JP4359159B2 - Ad hoc network system and ad hoc network terminal - Google Patents

Description

  The present invention relates to an ad hoc network system, and in particular, a system in which a plurality of ad hoc network terminals communicate with each other, and increases the possibility that mobile terminals such as PDAs, PCs, and mobile phone terminals can communicate with each other. About the system.

  Packet data communication using mobile phone terminals and the like has become widespread, and the use of the Internet in wireless LAN hot areas installed in public areas and stores is also increasing. There is a growing demand for IP data communication between terminals anytime and anywhere, and a communication system that can be used at higher performance and at lower cost is demanded.

  There is an ad hoc network as a new technology for realizing the above requirements. The ad hoc network system connects ad hoc network terminals brought close together on the spot to enable mutual communication. At that time, unlike a conventional mobile phone or wireless LAN, infrastructure equipment such as a base station does not need to be installed in advance in order to communicate from a terminal. For ad hoc networks, specifications are being studied and standardized mainly by the IETF (Internet Engineering Task Force) MANET (Mobile Ad-hoc Networks) working group.

  In an ad hoc network system, as the ad hoc network terminal moves, etc., the combination of terminals that can communicate with each other changes when a terminal joins or leaves the network. In addition, there may be cases where terminals that have joined the network cannot directly communicate with each other, and such terminals perform multi-hop communication using other terminals as repeaters.

  Due to the above features, data cannot be shared or exchanged on an ad hoc network system simply by broadcasting data to the periphery. As a conventional technique for this purpose, the technique disclosed in Patent Document 1 that performs data communication when terminals can communicate with each other, and the technique disclosed in Patent Document 2 that supports multi-hop communication by relaying and transferring data one after another. There is.

JP 2003-169370 A

JP 2002-234411 A

  The technique described in Patent Document 1 of the above prior art establishes a link with a partner terminal and performs communication. Therefore, there is a problem that it is not suitable for use in distributing data to a large number of terminals.

  Moreover, the technique described in Patent Document 2 of the above prior art is such that a terminal mounted on a mobile body such as an automobile communicates data to a terminal satisfying a condition in multihop. However, when one terminal tries to transmit data, it is out of the communication range, and when another terminal trying to receive does not satisfy the conditions, communication cannot be performed and the opportunity for communication is lost. There was a problem that could be.

  The present invention has been made to solve the above-described problems, and its purpose is to provide opportunities for terminals to communicate with each other in an ad hoc network system regardless of the type of communication or multi-hop communication in which a partner terminal is specified. To increase the availability of ad hoc terminals.

  Another object is to perform communication using an appropriate ad hoc network by changing transmission conditions according to the characteristics of data to be communicated.

  The present invention provides an ad hoc network system composed of a large number of terminals that can communicate by ad hoc network terminals joining in the same network in some cases and incapable of communicating with each other in other cases. Applied. In addition, in an ad hoc network system where direct communication and multi-hop communication may be possible even when they can communicate with each other, data can be distributed to each other, and data can be collected by recording received data I will provide a.

  According to the present invention, each ad hoc network terminal that holds data periodically transmits the data according to the timing condition of the data, and the terminal that receives the data becomes a terminal that holds new data, and thereafter the first data transmission Similar to the terminal, it is configured to be a terminal that periodically transmits data.

  With this configuration, data can be distributed not only to a terminal that can communicate with the first data transmission terminal, but also to a terminal that has become a new data transmission terminal by data reception and a terminal that has become newly communicable thereafter. A terminal that has received data from a new data transmission terminal also becomes another new data transmission terminal, and by repeating this, the number of new data transmission terminals increases, and data can be distributed to more terminals.

  In addition, a plurality of data transmission terminals can form a network with different other terminals at different positions along with their movements, and can transmit data. In this case, each transmitting terminal plays a role of carrying data to each network, and data distribution to terminals distant in time and space is possible.

  The transmission timing condition for periodic transmission may be transmitted or held in combination with the data body. For example, data distribution can be performed at a period according to the contents of the data body.

  Even if data that satisfies the deletion condition is deleted from the buffer by using a buffer that temporarily holds the data as a means for holding the data, a deletion condition such as elapse of a certain time is set for the data to be held good. Alternatively, data in another buffer may be deleted in order to secure an area for holding new data. At this time, use a storage device with a larger capacity than the buffer, and copy this data to the storage device that can hold data for a long time, such as HDD or flash memory, before deleting the data from the buffer. You can also. According to this, it is possible to collect large-capacity and long-term data by an ad hoc network terminal. The deletion condition may be transmitted and held in combination with the data body. For example, it is possible to perform data distribution with an expiration date according to the contents of the data body.

  The ad hoc network terminal may have data display means such as a monitor, and according to this, the distributed and collected data can be displayed one after another. Furthermore, filtering may be performed when attribute information is defined for data and displayed. According to this, it is possible to display only necessary types of data or not to display unnecessary data. In addition to the display, similar filtering may be performed in each process of transmission, reception, or holding. The attribute information may be transmitted and held in combination with the data body. For example, the distribution side can specify the attribute according to the contents of the data body and perform data distribution.

  The ad hoc network terminal can hold data actively input by the user in addition to data received from other terminals. For this purpose, the ad hoc network terminal may be provided with an input means such as a keyboard for manually adding data.

  With respect to the data transmission timing condition, it is possible to include a definition for delaying the periodic transmission performed by the own terminal when the same data is received from another terminal, thereby avoiding duplicate transmission. This can be realized, for example, by performing relay transfer for multi-hop communication together with data reception, resetting the waiting time until the next cycle transmission, and returning to the time of one cycle.

  In addition, the data transmission timing condition may include a condition regarding information related to position information and orientation of the ad hoc network terminal. For this reason, the ad hoc network terminal may have information acquisition means regarding position information and direction such as GPS (Global Positioning System). The transmission timing is determined based on the position information and direction information obtained from GPS and the like, and the position information and direction information included in the data transmission timing condition. According to this, for example, even when the data distribution position is different from the initial distribution terminal of the data, it is possible to distribute the data after carrying it through the other terminal to the target position.

  According to the present invention, in an ad hoc network system, regardless of the form of communication or multi-hop communication in which a partner terminal is specified, it is possible to increase the opportunities for communication between terminals and further increase the availability of ad hoc terminals.

  Another object is to change the transmission conditions according to the characteristics of the data to be communicated and to perform communication using an appropriate ad hoc network.

  Hereinafter, an embodiment according to the present invention will be described with reference to FIGS.

First, processing of the ad hoc network terminal according to the present embodiment will be described with reference to FIGS. 1 and 3.
FIG. 1 is a processing sequence diagram of an ad hoc network system according to the present invention.
FIG. 2 is a state transition diagram of an ad hoc network terminal mounted on an automobile.
FIG. 3 is a diagram illustrating an aspect when the transmission timing is delayed.

  In the present embodiment, an ad hoc network system including on-vehicle ad hoc network terminals mounted on an automobile or the like will be described as an example.

  In this embodiment, there are three in-vehicle ad hoc network terminals as shown in FIG. 2, and at the same time, two of the two terminals shift from a state where they can communicate with each other to a state where they cannot communicate, A state in which one of the terminals will shift from a state in which it cannot communicate with another terminal to a state in which communication is possible will be described.

  FIG. 2 shows the movement of each terminal and the state of data transmission when it is realized by three in-vehicle ad hoc network terminals that run on the road and go too far.

  The ad hoc network terminal 101 holds data 104 and periodically transmits data. Then, as shown in FIG. 2A, it is assumed that the distance between the ad hoc network terminal 101 and the ad hoc network terminal 102 is short and communication is possible. At this time, the ad hoc network terminal 102 receives the data transmission 107 from the ad hoc network terminal 101, and then the ad hoc network terminal 102 holds the received data 105 and periodically transmits the data in the same manner as the ad hoc network terminal 101. Send.

  Next, each terminal moves and changes to a state as shown in FIG. Here, it is assumed that the ad hoc network terminal 101 and the ad hoc network terminal 102 are still communicable.

  Then, as shown in FIG. 1, the ad hoc network terminal 102 intends to transmit the data 105 received from the ad hoc network terminal 101 in the next period 109. When the data transmission 110 is received within this period 109, the data to be transmitted and the received data are the same, so the data transmission is delayed for a certain period. This delayed pattern will be described later with reference to FIG. The reason for delaying the transmission of the same data in this way is to avoid unnecessary transmission and avoid communication congestion when there are many ad hoc network terminals in a narrow area.

  After the transmission is delayed once, the ad hoc network terminal 102 periodically transmits.

  Finally, when the state shifts to the state of FIG. 2C, the ad hoc network terminal 102 has already become incapable of communicating with the ad hoc network terminal 101, and can communicate with the ad hoc network terminal 103 instead.

  Therefore, in this state, the data transmission 113 from the ad hoc network terminal 102 is received by the ad hoc network terminal 103 and held as data 106. And the ad hoc network terminal 103 sets the period 114, and starts data transmission periodically. Thereafter, similarly, the ad hoc network terminals 101, 102, and 103 can perform data distribution by periodically transmitting data in a state where they can communicate with other terminals, and conversely, receive data from other terminals. You can also collect data by going.

FIG. 3 shows an aspect of data transmission delay as performed in the ad hoc terminal 102.
In the figure, one period is represented as T.

  FIG. 3A shows a method in which when data is received within a certain period, the period is shifted by one period T from the time when the data is received. According to this, when data is received at 0.8T, counting from the previous data transmission, the next data transmission time is when 1.8T has passed since the previous data transmission.

  FIG. 3B shows a method of shifting data from one cycle by one cycle T when data is received within a certain cycle. According to this, the time of the next data transmission is always when 2T has elapsed from the previous data transmission, counting from the previous data transmission.

  FIG. 3C shows a method in which when data is received within a certain period, the data is shifted by a predetermined time starting from the time when the data is received. For example, if it is shifted by 1.5T, when data is received at 0.8T from the previous data transmission, the next data transmission time has passed 2.3T from the previous data transmission. It will be time.

Next, the configuration of the ad hoc network terminal will be described with reference to FIG.
FIG. 4 is a configuration diagram of an ad hoc network terminal.

  As illustrated in FIG. 4, the ad hoc network terminal according to the present embodiment includes a CPU 301, a memory 302, and a transmission / reception device 307. In the memory 302, there is a buffer 304, which temporarily holds data. In addition, a storage device 308 that can hold data for a long time is provided. The storage device 308 is a non-volatile memory such as a flash memory, a hard disk drive, an optical disk drive, or the like.

  The storage device 308 may have registration data 309 that is original transmission data of the terminal itself. Here, when this registration data 309 is transmitted, it is assumed that it is once copied to the registration data 304 in the buffer 304 and used. Conversely, the received data 305 in the buffer may be copied and stored in the received data 310 in the storage device 308 for long-term storage. Further, an input / output device 311 for displaying the reception data 305 and inputting the registration data 309 may be provided. Furthermore, it has a GPS, a sensor, and a meter device 312 for measuring various types of local terminal information including the position of the local terminal and the direction of travel, and stores values obtained from these in the memory 302 as local terminal information 306. It can also be used.

Next, the structure of data communicated in the ad hoc network system of the present invention will be described with reference to FIG.
FIG. 5 is a diagram showing the structure of data communicated in the ad hoc network system of the present invention.

  Data 401 communicated in the ad hoc network system of the present invention includes header information 402 and a data body 403.

  The header information 402 includes a reception time, an identifier, a transmission condition, a deletion condition, a storage flag, an attribute 1,. The header information 402 is management information that is referred to when the ad hoc network terminal performs processing such as periodic data transmission, data deletion or display.

  The reception time is the time when this data is received. The identifier is a code attached to this data so that it can be uniquely identified. The transmission condition is a condition for transmitting this data, and includes a period, a position, a direction, a delay condition, and the like. The period is a value representing the time when this data is periodically transmitted, and this value is increased when it is desired to transmit data far, and this value is decreased when the distance is short. In addition, when using an ad hoc network system for advertising or the like, it is conceivable to shorten this cycle for data that is effective in a short period of time such as a time sale, and to increase this cycle to advertise for a long time.

  The position and direction of the transmission condition are the position and direction of the own terminal to be transmitted, and this is compared with the own terminal information 306 obtained from the GPS, and data is transmitted when satisfied. For example, when an ad hoc network terminal is in a certain store, it transmits advertisement data. When the ad hoc network terminal is heading for a certain store from the direction of travel of the car, the data is transmitted. An example of not transmitting is conceivable. Furthermore, in a traffic information system, an example of transmitting valid data when on a certain road is also conceivable.

  The transmission condition may be input from the terminal. In this way, the user can arbitrarily specify a desirable cycle or position depending on the situation on the terminal side.

  The delay condition is a condition that the transmission timing is delayed when the same data as the data to be transmitted is received. For example, when 0, the delay is not delayed, and when 1, the type is as shown in FIG. The transmission timing is delayed. In the case of 2, the transmission timing is delayed according to the type shown in FIG. This delay condition may also be input from the terminal.

  The position information includes an initial transmission position and a reception position. The initial transmission position is the position where this data was first transmitted. The reception position is a position where this data is received.

The deletion condition is a condition for deleting this data from the buffer 303, such as time, time, and position. The time and time of the deletion condition determine the time and time for deleting data, respectively. When communicating far away, take a long time to delete. The position of the deletion condition is that the data is deleted when this terminal is in that position. For example, when the terminal is outside a certain store, the data is deleted, and when the terminal is far from the urban area, An example of deleting the data can be considered because the effectiveness of the advertisement is reduced. This deletion condition may also be input from the terminal.

  The storage flag is a flag indicating whether this data is stored in the storage device 308.

  The attribute information 1,..., Attribute n is an attribute of the data. For example, the data is advertisement data, traffic information data, or the like.

  As a result, when advertising data is used, filtering can be performed such as displaying on the terminal display or not displaying the data. In addition, it is possible to categorize the advertisement data more finely and display only advertisements for products that interest you.

Next, processing of the ad hoc network terminal will be described with reference to FIGS. 6 and 7.
FIG. 6 is a flowchart showing processing of the ad hoc network terminal.
FIG. 7 is a diagram illustrating in detail the timing of data transmission.

  The ad hoc network terminal according to the present embodiment transmits data periodically as described above, and further, a buffer period called “jitter” is provided between the periods. The reason for providing jitter is, for example, to prevent multi-hop relay transmission from being simultaneously performed by a plurality of terminals and causing messages to collide and be discarded. In addition, since all terminals can use the transmission condition value included in the header information 402 of the data 401 as the data transmission cycle, the next cycle transmission timing is set at both the transmission side and the reception side terminals. For example, there is a reason to prevent a collision from happening.

  This is illustrated in FIG. 7 (a). Here, one cycle is represented by T, and the jitter period is represented by ΔT.

  The ad hoc network terminal of this embodiment has a period timer for counting periods, a jitter timer for counting jitter, and a deletion timer for counting time for deleting data.

  First, when the ad hoc network terminal has the registration data 309 in the storage device 308, the ad hoc network terminal temporarily copies it as the registration data 304 in the buffer 303 (step 501). Subsequently, a jitter timer for waiting for transmission is set (step 502).

  In this embodiment, a jitter timer is set before data transmission, and actual transmission is performed when the jitter timer times out.

  Although different from the present embodiment, it is also possible to transmit the registration data 304 when a combination condition with other conditions such as position information is satisfied instead of immediate transmission. In this case, a periodic timer is set instead of the jitter timer. To do. Regardless of which timer is set, the subsequent processing is the same as in the case of received data, so the following mainly describes the processing of received data.

  When receiving data (step 503), the ad hoc network terminal checks whether the received data matches any data already buffered (step 504).

  If the received data does not match, the received data is held in the buffer (step 505), and a deletion timer is set according to the deletion condition (step 506).

  In this embodiment, the deletion condition is deleted when a certain period of time has passed. However, if the terminal is removed from a specific geographical area, for example, deletion under conditions relating to location information such as deletion is also possible. It is. In that case, for example, the local terminal 306 may be updated with the values acquired by accessing the GPS, sensor, and meter device 312 periodically, and this may be checked to determine whether the condition is satisfied. . The terminal displays data received using the input / output device 311. At this time, the result of filtering according to the filter condition included in the data or determined by the terminal itself may be displayed (step 507).

  Then, a jitter timer is set as preparation for transmitting the data (step 509).

  On the other hand, if the received data matches the already buffered data, the periodic timer or the jitter timer is set to perform periodic transmission for the data, so that it is canceled (step 508).

  Then, a new cycle timer is set (step 512).

  This means that when the same data to be transmitted is received, the cycle timer is newly counted, and therefore the data transmission timing is delayed.

  As shown in FIG. 7B, when data is received during the counting of the jitter timer, it is as shown in FIG. 7B. When data is received during the counting of the period timer, as shown in FIG. 7C. Become. In other words, the processing of this flowchart is a method of delaying the transmission timing of the type shown in FIG. 3A, and the transmission timing is delayed by one cycle T from when data is received.

  When the jitter timer times out (step 501), data transmission corresponding to the timer is performed (step 511). After the transmission, a periodic timer is set in order to enter the next periodic transmission waiting state (step 512).

  When the periodic timer times out (step 513), the local terminal state 306 is updated with the values acquired by accessing the GPS, sensor, and meter device 312 in order to take into account the conditions related to the position information (step 514). Subsequently, the terminal status is checked (step 515). If transmission is possible, a jitter timer is set and transmission preparation is started (step 516). Otherwise, transmission in the current cycle is postponed and the next cycle timer is set (step 512).

  If the deletion timer has timed out (step 517), it is checked whether the data has already been stored in the storage device 308 (step 518), and if not, after copying the data as the received data 310 in the storage device 308 ( In step 519), the received data 305 in the buffer is deleted, and the corresponding transmission timer is also released (step 520).

  Although different from the present embodiment, the stored check and data copy may be performed at an opportunity other than immediately before the buffer deletion, for example, by providing a check cycle. By storing data in the storage device 308 that has a large capacity compared to the buffer and can store data for a long period of time, for example, the data collected by running around the in-vehicle ad hoc network terminal can be checked later. Is possible.

  As described above, according to the present embodiment, even in a set of ad hoc network terminals that are not communicable with each other, each ad hoc network terminal continues to transmit data periodically to communicate at other times. Data distribution and collection can be performed when possible. In addition, by defining transmission conditions combined with location information and time information, for example, information delivery specifying a location and time can be carried in advance from another location to another terminal. It can be realized. Furthermore, by moving with an ad hoc network terminal, data unique to the spot can be collected and recorded in a long-term storage device, and later checked slowly.

It is a process sequence diagram of the ad hoc network system which concerns on this invention. It is a state transition diagram of the ad hoc network terminal mounted in a motor vehicle. It is a figure which shows the aspect when delaying a transmission timing. FIG. 4 is a configuration diagram of an ad hoc network terminal. It is a figure which shows the structure of the data communicated with the ad hoc network system of this invention. It is a flowchart which shows the process of an ad hoc network terminal. It is a figure shown in detail about the timing of data transmission.

Explanation of symbols

  101, 102, 103 ... ad hoc network terminal, 104, 105, 106 ... data, 301 ... CPU, 302 ... memory, 303 ... buffer, 307 ... transmission / reception device, 308 ... recording device, 311 ... input / output device, 312 ... GPS, Sensor, meter device.

Claims (9)

In an ad hoc network system composed of a plurality of ad hoc network terminals and configured to communicate with each other,
Transmission conditions are set for the data to be communicated.
The ad hoc network terminal has means for holding the data, means for transmitting and receiving the data, and means for acquiring either or both of the position information and direction information of the ad hoc network terminal itself ,
The transmission condition includes a period from reception from another terminal to transmission to the other terminal, and one or both of position information and direction information of the ad hoc network terminal itself ,
The ad hoc network terminal, when transmitting the data, according to the transmission conditions, and either or both of the information on the position information and orientation included in the transmission condition, of the ad hoc network terminal itself obtained from the means for obtaining An ad hoc network system characterized by periodically transmitting the data to other ad hoc network terminals based on a result of comparing and determining either or both of position information and direction information. The transmission conditions are:
2. The ad hoc network according to claim 1, further comprising a condition that the next transmission timing is delayed when the ad hoc network terminal receives the same data as the data to be transmitted within the period of transmission. system. In ad hoc network terminals that communicate with each other data for which transmission conditions are defined,
This ad hoc network terminal
Means for holding the data;
Means for transmitting and receiving the data;
Means for acquiring one or both of the location information and orientation information of the terminal,
The transmission condition includes a period from reception from another terminal to transmission to the other terminal, and one or both of position information and direction information of the own terminal,
The ad hoc network terminal, when transmitting the data, according to the transmission conditions, and either or both of the information on the position information and orientation included in the transmission condition, of the ad hoc network terminal itself obtained from the means for obtaining An ad hoc network terminal characterized by periodically transmitting the data to another ad hoc network terminal based on a result of comparing and determining either or both of position information and direction information.   The ad hoc network terminal according to claim 3, further comprising means for setting the transmission condition. A buffer for temporarily holding the data;
Deletion conditions are defined for the data held in the buffer,
4. The ad hoc network terminal according to claim 3, wherein the data held in the buffer is deleted when the data deletion condition is satisfied or an area for holding other data is secured. . A storage device for holding the data for a long time;
4. The ad hoc network terminal according to claim 3, wherein data not stored in the storage device is copied from the buffer to the storage device before the data is deleted from the buffer.   4. The ad hoc network terminal according to claim 3, further comprising means for displaying the held data. Attribute information is defined for the retained data,
4. The ad hoc network terminal according to claim 3, wherein filtering is performed based on the attribute information when the data is processed.   4. The ad hoc network terminal according to claim 3, further comprising means for inputting the data to be communicated.

Images