JP2014187426A - Base station and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a re-transmission control technique to dissolve discrepancy in the active state of a secondary cell between a network side and a user side in carrer aggregation in a radio communication system.SOLUTION: A base station 100 includes: a signal transmitting/receiving unit 110 for communicating radio signals with a user device; a cell management unit 120 for managing a primary cell and a secondary cell allocated to the user device; and a re-transmission control unit 130 for controlling re-transmission of an activation instruction or a deactivation instruction of the secondary cell. During a period when the re-transmission control unit 130 does not satisfy a prescribed end condition, whenever re-transmission of the activation instruction or the deactivation instruction exceeds a limit, the base station 100 instructs the signal transmitting/receiving unit 110 to re-generate the activation instruction or the deactivation instruction. Once the prescribed end condition is satisfied, the base station 100 instructs the signal transmitting/receiving unit 110 to stop re-generating the activation instruction or the deactivation instruction.

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 the standardization of LTE-Advanced as the next generation communication standard of LTE (Long Term Evolution). In the LTE-Advanced system, carrier aggregation (CA) technology is introduced in order to achieve a throughput higher than that of 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 when it is activated in the MAC (Medium Access Control) layer. For this reason, in order to make the set secondary cell in a communicable state, that is, in a schedulable state, it is necessary to change the secondary cell to the active state.

  In the LTE-Advanced system currently under consideration, in order to transition the secondary cell to the active state and the inactive state, as shown in FIG. 2, the base station sends a MAC CE (Control Element) to the user equipment in the MAC layer. By transmitting, the user apparatus is instructed to activate / deactivate the set secondary. When receiving the explicit state transition instruction, the user apparatus transitions the secondary cell to the instructed state.

  Further, when receiving the MAC CE for activating the secondary cell from the base station, the user apparatus activates the secondary cell and activates the SCell Deactivation Timer for the secondary cell. On the other hand, the base station also activates an SCell Deactivation Timer for the secondary cell when receiving an acknowledgment delivery acknowledgment (ACK) for the MAC CE from the user apparatus. That is, a base station and a user apparatus hold | maintain each SCell Deactivation Timer, and manage the state of the said activated secondary cell. After the SCell Deactivation Timer is activated, when the base station schedules a new radio resource to the user apparatus in the secondary cell, the base station and the user apparatus reset their SCell Deactivation Timer and restart. After that, when the SCell Deactivation Timer exceeds a predetermined threshold value or receives an explicit state transition instruction for deactivating the secondary cell from the base station, the user apparatus sets the secondary cell to the inactive state. Transition. When the base station also receives notification from the user apparatus that the secondary cell has been deactivated, the base station determines that the secondary cell has been deactivated and stops scheduling radio resources to the user apparatus in the secondary cell. In this way, it is possible to match the active state / inactive state of the secondary cell between the base station and the user apparatus.

3GPP TS 36.321 V11.1.0 (2012-12) 3GPP TS 36.331 V11.2.0 (2012-12)

  However, when a secondary cell activation command (SCell Activation) or a deactivation command (SCell Deactivation) by MAC CE is performed, there is a possibility that a state mismatch of the secondary cell may occur between the network side and the user equipment.

  Such a state mismatch of the secondary cell between the network side and the user apparatus occurs, for example, under the situation shown in FIG. In the specific example illustrated in FIG. 3, the base station transmits a MAC CE activation command to the user apparatus in order to activate the secondary cell set in the user apparatus. Here, the base station applies retransmission control such as ARQ (Automatic Repeat reQuest) and HARQ (Hybrid ARQ), and is active until receiving acknowledgment (ACK) from the user apparatus. Continue to resend the command. If reception of the activation command fails, the user equipment transmits a non-acknowledgement (NACK) acknowledgment to the base station, and the base station recognizes that the user equipment is still in an inactive state. To do. In this case, the state of the secondary cell recognized between the base station and the user apparatus matches in the inactive state.

  After that, the user apparatus activated the secondary cell in response to the successful reception of the MAC CE and returned the ACK to the base station, but the base station received the NACK by mistake due to the influence of noise or the like. (ACK-> NACK error). In this case, while the user apparatus recognizes that the secondary cell is in an active state, the base station still misidentifies that the secondary cell is in an inactive state. A cell active state mismatch occurs. In this case, although the radio resource is not allocated from the base station, the user apparatus waits for the allocation of the radio resource and consumes unnecessary battery power.

  On the other hand, since retransmission control such as ARQ and HARQ is applied, the base station that misrecognized that the NACK has been received retransmits the activation command, and the state mismatch that has occurred in error is resolved thereafter. However, if the retransmission control has reached a predetermined maximum number of retransmissions when an ACK-> NACK error occurs, the base station will no longer retransmit the activation command and the state mismatch will persist.

  In view of the above problems, an object of the present invention is to solve the inconsistency of the active state of the secondary cell in the carrier aggregation between the network side and the user apparatus in the wireless communication system to which the retransmission control is applied. Is to provide.

  In order to solve the above problems, an aspect of the present invention provides a signal transmission / reception unit that communicates a radio signal with a user apparatus, and a cell that manages a primary cell and a secondary cell that are allocated to the user apparatus for communicating the radio signal. A retransmission control unit that manages a retransmission control unit for controlling retransmission of an activation command for activating the secondary cell and / or a deactivation command for deactivating the secondary cell; Each time the retransmission control means does not satisfy a predetermined termination condition, the control signal instructing the activation command or the deactivation command transmitted by the signal transmitting / receiving unit exceeds the number of retransmissions. In addition, the retransmission control unit regenerates a control signal indicating the activation command or the deactivation command. When the signal transmission / reception unit is instructed and the retransmission control unit satisfies the predetermined termination condition, the retransmission control unit instructs the signal transmission / reception unit to stop the re-instruction of the activation command or the deactivation command. Regarding the base station to instruct

  According to the present invention, in a radio communication system to which retransmission control is applied, it becomes possible to eliminate a mismatch in the active state of secondary cells in carrier aggregation between the network side and a user apparatus.

FIG. 1 is a diagram schematically illustrating carrier aggregation. FIG. 2 is a diagram schematically illustrating an operation example of the SCell Deactivation Timer. FIG. 3 is a schematic diagram illustrating a specific example in which a mismatch of active states occurs between a base station and a mobile station. FIG. 4 is a diagram schematically illustrating active state control according to an embodiment of the present invention. FIG. 5 is a diagram schematically illustrating a wireless communication system according to an embodiment of the present invention. FIG. 6 schematically shows a first embodiment of the present invention. FIG. 7 is a diagram schematically showing a first embodiment of the present invention. FIG. 8 is a block diagram illustrating a configuration of a base station according to the first embodiment of the present invention. FIG. 9 is a flowchart showing retransmission processing in the base station according to the first embodiment of the present invention. FIG. 10 schematically shows a second embodiment of the present invention. FIG. 11 is a block diagram showing a configuration of a base station according to the second embodiment of the present invention. FIG. 12 is a flowchart showing retransmission processing in the base station according to the second embodiment of the present invention.

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

  In an embodiment of the present invention to be described later, in a wireless communication system that supports carrier aggregation, a base station activates a secondary cell set in a user apparatus in order to make the secondary cell communicable. An activation command is transmitted to the user device. Further, the base station transmits a deactivation command for deactivating the secondary cell to the user apparatus in order to make the secondary cell set in the user apparatus in a communication disabled state. Further, in response to transmission of a new activation command or deactivation command, the base station controls retransmission control means (Retx-Timer, Retx-Counter) to control retransmission of the transmitted activation command or deactivation command. ). The base station continues to transmit the activation command or the deactivation command each time the transmitted control signal indicating the activation command or the deactivation command exceeds the retransmission until a predetermined termination condition is satisfied. When the predetermined termination condition is satisfied, the base station stops re-instruction of the activation command or the deactivation command.

  That is, as illustrated in FIG. 4, the base station newly transmits a MAC CE activation command to the user apparatus in order to activate the secondary cell set in the user apparatus. The base station applies retransmission control such as ARQ and HARQ, for example, and continues to retransmit the activation command until ACK is received from the user apparatus. When reception of the MAC CE that activates the secondary cell is not successful, the user apparatus transmits a NACK to the base station, and the base station recognizes that the user apparatus is in an inactive state. In this case, the state of the secondary cell recognized between the base station and the user apparatus matches in the inactive state.

  After that, the user apparatus activates the secondary cell with the successful reception of the MAC CE and returns the ACK, but the base station recognizes that the base station has erroneously received the NACK due to the influence of noise or the like (ACK -> NACK error). In this case, while the user apparatus recognizes that the secondary cell is in an active state, the base station still misidentifies that the secondary cell is in an inactive state. A cell active state mismatch occurs. In the present embodiment, when the applied ARQ or HARQ retransmission control has reached a predetermined maximum number of retransmissions, the retransmission control means is activated in response to reception of a NACK or in DTX (Discontinuous Transmission) determination. In response, the base station retries the activation command. The user apparatus that is already in the active state transmits ACK in response to the received activation command. The base station that has received the ACK determines that the user apparatus has activated the secondary cell, and the state mismatch is resolved.

  In one embodiment, the retransmission control means is a retransmission timer (Retx-Timer) having a predetermined period, and the base station is responsive to newly transmitting an activation command or a deactivation command to the user equipment. Start the retransmission timer. In response to the expiration of the predetermined period, i.e. in response to the expiration of the retransmission timer or in response to receipt of an acknowledgment delivery acknowledgment for the activation or deactivation command The base station ends the retry of the activation command or the deactivation command. At this time, the base station may stop the retransmission timer. Further, when the retransmission timer has expired when the MAC CE has exceeded HARQ retransmission, the secondary cell that has been instructed to be activated by the MAC CE (for example, managed for the secondary cell) It may be considered active (eg by activation / reactivation of an inactivity timer).

  In another embodiment, the retransmission control means is a retransmission counter (Retex-Counter) having a predetermined number of times, and the base station is responsive to newly transmitting an activation command or a deactivation command to the user equipment. To start the retransmission counter. After activation, the retransmission counter is incremented each time an activation command or deactivation command exceeds HARQ retransmission and is retried. In response to resending the activation or deactivation instruction a predetermined number of times, i.e. in response to the retransmission counter exceeding a predetermined threshold, or to the activation or deactivation instruction In response to receiving the acknowledgment delivery confirmation, the base station terminates the retry of the activation or deactivation command. At this time, the retransmission counter may be reset. Further, when the retransmission counter exceeds a predetermined threshold at the time when the MAC CE exceeds the HARQ retransmission, for the secondary cell instructing activation by the MAC CE (for example, for the secondary cell) It may be considered active (eg by starting or restarting a managed inactivity timer).

  Preferably, the predetermined period of the retransmission timer is set to a period longer than a period in which retransmission control such as ARQ or HARQ is performed for the maximum number of retransmissions. As a result, the ACK-> NACK error related to the retransmission of the activation command and the deactivation command causes a mismatch in the active state of the secondary cell between the user apparatus and the base station, and the retransmission has reached the maximum number of retransmissions for retransmission control. Even if the control cannot resolve the state mismatch, it is possible to resolve the state mismatch by continuing the trial of the activation command and the deactivation command based on the retransmission control means.

  First, a radio communication system according to an embodiment of the present invention will be described with reference to FIG. FIG. 5 is a diagram schematically illustrating a wireless communication system according to an embodiment of the present invention.

  As illustrated in FIG. 5, the wireless communication system 10 is a wireless communication system that realizes wireless communication using carrier aggregation, such as an LTE-Advanced system. The radio communication system 10 includes a base station (eNB) 100 and one or more user apparatuses (UE) 200. The user apparatus 200 may typically be any appropriate user apparatus having a wireless communication function such as a mobile phone, a smartphone, a tablet, and a mobile router 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).

  As illustrated, the base station 100 is capable of communicating with the user apparatus 200 via a primary cell (PCell) and a secondary cell (SCell) by applying carrier aggregation and simultaneously using a plurality of component carriers. . The primary cell is a highly reliable primary cell that ensures connectivity with the user apparatus 200, and the secondary cell is additionally set in the user apparatus 200 that is connected to the primary cell. In the primary cell, the user apparatus 200 can receive PDCCH and PDSCH and transmit PUCCH, PUSCH, and PRACH. Moreover, when changing a primary cell, the user apparatus 200 needs to perform a hand-over. In addition, addition and deletion of secondary cells are executed by RRC configuration. Immediately after the secondary cell is set in the user apparatus 200, it is in an inactive state, and communication in the secondary cell becomes possible only after being activated in the MAC layer. For this reason, in order to make the set secondary cell in a communicable state, that is, in a schedulable state, it is necessary to change the secondary cell to the active state. In order to transition the secondary cell to the active state and the inactive state, the base station 100 transmits the MAC CE of the activation command / deactivation command to the user apparatus 200 in the MAC layer, and activates / deactivates the set secondary. Instruct the user device 200 to activate. Upon receiving these explicit state transition instructions, the user apparatus 200 transitions the secondary cell to the instructed state.

  In addition, the base station 100 applies retransmission control such as ARQ and HARQ to the transmission of the activation command and the deactivation command for the secondary cell. That is, in retransmission control, when reception is successful (or when activation or deactivation is successful) in response to an activation command or an inactivity command transmitted from the base station 100, the user apparatus 200 If the ACK is returned to the station 100 and the instruction is not successfully received (when activation or deactivation is not successful), the user apparatus 200 returns a NACK to the base station 100. The base station 100 repeats retransmission until an ACK is received from the user apparatus 200. When the number of retransmissions exceeds the set maximum number of retransmissions, base station 100 ends the retransmission.

  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. For example, each function and process of the base station 100 to be described later is performed by loading data and programs stored in the auxiliary storage device into the memory device via the communication device and / or interface device, and the CPU performing data according to the loaded program. It is realized by processing.

  Next, a base station according to the first embodiment of the present invention will be described with reference to FIGS. In the first embodiment, as shown in FIG. 6, the base station 100 uses a retransmission timer (Retx-Timer) having a predetermined period, and is set in the applied retransmission control such as ARQ and HARQ. If the maximum number of retransmissions has been reached and the retransmission timer has not expired, a MAC CE instructing the activation command and the deactivation command is generated again and transmitted to the user apparatus 200. When receiving an acknowledgment delivery acknowledgment (ACK) in response to the activation command or the deactivation command, the base station 100 stops the retransmission timer. On the other hand, as shown in FIG. 7, until the predetermined period elapses or until an ACK is received for the activation command or the deactivation command, the base station 100 receives the activation command or the deactivation command. Continue regeneration. If the retransmission timer has expired when the maximum number of retransmissions for retransmission control is exceeded, the base station 100 gives up retrying the activation command and the deactivation command. Thereby, even if the maximum number of retransmissions is reached, as long as the retransmission timer has not expired, the base station 100 continues to generate the MAC CE that performs the activation command or the deactivation command until ACK is received. As a result, the active state mismatch of the secondary cell between the base station 100 and the user apparatus 200 due to the ACK → NACK error as described above with reference to FIG. 3 can be resolved.

  FIG. 8 is a block diagram illustrating a configuration of a base station according to the first embodiment of the present invention. As illustrated in FIG. 8, the base station 100 includes a signal transmission / reception unit 110, a cell management unit 120, and a retransmission control unit 130. In this embodiment, the retransmission control unit 130 uses a retransmission timer 131 as a retransmission control unit.

  The signal transmission / reception unit 110 communicates radio signals with the user apparatus 200. In the carrier aggregation, the signal transmission / reception unit 110 exchanges a radio signal including a data signal and / or a control signal with the user apparatus 200 via the primary cell and / or the secondary cell. For example, the signal transmission / reception unit 110 converts data provided from the server in response to a request from the user device 200 into a radio signal, and transmits the wireless signal to the requesting user device 200. In addition, the signal transmission / reception unit 110 converts control information such as scheduling information and various signaling necessary for wireless communication with the user apparatus 200 into a wireless signal, and transmits the wireless signal to the user apparatus 200. In addition, when the user apparatus 200 transmits a data signal using radio resources of the assigned primary cell and / or secondary cell, the signal transmission / reception unit 110 transfers the received data signal to a transmission destination server. Further, when the user apparatus 200 transmits a control signal using the radio resources of the assigned primary cell and / or secondary cell, the signal transmission / reception unit 110 uses the received control signal for subsequent communication, and / or Or, transfer to upper station.

  The cell management unit 120 manages a primary cell and a secondary cell that are allocated to the user apparatus 200 in order to communicate radio signals. The primary cell (PCell) is a highly reliable cell that ensures connectivity with the user apparatus 200, and the user apparatus 200 needs to execute a handover when changing the primary cell. The secondary cell (SCell) is a cell that is added to the primary cell and set in the user apparatus 200. Addition and deletion of secondary cells are 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. For this reason, in order to make the set secondary cell in a communicable state, that is, in a schedulable state, it is necessary to change the secondary cell to the active state. In the LTE-Advanced system, in order to transition the secondary cell to the active state and the inactive state, the base station 100 transmits the MAC CE of the activation command and the deactivation command to the user equipment 200 in the MAC layer, respectively. The user apparatus 200 is transitioned to an active state / inactive state.

  Furthermore, when the activation command and the deactivation command are received from the base station 100, the user apparatus 200 activates the secondary cell and activates its own SCell Deactivation Timer. On the other hand, the base station 100 also activates its own SCell Deactivation Timer when receiving acknowledgment acknowledgment (ACK) for the activation command and the deactivation command from the user apparatus 200. That is, the base station 100 and the user apparatus 200 hold their own SCell Deactivation Timer and manage the state of the activated secondary cell. After the SCell Deactivation Timer is activated, when the cell management unit 120 schedules a new radio resource in the user cell 200 in the secondary cell, the cell management unit 120 and the user device 200 reset their SCell Deactivation Timer and restart. . Thereafter, when the SCell Deactivation Timer exceeds a predetermined threshold or an explicit deactivation command for the secondary cell is transmitted to the user apparatus 200, the user apparatus 200 transitions the secondary cell to the inactive state. Then, the cell management unit 120 also recognizes that the secondary cell has been deactivated by receiving an ACK for the deactivation command, and stops scheduling to the user apparatus 200 in the secondary cell.

  The retransmission control unit 130 manages retransmission control means for controlling retransmission of an activation command for activating a secondary cell and / or a deactivation command for deactivating a secondary cell. While the retransmission control means does not satisfy the predetermined termination condition, each time the control signal indicating the activation command or the deactivation command transmitted by the signal transmitting / receiving unit 110 exceeds the retransmission, the retransmission control unit 130 Alternatively, the signal transmission / reception unit 110 is instructed to regenerate the deactivation command. When the retransmission control unit satisfies a predetermined termination condition, the retransmission control unit 130 instructs the signal transmission / reception unit 110 to stop the re-instruction of the activation command or the deactivation command.

  In the first embodiment, the retransmission control means is a retransmission timer 131 having a predetermined period. The retransmission control unit 130 starts a retransmission timer (Retx-Timer) 131 in response to the signal transmission / reception unit 110 newly transmitting an activation command or a deactivation command to the user apparatus 200 (for example, Retx-Timer). = 0). If the ACK is not received from the user apparatus 200 in response to the transmitted activation command or deactivation command after the retransmission timer 131 is activated, the retransmission control unit 130 confirms whether the retransmission timer 131 has expired and performs retransmission. If the timer 131 has not expired, the signal transmission / reception unit 110 is instructed to regenerate a MAC CE that indicates an active command or an inactive command. That is, until the retransmission timer 131 expires, the retransmission control unit 130 continues the retransmission in response to the failure to receive the ACK. Here, the case where the ACK cannot be received from the user apparatus 200 is, for example, a case where a NACK is received from the user apparatus 200 in response to the transmitted activation command or deactivation command, or a predetermined time from the user apparatus 200 This means a case in which neither ACK nor NACK has been received even if the value exceeds.

  On the other hand, in response to the expiration of the retransmission timer after a predetermined period of time has elapsed, or the acknowledgment transmission acknowledgment (ACK) has been received in response to the activation command or the deactivation command transmitted by the signal transmission / reception unit 110 In response to this, the retransmission control unit 130 ends the generation of the MAC CE that instructs the activation command or the deactivation command. That is, the termination condition of the retransmission timer 131 according to the first embodiment is that the retransmission timer 131 has expired after a predetermined period of time and that an ACK has been received for the transmitted activation command or deactivation command. is there.

  As can be understood from the retransmission control described above, the retransmission control unit 130 can respond to the transmission of the activation command and the deactivation command of the secondary cell even when the retransmission control such as ARQ or HARQ is applied. Thus, retransmission control is performed based on the retransmission timer 131. Preferably, the predetermined period of the retransmission timer 131 is set to a period longer than the time taken for the maximum number of retransmissions in retransmission control such as ARQ or HARQ. For transmission of the activation command and / or deactivation command to the user apparatus 200, the retransmission control unit 130 can receive an ACK even if the maximum number of retransmissions set in retransmission control such as ARQ or HARQ is exceeded. If not, the signal transmission / reception unit 110 is instructed to regenerate the MAC CE instructing the activation command or the deactivation command while the retransmission timer 131 does not expire.

  In one Example, the cell management part 120 sets two or more secondary cells to the user apparatus 200, and communicates with the user apparatus 200 using these secondary cells. In this case, in order to activate or deactivate any secondary cell of the plurality of secondary cells, when transmitting an activation command or deactivation command for the secondary cell to the user apparatus 200, the base station 100 transmits The standard specification stipulates that the MAC CE of the activation command or the deactivation command must be transmitted not only to the target secondary cell but also to other secondary cells set in the user apparatus 200. Yes. For example, for secondary cells that are already active among other secondary cells, the cell management unit 120 instructs the signal transmission / reception unit 110 to transmit an activation command to the user apparatus 200 in order to maintain the active state. You may make it do. On the other hand, for secondary cells that are already in an inactive state among other secondary cells, the cell management unit 120 transmits and receives a deactivation command to the user apparatus 200 in order to maintain the inactive state. 110 may be instructed.

  On the other hand, it is necessary to change the active state of one of the other secondary cells while the retransmission timer 131 is activated while the transmission of the activation command or the deactivation command is started to the secondary cell to be transmitted. When the MAC CE being retransmitted exceeds the retransmission, the retransmission control unit 130 reflects the change in the state of the other secondary cell in the next MAC CE and transmits it. Thus, when an activation command or deactivation command different from the previous one is transmitted, the retransmission control unit 130 may restart the activated retransmission timer 131 (Retx-Timer = 0). That is, if the cell management unit 120 changes the active state of another secondary cell while the retransmission control unit 130 controls the retransmission of the activation command or the deactivation command for the secondary cell to be transmitted, the retransmission control is performed. The unit 130 may reset and restart the retransmission timer 131. This makes it possible to reset the period of the retransmission timer 131 in response to the latest transmission of the activation command or the deactivation command.

  FIG. 9 is a flowchart showing retransmission processing in the base station according to the first embodiment of the present invention. The retransmission process is started, for example, when the base station 100 attempts to set the secondary cell set in the user apparatus 200 to a communication enabled state or a communication disabled state.

  As illustrated in FIG. 9, in step S101, the base station 100 transmits an activation command or a deactivation command for activating or deactivating the secondary cell to the user apparatus 200. The activation command and the deactivation command are transmitted as a MAC CE.

  In step S102, the base station 100 starts a retransmission timer 131 having a predetermined period. When retransmission control such as ARQ or HARQ is applied, the predetermined period of the retransmission timer 131 is preferably set to a period longer than the period required for the maximum number of retransmissions in retransmission control such as ARQ or HARQ.

  In step S103, the base station 100 determines whether an acknowledgment delivery confirmation (ACK) has been received from the user apparatus 200 with respect to the transmitted activation command or deactivation command. When ACK is received from the user apparatus 200 (S103: Y), the base station 100 determines that the user apparatus 200 has successfully activated the secondary cell, ends the retransmission timer 131 in step S104, and performs retransmission processing. finish. On the other hand, when no ACK is received from the user apparatus 200, such as when a NACK is received or a response is not received within a predetermined period (S103: N), the base station 100 indicates that the user apparatus 200 Is determined to have failed to be activated, and the process proceeds to step S105.

  In step S105, the base station 100 further determines whether or not the retransmission timer 131 has expired. When the retransmission timer 131 has expired (S105: Y), the base station 100 ends the retransmission timer 131 in step S104 and ends the retransmission process. On the other hand, when the retransmission timer 131 has not expired (S105: N), the base station 100 proceeds to step S106.

  In step S106, the base station 100 regenerates the MAC CE instructing the activation command or the deactivation command, transmits the MAC CE to the user apparatus 200, returns to step S103, and repeats the above steps. When retransmission control such as ARQ or HARQ is applied, the base station 100 continues until the retransmission timer 131 expires or receives an ACK from the user apparatus 200 even if the maximum number of retransmissions for retransmission control is exceeded. Repeat the retransmission.

  Next, a base station according to a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, as shown in FIG. 10, the base station 100 uses a retransmission counter (Retx-Counter) having a predetermined number of times and sets the maximum number of retransmissions set in retransmission control such as ARQ and HARQ. If the retransmission counter has not reached the predetermined number of times, the MAC CE indicating the activation command and the deactivation command is continuously transmitted to the user apparatus 200. That is, the base station 100 starts a retransmission counter in response to newly transmitting an activation command or a deactivation command to the user apparatus 200 (Retx-Counter = 0). As shown in FIG. 10, the base station 100 continues resending the activation command or the deactivation command until a predetermined number of times is reached or an ACK is received for the activation command or the deactivation command. To do. Thus, even if the maximum number of retransmissions is reached, the base station 100 continues to generate the MAC CE that instructs the activation command or the deactivation command until ACK is received. As a result, the active state mismatch of the secondary cell between the base station 100 and the user apparatus 200 due to the ACK → NACK error as described above with reference to FIG. 3 can be resolved. Finally, when the maximum number of retransmissions for retransmission control is exceeded and the retransmission counter reaches a predetermined number, the base station 100 gives up retrying the activation command and the deactivation command.

  FIG. 11 is a block diagram showing a configuration of a base station according to the second embodiment of the present invention. As illustrated in FIG. 11, the base station 100 includes a signal transmission / reception unit 110, a cell management unit 120, and a retransmission control unit 130. In the present embodiment, the retransmission control unit 130 uses a retransmission counter 132 as retransmission control means. Since the signal transmission / reception unit 110 and the cell management unit 120 according to the second embodiment are the same as those of the first embodiment, the overlapping description is omitted.

  In the second embodiment, the retransmission control means is a retransmission counter 132 having a predetermined number of times. The retransmission control unit 130 activates a retransmission counter (Retx-Counter) 132 in response to the signal transmission / reception unit 110 newly transmitting an activation command or a deactivation command to the user apparatus 200 (for example, Retx-Counter). = 0). If the ACK is not received from the user apparatus 200 in response to the transmitted activation command or deactivation command after the retransmission counter is activated, the retransmission control unit 130 confirms whether the retransmission counter 132 has expired, and the retransmission counter 132 When the signal does not exceed the predetermined threshold, the signal transmission / reception unit 110 is instructed to regenerate the MAC CE instructing the active command or the inactive command, and the retransmission counter 132 is incremented. That is, until the retransmission counter 132 expires, the retransmission control unit 130 continues the retransmission in response to the failure to receive the ACK. Here, the case where the ACK cannot be received from the user apparatus 200 is, for example, a case where a NACK is received from the user apparatus 200 in response to the transmitted activation command or deactivation command, or a predetermined time from the user apparatus 200 This means a case in which neither ACK nor NACK has been received even if the value exceeds.

  On the other hand, in response to reaching a predetermined number of times and the retransmission counter exceeding a predetermined threshold, or in response to the activation command or the deactivation command transmitted by the signal transmission / reception unit 110, acknowledgment acknowledgment (ACK) In response to receiving, the retransmission control unit 130 ends the retransmission of the activation command or the deactivation command. That is, the termination condition of the retransmission counter 132 according to the second embodiment is that the retransmission counter 132 has expired after reaching a predetermined number of times, and that an ACK has been received for the transmitted activation command or deactivation command. .

  As can be understood from the retransmission control described above, the retransmission control unit 130 can respond to the transmission of the activation command and the deactivation command of the secondary cell even when the retransmission control such as ARQ or HARQ is applied. Then, the regeneration control of the MAC CE is performed based on the retransmission counter 132. Regarding the transmission of the activation command and / or the deactivation command to the user apparatus 200, the retransmission control unit 130 is set in retransmission control such as ARQ or HARQ while the retransmission counter 132 does not exceed a predetermined threshold. If the ACK cannot be received even after exceeding the maximum number of retransmissions, the signal transmission / reception unit 110 is instructed to regenerate the MAC CE instructing the activation command or the deactivation command.

  In one Example, the cell management part 120 sets two or more secondary cells to the user apparatus 200, and communicates with the user apparatus 200 using these secondary cells. In this case, in order to activate or deactivate any secondary cell of the plurality of secondary cells, when transmitting an activation command or deactivation command for the secondary cell to the user apparatus 200, the base station 100 transmits The standard specification stipulates that the MAC CE of the activation command or the deactivation command must be transmitted not only to the target secondary cell but also to other secondary cells set in the user apparatus 200. Yes. For example, for secondary cells that are already active among other secondary cells, the cell management unit 120 instructs the signal transmission / reception unit 110 to transmit an activation command to the user apparatus 200 in order to maintain the active state. You may make it do. On the other hand, for secondary cells that are already in an inactive state among other secondary cells, the cell management unit 120 transmits and receives a deactivation command to the user apparatus 200 in order to maintain the inactive state. 110 may be instructed.

  On the other hand, it is necessary to change the active state of any other secondary cell while the retransmission counter 132 is activated while the transmission of the activation command or the deactivation command to the secondary cell to be transmitted is started. In this case, the retransmission control unit 130 transmits a MAC CE reflecting the change in the state of the other secondary cell. Thus, when an activation command or deactivation command different from the previous one is transmitted, the retransmission control unit 130 may restart the activated retransmission counter 132 (Retx-Counter = 0). That is, if the cell management unit 120 changes the active state of another secondary cell while the retransmission control unit 130 controls the retransmission of the activation command or the deactivation command for the secondary cell to be transmitted, the retransmission control is performed. The unit 130 may reset the retransmission counter 132 and restart it. This makes it possible to reset the number of retransmission counters 132 in response to the latest transmission of the activation command or the deactivation command.

  FIG. 12 is a flowchart showing retransmission processing in the base station according to the second embodiment of the present invention. The retransmission process is started, for example, when the base station 100 attempts to set the secondary cell set in the user apparatus 200 to a communication enabled state or a communication disabled state.

  As illustrated in FIG. 12, in step S201, the base station 100 transmits an activation command or a deactivation command for activating or deactivating the secondary cell to the user apparatus 200. The activation command and the deactivation command are transmitted as a MAC CE.

  In step S202, the base station 100 activates the retransmission counter 132 having a predetermined number of times.

  In step S203, the base station 100 determines whether an acknowledgment delivery confirmation (ACK) has been received from the user apparatus 200 in response to the transmitted activation command or deactivation command. When ACK is received from the user apparatus 200 (S203: Y), the base station 100 determines that the user apparatus 200 has successfully activated the secondary cell, ends the retransmission counter 132 in step S204, and performs retransmission processing. finish. On the other hand, when ACK is not received from the user apparatus 200, such as when a NACK is received or a response is not received within a predetermined period (S203: N), the base station 100 indicates that the user apparatus 200 Is determined to have failed to be activated, and the process proceeds to step S205.

  In step S205, the base station 100 further determines whether or not the retransmission counter 132 is greater than or equal to a predetermined number. When the retransmission counter 132 is greater than or equal to the predetermined number of times (S205: Y), the base station 100 ends the retransmission counter 132 in step S204 and ends the retransmission process. On the other hand, if the retransmission counter 132 is not greater than or equal to the predetermined number of times (S205: N), the base station 100 proceeds to step S206.

  In step S206, the base station 100 again generates a MAC CE instructing an activation command or a deactivation command, transmits the MAC CE to the user apparatus 200, increments the retransmission counter 132, returns to step S203, and returns to each of the above-described steps. Repeat steps. When retransmission control such as ARQ or HARQ is applied, the base station 100 continues until the retransmission counter 132 expires or receives an ACK from the user apparatus 200 even if the maximum number of retransmissions for retransmission control is exceeded. , Repeat regeneration.

  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 Signal transmission / reception part 120 Cell management part 130 Retransmission control part 131 Retransmission timer 132 Retransmission counter 200 User apparatus

Claims (11)

A signal transmission / reception unit for communicating a radio signal with the user apparatus;
A cell management unit for managing a primary cell and a secondary cell allocated to the user apparatus for communicating the radio signal;
A retransmission control unit for managing retransmission control means for controlling retransmission of an activation command for activating the secondary cell and / or a deactivation command for deactivating the secondary cell;
A base station having
While the retransmission control unit does not satisfy a predetermined termination condition, each time the control signal indicating the activation command or the deactivation command transmitted by the signal transmission / reception unit exceeds retransmission, the retransmission control unit Instructing the signal transmitting and receiving unit to regenerate a control signal indicating the activation command or the deactivation command,
When the retransmission control unit satisfies the predetermined termination condition, the retransmission control unit instructs the signal transmitting / receiving unit to stop reinstruction of the activation command or the deactivation command. The retransmission control means is a retransmission timer having a predetermined period,
The retransmission control unit starts the retransmission timer in response to the signal transmission / reception unit newly transmitting the activation command or the deactivation command to the user device,
The retransmission control unit regenerates a control signal indicating the activation command or the deactivation command in response to not receiving the acknowledgment delivery confirmation while the retransmission timer does not expire The base station according to claim 1, wherein the base station instructs the signal transmission / reception unit to.   When ARQ (Automatic Repeat reQuest) or HARQ (Hybrid ARQ) is applied to transmission of the activation command and / or the deactivation command to the user equipment, the retransmission control unit does not expire the retransmission timer During the period, if the delivery confirmation cannot be obtained for the command even if the maximum number of retransmissions set in the ARQ or the HARQ is exceeded, the control signal indicating the activation command or the deactivation command is reproduced. The base station according to claim 2, wherein the signal transmission / reception unit is instructed to be configured. The cell management unit assigns a plurality of secondary cells to the user equipment,
While the retransmission control unit controls retransmission of the activation command or the deactivation command for the first secondary cell of the plurality of secondary cells, the cell management unit performs second secondary of the plurality of secondary cells. 3. When the cell active state is changed, the retransmission control unit reflects a change in the state of the second secondary cell in a control signal that is subsequently regenerated, resets the retransmission timer, and restarts. Or the base station of 3 description.   In the case where the signal transmission / reception unit transmits the activation command and does not receive the acknowledgment delivery confirmation for the activation command, and the retransmission timer managed by the retransmission control unit has expired, The base station as described in any one of Claims 2 thru | or 4 which considers the secondary cell which instruct | indicated the said activation command as an active state. The retransmission control means is a retransmission counter having a predetermined number of times,
The retransmission control unit starts the retransmission counter in response to the signal transmitting / receiving unit newly transmitting the activation command or the deactivation command to the user device,
The retransmission control unit regenerates a control signal indicating the activation command or the deactivation command in response to not receiving the acknowledgment delivery confirmation while the retransmission counter has not expired. The base station according to claim 1, wherein the base station instructs the signal transmission / reception unit to.   When ARQ (Automatic Repeat reQuest) or HARQ (Hybrid ARQ) is applied to transmission of the activation command and / or the deactivation command to the user apparatus, the retransmission control unit has the retransmission counter set to a predetermined value While the threshold is not exceeded, if the delivery confirmation cannot be obtained for the command even when the maximum number of retransmissions set in the ARQ or the HARQ is exceeded, the activation command or the deactivation command is indicated. The base station according to claim 6, wherein the signal transmitting / receiving unit is instructed to regenerate a control signal. The cell management unit assigns a plurality of secondary cells to the user equipment,
While the retransmission control unit controls retransmission of the activation command or the deactivation command for the first secondary cell of the plurality of secondary cells, the cell management unit performs second secondary of the plurality of secondary cells. 8. When the cell active state is changed, the retransmission control unit reflects the change in the state of the second secondary cell in a control signal regenerated thereafter, and restarts the retransmission counter. Base station.   In the case where the signal transmitting / receiving unit transmits the activation command and does not receive an acknowledgment delivery confirmation for the activation command, the retransmission counter managed by the retransmission control unit exceeds a predetermined threshold The base station according to any one of claims 6 to 8, wherein a secondary cell instructing the activation command is regarded as an active state when it is present. A method in a base station that communicates with a user equipment by carrier aggregation,
Sending an activation command for activating a secondary cell or a deactivation command for deactivating the secondary cell;
Activating a retransmission timer for controlling retransmission of the activation command and / or the deactivation command;
Generation of a MAC CE indicating the activation command and / or the deactivation command until an acknowledgment delivery acknowledgment for the transmitted activation command or deactivation command is received or until the retransmission timer expires Step to continue,
Having a method. A method in a base station that communicates with a user equipment by carrier aggregation,
Sending an activation command for activating a secondary cell or a deactivation command for deactivating the secondary cell;
Activating a retransmission counter for controlling retransmission of the activation command and / or the deactivation command;
Instruct the activation and / or deactivation command until receipt of acknowledgment of acknowledgment for the transmitted activation or deactivation command is received or until the retransmission counter exceeds a predetermined threshold Continuing to generate the MAC CE;
Having a method.

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