JP3738356B2 - Wireless communication network system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wireless communication network technology in which a plurality of devices transmit and receive data by wireless communication, and in particular, a wireless terminal of a transmission source connected to a wireless communication network transmits various pieces of information in packets, and transmits to other wireless terminals The present invention relates to a technique used in a system for transferring to a destination wireless terminal while repeating relaying, and further relates to a technique for investigating and managing a communication path with a wireless terminal existing in the vicinity and a technique for transferring information between wireless terminals. .
[0002]
[Prior art]
FIG. 50 shows an example of the configuration of a wireless communication network system. In the figure, A to J indicate wireless terminals installed in a distributed manner. Since the distance that can be directly communicated by itself is generally limited, each of the wireless terminals A to J cannot directly communicate with all of the wireless terminals constituting the system. However, all the wireless terminals A to J can directly communicate with one or more wireless terminals, and can communicate with all wireless terminals constituting the system via other wireless terminals. . A solid line in the figure indicates a communication path through which the wireless terminals A to J can directly communicate.
[0003]
Conventionally, when packet communication is performed in a wireless communication network system having such a topology, a communication path between wireless terminals is not changed, and a fixed one is always used. Therefore, since it is necessary to ensure good quality with a considerable margin for these communication paths, these fixed communication paths are determined by the method described below.
[0004]
First, the communication path between each wireless terminal was assumed from the physical location information of the wireless terminal. Next, for example, the communication quality of the communication channel assumed by measuring the electric field strength at the other end of the test radio wave transmitted from one end, or measuring the bit error rate and the packet reception rate by performing a data communication test, etc. The communication channel that is actually used is only the communication channel that is determined to be able to ensure good quality.
[0005]
The relay route of the data packet (hereinafter simply referred to as a packet) when performing packet transfer communication in this wireless communication network system is transmitted by adding the information related to the relay wireless terminal to the packet and sending this route information to each packet. Each relay wireless terminal manages a method of transferring a packet while referring to the relay wireless terminal, and information on the next relay wireless terminal corresponding to the final destination of the packet, and transfers the packet based on this information. There was a way to go. The latter needs to have individual relay terminal information for each wireless terminal, while the former only needs to recognize the system topology only at the packet source, such as when changing the system Compared to the latter, the former is more flexible. In any case, conventional packet transfer communication in this system is performed based on a preset fixed relay route.
[0006]
[Problems to be solved by the invention]
The wireless communication network system that uses the above-described fixed communication path and performs packet transfer by a fixed relay route has the following problems.
[0007]
(1) Since the wireless communication path is easily affected by the surrounding environment where it is installed, the quality of the communication path between the wireless terminals assumed by the physical location information of the wireless terminals is not always good.
[0008]
(2) Since it is necessary to secure good quality with a considerable margin for the fixed communication path, the communication path was designed in a considerably short distance.
(3) The surrounding environment where the system is installed often changes gradually after installation, and the communication path set at the time of installation may disappear later or the possibility of a new communication path may occur. .
[0009]
The present invention aims to provide a wireless communication network system that automatically selects a communication path and a relay route according to the communication quality at that time in order to solve these problems described above, and in particular, the communication path. An object of the present invention is to enable a system design that effectively utilizes the communicable distance of a wireless terminal by minimizing a margin of communication quality for selection.
[0010]
[Means for Solving the Problems]
  In order to achieve the above object, the present invention adopts the following configuration.
  First, the invention according to claim 1 is configured by a plurality of wireless terminals that perform wireless data communication, and any of the wireless terminals can be directly or via one or more other wireless terminals with all other wireless terminals. In a wireless communication network system capable of communication, the wireless terminal,Communication quality diagnosis means for determining whether or not the communication path can be adopted as a communication path for direct communication by diagnosing the communication quality of the communication path for direct communication with other wireless terminalsAnd presence notification means for notifying other wireless terminals of their own presence, and the communication quality diagnosis means performs notification by the presence notification means of the wireless terminal that can be directly communicated for a predetermined time. Determining a communication path with the wireless terminal that is considered to be capable of direct communication when the above or a predetermined frequency is not confirmed,With featuresTo do.This configuration allows you to select only reliable channels.TheAdopted as a direct communication pathIn addition, the reliability diagnosis of the communication path that causes an increase in traffic on the network is performed only when the necessity is high.
  The invention according to claim 2 includes a plurality of wireless terminals that perform wireless data communication, and any of the wireless terminals can communicate with all other wireless terminals directly or via one or more other wireless terminals. In the wireless communication network system, the wireless terminal determines whether or not it is possible to adopt the communication path as a direct communication path by diagnosing the communication quality of the communication path directly communicating with other wireless terminals. Communication quality diagnosis means and presence notification means for notifying other wireless terminals of the presence of the communication quality diagnosis means, and the communication quality diagnosis means is notified by the presence notification means of the wireless terminal that is not directly communicable. It is characterized in that a communication path with a wireless terminal that is determined to be incapable of direct communication is determined when checking for a predetermined time or more or a predetermined frequency or more. With this configuration, only a highly reliable communication path is selected and used as a direct communication path, and a reliability diagnosis of the communication path that causes an increase in traffic on the network is performed only when there is a high necessity. To.
[0011]
  The invention according to claim 3 is the invention according to claim 1 or 2, wherein when the communication quality diagnosis unit re-determines a communication path determined in the past, the communication path that has been valid until now is used. Criteria used in diagnosisWhenJudgment criteria used for diagnosis of communication channels that were invalid until nowAnd set differentlyWith this configuration, an increase in traffic generated by notifying the entire system of a change in the communication path is reduced.
[0012]
  Claim4The invention described in claimAny one of 1 to 3In the invention described in the above, the communication quality diagnosis unit is configured such that the wireless terminal is normal by a sum of the number of specific data packets transmitted by the wireless terminal and the number of specific data packets transmitted by the other wireless terminal. A value relating to a ratio obtained by dividing the total of the number of data packets transmitted by the other wireless terminal received by the wireless terminal and the number of data packets transmitted by the wireless terminal normally received by the other wireless terminal. The reliability of the communication path is diagnosed by this configuration.
[0013]
  Claim5The invention described in claim4The specific data packet transmitted by the other wireless terminal has the number of specific data packets transmitted by the wireless terminal that is normally received by the other wireless terminal. Thus, the number of data packets received by the receiving wireless terminal is known.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1. Presence notification packet
FIG. 1 shows how wireless terminals C and I transmit presence notification packets in the wireless network system of FIG. The presence notification packet is a packet in which a unique code for identifying a wireless terminal that transmits the presence notification packet is stored, and has a structure shown in FIG. In the figure, reference numeral 1 indicates that this packet is a presence notification packet, and reference numeral 2 stores a code for identifying the wireless terminal that is the source of this presence notification packet.
[0017]
In FIG. 1, wireless terminals A, B, D, E, and F have the possibility of being able to communicate directly with wireless terminal C by receiving presence notification packets transmitted by wireless terminal C in the same manner. recognize. The wireless terminals F, G, H, and J recognize that they can communicate directly with the wireless terminal I by receiving the presence notification packet transmitted by the wireless terminal I.
[0018]
As described above, each wireless terminal A to J transmits the presence notification packet at a fixed period, thereby allowing each other to recognize the possibility of direct communication according to the radio wave propagation state at that time.
[0019]
However, the transmission timings of the presence notification packets may coincide with each other in a plurality of wireless terminals. In this case, the presence notification packet may not be received due to interference of radio waves transmitted by a plurality of wireless terminals, and there is a risk of misrecognizing that there is no possibility of direct communication.
[0020]
FIG. 3 shows an example of timing at which the wireless terminals A and B transmit the presence notification packet. In the figure, T is a cycle in which the wireless terminals A and B transmit the presence notification packet, tA is a timing at which the wireless terminal A transmits the presence notification packet, and tB is a timing at which the wireless terminal B transmits the presence notification packet. Each wireless terminal is determined so that tA and tB do not match, for example, by randomly selecting the transmission timing or by calculating the transmission timing from the serial number of each wireless terminal using the following formula. .
[0021]
Transmission timing = terminal serial number × (T / total number of terminals constituting the system)
In the above formula, when the terminal serial number includes non-numeric characters, it can be applied to the above formula using only the numeric part of the serial number, or can be applied one-to-one from the serial number. A function capable of obtaining a numerical value corresponding to is prepared in advance, and the numerical value obtained by this function may be substituted for the serial number of the terminal in the above equation.
[0022]
By the way, it is desirable to set the transmission cycle of the presence notification packet according to the traffic of normal communication on the network. In other words, the transmission cycle of the presence notification packet is preferably set long when the normal communication traffic on the network is dense, and conversely when the normal communication traffic on the network is not dense.
[0023]
In addition, if a sudden change in the network configuration is predicted due to changes in the surrounding environment where the system is installed, it is also convenient to set the transmission cycle of the presence notification packet so that it can quickly respond to the change. . In other words, if it is predicted that an environmental change that causes a change in the network configuration will occur suddenly, it is preferable to set the transmission cycle of the presence notification packet short.
[0024]
2. Communication path reliability diagnosis
In order for the wireless communication network system to automatically select the communication path and the relay route according to the communication quality at each time, the reliability of the communication path between each wireless terminal having the possibility of direct communication recognized by the presence notification packet. It is necessary to diagnose sex.
[0025]
FIG. 4 shows how the reliability of the communication channel AB is diagnosed. In the figure, the wireless terminal A performs a diagnosis on the communication path to the wireless terminal B. The wireless terminal A transmits a special packet (hereinafter referred to as a communication path diagnostic packet) for diagnosing the outgoing communication path to the wireless terminal B a total of N times, and the wireless terminal B that receives the packet transmits to the wireless terminal A Then, the communication path diagnosis packet for the return path is transmitted N times in total.
[0026]
The structure of the communication path diagnosis packet is shown in FIG. In this figure, 11 stores a code indicating that this packet is a communication path diagnosis packet and whether this communication path diagnosis packet is for the forward path or the return path, and 12 stores this communication path diagnosis packet. A code for identifying a wireless terminal that is a transmission source of the packet is stored, a code for identifying a wireless terminal that is a destination of the communication path diagnostic packet is stored in 13, and a communication that is transmitted to a communication path to be diagnosed is stored in 14. The total number of path diagnosis packets and a code indicating the number of communication path diagnosis packets to be transmitted for the communication path diagnosed by this packet are stored. Further, in the communication path diagnosis packet for return path, the number of communication path diagnosis packets for forward path normally received by the wireless terminal that transmits the communication path diagnosis packet is further stored in 15 of FIG.
[0027]
Returning to the description of FIG. When the wireless terminal B starts to receive the forward communication path diagnosis packet from the wireless terminal A, the wireless terminal B counts the number of times this forward communication path diagnosis packet is received. Further, the wireless terminal B calculates the time when transmission of all the forward communication path diagnostic packets by the wireless terminal A is completed from the total number of communication path diagnostic packets (14 in FIG. 5) stored in the forward communication path diagnosis packet. Then, after this time has elapsed, transmission of the return channel diagnostic packet to the wireless terminal A is started. The wireless terminal A calculates the time when transmission of all the return channel diagnosis packets by the wireless terminal B is completed from the total number of the channel diagnosis packets (14 in FIG. 5) stored in the return channel diagnosis packet, After this time has elapsed, the reliability of this communication path is calculated by the following equation.
[0028]
(Reliability) = (Number of normal round-trip receptions) / (Total number of round-trip communication path diagnostic packets)
The wireless terminal A is preset with a minimum value of reliability that can be used as a communication channel calculated by the above equation. If the calculation result of the above equation is larger than this minimum value, this communication channel is effective. Is determined.
[0029]
As described above, the reliability of the communication path is diagnosed (hereinafter referred to as “communication path diagnosis”). However, if the communication path diagnosis is frequently performed, traffic on the network is increased due to the diagnosis notification packet, and normal communication is performed. There is a risk of affecting. Therefore, it is desirable to perform the communication path diagnosis only when the necessity is considered high. An example of such a case is shown below.
[0030]
  FIG. 6 shows a state where the wireless terminal B receives the presence notification packet transmitted by the wireless terminal A. Same figureaShows that wireless terminals A and B can communicate in a normal state, but wireless terminal B misses the presence notification packet of wireless terminal A due to the influence of reflections by obstacles around the communication path. Show.
[0031]
In this case, the wireless terminal A also misses the presence notification packet transmitted from the wireless terminal B, and the wireless terminal A does not receive the presence notification packet from the wireless terminal B within a certain period (T in FIG. 3). Thus, the possibility that the reliability of the communication path with the wireless terminal B is lowered is recognized. However, since the presence / absence of the presence notification packet may occur even in a communication path with sufficient reliability, does wireless terminal A perform a communication path diagnosis on this communication path? Determine whether or not. For example, the wireless terminal A does not continuously receive the presence notification packet of the wireless terminal B for several cycles, or the reception rate of the presence notification packet of the wireless terminal B (the number of reception of the presence notification packet per unit time) is an allowable value. It is determined that the necessity of communication path diagnosis to the wireless terminal B is high by observing below, and as a result, the communication path diagnosis is performed.
[0032]
FIG. 6b shows a state where the wireless terminals A and B cannot communicate in the normal state but the wireless terminal B has received the presence notification packet of the wireless terminal A for some reason. This cause can also be affected by reflections by obstacles around the communication path. In this case, the wireless terminal A also receives an unscheduled reception of the presence notification packet transmitted from the wireless terminal B, and the wireless terminal A recognizes the possibility that the communication path to the wireless terminal B is valid. For example, the wireless terminal A receives the presence notification packet of the wireless terminal B continuously for several cycles, or diagnoses the communication path to the wireless terminal B when the reception rate of the presence notification packet of the wireless terminal B exceeds an allowable value. Recognizing the high degree of necessity, the communication path diagnosis to the wireless terminal B is performed.
[0033]
Note that the minimum reliability value that can be used as a communication path for use in communication path diagnosis is different between the diagnosis for the communication path that was valid until now and the diagnosis for the communication path that was invalid until now. Can be advantageous. In other words, if the minimum value of reliability that can be used as a communication path used for diagnosis on a communication path that has been valid up to now is set smaller than the value that is used for diagnosis on a communication path that has been invalid until now, The determination result of the communication channel diagnosis of the communication channel in the vicinity of the validity determination criterion does not frequently change. As will be described later, since it is necessary to notify the entire system of the change of the communication path, if the result of the communication path diagnosis does not change, the increase in communication traffic generated to notify the entire system of the change of the communication path is reduced. Effect is obtained.
[0034]
3. Managing system configuration information
Each wireless terminal needs to recognize through which wireless terminal having a direct communication path with all other wireless terminals constituting the system. Hereinafter, a method for managing the system configuration information by each wireless terminal will be described.
[0035]
FIG. 7 is a diagram for explaining a management method of system configuration information (related information) of the wireless terminal A in the present invention. This figure shows the system configuration information of the wireless terminal A in the configuration of the wireless communication network system shown in FIG.
[0036]
FIG. 7 shows the relationship between the number of communications performed until the packet transmitted by the wireless terminal A reaches the destination wireless terminal and the destination wireless terminal reaching the number of communications as the minimum number of communications. . From the figure, for example, it can be seen that there are B, C, and D as wireless terminals to which the wireless terminal A can transfer a packet in one communication, and also for transferring a packet including communication by a relay wireless terminal. It can be seen that there are E and F in wireless terminals that require at least two communications. Similarly, it can be seen that G, H, and I are available for wireless terminals that require at least 3 communications, and J is available for wireless terminals that require at least 4 communications.
[0037]
FIG. 8 shows configuration information of the wireless terminals B, C, and D that have a direct communication path with the wireless terminal A. The wireless terminal A manages the configuration information of the wireless terminals B, C, and D shown in FIG. 8 in addition to its own configuration information shown in FIG.
[0038]
As an example, consider a case where the wireless terminal A sends a packet to the wireless terminal E. Referring to FIG. 8, in order to transfer a packet to the wireless terminal E, it can be understood that the wireless terminal B can transfer the packet by one communication. Similarly, it can be understood that the data can be transferred from the wireless terminal C by one communication and from the wireless terminal D by two communication. As a result, the wireless terminal A sends a packet whose destination is the wireless terminal E to either the wireless terminal B or C.
[0039]
In the system configuration information management method according to the present invention, when a new communication path is set in the system or a communication path that has been valid until now becomes invalid, these are managed by each wireless terminal. You must update the configuration information. This method will be described next.
[0040]
It is necessary to notify the information regarding the change of the system configuration to all the wireless terminals constituting the system. Even if the system configuration is slightly changed, the configuration information is updated in a large amount in the entire system. If all of this work is performed simply by communication, there is a risk that very large traffic will be generated on the network. Therefore, the system configuration information is stored in the above-described presence notification packet so as to prevent an increase in traffic.
[0041]
FIG. 9 shows the structure of a presence notification packet that stores system configuration information. In the figure, parts having the same functions as those in FIG. The configuration information of the wireless terminal that transmits the presence notification packet is stored in 3 of FIG. For example, if the wireless terminal A sends the presence notification packet shown in the figure, the configuration information of the wireless terminal A shown in FIG. 7 is stored and sent in 3 of FIG.
[0042]
  FIG. 10 shows timings of various processes performed between the wireless terminal A and the wireless terminal B. In the figure, the wireless terminal A is in a receiving state in the interval T between transmission of the presence notification packets. The wireless terminal A receives and does not receive the presence notification packet from another wireless terminal in this interval T,a1It is determined whether or not the communication path diagnosis is performed at the timing of. As a result of the determination, when the communication path diagnosis is performed and the configuration information of the wireless terminal A is changed as a result of the diagnosis, the wireless terminal A is the next transmission timing of its own presence notification packet.a2, The presence notification packet storing the changed configuration information in 3 of FIG. 9 is transmitted. The wireless terminal A also transmits a presence notification packet storing the changed configuration information at subsequent transmission timings.
[0043]
On the other hand, the wireless terminal B receives the presence notification packet storing the changed configuration information of the wireless terminal A at the timing b1 in FIG. Here, the wireless terminal B detects a change from the configuration information of the wireless terminal A stored in the previously received presence notification packet, and further reflects the change in the configuration information of the wireless terminal B itself. The reconfiguration of this configuration information will be described next.
[0044]
  FIG. 11 shows a state in which the wireless terminal A edits the configuration information of the wireless terminals B, C, and D that have a direct communication path with itself. Same figureaIndicates the configuration information of the wireless terminals B, C, and D that have a direct communication path with the wireless terminal A that was initially managed, and is the same as FIG.
[0045]
  Here, it is assumed that, as a result of the wireless terminal A performing the communication path diagnosis on the wireless terminal E, it is determined that the communication path with the wireless terminal E that has been invalid is valid. The wireless terminal A adds and stores the received configuration information of the wireless terminal E to the configuration information of the wireless terminal having a direct communication path with itself. FIG. 11b shows the same figure.aThe configuration information of the wireless terminal E is added to FIG.
[0046]
  As another example, if the wireless terminal A performs a communication path diagnosis on the wireless terminal D and determines that the communication path with the wireless terminal D that has been valid so far is invalid, Terminal A managed the figureaThe configuration information of the wireless terminal D is deleted from each configuration information. Figure of deletion resultcShown in
[0047]
  FIG. 4D shows the case where the wireless terminal A detects a change in the configuration information of the wireless terminal D and is managed by the wireless terminal A.aThe example which updated the structure information of the radio | wireless terminal D from each structure information of these is shown. FIG. 6D shows the case where the wireless terminal D determines that the direct communication path with the wireless terminal H is valid.
[0048]
  Wireless terminal Ab-D is used to reconfigure the configuration information of the wireless terminal A. Here, the wireless terminal AbThe procedure for reconfiguring its own configuration information is described below.c, D is the same as the procedure for reconstructing the configuration information.
[0049]
  First, the wireless terminal A stores itself (wireless terminal A) in a row of wireless terminals to which the packet can be transferred by 0 communication. Next, the same figurebBy referring to the column with the number of communication times of 0, the wireless terminal A stores B, C, D, and E in the wireless terminal to which the packet can be transferred by one communication. Next, the figurebThe wireless terminal A transmits the packet by the communication of the wireless terminal A, B, C, D, E excluding the wireless terminals A, B, C, D, and E, which are already shown in the column of the communication number of 1 Store as a transferable wireless terminal. In the same way, the same figurebWireless terminals H, I, and J excluding the above-mentioned wireless terminals A to G from the wireless terminals shown in the column with the number of communication times of 2 can be transferred by the wireless terminal A in 3 communication times. Store as. When all wireless terminals constituting the system are set in this configuration information, the reconfiguration of the configuration information of the wireless terminal A is completed. The above figurebFIG. 12 shows the reconfiguration result of the configuration information of the wireless terminal A.
[0050]
Each wireless terminal updates the system configuration information managed by the procedure as described above, thereby preventing an increase in traffic on the network due to the system change. However, in this procedure, a certain amount of time is required until the update of the system configuration information of all the wireless terminals converges. Therefore, it is convenient to prepare a system configuration confirmation procedure corresponding to a case where confirmation of the system configuration is urgent even at the expense of some traffic increase, such as during system installation. This technique is described next.
[0051]
FIG. 13 shows the transmission timing of the presence notification packet of the wireless terminal A when the wireless terminal A is newly installed in the system. In the figure, the cycle Tn indicates the transmission timing of the presence notification packet at the normal time, and the cycle Tf indicates the transmission timing of the presence notification packet at the time of system installation. That is, when the system is installed, the transmission cycle of the presence notification packet is shortened.
[0052]
When a new wireless terminal A is additionally installed in this system, the wireless terminal A transmits a special presence notification packet. The structure of this special presence notification packet is shown in FIG. In the figure, parts having the same functions as those in FIG. Reference numeral 4 in FIG. 14 stores a code indicating that this presence notification packet is a transmission at the time of new installation.
[0053]
When the wireless terminal B receives this special presence notification packet transmitted by the wireless terminal A, the wireless terminal B reconfigures its own configuration information based on the configuration information of the wireless terminal A included in the presence notification packet, and Then, the presence notification packet storing the reconfigured configuration information and the flag indicating transmission at the time of new installation is also transmitted at the cycle Tf. The wireless terminal A receives the presence notification packet of the wireless terminal B, reconfigures its own configuration information, and stores the reconfigured own configuration information and a flag indicating transmission at the time of new installation. The presence notification packet is transmitted again with the period Tf. Thereafter, each wireless terminal repeats this procedure until the configuration information of each wireless terminal does not change. When the configuration information of this wireless terminal does not change even if the configuration information having this flag is received, the period is returned to Tn. The regular transmission state of the presence notification packet at the normal time without storing this flag is restored.
[0054]
With the method described above, changes in system configuration information can be transmitted to the entire system in a short time.
4). Forwarding communication packets
Based on the system configuration information managed by each wireless terminal described so far, a method for transferring an actual communication packet from a source wireless terminal to a destination wireless terminal will be described.
[0055]
FIG. 15 shows configuration information in the system of FIG. 50 managed by each of the wireless terminals A, B, E, and G. A procedure for transferring a communication packet from the wireless terminal A to the wireless terminal J will be described with reference to FIG.
[0056]
  The wireless terminal A configures the configuration information of the wireless terminals B, C, and D managed by itself (see FIG.a) To find the destination wireless terminal J. It can be seen that the wireless terminal J is located at the place where the number of communication is 3 from the wireless terminals B, C and D. Since the number of communication is the same regardless of which of the wireless terminals B, C, and D is transferred, the wireless terminal A arbitrarily selects a packet transfer destination. Here, it is assumed that B is selected.
[0057]
  The wireless terminal B configures the configuration information of the wireless terminals A, C, E managed by itself (see FIG.b) Find the destination wireless terminal J. It can be seen that the wireless terminal J is located at a place where the number of communications is 4 from the wireless terminal A, a place where the number of communications is 3 from the wireless terminal C, and a place where the number of communications is 2 from the wireless terminal E. Accordingly, the wireless terminal B transfers the packet to the wireless terminal E when it is determined that it is most efficient to transfer the packet having the wireless terminal J as the destination to the wireless terminal E.
[0058]
  Similarly, the wireless terminal E configures the configuration information of the wireless terminals B, C, F, and G managed by itself (see FIG.c) Find the destination wireless terminal J. The wireless terminal J has a place with the number of communication 3 from the wireless terminal B, a place with the communication number 3 from the wireless terminal C, a place with the communication number 2 from the wireless terminal F, and a place with the communication number 1 from the wireless terminal G. Therefore, the wireless terminal E transfers the packet having the wireless terminal J as the destination to the wireless terminal G.
[0059]
When the wireless terminal G receives a packet whose destination is the wireless terminal J, the wireless terminal J recognizes that the wireless terminal J is a wireless terminal capable of direct communication from the configuration information managed by the wireless terminal G (d in the figure), and transmits the packet. Transmit directly to wireless terminal J.
[0060]
The communication packet transmitted from the wireless terminal A arrives at the wireless terminal J by the procedure described above. FIG. 16 shows a communication path through which this communication packet is transferred.
By the way, when a packet is relayed in many stages in this way, the communication path may be temporarily interrupted due to a communication failure caused by an obstacle or the like, and the packet may not be transferred to the destination. In order to cope with such a case, when the packet is normally transferred between the respective direct communication paths, the wireless terminal that has received the packet transmits the packet to the wireless terminal that has transmitted the packet. It is better to send back a response indicating that it has been received. Hereinafter, a specific example in this case will be described.
[0061]
Consider a case where a communication failure occurs between the wireless terminals E and G during the transfer of the communication packet from the wireless terminal A to the wireless terminal J described with reference to FIG. FIG. 17 shows system configuration information managed by each of the wireless terminals E, F, and I in the system of FIG.
[0062]
  From FIG. 17 a, the wireless terminal E transfers the packet having the wireless terminal J as the destination to the wireless terminal G. However, here, it is assumed that a communication failure occurs and the wireless terminal E cannot confirm the packet reception response from the wireless terminal G. The wireless terminal E determines that a communication failure has occurred in the direct communication path to the wireless terminal G, and starts searching for another communication path. Same figureaAccordingly, the wireless terminal E transfers the communication packet to the wireless terminal F that is the next most efficient after the wireless terminal G in order to transfer a packet whose destination is the wireless terminal J. Hereinafter, the same figure managed by the wireless terminal F itselfbThe procedure for selecting the wireless terminal I from the configuration information and transferring the communication packet, and the wireless terminal I directly transferring the communication packet to the wireless terminal J is the same as described above. FIG. 18 shows the packet transfer path described here, and indicates that a communication failure has occurred in the communication path marked with a cross.
[0063]
The above procedure deals with temporary interruption of the packet relay route, but when such communication failures occur frequently in each communication channel, a packet sent once will be returned at a certain wireless terminal. There is.
[0064]
FIG. 19 shows a state in which communication failures frequently occur in each communication path in the system shown in FIG. In FIG. 19, the wireless terminal A transmits a communication packet for the wireless terminal J to the wireless terminal B (FIG. 21). The wireless terminal B transfers the packet to the wireless terminal E based on the configuration information managed by itself, but the transfer fails due to a communication failure between the BEs (FIG. 22). Therefore, the wireless terminal B transfers the communication packet to the wireless terminal C which is the second candidate for direct communication (FIG. 23). The wireless terminal C attempts to transfer to the wireless terminals E, F, and D, but any transfer fails (FIGS. 24, 25, and 26), and transfers the communication packet to the wireless terminal A (FIG. 27). Thereafter, this communication packet may continue to route between the wireless terminals A, B, and C unless the communication failure is resolved.
[0065]
In order to solve this problem, information for identifying each communication packet is stored in the packet. FIG. 20 shows an example of the structure of header information added to a communication packet. 41 shows a packet identification code attached to the wireless terminal that is the source of the communication packet, FIG. 42 shows a transmission identification code that shows the wireless terminal that is the source of the communication packet, and FIG. The incoming call identification code indicating the previous wireless terminal, the transfer source identification code indicating the transfer source wireless terminal of the communication path for transferring the communication packet in FIG. 44, and the communication packet transferred in FIG. The transfer destination identification code indicating the transfer destination wireless terminal of the communication path to be stored is stored.
[0066]
Further, each wireless terminal keeps a history of communication packets transferred by itself and their transfer destinations. When a communication packet from another wireless terminal is received, this communication packet is compared with the transfer history. If this communication packet was previously transferred by itself, this communication packet is The transfer destination and the transfer-destination wireless terminal that has transferred this communication packet at this time lower the priority of the transfer destination for this communication packet.
[0067]
Referring to the example of FIG. 19, the wireless terminal C returns the communication packet transmitted by the wireless terminal A (assuming that the packet identification code stored in the header information is n) to the wireless terminal A (FIG. 27). The wireless terminal A collates this communication packet with the transmission history of the past communication packet (FIG. 21), and finds that this communication packet has been sent to the wireless terminal B in the past. Therefore, the wireless terminal A searches for the destination wireless terminal J again from the configuration information of the system managed by itself, but this time, the wireless terminal B and the wireless terminal C are temporarily excluded and searched as the forwarding destination. Like that. Therefore, in this case, the wireless terminal A determines that it is most efficient to transfer the packet having the wireless terminal J as the destination to the wireless terminal D, and this packet is transferred to the wireless terminal D this time (in FIG. 19). 28). Thereafter, the communication packet is transferred to the wireless terminal J through the communication paths 29, 30, and 31 in FIG.
[0068]
By the way, the packet transfer destination wireless terminal on the direct communication path sends a reply indicating that the packet has been received to the transfer source wireless terminal, and the transfer source wireless terminal cannot receive this reply. The method for recognizing the temporary disruption of the road has been shown before, but the reason why the response cannot be received at the transfer source is due to a communication failure for only this response. In some cases, it can be received normally. In FIG. 22, the wireless terminal E transfers a communication packet from the wireless terminal A to the wireless terminal J to the wireless terminal G. The wireless terminal G normally receives this communication packet from the wireless terminal E and transfers it to the wireless terminal J, and returns to the wireless terminal E that the communication packet has been normally received. However, it is assumed that the wireless terminal E cannot normally receive this reply due to a communication failure suddenly occurring here. At this time, the wireless terminal E determines that the wireless terminal G cannot normally receive the communication packet, searches for another transfer path, and transmits the communication packet to the wireless terminal F. That is, here, a state occurs in which a plurality of identical packets exist on the network.
[0069]
In order to cope with this problem, the destination wireless terminal is configured to hold a communication packet incoming history. The incoming call history holds the packet identification code stored in the header information of the packet. In FIG. 22, the same packet is transferred from the wireless terminal F to the wireless terminal J via the wireless terminal I. The wireless terminal J has already received the packet from the packet identification code included in the header information of the packet. Recognize that the packet has already been discarded, and discard this packet. By doing so, the wireless terminal J prevents confusion due to arrival of a plurality of identical packets.
[0070]
The method for dealing with various communication failures described so far has been described for the case where there is at least one detour transfer route from the wireless terminal that is the source of the communication packet to the wireless terminal that is the destination of the communication packet. Due to a failure, this bypass route may not exist at all. Such an example is shown in FIG. In the figure, a communication packet having the wireless terminal J as a destination cannot be received. In this case, the communication packet continues to stray on the network. This state leads to an increase in traffic and may greatly affect other communications.
[0071]
In order to alleviate this problem, a counter that counts the number of times the communication packet is transferred is provided in the header information added to the packet. FIG. 24 shows an example of header information including this counter. In the figure, parts having the same functions as those in FIG. Reference numeral 46 in FIG. 24 stores a counter for counting the number of times the communication packet is transferred. Each wireless terminal that transfers a communication packet reads this counter value, and if this value is a value that is presumably set to be apparently straying (hereinafter, this value is referred to as the maximum number of transfers), This communication packet is discarded, otherwise, the counter value is updated by +1 and the transfer is continued. By doing so, a stray communication packet is surely discarded sometime, so that an increase in traffic on the network due to such a communication packet can be reduced.
[0072]
By using this counter, it is possible to limit the time for holding the transfer history / incoming history described above. The time until the same communication packet is discarded can be calculated by the following equation.
(Remaining time until packet discard) = {(Maximum number of transfers) − (Current counter value)} × (Time required for one transfer)
Therefore, after this time elapses, the transferred communication packet does not return, and the same communication packet as the incoming communication packet does not arrive again. Therefore, each wireless terminal transfers each communication packet. Along with the history / incoming history, the remaining time until the same communication packet is discarded is retained, and the history is discarded after the remaining time elapses. By doing so, it is possible to reduce the storage capacity of the storage device for holding the history, and it is also possible to reduce the time required for collating the newly received packet with these histories.
[0073]
5). Broadcast packet
Next, a method for efficiently transmitting the same information to a plurality of wireless terminals will be described.
[0074]
The communication packets described so far have been premised on a one-to-one communication in which only one terminal is a destination wireless terminal that finally receives the communication packet.
[0075]
In order to transmit the same transmission information to a plurality of wireless terminals using this communication packet, the wireless terminal that is the transmission information source has the same transmission information and stores different incoming call identification codes. It is necessary to transmit communication packets by the number of destination wireless terminals. The wireless terminal that relays the communication packet transfers the transferred communication packet to the destination or the wireless terminal that performs the next relay, and transmits a packet reception response to the transfer-source wireless terminal.
[0076]
Since such exchanges occur according to the number of communication packets transmitted from the source wireless terminal, the traffic on the network becomes very large, which is a problem.
[0077]
In order to solve this problem, a broadcast communication packet, which is a communication packet capable of storing a plurality of information on the destination wireless terminal, is introduced.
FIG. 25 shows an example of a broadcast packet structure. The broadcast packet is composed of header information 51, a destination ID part 52, and a transmission information part 53, as shown in FIG.
[0078]
In the header information 51, a broadcast packet identification code 54 indicating that this packet is a broadcast packet is stored at the head thereof. When this broadcast packet is used, a code indicating that this packet is a normal communication packet is also stored at the head of the normal communication packet so that both can be easily identified. It is convenient to do so.
[0079]
Further, the header information 51 also stores the same symbols 41 to 45 as those shown in FIG. These symbols are stored with the same contents as those in FIG. 20 unless otherwise specified.
[0080]
The destination ID unit 52 is a part that stores identification codes indicating all wireless terminals that are destinations for transmitting transmission information, and may have either structure shown in FIG.
In the figure, type 1 simply has an ID section 61 for storing an identification code of a wireless terminal as an information transmission destination. Type 2 has a structure in which an ID unit 61 and a check unit 62 that stores a check flag corresponding to the ID unit 61 exist.
[0081]
Although details will be described later, when the type 1 is used as the structure of the destination ID section 52, the stored identification codes of the wireless terminals are deleted one by one from the destination ID section 52 under certain conditions, and It will be excluded. Here, if the structure according to type 2 of FIG. 25B is used for the destination ID section 52, instead of deleting the identification code, the check section 62 corresponding to the ID section 61 in which the identification code is stored. A check flag is set to indicate that the destination is excluded from the designation.
[0082]
In the following description, it is assumed that type 1 is used as the structure of the destination ID section 52.
The transmission information unit 53 in FIG. 25A is a part that stores data to be transmitted to a plurality of wireless terminals.
[0083]
A method for transmitting information to a plurality of wireless terminals using the broadcast packet will be described. Here, a case where the wireless terminal A transmits the same information to all the other wireless terminals B to J in the system in the system of FIG. 50 will be described.
[0084]
The wireless terminal A has system configuration information shown in FIG. From this system configuration information, the wireless terminal A is the wireless terminal J that requires four times of communication among the wireless terminals of the destination to which the same information is transmitted and that requires the largest number of communication times to receive a communication packet. It can be recognized that there is. Therefore, the wireless terminal A stores the identification code indicating the wireless terminal J in the incoming call identification code 43 in the header information 51 of the broadcast packet shown in FIG. If there are many wireless terminals that are designated as destinations, there is a high possibility that the wireless terminal that relays the broadcast packet itself is designated as the destination of the broadcast packet. Good data packet delivery can be expected.
[0085]
Further, the wireless terminal A stores one identification code indicating the wireless terminals B to J that are destinations for transmitting the same information to each ID unit 61 in the destination ID unit 52 of the broadcast packet. FIG. 26 is a diagram illustrating a state in which the wireless terminal A stores an identification code indicating each wireless terminal in the broadcast communication packet. In addition, the destination ID part 52 shown to the same figure (b) uses the structure according to the type 1 of FIG.25 (b).
[0086]
On the other hand, in the other part of the header information 51 of the broadcast packet, the respective codes described so far are stored, and in the transmission information part 53, data to be transmitted to all wireless terminals constituting the network other than itself is stored. Is done.
[0087]
The wireless terminal A transmits a broadcast packet having the wireless terminal J generated as described above as a destination. This broadcast communication packet is assumed to arrive at the wireless terminal J via the communication path shown in FIG. 16 as a result, according to the communication packet transfer method described so far.
[0088]
The wireless terminal A transmits the generated broadcast packet to the wireless terminal B.
The wireless terminal B that has received the packet from the wireless terminal A checks the code stored at the head of the header information and recognizes that this packet is a broadcast communication packet. Before the broadcast packet is transferred to the wireless terminal E, the destination ID part 52 of the broadcast packet is checked, and it is searched whether or not an identification code indicating the wireless terminal B itself is stored in the destination ID part 52. To do.
[0089]
If an identification code indicating itself is detected as a result of the search, the wireless terminal B performs a process of receiving data stored in the transmission information part 53 of the broadcast packet. In order to prevent the data of the broadcast packet from being received again later, the broadcast packet from which the identification code indicating itself stored in the destination ID unit 52 is deleted is transferred to the next relay. It transmits to the wireless terminal E that is the destination.
[0090]
As a result of the search, if the identification code indicating itself is not detected from the destination ID unit 52, the wireless terminal B treats the broadcast communication packet in the following manner in the same manner as the transfer of the communication packet described above. Transmit to the wireless terminal E which is the relay destination.
[0091]
Thereafter, information reception processing similar to that performed by the wireless terminal B is performed by the wireless terminals F and G, and a broadcast communication packet in which the identification code indicating itself is deleted from the destination ID unit 52 is transmitted. Thereafter, the broadcast communication packet arrives at the wireless terminal J.
[0092]
The wireless terminal J performs the process of receiving the information stored in the transmission information portion 53 of the broadcast packet in the same manner as other wireless terminals, and replaces the wireless terminal J itself stored in the destination ID portion 52. The identification code shown is deleted. The contents of the destination ID portion 52 after deletion are shown in FIG. In the figure, the portion marked with x indicates that the identification code is deleted after being stored in the wireless terminal A.
[0093]
Next, the wireless terminal J has the largest number of wireless communication terminals until the communication packet is received from among the wireless terminal indicated by the identification code remaining in the destination ID portion 52 of the broadcast communication packet from the system configuration information that the wireless terminal J has. A wireless terminal requiring the number of communications is selected, and an identification code indicating the wireless terminal is stored in the incoming identification code storage unit 43 in the header information 51.
[0094]
FIG. 28 is a diagram illustrating system configuration information included in the wireless terminal J. From FIG. 27 and FIG. 27, the wireless terminal J is a wireless terminal that requires the largest number of communications before receiving a communication packet among the wireless terminals indicated by the identification codes remaining in the destination ID section 52. Select either C or D. It is arbitrary whether the wireless terminal J selects the wireless terminal C or the wireless terminal D. Here, it is assumed that the wireless terminal C is selected. The wireless terminal J stores the identification code indicating the wireless terminal C in the incoming call identification code storage unit 43 in the header information 51.
[0095]
The wireless terminal J transmits a broadcast communication packet having the wireless terminal C as a destination. This broadcast packet is assumed to arrive at the wireless terminal J via the communication path shown in FIG. 29 as a result of being transferred according to the transfer method described above. In the figure, a wireless terminal to which hatching is added indicates a wireless terminal that has already received the information stored in the transmission information part 53 of the broadcast packet.
[0096]
The wireless terminals I and F perform information reception processing similar to that of the wireless terminal B described above, and further transmit a broadcast packet in which the identification code indicating itself is deleted from the destination ID unit 52. Thereafter, the broadcast communication packet arrives at the wireless terminal C.
[0097]
Similarly to the wireless terminal J, the wireless terminal C performs information reception processing on the broadcast communication packet and deletes the identification code indicating the wireless terminal C itself stored in the destination ID unit 52. The wireless terminal that requires the largest number of communication times to receive the communication packet among the wireless terminals indicated by the identification code remaining in the destination ID portion 52 of the broadcast communication packet from the system configuration information that it has The wireless terminal H is selected, and the identification code indicating the wireless terminal H is stored in the storage unit 43 for the incoming identification code in the header information 51.
[0098]
The wireless terminal C transmits a broadcast communication packet having the wireless terminal H as a destination. This broadcast communication packet arrives at the wireless terminal H via the communication path shown in FIG. Similarly to FIG. 29, in FIG. 30, the wireless terminals indicated by hatching indicate wireless terminals that have already received the information stored in the transmission information part 53 of the broadcast packet.
[0099]
The wireless terminal C transmits a broadcast packet to the wireless terminal F.
The wireless terminal F that has received the broadcast packet searches for an identification code indicating the wireless terminal F itself in the destination ID section 52 of the broadcast packet.
[0100]
Since the broadcast packet has already arrived at the wireless terminal F before, the identification code indicating the wireless terminal F itself is deleted from the destination ID portion 52 of the broadcast packet at that time. In the search, the identification code indicating itself is not detected from the destination ID unit 52. Accordingly, the wireless terminal F does not perform the information reception process, and transmits the broadcast communication packet to the wireless terminal H that is the destination, in the same manner as the normal communication packet transfer described above.
[0101]
Similarly to the wireless terminal J, the wireless terminal H performs information reception processing on the broadcast communication packet and deletes the identification code indicating the wireless terminal H itself stored in the destination ID unit 52. Then, the wireless terminal D indicated by the identification code that is left only in the destination ID section 52 of the broadcast packet is selected, and the identification code indicating the wireless terminal D is stored in the storage section 43 of the incoming call identification code in the header information 51. Then, this broadcast communication packet is transmitted.
[0102]
The broadcast communication packet transmitted from the wireless terminal H arrives at the wireless terminal D again via the wireless terminal F, and the broadcast information packet transmitted from the wireless terminal A forms the system shown in FIG. Transmission to all wireless terminals is completed.
[0103]
As described above, it is possible to reduce network traffic that increases when the same information is transmitted to a plurality of wireless terminals.
By the way, in the method of transmitting the same information to the plurality of wireless terminals described so far, the wireless terminal that transmitted the broadcast packet has been able to receive the broadcast packet by all the destination wireless terminals. I can't confirm whether or not. The confirmation method will be described below.
[0104]
At the end of the above-described embodiment, when the wireless terminal D receives the broadcast communication packet, the wireless terminal D performs information reception processing in the same manner as the wireless terminal J, and an identification code indicating the wireless terminal D itself stored in the destination ID section 52 To be deleted. Then, by searching for the identification code remaining in the destination ID portion 52 of the broadcast packet and detecting that no identification code is left, the last time the broadcast packet was received by itself. The wireless terminal D can recognize that it is a wireless terminal. Therefore, the wireless terminal D transmits a packet notifying that the broadcast packet has been transmitted to all the wireless terminals designated as the destinations to the wireless terminal A that is the transmission source of the broadcast packet. .
[0105]
FIG. 31 is a diagram showing the contents of a communication packet transmitted by the wireless terminal D. The portion of the communication packet not shown in FIG. 31 has the same structure as the broadcast communication packet shown in FIG.
[0106]
The incoming call identification code storage section 43 in the header information 51 of FIG. 11A contains a transmission identification code storage section indicating the wireless terminal (radio terminal A in this embodiment) that is the source of the broadcast packet. The same identification code as the identification code stored in 42 is stored. Further, the destination ID section 52 in FIG. 5B keeps the state where all the identification codes indicating the destination wireless terminal of the broadcast communication packet are deleted. Although not shown in the figure, the transmission information portion stores the contents of the transmission information portion of the broadcast packet received by the wireless terminal D as it is. This broadcast communication packet is called a broadcast response packet.
[0107]
The wireless terminal D transmits the broadcast response packet to the wireless terminal A. In this embodiment, since packet transmission from the wireless terminal D to the wireless terminal A can be performed directly, the wireless terminal D transmits a broadcast response packet directly to the wireless terminal A.
[0108]
By receiving the broadcast response packet, the wireless terminal A can confirm that the broadcast packet has been transmitted to all the wireless terminals designated as destinations.
As described above, the wireless terminal that has transmitted the broadcast packet can confirm that the broadcast packet has been received by all the destination wireless terminals.
[0109]
Next, a description will be given of a method in which a wireless terminal that has transmitted a broadcast packet confirms the fact that the broadcast packet has not been transmitted to any of the wireless terminals designated as the destination.
[0110]
Reduce the traffic increase on the network by discarding the stray communication packet caused by the communication failure that occurred in the packet transfer route before the communication packet transfer count exceeds the predetermined number Explained. Here, this method is used.
[0111]
FIG. 32 is a diagram illustrating an example of a structure including a counter in header information of a broadcast communication packet. In the figure, reference numerals 41 to 45 and 54 are the same as those shown in FIG.
[0112]
The header information 51 of FIG. 32 further stores a counter 46 and a retry count 55. The counter 46 counts the number of times this broadcast packet is transferred, similar to that shown in FIG.
[0113]
The number of retries 55 stores the allowable number of retries for this broadcast packet (N is assumed here). Although this value can be arbitrary, increasing the value may increase communication traffic on the network. Decreasing the value may cause a communication path to a specific wireless terminal to be interrupted due to a temporary communication failure. Therefore, it is desirable to set an appropriate value in consideration of both.
[0114]
FIG. 33 shows a state where all communication paths to the wireless terminal H are interrupted during the transfer of the broadcast packet shown in FIG. 32 created by the wireless terminal A. This figure shows a state in which a communication failure has occurred during the transfer of the broadcast communication packet from the wireless terminal C shown in FIG.
[0115]
Since the wireless terminal F does not receive a response indicating that the packet from the wireless terminal H has been received after transmitting the broadcast packet to the wireless terminal H, the wireless terminal F recognizes that the packet transfer to the wireless terminal H has failed. Therefore, as described above, the wireless terminal F searches for a bypass communication path to the wireless terminal H via the wireless terminal I and transmits a broadcast communication packet to the wireless terminal I.
[0116]
The wireless terminal I transmits a broadcast packet to the wireless terminal H, but recognizes that the packet transfer to the wireless terminal H has failed in the same manner as described above, and bypasses the wireless terminal H via the wireless terminal F. The communication path is searched and a broadcast communication packet is transmitted to the wireless terminal F.
[0117]
The exchange of the broadcast packet is repeated, and eventually the counter 46 in the header information 51 of FIG. 32 reaches the maximum transfer count described above. Here, in the wireless terminal F, it is assumed that the counter 46 has reached the maximum number of transfers.
[0118]
Here, the wireless terminal F changes the broadcast packet whose destination is the wireless terminal H to a part of the data content of the broadcast packet without discarding it even when the counter 46 reaches the maximum transfer count. Add.
[0119]
The wireless terminal F examines the destination ID section 52 and arbitrarily selects one of the wireless terminals other than the wireless terminal in which the packet cannot be transferred among the wireless terminals from which the broadcast communication packet has not been received. The wireless terminal identification code is stored in the incoming call identification code storage unit 43 in the communication header information 51. At this time, it is possible to select a wireless terminal that requires the largest number of communication times to receive a packet among wireless terminals that have not received broadcast packets other than wireless terminals that cannot be transferred. Of course.
[0120]
At the same time, the wireless terminal F stores the initial value of the count in the counter 46 in the communication header information 51, and further changes the retry count 55 to a value obtained by subtracting 1 from the stored value. .
[0121]
FIG. 34 is a diagram showing the contents of the broadcast communication packet changed by the wireless terminal F.
The wireless terminal F selects the wireless terminal D that is left other than the wireless terminal H that cannot communicate from the destination ID section 52 of FIG. 7B, and receives the incoming call identification code as shown in FIG. The storage unit 43 stores the identification code of the wireless terminal D, the counter 46 stores “1”, which is the initial value of the count, and the retry count 55 is a value of (N−1). Storing.
[0122]
The wireless terminal F transmits to the wireless terminal D the broadcast communication packet in which part of the stored data content is changed as described above. In this way, even if there is a wireless terminal that cannot receive a broadcast packet due to a communication failure among the wireless terminals that are specified as the destination of the broadcast packet, to another wireless terminal that has no communication failure Can receive broadcast packets.
[0123]
The wireless terminal D performs information reception processing on the received broadcast communication packet, and deletes the identification code indicating the wireless terminal D itself stored in the destination ID section 52. Then, the wireless terminal H, which is the wireless terminal indicated by the single identification code remaining in the broadcast packet destination ID section 52, is selected, and the wireless terminal H is stored in the incoming identification code storage section 43 in the header information 51. Is transmitted to the wireless terminal F.
[0124]
Thereafter, the exchange of the broadcast packet with the wireless terminal H as the destination is repeated between the wireless terminal F and the wireless terminal I, and the counter 46 in the header information 51 of FIG. Reach the number of times. Here, in the wireless terminal I, it is assumed that the counter 46 has reached the maximum number of transfers.
[0125]
In the wireless terminal I, the data content stored in the broadcast packet is changed.
The wireless terminal I searches for a wireless terminal other than the wireless terminal H that cannot communicate from the destination ID unit 52 as in the case of the wireless terminal F before. Since there are no wireless terminals other than the wireless terminal H, the identification code of the wireless terminal H stored in the incoming identification code storage unit 43 is not changed. On the other hand, the counter 46 stores “1” which is the initial value of the count, and further stores the value of (N−2) obtained by subtracting 1 from (N−1) stored in the retry count 55. To do.
[0126]
Thereafter, the exchange of broadcast packets and the change of stored data with the wireless terminal H as the destination are repeated between the wireless terminal F and the wireless terminal I again. Eventually, in the wireless terminal F, it is assumed that the counter 46 of the broadcast packet whose value stored in the retry count 55 is “1” has reached the maximum transfer count.
[0127]
Since the result of subtracting “1” from the value stored in the retry count 55 is “0”, the wireless terminal F broadcasts to the wireless terminal H among the wireless terminals designated as destinations. A broadcast response packet notifying that the packet has not been transmitted is transmitted to the wireless terminal A that is the transmission source of the broadcast packet.
[0128]
FIG. 35 is a diagram showing the contents of a broadcast response packet transmitted from the wireless terminal F. Of the header information of the communication packet, the part not shown in FIG. 35A has the same structure as the header information of the broadcast packet shown in FIG. 32, and the other part of the communication packet is shown in FIG. It has the same structure as the broadcast packet shown.
[0129]
The incoming call identification code storage unit 43 in the header information 51 of FIG. 35A contains a transmission identification code storage part indicating the wireless terminal (radio terminal A in this embodiment) that is the source of the broadcast packet. The same identification code as the identification code stored in 42 is stored. Further, in the destination ID section 52 of FIG. 7B, only the identification code indicating the wireless terminal H that has failed to receive the broadcast packet is stored.
[0130]
Although not shown in the figure, the transmission information portion stores the contents of the transmission information portion of the broadcast packet received by the wireless terminal D as it is. Further, the value of the counter 46 may be arbitrary.
[0131]
The wireless terminal F transmits this broadcast response packet to the wireless terminal A.
By receiving this broadcast response packet, the wireless terminal A can confirm that the broadcast packet has not been transmitted to the wireless terminal H among the wireless terminals designated as destinations.
[0132]
As described above, when the broadcast packet is not transmitted to any of the wireless terminals designated as the destination, the wireless terminal that has transmitted the broadcast packet can confirm this, and which wireless terminal It is possible to confirm whether a broadcast packet has not been received.
[0133]
6). Missing wireless terminal detection
By the way, there may be a case where a wireless terminal such as the wireless terminal J in FIG. 23 or the wireless terminal H in FIG. 33 is lost due to a communication failure or a wireless terminal failure and is lost from the network. Explained earlier. Such a wireless terminal is hereinafter referred to as a missing wireless terminal.
[0134]
If a missing wireless terminal occurs in the wireless communication network, if the other wireless terminal can detect the fact of the occurrence and further which wireless terminal is the missing wireless terminal, for example, By notifying the user of the wireless terminal of the information, the user of the wireless terminal can recognize the necessity of eliminating the communication failure and repairing the wireless terminal, which is very convenient. Hereinafter, a method for detecting the missing wireless terminal will be described.
[0135]
A wireless terminal that detects a missing wireless terminal (hereinafter referred to as a detected wireless terminal) needs to know all the wireless terminals that make up the network. Information of all wireless terminals constituting this network is stored in advance in a storage element such as a ROM in an information form called an identification code of all wireless terminals, and the detection wireless terminal is provided with the storage element so that the information content can be used. Keep it.
[0136]
In addition, the detection wireless terminal is equipped with a flash memory or RAM, which is an electrically rewritable storage element, and the external storage device can be rewritten by connecting an external device such as a computer to the detection wireless terminal. And it is good also as a structure which gives the information to a detection radio | wireless terminal by writing the information of all the radio | wireless terminals which comprise a network from this external device in a memory | storage element. If the network configuration is frequently changed, the latter is more convenient because it saves the trouble of attaching and detaching the storage element each time the stored contents are changed.
[0137]
Furthermore, the presence notification described above is provided when it is confirmed that the detection wireless terminal has an electrically rewritable storage element and no missing wireless terminal is generated on the network immediately after the network is installed. The detection wireless terminal may acquire information of all wireless terminals constituting the network by packet transmission / reception and communication path diagnosis, and may write the information in a storage element that the detection wireless terminal has. This network configuration information acquisition function is executed by an instruction given from an external device connected to the detected wireless terminal, and when it is confirmed that a missing wireless terminal has not occurred on the network, this The command may be notified from the external device to the detection wireless terminal, which is convenient because the configuration wireless terminal information can be easily changed immediately after the network is changed.
[0138]
Assume that the network is configured as shown in FIG. 50, and the wireless terminal A is a detection wireless terminal. Of course, the detection wireless terminal is not limited to the wireless terminal A, and may be any wireless terminal configuring the network.
[0139]
The wireless terminal A is preliminarily given ten identification codes from the wireless terminal A to the wireless terminal J as information indicating all wireless terminals constituting the network.
Here, as shown in FIG. 36, consider a case where the wireless terminal J is missing from the network.
[0140]
On the network, transmission / reception of the presence notification packet described above and communication path diagnosis are performed, and the result is exchanged between the wireless terminals.
Then, in the wireless terminal A, system configuration information shown in FIG. 37 is created.
[0141]
Here, the wireless terminal A creates management information for all wireless terminals shown in FIG.
In FIG. 38, the horizontal axis of the table covers all the wireless terminals constituting the network, and indicates the wireless terminal that is the destination of the communication packet transmitted by the wireless terminal A. These fields are filled in based on information given in advance to the wireless terminal A.
[0142]
In the figure, the vertical axis of the table indicates that the left side is an adjacent wireless terminal capable of direct communication with the wireless terminal A, and the right side is required when a communication packet is transferred from the adjacent wireless terminal to the destination wireless terminal. The number of communications is shown respectively.
[0143]
In the figure, referring to the column of the wireless terminal B, “B, 0” is first written. This is because when the wireless terminal A sends a communication packet to the wireless terminal B, the wireless terminal B can directly communicate with the wireless terminal A. It shows that the number of communications after the wireless terminal B can be zero.
[0144]
“C, 1” is written in the column below the column “B, 0” of the wireless terminal B. This is because, when the wireless terminal A sends a communication packet to the wireless terminal B, first, when the communication packet is transferred to the wireless terminal C, the wireless terminal C of the communication packet from the wireless terminal A necessary to make the wireless terminal B receive the call. This indicates that the number of subsequent communications is one. Further, “D, 2” in the next column indicates the communication after the wireless terminal D of the communication packet from the wireless terminal A necessary for receiving the incoming call to the wireless terminal B when the communication packet is first transferred to the wireless terminal D. This indicates that the number of times is two.
[0145]
The contents of the above fields can be easily obtained by using the configuration information of the wireless terminal adjacent to the wireless terminal A among the system configuration information managed by the wireless terminal A shown in FIG.
[0146]
In this table, the communication count column is arranged in ascending order. The arrangement when the number of communication is the same may be arbitrary, but as a result of the communication path diagnosis performed previously, the communication paths may be arranged in descending order of reliability.
[0147]
In the table of FIG. 38 created as described above, the columns of the wireless terminal A and the wireless terminal J are all blank. This means that there is no communication route for receiving a communication packet from the wireless terminal A. Therefore, the wireless terminal J other than the wireless terminal A which is the own terminal may be a missing wireless terminal missing from the network. It can be detected by the wireless terminal A.
[0148]
The wireless terminal A includes a display device such as an LED. Here, the display of the missing wireless terminal in the network is displayed on the display device to notify the user of the wireless terminal, or the wireless terminal is connected to a computer or the like. If the external device is connected, the fact is notified. Further, the wireless terminal A displays the information of the missing wireless terminal detected in this way, for example, by displaying the identification code of the missing wireless terminal on the display device, or notifying the external device of information identifying the missing wireless terminal. Also good.
[0149]
Next, another method for detecting a missing wireless terminal will be described in the case where the network is in the state shown in FIG. Here again, the wireless terminal A is a detection wireless terminal.
First, as in the previous embodiment, the wireless terminal A is allowed to use the information of all wireless terminals constituting the network.
[0150]
On the network, transmission / reception of presence notification packets and communication path diagnosis are performed, and the wireless terminal A eventually has the system configuration information shown in FIG.
In FIG. 37, referring to the configuration information of the wireless terminal A, the wireless terminal A has the wireless terminals B, C, and D at the number of times of communication, the wireless terminals E and F at the number of times of communication of 3, and the It can be seen that the wireless terminals G, H, and I can communicate with each other by the number of times of communication.
[0151]
The wireless terminal A compares the information of each wireless terminal that can currently communicate with the information of all the wireless terminals that constitute the network, and determines that the wireless terminal J that does not match the information of both is a missing wireless terminal. . This determination result is displayed on the display device or notified to an external device, as in the previous example.
[0152]
The above-mentioned two methods detect the mismatch of the missing wireless terminal by detecting the coincidence or mismatch between the information of all the wireless terminals constituting the network and the information indicating the wireless terminals that can receive incoming communication packets. The same is true in determining occurrence.
[0153]
With the method for detecting missing wireless terminals described so far, it is possible to identify which wireless terminal is missing among the wireless terminals constituting the network. By the way, there is a simpler method if it is only intended to detect whether or not a missing wireless terminal is generated in the wireless terminals constituting the network.
[0154]
This method will be described with respect to the state of the network in FIG. As in the previous description, it is assumed here that the wireless terminal A is a detected wireless terminal.
The total number of wireless terminals constituting the network is given in advance to the wireless terminal A. In the example of FIG. 36, the total number of wireless terminals constituting the network is ten.
[0155]
On the network, the transmission / reception of the presence notification packet and the communication path diagnosis described so far are performed, and the wireless terminal A eventually has the system configuration information shown in FIG.
[0156]
Here, the wireless terminal A pays attention to the configuration information of the wireless terminal A itself among the configuration information of FIG. 37, and counts the number of destination wireless terminals shown there. From the figure, the number of 9 units from the wireless terminal A to the wireless terminal I is obtained.
[0157]
The wireless terminal A compares this number with 10 wireless terminals constituting the network given in advance, and as a result, it is found that the number of both does not match.
As a result, the wireless terminal A recognizes that a missing wireless terminal is generated on the network, displays the fact on the display device, and notifies the connected external device to that effect. At this time, the wireless terminal A indicates the shortage of the number of wireless terminals as destinations shown in the wireless terminal A of FIG. 37 with respect to the total number of wireless terminals constituting the network given in advance. Is also beneficial.
[0158]
7). Selection of detour transfer route of communication packet when communication failure occurs
Next, in a wireless communication network system, when a communication packet is transferred from the original wireless terminal to the final destination wireless terminal, an efficient detour transfer route in the event of a communication failure in the middle of the transfer route A selection method will be described.
[0159]
As a method of transferring a communication packet when a communication failure occurs in a communication path constituting a wireless communication network system, when a wireless terminal that has received the same communication packet as that transferred by itself retransmits this communication packet, this communication packet The method of lowering the priority at which both the wireless terminal of the transfer destination that forwarded the packet and the transfer source that forwarded the communication packet is selected as the wireless terminal that is the re-transfer destination of the communication packet was previously explained. This method is applied to a wireless communication network system having the configuration shown in FIG.
[0160]
39A, A to L indicate wireless terminals installed in a distributed manner, and solid lines in the figure indicate communication paths (hereinafter referred to as direct communication paths) through which the wireless terminals A to L can communicate directly. Show.
[0161]
In FIG. 39A, consider a case where the wireless terminal F transmits a communication packet having the wireless terminal L as the final destination. In this case, the wireless terminal F that is the transmitting wireless terminal is the method described so far as a relay wireless terminal for the communication packet (selects a terminal that can minimize the number of transfers among wireless terminals that can directly communicate with itself). Is used to select one of the wireless terminals I, J, and K.
[0162]
Next, as shown in FIG. 39B, due to an obstacle placed in the middle of the communication path, each of the radios FI, FJ, and FK in the direct communication path indicated by a solid line in FIG. Consider a case where the wireless terminal F transmits a communication packet having the wireless terminal L as the final destination when a communication failure occurs in the direct communication path between the terminals. In this case, the wireless terminal F selects any one of the wireless terminals A, B, C, and D as the relay wireless terminal.
[0163]
Even in the case shown in FIG. 39B, as a transfer route from the wireless terminal F to the wireless terminal L, a route (hereinafter referred to as a bypass route) that passes through the wireless terminals D, E, G, H, and K in order remains. It has been done. However, according to the above-described method, each wireless terminal selects a relay wireless terminal and transfers a communication packet so that the number of transfer times required until the wireless terminal L, which is a destination, receives a call is minimized. The possibility that the terminals A, B, C, and D select the wireless terminal F that is the transmitting wireless terminal as the relay wireless terminal and transfer the communication packet to the wireless terminal F is quite high. Therefore, the communication packet is transferred many times before the communication packet arrives at the wireless terminal L according to the above-described detour route, and as a result, the traffic on the network increases.
[0164]
According to the detour transfer route selection method described below, a communication route (a detour route) can be efficiently found instead of a normal communication route that cannot be communicated due to the occurrence of a communication failure, and communication packets can be transmitted using the detour route. Since the data can be transferred, it is possible to suppress an increase in traffic on the network when a communication failure occurs.
[0165]
In the following description, since the terms forward adjacent wireless terminal and backward adjacent wireless terminal are used, these will be described first.
FIG. 40 is a diagram showing the configuration information of each wireless terminal in the wireless communication network system of FIG. In FIG. 40, referring to the configuration information of the wireless terminal F that is the transmitting wireless terminal in the previous example, the wireless terminal that can receive a communication packet from the wireless terminal F by one communication, that is, the wireless terminal F It can be seen that wireless terminals having a direct communication path are A, B, C, D, I, J, and K. Hereinafter, these wireless terminals are referred to as adjacent wireless terminals.
[0166]
The wireless terminal F and each adjacent wireless terminal in the wireless terminal F compare the number of communications required until the wireless terminal L, which is the final destination of the communication packet in the previous example, receives the communication packet. Referring to FIG. 40, it can be seen that it takes two communication times for wireless terminal F, which is a transmitting wireless terminal, to receive a communication packet at wireless terminal L, which is a receiving wireless terminal. When the number of communications required for the wireless terminal L to receive a communication packet for each adjacent wireless terminal of the wireless terminal F is obtained from FIG. 40, the wireless terminals A, B, C, and D are three times more than the wireless terminal F. It can be seen that the number of communication times, and the wireless terminals I, J, and K are one communication number less than that of the wireless terminal F.
[0167]
In the above-described example, among the adjacent wireless terminals for a certain transmitting wireless terminal such as wireless terminals A, B, C, and D in the transfer of communication packets from the wireless terminal F to the wireless terminal L, the final destination An adjacent wireless terminal that requires more communication times than the wireless terminal to transfer a communication packet to the wireless terminal is referred to as a backward adjacent wireless terminal for the final destination wireless terminal in the source wireless terminal. In the example, the communication packet is transferred to the final destination wireless terminal among the adjacent wireless terminals for a certain wireless terminal, such as the wireless terminals I, J, and K in the transfer of the communication packet from the wireless terminal F to the wireless terminal L. An adjacent wireless terminal that requires fewer communication times than the wireless terminal is referred to as a forward-facing adjacent wireless terminal for the final destination wireless terminal in the source wireless terminal. .
[0168]
Note that although the wireless terminal F does not exist in the network shown in FIG. 39, the number of times of communication required to transfer a communication packet to the wireless terminal of the final destination among the adjacent wireless terminals of a certain outgoing wireless terminal is the wireless terminal. The adjacent wireless terminal having the same number as the number of communication required by the terminal is referred to as a laterally adjacent wireless terminal for the wireless terminal that is the final destination of the outgoing wireless terminal.
[0169]
In the following description of each configuration example of the network, it is assumed that the communication packet to be transferred is created by the wireless terminal F, but it is addressed to the wireless terminal L transferred from the other wireless terminal to the wireless terminal F. Even when the wireless terminal F transmits the communication packet for further transfer, the same detour transfer route selection method can be applied.
[0170]
Now, a method for selecting a detour transfer route according to the present invention will be described. Also in this case, in the wireless communication network system having the configuration shown in FIG. 39A, when a communication failure occurs in the direct communication path between the FI, FJ, and FK wireless terminals as shown in FIG. 39B. A case where the wireless terminal F transmits a communication packet having the wireless terminal L as the final destination will be described as an example.
[0171]
The wireless terminal F, which is a transmitting wireless terminal, manages its own system configuration information and the system configuration information of each adjacent wireless terminal for itself, in the same way as the management of the system configuration information by each wireless terminal described so far.
[0172]
In the network shown in FIG. 39A, the wireless terminal F, which is the originating wireless terminal, first sends a communication packet having the wireless terminal L as the destination to any of the wireless terminals I, J, and K that are forward-facing adjacent wireless terminals. Try to transfer. At this time, as shown in FIG. 39B, if a communication failure has occurred in the direct communication path between each of the FI, FJ, and FK wireless terminals, transfer is attempted for all of the wireless terminals I, J, and K. But everything fails.
[0173]
Next, the wireless terminal F tries to transfer a communication packet addressed to the wireless terminal L to the horizontally adjacent wireless terminal, but the wireless terminal F in the network shown in FIG. 39A does not have a horizontally adjacent wireless terminal. This transfer attempt is not made.
[0174]
Here, the wireless terminal F transmits the system configuration information about each adjacent wireless terminal managed by itself to the forward adjacent wireless terminal and the backward adjacent wireless terminal (hereinafter, referred to as the wireless terminal L that is the final destination of the communication packet). When the wireless terminal F is the source and the wireless terminal L is the final destination, the forward-facing adjacent wireless terminal is simply referred to as the forward-facing wireless terminal, the wireless terminal F is the source, and the wireless terminal L is the final destination The backward adjacent wireless terminal is simply classified as a backward wireless terminal.
[0175]
FIG. 41 is a diagram showing system configuration information managed by the wireless terminal F. FIG. 41 shows the system configuration information of each adjacent wireless terminal managed by the wireless terminal F: (A) configuration information of itself (wireless terminal F); (B) configuration information of backward wireless terminal; and (C) forward wireless. It is divided into terminal configuration information.
[0176]
Next, the wireless terminal F selects each of the adjacent wireless terminals that transfer packets first from the wireless terminal F from the system configuration information managed by itself shown in FIG. The frequency | count of communication performed after transmitting the communication packet addressed to a terminal from the wireless terminal F until it arrives at the destination wireless terminal is obtained for each adjacent wireless terminal. Then, the minimum number of times of communication for each destination wireless terminal is obtained in each of the backward wireless terminal and the forward wireless terminal classified earlier.
[0177]
FIG. 42 is a diagram illustrating the minimum number of times communication is performed before a communication packet transmitted from the wireless terminal F and addressed to each wireless terminal arrives at the destination wireless terminal. FIG. 3A shows the minimum number of times of communication with the destination wireless terminal when the backward facing wireless terminal is used for the first relay of the communication packet. Further, communication from the wireless terminal F to the destination wireless terminal is performed with the minimum number of communication times. Also shown is a backward-facing wireless terminal that may relay the communication packet first transmitted from the wireless terminal F when the packet arrives. FIG. 5B shows a case where the communication packet reaches the destination wireless terminal from the wireless terminal F with the minimum number of times of communication with the destination wireless terminal when the forward-facing wireless terminal is used for the first relay of the communication packet. 1 shows a forward-facing wireless terminal that may relay the communication packet first transmitted from the wireless terminal F.
[0178]
42 will be further described.
For example, a column in which the destination wireless terminal is the wireless terminal E is referred to.
Referring to FIG. 5A, when a communication packet addressed to the wireless terminal E is transmitted from the wireless terminal F to the backward wireless terminal, at least two communications are required until the communication packet arrives at the wireless terminal E. And when the communication packet arrives at the wireless terminal E with the minimum two communication times, the backward wireless terminal that may receive the communication packet first transmitted from the wireless terminal F may be received. It can be seen that only the wireless terminal D is present.
[0179]
On the other hand, in FIG. 5B, when a communication packet addressed to the wireless terminal E is transmitted from the wireless terminal F toward the forward-facing wireless terminal, at least four communications are required until the communication packet arrives at the wireless terminal E. And when a communication packet arrives at the wireless terminal E with the minimum number of four communication times, the forward-facing wireless terminal that receives the communication packet first transmitted from the wireless terminal F It can be seen that the terminals I, J, and K have the possibility.
[0180]
The wireless terminal F that has obtained the minimum number of times of communication with respect to each destination wireless terminal as shown in FIG. 42, here, until the communication packet is first transmitted to the backward wireless terminal (this is called backward transmission) The difference between the minimum number of communication required for the communication and the minimum number of communication required for the incoming call when the communication packet is first transmitted to the forward-facing wireless terminal (this is called forward transmission) is obtained for each destination wireless terminal. FIG. 43 is a diagram illustrating a difference in the minimum number of communication times required for a communication packet to arrive at each destination wireless terminal between backward transmission and forward transmission.
[0181]
Referring to FIG. 43, the difference in the minimum number of communication between the wireless terminal F that is the self terminal and the wireless terminal G that is not the self terminal is 0, and the minimum number of communication is set for the other destination wireless terminals. All the differences are 2. Like the wireless terminal G at this time, a destination wireless terminal whose difference in the minimum number of communication mentioned above is smaller than 2 except for the terminal itself is called a checkpoint.
[0182]
In this way, the presence of a checkpoint in the network means that the four terminals of the own terminal, any wireless terminal that is a forward adjacent wireless terminal, checkpoint, and any wireless terminal that is a backward adjacent wireless terminal are visited. It shows that a loop (ring) communication path exists in the network. This communication path is called a loop communication path.
[0183]
For example, when the loop communication path is a simple annular communication path that does not have a complicated communication path in the middle, and the above-described minimum communication count at the checkpoint is 0, the relay radio that configures the loop communication path This indicates that the number of terminals is an even number, and when the above-mentioned minimum communication count at the checkpoint is 1, it indicates that the number of relay wireless terminals constituting the loop communication path is an odd number. . When the number of relay wireless terminals constituting one loop communication path is an odd number, there are two check points on the loop communication path.
[0184]
On the other hand, if there is no relay wireless terminal having a minimum communication count of less than 2 other than its own terminal, that is, a checkpoint, the communication packet is transmitted from the transmitting wireless terminal by forward transmission or backward transmission. This indicates that when transferring to a relay wireless terminal, the outgoing wireless terminal must be routed in the middle of the communication packet transfer path, either forwardly or backwardly.
[0185]
Here, if a communication packet addressed to the destination wireless terminal is transmitted to the forward-facing adjacent wireless terminal, it is naturally impossible to pass through the transmitting wireless terminal in the middle of the transfer path. That is, in the above-mentioned case where the checkpoint does not exist in the network, even if a communication packet addressed to the destination wireless terminal is transmitted to the backward adjacent wireless terminal, the communication packet returns to the transmitting wireless terminal, and this transmitting wireless terminal This means that no incoming call arrives at the destination wireless terminal through another communication path without going through. Therefore, the backward transmission of the communication packet addressed to the destination wireless terminal in this case only causes an increase in traffic on the network, and the backward transmission of the communication packet to the adjacent wireless terminal is useless communication. I can say that.
[0186]
In view of this, when the destination wireless terminal whose minimum communication count is smaller than 2 is not present in the wireless terminals constituting the network other than the terminal itself, the transmitting wireless terminal does not perform backward transmission when a communication failure occurs. This is one of the features related to the present invention, which makes it possible to suppress an increase in traffic on the network when a communication failure occurs.
[0187]
Note that the search for the loop communication path so far has been performed after failing to transfer the communication packet to the forward and sideways adjacent wireless terminals. However, even if the search is performed in advance before attempting these transfers, No problem.
[0188]
The wireless terminal F checks the wireless terminal F from FIG. 43 obtained by the explanation so far, after trying to transfer all the wireless terminals I, J, and K to the wireless terminal L and failing to transfer the communication packet. By discovering that it is a point, it is recognized that a loop communication path exists in the network shown in FIG. Therefore, the wireless terminal F transmits a communication packet having the wireless terminal L as the destination, and tries to make the wireless terminal L receive the call via the wireless terminal G that is a checkpoint.
[0189]
As the transfer destination of the first communication packet by the transmitting wireless terminal at the time of backward transmission, a backward wireless terminal that reduces the number of communication times required to transfer the communication packet to the checkpoint is selected. Referring to FIG. 41B, the number of communications required to transfer a communication packet to the wireless terminal G that is the check point is the smallest when the wireless terminal D is selected from the backward wireless terminals, and is 2 less than the wireless terminal D. It can be seen that the communication packet can be transferred to the wireless terminal G by one communication. Therefore, the wireless terminal F transmits a communication packet to the wireless terminal D with the wireless terminal L as a destination and the wireless terminal G as a wireless terminal.
[0190]
The wireless terminal D that has received this communication packet has the least number of communications required to transfer the communication packet from the system configuration information that it has so far to the wireless terminal G that is the wireless terminal through which this communication packet passes. The adjacent wireless terminal for the wireless terminal D to be completed is selected. Here, the wireless terminal E is naturally selected, and the communication packet is transferred. Similarly, the wireless terminal E selects an adjacent wireless terminal as a transfer destination, and this communication packet is a via wireless terminal and arrives at the wireless terminal G that is a check point on the loop communication path.
[0191]
Here, consider the number of communications required to receive a communication packet from a checkpoint to a destination wireless terminal.
In this loop communication path, the wireless terminal that is the destination is branched from the wireless terminal that is in the middle of the communication path from the checkpoint to the source wireless terminal via the forward-facing wireless terminal. It is clear from the definition of the forward-facing wireless terminal that it exists on the communication path. Therefore, the communication path when the number of communications required to send a communication packet from the checkpoint to the destination wireless terminal is minimized is the destination via the checkpoint from the backward wireless terminal and the source wireless terminal. It is impossible to be a communication path for sending a communication packet to a wireless terminal, that is, a communication path that returns a communication path that has transferred the communication packet up to the checkpoint. This is the same even when any one of the wireless communication terminals constituting the loop communication path is arbitrarily selected and there are two checkpoints.
[0192]
Therefore, the transfer route of the communication packet from the check point to the final destination wireless terminal is the communication route that minimizes the number of communication required to send the communication packet from the check point to the destination wireless terminal as described above. Should be selected.
[0193]
The wireless terminal G, which is a via wireless terminal, refers to the system configuration information that it has described so far, and the number of communication required to transfer the communication packet to the wireless terminal L that is the final destination of this communication packet is the highest. An adjacent wireless terminal that can be reduced is selected, the final destination is the wireless terminal L, and the communication packet that is excluded from the designation of the wireless terminal via the wireless terminal G is transferred to the selected adjacent wireless terminal. It is obvious that the wireless terminal H is selected here.
[0194]
The flow in which communication packets are successively transferred after the wireless terminal H follows the communication packet transfer method described so far. This communication packet is transmitted from the wireless terminal H via the wireless terminal K to the final destination. An incoming call arrives at a certain wireless terminal L. FIG. 44 shows a detour route followed by a communication packet transmitted from the wireless terminal F and addressed to the wireless terminal L according to the above description.
[0195]
Thus, in a wireless communication network where a loop communication path exists, when a direct communication path to a forward-facing wireless terminal is interrupted due to a communication failure, the wireless terminal that transmits the communication packet transfers the communication packet to the backward-facing wireless terminal. Then, the communication packet is made to arrive at the final destination wireless terminal via the checkpoint. This is one of the features related to the present invention, and this feature enables efficient detour route selection when a communication failure occurs, thereby suppressing an increase in traffic on the network.
[0196]
In addition, when the number of wireless terminals constituting one simple annular loop communication path as described above is an odd number, and there are two checkpoints that satisfy the conditions described so far, one of them is selected. Can be arbitrarily selected as a wireless terminal via.
[0197]
Next, cases other than those described so far in which a plurality of checkpoints exist will be described.
FIG. 45 is a diagram illustrating an example of a configuration of a wireless communication network having a plurality of checkpoints. In the configuration of FIG. 39, among the wireless terminals constituting the network of FIG. 39A, a wireless terminal M having a direct communication path only with the wireless terminal G, and a wireless having a direct communication path only with the wireless terminal M. The terminal N is added to the structure shown in FIG.
[0198]
In FIG. 45, when the wireless terminal F transmits a communication packet whose final destination is the wireless terminal L, all of the wireless terminals G, M, and N satisfy the requirements for the checkpoints described so far. However, for example, when the wireless terminal M is used as a check point, it is obvious that communication packets reciprocate between the wireless terminals of the GM, and communication between the GMs is useless. It is obvious that the same communication occurs between the GM and MN wireless terminals even when a bypass route is obtained using the wireless terminal M as a checkpoint.
[0199]
In order to prevent wireless terminals such as wireless terminals M and N in FIG. 45 from being selected as checkpoints, wireless communication that satisfies the requirements for checkpoints described so far from the transmitting wireless terminal. Compare the minimum number of communications required to transfer to the terminal. Then, as a result of the comparison, the one with the smallest number of communications is set as a checkpoint. This is one of the features related to the present invention. In the example shown in FIG. 45, the number of communication required to transfer a communication packet from the wireless terminal F which is the transmitting wireless terminal is 3 times until the wireless terminal G, Since it is 4 times to the wireless terminal M and 5 times to the wireless terminal N, it is understood that the wireless terminal G may be selected as a checkpoint in this case. By doing so, the above-mentioned useless communication can be eliminated, and an increase in traffic on the network can be suppressed.
[0200]
When there are a plurality of checkpoints, in addition to the network configuration as shown in the example of FIG. 45, when the number of wireless terminals constituting one loop communication path is an odd number, or the loop communication path However, even in such a case, there is no particular problem even if the checkpoint is selected by the above-described method. In the case where there are a plurality of loop communication paths, there may be a plurality of the same number of communication times as described above, but in such a case, a checkpoint may be arbitrarily selected from those having the smallest number of communication times. .
[0201]
Next, a case where a wireless terminal that satisfies the checkpoint condition is inappropriate for use in selecting a bypass route will be described.
FIG. 46 is a diagram illustrating an example of a network configuration in which there are wireless terminals that are inappropriate for use in selecting a bypass route even though the checkpoint condition is satisfied. Comparing this figure with the network configuration example of FIG. 45, the wireless terminal E is lost and the communication between the wireless terminals DG has to go through the wireless terminal F, and the wireless terminal H is lost. The difference is that direct communication is possible between the wireless terminals GK.
[0202]
In FIG. 46, when the wireless terminal F transmits a communication packet having the wireless terminal L as the final destination, all of the wireless terminals G, M, and N satisfy the requirements for checkpoints described so far. Among these, the wireless terminal G is a wireless terminal that can receive a communication packet transmitted by the wireless terminal F, which is a transmitting wireless terminal, with the minimum number of communication times.
[0203]
By the way, the minimum number of communications required until the communication packet transmitted from the transmitting wireless terminal F is received by the wireless terminal L that is the final destination is two. On the other hand, the minimum number of communications required until the communication packet transmitted from the wireless terminal G is received by the wireless terminal L is also two. Accordingly, the wireless terminal G is a horizontally adjacent wireless terminal for the outgoing wireless terminal F.
[0204]
The detour route described so far is defined as a communication route in which a communication packet is always transferred from the originating wireless terminal to the backward wireless terminal first, and then transferred to the final destination wireless terminal via a checkpoint. Therefore, a communication path that does not pass through the backward wireless terminal that arrives at the wireless terminal L via the wireless terminals G and K from the wireless terminal F is not a bypass route. The wireless terminal F, which is the originating wireless terminal, tries to transfer to the backward wireless terminal first on the assumption that this bypass route is defined when transferring the communication packet by the bypass route, but does not pass through the wireless terminal F, which is the originating wireless terminal. Since there is no communication path through which the communication packet reaches the wireless terminal G from the backward wireless terminal, the communication packet eventually returns to the wireless terminal F, which is useless.
[0205]
In addition, since the transfer of the communication packet by the communication route having the wireless terminal G which is the horizontally adjacent wireless terminal as the first relay terminal is already attempted before the detour route search, the transfer should have failed. It is not always necessary to retry the communication path at this point.
[0206]
A wireless terminal that is inappropriate for use in selecting a detour route even though the checkpoint condition is satisfied, such as the wireless terminal G in FIG. 46, is hereinafter referred to as an inappropriate checkpoint.
[0207]
In order to detect an inappropriate checkpoint, the minimum number of communications required to transfer a communication packet to a wireless terminal that satisfies the above-mentioned checkpoint conditions is determined when the communication packet is transmitted from a backward-facing adjacent wireless terminal, Compare with the case of sending a communication packet from the terminal. If the minimum number of communications required to transfer a communication packet from the originating wireless terminal to the wireless terminal that satisfies the above checkpoint condition is smaller, the wireless terminal that satisfies the above checkpoint condition is an inappropriate checkpoint. Can be considered. This condition is easy considering that when a communication packet is transferred from a backward-facing adjacent wireless terminal to an unsuitable checkpoint that satisfies the checkpoint condition, it always passes through the originating wireless terminal in the middle of the communication packet transfer path. Understandable.
[0208]
When the above-described comparison is made with respect to the wireless terminal G in FIG. 46, the minimum number of communication required to transfer a communication packet from the wireless terminal F that is a transmission source to the wireless terminal G is one, and Since the minimum number of communications required to transfer a communication packet from the adjacent wireless terminal to the wireless terminal G is 2 in any of the wireless terminals A, B, C, and D, the wireless terminal G Can be excluded from the checkpoint. Similarly, the wireless terminals M and N are also found to be inappropriate checkpoints. Therefore, it can be seen that there is no checkpoint in FIG. 46, and the wireless terminal F does not have to transmit a communication packet to the backward adjacent wireless terminal.
[0209]
Note that if the above-described inappropriate checkpoint determination condition is applied to a checkpoint of a network where a detour route exists, the checkpoint may be determined to be an inappropriate checkpoint. Therefore, this determination condition needs to be considered as a kind of fail-safe that reliably prevents a communication packet from being transmitted to the backward adjacent wireless terminal even though there is no detour route. Therefore, for example, when it is known in advance that a detour route exists reliably, it is also useful not to perform the determination of the inappropriate checkpoint.
[0210]
Next, the structure of a communication packet used for selecting an efficient detour route described so far will be described with reference to FIG.
Each wireless terminal that has received the communication packet refers to 43 for storing the identification code of the destination wireless terminal, checks whether or not its own identification code is stored therein, and does not store its own identification code. Then, based on the system configuration information managed by itself, the operation of transferring this communication packet so as to arrive at the wireless terminal indicated by the identification code of the destination wireless terminal stored in 43 is now The same as above.
[0211]
On the other hand, if the identification code of the destination wireless terminal stored in 43 is its own, instead of immediately acquiring the stored transfer information, first, the identification code of the final destination wireless terminal is Reference 47 stored. If nothing is stored in 47 (null data), the wireless terminal that has received this communication packet is the final destination and acquires the stored transfer information. If the identification code of another wireless terminal is stored in 47, the wireless terminal that has received this communication packet recognizes that its own terminal is a transit wireless terminal (checkpoint) in the detour route, and Copy the stored identification code of the other wireless terminal to 43, which is the storage position of the identification code of the destination wireless terminal, and store null data in 47, based on the system configuration information managed by itself, This communication packet is transferred so as to arrive at the wireless terminal indicated by the identification code of the destination wireless terminal stored in 43.
[0212]
A state in which the header information of the communication packet is changed in the course of the detour route from the wireless terminal F to the wireless terminal L in the wireless communication network shown in FIG. 39B will be described with reference to FIG.
[0213]
First, the wireless terminal F attempts to transfer to the forward wireless terminals I, J, and K in order to make the wireless terminal L receive the communication packet storing the header information shown in FIG. As shown in FIG. 6A, at this time, 43 stores the identification code of the wireless terminal L that is the final destination, and 47 is null data.
[0214]
When the wireless terminal F that has failed to transfer all of the communication packets to the forward wireless terminals I, J, and K due to a communication failure finds a detour route by the above-described method, the header information of the communication packet is shown in FIG. Change as shown and forward to wireless terminal D. In the header information of the communication packet at this time, the identification code of the wireless terminal L, which is the final destination, stored in 43 in FIG. The identification code of the wireless terminal G that is a terminal) is stored.
[0215]
The communication packet transferred to the wireless terminal D then passes through the wireless terminal E and arrives at the wireless terminal G that is a checkpoint.
When the wireless terminal G detects that the identification code indicating itself is stored in 43, 47 is checked, and it is detected that the identification code of the wireless terminal L is stored in 47. As a result, the wireless terminal G recognizes that this communication packet is transferring a detour route, and that its own terminal is a checkpoint on the detour route. Then, the header information of the communication packet is copied to 43 as the identification code of the wireless terminal L stored in 47 as shown in FIG. The wireless terminal G transfers this communication packet to the wireless terminal H in order to receive the communication packet at the wireless terminal L indicated by the identification code stored in 43.
[0216]
Thereafter, the communication packet transferred to the wireless terminal H arrives at the wireless terminal L via the wireless terminal K.
The wireless terminal L refers to the header information of the communication packet shown in FIG. 5C, stores the identification code indicating its own terminal in 43, and detects that 47 is null data. And the transfer information stored in the communication packet together with the header information is acquired.
[0217]
In FIG. 47, null data is not stored in 47, but the identification code of the final destination wireless terminal is always stored. In checkpoint identification, the identification code of its own terminal is stored in 43, and 47, it is detected that an identification code not belonging to the own terminal is stored, and the identification code of the own terminal is stored in both 43 and 47 in identifying the final destination wireless terminal. This may be detected.
[0218]
Further, instead of providing a storage field for the identification code of the final destination wireless terminal in the header information of the communication packet, a storage field for the identification code of the via wireless terminal is provided and stored. If the identification code storage column is always referred to and the identification code is stored in this storage column, the identification code is not stored in this storage column and the data is null data. In this case, the communication packet may be transferred to the destination wireless terminal. In this case, when the via wireless terminal detects an identification code indicating its own terminal in the storage column of the identification code of the via wireless terminal, the transit wireless terminal performs an operation of clearing the storage column to obtain null data. .
[0219]
As described above, it is possible to transfer the communication packet by following the detour route of the communication packet by having information on the wireless terminal to be passed through the communication packet and transferring the communication packet through the wireless terminal actually indicated by the information. This is one of the features related to the present invention.
[0220]
Next, when a communication packet is transferred using a bypass route, a countermeasure when a communication failure occurs in the bypass route will be described with reference to FIG.
The configuration of the communication network in the figure is the same as that of the network shown in FIG.
[0221]
As shown in FIG. 49, a communication packet addressed to the wireless terminal L from the wireless terminal F is being transferred to the wireless terminal L via the detour route due to a communication failure in each of the direct communication paths of FI, FJ, and FK. Now, let us consider a case where transfer of a communication packet fails due to a communication failure caused by an obstacle even in a direct communication path from the wireless terminal E to the wireless terminal G.
[0222]
In the header information of the communication packet received by the wireless terminal E from the wireless terminal D, the identification code of the wireless terminal G is stored in 43, and the identification code of the wireless terminal L is stored in 47, as shown in FIG. ing. When the wireless terminal E detects that the identification information stored in 43 and 47 indicates different wireless terminals, the communication packet is in the process of being transferred to the checkpoint via the detour route. Recognize
[0223]
Here, the wireless terminal E attempts to make the communication packet arrive at the wireless terminal L that is the final destination of the communication packet regardless of the detour route. That is, the header information of the communication packet is copied to 43 as the identification code indicating the wireless terminal L, which is the final destination, stored in 47 as shown in FIG. Then, based on the system configuration information managed by the wireless terminal E itself, the communication packet is transferred so as to arrive at the wireless terminal L.
[0224]
As described above, when a communication packet is transferred using the detour route, even when a communication failure occurs in the detour route, the transfer of the communication packet toward the wireless terminal that is the final destination of the communication packet is continued. be able to.
[0225]
After this, if the influence of the communication failure is received before the incoming call to the wireless terminal L, the method of selecting the detour route described so far will be used again by the wireless terminal that has recognized the transfer failure. Obviously.
[0226]
【The invention's effect】
As described above in detail, according to the present invention, each process of installation investigation, system design, installation work, system configuration change work, and maintenance work can be easily performed, and further, generation of useless communication can be reduced on the network. There is an effect that it is possible to provide a wireless communication network system that suppresses an increase in traffic as much as possible.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a state in which wireless terminals C and I transmit presence notification packets.
FIG. 2 is a diagram illustrating a structure of a presence notification packet.
FIG. 3 is a diagram illustrating a timing at which wireless terminals A and B transmit a presence notification packet.
FIG. 4 is a diagram showing a state of diagnosing the reliability of a communication channel AB.
FIG. 5 is a diagram illustrating a structure of a communication path diagnosis packet.
6 is a diagram illustrating a state in which a wireless terminal B receives a presence notification packet transmitted from a wireless terminal A. FIG.
7 is a diagram illustrating a method for managing system configuration information of a wireless terminal A. FIG.
FIG. 8 is a diagram illustrating configuration information of wireless terminals B, C, and D having a direct communication path with the wireless terminal A managed by the wireless terminal A;
FIG. 9 is a diagram illustrating the structure of a presence notification packet that stores system configuration information.
FIG. 10 is a diagram illustrating timings of various processes performed between the wireless terminal A and the wireless terminal B.
FIG. 11 is a diagram illustrating a state in which the wireless terminal A edits the configuration information of the wireless terminals B, C, and D that have a direct communication path with itself.
12 is a diagram showing a result of reconfiguration of configuration information of a wireless terminal A. FIG.
FIG. 13 is a diagram illustrating the transmission timing of the presence notification packet of the wireless terminal A when a wireless terminal A is newly installed in the system.
FIG. 14 is a diagram illustrating a structure of a special presence notification packet storing a flag indicating that transmission is performed at the time of new installation.
FIG. 15 is a diagram illustrating configuration information managed by each wireless terminal A, B, E, and G;
FIG. 16 is a diagram showing a packet transfer path from the wireless terminal A to the wireless terminal J;
FIG. 17 is a diagram illustrating configuration information managed by each wireless terminal E, F, and I;
FIG. 18 is a diagram illustrating a packet transfer path from the wireless terminal A to the wireless terminal J when a communication failure occurs in the communication path EG;
FIG. 19 is a diagram illustrating a communication packet transfer path when communication failures occur frequently in each communication path;
FIG. 20 is a diagram illustrating an example of a structure of header information added to a communication packet.
FIG. 21 is a diagram illustrating an example of a transmission history held by the wireless terminal A.
FIG. 22 is a diagram illustrating a state in which there are a plurality of communication packets on the network.
FIG. 23 is a diagram illustrating a state in which a communication packet strays when communication failures frequently occur on a communication path.
FIG. 24 is a diagram illustrating an example of the structure of header information including a counter added to a communication packet.
FIG. 25 is a diagram illustrating the structure of a broadcast packet.
FIG. 26 is a diagram illustrating a state where the wireless terminal A stores an identification code indicating each wireless terminal in the broadcast packet.
FIG. 27 is a diagram showing the contents of a destination ID portion in a broadcast packet at wireless terminal J.
FIG. 28 is a diagram showing system configuration information possessed by a wireless terminal J.
FIG. 29 is a diagram illustrating a packet transfer path from the wireless terminal J to the wireless terminal C;
30 is a diagram illustrating a packet transfer path from the wireless terminal C to the wireless terminal H. FIG.
FIG. 31 is a diagram showing the contents of a broadcast response packet transmitted by the wireless terminal D.
FIG. 32 is a diagram illustrating an example of a structure including a counter in header information of a broadcast communication packet.
FIG. 33 is a diagram illustrating a state in which all communication paths to the wireless terminal H are interrupted during transmission of a broadcast communication packet.
FIG. 34 is a diagram showing the contents of a broadcast communication packet changed by the wireless terminal F.
FIG. 35 is a diagram showing the contents of a broadcast response packet transmitted by the wireless terminal F.
36 is a diagram showing a state where a wireless terminal J is missing from the network shown in FIG. 50. FIG.
FIG. 37 is a diagram showing configuration information managed by the wireless terminal A in FIG. 36.
FIG. 38 is a diagram showing management information of all wireless terminals managed by the wireless terminal A in FIG.
FIG. 39 is a diagram for explaining how the wireless terminal F selects a bypass transfer route.
40 is a diagram showing configuration information of each wireless terminal in the wireless communication network system of FIG. 39 (A).
41 is a diagram showing system configuration information managed by a wireless terminal F. FIG.
FIG. 42 is a diagram showing the minimum number of communications that are performed before a communication packet transmitted from the wireless terminal F and destined for each wireless terminal arrives at the destination wireless terminal.
FIG. 43 is a diagram illustrating a difference in the minimum number of communication times required for a communication packet to arrive at a destination wireless terminal between backward transmission and forward transmission.
44 is a diagram illustrating a detour route followed by a communication packet transmitted from the wireless terminal F and addressed to the wireless terminal L. FIG.
FIG. 45 is a diagram illustrating an example of a configuration of a wireless communication network having a plurality of checkpoints.
FIG. 46 is a diagram illustrating an example of a network configuration in which there is a wireless terminal that is inappropriate for use in selecting a bypass route even though the checkpoint condition is satisfied.
FIG. 47 is a diagram illustrating a structure of a communication packet for performing efficient detour transfer route selection.
FIG. 48 is a diagram illustrating a state in which header information stored in a communication packet is changed.
FIG. 49 is a diagram illustrating a countermeasure when a communication failure occurs in a bypass route.
FIG. 50 is a diagram illustrating an example of a configuration of a wireless communication network system.
[Explanation of symbols]
A to N Wireless terminal
T Cycle at which each wireless terminal transmits a presence notification packet
a1, a2, b1 timing
tA Timing at which wireless terminal A transmits a presence notification packet
tB Timing at which wireless terminal B transmits the presence notification packet
1 Code indicating that this packet is a presence notification packet
2 Code that identifies the wireless terminal that sent this presence notification packet
3 Configuration information of the wireless terminal that transmits this presence notification packet
4 Code indicating that this presence notification packet is transmitted when newly installed
11 A code indicating that this packet is a communication path diagnosis packet and whether this communication path diagnosis packet is for the forward path or the return path
12 Code for identifying the wireless terminal that is the source of this communication path diagnostic packet
13 Code identifying the wireless terminal that is the destination of this channel diagnosis packet
14 A code indicating the total number of communication path diagnosis packets to be transmitted to the communication path to be diagnosed and the number of the communication path diagnosis packets transmitted for the communication path to be diagnosed
15 Number of outgoing path diagnostic packets normally received by the wireless terminal that transmits this diagnostic packet
21-31 communication path
41 Packet identification code attached by the wireless terminal that is the source of the communication packet
42 Transmission identification code indicating the wireless terminal that is the source of the communication packet
43 Incoming call identification code indicating the destination wireless terminal of the communication packet
44 Transfer source identification code indicating the transfer source wireless terminal of the communication path for transferring the communication packet
45 Transfer destination identification code indicating the transfer destination wireless terminal of the communication path for transferring the communication packet
46 Counter for counting the number of times this communication packet is transferred
47 Final incoming call identification code indicating wireless terminal of final destination of communication packet
51 Header information
52 Destination ID part
53 Transmission information section
54 Broadcast Packet Identification Code
55 Retry count
61 ID part
62 Check section

Claims (5)

In a wireless communication network system configured by a plurality of wireless terminals that perform wireless data communication, any of the wireless terminals can communicate with all other wireless terminals directly or via one or more other wireless terminals,
The wireless terminal has communication quality diagnosis means for determining whether or not the communication path can be adopted as a communication path for direct communication by diagnosing the communication quality of the communication path for direct communication with other wireless terminals ; A presence notification means for notifying the wireless terminal of its presence,
The communication quality diagnosing unit is a wireless terminal that is capable of direct communication when the notification by the presence notification unit of the wireless terminal that is directly communicable is not confirmed for a predetermined time or more or a predetermined frequency. Determine the communication path between
A wireless communication network system. In a wireless communication network system configured by a plurality of wireless terminals that perform wireless data communication, any of the wireless terminals can communicate with all other wireless terminals directly or via one or more other wireless terminals,
The wireless terminal has communication quality diagnosis means for determining whether or not the communication path can be adopted as a communication path for direct communication by diagnosing the communication quality of the communication path for direct communication with other wireless terminals; A presence notification means for notifying the wireless terminal of its presence,
The communication quality diagnosing means is connected to the wireless terminal that is not capable of direct communication when confirming the notification by the presence notification means possessed by the wireless terminal that is not directly communicable for a predetermined time or more or a predetermined frequency. Determine the communication path between,
A wireless communication network system. The communication quality diagnostic means, to re-determine the communication path determined in the past, the decision criteria used in diagnostics for the effective a communication path ever used in diagnostics for the channel was ineffective until now The wireless communication network system according to claim 1, wherein the determination criterion to be set is different . The communication quality diagnosing means is the sum of the number of specific data packets transmitted by the wireless terminal and the number of specific data packets transmitted by the other wireless terminal, and the other received normally by the wireless terminal. Determining based on a value relating to a ratio obtained by dividing a total of the number of data packets transmitted by a wireless terminal and the number of data packets transmitted by the wireless terminal normally received by the other wireless terminal The wireless communication network system according to any one of claims 1 to 3 . 5. The radio according to claim 4 , wherein the specific data packet transmitted by the other radio terminal has the number of specific data packets transmitted by the radio terminal normally received by the other radio terminal. Communication network system.

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