Support for additional decoding processing time in wireless LAN systems

1. A method of a communication device in a wireless system, the method comprising:

generating a first High Efficiency Physical Layer Protocol Data Unit (HE PPDU) including a Non-High-Throughput (Non-HT) signal (L-SIG) field, a High Efficiency signal (HE-SIG) field, and a data field, wherein the data field includes an Orthogonal Frequency Division Multiplexing (OFDM) symbol including padding bits;

appending an extension at an end of the first HE PPDU to increase an available processing time, the extension having a non-zero signal strength; and

transmitting a second HE PPDU including the first HE PPDU and the extension,

wherein the L-SIG field includes a first length indication of the second HE PPDU, and

wherein the HE-SIG field includes a second length indication for a duration of the extension to avoid ambiguity of the extension.

2. The method of claim 1 , wherein the second length indication indicates whether the duration of the extension is greater than a reference duration.

3. The method of claim 1 , wherein the extension supports plural durations which are a multiple of a unit of time.

4. The method of claim 3 , wherein the unit of time is 4 microseconds.

5. The method of claim 4 , wherein the plural durations include 0, 4, 8, 12, and 16 microseconds.

6. The method of claim 1 , wherein the L-SIG field indicates an end of the extension.

7. The method of claim 6 , wherein the L-SIG field includes an L-SIG length field indicating the end of the extension.

8. The method of claim 1 , wherein the padding bits are appended after an encoding stage encoding a MAC frame.

9. The method of claim 1 , wherein the OFDM symbol has a symbol duration of 12.8 microsecond excluding a cyclic prefix.

10. The method of claim 9 , wherein the OFDM symbol supports plural cyclic prefix durations of 0.8, 1.6, and 3.2 microseconds.

11. A method of a first communication device in a wireless system, the method comprising:

receiving a first High Efficiency Physical Layer Protocol Data Unit (HE PPDU) including a second HE PPDU including a Non-High-Throughput (Non-HT) signal (L-SIG) field, a High Efficiency signal (HE-SIG) field, and a data field, wherein the data field includes an Orthogonal Frequency Division Multiplexing (OFDM) symbol including padding bits, and the first HE PPDU further includes an extension appended at an end of the second HE PPDU to increase an available processing time, the extension having a non-zero signal strength; and

transmitting an Acknowledgement frame a predetermined inter-frame space after the end of the first HE PPDU,

wherein the L-SIG field includes a first length indication of the first HE PPDU,

wherein the HE-SIG field includes a second length indication for a duration of the extension to avoid ambiguity of the extension.

12. The method of claim 11 , wherein the second length indication indicates whether the duration of the extension is greater than a reference duration.

13. The method of claim 11 , wherein the extension supports plural durations which are a multiple of a unit of time.

14. The method of claim 13 , wherein the unit of time is 4 microseconds.

15. The method of claim 11 , wherein the plural durations include 0, 4, 8, 12, and 16 microseconds.

16. The method of claim 11 , wherein the L-SIG field includes a L-SIG length field indicating an end of the extension.

17. The method of claim 11 , wherein the OFDM symbol has a symbol duration of 12.8 microsecond excluding a cyclic prefix, and supports plural cyclic prefix durations of 0.8, 1.6, and 3.2 microseconds.

18. The method of claim 11 , wherein the predetermined inter-frame space is 16 microseconds.