A method for a user equipment (UE) to receive physical downlink control channels (PDCCHs) is provided. The UE receives configuration information for a first control resource set that includes a number of symbols in a time domain and a number of resource blocks (RBs) in a frequency domain, configuration information indicating a first number of Nbundle,1 frequency contiguous RBs, and a PDCCH in the first control resource set in a number of frequency distributed blocks of Nbundle,1 RBs. The UE assumes that a demodulation reference signal associated with the reception of the PDCCH has a same preceding over the Nbundle,1 RBs. A method for constructing a search space to reduce a number of channel estimations that the UE performs for decoding PDCCHs, relative to conventional search spaces, is also provided.