Type of Early Timing Advance Acquisition

A method comprising:

• receiving, by a wireless device from a base station, a radio resource control (RRC) reconfiguration message comprising a layer 1 and/or layer 2 triggered mobility (LTM) configuration of the wireless device, wherein the LTM configuration comprises:
• a configuration of a candidate cell for an LTM;
• a first identifier of the candidate cell;
• and
• a second identifier of the candidate cell for an early timing advance acquisition (ETA), wherein the ETA comprises a user equipment (UE) based timing advance (TA) measurement;
• measuring a TA value of the candidate cell based on the RRC reconfiguration message comprising the second identifier;
• receiving an LTM cell switch command indicating the candidate cell;
• and
• in response to receiving the LTM cell switch command, transmitting, via the candidate cell and based on the TA value, an uplink packet.

A base station central unit comprising:

• one or more processors;
• and
• memory storing instructions that, when executed by the one or more processors, cause the base station central unit to:
• receive, from a wireless device via a first base station distributed unit, a measurement report;
• after receiving the measurement report, transmit, to a second base station distributed unit of a candidate cell, a user equipment (UE) context setup request message, for the wireless device, wherein the UE context setup request message comprises a first identifier of the candidate cell for a layer 1 and/or layer 2 triggered mobility (LTM);
• receive, from the second base station distributed unit, a UE context setup response message, for the wireless device, comprising a lower layer configuration of the candidate cell;
• and
• transmit, to the first base station distributed unit, a UE context modification request message, for the wireless device, comprising:
• the first identifier of the candidate cell for the LTM;
• and
• a second identifier of the candidate cell for early timing advance acquisition (ETA),
• wherein the ETA comprises a user equipment (UE) based timing advance (TA) measurement.