Energy balancing RPL-based routing for Internet of Things

RPL (IPv6 Routing Protocol for Low-Power and Lossy Networks) is a standard routing protocol for low-power low-cost and resource constrained networks. To deal with the diversity in link qualities in these networks, the Minimum Rank with Hysteresis Objective Function (MRHOF, RFC 6719) is standardized as the de facto Objective Function (OF) for RPL. MRHOF helps a mote to select a path to forward traffic with the minimum cost among available paths. The Expected Transmission Count (ETX) defined in RFC 6551 is the most widely used MRHOF routing metric. ETX helps to achieve good Packet Delivery Ratio (PDR) and low latency since motes choose to relay their information along the path with the least number of retransmissions. However, since ETX does not consider the energy level of the motes, it does not balance the energy consumption between motes. In this paper, we develop other routing metrics by taking into consideration the energy consumption of motes as routing metric. We develop a Radio Duty Cycle (RDC) based method to estimate mote energy consumption. We also look into diverse combinations of ETX and energy consumption as routing metrics. The proposed methods achieve better energy balance while keeping good energy efficiency and packet delivery ratios.