Patent Publication Number: US-2009232117-A1

Title: Wireless communication terminal and wireless communication terminal control method

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a wireless communication terminal, a wireless communication terminal control method, and a wireless communication terminal control program that perform first wireless communication via a base station in a wireless public network, and perform second wireless communication via a wireless local area network (LAN) access point in a wireless LAN communication network having a smaller area than that of the wireless public network. 
     2. Description of the Related Art 
     A mobile phone (for example, a fixed mobile convergence (FMC) terminal, and a dual terminal) having a public network having a wide area (for example, freedom of mobile multimedia access (FOMA)), and a wireless communication network having a small area such as wireless local area network (WLAN) has been known. Such a mobile phone makes a call by data communication and voice over internet protocol (VOIP) in a communication area of WLAN-Access Point (AP), and performs operation of receiving Beacon in the absence of a call by the data communication and the VOIP. In the area outside WLAN-AP, the operation of receiving Beacon is stopped, and operation of scanning outside the WLAN area is performed regularly (see  FIG. 19 ). A scan interval of the scan operation is set shorter so that connection can be established soon after entering the WLAN-AP. 
     When a mobile terminal is out of the WLAN-AP, a power source for WLAN can be turned off manually, but if a user forgets to turn off the power source, the scan operation is performed, and unnecessary electricity is consumed (see  FIG. 20 ). For example, the user goes to a business trip without turning off the power source for WLAN, electricity is consumed by unintended scan operation, and the mobile terminal cannot be used as a telephone. 
     Techniques for solving unnecessary scan operation include a method disclosed in Japanese Patent Application Laid-open No. 2007-116294 in which a contactless integrated circuit (IC) card is attached to a terminal, an entrance/exit managing apparatus (card reader) is prepared, IC card information is rewritten at the time of exit, and thereby a power source for WLAN is turned off. Moreover, Japanese Patent Application Laid-open No. 2006-295643 discloses a method of turning on/off the power source for WLAN by a mobile phone base station notifying the terminal of a wireless LAN base station information in the base station. 
     As a technique for solving unnecessary scan operation, a method of increasing the scan interval gradually, reducing the number of times of the scan operation, and suppressing consumed electricity is disclosed in Japanese Patent Application Laid-open No. 2006-13594. Japanese Patent Application Laid-open No. 2005-229399 discloses a method of turning on/off the power source for WLAN by acquiring position information using global positioning system (GPS), and specifying WLAN areas. 
     The technique of Japanese Patent Application Laid-open No. 2007-116294 has a problem that many additional facilities are required and the cost increases because an entrance/exit managing apparatus needs to be provided. The technique of Japanese Patent Application Laid-open No. 2006-295643 has a problem that it is not suited for the access point for use by a corporation (company) and an individual and a complicate system architecture including a carrier is necessary because a mobile phone base station notifies a terminal of wireless LAN base station information in the base station. 
     The technique of Japanese Patent Application Laid-open No. 2006-13594 has a problem that response at the time of restoration deteriorates because a scan interval is increased gradually. The technique of Japanese Patent Application Laid-open No. 2005-229399 has a problem that electricity is consumed for position detection by GPS because position information is acquired by using GPS. 
     SUMMARY 
     It is an object of the present invention to at least partially solve the problems in the conventional technology. 
     According to an aspect of the present invention, a wireless communication terminal performs first wireless communication via a base station in a public network, and second wireless communication via a wireless LAN access point in a wireless LAN communication network that has a smaller area than that of the wireless public network. The wireless communication terminal includes a base station profile storing unit that stores position information transmitted from the base station, and a wireless LAN profile that is wireless LAN access point information in a communication area of the base station, in association with the position information; a current position information receiving/storing unit that acquires and stores therein current position information of the wireless communication terminal from the base station; a wireless profile setting unit that reads out a wireless LAN profile corresponding to the current position information acquired by the current position acquiring/storing unit from the base station profile storing unit, and sets the wireless LAN profile; and a wireless profile scan unit that scans the wireless LAN access point with the wireless LAN profile that is set by the wireless profile setting unit when the wireless communication terminal is out of a communication service area of the wireless LAN access point. 
     According to another aspect of the present invention, a method is for performing first wireless communication via a base station in a public network, and second wireless communication via a wireless LAN access point in a wireless LAN communication network that has a smaller area than that of the wireless public network. The method includes storing, in a base station profile storing unit, position information transmitted from the base station, and a wireless LAN profile that is wireless LAN access point information in a communication area of the base station, in association with the position information; acquiring current position information of the wireless communication terminal from the base station; reading out a wireless LAN profile corresponding to the acquired current position information from the base station profile storing unit; setting the wireless LAN profile; and scanning the wireless LAN profile set by the setting when the wireless communication terminal is out of a communication service area of the wireless LAN access point. 
     According to still another aspect of the present invention, a computer program product causes a computer to perform the method according to the present invention. 
     The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         FIG. 1  is a schematic for explaining an outline and features of a mobile phone terminal according to a first embodiment of the present invention; 
         FIG. 2  is a block diagram of the mobile phone terminal  10  according to the first embodiment shown in  FIG. 1 ; 
         FIG. 3  is a table for showing an example of a public wireless base station WLAN profile association table; 
         FIG. 4  is a table for showing an example of a scan profile storing unit when out of the WLAN service area; 
         FIG. 5  is a diagram for explaining registration process by an operation; 
         FIG. 6  is a schematic for explaining position information registration process; 
         FIG. 7  is a flowchart for showing an operation of scan profile setting process by the mobile phone terminal  10  according to the first embodiment shown in  FIG. 1 ; 
         FIG. 8  is a flowchart for showing an operation of scan interval setting processing by the mobile phone terminal  10  according to the first embodiment shown in  FIG. 1 ; 
         FIG. 9  is a flowchart for showing an operation of profile registration processing of the mobile phone terminal  10  according to the first embodiment shown in  FIG. 1 ; 
         FIG. 10  is a table for showing an example of a public wireless base station WLAN profile association table  14   b  held by a mobile phone terminal  10   a  according to a second embodiment of the present invention; 
         FIG. 11  is a schematic for explaining processing of registration for each wireless channel, 
         FIG. 12  is a flowchart for explaining procedure of registration for each wireless channel of the mobile phone terminal  10   a  according to the second embodiment; 
         FIG. 13  is a schematic for explaining processing of table auto-registration; 
         FIG. 14  is a flowchart for showing processing operation of the table auto-registration; 
         FIG. 15  is a schematic for explaining scan interval setting process 
         FIG. 16  is a schematic for explaining scan processing after a mobile phone terminal  10   b  according to a third embodiment of the present invention goes out of the WLAN service area; 
         FIG. 17  is a flowchart for explaining procedure of scan processing after the mobile phone terminal  10   b  according to the third embodiment goes out of the WLAN service area; 
         FIG. 18  is a flowchart for explaining procedure of another scan processing after the mobile phone terminal  10   b  according to the third embodiment goes out of the WLAN service area; 
         FIG. 19  is a schematic for explaining a conventional technique; and 
         FIG. 20  is a schematic for explaining a conventional technique. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     A wireless communication terminal, a wireless communication terminal control method, and a wireless communication terminal control program according to exemplary embodiments of the present invention will be explained below in detail with reference to accompanying drawings. 
     In the following, an outline and features of a mobile phone terminal according to a first embodiment of the present invention, a configuration and a flow of processing of the mobile phone terminal, and finally effects of the first embodiment will be explained. In the following example, a fixed mobile convergence (FMC) terminal and a dual terminal are exemplified as mobile phone terminals having both a wide-area public network (FOMA, for example), and a small-area wireless communication network such as WLAN. 
     An outline and features of a mobile phone terminal according to the first embodiment will be explained with reference to  FIG. 1 .  FIG. 1  is a schematic for explaining the outline and the features of the mobile phone terminal according to the first embodiment. 
     A mobile phone terminal  10  according to the first embodiment can perform both a wireless communication via a FOMA wireless base station  20  (hereinafter, a public wireless base station) in a wireless public network, and a wireless communication via a WLAN access point in a WLAN communication network having a smaller area than that of the wireless public network. The mobile phone terminal  10  can be realized with less cost and with a simple configuration, and provides a significant power saving effect. 
     Explaining specifically about its main features, as shown in  FIG. 1 , the mobile phone terminal  10  has a public wireless base station WLAN profile association table  14   b  that stores position information acquired from a base station, names of wireless LAN profiles that are wireless LAN access point information in a communication area of the public wireless base station, and wireless channels in the profiles, in association with each other. 
     In this configuration, the mobile phone terminal  10  receives and stores therein its current position information from a public wireless base station  20  (see ( 1 ) in  FIG. 1 ). Specifically, the mobile phone terminal  10  receives the position information every 2.56 seconds by a cellular system, and when the information is different from that stored in the mobile phone terminal  10  starts position information registration with the terminal (see  FIG. 6  described below). 
     The mobile phone terminal  10  reads out a profile name corresponding to the acquired current position information from the public wireless base station WLAN profile association table  14   b,  and sets the read WLAN profile as a scan profile (see ( 2 ) in  FIG. 1 ). 
     The mobile phone terminal  10  then scans the wireless LAN access point with the set WLAN profile at the time when it is out of the WLAN service area, that is when it is out of the communication area of the wireless LAN access point (see ( 3 ) in  FIG. 1 ). In other words, explaining with reference to the example shown in  FIG. 1 , the mobile phone terminal  10  scans the wireless LAN access point with “Profile 1 ” and “Profile 2 ” in a public wireless base station “A”, and the mobile phone terminal  10  scans the wireless LAN access point with only “Profile 3 ” in a public wireless base station “B”. 
     The mobile phone terminal  10  turns off power source for WLAN when it is out of the WLAN service area, and the WLAN profile is not set in the public wireless base station WLAN profile association table  14   b,  that is when the WLAN profile is not present in the public wireless base station  20  (see ( 4 ) in  FIG. 1 ). 
     As described above, the mobile phone terminal  10  turns on/off the power source for WLAN depending on a public wireless base station area, unnecessary electricity for cellular search at the time when the mobile phone terminal  10  is out of the service area can be reduced, only necessary WLAN profiles are scanned at a location where they are necessary, and connection becomes available as soon as the mobile phone terminal  10  enters an access point. Accordingly, a mobile phone terminal that can be realized with less cost and a simple configuration, and provides a significant power saving effect can be provided as in its main features described above. 
     Configuration of Mobile Phone Terminal  10   
     The configuration of the mobile phone terminal  10  shown in  FIG. 1  will now be explained with reference to  FIG. 2 .  FIG. 2  is a block diagram of the mobile phone terminal  10  according to the first embodiment. As shown in  FIG. 2 , the mobile phone terminal  10  has a first RF transceiver  11 , a second RF transceiver  12 , a controller  13 , and a storing unit  14 . Processing of these units will be explained below. 
     The first RF transceiver  11  transmits and receives information wirelessly via the FOMA wireless base station  20  in the wireless public network. The second RF transceiver  12  transmits and receives information wirelessly via the WLAN access point in the WLAN communication network. 
     The storing unit  14  stores therein data and programs necessary for various processing by the controller  13 , and specifically includes a terminal position storing unit  14   a , the public wireless base station WLAN profile association table  14   b,  and a scan profile storing unit  14   c  for the time out of the WLAN service area, as the ones closely related to the present invention. The terminal position storing unit  14   a  stores terminal position information acquired by a terminal position acquiring unit  13   a  explained below. 
     The public wireless base station WLAN profile association table  14   b  stores as shown in  FIG. 3  position information acquired from the public wireless base station, names of wireless LAN profiles that are wireless LAN access point information in a communication area of the public wireless base station, and wireless channels in the profiles, in association with each other. 
     The scan profile storing unit  14   c  for the time out of the WLAN service area stores scan profiles at the time of scanning out of the WLAN service area set by a wireless profile registering unit  13   d  explained below. Specifically, the scan profile storing unit  14   c  for the time out of the WLAN area stores position information acquired from base stations and profile names in association with each other, as exemplified in  FIG. 4 . The stored profiles are scanned when out of the WLAN service area. 
     The controller  13  has an internal memory for storing therein a computer program specifying various processing procedures and required data, and performs various processing using the same. The controller  13  includes the terminal position acquiring unit  13   a,  a terminal position manager  13   b,  a wireless transceiver operation controller  13   c,  the wireless profile registering unit  13   d  and a power controller  13   e  as the ones closely related to the present invention. 
     The terminal position acquiring unit  13   a  receives and stores therein its current position information from the public wireless base station  20 . Specifically, the mobile phone terminal  10  receives position information every 2.56 seconds by a cellular system, and notifies the position information to the terminal position manager  13   b.    
     The terminal position manager  13   b  manages the received position information. Specifically, the terminal position manager  13   b  compares as shown in  FIG. 6  the position information notified from the terminal position acquiring unit  13   a  and position information stored in the terminal position storing unit  14   a,  and performs no processing if they are identical with each other. When they are not identical, the terminal position manager  13   b  starts position information registration process (cellular operation) with the terminal. 
     The terminal position manager  13   b  searches the public wireless base station WLAN profile association table  14   b  based on the position information, and reads out a profile name corresponding to the acquired position information. When a profile corresponding to the public wireless base station is present, the terminal position manager  13   b  sets the read profile name in the scan profile storing unit  14   c  for the time out of the WLAN service area, as a scan profile at the time of scanning out of the service area. 
     The wireless transceiver operation controller  13   c  scans the wireless LAN access point with the WLAN profile set by the terminal position manager  13   b  when out of the WLAN service area. Specifically, the wireless transceiver operation controller  13   c  reads out the scan profile storing unit  14   c  for the time out of the WLAN service area when scanning out of the service area when out of the WLAN service area, and when the WLAN profile is stored scans the wireless LAN access point with the read WLAN profile. When the WLAN profile is not set, the wireless transceiver operation controller  13   c  notifies the power controller  13   e  of this fact. When scanning the WLAN profile, scan intervals are set. This setting processing is explained in detail below with reference to  FIG. 8 . 
     The wireless profile registering unit  13   d  registers position information, and profiles in association with each other in the public wireless base station WLAN profile association table  14   b.  Specifically, when a WLAN profile is input by a manual operation with input keys, a complete button is pressed, and registration in association with the current public wireless base station is selected as shown in  FIG. 5 , the wireless profile registering unit  13   d  acquires current value data from the terminal position information, and rewrites data in the public wireless base station WLAN profile association table  14   b.    
     The power controller  13   e  controls to turn off a power source for WLAN when a profile corresponding to the public wireless base station is not present when out of the WLAN service area. Specifically, the power controller  13   e  turns off the power source for WLAN when notified by the wireless transceiver operation controller  13   c  that a WLAN profile is not set. 
     Processing by the mobile phone terminal  10  according to the first embodiment will now be explained with reference to  FIGS. 7 to 9 .  FIG. 7  is a flowchart for showing an operation of scan profile setting process by the mobile phone terminal  10  according to the first embodiment,  FIG. 8  is a flowchart for showing an operation of scan interval setting processing by the mobile phone terminal  10  according to the first embodiment, and  FIG. 9  is a flowchart for showing an operation of profile registration processing of the mobile phone terminal  10  according to the first embodiment. 
     As shown in  FIG. 7 , when the mobile phone terminal  10  receives position information from the public wireless base station (step S 101 ), the mobile phone terminal  10  determines whether the position information is identical with the terminal position information stored therein (step S 102 ), and when identical returns to the step S 101  without performing any processing. On the other hand, when the received position information and the stored position information are different, the mobile phone terminal  10  performs position registration process with the terminal (cellular operation) (step S 103 ). 
     Then, when an out-of-service transition flag is “1”, the mobile phone terminal  10  changes the flag to “0” (step S 104 ), searches the public wireless base station WLAN profile association table  14   b,  and calls up a profile name corresponding to the current position information (step S 105 ). 
     When the profile corresponding to the current position information is present as a result (YES at the step  106 ), the mobile phone terminal  10  sets the read profile name at the scan profile storing unit  14   c  for the time out of the WLAN service area as a scan profile for the time out of the service area (step S 107 ). 
     On the other hand, when a profile corresponding to the public wireless base station is not present (NO at the step  106 ), the mobile phone terminal  10  determines the status of WLAN (step S 108 ). The mobile phone terminal  10  turns off power source for WLAN when out of the WLAN service area (step S 109 ), deletes a scan profile for the time scanning out of the WLAN service area (step S 110 ), and reduces wasteful power consumption. 
     Moreover, when the status of the WLAN is within the WLAN service area, the mobile phone terminal  10  performs table auto-registration process (step S 111 ). Explaining the table auto-registration process with reference to  FIG. 14 , the mobile phone terminal  10  acquires current position data from the terminal position information (step S 501 ), and acquires current WLAN profile data (step S 502 ) The mobile phone terminal  10  then rewrites data of the public wireless base station WLAN profile association table  14   b  (step S 503 ). Specifically, as shown in  FIG. 13 , the mobile phone terminal  10  controls to perform auto-registration when the area of the public wireless base station changes while staying in the WLAN service area. 
     Operation of the scan interval setting process will now be explained with reference to  FIG. 8 . As shown in  FIG. 8 , while the out-of-service transition flag is “0”, the mobile phone terminal  10  starts scanning the WLAN scan profile (steps S 201  and S 202 ), and then determines whether it is within or out of the WLAN service area (step S 203 ). When it is determined that the mobile phone terminal  10  is out of the service area as a result, the process proceeds to a step S 207 , and the mobile phone terminal performs the scan interval setting process. 
     On the other hand, when it is determined that the mobile phone terminal  10  is within the service area, the mobile phone terminal  10  determines whether it is within or out of the service area of a public network base station (step S 204 ). When the mobile phone terminal  10  is determined to be out of the service area as a result, the out-of-service area transition flag is set to “1” (step S 205 ), a scan program for the time out of the WLAN service area is called up (step S 206 ), and the scan interval setting process is performed. 
     In other words, the mobile phone terminal  10  determines whether the out-of-service transition flag is “0” or “1”, and when the out-of-service transition flag is “1”, sets the scan interval to be the shortest in the beginning, longer thereafter, and the longest in the end, as the scan interval setting process. When the out-of-service transition flag is “0”, the mobile phone terminal  10  sets the scan interval to be the longest. 
     Explaining the scan interval setting process with reference to  FIG. 15 , when the out-of-service transition flag is “1”, the position of the mobile phone terminal  10  is near the WLAN, the mobile phone terminal has just exited the WLAN area, and the possibility of the mobile phone terminal  10  soon returning to the WLAN area is high; therefore, the scan interval is set to be the shortest in the beginning, longer thereafter, and the longest in the end. When the out-of-service transition flag is “0”, the position of the mobile phone terminal  10  is far from WLAN, and the possibility of the mobile phone terminal  10  again returning to the WLAN is low; therefore, the scan interval is set to be the longest. 
     Thereafter, the mobile phone terminal  10  starts scan operation out of the service area (step S 210 ), and determines whether it is within or out of the WLAN service area (step S 211 ). When it is determined to be out of the service area as a result, the process returns to the step S 206 , and when it is determined to be within the service area, the process returns to the step S 204 . 
     Operation of manual profile registration process will now be explained with reference to  FIG. 9 . As shown in  FIG. 9 , when a WLAN profile is input by a manual operation with input keys (step S 301 ), a complete button is pressed (step S 302 ), and registration in association with the current public wireless base station is selected (YES at step S 303 ), the mobile phone terminal  10  acquires current value data from terminal position information (for example, public wireless base station ID) (step S 304 ), and rewrites data of the public wireless base station WLAN profile association table  14   b  (step S 305 ). 
     As described above, the mobile phone terminal  10  does not require such facilities as an entrance/exit managing apparatus or a card reader, and does not necessitate additional functions to be added to the public network; therefore, the mobile phone terminal  10  can be realized with less cost. The mobile phone terminal  10  can be used for a corporate access point or a personal access point and for an access point like a generally used hotspot, without depending on types of the access points. Moreover, it does not require position detection by GPS, and does not consume unnecessary electricity for on/off control of WLAN; therefore, the mobile phone terminal can be realized with less cost and with a simple configuration, providing a significant power saving effect. 
     In addition, according to the first embodiment, scan operation is stopped by turning off the power source for WLAN when a wireless profile related to terminal position information is not present; therefore, it is possible to provide a mobile phone terminal that provides a significant power saving effect. 
     Furthermore, according to the first embodiment, when it becomes out of the WLAN service area from within the service area, the profile is scanned such that the scan operation interval is the shortest in the beginning, and longer thereafter, and the profile is scanned such that the scan operation is long from the beginning when the acquired position information is changed and the position information is stored while it is out of the WLAN service area; therefore, it is possible to optimize the scan operation interval in accordance with the status of the terminal. 
     In the first embodiment, position information is registered in the public wireless base station WLAN profile association table  14   b  for each profile, but the present invention is not limited to this, and the position information may be registered for each wireless channel. 
     In the following, a second embodiment is explained with reference to  FIGS. 10 to 12 , in which position information is registered in the public wireless base station WLAN profile association table  14   b  for each wireless channel.  FIG. 10  is a table for showing an example of the public wireless base station WLAN profile association table  14   b  held by the mobile phone terminal  10   a  according to the second embodiment,  FIG. 11  is a schematic for explaining processing of registering position information for each wireless channel, and  FIG. 12  is a flowchart for explaining procedure of registering the position information for each wireless channel of the mobile phone terminal  10   a  according to the second embodiment. 
     An example of the public wireless base station WLAN profile association table  14   b  held by the mobile phone terminal  10   a  according to the second embodiment will be explained. As shown in  FIG. 10 , the public wireless base station WLAN profile association table  14   b  stores as in the first embodiment position information acquired from a base station, profile names, and wireless channels in the profiles in association with each other. Unlike the first embodiment, registration in the public wireless base station WLAN profile association table  14   b  according to the second embodiment is performed for each wireless channel. 
     Specifically, as shown in  FIG. 11 , although Profile 01  includes 14 channels (ch 1  to ch 14 ), actually only ch 1 , ch 6 , and ch 11  are used in some cases. In such cases, as shown in  FIG. 11 , when the mobile phone terminal  10   a  according to the second embodiment moves from the WLAN access point of ch 1  to the WLAN access point of ch 6 , the mobile phone terminal  10   a  automatically registers ch 6  in the public wireless base station WLAN profile association table  14   b.    
     Processing procedure of registration for each wireless channel of the mobile phone terminal  10   a  according to the second embodiment will be explained with reference to  FIG. 12 . The mobile phone terminal  10   a  receives beacon (step S 401 ), and determines whether the access point has changed based on the information included in the received beacon (step S 402 ). When the access point is determined to have changed as a result, the mobile phone terminal  10   a  calls up the public wireless base station WLAN profile association table  14   b  (step S 403 ). 
     The mobile phone terminal  10   a  then acquires current position data from the terminal position information (step S 404 ), acquires current WLAN profile data (step S 405 ), and rewrites data of the public wireless base station WLAN profile association table  14   b  (registers ch 6  in Profile 01  in the example shown in  FIG. 12 ) (step S 406 ). 
     As described above, only actually used channels are scanned in the second embodiment, and accordingly it is possible to provide a mobile phone terminal providing a more significant power saving effect. 
     In the present invention, after a mobile phone terminal goes out of a WLAN service area, only profiles and channels registered in a public wireless base station to which a profile used immediately before the mobile phone terminal goes out of the WLAN service area belongs may be scanned. 
     In the following, the mobile phone terminal  10   b  according to a third embodiment is explained with reference to  FIGS. 16 to 18 , in which profiles and channels registered in a public wireless base station to which a profile used immediately before the mobile phone terminal  10   b  goes out of a WLAN service area are scanned.  FIG. 16  is a schematic for explaining scan processing after the mobile phone terminal  10   b  according to the third embodiment goes out of a WLAN service area,  FIG. 17  is a flowchart for showing procedure of the scan processing after the mobile phone terminal  10   b  according to the third embodiment goes out of the WLAN service area, and  FIG. 18  is a flowchart for showing procedure of another scan processing after the mobile phone terminal  10   b  according to the third embodiment goes out of the WLAN service area. 
     The scan processing after the mobile phone terminal  10   b  goes out of the WLAN service area will be explained with reference to an example shown in  FIG. 16 . As shown in  FIG. 16 , the mobile phone terminal  10   b  performs reverse lookup of a table immediately after it goes out of a WLAN service area, and scans the wireless LAN access point with only profiles registered in a public wireless base station to which “Profile 01 ” used immediately before it goes out of the WLAN service area belongs (see ( 1 ) in  FIG. 16 ). 
     After an elapse of a predetermined length of time, the mobile phone terminal  10   b  scans the wireless LAN access point with all the profiles (see ( 2 ) in  FIG. 16 ). Other than changing profiles to be scanned at two steps as described above, profiles to be scanned may be changed at three steps: only immediately previous “Profile 01 ” just after the mobile phone terminal goes out of the WLAN service area; “Profile 01 ” and “Profile 02 ” registered in the public wireless base station to which Profile 01  belongs; and all the profiles. 
     The scan processing after the mobile phone terminal  10   b  according to the third embodiment goes out of the WLAN service area will be explained with reference to  FIGS. 17 and 18 .  FIG. 17  is for explaining the scan processing in a case of changing profiles to be scanned at two steps, and  FIG. 18  is for explaining the scan processing in a case of changing profiles to be scanned at three steps. 
     Specifically, as shown in  FIG. 17 , when the mobile phone terminal  10   b  goes out of the WLAN service area, (out of the WLAN service area at step S 601 ), the mobile phone terminal  10   b  acquires the WLAN profile used immediately before going out of the WLAN profile (step S 602 ), and specifies a public wireless base station associated with the profile acquired from the public wireless base station WLAN profile association table  14   b  (step S 603 ). 
     The mobile phone terminal  10   b  sets the profile corresponding to the specified public wireless base station as a scan profile for the time out of the WLAN service area (step S 604 ), and sets a timer  1  (step S 605 ). The mobile phone terminal  10   b  then determines whether a predetermined length of time has elapsed with the timer  1  (step S 606 ), and if not sets a scan interval (step S 607 ). 
     The mobile phone terminal  10   b  determines whether it is within or out of the WLAN service area (step S 609 ), and if within the WLAN service area resets the time  1 , and returns to the processing of the step S 601 , and if out of the WLAN service area repeats the processing of S 606  to S 609  until an elapse of a predetermined length of time. When the predetermined length of time has elapsed with the timer  1  (YES at step S 606 ), the mobile phone terminal  10   b  increases the scan profile for the time out of the WLAN service area to all the registered profiles (step S 610 ), sets the scan interval (step S 611 ), and starts scan operation out of the service area (step S 612 ). 
     Thereafter, the mobile phone terminal  10   b  determines whether it is within or out of the WLAN service area (step S 613 ), and if within the WLAN service area resets the timer  1  (step S 614 ), and the process returns to the processing at the step S 601 , and if out of the WLAN service area the process returns to the processing of the step S 611  and repeats the processing. 
     The scan processing in a case of changing profiles to be scanned at three steps will now be explained with reference to  FIG. 18 . As shown in  FIG. 18 , when the mobile phone terminal  10   b  goes out of the WLAN service area (out of the service area at step S 701 ), the mobile phone terminal  10   b  sets the timer  1  (step S 702 ), determines whether a predetermined length of time has elapsed (step S 703 ), and if not sets a scan interval (step S 704 ), and starts scan operation of a profile used immediately before going out of the service area (step S 705 ). The mobile phone terminal  10   b  determines whether it is within or out of the WLAN service area (step S 706 ), and if within the WLAN service area returns to the processing at the step S 701 , and if out of the WLAN service area repeats the processing at the steps S 703  to S 706  until an elapse of the predetermined length of time. 
     When the predetermined length of time has elapsed with the timer  1  (step S 703 ), the mobile phone terminal  10   b  sets a timer  2  (step S 707 ), and determines whether a predetermined length of time has elapsed with the timer  2  (step S 708 ). When the predetermined length of time has not elapsed after setting the timer  2  (NO at step S 708 ), the mobile phone terminal  10   b  calls up the scan profile when out of the WLAN service area (step S 709 ), sets a scan interval (step S 710 ), and starts scan operation out of the service area (step S 711 ). 
     The mobile phone terminal  10   b  then determines whether it is within or out of the WLAN service area (step S 712 ), and if within the WLAN service area returns to the processing at the step S 701 , and if out of the WLAN service area repeats the processing at the steps S 708  to S 712  until an elapse of the predetermined length of time. 
     On the other hand, when the predetermined length of time has elapsed after setting the timer  2  (YES at step S 708 ), the mobile phone terminal  10   b  increases the scan profile for the time out of the WLAN service area to all the registered profiles (step S 713 ), sets a scan interval (step S 714 ), and starts the scan operation out of the service area (step S 715 ). 
     Thereafter, the mobile phone terminal  10   b  determines whether it is within or out of the WLAN service area (step S 716 ), and if within the WLAN service area returns to the processing at the step S 701 , and if out of the WLAN service area repeats the processing of the steps S 714  to S 716  until an elapse of the predetermined length of time. 
     As described above, according to the third embodiment, immediately after the mobile phone terminal  10   b  goes out of the WLAN service area, only the profiles and the channels registered in the public wireless base station to which the profile used immediately before the mobile phone terminal  10   b  goes out of the WLAN service area belongs are scanned; therefore, it is possible to provide a mobile phone terminal having an improved responsiveness of re-connection when the mobile phone terminal returns to the WLAN service area immediately after it has gone out of the WLAN service area and providing a significant power saving effect. 
     Moreover, scan profiles to be scanned are changed in accordance with an elapse of time. For example, immediately after the mobile phone terminal goes out of the WLAN service area, a profile used immediately before is scanned because the possibility of the mobile phone terminal returning to the same WLAN service area is high. After an elapse of a predetermined length of time, all the profiles are scanned because it cannot be known to which WLAB service area the mobile phone terminal returns. Accordingly, it is possible to provide a mobile phone terminal having an improved responsiveness of re-connection and providing a significant power saving effect. 
     The present invention may be embodied in various forms other than the embodiments described above. Another embodiment of the present invention will be explained below as a fourth embodiment. 
     Among the processing explained in the embodiments, all or some of the processing explained to be performed automatically may be performed manually, and all or some of the processing explained to be performed manually may be performed automatically by known methods. In addition, processing procedure, control procedure, specific names, and information including various data and parameters shown in the document or drawings may be optionally modified unless otherwise noted. 
     All the components of the devices shown in the drawings are functionally and schematically explained, and it is not required that they are configured physically as shown. Specifically, dispersion and integration of each device are not limited to those shown in the drawings, and all or some of the devices can be dispersed or integrated functionally or physically in any unit in accordance with various load and use. All or some of the processing functions performed in each device may be realized by a central processing unit (CPU) and a computer program analyzed and performed by the CPU or may be realized as a hardware by hardware logic. 
     The wireless communication terminal control method explained in the embodiments may be realized by executing a preliminarily prepared computer program by a computer such as a personal computer or a workstation. This computer program can be distributed through a network such the Internet. Moreover, the computer program may be recorded on a recoding medium that can be read by a computer, such as a hard disk, flexible disc (FD), compact disc-read only memory (CD-ROM), magnetic optical disk (MO), and digital versatile disk (DVD), and may be executed by being read out from the recording medium by a computer. 
     The disclosed terminal does not require such facilities as an entrance/exit managing apparatus or a card reader, and does not need additional functions to be added to a public network; therefore, the terminal can be realized with low cost. Moreover, it can be used for any type of access points such as those for corporate use or personal use, and for generally used hotspot, without depending on types of the access points. Because it is not necessary to detect a position by using GPS, and thus unnecessary electricity is not consumed for on/off control of WLAN; a mobile phone terminal that can be realized with less cost and a simple configuration, and has a significant power saving effect can be advantageously provided. 
     Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.