This disclosure relates to methods for transmitting and receiving multi-user request-to-send and clear-to-send frames in a wireless communication system. An access point wireless device may establish wireless connections with multiple wireless devices. The access point wireless device may transmit a multi-user request-to-send frame to the wireless devices. The multi-user request-to-send frame may indicate a transmit opportunity duration and allocate frequency resource units on which to transmit clear-to-send frames to the wireless devices. The wireless devices may transmit the clear-to-send frames on the allocated frequency resource units. The clear-to-send frames can include an indication of partial or full availability for the transmit opportunity.