Various solutions for transmission resource allocation with respect to user equipment (UE) and network apparatus in mobile communications are described. A UE may receive control information from a network apparatus. The UE may turn on a radio frequency (RF) transceiver of the UE in a part of a transmission time interval (TTI) to receive downlink data in an event that the control information indicates that the downlink data is scheduled in the TTI. The downlink data is scheduled in a part of the TTI but not in any other time interval. The time duration of the TTI may comprise 14 orthogonal frequency-division multiplexing (OFDM) symbols and the part of the TTI may be configured as a mini-slot with time duration less than 14 OFDM symbols.