Methods and systems for providing efficient operation of multiple modes in a wlan system

An access point (AP) comprising:

• a receiver configured to receive a request-to-send (RTS) frame from a station (STA), wherein the RTS frame indicates a request for a transmit opportunity (TXOP);
• and
• a transmitter configured to transmit, in response to the RTS frame, an indication of a TXOP, wherein the indication of a TXOP is a space-time block code (STBC) clear-to-send (CTS) frame and a non-STBC CTS frame;
• wherein the receiver is further configured to receive packet data from the STA during the TXOP, and receive, on a condition that the STA does not have further packet data to transmit, an indication of truncation of the TXOP including a first STBC contention free (CF)-End frame or a first non-STBC CF-End frame;
• and
• wherein the transmitter is further configured to transmit a second STBC CF-End frame and a second non-STBC CF-End frame.