High Efficiency Orthogonal Frequency Division Multiplexing (OFDM) Physical Layer (PHY)

• US 20150349995A1
• Filed: 06/02/2015
• Published: 12/03/2015
• Est. Priority Date: 06/02/2014
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Marvell World Trade Limited (Marvell Technology Group Limited)
• Inventors: ZHANG, Hongyuan, SUN, Yakun, CAO, Rui, LOU, Hui-Ling, XU, Mingguang
• Granted Patent: US 9,832,059 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04L 1/0042 Encoding specially adapted to other signal generation operation, e.g. in order to reduce transmit distortions, jitter, or to improve signal shape H04L1/0067 takes precedence
• CPC Class Codes: H04L 1/0059 Convolutional codes
• CPC Class Codes: H04L 1/007 Unequal error protection for format H04L1/0078; for codes per se H03M13/35
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/0643 block codes
• CPC Class Codes: H04L 27/26025 Numerology, i.e. varying one or more of symbol duration, subcarrier spacing, Fourier transform size, sampling rate or down-clocking allocating sub-channels of the transmission path H04L5/003
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 27/2627 Modulators
• CPC Class Codes: H04L 27/2675 Pilot or known symbols
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

In a method for generating a data unit for transmission via a communication channel, the data unit conforming to a first communication protocol, one or more orthogonal frequency division multiplexing (OFDM) symbols of the data unit are generated. Each OFDM symbol of the one or more OFDM symbols (i) occupies a first bandwidth, (ii) is generated with a first tone spacing, and (iii) includes a set of pilot tones. The first tone spacing is a fraction 1/N of a second tone spacing, the second tone spacing defined for the first bandwidth by a second communication protocol. The set of pilot tones includes a same number of pilot tones as defined for the first bandwidth by the second communication protocol. The data unit is generated to include the one or more OFDM symbols in a data portion of the data unit.

Claims

1. A method for generating a data unit for transmission via a communication channel, the data unit conforming to a first communication protocol, the method comprising:

generating, at a communication device, one or more orthogonal frequency division multiplexing (OFDM) symbols, wherein each OFDM symbol of the one or more OFDM symbols (i) occupies a first bandwidth, (ii) is generated with a first tone spacing, and (iii) includes a set of pilot tones, wherein

the first tone spacing is a fraction 1/N of a second tone spacing, the second tone spacing defined for the first bandwidth by a second communication protocol, wherein N is a positive integer greater than one, and

the set of pilot tones includes a same number of pilot tones as defined for the first bandwidth by the second communication protocol; and

generating, at the communication device, the data unit to include the one or more OFDM symbols in a data portion of the data unit.

2. The method of claim 1, wherein generating the one or more OFDM symbols includes:

encoding information bits using one or more binary convolution code (BCC) encoders to generate coded bits;

interleaving the coded bits using a first set of interleaving parameters, wherein interleaving parameters in the first set of interleaving parameters are scaled versions of corresponding interleaving parameters in a second set of interleaving parameters, the second set of interleaving parameters defined for the first bandwidth by the second communication protocol;

mapping the interleaved coded bits onto a plurality of constellation points; and

forming the one or more OFDM symbols based on the plurality of constellation points.

3. The method of claim 2, wherein the first set of interleaving parameters includes N_col, N_row, and N_rot, wherein:

N_col of the first set of interleaving parameters is N_col of the second set of interleaving parameters multiplied by square root of N and adjusted based on a total number of data tones in each OFDM symbol;

N_row of the first set of interleaving parameters is N_row of the second set of interleaving parameters multiplied by square root of N; and

N_rot of the first set of interleaving parameters is N_rot of the second set of interleaving parameters multiplied by N.

4. The method of claim 1, wherein generating the one or more OFDM symbols includes:

encoding information bits using one or more low density parity check (LDPC) encoders to generate coded bits;

mapping blocks of coded bits onto constellation points; and

mapping consecutively generated constellation points onto non-consecutive tones using a tone mapping distance D₁, wherein the tone mapping distance D₁ is a scaled version of corresponding tone mapping distance D₂ defined for the first bandwidth by the second communication protocol, wherein D₁=N*D₂.

5. The method of claim 1, wherein each OFDM symbol of the one or more OFDM symbols further includes a first set of guard tones, and wherein the first set of guard tones includes a greater number of guard tones than a number of guard tones in a second set of guard tones, the second set of guard tones defined for the first bandwidth by the second communication protocol.

6. The method of claim 1, wherein the first bandwidth is 80 MHz, and wherein each OFDM symbol of the one or more OFDM symbols includes 1024 tones.

7. The method of claim 1, wherein the integer N is equal to four.

8. The method of claim 1, wherein generating the data unit further comprises generating the data unit to further include an extension signal field that follows the one or more OFDM symbols, wherein the extension signal field is generated using the second tone spacing defined for the first bandwidth by the second communication protocol.

9. An apparatus, comprising:

a network interface device having one or more integrated circuits configured to

generate one or more orthogonal frequency division multiplexing (OFDM) symbols for a data unit that conforms to a first communication protocol, wherein each OFDM symbol of the one or more OFDM symbols (i) occupies a first bandwidth, (ii) are generated with a first tone spacing, and (iii) includes a set of pilot tones, wherein

the first tone spacing is a fraction 1/N of a second tone spacing, the second tone spacing defined for the first bandwidth by a second communication protocol, wherein N is a positive integer greater than one, and

the set of pilot tones includes a same number of pilot tones as defined for the first bandwidth by the second communication protocol, and

generate the data unit to include the one or more OFDM symbols in a data portion of the data unit.

10. The apparatus of claim 9, wherein the one or more integrated circuits are further configured to:

encode information bits using one or more binary convolution code (BCC) encoders to generate coded bits to be included in the data unit;

interleave the coded bits using a first set of interleaving parameters, wherein interleaving parameters in the first set of interleaving parameters are scaled versions of corresponding interleaving parameters in a second set of interleaving parameters, the second set of interleaving parameters defined for the first bandwidth by the second communication protocol;

map the interleaved coded bits onto a plurality of constellation points; and

form the one or more OFDM symbols based on the plurality of constellation points.

11. The apparatus of claim 10, wherein the first set of interleaving parameters includes N_col, N_row, and N_rot, wherein:

N_col of the first set of interleaving parameters is N_col of the second set of interleaving parameters multiplied by square root of N and adjusted based on a total number of data tones in each OFDM symbol;

N_row of the first set of interleaving parameters is N_row of the second set of interleaving parameters multiplied by square root of N; and

N_rot of the first set of interleaving parameters is N_rot of the second set of interleaving parameters multiplied by N.

12. The apparatus of claim 9, wherein the one or more integrated circuits are configured to:

encode information bits using one or more low density parity check (LDPC) encoders to generate coded bits;

map blocks of coded bits onto constellation points; and

map consecutively generated constellation points onto non-consecutive tones such using a tone mapping distance D₁, wherein the tone mapping distance D₁ is a scaled version of corresponding tone mapping distance D₂ defined for the first bandwidth by the second communication protocol, wherein D₁=N*D₂.

13. The apparatus of claim 9, wherein the one or more integrated circuits are configured to generate each OFDM symbol of the one or more OFDM symbols to further include a first set of guard tones, and wherein the first set of guard tones includes a greater number of guard tones than a number of guard tones in a second set of guard tones, the second set of guard tones defined for the first bandwidth by the second communication protocol.

14. The apparatus of claim 9, wherein the first bandwidth is 80 MHz, and wherein each OFDM symbol of the one or more OFDM tones includes 1024 tones.

15. The apparatus of claim 9, wherein the integer N is equal to four.

16. The apparatus of claim 9, wherein the one or more integrated circuits are further configured to generate the data unit to include (i) the one or more OFDM symbols and (ii) an extension signal field that follows the one or more OFDM symbols, wherein the extension signal field is generated using the second tone spacing defined for the first bandwidth by the second communication protocol.

17. A method for generating a data unit for transmission via a communication channel, the method comprising:

generating, at a communication device, one or more orthogonal frequency division multiplexing (OFDM) symbols, including generating the one or more OFDM symbols based on a first tone map corresponding to a first number of OFDM tones or based on a second tone map corresponding to a second number of OFDM tones, wherein the first tone map is used if the data unit is to be transmitted in a first transmission mode corresponding to a first bandwidth or a second transmission mode corresponding to a second bandwidth, wherein the second bandwidth is twice of the first bandwidth, and

the second tone map used if the data unit is to be transmitted in a third transmission mode corresponding to a third bandwidth or a fourth transmission mode corresponding to a fourth bandwidth, wherein the third bandwidth is twice of the second bandwidth and the fourth bandwidth is twice of the third bandwidth; and

generating the data unit to include the one or more OFDM symbols in a data portion of the data unit.

18. The method of claim 17, wherein (i) the first bandwidth is 20 MHz, (ii) the second bandwidth is 40 MHz, (iii) the third bandwidth is 80 MHz, and (iv) the fourth bandwidth is 160 MHz.

19. The method of claim 18, wherein (i) the first number of OFDM tones is 256 tones, (ii) the second number of OFDM tones is 512 tones, (iii) the third number of OFDM tones is 1024 tones, and (iv) the fourth number of OFDM tones is 2048 tones.

20. An apparatus, comprising:

a network interface device having one or more integrated circuits configured to

generate one or more orthogonal frequency division multiplexing (OFDM) symbols, including generating the one or more OFDM symbols based on a first tone map corresponding to a first number of OFDM tones or based on a second tone map corresponding to a second number of OFDM tones, wherein

the first tone map is used if the data unit is to be transmitted in a first transmission mode corresponding to a first bandwidth or a second transmission mode corresponding to a second bandwidth, wherein the second bandwidth is twice of the first bandwidth, and

the second tone map used if the data unit is to be transmitted in a third transmission mode corresponding to a third bandwidth or a fourth transmission mode corresponding to a fourth bandwidth, wherein the third bandwidth is twice of the second bandwidth and the fourth bandwidth is twice of the third bandwidth, and

generate the data unit to include the one or more OFDM symbols in a data portion of the data unit.

21. The apparatus of claim 20, wherein (i) the first bandwidth is 20 MHz, (ii) the second bandwidth is 40 MHz, (iii) the third bandwidth is 80 MHz, and (iv) the fourth bandwidth is 160 MHz.

22. The apparatus of claim 20, wherein (i) the first number of OFDM tones is 256 tones, (ii) the second number of OFDM tones is 512 tones, (iii) the third number of OFDM tones is 1024 tones, and (iv) the fourth number of OFDM tones is 2048 tones.