Parsing and encoding methods in a communication system
View Patent ↗In a method for generating a physical layer (PHY) data unit for transmission via a communication channel, a plurality of information bits to be included in the PHY data unit is received. A number of padding bits that need to be added to the information bits such that the information bits, after having been encoded, fill an integer number of orthogonal frequency division multiplexing (OFDM) symbols is determined. The number of padding bits is added to the information bits prior to encoding and the information bits are parsed to a number of encoders. The information bits are encoded to generate coded data bits. A last block of the data unit is encoded differently from the previous blocks. The PHY data unit to include the coded data bits is generated.
1. A method for generating a physical layer (PHY) data unit for transmission via a communication channel, the method comprising:
receiving a plurality of information bits to be included in the PHY data unit;
determining a number of padding bits that need to be added to the information bits such that the information bits, after having been encoded, fill an integer number of orthogonal frequency division multiplexing (OFDM) symbols;
adding the number of padding bits to the information bits prior to encoding;
parsing the information bits to a number of encoders;
encoding the information bits to generate coded data bits, including encoding a last punctured block corresponding to at least one encoder differently from previous punctured blocks corresponding to the at least one encoder; and
generating the PHY data unit to include the coded data bits.
2. The method according to claim 1 , wherein parsing the information bits to the number of encoders comprises assigning an unequal number of information bits to at least two of the encoders if the number of encoders is more than one.
3. The method according to claim 1 , wherein determining the number of padding bits comprises:
calculating a number of punctured blocks needed to fit the information bits according to
Z
=
⌈
(
8
L
+
N
service
+
N
tail
N
ES
)
N
R
⌉
,
calculating a number of OFDM symbols needed to fit the number of punctured blocks according to
N
SYM
=
⌈
ZD
R
N
CBPS
⌉
,
and calculating the number of padding bits according to
p
=
⌊
(
N
SYM
N
CBPS
)
D
R
⌋
N
R
-
(
8
L
+
N
service
+
N
tail
N
ES
)
,
wherein
L is a number of octets in the plurality of information bits,
N service is a number of service bits,
N tail is a number of tail bits,
N ES is a number of encoders,
N CBPS is a number of coded bits per OFDM symbol,
N R and D R are determined by a code rate of the one or more encoders R=N R /D R .
4. The method according to claim 3 , wherein encoding the last punctured block of the data unit comprises adding a number of additional padding bits to the last punctured block after encoding, wherein the number of additional padding bits is determined according to
q 1 =mod( N SYM N CBPS ,D R ).
5. The method according to claim 1 , wherein encoding the last punctured block of the at least one encoder differently from the previous punctured blocks of the at least one encoder comprises:
determining a number of residue bits corresponding to the last punctured block of the at least one encoder;
determining a number of information bits needed to generate the number of residue bits, wherein the number of information bits needed to generate the number of residue bits depends on a code rate of the one or more encoders;
encoding the last punctured block based on the number of residue bits.
6. The method according to claim 5 , wherein the number of residue bits is determined according to
N residue =mod( N SYM N CBPS ,D R ).
7. The method according to claim 6 , wherein determining the number of padding bits comprises calculating a number of OFDM symbols needed to fit the information bits according to
N
SYM
=
⌈
(
8
L
+
N
service
+
N
tail
N
ES
)
N
DBPS
⌉
,
and calculating the number of padding bits according to
p
=
⌊
(
N
SYM
N
CBPS
)
D
R
⌋
N
R
+
f
(
N
residue
,
R
)
-
(
8
L
+
N
service
+
N
tail
N
ES
)
,
wherein
L is a number of octets in the plurality of information bits,
N service is a number of service bits,
N tail is a number of tail bits,
N ES is a number of encoders,
N DBPS is a number of data bits per OFDM symbol,
N CBPS is a number of coded bits per OFDM symbol,
f(x, R) is the number of information bits needed to generate x bits for the code rate R.
8. The method according to claim 5 , wherein the number of residue bits is determined according to
N residue =mod( N SYM N CBPS ,N ES D R ).
9. The method according to claim 8 , wherein determining the number of padding bits comprises calculating a number of OFDM symbols needed to fit the information bits according to
N
SYM
=
⌈
(
8
L
+
N
service
+
N
tail
N
ES
)
N
DBPS
⌉
,
and
when N residue >2N ES , calculating the number of padding bits according to
p
=
⌊
(
N
SYM
N
CBPS
)
N
ES
D
R
⌋
N
R
N
ES
+
(
N
ES
f
(
⌊
N
residue
N
ES
⌋
)
+
mod
(
N
residue
,
N
ES
)
)
-
(
8
L
+
N
service
+
N
tail
N
ES
)
,
when N residue ≦2N ES , calculating the number of padding bits according to
p
=
⌊
(
N
SYM
N
CBPS
)
N
ES
D
R
⌋
N
R
N
ES
+
N
residue
2
-
(
8
L
+
N
service
+
N
tail
N
ES
)
,
wherein
L is a number of octets in the plurality of information bits,
N service is a number of service bits,
N tail is a number of tail bits,
N ES is a number of encoders,
N DBPS is a number of data bits per OFDM symbol,
N CBPS is a number of coded bits per OFDM symbol,
f(x, R) is the number of information bits needed to generate x bits for the code rate R.
10. An apparatus, comprising:
a network interface configured to
i) receive a plurality of information bits to be included in a physical layer (PHY) data unit;
ii) determine a number of padding bits that need to be added to the information bits such that the information bits, after having been encoded, fill an integer number of orthogonal frequency division multiplexing (OFDM) symbols; and
iii) add the number of padding bits to the information bits;
an encoder parser configured to parse the information bits to a number of encoders; and
one or more encoders configured to encode the information bits to generate coded data bits, including encoding a last punctured block corresponding to at least one encoder differently from previous punctured blocks corresponding to the at least one encoder; and
wherein the network interface is further configured to generate the PHY data unit to include the coded data bits.
11. The apparatus according to claim 10 , wherein the encoder parser is configured to assign an unequal number of information bits to at least two of the encoders if the number of encoders is more than one.
12. The apparatus according to claim 10 , wherein the network interface is configured to determine the number of padding bits by:
calculating a number of punctured blocks needed to fit the information bits according to
Z
=
⌈
(
8
L
+
N
service
+
N
tail
N
ES
)
N
R
⌉
,
calculating a number of OFDM symbols needed to fit the number of punctured blocks according to
N
SYM
=
⌈
ZD
R
N
CBPS
⌉
,
and calculating the number of padding bits according to
p
=
⌊
(
N
SYM
N
CBPS
)
D
R
⌋
N
R
-
(
8
L
+
N
service
+
N
tail
N
ES
)
,
wherein
L is a number of octets in the plurality of information bits,
N service is a number of service bits,
N tail is a number of tail bits,
N ES is a number of encoders,
N CBPS is a number of coded bits per OFDM symbol,
N R and D R are determined by a code rate of the one or more encoders R=N R /D R .
13. The apparatus according to claim 12 , wherein the network interface is configured to add a number of additional padding bits to the last punctured block after encoding, wherein the number of additional padding bits is determined according to
q 1 =mod( N SYM N CBPS ,D R ).
14. The apparatus according to claim 10 , wherein the network interface is configured to:
determine a number of residue bits corresponding to the last punctured block of the at least one encoder, and
determine a number of information bits needed to generate the number of residue bits, wherein the number of information bits needed to generate the number of residue bits depends on a code rate of the one or more encoders;
and wherein the one or more encoders are configured to encode the last punctured block based on the number of residue bits.
15. The apparatus according to claim 10 , wherein the network interface is configured to determine a number of residue bits according to
N residue =mod( N SYM N CBPS ,N R ).
16. The apparatus according to claim 15 , wherein the network interface is configured to determine the number of padding bits by calculating a number of OFDM symbols needed to fit the information bits according to
N
SYM
=
⌈
(
8
L
+
N
service
+
N
tail
N
ES
)
N
DBPS
⌉
,
and calculating the number of padding bits according to
p
=
⌊
(
N
SYM
N
CBPS
)
D
R
⌋
N
R
+
f
(
N
residue
,
R
)
-
(
8
L
+
N
service
+
N
tail
N
ES
)
,
wherein
L is a number of octets in the plurality of information bits,
N service is a number of service bits,
N tail is a number of tail bits,
N ES is a number of encoders,
N DBPS is a number of data bits per OFDM symbol,
N CBPS is a number of coded bits per OFDM symbol,
f(x, R) is the number of information bits needed to generate x bits for the code rate R.
17. The apparatus according to claim 16 , wherein the network interface is configured to determine the number of residue bits according to:
N residue =mod( N SYM N CBPS ,N ES D R ).
18. The apparatus according to claim 17 , wherein the network interface is configured to determine the number of padding bits by calculating a number of OFDM symbols needed to fit the information bits according to
N
SYM
=
⌈
(
8
L
+
N
service
+
N
tail
N
ES
)
N
DBPS
⌉
,
and
when N residue >2N ES , calculating the number of padding bits according to
p
=
⌊
(
N
SYM
N
CBPS
)
N
ES
D
R
⌋
N
R
N
ES
+
(
N
ES
f
(
⌊
N
residue
N
ES
⌋
)
+
mod
(
N
residue
,
N
ES
)
)
-
(
8
L
+
N
service
+
N
tail
N
ES
)
,
when N residue ≦2N ES , calculating the number of padding bits according to
p
=
⌊
(
N
SYM
N
CBPS
)
N
ES
D
R
⌋
N
R
N
ES
+
N
residue
2
-
(
8
L
+
N
service
+
N
tail
N
ES
)
,
wherein
L is a number of octets in the plurality of information bits,
N service is a number of service bits,
N tail is a number of tail bits,
N ES is a number of encoders,
N DBPS is a number of data bits per OFDM symbol,
N CBPS is a number of coded bits per OFDM symbol,
f(x, R) is the number of information bits needed to generate x bits for the code rate R.
19. A method for generating a physical layer (PHY) data unit for transmission via a communication channel, the method comprising:
receiving a plurality of information bits to be included in the PHY data unit;
adding a number of padding bits to the information bits prior to encoding, wherein the number of padding bits depends on a virtual number of coded bits per orthogonal frequency division multiplexing (OFDM) symbol, the virtual number of coded bits per OFDM symbol being less than a true number of coded bits per OFDM symbol;
parsing the information bits to a number of encoders;
encoding the information bits using the number of encoders to generate coded data bits;
adding a number of additional padding bits to each OFDM symbol after encoding, wherein the number of additional padding bits depends on the true number of coded bits per OFDM symbol; and
generating the PHY data unit to include the coded data bits.
20. The method according to claim 19 , wherein the virtual number of coded bits per symbol is determined by
N
CBPS
virtual
=
(
⌊
N
CBPS
N
R
N
ES
⌋
N
R
N
ES
)
,
wherein
N CBPS is a number of coded bits per OFDM symbol,
N ES is the number of encoders,
N R is determined by a code rate of the one or more encoders R=N R /D R .
21. The method according to claim 19 , wherein parsing the information bits to the number of encoders comprises assigning an unequal number of information bits to at least two of the encoders if the number of encoders is more than one.
22. The method according to claim 21 , wherein the virtual number of coded bits per symbol is determined by
N
CBPS
virtual
=
(
⌊
N
CBPS
N
R
⌋
N
R
)
,
wherein
N CBPS is a number of coded bits per OFDM symbol,
N R is determined by a code rate of the one or more encoders R=N R /D R .
23. An apparatus comprising:
a network interface configured to
i) receive a plurality of information bits to be included in a physical layer (PHY) data unit;
ii) add a number of padding bits to the information bits prior to encoding, wherein the number of padding bits depends on a virtual number of coded bits per orthogonal frequency division multiplexing (OFDM) symbol, the virtual number of coded bits per OFDM symbol being less than a true number of coded bits per OFDM symbol, and
iii) add a number of additional padding bits to each OFDM symbol after encoding, wherein the number of additional padding bits depends on the true number of coded bits per OFDM symbol;
an encoder parser configured to parse the information bits to a number of encoders; and
one or more encoders configured to encode the information to generate coded data bits, wherein the network interface is further configured to generate the PHY data unit to include the coded data bits.
24. The apparatus according to claim 23 , wherein the network interface is configured to determine the virtual number of coded bits per OFDM symbol according to
N
CBPS
virtual
=
(
⌊
N
CBPS
N
R
N
ES
⌋
N
R
N
ES
)
,
wherein
N CBPS is a number of coded bits per OFDM symbol,
N ES is the number of encoders,
N R is determined by a code rate of the one or more encoders R=N R /D R .
25. The apparatus according to claim 23 , wherein the encoder parser is configured to assign an unequal number of information bits to at least two of the encoders if the number of encoders is more than one.
26. The apparatus according to claim 25 , wherein the network interface is configured to determine the virtual number of coded bits per OFDM symbol according to
N
CBPS
virtual
=
(
⌊
N
CBPS
N
R
⌋
N
R
)
,
wherein
N CBPS is a number of coded bits per OFDM symbol,
N R is determined by a code rate of the one or more encoders R=N R /D R .