JP6587846B2 - User device and intermittent reception control method - Google Patents

Description

  The present invention relates to DRX control of a user apparatus in a mobile communication system such as LTE.

  In LTE (Long Term Evolution) standardized by 3GPP (3rd Generation Partnership Project), when the data transmitted and received by the user apparatus UE does not exist for a certain period or more from the viewpoint of suppressing battery consumption of the user apparatus UE, the base station eNB DRX (Discontinuous Reception) control for intermittently receiving a downlink control channel (PDCCH: Physical Downlink Control Channel) transmitted from the network only for a specific period is employed (for example, see Non-Patent Document 1).

  Specifically, in DRX control, a user apparatus connected by RRC is managed as either an Active state or an Inactive state. The user apparatus UE that has transitioned to the Active state monitors the PDCCH and transmits CSI (Channel State Information) / SRS (Sounding Reference Signal: reference signal for uplink channel quality measurement) to the base station eNB. On the other hand, since the user apparatus UE that has transitioned to the inactive state does not monitor the PDCCH and does not transmit CSI / SRS, battery consumption can be suppressed. The time in the Active state is also referred to as Active Time.

  The user apparatus UE is in the active state when, for example, when one of the On-duration Timer, drx-InactivityTimer, drx-RetransmissionTimer, or mac-contentionResolutionTimer is activated, it is retransmitted due to the H, and the Queries request is due to L. Is assigned, the Random Access Response is received, and then the PDCCH instructing new transmission is not received. Except for these cases, the user apparatus UE is in an inactive state.

  As an example, FIG. 1A illustrates an example of state transition by DRX Inactivity Timer in the user apparatus UE. As shown to Fig.1 (a), when the user apparatus UE receives the last PDCCH (step S1) and DRX-Inactivity Timer expires (step S2), it changes to Inactive, and after that, the active period is DRX cycle. Arriving periodically (step S3).

  FIG. 1B shows an example of transition by DRX command MAC control Element (DRX MAC CE). As shown in FIG. 1B, when the user apparatus UE receives the last PDCCH (step S4) and receives the DRX MAC CE (step S5), the DRX-Inactivity Timer is forcibly stopped and transitions to Inactive. Thereafter, the Active period periodically arrives in DRX cycle (step S6).

  Moreover, in the user apparatus UE and base station eNB in LTE, HARQ (Hybrid ARQ) control is performed in the HARQ entity of a MAC (Media Access Control) layer. In HARQ control, the HARQ process in the HARQ entity of the MAC processes data for each process number (for each identifier). More specifically, in the case of downlink (DL), the Asynchronous retransmission control (asynchronous retransmission control) is performed, so that the base station eNB can transmit and transmit data whenever it is away from the previous transmission for a predetermined period or longer. At this time, the HARQ process number is explicitly notified in the PDCCH.

  Further, in uplink (UL), the Synchronous retransmission control (synchronous retransmission control) is performed, so that the user apparatus UE performs retransmission at a fixed period (for example, 8 ms). The HARQ process number is uniquely determined at the PUSCH initial transmission timing, and the HARQ process number is not explicitly notified from the base station eNB.

  Another background art is LAA (Licensed Assisted Access). The current LTE system is operated in a license band assigned to a telecommunications carrier, but in order to absorb increasing user traffic, a band (unlicensed band) that can be used other than the license band is LTE. It is being considered to extend the bandwidth using the Wireless access using an unlicensed band together with a license band is called LAA.

  In the unlicensed band, communication is prohibited when there are other devices communicating at the frequency of the band. Therefore, when the user apparatus UE (and the base station eNB) performs transmission, first of all, it is confirmed whether other transmitters (eNB or LAA-UE or WiFi, etc.) are communicating, and may not be communicating. Send only if confirmed. This control is called LBT (Listen Before Talk).

3GPP TS 36.321 V12.5.0 (2015-03) R2-152417

  In DRX control, there is an opportunity for the user apparatus UE to autonomously transition to the Active state at the timing when the base station eNB is assumed to transmit the PDCCH even in the Inactive state.

  That is, regarding the DL, after the base station eNB newly transmits the DL, if the user apparatus UE transitions to the Inactive state before performing retransmission (by a very short drx-InactivityTimer), the base station eNB Resource allocation for retransmission cannot be performed. Therefore, when the PDSCH decoding result is NG, control using drx-RetransmissionTimer is introduced as control for the user apparatus UE to autonomously transition to the Active state.

  Specifically, the user apparatus UE manages the HARQ RTT timer and the drx-RetransmissionTimer for each HARQ process. When the PDSCH decoding result is NG, the user apparatus UE activates the HARQ RTT timer of the corresponding HARQ process, activates the drx-RetransmissionTimer when the HARQ RTT timer expires, and maintains the Active state while the timer is activated.

  When the user apparatus UE receives allocation information (DCI in PDCCH) of the corresponding HARQ process before the expiration of the drx-RetransmissionTimer, the user apparatus UE stops the drx-RetransmissionTimer. If the decoding result is NG, the HARQ RTT timer is activated again.

  When drx-RetransmissionTimer expires, the state transits to the Inactive state. However, it may be in an Active state depending on other conditions.

  Regarding UL, as described above, HARQ retransmission is basically Sync retransmission (the UE autonomously triggers retransmission at a period of 8 ms even if there is no instruction from the eNB). In order to change, it is necessary to transmit PDCCH in a subframe 4 ms before retransmission. Therefore, it is defined that the user apparatus UE autonomously transitions to the Active state in anticipation of the PDCCH from the base station eNB when retransmission data is still in the buffer.

  Here, when LAA is considered, since the user apparatus UE may be prevented from HARQ retransmission by LBT = busy, it has been agreed to adopt Async retransmission also for UL in 3GPP standardization.

  When the Asynchronous retransmission is introduced into the UL, the user apparatus UE may receive the UL grant in all subframes after receiving an instruction for new transmission (or performing new transmission). Since the battery is wasted, it is necessary to transition to the Inactive state if the UL grant cannot be received even after a certain period of time. Therefore, introduction of control by drx-Retransmission is also studied in UL (Non-patent Document 2).

  However, the drx-RetransmissionTimer control for the UL has not been proposed yet, and it is difficult for the prior art to appropriately perform the intermittent reception control related to the UL retransmission control.

  The present invention has been made in view of the above points, and provides a technique that enables a user apparatus in a mobile communication system supporting intermittent reception control to appropriately perform intermittent reception control related to uplink retransmission control. The purpose is to do.

According to an embodiment of the present invention, a user apparatus in a mobile communication system supporting discontinuous reception control,
A timer that activates the first timer when receiving downlink control information including resource allocation information for uplink data transmission from the base station, and activates the second timer when the first timer expires Control means;
Receiving control means for bringing the user device into an active state when the second timer is running ,
The timer control means activates the first timer at a timing of performing uplink data transmission based on the downlink control information, and sets downlink control information for uplink data transmission before the second timer expires. A user device is provided that stops the second timer when received from a base station .

Moreover, according to the embodiment of the present invention, there is an intermittent reception control method executed by a user apparatus in a mobile communication system that supports intermittent reception control,
When downlink control information including resource allocation information for uplink data transmission is received from the base station , the first timer is started at the timing of performing uplink data transmission based on the downlink control information, and the first timer When running, do not monitor downlink control channel,
If the first timer has expired, then start the second timer, when the second timer has been started, have rows monitoring of the downlink control channel, the second timer expires Previously, there is provided an intermittent reception control method for stopping the second timer when downlink control information for uplink data transmission is received from the base station .

  According to the embodiment of the present invention, a technique is provided that enables a user apparatus in a mobile communication system supporting intermittent reception control to appropriately perform intermittent reception control related to uplink retransmission control.

It is a figure for demonstrating DRX control. It is a block diagram of the communication system in embodiment of this invention. It is a figure which shows the operation example in connection with the setting of the communication system which concerns on embodiment of this invention. It is a figure for demonstrating the basic operation example (basic example) in embodiment of this invention. It is a flowchart which shows operation | movement of the user apparatus UE corresponding to a basic example. It is a figure for demonstrating the subject in a basic example. It is a figure for demonstrating a modification. It is a flowchart which shows operation | movement of the user apparatus UE corresponding to a basic example. It is a figure which shows the example of a change of a standard specification. It is a block diagram of the user apparatus UE.

  Embodiments of the present invention will be described below with reference to the drawings. The embodiment described below is only an example, and the embodiment to which the present invention is applied is not limited to the following embodiment. For example, it is assumed that the communication system according to the present embodiment is compatible with LTE including LTE-Advanced, but the present invention is not limited to LTE, and communication systems of other systems that support discontinuous reception control. It is also applicable to.

  Further, CA (carrier aggregation) in the present embodiment includes not only intra-eNB CA but also inter-eNB CA such as DC (Dual connectivity). Moreover, in this Embodiment, CC and a cell may be considered fundamentally synonymous and CC may be called a cell (more specifically, a serving cell).

(Overall system configuration, operation overview)
FIG. 2 shows a configuration diagram of a communication system according to the embodiment of the present invention. The communication system according to the present embodiment is an LTE communication system, and includes a user apparatus UE and a base station eNB as shown in FIG. The communication system supports DRX control.

  FIG. 2 shows one user apparatus UE and one base station eNB, but this is an example, and there may be a plurality of user apparatuses UE and base stations eNB. For example, by applying CA, the base station eNB can form a plurality of cells independently. For example, by remotely connecting an RRE (remote radio apparatus), a plurality of cells can be formed between the base station eNB main body and the RRE. It can also be formed. Moreover, the user apparatus UE may be provided with the capability (Dual Connectivity) which communicates with the some base station eNB simultaneously.

  In addition, when CA is performed, a PCell (Primary cell) that is a highly reliable cell that ensures connectivity and an SCell (Secondary cell) that is an accompanying cell are set for the user apparatus UE. . First, the user apparatus UE can connect to the PCell and add an SCell as necessary. The PCell is a cell similar to a single cell that supports RLM (Radio Link Monitoring), SPS (Semi-Persistent Scheduling), and the like. The addition and deletion of the SCell is performed by RRC (Radio Resource Control) signaling.

  Further, when performing dual connectivity, the user apparatus UE performs communication using radio resources of two physically different base stations eNB at the same time. Dual connectivity is a type of CA, also called Inter eNB CA (inter-base station carrier aggregation), and introduces Master-eNB (MeNB) and Secondary-eNB (SeNB). In DC, a cell group composed of cells (one or more) under the MeNB is defined as an MCG (Master Cell Group, master cell group), and a cell group composed of cells (one or a plurality) under the SeNB is defined as SCG ( (Secondary Cell Group, secondary cell group). A UL CC is set in at least one SCell of the SCGs, and a PUCCH is set in one of them. This SCell is called PSCell (primary SCell).

  When CA (including DC) is performed, DRX control described in the present embodiment may be performed for each CC, or may be performed for each group (cell group) including a plurality of CCs.

  As one of basic operations of the mobile communication system according to the present embodiment, notification of UE capability information (UE capability) for notifying the capability of the user apparatus UE from the user apparatus UE to the base station eNB, and the base There is a notification of RRCConnectionReconfiguration that notifies various setting information (configuration) related to RRC connection or the like from the station eNB to the user apparatus UE. With these operations, the base station eNB can set the DRX operation for the user apparatus UE and various timers related to DRX in consideration of the capability of the user apparatus UE.

  These notification operation examples will be described with reference to FIG. As shown in FIG. 3, the user apparatus UE receives a UE capability information request (UE capability inquiry) transmitted from the base station eNB in step S101. Based on the UE capability information request, the user apparatus UE transmits UE capability information (UE capability information) to the base station eNB (step S102). In step S103, RRCConnectionReconfiguration is notified from the base station eNB to the user apparatus UE. The user apparatus UE that has received the RRCConnectionReconfiguration sets (stores) the notified various configurations, and transmits the RRCConnectionReconfigurationComplete to the base station eNB in step S104. The RRCConnectionReconfiguration includes setting information (DRX-config or the like) related to DRX.

  In the following, a basic example that is a basic operation example in the present embodiment and a modified example in which the basic example is developed will be described.

(Basic example)
In the present embodiment, in HARQ control, the same Async retransmission is performed in the UL as in the DL. That is, the base station eNB can always transmit the PDCCH (UL grant) to the user apparatus UE if the previous (first) UL transmission and the current transmission (retransmission) are separated by a predetermined period or more. . Moreover, in this Embodiment, it is assumed that the HAEQ process number (identifier) of UL is notified to the user apparatus UE from the base station eNB. However, instead of this, the HARQ process number determined by the user apparatus UE at the PUSCH initial transmission timing may be notified to the base station eNB using PUSCH or PUCCH.

  Note that UL Async retransmission control can be suitably used in LAA, but in the present embodiment, the band used is not limited to LAA, and the band used may be an unlicensed band or a licensed band.

  In the present embodiment, a UL HARQ RTT timer and a drx-RetransmissionTimer for UL are used for DRX control related to UL HARQ control. The values of these timers are transmitted from the base station eNB to the user apparatus UE in step S103 of FIG. 3, for example. Hereinafter, unless otherwise specified, HARQ RTT timer and drx-RetransmissionTimer each mean a timer for UL.

  Hereinafter, an example of control using the HARQ RTT timer and the drx-RetransmissionTimer will be described with reference to FIG.

  In the user apparatus UE, UL data transmission is triggered, and for example, an UL grant (downlink control information including UL resource allocation information) is transmitted from the base station eNB to the user apparatus UE through transmission of SR (scheduling request) or the like. Sent. The user apparatus UE receives the UL grant at the time indicated by A in FIG. 4 (that is, successfully decodes the DCI), and activates the HARQ RTT timer at that timing (step S201).

  For the UL transmission shown in FIG. 4, 0 is assigned as the HARQ process number. In the present embodiment, the HARQ process number is included in the UL grant, and the user apparatus UE assigns the HARQ process number to the UL transmission. Recognized and managed as the number of the HARQ process that processes the UL data to be transmitted by the PUSCH resource allocated by the grant. That is, the HARQ RTT timer activated in step S201 is associated with the HARQ process number. In addition, a drx-RetransmissionTimer described later is also managed in association with the HARQ process number.

  After starting the HARQ RTT timer in step S201 of FIG. 4, the user apparatus UE is in an inactive state and does not monitor (monitor) the PDCCH while the timer is being started (before stopping or before expiration). May be. That is, while the HARQ RTT timer is activated, the user apparatus UE is allowed to enter the inactive state. While the timer is activated, the user apparatus UE is set to an inactive state so that PDCCH is not monitored, so that battery saving during activation of the HARQ RTT timer can be achieved. However, it is not essential that the user apparatus UE be in an inactive state (not to monitor PDCCH) while the timer is activated, and control is performed so that the user apparatus UE is not in an inactive state while the timer is activated. It is also possible. Even in this case, since there is a drx-RetransmissionTimer, there is an effect of battery saving.

  For example, the value of the HARQ RTT timer is set as a time length in which it is assumed that the next UL grant is not received after the UL grant of the HARQ process is received.

  At the time shown in B of FIG. 4, the user apparatus UE performs UL data transmission using the PUSCH resource allocated by the UL grant received at the time A.

  Note that the UL grant serving as a trigger for starting the HARQ RTT timer may be all UL grants, or may be limited to a UL grant having a specific DCI. The specific DCI is, for example, a DCI including a HARQ process number or RV (Redundancy version).

  In the example of FIG. 4, the user apparatus UE activates the HARQ RTT timer at the timing of receiving the UL grant. However, this is an example, and the user apparatus UE may be activated at a timing other than this. For example, the HARQ RTT timer may be activated at the timing when data transmission is performed using the PUSCH indicated by B in FIG. In the user apparatus UE, data transmission by PUSCH is attempted. However, when UL LBT = busy, or when the PUSCH transmission timing overlaps with the measurement gap, data transmission cannot actually be performed. In this embodiment, even in such a case, the HARQ RTT timer may be activated at the timing when PUSCH transmission is attempted. Accordingly, when the UL data cannot be actually transmitted, the Active state is not continued as it is, so that it is possible to receive the UL grant for retransmission from the base station eNB while suppressing battery consumption.

  In the example of FIG. 4, the base station eNB fails to decode the data transmitted from the user apparatus UE at the time point B (CRC = NG). Thereafter, in the user apparatus UE, the HARQ RTT timer expires as shown in step S202. In step S202, the user apparatus UE activates the drx-RetransmissionTimer that is managed for the HARQ process.

  While the drx-RetransmissionTimer is activated, the user apparatus UE is in the Active state and monitors the PDCCH. That is, the DCI decoding process is executed in the subframe that receives the PDCCH.

  As described above, the value of drx-RetransmissionTimer is basically notified from the base station eNB to the user apparatus UE. However, only the value of the drx-RetransmissionTimer for DL may be notified, and the value of the drx-RetransmissionTimer for DL may be used without notifying the value of the drx-RetransmissionTimer for UL. Also, the value of the drx-RetransmissionTimer may be notified for each DL / UL. Also, the value of drx-RetransmissionTimer may be set for each UE (the same value regardless of the carrier and cell in the UE), or different values are set for the carrier of the license band and the carrier of the unlicensed band. May be. Moreover, the value of drx-RetransmissionTimer may be set for each cell set in the UE.

  In the example of FIG. 4, before the expiration of drx-RetransmissionTimer, UL grant for UL retransmission is transmitted from the base station eNB to the user apparatus UE with respect to the HARQ process, and the user apparatus UE receives the UL grant at the time of C. Receive.

  When receiving the UL grant, the user apparatus UE stops the drx-RetransmissionTimer for the HARQ process and activates the HARQ RTT timer. After starting the HARQ RTT timer, the same operations as those after step S201 are performed.

  Regarding the timing of stopping the drx-RetransmissionTimer and starting the HARQ RTT timer, the drx-RetransmissionTimer is stopped and the HARQ RTT timer is started at the timing when data transmission by PUSCH shown in FIG. 4D is performed. Also good. Alternatively, the drx-RetransmissionTimer may be stopped at the UL grant reception timing, and the HARQ RTT timer may be activated at the PUSCH transmission timing.

  In addition, although data transmission by PUSCH was attempted, even when data transmission could not be actually performed, at the timing when PUSCH transmission was attempted, drx-RetransmissionTimer was stopped or HARQ RTT timer was started. Also good.

  The data transmitted at the time point D in FIG. 4 is normally received at the base station eNB. In the example of FIG. 4, the HARQ RTT timer expires in step S204, the drx-RetransmissionTimer starts at that time, and the user apparatus UE enters an active state.

  As in the example of FIG. 4, when the PUSCH retransmission at time D is successful, the retransmission UL grant is not received after that, and setting the Active state after step S204 may waste power. . However, since it is assumed that PHICH (ACK / NACK for uplink data transmission) is not applied in the UL Async retransmission of the LAA cell or the like, the user apparatus UE cannot know that the PUSCH retransmission at the time D is successful. However, since it is necessary to prepare for subsequent retransmission UL grant reception, it is meaningful to set the active state after step S204. The period in which the active state is maintained is limited by the drx-RetransmissionTimer introduced in the present embodiment. Therefore, the drx-RetransmissionTimer is effective in reducing the battery even in the control described above.

<Operation of User Device UE in Basic Example>
FIG. 5 is a flowchart showing an operation of the user apparatus UE corresponding to the basic example. With reference to FIG. 5, the operation of the basic example described in FIG. 4 will be described from the viewpoint of the user apparatus UE. The example of FIG. 5 is an example in which a timer (HARQ RTT timer) is started at the PUSCH transmission timing and the timer (drx-RetransmissionTimer) is stopped at the UL grant reception timing. In the following example, the specific name of “timer” described in the flowchart is described in parentheses.

  In step S301, the user apparatus UE performs data transmission by PUSCH for a certain HARQ process. The operations described below are operations related to the HARQ process. Data transmission in step S301 may be initial transmission or retransmission. In step S302, the user apparatus UE starts a timer (HARQ RTT timer). In step S302, when the timer (HARQ RTT timer) expires, the timer (drx-RetransmissionTimer) is started.

  While the timer (drx-RetransmissionTimer) is being activated, the user apparatus UE monitors the PDCCH to confirm whether or not the UL grant (scheduling information) of the corresponding HARQ process is received. Specifically, the user apparatus UE monitors whether or not the UL grant including the HARQ process number is received. For example, even if the UL grant addressed to itself is received, if the HARQ process number of interest is not included, the determination in step S303 is not Yes. Step S303 indicates a single PDCCH reception timing.

  When the determination result in step S303 is Yes (when the UL grant for the target HARQ process is received), the user apparatus UE stops the timer (drx-RetransmissionTimer) of the HARQ process. Thereafter, the processing from step S301 described above is performed.

  If the determination result in step S303 is No (when the UL grant for the target HARQ process is not received at the PDCCH reception timing), the process proceeds to step S305, and if the timer (drx-RetransmissionTimer) has not expired, the PDCCH Monitoring (monitoring) is continued (No in step S305, step S303).

  In step S305, when the timer (drx-RetransmissionTimer) expires, the process related to the target HARQ process is terminated.

<Application of this control>
The DRX control using the timer in the present embodiment may be applied only when the base station eNB instructs the user apparatus UE to perform the DRX control. In addition, this control may be applied only when an instruction to perform UL Async retransmission control is given from the base station eNB to the user apparatus UE.

  When neither of the above instructions is given, the user apparatus UE performs a conventional operation. Alternatively, the user apparatus UE enters the Inactive state after receiving the UL grant for the first UL transmission (or the first PUSCH transmission), and performs other conditions such as drx− without performing control to autonomously enter the Active state. You may employ | adopt the operation | movement which expects to be in an Active state by starting of InactivityTimer.

  The instruction from the base station eNB regarding whether or not to apply this control may be performed on a CC (cell) basis, a cell type such as a cell using a license band, a cell using an unlicensed band, or a frequency band. It may be performed in units, or may be specified in units of cell groups obtained by grouping cells.

  The signal used for the instruction is not limited to a specific signal, and may be any layer signal such as an RRC signal, a MAC signal, and a PHY signal. Further, the user apparatus UE may notify the base station eNB that it has a function of performing this control as capability information, and the base station eNB may control the instruction in consideration of the capability information. For example, if the user apparatus UE does not have a function of performing this control, the base station eNB does not issue an instruction to perform this control.

(Modification)
In a situation where the PHICH assumed as an example in the present embodiment is not applied (LAA cell or the like), as described with reference to FIG. Therefore, it is meaningful to maintain the Active state in the user apparatus UE for a predetermined time (drx-InactivityTimer time).

  However, as illustrated in A of FIG. 6, even when retransmission is successful (when the CRC for PUSCH data is OK on the base station eNB side), the user apparatus UE continues to be in the Active state. This is a waste of battery.

  Therefore, in the modification, the base station eNB explicitly instructs the user apparatus UE to stop the timer. The timer is one of HARQ RTT timer and drx-RetransmissionTimer, and is an active timer. Here, a signal for instructing timer stop is referred to as a timer stop instruction signal. The timer stop instruction signal is a physical signal such as PDCCH, for example. The timer stop instruction signal may be a MAC signal (MAC CE). In addition, the timer stop instruction signal may be transmitted, for example, with a predetermined resource in a subframe every subframe (or a predetermined plurality of subframes). Thereby, the user apparatus UE does not always need to monitor the timer stop instruction signal, and only needs to monitor at a timing at which the user apparatus UE may receive the timer stop instruction signal.

  FIG. 7 is a diagram illustrating an operation example in the modification. Steps S401 to S404 in FIG. 7 are the same as steps S201 to S204 in the basic example shown in FIG. In the modification shown in FIG. 7, when the base station eNB succeeds in decoding (becomes CRC OK) with respect to the retransmission data transmitted at the time point D for the target HARQ process, the base station eNB instructs the timer to stop. A signal is transmitted to the user apparatus UE. This timer stop instruction signal includes the HARQ process number for identifying the HARQ process of the timer to be stopped. In addition to the timer stop instruction control for each HARQ process, control for each UE may be used. In the case of UE unit control, the HARQ process number is not included in the timer stop instruction signal, and the user apparatus UE performs the following control for all the HARQ processes whose timers are being activated.

  At time E, the user apparatus UE receives the timer stop instruction signal and stops the drx-RetransmissionTimer that is being activated. The user apparatus UE that has stopped the drx-RetransmissionTimer enters the Inactive state unless there is a trigger for transition to the Active state.

  In the example of FIG. 7, an example in which the timer stop instruction signal is received during the start of the drx-RetransmissionTimer is shown, but when the timer stop instruction signal is received during the start of the HARQ RTT timer, the HARQ RTT timer is received. May be stopped. In this case, the drx-RetransmissionTimer is not activated with the stop of the HARQ RTT timer. In this case, the user apparatus UE can receive the timer stop instruction signal even when the HARQ RTT timer is being activated (inactive state).

  In the user apparatus UE of the present embodiment, basically, even when the drx-RetransmissionTimer corresponding to a certain HARQ process expires, the UL data buffer corresponding to the HARQ process is not flushed (erased). This is because the UL data can be retransmitted even after the drx-RetransmissionTimer expires.

  On the other hand, in the control according to the present modification, when receiving a timer stop instruction signal from the base station eNB, the user apparatus UE may stop the timer and flush the buffer of the corresponding HARQ process. For example, when the retransmission is successful, the timer stop instruction signal is transmitted from the base station eNB to the user apparatus UE. In this case, by flushing a buffer storing UL data that does not need to be retransmitted, the user apparatus UE It is possible to efficiently use the buffer area in the other process.

  Further, when receiving a timer stop instruction signal from the base station eNB, the user apparatus UE may stop the timer and consider LBT = busy for the corresponding HARQ process. Existing LBT is usually controlled in units of UEs, but in this modification, it is controlled in units of HARQ processes.

  In the present embodiment, the user apparatus UE may autonomously stop the timer in addition to stopping the timer by the explicit timer stop instruction signal from the base station eNB as described above.

  In the control for autonomously stopping the timer, the user apparatus UE manages a counter for each UL HARQ process, and counts the number of times of receiving a DL signal for the HARQ process (eg, UL grant). When the user apparatus UE detects that the count has reached a predetermined number (or has reached a value greater than that), the user apparatus UE subsequently triggers a corresponding HARQ RTT timer (DL signal). Even if there is reception or UL data transmission), the HARQ RTT timer is not activated. As a result, drx-RetransmissionTimer is not activated either.

  Further, the user apparatus UE may count the number of times of transmitting UL data (in PUSCH) for the HARQ process. Also in this case, when the user apparatus UE detects that the count has reached a predetermined number (or has reached a value greater than that), the user apparatus UE subsequently triggers a corresponding HARQ RTT timer ( Even if there is DL signal reception or UL data transmission), the HARQ RTT timer is not activated. As a result, drx-RetransmissionTimer is not activated either.

  Further, when the user apparatus UE detects that the count number (DL signal reception number or DL data transmission number) has reached a predetermined number (or a value higher than that), the corresponding HARQ When the RTT timer or the corresponding drx-RetransmissionTimer is being activated, the HARQ RTT timer or the drx-RetransmissionTimer may be stopped. Either the stop control or the non-activation control described above may be performed, or both may be performed.

  For example, the predetermined number of times is notified in advance from the base station eNB to the user apparatus UE in the RRC layer or the like. In addition, when the counter reaches a predetermined number of times (or when it reaches a value larger than that), the user apparatus UE may flush (flash) the corresponding HARQ buffer.

  Note that the user apparatus UE may perform both the timer stop control by the timer stop instruction signal and the above-described autonomous control.

<Example of using DRX command MAC CE as a timer stop instruction signal>
As described above, the timer stop instruction signal may be a physical signal or a MAC signal. Hereinafter, an example in which DRX command MAC CE is used as the timer stop instruction signal will be described.

  As described with reference to FIG. 1, in the prior art, when the user apparatus UE explicitly receives a DRX transition instruction from the base station eNB by the DRX command MAC CE, the user apparatus UE stops the On duration timer and the drx-InactivityTimer. To transit to the Inactive state.

  Here, in a cell (for example, LAA cell) in which UL Asynchronous retransmission control assumed in this embodiment is set, drx-RetransmissionTimer expects a scheduling delay due to LBT = busy or the like on the base station eNB side. There is a possibility that the value is set to a long value, and when such a long drx-RetransmissionTimer is activated, the user apparatus UE may maintain the Active state for a long time.

  Therefore, in the present modification, when the user apparatus UE receives the DRX command MAC CE from the base station eNB, the activated drx-RetransmissionTimer is stopped. Note that Long DRX command MAC CE may be used instead of DRX command MAC CE. Hereinafter, unless otherwise specified, “DRX command MAC CE” includes Long DRX command MAC CE as its meaning.

  In this control example, all the drx-RetransmissionTimers that are running may be stopped or some drx-RetransmissionTimers may be stopped by the DRX command MAC CE. When some drx-RetransmissionTimers are stopped, the HARQ process number (identifier) to be stopped is specified by the DRX command MAC CE in order to specify which HARQ process the timer is.

  Also, as described above, the UL data buffer of the HARQ process corresponding to the drx-RetransmissionTimer to be stopped may be flushed.

  Further, when receiving the DRX command MAC CE (Long DRX command MAC CE) while starting the HARQ RTT timer, the user apparatus UE stops the HARQ RTT timer in the same manner as when stopping the drx-RetransmissionTimer. It is good as well.

  In addition, the opportunity for the base station eNB to transmit the DRX command MAC CE as the timer stop instruction signal to the user apparatus UE is not limited to a specific opportunity, but as an example, the base station eNB transmits an RRCConnectionReconfigurationComplete from the user apparatus UE. After that, when it is determined that there is no UL data transmission for a certain period, DRX command MAC CE as a timer stop instruction signal can be transmitted.

<Operation of User Device UE in Modification>
FIG. 8 is a flowchart illustrating an operation example of the user apparatus UE corresponding to the modification. With reference to FIG. 8, the operation of the modification described in FIG. 7 will be described from the viewpoint of the user apparatus UE. The example of FIG. 8 is an example of starting the timer (HARQ RTT timer) at the PUSCH transmission timing and stopping the timer (drx-RetransmissionTimer) at the UL grant reception timing, as in the case of FIG. In the following example, it is assumed that a timer stop instruction signal is received while drx-RetransmissionTimer is activated.

  In step S501, the user apparatus UE performs data transmission by PUSCH for a certain HARQ process. This data transmission may be an initial transmission or a retransmission. In step S502, the user apparatus UE starts a timer (HARQ RTT timer). In step S502, when the timer (HARQ RTT timer) expires, the timer (drx-RetransmissionTimer) is started.

  In a state where the timer (drx-RetransmissionTimer) is being activated, the user apparatus UE determines whether or not a timer stop instruction signal designating the corresponding HARQ process has been received. If the timer stop instruction signal is received (Yes in step S503), the timer (drx-RetransmissionTimer) is stopped (step S505), and if there is a next PUSCH transmission, the processing from step S501 is performed. In addition, when it becomes Yes at step S503, it is good also as shifting to completion | finish (END).

  When the determination result in Step S503 is No (when the timer stop instruction signal is not received), in Step S504, whether the user apparatus UE receives the UL grant (scheduling information) of the corresponding HARQ process, PDCCH Monitor.

  When the determination result in step S504 is Yes (when the UL grant for the target HARQ process is received), the user apparatus UE stops the timer (drx-RetransmissionTimer).

  If the determination result in step S504 is No (when the UL grant for the target HARQ process is not received at the PDCCH reception timing), the process proceeds to step S506, and if the timer (drx-RetransmissionTimer) has not expired, the timer is stopped. The instruction signal monitoring and the PDCCH monitoring are continued (No in step S506, steps S503 and S504).

  In step S506, when the timer (drx-RetransmissionTimer) expires, the process related to the target HARQ process is terminated.

(Example of changes to standard specifications)
FIG. 9 is a diagram showing a modified example (extract) of a standard specification corresponding to the mobile communication system in the present embodiment. FIG. 9 shows a modification in “5.7 Distinct Reception (DRX)” of Non-Patent Document 1 (3GPP TS 36.321). The changes are underlined. In addition, this example of a change is an example and the change of a specification is not necessarily restricted to this.

  As shown in FIG. 9, “drx-RetransmissionTimer_UL (one per UL HARQ process)” and “UL HARQ RTT Timer per UL HARQ process” which are the timers described in the present embodiment are added. More specifically, “the Active Time includes the time while: …… or drx-RetransmissionTimer_UL is running;”, “… if a UL_HARQ RTT Timer expires in this subframe: -start the drx-RetransmissionTimer_UL for the corresponding HARQ process. As described in “...”, the user apparatus UE starts the UL drx-RetransmissionTimer when the UL HARQ RTT Timer expires, and indicates that it is in the Active state while the drx-RetransmissionTimer is activated. Has been.

  Further, as described in "if a DRX Command MAC control element or a Long DRX Command MAC control element is received: ...... stop UL_HARQ RTT Timer (s) and drx-RetransmissionTimer_UL (s)." When the DRX Command MAC CE is received, the UL HARQ RTT Timer and the UL drx-RetransmissionTimer are stopped.

  Also, this specification as described in `` if the serving cell is configured with Async UL HARQ and UL grant is received on this serving cell in this subframe: -start the UL HARQ RTT Timer for the corresponding HARQ process; '' In the example of the document, in the serving cell in which Async UL HARQ (ULAsync retransmission control) is set, when receiving the UL grant, the user apparatus UE starts the UL HARQ RTT Timer for the HARQ process specified by the UL grant.

(Device configuration)
Next, a main configuration of the user apparatus UE capable of executing the operations described so far (including the basic example and the modified example) will be described. FIG. 10 shows a configuration diagram of the user apparatus UE according to the present embodiment.

  As illustrated in FIG. 10, the user apparatus UE includes a DL signal reception unit 101, a UL signal transmission unit 102, an RRC management unit 103, a DRX control unit 104, a timer management unit 105, and a UL signal generation unit 106. FIG. 10 shows only functional units that are particularly related to the embodiment of the present invention in the user apparatus UE, and has at least a function (not shown) for performing an operation based on LTE. Further, the functional configuration shown in FIG. 10 is merely an example. As long as the operation according to the present embodiment can be executed, any name may be used for the function classification and the function unit. In addition, the user apparatus UE may have a function of performing all operations of the basic example and the modified example, or may have a function of only the basic example.

  The DL signal receiving unit 101 includes a function of wirelessly receiving various signals from the base critical station eNB and acquiring a higher layer signal from the received physical layer signal.

  The UL signal transmission unit 102 includes a function of wirelessly transmitting the UL signal generated by the UL signal generation unit 106. In FIG. 10, a DRX control unit 104, a timer management unit 105, and a UL signal generation unit 106 particularly related to the present embodiment, and a UL signal transmission unit 102 that performs processing related to UL other than these functions are provided. They are listed separately. In addition to the illustrated configuration, a configuration in which the UL signal generation unit 106 and the like are included in the UL signal transmission unit 102 may be adopted.

  The RRC management unit 103 includes a function of performing various settings (configuration) while performing transmission and reception of RRC messages with the base station eNB via the DL signal reception unit 101 / UL signal transmission unit 102. In addition, the RRC management unit 103 holds information on the capability of the user apparatus UE, creates an RRC message that notifies the capability information, and transmits the RRC message to the base station eNB via the UL signal transmission unit 102. The RRC management unit 103 also has a function of receiving a value of HARQ RTT timer, a value of drx-RetransmissionTimer, and the like from the base station eNB, and passing these values to the timer management unit 105.

  The DRX control unit 104 executes the DRX control related to UL retransmission described in the present embodiment. The timer activation / deactivation described with reference to FIGS. 4, 5, 7, and 8 is performed. Stop control, control of Active / Inactive state transition, and the like are executed. That is, when the DRX control unit 104 receives downlink control information (UL grant, DCI, etc.) including resource allocation information for uplink data transmission from the base station, the DRX control unit 104 (for example, HARQ RTT for UL) When the first timer expires and the first timer expires, the timer control unit that activates the second timer (for example, drx-RetransmissionTimer for UL) and the second timer are activated And a reception control unit that activates the user apparatus. The reception control unit may have a function of allowing the user device to be deactivated when the first timer is activated. “Allowing” includes that the DRX control unit 104 deactivates the user apparatus. Further, the DRX control unit 104 includes a timer stop control function by a timer stop instruction signal and a function to perform autonomous timer non-start / stop by a counter.

  The timer management unit 105 is a functional unit that manages timers such as HARQ RTT timer and drx-RetransmissionTimer. The timer management unit 105 starts / stops a timer based on a start instruction from the DRX control unit 104, and when the timer expires, the DRX control unit 104 It has a function of notifying the expiration date. The timer management unit 105 also manages a counter that counts the number of DL signal reception / UL data transmission described above.

  The UL signal generation unit 106 has a function of converting UL data from an upper layer into a lower signal (data) and passing it to the UL signal transmission unit 102. The UL signal generation unit 106 includes a buffer that temporarily holds the UL signal (data).

  As described above, in the present embodiment, in the mobile communication system that supports intermittent reception control, when downlink control information including resource allocation information for uplink data transmission is received from a base station In addition, when the first timer is started and the first timer expires, timer control means for starting the second timer, and when the second timer is started, the user device is There is provided a user apparatus including reception control means for making an active state.

  With the above configuration, a user apparatus in a mobile communication system that supports intermittent reception control can appropriately perform intermittent reception control related to uplink retransmission control.

  The timer control means, for example, starts the first timer at the timing when the downlink control information is received from the base station, or the first timer at the timing when uplink data transmission based on the downlink control information is performed. Start up. With this configuration, timer start control can be performed at a clear timing.

  The timer control means activates the first timer even when the uplink data transmission cannot be executed when the first timer is activated at a timing of performing uplink data transmission based on the downlink control information. It is good. With this configuration, battery saving can be effectively realized.

  The downlink control information includes an identifier of a HARQ process corresponding to the uplink data transmission, and the timer control unit starts the first timer corresponding to the HARQ process identified by the identifier, and sends the HARQ process to the HARQ process. The corresponding second timer may be started. With this configuration, intermittent reception control related to uplink retransmission control can be appropriately performed for each HARQ process.

  The timer control means may stop the second timer when downlink control information for uplink data transmission is received from the base station before the second timer expires. With this configuration, it is possible to avoid unnecessarily continuing the active state, and it is possible to effectively realize battery saving.

  The timer control means may stop an activated timer of the first timer and the second timer when receiving a timer stop instruction signal from the base station. With this configuration, it is possible to avoid unnecessarily continuing the active state, and it is possible to effectively realize battery saving. For example, a DRX command MAC control element can be used as the timer stop instruction signal.

  In addition, when the user apparatus executes uplink asynchronous retransmission control according to the setting from the base station, the timer control means executes timer control using the first timer and the second timer. It is good. With this configuration, when the user apparatus executes uplink asynchronous retransmission control, intermittent reception control related to uplink retransmission control can be appropriately performed.

  The timer control means counts the number of times of receiving downlink control information or the number of times of transmitting uplink data, and when the counted number is equal to or greater than a predetermined number, It is good also as not starting or stopping the timer which is starting. With this configuration, the user apparatus can autonomously execute the timer non-activation / stop.

  The user apparatus UE described in the present embodiment may include a CPU and a memory, and may be configured by a program being executed by a CPU (processor). The processing logic described in the embodiment The configuration may be realized by hardware such as a hardware circuit provided with a program, or a program and hardware may be mixed.

  The base station eNB described in the present embodiment may include a CPU and a memory, and may be realized by a program being executed by a CPU (processor). The processing logic described in the embodiment The configuration may be realized by hardware such as a hardware circuit provided with a program, or a program and hardware may be mixed.

  Although the embodiments of the present invention have been described above, the disclosed invention is not limited to such embodiments, and those skilled in the art will understand various variations, modifications, alternatives, substitutions, and the like. I will. Although specific numerical examples have been described in order to facilitate understanding of the invention, these numerical values are merely examples and any appropriate values may be used unless otherwise specified. The classification of items in the above description is not essential to the present invention, and the items described in two or more items may be used in combination as necessary. It may be applied to the matters described in (if not inconsistent). The boundaries between functional units or processing units in the functional block diagram do not necessarily correspond to physical component boundaries. The operations of a plurality of functional units may be physically performed by one component, or the operations of one functional unit may be physically performed by a plurality of components. For convenience of explanation, the user equipment and the base station have been described using functional block diagrams, but such equipment may be implemented in hardware, software, or a combination thereof. Software operated by a processor included in a user apparatus according to an embodiment of the present invention and software operated by a processor included in a base station are random access memory (RAM), flash memory, read-only memory (ROM), EPROM, EEPROM , A register, a hard disk (HDD), a removable disk, a CD-ROM, a database, a server, or any other suitable storage medium. The present invention is not limited to the above embodiment, and various modifications, modifications, alternatives, substitutions, and the like are included in the present invention without departing from the spirit of the present invention.

UE user apparatus eNB base station 101 DL signal reception unit 102 UL signal transmission unit 103 RRC management unit 104 DRX control unit 105 timer management unit 106 UL signal generation unit

Claims (8)

A user apparatus in a mobile communication system that supports discontinuous reception control,
A timer that activates the first timer when receiving downlink control information including resource allocation information for uplink data transmission from the base station, and activates the second timer when the first timer expires Control means;
Receiving control means for bringing the user device into an active state when the second timer is running ,
The timer control means activates the first timer at a timing of performing uplink data transmission based on the downlink control information, and sets downlink control information for uplink data transmission before the second timer expires. A user device that stops the second timer when received from a base station . The timer control means activates the first timer even when the uplink data transmission cannot be executed when the first timer is activated at the timing of performing uplink data transmission based on the downlink control information. Item 4. The user device according to Item 1 . The downlink control information includes an identifier of a HARQ process corresponding to the uplink data transmission, and the timer control unit starts the first timer corresponding to the HARQ process identified by the identifier, and sends the HARQ process to the HARQ process. The user apparatus according to claim 1 or 2 , wherein the corresponding second timer is started. Said timer control means, when receiving the timer stop instruction signal from the base station, any one of claims 1 to 3 stop timer running out of the first timer and the second timer The user device according to item 1. The user apparatus according to claim 4 , wherein the timer stop instruction signal is a DRX command MAC control element. The timer control means executes timer control using the first timer and the second timer when the user apparatus executes uplink asynchronous retransmission control according to the setting from the base station. 6. The user device according to any one of 5 to 5 . The timer control means counts the number of times downlink control information is received or the number of times uplink data is transmitted, and activates the first timer when the counted number exceeds a predetermined number. The user apparatus according to any one of claims 1 to 6 , wherein the timer that is not performed or is activated is stopped. An intermittent reception control method executed by a user apparatus in a mobile communication system that supports intermittent reception control,
When downlink control information including resource allocation information for uplink data transmission is received from the base station , the first timer is started at the timing of performing uplink data transmission based on the downlink control information, and the first timer When running, do not monitor downlink control channel,
If the first timer has expired, then start the second timer, when the second timer has been started, have rows monitoring of the downlink control channel, the second timer expires An intermittent reception control method for stopping the second timer when downlink control information for uplink data transmission is received from the base station before .

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