JP6072627B2 - Wireless communication apparatus, data distribution method, and wireless communication system - Google Patents

Description

  The present invention relates to a wireless communication device, a data distribution method, and a wireless communication system that constitute a multi-hop wireless mesh network.

  With the expansion of needs for metering systems and remote management systems, wireless M2M (Machine to Machine) systems are expected to spread. Among wireless M2M systems, a system in which hundreds of radio devices (sometimes referred to as wireless communication devices and wireless terminals) are connected by a multi-hop wireless mesh network is also being studied. The cellular phone system is also a system in which a huge number of wireless devices exist, but since the user manages the terminal, the user performs maintenance such as software update and setting change at an arbitrary timing. However, in a wireless M2M system, a network administrator must maintain hundreds of radios. When it is necessary to update the radio software and parameters, if it is performed for each terminal like a mobile phone system, it takes time and effort for the number of devices. Therefore, a method of distributing to each wireless device via a wireless network can be considered. In particular, update of radio software and parameter update are efficient by distributing by multicast or broadcast because the data required for each radio is the same. However, in general multicast / broadcast communication, there is a problem that reliability is low because transmission is performed unilaterally from a transmitter to a receiver. As a method for solving this problem, a technique for improving reliability by applying retransmission control to multicast communication has been proposed (for example, Patent Document 1).

JP 2009-94863 A

  However, in the method proposed in Patent Document 1, it is necessary to mount a mechanism for executing retransmission control on the transmission side based on feedback information from the receiver. The more destination radios for multicast transmission, the more complex and the necessary resources. In addition, the proposed scheme is based on a star-type network, and is not considered for application to a multi-hop wireless mesh network studied in wireless M2M.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a wireless communication apparatus, a data distribution method, and a wireless communication system that realize highly reliable multicast / broadcast distribution in a multi-hop wireless mesh network. To do. Another object of the present invention is to obtain a wireless communication device, a data distribution method, and a wireless communication system that realize efficient data distribution.

  In order to solve the above-described problems and achieve the object, the present invention provides a wireless communication device constituting a multi-hop wireless mesh network, wherein a multicast frame transmitting means for transmitting a multicast frame, and the multicast frame transmitting means include Response frame collection means for collecting a response frame for the transmitted multicast frame from another wireless communication device, and the multicast frame transmission means includes: the response frame collection means, wherein the response frame collection means constitutes a multi-hop wireless mesh network. The same multicast frame is repeatedly transmitted until the response frame is received from all wireless communication apparatuses.

  According to the present invention, there is an effect that multicast distribution with high efficiency and high reliability can be realized.

FIG. 1 is a diagram illustrating a configuration example of a multi-hop wireless mesh network configured by a wireless communication device according to the present invention. FIG. 2 is a diagram illustrating a functional configuration example of a wireless communication device that is a parent node and a wireless communication device that is a child node. FIG. 3 is a flowchart showing an operation example when the parent node multicasts data. FIG. 4 is a diagram illustrating an operation in which a parent node generates a multicast frame. FIG. 5 is a flowchart showing an operation example when the child node receives data transmitted by multicast transmission. FIG. 6 is a diagram illustrating an operation of restoring the original transmission data from the multicast frame received by the child node.

  Hereinafter, embodiments of a wireless communication device, a data distribution method, and a wireless communication system according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  First, the multi-hop wireless mesh network assumed in each embodiment will be briefly described. FIG. 1 is a diagram illustrating a configuration example of a multi-hop wireless mesh network configured by a wireless communication device according to the present invention. A multi-hop wireless mesh network (hereinafter referred to as a wireless communication system) includes a wireless communication device 1 that operates as a parent node and a plurality of wireless communication devices 2 that operate as child nodes. The node transmits / receives various data to / from a part or all of the wireless communication devices 2 (child nodes). In FIG. 1, the first candidate path when the parent node and each child node communicate with each other is indicated by a solid line. The network may be a mesh network, that is, each node has second and third candidate routes, and when the communication quality of the first candidate route deteriorates, the network can be switched to the second and third candidate routes. . When the parent node communicates with a child node that is far away and cannot be directly communicated, the parent node communicates via a child node (relay node) capable of direct communication. In FIG. 1, all child nodes are within 2 hops from the parent node, but there may be child nodes with 3 or more hops.

  In each of the embodiments described below, a node located on the parent node side when viewed from a certain node, the node that becomes the transmission destination when transmitting to the parent node is the upper node, the opposite side of the parent node (the number of hops from the parent node is The node that is located in the direction of increasing) and that is the communication partner (transfer destination) is the lower node. In addition, a node existing in a position including a lower node (a direction in which the number of hops from the parent node increases) is referred to as a subordinate node. When viewed from a child node, the node that is directly on the communication path with the parent node (the other child node or parent node) is the upper node, and the child node that communicates with the parent node through itself is Corresponds to the subordinate node. Of the subordinate nodes, the node that directly communicates with corresponds to the lower node. For example, when the relay node (child node 1 hop from the parent node) shown in FIG. 1 is used as a reference, the parent node becomes an upper node and communicates with the parent node through itself. A child node becomes a lower node. When viewed from the parent node, the relay node is a lower node, and all child nodes are subordinate nodes.

  In each embodiment, data distributed by the parent node to each child node is referred to as distribution application data. Further, it is assumed that the parent node knows the identifier information of all the subordinate nodes, and each child node knows the identifier of each upper node and the identifier of the subordinate node. That is, the parent node holds identification information (identifiers) of all the child nodes that have already entered the multi-hop wireless mesh network, and the child node is an upper node (parent node, parent node) for communicating with the parent device. Identification information of other child nodes that are located on the communication path with each other, and identification information of all lower nodes (other child nodes that communicate with the parent node via itself) . The method by which the child node collects the identification information of the upper node and the lower node is not particularly defined. For example, it collects and holds when entering a multi-hop wireless mesh network.

Embodiment 1 FIG.
FIG. 2 is a diagram illustrating a functional configuration example of the wireless communication device 1 as a parent node and the wireless communication device 2 as a child node. In order to simplify the description, in FIG. 2, components related to the operation in which the wireless communication device 1 (parent node) transmits data to the wireless communication device 2 (child node) are described. Unrelated components are omitted.

  The wireless communication apparatus 1 includes an application data processing unit 11, a network control unit 12, a wireless access control unit 13, a wireless signal processing unit 14, and an antenna 15. The application data processing unit 11 includes a block division unit 111, a block error correction coding unit 112, a multicast frame generation unit 113, a multicast frame transmission control unit 114, and a delivery status management unit 115. The network control unit 12 includes a multicast transmission control unit 121. The wireless access control unit 13 includes a multicast transmission control unit 131.

  In the application data processing unit 11 of the wireless communication apparatus 1 that operates as a parent node that is a multicast distribution source of data, the block division unit 111 receives distribution application data that is the target data of multicast transmission, and receives a specified number of information blocks and blocks. The distribution application data is divided so as to have a unit size for error correction coding, and a plurality of information blocks are generated. The block error correction encoding unit 112 performs block error correction encoding processing on the information block generated by the block dividing unit 111. The multicast frame generation unit 113 receives the data block after the error correction encoding is performed by the block error correction encoding unit 112, and generates a multicast frame including the received data block. A multicast frame transmission control unit 114 as a multicast frame transmission unit transmits the multicast frame generated by the multicast frame generation unit 113 (outputs it to the network control unit 12). The multicast frame transmission control unit 114 repeats transmission of the same multicast frame until a certain condition is satisfied. The delivery status management unit 115 as a response frame collection unit sends a response frame (delivery confirmation signal) to the distribution application data restored from each multicast frame transmitted by the multicast frame transmission control unit 114 from the child node (wireless communication apparatus 2). Receive. At this time, the delivery status management unit 115 stores the child node that is the transmission source of the received delivery confirmation signal, and determines that the delivery confirmation signal has been received from all the child nodes that have joined the multi-hop wireless mesh network. This is notified to the multicast frame transmission control unit 114. The delivery confirmation signal is not transmitted for each multicast frame, but is transmitted for distribution application data transmitted using a plurality of multicast frames. That is, the delivery confirmation signal is transmitted when the distribution application data is correctly received (restored) by the child node.

  When the multicast transmission control unit 121 of the network control unit 12 receives the multicast frame from the multicast frame transmission control unit 114 of the application data processing unit 11, it performs a multicast transmission control process at the network level on the received multicast frame. Transmit (output to the wireless access control unit 13).

  When the multicast transmission control unit 131 of the wireless access control unit 13 receives the multicast frame from the multicast transmission control unit 121 of the network control unit 12, the multicast transmission control unit 131 performs multicast transmission control processing at the link level for the received multicast frame and transmits it. (Output to the wireless signal processing unit 14).

  When receiving the baseband signal (multicast frame) from the wireless access control unit 13, the wireless signal processing unit 14 converts it into a high frequency signal (wireless signal) and transmits it through the antenna 15. When a radio signal is received via the antenna 15, the radio signal is converted into a baseband signal and output to the radio access control unit 13.

  The wireless communication device 2 includes an application data processing unit 21, a network control unit 22, a wireless access control unit 23, a wireless signal processing unit 24, and an antenna 25. The application data processing unit 21 includes a block error correction decoding unit 211, a block error correction decoding availability determination unit 212, a multicast frame necessity determination unit 213, a frame type determination unit 214, and a delivery confirmation signal transmission unit 215. The network control unit 22 includes a multicast transmission control unit 221. The radio access control unit 23 includes a multicast transmission control unit 231.

  In the wireless communication device 2 that operates as a child node that receives multicast distribution of data from the parent node, the wireless signal processing unit 24 converts the data signal in the wireless band received by the antenna 25 into a baseband signal and converts the wireless access control unit 23. Output to. When the wireless signal processing unit 24 receives a response frame (delivery confirmation signal addressed to the parent node) for the received data signal from the wireless access control unit 23, the wireless signal processing unit 24 converts it into a wireless band signal and transmits it via the antenna 25. To do. Similarly, when the multicast frame to be transferred is received from the wireless access control unit 23, it is converted into a signal in the wireless band and transmitted through the antenna 25.

  The multicast transmission control unit 231 of the radio access control unit 23 receives the multicast frame from the radio signal processing unit 24, performs multicast transmission control processing at the link level on the received multicast frame, and outputs the multicast frame to the network control unit 22. . When the multicast transmission control unit 231 receives a multicast frame from the network control unit 22, the multicast transmission control unit 231 performs multicast transmission control processing at the link level on the received multicast frame and outputs the multicast frame to the radio signal processing unit 24.

  The multicast transmission control unit 221 of the network control unit 22 receives the multicast frame from the radio access control unit 23, performs a multicast transmission control process at the network level on the received multicast frame, and outputs the multicast frame to the application data processing unit 21. . The multicast transmission control unit 221 performs an operation as a frame transfer unit when there is a lower node. That is, in order to transfer the multicast frame received from the radio access control unit 23 to the lower node, the multicast transmission control process at the network level is performed on the multicast frame and output to the radio access control unit 23.

  In the application data processing unit 21, the frame type determination unit 214 determines the type of frame received from the network control unit 22. That is, it is determined whether the frame is a multicast frame. If it is a multicast frame, the frame is output to the multicast frame necessity determination unit 213, and if it is not a multicast frame, the frame is output to a non-multicast frame processing unit (not shown). For example, the non-multicast frame processing unit determines whether or not it is a unicast frame addressed to itself, and performs predetermined reception processing if addressed to itself. If it is not addressed to you, discard it. The multicast frame necessity determination unit 213 determines whether the multicast frame received from the frame type determination unit 214 is to be received. For example, when a received frame has been retransmitted (when a multicast frame normally received in the past has been retransmitted), it is determined that reception is unnecessary, and the received multicast frame is discarded. If it is determined that the multicast frame has not been received, it is output to the block error correction decoding availability determination unit 212. In the determination process, a past determination result (determination result for a multicast frame received in the past) in the block error correction decoding availability determination unit 212 is referred to. The block error correction decoding enable / disable determining unit 212 determines whether error correction is possible for the received multicast frame. If it is determined that the error correction is possible, the block error correction decoding enable / disable determining unit 212 outputs the multicast frame to the block error correction decoding unit 211 and sends a delivery confirmation signal. Is transmitted to the delivery confirmation signal transmission unit 215. The block error correction decoding unit 211 performs error correction decoding on the received multicast frame, and restores the transmitted data block. In response to an instruction from the block error correction decoding availability determination unit 212, the delivery confirmation signal transmission unit 215 as a response frame transmission unit uses the delivery confirmation signal (a signal indicating that the multicast frame has been normally received) as a unicast frame. To the wireless communication device 1 that is the parent node. Even if the block error correction decoding possibility determination unit 212 determines that error correction of the multicast frame is impossible, no retransmission request is made.

  Next, the characteristic operation of the communication device in the wireless communication system of the present embodiment, specifically, the wireless communication device 1 as a parent node multicasts distribution application data to the wireless communication device 2 as a child node. The transmission operation will be described separately for the transmission side and the reception side.

(Multicast transmission of data by parent node)
FIG. 3 is a flowchart showing an operation example when the parent node multicasts data.

  When the wireless communication device 1 that is a parent node receives distribution application data (step S11), the application data processing unit 11 first distributes distribution application data to be distributed to all child nodes in the system to the block dividing unit 111. Is divided into a prescribed size (step S12), and the block error correction coding unit 112 performs block error correction coding on each divided data block to generate an information block and a redundant block (step S13). Here, the block size, the block error correction code system and coding rate, the number of generated information blocks and the number of redundant blocks are not particularly limited.

  Next, the multicast frame generation unit 113 generates a multicast frame by giving a header of an identifier necessary for block error correction decoding on the reception side, for example, a data type, a frame identification number, and an application data processing unit level transmission source identifier. (Step S14). The multicast frame transmission control unit 114 receives a plurality of multicast frames generated in this way, and receives the received multicast frames to the network control unit 12 until delivery confirmation signals arrive from all the child nodes (wireless communication devices 2). The transfer is continued (steps S15 to S17). That is, the multicast frame transmission control unit 114 confirms that the delivery confirmation signal for the distribution application data has been received from all the child nodes in the system even after the transfer processing of all the generated multicast frames is completed. Until notified from 115 (until “Yes” is determined in step S16), the transmitted multicast frame is transmitted again. There is no restriction on the method of selecting a multicast frame to be transmitted again. When the delivery status management unit 115 is notified that the delivery confirmation signal for the distribution application data has been received from all the child nodes (step S16: Yes), the multicast frame transmission control unit 114 ends the transmission of the multicast frame ( Step S17).

  When the delivery status management unit 115 receives the delivery confirmation signal from the child node, the delivery status management unit 115 checks whether or not the delivery confirmation signal has been received from all the child nodes. The transmission control unit 114 is notified.

  The network control unit 12 adds a header storing a network level multicast identifier as a destination and a self-identifier as a transmission source to each multicast frame received from the application data processing unit 11, and performs radio access control as a NET frame. To the unit 13.

  The radio access control unit 13 gives a header storing a link level multicast identifier as a destination and its own identifier as a transmission source to the NET frame received from the network control unit 12, and the radio signal processing unit 14 as a MAC frame. Wireless transmission via.

  FIG. 4 is a diagram illustrating an operation (basic operation) in which a parent node generates a multicast frame. As shown in the figure, at the parent node, the distribution application data is divided into a plurality of data blocks (information blocks # 1, # 2,..., #N), and error correction coding processing is executed to obtain redundant data (redundant data). Blocks # 1, # 2,... Are generated. Further, an application level header is added to generate a multicast frame (multicast frames # 1, # 2,...), A network level header is added to the multicast frame, and a network level multicast frame (NET frames # 1, # 2) is generated. , ...) is generated. Finally, MAC frame # 1, # 2,... Are generated by adding a radio access control level header to the NET frame.

(Multicast data reception operation by child nodes)
FIG. 5 is a flowchart showing an operation example when the child node receives data transmitted by multicast transmission.

  The wireless communication device 2 that is a child node monitors reception of a frame and, when receiving the frame (step S21: Yes), determines whether it is a multicast frame (step S22). Specifically, first, the wireless access control unit 23 analyzes the header of the MAC frame that is the received frame, checks whether the destination identifier is multicast, and if it is multicast, deletes the header and goes to the network control unit 22. Forward. At this time, the transmission source identifier is confirmed, and whether or not the node is directly connected is also transferred to the network control unit 22. The network control unit 22 analyzes the header of the NET frame that is the transferred frame and checks whether the destination identifier is multicast. If the destination identifier is multicast, the header is deleted and transferred to the application data processing unit 21.

  In the application data processing unit 21, the frame type determination unit 214 determines whether or not the transferred frame is a multicast frame based on the header information (various information stored in the header). In the case of a multicast frame (step S22: Yes), the multicast frame necessity determination unit 213 further determines whether the data needs to be received (step S23). For example, it is determined whether there is an overlap with stored data. That is, it is determined that reception is unnecessary in the case of the same frame as that received in the past. If reception is not necessary (step S23: No), the transferred multicast frame is discarded (step S28). On the other hand, if reception is necessary (step S23: Yes), the data is stored (step S24). When the block is stored, the block error correction decoding enable / disable determination unit 212 confirms whether the distribution application data can be restored by block error correction decoding (step S25). If data restoration is impossible (step S25: No), the process returns to step S21 to wait for the next multicast frame. If data restoration is possible (step S25: Yes), the delivery confirmation signal transmission unit 215 transmits the delivery confirmation signal to the parent node (wireless communication apparatus 1) that is the data transmission source by unicast, and a block error. The correction decoding unit 211 performs a decoding process (steps S26 and S27). If it is determined in step S22 that the forwarded frame is not a multicast frame (step S22: No), normal data reception processing that is data transmitted by unicast is performed (step S22: No). Step S29).

  FIG. 6 is a diagram illustrating an operation (basic operation) for restoring original transmission data (distributed application data) from a multicast frame received by a child node. As shown in the figure, when the child node receives a plurality of multicast frames (MAC frames # 1, # 2,...) Generated by the parent node based on the distribution application data, first the header of the MAC frame is removed and the NET frame is removed. (NET frames # 1, # 2,...) Are extracted, and then the NET frame header is removed to extract multicast frames (multicast frames # 1, # 2,...). Further, the header of the multicast frame is removed to extract information blocks (redundant blocks # 1, # 2,...) And redundant blocks (redundant blocks # 1, # 2,...), And information block error correction is performed using the redundant blocks. Decrypt. Finally, the divided application data (information blocks # 1, # 2,..., #N) is combined to restore the distribution application data.

  The above is the data reception operation by the child node. In addition to this operation, the child node performs transfer processing of the received frame (multicast frame, unicast frame) as necessary.

  When the child node receives the unicast frame, the child node confirms the destination and transfers it according to the route information held in advance. For example, when a frame addressed to the parent node (such as a delivery confirmation signal) is received, the frame is transferred toward the parent node.

  When a multicast frame is received, frame transfer necessity determination and transfer are performed according to the following procedure. That is, when receiving a multicast frame from an upper node such as a parent node, the network control unit 22 of the child node checks whether or not a lower node exists, and if there is no lower node, the received multicast frame is Do not forward. On the other hand, when a lower node exists, multicast transfer is performed. Specifically, the multicast transmission control unit 221 of the network control unit 22 rewrites the transmission source address in the header of the frame received from the radio access control unit 23 with its own identifier, and outputs it to the radio access control unit 23 as a NET frame. To do. The transmission source address in the header may be transferred (output) to the wireless access control unit 23 without being rewritten. The radio access control unit 23 gives a header storing a link level multicast identifier as a destination and a self identifier as a transmission source to the NET frame received from the network control unit 22, and the radio signal processing unit 24 as a MAC frame. Wireless transmission via. Note that the network controller 22 performs the transfer only for the multicast frame received from the upper node in order to avoid congestion due to the backflow of the multicast frame to the upper node in the multi-hop network. Depending on the wireless environment, it may be possible to receive a multicast frame transmitted from a node that is not a higher-level node (a node that is more than two hops in the direction of the parent node or a subordinate node). If it is transferred and not duplicate data, it is retained, but the increase in traffic is suppressed by not performing the transfer process to the lower node. Alternatively, the multicast frame received from the node in the parent node direction before the upper node may be transferred, and the same multicast frame received from the upper node after that may not be transferred.

  In the case of a mesh network, there are a plurality of upper nodes, and there is a possibility that the number of multicast frames to be transmitted increases. For this reason, when multicast relaying is performed, upper nodes to be transferred may be narrowed down.

  Here, the method for determining whether or not the network control unit 22 is a multicast frame transmitted from an upper node is not particularly defined. It may be realized in cooperation with the wireless access control unit 23, or when the child node transfers, the network control unit 22 rewrites the transmission source address with its own identifier, and determines from the transmission source address of the NET frame. Also good. At this time, even if the transmission source address is an upper node, the transmission confirmation signal transmission destination is set to be the parent node. An index such as the number of hops may be stored in the header, and the determination may be made from the number of hops (number of transfers).

  As described above, in the wireless communication system according to the present embodiment, when a parent node serving as a data distribution source transmits distribution data by multicast, all the child nodes in the distribution destination system normally receive the data. The multicast transmission of the same data is repeatedly performed until it is detected, that is, until the delivery confirmation signal is received from all the child nodes. On the other hand, the child node transmits a delivery confirmation to the parent node when the distribution application data can be normally restored from the multicast-transmitted data (multicast frame). Thereby, efficient and reliable multicast transmission can be realized.

  In addition, since the child node receives the multicast data from the upper node and decides to multicast the data when the lower node exists, the child node avoids transferring the multicast frame more than necessary to avoid traffic. The increase can be suppressed. By suppressing the increase in traffic, the rate of frame collision can be suppressed, and the reliability can be improved.

  In addition, application of block error correction code improves resistance to errors on the communication path, and can realize efficient data transmission. In addition, the application of multicast improves the efficiency of transmission by realizing a plurality of communications at once. Furthermore, since the frame is transferred to the application data processing unit regardless of the transmission source, a path diversity effect can be obtained by receiving information from a node that is not a normal communication path. With these comprehensive effects, the same data can be efficiently and reliably distributed from the parent node to each child node in the multi-hop wireless mesh network.

Embodiment 2. FIG.
In the first embodiment, it is not considered that the multicast frame transmitted by the parent node collides with the multicast frame relayed (transferred) by the child node. Therefore, in the present embodiment, the transmission frequency of the parent node is controlled in the wireless communication system described in the first embodiment. Specifically, the statistical value of the number of child nodes to be relayed and the number of transmissions of multicast frames (≈ number of error occurrences) transmitted until receiving the acknowledgment signal from all the child nodes at the time of the previous multicast distribution execution is used as an index. Controls the transmission interval of multicast frames. For example, when the number of relayed child nodes is large, and when the number of multicast frames transmitted before receiving the acknowledgment signal from all the child nodes is large, the parent node transmits by increasing the multicast frame transmission cycle. Reduce the frequency. The transmission period may be determined in consideration of both the number of child nodes to be relayed and the number of transmissions of multicast frames transmitted from the reception of all the child nodes. The configuration of the parent node is the same as that of the first embodiment (see FIG. 2).

  The multicast frame transmission control unit 114 of the parent node having the above-described function suppresses errors due to intra-system interference occurring on the wireless network compared to the first embodiment, and the multicast frame transmitted by the parent node. The effect of reducing the number is obtained.

Embodiment 3 FIG.
In Embodiments 1 and 2, since the parent node continues to transmit the multicast frame until it receives an acknowledgment signal from all the child nodes, the parent node and the child nodes that are relay nodes have more transmission opportunities. . Therefore, in the present embodiment, in the wireless communication system described in the first or second embodiment, the function (see FIG. 2) of the application data processing unit 11 provided in the parent node and the delivery confirmation to the upper node. A child node that has a signal transmission function and relays the distribution application data that has been restored performs multicast frame transmission on behalf of the parent node.

  That is, in the wireless communication system according to the present embodiment, when the restoration of the distribution application data is completed by the multicast frame received from the upper node, the child node in which the lower node exists transmits an acknowledgment signal to the parent node and the upper node. Transmit and perform multicast frame generation and transmission processing on behalf of the parent node and upper node. When the parent node and the child node that has taken over the processing receive the delivery confirmation signal from all the lower nodes, the multicast transmission frame is repeatedly transmitted. In this way, the lower node takes over the delivery of the multicast frame.

  As described above, the child node according to the present embodiment can reduce the transmission load of a node close to the parent node by taking over the multicast distribution process by the parent node and further taking over the process to the lower node. As a result, the number of multicast frame transmissions can be suppressed, and the number of multicast frames transmitted by the parent node or relaying child node can be reduced as compared with the first and second embodiments.

Embodiment 4 FIG.
In the third embodiment, the transmission of the delivery confirmation signal to the upper node is used as a trigger, and the child node that has transmitted the delivery confirmation signal starts the multicast frame generation and transmission process. For this reason, even if the upper node does not stop the transmission of the multicast frame, the lower child node starts the proxy transmission, and wasteful data transmission occurs.

  Therefore, the child node of the present embodiment completes reception of the multicast frame, transmits a delivery confirmation signal to the upper node, and then uses a timer to confirm that the multicast frame has not been received from the upper node for a certain period of time. In this case, proxy processing (processing for generating and sending a multicast frame from distribution application data) is started. Alternatively, after the upper node receives the delivery confirmation signal from all the lower nodes, the lower node may be instructed to start the substitution (the child node starts the substitution process after receiving the instruction). In addition, the child node simply transmits a delivery confirmation signal and starts a proxy process, and then performs a transfer process of the multicast frame (the same multicast frame transmitted by the proxy process) transferred from the upper node. You may decide not to do it. The other parts are the same as in the third embodiment.

  Note that the timer value is a value determined based on the scale of the system (number of child nodes), for example. Further, it may be a value determined based on the network configuration, specifically, the number of lower nodes that directly receive the multicast frame from the upper node.

  According to the present embodiment, the amount of data communicated in the entire system can be reduced as compared with the third embodiment.

Embodiment 5. FIG.
In the fourth embodiment, it is difficult to set an optimum timer value after transmission of a delivery confirmation signal to an upper node until the start of proxy processing, because it differs depending on the system configuration and the surrounding wireless environment (depending on the system configuration and the wireless environment). It was necessary to change the timer value setting). Further, in the case of a network configuration having a plurality of upper nodes, it may be difficult to control the lower nodes. Therefore, the parent node and the child node of the present embodiment collect and hold the network configuration information in advance, and the parent node and the child node having the lower nodes perform proxy operations while confirming the delivery status of the multicast frame. A lower-level node that executes processing is specified. That is, the child node starts the proxy process when receiving an instruction from the upper node after transmitting the delivery confirmation signal. The parent node or the upper node instructs the start of the proxy process to a part or all of the subordinate nodes at a timing when a certain condition is satisfied. For example, when a delivery confirmation signal is received from all the lower nodes, a lower node to perform the processing is selected, and the selected lower node is instructed to start the proxy processing. The selection of the lower node that performs the processing is performed based on, for example, the presence / absence of a subordinate node. That is, a subordinate node having subordinate nodes is selected, and proxy processing is executed. The other parts are the same as in the fourth embodiment.

  According to the present embodiment, complicated settings and control in accordance with system characteristics and the like are not required.

Embodiment 6 FIG.
In the first to fifth embodiments, even if the number of child nodes that have not received the distribution application data decreases, the upper node (the child node having the parent node and the lower node) continues to transmit the multicast frame. Will increase. In addition, even if reception of the distribution application data is completed on the receiving side, if a multicast frame is received, reception processing is performed until the application data processing unit 11 (see FIG. 2) recognizes unnecessary data (data that does not need to be received). Will run out of power.

  Therefore, in the present embodiment, in the wireless communication systems described in the first to fifth embodiments, the number of child nodes that have not received distribution application data to the number or configuration that does not have the effect of improving transmission efficiency by multicast transmission is reduced. If this is detected (when the number of child nodes to which the delivery confirmation signal has not been transmitted becomes a certain number or less), the transmission source node of the distribution application data is switched to unicast transmission.

  By providing the above functions in the parent node and the child node, it becomes possible to suppress useless data transmission as compared with the first to fifth embodiments, and it is also possible to reduce the power consumption of each node. .

  The conditions for switching to unicast may be the same for all parent nodes and relay nodes (child nodes having lower nodes), or individual conditions may be set for each node. The condition may be set so that only a part of the parent node and the relay node is switched to unicast. When a relay node transmits a data frame in place of a higher-order node, the relay node may perform unicast transmission from the beginning if there are few subordinate nodes.

  In each embodiment, the case where the distribution application data is multicast-transmitted has been described. However, the present invention can also be applied to the case where the broadcast application transmission is performed.

  As described above, the wireless communication apparatus according to the present invention is useful for a multi-hop wireless mesh network, and in particular, a multi-hop wireless mesh in which a specific node needs to distribute the same data to all other nodes. Suitable for network.

  1, 2 Wireless communication device, 11, 21 Application data processing unit, 12, 22 Network control unit, 13, 23 Wireless access control unit, 14, 24 Wireless signal processing unit, 15, 25 Antenna, 111 block division unit, 112 blocks Error correction encoding unit, 113 multicast frame generation unit, 114 multicast frame transmission control unit, 115 delivery status management unit, 121, 131, 221, 231 multicast transmission control unit, 211 block error correction decoding unit, 212 block error correction decoding availability Determination unit, 213 Multicast frame necessity determination unit, 214 Frame type determination unit, 215 Delivery confirmation signal transmission unit.

Claims (8)

A wireless communication device constituting a multi-hop wireless mesh network,
A multicast frame transmitting means for transmitting the multicast frame;
Response frame collecting means for collecting a response frame for the multicast frame transmitted by the multicast frame transmitting means from another wireless communication device;
With
The multicast frame transmitting means repeatedly transmits the same multicast frame in past data distribution until the response frame collecting means receives the response frame from all other wireless communication devices constituting the multi-hop wireless mesh network. A wireless communication apparatus that repeatedly transmits the same multicast frame at a period determined based on the number of times the transmission is performed. A wireless communication device constituting a multi-hop wireless mesh network,
Frame transmission means for transmitting a multicast frame;
Response frame collection means for collecting a response frame for the multicast frame transmitted by the frame transmission means from another wireless communication device;
With
It said frame transmitting means, from said response frame collection means multi-hop wireless mesh configuration to have a certain number or more other wireless communication devices a network until it receives the response frame, repeatedly transmits the same multicast frame, the same multicast After completing the operation to transmit the frame repeatedly, the unicast frame that stores the same data as that stored in the multicast frame that has been repeatedly transmitted until then is sent to the other frames that have not yet received the response frame. A wireless communication device that transmits to a wireless communication device. A wireless communication device that constitutes a multi-hop wireless mesh network together with a multicast frame distribution source device that repeats transmission of the same multicast frame until a response frame to the multicast frame is received from a certain number of wireless communication devices in the network,
Response frame transmitting means for transmitting a response frame indicating normal reception when the multicast frame generated by the multicast frame distribution source device is normally received;
When there is a subordinate node that is another wireless communication device that normally receives the multicast frame generated by the multicast frame distribution source device and communicates with the multicast frame distribution source device via itself, the multicast frame Frame transfer means for transferring
Equipped with a,
The frame transfer means repeatedly transmits the same multicast frame as the received multicast frame until a response frame to the multicast frame is received from a certain number of subordinate nodes, and ends the operation of repeatedly transmitting the same multicast frame. unicast frame storing the same data as that stored in the repetition multicast frames have been transmitted to, characterized that you sent to subordinate nodes reception has not been completed in response frame at that time Wireless communication device. A wireless communication device that constitutes a multi-hop wireless mesh network together with a multicast frame distribution source device that repeats transmission of the same multicast frame until a response frame to the multicast frame is received from a certain number of wireless communication devices in the network,
Response frame transmitting means for transmitting a response frame indicating normal reception when the multicast frame generated by the multicast frame distribution source device is normally received;
When there is a subordinate node that is another wireless communication device that normally receives the multicast frame generated by the multicast frame distribution source device and communicates with the multicast frame distribution source device via itself, the multicast frame Frame transfer means for transferring
With
The frame transfer means is determined based on the number of wireless communication devices constituting the multi-hop wireless mesh network or the network configuration of the multi-hop wireless mesh network after transmission of the response frame by the response frame transmitting means is completed. after time has elapsed, until it receives a response frame for the multicast frames from all subordinate nodes one hop lower, the successfully repeated the same multicast frame as received multicast frame transmission radio communications device you characterized in that . The frame transfer means is determined based on the number of wireless communication devices constituting the multi-hop wireless mesh network or the network configuration of the multi-hop wireless mesh network after transmission of the response frame by the response frame transmitting means is completed. 4. The wireless communication apparatus according to claim 3 , wherein transmission processing is started after a lapse of time. The frame forwarding means repeats transmission of the same multicast frame as the received multicast frame when receiving a multicast frame forwarding instruction corresponding to the response frame after transmission of the response frame by the response frame sending means is completed. The wireless communication apparatus according to claim 3 , wherein the wireless communication apparatus starts. A data distribution method executed by a wireless communication device in a multi-hop wireless mesh network,
A multicast transmission step for multicast transmission of distribution data;
A delivery confirmation collection step for collecting delivery confirmation for the multicast transmitted data from a wireless communication device in a multi-hop wireless mesh network;
Including
In the acknowledgment collection step, from all the other wireless communication apparatus of the multi-hop wireless mesh network to collect the acknowledgment was determined based on the number of times of repeatedly transmitting the same multicast frames on historical data distribution period in the data distribution method which is characterized in that repeatedly executes the multicast transmission step. And the parent node is a radio communication apparatus according to claim 1 or 2,
A child node which is the wireless communication device according to any one of claims 3 to 6 ,
A wireless communication system comprising:

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