Backward-Compatible Long Training Sequences for Wireless Communication Networks

1. A wireless communications device, comprising: a signal generator that generates an extended long training sequence; and an Inverse Fourier Transformer operatively coupled to the signal generator, wherein the Inverse Fourier Transformer processes the extended long training sequence from the signal generator and provides an optimal extended long training sequence with a minimal peak-to-average ratio, and wherein at least the optimal extended long training sequence is carried by a greater number of subcarriers than a standard wireless networking configuration for an Orthogonal Frequency Division Multiplexing scheme.

2. The wireless communications device according to claim 1, wherein at least the optimal extended long training sequence is carried by at least 56 active sub-carriers.

3. The wireless communications device according to claim 2, wherein the at least 56 active sub-carriers correspond to at least indexed sub-carriers −28 to +28.

4. The wireless communications device according to claim 2, wherein the optimal extended long training sequence has a minimum peak-to-average power ratio of 3.6 dB.

5. The wireless communications device according to claim 1, wherein at least the optimal extended long training sequence is carried by at least 63 active sub-carriers.

6. The wireless communications device according to claim 5, wherein the at least 63 active sub-carriers correspond to at least indexed sub-carriers −32 to +31.

7. The wireless communications device according to claim 5, wherein the optimal extended long training sequence has a minimum peak-to-average power ratio of 3.6 dB.

8. The wireless communications device according to claim 1, wherein a binary phase shift key encoding is used for each sub-carrier above the +26 indexed sub-carrier and below the −26 indexed sub-carrier.

9. The wireless communications device according to claim 1, wherein the Inverse Fourier Transformer comprises at least one of the following: an Inverse Fast Fourier Transformer and an Inverse Discrete Fourier Transformer.

10. The wireless communications device according to claim 1, wherein the wireless communications device comprises one or more of the following: a personal digital assistant, a laptop computer, a personal computer and a cellular phone.

11. The wireless communications device according to claim 1, wherein the wireless communications device comprises a wireless mobile communications device.

12. The wireless communications device according to claim 1, wherein the wireless communications device comprises one or more of the following: an access point and a base station.

13. The wireless communications device according to claim 1, wherein the wireless communications device is backwards compatible with legacy wireless local area network devices.

14. The wireless communications device according to claim 1, wherein the optimal extended long training sequence is longer than a long training sequence used by a legacy wireless local area network device in accordance with a legacy wireless networking protocol standard.

15. The wireless communications device according to claim 14, wherein the legacy wireless local area network device uses the optimal extended long training sequence to estimate a carrier frequency offset even though the optimal extended long training sequence is longer than the long training sequence that is specified by the legacy wireless networking protocol standard.

16. The wireless communications device according to claim 15, wherein the long training sequence that is specified by the legacy wireless networking protocol standard is maintained in the extended long training sequence or the optimal extended long training sequence.

17. The wireless communications device according to claim 1, wherein the wireless communications device decreases power back-off.

18. The wireless communications device according to claim 1, wherein the wireless communications device registers with one or more of the following: an access point and a base station.

19. The wireless communications device according to claim 1, wherein the extended long training sequence or the optimal extended long training sequence is encoded using binary phase shift key encoding on each of the subcarriers.

20. The wireless communications device according to claim 1, comprising: a symbol mapper operatively coupled to the signal generator, wherein the symbol mapper receives coded bits and generates symbols for each of 64 subcarriers of an Orthogonal Frequency Division Multiplexing sequence.

21. A wireless communications device, comprising: a signal generator that generates an extended long training sequence; and an Inverse Fourier Transformer operatively coupled to the signal generator, wherein the Inverse Fourier Transformer processes the extended long training sequence from the signal generator and provides an optimal extended long training sequence with a minimal peak-to-average ratio, and wherein at least the optimal extended long training sequence is carried by a greater number of subcarriers than a standard wireless networking configuration for an Orthogonal Frequency Division Multiplexing scheme, and wherein the optimal extended long training sequence includes (i) standard encodings for a training sequence for the subcarriers of the standard wireless networking configuration and (ii) one or more encodings for one or more additional subcarriers of the optimal extended long training sequence that are different from the subcarriers of the standard wireless networking configuration.

22. The wireless communications device according to claim 21, wherein at least the optimal extended long training sequence is carried by at least 56 active sub-carriers.

23. The wireless communications device according to claim 22, wherein the at least 56 active sub-carriers correspond to at least indexed sub-carriers −28 to +28.

24. The wireless communications device according to claim 22, wherein the optimal extended long training sequence has a minimum peak-to-average power ratio of 3.6 dB.

25. The wireless communications device according to claim 21, wherein at least the optimal extended long training sequence is carried by at least 63 active sub-carriers.

26. The wireless communications device according to claim 25, wherein the at least 63 active sub-carriers correspond to at least indexed sub-carriers −32 to +31.

27. The wireless communications device according to claim 25, wherein the optimal extended long training sequence has a minimum peak-to-average power ratio of 3.6 dB.

28. The wireless communications device according to claim 21, wherein a binary phase shift key encoding is used for each sub-carrier above the +26 indexed sub-carrier and below the −26 indexed sub-carrier.

29. The wireless communications device according to claim 21, wherein the Inverse Fourier Transformer comprises at least one of the following: an Inverse Fast Fourier Transformer and an Inverse Discrete Fourier Transformer.

30. The wireless communications device according to claim 21, wherein the wireless communications device comprises one or more of the following: a personal digital assistant, a laptop computer, a personal computer and a cellular phone.

31. The wireless communications device according to claim 21, wherein the wireless communications device comprises a wireless mobile communications device.

32. The wireless communications device according to claim 21, wherein the wireless communications device comprises one or more of the following: an access point and a base station.

33. The wireless communications device according to claim 21, wherein the wireless communications device is backwards compatible with legacy wireless local area network devices.

34. The wireless communications device according to claim 21, wherein the optimal extended long training sequence is longer than a long training sequence used by a legacy wireless local area network device in accordance with a legacy wireless networking protocol standard.

35. The wireless communications device according to claim 34, wherein the legacy wireless local area network device uses the optimal extended long training sequence to estimate a carrier frequency offset even though the optimal extended long training sequence is longer than the long training sequence that is specified by the legacy wireless networking protocol standard.

36. The wireless communications device according to claim 35, wherein the long training sequence that is specified by the legacy wireless networking protocol standard is maintained in the extended long training sequence or the optimal extended long training sequence.

37. The wireless communications device according to claim 21, wherein the wireless communications device decreases power back-off.

38. The wireless communications device according to claim 21, wherein the wireless communications device registers with one or more of the following: an access point and a base station.

39. The wireless communications device according to claim 21, wherein the extended long training sequence or the optimal extended long training sequence is encoded using binary phase shift key encoding on each of the subcarriers.

40. The wireless communications device according to claim 21, comprising: a symbol mapper operatively coupled to the signal generator, wherein the symbol mapper receives coded bits and generates symbols for each of 64 subcarriers of an Orthogonal Frequency Division Multiplexing sequence.

41. The wireless communications device according to claim 21, wherein the optimal extended long training sequence is carried by exactly 63 active sub-carriers.

42. The wireless communications device according to claim 41, wherein the optimal extended long training sequence is represented by encodings for indexed sub-carriers −32 to +31, excluding indexed sub-carrier 0 which is set to zero, as follows:, Sub-carrier −32 −31 −30 −29 −28 −27 Encoding −1 −1 +1 +1 +1 +1 Sub-carrier −26 −25 −24 −23 −22 −21 −20 −19 −18 −17 −16 −15 −14 Encoding +1 +1 −1 −1 +1 +1 −1 +1 −1 +1 +1 +1 +1 Sub-carrier −13 −12 −11 −10 −9 −8 −7 −6 −5 −4 −3 −2 −1 Encoding +1 +1 −1 −1 +1 +1 −1 +1 −1 +1 +1 +1 +1 Sub-carrier 1 2 3 4 5 6 7 8 9 10 11 12 13 Encoding +1 −1 −1 +1 +1 −1 +1 −1 +1 −1 −1 −1 −1 Sub-carrier 14 15 16 17 18 19 20 21 22 23 24 25 26 Encoding −1 +1 +1 −1 −1 +1 −1 +1 −1 +1 +1 +1 +1 Sub-carrier 27 28 29 30 31 Encoding −1 −1 −1 +1 −1.,

43. The wireless communications device according to claim 21, wherein: the standard wireless networking configuration has 52 subcarriers comprising subcarriers −26 to −1 and +1 to +26; and the one or more additional subcarriers of the optimal extended long training sequence comprise one or more subcarriers below subcarrier −26 and one or more subcarriers above subcarrier +26.

44. The wireless communications device according to claim 43, wherein encodings for the sub-carriers −26 to −1 and +1 to +26 are as follows:, Sub-carrier −26 −25 −24 −23 −22 −21 −20 −19 −18 −17 −16 −15 −14 Encoding +1 +1 −1 −1 +1 +1 −1 +1 −1 +1 +1 +1 +1 Sub-carrier −13 −12 −11 −10 −9 −8 −7 −6 −5 −4 −3 −2 −1 Encoding +1 +1 −1 −1 +1 +1 −1 +1 −1 +1 +1 +1 +1 Sub-carrier 1 2 3 4 5 6 7 8 9 10 11 12 13 Encoding +1 −1 −1 +1 +1 −1 +1 −1 +1 −1 −1 −1 −1 Sub-carrier 14 15 16 17 18 19 20 21 22 23 24 25 26 Encoding −1 +1 +1 −1 −1 +1 −1 +1 −1 +1 +1 +1 +1.,

45. The wireless communications device according to claim 43, wherein the one or more additional subcarriers of the optimal extended long training sequence consist of subcarriers −28, −27, +27, and +28.

46. The wireless communications device according to claim 21, wherein the optimal extended long training sequence is carried by exactly 56 active sub-carriers.

47. The wireless communications device according to claim 46, wherein the optimal extended long training sequence is represented by encodings for indexed sub-carriers −28 to +28, excluding indexed sub-carrier 0 which is set to zero, as follows:, Sub-carrier −28 −27 Encoding +1 +1 Sub-carrier −26 −25 −24 −23 −22 −21 −20 −19 −18 −17 −16 −15 −14 Encoding +1 +1 −1 −1 +1 +1 −1 +1 −1 +1 +1 +1 +1 Sub-carrier −13 −12 −11 −10 −9 −8 −7 −6 −5 −4 −3 −2 −1 Encoding +1 +1 −1 −1 +1 +1 −1 +1 −1 +1 +1 +1 +1 Sub-carrier 1 2 3 4 5 6 7 8 9 10 11 12 13 Encoding +1 −1 −1 +1 +1 −1 +1 −1 +1 −1 −1 −1 −1 Sub-carrier 14 15 16 17 18 19 20 21 22 23 24 25 26 Encoding −1 +1 +1 −1 −1 +1 −1 +1 −1 +1 +1 +1 +1 Sub-carrier 27 28 Encoding −1 −1.,

48. The wireless communications device according to claim 21, wherein at least one output of the Inverse Fourier Transformer is operatively coupled to at least one digital-to-analog converter.

49. The wireless communications device according to claim 21, wherein at least one output of the Inverse Fourier Transformer is operatively coupled to multiple digital-to-analog converters.

50. The wireless communications device according to claim 21, wherein an input of the signal generator is operatively coupled to a frequency-domain windower.

51. The wireless communications device according to claim 21, wherein an output of the Inverse Fourier Transformer is operatively coupled to a time-domain windower.

52. The wireless communications device according to claim 51, wherein an output of the time-domain windower is operatively coupled to at least one digital-to-analog converter.

53. The wireless communication device according to claim 21, wherein an output of the Inverse Fourier Transformer is operatively coupled to a digital transmit filter.

54. The wireless communications device according to claim 21, wherein an output of the Inverse Fourier Transformer is operatively coupled to a parallel-to-serial convertor.

55. The wireless communications device according to claim 21, wherein the wireless communications device is configured to convert parallel frequency-domain signals into serial time-domain signals.