KR101958532B1 - Drx coordination mechanism in dual connectivity system - Google Patents

Abstract

The present invention provides a mechanism for coordinating DRX information in a dual connectivity system. A method for adjusting DRX information of a UE in a master eNB of a dual connectivity system comprises the steps of: A. receiving first information characterizing the DRX state of the UE for the secondary eNB, or displaying the DRX state of the UE to the master eNB , Sending second information to the secondary eNB, as determined by the master eNB; And B. The master eNB exchanges DRX configuration information for the auxiliary eNB and the UE. According to the mechanism for adjusting the DRX information according to the present invention, dynamic power management of the UE can be enabled, thereby reducing power consumption of the UE and improving the transmission efficiency of information.

Description

[0001] DRX COORDINATION MECHANISM IN DUAL CONNECTIVITY SYSTEM [0002]

The present disclosure relates generally to the field of wireless communications, and more particularly, to a DRX negotiation mechanism in a dual connectivity system.

The DRX may be used to reduce the power of the UE in the RRC connected state. The DRX configuration is a trade-off between power consumption and Quality of Service (QoS). In a dual connectivity system, a UE may be connected to a Master eNB (MeNB) and a Secondary eNB (SeNB), respectively, and different traffic may be transmitted via different eNBs. Accordingly, there is a need to define a DRX mechanism in a dual connectivity system.

In a conventional DRX mechanism, a UE in a radio resource control (RRC) connected state can be configured and controlled as a DRX function, so that the UE needs to always monitor the downlink channel, i.e., the PDCCH There will be no. The DRX cycle consists of two components: (1) "On Duration" during which the UE monitors the PDCCH during that time, and (2) when the UE is going to skip monitoring the downlink channel to save power during that time. DRX duration "that can be achieved. The RRC controls the operations of the DRX by configuring a number of parameters, such as the length of a short DRX cycle, the length of a long DRX cycle, the number of counts, and so on. Switching between a short DRX cycle, a long DRX cycle, and continuous reception is controlled either by a timer, or by an explicit command from an eNB. The UE monitors the PDCCH during the "on duration" of either the long DRX cycle or the short DRX cycle, when the scheduling command is received from the eNB, the UE starts an " Inactivity Timer & The PDCCH is monitored in every subframe while the inactivity timer is operating. During this duration, the UE may be considered to be in continuous receive mode. While the inactivity timer is running, the UE restarts the inactivity timer whenever a scheduling message is received on the PDCCH, and when the timer expires, the UE moves to a short DRX cycle and starts a "short DRX cycle timer ". When the timer expires, the UE moves to a long DRX cycle and therefore begins to count in a long DRX cycle. The short DRX cycle is also initiated by a MAC control element.

Based on the above procedure, most of the active duration is controlled by the scheduling command. Since there is a non-ideal backhaul of the connection between MeNB and SeNB, MeNB and SeNB support distributed scheduling, and MeNB and SeNB do not have knowledge of each other's scheduling conditions, so that the scheduling command , It may be difficult to predict how the individual timers will operate and thus aligning the DRXs of the two eNBs may make it difficult to reduce UE power consumption.

In a dual connectivity system, uplink power management is a desirable issue to be addressed. UEs supporting dual connectivity will support simultaneous uplink transmissions to MeNB and SeNB. That is, the uplink power of the UE may be shared between two eNBs. There is an ongoing discussion in 3GPP RAN1 as to whether and how to enable the UE's uplink transmit power to be dynamically shared between two eNBs. Due to the distributed scheduling by MeNB and SeNB, if there is a significant delay of non-ideal backhaul between MeNB and SeNB, scheduling information can not be exchanged, so it may be difficult for two eNBs to know each other's scheduling state, Thus, it may not be possible for them to adjust each other's power such that the total transmit power of the UE does not exceed the maximum allowed power. When the MeNB and the SeNB exchange information about the DRX duration entered by the UE for one of the eNBs (MeNB and / or SeNB), one eNB will not have uplink transmissions of the UE with other eNBs There will be a possible uplink transmission with one eNB at the maximum power of the UE and in this way there will be a better dynamic power sharing mechanism that has made it possible to improve the efficiency of the system.

However, between MeNB and SeNB, there has never been a solution for adjusting the DRX configuration and exchanging DRX related information.

In view of the above problem, the invention provides a DRX coordination mechanism that enables the eNB to effectively and dynamically manage the power of the UE.

A first aspect of the invention proposes a method of coordinating DRX information of a UE in an eNB of a dual connectivity system, comprising the steps of: A. obtaining a DRX state information of a master eNB and an auxiliary eNB; And B. The master eNB and the auxiliary eNB exchange DRX configuration information for the UE.

Preferably, Step A: when the eNB of one of the master eNB and the auxiliary eNB determines that the UE enters the DRX state for the eNB, the eNB transmits the DRX state information of the UE to the master eNB and another eNB of the auxiliary eNB ; Or the UE transmitting DRX state information for one of the master eNB and the eNB to another eNB.

Preferably, the eNB of one of the master eNB and the auxiliary eNB is configured to determine, for another eNB based on the DRX state of the UE for another eNB and / or the DRX configuration information of the UE for another eNB, whether the UE is discontinuous a time instance entering the reception state and / or a time instance when the UE terminates the discontinuous reception state and enters the continuous reception state.

Preferably, the DRX state is for the UE to enter a discontinuous reception state, and / or for the UE to terminate the discontinuous reception state and / or enter the continuous reception state, for another eNB.

Preferably, the master eNB sends its DRX configuration information to the secondary eNB in the secondary-eNB-addition message sent to the secondary eNB, and / or the master eNB receives the secondary-eNB-cell-modification message of the secondary eNB To receive DRX configuration information or DRX reconfiguration information of the auxiliary eNB; And / or one of the master eNB and the secondary eNB reconfigures its DRX configuration, one of the master eNB and the secondary eNB sends its reconstructed DRX configuration information and / or DRX state information to the other of the master eNB and the secondary eNB .

A second aspect of the invention proposes a method of coordinating DRX information of a UE in a master eNB of a dual connectivity system, comprising the steps of: A. receiving first information characterizing the DRX state of the UE for the secondary eNB , Sending to the secondary eNB secondary information determined by the master eNB, characterized by the DRX state of the UE for the master eNB; And B. The master eNB and the auxiliary eNB exchange DRX configuration information for the UE.

Preferably, the master eNB receives the first information from the UE or the auxiliary eNB; Or the master eNB receives the first information transmitted by the secondary eNB with the DRX configuration information reconstructed by the secondary eNB.

Preferably, when the master eNB reconfigures its DRX configuration information, the master eNB sends its reconstructed DRX configuration information to the secondary eNB; Or the master eNB transmits its reconstructed DRX configuration information together with the second information to the auxiliary eNB.

A third aspect of the invention proposes a method of coordinating the DRX information of a UE in a secondary eNB of a dual connectivity system, comprising the steps of: A. For the master eNB, the third Transmitting the fourth information determined by the auxiliary eNB to the master eNB, receiving the information or characterizing the DRX state of the UE for the auxiliary eNB; And B. the auxiliary eNB and the master eNB exchange DRX configuration information for the UE.

Preferably, the secondary eNB receives the third information from the UE or the master eNB; Or the secondary eNB receives the third information transmitted by the master eNB with the DRX configuration information reconstructed by the master eNB.

Advantageously, step B comprises: receiving the DRX configuration information of the master eNB by receiving the secondary-eNB-addition message of the secondary eNB from the master eNB; And / or transmitting the supplementary eNB's DRX configuration information or the reconstructed DRX configuration information by the supplemental eNB by sending the supplementary-eNB-cell-modified message for the supplementary eNB to the master eNB.

Preferably, when the secondary eNB reconstructs its DRX configuration, the secondary eNB sends its reconstructed DRX configuration information along with the fourth information to the master eNB.

Advantageously, step B further comprises: the auxiliary eNB receiving the reconfigured DRX configuration information by the master eNB.

A fourth aspect of the invention proposes a method of coordinating DRX information of a UE in a UE in a dual connectivity system, the method comprising the steps of: when the UE enters a DRX state for the first eNB, To the auxiliary eNB, the first information indicating that the mobile terminal enters the state.

According to the method of constructing the discovery durationicity of resources according to the present invention, the communication system can be avoided from collision of resources, thereby improving the use ratio of resources to ensure the reliability of communication .

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood and other objects, details, features, and advantages of the invention will become more apparent from the description of particular embodiments of the invention taken with reference to the drawings.
1 illustrates a flowchart for notifying a DRX state in a dual connectivity system in accordance with an embodiment of the invention.

Preferred embodiments of this disclosure will be described in more detail below with reference to the drawings. Although the preferred embodiments of this disclosure are illustrated in the drawings, it will be appreciated that this disclosure can be embodied in various forms, but is not limited to the embodiments described herein. On the contrary, the embodiments are provided so that this disclosure will be thorough and complete, and will convey the full scope of the disclosure to one of ordinary skill in the art.

Embodiments of the invention will be described with reference to the drawings.

1 illustrates a flowchart for notifying a DRX state in a dual connectivity system in accordance with an embodiment of the invention.

In the DRX mechanism, the UE performs DRX control functions when it is currently configured by the eNB. Since the eNB may obtain the DRX parameter configuration of the UE, the scheduling information including the PDCCH, etc., the eNB may also derive an operation related to the DRX state of the UE from the mentioned parameters and information.

When the UE enters the DRX duration for the MeNB, the time point at which the UE enters the active state for the MeNB may also be determined with it, and the length of the DRX duration may be determined by the respective parameters for the DRX state Respectively. Obviously, when the UE enters the DRX duration, the MeNB connected thereto can determine that the UE enters the DRX duration, and accordingly, the MeNB also refers to the DRX configuration parameters so that the UE is in an active state You can see the time of entry.

As will be apparent from the background in the present application, the UE will not receive downlink scheduling information from the MeNB and will not perform uplink transmissions in the DRX duration, so the UE will transmit an uplink transmission with the SeNB in the period To fully utilize the power of the UE and thus to enable dynamic power management. Obviously, SeNB needs to know the DRX duration for MeNB before this. This embodiment proposes two solutions for informing the SeNB about the information about the DRX duration entered by the UE for MeNB as follows:

In the first solution, MeNB informs SeNB about the information.

In this solution, for the DRX state of the UE for MeNB, the MeNB may determine the DRX state of the UE based on the DRX configuration information and the scheduling information. The MeNB may send information indicating the DRX status of the UE to the SeNB so that the SeNB can obtain the current DRX state of the UE for MeNB.

In a second solution, the UE directly notifies the SeNB about the information.

In this solution, the UE sends information indicating its DRX state to the MeNB to the SeNB so that the SeNB can obtain the UE's current DRX state for MeNB.

As can be appreciated, there will be no definite time point at which SeNB will receive the first information in the first solution because there is some delay in the transmission between MeNB and SeNB. Unlike the first solution, since there is an inducible delay in the transmission between the UE and the SeNB, the time point at which the SeNB receives information indicative of the DRX status of the UE for the MeNB can be derived in the second solution.

After the SeNB learns information about the UE ' s current DRX state for the MeNB, the SeNB may inform the MeNB that the UE enters a discontinuous reception state (i. E., DRX duration) and / (I. E., DRX duration) and enter a continuous receive state (i. E., Active state), or to the MeNB with reference to the UE ' s DRX configuration information for MeNB, (I.e., the DRX duration), and / or the UE may terminate the discontinuous reception state (i.e., the DRX duration) and enter the continuous reception state (i.e., active state).

In this embodiment, the MeNB transmits the DRX configuration information of the UE for the MeNB to the SeNB in the Secondary Cell Group (SCG) Add / Modify Indication message of the SeNB transmitted to the SeNB.

If the MeNB needs to reconfigure the UE with DRX information for some reason, e.g., due to a change in the type of service being transmitted, the MeNB needs to send the reconstructed DRX configuration information to the SeNB.

Optionally, at this time, the MeNB may transmit the reconstructed DRX configuration information to the SeNB along with the DRX status information corresponding to the MeNB.

After the SeNB obtains the DRX configuration information of the UE for the MeNB from the MeNB, the SeNB refers to the obtained DRX status information corresponding to the MeNB, and then, for the MeNB, the UE enters the discontinuous reception status (i.e., DRX duration) And / or the time instances at which the UE terminates the discontinuous reception state (i.e., DRX time) and enters the continuous reception state (i.e., active state).

Similarly, if the SeNB needs to transmit the DRX state information of the UE to the SeNB and the DRX configuration information of the UE for the SeNB to the SeNB, or if the UE transmits the DRX state information for the SeNB to the MeNB, , The information about the DRX state entered by the UE is known, and the time for the UE to enter the discontinuous reception state (i.e., the DRX duration) with respect to the SeNB with reference to the obtained DRX state information corresponding to SeNB Instance, and / or discontinuous reception state (i. E., DRX duration) and to be able to know precisely the time instance entering a continuous reception state (i.

In this embodiment, in the auxiliary cell group modification message, the SeNB transmits the DRX configuration information of the UE for the SeNB to the MeNB.

Similarly, when SeNB reconfigures the current DRX configuration information, the SeNB needs to send the modified DRX configuration information to the MeNB. In this embodiment, the SeNB may also transmit its reconstructed DRX configuration information to the MeNB in the SCG modification message.

As will be apparent from the above discussion, it will be appreciated that, for MeNB, the time instance in which the UE enters the discontinuous reception state (i.e., the DRX duration) and / or the UE terminates the discontinuous reception state (i.e., DRX duration) In order to accurately derive the time instance entering the state (i.e., active state), the SeNB may additionally consider the delay due to the non-ideal backhaul between MeNB and SeNB. That is, since there is some delay in the transmission between the MeNB and the SeNB, the time point at which the SeNB receives the first information is not a definite point, and the UE enters the discontinuous reception state (i.e., the DRX duration) and / A time instance that terminates a discontinuous reception state (i. E., DRX duration) and enters a continuous reception state (i. E., Active state) may be roughly derived.

In this process, the MeNB / SeNB in this process is configured such that the UE enters a discontinuous reception state (i.e., DRX duration) for another eNB (SeNB / MeNB), and / or the UE is in discontinuous reception state Period) and enters a continuous receive state (i.e., active state), thereby enabling dynamic power management. For example, when the UE is operating in the DRX duration of the MeNB, the data may be transmitted in the UE's uplink transmission to the SeNB at the UE's total power.

A plurality of non-limiting examples of DRX state information of the UE will be described below, and one of ordinary skill in the art will recognize that other DRX states of the UE are also possible.

In state 1, the UE begins to apply a long DRX cycle.

Specifically, if the UE is configured with a short DRX cycle, the UE enters state 1 when the counting drx-ShortCycleTimer expires; If the UE is configured with only a long DRX cycle, without any short DRX cycle, the UE enters state 1 when the drx-InactivityTimer expires, or when the UE receives the DRX command MAC control element.

In state 2, the UE applies a long DRX cycle, OnDurationTimer expires, while DRX-Inactivity Timer is inactive; And

The OnDurationTimer starts with the subframe of the DRX cycle and specifies the number of sub-frames of the PDCCH to be detected, so this scenario corresponds to the UE failing to decode the PDCCH in the on duration.

Accordingly, this state indicates that the UE will enter the DRX duration.

In state 3, the UE applies a long DRX cycle and the drx-Inactivity Timer starts to operate.

Contrary to state 2, this state means that the UE successfully decodes the PDCCH in the on-duration, i.e., the UE will enter a continuous reception state instead of the DRX duration.

In state 4, the UE starts to apply the system frame number (SFN) of the time instance as well as the long DRX cycle and the corresponding subframe.

In this state, a particular sub-frame or a specific time instance at which the UE starts the on duration can be determined.

In state 5, the UE begins to apply a short DRX cycle.

In response to state 1, if the UE is configured with a short DRX cycle, the UE will begin to apply a short cycle when the counting drx-InactivityTimer expires or when the UE receives the DRX command MAC control element.

In state 6, the UE applies a short DRX cycle, OnDurationTimer expires, whereas drx-InactivityTimer is inactive, i.e., the UE fails to decode the PDCCH in the on duration.

In state 7, the UE applies a short DRX cycle and the drx-Inactivity Timer starts to operate. Similarly, this state means that the UE successfully decodes the PDCCH in the on-duration, i.e., the UE will enter a continuous receive state instead of the DRX duration.

In state 8, the UE starts to apply the short DRX cycle as well as the SFN of the time instance and the corresponding subframe. In this state, the UE may initiate an on-duration and a particular sub-frame or specific time instance in the on-state may be determined.

In state 9, the UE applies a long DRX cycle and OnDurationTimer expires, whereas when drx-InactivityTimer is inactive, this state indicates that the UE fails to decode the PDCCH in the on duration, It will enter DRX duration. When the HARQ cycle timer, i.e., the HARQ RTT timer, or the DRX retransmission timer, i.e., drx-RetransmissionTimer, is operating, the HARQ RTT timer and the drx-RetransmissionTimer are transmitted. Accordingly, a specific time instance at which the UE initiates an active state to receive an HARQ retransmission may be determined.

In state 10, the UE applies a short DRX cycle and OnDurationTimer expires, whereas when drx-InactivityTimer is inactive it indicates that the UE fails to decode the PDCCH in the on duration, It will enter DRX duration. If the HARQ RTT timer or drx-RetransmissionTimer is in operation, the HARQ RTT timer and drx-RetransmissionTimer are transmitted. Accordingly, a specific time instance at which the UE initiates an active state to receive an HARQ retransmission may be determined.

With the individual state information, the UE enters a discontinuous reception state (i.e., DRX duration) and / or ends a discontinuous reception state (i.e., DRX duration) and, for some eNBs, Active state) can be directly determined. For example, it can be known directly from state 2 or 6 that the UE enters a long DRX duration and a short DRX duration.

It can be seen from state 3 or 7 that the UE is directly entering the continuous reception state. refers to the UE's DRX configuration information for the eNB and informs the eNB that the UE has entered a discontinuous reception state (i. e., DRX duration) and / or the UE has terminated the discontinuous reception state (i. e., the DRX duration) It is possible to determine a time instance to enter a continuous receive state (i.e., active state). For example, if the on duration is started and then the UE enters the DRX duration when the OnDurationTimer expires and the parameter of the long DRX cycle obtained as a result of the interaction, , The UE enters an on duration at the end of a long DRX cycle; Otherwise, the UE can be determined to be in the continuous receive state upon receiving state 4.

In one or more of the state information, the UE enters a discontinuous reception state (i.e., a DRX duration), and / or ends a discontinuous reception state (i.e., DRX duration) and, for some eNBs, , Active state) can be directly determined or derived. This process can be performed in the algorithm design of the eNB, and the invention is intended to provide a way for one eNB to obtain the DRX state information of the UE for another eNB.

The invention proposes a coordination mechanism of DRX information between a UE, a MeNB, and a SeNB in a dual connectivity system in which one of the eNBs in the dual connectivity system determines whether the UE is in a discontinuous reception state It can be determined to perform scheduling to operate in a continuous reception state, thereby saving power by aligning the discontinuous reception state of the UE for two eNBs. In addition, dynamic power management of the UE can be enabled, thereby improving the transmission efficiency of the system.

Those of ordinary skill in the art will recognize that the above conditions are illustrative only, but are not intended to limit the scope of the invention. Those skilled in the art will appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments of the inventions may be embodied as electronic hardware, computer software, or both. Will be further recognized. For a clear representation of this interchangeability between hardware and software, the individual exemplary components, logical blocks, modules, circuits, and steps have been described above generally in terms of their functionality. The functions may be embodied as hardware or software depending on the specific application and design constraints imposed on the overall system. Those skilled in the art will appreciate that the functions described above may be practiced variously for each particular application, but such implementation decisions will not be interpreted as causing a departure from the scope of the invention.

Claims (15)

A method of coordinating DRX information of a UE in a dual connectivity system,
A. The master eNB and the auxiliary eNB obtain the DRX status information of the UE; And
B. The master eNB and the auxiliary eNB exchange DRX configuration information for the UE
Lt; / RTI >
Wherein the DRX state information indicates a DRX state of the UE with respect to one of the master eNB and the auxiliary eNB, and the DRX state indicates, for the one eNB of the master eNB and the auxiliary eNB, Entering the receiving state, and / or the UE terminating the discontinuous receiving state, and / or entering a continuous receiving state,
Step A:
If one eNB of the master eNB and the auxiliary eNB determines that the UE has entered the DRX state for the one eNB, the one eNB transmits to the eNB of the other one of the master eNB and the auxiliary eNB, Or transmitting the DRX state information of one of eNBs of the master eNB and the eNB to the other eNB.
Way. delete 2. The method of claim 1, wherein the eNB of one of the master eNB and the auxiliary eNB is based on the DRX state of the UE for the other eNB and / or the DRX configuration information of the UE for the other eNB. For the other eNB, a time instance in which the UE enters a discontinuous reception state and / or a time instance in which the UE terminates a discontinuous reception state and enters a continuous reception state, . 4. The method of claim 3, wherein the DRX state indicates that the UE enters the discontinuous reception state for the other eNB, and / or the UE terminates the discontinuous reception state and / How to enter. The method according to claim 1,
The master eNB transmits its DRX configuration information to the secondary eNB in a secondary-eNB-Addition message transmitted to the secondary eNB, and / or the master eNB transmits its DRX configuration information to the secondary eNB, receiving the DRX configuration information or DRX reconfiguration information of the secondary eNB by receiving a secondary-eNB-Cell-Modification message; And / or
When the eNB of one of the master eNB and the auxiliary eNB reconfigures its DRX configuration, the one eNB of the master eNB and the auxiliary eNB sends its reconstructed DRX configuration information and / or the DRX state of the UE Information to the master eNB and the other one of the auxiliary eNBs. A method of coordinating DRX information of a UE in a master eNB of a dual connectivity system,
A. Receiving first information indicating the DRX state of the UE for the auxiliary eNB or indicating the DRX state of the UE to the master eNB, transmitting second information, determined by the master eNB, to the auxiliary eNB Transmitting; And
B. The master eNB exchanges DRX configuration information for the UE with the auxiliary eNB
Lt; / RTI >
Wherein the DRX state indicates to the eNB of one of the master eNB and the auxiliary eNB that the UE enters a discontinuous reception state and / or the UE terminates the discontinuous reception state, and / . ≪ / RTI > 7. The method of claim 6, wherein the method further comprises:
The master eNB receiving the first information from the UE or the auxiliary eNB; or
The master eNB receiving the first information transmitted by the secondary eNB with the DRX configuration information reconstructed by the secondary eNB. 7. The method of claim 6, wherein step B:
The master eNB sending its DRX configuration information to the secondary eNB in the secondary eNB of the secondary eNB; And / or
Further comprising receiving the DRX configuration information of the secondary eNB or the DRX configuration information reconstructed by the secondary eNB by receiving the secondary-eNB-cell-modification message of the secondary eNode by the master eNB . 7. The method of claim 6, wherein when the master eNB reconfigures its DRX configuration,
The master eNB sends its reconstructed DRX configuration information to the auxiliary eNB; or
And the master eNB transmits its reconstructed DRX configuration information together with the second information to the auxiliary eNB. A method of coordinating DRX information of a UE in an auxiliary eNB of a dual connectivity system,
A. receiving third information indicating a DRX state entered by the UE for a master eNB or indicating fourth information determined by the auxiliary eNB indicating a DRX state of the UE for the auxiliary eNB, Transmitting to the master eNB; And
B. The auxiliary eNB exchanges DRX configuration information for the UE with the master eNB
Lt; / RTI >
Wherein the DRX state indicates to the eNB of one of the master eNB and the auxiliary eNB that the UE enters a discontinuous reception state and / or the UE terminates the discontinuous reception state, and / . ≪ / RTI > 11. The method of claim 10, wherein the method further comprises:
Receiving the third information from the UE or the master eNB; or
Wherein the auxiliary eNB receives the third information transmitted by the master eNB with the DRX configuration information reconstructed by the master eNB. 11. The method of claim 10, wherein step B comprises:
Receiving the DRX configuration information of the master eNB by receiving the ancillary-eNB-addition message for the ancillary eNB from the master eNB; And / or
Transmitting the DRX configuration information of the secondary eNB or the DRX configuration information reconstructed by the secondary eNB by transmitting the secondary-eNB-cell-modification message of the secondary eNB to the master eNB by the secondary eNB / RTI > 11. The method of claim 10, wherein when the secondary eNB is reconstructing its DRX configuration,
And the auxiliary eNB transmits its reconstructed DRX configuration information together with the fourth information to the master eNB. 11. The method of claim 10, wherein step B comprises:
Further comprising the supplementary eNB receiving the reconfigured DRX configuration information by the master eNB. A method for coordinating DRX information of a UE in a UE in a dual connectivity system,
When the UE enters the DRX state for the first eNB, the UE transmits first information to the second eNB indicating that the UE has entered the DRX state
Lt; / RTI >
Wherein the DRX state includes, for one eNB of the first eNB and the second eNB, the UE entering a discontinuous reception state and / or the UE terminating the discontinuous reception state and / And enters a receive state.

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