JP2005124087A - Mobile terminal and mobile terminal control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten a series of processing time at the time of hand-over by continuing connection to the Internet without interruption or the like of data transmission/reception even when the BSS of a mobile terminal connected to the Internet via a wireless LAN system is changed by the hand-over. <P>SOLUTION: A mobile terminal 10 includes: a radio communication section 12; an Internet communication section 14; a detection section 16 for detecting the change of the BSS 30 when the mobile terminal 10 is handed over; and a control section 18 for inquiring a DHCP server 60 of subnet information while continuing data transmission/reception when the change of the BSS 30 is detected, acquiring a new IP address from the DHCP server 60 when a subnet 40 is different from a subnet before the change of the BSS 30, and controlling the Internet communication section 14 for Internet connection using the IP address. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a mobile terminal that performs wireless communication conforming to IPv4 via a wireless LAN system, and a mobile terminal control method for controlling the mobile terminal.

  Conventionally, a mobile terminal can be connected to the Internet via a wireless LAN (Local Area Network) system for wireless connection to an access point. The mobile terminal and the access point are connected by a wireless LAN protocol, and connected to the Internet (communication conforming to IPv4 (Internet Protocol Version 4)) by TCP / IP (Transmission Control Protocol / Internet Protocol).

  Among these, for a wireless LAN, a mobile terminal establishes wireless LAN communication by belonging to a BSS (Basic Service Set) of an access point in the wireless LAN system. When a mobile terminal moves and enters an area of a different BSS, a handover can be automatically performed to switch to the access point of the different BSS, and communication can be continued.

Connection to the Internet is made possible by a DHCP (Dynamic Host Configuration Protocol) server setting an IP address (private address) in a mobile terminal via an access point. By the way, in order to efficiently perform network management and distribution of circuit resources in large enterprises, there are cases where a network is divided into several subnets (networks of management units) and set and managed. An IP address is set for each subnet, and in a certain subnet, connection to the Internet cannot be made using an IP address set in another subnet (see Patent Document 1 below).
JP 2000-156682 A

  In a wireless LAN system, a subnet is composed of one or a plurality of BSSs. Therefore, when a mobile terminal performs a handover, the subnet may be different. In that case, the IP address set in the mobile terminal becomes unable to connect to the Internet or causes confusion in the network. As a result, data communication is interrupted, and a series of processing during handover takes time. There was a problem that.

  The present invention has been made to solve the above problems, and interrupts data transmission / reception even when a mobile terminal connected to the Internet via a wireless LAN system changes its BSS due to handover. It is an object of the present invention to provide a mobile terminal and a mobile terminal control method that can continue to connect to the Internet without being equalized and can shorten a series of processing times during handover.

  In order to achieve the above object, a mobile terminal according to the present invention is a mobile terminal that performs wireless communication conforming to IPv4 via a wireless LAN system, and that the BSS has been changed due to handover of the own terminal. When the BSS change is detected by the detection means to be detected, the subnet information is inquired to the DHCP server while continuing to transmit and receive data, and the subnet found by the inquiry is a different subnet from that before the BSS change. In this case, the apparatus includes a control unit that obtains a new IP address from the DHCP server and performs Internet control using the IP address.

  In the mobile terminal according to the present invention, when the own terminal performs a handover, the detecting means detects a change in the BSS due to the handover. When the detection is made, the control means inquires the DHCP server about the subnet information while continuing to transmit and receive data. When the subnet found by the inquiry is a different subnet from that before the change of the BSS, a new one is obtained from the DHCP server. An IP address is acquired, and control for connecting to the Internet using the IP address is performed.

  As a result, the mobile terminal according to the present invention can continue to connect to the Internet without interrupting data transmission / reception when the subnet is the same when the BSS is changed by handover, and the subnet is different. Even in such a case, a series of processing time at the time of handover can be shortened without interrupting data transmission / reception, and a new IP address can be automatically acquired and connected to the Internet.

  Further, the present invention can be described as an invention of a mobile terminal control method as follows, in addition to being described as an invention of a mobile terminal as described above. This is substantially the same invention only in different categories and has the same effects.

  That is, the mobile terminal control method according to the present invention is a mobile terminal control method for controlling a mobile terminal that performs wireless communication complying with IPv4 via a wireless LAN system, and there is a change in BSS due to handover of the own terminal. When the BSS change is detected by the detection step and the detection step, the subnet information is inquired to the DHCP server while continuing to transmit and receive data, and the subnet found by the inquiry is different from that before the BSS change. In the case of a subnet, a control step of obtaining a new IP address from a DHCP server and performing connection to the Internet using the IP address is provided.

  By the way, a combination of a plurality of BSSs is called an ESS (Extended Service Set). The above considers only the case where the BSS is changed by the handover, but in particular, when the handover is performed so that the ESS is changed, the subnet is also different, so the above problem may occur. it was high.

  In order to deal with the problem, in the mobile terminal of the present invention, the detecting means further detects that the ESS has changed when the own terminal has performed handover, and the control means detects the ESS by the detecting means. When the change is detected, the data communication is disconnected, the subnet information is inquired to the DHCP server, and if the subnet found by the inquiry is a different subnet from that before the ESS change, a new IP address is obtained from the DHCP server. It is desirable that the control for connecting to the Internet with the IP address is further performed.

  The mobile terminal according to the present invention also detects that the ESS has changed when the own terminal has performed a handover. When the detection is made, the control means disconnects the data communication, inquires about the subnet information to the DHCP server, and when the subnet found by the inquiry is a different subnet from that before the change of the ESS, a new IP address is obtained from the DHCP server. It also controls to acquire an address and connect to the Internet using the IP address.

  As a result, the mobile terminal according to the present invention can further shorten a series of processing time at the time of handover even when the ESS is changed by handover, and automatically obtains a new IP address and connects to the Internet. It can be performed.

  As described above, according to the present invention, when the BSS is changed by handover, the mobile terminal can continue to connect to the Internet without interrupting data transmission / reception as usual when the subnet is the same, and Even if the subnet is different, the series of processing time at the time of handover can be shortened without interrupting data transmission / reception, and a new IP address is automatically acquired to connect to the Internet. be able to.

  Hereinafter, an embodiment of a mobile terminal according to the present invention will be described with reference to the drawings.

  FIG. 1 is an overall configuration diagram of a wireless LAN system and a wireless communication system compliant with IPv4 in the present embodiment. As shown in the figure, the wireless communication system compliant with the wireless LAN system and IPv4 includes a mobile terminal 10, a wireless LAN access point 20 (generic name for 20A to 20D) that performs wireless communication with the mobile terminal 10, and the access point. BSS 30 (generic name of 30A-30D) for every 20th, ESS31 (generic name of 31A, 31B) that combines the plurality of BSS30, subnet 40 (generic name of 40A-40C), and router 50 that manages each subnet 40 ( And a DHCP server 60 that sets an IP address for the mobile terminal 10. The mobile terminal 10 corresponds to, for example, an IP wireless phone, a PDA (Personal Digital Assistants), a notebook computer, or the like. The subnet 40 is configured by one or a plurality of BSSs 30. For example, the subnet 40A includes BSS 30A and BSS 30B, the subnet 40B includes BSS 30C, and the subnet 40C includes BSS 30D.

  FIG. 2 is a configuration diagram of the mobile terminal 10. As shown in the figure, when the mobile terminal 10 performs handover, the wireless communication unit 12 that performs wireless communication with the access point 20, the Internet communication unit 14 that performs Internet communication through the wireless communication unit 12, and the mobile terminal 10 perform handover. 1 includes a detection unit 16 that detects a change in one BSS 30 and an ESS 31, and a control unit 18 that controls the Internet communication unit 14. The Internet 70 is a connection target of the mobile terminal 10. The detection of the change in the BSS 30 by the detection unit 16 is performed, for example, by detecting a change due to handover of the BSSID that is the identifier of the BSS 30 recognized by the wireless communication unit 12. The detection unit 16 detects the change in the ESS 31 by, for example, detecting a change due to handover of the ESSID that is the identifier of the ESS 31 recognized by the wireless communication unit 12.

  The mobile terminal 10 can communicate with the access point 20 and can connect to the Internet 70 by setting an IP address from the DHCP server 60 of FIG. 1 via the router 50 of FIG.

  Hereinafter, the process performed by the mobile terminal 10 of this embodiment is demonstrated using the flowchart of FIG.

  First, in the mobile terminal 10 in which wireless communication with the wireless LAN system and Internet connection are established, when the wireless communication unit 12 performs the handover process, the detection unit 16 detects that the BSS 30 has been changed due to the handover ( S01). For example, when the user of the mobile terminal 10 moves from the BSS 30A area to the BSS 30B area, the radio communication unit 12 performs a handover process, and the detection unit 16 detects a change from the BSS 30A to the BSS 30B.

  Subsequently, the detection unit 16 detects whether or not the ESS 31 has been changed due to the handover (S02).

  When the change of the ESS 31 is not detected, the control unit 18 controls the Internet communication unit 14 to inquire subnet information to the DHCP server 60 while continuing to transmit and receive data (S03). Here, the “subnet information” inquired to the DHCP server 60 corresponds to an IP address, a subnet mask, and the like proposed by the DHCP server 60. The above inquiry is made by transmitting DHCP Discover to the DHCP server 60.

  Subsequently, the control unit 18 compares the subnet information sent from the DHCP server 60 with the subnet information before the handover in response to the subnet information inquiry, and determines whether the subnet 40 is different before and after the handover ( S04). The subnet information of the inquiry result is included in the DHCP Offer transmitted from the DHCP server 60.

  If the subnet 40 is different before and after the handover in S04, the control unit 18 acquires a new IP address from the DHCP server 60, connects to the Internet with the new IP address, and resumes data communication. 14 is controlled. (S05, S06). For example, when the change of the BSS 30 is a change from the BSS 30B to the BSS 30C, the change is made from the subnet 40A to the subnet 40B, and thus the above processing is performed. The acquisition of the IP address is performed by transmitting a DHCP Request to the DHCP server 60 and receiving a DHCP ACK transmitted from the DHCP server 60.

  If the subnet 40 is the same before and after the handover in S04, Internet connection and data communication continue (S07). For example, in the case of a change from the BSS 30A to the BSS 30B, since the subnet 40A remains, the Internet connection and data communication are continued as described above.

  When the change of the ESS 31 is detected at the time of handover (S02), the control unit 18 controls the Internet communication unit 14 to disconnect the data communication and inquire the DHCP server 60 for subnet information (S08, S09).

  Subsequently, the control unit 18 compares the subnet information sent from the DHCP server 60 with the subnet information before the handover in response to the subnet information inquiry, and determines whether or not the subnet 40 is different before and after the handover (S10). ).

  If the subnet 40 is different before and after the handover at this time, the control unit 18 acquires a new IP address from the DHCP server 60, connects to the Internet 70 with the new IP address, and resumes data communication. 14 is controlled. (S11, S12). For example, when the change is from ESS 31A (BSS 20C) to ESS 31B (BSS 30D), the change is made from subnet 40B to subnet 40C, and thus the above processing is performed.

  If the subnet 40 is the same before and after the handover in S10, the control unit 18 controls the Internet communication unit 14 to connect to the Internet 70 using the IP address before the handover and resume data communication (S13).

  Thereby, when the BSS 30 is changed by the handover, the mobile terminal 10 in the present embodiment can continue the connection to the Internet 70 without interrupting data transmission / reception as usual when the subnet 40 is the same. Even when 40 becomes different, a series of processing time at the time of handover can be shortened without interrupting data transmission / reception, and a new IP address is automatically acquired and connected to the Internet 70. be able to.

  In addition, even when the ESS 31 is changed due to a handover, the mobile terminal 10 according to the present embodiment can further shorten a series of processing times at the time of handover, automatically acquire a new IP address, and connect to the Internet 70. Connection can be made.

1 is an overall configuration diagram of a wireless communication system compliant with a wireless LAN system and IPv4 in an embodiment of the present invention. It is a block diagram of a mobile terminal. It is a flowchart showing the process in embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Mobile terminal, 12 ... Wireless communication part, 14 ... Internet communication part, 16 ... Detection part, 18 ... Control part, 20 ... Access point, 30, 30A, 30B, 30C, 30D ... BSS, 31, 31A, 31B ... ESS, 40, 40A, 40B, 40C ... subnet, 50, 50A, 50B, 50C ... router, 60 ... DHCP server, 70 ... Internet.

Claims (3)

A mobile terminal that performs wireless communication based on IPv4 via a wireless LAN system,
Detecting means for detecting that the BSS has been changed due to handover of the own terminal;
When a change in the BSS is detected by the detecting means, the DHCP server is inquired for subnet information while continuing to transmit and receive data. And a control means for controlling to obtain a new IP address from the Internet and to connect to the Internet using the IP address. The detection means further detects that the ESS has changed when the terminal has performed handover,
When the control unit detects a change in ESS by the detection unit, the control unit disconnects data communication, inquires about the subnet information to the DHCP server, and the subnet determined by the inquiry is a different subnet from that before the change of the ESS. 2. The mobile terminal according to claim 1, further comprising a control of acquiring a new IP address from a DHCP server and connecting to the Internet using the IP address. A mobile terminal control method for controlling a mobile terminal performing wireless communication based on IPv4 via a wireless LAN system,
A detection step of detecting that the BSS has changed due to handover of the own terminal;
When a change in the BSS is detected by the detection step, the DHCP server is inquired of the subnet information while continuing to transmit and receive data. And a control step of performing control to obtain a new IP address from the Internet and connect to the Internet using the IP address.

Images