International audienceIn this paper we develop an explicit formula of outage probability in a distributed wireless sensor network (WSN), assuming the MAC layer protocol being a slotted-ALOHA. And adopting a Markovian approach, we develop a model that analyses the performance of the slotted-ALOHA in order to improve these performances, in particular, by adding a preliminary stage of channel reservation, we show that this modification is important to have a high performance distributed wireless sensor network
