A first communication device receives an indication that a second communication device permits a duplex transmission while the second communication device transmits during a transmit opportunity period (TXOP), where duplex transmissions involve simultaneously transmitting and receiving via a same wireless frequency band. The indication is included in a media access control layer (MAC) protocol data unit (MPDU). In response to receiving the indication that the second communication device permits the duplex transmission, the first communication device determines that the first communication device is permitted to perform the duplex transmission during the TXOP. The first communication device receives a first packet from the second communication device during the TXOP, and transmits a second packet while the first communication device is receiving the first packet.