Wireless Sensor Network, 2012, 4, 65-75 http://dx.doi.org/10.4236/wsn.2012.43010 Published Online March 2012 (http://www.SciRP.org/journal/wsn) An Integrative Comparison of Energy Efficient Routing Protocols in Wireless Sensor Network Ali Norouzi 1 , Abdul Halim Zaim 2 1 Department of Computer Engineering, Istanbul University (Avcilar), Istanbul, Turkey 2 Department of Computer Engineering, Istanbul Commerce University (Eminonu), Istanbul, Turkey Email: norouzi@cscrs.itu.edu.tr, azaim@iticu.edu.tr Received December 8, 2011; revised January 11, 2012; accepted January 30, 2012 ABSTRACT Many advances have been made in sensor technologies which are as varied as the applications; and many more are in progress. It has been reasonable to design and develop small size sensor nodes of low cost and low power. In this work, we have explored some energy-efficient routing protocols (LEACH, Directed Diffusion, Gossiping and EESR) and their expansions (enhancements), and furthermore, their tactics specific to wireless sensor network, such as data aggregation and in-network processing, clustering, different node role assignment, and data-centric methods. After that we have compared these explored routing protocols based on different metrics that affect the specific application requirements and WSN in general. Keywords: Wireless Sensor Network; Routing Protocol; Energy Consumption; LEACH; Directed Diffusion; Gossiping; EESR 1. Introduction Wireless Sensor Networks consist of tiny sensor nodes that, in turn, consist of sensors (temperature, light, humi- dity, radiation, and more), microprocessor, memory, trans- ceiver, and power supply. In order to realise the existing and potential applications for WSNs, advanced and ex- tremely efficient communication protocols are required. WSNs are application-specific, so the design requirements of WSNs change according to the application. Hence, rout- ing protocols’ requirements are changed from one appli- cation to another. For instance, the requirements of a rout- ing protocol designed for environmental applications is different from that designed for military or health appli- cations in many aspects. As a result, routing protocols’ requirements are as diverse as applications’. Some of the- se are: Scalability, Latency, Throughput, Recourse Awa- reness, Data Aggregation, Optimal Route, over-head, and other metrics. Some applications need some of these me- trics to be provided and other applications need others to be provided. However, routing protocols of all Wireless Sensor networks, regardless of the application, must try to maximise the network life time and minimise the en- ergy consumption of the overall network. For these rea- sons, the energy consumption parameter has higher pri- ority than other factors. 2. Routing Protocols in Wireless Sensor Network Due to these differences, many new algorithms have been proposed for the routing problem in WSNs, taking into account the inherent specification of WSNs along with the application and architecture requirements. 2.1. LEACH Protocol Low-Energy Adaptive Clustering Hierarchy (LEACH) is a clustering based protocol that uses a randomised rota- tion of local cluster base stations. The nodes in LEACH are divided into clusters and each cluster consists of members called Cluster Members and a coordinator node called the Cluster Head, CH. The cluster heads are not selected in the static manner that leads to quick die of sensor nodes in the network. However, the randomised protocol has been used in order to balance the energy consumption among the nodes by distributing the CH’s role to the other nodes in the network. Furthermore, LEACH uses Time Division Multiple Access (TDMA) protocol in order to regulate the channel access within a cluster [1]. It is the responsibility of the CHs to assign TDMA slots to the cluster members. The peer to peer communi- cation between the CH and a member is done just during the time slot that assigned to that member, and the other members will be in their sleep state. Hence, it decreases the energy dissipation; see Figure 1. Moreover, LEACH uses the TDMA communication protocol to decrease the interference between the clusters. LEACH has been produced to overcome the disad- vantages of the Flat-Architecture Protocols that consume Copyright © 2012 SciRes. WSN