Minimum Sum Algorithm Decoder for LDPC Nonregular Parity Check Matrix in BPSK System
Yi Hua Chen, Jue Hsuan Hsiao, Zong Yi Saio, Hua Ting Syu · 2015
Referring to the approximate lower triangular low-density parity-check code check matrix of the IEEE P802.11n™/D1.04 (Part 11: Wireless Local Area Network Medium Access Control and Physical Layer speciflcations), this study established a decoder based on LabVIEW program language on a single program architecture that can adjust the transmission end to generate diverse codeword patterns, including three subblock sizes (27, 54, and 81bit) and four code rates (1/2, 2/3, 3/4, and 5/6). Combined with the minimum sum algorithm (MSA), the decoder completed decoding tasks by changing the check node and variable node structures on the basis of the selected subblock size and code rate. In addition to providing an introduction on the decoding mechanism of the MSA and completing decoding program optimization and analysis of bit error rate(BER) performance curves, this study applied the LabVIEW program to simulate the BER of the ratio of energy per bit to the spectral noise density (Eb/No) at each point from 0 to 10dB, when subblock sizes (27, 54, and 81bit) were combined with code rates (1/2, 2/3, and 5/6) operating in an additive white Gaussian noise channel environment. The error rate performance curve diagrams of two studies were referenced (regular weight (3, 6) and 802.11n irregular subblock size 27bit combined with code rate 5/6) and compared with the simulation outcome yielded in this study. The result showed that the subblock size did not afiect the error rate, but the code rates substantially afiected the error rates. When the code rate was set to 1/2, the error correction performance of the irregular check matrix was considerably higher than that of the regular check matrix.