The effect of node selfishness on the performance of WSN cluster-based routing algorithms

In Wireless Sensor Networks (WSNs), energy efficiency is among the most important factors since the lifetime of an unattended node is limited by its battery lifetime. In infrastructure-less WSNs, in order to use their resources efficiently, nodes can be organized hierarchically. In this case, long range communication is entrusted to a subset of nodes, the Cluster Heads (CHs): each CH acts as a gateway between the local nodes in its cluster and the other CHs in the network. When in this role, a node must stand a heavier traffic and consume more resources: fairness dictates that the role has to be taken in turn by each node in an area that fits the task. However, a selfish node may adopt several strategies to save its energy: it can make itself unavailable for the role of CH, or, when in that role, it can avoid relaying packets. In this work, we study the impact of selfish nodes on the performance of the cluster based algorithm LEACH. By taking into consideration several Quality of Service metrics, we quantify the extent of performance degradation as a function of the percentage of selfish nodes. We show that, when the percentage of selfish nodes is 75%, only 37% of packets reach the base station, network lifetime reduces to 40% of rounds and packet retransmission attempts is close to 63%.