Wireless sensor networks (WSNs) consists of large number of multifunctional sensor nodes. Sensor nodes are battery powered and deployed in harsh environments so it is not always possible to recharge or replace the batteries. Sensor node basically sense data, collects data from other nodes then process that data and then transmit this collected data to the base station. It is proved that node require much power or energy to transmit data rather than sensing thus routing protocols developed for wireless sensor networks must be energy efficient so that the network lifetime can be prolonged. Routing protocols developed for other adhoc networks cannot be applied directly in WSN because of the energy constraint of the sensor nodes. Sensor networks are used in many applications like environment monitoring, health, industrial control units, military applications and in the various computing environments. Since the entire sensor nodes are battery powered devices, energy consumption of nodes during transmission or reception of packets affects the life-time of the entire network. In this paper, a survey on various energy efficient routing protocols based on their architecture has been done indicating their merits and demerits.

Keywords: wireless sensor network, Design challenges, Routing protocol, Data centric, Hierarchical, Location based.