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1. Learning an Adaptive Forwarding Strategy for Mobile Wireless Networks: Resource Usage vs. Latency

   Manfredi, Victoria; Wolfe, Alicia P.; Zhang, Xiaolan; Wang, Bing (December 2022, Reinforcement Learning for Real Life (RL4RealLife) Workshop in the 36th Conference on Neural Information Processing Systems (NeurIPS))

   Mobile wireless networks present several challenges for any learning system, due to uncertain and variable device movement, a decentralized network architecture, and constraints on network resources. In this work, we use deep reinforcement learning (DRL) to learn a scalable and generalizable forwarding strategy for such networks. We make the following contributions: i) we use hierarchical RL to design DRL packet agents rather than device agents, to capture the packet forwarding decisions that are made over time and improve training efficiency; ii) we use relational features to ensure generalizability of the learned forwarding strategy to a wide range of network dynamics and enable offline training; and iii) we incorporate both forwarding goals and network resource considerations into packet decision-making by designing a weighted DRL reward function. Our results show that our DRL agent often achieves a similar delay per packet delivered as the optimal forwarding strategy and outperforms all other strategies including state-of-the-art strategies, even on scenarios on which the DRL agent was not trained. 

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2. Progress in developing a bark beetle identification tool

   https://doi.org/10.1371/journal.pone.0310716  

   Marais, G Christopher; Stratton, Isabelle C; Johnson, Andrew J; Hulcr, Jiri (June 2025, PLOS One)

   Kajtoch, Łukasz (Ed.)

   This study presents an initial model for bark beetle identification, serving as a foundational step toward developing a fully functional and practical identification tool. Bark beetles are known for extensive damage to forests globally, as well as for uniform and homoplastic morphology which poses identification challenges. Utilizing a MaxViT-based deep learning backbone which utilizes local and global attention to classify bark beetles down to the genus level from images containing multiple beetles. The methodology involves a process of image collection, preparation, and model training, leveraging pre-classified beetle species to ensure accuracy and reliability. The model's F1 score estimates of 0.99 and 1.0 indicates a strong ability to accurately classify genera in the collected data, including those previously unknown to the model. This makes it a valuable first step towards building a tool for applications in forest management and ecological research. While the current model distinguishes among 12 genera, further refinement and additional data will be necessary to achieve reliable species-level identification, which is particularly important for detecting new invasive species. Despite the controlled conditions of image collection and potential challenges in real-world application, this study provides the first model capable of identifying the bark beetle genera, and by far the largest training set of images for any comparable insect group. We also designed a function that reports if a species appears to be unknown. Further research is suggested to enhance the model's generalization capabilities and scalability, emphasizing the integration of advanced machine learning techniques for improved species classification and the detection of invasive or undescribed species. 

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3. MLP+NeuroSimV3.0: Improving On-chip Learning Performance with Device to Algorithm Optimizations

   Yandong Luo, Xiaochen Peng (July 2019, International Conference on Neuromorphic Systems (ICONS))

   On-chip learning with compute-in-memory (CIM) paradigm has become popular in machine learning hardware design in the recent years. However, it is hard to achieve high on-chip learning accuracy due to the high nonlinearity in the weight update curve of emerging nonvolatile memory (eNVM) based analog synapse devices. Although digital synapse devices offer good learning accuracy, the row-by-row partial sum accumulation leads to high latency. In this paper, the methods to solve the aforementioned issues are presented with a device-to-algorithm level optimization. For analog synapses, novel hybrid precision synapses with good linearity and more advanced training algorithms are introduced to increase the on-chip learning accuracy. The latency issue for digital synapses can be solved by using parallel partial sum read-out scheme. All these features are included into the recently released MLP + NeuroSimV3.0, which is an in-house developed device-to-system evaluation framework for neuro-inspired accelerators based on CIM paradigm. 

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4. Unsupervised Contrastive Learning for Robust RF Device Fingerprint Under Time-Domain Shift

   Chen, Jun; Wong, Weng-Keen; Hamdaoui, Bechir (June 2024, IEEE International Conference on Communications)

   Radio Frequency (RF) device fingerprinting has been recognized as a potential technology for enabling automated wireless device identification and classification. However, it faces a key challenge due to the domain shift that could arise from variations in the channel conditions and environmental settings, potentially degrading the accuracy of RF-based device classification when testing and training data is collected in different domains. This paper introduces a novel solution that leverages contrastive learning to mitigate this domain shift problem. Contrastive learning, a state-of-the-art self-supervised learning approach from deep learning, learns a distance metric such that positive pairs are closer (i.e. more similar) in the learned metric space than negative pairs. When applied to RF fingerprinting, our model treats RF signals from the same transmission as positive pairs and those from different transmissions as negative pairs. Through experiments on wireless and wired RF datasets collected over several days, we demonstrate that our contrastive learning approach captures domain-invariant features, diminishing the effects of domain-specific variations. Our results show large and consistent improvements in accuracy (10.8% to 27.8%) over baseline models, thus underscoring the effectiveness of contrastive learning in improving device classification under domain shift. 

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5. Leveraging MIMO Transmit Diversity for Channel-Agnostic Device Identification

   Nora Basha, Bechir Hamdaoui (January 2022, IEEE International Conference on Communications)

   The accurate identification of wireless devices is critical for enabling automated network access monitoring and authenticated data communication in large-scale networks; e.g., IoT networks. RF fingerprinting has emerged as a potential solution for device identification by leveraging the transmitter unique manufacturing impairments of the RF components. Although deep learning is proven efficient in classifying devices based on the hardware impairments, trained models perform poorly due to channel variations. That is, although training and testing neural networks using data generated during the same period achieve reliable classification, testing them on data generated at different times degrades the accuracy substantially. To the best of our knowledge, we are the first to propose to leverage MIMO capabilities to mitigate the channel effect and provide a channelresilient device classification. For the proposed technique we show that, for Rayleigh channels, blind partial channel estimation enabled by MIMO increases the testing accuracy by up to 40% when the models are trained and tested over the same channel, and by up to 60% when the models are tested on a channel that is different from that used for training. 

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