Encoder, transmitting apparatus, coding method and transmission method
Disclosed are an encoder, a transmitting device, a coding method and a transmission method with which the transmission amount is reduced and a deterioration in transmission efficiency is suppressed while improving reception quality when QC-LDPC or a like block coding is used. A puncture pattern setting unit searches for a puncture pattern for each integral multiple of the number of columns or for each divisor of the number of columns of a sub block matrix that forms a check matrix (H) of a QC-LDPC code, and a puncture unit (data reduction unit) switches the puncture pattern for each integral multiple of the number of columns or for each divisor of the number of columns of the sub block matrix that forms the check matrix of the QC-LDPC code.
1. An encoder comprising:
a coding section that generates coded sequence s that is made up of z×n b bits and satisfies equation 1-1, equation 1-2 and equation 1-3 for information bit sequence u; and
a selecting section that selects either of a puncturing pattern for removing a column group that corresponds to consecutive y bits and a puncturing pattern for not removing a column group that corresponds to the consecutive y bits as a puncturing pattern having a unit of divisor y of a number of columns z for each y bits from a first bit to a z×n b -th bit,
a puncturing section that determines bits to be removed for each y bits based on the selected puncturing pattern, removes the bits determined to be removed from the z×n b bits configuring the coded sequence s to form a transmission information bit sequence, and outputs the transmission information bit sequence, wherein
the selecting section selects a column group from a plurality of column groups having column weight of 3 in a matrix that corresponds to the information bit sequence u, the matrix includes a plurality of column groups having column weight of equal to or greater than 3, and the matrix is included in a parity check matrix H of an low density parity check code, and
the selecting section selects two column groups in a matrix that corresponds to a parity bit sequence and is included in the parity check matrix H of the low density parity check code:
[1]
GH T =0 (Equation 1-1)
s T =Gu T (Equation 1-2)
Hs= 0 (Equation 1-3)
where H is a parity check matrix of an low density parity check code of z×m b rows and z×n b columns configured by arranging submatrixes of z rows and z columns in m b rows and n b columns, G is a generator matrix holding a relationship of equation 1-1 with parity check matrix H of the low density parity check code and the coded sequence s is a coded sequence made up of z×n b bits.
2. The encoder according to claim 1 , wherein the parity check matrix H of the low density parity check code is defined by equation 2:
[2]
(
Equation
2
)
H
=
[
P
0
,
0
P
0
,
1
P
0
,
2
⋯
P
0
,
n
b
-
2
P
0
,
n
b
-
1
P
1
,
0
P
1
,
1
P
1
,
2
⋯
P
1
,
n
b
-
2
P
1
,
n
b
-
1
P
2
,
0
P
2
,
1
P
2
,
2
⋯
P
2
,
n
b
-
2
P
2
,
n
b
-
1
⋮
⋮
⋮
⋯
⋮
⋮
P
m
b
-
1
,
0
P
m
b
-
1
,
1
P
m
b
-
1
,
2
⋯
P
m
b
-
1
,
n
b
-
2
P
m
b
-
1
,
n
b
-
1
]
where P i,j is a cyclic permutation matrix of a unit matrix of z rows and z columns or zero matrix of z rows and z columns.
3. The encoder according to claim 2 , wherein the low density parity check code is a quasi cyclic low density parity check code.
4. A transmitting apparatus comprising a transmitting section that is provided with the encoder according to claim 1 and transmits the transmission information bit sequence.
5. A coding method comprising the steps of:
generating coded sequence s that is made up of z×n b bits and satisfies equation 3-1, equation 3-2 and equation 3-3 for information bit sequence u; and
selecting either of a puncturing pattern for removing a column group that corresponds to consecutive y bits and a puncturing pattern for not removing a column group that corresponds to the consecutive y bits as a puncturing pattern having a unit of divisor y of a number of columns z for each y bits from a first bit to a z×n b -th bit,
determining bits to be removed for each y bits based on the selected puncturing pattern,
removing the bits determined to be removed from the z×n b bits configuring the coded sequence s to form a transmission information bit sequence, and
outputting the transmission information bit sequence, wherein
the selecting includes selecting a column group from a plurality of column groups having column weight of 3 in a matrix that corresponds to the information bit sequence u, the matrix includes a plurality of column groups having column weight of equal to or greater than 3, and the matrix is included in a parity check matrix H of an low density parity check code, and
selecting two column groups in a matrix that corresponds to a parity bit sequence and is included in the parity check matrix H of the low density parity check code:
[3]
GH T =0 (Equation 3-1)
s T =Gu T (Equation 3-2)
Hs= 0 (Equation 3-3)
where H is a parity check matrix of an low density parity check code of z×m b rows and z×n b columns configured by arranging submatrixes of z rows and z columns in m b rows and n b columns, G is a generator matrix holding a relationship of equation 3-1 with parity check matrix H of the low density parity check code and the coded sequence s is a coded sequence made up of z×n b bits.
6. The coding method according to claim 5 , wherein the parity check matrix H of the low density parity check code is defined by equation 4:
[4]
(
Equation
4
)
H
=
[
P
0
,
0
P
0
,
1
P
0
,
2
⋯
P
0
,
n
b
-
2
P
0
,
n
b
-
1
P
1
,
0
P
1
,
1
P
1
,
2
⋯
P
1
,
n
b
-
2
P
1
,
n
b
-
1
P
2
,
0
P
2
,
1
P
2
,
2
⋯
P
2
,
n
b
-
2
P
2
,
n
b
-
1
⋮
⋮
⋮
⋯
⋮
⋮
P
m
b
-
1
,
0
P
m
b
-
1
,
1
P
m
b
-
1
,
2
⋯
P
m
b
-
1
,
n
b
-
2
P
m
b
-
1
,
n
b
-
1
]
7. The coding method according to claim 6 , wherein the low density parity check code is a quasi cyclic low density parity check code.
8. A transmission method comprising the coding method according to claim 5 for transmitting the transmission information bit sequence.