Trickle-D: High Fairness and Low Transmission Load With Dynamic Redundancy

Embedded devices of the Internet of Things form the so-called low-power and lossy networks. In these networks, nodes are constrained in terms of energy, memory, and processing. Links are lossy and exhibit a transient behavior. From the point of view of energy expenditure, governing control overhead emission is crucial and is the role of the Trickle algorithm. We address Trickle's fairness problem to evenly distribute the transmission load across the network, while keeping the total message count low. First, we analytically analyze two underlying causes of unfairness in Trickle networks: 1) desynchronization among nodes and 2) nonuniform topologies. Based on our analysis, we propose a first algorithm whose performance and parameters we study in an emulated environment. From this feedback, we design a second algorithm Trickle-D that adapts the redundancy parameter to achieve high fairness while keeping the transmission load low. We validate Trickle-D in real-life conditions using a large scale experimental testbed. Trickle-D requires minimal changes to Trickle, zero user input, emits 17.7% less messages than state-of-the-art and 37.2% less messages than state-of-practice, while guaranteeing high fairness across the network.