JP2009027459A - Mobile communication terminal, and method for cell reselection of mobile communication terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile communication terminal which can suppress unnecessary cell reselection operation. <P>SOLUTION: The mobile communication terminal 10 of the invention is provided with: a reselection operation control unit 12 which carries out cell reselection when an execution standard of cell reselection is satisfied; and a discrimination unit 14 which discriminates that cell reselection is repeatedly executed not only between special cells but also between different calling areas. The cell reselection control unit 12 changes the execution standard to an execution standard A when the discrimination unit 14 discriminates that cell reselection is being repeatedly executed between the special cells, and moreover changes the execution standard to an execution standard B when the discrimination unit 14 discriminates that cell reselection is being repeatedly executed between the calling areas. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a mobile communication terminal and a cell reselection method for the mobile communication terminal.

  2. Description of the Related Art Conventionally, mobile communication terminals such as mobile phones select a cell with high communication quality from a plurality of cells formed so that a part of them overlap, and transmit and receive radio signals to and from the selected cell. To communicate. For example, with respect to two types of adjacent cells A and B, the mobile communication terminal is in the area of cell A, and the mobile communication terminal measures (monitors) the communication quality of cell B adjacent to cell A. Take up the state. In this state, the cell A is called an active cell or a serving cell, and the cell B is called a monitor cell or an adjacent cell. The reception quality of the active cell A and the monitor cell B is measured based on the electric field strength (CPICH-RSCP) of the common pilot channel of the active cell A and the monitor cell B, the reception quality (CPICH-Ec / N0) of the common pilot channel, etc. Is done. Then, when the reception quality of the monitor cell B becomes better than that of the active cell A, the active cell is changed from the cell A to the cell B. This series of operations is called celery selection operation.

  FIG. 6 shows an example of a graph of radio wave reception quality according to time in two cells (cell A and cell B) measured by the mobile communication terminal. As shown in FIG. 6, the cell reselection operation occurs at the timing (time indicated by reference numeral 61 in FIG. 6) at which the cell with the best reception quality is switched. Note that how much the communication quality of the monitor cell becomes better than that of the active cell is determined depending on the cell reselection parameters (Q-hyst, T-reselection, etc.) included in the cell broadcast information. ) Value. “Broadcast information” is information that is constantly transmitted from the network in order to notify various parameters to the mobile communication terminal. For example, when the state of “cell B reception quality−cell A reception quality ≧ Q-hyst” continues for the time set in T-reselection, the cell reselection operation is performed. Details regarding various parameters of the celery selection operation are described in Non-Patent Document 1.

  The cell reselection operation varies depending on the communication status.

  In the case of the IDLE state and the Cell-PCH state (the description of the RRC state is described in Non-Patent Document 2), the broadcast information of the cell B to be shifted when moving from the active cell A to the monitor cell B If it is determined that the cell B is not in a restricted state and it can be determined that the cell B is allowed to be in the service area, the cell B moves to the cell B and is in the service area. If it is found that the calling area has been crossed based on the broadcast information, a location registration request (Routing Area Update procedure or Location Update procedure; details are described in Non-Patent Document 3) is performed in the migration destination cell. To the side that their calling area has changed.

  In the case of the Cell-FACH state, when transitioning from the active cell A to the monitor cell B, after acquiring broadcast information of the cell B to be migrated, the CellUpdate procedure is performed and the reselection is reported to the network side. If it is found that the call area is straddled, a location registration request is made in the migration destination cell B, and the network side is notified that the call area has been changed.

  By the way, in the vicinity of the cell boundary, for example, the electric field strength (CPICH-RSCP), reception quality (CPICH-Ec / N0), etc. received by the mobile communication terminal fluctuate periodically or in bursts due to fading or the like. As a result, a state in which the reselection operation is excessively repeated between a plurality of cells having substantially no difference in reception quality, that is, so-called flickering may occur. When the fluttering occurs, there may be a disadvantageous situation such as a significant increase in power consumption compared to the case of the original stationary state.

In view of such circumstances, Japanese Patent Application Laid-Open No. H10-228707 describes a technique for suppressing an unnecessary celery selection operation to suppress fluttering. In Patent Document 1, it is determined whether or not a flutter has occurred by counting the number of times a cell is set as a local station cell (active cell). When it is determined that the flicker has occurred, unnecessary cell reselection operation is suppressed by correcting the cell reselection condition to make it difficult to satisfy the condition.
JP 2006-157217 A 3GPP TS25.304 Chapter 5.2 3GPP TS 24.331 Chapter 6 FIG. 5 3GPP TS 24.008

  However, the conventional technology such as Patent Document 1 merely suppresses unnecessary cell reselection operation between adjacent cells, and specifies a reselection operation between cells straddling the calling areas, and performs special measures. There was a problem that could not be taken.

  The reselection operation between cells straddling call areas has a problem that the amount of power consumption is greatly increased because the operation amount is large compared to the case of repeating cell reselection in the same call area. Furthermore, while reporting to the network that the calling area has been moved, the network side processing is such that the mobile communication terminal location information is being exchanged between the nodes, and the mobile communication terminal is present at the destination. There is a problem in that the mobile communication terminal frequently falls into a state where it cannot be called because the information indicating that the mobile communication terminal is not reflected. Therefore, in the technology for suppressing fluttering, it is desirable that the operation can be suppressed against reselection across the calling area.

  Therefore, the present invention solves the above-described problems, suppresses unnecessary cell reselection operation more favorably than the prior art, and can particularly suppress unnecessary cell reselection operation across different calling areas. The purpose is to provide a migration method.

  In order to solve the above-described problem, the mobile communication terminal of the present invention satisfies an implementation criterion for determining whether or not to perform the cell reselection operation in the mobile communication terminal performing a cell reselection operation to reselect a serving cell. A first determination unit for determining that the cell reselection operation is repeatedly executed between specific cells, and a specific determination by the first determination unit. When it is determined that the cell reselection operation is repeatedly executed between cells, the first change unit that changes the execution standard to the first execution standard and the cell reselection operation across different call areas are repeated. A second determination unit that determines that the call is being executed, and a cellularity that straddles between different call areas by the second determination unit. And a second changing means for changing the implementation standard to a second implementation standard that is stricter than the first implementation standard when it is determined that the retraction operation is repeatedly performed. .

  In order to solve the above-mentioned problem, the cell reselection method of the present invention is a cell reselection method of a mobile communication terminal that performs a cell reselection operation for reselecting a serving cell. An implementation step of performing the reselection operation when an implementation criterion for determining whether or not a first determination step of determining that the cell reselection operation is repeatedly performed between specific cells; and In the first determination step, when it is determined that the cell reselection operation is repeatedly performed between specific cells, a different calling area is changed from the first change step for changing the execution standard to the first execution standard. A second determination step for determining that the celery selection operation is repeatedly executed; and the second determination step. A second change step for changing the implementation standard to a second implementation standard that is stricter than the first implementation standard, when it is determined that the cell reselection operation across different calling areas is repeatedly executed in It is characterized by including.

  By these configurations, when the celery selection operation is repeatedly executed between specific cells, the implementation standard for determining whether to perform the celery selection operation is changed to the first implementation standard. The celery selection operation is less likely to be performed. In addition, when the cell reselection operation across different calling areas is repeatedly executed, the cell reselection operation is more difficult to be performed than the first execution standard by changing the execution standard to the second execution standard. . Thereby, excessive generation | occurrence | production of the cell reselection operation | movement straddling between different calling areas can be suppressed suitably. As a result, it is possible to improve the incoming call success rate by reducing the state where the mobile communication terminal cannot be called. In addition, since the frequency with which the mobile communication terminal moves to the call area can be reduced, power consumption associated with unnecessary cell reselection operation can be suppressed.

  The mobile communication terminal of the present invention includes a stationary state detection unit that detects a state in which the mobile communication terminal is stationary, and a stationary state of the mobile communication terminal that is detected by the stationary state detection unit. It is preferable to further include third changing means for changing the execution standard to the third execution standard.

  Similarly, the cell reselection method of the present invention includes a stationary state detection step for detecting a state where the mobile communication terminal is stationary, and a case where the stationary state of the mobile communication terminal is detected in the stationary state detection step. It is preferable that the method further includes a third changing step of changing the execution standard to a third execution standard.

  With these configurations, when the mobile communication terminal is in a stationary state, the cell reselection operation is performed from the normal time by changing the execution standard for determining whether to perform the cell reselection operation to the third operation standard. It becomes difficult to be done. Thereby, since the stationary state of the mobile communication terminal that does not need to perform the cell reselection operation can be recognized and the occurrence of the cell reselection operation can be suppressed, unnecessary flutter can be avoided and power consumption can be suppressed.

  According to the mobile communication terminal and the cell transition method of the present invention, it is possible to suitably suppress an excessive occurrence of cell reselection operation across different call areas. As a result, it is possible to improve the incoming call success rate by reducing the state where the mobile communication terminal cannot be called. In addition, since the frequency with which the mobile communication terminal moves to the call area can be reduced, power consumption associated with unnecessary cell reselection operation can be suppressed.

  Hereinafter, preferred embodiments of a mobile communication terminal according to the present invention will be described with reference to the drawings. When possible, the same reference numerals are given to the same elements in the description of the drawings, and duplicate descriptions are omitted.

  First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a functional configuration of the mobile communication terminal according to the present embodiment.

  The mobile communication terminal 10 transmits and receives information to and from other terminals and servers using a mobile communication network. The mobile communication network is composed of a plurality of calling areas, and each of the calling areas is composed of a plurality of cells formed so that a part thereof overlaps. A base station is arranged in each cell, and the mobile communication terminal transmits and receives information via the base station of the active cell in which it is located. Further, the mobile communication terminal periodically receives broadcast information of the cell from the base station of the active cell and the monitor cell adjacent to the active cell. The broadcast information includes a cell ID that is information for specifying a cell, a call area number that is information for specifying a call area to which the cell belongs, position information, carrier code, common channel information, neighboring cell information, cell reselection parameters, and the like. Is done. In the present embodiment, the mobile communication terminal 10 receives a radio signal including broadcast information from the base station, and reselects an active cell as necessary based on the reception quality at this time.

  As shown in FIG. 1, the mobile communication terminal 10 functionally includes a radio quality measurement unit 11, a reselection operation control unit (control unit, first change unit, second change unit) 12, reselection operation. The storage unit 13, the determination unit (first determination unit, second determination unit) 14, and the implementation reference storage unit 15 are configured.

  The radio quality measurement unit 11 measures the reception quality of radio signals received from the base stations of the active cell and the monitor cell. The radio quality measurement unit 11 measures, for example, reception field strength (CPICH-RSCP) and reception quality (CPICH-Ec / N0) for each of the active cell and the monitor cell.

  The reselection operation control unit 12 performs the celery selection operation when an implementation criterion for determining whether to perform the celery selection operation is satisfied. The reselection operation control unit 12 determines whether or not to perform the cell reselection operation based on the reception quality of the active cell and the monitor cell measured by the radio quality measurement unit 11, and the reception quality of the active cell and the monitor cell is determined. The celery selection is performed when an execution standard for a predetermined celery selection operation is satisfied. The implementation criteria for the celery selection operation are selected from a plurality of preset criteria according to the history of past celery selection operations. In the present embodiment, three types are set in advance: normal standard, implementation standard A (first implementation standard), and implementation standard B (second implementation standard). The implementation criterion is selected according to the determination result of the determination unit 14 based on the history of past celery selection operations, for example. The selected implementation standard is stored in the implementation standard storage unit 15.

  Here, the implementation standards (normal standard, implementation standard A, implementation standard B) set in the present embodiment will be described. In the normal standard, the cell reselection operation is performed when the reception quality of the monitor cell is higher by Q-hyst (dB) than that of the active cell for T-reselection (seconds). In many cases, the reselection operation is performed when the reception quality is higher by about 2 (dB) than the active cell for 3 seconds. Q-hyst and T-reselection are celery selection parameters included in the broadcast information.

  On the other hand, the implementation standard A performs the cell reselection operation when the reception quality of the monitor cell is higher than the active cell by Q-hyst × 2 (dB) for T-reselection × 2 (seconds). . For example, the cell reselection is set when the monitor cell reception quality is 4 dB higher than the active cell for 6 seconds. In this setting example, the implementation standard A is the reception quality deviation between the active cell and the monitor cell required for the operation implementation, and the duration of the deviation is twice that of the normal standard. , It becomes difficult to perform the celery selection operation from the normal standard.

  The implementation standard A measures the reception quality or electric field strength of the active cell and the monitor cell for X seconds (several seconds to several tens of seconds), and the average value of the reception quality or electric field strength of the monitor cell is Q with respect to the active cell. When it is higher by -hyst (dB), the celery selection operation may be performed. In this case, for example, when the reception quality of the cell A that is the active cell and the cell B that is the monitor cell is measured for 10 seconds, and the average value of the measured reception quality is 2 (dB) or more, the cell B is higher. The cell reselection is performed on the cell B.

  On the other hand, in the implementation standard B, when the reception quality of the monitor cell is higher by Q-hyst × 2 (dB) than the active cell for T-reselection × 3 (seconds), or when the reception quality of the monitor cell is active When a state that is Q-hyst × 3 (dB) higher than the cell continues for T-reselection (seconds), the cell reselection operation is performed. For example, when the state in which the reception quality of the monitor cell is 4 (dB) higher than that of the active cell continues for 9 seconds, or when the state of 6 (dB) higher continues for 3 seconds, the cell reselection is performed. . In this setting example, at least one of the deviation of the reception quality between the active cell and the monitor cell required for performing the operation and the duration of the deviation is stricter than the case of the implementation standard A. Therefore, the celery selection operation is less likely to be performed than the implementation standard A.

  The implementation standard B measures the reception quality or electric field strength of the active cell and the monitor cell for X × 2 seconds, and the average value of the reception quality or electric field strength of the monitor cell is Q-hyst (dB) minutes relative to the active cell. When it was high or the reception quality or electric field strength of the active cell and the monitor cell was measured for X seconds, the average value of the reception quality or electric field strength of the monitor cell was higher by Q-hyst × 2 (dB) than the active cell In some cases, a celery selection operation may be performed. In this case, for example, the reception quality of cell A, which is an active cell for 20 seconds, and cell B, which is a monitor cell, is measured, and the average value of cell B is higher than 2 (dB) or higher for 10 seconds. The reception quality of a certain cell A and a monitoring cell B is measured, and when the average value of the cell B is higher than 4 (dB), the cell reselection is performed on the cell B. .

  The reselection operation storage unit 13 stores information when the cell reselection operation is performed for all of the past or within a predetermined time. For each past cell reselection operation, the reselection operation storage unit 13 includes, for example, the cell ID of the active cell before and after the cell reselection operation, the execution time of the cell reselection operation, the calling area number of the active cell before and after the cell reselection operation, etc. Is remembered. These pieces of information are extracted from the broadcast information of the active cell before and after the cell reselection operation.

  The determination unit 14 determines that the celery selection operation is repeatedly executed between specific cells (hereinafter referred to as “flapping”). The determination unit 14 is configured to perform a predetermined number of cell reselection operations between a plurality of specific cells within a certain time period, or a specific number of cell reselection operations between a plurality of specific cells among a certain number of cell reselection operations. When it is implemented, it is determined that a flutter has occurred. For example, the determination unit 14 repeats the reselection between the cell A and the cell B three times or more in 2 minutes, or the reselection between the cell A and the cell B is performed three times out of the three reselections. If it is, the flutter judgment is performed. Specifically, the determination unit 14 refers to the reselection operation storage unit 13 and acquires the cell ID information of the active cell before and after the operation for each of the past cell reselection operations. Make a decision.

  Furthermore, the determination unit 14 determines that a celery selection operation across different calling areas is repeatedly executed (hereinafter referred to as “inter-area flicker”). The determination unit 14 determines that an inter-area flutter has occurred when a cell reselection operation involving a change of the calling area is performed a predetermined number of times within a certain period of time. For example, the determination unit 14 performs inter-area flutter determination when celery selection across the calling area is performed twice or more in 2 minutes. Specifically, the determination unit 14 refers to the reselection operation storage unit 13, acquires information on the call area numbers of active cells before and after the operation for each past cell reselection operation, and based on this information Inter-area flutter judgment is performed.

  In addition, when the current implementation standard is the implementation standard A or B, the determination unit 14 determines whether to shift the implementation standard to the normal standard. For example, when a state in which a flicker or the like occurs between cells after a state in which a flutter or the like occurs between arbitrary cells is considered, in most cases, the mobile communication terminal 10 is between these states. There may be a state in which no flutter or the like occurs in the moving state. Therefore, when the current implementation standard is the implementation standard A or B, it is desirable to return the implementation standard to the normal standard and make it an appropriate implementation standard according to the state of the aircraft.

  Examples of the transition condition to the normal reference include a case where a transition to a cell that has not been designated as an active cell has occurred in the history of cell reselection operations for a predetermined number of times or a predetermined time in the past. Alternatively, the above condition is that the reception level (CPICH-RSCP) or the reception quality (CPICH-Ec / N0) of the destination cell exceeds a predetermined amount or exceeds a predetermined amount for a predetermined time compared to the source cell. It may be continued. For example, when a reselection operation is performed on a cell that has not been involved in the cell reselection operation that has occurred in the past 5 minutes or in the past four times, the mobile communication terminal 10 has moved and a new active It is determined that the cell has been found, and it is determined that the execution standard of the cell reselection operation is shifted to the normal standard.

  Here, the reselection operation control unit 13 changes the implementation criteria as necessary based on the determination result of the determination unit 14. Specifically, when the current implementation standard is the normal standard, the reselection operation control unit 13 changes the implementation standard to the implementation standard A that is stricter than the normal standard when a flutter occurs. Change the implementation standard to implementation standard B, which is stricter than A. On the other hand, when the current implementation standard is the implementation standard A or B, the reselection operation control unit 13 changes the implementation standard to the normal standard when a condition for shifting to a predetermined normal standard is satisfied.

  The execution reference storage unit 15 stores the execution reference of the cell reselection operation selected by the reselection operation control unit 12 according to the determination result of the determination unit 14.

  FIG. 2 shows a hardware configuration of the mobile communication terminal 10. As shown in FIG. 2, the mobile communication terminal 10 includes hardware such as a CPU 101, a RAM 102, a ROM 103, an operation unit 104, a wireless communication unit 105, a display 106, and an antenna 107. Each function described in FIG. 1 has an operation unit 104, a wireless communication unit 105, and a display 106 under the control of the CPU 101 by loading predetermined computer software on hardware such as the CPU 101 and the RAM 102 shown in FIG. This is realized by reading and writing data in the RAM 102 and ROM 103.

  Next, the cell reselection process in the mobile communication terminal 10 of the present embodiment will be described using the flowchart of FIG. This process is repeatedly executed while the mobile communication terminal 10 is powered on.

  First, the reselection operation control unit 12 performs the celery selection parameters (Q-hyst, T-reselection) included in the broadcast information and the type of celery selection operation execution standard stored in the execution reference storage unit 15 (normal reference). Based on the implementation criteria A and the implementation criteria B), the implementation criteria for the celery selection operation are set (S101). Specifically, for example, the implementation standard is set by substituting the numeric data of the celery selection parameter included in the broadcast information into the parameter of the current implementation standard.

  Subsequently, the radio quality measurement unit 11 measures the radio quality of the active cell and the monitor cell (S102), and reports the measurement result to the reselection operation control unit 12. The reselection operation control unit 12 collates the measurement result from the radio quality measurement unit 11 with the execution standard of the cell reselection operation, and determines whether or not the execution standard of the cell reselection operation is satisfied (S103). When the implementation criteria for the celery selection operation are satisfied (for example, when the reception quality (CPICH-Ec / N0) of the monitor cell B is 2 dB better than the active cell A continues for 3 seconds), the step The process proceeds to S104. If the execution standard is not satisfied, the process is terminated without performing the celery selection operation.

  If it is determined in step S103 that the celery selection operation is to be performed, the reselection operation control unit 12 performs the celery selection operation (implementation step: S104). At this time, the reselection operation control unit 12 notifies the reselection operation storage unit 13 of information related to the performed cell reselection operation (cell ID and call area number of the active cell before and after the operation) and stores it together with the time. .

  Subsequently, the determination unit 14 determines whether the current celery selection execution standard is set to a normal standard (a setting standard using a conventional technique set before the installation of this function), or an implementation standard A or B. It is checked whether it is set to (new standard for reselection suppression) (S105). When the current implementation standard is the normal standard, the process proceeds to step S106. When the current implementation standard is the implementation standard A or B, the process proceeds to step S110.

  When the current implementation standard is the normal standard in step S105, the determination unit 14 continues to determine whether the cell reselection operation is repeatedly performed between specific cells (flapping determination) (first determination step: S106). If it is determined that the flutter has occurred, the process proceeds to step S107. If it is determined that no flutter has occurred, the process ends with the normal standard being the current implementation standard.

  If it is determined in step S106 that a flutter has occurred, the determination unit 14 continues to determine whether or not a cell reselection operation across different calling areas is repeatedly performed (inter-area flutter determination) (second Determination step: S107). When it is determined that there is no inter-area flutter, the determination unit 14 notifies the determination result to the reselection operation control unit 12, and the reselection operation control unit 12 changes the execution standard from the normal standard to the execution standard A. (First change step: S108). When it is determined that the inter-area flapping has occurred, the determination unit 14 notifies the determination result to the reselection operation control unit 12, and the reselection operation control unit 12 changes the execution standard from the normal standard to the execution standard B. (Second change step: S109).

  When the current implementation standard is the implementation standard A or B in step S105, the determination unit 14 determines whether or not to shift the implementation standard to the normal standard (S110). When it is determined that the implementation standard is shifted to the normal standard, the implementation standard is changed to the normal standard (S111). If it is determined that the implementation standard does not shift to the normal standard, the process ends with the implementation standard A or B being the current implementation standard.

  In steps S108, S109, and S111, when the implementation standard is changed to the normal standard, the implementation standard A, or the implementation standard B, respectively, the latest implementation standard stored in the implementation standard storage unit 15 is updated (S112). The implementation standard stored in the implementation standard storage unit 15 is used for the process of step S101 when the mobile communication terminal 10 next executes the process of this flowchart.

  In the cell reselection process shown in FIG. 3, when the current implementation standard is the normal standard, the mobile communication terminal 10 changes the implementation standard to the implementation standard A, which is stricter than the normal standard, and the inter-area fluctuation occurs. Sometimes, the implementation standard is changed to an implementation standard B that is stricter than the implementation standard A. On the other hand, when the current implementation standard is the implementation standard A or B, the mobile communication terminal 10 changes the implementation standard to the normal standard when a condition for transition to a predetermined normal standard is satisfied. This is because when there is no fluttering, it is desirable to relax the implementation standard so that it can be easily transferred to an appropriate cell.

  As described above, according to the mobile communication terminal 10 in the first embodiment, when the determination unit 14 determines that the cell reselection operation is repeatedly executed between specific cells (flapping), the reselection operation control unit. 12 changes the implementation standard from the normal standard to the implementation standard A, so that the celery selection operation is less likely to be performed than in the normal standard. Further, when the determination unit 14 determines that the cell reselection operation across different calling areas is repeatedly performed (inter-area flapping), the reselection operation control unit 12 changes the execution standard from the normal standard to the execution standard B. As a result, the celery selection operation is more difficult to be performed than in the implementation standard A. Thereby, especially the excessive generation | occurrence | production of the flutter between areas can be suppressed suitably. As a result, it is possible to reduce the state where the mobile communication terminal 10 cannot be called and to improve the incoming call success rate. In addition, since the frequency with which the mobile communication terminal 10 reports to the network that the mobile communication terminal 10 has moved in the calling area can be reduced, it is possible to suppress power consumption associated with unnecessary cell reselection operation.

  Next, a second embodiment of the present invention will be described with reference to FIG. 4 and FIG. FIG. 4 shows a functional configuration of the mobile communication terminal 20 in the second embodiment. Since the configuration of the mobile communication terminal 20 is similar to the configuration of the mobile communication terminal 10 described in detail in the first embodiment, common constituent elements are denoted by the same-symbols (same numbers at the end). While omitting the description, the differences from the first embodiment will be described in detail.

  The mobile communication terminal 20 includes a sensor unit 26 in addition to a radio quality measurement unit 21, a reselection operation control unit (third changing unit) 22, a reselection operation storage unit 23, a determination unit 24, and an implementation reference storage unit 25. And a stationary state detector (stationary state detector) 27.

  The sensor unit 26 includes, for example, a plurality of sensors such as a GPS sensor, an acceleration sensor, a vibration sensor, a speed sensor, or an image sensor, and periodically transmits information acquired by using the function of each sensor to the stationary state detection unit 27. To do. The GPS sensor acquires GPS data such as latitude and longitude. The acceleration sensor acquires the acceleration of the mobile terminal. The vibration sensor acquires vibration information of the mobile terminal. The speed sensor acquires the moving speed of the mobile terminal. The image sensor acquires the position variation amount of the mobile terminal from the camera image.

  The stationary state detection unit 27 determines whether the mobile communication terminal 20 is in a completely stationary state or a substantially stationary state (stationary state) based on information periodically received from the sensor unit 26. As a determination criterion for the stationary state, for example, whether the latitude / longitude measured by the GPS sensor is the same before and after the celery selection, or whether the acceleration detected by the acceleration sensor is 0, etc. Can be mentioned.

  The reselection operation control unit 22 can further set an execution standard C as an execution standard for the cell reselection operation in addition to the normal standard, the execution standard A, and the execution standard B of the first embodiment. The celery selection operation basically assumes the case where the mobile communication terminal is moving, and when it is in a moving state, it is an operation that always allows a high-quality cell to be located. In a stationary state, the mobile communication terminal may generate an unnecessary celery selection operation and cause flickering or the like. Therefore, in the present embodiment, when the stationary state is detected, the execution criteria for the celery selection operation are changed.

  Specifically, the reselection operation control unit 22 changes the implementation standard to the implementation standard C (third implementation standard) when the stationary state detection unit 27 determines that the vehicle is stationary. In addition, when it is determined that the state is still and it is determined that a flutter has occurred, the implementation standard is changed to the implementation standard A (first and third implementation standards). When it is determined that the state is still and it is determined that the inter-area flapping has occurred, the implementation standard is changed to the implementation standard B (second and third implementation standards).

  In the implementation standard C, a state in which the reception quality of the monitor cell is higher by Q-hyst (dB) than that of the active cell continues for T-reselection (seconds) as in the normal standard, and the stationary state detection unit 27 performs mobile communication. When it is determined that the terminal 20 is not stationary, a celery selection operation is performed. The implementation standard C may be the same as the implementation standard A described above. Since the operation standard C is stricter because the operation is performed than the normal standard, the celery selection operation is less likely to be performed than the normal standard.

  Next, the cell reselection process in the mobile communication terminal 20 of the present embodiment will be described using the flowchart of FIG. Note that this operation is basically the same as the operation of the mobile communication terminal 10 described in detail in the first embodiment (see FIG. 3). Specifically, steps S201 to S205, S207, and S209 to S214 shown in FIG. 5 correspond to steps S101 to S112 shown in FIG. Hereinafter, processing S206 to S208 unique to the present embodiment will be described.

  In step S206, the stationary state detection unit 27 determines whether or not the mobile communication terminal 20 is stationary based on various information acquired by the sensor unit 26 (stationary state detection step). If it is determined that the mobile terminal 20 is not stationary, it is determined that the mobile communication terminal 20 is moving, and the process ends with the current normal reference. If it is determined that the camera is stationary, the process proceeds to step S207.

  In step S207, the determination unit 24 determines whether or not a flutter has occurred. This determination is the same as step S106 (see FIG. 3) of the first embodiment. If it is determined that the flutter has occurred, the process proceeds to step S209. If it is determined that no fluttering has occurred, the process proceeds to step S208, and the reselection operation control unit 22 changes the execution reference from the normal reference to the execution reference C (third change step).

  When the current implementation standard is any of the implementation standards A to C in step S205, the stationary state detection unit 27 or the determination unit 24 determines whether or not to shift the implementation standard to the normal standard (S110). The transition condition from the implementation standard C to the normal standard is that the stationary state detection unit 27 determines that the stationary state is not stationary (for example, when the latitude / longitude before reselection and after reselection differ depending on the output of the GPS sensor, the speed And when the transition condition from the implementation standard A to the normal standard is satisfied as described in step S110 of FIG. 3.

  In the cell reselection process shown in FIG. 5, when the current implementation standard is the normal standard, the mobile communication terminal 20 changes the implementation standard to the implementation standard A, which is stricter than the normal standard, and the inter-area fluctuation occurs. Sometimes, the implementation standard is changed to an implementation standard B that is stricter than the implementation standard A. In a stationary state, the standard is changed to an implementation standard C obtained by adding a stationary determination (SS06) to the normal standard. The implementation standard C may be the same as the implementation standard A. On the other hand, when the current implementation standard is any one of the implementation standards A to C, the mobile communication terminal 20 changes the implementation standard to the normal standard when a condition for shifting to a predetermined normal standard is satisfied. This is because when there is no fluttering, it is desirable to relax the implementation standard so that it can be easily transferred to an appropriate cell.

  In the cell reselection process shown in FIG. 5, when it is determined that the mobile communication terminal 20 is in a stationary state (S206), the implementation standard is changed to the implementation standard C. Alternatively, it is determined that the mobile communication terminal 20 is in a stationary state. If it is determined (S206) and flickering has occurred (S207), the implementation standard may be changed to the implementation standard C.

  As described above, according to the mobile communication terminal 20 in the second embodiment, when the stationary state detection unit 27 detects the stationary state of the mobile communication terminal 20, the execution reference for the celery selection operation is changed to the execution reference C. As a result, the celery selection operation is less likely to be performed than in the case of the normal reference. Thereby, since the stationary state of the mobile communication terminal that does not need to perform the cell reselection operation can be recognized and the occurrence of the cell reselection operation can be suppressed, unnecessary flutter can be avoided and power consumption can be suppressed.

It is a block diagram which shows the functional structure of the mobile communication terminal which concerns on the 1st Embodiment of this invention. It is a figure which shows the hardware constitutions of a mobile communication terminal. It is a flowchart which shows the cell reselection process in the mobile communication terminal of 1st Embodiment. It is a block diagram which shows the functional structure of the mobile communication terminal in 2nd Embodiment. It is a flowchart which shows the cell reselection process in the mobile communication terminal of 2nd Embodiment. It is a figure which shows the example of the graph of the reception quality of the electromagnetic wave according to the time in two cells measured by a mobile communication terminal.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10, 20 ... Mobile communication terminal 11, 21 ... Radio quality measurement part, 12, 22 ... Reselection operation control part, 13, 23 ... Reselection operation storage part, 14, 24 ... Determination part, 15, 25 ... Implementation standard Storage unit, 26 ... sensor unit, 27 ... stationary state detection unit.

Claims (4)

In a mobile communication terminal performing cell reselection operation to reselect a serving cell,
Control means for performing the celery selection operation when an implementation criterion for determining whether to perform the celery selection operation is satisfied;
First determination means for determining that a cell reselection operation is repeatedly performed between specific cells;
A first changing means for changing the execution reference to the first execution reference when the first determination means determines that the cell reselection operation is repeatedly executed between specific cells;
A second determination means for determining that a cell reselection operation across different call areas is repeatedly executed;
When it is determined by the second determination means that the cell reselection operation across different calling areas is repeatedly executed, the execution standard is changed to a second execution standard that is stricter than the first execution standard. 2 change means;
A mobile communication terminal comprising: A stationary state detecting means for detecting a state in which the mobile communication terminal is stationary;
A third changing unit that changes the execution standard to a third implementation standard when the stationary state of the mobile communication terminal is detected by the stationary state detection unit;
The mobile communication terminal according to claim 1, further comprising: In the cell reselection method of a mobile communication terminal that performs cell reselection operation to reselect a serving cell,
An implementation step of performing the celery selection operation when an implementation criterion for determining whether to perform the celery selection operation is satisfied;
A first determination step of determining that a cell reselection operation is repeatedly performed between specific cells;
A first changing step of changing the implementation standard to the first implementation standard when it is determined that the cell reselection operation is repeatedly performed between specific cells in the first determination step;
A second determination step for determining that a cell reselection operation across different call areas is repeatedly executed;
When it is determined in the second determination step that the cell reselection operation across different calling areas is repeatedly executed, the second execution standard is changed to a second execution standard that is stricter than the first execution standard. Change steps,
A cell reselection method for a mobile communication terminal including: A stationary state detecting step for detecting a state in which the mobile communication terminal is stationary;
A third changing step for changing the implementation standard to a third implementation standard when the stationary state of the mobile communication terminal is detected in the stationary state detection step;
The cell reselection method of the mobile communication terminal according to claim 3, further comprising:

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