1. A method for decoding a noisy codeword received from a communication channel as the result of transmitting a LDPC codeword having a first number (N) of codeword bits which comprise a second number (K) of information bits and a third number (M) of parity check bits, wherein the product of the LDPC codeword and a predetermined M×N parity check matrix is zero, wherein the parity check matrix represents a bipartite graph comprising N variable nodes connected to M check nodes via edges according to matrix elements of the parity check matrix, the method comprising: receiving the noisy codeword via said communication channel; calculating, for each of said N codeword bits of said LDPC codeword, an a-priori estimate (Qv) that the codeword bit has a predetermined value from the received noisy codeword and from predetermined parameters of said communication channel; storing the calculated estimates (Qv) for each variable node of said bipartite graph corresponding to a codeword bit in a memory as initialization variable node values; and iteratively calculating messages on all edges of said bipartite graph according to a serial schedule; wherein in each iteration, for each check node of said bipartite graph, for all neighboring variable nodes connected to said check node, input messages to said check node from said neighboring variable nodes and output messages from said check node to said neighboring variable nodes are calculated by means of a message passing computation rule.