JP2013201615A - Radio communication terminal, and method and program for controlling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress frequent occurrence of handover in a radio communication terminal that conforms to a plurality of communication methods.SOLUTION: A radio communication terminal 100 in a mobile communication system 1 includes a cell detection unit 17 for detecting a cell to be handed over, and stores history information 14, that represents the detected cell history, into a storage unit 13. When the cell is detected, an HO decision unit 18 in the radio communication terminal 100 decides whether handover is to be made to the cell, on the basis of the history represented by the history information 14. If the radio communication terminal 100 is in a loop state that frequently repeats movement between cells, the radio communication terminal 100 retains the cells in a loop list 15. When the HO decision unit 18 decides not to be handed over, an HO control unit 19 suppress the handover to the detected cell.

Description

  The present invention relates to a radio communication terminal in a mobile communication system, and more particularly to control of handover by a radio communication terminal.

  In mobile communication systems, handover techniques are used so that calls and data communications are not interrupted even when a wireless communication terminal moves. With the handover technique, the radio communication terminal can successively switch the communication destination radio base station to one having better communication quality.

  Such handover control may be performed in order to keep communication quality constant. For example, the number of wireless communication terminals accommodated in the communication area (cell) of the wireless base station is limited mainly by the wireless base station. Thereby, the communication quality in the cell is kept constant.

  Japanese Patent Laid-Open No. 2002-190769 (Patent Document 1 below) discloses a technique in which a wireless communication terminal controls execution of a handover. Patent Document 1 discloses a technique for selecting a communication method corresponding to a moving speed of a wireless communication terminal in a wireless communication terminal that supports a plurality of communication methods such as a PHS (Personal Handyphone System) method and a PDC (Personal Digital Cellular) method. It is disclosed. In Patent Document 1, when the moving speed of a wireless communication terminal is high, the wireless communication terminal selects a PDC system with a wide cell in order to avoid delay due to frequent handovers. On the other hand, when the moving speed is low, handover is unlikely to occur, so the PHS method with a high data communication speed is selected. As a result, in the invention of Patent Document 1, it is difficult to interrupt communication by avoiding frequent handovers.

JP 2002-190769 A

  The handover is started based on a change in the reception level of radio waves from the radio base station in the radio communication terminal. For this reason, when the wireless communication terminal is located near the boundary of the cell, handover between adjacent cells is likely to occur due to the building or the surrounding environment. When the wireless communication terminal frequently executes handovers, the data communication speed is temporarily reduced, and data discontinuities such as voice interruption in streaming data are likely to occur.

  Further, as the radio communication terminal frequently performs handover, there is a possibility that communication between the radio communication terminal and the radio base station occurs frequently, and the battery of the radio communication terminal is consumed quickly.

  Therefore, an object of the present invention is to suppress frequent occurrence of handover processing by a radio communication terminal and to suppress data delay and discontinuity associated with handover.

  The present invention is a radio communication terminal in a mobile communication system, and based on communication quality with a radio base station, a detection unit that detects a cell to be handed over, and an identifier of a cell detected by the detection unit A storage unit that stores history information indicating a history, and when the detection unit detects a cell, determines whether to perform a handover to the cell to be detected based on the identifier of the cell to be detected and the history indicated in the history information A determination unit; and a control unit that executes control to suppress handover to a cell related to detection when the determination unit determines that the handover should not be performed.

  Preferably, the control of the suppression of the handover by the control unit may be performed by stopping the communication process from the radio communication terminal to the radio base station, which is included in the communication procedure for executing the handover.

  Preferably, the handover is started by transmitting a predetermined report including the strength of the radio signal transmitted from the radio base station from the radio communication terminal to the radio base station. This may be done by stopping transmission of the report to the radio base station.

  Preferably, the control unit may cancel the control for suppressing the handover when the communication quality in the cell is below a predetermined threshold.

  Preferably, the determination unit may determine that the cell should not be handed over when the detected cell is included in the history indicated in the history information.

  Preferably, the determination unit should not be handed over to a predetermined cell group when the terminal is in a loop state that repeats movement of the predetermined cell group within a predetermined time based on the history indicated in the history information. When the detected cell is included in the history, the cell group in the loop state is determined to be formed by the cell and one or more cells detected after the time when the cell was detected in the past. Good.

  Preferably, the storage unit stores a loop list indicating cells for which execution of handover by the own terminal is inhibited, and the determination unit updates the loop list based on the history indicated in the history information, and the detected cell is When it is included in the loop list, it may be determined that the cell should not be handed over.

  Preferably, when the detected cell is included in the history indicated in the history information, the determination unit may register the cell and a cell detected after the time when the cell was detected in the past in the loop list. .

  Preferably, when the detection unit detects a cell that is not included in the loop list, the determination unit may delete the registered content of the loop list and determine that handover should be performed to a cell that is not included in the loop list. .

  Preferably, the determination unit may determine that a handover to the detected cell should be performed regardless of the registered content of the loop list when a predetermined time has elapsed since the loop list was updated.

  According to another embodiment, a method for controlling a wireless communication terminal in a mobile communication system is provided. The wireless communication terminal includes a wireless communication module, a memory, and a processor. In this method, a processor detects a cell to be handed over based on communication quality of wireless communication with a wireless base station by a wireless communication module, and the processor indicates a history of detected cell identifiers. A step of storing history information in a memory, and a step of determining whether or not to hand over to a cell to be detected based on an identifier of the cell to be detected and a history indicated in the history information when the processor detects the cell And a step of executing control for suppressing handover to a cell for detection when the processor determines that the handover should not be performed.

  According to another embodiment, a program for controlling a wireless communication terminal in a mobile communication system is provided. The wireless communication terminal includes a wireless communication module, a memory, and a processor. The program causes the processor to detect a cell to be handed over based on the communication quality of the wireless communication with the wireless base station by the wireless communication module, and history information indicating a history of the identifier of the detected cell, A step of storing in a memory; a step of determining whether or not to hand over to a cell to be detected based on an identifier of the cell to be detected and a history indicated in history information when the cell is detected; And a step of executing control to suppress handover to a cell related to detection when it is determined that it is not.

  ADVANTAGE OF THE INVENTION According to this invention, the frequent occurrence of the handover process by a radio | wireless communication terminal can be suppressed, and the data delay and discontinuity of data accompanying a handover can be suppressed.

1 is a diagram showing a partial configuration of a mobile communication system 1 including a radio communication terminal 100. FIG. 2 is a functional block diagram showing a configuration of a wireless communication terminal 100. FIG. It is a figure which shows the sequence of the handover in LTE. It is a figure which shows the history information 14 and the loop list 15. 5 is a flowchart showing the operation of the control unit 16 of the wireless communication terminal 100. 7 is a flowchart showing the operation of the HO determination unit 18. It is a figure which shows the process which the HO determination part 18 produces | generates the loop list | wrist 15 by judging whether the loop of a movement has generate | occur | produced. It is a figure which shows the loop between two cells. It is a figure which shows the loop between three cells.

<1 Overall configuration>
Hereinafter, a wireless communication terminal 100 according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of a part of a mobile communication system 1 including a radio communication terminal 100.

  As shown in FIG. 1, the mobile communication system 1 includes a radio communication terminal 100, a base station 200, a base station 300, and a base station 400. In the figure, wireless communication terminals other than the wireless communication terminal 100 and wireless base stations other than the base station 200 are not shown.

  Base station 200, base station 300, and base station 400 are radio base stations that support the LTE (Long Term Evolution) scheme.

  The wireless base station communicates wirelessly with wireless communication terminals in a certain range of surrounding area. The area of the certain range covered by the radio base station is called “cell”. The respective cells of the base stations 200, 300, and 400 are shown as a cell 201, a cell 301, and a cell 401 in FIG.

  The wireless communication terminal 100 communicates with a wireless base station corresponding to each cell while moving through each cell by executing handover.

  In the present embodiment, when the wireless communication terminal 100 exists in the vicinity of a cell boundary and a loop of movement between predetermined cells occurs, the wireless communication terminal 100 triggers a handover (HO: Hand Over) start. The handover execution is suppressed by not performing the process. This will be described in detail below.

<Configuration of 2 wireless communication terminal 100>
FIG. 2 is a functional block diagram showing the configuration of the wireless communication terminal 100. As shown in FIG.

<2.1 Overview of Wireless Communication Terminal 100>
As shown in FIG. 2, the radio communication terminal 100 includes a CDMA (Code Division Multiple Access) radio communication unit 21, a CDMA antenna 22, an LTE radio communication unit 31, an LTE antenna 32, a WiFi radio communication unit 41, A WiFi antenna 42, a baseband unit 10, a display unit 6, an audio output unit 7, an audio input unit 8, and an operation unit 9 are provided.

  The CDMA wireless communication unit 21 corresponds to a communication method using CDMA. The CDMA radio communication unit 21 includes an amplifier or the like, converts a signal from the baseband unit 10 into an antenna transmission frequency, and converts an antenna reception signal into a frequency that can be processed by the baseband unit 10.

  The CDMA wireless communication unit 21 receives, by the CDMA antenna 22, a wireless signal related to voice communication or data communication from another wireless communication terminal or a Web server connected to the Internet. The CDMA radio communication unit 21 performs signal processing on the received signal and outputs the signal to the baseband unit 10. Further, the CDMA radio communication unit 21 performs signal processing or the like on the transmission signal generated by the baseband unit 10, and transmits the processed transmission signal to another radio through the CDMA antenna 22 via the radio base station. Transmit to a communication terminal or a communication device connected to the Internet.

  The LTE wireless communication unit 31 corresponds to a communication method based on LTE. The LTE wireless communication unit 31 includes an amplifier or the like, converts a signal from the baseband unit 10 into an antenna transmission frequency, and converts an antenna reception signal into a frequency that can be processed by the baseband unit 10. That is, when the LTE radio communication unit 31 receives a radio signal related to data communication via the radio base station by the LTE antenna 32, the LTE radio communication unit 31 performs signal processing on the received signal and outputs the signal to the baseband unit 10. Further, the LTE wireless communication unit 31 performs signal processing or the like on the transmission signal generated by the baseband unit 10 and transmits the processed transmission signal through the LTE antenna 32.

  The WiFi wireless communication unit 41 corresponds to a communication method using WiFi, converts a signal from the baseband unit 10 into an antenna transmission frequency, and converts an antenna reception signal into a frequency that can be processed by the baseband unit 10. To do. The WiFi wireless communication unit 41 performs signal processing on the transmission signal generated by the baseband unit 10 and transmits the processed transmission signal through the WiFi antenna 42.

  The display unit 6 includes a display or the like, and displays various information such as characters, symbols, and figures by being controlled by a baseband unit 10 described later.

  The audio output unit 7 includes a speaker or the like, converts audio data from the baseband unit 10 into audio, and outputs the audio to the outside.

  The audio input unit 8 includes a microphone or the like, converts audio input from the outside into audio data, and outputs the audio data to the baseband unit 10.

  The operation unit 9 includes a keypad and the like, detects an operation from the user, and outputs it to the baseband unit 10.

  The baseband unit 10 includes a storage unit 13, a control unit 16, a CDMA processing unit 23, an LTE processing unit 33, and a WiFi processing unit 43. The baseband unit 10 includes a CPU (Central Processing Unit) (not shown). When the CPU reads out and executes the program stored in the storage unit 13, the baseband unit 10 performs the functions of the control unit 16 and the like, and manages the operation of the wireless communication terminal 100 in an integrated manner.

<2.2 Configuration of baseband unit 10>
The configuration of the wireless communication terminal 100 will be described in detail.

  The storage unit 13 includes a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and stores programs and data. The storage unit 13 stores history information 14 and a loop list 15 which will be described later.

  The CDMA processing unit 23 supports communication by the CDMA system, and performs modulation processing and demodulation processing on transmitted / received data.

  The LTE processing unit 33 supports communication using the LTE scheme, and performs modulation processing and demodulation processing on data to be transmitted and received.

  The WiFi processing unit 43 supports communication based on the IEEE 802.11 standard (IEEE 802.11n or the like), and performs modulation processing and demodulation processing on transmitted / received data.

  The control unit 16 controls data processing of the wireless communication terminal 100. Specifically, the control unit 16 includes a cell detection unit 17, a HO determination unit 18, and a HO control unit 19.

  The cell detection unit 17 detects a cell to be handed over based on the signal strength of a radio signal transmitted from the base station 200 or the like. In the present embodiment, the radio communication terminal 100 is described as performing handover control corresponding to the LTE scheme. In LTE, handover is started with the transmission of a measurement report as a trigger. The cell detection unit 17 determines whether or not the measurement report transmission condition is satisfied based on the measurement result of the signal strength of the radio signal transmitted from the base station 200 or the like. In the present embodiment, detection of a cell to be handed over by the cell detection unit 17 is performed as follows. That is, the cell detection unit 17 measures the signal strength of the radio signal from the base station as described above, sequentially determines whether or not the measurement report transmission condition is satisfied, and when there is a cell that satisfies the transmission condition, Suppose that a target cell is detected.

  The HO determination unit 18 determines whether a handover should be executed when a cell base unit 17 detects a radio base station to be handed over. Details will be described later.

  In the present embodiment, as described above, handover control corresponding to the LTE scheme is described as an example. Therefore, a handover method in LTE will be described.

FIG. 3 is a diagram illustrating a handover sequence in LTE.
In the figure, “UE” is a mobile station (UE: User Equipment), “Source eNB” is a handover source radio base station (eNB: eNodeB), “Target eNB” is a handover destination radio base station, “MME” "Is a mobility management entity, and" S-GW "is a serving gateway. In the figure, “HO” indicates handover.

  As shown in the figure, the handover is started when the UE measures the quality of the received signal, determines whether or not the condition for transmitting the Measurement Report is met, and transmits the Measurement Report to the Source eNB.

  There are various events that trigger the measurement report transmission by the UE. For example, the following EVENTs A1 to A5, B1 to B2, etc. Information such as a condition for searching for a radio base station and a frequency related to communication is notified from the radio base station to the UE. The UE measures neighboring base stations according to this information and transmits a measurement report to the radio base station. The radio base station instructs the UE to perform handover based on the Measurement Report notified in this way.

  In the following, “Serving Cell” is a cell to which the UE is connected. “IRAT” refers to inter-RAT (radio access technology) and indicates other networks. The inter-RAT handover is a handover to another network, for example, a handover from LTE to WCDMA (Wideband Code Division Multiple Access), LTE to EVDO (Evolution Data Only), or the like.

As values measured by the measurement, RSRP (Reference Signal Received Power) indicating the strength of the received signal and RSRQ (Reference Signal Received Quality) indicating the quality of the received signal are defined.
Event A1 (Serving Cell communication quality> threshold)
Event A2 (Serving Cell communication quality <threshold)
Event A3 (communication quality of neighboring cell <communication quality of serving cell as a result of offset addition)
Event A4 (Communication quality of neighboring cell> threshold)
Event A5 (Serving Cell communication quality <Threshold 1 and Adjacent Cell communication quality> Threshold 2)
Event B1 (adjacent IRAT Cell> threshold)
Event B2 (Serving Cell communication quality <Threshold 1 and neighboring IRAT Cell> Threshold 2)
<3 Data of wireless communication terminal 100>
Next, the history information 14 and the loop list 15 stored in the storage unit 13 will be described.

FIG. 4 is a diagram showing the history information 14 and the loop list 15.
<3.1 History information 14>
As shown in FIG. 4 (a), the history information 14 indicates that a cell detected by the cell detection unit 17 as a handover target by the wireless communication terminal 100 (for example, when a condition indicated in an event that triggers measurement report transmission is satisfied). The cell history of the adjacent base station of FIG. Every time a cell is detected by the cell detector 17, the history information 14 is updated. The cell detection history shown in the history information 14 includes a history number 141, a time 142, and a cell ID 143.

  The history number 141 is a number for distinguishing the history of the cells detected by the cell detection unit 17 and is given in the order of detection. In the figure, the identifiers of the detected cells with numbers “1” and “2” are stored in order from the number “0” of the history number 141 every time they are detected.

  Time 142 indicates the time when each cell is detected by the cell detection unit 17. In this figure, the time elapsed from the detection time of the cell indicated by the number “0” of the history number 141 to the subsequent cell detection by the cell detection unit 17 is stored in the time 142.

  The cell ID 143 stores data for identifying a cell detected as a handover target by the cell detection unit 17. Note that a cell identifier (Cell Identity) used for identifying a radio base station or the like and data stored in the cell ID 143 may be stored in association with each other. In the figure, the data stored in the cell ID 143 is the cell ID “1” or the like.

  For example, as shown in the record 14-0, the time point “1” of the time 142 is assumed to be the time point when the cell with the number “0” of the history number 141 is detected. Thereafter, when a cell is detected by the cell detection unit 17, as shown in the record 14-1, the time 142 stores the elapsed time from the time of the record 14-0 ("100" in the record 14-1). Then, the data (1 in the record 14-1) for identifying the newly detected cell is stored in the cell ID 143.

<3.2 Loop list 15>
Further, as shown in FIG. 4B, the loop list 15 includes a cell in which a movement loop has occurred within a certain time in the movement of the wireless communication terminal 100 and the handover by the wireless communication terminal 100 is inhibited. A list is shown.

  The loop list 15 stores data for identifying cells. The data for identifying the cell corresponds to the data stored in the cell ID 143 of the history information 14.

<4 Operation of Wireless Communication Terminal 100>
An operation of the wireless communication terminal 100 will be described.

<Outline of Operation of 4.1 Wireless Communication Terminal 100>
FIG. 5 is a flowchart showing the operation of the control unit 16 of the wireless communication terminal 100.

  As shown in the figure, the control unit 16 writes the cell ID and time of the current cell to which the wireless communication terminal 100 is connected in the history information 14 (S501).

  The control unit 16 causes the cell detection unit 17 to detect a cell that matches the measurement report transmission trigger (S503). At this time, the cell detection unit 17 writes the cell ID of the cell that matches the measurement report transmission trigger to the history information 14, and the elapsed time from the time when the number “0” of the history number 141 in the history information 14 is written is the history information. 14 is written.

  When the cell is detected by the cell detection unit 17, the control unit 16 determines whether the HO determination unit 18 should perform a handover with the cell (S505). The process of step S505 will be described later.

  The control unit 16 executes processing according to the determination result in step S505 by the HO control unit 19. If it is determined that the handover should be performed (S507: YES), the HO control unit 19 proceeds to step S509. If it is determined in step S505 that the handover should not be performed (S507: NO), the process returns to step S503.

  When the HO determination unit 18 determines that the handover should be performed (S507: YES), the control unit 16 clears the registered contents of the history information 14 and the loop list 15 (S509).

  Subsequently, the control unit 16 executes handover for the cell determined to be handed over by the HO control unit 19. Specifically, the HO control unit 19 executes the handover shown in FIG. 3 by transmitting a Measurement Report to the currently connected cell (S511).

<4.2 Determination Process by HO Determination Unit 18>
The process in step S505 described above will be described in detail.

FIG. 6 is a flowchart showing the operation of the HO determination unit 18.
As shown in the figure, the HO determination unit 18 determines whether there is a list of cells in which a loop of movement occurs in the loop list 15 (S601). A method for creating the loop list 15 will be described later.

<4.2.1 When there is a list of cells in the loop list 15>
If there is a list of cells in which a movement loop has occurred (S601: YES), the HO determination unit 18 records the previous record at the time of the previous detection, that is, the record written in the history information 14 in step S503. It is determined whether a predetermined time or more has elapsed from the time indicated in FIG. That is, the difference between the time indicated by the time 142 of the latest record written in the history information 14 in step S503 and the time indicated by the time 142 of the previous record is equal to or greater than a predetermined threshold (for example, several seconds have elapsed) Or not).

  If it is determined in step S602 that a predetermined time or more has elapsed since the previous detection time (S602: YES), the HO determination unit 18 determines that a handover should be performed (S611).

  If it is determined in step S602 that the predetermined time or more has not elapsed since the previous detection time (S602: NO), the HO determination unit 18 considers that the loop list 15 is valid, and the cell detected in step S503 is not detected. It is determined whether it is included in the loop list 15 (S603).

  If it is determined in step S603 that the cell detected by the cell detection unit 17 is not included in the loop list 15 (S603: NO), the HO determination unit 18 determines that a handover should be performed (S611).

  In step S603, if the HO determination unit 18 determines that the cell detected by the cell detection unit 17 is included in the loop list 15 (S603: YES), the communication quality of the currently connected cell is within the allowable range. Is determined (S609). Specifically, in this embodiment, if the signal strength (RSRP) of the currently connected cell is greater than or equal to a predetermined threshold, the communication quality is determined to be within an acceptable range (S609: YES), Then, it is determined that the communication quality is not within the allowable range (S609: NO).

  In step S609, if the communication quality of the currently connected cell is not within the allowable range (S609: NO), the HO determination unit 18 determines that the handover should be performed (S611).

  In step S609, if the communication quality of the currently connected cell is within the allowable range (S609: YES), the HO determination unit 18 determines that the handover should not be performed (S613).

<4.2.2 When there is no list of cells in the loop list 15>
A case where it is determined in step S601 that there is no cell list in the loop list 15 (S601: NO) will be described.

  In this case, the HO determination unit 18 determines whether or not the cell detected in step S503 is included in the history information 14, that is, is a cell detected in the past and a movement loop has occurred (S605). ). This process will be described later.

  If it is determined in step S605 that the cell is not included in the history information 14 (S605: NO), the HO determination unit 18 determines that a handover should be performed (S611).

  If it is determined in step S605 that the cell is included in the history information 14 (S605: YES), it is considered that a movement loop has occurred, and the loop list 15 is created (S607). Thereafter, the process proceeds to step S609 and the same process as described above is performed.

Here, the process of step S605 will be described in detail.
FIG. 7 is a diagram illustrating processing in which the HO determination unit 18 determines whether a movement loop has occurred and creates the loop list 15.

  In the example of FIG. 7, the cell (cell ID: 1) detected in step S503 is written as the latest cell in the number “4” of the history number 141.

  The HO determination unit 18 searches in the history information 14 whether a cell having the same ID has been detected in the past in the numerical order from the latest detection history of the latest cell (procedure 1). In the illustrated example, the search is performed with reference to “2” “1” and the cell ID 143 in order from the number “3” of the history number 141.

  As a result of the search, if a cell with the same ID has been detected in the past (procedure 2), the HO determination unit 18 retains the number of the history number 141 (procedure 3), and the latest detection history from that number is stored. Cells up to the number of the history number 141 are included in the loop list 15 (procedure 4). In the illustrated example, the cell ID: 1 is detected in the number “1” of the history number 141 (procedure 2), and the number “1” of the history number 141 is held (procedure 3). The cells indicated by the cell ID 143 from the held number “1” to the latest detection history number “3” are set as elements of the loop list 15 (procedure 4).

  On the other hand, if all the histories are searched and a cell having the same ID is not detected, the HO determination unit 18 determines that the cell detected in step S503 is not included in the history information 14 (S605: NO). ).

<4.3 Specific example of moving between two cells>
Here, the case of being in a loop moving between two cells will be specifically described with reference to the drawings.

FIG. 8 is a diagram showing a loop between two cells.
It is assumed that the cell ID of the base station 200 is “1”, the cell ID of the base station 300 is “2”, and the cell ID of the base station 400 is “3”. It is assumed that the radio communication terminal 100 moves frequently between the base station 300 and the base station 400.

  In the figure, a part of the history information 14 is shown. As shown in the figure, the wireless communication terminal 100 repeats the movement between the cell IDs “3” and “2”, and a movement loop occurs. By the operation of the wireless communication terminal 100 described above, the wireless communication terminal 100 detects a loop at the time of detecting a cell related to the number “4” of the history number 141 (S605: YES), and creates the loop list 15 ( S607). The created loop list 15 includes cell IDs “3” and “2”.

  Thereafter, each time the cell shown in the loop list 15 is detected (S603: YES), the radio communication terminal 100 goes through a predetermined process (step S609, etc.) and does not execute handover until a cell not included in the loop is detected. (Step S611, Step S507: NO).

  The wireless communication terminal 100 executes the handover by detecting the cell with the cell number “1” with the history number 141 number “9”, that is, the cell not included in the loop list 15 (S603: NO) (step S611). Step S511).

<4.4 Specific example when moving between three cells>
As another example, a case where a loop moves between three cells will be specifically described with reference to the drawings.

FIG. 9 is a diagram showing a loop between three cells.
As in FIG. 8, the cell ID of the base station 200 is “1”, the cell ID of the base station 300 is “2”, and the cell ID of the base station 400 is “3”. In the example of FIG. 9, description will be made assuming that the wireless communication terminal 100 frequently moves between the base station 200, the base station 300, and the base station 400.

  A part of the history information 14 is shown in FIG. As shown in the history information 14, the wireless communication terminal 100 repeats the movement of the cell IDs “1”, “2”, and “3”, and a movement loop occurs.

  The wireless communication terminal 100 detects a loop at the time point of the history number 141 number “4” (S605: YES), and creates the loop list 15 (S607). The created loop list 15 includes cell IDs “1”, “2”, and “3”.

  Thereafter, the wireless communication terminal 100 suppresses the handover until the cell having the history number 141 of “9” and the cell ID “4”, that is, the cell not included in the loop list 15 is detected (steps S611 and S507). NO). When a cell with the cell ID “4”, that is, a cell not included in the loop list 15 is detected, a handover is executed (steps S611 and S511).

<5 Modification>
As described above, an embodiment of the invention has been described. In addition, the following modifications can be made.

(Handover between multiple communication methods)
In the description of the above embodiment, the handover control of the radio communication terminal 100 when the base station performs communication corresponding to the LTE scheme has been described. In addition to this, at the time of handover to a base station of a different communication method, processing (such as transmission of signal quality measurement results from the base station) that triggers the start of handover from the radio communication terminal 100 is similarly stopped. Similarly to the above, frequent occurrence of handover can be suppressed.

  For example, the same operation as described above can be performed at the time of handover from LTE to a 3G system such as W-CDMA (Wideband Code Division Multiple Access). Note that handover between different systems is called inter-RAT (Radio Access Technology) handover.

  The embodiment disclosed this time must be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be used for a wireless communication terminal in a mobile communication system or the like.

  DESCRIPTION OF SYMBOLS 1 Mobile communication system, 6 Display part, 7 Voice output part, 8 Voice input part, 9 Operation part, 10 Baseband part, 13 Storage part, 14 History information, 15 Loop list, 16 Control part, 17 Cell detection part, 18 HO determination unit, 19 HO control unit, 21 CDMA wireless communication unit, 31 LTE wireless communication unit, 41 WiFi wireless communication unit, 22 CDMA antenna, 32 LTE antenna, 42 WiFi antenna, 23 CDMA processing unit, 33 LTE processing unit, 43 WiFi processing unit, 100 wireless communication terminal, 200, 300, 400 base station, 201, 301, 401 cell.

Claims (12)

A wireless communication terminal in a mobile communication system,
Based on the communication quality with the radio base station, a detection unit that detects a cell to be handed over,
A storage unit for storing history information indicating a history of identifiers of the cells detected by the detection unit;
When the detection unit detects a cell, a determination unit that determines whether to perform handover to the cell related to the detection based on the identifier of the cell related to the detection and the history indicated in the history information;
A control unit that executes control to suppress handover to a cell related to the detection when the determination unit determines that the handover should not be performed;
A wireless communication terminal. Control of handover suppression by the control unit is performed by stopping communication processing from the wireless communication terminal to the wireless base station, which is included in the communication procedure for executing handover.
The wireless communication terminal according to claim 1. The handover is started by transmitting a predetermined report including the strength of the radio signal transmitted from the radio base station from the radio communication terminal to the radio base station,
Control of handover suppression by the control unit is performed by stopping transmission of the predetermined report to a radio base station.
The wireless communication terminal according to claim 2. The control unit, when the communication quality in the cell is below a predetermined threshold, cancels the control to suppress the handover,
The wireless communication terminal according to claim 1. The determination unit determines that the cell should not be handed over when the detected cell is included in the history indicated in the history information;
The wireless communication terminal according to claim 1. The determination unit should not be handed over to the predetermined cell group when the terminal is in a loop state that repeats movement of the predetermined cell group within a predetermined time based on the history indicated in the history information. Judgment,
The cell group in the loop state is formed by the cell and one or more cells detected after the time when the cell was detected in the past when the detected cell is included in the history.
The wireless communication terminal according to claim 1. The storage unit stores a loop list indicating cells for suppressing the execution of handover by the own terminal,
The determination unit updates the loop list based on the history indicated in the history information, and determines that the cell should not be handed over when the detected cell is included in the loop list.
The wireless communication terminal according to claim 1. The determination unit, when the detected cell is included in the history indicated in the history information, registers the cell and cells detected after the time when the cell was detected in the past in the loop list,
The wireless communication terminal according to claim 7. When the determination unit detects a cell not included in the loop list by the detection unit, the determination unit erases the registered content of the loop list and determines that a handover to a cell not included in the loop list is to be performed.
The wireless communication terminal according to claim 8. The determination unit determines that a handover to the detected cell should be performed regardless of registered contents of the loop list when a predetermined time has elapsed since the loop list was updated.
The wireless communication terminal according to claim 7. A method for controlling a wireless communication terminal in a mobile communication system, comprising:
The wireless communication terminal includes a wireless communication module, a memory, and a processor.
The method
The processor detecting a cell to be handed over based on communication quality of wireless communication with a wireless base station by the wireless communication module;
The processor storing history information indicating a history of the detected cell identifier in a memory;
When the processor detects a cell, the processor determines whether to hand over to the cell related to the detection based on the identifier of the cell related to the detection and the history shown in the history information;
Performing control to suppress handover to a cell for detection when the processor determines that it should not be handed over,
Method. A program for controlling a wireless communication terminal in a mobile communication system,
The wireless communication terminal includes a wireless communication module, a memory, and a processor.
The program is stored in the processor.
Detecting a cell to be handed over based on the communication quality of wireless communication with a wireless base station by the wireless communication module;
Storing history information indicating a history of the identifier of the detected cell in a memory;
When a cell is detected, determining whether to hand over to the cell related to the detection based on the identifier of the cell related to the detection and the history shown in the history information;
Executing a control to suppress handover to the cell involved in the detection when it is determined that the handover should not be performed,
program.

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