JP2007266876A - Wireless communication method, wireless communication device, and wireless communication program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless communication technology for efficiently achieving multi-casting communication of high reliability. <P>SOLUTION: The wireless communication method is that a destination node which has been able to receive a multi-casting packet retransmits the packet to a destination node which has not been able to receive the packet. It includes: a step that the destination node which receives the multi-casting packet transmits a reception report (ACK); a step that a node which receives the reception report transmits a non-reception report (NACK) when the node does not receive the packet corresponding to the reception report; and a step that a destination node which receives the non-reception report, transmits the packet requested retransmission. It is desirable that the node which receives the non-reception report retransmits the packet reported as a non-reception packet after a predetermined period elapses from reception of the non-reception report. Further it is desirable that the own node stops retransmission when another node performs retransmission of the packet during the interval. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to wireless communication technology.

  Conventionally, in the wireless communication system of the IEEE 802.11 system, the receiving node has not transmitted ACK (Acknowledgements) reporting that it has received the broadcast data of the transmitting node. This is to avoid congestion caused by a plurality of nodes that are broadcast data destinations returning ACKs simultaneously. However, the sender could not detect that there was a node that could not receive the broadcast data and could not retransmit it. Therefore, there is no method for a node that has not received broadcast data to regain data that has not been received.

  Patent Documents 1 and 2 describe techniques for retransmitting (transferring) broadcast data in a wireless communication system using road-to-vehicle communication and vehicle-to-vehicle communication. In the techniques described in Patent Literatures 1 and 2, a vehicle that has received broadcast data from a roadside device transmits the information to surrounding vehicles through inter-vehicle communication. Vehicles that could not receive broadcast data from roadside aircraft can use the data transmitted by inter-vehicle communication to obtain broadcast data even when direct communication with roadside aircraft is not possible. It becomes possible to do.

  Patent Document 3 discloses a technology that uses road-to-vehicle communication and vehicle-to-vehicle communication, and receives broadcast data from surrounding vehicles from surrounding vehicles through vehicle-to-vehicle communication when road-to-vehicle communication is interrupted. Is described.

  Non-Patent Document 1 and Patent Document 4 describe a technique in which a node that has not received broadcast data transmits a NACK (Negative Acknowledgement) to request retransmission. Specifically, the node that receives the broadcast data transmits ACK. Then, a node that has received ACK from surrounding nodes but has not received broadcast data detects that its own node has not received the broadcast data. The node that has detected that broadcast data has not been received in this way transmits a NACK to the transmission source node, and requests retransmission of the broadcast data.

As described above, various techniques for reliably transmitting broadcast data to a destination node have been proposed.
JP 2004-38244 A JP 2004-139510 A JP 2000-322690 A JP 2000-115051 Yoko Utsunomiya, Masaki Hiroshiro, Satoshi Hirose, “MAC protocol using broadcast data retransmission by NACK and directional antenna in wireless ad hoc network”, IEICE Transactions, Vol.J-87B, No.2, pp .144-158, February 2004

  However, in the case of the prior art as described above, the following problems have occurred.

  First, in the methods described in Patent Documents 1 and 2, since the node (vehicle) that receives the broadcast data always transmits the data to the surrounding nodes, a lot of useless communication occurs and the communication efficiency is improved. It will decline.

  Moreover, in the technique of patent document 3, when the road-to-vehicle communication becomes out of communication, the structure switched to vehicle-to-vehicle communication is taken. In order to detect the disconnection of road-to-vehicle communication, it is necessary to be able to communicate with a roadside machine once. Therefore, for example, a vehicle that cannot establish communication with a roadside device once, such as a vehicle hidden behind a large vehicle, cannot detect that communication with the roadside device has been interrupted. As a result, switching to inter-vehicle communication cannot be performed, and broadcast data cannot be obtained from the roadside machine.

  The techniques described in Non-Patent Document 1 and Patent Document 4 do not cause the above problems. That is, since ACK, which is a short packet, is only transmitted after the broadcast data is received, consumption of the communication band is minimized. In addition, it is a case where the own node has not established communication with the sending node of the broadcast data because it has detected that the own node has not received the broadcast data by ACK from another receiving node. It is also possible to request retransmission.

  However, the techniques described in Non-Patent Document 1 and Patent Document 4 have the following problems. A non-reception node that has not received broadcast data from the transmission node transmits a NACK (non-reception report) to the transmission node, but there is no guarantee that this NACK will reach the transmission node. Even if the NACK reaches the transmitting node, there is no guarantee that the retransmitted broadcast data will reach the unreceived node. In particular, considering that the first broadcast data did not reach the unreceived node, there is an obstacle (such as a large vehicle) on the communication path, or the node itself cannot communicate with the transmitting node in radio waves. It may be in a positional relationship. In such a case, even if an unreceived node can detect that its own node has not received broadcast data by ACK from surrounding nodes, it cannot acquire broadcast data from the transmitting node by retransmission.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a technique for efficiently realizing highly reliable broadcast communication.

  In order to achieve the above object, in the present invention, broadcast data is transmitted by the following means or processing. In the wireless communication method according to the present invention, a destination node that can receive a packet addressed to a plurality of destination nodes transmits the packet to a destination node that cannot receive the packet (both as a proxy for retransmission or a transfer). This is a wireless communication method. Packets destined for a plurality of destination nodes include, for example, broadcast packets destined for all nodes in the network and multicast packets destined for nodes belonging to a predetermined group (multicast group). Hereinafter, a packet destined for a plurality of destination nodes is referred to as a broadcast packet.

  In the wireless communication method according to the present invention, the destination node that has received the broadcast packet transmits a reception report notifying that the packet has been received. The reception report includes information for specifying the received packet.

  The reception report is received by a surrounding node that has transmitted the reception report. The node that has received the reception report determines the type of broadcast packet corresponding to the received reception report. When the local node is included in the destination of the broadcast packet corresponding to the received reception report and the local node has not received the broadcast packet, the fact that the broadcast packet has not been received is notified. Send an unreceived report. The unreceived report includes information for specifying a packet that could not be received.

The destination node that has received the unreceived report transmits a broadcast packet corresponding to the unreceived report. As a result, a node that has not received the broadcast packet can acquire the broadcast packet. That is, the destination node that has received the unreceived report has proxyed the retransmission of the broadcast packet. Hereinafter, in this specification, it is also referred to as “retransmission” that a node different from the packet transmission source node acts as a proxy (or forwards or relays) retransmission of the packet.

  Thus, in the wireless communication method according to the present invention, a node that has not received a broadcast packet can detect that the broadcast packet has not been received only by a surrounding reception report. That is, it is possible to detect that the broadcast packet has not been received even before communication with the transmission node of the broadcast packet is established.

  Further, the node that retransmits the broadcast packet is not limited to the transmission source node. In other words, even if there is a shielding object between the sending node and the non-receiving node of the broadcast packet, and these nodes cannot communicate, receive this broadcast packet from other nodes. Is possible.

  Further, since the broadcast packet is retransmitted only when there is a node that cannot receive the broadcast packet, useless communication can be avoided and efficient communication can be performed.

  In the wireless communication method according to the present invention, it is preferable that a node that has received an unreceived report transmits a broadcast packet corresponding to the unreceived report after a predetermined period has elapsed after receiving the unreceived report. . In this case, if another node transmits a broadcast packet before the own node transmits the broadcast packet, the own node preferably stops transmitting the broadcast packet. When the neighboring nodes retransmit the broadcast packet, it is considered that further retransmission is unnecessary, and thus the retransmission can be stopped to reduce the communication amount.

  The predetermined period (standby time) is preferably set so that a node suitable for retransmission is shorter depending on the situation. For example, it is preferable to shorten the standby time as the reception strength of the unreceived report is stronger because a node having a stronger reception strength of the unreceived report has a better communication state with the unreceived node. Further, since a node having higher transmission capability is a node suitable for retransmission, it is preferable to shorten the standby time as the transmission capability of a node that has received an unreceived report is higher. When the destination of the broadcast packet is specified as a node within a predetermined range, a node suitable for retransmission can be determined based on the position information. For example, when the broadcast packet service area is narrower than the communicable range of each node, the node located at the center of the service area can be said to be a node suitable for retransmission. Further, when the broadcast packet service area is larger than the communicable range of each node, a node far from the broadcast packet transmission node can be said to be a node suitable for retransmission. Thus, it is also preferable that the waiting time is determined based on the position information of the node that has received the unreceived report. Note that the determination of the standby time may be a combination of the above methods.

  Note that the present invention can be understood as a wireless communication apparatus that executes at least a part of the above processing. Further, the present invention can be understood as a program for realizing the above processing. Each of the above means and processes can be combined as much as possible to constitute the present invention.

For example, as one aspect of the present invention, a wireless communication apparatus includes: a packet receiving unit that receives a packet that is destined for a plurality of destination nodes; a reception report unit that transmits a reception report that notifies that the packet has been received; When the reception report is received from the node of the node, if the own node is included in the destination of the packet corresponding to the reception report and the node has not received the packet, the packet has not been received. And a non-reception report means for transmitting a non-reception report for notifying a non-reception report, and a packet transmission means for transmitting a packet corresponding to the non-reception report when the non-reception report is received from another node. To do.

  According to another aspect of the present invention, a wireless communication program transmits, to a wireless communication apparatus, packet reception means for receiving a packet addressed to a plurality of destination nodes, and a reception report notifying that the packet has been received. When a reception report is received from a reception report means and another node, the packet corresponding to the reception report includes the own node, and if the own node has not received the packet, the packet A non-reception report means for transmitting a non-reception report for notifying that it has not received, a packet transmission means for transmitting a packet corresponding to the non-reception report when receiving a non-reception report from another node, It is a program to make it function as.

  According to the present invention, it is possible to efficiently realize highly reliable broadcast communication.

  Exemplary embodiments of the present invention will be described in detail below with reference to the drawings.

(First embodiment)
The first embodiment of the present invention is wireless communication in an ad hoc wireless network composed of movable wireless communication devices. An ad hoc wireless network is an autonomous wireless network that is temporarily constructed by mobile terminals without depending on infrastructure such as a base station or a dedicated line. When direct communication (one-hop communication) is not possible, such as when the distance between nodes is long, information is exchanged by relaying nodes existing on the way and performing multi-hop communication. In this embodiment, broadcast communication is performed within an ad hoc wireless communication network.

  In the wireless communication device according to the present embodiment, an arithmetic unit such as a CPU, a main storage device such as a RAM, and an auxiliary storage device such as a ROM are configured via a bus, and a program stored in the auxiliary storage device is stored in the main storage device. And the following processing is performed by the CPU. In addition, all or some of the functions of the wireless communication device in the present embodiment may be configured by a dedicated chip.

FIG. 1 is a sequence diagram showing a procedure for performing broadcast communication. FIG. 2 is a diagram for explaining communication performed in each process. First, the node S transmits a broadcast packet (S01, FIG. 2 (a)). The broadcast packet stores information such as a transmission node ID, information type, and information transmission target. In the information transmission target, a value indicating broadcast is stored when this communication is broadcast. When this communication is broadcast, a network ID, ESSID (Extended Service Set ID), or the like may be stored. In the case of multicast transmitted to nodes belonging to a predetermined group, an ID indicating the multicast group is stored.

  The nodes a and b that have normally received the broadcast packet transmit ACK (reception report) notifying that the broadcast packet has been received (S02, FIG. 2B). As the ACK, a pulse signal having a characteristic corresponding to the type of the received broadcast packet is used. For example, it is conceivable to use a pulse signal that uses a specific frequency (subcarrier in OFDM (Orthogonal Frequency Division Multiplexing)) according to the type of information.

The ACK is received not only by the node S that is a transmission node of the broadcast packet but also by surrounding nodes. Processing performed by the node that has received the ACK will be described with reference to the flowchart of FIG. FIG. 3 is a flowchart of processing for determining whether or not the own node has not received a broadcast packet based on ACK.

  First, nodes around the node that transmitted the ACK receive the ACK (S10). The node that has received the ACK determines whether or not the broadcast packet corresponding to the ACK has been received (S11). Since ACK is a pulse signal having characteristics according to the type of broadcast packet, a node that has received ACK can make this determination. If the corresponding broadcast packet has been received (S11—YES), the process ends because there is no need to send an unreceived report. When the corresponding broadcast packet has not been received (S11-NO), it is determined whether or not the local node is included in the destination of the broadcast packet (S12). Since the node that has received the ACK knows the type of the corresponding broadcast packet by the ACK, the destination node of the broadcast packet can also be determined. Here, if the broadcast packet corresponding to ACK is not destined for the own node (S12-NO), the own node does not need to acquire the broadcast packet, and the process ends. When the corresponding broadcast packet includes its own node as the destination (S12-YES), a NACK (unreceived report) notifying that this broadcast packet has not been received is transmitted (S13). NACK is also a pulse signal having a characteristic corresponding to the type of broadcast packet, similar to ACK. Therefore, the node that has received the NACK can determine which broadcast packet the NACK transmitting node has not received. Note that the order of the determination processing of S11 and S12 may be switched.

  Returning to the description of FIGS. The ACK transmitted by the nodes a and b in S02 is received by the node c. The node c that has received the ACK has not received the broadcast packet corresponding to the ACK, and knows that this broadcast packet is broadcast and includes its own node as a destination, and therefore transmits a NACK (S03). FIG. 2 (c)). The nodes a and b also receive the ACK transmitted from the nodes b and a, respectively, but do not transmit a NACK because the corresponding broadcast packet has already been received.

  The NACK transmitted by the node c is received by the nodes a, b, and S that are surrounding nodes. Processing performed by the node that has received NACK will be described with reference to the flowchart of FIG. FIG. 4 is a flowchart of processing for retransmitting a packet when a NACK is received.

  First, nodes around the node that transmitted the NACK receive the NACK (S20). Next, the node that has received the NACK obtains the time to wait before resending (S21). In the present embodiment, each node stores a standby time predetermined according to the NACK reception strength as a table, and acquires the standby time based on the table. The standby time is shorter as the NACK reception strength is higher. The node that has received NACK waits for this predetermined waiting time (S22). After the waiting time elapses, it is determined whether the local node has received the broadcast packet requested to be retransmitted (S23). That is, it is determined whether another node has retransmitted during the standby time. If the node has received a broadcast packet that has not been reported yet (S23-YES), it is determined that there is no need to retransmit, the packet retransmission is stopped, and the process is terminated. If the node has not received a broadcast packet that has not been reported yet (S23-NO), the broadcast packet is retransmitted (S24).

Returning to the description of FIGS. The NACK transmitted by the node c in S03 is received by the nodes a, b, and S. Here, it is assumed that the NACK reception strength at node b is the strongest. Therefore, node b has the shortest waiting time until retransmission. In this case, the node b having the shortest waiting time first transmits the broadcast packet requested to be retransmitted (S04, FIG. 2 (d)). This retransmission packet is received not only by the node c but also by the nodes a and S. Since the nodes a and S can detect that another node has retransmitted during the waiting time by receiving the retransmission packet, the nodes a and S stop the retransmission of the packet (S05). The node c that has received the retransmission packet does not particularly transmit ACK or the like. If node c does not receive a packet after a predetermined period of time despite having transmitted NACK, node c transmits NACK again.

  According to this embodiment configured as described above, a broadcast packet can be retransmitted to a node that has been designated as the destination node of the broadcast packet but has not received the broadcast packet. It becomes possible. In addition, since retransmission is performed only when a NACK is received, when there is no node that has not received a broadcast packet, retransmission is not performed and occurrence of unnecessary communication can be suppressed.

  In addition, since any of the nodes that received the broadcast packet can act as a proxy for retransmission, even if communication between the source node and the unreceived node is impossible, the broadcast packet is relayed by other nodes. Can be received. At that time, a predetermined standby time is provided before retransmission, and a node suitable for retransmission is shortened so that a node optimal for retransmission can perform retransmission.

  Note that the wireless communication method used in this embodiment can efficiently perform flooding for transmitting packets to all nodes in the ad hoc wireless network. That is, a node that is two hops away from the flooding transmission source node can receive an ACK from the one hop ahead node of the transmission source. Therefore, the 2-hop destination node can request packet transfer (relay) to the 1-hop destination node by transmitting NACK. In this way, by using NACK to request transfer from a node that has not received a packet, the packet is distributed to all the nodes in the ad hoc wireless network. Since the transfer is requested from the node that could not receive the packet, the transfer is not performed when there is no node that could not receive the packet, and the amount of communication can be reduced. By providing the waiting time as described above when transferring according to NACK, it is possible to avoid duplication of transmission and allow an optimum node to perform relaying.

(Second Embodiment)
The second embodiment of the present invention is an Advanced Cruise-Assist Highway System (AHS) composed of a roadside device (base station) and a vehicle (a wireless communication device mounted on the vehicle). The present embodiment is a system that supports the prevention of a collision by notifying a vehicle existing around an intersection or the like from a roadside machine.

  A system overview of the present driving support road system is shown in FIG. In the present driving support road system, the roadside machine 10 prevents the collision of the encounter by notifying the vehicles on the secondary roads joining the priority roads of the presence of the vehicles 18 on the priority roads. The roadside machine 10 transmits information to the vehicles in the service providing area 11 on the secondary road all at once (broadcast transmission). A vehicle traveling on a secondary road detects a service-in to the service providing area 11 by passing through a base beacon area 13 that is a range in which a beacon from the base beacon 12 can be received. Information from the base point beacon 12 includes information such as the service target vehicle, the ID and position of the roadside device 10, the type of service, and the service provision range.

The radio wave transmitted from the roadside device 10 is designed to reach the communicable range 14 when there is no obstacle. Since the service providing area 11 is included in the communicable range 14, normally, a vehicle located in the service providing area 11 can receive information from the roadside machine 10. However, as shown in the figure, when there is a large vehicle 16 in the service providing area 11, the large vehicle 16 becomes a shield, and the radio waves transmitted from the roadside machine 10 reach only the communicable range 15. A situation that does not occur may occur. Even when there is no shielding object on the communication path, the radio wave environment may be deteriorated due to the effect of multipath fading, and the radio wave arrival range from the roadside device 10 may be narrowed. In these cases, the vehicle 17 in the service providing area 11 cannot receive information from the roadside machine 10.

  Also in the present embodiment, a vehicle that has not been able to acquire information from the roadside machine 10 receives information by receiving a retransmission from the vehicle that has been able to acquire the information by the same communication procedure as in the first embodiment. That is, the vehicle that has received information from the roadside device 10 transmits an ACK notifying that the information has been received. This ACK is received by vehicles around the vehicle that transmitted the ACK. The vehicle that has received the ACK has not received the information corresponding to the ACK, and if this information includes the own vehicle as a destination (the own vehicle is a service target vehicle), this information NACK notifying that it has not been received is transmitted. The vehicle that has received the NACK transmits information from the roadside device 10 after a predetermined waiting time. In this way, when a vehicle that has received information from the roadside device 10 using NACK retransmits, even a vehicle that cannot receive radio waves from the roadside device 10 due to the influence of the shielding object is transmitted from the roadside device 10. Information can be acquired. The information transmitted by the roadside machine 10 may be retransmitted not only by the vehicle that received the information but also by the roadside machine 10 itself.

  It is preferable that the waiting time from when the NACK is received until the information is retransmitted is designed so that the waiting time of the vehicle or the roadside device suitable for the retransmission is shortened. FIGS. 6 to 8 are tables defining the priority of retransmission (the higher the value, the higher the priority). The higher the retransmission priority, the shorter the waiting time is set.

  FIG. 6 is an example in which the retransmission priority is defined according to the signal strength of the received NACK. The higher the NACK reception strength, the higher the priority. This is because the radio wave environment between vehicles with strong received radio wave strength is stable, and thus a vehicle with strong NACK reception strength is considered suitable for retransmission.

  FIG. 7 is an example in which retransmission priority is defined according to the type of vehicle (including a roadside device) that has received NACK. As shown in FIG. 7, priority is given in the order of roadside machine, truck, van, sedan, and mini. This is because a larger vehicle has a wider radio wave transmission range and is considered suitable for retransmission.

  FIG. 8 is an example of defining the retransmission priority based on the distance from the base beacon of the vehicle that has received the NACK. As shown in FIG. 8, the higher the retransmission priority is set, the closer the vehicle is to the center of the service providing area. This is because if the vehicle located at the center of the service providing area performs retransmission, it is considered that the retransmitted information reaches the entire service providing area.

  Further, in the present embodiment, the retransmission priority is determined by the above three methods, the sum of the three priorities is taken, and the standby time is determined based on the total value. The correspondence between the total value of the three priorities and the standby time is, for example, as shown in FIG. As shown in FIG. 9, the standby time is set shorter as the total value of the three priorities is larger. That is, the standby time becomes shorter as the vehicle is more suitable for retransmission.

  A method of calculating the standby time will be specifically described with reference to FIG. As shown in FIG. 10, vehicles A1, A2, A3, A4, and X1 exist in the service providing area of the roadside machine R. Although the vehicles A1 to A4 have been able to receive information from the roadside machine R, the vehicle X1 has not been able to receive. Therefore, the vehicle X1 determines that the vehicle has not received the information from the roadside device R by ACK from another vehicle, and transmits NACK. This NACK is received by the vehicles A1 to A4 and the roadside machine R, and the waiting time is calculated in each vehicle and roadside machine. Note that the NACK reception intensity, the distance from the base beacon, and the type (vehicle type) of the vehicles A1 to A4 and the roadside device R are as shown in the figure.

  As shown in FIG. 11, each vehicle and roadside device first calculates retransmission priority according to the NACK reception strength, the distance from the base beacon, and the type. For example, since vehicle A1 has a received intensity of −70 dB, the corresponding priority is 3, and the distance from the base point beacon is 0.9L, so the corresponding priority is 5, and the type is a track, so the corresponding priority. Is calculated as 9. The total of these priorities is 17, and based on the table of FIG. 9, it is calculated that the standby time is 20 milliseconds. Similarly, for vehicle A3, the priority corresponding to the NACK reception intensity is 8, the priority corresponding to the distance from the base beacon is 9, and the priority corresponding to the type is 9. Accordingly, the total priority of the vehicle A3 is 26, and the standby time is calculated as 5 milliseconds. Thus, the standby time of the vehicle A2 is calculated as 10 milliseconds, and the standby time of the vehicle A4 is calculated as 40 milliseconds. Further, the waiting time of the roadside machine R is calculated as 20 milliseconds.

  The vehicle that has received NACK waits for the waiting time calculated in this way, and then retransmits the information received from the roadside device R. Further, when another vehicle (roadside machine) performs retransmission within the standby time, the retransmission is stopped in order to prevent the retransmission from being repeated. By such a method, a vehicle having the highest priority, that is, a vehicle most suitable for retransmission can be retransmitted.

  Note that the calculation method of the priority and the standby time is an example, and the priority and the standby time may be calculated by any method as long as the calculation is performed so that the vehicle standby time suitable for retransmission is shortened. May be. For example, the information used as the criterion for determining the priority may be a relative speed between vehicles other than information such as NACK reception strength, transmission capability, and position in a service area. This is because communication between vehicles having a small relative speed is considered to be relatively stable. The relative speed may be acquired by exchanging the speed (speed and direction) of each vehicle by communication, or by determining the influence of the Doppler effect from the waveform of the received NACK signal. good.

  In addition, the standby time is determined based on the total value of each priority determined based on the above three information (reception strength, transmission capability, position information). It may be determined on the basis of any one priority. In addition, when summing the priorities, a weighted sum may be calculated instead of simply summing.

It is a sequence diagram of communication performed when resending broadcast data. It is a figure for demonstrating the communication performed at the time of resending of broadcast data. It is a flowchart of the process which determines whether a self-node has not received broadcast data based on the received ACK. It is a flowchart of the process which resends broadcast data based on the received NACK. It is a figure which shows the system configuration | structure of a driving assistance road system. It is a figure which shows the example of the table which defines resending priority. It is a figure which shows the example of the table which defines resending priority. It is a figure which shows the example of the table which defines resending priority. It is a figure which shows the example of the table showing the relationship between resending priority and standby | waiting time. It is a figure which shows the example of the positional relationship of the vehicle in a driving assistance road system. It is a figure explaining the calculation method of waiting time.

Explanation of symbols

S broadcast packet transmission node a, b, c node 10 roadside machine 12 base point beacon 16,17 vehicle

Claims (8)

A wireless communication method in which a destination node that can receive a packet having a plurality of destination nodes as destinations transmits the packet to a destination node that cannot receive the packet,
A destination node that has received a packet addressed to a plurality of destination nodes transmits a reception report notifying that the packet has been received;
The node that received the reception report does not receive the packet when the node corresponding to the reception report includes the node itself and the node does not receive the packet. Sending an unreceived report to notify
A destination node that has received the unreceived report transmits a packet corresponding to the unreceived report;
A wireless communication method comprising:   2. The wireless communication according to claim 1, wherein the node that has received the unreceived report transmits a packet corresponding to the unreceived report after a predetermined period has elapsed after receiving the unreceived report. Method.   The node that has received the unreceived report stops transmission of the packet when another node transmits the packet before the node transmits the packet corresponding to the unreceived report. The wireless communication method according to claim 2.   4. The wireless communication method according to claim 2, wherein the predetermined period is shorter as the reception strength of the unreceived report is stronger.   The wireless communication method according to claim 2 or 3, wherein the predetermined period is shorter as the transmission capability of the node that has received the unreceived report is higher.   The wireless communication method according to claim 2 or 3, wherein the predetermined period is determined based on position information of a node that has received the unreceived report. Packet receiving means for receiving packets destined for a plurality of destination nodes;
A reception report means for transmitting a reception report notifying that the packet has been received;
When a reception report is received from another node, if the own node is included in the destination of the packet corresponding to the reception report and the own node has not received the packet, the packet has not been received. An unreceived report means for transmitting an unreceived report to notify
A packet transmission means for transmitting a packet corresponding to the unreceived report when an unreceived report is received from another node;
A wireless communication apparatus comprising: Wireless communication device
Packet receiving means for receiving packets destined for a plurality of destination nodes;
A reception report means for transmitting a reception report notifying that the packet has been received;
When a reception report is received from another node, if the own node is included in the destination of the packet corresponding to the reception report and the own node has not received the packet, the packet has not been received. An unreceived report means for transmitting an unreceived report to notify
A packet transmission means for transmitting a packet corresponding to the unreceived report when an unreceived report is received from another node;
Wireless communication program to function as

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