METHOD AND APPARATUS FOR CONSTRUCTING VERY HIGH THROUGHPUT SHORT TRAINING FIELD SEQUENCES

• US 20110194545A1
• Filed: 03/17/2011
• Published: 08/11/2011
• Est. Priority Date: 07/17/2009
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Sampath, Hemanth, Yang, Lin, Van Nee, Didier Johannes Richard
• Granted Patent: US 8,717,865 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 27/2614 Peak power aspects
• CPC Class Codes: H04L 27/262 Reduction thereof by selection of pilot symbols
• CPC Class Codes: H04L 27/2621 Reduction thereof using phase offsets between subcarriers
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 5/0023 Time-frequency-space

Abstract

Certain aspects of the present disclosure relate to a technique for constructing a short training field (STF) sequence of a Very High Throughput (VHT) preamble in an effort to reduce a peak-to-average power ratio (PAPR). The constructed STF sequence may feature a specific repetition period.

Claims

1. A method for wireless communications, comprising:

constructing a short training field (STF) sequence with a repetition period by using STF symbol values associated with the IEEE 802.11n standard, wherein

the STF symbol values cover at least a portion of bandwidth of a first size, and

each of the STF symbol values is repeated one or more times for different subcarriers;

rotating phases of symbols of the STF sequence per bandwidth of the first size in an effort to reduce a peak-to-average power ratio (PAPR) during transmission of the STF sequence; and

transmitting the STF sequence over a wireless channel by utilizing a bandwidth of a second size.

2. The method of claim 1, wherein the bandwidth of first size comprises a bandwidth of 20 MHz or a bandwidth of 40 MHz.

3. The method of claim 1, further comprising:

rotating phases of a plurality of symbols of the STF sequence in an effort to reduce the PAPR, wherein the plurality of symbols is in a portion of the bandwidth of the second size.

4. The method of claim 1, further comprising:

performing oversampling before the transmission.

5. The method of claim 1, wherein the bandwidth of second size comprises a bandwidth of 80 MHz.

6. The method of claim 1, wherein the repetition period comprises 800 ns.

7. The method of claim 1, further comprising:

multiplying the constructed STF sequence with a plurality of orthogonal sequences of symbols to obtain a plurality of modified STF sequences; and

transmitting each of the modified STF sequences in a different spatial stream.

8. The method of claim 1, further comprising:

applying cyclic delay on the constructed STF sequence using a plurality of cyclic delays equal to multiples of a defined period to obtain a plurality of cyclically delayed STF sequences; and

transmitting each of the cyclically delayed STF sequences in a different spatial stream of a plurality of spatial streams.

9. The method of claim 8, wherein:

the defined period comprises 50 ns, and

the plurality of spatial streams comprises eight spatial streams.

10. The method of claim 1, wherein each of the STF symbol values is repeated one time for different subcarriers.

11. The method of claim 1, wherein each of the STF symbol values is repeated three times for different subcarriers.

12. An apparatus for wireless communications, comprising:

a first circuit configured to construct a short training field (STF) sequence with a repetition period by using STF symbol values associated with the IEEE 802.11n standard, wherein

the STF symbol values cover at least a portion of bandwidth of a first size, and

each of the STF symbol values is repeated one or more times for different subcarriers;

a second circuit configured to rotate phases of symbols of the STF sequence per bandwidth of the first size in an effort to reduce a peak-to-average power ratio (PAPR) during transmitting the STF sequence; and

a transmitter configured to transmit the STF sequence over a wireless channel by utilizing a bandwidth of a second size.

13. The apparatus of claim 12, wherein the bandwidth of first size comprises a bandwidth of 20 MHz or a bandwidth of 40 MHz.

14. The apparatus of claim 12, wherein the second circuit is also configured to:

rotate phases of a plurality of symbols of the STF sequence in an effort to reduce the PAPR, wherein the plurality of symbols is in a portion of the bandwidth of the second size.

15. The apparatus of claim 12, further comprising:

a third circuit configured to perform oversampling before the transmission.

16. The apparatus of claim 12, wherein the bandwidth of second size comprises a bandwidth of 80 MHz.

17. The apparatus of claim 12, wherein the repetition period comprises 800 ns.

18. The apparatus of claim 12, further comprising:

a third circuit configured to multiply the constructed STF sequence with a plurality of orthogonal sequences of symbols to obtain a plurality of modified STF sequences, and wherein the transmitter is also configured to transmit each of the modified STF sequences in a different spatial stream.

19. The apparatus of claim 12, further comprising:

a third circuit configured to apply cyclic delay on the constructed STF sequence using a plurality of cyclic delays equal to multiples of a defined period to obtain a plurality of cyclically delayed STF sequences, and wherein the transmitter is also configured to

transmit each of the cyclically delayed STF sequences in a different spatial stream of a plurality of spatial streams.

20. The apparatus of claim 19, wherein:

the defined period comprises 50 ns, and

the plurality of spatial streams comprises eight spatial streams.

21. The apparatus of claim 12, wherein each of the STF symbol values is repeated one time for different subcarriers.

22. The apparatus of claim 12, wherein each of the STF symbol values is repeated three times for different subcarriers.

23. An apparatus for wireless communications, comprising:

means for constructing a short training field (STF) sequence with a repetition period by using STF symbol values associated with the IEEE 802.11n standard, wherein

the STF symbol values cover at least a portion of bandwidth of a first size, and

each of the STF symbol values is repeated one or more times for different subcarriers;

means for rotating phases of symbols of the STF sequence per bandwidth of the first size in an effort to reduce a peak-to-average power ratio (PAPR) during transmission of the STF sequence; and

means for transmitting the STF sequence over a wireless channel by utilizing a bandwidth of a second size.

24. The apparatus of claim 23, wherein the bandwidth of first size comprises a bandwidth of 20 MHz or a bandwidth of 40 MHz.

25. The apparatus of claim 23, further comprising:

means for rotating phases of a plurality of symbols of the STF sequence in an effort to reduce the PAPR, wherein the plurality of symbols is in a portion of the bandwidth of the second size.

26. The apparatus of claim 23, further comprising:

means for performing oversampling before the transmission.

27. The apparatus of claim 23, wherein the bandwidth of second size comprises a bandwidth of 80 MHz.

28. The apparatus of claim 23, wherein the repetition period comprises 800 ns.

29. The apparatus of claim 23, further comprising:

means for multiplying the constructed STF sequence with a plurality of orthogonal sequences of symbols to obtain a plurality of modified STF sequences, wherein the means for transmitting is further configured to

transmit each of the modified STF sequences in a different spatial stream.

30. The apparatus of claim 23, further comprising:

means for applying cyclic delay on the constructed STF sequence using a plurality of cyclic delays equal to multiples of a defined period to obtain a plurality of cyclically delayed STF sequences, wherein the means for transmitting is further configured to

transmit each of the cyclically delayed STF sequences in a different spatial stream of a plurality of spatial streams.

31. The apparatus of claim 30, wherein:

the defined period comprises 50 ns, and

the plurality of spatial streams comprises eight spatial streams.

32. The apparatus of claim 23, wherein each of the STF symbol values is repeated one time for different subcarriers.

33. The apparatus of claim 23, wherein each of the STF symbol values is repeated three times for different subcarriers.

34. A computer-program product for wireless communications, comprising a computer-readable medium comprising instructions executable to:

construct a short training field (STF) sequence with a repetition period by using STF symbol values associated with the IEEE 802.11n standard, wherein

the STF symbol values cover at least a portion of bandwidth of a first size, and

each of the STF symbol values is repeated one or more times for different subcarriers;

rotate phases of symbols of the STF sequence per bandwidth of the first size in an effort to reduce a peak-to-average power ratio (PAPR) during transmission of the STF sequence; and

transmit the STF sequence over a wireless channel by utilizing a bandwidth of a second size.

35. An access point, comprising:

at least one antenna;

a first circuit configured to construct a short training field (STF) sequence with a repetition period by using STF symbol values associated with the IEEE 802.11n standard, wherein

the STF symbol values cover at least a portion of bandwidth of a first size, and

each of the STF symbol values is repeated one or more times for different subcarriers;

a second circuit configured to rotate phases of symbols of the STF sequence per bandwidth of the first size in an effort to reduce a peak-to-average power ratio (PAPR) during transmitting the STF sequence; and

a transmitter configured to transmit, via the at least one antenna, the STF sequence over a wireless channel by utilizing a bandwidth of a second size.