RPL Enhancement for a Parent Selection Mechanism and an Efficient Objective Function

In routing protocol (RPL), a child node exclusively makes the decision in selecting a parent based on the Rank value. In this paper, we make the parent selection mechanism, a mutual decision between the potential parent node and the child node, which significantly improves the network throughput under a heavy and highly dynamic load. To demonstrate the effectiveness of our parent selection mechanism, we used it to balance the load to avoid congestion by preventing the child node from using the congested parent node. The proposed parent selection mechanism is implemented as an add-on feature in RPL and hence is called enhanced RPL (EN-RPL). Furthermore, we introduce a new objective function for efficient routing (OF-ER) that is based on the newly defined composite efficient routing (CER) metric. CER metric takes important metrics, namely, the link quality, queue utilization, lifetime of node, delay, and number of bottleneck nodes, into account for optimal parent selection. The simulation results demonstrate that EN-RPL lowers the packet loss by up to 37% and reduces energy consumption by up to 46.5% compared with the standard RPL. The evaluation results of OF-ER outperform the state-of-the-art load balancing-based OF with respect to the network stability, reliability, and energy efficiency.