We consider distributed image transmission over a noisy multiple access channel (MAC) using deep joint source-channel coding (DeepJSCC). It is known that Shannon's separation theorem holds when transmitting independent sources over a MAC in the asymptotic infinite block length regime. However, we are interested in the practical finite block length regime, in which case separate source and channel coding is known to be suboptimal. We introduce a novel joint image compression and transmission scheme, where the devices send their compressed image representations in a non-orthogonal manner. While non-orthogonal multiple access (NOMA) is known to achieve the capacity region, to the best of our knowledge, non-orthogonal joint source channel coding (JSCC) scheme for practical systems has not been studied before. Through extensive experiments, we show significant improvements in terms of the quality of the reconstructed images compared to orthogonal transmission employing current DeepJSCC approaches particularly for low bandwidth ratios. We publicly share source code to facilitate further research and reproducibility.

翻译：我们研究了在噪声多址接入信道（MAC）上利用深度联合信源信道编码（DeepJSCC）实现分布式图像传输的问题。已知在渐进无限块长机制下，当在MAC上传输独立信源时，香农分离定理成立。然而，我们关注的是实际有限块长场景，此时分离的信源信道编码已知是次优的。我们提出了一种新颖的联合图像压缩与传输方案，设备以非正交方式发送其压缩图像表示。尽管非正交多址接入（NOMA）已知能实现容量区域，但据我们所知，针对实际系统的非正交联合信源信道编码（JSCC）方案此前尚未被研究。通过大量实验，我们证明了在重建图像质量方面，相较于采用现有DeepJSCC方法的正交传输方案，本方案在低带宽比场景下具有显著优势。我们公开共享源代码以促进进一步研究和可复现性。