JP2007267407A - Communication terminal and repeater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication terminal which performs seamless handover between communication systems using different radio communication systems by selecting a radio interface in a favorable communication state easily and appropriately. <P>SOLUTION: The communication terminal performs packet communication selectively using two different radio communication systems in a network of a predetermined address system. The terminal comprises: a first radio communication part to which a first address in the predetermined address system is allocated, and which performs radio communication using a first radio communication system; a second radio communication part to which a second address in the predetermined address system is allocated, and which performs radio communication using a second radio communication system; a communication system selector which selects a radio communication part in a favorable communication state from among the first and the second radio communication parts; and an address converter which uses the first address or the second address allocated to the first or the second radio communication part selected by the communication system selector as a sender's address of a packet to be sent. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a communication terminal and a communication system. In particular, the present invention relates to a communication terminal that performs packet communication by selectively using two different wireless communication methods.

With the spread of the Internet in recent years, various communication system technologies such as a wireless LAN (Local Area Network) system and a PHS (Personal Handyphone System) have been developed. Therefore, there has been proposed a communication terminal that has a plurality of communication interfaces suitable for each communication method of various communication systems and performs communication by automatically switching the communication interface based on the communication environment (for example, Patent Documents). 1).
JP 2001-309445 A (FIG. 1)

  When a plurality of communication systems with different communication methods are selectively used, it is necessary to perform seamless handover between the different communication systems. For this purpose, it is a problem to simply and appropriately select a communication interface suitable for the communication system. It becomes.

  Then, this invention aims at providing the communication terminal and communication system which can solve said subject. This object is achieved by a combination of features described in the independent claims. The dependent claims define further advantageous specific examples of the present invention.

  That is, according to the first aspect of the present invention, the communication terminal performs packet communication by selectively using two different wireless communication methods in a network having a predetermined address system. The communication terminal is assigned a first address in a predetermined address system, and is assigned a first wireless communication unit that performs wireless communication in the first wireless communication system, and a second address in the predetermined address system, and the second wireless communication system A second wireless communication unit that performs wireless communication, a communication method selection unit that selects a wireless communication unit having a good communication state among the first wireless communication unit and the second wireless communication unit, and a source address of a packet to be transmitted And an address conversion unit using the first address or the second address assigned to the first wireless communication unit or the second wireless communication unit selected by the communication method selection unit as a transmission source address.

  According to the second aspect of the present invention, the communication terminal includes a relay device that connects the internal network of the first address system and the external network of the second address system, the first radio base station that performs radio communication in the internal network, and In a communication system including a second radio base station, wireless communication is performed with the first radio base station or the second radio base station in the internal network, and the external communication is performed via the first radio base station or the second radio base station and the relay device. Communicate over the network.

  The communication terminal is assigned a first internal address that is an address of the first address system, and a first wireless communication unit that performs wireless communication with the first wireless base station using the first wireless communication method in the internal network, and a first address system A second internal address that is an address of the second wireless communication unit that performs wireless communication with the second wireless base station by the second wireless communication method in the internal network, and the first wireless communication unit and the second wireless communication unit Among them, a communication method selection unit that selects a wireless communication unit with a good communication state, and a first wireless that the communication method selection unit selects a source address of a packet that includes an external address that is an address of the second address system as data. As the first internal address or the second internal address assigned to the communication unit or the second wireless communication unit, the first wireless base is connected to the first wireless communication unit or the second wireless communication unit. Or comprising an address conversion unit for transmitting to the relay apparatus via the second radio base station.

  According to the third aspect of the present invention, the communication system includes a relay device that connects the internal network of the first address system and the external network of the second address system, and is connected to the relay device in the internal network, and the first wireless A first wireless base station that performs wireless communication by a communication method; a second wireless base station that is connected to a relay device in the internal network and performs wireless communication by a second wireless communication method; and a first wireless base station or a second wireless base station Communication that performs wireless communication with a base station and performs packet communication in an external network via a first wireless base station or a second wireless base station and a relay device, and is assigned an external address that is an address of a second address system A terminal.

  The communication terminal is assigned a first internal address that is an address of the first address system, and a first wireless communication unit that performs wireless communication with the first wireless base station using the first wireless communication method, and an address of the first address system. A communication state is good among a second wireless communication unit that is assigned a second internal address and performs wireless communication with the second wireless base station in the second wireless communication method, and the first wireless communication unit and the second wireless communication unit. A communication method selection unit that selects an appropriate wireless communication unit, and a first address assigned to the first wireless communication unit or the second wireless communication unit selected by the communication method selection unit, as a transmission source address of a packet that includes an external address as data A communication terminal address conversion unit that causes the first wireless communication unit or the second wireless communication unit to transmit the internal address or the second internal address.

  The relay device includes an external communication unit that performs communication in an external network, an internal communication unit that performs communication in an internal network, and a source address of a packet that the internal communication unit has acquired from the first radio base station or the second radio base station. And a relay device address conversion unit that causes the external communication unit to transmit the external address included in the packet.

  The above summary of the invention does not enumerate all the necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

  As is clear from the above description, according to the present invention, there is provided a communication terminal and a communication system that perform simple handover between communication systems with different wireless communication methods by simply and appropriately selecting a wireless interface unit having a good communication state. Can be provided.

  Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the claims, and all combinations of features described in the embodiments are included. It is not necessarily essential for the solution of the invention.

  FIG. 1 shows an example of the configuration of a communication system according to an embodiment of the present invention. The communication system includes a gateway GW 100 that connects a local network and a global network, a wireless LAN access point AP 200 that is connected to the gateway GW 100 in the local network and performs wireless communication by a wireless LAN communication method, and a gateway GW 100 in the local network. A PHS master station CS300 that is connected and wirelessly communicates using the PHS communication method, and a multi-service terminal MS400 that wirelessly communicates with the wireless LAN access point AP200 or the PHS master station CS300. The multi-service terminal MS400 is assigned a global IP address which is an address of the global IP address system, and performs packet communication in the global network via the wireless LAN access point AP200 or the PHS master station CS300 and the gateway GW100.

  The multi-service terminal MS400 is assigned a first local IP address that is an address of the local IP address system, and a wireless LAN interface unit 402 that performs wireless communication with the wireless LAN access point AP200 by a wireless LAN communication method, and a first local IP address A PHS interface unit 404 that is assigned a second local IP address different from the PHS communication method and performs wireless communication with the PHS master station CS 300 in the PHS communication method, and a wireless interface having a good communication state among the wireless LAN interface unit 402 and the PHS interface unit 404 A communication method selection unit 406 that selects a unit, an application unit 408 that generates a packet having a global IP address assigned to the multi-service terminal MS 400 as a destination address, and an application Wireless LAN interface unit by adding the first local IP address or the second local IP address assigned to the wireless LAN access point AP200 or PHS master station CS300 selected by the communication method selection unit 406 to the packet generated by the communication unit 408 402 or an address conversion unit 410 that causes the PHS interface unit 404 to transmit. That is, the address conversion unit 410 allocates the source address of the packet including the global IP address assigned to the multi-service terminal MS400 as data to the wireless LAN access point AP200 or the PHS master station CS300 selected by the communication method selection unit 406. As the first local IP address or the second local IP address, the wireless LAN interface unit 402 or the PHS interface unit 404 is transmitted to the gateway GW 100 via the wireless LAN access point AP200 or the PHS master station CS300.

  The gateway GW 100 includes a global IP processing unit 102 that performs communication in the global network, a local IP processing unit 104 that performs communication in the local network, and packets acquired by the local IP processing unit 104 from the wireless LAN access point AP200 or the PHS master station CS300. As the global IP address included in the packet as the data, the address conversion unit 106 that transmits to the global IP processing unit 102, the local IP address converted by the address conversion unit 106, and the global IP address are stored in association with each other And an address storage unit 108.

  According to the communication system of the present embodiment, the multi-service terminal MS400 selectively uses two different wireless communication methods in a network having a predetermined address system, and performs packet communication using a wireless communication method with a good communication state. be able to.

  The local network is an example of the internal network of the first address system of the present invention, and the global network is an example of the external network of the second address system of the present invention. Specifically, the local network has a local IP address system, and the global network has a global IP address system. The global IP address is an example of the external address of the present invention, and the local IP address is an example of the internal address of the present invention.

  The wireless LAN access point AP200 is an example of the first wireless base station of the present invention, and the wireless LAN communication system is an example of the first wireless communication system of the present invention. The wireless LAN communication system is a system defined by, for example, IEEE 802.11. The PHS master station CS300 is an example of the second radio base station of the present invention, and the PHS communication system is an example of the second radio communication system of the present invention.

  Multi-service terminal MS400 is an example of the communication terminal of the present invention. The wireless LAN interface unit 402 is an example of a first wireless communication unit of the present invention, and the PHS interface unit 404 is an example of a second wireless communication unit of the present invention. The address conversion unit 410 is an example of a communication terminal address conversion unit of the present invention.

  The gateway GW 100 is an example of the relay device of the present invention. The global IP processing unit 102 is an example of the external communication unit of the present invention, and the local IP processing unit 104 is an example of the internal communication unit of the present invention. The address conversion unit 106 is an example of the relay device address conversion unit of the present invention.

  FIG. 2 shows a data format of packets exchanged in the communication system according to the present embodiment. FIG. 3 shows an example of the data format of the address storage unit 108 according to the present embodiment. The application unit 408 adds a global IP header 600 having a global IP address assigned to the multi-service terminal MS400 as a transmission source address to the IP data 602, generates a global IP packet 604, and supplies it to the address conversion unit 410. The global IP header 600 becomes a header part of the global IP packet 604, and the IP data 602 becomes a data part of the global IP packet 604.

  The address conversion unit 410 encapsulates the global IP packet 604 acquired from the application unit 408, and uses the local IP header 606 with the local IP address assigned to the wireless LAN interface unit 402 or the PHS interface unit 404 as a transmission source address. The local IP packet 608 is generated by adding to the packet and supplied to the wireless LAN interface unit 402 or the PHS interface unit 404. The local IP header 606 is a header part of the local IP packet 608, and the global IP header 600 and the IP data 602 are data parts of the local IP packet.

  Further, the address conversion unit 410 removes the local IP header 606 of the local IP packet 608 acquired from the wireless LAN interface unit 402 or the PHS interface unit 404, generates a global IP packet 608, and supplies the global IP packet 608 to the application unit 408.

  The address translation unit 108 removes the local IP header 606 from the local IP packet 608 acquired from the local IP processing unit 104, generates a global IP packet 604, and supplies the global IP packet 604 to the global IP processing unit 102. At this time, as shown in FIG. 3, the address storage unit 108 is the transmission source address of the global IP header 600, the global IP address assigned to the multi-service terminal MS 400, and the transmission source address of the local IP header 606. The local IP address assigned to the wireless LAN interface unit 402 or the PHS interface unit 404 is stored in association with each other.

  In addition, the address conversion unit 108 encapsulates the global IP packet 604 acquired from the global IP processing unit 102, and the local IP address that the address storage unit 108 stores in association with the transmission source address of the global IP header 600 is the transmission source address. A local IP header 606 is added to the global IP packet 604, and a local IP packet 608 is generated and supplied to the local IP processing unit 104.

  According to the communication system of the present embodiment, the multi-service terminal MS400 can perform packet communication in the global network using the assigned global IP address even when communicating in the local network. .

  FIG. 4 shows an example of a communication method selection method by the communication method selection unit 406 according to the present embodiment. The graph shown in FIG. 4 shows the relationship between the location of the multi-service terminal MS400 and the electric field level generated by the wireless LAN access point AP200 or the PHS master station CS300. In addition, the threshold value of the electric field level serving as an index for selecting the wireless interface unit by the communication method selection unit 406 is shown.

  The communication method selection unit 406 detects the electric field level received by the wireless LAN interface unit 402 from the wireless LAN access point AP200 and the electric field level received by the PHS interface unit 404 from the PHS master station CS300. Then, the communication method selection unit 406 determines that the communication state of the wireless interface unit having a large received electric field level from the wireless LAN interface unit 402 and the PHS interface unit 404 is good.

  For example, when the multi-service terminal MS400 exists at the location A, the electric field level received from the wireless LAN access point AP200 is larger than the threshold value, and the electric field level received from the PHS interface unit 404 is smaller than the threshold value. Selects the wireless LAN interface unit 402. Then, the address conversion unit 410 causes a local IP packet to be transmitted from the wireless LAN interface unit 402 to the wireless LAN access point AP200 using the local IP address assigned to the wireless LAN interface unit 402 as a transmission source address. Further, when multi-service terminal MS 400 is present at location B, the electric field level received from wireless LAN access point AP 200 is smaller than the threshold value, and the electric field level received from PHS interface unit 404 is larger than the threshold value. Selects the PHS interface unit 404. Then, the address conversion unit 410 transmits a local IP packet from the PHS interface unit 404 to the PHS master station CS 300 using the local IP address assigned to the PHS interface unit 404 as a transmission source address.

  In another example, the communication method selection unit 406 detects an error rate of communication between the wireless LAN interface unit 402 and the wireless LAN access point AP200 and an error rate of communication between the PHS interface unit 404 and the PHS master station CS300. May be. Then, the communication method selection unit 406 may determine that the communication state of the wireless interface unit with a small error rate is good among the wireless LAN interface unit 402 and the PHS interface unit 404.

  According to the multi-service terminal MS400 of the present embodiment, since the wireless interface unit is selected according to the electric field level received by the wireless LAN interface unit 402 and the PHS interface unit 404, the wireless interface unit having a good communication state is selected. Can always perform communication with good quality.

  FIG. 5 shows an outline of a communication flow of the communication system according to the present embodiment. Steps 1-1, 2-1, 3-1, and 4-1 are communication flows when the wireless LAN interface unit 402 and the wireless LAN access point AP200 are used. Steps 1-2, 2-2, 3-2, and 4-2 are communication flows when the PHS interface unit 404 and the PHS master station CS300 are used. With reference to FIG. 6, FIG. 7, FIG. 8, and FIG. 9, the operation flow of the multi-service terminal MS400 or the gateway GW 100 in each step shown in FIG.

  FIG. 6 shows an operation flow of the multi-service terminal MS400 in step 1-1 or 1-2. The application unit 408 adds a global IP header with the global IP address assigned to the multi-service terminal MS400 as a transmission source address to the IP data, generates a global IP packet, and passes it to the address translation unit 410 (step 10). Then, the communication method selection unit 406 selects a radio interface unit that is equal to or higher than a threshold among the electric field level received by the wireless LAN interface unit 402 from the wireless LAN access point AP200 and the electric field level received by the PHS interface unit 404 from the PHS master station CS300. The wireless LAN interface unit 402 or the PHS interface unit 404 is selected (step 12).

  In step 12, when the communication method selection unit 406 selects the wireless LAN interface unit 402, the address conversion unit 410 transmits the local IP header for the wireless LAN, that is, the local IP address assigned to the wireless LAN interface unit 402 as the transmission source. A global IP packet generated by the application unit 408 is encapsulated with a local IP header as an address to generate a local IP packet (step 14).

  In step 12, when the communication method selection unit 406 selects the PHS interface unit 404, the address conversion unit 410 uses the local IP header for PHS, that is, the local IP address assigned to the PHS interface unit 404 as a transmission source address. The global IP packet generated by the application unit 408 is encapsulated with the local IP header to generate a local IP packet (step 16).

  Then, the wireless LAN interface unit 402 or the PHS interface unit 404 sends out the local IP packet generated by the address conversion unit 410 (step 18).

  FIG. 7 shows an operation flow of the gateway GW 100 in step 2-1 or 2-2. The address translation unit 106 removes the local IP header from the local IP packet received by the local IP processing unit 104 and generates a global IP packet (step 20). Then, the address conversion unit 106 registers a set of the local IP address that is the transmission source address of the local IP header and the global IP address that is the transmission source address of the global IP header in the address storage unit 108 (step 22). Then, the global IP processing unit 102 transmits a global IP packet to the global network and transmits it to the correspondent node CN 500 (step 24).

  FIG. 8 shows an operation flow of the gateway GW 100 in step 3-1 or 3-2. The address conversion unit 106 is configured so that the address storage unit 108 correlates to the global IP address from the global IP address that is the transmission source address of the global IP header of the global IP packet received from the correspondent node CN 500 by the global IP processing unit 102. The local IP address to be stored is acquired (step 30). Then, the address conversion unit 106 encapsulates the global IP packet acquired by the global IP processing unit 102 with the local IP header including the acquired local IP address, and generates a local IP packet (step 32). Then, the local IP processing unit 104 transmits a local IP packet to the local network and transmits it to the multi-service terminal MS400 via the wireless LAN access point AP200 or the PHS master station CS300 (step 34).

  FIG. 9 shows an operation flow of the multi-service terminal MS400 in step 4-1 or 4-2. The address conversion unit 410 removes the local IP header of the local IP packet received by the wireless LAN interface unit 402 or the PHS interface unit 404 and generates a global IP packet (step 40). Then, the application unit 408 processes the global IP packet generated by the address translation unit 410 (step 42).

  According to the communication system of the present embodiment, the multi-service terminal MS400 simply and appropriately selects a wireless interface unit having a good communication state from the wireless LAN interface unit 402 and the PHS interface unit 404, and the wireless LAN system and the PHS. Can be seamlessly handed over.

  FIG. 10 shows an example of the hardware configuration of the multi-service terminal MS400 according to the present embodiment. The multi-service terminal MS400 includes a CPU 700, ROM 702, RAM 704, communication interface 706, hard disk drive 708, database interface 710, flexible disk drive 712, and CD-ROM drive 714. The CPU 700 operates based on a program stored in the ROM 702 and the RAM 704 and controls each unit. The communication interface 706 communicates with other communication devices via a local network. The database interface 710 writes data into the database and updates the contents of the database.

  The flexible disk drive 712 reads data or a program from the flexible disk 720 and provides it to the CPU 700. The CD-ROM drive 714 reads data or a program from the CD-ROM 722 and provides it to the CPU 700. The database interface 710 is connected to various databases 724 to transmit / receive data.

  The program provided to the multi-service terminal MS400 is stored in a recording medium such as the flexible disk 720 or the CD-ROM 722 and provided by the user. The program stored in the recording medium may be compressed or uncompressed. The program is read from the recording medium and executed by the CPU 700.

  A program stored and provided in a recording medium, that is, a program installed in the multi-service terminal MS 400 includes a wireless LAN interface module, a PHS interface module, a communication method selection module, an application module, and an address conversion module as functional configurations. . The operation that each module causes the multi-service terminal MS400 to perform is the same as the operation of the corresponding member in the multi-service terminal MS400 described with reference to FIGS.

  The flexible disk 720 or the CD-ROM 722 as an example of the recording medium can store a part or all of the functions of the multi-service terminal MS 400 in all the embodiments described in the present application.

  These programs may be read directly from the recording medium into the RAM 704 and executed, or once installed in the hard disk, read out into the RAM and executed. Further, the program may be stored in a single recording medium or a plurality of recording media. Further, it may be stored in a form encoded by encryption, compression, or the like.

  As recording media, in addition to flexible disks and CD-ROMs, optical recording media such as DVD and PD, magneto-optical recording media such as MD, tape media, magnetic recording media, semiconductor memories such as IC cards and miniature cards, etc. Can be used. Alternatively, a storage device such as a hard disk or RAM provided in a server system connected to a dedicated communication network or the Internet may be used as a recording medium, and the program may be provided to the multi-service terminal MS400 via a local network.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. Various modifications or improvements can be added to the above embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

It is a figure which shows an example of a structure of a communication system. It is a figure which shows the data format of the packet transmitted / received in a communication system. 3 is a diagram illustrating an example of a data format of an address storage unit 108. FIG. 6 is a diagram illustrating an example of a communication method selection method by a communication method selection unit 406. FIG. It is a figure which shows the outline | summary of the communication flow of a communication system. It is a figure which shows the operation | movement flow of multi service terminal MS400 in step 1-1 or 1-2. It is a figure which shows the operation | movement flow of the gateway GW100 in step 2-1 or 2-2. It is a figure which shows the operation | movement flow of the gateway GW100 in step 3-1 or 3-2. It is a figure which shows the operation | movement flow of multi service terminal MS400 in step 4-1 or 4-2. It is a figure which shows an example of the hardware constitutions of multi service terminal MS400.

Explanation of symbols

100 Gateway GW
102 Global IP Processing Unit 104 Local IP Processing Unit 106 Address Translation Unit 108 Address Storage Unit 200 Wireless LAN Access Point AP
300 PHS master station CS
400 Multi-service terminal MS
402 Wireless LAN interface unit 404 PHS interface unit 406 Communication method selection unit 408 Application unit 410 Address conversion unit 500 Communication partner node CN
600 Global IP header 602 IP data 604 Global IP packet 606 Local IP header 608 Local IP packet 700 CPU
702 ROM
704 RAM
706 Communication interface 708 Hard disk drive 710 Database interface 712 Flexible disk drive 714 CD-ROM drive 720 Flexible disk 722 CD-ROM
724 Databases

Claims (2)

A communication terminal having an IP address in a global network, having a plurality of communication interfaces to which an IP address different from the IP address is assigned in order to connect to the IP network;
When transmitting an IP packet, a first IP packet to which an IP header having an IP address in the global network as a source address is added is generated, one of the plurality of communication interfaces is selected, and the selected communication is selected. An IP header having the IP address assigned to the interface as a source address, encapsulating the first IP packet to generate a second IP packet, and sending the second IP packet using the selected communication interface;
A communication terminal, wherein when receiving an IP packet, an IP packet generated by removing an IP header from an IP packet received by any of the plurality of communication interfaces is passed to an application unit. A relay device for causing a communication device having a plurality of interfaces assigned IP addresses to connect to an IP network to perform packet communication with the global network,
A packet transmitted from one interface of the plurality of interfaces of the communication device, including an IP address in the global network of the communication device as data, and the address system of the internal network to which the interface belongs to the interface Based on an IP packet whose source address is the assigned address, the IP address assigned to the interface that transmitted the IP packet and the IP address in the global network of the communication device are stored in association with each other,
A relay apparatus, wherein an IP packet received from a global network and destined for an IP address in the global network of the communication apparatus is encapsulated with an IP header including an IP address assigned to the interface and transmitted.

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