JP5175581B2 - Communication terminal, communication system, and program - Google Patents

Description

  The present invention relates to a communication terminal capable of forming an ad hoc network by realizing wireless communication with each of other communication terminals.

  In recent years, the use of an ad hoc network composed of a plurality of communication terminals has been expanded, and research on use in various scenes has been actively conducted. This is because an ad hoc network does not require an access point such as a base station, and therefore has an advantage that each communication terminal can independently construct a network.

In such an ad hoc network, the applicant of the present invention performs flooding to transmit emergency information from each communication terminal to each of the other communication terminals when an abnormal situation to be notified urgently occurs in any one of the communication terminals. It has been proposed to transmit (broadcast) information by a method (see Patent Document 1).
JP 2007-306547 A

However, the conventional flooding method has a problem that the success rate of communication between communication terminals varies greatly depending on the topology, and the success rate is not stable.
This is because, for example, when an area where communication terminals are densely formed is formed, it is not possible to cope with a dynamic topology change in an ad hoc network, such as an information collision easily occurring in this area.

  The present invention has been made to solve such problems, and its purpose is to provide a technique for stabilizing the success rate of communication between communication terminals, regardless of the topology as a network. Is to provide.

  In order to solve the above-described problem, a communication terminal capable of forming an ad hoc network by realizing wireless communication with each of other communication terminals is configured as follows in a first configuration (claim 1). It is possible to do.

  In this configuration, the position specifying means for specifying the own position as the position of the communication terminal, the own position storage means for storing the own position specified by the position specifying means in the storage unit, and the position specifying means The position notification means for notifying each other communication terminal of the received own position and the other position that is the position notified from each of the other communication terminals are stored in the storage unit in a state associated with the communication terminal of the notification source. The communication terminal and the others defined by the other position storage means to be executed, the latest own position stored in the storage unit, and the latest other position corresponding to each communication terminal stored in the storage unit A large value based on the number of other communication terminals located within a stable communication distance determined as a distance capable of stable wireless communication from the communication terminal based on the distance to each of the communication terminals Coefficient specifying means for specifying the transfer coefficient (hereinafter referred to as “self-transfer coefficient”), self-coefficient storage means for storing the self-transfer coefficient specified by the coefficient specifying means in the storage unit, and the coefficient specifying means The coefficient notification means for notifying each other communication terminal of the own transfer coefficient and the transfer coefficient notified from each of the other communication terminals (hereinafter referred to as “other transfer coefficient”) are associated with the communication terminal of the notification source. Other coefficient storage means to be stored in the storage unit in a state, and when receiving emergency information to be notified urgently from other communication terminals, the self-transfer coefficient and other transfer coefficient stored in the storage unit, respectively, If the order specified by the rank specifying means is higher than a certain level, the urgent information is passed to another pass. And a, and information transfer means for transferring to each terminal.

  In a communication terminal having such a configuration, when emergency information is received, the rank of its own transfer coefficient (own transfer coefficient) defined with respect to the transfer coefficient (other transfer coefficient) in another communication terminal is more than a certain level. The emergency information is forwarded only when it is above.

  This transfer coefficient has a higher value as the number of other communication terminals located within a distance (communication stable distance) in which stable wireless communication is possible, as viewed from the communication terminal itself, is higher. This means that the communication terminal itself can notify emergency information to a relatively large number of other communication terminals by transfer. In this case, if the emergency information is transferred by itself, the emergency information can be notified to many communication terminals so as to be known.

  On the other hand, the fact that the rank of the transfer coefficient is not higher means that there are few other communication terminals located within the communication stable distance in the communication terminal itself, and relatively few other communication terminals that can notify emergency information by the transfer. Means that. In this case, even if urgent information is transferred, it is not possible to notify many communication terminals and make it known. Therefore, it is desirable to leave the transfer to a communication terminal other than itself and not to transfer it.

In the above configuration, from the above viewpoint, the emergency information is transferred only when the rank of the self-transfer coefficient defined with other transfer coefficients is higher than a certain level.
As a result, emergency information is transferred only when it is suitable for disseminating emergency information in relation to other communication terminals. Therefore, if an ad hoc network is formed by this communication terminal, an unnecessarily large number of communication terminals are transferred. As a result, it is possible to suppress the collision of emergency information by suppressing traffic.

  As a result, even when a region where communication terminals are densely formed in an ad hoc network, it is possible to prevent information collision in this region, so the communication terminal can be used regardless of the topology as an ad hoc network. The success rate of communication between them can be made more stable than before.

  The coefficient specifying means in this configuration may specify the corresponding self-transfer coefficient calculated separately, or may calculate and specify the corresponding self-transfer coefficient each time.

  Further, the "latest own position" referred to when the coefficient specifying unit specifies the transfer coefficient is, for example, a case where a plurality of own positions are stored in the storage unit along a time series. If so, if it is the latest self-location identified based on the time series, and only the latest self-location is always stored in the storage unit, the self-location stored in that way It is.

  In the above configuration, when the emergency information is received, if the rank of the self-transfer coefficient defined with other transfer coefficients is higher than a certain level, the communication terminal (hereinafter “ The emergency information may be transferred regardless of the positional relationship with the “source terminal”.

  However, if the communication terminal itself is located outside the stable communication distance viewed from the transmission source terminal, the distance between the transmission source terminal and the communication terminal itself increases within the distance range from the transmission source terminal to the communication terminal itself as the distance increases. There is a high possibility that another communication terminal is located outside the stable communication distance.

  For such a communication terminal, since the position is outside the stable communication distance seen from both the transmission source terminal and the communication terminal itself, the emergency information transmitted from either the transmission source terminal or the communication terminal itself There is a high possibility that the data will not be received normally.

  Then, when the communication terminal itself is located outside the stable communication distance as viewed from the transmission source terminal, the communication terminal itself can receive the emergency information and the transfer coefficient ranks higher, so that the communication terminal itself transfers the emergency information. As a result, unless the data is transferred by another communication terminal, there is a high risk that a communication terminal that is not notified of emergency information remains as a result. This is contrary to the purpose of emergency information to notify all communication terminals.

  Therefore, even if the rank of the transfer coefficient is higher than a certain level, it is desirable not to transfer emergency information by lowering the rank as the distance from the communication stable distance viewed from the transmission source terminal becomes lower.

As a configuration for this purpose, for example, a second configuration (Claim 2) in which the above-described configuration is shown below can be considered.
In this configuration, when the emergency information is received from another communication terminal, the self-location stored in the storage unit and the communication terminal that is the sender of the emergency information (hereinafter referred to as “source terminal”) Based on the other position stored in the storage unit in association with the self-transfer coefficient stored in the storage unit, the distance from the own position to the other position in the source terminal When the emergency information is received from another communication terminal, the self-factor correction unit that corrects the coefficient so as to decrease as the distance from the stable communication distance increases, and is associated with the transmission source terminal that is the transmission source of the emergency information. A communication terminal other than the transmission source terminal based on the other position stored in the storage unit and the other position stored in the storage unit in association with the communication terminal other than the transmission source terminal. Vs. Each of the other transfer coefficients is reduced as the distance from the other position at the transmission source terminal to the other position at the communication terminal corresponding to the other transfer coefficient is further away from the stable communication distance at the transmission source terminal. And other coefficient correction means for correcting to.

  Then, the rank specifying means sets the own transfer coefficient corrected by the own coefficient correction means and the other transfer coefficient corrected by the other coefficient correction means, respectively, based on the values thereof. Specify the order of the coefficients.

  With this configuration, the transfer coefficient at each communication terminal is corrected to a smaller value as the distance from the communication stable distance at the transmission source terminal increases. The specified order can be lowered so that emergency information is not transferred.

  In addition, the case where the information transfer means in each of the above configurations transfers emergency information is “the case where the rank of the own transfer coefficient is higher than a certain level” means, for example, the number of other transfer coefficients stored in the storage unit Regardless, it may be always in the upper 1 to n (n is an arbitrary integer) position. Further, it may be higher than a specific ratio (for example, within 10%) of all other transfer coefficients stored in the storage unit.

  In addition, the information transfer means in each of the above configurations may transfer the emergency information immediately when the rank of the self-transfer coefficient is higher than a certain level, but the emergency information is transmitted through a standby time according to the rank. It may be transferred.

For this purpose, it is conceivable that each of the above-described configurations is as shown in a third configuration (claim 3).
In this configuration, when the rank of the self-transfer coefficient specified by the rank specifying unit is higher than a certain level, the waiting time until the emergency information is transferred becomes shorter as the rank is higher. Standby setting means for setting.

  When the rank specified by the rank specifying means is higher than a certain level, the information transfer means passes the emergency information to another communication terminal after waiting for the standby time set by the standby setting means. Forward for each.

With this configuration, the emergency information can be transferred in the order corresponding to the rank of the own transfer coefficient.
In this configuration, all the communication terminals that are “above a certain level” need only always transfer the emergency information, but only the communication terminals with higher ranks may transfer the emergency information.

For this purpose, it is conceivable that the third configuration is changed to a 3-1 configuration as described below.
In this configuration, when the emergency information is received from another communication terminal while waiting for the standby time set by the standby setting unit, the information transfer unit is configured to store the emergency information regardless of whether the standby time has elapsed. The transfer may be interrupted.

With this configuration, even if the communication terminal itself is “above a certain level”, it is possible to preferentially transfer emergency information when the communication terminal is a higher-ranking communication terminal.
In addition, the transfer coefficient specified in each configuration described above may be a value that increases as the number of other communication terminals located within the communication stable distance viewed from the communication terminal itself increases. It is also possible to consider the presence of other communication terminals.

For this purpose, a fourth configuration (claim 4) in which each of the above configurations is shown below can be considered.
In this configuration, the coefficient specifying means has a large value according to the number of other communication terminals located within the communication stable distance from the communication terminal, and is outside the communication stable distance and is used for wireless communication. Identifies the number of other communication terminals located within the maximum communication distance determined as the maximum possible distance and the self-transfer coefficient that becomes a large value according to the distance from the communication stable distance in the communication terminal To do.

  With this configuration, the self-transfer coefficient is determined in consideration of not only other communication terminals located within the communication stable distance viewed from the communication terminal itself but also other communication terminals located outside the communication stable distance. be able to.

Specifically, the self-transfer coefficient can be set to a large value according to the number of other communication terminals located within the maximum communication distance and the distance from the stable communication distance in the communication terminal.
In addition, the emergency information described above should normally be notified to all communication terminals that form the ad hoc network, but depending on the usage mode of the communication terminals that form the ad hoc network, notification that spreads in a specific direction as viewed from the transmission source terminal It is good also as what should be notified only with respect to all the communication terminals located in the area | region.

  For this purpose, all the emergency information is located in an area (hereinafter referred to as “notification area”) extending in a specific direction as viewed from the other communication terminal (hereinafter referred to as “transmission source terminal”) as the transmission source. On the premise that the information should be notified to the communication terminal, it is conceivable that each of the above configurations is configured as shown in a fifth configuration (claim 5).

  In this configuration, when the emergency information is received from another communication terminal, the latest local position stored in the storage unit and the transmission source terminal that is the transmission source of the emergency information are associated with the storage An area determination unit that determines whether or not the communication terminal is located in the notification area of the transmission source terminal based on the other position stored in the unit.

  Then, the coefficient specifying means is a self-transfer that becomes a large value according to the number of other communication terminals located in the notification area viewed from the communication terminal and within the stable communication distance from the communication terminal. When the coefficient is specified and the information transfer means determines that the communication terminal is located in the notification area in the transmission source terminal by the area determination means, the information transfer means transmits the emergency information to another communication terminal. Forward for each.

  In this configuration, since emergency information is not transferred unless the communication terminal itself is located within the notification area viewed from the transmission source terminal, in the ad hoc network formed by this communication terminal, the emergency information is transmitted from the transmission source terminal. The emergency information can be notified only to the communication terminal located in the notification area.

  In addition, as a usage mode of the communication terminal in this configuration, for example, when a communication terminal is mounted on a vehicle traveling on a road that is determined to pass only in a specific direction, and an emergency situation occurs in this vehicle It is possible to notify emergency information.

  In this case, even if an emergency situation occurs in a certain vehicle, it is assumed that the vehicle traveling in front of that vehicle (emergency occurrence vehicle) will move away from the emergency occurrence vehicle and be affected by the emergency situation. Therefore, it is not necessary to include it as a target for notification of emergency information.

  That is, in such a use mode, it is sufficient to notify the emergency information only to the communication terminal located in the area extending backward in the traveling direction when viewed from the communication terminal mounted on the emergency occurrence vehicle. An area that extends backward as viewed from the direction may be used as the notification area.

  Further, as a configuration for solving the above problem, there is a communication system (Claim 6) in which each of the communication terminals in any of the first to fifth configurations realizes an ad hoc network by realizing wireless communication. May be.

If it is this communication system, the effect | action and effect similar to those obtained by the communication terminal in each structure mentioned above can be acquired.
Further, as a configuration for solving the above-described problem, a program for causing a computer system to execute a processing procedure for causing all the means in any one of the first to fifth configurations to function as a program (Claim 7). Also good.

A computer system controlled by this program can constitute a part of any of the first to fifth configurations.
Note that the above-described program is composed of an ordered sequence of instructions suitable for processing by a computer system, and is provided to a communication terminal and a user using the same via various recording media and communication lines. Is.

Embodiments of the present invention will be described below with reference to the drawings.
(1) Overall Configuration As shown in FIG. 1, the communication terminal 1 includes a control unit 11 that controls the entire communication terminal 1, an operation unit 13 that receives user operations, a display unit 15 that displays various information, and other communication terminals. 1 includes a communication unit 17 that controls wireless communication with the GPS 1, a GPS reception unit 19 that acquires position information (coordinates) based on a GPS signal received from a GPS (Global Positioning System) artificial satellite, and other communication. A communication system can be configured with each terminal 1.

Each communication terminal 1 in this communication system is configured to be able to form an ad hoc network by realizing wireless communication with another communication terminal 1.
In this embodiment, the communication terminal 1 is mounted on each of a plurality of vehicles 100 traveling on a road that is determined to pass only in a specific direction (see FIG. 2), and each communication terminal 1 is connected via an in-vehicle network. The case where it is configured so that parameters (speed etc.) relating to the operation of the vehicle can be acquired will be illustrated.
(2) Processing by Control Unit 11 Hereinafter, various types of processing executed according to programs stored in a memory (storage unit) built in the control unit 11 will be described.
(2-1) Location Information Notification Process First, the procedure of the location information notification process that is started every time a predetermined notification cycle (Advertise Rate) arrives after the communication terminal 1 is started will be described with reference to FIG. .

  When the position information notification process is activated, first, position information is acquired via the GPS receiver 19 (s110), and the current position of the communication terminal 1 is specified based on the position information (s120).

Next, a predicted position where the communication terminal 1 is predicted to arrive at the next timing when the notification cycle arrives is specified (s130).
Here, a position information table stored in the built-in memory of the control unit 11 as a data table for registering the current position, predicted position, sequence number, and transfer coefficient (to be described later) of the communication terminal 1 (see FIG. 4A). From the current position registered here as a starting point, the direction of the current position specified in the above s120, toward the current position, corresponds to the notification cycle at the vehicle speed acquired through the in-vehicle network at this time In this case, the position that will be reached is calculated as the predicted position.

  Next, a transfer coefficient used for determining whether or not the communication terminal 1 transfers emergency information to be described later is based on an adjacent table in which information of each of the other communication terminals 1 located in the vicinity is registered. It is calculated (s140).

  This “adjacent table” is used to register the latest parameters such as identification information (node ID), current position, predicted position, context, sequence number, and transfer coefficient, which will be described later, of other communication terminals 1 located in the vicinity. The data table is stored in the built-in memory of the control unit 11 (see FIG. 4B). Of these, the “front-rear relationship” is a parameter (“front” or “rear”) indicating whether the vehicle is mounted in the forward or backward direction with respect to the traveling direction of the vehicle on which the communication terminal 1 is mounted. (See FIG. 2B).

  In this s140, first, from the current position of the communication terminal 1 itself identified in s120 (hereinafter also referred to as “own position”), another communication terminal 1 registered in the adjacent table (hereinafter referred to as “adjacent communication terminal 1”). ”) To the current position (hereinafter also referred to as“ other position ”), and based on this distance and the“ longitudinal relationship ”of the corresponding communication terminal 1, each of the adjacent communication terminals 1 relative to the communication terminal 1 itself is calculated. The positional relationship is specified. Then, the transfer coefficient P, which becomes larger as more adjacent communication terminals 1 are located under certain conditions around the communication terminal 1 itself, is expressed by the following formula 1 that defines each parameter as shown below. Calculated based on

Ds: Distance previously defined as a distance at which wireless communication by the communication terminal 1 itself can be stably performed (hereinafter referred to as “communication stable distance”)
Dm: Distance that is farther than the stable communication distance Ds and defined in advance as the maximum distance that can be wirelessly communicated (hereinafter referred to as “maximum communication distance”)
Do: Distance to the adjacent communication terminal 1 that is located within the range of the communication stable distance Ds to the communication maximum distance Dm and that is located behind the traveling direction of the communication terminal 1 itself N: Communication proximity distance Number of adjacent communication terminals 1 located within a distance range up to Dn (distance closer to a certain percentage (in this embodiment, 1/2) than communication stable distance Ds; Dn = Ds / 2) M: communication stable distance Ds The number of adjacent communication terminals 1 that are located within the distance range from the communication proximity distance Dn and that are located rearward with respect to the traveling direction of the communication terminal 1 itself. ), The adjacent communication terminal 1 located in the range from the communication proximity distance Dn to the communication proximity distance Dn and in the rear range from the communication stability distance Ds to the communication proximity distance Dn. The greater the number of Large value is calculated as the feed coefficient P (preceding equation 1). Further, the transfer coefficient P is equal to the number of adjacent communication terminals 1 located within the communication maximum distance Dm even outside the communication stable distance Ds, and from the communication stable distance Ds to the adjacent communication terminal 1. It becomes a large value according to the distance (after stage 1).

That is, a larger value is calculated as the transfer coefficient P as more adjacent communication terminals 1 are located in a specific region (see the shaded portion in FIG. 5) around the communication terminal 1 itself.
After the transfer coefficient is calculated in this way, the above-described position information table is updated (s150). Here, the “current position” in the position information table is updated to the current position (own position) specified in s120, the “predicted position” is updated to the predicted position calculated in s130, and the “sequence number” is updated. "Is incremented (+1), and" transfer coefficient "is updated to the transfer coefficient calculated in s140 (see FIG. 4B).

  Next, an Advertise packet that stores the current position, predicted position, sequence number, and transfer coefficient registered in the position information table at this time is generated (s160). In this Advertise packet, “TTL” (Time To Live) in the header information is set to “1”.

Then, after the Advertise packet generated in s160 is broadcast (s170), the position information notification process is terminated.
The Advertise packet broadcast in this way is received by each of the adjacent communication terminals 1 mounted on the vehicle existing within the communication range of the communication terminal 1, and each of the adjacent communication terminals 1 starts a positional relationship confirmation process described later. It will be.
(2-2) Positional Relationship Confirmation Processing Subsequently, the processing procedure of the positional relationship confirmation processing that is started every time an Advertise packet from another communication terminal 1 is received after the communication terminal 1 is started based on FIG. explain.

  When this positional relationship confirmation process is activated, it is first checked whether the Advertise packet received at the time of activation is the latest one transmitted from the same communication terminal 1 (s210). Here, the sequence number stored in the Advertise packet received upon activation is based on the sequence number registered in the adjacency table in association with the communication terminal (hereinafter referred to as the transmission source terminal) 1 that is the transmission source of the Advertise packet. Is larger, it is determined that the Advertise packet is the latest.

If it is determined in s210 that the Advertise packet is not the latest one (s210: NO), the positional relationship confirmation process is immediately terminated.
On the other hand, if it is determined in s210 that the Advertise packet is the latest one (s210: YES), the vehicle on which the transmission source terminal 1 is mounted is positioned either forward or backward with respect to the traveling direction. The “context” indicating whether or not is specified (s220).

  Here, as shown in FIG. 2B, an Advertise packet received upon activation is defined by defining a straight line B that is orthogonal to the straight line A passing through the current position and the predicted position registered in the position information table. If the current position of the adjacent communication terminal 1, that is, the current position (other position) of the adjacent communication terminal 1 is on the predicted position side of the communication terminal 1 itself with the straight line B as a boundary, “ “Previous” is identified as the context. On the other hand, if the current position of the transmission source terminal 1 is on the side opposite to the predicted position of the communication terminal 1 itself with the straight line B as a boundary, the “rear” indicating that it is located rearward in the traveling direction Identified as a relationship.

Then, after the adjacency table is updated (s230), the positional relationship confirmation process ends. Here, the current position, predicted position, sequence number, and transfer coefficient among the data records of the adjacent table corresponding to the transmission source terminal 1 (identification information thereof) are updated to those stored in the Advertise packet, and the context Is updated to the one specified in s220.
(2-3) Emergency Notification Processing Next, the emergency notification processing procedure that is repeatedly executed after the communication terminal 1 is activated will be described with reference to FIG.

  When the emergency notification process is started, first, an emergency situation (for example, sudden braking has been carried out, another vehicle has approached abnormally in this vehicle from the in-vehicle network in the vehicle in which the communication terminal 1 is mounted. Until the notification information for notifying is obtained (s310: NO).

  After that, when broadcast information is acquired (s310: YES), the communication mode by the communication unit 17 is an emergency mode in which an emergency notification is performed by a flooding method from a normal communication mode (normal mode) in which an Advertise packet is transmitted. (S320).

  Here, for example, the frequency band used for information transmission is changed to a frequency band different from the normal mode within the range that other communication terminals 1 can receive, or the protocol used for information transmission is changed to other communication terminals. The communication mode is switched to the emergency mode by changing to another protocol that 1 can handle.

Then, after emergency information (flooding packet) for performing emergency notification by flooding is generated for all the communication terminals 1 forming the network (s330), the emergency information generated in s330 is Broadcast (s340).
(2-4) Flooding Transfer Process Subsequently, the processing procedure of the flooding transfer process that is started every time the emergency information described above is received after the communication terminal 1 is started will be described with reference to FIG.

  When this flooding transfer process is activated, first, the emergency information that triggered the activation is displayed for a predetermined time (the time required for the emergency information broadcast by one communication terminal 1 to be transferred by another communication terminal 1). It is checked whether it is after reception within a predetermined time (that is, immediately after reception) (s410).

  If it is determined in s410 that it is immediately after reception (s410: YES), this flooding transfer process is immediately terminated, whereas if it is determined that it is not immediately after reception (s410: NO), the communication terminal 1 itself Is located in a region (hereinafter referred to as a “notification region”) that extends in a specific direction in which emergency information is to be notified with reference to a communication terminal (hereinafter referred to as a “transmission source terminal”) 1 that is a sender of emergency information. It is checked whether or not (s420).

This notification area is determined according to the usage mode of the communication terminal 1.
In the present embodiment, for example, the communication terminal 1 is mounted on a vehicle traveling on a road that is determined to pass only in a specific direction, and emergency information is notified when an emergency occurs in the vehicle. Thus, each communication terminal 1 is used. In this mode of use, even if an emergency situation occurs in a certain vehicle, the vehicle traveling in front of the vehicle (emergency occurrence vehicle) moves away from the emergency occurrence vehicle and is not affected by the emergency situation. Since it is difficult to assume, it is not necessary to include it in the target for notification of emergency information. That is, in such a case, it is sufficient to notify the emergency information only to the communication terminal located in the area extending backward in the traveling direction when viewed from the communication terminal 1 mounted on the emergency occurrence vehicle.

  Therefore, in this s420, it is determined whether or not the communication terminal 1 itself is located in the notification area of the transmission source terminal 1 by setting the area that extends backward as viewed from the traveling direction of the vehicle on which the transmission source terminal 1 is mounted. Is done. Specifically, the fact that the communication terminal 1 itself is located in the notification area of the transmission source terminal 1 is located behind the transmission source terminal 1, that is, the transmission source terminal 1 is the communication terminal 1 itself. Since it is located in the front, the communication terminal 1 itself is located in the notification area of the transmission source terminal 1 when the context of the transmission source terminal 1 registered in the adjacent table is “front”. It is determined that

When it is determined in s420 that the communication terminal 1 is not located in the notification area (s420: NO), the flooding transfer process is immediately terminated.
On the other hand, if it is determined in s420 that the communication terminal 1 itself is located in the notification area (s420: YES), the transfer coefficient of the communication terminal 1 itself, that is, the transfer coefficient registered in the position information table ( Thereafter, Pi (referred to as “self-transfer coefficient”) Pi (i = 0 in the self-transfer coefficient) is read (s430), and is corrected based on the positional relationship with the transmission source terminal 1 (s440).

  In this s440, first, the distance Dd from the own position registered in the position information table to the other position of the transmission source terminal 1 registered in the adjacent table is calculated. Based on the “relation”, the positional relationship between the communication terminal 1 and the transmission source terminal 1 is specified. Then, the self-transfer coefficient Pi is set so that the distance Dd, that is, the distance between the communication terminal 1 itself and the transmission source terminal 1 becomes larger as the distance from the communication stable distance Ds to the communication proximity distance Dn becomes closer. It correct | amends based on Formula 2-Formula 4.

In these equations, the self-transfer coefficient P0 is corrected so that the current position of the communication terminal 1 itself becomes smaller as the distance from the communication stable distance Ds at the transmission source terminal 1 is further away.

  Thus, after the own transfer coefficient Pi is corrected in s440, the transfer coefficient (hereinafter referred to as “other transfer coefficient”) Pi () in each of the other communication terminals 1 (excluding the transmission source terminal 1) registered in the adjacent table. In the other transfer coefficient, i = 1, 2,... N) is read (s450), and is corrected based on the positional relationship with the transmission source terminal 1 (s460), similarly to s440.

  In this s460, first, from any other position of the communication terminal (target communication terminal) 1 other than the transmission source terminal 1 registered in the adjacent table to the other position of the transmission source terminal 1 registered in the adjacent table. The distance Dd is calculated, and the positional relationship between the target communication terminal 1 and the transmission source terminal 1 is specified based on this distance and the “front-rear relationship” of the transmission source terminal 1. The other transfer coefficient Pi is set so that the distance Dd, that is, the distance between the target communication terminal 1 and the transmission source terminal 1, becomes larger as the distance range from the communication stable distance Ds to the communication proximity distance Dn becomes closer. The correction is made based on Equation 2 below.

  Next, based on the own transfer coefficient P0 corrected in s440 and the transfer coefficients P2 to Pn corrected in s460, the communication terminal 1 corresponding to each of these transfer coefficients Pi is assigned the transfer coefficient A priority pri corresponding to the size is assigned (s470). Here, “0” is assigned as the priority order to the communication terminal 1 corresponding to the largest transfer coefficient, and thereafter, the communication terminals 1 corresponding to the respective transfer coefficients are assigned in ascending order according to their sizes. An integer value is assigned.

  Next, it is checked whether or not the priority order pri assigned to the communication terminal 1 is higher than a certain level (s480). Here, “higher than a certain level” may be, for example, always in the upper 1 to n (n is an arbitrary integer) place regardless of the number of other transfer coefficients registered in the adjacent table. . Further, it may be higher than a specific ratio (for example, within 10%) of all other transfer coefficients registered in the adjacent table.

If it is determined in s480 that it is not higher than a certain level (s480: NO), the flooding transfer process is immediately terminated.
On the other hand, when it is determined in the above s480 that it is higher than a certain level (s480: YES), a waiting time Tw until the emergency information is transferred is set based on the priority order pri (s490). Here, a value (Ts · pri) obtained by multiplying the predetermined reference time Ts by the priority pri is set as the waiting time Tw.

Next, after setting the standby time Tw in s490, it is checked whether or not the standby time Tw has passed (s500).
If it is determined that the waiting time Tw has elapsed in s500 (s500: YES), the emergency information is transferred (s510), and then the flooding transfer process is terminated.

  On the other hand, if it is determined in s500 that the standby time Tw has not elapsed (s500: NO), it is checked whether or not the emergency information is re-received during this standby time Tw (s520), and re-reception is performed. If not (s520: NO), the process returns to s500.

On the other hand, if the emergency information is received again during the waiting time Tw (s520: YES), the process returns to 420.
(3) Flow of emergency notification Hereinafter, a process of notifying emergency information in the communication system as described above will be described.

  First, as shown in FIG. 2, assuming that an emergency occurs in a vehicle traveling on a three-lane road (see FIG. 100a), a communication terminal mounted on the vehicle in which an emergency has occurred in this way. 1 becomes the transmission source terminal 1 and transmits emergency information (s340 in FIG. 6).

  This emergency information is received by each of the other communication terminals 1 adjacent to the transmission source terminal 1, and each of the other communication terminals 1 that have received this emergency information is viewed from the traveling direction of the vehicle on which the transmission source terminal 1 is mounted. When it is located in a region (notification region) extending backward (s420 “YES” in FIG. 7), each of its own transfer coefficients P0 and other transfer coefficients P1 to Pn is corrected and the corresponding communication terminal A priority is assigned to each one (s470 in the figure).

  If the priority order pri assigned to its own transfer coefficient P0 is higher (s480: YES in the figure), after waiting for a waiting time Tw corresponding to the priority order (s490, s500 in the figure), the emergency information is sent. Transfer (s510).

  Here, except for the communication terminal 1 with the own transfer coefficient P0 having the highest priority pri, even if the priority pri of the own transfer coefficient P0 is higher than a predetermined value, When the transferred emergency information is received, the transfer is interrupted, and the determination is made again as to whether or not the transmission source terminal 1 is located in the notification area (s520 “YES” in the figure).

In this way, each of the other communication terminals 1 located in the notification area of each transmission source terminal 1, that is, located in the rearward direction of the transmission, starts from the transmission source terminal 1 that first transmitted the emergency information. Will go.
(4) Operation and Effect In the communication terminal 1 configured as described above, when the emergency information is received, the own transfer coefficient defined between the transfer coefficient (other transfer coefficient) in the other communication terminal 1 (Self-transfer coefficient) Only when the order of Pi is higher than a certain level ("YES" in s480 in the figure), the emergency information is transferred (s510 in the figure).

  This transfer coefficient Pi becomes a larger value as the number of other communication terminals 1 located within a distance (communication stable distance Ds) where stable wireless communication is possible when viewed from the communication terminal 1 itself (see Formula 1). That the order is higher means that the communication terminal 1 itself can notify emergency information to a relatively large number of other communication terminals 1 by transfer. In this case, if the emergency information is transferred by itself, the emergency information can be notified to many communication terminals 1 so as to be known.

  On the other hand, the fact that the order of the transfer coefficient Pi is not higher means that there are few other communication terminals located within the communication stable distance Ds viewed from the communication terminal 1 itself, and other communication terminals 1 that can notify emergency information by the transfer. Means relatively little. In this case, even if urgent information is transferred, it is not possible to notify many communication terminals 1 and make it known, so it is desirable to leave the transfer to other communication terminals 1 and not to transfer them. .

  From this point of view, in the above embodiment, the emergency information is transferred only when the rank of the own transfer coefficient P0 defined between the other transfer coefficients P1 to n is higher than a certain level. . As a result, the emergency information is transferred only when it is suitable for disseminating the emergency information in relation to other communication terminals 1, and therefore, an unnecessarily large number of communication terminals 1 in the ad hoc network including the communication terminal 1 are transferred. As a result, it is possible to suppress the collision of emergency information by suppressing traffic.

  As a result, even when an area where communication terminals 1 are densely formed in the ad hoc network, it is possible to prevent the occurrence of information collision in this area, so that communication can be performed regardless of the topology of the ad hoc network. The success rate of communication between the terminals 1 can be made more stable than before.

  In the above embodiment, when emergency information is received from another communication terminal 1, the transfer coefficient is corrected in consideration of the positional relationship with the transmission source terminal 1 (s430 to s460 in FIG. 7). The emergency information is transferred according to the order of the transfer coefficients corrected in this way (s510 in the figure).

  In this regard, for example, if the communication terminal 1 itself is located outside the communication stable distance Ds viewed from the transmission source terminal 1, the transmission is performed in the distance range from the transmission source terminal 1 to the communication terminal 1 itself as the distance increases. There is a high possibility that another communication terminal 1 is located outside the stable communication distance Ds viewed from both the original terminal 1 and the communication terminal 1 itself.

  For such a communication terminal 1, since the position is outside the stable communication distance Ds seen from both the transmission source terminal 1 and the communication terminal 1 itself, the transmission is performed from either the transmission source terminal 1 or the communication terminal 1 itself. Even if it is emergency information, there is a high possibility that it will not be received normally.

  Then, when the communication terminal 1 itself is located outside the communication stable distance Ds viewed from the transmission source terminal, the communication terminal 1 itself can receive emergency information and the transfer coefficient ranks higher, so that the communication terminal 1 itself is urgent. If the information is transferred, the risk that the communication terminal 1 to which the emergency information is not notified remains as long as the information is not transferred by another communication terminal 1. This is contrary to the purpose of emergency information to notify all communication terminals 1.

  Therefore, even if the transfer coefficient rank is higher than a certain level, it is desirable not to transfer emergency information so that the rank becomes lower as the distance from the communication stable distance Ds viewed from the transmission source terminal becomes lower.

  In order to realize this, in the above-described embodiment, the transfer coefficient is corrected in consideration of the positional relationship with the transmission source terminal 1 (s430 to s460 in the figure), and in accordance with the rank of the transfer coefficient thus corrected. Emergency information is transferred (s510 in the figure).

  Thereby, since the transfer coefficient in each of the communication terminals 1 forming the ad hoc network is corrected to a smaller value as the distance from the communication stable distance Ds in the transmission source terminal 1 is further increased, the communication terminals that are located at such distances. As much as 1, the order specified based on the transfer coefficient can be lowered so that emergency information is not transferred.

  In the above embodiment, when the rank of the self-transfer coefficient is higher than a certain level (s480 “YES” in FIG. 7), the emergency information is transferred after waiting for the waiting time Tw set in accordance with the rank. (S490 to s510 in the figure).

  If the emergency information is re-received during this waiting time Tw, the transfer of the emergency information is interrupted (s520 “YES” in the figure). As a result, even if the communication terminal 1 is “above a certain level” in the ad hoc network, the communication terminal 1 having a higher rank (highest rank in the present embodiment) may preferentially transfer the emergency information. it can.

  In the above embodiment, the self-transfer coefficient P0 is not only larger as the number of other communication terminals 1 located within the communication stable distance Ds viewed from the communication terminal 1 itself is larger, but is also outside the communication stable distance Ds. It can be specified as a value that also considers the presence of other communication terminals 1 located. Specifically, the number of other communication terminals 1 that are located within the distance range from the communication stable distance Ds to the communication proximity distance Dn and that are located rearward with respect to the traveling direction of the communication terminal 1 itself. The self-transfer coefficient P0 can be set to a large value according to M and the distance Do from the communication stable distance Ds in the communication terminal 1 (see Equation 1).

In the above embodiment, since the emergency information is not transferred unless the communication terminal 1 itself is located within the notification area viewed from the transmission source terminal 1 (s420 “YES” in FIG. 7), the communication terminal 1 In the ad hoc network formed by the above, the emergency information can be notified only to the communication terminal 1 in which the emergency information is located in the notification area viewed from the transmission source terminal 1.
(5) Modifications Embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and can take various forms as long as they belong to the technical scope of the present invention. Needless to say.

  For example, in the above embodiment, the case where the communication terminal of the present invention is mounted on each of the plurality of vehicles 100 is illustrated (see FIG. 2). However, the communication terminal of the present invention may be used in a mode implemented in a device other than a vehicle.

In the above embodiment, the own transfer coefficient is calculated in the position information notification process (s140 in FIG. 3), and the corresponding one of the separately calculated own transfer coefficients is required in the flooding transfer process. Accordingly, it is read and specified (s430 in FIG. 7).
However, each time the self-transfer coefficient is required in the flooding transfer process, the corresponding self-transfer coefficient may be specified by calculating in the same manner as in the position information notification process.

  In the above embodiment, when emergency information is received from another communication terminal 1, the transfer coefficient is corrected in consideration of the positional relationship with the transmission source terminal 1 (s430 to s460 in FIG. 7). The emergency information is transferred according to the order of the transfer coefficient corrected in this way (s510 in the figure). However, the emergency information may be transferred according to the rank of the transfer coefficient without considering the positional relationship with the transmission source terminal 1, that is, without correcting the transfer coefficient.

In the above embodiment, when the emergency information is retransmitted during the standby time Tw when the emergency information is transferred after the standby time Tw, the transfer of the emergency information is interrupted ("YES" in FIG. S520). . However, regardless of whether or not the emergency information is re-received during the standby time Tw, all the communication terminals 1 that are “above a certain level” may be configured to transfer the emergency information. Specifically, the standby is continued without checking whether or not the emergency information is received again during the standby time Tw (s500 “NO” → s500 in the figure is repeated). )do it.
(6) Correspondence with the Present Invention In the embodiment described above, s110 in FIG. 3 is position specifying means in the present invention, s150 in FIG. 3 is self-location storage means in the present invention, and s170 in FIG. 5 is the other position storage means in the present invention, s140 in FIG. 3 is the coefficient specifying means in the present invention, and s150 in FIG. 5 is the own coefficient storage means in the present invention. 5 is the coefficient notification means in the present invention, s230 in FIG. 5 is the other coefficient storage means in the present invention, s430 to s470 in FIG. 7 are the rank specifying means in the present invention, and s510 in FIG. S440 is the own coefficient correction means in the present invention, and s460 is the other coefficient correction means in the present invention. FIG. S490 shows standby setting means in the present invention, and FIG. S420 shows area determination means in the present invention.

Block diagram showing configuration of communication terminal Diagram showing usage of communication terminal Flowchart showing position information notification processing The figure which shows the data structure of various data tables Flow chart showing positional relationship confirmation processing Flow chart showing emergency notification processing Flowchart showing flooding transfer process

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Communication terminal, 11 ... Control part, 13 ... Operation part, 15 ... Display part, 16 ... Communication part, 17 ... Communication part, 19 ... GPS receiving part, 100 ... Vehicle.

Claims (7)

A communication terminal capable of forming an ad hoc network by realizing wireless communication with each of other communication terminals,
Position specifying means for specifying the own position which is the position of the communication terminal;
Own position storage means for storing the own position specified by the position specifying means in a storage unit;
Position notification means for notifying each of the other communication terminals of the own position specified by the position specifying means;
Other position storage means for storing the other position, which is the position notified from each of the other communication terminals, in the storage unit in a state associated with the communication terminal that is the notification source,
Distance between the communication terminal and each other communication terminal defined by the latest own position stored in the storage unit and the latest other position corresponding to each communication terminal stored in the storage unit Based on the transfer coefficient (hereinafter referred to as “own transfer coefficient”) which becomes a large value according to the number of other communication terminals located within the communication stable distance determined as the distance at which stable wireless communication can be performed from the communication terminal. A coefficient specifying means for specifying
Own coefficient storage means for storing the own transfer coefficient specified by the coefficient specifying means in a storage unit;
Coefficient notifying means for notifying each of the other communication terminals of the self-transfer coefficient specified by the coefficient specifying means;
Other coefficient storage means for storing the transfer coefficient notified from each of the other communication terminals (hereinafter referred to as “other transfer coefficient”) in the storage unit in a state in which the transfer coefficient is associated with the notification source communication terminal;
When urgent information to be notified urgently from another communication terminal is received, the self-transfer coefficient and the other transfer coefficient stored in the storage unit are ordered based on their values. A rank identifying means for identifying the rank;
An information transfer means for transferring emergency information to each of the other communication terminals when the rank specified by the rank specifying means is higher than a certain level. When the emergency information is received from another communication terminal, it is associated with the own location stored in the storage unit and the communication terminal (hereinafter referred to as “transmission source terminal”) that is the transmission source of the emergency information. Based on the other position stored in the storage unit, the self-transfer coefficient stored in the storage unit is calculated based on the stable communication distance in the transmission source terminal. A self-coefficient correcting means for correcting so as to decrease as the distance increases;
When the emergency information is received from another communication terminal, the other location stored in the storage unit in association with the transmission source terminal that is the transmission source of the emergency information, and communication other than the transmission source terminal Based on each of the other positions stored in the storage unit in association with a terminal, each of the other transfer coefficients corresponding to a communication terminal other than the transmission source terminal is transferred from the other position in the transmission source terminal to the other. Other coefficient correction means for correcting so that the distance to the other position in the communication terminal corresponding to the coefficient decreases as the distance from the communication stable distance in the transmission source terminal decreases,
The rank specifying means determines the self-transfer coefficient when the self-transfer coefficient corrected by the self-coefficient correction means and the other transfer coefficient corrected by the other coefficient correction means are ordered based on their values. The communication terminal according to claim 1, wherein a rank is specified. When the rank of the self-transfer coefficient specified by the rank specifying means is higher than a certain level, the standby setting for setting the time that is shorter as the rank is higher as the standby time until the emergency information is transferred Means,
When the rank specified by the rank specifying means is higher than a certain level, the information transfer means passes the emergency information to each of the other communication terminals after waiting for the standby time set by the standby setting means. The communication terminal according to claim 1, wherein the communication terminal is transferred to the communication terminal. The coefficient specifying means has a large value according to the number of other communication terminals located within the stable communication distance from the communication terminal, and is the maximum value that can be wirelessly communicated outside the stable communication distance. Identifying the number of other communication terminals located within the maximum communication distance determined as a distance, and a self-transfer coefficient that is a large value according to the distance from the stable communication distance in the communication terminal. The communication terminal according to any one of claims 1 to 3. For all communication terminals in which the emergency information is located in an area (hereinafter referred to as “notification area”) that extends in a specific direction as viewed from the other communication terminal that is the transmission source (hereinafter referred to as “transmission source terminal”) If the information is to be notified,
When the emergency information is received from another communication terminal, it is stored in the storage unit in association with the latest location stored in the storage unit and the transmission source terminal that is the transmission source of the emergency information. An area determination means for determining whether the communication terminal is located in the notification area in the transmission source terminal based on the other position being
The coefficient specifying means calculates a self-transfer coefficient that becomes a large value according to the number of other communication terminals located in the notification area viewed from the communication terminal and within the stable communication distance from the communication terminal. Specific,
The information transfer means transfers the emergency information to each of the other communication terminals when the area determination means determines that the communication terminal is located in the notification area of the transmission source terminal. The communication terminal according to any one of claims 1 to 4, wherein: Each of the communication terminals as described in any one of Claim 1 to 5 is comprised so that an ad hoc network may be formed by implement | achieving radio | wireless communication. The communication system characterized by the above-mentioned.   A program for causing a computer system to execute processing procedures for causing all the means according to any one of claims 1 to 5 to function.