JP2003264874A - Mobile telephone and out-zone notice method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain a quick out-zone notice display by predicting a future reception level from a present reception level. <P>SOLUTION: After setting a perch channel and confirming a layer 1 (steps 2, 3), a reception level (L1) is measured (step 4), when the reception level (L1) is greater than a waiting permission level (Ltn), a reception level (L2) is furthermore measured (step 7). When the reception level (L2) is smaller than the reception level (L1), a reception level (L3) is furthermore measured (step 15), an arithmetic operation employing the reception levels (L1, L2, L3) is made to calculate a future prediction reception level (L4) (step 16). When the prediction reception level (L4) is smaller than a preset out-zone notice level (Ld), an out- zone notice indicating that the service area results in out-zone if movement continues is notified to a user (step 20). <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 telephone, and more particularly to an out-of-service notification method for displaying that a mobile phone is out of service area when it moves out of service area.

[0002]

2. Description of the Related Art A mobile telephone cannot make a call unless it is within a service area provided by a base station. Therefore, an out-of-range display is provided on the mobile phone to detect that the reception level has dropped below a certain level and notify the user that the current position is out of the service area.

A flow chart of standby channel selection in a conventional mobile telephone having such an out-of-range display function will be described with reference to FIG.

First, in the mobile telephone, a perch channel is set (step 2), and then it is determined whether or not layer 1 can be confirmed, that is, whether frame synchronization can be established (step). 3). Then, if the layer 1 can be confirmed, level detection (L1) is performed (step 4). And BCCH (Broadcast Control CHan)
nel: broadcast channel) is determined (step 5), and if it is determined that BCCH reception is completed, it is determined whether or not the standby condition is satisfied (step 5). 6). Specifically, the standby condition is whether or not the measured reception level (L1) is higher than the standby deterioration level (Lth). Here, the standby deterioration level (Lth) is a threshold level at which the mobile telephone cannot communicate when the reception level becomes lower than this level.

When it is determined in step 6 that the standby condition is satisfied, it is determined whether or not the transition to the control channel is possible (step 9). If it is determined that the transfer to the control channel is possible, the transfer processing to the control channel is performed (step 1
0), a standby state is set (step 11). When it is determined in step 9 that the transition to the control channel is impossible, the process of transitioning to the control channel is not performed and the standby state is set (step 11).

If the layer 1 cannot be confirmed in step 3, the BCCH reception is not completed in step 5, or the reception level (L1) is less than the standby deterioration level (Lth) in step 6,
It is determined whether the channel is the last channel (step 12). When it is determined in step 12 that the channel is the last one, "out of service" is displayed (step 13) and a perch frequency scan is performed (step 14). If it is determined in step 12 that the channel is not the last channel, the process returns to the perch channel setting process in step 2.

In the digital car telephone system (RCR STD-27), the flowchart for selecting the standby channel is shown in Appendix B. 2. The flow chart of zone transfer processing is shown in Appendix B. 7 are disclosed.

In such a conventional mobile telephone, for example, even when the mobile telephone is moving in a direction away from a certain service area and the reception level of the selected channel is decreasing, the reception level becomes a standby deterioration level ( If it does not become Lth) or less, "out of service" is not displayed. For example, as the reception level of the radio base station measured by the mobile telephone is t ₁ , t ₂ , t ₃ , and t ₄ , t ₁ = 9 [dBμV] → t ₂ = 6 [dBμV] →
t ₃ = 3 [dBμV] → t ₄ = 0 [dBμV],
When the standby deterioration level (Lth) is set to 0 [dBμV], in the conventional mobile telephone, no notice is given until the time t ₄ when the reception level becomes equal to or lower than the standby deterioration level (Lth) of 0 [dBμV]. However, at time t ₄ , the out-of-range display is performed and the user is suddenly shown to be out of range. That is, in the above-mentioned conventional mobile telephone, the reception level is detected, and the out-of-range display is performed only when the detected reception level is equal to or lower than the standby deterioration level. Therefore, the out-of-range display is performed without any notice to the user. Therefore, the user may suddenly become unable to talk when moving while talking.

In order to solve such a problem, various mobile telephones provided with an out-of-range caution function for notifying the user that if the user moves as it is before the out-of-range display, the user may be out of the service area in the future. Has been done.

For example, in Japanese Unexamined Patent Publication No. 6-276149, it is detected that the value of BER (Bit Error Rate) has exceeded a certain level or that a CRC error has occurred a predetermined number of times continuously, and the service area is removed. There has been proposed a mobile phone having an out-of-service warning function that detects that the mobile phone is about to enter.

Further, Japanese Utility Model Publication No. 5-68151 discloses that
Described is a mobile telephone which is provided with two electric field detection circuits, one for receiving an out-of-range warning and the other for receiving an out-of-range warning, and providing an out-of-range warning before the out-of-range warning. ing. However, this conventional mobile telephone has a problem that the circuit scale becomes large because two reception electric field detection circuits are required.

Further, in JP-A-6-13975, when it is confirmed that the reception level is decreased,
If the latest reception level is equal to or higher than the minimum transmittable / receivable level and the difference between the receive level and the minimum transmittable / receivable level is within the set dangerous range for a predetermined number of consecutive times, Mobile telephones have been proposed to notify the user of this. However, this conventional mobile phone requires arithmetic processing to calculate the difference between the reception level and the minimum transmittable / receivable level, and if the difference is within the dangerous range for a predetermined number of times consecutively, the out-of-range warning display is displayed. Since it is not performed, it is not possible to display the out-of-range warning promptly.

[0013]

None of the conventional mobile telephones described above predicts the future reception level, but displays the out-of-range warning display based on the current reception level and the reception status such as BER. Therefore, it is not possible to display the out-of-range caution display by detecting a case where the current reception status is good but there is a possibility that it may be out of range in the future.

The object of the present invention is to obtain the current reception level, BE.
By predicting not only the reception status of R etc. but also the reception level in the future, it is possible to quickly move out of service without increasing the circuit scale and without detecting that a certain predetermined state has occurred a predetermined number of times consecutively. It is to provide a mobile phone and an out-of-range notification method capable of displaying a caution.

[0015]

In order to achieve the above object, the out-of-service notification method of the present invention is an out-of-service notification method for displaying that the mobile phone is out of service when it moves out of the service area. Measuring the reception level of the radio wave from the radio base station and setting it as the first reception level (L1),
If the first reception level (L1) is higher than a preset predetermined level, measuring the reception level of the radio wave from the radio base station to obtain the second reception level (L2); If the second reception level (L2) is smaller than the first reception level (L1), the reception level of the radio wave from the radio base station is measured and the third reception level (L2) is measured.
3), a step of calculating a future predicted reception level (L4) by performing an operation using the first to third reception levels (L1, L2, L3), and the predicted reception level (L4). L4) is smaller than the preset out-of-service caution level, the step of notifying the user of the out-of-service caution that the user will move out of the service area if the user continues to move.

According to the present invention, when the second reception level (L2) is smaller than the first reception level (L1), it is determined that the reception level is decreasing with time, and the third reception level (L3) is determined. ) Is measured, and the reception level (L1, L2, L3) from the first to third reception levels is used for the future reception level (L
If 4) is predicted and the predicted reception level is smaller than the preset out-of-service caution level, it is determined that the mobile phone will be out of the service area if it continues to move, and the out-of-service caution is notified to the user. It was done.

Therefore, according to the present invention, it is promptly possible that the mobile telephone may be out of the service area by only measuring the reception level without increasing the circuit scale and without measuring the BER. It can be detected and notified to the user.

Further, the method of notifying the user of the out-of-service notice may be a method of displaying an out-of-service notice or a method of generating an out-of-service warning sound.

Furthermore, the method of calculating the future predicted reception level (L4) by performing the calculation using the first to third reception levels (L1, L2, L3) is at least 2
A method of calculating the predicted reception level by multiplication may be used.

[0020]

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

(First Embodiment) The flowchart of FIG. 1 shows the operation of selecting a standby channel of a mobile telephone with an out-of-service notice function according to a first embodiment of the present invention.

First, in the mobile telephone, a perch channel is set (step 2), and then it is determined whether or not layer 1 can be confirmed, that is, whether frame synchronization can be established (step). 3). Then, if the layer 1 can be confirmed, level detection (L1) is performed (step 4). And BCCH (Broadcast Control CHan)
nel: broadcast channel) is determined (step 5), and if it is determined that BCCH reception is completed, it is determined whether or not the standby condition is satisfied (step 5). 6). Specifically, the standby condition is whether or not the measured reception level (L1) is higher than the standby permission level (Ltn). Here, the standby permission level (Ltn) is a level at which communication is possible.

When it is determined in step 6 that the standby condition is satisfied, level detection (L
2) is performed (step 7). Then, the reception level (L1) detected in step 4 and the reception level (L2) detected in step 7 are compared (step 8), and when the reception level L1 is larger than the reception level L2, that is, the reception level If is decreasing with the passage of time, level detection (L3) is further performed (step 15). Then, the reception level L measured in the past
The future reception level L4 is predicted using 1, L2 and L3 (step 16). When predicting the reception level L4 in the future, the least square method or the like may be used, or another method may be used.

Next, it is judged whether or not the predicted reception level (L4) is lower than the out-of-service caution level (Ld) (step 17), and the predicted reception level (L4) is lower than the out-of-service caution level (Ld). If it is smaller, it is determined whether it is the last channel (step 18). If it is not the last channel, it is judged whether zone transfer is possible (step), and if zone transfer is possible, zone transfer processing is performed (21). When it is determined in step 19 that the zone transfer is impossible, "peripheral warning" is displayed (step 20), and then perch frequency scanning is performed (step 14).

When it is determined in step 8 that the reception level (L1) is less than or equal to the reception level (L2), and in step 17 that the predicted reception level (L4) is greater than or equal to the out-of-range caution level (Ld). In this case, it is determined whether the transfer to the control channel is possible (step 9). When it is determined that the transfer to the control channel is possible, the transfer processing to the control channel is performed (step 10), and the standby state is set (step 11).
When it is determined in step 9 that the transition to the control channel is impossible, the process of transitioning to the control channel is not performed and the standby state is set (step 11).

If the layer 1 cannot be confirmed in step 3, or if the BCCH reception is not completed in step 5, the reception level (L1) is obtained in step 6.
Is less than or equal to the standby permission level (Ltn), it is determined whether or not it is the last channel (step 1
2). When it is determined in step 12 that the channel is the last one, "out of service" is displayed (step 13) and a perch frequency scan is performed (step 14). If it is determined in step 12 that the channel is not the last channel, the process returns to the perch channel setting process in step 2.

Next, the process for determining whether or not the zone shifting process, which is performed in step 19 in FIG. 1, is possible will be described in detail with reference to the flowchart in FIG.

First, it is determined whether or not the reception level (L3) measured in step 15 is lower than the standby deterioration level (Lth) (step 24). When the reception level (L3) is equal to or higher than the standby deterioration level (Lth), the maximum value Lp (max) of the reception level in the peripheral zone
Is larger than the sum of the reception level (L3) and the zone shift level difference ΔL (step 25). Here, the zone shift level difference ΔL includes (standby permission level (Ltn) -standby deterioration level (Lt
h)) Set the above value.

In step 25, if the maximum value Lp (max) of the reception level in the peripheral zone is larger than the value obtained by adding the reception level (L3) and the zone shift level difference ΔL, it is determined that zone shift is possible, and step Then, the process proceeds to the zone shift process 21.

In step 24, the reception level (L3)
Is smaller than the standby deterioration level (Lth), it is determined whether or not the maximum value Lp (max) of the reception levels of the peripheral zones is larger than the standby permission level (Ltn) (step 26). When it is determined in step 26 that the maximum value Lp (max) of the reception level of the peripheral zone is higher than the standby permission level (Ltn), it is determined that the zone transfer is possible, and the process proceeds to the zone transfer processing of step 21. On the contrary, in step 26, the maximum value Lp (max) of the reception level of the peripheral zone is the standby permission level (L
If it is determined to be equal to or less than tn), it is determined that zone transfer is impossible, and the process proceeds to the process of displaying "out-of-range caution" in step 20.

As described above, in the out-of-service notification method by the mobile telephone of this embodiment, when the reception level (L2) measured in step 7 is smaller than the reception level (L1) measured in step 4, the reception level is Is determined to decrease over time, the reception level (L3) is further measured in step 15, and the future reception level (L4) is predicted using these reception levels (L1, L2, L3). If the predicted reception level is lower than the preset out-of-service caution level (Ld), it is determined that the mobile phone will be out of the service area if the mobile phone continues to move as it is, and "out-of-service caution" is displayed. Therefore, according to the out-of-service area notification method according to the present embodiment, it is possible that the mobile phone may go out of the service area by only measuring the reception level without increasing the circuit scale and without measuring the BER or the like. It is possible to quickly detect and notify the user.

Next, the operation of the mobile telephone of this embodiment will be described in detail with reference to the drawings. In the following description, a case where the mobile phone takes a movement locus (α) and a movement locus (β) on the cell zone shown in FIG. 3 will be described.

As an example of the standby operation, the standby permission level (Ltn) is 4 [dBμV], the standby deterioration level (Lth) is 0 [dBμV], the out-of-range caution level (Ld) is 10 [dBμV], A zone, B Zone, C
The perch channels in the zone are different a and b, c and d, e and f, and the standby channels are different g and h, j and k, m and n, but the reception levels are the same. The zone shift level difference ΔL is defined by the standby permission level (Ltn) -standby deterioration level (Lth), that is, 4-0 = 4 [dB]
μV].

First, the operation when the mobile telephone of the present embodiment takes a movement locus (α) will be described. FIG. 4 shows the relationship between the movement locus (α) and the reception level.

For example, in the A zone, the mobile telephone
Channel a is set as the perch channel (step 2). Since the mobile phone has been able to confirm the layer 1 (establish frame synchronization) (step 3), level detection at time t ₁ is performed (step 4), for example, reception level (L1) = 9. [DBμV]
Memorize Next, the mobile phone receives the broadcast information of the BCCH (step 5) and then receives the reception level (L1).
= 9 [dBμV] is the standby permission level (Ltn) = 4
A condition such as larger than [dBμV] is satisfied and it is determined that the standby condition is OK (step 6), the level is detected at the time t ₂ (step 7), and the reception level (L2), for example.
= 6 [dBμV] is stored. Next, time t ₁ and time t ₂
Of the reception levels (L1, L2) are compared (step 8), and if the reception levels decrease with the passage of time,
That is, when the reception level (L1)> the reception level (L2), the level detection at time t ₃ is performed (step 15), and the reception level (L3) = 3 [dBμ], for example.
V] is stored. Then, by performing calculation using the reception levels (L1 to L3) at times t ₁ , t ₂ , and t ₃ ,
Prediction reception level at a future time t ₄ (L4) is calculated (step 16). Here, the reception level (L1)
Is 9 [dBμV] and the reception level (L2) is 6 [dBμV
V] and the reception level (L3) are 3 [dBμV], the predicted reception level (L4) is 0 [dBμ, for example.
V] is calculated.

Next, in step 17, the predicted reception level (L4) = 0 [dBμV] is equal to the out-of-range caution level (L
d) = lower than 10 [dBμV], it is determined in step 18 whether or not the channel is the last channel.
Although channel b still exists, channel b also performs the same process as channel a, so its explanation is omitted here and it is determined that it is the last channel, and the process proceeds to step 19. In the example shown in FIG. 3, zone transfer is impossible, so it is determined in step 19 that zone transfer is not possible, and in step 20, “out of service notice” is displayed.

Next, the process for determining whether or not the zone shifting process, which is performed in step 19 in FIG. 1, is possible will be described in detail with reference to the flowchart in FIG.

[0038] First, the reception at time t ₃ level (L
3) = 3 [dBμV] is the standby deterioration level (Lth)
Then, it is judged whether or not it is larger than = 0 [dBμV] (step 24). Here, the reception level (L3) = 3
[DBμV] is a standby deterioration level (Lth) = 0 [d
Since it is larger than B μV], the process proceeds to step 25. In step 25, the maximum value Lp (max) (-6 [dBμV]) of the reception level of the peripheral zone (B zone) is equal to the reception level L3 (3 [dBμV]) and the zone transition level difference (4).
Since it is smaller than 7 [dB μV], which is the value obtained by adding [dB]), the reception level L3 and the standby deterioration level (Lt
h) is determined (step 24), and in step 26, the maximum value Lp of the reception level in the peripheral zone (B zone) is reached.
Since (max) (−6 [dBμV]) is below the standby permission level (Ltn) = 4 [dBμV], it is determined that zone shifting is impossible. Therefore, the zone shift processing is not performed and the "outside service warning" is displayed (step 20),
A perch scan is performed (step 14).

By performing the above processing,
The mobile phone of this embodiment has a movement trajectory (α) in FIG.
, The reception level is the standby deterioration level (Lt
h) It is possible to predict the reception level 0 [dBμV] at the future time t ₄ at time t ₃ before it becomes 0 [dBμV], so that “out-of-range attention” can be promptly displayed before “out-of-range” is displayed. Can be displayed on the screen to alert the user.

Next, the operation when the mobile telephone of this embodiment takes a movement locus (β) will be described. FIG. 5 shows the relationship between the movement locus (β) and the reception level.

For example, in the A zone, the mobile telephone
Channel a is set as the perch channel (step 2). Since the mobile phone has been able to confirm the layer 1 (establish frame synchronization) (step 3), level detection at time t ₅ is performed (step 4), for example, reception level (L1) = 7. [DBμV]
Memorize Next, the mobile phone receives the broadcast information of the BCCH (step 5) and then receives the reception level (L1).
= 7 [dBμV] is the standby permission level (Ltn) = 4
A condition such as larger than [dB μV] is satisfied and it is determined that the standby condition is OK (step 6), and the level is detected at time t ₆ (step 7), for example, the reception level (L2).
= 3 [dBμV] is stored. Next, time t ₅ and time t ₆
Of the reception levels (L1, L2) are compared (step 8), and if the reception levels decrease with the passage of time,
That is, if that is the reception level (L1)> reception level (L2), level detection at the time t ₇ is performed (step 15), for example, the reception level (L3) = - 1 [dB
μV] is stored. By performing calculation using the reception level of the time _{t 5, t 6, t 7} (L1~L3), the predicted reception level at a future time t ₈ (L4) is calculated (step 16). Here, the reception level (L
1) is 7 [dBμV] and the reception level (L2) is 3 [dB]
μV] and the reception level (L3) are −1 [dB μV], so that the predicted reception level (L4) is −5 [dB], for example.
μV] is calculated.

Next, at step 17, the predicted reception level (L4) =-5 [dBμV] is the out-of-range caution level (L).
d) = lower than 10 [dBμV], it is determined in step 18 whether or not the channel is the last channel.
Although channel b still exists, channel b also performs the same process as channel a, so its explanation is omitted here and it is determined that it is the last channel, and the process proceeds to step 19. In the example shown in FIG. 3, since zone transfer is possible, it is determined in step 19 that zone transfer is possible, and zone transfer processing to the C zone is performed in step 21.

Next, the process for determining whether or not the zone shift process in step 19 in FIG. 1 is possible will be described in detail with reference to the flowchart in FIG.

[0044] First, the reception at time t ₇ level (L
3) = − 1 [dBμV] is the standby deterioration level (Lt
It is determined whether h) is larger than 0 [dBμV] (step 24). Here, the reception level (L3) =
-1 [dBμV] is the standby deterioration level (Lth) = 0
Since it is equal to or lower than [dB μV], the process proceeds to step 26. In step 26, it is determined that the zone transfer is possible because the maximum reception level Lp (max) (7 [dBμV]) of the peripheral zone (C zone) is higher than the standby permission level (Ltn) = 4 [dBμV]. It for that reason,
Transition processing from the A zone to the C zone is performed (step 21).

By performing the above processing,
The mobile phone of this embodiment has a movement trajectory (β) in FIG.
In the case of taking, the zone transfer process from the A zone to the C zone is successfully performed.

(Second Embodiment) Next, a mobile telephone according to a second embodiment of the present invention will be described in detail with reference to the drawings.

The mobile telephone of this embodiment is shown in FIG. The flowchart of FIG. 6 is different from the flowchart showing the operation of the mobile telephone of the first embodiment shown in FIG. 1 in that step 21 for displaying “out-of-range caution” This is replaced with the step 22 that occurs.

According to the present embodiment, the user can recognize that he / she is in the "out of service" state by the caution sound generated from the speaker unit or the like, so that it is not necessary to look directly at the mobile telephone at any time, that is, The effect that visual support is unnecessary can be obtained.

In the first and second embodiments, the case where the "out of service" state is notified to the user by a display and a caution sound has been described, but the present invention is not limited to this. However, the present invention can be similarly applied to the case of notifying the user by other means such as a vibrator. Further, the present invention can be similarly applied even when a plurality of these notification means are used in combination.

Although not shown in the figure, the mobile telephones of the first and second embodiments described above have a recording medium recording a program for executing the out-of-service notification method described above. I have it. This recording medium may be a magnetic disk, a semiconductor memory or another recording medium. This program is read from the recording medium to the mobile phone and controls the operation of the mobile phone. Specifically, the above processing is realized by the CPU in the mobile telephone instructing the hardware resources of the mobile telephone to perform a specific processing under the control of this program.

[0051]

As described above, according to the present invention,
By predicting not only the current reception level and the reception status such as BER, but also the future reception level from the current reception level, a predetermined state is continuously generated a predetermined number of times without increasing the circuit scale. It is possible to obtain the effect of being able to promptly display the out-of-service notice without detecting that the user is present.

[Brief description of drawings]

FIG. 1 is a flowchart showing an operation of selecting a standby channel of a mobile telephone with an out-of-range attention function according to a first embodiment of the present invention.

FIG. 2 is a flowchart for explaining in detail step 19 of the zone shift processing in FIG.

FIG. 3 is a diagram showing a movement track of a cell zone and a mobile phone.

FIG. 4 is a diagram showing a relationship between a movement track (α) and a reception level.

FIG. 5 is a diagram showing a relationship between a movement locus (β) and a reception level.

FIG. 6 is a flowchart showing an operation of selecting a standby channel of a mobile telephone with an out-of-service notice function according to a second embodiment of the present invention.

FIG. 7 is a flowchart showing an operation of selecting a standby channel of a conventional mobile phone.

[Explanation of symbols]

2-22, 24-26 steps

Claims (9)

[Claims] 1. An out-of-range notification method for displaying that the mobile phone is out of the service area when the mobile phone moves out of the service area, the first reception level (L1) being obtained by measuring the reception level of the radio wave from the wireless base station. And when the first reception level (L1) is higher than a preset predetermined level, the reception level of the radio wave from the radio base station is measured and set as the second reception level (L2). Step, and if the second reception level (L2) is smaller than the first reception level (L1), the reception level of the radio wave from the radio base station is measured and set as the third reception level (L3). And the predicted reception level (L) in the future by performing the calculation using the steps and the first to third reception levels (L1, L2, L3).
4), and if the predicted reception level (L4) is smaller than a preset out-of-service caution level, it notifies the user of an out-of-service caution that the user will move out of the service area if the user continues to move. Out of range notification method. 2. The out-of-service notification method according to claim 1, wherein the method of notifying the user of the out-of-service warning is a method of displaying an out-of-service warning. 3. The out-of-range notification method according to claim 1, wherein the method of notifying the user of the out-of-range caution is a method of generating an out-of-range caution sound. 4. The first to third reception levels (L1,
4. The method for calculating a future predicted reception level (L4) by performing an operation using L2, L3) is a method for calculating the predicted reception level by the least square method. Out-of-service notification method described. 5. Means for measuring a reception level of a radio wave from a radio base station and storing it as a first reception level (L1), and the first reception level (L1) is higher than a preset predetermined level. When it is larger, a means for measuring the reception level of the radio wave from the radio base station and recording it as the second reception level (L2); and the second reception level (L2) being higher than the first reception level (L1). If it is also small, the means for measuring the reception level of the radio wave from the radio base station and storing it as the third reception level (L3), and the first to third reception levels (L1, L2, L3) are used. By performing the calculation, the future predicted reception level (L
4), and means for notifying the user of the out-of-service caution that if the predicted reception level (L4) is lower than the preset out-of-service caution level, it will be out of the service area if it moves as it is. Mobile phone. 6. The mobile phone according to claim 5, wherein the means for notifying the user of the out-of-service notice is a means for displaying an out-of-service notice. 7. The mobile phone according to claim 5, wherein the means for notifying the user of the out-of-range caution is a means for generating an out-of-range caution sound. 8. The first to third reception levels (L1,
8. The means for calculating a future predicted reception level (L4) by performing an operation using L2, L3) is a means for calculating the predicted reception level by the least squares method. Mobile phone as described. 9. A program for causing a computer to execute an out-of-service notification method for displaying that the mobile phone is out of service when the mobile phone moves out of the service area, and measures the reception level of radio waves from the wireless base station. The process of setting the first reception level (L1), and when the first reception level (L1) is higher than a preset predetermined level, the reception level of the radio wave from the radio base station is measured and the second reception level (L1) is measured. And the second reception level (L2) is smaller than the first reception level (L1), the reception level of the radio wave from the radio base station is measured to determine the third reception level (L2). Of the predicted reception level (L3) of the future by performing the processing for setting the reception level (L3) of the above and the calculation using the first to third reception levels (L1, L2, L3).
And a process of notifying the user of an out-of-service notice that if the predicted reception level (L4) is lower than a preset out-of-service caution level, if the user continues to move, the user will be notified of the out-of-service caution. Program to run on.