Power Allocation for Throughput Maximization in NOMA-Based Semantic Communication System

The integration of semantic communication (SemCom) with non-orthogonal multiple access (NOMA) presents a promising approach to enhance spectrum efficiency and system capacity. SemCom focuses on accurate meaning delivery with less bits, while NOMA enables simultaneous access for multiple users on the same frequency, maximizing resource utilization. However, power allocation in NOMA-based SemCom systems is quite challenging as it should accommodate not only channel conditions and interference management but also the characteristics of semantic information and service requirements. In this paper, we investigate the power allocation strategy for NOMA-based SemCom systems, with the aim to maximize system throughput in semantic unit (STU). Successive interference cancellation requirements and resource budgets are taken into account as the constraints. To address this problem, we propose a modified water filling-based algorithm enhancing both STU and fairness. Simulation results demonstrate the superiority of our proposed algorithm in terms of STU performance and fairness compared to two existing baseline strategies.