Machiavel: Accessing the medium in mobile and dense WSN

Wireless sensor networks operate in constrained environments. In addition to the limitations in terms of energy, memory and computation, the use of mobile sensors has recently been contemplated. However, only a few medium access control protocols consider the dynamic of such scenarios. In this paper, we present potential problems that could arise with nowadays protocols operating in mobile environments. We particularly focus on the synchronization issues between fixed and mobile sensors, as well as congestion in dense networks. For that purpose, we introduce Machiavel, a new method to access the medium. Machiavel allows mobile sensors to capture the channel even in networks with high contention, while guaranteeing the synchronization with their peers. An evaluation by simulation demonstrates the benefits of our contribution compared to the B-MAC protocol.