Examples pertaining to network energy saving in mobile communications are described. A user equipment (UE) receives a report configuration from a network apparatus. The report configuration includes a list of sub-configurations, and each sub-configuration corresponds to an antenna port subset which indicates one or more enabled or disabled antenna ports of a plurality of antenna ports of the network apparatus. The UE then transmit a measurement report of a channel state information-reference signal (CSI-RS) based on the report configuration.