Patent ID: 7181676

Claim:
A method of decoding in layers data received in a communication system, comprising: receiving a codeword containing a plurality of elements, the codeword encoded according to a low density parity check code represented by a parity check matrix having rows and columns, each of the plurality of elements associated with a column of the parity check matrix, the columns of the parity check matrix corresponding to input nodes and the rows of the parity check matrix corresponding to parity check sums; dividing the rows of at least one column of the parity check matrix into groups; separately processing each of at least some of the groups by performing a sequence of operations comprising: for each row of the group, subtracting a previous check node value from a probability value for each input node contributing to the parity check sum for that row; generating a new check node value for that row using the result of the subtracting step; and for each input node contributing to the parity check sum for that row, updating a probability value using the new check node value and the result of the subtracting step; and then combining the updated probability values of the at least one column from each of the separately processed groups.