Patent Publication Number: US-2010118848-A1

Title: Communication terminal and image data transfer method

Description:
TECHNICAL FIELD 
     The present invention relates to a communication terminal apparatus and image data transferring method. More particularly, the present invention relates to a communication terminal apparatus and image data transferring method for transferring image data using ad hoc mode communication of a wireless LAN. 
     BACKGROUND ART 
     Heretofore, to transfer an image taken by a camera such as a mobile telephone and digital camera to another device, it is known to store image data of the taken image once in a storage medium and then transfer the image data after connecting the storage medium having stored the image data to a device of transfer destination. 
     Further, heretofore, it is known to transfer image data of an image taken by a camera to a mobile telephone (e.g. see Patent Document 1). The camera system of Patent Document 1 registers the telephone numbers of mobile telephone apparatuses in a camera having a communication function. If a mobile telephone apparatus makes a call to the camera, the camera authenticates the access party with the registered telephone numbers, and allows only the mobile telephone apparatuses of the registered telephone numbers to transmit/receive data such as images and control signals to/from the camera. 
     Up till now, ad hoc mode communication of a wireless LAN is actively studied as on-demand type communication. 
     Ad hoc mode communication of a wireless LAN is communication of an autonomous-distributed network formed with radio terminals that can perform wireless connection (such as personal computers, PDAs and mobile telephones) without base stations and access points. Therefore, ad hoc mode communication of a wireless LAN can construct a network and communicate easily even in places without infrastructures such as access points 
     With this ad hoc mode communication of a wireless LAN, communication is performed between terminals using techniques such as the techniques of IEEE (Institute of Electrical and Electronics Engineers) 802.1 and Bluetooth (trademark). 
     Patent Document 1: Japanese Patent Application Laid-Open No. 2004-361464 
     DISCLOSURE OF INVENTION 
     Problems to be Solved by the Invention 
     However, a conventional apparatus has a problem that transferring image data is complicated when the image data is transferred via a storage medium. An example of this problem is that, when a group photograph is taken by a mobile telephone with camera or a digital camera, giving the photograph to all people in the photograph via a storage medium is laborious and complicated. 
     Further, the camera system of Patent Document 1 has a problem of requiring telephone number registration processing to register telephone numbers in the camera and requiring complicated processing to transfer image data from the camera to mobile telephones. There is another problem of requiring time to transfer image data because a communication scheme to transfer image data from a camera to mobile telephones employs FDMA, TDMA, CDMA and W-CDMA, whereby image data is transferred from the camera to the mobile telephones via a base station. 
     It is therefore an object of the present invention to provide a communication terminal apparatus and image data transferring method that can transfer image data of a taken image easily and transfer image data quickly using ad hoc mode communication of a wireless LAN. 
     Means for Solving the Problem 
     The communication terminal apparatus of the present invention employs a configuration having: an imaging section that takes an image; an activation detecting section that detects an activation of the imaging section; a searching section that searches for a communicating party terminal in a predetermined cycle that can communicate in ad hoc mode communication of a wireless local area network, the ad hoc mode communication of the wireless local area network directly communicating with the communicating party terminal using, as a start, a sign signal transmitted or received when the activation is detected in the activation detecting section; and a transferring section that, when the communicating party terminal is found by a search in the searching section, transfers image data of the image taken by the imaging section to the communicating party terminal in the ad hoc mode communication of the wireless local area network. 
     The image data transferring method of the present invention includes: in an imaging section that is provided in a communication terminal apparatus, taking an image; detecting an activation of the imaging section; in the communication terminal apparatus, searching for a communicating party terminal in a predetermined cycle that can communicate in ad hoc mode communication of a wireless local area network, the ad hoc mode communication of the wireless local area network directly communicating with the communicating party terminal using, as a start, a sign signal transmitted or received when the activation is detected in the activation detecting section; and, when the communicating party terminal is found by the search, transferring image data of the image taken by the imaging section to the communicating party terminal in the ad hoc mode communication of the wireless local area network. 
     ADVANTAGEOUS EFFECTS OF INVENTION 
     According to the present invention, it is possible to transfer image data of a taken image easily and transfer image data quickly using ad hoc mode communication of a wireless LAN. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram showing the configuration of a communication terminal apparatus according to an embodiment of the present invention; 
         FIG. 2  is a flowchart showing the operations of a communication terminal apparatus according to an embodiment of the present invention; 
         FIG. 3  is a diagram illustrating a condition of ad hoc mode communication according to an embodiment of the present invention; 
         FIG. 4  illustrates a timing chart diagram when ad hoc mode communication is performed according to an embodiment of the present invention; 
         FIG. 5  is a flowchart showing the operations of a communication terminal apparatus according to an embodiment of the present invention; and 
         FIG. 6  illustrates a timing chart diagram when ad hoc mode communication is performed according to an embodiment of the present invention. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     An embodiment of the present invention will be explained below in detail with reference to the accompanying drawings. 
     Embodiment 
       FIG. 1  is a block diagram showing the configuration of communication terminal apparatus  100  according to an embodiment of the present invention. 
     Antenna  101 , switching section  102 , transmitting section  103 , receiving section  104 , cellular power supply section  105  and cellular radio control section  106  form cellular communication section  150 . 
     Antenna  107 , switching section  108 , transmitting section  109 , receiving section  110 , WLAN power supply section  111  and WLAN radio control section  112  form WLAN communication section  160 . Cellular interface  113 , WLAN interface  114 , memory  115 , application control block  116 , WLAN activation request block  117  and imaging control section  118  form application communication control section  170 . 
     Antenna  101  receives and outputs a signal of a cellular communication scheme to switching section  102 , and transmits a transmission signal of the cellular communication scheme received as input from switching section  102 . 
     Switching section  102  switches between outputting a received signal received as input from antenna  101  to receiving section  104  and outputting a transmission signal received as input from transmitting section  103  to antenna  101 . 
     Transmitting section  103  performs up-conversion of a transmission signal received as input from cellular radio control section  106 , from a baseband frequency to a radio frequency, and outputs the result to switching section  102 . 
     Receiving section  104  performs down-conversion of the received signal received as input from switching section  102 , from a radio frequency to a baseband frequency, and outputs the result to cellular radio control section  106 . 
     Cellular power supply section  105  supplies power to cellular radio control section  106 . 
     Cellular radio control section  106  receives a supply of power from cellular power supply section  105 , and then modulates a transmission signal received as input from cellular interface  113  and outputs the result to transmitting section  103 . Cellular radio control section  106  also demodulates the received signal received as input from receiving section  104  and outputs the result to cellular interface  113 . 
     Antenna  107  receives a signal of ad hoc mode communication of a wireless LAN via a wireless ad hoc network and outputs it to switching section  108 , and transmits a transmission signal of ad hoc mode communication of the wireless LAN, received as input from switching section  108 , via the wireless ad hoc network. 
     Switching section  108  switches between outputting the received signal received as input from antenna  107  to receiving section  110  and outputting a transmission signal received as input from transmitting section  109  to antenna  107 . 
     Transmitting section  109 , which is a transfer means, performs up-conversion of a transmission signal received as input from WLAN radio control section  112 , from a baseband frequency to a radio frequency, and outputs the result to switching section  108 . 
     Receiving section  110  performs down-conversion of the received signal received as input from switching section  108 , from a radio frequency to a baseband frequency, and outputs the result to WLAN radio control section  112 . 
     WLAN power supply section  111  supplies power to WLAN radio control section  112  when receiving as input a search start signal from operation section  120 . 
     WLAN radio control section  112 , which is a searching means, is activated by receiving a supply of power from WLAN power supply section  111 . If activated WLAN radio control section  112  does not receive as input from receiving section  110  a beacon signal transmitted by the communicating party terminal, WLAN radio control section  112  generates a beacon signal and outputs it to transmitting section  109 . Here, when receiving as input a beacon cycle control signal to shorten the cycle of beacon transmission, from WLAN interface  114 , WLAN radio control section  112  outputs the generated beacon to transmitting section  109  at the time a beacon is transmitted in the cycle in accordance with the beacon cycle control signal. By contrast, if activated WLAN radio control section  112  receives as input a beacon signal transmitted from the communicating party terminal, from receiving section  110 , WLAN radio control section  112  generates an announcement traffic indication message (“ATIM”) signal and outputs the generated ATIM signal to transmitting section  109 . 
     When receiving as input an ACK for the ATIM signal from receiving section  110 , WLAN radio control section  112  modulates image data received as input from WLAN interface  114 , and outputs the result to transmitting section  109 . Further, with reference to the BSSID included in each frame of a received signal received as input from receiving section  110 , WLAN radio control section  112  processes only image data of a frame including the same BSSID as the BSSID currently assigned to WLAN radio control section  112 . WLAN radio control section  112  then outputs the processed image data to WLAN interface  114 . Here, a BSSID (Basic Service Set ID) is an identifier to identify an access point or base station, but the BSSID of the present embodiment has a role of identification information to identify groups of communication terminal apparatuses when the communication terminal apparatuses are grouped. In this case, the image data outputted from WLAN radio control section  112  to transmitting section  109  is image data of the image that is taken by camera module  119  and transferred to the communicating party, and the image data received as input in WLAN radio control section  112  from receiving section  110  is the image data to display image data of the image being taken by the communicating party terminal on LCD  121  as a monitor image. Further, WLAN radio control section  112  modulates a control signal, which is received as input from WLAN interface  114  and which is used to remote-operate imaging processing when the communicating party terminal takes an image, and outputs the result to transmitting section  109 . 
     Cellular interface  113  outputs a received signal received as input from cellular radio control section  106 , to application control block  116 . Further, cellular interface  113  outputs a transmission signal received as input from application control block  116 , to cellular radio control section  106 . 
     WLAN interface  114  requests an activation of WLAN radio control section  112  when receiving an activation request from WLAN activation request block  117 . After having requested the activation, WLAN interface  114  outputs image data received as input from application control block  116  to WLAN radio control section  112  and outputs a control signal received as input from imaging control section  118  to WLAN radio control section  112 , and outputs image data received as input from WLAN radio control section  112  to application control block  116 . Further, when receiving as input, from application control block  116 , a beacon cycle control signal to shorten the cycle of beacon transmission, WLAN interface  114  outputs the received beacon cycle control signal to WLAN radio control section  112 . 
     Memory  115 , which is a storage means, can store phonebook information (identification information), which is information about the destination address of a specific communicating party terminal. To be more specific, memory  115  stores the BSSID of IBSS (Independent Basic Service Set) as phonebook information. Further, memory  115  stores image data of an image, which is received as input from application control block  116  and taken by camera module  119 . Here, IBSS represents a wireless LAN network which does not use access points and in which a transmitter is a transmission source and a receiver is a communicating party. 
     When receiving as input a camera activation signal from operating section  120 , application control block  116 , which is an activation detecting means, detects the activation of camera module  119  and commands WLAN activation request block  117  to activate ad hoc mode communication of the wireless LAN in a predetermined cycle. In this case, with reference to memory  115 , if phonebook information is stored in memory  115 , application control block  116  outputs to WLAN interface  114  a beacon cycle control signal to shorten the cycle of beacon transmission, compared to a case where phonebook information is not stored in memory  115 . After having requested the activation, application control block  116  also outputs image data received as input from camera module  119 , to WLAN interface  114 . Further, application control block  116  outputs the image data received as input from WLAN interface  114 , to LCD  121 . Further, when receiving as input a signal in accordance with a key operation in operating section  120  from operating section  120 , application control block  116  performs predetermined application processing in accordance with the key operation. Further, application control block  116  inputs and outputs a cellular communication scheme signal with cellular interface  113  by performing predetermined application processing. Further, application control block  116  stores image data received as input from camera module  119  in memory  115  according to a command signal received as input from operating section  120 , which will be described later. 
     WLAN activation request block  117  requests an activation to WLAN interface  114  according to the command from application control block  116 . 
     Based on a signal received as input from operating section  120 , imaging control section  118  generates a control signal to control imaging processing by remote operations when the communicating party takes an image, and outputs the generated control signal to WLAN interface  114 . For example, imaging control section  118  generates a control signal for adjusting focus, or generates a control signal for adjusting the view angle of the camera. Further, when receiving as input a selection signal from operating section  120 , imaging control section  118  generates a control signal for requesting transmission of image data of the image, which is currently taken by the communicating party terminal, as a monitor image. 
     Camera module  119 , which is an imaging means, has an activation switch and is activated by a press of the activation switch. Further, after activation, camera module  119  takes an image of the object and outputs image data of the taken image of the object to application control block  116 . 
     Operating section  120 , which is a selecting means, has operation keys, and, when the operation keys are operated externally, outputs the signal in accordance with the key operation, to application control block  116 . Further, if the key operation controls imaging processing by remote operations in the case of imaging in the communicating party terminal, operating section  120  outputs a signal for remote operation associated with the key operation, to imaging control section  118 . Further, if the key operation commands displaying as a monitor image the image being taken by the communicating party terminal, operating section  120  outputs a selection signal for selecting displaying the monitor image, to imaging control section  118 . Further, if the key operation commands storing image data of the image taken by camera module  119 , operating section  120  outputs a command signal for commanding storing the image data, to application control block  116 . Further, operating section  120  has a camera activation switch and a search start switch of the WLAN communicating party terminal. When the camera activation switch is pressed, operating section  120  outputs a camera activation signal to application control block  116 . Further, when the search start switch of the WLAN communicating party terminal is pressed, operating section  120  outputs a search start signal to WLAN power supply section  111 . 
     LCD  121 , which is a display means, displays an image of image data received as input from application control block  116 . In this case, if the image data received as input from application control block  116  is image data of the image being taken by the communicating party terminal, LCD  121  displays, as a monitor image, the image being taken by the communicating party terminal. 
     Next, the operations of communicating terminal apparatus  100  in the case of transferring image data of a taken image to the communicating party terminal, will be explained using  FIG. 2 .  FIG. 2  is a flowchart showing the operations of communication terminal apparatus  100 . 
     First, communication terminal apparatus  100  accepts user operations (step ST 201 ). 
     Next, application control block  116  of communication terminal apparatus  100  decides whether or not the camera of camera module  119  is activated (step ST 202 ). 
     If the camera is not activated, communication terminal apparatus  100  accepts user operations again (step ST 201 ). 
     By contrast, if the camera is activated, application control block  116  of communication terminal apparatus  100  decides whether or not to activate a wireless LAN (“WLAN”) (step ST 203 ). 
     If the wireless LAN is not activated, communication terminal apparatus  100  keeps the activation of only camera module  119  (step ST 204 ). 
     By contrast, if the wireless LAN is activated in step ST 203 , application control block  116  decides whether phonebook information is stored in memory  115  and whether or not it is necessary to search for the phonebook information (step ST 205 ). 
     If it is necessary to search for the phonebook information, application control block  116  determines to change the beacon transmission cycle to be shorter (step ST 206 ). 
     By contrast, if it is not necessary to search for the phonebook information, application control block  116  sets the beacon transmission cycle to a normal cycle, that is, to a longer beacon cycle than the beacon cycle set in step ST 206  (step ST 207 ). 
     Next, WLAN radio control section  112  of communication terminal apparatus  100  decides whether or not connection is established with a wireless LAN connecting device (step ST 208 ). To be more specific, WLAN radio control section  112  transmits a beacon in the set beacon cycle and then transmits an ATIM signal. When receiving an ACK for the ATIM signal from the communicating party terminal, WLAN radio control section  112  decides that connection is established with the wireless LAN connecting device. Also, when receiving a beacon and ATIM signal transmitted from the communicating party terminal, WLAN radio control section  112  decides that connection is established with the wireless LAN connecting device. 
       FIG. 3  is a diagram illustrating a state of performing ad hoc mode communication, and  FIG. 4  is a timing chart diagram when ad hoc mode communication is performed. In  FIG. 3  and  FIG. 4 , communication terminal apparatus  100  has the same configuration as in  FIG. 1 . 
     Referring to  FIG. 3 , communication terminal apparatus  100  performs ad hoc mode communication with communicating party terminal B and does not perform ad hoc mode communication with communicating party terminal A. 
     In this case, referring to  FIG. 4 , communication terminal apparatus  100  transmits beacon # 401 . Further, with this transmission of beacon # 401  as a start, communication terminal apparatus  100  then transmits ATIM signal # 402  to communicating party terminal B by unicast. Communicating party terminal A having received ATIM signal # 402  does not participate in ad hoc mode communication with communication terminal apparatus  100 , and therefore does not transmit a response signal. On the other hand, communicating party terminal B having received ATIM signal # 402  that is directed to communicating party terminal B, participates in ad hoc mode communication with communication terminal apparatus  100 , and therefore transmits ACK # 403  in response to ATIM signal # 402 . When receiving ACK # 403 , communication terminal apparatus  100  can decide that communication terminal apparatus  100  is connected with the wireless LAN connecting device. Also, when communication terminal apparatus  100  cannot receive ACK # 403  or communicating party terminal B does not transmit ACK # 403 , communication terminal apparatus  100  can decide that communication terminal apparatus  100  is not connected with the wireless LAN connecting device. 
     In  FIG. 4 , communication terminal apparatus  100  and communicating party terminals A and B hold them for a random waiting time called “back-off” from the target beacon transmission time “TBTT,” which corresponds to the end time of the previous beacon period, and try to transmit a beacon signal. If communication terminal apparatus  100  and communicating party terminals A and B receive a beacon signal before their transmission time, they cancel transmission of pending beacon signals. By this means, in ad hoc mode communication, only one of communication terminal apparatus  100  and communicating party terminals A and B transmits a beacon signal. 
     A beacon frame needs to be processed by communication terminal apparatus  100  and communicating party terminals A and B, and, consequently, communication terminal apparatus  100  and communicating party terminals A and B each start and enter an activation state before the TBTT. Here, a beacon frame contains essential fields including the time stamp, beacon period, capability information, service set ID and support rate, and option fields including the FH parameter set, DS parameter set, CF parameter set, IBSS parameter set and TIM. Option information is present only when it needs to be used. 
     Returning to  FIG. 2 , if it is decided that connection is established with a wireless LAN connecting device in step ST 208 , communication terminal apparatus  100  starts ad hoc mode communication of the wireless LAN (step ST 209 ). 
     Next, communication terminal apparatus  100  performs negotiation with the communicating party terminal with which communication terminal apparatus  100  starts ad hoc mode communication of the wireless LAN, and decides whether or not negotiation connection is established (step ST 210 ). 
     If the negotiation connection can be established, communication terminal apparatus  100  and the communicating party terminal enter a connection state with a wireless LAN connecting device by ad hoc mode communication (step ST 211 ). 
     Next, camera module  119  takes an image of an object (step ST 212 ). 
     Next, application control block  116  of communication terminal apparatus  100  decides whether or not to store image data of the image taken by camera module  119  in memory  115  (step ST 213 ). 
     If it is decided not to store the image data in memory  115 , the process returns to camera display (step ST 214 ). 
     By contrast, if it is decided to store the image data in memory  115  in step ST  213 , application control block  116  stores the image data in memory  115  (step ST 215 ). 
     Next, WLAN radio control section  112  of communication terminal apparatus  100  starts transferring the image data to the communication terminal party having entered the connection state in step ST 211 , using ad hoc mode communication of the wireless LAN (step ST 216 ). To be more specific, as shown in  FIG. 4 , WLAN radio control section  112  transfers image data # 403 , and communicating party terminal B having received image data # 403  transmits an ACK (not shown) in response to the received image data. 
     On the other hand, if only camera module  119  is activated in step ST 204 , if it is decided that connection is not established with the wireless LAN connecting device in step ST 208 , if negotiation connection cannot be established in step ST 210 , or if process returns to camera display in step ST 214 , communication terminal apparatus  100  does not transfer image data. 
     Next, the operations of communication terminal apparatus  100  in the case where an image taken by a communicating party terminal is displayed as a monitor image, will be explained using  FIG. 5 .  FIG. 5  is a flowchart showing the operations of communication terminal apparatus  100 . 
     First, communication terminal apparatus  100  accepts user operations (step ST 501 ). 
     Next, camera module  119  of communication terminal apparatus  100  decides whether or not the camera is activated (step ST 502 ). 
     If the camera is not activated, communication terminal apparatus  100  accepts user operations again (step ST 501 ). 
     By contrast, if the camera is activated, application control block  116  of communication terminal apparatus  100  decides whether or not to activate a wireless LAN (“WLAN”) (step ST 503 ). 
     If the wireless LAN is not activated, communication terminal apparatus  100  keeps the activation of only camera module  119  (step ST 504 ). 
     By contrast, in step ST 504 , if the wireless LAN is activated, application control block  116  decides whether or not to receive as input, from operating section  120 , a signal selecting displaying the image being taken by the communicating party terminal, that is, whether or not to share the camera (step ST 505 ). 
     If the camera is shared, application control block  116  searches for phonebook information stored in memory  115  (step ST 506 ). 
     Next, application control block  116  determines to change the beacon transmission cycle to be shorter (step ST 507 ). 
     Next, WLAN radio control section  112  of communication terminal apparatus  100  decides whether or not connection is established with the wireless LAN connecting device (step ST 508 ). To be more specific, WLAN radio control section  112  transmits a beacon in the set beacon cycle and then transmits an ATIM signal. When receiving ACK for the ATIM signal from the communicating party terminal, WLAN radio control section  112  decides that connection is established with a wireless LAN connecting device. Also, when receiving a beacon and ATIM signal transmitted from the communicating party terminal, WLAN radio control section  112  decides that connection is established with a wireless LAN connecting device. Here, the determination method is the same as in  FIG. 3  and  FIG. 4 , and therefore detailed explanation will be omitted. 
     If it is decided that connection is established with a wireless LAN connecting device in step ST 508 , communication terminal apparatus  100  starts ad hoc mode communication of the wireless LAN (step ST 509 ). 
     Next, communication terminal apparatus  100  performs negotiation with the communicating party terminal with which communication terminal apparatus starts ad hoc mode communication of the wireless LAN, and decides whether or not negotiation connection is established (step ST 510 ). 
     If the negotiation connection is established, communication terminal apparatus  100  and the communicating party terminal enters a connection state with a wireless LAN connecting device by ad hoc mode communication (step ST 511 ). 
     Next, imaging control section  118  of communication terminal apparatus  100  generates a control signal for requesting transfer of the image data being taken by the communicating party terminal. Communication terminal apparatus  100  then transmits a control signal for requesting transfer of the image data being taken by the communicating party terminal. 
       FIG. 6  is a timing chart diagram when ad hoc mode communication is performed. In  FIG. 6 , the same components as in  FIG. 4  will be assigned the same reference numerals and their explanation will be omitted. 
     From  FIG. 6 , communication terminal apparatus  100  transmits control signal # 601  for requesting transfer of the image data being taken by the communicating party terminal, and the communicating party terminal B having received control signal # 601  transmits ACK # 602  in response to reception of control signal # 601 . 
     Next, as shown in  FIG. 6 , communication terminal apparatus  100  receives image data # 603  transmitted from the communicating party terminal (step ST 512 ). 
     Next, LCD  121  of communication terminal apparatus  100  displays image data received in step ST 512  as a monitor image (step ST 513 ). 
     On the other hand, if only camera module  119  is activated in step ST 504 , if the camera is not shared in step ST 505 , if it is decided that connection is not established with the wireless LAN connecting device in step ST 508 , or if negotiation connection cannot be established in step ST 510 , communication terminal apparatus  100  does not transfer image data. 
     By the way, as shown in  FIG. 4  and  FIG. 6 , a beacon signal represents a sign signal in ad hoc mode communication of the wireless LAN and is transmitted to all radio terminals. A beacon can be transmitted at predetermined intervals from any of communication terminal apparatus  100  and communicating party terminals A and B. 
     In response to this beacon, a time window called “ATIM window” starts in communication terminal apparatus  100  and communicating party terminals A and B. This ATIM window is a time nodes (here, communication terminal apparatus  100  and communication terminals A and B) must keep an active state. 
     In ad hoc mode communication, communication terminal apparatus  100  and communicating party terminals A and B transmit an ATIM signal during the ATIM window, whereby communicating party terminal A cannot turn the power supply “on” during the ATIM window, and the ATIM window ends a time determined upon establishing IBSS after the time the power is turned “on.” 
     Further, wireless terminal A has not transmitted or received an ATIM signal, and therefore can enter a sleep state (power saving mode) after the ATIM window ends. Further, radio terminal A is activated to transmit or receive a beacon signal in the beacon transmission cycle. 
     Also, if other communication terminal apparatuses than communicating party terminals A and B want to participate in a network that has already been structured, communication terminal apparatus  100  that transmits beacons does not enter a sleep state until the next beacon transmission, so as to give a chance to participate in the network to other communication terminal apparatuses that want to participate in the network. 
     By the way, communication terminal apparatus  100  and communicating party terminal B transmit and receive an ATIM signal during the ATIM window and therefore cannot enter a sleep state. 
     Also, communication terminal apparatus  100  having transmitted a beacon accepts a new entry of external radio terminals for ad hoc mode communication, and therefore cannot enter a sleep state. 
     In the ATIM window upon transmitting the next beacon, communication terminal apparatus  100  and communicating party terminals A and B do not transmit and receive an ATIM signal, and therefore communicating party terminals A and B, excluding communication terminal apparatus  100  having transmitted a beacon, enter a sleep state after the ATIM window ends. 
     The BSSID is stored in all frames such that communication terminal apparatuses and other devices can check data subjected to broadcasting or multicasting. By this means, only the communication terminal apparatuses and other devices that belong to the same BSSID can receive data subjected to broadcasting or multicasting. Further, three address fields are used in IBSS. The address of the receiver is stored in the first address field, and, in the case of IBSS, this address is the same as the address of the communicating party. The address of the transmission source is stored in the second address field. The BSSID is stored in the third address field. Further, the IBSS has only one parameter and ATIM windows. This field is only used in beacon frames in the IBSS. 
     Thus, according to the present embodiment, by transferring image data using ad hoc mode communication of a wireless LAN, it is possible to transfer image data of a taken image easily and transfer image data quickly. Further, upon distributing a group photograph or the like, the present embodiment can realize this easily. Further, the present embodiment can remote-operate a communicating party terminal while looking at a monitor display, so that it is possible to eliminate the process of repeating taking an image. Further, the present embodiment shortens the beacon cycle if phonebook information is stored, thereby enabling image data to be transferred quickly to a target party. 
     INDUSTRIAL APPLICABILITY 
     The communication terminal apparatus and image data transferring method according to the present invention are useful especially for transferring image data using ad hoc mode communication of a wireless LAN.