Energy-efficient data collection in WSN: A sink-oriented dynamic backbone

In wireless sensor networks, energy efficiency is generally achieved by turning off some capabilities from a subset of deployed sensors. The set of active nodes must therefore meet the application requirements (e.g. area coverage, data redundancy) while remaining fully connected to allow further data collection. Here, we focus on the case of a nomad sink entering the network and gathering every monitoring data. At the routing layer, minimizing the number of nodes acting as relays requires to construct a maximum leaf spanning tree (MLST). However, optimizing convergecast communications consists in minimizing the hop distance between the sink and all others nodes, leading so to a shortest path tree rooted at the sink. In this paper, we propose a distributed routing protocol that aims at constructing an energy efficient backbone being convergecast efficient at the same time. Our proposal introduces a tradeoff parameter to adjust the compromise “number of relays / routing efficiency” and then constructs a hybrid routing structure based on the combination of variants of the Wu-Li algorithm and a gradient-based routing protocol. For all topologies we simulated, and when tuned for energy saving, our approach outperforms a 2-approximation for constructing a MLST. Furthermore, when tuned for convergecast routing, simulation results show that our solution constructs a routing optimal backbone that involves a small fraction of relays.