Heterogeneous Routing Protocols in Wireless Sensor Network: A Survey

---------------------------------------------------------------------***--------------------------------------------------------------------Abstract: In a heterogeneous wireless sensor network, higher energy nodes can become cluster heads more times than the nodes with low energies. This means that creation of cluster heads and assigning tasks to them can greatly contribute to energy efficiency which results in increase in stability and network lifetime. Recent years have seen a tremendous growth in wireless sensor networks due to reduction in manufacturing costs and improvement in hardware manufacturing. Wireless Sensor Networks are now widely used in various fields like industrial monitoring, habitat monitoring, environment monitoring, surveillance etc. As these networks are energy limited, researchers are working on these networks in making them more energy efficient. A lot of energy efficient heterogeneous routing protocols have been proposed in recent years to increase the stability and overall lifetime of the network and this paper provides a review on these protocols.