Multiple input hardware reuse using LDPC codes
View Patent ↗A network controller receives data substantially simultaneously from multiple client nodes. The network controller assigns to each client node one or more sub-carriers of an orthogonal frequency-division multiplexing access frequency spectrum. The client nodes transmit substantially simultaneously M LDPC codewords that are encoded in a parity check matrix so that the number of rows m′ depend on the code rate and are mapped on its assigned sub-carriers. The network controller computes a bit log-likelihood ratio for each received bit of the codewords and arranges the bit LLR by codeword to align with an equivalent parity check matrix. The network controller decodes the codewords with the equivalent parity check matrix.
1. A non-transitory computer readable media having instructions stored thereon that, when executed by a processor, causes the processor to decode data received from a plurality of transmitting nodes, the instructions comprising logic for:
assigning to each transmitting node one or more sub-carriers of an Orthogonal frequency-division multiplexing access (OFDMA) frequency spectrum;
receiving M codewords from the transmitting nodes, wherein the codewords are low-density parity-check (LDPC) codewords and are encoded in a parity check matrix so that a number of rows m′ depend on a code rate and are mapped on the assigned sub-carrier;
computing a bit log-likelihood ratio for each received bit of the codewords and arranging the bit LLR by codeword to align with an equivalent parity check matrix;
decoding the codewords with the equivalent parity check matrix;
wherein each of the codewords are M times shorter than an Orthogonal frequency-division multiplexing (OFDM) LDPC codeword.
2. The non-transitory computer readable media of claim 1 , wherein the encoded parity check matrix comprises:
H
ofdma
=
[
h
1
,
1
h
1
,
2
h
1
,
3
…
h
1
,
n
′
h
2
,
1
h
2
,
2
h
2
,
3
…
h
2
,
n
′
h
3
,
1
h
3
,
2
h
3
,
3
…
h
3
,
n
′
⋮
⋮
⋮
⋱
⋮
h
m
′
,
1
h
m
′
,
2
h
m
′
,
3
…
h
m
′
,
n
′
]
.
3. The non-transitory computer readable media of claim 1 , wherein the equivalent parity check, matrix comprises:
H
eq
=
[
Q
1
,
1
Q
1
,
2
Q
1
,
3
…
Q
1
,
n
′
Q
2
,
1
Q
2
,
2
Q
2
,
3
…
Q
2
,
n
′
Q
3
,
1
Q
3
,
2
Q
3
,
3
…
Q
3
,
n
′
⋮
⋮
⋮
⋱
⋮
Q
m
′
,
1
Q
m
′
,
2
Q
m
′
,
3
…
Q
m
′
,
n
′
]
;
wherein
Q
i
,
j
=
[
h
i
,
j
(
1
)
0
0
…
0
0
h
i
,
j
(
2
)
0
…
0
0
0
h
i
,
j
(
3
)
…
0
⋮
⋮
⋮
⋰
⋮
0
0
0
…
h
i
,
j
(
M
)
]
and
each h i,j sub-matrix is P′×P′ and P′=P/M, wherein P is the expansion factor for the OFDM parity check matrix and P′ is the expansion factor for the OFDMA parity check matrix.
4. The non-transitory computer readable media of claim 1 , wherein the equivalent parity cheek matrix comprises:
H
eq
=
[
Q
1
,
1
Q
1
,
2
Q
1
,
3
…
Q
1
,
n
′
Q
2
,
1
Q
2
,
2
Q
2
,
3
…
Q
2
,
n
′
Q
3
,
1
Q
3
,
2
Q
3
,
3
…
Q
3
,
n
′
⋮
⋮
⋮
⋱
⋮
Q
m
′
,
1
Q
m
′
,
2
Q
m
′
,
3
…
Q
m
′
,
n
′
]
;
wherein
Q
i
,
j
=
[
h
i
,
j
(
1
)
0
0
…
0
0
h
i
,
j
(
2
)
0
…
0
0
0
h
i
,
j
(
3
)
…
0
⋮
⋮
⋮
⋰
⋮
0
0
0
…
h
i
,
j
(
M
)
]
and
each h i,j (k) sub-matrix is P (k) ×P (k) and Q ij is P t ×P t and a total expansion factor is
P
t
=
∑
i
=
1
M
P
(
i
)
≤
P
,
where P (i) is an expansion factor of the i th codeword, P is the expansion factor for the OFDM parity check matrix.
5. The non-transitory computer readable media of claim 4 , wherein each h i,j (k) sub-matrix is square, but wherein the dimension of each sub-matrix is independent of the other on-diagonal sub-matrices.
6. The non-transitory computer readable media of claim 4 , wherein each zero sub-matrix is has a width equal to the width of the sub-matrix in the diagonal that is in that same row and a length equal to the length of the sub-matrix in the diagonal that is in that same column.
7. A system for decoding data from a plurality of transmitting nodes, the system comprising:
means for assigning to each transmitting nodes one or more sub-carriers of an Orthogonal frequency-division multiplexing access (OFDMA) frequency spectrum;
means for receiving M codewords from the transmitting nodes, wherein the codewords are low-density parity-check (LDPC) codewords and are encoded in a parity check matrix so that a number of rows m′ depend on a code rate and are mapped on the assigned sub-carrier;
means for computing a hit log-likelihood ratio for each received hit of the codewords and arranging the bit LLR by codeword to align with an equivalent parity check matrix;
means for decoding the codewords with the equivalent parity check matrix; and
wherein each of the codewords are M times shorter than an Orthogonal frequency-division multiplexing (OFDM) LDPC codeword.
8. A network node comprising:
a transceiver;
a demodulator coupled to the transceiver; and
a decoder coupled to the demodulator, wherein the decoder is adapted to:
assign to each of a plurality of transmitting nodes one or more sub-carriers of an Orthogonal frequency-division multiplexing access (ODFMA) frequency spectrum;
receive M codewords from the transmitting nodes, wherein the codewords are low-density parity-check (LDPC) codewords and are encoded in a parity check matrix so that a number of rows m′ depend on a code rate and are mapped on the assigned sub-carrier;
compute a bit log-likelihood ratio for each received hit of the codewords and arranging the bit LLR by codeword to align with an equivalent parity check matrix;
decode the codewords with the equivalent parity check matrix; and
wherein each of the codewords are M times shorter than an Orthogonal frequency-division multiplexing (OFDM) LDPC codeword.
9. The network node of claim 8 , wherein the encoded parity check matrix comprises:
H
ofdma
=
[
h
1
,
1
h
1
,
2
h
1
,
3
…
h
1
,
n
′
h
2
,
1
h
2
,
2
h
2
,
3
…
h
2
,
n
′
h
3
,
1
h
3
,
2
h
3
,
3
…
h
3
,
n
′
⋮
⋮
⋮
⋱
⋮
h
m
′
,
1
h
m
′
,
2
h
m
′
,
3
…
h
m
′
,
n
′
]
.
10. The network node of claim 8 , wherein the equivalent parity check matrix comprises:
H
eq
=
[
Q
1
,
1
Q
1
,
2
Q
1
,
3
…
Q
1
,
n
′
Q
2
,
1
Q
2
,
2
Q
2
,
3
…
Q
2
,
n
′
Q
3
,
1
Q
3
,
2
Q
3
,
3
…
Q
3
,
n
′
⋮
⋮
⋮
⋱
⋮
Q
m
′
,
1
Q
m
′
,
2
Q
m
′
,
3
…
Q
m
′
,
n
′
]
;
wherein
Q
i
,
j
=
[
h
i
,
j
(
1
)
0
0
…
0
0
h
i
,
j
(
2
)
0
…
0
0
0
h
i
,
j
(
3
)
…
0
⋮
⋮
⋮
⋱
⋮
0
0
0
…
h
i
,
j
(
M
)
]
and
each h i,j sub-matrix is P′×P′ and P′=P/M, wherein P is the expansion factor for the OFDM parity check matrix and P′ is the expansion factor for the OFDMA parity check matrix.
11. The network node of claim 8 , wherein the equivalent parity check matrix comprises:
H
eq
=
[
Q
1
,
1
Q
1
,
2
Q
1
,
3
…
Q
1
,
n
′
Q
2
,
1
Q
2
,
2
Q
2
,
3
…
Q
3
,
n
′
Q
3
,
1
Q
3
,
2
Q
3
,
3
…
Q
3
,
n
′
⋮
⋮
⋮
⋱
⋮
Q
m
′
,
1
Q
m
′
,
2
Q
m
′
,
3
…
Q
m
′
,
n
′
]
;
wherein
Q
i
,
j
=
[
h
i
,
j
(
1
)
0
0
…
0
0
h
i
,
j
(
2
)
0
…
0
0
0
h
i
,
j
(
3
)
…
0
⋮
⋮
⋮
⋱
⋮
0
0
0
…
h
i
,
j
(
M
)
]
and
each h i,j (k) sub-matrix is P (k) ×P (k) and Q ij is P t ×P t and a total expansion factor is
P
t
=
∑
i
=
1
M
P
(
i
)
≤
P
,
where P (i) is an expansion factor of the i th codeword, P is the expansion factor for the OFDM parity check matrix.
12. The network node of claim 11 , wherein each h i,j (k) sub-matrix is square, but wherein the dimension of each sub-matrix is independent of the other on-diagonal sub-matrices.
13. The network node of claim 12 , wherein each zero sub-matrix is has a width equal to the width of the sub-matrix in the diagonal that is in that same row and a length equal to the length of the sub-matrix in the diagonal that is in that same column.
14. A non-transitory computer readable media having instructions stored thereon that, when executed by a processor, causes the processor to decode data received from a plurality of transmitting nodes, the instructions comprising logic for:
assigning to each transmitting nodes one or more sub-carriers of an Orthogonal frequency-division multiplexing access (OFDMA) frequency spectrum;
receiving M codewords from the transmitting nodes, wherein the codewords are low-density parity-check (LDPC) codewords and are encoded in a parity check matrix so that a number of rows m′ depend on a code rate and are mapped on the assigned sub-carrier;
computing a bit log-likelihood ratio for each received bit of the codewords and arranging the bit LLR by codeword to align with an equivalent parity cheek matrix;
decoding the codewords with the equivalent parity check matrix;
wherein the equivalent parity check matrix comprises:
H
eq
=
[
Q
1
,
1
Q
1
,
2
Q
1
,
3
…
Q
1
,
n
′
Q
2
,
1
Q
2
,
2
Q
2
,
3
…
Q
2
,
n
′
Q
3
,
1
Q
3
,
2
Q
3
,
3
…
Q
3
,
n
′
⋮
⋮
⋮
⋱
⋮
Q
m
′
,
1
Q
m
′
,
2
Q
m
′
,
3
…
Q
m
′
,
n
′
]
;
wherein
Q
i
,
j
=
[
h
i
,
j
(
1
)
0
0
…
0
0
h
i
,
j
(
2
)
0
…
0
0
0
h
i
,
j
(
3
)
…
0
⋮
⋮
⋮
⋱
⋮
0
0
0
…
h
i
,
j
(
M
)
]
and
each h i,j (k) sub-matrix is P (k) ×P (k) and Q ij is P t ×P t and a total expansion factor is
P
t
=
∑
i
=
1
M
P
(
i
)
≤
P
,
where P (i) is an expansion factor of the i th codeword, P is the expansion factor for the Orthogonal frequency-division multiplexing (OFDM) parity check matrix; and
wherein each h i,j (k) sub-matrix is square, but wherein the dimension of each sub-matrix is independent of the other on-diagonal sub-matrices.
15. The non-transitory computer readable media of claim 14 , wherein the encoded parity check matrix comprises:
H
ofdma
=
[
h
1
,
1
h
1
,
2
h
1
,
3
…
h
1
,
n
′
h
2
,
1
h
2
,
2
h
2
,
3
…
h
2
,
n
′
h
3
,
1
h
3
,
2
h
3
,
3
…
h
3
,
n
′
⋮
⋮
⋮
⋱
⋮
h
m
′
,
1
h
m
′
,
2
h
m
′
,
3
…
h
m
′
,
n
′
]
.
16. The non-transitory computer readable media of claim 14 , wherein each zero sub-matrix is has a width equal to the width of the sub-matrix in the diagonal that is in that same row and a length equal to the length of the sub-matrix in the diagonal that is in that same column.
17. A network node comprising:
a transceiver;
a demodulator coupled to the transceiver; and
a decoder coupled to the demodulator, wherein the decoder is adapted to:
assign to each of a plurality of transmitting nodes one or more sub-carriers of an Orthogonal frequency-division multiplexing access (ODFMA) frequency spectrum;
receive M codewords from the transmitting nodes, wherein the codewords are low-density parity-check (LDPC) codewords and are encoded in a parity cheek matrix so that a number of rows m′ depend on a code rate and are mapped on the assigned sub-carrier;
compute a bit log-likelihood ratio for each received hit of the codewords and arranging the bit LLR by codeword to align with an equivalent parity check matrix;
decode the codewords with the equivalent parity check matrix;
wherein the equivalent parity check matrix comprises:
H
eq
=
[
Q
1
,
1
Q
1
,
2
Q
1
,
3
…
Q
1
,
n
′
Q
2
,
1
Q
2
,
2
Q
2
,
3
…
Q
2
,
n
′
Q
3
,
1
Q
3
,
2
Q
3
,
3
…
Q
3
,
n
′
⋮
⋮
⋮
⋱
⋮
Q
m
′
,
1
Q
m
′
,
2
Q
m
′
,
3
…
Q
m
′
,
n
′
]
;
wherein
Q
i
,
j
=
[
h
i
,
j
(
1
)
0
0
…
0
0
h
i
,
j
(
2
)
0
…
0
0
0
h
i
,
j
(
3
)
…
0
⋮
⋮
⋮
⋰
⋮
0
0
0
…
h
i
,
j
(
M
)
]
and
each h i,j (k) sub-matrix is P (k) ×P (k) and Q ij is P t ×P t and a total expansion factor is
P
t
=
∑
i
=
1
M
P
(
i
)
≤
P
,
where P (i) is an expansion factor of the i th codeword, P is the expansion factor for the Orthogonal frequency-division multiplexing (OFDM) parity cheek matrix; and
wherein each h i,j (k) sub-matrix is square, but wherein the dimension of each sub-matrix is independent of the other on-diagonal sub-matrices.
18. The network node of claim 17 , wherein each zero sub-matrix is has a width equal to the width of the sub-matrix in the diagonal that is in that same row and a length equal to the length of the sub-matrix in the diagonal that is in that same column.
19. A system for decoding data from a plurality of transmitting nodes, the system comprising:
means for assigning to each transmitting nodes one or more sub-carriers of an orthogonal frequency-division multiplexing access (OFDMA) frequency spectrum;
means for receiving M codewords from the transmitting nodes, wherein the codewords are low-density parity-check (LDPC) codewords and are encoded in a parity check matrix so that a number of rows m′ depend on a code rate and are mapped on the assigned sub-carrier;
means for computing a bit log-likelihood ratio for each received bit of the codewords and arranging the bit LLR by codeword to align with an equivalent parity check matrix;
means for decoding the codewords with the equivalent parity check matrix; and
wherein the equivalent parity check matrix comprises:
H
eq
=
[
Q
1
,
1
Q
1
,
2
Q
1
,
3
…
Q
1
,
n
′
Q
2
,
1
Q
2
,
2
Q
2
,
3
…
Q
2
,
n
′
Q
3
,
1
Q
3
,
2
Q
3
,
3
…
Q
3
,
n
′
⋮
⋮
⋮
⋰
⋮
Q
m
′
,
1
Q
m
′
,
2
Q
m
′
,
3
…
Q
m
′
,
n
′
]
;
wherein
Q
i
,
j
=
[
h
i
,
j
(
1
)
0
0
…
0
0
h
i
,
j
(
2
)
0
…
0
0
0
h
i
,
j
(
3
)
…
0
⋮
⋮
⋮
⋱
⋮
0
0
0
…
h
i
,
j
(
M
)
]
and
each h i,j (k) sub-matrix is P (k) ×P (k) and Q ij is P t ×P t and a total expansion factor is
P
t
=
∑
i
=
1
M
P
(
i
)
≤
P
,
where P (i) is an expansion factor of the i th codeword, P is the expansion factor for the orthogonal frequency-division multiplexing (OFDM) parity check matrix; and
wherein each h i,j (k) sub-matrix is square, but wherein the dimension of each sub-matrix is independent of the other on-diagonal sub-matrices.