JP2006081163A - Wireless device and wireless network system equipped with it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless network system which is autonomously built and obtains higher throughput. <P>SOLUTION: Each of a plurality of wireless devices constituting an ad hoc network holds a routine table 20. The routine table 20 comprises a destination address, a next hop address, a metric, the total number of metrics, and a sequence number SeqNum. The metric is the number of hop-up to the destination address. The total number of metrics is determined according to received signal strength as it becomes smaller when the received signal strength becomes relatively stronger, and it becomes larger when the received signal strength becomes relatively weaker. Each wireless device forms a routine table 20 in accordance with a FSR protocol, and transmits or relays data by determining a path so that the total number of metrics becomes small in wireless communication for a source address to the destination address. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wireless device and a wireless network system including the wireless device, and more particularly to a wireless device configuring an autonomous and instantaneously constructed ad hoc network system and a wireless network system 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.

  Such an ad hoc network is about to be applied to various fields such as a wireless communication network in a stricken area and streaming in ITS (Intelligent Transport Systems) inter-vehicle communication (Non-Patent Document 1).

  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 GSR (Global State Routing), FSR (Fish-eye State Routing), OLSR (Optimized Link). State Routing) and DSDV (Destination Sequential Distance Vector) 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, when data communication is performed from a transmission source to a transmission destination, a route is determined so that the number of hops from the transmission source to the transmission destination is as small as possible (Non-Patent Document 2).
Masahiro Watanabe “Wireless Ad Hoc Network”, Automobile Engineering Society Spring Meeting Humantronics Forum, pp 18-23, Yokohama, May 2003. Guangyu Pei, at al, “Fisheye state routing: a routing scheme for ad hoc wireless networks”, ICC2000. Commun., Volume 1, pp70-74, LA, June 2000.

  However, when performing multi-hop communication in an ad hoc network, there is a problem that as the number of hops increases, throughput decreases and delay time increases.

  FIG. 32 is a conceptual diagram of an ad hoc network. The ad hoc network 200 includes, for example, automobiles 201 to 206. In this case, the ad hoc network 200 is a network that performs wireless communication between automobiles.

  When wireless communication is performed at the carrier frequency f1 using the automobile 201 as a transmission source and the automobile 206 as a transmission destination, wireless communication between the automobiles is performed in time series. That is, first, the automobile 201 functions as a transmitter (Tx) and the automobile 202 functions as a receiver (Rx), and wireless communication is performed between the automobiles 201 and 202. Thereafter, the automobile 202 functions as a transmitter (Tx) and the automobile 203 functions as a receiver (Rx), and wireless communication is performed between the automobiles 202 and 203. Similarly, wireless communication is sequentially performed between the automobiles 203 and 204, between the automobiles 204 and 205, and between the automobiles 205 and 206. As a result, the automobile 201 transmits data and the like to the automobile 206 by wireless communication.

  Thus, in multi-hop communication, wireless communication between automobiles (between terminals) is performed in time series, and data and the like are transmitted from the automobile 201 to the automobile 206 for the following reason. FIG. 33 is a conceptual diagram of wireless communication between adjacent terminals. FIG. 34 is another conceptual diagram of wireless communication between adjacent terminals. 33 and 34 represent the communication range of each terminal device.

  Referring to FIG. 33, terminal device S1 transmits a transmission request RTS (Request To Send) to terminal device D1. Then, the terminal device D1 transmits a transmission permission CTS (Clear To Send) to the terminal device S1 in response to the transmission request RTS from the terminal device S1. In response to the transmission permission CTS from the terminal device D1, the terminal device S1 transmits data DATA to the terminal device D1, and when receiving the data DATA, the terminal device D1 transmits an acknowledgment ACK to the terminal device S1.

  In such wireless communication between the terminal device S1 and the terminal device D1, when the terminal device S1 transmits a transmission request RTS to the terminal device D1, the terminal device S3 receives the transmission request RTS. This is because the terminal device S3 exists within the communication range of the terminal device S1. When the terminal device D1 transmits a transmission permission CTS to the terminal device S1 in response to the transmission request RTS, the terminal device S2 receives the transmission permission CTS. This is because the terminal device S2 exists within the communication range of the terminal device D1.

  In this case, since wireless communication is performed between the terminal device S1 and the terminal device D1, the terminal device S2 cannot transmit to the terminal device D1, and the terminal device S3 cannot transmit to the end-to-end device S1. Since the communication range of the terminal device S2 is different from the communication range of the terminal device S3, the terminal devices S2 and S3 do not know the existence of the terminal devices S3 and S2, respectively. Accordingly, the terminal devices S2 and S3 cannot directly perform wireless communication with each other.

  Referring to FIG. 34, terminal device S1 performs wireless communication with terminal device D1 as described in FIG. In this case, when the terminal device S1 transmits the transmission request RTS to the terminal device D1, the terminal device S2 receives the transmission request RTS of the terminal device S1. This is because the terminal device S2 exists within the communication range of the terminal device S1. Then, even if the terminal device S2 attempts to perform wireless communication with the terminal device D2, the terminal device S2 cannot perform wireless communication with the terminal device D2. This is because when the terminal device S2 transmits the transmission request RTS to the terminal device D2, the terminal device S1 receives the transmission request RTS from the terminal device S2.

  As described above, in an ad hoc network, terminal devices that can perform wireless communication are limited, and wireless communication is performed in time series.

  FIG. 35 is a relationship diagram between the throughput and the number of hops. In FIG. 35, a curve k1 represents TCP communication, and a curve k2 represents UDP communication. As described above, in an ad hoc network, wireless communication between terminal devices is performed in time series, and wireless communication is performed between a transmission source and a transmission destination. Therefore, when the number of hops increases, TCP communication and UDP communication are performed. As the throughput decreases, the delay time increases.

  Therefore, in the conventional ad hoc network, the route from the transmission source to the transmission destination is determined so that the number of hops is as small as possible. As a result, even when the received signal strength between the terminal devices is weak on the determined route, wireless communication is performed via the route, thereby reducing the throughput.

  Accordingly, the present invention has been made to solve such a problem, and an object of the present invention is to provide a wireless network system that is autonomously constructed and can obtain higher throughput.

  Another object of the present invention is to provide a wireless device that constitutes a wireless network system that is autonomously constructed and that can obtain higher throughput.

  According to the present invention, a wireless device is a wireless device that is autonomously established and constitutes a wireless network that performs wireless communication between a transmission source and a transmission destination, and includes a route determination unit, a communication unit, Is provided. The route determining means determines a route having a relatively high degree of stability as a route for performing the wireless communication. The communication means performs wireless communication along the route determined by the route determination means.

  Preferably, the degree of stability is determined based on at least one factor arbitrarily selected from a plurality of factors each representing the quality of wireless communication.

  Preferably, the degree of stability is determined using at least one path stability index arbitrarily selected from a plurality of path stability indices obtained by converting a plurality of factors, respectively.

  Preferably, the degree of stability is determined based on two path stability indices arbitrarily selected from a plurality of path stability indices.

  Preferably, the plurality of factors are converted into a plurality of path stability indexes so that the path stability index changes exponentially as the factors change linearly.

  Preferably, the plurality of factors comprise received signal strength, frame error rate, packet error rate, signal-to-noise ratio, and bit error rate.

  Preferably, the route determination means further determines a route for performing wireless communication so that the number of relays to the transmission destination is reduced.

  Moreover, according to this invention, a radio network system is a radio network system provided with the radio | wireless apparatus of any one of Claims 1-7.

  Each wireless device constituting the wireless network system according to the present invention determines a route having a relatively high degree of stability as a route for performing wireless communication, and performs wireless communication along the determined route.

  More preferably, each wireless device determines a path with relatively high radio wave reception intensity as a path for performing wireless communication, and performs wireless communication along the determined path.

  More preferably, each wireless device determines a route with a relatively low communication error rate of wireless communication as a route for performing wireless communication, and performs wireless communication along the determined route.

  More preferably, each wireless device determines a route for performing wireless communication by giving priority to a route with relatively strong radio wave reception intensity, performs wireless communication along the determined route, When the route for wireless communication cannot be determined depending on the reception strength of the wireless communication, a route with a relatively low communication error rate of wireless communication is determined as a route for performing wireless communication, and wireless communication is performed along the determined route. Do.

  Therefore, according to the present invention, even if the number of wireless devices that relay wireless communication increases, wireless communication is performed stably, so that throughput can be improved. In addition, the error rate can be lowered.

  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 radio network system according to an embodiment of the present invention. The wireless network system 10 includes wireless devices 1 to 8. The wireless devices 1 to 8 are arranged in a wireless communication space and autonomously configure a network. When transmitting data from the wireless device 1 to the wireless device 3, the wireless devices 2, 5 to 8 relay the data from the wireless device 1 and deliver it to the wireless device 3.

  In this case, the wireless device 1 can perform wireless communication with the wireless device 3 via three different paths. That is, the wireless device 1 can perform wireless communication with the wireless device 3 via the wireless devices 2 and 7, and can perform wireless communication with the wireless device 3 via the wireless devices 2, 5, and 6. It is also possible to perform wireless communication with the wireless communication 3 via the wireless device 8.

  When wireless communication is performed via the wireless device 8, the number of hops is the smallest “2”, and when wireless communication is performed via the wireless devices 2 and 7, the number of hops is “3”. , 6, the number of hops is the largest, “4”.

  Accordingly, when a route for performing wireless communication via the wireless device 8 is selected, the number of hops is minimized to “2”. Therefore, generally, the throughput of wireless communication from the wireless device 1 to the wireless device 3 is increased. .

  However, when the received signal strength between the wireless device 1 and the wireless device 8 is weak, the throughput of wireless communication between the wireless device 1 and the wireless device 8 decreases, so if a route with a small number of hops is selected, The throughput is not high.

  Therefore, in the following, a method for establishing a route between a transmission source and a transmission destination so as to increase the throughput of wireless communication will be described.

  The FSR protocol is basically used as a protocol for establishing a path between the transmission source and the transmission destination. This FSR protocol is a table-driven routing protocol, and exchanges route information with a relatively close wireless device and exchanges route information with a distant wireless device. It is a protocol that reduces the traffic load by reducing.

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

  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 to other communication devices via the wireless communication space. Transmit to the wireless device.

  The input unit 12 receives a destination of a message and data input by an operator of the wireless device 1 and outputs the received message and destination to the e-mail application 14. The display unit 13 displays a message according to control from the e-mail application 14.

  The e-mail 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 wireless interface module 16, a MAC module 17, an LLC (Logical Link Control) module 18, an IP (Internet Protocol) module 19, a routing table 20, a TCP module 21, and a UDP module. 22, an SMTP (Simple Mail Transfer Protocol) module 23, and a routing daemon 24.

  The wireless interface module 16 belongs to the physical layer, performs modulation / demodulation of the transmission signal or reception signal, frequency conversion, and the like according to a predetermined rule, detects the received signal strength, and outputs it to the routing daemon 24.

  The MAC module 17 belongs to the MAC layer, executes a MAC protocol, and performs retransmission control of data (packets). The MAC module 17 detects that the link has been disconnected when the number of retransmissions of data (packets) exceeds a predetermined value, and notifies the routing daemon 24 that the link has been disconnected.

  The LLC module 18 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 19 belongs to the Internet layer and generates an IP packet. The IP packet includes an IP header and an IP data portion for storing a packet of a higher protocol. When the IP module 19 receives data from the TCP module 21, the IP module 19 stores the received data in the IP data portion and generates an IP packet. Then, the IP module 19 searches the routing table 20 according to the FSR protocol, which is a table-driven routing protocol, and determines whether the path for transmitting the generated IP packet is normal. The IP module 19 transmits the generated IP packet to the LLC module 18 when the path for transmitting data is normal.

  The routing table 20 belongs to the Internet layer and stores route information in association with each destination address, as will be described later.

  The TCP module 21 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 21 transmits the generated TCP packet to the IP module 19.

  The UDP module 22 belongs to the transport layer, broadcasts an Update packet created by the routing daemon 24, receives an Update packet broadcast from another wireless device, and outputs it to the routing daemon 24.

  The SMTP module 23 belongs to the process / application layer, and secures a full-duplex communication channel and exchanges messages based on data received from the e-mail application 14.

  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. In addition, the routing daemon 24 periodically exchanges route information with other wireless devices that are relatively close according to the FSR protocol, and based on the obtained route information and the received signal strength received from the wireless interface module 16, An optimum route is calculated by a method described later, and the routing table 20 is dynamically created in the Internet layer.

  Note that each of the wireless devices 2 to 9 illustrated in FIG. 1 has the same configuration as that of the wireless device 1 illustrated in FIG. 2.

  FIG. 3 is a configuration diagram of the IP header. The IP header includes a version, header length, service type, packet length, identification number, flag, fragment offset, lifetime, protocol, header checksum, source IP address, destination IP address, and options.

  FIG. 4 is a configuration diagram of the TCP header. The TCP header includes a transmission source port number, a transmission destination port number, a sequence number, an acknowledgment (ACK) number, a data offset, a reservation, a flag, a window size, a header checksum, and an argent pointer.

  The transmission source port number is a number that identifies an application that has output a TCP packet when a plurality of applications are operating on the transmission source wireless device. The transmission destination port number is a number that identifies an application that delivers a TCP packet when a plurality of applications are operating on the transmission destination wireless device.

  TCP communication is an end-to-end connection-oriented communication protocol. A TCP module 21 of a wireless device that requests a connection connection of TCP communication (hereinafter referred to as “TCP communication connection request device”) has a connection in which SYN (Synchronize Flag) is set in Code Bit in the TCP header when the connection is established. The first packet indicating the connection request is transmitted to the TCP module 21 of the terminal that accepts the TCP communication connection connection (hereinafter referred to as “TCP communication connection accepting device”). In response to this, the TCP module 21 of the TCP communication connection accepting apparatus receives the second packet indicating the connection request acceptance and connection completion of the connection in which SYN and ACK (acknowledgment response) are set in the Code Bit in the TCP header. Transmit to the TCP module 21 of the requesting device. Further, in response to this, the TCP module 21 of the TCP communication connection requesting device sends a third packet indicating the connection completion of the connection in which the Code Bit in the TCP header is set to ACK (acknowledgment response) to the TCP of the TCP communication connection receiving device. Transmit to module 21.

  The connection disconnection request can be made from either the TCP communication requesting device or the TCP communication receiving device. The TCP module 21 of the wireless device that requests disconnection of TCP communication (hereinafter referred to as “TCP communication disconnection request device”) has a connection in which the Code Bit in the TCP header is set to FIN (Finish Flag) when the connection is disconnected. The first packet indicating the disconnection request is transmitted to the wireless device that accepts the disconnection of the TCP communication (hereinafter referred to as “TCP communication disconnection accepting device”). In response to this, the TCP module 21 of the TCP communication disconnection accepting apparatus receives the second packet indicating acceptance of the disconnection request for the connection in which the Code Bit in the TCP header is set to ACK (acknowledgment response) and the Code Bit in the TCP header. A third packet indicating completion of disconnection of the connection set in FIN is transmitted to the TCP module 21 of the TCP communication disconnection requesting device. Further, in response to this, the TCP module 21 of the TCP communication disconnection requesting device transmits a fourth packet indicating the completion of disconnection of the connection in which the Code Bit in the TCP header is set to ACK (acknowledgment response) to the TCP communication disconnection receiving device TCP. Transmit to module 21.

  FIG. 5 is a diagram showing an example of the routing table 20 shown in FIG. The routing table 20 includes a transmission destination address, an address of the adjacent wireless device (NextHop address), a metric, and a total metric number of one. The destination address, NextHop address, metric, and total metric number 1 are associated with each other.

  The destination address represents the IP address of the destination wireless device. The NextHop address represents the IP address of the wireless device that hops next. The metric represents a route index indicating a route state between the transmission source wireless device and the transmission destination wireless device. The metric stores the number of hops from the transmission source wireless device to the transmission destination wireless device when the path between the transmission source wireless device and the transmission destination wireless device is normal. When the path between the device and the destination wireless device is abnormal, infinity (∞) is stored. The total metric number 1 stores a numerical value determined according to the received signal strength. The total metric number 1 stores a relatively large numerical value when the received signal strength is relatively weak, and stores a relatively small numerical value when the received signal strength is relatively strong. A method of converting the received signal strength to the total metric number 1 will be described later.

  In the example of the routing table 20 illustrated in FIG. 5, the first route is a route in which the wireless device that is the transmission source is the wireless device 1 and the wireless device that is the transmission destination is the wireless device 3. Is the wireless device 2 and the packet transmitted by the wireless device 1 has a metric “4”, indicating that the packet is relayed by the three wireless devices and reaches the wireless device 3. The total metric number 1 is “5”.

  The second route is a route in which the wireless device that is the transmission source is the wireless device 1 and the wireless device that is the transmission destination is the wireless device 3, and the wireless device that first relays the packet transmitted by the wireless device 1 is wireless. The packet transmitted by the wireless device 1 that is the device 8 has a metric of “2”, and therefore indicates that the packet is relayed by one wireless device and reaches the wireless device 3. The total metric number 1 is “16”.

  A method for converting the received signal strength received from another wireless device into the total metric number 1 will be described. Table 1 shows the relationship between signal strength and metric value.

  The “metric value” shown in Table 1 is different from the value stored in the metric of the routing table 20 and is a value determined according to the received signal strength RSSI as described below ( same as below.).

  When the signal strength is higher than −60 dB, the metric value is “1”, and when the signal strength is in the range of −60 dB to −65 dB, the metric value is “2” and the signal strength is −65 dB to −65 dB. When the range is up to 70 dB, the metric value is “4”, and when the signal strength is in the range from −70 dB to −75 dB, the metric value is “8” and the signal strength is weaker than −75 dB. The metric value is “16”.

  Therefore, when receiving the received signal strength from the wireless interface module 16, the routing daemon 24 detects the metric value corresponding to the received received signal strength with reference to Table 1, and transmits the detected metric value to the path information. The routing table 20 is created by adding to the total metric number 1 of the route through the wireless device.

  This will be specifically described. FIG. 6 is a conceptual diagram of a topology message, FIG. 7 is a conceptual diagram of a topology table, and FIG. 8 is a conceptual diagram of a topology created based on the topology message.

  In creating the routing table 20 using the FSR protocol, each of the wireless devices 1 to 8 periodically broadcasts a topology message. Each wireless device 1-8 broadcasts, for example, a topology message indicating a topology within 2 hops from itself every 5 seconds, and broadcasts a topology message indicating a topology of 3 hops or more from itself every 15 seconds.

  Each of the wireless devices 1 to 8 recognizes how the wireless devices 1 to 8 are arranged in the wireless network system 10 by transmitting and receiving such a topology message, and indicates a route for each transmission destination. A table 20 is created.

  The wireless device 1 receives the topology message TPMS1 (see FIG. 6A) from the wireless device 8 every 5 seconds, and receives the topology message TPMS2 (see FIG. 6B) every 5 seconds from the wireless device 2. The topology message TPMS3 (see FIG. 6C) is received from the wireless device 2 every 15 seconds.

  That is, the wireless device 1 receives the topology messages TPMS1 and TPMS2 in the local area close to itself relatively frequently, and receives the topology message TPMS3 in the area far from itself in a relatively long cycle.

  The topology message TPMS1 includes “Originator”, N [i] (i = 0, 1,...), And M [i].

  “Originator” represents a reference wireless device, N [i] represents a wireless device adjacent to “Originator”, and M [i] represents an overall metric between “Originator” and N [i]. Expression 1 is expressed.

  Therefore, in the first stage of the topology message TPMS1, “Originator” is the wireless device 8, “metric” is zero (= 0), and the wireless device adjacent to the wireless device 8 is the wireless device 1 (= N [0 ] = 1) and wireless device 3 (= N [1] = 3), the total metric number 1 (= M [0]) between the wireless device 8 and the wireless device 1 is “8”, and wireless A topology message in which the total metric number 1 (= M [1]) between the device 8 and the wireless device 3 is “8” is shown.

  The second and third tiers of the topology message TPMS1 are topology messages in which the radio devices 1 and 3 existing at the position of 1 hop (= metric = 1) from the radio device 8 are “Originator”. Consists of the same elements as the topology message in the stage.

  The topology message TPMS2 is a topology message related to the wireless devices 1, 4, 5, and 7 adjacent to the wireless device 2, and the wireless devices adjacent to the wireless devices 1, 4, 5, and 7 that are located one hop away from the wireless device 2. It consists of a topology message related to the device and a topology message related to the wireless device adjacent to the wireless devices 3 and 6 existing at a position of 2 hops from the wireless device 2.

  Further, the topology message TPMS3 is composed of a topology message related to a wireless device adjacent to the wireless device 3 existing at a position of 3 hops from the wireless device 2.

  Each of topology messages TPMS2 and TPMS3 includes the same elements as topology message TPMS1.

  The metric value M [i] included in the topology messages TPMS1 to TPMS3 detects the received signal strength RSSI of the topology message received by each wireless device 1 to 8 from another wireless device (= adjacent wireless device), The detected received signal strength RSSI is obtained by converting it into a metric value with reference to Table 1. Since the topology message includes the address of the transmission source, each of the wireless devices 1 to 8 can recognize from which wireless device each topology message has been received. Accordingly, each of the wireless devices 1 to 8 creates a topology table by assigning the obtained metric value M [i] to the path to the recognized wireless device, and broadcasts the created topology table as a topology message. To do.

  The routing daemon 24 of the wireless device 1 creates a topology table TPTBL (see FIG. 7) based on the received topology messages TPMS1 to TPMS3. The topology table TPTBL includes a topology message related to a wireless device adjacent to the wireless device 1, a topology message related to a wireless device adjacent to the wireless devices 2 and 8 existing at a position 1 hop (= metric = 1) from the wireless device 1, and a wireless message. A topology message relating to a wireless device adjacent to the wireless devices 4, 5, and 7 existing at a position of 2 hops (= metric = 2) from the device 1, and a position of 3 hops (= metric = 3) from the wireless device 1. It consists of topology messages related to wireless devices adjacent to the wireless devices 3 and 6.

  The routing daemon 24 of the wireless device 1 refers to the topology table TPTBL, and first, the wireless devices 2 and 8 existing at a position one hop away from the wireless device 1 and the wireless device 1 and each of the wireless devices 2 and 8 And the wireless devices 3, 4, 5, 7 adjacent to the wireless devices 2, 8 existing at a position one hop away from the wireless device 1, and the wireless devices 2, 8, The total metric number 1 between the wireless devices 3, 4, 5 and 7 is recognized. Then, by repeating this, the routing daemon 24 of the wireless device 1 recognizes the topology of the wireless devices 1 to 8 shown in FIG. 1 and the total metric number 1 between adjacent wireless devices, and between adjacent wireless devices. A topology in which the total metric number 1 is assigned to is created (see FIG. 8).

  Then, based on the created topology, the routing daemon 24 of the wireless device 1 creates a routing table 20 (see FIG. 5) consisting of routes with the wireless device 3 as a transmission destination. In this case, there are two routes that pass through the wireless device 2, but the route of the wireless device 1 -the wireless device 2 -the wireless device 7 -the wireless device 3 has a total metric number 1 of 2 + 2 + 4 = 8, and the wireless device 1 -Wireless device 2-Wireless device 5-Wireless device 6-Wireless device 3 Since the total metric number 1 is larger than 1 (= 2 + 1 + 1 + 1 = 5), the total metric number 1 is smaller. The route of the wireless device 5 -the wireless device 6 -the wireless device 3 is selected.

  As described above, the routing daemon 24 of the wireless device 1 creates the routing table 20 based on the topology messages TPMS1 to TPMS3 periodically broadcast from other wireless devices.

  Note that the routing daemon 24 of the wireless device 1 creates a routing table that includes not only routes having the wireless device 3 as a transmission destination but also routes having other wireless devices as transmission destinations.

  As described above, in the present invention, received signal strength RSSI in wireless communication between wireless devices is converted into a metric value, and the converted metric value is included in the route information as a route stability index indicating the degree of stability of the route. A table 20 is created. As shown in Table 1, when the received signal strength RSSI is relatively strong, the metric value is relatively small. When the received signal strength RSSI is relatively weak, the metric value is relatively growing. Therefore, a relatively small metric value means that the route is more stable, and a relatively large metric value means that the route is more unstable.

  When the received signal strength RSSI is converted into a metric value, the received signal strength RSSI is converted into a plurality of regions (region RGE1, stronger than −60 dB, region RGE2 from −60 dB to −65 dB, region RGE3 from −65 dB to −70 dB, −70 dB to As the received signal strength RSSI becomes weaker in the direction from the region RGE1 to the region RGE5, the metric value becomes larger by a power of 2 as the region RGE4 is weaker than the region RGE4 of −75 dB and the region RGE5 is weaker than −75 dB. That is, as the received signal strength RSSI decreases linearly, the metric value increases exponentially.

  Thus, by increasing the metric value as the path stability index exponentially as the received signal strength RSSI decreases linearly (that is, as the received signal strength RSSI increases linearly, By making the metric value exponentially small), paths with greater stability can be easily selected.

  That is, when the metric value is linearly increased as the received signal strength RSSI is linearly weakened, the difference in metric value due to the difference in the received signal strength RSSI is reduced. In the routing table 20, since the total metric number 1 (= added value of the metric value of each route) in the entire route from the wireless device 1 to the wireless device 3 is stored, the received signal strength RSSI varies. If a metric value whose value does not change greatly is used, a large difference does not occur in a plurality of total metrics 1 assigned to a plurality of paths from the transmission source to the transmission destination.

  On the other hand, when the metric value is increased exponentially as the received signal strength RSSI decreases linearly, the metric value changes greatly with respect to the change in the received signal strength RSSI, so the total metric number 1 also changes greatly. As a result, a large difference occurs in the number of total metrics 1 assigned to the plurality of paths from the transmission source to the transmission destination.

  Therefore, in the present invention, the metric value increases exponentially as the received signal strength RSSI decreases linearly.

  The other wireless devices 2 to 8 shown in FIG. 1 also create the routing table 20 in the same manner as the wireless device 1 described above.

  An operation of performing wireless communication between the transmission source (wireless device 1) and the transmission destination (wireless device 3) will be described. FIG. 9 is a flowchart in the first embodiment for describing an operation of performing wireless communication between a transmission source and a transmission destination. When a series of operations is started, the routing daemon 24 of the wireless device 1 that is the transmission source selects a more stable route and unicasts the data (step S1). Then, the repeater such as the wireless device 2 selects a more stable route and unicasts the data (step S2). Thereafter, the wireless device 3 that is the transmission destination receives data from the wireless device 1 (step S3).

  Thereby, transmission of data from the wireless device 1 to the wireless device 3 is completed.

  FIG. 10 is a flowchart for explaining detailed operations in steps S1 and S2 shown in FIG. When a series of operations is started, the routing daemon 24 of the wireless device 1 or the repeater (wireless device 2 or the like) refers to the routing table 20 and the total metric number 1 is the same as that of the transmission destination (wireless device 3). It is determined whether or not there are a plurality of routes (step S11).

  When a plurality of routes having the same total metric number 1 do not exist, the routing daemon 24 of the wireless device 1 or the repeater (wireless device 2 or the like) selects a route having the minimum total metric number 1 from the plurality of routes. The TCP module 21, the IP module 19, the LLC module 18, the MAC module 17, and the wireless interface module 16 transmit or relay data along the route selected by the routing daemon 24 (step S12).

  On the other hand, when it is determined in step S11 that there are a plurality of routes having the same total metric number 1, the routing daemon 24 of the wireless device 1 or the repeater (wireless device 2 or the like) sends the transmission destination (wireless device 3). It is determined whether there are a plurality of routes having the same hop number (step S13).

  When there are a plurality of routes having the same number of hops, the routing daemon 24 of the wireless device 1 or the repeater (such as the wireless device 2) selects one of the routes from the plurality of routes, and the TCP module 21, The IP module 19, the LLC module 18, the MAC module 17, and the wireless interface module 16 transmit or relay data along the route selected by the routing daemon 24 (step S14).

  On the other hand, when it is determined in step S13 that a plurality of routes having the same number of hops does not exist, the routing daemon 24 of the wireless device 1 or the repeater (wireless device 2 or the like) selects a plurality of routes having the smallest number of hops. The TCP module 21, the IP module 19, the LLC module 18, the MAC module 17, and the wireless interface module 16 select from the route, and transmit or relay data along the route selected by the routing daemon 24 (step S 15). A route with a small number of hops means a “route with a small number of relays” (hereinafter the same).

  Thereby, the detailed operation of steps S1 and S2 shown in FIG. 9 is completed.

  When the routing daemon 24 of the wireless device 1 transmits data according to the flowchart shown in FIG. 10, the routing daemon 24 refers to the routing table 20 shown in FIG. It is determined whether there are a plurality of paths having the same (see step S11).

  In this case, since there are not a plurality of routes having the same total metric number 1 for the wireless device 3 that is the transmission destination in the routing table 20, the routing daemon 24 of the wireless device 1 has the total metric number 1. The route that is the minimum is selected, and the TCP module 21, the IP module 19, the LLC module 18, the MAC module 17, and the wireless interface module 16 transmit data along the route selected by the routing daemon 24 (see step S12). .

  In the routing table 20, there are two total metric numbers 1 = “5” and “16”, and a route passing through the wireless device 2 and a route passing through the wireless device 8 exist.

  Then, the routing daemon 24 of the wireless device 1 has the total metric number 1 of the route passing through the wireless device 8 being “16” and the total metric number 1 of the route passing through the wireless device 2 is “5”. The route through the wireless device 2 having a smaller total metric number 1 is selected, and the TCP module 21, IP module 19, LLC module 18, MAC module 17, and wireless interface module 16 of the wireless device 1 are selected by the routing daemon 24. The data is transmitted to the wireless device 2 along the route.

  Next, a case where the wireless device 2 relays data from the wireless device 1 according to the flowchart shown in FIG. 10 will be described. FIG. 11 is another example of the routing table. The routing daemon 24 of the wireless device 2 creates the routing table 20A shown in FIG.

  When the routing daemon 24 of the wireless device 2 receives data from the wireless device 1, it detects that the received data is data to be transmitted to the wireless device 3. Then, the routing daemon 24 refers to the routing table 20A to determine whether or not there are a plurality of routes having the same total metric number 1 for the wireless device 3 that is the transmission destination (see step S11). . Since there are not a plurality of routes having the same total metric number 1 for the wireless device 3 in the routing table 20A, the routing daemon 24 of the wireless device 2 selects a route having the minimum total metric number 1, The TCP module 21, the IP module 19, the LLC module 18, the MAC module 17, and the wireless interface module 16 relay data along the route selected by the routing daemon 24 (see step S12).

  In the routing table 20A, there are a route through the wireless device 5 having a total metric number 1 of “4” and a route through the wireless device 7 having a total metric number 1 of “10” with respect to the wireless device 3. Therefore, the routing daemon 24 of the wireless device 2 selects a route through the wireless device 5 having a smaller total metric number 1, and the TCP module 21, the IP module 19, the LLC module 18, and the MAC module 17 of the wireless device 2 are selected. The wireless interface module 16 transmits data to the wireless device 5 along the route selected by the routing daemon 24.

  Similarly to the wireless device 2, the wireless device 6 also relays data received from the wireless device 2 to the wireless device 3.

  In the transmission of data by the wireless device 1 described above, the route via the wireless device 2 having the total metric number 1 of “5” is routed via the wireless device 8 having the total metric number 1 of “16”. Even though the number of hops is larger than that, the route via the wireless device 2 is selected. In the data relay by the wireless device 2, the route passing through the wireless device 5 having the total metric number 1 “4” is routed via the wireless device 7 having the total metric number 1 “10”. Even though the number of hops is larger than that, the route via the wireless device 5 is selected.

  As described above, in the present invention, if there are a plurality of paths having different total metrics 1, a path having a smaller total metrics 1 is selected regardless of the number of hops to the transmission destination.

  FIG. 12 shows still another example of the routing table. A case where the wireless device 2 holds the routing table 20B illustrated in FIG. In this case, since there are two paths having the same total metric number 1 with respect to the wireless device 3 that is the transmission destination, the routing daemon 24 of the wireless device 2 determines the total metric number 1 in step S11 shown in FIG. It is determined that there are a plurality of routes having the same hop count, and further, it is determined whether there are a plurality of routes having the same hop count with respect to the wireless device 3 that is the transmission destination (see step S13).

  In the routing table 20B, there are a route passing through the wireless device 7 having the hop number “2” and a route passing through the wireless device 5 having the hop number “3”. 24 selects a route through the wireless device 7 having a smaller number of hops, and the TCP module 21, the IP module 19, the LLC module 18, the MAC module 17, and the wireless interface module 16 follow the route selected by the routing daemon 24. The data is relayed along (see step S15).

  When a plurality of routes having the same total metric number 1 and different hop numbers exist in the routing table 20, the routing daemon 24 of the wireless device 2 selects a route having a smaller hop number, and The TCP module 21, the IP module 19, the LLC module 18, the MAC module 17, and the wireless interface module 16 relay data along the route selected by the routing daemon 24.

  A case where the wireless apparatus 2 holds the routing table 20C illustrated in FIG. In this case, since there are two routes having the same total metric number 1 and the same hop number for the wireless device 3 that is the transmission destination, the routing table 24 of the wireless device 2 has the total metric number 1 in step S11. It is determined that there are a plurality of routes having the same hop count, and it is further determined in step S13 that there are a plurality of routes having the same hop count.

  Then, the routing daemon 24 of the wireless device 2 selects one of the route passing through the wireless device 5 and the route passing through the wireless device 7, and the TCP module 21 and the IP module 19 of the wireless device 2 are selected. The LLC module 18, the MAC module 17, and the wireless interface module 16 relay the data along the route selected by the routing daemon 24 (see step S14).

  When a plurality of routes having the same total metric number 1 and the same hop number exist in the routing table 20, the routing daemon 24 of the wireless device 2 selects one of the routes, and the TCP module 21 and the IP module of the wireless device 2. 19, LLC module 18, MAC module 17 and wireless interface module 16 relay data along the path selected by routing daemon 24.

  As described above, the present invention determines a route for transmitting or relaying data based on the total metric number 1, and when the route cannot be determined based on the total metric number 1, the data is based on the number of hops to the destination. Determine the route to transmit or relay. That is, according to the present invention, a more stable route is determined as a route for transmitting or relaying data based on the degree of stability of the route. Determine a route to transmit or relay data.

  As a result, data can be transmitted to a transmission destination via a stable path, and as a result, throughput when data is transmitted can be improved. In the conventional ad hoc network, when the number of hops to the transmission destination increases, the throughput decreases with the increase in the number of hops. Since the data is transmitted to the transmission destination via a path having a smaller value, that is, a higher degree of stability, the throughput can be improved even if the number of hops increases. That is, since a route with a higher degree of stability is selected and data is transmitted or relayed, the occurrence of data retransmission between wireless devices is extremely low, and the throughput can be improved.

  In the following, experimental results when routing is performed according to the protocol according to the present invention will be described. FIG. 13 is a schematic diagram showing a layout of an experiment. In the experiment, a transmitter device S, a receiver device D, and a repeater device W, X, Y, and a wireless device S are placed in a substantially square-shaped space 50 surrounded by an inner wall made of a metal sealed partition. This was done with Z installed.

  Each of the wireless terminals S, D, W, X, Y, and Z was equipped with an 802.11b wireless LAN card. Further, specific arrangement positions of the wireless terminals S, D, W, X, Y, and Z are as shown in FIG. That is, the wireless terminals S, D, W, X, Y, and Z are arranged in the space 50 so that two routes are formed. The two routes are set so that the number of hops and the received signal strength are different.

  FIG. 14 is a timing chart of the total metric number 1 when the conventional FSR protocol is used in the layout shown in FIG. 14A shows TCP mode communication, and FIG. 14B shows UDP mode communication. When the conventional FSR protocol is used, the total metric number 1 corresponds to the conventional hop number.

  In the case of TCP mode communication, the total metric number 1 is “1” or “2”. And 98.2% is 2 hops. The breakdown is 60.8% for the relay of the wireless device X, 37.4% for the relay of the wireless device Z, and 1.8% for the one-hop direct communication ((a) in FIG. 14). reference).

  In the UDP mode communication, the total metric number 1 is “2” or “3”. And 95.4% is 2 hops and 4.6% is 3 hops (see FIG. 14B).

  Thus, when the conventional FSR protocol is used, two-hop wireless communication via the wireless terminal X is dominant in both TCP mode communication and UDP mode communication. This is because the conventional FSR protocol determines a route so that the number of hops is minimized.

  FIG. 15 is a timing chart of the total metric number 1 when the protocol according to the present invention is used in the layout shown in FIG. FIG. 15A shows TCP mode communication, and FIG. 15B shows UDP mode communication. In FIGS. 15A and 15B, the protocol according to the present invention is represented as “FSR-MS”.

  In the case of TCP mode communication, the total metric number 1 is in the range of 5 to 19 (see FIG. 15A). And 96.0% was 4 hops, 4.0% was 3 hops or 2 hops, and direct communication of 1 hop was not observed.

  In the case of UDP mode communication, the total metric number 1 is in the range of 5 to 24 (see FIG. 15B). And 84.7% were 4 hops, 15.3% were 3 hops or 2 hops, and direct communication of 1 hop was not observed.

  The total metric number 1 has a smaller fluctuation range in the TCP mode.

  In this way, by routing using the total metric number 1 that reflects the received signal strength, the route with the larger number of hops (wireless device S → wireless device Y → wireless device Z → wireless device W → wireless device D). It has been confirmed that there is a high probability that the route is selected.

  FIG. 16 is a timing chart of the total metric number 1 when the power of the wireless device on the route with the larger number of hops is turned off in the layout shown in FIG. FIG. 16A shows TCP mode communication, and FIG. 16B shows UDP mode communication.

  In both the TCP mode communication and the UDP mode communication, the total metric number 1 exists in a range of approximately 9 to 24, and there is a high probability that the total metric number 1 is higher than “20”. And this numerical value is larger than the numerical value shown to (a) and (b) of FIG.

  When the protocol according to the present invention is used (FSR-MS), a route with a smaller total metric number 1 is selected. Therefore, the experimental result shown in FIG. This is to support that a path with a smaller (S) is selected (wireless device S → wireless device Y → wireless device Z → wireless device W → wireless device D).

  FIG. 17 is a diagram showing the relationship between the throughput and error rate and the received signal strength. The throughput and error rate shown in FIG. 17 are the results of measuring the throughput and error rate in the TCP mode and UDP mode at that time by setting the received signal strength by changing the distance between the wireless devices.

  17, in the layout shown in FIG. 13, a 2-hop route (wireless device S → wireless device X → wireless device D) and a 4-hop route (wireless device S → wireless device Y → wireless device Z → wireless device W → The average value of the received signal strength between the wireless devices D) and each wireless device is indicated by a dotted line. The 2-hop route is in a region where the received signal strength between wireless devices is lower than the 4-hop route, and a decrease in transmission speed and an increase in error rate are observed. As described above, it was found that in the region where the average value of the received signal strength is low, the throughput is lowered and the error rate is increased even if the number of hops is small. On the other hand, it was found that the 4-hop route is in a region where the average value of the received signal strength is strong, and even if the number of hops increases, the throughput improves and the error rate decreases.

  Therefore, the protocol according to the present invention can improve the wireless communication throughput and reduce the error rate even if the number of hops is increased by selecting a route based on the received signal strength.

  FIG. 18 is a relationship diagram between throughput and frequency in the TCP mode. FIG. 19 is a relationship diagram between throughput and frequency in the UDP mode. As understood from the results of FIGS. 18 and 19, in both the TCP mode and the UDP mode, the throughput is higher when the protocol (FSR-MS) according to the present invention is used than when the conventional FSR protocol is used. I understand.

  FIG. 20 is a relationship diagram between delay time and frequency. FIG. 20A shows the first measurement result, and FIG. 20B shows the second measurement result. In the first measurement, the delay time is shorter when the FSR protocol is used. However, in the second measurement, when the FSR protocol was used, the short delay time observed in the first measurement was hardly observed. On the other hand, when the protocol (FSR-MS) according to the present invention was used, the delay time was observed as in the first measurement.

  Therefore, it was found that stable wireless communication can be performed by using the protocol (FSR-MS) according to the present invention.

  From the above results, it is possible to improve the throughput and determine the error rate by determining the route with stronger received signal strength as the route for wireless communication than determining the route with the smaller number of hops as the route for wireless communication. It has been demonstrated that stable wireless communication is possible.

  In the above description, the path for wireless communication is determined so that the received signal strength becomes stronger. However, the present invention is not limited to this, and a transmission request RTS is transmitted and a transmission permission CTS is returned. The route for wireless communication may be determined so that the probability is high, or the route for wireless communication may be determined so that the probability that data is transmitted and an acknowledgment ACK is returned is high. In other words, the present invention only needs to determine a more stable route as a route for performing wireless communication and perform wireless communication along the determined route.

  In the above, the received signal strength RSSI is converted into the total metric number 1 so that the total metric number 1 increases exponentially when the received signal strength RRSI becomes linearly weak. Not limited to this, the received signal strength RSSI may be converted into the total metric number 1 so that the total metric number 1 increases exponentially when the received signal strength RRSI increases linearly. In this case, it means that a route having a large total metric number 1 is a more stable route.

  Further, in the present invention, the received signal strength RSSI is converted into the total metric number 1 so that the total metric number 1 increases exponentially as the received signal strength RSSI decreases linearly, and the changed total metric number. By determining the route with smaller 1 as the route for wireless communication, the protocol according to the present invention can be executed according to the procedure of the conventional FSR protocol. That is, in the conventional FSR protocol, a route for performing wireless communication is determined so that the number of hops to the transmission destination is reduced, but the protocol according to the present invention performs wireless communication so that the total metric number 1 is reduced. What is necessary is just to determine the path | route for performing. When the total metric number 1 is the same, a route for performing wireless communication may be determined so that the number of hops to the transmission destination is reduced.

  Furthermore, in the above description, the table-driven protocol has been described. However, the present invention is not limited to this, and can be applied to an on-demand protocol and a protocol in which the table-driven and on-demand protocols are mixed.

  In the present invention, the total metric number 1 constitutes a “path stability index”.

  Table 1 constitutes a “map”.

  Further, the received signal strength RSSI constitutes a “factor” representing the quality of wireless communication.

  Furthermore, the routing daemon 24 that determines a more stable route based on the routing table 20 constitutes a “route determination unit”.

  Further, the TCP module 21, the IP module 19, the LLC module 18, the MAC module 17, and the wireless interface module 16 that transmit or relay data along the route determined by the routing daemon 24 constitute “communication means”.

[Embodiment 2]
FIG. 21 is a schematic block diagram in the second embodiment showing the configuration of radio apparatus 1 shown in FIG. The wireless device 1A according to the second embodiment is the same as the wireless device 1 except that the communication control unit 15 of the wireless device 1 shown in FIG.

  The communication control unit 15A converts the wireless interface module 16, the MAC module 17, the routing table 20 and the routing daemon 24 of the communication control unit 15 shown in FIG. 2 into the wireless interface module 16A, the MAC module 17A, the routing table 30 and the routing daemon 24A, respectively. Instead, a timer 25 is added, and the rest is the same as the communication control unit 15.

  The wireless interface module 16A performs functions other than the function of detecting the received signal strength RSSI and outputting it to the routing daemon 24 among the functions of the wireless interface module 16 shown in FIG.

  The MAC module 17A calculates a frame error rate (FER: Frame Error Ratio) by a method described later, and outputs the calculated frame error rate FER to the routing daemon 24A. The MAC module 17A performs the same functions as the MAC module 17 in addition.

  The routing daemon 24A dynamically creates the routing table 30 by calculating an optimum route based on the route information acquired from other wireless devices and the frame error rate FER received from the MAC module 17A by a method described later. The routing daemon 24A performs the same functions as the routing daemon 24.

  The timer 25 belongs to the MAC layer, measures time according to an instruction from the MAC module 17A, and outputs the measured time to the MAC module 17A according to a request from the MAC module 17A.

  Similar to the routing table 20, the routing table 30 stores route information in association with each transmission destination.

  In the second embodiment, each of radio apparatuses 2 to 8 has the same configuration as radio apparatus 1A shown in FIG.

  FIG. 22 is a conceptual diagram for explaining a method of calculating the frame error rate FER. The wireless device A transmits the communication request packet RTS to the wireless device B at the timing t1, sets a fixed time CTS_timer simultaneously with the transmission of the communication request packet RTS, and increments the communication count TransmitCnt by “1”. Then, the wireless device B receives the communication request packet RTS from the wireless device A at timing t2, and transmits a communication permission packet CTS for the communication request packet RTS to the wireless device A at timing t3. Then, the wireless device A receives the communication permission packet CTS from the wireless device B at timing t4.

  When the wireless device A receives the communication permission packet CTS from the wireless device B within the predetermined time CTS_timer, the wireless device A does not count the communication error number FailCnt and does not receive the communication permission packet CTS from the wireless device B within the predetermined time CTS_timer. In this case, the number of communication errors FailCnt is incremented by “1”.

  When the wireless device A receives the communication permission packet CTS from the wireless device B within the predetermined time CTS_timer, the wireless device A transmits the data DATA to the wireless device B at the timing t5 and sets the fixed time ACK_timer simultaneously with the transmission of the data DATA. In addition, the transmission count TransmitCnt is incremented by “1”. Then, the wireless device B receives the data DATA from the wireless device A at timing t6 and transmits an acknowledgment packet ACK for the data DATA to the wireless device A at timing t7. Then, the wireless device A receives the acknowledgment packet ACK from the wireless device B at timing t8.

  When the wireless device A receives the acknowledgment packet ACK from the wireless device B within the ACK_timer for a certain time, the wireless device A does not count the communication error number FailCnt and does not receive the acknowledgment packet ACK from the wireless device B within the ACK_timer for the certain time. In this case, the number of communication errors FailCnt is incremented by “1”.

  When the wireless device A does not receive the communication permission packet CTS from the wireless device B within the predetermined time period CTS_timer, the wireless device A starts again from the transmission of the communication request packet RTS, and counts the communication count TransmitCnt and the communication error count FailCnt.

  The wireless device A repeatedly receives the CTS packet for the communication request packet RTS and the acknowledgment packet ACK for the data DATA for a predetermined number of times. When the communication number TransmitCnt reaches the predetermined number, the frame error rate FER is calculated by the following equation. Calculate.

FER = FailCnt / TransmitCnt (1)
Each of the wireless devices 1 to 8 counts the communication count TransmitCnt and the communication error number FailCnt by the same operation as the wireless device A, and uses the counted communication count TransmitCnt and communication error number FailCnt to calculate the frame error rate by the equation (1). Calculate FER.

  In this case, the MAC module 17A of each of the wireless devices 1 to 8 controls the timer 25 so as to measure the time simultaneously with the transmission of the communication request packet RTS or the data DATA, and indicates that the fixed time CTS_timer or ACK_timer has elapsed. The timer 25 is controlled to output the signal TimeExpire. When the MAC module 17A receives the signal TimeExpire from the timer 25, the MAC module 17A detects that the CTS_timer or ACK_timer has elapsed for a certain time.

  FIG. 23 is a diagram showing an example of the routing table 30 shown in FIG. The routing table 30 is the same as the routing table 20 except that “total metric number 1” in the routing table 20 shown in FIG.

  The destination address, the NextHop address, the metric, and the total metric number 2 are associated with each other.

  The total metric number 2 stores a numerical value determined according to the frame error rate FER. The total metric number 2 stores a relatively small numerical value when the frame error rate FER is relatively low, and stores a relatively large numerical value when the frame error rate FER is relatively high.

  In the example of the routing table 30 shown in FIG. 23, the first route is a route in which the wireless device as the transmission source is the wireless device 1 and the wireless device as the transmission destination is the wireless device 3, and the packet transmitted by the wireless device 1 is transmitted. Is the wireless device 2 and the packet transmitted by the wireless device 1 has a metric “4”, indicating that the packet is relayed by the three wireless devices and reaches the wireless device 3. The total metric number 2 is “6”.

  The second route is a route in which the wireless device that is the transmission source is the wireless device 1 and the wireless device that is the transmission destination is the wireless device 3, and the wireless device that first relays the packet transmitted by the wireless device 1 is wireless. The packet transmitted by the wireless device 1 that is the device 8 has a metric of “2”, and therefore indicates that the packet is relayed by one wireless device and reaches the wireless device 3. The total metric number 2 is “12”.

  A method for converting the frame error rate FER into the total metric number 2 will be described. Table 2 shows the relationship between the frame error rate FER and the metric value.

  The “metric value” shown in Table 2 is also different from the value stored in the metric of the routing table 30, and is a value determined according to the frame error rate FER as described below ( same as below.).

  When the frame error rate FER is lower than 0.1, the metric value is “1”, and when the frame error rate FER is in the range of 0.1 ≦ FER <0.2, the metric value is “2”. When the frame error rate FER is in the range of 0.2 ≦ FER <0.3, the metric value is “3”, and when the frame error rate FER is in the range of 0.3 ≦ FER <0.4, When the metric value is “4” and the frame error rate FER is in the range of 0.4 ≦ FER <0.5, the metric value is “5” and when the frame error rate FER is 0.5 or more. The metric value is “6”.

  Therefore, when receiving the frame error rate FER from the MAC module 17A, the routing daemon 24A detects a metric value corresponding to the received frame error rate FER with reference to Table 2, and detects the detected metric value as route information. The routing table 30 is created by adding to the total metric number 2 of the route through the transmitted wireless device.

  The method of creating the routing table 30 is the same as the method of creating the routing table 20 (see FIG. 5) in the first embodiment, and M [i] included in the topology message is determined based on the frame error rate FER. The only difference is that

  As described above, in the second embodiment of the present invention, the frame error rate FER in wireless communication between wireless devices is converted into a metric value, and the converted metric value is used as a route stability index indicating the degree of stability of the route. And the routing table 30 is created. As shown in Table 2, if the frame error rate FER is relatively low, the metric value is relatively small, and if the frame error rate FER is relatively high, the metric value is relatively growing. Therefore, even when the metric value is determined based on the frame error rate FER, a relatively small metric value means that the path is more stable, and a relatively large metric value means that It means that the route is more unstable.

  The other wireless devices 2 to 8 also create the routing table 30 in the same manner as the wireless device 1 described above based on the frame error rate FER.

  In the second embodiment, the operation of performing wireless communication between the transmission source (wireless device 1) and the transmission destination (wireless device 3) is performed according to the flowcharts shown in FIGS. 9 and 10 in the first embodiment. In this case, “total metric number 1” in steps S11 and S12 in the flowchart shown in FIG.

  As described above, even when the total metric number 2 determined based on the frame error rate FER is used, a route for transmitting or relaying data is determined based on the total metric number 2, and the route is determined based on the total metric number 2. When it cannot be determined, a route for transmitting or relaying data is determined based on the number of hops to the destination. That is, according to the present invention, a more stable route is determined as a route for transmitting or relaying data based on the degree of stability of the route represented by the total metric number 2, and when the route cannot be determined by the degree of route stability, the transmission is performed. Based on the number of previous hops, a route for transmitting or relaying data is determined.

  As a result, even when the frame error rate FER is used, data can be transmitted to the transmission destination via a stable path, and as a result, throughput when data is transmitted can be improved.

  In the above description, the frame error rate FER is converted into a metric value according to Table 2. However, the present invention is not limited to this, and the frame error rate FER is converted into a metric value according to Table 3. May be.

  The “metric value” shown in Table 3 is also different from the value stored in the metric of the routing table 30 and is a value determined according to the frame error rate FER as described below ( same as below.).

  When the frame error rate FER is lower than 0.1, the metric value is “1”, and when the frame error rate FER is in the range of 0.1 ≦ FER <0.2, the metric value is “2”. When the frame error rate FER is in the range of 0.2 ≦ FER <0.3, the metric value is “4”, and when the frame error rate FER is in the range of 0.3 ≦ FER <0.4, When the metric value is “8” and the frame error rate FER is in the range of 0.4 ≦ FER <0.5, the metric value is “16” and when the frame error rate FER is 0.5 or more. The metric value is “32”.

  Therefore, according to Table 3, the metric value increases by a power of 2 as the frame error rate FER increases linearly. That is, as the frame error rate FER increases linearly, the metric value increases exponentially.

  Thus, by increasing the metric value as the path stability index exponentially as the frame error rate FER increases linearly (that is, as the frame error rate FER decreases linearly, By making the metric value exponentially small), paths with greater stability can be easily selected.

  That is, when the metric value is increased linearly as the frame error rate FER increases linearly, the difference in metric value due to the difference in frame error rate FER decreases. In the routing table 30, since the total metric number 2 (= added value of the metric value of each route) in the entire route from the wireless device 1 to the wireless device 3 is stored, the frame error rate FER varies. If a metric value whose value does not change greatly is used, a large difference does not occur in the plurality of total metrics 2 assigned to the plurality of paths from the transmission source to the transmission destination.

  On the other hand, when the metric value is increased exponentially as the frame error rate FER increases linearly, the metric value changes greatly with respect to the change in the frame error rate FER, so the total metric number 2 also changes greatly. As a result, a large difference occurs in the plurality of total metrics 2 assigned to the plurality of paths from the transmission source to the transmission destination.

  Therefore, according to the present invention, the metric value increases exponentially as the frame error rate FER increases linearly.

  In the above description, it has been described that the frame error rate FER is calculated and the calculated frame error rate FER is converted into a metric value according to Table 2 or Table 3. However, the present invention is not limited thereto, and the frame error rate is not limited thereto. Instead of FER, any of packet error rate PER (Packet Error Ratio), signal-to-noise ratio SNR (Signal to Noise Ratio), signal power, bit error rate, carrier signal to noise ratio, and noise ratio including interference noise to signal May be used.

  The packet error rate PER is represented by a ratio of the number of packets in which a CRC (Cyclic Redundancy Check) error has occurred to the total number of packets transmitted and received. Therefore, the packet error rate PER is calculated by the MAC module 17A and transmitted to the routing daemon 24A by the MAC module 17A.

  The signal-to-noise ratio SNR is represented by the ratio of noise intensity to signal intensity. Accordingly, the signal-to-noise ratio SNR is calculated by the radio interface module 16A and transmitted to the routing daemon 24A by the radio interface module 16A.

  Furthermore, the signal power represents the power of the received signal. Accordingly, the signal power is detected by the radio interface module 16A and transmitted to the routing daemon 24A by the radio interface module 16A.

  Further, the bit error rate represents the error rate of the demodulated bits. Accordingly, the bit error rate is detected by the radio interface module 16A and transmitted to the routing daemon 24A by the radio interface module 16A.

  Further, the carrier signal to noise ratio represents the ratio of noise to the carrier signal. Accordingly, the carrier signal to noise ratio is detected by the radio interface module 16A and transmitted to the routing daemon 24A by the radio interface module 16A.

  Further, the noise ratio including interference noise to the signal represents [noise including interference noise] / signal intensity. Accordingly, a noise ratio including interference noise with respect to the signal is detected by the radio interface module 16A and transmitted to the routing daemon 24 by the radio interface module 16A.

  Each of the packet error rate PER, the signal-to-noise ratio SNR, the signal power, the bit error rate, the carrier signal-to-noise ratio, and the noise ratio including interference noise for the signal is converted into a metric value according to Table 2 or Table 3. The

  Others are the same as in the first embodiment.

  The total metric number 2 constitutes a “path stability index”. Table 2 or Table 3 constitutes a “map”.

  Further, each of the frame error rate FER, the packet error rate PER, the signal-to-noise ratio SNR, the bit error rate, the carrier signal-to-noise ratio, and the noise ratio including interference noise to the signal constitutes a “communication error rate” In the present invention, generally, the total metric number 2 is determined based on a metric value obtained by converting the communication error rate according to Table 2 or Table 3.

  Furthermore, each of the frame error rate FER, the packet error rate PER, the signal-to-noise ratio SNR, the bit error rate, the carrier signal-to-noise ratio, and the noise ratio including interference noise to the signal is a “factor” that represents the quality of the wireless communication. Configure.

  Furthermore, the routing daemon 24A that determines a more stable route based on the routing table 30 constitutes a “route determination unit”.

  Further, the TCP module 21, the IP module 19, the LLC module 18, the MAC module 17A, and the wireless interface module 16A that transmit or relay data along the route determined by the routing daemon 24A constitute “communication means”.

[Embodiment 3]
FIG. 24 is a schematic block diagram in the third embodiment showing the configuration of radio apparatus 1 shown in FIG. The wireless device 1B according to the third embodiment is the same as the wireless device 1 except that the communication control unit 15 of the wireless device 1 shown in FIG.

  The communication control unit 15B is obtained by replacing the MAC module 17, the routing table 20, and the routing daemon 24 of the communication control unit 15 shown in FIG. 2 with the MAC module 17A, the routing table 40, and the routing daemon 24B, respectively, and adding a timer 25. Others are the same as those of the communication control unit 15.

  The MAC module 17A and the timer 25 are as described in the second embodiment.

  The routing daemon 24B calculates an optimum route by a method described later based on the route information acquired from other wireless devices, the received signal strength RSSI received from the wireless interface module 16, and the frame error rate FER received from the MAC module 17A. Thus, the routing table 40 is dynamically created. The routing daemon 24B performs the same functions as the routing daemon 24.

  Similar to the routing table 20, the routing table 40 stores route information in association with each transmission destination.

  In the third embodiment, each of radio apparatuses 2 to 8 has the same configuration as radio apparatus 1B shown in FIG.

  FIG. 25 is a diagram showing an example of the routing table 40 shown in FIG. The routing table 40 is obtained by adding “total metric number 2” to the routing table 20 illustrated in FIG. 5, and is otherwise the same as the routing table 20.

  The destination address, the NextHop address, the metric, the total metric number 1, and the total metric number 2 are associated with each other.

  As described above, the total metric number 1 stores a numerical value determined by the received signal strength RSSI, and the total metric number 2 stores a numerical value determined according to the frame error rate FER as described above. .

  In the example of the routing table 40 illustrated in FIG. 25, the first route is a route in which the wireless device as the transmission source is the wireless device 1 and the wireless device as the transmission destination is the wireless device 3, and packets transmitted by the wireless device 1 are transmitted. Is the wireless device 2 and the packet transmitted by the wireless device 1 has a metric “4”, indicating that the packet is relayed by the three wireless devices and reaches the wireless device 3. The total metric number 1 is “4”, and the total metric number 2 is “6”.

  The second route is a route in which the wireless device that is the transmission source is the wireless device 1 and the wireless device that is the transmission destination is the wireless device 3, and the wireless device that first relays the packet transmitted by the wireless device 1 is wireless. The packet transmitted by the wireless device 1 that is the device 8 has a metric of “2”, and therefore indicates that the packet is relayed by one wireless device and reaches the wireless device 3. The total metric number 1 is “16” and the total metric number 2 is “12”.

  The method of creating the routing table 40 is the same as the method of creating the routing table 20 (see FIG. 5) in the first embodiment. The metric value M1 [i] determined based on the received signal strength RSSI, the frame The only difference is that it is created based on a topology message including a metric value M2 [i] determined based on the error rate FER.

  Accordingly, each of the wireless devices 1 to 8 is determined based on the wireless device N [i] adjacent to “Originator”, the metric value M1 [i] determined based on the received signal strength RSSI, and the frame error rate FER. A topology message with a set metric value M2 [i] as a set is created and broadcast. Each wireless device 1-8 that receives this topology message recognizes the topology of wireless devices 1-8 (see FIG. 8) according to the method described in the first embodiment, and two wireless devices between adjacent wireless devices. Recognize metric values M1 [i] and M2 [i]. Each of the wireless devices 1 to 8 calculates the total metric number 1 in each path to each transmission destination as the sum of the metric values M1 [i], and calculates the total metric number 2 in each path to each transmission destination as a metric value. The routing table 40 is created by calculating as the sum of M2 [i].

  As described above, in the third embodiment of the present invention, the received signal strength RSSI and the frame error rate FER in the wireless communication between the wireless devices are converted into metric values, and the converted metric values indicate the degree of stability of the route. The routing table 40 is created by including it in the route information as a stability index. As shown in Table 1, when the received signal strength RSSI is relatively strong, the metric value is relatively small. When the received signal strength RSSI is relatively weak, the metric value is relatively growing. Further, as shown in Table 2, when the frame error rate FER is relatively low, the metric value is relatively small, and when the frame error rate FER is relatively high, the metric value is relatively growing. Therefore, even when the metric value is determined based on the received signal strength RSSI and the frame error rate FER, a relatively small metric value means that the path is more stable, and the metric value is relatively Larger means that the path is more unstable.

  FIG. 26 is a flowchart in the third embodiment for explaining an operation of performing wireless communication between a transmission source and a transmission destination. When a series of operations is started, the routing daemon 24B of the wireless device 1 that is the transmission source selects the more stable path by giving priority to the total metric number 1 determined based on the received signal strength RSSI and performs data transmission. Is unicast (step S21). Then, the repeater such as the wireless device 2 gives priority to the total metric number 1 determined based on the received signal strength RSSI, selects a more stable path, and unicasts the data (step S22). Thereafter, the wireless device 3 that is the transmission destination receives data from the wireless device 1 (step S23).

  Thereby, transmission of data from the wireless device 1 to the wireless device 3 is completed.

  FIG. 27 is a flowchart for explaining detailed operations in steps S21 and S22 shown in FIG. When a series of operations is started, the routing daemon 24B of the wireless device 1 or the repeater (wireless device 2 or the like) refers to the routing table 40, and the total metric number 1 is the same as that of the transmission destination (wireless device 3). It is determined whether or not there are a plurality of routes (step S211).

  When a plurality of routes having the same total metric number 1 do not exist, the routing daemon 24B of the wireless device 1 or the repeater (wireless device 2 or the like) selects a route having the minimum total metric number 1 from the plurality of routes. The TCP module 21, the IP module 19, the LLC module 18, the MAC module 17A, and the wireless interface module 16 transmit or relay data along the path selected by the routing daemon 24B (step S212).

  On the other hand, when it is determined in step S211 that there are a plurality of routes having the same total metric number 1, the routing daemon 24B of the wireless device 1 or the repeater (wireless device 2 or the like) sends the transmission destination (wireless device 3). It is further determined whether or not there are a plurality of routes having the same total metric number 2. (Step S213).

  Then, when there are not a plurality of routes having the same total metric number 2, the routing daemon 24B of the wireless device 1 or the repeater (wireless device 2 or the like) selects a route having the minimum total metric number 2 from the plurality of routes. The TCP module 21, the IP module 19, the LLC module 18, the MAC module 17A, and the wireless interface module 16 of the wireless device 1 or the repeater (such as the wireless device 2) select the data along the route selected by the routing daemon 24B. Is transmitted or relayed (step S214).

  On the other hand, when it is determined in step S213 that a plurality of routes having the same total metric number 2 exist, the routing daemon 24B of the wireless device 1 or the repeater (wireless device 2 or the like) sends the transmission destination (wireless device 3). It is further determined whether or not there are a plurality of routes having the same hop count (step S215).

  When there are a plurality of routes having the same number of hops, the routing daemon 24B of the wireless device 1 or the repeater (wireless device 2 or the like) selects one of the routes from the plurality of routes, and the wireless device 1 or The TCP module 21, the IP module 19, the LLC module 18, the MAC module 17A, and the wireless interface module 16 of the repeater (such as the wireless device 2) transmit or relay data along the route selected by the routing daemon 24B (step). S216).

  On the other hand, when it is determined in step S215 that a plurality of routes having the same number of hops do not exist, the routing daemon 24B of the wireless device 1 or the repeater (wireless device 2 or the like) selects a plurality of routes having the smallest number of hops. The TCP module 21, the IP module 19, the LLC module 18, the MAC module 17A, and the wireless interface module 16 of the wireless device 1 or the repeater (wireless device 2, etc.) are selected from the route along the route selected by the routing daemon 24B. The data is transmitted or relayed (step S217).

  Thereby, the detailed operations of steps S21 and S22 shown in FIG. 26 are completed.

  When the routing daemon 24B of the wireless device 1 transmits data according to the flowchart shown in FIG. 27, the routing daemon 24B refers to the routing table 40 shown in FIG. It is determined whether there are a plurality of routes having the same number 1 (see step S211).

  In this case, since there are not a plurality of routes having the same total metric number 1 for the wireless device 3 as the transmission destination in the routing table 40, the routing daemon 24B of the wireless device 1 has the total metric number 1 The route that is the minimum is selected, and the TCP module 21, the IP module 19, the LLC module 18, the MAC module 17A, and the wireless interface module 16 of the wireless device 1 transmit data along the route selected by the routing daemon 24B ( (See step S212).

  In the routing table 40, there are two total metric numbers 1 = “4” and “16”, and a route passing through the wireless device 2 and a route passing through the wireless device 8 exist.

  Then, the routing daemon 24B of the wireless device 1 has the total metric number 1 of the route passing through the wireless device 8 being “16” and the total metric number 1 of the route passing through the wireless device 2 is “4”. The route through the wireless device 2 having a smaller total metric number 1 is selected, and the TCP module 21, the IP module 19, the LLC module 18, the MAC module 17A, and the wireless interface module 16 of the wireless device 1 are selected by the routing daemon 24B. The data is transmitted to the wireless device 2 along the route.

  Next, a case where the wireless device 2 relays data from the wireless device 1 according to the flowchart shown in FIG. 27 will be described. FIG. 28 is another example of the routing table 40 shown in FIG. The routing daemon 24B of the wireless device 2 creates a routing table 40A shown in FIG.

  When receiving the data from the wireless device 1, the routing daemon 24 </ b> B of the wireless device 2 detects that the received data is data to be transmitted to the wireless device 3. Then, the routing daemon 24B refers to the routing table 40A and determines whether or not there are a plurality of routes having the same total metric number 1 for the wireless device 3 that is the transmission destination (see step S211). . Since there are not a plurality of routes having the same total metric number 1 for the wireless device 3 in the routing table 40A, the routing daemon 24B of the wireless device 2 selects a route having the minimum total metric number 1, The TCP module 21, IP module 19, LLC module 18, MAC module 17A, and wireless interface module 16 of the wireless device 2 relay data along the route selected by the routing daemon 24B (see step S212).

  In the routing table 40A, a route that passes through the wireless device 5 whose total metric number 1 is “3” and a route that passes through the wireless device 7 whose total metric number 1 is “10” with respect to the wireless device 3 are shown. Therefore, the routing daemon 24B of the wireless device 2 selects a route via the wireless device 5 having a smaller total metric number 1, and the TCP module 21, the IP module 19, the LLC module 18, and the MAC module 17A of the wireless device 2 are selected. The wireless interface module 16 transmits data to the wireless device 5 along the route selected by the routing daemon 24B.

  Similarly to the wireless device 2, the wireless device 6 also relays data received from the wireless device 2 to the wireless device 3.

  In the data transmission by the wireless device 1 described above, the route passing through the wireless device 2 having the total metric number 1 of “4” is routed through the wireless device 8 having the total metric number 1 of “16”. Even though the number of hops is larger than that, the route via the wireless device 2 is selected. In the data relay by the wireless device 2, the route passing through the wireless device 5 having the total metric number 1 of “3” is routed via the wireless device 7 having the total metric number 1 of “10”. Even though the number of hops is larger than that, the route via the wireless device 5 is selected.

  Thus, in the present invention, if there are a plurality of routes having different total metrics 1, the route with the smaller total metrics 1 is preferentially selected regardless of the number of hops to the transmission destination.

  FIG. 29 shows still another example of the routing table 40 shown in FIG. A case will be described in which the wireless device 2 holds the routing table 40B illustrated in FIG. In this case, since there are two routes having the same total metric number 1 with respect to the wireless device 3 that is the transmission destination, the routing daemon 24B of the wireless device 2 determines the total metric number 1 in step S211 shown in FIG. It is determined that there are a plurality of routes having the same metric, and further, it is determined whether or not there are a plurality of routes having the same total metric number 2 for the wireless device 3 that is the transmission destination (see step S213).

  In the routing table 40B, there are a route passing through the wireless device 7 having the total metric number 2 of “8” and a route passing through the wireless device 5 having the total metric number 2 of “6”. The routing daemon 24B of No. 2 selects a route through the wireless device 5 having a smaller total metric number 2, and the TCP module 21, the IP module 19, the LLC module 18, the MAC module 17A, and the wireless interface module 16 of the wireless device 2 are selected. The data is relayed along the route selected by the routing daemon 24B (see step S214).

  When a plurality of routes having the same total metric number 1 and different total metric number 2 exist in the routing table 40, the routing daemon 24B of the wireless device 2 selects a route having a smaller total metric number 2, The TCP module 21, IP module 19, LLC module 18, MAC module 17A, and wireless interface module 16 of the wireless device 2 relay data along the route selected by the routing daemon 24B.

  A case will be described in which the wireless device 2 holds the routing table 40C illustrated in FIG. In this case, since there are two routes having the same total metric number 1 and total metric number 2 with respect to the wireless device 3 that is the transmission destination, the routing daemon 24B of the wireless device 2 determines in step S213 shown in FIG. Then, it is determined that there are a plurality of routes having the same total metric number 2, and it is further determined whether or not there are a plurality of routes having the same hop number with respect to the wireless device 3 that is the transmission destination (step). (See S15).

  In the routing table 40C, there are a route passing through the wireless device 7 having the hop number “2” and a route passing through the wireless device 5 having the hop number “3”. 24B selects a route through the wireless device 7 having a smaller number of hops, and the TCP module 21, IP module 19, LLC module 18, MAC module 17A, and wireless interface module 16 of the wireless device 2 are selected by the routing daemon 24B. The data is relayed along the route (see step S217).

  Thus, when the total metric number 1 and the total metric number 2 are the same and there are a plurality of routes having different hop numbers in the routing table 40, the routing daemon 24B of the wireless device 2 has a smaller number of hops. The route is selected, and the TCP module 21, the IP module 19, the LLC module 18, the MAC module 17A, and the wireless interface module 16 of the wireless device 2 relay the data along the route selected by the routing daemon 24B.

  A case where the wireless device 2 holds the routing table 20D shown in FIG. In this case, since there are two routes having the same total metric number 1, total metric number 2, and hop number for the wireless device 3 that is the transmission destination, the routing table 24B of the wireless device 2 is determined in step S211. In step S213, it is determined that there are a plurality of routes having the same total metric number 2, and in step S215, the number of hops is the same. It is determined that there are a plurality of routes.

  Then, the routing daemon 24B of the wireless device 2 selects one of a route passing through the wireless device 5 and a route passing through the wireless device 7, and the TCP module 21 and the IP module 19 of the wireless device 2 are selected. The LLC module 18, the MAC module 17A, and the wireless interface module 16 relay the data along the route selected by the routing daemon 24B (see step S216).

  As described above, when a plurality of routes having the same total metric number 1, the total metric number 2, and the hop number exist in the routing table 40, the routing daemon 24B of the wireless device 2 selects one of the routes, The TCP module 21, the IP module 19, the LLC module 18, the MAC module 17A, and the wireless interface module 16 of the device 2 relay data along the route selected by the routing daemon 24B.

  As described above, the invention according to the third embodiment determines a route for transmitting or relaying data based on the total metric number 1, and based on the total metric number 2 when the route cannot be determined based on the total metric number 1. The route for transmitting or relaying data is determined. Further, when the route cannot be determined by the total metric number 1 and the total metric number 2, the route for transmitting or relaying data is determined based on the number of hops to the destination. .

  That is, the invention according to the third embodiment selects a more stable path by giving priority to the total metric number 1 determined based on the received signal strength RSSI, and transmits or relays data through the selected more stable path. When it is determined as a route and the route cannot be determined depending on the degree of stability of the route, a route for transmitting or relaying data is determined based on the number of hops to the transmission destination.

  As a result, data can be transmitted to a transmission destination via a stable path, and as a result, throughput when data is transmitted can be improved. In particular, by determining more stable paths based on the total metric number 1 and the total metric number 2, even if there are multiple paths with the same received signal strength RSSI, the actual wireless communication status is reflected. Since a more stable route is determined based on the total metric number of 2, the more stable route can be determined more accurately.

  As described above, the more stable path is determined with priority given to the total metric number 1 determined based on the received signal strength RSSI for the following reason. The total metric number 2 is determined by a frame error rate that is a probability that the communication permission packet CTS or the acknowledgment packet ACK is not received from the wireless device of the transmission partner, and the communication permission packet CTS or the acknowledgment packet ACK is a radio wave between the wireless devices. Even if the situation is good, the transmission counterpart wireless device may not transmit from the transmission counterpart wireless device due to a packet collision, and the received signal strength RSSI is more routed than the frame error rate FER. This is because it is considered that the degree of stability is more accurately reflected.

  In the third embodiment, instead of the frame error rate FER, a packet error rate PER, a signal-to-noise ratio SNR, a signal power, a bit error rate, a carrier signal-to-noise ratio, and a noise ratio including interference noise for the signal The total metric number 2 may be determined using any of the above.

  In the above description, it has been described that a stable path is determined using the total metric number 1 determined based on the received signal strength RSSI and the total metric number 2 determined based on the frame error rate. In the present invention, not limited to this, the received signal strength RSSI, the frame error rate FER, the packet error rate, the signal to noise ratio SNR, the signal power, the bit error rate, the carrier signal to noise ratio, and the noise including the interference noise to the signal Two factors arbitrarily selected from the ratio are converted into two total metric numbers 1 and 2 according to any of Tables 1 to 3, and based on the converted two total metric numbers 1 and 2, A stable route may be determined.

  Furthermore, in the present invention, the received signal strength RSSI, the frame error rate FER, the packet error rate, the signal-to-noise ratio SNR, the signal power, the bit error rate, the carrier signal-to-noise ratio, and the noise ratio including the interference noise for the signal are used. Convert two or more arbitrarily selected factors into two or more total metrics according to any of Tables 1 to 3, and determine a more stable path based on the two or more total metrics converted You may make it do.

  In the present invention, the routing daemon 24B that determines a more stable route based on the routing table 40 constitutes a “route determination means”.

  Further, the TCP module 21, the IP module 19, the LLC module 18, the MAC module 17A, and the wireless interface module 16 that transmit or relay data along the route determined by the routing daemon 24B constitute a “communication unit”.

  Further, the received signal strength RSSI, the frame error rate FER, the packet error rate, the signal-to-noise ratio SNR, the signal power, the bit error rate, the carrier signal-to-noise ratio, and the noise ratio including interference noise to the signal are each wireless communication. "Multiple factors" representing the quality of the

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

[Embodiment 4]
FIG. 30 is a schematic block diagram in the fourth embodiment showing the configuration of radio apparatus 1 shown in FIG. The wireless device 1C according to the fourth embodiment is the same as the wireless device 1B except that the communication control unit 15B of the wireless device 1B shown in FIG. 23 is replaced with the communication control unit 15C.

  The communication control unit 15C is obtained by replacing the routing daemon 24B of the communication control unit 15B shown in FIG. 23 with the routing daemon 24C and adding a GPS (Global Positioning System) receiver 26. The rest is the same as the communication control unit 15B. It is.

  The GPS receiver 26 belongs to the physical layer, detects the current position of the wireless device 1C, and outputs it to the routing daemon 24C. More specifically, the GPS receiver 26 receives position information from a satellite (not shown), and detects the current position of the wireless device 1C by superimposing the received position information on map data. The GPS receiver 26 stores map data in a built-in memory.

  The routing daemon 24C receives the current position from the GPS receiver 26, and determines whether or not the wireless device 1C can move based on the received current position. More specifically, when the current position received from the GPS receiver 26 changes over time, the routing daemon 24C determines that the wireless device 1C is movable and the current position received from the GPS receiver 26. When the position has not changed over time, the wireless device 1C is determined not to be movable (that is, the wireless device 1C is stationary).

  When the routing daemon 24C determines that the wireless device 1C is movable, the routing daemon 24C prioritizes the total metric number 1 determined based on the received signal strength RSSI, determines a more stable route, and determines the determination. The TCP module 21, the IP module 19, the LLC module 18, the MAC module 17A, and the wireless interface module 16 are controlled so as to transmit or relay data along the path.

  Further, when the routing daemon 24C determines that the wireless device 1C is stationary, the routing daemon 24C prioritizes the total metric number 2 determined based on the communication error rate, determines a more stable route, and determines the determined route. The TCP module 21, the IP module 19, the LLC module 18, the MAC module 17A, and the wireless interface module 16 are controlled so that data is transmitted or relayed along the network.

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

  Each of the wireless devices 2 to 8 has the same configuration as the wireless device 1C illustrated in FIG.

  FIG. 31 is a flowchart in the fourth embodiment for explaining an operation of performing wireless communication between a transmission source and a transmission destination. The flowchart shown in FIG. 31 is the same as the flowchart shown in FIG. 26 except that steps S17 to S20 are added to the flowchart shown in FIG.

  When a series of operations is started, the routing daemon 24C of the wireless device 1 that is the transmission source determines whether or not the wireless device 1 can move by the above-described method based on the current position from the GPS receiver 26. Determination is made (step S17). And when it determines with the radio | wireless apparatus 1 being movable, a series of operation | movement transfers to step S21 mentioned above.

  On the other hand, when it is determined in step S17 that the wireless device 1 is not movable, the routing daemon 24C of the wireless device 1 gives priority to the total metric number 2 determined based on the communication error rate, and provides a more stable route. The TCP module 21, the IP module 19, the LLC module 18, the MAC module 17A, and the wireless interface module 16 of the wireless device 1 unicast data along the route selected by the routing daemon 24C (step S18). .

  Then, after step S18 or step S21, the routing daemon 24C such as the wireless device 2 as a repeater can move the wireless device 2 or the like by the above-described method based on the current position from the GPS receiver 26. It is determined whether or not (step S19). And when it determines with the radio | wireless apparatus 2 grade | etc., Being movable, a series of operation | movement transfers to step S22 mentioned above.

  On the other hand, when it is determined in step S19 that the wireless device 2 or the like is not movable, the routing daemon 24C of the wireless device 2 or the like gives priority to the total metric number 2 determined based on the communication error rate and is more stable. The TCP module 21, the IP module 19, the LLC module 18, the MAC module 17A, and the wireless interface module 16 such as the wireless device 2 unicast the data along the route selected by the routing daemon 24C ( Step S20).

  And after step S20 or step S22, a series of operation | movement transfers to step S23 mentioned above, and is complete | finished after performing step S23.

  The detailed operations in steps S18 and S20 are executed according to a flowchart in which “total metric number 1” is replaced with “total metric number 2” in the flowchart shown in FIG.

  As described above, in the fourth embodiment, when the wireless devices 1 to 8 are movable, priority is given to the total metric number 1 determined based on the received signal strength RSSI to determine a more stable route. Then, when the data is transmitted or relayed and is not movable, priority is given to the total metric number 2 determined based on the communication error rate, and a more stable route is determined to transmit or relay the data.

  When each of the wireless devices 1 to 8 is movable, it is necessary to quickly obtain a metric value indicating the degree of stability of the route. Therefore, priority is given to the total metric number 1 determined based on the received signal strength RSSI. We decided to determine a stable route.

  In addition, when each of the wireless devices 1 to 8 is not movable (that is, when it is stationary), each of the wireless devices 1 to 8 knows the state of the actual wireless communication more accurately and actually Since determining a more stable route based on the wireless communication status directly leads to an improvement in throughput, priority is given to the total metric number 2 determined based on the communication error rate to determine a more stable route. I decided to do it.

  The flowchart shown in FIG. 31 is a flowchart on the premise that some of the wireless devices constituting the wireless ad hoc network are moving and the other wireless devices are stationary.

  Thus, even when a wireless ad hoc network is configured by a moving wireless device and a stationary wireless device, the total metric number 1 determined based on the received signal strength RSSI and the communication error rate By using the total metric number 2 determined based on the above, data can be transmitted or relayed by determining a more stable route by a method suitable for each wireless device.

  The routing daemon 24C that determines a more stable route based on the routing table 40 constitutes a “route determination unit”.

  Further, the TCP module 21, the IP module 19, the LLC module 18, the MAC module 17A, and the wireless interface module 16 that transmit or relay data along the route determined by the routing daemon 24C constitute a “communication unit”.

  Others are the same as Embodiments 1-3.

  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 network system constructed autonomously and capable of obtaining higher throughput. In addition, the present invention is applied to a radio apparatus that constitutes a radio network system that is autonomously constructed and that can obtain higher throughput.

1 is a schematic diagram of a wireless network system according to an embodiment of the present invention. FIG. 2 is a schematic block diagram in the first embodiment showing the configuration of the wireless device 1 shown in FIG. 1. It is a block diagram of an IP header. It is a block diagram of a TCP header. It is a figure which shows the example of the routing table shown in FIG. It is a conceptual diagram of a topology message. It is a conceptual diagram of a topology table. It is a conceptual diagram of the topology created based on the topology message. 4 is a flowchart in the first embodiment for describing an operation of performing wireless communication between a transmission source and a transmission destination. 10 is a flowchart for explaining detailed operations in steps S1 and S2 shown in FIG. 9; It is another example of a routing table. It is another example of a routing table. It is a schematic diagram which shows the layout of experiment. It is a timing chart of the total metric number 1 at the time of using the conventional FSR protocol in the layout shown in FIG. FIG. 14 is a timing chart of the total metric number 1 when the protocol according to the present invention is used in the layout shown in FIG. 13. FIG. 14 is a timing chart of the total metric number 1 when the wireless device of the route on the side with the larger hop number is turned off in the layout shown in FIG. It is a figure which shows the relationship between a throughput, an error rate, and received signal strength. It is a relationship figure of the throughput and frequency in TCP mode. It is a relationship figure of the throughput and frequency in UDP mode. It is a relationship figure of delay time and frequency. FIG. 3 is a schematic block diagram in Embodiment 2 showing the configuration of the wireless device shown in FIG. 1. It is a conceptual diagram for demonstrating the method of calculating a frame error rate. It is a figure which shows the example of the routing table shown in FIG. FIG. 10 is a schematic block diagram in the third embodiment showing the configuration of the wireless device shown in FIG. 1. It is a figure which shows the example of the routing table shown in FIG. 10 is a flowchart in Embodiment 3 for explaining an operation of performing wireless communication between a transmission source and a transmission destination. 27 is a flowchart for explaining detailed operations in steps S21 and S22 shown in FIG. It is another example of the routing table shown in FIG. It is a further another example of the routing table shown in FIG. FIG. 10 is a schematic block diagram in the fourth embodiment showing the configuration of the wireless device shown in FIG. 1. 15 is a flowchart in the fourth embodiment for explaining an operation of performing wireless communication between a transmission source and a transmission destination. It is a conceptual diagram of an ad hoc network. It is a conceptual diagram of the radio | wireless communication between adjacent terminals. It is another conceptual diagram of the radio | wireless communication between adjacent terminals. It is a relationship diagram of a throughput and the number of hops.

Explanation of symbols

    1-8, 1A, 1B, 1C Wireless device, 10 Wireless network system, 11 Antenna, 12 Input unit, 13 Display unit, 14 E-mail application, 15, 15A, 15B, 15C Communication control unit, 16, 16A Wireless interface module 17, 17A MAC module, 18 LLC module, 19 IP module, 20, 20A, 20B, 20C, 30, 40, 40A, 40B, 40C, 40D Routing table, 21 TCP module, 22 UDP module, 23 SMTP module, 24 , 24A, 24B, 24C Routing daemon, 25 timer, 26 GPS receiver, 50 space, 200 ad hoc network, 201-206 automobile.

Claims (8)

A wireless device that is autonomously established and constitutes a wireless network that performs wireless communication between a transmission source and a transmission destination,
Route determining means for determining a route having a relatively high degree of stability as a route for performing the wireless communication;
A wireless device comprising: communication means for performing the wireless communication along the route determined by the route determining means.   The wireless device according to claim 1, wherein the degree of stability is determined based on at least one factor arbitrarily selected from a plurality of factors each representing the quality of the wireless communication.   The wireless device according to claim 2, wherein the degree of stability is determined using at least one path stability index arbitrarily selected from a plurality of path stability indices obtained by converting the plurality of factors.   The wireless device according to claim 3, wherein the degree of stability is determined based on two path stability indices arbitrarily selected from the plurality of path stability indices.   The radio apparatus according to claim 3 or 4, wherein the plurality of factors are converted into the plurality of path stability indexes so that the path stability index changes exponentially as the factor changes linearly. .   The wireless device according to any one of claims 2 to 5, wherein the plurality of factors include a received signal strength, a frame error rate, a packet error rate, a signal-to-noise ratio, and a bit error rate.   The wireless device according to any one of claims 1 to 6, wherein the route determination unit further determines a route for performing the wireless communication so that the number of relays to the transmission destination is reduced. .   A wireless network system comprising the wireless device according to any one of claims 1 to 7.

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