Adapting CSI-Guided Imaging Across Diverse Environments: An Experimental Study Leveraging Continuous Learning

This study explores the feasibility of adapting CSI-guided imaging across varied environments. Focusing on continuous model learning through continuous updates, we investigate CSI-Imager's adaptability in dynamically changing settings, specifically transitioning from an office to an industrial environment. Unlike traditional approaches that may require retraining for new environments, our experimental study aims to validate the potential of CSI-guided imaging to maintain accurate imaging performance through Continuous Learning (CL). By conducting experiments across different scenarios and settings, this work contributes to understanding the limitations and capabilities of existing CSI-guided imaging systems in adapting to new environmental contexts.

$Λ$-Split: A Privacy-Preserving Split Computing Framework for Cloud-Powered Generative AI

In the wake of the burgeoning expansion of generative artificial intelligence (AI) services, the computational demands inherent to these technologies frequently necessitate cloud-powered computational offloading, particularly for resource-constrained mobile devices. These services commonly employ prompts to steer the generative process, and both the prompts and the resultant content, such as text and images, may harbor privacy-sensitive or confidential information, thereby elevating security and privacy risks. To mitigate these concerns, we introduce $\Lambda$-Split, a split computing framework to facilitate computational offloading while simultaneously fortifying data privacy against risks such as eavesdropping and unauthorized access. In $\Lambda$-Split, a generative model, usually a deep neural network (DNN), is partitioned into three sub-models and distributed across the user's local device and a cloud server: the input-side and output-side sub-models are allocated to the local, while the intermediate, computationally-intensive sub-model resides on the cloud server. This architecture ensures that only the hidden layer outputs are transmitted, thereby preventing the external transmission of privacy-sensitive raw input and output data. Given the black-box nature of DNNs, estimating the original input or output from intercepted hidden layer outputs poses a significant challenge for malicious eavesdroppers. Moreover, $\Lambda$-Split is orthogonal to traditional encryption-based security mechanisms, offering enhanced security when deployed in conjunction. We empirically validate the efficacy of the $\Lambda$-Split framework using Llama 2 and Stable Diffusion XL, representative large language and diffusion models developed by Meta and Stability AI, respectively. Our $\Lambda$-Split implementation is publicly accessible at https://github.com/nishio-laboratory/lambda_split.

Trans-Inpainter: A Transformer Model for High Accuracy Image Inpainting from Channel State Information

Radio Frequency (RF) signal-based multimodal image inpainting has recently emerged as a promising paradigm to enhance the capability of distortion-free image restoration by integrating wireless and visual information from the identical physical environment and has potential applications in fields like security and surveillance systems. In this paper, we aim to implement an RF-based image inpainting system that enables image restoration in a complex environment while maintaining high robustness and accuracy. This requires accurately converting RF signals into meaningful visual information and overcoming the challenges of RF signals in complex environments, such as multipath interference, signal attenuation, and noise. To tackle this problem, we propose Trans-Inpainter, a novel image inpainting method that utilizes the Channel State Information (CSI) of WiFi signals in combination with transformer networks to generate high-quality reconstructed images. This approach is the first to use CSI for image inpainting, which allows for extracting visual information from WiFi signals to fill in missing regions in images. To further improve Trans-Inpainter's performance, we investigate the impact of variations in CSI data on RF-based imaging ability, i.e., analyzing how the location of the CSI sensors, the combination of CSI from different sensors, and changes in temporal or frequency dimensions of CSI matrix affect the imaging quality. We compare the performance of Trans-Inpainter with RF-Inpainter, the state-of-the-art technology for RF-based multimodal image inpainting, under more realistic experimental scenarios, and with single-modality image inpainting models when only RF or image data is available, respectively. The results show that Trans-Inpainter outperforms other baseline methods in all cases.

Point Cloud-based Proactive Link Quality Prediction for Millimeter-wave Communications

This study demonstrates the feasibility of point cloud-based proactive link quality prediction for millimeter-wave (mmWave) communications. Image-based methods to quantitatively and deterministically predict future received signal strength using machine learning from time series of depth images to mitigate the human body line-of-sight (LOS) path blockage in mmWave communications have been proposed. However, image-based methods have been limited in applicable environments because camera images may contain private information. Thus, this study demonstrates the feasibility of using point clouds obtained from light detection and ranging (LiDAR) for the mmWave link quality prediction. Point clouds represent three-dimensional (3D) spaces as a set of points and are sparser and less likely to contain sensitive information than camera images. Additionally, point clouds provide 3D position and motion information, which is necessary for understanding the radio propagation environment involving pedestrians. This study designs the mmWave link quality prediction method and conducts two experimental evaluations using different types of point clouds obtained from LiDAR and depth cameras, as well as different numerical indicators of link quality, received signal strength and throughput. Based on these experiments, our proposed method can predict future large attenuation of mmWave link quality due to LOS blockage by human bodies, therefore our point cloud-based method can be an alternative to image-based methods.