FORMAT OF VHT-SIG-B AND SERVICE FIELDS IN IEEE 802.11AC

• US 20110299468A1
• Filed: 05/31/2011
• Published: 12/08/2011
• Est. Priority Date: 06/02/2010
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Van Nee, Didier Johannes Richard, Van Zelst, Albert, Merlin, Simone, Sampath, Hemanth
• Granted Patent: US 8,867,574 B2
• Time in Patent Office: Days
• US Class Current: 370/328
• CPC Class Codes: H04L 27/2613 Structure of the reference signals

Abstract

Methods and apparatus for transmitting and receiving frames with various Very High Throughput Signal B (VHT-SIG-B) and Service field formats are provided. Some of these formats may be in accordance with the IEEE 802.11ac amendment to the wireless local area network (WLAN) standard.

Claims

1. A method for wireless communications, comprising:

generating a frame having a preamble portion and a data portion, wherein the preamble portion comprises a field indicating a length of useful data in the data portion and wherein both the field and the data portion use the same number of subcarriers; and

transmitting the generated frame.

2. The method of claim 1, wherein the field comprises a Very High Throughput Signal B (VHT-SIG-B) field.

3. The method of claim 1, wherein the transmitting comprises transmitting the frame over a channel, wherein a bandwidth of the channel is about 20 MHz, and wherein the field comprises 26 pre-coded bits.

4. The method of claim 3, wherein the transmitting comprises transmitting the frame over a channel, wherein a bandwidth of the channel is about 80 MHz, and wherein the field comprises four blocks with the same 29 pre-coded bits repeated in each block.

5. The method of claim 1, wherein the transmitting comprises transmitting the frame over a channel, wherein a bandwidth of the channel is about 20 MHz, and wherein the number of subcarriers is 56.

6. The method of claim 5, wherein the number of subcarriers comprises 4 pilot subcarriers and 52 data subcarriers for both the field and the data portion.

7. The method of claim 1, wherein the transmitting comprises transmitting the frame over a channel, wherein a bandwidth of the channel is about 40 MHz, and wherein the number of subcarriers is 114.

8. The method of claim 1, wherein the generating comprises:

determining a bandwidth of a channel for the transmitting;

generating a block of bits based on the determined bandwidth; and

repeating the block of bits a number of times according to the determined bandwidth to generate the field in the frame.

9. The method of claim 8, wherein the determined bandwidth is about 160 MHz, wherein the block of bits comprises 29 pre-coded bits, and wherein the repeating comprises repeating the block of bits eight times such that the field comprises at least 232 pre-coded bits.

10. The method of claim 1, wherein the data portion comprises another field used for scrambler initialization, wherein the other field comprises a cyclic redundancy check (CRC) associated with the field indicating the length of the useful data.

11. The method of claim 1, wherein the field comprises a long guard interval (GI) of about 800 ns.

12. An apparatus for wireless communications, comprising:

a processing system configured to generate a frame having a preamble portion and a data portion, wherein the preamble portion comprises a field indicating a length of useful data in the data portion and wherein both the field and the data portion use the same number of subcarriers; and

a transmitter configured to transmit the generated frame.

13. The apparatus of claim 12, wherein the field comprises a Very High Throughput Signal B (VHT-SIG-B) field.

14. The apparatus of claim 12, wherein the transmitter is configured to transmit the frame over a channel, wherein a bandwidth of the channel is about 20 MHz, and wherein the field comprises 26 pre-coded bits.

15. The apparatus of claim 14, wherein the transmitter is configured to transmit the frame over a channel, wherein a bandwidth of the channel is about 80 MHz, and wherein the field comprises four blocks with the same 29 pre-coded bits repeated in each block.

16. The apparatus of claim 12, wherein the transmitter is configured to transmit the frame over a channel, wherein a bandwidth of the channel is about 20 MHz, and wherein the number of subcarriers is 56.

17. The apparatus of claim 16, wherein the number of subcarriers comprises 4 pilot subcarriers and 52 data subcarriers for both the field and the data portion.

18. The apparatus of claim 12, wherein the transmitter is configured to transmit the frame over a channel, wherein a bandwidth of the channel is about 40 MHz, and wherein the number of subcarriers is 114.

19. The apparatus of claim 12, wherein the processing system is configured to generate the frame by:

determining a bandwidth of a channel for the transmitter to transmit the frame;

generating a block of bits based on the determined bandwidth; and

repeating the block of bits a number of times according to the determined bandwidth to generate the field in the frame.

20. The apparatus of claim 19, wherein the determined bandwidth is about 160 MHz, wherein the block of bits comprises 29 pre-coded bits, and wherein the repeating comprises repeating the block of bits eight times such that the field comprises at least 232 pre-coded bits.

21. The apparatus of claim 12, wherein the data portion comprises another field used for scrambler initialization, wherein the other field comprises a cyclic redundancy check (CRC) associated with the field indicating the length of the useful data.

22. The apparatus of claim 12, wherein the field comprises a long guard interval (GI) of about 800 ns.

23. An apparatus for wireless communications, comprising:

means for generating a frame having a preamble portion and a data portion, wherein the preamble portion comprises a field indicating a length of useful data in the data portion and wherein both the field and the data portion use the same number of subcarriers; and

means for transmitting the generated frame.

24. The apparatus of claim 23, wherein the field comprises a Very High Throughput Signal B (VHT-SIG-B) field.

25. The apparatus of claim 23, wherein the means for transmitting is configured to transmit the frame over a channel, wherein a bandwidth of the channel is about 20 MHz, and wherein the field comprises 26 pre-coded bits.

26. The apparatus of claim 25, wherein the means for transmitting is configured to transmit the frame over a channel, wherein a bandwidth of the channel is about 80 MHz, and wherein the field comprises four blocks with the same 29 pre-coded bits repeated in each block.

27. The apparatus of claim 23, wherein the means for transmitting is configured to transmit the frame over a channel, wherein a bandwidth of the channel is about 20 MHz, and wherein the number of subcarriers is 56.

28. The apparatus of claim 27, wherein the number of subcarriers comprises 4 pilot subcarriers and 52 data subcarriers for both the field and the data portion.

29. The apparatus of claim 23, wherein the means for transmitting is configured to transmit the frame over a channel, wherein a bandwidth of the channel is about 40 MHz, and wherein the number of subcarriers is 114.

30. The apparatus of claim 23, wherein the means for generating is configured to:

determine a bandwidth of a channel for the means for transmitting to transmit the frame;

generate a block of bits based on the determined bandwidth; and

repeat the block of bits a number of times according to the determined bandwidth to generate the field in the frame.

31. The apparatus of claim 30, wherein the determined bandwidth is about 160 MHz, wherein the block of bits comprises 29 pre-coded bits, and wherein the repeating comprises repeating the block of bits eight times such that the field comprises at least 232 pre-coded bits.

32. The apparatus of claim 23, wherein the data portion comprises another field used for scrambler initialization, wherein the other field comprises a cyclic redundancy check (CRC) associated with the field indicating the length of the useful data.

33. The apparatus of claim 23, wherein the field comprises a long guard interval (GI) of about 800 ns.

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

generate a frame having a preamble portion and a data portion, wherein the preamble portion comprises a field indicating a length of useful data in the data portion and wherein both the field and the data portion use the same number of subcarriers; and

transmit the generated frame.

35. The computer-program product of claim 34, wherein the field comprises a Very High Throughput Signal B (VHT-SIG-B) field.

36. The computer-program product of claim 34, wherein the instructions are executable to transmit the generated frame by transmitting the frame over a channel, wherein a bandwidth of the channel is about 20 MHz, and wherein the field comprises 26 pre-coded bits.

37. The computer-program product of claim 36, wherein the instructions are executable to transmit the generated frame by transmitting the frame over a channel, wherein a bandwidth of the channel is about 80 MHz, and wherein the field comprises four blocks with the same 29 pre-coded bits repeated in each block.

38. The computer-program product of claim 34, wherein the instructions are executable to transmit the generated frame by transmitting the frame over a channel, wherein a bandwidth of the channel is about 20 MHz, and wherein the number of subcarriers is 56.

39. The computer-program product of claim 38, wherein the number of subcarriers comprises 4 pilot subcarriers and 52 data subcarriers for both the field and the data portion.

40. The computer-program product of claim 34, wherein the instructions are executable to transmit the generated frame by transmitting the frame over a channel, wherein a bandwidth of the channel is about 40 MHz, and wherein the number of subcarriers is 114.

41. The computer-program product of claim 34, wherein the instructions are executable to generate the frame by:

determining a bandwidth of a channel for transmitting the frame;

generating a block of bits based on the determined bandwidth; and

repeating the block of bits a number of times according to the determined bandwidth to generate the field in the frame.

42. The computer-program product of claim 41, wherein the determined bandwidth is about 160 MHz, wherein the block of bits comprises 29 pre-coded bits, and wherein the repeating comprises repeating the block of bits eight times such that the field comprises at least 232 pre-coded bits.

43. The computer-program product of claim 34, wherein the data portion comprises another field used for scrambler initialization, wherein the other field comprises a cyclic redundancy check (CRC) associated with the field indicating the length of the useful data.

44. The computer-program product of claim 34, wherein the field comprises a long guard interval (GI) of about 800 ns.

45. A method for wireless communications, comprising:

receiving a frame having a preamble portion and a data portion, wherein the preamble portion comprises a field indicating a length of useful data in the data portion and wherein both the field and the data portion use the same number of subcarriers; and

decoding the data portion based on the field.

46. The method of claim 45, wherein the field comprises a Very High Throughput Signal B (VHT-SIG-B) field.

47. The method of claim 45, wherein the receiving comprises receiving the frame over a channel, wherein a bandwidth of the channel is about 20 MHz, and wherein the field comprises 26 pre-coded bits.

48. The method of claim 47, wherein the receiving comprises receiving the frame over a channel, wherein a bandwidth of the channel is about 40 MHz, and wherein the field comprises two blocks with the same 27 pre-coded bits repeated in each block.

49. The method of claim 45, wherein the receiving comprises receiving the frame over a channel, wherein a bandwidth of the channel is about 20 MHz, and wherein the number of subcarriers is 56.

50. The method of claim 49, wherein the number of subcarriers comprises 4 pilot subcarriers and 52 data subcarriers for both the field and the data portion.

51. The method of claim 45, wherein the receiving comprises receiving the frame over a channel, wherein a bandwidth of the channel is about 80 MHz, and wherein the number of subcarriers is 242.

52. The method of claim 45, wherein the data portion comprises another field used for scrambler initialization, wherein the other field comprises a cyclic redundancy check (CRC) associated with the field indicating the length of the useful data.

53. The method of claim 45, further comprising stopping the decoding after reaching an end of the useful data based on the length of the useful data.

54. The method of claim 45, wherein the field comprises a long guard interval (GI) of about 800 ns.

55. An apparatus for wireless communications, comprising:

a receiver configured to receive a frame having a preamble portion and a data portion, wherein the preamble portion comprises a field indicating a length of useful data in the data portion and wherein both the field and the data portion use the same number of subcarriers; and

a processing system configured to decode the data portion based on the field.

56. The apparatus of claim 55, wherein the field comprises a Very High Throughput Signal B (VHT-SIG-B) field.

57. The apparatus of claim 55, wherein the receiver is configured to receive the frame over a channel, wherein a bandwidth of the channel is about 20 MHz, and wherein the field comprises 26 pre-coded bits.

58. The apparatus of claim 57, wherein the receiver is configured to receive the frame over a channel, wherein a bandwidth of the channel is about 40 MHz, and wherein the field comprises two blocks with the same 27 pre-coded bits repeated in each block.

59. The apparatus of claim 55, wherein the receiver is configured to receive the frame over a channel, wherein a bandwidth of the channel is about 20 MHz, and wherein the number of subcarriers is 56.

60. The apparatus of claim 59, wherein the number of subcarriers comprises 4 pilot subcarriers and 52 data subcarriers for both the field and the data portion.

61. The apparatus of claim 55, wherein the receiver is configured to receive the frame over a channel, wherein a bandwidth of the channel is about 80 MHz, and wherein the number of subcarriers is 242.

62. The apparatus of claim 55, wherein the data portion comprises another field used for scrambler initialization, wherein the other field comprises a cyclic redundancy check (CRC) associated with the field indicating the length of the useful data.

63. The apparatus of claim 55, wherein the processing system is configured to stop the decoding after reaching an end of the useful data based on the length of the useful data.

64. The apparatus of claim 55, wherein the field comprises a long guard interval (GI) of about 800 ns.

65. An apparatus for wireless communications, comprising:

means for receiving a frame having a preamble portion and a data portion, wherein the preamble portion comprises a field indicating a length of useful data in the data portion and wherein both the field and the data portion use the same number of subcarriers; and

means for decoding the data portion based on the field.

66. The apparatus of claim 65, wherein the field comprises a Very High Throughput Signal B (VHT-SIG-B) field.

67. The apparatus of claim 65, wherein the means for receiving is configured to receive the frame over a channel, wherein a bandwidth of the channel is about 20 MHz, and wherein the field comprises 26 pre-coded bits.

68. The apparatus of claim 67, wherein the means for receiving is configured to receive the frame over a channel, wherein a bandwidth of the channel is about 40 MHz, and wherein the field comprises two blocks with the same 27 pre-coded bits repeated in each block.

69. The apparatus of claim 65, wherein the means for receiving is configured to receive the frame over a channel, wherein a bandwidth of the channel is about 20 MHz, and wherein the number of subcarriers is 56.

70. The apparatus of claim 69, wherein the number of subcarriers comprises 4 pilot subcarriers and 52 data subcarriers for both the field and the data portion.

71. The apparatus of claim 65, wherein the means for receiving is configured to receive the frame over a channel, wherein a bandwidth of the channel is about 80 MHz, and wherein the number of subcarriers is 242.

72. The apparatus of claim 65, wherein the data portion comprises another field used for scrambler initialization, wherein the other field comprises a cyclic redundancy check (CRC) associated with the field indicating the length of the useful data.

73. The apparatus of claim 65, wherein the means for decoding is configured to stop the decoding after reaching an end of the useful data based on the length of the useful data.

74. The apparatus of claim 65, wherein the field comprises a long guard interval (GI) of about 800 ns.

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

receive a frame having a preamble portion and a data portion, wherein the preamble portion comprises a field indicating a length of useful data in the data portion and wherein both the field and the data portion use the same number of subcarriers; and

decode the data portion based on the field.

76. The computer-program product of claim 75, wherein the field comprises a Very High Throughput Signal B (VHT-SIG-B) field.

77. The computer-program product of claim 75, wherein the receiving comprises receiving the frame over a channel, wherein a bandwidth of the channel is about 20 MHz, and wherein the field comprises 26 pre-coded bits.

78. The computer-program product of claim 77, wherein the receiving comprises receiving the frame over a channel, wherein a bandwidth of the channel is about 40 MHz, and wherein the field comprises two blocks with the same 27 pre-coded bits repeated in each block.

79. The computer-program product of claim 75, wherein the receiving comprises receiving the frame over a channel, wherein a bandwidth of the channel is about 20 MHz, and wherein the number of subcarriers is 56.

80. The computer-program product of claim 79, wherein the number of subcarriers comprises 4 pilot subcarriers and 52 data subcarriers for both the field and the data portion.

81. The computer-program product of claim 75, wherein the receiving comprises receiving the frame over a channel, wherein a bandwidth of the channel is about 80 MHz, and wherein the number of subcarriers is 242.

82. The computer-program product of claim 75, wherein the data portion comprises another field used for scrambler initialization, wherein the other field comprises a cyclic redundancy check (CRC) associated with the field indicating the length of the useful data.

83. The computer-program product of claim 75, further comprising stopping the decoding after reaching an end of the useful data based on the length of the useful data.

84. The computer-program product of claim 75, wherein the field comprises a long guard interval (GI) of about 800 ns.

85. A method for wireless communications, comprising:

generating a frame having a preamble portion and a data portion, wherein the preamble portion comprises a field indicating a length of useful data in the data portion; and

transmitting the generated frame via a channel, wherein the generating comprises;

determining a bandwidth of the channel for the transmitting;

generating a block of bits based on the determined bandwidth; and

repeating the block of bits a number of times according to the determined bandwidth to generate the field in the frame.

86. The method of claim 85, wherein the field comprises a Very High Throughput Signal B (VHT-SIG-B) field.

87. The method of claim 85, wherein the bandwidth of the channel is about 40 MHz, wherein the block of bits comprises 27 pre-coded bits, and wherein the repeating comprises repeating the block of bits two times such that the field comprises at least 54 pre-coded bits.

88. The method of claim 85, wherein the bandwidth of the channel is about 80 MHz, wherein the block of bits comprises 29 pre-coded bits, and wherein the repeating comprises repeating the block of bits four times such that the field comprises at least 126 pre-coded bits.

89. The method of claim 85, wherein the bandwidth of the channel is about 160 MHz and wherein the field uses about 484 subcarriers.

90. The method of claim 85, wherein the data portion comprises another field used for scrambler initialization, wherein the other field comprises a cyclic redundancy check (CRC) associated with the field indicating the length of the useful data.

91. The method of claim 85, wherein the field comprises a long guard interval (GI) of about 800 ns.

92. An apparatus for wireless communications, comprising:

a processing system configured to generate a frame having a preamble portion and a data portion, wherein the preamble portion comprises a field indicating a length of useful data in the data portion; and

a transmitter configured to transmit the generated frame via a channel, wherein the processing system is configured to generate the frame by;

determining a bandwidth of the channel for the transmitter to transmit the frame;

generating a block of bits based on the determined bandwidth; and

repeating the block of bits a number of times according to the determined bandwidth to generate the field in the frame.

93. The apparatus of claim 92, wherein the field comprises a Very High Throughput Signal B (VHT-SIG-B) field.

94. The apparatus of claim 92, wherein the bandwidth of the channel is about 40 MHz, wherein the block of bits comprises 27 pre-coded bits, and wherein the repeating comprises repeating the block of bits two times such that the field comprises at least 54 pre-coded bits.

95. The apparatus of claim 92, wherein the bandwidth of the channel is about 80 MHz, wherein the block of bits comprises 29 pre-coded bits, and wherein the repeating comprises repeating the block of bits four times such that the field comprises at least 126 pre-coded bits.

96. The apparatus of claim 92, wherein the bandwidth of the channel is about 160 MHz and wherein the field uses about 484 subcarriers.

97. The apparatus of claim 92, wherein the data portion comprises another field used for scrambler initialization, wherein the other field comprises a cyclic redundancy check (CRC) associated with the field indicating the length of the useful data.

98. The apparatus of claim 92, wherein the field comprises a long guard interval (GI) of about 800 ns.

99. An apparatus for wireless communications, comprising:

means for generating a frame having a preamble portion and a data portion, wherein the preamble portion comprises a field indicating a length of useful data in the data portion; and

means for transmitting the generated frame via a channel, wherein the means for generating is configured to;

determine a bandwidth of the channel for transmitting the frame;

generate a block of bits based on the determined bandwidth; and

repeat the block of bits a number of times according to the determined bandwidth to generate the field in the frame.

100. The apparatus of claim 99, wherein the field comprises a Very High Throughput Signal B (VHT-SIG-B) field.

101. The apparatus of claim 99, wherein the bandwidth of the channel is about 40 MHz, wherein the block of bits comprises 27 pre-coded bits, and wherein the means for generating is configured to repeat the block of bits by repeating the block of bits two times such that the field comprises at least 54 pre-coded bits.

102. The apparatus of claim 99, wherein the bandwidth of the channel is about 80 MHz, wherein the block of bits comprises 29 pre-coded bits, and wherein the means for generating is configured to repeat the block of bits by repeating the block of bits four times such that the field comprises at least 126 pre-coded bits.

103. The apparatus of claim 99, wherein the bandwidth of the channel is about 160 MHz and wherein the field uses about 484 subcarriers.

104. The apparatus of claim 99, wherein the data portion comprises another field used for scrambler initialization, wherein the other field comprises a cyclic redundancy check (CRC) associated with the field indicating the length of the useful data.

105. The apparatus of claim 99, wherein the field comprises a long guard interval (GI) of about 800 ns.

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

generate a frame having a preamble portion and a data portion, wherein the preamble portion comprises a field indicating a length of useful data in the data portion; and

transmit the generated frame via a channel, wherein the instructions are executable to generate the frame by;

determining a bandwidth of the channel for transmitting the frame;

generating a block of bits based on the determined bandwidth; and

repeating the block of bits a number of times according to the determined bandwidth to generate the field in the frame.

107. The computer-program product of claim 106, wherein the field comprises a Very High Throughput Signal B (VHT-SIG-B) field.

108. The computer-program product of claim 106, wherein the bandwidth of the channel is about 40 MHz, wherein the block of bits comprises 27 pre-coded bits, and wherein the repeating comprises repeating the block of bits two times such that the field comprises at least 54 pre-coded bits.

109. The computer-program product of claim 106, wherein the bandwidth of the channel is about 80 MHz, wherein the block of bits comprises 29 pre-coded bits, and wherein the repeating comprises repeating the block of bits four times such that the field comprises at least 126 pre-coded bits.

110. The computer-program product of claim 106, wherein the bandwidth of the channel is about 160 MHz and wherein the field uses about 484 subcarriers.

111. The computer-program product of claim 106, wherein the data portion comprises another field used for scrambler initialization, wherein the other field comprises a cyclic redundancy check (CRC) associated with the field indicating the length of the useful data.

112. The computer-program product of claim 106, wherein the field comprises a long guard interval (GI) of about 800 ns.

113. A method for wireless communications, comprising:

receiving a frame having a preamble portion and a data portion, wherein the preamble portion comprises a field indicating a length of useful data in the data portion and wherein the field comprises a plurality of replicated blocks, such that bits of one of the blocks are repeated in each of the blocks; and

decoding the data portion based on the field.

114. The method of claim 113, wherein the field comprises a Very High Throughput Signal B (VHT-SIG-B) field.

115. The method of claim 113, wherein the receiving comprises receiving the frame over a channel, wherein a bandwidth of the channel is about 80 MHz, and wherein the field comprises four blocks with the same 29 pre-coded bits repeated in each of the blocks.

116. The method of claim 113, wherein the receiving comprises receiving the frame over a channel, wherein a bandwidth of the channel is about 160 MHz, and wherein the field comprises eight blocks with the same 29 pre-coded bits repeated in each of the blocks.

117. The method of claim 113, wherein the receiving comprises receiving the frame over a channel, wherein a bandwidth of the channel is about 40 MHz, and wherein the field uses about 114 subcarriers.

118. The method of claim 113, wherein the data portion comprises another field used for scrambler initialization and wherein the other field comprises a cyclic redundancy check (CRC) associated with the field indicating the length of the useful data.

119. The method of claim 113, further comprising stopping the decoding after reaching an end of the useful data based on the length of the useful data.

120. The method of claim 113, wherein the field comprises a long guard interval (GI) of about 800 ns.

121. An apparatus for wireless communications, comprising:

a receiver configured to receive a frame having a preamble portion and a data portion, wherein the preamble portion comprises a field indicating a length of useful data in the data portion and wherein the field comprises a plurality of replicated blocks, such that bits of one of the blocks are repeated in each of the blocks; and

a processing system configured to decode the data portion based on the field.

122. The apparatus of claim 121, wherein the field comprises a Very High Throughput Signal B (VHT-SIG-B) field.

123. The apparatus of claim 121, wherein the receiver is configured to receive the frame over a channel, wherein a bandwidth of the channel is about 80 MHz, and wherein the field comprises four blocks with the same 29 pre-coded bits repeated in each of the blocks.

124. The apparatus of claim 121, wherein the receiver is configured to receive the frame over a channel, wherein a bandwidth of the channel is about 160 MHz, and wherein the field comprises eight blocks with the same 29 pre-coded bits repeated in each of the blocks.

125. The apparatus of claim 121, wherein the receiver is configured to receive the frame over a channel, wherein a bandwidth of the channel is about 40 MHz, and wherein the field uses about 114 subcarriers.

126. The apparatus of claim 121, wherein the data portion comprises another field used for scrambler initialization and wherein the other field comprises a cyclic redundancy check (CRC) associated with the field indicating the length of the useful data.

127. The apparatus of claim 121, wherein the processing system is configured to stop the decoding after reaching an end of the useful data based on the length of the useful data.

128. The apparatus of claim 121, wherein the field comprises a long guard interval (GI) of about 800 ns.

129. An apparatus for wireless communications, comprising:

means for receiving a frame having a preamble portion and a data portion, wherein the preamble portion comprises a field indicating a length of useful data in the data portion and wherein the field comprises a plurality of replicated blocks, such that bits of one of the blocks are repeated in each of the blocks; and

means for decoding the data portion based on the field.

130. The apparatus of claim 129, wherein the field comprises a Very High Throughput Signal B (VHT-SIG-B) field.

131. The apparatus of claim 129, wherein the receiving comprises receiving the frame over a channel, wherein a bandwidth of the channel is about 80 MHz, and wherein the field comprises four blocks with the same 29 pre-coded bits repeated in each of the blocks.

132. The apparatus of claim 129, wherein the receiving comprises receiving the frame over a channel, wherein a bandwidth of the channel is about 160 MHz, and wherein the field comprises eight blocks with the same 29 pre-coded bits repeated in each of the blocks.

133. The apparatus of claim 129, wherein the receiving comprises receiving the frame over a channel, wherein a bandwidth of the channel is about 40 MHz, and wherein the field uses about 114 subcarriers.

134. The apparatus of claim 129, wherein the data portion comprises another field used for scrambler initialization and wherein the other field comprises a cyclic redundancy check (CRC) associated with the field indicating the length of the useful data.

135. The apparatus of claim 129, wherein the means for decoding is configured to stop the decoding after reaching an end of the useful data based on the length of the useful data.

136. The apparatus of claim 129, wherein the field comprises a long guard interval (GI) of about 800 ns.

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

receive a frame having a preamble portion and a data portion, wherein the preamble portion comprises a field indicating a length of useful data in the data portion and wherein the field comprises a plurality of replicated blocks, such that bits of one of the blocks are repeated in each of the blocks; and

decode the data portion based on the field.

138. The computer-program product of claim 137, wherein the field comprises a Very High Throughput Signal B (VHT-SIG-B) field.

139. The computer-program product of claim 137, wherein the instructions are executable to receive the frame by receiving the frame over a channel, wherein a bandwidth of the channel is about 80 MHz, and wherein the field comprises four blocks with the same 29 pre-coded bits repeated in each of the blocks.

140. The computer-program product of claim 137, wherein the instructions are executable to receive the frame by receiving the frame over a channel, wherein a bandwidth of the channel is about 160 MHz, and wherein the field comprises eight blocks with the same 29 pre-coded bits repeated in each of the blocks.

141. The computer-program product of claim 137, wherein the instructions are executable to receive the frame by receiving the frame over a channel, wherein a bandwidth of the channel is about 40 MHz, and wherein the field uses about 114 subcarriers.

142. The computer-program product of claim 137, wherein the data portion comprises another field used for scrambler initialization and wherein the other field comprises a cyclic redundancy check (CRC) associated with the field indicating the length of the useful data.

143. The computer-program product of claim 137, further comprising instructions executable to stop the decoding after reaching an end of the useful data based on the length of the useful data.

144. The computer-program product of claim 137, wherein the field comprises a long guard interval (GI) of about 800 ns.