dvbs2ldpc - Low-density parity-check codes from DVB-S.2 standard
Syntax
H = dvbs2ldpc(r)
Description
H = dvbs2ldpc(r) returns
the parity-check matrix of the LDPC code with code rate r from
the DVB-S.2 standard. H is a sparse logical matrix.
Possible values for r are 1/4, 1/3, 2/5,
1/2, 3/5, 2/3, 3/4, 4/5, 5/6, 8/9, and 9/10. The block length of the
code is 64800.
The default parity-check matrix (32400-by-64800) corresponds
to an irregular LDPC code with the structure shown in the following
table.
| Row | Number
of 1s Per Row |
|---|
| 1 | 6 |
| 2 to 32400 | 7 |
| Column | Number
of 1s Per Column |
|---|
| 1 to 12960 | 8 |
| 12961 to 32400 | 3 |
Columns 32401 to 64800 form
a lower triangular matrix. Only the elements on its main diagonal
and the subdiagonal immediately below are 1s. This LDPC code is used
in conjunction with a BCH code in the Digital Video Broadcasting standard
DVB-S.2 to achieve a packet error rate below
at about 0.7 dB to 1 dB from
the Shannon limit.
Example
H = dvbs2ldpc(3/5);
spy(H); % Visualize the location of nonzero elements in H.
henc = fec.ldpcenc(H);
hdec = fec.ldpcdec(H);
See Also
fec.ldpcdec, fec.ldpcenc, spy
 | dpskmod | | encode |  |
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