JP6424668B2 - Route information collection program, route information collection method, and node device - Google Patents

Description

  The present specification relates to a route information collection program, a route information collection method, and a node device.

  The ad hoc communication technology refers to a communication technology in which devices directly communicate with each other without passing through an access point. In recent years, each communication device to which ad hoc communication technology is applied recognizes surrounding communication devices, and wireless ad hoc network technology attracts attention.

  As an example of the routing protocol (ad hoc protocol) of the ad hoc network, there are reactive AODV (Ad Hoc On Demand Distance Vector Algorithm) and proactive OLSR (Optimized Link State Routing). Furthermore, as an example of an ad hoc protocol, prior to a communication request, each node constructs a route (route) for performing data communication autonomously in advance, and further, it proactively learns the optimal route at any time and changes the route. There is a typed routing protocol.

The following techniques are examples of techniques related to an ad hoc network.
As a first technique, there is a packet routing method in a system that transmits a packet to a destination wireless terminal device via a plurality of wireless terminal devices (for example, Patent Document 1). According to the first technique, a wireless terminal apparatus relaying a packet monitors for route disconnection. The wireless terminal device that has detected a route disconnection transmits a route search packet to the wireless terminal device of the packet destination, and notifies the source wireless terminal device of the route disconnection. The relaying wireless terminal reconstructs the packet transfer route according to the route search packet. The transmission source wireless terminal apparatus performs route reconfiguration when it receives information on route disconnection.

  As a second technology, there is a packet routing method in a system for transmitting a packet to a destination wireless terminal via a plurality of wireless terminal devices (for example, Patent Document 2). In the second technology, the wireless terminal apparatus to be relayed detects that the communication with the wireless terminal apparatus transmitting the packet directly using the wireless signal is disconnected. The wireless terminal apparatus that has detected that the communication has been disconnected determines whether the apparatus is located on the side of the wireless terminal apparatus of the packet destination or the wireless terminal apparatus of the transmission source. The wireless terminal apparatus determined to be on the wireless terminal apparatus side of the transmission source transmits, by broadcast, a request signal for path restoration to the wireless terminal apparatus of the packet destination. When the wireless terminal apparatus at the packet destination sends a request signal for path recovery, it broadcasts a request for path reconfiguration to the wireless terminal apparatus at the packet transmission source.

  As a third technology, there is a technology in which an appropriate route is selected and data is transmitted as a result of autonomous distributed processing by each node device as the entire network (for example, Patent Document 3). In the third technique, when a frame that has been transmitted by a node device is received by the node device itself via the network, an adjacent node device other than the previously selected adjacent node device is tried as a transmission destination. Then, if there is no adjacent node device capable of transmission, the received frame is transmitted to the third adjacent node device by the backtracking means, so that the third adjacent node device may try another new route. it can.

  As a fourth technology, there is a technology for monitoring the state of communication paths in a network (for example, Patent Document 4). In the fourth technique, a first node device in a network including a plurality of node devices is transmitted from a node device to which a frame addressed to an end node, which is a node device at an end point of a path to be checked for communication quality, Select the destination of the first survey frame to be used for route survey. When the first node device fails to transmit the first survey frame to the second node device selected as the transmission destination of the first survey frame, the first node device and the second node device Generate a second survey frame that records that the communication between them failed. The first node device selects a third node device to which the second examination frame is to be transmitted, from the node devices to which the frame addressed to the end node is to be transferred. The first node device transmits the second examination frame to the third node device, whereby communication between the first node device and the second node device is performed via the third node device. Notify the end node that it failed.

JP, 2005-269623, A JP 2005-236687 A International Publication No. 2011/0013165 JP, 2014-183348, A

  The nodes constructing an ad hoc network communicate with each other to transmit frames (path collection frames) for collecting path information while repeating relaying from the transmission start node (origin node) to the target node Be done. In the route collection frame, route information is accumulated and added each time the relay node passes. When the route collection frame finally returns to the source node, the source node can acquire route information between the source node and the target node.

  However, if the route collection frame is lost halfway due to the occurrence of a communication failure and does not return to the originating node, the originating node can not acquire route information between the originating node and the target node at all. Therefore, it is not possible to follow up or identify the route in which the communication failure has occurred.

  According to one aspect of the present invention, a technique is provided to assist in tracking a path when a communication failure occurs.

In one aspect of the present invention, node devices included in a plurality of node devices constructing a communication network from a data transmission source to a data transmission destination are caused to execute the following processing. Node device sent from the data source to the first, the communication information has information of the communication path A communication information to the data destination and the final destination from the data source to the node device, the communication Communication information which is received from the preceding node device in the route and added with identification information of the subsequent node device in the communication route up to the data transmission destination of the communication information to the information of the communication route contained in the received communication information The return is communication information having the information of the same communication route as that of the communication information transmitted to the subsequent node device and transmitted to the subsequent node device and having the data transmission source as the final destination The above communication information is transmitted to the preceding node device .

  In one aspect of the present invention, tracking of a path in case of communication failure can be supported.

An example of trace route operation in a mesh-like ad hoc network in the 4th technology is shown. An example of trace route operation when there are many hops in the 4th technology is shown. An example of the node apparatus in this embodiment is shown. An example of trace route operation | movement in this embodiment is shown. FIG. 4 shows an operation sequence corresponding to FIG. An example of trace route operation in case the number of hops in this embodiment is large is shown. The example of the format of an ad hoc control data frame in this embodiment is shown. It is an example of hardware constitutions of the node in this embodiment. It is an example of a functional block diagram of a node regarding frame transmission and reception in this embodiment. An example of the link table in this embodiment is shown. An example of the routing table in this embodiment is shown. An example of the TND routing table in this embodiment is shown. 6 illustrates an example of updating a TND routing table in the present embodiment. The transmission processing flow of the route collection frame (for forward trip) of the origin node in this embodiment is shown. The reception processing flow of the return frame of the origin node in this embodiment is shown. The reception processing flow of the route collection frame (for return trip) of the origin node in this embodiment is shown. The processing flow when the reception waiting time of the route collection frame (for return route) of the start point node in this embodiment times out is shown. FIG. 10 shows a flow of processing for receiving a route collection frame (for forward route) of the relay node in the present embodiment. FIG. The reception processing flow of the return frame of the relay node in this embodiment is shown. 5 shows a reception processing flow of backtrack frames of the relay node in the present embodiment.

  For example, in the fourth technology described above, there is a trace route function capable of confirming the route through which data is communicated in the ad hoc network autonomously constructed by each node. In this trace route function, each node to be relayed adds its own path information to the path collection frame transmitted by the transmission start node and transfers it. This makes it possible to identify the information of the node that has passed between the transmission origin node and the final destination destination node 迄. Further, even when path switching occurs due to transmission failure, it is possible to obtain path information including information on the path switching.

  The trace route function can obtain route information when the route collection frame returns to the transmission start node.

  However, in a wireless communication environment in which the situation changes momentarily due to various external factors, communication failure may occur temporarily in a shorter period than the control message (HELLO) periodically transmitted and received between nodes. There is sex. In this case, since the autonomous route information change is not performed, it is conceivable that the route collection frame may not return to the transmission start node if the route collection frame disappears along the route.

  In that case, the transmission start node can not acquire path information up to the middle. In such a case, it becomes necessary for the maintenance person to investigate the failure path by using ping or the like, and it takes time to maintain the communication environment. In addition, the delay in the maintenance of the communication environment may cause a drop in the arrival rate of business data such as meter reading.

  FIG. 1 shows an example of trace route operation in a mesh ad hoc network in the fourth technology. Node devices (hereinafter referred to as "nodes") A to E are communication terminals equipped with a wireless ad hoc communication technology.

  First, the trace route operation in the case where the route information can be acquired will be described using FIG. 1 (A). In FIG. 1A, a case where the transmission start node A transmits a route collection frame to the target node E will be described. Here, path collection frames are transmitted and received between nodes. Every time a relay node passes, route information on whether or not it is possible to transmit from the relay node to another adjacent relay node is added to the route collection frame.

  (A1) The node A adds, to the route collection frame, route information in which “success” is set in “transmission result addressed to node B”, and transmits the route collection frame to the node B. As a result, it is assumed here that transmission to node B has failed.

  (A2) The node A detects a transmission failure of the route collection frame to the node B, and changes the “transmission result to node B” of the route collection frame to “failure”. After that, the node A adds the path information in which “success” is set to “transmission result for node C” to the path collection frame, and transmits the path collection frame to the node C. It is assumed that the transmission of the route collection frame from node A to node C has been successfully performed.

  (A3) The node C adds the path information in which “success” is set to “transmission result for node D” to the received path collection frame, and transmits the path collection frame to the node D. It is assumed that the transmission of the route collection frame from node C to node D has been successfully performed.

  (A4) The node D adds, to the received route collection frame, the route information in which “success” is set in “transmission result for node E”, and transmits the route collection frame to the node E. As a result, it is assumed here that transmission to node E has failed.

  (A5) The node D detects a transmission failure of the route collection frame to the node E, and changes the “transmission result to node E” of the route collection frame to “failure”. After that, the node D adds the route information in which “success” is set to “transmission result addressed to node C” to the route collection frame, and transmits the route collection frame to the node C (backtrack). It is assumed that the transmission of the route collection frame from node D to node C has been successfully performed.

  (A6) The node C adds, to the received frame, the route information in which “success” is set in “transmission result for node A”, and transmits the route collection frame to the node A. It is assumed that the transmission of the route collection frame from node C to node A has been successfully performed.

  Next, a trace route operation in the case where the route information can not be acquired will be described using FIG. 1 (B).

  (B1) The node A adds, to the route collection frame, route information in which “success” is set in “transmission result addressed to node B”, and transmits the route collection frame to the node B. As a result, it is assumed here that transmission to node B has failed.

  (B2) The node A detects a transmission failure of the route collection frame to the node B, and changes the “transmission result to node B” of the route collection frame to “failure”. After that, the node A adds the path information in which “success” is set to “transmission result for node C” to the path collection frame, and transmits the path collection frame to the node C. It is assumed that the transmission of the route collection frame from node A to node C has been successfully performed.

  (B3) The node C adds, to the received route collection frame, the route information in which “success” is set in “transmission result for node D”, and transmits the route collection frame to the node D. It is assumed that the transmission of the route collection frame from node C to node D has been successfully performed.

  (B4) The node D adds, to the received route collection frame, the route information in which “success” is set in “transmission result for node E”, and transmits the route collection frame to the node E. As a result, it is assumed here that transmission to node E has failed.

  (B5) The node D detects a transmission failure of the route collection frame to the node E, and changes the “transmission result to node E” of the route collection frame to “failure”. In this case, since the route to the target node E is dead before reaching the target node E, the traveling direction of the route collection frame is changed from the target node to the transmission start node (backtrack) . Therefore, node D adds the route information in which “success” is set to “transmission result addressed to node C” to the route collection frame, and transmits the route collection frame to node C. As a result, it is assumed here that transmission to node C has failed. Then, the node A loses the route acquisition frame (backtrack frame) without being able to obtain the route information added in the above (B3) and (B4).

  (B6) The node A detects a timeout of reception waiting time of the backtrack route collection frame. In this case, the node A can not obtain any route information, resulting in failure in route collection.

  FIG. 2 shows an example of trace route operation when the number of hops is large in the fourth technology. In FIG. 2, although it is desired to acquire the route from node A to node Z, the route collection frame can only reach node X and the route collection frame (backtrack frame) disappears among nodes F to E. An example of

  In FIG. 2, it is assumed that the node A wants to confirm the route from the node A to the node Z, but the route collection frame only reaches the node X. That is, although the node X transmits a route collection frame to the node Y, it is assumed that the transmission fails (B11).

  If one communication path is disconnected, node X attempts to transmit to node Y on the other communication path (B12). It is assumed that the route collection frame did not reach node Y and did not reach to another node (Y ′, Y ′ ′) (not shown). As a result, receiving an acknowledgment (ACK) frame for transmission of the route collection frame Since it can not do so, upon detecting a timeout due to an excess of ACK reception waiting time, the node X transmits a route collection frame to the transmission origin node (backtrack) (B13).

  Here, time may have passed since the previous communication, and communication may become impossible due to a change in radio wave conditions or the like. It is assumed that the path collection frame (backtrack frame) is lost due to a communication failure between the nodes E and F (B14). If the backtrack frame does not return, the node E does not know the communication path at all, so it is difficult to identify where the communication failure has occurred.

  According to FIG. 2, as the hop number increases, the elapsed time T1 from the previous communication (frame transmission from node A to node Z) to the return of the backtrack frame increases. As a result, there is a high possibility that a change in radio wave conditions will occur, and the possibility of communication failure will also increase. The same is true for any of the nodes B to Y, so the higher the number of hops, the higher the possibility that the backtrack frame will be lost.

  As described above, when a communication failure occurs such that a frame is lost along the route, the failure area can not be narrowed down at all, and the maintenance person needs to perform the following investigation. Maintenance personnel go close to each node, refer to the information in the link table and routing table, and investigate the route from the source to the final destination (if the number of hops is large, there may be dozens of target nodes). ).

  In addition, based on the surveyed route information, survey paths such as trace routes and pings are used multiple times for each node to narrow down the path that is the cause. In addition, these surveys can only be performed by a maintainer who understands the operation details of ad hoc routing, and can not be performed by any maintainer, so the survey efficiency tends to deteriorate.

  Therefore, in the present embodiment, each relay node transmits route data to the next hop node, and transmits route data at that time to the transmission origin node of route collection. The transmission origin node can know which node the route collection frame has reached, and even if the frame is lost on the way, it is possible to obtain route information up to before the loss.

  As a result, each node on the route transmits the same frame (loopback frame) as the route collection frame to the node at the transmission origin of the route collection, so that the node at the transmission origin collects the route to each node on the route. It becomes possible to grasp the arrival situation of the frame.

  In addition, by utilizing the management information for managing the source node between the adjacent nodes, the return frame is transferred to the node of the transmission start point by following the same route as the route collection frame, so the latest usage history It is possible to use a certain route.

  Hereinafter, the present embodiment will be described in detail with reference to the drawings. First, the terms in the present specification will be described.

  "Frame" refers to a data unit based on a protocol used in an ad hoc network. For example, “frame” includes, but is not limited to, “hello message frame” and “data frame”.

  The “Hello message frame (HELLO message frame)” is a type of control frame for communicating control information, and node devices transmit to another node device for confirmation of their existence / status. Refers to a special frame. The HELLO message frame may be simply referred to as a HELLO message.

  "Data frame" refers to data that the network is trying to transmit (from the start node to the goal node).

  "Global Destination (GD)" refers to a node ID that is the final destination in an ad hoc network. In the present specification, GD may be referred to as "global destination address".

  "Global Source (GS)" refers to the node ID that is the first source in an ad hoc network. In the present specification, GS may be referred to as "global source address".

  "Local Destination (LD)" means the destination node ID of a frame between adjacent nodes that relays a frame transmitted from a node of "global source address (GS)" to a node of "global destination address (GD)" Point to In the present specification, LD may be referred to as "local destination address".

  "Local Source (LS)" means the source node of a frame between adjacent nodes that relays a frame transmitted from a node of "global source address (GS)" to a node of "global destination address (GD)" It refers to the ID. In the present specification, LS may also be referred to as "local source address".

  FIG. 3 shows an example of a node device in the present embodiment. The node device 1 is a node device included in a plurality of node devices constructing a communication network from a data transmission source to a data transmission destination. The node device 1 includes a receiver 2 and a transmitter 3. An example of the node device 1 is a node 11 (FIG. 9). An example of the communication network is an ad hoc network.

  The receiving unit 2 receives communication information transmitted from another node device. An example of the receiver 2 is a receiver 26 (FIG. 9).

  The transmitting unit 3 transmits communication information obtained by adding identification information of a subsequent node device in a communication communication path to the received communication information to a preceding node device and a subsequent node device in the communication path. More specifically, the transmitting unit 3 transmits, to the node apparatus of the former stage, return information which is communication information transmitted to the node apparatus of the former stage, with the transmission source as the starting point as the final destination. The routing unit 23 and the transmission unit 27 can be given as an example of the transmission unit 3. An example of the identification information of the subsequent node device is the node ID of the subsequent node.

  By configuring in this way, the node that is the data transmission source (transmission start point) can acquire route information on the way to the node that reached by relay regardless of the reception of the route collection frame, so a communication failure occurs. Makes it easy to follow up the route.

  The node device 1 further includes a storage unit 4. When receiving the communication information from the node apparatus of the previous stage, the node apparatus 1 holds the identification information of the node apparatus of the previous stage in the storage unit 4. The RAM 14 or the non-volatile memory 15 (FIG. 8, FIG. 9) storing the transmission source (LS) node information 34 may be mentioned as an example of the storage unit 4 holding the identification information of the preceding node device. At this time, when the transmitting unit 3 receives the return information from the subsequent node device, the transmitting unit 3 transmits the return information to the preceding node device using the stored identification information.

  By configuring in this way, the turnaround information is transferred to the origin node by following the same route as the forward route, so it is possible to use a route that has been used most recently.

  The node device 1 further includes a specifying unit. The identifying unit 5 identifies the communication status between the node devices of the communication path based on the reception confirmation information for the transmitted communication information received from the node device at the subsequent stage. The routing 23 is mentioned as an example of a specific part.

  By configuring in this way, it is possible to monitor the state of the communication path in the network.

  Also, the receiving unit 2 receives the communication information from the node apparatus at the subsequent stage. Then, the transmitting unit 3 transmits, to the preceding node device, communication information in which the identification information of the preceding node device is added to the communication information received from the succeeding node device.

  With such a configuration, each node device can relay the route collection frame (return route).

The details of the present embodiment will be described below.
FIG. 4 shows an example of the trace route operation in the present embodiment. FIG. 5 shows an operation sequence corresponding to FIG. In FIG. 4 and FIG. 5, it is assumed that the node A starts the route collection between the nodes A and E (outbound path) addressed to the node E. Here, path collection frames are transmitted and received between nodes. Every time a relay node passes, route information on whether or not it is possible to transmit from the relay node to another adjacent relay node is added to the route collection frame.

  (S1) The node A adds, to the route collection frame, the route information in which “success” is set in “transmission result addressed to node B”, and transmits the route collection frame to the node B. As a result, it is assumed here that transmission to node B has failed.

  (S2) The node A detects a transmission failure of the route collection frame to the node B, and changes the “transmission result to node B” of the route collection frame to “failure”. After that, the node A adds the path information in which “success” is set to “transmission result for node C” to the path collection frame, and transmits the path collection frame to the node C. It is assumed that the transmission of the route collection frame from node A to node C has been successfully performed.

  (S3) When receiving the route collection frame from the node B, the node C adds, to the received route collection frame, route information in which “success” is set in “transmission result for node D”. The node C transmits a route collection frame to which the route information is added to the node D (assuming that the transmission of the route collection frame from the node C to the node D is normally performed).

  At this time, the node C transmits a route collection frame (loopback frame) to which the route information is added to the node A which is the transmission source (the transmission of the route collection frame from the node C to the node A is normally performed). Let's say). Note that no route information is given to the return frame at the relay node passing through to the final destination node. The node A understands that the node C has transmitted to the node D by analyzing the received return frame.

  (S4) When receiving the route collection frame from the node C, the node D adds, to the received route collection frame, route information in which “success” is set in “transmission result addressed to node E”. The node D transmits a route collection frame to which the route information is added to the node E (as a result, here, it is assumed that the transmission to the node E has failed).

  At this time, the node D transmits a route collection frame (loopback frame) to which the route information is added to the source A addressed to the node A via the node C (the transmission of the route collection frame from the node D to the node A is normal) To be done). Note that no route information is given to the return frame at the relay node passing through to the final destination node.

  The node A analyzes that the received return frame indicates that the node D has transmitted to the node E. Also, even if the node A can not receive the route collection frame for some reason (communication failure etc.) in the above (S3), the node A arrives because the arrival information can be overwritten by receiving the route collection frame in the above (S4) Can be confirmed.

  (S5) The node D detects a transmission failure of the route collection frame to the node E, and changes the “transmission result to node E” of the route collection frame to “failure”. After that, the node D adds the route information in which “success” is set to “transmission result addressed to node C” to the route collection frame, and transmits the route collection frame to the node C (backtrack). As a result, it is assumed here that transmission to node C has failed. In addition, when transmitting a backtrack, transmission of a return frame is not performed.

  Then, in a state where the node A obtains the route information in the above (S3) and (S4), the route collection frame disappears. Here, transmission to the node C (back track) in the (S5) is transmitted to the node C or the node E in the above (S4), and then a failure in transmission to the node E in the above (S4) Do after the time has passed. Therefore, there is a high possibility that the communication environment changes before and after the transmission to node C in (S4) and the transmission to node C in (S5), and the transmission to node C in (S4) succeeds. It is fully conceivable that the transmission to (S5) C will fail.

  In the example of FIG. 4 and FIG. 5, since the number of hops is small, the occurrence of change in communication environment is limited to the time zone between (S4) C-directed transmission and (S5) C-directed transmission If the time zone of interest is more extended. An example of the multi-hop case will be described with reference to FIG.

  (S6) The node A detects a timeout of reception waiting time of the route collection frame (return route).

  Transmission was successful from node A to node C to node D according to the information obtained in S3 and S4, and a timeout of reception waiting time was detected in S6 (a route collection frame from node E has not been received Because of that, node A can make the following determination. That is, it can be seen that node A fails in transmission at node D → node E.

  Although the above example is described based on an example in which the number of hops is small, in actual operation, it may be assumed that forwarding by the relay node is several tens of hops. Therefore, there is a possibility that the route collection frame itself which each node on the route loops back to the node of the transmission origin of the route collection may disappear. However, since return frames use a route with the latest communication results, there is a low possibility that all return frames will be lost, and an intermediate route to the final destination can be obtained by analyzing each return frame that has reached the source node. It is possible to trace

  The trace route frame is intermittently transmitted for maintenance with respect to the transmission of a normal frame. This can be used, for example, so as not to affect transmission and reception of a normal frame that collects sensor values obtained by sensors mounted on nodes.

  FIG. 6 shows an example of trace route operation in the case where the number of hops is large in the present embodiment. In FIG. 6, it is assumed that node A wants to acquire the route from node A to node Z, but the packet can reach only node X and the backtracking packet is lost among nodes F to E. .

  First, node A adds route information (transmission result for node B = success) to the route collection frame. The node A transmits a route collection frame to which the route information is added to the node B (S11).

  When receiving the route collection frame from node A, node B adds route information (transmission result for node C = success) to the received route collection frame. The node B transmits, to the node C, a route collection frame to which the route information has been added (S12). At this time, the node B transmits, to the node A, the same frame (loopback frame) as the route collection frame transmitted to the C (S12a).

  The node C, upon receiving the route collection frame from the node B, adds route information (transmission result for node D = success) to the received route collection frame. The node C transmits, to the node D, the route collection frame to which the route information is added (S13). At this time, the node C transmits, to the node A, the same frame (loopback frame) as the route collection frame transmitted to the D (S13a).

  Similarly, after receiving the route collection frame, each node adds the route information to the received route collection frame, and transmits the route collection frame to which the route information is added to the next pop node (S14 to S20). ). At the same time, each node transmits, to node A, the same frame (loopback frame) as the route collection frame transmitted to the next hop node (S14a to S20a).

  When receiving the route collection frame from the node W, the node X adds route information (transmission result for node C = success) to the received route collection frame. The node X transmits a route collection frame to which the route information is added to the node Y (S21). However, in this example, it is assumed that transmission of the route collection frame to the node Y has failed. At this time, the node X transmits, to the node A, the same frame (loopback frame) as the path collection frame transmitted to the Y (S21a).

  If one path is broken, the node X confirms with another path (S21 ', S21 "). The transmitted route collection frame does not reach the node Y, and is addressed to the other node (Y', Y ''). Also, if X does not reach the node X, after detecting a time out, adds path information (transmission result for node W = success) to the received path collection frame. , And transmit to the node W (backtrack) (S22) In S22 and later, the route collection frame is referred to as a backtrack frame.

  When the node W receives the backtrack frame from the node X, it adds path information (transmission result for node V = success) to the received backtrack frame. The node W transmits the backtrack frame to which the path information is added to the node V (S23).

  Similarly, when the backtrack frame is received, each node adds the path information to the received backtrack frame, and transmits the backtrack frame to which the path information is added to the next pop node (S24 to S27). ).

  Here, time may have passed since the previous communication, and communication may become impossible due to a change in radio wave conditions or the like. It is assumed that the backtrack frame is lost due to the communication failure between the nodes E and F (S28).

  However, even if the backtrack does not return in this way, the transmission source node A can acquire the route information up to the middle by the return frame transmitted in S12a to S21a. It is possible to narrow down to the area.

  According to FIG. 6, even if a frame loss occurs in the period T2, the transmission source node can confirm how far the route search frame has reached by receiving the return frame. As a result, it is possible to narrow down the lost paths of the route collection frame.

(Example)
FIG. 7 shows an example of the format of an ad hoc control data frame in the present embodiment. The ad hoc control data frame (hereinafter referred to as "data frame") includes an ad hoc header, a security header, a data header, an ad hoc message (AM) header, and an ad hoc message.

  The ad hoc header includes information such as a local destination address (LD), a local source address (LS), a type, and a frame size. The Hello frame also includes an ad hoc header, and the data frame and the Hello frame are identified by the type value. For example, type 1 is set for data frames, and type 0 is set for hello frames.

  The data header includes a global destination address (GD), a global source address (GS), a frame identifier (frame identifier, FID), an HTL (hop to live), the number of hops, and the like. The frame identifier is an identification number assigned to each ad hoc frame. HTL is a value representing the expiration date of a data frame. Each time a frame is transferred between adjacent nodes, the value of HTL is decremented by one.

  The AM header contains type, subtype. The type is information identifying the type of function or application of the ad hoc control data frame. For example, when “Trace Route” is set as the type, the data frame has a function related to collection of route information and the like.

  A subtype is information that further specifies the function or application set in the “type”. For example, when the subtype is set to “0x00 (collection)”, it indicates that the data frame is a route collection frame used for collecting route information. If the subtype is set to “0x02 (folded back)”, it indicates that the data frame is a folded frame.

  An ad hoc message corresponds to a data payload. In the ad hoc message, transmission results for the next hop node are accumulated and set.

  FIG. 8 is a hardware configuration example of a node in the present embodiment. The node 11 includes a central processing unit (CPU) 12, a wireless communication interface (I / F) 13, a random access memory (RAM) 14, and a non-volatile memory 15. The CPU 12 is connected to the wireless communication I / F 13, the RAM 14, and the non-volatile memory 15 by a predetermined bus.

  The CPU 12 is responsible for various calculation processes. The CPU 12 reads a program for realizing processing to be described later stored in the non-volatile memory 15 or the like, and executes the program. The nonvolatile memory 15 is, for example, a semiconductor memory such as a ROM (Read Only Memory) or a readable and writable SSD (Solid State Drive). The RAM 14 is a volatile memory that temporarily holds data.

  The wireless communication I / F 13 is hardware that performs processing for wireless LAN (Local Area Network) connection. The wireless communication I / F 13 includes, for example, an antenna, an analog-to-digital converter (ADC), a digital-to-analog converter (DAC), a modulator, a demodulator, and the like.

  The node 11 also carries a rechargeable battery as a power supply for supplying power to these electronic components for operation. Although not shown, the node 11 includes a clock or timer for clocking.

  The program for realizing the processing described in the embodiments to be described later may be stored in a storage device such as the non-volatile memory 15 from the program provider side via the communication network. Further, a program for realizing the processing described in the embodiment to be described later may be stored in a commercially available portable storage medium. In this case, the portable storage medium may be set as a reader, and the program may be read and executed by the CPU 12.

  FIG. 9 is an example of a functional block diagram of a node related to frame transmission and reception in the present embodiment. The non-volatile memory 15 stores a routing table 31, a link table 32, a target node addressed (TND) routing table 33, transmission source (LS) node information 34 and the like.

  Although the routing table 31, the link table 32, the TND routing table 33, and the transmission source (LS) node information 34 are stored in the non-volatile memory 15 in the present embodiment, the present invention is not limited thereto. It is also good.

  The wireless communication I / F 13 includes a receiving unit 26 and a transmitting unit 27 and performs processing for communicating with another node. The receiving unit 26 receives the signal of the frame transmitted to the node 11, and outputs the received signal to the frame reception processing unit 21.

  The CPU 12 reads a program stored in the non-volatile memory 15 or the like, and functions as a HELLO control unit 25, a frame transmission processing unit 22, a frame reception processing unit 21, a routing unit 23, and an application processing unit 24.

  The frame reception processing unit 21 converts the signal input from the receiving unit 26 into a frame so that the routing unit 23 can process the signal. The frames obtained by the conversion of the frame reception processing unit 21 include a route collection frame, a control frame other than the route collection frame, and a data frame storing user data. The frame reception processing unit 21 outputs the obtained frame to the routing unit 23.

  When the frame addressed to the node 11 is input from the routing unit 23, the application processing unit 24 processes the input frame by an application program. The application processing unit 24 can also generate a data frame to be transmitted to another node 11 by the processing of the application program. The application processing unit 24 outputs the generated data frame to the routing unit 23.

  The routing unit 23 determines whether the destination (LD) of the input frame is addressed to a node on which the routing unit 23 is mounted or to another node. Then, when the destination (LD) of the frame is addressed to the node on which the routing unit 23 is mounted, the routing unit 23 uses the information registered in the routing table 31 to select any adjacent node (LD). Determine whether to transfer to).

  The routing unit 23 registers the transmission source of the received HELLO message in the routing table 31 based on the ad hoc header included in the input frame. Also, using the node information included in the received HELLO message, the path quality and the communication quality of the inter-node link are calculated, and the result is registered in the routing table 31 or the link table 32. The routing unit 23 controls the transmission unit 27 to transmit a frame including information registered in the routing table 31 and the link table 32.

  When the routing unit 23 receives the route collection frame, the routing unit 23 extracts the local source address (LS) from the route collection frame, and uses the extracted local source address (LS) as the transmission source (LS) node information 34 in the non-volatile memory 15. Store.

  The routing unit 23 generates a route collection frame in which the result of transmission to the node of the next hop (default value = success) is added to the received route collection frame to the next hop (next stage) node. At the same time, the routing unit 23 generates a return frame having the same route information as the generated route collection frame, addressed to the preceding hop node. The generated frame is transmitted via the transmission unit 27.

  After transmitting a route collection frame to which the next hop node-directed transmission result (default value = success) is added to the next hop (next stage) node, after receiving the reception confirmation (ACK) frame corresponding to that transmission The routing unit 23 identifies the communication status with the adjacent node. That is, when the reception confirmation (ACK) frame can be received, the routing unit 23 specifies that the communication with the adjacent node is successful, that is, the communication status is good. On the other hand, when the reception confirmation (ACK) frame can not be received, the routing unit 23 identifies failure in communication with the adjacent node, that is, the communication status is bad.

  The routing unit 23 controls to transfer the return frame to the LS stored as the transmission source (LS) node information 34 when receiving the return frame from another node.

  The HELLO control unit 25 generates a HELLO message frame using the information registered in the routing table 31 and outputs the HELLO message frame to the frame transmission processing unit 22. The HELLO control unit 25 can generate a hello frame including information on the route included in the routing table 31.

  The frame transmission processing unit 22 controls the transmission unit 27 to transmit a frame.

  FIG. 10 shows an example of the link table in the present embodiment. Each node has a link table 31 for nodes adjacent to itself. The node adjacent to itself indicates a node that performs ad hoc communication with itself. When each node receives a Hello message frame from a node adjacent to itself, each node generates a link table 31 for the node that has sent the Hello message frame.

  The link table 31 includes data items of "local sender address (LS)", "aging timer", and "HELLO and received radio related parameters".

  The “local origination address (LS)” stores the address of the sender of the hello message frame, that is, the local origination address included in the ad hoc header of the hello message frame received from the adjacent node.

  The “aging timer” is information for adjusting the timing of deleting the link table 31 and a default value is set when the link table 31 is created.

  The “HELLO and received radio wave related parameter” stores information included in various headers of the Hello message frame received from the adjacent node, the strength (or communication quality) of the received radio wave, and other received radio wave related parameters. Each node transmits information including the communication quality of radio waves received from other nodes in a Hello message frame. The node refers to the Hello message frame received from the other node device to calculate the communication quality of the adjacent node, and the information related to the calculated reception strength (or communication quality) is calculated in “HELLO and reception radio related parameters”. Hold.

  FIG. 11 shows an example of a routing table in the present embodiment. The routing table 32 is a table that holds routing information for adjacent nodes managed in global destination address (GD) units, and is generated for each global destination address. Each node generates the routing table 32 using the link table 31 generated from the Hello message frame received from the adjacent node.

  The routing table 32 can record one or more arbitrary number of local destination addresses (LD) for one global destination address (GD). The routing table 32 records, for each combination of global destination and local destination, information representing the quality of the route calculated using, for example, the number of hops of the route and the received radio wave strength of each link included in the route. Can.

  FIG. 12 shows an example of the TND routing table in the present embodiment. The TND routing table 33 includes data items of "global destination address (GD)", "route collection start time", and "halfway route information".

  The "global destination address (GD)" stores the ID of the target node. The date and time when the route collection frame was sent is stored in the “route collection start time”.

  The “midway route information” stores midway route information obtained from the return frame transmitted from the relay node that has received the route collection frame. More specifically, the intermediate route information is the accumulation of the transmission results for the next hop node provided by each relay node from the node adjacent to the source transmission source (GS) node to the node that has sent the return frame. It is information.

  FIG. 13 shows an example of updating the TND routing table in the present embodiment. At S3 in FIG. 4, the node C transmits a return frame including transmission results for the nodes B, C, and D to the node A which is the transmission source. When node A receives the return frame, node A registers it in the TND routing table, as shown in FIG. 13 (A).

  Next, at S4 in FIG. Send a return frame including the transmission result for E. When node A receives the return frame, node A updates the TND routing table as shown in FIG. 13 (B).

  In this case, in S5 and S6 of FIG. 4, the node A can not receive the route collection frame (return route). However, even if the node A detects a reception timeout, it can be seen that the route collection frame (return) has not been received, and the TND routing table 33 has reached node D because of the state of FIG. .

  Next, processing of a node (starting point node) serving as a starting point of transmitting a route collection frame to a target node will be described using FIGS. Note that the origin node and the target node can be any node.

  FIG. 14 shows the transmission processing flow of the route collection frame (forward path) of the start point node in the present embodiment. The origin node acquires path collection instruction information for collecting the path information to the target node transmitted from the terminal of the user by the operation of the user (S31). The node ID of the target node is specified in the route collection instruction information.

  The origin node acquires from the routing table 32 adjacent nodes that can be transmitted to the target node (S32). Here, the origin node acquires, from the routing table 32, the LD (node ID of the adjacent node) included in the entry in which the designated target node is GD. When a plurality of LDs can be acquired, for example, the origin node acquires the LD with the best communication quality.

  In S32, when the adjacent node of the transmission destination can be acquired from the routing table 32 (“YES” in S33), the start point node generates a route collection frame (for forward route). Here, the origin node sets “type = Trace Route” and “subtype =“ 0x00 ”(collection)” in the AM header of the generated data frame. Also, the origin node assigns the transmission result (default value = “success”) for the adjacent node (next pop node) of the transmission destination to the route collection frame (for forward route) (S34).

  The origin node transmits the route collection frame to which the transmission result (default value = “success”) is given to the transmission destination adjacent node (next pop node) (S35). At this time, the origin node holds the frame identifier included in the data header of the route collection frame (for forward route) in order to determine the route collection frame (for reverse route) corresponding to the route collection frame (for forward route).

  At this time, the origination node measures an ACK for measuring a predetermined time before receiving a reception acknowledgment (ACK) frame notifying that the transmission destination adjacent node (next pop node) has received the transmitted route collection frame. The reception waiting timer is activated (S36).

  Also, the origin node starts a timer that measures the waiting time until receiving the route collection frame (for return route) (S37).

  If the ACK frame for transmission of the route collection frame is not received from the adjacent node within the predetermined time measured by the ACK reception waiting timer ("NO" in S38), the originating node detects timeout of ACK reception waiting time. (S39). In this case, in S34, the origin node updates the transmission result for the next pop node assigned to the path collection frame to "failure" (S40).

  In S38, when the ACK frame for transmission of the route collection frame is received from the adjacent node within a predetermined time measured by the ACK reception waiting timer (“YES” in S38), the originating node performs ACK reception waiting timer It stops (S41). Then, the start point No is in a state of waiting for reception of the route collection frame (for return route) (S42).

  In S33, when the adjacent node of the transmission destination can not be acquired from the routing table 32 ("NO" in S33), the originating node transmits a response indicating failure in route collection to the terminal of the user as a response to the route collection instruction. (S43).

  FIG. 15 shows the reception processing flow of the return frame of the origin node in the present embodiment. The origin node receives the data frame (S51). The origin node determines whether the received data frame is a wrap around frame. If “type = Trace Route” and “subtype =“ 0x02 ”(loopback)” in the AM header of the received data frame, the origin node determines that the received data frame is a loopback frame, and after S52 Perform the processing of

  When the return frame is received, the start node determines whether or not it is in a state of collecting route information (S52). When the route collection frame (for return route) reception waiting timer (S37 in FIG. 14) is activated, the start point node determines that it is in the state of collecting route information.

  If the state is not in the process of collecting route information ("NO" in S52), the start node performs the process of S54.

  When it is in the state of collecting the route information (“YES” in S52), the start point node updates the TND routing table 33 using the route information on the way included in the return frame as described in FIG. (S53).

  The origin node waits for receiving a route collection frame (for return route) (S54).

  FIG. 16 shows the reception processing flow of the route collection frame (for return route) of the start point node in the present embodiment. The origin node receives the data frame (S61). The origin node determines whether the received data frame is a route collection frame (for return). If the frame identifier included in the data header of the received data frame is the frame identifier held in S35 of FIG. 14, the originating node determines that the received data frame is a route collection frame (for return path), and the process proceeds to S62. Perform the following processing.

  When the route collection frame (for return route) is received, the origination node determines whether it is in a state of collecting route information (S52). When the route collection frame (for return route) reception waiting timer (S37 in FIG. 14) is activated, the start point node determines that it is in the state of collecting route information.

  If the state is not in the process of collecting route information ("NO" in S62), the start node performs the process of S67.

  If it is in the state of collecting route information ("YES" in S62), the origination node stops the route collection frame (for return route) reception waiting timer (S63).

  The origin node clears the TND routing table 33 (S64). The origin node extracts information about a relay node that relays communication between the origin node and the target node from the received route collection frame (for return path). The origin node generates route information for the target node based on the extracted information about the relay node (S65). The origin node transmits the generated route information to the terminal of the user as a response to the route collection instruction (S66).

  The origin node waits for receiving the route collection frame (for return route) (S67).

  FIG. 17 shows a processing flow when the reception waiting time of the route collection frame (for return path) of the start point node in this embodiment times out.

  If the time measured by the route collection frame (for return route) reception waiting timer activated in S37 of FIG. 14 exceeds a predetermined time, the start node detects timeout of the route collection frame (for return route) reception waiting time (S71 ).

  The origin node determines whether or not it is in the state of collecting route information (S72). When the route collection frame (for return route) reception waiting timer (S37 in FIG. 14) is activated, the start point node determines that it is in the state of collecting route information.

  If it is not in the state of collecting route information ("NO" in S72), the origin node ends this flow.

  If it is in the state of collecting route information ("YES" in S72), the originating node acquires a TND routing table for the target node (S73). The origin node transmits “GD”, “route collection disclosure time”, and “progress route information” in the obtained TND routing table to the terminal of the user as a response to the route collection instruction (S 74).

  Next, processing of a node (relay node) that relays communication between the start point node and the target node will be described using FIGS.

  FIG. 18 shows a flow of processing for receiving a route collection frame (for forward route) of the relay node in the present embodiment. The relay node receives the data frame (S81). The relay node determines whether the received data frame is a route collection frame (for forward route). If “type = Trace Route”, “subtype =“ 0x00 ”(collection)” in the AM header of the received data frame, and the frame identifier identical to the frame identifier is not held, the origin node is the next Do the processing. That is, the start point node determines that the received data frame is a route collection frame (for forward route), and performs the processing of S82 and thereafter.

  When receiving the route collection frame (for forward route), the relay node transmits an ACK frame to the adjacent node (transmission source (LS)) that has transmitted the route collection frame (for forward route) (S82).

  The relay node holds the node ID of the adjacent node (transmission source (LS)) as transmission source (LS) node information 34 (S83).

  The relay node acquires from the routing table 32 adjacent nodes that can be transmitted to the target node (S84). Here, the relay node acquires, from the routing table 32, the LD (node ID of the adjacent node) included in the entry of the GD corresponding to the GD included in the received route collection frame (for forward route). When a plurality of LDs can be acquired, for example, the relay node acquires the LD with the best communication quality.

  In S84, when the adjacent node of the transmission destination can be acquired from the routing table 32 (“YES” in S85), the relay node generates a route collection frame for forwarding (for forward route). Here, the relay node sets “type = Trace Route” and “subtype =“ 0x00 ”(collection)” in the AM header of the generated data frame. Also, the origin node assigns the transmission result (default value = “success”) addressed to the transmission destination adjacent node (next pop node) to the generated route collection frame (for forward route) (S86).

  The relay node transmits the route collection frame to which the transmission result (default value = “success”) is given to the transmission destination adjacent node (next pop node) (S87). At this time, the relay node holds the frame identifier included in the data header of the route collection frame (for forward route) in order to determine the route collection frame (for return route) corresponding to the route collection frame (for forward route).

  Furthermore, the relay node generates a return frame, and transmits the generated return frame to the transmission source (LS) held in S83 (S88). Here, the relay node generates a loop back frame as follows. The relay node acquires the node ID of the source node (GS) from the route collection frame to which the transmission result (default value = “success”) is generated, which is generated in S86. In the route collection frame, the relay node sets the node ID of the source node in GD, sets the transmission source (LS) acquired from the node information 34 in LD, and sets “type = Trace Route” in the AM header, “sub Set the type = "0x02" (wrapping).

  The relay node waits for an ACK reception waiting timer that measures a predetermined time before receiving an acknowledgment (ACK) frame notifying that the adjacent node (next pop node) of the transmission destination has received the transmitted route collection frame. (S89).

  When the relay node does not receive the ACK frame for transmission of the route collection frame at S87 from the adjacent node within the predetermined time measured by the ACK reception waiting timer (“NO” at S90), the relay node A timeout is detected (S91). In this case, the relay node determines that the communication status with the adjacent node is bad, and updates the transmission result for the next pop node assigned to the route collection frame in S86 to "failure" (S92).

  In S90, when an ACK frame for transmission of a route collection frame (for forward route) is received from the adjacent node within a predetermined time measured by the ACK reception waiting timer ("YES" in S90), the relay node It is determined that the communication status with the adjacent node is good. In this case, the relay node stops the ACK reception waiting timer (S93).

  In S85, when the adjacent node of the transmission destination can not be acquired from the routing table 32 ("NO" in S85), the relay node acquires the transmission source (LS) from the transmission source (LS) node information 34 (S94) ).

  The relay node generates a backtrack frame, and transmits the generated backtrack frame to the transmission source (LS) acquired from the transmission source (LS) node information 34 (S95). Here, the relay node generates a backtrack frame as follows. The relay node acquires the node ID of the source node (GS) from the route collection frame received in S81. The relay node sets the node ID of the start node in GD in the route collection frame, and sets the transmission source (LS) acquired from the node information 34 in LD.

  Although FIG. 18 describes the process in the case of receiving a route collection frame (for forward route), the process in the case of receiving a route collection frame (for return route) is the same as that in FIG. That is, in the description of FIG. 18 described above, the route collection frame (for forward route) may be read as the route collection frame (for return route).

  FIG. 19 shows the reception processing flow of the return frame of the relay node in the present embodiment. The relay node receives the data frame (S101). The relay node determines whether the received data frame is a wraparound frame. If “type = Trace Route” and “subtype =“ 0x02 ”(loopback)” in the AM header of the received data frame, the relay node determines that the received data frame is a loopback frame, and after S102 Perform the processing of

  When the return frame is received, the relay node acquires the transmission source (LS) from the transmission source (LS) node information 34 (S102).

  The relay node sets the transmission source (LS) from the transmission source (LS) node information 34 to the LD of the received return frame. The relay node transmits the return frame to the transmission source (LS) acquired from the transmission source (LS) node information 34 (S103).

FIG. 20 shows a reception processing flow of backtrack frames of the relay node in the present embodiment. The relay node receives the data frame (S111). The relay node determines whether the received data frame is a backtrack frame.
If the relay node holds the same frame identifier as the frame identifier of the data header of the received data frame, and the transmission result for the next-pop node given last is set as “failure”, the relay node It is determined that it is a backtrack frame. In that case, the relay node performs the processing of S112 and thereafter.

  When receiving the backtrack frame, the relay node acquires the transmission source (LS) from the transmission source (LS) node information 34 (S112).

  The relay node sets the transmission source (LS) from the transmission source (LS) node information 34 to the LD of the received backtrack frame. The relay node transmits the backtrack frame to the transmission source (LS) acquired from the transmission source (LS) node information 34 (S113).

  Although the process in the case of receiving the backtrack frame has been described in FIG. 20, the relay node may execute the flow of FIG. 20 also in the case of receiving the route collection frame (for return path).

  According to the present embodiment, each node in the middle of the route relays the frame and transmits the route information frame to the transmission start address. By notifying the arrival to the relay node with this path information frame, the transmission start node can obtain the path information up to the middle even if the frame is lost on the way. Thus, it is possible to immediately identify the path in which the communication failure has occurred.

  Therefore, even in the case of a communication failure in which a frame is lost along the route, events can be monitored in real time, so early maintenance of the corresponding wireless section becomes possible. Further, in the present embodiment, it is possible to identify the path that is the cause by performing frame transmission specifying the final arrival node. Therefore, since it is not necessary to limit to a specific maintenance person, efficient investigation becomes possible, and the reduction effect of investigation man-hour can be expected.

  The present invention is not limited to the embodiments described above, and various configurations or embodiments can be taken without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 relay apparatus 2 receiver part 3 transmitter part 4 memory part 5 identification part 11 node 12 CPU
13 Wireless Communication I / F
14 RAM
DESCRIPTION OF SYMBOLS 15 Non-volatile memory 21 Frame reception process part 22 Frame transmission process part 23 Routing part 24 Application process part 25 HELLO control part 26 Reception part 27 Transmission part 31 Routing table 32 Link table 33 TND routing table 34 Source (LS) node information

Claims (6)

In a node device included in a plurality of node devices constructing a communication network from a data transmission source to a data transmission destination,
The communication information which is transmitted from the data transmission source first and which has the information on the communication path from the data transmission source to the node device, the communication information having the data transmission destination as the final destination , Received from the previous node device in the communication path ,
Communication information obtained by adding identification information of a subsequent node device in the communication route to the data transmission destination of the communication information to information of the communication route included in the received communication information, the latter node device Send to
The communication information of the return, which is the communication information having the same communication path information as the communication information transmitted to the node device in the subsequent stage and having the same data transmission source as the final destination, Send to the node device of
A route information collecting program characterized by executing a process. Furthermore, in the node device,
When the communication information is received from the preceding node device, the identification information of the preceding node device is held in the storage device.
When the communication information of the return is received from the node apparatus of the subsequent stage , the received communication information of the return is transmitted to the node apparatus of the previous stage using the stored identification information. The route information collection program described in 1 . Furthermore, in the node device,
A process of specifying the communication status between the node devices of the communication path is executed based on the reception confirmation information for the communication information transmitted to the node devices of the subsequent stage received from the node device of the subsequent stage. The route information collecting program according to claim 1 or 2 . Furthermore, in the node device,
When receiving the communication information having the communication route from the first transmission source of the communication information to the node device, the communication information having the data transmission source as the final destination from the node apparatus of the subsequent stage Communication information obtained by adding identification information of the node device of the preceding stage to information of a communication path included in the communication information received from the node device of the subsequent stage is transmitted to the node device of the preceding stage;
The route information collecting program according to any one of claims 1 to 3, wherein the processing is executed. Node device included from a data source to a plurality of node devices to build a communication network to a data transmission destination,
The communication information which is transmitted from the data transmission source first and which has the information on the communication path from the data transmission source to the node device, the communication information having the data transmission destination as the final destination , Received from the previous node device in the communication path ,
Communication information obtained by adding identification information of a subsequent node device in the communication route to the data transmission destination of the communication information to information of the communication route included in the received communication information, the latter node device Send to
The communication information of the return, which is the communication information having the same communication path information as the communication information transmitted to the node device in the subsequent stage and having the same data transmission source as the final destination, Send to the node device of
Wherein the data transmission source device, the route information collection method characterized by collecting the communication information of the folded transmitted from said plurality of node devices. A node device included in a plurality of node devices constructing a communication network from a data transmission source to a data transmission destination,
The communication information which is transmitted from the data transmission source first and which has the information on the communication path from the data transmission source to the node device, the communication information having the data transmission destination as the final destination , A receiving unit that receives from a node apparatus in a preceding stage of the communication path ;
Communication information obtained by adding identification information of a subsequent node device in the communication route to the data transmission destination of the communication information to information of the communication route included in the received communication information, the latter node device And communication information which has the same communication path information as the communication information transmitted to the subsequent stage node apparatus and which is the communication information whose final destination is the data transmission source A transmitter configured to transmit information to the preceding node apparatus ;
A node device comprising:

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