Radio link failure handling for dual connectivity

1. An apparatus of a user equipment (UE), the apparatus comprising:

a transceiver configured to transmit and receive communications with a Master evolved Node-B (MeNB) and a Secondary evolved Node-B (SeNB) when the UE is configured with dual connectivity (DC); and

processing circuitry coupled to the transceiver, the processing circuitry configured to detect a radio link failure (RLF) for the SeNB, and upon detecting the RLF:

encode for transmission to the MeNB, a radio resource control (RRC) indication that the connection with the SeNB has experienced RLF;

suspend radio bearers for the SeNB based on the detected RLF for the SeNB;

reset a media access control (MAC) layer associated with communications with the SeNB;

release a serving cell configuration of the SeNB in response to a request from the MeNB, upon determining the connection with the SeNB has experienced the RLF, and

maintain connection with radio bearers for the MeNB in a non-DC configuration.

2. The apparatus of claim 1 , wherein the radio bearers for the SeNB include a data radio bearer (DRB).

3. The apparatus of claim 1 , wherein the radio bearers for the SeNB include a split DRB.

4. The apparatus of claim 1 , wherein the processing circuitry is configured to:

determine the connection with the SeNB has the RLF based on an expiration of an out-of-sync timer indicating lack of synchronization with the SeNB.

5. The apparatus of claim 1 , wherein the processing circuitry is configured to:

determine the connection with the SeNB has the RLF based on a random access problem indication received from a media access control (MAC) layer.

6. The apparatus of claim 1 , wherein the processing circuitry is configured to:

decode an indication from a radio link control (RLC) layer of the SeNB that a maximum number of retransmissions has been reached for a secondary cell group (SCG) of the SeNB; and

determine a connection with the SeNB has the RLF based on the decoded indication.

7. The apparatus of claim 1 , wherein the processing circuitry is configured to:

refrain from initiating a radio resource control (RRC) re-establishment procedure between the UE and the SeNB while a connection between the UE and the MeNB does not have a RLF.

8. The apparatus of claim 1 , wherein the processing circuitry is configured to:

upon detecting the RLF with the SeNB, apply one of a default physical channel configuration or a default semi-persistent scheduling configuration to maintain a connection with the MeNB.

9. The apparatus of claim 1 , wherein the processing circuitry is configured to:

reconfigure at least one radio bearer served by the SeNB in response to the request from the MeNB.

10. An apparatus of a user equipment (LT the apparatus comprising:

processing circuitry, the processing circuitry configured to:

detect a radio link failure (RIF) for a Secondary evolved Node-B (SeNB), while the UE is in a dual connectivity (DC) state with the SeNB and a Master evolved Node-B (MeNB), wherein the MeNB is associated with a Primary Cell (PCell) and the SeNB is associated with a Secondary Cell (SCell); and

upon detecting the RLF:

encode for transmission to the MeNB, a radio resource control (RRC) indication that the connection with the SeNB has experienced RLF;

suspend radio bearers for the SeNB, wherein the radio bearers for the SeNB include a data radio bearer (DRB) or a split DRB;

reset a media access control (MAC) layer associated with communications with the SeNB;

decode a Radio Resource Control reconfiguration message from the MeNB to remove the SCell from a set of cells serving the UE; and

maintain connection with radio bearers for the MeNB in a non-DC configuration.

11. The apparatus of claim 10 , wherein the processing circuitry is configured to:

determine the connection with the SeNB has the RLF based on an expiration of an out-of-sync timer indicating lack of synchronization with the SeNB.

12. The apparatus of claim 10 , wherein the processing circuitry is configured to:

determine the connection with the SeNB has the RLF based on a random access problem indication received from the MAC layer associated with communications to the SeNB.

13. The apparatus of claim 10 , wherein the processing circuitry is configured to:

decode an indication from a radio link control (RLC) layer of the SeNB that a maximum number of retransmissions has been reached for SCell of the SeNB; and

determine a connection with the SeNB has the RLF based on the decoded indication.

14. A non-transitory computer readable storage device including instructions stored thereon, which when executed by one or more processors of a User Equipment (UE), cause the UE to perform operations to:

detect a radio link failure (RLF) for a Secondary evolved Node-B (SeNB), while the UE is in a dual connectivity (DC) state with a secondary cell (SCell) of the SeNB and a primary cell (Pcell) of a Master evolved Node-B (MeNB);

encode for transmission to the MeNB, a radio resource control (RRC) indication that the connection with the SeNB has experienced RLF;

suspend radio bearers for the SeNB, wherein the radio bearers for the SeNB include a data radio bearer (DRB) or a split DRB;

reset a media access control (MAC) layer associated with communications to the SeNB;

decode a Radio Resource Control reconfiguration message from the MeNB to remove the SCell from a set of cells serving the UE, and

maintain connection with radio bearers for the MeNB in a non-DC configuration.

15. The non-transitory computer readable storage device of claim 14 , wherein the instructions further cause the UE to perform operations to:

determine the connection with the SeNB has the RLF based on an expiration of an out-of-sync timer indicating lack of synchronization with the SeNB.