International Journal of Engineering and Advanced Technology (IJEAT) ISSN: 2249 – 8958, Volume-8 Issue-6, August 2019 2122 Published By: Blue Eyes Intelligence Engineering & Sciences Publication Retrieval Number F8485088619/2019©BEIESP DOI: 10.35940/ijeat.F8485.088619 Energy Efficient Hierarchical Routing Protocols for IoT Neha Rani, Pardeep Kumar Abstract—IoT (Internet of Thing) is a wireless network in which smart objects communicate and interact with each other through internet, it also remotely control and monitor the objects within network. In IoT, data is sensed, gathered, processed and stored from real world environment. In this procedure a large amount of energy is consumed. Energy efficiency is the main concern for IoT. In this paper introduction to IoT its layered architecture, applications and various cluster based routing protocols has been introduced. The cluster based routing protocols used different schemes to make the nodes energy efficient. The major focus of this paper is on the LEACH, SEP, HEED and TEEN protocols. Index Terms—IoT (Internet of Things), Sensor, Cluster Head, Routing Protocols I. INTRODUCTION The Internet of Things is an upcoming research area in recent days. Earlier the IoT was connecting PCs only but nowadays IoT has been changed from ”internet of people” to ”internet of things”. Kelvin Ashton coined the IoT in 1999 and said ”we need to empower computers with their own medium of information”. RFID and sensors technology allow computers to detect, recognize and know the world without the control of human intervention. The innovation can be created by sharing the data among smart things. The concept of IoT is the existence of smart objects like laptops, tablets, smart phones equipped with sensors and actuator. These objects are smartly communicating with each other. It is expected that Internet of Things will encompass 26 billon units connected by 2020. Billions of devices are anticipated to connect to the internet in coming years that will demand a well defined mechanism where the objects work automatically.[1] IoT is the interconnection among objects. In IoT data is transferred from one device to other device through internet.Routing is the selection of best path from source to destination. Data can be transferred from machine to machine (m2m), machine to human and human to machine. The basic concept of routing in IoT is that the sensed data is transferred in a continuous way from one node to another node. Large amount of energy is required for data transfer in IoT networks. This paper presents the different cluster based routing protocols to make the nodes energy efficient. Routing protocols are classified into three types (1) Network Organization (2) Route Discovery and (3) Protocol Operation. Network organization is divided into three categories viz; flat based routing, hierarchical routing and location based routing. In this paper the focus is on hierarchical routing. Revised Manuscript Received on August 25, 2019. Neha Rani, Department of Computer Science and Applications, Kuruk-shetra University Kurukshetra, India. nehasaini614@gmail.com Dr. Pardeep Kumar, Department of Computer Science and Applications, Kurukshetra University, Kurukshetra, India. mittalkuk@gmail.com In this routing highest energy level nodes are used for the transmission and remaining nodes are used for sensing the data. This is also called cluster based routing because nodes are collected within different clusters for the fast delivery of data. Hierarchical routing used the protocols like LEACH, HEED, TEEN, SEP etc. [2] II. ARCHITECTURE OF IOT  Perception Layer: This layer is the lowest layer of IoT architecture. It collects data from environment such as (WSN, heterogeneous devices and real world object) of sensor type and transmits them in an automated setup.  Network Layer: The function of this layer is to transmit the data between lower and upper layer. It accumulates data in digital format from the perception layer, arrange the framework and then transmit it to the application layer via Bluetooth and WiFi. Fig. 1. Layered Architecture of IoT[3]  Service Layer: This layer combine and store the data from network layer and send it to the upper layer. It provides different types of services like management services, data analysis and decision making.  Application Layer: This is the top layer of IoT ar- chitecture. This layer provides the specific services to industries. These services are environment monitoring, smart healthcare, smart transportation, smart agriculture etc. [3] III. APPLICATIONS OF IOT  Smart Cities: IoT make the peoples life easy to provide the facilities in their city. These facilities are: remove the traffic congestion on the road, improve the infrastructure, provide the internet facilities for accessing the database of railways and airports etc.  Smart Home: By using IoT technology we can smartly operate our home devices like smart lights, automatically adjustment of room temperature, security of homes, water supply, power