Method and apparatus for improving throughput of 5 MHZ WLAN transmissions
Certain aspects of the present disclosure relate to techniques for improving a transmission throughput of communications based on IEEE 802.11af physical (PHY) layer in television white space (TVWS) spectrum. In one aspect, a transmission preamble with a Legacy Signal (L-SIG) field is constructed, wherein the L-SIG field comprises a code indicating duration of a cyclic prefix (CP) of a packet following the preamble. The transmissions can be performed using 5 MHz bandwidth of the TVWS spectrum.
1. A method for wireless communications, comprising:
constructing a preamble with a Legacy Signal (L-SIG) field, wherein the L-SIG field comprises a code indicating a duration of cyclic prefix (CP) of a packet following the preamble, wherein the preamble comprises an indication of a size of the packet; and
transmitting the preamble over a channel.
2. The method of claim 1 , wherein:
the duration of CP is approximately 1.6 μsec for a duration of the packet of approximately 16 μsec; and
a bandwidth of the channel is approximately 5 MHz.
3. The method of claim 1 , wherein the code is transmitted on a Q-rail of the L-SIG field.
4. The method of claim 3 , wherein the code is transmitted on all data tones of the Q-rail at one-half amplitude of tones of an I-rail of the L-SIG field.
5. The method of claim 1 , wherein the code comprises a random code with a peak-to-average power ratio (PAPR) below a threshold.
6. The method of claim 1 , wherein the L-SIG field further comprises an indication about a byte size equal at most to a number of bytes in a Physical Protocol Data Unit (PPDU) following the preamble.
7. The method of claim 6 , wherein a difference in bytes between the number of bytes in the PPDU and the byte size in the indication about the byte size is stored in a Service field of the preamble.
8. The method of claim 1 , wherein:
the code further indicates a change in tone allocation for transmitting the packet,
the preamble is transmitted in accordance with IEEE 802.11n wireless communications standard, and
a bandwidth of the channel is approximately 20 MHz.
9. The method of claim 8 , wherein the change in tone allocation comprises utilizing 52 data tones for transmitting the packet after previously utilizing 48 data tones.
10. The method of claim 1 , wherein the preamble is transmitted in accordance with IEEE 802.11 family of wireless communications standards.
11. An apparatus for wireless communications, comprising:
means for constructing a preamble with a Legacy Signal (L-SIG) field, wherein the L-SIG field comprises a code indicating a duration of cyclic prefix (CP) of a packet following the preamble, wherein the preamble comprises an indication of a size of the packet; and
means for transmitting the preamble over a channel.
12. The apparatus of claim 11 , wherein:
the duration of CP is approximately 1.6 μsec for a duration of the packet of approximately 16 μsec, and
a bandwidth of the channel is approximately 5 MHz.
13. The apparatus of claim 11 , wherein the code is transmitted on a Q-rail of the L-SIG field.
14. The apparatus of claim 11 , wherein the code comprises a random code with a peak-to-average power ratio (PAPR) below a threshold.
15. The apparatus of claim 11 , wherein the L-SIG field further comprises an indication about a byte size equal at most to a number of bytes in a Physical Protocol Data Unit (PPDU) following the preamble.
16. The apparatus of claim 15 , wherein a difference in bytes between the number of bytes in the PPDU and the byte size in the indication about the byte size is stored in a Service field of the preamble.
17. The apparatus of claim 11 , wherein:
the code further indicates a change in tone allocation for transmitting the packet,
the preamble is transmitted in accordance with IEEE 802.11n wireless communications standard, and
a bandwidth of the channel is approximately 20 MHz.
18. The apparatus of claim 17 , wherein the change in tone allocation comprises utilizing 52 data tones for transmitting the packet after previously utilizing 48 data tones.
19. The apparatus of claim 11 , wherein the preamble is transmitted in accordance with IEEE 802.11 family of wireless communications standards.
20. The apparatus of claim 11 , wherein the code is transmitted on all data tones of the Q-rail at one-half amplitude of tones of an I-rail of the L-SIG field.
21. An apparatus for wireless communications, comprising:
a circuit configured to construct a preamble with a Legacy Signal (L-SIG) field, wherein the L-SIG field comprises a code indicating a duration of cyclic prefix (CP) of a packet following the preamble, wherein the preamble comprises an indication of a size of the packet; and
a transmitter configured to transmit the preamble over a channel.
22. A non-transitory computer-readable medium comprising instructions executable to:
construct a preamble with a Legacy Signal (L-SIG) field, wherein the L-SIG field comprises a code indicating a duration of cyclic prefix (CP) of a packet following the preamble, wherein the preamble comprises an indication of a size of the packet; and
transmit the preamble over a channel.
23. An access point, comprising:
at least one antenna;
a circuit configured to construct a preamble with a Legacy Signal (L-SIG) field, wherein the L-SIG field comprises a code indicating a duration of cyclic prefix (CP) of a packet following the preamble, wherein the preamble comprises an indication of a size of the packet; and
a transmitter configured to transmit the preamble over a channel via the at least one antenna.
24. A method for wireless communications, comprising:
receiving a preamble with a Legacy Signal (L-SIG) field, wherein the L-SIG field comprises a code indicating a duration of cyclic prefix (CP) of a packet following the preamble, wherein the preamble comprises an indication of a size of the packet; and
decoding the L-SIG field.
25. The method of claim 24 , wherein decoding the L-SIG field further comprises:
determining the duration of CP.
26. The method of claim 24 , wherein a Q-rail of the L-SIG field comprises the code.
27. The method of claim 24 , wherein the code comprises a random code with a peak-to-average power ratio (PAPR) below a threshold.
28. The method of claim 24 , wherein decoding the L-SIG field further comprises:
determining an indication about duration of a frame following the preamble, and the method further comprising
deferring based on the duration.
29. The method of claim 28 , wherein the indication about duration of the frame comprises a byte size equal at most to a number of bytes in a Physical Protocol Data Unit (PPDU) of the frame.
30. The method of claim 29 , further comprising:
determining, based on a Service field of the preamble, a difference in bytes between the number of bytes in PPDU and the byte size in the indication about duration of the frame.
31. The method of claim 24 , further comprising:
determining, based on the code, a change in tone allocation utilized for transmission of the packet, wherein
the preamble was transmitted over a channel in accordance with IEEE 802.11n wireless communications standard, and
a bandwidth of the channel is approximately 20 MHz.
32. The method of claim 31 , wherein the change in tone allocation comprises utilizing 52 data tones for the transmission of the packet after previously utilizing 48 data tones.
33. The method of claim 32 , further comprising:
estimating the channel at extra tones −28, −27, 27, 28 of the packet based on a Legacy Long Training Field (L-LTF) of the preamble; and
storing values of the estimated channel at the extra tones.
34. The method of claim 33 , further comprising:
upon detecting the code, utilizing the stored values of the estimated channel.
35. A method for wireless communications, comprising:
receiving a preamble with a Legacy Signal (L-SIG) field, wherein the L-SIG field comprises a code indicating a duration of cyclic prefix (CP) of a packet following the preamble;
decoding the L-SIG field; and
detecting that the duration of CP is of a first size, if
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where k is a subcarrier index, c (k) is a value of the code for that subcarrier index, s (k) is a tone of the L-SIG field for that subcarrier index, N is a number of subcarriers associated with the L-SIG field, and r is a threshold.
36. The method of claim 35 , wherein:
the first size is equal to approximately 1.6 μsec for a duration of the packet of approximately 16 μsec,
the preamble was transmitted over a channel in accordance with IEEE 802.11 family of wireless communications standards, and
a bandwidth of the channel is approximately 5 MHz.
37. A method for wireless communications, comprising:
receiving a preamble with a Legacy Signal (L-SIG) field;
decoding the L-SIG field, wherein decoding the L-SIG field comprises determining a number of bytes in a frame following the preamble indicated in the L-SIG field; and
determining a location of a Frame Check Sequence (FCS) field within the frame based on the number of bytes.
38. An apparatus for wireless communications, comprising:
means for receiving a preamble with a Legacy Signal (L-SIG) field, wherein the L-SIG field comprises a code indicating a duration of cyclic prefix (CP) of a packet following the preamble, wherein the preamble comprises an indication of a size of the packet; and
means for decoding the L-SIG field.
39. The apparatus of claim 38 , wherein the means for decoding the L-SIG field further comprises:
means for determining the duration of CP.
40. The apparatus of claim 38 , wherein a Q-rail of the L-SIG field comprises the code.
41. The apparatus of claim 38 , wherein the code comprises a random code with a peak-to-average power ratio (PAPR) below a threshold.
42. The apparatus of claim 38 , wherein the means for decoding the L-SIG field comprises:
means for determining an indication about duration of a frame following the preamble, and the apparatus further comprising
means for deferring based on the duration.
43. The apparatus of claim 42 , wherein the indication about the duration of the frame comprises a byte size equal at most to a number of bytes in a Physical Protocol Data Unit (PPDU) of the frame.
44. The apparatus of claim 43 , further comprising:
means for determining, based on a Service field of the preamble, a difference in bytes between the number of bytes in the PPDU and the byte size in the indication about the duration of the frame.
45. The apparatus of claim 38 , further comprising:
means for determining, based on the code, a change in tone allocation utilized for transmission of the packet, wherein
the preamble was transmitted over a channel in accordance with IEEE 802.11n wireless communications standard, and
a bandwidth of the channel is approximately 20 MHz.
46. The apparatus of claim 45 , wherein the change in tone allocation comprises utilizing 52 data tones for the transmission of the packet after previously utilizing 48 data tones.
47. The apparatus of claim 46 , further comprising:
means for estimating the channel at extra tones −28, −27, 27, 28 of the packet based on a Legacy Long Training Field (L-LTF) of the preamble; and
means for storing values of the estimated channel at the extra tones.
48. The apparatus of claim 47 , further comprising:
means for utilizing the stored values of the estimated channel, upon detecting the code.
49. An apparatus for wireless communications, comprising:
means for receiving a preamble with a Legacy Signal (L-SIG) field, wherein the L-SIG field comprises a code indicating a duration of cyclic prefix (CP) of a packet following the preamble;
means for decoding the L-SIG field; and
means for detecting that the duration of CP is of a first size, if
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where k is a subcarrier index, c(k) is a value of the code for that subcarrier index, s(k) is a tone of the L-SIG field for that subcarrier index, N is a number of subcarriers associated with the L-SIG field, and r is a threshold.
50. The apparatus of claim 49 , wherein:
the first size is equal to approximately 1.6 μsec for a duration of the packet of approximately 16 μsec,
the preamble was transmitted over a channel in accordance with IEEE 802.11 family of wireless communications standards, and
a bandwidth of the channel is approximately 5 MHz.
51. An apparatus for wireless communications, comprising:
means for receiving a preamble with a Legacy Signal (L-SIG) field;
means for decoding the L-SIG field, wherein the means for decoding the L-SIG field comprises means for determining a number of bytes in a frame following the preamble indicated in the L-SIG field; and
means for determining location of a Frame Check Sequence (FCS) field within the frame based on the number of bytes.
52. An apparatus for wireless communications, comprising:
a receiver configured to receive a preamble with a Legacy Signal (L-SIG) field, wherein the L-SIG field comprises a code indicating a duration of cyclic prefix (CP) of a packet following the preamble, wherein the preamble comprises an indication of a size of the packet; and
a circuit configured to decode the L-SIG field.
53. A non-transitory computer-readable medium comprising instructions executable to:
receive a preamble with a Legacy Signal (L-SIG) field, wherein the L-SIG field comprises a code indicating a duration of cyclic prefix (CP) of a packet following the preamble, wherein the preamble comprises an indication of a size of the packet; and
decode the L-SIG field.
54. An access terminal, comprising:
at least one antenna;
a receiver configured to receive, via the at least one antenna, a preamble with a Legacy Signal (L-SIG) field, wherein the L-SIG field comprises a code indicating a duration of cyclic prefix (CP) of a packet following the preamble, wherein the preamble comprises an indication of a size of the packet; and
a circuit configured to decode the L-SIG field.