A method for an ePDCCH performed by a WTRU, a WTRU, a search space monitoring method, and a UE may be provided. The method comprises that the WTRU receives a configuration, the configuration defining a plurality of ePDCCH resource sets for monitoring ePDCCHs, each ePDCCH resource set being associated with a respective scrambling sequence, the configuration indicating demodulation timing reference information for each ePDCCH resource set; the WTRU monitors at least one search space associated with each ePDCCH resource set, wherein each ePDCCH resource set is associated with a demodulation reference signal (DM-RS), and the demodulation reference signal (DM-RS) is associated with the scrambling sequence configured for the ePDCCH resource set; and the WTRU receives at least one ePDCCH transmission via at least one of the set of ePDCCH resources.