WO2006043503A1

WO2006043503A1 - Communication system for mobile body

Info

Publication number: WO2006043503A1
Application number: PCT/JP2005/019028
Authority: WO
Inventors: Kazuya Monden; Masato Hayashi; Hiroki Sato; Shoji Fukuzawa
Original assignee: Hitachi, Ltd.
Priority date: 2004-10-18
Filing date: 2005-10-17
Publication date: 2006-04-27
Also published as: JP2006115363A; JP4270096B2

Abstract

In communication for a mobile body, it is possible to provide a method for continuing communication for a mobile terminal which cannot communicate directly with a base station, without modifying the IP address. Moreover, when the mobile terminals belong to the same sub-network, it is possible to perform communication between the mobile terminals by multi-hop communication. When allocating a C/O address belonging to the sub-network to be connected, the mobile terminal which has received a router advertisement transmits the same router advertisement, thereby allocating a C/O address to the mobile terminal which cannot communicate directly with the base station. The mobile terminals constitute an ad-hoc network and realizes communication via the base station. Moreover, by routing the home address of the mobile terminal by the ad-hoc network, it is possible to realize communication between the mobile terminals in the same sub-network.

Description

Specification

Mobile communication systems

[0001] The present invention relates to mobile data communication systems, and more particularly to technology for maintaining communication while mobile terminals are moving between networks.

Background art

[0002] Generally, an IP network is configured by connecting a plurality of subnets having different IP address groups to each other, and terminals connected to the subnetwork are assigned to each subnetwork! /, An IP address is given from among the group of IP addresses. Generally, in a subnetwork, packets are transferred based on an IP address, so the mobile terminal needs to be assigned a different IP address each time it moves to another subnetwork.

[0003] Mobile terminal power using IPv4 currently being widely used as a communication protocol of the Internet and IPv6 currently spreading is widely used. IPs used in the subnetwork before moving when moving to another subnetwork Since packets addressed to the address reach the pre-move subnetwork, the post-move subnetwork can not use V and the IP address used in the pre-move subnetwork to maintain communication! /, .

[0004] In order to solve the above problems, a technology called Mobile IP has been proposed that enables communication to be maintained even when the mobile terminal moves to another subnetwork !.

For example, in Mobile IPv6 based on IPv6, a mobile terminal defines, as a home network, a subnetwork to which the mobile terminal normally belongs in the subnetwork. The mobile terminal is assigned a home address (Home Add ess) as an IP address used in the home network, and the home network has a home address having a function of managing location information of the mobile terminal whose home network is the corresponding subnetwork. Put an agent.

The upper part of the IPv6 address is assigned as a prefix address to each subnetwork. Each subnetwork is provided with at least one router called an advertisement router. The advertisement router transmits a router advertisement (Router Advertisement) including the prefix address of the relevant subnetwork to the mobile terminal in the subnetwork to inform which subnetwork has which prefix address the mobile terminal belongs to. Also, when a mobile terminal in a subnetwork requests a notification of information on the currently belonging subnetwork, it responds with the above advertisement.

Each mobile terminal acquires the prefix address of the subnetwork in the destination subnetwork from the above router advertisement, and has the address assigned by the IPv6 auto configuration function or DHCP (Dynamic Host Configuration Protocol). According to, generate a Care-of Address to be used in the destination subnetwork. The mobile terminal notifies the home agent device (hereinafter referred to as a home agent) of association information (binding update) between the created care-of address and its home address, and thereafter the home agent reaches the home address of the mobile terminal. The IPv6 packet is captured, encapsulated and sent to the care-of address, and the mobile terminal receives the packetized packet sent to the care-of address, removes the capsule, and sends it to the home address of the own terminal! , Pull out IPv6 packets.

[0008] In addition, communication is performed in a mopile network that includes a mobile terminal having a router function (a mopile router,...) And a mobile terminal that moves together with the mopile router and does not have a Mobile IP function. The standardization of the protocol that provides the continuation of the NEMO (NEtw ork Mobility) working group of the IETF is being considered!

In addition, there is a method using an ad hoc network in which multi-hop communication is performed between mobile terminals in order to communicate between the base station and the mobile terminals outside the wireless communication range of the base station. (For example, Unexamined-Japanese-Patent No. 2003-230167).

Disclosure of the invention

Problem that invention tries to solve

[0010] In the above-mentioned prior art, since one-hop connection to the base station does not take into consideration the assignment of the care-of-address to the mobile terminal, other mobile terminals may send packets to the mobile terminal. Can not. This is because the mobile terminal can not perform Binding update to the home agent, so the home agent can transmit a packet addressed to the home address of the mobile terminal to the mobile terminal. It is because it can not be transferred to.

Also, even if it is possible to communicate without using the home agent if these mobile terminals use another network such as an ad hoc network, it is possible to address the home address between these mobile terminals. The communication that takes place is via the home agent, which causes problems such as long communication paths and wasted traffic.

Means to solve the problem

The present invention provides a communication method in which a care-of address is assigned to a mobile terminal that communicates with an advertising router in two or more hops (multihop), and the mobile terminal registers the assigned care-of address in a home agent. Do.

Furthermore, the present invention makes it possible to provide a mobile terminal capable of multi-hop communication or a mobile terminal in a subnetwork moving with the mobile terminal with a communication path not via the home agent. .

Specifically, according to the present invention, an advertisement router that doubles as a base station terminal when the mobile terminal communicates with another subnetwork or home network transmits a router advertisement for care-of-address assignment. And the mobile terminal receiving the router advertisement forwards the router advertisement to another mobile terminal.

Furthermore, the present invention is characterized in that redundant communication paths are avoided by advertising on the ad hoc network the address assigned to the mobile terminal and the address of the network moving with the mobile terminal. .

More specifically, according to one aspect, a communication method according to the present invention includes a network including a mobile terminal having a communication packet transmission / reception function, and a base station terminal that communicates with the mobile terminal, and a mobile terminal In the communication system comprising a home agent that manages the base stations, each base station terminal constitutes a subnetwork to which the own terminal belongs, and a mobile terminal that can communicate with the base station terminal in one hop and a mobile terminal that can not communicate in one hop The care-of address of the subnetwork is assigned to mobile terminals that are connected to each other by wireless links and belong to the subnetwork and can communicate in one hop, and the mobile terminal that can not communicate in one hop. Communication packets addressed to mobile terminals that can not communicate are transferred to the care-of address of the subnetwork, and communication is possible with one hop. Do mobile terminal receives the communication packet It is characterized in that it can not communicate in one hop! / ヽ transfer to the mobile terminal.

Furthermore, the base station terminal advertises a network prefix address of the subnetwork, and a mobile terminal that has received the advertised network prefix address is connected to another radio terminal belonging to the subnetwork via a wireless link. In addition, the mobile terminal to which the network prefix address has been transferred and to which the network prefix address has been transferred generates a care-of address and registers with the home agent.

Furthermore, when the mobile network is further connected to the mobile terminal capable of communicating in one hop, the home agent can communicate the communication packet addressed to the mobile terminal in the mobile network in one hop. The mobile terminal capable of performing one-hop communication and transferring communication packets to the mobile network.

Furthermore, the mobile terminal belonging to the subnetwork is characterized in that it is assigned to the mobile terminal and establishes a multi-hop communication path using a care-of address.

According to another aspect, a communication method according to the present invention includes a network including a mobile terminal equipped with a communication packet transmitting / receiving function, a base station terminal communicating with the mobile terminal, and a home for managing the mobile terminal. In a communication system comprising agents, a plurality of mobile terminals belong to a subnetwork formed by base station terminals, and constitute another wireless network not via base station terminals. A mobile terminal that has received a communication packet addressed to another mobile terminal whose home network is the subnetwork to which the home agent belongs, does not pass through the home agent when another mobile terminal belongs to another wireless network. , And transfer the communication packet.

Furthermore, the mobile terminal advertises the home address of its own home network to other mobile terminals belonging to other wireless networks, and the other mobile terminals that have received the advertised home address are: When the address in the other wireless network of the mobile terminal having the home address is registered in the routing table as the transfer destination of the communication packet having the home address as the destination, and a communication packet having the home address as the destination is received, It is characterized by forwarding to an address in another wireless network.

Furthermore, when a mobile network is further connected to each of a plurality of mobile terminals that can communicate with the base station terminal, a mobile terminal that can communicate with the base station terminal is connected When a communication packet addressed to a mobile terminal in another mobile network connected to another mobile terminal capable of communicating with the base station terminal is received from a mobile terminal in the network, in the subnetwork, without passing through the home agent. The other mobile terminal capable of communicating with the base station terminal, which has transferred the communication packet to another mobile terminal capable of communicating with the base station terminal and has received the transferred communication packet, is connected to the other mobile terminal. A communication packet is transferred to a mobile terminal in a mobile network.

Furthermore, the mobile terminal includes a wireless interface for communicating with a base station and a wireless communication interface for communicating with another wireless network, and the base station terminal has a network prefix address of the subnetwork. The mobile terminal prioritizes multiple wireless interfaces and generates and updates a care-of-address when it receives an advertised network prefix address in a network using a higher priority, wireless interface. It is characterized by

According to one aspect, a mobile terminal according to the present invention is a mobile terminal having a communication packet transmitting / receiving function and belonging to a home network configured by a home agent, and is connected to a base station terminal by one hop. The mobile station belongs to a subnetwork configured by the base station terminal and connects with a mobile terminal that can not communicate with the base station terminal in one hop by a wireless link, holds the care-of-address of the subnetwork, and from the home agent It is characterized in that it receives a communication packet addressed to a mobile terminal connected to a wireless link and can not communicate in one hop, transferred to an address, and transfers the received communication packet to the mobile terminal, which can not communicate in one hop. I assume.

The mobile terminal according to the present invention has, in another aspect, a communication packet transmitting / receiving function, is a mobile terminal belonging to a home network configured by a home agent, and includes a base station terminal. Communication packets addressed to other mobile terminals that make up a subnet network to which the home agent belongs as a home network, which belongs to another mobile terminal and constitutes another wireless network that does not go through the base station terminal. It is characterized in that communication buckets are transferred to other mobile terminals using another radio network without receiving and passing through the home agent.

[0026] According to the above aspect, the mobile terminal power not connected with the base station in one hop, Even if the mobile terminal connected to the network moving with the mobile terminal moves the subnet, it is possible to generate a care-of-address belonging to the destination subnet. Furthermore, the base station and other mobile terminals on the route to the mobile terminal that has generated the care-of address can construct a route to the care-of address, and the mobile terminal that has generated the care-of address is Since Home Agent can perform Binding update, it is possible to communicate without changing the IP address.

[0027] Further, by using another network such as an ad hoc network, communication can be performed without passing through a home agent, so that communication paths can be shortened and traffic can be reduced.

Effect of the invention

According to the present invention, a mobile terminal connected with a base station with one hop can also perform communication using a care-of-address. In addition, communication paths can be shortened and traffic increase can be prevented.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a view showing an embodiment of a wireless mobile communication method of the present invention. The base station terminal 106, the base station terminal 107, and the terminal 108 are connected to the network 109, and belong to different sub-networks.

Base station terminal 106 and base station terminal 107 form a gateway (router) of the wireless network and network 109. Specifically, the base station terminal 106 is an access point of the wireless LAN network 110 equipped with a wireless LAN interface, and the base station terminal 107 communicates with the public mobile radio network (hereinafter referred to as It is a base station of the cellular network 111).

Mobile terminals 101 to 105 have both a wireless LAN interface and a cellular network interface.

An example of the hardware configuration of the terminals 101 to 107 is shown in FIG. Each terminal includes a timer B01, a CPU U02, a memory B03, a wireless LAN interface B04, a cellular network interface B05, and a wired LAN interface B06. Mobile terminals 101 to 105 are wireless Packets can be transferred using the LAN interface B04 or the cellular network interface B05 and the wired LAN interface B06.

Note that the mobile terminals 101 to 105 do not have the wired LAN interface B06, and the base station terminal 106 does not have the cellular network interface B05. The base station terminal 107 has the wireless LAN interface B04. It does not have to be.

The processing of each terminal in the following description is realized by the CPU B 02 executing a program stored in the memory B 03. The program may be freely stored in memory B03, or may be a removable storage medium or communication medium that can be used by the terminal (a network such as wired, wireless, optical, or the like, or the network). May be introduced into the memory B03 as necessary via the carrier wave or digital signal).

Hereinafter, when referring to both a mobile terminal or a base station terminal, it is simply referred to as a terminal.

Mobile terminal 101 is in a position where it can communicate with mobile terminal 102 using wireless LAN interface B04, and mobile terminal 102 communicates with mobile terminal 101, mobile terminal 103, and base station terminal 106 using wireless LAN interface B04. The mobile terminal 103 can communicate with the mobile terminal 102 using the wireless LAN interface B04 and can communicate with the base station terminal 107 using the cellular network interface B05.

The mobile terminals 104 and 105 can communicate with each other using the wireless LAN interface B04, and can communicate with the base station terminal 107 at the cellular network interface B05.

Mobile terminals 101 to 105 and base station terminal 106 establish communication routes autonomously on a wireless network.

It has an ad hoc network routing control function, and configures an ad hoc network using wireless LAN interface B04. As a routing control protocol of the ad hoc network routing software, a protocol that is being discussed in standardization in the Internet Engineering Task Force (IETF) as a routing control protocol of the ad hoc network can be used.

Terminals 101 to 106 form a wireless link with the terminals present in the communication area of each other's wireless LAN interface B04, and mobile terminals 101 to 105 are the cellular networks of base station terminal 107. If it can communicate with the network interface B05, a wireless link is formed with the base station terminal 107.

In FIG. 1, mobile terminals 101 to 103 form subnetwork 110 using base station terminal 106 and wireless LAN interface B04, and mobile terminals 103 to 105 have base station terminal 107. Belongs to the subnetwork using the cellular network interface B05. The mobile terminals 104 and 105 mutually form a wireless link using the wireless LAN interface B04.

The mobile terminals 101 to 105 are assigned home addresses with the terminal 108 as a home agent device (hereinafter referred to as HA 108) and the subnetwork 112 to which the HA 108 belongs as a home network. When connecting to the base station 106 or the network 109 to which the base station 107 belongs, the mobile terminals 101 to 105 set the care-of-address belonging to the network 109 to each terminal as an interface care-of address.

The mobile terminals 101 to 105 register one of the interface care-of addresses set in each terminal in the HA 108 as a terminal care-of address, as described later. Hereinafter, when referring to both interface care-of address or terminal care-of address, it is simply referred to as care-of address.

The terminals 101 to 106 may set an address for ad hoc routing on the wireless LAN interface B04 as a routing address that configures the ad hoc network, or are assigned to the wireless LAN interface B04 to be aware of the! / You may use an address. Further, it is assumed that the address used in this embodiment is an IPv6 address, and the wireless LAN interface B04 is assigned a routing address for an ad hoc network.

Next, a setting method of the care of address in the present embodiment will be described. The method of automatically setting the address is described in the technical document RFC 2462 published by IFTF (S. Thomson, T. Narten, IPVD Stateless Address Autoconfiguration, 1998/12,

Use the method shown at <http://www.ietf.org/rfc/rfc2462.txt ».

Base station terminal 106 and base station terminal 107 also serve as advertisement routers, and are respectively network prefixes related to wireless LAN network 110 and cellular network 111 to which the own terminal belongs. Advertises router advertisements that contain information such as

Router advertisements are technical documents published by the IETF under RFC2461 (T. Narten, E. Nordmark, W. Simpson, Neighbor Discovery for IP Version 6 (IPv6), 1998/12,

It transmits using a type of router advertisement (Router Advertisement) of the ICMP packet shown in <http: 〃 www.ietf.org/rfc/rfc2461.txt ».

The mobile terminals 101 to 105 set the care-of-address from the network prefix information included in the received router advertisement and the interface identifier given to the own terminal. The interface identifier may be set manually or as described in RFC 2373 (R. Hinden, S. Deering, IP Version D Addressing Architecture, 1998/7, <http://www.ietf.org/rfc/rfc2373.txt. The MAC address of the interface may be set based on the method shown in »The care-of address is set to the effective time included in the router advertisement, and the care-of address after the effective time is Not valid, not used as!

In the present embodiment, the mobile terminal 102 receives a router advertisement advertised by the base station terminal 106, sets a care-of address, and moves the router advertisement storing the same network information as the router advertisement with the mobile terminal 101. Transfer to terminal 103.

The transfer is realized by the mobile terminal 102 transmitting again a broadcast or multicast transmission of the router advertisement received from the base station terminal 106. The mobile terminals 101 and 103 that receive the router advertisement transferred from the mobile terminal 102 also transfer the router advertisement further.

The router advertisement transferred by the mobile terminals 101 and 103 may return to the mobile terminal 102, causing a loop and causing unnecessary traffic. In order to prevent this, the base station 106 may identify the router advertisement in the router advertisement and send it with an added ID number. Specifically, the router advertisement defined by the above RFC 2461 storing the network information may be expanded to add an ID number (202) for specifying the router advertisement to the router advertisement unit (201).

The mobile terminal 102 records the source address and ID number of the terminal 106 contained in the IP header of the received router advertisement in the router advertisement reception list, and the terminal that is the sender of the router advertisement for transfer. Broadcast as the address of the advertising router.

An example of a router advertisement reception list is shown in FIG. Source address in column 301, received in column 302 The router advertisement ID number, column 303, registers the network information included in the router advertisement.

The algorithm for forwarding router advertisements will be described using the flowchart in FIG. When the router advertisement is received (401), it is checked whether the received interface is an interface (a wireless LAN interface in the present embodiment) constituting the ad hoc network (402), and if not received by the interface constituting the ad hoc network (No at 402) Perform router advertisement reception processing (406).

[0055] If it is received by the interface that configures the ad hoc network and received /! (Yes in 402), it is checked whether there is a pair in the router advertisement reception list in which the source address of the router advertisement and the ID number match.ヽ (403), if there is a matching set in the router advertisement reception list (yes at 403), the process ends without doing anything. If there is not a matching pair (no in 403), the router advertisement forwarding with a TTL decremented by 1 (404) is transmitted by broadcast transmission or multicast transmission, and the source address and ID number are registered in the router advertisement reception list (405 And perform router advertisement reception processing (406).

According to the algorithm shown in FIG. 4, upon receiving the router advertisement from base station terminal 106, mobile terminal 102 transfers the router advertisement to the other terminal with which the wireless link is established. The mobile terminal 101, 103 receives the router advertisement transferred from the mobile terminal 102, and sets a care-of address. The mobile terminal 103 also receives the router advertisement transmitted by the base station terminal 107.

In the method of determining which network the mobile terminal 103 sets the care-of-address of a terminal to which the mobile terminal 103 belongs, priority is set to the communication interface of the mobile terminal, and the interface care-of address of the interface with high priority There is a method to use the care of mobile terminal address.

A flowchart of the router advertisement reception process shown in step 406 of FIG. 4 is shown in FIG. When the mobile terminal receives a router advertisement, it sets it as the care-of address of the receiving interface according to the method shown in the above RFC 2462 (501), higher priority than the received interface, and the interface care-of address in the care-of address list. If there is a high priority and an interface care-of-address (yes at 502), the process ends. Otherwise (No at 502), the interface care-of address with the same priority is added to the care-of address list. Check the power of the router advertisement (if yes at 503) and compare the TTL value of the received router advertisement with the TTL value of the above interface care-of address (504), and the TTL value of the received router advertisement. If S is smaller (yes at 504), the process ends.

If the TTL value is large! / (504 for no) or the interface care-of address with the same priority is not in the care-of address list (503 for no), check if there is a route to the advertisement router (505 ) If there is a route (yes at 505), update the care-of address of the mobile terminal (506).

In this embodiment, assuming that the priority of the wireless LAN interface B04 (priority 1) is higher than that of the cellular network interface B05 (priority 2), the mobile terminal 103 is the mobile terminal 102. Set the care-of address based on the network information included in the forwarded router advertisement. The mobile terminal 104 and the mobile terminal 105 set a care of address based on a router advertisement transmitted by the base station terminal 107.

In the case of forming a direct radio link with a base station terminal as in a cellular system, the existence confirmation of the route to the advertisement router confirms that the radio link is established, and as in an ad hoc network, When establishing a link by hop, the link is confirmed by checking the existence of the ad router in the routing table, or by using ping to confirm the communication with the ad router.

An example of a care-of address list provided for each mobile terminal is shown in FIG. The interface care-of address is registered in the column 601, and the valid time of the interface care-of address is registered in the column 602. In column 603, the interface priority is registered. Column 604 registers which interface the interface care-of address is. The column 605 registers the TTL of the router advertisement. A line 606 shows an example of registration of information of router advertisement transmitted by the base station terminal 106, and a line 607 shows an example of registration of information of router advertisement transmitted by the base station terminal 107.

Next, a method of establishing a communication route at a care of address according to the present embodiment will be described using the flowcharts of FIG. 1 and FIG.

When a new care of address is set (701), the mobile terminal 101 checks (702) whether the care of address is set as an interface constituting an ad hoc network, and an interface constituting an ad hoc network. If (in the present embodiment, the wireless LAN interface B04) (yes in 702), the care-of address is also used in the ad hoc network. An advertisement (703) is performed according to the advertisement method of one addressing address, a route in an ad hoc network is configured, and a Binding Update (704) is performed for the home agent HA 108.

The mobile terminal 102 also sets up a care-of address according to the above method and performs binding update on the HA 108. When the mobile terminal 102 receives the care-of address advertised by the mobile terminal 101, it registers in the routing table, and constructs a route using the care-of address.

FIG. 8 shows an example of a routing table used by the mobile terminal 102.

Column 801 shows the destination and netmask (network length), column 802 shows the next hop, and column 803 shows the interface used for transmission. A destination that is netmask force 128 indicates a host route and a destination that is 64 indicates a network route.

The line 804 indicates the host route CoAlOl / 128 to the care-of-address 101 of the mobile terminal (denoted as CoA) 101, and the next hop is a routing address for ad hoc network (denoted as AoA) 101, and the wireless LAN interface as a transmission interface. (Hereinafter WLAN) B04 shows an example registered, and line 805 shows the host route AoAl 01/128 to AoAlOl of mobile terminal 101! /, WLAN is registered as a transmission interface that can communicate directly! Here is an example.

Line 806 shows an example in which WLAN B 04 is registered as a transmission interface for terminal 106/128 which is a host route to terminal 106. Line 807 shows an example in which WLAN B 04 is registered as a transmission interface for the host route AoA 103/128 to AoA 103 of the mobile terminal 103.

Line 808 shows an example of registration of the network link CoA 102/64 to the network to which the care-of-address CoA 102 of the mobile terminal 102 belongs, line 809 shows the routing address AoA 102 for the ad hoc network of the mobile terminal 102. The network route AoA 102/64 belongs to! , Is registered and shows an example. Line 810 shows an example in which a default route is registered !.

Similarly to the above method, the terminal 106 creates a routing table so that the packet addressed to the care-of-address of the mobile terminal 101 is transferred to the mobile terminal 102.

Having received the Binding Update, the HA 108 encapsulates the IP in IP to the new Care of Address and transfers the packet addressed to the home address of the mobile terminal 101 to the terminal 106. Terminal 106 is on The packet is forwarded to the mobile terminal 102 by referring to the routing table described above. The mobile terminal 102 also transfers the packet to the mobile terminal 101 with reference to the routing table shown in FIG.

Also, when the mobile terminal does not have the highest priority interface care-of-address effective time of the care-of address list, it sets the highest priority interface care-of-address with remaining valid time as the mobile terminal care-of address. Do. The process in this case also follows the algorithm shown in the flowchart of FIG.

[0074] The advertisement method of the routing address in the ad hoc network differs depending on the routing protocol. In this embodiment, the routing described in RFC 3626 (T. Clausen, P. Jacquet, "Optimized Link State Routing Protocol (OLSR)" 2003/10, http://www.ietf.org/rfc/rfc3626.txt) Protocol Suppose that OLSR (Optimized Link State Routing) is used by extending it to IPv6 by expanding the address space handled from 32 bits to 128 bits. In OLSR, when the terminal has a plurality of addresses, one of them is defined as a main address, and the other address is defined as an interface address by advertising it as a Multiple Interface Declaration (MID) message. Build a communication path. By storing the care-of address of the terminal in the MID message, it is possible to establish a communication path for the care-of address.

Next, a method will be described in which the mobile terminals 101 to 105 communicate with each other using the ad hoc network without passing through the HA 108.

Mobile terminals 101 to 105 are set to wireless LAN interface B 04 as a routing address forming an ad hoc network, and a routing address for an ad hoc network that is a terminal (if the terminal care-of address is set) Advertise with care-of address and home address as routing address.

By storing the home address in the MID message and advertising as in the case of the terminal care-of address advertisement, the received mobile terminal can construct a communication path for the transmitted home terminal's home address. Become.

For example, in the present embodiment, the mobile terminal 104 and the mobile terminal 105 advertise a home address as one of a plurality of addresses. Therefore, the home address of the mobile terminal 105 is registered as a host route in the routing table of the mobile terminal 104. An example of the routing table of the mobile terminal 104 is shown in FIG. In FIG. 12, columns 801 to 803 are similar to FIG.

Line C 04 shows an example in which the next hop is AoA 105 and the transmission interface is registered as WLAN B 04 for the host route HoA 105/128 to the home address (denoted as HoA) 105 of mobile terminal 105 line C 05 is An example in which WLAN B 04 is registered as a transmission interface that can directly communicate with host route AoA 105/128 to AoA 105 of mobile terminal 105 is shown.

Row C06 shows an example in which the next hop is AoA 105 and WLAN B 04 is registered as a transmission interface for host route CoA 105/128 to CoA 105 of mobile terminal 105.

Line C07 shows an example of registration of the network route CoA 104/64 to the network to which the terminal care-of-address CoA 104 of the mobile terminal 104 belongs. Line C08 shows an example of registration to the network to which the AoA 104 of the mobile terminal 104 belongs. An example of network route AoA 104/64 registered /! Is shown. Line 809 shows an example in which a default route is registered !.

When transmitting a packet to the host address of the mobile terminal 105, the mobile terminal 104 scans the routing table shown in FIG. 12 and transmits the packet from the most appropriate interface. That is, since the home address of the mobile terminal 105 is registered in the row C04 of the routing table, a packet addressed to the home address of the mobile terminal 105 is transmitted from the wireless LAN interface B04 to the routing address for the ad hoc network, The mobile terminal 105 is reached without passing through.

Next, in the present embodiment, there is a mopile network that moves with the mobile terminal, and the mobile terminal is a mono router having a router function of the mopile network and an external network. This will be described using FIG. The configuration example of the mopile router is the same as that shown in FIG.

The mobile terminals 901 to 905 are mopile routers 901 to 905, and mopile networks 906 to 910 are connected to each other! /. The network prefix of the mopile network is set in advance.

In the present embodiment, the mopile router is connected to the mobile network by the wired LAN using the wired LAN interface B06. Mopile router and mopile network The connection method is not limited to the wired LAN as long as the mobile terminal in the mopile network can communicate with the mobile router.

When the mobile terminal is a mopile router, HA 108 manages not only the home address and the terminal care-of-address but also the network preference of the mopile network connected to the mopile router. The network prefix of the mopile network may be sent to the HA 108 in addition to the terminal care-of address at the time of Binding Update shown in the flow chart 704 of FIG. 7 and registered to the HA 108 in advance. !, Even!

In the present embodiment, when a packet is transmitted from a mobile terminal in the mopile network 906 to a mobile terminal in the mopile network 910, for example, the mopile router 901 transfers the packet to the HA 108. The HA 108 encapsulates IP in IP and forwards the packet to the mopile router 905 for forwarding to the mopile network 910. Mobile router 905 decapsulates and forwards the packet to mopile network 910.

In the conventional method, a packet transmitted from a mobile terminal in mopile network 909 to a mobile terminal in mopile network 910 has a power to reach monolile network 910 through a route via HA 108. In the present embodiment, as shown below, mobile terminals in the mopile network 910 are reached via the ad hoc network configured between the mopile routers 904 and 905 without going through the HA 108.

[0090] When the mobile terminal is a router (gateway) to a certain network, the OLSR is configured to establish a route via the own terminal on the ad hoc network. Association) stores the address of the above network in the message and advertises it. In the present embodiment, the mopile routers 904, 905 advertise the netware network of the mopile networks 909, 910 connected to the respective mopile routers as HNA messages.

FIG. 10 is an example of a routing table of the mopile router 904 that has received the advertised network prefix, and the network prefix (denoted as MoA) 910/64 of the mopile network 910 is shown in the routing table of FIG. Route AO 1 and route A02 to MoA 909/64 for mopile nets 909 have been added! A wired LAN interface (denoted as ethO) is used for connection to the mopile network 909. When the mopile router 904 receives a packet sent from a mobile terminal in the mopile network 909 to a node in the mopile network 910, it checks the routing table shown in FIG. Then, in order to deliver the packet to the mopile network 910, the packet is forwarded to the routing address AoA 905 for the ad hoc network of the mopile router 905, and the mopile router 905 forwards the forwarded packet to the mopile network 910.

As described above, communication between mopile networks without passing through the HA 108 becomes possible.

Although the above description has been made with respect to the examples, it is apparent to those skilled in the art that the present invention is not limited thereto, and various changes and modifications can be made within the spirit of the present invention and the scope of the appended claims.

Brief description of the drawings

[FIG. 1] A diagram showing an example of the configuration of a mobile terminal network.

[FIG. 2] A diagram showing an example of the format of a router advertisement.

FIG. 3 shows an example of a router advertisement reception list.

[FIG. 4] A flowchart showing an example of router advertisement transfer processing.

[FIG. 5] A flowchart showing an example of router advertisement reception processing.

FIG. 6 is a diagram showing an example of a care-of address list provided in a mobile terminal.

[FIG. 7] A flowchart showing an example of mobile terminal care-of-address change processing.

FIG. 8 shows an example of a routing table of a mobile terminal.

[FIG. 9] A diagram showing an example of the configuration of a mobile router network.

[FIG. 10] A diagram showing an example of a routing table of a mopile router.

[Fig. 11] This is an example of hardware configuration of each terminal.

FIG. 12 shows another example of a routing table of a mobile terminal.

Claims

The scope of the claims

[1] A communication method in a communication system, comprising: a network comprising a mobile terminal having a function of transmitting and receiving communication packets; a base station terminal communicating with the mobile terminal; and a home agent managing the mobile terminal.

Each of the base station terminals constitutes a subnetwork to which the own terminal belongs, and the mobile terminal capable of communicating with the base station terminal in one hop can not communicate in one hop! The mobile terminals are mutually connected by a wireless link A care-of address of the subnetwork is assigned to the mobile terminal that belongs to the subnetwork and can not communicate in the one hop, and the mobile terminal that can not communicate in the one hop;

The home agent can not communicate in the one hop! /, And transfers a communication packet addressed to the mobile terminal to the care-of address of the subnetwork,

The mobile terminal capable of communicating by one hop receives the communication packet and can not communicate by one hop, and transfers it to the mobile terminal.

A communication method characterized by

[2] In the communication method according to claim 1,

The base station terminal advertises a network prefix address of the subnetwork,

The mobile terminal receiving the advertised network prefix address forwards the network prefix address to other mobile terminals belonging to the subnetwork connected by the wireless link,

The mobile terminal to which the network prefix address has been transferred generates the care-of address,

Register with the home agent

A communication method characterized by

[3] In the communication method according to claim 1,

When a mobile network is further connected to the mobile terminal that can communicate in the one hop, the home agent is configured to communicate with the communication terminal addressed to the mobile terminal in the mobile network. Forward the packet to the mobile terminal capable of communicating in the one hop,

The mobile terminal capable of communicating in one hop transmits the communication packet to the mobile network.

A communication method characterized by

[4] In the communication method according to claim 1,

The mobile terminals belonging to the subnetwork are

Assign multi-hop communication route using care-of address assigned to mobile terminal

A communication method characterized by

[5] A communication method in a communication system, comprising: a network comprising a mobile terminal having a communication packet transmitting / receiving function; a base station terminal for communicating with the mobile terminal; and a home agent for managing the mobile terminal.

The plurality of mobile terminals belong to a subnetwork configured by the base station terminal, and mutually configure another wireless network not via the base station terminal, and the subnetwork to which the home agent belongs The mobile terminal that has received the communication packet addressed to the mobile terminal other than the home network does not pass through the home agent when the other mobile terminal belongs to the other wireless network. Forwarding the communication packet

A communication method characterized by

[6] In the communication method according to claim 5,

The mobile terminal advertises the home address of its own home network to other mobile terminals belonging to the other wireless network,

The other mobile terminal that has received the advertised home address routes the address in the other wireless network of the mobile terminal having the home address as a transfer destination of a communication packet having the home address as a destination. Register in the table, and transfer to the address in the other wireless network when a communication packet addressed to the home address is received.

A communication method characterized by

[7] In the communication method according to claim 5,

When a mobile network is further connected to each of a plurality of mobile terminals capable of communicating with the base station terminal:

A mobile terminal capable of communicating with the base station terminal is connected to another mobile network connected to another mobile terminal capable of communicating with the base station terminal from a mobile terminal in the mobile network connected to the base station terminal. When the communication packet addressed to the mobile terminal is received, the subnetwork transfers the communication packet to another mobile terminal communicable with the base station terminal without passing through the home agent.

The other mobile terminal capable of communicating with the base station terminal, having received the transferred communication packet, transfers the communication packet to the mobile terminal in the other mobile network connected thereto.

A communication method characterized by

[8] In the communication method according to claim 6,

The mobile terminal comprises a wireless interface for communicating with the base station and a wireless communication interface for communicating in the other wireless network,

The mobile terminal prioritizes the plurality of wireless interfaces,

Generate and update the care-of address when the advertised network prefix address in a network using a higher priority wireless interface is received

A communication method characterized by

[9] A mobile terminal having a function of transmitting and receiving communication packets and belonging to a home network link configured by a home agent,

It is connected to the base station terminal by the one hop, and belongs to a subnetwork configured by the base station terminal,

The mobile terminal can not communicate with the base station terminal in one hop, and is connected to the mobile terminal via a wireless link, and holds the care-of address of the subnetwork. Receiving, from the home agent, a communication packet addressed to a mobile terminal that can not communicate in the one hop, which is transferred to the care-of address of the subnetwork and connected by the wireless link;

A mobile terminal characterized in that the received communication packet is transferred to a mobile terminal that can not communicate in the one hop.

A mobile terminal that has a function of sending and receiving communication packets, and belongs to a home network link configured by a home agent.

Belongs to a subnetwork configured by the base station terminal,

Another mobile terminal and another wireless network not via the base station terminal are configured.

Receiving a communication packet addressed to the other mobile terminal whose home network is the subnetwork to which the home agent belongs;

Forwarding the communication packet to another mobile terminal using the other wireless network without passing through the home agent

A mobile terminal characterized by