Do We Really Need a Priori Link Quality Estimation?

Traditionally, link quality estimation (LQE) has been viewed as an a priori step in sensor network routing protocols because it filters out unreliable links before data transmission. Recent results, however, show that protocols can perform well without a priori LQE. Because getting rid of LQE seems rather counter-intuitive, the aim of this work is to look deeper into the behavior of LQE-free protocols. Our results, based on one of the state-of-the-art LQE-free protocols, show two interesting insights. First, LQE-free protocols manage to choose links that are slightly better than the ones obtained with a priori LQE methods. Second, in traditional protocols, the effort needed to identify good links accounts, on average, for roughly half of the energy consumption of nodes, depending on the nodes' active period and on the inter-packet interval. By eliminating this overhead, LQE-free protocols can save a significant amount of energy compared to standard approaches.