JP2009130517A - Radio device and radio network equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio device which can stabilize a radio network. <P>SOLUTION: A transmission rate decision means 160 decides a transmission rate based on a data attainment condition, and outputs to a metric decision means 201. The metric decision means 201 decides a metric of a radio link between adjacent radio devices based on the transmission rate and a packet loss ratio. A smoothing means 202 smoothes the metric decided by the metric decision means 201, and outputs it to an updating means 241 and a message creation means 242. The updating means 241 updates a routing table 21 by the metric from the smoothing means 202. The message creation means 242 broadcasts the metric from the smoothing means 202. A route search means 203 searches routes referring the updated routing table 21, and a communication means 204 transmits packets according to the searched route. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a wireless device and a wireless network including the wireless device, and more particularly, to a wireless device used for a wireless network constructed autonomously and a wireless network including the wireless device.

  An ad hoc network is a network that is autonomously and instantaneously constructed by a plurality of wireless devices communicating with each other. In an ad hoc network, when two wireless devices that communicate with each other do not exist in the communication area, a wireless device located between the two wireless devices functions as a router and relays a data packet. Can be formed.

  Dynamic routing protocols that support multi-hop communication include table-driven protocols and on-demand protocols. The table-driven protocol periodically exchanges control information related to a route and constructs a route table in advance, and includes FSR (Fish-eye State Routing), OLSR (Optimized Link State Routing), and TBRPF (Topology). (Dissociation Based on Reverse-Path Forwarding) and the like are known.

  In addition, the on-demand protocol is a method for constructing a route to a destination for the first time when a data transmission request occurs, and includes DSR (Dynamic Source Routing) and AODV (Ad Hoc On-Demand Distance Vector Routing). Are known.

In a conventional ad hoc network, a metric that determines the topology of a wireless network is determined by communication quality such as a transmission rate and a packet loss rate (Non-Patent Documents 1 and 2).
Y. Yang, J. Wang, and R. Kravets, “Designing routing metrics for mesh networks,” Proc. WiMesh'05, 2005. “Joint SEE-Mesh / Wi-Mesh Proposal to 802.11 TGs”, IEEE802.11-06 / 0328r0.

  However, the wireless system represented by IEEE 802.11 supports multi-rate transmission, the transmission rate dynamically changes according to the rate control algorithm, and the communication quality of the wireless link depends on the wireless communication environment. It changes every moment.

  If the wireless routing protocol is configured to advertise in the wireless network a metric that immediately reflects these changing parameters, the wireless communication path is not stable, and as a result, good wireless communication cannot be performed. There is. That is, there is a problem that the wireless network becomes unstable due to dynamic fluctuation of the metric.

  Further, when the metric dynamically changes, there is a problem that it is difficult to advertise the metric without any contradiction between wireless devices forming the wireless link. Furthermore, when the metric dynamically changes, there is a problem that a time difference for transmitting information between wireless devices forming a wireless link occurs, and it is difficult to share the metric without contradiction.

  Further, since the packet loss rate varies depending on the transmission rate, the metric changes depending on which rate is adopted as a result of rate control. That is, in the radio link A-B configured by the radio device A and the radio device B, the transmission rate in the A → B direction and the transmission rate in the B → A direction are not necessarily the same rate. The packet loss rate is also different between the A → B direction and the B → A direction.

  Therefore, when the transmission rate and the packet loss rate change dynamically, there is a problem that it is difficult to uniquely determine a metric between adjacent wireless devices.

  More specifically, in a hop-by-hop proactive routing protocol such as OLSR, the Dijkstra method or the like is used as an algorithm for obtaining the shortest path length in order to search for the shortest path from the wireless device.

  Furthermore, in the hop-by-hop routing protocol, if the metric, which is the weight of the route, does not satisfy the isotonicity (Isotonity), the route for transmitting the packet becomes loop-free, and the optimum solution of the route is guaranteed. It is pointed out that this is not done (Non-Patent Document 2).

  From the viewpoints of calculation amount, memory reduction, and traffic reduction, it is preferable to search for the shortest path not with an effective graph having directionality but with an undirected graph not aware of directionality.

  However, the RA-OLSR Hello message and TC (Topology Control) message described in Non-Patent Document 2 can advertise only one metric for one radio link, and are directed (bidirectional) information. Cannot be advertised.

  Because of these restrictions, isolating the communication quality evaluated in one of the two directions as a metric and configuring the routing protocol to determine the shortest path length of the undirected graph satisfies the isotonicity. However, there is a problem that a radio link loop occurs.

  Furthermore, OLSR uses a unique mechanism called MPR (Multi Point Relay) to improve the efficiency of flooding, and link information corresponding to two or more hops is advertised as a topology set from wireless devices that have become MPRs. .

  However, the MPR decision algorithm includes the assumption that the link metric is symmetric, and if there is a wireless link with an asymmetric metric, the MPR is not guaranteed to be optimal, and the MPR The metric advertised by the wireless device is not necessarily the best metric.

  As a result, there is a problem that isotonicity is not guaranteed, loop-freeness, and selection of a path with the lowest cost cannot be guaranteed.

  As described above, the conventional ad hoc network has a problem that the wireless network becomes unstable due to various problems described above.

  Therefore, the present invention has been made to solve such a problem, and an object thereof is to provide a wireless device capable of stabilizing a wireless network.

  Another object of the present invention is to provide a wireless network including a wireless device capable of stabilizing the wireless network.

  According to the present invention, the wireless device includes smoothing means, communication means, and route search means. The smoothing means smoothes a metric indicating a route evaluation of a wireless link formed between the wireless device and an adjacent wireless device adjacent to the wireless device. The communication means advertises the metric smoothed by the smoothing means. The route search means searches for a route to the transmission destination using the smoothed metric.

  Preferably, the smoothing means smoothes the metric by calculating an average of n (n is an integer of 2 or more) actually measured metrics.

  Preferably, the smoothing means smoothes the metric so that the change width of the metric is equal to or less than a threshold value.

  Preferably, the wireless device further includes a determination unit. The determining means includes a first metric in the first wireless link when transmitting a packet from the wireless device to the adjacent wireless device, and a second metric in transmitting a packet from the adjacent wireless device to the wireless device. Based on the second metric, a bi-directional metric in the radio link between the radio device and the adjacent radio device is determined. The smoothing means smoothes the bidirectional metric determined by the determining means.

  Preferably, the determining unit includes a communication quality determining unit and a metric determining unit. The communication quality determining means determines the communication quality in the first radio link. The metric determining means determines the first metric according to the communication quality determined by the communication quality determining means, and both based on the determined first metric and the second metric transmitted from the adjacent wireless device. Determine the direction metric.

  Preferably, the wireless device further includes transmission timing adjustment means. The transmission timing adjusting unit performs the first control so that the transmission interval of the first control packet including the bidirectional metric determined by the determining unit is equal to or longer than the transmission period of the second control packet used for exchanging the path information. Adjust the transmission timing for advertising the packet. The communication unit advertises the bidirectional metric at the transmission timing adjusted by the transmission timing adjustment unit.

  Preferably, the transmission timing adjusting means adjusts the transmission timing to a timing at which the bi-directional metric fluctuation is equal to or less than a threshold value.

  Preferably, the wireless device further includes update timing synchronization means and update means. The update timing synchronization means synchronizes the update timings for updating the routing table for determining the route to the transmission destination with a bidirectional metric between a plurality of wireless devices. The update means updates the routing table using the bidirectional metric at the update timing synchronized by the update timing synchronization means. Then, the route search means determines a route to the transmission destination using the routing table updated by the update means.

  According to the present invention, the wireless device includes a determination unit, a transmission timing adjustment unit, a communication unit, and a route search unit. The determining unit determines a metric indicating route evaluation of a radio link formed between the radio device and an adjacent radio device adjacent to the radio device. The transmission timing adjusting unit performs the first control so that the transmission interval of the first control packet including the bidirectional metric determined by the determining unit is equal to or longer than the transmission period of the second control packet used for exchanging the path information. Adjust the transmission timing for advertising the packet. The communication unit advertises the metric at the transmission timing adjusted by the transmission timing adjustment unit. The route search means searches for a route to the transmission destination using the metric.

  Preferably, the transmission timing adjusting means adjusts the transmission timing to a timing at which the metric variation is equal to or less than a threshold value.

  Preferably, the determining unit includes a first metric in the first radio link when transmitting a packet from the wireless device to the adjacent wireless device, and a second metric when transmitting the packet from the adjacent wireless device to the wireless device. Based on the second metric in the wireless link, a bidirectional metric in the wireless link between the wireless device and the adjacent wireless device is determined. The communication unit advertises the bidirectional metric at the transmission timing adjusted by the transmission timing adjustment unit. The route search means searches for a route to the transmission destination using a bidirectional metric.

  Preferably, the determining unit includes a communication quality determining unit and a metric determining unit. The communication quality determining means determines the communication quality in the first radio link. The metric determining means determines the first metric according to the communication quality determined by the communication quality determining means, and both based on the determined first metric and the second metric transmitted from the adjacent wireless device. Determine the direction metric.

  Preferably, the wireless device further includes smoothing means. The smoothing means smoothes the bidirectional metric. The communication unit advertises the bidirectional metric smoothed by the smoothing unit at the transmission timing. The route search means searches for a route to the transmission destination using the smoothed bidirectional metric.

  Preferably, the wireless device further includes update timing synchronization means and update means. The update timing synchronization means synchronizes the update timings for updating the routing table for determining the route to the transmission destination according to the bidirectional metric determined by the determination means, among the plurality of wireless devices. The update means updates the routing table using the bidirectional metric at the update timing synchronized by the update timing synchronization means. Then, the route search means searches for a route to the transmission destination using the routing table updated by the update means.

  Further, according to the present invention, the wireless device includes a determination unit, an update timing synchronization unit, an update unit, and a route search unit. The determining unit determines a metric indicating route evaluation of a radio link formed between the radio device and an adjacent radio device adjacent to the radio device. The update timing synchronization means synchronizes the update timings for updating the routing table for determining the route to the transmission destination according to the metric determined by the determination means, among the plurality of wireless devices. The update means updates the routing table with the metric determined by the determination means at the update timing synchronized by the update timing synchronization means. The route search means searches for a route to the transmission destination using the routing table updated by the update means.

  Preferably, the wireless device further includes a transmission timing adjusting unit and a communication unit. The transmission timing adjusting unit performs the first control so that the transmission interval of the first control packet including the bidirectional metric determined by the determining unit is equal to or longer than the transmission period of the second control packet used for exchanging the path information. Adjust the transmission timing for advertising the packet. The communication unit advertises the metric at the transmission timing adjusted by the transmission timing adjustment unit.

  Preferably, the determining unit includes a first metric in the first radio link when transmitting a packet from the wireless device to the adjacent wireless device, and a second metric when transmitting the packet from the adjacent wireless device to the wireless device. Based on the second metric in the wireless link, a bidirectional metric in the wireless link between the wireless device and the adjacent wireless device is determined. The update means updates the routing table with the bidirectional metric determined by the determination means at the update timing synchronized by the update timing synchronization means.

  Preferably, the determining unit includes a communication quality determining unit and a metric determining unit. The communication quality determining means determines the communication quality in the first radio link. The metric determining means determines the first metric according to the communication quality determined by the communication quality determining means, and both based on the determined first metric and the second metric transmitted from the adjacent wireless device. Determine the direction metric.

  Preferably, the wireless device further includes smoothing means. The smoothing means smoothes the bidirectional metric. The communication unit advertises the bidirectional metric smoothed by the smoothing unit at the transmission timing adjusted by the transmission timing adjusting unit. The updating unit updates the routing table using the bidirectional metric smoothed by the smoothing unit.

  Furthermore, according to the present invention, the wireless network is a wireless network including the wireless device according to any one of claims 1 to 19.

  In the present invention, the metric variation indicating the path evaluation of the wireless link formed between two adjacent wireless devices is reduced, and the metric with the reduced variation is advertised within the wireless network, and the variation A route to the transmission destination is searched based on the metric with a reduced width. As a result, the fluctuation range of the metric of the wireless link formed between two adjacent wireless devices in the entire wireless network is reduced, and the number of times of path switching is reduced.

  Therefore, according to the present invention, the wireless network can be stabilized.

  In the present invention, the update period of the metric value stored when transmitting a message including route information is set to be equal to or longer than the period of transmitting the message. As a result, the number of metric updates in the wireless network decreases, the number of updates of the routing table 21 also decreases, and path switching also decreases.

  Therefore, according to the present invention, the wireless network can be stabilized.

  Furthermore, in the present invention, the update timing of the routing table created using the metric indicating the route evaluation of the radio link formed between two adjacent radio devices is synchronized between the plurality of radio devices, and the synchronization is performed. The route to the transmission destination is searched using the updated routing table. As a result, isotonicity is guaranteed, the route for transmitting the packet to the transmission destination becomes loop-free, and the optimum route to the transmission destination is guaranteed.

  Therefore, according to the present invention, the wireless network can be stabilized.

  Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

    FIG. 1 is a schematic diagram of a wireless network including a wireless device according to an embodiment of the present invention. The wireless network 100 includes wireless devices 31 to 43. The wireless devices 31 to 43 are arranged in a wireless communication space and autonomously configure a wireless network. The antennas 51 to 63 are attached to the wireless devices 31 to 43, respectively.

  For example, when transmitting data from the wireless device 31 to the wireless device 42, the wireless devices 32 and 35 to 41 relay the data from the wireless device 31 and deliver the data to the wireless device 42.

  In this case, the wireless device 31 can perform wireless communication with the wireless device 42 via various routes. That is, the wireless device 31 can perform wireless communication with the wireless device 42 via the wireless devices 37 and 41, and perform wireless communication with the wireless device 42 via the wireless devices 32, 36, and 39. It is also possible to perform wireless communication with the wireless device 42 via the wireless devices 32, 35, 38, and 40.

  When wireless communication is performed via the wireless devices 37 and 41, the number of hops is the smallest “3”, and when wireless communication is performed via the wireless devices 32, 36, and 39, the number of hops is “4”. When wireless communication is performed via the devices 32, 35, 38, and 40, the number of hops is the largest, “5”.

  Accordingly, when a route for performing wireless communication through the wireless devices 37 and 41 is selected, the number of hops becomes the smallest “3”, so that the wireless device 31 has the smallest number of hops, that is, wireless device 31-wireless device 37-wireless. Multi-hop wireless communication is performed with the wireless device 42 via a route including the device 41 and the wireless device 42.

  However, when performing such multi-hop wireless communication, a metric indicating a route evaluation of a wireless link formed between two adjacent wireless devices dynamically changes due to a change in the wireless communication environment or the like. The stability of multi-hop wireless communication is reduced.

  Accordingly, a method for performing stable multi-hop wireless communication using the established wireless communication path when the wireless communication path is autonomously established in the wireless network 100 will be described below.

  In the following, the OLSR protocol is used as a protocol for establishing a wireless communication path between a transmission source and a transmission destination. The OLSR protocol is a table-driven routing protocol, and exchanges route information using a Hello message and a TC message to create a routing table.

[Embodiment 1]
FIG. 2 is a schematic block diagram showing the configuration of the wireless device 31 shown in FIG. 1 in the first embodiment. The wireless device 31 includes an antenna 11, an input unit 12, an output unit 13, a user application 14, and a communication control unit 15.

  The antenna 11 constitutes each of the antennas 51 to 63 shown in FIG. The antenna 11 receives data from other wireless devices via the wireless communication space, outputs the received data to the communication control unit 15, and transmits the data from the communication control unit 15 via the wireless communication space. Send to other wireless device.

  The input unit 12 accepts a message and data destination input by the operator of the wireless device 1 and outputs the accepted message and destination to the user application 14. The output unit 13 displays a message according to control from the user application 14.

  The user application 14 generates data based on the message and destination from the input unit 12 and outputs the data to the communication control unit 15.

  The communication control unit 15 includes a plurality of modules that perform communication control in accordance with an ARPA (Advanced Research Projects Agency) Internet hierarchical structure. That is, the communication control unit 15 includes a radio interface module 16, a MAC (Media Access Control) module 17, a buffer 18, an LLC (Logical Link Control) module 19, an IP (Internet Protocol) module 20, and a routing table 21. And a TCP module 22, a UDP module 23, and a routing daemon 24.

  The wireless interface module 16 belongs to the physical layer, modulates / demodulates a transmission signal or a reception signal according to a predetermined rule, and transmits / receives a signal via the antenna 11. The wireless interface module 16 detects the received signal strength RSSI of the Hello packet received by the antenna 11 from another wireless device, and outputs the detected received signal strength RSSI to the routing daemon 24.

  The wireless interface module 16 receives topology information TPIF indicating the topology of the entire wireless network 100 from the routing daemon 24. Further, the wireless interface module 16 receives the average received signal strength RSSI_AVE from the routing daemon 24 when each wireless device 31 to 43 receives a Hello packet from an adjacent wireless device. Further, the wireless interface module 16 receives the packet loss rate PKT_LOSS from the MAC module 17. Then, the wireless interface module 16 determines the transmission rate txRate in each wireless section based on the received topology information TPIF, average received signal strength RSSI_AVE, and packet loss rate PKT_LOSS by a method described later, and the determined transmission The rate txRate is output to the IP module 20. When receiving the packet from the upper layer, the wireless interface module 16 transmits the received packet at the determined transmission rate.

  The MAC module 17 belongs to the MAC layer, executes the MAC protocol, and executes various functions described below.

  That is, the MAC module 17 advertises the Hello packet received from the routing daemon 24 via the wireless interface module 16. The MAC module 17 takes out the packet from the buffer 18 and transmits the taken-out packet at the transmission rate received from the IP module 20. Further, the MAC module 17 performs retransmission control of data (packets). Then, the MAC module 17 detects the unicast retransmission rate as the packet loss rate PKT_LOSS, and outputs the detected packet loss rate PKT_LOSS to the wireless interface module 16 and the routing daemon 24.

  The buffer 18 belongs to the data link layer and temporarily stores packets. The LLC module 19 belongs to the data link layer and executes the LLC protocol to connect and release a link with an adjacent wireless device.

  The IP module 20 belongs to the Internet layer and receives the packet loss rate PKT_LOSS from the routing daemon 24. Based on the received packet loss rate PKT_LOSS, the IP module 20 determines a metric of a radio link formed between the radio device 31 and the radio devices 32 and 37 adjacent to the radio device 31 by a method described later. To do.

  Further, the IP module 20 smoothes the past value of the metric set in the wireless link formed between the wireless device 31 and the wireless devices 32 and 37 adjacent to the wireless device 31 by a method described later, and smoothes the smoothing. The converted metric is output to the routing daemon 24.

    Further, the IP module 20 transmits the transmission rate when transmitting packets at multi-rate to the MAC module 17.

  Furthermore, the IP module 20 generates an IP packet. The IP packet includes an IP header and an IP data part for storing a packet of a higher protocol. Then, when receiving data from the TCP module 22, the IP module 20 stores the received data in the IP data portion and generates an IP packet.

  Then, the IP module 20 searches the routing table 21 according to the OLSR protocol, which is a table-driven routing protocol, and determines a route for transmitting the generated IP packet. Then, the IP module 20 transmits the IP packet to the LLC module 19 and transmits the IP packet to the transmission destination along the determined path.

  The routing table 21 belongs to the Internet layer and stores path information in association with each transmission destination, as will be described later.

  The TCP module 22 belongs to the transport layer and generates a TCP packet. The TCP packet is composed of a TCP header and a TCP data part for storing data of an upper protocol. Then, the TCP module 22 transmits the generated TCP packet to the IP module 20.

  The UDP module 23 belongs to the transport layer, advertises a control packet created by the routing daemon 24, receives a control packet advertised from another wireless device, and outputs it to the routing daemon 24.

  The routing daemon 24 belongs to the process / application layer, monitors the execution state of other communication control modules, and processes requests from other communication control modules.

  Further, the routing daemon 24 calculates an optimum route based on the route information of the Hello packet received from another wireless device, and dynamically creates the routing table 21 in the Internet layer.

  Further, when the routing daemon 24 receives the smoothed metric from the IP module 20, it updates the routing table 21 with the received metric.

  Note that each of the wireless devices 32 to 43 illustrated in FIG. 1 has the same configuration as the configuration of the wireless device 31 illustrated in FIG. 2.

  FIG. 3 is a configuration diagram of a packet PKT in the OLSR protocol. The packet PKT includes a packet header PHD and message headers MHD1, MHD2,. Note that the packet PKT is transmitted and received using the port number 698 of the UDP module 23.

  The packet header PHD includes a packet length and a packet sequence number. The packet length consists of 16-bit data and represents the number of bytes of the packet. The packet sequence number consists of 16-bit data and is used to distinguish which packet is new. The packet sequence number is incremented by “1” every time a new packet is generated. Therefore, the larger the packet sequence number, the newer the packet PKT.

  Each of the message headers MHD1, MHD2,... Includes a message type, a valid time, a message size, a source address, a TTL, a hop count, a message sequence number, and a message.

  The message type is composed of 8-bit data and represents the type of message written in the message body, and 0 to 127 are reserved. The valid time consists of 8-bit data, and represents the time when this message must be managed after reception. The valid time is composed of a mantissa part and an exponent part.

  The message size consists of 16-bit data and represents the length of the message. The source address is made up of 32-bit data and represents the wireless device that generated the message. The TTL is composed of 8-bit data and specifies the maximum number of hops to which a message is transferred. The TTL is decremented by “1” when the message is transferred. If the TTL is “0” or “1”, the message is not transferred. The number of hops consists of 8-bit data and represents the number of hops from the message generation source. The number of hops is initially set to “0” and is incremented by “1” every time it is transferred. The message sequence number consists of 16-bit data and represents an identification number assigned to each message. The message sequence number is incremented by “1” every time a message is created. The message is a message to be transmitted.

  In the OLSR protocol, various messages are transmitted and received using the packet PKT having the configuration shown in FIG.

  FIG. 4 is a configuration diagram of the routing table 21 shown in FIG. The routing table 21 includes a transmission destination, a next wireless device, and the number of hops. The transmission destination, the next wireless device, and the number of hops are associated with each other. “Destination” represents the IP address of the destination wireless device. “Next wireless device” represents the IP address of the wireless device to be transmitted next when transmitting the packet PKT to the transmission destination. “Hop number” represents the number of hops to the destination. For example, in FIG. 1, when wireless communication is performed between the wireless device 31 and the wireless device 42 through the route of the wireless device 31 -the wireless device 32 -the wireless device 36 -the wireless device 39 -the wireless device 42, the wireless device 32 “3” is stored as the number of hops in the routing table 21.

  FIG. 5 is a schematic diagram showing the configuration of the neighbor list NTBL. The neighbor list NTBL includes its own address and the address of the adjacent wireless device. The own address and the address of the adjacent wireless device are associated with each other. The “self address” is composed of the IP address of the wireless device that creates the neighbor list NTBL. “Neighboring wireless device address” includes the IP address of the wireless device adjacent to the wireless device that creates the neighbor list NTBL.

  In the present invention, each of the wireless devices 31 to 43 creates the routing table 21 according to the OLSR protocol. The creation of the routing table 21 according to the OLSR protocol will be described in detail. When creating the routing table 21, the wireless devices 31 to 43 transmit and receive a Hello message and a TC message.

  The Hello message is periodically transmitted for the purpose of distributing information included in each of the wireless devices 31 to 43. By receiving this Hello message, each of the wireless devices 31 to 43 can collect information on peripheral wireless devices, and recognizes what wireless devices exist in the vicinity of the wireless devices.

  In the OLSR protocol, each of the wireless devices 31 to 43 manages local link information. The Hello message is a message for constructing and transmitting the local link information. The local link information includes “link set”, “neighboring wireless device set”, “two-hop neighboring wireless device set and link set to those wireless devices”, “MPR set”, and “MPR selector set”.

  A link set is a link to a set of wireless devices (adjacent wireless devices) through which radio waves directly reach, and each link is expressed by an effective time of a set of addresses between two wireless devices. The valid time is also used to indicate whether the link is unidirectional or bidirectional.

  The neighboring wireless device set is configured by the address of each neighboring wireless device, the retransmitting degree (Willingness) of the wireless device, and the like. The 2-hop adjacent wireless device set represents a set of wireless devices adjacent to the adjacent wireless device.

  The MPR set is a set of wireless devices selected as MPRs. Note that MPR means that when each packet PKT is transmitted to all the wireless devices 31 to 43 of the wireless network 100, each wireless device 31 to 43 transmits and receives one packet PKT only once, thereby transmitting all the packets PKT to all the wireless devices 31 to 43. The relay wireless device is selected so that it can be transmitted to the wireless devices 31 to 43.

  The MPR selector set represents a set of wireless devices that have selected themselves as MPRs.

  The process of establishing local link information is generally as follows. In the initial stage of the Hello message, each wireless device 31 to 43 transmits a Hello message containing its own address to an adjacent wireless device in order to notify its existence. All of the wireless devices 31 to 43 perform this operation, and each of the wireless devices 31 to 43 grasps what address the wireless device has around itself. In this way, a link set and an adjacent wireless device set are constructed.

  The constructed local link information is continuously sent again by a Hello message again. By repeating this, it is gradually clarified whether each link is bidirectional or what kind of wireless device exists ahead of the adjacent wireless device. Each of the wireless devices 31 to 43 stores the local link information that is gradually constructed in this way.

  Further, information regarding MPR is also periodically transmitted by a Hello message and notified to each of the wireless devices 31 to 43. Each of the wireless devices 31 to 43 selects several wireless devices from among neighboring wireless devices as a set of MPRs as wireless devices that request retransmission of the packet PKT transmitted by itself. Then, since the information regarding the MPR set is transmitted to the adjacent wireless device by the Hello message, the wireless device that has received the Hello message sets the set of wireless devices that have selected itself as the MPR as the “MPR selector set”. to manage. By doing in this way, each radio | wireless apparatus 31-43 can recognize immediately which packet apparatus PKT received should be retransmitted.

  When a local link set is established in each of the wireless devices 31 to 43 by transmission / reception of the Hello message, a TC message for notifying the topology of the entire wireless network 100 is transmitted to the wireless devices 31 to 43. This TC message is periodically transmitted by all wireless devices selected as MPRs. Since the TC message includes a link between each wireless device and the MPR selector set, all the wireless devices 31 to 43 of the wireless network 100 know all the MPR sets and all the MPR selector sets. Based on all the MPR sets and all the MPR selector sets, the topology of the entire wireless network 100 can be known. Each of the wireless devices 31 to 43 calculates the shortest path using the topology of the entire wireless network 100 and creates a route table based on the calculated shortest path.

  In addition, each radio | wireless apparatus 31-43 exchanges a TC message frequently separately from a Hello message. MPR is also used for exchanging TC messages.

  Each of the wireless devices 31 to 43 transmits and receives the above-described Hello message and TC message, recognizes the topology of the entire wireless network 100, calculates the shortest path based on the recognized topology of the entire wireless network 100, and based on this Thus, the routing table 21 shown in FIG. 4 is dynamically created.

  FIG. 6 is a diagram illustrating an example of a neighbor list. The wireless devices 32 and 37 create and send Hello messages = [IPaddress32] and [IPaddress37] including their own IP addresses, and the routing daemon 24 of the wireless device 31 sends Hello messages = [IPaddress32] and Hello messages = [ IPaddress 37] is directly received from the wireless devices 32 and 37, respectively.

  Then, the routing daemon 24 of the wireless device 31 creates a neighbor list NTBL_31 in the wireless device 31 based on Hello message = [IPaddress 32] and Hello message = [IPaddress 37] (see FIG. 6A).

  Then, the routing daemon 24 of the wireless device 31 creates and transmits a Hello message including the neighbor list NTBL_31. Then, the routing daemon 24 of the wireless device 31 creates a TC message including the IP address of the wireless device that is the MPR for the wireless device 31 and floods the wireless network 100 with the TC message.

  Also, the wireless device 32 creates a neighbor list NTBL_32 (see FIG. 6B) by the above-described operation, and creates and transmits a Hello message including the created neighbor list NTBL_32. Thus, the routing daemon 24 of the wireless device 31 that has received the Hello message including the neighbor list NTBL_32 can know what wireless device is present in the 2-hop area from the wireless device 31. Then, the wireless device 32 creates a TC message including the IP address of the wireless device that is an MPR for the wireless device 32 and floods it in the wireless network 100.

  Further, the wireless device 36 creates a neighbor list NTBL_36 (see (c) of FIG. 6) by the above-described operation, and creates and transmits a Hello message including the created neighbor list NTBL_36. Thereby, the routing daemon 24 of the wireless device 32 that has received the Hello message including the neighbor list NTBL_36 can know what wireless device is present in the 2-hop area from the wireless device 32. Then, the wireless device 36 creates a TC message including the IP address of the wireless device, which is an MPR for the wireless device 36, and floods it in the wireless network 100.

  Further, the other wireless devices 33 to 35 and 37 to 43 also create their own neighbor lists NTBL_33 to NTBL_35 and NTBL37 to NTBL_43 by the above-described operation, and include the created neighbor lists NTBL_33 to NTBL_35 and NTBL37 to NTBL_43. A message is created and transmitted, and a TC message including an IP address of a wireless device that is an MPR for itself is created and flooded in the wireless network 100.

  Through the above-described operation, the wireless device 31 can know the wireless devices 35, 36, and 41 existing in the 2-hop area from itself, and can also know the wireless device that is the MPR for the wireless devices 32 to 43.

  FIG. 7 is a conceptual diagram of topology information. Note that the topology information TPIF illustrated in FIG. 7 does not indicate the complete topology of the wireless devices 31 to 43 configuring the wireless network 100, and a part of the topology is missing.

  In the wireless device 31, the routing daemon 24 knows the wireless devices 35, 36, and 41 existing in a 2-hop area from the wireless device 31 and knows the wireless device that is the MPR for the wireless devices 32 to 43. Topology information TPIF indicating the topology of the wireless devices 31 to 43 configuring the wireless network 100 is created.

  Hereinafter, a method for determining the transmission rate txRate in each radio section will be described. The transmission rate txRate in each wireless section is determined using the data arrival status to the wireless device configuring each wireless section. In the present invention, the data arrival status includes an average received signal strength RSSI_AVE and a packet loss rate PKT_LOSS.

[Determination of transmission rate]
FIG. 8 is a diagram for explaining a method of detecting the data arrival status in each radio section.
(1) Detection of data arrival status The wireless devices 32, 35, 37, 38, 39, 41 receive data arrival status (average received signal strength RSSI_AVE and packet loss rate PKT_LOSS when transmitting a Hello packet from itself to the wireless device 36. The transmission rate is switched to a plurality of transmission rates, and the Hello packet is transmitted to the wireless device 36. More specifically, the IP modules 20 of the wireless devices 32, 35, 37, 38, 39, 41 sequentially output a plurality of transmission rates to the MAC module 17 as transmission rates when transmitting Hello packets. Then, the MAC module 17 of the wireless devices 32, 35, 37, 38, 39, 41 transmits a Hello packet at the transmission rate received from the IP module 20.

  In this case, the IP modules 20 of the wireless devices 32, 35, 37, 38, 39, and 41 sequentially switch the transmission rate to a plurality of transmission rates by the following three methods.

(MTH1)
The scheme MTH1 is a scheme that switches the transmission rate periodically. That is, in the method MTH1, the transmission rate is 54 Mbps, 6 Mbps, 48 Mbps, 9 Mbps, 36 Mbps, 12 Mbps, 24 Mbps, 18 Mbps, 54 Mbps, 6 Mbps, 48 Mbps, 9 Mbps, 36 Mbps, 12 Mbps, 24 Mbps,. It is switched in order. That is, in the scheme MTH1, the transmission rate is sequentially switched to a plurality of transmission rates in a cycle of [54 Mbps, 6 Mbps, 48 Mbps, 9 Mbps, 36 Mbps, 12 Mbps, 24 Mbps, 18 Mbps].

  By using this method MTH1, there is an advantage that the packet loss rate PKT_LOSS at all transmission rates can be measured relatively quickly.

(MTH2)
The system MTH2 is a system that periodically mixes transmission at a base rate. For example, 6 Mbps is used as the base rate. That is, in the method MTH2, the transmission rate is: 54 Mbps, 6 Mbps, 48 Mbps, 6 Mbps, 36 Mbps, 6 Mbps, 24 Mbps, 6 Mbps, 18 Mbps, 6 Mbps, 12 Mbps, 6 Mbps, 9 Mbps, 6 Mbps,. .., 54 Mbps, 9 Mbps, 6 Mbps, 48 Mbps, 12 Mbps, 6 Mbps, 36 Mbps, 18 Mbps, 6 Mbps, 24 Mbps, 6 Mbps,... That is, in the method MTH2, the transmission rate is such that the Hello packet is always transmitted at the base rate (= 6 Mbps) after transmitting the Hello packet at one or more transmission rates higher than the base rate (= 6 Mbps). The transmission rate is sequentially switched to a plurality of transmission rates.

  By using this method MTH2, since the transmission of the Hello packet at the base rate (= 6 Mbps) appears periodically, there is an advantage that the establishment of each radio section is stabilized.

(MTH3)
The system MTH3 is a system that gradually mixes transmission at a high rate. That is, in the method MTH3, the transmission rate is ..., 6 Mbps, 6 Mbps, 6 Mbps, ..., 6 Mbps, 9 Mbps, 6 Mbps, ..., 6 Mbps, 12 Mbps, 6 Mbps, 9 Mbps, 6 Mbps, ..., 6 Mbps, 54 Mbps, 6 Mbps, 48 Mbps, 6 Mbps, 36 Mbps,..., 9 Mbps, 6 Mbps,.

  That is, in the method MTH3, the transmission rate is dynamically changed according to the measured packet loss rate PKT_LOSS. More specifically, the scheme MTH3 mixes a high rate transmission rate when the packet loss rate PKT_LOSS is relatively low, and mixes a low rate transmission rate when the packet loss rate PKT_LOSS is relatively high.

  In addition, when there are a plurality of wireless devices, the method MTH3 determines the transmission rate according to the average value, intermediate value, minimum value and maximum value of the packet loss rate, the value of an important wireless section (MPR set wireless section), or the like. Change dynamically. Which one is to be adopted is determined by system characteristics, and each value can be combined.

  By using this method MTH3, there are advantages that the establishment of each radio section is stabilized and the packet loss rate PKT_LOSS at the minimum necessary transmission rate can be measured. Further, by changing the length of the packet used for measuring the packet loss rate PKT_LOSS, more precise measurement is possible, and there is an advantage that the transmission rate txRate can be determined more accurately.

  Note that the plurality of usable transmission rates are determined by the communication protocol used. When IEEE802.11a is used as the communication protocol, the plurality of transmission rates are 6 Mbps (= base rate), 9 Mbps, 12 Mbps, 18 Mbps, 24 Mbps, 36 Mbps, 48 Mbps, and 54 Mbps. Further, when IEEE802.11b is used as a communication protocol, the plurality of transmission rates are 1 Mbps (= base rate), 2 Mbps, 5.5 Mbps, and 11 Mbps. Further, when IEEE802.11g is used as a communication protocol, a plurality of transmission rates are 1 Mbps (= base rate), 2 Mbps, 5.5 Mbps, 11 Mbps, 6 Mbps, 9 Mbps, 12 Mbps, 18 Mbps, 24 Mbps, 36 Mbps, 48 Mbps, and 54 Mbps. Consists of.

  Therefore, the IP module 20 of the wireless devices 32, 35, 37, 38, 39, 41 sequentially switches the transmission rate to a plurality of transmission rates by any one of the three methods MTH1 to MTH3 described above, and the MAC module 17 A Hello packet is periodically transmitted at the switched transmission rate.

  The wireless interface module 16 of the wireless device 36 periodically receives Hello packets from the wireless devices 32, 35, 37, 38, 39, and 41 (see FIG. 8A) and receives Hello packets. The signal strengths RSSI_32, RSSI_35, RSSI_37, RSSI_38, RSSI_39, RSSI_41 are detected, and the Hello packet and the received signal strengths RSSI_32, RSSI_35, RSSI_37, RSSI_38, RSSI_39, RSSI_41 are transmitted to the routing daemon 24.

  The routing daemon 24 of the wireless device 36 receives the Hello packet and the received signal strengths RSSI_32, RSSI_35, RSSI_37, RSSI_38, RSSI_39, and RSSI_41 from the wireless interface module 16. Then, the routing daemon 24 of the wireless device 36 calculates the average received signal strength RSSI_AVE_32 based on the plurality of received signal strengths RSSI_32 received within a certain period. Similarly, the routing daemon 24 of the wireless device 36 includes a plurality of received signal strengths RSSI_35, a plurality of received signal strengths RSSI_37, a plurality of received signal strengths RSSI_38, a plurality of received signal strengths RSSI_39, and a plurality of received signal strengths RSSI_41, respectively. Based on the above, average received signal strengths RSSI_AVE_35, RSSI_AVE_37, RSSI_AVE_38, RSSI_AVE_39, RSSI_AVE_41 are calculated.

  In addition, the routing daemon 24 of the wireless device 36 receives packets per time at each transmission rate based on a plurality of Hello packets periodically received from the wireless devices 32, 35, 37, 38, 39, and 41 within a certain period. Loss rates PKT_LOSS_32, PKT_LOSS_35, PKT_LOSS_37, PKT_LOSS_38, PKT_LOSS_39, and PKT_LOSS_41 are detected.

  Then, the routing daemon 24 of the wireless device 36 includes the average received signal strength RSSI_AVE_32, RSSI_AVE_35, RSSI_AVE_37, RSSI_AVE_38, RSSI_AVE_39, RSSI_AVE_41, packet loss rates PKT_LOSS_32, PKT_LOSS_35, PKT_LOSS_35, PKT_LOSS_35, PKT_LOSS_35, PKT_LOSS_35, A Hello packet HELO including the IP addresses of 32, 35, 37, 38, 39, and 41 and the IP address of the wireless device 36 is created and advertised.

  The routing daemon 24 of the wireless device 32 receives the Hello packet HELO from the wireless device 36, and detects the average received signal strength RSSI_AVE_32 and the packet loss rate PKT_LOSS_32 at each transmission rate from the received Hello packet HELO. Then, the routing daemon 24 of the wireless device 32 outputs the detected average received signal strength RSSI_AVE_32 and the packet loss rate PKT_LOSS_32 at each transmission rate to the wireless interface module 16 and outputs the packet loss rate PKT_LOSS_32 to the IP module 20.

  The wireless interface module 16 of the wireless device 32 acquires the average received signal strength RSSI_AVE_32 and the packet loss rate PKT_LOSS_32 at each transmission rate.

  Similarly, the wireless interface modules 16 of the wireless devices 35, 37, 38, 39, and 41 also have an average received signal strength RSSI_AVE_35 and a packet loss rate PKT_LOSS_35 at each transmission rate, an average received signal strength RSSI_AVE_37, and a packet at each transmission rate, respectively. Loss rate PKT_LOSS_37, average received signal strength RSSI_AVE_38 and packet loss rate PKT_LOSS_38 at each transmission rate, average received signal strength RSSI_AVE_39, packet loss rate PKT_LOSS_39 at each transmission rate, and average received signal strength RSSI_AVE_41 and packet loss rate PKT_LOSS_41 at each transmission rate Obtain (see (b) of FIG. 8).

  The wireless devices 31, 33, 34, 40, 42, and 43 also receive the Hello packet HELO advertised from the wireless device 36. Therefore, the wireless interface module 16 of the wireless devices 31, 33, 34, 40, 42, and 43 is used. Are the average received signal strength RSSI_AVE_32 and the packet loss rate PKT_LOSS_32 at each transmission rate, the average received signal strength RSSI_AVE_35, and the respective transmissions when a Hello packet is transmitted from the wireless devices 32, 35, 37, 38, 39, and 41 to the wireless device 36. Packet loss rate PKT_LOSS_35 at the rate, average received signal strength RSSI_AVE_37 and packet loss rate PKT_LOSS_37 at each transmission rate, average received signal strength RSSI_AVE_38 and at each transmission rate Kettorosu rate PKT_LOSS_38, acquires the packet loss rate PKT_LOSS_41 in the average received signal strength RSSI_AVE_39 and packet loss rate PKT_LOSS_39 at each transmission rate, and the average received signal strength RSSI_AVE_41 and each transmission rate.

  In addition, the wireless interface module 16 of the wireless devices 31, 33, 34, 36, 40, 42, 43 is also changed from the wireless devices 31, 33, 34, 36, 40, 42, 43 to the adjacent wireless devices by the above-described operation. Data arrival status (consisting of the average received signal strength RSSI_AVE and the packet loss rate PKT_LOSS at each transmission rate) and the data arrival status are advertised in the wireless network 100.

  As a result, the wireless interface module 16 of each of the wireless devices 31 to 43 constituting the wireless network 100 allows the data arrival status (average received signal strength RSSI_AVE and packet loss rate PKT_LOSS at each transmission rate) in all wireless sections of the wireless network 100. To get).

(2) Determination of Transmission Rate txRate FIG. 9 is a functional block diagram of transmission rate determination means included in the wireless interface module 16 shown in FIG. The wireless interface module 16 includes a transmission rate determining unit 160. The transmission rate determining unit 160 includes a rate determining unit 1601 and a relation table 1602.

  The rate determining means 1601 receives the data arrival status (= average received signal strength RSSI_AVE and packet loss rate PKT_LOSS) and topology information TPIF in the entire radio section in the wireless network 100 from the routing daemon 24, and the data arrival status (= average reception). Based on the signal strength RSSI_AVE and the packet loss rate PKT_LOSS) and the relation table 1602, the transmission rate txRate in each radio section is determined.

  The relationship table 1602 holds the relationship between the average received signal strength RSSI_AVE and the reference transmission rate.

  FIG. 10 is a diagram showing the configuration of the relationship table 1602 shown in FIG. The relation table 1602 includes average received signal strength RSSI_AVE and a reference transmission rate. The average received signal strength RSSI_AVE and the reference transmission rate are associated with each other. More specifically, the 6 Mbps reference transmission rate is associated with an average received signal strength RSSI_AVE lower than −85 dB. Reference transmission rates of 9 Mbps, 12 Mbps, 18 Mbps, 24 Mbps, 36 Mbps, 48 Mbps, and 54 Mbps are −85 dB to −82 dB, −82 dB to −80 dB, −80 dB to −78 dB, −78 dB to −75 dB, −75 dB to, respectively. Corresponding to the average received signal strength RSSI_AVE of −72 dB, −72 dB to −65 dB, and −65 dB.

  FIG. 11 is a diagram illustrating the relationship between throughput and transmission rate. 11A shows the relationship between the throughput and the transmission rate when the packet size is 160 bytes, and FIG. 11B shows the relationship between the throughput and the transmission rate when the packet size is 500 bytes. FIG. 11C shows the relationship between the throughput when the packet size is 1000 bytes and the transmission rate. FIG. 11D shows the throughput when the packet size is 1500 bytes. The relationship with the transmission rate is shown.

  In (a) to (d) of FIG. 11, the vertical axis represents the throughput and the horizontal axis represents the transmission rate. Curves k1, k4, k7, and k10 show the relationship between the throughput and the transmission rate when there is no packet retransmission, and curves k2, k5, k8, and k11 show the packet retransmission rate when the packet retransmission rate is 20%. The relationship between throughput and transmission rate is shown. Curves k3, k6, k9, and k12 show the relationship between throughput and transmission rate when the packet retransmission rate is 40%.

  When the packet size is 160 bytes, the influence of the transmission rate on the throughput is small. As the packet size increases to 500 bytes, 1000 bytes, and 1500 bytes, the influence of the transmission rate on the throughput increases.

  In addition, when the packet size is 160 bytes, the throughput when considering packet retransmission is higher than the throughput when there is no packet retransmission compared to the case where there is no packet retransmission at a transmission rate of 12 Mbps. , When there is 20% retransmission at a transmission rate of 18 Mbps or higher, or when there is 40% retransmission at a transmission rate of 36 Mbps or higher (see curves k1 to k3).

  On the other hand, when the packet size is 500 bytes, the throughput when considering packet retransmission is higher than that when there is no packet retransmission compared to the case where there is no packet retransmission at a transmission rate of 12 Mbps. , When there is 20% retransmission at a transmission rate of 18 Mbps or higher, or when there is 40% retransmission at a transmission rate of 24 Mbps or higher (see curves k4 to k6). Also, when the packet size is 1000 bytes, the throughput when considering packet retransmission is higher than the throughput when there is no packet retransmission compared to the case where there is no packet retransmission at a transmission rate of 12 Mbps. , When there is 20% retransmission at a transmission rate of 18 Mbps or higher, or when there is 40% retransmission at a transmission rate of 24 Mbps or higher (see curves k7 to k9). Furthermore, when the packet size is 1500 bytes, the throughput when considering packet retransmission is higher than the throughput when there is no packet retransmission compared to the case where there is no packet retransmission at a transmission rate of 12 Mbps. , When there is 20% retransmission at a transmission rate of 18 Mbps or higher, or when there is 40% retransmission at a transmission rate of 24 Mbps or higher (see curves k10 to k12).

  As the packet size increases, the throughput is greatly improved regardless of whether or not the packet is retransmitted.

  Therefore, when the packet size is relatively large, it is advantageous to transmit the packet at a high transmission rate. When the packet size is relatively small, transmission at a high transmission rate causes a packet loss. Since it becomes larger, it is advantageous to transmit at a lower transmission rate.

  Rate determining means 1601 receives topology information TPIF, average received signal strength RSSI_AVE, and packet loss rate PKT_LOSS at each transmission rate from routing daemon 24. Further, the rate determining means 1601 holds the four relationship diagrams shown in FIG.

  FIG. 12 is a diagram for explaining a method of determining the transmission rate txRate. Upon obtaining the topology information TPIF, the average received signal strength RSSI_AVE, and the packet loss rate PKT_LOSS at each transmission rate, the rate determining unit 1601 refers to the relation table 1602 and detects the reference transmission rate txRate_STD corresponding to the average received signal strength RSSI_AVE. To do. In this case, it is assumed that the rate determination unit 1601 detects a reference transmission rate txRate_STD of 48 Mbps, for example.

  Then, the rate determining unit 1601 plots the relationship between the transmission rate and the packet loss rate PKT_LOSS in the vicinity of the detected reference transmission rate txRate_STD in the relationship between the throughput and the transmission rate considering the packet size (see FIG. 11). . In this case, for example, the rate determining unit 1601 may have a relationship P1 between a transmission rate of 36 Mbps and a packet loss rate PKT_LOSS of “0”, a relationship P2 of a transmission rate of 48 Mbps and a packet loss rate PKT_LOSS of “20%”, and 54 Mbps. The relationship P3 between the transmission rate of “40%” and the packet loss rate PKT_LOSS of “40%” is plotted.

  More specifically, when the packet size is 160 bytes, the rate determining unit 1601 shows the relations P1 to P3 between the transmission rates of 36 Mbps, 48 Mbps, and 54 Mbps and the packet loss rate PKT_LOSS as shown in FIG. And the transmission rate (see curves k1 to k3) (see (a) of FIG. 12). Further, when the packet size is 1500 bytes, the rate determining unit 1601 determines the relationship P4 to P6 between the transmission rate of 36 Mbps, 48 Mbps, and 54 Mbps and the packet loss rate PKT_LOSS as shown in (d) of FIG. (See curves k10 to k12) (see (b) of FIG. 12). 11A to 11D represent the packet loss rate PKT_LOSS, the packet loss rate PKT_LOSS of 0%, the packet loss rate PKT_LOSS of 20%, and the packet loss rate PKT_LOSS of 40% are These correspond to no retransmission, 20% retransmission rate, and 40% retransmission rate, respectively.

  When the relationship between the transmission rate and the packet loss rate PKT_LOSS is plotted in the vicinity of the reference transmission rate txRate_STD corresponding to the average received signal strength RSSI_AVE, the rate determining unit 1601 transmits the transmission rate that provides the maximum throughput from the plotted relationship. The rate is determined as txRate. More specifically, when the packet size is 160 bytes, the rate determining unit 1601 sets the packet loss rate PKT_LOSS to “0” at the 36 Mbps transmission rate and maximizes the throughput, so that 36 Mbps is set as the transmission rate txRate. decide. Further, when the packet size is 1500 bytes, the rate determining unit 1601 determines that the packet loss rate PKT_LOSS is “20%” and the throughput is maximum at the transmission rate of 48 Mbps, so that 48 Mbps is determined as the transmission rate txRate.

  The average received signal strength RSSI_AVE is −73 dB, and the packet loss rate PKT_LOSS at the transmission rates of 18 Mbps, 24 Mbps, 36 Mbps, 48 Mbps, and 54 Mbps is 0%, 20%, 20%, 40%, and 40%, respectively. In this case, the reference transmission rate txRate_STD corresponding to the average received signal strength RSSI_AVE of −73 dB is 36 Mbps (see FIG. 10). Then, when the relationship between the transmission rate and the packet loss rate PKT_LOSS in the vicinity of the reference transmission rate txRate_STD (= 36 Mbps) is plotted in the relationship diagram between the transmission rate and the throughput, “x” shown in (a) and (b) of FIG. It looks like a mark.

  As a result, when the packet size is 160 bytes, the throughput is about 5 Mbps at transmission rates of 18 Mbps, 36 Mbps, and 54 Mbps. Therefore, when the packet size is 160 bytes, the transmission rate txRate is determined to be 18 Mbps because there is no significant difference in throughput.

  On the other hand, when the packet size is 1500 bytes, the throughput is 14 Mbps at a transmission rate of 18 Mbps, the throughput is 20 Mbps at a transmission rate of 36 Mbps, and the throughput is 22 Mbps at a transmission rate of 54 Mbps.

  As a result, when the transmission is performed at the transmission rate of 54 Mbps, the throughput is maximized. Therefore, even though the packet loss rate PKT_LOSS is as high as 40%, the transmission rate of 54 Mbps is determined as the transmission rate txRate.

  Thus, when the packet size is large, even if the packet loss rate PKT_LOSS is high, the higher the transmission rate, the higher the throughput. Therefore, a relatively high transmission rate is determined as the transmission rate txRate.

  Note that, when the packet size is 500 bytes and 1000 bytes, the rate determining unit 1601 shows the relationship between the transmission rate near the reference transmission rate txRate_STD corresponding to the average received signal strength RSSI_AVE and the packet loss rate PKT_LOSS in FIG. ) And (c), the transmission rate txRate in each radio section is determined by the above-described method in addition to the relationship between the throughput and the transmission rate (curves k4 to k6 and k7 to k9).

[Metric smoothing]
FIG. 13 is a functional block diagram illustrating functions related to metric smoothing. The wireless interface module 16 includes a transmission rate determination unit 160 and a transmission / reception unit 161.

  The IP module 20 includes a metric determination unit 201, a smoothing unit 202, a route search unit 203, and a communication unit 204.

  Further, the routing daemon 24 includes an update unit 241 and a message creation unit 242.

  The transmission rate determining unit 160 determines the transmission rate by the method described above, and outputs the determined transmission rate to the transmitting / receiving unit 161 and the metric determining unit 201.

  The transmission / reception unit 161 receives a transmission rate from the transmission rate determination unit 160 and receives a packet (including a Hello message) from the communication unit 204. The transmission / reception unit 161 transmits the received packet at the transmission rate received from the transmission rate determination unit 160, receives the packet from another wireless device, and outputs the received packet to the communication unit 204.

  The metric determination unit 201 receives the transmission rate B from the transmission rate determination unit 160 and receives the packet loss rate PKT_LOSS at each transmission rate from the routing daemon 24. Then, the metric determination unit 201 detects the packet loss rate PKT_LOSS at the received transmission rate B, and calculates the ETX by substituting the detected packet loss rate PKT_LOSS into p in the following equation.

  Thereafter, the metric determination unit 201 calculates the metric m by substituting the ETX calculated using the equation (1), the packet size S, and the transmission rate B into the following equation.

  Then, the metric determination unit 201 outputs the calculated metric m to the smoothing unit 202.

The smoothing unit 202 sequentially receives the metric m from the metric determining unit 201, and holds a certain number n (n is an integer of 2 or more) of the sequentially received metric m. More specifically, when the smoothing unit 202 holds _n metrics m _{1 to} m _n and receives a new metric m _{n + 1} from the metric determination unit 201, the smoothing unit 202 discards the oldest metric m _1. , N metrics m _{2 to} m _{n + 1} are held. Note that the value of n is determined according to the characteristics of the wireless network 100.

The smoothing means 202, the n-number of the metric _m 1 ~m _n blunted with one of the following smoothing method HMTD1～HMTD3, obtaining the smoothed metric _{M i.}

(HMTD1)
Smoothing means 202, when smoothing the n-number of metrics _{m i- (n-1) ~m} i using smoothing methods HMTD1, next n number of metrics _{m i- (n-1) ~m} i Substituting into the equation and smoothing, we obtain the metric M _i .

That is, the smoothing means 202 to obtain the metric _{M i} by calculating the average of n metric _{m i- (n-1) ~m} i.

(HMTD2)
Smoothing means 202, when smoothing the n-number of metrics _{m i- (n-1) ~m} i using smoothing methods HMTD2, n-number of metrics _{m i- (n-1)} and ~m _i, the weights _w 0 _{to w n-1} and the n number is substituted into the following equation metric _{m i- (n-1) ~m} i smoothed to obtain a metric _{M i.}

In Expression (4), the weights w _{0 to} w _n−1 are determined according to the characteristics of the wireless network 100.

More specifically, the weights w _{0 to} w _n−1 are determined to be relatively large for relatively old metrics. In this case, a metric M _{i that} is resistant to fluctuations is obtained.

Further, the weights w _{0 to} w _n−1 are determined so as to be relatively large for a relatively new metric. In this case, a metric M _{i that} is sensitive to path changes is obtained.

Further, the weights w _{0 to} w _n−1 are determined so as to increase in a time zone in which the number of times of path switching is small. In this case, the path becomes stable.

(HMTD3)
Smoothing means 202, when smoothing the metric _{m i} using smoothing methods HMTD3, the metric _{m i} is smoothed by the following equation, to obtain a metric _{M i.}

That is, the smoothing means 202, variation smoothes the metric m _i to be less than the threshold value d.

For example, when the threshold value d is “3” and the measured values of the metrics are 2, 2, 2, and 7, the smoothing means 202 has a fluctuation range of “5” from “2” to “7”. , the fluctuation width of the threshold value d "3" greater than, instead of the "7""5" (= 2 + 3) and the metric _{M i.}

Further, the smoothing means 202 sets the threshold value d to “3”, and when the measured value of the metric is 7, 7, 7, 1, the fluctuation range from “7” to “1” is “6”. , fluctuation range the threshold d is "3" greater than, "1" instead of "4" (= 7-3) and a metric _{M i.}

Incidentally, smoothing means 202, when the fluctuation range of the metric m _i exceeds continuously the threshold d, it may be dynamically changing the threshold value d. For example, the smoothing means 202, when the threshold d "3", the fluctuation width of the metric m _i is more than 3 times in a row threshold d (= 3), the threshold the next time d Is “6”.

Smoothing means 202, the metric _{m i} received from the metric determining means 201 smoothes using any smoothing method of smoothing method HMTD1~HMTD3 described above, updating means 241 and message the smoothed metric _{M i} Output to the creating means 242.

  In response to a request from the communication unit 204, the route search unit 203 searches for a route to the transmission destination with reference to the routing table 21, and outputs the searched route to the communication unit 204.

  Upon receiving the Hello message from the message creation means 242, the communication means 204 sets the transmission destination to “BRODCAST”, creates a packet storing the Hello message in the data part, and sends the created packet via the transmission / reception means 161. advertise.

Further, when the communication unit 204 receives a Hello message transmitted from another wireless device from the transmission / reception unit 161, the communication unit 204 receives a metric M _i _EX (metric smoothed in the other wireless device) included in the received Hello message. The extracted metric M _i _EX is output to the update unit 241 and the message creation unit 242.

  Further, when the communication unit 204 receives data to be transmitted to the transmission destination from the message generation unit 242, the communication unit 204 stores the received data in the data part to generate a packet, and transmits the generated packet to the transmission destination. The route search unit 203 is requested to search for a route to be used. When the communication unit 204 receives a route from the route search unit 203, the communication unit 204 transmits a packet along the received route.

When the updating unit 241 receives the smoothed metric M _i from the smoothing unit 202 or receives the smoothed metric M _i _EX from the communication unit 204, the updating unit 241 receives the received metric M _i or M _i _EX. To update the routing table 21.

When the message creation means 242 receives the smoothed metric M _i from the smoothing means 202 or receives the smoothed metric M _i _EX from the communication means 204, the message creation means 242 receives the received metric M _i or M _i _EX. Is generated at a constant cycle T1 (for example, every 2 seconds) and output to the communication means 204.

  FIG. 14 is a flowchart for illustrating the communication method according to the first embodiment. When a series of operations is started, the transmission rate determination means 160 of each of the wireless devices 31 to 43 performs the wireless device according to the above-described method based on the data arrival status (= average received signal strength RSSI_AVE + packet loss rate PKT_LOSS). And a transmission rate in a radio link formed between adjacent radio devices adjacent to the radio device (step S1).

  Then, the transmission rate determination unit 160 of each of the wireless devices 31 to 43 outputs the determined transmission rate to the transmission / reception unit 161 and the metric determination unit 201.

Based on the transmission rate received from the transmission rate determination unit 160 and the packet loss rate PKT_LOSS received from the routing daemon 24, the metric determination unit 201 of each wireless device 31 to 43 uses the above-described method to establish a connection with the adjacent wireless device. determining the metric _{m i} of the radio link between (step S2), and outputs the determined metric _{m i} to the smoothing unit 202. That is, the metric determining means 201, in conjunction with the determination of the transmission rate in the transmission rate determining unit 160 determines the metric m _i.

The smoothing means 202 of each wireless device 31 to 43 is to smooth the metric _{m i} received from the metric determining means 201 by the method described above (step S3), and updating means 241 and message creating the smoothed metric _{M i} Output to the means 242.

Updating means 241 of the wireless device 31-43 updates the routing table 21 by the metric _{M i} received from the smoothing means 202 (step S4).

The message creation unit 242 of each wireless device 31 to 43 is to create a Hello message including the metric _{M i} received from the smoothing means 202 at a predetermined period T1 (= 2 second cycle), the communication means and the created Hello message To 204.

  And when the communication means 204 of each radio | wireless apparatus 31-43 receives the Hello message from the message preparation means 242, it sets "BROADCAST" as a transmission destination, stores a Hello message in a data part, produces a packet, The created packet is output to the transmission / reception means 161.

The transmission / reception unit 161 of each of the wireless devices 31 to 43 transmits the packet received from the communication unit 204 at the transmission rate received from the transmission rate determination unit 160. Thereby, the smoothed metric M _i is advertised periodically (step S5).

  After that, when the communication unit 204 of each wireless device 31 to 43 receives data to be transmitted to the transmission destination from the message creation unit 242, the received data is stored in the data part to create a packet, and the created The route search means 203 is requested to search for a route for transmitting the packet to the transmission destination.

  In response to a request from the communication unit 204, the route searching unit 203 of each of the wireless devices 31 to 43 searches the route for transmitting the packet to the transmission destination with reference to the updated routing table 21 (step S6). ), And outputs the searched route to the communication means 204. And the communication means 204 of each radio | wireless apparatus 31-43 transmits a packet to a transmission destination along the path | route searched by the path | route search means 203 (step S7). As a result, the series of operations ends.

Note that the updating unit 241 of each of the wireless devices 31 to 43 also receives the metric M _i _EX included in the Hello message transmitted from the other wireless device from the communication unit 204 even when the metric M _i _EX is received in step S4. The routing table 21 is updated. Further, when the message creation means 242 of each of the wireless devices 31 to 43 receives the metric M _i _EX included in the Hello message transmitted from the other wireless device from the communication means 204, the metric M _i _EX is also received in step S5. Is created and advertised at a constant period T1.

As described above, according to the first embodiment, each wireless device 31 to 43 is configured to advertise the metric M _i obtained by smoothing the metric m _i of the radio links formed between the self and the adjacent radio devices updates the routing table 21 by the smoothed metric M _i, and transmits the packet by searching for a route to the destination using the routing table 21 that the update.

  As a result, the fluctuation range of the metric of the wireless link formed between two adjacent wireless devices in the wireless network 100 is reduced, and the number of times of path switching is reduced.

  Therefore, according to the present invention, the wireless network 100 can be stabilized.

[Embodiment 2]
FIG. 15 is a schematic block diagram showing a configuration of the radio apparatus 31 shown in FIG. 1 in the second embodiment. The wireless device 31 shown in FIG. 1 includes the wireless device 31A shown in FIG. 15 in the second embodiment.

  The wireless device 31A is the same as the wireless device 31 except that the communication control unit 15 of the wireless device 31 shown in FIG.

  The communication control unit 15A is the same as the communication control unit 15 except that the IP module 20 and the routing daemon 24 of the communication control unit 15 shown in FIG.

IP module 20A is determined based on the transmission rate metrics of radio links formed between the adjacent radio devices adjacent to the wireless device 31A and the wireless device 31A, the determined metric m _i without smoothing Output to the routing daemon 24A.

  The IP module 20A performs the same functions as the IP module 20 in other respects.

Routing daemon 24A receives the metric _{m i} from the IP module 20A, updates the routing table 21 by the received metric _{m i,} to create a Hello message including the metric _{m i,} the created Hello message, adjust Advertise at the transmission timing.

  The routing daemon 24A performs the same functions as the routing daemon 24.

  Note that each of the wireless devices 32 to 43 illustrated in FIG. 1 includes the wireless device 31A illustrated in FIG.

  FIG. 16 is a functional block diagram illustrating a function of adjusting the timing for updating a metric. The IP module 20A is the same as the IP module 20 except that the smoothing means 202 of the IP module 20 shown in FIG.

In the IP module 20A, the metric determination unit 201 outputs the determined metric _mi to the update unit 241, the message creation unit 242, and the transmission timing adjustment unit 243.

  The routing daemon 24A is the same as the routing daemon 24 except that transmission timing adjustment means 243 is added to the routing daemon 24 shown in FIG.

  The transmission timing adjustment unit 243 determines the transmission timing T_tx of the Hello message by the following method, and outputs the determined transmission timing T_tx to the message creation unit 242.

In the second embodiment, the message creation unit 242 receives the transmission timing T_tx from the transmission timing adjusting means 243, and updates the metric _{m i-1} to the metric _{m i,} a Hello message including the updated metric _{m i} Create and output to communication means 204.

(Transmission timing determination method 1)
The transmission timing adjustment unit 243 adjusts the transmission timing T_tx of the Hello message to a transmission cycle T2 (for example, a 10-second cycle) longer than the transmission cycle T1 of the Hello message in the first embodiment.

(Transmission timing determination method 2)
Transmission timing adjusting unit 243 sequentially receives the metric _{m i} from the metric determining means 201, a certain number of holding the received metric _{m i.} For example, the transmission timing adjustment unit 243 holds _n metrics m _{i− (n−1) to} m _i by the same method as the smoothing unit 202 in the first embodiment.

Then, the transmission timing adjusting unit 243 calculates the standard deviation of the held n metrics m _{i− (n−1) to} m _i and detects the timing when the calculated standard deviation is equal to or less than the threshold value. .

  Then, the transmission timing adjustment unit 243 outputs the detected timing to the message creation unit 242 as the transmission timing T_tx.

The transmission timing adjusting unit 243 may determine the transmission timing T_tx by combining the transmission timing T_tx determination method 1 and the transmission timing T_tx determination method 2 described above. In this case, the transmission timing adjustment unit 243 determines whether or not the standard deviation of the _n metrics m _{i− (n−1) to} m _i is equal to or less than the threshold value for each transmission cycle T2, and transmits the transmission cycle T2. when one of n at the timing of the metric _{m i- (n-1) ~m} i standard deviation of is equal to or less than the threshold value, to determine one of the timing of the transmission period T2 and the transmission timing T_tx.

  The determination method 1 of the transmission timing T_tx is a method of determining each timing of the transmission cycle T2 longer than the transmission cycle T1 in which the normal Hello message including the path information is advertised as the transmission timing T_tx.

The transmission timing T_tx determination method 2 is a method of determining a timing having a time interval equal to or longer than the transmission cycle T1 as the transmission timing T_tx. This is because, n-number of metrics _{m i- (n-1)} ~m If _i stable, n-number of metrics _{m i- (n-1} at the transmission timing of regular Hello message used to exchange routing information ₎ standard deviation of ~m _i is may become less than the threshold, if the n metric _{m i- (n-1) ~m} i is unstable than the transmission cycle T1 of normal Hello message This is because the standard deviation of the _n metrics m _{i− (n−1) to} m _i falls below the threshold value over a long time interval.

Therefore, transmission timing adjustment unit 243 determines a transmission timing T_tx of Hello messages containing metric _{m i} as advertisement transmission period T1 or more time intervals.

Here, in order to distinguish a Hello message advertised at a time interval equal to or greater than the transmission cycle T1 from a Hello message advertised at a normal transmission cycle T1, when denoted as Hello_CTL, the transmission timing adjustment means 243 generally , the transmission interval of the Hello message Hello_CTL including metric _{m i} is such that the above transmission interval of regular Hello message, determines the transmission timing T_tx the Hello message Hello_CTL.

  In the present invention, the Hello message Hello_CTL is referred to as a “first control packet”, and a normal Hello message is referred to as a “second control packet”.

As described above, the transmission timing T_tx determination method 1 determines the transmission timing T_tx of the Hello message Hello_CTL in the transmission cycle T2 longer than the transmission cycle T1 in which the normal Hello message including the path information is advertised. metric _{m i} advertised in the 100, than if the Hello message Hello_CTL was advertised in the transmission cycle T1, the number of updates in the wireless network 100 is reduced. In other words, the switching frequency of the metric m _i to be advertised in the wireless network 100 is reduced.

  As a result, the number of updates of the routing table 21 is also reduced, and path switching is also reduced. Therefore, the wireless network 100 can be stabilized.

Also, the determination method 2 transmission timing T_tx is a timing fluctuation range of n metric _{m i- (n-1) ~m} i is stable below the threshold and the transmission timing T_tx the Hello message Hello_CTL determined since, the metric m _i to be advertised in the wireless network 100 becomes a stable value.

  As a result, the number of updates of the routing table 21 decreases, and the number of path switching also decreases. Therefore, the wireless network 100 can be stabilized.

In addition, by advertising the Hello message Hello_CTL at the transmission timing T_tx determined by the transmission timing T_tx determination methods 1 and 2 (including the combination of the transmission timing T_tx determination methods 1 and 2), the wireless devices 31 to 43 are advertised. Even if the update timing of the routing table 21 is shifted, the wireless network 100 can be stabilized. This is because the switching times of the metrics m _i advertised is reduced in the wireless network 100, because the number of updates of the routing table 21 is reduced.

  FIG. 17 is a flowchart for explaining a communication method according to the second embodiment. When a series of operations is started, the transmission rate determination means 160 of each of the wireless devices 31 to 43 performs the wireless device according to the above-described method based on the data arrival status (= average received signal strength RSSI_AVE + packet loss rate PKT_LOSS). And a transmission rate in a wireless link formed between the wireless device adjacent to the wireless device (step S11).

  Then, the transmission rate determination unit 160 of each of the wireless devices 31 to 43 outputs the determined transmission rate to the transmission / reception unit 161 and the metric determination unit 201.

Based on the transmission rate received from the transmission rate determination unit 160 and the packet loss rate PKT_LOSS received from the routing daemon 24, the metric determination unit 201 of each wireless device 31 to 43 uses the above-described method to establish a connection with the adjacent wireless device. determining the metric _{m i} of the radio link between (step S12), and outputs the determined metric _{m i} updating unit 241, the message creating means 242 and the transmission timing adjusting means 243. That is, the metric determining means 201, in conjunction with the determination of the transmission rate in the transmission rate determining unit 160 determines the metric updating means 241 the determined metric m _i without smoothing, the message creation unit 242 and the transmission timing Output to the adjusting means 243.

Then, the transmission timing adjusting means 243 of the wireless device 31 to 43, when receiving the metric _{m i} from the metric determining means 201 adjusts the transmit timing T_tx by the above-described method (step S13), and the transmission timing T_tx that the adjustment The message is output to the message creation means 242.

Message creating means 242 of the wireless device 31 to 43, when receiving the transmission timing T_tx from the transmission timing adjusting means 243, to create a Hello message Hello_CTL including metric _{m i,} outputs the created Hello message Hello_CTL to the communication unit 204 To do.

  Upon receiving the Hello message Hello_CTL from the message creation means 242, the communication means 204 of each of the wireless devices 31 to 43 sets “BROADCAST” as the transmission destination, stores the Hello message Hello_CTL in the data part, and creates a packet. The created packet is output to the transmission / reception means 161.

The transmission / reception unit 161 of each of the wireless devices 31 to 43 transmits the packet received from the communication unit 204 at the transmission rate received from the transmission rate determination unit 160. Thus, the metric _{m i} is advertised in synchronization with the adjusted transmission timing T_tx (step S14).

Thereafter, the update unit 241 of the wireless device 31-43 updates the routing table 21 by the metric _{m i} received from the metric determining means 201 (step S15).

  And the communication means 204 of each radio | wireless apparatus 31-43 will receive the data for transmitting to a transmission destination from the message preparation means 242, create the packet by storing the received data in a data part, and created the The route search means 203 is requested to search for a route for transmitting the packet to the transmission destination.

  In response to a request from the communication unit 204, the route search unit 203 of each wireless device 31 to 43 searches the route for transmitting the packet to the transmission destination with reference to the updated routing table 21 (step S16). ), And outputs the searched route to the communication means 204. And the communication means 204 of each radio | wireless apparatus 31-43 transmits a packet to a transmission destination along the path | route searched by the path | route search means 203 (step S7). As a result, the series of operations ends.

Incidentally, update means 241 of the wireless device 31 to 43, even when subjected to metric _m i _ex included in Hello messages Hello_CTL transmitted from another wireless device from the communication unit 204, at step S15, the metric _m i _ex To update the routing table 21. The message creation unit 242 of each wireless device 31 to 43, even when subjected to metric _m i _ex included in the transmitted Hello messages Hello_CTL from another wireless device from the communication unit 204, at step S14, the metric _{m i} A Hello message including _EX is created, and the created Hello message is advertised in synchronization with the transmission timing T_tx received from the transmission timing adjustment unit 243.

  FIG. 18 is a functional block diagram showing another function for adjusting the timing for updating a metric.

In the above description, and the metric m _i which is determined by the metric determining means 201 for advertising at a transmission timing T_tx adjusted by the transmission timing adjusting means 243, in the second embodiment is not limited thereto, and smoothed The metric M _i may be advertised at the transmission timing T_tx adjusted by the transmission timing adjustment unit 243.

  In this case, the functional block diagram is a functional block diagram in which the routing daemon 24 in the functional block diagram shown in FIG. 13 is replaced with the routing daemon 24A, and the IP module 20A shown in FIG. 16 is replaced with the IP module 20 shown in FIG. The routing daemon 24A is as described in FIG.

In the functional block diagram shown in FIG. 18, the metric determination unit 201 outputs the determined metric _mi to the smoothing unit 202 and the transmission timing adjustment unit 243.

Then, the message creating means 242 receives the transmission timing T_tx from the transmission timing adjusting means 243, and outputs to create a Hello message Hello_CTL including metric _{M i} received from the smoothing means 202 to the communication unit 204.

As a result, the smoothed metric M _i is advertised in synchronization with the transmission timing T_tx adjusted by the transmission timing adjustment unit 243.

  As a result, the metric advertised in the wireless network 100 is more stable, the number of updates of the routing table 21 is further reduced, and the wireless network 100 can be further stabilized.

If the wireless communication using the functional block diagram shown in FIG. 18 is performed, radio communication is performed according to the flowchart step is added to smooth the metric m _i between the steps S12 and Step S13 shown in FIG. 17 The In step 14, the smoothed metric M _i is advertised in synchronization with the adjusted transmission timing T_tx, and in step S 15, the routing table 21 is updated with the smoothed metric M _i .

  Therefore, the effects described above can be obtained.

  Others are the same as in the first embodiment.

[Embodiment 3]
FIG. 19 is a schematic block diagram showing the configuration of the wireless device 31 shown in FIG. 1 in the third embodiment. The wireless device 31 shown in FIG. 1 is composed of the wireless device 31B shown in FIG. 19 in the third embodiment.

  The wireless device 31B is the same as the wireless device 31A except that the communication control unit 15A of the wireless device 31A illustrated in FIG. 15 is replaced with a communication control unit 15B.

  The communication control unit 15B is the same as the communication control unit 15A except that the routing daemon 24A of the communication control unit 15A shown in FIG. 15 is replaced with a routing daemon 24B.

Routing daemon 24B receives the metric _{m i} from the IP module 20A, to create a Hello message including the received metric _{m i,} as well as advertisements that created Hello message transmission cycle T1, among a plurality of wireless devices synchronized, it updates the routing table 21 by the metric m _i.

  The routing daemon 24B otherwise performs the same function as the routing daemon 24.

  Note that each of the wireless devices 32 to 43 illustrated in FIG. 1 also includes the wireless device 31B illustrated in FIG.

  FIG. 20 is a functional block diagram showing a function of synchronizing the update timing for updating the routing table 21. The routing daemon 24B is the same as the routing daemon 24A except that the transmission timing adjustment unit 243 of the routing daemon 24A shown in FIG. 15 is replaced with the update timing synchronization unit 244.

Update timing synchronization means 244 receives the metrics _{m i} from the metric determining means 201 receives a Hello message transmitted from neighboring wireless device from the communication unit 204.

The update timing synchronization unit 244, based on the metric m _i _ex contained in metric m _i and Hello message, by a method described later, to take the synchronization of the update timing for updating the routing table 21 between a plurality of wireless devices The update timing is determined, the determined update timing is output to the updating means 241, and the determined update timing is advertised.

In the third embodiment, updating means 241, when receiving the update timing from the update timing synchronization means 244, in synchronization with the update timing thereof received, updates the routing table 21 by the metric m _i received from the metric determining means 201 To do.

  FIG. 21 is a diagram for explaining an operation of updating the routing table 21 in synchronization between a plurality of wireless devices. In addition, in FIG. 21, the operation | movement which updates the routing table 21 synchronously between radio | wireless apparatuses AD is demonstrated.

The update timing synchronization unit 244 of the wireless device A receives the metric m _i = AB_Metric = 3 from the metric determination unit 201, and communicates the metric m _i —EX = BA_Metric = 3 included in the Hello message transmitted from the wireless device B. Receive from.

  AB_Metric means a metric in the radio link in the direction from the radio apparatus A to the radio apparatus B, and BA_Metric means a metric in the radio link in the direction from the radio apparatus B to the radio apparatus A.

  Then, the update timing synchronization unit 244 of the wireless device A creates Hello message 1 = [AB_Metric = 3 / BA_Metric = 3] including the metric AB_Metric = 3 and the metric BA_Metric = 3, and the created Hello message 1 = [ [AB_Metric = 3 / BA_Metric = 3] is advertised through the communication unit 204 and the transmission / reception unit 161. As a result, the wireless devices B and C receive the Hello message 1.

  Thereafter, the update timing synchronization unit 244 of the wireless device B creates Hello message 2 = [BA_Metric = 3 / AB_Metric = 3] including the metric BA_Metric = 3 and the metric AB_Metric = 3, and the created Hello message 2 = [ [BA_Metric = 3 / AB_Metric = 3] is advertised through the communication unit 204 and the transmission / reception unit 161. As a result, the wireless devices A and D receive the Hello message 2.

  When the metric AB_Metric of the wireless link in the direction from the wireless device A to the wireless device B changes from “3” to “4”, the update timing synchronization means 244 of the wireless device A uses the metrics AB_Metric = 4 and metric BA_Metric = 3. Is generated, and the created Hello message 3 = [AB_Metric = 4 / BA_Metric = 3] is advertised via the communication unit 204 and the transmission / reception unit 161. That is, the wireless device A advertises only a change in the metric AB_Metric. As a result, the wireless devices B and C receive the Hello message 3.

  The update timing synchronization means 244 of the wireless device B recognizes that the metric AB_Metric has changed from “3” to “4” based on the received Hello message 3. However, the update timing synchronization means 244 of the wireless device B does not change the metric AB_Metric at the timing when the Hello message 3 is received.

  Then, the update timing synchronization unit 244 of the wireless device B creates a Hello message 4 = [BA_Metric = 3 / AB_Metric = 4] including the metric BA_Metric = 3 and the metric AB_Metric = 4, and the created Hello message 4 = [ [BA_Metric = 3 / AB_Metric = 4] is advertised through the communication unit 204 and the transmission / reception unit 161. As a result, the wireless devices A and D receive the Hello message 4.

  The update timing synchronization unit 244 of the wireless device A detects that the wireless device B has recognized the change of the metric AB_Metric based on the received Hello message 4. That is, the content advertised by the wireless device A is shared between the wireless devices A and B.

  Then, the update timing synchronization unit 244 of the wireless device A calculates an update time for updating the routing table 21 and obtains an update time T_update_MY = 3. This update time T_update_MY = 3 means that the metric AB_Metric = 4 should be reflected in the route after 3 seconds and the routing table 21 should be updated.

  Then, the update timing synchronization means 244 of the wireless device A receives the Hello message 5 = [AB_Metric = 4 / BA_Metric = 3 / T_update_MY = 3] including the metric AB_Metric = 4, the metric BA_Metric = 3, and the update time T_update_MY = 3. The created Hello message 5 = [AB_Metric = 4 / BA_Metric = 3 / T_update_MY = 3] is advertised through the communication unit 204 and the transmission / reception unit 161. As a result, the wireless devices B and C receive the Hello message 5.

  The update timing synchronization unit 244 of the wireless device B recognizes that the update time T_update = 3 is set based on the received Hello message 5, and transmits the time when the Hello message 5 is received and the next Hello message. The recalculation time is recalculated as 2.3 seconds from the time difference from the time to perform.

  The update timing synchronization means 244 of the wireless device B then sends a Hello message 6 = [BA_Metric = 3 / AB_Metric = 4 / T_update_REEX = 2.) Including metric BA_Metric = 3, metric AB_Metric = 4, and update time T_update_REEX = 2.3. 3], and the created Hello message 6 = [BA_Metric = 3 / AB_Metric = 4 / T_update_REEX = 2.3] is advertised through the communication unit 204 and the transmission / reception unit 161. As a result, the wireless devices A and D receive the Hello message 6.

  The update timing synchronization means 244 of the wireless device A recognizes that the update time is recalculated based on the received Hello message 6, recalculates the update time T_update_MY by the same method as the wireless device B, and updates the update time. Get T_update_REMY = 1.

  Then, the update timing synchronization unit 244 of the wireless device A sets the Hello message 7 = [AB_Metric = 4 / BA_Metric = 3 / T_update_REMY = 1] including the metric AB_Metric = 4, the metric BA_Metric = 3, and the update time T_update_REMY = 1. The created Hello message 7 = [AB_Metric = 4 / BA_Metric = 3 / T_update_REMY = 1] is advertised via the communication unit 204 and the transmission / reception unit 161. As a result, the wireless devices B and C receive the Hello message 7.

  Then, after transmitting the Hello message 7, the update timing synchronization unit 244 of the wireless device A outputs the update time T_update_REMY = 1 to the update unit 241, and the update unit 241 synchronizes with the update time T_update_REMY = 1, The route is recalculated by reflecting the metric AB_Metric = 4 received from the determination unit 201 in the route, and the routing table 21 is updated.

  Also, the update timing synchronization means 244 of the wireless devices B and C detects the metric AB_Metric = 4 and the update time T_update_REMY = 1 based on the received Hello message 7, and the detected metric AB_Metric = 4 and update time T_update_REMY = 1 is output to the updating means 241.

  Then, the updating unit 241 of the wireless devices B and C recalculates the route by reflecting the metric AB_Metric = 4 in the route in synchronization with the update time T_update_REMY = 1, and updates the routing table 21.

  Furthermore, the update timing synchronization means 244 of the wireless device D detects the metric AB_Metric = 4 and the update time T_update_REEX = 2.3 based on the received Hello message 6, and the detected metric AB_Metric = 4 and the update time T_update_REEX = 2.3 is output to the updating means 241.

  Then, the update unit 241 of the wireless device D recalculates the route by reflecting the metric AB_Metric = 4 in the route in synchronization with the update time T_update_REEX = 2.3, and updates the routing table 21.

  Thereby, the wireless devices A to D update the routing table 21 in synchronization.

As described above, the update timing synchronization unit 244 of the wireless device metric has changed in the direction of the radio links from the self to the adjacent wireless device metric AB_Metric changes due metric _m i (= AB_Metric) from metric determining means 201 When it is detected that, advertising by creating a Hello message including the metric m _i _change after the change, when receiving the Hello message indicating that it has recognized the change of the metrics from adjacent radio devices, advertising to set the update timing .

  When the update timing synchronization unit 244 that has detected the change in the metric receives a Hello message including the recalculated update time from the adjacent wireless device, the update timing synchronization unit 244 further recalculates the update time and includes the recalculated update time. Send a message.

  As described above, the update timing synchronization unit 244 that has detected the metric change recalculates and transmits the update time, and usually there are two adjacent wireless devices adjacent to the wireless device that has detected the metric change. This is because the update timing of the routing table 21 in the two adjacent wireless devices is synchronized.

  FIG. 22 is a flowchart for explaining a communication method according to the third embodiment. When a series of operations is started, the transmission rate determination means 160 of each of the wireless devices 31 to 43 performs the wireless device according to the above-described method based on the data arrival status (= average received signal strength RSSI_AVE + packet loss rate PKT_LOSS). And a transmission rate in a radio link formed between adjacent radio devices adjacent to the radio device (step S21).

  Then, the transmission rate determination unit 160 of each of the wireless devices 31 to 43 outputs the determined transmission rate to the transmission / reception unit 161 and the metric determination unit 201.

Based on the transmission rate received from the transmission rate determination unit 160 and the packet loss rate PKT_LOSS received from the routing daemon 24, the metric determination unit 201 of each wireless device 31 to 43 uses the above-described method to establish a connection with the adjacent wireless device. determining the metric _{m i} of the radio link between (step S22), and outputs the determined metric _{m i} updating unit 241, the message creating means 242 and the update timing synchronization unit 244. That is, the metric determination unit 201 determines a metric in conjunction with the transmission rate determination in the transmission rate determination unit 160, and outputs the determined metric _mi to the update unit 241, the message creation unit 242, and the update timing synchronization unit 244. To do.

The update timing synchronization unit 244 of the wireless device 31 to 43 determines, upon receiving the metric _{m i} from the metric determining means 201, the metric _{m i} is whether the change from the metric _{m i-1} (step S23) .

In step S23, the metric _{m i} is determined to have changed from the metric _{m i-1,} update timing synchronization unit 244 of the wireless device 31 to 43 advertises the Hello message containing the metric after the change (step S24 ).

  Thereafter, the update timing synchronization means 244 of each of the wireless devices 31 to 43 receives a message indicating that a change in metric has been recognized from one of the adjacent wireless devices adjacent to itself, and the update timing A Hello message including the message is created and advertised (step S25).

  Then, the update timing synchronization means 244 of each of the wireless devices 31 to 43 receives the update timing recalculated from one adjacent wireless device, further recalculates the update timing, and advertises it (step S26).

  Then, the updating unit 241 of each of the wireless devices 31 to 43 updates the routing table 21 using the metric after the change in synchronization with the update timing finally recalculated (Step S27).

  And the communication means 204 of each radio | wireless apparatus 31-43 will receive the data for transmitting to a transmission destination from the message preparation means 242, create the packet by storing the received data in a data part, and created the The route search means 203 is requested to search for a route for transmitting the packet to the transmission destination.

  In response to a request from the communication unit 204, the route search unit 203 of each wireless device 31 to 43 searches the route for transmitting the packet to the transmission destination with reference to the updated routing table 21 (step S28). ), And outputs the searched route to the communication means 204. Thereafter, the series of operations proceeds to step S30.

On the other hand, when it is determined in step S23 that the metric m _i has not changed from the metric m _i−1 , the communication unit 204 of each of the wireless devices 31 to 43 transmits the data to be transmitted to the transmission destination to the message creation unit. 242 is received, the received data is stored in the data portion, a packet is created, and a route search for transmitting the created packet to the transmission destination is requested to the route search means 203.

  Thereafter, the route searching unit 203 of each of the wireless devices 31 to 43 searches the route for transmitting the packet to the transmission destination with reference to the routing table 21 in response to the request from the communication unit 204 (step S29). .

  And after step S28 or step S29, the communication means 204 of each radio | wireless apparatus 31-43 transmits a packet to a transmission destination along the path | route searched by the path | route search means 203 (step S30). As a result, the series of operations ends.

  Note that the wireless devices around the wireless devices 31 to 43 also update the routing table 21 in synchronization with the timing at which the wireless devices 31 to 43 update the routing table 21 in step S27.

  As described above, according to the third embodiment, when the metric in one radio link changes, the plurality of radio apparatuses synchronously reflect the changed metric on the route and update the routing table 21.

  As a result, the plurality of wireless devices search for a route to the transmission destination based on the same routing table 21, and transmit a packet along the searched route. As a result, isotonicity is ensured, the route for transmitting the packet to the transmission destination becomes loop-free, and the optimum route to the transmission destination is guaranteed.

  Therefore, according to the present invention, the wireless network 100 can be stabilized.

  In the third embodiment, the functional block diagram showing the function of synchronizing the update timing for updating the routing table may be the functional block diagram shown in FIG.

  FIG. 23 is another functional block diagram showing the function of synchronizing the update timing for updating the routing table. The functional block diagram shown in FIG. 23 is obtained by adding smoothing means 202 to the functional block diagram shown in FIG.

In functional block diagram shown in FIG. 23, the smoothing means 202 outputs the smoothed metric _{M i} updating unit 241, the message creating means 242 and the update timing synchronization unit 244.

Then, the update timing synchronization unit 244 detects a change in the metric based on the smoothed metric M _i and synchronizes the update timing for updating the routing table 21 by the method described above.

The update unit 241 receives the update timing from the update timing synchronization means 244, in synchronization with the update timing thereof received, performs route calculation to reflect the path smoothed metric M _i, the routing table 21 Update.

Therefore, until the change in the metric M _i is detected, the routing table 21 is not updated, the change in the metric M _i is detected, as described above, the routing table 21, among a plurality of wireless devices Since it is updated synchronously, the wireless network 100 can be stabilized.

If the wireless communication using the functional block diagram shown in FIG. 23 is performed, radio communication is performed according to the flowchart step is added to smooth the metric m _i between the step S22 and the step S23 shown in FIG. 22 The In step 24, the changed metric M _i is advertised, and in step S27, the routing table 21 is updated with the smoothed metric M _i .

  Therefore, the same effect as described above can be obtained.

  Others are the same as in the first embodiment.

[Embodiment 4]
FIG. 24 is a schematic block diagram showing the configuration of the wireless device 31 shown in FIG. 1 in the fourth embodiment. The wireless device 31 shown in FIG. 1 includes the wireless device 31C shown in FIG. 24 in the fourth embodiment.

  A wireless device 31C is the same as the wireless device 31 except that the communication control unit 15 of the wireless device 31 shown in FIG.

  The communication control unit 15C is the same as the communication control unit 15 except that the IP module 20 of the communication control unit 15 shown in FIG.

  The IP module 20B determines a bidirectional metric in a wireless link formed between the wireless device 31C and one adjacent wireless device adjacent to the wireless device 31C, and smoothes the determined bidirectional metric. Output to the routing daemon 24.

  FIG. 25 is a functional block diagram for performing bidirectional metric determination and metric smoothing. The IP module 20B is the same as the IP module 20 except that the metric determination unit 201 of the IP module 20 shown in FIG.

  In the IP module 20B, when the communication unit 204 receives a Hello message transmitted from another wireless device from the transmission / reception unit 161, the communication unit 204 outputs the received Hello message to the metric determination unit 201A.

  Also, in the IP module 20, the transmission rate determining means 160 determines the transmission rate of the radio link in the direction from the radio apparatus on which it is mounted to the adjacent radio apparatus by the above-described method, and the determined transmission rate is a metric. The data is output to the determination unit 201A and the message creation unit 242.

  The metric determination unit 201A determines the metric of the radio link in the direction from the wireless device on which it is installed to the adjacent wireless device based on the communication quality actually measured by the wireless device on which it is installed, and smoothes the determined metric When the communication quality output to the means 202 and received by the adjacent wireless device is received from the adjacent wireless device, based on the communication quality actually measured by the wireless device on which it is mounted and the communication quality actually measured by the adjacent wireless device. The bidirectional metric of the wireless link formed with the adjacent wireless device is determined by the method to perform the determination, and the determined metric is output to the smoothing unit 202.

  Hereinafter, a method for determining a bidirectional metric will be described. In the description of the bidirectional metric determination method, two adjacent wireless devices are assumed to be wireless devices A and B, and the bidirectional metric determination method in the wireless device A will be described.

(Bidirectional metric determination method 1)
In the bidirectional metric determination method 1, the transmission rate determination means 160 of the wireless device B adjacent to the wireless device A that determines the bidirectional metric determines the transmission rate BA_Rate by the method described above, and the determined transmission. The rate BA_Rate is output to the metric determination unit 201A. The transmission rate BA_Rate is a transmission rate in the direction from the wireless device B to the wireless device A.

  Based on the transmission rate BA_Rate, the metric determination unit 201A of the wireless device B determines the metric BA_Metric by the method described above, and outputs the determined metric BA_Metric to the smoothing unit 202. The metric BA_Metric is a metric in the radio link in the direction from the radio apparatus B to the radio apparatus A.

  Then, the smoothing unit 202 of the wireless device B smoothes the metric BA_Metric received from the metric determining unit 201A and outputs the smoothed metric BA_Metric to the message creating unit 242.

  Then, the message creation unit 242 of the wireless device B creates Hello message = [BA_Metric] including the metric BA_Metric received from the smoothing unit 202, and advertises the created Hello message = [BA_Metric].

  On the other hand, the transmission rate determining unit 160 of the wireless device A determines the transmission rate AB_Rate by the method described above, and outputs the determined transmission rate AB_Rate to the metric determining unit 201A.

  Further, the transmission / reception unit 161 of the wireless device A receives the Hello message = [BA_Metric] transmitted from the wireless device B, and outputs the received Hello message = [BA_Metric] to the communication unit 204.

  Then, the communication unit 204 of the wireless device A extracts the metric BA_Metric from the Hello message = [BA_Metric], and outputs the extracted metric BA_Metric to the metric determination unit 201A.

  Then, the metric determination unit 201A of the wireless device A receives the transmission rate AB_Rate from the transmission rate determination unit 160, and receives the metric BA_Metric from the communication unit 204.

  Then, the metric determination unit 201A of the wireless device A determines the metric AB_Metric in the wireless link in the direction from the wireless device A to the wireless device B by the above-described method based on the received transmission rate AB_Rate.

Thereafter, the metric determining unit 201A of the wireless device A determines the larger one of the two metrics AB_Metric and BA_Metric as the bidirectional metric _MAＭB of the wireless link between the wireless device A and the wireless device B. Then, the metric determination unit 201A of the wireless device A outputs the determined bidirectional metric _MA⇔B to the smoothing unit 202.

Note that the metric determining means 201A is two metrics AB_Metric, may be determined as a two-way metrics _{M A⇔B} a minimum of BA_Metric, two metrics AB_Metric, bidirectional average value of BA_Metric metric M _{A⇔B may} be determined, and the sum of two metrics AB_Metric and BA_Metric _may be determined as a bidirectional metric MAＭB, and the product of the two metrics AB_Metric and BA_Metric may be a bidirectional metric _MA⇔. You may determine as _B.

When the metric determination unit 201A of the wireless device B receives the metric AB_Metric from the wireless device A, the metric determination unit 201A determines the bidirectional metric _MA⇔B by the same method as the metric determination unit 201A of the wireless device A.

  When the radio devices A and B determine the metrics AB_Metric and BA_Metric based on the transmission rates AB_Rate and BA_Rate determined by the radio devices A and B, respectively, the radio devices A and B advertise the determined metrics AB_Metric and BA_Metric. Each wireless device A and B recognizes the partner's metric for the first time when a Hello message is received from the partner.

Therefore, in the bidirectional metric determination method 1, the wireless devices A and B can determine the bidirectional metric M _A⇔B synchronously.

(Bidirectional metric determination method 2)
In the bidirectional metric determination method 2, the transmission rate determination means 160 of the wireless device B adjacent to the wireless device A that determines the bidirectional metric determines the transmission rate BA_Rate by the method described above, and the determined transmission. The rate BA_Rate is output to the message creation means 242.

  The message creation unit 242 of the wireless device B receives the transmission rate BA_Rate from the transmission rate determination unit 160 and the packet loss rate AB_Loss from the routing daemon 24. The packet loss rate AB_Loss is a packet loss rate when a packet is transmitted from the wireless device A to the wireless device B.

  Then, the message creation unit 242 of the wireless device B creates a Hello message = [BA_Rate / AB_Loss] including the transmission rate BA_Rate and the packet loss rate AB_Loss, and advertises the created Hello message = [BA_Rate / AB_Loss]. .

  On the other hand, the transmission rate determining unit 160 of the wireless device A determines the transmission rate AB_Rate by the method described above, and outputs the determined transmission rate AB_Rate to the metric determining unit 201A.

  The transmission / reception unit 161 of the wireless device A receives the Hello message = [BA_Rate / AB_Loss] transmitted from the wireless device B, and outputs the received Hello message = [BA_Rate / AB_Loss] to the communication unit 204.

  Then, the communication unit 204 of the wireless device A extracts the transmission rate BA_Rate and the packet loss rate AB_Loss from the Hello message = [BA_Rate / AB_Loss], and outputs the extracted transmission rate BA_Rate and packet loss rate AB_Loss to the metric determination unit 201A. .

  Then, the metric determination unit 201A of the wireless device A receives the transmission rate AB_Rate from the transmission rate determination unit 160, receives the transmission rate BA_Rate and the packet loss rate AB_Loss from the communication unit 204, and receives the packet loss rate BA_Loss from the routing daemon 24.

  Then, the metric determination unit 201A of the wireless device A sets the larger transmission rate of the two transmission rates AB_Rate and BA_Rate as bit rate.

  Thereafter, the metric determination unit 201A of the wireless device A obtains the bidirectional error rate Error Rate in the wireless link between the wireless device A and the wireless device B by the following method based on the bit rate and the packet loss rates AB_Loss and BA_Loss. .

  Since the packet loss rates AB_Loss and BA_Loss are determined for each transmission rate (= bit rate) as described above, the metric determination unit 201A of the wireless device A uses the packet loss rate AB_Loss_r corresponding to the obtained bit rate. , BA_Loss_r.

  Each of the packet loss rates AB_Loss_r and BA_Loss_r consists of a value in the range of 0-1. In addition, since the IEEE802.11MAC receives the ACK using the wireless link in the reverse direction after transmitting the packet, the wireless communication in the direction from the wireless device A to the wireless device B and the wireless device B to the wireless device A are performed. Wireless communication between the wireless device A and the wireless device B is successful.

  Therefore, the probability that the wireless communication is successful in the wireless link between the wireless device A and the wireless device B is (the probability that the wireless communication in the direction of the wireless device A → the wireless device B is successful) (the wireless device B → the wireless device A The value multiplied by the probability of successful wireless communication in the direction), that is, (1−AB_Loss_r) × (1−BA_Loss_r).

  Then, the bidirectional error rate Error Rate in the wireless link between the wireless device A and the wireless device B is 1- (1-AB_Loss_r) × (1-BA_Loss_r).

  Therefore, the metric determination unit 201A of the wireless device A obtains the bidirectional error rate Error Rate by the method described above based on the bit rate and the packet loss rates AB_Loss and BA_Loss.

Then, the metric determination unit 201A of the wireless device A determines the bidirectional metric M A _⇔B based on the bit rate and the error rate.

More specifically, the metric determining unit 201A of the wireless device A calculates ETX by substituting the obtained Error Rate into p in the equation (1), and calculates the calculated ETX and the obtained bit rate (= B). Then, a known metric M _A⇔B is determined by substituting the known packet size (= S) into equation (2).

The metric determining unit 201A of the wireless device B also determines the bidirectional metric M _A⇔B by the same method as the metric determining unit 201A of the wireless device A.

  In the two-way metric determination method 2, the metric determination unit 201A may set the minimum value of the two transmission rates AB_Rate and BA_Rate as the bit rate, and the average value of the two transmission rates AB_Rate and BA_Rate. rate, or the sum of two transmission rates AB_Rate and BA_Rate may be used as a bit rate, and the product of the two transmission rates AB_Rate and BA_Rate may be used as a bit rate.

(Bidirectional metric determination method 3)
In the bidirectional metric determination method 3, the wireless interface module 16 of the wireless device B adjacent to the wireless device A that determines the bidirectional metric receives the Hello message from the wireless device A as described above. The received signal strength AB_RSSI is detected, and the detected received signal strength AB_RSSI is output to the routing daemon 24.

  Then, the message creation means 242 of the wireless device B receives the received signal strength AB_RSSI from the wireless interface module 16 and the packet loss rate AB_Loss from the routing daemon 24.

  Then, the message creation unit 242 of the wireless device B creates a Hello message = [AB_RSSI / AB_Loss] including the received signal strength AB_RSSI and the packet loss rate AB_Loss, and advertises the created Hello message = [AB_RSSI / AB_Loss]. To do.

  On the other hand, when the transmission / reception unit 161 of the wireless device A receives the Hello message = [AB_RSSI / AB_Loss] from the wireless device B, the transmission / reception means 161 detects the received signal strength BA_RSSI when the Hello message = [AB_RSSI / AB_Loss] is received. The received signal strength BA_RSSI and Hello message = [AB_RSSI / AB_Loss] are output to the communication means 204.

  When receiving the received signal strength BA_RSSI and the Hello message = [AB_RSSI / AB_Loss] from the transmitting / receiving unit 161, the communication unit 204 of the wireless device A extracts the received signal strength AB_RSSI and the packet loss rate AB_Loss from the Hello message = [AB_RSSI / AB_Loss]. The received signal strength BA_RSSI, the received signal strength AB_RSSI, and the packet loss rate AB_Loss are output to the metric determining means 201A.

  The metric determination unit 201A of the wireless device A receives the received signal strength BA_RSSI, the received signal strength AB_RSSI and the packet loss rate AB_Loss from the communication unit 204, and receives the packet loss rate BA_Loss from the routing daemon 24. In addition, the metric determination unit 201A of the wireless device A holds a relation table 1602 shown in FIG.

  Then, the metric determination unit 201A of the wireless device A refers to the relation table 1602 to obtain the transmission rate AB_Rate corresponding to the reception signal strength AB_RSSI and the transmission rate BA_Rate corresponding to the reception signal strength BA_RSSI, and the obtained 2 Of the two transmission rates AB_Rate and BA_Rate, the larger one is defined as bit rate.

  Then, the metric determination means 201A of the wireless device A uses the same method as that of the bidirectional metric determination method 2 based on the obtained bit rate and the two packet loss rates AB_Loss and BA_Loss, to determine the error rate Error. Get the Rate.

After that, the metric determination unit 201A of the wireless device A determines the bidirectional metric M _A⇔B by the same method as the bidirectional metric determination method 2 based on the bit rate and the error rate Error Rate. .

The metric determining unit 201A of the wireless device B also determines the bidirectional metric M _A⇔B by the same method as the metric determining unit 201A of the wireless device A.

  In the bidirectional metric determination method 3 as well, the metric determination means 201A may set the minimum value of the two transmission rates AB_Rate and BA_Rate as the bit rate, and the average value of the two transmission rates AB_Rate and BA_Rate. rate, or the sum of two transmission rates AB_Rate and BA_Rate may be used as a bit rate, and the product of the two transmission rates AB_Rate and BA_Rate may be used as a bit rate.

  In the bi-directional metric determination method 3, it is unnecessary to calculate the transmission rates AB_Rate and BA_Rate in the wireless devices A and B and exchange the transmission rates AB_Rate and BA_Rate between the wireless device A and the wireless device B. Further, by using the same algorithm as the algorithm for controlling the transmission rate, the change in the transmission rate can be reflected in the metric as it is.

(Bidirectional metric determination method 4)
In the bidirectional metric determination method 4, the message creation unit 242 of the wireless device B adjacent to the wireless device A that determines the bidirectional metric receives the packet loss rate AB_Loss from the routing daemon 24.

  Then, the message creation unit 242 of the wireless device B creates Hello message = [AB_Loss] including the packet loss rate AB_Loss, and advertises the created Hello message = [AB_Loss].

  On the other hand, the transmission / reception unit 161 of the wireless device A receives the Hello message = [AB_Loss] transmitted from the wireless device B, and outputs the received Hello message = [AB_Loss] to the communication unit 204.

  Then, the communication unit 204 of the wireless device A extracts the packet loss rate AB_Loss from the Hello message = [AB_Loss], and outputs the extracted packet loss rate AB_Loss to the metric determination unit 201A.

  Then, the metric determination unit 201A of the wireless device A receives the packet loss rate AB_Loss from the communication unit 204 and receives the packet loss rate BA_Loss from the routing daemon 24.

  Since each of the two packet loss rates AB_Loss and BA_Loss consists of packet loss rates corresponding to the transmission rates (54, 48, 36, 24, 18, 12, 9 Mbps), the metric determining means 201A of the wireless device A Uses the packet loss rates corresponding to the transmission rates of the two packet loss rates AB_Loss and BA_Loss to determine the error rate Error Rate for each transmission rate by the method described above.

  Thereafter, the metric determination unit 201A of the wireless device A calculates a metric for each transmission rate using the error rate Error Rate calculated for each transmission rate and the above-described equations (1) and (2).

Then, the metric determination unit 201A of the wireless device A determines the smallest metric among the obtained metrics for each transmission rate as the bidirectional metric _MA⇔B .

Note that the metric determining unit 201A of the wireless device B also determines the bidirectional metric _MA⇔B by the same method as the metric determining unit 201A of the wireless device A.

  In the bi-directional metric determination method 4, the wireless device A calculates the metric of the wireless device B from only the packet loss rate with little fluctuation, and therefore, the metric is advertised to some extent without any synchronization. it can.

(Bidirectional metric determination method 5)
In the bidirectional metric determination method 5, the message creation unit 242 of the wireless device B adjacent to the wireless device A that determines the bidirectional metric receives the packet loss rate AB_Loss from the routing daemon 24.

  Then, the message creation unit 242 of the wireless device B creates Hello message = [AB_Loss] including the packet loss rate AB_Loss, and advertises the created Hello message = [AB_Loss].

  On the other hand, the transmission / reception unit 161 of the wireless device A receives the Hello message = [AB_Loss] transmitted from the wireless device B, and outputs the received Hello message = [AB_Loss] to the communication unit 204.

  Then, the communication unit 204 of the wireless device A extracts the packet loss rate AB_Loss from the Hello message = [AB_Loss], and outputs the extracted packet loss rate AB_Loss to the metric determination unit 201A.

  Then, the metric determination unit 201A of the wireless device A receives the packet loss rate AB_Loss from the communication unit 204 and receives the packet loss rate BA_Loss from the routing daemon 24.

  Since each of the two packet loss rates AB_Loss and BA_Loss consists of packet loss rates corresponding to the transmission rates (54, 48, 36, 24, 18, 12, 9 Mbps), the metric determining means 201A of the wireless device A Uses the packet loss rates corresponding to the transmission rates of the two packet loss rates AB_Loss and BA_Loss to determine the error rate Error Rate for each transmission rate by the method described above.

  Thereafter, the metric determination unit 201A of the wireless device A calculates the metric A_AB_Metric for each transmission rate using the error rate Error Rate calculated for each transmission rate and the above-described equations (1) and (2).

  Then, the metric determination unit 201A of the wireless device A detects the transmission rate when the minimum metric is obtained from the metrics A_AB_Metric for each transmission rate, and sets the detected transmission rate as AB_Rate.

  Subsequently, the metric determining unit 201A of the wireless device A determines whether or not the obtained transmission rate AB_Rate is equal to or higher than a threshold value (= 24 Mbps), and the transmission rate AB_Rate is equal to or higher than the threshold value (= 24 Mbps). In some cases, the transmission rate BA_Rate is set to 24 Mbps.

  On the other hand, the metric determination unit 201A of the wireless device A sets the transmission rate BA_Rate to BA_Rate = AB_Rate when the transmission rate AB_Rate is smaller than the threshold value (= 24 Mbps).

  Then, the metric determination unit 201A of the wireless device A uses the metric (1) and (2) described above based on the obtained transmission rate BA_Rate and the value of the packet loss rate BA_Loss corresponding to the transmission rate BA_Rate. Obtain A_BA_Metric.

  Thereafter, the metric determination unit 201A of the wireless device A calculates the sum of the two obtained metrics A_AB_Metric and A_BA_Metric to obtain the metric A_Metric.

  Subsequently, the metric determination unit 201A of the wireless device A obtains the metric B_Metric by the same method as described above.

Then, the metric determination unit 201A of the wireless device A determines the larger metric among the metrics A_Metric and _{B_Metric} as the bidirectional metric _MA⇔B .

The metric determination unit 201A of the wireless device B also obtains the metric A_Metric and the metric B_Metric by the same method as the metric determination unit 201A of the wireless device A, and the larger metric of the obtained metric A_Metric and metric B_Metric is the bidirectional metric. _Determine as _{MA と し て B.}

The wireless device A, in B, and two-way metrics _{M A⇔B} is required, metric determining means 201A of the wireless device A creates a message through the smoothing means 202 metric _{M A⇔B} of the determined bidirectional The message creating means 242 of the wireless device A creates and advertises Hello message = [M A _{広 告 B} ] including the bidirectional metric M _A⇔B . Further, the metric determination means 201A of the wireless device B outputs the obtained bidirectional metric _MA⇔B to the message creation means 242 via the smoothing means 202, and the message creation means 242 of the wireless device B A Hello message = [M _A⇔B ] including the metric M _A⇔B is created and advertised.

In the bidirectional metric determination method 5, the metric determination unit 201A may determine the minimum value of the two metrics _{A_Metric and B_Metric} as the bidirectional metric _MA⇔B , and the two metrics A_Metric. , B_Metric _may be determined as a bi-directional metric M A _⇔B , and the sum of two metrics A_Metric and B_Metric _may be determined as a bi-directional metric M A ⇔B. The product of _{B_Metric} may be determined as a bi-directional metric _MA⇔B .

In each of the wireless devices 31 to 43, the metric determining unit 201A determines the bidirectional metric _MA⇔B using any one of the bidirectional metric determining methods 1 to 5 described above, and the determined bidirectional metric The metric M _A⇔B is output to the smoothing means 202.

In each of the wireless devices 31 to 43, the smoothing unit 202 smoothes the bidirectional metric M _AＭB by the method described above, and the smoothed metric M _A⇔B is updated by the updating unit 241 and the message creating unit 242. Output to.

The message creation unit 242 creates and advertises a Hello message including the metric M _A⇔B received from the smoothing unit 202, and the update unit 241 updates the routing table 21 with the metric M _A⇔B received from the smoothing unit 202. To do.

  FIG. 26 is a flowchart for illustrating a communication method according to the fourth embodiment. When a series of operations is started, the metric determination unit 201A of each of the wireless devices 31 to 43 is based on the communication quality in both directions of the wireless link formed between each of the wireless devices 31 to 43 and the adjacent wireless device. The bidirectional metric is determined by the above-described method (step S31), and the determined bidirectional metric is output to the smoothing means 202.

  Then, the smoothing means 202 of each of the wireless devices 31 to 43 smoothes the bidirectional metric received from the metric determining means 201A by the method described above (step S32), and the smoothed metric is updated by the updating means 241 and the message creating means. Output to 242.

  The message creation means 242 of each of the wireless devices 31 to 43 creates a Hello message including the metric received from the smoothing means 202 and advertises it at a constant period T1 (= 2 second period). Accordingly, the smoothed bidirectional metric is periodically advertised (step S33).

  Further, the updating unit 241 of each of the wireless devices 31 to 43 updates the routing table 21 with the metric received from the smoothing unit 202 (step S34).

  After that, when the communication unit 204 of each wireless device 31 to 43 receives data to be transmitted to the transmission destination from the message creation unit 242, the received data is stored in the data part to create a packet, and the created The route search means 203 is requested to search for a route for transmitting the packet to the transmission destination.

  In response to a request from the communication unit 204, the route search unit 203 of each wireless device 31 to 43 searches the route for transmitting the packet to the transmission destination with reference to the updated routing table 21 (step S35). ), And outputs the searched route to the communication means 204. And the communication means 204 of each radio | wireless apparatus 31-43 transmits a packet to a transmission destination along the path | route searched by the path | route search means 203 (step S36). As a result, the series of operations ends.

  In the above description, it has been described that the bidirectional metric is smoothed and then output to the updating unit 241 and the message creating unit 242. However, the present invention is not limited to this, and the bidirectional metric is smoothed. Instead, the data may be output to the updating unit 241 and the message creating unit 242.

  As described above, according to the fourth embodiment, each of the wireless devices 31 to 43 determines a bidirectional metric in the wireless link between itself and an adjacent wireless device, and routes the determined bidirectional metric. Therefore, the routing table 21 is created and updated using the same metric between the two adjacent wireless devices, so that isotonicity is guaranteed and the route becomes loop-free. The optimal solution for the route is guaranteed.

  Therefore, according to the present invention, the wireless network 100 can be stabilized.

  Others are the same as in the first embodiment.

[Embodiment 5]
FIG. 27 is a schematic block diagram showing the configuration of the wireless device 31 shown in FIG. 1 according to the fifth embodiment. The wireless device 31 shown in FIG. 1 includes the wireless device 31D shown in FIG. 27 in the fifth embodiment.

  The wireless device 31D is the same as the wireless device 31A except that the communication control unit 15A of the wireless device 31A illustrated in FIG. 15 is replaced with a communication control unit 15D.

  The communication control unit 15D is the same as the communication control unit 15A except that the IP module 20A of the communication control unit 15A shown in FIG. 15 is replaced with an IP module 20C.

  The IP module 20C determines the bidirectional metric of the wireless link formed between the wireless device 31D and the adjacent wireless device adjacent to the wireless device 31D by the method according to the fourth embodiment, and routes the determined bidirectional metric. Output to daemon 24A.

  FIG. 28 is a functional block diagram showing functions for executing bidirectional metric determination and metric update timing adjustment. The IP module 20C is the same as the IP module 20A except that the metric determination unit 201 of the IP module 20A shown in FIG. 16 is replaced with a metric determination unit 201A.

  The metric determination unit 201A determines a bidirectional metric using any one of the bidirectional metric determination methods 1 to 5 according to the fourth embodiment, and updates the determined bidirectional metric. The message is output to the message creation unit 242 and the transmission timing adjustment unit 243.

  The transmission timing adjustment unit 243 adjusts the transmission timing T_tx of the bidirectional metric based on the bidirectional metric received from the metric determination unit 201A, and the message generation unit 242 adjusts the transmission timing T_tx of the bidirectional metric. Output to.

  Then, the message creation unit 242 advertises a Hello message including a bidirectional metric at the transmission timing T_tx received from the transmission timing adjustment unit 243.

  Each of the wireless devices 32 to 43 has the same configuration as the wireless device 31D illustrated in FIGS.

  A radio apparatus 31D according to the fifth embodiment is a combination of the radio apparatus 31A according to the second embodiment and the radio apparatus 31C according to the fourth embodiment. Therefore, the radio apparatus 31D according to the fifth embodiment determines a bidirectional metric between two adjacent radio apparatuses, and advertises the determined bidirectional metric at a time interval equal to or longer than a normal Hello message transmission cycle. .

  As a result, isotonicity is guaranteed, the route becomes loop-free, and the number of updates of the routing table 21 decreases. Therefore, the wireless network 100 can be stabilized.

  FIG. 29 is a flowchart for explaining a communication method according to the fifth embodiment. When a series of operations is started, the metric determination unit 201A of each of the wireless devices 31 to 43 is based on the communication quality in both directions of the wireless link formed between each of the wireless devices 31 to 43 and the adjacent wireless device. Then, the bidirectional metric is determined by the above-described method (step S41), and the determined bidirectional metric is output to the updating unit 241, the message creating unit 242, and the transmission timing adjusting unit 243.

  The transmission timing adjustment unit 243 then sets the transmission interval of the bidirectional metric determined by the above-described method based on the bidirectional metric received from the metric determination unit 201A to be equal to or greater than the transmission interval of the normal Hello message. As described above, the transmission timing of the bidirectional metric is adjusted (step S42).

  Thereafter, the same steps S43 to S46 as steps S14 to S17 of the flowchart shown in FIG. 17 are executed. Thus, a series of operations is completed.

  The rest is the same as in the first and second embodiments.

[Embodiment 6]
FIG. 30 is a schematic block diagram showing the configuration of the wireless device 31 shown in FIG. 1 according to the sixth embodiment. The wireless device 31 shown in FIG. 1 includes the wireless device 31E shown in FIG. 30 in the sixth embodiment.

  The wireless device 31E is the same as the wireless device 31B except that the communication control unit 15B of the wireless device 31B shown in FIG. 19 is replaced with a communication control unit 15E.

  The communication control unit 15E is the same as the communication control unit 15B except that the IP module 20A of the communication control unit 15B shown in FIG. 19 is replaced with an IP module 20C.

  The IP module 20C performs the function described in the fifth embodiment.

  FIG. 31 is a functional block diagram showing a function for executing bidirectional metric determination and synchronization of update timing of the routing table 21.

  In the sixth embodiment, when the metric determination unit 201A determines a bidirectional metric by the above-described method, the metric determination unit 201A outputs the determined bidirectional metric to the update unit 241, the message creation unit 242 and the update timing synchronization unit 244. To do.

  When the update timing synchronization unit 244 receives the bidirectional metric from the metric determination unit 201A, the update timing synchronization unit 244 determines the update timing T_update by the above-described method based on the received bidirectional metric, and the determined update timing T_update is determined. Output to the updating means 241.

  FIG. 32 is a diagram for explaining another operation for updating the routing table 21 in synchronization between a plurality of wireless devices. The update timing synchronization unit 244 of the wireless device A determines the update timing T_update based on the bidirectional metric received from the metric determination unit 201A. Therefore, in the process of determining the update timing T_update, the metric AB_Metric and the metric A Hello message including BA_Metric and bidirectional metric Metric is created and advertised.

  Further, the update timing synchronization unit 244 of the wireless device B also creates and advertises a Hello message including the metric AB_Metric, the metric BA_Metric, and the bidirectional metric Metric for the same reason.

  Others are the same as the description in FIG.

  The updating unit 241 receives a bidirectional metric from the metric determining unit 201A. When the update unit 241 receives the update timing T_update from the update timing synchronization unit 244, the update unit 241 performs a route calculation by reflecting the bidirectional metric on the route in synchronization with the received update timing T_update, and updates the routing table 21. Update.

  Note that the wireless devices 32 to 43 also include the wireless device 31E shown in FIGS.

  FIG. 33 is a flowchart for illustrating a communication method according to the sixth embodiment. When a series of operations is started, the metric determination unit 201A of each of the wireless devices 31 to 43 is based on the communication quality in both directions of the wireless link formed between each of the wireless devices 31 to 43 and the adjacent wireless device. Then, the bidirectional metric is determined by the above-described method (step S51), and the determined bidirectional metric is output to the update unit 241, the message creation unit 242, and the update timing synchronization unit 244.

  Thereafter, the same steps S52 to S59 as the steps S23 to S30 shown in FIG. 22 are sequentially executed. In this case, the “metric” described in steps S23 to S30 may be read as “bidirectional metric”.

  As described above, according to the sixth embodiment, each of the wireless devices 31 to 43 determines the bidirectional metric of the wireless link formed with the adjacent wireless device, and the determined bidirectional metric is When the change occurs, the route calculation is performed in synchronization with the plurality of wireless devices, the changed bidirectional metric is reflected in the route, and the routing table 21 is updated.

  As a result, isotonicity is ensured in the wireless network 100, the route becomes loop-free, and the optimal solution of the route is guaranteed.

  Therefore, according to the present invention, the wireless network 100 can be stabilized.

  Others are the same as in the first, third, and fourth embodiments.

[Embodiment 7]
FIG. 34 is a schematic block diagram showing the configuration of the wireless device 31 shown in FIG. 1 according to the seventh embodiment. In the seventh embodiment, the radio apparatus 31 shown in FIG. 1 includes the radio apparatus 31F shown in FIG.

  The wireless device 31F is the same as the wireless device 31A except that the communication control unit 15A of the wireless device 31A shown in FIG. 15 is replaced with a communication control unit 15F. The communication control unit 15F is the same as the communication control unit 15A except that the routing daemon 24A of the communication control unit 15A shown in FIG. 15 is replaced with a routing daemon 24C.

With routing daemon 24C receives the metric _{m i} from the IP module 20A, and adjust the transmission timing T_tx to advertise the received metric _{m i} in wireless network 100, advertising metrics _{m i} at the transmission timing T_tx that the adjustment The route calculation is performed by reflecting the metric _mi in the route in synchronization with the plurality of wireless devices, and the routing table 21 is updated.

  FIG. 35 is a functional block diagram illustrating a function for executing adjustment of the update timing of the metric and synchronization of the update timing of the routing table 21. The routing daemon 24C is obtained by adding update timing synchronization means 244 to the routing daemon 24A shown in FIG. 16, and the rest is the same as the routing daemon 24A.

In the seventh embodiment, the metric determining means 201, the metric _{m i} the updating means 241 as determined by the method described above, the message creation unit 242, and outputs to the transmission timing adjustment unit 243 and the update timing synchronization unit 244.

Transmission timing adjusting unit 243, based on the metric _{m i} received from the metric determining means 201 adjusts the transmit timing T_tx by the above-described method, and outputs the transmission timing T_tx that the adjustment to the message creating means 242.

Then, the message creating means 242 receives the transmission timing T_tx from the transmission timing adjusting means 243, the metric _{m i} received from the metric determining means 201 advertises in synchronization with the transmission timing T_tx.

The update timing synchronization unit 244, based on the metric _{m i} received from the metric determining means 201, by the method described above performs synchronization update timing T_update, outputs the update timing T_update that its synchronization to the updating means 241 .

Then, the update unit 241 receives the update timing T_update that is synchronized from the update timing synchronization unit 244, a reflecting metrics _{m i} received from the metric determining means 201 in the path in synchronization with the update timing T_update with route calculation To update the routing table 21.

  Note that the wireless devices 32 to 43 also include the wireless device 31F shown in FIGS.

  FIG. 36 is a flowchart for illustrating a communication method according to the seventh embodiment. The flowchart shown in FIG. 36 includes a flowchart obtained by connecting Steps S11 to S14 shown in FIG. 17 and Steps S23 to S30 shown in FIG. And after step S11-step S14 are performed sequentially, step S23-step S30 are performed sequentially.

  According to the seventh embodiment, each of the radio apparatuses 31 to 43 determines a metric of a radio link formed between adjacent radio apparatuses, and the determined metric is a transmission interval that is equal to or greater than a normal Hello message transmission interval. When the metric changes, the plurality of wireless devices synchronize, the changed metric is reflected in the route, route calculation is performed, and the routing table 21 is updated.

  As a result, in the wireless network 100, the number of times of route switching is reduced, isotonicity is guaranteed, the route becomes loop-free, and the optimal solution of the route is guaranteed.

  Therefore, according to the present invention, the wireless network 100 can be stabilized.

  Others are the same as Embodiments 1-3.

[Embodiment 8]
FIG. 37 is a schematic block diagram showing the configuration of the wireless device 31 shown in FIG. 1 according to the eighth embodiment. In the eighth embodiment, the wireless device 31 shown in FIG. 1 includes the wireless device 31G shown in FIG.

  The wireless device 31G is the same as the wireless device 31F except that the communication control unit 15F of the wireless device 31F illustrated in FIG. 34 is replaced with a communication control unit 15G. The communication control unit 15F is the same as the communication control unit 15F except that the IP module 20A of the communication control unit 15F shown in FIG. 34 is replaced with an IP module 20B.

  The IP module 20B determines a bidirectional metric by the above-described method, and smoothes the determined bidirectional metric. Then, the IP module 20B outputs the bidirectional metric before smoothing and the bidirectional metric after smoothing to the routing daemon 24C.

  The routing daemon 24C adjusts the transmission timing T_tx of the bidirectional metric by the above-described method based on the bidirectional metric before smoothing, and synchronizes with the adjusted transmission timing T_tx, Advertise metrics.

  Further, the routing daemon 24C determines the update timing T_update for updating the routing table 21 synchronously among a plurality of wireless devices based on the bidirectional metric after smoothing, and updates the determined update. The routing table 21 is updated in synchronization with the timing T_update.

  FIG. 38 is a functional block diagram showing functions for executing bidirectional metric determination, metric smoothing, metric update timing adjustment, and routing table 21 update timing synchronization.

  The metric determination unit 201A determines a bidirectional metric by the above-described method, and outputs the determined bidirectional metric to the smoothing unit 202 and the transmission timing adjustment unit 243.

  The smoothing means 202 smoothes the bidirectional metric received from the metric determination means 201A, and outputs the smoothed bidirectional metric to the update means 241, the message creation means 242 and the update timing synchronization means 244.

  The transmission timing adjustment unit 243 adjusts the transmission timing T_tx by the above-described method based on the bidirectional metric before smoothing, and outputs the adjusted transmission timing T_tx to the message creation unit 242.

  Then, upon receiving the transmission timing T_tx from the transmission timing adjustment unit 243, the message creation unit 242 creates and advertises a Hello message including a smoothed bidirectional metric in synchronization with the received transmission timing T_tx. .

  Further, the update timing synchronization means 244 determines the update timing T_update for updating the routing table 21 in synchronization with a plurality of wireless devices by the above-described method based on the bidirectional metric after smoothing, The determined update timing T_update is output to the update means 241.

  When the update unit 241 receives the update timing T_update from the update timing synchronization unit 244, the update unit 241 performs the path calculation by reflecting the smoothed bidirectional metric on the path in synchronization with the received update timing T_update, The routing table 21 is updated.

  Note that the wireless devices 32 to 43 also include the wireless device 31G shown in FIGS.

  FIG. 39 is a flowchart for explaining a communication method according to the eighth embodiment. The flowchart shown in FIG. 39 is the same as the flowchart shown in FIG. 33 except that step S51 of the flowchart shown in FIG. 33 is replaced with steps S61 to S64.

  When a series of operations starts, each wireless device 31 to 43 determines a bidirectional metric by the above-described method based on the bidirectional communication quality of the wireless link formed with the adjacent wireless device. Then (step S61), the determined bidirectional metric is smoothed (step S62).

  Thereafter, the wireless devices 31 to 43 adjust the smoothed bidirectional metric transmission timing by the above-described method so that the determined bidirectional metric transmission interval is equal to or greater than the normal Hello message transmission interval. (Step S63).

  And each radio | wireless apparatus 31-43 advertises the bi-directional metric after smoothing with the adjusted transmission timing (step S64).

  Thereafter, the above-described steps S52 to S59 are sequentially executed, and a series of operations is completed.

  According to the eighth embodiment, each of the wireless devices 31 to 43 determines a bidirectional metric of a wireless link formed with an adjacent wireless device, smoothes the determined bidirectional metric, Advertise a smoothed bidirectional metric at a transmission interval that is equal to or greater than the normal Hello message transmission interval, and when the bidirectional metric changes, it synchronizes between multiple wireless devices and routes the changed bidirectional metric. Then, the route calculation is performed by reflecting the result, and the routing table 21 is updated.

  As a result, in the wireless network 100, the number of times of route switching is further reduced, isotonicity is ensured, the route becomes loop-free, and the optimum solution of the route is guaranteed.

  Therefore, according to the present invention, the wireless network 100 can be stabilized.

  Others are the same as Embodiments 1-4.

In the above description, it has been described that the metric _mi is determined using the formulas (1) and (2). However, the present invention is not limited to this, and the metric _mi is described in Non-Patent Document 2. It may be determined in the same manner as Airtime Link Metric, and in general, it may be determined in the same manner as any metric as long as it is a metric that guarantees isotonicity.

  In the present invention, transmission rate determining means 160 constitutes “communication quality determining means”.

  Further, the transmission rate determining unit 160 and the metric determining unit 201, or the transmission rate determining unit 160 and the metric determining unit 201A constitute a “determining unit”.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  The present invention is applied to a wireless device capable of stabilizing a wireless network. In addition, the present invention is applied to a wireless network including a wireless device capable of stabilizing the wireless network.

1 is a schematic diagram of a wireless network including a wireless device according to an embodiment of the present invention. FIG. 2 is a schematic block diagram illustrating a configuration of the wireless device illustrated in FIG. 1 in the first embodiment. It is a block diagram of a packet in the OLSR protocol. It is a block diagram of the routing table shown in FIG. It is the schematic which shows the structure of a neighbor list. It is a figure which shows the example of a neighbor list. It is a conceptual diagram of topology information. It is a figure for demonstrating the method to detect the data arrival condition in each radio | wireless area. FIG. 3 is a functional block diagram of transmission rate determination means included in the wireless interface module shown in FIG. 2. It is a figure which shows the structure of the relationship table shown in FIG. It is a figure which shows the relationship between a throughput and a transmission rate. It is a figure for demonstrating the method of determining a transmission rate. It is a functional block diagram which shows the function relevant to the smoothing of a metric. 3 is a flowchart for illustrating a communication method in the first embodiment. FIG. 3 is a schematic block diagram illustrating a configuration of a wireless device illustrated in FIG. 1 in a second embodiment. It is a functional block diagram which shows the function which adjusts the timing which updates a metric. 10 is a flowchart for illustrating a communication method in the second embodiment. It is a functional block diagram which shows the other function which adjusts the timing which updates a metric. FIG. 6 is a schematic block diagram showing a configuration of a wireless device shown in FIG. 1 in a third embodiment. It is a functional block diagram which shows the function which synchronizes the update timing which updates a routing table. It is a figure for demonstrating the operation | movement which updates a routing table synchronizing between several radio | wireless apparatuses. 10 is a flowchart for illustrating a communication method in the third embodiment. It is another functional block diagram which shows the function which synchronizes the update timing which updates a routing table. It is a schematic block diagram which shows the structure in Embodiment 4 of the radio | wireless apparatus shown in FIG. FIG. 6 is a functional block diagram for performing bi-directional metric determination and metric smoothing. 10 is a flowchart for illustrating a communication method in a fourth embodiment. FIG. 6 is a schematic block diagram showing a configuration of a wireless device shown in FIG. 1 according to a fifth embodiment. It is a functional block diagram which shows the function which performs the determination of a bidirectional | two-way metric, and adjustment of the update timing of a metric. 10 is a flowchart for illustrating a communication method according to a fifth embodiment. It is a schematic block diagram which shows the structure by Embodiment 6 of the radio | wireless apparatus shown in FIG. It is a functional block diagram which shows the function which performs the determination of a bidirectional | two-way metric, and the synchronization of the update timing of a routing table. It is a figure for demonstrating the other operation | movement which updates a routing table synchronizing between several radio | wireless apparatuses. 10 is a flowchart for illustrating a communication method in a sixth embodiment. FIG. 10 is a schematic block diagram showing a configuration of a wireless device shown in FIG. 1 in a seventh embodiment. It is a functional block diagram which shows the function which performs adjustment of the update timing of a metric, and the synchronization of the update timing of a routing table. 18 is a flowchart for illustrating a communication method in the seventh embodiment. FIG. 10 is a schematic block diagram showing a configuration of the wireless device shown in FIG. 1 in an eighth embodiment. It is a functional block diagram which shows the function which performs the determination of a bidirectional | two-way metric, the smoothing of a metric, adjustment of the update timing of a metric, and the update timing of a routing table. 20 is a flowchart for illustrating a communication method in an eighth embodiment.

Explanation of symbols

  11, 51 to 63 antenna, 12 input unit, 13 output unit, 14 user application, 15, 15A, 15B, 15C, 15D, 15E, 15F, 15G communication control unit, 16 wireless interface module, 17 MAC module, 18 buffer, 19 LLC module 20, 20A, 20B, 20C IP module, 21 routing table, 22 TCP module, 23 UDP module, 24, 24A, 24B, 24C routing daemon, 31-43, 31A, 31B, 31C, 31D, 31E, 31F, 31G wireless device, 100 wireless network, 160 transmission rate determination means, 161 transmission / reception means, 201, 201A metric determination means, 202 smoothing means, 203 route search means, 204 communicator , 241 updating means 242 message creating unit 243 transmission timing adjusting means, 244 update timing synchronization unit, 1601 rate determining means, 1602 relationship table.

Claims (20)

Smoothing means for smoothing a metric indicating a route evaluation of a wireless link formed between the wireless device and an adjacent wireless device adjacent to the wireless device;
Communication means for advertising the metric smoothed by the smoothing means;
A wireless device comprising route search means for searching for a route to a transmission destination using the smoothed metric.   The radio apparatus according to claim 1, wherein the smoothing unit smoothes the metric by calculating an average of n (n is an integer of 2 or more) measured.   The radio apparatus according to claim 1, wherein the smoothing unit smoothes the metric so that a change width of the metric becomes a threshold value or less. A first metric in a first radio link when transmitting a packet from the wireless device to the adjacent wireless device, and a second metric in a second wireless link when transmitting a packet from the adjacent wireless device to the wireless device And determining means for determining a bi-directional metric in a radio link between the wireless device and the adjacent wireless device based on the metric of
The radio apparatus according to any one of claims 1 to 3, wherein the smoothing unit smoothes the bidirectional metric determined by the determining unit. The determining means includes
Communication quality determining means for determining communication quality in the first radio link;
The first metric is determined in accordance with the determination of the communication quality by the communication quality determination means, and the first metric determined based on the determined first metric and the second metric transmitted from the adjacent wireless device The wireless apparatus according to claim 4, further comprising metric determination means for determining a bidirectional metric. The first control packet is advertised such that the transmission interval of the first control packet including the bidirectional metric determined by the determination means is equal to or longer than the transmission cycle of the second control packet used for exchanging route information. Transmission timing adjusting means for adjusting the transmission timing to be performed,
The wireless device according to claim 4 or 5, wherein the communication unit advertises the bidirectional metric at the transmission timing adjusted by the transmission timing adjustment unit.   The radio apparatus according to claim 6, wherein the transmission timing adjustment unit adjusts the transmission timing to a timing at which a change in the bidirectional metric becomes a threshold value or less. Update timing synchronization means for synchronizing the update timing between a plurality of wireless devices for updating the routing table for determining the route to the transmission destination by the bidirectional metric,
Updating means for updating the routing table using the bidirectional metric at the update timing synchronized by the update timing synchronization means;
The wireless device according to claim 6 or 7, wherein the route search unit determines a route to the transmission destination using the routing table updated by the update unit. Determining means for determining a metric indicating a path evaluation of a radio link formed between the radio apparatus and an adjacent radio apparatus adjacent to the radio apparatus;
The first control packet is advertised such that the transmission interval of the first control packet including the bidirectional metric determined by the determination means is equal to or longer than the transmission cycle of the second control packet used for exchanging route information. Transmission timing adjusting means for adjusting the transmission timing to be performed;
Communication means for advertising the metric at the transmission timing adjusted by the transmission timing adjustment means;
A wireless device comprising route search means for searching for a route to a transmission destination using the metric.   The radio apparatus according to claim 9, wherein the transmission timing adjustment unit adjusts the transmission timing to a timing at which a change in the metric becomes a threshold value or less. The determination means includes a first metric in a first radio link when transmitting a packet from the wireless device to the adjacent wireless device, and a second metric when transmitting a packet from the adjacent wireless device to the wireless device. Determining a bi-directional metric in the radio link between the radio device and the neighboring radio device based on a second metric in the radio link;
The communication means advertises the bidirectional metric at the transmission timing adjusted by the transmission timing adjustment means;
The wireless communication according to claim 9 or 10, wherein the route search means searches for a route to a transmission destination using the bidirectional metric. The determining means includes
Communication quality determining means for determining communication quality in the first radio link;
The first metric is determined in accordance with the determination of the communication quality by the communication quality determination means, and the first metric determined based on the determined first metric and the second metric transmitted from the adjacent wireless device The wireless device according to claim 11, further comprising metric determination means for determining a bidirectional metric. Smoothing means for smoothing the bidirectional metric,
The communication means advertises a bidirectional metric smoothed by the smoothing means at the transmission timing,
The wireless device according to claim 11 or 12, wherein the route search means searches for a route to a transmission destination using the smoothed bidirectional metric. An update timing synchronization unit that synchronizes update timings between a plurality of wireless devices for updating a routing table for determining a route to the transmission destination according to the bidirectional metric determined by the determination unit;
Updating means for updating the routing table using the bidirectional metric at the update timing synchronized by the update timing synchronization means;
The wireless device according to claim 11, wherein the route search unit searches for a route to a transmission destination using the routing table updated by the update unit. Determining means for determining a metric indicating a path evaluation of a radio link formed between the radio apparatus and an adjacent radio apparatus adjacent to the radio apparatus;
Update timing synchronization means for synchronizing the update timing between a plurality of wireless devices for updating the routing table for determining the route to the transmission destination according to the metric determined by the determination means;
Updating means for updating the routing table using the metric determined by the determining means at the update timing synchronized by the update timing synchronizing means;
A wireless device comprising: a route search unit that searches for a route to the transmission destination using the routing table updated by the update unit. The first control packet is advertised such that the transmission interval of the first control packet including the bidirectional metric determined by the determination means is equal to or longer than the transmission cycle of the second control packet used for exchanging route information. Transmission timing adjusting means for adjusting the transmission timing to be performed;
The wireless device according to claim 15, further comprising a communication unit that advertises the metric at a transmission timing adjusted by the transmission timing adjustment unit. The determination means includes a first metric in a first radio link when transmitting a packet from the wireless device to the adjacent wireless device, and a second metric when transmitting a packet from the adjacent wireless device to the wireless device. Determining a bi-directional metric in the radio link between the radio device and the neighboring radio device based on a second metric in the radio link;
The radio according to claim 15 or 16, wherein the updating unit updates the routing table using the bidirectional metric determined by the determining unit at the update timing synchronized by the update timing synchronizing unit. apparatus. The determining means includes
Communication quality determining means for determining communication quality in the first radio link;
The first metric is determined in accordance with the determination of the communication quality by the communication quality determination means, and the first metric determined based on the determined first metric and the second metric transmitted from the adjacent wireless device 18. The wireless device according to claim 17, further comprising metric determination means for determining a bidirectional metric. Smoothing means for smoothing the bidirectional metric,
The communication means advertises a bidirectional metric smoothed by the smoothing means at the transmission timing,
The wireless device according to claim 17 or 18, wherein the updating unit updates the routing table using the smoothed bidirectional metric.   A wireless network comprising the wireless device according to any one of claims 1 to 19.

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