A method of encoding an information word to generate a low-density parity-check, LDPC, codeword and of modulating the LDPC codeword for transmission via a channel using a LDPC code in a communication system including a parity-check matrix extractor, a shortening pattern applier, an LDPC encoder, and a modulator; said LDPC code's parity-check matrix having a length of N 1, an information part with an information length K 1, and a parity part with a parity length of ( N 1 -K 1), said K 1 columns in said information part being grouped in 20 column groups, where each column group comprises M 1 columns, where N 1 = 16200, K 1 = 7200, and M 1 = 360,said LDPC codeword having a length equal to N 1, having K 1 information bits corresponding to said information part of said LDPC code, and ( N 1 -K 1) parity bits corresponding to said parity part of said LDPC code, said information part having a structure defined by: R i, j k = R i, j − 1 k + q mod N 1 − K 1, k = 1, 2,..., D i, i = 1,..., K 1 / M 1, j = 1,..., M 1 − 1 where: i = index indicating i th column group; j = index indicating j th column in a column group; q = N 1 − K 1 / M 1; D i = a degree, i.e. number of non-zero entries, of a 0 th column in each i th column group; R i, 0 1, R i, 0 2,..., R i, 0 D i = positions of rows with a value of 1 in a 0 th column in each i th column group; and R i, j k k = 1, 2,..., D i = positions of rows with a value of 1 in a j th column in an i th column group, the method comprising: extracting information on an LDPC code's parity-check matrix; determining a value of a parameter K 2 where K 2 is information length of a shortened LDPC codeword to be obtained by shortening the LDPC codeword; for an integer m = ⌊ 7200 − K 2 360 ⌋, where 528≤ K 2 <7200, inserting bits having a value of 0 in the information word in positions corresponding to m column groups π, π,..., and π( m -1), wherein π, π,..., and π( m -1) is taken from the following table with 20 ordered column groups π, π,..., and π for a 16 quadrature amplitude modulation, QAM, modulation scheme: π π π π π π π π π π 18 17 16 15 14 13 12 11 4 10 π π π π π π π π π π 9 8 7 3 2 1 6 5 19 0 LDPC-encoding the information word thus obtained to generate said LDPC codeword; performing 16 QAM modulation. i = index indicating i th column group; j = index indicating j th column in a column group; D i = a degree, i.e. number of non-zero entries, of a 0 th column in each i th column group; R i, 0 1, R i, 0 2,..., R i, 0 D i = positions of rows with a value of 1 in a 0 th column in each i th column group; and R i, j k k = 1, 2,..., D i = positions of rows with a value of 1 in a j th column in an i th column group, extracting information on an LDPC code's parity-check matrix; determining a value of a parameter K 2 where K 2 is information length of a shortened LDPC codeword to be obtained by shortening the LDPC codeword; for an integer m = ⌊ 7200 − K 2 360 ⌋, where 528≤ K 2 <7200, inserting bits having a value of 0 in the information word in positions corresponding to m column groups π, π,..., and π( m -1), wherein π, π,..., and π( m -1) is taken from the following table with 20 ordered column groups π, π,..., and π for a 16 quadrature amplitude modulation, QAM, modulation scheme: π π π π π π π π π π 18 17 16 15 14 13 12 11 4 10 π π π π π π π π π π 9 8 7 3 2 1 6 5 19 0 LDPC-encoding the information word thus obtained to generate said LDPC codeword; performing 16 QAM modulation.