JP2009071683A - Node and radio communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a node and radio communication system reducing the transfer load of a certain node through a simple process. <P>SOLUTION: The node of this invention transmits a packet received from another node or transmission packet whose transmission source is itself through radio transmission. In this case, the node is provided with: a neighborhood node information storing means for storing the information of the neighborhood node capable of extending a link by own node; and a link point determining means which determines whether a shortcut pass with respect to a transmission route, determined by the final address node of the transmission packet and the topology of a network, can be set based on the storing information of the neighborhood information storing means and when the setting is possible, the other node with respect to the shortcut pass is set on the radio link point but when the setting is impossible, the next other node is set on the radio link point on a determined transmission route. The radio communication system of this invention is provided with a plurality of nodes of this invention. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a node and a wireless communication system, and can be applied to packet transfer in a wireless packet network having a cluster tree topology such as ZigBee.

  In ZigBee, a star type, a cluster tree type (hereinafter simply referred to as a tree type), and a mesh type topology are defined (see Non-Patent Document 1). Among these three methods, the tree type topology can simplify the routing calculation and can easily form a large-scale network.

  In ZigBee, the maximum number of hierarchies Lm from the coordinator, the maximum number of child nodes Cm, and the maximum number of child routers Rm are defined in the network. From these three parameters, the network address of the node added to the tree topology network can be calculated. Network addresses are assigned in the form of where they are in the tree. By doing so, each node can compare the destination network address with the network address of its own node and forward the packet in either the parent (parent node) or child (child node) direction of the tree. You can decide whether it ’s good.

Cskip (d) shown in the equation (1) is a calculation formula for the skip interval for address assignment to nodes in the hierarchy d + 1 (see Non-Patent Document 2).

  FIG. 2 shows an example of network address assignment to each node in a tree topology. FIG. 2 shows an example of a two-level tree structure from the coordinator (tree root node) RT. The network address “000” is assigned to the coordinator RT, and “100”, “200”, and “300” are assigned to the three nodes N1 to N3 immediately below the coordinator RT with a skip interval “100”, respectively. It has been. Two nodes N11 and N12 immediately below the node N1 with the network address “100” are assigned “110” and “120” as network addresses with a skip interval “10”, respectively. There may be a node located in a hierarchy below this second hierarchy. The node N1 with the network address “100” transfers the received packets whose destination network addresses are “101” to “199” to the child side of the tree (the lower layer side related to itself). When a packet with a destination network address other than that is received, the received packet is transferred to the parent RT (upper layer side) node RT. As described above, in the tree topology, each node can easily determine the packet transfer destination.

For example, as shown in FIG. 3, the packet from the node N11 to the node N21 is transferred to the upper node (coordinator) RT based on the first numeral “2” of the destination network address “210”. The node RT transfers to the node N2 based on the first digit “2” of the destination network address “210”, and the node N2 transfers the node N21 based on the two-digit number “21” on the first side of the destination address “210”. Forward to.
By Tatetsu, “ZigBee Development Handbook”, published by Rick Telecom, February 2006, pp. 109-114 Taehong Kim et al. , “Shortcut Tree Routing in ZigBee Networks”, IEEE International Symposium on Wireless Pervasive Computing, 2007.

  However, in the tree type topology, packets to nodes located in a branch different from the self node among a plurality of branches branched from the node located on the upper side of the own node pass through the parent side node, Since it is transferred to the destination node of another branch, there is a problem that a node closer to the root of the tree has to execute transfer processing of more packets, and the load is larger. It is considered that the transfer load of the coordinator is the largest.

  Although it is possible to distribute the load by using a mesh topology, each node needs to have a routing table, and there is a problem that the implementation cost is higher than that of a tree topology.

  Non-Patent Document 2 refers to a method of shortcuting the original path in the tree topology, but the calculation of the evaluation value for determining whether or not to perform the shortcut is complicated.

  Therefore, a node and a wireless communication system that can reduce the transfer load of a certain node by simple processing are desired.

  In the first aspect of the present invention, in a node that wirelessly transmits a packet received from another node or a transmission packet having itself as a transmission source, (1) a packet of a neighboring node is intercepted and the node can establish a link. Neighboring node information storage means for storing information on possible neighboring nodes, and (2) whether or not a shortcut path for a forwarding path determined from the final destination node of the transmission packet and the network topology can be set. Judgment based on the information stored in the information storage means, when it can be set, the other node related to the shortcut path is determined as a wireless link destination, and when it cannot be set, the next other node on the determined transfer route is wireless And a link destination determining means for determining the link destination.

  A radio communication system according to a second aspect of the present invention includes a plurality of nodes according to the first aspect of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the node and radio | wireless communications system which can reduce the transfer load of a certain node by simple processing are realizable.

(A) First Embodiment Hereinafter, a first embodiment of a node and a wireless communication system according to the present invention will be described in detail with reference to the drawings.

(A-1) Configuration of the First Embodiment The wireless communication system according to the first embodiment is also a ZigBee network to which a tree type topology is applied. An outline of the ZigBee network assumed in the first embodiment will be briefly described with reference to FIG. 2 used in the background art section.

  Node RT is a coordinator. When nodes N1, N2, N3,... Located in the vicinity of the coordinator RT (network address “000”) join the network, the coordinator RT sets the network address such as “100”, “200”, “300”,. assign. When nodes N11, N12,... Located in the vicinity of the node N1 (network address “100”) join the network, network addresses such as “110”, “120”,. In this way, a network topology as shown in FIG. 2 is formed. In FIG. 2, a line connecting the nodes represents a wireless link, and each node transfers a packet to any one of the nodes connected by the line.

  In the first embodiment, depending on a destination node (its network address), a part of the nodes can transfer a packet other than nodes connected by a line.

  FIG. 1 is a block diagram illustrating a detailed functional configuration of some nodes according to the first embodiment. A node having the detailed configuration shown in FIG. 1 is a node that is neither an end node nor a coordinator. In other words, FIG. 1 shows a detailed configuration of a node excluding a coordinator among nodes that perform packet relay (transfer). Note that the end node may have the detailed configuration shown in FIG. 1 as long as it becomes a node that can be relayed in the future. For example, if FIG. 2 shows the overall configuration of the network, the nodes N1 to N3 have the detailed configuration of FIG.

  In FIG. 1, a node 100 (N1 to N3) includes a packet receiving unit 101, a link information analyzing unit 102, a network information analyzing unit 103, an application (application program) 104, an adjacent table 105, a route determining unit 106, and a route changing unit 107. A packet generation unit 108 and a packet transmission unit 109. The link information analysis unit 102, the network information analysis unit 103, the adjacency table 105, the route determination unit 106, the route change unit 107, and the packet generation unit 108 may be realized by software.

  The packet receiving unit 101 receives a wireless packet transmitted by an adjacent node and gives it to the link information analyzing unit 102.

  The link information analysis unit 102 confirms the destination address (destination data link address) in the data link layer of the received packet, gives it to the network information analysis unit 103 if it is addressed to the node 100, and receives it if it is not addressed to the node 100. The packet is discarded. In addition, the link information analysis unit 102 determines whether or not information of a node having a transmission source address in the data link layer of the received packet (not only the original transmission source but also a relay source) exists in the adjacent table 105. (Including the case where the received packet is discarded as described above), and if the information of the transmission source node of the received packet is not stored in the adjacency table 105, the node information is added to the adjacency table 105 Is.

  The network information analysis unit 103 determines whether or not the final destination node of the received packet is the node 100. If the node 100 is the final destination node, the received data is given to the application 104 and received. If the final destination node of the packet is another node and the packet is relayed by the node 100, the data is given to the route determination unit 106.

  The application 104 is software that performs data processing (the data processing configuration may be configured by hardware using a DSP or the like), and processes received data provided from the network information analysis unit 103. In addition, as a result of the data processing, data that needs to be transmitted to another node is given to the route determination unit 106.

  The adjacency table 105 is a table that stores information on neighboring nodes of the node 100. In this adjacency table 105, not only the adjoining nodes that are to be linked by the tree topology but also information on neighboring nodes where the node 100 can receive a packet (a radio wave reaches the node) is stored. . The adjacency table 105 is a neighborhood of information such as MAC (Media Access Control) address, PANID (Private Area Network Identifier), network address, node type (coordinator, end node, router), positional relationship (parent, child, same layer), etc. It is stored in node units (see FIG. 6 described later).

  The route determination unit 106 is determined on a tree topology as shown in FIG. 2 for the transmission data that the node 100 is the initial transmission source and the data that is relayed and transmitted from the network information analysis unit 103. The destination node (route) on the wireless link from the node 100 is determined (note that the final destination information is attached to the data). This determination method is based on the method described in the background art section. That is, the route determination unit 106 compares the destination network address with the network address of the node 100 and determines whether to transfer to the parent node or the child node.

  The route changing unit 107 maintains the destination node (route) in the wireless link determined by the route determination unit 106 while referring to the stored contents of the adjacency table 105, or there is a destination node in the wireless link that can shortcut the route. It is a judgment to do. This determination method will be clarified in the operation description.

  The packet generation unit 108 generates a packet addressed to the destination node in the wireless link according to the determination result of the route change unit 107. The packet generation unit 108 takes in the MAC address, PANID, and the like necessary at that time from the adjacency table 105.

  The packet transmission unit 109 radiates the packet generated by the packet generation unit 108 to the wireless space.

(A-2) Operation of First Embodiment Next, the operation of the wireless communication system according to the first embodiment will be described. In particular, the transfer operation of a node that is neither an end node nor a coordinator will be described to clarify the features of the first embodiment.

  Hereinafter, the case where the node N1 relays a packet addressed from the node N11 to the node N21 in FIG. 2 will be described in detail. Incidentally, in the conventional case, as described with reference to FIG. 3, in this case, a packet addressed from the node N11 to the node N21 reaches the node N21 through the route N11-N1-RT-N2-N21. .

  FIG. 4 is a flowchart showing the operation (packet reception, transfer destination determination, packet transmission) of the node 100 having the detailed configuration of FIG. 1, and the node N1 also executes processing according to the flowchart of FIG.

  When the packet receiving unit 10 receives a packet, the node 100 starts a series of processes shown in FIG. 4 (S1).

  After analyzing the transmission source address of the received packet, the link information analysis unit 102 performs an update operation on the information in the adjacency table 105 based on the link transmission source address regardless of whether or not it is addressed to the node 100 ( S2). The update operation includes an operation for determining whether or not to update, and may not be updated. That is, if the node information of the link source address of the received packet is not stored in the adjacency table 105, the node information is added to the adjacency table 105. When adding information to the adjacency table 105, a record including a MAC address, a PANID, a network address, a node type (coordinator, end node, router), a positional relationship (parent, child, same layer) is added. .

  The node type (coordinator, end node, router) is determined based on the network address of the transmission source seen from the radio link of the received packet. For example, if the network address is all “0”, the coordinator RT is determined. If the network address is not all “0” and the value of the first digit (lowest digit) is “0”, it is determined as a router, and the network address is not all “0” but one digit (lowest digit). If the value of the eye is other than “0”, it is determined as an end node. The positional relationship (parent, child, same layer) is determined by comparing the network address of the node 100 with the network address of the transmission source seen from the wireless link of the received packet. “Parent” means a node on the coordinator RT side that can directly transfer a packet, “child” means a node that can transfer a direct packet in the opposite direction to the coordinator RT, and “same layer” means a coordinator RT. Nodes with the same number of hops from Since the network address allocation method described above is employed, such positional relationship information is obtained based on the network address of the node 100 and the network address of the transmission source viewed from the wireless link of the received packet. be able to.

  FIG. 5 shows an example of a radio wave reachable range of the node N1 other than the node that can establish a radio link, and FIG. 6 shows the contents stored in the adjacency table 105 of the node N1 in the case of the radio wave reachable range example of FIG. ing. Note that FIG. 6 omits description of the MAC address and PANID in the information (field) in one record.

  Since the node N1 is a node immediately below the coordinator RT, information on the coordinator RT is described in the adjacency table 105 when the node N1 is connected to the network. Nodes N11 and N12 that are child nodes of the node N1 are also described in the adjacency table 105 when connected to a network to which a network address is assigned. The node N1 also monitors packets other than the packet received by the node N1 and the packet to be relayed. For example, when receiving a packet from the node N2 or the node N21, the adjacent table 10 (Note that depending on the reception of one packet, only one record is added to the adjacency table 105). As for the node N2, the positional relationship is described as “same layer” by receiving the packet to the coordinator RT. It should be noted that at the time of transfer from the coordinator RT to the node N2, the presence of the node N2 in the same layer is recognized (stored in addition to the adjacent table), and the information recognized when the packet is received from the node N2. May be described in the adjacent table 105 as “same layer”.

  As described above, the same layer may be determined based on the destination data link address of the packet transmitted by the coordinator RT, and the number of layers from the coordinator RT can be calculated from the network address. Based on the calculation, the same layer may be determined. If the positional relationship is grasped by calculation based on the network address, the node N21 can be regarded as “a child of the same layer”, and is written in the adjacent table 105 of “the child of the same layer”. Also good.

  When the update operation for the adjacency table 105 is completed, the link information analysis unit 102 checks whether the destination data link address indicates the node 100 (S3). If it is not addressed to the node, the received packet is discarded, and the series of processing shown in FIG. 4 ends.

  If the destination data link address indicates the node 100, the network information analysis unit 103 further checks the destination network address (S4). If the destination network address indicates the node 100, the network information analysis unit 103 extracts the data in the received packet, delivers it to the application 104, and ends the series of processing shown in FIG.

  If the destination network address does not indicate the node 100, the route determination unit 106 determines whether the destination network address is on the child node side as viewed from the node 100 (S5). The transmission data is processed from the step S5 executed by the route determination unit 106. The determination in step S5 is a determination as to whether or not the transfer is in a direction in which cut-through is not performed.

  If the route determination unit 106 determines the transmission direction of the packet to be a child side of the tree, the route change unit 107 does not change the route, and the packet to be transmitted (relay packet or the packet from which the node originally transmitted) Is input to the packet generator 108 (S6). In the packet generation unit 108, the data link address of the child node is used as the destination data link address (if relaying, the destination data link address is rewritten, and if it is a transmission source, the destination data link address is set. For example, if the destination network address is “110”, “110” is set in the destination data link address field of the packet.

  If the route determination unit 106 determines the transmission direction of the packet to be the parent side of the tree, the route change unit 107 describes the node of the destination network address as a node described as the same layer in the adjacency table 10 or the same layer. It is checked whether the node is under the current node (S7). Whether a node is a subordinate node described as the same layer can be determined by calculation from a network address.

  If the node of the destination network address is a node described as the same layer in the adjacent table 10 or a node under the node described as the same layer, the path changing unit 107 sets the data link address of the node as The destination data link address is determined (S8). For example, in the adjacency table 10 of FIG. 6, a node N2 (network address “200”) is described as a node in the same layer. Since the nodes with network addresses “201” to “299” are under the node N2, if the destination network address is within this range “201” to “299”, the destination data link address is set to the data link of the node N2. Set to address.

  On the other hand, if the destination network address is not the network address of a node on the child side of the tree and under the same layer (including the same layer), the path changing unit 107 sets the destination data link address of the parent side node. (S9). For example, when the destination network address is “300”, the destination data link address is set to “000”. For example, when the destination network address is “000”, the destination data link address is set to “000”.

  After the packet generation unit 108 generates a transmission packet having the destination data link address specified in any of steps S6, S8, and S9 and using the data link address of the node 100 as the transmission source data link address, packet transmission Unit 109 transmits the packet to the network (S10).

  As described above, the node 100 is not limited to the neighboring nodes that have a link-related relationship in terms of topology, but is not related to the link-related relationship in the topology, but the nodes in the same layer that are within the radio wave reachable range. Even you can make a link. For example, the node N1 can link not only to the nodes RT, N11, and N12 but also to the node N2. As shown in FIG. 7, the node N1 conventionally forwards the packet to the node under the node N2 to the node N2 via the coordinator RT. However, in the first embodiment, the node N1 directly transfers to the node N2. It can be transferred.

(A-3) Effects of the first embodiment According to the first embodiment, neighboring nodes are registered in the adjacency table based on the reception status from the neighboring nodes and the routing information without being limited to the parent nodes and child nodes. If there is a same layer node registered in the adjacent table on the route to the destination node, the transfer destination is set not to the parent node but to the same layer node. And can be transferred directly to the same layer node.

  Thereby, it is possible to reduce the load of the shortcut node. In addition, the number of pops required for transfer can be reduced, and it can be expected that the transfer time will be shortened. Also, a reduction in network load can be expected.

(A-4) Modified Embodiment of First Embodiment In the above description, the case where the coordinator RT located at the root of the tree is short-cut has been described. However, the same technique as described above can be used when a router node is short-cut. Can be applied.

  For example, using the fact that all the relay nodes on the route can be known from the own network address and the destination network address, the node closest to the destination side among the nodes described in the adjacency table 10 in step S7 A router node shortcut or the like may be realized by transferring to (which may be the destination node itself).

  FIG. 8 is an explanatory diagram of an example of a method for knowing all relay nodes on a route. When transmitting from the node N1 with the network address “100” to the node N21 with the destination network address “210”, the parent of the node N1 is the node with the address “000” and the node RT with the address “000” Located in the most parent. In the same manner, the parent node of the node N21 having the address “210” is the node N2 having the address “200”, and the parent of the node N2 having the address “200” is the node having the address “000”. , The node RT having the address “000” is located at the most parent. For these reasons, in the transfer from the node N1 to the node N21, a route of N1 (100) -RT (000) -N2 (200) -N21 (210) is obtained in the conventional (normal) manner.

  Next, from the end of this route, it is checked whether it is in the adjacency table 105 in order. First, it is checked whether there is node information of the address “210”. In the example of the adjacency table 105 in FIG. 6, since the node having the network address “210” is described, the destination link address of the packet transmitted from the node N1 is set to the link address of the node N21, and the packet is transmitted from the node N1. . If there is no node information of address “210” in the adjacency table 105, it is checked whether there is a corresponding node in the adjacency table 105 in order of the node “200” and the node “000”. The packet is transferred with the link address of the node as the destination link address.

(B) Second Embodiment Next, a second embodiment of the node and the wireless communication system according to the present invention will be described in detail with reference to the drawings.

  FIG. 9 is a block diagram showing a functional detailed configuration of some nodes according to the second embodiment. The same reference numerals are given to the same and corresponding parts as those in FIG. 1 according to the first embodiment. Show.

  In FIG. 9, the node 100A of the second embodiment includes a packet receiving unit 101, a link information analyzing unit 102, a network information analyzing unit 103, an application (application program) 104, an adjacent table 105, a route determining unit 106, and a route changing unit. 107, in addition to the packet generation unit 108 and the packet transmission unit 109, a packet transmission / reception counter 110 is provided.

  The packet transmission / reception counter 110 counts the number of packets transmitted / received in units of links between nodes, and writes information on the number of packets transmitted / received in units of links in the adjacency table 105. The information on the number of transmission / reception for each link stored in the adjacent table 105 is the number of transmission / reception per unit time. However, the present invention is not limited to this, and the number of transmissions / receptions in the latest predetermined time may be used, or the total number from the time of network connection may be used. The packet transmission / reception counter 110 counts not only data packets but also ACK (Acknowledgement) packets. Therefore, when the communication environment of the link is good, the number of transmissions and the number of receptions on the same link match.

  The packet transmission / reception counter 110 counts the number of transmissions / receptions for each link of the link having the node 100A as a transmission source or destination. The packet transmission / reception counter 110 counts the number of transmissions / receptions in the link unit of the link from the parent node of the node 100A to a node in the same layer as the node 100A.

  FIG. 10 shows only information unique to the second embodiment extracted from the adjacency table 105. In the link (AB) column, both end nodes of the link are defined by a combination of network addresses. When A is the node 100A (address “100”), information as shown in FIG. 10 may be included in the record of the neighboring node (B) in FIG.

  For example, the row (record) of “100-000” describes the number of packets transmitted and received between the node 100A having the address “100” and the node (coordinator) having the address “000”. This indicates that the node 100A has transmitted 80 packets and has received 80 packets. Also, for example, the line “000-200” describes the number of packets sent and received between the coordinator with the address “000” and the node with the address “200”. 50 packets are transmitted from the coordinator RT, and the coordinator RT This indicates that 50 packets have been received. The information on the line “000-200” is information obtained by packet interception.

  In the first embodiment, if communication with a node in the same layer is possible, the node to the same layer is used as a transfer destination and a shortcut is performed. However, in the second embodiment, the link quality between nodes is also considered. It was decided to. For example, the route changing unit 107 considers link quality between nodes. Note that the information shown in FIG. 10 may be written in the adjacent table 105 through a link quality stage (good, bad, etc.).

  For example, 20 packets are transmitted and 20 packets are received between the node 100A (N1) having the address “100” and the node N2 having the address “200”. Also, 100 packets are transmitted and 80 packets are received between the node 100A (N1) having the address “100” and the coordinator RT having the address “000”. Therefore, it can be said that the former link quality is better than the latter link quality.

  The route changing unit 107 determines whether or not to perform a shortcut in the same manner as in the first embodiment, and determines a route for performing the shortcut. Then, check the link quality in the shortcut route. In the shortcut from the node 100A (N1) to the node N2 whose address is “200”, the link quality is good, and the link is finally determined.

  The node 100A (N1) having the address “100” and the node N3 having the address “300” transmit 10 packets from the node 100A (N1) and receive only 3 packets. If the value with the larger number of transmissions and the number of receptions as the denominator and the smaller value as the numerator is smaller than a predetermined value (for example, 0.7), it is determined that the link quality is poor. Accordingly, it is determined that the link quality between the node 100A (N1) and the node N3 is poor. In this case, the quality of the link in the route without the shortcut is also confirmed. In the route without the shortcut, the link between the node 100A (N1) and the coordinator RT having the address “000”, the link between the coordinator RT having the address “000” and the node N3 having the address “300” Is a problem. The worse of the two links is compared to the link quality with the shortcut. The coordinator RT with the address “000” and the node N3 with the address “300” transmit 70 packets from the coordinator RT and receive only 20 packets, and the link quality is poor. When the quality is poor both when the shortcut is performed and when the shortcut is not performed, the shortcut is executed in consideration of the load.

  In summary, when executing a shortcut, the route changing unit 107 confirms the link quality in the shortcut. If the quality is good, it is finally decided to shortcut.

  If the link quality with the shortcut is poor, the link quality without the shortcut is captured and compared with the link quality with the shortcut. If the link quality when the shortcut is not used is good, even if the shortcut link exists, it is finally decided not to perform the shortcut. On the other hand, when both the case where the shortcut is performed and the case where the shortcut is not performed are of poor quality, the shortcut is executed in consideration of the load.

  In the above description, the quality is compared as two levels. However, the quality may be compared as three levels or more. Even in this case, the review method based on the comparison between the case where the shortcut is performed and the case where the shortcut is not performed is as described above.

  The link determined to be used for determining whether or not to perform a shortcut may be immediately applied to a similar destination without comparing the details thereof.

  However, since the link quality often changes with time, once the transfer route is set, it may be determined again after a predetermined time and the transfer route is changed.

(B-3) Effects of the second embodiment According to the second embodiment, since the link quality is reflected and it is determined whether or not to use the shortcut path, the shortcut path is rejected. This can be prevented beforehand when it works to increase the load.

  In the ZigBee network, the parent node is determined so that the additional node is subordinate to a neighboring node that can perform good communication. Since such a determination method is adopted, the communication quality (link quality) in the shortcut path may be deteriorated. When such a shortcut path is selected, retransmission may occur frequently and the load on the network may increase. In the second embodiment, whether or not the shortcut path is used in consideration of link quality. Therefore, it is possible to prevent such a problem.

(C) Other Embodiments Although various modified embodiments have been mentioned in the description of each of the above embodiments, further modified embodiments as exemplified below can be given.

  In each of the embodiments described above, a node that is neither an end node nor a coordinator (root node) is provided with a shortcut function. However, the end node may be provided with a shortcut function.

  In each of the above embodiments, the shortcut path is set using the destination or the network address of the node. However, the original route is determined by another method, and the adjacent node information and the original route are determined. The shortcut path may be determined based on the relationship. For example, each node stores topology information (network node, link configuration), determines the original route based on the minimum number of hops, the minimum distance, etc. The shortcut path may be set by the method of the modified embodiment of the embodiment.

  If a method similar to that of such a modification is applied, the present invention is not limited to a tree topology network, but can be applied to networks of other topologies.

  In the above description, the ZigBee network has been described. However, the present invention can be applied to other networks.

  In the first embodiment, the case of determining whether or not to apply a shortcut path each time has been shown. However, once the determined shortcut path is not updated in the neighborhood table, or a network node is added. As long as no notification is received from a coordinator or the like, it may be made valid thereafter.

It is a block diagram which shows the functional detailed structure of the one part node which concerns on 1st Embodiment. It is explanatory drawing which shows the example of allocation of the address to each node in a tree type topology. It is explanatory drawing which shows the example of the transfer route of the packet in a tree type topology. It is a flowchart which shows operation | movement of the one part node which concerns on 1st Embodiment. It is explanatory drawing which shows an example of the electromagnetic wave reachable range to a certain node in 1st Embodiment. It is explanatory drawing which shows the storage content of the adjacent table in the object node of FIG. It is explanatory drawing of the shortcut of the coordinator by 1st Embodiment. It is explanatory drawing of the recognition method of the path | route in the deformation | transformation embodiment of 1st Embodiment. It is a block diagram which shows the functional detailed structure of the one part node which concerns on 2nd Embodiment. It is explanatory drawing of the additional item of the adjacent table in 2nd Embodiment.

Explanation of symbols

  RT ... Coordinator, 100, 100A, N1-N3, N11, N12, N21, N22, N31, N32 ... Node, 101 ... Packet receiver, 102 ... Link information analyzer, 103 ... Network information analyzer, 104 ... Application program , 105 ... adjacency table, 106 ... route determination unit, 107 ... route change unit, 108 ... packet generation unit, 109 ... packet transmission unit, 110 ... packet transmission / reception counter.

Claims (8)

In a node that wirelessly transmits a packet received from another node or a transmission packet having the transmission source as a source,
Neighboring node information storage means for intercepting packets of neighboring nodes and storing information of neighboring nodes that can be linked by the own node;
Whether or not a shortcut path for a transfer route determined from the final destination node of the transmission packet and the topology of the network can be set is determined based on the storage information of the neighboring node information storage means. And a link destination determining means for determining the next other node as the radio link destination on the determined transfer path when the other node is determined as a radio link destination and cannot be set.   The node according to claim 1, wherein the link destination determination unit determines to shortcut the node of the first hop when transfer to the node of 2 hops ahead is possible. The network to which the node belongs applies a tree topology,
2. The node according to claim 1, wherein the link destination determination unit determines a wireless link destination so as to avoid transfer to a parent node by a shortcut path.   4. The node according to claim 3, wherein the link destination determination means calculates the number of hierarchies from the root node of the tree for neighboring nodes, and uses the number of hierarchies for determining the radio link destination. The network to which the node belongs applies a tree topology, and each node is assigned a network address that uniquely identifies the location on the network.
The link destination determination means uses the network address of the own node and the destination network address of the final destination node to obtain information of all other nodes on the transfer route, and to any other node on the transfer route, The node according to claim 1, wherein a wireless link destination is determined.   6. The node according to claim 5, wherein the link destination determining means determines a wireless link destination to another node closest to a final destination node capable of wireless communication among other nodes on the transfer path. It further comprises link quality acquisition management that intercepts many packets of neighboring nodes and acquires and manages quality information for each link,
2. The node according to claim 1, wherein the link destination determination unit determines another node related to the shortcut path as a wireless link destination on condition that the link quality of the shortcut path does not deteriorate as compared with the original path.   A wireless communication system comprising a plurality of nodes according to claim 1.

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