US Patent 10499300 Handover signalling in wireless networks

A serving base station receives a first message comprising at least one parameter indicating whether a wireless device supports configuration of timing advance groups (TAGs). The serving base station transmits a second message causing assignment of each of at least one secondary cell to a TAG in a first plurality of TAGs. The serving base station transmits a third message to a target base station. The third message comprises at least one of: the at least one parameter indicating whether the wireless device supports configuration of the plurality of TAGs; and configuration information of the first plurality of TAGs.