JP2008193558A - Wireless network - Google Patents

Abstract

A wireless network capable of easily executing channel assignment is provided.
A wireless network includes a plurality of wireless devices arranged in a mesh shape. Among the wireless devices 31 to 55, the wireless devices 36 to 40, 42, 44, and 46 to 50, which are MPRs, have a larger number of wireless devices that request retransmission of packets themselves, or the number of adjacent MPRs. The larger the number, the shorter the back-off time is calculated, and channel assignment is performed in the order in which the calculated back-off time has expired. Then, when the channel assignment is completed, the wireless devices 36 to 40, 42, 44, and 46 to 50 indicate the contents of the channel assignment, and the adjacent wireless device requests a channel assignment request for channel assignment in the adjacent wireless device. Send to. The wireless devices 31 to 35, 41, 43, 45, and 51 to 55 other than the MPR perform channel allocation in response to the channel allocation request.
[Selection] Figure 7

Description

  The present invention relates to a wireless network, and more particularly to a wireless network constructed autonomously.

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

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

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

  Conventionally, it has been proposed to apply a plurality of network interface cards to a wireless device used in an ad hoc network (Non-Patent Documents 1 to 3).

  In Non-Patent Document 1, a plurality of network interface cards are applied when the same number of network interface cards and channels exist. Then, static channel allocation is performed for all terminals so that channel Channel-1 is allocated to network interface card NIC-1 and channel Channel-2 is allocated to network interface card NIC-2. . This proposal can increase network capacity linearly with the number of network interface cards used.

  Further, in Non-Patent Document 2, the load detection channel allocation algorithm and routing algorithm integrated in the center have an access where a gateway connected to a wired network exists and communication to the gateway or communication from the gateway dominates. It has been proposed for a wireless mesh network using a plurality of network interface cards in a network. Then, it is assumed that communication profile information exists for the notified channel assignment. As a result, it has been shown that more capacity improvements can be achieved than linear capacity improvements by using more network interface cards.

  Furthermore, in Non-Patent Document 3, one of the first distributed channel assignments is proposed for the same access scenario as described above. And by giving a higher priority to a terminal closer to the gateway, this terminal can select a channel with less radio wave interference than a terminal farther from the gateway.

Similar capacity gains have also been proposed in local algorithms using 2-hop neighbor information.
R. Draves, J. Padhye, and B. Zill, “Routing in multi-radio, multi-hop wireless mesh networks”, in Proc. Mobicom, Philadelphia, PA, USA, 2004, pp. 114-128. A. Raniwala, K. Gopalan, and T.-c. Chiueh, “Centralized channel assignment and routing algorithms for multi-channel wireless mesh networks”, ACMSIGMOBILE Mobile Computing and Communications Review, vol. 8, pp. 50-65, 2004 . A. Raniwala and T.-c. Chiueh, “Architecture and algorithms for IEEE 802.11-based multi-channel wireless mesh network”, in Proc. INFOCOM, Miami, FL, USA, 2005, pp.2223-2234.

  However, in a general wireless mesh network where there is no gateway, it is not clear how to select a terminal similar to the gateway for priority-based channel assignment. It is not easy to apply to a general wireless mesh network where there is no gateway.

  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 capable of easily executing channel assignment.

  According to this invention, the wireless network is a wireless network established autonomously, and includes a plurality of first wireless devices and a plurality of second wireless devices. The plurality of first wireless devices perform channel assignment in descending order of priority. The plurality of second radio apparatuses perform channel allocation in response to a channel allocation request from at least one of the plurality of first radio apparatuses.

  Preferably, the plurality of first wireless devices determine priority among each other.

  Preferably, each of the plurality of second radio apparatuses performs channel allocation according to a result of channel allocation in the first radio apparatus accessed by itself.

  Preferably, each of the plurality of first wireless devices is a wireless device included in a relay wireless device group that relays a packet to all the wireless devices constituting the wireless network with a minimum necessary number of relays.

  Preferably, the plurality of first wireless devices exist in the same communication range.

  Preferably, the plurality of first radio apparatuses perform channel assignment in the order in which a random back-off time given to each radio apparatus has elapsed.

  Preferably, the plurality of first wireless devices perform channel assignment in descending order of the number of wireless devices requesting packet relay and / or the number of wireless devices included in the relay wireless device group among neighboring wireless devices. .

  Preferably, each of the plurality of first wireless devices assigns the minimum interference channel with the smallest radio wave interference as a channel used for communication with the wireless devices included in the relay wireless device group, and relays the packet to itself as another channel. Assigned as a channel to be used for communication with a wireless device requesting.

  Preferably, each of the plurality of first wireless devices detects the minimum interference channel by exchanging information with a wireless device existing in a 2-hop region from itself.

  Preferably, each of the plurality of first wireless devices has a plurality of interfaces, and when channel assignment is not performed for all of the plurality of interfaces, different channels are assigned to the plurality of interfaces. When channel assignment is completed for some of the plurality of interfaces, a channel different from the channel assigned to the interface for which channel assignment has been completed is assigned to an interface for which channel assignment has not been completed. .

  Preferably, each of the plurality of first wireless devices maintains a channel of the interface for which channel assignment is completed when channel assignment is completed for some of the plurality of interfaces.

  Preferably, each of the plurality of first wireless devices has a plurality of interfaces, and a channel used for communication with the wireless devices included in the relay wireless device group is assigned to all of the plurality of interfaces. When maintaining channels assigned to multiple interfaces.

  In the wireless network according to the present invention, the plurality of first wireless devices determine the order of channel assignment among each other and perform channel assignment according to the determined order. Thereafter, the plurality of second wireless devices perform channel assignment in response to a channel assignment request from at least one of the plurality of first wireless devices. That is, in the wireless network according to the present invention, channel assignment is performed in the order in which a plurality of wireless devices are automatically determined.

  Therefore, according to the present invention, channel assignment can be easily performed in a wireless network in which a wireless device such as a gateway serving as a reference when determining the order of channel assignment does not exist.

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

    FIG. 1 is a schematic diagram of a wireless network according to an embodiment of the present invention. The wireless network 100 includes wireless devices 31 to 55. The wireless devices 31 to 55 are arranged in a mesh shape in the wireless communication space, and autonomously configure a wireless mesh network. Each of the wireless devices 31 to 55 includes, for example, two network interfaces NIF1 and NIF2, and performs wireless communication using the two network interfaces NIF1 and NIF2. As will be described later, each of the antennas 61 to 85 includes two antennas corresponding to the two network interfaces NIF1 and NIF2. The antennas 61 to 85 are attached to the wireless devices 31 to 55, respectively.

  In the wireless network 100, each of the wireless devices 31 to 55 can perform direct wireless communication with adjacent wireless devices existing in the horizontal and vertical directions on the paper surface of FIG. Wireless communication cannot be performed directly with a wireless device existing in the network.

    Accordingly, when the wireless device 31 performs wireless communication with the wireless device 55, for example, the wireless device 31 can perform wireless communication with the wireless device 55 via the wireless devices 32-35, 40, 45, and 50. Wireless communication can be performed with the wireless device 55 via the wireless devices 36, 41, 46, 51 to 54, and wireless devices can be connected via the wireless devices 36, 37, 42, 43, 48, 49, 50. Wireless communication can be performed with 55.

    Thus, in the wireless network 100, each of the wireless devices 31 to 55 performs wireless communication with a transmission destination via a plurality of wireless devices, that is, by multi-hop.

  However, in order to improve the communication capacity of the wireless network 100, it is necessary to assign different channels to the two network interfaces NIF1 and NIF2 included in the wireless devices 31 to 55. However, the wireless device is similar to a gateway. In the wireless network 100 in which there is no such channel assignment is not easy.

  Therefore, in the following, a method for easily allocating channels in the wireless network 100 in which no wireless device similar to the gateway exists will be described.

  In the embodiment of the present invention, the OLSR protocol is used as a protocol for establishing a wireless communication path between a transmission source and a transmission destination. The OLSR protocol is a table-driven routing protocol, and is a protocol for exchanging route information using a Hello message and a TC (Topology Control) message to create a routing table.

  FIG. 2 is a schematic block diagram showing the configuration of the wireless device 31 shown in FIG. The wireless device 31 includes antennas 10 and 11, an input unit 12, an output unit 13, a user application 14, and a communication control unit 15.

  The antennas 10 and 11 constitute each of the antennas 61 to 85 shown in FIG. Each of the antennas 10 and 11 receives data from another wireless device via the wireless communication space, outputs the received data to the communication control unit 15, and wirelessly communicates the data from the communication control unit 15. Transmit to other wireless devices via space.

  The input unit 12 receives a message and data destination input by an operator of the wireless device 31 and outputs the received message and destination to the user application 14. The output unit 13 displays a message according to control from the user application 14.

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

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

  The wireless interface module 16 belongs to the physical layer and includes two network interfaces NIF1 and NIF2. The wireless interface module 16 modulates and demodulates the transmission signal or the reception signal according to a predetermined rule and transmits / receives a signal using at least one of the two network interfaces NIF1 and NIF2. In this case, different channels are assigned to the two network interfaces NIF1 and NIF2.

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

  That is, the MAC module 17 broadcasts the Hello packet received from the routing daemon 24 via the wireless interface module 16. The MAC module 17 performs retransmission control of data (packets).

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

  The IP module 20 belongs to the Internet layer, and allocates channels to the two network interfaces NIF1 and NIF2 included in the wireless interface module 16 by a method described later. Further, in the channel assignment process, the IP module 20 generates a channel change request CHANGE_CHAN and broadcasts the generated channel change request CHANGE_CHAN.

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

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

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

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

  The UDP module 23 belongs to the transport layer, 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 routing daemon 24 belongs to the process / application layer, monitors the execution state of other communication control modules, and processes requests from other communication control modules.

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

  Note that each of the wireless devices 32 to 55 illustrated in FIG. 1 has the same configuration as the configuration of the wireless device 31 illustrated in FIG. 2.

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

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

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

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

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

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

  FIG. 4 is a configuration diagram of the routing table 21 shown in FIG. The routing table 21 includes a transmission destination, a next wireless device, and the number of hops. The transmission destination, the next wireless device, and the number of hops are associated with each other. “Destination” represents the IP address of the destination wireless device. “Next wireless device” represents the IP address of the wireless device to be transmitted next when transmitting the packet PKT to the transmission destination. “Hop number” represents the number of hops to the destination. For example, in FIG. 1, the wireless device 31 and the wireless device are routed by a route of the wireless device 31 -the wireless device 32 -the wireless device 33 -the wireless device 34 -the wireless device 35 -the wireless device 40 -the wireless device 45 -the wireless device 50- When wireless communication is performed with 55, “7” is stored in the hop count of the routing table 21 of the wireless device 32.

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

  In the present invention, each of the wireless devices 31 to 55 creates the routing table 21 according to the OLSR protocol. The creation of the routing table 21 according to the OLSR protocol will be described in detail. When creating the routing table 21, the wireless devices 31 to 55 transmit and receive a Hello message and a TC message.

  The Hello message is periodically transmitted for the purpose of distributing information held by the wireless devices 31 to 55. By receiving this Hello message, each of the wireless devices 31 to 55 can collect information on peripheral wireless devices, and recognizes what wireless devices exist around the wireless device.

  In the OLSR protocol, each of the wireless devices 31 to 55 manages local link information. The Hello message is a message for constructing and transmitting the local link information. The local link information includes “link set”, “neighboring wireless device set”, “two-hop neighboring wireless device set and link set to those wireless devices”, “MPR set”, and “MPR selector set”.

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

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

  The MPR set is a set of wireless devices selected as MPRs. The MPR is a relay so that the packet PKT can be transmitted to all the wireless devices 31 to 55 by the minimum necessary number of communication when each packet PKT is transmitted to all the wireless devices 31 to 55 in the wireless network 100. Selecting a wireless device.

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

  The process of establishing local link information is generally as follows. In the initial stage of the Hello message, each of the wireless devices 31 to 55 transmits a Hello message containing its own address to an adjacent wireless device in order to notify the presence of the self. All of the wireless devices 31 to 55 perform this operation, and each of the wireless devices 31 to 55 grasps what address a wireless device has around itself. In this way, a link set and an adjacent wireless device set are constructed.

  The constructed local link information is continuously sent again by a Hello message again. By repeating this, it is gradually clarified whether each link is bidirectional or what kind of wireless device exists ahead of the adjacent wireless device. Each of the wireless devices 31 to 55 stores local link information that is gradually constructed in this way.

  Furthermore, information regarding MPR is also periodically transmitted by a Hello message and notified to each of the wireless devices 31 to 55. Each of the wireless devices 31 to 55 selects several wireless devices from among neighboring wireless devices as an MPR set as wireless devices that request retransmission of the packet PKT transmitted by itself. Then, since the information regarding the MPR set is transmitted to the adjacent wireless device by the Hello message, the wireless device that has received the Hello message sets the set of wireless devices that have selected itself as the MPR as the “MPR selector set”. to manage. In this way, each of the wireless devices 31 to 55 can immediately recognize from which wireless device the packet PKT received should be retransmitted.

  When a local link set is established in each of the wireless devices 31 to 55 by transmission / reception of the Hello message, a TC message for notifying the topology of the entire wireless network 100 is transmitted to the wireless devices 31 to 55. This TC message is periodically transmitted by all wireless devices selected as MPRs. Since the TC message includes a link between each wireless device and the MPR selector set, all the wireless devices 31 to 55 in the wireless network 100 know all the MPR sets and all the MPR selector sets. And the topology of the entire wireless network 100 can be known based on all MPR sets and all MPR selector sets. Each of the wireless devices 31 to 55 calculates the shortest path using the topology of the entire wireless network 100 and creates a route table based on the calculated shortest path.

  In addition, each radio | wireless apparatus 31-55 exchanges a TC message frequently separately from a Hello message. MPR is also used for exchanging TC messages.

  Each of the wireless devices 31 to 55 transmits and receives the above-mentioned Hello message and TC message, recognizes the topology of the entire wireless network 100, calculates the shortest path based on the recognized topology of the entire wireless network 100, and based on this Thus, the routing table 21 shown in FIG. 4 is dynamically created.

  Hereinafter, channel allocation according to the present invention will be described. FIG. 6 is a functional block diagram of channel assignment in each of the radio apparatuses 31 to 55. In each of the wireless devices 31 to 55, the IP module 20 includes a channel assignment unit 201 and a timer 202. In each of the wireless devices 31 to 55, the wireless interface module 16 includes network interfaces NIF1 and NIF2. The network interface NIF1 is connected to the antenna 10 and the network interface NIF2 is connected to the antenna 11.

The channel assignment unit 201 calculates the back-off time b (c _i , m _i ) according to the following equation.

In the equation (1), _{c i} is the number of the selected wireless device as MPR (either = radio apparatus 31-55) wireless unit i, _{m i} is adjacent radio adjacent to the wireless device i This is the number of wireless devices that are MPRs of the devices. Also, r is a random integer included in the range [0, ∞), d is the average terminal degree, and s is a scaling factor.

Then, the channel allocation unit 201, the back-off time _{b (c i, m} i) when calculating the requests the calculated back-off time _{b (c i, m} i) the measurement of the timer 202.

  Further, the channel allocation unit 201 receives a Hello packet from the routing daemon 24, detects information of an adjacent wireless device in the 2-hop region from the wireless device on which it is installed based on the received Hello packet, The minimum interference channel Ch_ITF_MIN that minimizes radio wave interference is determined based on the information of the adjacent wireless device in the detected 2-hop region. More specifically, the channel allocating unit 201 investigates the degree of congestion of packets transmitted and received on each of the channels Ch1 and Ch2 using a sniffer (SNIFFER is a registered trademark), and determines the degree of packet congestion. Is the smallest interference channel Ch_ITF_MIN. Then, the channel assignment unit 201 holds the determined minimum interference channel Ch_ITF_MIN.

When the timer 202 measures the backoff time b (c _i , m _i ), the channel allocation unit 201 performs channel allocation for each of the network interfaces NIF1 and NIF2. More specifically, the channel assignment unit 201 assigns the minimum interference channel Ch_ITF_MIN to a network interface (one of the network interfaces NIF1 and NIF2) that performs wireless communication with a wireless device that is an MPR, and wirelessly communicates with wireless devices other than the MPR. A channel other than the minimum interference channel Ch_ITF_MIN is allocated to a network interface (one of the network interfaces NIF1 and NIF2) that performs communication.

  Further, when the channel allocation unit 201 allocates a channel to the network interfaces NIF1 and NIF2, the channel allocation unit 201 generates and broadcasts a channel change request CHANGE_CHAN indicating the content of the channel allocation.

The timer 202 measures the back-off time b (c _i , m _i ) in response to a request from the channel assignment means 201, and when the measurement of the back-off time b (c _i , m _i ) ends, the back-off time b An expiration signal EXPIRE indicating that (c _i , m _i ) has expired is output to the channel allocation means 201.

  Each of network interfaces NIF1 and NIF2 transmits and receives a packet using the channel received from channel assignment means 201.

  FIG. 7 is a diagram illustrating an MPR set in the wireless network 100. In the wireless network 100, for example, the wireless devices 36 to 40, 42, 44, and 46 to 50 constitute an MPR set. In FIG. 7, the numbers described above the wireless devices 36 to 40, 42, 44, 46 to 50 are the wireless devices that request the wireless devices 36 to 40, 42, 44, 46 to 50 to retransmit packets. It is the number of the device (= MPR selector).

  The wireless device 36 receives broadcast packets from the wireless devices 31, 37, and 41 and retransmits the received broadcast packets. The wireless device 37 receives broadcast packets from the wireless devices 32, 36, 38, and 42. At the same time, the received broadcast packet is retransmitted.

  The wireless device 38 receives broadcast packets from the wireless devices 33, 37, 39, and 43 and retransmits the received broadcast packets. The wireless device 39 broadcasts from the wireless devices 34, 38, 40, and 44. A packet is received and the received broadcast packet is retransmitted.

  Further, the wireless device 40 receives broadcast packets from the wireless devices 35, 39, and 45 and retransmits the received broadcast packets, and the wireless device 42 receives broadcast packets from the wireless devices 37, 43, and 47. At the same time, the received broadcast packet is retransmitted.

  Further, the wireless device 44 receives broadcast packets from the wireless devices 39, 43, and 49 and retransmits the received broadcast packets. The wireless device 46 receives broadcast packets from the wireless devices 47 and 51, and The received broadcast packet is retransmitted.

  Further, the wireless device 47 receives broadcast packets from the wireless devices 42, 46, 48, 52 and retransmits the received broadcast packets. The wireless device 48 broadcasts from the wireless devices 43, 47, 49, 53. A packet is received and the received broadcast packet is retransmitted.

  Further, the wireless device 49 receives broadcast packets from the wireless devices 44, 48, 50, 54 and retransmits the received broadcast packets, and the wireless device 50 receives broadcast packets from the wireless devices 49, 55. At the same time, the received broadcast packet is retransmitted.

  Then, the wireless devices 31 to 35, 41, 43, 45, and 51 to 55 receive broadcast packets from other wireless devices and do not retransmit the received broadcast packets.

As described above, when the wireless devices 31 to 55 configuring the wireless network 100 in which the MPR set is present are activated, each of the wireless devices 31 to 55 has a random backoff time b (c _i , m _i ) is calculated, and when the calculated back-off time b (c _i , m _i ) expires, channels Ch 1 and Ch 2 are allocated to its two network interfaces NIF 1 and NIF 2.

More specifically, in each of the wireless devices 31 to 55, the channel allocation unit 201 calculates a random backoff time b (c _i , m _i ) according to the equation (1), and calculates the calculated backoff time b. The timer 202 is requested to measure (c _i , m _i ). In each of the wireless devices 31 to 55, the timer 202 measures the back-off time b (c _i , m _i ) in response to a request from the channel allocation unit 201, and the back-off time b (c _i , m _When the measurement of _i ) is completed, an expiration signal EXPIRE indicating that the back-off time b (c _i , m _i ) has expired is output to the channel allocation means 201.

  Then, in each of the wireless devices 31 to 55, the channel assignment unit 201 assigns the channels Ch1 and Ch2 to the network interfaces NIF1 and NIF2 in response to the expiration signal EXPIRE from the timer 202, respectively.

Note that the MPR set is broadcast in the wireless network 100 by a TC message, and the wireless devices 31 to 55 know the topology of the wireless devices 31 to 55 configuring the wireless network 100. among the neighboring wireless device, any number of wireless devices can detect whether the MPR (i.e., can be detected m _i). Each wireless device 31 to 55 establishes local link information, and since the local link information includes an MPR selector set that is a set of wireless devices that have selected themselves as MPRs, the wireless devices 31 to 55 are requested to retransmit packets. The number of wireless devices (= c _i ) can be detected. Furthermore, r in the formula (1) is an integer randomly selected from [0, ∞), and d, s, and slot_time are constants. Accordingly, each of the wireless devices 31 to 55 can calculate the back-off time b (c _i , m _i ) according to the equation (1). When the wireless devices 31 to 55 are arranged in a mesh shape, d is set to “4”.

When the back-off time b (c _i , m _i ) is calculated according to the equation (1) in the wireless devices 36 to 40, 42, 44, and 46 to 50 that are MPRs among the wireless devices 31 to 55, the calculation The length of the backoff time b (c _i , m _i ) that is determined differs depending on whether or not the wireless device i is an MPR and how many MPRs are included in adjacent wireless devices adjacent to the wireless device i. That is, Equation (1) shows a c _i indicating the number of wireless devices to request retransmission of the packet to the wireless device i, the number of wireless devices is a MPR of the adjacent radio devices adjacent to the wireless device i and a m _i, back-off time _{b (c} i, _{m i)} the length of the more likely to be shorter according to _{c i} and _{m i} is increased, becomes longer as _{c i} and _{m i} is smaller probability Becomes higher.

It c _i is not "0", it means that the wireless device i is MPR, wireless device 31～35,41,43,45,51～55 not MPR, the wireless device is MPR 36-40 , 42, 44, 46 to 50 perform channel allocation in response to a channel change request CHANGE_CHAN transmitted after channel allocation, so that the wireless devices 36 to 40, 42, 44, 46 to 50, which are MPRs, The channels Ch1 and Ch2 are assigned to the network interfaces NIF1 and NIF2 at an earlier timing than the wireless devices 31 to 35, 41, 43, 45, and 51 to 55 that are not present.

It c _i is large, it means that the number of wireless devices to request retransmission of the packet to the wireless device i is greater, in the inter-radio device is MPR, re packets from more wireless devices The wireless device requested to transmit assigns the channels Ch1 and Ch2 to the network interfaces NIF1 and NIF2 at a relatively earlier timing. For example, the wireless device 47 is requested to retransmit a packet from the four wireless devices 42, 46, 48, and 53 as described above, and the wireless device 46 is transmitted from the two wireless devices 47 and 51 as described above. Since the packet is requested to be retransmitted, the wireless device 47 assigns the channels Ch1 and Ch2 to the network interfaces NIF1 and NIF2 at a timing earlier than that of the wireless device 46.

Further, if _mi is not “0”, it means that at least one wireless device among the wireless devices adjacent to the wireless device i is MPR. Channels Ch1 and Ch2 are allocated to the network interfaces NIF1 and NIF2 at a timing earlier than that of a wireless device that is not MPR.

Furthermore, since a large m _i means that a relatively large number of wireless devices among the wireless devices adjacent to the wireless device i are MPRs, the wireless device i is a relative device among the adjacent wireless devices. Therefore, the channels Ch1 and Ch2 are allocated to the network interfaces NIF1 and NIF2 at a timing earlier than that of the wireless devices that are MPR. For example, in the wireless device 39, of the four adjacent wireless devices (= wireless devices 34, 38, 40, 44), three wireless devices 38, 40, 44 are MPRs, and four wireless devices 44 are included. Of the adjacent wireless devices (= wireless devices 39, 43, 45, 49) are MPR, the wireless device 39 is the network interface NIF1, at an earlier timing than the wireless device 49. Channels Ch1 and Ch2 are assigned to NIF2.

The wireless device 37,39,47,49 have the same _{c i} and _{m i,} "r" is included in the formula (1), [0, since arbitrarily from ∞) is chosen integer The back-off times calculated in the wireless devices 37, 39, 47, and 49 are all less likely to be the same, and the probability that the wireless devices 37, 39, 47, and 49 perform channel assignment at different timings is high.

  Therefore, in the present invention, among the wireless devices 31 to 55 configuring the wireless network 100, the MPR is requested to retransmit a packet from a relatively large number of wireless devices, and among the adjacent wireless devices, A relatively large number of wireless devices are MPRs, and channels Ch1 and Ch2 are assigned to network interfaces NIF1 and NIF2 at the earliest timing. MPRs are requested to retransmit packets by relatively many wireless devices. Further, among the adjacent wireless devices, a wireless device in which relatively few wireless devices are MPRs allocates channels Ch1 and Ch2 to the network interfaces NIF1 and NIF2 at the second earliest timing, and is an MPR. A wireless device requested to retransmit a packet by many wireless devices Channels Ch1 and Ch2 are allocated to the network interfaces NIF1 and NIF2 at the earliest timing, and the wireless device that is the MPR and requested to retransmit the packet from the relatively few radio devices is the network interface NIF1 at the fourth earliest timing. , NIF2 are assigned channels Ch1 and Ch2, and a network interface used for wireless communication with a wireless device that is MPR at the latest timing when a wireless device that is not MPR receives a channel change request CHANGE_CHAN from the wireless device that is MPR. A channel (any one of channels Ch1 and Ch2) is assigned to one of network interfaces NIF1 and NIF2.

  That is, in the wireless network 100, the wireless devices 37, 39, 47, and 49 assign the channels Ch1 and Ch2 to the network interfaces NIF1 and NIF2 at the earliest timing, and the wireless devices 38 and 48 are the network interface at the second earliest timing. The channels Ch1 and Ch2 are assigned to the NIF1 and NIF2, and the wireless devices 36, 40, 46, and 50 assign the channels Ch1 and Ch2 to the network interfaces NIF1 and NIF2 at the third earliest timing, and the wireless devices 31 to 35, 41, and 43 , 45, 51 to 55 assign one of the channels Ch1 and Ch2 to one of the network interfaces NIF1 and NIF2 at the latest timing.

  As a result, the wireless devices 31 to 55 automatically adjust the timing for assigning the channels Ch1 and Ch2 to the network interfaces NIF1 and NIF2, and assign the channels Ch1 and Ch2 to the network interfaces NIF1 and NIF2 at the adjusted timing.

  Therefore, according to the present invention, channels can be easily allocated even if the wireless network 100 does not include a gateway serving as a reference for determining channel allocation timing.

  The channel assignment to the network interfaces NIF1 and NIF2 will be described in more detail. FIG. 8 is a diagram for explaining the channel allocation method in detail. In addition, the radio | wireless apparatuses 31-33, 36-38, 41-43 are arrange | positioned in the mesh form within the same communication range. In FIG. 8, the numbers assigned to the wireless devices 31 to 33, 36 to 38, and 41 to 43 represent the channel assignment order.

  The wireless device 37 is an MPR, and the number of wireless devices that have requested the retransmission of the packet is four (= wireless devices 32, 36, 38, 42), and the adjacent wireless devices 32, 36, 38, 42 are present. Of these, since the three wireless devices 36, 38, 42 are MPRs, the channels Ch1, Ch2 are connected to the network interfaces NIF1, NIF2 at the earliest timing among the wireless devices 31-33, 36-38, 41-43. assign.

  In this case, the channel allocation unit 201 of the wireless device 37 is a network for performing wireless communication with the wireless devices 36, 38, 42 because the wireless devices 36, 38, 42 adjacent to the wireless device 37 are MPRs. The channel Ch1 is assigned to the interface NIF1, and the channel Ch2 is assigned to the network interface NIF2 for performing wireless communication with the wireless device 32 that is not the MPR. The channel Ch1 is the minimum interference channel Ch_ITF_MIN with the smallest radio wave interference, and the channel Ch2 is a channel other than the minimum interference channel Ch_ITF_MIN.

  As described above, the channel assignment unit 201 of the wireless device 37 that performs channel assignment first assigns different channels Ch1 and Ch2 to the two network interfaces NIF1 and NIF2.

  When the channel assignment unit 201 of the wireless device 37 assigns the channels Ch1 and Ch2 to the network interfaces NIF1 and NIF2, respectively, the channel Ch1 (=) is assigned to the network interface NIF1 for performing wireless communication with the wireless devices 36, 38, and 42. Channel change request CHANGE_CHAN1 = [NIF1 (Ch1) → IPaddress36, IPaddress38, IPaddress42 / IPaddress42 / IPaddress42 / IPaddress42 / IPaddress42 / IPaddress42 / IPaddress42 / IPaddress42 / IPaddress42 / IPaddress42 / IPaddress42 / NIF2 (Ch2) → IPaddress32 / IPaddress37] and the generated channel change request CHANGE_ HAN1 = [NIF1 (Ch1) → IPaddress36, IPaddress38, IPaddress42 / NIF2 (Ch2) → IPaddress32 / IPaddress37] a broadcast to the wireless device 32,36,38,42 adjacent.

  The channel assignment unit 201 of the wireless devices 32, 36, 38, 42 sends the channel change request CHANGE_CHAN1 = [NIF1 (Ch1) → IPaddress36, IPaddress38, IPaddress42 / NIF2 (Ch2) → IPaddress32 / IPaddress37] transmitted from the wireless device 37. Receive.

  Then, the channel assignment unit 201 of the wireless device 38 performs channel assignment next to the wireless device 37 in response to the received channel change request CHANGE_CHAN1. More specifically, the channel assignment unit 201 of the wireless device 38 refers to the channel change request CHANGE_CHAN1 = [NIF1 (Ch1) → IPaddress36, IPaddress38, IPaddress42 / NIF2 (Ch2) → IPaddress32 / IPaddress37]. Detects that channel Ch1 has been assigned to network interface NIF1 for wireless communication with itself. Then, the channel assignment unit 201 of the wireless device 38 determines the network interface NIF1 as a network interface for performing wireless communication with the wireless device 37, assigns the channel Ch1 to the determined network interface NIF1, and in MPR, The network interface NIF2 is determined as a network interface for performing wireless communication with the non-wireless devices 33 and 43, and the channel Ch2 is assigned to the determined network interface NIF2.

  Then, the channel assignment unit 201 of the wireless device 38 generates a channel change request CHANGE_CHAN2 = [NIF1 (Ch1) → IPaddress37 / NIF2 (Ch2) → IPaddress33, IPaddress43 / IPaddress38] indicating the contents of channel assignment in the wireless device 38, The generated channel change request CHANGE_CHAN2 = [NIF1 (Ch1) → IPaddress37 / NIF2 (Ch2) → IPaddress33, IPaddress43 / IPaddress38] is broadcast to the adjacent wireless devices 33, 37, 43.

  After the channel assignment in the wireless device 38 is completed, the channel assignment means 201 of the wireless device 36 responds to the channel change request CHANGE_CHAN1 received from the wireless device 37 by the same method as the channel assignment method in the wireless device 38. The network interface NIF1 is determined as a network interface for performing wireless communication with the network 37, the channel Ch1 is assigned to the determined network interface NIF1, and wireless communication is performed with the wireless devices 31 and 41 that are not MPRs. A network interface for the network interface NIF2 is determined, and the channel Ch2 is assigned to the determined network interface NIF2.

  Then, the channel assignment unit 201 of the wireless device 36 generates a channel change request CHANGE_CHAN3 = [NIF1 (Ch1) → IPaddress37 / NIF2 (Ch2) → IPaddress31, IPaddress41 / IPaddress36] indicating the contents of the channel assignment in the wireless device 36, The generated channel change request CHANGE_CHAN3 = [NIF1 (Ch1) → IPaddress37 / NIF2 (Ch2) → IPaddress31, IPaddress41 / IPaddress36] is broadcast to the adjacent wireless devices 31, 37, 41.

  After the channel assignment in the wireless device 36 is completed, the channel assignment means 201 of the wireless device 42 responds to the channel change request CHANGE_CHAN1 received from the wireless device 37 by the same method as the channel assignment method in the wireless device 36. The network interface NIF1 is determined as a network interface for performing wireless communication with the network 37, the channel Ch1 is assigned to the determined network interface NIF1, and wireless communication is performed with the wireless devices 41 and 43 that are not MPRs. A network interface for the network interface NIF2 is determined, and the channel Ch2 is assigned to the determined network interface NIF2.

  Then, the channel assignment unit 201 of the wireless device 42 generates a channel change request CHANGE_CHAN4 = [NIF1 (Ch1) → IPaddress 37 / NIF2 (Ch2) → IPaddress 41, IPaddress 43 / IPaddress 42] indicating the contents of the channel assignment in the wireless device 42, The generated channel change request CHANGE_CHAN4 = [NIF1 (Ch1) → IPaddress37 / NIF2 (Ch2) → IPaddress41, IPaddress43 / IPaddress42] is broadcast to the adjacent wireless devices 37, 41, 43.

  After the channel assignment in the wireless device 42 is completed, the channel assignment means 201 of the wireless device 32 receives the channel change request CHANGE_CHAN1 = [NIF1 (Ch1) → IPaddress36, IPaddress38, IPaddress42 / NIF2 (Ch2) → IPaddress32 received from the wireless device 37. / IPaddress 37], the network interface NIF2 is determined as the network interface for the wireless device 37 to perform wireless communication with the wireless device 32, and it is detected that the channel Ch2 is assigned to the determined network interface NIF2. To do.

  Then, the channel assignment unit 201 of the wireless device 32 determines the network interface NIF2 as a network interface for performing wireless communication with the wireless device 37, and assigns the channel Ch2 to the determined network interface NIF2.

  Then, the channel assignment unit 201 of the wireless device 32 generates a channel change request CHANGE_CHAN5 = [NIF2 (Ch2) → IPaddress37 / IPaddress32] indicating the contents of the channel assignment in the wireless device 32, and the generated channel change request CHANGE_CHAN5 = [ NIF2 (Ch2) → IPaddress37 / IPaddress32] is transmitted to the adjacent wireless device 37.

  The wireless device 43 receives the channel change request CHANGE_CHAN2 from the wireless device 38 and receives the channel change request CHANGE_CHAN4 from the wireless device 42. Then, the channel assignment unit 201 of the wireless device 43 determines the network interface NIF2 as a network interface for the wireless device 38 to perform wireless communication with the wireless device 43 based on the channel change request CHANGE_CHAN2, and determines the determined network. It is detected that the channel Ch2 is allocated to the interface NIF2, and the network interface NIF2 determines the network interface for the wireless device 42 to perform wireless communication with the wireless device 43 based on the channel change request CHANGE_CHAN4. It is detected that the channel Ch2 is assigned to the network interface NIF2 that has been selected.

  Thereafter, the channel assignment unit 201 of the wireless device 43 determines the network interface NIF2 as a network interface for performing wireless communication with the wireless device 38, assigns the channel Ch2 to the determined network interface NIF2, and The network interface NIF2 is determined as a network interface for performing wireless communication with the network 42, and the channel Ch2 is assigned to the determined network interface NIF2.

  Then, the channel assignment unit 201 of the wireless device 43 generates a channel change request CHANGE_CHAN6 = [NIF2 (Ch2) → IPaddress38, IPaddress42 / IPaddress43] indicating the contents of the channel assignment in the wireless device 43, and the generated channel change request CHANGE_CHAN6 = [NIF2 (Ch2) → IPaddress 38, IPaddress 42 / IPaddress 43] is broadcast to the adjacent wireless devices 38, 42.

  The wireless device 41 receives the channel change request CHANGE_CHAN3 from the wireless device 36, and receives the channel change request CHANGE_CHAN4 from the wireless device 42. Then, the channel assignment unit 201 of the wireless device 41 determines the network interface NIF2 for the wireless device 36 to perform wireless communication with the wireless device 41 based on the channel change request CHANGE_CHAN3, and the determined network It is detected that the channel Ch2 is allocated to the interface NIF2, and the network interface NIF2 determines the network interface for the wireless device 42 to perform wireless communication with the wireless device 41 based on the channel change request CHANGE_CHAN4. It is detected that the channel Ch2 is assigned to the network interface NIF2 that has been selected.

  Thereafter, the channel assignment unit 201 of the wireless device 41 determines the network interface NIF2 as a network interface for performing wireless communication with the wireless device 36, assigns the channel Ch2 to the determined network interface NIF2, and The network interface NIF2 is determined as a network interface for performing wireless communication with the network 42, and the channel Ch2 is assigned to the determined network interface NIF2.

  Then, the channel assignment unit 201 of the wireless device 41 generates a channel change request CHANGE_CHAN7 = [NIF2 (Ch2) → IPaddress36, IPaddress42 / IPaddress41] indicating the contents of the channel assignment in the wireless device 41, and the generated channel change request CHANGE_CHAN6 = [NIF2 (Ch2) → IPaddress 36, IP address 42 / IP address 41] is broadcast to the adjacent wireless devices 36, 42.

  The wireless device 33 receives the channel change request CHANGE_CHAN2 from the wireless device 38. Then, the channel assignment unit 201 of the wireless device 33 determines the network interface NIF2 as a network interface for the wireless device 38 to perform wireless communication with the wireless device 33 based on the channel change request CHANGE_CHAN2, and determines the determined network. It is detected that the channel Ch2 is assigned to the interface NIF2.

  Thereafter, the channel assignment unit 201 of the wireless device 33 determines the network interface NIF2 as a network interface for performing wireless communication with the wireless device 38, and assigns the channel Ch2 to the determined network interface NIF2.

  Then, the channel assignment unit 201 of the wireless device 33 generates a channel change request CHANGE_CHAN8 = [NIF2 (Ch2) → IPaddress38 / IPaddress33] indicating the contents of channel assignment in the wireless device 33, and the generated channel change request CHANGE_CHAN8 = [ NIF2 (Ch2) → IPaddress38 / IPaddress33] is transmitted to the adjacent wireless device 38.

  The wireless device 31 receives the channel change request CHANGE_CHAN 3 from the wireless device 36. Then, the channel assignment unit 201 of the wireless device 31 determines the network interface NIF2 as a network interface for the wireless device 36 to perform wireless communication with the wireless device 31 based on the channel change request CHANGE_CHAN3, and the determined network It is detected that the channel Ch2 is assigned to the interface NIF2.

  Thereafter, the channel assignment unit 201 of the wireless device 31 determines the network interface NIF2 as a network interface for performing wireless communication with the wireless device 36, and assigns the channel Ch2 to the determined network interface NIF2.

  Then, the channel assignment unit 201 of the wireless device 31 generates a channel change request CHANGE_CHAN9 = [NIF2 (Ch2) → IPaddress36 / IPaddress31] indicating the contents of the channel assignment in the wireless device 31, and the generated channel change request CHANGE_CHAN9 = [ NIF2 (Ch2) → IPaddress36 / IPaddress31] is transmitted to the adjacent wireless device 36.

  The wireless device 37 receives the channel change request CHANGE_CHAN2 from the wireless device 38, receives the channel change request CHANGE_CHAN3 from the wireless device 36, receives the channel change request CHANGE_CHAN4 from the wireless device 42, and receives the channel change request CHANGE_CHAN5 from the wireless device 32. Receive.

  Then, the channel assignment unit 201 of the wireless device 37 determines the network interface NIF1 as a network interface for the wireless device 38 to perform wireless communication with the wireless device 37 based on the channel change request CHANGE_CHAN2, and the determined network Based on the channel change request CHANGE_CHAN3, the wireless device 36 determines that the network interface for performing wireless communication with the wireless device 37 is the network interface NIF1, and detects that the channel Ch1 has been assigned to the interface NIF1. The wireless device 42 detects that the channel Ch1 has been assigned to the network interface NIF1, and the wireless device 42 detects that the wireless device 3 has received the channel change request CHANGE_CHAN4. The network interface NIF1 is determined as a network interface for performing wireless communication with each other, and it is detected that the channel Ch1 is assigned to the determined network interface NIF1, and the wireless device 32 determines that the wireless device 32 is based on the channel change request CHANGE_CHAN5. The network interface NIF2 is determined as a network interface for performing wireless communication with the network 37, and it is detected that the channel Ch2 is allocated to the determined network interface NIF2.

  Further, the wireless device 38 receives the channel change request CHANGE_CHAN 6 from the wireless device 43 and receives the channel change request CHANGE_CHAN 8 from the wireless device 33.

  Then, the channel assignment unit 201 of the wireless device 38 determines the network interface NIF2 as a network interface for the wireless device 43 to perform wireless communication with the wireless device 38 based on the channel change request CHANGE_CHAN6, and the determined network Detecting that channel Ch2 has been assigned to interface NIF2, based on channel change request CHANGE_CHAN8, wireless device 33 determines network interface for wireless communication with wireless device 38 as network interface NIF2, and the determination It is detected that the channel Ch2 is assigned to the network interface NIF2.

  Further, the wireless device 36 receives the channel change request CHANGE_CHAN 7 from the wireless device 41 and receives the channel change request CHANGE_CHAN 9 from the wireless device 31.

  Then, the channel change unit 201 of the wireless device 36 determines the network interface NIF2 as a network interface for the wireless device 41 to perform wireless communication with the wireless device 36 based on the channel change request CHANGE_CHAN7, and the determined network Based on the channel change request CHANGE_CHAN9, it is detected that the network interface for performing wireless communication with the wireless device 36 is determined as the network interface NIF2 based on the channel change request CHANGE_CHAN9. It is detected that the channel Ch2 is assigned to the network interface NIF2.

  Further, the wireless device 42 receives the channel change request CHANGE_CHAN 7 from the wireless device 41 and receives the channel change request CHANGE_CHAN 6 from the wireless device 43.

  Then, the channel changing unit 201 of the wireless device 42 determines the network interface NIF2 as a network interface for the wireless device 43 to perform wireless communication with the wireless device 42 based on the channel change request CHANGE_CHAN6, and the determined network Based on the channel change request CHANGE_CHAN7, it is detected that the network interface for performing wireless communication with the wireless device 42 is determined as the network interface NIF2 based on the channel change request CHANGE_CHAN7. It is detected that the channel Ch2 is assigned to the network interface NIF2.

  Thereby, each of the wireless devices 31 to 33, 36 to 38, and 41 to 43 mutually approves the channel assignment to the network interfaces NIF1 and NIF2 with the adjacent wireless devices.

  And each of the radio | wireless apparatuses 31-33, 36-38, 41-43 performs radio | wireless communication between adjacent radio | wireless apparatuses using the allocated channel.

  As a result of the channel assignment in the radio apparatuses 31 to 33, 36 to 38, and 41 to 43 being performed by the method described above, the channels in the radio apparatuses 31 to 33, 36 to 38, and 41 to 43 are as shown in FIG. Assigned.

  Then, each of the wireless devices 36 to 38 and 42 that are MPRs allocates the channel Ch1 that is the minimum interference channel Ch_ITF_MIN with the least radio wave interference for wireless communication performed with the wireless device that is the MPR, and the minimum interference channel A channel other than Ch_ITF_MIN (= channel Ch2) is allocated for wireless communication with the wireless device that has requested the packet retransmission.

  FIG. 9 is a flowchart for explaining the channel assignment operation in the radio apparatus which is the MPR. When a series of operations is started, the channel assignment unit 201 of the wireless device which is an MPR determines whether or not the assignment of the channels Ch1 and Ch2 to all the network interfaces NIF1 and NIF2 has been completed (step S1).

  When it is determined in step S1 that the assignment of the channels Ch1 and Ch2 to all the network interfaces NIF1 and NIF2 is completed, the channel assignment unit 201 of the wireless device that is an MPR sends the two network interfaces NIF1 and NIF2. The allocation of the channels Ch1 and Ch2 is maintained (step S2).

  On the other hand, when it is determined in step S1 that the assignment of the channels Ch1 and Ch2 to all the network interfaces NIF1 and NIF2 has not been completed, the channel assignment unit 201 of the wireless device that is an MPR has two network interfaces NIF1, It is further determined whether or not the assignment of the channel Ch1 to one network interface NIF1 of the NIF2 is completed (step S3).

  Then, when it is determined in step S3 that the assignment of the channel Ch1 to one network interface NIF1 is not completed, the channel assignment unit 201 of the wireless device that is an MPR is connected to the wireless device that is an adjacent MPR. The channel Ch1 is assigned to the network interface NIF1 for performing wireless communication (step S4).

  Thereafter, the channel assignment means 201 of the wireless device that is an MPR assigns the channel Ch2 to the network interface NIF2 for performing wireless communication with the wireless device other than the adjacent MPR (step S5).

  On the other hand, when it is determined in step S3 that the assignment of the channel Ch1 to one network interface NIF1 is completed, the channel assignment unit 201 of the wireless device that is an MPR wirelessly communicates with a wireless device that is an adjacent MPR. The assignment of channel Ch1 to network interface NIF1 for communication is maintained (step S6).

  Then, the channel assignment unit 201 of the wireless device that is an MPR assigns the channel Ch2 to another network interface NIF2 (step S7).

  Then, after step S5 or step S7, the channel assignment means 201 of the wireless device which is an MPR generates a channel change request CHANGE_CHAN indicating the contents of channel assignment in itself, and the generated wireless device changes the CHANGE_CHAN. (Step S8). And a series of operation | movement is complete | finished after step S2 or step S8.

  In the channel assignment described with reference to FIG. 8, the channel assignment means 201 of the wireless device 37, which is an MPR, first assigns the channels Ch1 and Ch2 to the network interfaces NIF1 and NIF2, and therefore steps S1, S3 to S3 shown in FIG. Channels Ch1 and Ch2 are assigned to the network interfaces NIF1 and NIF2 according to S5 and S8, respectively, and a channel change request CHANGE_CHAN1 indicating the contents of channel assignment in the wireless device 37 is generated and broadcast to adjacent wireless devices 32, 36, 38, and 42. To do.

In addition, the wireless device 38 which is an MPR receives the channel change request CHANGE_CHAN1 from the wireless device 37 and assigns the channel Ch1 to the network interface NIF1, and then the back-off time b (c ₃₈ , m ₃₈ ) calculated by itself expires. In this case, the channel Ch1 assigned to the network interface NIF1 is maintained according to steps S1, S3, S6 to S8 shown in FIG. 9, and the channel Ch2 is assigned to the network interface NIF2, and the channel indicating the contents of the channel assignment in the radio device 38. A change request CHANGE_CHAN2 is generated and broadcast to adjacent wireless devices 33, 37, and 43.

The channel assignment means 201 of the wireless devices 36 and 42 also receives the channel change request CHANGE_CHAN1 from the wireless device 37 and assigns the channel Ch1 to the network interface NIF1, and then calculates the back-off time b (c ₃₆ , m ₃₆ ), b (c ₄₂ , m ₄₂ ), when it expires, the same operation as the channel allocation means 201 of the wireless device 38 is performed.

  FIG. 10 is a flowchart for explaining the operation of the radio apparatus that has received the channel change request CHANGE_CHAN. When a series of operations is started, the channel assignment unit 201 of the wireless device determines whether or not it has received a channel change request CHANGE_CHAN from its own MPR or the wireless device that has requested its own retransmission of a packet (step S11). ).

  When it is determined in step S11 that the channel change request CHANGE_CHAN has not been received, the series of operations ends.

  On the other hand, when it is determined in step S11 that the channel change request CHANGE_CHAN has been received, the channel assignment unit 201 of the wireless device further determines whether or not the channel change request CHANGE_CHAN has been received first (step S12).

  When it is determined in step S12 that the channel change request CHANGE_CHAN is received first, the channel assignment unit 201 of the wireless device assigns a channel included in the channel change request CHANGE_CHAN to one network interface NIF1 (step S13). .

  On the other hand, when it is determined in step S12 that the channel change request CHANGE_CHAN is not received first, the channel assignment unit 201 of the wireless device maintains the already assigned channel and is included in the channel change request CHANGE_CHAN. To be assigned to the other network interface NIF2 (step S14).

  Then, after step S13 or step S14, the channel assignment means 201 of the wireless device updates the neighbor table NTBL for the transmission source of the channel change request CHANGE_CHAN (step S15), and the channel change request CHANGE_CHAN indicating the contents of the channel assignment in itself. And broadcast to neighboring wireless devices (step S16).

  Then, after “NO” in step S11 or step S16, the series of operations ends.

In the channel assignment described in FIG. 8, the wireless device 41 has been described as allocating the channels Ch1 and Ch2 to its network interfaces NIF1 and NIF2 after receiving the channel change request CHANGE_CHAN3 and the channel change request CHANGE_CHAN4. Depending on the length of the calculated back-off time b (c ₄₁ , m ₄₁ ), the channel change request CHANGE_CHAN 3 may be received before the back-off time b (c ₄₁ , m ₄₁ ) expires.

  In such a case, the channel allocation unit 201 of the wireless device 41 performs wireless communication between the wireless device 41 and the wireless device 36 based on the channel change request CHANGE_CHAN3 according to steps S11, S12, S13, S15, and S16 illustrated in FIG. The channel Ch2 is assigned to the network interface NIF2 for performing communication, and the neighbor list for the wireless device 36 that is the transmission source of the channel change request CHANGE_CHAN3 is updated, and only the channel Ch2 for performing wireless communication with the wireless device 36 A channel change request CHANGE_CHAN indicating that the channel is assigned is generated and transmitted to the adjacent wireless device 36.

  Further, the channel assignment means 201 of the wireless device 41 may receive the channel change request CHANGE_CHAN4 from the wireless device 42 after assigning the channel Ch2 to the network interface NIF2 based on the channel change request CHANGE_CHAN3.

  In such a case, the channel assignment unit 201 of the wireless device 41 performs wireless communication between the wireless device 41 and the wireless device 42 based on the channel change request CHANGE_CHAN4 according to steps S11, S12, S14, S15, and S16 illustrated in FIG. The channel Ch2 is assigned to the network interface NIF2 for performing communication, the neighbor list for the wireless device 42 that is the transmission source of the channel change request CHANGE_CHAN4 is updated, and the channel Ch2 for performing wireless communication with the wireless device 36 A channel change request CHANGE_CHAN indicating that the channel Ch2 for performing wireless communication with the wireless device 42 is allocated is generated and transmitted to the adjacent wireless devices 36 and 42.

  FIG. 11 is a diagram illustrating an example of the neighbor list NTBL. When channel assignment is performed in accordance with steps S11, S12, S13, S15, and S16 shown in FIG. 10, channel assignment means 201 of wireless device 41 initially holds neighbor list BTBL-1 (see FIG. 11A). is doing.

  When the channel assignment unit 201 of the wireless device 41 assigns the channel Ch2 to the network interface NIF2 for performing wireless communication with the wireless device 36 (see step S13 in FIG. 10), the wireless device 36 is assigned to the adjacent wireless device. Is registered in the neighbor list NTBL-1, and the neighbor list NTBL-1 is updated to the neighbor list NTBL-2 (see FIG. 10B).

  In addition, the channel assignment unit 201 of the wireless device 41, when performing channel assignment according to steps S11, S12, S14, S15, and S16 shown in FIG. 10, first starts with the neighbor list BTBL-2 (see FIG. 11B). Holding.

  When the channel assignment unit 201 of the wireless device 41 assigns the channel Ch2 to the network interface NIF2 for performing wireless communication with the wireless device 42 (see step S14 in FIG. 10), the wireless device 42 is assigned to the adjacent wireless device. Is registered in the neighbor list NTBL-2, and the neighbor list NTBL-2 is updated to the neighbor list NTBL-3 (see FIG. 10C).

  The channel allocation means 201 of the radio apparatuses 31, 32, 33, 43 also performs channel allocation and neighbor list update according to the flowchart shown in FIG.

  The wireless devices 34, 35, 39, 40, 44, and 45 to 55 also perform channel assignment and neighbor list update by the method described above.

  The characteristics of the wireless network 100 when channel assignment is performed by the above-described method will be described. In the model used for the evaluation of characteristics, 60 wireless devices were randomly arranged on a 9 × 9 grid network, and the wireless communication range was fixed to 10 m with respect to a 100 m × 100 m plane. As a result, each wireless device can communicate with an adjacent wireless device within 4 hops.

  In such a wireless network, the average number of channels used and the maximum throughput when each wireless device performed channel assignment were examined.

  FIG. 12 is a diagram illustrating the average number of channels used by wireless devices arranged in a mesh shape. In FIG. 12, the horizontal axis represents the topology, and the vertical axis represents the average number of used channels. A curve k1 indicates the average number of channels used when channel allocation is performed by the method according to the present invention, a curve k2 indicates the average number of channels used when single channel allocation is performed, and a curve k3 indicates the network interface. The average number of channels used when two channels equal to the number of channels are allocated is shown.

  From the results shown in FIG. 12, when single channel assignment is performed, the average number of used channels is “1”, and when two channels are assigned, the average number of used channels is “2”. On the other hand, when channel allocation is performed by the method according to the present invention, the average number of channels used is between 1.5 and 2.0.

  FIG. 13 is a diagram illustrating the maximum throughput per wireless device in a wireless network including wireless devices arranged in a mesh shape. In FIG. 13, the vertical axis represents the maximum throughput, and the horizontal axis represents the topology. Curve k4 shows the maximum throughput when channel allocation is performed by the method according to the present invention, curve k2 shows the maximum throughput when single channel allocation is performed, and curve k3 allocates two channels. Shows the maximum throughput.

  From the results shown in FIG. 13, the maximum throughput becomes maximum when channel assignment is performed by the method according to the present invention.

  Therefore, the maximum throughput can be improved by performing channel assignment by the method according to the present invention.

As described above, in the present invention, when the wireless network 100 including the wireless devices 31 to 55 arranged in a mesh shape is activated, the wireless devices 36 to 40 and 42 that are MPRs among the wireless devices 31 to 55. , 44, 46 to 50 calculate the back-off time b (c _i , m _i ) depending on the number c _{i of} wireless devices that have requested retransmission of packets to themselves and the number m _i of MPRs adjacent to the wireless device. Then, channel assignment is performed in order of the calculated back-off time b (c _i , m _i ). The back-off time b (c _i , m _i ) becomes shorter as the number c _{i of} wireless devices that have requested the retransmission of the packet by itself increases or as the number m _{i of} MPRs adjacent to the device increases. Probability increases.

Therefore, performing channel assignment in the order of short back-off time b (c _i , m _i ) means that the number of wireless devices that have requested the retransmission of the packet is the largest and / or the number of adjacent MPRs is large. This corresponds to channel assignment in order.

  In the above description, the wireless network 100 is described as including a wireless device including an MPR that first performs channel assignment, and a wireless device other than the MPR that receives a channel change request from the MPR and performs its own channel assignment. However, in the present invention, the present invention is not limited to this, and the wireless network according to the present invention determines a priority for performing channel allocation between each other, and performs a plurality of first allocations in which channels are allocated in descending order of the determined priority. And a plurality of second wireless devices that perform channel allocation in response to a channel change request from at least one of the plurality of first wireless devices. In addition, the priority among the plurality of first wireless devices may be determined by the user of the wireless network 100 and may be preset in the plurality of first wireless devices as an initial setting. That is, wireless network 100 according to the present invention assigns channels in response to channel change requests from a plurality of first wireless devices that perform channel assignment in descending order of priority and at least one of the plurality of first wireless devices. What is necessary is just to provide the some 2nd radio | wireless apparatus to perform.

  If the plurality of first wireless devices and the plurality of second wireless devices are provided, the plurality of first wireless devices perform channel assignment in order, and then the plurality of second wireless devices include the plurality of first wireless devices. This is because channel assignment is performed in response to a channel change request from at least one of the wireless devices, so that a plurality of wireless devices constituting the wireless network do not perform channel assignment in parallel.

  In the above description, the wireless devices 31 to 55 are described as being arranged in a mesh shape. However, the present invention is not limited to this, and the wireless devices 31 to 55 may be disposed in any form. Good.

  Further, in the above description, the number of channels and the number of network interfaces have been described as two. However, the present invention is not limited to this, and the number of channels and the number of network interfaces is three or more. Generally, it may be two or more. In this case, one channel is assigned to one network interface. The number of channels is not necessarily the same as the number of network interfaces.

  In the present invention, the wireless devices 36 to 40, 42, 44, 46 to 50 relay a packet to all the wireless devices 31 to 55 constituting the wireless network 100 with the minimum necessary number of relays. Is configured.

  The wireless devices 36 to 40, 42, 44, 46 to 50 constitute “a plurality of first wireless devices”, and the wireless devices 31 to 35, 41, 43, 45, and 51 to 55 2nd radio | wireless apparatus "is comprised.

  Further, in the present invention, the channel change request CHANGE_CHAN constitutes a “channel allocation request”.

  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 that can easily execute channel assignment.

1 is a schematic diagram of a wireless network according to an embodiment of the present invention. It is a schematic block diagram which shows the structure of the radio | wireless apparatus shown in FIG. It is a block diagram of a packet in the OLSR protocol. It is a block diagram of the routing table shown in FIG. It is the schematic which shows the structure of a neighbor list. It is a functional block diagram of channel allocation in each wireless device. It is a figure which shows the MPR set in a wireless network. It is a figure for demonstrating in detail the method of channel allocation. It is a flowchart for demonstrating the operation | movement of the channel allocation in the radio | wireless apparatus which is MPR. 6 is a flowchart for explaining an operation of a wireless device that has received a channel change request. It is a figure which shows the example of a neighbor list. It is a figure which shows the average number of channels used by the radio | wireless apparatus arrange | positioned at mesh form. It is a figure which shows the maximum throughput per radio | wireless apparatus in the radio | wireless network which consists of the radio | wireless apparatus arrange | positioned at mesh form.

Explanation of symbols

  10, 11, 61-85 antenna, 12 input unit, 13 output unit, 14 user application, 15 communication control unit, 16 wireless interface module, 17 MAC module, 18 buffer, 19 LLC module, 20, 20A IP module, 21 routing Table, 22 TCP module, 23 UDP module, 24 routing daemon, 31-55 wireless device, 100 wireless network, 201 channel allocation means, 202 timer.

Claims (12)

A wireless network established autonomously,
A plurality of first wireless devices that perform channel assignment in descending order of priority;
A wireless network comprising: a plurality of second wireless devices that perform channel assignment in response to a channel assignment request from at least one of the plurality of first wireless devices.   The wireless network according to claim 1, wherein the plurality of first wireless devices determine the priority among each other.   3. The wireless network according to claim 1, wherein each of the plurality of second wireless devices performs the channel assignment according to a channel assignment result in the first wireless device accessed by the plurality of second wireless devices.   2. Each of the plurality of first wireless devices is a wireless device included in a relay wireless device group that relays a packet to all the wireless devices configuring the wireless network with a minimum number of relays. The wireless network according to claim 3.   The wireless network according to any one of claims 1 to 4, wherein the plurality of first wireless devices exist in the same communication range.   The wireless network according to any one of claims 1 to 5, wherein the plurality of first wireless devices perform the channel assignment in the order in which a random back-off time given to each wireless device has elapsed.   The plurality of first wireless devices allocate the channel in order of increasing number of wireless devices that request the relay of the packet and / or the number of wireless devices included in the relay wireless device group among neighboring wireless devices. The wireless network according to claim 1, wherein the wireless network is performed.   Each of the plurality of first wireless devices allocates a minimum interference channel with the smallest radio wave interference as a channel used for communication with wireless devices included in the relay wireless device group, and relays packets to other channels by itself. 6. The wireless network according to claim 4, wherein the wireless network is assigned as a channel used for communication with a requesting wireless device.   9. The wireless network according to claim 8, wherein each of the plurality of first wireless devices detects the minimum interference channel by exchanging information with a wireless device existing within a two-hop region from itself.   Each of the plurality of first wireless devices has a plurality of interfaces, and when channel assignment is not performed for all of the plurality of interfaces, mutually different channels are assigned to the plurality of interfaces. When channel assignment is completed for some of the plurality of interfaces, a channel different from the channel assigned to the interface for which channel assignment has been completed is assigned to an interface for which channel assignment has not been completed. The wireless network according to claim 4 or 5, wherein the wireless network is assigned.   Each of the plurality of first wireless devices maintains a channel of the interface for which the channel assignment is completed when channel assignment is completed for some of the plurality of interfaces. The wireless network according to 10.   Each of the plurality of first wireless devices has a plurality of interfaces, and a channel used for communication with the wireless devices included in the relay wireless device group is allocated to all of the plurality of interfaces. 6. The wireless network of claim 4 or claim 5, wherein the wireless network maintains channels assigned to the plurality of interfaces.

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