Saving power while ensuring acceptable service levels is a major concern in wireless sensor networks, since nodes are usually deployed and not replaced in case of breakdown. Several efforts have recently led to the standardization of a routing protocol for low power and lossy network. The standard provides various metrics, which can be used to guide the routing. Most protocol implementations use expected transmission count as the routing metric, thus focus on the link reliability. To our knowledge, there is no protocol implementation that uses the nodes remaining energy for next hop selection. This document discusses about the usage of the latter as the routing metric for RPL, the new standard for routing for Low power and Lossy Network (LLN). We design an objective function for that metric and compared experiments result with the most popular expected transmission count scheme.
