JP2009206803A - Radio terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio terminal which can continue a communication in a state that a counterpart is specified when a cellular communication is switched to an ad hoc communication, and can prevent a reduction in communication performance due to a useless connection with the other terminals. <P>SOLUTION: A cellular communication part 11 sends a BSSID generated at a BSSID generating part 13 at start of communication to the other radio terminals via a base station of an infra-network, and an ad hoc communication part 12 receives a probe request during communication execution by the infra-network. When a control part 23 determines that the identical BSSID to the BSSID stored in an ad hoc information storing part 14 is included in the probe request concerned, the ad hoc communication part 12 is ad-hoc-connected to the radio terminal of a source of the probe request concerned, and the control part 23 switches a communication path from the cellular communication part 11 to the ad hoc communication part 12. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a wireless terminal that has two communication functions, a cellular communication function and an ad hoc communication function, and can perform handoff between different wireless communication systems.

  Conventionally, as a technique for performing inter-system handoff between different wireless communication systems, a technique for switching a communication method from CDMA (Code Division Multiple Access) communication to wireless LAN (Local Area Network) communication has been proposed. On the other hand, among communication methods using a wireless LAN, there is a communication method called ad hoc communication in which terminals directly communicate with each other without using an access point (AP). In this communication method, an SSID (Service) is used as a network identifier. Set IDentifier) and BSSID (Basic Service Set IDentifier) are used.

  As a communication method using a wireless LAN, for example, “wireless LAN communication method” (see Patent Document 1), “method and system for improving transmission efficiency of a wireless local area network” (see Patent Document 2), “Wireless LAN mode switching method and wireless LAN terminal” (see Patent Document 3) is known.

These “wireless LAN communication system”, “method and system for improving the transmission efficiency of a wireless local area network”, and “wireless LAN mode switching method and wireless LAN terminal” are one of communication systems using a wireless LAN. There has been proposed a technology for switching a communication method from infrastructure communication that performs communication via an AP to ad hoc communication that does not involve an AP.
JP 2004-128785 A JP 2004-254254 A JP 2005-333378 A

  However, when performing ad hoc communication, terminals using the same network identifier form the same network. For this reason, ad hoc communication cannot be performed between specific terminals, interference from other terminals and unnecessary communication increase, and it is inevitable that the communication performance deteriorates.

  As a countermeasure against such a situation, there is a method of notifying a specific terminal of the network identifier and limiting the partner terminal. However, since the network identifier used in ad hoc communication is included in the beacon information, In the method, since the third terminal other than the counterpart terminal can easily know the network identifier, it cannot be a means for limiting the communication counterpart. In addition, a method of performing encrypted communication between two terminals is also conceivable. However, when encryption processing is performed, it causes a decrease in communication speed or occurrence of delay, so that a TV phone, an IP (Internet Protocol) phone, And it is not preferable when performing one-to-one real-time communication such as a communication battle game.

  The situation described above also occurs when a terminal that is in cellular communication with another terminal switches from cellular communication to ad hoc communication. That is, when switching from cellular communication to ad hoc communication between terminals in which a specific SSID given by a service company or the like is registered in advance, there is already an ad hoc network using the same SSID in the same area. If this happens, you will be unintentionally connected to that network, and you will not be able to achieve the expected communication performance. Furthermore, since other terminals that have seen the information in the beacon can join the ad hoc network later, the communication performance may be deteriorated due to the influence of these terminals.

  “Wireless LAN communication method” (see Patent Document 1), “Method and system for improving transmission efficiency of wireless local area network” (see Patent Document 2), “Wireless LAN mode switching method and wireless LAN terminal” (Refer to Patent Document 3), a method for switching a communication method from infrastructure communication to ad hoc communication is proposed. However, in the “wireless LAN communication method” and “wireless LAN mode switching method and wireless LAN terminal”, a partner terminal is used. However, “Method and system for improving the transmission efficiency of a wireless local area network” limits the partner terminal by notifying the SSID, Since the SSID can be easily known by the third terminal, this method is also used to continue the communication specifying the partner terminal. Not suitable.

  An object of the present invention is to enable wireless communication capable of continuing communication in a state where a partner is specified when switching from cellular communication to ad hoc communication, and preventing deterioration in communication performance due to unnecessary connection with other terminals. To provide a terminal.

  In order to achieve the above object, a wireless terminal according to the present invention performs communication between an ad hoc communication unit that performs ad hoc communication with one or more other wireless terminals and another wireless terminal via a base station of an infrastructure network. An infrastructure network communication unit to perform, a BSSID generation unit that generates a BSSID used for the ad hoc communication, a storage unit that stores the BSSID generated by the BSSID generation unit, and the probe request received by the ad hoc communication unit A determination unit that determines whether or not the same BSSID as the BSSID stored in the unit is included, and a communication switching unit that switches a communication path of communication being executed in the infrastructure network communication unit to the ad hoc communication unit, The infrastructure network communication unit is generated by the BSSID generation unit at the start of communication The BSSID is transmitted to the other wireless terminal via the base station of the infrastructure network, and a probe request is received by the ad hoc communication unit during communication execution by the infrastructure network, and the probe request is received by the determination unit. Is determined to include the same BSSID as the BSSID stored in the storage unit, the ad hoc communication unit establishes an ad hoc connection with the wireless terminal that is the source of the probe request, and the communication switching unit The path is switched from the infrastructure network communication unit to the ad hoc communication unit.

  Moreover, in this invention, it further includes a location information acquisition unit that acquires its own location information, and the infrastructure network communication unit periodically transmits the location information acquired by the location information acquisition unit to the other wireless terminal. It is preferable.

  The wireless terminal according to the present invention includes an ad hoc communication unit that performs ad hoc communication with one or more other wireless terminals, and an infrastructure network communication unit that performs communication with other wireless terminals via an infrastructure network base station. A storage unit that stores the BSSID received by the infrastructure network communication unit, and a probe response received by the ad hoc communication unit includes a BSSID that is the same as the BSSID stored in the storage unit And a communication switching unit for switching a communication path of communication being executed in the infrastructure network communication unit to the ad hoc communication unit, wherein the ad hoc communication unit is configured to store the storage unit during communication execution by the infrastructure network. The probe request including the BSSID stored in the When it is determined that the same BSSID as the BSSID stored in the storage unit is included in the probe response received by the ad hoc communication unit, the ad hoc communication unit makes an ad hoc connection with the wireless terminal that is the source of the probe response. The communication switching unit switches the communication path from the infrastructure network communication unit to the ad hoc communication unit.

  Further, in the present invention, it further includes a position information acquisition unit that acquires its own position information, and the ad hoc communication unit includes the position information of the other wireless terminal periodically received by the infrastructure network communication unit, It is preferable that transmission of the probe request is started based on a comparison result with position information periodically acquired by the position information acquisition unit.

  According to the present invention, when switching from cellular communication to ad hoc communication, by specifying BSSID in addition to SSID as a network identifier, communication can be continued in a state where the other party is specified, and wasteful connection with other terminals It is possible to prevent a decrease in communication performance due to performing.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a circuit configuration of a wireless terminal according to an embodiment of the present invention. As shown in FIG. 1, the wireless terminal 10 includes a cellular communication unit (infrastructure network communication unit) 11, an ad hoc communication unit 12, a BSSID generation unit 13, an ad hoc information storage unit (storage unit) 14, and a location information acquisition unit. 15, position information transmission / reception unit 16, position information determination unit 17, ad hoc availability response transmission / reception unit 18, input unit 19, display unit 20, timer unit 21, interrupt setting unit 22, and control unit 23.

  The cellular communication unit 11 performs communication with other wireless terminals via the base station of the infrastructure network, and the ad hoc communication unit 12 performs ad hoc communication with one or more other wireless terminals. The BSSID generation unit 13 generates a BSSID used for ad hoc communication, and the ad hoc information storage unit 14 receives information necessary for ad hoc communication, for example, the SSID, the BSSID generated by the BSSID generation unit 13, or the cellular communication unit 11. BSSID is stored. The position information acquisition unit 15 acquires position information related to the current position of the terminal using GPS and base station information, specifies the current position of the terminal based on the acquired position information, and the position information transmission / reception unit 16 Transmit / receive position information.

  The position information determination unit 17 determines whether the distance between both terminals is close based on the position information of the own terminal and the received position information of the other terminal, and the ad hoc availability response transmission / reception unit 18 determines the position information determination unit 17. Transmit / receive determination information indicating whether or not the ad hoc communication determined in step 1 is possible. The input unit 19 performs processing of various information input via information input means such as various operation keys, for example, and the display unit 20 displays video, subtitles, etc. based on video data, subtitle data, etc., for example, a liquid crystal display Displayed on the display screen. The timer unit 21 sets a timer value, and the interrupt setting unit 22 sets whether to allow a third party to join (interrupt) an ad hoc network.

  The control unit 23 determines whether the probe request (Probe Request) or the probe response (Probe Response) received by the ad hoc communication unit 12 includes the same BSSID as the BSSID stored in the ad hoc information storage unit 14. And a communication switching unit that switches a communication path of communication being executed in the cellular communication unit (infrastructure network communication unit) 11 to the ad hoc communication unit 12. Furthermore, by executing a control program or the like, the operation of each of the above parts is controlled to realize various functional elements.

  In the wireless terminal 10 having the above configuration, the cellular communication unit 11 transmits the BSSID generated by the BSSID generation unit 13 at the start of communication to another wireless terminal via the base station of the infrastructure network. The ad hoc communication unit 12 receives a probe request during communication execution through the infrastructure network, and the determination unit (control unit 23) includes the same BSSID as the BSSID stored in the ad hoc information storage unit 14 in the probe request. Is determined, the ad hoc connection is established with the wireless terminal that has transmitted the probe request. The communication switching unit (control unit 23) switches the communication path from the cellular communication unit 11 to the ad hoc communication unit 12. Further, the cellular communication unit 11 periodically transmits the position information acquired by the position information acquisition unit 15 to other wireless terminals.

  Moreover, the ad hoc communication part 12 transmits the probe request containing BSSID memorize | stored in the ad hoc information storage part 14 during communication execution by an infrastructure network. In addition, the ad hoc communication unit 12 is determined by the determination unit (control unit 23) that the probe response received by the ad hoc communication unit 12 includes the same BSSID as the BSSID stored in the ad hoc information storage unit 14. In this case, an ad hoc connection is established with the wireless terminal that is the transmission source of the probe response. The communication switching unit (control unit 23) switches the communication path from the cellular communication unit 11 to the ad hoc communication unit 12. Furthermore, the ad hoc communication unit 12 determines whether the probe information is based on the comparison result between the position information of other wireless terminals periodically received by the cellular communication unit 11 and the position information periodically acquired by the position information acquisition unit 15. Start sending requests.

As described above, the wireless terminal 10 having the two communication functions of the cellular communication function and the ad hoc communication function transmits and receives the position information, and the own terminal based on the position information of the own terminal and the received position information of the partner terminal. And the other terminal are determined whether or not the distance is close, and based on the determination result, determination information as to whether ad hoc communication is possible is transmitted and received.
And when the wireless terminal 10 constructs an ad hoc network with a terminal in cellular communication, it establishes an ad hoc connection only with a specific terminal by using a pre-registered SSID and BSSID, and continues communication. Seamlessly switch from cellular to ad hoc communications.

  The BSSID specified when constructing an ad hoc network is registered in the terminal at the start of cellular communication, and can be updated regularly or irregularly during ad hoc communication. . Also, when a probe request is received that specifies the same SSID as the SSID registered in the terminal from another terminal during ad hoc communication, but a BSSID different from the BSSID registered in the terminal. In addition, it is possible not to return a probe response.

  The wireless terminal 10 uses the location information of both terminals in the cellular communication, and when it can be determined that the partner terminal in the cellular communication is close to its own terminal, the wireless terminal 10 tries an ad hoc connection, and gives a user instruction. If the cellular communication connection with the partner terminal is disconnected due to the cause, the ad hoc connection is attempted. Further, during cellular communication, the location information of its own terminal is notified to the other terminal (other terminals) at regular intervals.

  When receiving the location information from the counterpart terminal during cellular communication, the radio terminal 10 compares it with the location information of its own terminal, and if it can be determined that the counterpart terminal is nearby, sends an ad hoc response to the counterpart terminal. If it cannot be determined that it is present, an ad hoc impossible response is transmitted to the partner terminal. Then, after transmitting an ad hoc response, a probe that starts transmitting a beacon that specifies a pre-registered SSID and a BSSID registered at the start of communication, and that specifies the same SSID and BSSID registered at the start of communication from the other terminal during beacon transmission When a request is received, a probe response is transmitted to the partner terminal, and an ad hoc connection is established.

  When the wireless terminal 10 receives an ad hoc response from the partner terminal, the wireless terminal 10 transmits a probe request specifying the pre-registered SSID and the BSSID registered at the start of communication to the partner terminal and receives a probe response from the partner terminal. Establish a connection. After the ad hoc connection is established, the cellular communication connection is disconnected, the communication path is switched to the ad hoc communication system, and ad hoc communication is started. At this time, the IP address used for the ad-hoc communication is used as it is during the cellular communication.

The wireless terminal 10 continues the cellular communication when receiving a non-ad hoc response from the counterpart terminal, and continues the cellular communication when the probe request or the probe response cannot be received from the counterpart terminal during the cellular communication.
FIG. 2 is an explanatory diagram conceptually showing a state during cellular communication by the terminal. FIG. 3 is an explanatory diagram conceptually showing a state after moving to an ad hoc communication possible area during cellular communication by a terminal. FIG. 4 is an explanatory diagram conceptually showing a state during ad hoc communication by the terminal.

  As shown in FIG. 2, the wireless terminal (own terminal) 10 is in cellular communication with the counterpart terminal 24 via the AP, and at the same time, the ad hoc network A (SSID: common, BSSID) with the other terminals 25a to 25d. 12: 34: 56: 78: 90: 0a, channel: 1ch). Here, when the wireless terminal 10 wants to continue the call only with the other party terminal 24 during the call, that is, when the one-to-one real-time communication with the other party terminal 24 such as a TV phone, an IP phone, or a communication game is performed. The counterpart terminal 24 moves to a range where the ad hoc network A can be constructed (ad hoc communication possible area).

  As shown in FIG. 3, the wireless terminal 10 is in cellular communication with the partner terminal 24 even after the partner terminal 24 moves to the ad hoc communicable area, but does not perform unnecessary communication with other terminals that are not desired. In order to suppress interference from other terminals, an ad hoc network different from the ad hoc network A is constructed. At this time, an ad hoc network different from the ad hoc network A can be constructed by using a BSSID different from the BSSID that is the identifier of the ad hoc network A.

  As shown in FIG. 4, the wireless terminal 10 has an ad hoc network B (SSID: common, BSSID: ab: cd: ef: 01: 23: 45, channel: 10ch) is established and ad hoc communication is performed with the counterpart terminal 24. Here, the update of the BSSID will be described.

  FIG. 5 is a conceptual explanatory diagram showing BSSID update processing. As shown in FIG. 5, the terminal periodically transmits beacon information, but BSSID update timing is taken in accordance with this beacon interval. The beacon information includes a MAC (Media Access Control) frame (MAC Frame) and a management frame (Management Frame). The MAC frame includes a current BSSID (Current BSSID: ab: cd: ef: 01: 23: 45), and the management frame includes a time stamp (Timestamp: 0 × 000000003 e26f4c2).

  Based on these current BSSIDs (Current BSSID: ab: cd: ef: 01: 23: 45) and time stamp (Timestamp: 0 × 000000003 e26f4c2) values, a seed is formed, and a hash function (for example, RCBS algorithm) to form a new BSSID (New BSSID: 1a: 2b: 3c: 4d: 5e: 6f).

Next, a specific example of handoff processing from cellular communication to ad hoc communication by the wireless terminal 10 according to the present invention will be described.
(Master terminal basic operation)
Here, a case where IP communication is performed will be described. The terminal that first sent a connection establishment request (SYN) for IP connection, that is, the terminal that started communication is the master terminal, and the terminal that returned the request and response (ACK + SYN) is the slave terminal. To do.

  6 is a flowchart (part 1) showing a flow of basic operation of a master terminal in a handoff process from cellular communication to ad hoc communication by the wireless terminal in FIG. 1, and FIG. 7 is a flowchart from cellular communication to ad hoc by the wireless terminal in FIG. It is a flowchart (the 2) which shows the flow of a master terminal basic operation | movement in the handoff process to communication.

  As shown in FIGS. 6 and 7, first, the master terminal completes establishment of communication connection by TCP (Transmission Control Protocol) when cellular communication with the slave terminal is started (step S101). When the communication connection is established, the master terminal generates a BSSID based on the MAC address of the own terminal, registers the BSSID in the own terminal, and transmits the BSSID to the slave terminal after registration (step S102). Thereby, cellular communication is started between the master terminal and the slave terminal (step S103). At the same time that cellular communication is established between the master terminal and the slave terminal, the master terminal activates a communication position information notification timer (step S104).

Next, loop processing is started under the condition that cellular communication is being performed (step S105), and it is determined whether or not the position information notification timer has expired (step S106). If the position information notification timer does not expire as a result of the determination (No), the determination is repeated. On the other hand, if the position information notification timer expires (Yes), the master terminal transmits the position information of the own terminal to the slave terminal ( Step S107).
After the location information is transmitted by the master terminal, it is determined whether or not the master terminal has received a response from the slave terminal (step S108). As a result of the determination, if the master terminal has not received a response from the slave terminal (No), the process returns to step S107 to transmit the position information of the own terminal to the slave terminal.

  As a result of the determination in step S108, if the master terminal receives a response from the slave terminal (Yes), and if the received response is an ad hoc possible response, the master terminal maintains the cellular communication and sends the SSID to the slave terminal. A probe request is transmitted using the BSSID registered in advance (step S109). The SSID used at this time is given in advance by a service company or the like, and is registered in the wireless terminal.

  After transmitting the probe request to the slave terminal, it is determined whether or not the master terminal has received a probe response from the slave terminal (step S110). As a result of the determination, when the master terminal receives the probe response (Yes), the master terminal determines whether or not a BSSID registered in advance and a registered SSID are specified (step S111). As a result of the determination, if it is not specified (No), the process returns to Step S110 and repeats the determination. On the other hand, if specified (Yes), the master terminal establishes an ad hoc connection with the slave terminal, and the cellular terminal The communication is disconnected (step S112).

  As a result of the determination in step S108, if the master terminal has received an ad hoc non-response, and if the master terminal has not received a probe response as a result of determination in step S110 (No), the master terminal is a slave terminal Cellular communication will continue.

  As a result of the determination in step S108, if the master terminal has received a response from the slave terminal (Yes), it is determined that the received ad hoc response is not possible, and in step S110 that the master terminal cannot receive a probe response. Then, it is determined whether or not the master terminal has received position information from the slave terminal (step S113). As a result of the determination, if the master terminal has not received the position information from the slave terminal (No), the determination is repeated. On the other hand, if the master terminal has received the position information from the slave terminal (Yes), the master terminal It is determined whether or not the position of the slave terminal is close to the position of the slave terminal (step S114).

  If the result of determination in step S114 is that the own terminal and the slave terminal are close (Yes), the master terminal transmits an ad hoc possible response to the slave terminal (step S115), while the self terminal and the slave terminal are not close (No). In this case, the master terminal transmits an ad hoc impossible response to the slave terminal (step S116).

  After the master terminal transmits an ad hoc response to the slave terminal, the master terminal designates the BSSID registered in advance and the SSID registered in advance, and starts beacon transmission (step S117). After the start of beacon transmission, it is determined whether or not the master terminal has received a probe response from the slave terminal (step S118). As a result of the determination, when the master terminal receives the probe response (Yes), the master terminal determines whether or not a previously registered BSSID and a registered SSID are specified (step S119), while the master terminal If no probe response is received (No), the master terminal stops transmitting beacons (step S120).

  If the result of determination in step S119 is not specified (No), the process returns to step S118 to repeat the determination. On the other hand, if specified (Yes), the same BSSID and SSID are specified from the slave terminal. When receiving the probe request, the master terminal transmits a probe response to the slave terminal (step S121). After transmitting the probe response, the master terminal establishes an ad hoc connection with the slave terminal (step S122).

  After the master terminal transmits an ad hoc impossible response to the slave terminal in step S116, and after the master terminal stops transmitting beacons in step S120, the location information notification timer is started to continue cellular communication (step S120). S123), loop processing is repeated.

In step S112 and step S122, after the master terminal establishes an ad hoc connection with the slave terminal, the communication path is switched to the ad hoc communication system (step S124). When switching to the ad hoc communication system, both the master terminal and the slave terminal continue to use the IP addresses used during the cellular communication. And ad hoc communication is started and cellular communication is cut | disconnected (step S125).
Thereafter, the master terminal basic operation processing is terminated.

Here, the means for acquiring the position information is not limited, but examples include a method using GPS and a method of specifying an approximate position based on information of Active Set.
(Slave terminal basic operation)
Here, a case where IP communication is performed will be described. The slave terminal establishes an IP connection during cellular communication with the master terminal. At this time, when the slave terminal receives the BSSID notified from the master terminal, the slave terminal registers the BSSID in the wireless terminal. The subsequent operation is the same as the basic operation of the master terminal except that the position information is first received from the master terminal.

FIG. 8 is a flowchart (part 1) illustrating a flow of basic operation of a slave terminal in a handoff process from cellular communication to ad hoc communication by the wireless terminal in FIG. 1, and FIG. 9 is a flowchart from cellular communication to ad hoc by the wireless terminal in FIG. It is a flowchart (the 2) which shows the flow of a slave terminal basic operation | movement in the handoff process for communication.
As shown in FIGS. 8 and 9, first, the slave terminal completes establishment of communication connection by TCP when cellular communication with the master terminal is started (step S201). When the communication connection is established, the slave terminal receives and registers the BSSID transmitted from the master terminal (step S202). Thereby, cellular communication is started between the slave terminal and the master terminal (step S203).

  Next, loop processing is started under the condition that cellular communication is being performed (step S204), and it is determined whether or not the slave terminal has received location information from the master terminal (step S205). As a result of the determination, if the slave terminal has not received the position information from the master terminal (No), the determination is repeated. On the other hand, if the slave terminal has received the position information from the master terminal (Yes), the slave terminal It is determined whether or not the position of the master terminal and the position of the master terminal are close (step S206).

  If the result of determination in step S206 is that the terminal is not close to the master terminal (No), the slave terminal sends an ad hoc incapable response to the master terminal (step S207), while the terminal is close to the master terminal (Yes). In this case, the slave terminal transmits an ad hoc response to the master terminal (step S208).

  After transmitting the ad hoc possible response to the master terminal, the slave terminal designates the BSSID registered in advance and the registered SSID, and starts transmitting a beacon (step S209). After the start of beacon transmission, it is determined whether the slave terminal has received a probe request (step S210). If the result of determination is that no probe request has been received (No), the slave terminal stops transmitting beacons. (Step S211) When the probe request is received (Yes), the slave terminal determines whether or not a previously registered BSSID and a registered SSID are specified (Step S212).

  As a result of the determination in step S212, if the BSSID registered in advance and the registered SSID are not specified in the probe request (No), the process returns to step S210 and repeats the determination. On the other hand, if specified (Yes), That is, when receiving a probe request in which the same BSSID and SSID are specified from the master terminal, the slave terminal transmits a probe response to the master terminal (step S213). After transmitting the probe response, the slave terminal establishes an ad hoc connection with the master terminal (step S214).

  In step S207, after the slave terminal transmits an ad hoc incapable response to the master terminal, and in step S211, after the slave terminal stops transmitting beacons, the slave terminal starts a position information notification timer (step S215). . After starting the position information notification timer, it is determined whether or not the position information notification timer has expired (step S216). If the position information notification timer has not expired (No), the determination is repeated, while the position information notification timer Is completed (Yes), the slave terminal transmits the position information of the own terminal to the master terminal (step S217).

After the position information is transmitted by the slave terminal, it is determined whether the slave terminal has received a response from the master terminal (step S218). As a result of the determination, if the slave terminal has not received a response from the master terminal (No), the process returns to step S217 to transmit the position information of the own terminal to the master terminal.
As a result of the determination in step S218, if the slave terminal has received a response from the master terminal (Yes), and if the received response is an ad hoc response, the slave terminal maintains the cellular communication and sends the SSID to the master terminal. A probe request is transmitted using the BSSID registered in advance (step S219). The SSID used at this time is given in advance by a service company or the like, and is registered in the wireless terminal.

  After transmitting a probe request to the master terminal, it is determined whether the slave terminal has received a probe response from the master terminal (step S220). As a result of the determination, when the slave terminal receives the probe response (Yes), the slave terminal determines whether the BSSID registered in advance and the registered SSID are specified (step S221). As a result of the determination, when the BSSID registered in advance and the registered SSID are not specified in the probe response (No), the process returns to Step S220 and repeats the determination. On the other hand, if specified (Yes), the slave terminal Then, an ad hoc connection is established with the master terminal (step S222).

  As a result of the determination in step S218, when the slave terminal has received a response from the master terminal (Yes), if the received response is an ad hoc incapable response, the slave terminal cannot receive a probe response in step S220 (No). Then, the cellular communication is continued and the loop process is repeated.

In step S214 and step S222, after the slave terminal establishes an ad hoc connection with the master terminal, the communication path is switched to the ad hoc communication system (step S223). When switching to the ad hoc communication system, both the slave terminal and the master terminal continue to use the IP addresses used during the cellular communication. And ad hoc communication is started and cellular communication is cut | disconnected (step S224).
Here, as an example, the method of periodically exchanging location information has been described. However, this is not the only reason why an ad hoc connection is attempted. For example, a message prompting an ad hoc search (standby) is sent between a master terminal and a slave terminal. You may communicate regularly.

(Operation when master terminal is disconnected)
FIG. 10 is a flowchart showing a flow of an operation when the master terminal is disconnected in the handoff process from the cellular communication to the ad hoc communication by the wireless terminal of FIG. As shown in FIG. 10, first, loop processing is started with the cellular communication being performed as a loop condition (step S301), and it is determined whether there is a communication disconnection event (step S302). In other words, it is determined whether or not the connection by the cellular communication between the master terminal and the slave terminal has been disconnected due to the removal of the instruction from the user during the cellular communication (for example, out-of-service transition or network failure). To do.

  If the result of determination in step S302 is that there is a communication disconnection event (Yes), the master terminal starts transmitting beacons by specifying the BSSID and SSID registered in advance (step S303), while there is no communication disconnection event. If (No), the master terminal repeats the loop processing. The SSID used at this time is given by a service company or the like and is registered in advance.

  After starting the transmission of the beacon, it is determined whether or not the master terminal has received a probe request from the slave terminal (step S304). As a result of the determination, when the probe request is received from the slave terminal (Yes), the master terminal determines whether the received probe request specifies the BSSID registered in advance and the registered SSID (step S305). ).

  If the BSSID registered in advance and the registered SSID are not specified in the probe request in the determination in step S305 (No), the process returns to step S304 to repeat the determination, while if specified (Yes), that is, When receiving the probe request in which the same BSSID and SSID are designated from the slave terminal, the master terminal transmits a probe response to the slave terminal (step S306). After transmitting the probe response, the master terminal establishes an ad hoc connection with the slave terminal (step S307). Thereafter, the master terminal and the slave terminal start ad hoc communication and disconnect cellular communication (step S308). Thereafter, the processing of the operation when the master terminal is disconnected is terminated.

On the other hand, if the result of determination in step S304 is that a probe request could not be received from the slave terminal (No), the master terminal stops transmitting beacons (step S309). In this case, ad hoc communication could not be connected between the master terminal and the slave terminal. Thereafter, the processing of the operation when the master terminal is disconnected is terminated.
(Operation when slave terminal is disconnected)
FIG. 11 is a flowchart showing a flow of operation when the slave terminal is disconnected in the handoff process from the cellular communication to the ad hoc communication by the wireless terminal of FIG. As shown in FIG. 11, first, loop processing is started with the cellular communication being performed as a loop condition (step S401), and it is determined whether there is a communication disconnection event (step S402).

In other words, it is determined whether or not the connection by the cellular communication between the slave terminal and the master terminal is disconnected due to the removal of the instruction from the user during the cellular communication (for example, out-of-service transition or network failure). To do.
As a result of the determination in step S402, if there is a communication disconnection event (Yes), the slave terminal starts transmitting a probe request by specifying the BSSID and SSID registered in advance (step S403). If not (No), the master terminal repeats the loop processing. The SSID used at this time is given by a service company or the like and is registered in advance.

  After starting the transmission of the probe request, it is determined whether or not the slave terminal has received a probe response from the master terminal (step S404). When the probe response is received from the master terminal as a result of the determination (Yes), the slave terminal determines whether the received probe response specifies a BSSID registered in advance and a registered SSID (step S405). ).

  When the BSSID registered in advance and the registered SSID are not specified in the probe response in the determination in step S405 (No), the process returns to step S404 and the determination is repeated. On the other hand, if it is specified (Yes), that is, When receiving the probe response in which the same BSSID and SSID are specified from the master terminal, the slave terminal establishes an ad hoc connection with the master terminal (step S406). Thereafter, the slave terminal and the master terminal start ad hoc communication and disconnect cellular communication (step S407). Thereafter, the processing of the operation when the slave terminal is disconnected ends.

  On the other hand, as a result of the determination in step S404, if the probe response cannot be received from the master terminal (No), the slave terminal ends the operation of the slave terminal disconnection operation.

(Operation during ad hoc communication 1)
FIG. 12 is a flowchart showing a flow of operation 1 during ad hoc communication by the wireless terminal of FIG. As shown in FIG. 12, first, loop processing is started with ad hoc communication being performed as a loop condition (step S501), and both terminals in ad hoc communication determine whether or not it is the BSSID update timing (step S502).

As a result of the determination, if it is the BSSID update timing (Yes), the BSSID currently in use is registered in the terminal (step S503). On the other hand, if it is not the BSSID update timing (No), the loop process is repeated.
That is, both terminals in ad hoc communication register the BSSID currently in use in the terminal at every BSSID update timing. The update timing of the BSSID is a fixed time (for example, about 5 to 10 seconds after the start of ad hoc communication), but may be irregular. As a method of updating irregularly, a value distributed over a range of about 5 to 10 seconds calculated from the time stamp value of the previous beacon and the hash function (the same is used in both terminals) is used as the update time. A method is mentioned. In this case, the time until the next update is calculated when the BSSID is updated.

Also, it is assumed that BSSIDs are registered twice or more in the terminal in the past. Thereby, when the BSSID update timing comes after sending the probe request, it is possible to prevent the BSSID of the probe response from being different.
Next, both terminals in ad hoc communication register a BSSID in the terminal, and then generate a new BSSID from the current BSSID and the time stamp value of the immediately preceding beacon (step S504). The new BSSID (New BSSID) is encrypted and generated by, for example, the RC4 algorithm based on the Seed generated from the current BSSID (Current BSSID) and the time stamp value of the immediately preceding beacon (see FIG. 5).

  After generating a new BSSID, both terminals in ad hoc communication continue ad hoc communication using the generated new BSSID (step S505).

(Operation during ad hoc communication 2)
FIG. 13 is a flowchart showing a flow of operation 2 during ad hoc communication by the wireless terminal of FIG. As shown in FIG. 13, first, loop processing is started under the condition of ad hoc communication as a loop condition (step S601), and the terminal in ad hoc communication receives a probe request (SSID is registered common information) from another terminal. It is determined whether or not (step S602).

  If the result of determination in step S602 is that the terminal in ad hoc communication has received a probe request (Yes), it is determined whether or not the BSSID of the probe request is unspecified (step S603), and as a result of determination in step S603, the BSSID is If it is not unspecified (No), it is determined whether the BSSID is currently in use or registered in the terminal (step S604).

  If the result of determination in step S604 is that the BSSID is currently in use or registered in the terminal (Yes), the terminal in ad hoc communication transmits a probe response specifying the BSSID currently in use (Step S605). After transmitting the probe response, it is determined whether the terminal in ad hoc communication has received a probe response from another terminal (step S606).

  On the other hand, if the result of determination in step S602 is that the terminal in ad hoc communication does not receive a probe request (No), or if the result of determination in step S603 is that BSSID is unspecified (Yes), or in step S604 As a result of the determination, if the BSSID is not currently used or registered in the terminal (No), it is determined whether the terminal in ad hoc communication has received a probe response from another terminal ( Step S606).

  Next, if the result of determination in step S606 is that the terminal in ad hoc communication has received a probe response (Yes), it is determined whether the BSSID is currently in use or registered in the terminal (step S606). S607). If the result of determination in step S607 is that the BSSID is currently in use or registered in the terminal (Yes), the ad hoc communication terminal specifies the currently used BSSID and continues ad hoc communication. (Step S608), the loop process is repeated.

On the other hand, if the result of determination in step S606 is that the terminal in ad hoc communication does not receive a probe response (No), or the result of determination in step S607 is that the BSSID is currently in use or registered in the terminal If not (No), the loop process is repeated.
That is, when a probe request having the same SSID is received from another terminal during ad hoc communication, the received terminal checks the value of the BSSID. If the BSSID is not specified (all F) as a result of the check, the received terminal determines that the transmitted terminal is not the desired partner, and therefore does not return a probe response.

  On the other hand, if the BSSID is either currently used or the past registered in the terminal, the received terminal determines that the transmitted terminal is the desired partner, and the BSSID currently in use. Is designated and a probe response is transmitted (step S605). Here, not only the BSSID that is currently in use but also the past ones registered in the terminal are subject to judgment. After the partner terminal transmits the probe request, the own terminal receives the probe request. This is because the case where the BSSID is updated before the process is taken into consideration. If a BSSID other than the BSSID is specified, it is determined that the transmitted terminal is not a desired partner, and no probe response is returned.

  Also, when a probe response is received from another terminal during ad hoc communication, the received terminal checks the BSSID value. As a result of the check, if the BSSID is either currently used or past registered in the terminal, the received terminal determines that the transmitted terminal is a desired partner and is currently in use. Ad-hoc communication is continued using the BSSID. Here, not only the BSSID that is currently in use but also the past ones registered in the terminal are subject to judgment. After the partner terminal transmits the probe request, the own terminal receives the probe request. This is because the case where the BSSID is updated before the process is taken into consideration. If a BSSID other than the BSSID is specified, it is determined that the transmitting terminal is not a desired partner, and ad hoc communication is not performed.

  As described above, the process in the operation 1 during ad hoc communication (see FIG. 12) and the process in the operation 2 during ad hoc communication (see FIG. 13) are performed when other terminals are not allowed to join the ad hoc network later. However, it may be possible to permit the participation of other terminals. When setting is made so that the participation of other terminals can be permitted, updating of the BSSID may be stopped, and a probe response may be returned in response to a probe request with the same SSID and an unspecified BSSID.

  Note that in the operation 2 during ad hoc communication (see FIG. 13), the processing associated with reception of the probe request from step S602 to step S605 and the processing associated with reception of the probe response from step S606 to step S608 are interchanged. Also good. That is, the process associated with reception of the probe response from step S606 to step S608 may be performed first, and then the process associated with reception of the probe request from step S602 to step S605 may be performed.

As described above, when switching from cellular communication to ad hoc communication by the wireless terminal 10 according to the present invention, by specifying BSSID in addition to SSID as a network identifier, communication is continued in a state in which a partner terminal for communication is specified. Can do. For this reason, it is possible to prevent a decrease in communication performance due to useless connection with another terminal that is not the communication partner.
In addition, by periodically updating the BSSID that is a network identifier, it is possible to prevent other terminals that are not communicating counterpart terminals from easily joining the ad hoc network to which the terminal is connected. For this reason, it is possible to prevent performance degradation due to useless communication.

  In addition, by using BSSID as the network identifier that is periodically updated, ad hoc communication can be continued smoothly even after updating. On the other hand, when the SSID is used as the network identifier, the connection is interrupted each time it is updated. Therefore, ad hoc communication cannot be maintained. Therefore, by using a known SSID and registering a common BSSID at the start of communication, the cellular communication was disconnected not only when the distance to the communicating partner terminal became short, but also for some reason. Even in this case, it is possible to continue communication while switching to ad hoc communication and specifying the other party.

  Although the present invention has been described with reference to the above-described embodiment, it is not limited to this embodiment. Therefore, what is implemented as a change aspect without deviating from the meaning of the present invention is also included.

It is a block diagram which shows the circuit structure of the radio | wireless terminal which concerns on one embodiment of this invention. It is explanatory drawing which shows notionally the state in cellular communication by a terminal. It is explanatory drawing which shows notionally the state after moving to an ad hoc communication possible area in the cellular communication by a terminal. It is explanatory drawing which shows notionally the state during the ad hoc communication by a terminal. It is a conceptual explanatory drawing which shows the update process of BSSID. 7 is a flowchart (part 1) showing a flow of basic operation of a master terminal in a handoff process from cellular communication to ad hoc communication by the wireless terminal of FIG. 1; FIG. 6 is a flowchart (part 2) illustrating a flow of basic operation of a master terminal in handoff processing from cellular communication to ad hoc communication by the wireless terminal of FIG. 1. 4 is a flowchart (part 1) illustrating a flow of a basic operation of a slave terminal in a handoff process from cellular communication to ad hoc communication by the wireless terminal of FIG. 1; 6 is a flowchart (part 2) illustrating a flow of a basic operation of a slave terminal in a handoff process from cellular communication to ad hoc communication by the wireless terminal of FIG. 1. 3 is a flowchart showing a flow of an operation when a master terminal is disconnected in a handoff process from cellular communication to ad hoc communication by the wireless terminal of FIG. 1. 2 is a flowchart showing a flow of an operation when a slave terminal is disconnected in a handoff process from cellular communication to ad hoc communication by the wireless terminal of FIG. 1. 6 is a flowchart showing a flow of operation 1 during ad hoc communication by the wireless terminal of FIG. 1. 7 is a flowchart showing a flow of operation 2 during ad hoc communication by the wireless terminal of FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Wireless terminal 11 Cellular communication part 12 Ad hoc communication part 13 BSSID production | generation part 14 Ad hoc information storage part 15 Location information acquisition part 16 Position information transmission / reception part 17 Position information determination part 18 Ad hoc availability response transmission / reception part 19 Input part 20 Display part 21 Timer part 22 Interrupt setting unit 23 Control unit 24 Counterpart terminals 25a to 25d Other terminals A, B Ad hoc network

Claims (4)

An ad hoc communication unit that performs ad hoc communication with one or more other wireless terminals;
An infrastructure network communication unit that communicates with other wireless terminals via an infrastructure network base station;
A BSSID generator for generating a BSSID for use in the ad hoc communication;
A storage unit for storing the BSSID generated by the BSSID generation unit;
A determination unit that determines whether or not a probe request received by the ad hoc communication unit includes the same BSSID as the BSSID stored in the storage unit;
A communication switching unit that switches a communication path of communication being executed in the infrastructure network communication unit to the ad hoc communication unit,
The infrastructure network communication unit
The BSSID generated by the BSSID generation unit at the start of communication is transmitted to the other wireless terminal via the base station of the infrastructure network,
A probe request is received by the ad hoc communication unit during communication execution by the infrastructure network, and the determination unit determines that the probe request includes the same BSSID as the BSSID stored in the storage unit The ad hoc communication unit performs ad hoc connection with a wireless terminal that is a transmission source of the probe request, and the communication switching unit switches the communication path from the infrastructure network communication unit to the ad hoc communication unit. . It further includes a position information acquisition unit that acquires its own position information,
The infrastructure network communication unit
The wireless terminal according to claim 1, wherein the position information acquired by the position information acquisition unit is periodically transmitted to the other wireless terminal. An ad hoc communication unit that performs ad hoc communication with one or more other wireless terminals;
An infrastructure network communication unit that communicates with other wireless terminals via an infrastructure network base station;
A storage unit for storing a BSSID received by the infrastructure network communication unit;
A determination unit that determines whether or not the probe response received by the ad hoc communication unit includes the same BSSID as the BSSID stored in the storage unit;
A communication switching unit that switches a communication path of communication being executed in the infrastructure network communication unit to the ad hoc communication unit,
The ad hoc communication unit
During execution of communication by the infrastructure network, a probe request including a BSSID stored in the storage unit is transmitted,
When the determination unit determines that the same BSSID as the BSSID stored in the storage unit is included in the probe response received by the ad hoc communication unit, the ad hoc communication unit is the source of the probe response. An ad hoc connection with a wireless terminal, and the communication switching unit switches the communication path from the infrastructure network communication unit to the ad hoc communication unit. It further includes a position information acquisition unit that acquires its own position information,
The ad hoc communication unit
The probe request transmission is started based on a comparison result between the position information of the other wireless terminal periodically received by the infrastructure network communication unit and the position information periodically acquired by the position information acquisition unit. The wireless terminal according to claim 3, wherein:

Images