JP2001157258A - Mobile communication terminal and its communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To find out a base station of excellent communication quality in a short time and efficiently replace the base station of a communication destination. SOLUTION: A reception result processing section 21 prepares a base station list to which a new base station indicated in information received from a base station information extract section 11 is appended and starts the measurement of reception electric field strength. When the measurement of the reception electric field strength is completed, a regression arithmetic processing section 23 uses a reception strength table on which an actually measured value of the reception electric field strength for each base station is recorded to obtain a regression function, and also obtains a predicted value of the reception electric field strength at a next measurement from this regression function and gives the result to an arithmetic result processing section 24. The arithmetic result processing section 24 revises the descriptions of the base station list so that the reception electric field strength is sequentially measured in the order of base stations whose prediction value of the reception electric field strength is higher. A measurement control section 22 allows a reception strength measurement section 10 to measure the reception electric field strength according to the sequence denoted by the base station list revised by the arithmetic result processing section 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication terminal using a cellular system for transmitting / receiving a radio signal to / from a base station and a communication method thereof, and more particularly to a base station of a communication destination with high efficiency. The present invention relates to a mobile communication terminal capable of selecting a station and a communication method thereof.

[0002]

2. Description of the Related Art A mobile communication terminal using a cellular system has
Communication is enabled by transmitting and receiving wireless signals to and from a number of base stations arranged in a communication service area. At this time, the mobile communication terminal appropriately measures the reception electric field strength of the radio signal transmitted from each base station in order to transmit and receive a radio signal to and from a base station having good communication quality, and performs communication based on the measurement result. Base stations to be switched one after another to continue the communication.

The operation of such a conventional mobile communication terminal when measuring the reception electric field strength of a radio signal will be described with reference to the flowchart of FIG.

[0004] A mobile communication terminal acquires information about a peripheral base station, such as the frequency of a radio signal transmitted by a peripheral base station, from a base station that is currently communicating, and determines whether or not the peripheral base station has been changed. (Step S100).

When it is determined that there has been a change (step S1)
(YES in 00), a list indicating the order in which the received signal strengths of the radio signals transmitted from each base station are measured is created (step S101), and the measurement of the received signal strength is started in the order according to the created list.

On the other hand, if it is determined that there has been no change (NO in step S100), it is determined whether the measurement of the received electric field strength has been completed (step S102), and if it has been determined that the measurement has been completed (YES in step S102). The list is changed so that when the next reception electric field strength is measured, the measurement is performed in order from the base station having the largest reception electric field strength in the current measurement (step S103).

If it is determined in step S102 that the measurement of the received electric field strength has not been completed (NO in step S102), the received electric field strength of the radio signal transmitted from the base station in the next order shown in the list is determined. Is measured, and the process returns to step S100 (step S104). By doing so, the next measurement is performed in order from the one with the largest received electric field strength as a result of the measurement,
It is possible to find a base station with good communication quality in a short time and switch the communication destination.

[0008]

However, in the above-mentioned conventional mobile communication terminal, since the next measurement order is determined based on only one measurement result, the base station has an instantaneously increased reception electric field strength. Also, the received electric field strength is measured preferentially in the next measurement. For this reason, there is a problem that wasteful time is required for the measurement and communication switching to another base station having good communication quality is delayed.

The present invention has been made in view of the above situation, and has as its object to provide a mobile communication terminal capable of efficiently switching a base station of a communication destination and a communication method thereof.

[0010]

In order to achieve the above object, a mobile communication terminal according to a first aspect of the present invention has a measuring means for measuring the reception electric field strength of radio signals transmitted from a plurality of base stations. And, a timer that specifies the time at which the measuring unit measures the received electric field strength, and the received electric field strength measured by the measuring unit, for each base station that transmits a radio signal,
A data storage unit that stores as time-series data corresponding to the time specified by the clock unit, and a function indicating a change in received electric field strength for each base station from the time-series data stored in the data storage unit. A strength change prediction means for predicting a change in received electric field strength for each base station from the specified function, and a scheduling means for causing the measuring means to measure the received electric field strength in an order based on the prediction result by the strength change prediction means are provided. , Characterized in that.

According to the present invention, the received electric field strength of the radio signal transmitted from the base station is stored as time series data, and the change of the received electric field strength for each base station is specified as a regression function from the time series data. Thus, a change in the received electric field strength can be predicted. In addition, the received electric field strength can be measured again in an order according to the result of estimating the change in the received electric field strength. As a result, a base station with good communication quality can be found in a short time, and the base station of the communication destination can be efficiently switched.

A mobile communication terminal according to a second aspect of the present invention measures the reception field strength of radio signals transmitted from a plurality of base stations every time the timing of measuring the reception field strength arrives. Measuring means, time measuring means for specifying the time at which the measuring means measured the received electric field strength, and the received electric field strength measured by the measuring means, for each base station transmitting the radio signal, the time specified by the time measuring means Data storage means for storing as time-series data corresponding to, and a function indicating a change in received electric field strength for each base station from the time-series data stored in the data storage means, and for each base station from the specified function The intensity change prediction means for predicting a change in the received electric field strength, and when the next timing at which the measuring means measures the received electric field strength arrives, the prediction change by the intensity change prediction means is performed. And a scheduling means for measuring a reception field strength in the order based on, characterized in that.

A storage control unit for controlling an operation of storing the time-series data in the data storage unit, wherein the storage control unit includes a reception electric field intensity measured by the measurement unit and a function specified by the intensity change prediction unit. It is determined whether or not the difference between the received electric field strengths predicted from the data storage means is larger than a predetermined permissible error amount. It is desirable to exclude from the time-series data when the intensity change prediction means obtains the function. Thereby, when the received electric field strength is increased instantaneously, etc., by treating the received electric field strength obtained by the measurement as an invalid measurement value, the received electric field strength is excluded from the time-series data used for obtaining the function, and the The prediction result can be obtained. Therefore, it is possible to prevent the communication destination from being switched to the base station whose communication quality is unstable, and to efficiently switch the communication destination base station.

More specifically, the intensity change predicting means includes:
Determining an allowable error amount based on a regression residual between the function specified from the time-series data stored in the data storage means and each measurement value included in the time-series data; and It is determined whether or not the difference between the received electric field strength measured by the function and the received electric field strength predicted from the function specified by the strength change predicting means is larger than the allowable error amount determined by the strength change predicting means. When it is determined, it is preferable that the received electric field strength measured by the measuring means is stored as an invalid measured value in the data storage means, and the received electric field strength is excluded from the time series data when the strength change predicting means obtains the function.

In some cases, the measured value of the received electric field strength required to obtain the function cannot be obtained due to frequent switching of the base station of the communication destination. Therefore, the intensity change prediction means, when it is not possible to predict the change of the received electric field strength for each base station from the time series data stored in the data storage means, from the time series data stored in the data storage means Find the average value of the time variation of the received electric field strength,
Based on the average value of the time variation of the received electric field strength,
It is desirable to specify and predict the change in the received electric field strength for each base station as a linear function.

Further, a communication method of a mobile communication terminal according to a third aspect of the present invention measures a reception electric field strength of a radio signal transmitted from a plurality of base stations, and measures the reception electric field strength for each base station. A first reception strength storage step of storing as series data, a regression calculation step of specifying a function indicating a change in reception field strength for each base station from the time series data stored in the first reception strength storage step, A prediction step of predicting a change in received electric field strength for each base station based on the function specified in the regression calculation step, and a scheduling step of defining an order of measuring the received electric field strength based on the predicted result; and A second step of measuring the received field strengths of the radio signals transmitted from the plurality of base stations in accordance with a prescribed order and storing the received field strength as time-series data for each base station; And a receiving intensity storing step,
It is characterized by the following.

According to the present invention, the received electric field strength of the radio signal transmitted from the base station is stored as time-series data,
From this time series data, it is possible to specify a change in the received electric field strength for each base station as a function. Further, it is possible to predict a change in the received field strength for each base station based on the specified function, and determine the order in which the received field strength is measured. As a result, a base station with good communication quality can be found in a short time, and the base station of the communication destination can be efficiently switched.

More specifically, in the scheduling step, a predicted value of the received electric field strength for each base station measured in the second received power storage step is calculated from the function specified in the regression operation step. It is desirable to define the order of measuring the received electric field strength so that the received electric field strength is measured from the radio signal transmitted from the base station whose calculated and predicted value is large.

Further, the regression calculation step includes the first regression calculation step.
And a step of specifying a function indicating a change in the received electric field strength for each base station from the time-series data stored in the second received strength storage step.

The second reception intensity storing step determines whether a difference between the measured reception electric field intensity and the reception electric field intensity predicted in the scheduling step is larger than a predetermined allowable error amount, and judges that the difference is large. Then, the measured reception field strength is stored as an invalid measurement value, and the regression calculation step excludes the measurement value of the reception field strength stored as an invalid measurement value in the second reception strength storage step. It is desirable to specify a function indicating a change in the received electric field strength for each base station. Thereby, when the received electric field strength is increased instantaneously, etc., by treating the received electric field strength obtained by the measurement as an invalid measurement value, the received electric field strength is excluded from the time-series data used for obtaining the function, and the The prediction result can be obtained. Therefore, it is possible to prevent the communication destination from being switched to the base station whose communication quality is unstable, and to efficiently switch the communication destination base station.

More specifically, the regression calculation step comprises:
Determining an allowable error amount from a regression residual between the function specified from the time-series data and each measurement value included in the time-series data, the second reception strength storage step includes: It is determined whether or not the difference between the received electric field strengths predicted in the above is larger than the allowable error amount determined in the regression calculation step, and if it is determined to be larger, the measured received electric field strength is stored as an invalid measured value. Is desirable.

In some cases, the measured value of the received field strength required to obtain the function cannot be obtained due to frequent switching of the base station of the communication destination. Therefore, the regression calculation step includes, when the change in the reception electric field strength for each base station cannot be specified from the time series data stored in the first and second reception strength storage steps, the first and second reception strengths. The average value of the time variation of the received electric field strength is obtained from the time-series data stored in the intensity storing step, and the change of the received electric field strength for each base station is calculated based on the average value of the obtained time variation of the received electric field strength. It is desirable to specify as a linear function.

Further, according to a communication method of a mobile communication terminal according to a fourth aspect of the present invention, the reception electric field strength of a radio signal transmitted from a plurality of base stations each time the reception electric field strength measurement timing arrives An intensity measuring step of measuring
A receiving strength storing step of storing the received electric field strength for each base station measured in the strength measuring step as time-series data associated with a measurement time; and a base station from the time-series data stored in the receiving strength storing step. A regression calculation step for specifying a function indicating a change in received electric field strength for each base station; a reception strength prediction step for predicting a change in received electric field strength for each base station based on the function specified in the regression calculation step; A scheduling step of defining a measurement order at the next timing of measuring the reception electric field strength in the measurement step based on the result predicted in the reception strength prediction step.

In the scheduling step, from the function specified in the regression calculation step, a predicted value of the received field strength for each base station at the next timing when the received field strength is measured in the strength measuring step is obtained. It is desirable to define the measurement order so that the received electric field strength is measured from the radio signal transmitted from the base station having the larger predicted value.

Further, the intensity measuring step includes an intensity difference determining step of determining whether a difference between the measured received electric field intensity and the received electric field intensity predicted in the scheduling step is larger than a predetermined allowable error amount. In the receiving strength storing step, when the difference between the measured receiving field strength and the predicted field strength is determined to be larger than the allowable error amount in the strength difference determining step, the measured receiving field strength is regarded as an invalid measurement value. Storing the regression calculation step,
It is desirable that the measured value of the received field strength stored as an invalid measured value in the reception strength storing step is excluded to specify a function indicating a change in the received field strength for each base station.

More specifically, the regression calculation step comprises:
Determine the allowable error amount from the regression residual between the function specified from the time-series data and each measurement value included in the time-series data, and the strength difference determination step is predicted by the measured reception field strength and the scheduling step. It is desirable to determine whether or not the difference between the received electric field strengths is larger than the allowable error amount determined in the regression calculation step.

[0027] The regression calculation step includes, when a change in the reception electric field strength for each base station cannot be specified from the time series data stored in the reception strength storage step, from the time series data stored in the reception strength storage step. It is desirable to determine the average value of the time change amount of the reception electric field strength, and to specify the change of the reception electric field strength for each base station as a linear function based on the obtained average value of the time change amount of the reception electric field strength.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a mobile communication terminal according to an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a configuration of a mobile communication terminal 100 according to an embodiment of the present invention. As illustrated, the mobile communication terminal 100 includes an antenna 1, a communication processing unit 2, a processing control unit 3, and a storage unit 4.

The communication processing unit 2 includes a frequency converter, a quadrature detector, an audio signal processing circuit, and the like. The communication processing unit 2 demodulates a radio signal received by the antenna 1 to extract an audio signal or a data signal, or a microphone (see FIG. A wireless signal is modulated in accordance with an audio signal input from the antenna controller (not shown) or a data signal received from the processing controller 3 and transmitted from the antenna 1. The communication processing unit 2 includes a reception strength measurement unit 10 and a base station information extraction unit 11
And

The reception intensity measuring unit 10 is provided with a PN (Pseudo Noi
se) It is composed of a sequence generator, a correlator, an integrator, etc., measures the received electric field strength of radio signals received from a plurality of base stations for each base station under the control of the measurement control unit 22, and receives the result. Notify.

The base station information extracting section 11 is composed of a decoder and the like, extracts base station information, which is information on peripheral base stations, from a radio signal received by the antenna 1 and sends it to the reception result processing section 21.

The processing control unit 3 includes a CPU (Central Processes).
sing unit), and the mobile communication terminal 10
0 for controlling the operation of the whole
, A reception result processing unit 21, a measurement control unit 22, a regression calculation processing unit 23, and a calculation result processing unit 24.

The timer 20 specifies the time when the reception strength measurement unit 10 measures the reception electric field strength of the radio signal as the relative time between the previous measurement and the current measurement for each base station.

The reception result processing unit 21 includes the reception intensity measurement unit 1
The base station list 50 that defines the order in which the received signal strengths are measured is created based on the measured received signal strengths of the radio signals for each base station.

FIG. 2 is a diagram showing an example of the base station list 50. As shown in the figure, the base station list 50 records the base station identification data for identifying the base station whose reception field strength is to be measured by the reception strength measurement unit 10 in order, and the reception strength measurement unit 10 Specifies the order in which the electric field strength is measured. Here, base station identification data is various information for identifying a base station transmitting a radio signal, for example,
It contains the ID number of the base station, the frequency of the radio signal to be transmitted, the spreading pattern of the spreading code, and the like. Receive result processing unit 21
Creates base station identification data from the base station information extracted by the base station information extraction unit 11 and records it in the base station list 50. Further, the base station list 50 records the predicted value of the received electric field strength and the allowable error amount for each base station obtained by the regression operation processing unit 23 described later in association with the base station identification data.

The reception result processing unit 21 records the received electric field intensity measured by the reception intensity measurement unit 10 together with the measurement time specified by the timer unit 20 in the storage unit 4 for each base station, to obtain time-series data. , A reception intensity table 51 as shown in FIG.

At this time, the reception result processing section 21 determines whether or not the difference between the measured value of the received field strength measured by the received strength measuring section 10 and the predicted value recorded in the base station list 50 is larger than the allowable error amount. Is determined. When the reception result processing unit 21 determines that the difference between the actual measurement value and the prediction value is larger than the allowable error amount, the reception result processing unit 21 determines that the actual measurement value of the reception electric field strength measured by the reception intensity measurement unit 10 is an invalid actual measurement value, and If it is determined that it is equal to or less than the amount, it is determined that this is a valid actual measurement value. The reception result processing unit 21 records in the reception intensity table 51 so that the measured reception electric field intensity can be identified as a valid actual value or an invalid actual value.

The reception intensity table 51 records the actual measured value of the reception electric field intensity of the radio signal together with the measurement time specified by the timer 20 for each base station.
3 makes it possible to predict the received electric field strength for each base station in the next measurement.

The measurement control unit 22 controls the reception strength measurement unit 10 to receive the reception electric fields of radio signals transmitted from a plurality of base stations in the order specified by the base station list 50 stored in the storage unit 4. The intensity is measured at predetermined time intervals.

The regression calculation processing unit 23 performs a regression analysis based on the actually measured value of the received electric field strength for each base station recorded in the received strength table 51 and the measurement time when the measurement was performed. , A function (regression function) indicating a change in the received electric field strength is obtained. At this time, the regression calculation processing unit 23
When the measured value of the received electric field strength recorded in the received strength table 51 is invalid, a regression function is obtained from other measured values excluding the measured value. Regression calculation processing unit 23
Calculates the predicted value of the received electric field strength for each base station in the next measurement using the obtained regression function. Further, the regression calculation processing unit 23 calculates a regression residual between a regression function and an actually measured value of the reception electric field strength recorded in the reception strength table 51, and the like.
An allowable error amount between the actually measured value and the predicted value of the received electric field strength in the next measurement is obtained. The predicted value of the received electric field strength and the allowable error amount thus obtained are sent to the calculation result processing unit 24.

The operation result processing unit 24 is a regression operation processing unit 2
3 for receiving the predicted value of the received electric field strength and the allowable error amount from the base station list 3, and changing the description of the base station list 50 so as to perform scheduling so that the measurement is performed in order from the base station having the larger predicted value in the next measurement. It is.

The storage unit 4 has a ROM (Read Only Memory)
y), RAM (Random Access Memory) and EEPRO
M (Electronically Erasable and Programmable ROM)
And the like, and records a program that defines the operation of the processing control unit 3. The storage unit 4 stores the base station list 50 and the reception strength table 51 created by the reception result processing unit 21.

The operation of mobile communication terminal 100 according to the embodiment of the present invention will be described below. The mobile communication terminal 100 predicts a change in the received electric field strength for each base station from the measured received electric field strength, and sequentially measures the radio signals transmitted from the base station predicted to have good communication quality, The connection destination base station can be switched efficiently.

First, the mobile communication terminal 100 communicates with the communication service area A covered by the base station Bs as shown in FIG.
r, the mobile station transmits and receives radio signals to and from the base station Bs to activate a standby channel or a communication channel, thereby enabling communication with another telephone device or data communication. .

Further, the mobile communication terminal 100 receives, from the destination base station Bs, information on the peripheral base station Bs, for example, information such as the ID number of the base station Bs and the frequency of the radio signal to be transmitted. The reception electric field strength of the radio signal received from each base station Bs is measured.

At this time, the mobile communication terminal 100 executes a process as shown in the flowchart of FIG.

That is, when the mobile communication terminal 100 receives a radio signal from the base station Bs of the communication destination, the base station information extracting unit 11 extracts the base station information on the neighboring base station Bs, and executes the reception result processing unit 21. Send to Receive result processing unit 21
Determines whether the base station information received from the base station information extracting unit 11 includes information on a new base station Bs, that is, whether there is a change in a neighboring base station Bs (step S1). .

[0049] The reception result processing section 21 transmits the information to the neighboring base station Bs.
Is determined to have been changed (YE in step S1).
S), the base station list 50 is created by, for example, adding the base station Bs indicated in the base station information received from the base station information extraction unit 11 to the base station list 50, and measurement of the received electric field strength is started (step S). S2).

On the other hand, if the reception result processing section 21 determines that there is no change in the surrounding base station Bs (NO in step S1), it skips the processing in step S2, advances the processing to step S3, and proceeds to step S3. It is determined whether the measurement of the received electric field strength of the radio signal transmitted from the base station Bs recorded in the station list 50 has been completed (step S).
3).

When the reception result processing section 21 determines that the measurement has been completed (YES in step S3), it controls the regression calculation processing section 23 to measure the actual measured value of the reception electric field strength recorded in the reception strength table 51. And its measurement time,
Perform regression analysis.

The regression operation processing section 23 controls each base station Bs for which base station identification data is recorded in the reception strength table 51.
, The actual measured value of the received electric field strength and the measurement time are read for each base station Bs, and each base station B in the next measurement is read.
A predicted value of the received electric field strength of the wireless signal of s is obtained (step S4).

More specifically, the regression operation processing unit 23
A regression function is obtained by a least-squares method or the like from the actually measured value of the received electric field strength for each base station Bs recorded in the received intensity table 51, and from the obtained regression function and the timing at which the next measurement is performed, the next measurement is performed. Obtain a predicted value of the received electric field strength. Here, the timing at which the next measurement is performed depends on the magnitude of the received electric field strength of the radio signal transmitted from the base station Bs of the communication destination, whether or not the surrounding base station Bs has been changed, and whether or not the base station Bs of the communication destination has changed. Is determined immediately after switching, and in the case where the base station Bs of the communication destination is switched, it is further determined based on whether the communication carrier managing the base station Bs is the same before and after the switching. .

Further, the regression calculation processing section 23 obtains an allowable error amount of the received electric field strength in the next measurement from the regression residual between the obtained regression function and each measured value.

At this time, the regression operation processing section 23 obtains a regression function from the measured values of the received electric field strength recorded in the received strength table 51 which are recorded as effective measured values.

Further, when the base station list 50 is frequently changed, the number of actually measured values recorded in the reception intensity table 51 may be smaller than the number required for executing the regression analysis. In such a case, the regression calculation processing unit 23 calculates the average value of the time variation of the received electric field intensity from the actually measured value recorded in the received intensity table 51,
A linear function may be created using the average value of the time change amount and the actual measurement value of the first measurement recorded in the reception intensity table 51. The regression calculation processing unit 23 can obtain a predicted value of the received electric field intensity in the next measurement by using the created linear function as a regression function.

The regression calculation processing section 23 distinguishes the predicted value of the received electric field strength and the allowable error amount in the next measurement obtained in this manner for each base station Bs and sends them to the calculation result processing section 24.

The operation result processing unit 24 is a regression operation processing unit 2
When receiving the predicted value of the received electric field strength and the allowable error amount from 3,
The predicted value of the received electric field strength is compared for each base station Bs, and the description of the base station list 50 is changed so that the received electric field strength is measured in the next measurement in order from the base station Bs having the largest predicted value (step S5) . For example, the calculation result processing unit 2
No. 4 records the base station identification data for identifying each base station Bs and the predicted value of the received electric field strength in the base station list 50 in descending order of the predicted value. Calculation result processing unit 24
Stores the changed base station list 50 in the storage unit 4 and enables the measurement control unit 22 to read the base station list 50.

The measurement control unit 22 reads the base station list 50 recorded in the storage unit 4 and
To measure the received field strength for each base station Bs according to the order shown in the base station list 50. The reception intensity measurement unit 10 measures the reception electric field intensity for each base station Bs according to the order shown in the base station list 50 by, for example, adjusting the synchronization frequency under the control of the measurement control unit 22. Notify (step S6).

The reception result processing unit 21 is provided with the reception intensity measurement unit 1
When the measured value of the received electric field strength is notified from 0, it is compared with the predicted value of the received electric field strength shown in the base station list 50, and the difference is obtained. The reception result processing unit 21 determines that the difference between the actually measured value and the predicted value of the received electric field strength is the base station list 5.
It is determined whether or not it is larger than the allowable error amount indicated by 0 (step S7).

When the reception result processing unit 21 determines that the difference between the actually measured value and the predicted value of the received electric field strength is larger than the allowable error amount (NO in step S7), the reception electric field The measured value of the intensity is recorded in the reception intensity table 51 as an invalid measured value (step S
8). The actual measured value of the received electric field intensity recorded as an invalid actual measured value in the received intensity table 51 is used as data for obtaining a regression function when the regression operation processing unit 23 performs regression analysis in step S4. Not done. Therefore, when the actual measured value is significantly different from the predicted value, the actual measured value can be excluded and the received electric field strength in the next measurement can be predicted, and even if the received electric field intensity changes instantaneously, A reasonable prediction result can be obtained.

On the other hand, when the reception result processing unit 21 determines that the difference between the actually measured value and the predicted value of the received electric field strength is equal to or smaller than the allowable error amount (YES in step S7), the reception result processing unit 21 notifies the reception result processing unit 21. The measured value of the received electric field strength is recorded as a valid measured value in the received strength table 51 (step S9). The actual measured value of the received electric field intensity recorded as an effective measured value in the received intensity table 51 is used as data for obtaining a regression function when the regression operation processing unit 23 performs a regression analysis in step S4. Is done.

Thereafter, the process returns to the above-described step S 1, and each time the timing for starting the next measurement comes, the reception electric field strength of the radio signal transmitted from the neighboring base station Bs is added to the base station list 50. Measure in the order shown.

Next, as a specific example, three base stations B1 to B1
The operation of mobile communication terminal 100 when the received electric field strength of the radio signal transmitted from B3 changes as shown in FIG. 6 will be described. Here, the mobile communication terminal 100
Is to measure the received electric field strength at timings t1 to t4 shown in FIG. Further, in this example, it is assumed that the regression calculation processing unit 23 obtains a primary regression curve (regression line) from two actually measured values for each of the base stations B1 to B3.

In this case, after the end of the measurement at the timing t1, the regression operation processing section 23 reads the reception intensity table 51 and predicts the reception electric field intensity in the next measurement for each of the base stations B1 to B3. At the time when the measurement at the timing t1 is completed, the reception intensity table 51 indicates that each base station B
Since there is only one actually measured value of the received electric field strengths 1 to B3, the regression calculation processing unit 23 sends the measurement result at the timing t1 as it is to the calculation result processing unit 24 as a predicted value as in the related art.

The operation result processing unit 24 is provided with the regression operation processing unit 2
3, and the description of the base station list 50 is changed so that the next predicted value is measured from the one with the larger predicted value.

As shown in FIG. 6, at timing t1,
The received electric field strength of the base station B1 is the largest, and the received electric field strength of the base station B3 is the smallest. Therefore, the calculation result processing unit 2
No. 4 changes the description of the base station list 50 so that the received electric field strength is measured in the order of the base stations B1, B2, and B3 in the next measurement.

Next, after completion of the measurement at the timing t2, the regression operation processing section 23 reads the reception intensity table 51 and predicts the reception electric field intensity in the next measurement for each of the base stations B1 to B3.

At the time when the measurement at the timing t2 is completed, the measured values of the received electric field strengths of the base stations B1 to B3 at the timings t1 and t2 are stored in the reception strength table 51.
Recorded together with the measurement time. Therefore, the regression operation processing unit 23 sets the timing t1 and the timing t1 for each of the base stations B1 to B3.
From the measured value of the received electric field strength at t2 and the measurement time, the slope, intercept and the like of the received electric field strength are obtained, and a regression line as shown by a thick line in FIG. 7 is obtained. The regression calculation processing unit 23 obtains a predicted value of the received electric field strength at the timing t3 for each of the base stations B1 to B3 from the obtained regression line, and sends it to the calculation result processing unit 24.

As shown in FIG. 7, the predicted value of the received electric field strength at the timing t3 is the largest for the base station B1.
Base station B2 is the smallest. Therefore, the regression operation processing unit 23
Changes the description of the base station list 50 so that the received electric field strength is measured in the order of the base stations B1, B3, and B2 in the next measurement.

Next, after completion of the measurement at the timing t3, the regression calculation processing section 23 reads the reception intensity table 51 and predicts the reception electric field intensity in the next measurement for each of the base stations B1 to B3. For example, the regression operation processing unit 23
FIG. 8 shows the reception electric field strengths of the base stations B1 to B3 at the timings t1 to t3 recorded in the reception intensity table 51 at the time when the measurement at the timing t3 is completed, and the measurement times thereof, as shown by the thick line in FIG. Find such a regression line.

The regression operation processing unit 23 obtains a predicted value of the received electric field intensity at the timing t4 for each of the base stations B1 to B3 from the obtained regression line, and sends it to the operation result processing unit 24. At this time, the regression operation processing unit 23 determines the allowable error amount of the received electric field strength at the timing t4 based on the deviation between the obtained regression function and the actually measured value, that is, the regression residual.
It is obtained for each of 1 to B3 and sent to the calculation result processing unit 24.

As shown in FIG. 8, the predicted value of the received electric field strength at the timing t4 is the largest for the base station B3.
Base station B2 is the smallest. Therefore, the regression operation processing unit 23
Changes the description of the base station list 50 so that the received field strength is measured in the order of the base stations B3, B1, and B2 in the next measurement.

Thereafter, in the measurement at the timing t4, since the measured value of the received electric field strength of the radio signal transmitted from the base station B2 is significantly different from the predicted value, the reception result processing section 21 sets the base station B2 The measured value of the received electric field strength is recorded in the received strength table 51 as invalid.

In the regression analysis after the end of the measurement at the timing t4, the regression operation processing unit 23 determines that the actual measured value of the received electric field strength at the timing t4 of the base station B2 is invalid. The next received electric field strength is predicted using the value, and an allowable error amount is obtained. Thus, when the received electric field strength increases instantaneously due to Rayleigh fading or the like, by treating this as an invalid measurement value, it can be excluded from the processing for determining the next measurement order. Therefore, it is possible to prevent the communication destination from being switched to the base station whose communication quality is unstable, to efficiently switch the communication destination base station, secure stable communication quality, and reduce power consumption. In addition, since a base station having good communication quality can be quickly found, the number of unnecessary handovers and control message transmission / reception can be reduced, and the load on the mobile communication system can be reduced.

As described above, according to mobile communication terminal 100, the actual measured value of the received electric field strength of the radio signal transmitted from the base station is recorded, and the received electric field strength in the next measurement is determined by regression analysis. Can be calculated. Then, by measuring the received field strength in order from the one with the largest predicted value, a base station with good communication quality can be quickly found, and the base station of the communication destination can be switched efficiently.

The present invention is not limited to the above embodiment, and various modifications and applications are possible. For example, in the above-described embodiment, when the difference between the measured value and the predicted value of the received electric field strength is larger than the allowable error amount, only the invalid measured value is recorded in the reception strength table 51. It is not limited to. That is, for example, when it is determined that the measured values are invalid measured values continuously for a predetermined number of times, or when the number of invalid measured values recorded in the reception strength table 51 for each base station is larger than the number of valid measured values. If the number increases, regression analysis may be performed using invalid measured values to obtain the predicted value of the received electric field strength and the allowable error amount.
As a result, even when the effective measured value is a special value, it is possible to perform appropriate prediction of the received electric field strength and efficiently switch the base station of the communication destination.

Further, in the above-described embodiment, when estimating the received electric field intensity, the regression line is calculated. However, the present invention is not limited to this. A regression function of an arbitrary order may be calculated.

In the above embodiment, the reception electric field intensity table 51 is described as recording the received electric field intensity so that the measured reception electric field intensity can be identified as a valid actual value or an invalid actual measured value. A table for recording only actual measured values and a table for recording only invalid actual values may be provided separately.

The mobile communication terminal according to the present invention can be realized by using, for example, a normal mobile communication terminal functioning as a mobile phone, without being configured as a dedicated terminal. That is, a medium (ROM or the like) storing a program for executing the above-described processing in a normal mobile communication terminal
And the program is executed on a terminal, whereby the terminal can function as the mobile communication terminal of the present invention. Further, a program for executing the above-described processing is transferred from an external medium to a medium (EEPROM) in the terminal via a communication connector or the like provided in a normal mobile communication terminal.
Etc.) and executed on the terminal.

[0081]

As described above, according to the present invention, the measured value of the received electric field strength of the radio signal transmitted from the base station is stored together with the measurement time, and the regression analysis is performed using these values. Then, the received electric field strength in the next measurement can be predicted, and the received electric field strength can be measured in ascending order of the predicted value. As a result, a base station with good communication quality can be found in a short time, and the base station to be contacted can be efficiently switched.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a mobile communication terminal according to an embodiment of the present invention.

FIG. 2 is a diagram showing a base station list.

FIG. 3 is a diagram showing a reception strength table.

FIG. 4 is a diagram showing a state of communicating with a base station for explaining an operation of the mobile communication terminal according to the embodiment of the present invention.

FIG. 5 is a flowchart for explaining an operation of the mobile communication terminal according to the embodiment of the present invention.

FIG. 6 is a diagram showing a change in received electric field strength in a specific example of the operation of the mobile communication terminal.

FIG. 7 is a diagram illustrating a result of a regression analysis in a specific example of the operation of the mobile communication terminal.

FIG. 8 is a diagram illustrating a result of a regression analysis in a specific example of the operation of the mobile communication terminal.

FIG. 9 is a flowchart illustrating an operation of a conventional mobile communication terminal.

[Explanation of symbols]

 Reference Signs List 1 antenna 2 communication processing unit 3 processing control unit 4 storage unit 10 reception strength measurement unit 11 base station information extraction unit 20 clock unit 21 reception result processing unit 22 measurement control unit 23 regression calculation processing unit 24 calculation result processing unit 50 base station list 51 reception strength table 100 mobile communication terminals B1 to B3, Bs base station As communication service area

Claims (16)

[Claims] 1. A measuring means for measuring a received electric field strength of a radio signal transmitted from a plurality of base stations; a time measuring means for specifying a time at which the measuring means measured the received electric field strength; A data storage unit that stores the received electric field strength as time-series data corresponding to the time specified by the time-measuring unit for each base station that transmits a radio signal; and a base station that stores the time-series data stored in the data storage unit. Identify a function that indicates the change in received field strength for each station,
A strength change predicting unit for predicting a change in received electric field strength for each base station from the specified function, and a scheduling unit for causing the measuring unit to measure the received electric field strength in an order based on a prediction result by the strength change predicting unit. A mobile communication terminal, characterized in that: 2. A measuring means for measuring the received electric field strength of radio signals transmitted from a plurality of base stations each time a timing for measuring the received electric field strength arrives, and a time at which the measuring means measures the received electric field strength. A data storage unit that stores the received electric field strength measured by the measurement unit as time-series data corresponding to the time specified by the clock unit for each base station that transmits a radio signal. From the time-series data stored in the data storage means to identify a function indicating a change in received electric field strength for each base station,
Strength change prediction means for predicting a change in received electric field strength for each base station from the specified function, and when the next timing at which the measurement means measures the received electric field strength arrives, based on the prediction result by the strength change prediction means A mobile communication terminal, comprising: scheduling means for measuring received electric field strength in order. 3. A storage control means for controlling an operation of storing time-series data in said data storage means, wherein said storage control means specifies a received electric field strength measured by said measurement means and said strength change prediction means. It is determined whether or not the difference in the received field strength predicted from the function obtained is larger than a predetermined allowable error amount. The mobile communication terminal according to claim 1, wherein the mobile communication terminal is stored in a storage unit, and is excluded from time-series data when the intensity change prediction unit obtains a function. 4. The method according to claim 1, wherein the intensity change predicting means determines an allowable error amount based on a regression residual between a function specified from the time series data stored in the data storage means and each measurement value included in the time series data. The storage control unit determines the difference between the reception electric field intensity measured by the measurement unit and the reception electric field intensity predicted from the function specified by the intensity change prediction unit. It is determined whether or not the magnitude is larger than the amount.If it is determined that the magnitude is greater, the received electric field strength measured by the measuring means is stored as an invalid measurement value in the data storage means, and the strength change predicting means obtains the function The mobile communication terminal according to claim 3, wherein the mobile communication terminal is excluded from the time series data. 5. The method according to claim 1, wherein the change in the received electric field intensity is not stored in the data storage unit when the change in the received electric field intensity for each base station cannot be predicted from the time series data stored in the data storage unit. The average value of the time variation of the reception electric field strength is obtained from the sequence data, and the change of the reception electric field strength for each base station is specified and predicted as a linear function based on the obtained average value of the time variation of the reception electric field strength. The mobile communication terminal according to any one of claims 1 to 4, characterized in that: 6. A first reception strength storing step of measuring reception field strengths of radio signals transmitted from a plurality of base stations and storing the received field strengths as time-series data of the reception field strengths for each base station; A regression calculation step for specifying a function indicating a change in the reception field strength for each base station from the time-series data stored in the reception strength storage step; and a reception field for each base station based on the function specified in the regression calculation step. A scheduling step of predicting a change in strength and measuring an order of measuring the received electric field strength based on the predicted result; and a receiving electric field of a radio signal transmitted from a plurality of base stations in accordance with the order defined in the scheduling step. A second reception intensity storing step of measuring the intensity and storing it as time-series data for each base station. Communication method of the communication terminal. 7. The scheduling step obtains a predicted value of the received electric field intensity for each base station measured in the second reception intensity storage step from the function specified in the regression operation step. The communication method according to claim 6, wherein an order of measuring the received electric field strength is defined so as to measure the received electric field strength from a radio signal transmitted from a base station having a large predicted value. 8. The regression calculation step includes a step of specifying a function indicating a change in received field strength for each base station from the time-series data stored in the first and second received strength storage steps. The communication method according to claim 6, wherein: 9. The second reception strength storage step determines whether a difference between the measured reception field strength and the reception field strength predicted in the scheduling step is larger than a predetermined allowable error amount, and determines whether the difference is larger. Is determined, the measured received field strength is stored as an invalid measured value, and the regression calculation step excludes the measured value of the received field strength stored as an invalid measured value in the second receiving strength storage step. The communication method according to claim 8, wherein a function indicating a change in received electric field strength for each base station is specified. 10. The regression calculation step determines an allowable error amount from a regression residual between a function specified from time-series data and each measurement value included in the time-series data. It is determined whether or not the difference between the measured reception field strength and the reception field strength predicted in the scheduling step is larger than the allowable error amount determined in the regression calculation step. The communication method according to claim 9, wherein the field strength is stored as an invalid measurement value. 11. The regression calculation step includes the steps of: when the change in the received electric field strength for each base station cannot be specified from the time series data stored in the first and second received strength storage steps, The average value of the time variation of the reception electric field strength is obtained from the time-series data stored in the reception intensity storage step 2 and the reception electric field strength of each base station is determined based on the average value of the time variation of the reception electric field strength obtained. The communication method according to any one of claims 6 to 10, wherein a change in the value is specified as a linear function. 12. An intensity measuring step of measuring the received electric field strength of radio signals transmitted from a plurality of base stations each time a timing of measuring the received electric field strength arrives, and a base station measured in the intensity measuring step. A reception intensity storing step of storing the reception electric field intensity for each station as time-series data associated with the measurement time, and a function indicating a change in the reception electric field intensity for each base station from the time-series data stored in the reception intensity storage step A regression calculation step of specifying the following; a reception strength prediction step of predicting a change in a reception field strength for each base station based on the function specified in the regression calculation step; and a reception field strength measured in the strength measurement step. A scheduling step for defining the measurement order at the next timing based on the result predicted in the reception strength prediction step. A communication method for a mobile communication terminal, comprising: 13. The scheduling step obtains, from the function specified in the regression operation step, a predicted value of the received electric field intensity for each base station at the next timing when the received electric field intensity is measured in the intensity measuring step. The measurement order is defined so as to measure the received electric field strength from the radio signal transmitted from the base station having the obtained predicted value large.
The communication method according to claim 12, wherein: 14. The strength measuring step includes a strength difference determining step of determining whether a difference between the measured received field strength and the received field strength predicted in the scheduling step is larger than a predetermined allowable error amount. The reception strength storage step, when the difference between the measured reception field strength and the predicted field strength is determined to be larger than the allowable error amount in the strength difference determination step, the measured reception field strength as an invalid measurement value. The regression calculation step specifies a function indicating a change in the reception field strength for each base station by excluding the measurement value of the reception field strength stored as an invalid measurement value in the reception strength storage step, 14. The communication method according to claim 12, wherein: 15. The regression calculating step determines an allowable error amount from a regression residual between a function specified from the time-series data and each measurement value included in the time-series data. The method according to claim 14, wherein it is determined whether a difference between the received electric field strength and the received electric field strength predicted in the scheduling step is larger than an allowable error amount determined in the regression operation step. Communication method. 16. The method according to claim 1, wherein the regression calculation step includes the step of storing the time series stored in the reception strength storage step when a change in the reception electric field strength for each base station cannot be specified from the time series data stored in the reception strength storage step. An average value of the time variation of the received electric field strength is obtained from the data, and the change of the received electric field strength for each base station is specified as a linear function based on the obtained average value of the time variation of the received electric field strength. The communication method according to any one of claims 12 to 15, wherein