Abstract. We consider wireless ad-hoc networks and implement failure detections mechanisms. These failure detectors provide elementary information for high level distributed algorithms such as consensus, election or agreement. The aim is to guarantee a quality of service for these mechanisms. Stochastic models for tuning failure detectors are proposed based on frequency analysis and contention modelling. Tuning methods are suggested for setting time-out delays. The theoretical results were validated experimentally on a wireless platform, based on a statistical analysis of the measurements.