US Patent 12082053 Handover in unlicensed band

A wireless device receives a radio resource control message from a base station that indicates a handover from a first cell of the first base station to a second cell of a second base station. During the handover, a DCI from the second base station is received that indicates a random access channel occasion. The random access channel occasion is determined and used to transmit a preamble to the second base station.