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 Low Power Wide Area networks (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. We demonstrate that a cross-layer approach significantly improves energy efficiency and overall throughput. Two major contributions are made. First, an open-source LPWAN assessment framework has been conceived. It allows testing and evaluating hypotheses and schemes. Secondly, as a representative case, the LoRaWAN protocol is assessed. The findings indicate how a cross-layer approach can optimize LPWANs in terms of energy efficiency and throughput. For instance, it is shown that the use of larger payloads can reduce up to three times the energy consumption on quasi-static channels yet may bring an energy penalty under adverse dynamic conditions

High Precision Hybrid RF and Ultrasonic Chirp-based Ranging for Low-Power IoT Nodes

Hybrid acoustic-RF systems offer excellent ranging accuracy, yet they typically come at a power consumption that is too high to meet the energy constraints of mobile IoT nodes. We combine pulse compression and synchronized wake-ups to achieve a ranging solution that limits the active time of the nodes to 1 ms. Hence, an ultra low-power consumption of 9.015 {\mu}W for a single measurement is achieved. Measurements based on a proof-of-concept hardware platform show median distance error values below 10 cm. Both simulations and measurements demonstrate that the accuracy is reduced at low signal-to-noise ratios and when reflections occur. We introduce three methods that enhance the distance measurements at a low extra processing power cost. Hence, we validate in realistic environments that the centimeter accuracy can be obtained within the energy budget of mobile devices and IoT nodes. The proposed hybrid signal ranging system can be extended to perform accurate, low-power indoor positioning.Comment: 19 pages, 18 figures, 5 table

Flexible Design of a High-Radix Modular Simultaneous Exponentiation Core

status: publishe

Study and Design of a Reusable Embedded Hardware Architecture for Secure Wireless Communication (Studie en ontwerp van een herbruikbare ingebedde hardware architectuur voor veilige draadloze communicatie)

The proliferation of wireless embedded devices and the boom of related applications have set design engineers the difficult task of supporting security for these emerging applications. This encompasses hiding a user's sensitive data, safeguarding his privacy and authenticating communicating parties as well as the data that is being exchanged. Implementing these security measures in an embedded context requires a multidisciplinary approach and often forces designers to make a trade-off between, processing speed, memory usage, energy, cost, etc., which are not only influenced by the security measures itself, but also by the application and the communication.In this PhD, we have developed an embedded test platform that allows design engineers to quickly implement proof-of-concept applications, evaluate them, and make educated design choices on how to implement the required security measures. As an addition to this platform we have designed a hardware accelerator for offloading the modular exponentiations required for several public-key security protocols. To keep the range of possible applications and hardware platforms as broad as possible, we have made this design highly customizable. A second topic is the study of Near-Field Communication (NFC) as a medium to communicate between a mobile device (e.g., a tablet or smartphone) and an embedded terminal (e.g., a vending machine, access control point, or ticketing terminal). We also extend the functionality of our embedded test platform by adding support for NFC.Finally, we have used our embedded platform in two case studies to validate our design and to evaluate different design approaches in a practical setup. A first case study focuses on attribute-based credential verification (a privacy-preserving technique) over NFC and evaluates the influence of communication and processing (both in hardware and software) on the application run time. A second case study evaluates the data rates and communication times of NFC compared to an approach in which NFC is used to initiate communication over a faster WiFi channel.status: publishe

Op grote schaal inpluggen en netwerken maar

status: publishe

Modular Simultaneous Exponentiation IP Core Specification

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An Improved 2D Triangulation Algorithm for Use With Linear Arrays

When localization is required to offer location-based services in user-centered applications, then (acoustic) angle-of-arrival (AOA) can be an energy efficient and user friendly option. Previous research has always assumed that a priori knowledge can be used to select the correct angles out of a set of possible values as an input to the AOA localization algorithm. In this paper, we propose an algorithm that is able to perform this selection automatically with a high chance of selecting the correct values. Even for an increasing standard deviation on the measured angles, the localization accuracy of the proposed algorithm is able to compete with an algorithm that does the selection based on a priori knowledge.status: publishe

Location awareness enables autonomous commissioning in wireless sensor networks

For large-scale wireless networks, the deployment of new systems can be a costly and tedious task. In this article we show how this effort can be reduced by automating the configuration of new wireless devices, based on their location. This technique is useful in e.g. home automation systems where a light switch needs to be paired with the light fixtures. To show how our system works, we have implemented a demonstrator application based on Bluetooth Low Energy. We assume that each room contains a beacon node that holds the settings for that room. Based on the RSSI in the BLE advertisements of those node, a new node can detect in which room it is deployed and update its own settings accordingly. A node can do this correctly in 96% of the case. To improve the reliability, a node can ask the user to confirm its position, whenever there is doubt. This happens in 12% of the cases, resulting in 100% correct localizations.status: publishe