GB2348339A

GB2348339A - A mobile station comprising a control section for switching to a calling mode when reception from a satellite is below a threshold.

Info

Publication number: GB2348339A
Application number: GB0002323A
Authority: GB
Inventors: Hisashi Kawabata
Original assignee: NEC Corp
Current assignee: NEC Corp
Priority date: 1999-02-01
Filing date: 2000-02-01
Publication date: 2000-09-27
Anticipated expiration: 2020-02-01
Also published as: GB2348339B; JP2000224087A; GB0002323D0

Abstract

When communication between a mobile station and a satellite is interrupted eg because of a geographical condition, the communication data is stored for later transmission. If the quality of a received signal is lower than a threshold, the control section of the mobile station manually of automatically switches to an automatic calling mode. In the automatic calling mode, data to be sent is stored in a memory and the stored send data is automatically sent when the quality of receiving is above the threshold. The control section verifies transmission and instructs a display to display that the data has been sent. Send data may include voice messages, data from a data input terminal 20 or data from keys 19. Received signal quality is determined from error rate or signal level and the display may indicate failure of communication, the reason for failure, busy state of a communication partner, elapsed time since the automatic calling mode was set and the frequency with which the mobile attempts to re-call.

Description

MOBILE-SATELLITE COMMUNICATION SYSTEM BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile-satellite communication system, and particularly relates to a transmitter- distributor and an automatic transmission method when communication between a mobile station and a base station is disabled due to a geographical condition or otherwise 2. Description of the Related Art Generally, in a mobile-satellite communication system, when received field strength in a mobile station is low, communication is disabled in a place where a satellite is out of sight.

Therefore, various steps have been heretofore taken.

For example, for one measure, a method of using a dualmode terminal for switching a satellite mobile telephone system and a ground mobile telephone system in a mobile station is actually utilized. This method is effective in a place where a ground mobile telephone system set as a dual-mode is operated and can be used, however, the method has no effect in a place other than the above place.

For another measure, it is also general to install and utilize an outside antenna in a place where a satellite is always in sight, however, an outside antenna, a coupling cable and others are required in addition to equipment for a mobile station and mobility is deteriorated. Utilization during movement is disabled because a mobile station isconnected to an outside L antenna and a cable.

As described above, it is currently difficult to always communicate even if various measures are taken for a space station.

For example, as it depends upon a geographical condition in a position where a vehicle is run, the position of a mobile station in the vehicle and others whether communication between a mobile station and a satellite is enabled or not if the mobile station which belongs to a mobile-satellite communication system is used in the vehicle during movement, it is impossible to always communicate.

Further, in a mobile-satellite communication system utilizing orbiters, as the position of a satellite is moved even if the satellite is in sight if a mobile station is located indoors or near to large structure, it is impossible to always communicate.

Therefore, even if a user of a mobile station calls at desired time in the above place, probability that calling is established is low.

There is a. method of utilizing an electronic mail, voice message communication and others which do not respectively require immediatism in communicating, however, in a current mobile-satellite communication system, if a satellite is not within a range where it is in sight and calling fails in such a method, communication is given up or calling operation is repeated at a fixed interval until calling succeeds. In the latter case, if an interval of repeated calling and a period when a satellite exists in a range where it is in sight are not matched, communication is disabled. The probability of calling can be enhanced in a period when a satellite exists in a range where it is in sight by reducing an interval of repeated calling, however, there is a limit in reducing an interval of calling in view of control over congestion and it is a problem because the power consumption of equipment for a mobile station is increased.

In a conventional type mobile-satellite communication system described above, probability that calling fails is high because of a geographical condition and others, compare with ground mobile communication.

Therefore, for example, in ground mobile communication, as disclosed in Japanese published unexamined patent application No.

Hei 2-122737, technique for monitoring receive-sensitivity and others of a communication control channel bv multi-channel access (MCA) radio equipment, automatically informing it by voice under a predetermined condition that communication is disabled, automatically making a call when communication is enabled, informing that communication is enabled and starting communication is known.

However, according to this method, in a situation that communication is frequently disabled as in communication using orbiters, a user of a mobile station is required to start communication every time a call is automatically made and information that communication is enabled is received and, the method lacks serviceability.

There is also a problem that a user of a mobile station cannot easily know the result of communication according to a situation of communication in case information such as an electronic mail is communicated.

Therefore, an object of the present invention is to provide means for also enabling communication by simple operation by a user of a mobile station in a situation in which communication is frequently disabled due to a geographical condition and others of a mobile station which belongs to mobile-satellite communication and informing the user of the situation of the communication.

SUMMARY OF THE INVENTION In a first aspect, the present invention provides a mobile station for use in a communication system comprising said mobile station, a base station and a communication satellite for relaying communication between said mobile station and said base station, said mobile station comprising a control section for switching to a calling mode when the reception quality from a communication satellite is lower than a predetermined threshold and for executing a normal calling procedure when the reception quality is equal to or greater than said predetermined threshold ; wherein said control section comprises data storage means for, in said calling mode, storing data to be output from the mobile station, comparison means for comparing the quality of a received signal to said predetermined threshold, transmission means for initiating transmission of said data depending upon a result of the comparison, and display means for displaying whether the transmission of said data has been completed.

A preferred embodiment of the present invention provides a transmitter-distributor in a mobile-satellite communication system composed of a plural mobile stations, a base station and communication satellites for relaying communication between the above mobile station and the base station is characterized in that a mobile station comprises a control section for switching to a calling mode manually or automatically in case the quality of receiving from a communication satellite is lower than a defined value and executing normal calling processing in case the above quality is higher than the defined value and the above control section comprises data storage means for storing data to be sent, comparison means for comparing the quality of receiving a signal and a defined value, transmission means for automatically calling and transmitting as send data in case the output of the above comparison means is higher than the defined value and display means for displaying whether sending the above send data is completed or not.

The present invention also provides a transmission method of a communication system comprising a mobile station, a base station and a communication satellite for relaying communication between said mobile station and said base station, comprising the steps of : switching to a calling mode when the quality of a signal received by said mobile station from said communication satellite is lower than a predetermined threshold ; storing data to be output from said mobile station ; subsequently comparing the quality of said received signal and said predetermined threshold ; initiating transmission of said data when the quality of said received signal is equal to or greater than said predetermined threshold ; and displaying whether the transmission of said data has been completed.

BRIEF DESCRIPTION OF THE DRAWINGS Preferred features of the present invention will now be described with reference to the accompanying drawings, in which : Fig. 1 is a block diagram showing a mobile-satellite communication system.

Fig. 2 is a flowchart showing the flow of processing by a control section 14 of a mobile station 1 shown in Fig. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT A detailed explanation will be given of embodiments of the present invention in reference to the drawings as follows.

Fig. 1 is an explanatory drawing for explaining a mobile-satellite communication system according to the present invention. As shown in Fig. 1, the mobile-satellite communication system is composed of plural mobile stations 1, a base station 2 connected to a public telephone network 3 and a communication satellite 4 for relaying communication between the mobile station 1 and the base station 2.

The mobile station 1 is composed of an antenna 11 for sending and receiving a radio-frequency signal to/from the communication satellite 4, radio equipment and a modulator/demodulator 12 for processing a signal to be sent and received to/from the communication satellite 4 and modulating or demodulating voice and data, a receiving quality detector 13 for measuring the error-rate of a received signal and detecting the quality of receiving, a controller 14 for controlling the radio equipment and the modulator/demodulator 12 of the mobile station 1 and others, a memory 15 for storing send data and others, a display 16 for displaying the completion or the failure of sending and others for a user to verify a situation of the calling of the mobile station 1, a microphone 17 for inputting a voice message and others, a speaker 18 and operation keys 19 for setting calling and others.

A data terminal 20 for generating the contents and others of a message is also connected to the mobile station 1.

The above controller 14 controls so that the power source of each section of the mobile station 1 is turned on or off at a defined time interval for intermittent receiving to reduce the power consumption of equipment for the mobile station. The controller 14 also judges that communication is possible in case the mobile station 1 is in a receive mode and the quality of receiving detected by the receiving quality detector 13 exceeds a predefined value and sends data stored in the memory 15 via the radio equipment and the modulator/demodulator 12 and the antenna 11.

Referring to a flowchart shown in Fig. 2, the operation of the controller 14 will be described in the concrete below.

As shown in Fig. 2, the receiving quality detector 13 compares the error rate of a signal received by the mobile station 1 from the communication satellite 4 with the defined value and detects whether the quality of receiving is low and communication is disabled or not in-a step A0. If the quality of receiving is equal to the defined value or more, normal calling processing is executed in a step A10. In the meantime, if the quality of receiving is lower than the defined value, it is displayed on the display 16 that communication is disabled and when a user of the mobile station 1 operates an operation dey 19, an automatic calling mode is set in a step A1. Next, as automatic calling processing, send data from the data terminal 20 and others is stored in the memory 15 in a step A2.

As for send data, there are a voice message input from the microphone 17, data input from the data terminal 20 and a message input via an operation key 19.

Next, the mobile station 1 repeats a receive mode and a receive halt mode every fixed time according to the timer of the controller 14 and others, intermittently executes receiving operation and judges whether the receiving timing of the intermittent operation is in a receive mode or in a receive halt mode in a step A3. If the mobile station 1 is switched from a receive halt mode to a receive mode, the receiving quality detector 13 again measures the error rate (the quality) of a received signal and compares it with the defined value in a step A4. The defined value of the quality of receiving is set to the lower limit of the quality at which communication is-stably enabled.

In the step A3, if the mobile station is in a receive halt mode, it waits until the current mode is switched to a receive mode.

In the step A4, if the quality of receiving is equal to the defined value or more, send data is automatically called in a step A5. If the quality of receiving is lower than the defined value, processing is returned to the processing for judging receiving timing in the step A3 and enter a standby mode.

If calling is completed, send data stored in the memory 15 is automatically sent in a step A9.

The controller 14 monitors a situation in which the send data is sent, if the sending of all send data is completed, the controller instructs the display 16 to display the information of completion as the result of the communication and if the sending of send data fails, the controller instructs the display to display the information of failure in steps A6, A7 and A8.

If communication fails, processing is returned to the processing for judging receiving timing in the step A3 and enters a standby mode in the steps A6 and A8.

In the above embodiment, if the quality of a wave sent from the communication satellite 4 and received by the mobile station 1 is low and communication is disabled, an automatic calling mode is set by the operation of an operation key 19 by the user of the mobile station 1 in the step Al. However, the current mode may be also automatically switched to an automatic calling mode based upon the quality of receiving without depending upon setting by a user.

Also, the mobile station 1 compares the error rate (the quality) of a received signal detected by the receiving quality detector 13 with the defined value (the step-A4 shown in Fig. 2), however, it may be also judged using a receive level in place of the quality of receiving whether automatic calling is enabled or disabled. In this case, as time required for detection is shorter than time required for the detection of the error rate, there is effect that it can be judged in a short time whether automatic calling is enabled or disabled in a system such as an orbiter in which a situation of receiving is changeable in a short time.

Further, the controller 14 can instruct the display 16 to display not only the completion or the failure of calling but the frequency of calling, the reason of the failure of calling such as the failure of communication with a base station, a busy state of a communication partner, absence and others and elapsed time since an automatic calling mode is set respectively acquired in the process of control flow shown in Fig. 2.

In the automatic-transmitting circuit and the method of the mobile station for the mobile-satellite communication according to the present invention, as communication can be automatically started again even if a user does not set calling processing and data transmission processing, checking a state of communication when a state proceeds to a state in which communication is enabled in case the mobile station can only temporarily communicate with the satellite because of a geographical condition and others, the automatic transmitting circuit and the method of the mobile station for the mobile-satellite communication according to the present invention has effect that the serviceability of the user is particularly enhanced, compared with that of a conventional type.

The reason is that the mobile station detects the quality of receiving and automatically transmits stored data when the controller judges that communication is enabled.

The present invention also has effect that as the present invention is provided with a function for displaying the completion and the failure of the automatic transmission of send data, a user can verify transmission.

While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to this description. It is, therefore, contemplated that the appended claims will cover any such modifications or embodiments as fall within the true scope of the invention.

Each feature disclosed in this specification (which term includes the claims) and/or shown in the drawings may be incorporated in the invention independently of other disclosed and/or illustrated features.

Statements in this specification of the"objects of the t invention"relate to preferred embodiments of the invention, but not necessarily to all embodiments of the invention falling within the claims.

The description of the invention with reference to the drawings is by way of example only.

The text of the abstract filed herewith is repeated here as part of the specification.

According to the present invention, if a mobile station cannot always communicate with a satellite because of a geographical condition in a mobile-satellite communication system, calling from the mobile station is enabled. The control section of a mobile station manually or automatically switches to an automatic calling mode in case the quality of a received signal is lower than a defined value. In the automatic calling mode, after data to be sent is stored in a memory, the stored send data is automatically sent in case the quality of receiving is equal to the defined value or more. The control section verifies sending and instructs a display to display that all data is sent.

Claims

CLAIMS : 1. A mobile station for use in a communication system comprising said mobile station, a base station and a communication satellite for relaying communication between said mobile station and said base station, said mobile station comprising a control section for switching to a calling mode when the reception quality from a communication satellite is lower than a predetermined threshold and for executing a normal calling procedure when the reception quality is equal to or greater than said predetermined threshold ; wherein said control section comprises data storage means for, in said calling mode, storing data to be output from the mobile station, comparison means for comparing the quality of a received signal to said predetermined threshold, transmission means for initiating transmission of said data depending upon a result of the comparison, and display means for displaying whether the transmission of said data has been completed.
2. A mobile station according to Claim 1, wherein : said reception quality is determined by the detected error rate of a received signal.
3. A mobile station according to Claim 1, wherein : said reception quality is determined by the detected receive level of a received signal.
4. A mobile station according to any preceding claim, wherein : said display means is adapted to display the frequency of calling in said calling mode, a reason for the failure of the transmission of said data and an elapsed time since said calling mode was set.
5. A mobile station according to any preceding claim, wherein said mobile station is adapted to intermittently receive data and to transmit said data when reception of data is possible.
6. A communication system comprising a mobile station according to any preceding claim.
7. A transmission method of a communication system comprising a mobile station, a base station and a communication satellite for relaying communication between said mobile station and said base station, comprising the steps of : switching to a calling mode when the quality of a signal received by said mobile station from said communication satellite is lower than a predetermined threshold ; storing data to be output from said mobile station ; subsequently comparing the quality of said received signal and said predetermined threshold ; initiating transmission of said data when the quality of said received signal is equal to or greater than said predetermined threshold ; and displaying whether the transmission of said data has been completed.

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8. A mobile station or communication system substantially as herein described with reference to Figure 1 of the accompanying drawings.
9. A transmission method of a communication system substantially as herein described with reference to Figure 2 of the accompanying drawings.