A method of downlink control information (DCI) transmission is proposed to enhance DCI transmission efficiency over physical layer signaling in cellular mobile communication networks. A serving base station uses a higher layer signaling, e.g., radio resource control (RRC) signaling message to configure a plurality of user equipments (UEs) to monitor UE-group DCI. When the UE is configured to monitor UE-group DCI, the UE monitors both unicast DCI and UE-group DCI in each corresponding scheduling time unit, e.g., a subframe in LTE. The candidate positions of the unicast DCI and the UE-group DCI can be orthogonal, partially overlapping, or fully overlapping with each other.