Research Focus

The research focus of the DES-Testbed is primarily on the experimental comparison of simulations and real world implementations. As recent publications showed, there is still a severe difference in the results obtained from simulation environments compared to real world experiments. Most network simulators abstract from the wireless medium and do not consider an operating system being used on real hardware. The properties of the operating system, especially scheduling strategies and multi-threading, can affect the behavior of the algorithms and therefore influence the experiment outcome. Additionally, the architecture of the network protocol stacks has to be considered. When implementing algorithms on real hardware, the Application Programming Interface (API) of the underlying operating system kernel has to be used. In a simulation environment however, there are no restrictions for the implementations. With the help of the DES-Testbed we are evaluating routing algorithms in order to get information that can be used in real world scenarios and improve everyday life applications, for example providing internet access in rural areas that lack a wired infrastructure.

Next to these research activities is the combination of sensor nodes and mesh routers based on IEEE 802.11 yielding further novel opportunities. The two components form two coexistent testbeds and take advantage of the features arising from the hybrid approach. The sensor nodes provide an additional network interface to the mesh routers and therefore offer channels in the ISM frequency band that are orthogonal to IEEE 802.11. Additionally, the MSB-A2 boards can be equipped with a multitude of sensors and actors that can also be utilized by the mesh routers.

Similarly, the sensor nodes exploit the hybrid infrastructure to establish virtual connections with far away nodes using the Ethernet backbone. The wired connection also provides an additional reliable packet loss detection mechanism. The constraint of limited power resources can be simulated by measuring the power consumption and shutting off nodes if a certain threshold is exceeded.

Finally, the DES-Testbed is used in daily teaching activities giving students the opportunity to apply their knowledge attained in classes.