A Network-Efficient Nonbinary QC-LDPC Decoder Architecture

Abstract

Nonbinary low-density parity-check (LDPC) codes are of great interest due to their better performance cover binary ones when the code length is moderate. However, the cost of decoder implementation for these LDPC codes is still very high. In this paper, a low-complexity VLSI architecture for nonbinary LDPC decoders is presented. By exploiting the intrinsic shifting and symmetry properties of nonbinary quasi-cyclic LDPC (QC-LDPC) codes, significant reduction of memory size and routing complexity can be achieved. These unique features lead to two network-efficient decoder architectures for Class-I and Class-II nonbinary QC-LDPC codes, respectively. Comparison results with the state-of-the-art designs show that for the code example of the 64-ary (1260, 630) rate-0.5 Class-I code, the proposed scheme can save up to 70.6% hardware required by switch network, which demonstrates the efficiency of the proposed technique. The proposed design for the 32-ary (992, 496) rate-0.5 Class-II code can achieve a 93.8% switch network complexity reduction compared with conventional approaches. Furthermore, with the help of a generator for possible solution sequences, both forward and backward steps can be eliminated to offer processing convenience of check node unit (CNU) blocks. Results show the proposed 32-ary (992, 496) rate-0.5 Class-II decoder can achieve 4.47 Mb/s decoding throughput at a clock speed of 150 MHz.

Challenges and some new directions in channel coding

“…Several studies on VLSI implementation of non binary decoders based on the previous algorithms have been presented in literature [48], [49], [50], [51], [52], [53], [54]. The results of such studies confirm that all non binary decoders require complexity growing with the size of the alphabet.…”

Efficient high throughput decoding architecture for non-binary LDPC codes

“…Lin et al [14], presented a parallel architecture to benefit variable and check node processing units. In [15], VLSI architecture was designed for nonbinary LDPC decoder. In this approach, symmetric properties and intrinsic shifting of QC-LDPC codes are manipulated to decrease the difficulties in routing as well as to reduce the area of memory.…”