US Patent 9455775 Handover signaling for beamforming communications

A first base station receives a first message comprising one or more parameters indicating whether a wireless device supports configuration of a number of channel state information (CSI) processes. The first base station transmits at least one second message comprising configuration parameters of CSI reference signals. The first base station transmits, to a second base station after making a handover decision, at least one third message comprising at least one of the one or more parameters and the configuration parameters of the CSI reference signals.