Disclosed are techniques for accessing a shared communication medium. An aspect includes communicating over the shared communication medium in accordance with a Time Division Duplexing (TDD) frame structure defining a set of downlink subframes and a set of uplink subframes, each uplink subframe being divided into a transmission gap period, a contention-exempt period, and a contention-compliant period, performing a contention procedure for contending for access to the shared communication medium during the transmission gap period, selectively transmitting contention-compliant uplink control signals during the contention-compliant period, and transmitting one or more contention-exempt uplink control signals during the contention-exempt period. An aspect includes receiving a downlink subframe of the shared communication medium and transmitting an acknowledgment of the downlink subframe during an uplink subframe of the shared communication medium, the uplink subframe occurring at least a predetermined number of subframes and/or at least a predetermined amount of time after the downlink subframe.