Efficient use of physical and logical resources in dual connectivity

1 . A method for managing resources associated with a user equipment (UE) operating in dual connectivity (DC) with a master node (MN) and a secondary node (SN) in accordance with an initial configuration of a radio connection between the UE and a radio access network (RAN), the method implemented in the MN and comprising:

detecting that traffic of the UE is inactive on a radio bearer via which the UE communicates with the SN;

in response to the detecting, sending, from the MN to the SN, a request to release lower layers of the radio bearer, the lower layers including a PHY layer and a MAC layer;

receiving, at the MN from the SN, an acknowledgement message, including omitting from the acknowledgement message a radio resource control (RRC) message with a reconfiguration for the radio connection; and

in response to the detecting, sending to the UE a command to transition from a connected state to an inactive state in which the radio connection is suspended,

while the UE operates in accordance with the initial configuration of the radio connection.

2 . The method of claim 1 , further comprising:

not sending to the UE a reconfiguration for the radio connection, after detecting that the UE is inactive on the radio bearer and prior to sending the command to UE.

3 . The method of claim 1 , further comprising:

resuming the suspended radio connection subsequently to sending the command to transition from the connected state to the inactive state; and

providing lower layers for the radio bearer, to enable the UE to communicate with the SN over the radio bearer via the MN.

4 . The method of claim 1 , wherein the sending the request to release lower layers of the radio bearer occurs prior to the sending the command to the UE.

5 . The method of claim 1 , wherein the sending the request to release lower layers of the radio bearer occurs after the sending the command to the UE.

6 . The method of claim 1 , wherein configuring the radio bearer to be terminated only at the MN includes:

prior to sending the command, sending, from the MN to the UE, an RRC reconfiguration message.

7 . The method of claim 6 , wherein configuring the radio bearer to be terminated only at the MN includes:

receiving, by the MN from the SN, an activity notification indicating that the UE is inactive on the radio bearer, and

determining, at the MN, to reconfigure the radio bearer in response to the activity notification.

8 . The method of claim 7 , further comprising, in response to the determining to reconfigure the radio bearer:

sending, from the MN to the SN, a request to reconfigure the radio bearer.

9 . The method of claim 7 , wherein configuring the radio bearer to be terminated only at the MN includes:

receiving, at the MN from the SN, an indication that a release of the SN is required, and

determining, at the MN, to reconfigure the radio bearer in response to the indication.

10 . The method of claim 7 , wherein configuring the radio bearer to be terminated only at the MN includes:

receiving, at the MN from the SN, an indication that a reconfiguration of the radio bearer is required, and

determining, at the MN, to reconfigure the radio bearer in response to the indication.

11 . The method of claim 10 , further comprising, in response to the determining to reconfigure the radio bearer:

sending, from the MN to the SN, an indication that the MN has accepted the requirement of the reconfiguration of the radio bearer.

12 . A

base station operating as a master node (MN) in dual connectivity (DC) communication with a user equipment (UE), with

a second base station operating as a secondary node (SN) in the DC communication with the UE;

the MN configured to:

detect that traffic of the UE is inactive on a radio bearer via which the UE communicates with the SN,

in response to the detecting, send, from the MN to the SN, a request to release lower layers of the radio bearer, the lower layers including a PHY layer and a MAC layer,

receive, at the MN from the SN, an acknowledgement message, including omitting from the acknowledgement message a radio resource control (RRC) message with a reconfiguration for the radio connection,

in response to the detecting, send to the UE, while the UE operates in accordance with the initial configuration of the radio connection, a command to transition from a connected state to an inactive state in which the radio connection is suspended.

13 . The MN of claim 12 , further configured to:

not send to the UE a reconfiguration for the radio connection, after detecting that the UE is inactive on the radio bearer and prior to sending the command to UE.

14 . The MN of claim 12 , further configured to:

resume the suspended radio connection subsequently to sending the command to transition from the connected state to the inactive state, and

provide lower layers for the radio bearer, to enable the UE to communicate with the SN over the radio bearer via the MN.

15 . The MN of claim 12 , wherein sending the request to release lower layers of the radio bearer occurs prior to the sending the command to the UE.

16 . The MN of claim 12 , wherein the sending the request to release lower layers of the radio bearer occurs after the sending the command to the UE.

17 . The MN of claim 12 , wherein to configure the radio bearer to be terminated only at the MN, the RAN is configured to:

prior to sending the command, send, from the MN to the UE, an RRC reconfiguration message.

18 . The MN of claim 17 , wherein to configure the radio bearer to be terminated only at the MN, the RAN is configured to:

receive, by the MN from the SN, an activity notification indicating that the UE is inactive on the radio bearer, and

determine, at the MN, to reconfigure the radio bearer in response to the activity notification.

19 . The MN of claim 17 , further configured to:

in response to the determining to reconfigure the radio bearer:

send, from the MN to the SN, a request to reconfigure the radio bearer.

20 . The MN of claim 17 , wherein to configure the radio bearer to be terminated only at the MN, the MN is configured to:

receive, at the MN from the SN, an indication that a release of the SN is required, and

determine, at the MN, to reconfigure the radio bearer in response to the indication.