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.