Energy harvesting effect on prolonging wireless low power lossy network lifespan

Abstract

Internet of Things (IoT) is a pillar technology for the next coming industrial revolution by enabling connections between deployed small devices wherever and whenever. However, these devices are often constrained in processor, memory, and energy. Usually known as sensor nodes, these devices are connected with each other to form a network of different nodes. As a matter of fact, routing the data in such environment is a challenge because of constrained sources of power. Therefore, Routing Protocol for Low-Power and Lossy Network (RPL) was formed by Internet Engineering Task Force (IETF) to develop an adapted routing solution for such networks, made up of large number of constrained nodes with limited processing power, memory, and energy. However, the overhead exchanged, to facilitate the routing process and maintain connectivity, drains these battery-operated nodes. This research examines a solar energy harvesting module to power such constrained network devices and quantifies the effect of using harvested energy on prolonging the network lifetime when RPL routing protocol is used. Simulation is conducted in three different scales (25 nodes, 50 nodes, 100 nodes) using Contiki Cooja simulator sporting Zolertia Z1 motes. Furthermore, the harvested energy was fed from an experimental power trace. All battery levels were set to 1% of their total capacity for all nodes in the network to expedite the process of observing the energy harvesting effect. The performance evaluation results showed that the network with no-energy harvesting operated for time duration of 4:08:04 time units (e.g., hour:minute:second) with a dramatic decrease in connection between nodes in the network. However, the same network, when using the harvested energy to back up the battery operation, lasted for 6:40:01 in time units with improved connectivity, a total extended network lifetime of 2:31:97-time units. Furthermore, for the RPL routing metrics, OF0 outperformed ETX in term of throughput, packet delivery ratio, energy consumption, and network connectivity.