Wilfried Daniels

Energy aware software evolution for Wireless Sensor Networks

Wireless Sensor Networks (WSNs) are subject to high levels of dynamism arising from changing environmental conditions and application requirements. Reconfiguration allows software functionality to be optimized for current environmental conditions and supports software evolution to meet variable application requirements. Contemporary software modularization approaches for WSNs allow for software evolution at various granularities; from monolithic re-flashing of OS and application functionality, through replacement of complete applications, to the reconfiguration of individual software components. As the nodes that compose a WSN must typically operate for long periods on a single battery charge, estimating the energy cost of software evolution is critical. This paper contributes a generic model for calculating the energy cost of the reconfiguration in WSN. We have embedded this model in the LooCI middleware, resulting in the first energy aware reconfigurable component model for sensor networks. We evaluate our approach using two real-world WSN applications and find that (i.) our model accurately predicts the energy cost of reconfiguration and (ii.) component-based reconfiguration has a high initial cost, but provides energy savings during software evolution.

Measuring and Modeling the Energy Cost of Reconfiguration in Sensor Networks

As wireless sensor networks (WSNs) must operate for long periods on a limited power budget, estimating the energy cost of software operations is critical. Contemporary reconfiguration approaches for WSN allow for software evolution at various granularities; from reflashing of a complete software image, through replacement of complete applications, to the reconfiguration of individual software components. This paper contributes a generic model for measuring and modeling the energy cost of reconfiguration in WSN. We validate that this model is accurate in the face of different hardware platforms, software stacks, and software encapsulation approaches. We have embedded this model in the loosely coupled component infrastructure middleware, resulting in the first energy aware reconfigurable component model for sensor networks. We evaluate our approach using two real-world WSN applications and demonstrate that our model predicts the energy cost of reconfiguration with 93% accuracy. Using this model, we demonstrate that selecting the most appropriate software modularization approach is key to minimizing energy consumption.

μPnP-Mesh: The plug-and-play mesh network for the Internet of Things

Deploying and customizing networks of Internet of Things (IoT) devices remains extremely challenging. This complexity has two main sources. First, end-users must integrate diverse sensor and actuator peripherals with IoT devices to realize their application. Second, the resulting system must provide reliable mesh networking in harsh network environments at extremely low power. This paper addresses both problems by proposing μPnP-Mesh, which combines the ease of use of μPnP with the industrial performance of SmartMesh IP. μPnP provides a low-power and low-cost method for achieving plug-and-play integration of peripherals with embedded IoT devices; SmartMesh IP provides low-power reliable mesh networking. With a true plug-and-play user experience and a lifetime above 6.5 years on a pair of AA batteries, μPnP-Mesh is a ready-to-use game-changing solution for applications such as home, building and factory automation.

Hitch Hiker: A Remote Binding Model with Priority Based Data Aggregation for Wireless Sensor Networks

The aggregation of network traffic has been shown to enhance the performance of wireless sensor networks. By reducing the number of packets that are transmitted, energy consumption, collisions and congestion are minimised. However, current data aggregation schemes restrict developers to a specific network structure or cannot handle multi-hop data aggregation. In this paper, we propose Hitch Hiker, a remote component binding model that provides for multi-hop data aggregation. Hitch Hiker uses component meta-data to discover remote support component bindings and to construct a multi-hop overlay network within the free payload space of existing traffic flows. This overlay network provides end-to-end routing of low-priority traffic while using only a small fraction of the energy of standard communication. We have developed a prototype implementation of Hitch Hiker for the LooCI component model. Our evaluation shows that Hitch Hiker consumes minimal resources and that using Hitch Hiker to deliver low-priority traffic reduces energy consumption by up to 15%.

Hitch Hiker 2.0: a binding model with flexible data aggregation for the Internet-of-Things

Wireless communication plays a critical role in determining the lifetime of Internet-of-Things (IoT) systems. Data aggregation approaches have been widely used to enhance the performance of IoT applications. Such approaches reduce the number of packets that are transmitted by combining multiple packets into one transmission unit, thereby minimising energy consumption, collisions and congestion. However, current data aggregation schemes restrict developers to a specific network structure or cannot handle multi-hop data aggregation. In this paper, we propose Hitch Hiker 2.0, a component binding model that provides support for multi-hop data aggregation. Hitch Hiker uses component meta-data to discover remote component bindings and to construct a multi-hop overlay network within the free payload space of existing traffic flows. Hitch Hiker 2.0 provides end-to-end routing of low-priority traffic while using only a small fraction of the energy of standard communication. This paper extends upon our previous work by incorporating new mechanisms for decentralised route discovery and providing additional application case studies and evaluation. We have developed a prototype implementation of Hitch Hiker for the LooCI component model. Our evaluation shows that Hitch Hiker consumes minimal resources and that using Hitch Hiker to deliver low-priority traffic reduces energy consumption by up to 32 %.

Demonstration of MicroPnP: The Zero-Configuration Wireless Sensing and Actuation Platform

Creating, deploying and configuring applications for Internet of Things (IoT) scenarios today remains complex and costly for many users. The MicroPnP platform addresses this complexity problem and provides a true zero-configuration and standards-based solution that radically reduces the cost of acquiring, building, and operating wireless sensing and actuation IoT systems at scale. MicroPnP combines true Plug-and-Play integration of sensing and actuation peripherals with ultra-reliable wireless mesh networking and extreme battery lifetimes. MicroPnP was awarded in an international IoT competition, and is currently being successfully used in commercial IoT scenarios.

Safe reparametrization of component-based WSNs

Modern Wireless Sensor Networks are moving from singe-purpose custom built solutions towards multi-purpose application hosting platforms. These platforms support multiple concurrent applications managed by multiple actors. Reconfigurable component-models are a viable solution for supporting these scenarios by reducing management and development overhead while promoting software reuse. However, implicit parameter dependencies spanning component compositions make reconfiguration complex and error-prone. This paper proposes composition-safe reparametrization of components. This is accomplished by offering language annotations that allow component developers to make dependencies explicit and network protocols to resolve and enforce parameter constraints. Our approach greatly simplifies reparametrization while imposing minimal runtime overhead.

SPEED: Secure Provable Erasure for Class-1 IoT Devices

The Internet of Things (IoT) consists of embedded devices that sense and manage our environment in a growing range of applications. Large-scale IoT systems such as smart cities require significant investment in both equipment and personnel. To maximize return on investment, IoT platforms should support multiple third-party applications and adaptation of infrastructure over time. Realizing the vision of shared IoT platforms demands strong security guarantees. That is particularly challenging considering the limited capability and resource constraints of many IoT devices. In this paper, we present SPEED, an approach to secure erasure with verifiability in IoT. Secure erasure is a fundamental property when it comes to share an IoT platform with other users which guarantees the cleanness of a devices memory at the beginning of the application deployment as well as at the time of releasing the underlying IoT device. SPEED relies on two security primitives: memory isolation and distance bounding protocol. We evaluate the performance of SPEED by implementing it on a simple bare-metal IoT device belongs to Class-1. Our evaluation results show a limited overhead in terms of memory footprint, time, and energy consumption.

S μ V - the security microvisor: a virtualisation-based security middleware for the internet of things

The Internet of Things (IoT) creates value by connecting digital processes to the physical world using embedded sensors, actuators and wireless networks. The IoT is increasingly intertwined with critical industrial processes, yet contemporary IoT devices offer limited security features, creating a large new attack surface and inhibiting the adoption of IoT technologies. Hardware security modules address this problem, however, their use increases the cost of embedded IoT devices. Furthermore, millions of IoT devices are already deployed without hardware security support. This paper addresses this problem by introducing a Security MicroVisor (SμV) middleware, which provides memory isolation and custom security operations using software virtualisation and assembly-level code verification. We showcase SμV by implementing a key security feature: remote attestation. Evaluation shows extremely low overhead in terms of memory, performance and battery lifetime for a representative IoT device.

Refraction: Low-Cost Management of Reflective Meta-Data in Pervasive Component-Based Applications

This paper proposes the concept of refraction, a principled means to lower the cost of managing reflective meta-data for pervasive systems. While prior work has demonstrated the benefits of reflective component-based middleware for building open and reconfigurable applications, the cost of using remote reflective operations remains high. Refractive components address this problem by selectively augmenting application data flows with their reflective meta-data, which travels at low cost to refractive pools, which serve as loci of inspection and control for the distributed application. Additionally reactive policies are introduced, providing a mechanism to trigger reconfigurations based on incoming reflective meta-data. We evaluate the performance of refraction in a case-study of automatic configuration repair for a real-world pervasive application. We show that refraction reduces network overhead in comparison to the direct use of reflective operations while not increasing development overhead. To enable further experimentation with the concept of refraction, we provide RxCom, an open-source refractive component model and supporting runtime environment.