Tuning the Epidemical Algorithm in Wireless Sensor Networks

We discuss the networking dimension of the Integrated Platform for Autonomic Computing (IPAC). IPAC supports the development and running of fully distributed applications that rely on infrastructureless (ad-hoc) network with multi-hop transmission capabilities. Such environment is typically used for the realization of collaborative context awareness where nodes with sensors “generate” and report context while other nodes receive and “consume” such information (i.e., feed local applications with it). Due to its highly dynamic character this application environment, an efficient solution for the dissemination of information within the network involves the adoption of epidemical algorithms. With the use of such algorithms, a certain node spreads information probabilistically to its neighborhood. Evidently this is a rational approach since the neighborhood changes frequently and nodes are not necessarily in need of the generated contextual stream. IPAC mainly targets embedded devices such as OS-powered sensor motes, smartphones and PDAs. The platform relies on the OSGi framework (a popular middleware for embedded devices) for component deployment, management and execution. We discuss implementation issues focusing on the broad spectrum of IPAC services that were developed in order to facilitate applications. We elaborate on the networking stack that implements epidemical dissemination. We also discuss how such infrastructure has been used to realize applications related to crisis management and environmental protection. We present an adaptive flavor of the epidemical dissemination which expedites delivery by tuning the forwarding probability whenever an alarming situation is detected.