Combining Bluetooth Mesh and KNX : the best of both worlds

Bluetooth Mesh (BT Mesh) is a promising wireless technology for building automation. At the same time, KNX is a well-established building automation system that has a vast installed base. Specifically, the strength of KNX lies in its proven semantic models. These models are the foundation for interoperability and the implementation of larger systems. The presented project demonstrates how a user can easily connect a new BT Mesh system to a well-established, wired KNX building automation system. Notably, the project achieves this through a self-developed stateless gateway, which allows controlling BT Mesh devices from the KNX network and vice versa. As a result, it is possible to leverage existing management systems from KNX building automation systems in BT Mesh networks. Furthermore, the project validates this concept using Home Assistant, a well- known open-source home automation platform and demonstrates, that heterogeneous KNX and BT Mesh systems are feasible

Ortsbestimmung von Objekten im Innenbereich über Echtzeit-Lokalisierung

Im Aussenbereich erfolgt die Ortsbestimmung von Objekten heute meist über satellitengestützte Systeme wie GPS. Im Innern von Gebäuden gelingt dies aber auf Grund der Signaldämpfung nur sehr eingeschränkt. Dieser Artikel beschreibt eine im Innenbereich anwendbare Echtzeit-Lokalisierung, die auf gemessenen Laufzeiten von IEEE 802.15.4-Ultrawideband-Signalen (UWB) beruht

High precision real-time location estimates in a real-life barn environment using a commercial ultra wideband chip

Structural changes lead to an increase in the number of dairy cows and dry sows kept per group. This has consequences in how easily a farmer can supervise his herd and may be detrimental to animal welfare, specifically regarding social relations, time budget and area of residence. An automated tracking system can support the farmer in his management activities and can provide the foundation for a scientific assessment of the welfare consequences of large groups. In this study, a relatively simple and inexpensive real time location system (RTLS) was developed with the aim of achieving precise localization of several tags (animals) in real time and in a real barn environment. The RTLS was based on the ultra-wideband (UWB) technology provided by DecaWave and was adapted for a time difference of arrival (TDoA) procedure to estimate the tags’ positions. The RTLS can handle up to a hundred tags simultaneously using a Pure ALOHA random access method at 1-second intervals. The localization of the tags was estimated in 2D on a given fixed height using a constrained Gauss-Newton algorithm to increase accuracy and stability. The performance of the overall system was evaluated in two different dairy barns. To determine the precision of the system, static and dynamic positions measured at withers height of a cow (1.5 m) and closer to the ground mimicking a lying cow were compared with a reference system (theodolite). The 2D deviations between the systems were used as a measure of precision. In addition, the scalability in respect to the number of tags and the size of the observed area was examined in situations with ten tags and the situation with 100 tags was simulated with a ten-fold increase in sampling rate. According to the field test, the system as developed can be used for the individual localization of animals. At withers height, most of the measured locations deviated less than 0.5 m from the localizations as measured by the theodolite. At lower heights, and closer to the corners of the observed area, some localization estimates were somewhat larger. This was also the case close to large metal barn infrastructure. The measured collision rate of 11% for 100 tags was low. In spite of its low price, the system as a whole is therefore promising and ready for a next step, which should include the observation of large groups of real animals on working farms

Security on IoT devices with secure elements

The emergence of new low power IoT networks in which leaf nodes have native IPv6 connectivity and the grown awareness for data protection of IoT devices require leaf nodes to provide a higher level of security, similar to the level of a standard computer system. Especially in terms of energy consumption and device cost, the intensive cryptographic operations of well-known computer security algorithms are a big challenge for resource constrained devices. To face these challenges, semiconductor vendors have recently introduced new dedicated hardware, so called secure elements. These devices provide hardware accelerated support for cryptographic operations and tamper proof memory for the secure storage of cryptographically sensitive material. Moreover, they employ specific techniques against so called side channel attacks. The paper describes and specifies different classes of secure elements and discusses their opportunities and challenges. Furthermore, the paper provides multiple detailed examples how secure elements can be used for different applications. Finally, this paper briefly presents general measurement results from a performed evaluation with four selected secure elements from different vendors. A more complete report about the performed evaluation will be presented in a following paper. The purpose of this paper is to introduce the concept of secure elements and provide a generic overview of their features, serving as starting point to work with secure elements

Using secure microcontrollers in IoT applications

Security in IoT devices is a major topic that IoT is facing. Rising awareness from the customer side and up-coming regulations will force manufacturers to increase the level of security on their IoT devices. Particularly, it is a challenge to leverage the elaborate, well-known computer security algorithms to resource-constrained IoT devices. For the Cortex-A processors Arm® has already introduced their security extension TrustZone® for quite a while. With the new generation of secure microcontrollers, Arm® TrustZone® is now available for battery-powered IoT devices. Furthermore, these secure microcontrollers provide additional security features, such as hardware accelerators for cryptographic operations, secure key storage, and sophisticated random number generators, therefore, increasing security on resource-constrained IoT devices. The paper introduces the concept of these new secure microcontrollers and provides an overview of their features, by showing an application example that covers the topics of secure boot and the usage of TrustZone®. Furthermore, the paper presents energy measurements of the implemented example comparing them to the execution on conventional microcontrollers without TrustZone®. Finally, the paper summarizes advantages and weaknesses of secure microcontrollers compared to dedicated off-chip solutions like secure elements

Low-power wireless : what is possible with Wi-Fi?

Various chip vendors are offering low-power Wi-Fi solutions for embedded applications. These systems contain integrated TCP/IP stacks. They feature specific operation modes to minimize energy consumption of battery operated devices targeting applications in the internet-of-things area. The paper presents measurement results with regard to energy consumption. The results are used to compare the solutions of several chip vendors for selected use cases

Unique Sink Orientations of Grids

We introduce unique sink orientations of grids as digraph models for many well-studied problems, including linear programming over products of simplices, generalized linear complementarity problems over P-matrices (PGLCP), and simple stochastic games. We investigate the combinatorial structure of such orientations and develop randomized algorithms for finding the sink. We show that the orientations arising from PGLCP satisfy the Holt-Klee condition known to hold for polytope digraphs, and we give the first expected linear-time algorithms for solving PGLCP with a fixed number of block

Achievable data rates on simultaneously connected bluetooth low energy devices

Bluetooth Low Energy (BLE) has been optimized for low power and targets low data rate applications. However, there are applications where several peripherals are simultaneously connected to a central device, with the requirement of achieving moderate data rates for each connection. Available hardware and software stacks place limitations on the number of simultaneous connections as well as on the achievable data rates. This paper presents measurement results for different scenarios. On the central device side the explored options cover tablets based on Android and iOS as well as dongles that can be connected through a USB port. On the peripheral side several selected hardware set-ups (chips and modules) are measured and compared. Analysis of captured packets provides insight into why the reached data rates are often significantly lower than theoretically expected