Abstract: This paper researches the encoding and decoding performance of 5G-NR LPDC in troposcatter channel， because of the lack of research on fading channel, especially in the nonlinear environment of time-varying channels. The 5G-NR LDPC code is classified as a quasi-cyclic LDPC code. Compared with the traditional coding scheme, it can support a variety of code rates and code lengths through the construction of the basis matrix, which is easy to realize rate-adaptive. This paper proposes a modified layered normalized minimum sum decoding algorithm, by modifying the normalization factor, which is more suitable for scattering channels. The simulation results show that compared with the traditional decoding method, the proposed algorithm improves the decoding speed by 3 times, reduces the number of iterations and reduces the complexity; and the performance of the proposed algorithm is improved by about 1.3 dB and 0.6 dB, respectively, either at low or high bit rates when the bit error rate reaches 10-5 under 16-diversity.

Key words: fifth generation, low density parity code, scattering channel, normalized minimum sum, modified layered decoding algorithm