The RPL accounts for node attributes and link quality measurements in Objective Functions (OFs) to construct the Destination Oriented Directed Acyclic Graph (DODAG) towards root devices. In default, the RPL does not include composite routing metrics, so it is not suitable for different network scenarios. The network congestion and load imbalance in RPL make it invaluable in IoT smart applications. It is paramount to design a better OF model for RPL without affecting the network resources.
   Recently, Sigma-ETX has been used in RPL to address a problem in the OF with ETX. It is difficult to choose the path with a minimum hop count and minimum ETX under a dense network scenario. It tends to be a bottleneck in the network and create unwanted congestion. To avoid this, it is essential to consider the sum of all the ETX in the path along with the standard deviation of ETX between each node. It offers a better trade-off between the minimum hop count and the ETX.