FIGS. 5A-5D illustrate the parity check matrices of four LDPC codes specified in 802.11ad with the rates of 1/2, 5/8, 3/4, and 13/16. In 802.11ad, each LDPC code has a common codeword length of 672 bits. The code rate K/N denotes that a K bits source word is encoded to an N bits codeword. With respect to the 802.11ad standard, the codeword length N is 672 bits. Therefore, for the code rates of 1/2, 5/8, 3/4, and 13/16, the sizes of the corresponding source word are 336 bits, 420 bits, 504 bits, and 546 bits, respectively.
FIG. 5E illustrates an example of the cyclic permutation submatrices P1 and P3 obtained from the Z×Z identity matrix P0. In FIG. 5E, Z=4. P1 is obtained by shifting the columns of P0 to the right by one element, and P3 obtained is obtained by shifting the columns of P0 to the right by three elements.
In FIG. 5A, submatrix with the value “0” represents P0, which is a 42×42 identity submatrix, and the first submatrix with the value “40” in FIG. 5A is obtained by shifting the columns of P0 to the right by 40 elements. Similarly, any non-zero value i submatrices Pi in FIGS. 5B-5D can also be obtained from the respective identity matrix P0.
