A first communication device generates and transmits a frame that is configured to cause one or more second communication devices in a wireless local area network (WLAN) to refrain from transmitting during a set of repeating time segments, and the frame is generated to include an indication of a time period of the time segments in the set of repeating time segments, the time period being less than a duration of a beacon interval of the WLAN such that multiple ones of the time segments occur within one beacon interval. Alternatively, the frame is configured to cause one or more second communication devices in the WLAN to refrain from transmitting during a time segment that begins in conjunction with an end of transmission of i) the frame or ii) a packet that includes the frame, and the frame is generated to include an indication of a time duration of the time segment.