News and Announcements

  • Low-Complex Synchronization Method for Intra-Body Links in the Terahertz Band

    April 16, 2024

    The recent literature focuses on deriving analytic channel models for intra-body links through the human tissues, including the analysis of achievable communication capacities in the terahertz band. A yet missing component, however, is a synchronization module to implement communication schemes in the intra-body link. Such synchronization module will ultimately bound the communication performance regarding the perceived signal to noise ratio (SNR) and bit error rate (BER), for instance. This paper contributes to the state of the art in two directions: (a) evaluating the bounds on the communication performance with the Cramer-Rao lower bound (CRLB) for the synchronization symbol timing offset (STO) and (b) designing a low-complex mechanism to synchronize communication.
  • Electric Circuit Representation of the Human Circulatory System to Estimate the Position of Nanosensors in Vessels

    March 26, 2024

    Nanodevices are the focus of research enhancing the detection and treatment of diseases in the human body. Focusing on the scenario where nanosensors are flowing with the blood in the human circulatory system (HCS), in this work, we investigate a model to predict their distribution along the various vessel segments. Although various approaches report solutions for localizing nanosensors in the body, it is also relevant to derive their stationary distribution along the vessel segments as a prior step to assess their actuation and sensing capabilities in the body. We use a Markov chain formulation to derive the stationary distribution of nanosensors. We evaluate the transition probabilities relying on the representation of vessels with electric circuit components. We implement the electric circuit representation of the left ventricle in the heart and the arteries to find the blood flow at vessel bifurcations and then compute the Markov chain probabilities. Our system also allows to reveal the dynamics of the movement of nanosensors during human activity. We illustrate results in two regimes as low and high activity to mimic the case when being at rest or doing sports.
    • Jorge Torres Gómez, Jorge Luis González Rios and Falko Dressler, "Electric Circuit Representation of the Human Circulatory System to Estimate the Position of Nanosensors in Vessels," Elsevier Nano Communication Networks, vol. 40, pp. 100499, July 2024. [DOI, BibTeX, PDF, More details]
  • Side Effects of IRS: On the Need for Coordination in 6G Multi-Operator IRS-assisted Networks

    February 15, 2024

    An IRS manipulates the channel propagation characteristics not only of signals of the operator who controls the IRS, but also of signals of other operators, although they operate at different frequencies. This is because IRS usually do not employ band pass filtering and, thus, also reflect signals of other frequencies. In this paper, we first introduce and discuss the problem of multi-operator coexistence issues that arise in IRS-assisted networks. We then propose splitting a single common IRS into multiple sub-blocks (subIRS) and controlling their dynamic assignment to operators, by taking into account the impact on the proximate operators as well. We show that the performance of the overall multi-operator network can be improved significantly if subIRS are properly assigned to the operators, compared to a purely static or random assignments. Our simulations results reveal that a significant improvement in terms of the sum rate and the fairness with respect to the respective data rate of the operators can be achieved.
    • Joana Angjo, Anatolij Zubow and Falko Dressler, "Side Effects of IRS: On the Need for Coordination in 6G Multi-Operator IRS-assisted Networks," Proceedings of IEEE Global Communications Conference (GLOBECOM 2023), 4th Workshop on Emerging Topics in 6G Communications (6GComm), Kuala Lumpur, Malaysia, December 2023, pp. 1380–1385. [DOI, BibTeX, PDF, More details]
  • Distributed UWB-based Ranging for Particle Tracking in Avalanches

    January 30, 2024

    The inner dynamics and transport mechanisms of avalanches - especially on a particle level - remain hidden for most observation approaches. In this paper, we present a particle based, distributed tracking system that is based on ultra-wideband (UWB) ranging and localization. UWB-based positioning is particularly challenging in outdoor scenarios covering large distances in complex topography and fast moving, mobile systems. Our system model considers multiple anchor nodes distributed with inter-node distances in the order of a few hundred meters. Mobile nodes, which move with the avalanche in the field, are tracked via UWB measurements. We present our prototype and demonstrate through first experiments the general feasibility of UWB-based tracking in snow environments.
    • Jonas Kuß, Anselm Köhler, Michael Neuhauser, Rene Neurauter, Johannes Gerstmayr, Jan-Thomas Fischer and Falko Dressler, "Distributed UWB-based Ranging for Particle Tracking in Avalanches," Proceedings of 19th IEEE/IFIP Conference on Wireless On demand Network Systems and Services (WONS 2024), Chamonix, France, January 2024, pp. 125–132. [DOI, BibTeX, PDF, More details]
  • Empowering the 6G Cellular Architecture with Open RAN

    December 01, 2023

    In this paper, we highlight the transformative potential of embracing novel cellular architectures by transitioning from conventional systems to the progressive principles of Open RAN. This promises to make 6G networks more agile, cost-effective, energy-efficient, and resilient. It opens up a plethora of novel use cases, ranging from ubiquitous support for autonomous devices to cost-effective expansions in regions previously underserved. The principles of Open RAN encompass: (i) a disaggregated architecture with modular and standardized interfaces; (ii) cloudification, programmability and orchestration; and (iii) AI-enabled data-centric closed-loop control and automation. We first discuss the transformative role Open RAN principles have played in the 5G era. Then, we adopt a system-level approach and describe how these Open RAN principles will support 6G RAN and architecture innovation. We qualitatively discuss potential performance gains that Open RAN principles yield for specific 6G use cases. For each principle, we outline the steps that research, development and standardization communities ought to take to make Open RAN principles central to next-generation cellular network designs.
    • Michele Polese, Mischa Dohler, Falko Dressler, Melike Erol-Kantarci, Rittwik Jana, Raymond Knopp and Tommaso Melodia, "Empowering the 6G Cellular Architecture with Open RAN," IEEE Journal on Selected Areas in Communications, vol. 42 (2), pp. 245–262, February 2024. [DOI, BibTeX, PDF, More details]
  • Explainability of Neural Networks for Symbol Detection in Molecular Communication Channels

    November 05, 2023

    Recent research in molecular communication (MC) suggests machine learning (ML) models for symbol detection, avoiding the unfeasibility of end-to-end channel models. However, ML models are applied as black boxes, lacking proof of correctness of the underlying neural networks (NNs) to detect incoming symbols. This paper studies approaches to the explainability of NNs for symbol detection in MC channels. Based on MC channel models and real testbed measurements, we generate synthesized data and train a neural network (NN) model for the detection of binary transmissions in MC channels. Using the local interpretable model-agnostic explanation (LIME) method and the individual conditional expectation (ICE), the findings in this paper demonstrate the analogy between the trained NN and the standard peak and slope detectors.
    • Jorge Torres Gómez, Pit Hofmann, Frank H. P. Fitzek and Falko Dressler, "Explainability of Neural Networks for Symbol Detection in Molecular Communication Channels," IEEE Transactions on Molecular, Biological and Multi-Scale Communications, vol. 9 (3), pp. 323–328, September 2023. [DOI, BibTeX, PDF, More details]
  • Towards the Simulation of WiFi Fine Time Measurements in NS3 Network Simulator

    October 19, 2023

    We present FTM-ns3, a software module which implements the 802.11 FTM protocol so that it can be used within the widely used ns3 network simulator. Moreover, we conducted experiments using commodity WiFi-FTM hardware, Intel 8260 and ESP32, and derived empirical error models which can be used in simulations to study the performance of novel FTM-based localization schemes under real channel propagation conditions while taking into account the specifics of the used WiFi hardware and configuration of FTM. Finally, we present results from simulations of a simple localization scheme based on FTM and multilateration which show the great influence of ranging inaccuracy introduced due to multipath propagation in typical indoor environments with line-of-sight (LoS) but strong multipath. Our module is provided to the community as open source and can be easily customized and extended.
  • Focusing on Information Context for ITS using a Spatial Age of Information Model

    September 26, 2023

    In order to cope with the vehicles’ mobility, such information is required to be as fresh as possible for proper operation of cooperative driving applications. The age of information (AoI) has been proposed as a metric for evaluating freshness of information; recently also within the context of intelligent transportation systems (ITS). We investigate mechanisms to reduce the AoI of data transported in form of beacon messages while controlling their emission rate. We aim to balance packet collision probability and beacon frequency using the average peak age of information (PAoI) as a metric. We propose a new way of interpreting the AoI by considering information context, thereby incorporating vehicles’ locations. As an example, we characterize such importance using the orientation and the distance of the involved vehicles.
  • TCOA: Triple-Check Offloading Algorithm for Roadside Units and Vehicular Microclouds in 5G Networks and Beyond

    August 26, 2023

    Next-generation intelligent transportation systems aim to achieve many cooperative perception and cooperative driving functions requiring considerable computational resources. Offloading such tasks via mobile edge computing is considered part of the solution and is currently being investigated in the scope of 5G networks and beyond. In this study, we propose an offloading system architecture to enable such offloading in a vehicular microcloud interconnected by a 5G core network. We model the system as a queueing model to derive closed-form solutions for selected performance metrics. Based on these insights, we propose the triple-check offloading algorithm (TCOA) to obtain both the best offloading ratio to the vehicular microcloud and the optimal maximum of the remaining vehicle instances in the vehicular microcloud. Our simulation results show that the proposed TCOA has better system performance than four other offloading schemes in terms of cost, response time, service rate, and cost response-time production service rate division (CRPSD).
    • Bo-Jun Qiu, Cheng-Ying Hsieh, Jyh-Cheng Chen and Falko Dressler, "TCOA: Triple-Check Offloading Algorithm for Roadside Units and Vehicular Microclouds in 5G Networks and Beyond," IEEE Access, vol. 11, pp. 84985–85001, August 2023. [DOI, BibTeX, PDF, More details]
  • Optimizing Terahertz Communication Between Nanosensors in the Human Cardiovascular System and External Gateways

    July 21, 2023

    This paper studies the intra-body communication channel between nanosensors flowing in the bloodstream and gateways attached to the skin using the terahertz (THz) spectrum. The channel model considers three layers through which the waveform travels: skin, tissue, and blood. To optimize the communication performance, this work investigates the impact of noise and mobility, and subsequently derives the trade-off between them. We illustrate the achievable bit error rate (BER) for THz intra-body channels considering communication through human tissue layers, including noise and random mobility of nanosensors in the blood system.
    • Jorge Torres Gómez, Jennifer Simonjan, Josep Miquel Jornet and Falko Dressler, "Optimizing Terahertz Communication Between Nanosensors in the Human Cardiovascular System and External Gateways," IEEE Communications Letters, vol. 27 (9), pp. 2318–2322, September 2023. [DOI, BibTeX, PDF, More details]
  • Centralized Model-Predictive Control with Human-Driver Interaction for Platooning

    June 11, 2023

    Cooperative adaptive cruise control presents an opportunity to improve road transportation through increase in road capacity and reduction in energy use and accidents. In this paper, we propose a centralized model predictive controller for a heterogeneous platoon of vehicles to reach a desired platoon velocity and individual inter-vehicle distances with driver-selected headway time. As a novel concept, we allow for interruption from a human driver in the platoon that temporarily takes control of their vehicle with the assumption that the driver will, at minimum, obey legal velocity limits and the physical performance constraints of their vehicle. The finite horizon cost function of our proposed platoon controller is inspired from the infinite horizon design. To the best of our knowledge, this is the first platoon controller that integrates human-driven vehicles. We illustrate the performance of our proposed design with a numerical study, demonstrating that the safety distance, velocity, and actuation constraints are obeyed.
    • Justin M. Kennedy, Julian Heinovski, Daniel E. Quevedo and Falko Dressler, "Centralized Model-Predictive Control with Human-Driver Interaction for Platooning," IEEE Transactions on Vehicular Technology, vol. 72 (10), pp. 12664–12680, October 2023. [DOI, BibTeX, PDF, More details]
  • Age of Information-based Performance of Ultrasonic Communication Channels for Nanosensor-to-Gateway Communication

    May 09, 2023

    We investigate the timely detection of abnormalities using nanosensors flowing in the blood vessels and reporting to external wearable devices. We develop analytic solutions to evaluate the information freshness using the average peak age of information (PAoI) metric. We model the mobility of nanosensors in the blood flow as a random process through a Markov chain. The communication capabilities with external devices to report detected abnormalities are modeled as a linear time-variant (LTV) channel. Besides, for communication with external devices, we study the impact of the mobility of nanosensors when using ultrasonic waveforms and integrate it with the PAoI formulation. As primary metrics, we use the bit error rate (BER), the packet error rate (PER), and the average PAoI. The results give clear insights into the impact of the position of the external monitor. We also illustrate that local communication performance almost does not influence the average PAoI.

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