Methods and apparatus for WLAN transmission
In a method for generating a PHY data unit for transmission via a communication channel, a modulation scheme is selected from a plurality of modulation schemes, information bits are encoded to generate encoded data using one or more encoders, and an interleaving parameter N COL is selected using the selected modulation scheme. N COL varies for different modulation schemes. The encoded data is interleaved, which includes entering the encoded data into N ROW rows and reading the encoded data out in N COL columns. The payload information of the PHY data unit is modulated according to the modulation scheme, and a plurality of OFDM symbols is formed based on the modulated payload information.
1. A method, implemented in a communication device, for generating a physical layer (PHY) data unit for transmission via a communication channel, the method comprising:
selecting, in the communication device, a modulation scheme from a plurality of modulation schemes;
encoding, in the communication device, information bits to generate encoded data using one or more encoders;
selecting, in the communication device, a number of spatial streams N SS ;
parsing, in the communication device, the encoded data into the number of spatial streams N SS ;
selecting, in the communication device, a first interleaving parameter N COL ;
selecting, in the communication device, a second interleaving parameter N ROT using the selected number of spatial streams N SS , wherein N ROT varies for different numbers of spatial streams;
interleaving, in the communication device, the encoded data, including entering the encoded data into a matrix having an integer number of rows equal to N ROW and an integer number of columns equal to N COL , reading the encoded data out in the N COL columns, and applying a frequency rotation r according to
r= ( j−f*N ROT *N BPSCS ( i SS )) mod N CBPSS ( i SS )
where i SS is a spatial stream index, N CBPSS (i SS ) is a number of coded bits per symbol for an i SS -th spatial stream, N BPSCS (i SS ) is a number of coded bits per subcarrier for the i SS -th spatial stream, j=0, 1, . . . , N CBPSS (i SS )−1, and f is an integer that varies based on the spatial stream index i SS ;
modulating, in the communication device, payload information of the PHY data unit according to the modulation scheme, wherein the payload information includes the interleaved encoded data; and
forming, in the communication device, a plurality of orthogonal frequency division multiplex (OFDM) symbols based on the modulated payload information.
2. The method of claim 1 , further comprising:
selecting, in the communication device, the parameter N ROW using the selected modulation scheme, wherein N ROW is the same for some modulation schemes.
3. The method of claim 1 , wherein N ROW *N COL =N Tone * N BPSCS (i SS ) holds for all i SS , where N Tone is a number of data tones, and where N BPSCS (i SS ) is a number of coded bits per subcarrier for an i SS th spatial stream.
4. The method of claim 1 , wherein N ROT =(N Tone /N SS )+C, where N Tone is a number of data tones, and where C is either zero or a non-zero integer constant.
5. The method of claim 1 , wherein:
encoding information bits to generate encoded data using one or more encoders includes encoding the information bits to generate binary convolutional code (BCC) encoded data using one or more BCC encoders; and
interleaving the encoded data includes interleaving the BCC encoded data.
6. The method of claim 1 , wherein f is an integer function of the spatial stream index i SS and the number of spatial streams N SS .
7. A physical layer (PHY) apparatus for generating a PHY data unit for transmission via a communication channel, the PHY apparatus comprising:
a memory configured to store indicators of a plurality of modulation schemes,
wherein the PHY apparatus is configured to (i) select a modulation scheme from the plurality of modulation schemes, (ii) select a first interleaving parameter N COL (iii) select a number of spatial streams N SS and (iv) select a second interleaving parameter N ROT using the selected number of spatial streams N SS , wherein N ROT is an integer that varies for different numbers of spatial streams,
wherein the PHY apparatus further comprises
one or more encoders configured to encode information bits to generate encoded data,
a stream parser configured to parse the encoded data into the number of spatial streams N SS ,
an interleaver configured to interleave the encoded data, including entering the encoded data into a matrix having an integer number of rows equal to N Row and an integer number of columns equal to N COL , reading the encoded data out in N COL columns, and applying a frequency rotation r according to
r= ( j−f*N ROT *N BPSCS ( i SS )) mod N CBPSS ( i SS )
where i SS is a spatial stream index, N CBPSS (i SS ) is a number of coded bits per symbol for an i SS -th spatial stream, N BPSCS (i SS ) is a number of coded bits per subcarrier for the i SS -th spatial stream, j=0, 1, . . . , N CBPSS (i SS )−1, and f is an integer that varies based on the spatial stream index i SS , and
one or more modulators configured to modulate the encoded data from the interleaver according to the selected modulation scheme, and
wherein the PHY apparatus is configured to form a plurality of OFDM symbols based on the modulated encoded data.
8. The PHY apparatus of claim 7 , wherein the PHY apparatus is configured to select the parameter N ROW using the selected modulation scheme, and wherein N ROW is the same for some modulation schemes.
9. The PHY apparatus of claim 7 , wherein N ROW *N COL =N Tone *N BPSCS (i SS ) holds for all i ss , where N Tone is a number of data tones, and where N BPSCS (i SS ) is a number of coded bits per subcarrier for an i SS th spatial stream.
10. The PHY apparatus of claim 7 , wherein N ROT =(N Tone / N SS )+C, where N Tone is a number of data tones, and where C is either zero or a non-zero integer constant.
11. The PHY apparatus of claim 7 , wherein the one or more encoders are binary convolutional code (BCC) encoders.
12. The PHY apparatus of claim 7 , wherein f is an integer function of the spatial stream index i SS and the number of spatial streams N SS .
13. A tangible, non-transitory, computer-readable medium storing instructions that, when executed by one or more processors, cause the one or more processors to:
select a modulation scheme from a plurality of modulation schemes;
encode information bits to generate encoded data using one or more encoders;
select a number of spatial streams N SS ;
parse the encoded data into the number of spatial streams N SS ;
select a first interleaving parameter N COL ; select a second interleaving parameter N ROT using the selected number of spatial streams N SS , wherein N ROT is an integer that varies for different numbers of spatial streams;
interleave the encoded data, including entering the encoded data into a matrix having an integer number of rows equal to N Row and an integer number of columns equal to N COL , reading the encoded data out in N COL columns, and applying a frequency rotation r according to
r= ( j−f*N ROT *N BPSCS ( i SS )) mod N CBPSS ( i SS )
where i SS is a spatial stream index, N BPSCS (i SS ) is a number of coded bits per symbol for an i SS -th spatial stream, N BPSCS (i SS ) is a number of coded bits per subcarrier for the i SS -th spatial stream, j=0, 1, . . . , N CBPSS (i SS )−1, and f is an integer that varies based on the spatial stream index i SS ;
modulate the payload information of the PHY data unit according to the modulation scheme; and
form a plurality of orthogonal frequency division multiplex (OFDM) symbols based on the modulated payload information.
14. The tangible, non-transitory, computer-readable medium of claim 13 , wherein the computer-readable medium further stores instructions that, when executed by one or more processors, cause the one or more processors to:
select the parameter N ROW using the selected modulation scheme, wherein N ROW is the same for some modulation schemes.
15. The tangible, non-transitory, computer-readable medium of claim 13 , wherein N ROW *N COL =N Tone *N BPSCS (i SS ) holds for all i SS , where N Tone is a number of data tones, and where N BPSCS (i SS ) is a number of coded bits per subcarrier for an i SS th spatial stream.
16. The tangible, non-transitory, computer-readable medium of claim 13 , wherein N ROT =(N Tone /N SS )+C, where N Tone is a number of data tones, and where C is either zero or a non-zero integer constant.
17. The tangible, non-transitory, computer-readable medium of claim 13 , wherein f is an integer function of the spatial stream index i SS and the number of spatial streams N SS .