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We present a method to design high-throughput fully parallel low-density parity-check (LDPC) decoders. With our method, a decoder's longest wires are divided into several short wires with pipeline registers. Log-likelihood ratio messages transmitted along with these pipelined paths are thus sent over multiple clock cycles, and the decoder's critical path delay can be reduced while maintaining comparable bit error rate performance. The number of registers inserted into paths is estimated by using wiring information extracted from initial placement and routing information with a conventional LDPC decoder, and thus only necessary registers are inserted. Also, by inserting an even number of registers into the longer wires, two different codewords can be simultaneously decoded, which improves the throughput at a small penalty in area. We present our design flow as well as post-layout simulation results for several versions of a length-1024, (3,6)-regular LDPC code. Using our technique, we achieve a maximum uncoded throughput of 13.21 Gb/s with an energy consumption of 0.098 nJ per uncoded bit at E b/N0 = 5 dB. This represents a 28% increase in throughput, a 30% decrease in energy per bit, and a 1.6% increase in core area with respect to a conventional parallel LDPC decoder, using a 90-nm CMOS technology.
Very Large Scale Integration (VLSI) Systems, IEEE Transactions on (Volume:18 , Issue: 3 )
Date of Publication: March 2010