Richard Verhoeven

An Integral Approach to Programming Sensor Networks

In this paper we present a complete approach to programming sensor networks. The main contribution concerns the separation of three abstraction levels, viz., application level, network level and node level, leaving more room for standardization than with current practices. In addition we propose to program the network from an overall perspective rather than programming individual nodes. The proposed model is event-based, corresponding closely to the nature of wireless sensors and admits content-based addressing of nodes and groups of nodes. The paper describes how the three abstraction levels come together and gives examples of the approach at all three levels.

Defining services for mobile terminals using remote user interfaces

CE devices are increasingly extended with network support, such that the devices can be monitored or controlled remotely. At the same time, mobile phones are extended with additional network technologies, such that they can connect directly to the other devices. The use of a mobile phone as a generic remote control is investigated with a focus on the user interface (UI). Existing technologies are limited in their capabilities and user interaction models, that is, (one- way) page-based or form-based interaction. The UI fragments protocol, described in this article, has the advantages that it allows for better interaction between the user and the device (due to incremental updates, and two-way communication), and that it is an independent device (due to the use of abstract UI descriptions, in conjunction with hierarchical style sheets).

Smart indoor solid state lighting based on a novel illumination model and implementation

Smart lighting research traditionally focuses on conventional incandescent and fluorescent luminaries. However, in addition to its higher energy efficiency and longer lifetime, Solid State Lighting (SSL) offers better control of spectral, spatial, temporal polarization, and color properties of light. Combined with the recent developments in smart environments research, SSL utilizing Light Emitting Diodes (LED) creates a new playground for user-light interaction. We present a novel illumination model for SSL and implement this model on a wireless sensor network (WSN). The light sensors and actuators in the WSN provide services for sensing illumination changes and dynamically adjusting luminary brightness according to user preferences. Experiments conducted two key scenarios, i.e. reading and watching TV, show that the preferred illumination levels in an activity space can be achieved and maintained, irrespective of external light variations.

Gateway architectures for service oriented application-level gateways

In this paper we present lightweight and generic application level gateways for connecting service oriented sensor networks to service oriented standards in the consumer electronics domain. We study the trade-offs between interface richness, deployment granularity and overhead in discovery protocols and we present how the varying interaction patterns on both sides of the gateway can be efficiently mapped onto each other. As a result we obtain three different application-level gateways architectures. The analysis is kept concrete using the Open Service Architecture for Sensors and Universal Plug and Play (UPnP).

VICSDA: using virtual communities to secure service discovery and access

Service Oriented Architecture (SOA) is emerging as an enabling technology for sharing distributed heterogeneous resources on the network. Consequently, securing services is an increasing concern. Research issues include privacy protection for service providers, transparent access control for service consumers, secure service discovery and composition. In this paper, we present an access control approach which uses virtual communities to secure service discovery and access (VICSDA). Services grouped in virtual communities can only be discovered and accessed by authenticated community members. Meanwhile, services are autonomous to define their local access control policy. Moreover, behavior of these autonomous services is monitored in order to guarantee a better QoS provision. Using a virtual community overlay network on top of a SOA infrastructure, VICSDA can provide authentication, message confidentiality and integrity to secure service discovery and access. Better application performance can be achieved through VICSDA. We integrated VICSDA with a 3D video streaming application. This example provides us with some initial evidence that VICSDA is a viable solution to our target problems.

A Body Sensor Platform for concurrent applications

This paper presents a Body Sensor Platform supporting concurrent applications that share resources and data. Concerns are application isolation, data privacy and platform trustworthiness in view of dynamic loading of applications. A prototype has been built on commercial-off-the-shelf hardware. The platform is evaluated through a case study of two sensor applications that interact with each other and share data, viz., posture detection and activity monitoring.

Toward a security model for a body sensor platform

Body Sensor Networks (BSNs) are used in the ubiquitous healthcare to measure human body functions like vital physiological data (e.g. heart beat). As the privacy-sensitive sensor data are transferred over the unreliable wireless connection and can be shared among various BSN applications, it is necessary to protect this data against potential threats. The purpose of this paper is to introduce an approach to design a lightweight security model with respect to limited resource constraints of our special purpose sensor platform.

Semantic interoperability in a heterogeneous smart lighting system

Smart spaces typically consist of collaborating heterogeneous nodes with various resource capacities, e.g. processing, memory, storage, energy capabilities. Low capacity nodes can operate using very simple protocols, allowing them to provide and consume only simple services, as opposed to devices with higher capacity, which are not limited by such constraints. Providing seamless connection and collaboration between low and high capacity nodes, i.e. interoperability, remains a challenge. This paper presents an approach for interoperability among nodes of a smart lighting system via a gateway node considering nodes of two platforms: low capacity wireless light sensors and actuators on the one hand and high capacity Smart-M3 nodes on the other hand. The gateway node is able to communicate over heterogeneous networks using different communication protocols, transferring light model information between the smart space nodes.

The WASP Architecture for Wireless Sensor Networks

This paper presents some intermediate results of the EU-IST project WASP that aims to develop an integrated model for implementing applications using wireless sensor networks. In this paper we present our approach to programming sensor networks. The main contribution concerns the separation of three abstraction levels leaving more room for standardization than with current practices. In addition, we propose to program the network from an overall perspective rather than programming individual nodes. For doing this we present two programming models that complement one another. The proposed programming model is event-based, corresponding closely to the nature of wireless sensors. The paper shows our approaches by giving several examples and ends with a description of wireless sensor networks related services and gives an outlook on future work.

Proxy support for service discovery using mDNS/DNS-SD in low power networks

We present a solution for service discovery of resource constrained devices based on mDNS/DNS-SD. We extend the mDNS/DNS-SD service discovery protocol with support for proxy servers. Proxy servers temporarily store information about services offered on resource constrained devices and respond on their behalf while they are not available. We analyze two protocols for the delegation mechanism between a service provider and a proxy server: an active proxy protocol, as used in the mDNS/DNS-SD implementation by Apple, and a new, passive proxy protocol. We implement and simulate both approaches. Based on the delay and energy usage, we show that the second approach converges faster, thus saving more energy by allowing the resource constrained device to be turned off earlier.