Resource Aware Hierarchical Routing in Heterogeneous Wireless IoT Networks

Routing algorithm consumes the resources of the network nodes. Different routing algorithms require different amount of the resources. Nodes at different positions of the network topology require different amount of the resources. Routing algorithm must adapt to both available resources and required resources of the nodes. The IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL) considers memory and defines four modes of operation (MOPs). However, RPL allows only one MOP for all routers in a network. This paper presents a resource aware hierarchical RPL (H-RPL) to realize the mixed MOPs and the resource adaptation in heterogeneous wireless IoT networks. Taking routing preferences of the nodes into account, H-RPL also applies heterogeneous routing metrics and objective functions in hierarchical network topology construction. A new MOP is introduced to indicate the critical resource condition of the node. The required routing memory and the expected routing lifetime are proposed to determine the MOP of the node. The MOP downgrade and the MOP upgrade are introduced to address traffic congestion caused by the isolated higher resource node and to exploit the renewed resources and the resource requirement relaxation, respectively. The queue utilization based data transmission distributes data packets for load balance and network performance improvement. Simulation results show that H-RPL can improve upward data packet delivery rate by 7%, downward data packet delivery rate by 25% and extend network lifetime by 78%.