Royan Ong

Environmental sensor networks

The developments in wireless network technology and miniaturization makes it possible to realistically monitor the natural environment. Within the field of environmental sensor networks, domain knowledge is an essential fourth component. Before designing and installing any system, it is necessary to understand its physical environment and deployment in detail. Sensor networks are designed to transmit data from an array of sensors to a server data repository. They do not necessarily use a simple one way data stream over a communication network rather elements of the system decide what data to pass on, using local area summaries and filtering to minimize power use while maximizing the information content. The Envisense Glacs Web project is developing a monitoring system for a glacial environment. Monitoring the ice caps and glaciers provides valuable information about the global warming and climate change.

Glacsweb: a sensor network for hostile environments

A sensor network is described which obtains data from nodes on and inside glaciers. Power management through scheduling and selective control is used to allow a lifetime of at least one year on batteries. Radio links in the glacier and across 2.5 km distances are used for data and commands. The prototype system was installed in Norway in 2003 and this paper describes details of the full design for 2004 through discussion of the lessons learnt.

Deploying a Wireless Sensor Network in Iceland

A wireless sensor network deployment on a glacier in Iceland is described. The system uses power management as well as power harvesting to provide long-term environment sensing. Advances in base station and sensor node design as well as initial results are described.

A comparison of software-based techniques intended to increase the reliability of embedded applications in the presence of EMI

Abstract Corruption of the instruction pointer in an embedded computer system has been shown to be a common failure mode in the presence of electromagnetic interference, and previous investigators have suggested that the use of techniques such as ‘Function Tokens’ (FT) and ‘NOP Fills’ (NF) can reduce the impact of such failures. In this paper, both a statistical analysis and empirical tests of code from an embedded application are used to assess and compare these techniques. Two main results are presented. First, it is demonstrated that claims about the effectiveness of FT may neither be well founded nor generally applicable; specifically, it is concluded that rather than increasing system reliability, the use of FT will have the opposite effect. Second, it is demonstrated that NF may be easily applied in most embedded applications, and that the use of this approach can have a positive impact on system reliability.

The impact of instruction pointer corruption on program flow: A computational modelling study

Abstract Corruption of the instruction pointer, the main cause of program flow errors, is a common failure mode in the presence of high levels of electromagnetic interference. In this paper, results from a sub-cycle level simulator intended to provide an insight into the impact of EMI on such systems are described, and a detailed model of the impact on EMI on embedded processors is presented.

A Sensor Network for Glaciers

This chapter reports on the design, implementation and results from GlacsWeb, an environmental sensor network for glaciers installed in Summer 2004 at Briksdalsbreen, Norway. The importance of power control, hardware architecture and communication systems are discussed and research issues highlighted.