Methods and systems for efficient uplink (UL) synchronization maintenance with a deactivated secondary cell group (SCG)

A wireless transmit receive unit (WTRU) comprising:

• a transceiver;
• and
• a processor operatively coupled to the transceiver;
• wherein:
• the transceiver is configured to receive, from a first node, indication information indicating an uplink (UL) configuration of one or more random access channel (RACH) preambles, including a power level for the one or more RACH preambles;
• the processor and the transceiver are configured to transmit, to a second node, the one or more RACH preambles at the received power level for the one or more RACH preambles;
• the transceiver is configured to receive, via the first node, a synchronization indication for the second node;
• the processor and the transceiver are configured to, based on the reception of the synchronization indication for the second node, wherein the synchronization indication for the second node includes timing advance (TA) information, update a UL TA towards the second node based on the TA information and restart a time value associated with the second node;
• and
• the processor and the transceiver are configured to transmit, using the updated UL TA towards the second node, one or more UL signals to the second node.