US Patent 9386490 Wireless device handover signalling

A first base station transmits, to a second base station and after making a handover decision for a wireless device, a first message. The first message comprises at least one parameter indicating the wireless device supports configuration of a plurality of cell groups. The first base station receives from the second base station a second message comprising first configuration parameters of a plurality of cells grouped into a first plurality of cell groups comprising a first cell group and a second cell group. The first base station transmits, to the wireless device, a third message comprising the first configuration parameters.