Selected Publications

All Publications

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Data-driven Wireless Positioning

Maximilian Stahlke, Tobias Feigl, Sebastian Kram, Jonathan Ott, Jochen Seitz, Christopher Mutschler
Unlocking Artificial Intelligence: From Theory to Applications, Springer Nature 2024

Estimating Multipath Component Delays with Transformer Models

Jonathan Ott, Maximilian Stahlke, Tobias Feigl, Christopher Mutschler
IEEE Journal of Indoor and Seamless Positioning and Navigation (J-ISPIN) 2024

We implicitly estimate the number of MPCs and achieve subsample accuracy without using computationally intensive super-resolution techniques. Our approach outperforms known methods in detection performance and accuracy at different bandwidths. Our ablation study shows exceptional results on simulated and real datasets and generalizes to unknown radio environments.

Few-shot learning with uncertainty-based quadruplet selection for interference classification in GNSS data

Felix Ott, Lucas Heublein, Nisha Lakshmana Raichur, Tobias Feigl, Jonathan Hansen, Alexander Rügamer, Christopher Mutschler
2024 International Conference on Localization and GNSS (ICL-GNSS) 2024

We propose a few-shot learning (FSL) approach to adapt to new interference classes. Our method employs quadruplet selection for the model to learn representations using various positive and negative interference classes. Furthermore, our quadruplet vari-ant selects pairs based on the aleatoric and epistemic uncertainty to differentiate between similar classes. We recorded a dataset at a motorway with eight interference classes on which our FSL method with quadruplet loss outperforms other FSL techniques in jammer classification accuracy with 97.66%. https://gitlab.cc-asp.fraunhofer.de/darcy_gnsslFIOT_highway.

Fused-Layer CNNs for Memory-Efficient Inference on Microcontrollers

Mark Deutel, Frank Hannig, Christopher Mutschler, Jürgen Teich
Workshop on Machine Learning and Compression @NeurIPS 2024 2024

Fusing Structure from Motion and Simulation-augmented Pose Regression from Optical Flow for Challenging Indoor Environments

Felix Ott, Lucas Heublein, David Rügamer, Bernd Bischl, Christopher Mutschler
Journal of Visual Communication and Image Representation 2024

We enhance the performance of SfM and PoseNet in retrieving absolute poses, evaluate PGO to optimize the absolute pose and conduct a benchmark of 25 convolutional, recurrent, and Transformer networks in absolute and relative pose fusion.

Guided-SPSA: Simultaneous Perturbation Stochastic Approximation assisted by the Parameter Shift Rule

Maniraman Periyasamy, Axel Plinge, Christopher Mutschler, Daniel D Scherer, Wolfgang Mauerer
2024 IEEE International Conference on Quantum Computing and Engineering (QCE) 2024

We introduce a novel gradient estimation approach called Guided-SPSA, which meaningfully combines the parameter-shift rule and SPSA-based gradient approximation. We demonstrate numerically the performance of Guided-SPSA on different paradigms of quantum machine learning, such as regression, classification, and reinforcement learning.

Improving quantum and classical decomposition methods for vehicle routing

Laura S Herzog, Friedrich Wagner, Christian Ufrecht, Lilly Palackal, Axel Plinge, Christopher Mutschler, Daniel D Scherer
arXiv 2024

We demonstrate the utility of our novel shrinking method by successfully applying it to the archetypical traveling salesperson problem (TSP) which often occurs as a sub-problem in practically relevant vehicle routing applications. For a TSP with seven cities, we are able to retrieve an optimum solution by consecutively running two 7-qubit QAOA circuits. Without decomposition methods, we would require five times as many qubits. Our results offer insights into the performance of algorithms for combinatorial optimization problems within the constraints of current quantum technology.

Learning from Experience

Christopher Mutschler, Georgios Kontes, Sebastian Rietsch
Unlocking Artificial Intelligence: From Theory to Applications, Springer Nature 2024

Non-Line-of-Sight Detection for Radio Localization using Deep State Space Models

Leon Brasseler, Maximilian Stahlke, Thomas Altstidl, Tobias Feigl, Christopher Mutschler
14th International Conference on Indoor Positioning and Indoor Navigation (IPIN) 2024

Offsite evaluation of localization systems: criteria, systems and results from IPIN 2021-22 competitions

Francesco Potortì, Antonino Crivello, Soyeon Lee, Blagovest Vladimirov, Sangjoon Park, Yushi Chen, Long Wang, Runze Chen, Fang Zhao, Yue Zhuge, Haiyong Luo, Antoni Perez-Navarro, Antonio R Jiménez, Han Wang, Hengyi Liang, Cedric De Cock, David Plets....
IEEE Journal of Indoor and Seamless Positioning and Navigation (J-ISPIN) 2024

The main contribution of this work is to show a compilation of possible indoor positioning scenarios and different indoor positioning solutions to the same problem.

On-Device Training of Fully Quantized Deep Neural Networks on Cortex-M Microcontrollers

Mark Deutel, Frank Hannig, Christopher Mutschler, Jürgen Teich
IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems (TCAD) 2024

We present a method that enables efficient training of DNNs completely in place on the MCU using fully quantized training (FQT) and dynamic partial gradient updates. We demonstrate the feasibility of our approach on multiple vision and time-series datasets and provide insights into the tradeoff between training accuracy, memory overhead, energy, and latency on real hardware. The results show that compared to related work, our approach requires 34.8% less memory and has a 49.0% lower latency per training sample, with dynamic partial gradient updates allowing a speedup of up to 8.7 compared to fully updating all weights.

Optimal Joint Cutting of Two-qubit Rotation Gates

Christian Ufrecht, Laura S Herzog, Daniel D Scherer, Maniraman Periyasamy, Sebastian Rietsch, Axel Plinge, Christopher Mutschler
Physical Review A 2024

Circuit cutting, the partitioning of quantum circuits into smaller independent fragments, has become a promising avenue for scaling up current quantum-computing experiments. Here, we introduce a scheme for joint cutting of two-qubit rotation gates based on a virtual gate-teleportation protocol. With that, we significantly lower the previous upper bounds on the sampling overhead and prove the optimality of the scheme. Furthermore, we show that no classical communication between the circuit partitions is required. For parallel two-qubit rotation gates we derive an optimal ancilla-free decomposition, which includes cnot gates as a special case.

Qiskit-torch-module: Fast prototyping of quantum neural networks

Nico Meyer, Christian Ufrecht, Maniraman Periyasamy, Axel Plinge, Christopher Mutschler, Daniel D Scherer, Andreas Maier
2024 IEEE International Conference on Quantum Computing and Engineering (QCE) 2024

We develop the qiskit-torch-module, building on the widely used Qiskit software environment. It improves runtime performance by two orders of magnitude over comparable libraries, while facilitating low-overhead integration with existing code-bases. Moreover, the framework provides advanced tools for integrating quantum neural networks with PyTorch. The pipeline is tailored for single-machine compute systems, which constitute a widely employed setup in day-to-day research efforts.

Radio Foundation Models: Pre-training Transformers for 5G-based Indoor Localization

Jonathan Ott, Jonas Pirkl, Maximilian Stahlke, Tobias Feigl, Christopher Mutschler
14th International Conference on Indoor Positioning and Indoor Navigation (IPIN) 2024

We propose a self-supervised learning framework that pre-trains a general transformer (TF) neural network on 5G channel measurements that we collect on-the-fly without expensive equipment. Our novel pretext task randomly masks and drops input information to learn to reconstruct it. So, it implicitly learns the spatiotemporal patterns and information of the propagation environment that enable FP-based localization. Most interestingly, when we optimize this pre-trained model for localization in a given environment, it achieves the accuracy of state-of-the-art methods but requires ten times less reference data and significantly reduces the time from training to operation.

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