Symmetric transmit opportunity (TXOP) truncation

1. A symmetric transmit opportunity (TXOP) truncation method comprising:

receiving a first frame at a first station that truncates a TXOP around a second station that transmitted the first frame;

determining an estimated distance between the first station and the second station based on one or more characteristics of the received first frame; and

responsive to a determination that the coverage areas for both the first station and the second station do not substantially overlap, sending a second frame from the first station that truncates the TXOP around the first station.

2. The method of claim 1 , further comprising sending an acknowledgement (ACK) frame before sending the second frame.

3. The method of claim 1 , wherein the first frame is sent at a non-basic rate, and the second frame is sent at a basic rate.

4. The method of claim 1 , wherein sending the second frame comprises sending the first frame with an address of an access point (AP).

5. The method of claim 4 , wherein the address of the AP comprises an address in a BSSID field of the first frame.

6. The method of claim 1 , wherein the first frame is a CF-end frame.

7. The method of claim 1 , further comprising sending a frame that includes an indicator of an end of a TXOP.

8. The method of claim 7 , wherein the indicator is a trigger to truncate the TXOP.

9. A symmetric transmit opportunity (TXOP) truncation station comprising a processor configured to:

receive a frame that truncates a TXOP around a first station that transmitted the frame;

determine an estimated distance between the second station and the first station based on one or more characteristics of the received frame; and

responsive to a determination that the coverage areas for both the first station and second station do not substantially overlap, send a second frame from the second station that truncates the TXOP around the second station.

10. The station of claim 9 , wherein the processor is further configured to send an acknowledgement (ACK) frame before sending the second frame.

11. The station of claim 9 , wherein the first frame is sent at a non-basic rate, and the second frame is sent at a basic rate.

12. The station of claim 9 , wherein the processor is further configured to send the second frame by sending the first frame with an address of an access point (AP).

13. The station of claim 12 , wherein the address of the AP comprises an address in a BSSID field of the first frame.

14. The station of claim 9 , wherein the first frame is a CF-end frame.

15. A non-transitory, computer-readable medium having instructions stored there-on for performing a symmetric transmit opportunity (TXOP) truncation between a first station and a second station, the instructions comprising:

instructions for receiving a first frame at a first station that truncates a TXOP around a second station that transmitted the first frame;

instructions for determining an estimated distance between the first station and the second station based on one or more characteristics of the received first frame; and

instructions for sending a second frame from the first station that truncates the TXOP around the first station responsive to a determination that the coverage areas for both the first station and the second station do not substantially overlap.

16. The computer-readable medium of claim 15 , further comprising instructions for sending an acknowledgement (ACK) frame before sending the second frame.

17. The computer-readable medium of claim 15 , wherein the first frame is sent at a non-basic rate, and the second frame is sent at a basic rate.

18. The computer-readable medium of claim 15 , wherein sending the second frame comprises sending the first frame with an address of an access point (AP).

19. The computer-readable medium of claim 18 , wherein the address of the AP comprises an address in a BSSID field of the first frame.

20. The computer-readable medium of claim 15 , wherein the first frame is a CF-end frame.