Novel construction of quasi-cyclic low-density parity-check codes with variable code rates for cloud data storage systems

This paper proposed a novel method for constructing quasi-cyclic low-density parity-check (QC-LDPC) codes of medium to high code rates that can be applied in cloud data storage systems, requiring better error correction capabilities. The novelty of this method lies in the construction of sparse base matrices, using a girth greater than 4 that can then be expanded with a lift factor to produce high code rate QC-LDPC codes. Investigations revealed that the proposed large-sized QC-LDPC codes with high code rates displayed low encoding complexities and provided a low bit error rate (BER) of 10(-10) at 3.5 dB E-b/N-0 than conventional LDPC codes, which showed a BER of 10(-7) at 3 dB E-b/N-0. Subsequently, implementation of the proposed QC-LDPC code in a software-defined radio, using the NI USRP 2920 hardware platform, was conducted. As a result, a BER of 10(-6) at 4.2 dB E-b/N-0 was achieved. Then, the performance of the proposed codes based on their encoding-decoding speeds and storage overhead was investigated when applied to a cloud data storage (GCP). Our results revealed that the proposed codes required much less time for encoding and decoding (of data files having a 10 MB size) and produced less storage overhead than the conventional LDPC and Reed-Solomon codes.