A device for determining a coded modulation scheme, said coded modulation scheme being defined by a modulation scheme, a modulation mapping, and a one parity check non-binary LDPC code defined by a non-binary parity-check equation constructed over a finite field, a non-binary parity-check equation being represented by non-zero coefficients, said modulation scheme being based on a joint optimization of the coefficients of the parity-check equation and of the modulation mapping, the modulation scheme being represented by a set of symbols, wherein said device comprises: - a calculation unit configured to determine at least two candidate sets, a candidate set comprising: - a candidate modulation mapping, a modulation mapping consisting of a labeling of each symbol in the set of symbols with corresponding values in a set of values in said field, and - one candidate parity-check equation, the candidate parity-check equation defining a non-binary LDPC code, the candidate parity-check equation providing codeword vectors, wherein each candidate set is associated with one or more metrics, each metric being evaluated for an Euclidean distance of a defined value and representing the number of distinct pairs of codeword vectors satisfying the candidate parity check equation that are associated with said Euclidean distance; and - a selection unit configured to select a candidate set among said candidate sets according to an optimization criterion applied to said one or more metrics, wherein the candidate modulation mappings of said at least two candidate sets comprise Gray mapping. - a calculation unit configured to determine at least two candidate sets, a candidate set comprising: - a candidate modulation mapping, a modulation mapping consisting of a labeling of each symbol in the set of symbols with corresponding values in a set of values in said field, and - one candidate parity-check equation, the candidate parity-check equation defining a non-binary LDPC code, the candidate parity-check equation providing codeword vectors, wherein each candidate set is associated with one or more metrics, each metric being evaluated for an Euclidean distance of a defined value and representing the number of distinct pairs of codeword vectors satisfying the candidate parity check equation that are associated with said Euclidean distance; and - a selection unit configured to select a candidate set among said candidate sets according to an optimization criterion applied to said one or more metrics, wherein the candidate modulation mappings of said at least two candidate sets comprise Gray mapping. - a candidate modulation mapping, a modulation mapping consisting of a labeling of each symbol in the set of symbols with corresponding values in a set of values in said field, and - one candidate parity-check equation, the candidate parity-check equation defining a non-binary LDPC code, the candidate parity-check equation providing codeword vectors, wherein each candidate set is associated with one or more metrics, each metric being evaluated for an Euclidean distance of a defined value and representing the number of distinct pairs of codeword vectors satisfying the candidate parity check equation that are associated with said Euclidean distance; and - a selection unit configured to select a candidate set among said candidate sets according to an optimization criterion applied to said one or more metrics, wherein the candidate modulation mappings of said at least two candidate sets comprise Gray mapping.