JP2014049933A - Base station, and wireless communication system and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide techniques for timely deletion of secondary cell allocation.SOLUTION: A base station 100 comprises: signal transmitting/receiving units 110 and 120 that communicate radio signals with a user device; a cell management unit 130 that manages a primary cell and one or more secondary cells to be allocated to the user device for radio signal communication; and a timer management unit 140 that manages a timer for managing the state of a secondary cell allocated to the user device. When the cell management unit 130 allocates a secondary cell to the user device, the time management unit 140 starts a timer for the allocated secondary cell. The timer management unit 140 resets and restarts the timer when radio resources for the secondary cell are scheduled. The cell management unit 130 deletes the secondary cell allocation from the user device when the timer exceeds a predetermined threshold.

Description

  The present invention relates to wireless communication technology, and more particularly to wireless communication using carrier aggregation.

  Currently, 3GPP (3rd Generation Partnership Project) is promoting standardization of LTE-A (Long Term Evolution-Advanced) as the next generation communication standard of LTE (Long Term Evolution). In the LTE-A system, a carrier aggregation (CA) technique is introduced in order to realize a throughput that exceeds the LTE system while ensuring backward compatibility with the LTE system. In carrier aggregation technology, an LTE carrier (also referred to as a component carrier) having a maximum bandwidth of 20 MHz supported by the LTE system is used as a basic component, and by using these multiple component carriers at the same time, wider bandwidth communication is possible. It is intended to be realized.

  In the carrier aggregation, for example, an arrangement of component carriers as shown in FIG. 1 is assumed. In Case 1, two adjacent 20 MHz bands can be used as a 40 MHz band by carrier aggregation. Case 1 is effectively used in a case where a continuous band larger than 20 MHz can be secured, and can achieve a throughput higher than that of the LTE system while ensuring backward compatibility with the LTE system. In case 2, two 10 MHz bands separated from each other can be used as a 20 MHz band by carrier aggregation. Case 2 is effectively used when the frequency band allocation to the operator is fragmented, and can achieve a throughput higher than that of the LTE system while ensuring backward compatibility with the LTE system. .

  In carrier aggregation, a user apparatus (User Equipment: UE) can communicate with a base station (evolved NodeB: eNB) using a plurality of component carriers simultaneously. In carrier aggregation, a highly reliable primary cell (Primary Cell: Pcell) that ensures connectivity with user equipment and a secondary cell (Secondary Cell: Scell) that is additionally set in the user equipment connected to the primary cell And are set. For example, in the specific example shown in FIG. 1, one of the two component carriers may be set as a primary cell and the other may be set as a secondary cell.

  The primary cell is a cell similar to the LTE system, and is a cell for ensuring connectivity between the user apparatus and the network. That is, in a primary cell, a user apparatus receives PDCCH (Physical Downlink Control Channel) and PDSCH (Physical Downlink Shared Channel Control), and PUCCH (Physical Uplink Control, PUCCH (Physical Uplink Control). (Channel) can be transmitted. Moreover, when changing a primary cell, the user apparatus needs to perform a handover.

  On the other hand, the secondary cell is a cell that is added to the primary cell and set in the user apparatus. The addition and the deletion of the secondary cell are executed by RRC (Radio Resource Control) configuration (Configuration). In the secondary cell, the user apparatus does not transmit PUCCH and PRACH. In addition, immediately after the secondary cell is set in the user apparatus, it is in an inactive state, and communication or scheduling is possible only after activation in the MAC layer.

3GPP TS 36.300 V10.7.0 (2012-03)

  In the carrier aggregation currently considered, when a secondary cell is added to the user apparatus, the user apparatus continues to hold the assigned secondary cell until RRC signaling for deleting the secondary cell is notified from the base station. . For this reason, when the user apparatus stops using the assigned secondary cell, it is undesirable for the user apparatus to keep the secondary cell from the viewpoint of efficient use of radio resources and battery saving of the user apparatus. Therefore, a mechanism for deleting secondary cells that are not used for a certain period is required.

  Further, in the LTE system and the LTE-A system, discontinuous reception (DRX) control is adopted in order to save the battery of the user apparatus. In the DRX control, even when the user apparatus establishes an RRC connection with the base station (RRC connected state), for example, transmission / reception processing of the user apparatus is omitted according to increase / decrease in the amount of transmission / reception data. In the carrier aggregation currently considered, when the secondary cell allocated to the user apparatus in the DRX state is deleted, when the RRC signaling for deleting the secondary cell is received from the base station, the user apparatus enters the non-DRX state. The secondary cell deletion process is executed again, and the non-DRX state is continued even after the process is completed. Therefore, when deleting a secondary cell from a user apparatus in the DRX state, a mechanism is required for the user apparatus to quickly transition to the DRX state after the completion of the secondary cell deletion process.

  In view of the above problems, an object of the present invention is to provide a technique for deleting a secondary cell in a timely manner.

  In order to solve the above problems, an aspect of the present invention includes a signal transmission / reception unit that communicates a radio signal with a user apparatus, a primary cell that is allocated to the user apparatus to communicate the radio signal, and one or more secondary cells. A base station having a cell management unit for managing and a timer management unit for managing a timer for managing a state of a secondary cell assigned to the user apparatus, wherein the cell management unit provides a secondary cell to the user apparatus. The timer management unit starts the timer for the allocated secondary cell, and when the radio resource of the secondary cell is scheduled to the user apparatus, the timer management unit When the timer is reset and restarted and the timer exceeds a predetermined threshold, the cell management unit A base station to remove the secondary cell from.

  According to the present invention, it is possible to delete a secondary cell in a timely manner.

FIG. 1 is a diagram schematically illustrating carrier aggregation. FIG. 2 is a diagram schematically illustrating control by the Scell Inactive Timer according to an embodiment of the present invention. FIG. 3 is a diagram schematically illustrating a wireless communication system according to an embodiment of the present invention. FIG. 4 is a block diagram illustrating a configuration of a base station according to an embodiment of the present invention. FIG. 5 is a flowchart illustrating the operation of the Scell Inactive Timer according to an embodiment of the present invention. FIG. 6 is a diagram schematically illustrating an operation of a Scell Inactive Timer in a DRX state according to another embodiment of the present invention. FIG. 7 is a block diagram illustrating a configuration of a base station according to another embodiment of the present invention. FIG. 8 is a flowchart illustrating an operation of a Scell Inactive Timer according to another embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  In the embodiments disclosed below, a wireless communication system capable of using carrier aggregation is described. In carrier aggregation, a base station (evolved NodeB: eNB) is added as necessary after a primary cell for maintaining a communication connection with a user equipment (User Equipment: UE) and a connection to the primary cell by the user equipment. Secondary cell. According to an embodiment to be described later, in order to avoid the secondary cell allocated to the user apparatus being kept without being used, the base station manages the Scell Inactive Timer that manages the secondary cell (Scell). Use to manage the state of the secondary cell assigned to the user equipment. By using this Scell Inactive Timer, the base station quickly collects secondary cells that are no longer needed after allocation to the user apparatus.

  More specifically, as illustrated in FIG. 2, when the base station allocates a secondary cell to the user apparatus, the base station activates a Scell Inactive Timer. The activation timing may be a message transmission timing for adding the secondary cell, a complete reception timing for a message for adding the secondary cell, or a timing for activating the secondary cell for the first time after adding the secondary cell. Good. Each time a new radio resource is allocated to the secondary cell to the user apparatus, the base station determines that the secondary cell is being used, resets the Scell Inactive Timer, and restarts. On the other hand, when the Scell Inactive Timer exceeds a predetermined threshold, the base station determines that the assigned secondary cell is no longer necessary, and deletes the secondary cell from the user apparatus. Further, when a predetermined threshold is exceeded, the base station may reset and restart the Scell Inactive Timer.

  In this way, by using the Scell Inactive Timer, it becomes possible to collect unnecessary secondary cells from the user equipment in a timely manner, and the user equipment keeps the secondary cells that are no longer needed. It is possible to reduce the inefficient utilization of the generated radio resources and the waste of the battery of the user equipment.

  First, a radio communication system according to an embodiment of the present invention will be described with reference to FIG. FIG. 3 is a diagram schematically illustrating a wireless communication system according to an embodiment of the present invention.

  As illustrated in FIG. 3, the wireless communication system 10 is a wireless communication system that implements wireless communication using carrier aggregation, such as an LTE-A (Long Term Evolution Advanced) system. The radio communication system 10 includes a base station (eNB) 100 and one or more user apparatuses (UE) 200. Typically, the user apparatus 200 may be any appropriate user apparatus having a wireless communication function such as a mobile phone or a smartphone as illustrated.

  The base station 100 wirelessly connects to the user apparatus 200, thereby transmitting downlink (DL) data received from a communication-connected upper station or server (not shown) to the user apparatus 200 and from the user apparatus 200. The received uplink (UL) data is transmitted to an upper station (not shown). In a typical hardware configuration, the base station 100 has a CPU (Central Processing Unit) such as a processor, a memory device such as a RAM (Random Access Memory), an auxiliary storage device such as a hard disk device, and a communication for communicating radio signals. It comprises an interface device for exchanging various data and / or instructions with a device, a host station, an external server, an operator, and the like. Each function of the base station 100 to be described later loads data and programs stored in the auxiliary storage device to the memory device via the communication device and / or the interface device, and the CPU processes the data according to the loaded program. It is realized by.

  Next, a configuration of a base station according to an embodiment of the present invention will be described with reference to FIG. FIG. 4 is a block diagram illustrating a configuration of a base station according to an embodiment of the present invention.

  As illustrated in FIG. 4, the base station 100 includes a DL signal transmission unit 110, a UL signal reception unit 120, a cell management unit 130, and a Scell Inactive Timer management unit 140.

  The DL signal transmission unit 110 transmits a radio signal including a data signal and / or a control signal to the user apparatus 200 via the primary cell and / or the secondary cell. For example, the DL signal transmission unit 110 converts data provided from the server in response to a request from the user apparatus 200 into a radio signal and transmits the radio signal to the requesting user apparatus 200. Also, the DL signal transmission unit 110 converts control information such as scheduling information and various signaling necessary for wireless communication with the user apparatus 200 into a radio signal, and transmits the radio signal to the user apparatus 200.

  The UL signal reception unit 120 receives a radio signal including a data signal and / or a control signal from the user apparatus 200 via the primary cell and / or the secondary cell. For example, when the user apparatus 200 transmits a data signal using radio resources of the assigned primary cell and / or secondary cell, the UL signal reception unit 120 transfers the received data signal to a transmission destination server. In addition, when the user apparatus 200 transmits a control signal using radio resources of the assigned primary cell and / or secondary cell, the UL signal reception unit 120 uses the received control signal for subsequent communication, and / Or forward to higher station.

  The cell management unit 130 manages a primary cell and one or more secondary cells that the base station 100 can provide. The primary cell (Primary Cell: Pcell) is a highly reliable cell that secures connectivity with the user apparatus 200, and the user apparatus 200 needs to perform handover when changing the primary cell. A secondary cell (Secondary Cell: Scell) is a cell that is added to the primary cell and set in the user apparatus 200. The addition and deletion of the secondary cell is performed by RRC configuration. The secondary cell is in an inactive state immediately after being set in the user apparatus 200 by the RRC configuration. Accordingly, the secondary cell set in the user apparatus 200 becomes communicable, that is, can be scheduled only after being activated in the MAC layer.

  When the user apparatus 200 is communicatively connected to the base station 100, the cell management unit 130 connects to the user apparatus 200 through the primary cell. When a secondary cell needs to be added for some reason after connecting to the primary cell, the cell management unit 130 assigns the secondary cell to the user apparatus 200. Specifically, when the cell management unit 130 determines to allocate a secondary cell to the user apparatus 200, the cell management unit 130 instructs the DL signal transmission unit 110 to transmit RRC signaling notifying that the secondary cell is allocated to the user apparatus 200. .

  In addition, after the secondary cell is allocated, as described later, when the Scell Inactive Timer management unit 140 notifies that the Scell Inactive Timer exceeds a predetermined threshold, the cell management unit 130 allocates to the user apparatus 200. In order to recover the secondary cell, the DL signal transmission unit 110 is instructed to transmit RRC signaling for deallocating the secondary cell. When receiving this RRC signaling, the user apparatus 200 starts a secondary cell deletion process. At this time, the Scell Inactive Timer manager 140 may reset the Scell Inactive Timer and restart it.

  The Scell Inactive Timer management unit 140 manages a Scell Inactive Timer for managing a secondary cell assigned to the user apparatus 200. The Scell Inactive Timer is set for the secondary cell allocated to the user apparatus 200, and the period during which the radio resource of the secondary cell is not allocated to the user apparatus 200, that is, the period during which the user apparatus 200 does not use the secondary cell. Used to keep time. When the Scell Inactive Timer exceeds a predetermined period, the Scell Inactive Timer management unit 140 notifies the cell management unit 130 that the secondary cell is not used, and causes the cell management unit 130 to collect the secondary cell.

  Specifically, when the cell management unit 130 allocates a secondary cell to the user apparatus 200, the Scell Inactive Timer management unit 140 activates the Scell Inactive Timer for the secondary cell allocated to the user apparatus 200. When the secondary cell is taken over before and after the handover, the Scell Inactive Timer management unit 140 takes over the value of the Scell Inactive Timer and continues timing.

  After the activation of the Scell Inactive Timer, every time the radio resource of the secondary cell is allocated to the user apparatus 200, the Scell Inactive Timer management unit 140 determines that the secondary cell is used by the user apparatus 200, and the Scell Inactive Timer Reset and restart.

When the Scell Inactive Timer exceeds a predetermined threshold, the Scell Inactive Timer management unit 140 determines that the secondary cell is no longer necessary for the user apparatus 200 and notifies the cell management unit 130 that the secondary cell is not used. To do. When receiving the notification, the cell management unit 130 deletes the secondary cell from the user apparatus 200. At this time, the Scell Inactive Timer manager 140 may reset the Scell Inactive Timer and restart it.

Next, the operation of the Scell Inactive Timer according to an embodiment of the present invention will be described with reference to FIG. FIG. 5 is a flowchart illustrating the operation of the Scell Inactive Timer according to an embodiment of the present invention.

  As shown in FIG. 5, in response to the cell management unit 130 assigning a secondary cell to the user apparatus 200, the Scell Inactive Timer management unit 140 activates the Scell Inactive Timer in step S101.

  In step S102, the cell management unit 130 detects whether the radio resource of the allocated secondary cell is scheduled for the user apparatus 200. For example, when the cell management unit 130 is notified by the scheduling unit (not shown) or the like that the radio resource of the secondary cell is allocated to the user apparatus 200, the radio resource of the allocated secondary cell is transmitted to the user apparatus 200. It can be determined that the schedule has been scheduled.

  When the cell management unit 130 detects that the radio resource of the secondary cell is allocated to the user apparatus 200 (S102: Y), the cell management unit 130 allocates the radio resource of the secondary cell to the user apparatus 200. This is notified to the Scell Inactive Timer management unit 140, the process returns to Step S101, and the Scell Inactive Timer management unit 140 resets and restarts the Scell Inactive Timer management unit 140.

  On the other hand, when the cell management unit 130 does not detect that the radio resource of the secondary cell is allocated to the user apparatus 200 (S102: N), the Scell Inactive Timer management unit 140 counts the Scell Inactive Timer activated in Step S101. The process proceeds to step S103. That is, the Scell Inactive Timer management unit 140 continues to count the Scell Inactive Timer until notified from the cell management unit 130 that the radio resource of the secondary cell has been allocated to the user apparatus 200.

In step S103, the Scell Inactive Timer management unit 140 determines whether the Scell Inactive Timer exceeds a predetermined threshold. When it is determined that the Scell Inactive Timer has exceeded the predetermined threshold (S103: Y), the Scell Inactive Timer management unit 140 notifies the cell management unit 130 that the secondary cell assigned to the user apparatus 200 is no longer used. To do. At this time, the Scell Inactive Timer manager 140 may reset the Scell Inactive Timer and restart it.
On the other hand, when the Scell Inactive Timer is equal to or less than the predetermined threshold (S103: N), the Scell Inactive Timer management unit 140 continues counting the Scell Inactive Timer, and the process returns to Step S102.

  That is, the Scell Inactive Timer management unit 140 is notified until the cell management unit 130 notifies that the radio resource of the secondary cell is allocated to the user apparatus 200 or until the Scell Inactive Timer exceeds a predetermined threshold. Continue to count the Inactive Timer.

  In step S104, when notified from the Scell Inactive Timer management unit 140 that the secondary cell is no longer used, the cell management unit 130 deletes the secondary cell from the user apparatus 200 in step S104, and the Scell Inactive Timer. Ends the operation.

  Next, an embodiment in which discontinuous reception (DRX) control is used will be described with reference to FIG. In the present embodiment, the operation of the Cell Inactive Timer when the wireless communication system 10 adopts intermittent reception control for battery saving of the user apparatus 200 will be described.

  In the DRX control, the base station 100 manages the user device 200 connected to the base station 100, such as the user device 200 in the RRC connected state, in two states, an active state and an inactive state. While the user apparatus 200 is set in an active state (a state in which DRX is disabled, that is, a non-DRX state), the user apparatus 200 monitors a downlink control channel such as PDCCH and feeds back to the base station 100. Report information. Examples of the feedback information include CQI (Channel Quality Indicator), PMI (Precoding Matrix Index), RI (Rank Indicator), and PTI (Precoding Type Indicator). On the other hand, when the user apparatus 200 is set to an inactive state (a state in which DRX is enabled, that is, a DRX state), the user apparatus 200 does not monitor a downlink control channel such as PDCCH, and feedback information Do not report. Thereby, the battery saving of the user apparatus 200 can be aimed at.

  For example, in the LTE system or the LTE-A system, the active state is 1) if any of the On Duration Timer, drx-Inactivity Timer, drx-Retransmission Timer, or mac-contention Resolution Timer is activated. When a scheduling request is transmitted, 3) When a UL Grant for UL HARQ retransmission is allocated to the UE, 4) When the UE receives a Random Access Response and does not receive a PDCCH instructing new transmission after that, The UE is defined to be in the active state when any of the following cases is true. On the other hand, in all other cases, the UE is defined to be in an inactive state.

  Here, when the user apparatus 200 transitions to the inactive state or the DRX state when the Scell Inactive Timer exceeds a predetermined threshold, the base station 100 transmits a signal for deleting the secondary cell to the user apparatus 200 By doing so, the user apparatus 200 is transitioned to an active state or a non-DRX state, which is not desirable from the viewpoint of battery saving. Therefore, in the present embodiment, as illustrated in FIG. 6, the user apparatus 200 is inactive immediately before the user apparatus 200 is notified of deletion of the secondary cell from the base station 100, such as when the deletion of the secondary cell is determined. When it is in the state, upon receiving a notification that the secondary cell deletion processing is completed from the user apparatus 200, the base station 100 forces the user apparatus 200 to transmit a control signal such as DRX MAC CE to the user apparatus 200. Inactive. Thereby, the user apparatus 200 can be changed to the active state only during the execution of the secondary cell deletion process, and can be quickly returned to the inactive state after the process is completed, thereby enabling effective battery saving.

  Next, a configuration of a base station according to another embodiment of the present invention will be described with reference to FIG. FIG. 7 is a block diagram illustrating a configuration of a base station according to another embodiment of the present invention.

  As illustrated in FIG. 7, the base station 100 includes a DL signal transmission unit 110, a UL signal reception unit 120, a cell management unit 130, a Scell Inactive Timer management unit 140, and a DRX state management unit 150. The DL signal transmission unit 110, the UL signal reception unit 120, the cell management unit 130, and the Scell Inactive Timer management unit 140 are the same as those illustrated in FIG.

  The DRX state management unit 150 manages whether or not the user apparatus 200 that is in communication connection with the base station 100 (that is, RRC connected) is in an intermittent reception state. When the cell management unit 130 deletes the secondary cell assigned to the user apparatus 200, the DRX state management unit 150 checks whether the user apparatus 200 is in the inactive state or the DRX state immediately before the deletion of the secondary cell. For example, when the Scell Inactive Timer management unit 140 determines that the Scell Inactive Timer exceeds the threshold, the Scell Inactive Timer management unit 140 instructs the cell management unit 140 to delete the secondary cell, and the DRX state management unit 150 deletes the secondary cell. You may notify that. In response to receiving this notification, the DRX state management unit 140 may confirm whether the user apparatus 200 is in an active state or an inactive state. When the user apparatus 200 is in the inactive state or the DRX state, the DRX state management unit 150 sends a DRX state transition signal to the user apparatus 200 in order to cause the DL signal transmission unit 110 to shift the user apparatus to the active state or the non-DRX state. Instruct to send. For example, in the LTE system or LTE-A system, the DRX state management unit 150 transmits a DRX MAC CE (Discontinuous Reception Medium Control Control Element) to the user apparatus 200 when the secondary cell deletion procedure is completed. The user apparatus 200 is forcibly changed to the inactive state or the DRX state. Thereby, in response to reception of the signal for deleting the secondary cell, the user apparatus 200 quickly transitions from the inactive state or the DRX state to the active state or the non-DRX state, and then quickly enters the inactive state or the DRX state. It becomes possible to return.

  Next, referring to FIG. 8, the operation of the Scell Inactive Timer according to another embodiment of the present invention will be described. FIG. 8 is a flowchart illustrating an operation of a Scell Inactive Timer according to another embodiment of the present invention.

  As shown in FIG. 8, steps S201 to S204 are the same as steps S101 to S104 in FIG.

  When the cell management unit 130 determines to delete the secondary cell assigned to the user apparatus 200 in step S204 and transmits a signal for deleting the secondary cell to the user apparatus 200 via the DL signal transmission unit 110, the step In S205, the DRX state management unit 150 confirms whether the user apparatus 200 is in the DRX state or the non-DRX state when the cell management unit 130 determines to delete the secondary cell.

  When the user apparatus 200 is in the inactive state or the DRX state (S205: Y), the DRX state management unit 150 quickly determines the user apparatus 200 that has transitioned to the active state or the non-DRX state after the secondary cell deletion or Force return to DRX state. For this reason, when receiving the notification that the secondary cell deletion process is completed from the user apparatus 200, the DRX state management unit 150 instructs the DL signal transmission unit 110 to transmit a DRX state transition signal such as DRX MAC CE. On the other hand, when the user apparatus 200 is not in the inactive state or the DRX state (S205: N), the DRX state management unit 150 determines that the user apparatus 200 should maintain the active state or the non-DRX state, and shifts to the DRX state. The process ends without transmitting a signal.

  As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to the specific embodiment mentioned above, In the range of the summary of this invention described in the claim, various deformation | transformation・ Change is possible.

DESCRIPTION OF SYMBOLS 10 Radio | wireless communications system 100 Base station 110 DL signal transmission part 120 UL signal receiving part 130 Cell management part 140 Scell Inactive Timer management part 150 DRX state management part 200 User apparatus

Claims (6)

A signal transmission / reception unit for communicating a radio signal with the user apparatus;
A cell management unit for managing a primary cell and one or more secondary cells allocated to the user apparatus for communicating the radio signal;
A timer management unit for managing a timer for managing the state of the secondary cell assigned to the user apparatus;
A base station having
When the cell management unit assigns a secondary cell to the user device, the timer management unit starts the timer for the assigned secondary cell,
When radio resources of the secondary cell are scheduled in the user equipment, the timer management unit resets and restarts the timer,
When the timer exceeds a predetermined threshold, the cell management unit is a base station that deletes the secondary cell from the user apparatus. It further has an intermittent reception state management unit for managing the intermittent reception state of the user equipment that is connected to communicate with the base station,
When the cell management unit deletes the secondary cell from the user apparatus, the intermittent reception state management unit confirms whether the user apparatus is in an intermittent reception state immediately before the deletion of the secondary cell, and the user apparatus performs intermittent reception. The base station according to claim 1, wherein, when the state is a state, the user apparatus is transitioned to an intermittent reception state after the secondary cell is deleted.   The intermittent reception state management unit confirms whether or not the user apparatus is in an intermittent reception state in response to receiving a notification from the timer management unit that the timer has exceeded a predetermined threshold. Item 3. The base station according to Item 2. The base station communicates with the user equipment using carrier aggregation;
The primary cell is a cell for maintaining a communication connection with the user equipment,
The base station according to claim 1, wherein the secondary cell is a cell assigned in addition to the primary cell. A user device;
A base station in communication connection with the user equipment;
A wireless communication system comprising:
The base station
A signal transmission / reception unit for communicating a radio signal with the user device;
A cell management unit for managing a primary cell and one or more secondary cells allocated to the user apparatus for communicating the radio signal;
A timer management unit for managing a timer for managing the state of the secondary cell assigned to the user apparatus;
Have
When the cell management unit assigns a secondary cell to the user device, the timer management unit starts the timer for the assigned secondary cell,
When radio resources of the secondary cell are scheduled in the user equipment, the timer management unit resets and restarts the timer,
When the timer exceeds a predetermined threshold, the cell management unit deletes the secondary cell from the user apparatus. A method in a base station for communication connection with a user apparatus via a primary cell and one or more secondary cells,
Allocating a secondary cell to the user equipment, starting a timer for the allocated secondary cell;
Resetting and restarting the timer when radio resources of the secondary cell are scheduled in the user equipment;
Deleting the secondary cell when the timer exceeds a predetermined threshold; and
Having a method.

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