Multilevel Polar-Coded PAM-8 with MSB Shaping over Turbulent FSO Communication Link
Weiying Yang, Xiaoyu Liu, Zhiyang Liu, Shilin Xiao · 2023
Thanks to the flexibility and adaptability of polar codes, a Free-space Optical (FSO) communication scheme combining it with probabilistic shaping (PS) and pulse amplitude modulation (PAM) is proposed to achieve capacity improvement in atmospheric turbulence (AT) channels. The proposed scheme generates a non-uniform probability distribution PAM-8 transmission symbol by a multilevel polar-coded modulation (MLPC) method equipped with the most significant bit (MSB) level shaping precoder. Under the selected turbulence conditions, it provides up to 1.09dB theoretical shaping gain of capacity at the specified information rate (AIR) of 1.859 bit/channel use and 0.82dB performance gain in block error rate.