Exploiting multiple parents in RPL to improve both the network lifetime and its stability

The devices composing Wireless Sensor Networks (WSN) are very limited in terms of memory, processing power and battery. RPL has emerged as the de facto routing standard in low-power and lossy networks. While most of the proposals focus on minimizing the global energy consumption, we aim here at designing an energy-balancing routing protocol: each node should efficiently consume the same quantity of energy to improve the network lifetime. To this end, we exploit an Expected Lifetime metric, denoting the residual time of the nodes (time until the node will run out of energy). We propose mechanisms to detect the energy-bottleneck nodes and to spread the traffic load uniformly among them. While RPL constructs a Destination-Oriented Directed Acyclic Graph (DODAG) structure, it only implements single path. We propose here to exploit its natural multipath structure. This multipath approach helps reducing the number of DODAG reconstructions that leads to instabilities and convergence problems. Simulations highlight we improve both the routing reliability and the network lifetime.