JP2011055394A - Wireless communication apparatus and wireless communication program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain the improvement of communication efficiency in a control packet relating to route information to suppress the reduction of throughput. <P>SOLUTION: A wireless communication apparatus comprises: a packet transmitting means for periodically transmitting a control packet having a neighboring address list to a peripheral node; a packet receiving means for receiving a control packet transmitted from a peripheral node; a first storage means for storing information on a neighboring node of one hop, which is capable of communication with one hop, upon receipt of the control packet due to the packet receiving means; a second storage means for storing information on a neighboring node of two or more hops, which is capable of communication with two or more hops, based on the neighboring address list of the control packet received by the packet receiving means; and a transmission timing control means in which, based on the information on the neighboring node of one hop and the information on the neighboring node of two or more hops, an installation density of peripheral nodes is estimated and in accordance with the estimated installation density of the peripheral nodes, a transmission timing of the control packet to be transmitted by the packet transmitting means is dynamically changed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a wireless communication device and a wireless communication program, and can be applied to, for example, a wireless communication device and a wireless communication program included in each wireless node that constitutes a multi-hop wireless communication system.

  For example, in a multi-hop wireless network, a network is configured with a plurality of wireless nodes having a packet relay function, and packets are transferred to adjacent wireless nodes by relaying packets between adjacent wireless nodes. Can do.

  In order to relay a packet to a desired wireless node, a routing protocol for determining a wireless node to be transferred next from a destination address is required.

  For example, in the ZigBee Alliance, a cluster tree routing method that eliminates the need for a routing table by devising an address allocation method, an AODV (Ad Hoc On-Demand Distance Vector) method that enables a mesh topology configuration, and multiple nodes Standardization of a routing protocol such as a Many to One system that enables efficient data collection is performed.

  Since the Many to One method is a method that takes into account 1-to-n communication between a sink node and a plurality of nodes, it is expected to be applied to applications such as sensing of environmental information and telemetering.

  FIG. 2 shows the operation of the Many to One routing method. FIG. 2 shows a state in which node a becomes a sink node and sensor data generated in nodes b to j is collected in node a.

  First, each node a to j transmits a packet called a link status command to the neighboring nodes by broadcasting. This command is periodically exchanged between neighboring nodes, for example, every 15 seconds, and each node measures the arrival rate of this packet and the link quality indicator (LQI) to indicate the link cost indicating the link quality between the nodes. Is calculated.

  Next, the sink node transmits a route search packet called an RREQ (Route Request) command. For example, in the case of the AODV method or the like, this RREQ command is used to search for a route from the other party to be transmitted to the transmission source. However, in the Many to One method, the sink is synchronized from all nodes by setting the transmission destination address as a broadcast address. Used to search for a route to a node. The node that has received the RREQ from the sink node performs a relay process for propagating the RREQ command to other nodes. At this time, a metric called path cost is described in RREQ, and the smaller this value is, the lower the arrival cost to the sink node is. When relaying the RREQ, the link cost measured by the link status command is added to the received RREQ path cost and transmitted. By repeating RREQ relay in this way, each node can know the information of the next transfer node for transferring the packet to the sink node. For example, the node having the lowest path cost is selected as the next transfer node. This makes it possible to create an optimum route to the sink node. Through the above operation, an upstream path from each node to the sink node is established (see FIG. 2A).

  Next, each node transmits a packet called a RREC (Route Record) command to the sink node in order to create a downlink route from the sink node. The node that has received the RREC command adds its own address and the number of relays to the RREC command and relays it to the next forwarding node. By repeating this relay, when the RREC command is received by the sink node, it is possible to acquire the address list of the node that has passed from the transmission source node and the number of relays. For example, in FIG. 2, it can be seen that the packet is relayed from the node h to h → d → c → b → a (see FIG. 2B).

  When all nodes transmit the RREC command addressed to the sink node, the sink node can obtain a list of route information to all nodes. When downlink communication is performed from the sink node to each node, the reverse of the order of this address list is written in the header portion of the packet and transferred. The node that has received the packet in which the address list is described relays the packet in accordance with the description in the address list. Through the above operation, a downstream path from the sink node to each node is established (see FIG. 2C).

  This operation is called source routing because it performs path control for uniquely determining the node through which the transmission source node (source node) passes.

ZigBee Specification Revision 17 (ZigBeeDocument 053474r17)

  The link status command in the prior art Many to One method is transmitted based on a predetermined cycle in all nodes, and the number of packets transmitted by the node per unit time is the same. For this reason, when the number of nodes installed increases, the ratio occupied by the packets in the radio band increases, and in places where the node installation density is high, the use efficiency of the radio band is poor due to the influence of the packets transmitted by other nodes. The problem of becoming may arise.

  As a result, in a node installed in a place with a high installation density, the throughput of data communication may be reduced. Therefore, there is a demand for a transmission method of the packet that does not cause unfairness in the use efficiency of the radio band due to the difference in the installation density of the nodes.

  In addition, in the source routing in the prior art Many to One system, an address list indicating route information is described in all downlink packets, so that the overhead of the packet may increase as the number of relay hops increases. In particular, when a wireless communication method such as IEEE 802.15.4 widely used in sensor networks, for example, is used, there is a problem that the throughput of data communication is reduced due to an increase in overhead because the transmission rate is low.

  For this reason, a source routing method in which the overhead amount due to the address list is reduced is desired.

  Therefore, in view of the above problems, the present invention eliminates unfairness in the use efficiency of the radio band due to transmission and reception of control packets that may occur due to the difference in node installation density, reduces the overhead of the address list, and reduces the throughput. A wireless communication device and a wireless communication program for improvement are provided.

  In order to solve such a problem, a wireless communication device according to a first aspect of the present invention is a wireless communication device that performs multi-hop communication. (1) An adjacent address list indicating address information of its own adjacent nodes with respect to peripheral nodes A packet transmission means for periodically transmitting control packets having: (2) a packet reception means for receiving a control packet transmitted by a peripheral node; and (3) one hop based on reception of the control packet by the packet reception means. First storage means for storing communicable 1-hop neighboring node information; and (4) neighboring node information for two or more hops that can be communicated in two or more hops based on a neighboring address list of control packets received by the packet receiving means. Based on the second storage means for storing and (5) 1-hop adjacent node information and 2 or more hops adjacent node information, Analogy to 置密 degree, depending on the installation density of the analogy with the said peripheral node, the packet transmitting means is characterized by comprising a transmission timing control means for dynamically changing the transmission timing of the control packet to be transmitted.

  The wireless communication program according to the second aspect of the present invention periodically transmits a control packet having an adjacent address list indicating address information of its own adjacent node to a peripheral node. (2) Packet receiving means for receiving a control packet transmitted by a peripheral node, (3) Based on reception of the control packet by the packet receiving means, 1-hop neighboring node information communicable in one hop is stored. First storage means, (4) second storage means for storing adjacent node information of two or more hops communicable at two or more hops based on the adjacent address list of the control packet received by the packet receiving means, (5) 1 Based on the adjacent node information of hops and adjacent node information of 2 hops or more, the installation density of the peripheral nodes is estimated, and the estimated peripheral nodes Depending on 置密 degree, packet transmission means, characterized in that the function as the transmission timing control means for dynamically changing the transmission timing of the control packet to be transmitted.

  According to the present invention, it is possible to eliminate unfairness in the use efficiency of a radio band due to transmission / reception of control packets, which may occur due to a difference in installation density of nodes, reduce overhead of an address list, and improve a decrease in throughput.

It is an internal block diagram which shows the internal structure of the radio | wireless node of 1st Embodiment. It is explanatory drawing explaining the conventional Many To One routing system. It is a flowchart which shows the packet transmission / reception process in the radio | wireless node of 1st Embodiment. It is explanatory drawing explaining operation | movement of the radio | wireless node in the network comprised from the some radio | wireless node of 1st Embodiment. It is a figure which shows the control packet transmission amount between the radio | wireless nodes in the network configuration of 1st Embodiment ( _Tunit = 1 second, (alpha) = 0, (beta) = 0). It is a figure which shows the control packet transmission amount between the radio | wireless nodes in the network configuration of 1st Embodiment ( _Tunit = 1 second, (alpha) = 1, (beta) = 0). It is a figure which shows the control packet transmission amount between the radio | wireless nodes in the network configuration of 1st Embodiment ( _Tunit = 1 second, (alpha) = 0, (beta) = 1). It is a figure which shows the control packet transmission amount between the radio | wireless nodes in the network configuration of 1st Embodiment ( _Tunit = 1 second, (alpha) = 1, (beta) = 1). It is an internal block diagram which shows the internal structure of the radio | wireless node of 2nd Embodiment. 6 is a flowchart illustrating RREC command transmission / reception processing in a wireless node according to the second embodiment. It is explanatory drawing explaining operation | movement of the radio | wireless node in the network comprised from the some radio | wireless node of 2nd Embodiment. 10 is a flowchart illustrating SR packet transmission / reception processing in a wireless node according to the second embodiment. It is explanatory drawing explaining operation | movement of the radio | wireless node in the network comprised from the some radio | wireless node of 2nd Embodiment.

(A) First Embodiment Hereinafter, a first embodiment of a wireless communication apparatus and a wireless communication program of the present invention will be described with reference to the drawings.

  In the first embodiment, for example, an embodiment in which the present invention is applied when each wireless node configuring a wireless network (multihop wireless communication system) adopting a multihop communication system relays a control packet is described. Illustrate.

(A-1) Configuration of First Embodiment FIG. 1 is an internal configuration diagram illustrating an internal configuration of a wireless node according to the first embodiment. In FIG. 1, a wireless node 100A according to the first embodiment includes, as a wireless communication device, an antenna 101, an amplifier 102, a wireless transmission / reception unit 103, a packet reception unit 104, a relay processing unit 105, a routing table storage unit 106, and a 2-hop neighbor. The table storage unit 107, the control packet generation unit 108, the transmission timing calculation unit 109, and the packet transmission unit 110 are configured at least.

  The antenna 101 transmits a radio signal from the radio transmission / reception unit 103 or receives a radio signal via the amplifier 102.

  The amplifier 102 receives a radio signal transmitted from the radio transmission / reception unit 103, amplifies the signal strength of the radio wave, and gives the signal to the antenna 101.

  The wireless transmission / reception unit 103 performs mutual conversion between an electrical signal and a wireless signal. The radio transmission / reception unit 103 converts the radio signal received from the antenna 101 into an electric signal, performs modulation processing, etc., and gives a received packet to the packet reception unit 104 or receives a transmission signal received from the packet transmission unit 110 for transmission A radio signal is given to the amplifier 102 by performing demodulation processing, frequency conversion, and the like.

  The packet receiving unit 104 identifies whether the packet is a data packet or a control packet based on the header information of the received packet, and supplies the packet to the relay processing unit 105. Further, when receiving the control packet, the packet receiving unit 104 stores the route information described in the control packet in the routing table storage unit 106. For example, when an RREC command is received as a control packet, the packet receiving unit 104 stores an address list described in the RREC command indicating the address of the relay node up to the packet destination in the routing table 106.

  When the relay processing unit 105 receives a data packet addressed to itself, the relay processing unit 105 performs delivery reception processing to a higher-level processing unit. When the relay processing unit 105 receives a data packet not addressed to itself, the relay processing unit 105 stores the data packet in the routing table storage unit 106. Based on this, in order to relay to the destination of the packet, the relay processing to the next relay destination node is performed. For example, the relay processing unit 105 selects a relay destination node that passes the optimum route based on the path cost to a specific node (for example, a sink node) stored in the routing table storage unit 106.

  Further, when receiving the control packet, the relay processing unit 105 analyzes the internal data and, if necessary, the routing table of the routing table storage unit 106 or the 2-hop adjacency table stored in the 2-hop adjacency table storage unit 107. The content of is updated.

  Here, as the control packet, for example, a command status command, RREQ command, RREC command or the like of the Tony One routing method is applicable. For example, the command status command describes its own adjacent address list, and the link cost indicating the quality of the radio link is described for each adjacent address list. In addition, the RREQ command describes a value such as a path cost for causing a packet to reach a specific node. Further, the RREC command describes an address list indicating the address of the relay node up to the packet destination.

  The relay processing unit 105 updates the address information of the adjacent node capable of one-hop communication stored in the routing table storage unit 106 based on information described in the link status command, for example, or receives the received command status command The 2-hop adjacency table of the 2-hop adjacency table storage unit 107 is updated based on the adjacency address list described in (1).

  The routing table storage unit 106 stores a routing table that is relay route information. The routing table storage unit 106 includes, for example, an address list of adjacent nodes having the control packet transmission source node as an adjacent node, a link cost described for each address list, a path cost to a specific node (for example, a sink node), and the like. Stores the information.

  The two-hop adjacency table storage unit 107 stores a two-hop adjacency table with which it can communicate. The 2-hop adjacency table is a list of addresses of nodes that cannot be directly communicated with each other but can be connected via the 1-hop adjacency node. The 2-hop adjacency table is created by comparing the routing table in the routing table storage unit 106 with the adjoining address list of the received control packet.

  The control packet generator 108 generates a control packet for transmitting a part of the information in the routing table stored in the routing table storage unit 106 to the adjacent node.

  The transmission timing calculation unit 109 transmits the transmission time of the control packet generated by the control packet generation unit 108 by using the rating table stored in the routing table storage unit 106 or the 2-hop adjacency table of the 2-hop adjacency table storage unit 107. Is calculated. Note that the transmission time calculation method of the transmission timing calculation unit 109 will be described in detail in the operation section.

  The packet transmission unit 110 forms data (for example, sensor data) generated by itself, control information generated by the control packet generation unit 108, and a packet relayed from the relay processing unit 105 to another node. Via the wireless network. The packet transmission unit 110 is configured to transmit a control packet when the transmission time calculated by the transmission timing calculation unit 109 is set and the transmission time is reached.

(A-2) Operation of the First Embodiment Next, the operation of processing when relaying in the wireless node 100A of the first embodiment will be described with reference to the drawings.

  FIG. 3 is a flowchart illustrating an operation of packet transmission / reception processing in the wireless node 100A according to the first embodiment.

  FIG. 4A is an explanatory diagram for explaining the operation of a wireless node in a network composed of wireless nodes a to k, for example. Note that in FIG. 4A, a dotted line connecting wireless nodes indicates a wireless link and direct communication is possible.

  First, each of the wireless nodes a to k exchanges control packets with the neighboring nodes, and the packet receiving unit 104 of each of the wireless nodes a to k receives the control packet from the adjacent node (step S301).

  Further, the relay processing unit 105 of each of the wireless nodes a to k updates its own routing table based on the information described in the received control packet (step S302).

  Upon receiving the control packet, each of the wireless nodes a to k can know the transmission source node of the control packet as its adjacent node, and a table of wireless nodes configured by this wireless node group is stored in the routing table storage unit 106. To store. A table composed of the wireless node group is called a 1-hop adjacency table.

  For example, in the case of the wireless node d shown in FIG. 4, since control packets are received from the wireless nodes b, e, f, g, h, these wireless node groups (wireless nodes b, e, f, g, h) are their own. It can be known as an adjacent node. Therefore, the wireless node d stores the 1-hop adjacency table (b, e, f, g, h) in the routing table storage unit 106 as the 1-hop adjacency table. Note that “b” or the like in the 1-hop adjacency table indicates the address of the wireless node b.

  Further, for example, in the case of a link status command, a link cost indicating the quality of the radio link is described for each adjacent address list, and a value such as a path cost to a specific node is described in the RREQ command. The nodes a to k also store this information in the routing table.

  Next, the relay processing unit 105 of each of the wireless nodes a to k compares the 1-hop adjacency table with information described in a control packet (for example, a link status command) received from the adjacent node, and 2-hop adjacency The 2-hop adjacency table in the table storage unit 107 is updated (step S303).

  For example, in the wireless node d, for example, an adjacent address list (a, c, d) is described as an adjacent address list in a control packet (for example, a link status command) received from the wireless node b. The relay processing unit 105 of the wireless node d cannot directly communicate by comparing the 1-hop neighbor table with the neighbor address list of the control packet, but can communicate by two hops via the wireless node b. 2 hop neighboring nodes can be known. This table describing the addresses of the 2-hop adjacent nodes is called a 2-hop adjacent table.

  Specifically, the relay processing unit 105 of the wireless node d has the adjacent address list (a, c, d) described as the adjacent address list in the control packet from the wireless node b, and has deleted its own address. It is determined that (a, c) is a 2-hop adjacent node via the wireless node b. Similarly, using the adjacent address list described in the control packet received from the other adjacent nodes e, f, g, h, the wireless node d obtains its two-hop adjacent table (a, c, i). The data is stored in the 2-hop adjacent table storage unit 107.

  FIG. 4B illustrates a table in which the 1-hop adjacency table and the 2-hop adjacency table held by the wireless nodes a to k are combined (shown as a 1-hop 2-hop adjacency table in FIG. 4B). To do.

  Next, the transmission timing calculation unit 109 of each of the wireless nodes a to k calculates the transmission time of the control packet transmitted by itself using the information in the routing table storage unit 106 and the information in the 2-hop adjacent table storage unit 107. (Step S304).

  Then, in each of the wireless nodes a to k, the control packet generation unit 108 generates a control packet using the information in the routing table storage unit 106 (step S305), the control packet transmission time is set (step S306), and the transmission is performed. When it is time (step S307), the packet transmitter 110 transmits a control packet (step S308).

  Here, the transmission timing calculation unit 109 estimates the installation density of wireless nodes located in the vicinity of itself, and calculates the transmission time according to the estimated installation density of the peripheral nodes. The installation density of the peripheral nodes refers to the number of wireless nodes that can communicate in a predetermined hop (for example, 1 hop, 2 hop, etc.) range.

  The transmission timing calculation unit 109 calculates the transmission time so that the transmission interval of the control packet is increased when the setting density of the peripheral node is large, and the transmission interval of the control packet is decreased when the installation density of the peripheral node is small. Calculate the transmission time. Here, for example, whether or not the installation density of the peripheral nodes is high can be determined by setting one or a plurality of threshold values. The threshold value can be appropriately determined according to the operation of the network.

Also, the transmission time T _send calculated by the transmission timing calculation unit 109 is determined by, for example, Expression (1).

T _send = T _unit × ( _αN 1 _hop + βN 2 _hop +1) (1)
_{Here, T Unit} is a time _{unit, N 1hop} one hop neighbor _{number, N 2hop} indicates two hops adjacent nodes, alpha, beta denotes a coefficient. For example, T _unit is a minimum unit time for transmitting a control packet, and a value such as 1 second is set.

  Formula (1) exemplifies a case where the transmission time is calculated in consideration of the installation density in the case of the 1-hop range and the case of 2 hops. In Expression (1), if the value of α is increased, the effect of the number of adjacent one-hop nodes becomes significant, and if the value of β is increased, the effect of the number of adjacent 2-hop nodes becomes significant.

For example, in this case, the transmission timing calculation unit 109 refers to the 1-hop adjacent table of the routing table storage unit 106 and increases the value of α and increases the transmission time T _send as the number of 1-hop adjacent nodes increases. To be. Also, the transmission timing calculation unit 109 refers to the 2-hop adjacency table in the 2-hop adjacency table storage unit 107 and increases the value of β and increases the transmission time T _send as the number of 2-hop adjacent nodes increases. Like that. That is, the transmission timing calculation unit 109 determines the 1-hop adjacency table and the 2-hop adjacency table separately, and calculates the transmission time of the control packet.

  Note that the method for determining the values of α and β takes larger values as the number of adjacent nodes increases. For example, the values of α and β may be determined in advance according to the network configuration. Further, for example, the values of α and β may be variably determined according to a change in the number of adjacent nodes. For example, when the number of adjacent nodes is “1”, the values of α and β are “0”, and when the number of adjacent nodes is “2 to 3”, the values of α and β are “1”, etc. As described above, a method of determining the values of α and β according to the number of adjacent nodes can be applied. Alternatively, the values of α and β may be obtained using a predetermined relational expression for calculating α and β according to the number of adjacent nodes.

Furthermore, the transmission timing calculation unit 109, all of the wireless nodes constituting the network may determine the same transmission time T _{the send,} each of which can determine the transmission time T _{the send} to each wireless node. When each wireless node obtains the transmission time T _send individually, the transmission timing calculation unit 109 describes the calculated transmission time T _send in a control packet and informs other wireless nodes of its own transmission time T _send. . The transmission timing calculation unit 109 may describe parameters (for example, α and β) that determine the transmission time T _send in a control packet and transmit the parameters to other wireless nodes.

The transmission timing calculation unit 109 refers to the transmission time T _{the send} to each adjacent node is calculated as described in the control packet, it may be calculated transmission time T _{the send} its own. For example, the transmission time T _send of each 1-hop neighboring node included in the control packet is stored in the routing table storage unit 106. The transmission timing calculation unit 109 reads the transmission time T _send of each 1-hop adjacent node from the routing table storage unit 106. At this time, when the transmission time T _send of the one-hop adjacent node is short, a method of calculating so that the transmission time T _{send of} itself is increased can be applied. This means that if the transmission time of a 1-hop adjacent node is short, it means that the number of control packets received by itself increases, so increasing the transmission time of itself reduces the number of control packets transmitted and received. can do.

FIG. 5 shows the amount of control packet transmission between wireless nodes when, for example, T _unit = 1 second, α = 0, and β = 0 are substituted into equation (1). That is, the case where the transmission time T _send of the control packet of each of the wireless nodes a to k is 1 second is illustrated.

  FIG. 5B is an explanatory diagram illustrating the number of control packets transmitted by the wireless node per minute in a table format. For example, the wireless node d indicates that 60 control packets are transmitted per minute to each of the wireless nodes b, e, f, g, and h.

  FIG. 5A is an explanatory diagram showing the number of control packets exchanged per minute between wireless nodes. For example, a broken line between the wireless node b and the wireless node d indicates a wireless link, and the number “120” written near the broken line indicates the number of packets exchanged between the wireless node b and the wireless node (that is, , The sum of the number of control packets “60” from the wireless node b to the wireless node d + the number of control packets “60” from the wireless node d to the wireless node b).

  FIG. 5C is an explanatory diagram showing the number of control packets transmitted / received per minute by each of the wireless nodes a to k. For example, the wireless node d indicates that “600” control packets are transmitted and received in 1 minute between the adjacent nodes b, e, f, g, and h.

In the case of the parameter set illustrated in FIG. 5, the transmission times T _send of the wireless nodes a to k are relatively short, and the number of control packets transmitted per unit time of the wireless nodes a to k is the same. For example, since the wireless node d receives a large amount of control packets, the data communication throughput may be reduced.

  Therefore, in the first embodiment, based on the 1-hop adjacency table and the 2-hop adjacency table, the installation density of peripheral nodes that are considered to exist in the vicinity is calculated, and a radio node with a high installation density transmits a control packet. Set a longer interval.

6 to 8 are explanatory diagrams for explaining how the number of control packets between the wireless nodes a to k is reduced by changing the value of α and the value of β in the equation (1). FIG. 6 shows a case where, for example, T _unit = 1 second, α = 1, β = 0, and FIG. 7 shows a case where, for example, T _unit = 1 second, α = 0, β = 1. FIG. 8 shows a case where, for example, T _unit = 1 second, α = 1, and β = 1.

  6 to 8, for example, the number of packets transmitted / received per minute by the wireless node d is “175” in the case of FIG. 6, “131” in the case of FIG. 7, and “ 73 ”, which indicates that the number of transmission / reception of control packets is reduced compared to the case of FIG. 5 in which α = 0 and β = 0.

  In addition, in the explanatory diagrams of FIGS. 5 to 8, control packet teachings are transmitted and received in the vicinity of the wireless node d having a relatively high installation density as compared to the vicinity of the wireless node i and the wireless node k having a relatively low installation density. It can be seen that is decreasing. As a result, the ratio of the control packet occupying the wireless band of the wireless node d having a high installation density decreases, and the throughput of data communication can be ensured.

From the above operation, the wireless node does not transmit the control packet immediately after generating it, but maintains the control packet until the calculated transmission time T _send, thereby adjusting the transmission timing of the control packet in consideration of the number of neighboring nodes. It becomes possible.

(A-3) Effects of First Embodiment As described above, according to the first embodiment, it is possible to dynamically control the transmission timing of control packets according to the installation density of wireless nodes. . Further, according to the first embodiment, this transmission timing control can eliminate unfairness due to a difference in node installation density, and secures a wireless band for data communication even in a wireless node with a high installation density. can do.

(B) Second Embodiment Next, a second embodiment of the wireless communication apparatus and the wireless communication program of the present invention will be described with reference to the drawings.

(B-1) Configuration of Second Embodiment FIG. 9 is an internal configuration diagram illustrating an internal configuration of a wireless node according to the second embodiment. In FIG. 9, the wireless node 100B according to the second embodiment includes, as a wireless communication device, an antenna 101, an amplifier 102, a wireless transmission / reception unit 103, a packet reception unit 104, a relay processing unit 201, a routing table storage unit 106, and a 2-hop neighbor. The table storage unit 107, the control packet generation unit 108, the transmission timing calculation unit 109, the packet transmission unit 110, and the next forwarding node determination unit 202 are configured at least.

  The second embodiment is different from the first embodiment in that a relay processing unit 201 is provided instead of the relay processing unit 105, and a next forwarding node determination unit 202 is newly provided.

  When the relay processing unit 201 receives an RREC command that is a control packet in addition to the processing described in the first embodiment, the transmission source address of the RREC command is described in the address list described in the RREC command. If the source address of the RREC command is described, do not add its own address to the address list. If not, add its own address to the address list. It is something to add.

  Further, the relay processing unit 201 can apply another method. For example, the relay processing unit 201 refers to TTL (Time To Live) described in the RREC command. For example, when the TTL value is an odd number, the relay processing unit 201 adds its own address to the address list, and the TTL value is an even number. In the case of, please do not append.

  The next forwarding node determination unit 202 includes the header information of the source routing packet (SR packet) transferred from another wireless node, the information of the routing table storage unit 106, and the 2-hop adjacency table of the 2-hop adjacency table storage unit 107. The wireless node to be transferred next is determined based on the above information.

(B-2) Operation of Second Embodiment Next, an operation of packet transmission / reception processing of the wireless node 100B of the second embodiment will be described with reference to the drawings.

  FIG. 10 is a flowchart illustrating the operation of the RREC command transmission / reception process in the wireless node 100B according to the second embodiment.

  FIG. 11 is an explanatory diagram for explaining a state in which an RREC command is transmitted / received in a network including wireless nodes a to l. In FIG. 11A, a case where an RREC command is transmitted from the wireless node 1 (l is a lowercase letter L) to the wireless node a is illustrated, and a thick line indicates a transmission path of the RREC command, and is described near the thick line. For example, a number such as (1) indicates the relay order of the RREC command.

  First, the wireless node 1 transmits an RREC command whose destination is the wireless node a, and the wireless node k that is an adjacent node of the wireless node 1 receives the RREC command (step S1001).

  Conventionally, the wireless node that has received the RREC command adds its own address to the address list described in the RREC command and relays it to the next forwarding node.

  In contrast, in the second embodiment, the relay processing unit 201 of the wireless node that has received the RREC command refers to the address list (step S1002), and the address of the transmission source node of the RREC command is described in the address list. It is determined whether or not it has been performed (step S1003).

  Then, when the address of the transmission source node is not described in the address list, the relay processing unit 201 adds the own address to the address list and transmits the RREC packet (steps S1004 and S1005), and the transmission source address is the address. When it is described in the list, the RREC packet is transmitted to the next forwarding node without describing its own address in the address list (step S1005).

  For example, in the case of the example of FIG. 11, the wireless node k that has received the RREC command from the wireless node l has its own address “k” because the address “l” of the wireless node 1 is described in the address list. The data is transferred to the wireless node i, which is the next transfer node, without additional writing ((2) in FIG. 11A).

  In addition, since the wireless node i that has received the RREC command from the wireless node k does not include the address “k” of the wireless node k in the address list, the wireless node i adds its own address “i” to the address list, and The data is transferred to the wireless node h which is a transfer node ((3) in FIG. 11A).

  By performing such an operation, as shown in FIG. 11B, the field size of the address information described in the address list of the RREC command can be halved compared to the conventional case. As a result, overhead can be reduced, and a reduction in throughput can be avoided.

  Next, a case where source routing is performed from the wireless node a to the wireless node 1 based on the path information obtained by the RREC command will be described with reference to the drawings.

  FIG. 12 is a flowchart showing the operation of the source routing process in the wireless node 100B.

  FIG. 13 is an explanatory diagram for explaining source routing processing in a network composed of wireless nodes a to l. In FIG. 13A, the thick line is the relay route of the source routing packet (SR packet), and the numbers such as (1) shown near the thick line indicate the relay order.

  In the following, a case where the wireless node d receives an SR packet will be described as an example.

  First, the wireless node a describes the address list obtained as shown in FIGS. 10 and 11 and transmits an SR packet whose destination is the wireless node l. The SR packet is transmitted to the wireless node d via the wireless node b.

  When the wireless node d receives the SR packet from the wireless node b (step S1006), the wireless node d refers to the address list described in the SR packet (step S10007).

  In the case of the prior art, the relay order of the wireless nodes that relay the SR packet is described in the address list, so the next address in which its own address is described is used as the next transfer address. For example, in the conventional case, if the address list is “l, k, i, h, b, d”, the wireless nodes b → d → h → i → k → l are relayed in order from the end. The address list held by the wireless node is reversed in order to obtain an address list “d, b, h, i, k, h”, and the wireless node b → d → h → i → k → l. You may make it relay.

  On the other hand, in the second embodiment, since the address list is collected by the RREC command as described in FIGS. 10 and 11, the address of the next forwarding node is not always described. .

  Therefore, the next forwarding node determination unit 202 refers to the 1-hop adjacency table stored in its own routing table storage unit 106 (step S1008), and the address described in the address list is entered in the 1-hop adjacency table. It is determined whether or not there is (step S1009).

  If the entry is not entered, the next forwarding node determination unit 202 refers to the two-hop adjacency table in the two-hop adjacency table storage unit 107 (step S1010), determines the next forwarding node (step S1011), and The transmission unit 110 transmits the SR packet to the next transfer node (step S1012).

  On the other hand, the next forwarding node determination unit 202 determines the next forwarding node using the routing table of the routing table storage unit 106 when the entry is made (step S1011), and the packet transmission unit 110 sends the SR packet to the next forwarding node. The transmission is performed (step S1012).

  In the example of FIG. 13, the address list of the SR packet transmitted by the wireless node a is “l, i, d”. Further, the 1-hop adjacency table of the wireless node d is “b, e, f, g, h” as shown in FIG.

  The next forwarding node determination unit 202 of the wireless node d that has received the SR packet from the wireless node b refers to the SR packet even when referring to the 1-hop adjacency table “b, e, f, g, h” of the routing table storage unit 106. The address “l, i” described in the address list is not entered.

  Therefore, the next forwarding node determination unit 202 can know that the address “i” described in the address list of the SR packet is entered by referring to the 2-hop adjacency table “a, c, i”. In order to reach the wireless node i using the 1-hop adjacent table and the 2-hop adjacent table, the next forwarding node is determined as the wireless node h. Thereby, the wireless node d transmits the SR packet with the next forwarding node as the wireless node h ((3) in FIG. 13A).

  Next, the wireless node h receives the SR packet transmitted by the wireless node d. When the next forwarding node determination unit 202 of the wireless node h refers to the 1-hop adjacency table “d, i” of the routing table storage unit 106, it is confirmed that the address “i” described in the address list of the SR packet has been entered. Therefore, the SR packet is transmitted with the next forwarding node as the wireless node i ((4) in FIG. 13A).

  Even in a state where the information in the address list is halved by the above operation, the packet can be relayed to the target node by referring to the 1-hop adjacency table and the 2-hop adjacency table.

  As another embodiment, the relay processing unit 201 may use the TTL of the received RREC packet to determine whether to add to the address list to the RREC packet. Since the TTL is subtracted for each relay hop, for example, when the TTL value is an odd number, additional writing to the address list is performed, and when the TTL value is even, no additional recording is performed to the address list.

  In addition, by describing the 2-hop adjacency table in the control packet, the adjacent node can acquire information on neighboring nodes that are 3 hops away. For this reason, even if the address is added to the RREC once every three nodes, it is possible to relay the packet to the target node by searching the 3-hop adjacency table.

(B-3) Effect of Second Embodiment As described above, according to the second embodiment, the information amount of the RREC packet can be halved, and the overhead amount of the control packet can be reduced. . In addition, since the amount of overhead at the time of source routing can be reduced, the payload length per packet becomes longer, and the throughput can be improved.

(C) Other Embodiments In the present invention, for the purpose of making control information equal to or less than a certain percentage of the usable radio band, the transmission period of a link status command (control packet) is set according to the installation density of nodes. A means for dynamically changing and a means for reducing the size of the address list described in the packet are provided by using the information of the two-hop neighboring node obtained by exchanging the control packet.

  In the first and second embodiments described above, the hardware configuration of the wireless communication device of the wireless node can be applied to an existing hardware configuration, and includes, for example, a CPU, a RAM, a ROM, an EEPROM, and the like. In addition, for example, the CPU realizes the functions described in the first and second embodiments by software processing that realizes a processing program stored in the ROM.

100A and 100B ... wireless node, 101 ... antenna, 102 ... amplifier,
103 ... wireless transmission / reception unit, 104 ... packet reception unit, 105, 201 ... relay processing unit,
106: Routing table storage unit, 107: 2-hop adjacent table storage unit,
108 ... control packet generator, 109 ... transmission timing calculator,
110: Packet transmission unit, 202: Next forwarding node determination unit.

Claims (12)

In a wireless communication device that performs multi-hop communication,
Packet transmitting means for periodically transmitting a control packet having an adjacent address list indicating address information of its adjacent nodes to the peripheral nodes;
A packet receiving means for receiving the control packet transmitted by the peripheral node;
First storage means for storing 1-hop neighboring node information communicable in 1 hop based on reception of the control packet by the packet receiving means;
Based on the adjacent address list of the control packet received by the packet receiving means, second storage means for storing adjacent node information of two or more hops capable of communicating in two or more hops;
Based on the 1-hop adjacent node information and the 2-hop or more adjacent node information, the installation density of the peripheral nodes is estimated, and the control packet transmitted by the packet transmission unit is transmitted according to the estimated installation density of the peripheral nodes. A wireless communication apparatus comprising: a transmission timing control unit that dynamically changes timing.   2. The radio communication apparatus according to claim 1, wherein the transmission timing control means changes the transmission interval of the control packet to be increased as the installation density of the peripheral nodes is increased.   3. The radio according to claim 1, wherein the transmission timing control unit changes the transmission interval of the control packet to be larger as the number of one-hop neighboring nodes is larger from the one-hop neighboring node information. Communication device.   4. The transmission timing control unit according to any one of claims 1 to 3, wherein the transmission interval of the control packet is increased as the number of adjacent nodes of 2 hops or more increases from the 2 hops or more adjacent node information. A wireless communication device according to claim 1.   5. The wireless communication apparatus according to claim 3, wherein the transmission timing control unit calculates an installation density of the peripheral nodes from the number of adjacent nodes of 1 hop and the number of adjacent nodes of 2 hops or more.   The wireless communication according to any one of claims 1 to 5, wherein the transmission timing control means describes the transmission timing of the control packet calculated by itself and transmits the control packet to the packet transmission means. apparatus. When the packet receiving unit receives a route collection packet for collecting a relay route by adding its own address information to the route information, the relay node refers to the route information described in the route collection packet, and Relay processing means for intermittently adding address information;
When the packet receiving means receives the packet having the route information obtained by the route collection packet, the next transfer destination of the packet is determined using the one-hop neighboring node information and the two or more hops neighboring node information. The wireless communication apparatus according to claim 1, further comprising: a next transfer destination determination unit that performs the following.   Whether the relay processing unit adds its own address information according to whether or not the address information of the transmission source node of the route collection packet is described in the route information of the route collection packet. The wireless communication apparatus according to claim 7, wherein the determination is made.   8. The wireless communication apparatus according to claim 7, wherein the relay processing unit determines whether or not to add its own address information by referring to the number of remaining relays of the route collection packet.   The next transfer destination determination unit detects a 2-hop transfer destination from the adjacent node information of two or more hops when the route information of the packet received by the packet reception unit does not include a one-hop adjacent node, The wireless communication apparatus according to any one of claims 7 to 9, wherein the next transfer destination is a 1-hop adjacent node that reaches the 2-hop transfer destination.   11. The packet transmission means transmits 2-hop adjacent node information in the control packet and transmits the control packet, and the second storage means stores 3-hop adjacent node information. A wireless communication device according to claim 1. A packet transmission means for periodically transmitting a control packet having a neighboring address list indicating address information of its neighboring nodes to a peripheral node of a wireless communication device performing multi-hop communications;
A packet receiving means for receiving the control packet transmitted by the peripheral node;
First storage means for storing 1-hop neighboring node information communicable in 1 hop based on reception of the control packet by the packet receiving means;
Second storage means for storing adjacent node information of two or more hops communicable in two or more hops based on the adjacent address list of the control packet received by the packet receiving means;
Based on the 1-hop adjacent node information and the 2-hop or more adjacent node information, the installation density of the peripheral nodes is estimated, and the control packet transmitted by the packet transmission unit is transmitted according to the estimated installation density of the peripheral nodes. A wireless communication program that functions as transmission timing control means for dynamically changing timing.

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