JP2007116282A - Portable terminal and communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile portable terminal for executing cell selection processing that properly selects a cell with excellent reception quality. <P>SOLUTION: The portable terminal for making communication with a network via a base station for managing in-zone cells includes: a received quality calculation section for measuring first received quality of a received signal for a prescribed period and calculating second received quality of the received signal on the basis of the first received quality measured within a first period; a cell selection section for selecting a cell from which a signal with the excellent second received quality is transmitted on the basis of the second received quality calculated by the received quality calculation section; a speed discrimination section for discriminating the mobile speed of the portable terminal; and a period change section for changing the length of the first period on the basis of the mobile speed discriminated by the speed discrimination section. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a mobile terminal and a communication method for communicating with a network via a base station that manages a serving cell.

 In general, in mobile communication systems, mobile terminals in multiple cells calculate the reception quality of signals received from each cell, and select the cell with the best reception quality based on the calculated reception quality Cell selection processing to be performed.

 In such a mobile communication system, the mobile terminal performs a handover process in which the cell selected in the cell selection process described above is changed to a serving cell, and appropriately changes the serving cell to a cell with good reception quality. Is configured to change.

  Specifically, cell selection processing performed by the mobile terminal will be described with reference to FIG.

  For example, the mobile terminal measures the reception power of the signal received from each cell for each cell at the reception quality measurement period T1 as shown in FIG. 9, and the measurement result is the reception quality of the signal received from each cell. (Hereinafter referred to as first reception quality).

  The first reception quality described above may vary due to the influence of surrounding buildings and the like.

  Therefore, the mobile terminal calculates the average value of the plurality of first reception qualities measured within the reception quality calculation period T2 as shown in FIG. Quality).

  Then, the mobile terminal selects a cell having the best reception quality of the received signal based on the acquired second reception quality.

As described above, in the cell selection process described above, the mobile terminal performs the first calculation at the time of calculation A based on the plurality of first reception qualities measured in the immediately preceding reception quality calculation period T2a as shown in FIG. 2 is calculated, and a cell having the best signal reception quality is selected based on the calculated second reception quality.
JP-A-7-38950

  However, the conventional mobile terminal has a problem that it does not appropriately select a cell with good reception quality in the above-described cell selection process.

  For example, as shown in FIG. 10, when a conventional mobile terminal moves over a plurality of cells from a point a to a point b where a cell with good reception quality is a cell c during the reception quality calculation period T2b. The second reception quality may be calculated based on the first reception quality measured in the cell a or the cell b. If the second reception quality is good in the cell selection process described above, the mobile terminal does not select the cell c as the cell with the best reception quality, and does not select the cell a or the cell b. In some cases, it was selected as the best cell.

  Therefore, the present invention has been made in view of the above points, and provides a mobile terminal and a communication method for performing cell selection processing for appropriately selecting a cell having good reception quality in a mobile terminal that moves. With the goal.

 A first feature of the present invention is a mobile terminal that communicates with a network via a base station that manages a serving cell, and measures a first reception quality of a received signal at a predetermined period, Based on the first reception quality measured within the first period, a reception quality calculation unit that calculates a second reception quality of the received signal; and the second quality calculated by the reception quality calculation unit Based on reception quality, a cell selection unit that selects a cell in which the signal having good second reception quality is transmitted, a speed determination unit that determines a moving speed of the mobile terminal, and the speed determination unit And a period changing unit that changes the length of the first period based on the moving speed determined by the above.

 According to this invention, since the period changing unit can change the first period for calculating the second reception quality based on the moving speed determined by the speed determining unit, the mobile terminal moves. In addition, the cell selection unit can appropriately select a cell with good reception quality.

  Further, in the first feature of the present invention, the apparatus further comprises a cell change count detection unit for detecting the change count of the serving cell, wherein the rate determination unit is configured to detect the cell change count detection unit within the second period. The moving speed may be determined based on the number of changes of the serving cell detected in step (1).

  The first feature of the present invention may further include a position detection unit that detects position information of the mobile terminal, and the speed determination unit is detected by the position detection unit within the second period. The moving speed of the mobile terminal may be determined based on the position information.

  In the first aspect of the present invention, the period changing unit may change the length of the second period based on the moving speed determined by the speed determining unit.

  In the first aspect of the present invention, the period changing unit may change a cycle for measuring the first reception quality based on the moving speed determined by the speed determining unit.

  A second feature of the present invention is a communication method in which a mobile terminal communicates with a network via a base station that manages a serving cell, and includes a step A for determining a moving speed of the mobile terminal, Step B for determining the first period based on the determined moving speed, Step C for measuring the first reception quality of the received signal at a predetermined period, and measurement in the first period. Step D for calculating the second reception quality of the received signal based on the first reception quality, and the second reception quality based on the second reception quality calculated in Step D Based on the notification from the base station, the step F for selecting a cell in which the signal having a good signal is transmitted, the step F for notifying the base station of the cell selected in the step E, The service cell is designated as step E. And summarized in that comprising the steps G to change selected the cell.

  According to this invention, the mobile terminal can change the first cell in step B and can change the serving cell to the second cell with good reception quality selected in step E. it can.

  As described above, according to the present invention, it is possible to provide a mobile terminal and a communication method for performing a cell selection process for appropriately selecting a cell with good reception quality in a mobile terminal that moves.

(Configuration of portable terminal according to the first embodiment of the present invention)
The configuration of the mobile terminal 10 according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 6.

 The mobile terminal 10 is configured to receive a signal from a cell in which the mobile terminal is present.

 The mobile terminal 10 is configured to communicate with a network via a base station that manages the serving cell.

 In addition, when the mobile terminal 10 is notified from the base station to change the serving cell to a specific cell, the mobile terminal 10 is configured to perform a handover process for changing the serving cell to the specific cell. Has been.

 FIG. 1 is a block diagram showing the configuration of the portable terminal 10. As shown in FIG. 1, the mobile terminal 10 includes a reception quality measurement unit 11, a cell selection unit 12, a handover number detection unit 13, a position detection unit 14, a speed determination unit 15, and a period change unit. 16.

 The reception quality measurement unit 11 is configured to measure the first reception quality for each cell of the signal received from the cell in which the mobile terminal 10 is present at the reception quality measurement period T1 shown in FIG.

 Here, in this embodiment, a case where the reception quality measurement period T1 is set to 2.5 sec will be described as an example. The reception quality measurement period T1 may be set between 2 seconds and 3 seconds.

 Further, the first reception quality measured by the reception quality measuring unit 11 is RSSI (Received Signal Strength Indicator) indicating the intensity of the received radio wave of the signal transmitted from each base station, and desired wave received power. RSCP (RSCP: Received Signal Code domain Power), Eo / Io (RSCP / RSSI), which is the sum of radio field intensity transmitted from multiple base stations, and the ratio of the desired signal received power and the interference signal received power. SIR (SIR: Signal Interference Ratio) may be used.

 The reception quality measuring unit 11 is configured to acquire the first reception quality converted into a power value when the measured result is a decibel value (dB).

 Further, the reception quality measuring unit 11 performs the second reception for each cell by a predetermined calculation method based on the plurality of first reception qualities measured within the reception quality calculation period T2 as shown in FIG. It is configured to calculate quality.

 Here, the predetermined reception quality calculation period T2 is a period longer than at least the reception quality measurement period T1, and in this embodiment, a case where it is set to 20 sec will be described as an example. The reception quality calculation period T2 may be set to a time between 5 and 10 times the reception quality measurement period T1.

Furthermore, the predetermined calculation method for calculating the second reception quality is an arithmetic average represented by the following formula (1) when the total number of the first reception quality X measured within the reception quality calculation period T2 is n. Or the geometric mean shown to the following (2) formula, the harmonic average shown to the following (3) formula, etc. may be sufficient.

 The cell selection unit 12 is configured to select a cell having the second best reception quality based on the second reception quality calculated for each cell by the reception quality measurement unit 11.

 In addition, the cell selection unit 12 is configured to notify the identification information of the cell selected by the cell selection process to the base station that manages the serving cell of the mobile terminal 10.

 The handover number detection unit 13 is configured to detect the number of handover processes in which the mobile terminal 10 changes a serving cell to a specific cell.

 The position detector 14 is configured to detect the position of the mobile terminal 10.

 Specifically, the position detection unit 14 may be configured by a GPS (Global Positioning System) function, a function for calculating position information based on distances from a plurality of wireless stations in the PHS network, and the like.

 The speed determination unit 15 includes a handover count-speed correspondence table as shown in the example of FIG. 3, and determines the number of handovers detected by the handover count detection unit 13 within the speed determination period T3 shown in FIG. On the basis of this, the moving speed of the mobile terminal 10 is determined with reference to the handover frequency-speed correspondence table.

 Specifically, the speed determination unit 15 refers to the handover number-speed correspondence table as shown in the example of FIG. 3 based on the number of handovers detected by the handover number detection unit 13 within the speed determination period T3. The moving speed of the mobile terminal 10 is determined to be low when it is 0 to 3 times, determined to be medium when it is 4 to 5 times, and determined to be high when it is 6 times or more. Has been.

 Here, the speed determination period T3 is a period longer than at least the reception quality calculation period T2, and in this embodiment, the case where the speed determination period T3 is set to 120 sec will be described as an example. Further, the speed determination period T3 may be set to a time between 2 and 10 times the reception quality calculation period T2.

 The speed determination unit 15 is configured to determine the moving speed of the mobile terminal 10 based on the change in the position of the mobile terminal 10 detected by the position detection unit 14 within the speed determination period T3. May be.

 Specifically, the speed determination unit 15 replaces the column of the number of handovers N corresponding to low speed from 0 m to L1 m in the handover number-speed correspondence table shown in the example of FIG. A distance-speed correspondence table (not shown) is provided in which the number N column is replaced from L1m to L2m, and the number of handover number N corresponding to medium speed is replaced from L2m to L3m.

 Then, the speed determination unit 15 starts from 0 m based on the distance between the position of the mobile terminal 10 detected first and the position of the mobile terminal 10 detected last in the speed determination period T3. If L1m or less, it is determined that the speed is low, if L1m to L2m or less, it is determined to be medium speed, and if L2m to L3m or more, it is determined to be high speed.

 Here, the above-described L1, L2, and L3 are set so that the distance of L2 is longer than L1, and is set so that the distance of L3 is longer than L2.

 The period changing unit 16 includes a reception quality calculation period-speed determination period-speed correspondence table as illustrated in the example of FIG. 4, and based on the speed determined by the speed determination unit 15, the reception quality calculation period-speed With reference to the determination period-speed correspondence table, the reception quality calculation period T2 of the reception quality measuring unit 11 and the speed determination period T3 of the speed determination unit 15 are changed.

 Specifically, the period changing unit 16 refers to the reception quality calculation period-speed determination period-speed correspondence table when the speed determination unit 15 determines that the moving speed of the mobile terminal 10 is high, for example. The reception quality calculation period T2 is changed to 10 sec, and the speed determination period T3 is changed to 60 sec.

 The period changing unit 16 includes a reception quality measurement cycle-reception quality calculation period-speed determination period-speed correspondence table as shown in the example of FIG. 5, and based on the moving speed determined by the speed determination unit 15. The reception quality measurement period T1 and reception quality calculation period T2 of the reception quality measurement unit 11 and the speed determination period T3 of the speed determination unit 15 may be changed.

 In such a case, if the moving speed of the mobile terminal 10 is determined to be, for example, high speed by the speed determining unit 15, the period changing unit 16 described above is the reception quality measurement period−reception quality calculation period−speed determination period−speed correspondence table. , The reception quality measurement period T1 is changed to 1 sec, the reception quality calculation period T2 is changed to 10 sec, and the speed determination period T3 is changed to 60 sec.

 Further, the period changing unit 16 includes a reception quality calculation period-handover count-speed correspondence table as shown in the example of FIG. 6, and based on the moving speed determined by the speed determining unit 15, the reception quality described above is provided. The calculation period T2 and the number of handovers N in the number of handovers-speed table may be changed.

 In this case, the period changing unit 16 calculates the reception quality by referring to the reception quality calculation period-handover count-speed correspondence table when the speed determination unit 15 determines that the moving speed of the mobile terminal 10 is high, for example. The period T2 is changed to 10 sec, the low speed value of the handover frequency N in the handover frequency-speed table is changed from 0 times to 9 times, the medium speed value is changed from 10 times to 15 times, and the high speed value is changed. Is changed to 16 times or more.

(Operation of portable terminal according to this embodiment)
The operation of the mobile terminal 10 having the above configuration will be described with reference to the drawings. 7 to 8 are flowcharts illustrating the operation of the mobile terminal 10 according to the present embodiment.

 As shown in FIG. 7, in step S <b> 101, the handover number detection unit 13 detects the number of handovers (for example, 6) of the mobile terminal 10.

 In step S102, the speed determination unit 15 performs the handover number-speed illustrated in FIG. 3 based on the number of handovers (for example, 6) detected by the handover number detection unit 13 within the period of the speed determination period T3. The moving speed (for example, high speed) of the mobile terminal 10 is determined with reference to the correspondence table.

 In step S103, the period changing unit 16 refers to the reception quality calculation period-speed determination period-speed correspondence table shown in FIG. 4 based on the speed determined by the speed determination unit 15 (for example, high speed). The reception quality calculation period T2 for calculating the second reception quality of the measurement unit 11 is changed (for example, 10 seconds), and the speed determination period T3 for determining the speed of the speed determination unit 15 is changed (for example, 60 seconds).

 Next, in step S201, the reception quality measurement unit 11 measures the first reception quality for each cell of the signal received from the cell in which the mobile terminal 10 is present at the reception quality measurement period T1.

 In step S202, the reception quality measuring unit 11 calculates the second reception quality for each cell by a predetermined calculation method based on the first reception quality measured within the reception quality calculation period T2.

 In step S203, the cell selection unit 12 selects the cell with the second best reception quality based on the calculated second reception quality for each cell.

 In step S204, the mobile terminal 10 notifies the base station managing the serving cell of the identification information of the second cell with good reception quality selected in step S203.

 When the mobile terminal 10 is notified from the base station to change the serving cell to the cell with the second best reception quality selected in step S203, the portable terminal 10 designates the serving cell as the second serving cell. The handover process for changing to the cell having the best reception quality is performed.

(Operations and effects of the mobile terminal according to the present embodiment)
According to the mobile terminal according to the present embodiment, the reception quality calculation period T2 and the speed determination period T3 can be changed according to the moving speed of the mobile terminal being moved. The cell selection process for selecting the best cell can be performed appropriately, and the serving cell is changed to the cell with the best reception quality selected by the cell selection process based on the notification from the base station. Handover processing can be performed.

It is a block diagram which shows the structure of the portable terminal which concerns on this embodiment. It is a figure which shows the relationship of the reception quality measurement period T1, the reception quality calculation period T2, and the speed determination period T3 of the portable terminal which concerns on this embodiment. FIG. 6 is a diagram illustrating a handover speed correspondence table of the mobile terminal according to the present embodiment. It is a figure which shows the reception quality calculation period T2-speed determination period T3-speed correspondence table of the portable terminal which concerns on this embodiment. FIG. 10 is a diagram illustrating a reception quality measurement period T1−reception quality calculation period T2−speed determination period T3−speed correspondence table of the mobile terminal according to the present embodiment. FIG. 10 is a diagram illustrating a reception quality calculation period T2-handover count N-speed correspondence table of the mobile terminal according to the present embodiment. It is a figure which shows the flowchart regarding the moving speed and period change of the portable terminal of the portable terminal which concerns on this embodiment. FIG. 6 is a flowchart illustrating measurement and calculation of reception quality of a signal received by a mobile terminal according to the present embodiment and cell selection. It is a figure which shows the relationship between the reception quality measurement period T1 and the reception quality calculation period T2 of the portable terminal which concerns on a prior art. FIG. 6 is a conceptual diagram illustrating a mobile terminal that moves according to the prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Portable terminal 11 ... Reception quality measurement part 12 ... Cell selection part 13 ... Handover frequency detection part 14 ... Speed determination part 15 ... Position detection part 16 ... Period change part T1 ... Reception quality measurement period T2 ... Reception quality calculation period T2a: Reception quality calculation period T3: Speed determination period

Claims (6)

A mobile terminal that communicates with a network via a base station that manages a serving cell,
Reception in which a first reception quality of a received signal is measured at a predetermined period, and a second reception quality of the received signal is calculated based on the first reception quality measured within a first period. A quality calculator,
Based on the second reception quality calculated by the reception quality calculation unit, a cell selection unit that selects a cell in which the signal having the second good reception quality is transmitted;
A speed determining unit for determining a moving speed of the mobile terminal;
A portable terminal comprising: a period changing unit that changes the length of the first period based on the moving speed determined by the speed determining unit. Further comprising a cell change count detection unit for detecting the number of changes of the serving cell,
The said speed determination part determines the said moving speed based on the frequency | count of change of the said serving cell detected by the said cell change frequency detection part in the said 2nd period. Mobile terminal. Further comprising a position detector for detecting position information of the mobile terminal;
The mobile device according to claim 1, wherein the speed determination unit determines a moving speed of the mobile terminal based on the position information detected by the position detection unit within the second period. Terminal machine.   The mobile terminal according to any one of claims 1 to 3, wherein the period changing unit changes the length of the second period based on the moving speed determined by the speed determining unit. .   4. The mobile phone according to claim 1, wherein the period changing unit changes a period for measuring the first reception quality based on the moving speed determined by the speed determining unit. 5. Terminal machine. A communication method in which a mobile terminal communicates with a network via a base station that manages a serving cell,
Step A for determining the moving speed of the mobile terminal;
Step B for determining the first period based on the determined moving speed;
Measuring a first reception quality of the received signal at a predetermined period; and
Calculating a second reception quality of the received signal based on the first reception quality measured in the first period; and
Based on the second reception quality calculated in step D, selecting a cell in which the signal having a good second reception quality is transmitted;
Notifying the base station of the cell selected in step E;
A communication method comprising: a step G of changing the serving cell to the cell selected in step E based on a notification from the base station.

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