Hardware-efficient low density parity check code for digital communications

Decoder circuitry for decoding a received signal stream that was encoded according to a low density parity check (LDPC) code;

• wherein the LDPC code is represented by a macro matrix having zero-valued and non-zero-valued entries arranged in block rows and block columns and in which each zero-valued entry corresponds to a p×p zero-valued matrix and each non-zero-valued entry corresponds to a p×p permutation matrix that has at most a single “1” entry in each row and each column and “0” entries elsewhere to define a parity check matrix, wherein the block columns of the macro matrix are grouped so that at most one column has a “1” entry in any row, and wherein the columns of the parity check matrix correspond to input nodes and the rows of the parity check matrix correspond to parity check sums;
• the circuitry comprising:
• a check node memory for storing estimates of check node values associated with each of the input nodes over each of a plurality of parity check sums of the LDPC code;
• a parallel adder coupled to the check node memory, for combining a group of check node values associated with a row of the parity check matrix with probability value estimates for input nodes corresponding to the group of check node values, to produce a plurality of extrinsic estimates;
• a parity check update circuit, for updating the estimates of the check node values using the extrinsic estimates, each updated estimate of the check node values associated with an input node;
• a plurality of bit update circuits, each for updating a probability value estimate corresponding to an input node;
• routing circuitry, for routing each updated estimate of the check node values to the one of the plurality of bit update circuits associated with its corresponding input node;
• and
• rerouting circuitry, for routing each updated probability value from the bit update circuits to the parallel adder.

A method of transmitting an encoded datastream, comprising:

• defining a portion of a data stream to be encoded;
• applying a block code to the defined datastream portion to produce an encoded datastream portion, the block code corresponding to a matrix multiplication of the defined datastream portion by a generator matrix, wherein the generator matrix is defined from a low density parity check (LDPC) code represented by a macro matrix having zero-valued and non-zero-valued entries arranged in block rows and block columns and in which each zero-valued entry corresponds to a p×p zero-valued matrix and each non-zero-valued entry corresponds to a p×p permutation matrix that has at most a single “1” entry in each row and each column and “0” entries elsewhere to define a parity check matrix, wherein the block columns of the macro matrix are grouped so that at most one column has a “1” entry in any row, and wherein the columns of the parity check matrix correspond to input nodes and the rows of the parity check matrix correspond to parity check sums;
• and
• transmitting a signal corresponding to the encoded datastream portion over a transmission channel.