JP4057715B2 - Router device, wireless terminal device, wireless base station, and message transmission control method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a router that is installed in a network that accommodates wireless terminals and can transfer data packets transferred from the wireless network to the destination of the wireless terminal that moves across those networks. The present invention relates to a wireless terminal capable of performing communication, a wireless base station communicating with the wireless terminal, and a message transmission control method.
[0002]
[Prior art]
The router device is used when connecting networks, and plays a role of transferring a datagram (data packet) from one network to the other network. In the datagram, in addition to the communication information data to be transferred, the network layer address of the transmission source and the final destination (for example, IP address in the case of IP) is described. In the router device, the data is based on the address information. Gram output interface (port number) and next transfer destination node (to be a router or a communication terminal) are determined.
[0003]
In the network, routing by the router device will be described taking an example in which an IP packet is transmitted from terminal A to terminal B. In this case, the IP packet transmitted from the terminal A is routed in the Internet by the IP address and transmitted to the subnet to which the terminal B belongs. At this time, each time an IP packet transmitted from the terminal A passes through a router device in the Internet, an IP forwarding process such as data link layer → IP packet → IP header information etc. processing / output destination determination → data link layer packet Is done. When this IP packet arrives at the router device of the final subnet, conversion from a logical address to a physical address is performed by ARP (Address Resolution Protocol) (a MAC address is acquired from the IP address), and data such as the MAC address is stored in the IP packet. The link layer header information is added, converted into a data link layer packet, and transmitted to the terminal B. When a part of the transfer path is a wireless transmission path and an IP packet is transferred on the wireless transmission path, information such as a wireless channel is specified in the MAC address of the link layer.
[0004]
On the other hand, a technique for accommodating a mobile terminal in an Internet network has been researched / developed. As such mobile access technology, a method using Mobile IP can be mentioned.
[0005]
When a user carrying a mobile terminal considers moving and communicating on an IP network, the network address of the mobile terminal changes with movement (change in position). For this purpose, Mobile IP is used. In other words, MobileIP is a technology that makes a mobile terminal appear to be at a place where the mobile terminal is originally connected (home address of the home network), regardless of where the mobile terminal is connected on the network. It was standardized as RFC2002 by IETF in October of the year.
[0006]
Even when the location on the network is changed while performing communication using a mobile terminal having a wireless interface, the switching process (handoff) of the wireless base station in communication with the wireless base station is not performed in the network layer. Mobile IP can be used without any special modification.
[0007]
The basic operation of Mobile IP will be described below with reference to FIG.
In a network (home network) 101-1 to which the mobile terminal (MH) 105 is originally connected, a router called a home agent (HA) 106 is installed. The address (home address) of the mobile terminal 105 is set to “10.2”, and the address of the home agent 106 is set to “10.1”.
[0008]
Here, it is assumed that the mobile terminal 105 has moved from the position of the home address “10.2” and connected to the destination network 101-2. A router (FA) 103 called a foreign agent is installed at the destination. The address of the foreign agent 103 is “20.1”. When the mobile terminal 105 moves, the mobile terminal 105 receives a packet addressed to itself through the foreign agent 103.
[0009]
The mobile terminal 105 notifies the home agent 106 of the IP address “20.1” of the current position in order to notify the current position of the own device (in this case, the address of the foreign agent 103, that is, “20.1”). Notice. Receiving this, the home agent 106 manages the correspondence between the home address “10.2” of the mobile terminal 105 and the current location address “20.1”.
[0010]
Now, the communication partner (CH) 107 trying to communicate with the mobile terminal 105 does not know that the mobile terminal 105 has moved, and transmits a packet to its home address “10.2”. However, since the mobile terminal 105 is not currently present at the home address position “10.2”, the home agent 106 managing it intercepts the packet addressed to this address “10.2” and registers it in advance. And encapsulated in an IP packet addressed to the current location address “20.1”. The foreign agent 103 at the address “20.1” takes out the packet in the transferred packet and delivers it to the moving mobile terminal 105 using the link layer address. Accordingly, the mobile terminal 105 can receive a packet that the device itself would have received on the home link.
[0011]
When returning a packet from the current position to the communication partner 107 in the reverse direction, the IP packet is directly output to the access source without going through the home agent 106. At this time, the source address is not the current position “20.1” but the home address “10.2”. As a result, the mobile terminal 105 appears to the communication partner 107 as if it is still connected to the home link, and the influence of movement is eliminated.
[0012]
With such a mechanism, each node on the network can access the mobile terminal using the home address of the mobile terminal, wherever the mobile terminal is connected.
[0013]
Thus, by using Mobile IP to route data packets addressed to mobile terminals, there are the following advantages.
(1) It is possible to move across multiple subnets.
[0014]
When supporting data packet communication between a mobile terminal, which is a wireless terminal, and a wireless base station, a certain coverage area (an area including the coverage area of a plurality of wireless base stations) is mapped to one IP subnet (ie, In many cases, the plurality of radio base stations are mapped to one IP subnet). In this case, when the wireless terminal moves from the coverage area of the wireless base station located at the outer edge portion of a certain area to an adjacent area (coverage area of the wireless base station located at the outer edge portion) different from that area, Movement across IP subnets is performed (see FIG. 1). When such a movement across the IP subnet occurs, the destination subnet cannot continue to use the IP address used until then, but the Mobile IP that automatically forwards the packet to the destination subnet By using this routing, even when moving to an area belonging to another subnet, it becomes possible to continue communication using the address as it is.
[0015]
(2) When moving, a TCP / IP session can be held.
In particular, by using Mobile IP, even when moving across subnets as described above in a state where the communication program has already been started, the movement process is performed while retaining the previous TCP / IP session. It becomes possible to do. For example, it is possible to move to another subnet while continuing the FTP file transfer program.
[0016]
In addition, when moving across subnets using Mobile IP, it is necessary to recognize the occurrence of this movement in the mobile terminal device itself. However, in the Mobile IP system, RFC 2002 is used as a system for detecting movement across subnets. For example, the following are shown.
[0017]
(A) Looking at the transmission source of a packet such as ARP flowing through the destination network, the network address portion is examined, and it is estimated that the packet has moved to another network.
[0018]
(B) If it is certain that the foreign agent exists in the destination network, the foreign agent receives an agent advertisement message periodically broadcast (broadcast) to the subnet, and sets the network address of the source address of the agent advertisement message. Investigate and decide to move to another network.
[0019]
(C) If it is certain that the foreign agent exists in the destination network, the mobile node transmits an agent solicitation message (Agent Solicitation) for searching for the foreign agent, and checks the network address of the foreign agent address responding thereto. Detects that it has moved to another network.
The wireless terminal transmits and receives an agent advertisement message, an agent request message, and a response message through the wireless base station.
[0020]
[Problems to be solved by the invention]
In general, in a system that accommodates wireless terminals, transfer (handoff) of wireless terminals between wireless base stations can be performed at extremely high speed using a link layer mechanism.
[0021]
However, when data communication is performed from the wireless terminal through the IP network and the movement of the wireless terminal across the IP subnet is performed using Mobile IP technology, the foreign agent is periodically issued as described above. In the method in which the wireless terminal checks the current movement destination of its own device based on the agent advertisement message or agent request message, it takes time to detect movement compared to the handoff between wireless base stations by the link layer mechanism, and smooth inter-IP subnet communication There was a problem that it could not be moved.
[0022]
The present invention has been made in consideration of the above circumstances, and is currently installed on a network when packet communication is performed from a wireless terminal through an IP network or the like, and the wireless terminals currently traveling between each other in cooperation with each other A router that manages location information, routes a communication packet from a communication partner to the current location of the wireless terminal, and enables high-speed detection of movement of the wireless terminal across a subnetwork such as an IP subnet It is an object to provide a device, a wireless portable terminal device, a wireless base station, and a message transmission control method.
[0023]
[Means for Solving the Problems]
Main departure Tomorrow A router device (for example, a foreign agent) installed in a network that can accommodate wireless terminals that can move between networks and communicate with each other by a wireless base station. Means for broadcasting a predetermined message including identification information (for example, foreign agent advertisement message) at predetermined time intervals, the original network layer address of the wireless terminal that has moved into the subnet to which the device belongs, and the current Means for managing the correspondence with the link layer address of the location, and if the packet forwarded to its own device is in an encapsulated form, unencapsulate and check the destination address of the obtained packet , The link layer address of the current position corresponding to the destination address as the original network layer address Means for delivering the packet obtained by examining and decapsulating the packet to the link layer address corresponding to the current position, and a predetermined notification notified from a radio base station installed in the subnet to which the device belongs Based on control information (for example, terminal mobility message), the time interval for broadcasting the predetermined message is controlled to be a time interval shorter than the predetermined time interval for a certain period of time. And a means for doing so.
[0024]
Preferably, the predetermined control information notified from the radio base station is such that at least one radio terminal is connected to another radio base station geographically adjacent to the radio base station and belonging to a different subnet. May be used.
[0025]
Main departure Tomorrow A router device (for example, a foreign agent) installed in a network that can accommodate wireless terminals that can move between networks and communicate with each other by a wireless base station. Means for broadcasting a predetermined message including identification information (for example, foreign agent advertisement message) at predetermined time intervals, the original network layer address of the wireless terminal that has moved into the subnet to which the device belongs, and the current Means for managing the correspondence with the link layer address of the location, and if the packet forwarded to its own device is in an encapsulated form, unencapsulate and check the destination address of the obtained packet , The link layer address of the current position corresponding to the destination address as the original network layer address Means for delivering the packet obtained by examining and decapsulating the packet to the link layer address of the corresponding current position, and the radio terminal from the radio base station installed in the subnet to which the own device belongs to the own station Receives information indicating that at least one is connected and information on a group of radio base stations adjacent to the radio base station, and searches for a router device managing each radio base station included in the radio base station group When at least one of the searched router devices is different from the own device, the time interval for broadcast transmission of the predetermined message is shortened for a fixed time to a router device different from the own device. Based on the predetermined control information notified from a router device installed in another subnet, and means for notifying predetermined control information (for example, a terminal mobility message) indicating that it should be , The time interval for broadcast transmission of the predetermined message, only during a certain time, characterized by comprising a means for controlling so as to a time interval shorter than the predetermined time interval.
[0026]
Preferably, the identification information is used for detecting that the wireless terminal that has moved into the subnet to which the device belongs has moved to a different subnet from the subnet to which the terminal has belonged. Also good.
[0027]
Preferably, the control information is inspected at a constant time interval, and if the predetermined control information satisfies a predetermined condition, the time interval of broadcast transmission of the predetermined message is shortened by a predetermined time, When the predetermined control information does not satisfy the predetermined condition, the broadcast transmission time interval may be left at the original predetermined time interval.
[0028]
Main departure Tomorrow A wireless base station that communicates with a wireless terminal that is accommodated in a router device (for example, a foreign agent) and can communicate by moving between networks. Means for holding the subnet address to which the foreign agent) belongs, means for detecting that at least one wireless terminal is connected to the local station, and indicating the subnet address to other geographically adjacent wireless base stations Means for notifying information including information and that at least one wireless terminal is connected to the local station, and the subnet address included in the information and the subnet held by the local station when the information is notified If the address is compared, and the two do not match, a predetermined message containing the identification information (example) For example, there is provided means for notifying predetermined control information (for example, a terminal mobility message) indicating that the time interval for broadcasting the foreign agent advertisement message) should be shortened for a certain period of time. It is characterized by.
[0029]
Main departure Tomorrow A wireless base station that is accommodated in a router device (for example, a foreign agent) and communicates with a wireless terminal that can move and communicate between networks, and is a wireless base station adjacent to the wireless terminal station, Means for holding list information of the subnet address of the router device accommodated different from that of the own station, means for detecting that at least one wireless terminal is connected to the own station, and at least one of the own station Means for notifying the wireless base station included in the list information of information including that at least one wireless terminal is connected to the wireless base station when the wireless terminal is detected to be connected; When the information is notified, broadcast transmission of a predetermined message (for example, a foreign agent advertisement message) including the identification information to the router device in which the device is accommodated. Predetermined control information indicating that it should be as short as between between interval predetermined time (e.g., terminal movability message), characterized in that a means for notifying.
[0030]
Main departure Tomorrow A wireless base station that is accommodated in a router device (for example, a foreign agent) and communicates with a wireless terminal that can move between networks and perform communication, and the wireless base station group in which the local station forms a subnet. Means for recognizing whether or not it belongs to a geographical outer edge, means for detecting that at least one wireless terminal is connected to the own station, and a group of wireless base stations in which the own station forms a subnet And when it is detected that at least one wireless terminal is connected to the local station, the local terminal is connected to the wireless terminal connected to the local station. A predetermined message (for example, a foreign agent request message) for obtaining the identification information of the router device accommodating the connected radio base station should be transmitted at a short time interval for a certain period of time. Characterized by comprising a means for notifying the movability message indicating effect.
[0031]
Main departure Tomorrow A wireless terminal that is connected to a router device via a wireless base station and can communicate by moving between networks, and is installed in a subnet that covers the geographical current position of the terminal. Means for transmitting a predetermined message (for example, foreign agent request message) information for inquiring a router device (for example, a foreign agent) for supporting a wireless terminal, and a wireless base station to which the own device is connected And a means for controlling the predetermined message to be transmitted at a short time interval for a predetermined time based on position information including information on the notified geographical position.
[0032]
Preferably, the means for detecting that the terminal has moved from the network to which the terminal belongs to a different network based on the information of the source address included in the response message returned from the router device that has received the predetermined message. May be further provided.
[0033]
Preferably, the location information notified from the radio base station indicates that at least one of the other radio base stations adjacent to the radio base station belongs to a network different from the current network. It may be.
[0034]
Preferably, the location information notified from the radio base station is checked at regular time intervals, and the location information indicates that at least one of the other radio base stations adjacent to the radio base station is connected to the current network. Indicates that it belongs to a different network, the time interval of transmission of the predetermined message is shortened by a fixed time, and the position information is another radio base station adjacent to the radio base station. If at least one of them does not indicate that it belongs to a network different from the current network, the predetermined message transmission time interval may remain unchanged.
[0035]
Main departure Tomorrow , A plurality of wireless base stations that communicate with wireless terminals that can move between subnets, and a plurality of subnets that have router devices (for example, foreign agents) that transfer data packets transferred through the wireless base stations. A method for controlling message transmission of a router device in an interconnected network, wherein a predetermined message (for example, a foreign agent advertisement message) including identification information of the own device in a subnet to which the own device belongs is synchronized at a predetermined time interval. The predetermined message is transmitted only for a certain period of time based on predetermined control information (for example, terminal mobility message) notified from a radio base station installed in the subnet to which the device belongs. The broadcast transmission is performed at a time interval shorter than the predetermined time interval.
[0036]
Preferably, the predetermined control information notified from the radio base station is such that at least one radio terminal is connected to another radio base station geographically adjacent to the radio base station and belonging to a different subnet. May be used.
[0037]
Main departure Tomorrow , A plurality of wireless base stations that communicate with wireless terminals that can move between subnets, and a plurality of subnets that have router devices (for example, foreign agents) that transfer data packets transferred through the wireless base stations. A method for controlling message transmission of a router device in an interconnected network, wherein a predetermined message (for example, a foreign agent advertisement message) including identification information of the own device in a subnet to which the own device belongs is synchronized at a predetermined time interval. Information indicating that at least one wireless terminal is connected to the local station from the wireless base station installed in the subnet to which the local apparatus belongs, and information on a group of wireless base stations adjacent to the wireless base station, When a router device that manages each wireless base station included in the wireless base station group is searched, When at least one of the data devices is different from its own device, the time interval for broadcast transmission of the predetermined message should be shortened for a fixed time to a router device different from the own device When the predetermined control information (for example, terminal mobility possibility message) is notified and the predetermined control information is received from a router device installed in another subnet, the predetermined message is transmitted for a certain period of time. During the period, broadcast transmission is performed at a time interval shorter than the predetermined time interval.
[0038]
Preferably, data exchange for movement of the wireless terminal between the wireless base stations is performed using a channel switching mechanism on a wireless link, and data processing for movement between the wireless base stations accompanied by the change of the subnet is registered in Mobile IP Alternatively, it may be performed by data transfer.
[0039]
Preferably, the identification information is used for detecting that the wireless terminal that has moved into the subnet to which the device belongs has moved to a different subnet from the subnet to which the terminal has belonged. Also good.
[0040]
Preferably, the control information is inspected at a constant time interval, and if the predetermined control information satisfies a predetermined condition, the time interval of broadcast transmission of the predetermined message is shortened by a predetermined time, When the predetermined control information does not satisfy the predetermined condition, the broadcast transmission time interval may be left at the original predetermined time interval.
[0041]
Preferably, the wireless terminal may be a portable wireless terminal.
The present invention relating to the apparatus is also established as an invention relating to a method, and the present invention relating to a method is also established as an invention relating to an apparatus.
[0042]
Further, the present invention relating to an apparatus or a method has a function for causing a computer to execute a procedure corresponding to the invention (or for causing a computer to function as a means corresponding to the invention, or for a computer to have a function corresponding to the invention It can also be realized as a computer-readable recording medium on which a program (for realizing) is recorded.
[0043]
According to the present invention, a wireless base station that covers the outer edge of the coverage area of a certain subnet (a wireless base station having an adjacent wireless base station that belongs to a subnet different from the own station; a router device such as a foreign agent different from the own station) If at least one wireless terminal is connected to a wireless base station having an adjacent wireless base station that is connected to the wireless base station), the wireless base station sends a message to that effect to the router device of a different subnet that can be the destination of the wireless terminal. The router that has received this notification resets the broadcast interval of the agent advertisement message, etc. for a certain period of time shorter than usual, and then the wireless terminal actually uses its own device. To reduce the time required for movement detection in the wireless terminal when moving into the coverage area, ie subnet It can be.
[0044]
In addition, by appropriately adjusting the time range for shortening the broadcast interval, the number of unnecessary packets can be increased in consideration of the coverage area of each wireless base station, the moving speed of wireless mobile terminals, the amount of traffic allowed on the network, etc. In this case, the movement detection based on Mobile IP can be performed at high speed.
[0045]
According to the present invention, a wireless base station that covers the outer edge of the coverage area of a certain subnet (a wireless base station having an adjacent wireless base station that belongs to a subnet different from the own station; a router device such as a foreign agent different from the own station) When at least one wireless terminal is connected to a wireless base station having an adjacent wireless base station that is connected to the wireless base station), the wireless base station is notified to that effect. The wireless terminal can shorten the time required for movement detection when the wireless mobile terminal roams to a wireless base station that actually belongs to a different subnet by shortening the transmission interval of the agent request message or the like. .
[0046]
In addition, by appropriately adjusting the time range for shortening the transmission interval of the agent request message, the number of unnecessary packets may be increased in consideration of the coverage area of each radio base station, the amount of traffic allowed in the network, etc. In addition, movement detection based on Mobile IP can be performed at high speed.
[0047]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the invention will be described with reference to the drawings.
FIG. 1 shows a basic configuration example of a network according to an embodiment of the present invention.
In this network, a plurality of router devices having a function of transferring data packets transferred via each wireless base station 4 to an IP network (for example, the Internet) 1 are installed, and a plurality of router devices are provided via the plurality of router devices 3. It is assumed that the networks 2-1 and 2-2 are connected to each other. The network in the form illustrated in FIG. 1 is operated by, for example, a wireless communication carrier.
[0048]
In addition, terminals and routers having other IP addresses may be connected to each IP subnet.
One router device 3 is mapped to a network corresponding to one subnet. That is, while the wireless portable terminal 5 is moving in a geographical area covered by a predetermined number of wireless base stations 4, the wireless portable terminal 5 belongs to the same subnet and its IP address is also constant. It is assumed that this does not change. The subnet range can be set as appropriate, but if too many terminals are accommodated, the traffic volume of ARP packets transmitted from each terminal to the subnet will increase, resulting in performance degradation. It is desirable to divide into two.
[0049]
When the wireless portable terminal 5 moves, if it moves between the wireless base stations 4 accommodated in the same router device 3, the IP address assigned in the IP network does not change, and therefore the link layer (wireless link) The hand-off process of the wireless portable terminal is performed by the channel change function in FIG. The handoff by this link layer function can be performed at extremely high speed.
[0050]
On the other hand, when the wireless portable terminal 5 moves between the wireless base stations 4 accommodated in different router devices 3 (that is, between the wireless base stations 4 in different sub-networks), it is necessary to change the IP address. . For this purpose, Mobile IP defined by IETF RFC2002 is used, the packet is encapsulated and transferred to a newly acquired address (Care-of address) in the destination network, and the data that has been decapsulated is transferred. A method of supplying to a wireless portable terminal is used.
[0051]
For this purpose, it is assumed that the router apparatus 3 arranged in each network operates as a foreign agent defined by RFC2002. That is,
When the mobile wireless terminal 5 moves to Mobile IP, the Care-of Address is the foreign agent, that is, the IP address of the node device 3.
-A packet addressed to a moving wireless portable terminal is encapsulated in an IP packet addressed to a foreign agent, transferred, decapsulated by a foreign agent 3, and delivered to the corresponding wireless portable terminal 5 by a link layer mechanism. The
In order to perform this delivery, a correspondence table between the link layer address and the IP (home) address is created when relaying the registration message of the wireless portable terminal 5.
[0052]
As a method for detecting movement across subnets in the Mobile IP method, RFC 2002 shows the following method.
(A) Looking at the transmission source of a packet such as ARP flowing through the destination network, the network address portion is examined, and it is estimated that the packet has moved to another network.
(B) If it is certain that the foreign agent exists in the destination network, the foreign agent periodically receives an agent advertisement message broadcast to the subnet, and examines the network address of the source address to check another network. Determine that you have moved to.
(C) If it is certain that the foreign agent exists in the destination network, the mobile node transmits an agent solicitation message (Agent Solicitation) for searching for the foreign agent, and checks the network address of the foreign agent address responding thereto. Detects that it has moved to another network.
[0053]
Here, it is assumed that there is a foreign agent in each destination subnet, and the above method (b) or (c) is used.
Therefore, when the wireless portable terminal 5 moves to a different subnet, it is necessary to perform the following processing.
[0054]
(1) When the wireless portable terminal 5 listens to an agent advertisement message periodically broadcast by the foreign agent 3 of the destination subnet and recognizes that this is different from the subnet to which the device itself belongs, The foreign agent address is assumed to be a new Care-of address.
Instead of or together with this, the wireless portable terminal 5 transmits an agent solicitation message (Agent Solicitation) for searching for the foreign agent 3, and the network address of the foreign agent address in response thereto belongs to the own device until then. When recognizing that it is different from the one in the subnet, the foreign agent address of the sender is set as a new Care-of address.
[0055]
(2) When the wireless portable terminal 5 detects movement between subnets, it transmits an RFC2002 registration message to the home agent in the subnet before movement using Care-of address and receives a registration response message from the home agent. To do. Here, it is assumed that the router device (foreign agent) 3 in the subnet to which the wireless portable terminal 5 belonged before moving also operates as the home agent of RFC2002.
[0056]
(3) When registration is accepted by the home agent 3 in the pre-movement subnet, the home agent 3 thereafter transmits the packet transmitted to the original address to the foreign agent in the current subnet in the IP-in-IP system. (Refer to RFC2003) and Minimal Encapsulation (RFC2004), etc., and transfer using tunneling.
[0057]
(4) The foreign agent 3 in the destination subnet decapsulates and delivers the packet to the wireless portable terminal 5.
Note that the wireless portable terminal transmits and receives an agent advertisement message, an agent request message, and a response message via the wireless base station.
[0058]
Here, when solving the movement across the subnet, the processing that causes the most time loss is the operation of listening to the agent advertisement message (1) or the operation of transmitting the agent request message and listening to the response thereto. .
[0059]
In general, traffic on the subnet cannot be increased unnecessarily, so agent advertisement messages can only be broadcast on the order of hundreds of milliseconds to seconds. As for the agent solicitation message, when moving seamlessly to another network like a wireless terminal, it is not clear at what timing the agent solicitation message should be issued. Frequent transmission is not preferable because it wastes CPU power and network capacity of the terminal.
[0060]
Therefore, at each radio base station side,
(1) At least one wireless terminal is connected to a wireless base station adjacent to the own device, and
(2) The adjacent wireless base station belongs to a different network from the own device,
Detect the signal indicating
The foreign agent notified that these are turned on determines that a new wireless terminal will move to its own network in the near future and listen to the agent advertisement message. It is conceivable to perform a process of shortening.
[0061]
For example, when the coverage of each radio base station is as shown in FIG. 2, the detection of the above condition (1) is performed for the radio base stations 1, 2,. Just do it. Detection of the condition (1) is performed for the radio base stations 1, 2,..., N, and information that at least one of the radio base stations is connected to a radio base station belonging to an adjacent different network. When notified, the sending interval of the foreign agent agent advertisement message is shortened.
[0062]
Hereinafter, some configuration examples for realizing such control will be described.
<First configuration example>
First, a first configuration example will be described.
[0063]
In this example, the wireless portable terminal 5 performs at least inter-subnet movement detection based on the agent advertisement message.
FIG. 3 shows a configuration example of a foreign agent and a radio base station managed by the foreign agent.
[0064]
As shown in FIG. 3, the radio base station 4 (4-1 and 4-2 in FIG. 3) includes a subnet address register 41, a terminal connection status register 42, a communication unit 43 between adjacent radio base stations, a comparator. 44. Further, the foreign agent 3 has an agent advertisement transmission unit 31.
[0065]
The subnet address register 41 of each radio base station is a register that stores the IP subnet address in which the radio base station is accommodated, and is set when the IP network is configured. The terminal connection status register 42 is a register indicating that at least one wireless portable terminal is connected to the wireless base station.
[0066]
The radio base station (see 4-2) periodically updates the values of the subnet address register 41 and the terminal connection status register 42 via the communication unit 43 between the adjacent radio base stations and other radios whose coverage is adjacent. Notify the base station (see 4-1). Note that a control line or the like may be used for this notification.
[0067]
In the radio base station (see 4-1) on the side receiving this notification information, the notified value of the terminal connection status register 42 indicates ON, the notified value of the subnet address register 41, and the subnet of its own device. The comparator 44 checks that the address register 41 is different, and if both are detected, the foreign agent 3 is notified of a terminal mobility possibility message.
[0068]
The foreign agent 3 normally sends out an agent advertisement message at a predetermined time interval (broadcast transmission). Upon receiving this terminal mobility message, the foreign agent 3 sends a control command to the agent advertisement transmission unit 31 for a certain period of time. During this period, the agent advertisement message transmission interval is set shorter than the predetermined time interval.
[0069]
For example, when a wireless portable terminal uses a wireless channel of a wireless base station m belonging to a different network connected to the wireless base station 1 in FIG. 2, a terminal mobility message is notified as described above. The received foreign agent (router device) shortens the transmission interval of the agent advertisement message to, for example, 1/30 so far, and the wireless portable terminal is set in the subnet area of the own device during this fixed time. When it comes in, move detection can be performed at high speed.
[0070]
<Second configuration example>
Next, a second configuration example will be described.
In this example, each wireless base station manages the subnet information of adjacent wireless base stations, thereby making it possible to suppress the transmission of extra messages.
[0071]
Also in this example, the wireless portable terminal 5 performs at least inter-subnet movement detection based on the agent advertisement message.
FIG. 4 shows a configuration example of a foreign agent and a radio base station managed by the foreign agent.
[0072]
As shown in FIG. 4, the radio base station 4 (4-1 and 4-2 in FIG. 4) includes an adjacent radio base station information table 51, a terminal connection status register 52, and a communication unit 53 between adjacent radio base stations. Have Further, the foreign agent 3 has an agent advertisement transmission unit 31.
[0073]
Each radio base station maintains an adjacent radio base station information table 51 for managing adjacent radio base stations, and the subnet address to which each adjacent radio base station belongs and whether or not it matches the subnet of its own device. And flag information indicating that. Further, the terminal connection status register 52 is similar to FIG. 3 and is a register indicating that at least one wireless portable terminal is connected to the wireless base station.
[0074]
In this example, the radio base station (see 4-2) is configured so that the neighboring radio base station (4) whose flag information in the neighboring radio base station information table 51 is on only when the terminal connection status register 52 is turned on. -1), a message notification is performed. Note that a control line or the like may be used for this notification.
[0075]
Upon receiving this message from the adjacent radio base station, the radio base station (see 4-1) notifies the foreign agent 3 that accommodates the message of the terminal mobility possibility message.
[0076]
The foreign agent 3 that has received this terminal mobility possibility message sends a control command to the agent advertisement transmission unit 31 and shortens the agent advertisement message transmission interval for a certain period of time.
[0077]
<Third configuration example>
Next, a third configuration example will be described.
In this example, each wireless base station manages a list of neighboring wireless base stations, and the foreign agent side manages the correspondence table of foreign agents in the subnet to which each wireless base station belongs, thereby sending messages to the foreign agent. It is possible to suppress only in between.
[0078]
Also in this example, the wireless portable terminal 5 performs at least inter-subnet movement detection based on the agent advertisement message.
FIG. 5 shows a configuration example of a foreign agent and a radio base station managed by the foreign agent.
[0079]
As shown in FIG. 5, the radio base station 4 includes an adjacent radio base station information table 61, a terminal connection status register 62, and a communication unit 65. Further, the foreign agent 3 (3-1, 3-2 in FIG. 5) has registered the correspondence between the agent advertisement transmission unit 31, the identification information of the radio base station, and the foreign agent address to which the radio base station belongs. An FA address correspondence table 32 is provided.
[0080]
Each radio base station 4 has an adjacent radio base station information table that manages information on adjacent radio base stations. 61 Hold. Terminal connection status register 62 Is a register indicating that at least one wireless portable terminal is connected to the wireless base station, as in FIG.
[0081]
The foreign agent 3 has means for searching the correspondence relationship of the foreign agent addresses of the subnet to which each radio base station belongs. Here, the correspondence table 32 between the radio base station and the foreign agent is provided. However, the correspondence relationship may be inquired to an external server.
[0082]
In this example, the radio base station 4 has a terminal connection status register 62 Neighboring radio base station information table when is turned on 61 To the foreign agent (referred to as 3-1) that manages the radio base station. Note that a control line or the like may be used for this notification.
[0083]
The foreign agent (referred to as 3-1) uses the BS # -FA address correspondence table 32, for example, to transmit the adjacent radio base station information table. 61 Check whether there is something belonging to other than the subnet of the local device. If there is such a radio base station, the terminal mobility possibility message is notified to the corresponding foreign agent (referred to as 3-2). Note that a control line or the like may be used for this notification.
[0084]
Upon receiving this message, the foreign agent (referred to as 3-2) sends a control command to the agent advertisement transmission unit 31 to shorten the agent advertisement message transmission interval for a fixed time.
[0085]
By the way, in the agent advertisement message transmission interval control in each example as described above, if the agent advertisement message transmission interval is kept short, the traffic amount in the subnet becomes very large, which causes deterioration of network performance. Therefore, the time interval for broadcasting the agent advertisement message is shortened by a certain time range. For example, at first, the transmission interval is shortened only for 20 seconds, and the connection state of the wireless portable terminal to the wireless base station is checked again, and it seems that it is still connected to the outer edge wireless base station belonging to a different adjacent network. For example, the sending interval is shortened again for 20 seconds. Furthermore, if the wireless mobile terminal does not seem to move at all (for example, it does not move even after 2 minutes from the same wireless base station range), stop sending the agent advertisement message to the original transmission interval. Control such as returning to the interval is also possible.
[0086]
<Fourth configuration example>
Next, a fourth configuration example will be described.
In this example, when the wireless mobile terminal 5 detects that the mobile device is moving to a wireless base station in an area where it is likely to move across subnets, the agent request message is frequently transmitted, It is designed to detect movement across the network.
[0087]
In this example, the wireless portable terminal 5 performs at least inter-subnet movement detection based on the agent request message.
FIG. 6 shows a configuration example of a wireless portable terminal and a wireless base station.
[0088]
As shown in FIG. 6, the radio base station 4 includes subnet outer edge position information 71, a terminal connection status register 72, and a terminal communication unit 76. The wireless portable terminal 5 includes a Mobile IP processing unit 15.
[0089]
Each wireless base station 4 knows whether or not its own device is in the outer edge portion of the subnet cover range (position corresponding to the wireless base stations 1 to n in FIG. 2), and the wireless device in which the own device is located in the outer edge portion. If it is a base station, a signal indicating that it is connected to the wireless base station at such a position is sent to the connected wireless portable terminal 5. Upon receiving this signal, the wireless portable terminal 5 transmits an agent request message at a short time interval for a fixed time so that it can be immediately detected when moving across subnets.
[0090]
That is, in this example, each radio base station 4 holds subnet outer edge partial position information 71 indicating that it has a subnet different from at least one radio base station among neighboring radio base stations of its own device. To do. This is statically set by the network administrator when constructing the IP network and the wireless network.
[0091]
The wireless base station 4 whose subnet outer edge portion location information 71 is on transmits a subnet outer edge approach message to the wireless mobile terminal 5 that has moved and established a connection based on a unique protocol.
[0092]
Receiving this, the wireless portable terminal 5 sends a control signal to the Mobile IP processing unit 15, and after completing the IP connection, sends a Mobile IP agent request message at a relatively short interval for a certain period of time, and checks the response. The position information on the IP network is detected.
[0093]
In this case as well, the example in which the agent request message is continuously issued for a long time increases the traffic volume in the subnet, so that the location information is checked again after a certain time interval. It is desirable to control message transmission according to the same policy.
[0094]
As described above, the mobile IP handoff for the movement of the wireless portable terminal across the subnet can be reduced by shortening the transmission interval of the message necessary for the mobile IP movement detection on either the router side or the wireless portable terminal side. Smooth movement processing can be performed with minimum overhead.
[0095]
Conventionally, when a data packet transfer service to an IP network is performed using a wireless portable terminal, the terminal delivery (handoff) between each wireless base station can be performed at a very high speed using a link layer mechanism. On the other hand, when handoff of movement across multiple IP subnets is performed, an agent advertisement message broadcast to the subnet at a predetermined interval from the router device defined by Mobile IP method is received, and this source address is checked. In the method of deciding that the user has moved to another network or using the agent solicitation message to determine that the user has moved to another network, it takes time to detect the movement, and smooth inter-IP subnet movement is not possible. There was a problem.
[0096]
According to the present embodiment, for example, for each radio base station, information indicating whether or not a wireless mobile terminal is connected to the neighboring radio base station of the own device, each neighboring radio base station and the own device are accommodated When information indicating whether or not the wireless mobile terminal has moved to a different wireless base station in a neighboring IP network is detected and information indicating whether or not the IP network address is different is detected, the fact that the wireless base station is accommodated is detected. The router device that operates as a foreign agent of the IP subnet that receives the notification performs control such as resetting the broadcast interval of the agent advertisement message to be shorter than usual for a certain time. Then, if the wireless mobile terminal has moved into the foreign agent's coverage, that is, the subnet, It can be controlled so that it can reduce the time required for the movement detection of the terminal band terminal.
[0097]
In addition, by appropriately adjusting the time range for shortening the broadcast interval, the number of unnecessary packets can be increased in consideration of the coverage area of each wireless base station, the moving speed of wireless mobile terminals, the amount of traffic allowed on the network, etc. In this case, the movement detection based on Mobile IP can be performed at high speed.
[0098]
Further, according to the present embodiment, the location information on the subnet of the wireless base station to which each wireless mobile terminal is connected is checked, and when the wireless base station located at the outer edge of the subnet is connected, the agent request message is transmitted for a certain period of time. By shortening the interval, it is possible to control so that the time required for movement detection can be reduced when the wireless portable terminal subsequently roams to a wireless base station belonging to another subnet.
[0099]
In addition, by appropriately adjusting the time range for shortening the transmission interval of the agent request message, the number of unnecessary packets may be increased in consideration of the coverage area of each radio base station, the amount of traffic allowed in the network, etc. In addition, movement detection based on Mobile IP can be performed at high speed.
[0100]
In the above description, the mobile terminal in Mobile IP has been described as a wireless portable terminal, but it is of course possible to use a terminal having a wireless communication function that is not portable. Further, the wireless portable terminal or the wireless terminal need only be able to connect and use the wireless communication apparatus even if the communication function is not built in.
[0101]
The above functions can also be realized as software.
Further, the present embodiment is a computer readable recording program for causing a computer to execute predetermined means (or for causing a computer to function as predetermined means or for causing a computer to realize predetermined functions). It can also be implemented as a recording medium.
The present invention is not limited to the embodiment described above, and can be implemented with various modifications within the technical scope thereof.
[0102]
【The invention's effect】
According to the present invention, when at least one wireless terminal is connected to a wireless base station that covers the outer edge of the coverage area of a certain subnet, the router of a different subnet that can be the destination of the wireless terminal from the wireless base station The router device that has received this notification resets the broadcast interval for agent advertisement messages, etc. to a shorter time than usual for a certain time, and then the wireless terminal It is possible to reduce the time required for movement detection in the wireless terminal when the mobile terminal actually moves within the coverage area of the own apparatus, that is, the subnet.
[0103]
Also, according to the present invention, when at least one wireless terminal is connected to a wireless base station that covers the outer edge of the coverage area of a certain subnet, the wireless base station is notified of that fact. Therefore, the wireless terminal that has received this notification shortens the transmission interval of the agent request message and the like, and then, when the wireless mobile terminal roams to a wireless base station that actually belongs to a different subnet, it takes movement detection. Time can be shortened.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a basic configuration example of a network according to an embodiment of the present invention.
FIG. 2 is a diagram for explaining a coverage of the radio base station according to the embodiment;
FIG. 3 is a diagram showing a basic configuration example of a radio base station and a router device according to the embodiment;
FIG. 4 is a view showing another basic configuration example of the radio base station and the router device according to the embodiment;
FIG. 5 is a diagram showing still another basic configuration example of the radio base station and the router device according to the embodiment;
FIG. 6 is a diagram showing a basic configuration example of a radio base station and a radio mobile terminal according to the embodiment;
FIG. 7 is a diagram for explaining the basic operation of Mobile IP
[Explanation of symbols]
1 ... Internet
2-1, 2-2 ... Subnetwork
3,3-1, 3-2 ... router device
4,4-1,4-2 ... Wireless base station
5 ... Wireless portable terminal
15 ... Mobile IP processing unit
31 ... Agent advertisement transmission unit
41 ... Subnet address register
42, 52, 62, 72 ... terminal connection status register
43 ... Communication unit between adjacent radio base stations
44 ... Comparator
51 ... Adjacent radio base station information table
53. Communication unit between adjacent radio base stations
61 ... Adjacent radio base station information table
65. Communication unit
32 ... BS # -FA address correspondence table
71: Subnet outer edge position information
76. Terminal communication unit

Claims (11)

A router device installed in each subnet for managing a wireless base station to which a wireless terminal capable of communicating by moving between a plurality of subnets forming a network is connected ,
Transmitting means for broadcasting an advertisement message including identification information of the own device in a subnet to which the own device belongs at a first time interval or a second time interval shorter than the first time interval;
Means for creating a correspondence table between the original network layer address and link layer address of the wireless terminal that has moved into the subnet ;
When the packet transferred to the own device is in an encapsulated format, the link layer address corresponding to the original network layer address of the packet obtained by decapsulation is checked with reference to the correspondence table , Means for delivering the packet resulting from the decapsulation using the link layer address;
Indicating that it is notified from a radio base station installed in the subnet, at least one wireless terminal to another wireless base station belonging to the adjacent and the subnet different from the subnet to the wireless base station is connected A router for changing a time interval of broadcast transmission by the transmission means from the first time interval to the second time interval for a predetermined time based on control information; apparatus. A router device installed in each subnet for managing a wireless base station to which a wireless terminal capable of communicating by moving between a plurality of subnets forming a network is connected ,
Transmitting means for broadcasting an advertisement message including identification information of the own device in a subnet to which the own device belongs at a first time interval or a second time interval shorter than the first time interval;
Means for creating a correspondence table between the original network layer address of the wireless terminal that has moved into the subnet and the link layer address of the current position;
When the packet transferred to the own device is in an encapsulated format, the link layer address corresponding to the original network layer address of the packet obtained by decapsulation is checked with reference to the correspondence table , Means for delivering the packet resulting from the decapsulation using the link layer address;
When at least one wireless terminal is connected to a wireless base station installed in the subnet , a list of wireless base stations adjacent to the wireless base station notified from the wireless base station is received, Search for a router device that manages each wireless base station included in the list of wireless base stations, and among the searched router devices , at least other router devices installed in a subnet different from the subnet , Control indicating that the other router device should change the time interval for broadcasting the advertisement message from the first time interval to a second time interval shorter than the first time interval for a certain period of time. A means of notifying information ;
It is notified from another router device installed in a different subnet as the subnet, first the advertising messages time interval for broadcast transmission from a first time interval only during a certain time shorter than the time interval of the first On the basis of control information indicating that the time interval should be changed to a second time interval, a second time interval shorter than the first time interval is set from the first time interval to the time interval of the broadcast transmission by the transmission means for a fixed time. And a means for changing the time interval to a router device. The identification information, the wireless terminal which has moved into the subnet, according to claim 1 or characterized in that it is used to detect that it has moved to the subnet is a subnet different from the subnet that belonged to it 2. The router device according to 2. A wireless base station connected to a wireless terminal that is managed by a router device installed in each subnet that forms a network, and that can communicate by moving between subnets,
Means to hold the subnet address to which the station belongs ;
A register indicating that at least one wireless terminal is connected to the local station;
Means for notifying other wireless base stations adjacent to the own station of information including information that at least one wireless terminal is connected and the subnet address to which the own station belongs ;
When receiving information including the fact that at least one wireless terminal is connected and the subnet address to which the other wireless base station belongs, notified from another wireless base station adjacent to the own station , means for comparing the subnet address of the subnet address and the own station belongs to the different radio base station,
If the other belongs to the subnet address belongs to the subnet address and the local station of the radio base station do not match, the router that manages the own station, the advertisement message including the identification information of the router device broadcasts And means for notifying control information indicating that the time interval should be changed from the first time interval to a second time interval shorter than the first time interval for a certain period of time. Radio base station. A wireless base station connected to a wireless terminal that is managed by a router device installed in each subnet that forms a network, and that can communicate by moving between subnets,
Other wireless base stations adjacent to the local station are stored as list information together with a subnet address to which the other wireless base station belongs and flag information indicating whether the subnet address matches the subnet of the local station. Means,
A register indicating that at least one wireless terminal is connected to the local station;
Only when the register indicates that at least one wireless terminal is connected to the own station , among the other wireless base stations included in the list information, the wireless base station having a different subnet address depending on the flag information A message notification means,
When receiving the message notification from another radio base station adjacent to own station, the router that manages the own station, the router device includes identification information advertisement message transmission interval is a constant time broadcast of Means for notifying control information indicating that the first time interval should be changed to a second time interval shorter than the first time interval. A wireless terminal connected to a router device via a wireless base station and capable of communicating by moving between subnets forming a network,
A message for searching for a router device that manages a wireless base station installed in a subnet that covers the current location of the terminal itself is transmitted at a first time interval or a second time interval shorter than the first time interval. Sending means to
Based on location information indicating that at least one of the other radio base stations adjacent to the radio base station notified from the radio base station to which the device is connected belongs to a subnet different from the current subnet, A wireless terminal apparatus comprising: means for changing the time interval of transmission of the message by the transmission means from the first time interval to the second time interval for a fixed time. Based on the information of the source address included in the response message returned from the router device that has received the message, further comprising means for detecting that the terminal has moved from a subnet to which the terminal belongs to a different subnet The wireless terminal device according to claim 6 . A plurality of subnets each provided with a plurality of wireless base stations connected to wireless terminals capable of communicating by moving between subnets and router devices for transferring data packets transferred via the wireless base stations are mutually connected. A message transmission control method for a router device in a connected network,
Broadcasting an advertisement message including identification information of the own device in the subnet to which the own device belongs at a first time interval or a second time interval shorter than the first time interval,
Indicating that it is notified from a radio base station installed in the subnet, at least one wireless terminal to another wireless base station belonging to the adjacent and the subnet different from the subnet to the wireless base station is connected A message characterized in that, based on the control information, the time interval for broadcasting the advertisement message is changed from the first time interval to a second time interval shorter than the first time interval for a certain period of time. Transmission control method. A plurality of subnets each provided with a plurality of wireless base stations connected to wireless terminals capable of communicating by moving between subnets and router devices for transferring data packets transferred via the wireless base stations are mutually connected. A message transmission control method for a router device in a connected network,
Broadcasting an advertisement message including identification information of the own device in the subnet to which the own device belongs at a first time interval or a second time interval shorter than the first time interval,
When a list of wireless base stations adjacent to the wireless base station notified from the wireless base station is received when at least one wireless terminal is connected to the wireless base station installed in the subnet And searching for a router device that manages each radio base station included in the list of the radio base station group,
Among the found router device, at least the to other router devices installed in subnets and different subnet, the another router device, between the advertising messages transmission interval broadcast certain time Control information indicating that only the first time interval should be changed to a second time interval shorter than the first time interval,
The subnets and is notified from another router device installed in different subnet, shorter than the time interval of the first to the advertisement message transmission interval broadcast from a first time interval only during a certain time Based on the control information indicating that it should be changed to the second time interval, the broadcast transmission time interval by the transmission means is changed from the first time interval to the first time interval shorter than the first time interval for a fixed time. 2. A message transmission control method, wherein the time interval is changed to two time intervals. Data exchange for movement of wireless terminals between wireless base stations managed by the same router device without the change of the subnet is performed using a channel switching mechanism on the wireless link, and the wireless base station with the change of the subnet message transmission control method according to claim 8 or 9 data processing for movement between is characterized by performing the mobile IP registration and encapsulation. The identification information, the wireless terminal which has moved into the subnet, claim 8 or characterized in that it is used to detect that it has moved to the subnet is a subnet different from the subnet that belonged to it 10. The message transmission control method according to 9 .

Images