Aktuelle Publikationen

August 2024

Localization in Dynamic Indoor MIMO-OFDM Wireless Systems using Domain Adaptation

Rafail Ismayilov, Slawomir Stanczak, Renato L. G. Cavalcante

Predicting user locations in dynamic indoor wireless environments is improved by using domain adaptation techniques. This approach effectively addresses challenges such as the birth, death, and drift of scattering clusters caused by environmental...


August 2024

W-Band Beamforming Front-End Implementation and Outdoor Trials for Mobile Backhaul and Access

Mathis Schmieder, Wilhelm Keusgen, Michael Peter, Mehrnoosh Mazhar Sarmadi, Alper Schultze, Dirk Schwantuschke

This paper presents the design and implementation of a novel analog beam former for the frequency range around 85 GHz. The capabilites are demonstrated through an outdoor trial in an urban environment, showcasing the potential of high frequency...


August 2024

When Only Time Will Tell: Interpreting How Transformers Process Local Ambiguities Through the Lens of Restart-Incrementality

Brielen Madureira, Patrick Kahardipraja, David Schlangen

A method to interpret how restart-incremental bidirectional models process local ambiguities, with an analysis on meaning representation and dependency parsing.


August 2024

32 GBd, 109 Gbit/s probabilistically shaped THz wireless transmission using PIN-PD based photonic upconversion

In-Ho Baek, Martin Schell, Colja Schubert, Ronald Freund, Robert Elschner, Simon Nellen, Robert Kohlhaas, Oliver Stiewe, Garrit William Johannes Schwanke

We characterize the performance of high symbol rate probabilistic constellation shaping (PCS) in a THz wireless link utilizing a PIN photodiode-assisted transmitter. Using a 64-QAM base constellation we demonstrate high data rate adaptivity,...


August 2024

Gradual Change Detection in Covariance Matrix: A Lazy Approach

Sida Dai, Lars Thiele, Slawomir Stanczak, Setareh Maghsudi, Ehsan Tohidi

The covariance matrix offers a balance between frequent channel estimations and maintaining acceptable system performance. In this work, we propose an intelligent autonomous mechanism that monitors changes in the covariance matrix, minimizing...


August 2024

Sub-THz D-Band Integrated Analog Beamforming Front-End Prototyping and 6G Outdoor Trials

Ramez Askar, Thomas Haustein, Slawomir Stanczak, Wilhelm Keusgen, Michael Peter, Mathis Schmieder, Thomas Merkle, Jaehoon Chung, Sven Wittig, Laurenz John, Yonghak Suh, Jongpil Lee

This paper reports the development outcomes of the world’s first integrated analog beamforming – transmit and receive – wireless front-ends operating in the D-band (a sub- THz band), particularly designed to operate within 150 GHz to 170 GHz...


August 2024

Two-timescale weighted sum-rate maximization for large cellular and cell-free massive MIMO

Lorenzo Miretti, Slawomir Stanczak, Emil Björnson

Discover a groundbreaking two-timescale method for optimizing the weighted sum-rate in future multi-antenna wireless systems. Our innovative approach overcomes the severe scalability issues of traditional methods, namely the extreme computational...


August 2024

User-Centric Monostatic Sensing Aided by Reconfigurable Intelligent Surfaces

Abdolvakil Fazli, Slawomir Stanczak, Zoran Utkovski, Ehsan Tohidi

We propose that deploying Reflecting Intelligent Surfaces (RIS) as auxiliary sensors can either enable (in cases of blockage) or assist UEs in improving sensing performance. This can be achieved by deploying larger surfaces, offering superior...


August 2024

Load Balancing in O-RAN

Hammad Zafar, Slawomir Stanczak, Martin Kasparick, Ehsan Tohidi

Efficiently managing network load has long been a challenge in wireless networks, and open radio access networks (O-RAN) can offer a potential solution through open interfaces and optimization capabilities. This paper focuses on addressing the...


Juli 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...


Juli 2024

Distributed Convex Optimization “Over-the-Air” in Dynamic Environments

Navneet Agrawal, Slawomir Stanczak, Renato L. G. Cavalcante, Masahiro Yukawa

The paper proposes a class of distributed algorithms where the consensus step is implemented in a scalable and truly decentralized fashion using a novel communication protocol based on the “over-the-air” function computation (OTA-C)...


Juli 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...


Juli 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...


Juli 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...


Juli 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...


Juli 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...


Juli 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...


Juli 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...


Juni 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,...


Juni 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...


Juni 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...


Juni 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...


Juni 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...


Juni 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...


Juni 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...


Juni 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...


Juni 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...


Mai 2024

Reliability Assurance in RIS-Assisted 6G Campus Networks

Ehsan Tohidi, Slawomir Stanczak, Stefan Schmid, Admela Jukan, Max Franke, André Drummond, Cao Vien Phung, Naveed Khan

Campus networks have become a major market segment for cellular communication technology, providing a flexible communication infrastructure to meet the specific de-pendability and performance requirements of industry verticals. With the emerging...


Mai 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...


Mai 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...


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