JP2006101180A - Portable terminal and position registing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a portable terminal and a method of registering the position of the portable terminal which suppresses the rapid consumption of the battery cell, even if making a sending process for registering the position in a place with poor radio environment. <P>SOLUTION: The portable terminal 103 measures the receiving level of radio waves sent from a radio base station by a radio unit 113 for registering the position, sets a high transmission power when the level is lower than a first threshold according thereto, and counts the number of continuous failures in transmission of position registeration data by an ACK failure number counter 122. If this exceeds a second threshold, the terminal 103 sets on a power control flag of a power control flag storage 121 to suppress the subsequent transmission power, thus reducing the consumption of a battery cell 117. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a mobile terminal device as a wireless terminal device that can be carried by a mobile phone or the like and a location registration method of the mobile terminal device, and more particularly, a mobile terminal device in which power control is performed when performing location registration of the device itself The present invention also relates to a location registration method for a portable terminal device.

  A mobile terminal device such as a mobile phone, a PHS (Personal Handy-phone System), or a PDA (Personal Digital Assistant) having a communication function can wirelessly perform a call or data communication. These portable terminal devices communicate with each other via a wireless base station close to the location of the destination. Therefore, each mobile terminal device registers its current location in a device called a home location register (HLR) and updates it to handle calls to the device. .

  For this reason, the portable terminal device makes a request for position registration to the home location register when the power is turned on or when the position registration area is changed due to movement. The request for location registration is performed wirelessly via a nearby radio base station, but it is not known whether the radio base station is relatively close or relatively far away. Therefore, conventionally, the position registration request is made with the transmission power maximized. However, in this case, when the mobile terminal device is repeatedly moved by transportation, a large transmission power is required every time a location registration request is made, and battery consumption becomes severe.

  Therefore, it has been proposed to refer to the reception level of radio waves transmitted from a radio base station when determining transmission power at the time of location registration (see, for example, Patent Document 1). In the first proposal, the reception level of radio waves from the radio base station is measured by using the fact that the radio wave reception level is lowered when the radio base station is far away, and the transmission power of the mobile terminal apparatus is predicted. I have to. Thereby, useless power consumption can be prevented and the life of the battery can be extended accordingly.

  Specifically, in the first proposal, a total of two types of semiconductor control circuits, that is, a first semiconductor control circuit and a second semiconductor control circuit are provided. The first semiconductor control circuit is always operated during transmission, but the second semiconductor control circuit is operated only when it is determined that the reception level is low, thereby controlling the power during transmission in two stages. In addition, power saving is realized by not operating unnecessary circuits.

  In addition, the user of the mobile terminal device sets a threshold value for controlling the transmission power, and the mobile terminal device controls the transmission power to be equal to or less than this threshold value even if the user does not turn off the power. It has also been proposed (see, for example, Patent Document 2). The second proposal aims to suppress electromagnetic waves emitted from the mobile terminal device. Therefore, in the second proposal, there is a possibility that satisfactory communication cannot be performed as a result of suppressing the influence of electromagnetic waves.

Therefore, the third is to limit the transmission power to a predetermined value or less only when the mobile terminal device is in a predetermined location by combining the mobile terminal device and position detection means such as GPS (Global Positioning System). It has been proposed as a proposal (see, for example, Patent Document 3).
Japanese Patent Laid-Open No. 7-115335 (paragraph 0014, FIG. 1) JP 2003-274457 A (paragraph 0016, FIG. 2) JP 2003-163631 A (paragraph 0015, FIG. 1)

  Thus, not unnecessarily increasing the transmission power is effective not only in obtaining the effect of extending the life of the battery but also in that it does not unnecessarily radiate electromagnetic waves to the surroundings. However, location registration is an important process for other mobile terminal devices to know the location of its own device, and transmission power that ensures that radio waves reach radio base stations while paying attention to electromagnetic radiation in specific areas such as hospitals. In addition, it is necessary to perform transmission processing without wasteful power consumption.

  In this sense, as shown in the first proposal, the intensity of the radio wave transmitted from the radio base station side is measured, and based on this, the minimum required transmission power is calculated and this transmission power is calculated. It is very important to transmit to the radio base station.

  By the way, when the mobile terminal device moves to a place far away from the radio base station, the intensity of the received radio wave becomes very low at the boundary portion of such a service area (cell). Therefore, the mobile terminal device side transmits the location registration data with the maximum transmission power or transmission power close thereto. However, if the communication environment is poor, location registration may fail even if transmission is repeatedly performed with such maximum transmission power or transmission power close thereto. In such a case, the battery is rapidly consumed. For example, when a mobile terminal device that has been turned on comes to a new area where location registration is to be performed, and transmission processing for location registration is started at maximum transmission power or transmission power close to this, If location registration fails continuously at that location, there is a problem in that the battery life is significantly reduced while the user does not sense.

  Accordingly, an object of the present invention is to provide a mobile terminal device and a mobile terminal device location registration method capable of suppressing rapid battery consumption even when transmission processing for location registration is performed in a place where the radio wave environment is poor. There is.

  In the first aspect of the present invention, (a) reception level detection means for detecting the level of radio waves received from a wireless base station to be communicated, and (b) the lower the level detected by the reception level detection means, the more wireless Transmission power calculation means for calculating the transmission power for transmission to the base station to a large value, and (c) whether the reception level of the radio wave detected by the reception level detection means is equal to or less than a first threshold value set in advance. And (d) data for location registration when the reception level is determined to be less than or equal to the first threshold value by the first threshold value determining means. (E) a transmission power calculated by the transmission power calculating means until the count value of the failure number counting means exceeds a preset second threshold value. Transmission power for transmitting location registration data and suppressing the transmission power when transmitting data for location registration to a transmission power lower than the value calculated by the transmission power calculation means when the second threshold value is exceeded The portable terminal device is provided with a control means.

  That is, according to the first aspect of the present invention, the transmission power for transmission to the radio base station is calculated based on the radio wave level received from the radio base station, and the radio wave reception level is equal to or lower than the first threshold value. In this case, the number of times that transmission of data for location registration fails continuously is counted by the failure count counting means. The position registration data is transmitted with the transmission power calculated by the transmission power calculation means until the count value exceeds a preset second threshold value. By reducing the transmission power at the time of data transmission to a transmission power lower than the value calculated by the transmission power calculation means, the power consumption is reduced in a communication environment where location registration fails continuously. Yes.

  In the invention described in claim 2, (a) reception level detection means for detecting the level of radio waves received from a radio base station to be communicated, and (b) a level detected by the reception level detection means is a predetermined value. Transmission power calculating means for calculating the transmission power when transmitting to the radio base station as the maximum transmission power when the power is lower than (c) this transmission when the data for location registration is transmitted at the maximum transmission power And (d) the level detected by the reception level detection means until the count value of the failure count counting means exceeds a preset second threshold value. While the position registration data is transmitted with the maximum transmission power while the value is lower than the predetermined value, the level detected by the reception level detecting means when the second threshold value is exceeded is the predetermined value described above. Also be and a suppressing transmission power control unit a transmission power to the transmission power lower than the maximum transmission power to the mobile terminal device be between less than the value.

  That is, in the second aspect of the invention, when the level detected by the reception level detection means is lower than a predetermined value, the transmission power calculation means calculates the transmission power when sending to the radio base station as the maximum transmission power. Is dealing. In this case, the location registration data is transmitted with the maximum transmission power until the count value of the failure count counting means exceeds a preset second threshold value. Thereafter, the location registration data is transmitted in the same communication environment. In the communication environment in which location registration continuously fails, the transmission power is suppressed to a transmission power lower than the maximum transmission power during the failure.

  In the invention according to claim 7, (b) a reception level detection step of detecting a level of a radio wave received from a radio base station to be communicated when there is a request for location registration of the own terminal; A transmission power calculation step for calculating the transmission power when transmitting to the radio base station to a larger value as the reception level is lower according to the reception level detected in the reception level detection step; and (c) radio waves detected in the reception level detection step. A first threshold value determining step for determining whether or not the received level is equal to or lower than a first threshold value set in advance; and (d) the received level is the first in the first threshold value determining step. A failure count step that counts the number of times that transmission of data for location registration fails continuously when it is determined that the threshold value is less than or equal to the threshold value, and (e) the failure count count step. The position registration data is transmitted with the transmission power calculated in the transmission power calculation step until the count value counted in exceeds the second threshold set in advance, and after the second threshold is exceeded, Again, the position with the transmission power suppressed to a transmission power lower than the value calculated in the transmission power calculation step until the radio wave reception level exceeds the first threshold value or the location registration data is successfully received by the radio base station. A transmission power control step for transmitting registration data is included in the location registration method of the mobile terminal device.

  That is, in the invention according to claim 7, when a request for location registration of its own terminal is made, the reception level of the radio wave received from the radio base station to be communicated is detected, and the transmission power is calculated based on this. The location registration data is transmitted. If this transmission fails continuously, the failure frequency counting step only when the transmission power determined in the first threshold determination step is relatively large as the reception level is determined to be lower than the first threshold. The position registration data is transmitted with the transmission power calculated in the transmission power calculation step until the count value counted in step 2 exceeds the preset second threshold value. Thereafter, the transmission power calculation is performed in the same communication environment. By transmitting location registration data with transmission power suppressed to a transmission power lower than the value calculated in the step, power consumption is reduced in a communication environment where location registration continuously fails.

  As described above, according to the present invention, the first proposal of the prior art is further improved. Even if the communication environment is poor and the transmission is performed with the maximum transmission power or the relatively large transmission power, the data for location registration can be In the case where it is not continuously received by the station, the transmission power is suppressed, and power consumption for transmission is suppressed until the communication environment such as approaching the radio base station is improved. As a result, it is possible to eliminate a situation in which power consumption for transmission is rapidly performed without the user being aware of it. Therefore, not only does the mobile terminal device that is highly functional and power consumption tends to increase with this, not only greatly contribute to the life of the battery, but also has an effect of suppressing unnecessary emission of electromagnetic waves.

  Furthermore, according to the present invention, since the opportunity for the mobile terminal device to transmit an unnecessarily high-power radio wave due to the location registration failure is reduced, the influence on the radio wave transmission / reception of other mobile terminal devices can be reduced. Can do.

  Hereinafter, the present invention will be described in detail with reference to examples.

FIG. 1 shows a main part of a communication system using a mobile terminal device according to an embodiment of the present invention. The communication system 100 includes a plurality of radio base stations such as a first radio base station 101 ₁ and a second radio base station 102 ₂ arranged adjacent to the _first radio base station 101 _1. ing. First first service area (cell) 102 ₁ of the radio base station 101 _1, overlaps the second radio base station 102 a second service area 102 ₂ of ₂ part. Accordingly, even when the mobile terminal device 103 moves from point A to point B and point C in the _first service area 102 ₁ and finally moves to the second service area 102 ₂ , for example. The handover (tracking exchange) is possible between the first and second radio base stations 101 ₁ and 101 ₂ without interruption of communication.

  FIG. 2 shows an outline of the circuit configuration of the mobile terminal device used in this embodiment. The portable terminal device 103 includes a control unit 111 including a CPU (Central Processing Unit) (not shown), a ROM (Read Only Memory) storing a control program, and the like. The control unit 111 is connected to a wireless unit 113, an operation unit 114, a storage unit 115, and a display unit 116 via a bus 112 such as a data bus. The battery 117 is used to supply power to each unit in the mobile terminal device 103.

Here, the radio unit 113 is a circuit part that communicates with a radio base station such as the _first radio base station 1011 shown in FIG. The operation unit 114 is configured by input / output devices including a key switch (not shown) arranged on the wireless unit 113, a touch panel, a pointing device such as a mouse, and the like. The storage unit 115 is configured by a memory such as a RAM (Random Access Memory). In a non-illustrated nonvolatile memory area of the storage unit 115, a power control flag storage unit 121 that stores a power control flag indicating whether or not to perform power control during transmission in an on / off state, and a position registration request An ACK (ACKnowledge) failure number counter 122 for storing the number of reception failures is provided. The display unit 116 is configured by a liquid crystal display or organic EL (organic electroluminescence), and the data input by the user from the operation unit 114 and the data received by the mobile terminal device 103 are visually displayed. . In this embodiment, when the portable terminal device 103 is in distance away from the radio base station such as a wireless base station 101 _1, switching to the control to reduce the transmission power A when the repeated control of the position registration, the A display to that effect is displayed on the display unit 116.

  By the way, when the mobile terminal device 103 shown in FIG. 1 is turned on or moved to a different location registration area, the position (wireless base station 101) is determined based on the radio wave received from the wireless base station 101. It is determined, and transmission for performing location registration in an HLR (Home Location Register) (not shown) is performed.

For example, when the mobile terminal device 103 performs location registration at the point A in the _first service area 102 ₁ and when performs location registration at the point B, the distance to the _first radio base station 101 ₁ is Different. Accordingly, the control unit 111 of the portable terminal device 103 as when the distance to the first radio base station 101 ₁ is long in the location registration, control is performed so as to increase the transmission power of the radio unit 113 to the public. This control is performed based on the result of measuring the reception level of radio waves received from the radio base station 101.

FIG. 3 shows the flow of location registration processing performed by the control unit of the mobile terminal device of this embodiment. Here, a description as the mobile terminal device 103 is present in the first service area 102 _1. When there is a request for location registration, for example, when the power of the mobile terminal device 103 is turned on (step S201: Y), the control unit 111 is closest to the radio unit 113 in the first radio base station 101. The reception level of the radio wave transmitted from ₁ is measured (step S202). Then, it transmits the location registration data for position registration at a transmission power corresponding to the reception level of this measurement to the first radio base station 101 ₁ (step S203). Next, the content of the ACK failure frequency counter 122 shown in FIG. 2 is cleared, and the count value C is initialized to the value “0” (step S204). Here, the count value C of the ACK failure counter 122, when the portable terminal device 103 makes a request for location registration to the first radio base station 101 ₁ of nearest, there was no response ACK to this It is a value that records the number of consecutive times.

  Thereafter, the control unit 111 causes the wireless unit 113 to determine whether or not an ACK response to the location registration request is performed within a predetermined time (step S205). When ACK is received (Y), the location registration processing has been performed, and the series of processing ends (END).

  On the other hand, when an ACK response to the location registration request is not made within a predetermined time (step S205: N), a transmission power control process for making the location registration request is executed (step S206). This will be described in detail next. Then, the location registration data is transmitted (step S207), and the process returns to step S205. Here, if the ACK response to the location registration data is made within a predetermined time, the location registration processing is ended (end), but if the reception of the ACK response fails (step S205: N), step S206 and subsequent steps. This process is repeated until an ACK response is successful.

FIG. 4 specifically shows the transmission power control process shown in step S206 of FIG. In this process, the control unit 111 first obtains the reception level of the current radio wave transmitted from the nearest radio base station 101 (first radio base station 101 ₁ ) from the radio unit 113 (step S221) and this It is determined whether or not the reception level is equal to or lower than the first threshold value (step S222). Here, the first threshold value is lower than the reception level obtained when the mobile terminal device 103 is close to one of the radio base stations such as the _first radio base station 1011, and the first service area 102 It is set to a value that is somewhat larger than the reception level normally obtained at the boundary part of the service area such as ₁ .

  When it is determined from this determination result that the reception level is higher than the first threshold value (N), the transmission power required for location registration is smaller than the maximum value. Therefore, in this case, since the transmission power is not consumed excessively, the power control flag indicating whether or not the power control for suppressing the consumption of the battery 117 (FIG. 2) is performed is turned off (step S223). That is, in this case, power control for location registration is performed without performing control such as reducing transmission power. This is the same as the conventional control.

  On the other hand, when the reception level is equal to or lower than the first threshold value in step S222 (Y), the control unit 111 reads the count value (number of reception failures) C of the ACK failure frequency counter 122 (step S224). And it is discriminate | determined whether this count value C is more than a 2nd threshold value (step S225). The current count value C is “0” because it is in an initialized state. On the other hand, the second threshold value is a predetermined positive integer equal to or greater than “1”. This value is set to, for example, a numerical value “3” at the time of shipment from the factory, but the user can change the value to another value of “1” or more by using the operation unit 114.

  Assuming that the second threshold value is set to “3”, the count value C is “0”, which is less than the second threshold value (N). Therefore, the control unit 111 increments the count value C of the ACK failure frequency counter 122 by “1” (step S226), sets the value to “1”, proceeds to step S223, turns off the power control flag, and performs processing. End (end).

  As described above, when the reception level determined in step S222 is relatively high (step S222: N), the count value C of the ACK failure frequency counter 122 is not counted up because the transmission power is relatively small, but the reception level is compared. If it is small (step S222: Y), the transmission power is relatively large, so the count value C of the ACK failure frequency counter 122 is counted up. After such processing is performed, the process proceeds to step S207 in FIG. 3 to retransmit the position registration data.

FIG. 5 shows a state of the location registration data transmission process shown in step S207 of FIG. In this process, first, it is checked whether or not the power control flag stored in the power control flag storage unit 121 shown in FIG. 2 is on (step S241). If the power control flag is not on (N), the normal transmission power is set (step S242). That is, in this case is set the transmission power increase or decrease the value of the transmission power according to the reception level of the radio wave received from the first radio base station 101 _1, the transmission of the position registration data is performed (step S243) . This will be described in relation to the processing in step S222 in FIG. If the reception level is higher than the first threshold (step S222: N), the location registration data is transmitted with a relatively small transmission power corresponding to this. On the other hand, when the reception level is equal to or lower than the first threshold value (step S222: N), the location registration data is transmitted with a relatively large transmission power corresponding to this. In the latter case, when the first reception level from the radio base station 101 ₁ is very low, so that the transmission of the location registration data at the maximum transmission power is performed. However, in this case, the count value C of the ACK failure frequency counter 122 is incremented by “1” (step S226).

  When the first retransmission is performed in this way (step S207 in FIG. 3), the process returns to step S205. Then, it is determined whether or not an ACK response to the transmission of the location registration data is performed within a predetermined time. As a result, if the ACK response is within a predetermined time, the location registration processing is successful (end).

  On the other hand, when the response of ACK is not within the predetermined time (step S205: N), the transmission power control process is performed again (step S206). In the transmission power control process shown in FIG. 4, the level of the reception level is checked in step S222. As a result, when the reception level is relatively high (step S222: N) and the transmission power is relatively small as a result, the power control flag is turned off assuming that the mobile terminal device 103 is stationary at the same position. In the same manner, the transmission of the location registration data is repeated with the relatively small transmission power. This is the same as the conventional control.

  On the other hand, the level of the reception level is checked in step S222. If the reception level is relatively low (step S222: Y) and the transmission power is relatively large as a result, the number of ACK failures with relatively large transmission power when the mobile terminal device 103 is stationary at the same position. The transmission of the position registration data is repeated while the count value C of the counter 122 is counted up. As a result, when the count value C of the ACK failure frequency counter 122 is counted up to “3” in step S226, the next location registration data is retransmitted (step S207 in FIG. 3). If no response is obtained, the number of failures is greater than or equal to the second threshold in the determination in step S225 (Y).

  In this case, a power control flag indicating whether or not to perform power control for suppressing consumption of the battery 117 (FIG. 2) is turned on (step S227). At the same time, the control unit 111 causes the display unit 116 (FIG. 2) to display that the transmission power has been suppressed (step S228). Thereafter, the process returns to step S207 (FIG. 3) to retransmit the position registration data.

  When the power control flag is turned on (step S227), the transmission power is suppressed to a specified threshold value in the power control of FIG. 5 (step S241: Y, step S244). Thereby, the location registration data is transmitted with the controlled transmission power (step S243).

  In this way, for example, when the transmission of location registration data is repeated with the maximum transmission power, the transmission power is suppressed after that when the number of failures exceeds the second threshold value. The transmission of the location registration data is repeated. In this state, since the display unit 116 of the mobile terminal device 103 displays that the transmission power is suppressed, the user moves to another place where the radio wave condition is good or turns off the mobile terminal device 103. It is possible to take measures such as giving up the immediate use.

Further, for example, it is assumed that the user has turned on the mobile terminal device 103 at point B in FIG. At this time, when the reception level from the _second radio base station 1012 becomes higher than the first threshold value in step S222 in FIG. 4 (N), the control unit 111 sets the communication destination to the first radio base station 101. _The power control flag can be turned off by switching from ₁ to the second radio base station 102 ₂ (step S223). The same applies when the point D is reached. If the reception level of the wireless unit 113 becomes high due to fluctuations in the communication environment such as the location changing as described above, or if reception at the wireless base station 102 side is possible even if the transmission power is currently suppressed, Registration will be completed. Therefore, it is possible to eliminate the inconvenience that the transmission process of the location registration data is continuously performed with a very large transmission power until then, and the consumption of the battery 117 (FIG. 2) can be suppressed.

  In the embodiment described above, the transmission power is suppressed to a value specified in advance when an environment where the radio wave condition is bad continues for a certain period of time. However, the present invention is not limited to this. For example, in the case where the corresponding mobile terminal device 103 is a device equipped with GPS, the second threshold value may be reduced as the movement amount per unit time increases according to the movement status of the mobile terminal device 103. The time until the start of transmission power suppression may be lengthened or eliminated. On the other hand, when the mobile terminal device 103 is stationary at the current position, a warning sound or the like is issued to take measures such as prompting the mobile terminal device 103 to be turned off. This is also effective in avoiding a situation where 117 is wasted.

It is a system block diagram showing the principal part of the communication system using the portable terminal device in one Example of this invention. It is a block diagram showing the outline | summary of the circuit structure of the portable terminal device used by a present Example. It is the flowchart which showed the process of the location registration which the control part of the portable terminal device of a present Example performs. 4 is a flowchart specifically showing a transmission power control process shown in step S206 of FIG. 3. It is a flowchart showing the situation of the transmission process of the location registration data shown in step S207.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Communication system 101 Wireless base station 102 Service area 103 Portable terminal device 111 Control part 113 Wireless part 116 Display part 117 Battery 121 Power control flag storage part 122 ACK failure frequency counter

Claims (7)

Reception level detection means for detecting the level of radio waves received from a wireless base station to be communicated;
Transmission power calculation means for calculating the transmission power when sending to the radio base station to a larger value as the level detected by the reception level detection means is lower,
First threshold value determination means for determining whether or not the reception level of the radio wave detected by the reception level detection means is equal to or less than a first threshold value set in advance;
A failure count counting unit that counts the number of times transmission of data for location registration fails continuously when the first threshold determination unit determines that the reception level is equal to or lower than the first threshold;
The position registration data is transmitted with the transmission power calculated by the transmission power calculation means until the count value of the failure frequency count means exceeds a preset second threshold value, and when the second threshold value is exceeded. A portable terminal device comprising: a transmission power control unit that suppresses the transmission power at the time of transmitting data for location registration to a transmission power lower than a value calculated by the transmission power calculation unit. Reception level detection means for detecting the level of radio waves received from a wireless base station to be communicated;
Transmission power calculating means for calculating the transmission power when sending to the radio base station when the level detected by the reception level detecting means is lower than a predetermined value as the maximum transmission power;
Failure count counting means for counting the number of times this transmission fails continuously when transmission of data for location registration is performed at the maximum transmission power;
While the level detected by the reception level detection means is lower than the predetermined value until the count value of the failure count counting means exceeds a preset second threshold value, transmission of location registration data with the maximum transmission power is performed. When the second threshold value is exceeded, the transmission power is suppressed to a transmission power lower than the maximum transmission power even when the level detected by the reception level detection means is lower than the predetermined value. A portable terminal device comprising transmission power control means.   3. The portable terminal device according to claim 1, further comprising a display unit that displays a message to the effect that the transmission power control unit suppresses transmission power.   Movement detection means for detecting movement, and when the transmission power control means suppresses transmission power, when it is determined that the movement detection means is not moving, a warning is issued and at least the transmission power is turned off. The portable terminal device according to claim 1, further comprising a stationary power supply control unit.   Movement detection means for detecting movement; when the transmission power control means suppresses transmission power, the second threshold is increased when it is determined that the movement detection means is moving; 3. The portable terminal device according to claim 1, further comprising second threshold value increasing means.   The transmission power control means returns transmission power to return the transmission power to the value calculated by the transmission power calculation means when the first threshold determination means detects a reception level exceeding the first threshold. The mobile terminal device according to claim 1, further comprising: A reception level detection step for detecting a level of radio waves received from a wireless base station to be communicated when a request for location registration of the own terminal is received;
A transmission power calculation step for calculating the transmission power when sending to the radio base station as the reception level is lower according to the reception level detected in this reception level detection step;
A first threshold determination step for determining whether or not the reception level of the radio wave detected in the reception level detection step is equal to or lower than a first threshold set in advance;
A failure count counting step for counting the number of times that transmission of data for location registration continuously fails when it is determined in the first threshold determination step that the reception level is equal to or lower than the first threshold; ,
The position registration data is transmitted with the transmission power calculated in the transmission power calculation step until the count value counted in the failure count counting step exceeds a preset second threshold value, and the second threshold value is transmitted. After that, until the reception level of the radio wave exceeds the first threshold value or the reception of the location registration data by the radio base station succeeds, the value calculated in the transmission power calculation step again. And a transmission power control step of transmitting location registration data with a transmission power suppressed to a low transmission power.

Images