Patent ID: 11012263

Abstract:
Embodiments herein provide a method implemented in a cloud radio access network (C-RAN). The method includes transmitting channel state information (CSI) reference signals to plurality of user equipments (UEs). The method includes receiving a measured downlink (DL) CSI from each UE among the plurality of UEs. The DL CSI corresponds to a plurality of antenna ports associated with a set of remote radio heads (RRHs) in cluster. Further, the method includes estimating an uplink (UL) CSI for each UE antenna port. The UL CSI is estimated using a pre-defined pilot structure received from each UE. The DL CSI or UL CSI is defined with respect to BS and UE antenna port pair. Furthermore, the method includes deriving a calibration coefficient for each antenna port based on measured DL CSI and estimated UL CSI. The calibrated DL CSI is used to precoder the data using a linear or non-linear precoder.