Recent publications

July 2024

First Polymer-based Passive Optical Waveguide for the Visible Range from 633 nm down to 488 nm

Tianwen Qian, Martin Schell, Moritz Kleinert, Crispin Zawadzki, David de Felipe Mesquida, Norbert Keil, Madeleine Weigel, Jakob Reck, Klara Mihov, Martin Kresse, Philipp Winklhofer, Csongor Keuer, Robin Kraft, Thomas Wiglanda, Arne Schleunitz

We investigated the transmission properties of optical waveguide based on fluorinated acrylate polymer and Ormocer® based polymer in the visible range (VIS). Laser transmission-induced transparency (LTIT) and fluorescence were observed in the...


July 2024

Model guidance via explanations turns image classifiers into segmentation models

Xiaoyan Yu, Wojciech Samek, Marina M.-C. Höhne, Dagmar Kainmüller, Jannik Franzen

Heatmaps generated on inputs of image classification networks via explainable AI methods have been observed to resemble segmentations of input images in many cases. We apply the "Right for the Right Reason" paradigm of imposing additional losses...


July 2024

PURE: Turning Polysemantic Neurons Into Pure Features by Identifying Relevant Circuits

Maximilian Dreyer, Wojciech Samek, Sebastian Lapuschkin, Johanna Vielhaben, Erblina Purelku

Neurons in deep neural networks can act polysemantically, meaning that they encode for multiple (unrelated) features. As such, understanding the inner workings of machine learning models becomes more difficult. We present PURE to turn...


July 2024

Explainable Concept Mappings of MRI: Revealing the Mechanisms Underlying Deep Learning-Based Brain Disease Classification

Christian Tinauer, Wojciech Samek, Sebastian Lapuschkin, Maximilian Dreyer, Reduan Achtibat, Frederik Pahde, Anna Damulina, Maximilian Sackl, Martin Soellradl, Reinhold Schmidt, Stefan Ropele, Christian Langkammer

While recent studies show high accuracy in the classification of Alzheimer's disease using deep neural networks, the underlying learned concepts have not been investigated. We separated Alzheimer's patients (n=117) from normal controls (n=219) by...


July 2024

Reactive Model Correction: Mitigating Harm to Task-Relevant Features via Conditional Bias Suppression

Dilyara Bareeva, Wojciech Samek, Sebastian Lapuschkin, Maximilian Dreyer, Frederik Pahde

DNNs are prone to relying on spurious correlations in data, posing risks in critical applications. Post-hoc methods exist to mitigate this without retraining but can globally shift latent features distributions, harming model performance. We...


July 2024

AttnLRP: Attention-Aware Layer-wise Relevance Propagation for Transformers

Reduan Achtibat, Thomas Wiegand, Wojciech Samek, Sebastian Lapuschkin, Maximilian Dreyer, Sayed M. V. Hatefi, Aakriti Jain

Our new method, AttnLRP, is the first to faithfully and holistically attribute not only input but also latent representations of transformer models with the computational efficiency similar to a single backward pass. We demonstrate that our...


July 2024

Understanding the (Extra-)Ordinary: Validating Deep Model Decisions with Prototypical Concept-based Explanations

Maximilian Dreyer, Wojciech Samek, Sebastian Lapuschkin, Reduan Achtibat

With PCX, we introduce a method that summarizes similar single explanations via prototypical ones. As such, we can understand the whole model behavior quickly and in detail. PCX further allows to validate individual predictions by communicating...


July 2024

Neuromorphic Wireless Device-Edge Co-Inference via the Directed Information Bottleneck

Yuzhen Ke, Slawomir Stanczak, Johannes Dommel, Zoran Utkovski, Osvaldo Simeone, Mehdi Heshmati

We consider neuromorphic wireless device-edge co-inference for edge intelligence applications. The directed information bottleneck principle is applied to extract the most relevant information for the task. The model demonstrates superior...


June 2024

Unlocking the Potential of Local CSI in Cell-Free Networks with Channel Aging and Fronthaul Delays

Lorenzo Miretti, Slawomir Stanczak

Centralized or distributed precoding? This is perhaps the most heated debate in the Cell-free Massive MIMO literature. However, in this work we argue that the best option may actually be a mix of the two. The reason is that centralized precoding,...


June 2024

Si3N4 Microring-Resonator-Based Integrated Photonic Sensor for Enhanced Label-Free Biofluid Analysis in the 850 nm Optical Band

Jakob Reck, Martin Schell, Moritz Kleinert, Crispin Zawadzki, David de Felipe Mesquida, Martin Kresse, Norbert Keil, Tianwen Qian, Madeleine Weigel, Klara Mihov, Philipp Winklhofer, Csongor Keuer

We present an innovative integrated photonic sensor for point-of-care applications using silicon nitride (Si3N4) tailored for biofluids analysis in the 850nm optical band. With microring resonators (MRR) we detect smallest changes in the...


June 2024

Spot Size Converters for Enhanced Coupling Efficiency Between Single Mode Fibers and High-Confinement Si3N4 Waveguides

Klara Mihov, Norbert Keil, Martin Schell, Moritz Kleinert, Crispin Zawadzki, David de Felipe Mesquida, Martin Kresse, Tianwen Qian, Madeleine Weigel, Jakob Reck, Philipp Winklhofer, Csongor Keuer, Aaron Elias Lutz, Daniel Preuß

For highly loss-sensitive applications of photonic integrated circuits (PICs), efficient coupling of high-confinement silicon nitride (Si3N4) passive waveguides with active optoelectronic components and standard single mode fibers (SMF) is...


June 2024

Wavelength Tunable, Polymer-Based Arrayed Waveguide Gratings for Hybrid Integration

Martin Kresse, Norbert Keil, Martin Schell, Moritz Kleinert, Crispin Zawadzki, David de Felipe Mesquida, Tianwen Qian, Madeleine Weigel, Jakob Reck, Klara Mihov, Philipp Winklhofer

We present a hybrid integrated photonic circuit with tunable arrayed waveguide gratings (AWGs) as (DE-)MUX stages for optical modulators for use in parallel convolution processing. The simulated and fabricated AWGs have 16 outputs with 500 GHz...


June 2024

Gaussian Splatting Decoder for 3D-aware Generative Adversarial Networks

Florian Tim Barthel, Peter Eisert, Anna Hilsmann, Wieland Morgenstern, Arian Beckmann

We present a novel approach that combines the high rendering quality of NeRF-based 3D-aware GANs with the flexibility and computational advantages of 3DGS. By training a decoder that maps implicit NeRF representations to explicit 3D Gaussian...


June 2024

Explainable AI for Time Series via Virtual Inspection Layers

Johanna Vielhaben, Wojciech Samek, Grégoire Montavon, Sebastian Lapuschkin

For time series data, where the input itself is often not interpretable, dedicated XAI research is scarce. In this work, we put forward a virtual inspection layer for transforming the time series to an interpretable representation and allows to...


June 2024

Towards Bridging the Gap between Near and Far-Field Characterizations of the Wireless Channel

Navneet Agrawal, Slawomir Stanczak, Renato L. G. Cavalcante, Ehsan Tohidi

Exploring near-field propagation is vital for 6G technologies like intelligent reflecting surfaces (IRS). Unlike far-field models, near-field models offer accuracy critical for applications such as beamforming and multiple-access, enhancing...


June 2024

Optimized Detection with Analog Beamforming for Monostatic Integrated Sensing and Communication

Rodrigo Hernangómez, Slawomir Stanczak, Renato L. G. Cavalcante, Zoran Utkovski, Jochen Fink

This paper presents an optimization framework for analog beamforming in monostatic integrated sensing and communication (ISAC), which maximizes sensing detection under self-interference cancellation via superiorized projections onto convex...


June 2024

An integrated 800 Gb/s O-band WDM optical transceiver enabled by hybrid InP-Polymer photonic integration

Efstathios Andrianopoulos, Christos Kouloumentas, Patrick Runge, Norbert Keil, Martin Moehrle, Annachiara Pagano, David de Felipe Mesquida, Michael Theurer, Martin Kresse, Hercules Avramopoulos, Anna Chiado Piat, Panos Groumas, Christos Tsokos, Paraskevas Bakopoulos, Madeleine Weigel, Maria Massaouti, Zerihun Tegegne, Giorgos Megas, Konstantina Kanta, Kostas Tokas

We propose and demonstrate a novel O-band wavelength division multiplexing (WDM) optical transceiver enabled by the hybrid photonic integration of Indium Phosphide (InP) components into a Polymer based photonic motherboard c! alled PolyBoard. The...


May 2024

Dynamic Exposure Visualization of Air Quality Data with Augmented Reality

Sylvain Renault, Oliver Schreer, Ingo Feldmann, Lieven Raes, Jurgen Silence

This paper introduces a new concept and outlines the implementation of an AR application designed for mobile devices. It can visualize real-time environmental data from various Open Data platforms. The scientific contribution lies in diverse...


May 2024

Time-bin entanglement at telecom wavelengths from a hybrid photonic integrated circuit

Hannah Thiel, Moritz Kleinert, Norbert Keil, Hauke Conradi, Lennart Jehle, Robert Chapman, Stefan Frick, Gregor Weihs, Holger Suchomel, Martin Kamp, Sven Hofling, Christian Schneider

We present a fiber-pigtailed hybrid photonic circuit comprising nonlinear waveguides for photon-pair generation and a polymer interposer reaching 68 dB of pump suppression and photon separation based on a polarizing beam splitter with > 25 dB...


April 2024

Towards an AI-enabled Connected Industry: AGV Communication and Sensor Measurement Datasets

Rodrigo Hernangómez, Slawomir Stanczak, Martin Kasparick, Gerhard Fettweis, Daniel Schäufele, Rafail Ismayilov, Oscar Dario Ramos-Cantor, Hugues Tchouankem, Philipp Geuer, Alexandros Palaois, Cara Watermann, Mohammad Parvini, Anton Krause, Thomas Neugebauer, Jose Leon Calvo, Bo Chen

We present iV2V and iV2i+, two machine-learning datasets for industrial wireless communication. The datasets cover sidelink and cellular communication involving autonomous robots together with localization and sensing data, which can be used to...


April 2024

Channel Charting for Beam Management in Sub-THz Systems

Patrick Agostini, Slawomir Stanczak, Zoran Utkovski

Sub-THz communication, vital for 6G, requires densification and multi-connectivity to overcome signal blockage. Efficient beam and user scheduling are crucial. We propose a low-complexity scheduling scheme using machine learning (ML), employing a...


April 2024

BiSPARCs for Unsourced Random Access in Massive MIMO

Patrick Agostini, Slawomir Stanczak, Zoran Utkovski

This paper addresses the massive MIMO unsourced random access problem in quasi-static Rayleigh fading. Our proposed coding scheme combines an outer LDPC code with an inner SPARC code, integrating channel estimation, single-user decoding, and...


April 2024

Animatable Virtual Humans: Learning pose-dependent human representations in UV space for interactive performance synthesis

Wieland Morgenstern, Peter Eisert, Anna Hilsmann, Milena Bagdasarian

We propose a novel representation of virtual humans for highly realistic real-time animation and rendering in 3D applications. We learn pose dependent appearance and geometry from highly accurate dynamic mesh sequences obtained from...


April 2024

Realness of face images can be decoded from non-linear modulation of EEG responses

Yonghao Chen, Peter Eisert, Anna Hilsmann, Sebastian Bosse, Arno Villringer, Vadim V. Nikulin, Milena Bagdasarian, Michael Gaebler, Tilman Stephani

We utilized an EEG dataset of steady-state visual evoked potentials in which participants were presented with human face images of different stylization levels. Assessing neuronal responses, we found a non-linear relationship between SSVEP...


April 2024

A protocol for annotation of total body photography for machine learning to analyze skin phenotype and lesion classification

Clare A Primiero, Frederik Pahde, Brigid Betz-Stablein, Nathan Ascott, Brian D'Alessandro, Seraphin Gaborit, Paul Fricker, Abigail Goldsteen, Sandra Gonzalez-Villa, Katie Lee, Sana Nazari, Hang Nguyen, Valsamis Ntsoukos, Balazs E. Pataki, Josep Quintana, Susana Puig, Gisele G. Rezze, Rafael Garcia, H. Peter Soyer, Josep Malvehy

AI has proven effective in classifying skin cancers using dermoscopy images. However, clinical application is limited when algorithms are not well-trained, or there is a lack of clinical context (e.g., medical history). The increasing use of...


April 2024

UL-DL Duality for Cell-Free Massive MIMO With Per-AP Power and Information Constraints

Lorenzo Miretti, Slawomir Stanczak, Renato L. G. Cavalcante, Emil Björnson

This article advances the theoretical foundations of user-centric cell-free massive MIMO networks. In particular, by means of a novel UL-DL duality principle for fading channels, it settles the optimality of the recently developed “team MMSE”...


April 2024

Signal separation in radio spectrum using self-attention mechanism

Fadli Damara, Slawomir Stanczak, Zoran Utkovski

Traditional signal processing methods often fall short compared to data-driven approaches in a signal separation problem that involves co-channel signals, where the energy content of the interference component overlaps with the transmitted signal...


March 2024

From Hope to Safety: Unlearning Biases of Deep Models via Gradient Penalization in Latent Space

Maximilian Dreyer, Wojciech Samek, Sebastian Lapuschkin, Christopher J. Anders, Frederik Pahde

We present a novel method ensuring the right reasons on the concept level by reducing the model's sensitivity towards biases through the gradient. When modeling biases via Concept Activation Vectors, we highlight the importance of choosing robust...


March 2024

Real-Time Algorithms for Combined eMBB and URLLC Scheduling

Tano Bischoff, Slawomir Stanczak, Martin Kasparick, Ehsan Tohidi

This paper investigates efficient scheduling algorithms for coexistence scenarios of devices with different quality of service requirements, such as URLLC and eMBB. It proposes a low-complexity algorithm that outperforms current methods, with...


March 2024

Predictive Handover Optimization

Vahid Rajabi, Slawomir Stanczak, Martin Kasparick, Jochen Fink

Future networks aim for higher data rates through cell densification, leading to frequent handovers and increased signaling overhead for moving user equipment (UE). This paper presents an optimization scheme using predicted channel state...



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