ИСТИНА

The present invention in particular provides a variable-length rate-adaptive quasi cyclic (QC) low density parity check (LDPC) code with linear time encoding and low error floor. To this end, the present invention provides a data encoding method, the method comprising the steps of receiving a user bits vector u; determining a parity bits vector p, wherein a vector с=(u,p) is a codeword satisfying a Type-I mZ x nZ parity-check matrix H=(H u ,H p ) with a quasi-cyclic mZ x mZ submatrix H p of circulant size Z, wherein the first left m - r circulant columns of H p have zero circulants above a main diagonal of H p , the remaining right r circulant columns have zero circulants in the first top m - r circulant rows of H p , and the remaining bottom r circulant rows of H p and the remaining right r circulant columns of H p form an rZ x rZ square quasi-cyclic submatrix A, wherein a polynomial representation of the submatrix A over the ring F 2 [x] has a determinant equal to a monomial x i , wherein 0 ≤ i, and 4 ≤ r ≤ m. The present invention also provides a data encoder, a communication device, a storage device and a computer program product comprising said method.