JP2003163631A - Mobile communication system, portable terminal equipment and base station equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate influence of electromagnetic waves and to enable use of a portable terminal by limiting transmission power of the portable terminal to a certain level or below. <P>SOLUTION: When it is detected that portable terminal equipment enters a prescribed place by short distance radio communication equipment 102 or a GPS or the like, the portable terminal equipment 103 limits the transmission power to predetermined allowable transmission power or less. When prescribed communication quality can-not be obtained due to that, communication parameters used in communication with a base station such as a transmission rate, a kind of an error correction code and an encoding rate are changed in order to obtain the prescribed communication quality. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system including a mobile terminal device and a base station device.

[0002]

2. Description of the Related Art In a mobile terminal device typified by a mobile phone (hereinafter, the terminal device is also simply referred to as a terminal), electromagnetic waves emitted during signal transmission may affect medical equipment such as a pacemaker of the heart. Because of this, and because calls are annoying in public places, use in medical facilities and public places is often restricted.

[0003]

However, at present, mobile phones have become indispensable items for many people in terms of work or personal use, and it is expected that mobile terminals will become more widespread and their applications will be expanded. In such a situation, it is considered necessary to take some measures regarding the above-mentioned usage restrictions.

[0004] For example, if etiquette such as refraining from talking in a crowded person is taken into consideration and it is guaranteed that it does not affect medical equipment, use is permitted even in a hospital or the like. It is desirable to be done.

The present invention has been made under such a background, and an object thereof is to limit the transmission power of a portable terminal to a certain level or less to eliminate the influence of electromagnetic waves and enable the use of the portable terminal. The present invention provides a mobile communication system, a mobile terminal device, and a base station device.

[0006]

A mobile communication system according to the present invention is a mobile communication system having a base station for transmitting and receiving signals to and from a portable terminal device, and the portable terminal device has entered a predetermined place. When detecting that the mobile terminal device has entered a predetermined place, the mobile terminal device limits the transmission power to a value equal to or lower than a predetermined allowable transmission power.

As described above, by limiting the transmission power of the portable terminal to at least the preset allowable transmission power at least in the predetermined place, an unexpected accident which may occur due to the influence of electromagnetic waves generated when the portable terminal is used is prevented. Can be prevented. Moreover, since the transmission is not completely stopped, the possibility of using the mobile terminal can be left even if the quality of communication is degraded.

Particularly, when the predetermined communication quality cannot be obtained by limiting the transmission power to the allowable transmission power or less,
It is preferable to change communication parameters used in communication with the base station so that the predetermined communication quality is obtained.
This makes it possible to achieve both the use of the mobile terminal and the mitigation of the influence of electromagnetic waves.

The communication parameter is, for example, at least one of a transmission rate, a type of error correction code, and an encoding rate.

A mobile terminal device according to the present invention is a mobile terminal device for transmitting / receiving a signal to / from a base station, the position detecting means for detecting that the mobile terminal device has entered a predetermined place, and the mobile terminal. When it is detected that the device has entered a predetermined place, the control device limits the transmission power to a predetermined allowable transmission power or less.

The position detecting means of the portable terminal device has a short-range wireless communication means for communicating with an external short-range wireless communication means installed at a predetermined place, and is located within a communicable range with the device. It is possible to determine that the user has entered the predetermined place by detecting the entry. Alternatively, the position detection means has a means for detecting the current position of the mobile terminal device, by inquiring to the base station whether or not the detected current position corresponds to the predetermined place,
Alternatively, the judgment can be made based on the stored data in itself. Further, the control means can limit the transmission power to a predetermined allowable transmission power or less even when receiving a predetermined instruction from the user.

A base station device according to the present invention is a base station device for transmitting / receiving a signal to / from a portable terminal device, the detecting means for detecting that the portable terminal device has entered a predetermined place, and the portable terminal. And a means for changing communication parameters used in communication with the mobile terminal device in response to a received signal from the mobile terminal device when it is detected that the device has entered a predetermined place. To do.

The detecting means of the base station device can detect that the mobile terminal device has entered the predetermined place based on the notification from the mobile terminal device. Alternatively, the detection unit receives the notification of the current position from the mobile terminal device, and determines whether the current position corresponds to the predetermined location based on a database, thereby causing the mobile terminal device to determine the predetermined position. It is also possible to determine whether or not the user has entered the place, and to notify the portable terminal device to that effect when it is determined that the user has entered the predetermined place.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a schematic configuration of a mobile communication system according to the first embodiment of the present invention. In this figure, only one base station 101 and one mobile terminal 103 as the components of the system are shown. In reality, there are a plurality of each. As the mobile terminal 103 moves, the mobile terminal 103 communicates with other mobile terminals and fixed-line telephones via communication with the nearest base station 101. On the other hand, specific place 1
04 is provided with a BT-equipped device 102 including a Bluetooth (trademark) module (hereinafter, Bluetooth is simply referred to as BT) as an example of a short-range wireless communication unit. At the specific place 104, it is expected that there will be a crowd of people who may be adversely affected by electromagnetic waves emitted from the mobile terminal 103, such as hospitals and institutions where medical equipment and electronic equipment are present, or mobile phone calls may be annoying. Facilities include movie theaters, performance venues, and entertainment venues. The specific place 104 is such a fixed place,
It may be a moving object such as an ambulance or a train, or a person wearing a medical device such as a specific cardiac pacemaker. The cell 10 which is the communicable range of the device 102 with BT
5 has a radius of several tens of meters. One BT
When the attached device 102 cannot cover the entire range of the specific place 104, a plurality of BT attached devices 102 are arranged so that the specific place 104 can always receive information from the BT attached device 102.

As will be described later, a corresponding Bluetooth module is also provided in the mobile terminal 103 as an example of short-range wireless communication means. The BT-equipped device 102 constantly broadcasts a predetermined signal, and when the mobile terminal 103 enters the cell 105, the mobile terminal 1
The short-distance wireless communication means 03 makes the signal and becomes able to communicate mutually. In the present embodiment, from the BT-equipped device 102,
Information indicating allowable transmission power (transmission power capable of suppressing the radiation level of electromagnetic waves within a range allowed at a specific place) defined at the location is received. Note that, naturally, the transmission power used in the short-range wireless technology is less than or equal to the allowable transmission power.

The portable terminal 103 which has obtained the allowable transmission power information
Transmits the information to the base station 101. When the base station 101 and the mobile terminal 103 communicate with each other in this state, the base station 1
01 and the mobile terminal 103 control various communication parameters so as to obtain a predetermined communication quality while limiting the transmission power of the mobile terminal 103 to an allowable level or less. The communication parameter here means at least one of a transmission rate, a type of error correction code, a coding rate (coding rate), a spread factor (in the case of CDMA), and the like. Further, the predetermined communication quality is the minimum communication quality that can achieve the purpose of communication. For example, in the case of a telephone call, it is the quality of communication that corresponds to a sound quality that allows the conversation with the other party to be understood. Communication quality is generally QoS (Quali
ty of service), which is called bit error rate, block error rate, SIR (Signal Interference Rati
o), SNR (Signal to Noise Ratio), data delay, throughput, and the like. When the predetermined communication quality cannot be (or has become) unsatisfactory by lowering the allowable transmission power, the communication parameter used for communication with the base station is changed so that it can be maintained. For example, reduce the transmission rate or the coding rate. Conversely, by changing the communication parameters, it is possible to create a margin in the QoS and thereby reduce the transmission power by that amount. If the predetermined communication quality cannot be obtained even if the communication parameters are changed, the communication is disabled.

FIG. 2 shows a schematic configuration of the mobile terminal 103. The mobile terminal 103 includes an antenna 216, an RF transmitter / receiver 201, and a DSP as parts related to the telephone function.
(Digital Signal Processor) 204, speaker 205,
It includes a microphone 206 and an ear receiver 207. Mobile terminal 1
Reference numeral 03 denotes a control unit 208, a display unit 209, an operation unit 210, and R as parts related to the control of the mobile terminal.
It has an OM 212, a RAM 213, an imaging control unit 214, and a camera 215. The operation unit 211 corresponds to various keys and buttons. The ROM 212 stores a control program for realizing the later-described operation of this embodiment. The ROM 212 may include a writable memory such as a flash ROM. The mobile terminal 103 further includes a short-range wireless communication unit 211 such as the above-described Bluetooth and an antenna 217 therefor. The image capturing control unit 214 and the camera 215 are not essential constituent elements in the present invention. A power source unit using a battery is omitted in the drawing.

In the mobile terminal 103, the control unit 208 controls so that the allowable transmission power information is received from the BT-equipped device 102 using short-range wireless communication, and the information is stored in the RAM 213. When the mobile terminal 103 performs communication, communication parameter setting is performed so as to satisfy the condition of the allowable transmission power stored in the RAM 213 and the condition of the determined QoS. The mobile terminal 103 transmits information regarding the change of the set communication parameter to the base station 101. Instead of this, the mobile terminal 103 may first notify the base station 101 of the allowable transmission power information and change the communication parameter according to the instruction of the base station 101. The mobile terminal 103 is the device 102 with BT for a certain period or more.
When the signal is not received from the base station 1, it is determined that the signal has been emitted from the specific place 104, and the base station 1 transmits the information for transmitting the transmission power limit cancellation.
Send to 01.

In this embodiment, the mobile terminal 103
It is assumed that the mobile terminal 103 voluntarily performs the operation of reducing the transmission power of the transmission power to the allowable transmission power. In this case, in the system that controls the transmission power of the mobile terminal 103 from the base station 101, the mobile terminal 103 is
When the instruction to increase the transmission power is received from 01, if the allowable transmission power cannot be satisfied if the transmission power is increased according to the instruction, the instruction is ignored. Alternatively, in some systems, the base station 101 takes the initiative and the mobile terminal 10
It is also possible to control the transmission power in consideration of the allowable transmission power with respect to No. 3.

FIG. 3 shows a schematic configuration of the BT-equipped device 102. The BT-equipped apparatus 102 includes an antenna 301 and a short-range wireless communication unit 302 for transmitting and receiving a BT signal, a data processing execution unit 303 (for example, configured by a DSP) that processes the transmission / reception data, and the data processing execution unit 3
ROM 305 and RAM 30 used by
4 and a control unit 306 that controls each of these units.

In the BT-equipped device 102, the data processing execution unit 30 is provided so that the allowable transmission power information of a specific place stored in the ROM 305 or the RAM 304 can be transmitted.
3. The control unit 306 controls the short-range wireless communication unit 302. As described above, the transmission power of the BT-equipped device 102 is controlled so as to be transmitted within a range satisfying the allowable transmission power. By this control, the cell 10 of the device 102 with BT is
The range of 5 is decided.

FIG. 4 shows a schematic configuration example of the base station (base station apparatus) 101. The base station 101 includes an antenna 401 that exchanges signals with the mobile terminal 103, and the antenna 4
01 connected to the RF unit 402, a baseband (BB) processing unit 403 connected to the RF unit 402, and a wired transmission line IF 40 connected to the baseband processing unit 403.
4, control unit 405 for controlling these, this control unit 405
The RAM 406 and the ROM 407 used by the. The wired transmission line IF 404 is connected to an external exchange device 408.

The base station 101 receives, via the antenna 401, information on the setting / cancellation of the allowable transmission power from the portable terminal 103 existing in the specific place 104, and the information is stored in the RAM.
The control unit 405 controls so that the data is stored in 406.
The base station 101 receives the notification from the mobile terminal 103,
Various parameters relating to communication with the mobile terminal 103 are changed in cooperation with the mobile terminal 103. Some mobile terminal 10
When the predetermined QoS is not satisfied when the transmission power of No. 3 is reduced to the allowable transmission power, the communication parameter with the mobile terminal 103 is changed. If the predetermined QoS is not satisfied no matter how the change is made, it means that the mobile terminal 103 cannot communicate at the specific place.

It should be noted that the transmission power of the mobile terminal 103 is not reduced to the permissible transmission power all at once, but is set to Qo.
While confirming the change of S and changing the communication parameter if necessary, the transmission power may be gradually reduced to the allowable transmission power. In addition, this control is performed by the base station 1 of FIG.
Instead of the control by 01, the control information from the switching device 408 can be used.

The operation example in this embodiment will be described in more detail below.

FIG. 5 shows a device with BT and a mobile terminal (MS: Mo
It is a sequence diagram which shows the specific example of the signal exchange regarding this invention between a bile station) and a base station (BS: Base Station).

The device with BT constantly generates a signal and transmits the allowable transmission power information to the portable terminal that has entered the cell (11, 12). In response to this, the mobile terminal sets the allowable transmission power in itself (13). This mode is called a transmission power limiting mode. Then, the mobile terminal transmits the allowable transmission power information to the base station (18). Based on this, the base station recognizes that the permissible transmission power is set in the mobile terminal and stores it (21).

If the allowable transmission power information is changed (14), the portable terminal sets the allowable transmission power again (15). Further, this is transmitted to the base station (19), and the base station recognizes and stores the new allowable transmission power setting (22). If no signal is received from the device with BT for a certain period of time (16), the setting of the allowable transmission power is canceled (17), and the fact is notified to the base station (20).
In response to this, the base station recognizes that the allowable transmission power setting for the mobile terminal, that is, the transmission power limitation mode has been released, and resets the memory (23).

FIG. 6 is a sequence diagram showing a specific example of signal exchange between the mobile terminal and the base station after the mobile terminal sets the allowable transmission power.

When the mobile terminal sets a parameter used for communication with the base station (31), the mobile terminal satisfies the permissible transmission power (within the power range) and transmits the communication parameter information to the base station. (34). The base station checks whether communication with the mobile terminal is possible (40). In this example, this is determined based on QoS, and if it is determined that communication is impossible, information indicating that is transmitted to the mobile terminal (35). In response to this, the mobile terminal changes the communication parameter to be used, and again transmits the communication parameter information within the range of the allowable transmission power to the base station (36). The base station checks whether communication with the mobile terminal is possible (41). For example, if communication is not possible this time, information to that effect is transmitted to the mobile terminal (37). The mobile terminal further changes the communication parameter (33) and transmits the parameter information to the base station within the allowable transmission power range (3).
8). In response to this, if the base station determines that communication is possible (42), it sends information notifying that communication is possible to the mobile terminal (39). The minimum required QoS may be different for telephone calls and data communications.

In this way, the communication parameters used between the mobile terminal and the base station are determined. If it is not determined that communication is possible no matter how the communication parameters are changed, communication of the mobile terminal is not permitted at that location.

There may be a case where the communication parameter information transmitted from the base station is not received by the base station because the transmission power is limited. In such a case, since the base station does not transmit the information indicating the communication failure, the mobile terminal transmits the parameter information, and if there is no response from the base station within a predetermined time, It can be regarded as "information for notifying communication". Further, in the example of FIG. 6, the parameter is changed by the initiative of the mobile terminal, but there may be a modification in which the communication parameter is decided by the base station as described above.

FIG. 7 is a flowchart showing a processing example of the mobile terminal (MS) in the present embodiment.

This process is started when the power of the portable terminal is turned on. Although the end condition is not described in the flow, it ends when the power of the mobile terminal is turned off.

When the power of the portable terminal is turned on and the MS enters a specific place (S11), the allowable transmission power information is obtained from the device with BT and the transmission power limitation mode is set (S1).
2). Then, the mobile terminal transmits the information to the base station (S13).

In this state, when the mobile terminal starts a call or communication (S14), the transmission power (and communication parameters as necessary) is changed (S15). In this example,
For simplification of description, the transmission power is described as being reduced to the allowable transmission power at one time, but it is also possible to reduce the transmission power stepwise as described above.

In this state, it is checked by communication with the base station as shown in FIG. 6 whether a predetermined condition is satisfied (S16). This predetermined condition is, for example,
It is whether or not a predetermined QoS is satisfied within the range of allowable transmission power. If such a combination of parameters is found, the process proceeds to step S20 described later. If not found, if the parameters can be changed (S17, Ye
s) and change (S18). The communication with the base station is performed again using the new parameters, and it is checked whether the predetermined condition is satisfied (S16). If you are not satisfied,
Returning to step S17, the parameter change is repeated. If the conditions are not satisfied even after changing all the parameters, it is determined that the transmission is impossible (S19). As a result, the state in which the mobile terminal cannot perform the transmission operation is maintained.
Then, it proceeds to step S23.

If the predetermined condition is satisfied in step S16, the transmission / reception operation of the portable terminal is executed (S2).
0). Until the transmission / reception ends (S21), the transmission / reception is continued unless the vehicle leaves the specific place (S22). If it is determined that the vehicle has left the specific place before the transmission / reception ends (S22, Yes), the process proceeds to step S24 described below. When the transmission / reception ends (S21, Yes), the process proceeds to step S23.

In step S23, it is checked based on the signal from the device with BT whether or not the vehicle has come out of a specific place. If not, the process returns to step S14. When it is determined that the vehicle has come out of the specific place (S23, Yes), the transmission power limiting mode is reset (S24) and the base station is notified of that (S25). As a result, the state before the portable terminal enters the specific place is restored.

FIG. 8 shows a schematic configuration of a mobile communication system according to the second embodiment of the present invention. In the present embodiment, a GPS (Global Positi
The satellite 109 for position detection in the oning system) is used. Accordingly, as shown in FIG. 9, the mobile terminal 10
3 is equipped with a GPS receiver 219 that receives a radio signal from the satellite 109. Further, as shown in FIG. 10, the base station 101 is provided with a position database 409 in which the position information of the transmission power limit of the mobile terminal is stored in advance.
In this position database 409, the permissible transmission power at that position can be registered in correspondence with each position subject to transmission power restriction. If the minimum position range based on the resolution of this position detection system is substantially the same as the range of the specific place 104, the target position registered in the position database 409 may be a point (point defined by longitude and latitude). If the range of the specific place 104 is larger than the minimum position range, the registration target position is set as a plurality of points, or is registered as a range of points (longitude and latitude range) instead of points. The location database 409 does not necessarily have to be in the base station 109, and it is sufficient that the base station can use the location database even in another location. If the location database is stored in the mobile terminal, it is not necessary for the mobile terminal to make an inquiry to the base station. The configuration other than these is the same as that of the first embodiment.

The operation of the second embodiment will be described below.

FIG. 11 shows the GP in the second embodiment.
It is a sequence diagram which shows an example of signal exchange between the satellite for S, a mobile terminal (MS), and a base station (BS).

As is well known, information is constantly transmitted from GPS satellites (51), and mobile terminals use multiple GPs.
The current position is detected based on the received signal from the S satellite (53). The mobile terminal transmits the detected position information to the base station at regular intervals (57). The base station having received this refers to the position database and checks whether or not the position is a target position for which allowable power setting is performed (61). In this case, the current position is the target position. The base station confirms the allowable transmission power of the position from the position database and sets the transmission restriction mode for the mobile terminal (62). Then, the allowable communication power is transmitted to the mobile terminal (58). At this time, if the allowable transmission power is known to the mobile terminal, it is sufficient for the base station to specify only the designation.

In response to this, the portable terminal sets the allowable transmission power and enters the transmission power limiting mode (54). Regarding the determination of the communication mode at this time, the same operation as described in FIG. 6 is performed.

After that, the position detection based on the signal from the GPS satellite is continuously executed (52, 55), and the detected position information is transmitted to the base station (59). When the base station detects that it is out of the target position of the allowable transmission power setting (63), it cancels the setting of the allowable transmission power for the mobile terminal (64), and also transmits cancellation information to the mobile terminal ( 60). In response to this, the mobile terminal resets the transmission power limiting mode by canceling the allowable transmission power setting (56).

FIG. 12 is a flow chart showing an example of processing of the mobile terminal in the second embodiment. As a premise of this processing, it is assumed that the current position information is periodically transmitted from the mobile terminal to the base station.

When the mobile terminal has entered a specific location, the base station refers to the location database based on the current location information transmitted from the mobile terminal, and detects the entry. The base station transmits the allowable transmission power information registered for the location to the mobile terminal. The mobile terminal receives this information and recognizes that it has entered a specific location (S3
1, Yes), and enters the transmission power limiting mode (S32).

In this state, when the mobile terminal starts a call or communication (S33), the transmission power (and communication parameter if necessary) is changed (S34). Then, Fig. 6
It is checked whether or not a predetermined condition is satisfied by the interaction with the base station as shown in (S35). As described above, this predetermined condition is, for example, whether or not a predetermined QoS is satisfied in the range of the allowable transmission power. If such a combination of parameters is found, the process proceeds to step S39 described later. If not found, if the parameter can be changed (S36), it is changed (S3).
7). The communication with the base station is performed again with this new parameter, and it is checked whether the predetermined condition is satisfied. If not satisfied, the process returns to step S36 to repeat the parameter change. If the conditions are not satisfied even after changing all the parameters, it is determined that the transmission is impossible (S38). As a result, the state in which the mobile terminal cannot perform the transmission operation is maintained. Then, the process proceeds to step S42.

If the predetermined condition is satisfied in step S35, the transmitting / receiving operation of the portable terminal is executed (S3).
9). Until the transmission / reception ends, the transmission / reception is continued unless the user leaves the specific place (S41). If it is determined that the user has left the specific place before the transmission / reception ends, the process proceeds to step S41 described below. When transmission / reception ends (S4
0), and proceeds to step S42.

In step S42, it is checked based on the signal from the GPS satellite whether or not the vehicle has left a specific place. If not, the process returns to step S33. When it is determined that the vehicle has come out of the specific place, the restriction mode is reset (S43). In this embodiment, since the base station receives the notification to that effect, it is not necessary to notify the base station from the mobile terminal. In this way, the state before the portable terminal enters the specific place is restored.

A combination of the second embodiment and the first embodiment is also conceivable. That is, the mobile terminal obtains not the permissible transmission power information but the position information from the BT-equipped device of the first embodiment and transmits the position information to the base station, and the base station refers to the position database to target that position. It can be determined whether it is a position.

Although the preferred embodiments of the present invention have been described above, various modifications and changes other than those mentioned above are possible. For example, the short-range wireless communication in the first embodiment is not limited to BT. Also in the second embodiment, the mobile terminal may interlock with the base station to detect the position without depending on the GPS satellite. Other,
Any position detecting means can be used as long as it can confirm that the mobile terminal has entered a specific place with a predetermined accuracy. Further, in the present system, when the allowable transmission power is a single fixed value common to each place, it is not necessary to transmit the allowable transmission power value, and it is sufficient to transmit the instruction to shift to the transmission power limit mode. Even when a plurality of levels of allowable transmission power are prepared, the allowable transmission power information to be transmitted does not need to include the values of the allowable transmission power of those multiple levels, and may be simply its identification information. In that case,
The portable terminal side holds in advance an allowable transmission power value corresponding to the identification information. Furthermore, it is also possible to allow the mobile terminal to shift to the allowable transmission power mode in response to the user's operation.

[0054]

According to the present invention, by limiting the transmission power of a portable terminal to a certain level or less to eliminate the influence of electromagnetic waves, it is possible to prevent the adverse effects on medical equipment and the like from occurring and to prevent the occurrence of adverse effects on the portable terminal. Can be used. As a result, it becomes possible to improve the convenience of the mobile terminal and further spread it.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a mobile communication system according to a first embodiment of the present invention.

2 is a block diagram showing a schematic configuration of a mobile terminal 103 in the system of FIG.

3 is a block diagram showing a schematic configuration of a device with BT 102 in the system of FIG.

4 is a block diagram showing a schematic configuration example of a base station 101 in the system of FIG.

5 is a sequence diagram showing a specific example of signal exchange between the BT-equipped device, the mobile terminal, and the base station in the system of FIG. 1 according to the present invention.

FIG. 6 is a sequence diagram showing a specific example of transmission / reception of a signal between a mobile terminal and a base station after the mobile terminal in the system of FIG. 1 sets an allowable transmission power.

FIG. 7 is a flowchart showing a processing example of a mobile terminal in the system of FIG.

FIG. 8 is a diagram showing a schematic configuration of a mobile communication system according to a second embodiment of the present invention.

9 is a block diagram showing a schematic configuration of a mobile terminal 103 in the system of FIG.

10 is a block diagram showing a schematic configuration example of a base station 101 in the system of FIG.

11 is a sequence diagram showing an example of signal exchange between a GPS satellite, a mobile terminal and a base station in the system of FIG.

12 is a flowchart showing a processing example of a mobile terminal in the system of FIG.

[Explanation of symbols]

101 ... Base station, 102 ... Device with BT, 103 ... Mobile terminal, 104 ... Specific place, 105 ... Cell of device with BT,
211, 302 ... Short-range wireless communication unit

Claims (15)

[Claims] 1. A mobile communication system including a base station for transmitting and receiving signals to and from a mobile terminal device, comprising position detecting means for detecting that the mobile terminal device has entered a predetermined location, The mobile communication system, wherein the mobile terminal device limits the transmission power to a predetermined allowable transmission power or less when it is detected that the terminal device has entered a predetermined place. 2. The portable terminal device communicates with the base station so as to obtain the predetermined communication quality when the predetermined communication quality cannot be obtained by limiting the transmission power to the allowable transmission power or less. The mobile communication system according to claim 1, wherein the communication parameter used in (1) is changed. 3. The mobile communication system according to claim 2, wherein the communication parameter is at least one of a transmission rate, a type of error correction code, and an encoding rate. 4. The position detecting means installs a device having a short-distance wireless communication means at the predetermined place, and a short-distance wireless communication means for communicating with the short-distance wireless communication means of the device. The mobile terminal device is installed in a mobile phone, and the mobile terminal device determines that the mobile terminal device has entered the predetermined location by detecting that the mobile terminal device has entered a range in which short-range wireless communication with the device is possible. Or the mobile communication system according to 3. 5. The position detecting means is a means which is built in the portable terminal device and detects the current position of the portable terminal device. The base station determines whether or not the detected current position corresponds to the predetermined place. The mobile communication system according to claim 1, 2 or 3, wherein the determination is made by inquiring or based on stored data in itself. 6. A mobile terminal device for transmitting and receiving a signal to and from a base station, the position detecting means for detecting that the mobile terminal device has entered a predetermined place, and the mobile terminal device is installed in a predetermined place. A mobile terminal device, comprising: a control unit that limits the transmission power to a value equal to or lower than a predetermined allowable transmission power when the entry is detected. 7. The control means changes communication parameters used in communication with the base station when a predetermined communication quality cannot be obtained by limiting the transmission power to the allowable transmission power or less. The mobile terminal device according to claim 6. 8. The mobile terminal device according to claim 7, wherein the communication parameter is at least one of a transmission rate, a type of error correction code, a coding rate, and a spread factor. 9. The position detecting means has a short-range wireless communication means for communicating with an external short-range wireless communication means installed at a predetermined place, and is within a communicable range with the device. 9. The mobile terminal device according to claim 6, wherein the mobile terminal device determines that the user has entered the predetermined place by detecting the fact. 10. The position detecting means has means for detecting the current position of the mobile terminal device, and inquires of the base station as to whether or not the detected current position corresponds to the predetermined place. The mobile terminal device according to claim 6, 7 or 8, wherein the determination is made based on the stored data in itself. 11. The mobile terminal device according to claim 6, wherein the control means limits the transmission power to a value equal to or lower than a predetermined allowable transmission power even when receiving a predetermined instruction from the user. 12. A base station device for transmitting and receiving a signal to and from a mobile terminal device, comprising: detecting means for detecting that the mobile terminal device has entered a predetermined place; and the mobile terminal device at a predetermined place. A base station device comprising: means for changing a communication parameter used in communication with the mobile terminal device in response to a received signal from the mobile terminal device when the entry is detected. 13. The base station apparatus according to claim 12, wherein the communication parameter is at least one of a transmission rate, a type of error correction code, a coding rate, and a spread factor. 14. The base station device according to claim 12, wherein the detection means detects that the mobile terminal device has entered the predetermined location based on a notification from the mobile terminal device. 15. The mobile terminal device, wherein the detection means receives a notification of the current position from the mobile terminal device, and judges whether or not the current position corresponds to the predetermined place based on a database. 13. The base station device according to claim 12, wherein the mobile terminal device is informed of whether or not the mobile terminal device has entered the predetermined place, and when it is determined that the mobile device has entered the predetermined place.