Semantic Communications with Discrete-time Analog Transmission: A PAPR Perspective
This addresses a practical implementation problem for semantic communication systems, but it is incremental as it builds on existing DeepJSCC methods.
The paper tackles the high peak-to-average power ratio (PAPR) issue in DeepJSCC-based semantic communications by applying three PAPR reduction techniques to image transmission, confirming that superior reconstruction performance can be retained while suppressing PAPR to acceptable levels.
Recent progress in deep learning (DL)-based joint source-channel coding (DeepJSCC) has led to a new paradigm of semantic communications. Two salient features of DeepJSCC-based semantic communications are the exploitation of semantic-aware features directly from the source signal, and the discrete-time analog transmission (DTAT) of these features. Compared with traditional digital communications, semantic communications with DeepJSCC provide superior reconstruction performance at the receiver and graceful degradation with diminishing channel quality, but also exhibit a large peak-to-average power ratio (PAPR) in the transmitted signal. An open question has been whether the gains of DeepJSCC come from the additional freedom brought by the high-PAPR continuous-amplitude signal. In this paper, we address this question by exploring three PAPR reduction techniques in the application of image transmission. We confirm that the superior image reconstruction performance of DeepJSCC-based semantic communications can be retained while the transmitted PAPR is suppressed to an acceptable level. This observation is an important step towards the implementation of DeepJSCC in practical semantic communication systems.