Conditional mobility with multi-connectivity
Systems, methods and instrumentalities are described herein with respect to the mobility and multi-connectivity of wireless transmit receive units. These devices may be configured to perform conditional handovers and/or conditional second cell group reconfigurations including primary secondary cell additions or changes. The devices may exchange information with a network while performing the conditional reconfigurations and/or conditional handovers. The devices may be configured with rules to handle concurrent handover and reconfiguration tasks.
1. A wireless transmit receive unit (WTRU), comprising:
a processor configured to:
perform one or more uplink transmissions via a master cell group (MCG) while a secondary cell group (SCG) is deactivated;
transmit an indication regarding the SCG to a base station in response to determining that data associated with the SCG is available for transmission;
receive a radio resource control (RRC) message from the base station, wherein the RRC message indicates a conditional reconfiguration of the SCG that includes a primary secondary cell (PSCell) to be applied by the WTRU and a measurement condition for application of the conditional reconfiguration;
responsive to receiving the RRC message, transmit a first message to the base station, wherein the first message indicates that the WTRU has received the RRC message;
determine that the measurement condition for application of the conditional reconfiguration is satisfied;
transmit a second message to the base station, wherein the second message indicates that the measurement condition for application of the conditional reconfiguration is satisfied;
apply the conditional reconfiguration; and
after having transmitted the second message indicating satisfaction of the measurement condition for application of the conditional reconfiguration and based on a determination that the application of the conditional reconfiguration has resulted in a failure based on a timer associated with completing the conditional reconfiguration of the SCG that includes the PSCell expiring, transmit a third message to the base station, wherein the third message indicates the failure.
2. The WTRU of claim 1 , wherein the conditional reconfiguration is associated with a primary secondary cell (PSCell) change or a PSCell addition.
3. The WTRU of claim 2 , wherein the RRC message further indicates a plurality of candidate PSCells associated with the conditional reconfiguration.
4. The WTRU of claim 1 , wherein the conditional reconfiguration is associated with an SCG addition or an SCG change.
5. The WTRU of claim 1 , wherein the base station is associated with the MCG.
6. The WTRU of claim 1 , wherein, responsive to the reception of the RRC message, the processor is further configured to monitor for the condition for application of the conditional reconfiguration.
7. The WTRU of claim 1 , wherein the processor being configured to apply the conditional reconfiguration comprises the processor being configured to initiate a random access procedure to a candidate primary secondary cell (PSCell) and wherein the second message is transmitted prior to the random access procedure.
8. The WTRU of claim 1 , wherein the condition for application of the conditional reconfiguration comprises a measurement condition for a candidate cell.
9. The WTRU of claim 1 , wherein the conditional reconfiguration is associated with a conditional handover.
10. The WTRU of claim 1 , wherein the conditional reconfiguration comprises a conditional primary secondary cell (PSCell) change and the processor is further configured to:
receive a conditional handover command from the base station; and
prioritize performance of the conditional handover command over performance of the conditional reconfiguration.
11. A method implemented by a wireless transmit receive unit (WTRU), the method comprising:
performing one or more uplink transmissions via a master cell group (MCG) while a secondary cell group (SCG) is deactivated;
transmitting an indication regarding the SCG to a base station in response to determining that data associated with the SCG is available for transmission;
receiving a radio resource control (RRC) message from the base station, wherein the RRC message indicates a conditional reconfiguration of the SCG that includes a primary secondary cell (PSCell) to be applied by the WTRU and a condition for application of the conditional reconfiguration;
responsive to receiving the RRC message, transmitting a first message to the base station, wherein the first message indicates that the WTRU has received the RRC message;
determining that the measurement condition for application of the conditional reconfiguration is satisfied;
transmitting a second message to the base station, wherein the second message indicates that the measurement condition for application of the conditional reconfiguration is satisfied;
applying the conditional reconfiguration; and
after having transmitted the second message indicating satisfaction of the measurement condition for application of the conditional reconfiguration and based on a determination that the application of the conditional reconfiguration has resulted in a failure based on a timer associated with completing the conditional reconfiguration of the SCG that includes the PSCell expiring, transmitting a third message to the base station, wherein the third message indicates the failure.
12. The method of claim 11 , wherein the conditional reconfiguration is associated with a primary secondary cell (PSCell) change or a PSCell addition.
13. The method of claim 12 , wherein the RRC message further indicates a plurality of candidate PSCells associated with the conditional reconfiguration.
14. The method of claim 11 , wherein the conditional reconfiguration is associated with an SCG addition or an SCG change.
15. The method of claim 11 , further comprising, responsive to the reception of the RRC message, monitoring for the condition for application of the conditional reconfiguration.
16. The method of claim 11 , wherein applying the conditional reconfiguration comprises initiating a random access procedure to a candidate primary secondary cell (PSCell) and wherein the second message is transmitted prior to the random access procedure.
17. The method of claim 11 , wherein the RRC message is received in a master cell group (MCG) and wherein the first message and the second message are transmitted in the MCG.
18. The method of claim 11 , wherein the condition for application of the conditional reconfiguration comprises a measurement condition for a candidate cell.
19. The method of claim 11 , wherein the conditional reconfiguration is associated with a conditional handover.
20. The method of claim 11 , wherein the conditional reconfiguration comprises a conditional primary secondary cell (PSCell) change and the method further comprises:
receiving a conditional handover command from the base station; and
prioritizing performance of the conditional handover command over performance of the conditional reconfiguration.