Performance of RPL Objective Functions Using FIT IoT Lab

Abstract

AbstractThe Internet of Things is a system, which connects many heterogeneous devices and it finds application in several areas. The network used in IoT is Low Power and Lossy Networks (LLN) because the devices used in IoT are power constrained. LLN uses Routing Protocol for Low Power and Lossy Networks (RPL) as its routing protocol and it is considered as an IETF standardized protocol for LLN. RPL constructs Destination Oriented Directed Acyclic Graph (DODAG) to select the appropriate path to the destination. In RPL, the DODAG can be constructed based on the objective function. Thus, the selection of the best objective function plays a major role in RPL. The main metric for selection of objective function is the power, as our focus is on the design of power efficient IoT. The most widely used objective functions in RPL are OF0 and MRHOF. The metric used by objective function OF0 is hop count and MRHOF uses expected transmission count metric. In the existing research, the superiority of these two objective functions is established using only simulation studies but not based on the real testbed experiment. Hence, it is necessary to conduct the experiment in the real testbed to assess the suitable objective function. In this paper, experiments are conducted in the FIT IoT Lab to select the best objective function with respect to the power parameter. From the result, it is identified that both OF0 and MRHOF perform equally and in some cases, it is observed that MRHOF is more power efficient than OF0. The objective functions are also evaluated for single and multi sink scenarios. It is identified through the experiments that the increase in the number of sink nodes does not affect the power consumption.