Generally discussed herein are systems and apparatuses arranged to perform a Time-of-Flight (ToF) or Round Trip Time measurement. The disclosure also includes techniques of making and using the systems and apparatuses. According to an example a station (STA) can be arranged to perform a Time-of-Flight (ToF) measurement, the STA can include a transceiver arranged to transmit a hard constraint indicating a time window in which the STA is unavailable for performing the ToF measurement, and receive an action frame of the ToF measurement from another STA at a time that is outside the time window.