JP2011223116A - Mobile station and communication control method - Google Patents

Abstract

An object of the present invention is to reduce the number of measurement reports while appropriately determining events during carrier aggregation.
A mobile station UE according to the present invention includes a measurement reference CC selection unit 104 that selects a CC that satisfies a selection condition from two or more CCs as a measurement reference CC, and a cell or adjacent cell in the measurement reference CC. A determination unit that determines that the radio base station eNB should notify the measurement result when the radio quality of the cell satisfies a predetermined condition while the predetermined timer is activated, 106 does not change the Measurement Reference CC even when the CC satisfying the selection condition is changed while the predetermined timer is activated.
[Selection] Figure 2

Description

  The present invention relates to a mobile station and a communication control method.

  Wideband code division multiple access (WCDMA) method, high-speed downlink packet access (HSDPA) method, high-speed uplink packet access (HSUPA: High-PumpUpSedUpSpUcP) A communication system that is a successor of the system, that is, a long term evolution (LTE) system was studied by the WCDMA standardization organization 3GPP, and specification work was performed.

  Also, as a communication method succeeding the LTE method, the LTE-advanced method is being studied by 3GPP. Non-Patent Document 1 summarizes the requirements for the LTE-advanced scheme.

  In the LTE-advanced scheme, it is agreed that “carrier aggregation” is performed as a requirement.

  When “carrier aggregation” is performed, the mobile station UE can receive a downlink signal using a plurality of carriers at the same time, or can transmit an uplink signal using a plurality of carriers at the same time. Each carrier in the case where carrier aggregation is performed is called a component carrier (CC: Component Carrier).

  By the way, in a mobile communication system including a plurality of cells, a mobile station UE (User Equipment: user equipment) is configured to switch cells and continue communication when moving from one cell to another cell. ing. Such cell switching is called “handover”.

  In general, in a mobile communication system, a mobile station UE moves to an adjacent cell, and in the mobile station UE, the radio quality of a signal from an adjacent cell is better than the radio quality of a signal from a serving cell. In this case, the mobile station UE is configured to perform handover to an adjacent cell.

  Note that, for example, the received power of the signal is used as the radio quality of the signal. Here, more specifically, the received power of the signal may be, for example, the received power (RSRP: Reference Signal Received Power) of the downlink reference signal (Reference Signal) transmitted from the neighboring cell or the serving cell. Good (see Non-Patent Documents 2 and 3 for the definition of RSRP).

  As the radio quality of the signal, instead of RSRP, the reception quality of the downlink reference signal (RSRQ: Reference Signal Received Quality), the SIR (RS-SIR) of the downlink reference signal, CQI (Channel Quality) Indicator, CSI (Channel State Information), or the like may be used.

  An example of such a handover procedure will be specifically described with reference to FIG. 9 and FIG. In the following description, the received power (RSRP) of the signal is used as the radio quality of the signal.

  As shown in FIG. 9, in step S1, the mobile station UE measures received power of signals from the serving cell (in-communication cell) and neighboring cells. Further, the mobile station UE may perform a cell search in parallel with the measurement in order to detect a neighboring cell that has not been detected. The cell search and the measurement of the radio quality (reception power) of the serving cell and the neighboring cell in this process may be collectively referred to as measurement.

  In step S2, the mobile station UE determines whether or not the received power of the signal from the adjacent cell satisfies the following (Equation 1).

  Received power of signal from neighboring cell> Received power of signal from serving cell + Hysteresis (Equation 1)

  If it is determined that (Equation 1) is satisfied, in step S2, the mobile station UE notifies the network of an event A3 for reporting the above measurement result. Here, the network is specifically a radio base station eNB, for example.

  Specifically, as shown in FIG. 10, the mobile station UE measures received power of signals from the serving cell (cell A) and the neighboring cell (cell B) to be monitored, and the “hysteresis” notified in advance. [DB] ”and“ Time To Trigger (TTT) [ms] ”are used to determine whether or not to notify the measurement result. The peripheral cell may be referred to as an adjacent cell.

  That is, in FIG. 10, the received power (radio quality) of the signal from the cell B is higher than the received power (radio quality) of the signal from the cell A for the predetermined period “TTT” or more. When the mobile station UE continues, the mobile station UE determines that the above measurement result (MR: Measurement Report) should be notified.

  Here, “hysteresis” is a value provided in order that handover from a serving cell to an adjacent cell does not frequently occur at a cell boundary, and may be a positive value or a negative value. Value is set.

  In step S3, when the notification of event A3 is received, the network determines that the mobile station UE should perform handover to the cell related to event A3 received.

  In addition, (Formula 1) may take the form of the following (Formula 2). In the case of (Formula 2), both hysteresis and offset operate in a hysteresis manner.

  Received power of signal from neighboring cell-Hysteresis> Received power of signal from serving cell + Offset (Equation 2)

  In the LTE system, in addition to the above-described event A3, the following event A1, event A2, event A4, and event A5 are defined.

  For example, when the radio quality of the signal from the serving cell satisfies the following (Equation 3), that is, when the radio quality from the serving cell is higher than the first threshold, the mobile station UE reports the above measurement result. Event A1 to notify the network.

  Received power of signal from serving cell> First threshold value (Expression 3)

Here, the event A1 is notified from the mobile station UE to the radio base station eNB as a Measurement Report.
Alternatively, for example, when the radio quality of the signal from the serving cell satisfies the following (Equation 4), that is, when the radio quality from the serving cell is smaller than the second threshold, the mobile station UE performs the above measurement result. Is notified to the network.

  Received power of signal from serving cell <second threshold value (Expression 4)

  Here, the event A2 is notified from the mobile station UE to the radio base station eNB as a Measurement Report.

  Alternatively, for example, when the radio quality of the signal from the neighboring cell satisfies the following (Equation 5), that is, when the radio quality from the neighboring cell is larger than the third threshold, the mobile station UE An event A4 for reporting the measurement result is notified to the network.

  Received power of signal from neighboring cell> Third threshold value (Expression 5)

  Here, the event A4 is notified from the mobile station UE to the radio base station eNB as a Measurement Report.

  Alternatively, for example, when the radio quality of the signal from the serving cell and the radio quality of the signal from the neighboring cell satisfy the following (Equation 6), that is, the radio quality of the signal from the serving cell becomes lower than the fourth threshold value. And when the radio quality of the signal from an adjacent cell is larger than a 5th threshold value, the mobile station UE notifies the event A5 for reporting the above-mentioned measurement result with respect to a network.

The received power of the signal from the serving cell <the fourth threshold, and
Received power of signal from neighboring cell> fifth threshold
... (Formula 6)

  Here, the event A5 is notified from the mobile station UE to the radio base station eNB as a Measurement Report.

  For example, the event A1 and the event A2 may be used by the radio base station eNB to determine the timing for starting and stopping the Measurement Gap for the mobile station UE.

  When performing carrier aggregation, in general, the mobile station UE performs measurement of received power of signals from the above-described serving cell and adjacent cells, determination of an event, and transmission of measurement report for each CC.

  Here, when performing carrier aggregation, for each CC, when measuring the received power of the signal from the serving cell and the neighboring cell, determining an event, and transmitting a measurement report, the number of measurement reports is CC. There is a problem of increasing by the number of.

  In order to solve such a problem, it has been proposed to define a measurement reference carrier as a reference carrier for measurement among a plurality of CCs, and to perform the above-described event determination using the measurement reference carrier (non-patent document). Reference 4).

  For example, in this proposal, it is proposed that a CC having the best radio quality among a plurality of CCs is a Measurement Reference Component Carrier (CC).

  Or conversely, the CC having the worst radio quality among a plurality of CCs may be defined as a Measurement Reference Component Carrier (CC).

  The determination of event A3 using Measurement Reference CC will be described with reference to FIGS.

  In FIG.11 and FIG.12, the mobile station UE is carrier # 3 (from the state which is performing the carrier aggregation using CC # 1 (cell # 1-A) and CC # 2 (cell # 1-B). An inter-frequency handover is performed using event A3 so that a transition is made to a state where communication is performed using cell # 2-C).

  In the case of FIG. 11, the Measurement Reference CC is not used, so the Measurement Report regarding the event A3 of CC # 1 (cell # 1-A) and carrier # 3 (cell # 2-C) and CC # 2 (cell # 1) -B) and Measurement Report regarding event A3 of carrier # 3 (cell # 2-C) are transmitted from the mobile station UE to the radio base station eNB. That is, in the above-described case, two Measurement Reports are transmitted from the mobile station UE to the radio base station eNB.

  On the other hand, in the case of FIG. 12, CC # 2 (cell # 1-B) with the best radio quality is set as the Measurement Reference CC, and this CC # 2 (cell # 1-B) and carrier # 3 (cell # 2) are set. -C) Measurement Report related to event A3 is transmitted from the mobile station UE to the radio base station eNB. In this case, since the number of Measurement Reports may be one, the number of Measurement Reports is reduced compared to the example of FIG.

3GPP TS36.913 V8.0.1 3GPP TS36.300 V8.5.0 3GPP TS36.214 V8.3.0 3GPP contribution R2-100122

  As described above, when performing carrier aggregation, the mobile station UE performs measurement of radio quality of signals from the serving cell and neighboring cells, determination of events, and transmission of measurement reports for each CC. .

  Then, in the mobile station UE, it has been proposed to use a measurement reference CC in order to avoid an increase in the number of measurement reports when such an event is determined for each CC.

  However, in the determination of an event using the Measurement Reference CC, there is no provision on how to determine an event when the Measurement Reference CC is changed due to a change in radio quality related to each CC. There was a problem.

  This problem will be further described with reference to FIGS. FIGS. 13 and 14 are diagrams illustrating temporal variations in the radio quality of each cell in the handover illustrated in FIGS. 11 and 12.

  In the example of FIG. 13, since the magnitude relationship between the radio qualities of the cell # 1-B and the cell # 1-A does not change, the Measurement Reference CC does not change. That is, in the example of FIG. Becomes the cell of Measurement Reference CC.

  Therefore, in the example of FIG. 13, at time T1, a time-to-trigger (TTT) that is a timer of event A3 is activated for cell # 1-B that is a cell of Measurement Reference CC, and at time T2, TTT expires.

  On the other hand, in the example of FIG. 14, the magnitude relationship between the radio qualities of cell # 1-B and cell # 1-A changes at time T2. That is, Measurement Reference CC, which is the cell with the best radio quality, is changed from CC # 2 to CC # 1 at time T2.

  On the other hand, similarly to the example of FIG. 13, at the time T1, the TTT of the event A3 related to the cell # 1-B and the cell # 2-C, which are measurement reference CCs, is activated.

  However, in the existing LTE-Advanced method, the operation after time T2 is not defined.

  Accordingly, the present invention has been made in view of the above-described problems, and by reducing the number of measurement reports while appropriately determining events during carrier aggregation, the efficiency of the system and the stability of connectivity are improved. An object of the present invention is to provide a mobile station and a communication control method capable of realizing the above.

  A first feature of the present invention is a mobile station capable of communicating with a radio base station using two or more carriers, and for each carrier in the two or more carriers, a cell in communication or adjacent A measurement unit configured to measure the radio quality of the cell, and a reference carrier selection unit configured to select a carrier that satisfies a selection condition as a reference carrier for measurement from the two or more carriers. The measurement result in the measurement unit is notified to the radio base station when the radio quality of the cell in communication or the neighboring cell on the reference carrier for measurement satisfies a predetermined condition while a predetermined timer is activated. A determination unit configured to determine that the measurement should be performed; and when the determination unit determines that the measurement result should be notified to the radio base station. A transmitter configured to transmit to the radio base station, and the determination unit is configured when the carrier that satisfies the selection condition is changed while the predetermined timer is activated. Even if it exists, it is set as the summary that it is comprised so that the said reference carrier for a measurement may not be changed.

  A second feature of the present invention is a mobile station capable of communicating with a radio base station using two or more carriers, and for each carrier in the two or more carriers, a cell in communication or adjacent A measurement unit configured to measure the radio quality of the cell, and a reference carrier selection unit configured to select a carrier that satisfies a selection condition as a reference carrier for measurement from the two or more carriers. The measurement result in the measurement unit is notified to the radio base station when the radio quality of the cell in communication or the neighboring cell on the reference carrier for measurement satisfies a predetermined condition while a predetermined timer is activated. A determination unit configured to determine that the measurement should be performed; and when the determination unit determines that the measurement result should be notified to the radio base station. A transmitting unit configured to transmit to the radio base station, and the determination unit is configured to change a carrier that satisfies the selection condition while the predetermined timer is activated. The gist of the invention is that the measurement reference carrier is changed and the predetermined timer is continuously started.

  A third feature of the present invention is a mobile station capable of communicating with a radio base station using two or more carriers, and for each carrier in the two or more carriers, a cell in communication or adjacent A measurement unit configured to measure the radio quality of the cell, and a reference carrier selection unit configured to select a carrier that satisfies a selection condition as a reference carrier for measurement from the two or more carriers. The measurement result in the measurement unit is notified to the radio base station when the radio quality of the cell in communication or the neighboring cell on the reference carrier for measurement satisfies a predetermined condition while a predetermined timer is activated. A determination unit configured to determine that the measurement should be performed; and when the determination unit determines that the measurement result should be notified to the radio base station. A transmitting unit configured to transmit to the radio base station, and the determination unit is configured to change a carrier that satisfies the selection condition while the predetermined timer is activated. The gist of the invention is that the measurement reference carrier is changed and the predetermined timer is reset.

  According to a fourth aspect of the present invention, there is provided a communication control method in a mobile station capable of communicating with a radio base station using two or more carriers, wherein communication is performed for each carrier in the two or more carriers. A first step of measuring the radio quality of a middle cell or an adjacent cell; a second step of selecting a carrier that satisfies a selection condition from the two or more carriers as a reference carrier for measurement; and the reference carrier for measurement When the wireless quality of the cell in communication or the neighboring cell satisfies a predetermined condition while the predetermined timer is activated, it is determined that the measurement result in the first step should be notified to the wireless base station When it is determined in the third step and the third step that the measurement result should be notified to the radio base station, the measurement result is sent to the radio base station. And when the carrier satisfying the selection condition is changed while the predetermined timer is activated in the third step, the measurement reference carrier is changed. In addition, the gist is to continue the activation of the predetermined timer.

  As described above, according to the present invention, the efficiency of the system and the stability of the connectivity can be realized by reducing the number of measurement reports while appropriately determining events during carrier aggregation. A mobile station and a communication control method can be provided.

FIG. 3 is a functional block diagram of a mobile station according to the first embodiment of the present invention. It is a figure for demonstrating operation | movement of the mobile station which concerns on the 1st Embodiment of this invention. 3 is a flowchart for explaining an operation of the mobile station according to the first embodiment of the present invention. It is a figure for demonstrating operation | movement of the mobile station which concerns on the 2nd Embodiment of this invention. It is a figure for demonstrating operation | movement of the mobile station which concerns on the 2nd Embodiment of this invention. 6 is a flowchart for explaining an operation of the mobile station according to the second embodiment of the present invention. It is a figure for demonstrating operation | movement of the mobile station which concerns on the 3rd Embodiment of this invention. 7 is a flowchart for explaining an operation of a mobile station according to the third embodiment of the present invention. 6 is a flowchart for explaining the operation of a conventional mobile communication system. It is a figure for demonstrating operation | movement of the conventional mobile communication system. It is a figure for demonstrating operation | movement of the conventional mobile communication system. It is a figure for demonstrating operation | movement of the conventional mobile communication system. It is a figure for demonstrating operation | movement of the conventional mobile communication system. It is a figure for demonstrating operation | movement of the conventional mobile communication system.

(Mobile communication system according to the first embodiment of the present invention)
The configuration of the mobile communication system according to the first embodiment of the present invention will be described with reference to FIGS. The mobile communication system according to the present embodiment is an LTE-Advanced mobile communication system.

  The mobile station UE according to the present embodiment is configured to be able to communicate with the radio base station eNB using two or more CCs, that is, configured to be able to perform carrier aggregation. Yes.

  As illustrated in FIG. 1, the mobile station UE includes a measurement unit 102, a measurement reference CC selection unit 104, a determination unit 106, a measurement report transmission unit 108, and a measurement control signal reception unit 110.

  The Measurement control signal receiving unit 110 is configured to receive a Measurement Control (Measurement control signal) transmitted by the radio base station eNB.

  Here, the Measurement Control is used to notify the mobile station UE of information related to the measurement target cell of the radio quality (Measurement Object), information related to the measurement report transmission method including the measurement result (Reporting Configuration), and the like. It is a control signal.

  Note that the Measurement Control may be referred to as Measurement Configuration or Measurement Config.

  The measuring unit 102 is configured to measure the radio quality of a cell in communication (serving cell) or an adjacent cell in accordance with the above-described Measurement Control.

  Here, when carrier aggregation is performed, the measurement unit 102 is configured to measure the radio quality of a cell in communication or an adjacent cell for each CC in two or more CCs.

  The Measurement Reference CC selection unit 104 is configured to select a CC satisfying the selection condition as a Measurement Reference CC from two or more CCs.

  For example, the Measurement Reference CC selection unit 104 may be configured to select the CC with the best radio quality as the CC that satisfies the selection condition.

  Alternatively, the Measurement Reference CC selection unit 104 may be configured to select the CC with the lowest radio quality as the CC that satisfies the selection condition. In the following description, as an example, the case where the CC with the highest radio quality is selected as the CC that satisfies the selection condition will be described.

  The determination unit 106 should notify the radio base station eNB of the measurement result in the measurement unit 102 when the radio quality of the cell in communication or the neighboring cell satisfies the predetermined condition while the predetermined timer is activated. It is configured to determine that there is.

  Here, the determination unit 106 may use the wireless quality of the communicating cell in the above-mentioned Measurement Reference CC as the wireless quality of the communicating cell.

  In the following, as a more specific example, consider a case where there are three component carriers performing carrier aggregation.

  Here, it is assumed that the three component carriers are called component carrier # 1, component carrier # 2, and component carrier # 3, respectively. In addition, it is assumed that the cells that are communicating with each component carrier are called cell # 1, cell # 2, and cell # 3, respectively.

  In this case, the measurement reference CC selection unit 104 selects the measurement reference CC from the component carrier # 1, the component carrier # 2, and the component carrier # 3 as described above, and the determination unit 106 uses the measurement reference CC in the measurement reference CC. The wireless quality of the cell is used as the wireless quality of the above-described communicating cell.

  That is, when component carrier # 2 is selected as the measurement reference CC, the determination unit 106 determines that the radio quality of the cell # 2 and the radio quality of the adjacent cell satisfy a predetermined condition while the predetermined timer is activated. When it is satisfied, it may be determined that the measurement result in the measurement unit 102 should be notified to the radio base station eNB.

  In the above-described example, the determination unit 106 has shown the case where the wireless quality of the cell in the above-mentioned Measurement Reference CC is used as the wireless quality of the cell in communication. The radio quality of neighboring cells in the Measurement Reference CC of the same may be used.

  That is, a plurality of carriers that are candidates for selection as the Measurement Reference CC may be designated in advance, and the determination unit 106 may select the Measurement Reference CC from the plurality of carriers.

  Here, the plurality of carriers to be selected as the measurement reference CC may be component carriers on which carrier aggregation is performed, or may not be component carriers on which carrier aggregation is performed. Alternatively, some of the plurality of carriers that are candidates for selection as the Measurement Reference CC may be component carriers on which carrier aggregation is performed.

  Below, the example of the operation | movement which determines with the determination part 106 mentioned above should notify the radio base station eNB of the measurement result in the measurement part 102 is shown. In the following operation, the radio quality of the cell in communication in the above-mentioned Measurement Reference CC may be used as the radio quality of the cell in communication. In the following operation, the wireless quality of the neighboring cell in the above-mentioned Measurement Reference CC may be used as the wireless quality of the neighboring cell.

  For example, the determination unit 106 determines that the wireless quality of the neighboring cell is better than the wireless quality of the communicating cell by a predetermined offset, that is, the above (Expression 1) or (Expression 2) is satisfied. When it is, it may be configured to determine that the wireless quality of the cell in communication or the neighboring cell satisfies a predetermined condition (event A3).

  Further, when the wireless quality of the cell in communication becomes better than the first threshold, that is, when it is determined that the above (Equation 3) is satisfied, the determination unit 106 determines whether the cell in communication or the adjacent cell The wireless quality may be determined to satisfy a predetermined condition (event A1).

  In addition, when the wireless quality of the cell in communication becomes worse than the second threshold, that is, when it is determined that the above (Equation 4) is satisfied, the determination unit 106 determines whether the cell in communication or the adjacent cell The wireless quality may be determined to satisfy a predetermined condition (event A2).

  Further, when the wireless quality of the adjacent cell becomes better than the third threshold, that is, when it is determined that the above (Equation 5) is satisfied, the determination unit 106 determines whether the wireless of the cell in communication or the adjacent cell It may be configured to determine that the quality satisfies a predetermined condition (event A4).

  Further, when the wireless quality of the cell in communication becomes worse than the fourth threshold and the wireless quality of the neighboring cell becomes better than the fifth threshold, the determination unit 106 satisfies the above (Formula 6). If it is determined that the wireless quality of the cell in communication or the neighboring cell satisfies the predetermined condition (event A5), it may be configured.

  Alternatively, the determination unit 106 is configured to determine that the wireless quality of a cell in communication or an adjacent cell satisfies a predetermined condition when the above measurement result is a transmission timing when the measurement result is periodically transmitted. Also good.

  The predetermined timer may be a time-to-trigger (TTT) or another type of timer. Here, the TTT is activated when the wireless quality of the cell in communication or the adjacent cell satisfies a predetermined condition, and is stopped when the wireless quality of the cell in communication or the adjacent cell no longer satisfies the predetermined condition. It is configured as follows.

  The Measurement Report transmission unit 108 performs measurement by the measurement unit 102 on the radio base station eNB according to the measurement control described above when the determination unit 106 determines that the measurement result should be notified to the radio base station eNB. It is configured to send a Measurement Report containing the result.

  Here, in the present embodiment, the determination unit 106 does not change the Measurement Reference CC even when the CC satisfying the selection condition is changed while the predetermined timer (TTT) is activated. It is configured.

  The operation in the determination unit 106 will be described with reference to FIG. In FIG. 2, cell # 1-A and cell # 1-B exist as cells in a component carrier performing carrier aggregation, and cell # 2-C exists as an adjacent cell.

  Here, at time T1, the determination unit 106 activates the TTT of the event A3 for the cell # 1-B and the neighbor cell # 2-C that are the measurement reference CCs, and then at the time T2 when the TTT is activated. Even if the radio quality of the cell # 1-A is higher than the radio quality of the cell # 1-B, the TTT is continuously started without changing the Measurement Reference CC. .

  In this case, the determination unit 106 determines whether or not the determination condition of the event A3 while the TTT is activated satisfies the measurement reference CC that is not changed, that is, the radio quality and the cell of the cell # 1-B This is based on the wireless quality of # 2-C.

  Then, after the expiration of the TTT, the Measurement Report transmission unit 108 is configured to transmit a Measurement Report to the radio base station eNB.

  Hereinafter, the operation of the mobile station UE according to the present embodiment, that is, the communication control method will be described with reference to FIG.

  As shown in FIG. 3, in step S101, the measurement unit 102 measures the radio quality of a cell in communication or an adjacent cell as described above. In step S102, the Measurement Reference CC selection unit 104 performs measurement as described above. , And select Measurement Reference CC.

  In step S <b> 103, the determination unit 106 determines whether or not the measurement reference CC should be changed based on the measurement result of the radio quality of the cell in communication or the neighboring cell.

  If it is determined that the Measurement Reference CC should not be changed, this operation ends. If it is determined that the Measurement Reference CC should be changed, the operation proceeds to step S104.

  In step S104, the determination unit 106 determines whether or not the TTT is being activated. If it is determined that the TTT is not activated, the operation proceeds to step S106. If it is determined that the TTT is activated, the operation proceeds to step S105.

  In step S105, the determination unit 106 continues the activation of the TTT and does not change the Measurement Reference CC.

  In step S106, the determination unit 106 changes the Measurement Reference CC.

  According to the mobile communication system according to the present embodiment, the mobile station UE does not change the Measurement Reference CC even when the CC satisfying the selection condition is changed while the TTT is activated. By configuring, it is possible to avoid resetting the determination of the event accompanying the change of the Measurement Reference CC, and it is possible to reduce the number of Measurement Reports while appropriately determining the event at the time of carrier aggregation.

(Mobile communication system according to the second embodiment of the present invention)
With reference to FIG. 4 thru | or FIG. 6, the structure of the mobile communication system which concerns on the 2nd Embodiment of this invention is demonstrated. Hereinafter, the mobile communication system according to the present embodiment will be described by focusing on differences from the mobile communication system according to the first embodiment described above.

  In the present embodiment, the determination unit 106 changes the Measurement Reference CC when the CC satisfying the selection condition is changed while a predetermined timer (for example, TTT) is activated, and the predetermined timer Configured to continue booting.

  The operation of the determination unit 106 will be described with reference to FIGS. 4 and 5. 4 and 5, cell # 1-A and cell # 1-B exist as cells in a component carrier performing carrier aggregation, and cell # 2-C exists as an adjacent cell.

  Here, at time T1, the determination unit 106 activates the TTT of the event A3 for the cell # 1-B and the neighbor cell # 2-C that are the measurement reference CCs, and then at the time T2 when the TTT is activated. When the radio quality of the cell # 1-A becomes higher than the radio quality of the cell # 1-B, the measurement reference CC is changed to the cell # 1-A and the TTT is started continuously. .

  In this case, the determination unit 106 determines whether or not the determination condition of the event A3 is satisfied while the TTT is activated, as to whether or not the changed Measurement Reference CC, that is, the radio quality of the cell # 1-A and the cell This is based on the wireless quality of # 2-C.

  Thereafter, in the example of FIG. 4, at time T3, the radio quality of the cell in communication (cell # 1-A) or the adjacent cell does not satisfy the predetermined condition (event A3), so the determination unit 106 stops TTT. Yes.

  On the other hand, in the example of FIG. 5, the measurement report transmission unit 108 is configured to transmit a measurement report to the radio base station eNB after the expiration of the TTT, that is, at time T4.

  Hereinafter, the operation of the mobile station UE according to the present embodiment, that is, the communication control method will be described with reference to FIG. As shown in FIG. 6, the operations in steps S201 to S204 and S206 are the same as the operations in steps S101 to S104 and S106 shown in FIG.

  In step S205, the determination unit 106 changes the Measurement Reference CC and continues the activation of the TTT.

  According to the mobile communication system according to the present embodiment, when the CC satisfying the selection condition is changed while the TTT is activated, the mobile station UE activates the TTT while changing the Measurement Reference CC. By being configured to continue, it is possible to avoid resetting the determination of an event due to a change in the Measurement Reference CC, and at the time of carrier aggregation, the number of Measurement Reports is reduced while appropriately determining the event. be able to.

(Mobile communication system according to the third embodiment of the present invention)
With reference to FIG.7 and FIG.8, the structure of the mobile communication system which concerns on the 3rd Embodiment of this invention is demonstrated. Hereinafter, the mobile communication system according to the present embodiment will be described by focusing on differences from the mobile communication system according to the first embodiment described above.

  In the present embodiment, the determination unit 106 changes the Measurement Reference CC when the CC satisfying the selection condition is changed while a predetermined timer (for example, TTT) is activated, and sets the predetermined timer. Configured to reset.

  The operation in the determination unit 106 will be described with reference to FIG. In FIG. 7, cell # 1-A and cell # 1-B exist as cells in a component carrier performing carrier aggregation, and cell # 2-C exists as an adjacent cell.

  Here, at time T1, the determination unit 106 activates the TTT of the event A3 for the cell # 1-B and the neighbor cell # 2-C that are the measurement reference CCs, and then at the time T2 when the TTT is activated. When the radio quality of the cell # 1-A becomes higher than the radio quality of the cell # 1-B, the measurement reference CC is changed to the cell # 1-A, and the TTT is reset.

  In this case, the determination of whether or not the determination condition of the event A3 while the TTT is activated in the determination unit 106 is once reset, and then the changed Measurement Reference CC, that is, the cell # 1- Based on the wireless quality of A and the wireless quality of cell # 2-C, the determination of event A3 is performed again.

  In other words, the determination unit 106 activates the TTT of the event A3 for the cell # 1-A and the neighbor cell # 2-C that are Measurement Reference CCs at time T2.

  Thereafter, after the expiration of the TTT reset at time T2, that is, at time T5, the Measurement Report transmission unit 108 is configured to transmit a Measurement Report to the radio base station eNB.

  Hereinafter, the operation of the mobile station UE according to the present embodiment, that is, the communication control method will be described with reference to FIG. As shown in FIG. 8, the operations in steps S301 to S304 and S306 are the same as the operations in steps S101 to S104 and S106 shown in FIG.

  In step S305, the determination unit 106 changes the Measurement Reference CC and resets the TTT.

  According to the mobile communication system according to the present embodiment, when the CC satisfying the selection condition is changed while the TTT is activated, the mobile station UE resets the TTT while changing the Measurement Reference CC. By configuring as described above, it is possible to determine an event regarding a specific Measurement Reference CC, and as a result, it is possible to prevent an event determination error or uncertainty due to a change of the Measurement Reference CC. Become. As a result, it is possible to reduce the number of measurement reports while appropriately determining events during carrier aggregation.

  The features of the embodiment described above may be expressed as follows.

  The first feature of the present embodiment is a mobile station UE that can communicate with a radio base station eNB using two or more CCs (carriers), and for each CC in the two or more CCs, The CC satisfying the selection condition is selected as a measurement reference CC (measurement reference carrier) from the measurement unit 102 configured to measure the radio quality of the cell in communication or the neighboring cell and two or more CCs. As for the measurement reference CC selection unit (reference carrier selection unit) 104 and the measurement reference CC configured in the above, the radio quality of the cell in communication or the neighboring cell satisfies the predetermined condition while the predetermined timer is activated The measurement result in the measurement unit 102 is transmitted to the radio base station eNB. When the determination unit 106 configured to determine that the measurement should be performed and the determination unit 106 determines that the radio base station eNB should be notified of the measurement result, the measurement result is transmitted to the radio base station eNB. A measurement report transmission unit (transmission unit) 108 configured to transmit, and the determination unit 106 is a case where the CC satisfying the selection condition is changed while the predetermined timer is activated. However, the gist is that it is configured not to change the Measurement Reference CC.

  A second feature of the present embodiment is a mobile station UE that can communicate with a radio base station eNB using two or more CCs, and is in communication with each CC in the two or more CCs. Alternatively, a measurement reference CC configured to select, as a measurement reference CC, a CC that satisfies a selection condition from the measurement unit 102 configured to measure the radio quality of an adjacent cell and two or more CCs Unit 104 and Measurement Reference CC, when the radio quality of a cell in communication or an adjacent cell satisfies a predetermined condition while a predetermined timer is activated, a measurement result in measurement unit 102 is transmitted to radio base station eNB. The determination unit 10 configured to determine that notification should be made And a measurement report transmission unit configured to transmit the measurement result to the radio base station eNB when the determination unit 106 determines that the measurement result should be notified to the radio base station eNB. The determination unit 106 is configured to change the Measurement Reference CC and continue the activation of the predetermined timer when the CC satisfying the selection condition is changed while the predetermined timer is activated. It is a summary.

  A third feature of the present embodiment is a mobile station UE that can communicate with a radio base station eNB using two or more CCs, and is in communication with each CC in the two or more CCs. Alternatively, a measurement reference CC configured to select, as a measurement reference CC, a CC that satisfies a selection condition from the measurement unit 102 configured to measure the radio quality of an adjacent cell and two or more CCs Unit 104 and Measurement Reference CC, when the radio quality of a cell in communication or an adjacent cell satisfies a predetermined condition while a predetermined timer is activated, a measurement result in measurement unit 102 is transmitted to radio base station eNB. The determination unit 10 configured to determine that notification should be made And a measurement report transmission unit configured to transmit the measurement result to the radio base station eNB when the determination unit 106 determines that the measurement result should be notified to the radio base station eNB. The determination unit 106 is configured to change the Measurement Reference CC and reset the predetermined timer when the CC satisfying the selection condition is changed while the predetermined timer is activated. Is the gist.

  In the first to third features of the present embodiment, the Measurement Reference CC selection unit 104 may be configured to select the CC with the best radio quality as the CC that satisfies the selection condition.

  Alternatively, in the first to third features of the present embodiment, the Measurement Reference CC selection unit 104 may be configured to select the CC with the lowest radio quality as the CC that satisfies the selection condition.

  In the first to third features of the present embodiment, the determination unit 106 determines that the radio quality of the neighboring cell is higher than the radio quality of the neighboring cell by a predetermined offset (event A3). When the quality is better than the first threshold (event A1), when the radio quality of the communicating cell is worse than the second threshold (event A2), the radio quality of the neighboring cell is better than the third threshold. (Event A4), when the wireless quality of the communicating cell is worse than the fourth threshold and the wireless quality of the neighboring cell is better than the fifth threshold (event A5), or the measurement result is a period The wireless quality of the cell in communication or the neighboring cell may be determined to satisfy a predetermined condition in at least one of the cases where the transmission timing is determined when the transmission is performed.

  In the first to third features of the present embodiment, the predetermined timer may be a Time-To-Trigger.

  A fourth feature of the present embodiment is a communication control method in a mobile station UE that can communicate with a radio base station eNB using two or more CCs, and relates to each CC in two or more CCs. A first step of measuring the radio quality of a cell in communication or a neighboring cell, a second step of selecting a CC satisfying a selection condition as a measurement reference CC from two or more CCs, and a cell in communication in a measurement reference CC Or the third step of determining that the radio base station eNB should be notified of the measurement result in the first step when the radio quality of the adjacent cell satisfies a predetermined condition while the predetermined timer is activated. In the third step, it is determined that the measurement result should be notified to the radio base station eNB. A fourth step of transmitting the measurement result to the radio base station eNB, and in the third step, when the CC satisfying the selection condition is changed while the predetermined timer is activated, The gist is to change the Measurement Reference CC and continue to start the predetermined timer.

  The operations of the mobile station UE and the radio base station DeNB described above may be implemented by hardware, may be implemented by a software module executed by a processor, or may be implemented by a combination of both. .

  The software module includes a RAM (Random Access Memory), a flash memory, a ROM (Read Only Memory), an EPROM (Erasable Programmable ROM), an EEPROM (Electronically Erasable and Programmable ROM, a hard disk, a registerable ROM, a hard disk). Alternatively, it may be provided in a storage medium of an arbitrary format such as a CD-ROM.

  Such a storage medium is connected to the processor so that the processor can read and write information from and to the storage medium. Further, such a storage medium may be integrated in the processor. Such a storage medium and processor may be provided in the ASIC. Such an ASIC may be provided in the mobile station UE or the radio base station DeNB. Further, the storage medium and the processor may be provided as a discrete component in the mobile station UE or the radio base station DeNB.

  Although the present invention has been described in detail using the above-described embodiments, it is obvious to those skilled in the art that the present invention is not limited to the embodiments described in this specification. The present invention can be implemented as modified and changed modes without departing from the spirit and scope of the present invention defined by the description of the scope of claims. Therefore, the description of the present specification is for illustrative purposes and does not have any limiting meaning to the present invention. Therefore, the description of the present specification is for illustrative purposes and does not have any limiting meaning to the present invention.

UE ... mobile station 102 ... measurement unit 104 ... Measurement Reference CC selection unit 106 ... determination unit 108 ... Measurement Report transmission unit 110 ... Measurement control signal reception unit

Claims (7)

A mobile station capable of communicating with a radio base station using two or more carriers,
A measurement unit configured to measure radio quality of a cell in communication or an adjacent cell for each of the two or more carriers; and
A reference carrier selection unit configured to select a carrier that satisfies a selection condition from the two or more carriers as a reference carrier for measurement;
When the radio quality of the cell in communication or the neighboring cell in the measurement reference carrier satisfies a predetermined condition while a predetermined timer is activated, the measurement result in the measurement unit is notified to the radio base station A determiner configured to determine that it should be,
A transmitter configured to transmit the measurement result to the radio base station when the determination unit determines that the measurement result should be notified to the radio base station;
The determination unit is configured not to change the reference carrier for measurement even when a carrier satisfying the selection condition is changed while the predetermined timer is activated. Mobile station. A mobile station capable of communicating with a radio base station using two or more carriers,
A measurement unit configured to measure radio quality of a cell in communication or an adjacent cell for each of the two or more carriers; and
A reference carrier selection unit configured to select a carrier that satisfies a selection condition from the two or more carriers as a reference carrier for measurement;
When the radio quality of the cell in communication or the neighboring cell in the measurement reference carrier satisfies a predetermined condition while a predetermined timer is activated, the measurement result in the measurement unit is notified to the radio base station A determiner configured to determine that it should be,
A transmitter configured to transmit the measurement result to the radio base station when the determination unit determines that the measurement result should be notified to the radio base station;
The determination unit changes the reference carrier for measurement when the carrier satisfying the selection condition is changed while the predetermined timer is activated, and continues the activation of the predetermined timer. A mobile station characterized in that the mobile station is configured as follows. A mobile station capable of communicating with a radio base station using two or more carriers,
A measurement unit configured to measure radio quality of a cell in communication or an adjacent cell for each of the two or more carriers; and
A reference carrier selection unit configured to select a carrier that satisfies a selection condition from the two or more carriers as a reference carrier for measurement;
When the radio quality of the cell in communication or the neighboring cell in the measurement reference carrier satisfies a predetermined condition while a predetermined timer is activated, the measurement result in the measurement unit is notified to the radio base station A determiner configured to determine that it should be,
A transmitter configured to transmit the measurement result to the radio base station when the determination unit determines that the measurement result should be notified to the radio base station;
The determination unit is configured to change the reference carrier for measurement and reset the predetermined timer when a carrier that satisfies the selection condition is changed while the predetermined timer is activated. A mobile station characterized by that.   The mobile station according to any one of claims 1 to 3, wherein the reference carrier selection unit is configured to select a carrier having the best radio quality as a carrier that satisfies the selection condition. . The determination unit
When the radio quality of the neighboring cell is better than the radio quality of the cell in communication by a predetermined offset,
When the wireless quality of the communicating cell is better than the first threshold,
If the wireless quality of the communicating cell is worse than the second threshold,
When the wireless quality of the neighboring cell becomes better than a third threshold,
When the radio quality of the cell in communication is worse than a fourth threshold and the radio quality of the neighboring cell is better than a fifth threshold, or
In at least one case where the measurement result is a transmission timing when periodically transmitted,
The mobile station according to any one of claims 1 to 4, wherein the mobile station is configured to determine that a radio quality of the cell in communication or an adjacent cell satisfies the predetermined condition.   The mobile station according to claim 1, wherein the predetermined timer is a Time-To-Trigger. A communication control method in a mobile station capable of communicating with a radio base station using two or more carriers,
Measuring a radio quality of a cell in communication or a neighboring cell for each of the two or more carriers;
A second step of selecting, from the two or more carriers, a carrier that satisfies a selection condition as a reference carrier for measurement;
When the radio quality of the cell in communication or the neighboring cell on the measurement reference carrier satisfies a predetermined condition while a predetermined timer is activated, the measurement result in the first step is notified to the radio base station A third step of determining that it should be
A fourth step of transmitting the measurement result to the radio base station when it is determined in the third step that the measurement result should be notified to the radio base station;
In the third step, when the carrier satisfying the selection condition is changed while the predetermined timer is activated, the measurement reference carrier is changed and the activation of the predetermined timer is continued. A communication control method characterized by the above.

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