Reconfigurable Shuffle Network Design in LDPC Decoders
ASAP '06 Proceedings of the IEEE 17th International Conference on Application-specific Systems, Architectures and Processors
IEEE Transactions on Very Large Scale Integration (VLSI) Systems
LDPC block and convolutional codes based on circulant matrices
IEEE Transactions on Information Theory
QSN: a simple circular-shift network for reconfigurable quasi-cyclic LDPC decoders
IEEE Transactions on Circuits and Systems II: Express Briefs
Flexible LDPC decoder architectures
VLSI Design - Special issue on Flexible Radio Design: Trends and Challenges in Digital Baseband Implementation
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In this paper, we propose an efficient low-complexity switch network design for reconfigurable low-density parity-check (LDPC) decoders. The proposed architecture leads to significant reductions in hardware complexity. Since the structured quasi-cyclic (QC) LDPC codes for most modern wireless communication systems include multiple code rates, various block lengths, and different sizes of submatrices, a reconfigurable LDPC decoder is desirable and the barrel shifter needs to be programmable. The Benes network cannot be optimized as the barrel shifter for a reconfigurable LDPC decoder when the input size of barrel shifter is not a power of 2. Also, it is not trivial to generate all the control signals on-the-fly for numerous 2 × 2 switches in the switch network. In this paper, a novel low-complexity switch network design is proposed, which can be used efficiently when the input size of barrel shifters is not a power of 2. Furthermore, we propose a novel algorithm to generate all the control signals, which can be implemented with a small size of lookup table (LUT) or a simple combination logic on-the-fly, using the properties that both the full-size switch network can be broken into two half-size switch networks and the barrel shifters for the structured QC LDPC decoders require only cyclic shifts. Compared with conventional Benes networks using a dedicated LUT or a complicated signal generating algorithm, the proposed architectures achieve significant hardware reductions in implementing the barrel shifters for reconfigurable LDPC decoders. In synthesis result using the TSMC 0.18-µm standard cell CMOS technology, the proposed switch network for a reconfigurable LDPC decoder of IEEE 802.16e and IEEE 802.11n can be implemented with an area of 0.772 mm2, which leads to a significant area reduction.