Enhanced Objective Function ETX Metric in Routing Protocol for Low-Power and Lossy Networks (RPL)

Abstract

An Internet of Things (IoT) is a technique capable of real-time object connections on the Internet and accessing them anywhere at any time. The low-power wireless network is the primary component for Internet of Things applications. In this scenario, the major processes of the wireless sensor network (WSN) applications are considered routing, deploying low-power nodes, load balancing, and controlling remotely. The Internet Engineering Task Force (IETF) is systematized to enable communication over Low-Power and Lossy Networks (LLNs) using Internet Protocol Version 6 (IPv6) routing. The Routing Over Low-power and Lossy Networks (ROLL) working group has determined a new routing protocol for LLNs named Routing Protocol for Low-Power and Lossy Networks (RPL). Moreover, two Objective Functions (OF) are designed for implementing the routing technique that applies the metrics. In the network routing process, hop count is a core metric in Objective Function Zero (OF0), and expected transmission count (ETX) is a metric in Minimum Rank Hysteresis Objective Function (MRHOF). However, the network becomes high-density, and nodes are increased. Adapting the existing objective function single metric generates long hops and bottlenecks affecting network performance. To solve the stated problem, the objective function requires optimized enhanced metrics. This paper aims to provide an optimization path selection in RPL by implementing a new routing objective function metric. It is called Variance Expected Transmission Count (VETX), in which the optimized best route is computed by the method of modified variance calculated in ETX values. This implementation is simulated using the Cooja simulator, and the obtained result of the enhanced ETX metric (VETX) ensures an average of 2.6% outperformance in OF0 and MRHOF in the subjects of packet delivery ratio, latency, energy consumption, overhead, and goodput.