JP2008301138A - Communication system, wireless communication node, address management device, and communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce communication interruption time due to network structure changes if a wireless terminal communicates with a wireless base station through other wireless terminals to access a cable network, such as the Internet. <P>SOLUTION: The wireless terminal UT has a storage part 406 which stores a routing information table (RA table) in which an IP address directly assigned to its own node or IP addresses assigned to lower wireless terminals connected through relay nodes are linked to routing information (RA) used for relaying packets to the lower wireless terminals, and a packet relay part 404 which relays the packets to the lower wireless terminals based on the routing information (RA) in the routing information table. The routing information (RA) includes identifiers of the lower wireless terminals and relay nodes. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention configures an address management device that is connected to a wired network and manages an address used to access the wired network, and a tree-structured network in which an address is assigned by the address management device and the address management device is the highest level. The present invention relates to a communication system including a plurality of wireless communication nodes, a wireless communication node used in the communication system, an address management device, and a communication method.

  There is known an ad hoc network which is a wireless network autonomously configured by a plurality of wireless communication nodes having a packet relay function. Further, a technique has been proposed in which a wireless terminal communicates with a wireless base station using an ad hoc network (see, for example, Patent Document 1). Specifically, the wireless terminal communicates with the wireless base station via another wireless terminal.

  That is, a tree-structured network having a wireless base station as the highest node is configured by a plurality of wireless terminals. Since the wireless terminal communicates with the wireless base station via another wireless terminal, the wireless terminal can communicate with the wireless base station even if the wireless terminal is outside the radio wave reachable range of the wireless base station.

There is also provided a communication system in which a wireless terminal can access the Internet via a wireless base station. In such a communication system, when a wireless terminal accesses the Internet, the address management device dynamically assigns an IP address to the wireless terminal. The wireless terminal accesses the Internet using the IP address assigned by the address management device.
Japanese Patent Laid-Open No. 2003-124876 (page 6-7, FIG. 7)

  However, when a wireless terminal accesses the Internet using the above-described ad hoc network, there are the following problems. Specifically, when a wireless terminal configuring the ad hoc network moves, the network configuration of the ad hoc network is changed.

  The above-described address management device needs to reassign an IP address to a wireless terminal related to the change of the network configuration every time the network configuration of the ad hoc network is changed. For this reason, the wireless terminal related to the change in the network configuration has a problem that communication is interrupted until a new IP address is assigned.

  Furthermore, if the address management device reassigns an IP address to the wireless communication node each time the network configuration of the ad hoc network is changed, there is a problem that the load on the address management device increases.

  Therefore, the present invention has been made to solve the above-described problem, and when a wireless terminal accesses a wired network such as the Internet by communicating with a wireless base station via another wireless terminal, the network Provided are a communication system, a wireless communication node used in the communication system, an address management device, and a communication method capable of reducing a period during which communication is interrupted in a wireless terminal related to the configuration change and reducing the load on the address management device. For the purpose.

  In order to achieve the above object, a first feature of the present invention is that an address management device (IP address) is connected to a wired network (Internet 100) and manages an address (IP address) used to access the wired network. A management apparatus ARN) and a communication provided with a plurality of radio communication nodes (radio base station BS, radio terminal UT) which are assigned addresses by the address management apparatus and constitute a tree-structured network with the address management apparatus as the highest level. The wireless communication node includes a relay node (wireless terminal UT) that relays a packet (packet) including an address assigned by the address management device, and a base station node (directly connected to the address management device). Radio base station BS), and the address management device includes the Base station information in which a base station identifier (base station address) for identifying a ground station node is associated with an address assigned to a wireless communication node (wireless terminal UT) connected to the base station node directly or via a relay node A base station information table storage unit (storage unit 205) that stores a table, and a first packet relay unit that relays a packet to the base station node based on the base station identifier in the stored base station identifier table ( A packet relay unit 203), and the wireless communication node relays an address assigned to a lower wireless communication node connected to the own node directly or via the relay node and a packet to the lower wireless communication node A route information table storage unit (storage) that stores a route information table (RA table) in association with route information (RA) used for 306 or storage unit 406) and a second packet relay unit (packet relay unit 304 or packet relay unit 404) that relays a packet to the lower-layer wireless communication node based on the route information in the stored route information table. And the route information includes a node identifier of the lower radio communication node and a node identifier of a relay node on a communication route between the own node and the lower radio communication node. To do.

  According to such a feature, the address management device can perform base station identification based on the base station identifier associated with the address assigned to the lower radio communication node in the base station identifier table stored in the base station information table storage unit. Relay the packet to the station node. The wireless communication node relays the packet to the lower wireless communication node based on the route information in the route information table stored in the route information table. The path information includes the node identifier of the lower-layer wireless communication node and the node identifier of the relay node on the communication path between the own node and the lower-layer wireless communication node.

  That is, the packet relay destination can be specified based on the base station identifier or the node identifier, and the address management device assigns an IP address to the wireless terminal related to the network configuration change even if the network configuration of the ad hoc network is changed. There is no need to fix it. Further, the radio base station and the radio terminal that relay the packet can easily identify the radio terminal that must relay to transmit the packet to the radio terminal that is the destination of the packet, from the path information stored in the path information table. . Therefore, when a wireless terminal accesses a wired network such as the Internet by communicating with a wireless base station via another wireless terminal, communication by IP address reassignment or route search in the wireless terminal related to the network configuration change It is possible to provide a communication system capable of reducing the period during which the address is interrupted and reducing the load on the address management device.

  A second feature of the present invention is that a plurality of wireless communication nodes constituting a tree-structured network in which an address is assigned by an address management device that manages an address used for accessing a wired network and the address management device is the highest level An address assigned to a lower-layer wireless communication node connected to the own node directly or via a relay node, and path information used for relaying a packet to the lower-layer wireless communication node. A route information table storage unit that stores the associated route information table, and a packet relay unit that relays a packet to the lower wireless communication node based on the route information in the stored route information table, The path information includes a node identifier of the subordinate radio communication node, and the own node and the And gist comprises a node identifier of a relay node on a communication path between the position of the wireless communication nodes.

  A third feature of the present invention relates to the third feature of the present invention, wherein the packet relay unit acquires a route information corresponding to an address included in the packet from the route information table (packet relay unit). Unit 304 or packet relay unit 404) and a node identifier acquisition unit that acquires a node identifier of a wireless communication node that is directly connected to the own node from among the node identifiers included in the route information acquired by the route information acquisition unit ( Packet relay unit 304 or packet relay unit 404) and a packet transmission unit (packet relay unit 304 or packet relay unit 404) that transmits a packet to the wireless communication node indicated by the node identifier acquired by the node identifier acquisition unit. This is the gist.

  A fourth feature of the present invention relates to the second feature of the present invention, and is a connection for transmitting a first connection request (connection request message) for requesting connection to an upper wireless communication node to the upper wireless communication node. A request transmission unit (message processing unit 305 or message processing unit 405), and the connection request transmission unit includes an address (CalledIPAddress) that is allocated when an address is allocated by the address management device. The gist is to transmit one connection request to the upper wireless communication node.

  A fifth feature of the present invention relates to the fourth feature of the present invention, and is a first connection request for receiving a second connection request (connection request message) for requesting direct connection to the own node from a lower-layer wireless communication node. When the receiving unit (message processing unit 305 or message processing unit 405) and the first connection request receiving unit receive the second connection request, a node identifier is assigned to the wireless communication node that has transmitted the second connection request. An identifier assigning unit (message processing unit 305 or message processing unit 405) and a node identifier notifying unit (message processing unit) for notifying the upper wireless communication node of the second connection request including the node identifier assigned by the identifier assigning unit. 305 or a message processing unit 405).

  A sixth feature of the present invention relates to the sixth feature of the present invention, and is a second connection request receiving unit (message processing) that receives a third connection request (connection request message) including a node identifier (SourceTreeAddress) from a relay node. Unit 305 or message processing unit 405) and a route for updating the route information table according to a node identifier included in the third connection request when the second connection request receiving unit receives the third connection request. The gist is to further include an information table update unit (RA table management unit 303 or RA table management unit 403).

  According to a seventh aspect of the present invention, there is provided an address management apparatus for allocating addresses used for accessing a wired network to a plurality of wireless communication nodes and managing the allocated addresses, wherein a base connected directly to the address management apparatus A base station information table storage unit for storing a base station information table in which a base station identifier for identifying a station node is associated with an address assigned to a wireless communication node connected to the base station node directly or via a relay node; And a packet relay unit that relays a packet to the base station node based on the base station identifier in the stored base station identifier table.

  According to an eighth aspect of the present invention, there is provided an address management device that is connected to a wired network and manages an address used for accessing the wired network, and an address assigned by the address management device, wherein the address management device is the highest level. A plurality of wireless communication nodes constituting the tree-structured network, wherein the wireless communication node is directly connected to the relay node that relays a packet including an address assigned by the address management device, and the address management device A communication method used for a communication system including a base station node, wherein the address management device connects a base station identifier for identifying the base station node, and the base station node directly or via a relay node Base station information table associating addresses assigned to communication nodes A storing step (step S204), an address assigned to a lower wireless communication node to which the wireless communication node is connected directly or via a relay node, and a relay of a packet to the lower wireless communication node A step of storing a route information table in association with route information used for the base station (step S408), and the address management device based on the base station identifier in the stored base station identifier table Relaying the packet to the node (steps S101 to S104), and the wireless communication node relaying the packet to the lower-layer wireless communication node based on the route information in the stored route information table (Step S301 to Step S304), and the route information Node identifier of position of the wireless communication nodes, and the gist comprises a node identifier of a relay node on a communication path between the own node and the subordinate wireless communication nodes.

  According to the present invention, when a wireless terminal accesses a wired network such as the Internet by communicating with a wireless base station via another wireless terminal, the period during which communication is interrupted in the wireless terminal related to the network configuration change And a communication system capable of reducing the load on the address management device, a wireless communication node used in the communication system, an address management device, and a communication method can be provided.

  Next, an embodiment of the present invention will be described with reference to the drawings. In the description of the drawings in the following embodiments, the same or similar parts are denoted by the same or similar reference numerals.

  In the following, (1) the configuration of the communication system, (2) the operation of the communication system, (3) the operation example of the communication system, (4) the operation and effect, and (5) other embodiments will be described in this order. .

(1) Configuration of Communication System First, the configuration of the communication system according to the present embodiment will be described with reference to FIGS.

(1.1) Overall Schematic Configuration FIG. 1 is an overall schematic configuration diagram of a communication system according to the present embodiment. As shown in FIG. 1, the communication system includes the Internet 100, an IP address management device ARN, a plurality of radio base stations BS, and a plurality of radio terminals UT.

  In the example of FIG. 1, a tree structure network having the IP address management device ARN as the highest layer (root node) is configured by the radio base station BS and the radio terminal UT.

  The IP address management device ARN is connected to the Internet 100 and manages an IP address used for accessing the Internet 100. The radio base station BS is directly connected to the IP address management device ARN. The wireless terminal UT accesses a communication destination device such as a server on the Internet 100 using the IP address assigned by the IP address management device ARN.

  The radio terminal UT in the lowest layer communicates (multi-hop communication) with the radio base station BS via the radio terminal UT with the radio base station BS. That is, an ad hoc network is configured in the wireless terminal UT.

(1.2) Detailed Configuration of Communication System Next, a detailed configuration of the communication system described above will be described. Specifically, (1.2.1) Configuration of IP address management device, (1.2.2) Configuration of radio base station, (1.2.3) Configuration of radio terminal, (1.2.4) ) Explain the structure of the message.

(1.2.1) Configuration of IP Address Management Device Next, the configuration of the IP address management device ARN will be described. FIG. 2 is a functional block diagram showing the configuration of the IP address management device ARN.

  As shown in FIG. 2, the IP address management device ARN includes a wired communication I / F unit 201, a base station address table management unit 202, a packet relay unit 203, a message processing unit 204, and a base station address table storage unit 205.

  The wired communication I / F unit 201 functions as an interface with the Internet 100 and an interface with the radio base station BS.

  The base station address table management unit 202 manages the base station address table stored in the base station address table storage unit 205. The base station address table is a table in which the IP address of the wireless terminal UT is associated with the base station address of the wireless base station BS to which a packet addressed to the wireless terminal UT is to be transferred (see FIGS. 12 to 23).

  The packet relay unit 203 relays a packet from the Internet 100 to the radio base station BS, or relays a packet from the radio base station BS to the Internet 100 based on the base station address table.

  In the above-described tree structure network, no branching occurs in the upstream direction (the direction from the wireless terminal UT to the Internet 100). For this reason, the packet relay unit 203 uses the base station address table in relaying packets in the downlink direction (direction from the Internet 100 toward the wireless terminal UT).

  The message processing unit 204 processes a connection request message received from the radio terminal UT via the radio base station BS and a route search message transmitted to the radio terminal UT via the radio base station BS. Details of the connection request message and the route search message will be described later.

(1.2.2) Configuration of Radio Base Station Next, the configuration of the radio base station BS will be described. FIG. 3 is a functional block diagram showing the configuration of the radio base station BS.

  As illustrated in FIG. 3, the radio base station BS includes a radio processing unit 301, a control unit 302, an RA (Relative Address) table management unit 303, a packet relay unit 304, a message processing unit 305, and a storage unit 306.

  The wireless processing unit 301 transmits and receives wireless signals to and from the wireless terminal UT. In this embodiment, the radio base station BS and the radio terminal UT perform radio communication based on iBurst (registered trademark) (for the iBurst standard, “High Capacity-Spatial Division Multiple Access (HC-SDMA)”, WTSC-2005-032, see ATIS / ANSI). For this reason, the wireless processing unit 301 has a configuration based on iBurst.

  The control unit 302 controls the entire radio base station BS. The control unit 302 has a function of executing various communication protocols.

  The RA table management unit 303 manages the RA table stored in the storage unit 306. The RA is route information and information indicating the position of the wireless terminal UT in the above-described tree structure network. The RA table is a table in which the IP address of the wireless terminal UT is associated with the RA of the wireless terminal UT (see FIGS. 12 to 23).

  Based on the RA table, the packet relay unit 304 relays a packet from the Internet 100 to the wireless terminal UT, and relays a packet from the wireless terminal UT to the Internet 100. The packet relay unit 304 uses the RA table for relaying packets in the downlink direction.

  The message processing unit 305 processes a connection request message received from the wireless terminal UT and a route search message received from the IP address management device ARN.

  The storage unit 306 stores the RA table and the base station address described above.

(1.2.3) Configuration of Radio Terminal Next, the configuration of the radio terminal UT will be described. FIG. 4 is a functional block diagram showing the configuration of the wireless terminal UT.

  As illustrated in FIG. 4, the wireless terminal UT includes a wireless processing unit 401, a control unit 402, an RA table management unit 403, a packet relay unit 404, a message processing unit 405, and a storage unit 406.

  The radio processing unit 401 transmits / receives a radio signal to / from the radio terminal UT or the radio base station BS using the iBurst described above.

  The control unit 402 controls the entire wireless terminal UT. The control unit 402 has a function of executing various communication protocols. The control unit 402 controls switching of the connection destination radio base station BS or radio terminal UT, that is, handover.

  The RA table management unit 403 manages the RA table stored in the storage unit 406.

  The packet relay unit 404 relays the packet to the radio base station BS or the radio terminal UT based on the RA table.

  The message processing unit 405 processes a connection request message received from the wireless terminal UT and a route search message received from the IP address management device ARN.

  The storage unit 406 stores the above-described RA table and own RA.

(1.2.4) Message Structure Next, the structure of the connection request message and the route search message will be described.

  FIG. 5A is a diagram illustrating a configuration of a connection request message. As shown in FIG. 5A, the connection request message has CalledIPAddress and SourceTreeAddress.

  CalledIPAddress is the IP address of the wireless terminal UT that is the transmission source of the connection request message.

  SourceTreeAddress is the RA of the wireless terminal UT that is the transmission source of the connection request message. However, SourceTreeAddress is empty when a connection request message is transmitted to the IP address management device ARN.

  FIG. 5B is a diagram showing the configuration of the route search message. As shown in FIG. 5B, the route search message has SearchIPAddress and TargetTreeAddress.

  SearchIPAddress is the IP address of the wireless terminal UT to be searched for the route search message.

  TargetTreeAddress is the RA of the wireless terminal UT that is the search target of the route search message. However, TargetTreeAddress is empty when transmitted from the IP address management device ARN.

(2) Operation of Communication System Next, the operation of the communication system described above will be described with reference to FIGS. Specifically, (2.1) Operation of IP Address Management Device and (2.2) Operations of Radio Base Station and Radio Terminal will be described.

(2.1) Operation of IP Address Management Device Hereinafter, a packet relay operation and a connection request message reception operation executed by the IP address management device ARN will be described.

(2.1.1) Packet Relay Operation FIG. 6 is a flowchart showing an operation flow of the packet relay operation executed by the IP address management device ARN.

  In step S101, the IP address management device ARN receives a packet from the Internet 100.

  In step S102, the IP address management device ARN extracts an IP address (destination IP address) from the packet received in step S101.

  In step S103, the IP address management device ARN acquires the base station address corresponding to the IP address obtained in step S102 from the base station address table.

  In step S104, the IP address management device ARN transmits the packet received in step S101 to the radio base station BS indicated by the base station address acquired in step S103.

(2.1.2) Connection Request Message Receiving Operation FIG. 7 is a flowchart showing an operation flow of a connection request message receiving operation executed by the IP address management device ARN.

  In step S201, the IP address management device ARN receives a connection request message from the radio terminal UT via the radio base station BS. The IP address management device ARN stores the base station address of the radio base station BS that relayed the connection request message.

  In step S202, the IP address management device ARN determines whether or not CalledIPAddress exists in the connection request message received in step S201. If no CalledIPAddress exists, the process proceeds to step S203.

  In step S203, the IP address management device ARN assigns an IP address to the wireless terminal UT that has transmitted the connection request message. The assigned IP address is transferred to the wireless terminal UT that is the transmission source of the connection request message via the wireless base station BS.

  In step S204, the IP address management device ARN registers the IP address assigned in step S203 and the base station address stored in step S201 in association with each other in the base station address table.

(2.2) Operations of Radio Base Station and Radio Terminal Hereinafter, packet relay operations and connection request message reception operations executed by the radio base station BS and the radio terminal UT will be described.

(2.2.1) Packet Relay Operation of Radio Base Station and Radio Terminal FIG. 8 is a flowchart showing an operation flow of a packet relay operation executed by the radio base station BS and the radio terminal UT. Since the packet relay operation is executed in the same manner in the radio base station BS and the radio terminal UT, the operation of the radio base station BS will be described here as an example.

  In step S301, the radio base station BS receives a packet from an upper node (here, the IP address management device ARN).

  In step S302, the radio base station BS extracts an IP address (destination IP address) from the packet received in step S301.

  In step S303, the radio base station BS acquires an RA corresponding to the IP address obtained in step S302 from the RA table.

  In step S304, the radio base station BS transmits the packet received in step S301 to the radio terminal UT indicated by the RA acquired in step S303. At this time, the radio base station BS transmits the RA acquired in step S303 in addition to the packet.

(2.2.2) Connection Request Message Reception Operation of Radio Base Station FIG. 9 is a flowchart showing an operation flow of a connection request message reception operation including a Called IP Address executed by the radio base station BS and the radio terminal UT. In the radio base station BS and the radio terminal UT, the connection request message reception operation is performed in the same manner, and therefore, the operation of the radio base station BS will be described as an example here.

  In step S401, the radio base station BS extracts the Called IP Address and the Source Tree Address from the connection request message.

  In step S402, the radio base station BS determines whether the Called IP Address extracted in step S401 exists in the RA table. If CalledIPAddress exists in the RA table, the process proceeds to step S403. If CalledIPAddress does not exist in the RA table, the process proceeds to step S407.

  In step S403, the radio base station BS determines whether or not the RA corresponding to the Called IP Address extracted in step S401 matches the Source Tree Address extracted in step S401. If the RA and SourceTreeAddress match, the process proceeds to step S409. If the RA and SourceTreeAddress are different, the process proceeds to step S404.

  In step S404, the radio base station BS has a lower node (child node) in the radio terminal UT that is the transmission source of the connection request message, and whether or not the IP address of the lower node (child node) is stored in the RA table. Determine whether. If the IP address of the lower node is stored in the RA table, the process proceeds to step S405. If the IP address of the lower node is stored in the RA table, the process proceeds to step S406.

  In step S405, the radio base station BS overwrites SourceTreeAddress in the RA of the transmission source node and the lower node. However, the radio base station BS overwrites the lower node RA only for the level (hierarchy) of the transmission source node.

  In step S406, the radio base station BS overwrites the source tree RA with the SourceTreeAddress.

  On the other hand, in step S407, the radio base station BS allocates a new RA to the transmission source node.

  In step S408, the radio base station BS registers CalledIPAddress and SourceTreeAddress in the RA table, assuming that the transmission source node is a new node.

  In step S409, the radio base station BS updates the SourceTreeAddress in the connection request message relayed to the upper node to the level (hierarchy) of the upper node.

  In step S410, the radio base station BS relays the connection request message including the updated SourceTreeAddress to the upper node.

(2.2.3) Route Search Message Reception Operation of Radio Base Station FIG. 10 is a flowchart showing an operation flow of a route search message reception operation executed by the radio base station BS.

  In step S501, the radio base station BS extracts SearchIPAddress from the route search message transmitted by the IP address management device ARN.

  In step S502, the radio base station BS determines whether or not the SearchIPAddress extracted in step S501 matches its own IP address. If the SearchIPAddress matches the own IP address, the process proceeds to step S506. If the SearchIPAddress is different from its own IP address, the process proceeds to step S503.

  In step S503, the radio base station BS determines whether or not SearchIPAddress exists in the RA table. If SearchIPAddress exists in the RA table, the process proceeds to step S504. If SearchIPAddress does not exist in the RA table, the process proceeds to step S507.

  In step S504, the radio base station BS updates the TargetTreeAddress to the RA of the entry that matches the SearchIPAddress from the RA table.

  In step S505, the radio base station BS updates TargetTreeAddress in the route search message relayed to the lower node according to the RA level (hierarchy) of the lower node.

  On the other hand, in step S506, the radio base station BS performs reception processing as a message addressed to the radio base station BS and transmits a response.

  Finally, in step S507, the radio base station BS relays the route search message to the lower node.

(2.2.4) Route Search Message Receiving Operation of Wireless Terminal FIG. 11 is a flowchart showing an operation flow of route search message receiving operation executed by the wireless terminal UT. Here, only operations different from those in FIG. 10 will be described, and redundant descriptions will be omitted.

  In step S601, the wireless terminal UT extracts SearchIPAddress and TargetTreeAddress from the route search message.

  In step S603, the wireless terminal UT determines whether or not the SearchIPAddress exists in the RA table. If SearchIPAddress exists in the RA table, the process proceeds to step S605. If the SearchIPAddress does not exist in the RA table, the process proceeds to step S604.

  In step S604, the wireless terminal UT registers SearchIPAddress and TargetTreeAddress in the RA table as new nodes.

(3) Operation Example of Communication System Next, operation examples 1 to 5 of the communication system according to the present embodiment will be described with reference to FIGS.

  Operation example 1 is an operation in which the radio terminal UT performs a handover at a level (hierarchy) immediately below the radio base station BS.

  The operation example 2 is an operation in which the radio terminal UT performs handover at a level (hierarchy) two levels below the radio base station BS.

  The operation example 3 is an operation in which a radio terminal UT having a child node performs a handover at a level (hierarchy) two levels below the radio base station BS.

  The operation example 4 is an operation in which the radio terminal UT performs a handover from a level (hierarchy) two levels below the radio base station BS to a level (hierarchy) just below the radio base station BS.

  The operation example 5 is an operation in which the radio terminal UT performs a handover from a level (hierarchy) immediately below the radio base station BS to a level (hierarchy) two levels below the radio base station BS.

(3.1) Operation example 1
12 and 13 are explanatory diagrams of operation example 1 of the communication system according to the present embodiment. FIG. 12 shows an IP address management device ARN, radio base stations BS1 and BS2, and a radio terminal UT1.

  First, the radio terminal UT1 transmits a connection request to the radio base station BS1. When receiving the connection request, the radio base station BS1 notifies the IP address management device ARN that the connection request has been received.

  The IP address management device ARN assigns an IP address to the wireless terminal UT1. The IP address management device ARN stores the IP address assigned to the radio terminal UT1 and the base station address of the radio base station BS1 in association with each other, and manages which radio base station is under control.

  The radio base station BS1 notifies the radio terminal UT1 of the IP address assigned by the IP address management device ARN. As a result, the wireless terminal UT1 can connect to the Internet 100 using the IP address “172.16.0.1”. Further, the radio base station BS1 allocates RA “1” managed by itself to the radio terminal UT1.

  Thereafter, as shown in FIG. 13, the radio terminal UT1 transmits a connection request including the IP address “172.16.0.1” to the radio base station BS2 in order to switch the connection destination to the radio base station BS2. The radio base station BS2 assigns RA “3” managed by the radio base station BS2 to the radio terminal UT1. The radio base station BS2 transmits a connection request from the radio terminal UT1 to the IP address management device ARN.

  When receiving the connection request from the radio base station BS2, the IP address management device ARN updates the base station address table. Specifically, the IP address management device ARN wirelessly transmits the base station address “192.168.10.109” of the radio base station BS1 corresponding to the IP address “172.16.0.1” of the radio terminal UT1. The base station address of the base station BS2 is updated to “192.168.10.148”. As a result, the IP address management device ARN transfers the packet addressed to the IP address “172.16.0.1” to the radio base station BS2.

  Since the IP address management device ARN transfers the packet addressed to the radio terminal UT1 to the radio base station BS2, the packet addressed to the radio terminal UT1 does not come to the radio base station BS1. Therefore, the radio base station BS1 deletes the information of the radio terminal UT1 from the RA table after a sufficient time has elapsed. As a result, RA can be used repeatedly.

(3.2) Operation example 2
14 and 15 are explanatory diagrams of operation example 2 of the communication system according to the present embodiment.

  In FIG. 14, an IP address management device ARN, radio base stations BS1 and BS2, and a radio terminal UT1 are shown. A radio terminal UT1 and a radio terminal UT2 are connected to the radio base station BS1.

  An IP address “172.16.0.1” is assigned to the wireless terminal UT1 by the IP address management device ARN, and RA “1” is assigned by the wireless base station BS1.

  An IP address “172.16.0.2” is assigned to the wireless terminal UT2 by the IP address management device ARN, and RA “2” is assigned by the wireless base station BS1.

  When the wireless terminal UT3 transmits a connection request to the wireless terminal UT1, the wireless terminal UT1 and the wireless base station BS1 transfer the connection request to the IP address management device ARN. It is assumed that the IP address management device ARN has assigned the IP address “172.16.0.3” to the wireless terminal UT3. In the base station address table, the IP address “172.16.0.3” of the wireless terminal UT3 is associated with the base station address “192.168.10.109” of the wireless base station BS1.

  The radio base station BS1 transfers the IP address “172.16.0.3” of the radio terminal UT3 assigned by the IP address management device ARN to the radio terminal UT1. Also, the radio base station BS1 adds the IP address “172.16.0.3” of the radio terminal UT3 to the RA table managed by the radio base station BS1. At this time, the RA of the radio terminal UT3 is not yet determined in the RA table of the radio base station BS1.

  The wireless terminal UT1 relays the IP address “172.16.0.3” of the wireless terminal UT3 transferred by the wireless terminal UT1 to the wireless terminal UT3. Also, the wireless terminal UT1 assigns RA “1” managed by itself to the wireless terminal UT3. The wireless terminal UT1 associates the IP address “172.16.0.3” of the wireless terminal UT3 with the assigned RA “1” and adds them to the RA table. The radio terminal UT1 notifies the radio base station BS1 that RA “1” has been assigned to the radio terminal UT3.

  When the wireless base station BS1 receives a notification from the wireless terminal UT1 that the RA “1” is assigned to the wireless terminal UT3, the wireless base station BS1 sends the notified RA “1” to the RA “1” of the wireless terminal UT1 assigned by the wireless base station BS1. RA “1.1” is created by linking. The created RA “1.1” is associated with the IP address “172.16.0.3” of the wireless terminal UT3 and stored in the RA table.

  Thereafter, the wireless terminal UT3 moves and switches the connection destination to the wireless terminal UT2, as shown in FIG. Specifically, the wireless terminal UT3 transmits a connection request including its own assigned IP address “172.16.0.3” to the wireless terminal UT2.

  The radio terminal UT2 transfers the connection request transmitted by the radio terminal UT3 to the radio base station BS1.

  The radio terminal UT2 assigns RA “3” to the radio terminal UT3 and stores the IP address “172.16.0.3” and RA “3” of the radio terminal UT3 in the RA table managed by the radio terminal UT2. Also, the radio terminal UT2 transfers to the radio base station BS1 a message indicating that RA “3” has been assigned to the radio terminal UT3, and transfers it.

  The wireless base station BS1 recognizes that the IP address “172.16.0.3” of the wireless terminal UT3 is already registered, and does not transfer the connection request to the IP address management device ARN. Further, the radio base station BS1 detects that the radio terminal UT3 connected to the radio terminal UT1 has switched the connection destination to the radio terminal UT2, and notifies the radio terminal UT2 that it has already been authenticated. At this time, the wireless terminal UT1 may delete the RA of the wireless terminal UT3 in the RA table managed by itself.

  The wireless base station BS1 recognizes that the IP address “172.16.0.3” of the wireless terminal UT3 has become RA “3” under the control of RA “2”, and sets the RA table managed by itself to the RA “ Update to 2.3 ".

  Thereafter, the radio base station BS1 and the radio terminal UT2 transfer a packet addressed to the radio terminal UT3. At this time, the radio base station BS1 transfers the packet addressed to the radio terminal UT3 to RA “2”, that is, the radio terminal UT2 by referring to the RA table.

  The wireless terminal UT1 deletes the information on the wireless terminal UT3 on the RA table managed by the wireless terminal UT1 after a sufficient time has elapsed since the arrival of the packet addressed to the wireless terminal UT3.

(3.3) Operation example 3
16 to 18 are explanatory diagrams of an operation example 3 of the communication system according to the present embodiment.

  In FIG. 16, a radio terminal UT1 and a radio terminal UT2 are connected to the radio base station BS1. A wireless terminal UT3 is connected to the wireless terminal UT1, and a wireless terminal UT4 is connected to the wireless terminal UT3 as a child node.

  Information on the wireless terminal UT1, the wireless terminal UT2, the wireless terminal UT3, and the wireless terminal UT4 is registered in the IP address management device ARN. In the RA table of the radio base station BS1, the radio terminal UT3 is registered as RA “1.1”, and the radio terminal UT4 is registered as RA “1.1.3”.

  Here, it is assumed that the wireless terminal UT3 having a child node moves and switches the connection destination from the wireless terminal UT1 to the wireless terminal UT2, as shown in FIG. At this time, the wireless terminal UT3 transmits to the wireless terminal UT2 a connection request including the already assigned IP address.

  The radio terminal UT2 assigns RA “3” of the RA table managed by itself to the radio terminal UT3 and transfers it to the radio base station BS1 in a connection request from the radio terminal UT3. The radio base station BS1 detects that the IP address of the radio terminal UT3 has already been assigned, erases the RA table of the radio terminal UT3, and erases the table of the radio terminal UT4 under the radio terminal UT3.

  When the radio base station BS1 receives the new RA “3” of the radio terminal UT3 from the radio terminal UT2, the radio base station BS1 assigns the RA corresponding to the IP address “172.16.0.3” of the RA table managed by the radio base station BS1 to the RA “1”. .3 ”is rewritten to RA“ 2.3 ”.

  At the same time, since the information of the wireless terminal UT4 managed by the wireless base station BS1 is originally under the control of the wireless terminal UT3, the RA of the wireless terminal UT3 is rewritten to “2.3”, and the RA of the wireless terminal UT4 is also “2.3. Rewrite to 3 ”.

  On the other hand, the radio terminal UT4 does not know that the radio terminal UT3, which is an upper node, has moved from the radio terminal UT1 to the radio terminal UT2. Also, the wireless terminal UT2 does not know that the wireless terminal UT4 exists under the wireless terminal UT3.

  When the wireless terminal UT4 transmits a packet in the direction of the IP address management device ARN, or when a route search message or packet from the IP address management device ARN passes through the wireless base station BS1 and the wireless terminal UT2, as shown in FIG. The wireless terminal UT2 knows that the wireless terminal UT4 is under the control of the wireless terminal UT3 and that RA “3” is assigned to the wireless terminal UT4.

  Further, since no packet addressed to the wireless terminal UT4 arrives at the wireless terminal UT1, the information of the wireless terminal UT3 and the wireless terminal UT4 in the RA table of the wireless terminal UT1 is deleted after a sufficient time has elapsed.

(3.4) Operation example 4
19 and 20 are explanatory diagrams of operation example 4 of the communication system according to the present embodiment.

  As shown in FIG. 19, a wireless terminal UT3 having the wireless terminal UT4 as a child node is connected to the wireless terminal UT1.

  Information on the wireless terminal UT1, the wireless terminal UT2, the wireless terminal UT3, and the wireless terminal UT4 is registered in the IP address management device ARN and the wireless base station BS1.

  As shown in FIG. 20, it is assumed that the radio terminal UT3 moves and is directly connected to the radio base station BS1.

  The radio terminal UT3 transmits a connection request to the radio base station BS1, and the radio base station BS1 detects that an IP address has already been assigned to the radio terminal UT3. The radio base station BS1 changes the information of the radio terminal UT3 currently registered in the radio base station BS1 to RA “3” assigned by the radio base station BS1.

  As the RA of the radio terminal UT3 is changed to RA “3”, the radio base station BS1 rewrites the information of the radio terminal UT4 connected to the radio terminal UT3 to RA “3.3”.

  Further, the information on the wireless terminal UT3 and the wireless terminal UT4 in the wireless terminal UT1 is deleted after a sufficient time has elapsed since packets for these nodes do not arrive.

(3.5) Operation example 5
21 to 23 are explanatory diagrams of an operation example 5 of the communication system according to the present embodiment.

  As shown in FIG. 21, the radio terminal UT1, the radio terminal UT2, the radio terminal UT3, and the radio terminal UT4 are already registered on the IP address management device ARN and the radio base station BS1. RA “1”, RA “2”, RA “3”, and RA “3.3” are assigned to the wireless terminal UT1, the wireless terminal UT2, the wireless terminal UT3, and the wireless terminal UT4, respectively.

  As illustrated in FIG. 22, when the wireless terminal UT3 moves and connects to the wireless terminal UT1, the wireless terminal UT3 transmits a connection request to the wireless terminal UT1.

  The radio terminal UT1 assigns a new RA “1” to the radio terminal UT3 and simultaneously notifies the radio base station BS1 that the radio terminal UT3 is connected.

  Since the wireless base station BS1 has the IP addresses “172.16.0.3” and “172.16.0.4” assigned to the wireless terminal UT3 and the wireless terminal UT4 under the wireless terminal UT3, the wireless terminal UT3 Also, the registration information of the wireless terminal UT4 is rewritten to RA “1.1” and RA “1.1.3” which are subordinate to RA “1” notified from the wireless terminal UT1.

  As shown in FIG. 23, the wireless terminal UT4 transmits a packet to the IP address management device ARN, or a route search message or packet from the direction of the IP address management device ARN is transmitted to the wireless base station BS1, the wireless terminal UT1, the wireless terminal UT3. When arriving through the wireless terminal UT1, the wireless terminal UT1 recognizes that the wireless terminal UT4 is RA “1.1.3” under the wireless terminal UT3, and adds the RA to the RA table on the wireless terminal UT1.

(4) Operation and Effect As described above, the communication system according to the present embodiment is connected to the Internet 100, and the IP address management device ARN that manages the IP address, and the IP address is assigned by the IP address management device ARN. It comprises a plurality of radio base stations BS and a plurality of radio terminals UT that constitute a tree structure network with the IP address management device ARN as the highest level.

  The IP address management device ARN associates a base station address for identifying the radio base station BS with an IP address assigned to the radio terminal UT connected to the radio base station BS directly or via a relay node (radio terminal UT). The packet is relayed to the radio base station BS based on the base station address in the base station address table.

  The radio base station BS and the radio terminal UT associate the IP address assigned to the radio terminal UT connected to the own node directly or via the relay node with the RA used to relay the packet to the radio terminal UT. The packet is relayed to the wireless terminal UT based on the RA in the RA table.

  Thus, the packet relay destination can be specified based on the base station identifier or the node identifier, and the IP address management device ARN can change the wireless terminal UT related to the network configuration change even if the network configuration of the ad hoc network is changed. There is no need to reassign the IP address to the.

  Therefore, when the wireless terminal UT accesses the Internet 100 by communicating with a wireless base station via another wireless terminal UT, a period in which communication is interrupted in the wireless terminal UT related to the change in the network configuration of the ad hoc network is set. It can be shortened. For this reason, even when the wireless terminal UT communicates with the wireless base station BS through an ad hoc network, it is possible to execute a real-time application such as VoIP (Voice over Internet Protocol).

  Further, according to the present embodiment, the radio base station BS and the radio terminal UT relay a packet to a radio communication node that is directly connected to the own node based on the RA. As a result, the radio base station BS and the radio terminal UT can reliably relay the packet.

  According to the present embodiment, when an IP address is assigned by the IP address management device ARN, the wireless terminal UT transmits a connection request message including the assigned IP address (CalledIPAddress) to an upper communication node. In this embodiment, since the IP address is maintained even if the network configuration of the ad hoc network is changed, the upper communication node that has received the IP address can identify the wireless terminal UT that has transmitted the connection request message.

  According to the present embodiment, when the radio base station BS and the radio terminal UT directly receive a connection request message from the radio terminal UT, the radio base station BS and the radio terminal UT assign an RA to the radio terminal UT that has transmitted the connection request message. To the communication node. As described above, the assigned RA is used as relay information for routing packets. Therefore, the radio base station BS and the radio terminal UT can generate route information, and a load for generating route information can be distributed.

  According to the present embodiment, the radio base station BS and the radio terminal UT update the RA table in accordance with the SourceTreeAddress included in the connection request message. For this reason, it is possible to immediately update the route information after the network configuration of the ad hoc network is changed, and it is possible to further shorten the period during which communication is interrupted in the wireless terminal UT.

(5) Other Embodiments As described above, the present invention has been described according to the embodiment. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the above-described embodiment, the case where each wireless terminal UT accesses the Internet 100 has been described. However, the wireless terminal UT is not limited to the Internet, and may be another wired network.

  In the above-described embodiment, the portable wireless terminal is exemplified as the wireless terminal UT configuring the ad hoc network. However, an ad hoc network including a fixed wireless terminal may be configured.

  Thus, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the invention specifying matters in the scope of claims reasonable from this disclosure.

1 is an overall schematic configuration diagram of a communication system according to an embodiment of the present invention. It is a functional block diagram which shows the structure of the IP address management apparatus which concerns on embodiment of this invention. It is a functional block diagram which shows the structure of the wireless base station which concerns on embodiment of this invention. It is a functional block diagram which shows the structure of the radio | wireless terminal which concerns on embodiment of this invention. It is a figure which shows the structure of the connection request message and route search message which concern on embodiment of this invention. It is a flowchart which shows the operation | movement flow of the packet relay operation | movement performed by the IP address management apparatus which concerns on embodiment of this invention. It is a flowchart which shows the operation | movement flow of the connection request message reception operation | movement performed by the IP address management apparatus which concerns on embodiment of this invention. It is a flowchart which shows the operation | movement flow of the packet relay operation | movement performed by the wireless base station and wireless terminal which concern on embodiment of this invention. It is a flowchart which shows the operation | movement flow of the connection request message reception operation | movement performed by the wireless base station and wireless terminal which concern on embodiment of this invention. It is a flowchart which shows the operation | movement flow of the route search message reception operation | movement performed by the wireless base station which concerns on embodiment of this invention. It is a flowchart which shows the operation | movement flow of the route search message reception operation | movement performed by the radio | wireless terminal which concerns on embodiment of this invention. It is explanatory drawing of the operation example 1 of the communication system which concerns on embodiment of this invention (the 1). It is explanatory drawing of the operation example 1 of the communication system which concerns on embodiment of this invention (the 2). It is explanatory drawing of the operation example 2 of the communication system which concerns on embodiment of this invention (the 1). It is explanatory drawing of the operation example 2 of the communication system which concerns on embodiment of this invention (the 2). It is explanatory drawing of the operation example 3 of the communication system which concerns on embodiment of this invention (the 1). It is explanatory drawing of the operation example 3 of the communication system which concerns on embodiment of this invention (the 2). It is explanatory drawing of the operation example 3 of the communication system which concerns on embodiment of this invention (the 3). It is explanatory drawing of the operation example 4 of the communication system which concerns on embodiment of this invention (the 1). It is explanatory drawing of the operation example 4 of the communication system which concerns on embodiment of this invention (the 2). It is explanatory drawing of the operation example 5 of the communication system which concerns on embodiment of this invention (the 1). It is explanatory drawing of the operation example 5 of the communication system which concerns on embodiment of this invention (the 2). It is explanatory drawing of the operation example 5 of the communication system which concerns on embodiment of this invention (the 3).

Explanation of symbols

  ARN ... IP address management device, BS ... wireless base station, UT ... wireless terminal, 100 ... Internet, 201 ... wired communication I / F unit, 202 ... base station address table management unit, 203 ... packet relay unit, 204 ... message processing Unit 205, storage unit 301, wireless processing unit 302 control unit 303 RA table management unit 304 packet relay unit 305 message processing unit 306 storage unit 401 wireless processing unit 402 Control unit, 403 ... RA table management unit, 404 ... Packet relay unit, 405 ... Message processing unit, 406 ... Storage unit

Claims (8)

An address management device that is connected to a wired network and manages an address used to access the wired network;
An address is assigned by the address management device, and a communication system comprising a plurality of wireless communication nodes constituting a tree-structured network with the address management device as the highest level,
The wireless communication node is
A relay node that relays a packet including an address assigned by the address management device;
A base station node directly connected to the address management device,
The address management device includes:
Base station information table storage for storing a base station information table in which a base station identifier for identifying the base station node is associated with an address assigned to a radio communication node connected to the base station node directly or via a relay node And
A first packet relay unit that relays a packet to the base station node based on the base station identifier in the stored base station identifier table;
The wireless communication node is
Stores a route information table in which addresses assigned to lower wireless communication nodes connected directly to the own node or via relay nodes are associated with route information used for relaying packets to the lower wireless communication nodes. A route information table storage unit to
A second packet relay unit that relays a packet to the lower wireless communication node based on the route information in the stored route information table;
The communication system includes a node identifier of the lower-layer wireless communication node and a node identifier of a relay node on a communication route between the own node and the lower-layer wireless communication node. An address is assigned by an address management device that manages an address used to access a wired network, and is a wireless communication node in a plurality of wireless communication nodes constituting a tree-structured network with the address management device as the highest level,
Stores a route information table in which addresses assigned to lower wireless communication nodes connected directly to the own node or via relay nodes are associated with route information used for relaying packets to the lower wireless communication nodes. A route information table storage unit to
A packet relay unit that relays a packet to the lower-layer wireless communication node based on the route information in the stored route information table;
The path information includes a node identifier of the subordinate radio communication node and a node identifier of a relay node on a communication path between the own node and the subordinate radio communication node. The packet relay unit
A route information acquisition unit that acquires route information corresponding to an address included in the packet from the route information table;
Among node identifiers included in the route information acquired by the route information acquisition unit, a node identifier acquisition unit that acquires a node identifier of a wireless communication node that is directly connected to the own node;
The wireless communication node according to claim 2, further comprising: a packet transmission unit that transmits a packet to the wireless communication node indicated by the node identifier acquired by the node identifier acquisition unit. A connection request transmitting unit that transmits a first connection request for requesting connection to an upper wireless communication node to the upper wireless communication node;
3. The wireless communication according to claim 2, wherein, when an address is assigned by the address management device, the connection request transmission unit transmits the first connection request including the assigned address to the higher-order wireless communication node. node. A first connection request receiving unit that receives a second connection request for requesting direct connection to the own node from a lower-layer wireless communication node;
When the first connection request receiving unit receives the second connection request, an identifier assigning unit that assigns a node identifier to the wireless communication node that has transmitted the second connection request;
The wireless communication node according to claim 4, further comprising: a node identifier notifying unit that notifies the upper wireless communication node of the second connection request including the node identifier assigned by the identifier assigning unit. A second connection request receiving unit for receiving a third connection request including a node identifier from the relay node;
The route information table updating unit that updates the route information table according to a node identifier included in the third connection request when the second connection request receiving unit receives the third connection request. 5. A wireless communication node according to 5. An address management device that assigns addresses used for accessing a wired network to a plurality of wireless communication nodes and manages the assigned addresses,
A base station information table in which a base station identifier for identifying a base station node directly connected to the address management device and an address assigned to a wireless communication node connected to the base station node directly or via a relay node are associated with each other A base station information table storage unit for storing;
An address management device comprising: a packet relay unit that relays a packet to the base station node based on the base station identifier in the stored base station identifier table. An address management device that is connected to a wired network and manages an address used to access the wired network;
An address is assigned by the address management device, and comprises a plurality of wireless communication nodes constituting a tree-structured network with the address management device as the highest level,
The wireless communication node is
A relay node that relays a packet including an address assigned by the address management device;
A communication method used in a communication system including a base station node directly connected to the address management device,
The address management device stores a base station information table in which a base station identifier for identifying the base station node is associated with an address assigned to a radio communication node connected to the base station node directly or via a relay node And steps to
The wireless communication node associates an address assigned to a lower wireless communication node connected to the own node directly or via a relay node with path information used for relaying a packet to the lower wireless communication node. Storing a route information table,
The address management device relaying a packet to the base station node based on the base station identifier in the stored base station identifier table;
The wireless communication node relays a packet to the lower wireless communication node based on the route information in the stored route information table;
The communication method includes a node identifier of the lower radio communication node and a node identifier of a relay node on a communication path between the own node and the lower radio communication node.