We design for an IoT & 6G future.
And beyond. 🚀
Explore our expertise on low-power design, wireless power, wireless communication (5G and 6G), and localization.
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Energy-Saving Precoder Design for Narrowband and Wideband Massive MIMO
This study focuses on massive MIMO precoders optimizing power amplifiers and base station power consumption under rate requirements. The analytical and numerical characterization of the solutions reveal that (a) in systems with a small number of subcarriers, the activation of a specific set of antennas with non-uniform power allocation minimizes the power amplifiers consumption, and (b) in systems with a large number of subcarriers, the activation of a certain number of antennas with uniform power allocation minimizes the base station consumption. In general, antennas are progressively activated as a function of the load.
The Art of Designing Remote IoT Devices—Technologies and Strategies for a Long Battery Life
The art of designing remote IoT devices requires an application-oriented approach, where a meticulous design and smart operation are essential to grant a long battery life. In particular we demonstrate the importance of strategies such as "think before you talk" and "race to sleep". As maintenance of IoT nodes is often cumbersome due to being deployed at hard to reach places, extending the battery life of these devices is critical. Moreover, the environmental impact of batteries further demonstrates the need for a longer battery life in order to reduce the number of batteries used.
An Experimental Evaluation of Energy Trade-Offs in Narrowband IoT
In this paper, we compare a theoretical model found in literature with the results of this real-life setup. Our measurements indicate a less optimistic power profile than proposed in the theoretical model. We also highlight the contribution of each of the Narrowband IoT (NB-IoT) defined modem states to the typical energy profile of an NB-IoT node. This allows for a more realistic model for energy simulations and for further optimization of the power efficiency of NB-IoT applications.
An Energy-Efficient LoRa Multi-Hop Protocol through Preamble Sampling
In this work, we propose a multi-hop LoRa-based protocol tailored to battery-powered IoT devices. The protocol uses a combination of preamble sampling and dynamic payload aggregation to improve energy efficiency. In contrast to prior work, a fine-grained energy model of the devices is considered, impacting the design choices in all protocol layers, i.e., application, medium access control (MAC), and routing layer. The protocol is implemented in C and made public in open source. A first experiment indicates a high packet delivery ratio and showcases the dynamic aggregation feature.
Dramco Uno: Create your first IoT device
This tutorial covers the assembly and programming of a wireless IoT sensor for data collection over LoRaWAN. It's a valuable resource for both makers and researchers interested in exploring the capabilities of LoRaWAN technology.
Connecting Embedded Sensors in the IoT
In this hands-on session the attendees will experience the development of a wireless sensor node. More specifically, how low-power operation can be achieved by clever utilization of the available resources. Such design choices include: selecting the right wireless technology, duty-cycled operation, exploiting sleep capabilities, etc.
IoT: Sensors, Wireless Technologies and its Applications (University of Abomey Calavi, Benin)
5 researchers from the DRAMCO laboratory and 5 students from the Engineering and Sustainability course went to the University of Abomey-Calavi, Benin, to collaborate on the environmental and agriculture applications of Internet of Things (IoT). The program started with a 2-day hands-on tutorial on IoT, followed by a 3rd day with presentations, panel discussions, and a poster session by the students.
Wireless Power Transfer: Systems, Circuits, Standards, and Use Cases
This survey provides a comprehensive overview of the state of the art on different technological concepts, including electromagnetic coupled and uncoupled systems and acoustic technologies. Solutions to transfer mW to MW of power, over distances ranging from millimeters to kilometers, and exploiting wave concepts from kHz to THz, are covered. Of particular interest for designers is the discussion of implementation and operational aspects, standards, and safety relating to regulations. A high-level catalog of potential applications maps these to adequate technological options for wireless power transfer.
Impact of Array Configuration on Head-Mounted Display Performance at mm Wave Bands
This work presents indoor 28 GHz mmWave channel measurement data, collected during HMD mobility, and studies the dominant eigenmode (DE) gain. We propose 3 performance metrics - gain trade-off, gain volatility, and minimum service trade-off - for evaluating the performance of a multi-array HMD and apply the metrics to indoor 28 GHz channel measurement data. Evaluation results indicate, that 3 arrays provide stable temporal channel gain. Adding a 4th array further increases channel capacity, while any additional arrays do not significantly increase physical layer performance.
Measurement-Based Validation of Z3RO Precoder to Prevent Nonlinear Amplifier Distortion in Massive MIMO Systems
In multiple input multiple output (MIMO) systems, precoding allows the base station to spatially focus and multiplex signals towards each user. However, distortion introduced by power amplifier nonlinearities coherently combines in the same spatial directions when using a conventional precoder. This strongly limits the user performance and creates unauthorized out-of-band (OOB) emissions. In order to overcome this problem, the zero third-order distortion (Z3RO) precoder was recently introduced, which constrains the third-order distortion at the user to be zero. In this work, the performance of the Z3RO precoder is validated based on real-world channel measurement data.
Deep Unfolding for Fast Linear Massive MIMO Precoders under a PA Consumption Model
Massive multiple-input multiple-output (MIMO) precoders are typically designed by minimizing the transmit power subject to a quality-of-service (QoS) constraint. However, current sustainability goals incentivize more energy-efficient solutions and thus it is of paramount importance to minimize the consumed power directly. Minimizing the consumed power of the power amplifier (PA), gives rise to a convex, non-differentiable optimization problem, which can be solved using convex solvers. Additionally, this problem can be solved using a proximal gradient descent (PGD) algorithm, which suffers from slow convergence. In this work, in order to overcome the slow convergence, a deep unfolded version of the algorithm is proposed.
UAV-Based Servicing of IoT Nodes: Assessment of Ecological Impact
Internet of Things (IoT) nodes get deployed for a variety of applications and often need to operate on batteries. This restricts their autonomy and/or can have a major ecological impact. The core idea is to use a unmanned aerial vehicle (UAV) to provide energy to IoT nodes, and hence prolong their autonomy. In particular, the objective is to perform a comparison of the total energy consumption resulting from UAV-based recharging or battery replacement versus full provisioning at install time or remote RF-based wireless power transfer. The ecological aspects of the proposed methods are evaluated, e.g., considering toxic materials and e-waste.
Automated and Interference-Free Inventory Solution using Energy-Neutral BLE Tags
Maintaining an accurate and up-to-date database of the location of assets is a challenge, especially in complex logistic processes. In hospitals, intolerable time is lost searching for tools and expensive surgical equipment. We developed a reliable solution for tracking assets in hospitals, based on energy-neutral RF sensors using Bluetooth Low Energy (BLE) tags. By shielding the insides of closets, we preventing the signals to contaminate the RF-critical environments, nor generating or receiving interference from neighboring systems. Measurements show that the proposed solution can energize all spatially dispersed tags within this closet efficiently.
Multi-RAT for IoT: The Potential in Combining LoRaWAN and NB-IoT
The design of such multi-RAT solutions based on the diverse characteristics of the technologies offers interesting opportunities. We have assessed both the potential gains and the overhead brought by a multi-RAT solution. To that end, we have evaluated key IoT node requirements in function of payload size and link quality: energy efficiency, coverage, payload size, latency performance, QoS, and cost efficiency.
REINDEER: REsilient INteractive applications through hyper Diversity in Energy Efficient RadioWeaves technology
KU Leuven is proud to be part of the REINDEER project (reindeer-project.eu). In REINDEER we will develop, evaluate and validate the RadioWeaves concept. In RadioWeaves, objects and buildings will be equiped with a "fabric" of distributed antennas. This topology will power new resilient interactive applications and cell-free operation.
Massive MIMO for Machine Type Communication
5G terminals will need to support a diverse set of service requirements. Many devices will require Machine Type Communication (MTC). Both unlicensed bands below 1 GHz and the 3.5 GHz licensed bands are considered for these services. We try to experimentally assess the end-to-end service enhancement for MTC by Massive MIMO operation.
Low-cost synchronization for WLAN Sensors - IEEE Conference Publication
Sensing applications with many sensors often rely on synchronized measurements in order to operate correctly. We have developed an extension to RBIS that can be used over a large range, spanning multiple access points, and with a synchronization error that is substantially smaller than that of NTP, i.e., less than 1 ms.
Behandelen van NMSA via draadloze sensoren
In deze masterproef wordt een sensor node ontwikkeld voor het langdurig en nauwkeurig meten van bewegingen in het algemeen en met een specifieke focus op de positie van de onderrug. Het doel is om patiënten met verschillende sensor nodes te voorzien om zo een beeld te krijgen van de positie van de rug.
IoT with a Soft Touch (IWAST)
Wij maken een 'plug-and-play' IoT-rugzak, waarmee iedereen eenvoudig aan de slag kan om een IoT-toepassing te bouwen. De technische moeilijkheden hebben wij voor je weggenomen; zodat jij al je aandacht kan richten op het probleem dat je wil aanpakken met IoT.
Oases van rust: geluidsniveau meting in en rond de stad (IOASE)
In het City Of Things project “Oases van rust” werkt de onderzoeksgroep Dramco van KU Leuven Technologiecampus Gent samen met stad Dendermonde en gemeente Aalter om Internet-of-Things (IoT) sensoren te ontwikkelen die het geluidsniveau in de stad kunnen monitoren.
Cross-layer framework and optimization for efficient use of the energy budget of IoT Nodes
Both physical and MAC-layer need to be jointly optimized to maximize the autonomy of IoT devices. Therefore, a cross-layer design is imperative to effectively realize LPWANs. In the present paper, a cross-layer assessment framework including power modeling is proposed. Through this simulation framework, the energy consumption of IoT devices, currently deployed in LoRaWAN networks, is evaluated.
Internet of Trees (IoTree)
Via het Internet-of-Trees kan de gezondheid van bomen vanop afstand gemonitored worden. De bomen worden verbonden via het Internet door middel van de LoRa technologie.
De temperatuur van de schors en de buitenlucht wordt gemonitord om de gezondheid van de boom te schatten. Deze waarden worden doorgestuurd via LoRaWAN naar onze IoTree server.
A Deployable LPWAN Platform for Low-Cost and Energy-Constrained IoT Applications
The resulting platform allows entry-level prototyping, while featuring an ultra-low sleep power of 25.2 μW . This makes lpwan sensor applications accessible in domains that would otherwise require custom hardware development.
Long Range IoT Connections: Experimental Confirmation of the Energy Drain and Exploration of Escape Routes
This paper assesses the discrepancy of satisfying both low power and long range requirements. A versatile module has been developed to assess and optimize power modes in order to maximize the autonomy of IoT devices.
LoRa Physical Layer Evaluation for Point-to-Point Links and Coverage Measurements in Diverse Environments
This paper focuses on Point-to-Point LoRa connections. We report on coverage measurements performed in three distinct environments, i.e., coastal, forest and urban. Our field experiments demonstrate coverage up to 1 km with antennas at only 1.5 m height in an urban scenario. In free Line-of-Sight (LoS) this coverage is extended to 4 km. Based on these results, we are developing a path loss model in future work.
Glue-and-Play Sensing Solution for Remotely Monitoring Drinking Frequency of Horses
We present a set-and-forget sensing solution to remotely monitor the drinking frequency of horses. Our solution consists of an easy to deploy sensor and LPWAN connectivity. We conceived a flexible capacitive sensor that can simply be glued into the drinking bowl.
Slimme boeien voor de kust
In het labo Embedded Systemen 2 werken studenten uit de master industriële ingenieurswetenschappen een proof-of-concept uit binnen een hedendaagse problematiek. Zo raken boeien op zee wel eens op drift door stormweer. In samenwerking met VLOOT werd een draadloos (LoRa) connecteerde boei voor de kust van Oostende uitgezet.
LoRa Energy Calculator
By using the Dramco LoRa Energy Calculator, you can estimate the amount of energy your LoRa application will use. It takes various parameters into account, and estimates the life time based on the exact type of battery.
LPWAN Battery Autonomy Calculators
This tool utilizes a comprehensive energy profile analysis to calculate the autonomy of Sigfox and LoRaWAN nodes, taking into account various factors. By assessing power consumption patterns and environmental variables, it provides valuable insights into the expected operational lifespan of these IoT devices.
LoRa Network Simulator to Monitor Energy Consumption
In order to estimate the total energy consumed by using LoRaWAN, this simulator was developed. Parameters on the node (such as location and energy profile) are taken into account, as well as the simulated air interface.
Connecting embedded sensors in the Internet-of-Things
Embedded sensors are enabling numerous smart services in domains ranging from healthcare to smart homes and cities. They are waiting to be connected to the internet and rapidly becoming crucial components of a valuable Internet of Things (IoT).
Characterization of LoRa Point-to-Point Path Loss: Measurement Campaigns and Modeling Considering Censored Data
In this article, we evaluate the coverage and model the path loss (PL) of these links, based on experimental campaigns in three environments: 1) urban; 2) forest; and 3) coastal. Despite the unfavorable radio propagation in the urban scenario and the densely forested terrain, a maximum range of 1 km is achieved.
Improved Commissioning in Indoor Wireless Networks Through Sensor Fusion Using Clustering
Commissioning of wireless networks can be a burdensome and costly task when the number of nodes increases significantly. This paper presents a method to reduce the required effort and cost by automating parts of the commissioning process, based on the location of the wireless devices.
Bringing Energy to IoT Nodes: an Unmanned Vehicle for Wireless Power Transfer
As the number of sensors increases and they may get embedded in difficult to reach places, human intervention generates a high overhead. To alleviate this problem, an Unmanned Vehicle (UV)-based approach exploiting Wireless Power Transfer (WPT) was conceived.
Quilla outdoor ecolighting
Een Belgisch product dat in samenwerking met het labo voor lichttechnologie en Dramco van de KU Leuven werd ontwikkeld tot een innoverende en kwalitatief hoogstaande verlichting zonder netsvoorziening. De gebruiker kan een gewenst verlichtingsschema instellen op afstand via PC, smartphone of tablet.
Geconnecteerde schapen
Wist je dat schapen heel effectief zijn in het onderhoud en de bescherming van de vegetatie aan artificiële dijken? Helaas is de herder niet op ieder moment van de dag ter plaatse. Studenten uit de master industriële ingenieurswetenschappen connecteerden batterijgevoede sensoren aan schapen om inzicht te krijgen in hun gedrag!
Open Sensor en Gateway Technologie voor Rijkere IoT Omgevingen (SMIoT)
De fysieke wereld wordt via sensoren, actuatoren en netwerken verbonden met computersystemen. Voor vele sensoren zijn slechts laag niveau ontwikkelingskits beschikbaar. Bovendien worden sensoren dikwijls ontwikkeld met het oog op een specifieke toepassing. Het SMIoT project focust precies op het ontwikkelen van bruikbare richtlijnen en software ondersteuning die ingezet kunnen worden op sensor en gateway niveau.
Accurate and Low-Power Ultrasound–Radiofrequency (RF) Indoor Ranging Using MEMS Loudspeaker Arrays
Accurately positioning energy-constrained devices indoors is critical for many applications, and hybrid RF–acoustic ranging systems are a promising solution. Replacing single loudspeakers with a phased loudspeaker array enhances the signal-to-interference-plus-noise ratio, improving ranging accuracy. Simulations show that vertical phased-array configurations significantly reduce ranging errors compared to traditional single-loudspeaker systems.
An Acoustic Simulation Framework to Support Indoor Positioning and Data Driven Signal Processing Assessments
We present an indoor acoustic simulation framework for both ultrasonic and audible signaling, facilitating fast data generation and positioning development. The Pyroomacoustics-based model uses an image-source model and ray tracing to simulate acoustic signaling, supporting various speaker and microphone configurations. Simulations closely match real measurements, and the framework's modular design allows for customization; the code is open source.
Research Publications Localization Tools
Positioning Energy-Neutral Devices: Technological Status and Hybrid RF-Acoustic Experiments
The digital transformation is driving the adoption of Internet-of-Things technologies, raising questions about the positioning of these devices. Conventional RF-based techniques struggle with balancing accuracy and low power consumption, but hybrid RF-acoustic approaches offer a promising alternative by leveraging the slow propagation of sound for precise measurements and RF for synchronization and power. Experiments show that RF-harvested energy can achieve 10 cm accuracy, though challenges remain for accurate 3D positioning.
Anchor Layout Optimization for Ultrasonic Indoor Positioning Using Swarm Intelligence
Indoor positioning applications demand higher precision and accuracy, which can be significantly impacted by optimal anchor placement and multiple distributed anchor nodes. This paper uses an ultrasonic 3D positioning system and a geometric-based simulation framework, employing a particle swarm optimization (PSO) algorithm for 4 to 10 anchors, to investigate these factors. Results show that optimal placement is crucial for high precision and reliability, while adding more anchors provides supplementary improvements.
Position Dependent Anchor Selection for Scalable Hybrid RF-Acoustic Indoor Positioning
Accurate 3D indoor positioning is crucial for many applications. This study compares anchor selection methods in a hybrid RF-acoustic positioning system using two mechanisms: a classical least squares (LS) estimator and a circular convolutional neural network (CCNN) model. Results show that anchor selection improves accuracy, particularly in Non-Line-of-Sight (NLoS) conditions, with ML methods outperforming traditional algorithms and benefiting from using all available anchors.
Techtile: a Flexible Testbed for Distributed Acoustic Indoor Positioning and Sensing
The Techtile infrastructure offers a unique R&D facility with dispersed electronics for 3D signal transmission and capture, supporting smooth prototyping to commercial product development. Acoustic parameters, including reverberation and ambient noise, are measured to enhance the accuracy of acoustic indoor positioning and sensing systems. The room mimics home or quiet office environments acoustically, with a maximum RT60 of 1.17s at 5kHz, and many designs are available as open source.
Toward Energy-Efficient Massive MIMO: Graph Neural Network Precoding for Mitigating Non-Linear PA Distortion
Massive MIMO systems are typically designed assuming linear power amplifiers (PAs). However, PAs are most energy efficient close to saturation, where non-linear distortion arises. For conventional precoders, this distortion can coherently combine at user locations, limiting performance. We propose a graph neural network (GNN) to learn a mapping between channel and precoding matrices, which maximizes the sum rate affected by non-linear distortion, using a high-order polynomial PA model. In the distortion-limited regime, this GNN-based precoder outperforms zero forcing (ZF), ZF plus digital predistortion (DPD) and the distortion-aware beamforming (DAB) precoder from the state-of-the-art.
Keeping Energy-Neutral Devices Operational: a Coherent Massive Beamforming Approach
This paper investigates the potential of radio frequency (RF)-based wireless power transfer through simulations of coherent beamforming with a large array of antennas. Given the substantial number of deployed antennas, it is feasible to power numerous electronic shelf labels (ESLs) within an aisle while adhering to current regulatory constraints.
How to Perform Distributed Precoding to Wirelessly Power Shelf Labels
This study optimizes energy delivery in RF wireless power transfer (WPT) systems by adjusting precoding weights within specific time slots to meet the energy needs of Energy Receivers (ERs) while minimizing transmit power. It compares unsynchronized (non-coherent) and synchronized (coherent) systems. Experimental validation with an 84-antenna testbed confirmed the numerical simulation trends.
Information-Theoretic Study of Time-Domain Energy-Saving Techniques in Radio Access
Reduction of wireless network energy consumption is becoming increasingly important to reduce environmental footprint and operational costs. A key concept to achieve it is the use of lean transmission techniques that dynamically (de)activate hardware resources as a function of the load. In this paper, we propose a pioneering information-theoretic study of time-domain energy-saving techniques, relying on a practical hardware power consumption model of sleep and active modes. By minimizing the power consumption under a quality of service constraint (rate, latency), we propose simple yet powerful techniques to allocate power and choose which resources to activate or to put in sleep mode. It is shown how consumption can be made linear with the load and achieve massive energy reduction (factor of 10) at low-to-medium load.