JP2013074410A - Ad-hoc network communication terminal, ad-hoc network communication terminal control method, and ad-hoc network communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to control communication accuracy corresponding to temporal change in the transmission priority of data in an ad-hoc network.SOLUTION: An ad-hoc network communication terminal 100 comprises: a network interface 113 for exchanging a packet with another communication terminal 101; and an arithmetic unit 111 for performing processing of calculating the transmission priority of a packet by applying a lapsed time from packet reception clock time to next packet transmission clock time at the communication terminal to a temporal change function of the transmission priority depending on a packet type indicated by the packet for each packet received from the other communication terminal 101 via the network interface 113, processing of determining earlier transmission order according to height of the calculated transmission priority per packet among packets scheduled to be transmitted, and processing of transmitting each packet scheduled to be transmitted on the basis of the determined transmission order at an arrival of the next packet transmission clock time.

Description

  The present invention relates to an ad hoc network communication terminal, an ad hoc network communication terminal control method, and an ad hoc network communication system. Specifically, the present invention relates to communication accuracy corresponding to a time change related to data transmission priority in an ad hoc network. The present invention relates to a technology that enables control.

  An ad hoc network communication system (hereinafter referred to as an ad hoc network) is a communication system that enables communication terminals to autonomously connect to each other and communicate with each other. In this ad hoc network, unlike a conventional communication path determination method, a communication path setting operation by a user of a communication terminal and a dedicated communication device or communication infrastructure for managing communication such as a server or a router are not required. For this ad hoc network (also called multi-hop autonomous network), IETF (Internet Engineering Task Force) MANET (Mobile Ad-hoc Networks) working group and ROLLL (Routing Over Low power) Standardization is ongoing.

  As a method for determining a communication route in an ad hoc network, there are a method such as Reactive for determining a communication route at the start of communication, and Proactive for creating a routing table (route table) in advance by periodic information exchange. The communication terminals belonging to the ad hoc network are connected by the communication path determined by such a method. On the other hand, in such an ad hoc network, as a communication terminal constituting the network moves, the terminal joins or leaves the network, and the combination of communicable communication terminals changes. Further, even communication terminals subscribing to the network may not be able to communicate directly depending on the configuration of the communication path. In communication between such communication terminals, multi-hop communication using other terminals as repeaters is performed.

  In a multi-hop communication network, communication quality varies due to a complex combination of physical environment variations and communication circuit characteristics. For this reason, the communication time from the data transmission source to the final destination and the frequency of success / failure of communication vary, and it is difficult to maintain a certain accuracy in communication. As a method for improving the communication accuracy in such an environment, for example, a route with high communication quality is dynamically changed under the problems of stabilization of communication, avoidance of influence due to radio wave interference, and effective use of network resources. A technique for searching and communicating (see Patent Document 1) has been proposed. In this prior art, the route is dynamically changed with the communication quality and the number of hops to the final destination in a wireless multi-hop communication environment.

Japanese Patent No. 4222188

  When the above-described ad hoc network is used, it is easy to construct a network composed of a large number of communication terminals in units of several hundred units, such as a sensor network. On the other hand, when such a large number of communication terminals are in a network environment where the communication band is narrow and the communication speed is low, a transmission timing control method such as TDMA (Time Division Multiple Access) is applied, and the data transmission timing is communicated between the communication terminals. Will be adjusted.

  Here, the data transmitted by the communication terminal is important for its type of data, such as when the freshness is important and old data after a certain period of time is no longer needed, or when the importance increases with time. The transmission priority changes with time according to the event that triggered the data transmission. However, even if the data transmission timing between communication terminals is adjusted, no technique has been proposed that takes into account the temporal change in the transmission priority of data transmitted at each communication terminal.

  In an ad hoc network, the number of communication terminals easily increases and decreases due to changes in user convenience and communication environment. If the number of communication terminals belonging to a network varies greatly within a certain period of time, the amount of communication in the corresponding network also changes abruptly. Although fluctuations in the amount of communication on the network change the success rate of data transmission from the communication terminal, no technology has been proposed for controlling the data transmission priority in response to such a sudden change in the amount of communication.

  From the above, data that has a higher priority than other data is repeatedly retransmitted until transmission is successful, regardless of the value that changes over time, and packets of the relevant data may stay on the network. Arise. Alternatively, there is a case where a packet of the corresponding data is discarded when the transmission is not successful within a certain time or the upper limit number of retransmissions even though the data increases in priority, that is, value with time. In addition, despite the drastic increase in the amount of communication in the network, there is a possibility that data transmission priority is fixedly used, data retransmission in a narrow communication band is repeated, and transmission delay due to this is frequently caused.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a technique that enables control of communication accuracy corresponding to a time change related to data transmission priority in an ad hoc network.

  An ad hoc network communication terminal of the present invention that solves the above problems is a communication terminal having a communication function in an ad hoc network, and a network interface that exchanges packets with other communication terminals, and another communication that is received via the network interface. For each packet from the terminal, the transmission priority of the packet is applied by applying the elapsed time from the packet reception time to the next packet transmission time at the communication terminal to the time change function of the transmission priority according to the packet type indicated by the packet. A process for calculating the degree of transmission, a process for determining that the transmission order between the packets scheduled to be transmitted is earlier according to the calculated transmission priority for each packet, and the next packet transmission time Of each packet scheduled to be transmitted based on the determined transmission order. Characterized in that it and a computing device that performs processing to signals.

  The ad hoc network communication terminal control method according to the present invention includes a communication function provided in an ad hoc network and a communication terminal having a network interface for exchanging packets with other communication terminals. For each packet from the terminal, the transmission priority of the packet is applied by applying the elapsed time from the packet reception time to the next packet transmission time at the communication terminal to the time change function of the transmission priority according to the packet type indicated by the packet. A process for calculating the degree of transmission, a process for determining that the transmission order between the packets scheduled to be transmitted is earlier according to the calculated transmission priority for each packet, and the next packet transmission time Transmission of each packet scheduled to be transmitted based on the determined transmission order And executes a process of performing, the.

  The ad hoc network communication system of the present invention is an ad hoc network communication system including a plurality of communication terminals having a communication function in an ad hoc network, and the communication terminal includes a network interface for exchanging packets with other communication terminals, For each packet from another communication terminal received via the network interface, an elapsed time from the packet reception time to the next packet transmission time in the communication terminal in the time change function of the transmission priority according to the packet type indicated by the packet Is applied, and the transmission order between the packets scheduled to be transmitted is made earlier according to the process of calculating the transmission priority of the packet and the calculated transmission priority for each packet. When the next packet transmission time arrives , Based on the transmission order of the determined, in which and a computing device that executes processing for transmission of each packet to be transmitted, characterized in that.

  ADVANTAGE OF THE INVENTION According to this invention, control of the communication precision corresponding to the time change regarding the transmission priority of the data in an ad hoc network is attained.

It is a figure which shows the structural example of the ad hoc network system in this embodiment. It is a figure which shows the example of the connection terminal management table in this embodiment. It is a figure which shows the example of the communication path | route table | surface in this embodiment. It is a figure which shows the example of the ad hoc network communication path | route table in this embodiment. It is a figure which shows the example of the transmission timing management table in this embodiment. It is a figure which shows the example of the packet data table in this embodiment. It is a flowchart which shows the process procedure example 1 of the control method of the ad hoc network communication terminal of this embodiment. It is a flowchart which shows process sequence example 2 of the control method of the ad hoc network communication terminal of this embodiment. It is a flowchart which shows process sequence example 3 of the control method of the ad hoc network communication terminal of this embodiment. It is a flowchart which shows process sequence example 4 of the control method of the ad hoc network communication terminal of this embodiment. It is a figure which shows the example of a time change of the transmission priority in this embodiment.

--- System configuration ---
Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram illustrating a configuration example of an ad hoc network communication system 10 according to the present embodiment. An ad hoc network communication system 10 (hereinafter, system 10) shown in FIG. 1 is a computer system that enables control of communication accuracy corresponding to a time change regarding data transmission priority in an ad hoc network.

  In the system 10 of this embodiment illustrated in FIG. 1, an ad hoc network communication terminal 100 (hereinafter, communication terminal 100) forms an ad hoc network with another ad hoc network communication terminal 101 (hereinafter, other communication terminal 101). The communication network has many sets. As such a communication network, specifically, a sensor network, which is a wireless network premised on multi-hop communication, can be imagined. Further, the communication terminal 100 and the servers 140 and 141 are connected to the system 10 of the present embodiment via networks 130 and 131 which are external networks that are not ad hoc networks.

  The hardware configuration of the communication terminal 100 (the same applies to the other communication terminals 101) is as follows. The communication terminal 100 includes a storage device 114 configured with a suitable non-volatile storage device such as a hard disk drive, an internal memory 112 configured with a volatile storage device such as a RAM, a program 102 held in the storage device 114, and the like. The central processing unit 111 such as a CPU that performs various determinations, computations, and control processes and performs ad hoc network communication with the other communication terminals 101 and the networks 130 and 131. A communication device control unit 113 that communicates with the servers 140 and 141. The storage device 114 stores at least an ad hoc network communication path table 118 and a transmission timing management table 119 in addition to the program 102 for implementing functions necessary for the ad hoc network communication terminal 100 of the present embodiment. .

  The networks 130 and 131 to which the above-described communication device control unit 113 is connected are, for example, a mobile phone communication network, an optical line network, a public wireless LAN network, or the like. These networks 130 and 131 can be connected to the server 140 or the server 141, respectively.

  In addition, the above-described communication device control unit 113 includes the above-described networks 130 and 131 such as a communication interface (network interface) with other communication terminals 101 constituting an ad hoc network, and a mobile phone communication network, an optical line network, and a public wireless LAN network. Has a communication interface. The communication device control unit 113 selectively connects / disconnects to / from the plurality of networks 130 to 131 via this communication interface, transmits / receives packets to / from other communication terminals 101, determines whether communication is possible, measures traffic, and the like. Execute communication control. Note that the communication device control unit 113 uses, for example, a wireless LAN ad hoc mode, a device compatible with specific low power wireless communication, or a predetermined wireless communication protocol as a communication interface with other communication terminals 101 configuring the ad hoc network. A corresponding dedicated network device may be provided.

  Subsequently, functions provided in the communication terminal 100 of this embodiment (the same applies to the other communication terminals 101) will be described. As described above, the functions described below can be said to be functions implemented by executing the program 102 included in the communication terminal 100, for example. However, the functions provided in the communication terminal 100 may be realized not only by an example implemented by a program but also by a dedicated hardware device corresponding to the corresponding function.

  For each packet received from the other communication terminal 101 received via the communication device control unit 113, the communication terminal 100 changes the communication priority 100 from the packet reception time to the time change function of the transmission priority according to the packet type indicated by the packet. The function of calculating the transmission priority of the packet by applying the elapsed time until the next packet transmission time in FIG. The next packet transmission time is a data transmission timing scheduled for each communication terminal by a transmission timing control method such as TDMA (Time Division Multiple Access). Of course, the data transmission timing allocation method is not limited to TDMA, and other methods may be adopted. The time change function of the transmission priority will be described later.

  Further, the communication terminal 100 sets the transmission order among the packets scheduled to be transmitted earlier in the packet data table 120 of the storage device 114 according to the calculated transmission priority of each packet. Has the ability to make decisions.

  Further, the communication terminal 100 has a function of transmitting each packet scheduled to be transmitted based on the determined transmission order when the next packet transmission time arrives.

  Note that the storage device 114 of the communication terminal 100 may store a time change function of transmission priority for each packet type in advance. In this case, the communication terminal 100 performs a time change function corresponding to the packet type indicated by the packet for each packet received from the other communication terminal 101 received via the communication device control unit 113 in the process of calculating the packet transmission priority. Is selected in the storage device 114, and the elapsed time from the packet reception time to the next packet transmission time in the communication terminal 100 is applied to the corresponding time change function to calculate the transmission priority of the corresponding packet. This is preferable.

  Further, the communication terminal 100 determines that the number of retransmissions of each packet scheduled to be transmitted is larger in the packet data table 120 of the storage device 114 in accordance with the calculated transmission priority of each packet. If it has a function, it is preferable. In this case, when the next packet transmission time arrives, the communication terminal 100 executes transmission of each packet scheduled for transmission based on the determined transmission order, and limits the determined number of retransmissions when the transmission fails. It is preferable to execute a process for performing retransmission.

  Further, the communication terminal 100 receives a notification of occurrence of a predetermined event from the other communication terminal 101 on the ad hoc network or the servers 140 and 141 as predetermined devices via the communication device control unit 113, or the communication terminal 100 When the occurrence of a predetermined event is detected, it has a function to change the time change function by increasing or decreasing the amount of change of the transmission priority per time in the time change function of the transmission priority by a predetermined amount according to the type of the corresponding event. If so, it is preferable. Examples of events that the communication terminal 100 receives or detects include an event in which a certain communication terminal group stops (or stops) at a predetermined time, or joins (or joins) an ad hoc network from a predetermined time. . When such an event occurs, a large fluctuation occurs in the traffic in the ad hoc network. Therefore, in response to fluctuations in traffic accompanying events, the time change function is dynamically changed for the transmission priority of packets transmitted by the communication terminals 100 and the like, and the management of packets flowing in the ad hoc network is made efficient. This is preferable.

  In addition, when the communication terminal 100 receives data of a time change function to be used from the other communication terminal 101 on the ad hoc network or the servers 140 and 141 as predetermined devices via the communication device control unit 113, the communication device 100 For each packet received from the other communication terminal 101 received via the control unit 113, an elapsed time from the packet reception time to the next packet transmission time at the communication terminal 100 is applied to the time change function received as the one to be used. A function of calculating the transmission priority of the packet may be provided.

  In addition, the communication terminal 100, in the process of calculating the transmission priority, for each packet from the other communication terminal 101 received via the communication device control unit 113, each of the transmission priority and time change function included in the packet. The data is read, and the time change of the transmission priority is calculated by applying the elapsed time from the packet reception time to the next packet transmission time in the communication terminal 100 to the read time change function, and the calculated time change is A function of calculating the transmission priority of the corresponding packet by adding to the value of the transmission priority read from the packet may be provided.

  Further, the communication terminal 100 determines whether or not the calculated transmission priority of the packet indicates a predetermined value. If the transmission priority indicates the predetermined value, the communication terminal 100 determines that the transmission priority is invalid and discards the packet. May be provided.

  Note that the communication terminal 100 is, as an ad hoc network communication terminal, naturally provided with communication control for building an ad hoc network, specifically, functions for detecting other communication terminals 101, calculating routes, and building routes. Conventional techniques may be employed for basic functions for this ad hoc network. The communication terminal 100 also has a function of receiving a packet from another communication terminal 101 and storing the packet and various data indicated by the packet in a packet data table of the storage device 114. Of course, the communication terminal 100 is a terminal that performs ad hoc network communication, and creates a packet transmitted by itself, and also has a function of storing the created packet and various data related to the packet in a packet data table of the storage device 114. ing.

  1 is a general computer having a central processing unit 151, an internal memory 152, a communication device control unit 153, and a storage device 154, like the communication terminal 100. It has the composition of. The server 140 performs its function by the central processing unit 151 executing a program stored in the storage device 154 or the internal memory 152.

  The network 130 connected to the communication device control unit 153 of the server 140 is the Internet or an intranet, and may be physically a mobile phone communication network or a public wireless LAN network. The communication device control unit 153 performs communication control such as connection to the network 130, disconnection, packet transmission, packet reception, communication availability determination, and traffic volume measurement.

  The storage device 154 stores a communication control unit 155 as a program. The storage device 154 stores a communication path table 156, a connection terminal management table 158, and a data storage unit 157.

  The communication control unit 155 in the server 140 creates a communication path table 156, and executes general communication control such as control of an IP network via the network 130 using the communication path table 156. A conventional technique may be adopted as a method for creating the communication path table 156.

  Note that the programs in the communication terminals 100 and 101 and the servers 140 and 141 may be stored in advance in the respective storage devices, and other programs may be used via available storage media and communication media as necessary. It may be stored in the storage device from the device.

--- Data structure example ---
Next, an example of a data structure in a table used by the communication terminal 100 and the server 140 according to the present embodiment will be described. FIG. 2 is a diagram showing an example of the connection terminal management table 158 in the present embodiment. The connection terminal management table 158 illustrated in FIG. 2 is a table that stores information on the communication terminals 100 and 101, and is managed by the server 140. The connection terminal management table 158 includes data such as a terminal name 1201 which is an identifier of the communication terminal 100 managed by the server 140, a terminal status 1202 indicating the state of the communication terminal, and an effective time 1203 of information stored for the communication terminal. It is configured. The connection terminal management table 158 is generated by data input by the network administrator regarding the communication terminals constituting the ad hoc network, or the server itself establishes communication with the communication terminals 100 and the like in the ad hoc network. It can be assumed that the information is obtained by acquiring the information.

  FIG. 3 is a diagram showing an example of the communication path table 156 in the present embodiment. The communication path table 156 illustrated in FIG. 3 is a table that stores communication path information for all communication terminals 100 to which the server 140 can be connected. The communication path table 156 of this example conforms to a routing table using IP addresses. This communication path table 156 includes a destination address 1301 for storing the communication address of the communication terminal 100, a next hop address 1302, which is an address to be transmitted first to reach the destination address 1301, and a destination address 1301. It is composed of data such as an interface 1303 which is an interface name for communication. The communication path table 156 may be generated by the conventional technique.

  FIG. 4 is a diagram showing an example of the ad hoc network communication path table 118 in the present embodiment. The ad hoc network communication path table 118 illustrated in FIG. 4 is provided in the communication terminal 100 and is a table for managing and recording communication paths for establishing communication using the ad hoc network communication protocol. This ad hoc network communication path table 118 includes a terminal name 1401 that is an identifier of a communication terminal, a link state 1402 that indicates whether communication is possible, the number of hops 1403 that indicates how many times transfer is required when a packet is transmitted to the terminal name 1401, and the corresponding It is composed of data such as communication quality 1403 of an ad hoc network.

  FIG. 5 is a diagram showing an example of the transmission timing management table 119 in the present embodiment. The transmission timing management table 119 illustrated in FIG. 5 is provided in the communication terminal 100, and is a table for managing and recording at which time the communication terminal can transmit a packet. This transmission timing management table 119 includes a transmission start time 1501, which is a time at which packet transmission is started, a transmission time 1502 indicating how much data is transmitted from the transmission start time 1501, validity of information regarding such transmission time, and the like. It consists of data such as an effective time 1503 representing time. The data included in the transmission timing management table 119 becomes the data transmission timing scheduled for each communication terminal by the transmission timing control method such as TDMA (Time Division Multiple Access) as described above. The subject that performs such scheduling may be a dedicated management device that is communicably connected to the communication terminal 100 or the like, or may be the server 140 or 141. In any case, this transmission timing management table 119 is provided in advance in the communication terminal 100.

  FIG. 6 is a diagram showing an example of the packet data table 120 in the present embodiment. The packet data table 120 illustrated in FIG. 6 is provided in the communication terminal 100 and the like, and includes nine items of data 201 to 209 and a packet for each packet received from another communication terminal 101 or a packet that is to be transmitted by itself. The table stores the main body 210. Further, FIG. 6 shows a situation in which data regarding N packets from the first to the Nth is stored in the packet data table 120.

  In this packet data table 120, the final transmission destination 201 stores the final transmission destination address of a predetermined packet. The next transmission destination 202 stores an address to which the packet is to be transmitted next when viewed from the own communication terminal 101. In addition, the addresses of the final transmission destination 201 and the next transmission destination 202 may be acquired from the communication path table 156 provided in the server 140 by the communication terminal 100 or may be extracted from the received packet. The source 203 stores the address of the original communication terminal that has transmitted the packet. The address of the transmission source 203 is stored in the received packet.

  The current priority 204 stores a numerical value indicating the transmission priority of the packet at the time of packet reception. The current priority coefficient 205 is a coefficient indicating how the transmission priority of the packet at the time of packet reception changes with time. As for this coefficient, when the time change function is a linear function (eg, Y = aX + b, X is an elapsed time, and b is an initial value), the value of the slope a in the corresponding equation can be assumed. Therefore, the time change function in the present invention can be regarded as the stored value of the current priority coefficient 205. Each value of the current priority 204 and the current priority coefficient 205 may be stored in a received packet or may be newly set by the communication terminal 100 when a packet is received.

  The new priority 206 stores a numerical value calculated by the communication terminal 100 based on the current priority 204 and the current priority coefficient 206 before packet transmission. In addition, the new priority coefficient 207 stores a value that is dynamically changed by the communication terminal 100 based on the current priority coefficient 206, an occurrence event, and the like before packet transmission.

  In addition, the maximum number of retransmissions 208 stores the limit of the number of retransmissions, that is, the value of the maximum number of retransmissions, calculated by the communication terminal 100 based on the new priority 206 before packet transmission. The current transmission count 209 stores a value incremented by “1” by the communication terminal 100 for each transmission process (including retransmission) of the packet. The current number of transmissions 209 is data used when the communication terminal 100 compares the maximum number of transmissions 208 and determines whether or not to perform retransmission when packet retransmission is necessary.

--- Example of processing procedure 1 ---
Hereinafter, the actual procedure of the control method of the ad hoc network communication terminal in the present embodiment will be described with reference to the drawings. Various operations corresponding to the control method of the ad hoc network communication terminal described below are realized by programs that are read and executed by the communication terminals 100 constituting the system 10 in an internal memory or the like. And this program is comprised from the code | cord | chord for performing the various operation | movement demonstrated below.

  FIG. 7 is a flowchart showing a processing procedure example 1 of the control method of the ad hoc network communication terminal in the present embodiment. Here, first, main processing executed by the communication terminal 100 will be described. In this case, the communication terminal 100 determines whether or not it is necessary to create a new packet by itself (301). When it is necessary to create a packet by one's own mind, it is a case where the communication terminal 100 performs a packet transmission as a transmission source.

  Here, for example, the communication terminal 100 obtains a new measurement value (for example, a measurement value of a predetermined event measured by a sensor attached to the communication terminal 100), and detects that a specified event has occurred that is transmitted to the server 140. Thus, it is determined that packet generation is necessary (step 301: Yes), and new packet creation processing is executed (320).

  In this new packet creation process (320), the communication terminal 100 executes a packet creation process according to the protocol of ad hoc network communication, and then a process of storing the created packet and its information in the packet data table 120. The communication terminal 100 generates a record of the generated packet in the packet data table 120, and the communication path table 156 of the server 140, other communication terminals 101, etc. are displayed in the fields of the final transmission destination 201 and the next transmission destination 202 in the record. (For example, the IP address of the “final destination” server or the like, or the first hop from the communication terminal 100 during multi-hop transmission of packets from the communication terminal 100 to the “final destination”) The IP address of the other communication terminal 101 that is the destination = “next transmission destination”) is stored. The communication terminal 100 stores its own address in the transmission source 203 column in the packet data table 120. In the packet data table 120, the communication terminal 100 sets the values specified in the processing described later in each column of the current priority 204, the current priority coefficient 205, the new priority 206, and the new priority coefficient 207. Store.

  Further, the communication terminal 100 determines whether or not a packet reception process is necessary (302). This process is determined to be “necessary” when the communication terminal 100 receives a packet from another communication terminal 101, and is determined to be “unnecessary” when the packet is not received. When a packet is received from another communication terminal 101, the communication terminal 101 determines that a reception process is necessary (302: Yes), and executes a packet reception process (312) described later.

  Subsequently, the communication terminal 101 determines whether it is necessary to rearrange the records of each packet in the packet data table 120 in the numerical order of the transmission priority (303). When the packet transmission priority is set by the packet reception process (312) described above, the order of transmission priority varies in the packet data table 120 in relation to other packets. Judgment processing is executed. When the communication terminal 101 determines that rearrangement is necessary (303: Yes), the communication terminal 101 executes packet rearrangement processing (313). This packet rearrangement process (313) will be described later.

  Next, the communication terminal 100 determines whether it is necessary to transmit a packet (304). When the time at which the communication terminal 100 can execute packet transmission is reached (for example, time allocated in advance from the server 140 or the like based on TDMA), or other communication is performed by CSMA / CD (Carrier Sense Multiple Access with Collision Detection). When packet transmission is necessary (possible), for example, when it is determined that there is no carrier and transmission is possible, the communication terminal 100 executes packet transmission processing (314). The packet transmission process 314 will be described later. The above is the main processing flow executed by the communication terminal 100 of the present invention. Hereinafter, each process constituting the main process flow will be sequentially described.

--- Processing procedure example 2 ---
Next, the packet reception process (312) described above will be described. FIG. 8 is a flowchart showing a processing procedure example 2 of the control method of the ad hoc network communication terminal in the present embodiment. In this case, the communication terminal 100 determines whether the transmission priority and coefficient (time change function) stored in the packet received from the other communication terminal 101 are appropriate or inappropriate (401). Here, “inappropriate” means that the received packet does not store the transmission priority or the numerical value of the coefficient, or the stored numerical value exceeds the numerical value range defined in the ad hoc network communication system 10. And so on. Therefore, the communication terminal 100 confirms whether the transmission priority and the coefficient are stored for the received packet, or compares the transmission priority and the coefficient storage value with a predetermined reference value to determine the appropriate transmission priority and coefficient. Perform gender determination.

  When the communication terminal 100 determines that the transmission priority or the numerical value of the coefficient indicated by the received packet is inappropriate (401: No), the standard transmission priority and the coefficient stored in the storage device 114 in advance are applied. The packet transmission priority and coefficient are stored in the packet data table 120 (411). Note that the standard values of the transmission priority and the coefficient can be assumed to be uniform regardless of the packet type, or to be different for each packet type and application (application executed by the communication terminal).

  In step 401, the transmission priority and coefficient (time change function) stored in the packet received from the other communication terminal 101 are appropriate (401; Yes), or in step 411, the standard transmission priority and coefficient are set. After storing the transmission priority and coefficient of the corresponding packet in the packet data table 120, the communication terminal 100 newly calculates the transmission priority for the corresponding packet (402).

  In this new transmission priority calculation process, the communication terminal 100 sets the coefficient (time-varying function) included in the packet for the packet received from the other communication terminal 101 to the next time at the communication terminal 100 from the packet reception time. Multiply the elapsed time up to the packet transmission time to calculate a new transmission priority for the packet. For example, the coefficient is “1.5” (in this case, the time change amount of the transmission priority every 1 millisecond), and the elapsed time from the packet reception time to the next packet transmission time in the communication terminal 100 is “ If it is 1 millisecond, the value of the transmission priority can be calculated as “1.5 × 1 = 1.5”.

  In addition, when the storage device 114 stores a coefficient (time change function) for each packet type in advance (packet type coefficient table 121), the communication terminal 100 stores the packet type indicated by the received packet (eg, in the header of the packet). A coefficient (time change function) corresponding to the ID included in the storage device 114 is selected by the storage device 114, and the corresponding coefficient is multiplied by the elapsed time from the packet reception time to the next packet transmission time in the communication terminal 100, The new transmission priority of the packet may be calculated.

  Further, when data of a coefficient (time change function) to be used is received from the other communication terminal 101 on the ad hoc network or the servers 140 and 141 as predetermined devices, the communication terminal 100 is assumed to be used regarding the received packet. The transmission priority of the packet may be calculated by applying the elapsed time from the packet reception time to the next packet transmission time in the communication terminal 100 to the received coefficient.

  The communication terminal 100 reads each data of transmission priority and coefficient (time change function) included in the received packet, and uses the read coefficient as the elapsed time from the packet reception time to the next packet transmission time in the communication terminal 100. May be used to calculate the time change of the transmission priority, and add the calculated time change to the value of the transmission priority read from the packet to calculate the transmission priority of the packet. For example, the transmission priority read from the received packet is “2”, the coefficient is “1.5” (in this case, the time change amount of the transmission priority every 1 millisecond), and the communication is performed from the packet reception time. If the elapsed time until the next packet transmission time in the terminal 100 is “1 millisecond”, the time change of the transmission priority is calculated as “1.5 × 1 = 1.5”, and the transmission priority is added to this. By adding the degree “2”, the new transmission priority value can be calculated as “3.5” or the like.

  Here, the time change of the transmission priority will be described. FIG. 11 is a diagram illustrating a time change example of the transmission priority in the present embodiment. In this embodiment, it is assumed that the packet transmission priority in ad hoc network communication changes with time. The function indicating the graph in FIG. 11 is a time change function, and the slope of this graph is the “coefficient” described above. Both are graphs that can be expressed by a linear function.

  The time change function indicated by the graph 701 is a function in which the transmission priority decreases with time. The application of such a time change function is assumed to be a packet that is more valuable as the packet reaches the final destination in a shorter time from the time of transmission. For example, event data in the sensor network, data for notifying a change in state, and the like correspond thereto.

  On the other hand, the time change function indicated by the graph 702 is a function in which the transmission priority increases with time and the priority becomes “0” at a specific time. The application of such a time change function is assumed to be a packet to be transmitted to the final destination within a specific time. For example, sensor data in a sensor network, data periodically transmitted, and the like correspond to this.

  Further, the time change function indicated by the graph 703 is a function in which the transmission priority is fixed at a high value regardless of the passage of time. The application of such a time change function is assumed to be a limited priority packet. Alternatively, if the transmission priority is a function fixed at a low value regardless of the passage of time, a packet in the best effort is applied. In the time change function shown in the graph 703, the portion where the priority is 0 is omitted. However, in order to prevent the packet from being repeatedly transferred, the packet is discarded after a certain period of time. To do. Note that, in the example of the graph 703, the fixed transmission priority value indicates the emergency mode in which quick packet transmission is required, the normal mode in which packet transmission is normally performed at a required speed, and a predetermined packet. For example, a maintenance mode in which transmission is performed with a certain priority and the status of the route is determined may be set for each situation.

  Further, the time change function indicated by the graph 704 is a function in which the coefficient changes over time. Such a time change function is used when the communication efficiency of the entire network is improved by changing the coefficient according to the change of the network environment. In the sensor network, this time-varying function is used when the number of communication terminals on one network increases abruptly, or when other packet priorities are lowered to preferentially transmit specific packets. The dynamic change of the coefficient in the time change function will be described later.

  The communication terminal 100 stores the new transmission priority value calculated for the received packet in the corresponding record in the packet data table 120.

  Subsequently, the communication terminal 100 determines whether the new transmission priority calculated in the above processing is “0” (403). When the new transmission priority is “0” (403: Yes), the communication terminal 100 discards the corresponding packet and deletes the corresponding record in the packet data table 120 (431).

  Finally, the communication terminal 100 stores the received packet data (corresponding to the data item in the packet data table 120) obtained by the above processing in the packet data table 120 (404), and ends the processing. . In this storage, packet records are simply stored in the packet data table 120 in the order of reception.

--- Processing procedure example 3 ---
Next, the packet rearrangement process (313) described above will be described. FIG. 9 is a flowchart showing a processing procedure example 3 of the control method of the ad hoc network communication terminal in the present embodiment. The communication terminal 100 determines whether it is necessary to change the coefficient in the packet data table 120 (501). The case where there is a need for a change is when there is an instruction to change the coefficient from the server managing the network system, or when the arrival of a specific time set in advance as the coefficient change timing is detected (that is, the communication terminal itself) Can be assumed).

  Examples of the coefficient change instruction from the server or the like include those accompanying the occurrence notification of a predetermined event. An event in which a certain group of communication terminals stop (or have stopped) all at once at a predetermined time due to a power failure or the like, or join (or have joined) to an ad hoc network all at once from a predetermined time. When such an event occurs, a large fluctuation occurs in the traffic in the ad hoc network. Therefore, in response to fluctuations in traffic accompanying events, the time change function (coefficient which is the slope) of the transmission priority of packets transmitted by the communication terminals 100 and the like is dynamically changed so that the packets flowing in the ad hoc network It makes management more efficient.

  In addition, when the communication terminal 100 changes the coefficient, there are a case where the coefficient related to all packets is changed uniformly, or a case where only the coefficient related to a specific packet is changed based on the type of application handling the packet.

  When it is determined that the coefficient needs to be changed (501: Yes), the communication terminal 100 executes the coefficient change and the priority recalculation (511). When processing the coefficient change, the communication terminal 100 changes the time by changing the coefficient (that is, the amount of change of the transmission priority per time in the time change function) by a predetermined amount, for example, according to the type of the event or uniformly for all packets. The function will be changed. For example, it can be assumed that the initial coefficient is “1.5” and is reduced to “1.0” by the occurrence of an event. In the time change function of the graph 704 shown in FIG. 11, the slope of the graph changes from a certain time, which means that the coefficient is dynamically changed.

  The communication terminal 100 stores the changed coefficient value in the new priority coefficient 206 in the packet data table 120, calculates a new transmission priority value for the packet for which the coefficient has been changed, Store in the new priority 206. The transmission priority calculation process has already been described above.

  Subsequently, the communication terminal 100 determines whether or not the new transmission priority value calculated in step 511 is zero (502). This process searches the packet data table 120 for a record with a new priority 206 value of “0”, and if the record can be identified by this search, discards the record corresponding to the record and the record. (521).

  Next, the communication terminal 100 executes a packet rearrangement process based on the transmission priority (503). In this process, the communication terminal 100 rearranges the records related to each packet in the packet data table 120 in the descending order of the new priority 206 value. In the subsequent packet transmission processing, packet transmission is considered in this rearranged order.

  In addition, the communication terminal 100 executes the maximum transmission count setting process (504). In this processing, the communication terminal 100 determines the limit of the number of packet retransmissions, that is, the maximum number of transmissions based on the value of the new priority 206 described above. The maximum number of transmissions can be determined by uniformly determining the number of transmissions for each transmission priority value. For example, the maximum number of transmissions is set to “3” for packets whose transmission priority is “1” to “3”, and the maximum number of transmissions is “4” for packets whose transmission priority is “4” to “5”. This is the decision logic. In addition, the determination of the maximum number of transmissions is based on the time length of one packet transmission (length assigned by TDMA) and the total number of packets in the packet data table 120. In some cases, the value divided by is calculated as the maximum number of transmissions of each packet.

  Finally, the communication terminal 100 stores each value obtained by the above processing in the corresponding record in the packet data table 120 (505), and ends the processing.

--- Processing procedure example 4 ---
Next, the transmission process (314) described above will be described. FIG. 10 is a flowchart showing a processing procedure example 4 of the control method of the ad hoc network communication terminal in the present embodiment. In this case, the communication terminal 100 transmits each packet in the packet data table 120 in accordance with the arrival of the packet transmission timing assigned by TDMA.

  First, the communication terminal 100 executes processing for checking the remaining transmission time (601). This process is a process for confirming whether or not there is still a time during which packets can be transmitted in a time zone assigned in advance. If it is determined that there is no remaining time (601: No), the communication terminal 100 ends the transmission process execution.

  On the other hand, when there is remaining time (601; Yes), the communication terminal 100 executes a packet data acquisition process (602). In this process, the communication terminal 100 acquires a packet corresponding to the first record in the packet data table 120, that is, the record having the highest new priority 206 value.

  Subsequently, the communication terminal 100 executes transmission time confirmation processing (603). In this process, the communication terminal 100 determines the packet length of the packet acquired in the packet data acquisition process (602) described above and the communication speed of the communication terminal that is the packet destination (first hop destination) in the ad hoc network communication path table 118. From the (communication quality 1403 value), the transmission time of the corresponding packet is calculated, and it is determined whether one packet transmission is completed within the remaining transmission time (time confirmed in step 601). When it is determined that the communication cannot be completed (603: No), the communication terminal 100 ends the transmission process execution. On the other hand, if it is determined that packet transmission can be completed (603: Yes), the communication terminal 100 executes transmission processing (604). In this process, the communication terminal 100 transmits the corresponding packet acquired in step 602.

  Subsequently, the communication terminal 100 executes a process for determining whether transmission is successful (605). In this process, the communication terminal 100 confirms whether or not the packet transmitted at step 604 has been successfully transmitted. For the transmission confirmation process, a conventional method of determining whether there is an ack response from the packet transmission destination communication terminal may be employed. If the packet transmission is successful (605: Yes), the communication terminal 100 executes a data packet deletion process (651). In this process, the communication terminal 100 deletes the data of the corresponding packet from the packet data table 120. On the other hand, when the packet transmission is unsuccessful (605: No), the communication terminal 100 executes a transmission count increasing process (606). In this process, the communication terminal 100 increases the value of the current transmission count 209 by “1” in the record related to the packet in the packet data table 120.

  Subsequently, the communication terminal 100 executes a transmission count confirmation process (607). In this process, the communication terminal 100 checks whether the value of the current transmission count 209 is equal to or greater than the value of the maximum transmission count 208 in the record related to the packet in the packet data table 120. If the value of the current transmission count 209 is greater than or equal to the value of the maximum transmission count 208 (607: Yes), the communication terminal 100 deletes the corresponding packet and data related thereto from the packet data table 120 (608).

  Although the best mode for carrying out the present invention has been specifically described above, the present invention is not limited to this, and various modifications can be made without departing from the scope of the invention.

  According to the present embodiment, it is possible to control the communication accuracy corresponding to the time change regarding the transmission priority of data in the ad hoc network.

  At least the following will be clarified by the description of the present specification. That is, in the ad hoc network communication terminal, the storage device stores a time change function of transmission priority for each packet type in advance, and the arithmetic device calculates the network interface in the process of calculating the transmission priority. With respect to each packet received from another communication terminal via the network, the time change function corresponding to the packet type indicated by the packet is selected by the storage device, and the next packet transmission at the communication terminal from the packet reception time is selected as the time change function. The transmission priority of the packet may be calculated by applying the elapsed time up to the time.

  Further, in the ad hoc network communication terminal, the arithmetic unit performs a process of determining to increase the number of retransmissions of each packet scheduled for transmission according to the calculated transmission priority level of each packet, When the packet transmission time arrives, the transmission of each packet scheduled to be transmitted is performed based on the determined transmission order, and at the time of the transmission failure, the process of performing the retransmission up to the determined number of retransmissions is performed. There may be.

  In the ad hoc network communication terminal, the arithmetic device receives a notification of occurrence of a predetermined event from another communication terminal or a predetermined device on the ad hoc network via the network interface, or the communication terminal When the occurrence is detected, the processing for changing the time change function by increasing or decreasing the amount of change in the transmission priority per time in the time change function by a predetermined amount according to the type of the corresponding event may be executed. Good.

  In the ad hoc network communication terminal, when the arithmetic unit receives the data of the time change function from another communication terminal or a predetermined device on the ad hoc network via the network interface, the arithmetic unit receives the data via the network interface. For each packet from the other communication terminal, the transmission priority of the packet is calculated by applying the elapsed time from the packet reception time to the next packet transmission time at the communication terminal to the time change function that received the data. It may be a thing.

  Further, in the ad hoc network communication terminal, the arithmetic device, in the process of calculating the transmission priority, for each packet from the other communication terminal received via the network interface, the transmission priority included in the packet and the Read each data of the time change function, calculate the time change of the transmission priority by applying the elapsed time from the packet reception time to the next packet transmission time at the communication terminal to the read time change function, and calculate the time The change may be added to the read transmission priority value to calculate the transmission priority of the packet.

  In the ad hoc network communication terminal, the arithmetic unit determines whether the calculated transmission priority of the packet indicates a predetermined value. If the transmission priority indicates a predetermined value, the arithmetic priority is determined to be invalid. A process of discarding the packet may be executed.

  Further, in the ad hoc network communication terminal, the arithmetic device, for each packet from another communication terminal received via the network interface, compares the transmission priority indicated by the packet or the time change function with predetermined data, It may be determined whether or not the corresponding packet is inappropriate, and if the corresponding packet is inappropriate, a process of discarding the corresponding packet is executed.

10 ad hoc network communication system 100 ad hoc network communication terminal 101 (other) ad hoc network communication terminal 102 program 111 central processing unit (processing unit)
112 Internal memory 113 Communication device control unit (including network interface)
114 Storage device 118 Ad hoc network communication route table 119 Transmission timing management table 120 Packet data table 121 Packet type coefficient table 130, 131 Network 140, 141 Server 151 Central processing unit 152 Internal memory 153 Communication device control unit 154 Storage device 155 Communication control unit 156 Communication path table 157 Data storage unit 158 Connected terminal management table

Claims (10)

A communication terminal equipped with a communication function in an ad hoc network.
A network interface for exchanging packets with other communication terminals;
For each packet from another communication terminal received via the network interface, an elapsed time from the packet reception time to the next packet transmission time in the communication terminal in the time change function of the transmission priority according to the packet type indicated by the packet To calculate the transmission priority of the packet by applying
A process for determining that the transmission order between the packets scheduled to be transmitted is earlier according to the calculated transmission priority for each packet,
An arithmetic unit that executes processing for transmitting each packet scheduled to be transmitted based on the determined transmission order when the next packet transmission time arrives;
An ad hoc network communication terminal comprising: The storage device stores in advance a time change function of transmission priority for each packet type,
In the processing for calculating the transmission priority, the arithmetic device selects, with a storage device, the time change function corresponding to the packet type indicated by the packet for each packet received from the other communication terminal via the network interface. In addition, by applying an elapsed time from the packet reception time to the next packet transmission time in the communication terminal to the corresponding time change function, the transmission priority of the packet is calculated.
The ad hoc network communication terminal according to claim 1. The arithmetic unit is:
A process of determining to increase the number of retransmissions of each packet scheduled to be transmitted according to the calculated transmission priority of each packet,
When the next packet transmission time arrives, the transmission of each packet scheduled to be transmitted is performed based on the determined transmission order, and when the transmission fails, the process of performing the retransmission up to the determined number of retransmissions is performed. Is,
The ad hoc network communication terminal according to claim 1 or 2. The arithmetic unit is:
When the occurrence notification of the predetermined event is received from the other communication terminal or the predetermined device on the ad hoc network via the network interface, or when the communication terminal detects the occurrence of the predetermined event, depending on the type of the event, A process of changing the time change function by increasing or decreasing the amount of change in transmission priority per time in the time change function by a predetermined amount,
The ad hoc network communication terminal according to any one of claims 1 to 3. The arithmetic unit is:
When the data of the time change function is received from another communication terminal or a predetermined device on the ad hoc network via the network interface, the data is received for each packet from the other communication terminal received via the network interface. Applying the elapsed time from the packet reception time to the next packet transmission time in the communication terminal to the received time change function, to calculate the transmission priority of the packet,
The ad hoc network communication terminal according to any one of claims 1 to 3. The arithmetic unit is:
In the process of calculating the transmission priority, for each packet received from the other communication terminal received via the network interface, the transmission priority included in the packet and each data of the time change function are read, and the time change read Calculate the time change of the transmission priority by applying the elapsed time from the packet reception time to the next packet transmission time at the communication terminal to the function, and add the calculated time change to the read transmission priority value. And calculating the transmission priority of the packet,
The ad hoc network communication terminal according to any one of claims 1 to 5. The arithmetic unit is:
It is determined whether or not the calculated transmission priority of the packet indicates a predetermined value, and when the transmission priority indicates a predetermined value, it is determined that the transmission priority is invalid and a process of discarding the packet is executed.
The ad hoc network communication terminal according to any one of claims 1 to 6. The arithmetic unit is:
For each packet received from another communication terminal received via the network interface, it is determined whether or not the corresponding packet is inappropriate by comparing the transmission priority indicated by the packet or the time change function with predetermined data. If the packet is inappropriate, the process to discard the packet is executed.
The ad hoc network communication terminal according to any one of claims 1 to 7. A communication terminal having a communication function in an ad hoc network and a network interface for exchanging packets with other communication terminals,
For each packet from another communication terminal received via the network interface, an elapsed time from the packet reception time to the next packet transmission time in the communication terminal in the time change function of the transmission priority according to the packet type indicated by the packet To calculate the transmission priority of the packet by applying
A process for determining that the transmission order between the packets scheduled to be transmitted is earlier according to the calculated transmission priority for each packet,
A process for transmitting each packet scheduled to be transmitted based on the determined transmission order when the next packet transmission time arrives;
The control method of the ad hoc network communication terminal characterized by performing this. An ad hoc network communication system comprising a plurality of communication terminals having a communication function in an ad hoc network,
The communication terminal is
A network interface for exchanging packets with other communication terminals;
For each packet from another communication terminal received via the network interface, an elapsed time from the packet reception time to the next packet transmission time in the communication terminal in the time change function of the transmission priority according to the packet type indicated by the packet To calculate the transmission priority of the packet by applying
A process for determining that the transmission order between the packets scheduled to be transmitted is earlier according to the calculated transmission priority for each packet,
When the next packet transmission time arrives, based on the determined transmission order, comprising a processing unit that performs processing for transmitting each packet scheduled to be transmitted,
An ad hoc network communication system.

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