Semantic Communication on Digital Wireless Communication System

Semantic communication is an effective technological approach for the integration of intelligence and communication, enabling more efficient and context-aware data transmission. In this paper, we propose a bit-conversion-based semantic communication transmission framework to ensure the compatibility with existing wireless system. Specifically, a series of physical-layer processing modules in the end-to-end transmission are designed. Additionally, we develop a semantic communication simulator to implement and evaluate this framework. To optimize the performance of this framework, we introduce a novel physical-layer metric, termed Integer Error Rate (IER), which provides a more suitable evaluation criterion for semantic communication compared to the conventional Bit Error Rate (BER). On the basis of IER, a minimum Manhattan distance constellation mapping scheme is proposed, which can improve the transmission quality of semantic communication under the same BER condition. Furthermore, we propose a hybrid Joint Source-Channel Coding (JSCC) and Separate Source-Channel Coding (SSCC) transmission scheme. This scheme decouples the semantic quantization output from the modulation order by segmenting the bits to be transmitted. Simulation results demonstrate that the hybrid JSCC/SSCC transmission scheme can improve the semantic performance such as Peak Signal-to-Noise Ratio (PSNR) at the low Signal-to-Noise Ratio (SNR) environment while reducing bandwidth usage by up to 50% compared to the benchmark scheme.