An Improved RPL Algorithm for Low-Power and Lossy Networks

The routing protocol for low-power and lossy networks(RPL), standardized by Internet Engineering Task Force(IETF), is mainly designed to use for Low-power and Lossy Networks(LLNs). To solve the problems of several important routing metrics are not evaluated, the optimal path may contain long single hop links, lack of scientific multi-routing metrics evaluation method and mechanism to balance the parent child number(especially the parent with one hop away from root), this paper proposes an improved RPL algorithm for LLN(I-RPL). First of all, we propose the evaluated routing metrics: child number of parent, candidate parent number, hop count, ETX and energy consumption index. Meanwhile, we improve the path ETX calculation method to avoid selecting optimal path containing long single hop links. Then we design a novel lexical method to synthetically evaluate candidate parents. Meanwhile, based on the evaluation results of candidate parents, we design a novel objective function and a new calculation node rank method which can also be used for selecting the optimal path. Finally, evaluation results show that I-RPL outperforms ETXOF and several other improvements in terms of packet delivery ratio, latency, etc.