JPH08140143A - Mobile videophone system - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a mobile videophone system capable of sharing a mobile phone and a videophone. [Structure] Different slots in a frame of a frequency channel are used for audio data and image data for communication by means of communication between a base station and a video telephone, and the number of image data slots is variable depending on the data amount. The voice data of the two mobile phones is assigned to the frequency channel that is using the slot (a), and a new video telephone is added to assign the slot for voice data and the slot for image data (b). Furthermore, the number of image data slots is increased to improve image quality (c). In addition, it is possible to communicate with the mobile phone using only the voice data slot.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile videophone system.

[0002]

2. Description of the Related Art Ultra-compact and lightweight mobile phones have become popular in Japan since 1991, and digital mobile phone services started in 1993, and at the same time, charges became more affordable. In particular, digital type mobile phones are easy to use for data transfer other than voice, and are being tried for data communication with facsimiles and personal computers. Further, as the development of these technologies, various personal-use information terminals or multimedia terminals have been proposed. The most promising of these information terminals is an image, which is a portable videophone, but has not been put to practical use. Although a videophone system using a wired line has been put into practical use, it costs a lot of money because it occupies multiple phone lines, and it is intended for corporate corporations such as videoconferencing systems. Absent.

[0003]

However, in the conventional mobile phone system, it takes a long time to transmit a moving image having a large amount of information, and when it is used for a video phone for conversation in real time, a time delay becomes long. It means that normal conversations are difficult or impossible with videophones.

Further, in the conventional video telephone, the image transmission rate is fixed and a line having the predicted maximum image transmission rate is secured. However, in the case of image data, the amount of information varies greatly depending on the image to be transmitted, and the image is still. When used in a state close to the picture, the line usage rate decreases, resulting in a high burden on the user and hindering the spread of videophones.

In addition, the conventional system using a video telephone requires the use and facilities for business purposes such as a video conference system, and cannot be used by individuals or ordinary households.

Further, the conventional videophone system and mobile phone system have a problem that they cannot access each other and their use range is limited.

The present invention solves the above-mentioned problems of the prior art, and provides a mobile videophone system in which a mobile phone and a videophone can be shared and the image transmission rate can be varied as necessary. With the goal.

[0008]

In order to achieve this object, the present invention provides a base station capable of communicating with a plurality of mobile stations, the mobile station capable of voice and image communication, and the base station. In a mobile videophone system having a communication means using a digital modulation method of a phase shift keying method and a communication method of the mobile station is a time division multiplexing method, a time division multiplexing frame used for communication of voice data by the communication means. Slot is different from the slot in the time division multiplexing frame used for image data communication.

Further, communication of voice data is performed using one slot for each frame, and communication of image data is performed using at least one slot for each frame, and the number of slots used for image data is the amount of data. The feature is that it can be changed by.

The voice data communication is performed using one slot position determined for each frame, and the image data communication is performed using at least one slot position determined for each frame. The feature is that the number of slots used by the image data can be changed depending on the data amount.

Further, when the communication means communicates between the base station and the mobile station, the frequency channel designated by the base station is the frequency with the smallest number of slots used for communication of other mobile stations and mobile phones. It is characterized by using channels.

Further, in the frequency channel in which the communication means communicates between the base station and the mobile station, the slot of the voice data of the mobile phone using the frequency channel is the slot of the frequency channel other than the frequency channel. It is characterized by having a function capable of shifting to a conversation without interruption.

Further, when the communication means communicates between the base station and the mobile station, the communication is automatically started at the lowest image transmission rate in which one slot is allocated to voice data and one slot is allocated to image data. It is characterized by having a function of changing the transmission rate by changing the number of slots of the image data to be charged for the communication line fee according to the user's request.

Further, the line usage fee used for voice telephone communication, video telephone communication and other non-telephone data communication when the communication means communicates between the base station and the mobile station is used in the slot used for communication. In the charge system proportional to the cumulative number of slots, the charge or a numerical value equivalent to the charge is configured to be displayed on the mobile station.

[0015]

According to the above construction, the slots in the time division multiplexed frames used for the communication of the audio data and the image data are different, and the audio data used for the videophone communication has one slot position determined for each frame. Further, the image data uses at least one slot position determined for each frame, and the number of slots used for the image data can be changed depending on the data amount. Communication is possible and the image quality can be selected by changing the number of slots depending on the purpose.

Further, when performing videophone communication, the frequency channel specified by the base station is the frequency channel with the smallest number of slots used for communication of other videophones or mobile phones, and thus the image data of the image data is obtained. You can change the number of slots.

Further, in the frequency channel in which the video telephone communication is performed, the conversation of the voice data of the mobile phone using the frequency channel is interrupted to the slot of the frequency channel other than the frequency channel. It is possible to further increase the number of slots of image data by migrating to no more.

Further, when performing videophone communication, communication is automatically started at the lowest image transmission rate in which 1 slot is allocated to audio data and 1 slot to image data, and the slot of image data is requested by the user. Since the number can be changed, the line usage fee and image quality can be selected.

Further, when performing videophone communication, the line usage fee used for voice telephone communication, videophone communication and other non-telephone data communication, and a numerical value equivalent to the fee are displayed on the terminal. And economical videophone communication can be selected.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings.

First, the principle of the mobile videophone system according to the embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows each frame and slots in the time division multiplexing (TDMA) of one frequency channel, but an example will be described in which the time division multiplexing is 6 slots per frame of one frequency channel. 2 is similar to FIG. 1, but shows a case where it is requested to increase the number of slots for image data of the videophone to be equal to or more than the number of empty slots in the frame.

FIG. 1 (a) shows a case where two mobile phones use this frequency channel and the voice data of the mobile phones are communicated through each slot. The slots in each frame and the slots are used for two mobile phones, but the slots, ... Are vacant.

FIG. 1 (b) shows a frame and a slot when one video telephone is newly added to the frequency channel used by the two mobile telephones shown in FIG. 1 (a). A slot is used for audio data of the video telephone, and the slot is for image data. In this example, two slots are allocated for communication of voice data and image data of the videophone, but in the initial stage of communication, the usage mode of two slots can be automatically set. When the image of the videophone is close to a still image, it is considered that the communication of 2 slots together with the voice data and the image data is sufficient, but the image of the videophone is a moving image, and the user of the videophone can perform high-speed image data communication. The number of slots can be increased in the case of requesting, and up to 5 slots can be used for image transmission. By increasing the number of slots, the image quality of moving images improves, but as the number of occupied slots increases, the line usage fee will increase proportionally.

In the mobile videophone system, the frequency channel with the lowest number of slots used is allocated in advance so that the user of the videophone can increase the number of slots for image transmission. But if the line is busy,
As shown in FIG. 1 (b), a videophone and a mobile phone may be used in the same frame. When the videophone user requests the mobile videophone system to increase the transmission rate of the image data in such a state, as shown in FIG. Although the number of slots for data is increased, if the user of the video phone requests a further increase in the number of slots, the mobile video phone system will change the frequency channel of the slot and the mobile phone using the slot to another frequency channel. Start preparing to move to.

As shown in FIG. 1 (c), another frequency channel in which the communication slot of the mobile phone can move is searched for, and as shown in FIG. 2 (a), the slot is moved to another frequency channel, , Are opened for video data of the videophone. As a result, as shown in FIG.
A user of the videophone can use a videophone that uses 1 slot of audio data and 5 slots of image data with good image quality.

However, in the case where there is no other frequency channel to which the slot of the mobile phone already used in FIG. 1 (c) can be transferred, the number of slots for image data is the maximum slot possible in this frame. Up to three slots are used, and the number of slots is not increased until the other slots are vacant.

As another method, in response to a request for an increase in the number of slots of the videophone user, the user of the videophone does not move the already used slots to another frequency channel. Incremental slots are used for slots of other frequency channels. Figure 2 (c) shows slots for other frequency channels,
Is used as a slot for image transmission.

In the case of videophone communication using a normal videophone, voice data is transmitted using one slot like the slot shown in FIG. 1 (b). Further, since the conventional mobile phone similarly uses one slot, conversation is possible. Therefore, it becomes possible to access from the mobile phone to the video phone or from the video phone to the mobile phone. With the mobile phone, it is sufficient to take out only the voice data slot from the communication slots of the video phone. The person does not see an image on the screen if the other party is a mobile phone, but the conversation can be freely performed as with a normal mobile phone.

FIG. 3 is a schematic diagram of a mobile videophone system according to an embodiment of the present invention. In FIG. 3, 1 is the first base station of the mobile videophone system,
Reference numeral 2 is a second base station of the mobile videophone system, 3 is a first videophone which is a portable videophone terminal (mobile station) of the mobile videophone system, and 4 is a second videophone system of the mobile videophone system. A video phone, 5 is a first mobile phone which is a mobile phone terminal of a mobile video phone system, and 6
Is a second mobile phone of the mobile videophone system, 7 is an in-vehicle videophone of the mobile videophone system mounted in a passenger car, and 8 is a telephone line connecting base stations.

In the mobile videophone system according to the present embodiment, when the user calls the first videophone 3 to the second videophone 4, the first videophone 3 to the first videophone 3 are used.
The second video telephone 4 is called via the base station 1 and the second base station 2, and if the second video telephone 4 is in a state of being able to receive the video telephone communication, video telephone communication is performed and a conversation can be performed by the video telephone. At this time, the first video telephone 3
The image of the face of the user of the second videophone 4 is displayed on the screen, and the image of the face of the user of the first videophone 3 is displayed on the second videophone 4.

At the beginning of the videophone communication, one slot in the time-division multiplexed frame is assigned to each of the voice data transmission and the image data transmission, so that the television image has a small number of frames, but the user can First videophone 3
Therefore, if a larger number of frames or faster image data transmission is requested, the number of slots for image data transmission is increased and the moving image becomes a natural image. The faster image data transmission is performed by the switch provided in the first video telephone 3, and when the number of slots of the first base station 1 and the second base station 2 is ready to be increased, The number of slots for transmitting image data of the videophone 3 and the second videophone 4 increases, and the number of frames of moving images increases. Although the present embodiment has been described by using the example in which the videophone communication is performed between the first videophone 3 and the second videophone 4, the case where the first videophone 3 is the in-vehicle videophone 7 will be described. Second as well
Videophone communication with the videophone 4 can be performed.

Further, the user of the first mobile phone 5 is to the first video phone 3 and the second video phone 4
The voice call can be made as usual, and the call can be made similarly to the conventional mobile phone. In this case, the first
No image is displayed on the screens of the video telephone 3 and the second video telephone 4. Further, it is also possible to make a call from the first video phone 3 and the second video phone 4 to the first mobile phone 5 and the second mobile phone 6. In this case, when the first videophone 3 and the second videophone 4 make a call, it can be recognized by the telephone number that the other party is a mobile phone, and the videophone performs voice-only voice communication. Since the first videophone 3 and the second videophone 4 do not transmit the voice data and the image data respectively using 1 slot, but perform only the voice data using 1 slot,
The line usage fee will be the same as the conventional mobile phone. It is understood that in the mobile videophone system according to the present embodiment, the videophone and the conventional mobile phone can be operated at the same time, and the systems can be integrated.

Next, the base station used in the mobile videophone system and the videophone which is a mobile station in this embodiment will be described below.

FIG. 4 is a block diagram of a base station of the mobile videophone system of this embodiment. In FIG. 4, 10, 11
Is an antenna for transmission / reception, 12 is an external amplifier, 13 is an amplifier for reception, 14 is a power amplifier for transmission, 15 is a base station modulator / demodulator,
Reference numeral 16 is a signal distribution / synthesis circuit including a high-frequency circuit, 17 is a digital modulation / demodulation circuit and a channel control circuit for controlling frequency channels for audio data and image data transfer, and time-division multiplexing frames and slots, and 18 is an interface circuit such as a voice codec. , 19 is an image data encoding / decoding circuit for encoding and decoding image data, 20 is an audio data encoding / decoding circuit for encoding and decoding audio data,
Reference numeral 21 is a line interface circuit to a mobile telephone, a videophone line 22 and a general telephone line 23, and simultaneously controls subscriber recognition and billing. Reference numeral 24 is a system control unit that controls and records the communication status of the entire base station, 25 is a CPU unit, and 26 is a storage unit including a RAM / ROM.

In the videophone communication, the radio waves sent from the videophone are received by the antennas 10 and 11, amplified by the external amplifier 12, and then amplified by the reception amplifier 13. The signal is frequency-converted and digitally demodulated by a signal distribution / synthesis circuit 16 and a channel control circuit 17, and a control signal of a predetermined slot, audio data and image data of a predetermined slot in the time-division multiplexed frame are extracted. These data are sent to the image data coding / decoding circuit 19 via the interface circuit 18, and are converted into transfer data of the image data. Also, the voice data is converted into transfer data by the voice data codec 20. For voice data, VCELP codec or PI-SE
Conversion from the compressed data format of the LP codec to the μ-Low PCM codec for general lines is generally used. Communication of voice data and image data from the base station to the videophone is the opposite.

In response to the videophone communication request from the videophone, the base station according to the present embodiment selects the number of slots used for other communication among the frequency channels managed by the system controller 24. Select fewer frequency channels and assign them to videophone communication. As a result, even if the user of the videophone requests the increase in the number of image data slots, the user can immediately respond. In addition, when it is requested to increase the number of image data slots in the frequency channel used by another user and all slots are already used, the above-mentioned FIG. 2 (a), (b) ，
As described with reference to (c), it is possible to move a slot used by another user to another frequency channel without interrupting communication. Further, when it is requested to increase the number of slots for image data in a frequency channel which is also used by another user and all slots are already in use, the system control unit 24 uses another frequency. It also has a function of searching for a slot that can be used by a channel and using it as a slot for image data.

FIG. 5 shows a block diagram of a videophone of the mobile videophone system in this embodiment. In FIG. 5, 30 is a whip antenna for both transmission and reception, 31 is a duplexer of an antenna having both a transmission band filter and a reception band filter, 32 is a linear power amplifier for transmission, 33 is a low noise amplifier for reception, and 34 is a transmission amplifier. Credit mixer, 34 'for receiving, 35 for digital modulating circuit, 36 for synthesizer circuit, 37 for receiving intermediate frequency amplifier, 38 for demodulator, 39 for frequency channel and time for audio and video data transfer. Channel control circuit for controlling division multiplexing frames and slots, 40 is an audio data coding / decoding circuit for coding and decoding audio data, and 41 is image data coding / decoding for coding and decoding image data. Circuit, 42 is a receiver for receiving, 43 is a very small microphone for transmitting, 44 is an LCD screen for displaying images and data, 45
Is a small camera including a lens and a small image pickup plate (CCD), 46 is a system control unit including a CPU unit 47 and a RAM / ROM storage unit 48, and 49 is a battery power source.

When the videophone receives the videophone communication from the base station, the received signal is the whip antenna 3
After passing through 0, the duplexer 31 and the low noise amplifier 33, it is converted into an intermediate frequency by the mixer 34 ', amplified by the intermediate frequency amplifier 37 and the demodulator 38, and demodulated into a digital signal. Channel control circuit 39
The control data of each slot, the audio data and the image data are separated, and the audio data passes through the audio data codec 40 and is further converted into audio by the receiver 42. Further, the image data is converted into image data in the image data coding / decoding circuit 41 and displayed on the LCD screen 44.

In the transmission of the videophone communication from the videophone to the base station, the image data is sent from the small camera 45 of the videophone to the image data code decoding circuit 41, and a predetermined data compression conversion is performed. In addition, voice is input from the microphone 43, is similarly subjected to data compression conversion in the voice data coding / decoding circuit 40, and is subjected to the time division multiplexing described with reference to FIG. 1B in the channel control circuit 39 together with the above image data. Control data, audio data, and image data are assigned to the slot configuration. This signal is subjected to phase shift keying (PSK) modulation by the digital modulation circuit 35, frequency converted by the mixer 34, amplified by the linear power amplifier 32, and sent from the whip antenna 30 to the base station.

FIG. 6 shows an external view of a video phone which is an example of the mobile video phone system in this embodiment. Here, components having the same function and effect as described with reference to FIG. 5 are designated by the same reference numerals, and detailed description thereof will be omitted. In FIG.
50 is a numeric keypad for dial number input, 51 is a rate increase / decrease key for requesting increase / decrease of the transmission rate of image data, 52
Is a power switch for turning on / off the power of the video phone, 53 is a hook key for on-hook / off-hook of the handset, 54 is a memory of the telephone number, the number of used slots and the cumulative number of slots, the charge or a numerical value equivalent to the charge is displayed Function keys for various processing functions such as.

The first video telephone 3, as shown in FIG.
When performing videophone communication between the second videophones 4, the videophone is placed in front of the face and a small camera is used.
At 45, it is placed so as to show the face of the user of the videophone. The user of the first videophone 3 first presses the power switch 52 to turn on the power of the first videophone 3. At this time, the first video telephone 3 prepares for communication with the first base station 1 such as position registration and reception of information from the first base station 1 and enters the incoming call waiting state. Similarly second
The video telephone 4 is also turned on, and is in an incoming call waiting state with the second base station 2.

When the user makes a call to the second videophone 4, the hook key 53 is pressed to bring the hook into the off-hook state,
Enter the other party's telephone number with the numeric keypad 50. When the first base station 1 recognizes from the telephone number that the connection destination is the video telephone, the user is most likely to use the frequency channel of the video telephone communication between the first base station 1 and the first video telephone 3. Allocate fewer frequency channels, and slot positions within the frame. At the same time, the first base station 1 requests the mobile videophone system to access the other party's telephone number, and the second videophone 4 of the other party is requested.
Wait for the incoming call completion signal. Also in the second base station 2, the first
When a frequency channel and a slot are assigned by the same operation as that performed by the base station 1 of the other party, the second video telephone 4 of the other party accepts the incoming call and presses the hook key 53, the other party Is heard from the receiver 42, and at the same time, the image from the other party's second videophone 4 is displayed on the LCD screen 44.
The videophone conversation begins.
Also, it is possible to have a conversation while displaying the line usage fee and the like on a part of the screen during the call.

When the caller requests a smooth motion due to the motion of the moving image, the rate increase / decrease key 51 for changing the image data transmission rate is pressed to increase the number of slots for image data transmission, and the LCD accordingly. Screen 44
The image displayed in is improved. This increase in the number of slots is proportional to the charge for using the line.

In the mobile videophone system of this embodiment, the call charge is paid by the caller side. Therefore, the increase in the transmission slot amount of image data is requested only by the key operation from the caller side. To increase. Also, when used as a voice telephone communication, a call charge is similarly charged to the calling party.

Further, in the mobile videophone system according to this embodiment, when a call is made from the videophone to the mobile phone, it is recognized that the other party's terminal is not the videophone but the mobile phone with the inputted telephone number. The conversation of only voice can be performed without processing the image data from the small camera 45. Also, when the call is made from the other party's terminal, if the other party's terminal is a video phone, pressing the hook key 53 causes the image from the other party's video phone to appear on the LCD screen 44, and at the same time the other party's voice can be heard. Come on. Also, if the other party is a mobile phone, pressing the hook key 53 with the ringing sound will allow you to hear the other party's voice.
No image appears on the D screen 44.

Furthermore, as another feature of the video telephone of this embodiment, a mode in which the receiver is placed on the ear of the caller during a call and a hands-free mode can be selected, but when used as a video telephone The hands-free feature is automatically activated, and in the case of voice-only phones, the mode of listening to the receiver is automatically selected.

In the above description, it was explained that the voice data used in the video telephone and the mobile telephone is transmitted using one slot, but in reality, at the same time as the voice data,
Communication of control data and control signals in time division multiplex communication performed between a base station and a mobile station is basically used for a conventional mobile phone or the like using a slot for voice data. The same method is used.

As described above, by using the mobile videophone system of the present invention, a conventional mobile phone and a videophone newly introduced in the future can be operated on the same system. In the description of the present invention, the case where each slot is used for voice telephone communication and video telephone communication has been described, but it goes without saying that the present invention is not limited to the example of the present invention.

[0049]

As described above, according to the present invention,
In the mobile videophone system, it is possible to operate the videophone and the mobile phone of the conventional mobile phone system on the same system, and it becomes possible to access from the videophone to the mobile phone or from the mobile phone to the videophone. It becomes possible to communicate with many portable terminals. In addition, it is possible to increase the utilization efficiency of frequency channels and use a television phone that uses a still image with a low image transmission rate and a clear high-speed moving image with a high transmission rate. For this reason, the user can use the videophone at a line usage fee that is cheaper than the conventional one. In addition, the user can select the image transmission rate on the videophone as needed and can talk while displaying the line usage fee on a part of the TV screen, so that a rate system that is easy for the user to understand can be introduced. Play.

[Brief description of drawings]

FIG. 1 is a diagram showing each frame of time division multiplexing of frequency channels of a mobile videophone system in an embodiment of the present invention and an example of slot use in the frame.

FIG. 2 increases the number of slots for image data to more than the number of empty slots in a frame in each frame of time division multiplexing of frequency channels of a mobile videophone system and an example of using slots in the frame in an embodiment of the present invention. It is a figure which shows the case where it requested.

FIG. 3 is a schematic diagram showing a mobile videophone system according to an embodiment of the present invention.

FIG. 4 is a block diagram showing a base station of a mobile videophone system according to an embodiment of the present invention.

FIG. 5 is a block diagram showing a videophone of a mobile videophone system according to an embodiment of the present invention.

FIG. 6 is an external view showing an example of a videophone of the mobile videophone system according to the embodiment of the present invention.

[Explanation of symbols]

1 ... 1st base station, 2 ... 2nd base station, 3 ... 1st video telephone, 4 ... 2nd video telephone, 5 ... 1st
Mobile phone, 6 ... second mobile phone, 7 ... in-vehicle videophone, 8 ... telephone line, 10, 11 ... antenna,
12 ... External amplifier, 13 ... Reception amplifier, 14 ... Transmission power amplifier, 15 ... Base station modulator / demodulator, 16 ... Signal distribution / synthesis circuit, 17 ... Channel control circuit, 18 ... Interface circuit, 19 ... Image data codec Circuit, 20 ... Voice data codec, 21 ... Line interface circuit,
22 ... Videophone line, 23 ... General telephone line, 24 ... System control unit, 25 ... CPU unit, 26 ... Storage unit, 30 ...
Whip antenna, 31 ... Duplexer, 32 ... Linear power amplifier, 33 ... Low noise amplifier, 34, 34 '... Mixer, 35
… Digital modulation circuit, 36… Synthesizer circuit, 37
... Intermediate frequency amplifier, 38 ... Demodulator, 39 ... Channel control circuit, 40 ... Audio data codec circuit, 41 ... Image data codec circuit, 42 ... Receiver, 43 ... Microphone, 44 ... LCD screen, 45 ... Small size Camera, 46 ... System control section, 47 ... CPU section, 48 ... Storage section, 49 ... Battery power supply, 50 ... Numeric keypad, 51 ... Rate increase / decrease key, 52
… Power switch, 53… Hook key, 54… Function key.

Claims (7)

[Claims] 1. A base station capable of communicating with a plurality of mobile stations, the mobile station capable of voice and image communication, and a communication system of the base station and the mobile station is time division multiplexing and phase shift keying. In a mobile videophone system having a communication means using a digital modulation method of the method, the communication means is a slot in a time division multiplex frame used for communication of voice data, and the time division multiplex used for communication of image data. A mobile videophone system characterized by different slots in the frame. 2. A base station capable of communicating with a plurality of mobile stations, the mobile station capable of voice and image communication, and a communication system of the base station and the mobile station being a time division multiplexing system and phase shift keying. In a mobile videophone system having a communication means using a digital modulation method, the communication means has different slots in a time division multiplexed frame used for communication of voice data and image data, and the communication of the voice data is different from each other. The mobile type is characterized in that one slot is used for each frame, and the communication of the image data is performed using at least one slot for each frame, and the number of slots used by the image data can be changed according to the data amount. Video phone system. 3. A base station capable of communicating with a plurality of mobile stations, the mobile station capable of voice and image communication, and a communication system between the base station and the mobile station is time division multiplexing and phase shift keying. In a mobile videophone system having a communication means using a digital modulation method, the communication means has different slots in a time division multiplexed frame used for communication of voice data and image data, and the communication of the voice data is different from each other. Using one slot position determined for each frame, communication of the image data is performed using at least one slot position determined for each frame, and the number of slots used by the image data is data. A mobile videophone system characterized by being variable depending on the quantity. 4. When the communication means communicates between a base station and a mobile station, the frequency channel designated by the base station has the smallest number of slots used for communication of other mobile stations and mobile phones. 4. The mobile videophone system according to claim 1, wherein the frequency channel is used. 5. In a frequency channel in which communication is performed between a base station and a mobile station by communication means, a slot of voice data of a mobile phone using the frequency channel is set to a frequency channel other than the frequency channel. 2. The slot has a function capable of shifting to a slot without interrupting the conversation.
The mobile videophone system according to 3 or 4. 6. When communication is performed between a base station and a mobile station by communication means, communication is automatically started at the lowest image transmission rate in which 1 slot is allocated to voice data and 1 slot to image data, and further, 6. A function to change the number of slots of image data to be charged for a communication line fee and change a transmission rate according to a user's request, according to claim 1, 2, 3, 4 or 5. Mobile videophone system. 7. A slot in which a line fee used for voice telephone communication, video telephone communication and other non-telephone data communication when communication between a base station and a mobile station is performed by communication means is used for communication. 4. A charge system proportional to the cumulative number of slots has a function of displaying a charge or a numerical amount equivalent to the charge on the mobile station.
The mobile videophone system according to 4, 5, or 6.