Downlink pre-synchronization for time alignment establishment on ltm candidate cells

A method performed by a network node in a wireless communication network for L1/L2 based inter-cell mobility, LTM, of a user equipment, UE, to a candidate cell, the method comprising:

• transmitting to the UE an LTM configuration including an LTM candidate cell configuration for TA establishment and/or TA update with the LTM candidate cell;
• transmitting an indication to the UE to perform downlink, DL, pre-synchronization to the LTM candidate cell;
• and
• transmitting a trigger to the UE for TA establishment and/or TA update to the LTM candidate cell, wherein the indication is transmitted in a medium access control, MAC, control element, CE, after transmission of the LTM configuration.

A user equipment, UE, in a wireless communication network, configured to:

• receive an LTM configuration including an LTM candidate cell configuration for TA establishment and/or TA update with the LTM candidate cell;
• receive an indication to perform downlink, DL, pre-synchronization with the LTM candidate cell;
• perform DL pre-synchronization with the LTM candidate cell in response to the indication;
• after said DL pre-synchronization with the LTM candidate cell, receive, from a serving cell, a trigger for TA establishment and/or TA update to the LTM candidate cell;
• and
• transmit, in response to the trigger, an uplink, UL, signal to the LTM candidate cell for TA establishment and/or update,
• wherein the UE receives the indication in a medium access control, MAC, control element, CE, after receipt of the LTM configuration.

A network node in a wireless communication network configured to:

• transmit to the UE an LTM configuration including an LTM candidate cell configuration for TA establishment and/or TA update with the LTM candidate cell;
• transmit an indication to the UE to perform downlink, DL, pre-synchronization to the LTM candidate cell;
• and
• transmit a trigger to the UE for TA establishment and/or TA update to the LTM candidate cell,
• wherein the network node transmits the indication in a medium access control, MAC, control element, CE, after transmission of the LTM configuration.