself , It is set for each ad hoc terminal you configure,
The ad hoc terminal is
If the radio field intensity of the information received from the ad hoc terminal that is the transmission source is less than a preset threshold, the information is not transmitted,
When the radio field intensity of the received information is greater than or equal to a preset threshold, if the terminal state value of the ad hoc terminal itself is less than a preset threshold, the information is not transmitted,
If the terminal state value of the ad hoc terminal itself is equal to or greater than a preset threshold value, the radio field strength priority mode for transmitting the information to the other ad hoc terminals;
If the terminal state value of the ad hoc terminal itself is less than a preset threshold, information is not received from the other ad hoc terminals,
If the terminal state value of the ad hoc terminal itself is equal to or greater than a preset threshold and the radio wave intensity of the received information is less than a preset threshold, the information is not transmitted,
If the radio wave intensity of the received information is greater than or equal to a preset threshold, the terminal state value priority mode for transmitting the information to the other ad hoc terminals can be executed.
An ad hoc communication method characterized in that it can be switched to the radio field strength priority mode or the terminal state value priority mode based on a transmission speed in a communication path .

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