This page has only limited features, please log in for full access.
Advances in energy efficient electronic components create new opportunities for wireless acoustic sensor networks. Such sensors can be deployed to localize unwanted and unexpected sound events in surveillance applications, home assisted living, etc. This research focused on a wireless acoustic sensor network with low-profile low-power linear MEMS microphone arrays, enabling the retrieval of angular information of sound events. The angular information was wirelessly transmitted to a central server, which estimated the location of the sound event. Common angle-of-arrival localization approaches use triangulation, however this article presents a way of using angular probability density functions combined with a matching algorithm to localize sound events. First, two computationally efficient delay-based angle-of-arrival calculation methods were investigated. The matching algorithm is described and compared to a common triangulation approach. The two localization algorithms were experimentally evaluated in a 4.25 m by 9.20 m room, localizing white noise and vocal sounds. The results demonstrate the superior accuracy of the proposed matching algorithm over a common triangulation approach. When localizing a white noise source, an accuracy improvement of up to 114% was achieved.
Bart Thoen; Stijn Wielandt; Lieven De Strycker. Improving AoA Localization Accuracy in Wireless Acoustic Sensor Networks with Angular Probability Density Functions. Sensors 2019, 19, 900 .
AMA StyleBart Thoen, Stijn Wielandt, Lieven De Strycker. Improving AoA Localization Accuracy in Wireless Acoustic Sensor Networks with Angular Probability Density Functions. Sensors. 2019; 19 (4):900.
Chicago/Turabian StyleBart Thoen; Stijn Wielandt; Lieven De Strycker. 2019. "Improving AoA Localization Accuracy in Wireless Acoustic Sensor Networks with Angular Probability Density Functions." Sensors 19, no. 4: 900.
Many commercial platforms for fast prototyping have gained support for lpwan technologies. However, these solutions do not meet the low-cost and low-power requirements for a large-scale distribution of battery-powered sensor nodes. This paper presents the design, realization and validation of an open-source lpwan versatile platform. Energy and cost are considered key constraints for this hardware design. A power-efficient LoRa radio interface is implemented by hosting MAC functionality on the application microcontroller, eliminating the need for a modem. In the system architecture, power and cost savings are obtained by omitting and controlling lossy power circuitry. The resulting platform allows entry-level prototyping, while featuring an ultra-low sleep power of 25.2 μ W . This makes lpwan sensor applications accessible in domains that would otherwise require custom hardware development. The proposed design is validated by an illustrative but functional example of sensor nodes deployed in the field.
Bart Thoen; Gilles Callebaut; Guus Leenders; Stijn Wielandt. A Deployable LPWAN Platform for Low-Cost and Energy-Constrained IoT Applications. Sensors 2019, 19, 585 .
AMA StyleBart Thoen, Gilles Callebaut, Guus Leenders, Stijn Wielandt. A Deployable LPWAN Platform for Low-Cost and Energy-Constrained IoT Applications. Sensors. 2019; 19 (3):585.
Chicago/Turabian StyleBart Thoen; Gilles Callebaut; Guus Leenders; Stijn Wielandt. 2019. "A Deployable LPWAN Platform for Low-Cost and Energy-Constrained IoT Applications." Sensors 19, no. 3: 585.
Matthew Giorgis Anderson; Arno Thielens; Stijn Wielandt; Ali Niknejad; Jan Rabaey. Ultralow-Power Radio Frequency Beamformer Using Transmission-Line Transformers and Tunable Passives. IEEE Microwave and Wireless Components Letters 2019, 29, 158 -160.
AMA StyleMatthew Giorgis Anderson, Arno Thielens, Stijn Wielandt, Ali Niknejad, Jan Rabaey. Ultralow-Power Radio Frequency Beamformer Using Transmission-Line Transformers and Tunable Passives. IEEE Microwave and Wireless Components Letters. 2019; 29 (2):158-160.
Chicago/Turabian StyleMatthew Giorgis Anderson; Arno Thielens; Stijn Wielandt; Ali Niknejad; Jan Rabaey. 2019. "Ultralow-Power Radio Frequency Beamformer Using Transmission-Line Transformers and Tunable Passives." IEEE Microwave and Wireless Components Letters 29, no. 2: 158-160.
While there exists a wide variety of radio frequency (RF) technologies amenable for usage in Wireless Body Area Networks (WBANs), which have been studied separately before, it is currently still unclear how their performance compares in true on-body scenarios. In this paper, a single reference on-body scenario—that is, propagation along the arm—is used to experimentally compare six distinct RF technologies (between 420 MHz and 2.4 GHz) in terms of path loss. To further quantify on-body path loss, measurements for five different on-body scenarios are presented as well. To compensate for the effect of often large path losses, two mitigation strategies to (dynamically) improve on-body links are introduced and experimentally verified: beam steering using a phased array, and usage of on-body RF repeaters. The results of this study can serve as a tool for WBAN designers to aid in the selection of the right RF frequency and technology for their application.
Arno Thielens; Robin Benarrouch; Stijn Wielandt; Matthew G. Anderson; Ali Moin; Andreia Cathelin; Jan M. Rabaey. A Comparative Study of On-Body Radio-Frequency Links in the 420 MHz–2.4 GHz Range. Sensors 2018, 18, 4165 .
AMA StyleArno Thielens, Robin Benarrouch, Stijn Wielandt, Matthew G. Anderson, Ali Moin, Andreia Cathelin, Jan M. Rabaey. A Comparative Study of On-Body Radio-Frequency Links in the 420 MHz–2.4 GHz Range. Sensors. 2018; 18 (12):4165.
Chicago/Turabian StyleArno Thielens; Robin Benarrouch; Stijn Wielandt; Matthew G. Anderson; Ali Moin; Andreia Cathelin; Jan M. Rabaey. 2018. "A Comparative Study of On-Body Radio-Frequency Links in the 420 MHz–2.4 GHz Range." Sensors 18, no. 12: 4165.
Indoor localization of unknown acoustic events with MEMS microphone arrays have a huge potential in applications like home assisted living and surveillance. This article presents an Angle of Arrival (AoA) fingerprinting method for use in Wireless Acoustic Sensor Networks (WASNs) with low-profile microphone arrays. In a first research phase, acoustic measurements are performed in an anechoic room to evaluate two computationally efficient time domain delay-based AoA algorithms: one based on dot product calculations and another based on dot products with a PHAse Transform (PHAT). The evaluation of the algorithms is conducted with two sound events: white noise and a female voice. The algorithms are able to calculate the AoA with Root Mean Square Errors (RMSEs) of 3.5° for white noise and 9.8° to 16° for female vocal sounds. In the second research phase, an AoA fingerprinting algorithm is developed for acoustic event localization. The proposed solution is experimentally verified in a room of 4.25 m by 9.20 m with 4 acoustic sensor nodes. Acoustic fingerprints of white noise, recorded along a predefined grid in the room, are used to localize white noise and vocal sounds. The localization errors are evaluated using one node at a time, resulting in mean localization errors between 0.65 m and 0.98 m for white noise and between 1.18 m and 1.52 m for vocal sounds.
Bart Thoen; Stijn Wielandt; Lieven De Strycker. Fingerprinting Method for Acoustic Localization Using Low-Profile Microphone Arrays. 2018 International Conference on Indoor Positioning and Indoor Navigation (IPIN) 2018, 1 -7.
AMA StyleBart Thoen, Stijn Wielandt, Lieven De Strycker. Fingerprinting Method for Acoustic Localization Using Low-Profile Microphone Arrays. 2018 International Conference on Indoor Positioning and Indoor Navigation (IPIN). 2018; ():1-7.
Chicago/Turabian StyleBart Thoen; Stijn Wielandt; Lieven De Strycker. 2018. "Fingerprinting Method for Acoustic Localization Using Low-Profile Microphone Arrays." 2018 International Conference on Indoor Positioning and Indoor Navigation (IPIN) , no. : 1-7.
Indoor positioning systems are mostly supported by Radio Frequency (RF) technologies, due to the omnipresence of wireless communication infrastructure and handsets. Most of these localization systems rely on a Line Of Sight (LOS) connection to calculate a position based on signal strength, delay or direction. However, indoor environments are characterized by Non Line Of Sight (NLOS) connections and multipath effects such as reflections, scattering, diffraction and refraction. Multipath components are generally considered as undesirable and therefore most techniques focus on mitigation. This research applies an Angle of Arrival (AoA) multipath assistance approach, using ray tracing in a known environment to exploit signal reflections. Because the complete propagation channel is taken into account, a mobile node can already be localized by a single fixed antenna array. In order to assess the performance of the system, LOS and NLOS experiments are performed in three indoor environments in the 2.4 GHz and 5 GHz frequency bands. All measurements are processed by the multipath assisted AoA method, as well as a standard triangulation approach. These tests indicate the superior accuracy of the multipath assisted method, especially in NLOS conditions. Also, the tests demonstrate that the systems performs significantly better at 2.4 GHz than at 5 GHz. Finally, the performance of the presented system is compared to results that can be found in related work.
Stijn Wielandt; Bart Thoen; Lieven De Strycker. Experimental Evaluation of a Single Anchor Multipath Assisted Indoor Angle of Arrival Localization System in the 2.4 GHz and 5 GHz Band. 2018 International Conference on Indoor Positioning and Indoor Navigation (IPIN) 2018, 1 -7.
AMA StyleStijn Wielandt, Bart Thoen, Lieven De Strycker. Experimental Evaluation of a Single Anchor Multipath Assisted Indoor Angle of Arrival Localization System in the 2.4 GHz and 5 GHz Band. 2018 International Conference on Indoor Positioning and Indoor Navigation (IPIN). 2018; ():1-7.
Chicago/Turabian StyleStijn Wielandt; Bart Thoen; Lieven De Strycker. 2018. "Experimental Evaluation of a Single Anchor Multipath Assisted Indoor Angle of Arrival Localization System in the 2.4 GHz and 5 GHz Band." 2018 International Conference on Indoor Positioning and Indoor Navigation (IPIN) , no. : 1-7.
Indoor radio frequency positioning systems enable a broad range of location aware applications. However, the localization accuracy is often impaired by Non-Line-Of-Sight (NLOS) connections and indoor multipath effects. An interesting evolution in widely deployed communication systems is the transition to multi-antenna devices with beamforming capabilities. These properties form an opportunity for localization methods based on Angle of Arrival (AoA) estimation. This work investigates how multipath propagation can be exploited to enhance the accuracy of AoA localization systems. The presented multipath assisted method resembles a fingerprinting approach, matching an AoA measurement vector to a set of reference vectors. However, reference data is not generated by labor intensive site surveying. Instead, a ray tracer is used, relying on a-priori known floor plan information. The resulting algorithm requires only one fixed receiving antenna array to determine the position of a mobile transmitter in a room. The approach is experimentally evaluated in LOS and NLOS conditions, providing insights in the accuracy and robustness. The measurements are performed in various indoor environments with different hardware configurations. This leads to the conclusion that the proposed system yields a considerable accuracy improvement over common narrowband AoA positioning methods, as well as a reduction of setup efforts in comparison to conventional fingerprinting systems.
Stijn Wielandt; Lieven De Strycker. Indoor Multipath Assisted Angle of Arrival Localization. Sensors 2017, 17, 2522 .
AMA StyleStijn Wielandt, Lieven De Strycker. Indoor Multipath Assisted Angle of Arrival Localization. Sensors. 2017; 17 (11):2522.
Chicago/Turabian StyleStijn Wielandt; Lieven De Strycker. 2017. "Indoor Multipath Assisted Angle of Arrival Localization." Sensors 17, no. 11: 2522.
Location prevails as a piece of crucial information for decision-making processes. Whereas positioning in outdoor environments can be mainly attributed to Global Navigation Satellite Systems, no single technology can be appointed for accurate indoor localization. Many approaches exist, mostly relying on line-of-sight propagation from a mobile node to multiple anchor nodes. These solutions not only require complex installations, but in many cases they also make inapplicable assumptions about indoor environments. This paper investigates an indoor localization system with a single anchor node, estimating the position of an omnidirectional mobile transmitter by fingerprinting angle of arrival data. Measurements were taken with a 10-elements uniform linear antenna array at a 2.47 GHz carrier frequency. Three different scenarios were defined for the evaluation of localization errors and the influence of spatial smoothing, a technique for signal decorrelation.
Stijn Wielandt; Manish Vikash Shah; Nazeer Akram Athaullah; Uzair Mubarak Sayyad; Ravi Bhushan Yadav; Rahul Mahesh Dharamdasani; Lieven De Strycker; Michael Kuhn. 2.4 GHz single anchor node indoor localization system with angle of arrival fingerprinting. 2017 Wireless Days 2017, 152 -154.
AMA StyleStijn Wielandt, Manish Vikash Shah, Nazeer Akram Athaullah, Uzair Mubarak Sayyad, Ravi Bhushan Yadav, Rahul Mahesh Dharamdasani, Lieven De Strycker, Michael Kuhn. 2.4 GHz single anchor node indoor localization system with angle of arrival fingerprinting. 2017 Wireless Days. 2017; ():152-154.
Chicago/Turabian StyleStijn Wielandt; Manish Vikash Shah; Nazeer Akram Athaullah; Uzair Mubarak Sayyad; Ravi Bhushan Yadav; Rahul Mahesh Dharamdasani; Lieven De Strycker; Michael Kuhn. 2017. "2.4 GHz single anchor node indoor localization system with angle of arrival fingerprinting." 2017 Wireless Days , no. : 152-154.
Electronic devices for measuring body parameters in healthcare environments generally exhibit hygienic problems. Furthermore, they require regular battery replacement or recharging. This paper presents an electronic wristband for medical measurements that can be charged wirelessly. Its power supply is equipped with a Qi compatible inductive power receiver, an Electrochemical Double-Layer Capacitor (EDLC) energy buffer and a series of voltage regulators that can be disconnected from the energy buffer by a microcontroller. Because the wireless power receiver was placed behind a display, a study was performed of the effects of the display on receiver coil characteristics and system performance. For the selection of the EDLC, a selection process is presented, making a tradeoff between device autonomy and charging time. The result is a completely sealable and thus sterilizable device that can be charged in less than 5 seconds while being worn on the wrist.
Stijn Wielandt; Bart Thoen; Jean-Pierre Goemaere; Lieven De Strycker; Nobby Stevens. Inductive charging of an EDLC powered wristband device for medical measurements. 2015 European Conference on Circuit Theory and Design (ECCTD) 2015, 1 -4.
AMA StyleStijn Wielandt, Bart Thoen, Jean-Pierre Goemaere, Lieven De Strycker, Nobby Stevens. Inductive charging of an EDLC powered wristband device for medical measurements. 2015 European Conference on Circuit Theory and Design (ECCTD). 2015; ():1-4.
Chicago/Turabian StyleStijn Wielandt; Bart Thoen; Jean-Pierre Goemaere; Lieven De Strycker; Nobby Stevens. 2015. "Inductive charging of an EDLC powered wristband device for medical measurements." 2015 European Conference on Circuit Theory and Design (ECCTD) , no. : 1-4.
The performance of indoor localization systems based on angle of arrival strongly depends on the environment. Consequently, a characterization of localization errors in different environments is necessary to correctly assess the accuracy of these systems. This paper focuses on the localization errors in multiple environments using basic 2.4 GHz linear antenna arrays. First, a theoretical algorithm is elaborated to predict the expected localization error in various environments. Subsequently, this algorithm is tested in practical tests performed in an anechoic room, an empty room and a room with obstacles. In these tests, various techniques for error minimization are evaluated, as well as the Beamscan, ESPRIT and MUSIC angle of arrival algorithms. It is shown that the accuracy in an anechoic room can also be obtained in an empty room for certain configurations. This is not the case for a room with obstacles preventing line-of-sight connections. For this case, a new type of localization system is proposed.
Stijn Wielandt; Anneleen Van Nieuwenhuyse; Jean-Pierre Goemaere; Bart Nauwelaers; Lieven De Strycker. Evaluation of angle of arrival estimation for localization in multiple indoor environments. 2014 Ubiquitous Positioning Indoor Navigation and Location Based Service (UPINLBS) 2014, 36 -43.
AMA StyleStijn Wielandt, Anneleen Van Nieuwenhuyse, Jean-Pierre Goemaere, Bart Nauwelaers, Lieven De Strycker. Evaluation of angle of arrival estimation for localization in multiple indoor environments. 2014 Ubiquitous Positioning Indoor Navigation and Location Based Service (UPINLBS). 2014; ():36-43.
Chicago/Turabian StyleStijn Wielandt; Anneleen Van Nieuwenhuyse; Jean-Pierre Goemaere; Bart Nauwelaers; Lieven De Strycker. 2014. "Evaluation of angle of arrival estimation for localization in multiple indoor environments." 2014 Ubiquitous Positioning Indoor Navigation and Location Based Service (UPINLBS) , no. : 36-43.
In this paper we intend to find out what resolution can be achieved with two-dimensional Angle of Arrival localization when using linear antenna arrays at 2.4 GHz. A theoretical resolution calculation method is presented. Room dimensions, number of cooperating anchor nodes (provided with a linear antenna array) which track the position of a mobile node and number of antenna elements can be chosen. These theoretical calculations lead to the definition of a reference value which can be used to calculate the expected resolution for all rectangular shaped rooms with the desired variable settings. It is also shown that square rooms result in the best resolution and adding extra antenna elements improves the resolution. The design and calibration of a practical linear antenna array, with four linearly positioned 2.4 GHz antenna elements and inter distance of λ/2, is presented. Measurements of practical beam patterns, and the corresponding -3dB beam widths, for different incident angles show that influences such as mutual coupling and reflections can not be neglected. The practical resolutions are compared with expected theoretical values and it is shown that besides I/Q and phase offset calibration, manifold calibration is necessary.
Anneleen Van Nieuwenhuyse; Stijn Wielandt; Jean-Pierre Goemaere; Bart Nauwelaers; Lieven De Strycker. Resolving positions of coherent sources using linear antenna arrays at 2.4 GHz. 2014 Ubiquitous Positioning Indoor Navigation and Location Based Service (UPINLBS) 2014, 141 -147.
AMA StyleAnneleen Van Nieuwenhuyse, Stijn Wielandt, Jean-Pierre Goemaere, Bart Nauwelaers, Lieven De Strycker. Resolving positions of coherent sources using linear antenna arrays at 2.4 GHz. 2014 Ubiquitous Positioning Indoor Navigation and Location Based Service (UPINLBS). 2014; ():141-147.
Chicago/Turabian StyleAnneleen Van Nieuwenhuyse; Stijn Wielandt; Jean-Pierre Goemaere; Bart Nauwelaers; Lieven De Strycker. 2014. "Resolving positions of coherent sources using linear antenna arrays at 2.4 GHz." 2014 Ubiquitous Positioning Indoor Navigation and Location Based Service (UPINLBS) , no. : 141-147.
The advantages of wirelessly powering electronic devices are numerous, but the technology is generally not being applied to moving devices because existing solutions are complex or offer poor efficiency. This paper describes a wireless power system for receivers moving between uniformly distributed points in a rectangular area. The proposed solution consists of a single small wireless power transmitter, offering both low complexity and high efficiency. Simulations were performed to determine the optimal transmitter location, shape and transmitted power. Also a statistical analysis of the receiver buffer size was performed. As a result of these simulations, a design flow was proposed that permits the use of existing technologies for the considered setup.
Stijn Wielandt; Jean-Pierre Goemaere; Lieven De Strycker; Nobby Stevens. Study of wireless power systems with two-dimensionally moving receivers. 2014 IEEE Wireless Power Transfer Conference 2014, 243 -246.
AMA StyleStijn Wielandt, Jean-Pierre Goemaere, Lieven De Strycker, Nobby Stevens. Study of wireless power systems with two-dimensionally moving receivers. 2014 IEEE Wireless Power Transfer Conference. 2014; ():243-246.
Chicago/Turabian StyleStijn Wielandt; Jean-Pierre Goemaere; Lieven De Strycker; Nobby Stevens. 2014. "Study of wireless power systems with two-dimensionally moving receivers." 2014 IEEE Wireless Power Transfer Conference , no. : 243-246.
Present-day commercial wireless inductive power transfer systems rely on a low frequency alternating magnetic field, generated by a transmitter coil and picked up by a receiver coil. In general, these inductively coupled coils are perfectly aligned, in order to obtain a constant high coupling factor. In some cases though, the receiver can move on a regular basis above the transmitter. This paper discusses a method to wirelessly power a device moving on a surface. The transmitter consists of a single coil that is significantly smaller than the operation radius of the moving receiver. Therefore, the receiver is not always in the range of the transmitter and the power transfer occurs intermittent. In order to provide the receiver with a constant energy supply, a supercapacitor buffer is implemented. When the receiver approaches the transmitter, the buffer is charged in a short period of time. Furthermore, a communication channel is set up from the power receiver to the power transmitter, enabling receiver identification and power management.
Bart Thoen; Stijn Wielandt; Jeroen De Baere; Jean-Pierre Goemaere; Lieven De Strycker; Nobby Stevens. Design of an inductively coupled wireless power system for moving receivers. 2014 IEEE Wireless Power Transfer Conference 2014, 48 -51.
AMA StyleBart Thoen, Stijn Wielandt, Jeroen De Baere, Jean-Pierre Goemaere, Lieven De Strycker, Nobby Stevens. Design of an inductively coupled wireless power system for moving receivers. 2014 IEEE Wireless Power Transfer Conference. 2014; ():48-51.
Chicago/Turabian StyleBart Thoen; Stijn Wielandt; Jeroen De Baere; Jean-Pierre Goemaere; Lieven De Strycker; Nobby Stevens. 2014. "Design of an inductively coupled wireless power system for moving receivers." 2014 IEEE Wireless Power Transfer Conference , no. : 48-51.
When RFID reader antennas are placed in a parallel line configuration, proper shielding is indispensable to prevent the readout of tags in a different line. However, placing electrically conductive or magnetically permeable shielding materials in the vicinity of a loop antenna influences the magnetic field strength and self inductance of the antenna, thus affecting the readout range. This paper evaluates the effects of different shieldings on the magnetic field strength, the readout range of an RFID tag and the self inductance of the antenna. The considered shieldings consist of copper or a combination of copper with a layer of highly or lowly permeable ferrite on top. First, the influences of these materials are compared to a free space setup in FEM simulations. These results are subsequently verified in an experimental setup. The configuration with a copper plate covered with a highly permeable ferrite layer increases the magnetic field strength, readout range and self inductance of the antenna, in contrast to the other configurations. Due to the efficient shielding, erroneous readout events of tags in a parallel line are suppressed.
Stijn Wielandt; Davy Mercy; Nobby Stevens; Lieven De Strycker; Jean-Pierre Goemaere. Evaluation of shielding materials for low frequency RFID systems. International Symposium on Electromagnetic Compatibility - EMC EUROPE 2012, 1 -5.
AMA StyleStijn Wielandt, Davy Mercy, Nobby Stevens, Lieven De Strycker, Jean-Pierre Goemaere. Evaluation of shielding materials for low frequency RFID systems. International Symposium on Electromagnetic Compatibility - EMC EUROPE. 2012; ():1-5.
Chicago/Turabian StyleStijn Wielandt; Davy Mercy; Nobby Stevens; Lieven De Strycker; Jean-Pierre Goemaere. 2012. "Evaluation of shielding materials for low frequency RFID systems." International Symposium on Electromagnetic Compatibility - EMC EUROPE , no. : 1-5.