A hybrid mode of operation for RPL networks

Nowadays, more and more devices getting smart abilities by connecting to the Internet. These devices and the networks these form are generally called Internet of Things. Internet of Things is a concept that considers variety of objects that are able to interact with each other through wireless medium. This enables the things to corporate and achieve their goals without any human intervention. According to the estimations, there will be 50 billion devices connected to Internet by 2020. Internet of Things networks are classified under Low-Power and Lossy Networks because of their constrained nature. Interconnection of these networks is done by using IPv6 over Low-Power Wireless Personal Area Networks protocol stack on top of IEEE 802.15.4 physical layer protocol. IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL) is the IETF proposed routing protocol for constrained networks. It enables Internet of Things devices to interact with each other and the rest of the Internet. RPL constructs a tree-like topological structure rooted at a border router. Construction of the network is initiated by this root node. Each node participates to the network by selecting a parent among their neighbours. RPL enables upward routing towards root node by using the default route to parent nodes. For downward routing, it offers four different modes of operation to fullfil requirements of different applications. However, a RPL instance may run under one of these modes of operation. This thesis investigates problems caused by RPL's mode of operation mechanism and offers a solution by defining Hybrid Mode of Operation. The proposed method solves conectivity problems and increases network performance in terms of hop count and network load balance. Moreover, the proposed method provides compatibility with standard RPL.