Methods, apparatuses, systems, and devices are described for wireless communication. In one method, a control format indicator value for a frame may be received over a physical carrier in a shared spectrum. Based on the control format indicator value, a number of subframes of the frame to be used by a base station for downlink transmissions over the physical carrier may be determined. The control format indicator value may indicate an end of transmission, if data is to be transmitted during the frame, a number of subframes to be used for transmission, or whether the current subframe is the final subframe used for transmission. In some cases, a user equipment (UE) may use the control format indicator value to determine a sleep schedule. Further, ACK/NACK transmissions by a UE may be scheduled based on the control format indicator value.