Low-Density Parity-Check Codes for Industrial Wireless Applications
Abstract
In recent years, advances in wireless technologies have led to a surge in the adoption of wireless networks for industrial control, and automation purposes. Existing standards are often based upon IEEE 802.15.4, which specifies automatic repeat request (ARQ) for packet retransmission. Alone, ARQ can lead to large transmission delays in the presence of adverse channel conditions. Forward error correction (FEC) as an alternative solution is tempting. However, if decoding errors persist, no provision is given for packet retransmission. Therefore, a type-II hybrid ARQ (HARQ) mechanism that utilizes pseudo-randomly punctured low-density parity-check (LDPC) codes is considered. The viability of LDPC codes in the proposed type-II HARQ system is fully explored by utilizing a range of short block lengths and varying decoder types. Hard-decision Gallager-A and soft and soft-decision sum-product decoding are considered. Additionally, an improved hard-decision decoder based on a modified peeling algorithm in tandem with the Gallager-A algorithm is proposed. The throughput and complexity of both decoder types are explored. The complexity is presented in terms of worst case clock cycles. The results show that short LDPC codes perform better than RS codes and Turbo codes with respect to bit error rate. As well, the improved hard-decision decoder greatly improves the bit error rate performance of hard-decision decoding in the presence of pseudo-random puncturing. The HARQ throughput performance of short codelengths surpasses that of longer codes, on a per frame basis, regardless of decoder type. Finally, the complexity of soft-decision decoding is shown to fall below hard-decision decoding for a range of SNR values.
Description
Keywords
Engineering--Electronics and Electrical
Citation
Rizopoulos, K. A. (2017). Low-Density Parity-Check Codes for Industrial Wireless Applications (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/26795