Abstract:Automatic modulation recognition is crucial in wireless communications. With the development of deep learning technologies, researchers have applied them to radio signal modulation recognition, showing superior performance compared to traditional methods. However, purely data-driven approaches face several limitations, such as dependence on large-scale data, sensitivity to channel environment variations, and high computational complexity. To overcome these limitations, this paper investigated the integration of classical signal processing with deep learning. By leveraging classical signal processing techniques to guide and refine deep learning models, the performance in challenging scenarios, such as data heterogeneity, small sample sizes, low signal-to-noise ratios, multipath channels, open set and lightweight conditions, was enhanced. The results demonstrate that deep learning methods, when combined with classical signal processing, significantly improve the performance and reliability of modulation recognition in complex scenarios. Additionally, key challenges for future research were discussed, including the selection of appropriate signal processing algorithms, innovations in computational paradigms, and the interpretability of deep learning models. Addressing these challenges will further promote the synergy between classical signal processing and deep learning in radio modulation recognition, pointing out new directions for future intelligent radio signal processing.