Now a days wireless sensors are attracting strong interest for different monitoring and controlling applications as they are integrated with the function of sensing, processing and wireless communication. The wireless sensor networks have been deployed for agricultural, industrial, remote monitoring and traffic management purposes. As energy shortage is a worldwide problem so that more attention has been placed on incorporating energy harvesting devices in wireless sensor networks. The main purpose of this paper is to focus on the systematic study of the design principles of wireless sensor networks and to provide technical approaches to address three key challenges in designing of reliable and endurable wireless sensor networks. The key challenges are namely communication reliability, operation with significantly low and effective power sources and multi-tier network architecture. © 2017 IEEE.