Heterogeneity consideration in wireless sensor networks routing algorithms: a review

Wireless sensor networks (WSNs) are resource-constrained networks with limited battery power, computation abilities and communication capabilities at the sensor node level. A long-standing need in the area is to reduce energy consumption of the WSN nodes and to extend the network lifetime, along with improving the network reliability and the network quality. Energy-efficient routing protocols can improve the WSN performance, and the algorithms have been explored widely by the researchers. In the majority of the work, sensor nodes have been considered homogeneous in their configuration and capabilities. However, in practical scenarios and with the advent of an era of connected devices, called Internet of Things, consideration of node heterogeneity in WSN has become inevitable. Nodes' heterogeneity can be exploited constructively in WSN routing algorithms. In the literature, many different heterogeneous WSN scenarios (e.g., energy, computation, link heterogeneities) have been considered and the routing algorithms have been proposed for performance improvement in such scenarios. This paper focuses on the routing concepts for diverse heterogeneous WSNs scenarios and covers the state of the art in the area. The clustering-based approaches for routing decisions are extensively covered under different heterogeneous WSN scenarios. Along with presenting a comprehensive review of the routing algorithms under different varieties of heterogeneous WSNs, the paper also discusses the effects and interdependencies of different heterogeneities in routing decisions and unveils new research directions in the area.