Physical layer frame format for long range WLAN

1. A method for generating a physical layer (PHY) data unit for transmission via a communication channel, wherein the communication channel includes a plurality of spatial streams, the method comprising:

generating a first preamble portion of the PHY data unit, wherein the first preamble portion includes one or more long training fields, and wherein at least one of the one or more long training fields includes at least pilot tones and non-pilot tones;

generating a data portion of the PHY data unit;

modulating the first preamble portion and the data portion to generate a plurality of orthogonal frequency division multiplexing (OFDM) symbols, wherein symbol duration of each OFDM symbol of the plurality of OFDM symbols is at least 8 μs;

generating the PHY data unit to include the plurality of OFDM symbols;

mapping the non-pilot tones to the plurality of spatial streams using a mapping matrix; and

mapping the pilot tones to the plurality of spatial streams using a column of the mapping matrix.

2. The method of claim 1 , wherein the column of the mapping matrix used to map the pilot tones to the multiple spatial streams is the first column of the mapping matrix.

3. The method of claim 1 , further comprising:

i) generating a second preamble portion and ii) modulating the second preamble portion using single carrier modulation;

and wherein generating the PHY data unit further comprises including the second preamble portion.

4. The method of claim 3 , wherein the second preamble portion includes a number of repetitions of a Barker code sequence.

5. The method of claim 3 , wherein the second preamble portion includes a number of repetitions of a Golay code sequence.

6. The method of claim 1 , further comprising generating an additional PHY data unit using a first clock signal having a first clock rate, wherein generating the PHY data unit comprises:

generating a second clock signal using the first clock signal, wherein the second clock signal has a second clock rate that is a fraction of the first clock rate, and

wherein the PHY data unit is generated using the second clock signal.

7. The method of claim 1 , wherein generating the PHY data unit includes:

generating the PHY data unit according to a first PHY format when the PHY data unit is to be transmitted in a regular mode, wherein the first PHY format corresponds to a first bandwidth; and

generating the PHY data unit according to a second PHY format when the PHY data unit is to be transmitted in an extended range mode, wherein the second PHY format corresponds to a second bandwidth;

wherein a preamble of the PHY data unit is modulated such that a receiving device can auto-detect whether the PHY data unit was transmitted at the first bandwidth or the second bandwidth.

8. The method of claim 7 , wherein generating the PHY data unit according to the first PHY format comprises generating orthogonal frequency division (OFDM) symbols of the PHY data unit using a Fast Fourier Transform of a first size, and wherein generating the PHY data unit according to the second PHY format comprises generating orthogonal frequency division (OFDM) symbols of the PHY data unit using a Fast Fourier Transform of a second size.

9. The method of claim 8 , wherein the second size is less than or equal to 32.

10. An apparatus comprising:

a medium access control (MAC) processing unit configured to perform medium access control functions; and

a physical layer (PHY) processing unit, coupled to the MAC processing unit, the PHY processing unit configured to:

generate a first preamble portion of a PHY data unit, wherein the first preamble portion includes one or more long training fields, and wherein at least one of the one or more long training fields includes at least pilot tones and non-pilot tones,

generate a data portion of the PHY data unit,

modulate the first preamble portion and the data portion using a plurality of orthogonal frequency division multiplexing (OFDM) symbols, wherein symbol duration of each OFDM symbol of the plurality of OFDM symbols is at least 8 μs,

generate the PHY data unit to include the plurality of OFDM symbols,

map the non-pilot tones to multiple spatial streams using a mapping matrix, and

map the pilot tones to multiple spatial streams using a column of the mapping matrix.

11. The apparatus of claim 10 , wherein the PHY processing unit is configured to map pilot tones to multiple spatial streams using the first column of the mapping matrix.

12. The apparatus of claim 10 , wherein the PHY processing unit is further configured to generate a second preamble portion, wherein the second preamble portion utilizes single carrier modulation and wherein the PHY processing unit is configured to include the second preamble portion in the PHY data unit.

13. The apparatus of claim 12 , wherein the second preamble portion includes a number of repetitions of a Barker code sequence.

14. The apparatus of claim 12 , wherein the second preamble portion includes a number of repetitions of a Golay code sequence.

15. The apparatus of claim 10 , wherein the PHY processing unit is further configured to

generate an additional PHY data unit using a first clock signal having a first clock rate, and

generate a second clock signal using the first clock signal, wherein the second clock signal has a second clock rate that is a fraction of the first clock rate, and

wherein the PHY data unit is generated using the second clock signal.

16. The apparatus of claim 10 , wherein the PHY processing unit is further configured to:

generate the PHY data unit according to a first PHY format if the PHY data unit is to be transmitted in a regular mode, wherein the first PHY format corresponds to a first bandwidth, and

generate the PHY data unit according to a second PHY format if the PHY data unit is to be transmitted in an extended range mode, wherein the second PHY format corresponds to a second bandwidth, and

modulate a preamble of the PHY data unit such that a receiving device can auto-detect whether the PHY data unit was transmitted at the first bandwidth or the second bandwidth.

17. The apparatus of claim 16 , wherein the PHY processing unit is configured to i) use a Fast Fourier Transform of a first size to generate the PHY data unit according to the first format and ii) use a Fast Fourier Transform of a second size to generate the PHY data unit according to the second PHY format.

18. The apparatus of claim 17 , wherein the second size is less than or equal to 32.