Abstract:
A mobile phone performs a search operation for searching for a communicable access point when a state of being able to communicate with an access point changes to a state of being unable to communicate. When a search operation is performed, the mobile phone displays that the search operation is being performed. In order to reduce power consumption, when the mobile phone displays that the search operation is being performed, the search operation is halted in response to acceptance of an input of an instruction to halt the search operation.

Description:
[0001]    This application is a continuation of U.S. patent application Ser. No. 11/727,220 filed Mar. 26, 2007, which claims priority to Japanese Patent Application No. 2006-089087 filed on Mar. 28, 2006, the entire contents of which are hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a mobile communication terminal, and more particularly to a mobile communication terminal connectable to a wireless LAN, a communication control method performed in the mobile communication terminal, and a communication control program recorded on a computer readable recording medium. 
         [0004]    2. Description of the Related Art 
         [0005]    A mobile phone which wirelessly communicates with a base station by radio cannot communicate in a location outside a communication area where radio waves are not transmitted or in a location with poor reception even within the communication area. In this case, the mobile phone indicates out-of-service on its display to notify a user that he cannot communicate. Japanese Patent Laying-Open No. 2005-20110 discloses a mobile phone which indicates on a display portion that it is unable to communicate when the mobile phone is located out of a service area of a radio base station or when an interference radio wave interferes with a reception radio wave. The mobile phone includes a determination means for determining a state in which the mobile phone is located out of the service area and a state in which the interference radio wave interferes with the reception radio wave and notifying a user of the determination result. 
         [0006]    However, in a case of a wireless LAN (Local Area Network), one mobile communication terminal may be included in the areas of access points of different kinds of LANs. In this case, the mobile communication terminal is connected to a wireless LAN selected from a plurality of wireless LANs. Furthermore, the mobile communication terminal may not be located within the service area of access point of one kind of wireless LAN but may be located within the service area of access point of another kind of wireless LAN. For example, when the mobile communication terminal moves from within the service area of one kind of wireless LAN out of that service area, the location after moving may be out of the service areas of all wireless LANs or may be within the service area of another kind of wireless LAN. The communication terminal searches for a wireless LAN that it can communicate with, and then automatically connects to the detected wireless LAN, in order to connect to the wireless LAN that it has communicated with or another wireless LAN to maintain the communication. Therefore, mere movement of the mobile communication terminal out of a service area of a wireless LAN consumes much power. In particular, since a mobile communication terminal is driven by a battery with a limited storage capacity, power consumption is preferably reduced as much as possible. 
         [0007]    On the other hand, a user can empirically know whether within a service area of a wireless LAN or outside a service area. The user may know beforehand a location where a wireless LAN cannot be detected even if a connectable wireless LAN is searched for. However, the user does not know that the mobile communication terminal automatically searches for a wireless LAN in such a location and therefore cannot stop the search, thereby wasting the power. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention is made to solve the aforementioned problem. An advantage of the present invention is to provide a mobile communication terminal with reduced power consumption, a communication control method performed in the mobile communication terminal, and a communication control program recorded in a computer readable recording medium. 
         [0009]    In order to achieve the aforementioned advantage, in accordance with an aspect of the present invention, a mobile communication terminal includes: a wireless communication portion to be able to wirelessly communicate with a radio station apparatus; a search portion to perform a search operation for searching for a radio station apparatus with which communication is possible, when the wireless communication portion changes from a state of being able to communicate with the radio station apparatus to a state of being unable to communicate; a search state display portion to display that the search operation is being performed; and a halt portion to halt the search operation in response to acceptance of an input of an instruction to halt the search operation. 
         [0010]    In accordance with another aspect of the present invention, a communication control method is performed in a mobile communication terminal including a wireless communication portion which is able to communicate with a radio station apparatus. The method includes the steps of: performing a search operation for searching for a radio station apparatus with which communication is possible, when the wireless communication portion changes from a state of being able to communicate with the radio station apparatus to a state of being unable to communicate; displaying that the search operation is being performed; and halting the search operation in response to acceptance of an input of an instruction to halt the search operation. 
         [0011]    In accordance with a further aspect of the present invention, a communication control program is executed in a mobile communication terminal including a wireless communication portion being able to wirelessly communicate with a radio station apparatus and is stored in a computer readable recording medium. The program causes the mobile communication terminal to perform the steps of: performing a search operation for searching for a radio station apparatus with which communication is possible, when the wireless communication portion changes from a state of being able to communicate with the radio station apparatus to a state of being unable to communicate; displaying that the search operation is being performed; and halting the search operation in response to acceptance of an input of an instruction to halt the search operation. 
         [0012]    The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  shows an overview of a communication system in an embodiment of the present invention. 
           [0014]      FIG. 2A  and  FIG. 2B  are perspective views showing an external view of a mobile phone in an embodiment of the present invention. 
           [0015]      FIG. 3  is a functional block diagram showing an exemplary function of the mobile phone in the present embodiment. 
           [0016]      FIG. 4  is a flowchart illustrating an exemplary flow of a process during communication. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0017]    In the following, an embodiment of the present invention will be described with reference to the figures. In the following description, the same parts will be denoted with the same reference characters. The designations and functions are also the same. Therefore, a detailed description thereof will not be repeated. 
         [0018]      FIG. 1  shows an overview of a communication system in an embodiment of the present invention. Referring to  FIG. 1 , the communication system includes a mobile phone  1  and three access points (AP)  100 - 102 . Here, for the sake of illustration, three access points  100 - 102  are shown. However, the number of access points is not limited as long as one or more access points are provided. Access points  100 - 102  are radio station apparatuses which function as relays for different kinds of LANs. Here, a LAN to which access point  100  is connected is referred to as a first network, a LAN to which access point  101  is connected is referred to as a second network, and a LAN to which access point  102  is connected is referred to as a third network. For example, the first network is a LAN installed at home by a user on his own, the second network is a LAN provided by Company A, and the third network is a LAN provided by Company B. 
         [0019]    Mobile phone  1  wirelessly communicates with any one of access points  100 - 102 . For example, when mobile phone  1  wirelessly communicates with access point  100 , mobile phone  1  is connected to the first network so that mobile phone  1  can communicate with another computer connected to the first network. 
         [0020]    Usually, access points  100 - 102  are fixedly installed on the ground, each defining a communicable range. When mobile phone  1  is located within a communicable range  100 A for access point  100 , mobile phone  1  can wirelessly communicate with access point  100 . However, when mobile phone  1  is located outside of communicable range  100 A, mobile phone  1  cannot wirelessly communicate with access point  100 . When mobile phone  1  is located within a communicable range  101 A for access point  101 , mobile phone  1  can wirelessly communicate with access point  101 . However, when mobile phone  1  is located outside of communicable range  101 A, mobile phone  1  cannot wirelessly communicate with access point  101 . When mobile phone  1  is located within a communicable range  102 A for access point  102 , mobile phone  1  can wirelessly communicate with access point  102 . However, when mobile phone  1  is located outside of communicable range  102 A, mobile phone  1  cannot wirelessly communicate with access point  102 . 
         [0021]    Among communicable range  100 A for access point  100 , communicable range  101 A for access point  101 , and communicable range  102 A for access point  102 , there exist a region in which three of them overlap each other, a region in which two of them overlap each other, and a region in which none of them overlap. When mobile phone  1  exists at a location shown in  FIG. 1 , that location is included in the region in which all of communicable ranges  100 A- 102 A for access points  100 - 102  overlap each other. Therefore, mobile phone  1  can wirelessly communicate with any of access points  100 - 102 . When mobile phone  1  communicates with any of access points  100 - 102 , for example, an identifier such as SSID (Service Set Identifier), ESSID (Extended SSID) or the like is used. Accordingly, even when mobile phone  1  is located in the region in which communicable ranges  100 A- 102 A overlap each other, mobile phone  1  can wirelessly communicate with one of access points  100 - 102  which is selected by mobile phone  1 . 
         [0022]      FIG. 2A  and  FIG. 2B  are perspective views showing an external view of a mobile phone in an embodiment of the present invention.  FIG. 2A  shows an external view of an open-style mobile phone and  FIG. 2B  shows an external view of a closed-style mobile phone. Referring to  FIG. 2A  and  FIG. 2B , a mobile phone  1  includes an operation-side portion  3  and a display-side portion  2 . Operation-side portion  3  includes an operation key  14  including a power key  14 A, a ten-key pad, a call key and the like and a microphone  13  arranged on the inner surface as well as a microphone terminal  16  and an earphone terminal  17  arranged on the right side surface. Display-side portion  2  includes a liquid crystal display (LCD)  15 , a first speaker  11  forming a receiver and a camera  24  arranged on the inner surface as well as a camera  24 A, a small-type LCD  15 A and a second speaker  12  arranged on the outer surface. Here, mobile phone  1  includes LCD  15  by way of example. However, LCD  15  may be replaced by an organic EL (Electro Luminescence) display. Operation-side portion  3  and display-side portion  2  are rotatably coupled to each other by a hinge mechanism, and operation-side portion  3  and display-side portion are openable/closable. The state of mobile phone  1  in which mobile phone  1  is folded and operation-side portion  3  and display-side portion  2  are in a closed state is referred to as a closed style. The state of mobile phone  1  in which mobile phone  1  is open and operation-side portion  3  and display-side portion  2  are in an open state is referred to as an open style. 
         [0023]      FIG. 3  is a function block diagram showing an exemplary function of the mobile phone in the present embodiment. Referring to  FIG. 3 , mobile phone  1  includes a control portion  21  for controlling mobile phone  1  as a whole, a radio circuit  22  connected to an antenna  22 A, a codec portion  28  for processing audio data, a switch portion  29  for switching input/output of codec portion  28 , microphone  13 , first speaker  11 , second speaker  12 , microphone terminal  16  and earphone terminal  17  each connected to switch portion  29 , a wireless LAN circuit  23  connected to an antenna  23 A, camera  24 , operation key  14  accepting an input of a user&#39;s operation, a posture detection switch  19 , a vibration portion  26 , a display control portion  30  for controlling display on LCD  15 , an ROM (Read Only Memory)  31  for storing a program executed in control portion  21  or the like, an RAM (Random Access Memory)  32  for use as a work area for control portion  21 , and an EEPROM (Electronically Erasable and Programmable ROM)  33  storing address book data, emails and the like in a nonvolatile manner. 
         [0024]    Posture detection switch  19  detects a relative position between operation-side portion  3  and display-side portion  2  and outputs the detected relative position to the control portion. Control portion  21  detects whether the posture of mobile phone  1  is in the closed style or in the open style, based on the output from posture detection switch  19 . 
         [0025]    Radio circuit  22  receives a radio signal received by antenna  22 A and outputs an audio signal produced by demodulating the radio signal to codec portion  28 . Radio circuit  22  also receives an audio signal from codec portion  28  and outputs a radio signal produced by modulating the audio signal to antenna  22 A. Codec portion  28  decodes an audio signal input from radio circuit  22 , converts the decoded digital audio signal into an analog signal, amplifies and then outputs the analog signal to switch portion  29 . Codec portion  28  also receives an analog audio signal from microphone  13  or microphone terminal  16  through switch portion  29 , converts and encodes the audio signal to a digital signal, and outputs the encoded audio signal to radio circuit  22 . 
         [0026]    Switch portion  29  is controlled by control portion  21  for switching input/output of an audio signal to codec portion  28 . Switch portion  29  outputs an audio signal accepted from codec portion  28  to any of earphone terminal  17 , first speaker  11  and second speaker  12 . When an earphone is connected to earphone terminal  17 , an audio signal accepted from codec portion  28  is output to earphone terminal  17 . When no earphone is connected to earphone terminal  17 , an audio signal accepted from codec portion  28  is output to second speaker  12 , if mobile phone  1  is in a hands-free mode, and an audio signal accepted from codec portion  28  is output to first speaker  11 , if mobile phone  1  is not in a hands-free mode. Mobile phone  1  is set to the hands-free mode by a user operating operation key  14 . Even if mobile phone  1  is not set to the hands-free mode in the open style during a call in progress, control portion  21  sets the hands-free mode, once the state of mobile phone  1  changes to the closed style. Therefore, switch portion  29  outputs the audio signal accepted from codec portion  28  to first speaker  11 , if mobile phone  1  is not set to the hands-free mode in the open style during a call in progress. However, once the state of mobile phone  1  changes to the closed style, switch portion  29  outputs the audio signal accepted from codec portion  28  to second speaker  12 . 
         [0027]    Switch portion  29  outputs an audio signal output by either microphone  13  or microphone terminal  16  to codec portion  28 . If a microphone is connected to microphone terminal  16 , switch portion  29  outputs the audio signal accepted from microphone terminal  16  to codec portion  28 . If no microphone is connected to microphone terminal  16 , switch portion  29  outputs the audio signal accepted from microphone  13  to codec portion  28 . 
         [0028]    Wireless LAN circuit  23  wirelessly communicates with any one of access points  100 - 102 . Wireless LAN circuit  23  detects a beacon signal output by access points  100 - 102  to detect whether communication is possible or not for each of access points  100 - 102 . Here, an operation of mobile phone  1  of detecting a beacon signal output by access points  100 - 102  is referred to as a search operation. Mobile phone  1  has two kinds of search operation. 
         [0029]    A first kind of search operation is an operation of specifying a network and determining whether connection to the specified network is possible or not. Specifically, a beacon signal output by an access point connected to the specified network is detected. Mobile phone  1  may conduct the first kind of search operation even when mobile phone  1  is not located within the communicable range of the access point connected to the specified network. For example, mobile phone  1  is wirelessly connected to access point  100 , by way of illustration. In this case, mobile phone  1  is located within communicable range  100 A of access point  100 . When mobile phone  1  moves out of communicable range  100 A, the intensity of radio waves received from access point  100  by mobile phone  1  weakens. If the intensity of radio waves received from access point  100  becomes smaller than a prescribed threshold value T 1 , or if a transfer rate becomes smaller than a prescribed threshold value T 2 , mobile phone  1  starts the first kind of search operation. Even if mobile phone  1  is located within communicable ranges  101 A,  102 A of any of access points  101 ,  102  other than access point  100  at the time when the first kind of search operation is started, mobile phone  1  conducts the first kind of search operation to detect a beacon signal output by access point  100 . When wireless communication with access point  100  is enabled during the first kind of search operation, mobile phone  1  wirelessly communicates with access point  100  again so that mobile phone  1  is connected to the first network. However, if a predetermined search time has elapsed without communication with access point  100  being enabled since the first kind of search operation was started, mobile phone  1  stops the first kind of search operation and then conducts the second kind of search operation. 
         [0030]    The second kind of search operation is an operation of determining whether connection with a plurality of networks preliminarily registered in mobile phone  1  is possible or not, one by one. Here, the second kind of search operation is conducted following the first kind of search operation, and therefore it is not determined whether connection with the first network subjected to the first kind of search operation is possible or not. Specifically, here, assuming that the first to third networks are registered in mobile phone  1 , it is determined whether a beacon signal output by access point  101  connected to the second network can be detected or not. If a beacon signal output by access point  101  can be detected, mobile phone  1  wirelessly communicates with access point  101 . However, if not detected, then it is determined whether or not a beacon signal output by access point  102  connected to the third network can be detected or not. If a beacon signal output by access point  102  can be detected, mobile phone  1  wirelessly communicates with access point  102 . However, if not detected, the second kind of search operation is ended. In short, mobile phone  1  determines whether connection with a plurality of networks preliminarily registered in mobile phone  1  is possible or not, one by one, and if connectable to any, mobile phone  1  connects to that network. However, if not connectable to any network, the second kind of search operation is ended. 
         [0031]    Display control portion  30  is controlled by control portion  21  for controlling LCD  15  according to an instruction input from control portion  21  and allowing an image to appear on LCD  15 . An image appearing on LCD  15  includes moving images and still images. 
         [0032]    A removable flash memory  27 A is inserted into card I/F  27 . Control portion  21  can access flash memory  27 A through card I/F  27 . Here, a program executed by control portion  21  is stored in ROM  31  by way of example. However, a program may be stored in flash memory  27 A and read from flash memory  27 A to be executed by control portion  21 . A recording medium storing a program is not limited to flash memory  27 A and may be a flexible disc, a cassette tape, an optical disc (CD-ROM (Compact Disc-ROM)/MO (Magnetic Optical Disc)/MD (Mini Disc)/DVD (Digital Versatile Disc)), an IC card (including a memory card), an optical card, a semiconductor memory such as a mask ROM, EPROM, or EEPROM, or the like. Alternatively, mobile phone  1  may be connected to the Internet through radio circuit  22  or wireless LAN circuit  23  so that a program is downloaded from a computer connected to the Internet and executed by control portion  21 . The program referred to herein includes not only a program directly executable by control portion  21  but also a source program, a compressed program, an encrypted program, or the like. 
         [0033]    Camera  24  includes a lens and a photoelectric transducer such as a COMS (Complementary Metal Oxide Semiconductor) sensor to focus light collected by the lens onto the COMS sensor. The COMS sensor performs photoelectric conversion of the received light and outputs image data to control portion  21 . Camera  24  is controlled by control portion  21  and starts picking up an image according to an instruction from control portion  21  to output the obtained still image data or moving image data to control portion  21 . Camera  24  includes an image processing circuit performing image processing for improving the image quality of image data and an A/D conversion circuit converting analog image data to digital image data. Control portion  21  outputs the still image data or moving image data output by camera  24  to display control portion  30  for display on LCD  15 , or encodes the still image data or moving image data in a compression encoding method for storage into EEPROM  34  or flash memory  27 A inserted in card I/F  27 . Camera  24  picks up an image of the user of mobile phone  1  when mobile phone  1  functions as a videophone. 
         [0034]    EEPROM  33  stores the respective identifiers of the first network, the second network and the third network. The identifier is preliminarily input and stored in EEPROM  33  by the user operating operation portion  14 . 
         [0035]      FIG. 4  is a flowchart illustrating an exemplary flow of a process during communication. The process during communication is a process performed by control portion  21  when control portion  21  executes a process-during-communication program. The process during communication is a process performed when mobile phone  1  connects to a wireless LAN for wireless communication. Here, mobile phone  1  wirelessly communicates with access point  100 , by way of example. When mobile phone  1  is in a state of being able to wirelessly communicate with access point  100 , mobile phone  1  displays “in service” on LCD  15  in order to indicate to the user that mobile phone  1  is located within the service area of access point  100 . Here, the display image “in service” appears at a location different from that of the display image “in service”, which appears on LCD  15  when mobile phone  1  is in a state of being able to communicate using radio circuit  22 . 
         [0036]    Referring to  FIG. 4 , it is determined whether or not the intensity of radio waves received from access point  100  becomes smaller than threshold value T 1  (step S 01 ). If the intensity of radio waves is smaller than threshold value T 1 , the process proceeds to step S 03 , and if not, the process proceeds to step S 02 . At step S 02 , it is determined whether or not the transfer rate becomes smaller than threshold value T 2  in wireless communication with access point  100 . If the transfer rate is smaller than threshold value T 2 , the process proceeds to step S 03 , and if not, the process returns to step S 01 . 
         [0037]    At step S 03 , the display image “in service” appearing on LCD  15  is switched to a display image “out of service 1”. Then, at step S 04 , access point  100  which has been communicated with is searched for. In other words, the first kind of search operation as described above is started. Therefore, the display image “out of service 1” is information indicating that mobile phone  1  conducts the first kind of search operation. 
         [0038]    At step S 05 , it is determined whether an instruction to stop the first kind of search operation is accepted or not. If an instruction to stop is accepted, the process proceeds to step S 14 . If an instruction to stop is not accepted, the process proceeds to step S 06 . When the user presses a predetermined stop key of operation keys  14 , control portion  21  detects the press on the stop key and accepts the instruction to stop the first kind of search operation. At step S 14 , the first kind of search operation is stopped and the process then ends. Accordingly, the first kind of search operation can be stopped on the user&#39;s own will, thereby preventing mobile phone  1  from conducting an unnecessary search and thus preventing wasted power consumption. 
         [0039]    At step S 06 , it is determined whether a communicable access point exists or not. Here, since the first kind of search operation is being executed, it is determined whether communication with access point  100  is enabled or not. If there exists a communicable access point, the process proceeds to step S 15 , and if not exist, the process proceeds to step S 07 . At step S 15 , connection with the first network is established by communicating with access point  100  with which communication is enabled. The process then ends. 
         [0040]    At step S 07 , it is determined whether the search time has elapsed or not since the first kind of search operation was started. If the search time has elapsed, the process proceeds to step S 08 , and if not, the process returns to step S 05 . Therefore, mobile phone  1  communicates with access point  100  when communication with access point  100  is enabled again by the time the search time has elapsed since the first kind of search operation was started. However, for example when the user moves out of communicable range  100 A of access point  100 , the execution of the first kind of search operation over the search time is stopped, thereby preventing wasted power consumption. 
         [0041]    At step S 08 , the display image “out of service 1” appearing on LCD  15  is switched to a display image “out of service 2”. Then, at step S 09 , the registered access points are searched one by one. In other words, the second kind of search operation as described above is started. Therefore, the display image “out of service 2” is information indicating that mobile phone  1  is conducting the second kind of search operation. 
         [0042]    At step S 10 , it is determined whether an instruction to stop the second kind of search operation is accepted or not. If an instruction to stop is accepted, the process proceeds to step S 16 , and if an instruction to stop is not accepted, the process proceeds to step S 11 . When the user presses a predetermined stop key of operation keys  14 , control portion  21  detects the press on the stop key and accepts the instruction to stop the second kind of search operation. At step S 16 , the second kind of search operation is stopped, and the process then ends. Therefore, the second kind of search operation can be stopped on the user&#39;s own will, thereby preventing mobile phone  1  from conducting an unnecessary search and thus preventing wasted power consumption. 
         [0043]    At step S 11 , it is determined whether a communicable access point exists or not. Here, since the second kind of search operation is being executed, it is determined whether communication with access point  101  is enabled or not. If a communicable access point exists, the process proceeds to step S 17 , and if not exist, the process proceeds to step S 12 . At step S 17 , wireless connection with access point  101  with which communication is enabled is established, and the process then ends. 
         [0044]    At step S 12 , it is determined whether the second kind of search operation is ended. If the second kind of search operation is ended, the process proceeds to step S 13 , and if not, the process returns to step S 10 . If the search has ended for all the networks, excluding the first network which was searched for in the first kind of search operation, among the registered networks, it is determined that the second kind of search operation is ended. Here, the third network has not yet been searched for, and therefore the process returns to step S 10 . 
         [0045]    At step S 13 , the display image “out of service 2” appearing on LCD  15  is switched to a display image “out of service 3”. When “out of service 3” is displayed, the second kind of search operation has ended, and therefore the display image “out of service 3” is information indicating that the search is ended. When the process proceeds to step S 13 , wireless LAN circuit  23  is not activated so that power consumption by wireless LAN circuit  23  is the lowest. 
         [0046]    Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.