A fully-overlapped multi-mode QC-LDPC decoder architecture for mobile WiMAX applications

A fully-overlapped multi-mode QC-LDPC decoder architecture, adopting improved TDMP algorithm, is presented in this paper. With symmetrical four-stage pipelining, block column and row permutations, nonzero sub-matrix reordering, sum memory odd-even partition, and read-write bypass, two phases are fully overlapped and each phase scans nonzero sub-matrices one by one in block row-wise order without access conflicts to sum memories. The sum memories store not only variable node sums but also prior messages. In this case, it saves an additional FIFO of 13 440 bits. The decoder attains 248-287 Mb/s at 150 MHz and 15 iterations.