Important Bits Prefix M-Ary Quadrature Amplitude Modulation for Semantic Communications
Haonan Lu, Rui Meng, Xiaodong Xu, Ying Liu, Ping Zhang, Dusit Tao Niyato · IEEE Wireless Communications Letters · 2026
M-ary Quadrature Amplitude Modulation (MQAM) is a commonly used channel modulation technology in wireless communication systems. To achieve dedicated channel modulation for semantic communication (SemCom), we propose an Important Bits Prefix MQAM (IBP-MQAM) scheme and derive its approximate expression of important symbol error rate (ISER) and unimportant symbol error rate (USER). By extracting and quantifying text semantics using Dynamic Proximal Policy Optimization (DPPO) and Latent Dirichlet Allocation (LDA), we verify that IBP-MQAM achieves improved performance over MQAM in SemCom scenarios and further analyze the effects of key system parameters.