Tone Plan for Ltf Compression

1. A method of operating a wireless device, comprising: transmitting user data in a plurality of first symbols, wherein each first symbol of the plurality of first symbols is a data symbol, wherein each first symbol of the plurality of first symbols has a first symbol duration, a first frequency bandwidth, and a first tone plan, wherein the first tone plan comprises a first valid start tone index, a first valid end tone index, and a first set of direct current (DC) tones; and transmitting a long training field (LTF) in a plurality of second symbols, wherein each second symbol of the plurality of second symbols is an LTF symbol, wherein each second symbol of the plurality of second symbols has a second symbol duration that is less than the first symbol duration, a second frequency bandwidth, and a second tone plan, wherein the second tone plan comprises a second valid start tone index, a second valid end tone index, and a second set of DC tones, wherein the second valid start tone index is a function of the first valid start tone index, the second valid end tone index is a function of the first valid end tone index, and the first symbol duration is two times greater than the second symbol duration, and wherein at least one of: (i) the first and second frequency bandwidths are 20 megahertz, the first valid start tone index is −122, the first valid end tone index is 122, the second valid start tone index is −61, and the second valid end tone index is 61, ii) the first and second frequency bandwidths are 40 megahertz, the first valid start tone index is −250, the first valid end tone index is 250, the second valid start tone index is −125, and the second valid end tone index is 125, or (iii) the first and second frequency bandwidths are 80 megahertz, the first valid start tone index is −506, the first valid end tone index is 506, the second valid start index is −253, and the second valid end tone index is 253.

2. The method of claim 1, further comprising: determining the first tone plan associated with the plurality of first symbols based on configuration information; and determining the second tone plan associated with the plurality of second symbols based on the configuration information.

3. The method of claim 1, wherein the second valid start tone index is a function of the first valid start tone index, and the second valid end tone index is a function of the first valid end tone index.

4. The method of claim 1, wherein the first set of DC tones includes three DC tones located at tone indices −1, 0, and 1, and wherein the second set of DC tones includes one DC tone located at tone index 0.

5. The method of claim 1, wherein the first set of DC tones includes eleven DC tones located at tone indices −5, −4, −3, −2, −1, 0, 1, 2, 3, 4, and 5, and wherein the second set of DC tones includes three DC tones located at tone indices −1, 0, and 1 or one DC tone located at tone index 0.

6. The method of claim 1, wherein the first set of DC tones includes seven DC tones located at tone indices −3, −2, −1, 0, 1, 2, and 3, and wherein the second set of DC tones includes three DC tones located at tone indices −1, 0, and 1 or one DC tone at tone index 0.

7. The method of claim 1, wherein the first set of DC tones includes three DC tones located at tone indices −1, 0, and 1, and wherein the second set of DC tones includes three DC tones located at tone indices −1, 0, and 1.

8. The method of claim 1, wherein the first set of DC tones includes eleven DC tones located at tone indices −5, −4, −3, −2, −1, 0, 1, 2, 3, 4, and 5, and wherein the second set of DC tones includes five DC tones located at tone indices −2, −1, 0, 1, and 2 or three DC tones located at tone indices −1, 0, and 1.

9. The method of claim 1, wherein the first set of DC tones includes seven DC tones located at tone indices −3, −2, −1, 0, 1, 2, and 3, and wherein the second set of DC tones includes five DC tones located at tone indices −2, −1, 0, 1, and 2 or three DC tones located at tone indices −1, 0, and 1.

10. The method of claim 1, wherein the first symbol duration is two times greater than the second symbol duration, the first and second frequency bandwidths are 20 megahertz, the first valid start tone index is −122, the first valid end tone index is 122, the second valid start tone index is −61, and the second valid end tone index is 61.

11. The method of claim 1, wherein the first symbol duration is two times greater than the second symbol duration, the first and second frequency bandwidths are 40 megahertz, the first valid start tone index is −250, the first valid end tone index is 250, the second valid start tone index is −125, and the second valid end tone index is 125.

12. The method of claim 1, wherein the first symbol duration is two times greater than the second symbol duration, the first and second frequency bandwidths are 80 megahertz, the first valid start tone index is −506, the first valid end tone index is 506, the second valid start tone index is −253, and the second valid end tone index is 253.

13. The method of claim 1, wherein the DC tones have zero amplitude and non-DC tones include guard tones, data tones, and pilot tones, wherein the guard tone tones have zero amplitude, the data tones include data to be transmitted, and pilot tones include known information for channel estimation.

14. The method of claim 1, wherein a plurality of tones within each respective LTF symbol is grouped according to a group number to reduce LTF symbol overhead.

15. The method of claim 1, wherein the second symbol duration and information within each respective LTF symbol are compressed to reduce LTF symbol overhead.

16. The method of claim 15, wherein the second valid start tone index and the second valid end tone index of each respective LTF symbol are compressed based on at least one of: a third valid start tone index or a third valid end tone index.

17. The method of claim 1, wherein transmitting the LTF in the plurality of second symbols includes transmitting the LTF in an upshifted subset of tone indices associated with the plurality of second symbols.

18. The method of claim 1, wherein transmitting the LTF in the plurality of second symbols includes transmitting the LTF in a downshifted subset of tone indices associated with the plurality of second symbols.

19. An apparatus for wireless communication, comprising: means for transmitting user data in a plurality of first symbols, wherein each first symbol of the plurality of first symbols is a data symbol, wherein each first symbol of the plurality of first symbols has a first symbol duration, a first frequency bandwidth, and a first tone plan, wherein the first tone plan comprises a first valid start tone index, a first valid end tone index, and a first set of direct current (DC) tones; and means for transmitting a long training field (LTF) in a plurality of second symbols, wherein each second symbol of the plurality of second symbols is an LTF symbol, wherein each second symbol of the plurality of second symbols has a second symbol duration that is less than the first symbol duration, a second frequency bandwidth, and a second tone plan, wherein the second tone plan comprises a second valid start tone index, a second valid end tone index, and a second set of DC tones, wherein the second valid start tone index is a function of the first valid start tone index, the second valid end tone index is a function of the first valid end tone index, and the first symbol duration is two times greater than the second symbol duration, and wherein at least one of: (i) the first and second frequency bandwidths are 20 megahertz, the first valid start tone index is −122, the first valid end tone index is 122, the second valid start tone index is −61, and the second valid end tone index is 61, (ii) the first and second frequency bandwidths are 40 megahertz, the first valid start tone index is −250, the first valid end tone index is 250, the second valid start tone index is −125, and the second valid end tone index is 125, or (iii) the first and second frequency bandwidths are 80 megahertz, the first valid start tone index is −506, the first valid end tone index is 506, the second valid start tone index is −253, and the second valid end tone index is 253.

20. The apparatus of claim 19, wherein the second valid start tone index is a function of the first valid start tone index, and the second valid end tone index is a function of the first valid end tone index.

21. An apparatus for wireless communication, comprising: a memory; and at least one processor coupled to the memory, wherein the at least one processor is configured to: transmit user data in a plurality of first symbols, wherein each first symbol of the plurality of first symbols is a data symbol, wherein each first symbol of the plurality of first symbols has a first symbol duration, a first frequency bandwidth, and a first tone plan, wherein the first tone plan comprises a first valid start tone index, a first valid end tone index, and a first set of direct current (DC) tones; and transmit a long training field (LTF) in a plurality of second symbols, wherein each second symbol of the plurality of second symbols is an LTF symbol, wherein each second symbol of the plurality of second symbols has a second symbol duration that is less than the first symbol duration, a second frequency bandwidth, and a second tone plan, wherein the second tone plan comprises a second valid start tone index, a second valid end tone index, and a second set of DC tones, wherein the second valid start tone index is a function of the first valid start tone index, the second valid end tone index is a function of the first valid end tone index, and the first symbol duration is two times greater than the second symbol duration: and wherein at least one of: (i) the first and second frequency bandwidths are 20 megahertz, the first valid start tone index is −122, the first valid end tone index is 122, the second valid start tone index is −61, and the second valid end tone index is 61, (ii) the first and second frequency bandwidths are 40 megahertz, the first valid start tone index is −250, the first valid end tone index is 250, the second valid start tone index is −125, and the second valid end tone index is 125, or (iii) the first and second frequency bandwidths are 80 megahertz, the first valid start tone index is −506, the first valid end tone index is 506, the second valid start tone index is −253, and the second valid end tone index is 253.

22. The apparatus of claim 21, wherein the at least one processor is further configured to: determine the first tone plan associated with the plurality of first symbols based on configuration information; and determine the second tone plan associated with the plurality of second symbols based on the configuration information.

23. The apparatus of claim 21, wherein the second valid start tone index is a function of the first valid start tone index, and the second valid end tone index is a function of the first valid end tone index.

24. The apparatus of claim 21, wherein the first set of DC tones includes three DC tones located at tone indices −1, 0, and 1, and wherein the second set of DC tones includes one DC tone located at tone index 0.

25. The apparatus of claim 21, wherein the first set of DC tones includes eleven DC tones located at tone indices −5, −4, −3, −2, −1, 0, 1, 2, 3, 4, and 5, and wherein the second set of DC tones includes three DC tones located at tone indices −1, 0, and 1 or one DC tone located at tone index 0.

26. The apparatus of claim 21, wherein the first set of DC tones includes seven DC tones located at tone indices −3, −2, −1, 0, 1, 2, and 3, and wherein the second set of DC tones includes three DC tones located at tone indices −1, 0, and 1 or one DC tone at tone index 0.

27. The apparatus of claim 21, wherein the first set of DC tones includes three DC tones located at tone indices −1, 0, and 1, and wherein the second set of DC tones includes three DC tones located at tone indices −1, 0, and 1.

28. The apparatus of claim 21, wherein the first set of DC tones includes eleven DC tones located at tone indices −5, −4, −3, −2, −1, 0, 1, 2, 3, 4, and 5, and wherein the second set of DC tones includes five DC tones located at tone indices −2, −1, 0, 1, and 2 or three DC tones located at tone indices −1, 0, and 1.

29. The apparatus of claim 21, wherein the first set of DC tones includes seven DC tones located at tone indices −3, −2, −1, 0, 1, 2, and 3, and wherein the second set of DC tones includes five DC tones located at tone indices −2, −1, 0, 1, and 2 or three DC tones located at tone indices −1, 0, and 1.

30. The apparatus of claim 21, wherein the first symbol duration is two times greater than the second symbol duration, the first and second frequency bandwidths are 20 megahertz, the first valid start tone index is −122, the first valid end tone index is 122, the second valid start tone index is −61, and the second valid end tone index is 61.

31. The apparatus of claim 21, wherein the first symbol duration is two times greater than the second symbol duration, the first and second frequency bandwidths are 40 megahertz, the first valid start tone index is −250, the first valid end tone index is 250, the second valid start tone index is −125, and the second valid end tone index is 125.

32. The apparatus of claim 21, wherein the first symbol duration is two times greater than the second symbol duration, the first and second frequency bandwidths are 80 megahertz, the first valid start tone index is −506, the first valid end tone index is 506, the second valid start tone index is −253, and the second valid end tone index is 253.

33. A non-transitory computer-readable medium having code stored thereon that, when executed, causes at least one processor of a wireless device to: transmit user data in a plurality of first symbols, wherein each first symbol of the plurality of first symbols is a data symbol, wherein each first symbol of the plurality of first symbols has a first symbol duration, a first frequency bandwidth, and a first tone plan, wherein the first tone plan comprises a first valid start tone index, a first valid end tone index, and a first set of direct current (DC) tones; and transmit a long training field (LTF) in a plurality of second symbols, wherein each second symbol of the plurality of second symbols is an LTF symbol, wherein each second symbol of the plurality of second symbols has a second symbol duration that is less than the first symbol duration, a second frequency bandwidth, and a second tone plan, wherein the second tone plan comprises a second valid start tone index, a second valid end tone index, and a second set of DC tones, wherein the second valid start tone index is a function of the first valid start tone index, the second valid end tone index is a function of the first valid end tone index, and the first symbol duration is two times greater than the second symbol duration, and wherein at least one of: (i) the first and second frequency bandwidths are 20 megahertz, the first valid start tone index is −122, the first valid end tone index is 122, the second valid start tone index is −61, and the second valid end tone index is 61, (ii) the first and second frequency bandwidths are 40 megahertz, the first valid start tone index is −250, the first valid end tone index is 250, the second valid start tone index is −125, and the second valid end tone index is 125, or (iii) the first and second frequency bandwidths are 80 megahertz, the first valid start tone index is −506, the first valid end tone index is 506, the second valid start tone index is −253, and the second valid end tone index is 253.