Visibility Levels: Managing the Tradeoff between Visibility and Resource Consumption

Pre-deployment tests of sensor networks in indoor testbeds can only deliver a very approximate view of the correctness and performance of a deployed sensor network and it is therefore common that after deployment problems and failures occur that could not be observed during pre-deployment tests. Finding and fixing such problems requires visibility of the system state, such that an engineer can identify causes of misbehavior. Unfortunately, exposing the internal state of sensor nodes requires resources such as communication bandwidth and energy: the better visibility of system state is required, the more resources are needed to extract that state from the sensor network. In this paper we propose a concept and tool that give the user explicit control over this tradeoff. Essentially, the user can specify a resource budget and our tool strives to provide best possible visibility while not exceeding the resource budget. We present the design of our vLevels framework and report the results of a case study demonstrating that the overhead of our approach is small and that visibility is automatically adjusted to meet the specified resource budget.