Patent Publication Number: US-2007123245-A1

Title: Communication system and communication terminal device

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a communication system which performs communication via a communication network, and a communication terminal device constituting the communication system.  
      2. Description of the Related Art  
      Conventionally, speech communication by using a telephone set and transmission/reception of an electronic mail by using a personal computer and the like have been widely utilized to communicate with a family or friends. By utilizing the communication means such as a telephone and an electronic mail, it is possible to easily communicate with a family and friends wherever and whenever desired.  
      In recent years, a portable telephone and a PDA (Personal Digital Assistant) are also used not only as a mere communication means but also as a photographing device for photographing a subject, a computer for browsing a website, a substitute of an alarm clock at a visiting place, and the like. Further, as a result of the communication charges being significantly reduced, the number of people who own a portable telephone and the like as a communication terminal device for their personal use has also been increasing. In such situations, manufacturers of the communication terminal devices have been competing in providing new facilities so as to make their communication terminal devices unique.  
      The functions which have been provided in recent years include a function to perform a high-speed data communication (for example, dual mode, HSDPA and the like) by utilizing a latest data compression technique and the like, a function to enhance the reception sensitivity of radio waves, a function to download a moving image, a game and the like, and a function to utilize a speech communication, an electronic mail and the like even abroad. However, since version-up after the purchase is not generally expected in the portable telephone and the like, there is a problem that a new communication terminal device must be newly purchased in order to use these functions.  
      For this problem, a technique is disclosed in a patent document 1: Japanese Patent Laid-Open No.10-135899, in which a relay device which relays a radio wave transmitted from a base station to a communication terminal device is used to transfer the radio wave to a communication terminal device existing in a location where the radio wave from the base station is difficult to be transmitted, and a technique is also disclosed in a patent document 2: Japanese Patent Laid-Open No. 2000-49690, in which a portable telephone existing in a communication area range where the portable telephone is capable of performing transmission/reception of a radio wave to/from a base station is used to transfer the radio wave to a portable telephone existing outside the communication area range. With the techniques disclosed in the patent document 1 and the patent document 2, a communication terminal device already possessed can be utilized over a wide range without a communication terminal device having a high reception sensitivity of radio waves being newly purchased.  
      However, the techniques disclosed in the patent document 1 and the patent document 2 are intended to perform communication even in the area where radio wave is difficult to be transmitted. Thus, even when communication accuracy is improved by using the techniques, the download function and the overseas communication function as described above can not be utilized by using a communication terminal device which is not provided with such functions, as a result of which a latest portable terminal device needs to be newly purchased. On the other hand, during overseas travel, it is also conceivable to rent a communication terminal device available in the country of a travel destination. However, in the rented communication terminal device, there are many cases where an address book in which contact destinations of a family and friends are registered is not prepared, and where explanation of operation elements is displayed by the language of the country. As a result, the need for using a familiar private communication terminal device as it is has been increasing.  
      The present invention has been made in view of the above circumstances and provides a communication system and a communication terminal device which are capable of utilizing various kinds of functions and services.  
     SUMMARY OF THE INVENTION  
      The present invention provides a communication system, having a first communication terminal device which performs peer-to-peer communication by a first communication system, and a second communication terminal device which performs peer-to-peer communication with the first communication terminal device by the first communication system and performs communication via a communication network by a second communication system,  
      the first communication terminal device including: a relay application section which applies for a relay of communication via the communication network to the second communication terminal device by the first communication system; and a relay result receiving section which receives by the first communication system a result of communication by the second communication system via the communication network performed by the second communication terminal device on the basis of an application from the relay application section,  
      the second communication terminal device including: an application receiving section which receives a communication relay application from the first communication terminal device by the first communication system; a relay communication section which performs, in response to receipt of an application by the application receiving section, communication via the communication network in accordance with the application; and a relay result transmitting section which transmits the result of communication performed by the relay communication section, by the first communication system to the first communication terminal device.  
      With the communication system according to the present invention, in the second communication terminal device, communication via the communication network is performed on the basis of the application from the first communication terminal device, and the communication result is transmitted to the first communication terminal device by peer-to-peer communication. Therefore, even in the case where functions such as to perform communication via a network, and to utilize a speech communication and an electronic mail abroad, are not loaded into the first communication terminal device, the network communication is vicariously performed by the second terminal device, and the communication result is transmitted to the first communication terminal device by peer-to-peer communication, as a result of which the functions can be utilized by the first communication terminal device.  
      Further, in the communication system according to the present invention, it is preferred that the relay application section applies for reception of data via the communication network,  
      that the relay communication section receives the data via the communication network, and  
      that the relay result transmitting section and the relay result receiving section perform transmission and reception of the data received by the relay communication section, respectively.  
      The data received by the relay communication section are transmitted by the relay result transmitting section to the first communication terminal device, so as to be received by the relay result receiving section of the first communication terminal device. Thereby, even in the case where a service function to download data via the network and the like is not provided for the first communication terminal device, the service function can be utilized by the first communication terminal device.  
      In addition, in the communication system according to the present invention, it is preferred that the first communication terminal device further performs communication via the communication network by a third communication system in addition to the peer-to-peer communication by the first communication system, and that the first communication terminal device has a first switching section to perform switching the communication by the third communication system and the communication relayed by the second communication terminal device in accordance with a user operation.  
      According to the preferred embodiment of the present invention, the communication system can be switched so as to correspond to a use purpose, such as for example being switched to communication relayed via the second communication terminal device when high-speed communication is desired to be performed despite high communication charges, or being switched to communication by the third communication system when communication charges are desired to be suppressed low.  
      Further, in the communication system according to the present invention, the first communication terminal device further includes a first searching section that performs a search operation on whether the second communication terminal device exists in a communicable range by the second communication system.  
      Whether the second communication terminal device exists in the communicable range or not is searched, and a relay application is sent to the searched second communication terminal device, as a result of which communication relayed by the second communication terminal device can be surely utilized.  
      Further, it is preferred that the communication system according to the present invention, has a base station which is connected to the communication network to relay communication, and at least one of the base station, the first communication terminal device and the second communication terminal device has a second switching section which performs a switching operation on whether the communication relay between the base station and the first communication terminal device by the second communication terminal device is permitted or not, and  
      that the application receiving section of the second communication terminal device receives a relay application only when communication relay is permitted by the second switching section.  
      The relay of communication is permitted by the second communication terminal device only when communication quality between the base station and the second communication terminal device can be ensured.  
      In the communication system according to the present invention, it is preferred that the relay application section of the first communication terminal device applies for communication relay, and applies for relay interruption to the second communication terminal device under communication relay, and  
      that the base station receives a communication stop request from the second communication terminal device under communication relay and a communication request from a new second communication terminal device, so as to stop communication with the second communication terminal device under communication relay and to start communication with the new second communication terminal device.  
      The stop of relay is applied from the first communication terminal device to the second communication terminal device, and communication with the new second communication terminal device is started by the base station, so that the second communication terminal device which relays communication can be switched without interrupting data transmission to the first communication terminal device.  
      The present invention also provides a communication terminal device, which performs peer-to-peer communication by a first communication system, including:  
      a relay application section which applies for relay of communication via a communication network to a second communication terminal device that performs peer-to-peer communication with the communication terminal device by the first communication system and that performs communication via the communication network by a second communication system; and  
      a relay result receiving section which receives a result of communication by the second communication system via the communication network performed by the second communication terminal device on the basis of an application from the relay application section, from the second communication terminal device by the first communication system.  
      With the communication terminal device according to the present invention, it is possible to make the second communication terminal devices vicariously perform communication via the communication network, so as to obtain the communication result via the second communication terminal device.  
      Further, the present invention also provides a communication terminal device, which performs peer-to-peer communication by a first communication system with a first communication terminal device performing peer-to-peer communication by the first communication system, and which performs communication via a communication network by a second communication system, including:  
      an application receiving section which receives a communication relay application by the first communication system from the first communication terminal device;  
      a relay communication section which performs, in response to receipt of an application by the application receiving section, communication corresponding to the application via the communication network by the second communication system; and  
      a relay result transmitting section which transmits by the first communication system the result of communication by the relay communication section to the first communication terminal device.  
      With this communication terminal device according to the present invention, it is possible to receive the relay application from the first communication terminal device, to perform communication via the communication network, and to transmit the communication result to the first communication terminal device.  
      According to the present invention, various functions and services can be utilized by using a familiar communication terminal device which are usually used. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a schematic illustration of an example of a communication system to which an embodiment according to the present invention is applied;  
       FIG. 2  is an external perspective illustration of a portable telephone;  
       FIG. 3  is a figure showing a hardware configuration of the portable telephone;  
       FIG. 4  is a figure showing functional blocks which are constituted in a low function terminal device, a high function terminal device and a base station, and which are necessary for realizing a function (relay function) characteristic of the present embodiment;  
       FIG. 5  is a flow chart showing an example of process flow in the relay function;  
       FIG. 6  is a flow chart showing a series of data flow in the search processing shown in step S 20  in  FIG. 5 ;  
       FIG. 7  is a flow chart showing a series of data flow in the relay application processing shown in step S 30  in  FIG. 5 ;  
       FIG. 8  is a flow chart showing a series of data flow in the case where the communication application processing shown in step S 40  in  FIG. 5  is performed by the low function terminal device;  
       FIG. 9  is a flow chart showing a series of data flow in the case where the communication application processing shown in step S 40  in  FIG. 5  is performed by the high function terminal device;  
       FIG. 10  is a flow chart showing a series of data flow in data relay processing by the high function terminal device;  
       FIG. 11  is a flow chart showing a series of data flow in the case where the data relay stop instruction shown in step S 70  in  FIG. 5  is transmitted from the low function terminal device;  
       FIG. 12  is a flow chart showing a series of data flow in the case where the data relay stop instruction shown in step S 70  in  FIG. 5  is transmitted from the high function terminal device;  
       FIG. 13  is a flow chart showing a series of data flow in the case where the data relay stop instruction shown in step S 70  in  FIG. 5  is transmitted from the base station; and  
       FIG. 14  is a flow chart showing a series of data flow in the handover processing shown in step S 100  in  FIG. 5 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      In the following, the present invention is described with reference to the accompanying drawings.  
       FIG. 1  is a schematic illustration of an example of a communication system to which an embodiment according to the present invention is applied.  
      In  FIG. 1 , there are shown portable telephones  10 ,  20 A,  20 B and a base station  30  by way of which radio communication is performed between portable telephones  10 ,  20 A,  20 B. Noted that in practice, a number of portable telephones are connected with the base station  30 , and further a number of base stations, the Internet line and the like are connected with each other, but for the sake of simplicity, only those necessary for explaining the present invention are shown in  FIG. 1 .  
      Portable telephones  10 ,  20 A,  20 B, each has a network communication section which communicates via the base station  30 , and a common communication section which directly performs communication between the portable telephones  10 ,  20 A,  20 B by using infrared radiation. Further, in the network communication section provided for the portable telephones  20 A,  20 B, there is incorporated a high function communication system which performs high-speed transmission and reception of data compressed by a high compression system to and from the base station, while in the network communication section provided for the portable telephones  10 , there is incorporated a low function communication system which cannot perform transmission and reception of data compressed by the high compression system but which performs low-speed transmission and reception of data to and from the base station. For this reason, a moving image compressed by the high compression system cannot be downloaded only with the portable telephone  10 . In the following, the portable telephone  10  is referred to as a low function terminal device  10 , and the portable telephones  20 A,  20 B are referred to as high function terminal devices  20 A,  20 B, so as to make them distinguished from each other. The infrared communication system incorporated in the common communication section of the portable telephones  10 ,  20 A,  20 B corresponds to an example of the first communication system in the present invention. The high function communication system incorporated in the network communication section of the high function terminal devices  20 A,  20 B corresponds to an example of the second communication system in the present invention. The low function communication system incorporated in the network communication section of the low function terminal device  10  corresponds to the third communication system in the present invention. Further, the low function terminal device  10  corresponds to an example of the first communication terminal device in the present invention. The high function terminal devices  20 A,  20 B, each corresponds to an example of the second communication terminal device in the present invention. The base station  30  corresponds to an example of the base station in the present invention.  
      In the communication system according to the present embodiment, there is prepared a relay function which performs the downloading operation of data compressed by the high compression system between the high function terminal devices  20 A,  20 B and the base station  30 , and which transmits the downloaded data to the low function terminal device  10 . The relay function is described in detail below.  
       FIG. 2  is an external perspective illustration of a portable telephone, and  FIG. 3  is a figure showing a hardware configuration of the portable telephone. The low function terminal device  10  and the high function terminal devices  20 A,  20 B have different communication performances, but have almost the same configuration. Thus, in  FIG. 2  and  FIG. 3 , the low function terminal device  10  is described on behalf of the devices.  
      As shown in  FIG. 2 , the low function terminal device  10  consists of an upper casing  11  and a lower casing  12  which are opened/closed each other. The upper casing  11  is provided with a LCD  111  for displaying an image, and a transmitter port  112  in which a small speaker is arranged and which is brought closer to an ear to listen to sound voice.  
      The lower casing  12  is provided with various kinds of operation keys  121  which are operated by a user in order to make a phone call, to transmit an electronic mail by using the low function terminal device  10  and to perform various setting operations, a receiver port  122  in which a microphone to pick up user&#39;s voice is incorporated and which guides the voice to the microphone, a sound emission port  123  in which a slightly large speaker is incorporated and which outputs sound voice with a degree enough to be surely heard, without the port being brought closer to an ear, and a loading port  124  through which a recording medium is loaded.  
      Further, a CPU  101 , a RAM  102 , a microphone unit  103 , a speaker unit  104 , a camera unit  105 , a short distance radio unit  106 , a media controller  107 , a ROM  108 , a nonvolatile memory  109 , a display unit  110 , a key unit  113 , a clock  114 , a long distance communication unit  115  and an antenna  116  are shown in  FIG. 3 , and are connected with each other via a bus  100  except for the antenna  116 .  
      The CPU  101  has a function to perform various programs and performs overall control of the low function terminal device  10 .  
      In the ROM  108 , various programs performed by the CPU  101  and various constants necessary for executing the various programs are stored, and the CPU  101  performs the programs stored in the ROM  108  by using the RAM  102  as a work area.  
      In the nonvolatile memory  109 , various pieces of information such as an address book, a received electronic mail and the like, which may be rewritten, are recorded.  
      The microphone unit  103  is a function block which includes a microphone to pick up user&#39;s voice and which performs processing of the voice picked up by the microphone.  
      The sneaker unit  104  is a function block which includes a speaker to output voice sound to the user and which generates sound signals to drive the speaker.  
      The short distance radio unit  106  is provided to transmit an image, a telephone number and the like to an external device at a short distance without the intervention of the base station, and the infrared communication is employed in the present embodiment.  
      The camera unit  105  is a block which collects image data obtained by shooting. The display unit  110  is a block which displays the image on the LCD  111  (see  FIG. 2 ). The key unit  113  is a block which detects a key operation of the various operation keys  121  (see  FIG. 2 ) by the user. The clock  114  is a block to acquire the present time.  
      The media controller  107  is provided to read data from a recording medium  200  loaded into the loading port  124  shown in  FIG. 2 , or writing image data generated by the camera unit  105  in the recording medium  200 .  
      The long distance communication unit  115  has the role of transmitting and receiving voice sound data, an electronic mail and the like via the antenna  116 .  
      The low function terminal device  10  and the high function terminal devices  20 A,  20 B are constituted as described above with respect to external appearance and hardware.  
       FIG. 4  is a figure showing function blocks which are constituted in the low function terminal device  10 , the high function terminal devices  20 A,  20 B and the base station  30 , shown in  FIG. 1 , and which are necessary for realizing a function (relay function) characteristic of the present embodiment.  
      The base station  30  is provided with a network communication section  32  which communicates with the low function terminal device  10  and the high function terminal devices  20 A,  20 B, and a communication control section  31  which controls the base station  30  and the whole communication system.  
      The high function terminal devices  20 A,  20 B, each is provided with: a network communication section  21  whose role is played by the long distance communication unit  115  of the high function terminal devices  20 A,  20 B (see  FIG. 3 ), and which performs radio communication by the high function communication system via the base station  30 ; a common communication section  22  whose role is played by the short distance radio unit  106  of the high function terminal devices  20 A,  20 B (see  FIG. 3 ), and which performs peer-to-peer communication with an external device by using infrared radiation; a relay control section  23  which controls the high function terminal devices  20 A,  20 B; and a storage section  24  which stores various information about communication. Further, the common communication section  22  is constituted by a request/response section  222  which receives a request transmitted from the low function terminal device  10  and which transmits a response to the request to the low function terminal device  10 , and a routing section  221  which transfers data received by the network communication section  21  to the low function terminal device  10  and which transmits data sent from the low function terminal device  10  to the network communication section  21 . The request/response section  222  corresponds to an example of the application receiving section in the present invention. The network communication section  21  corresponds to an example of the relay communication section in the present invention. The routing section  221  corresponds to the relay result transmitting section in the present invention.  
      The low function terminal device  10  is provided with a network communication section  310  whose role is played by the long distance communication unit  115  of the low function terminal device  10  (see  FIG. 3 ), and which performs radio communication by the low function communication system via the base station  30 , a common communication section  320  whose role is played by the short distance radio unit  106  of the low function terminal device  10  (see  FIG. 3 ), and which performs peer-to-peer communication with an external device by using infrared radiation, a relay control section  330  which controls the low function terminal device  10  as a whole, a storage section  340  which stores various information about communication, and a search section  350  which searches the high function terminal device. Further, the common communication section  320  is constituted by a request/response section  322  which transmits various requests to the external device and receives responses to the requests, and a user data transmitting/receiving section  321  which receives data sent from the high function terminal devices  20 A,  20 B by the relay function, and which transmits to the high function terminal devices  20 A,  20 B data to be transferred to the external device. The search section  350  corresponds to an example of the first search section in the present invention. The request/response section  322  corresponds to an example of the relay application section in the present invention. The user data transmitting/receiving section  321  corresponds to an example of the relay result receiving section in the present invention.  
      The communication system is fundamentally constituted as described above.  
      Subsequently, the relay function performed by the communication system shown in  FIG. 4  will be described.  
       FIG. 5  is a flow chart showing an example of process flow in the relay function.  
      As described above, in the low function communication system employed in the network communication section  310  of the low function terminal device  10 , data compressed by the high compression system cannot be transmitted and received. Thus, downloading of a moving image and the like cannot be performed by the low function terminal device  10  alone. When downloading the moving image by using the low function terminal device  10 , the user of the low function terminal device  10  pushes the operation key  121  shown in  FIG. 2 , and selects the start of the relay function. At this time, contents of the operation of the operation key  121  are transmitted to the relay control section  330  in  FIG. 4  via the key unit  113  in  FIG. 3 , and an instruction to start the relay communication is transmitted to each section of the low function terminal device  10  from the relay control section  330  (step S 10  in  FIG. 5 ). When the start of relay communication is instructed, search processing is started in the low function terminal device  10  (step S 20  in  FIG. 5 ).  
       FIG. 6  is a flow chart showing a series of data flow in the search processing shown in step S 20  in  FIG. 5 .  
      When the search processing is started, a search request which requires a response as to whether functions necessary for the relay communication to be performed are loaded or not, is generated in the search section  350  of the low function terminal device  10 . The present embodiment is described as making a request as to whether “the function of transmitting and receiving data compressed by the high compression system” is loaded or not. In the request/response section  322 , the search request generated in the search section  350  is transmitted by peer-to-peer communication using infrared radiation (step S 21  in  FIG. 6 ).  
      In the high function terminal device  20 A within the infrared radiation area where the infrared radiation transmitted from the low function terminal device  10  can be received, the search request transmitted from the low function terminal device  10  is received in the request/response section  222  of the common communication section  22 . The received search request is transmitted to the relay control section  23  (step S 22  in  FIG. 6 ). In the relay control section  23 , whether the function required by the search request is loaded into the high function terminal device  20 A or not is determined, so that the determination result and the identification information which identifies the terminal device  20 A itself, are transmitted as a search response to the request/response section  222  (step S 23  in  FIG. 6 ). In present embodiment, the high function terminal device  20 A is determined to be loaded with “the function of transmitting and receiving data compressed by the high compression system”, so that the determination result and the telephone number uniquely assigned to the high function terminal device  20 A are transmitted as the search response. In the request/response section  222 , the search response received from the relay control section  23  is transmitted by peer-to-peer communication using infrared radiation (step S 24  in  FIG. 6 ).  
      In the low function terminal device  10 , the search response is received in the request/response section  322 , and the received search response is transmitted to the search section  350  (step S 25  in  FIG. 6 ). In the search section  350 , the determination result and the identification information which are contained in the search response are confirmed, so that the identification information of the terminal device  20 A determined to be loaded with the requested function is transmitted to the relay control section  330 , and the identification information of the terminal device  20 A is stored as the search result in the storage section  340  (step S 26  in  FIG. 6 ). By storing the search result, it is only necessary from the next time to search whether or not the high function terminal device  20 A exists in the infrared area of the low function terminal device  10 . Thereby, it is possible to eliminate the time necessary for the low function terminal device  10  to confirm the function loaded to the high function terminal device  20 A, and to search responses transmitted from plural terminal devices one by one.  
      The search processing shown in step S 20  in  FIG. 5  is performed as described above. When no high function terminal device is found within the infrared area range of the low function terminal device  10  as a result of the search processing, a message that “no terminal device corresponding to the request exists” is displayed on the LCD  111  of the low function terminal device  10 , and then the relay function is stopped. When a high function terminal device is found within the infrared area range, the identification information (the telephone number in the present embodiment) of the found high function terminal device is displayed on the LCD  111  of the low function terminal device  10 . When plural high function terminal devices are found, one of the plural high function terminal devices is selected by the user.  
      When a high function terminal device  20 A is determined, the relay application processing which applies for execution of the relay function to the high function terminal device  20 A, is started (step S 30  in  FIG. 5 ).  
       FIG. 7  is a flow chart showing a series of data flow in the relay application processing shown in step S 30  in  FIG. 5 .  
      In the relay control section  330  of the low function terminal device  10 , a relay request which includes the identification information (the telephone number in the present embodiment) of the low function terminal device  10  and which requests to execute the relay function is generated, and the generated relay request is transmitted to the request/response section  322 . In the request/response section  322 , the relay request is transmitted to the high function terminal device  20 A by peer-to-peer communication using infrared radiation (step S 31  in  FIG. 7 ).  
      In the high function terminal device  20 A, the relay request transmitted from the low function terminal device  10  is received by the request/response section  222  of the common communication section  22 . The received relay request is transmitted to the relay control section  23  (step S 32  in  FIG. 7 ).  
      Here, the high function terminal device  20 A is loaded with the communication function based on the high function communication system, but, for example, there are cases where execution of the relay function is permitted to only a telephone number predetermined by the user, and where no contract to utilize the service of communication by the high function communication system is made with the base station  30 . In the relay control section  23 , authentication of the low function terminal device  10  is performed on the basis of the identification information contained in the relay request, and further whether execution of the relay function in the high function terminal device  20 A is permitted or not, is determined on the basis of the presence or absence of permission given by the user, and of the communication contract between the high function terminal device  20 A and the base station  30 , and the like. The determination result and the communication information (for example, IP address of the high function terminal device  20 A and the like) necessary for performing communication with the base station  30  are transmitted as a relay response to the request/response section  222  (step S 33  in  FIG. 7 ). The present embodiment is described as making the relay function permitted to be performed in the high function terminal device  20 A. The relay response received by the request/response section  222  is transmitted to the low function terminal device  10  by peer-to-peer communication using infrared radiation (step S 34  in  FIG. 7 ).  
      In the low function terminal device  10 , the relay response is received in the request/response section  322 , and the communication information contained in the relay response is stored as the relay information in the storage section  340  (step S 35  in  FIG. 7 ). By storing the relay information, it is possible to simplify the relay application processing from the next time, and to make the whole processing performed at a high speed.  
      As described above, the relay application processing shown in step S 30  in  FIG. 5  is executed. When execution of the relay function is not permitted by the high function terminal device  20 A as a result of the relay application processing, the message of “no relay permission” is displayed on the LCD  111  of the low function terminal device  10 , and the relay function is stopped.  
      When execution of the relay function is permitted, the communication application processing which requires the start of communication is started for the base station  30  (step S 40  in  FIG. 5 ).  
      The communication application processing shown in step S 40  in  FIG. 5  includes the case where the communication application is made from the low function terminal device  10  to the base station  30 , and the case where the communication application is made from the high function terminal device  20 A to the base station  30 . First, the case where the communication application is made from the low function terminal device  10  is described.  
       FIG. 8  is a flow chart showing a series of data flow in the case where the communication application processing shown in step S 40  in  FIG. 5  is performed by the low function terminal device  10 .  
      When the communication application processing is started, in the low function terminal device  10 , a call connection communication request consisting of the IP address of the low function terminal device  10 , the IP address of the high function terminal device  20 A and the like, are generated in the relay control section  330 , and the generated call connection communication request is transmitted to the network communication section  310 . The network communication section  310  transmits the call connection communication request to the base station  30 . Unlike the low function communication system and the high function communication system, the call connection communication is a simple communication for request/response in which a simple communication procedure is employed.  
      In the base station  30 , the call connection communication request is received in the network communication section  32 . The network communication section  32  establishes call connection communication between the low function terminal device  10  and the high function terminal device  20 A on the basis of the IP address of the low function terminal device  10  and the IP address of the high function terminal device  20 A, which are included in the call connection communication request (step S 411  in  FIG. 8 ). Further, the communication control section  31  determines whether execution of the relay function is permitted or not, on the basis of whether the communication quality between the base station  30  and the high function terminal device  20 A can be ensured or not, and the like, and transmits the determination result as a communication permission response to the network communication section  32  (step S 412  in  FIG. 8 ). The present embodiment is described as making execution of the relay function permitted. The communication permission response received by the network communication section  32  is transmitted to the low function terminal device  10  and the high function terminal device  20 A (steps S 413 , S 415  in  FIG. 8 ).  
      In the low function terminal device  10 , the communication permission response is received in the network communication section  310 , and the received communication permission response is stored as the communication information in the storage section  340  (step S 414  in  FIG. 8 ).  
      Further, in the which function terminal device  20 A, the communication permission response is also received in the network communication section  21 . Upon receipt of the communication permission response sent from the base station  30 , the network communication section  21  transmits to the base station  30  a communication request which requires the start of communication by the high function communication system.  
      Upon receipt of the communication request sent from the high function terminal device  20 A, the network communication section  32  in the base station  30  establishes communication with the high function communication terminal device  20 A by the high function communication system, and transmits a permission response of high function communication to the high function communication terminal device  20 A (step S 416  in  FIG. 8 ).  
      In the high function terminal device  20 A, the permission response of high function communication is received in the network communication section  21 , and the received permission response is stored as the communication information in the storage section  24  (step S 417  in  FIG. 8 ).  
      As shown in step S 414  and step S 417  in  FIG. 8 , by storing the communication information, it is possible to simplify the communication establishment processing and to make the processing performed at a high speed from the next time.  
      In this way, the call connection communication between the low function terminal device  10  and the base station  30  is established by making the communication application from the low function terminal device  10  to the base station  30 , so that a request can be directly transmitted from the base station  30  to the low function terminal device  10 .  
      Further, in the case where the low function terminal device  10  is not provided with the function of communication via the network performed by the network communication section  310 , and the like, the communication application is transmitted via the high function terminal device  20 A.  
       FIG. 9  is a flow chart showing a series of data flow in the case where the communication application processing shown in step S 40  in  FIG. 5  is performed by the high function terminal device.  
      When the communication application processing is started, in the low function terminal device  10 , the communication application request is transmitted from the relay control section  330  to the request/response section  322 , and the communication application request is transmitted from the request/response section  322  to the high function terminal device  20 A (step S 421  in  FIG. 9 ).  
      In the high function terminal device  20 A, the communication application request is received by the request/response section  222 , and the call connection communication request consisting of the IP address of the high function terminal device  20 A and the like is transmitted to the network communication section  21  (step S 422  in  FIG. 9 ). The call connection communication request transmitted to the network communication section  21  is further transmitted to the base station  30 .  
      In the network communication section  32  of the base station  30 , when the call connection communication request is received, the call connection communication with the high function terminal device  20 A is established on the basis of the IP address of the high function terminal device  20 A included in the call connection communication request (step S 423  in  FIG. 9 ). Further, in the communication control section  31 , whether execution of the relay function is permitted or not is determined, and the determination result is transmitted as a communication permission response to the network communication section  32  (step S 424  in  FIG. 9 ). The communication permission response received by the network communication section  32  is transmitted to the high function terminal device  20 A (step S 425  in  FIG. 9 ).  
      In the high function terminal device  20 A, the communication permission response is received by the network communication section  21 , and a communication request which requires the start of communication by the high function communication system is transmitted from the network communication section  21  to the base station  30 .  
      The network communication section  32  of the base station  30  establishes communication by the high function communication system with the high function communication terminal device  20 A in response to the communication request, and transmits a permission response of high function communication to the high function communication terminal device  20 A (step S 426  in  FIG. 9 ).  
      In the high function terminal device  20 A, the permission response of high function communication is received by the network communication section  21 , and the received permission response is stored as the communication information in the storage section  24  (step S 427  in  FIG. 9 ). Further, the communication permission response to the communication application request received in step S 421  is transmitted from the request/response section  222  to the low function terminal device  10  (step S 428  in  FIG. 9 ).  
      The communication permission response is received by the request/response section  322  of the low function terminal device  10 , and the communication permission response is stored as the communication information in the storage section  340  (step S 429  in  FIG. 9 ).  
      As described above, the communication application processing shown in step S 40  in  FIG. 5  is performed. When execution of the relay function is not permitted by the base station  30  as a result of the communication application processing, the message of “no relay permission” is displayed on the LCD  111  of the low function terminal device  10 , and the relay function is stopped.  
      When execution of the relay function is permitted by the base station  30  and communication between the high function terminal device  20 A and the base station  30  is established (step S 50  in  FIG. 5 ), data transmitted and received by the low function terminal device  10  are started to be relayed by the high function terminal device  20 A (step S 61  in  FIG. 5 ), and transmission and reception of data are performed between the high function terminal device  20 A and the base station  30  (step S 62  in  FIG. 5 ).  
       FIG. 10  is a flow chart showing a series of data flow in data relay processing by the high function terminal device  20 A.  
      When data is transmitted from the low function terminal device  10  by using the relay function, communication data generated by the user&#39;s operation of the operation key  121  are transmitted from the user data transmitting/receiving section  321  to the high function terminal device  20 A (step S 601  in  FIG. 10 ), and the transmitted communication data are received by the routing section  221  of the high function terminal device  20 A. In this way, the transmission and reception of data between the low function terminal device  10  and the high function terminal device  20 A are performed by infrared communication without the intervention of the network.  
      The communication data received by the routing section  221  are transmitted to the network communication section  21  (step S 602  in  FIG. 10 ), and the high function communication system is employed so that the received communication data are transmitted from the network communication section  21  to the base station  30  (step S 603  in  FIG. 10 ). In the base station  30 , the communication data are received by the network communication section  32 . In this way, transmission and reception of the data between the high function terminal device  20 A and the base station  30  are performed via the network by employing the high function communication system.  
      When data are received by the low function terminal device  10  by using the relay function, the high function communication system is employed so that communication data are transmitted from the network communication section  32  of the base station  30  to the high function terminal device  20 A (step S 604  in  FIG. 10 ), and the transmitted communication data are received by the network communication section  21  of the high function terminal device  20 A. The received communication data are transmitted to the routing section  221  (step S 605  in  FIG. 10 ), and are transmitted by infrared communication from the routing section  221  to the low function terminal device  10  (step S 606  in  FIG. 10 ).  
      In the low function terminal device  10 , the communication data transmitted from the high function terminal device  20 A are received by the user data transmitting/receiving section  321 .  
      In this way, according to the present embodiment, the high function communication system  20 A performs communication by the high function communication system and transfers the communication result to the low function terminal device  10  by infrared communication, thereby enabling even the low function terminal device  10  which is not provided with the high function communication system, to obtain moving image data and the like which cannot be obtained without the use of the high function communication system.  
      While data relay processing is performed by the high function terminal device  20 A, for example, when the high function terminal device  20 A is moved outside the infrared area range of the low function terminal device  10 , and the like, the data relay stop processing is performed (step S 70  in  FIG. 5 ). The data relay stop processing includes the case where a stop instruction is transmitted from the low function terminal device  10 , and the case where a stop instruction is transmitted from the high function terminal device  20 A. First, the case where the stop instruction is transmitted from the low function terminal device  10  is described.  
       FIG. 11  is a flow chart showing a series of data flow in the case where the data relay stop instruction shown in step S 70  in  FIG. 5  is transmitted from the low function terminal device.  
      In the comparison between communication charges utilizing the low function communication system and that utilizing the high function communication system, the communication charge utilizing the high function communication system is generally more expensive. For example, in the case where the inexpensive low function communication system is selected even though the communication speed is deteriorated, the user of the low function terminal device  10  instructs to perform switching from communication utilizing the relay function to communication by the low function communication system by using the operation key  121  of the low function terminal device  10 . At this time, the contents instructed by the user are transmitted to the relay control section  330  via the key unit  113 . In the relay control section  330 , a relay function stop request is generated, and the generated relay function stop request is transmitted to the request/response section  322  (step S 701  in  FIG. 11 ). The relay stop request received by the request/response section  322  is transmitted to the high function terminal device  20 A (step S 702  in  FIG. 11 ). A combination of the operation key  121 , the key unit  113  and the relay control section  330 , for switching between communication utilizing the relay function and communication by the low function communication system, corresponds to an example of the first switching section in the present invention, while the relay control section  330  which instructs to stop the relay function corresponds to an example of the second switching section in the present invention.  
      In the high function terminal device  20 A, the relay stop request is received by the request/response section  222 , and the received stop request is transmitted to the relay control section  23  (step S 703  in  FIG. 11 ). The relay control section  23  instructs the network communication section  21  to stop the relay communication, and generates a communication stop request requiring the stop of communication between the high function terminal device  20 A and the base station  30 , and transmits the generated communication stop request to the network communication section  21  (step S 704  in  FIG. 11 ). The network communication section  21  transmits the communication stop request to the base station  30  (step S 705  in  FIG. 11 ).  
      The communication stop request transmitted from the high function terminal device  20 A is received by the network communication section  32  of the base station  30 , and transmitted to the communication control section  31  (step S 706  in  FIG. 11 ). The communication control section  31  instructs the network communication section  32  to disconnect the network with the high function terminal device  20 A, and transmits permission to stop communication to the network communication section  32  (step S 707  in  FIG. 11 ). The network communication section  32  transmits communication stop permission to the high function terminal device  20 A (step S 708  in  FIG. 11 ), and disconnects the network with the high function terminal device  20 A.  
      In the high function terminal device  20 A, when the communication stop permission is received by the network communication section  21 , the communication stop permission is transmitted to the relay control section  23  (step S 709  in  FIG. 11 ). The relay control section  23  transmits the communication stopper mission to the request/response section  222 , and makes the network communication section  21  perform processing to disconnect the network with the base stations  30 . The request/response section  222  transmits the communication stop permission to the low function terminal device  10  (step S 711  in  FIG. 11 ).  
      In the low function terminal device  10 , the communication stop permission received by the request response section  322  is transmitted to the relay control section  330  (step S 712  in  FIG. 11 ). The relay control section  330  generates a communication request requiring the start of communication by the low function communication system, and transmits the communication request to the network communication section  310  (step S 713  in  FIG. 11 ). The network communication section  310  transmits the communication request to the base station  30 . As a result, the communication by the low function communication system is established between the base station  30  and the low function terminal device  10  (step S 714  in  FIG. 11 ).  
      As described above, according to the present embodiment, the communication mode as to whether the relay function is utilized, or communication by the low function communication system loaded to the low function terminal device  10  is performed, can be switched by the user of the low function terminal device  10 , depending upon the communication condition, data size to be downloaded and the like.  
      Subsequently, the case where the data relay stop instruction is transmitted from the high function terminal device  20 A is described.  
       FIG. 12  is a flow chart showing a series of data flow in the case where the data relay stop instruction shown in step S 70  in  FIG. 5  is transmitted from the high function terminal device  20 A.  
      For example, while the high function terminal device  20 A performs the relay communication, when the user of the high function terminal device  20 A is going to utilize communication by the high function communication system, the relay communication is stopped because the communication speed is deteriorated. While the relay communication is performed, when the user of the high function terminal device  20 A instructs downloading of data and the like by using the operation key  121  of the high function terminal device  20 A, the contents of the user&#39;s instruction are transmitted to the relay control section  23  via the key unit  113  of the high function terminal device  20 A. In the relay control section  23 , a relay function stop request and a communication stop request are generated, so that the relay function stop request is transmitted to the request/response section  222  (step S 721  in  FIG. 12 ), and the communication stop request is transmitted to the network communication section  21  (step S 727  in  FIG. 12 ). The relay function stop request received by the request/response section  222  is transmitted to the low function terminal device  10  (step S 723  in  FIG. 12 ), and the communication stop request transmitted to the network communication section  21  is further transmitted to the base station  30  (step S 728  in  FIG. 12 ). The relay control section  23  which instructs the stop of the relay function also corresponds to an example of the second switching section in the present invention.  
      In the base station  30 , the communication stop request received by the network communication section  32  is transmitted to the communication control section  31  (step S 729  in  FIG. 12 ). The communication control section  31  instructs the network communication section  32  to disconnect the network with the high function terminal device  20 A, and transmits communication stop permission to the network communication section  32  (step S 730  in  FIG. 12 ). The network communication section  32  transmits the communication stop permission to the high function terminal device  20 A (step S 731  in  FIG. 12 ), and disconnects the network with the high function terminal device  20 A.  
      Further, in the low function terminal device  10 , the relay function stop request received by the request/response section  322  (step S 722  in  FIG. 12 ) is transmitted to the relay control section  330  (step S 723  in  FIG. 12 ). In the relay control section  330 , relay stop permission for permitting the stop of relay function is transmitted to the request/response section  322 , and the relay stop permission is transmitted from the request/response section  322  (step S 724  in  FIG. 12 ) to the high function terminal device  20 A (step S 725  in  FIG. 12 ).  
      In the high function terminal device  20 A, the communication stop permission received by the request/response section  222  is transmitted to the relay control section  23  (step S 726  in  FIG. 12 ), and the communication stop permission received by the network communication section  21  is also transmitted to the relay control section  23  (step S 732  in  FIG. 12 ), as a result of which the relay communication is stopped.  
      Further, in the low function terminal device  10 , a communication request which requires the start of communication by the low function communication system is generated in the relay control section  330 , and transmitted to the network communication section  310  (step S 733  in  FIG. 12 ). When the network communication section  310  transmits the communication request to the base station  30 , the communication by the low function communication system is established between the base station  30  and the low function terminal device  10  (step S 734  in  FIG. 12 ).  
      Subsequently, the case where the data relay stop instruction is transmitted from the base station  30  is described.  
       FIG. 13  is a flow chart showing a series of data flow in the case where the data relay stop instruction shown in step S 70  in  FIG. 5  is transmitted from the base station  30 .  
      For example, at the time when the network is crowded, and the like, the communication performance between the high function terminal device  20 A and the base station  30  may not be guaranteed. In such a case, the communication stop request is transmitted from the communication control section  31  of the base station  30  to the network communication section  32  (step S 740  in  FIG. 13 ), and the communication stop request is transmitted from the network communication section  32  to the high function terminal device  20 A (step S 742  in  FIG. 13 ). The communication control section  31  which instructs the stop of relay function, also corresponds to an example of the second switching section in the present invention.  
      In the high function terminal device  20 A, the communication stop request received by the network communication section  21  is transmitted to the relay control section  23  (step S 743  in  FIG. 13 ). In response to the received request, in the relay control section  23 , a relay communication stop request is transmitted to the request/response section  222  (step S 744  in  FIG. 13 ), and the relay communication stop request is transmitted from the request/response section  222  to the low function terminal device  10  (step S 745  in  FIG. 13 ).  
      In the low function terminal device  10 , the relay function stop request received by the request/response section  322  is transmitted to the relay control section  330  (step S 746  in  FIG. 13 ). In the relay control section  330 , upon receipt of the relay function stop request, relay stop permission is transmitted to the request/response section  322  (step S 747  in  FIG. 13 ), and the relay stop permission is transmitted from the request/response section  322  to the high function terminal device  20 A (step S 748  in  FIG. 13 ).  
      In the high function terminal device  20 A, the relay stop permission received by the request/response section  222  is transmitted to the relay control section  23  (step S 749  in  FIG. 13 ), and upon receipt of the relay stop permission, communication stop permission is transmitted from the relay control section  23  to the network communication section  21  (step S 750  in  FIG. 13 ), so that the communication stop permission is transmitted from the network communication section  21  to the base station  30  (step S 751  in  FIG. 13 ).  
      In the base station  30 , the communication stop permission received by the network communication section  32  is transmitted to the communication control section  31  (step S 752  in  FIG. 13 ). The communication control section  31  instructs the network communication section  32  to disconnect the network with the high function terminal device  20 A, and the network communication section  32  disconnects the network with the high function terminal device  20 A.  
      Further, in the low function terminal device  10 , a communication request which requires the start of communication by the low function communication system is generated in the relay control section  330 , and the communication request is transmitted to the network communication section  310  (step S 753  in  FIG. 13 ). When the network communication section  310  transmits the communication request to the base station  30 , the communication by the low function communication system is established between the base station  30  and the low function terminal device  10  (step S 754  in  FIG. 13 ).  
      As described above, the relay communication by the high function terminal device  20 A is stopped (step S 70  in  FIG. 5 ), and the switching to the communication by the low function communication system is effected between the low function terminal device  10  and the base station  30 . Further, when restart of the relay function is instructed by the user of the low function terminal device  10 , the relay communication by the high function terminal device  20 A is resumed by the same procedures as step S 40  and step S 50  in  FIG. 5  (step S 80 , step S 90  in  FIG. 5 ), and the communication between the low function terminal device  10  and the base station  30  is vicariously performed by the high function terminal device  20 A.  
      Further, while the relay communication is performed by the high function terminal device  20 A, when the high function terminal device  20 A is likely to move to the outside of the infrared area range of the low function terminal device  10 , hand-over processing is performed (step S 100  in  FIG. 5 ).  
       FIG. 14  is a flow chart showing a series of data flow in the handover processing in step S 100  shown in  FIG. 5 .  
      While the communication between the low function terminal device  10  and the base station  30  is relayed by the high function terminal device  20 A, when the high function terminal device  20 A is moved to the outside of the secured infrared area range where the infrared radiation emitted by the low function terminal device  10  can be surely received, the search processing of step S 20  in  FIG. 5  is performed to search a terminal device which exists in the infrared area range of the low function terminal device  10 , and which has “the function of transmitting and receiving data compressed by the high compression system”. When the high function terminal device  20 B is found, the relay application processing of step S 30  in  FIG. 5  is performed, and a relay request is transmitted from the low function terminal device  10  to the high function terminal device  20 B (step S 101  in  FIG. 14 ).  
      In the high function terminal device  20 B, whether execution of the relay function is permitted or not is determined in response to the relay request transmitted from the low function terminal device  10 . When execution of the relay function is determined as being permitted, the relay request is transmitted to the base station  30  (step S 102  in  FIG. 14 ).  
      Also in the base station  30 , whether execution of the relay function is permitted or not is determined in response to the relay request transmitted from the high function terminal device  20 B. When execution of the relay function is determined as being permitted relay permission is transmitted to the high function terminal device  20 B and the low function terminal device  10  (step S 103 , step S 104  in  FIG. 14 ).  
      In the low function terminal device  10 , a relay stop request is transmitted to the high function terminal device  20 A (step S 105  in  FIG. 14 ), and in the high function terminal device  20 A, relay stop permission is transmitted to the low function terminal device  10  in response to the relay stop request (step S 106  in  FIG. 14 ), as a result of which the communication with the base stations  30  is disconnected (step S 107  in  FIG. 14 ).  
      Further, communication by the high function communication system is established between the base station  30  and the high function terminal device  20 B, (step S 108  in  FIG. 14 ), and communication between the low function terminal device  10  and the base station  30  is relayed by the high function terminal device  20 B (step S 109  in  FIG. 14 ).  
      In this way, after a new high function terminal device is searched and found, the relay of communication is switched to the new high function terminal device, so that the relay processing can be continued without interrupting the communication between the low function terminal device  10  and the base station  30 .  
      As described above, according to the present embodiment, for example when a high function terminal device with an overseas communication function exists in the vicinity of the low function terminal device which does not have the overseas communication function, the high function terminal device vicariously performs the network communication and transmits the communication result to the low function terminal device with infrared radiation and the like, thereby enabling communication to be performed by using the low function terminal device, even aboard.  
      In the above description, an example in which a portable telephone is applied as a communication terminal device according to the present invention is used. However, the PDA and the Internet telephone which performs speech communication by using the Internet line may also be applied as the communication terminal device in the present invention.  
      In the above description, an example in which infrared communication as the first communication system according to the present invention is used. However, the Bluetooth, the wire line communication by USB and the like may also be applied as the first communication system in the present invention.