An EAR Routing Protocol for Wireless Sensor Networks

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ATRI, JNTUH. Hyderabad,A.P,INDIA e-mail:[email protected] Abstract--Fixed-power wireless sensor networks are prevalent and cost-effective. However ...

2011 International Conference on Digital Convergence (ICDC 2011)

An EAR Routing Protocol for Wireless Sensor Networks (WSNs) Siva Ram Chinthala

S Naga Kishore Bhavanam

M.Tech.(E.S), Dept. of E.C.E. ATRI, JNTUH Hyderabad, A.P,INDIA e-mail:[email protected]

M.Tech.(VLSI-SD), Dept. of E.C.E ATRI, JNTUH Hyderabad, A.P,INDIA e-mail: [email protected]

Prof. S Srinivasa Rao, (Ph.D) H.O.D, Dept. of E.C.E ATRI, JNTUH Hyderabad,A.P,INDIA e-mail:[email protected] Abstract--Fixed-power wireless sensor networks are prevalent and cost-effective. However, they face mote failures, RF interference from environmental noise and energy constraints. Routing protocols for such networks must overcome these problems to achieve reliability, energy efficiency and scalability in message delivery. Achievement of these requirements, however, poses conflicting demands. In this paper, we propose an efficient and reliable routing protocol (EAR) that achieves reliable and scalable performance with minimal compromise of energy efficiency. The routing design of EAR is based on four parameters – expected path length and a weighted combination of distance traversed, energy levels and link transmission success history, dynamically determine and maintain the best route. Simulation experiments of EAR with existing protocols demonstrate that a design based on a combination of routing demonstrate that a design based on a combination of routing parameters exhibits collectively better performance than based on just hop-count and energy of those using flooding.

Fig1. Conventional Cellular System

Wireless sensor networks (WSNs) are the networks of tiny and low power devices. These devices are called as sensor nodes, because the major task of theses sensor networks is to sense the data from environment. Hence, sensor nodes can be used for monitoring purpose. After sensing the data from the environment, sensor nodes perform some computations on the data in order to extract some useful information. Then this information is send to the sink, a powerful node which collects the data from the sensor nodes and forwards it to the control centre through satellite or internet. Wireless sensor networks (WSNs) open up new application areas such tactical surveillance, intelligent environmental and structural monitoring and target tracking A typical WSN is shown In Fig2.[3] .

Index Terms: EAR, hop count, reliable routing, routing protocol, wireless sensor network, Packet Delivery Ratio, NS-2.34.



If we want establish the communication between two mobile stations, there is a long procedure which is illustrated in Fig1. This type of communication requires sophisticated architecture which leads to so many complications such as cost, maintenance and etc. So we are adapting routing protocol to establish communication in this environment[2].

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2011 IEEE


2011 International Conference on Digital Convergence (ICDC 2011)

Several routing protocols in fixed-power, multi-hop WSNs use shortest-path routing. Since operation is often over long unattended periods, the protocol must be energy efficient. The environment is also unpredictable and often disrupts operation. As such, routing protocols must ensure that the WSN can reconfigure, be energy efficient and resilient to failures. These non-trivial requirements pose conflicting demands on protocol design. With these issues in mind we propose an efficient and reliable routing protocol (EAR) that route messages to one or more hubs for dataaggregation applications. EAR takes into account the expected path length and a weighted combination of distance traversed, energy level and past performance of an RF link for its routing decisions control overheads in EAR are low.[1]

Fig2.Wireless Sensor networks

A wireless sensor network (WSN) is a wireless network consisting of distributed self-organized autonomous devices using sensors to cooperatively monitor physical or environmental conditions, such as vibration, motion, temperature, sound etc.



Routing based on hop count and node energy levels dose not account for dynamically varying RF-Link conditions in operating environment. An optimal route need not be the shortest and a more stable RF-Link may be more efficient and reliable the duplicate packets that are routed to enhance delivery success incurs additional and energy consumption and increased latency. The performance of the routing protocol also has to scale with network size.[1] The challenge then is to develop a routing protocol that meet these conflicting requirements while minimizing compromise.

A WSN node mainly consists of four main parts: 1-Processing unit, 2- Sensor 3- Transceiver 4- Energy Source Unit Depending on usage purpose there may be additional components such as localization unit, energy producer, position changer etc. In the Fig3, general architecture of WSN node and a real example is represented [6]



The procedural design of EAR may be divided into three phases:setup, route selection, and data dissemination. These are detailed in the following sections. A. Setup Phase: When a hub is powered on, it broadcasts an Advertisement (ADV) packet indicating that it wants to receive RPT packets. When a neighboring node around the hub receives this ADV packet, it will store the route to the hub in its routing table. Nodes do not propagate the ADV packet received. A node may store more than one route to the hub. A route in the routing table is indexed using the next hop node’s ID – that is the ID of the neighboring node. A node keeps only one route entry for a neighbor that has route to the hub even though that neighbor could have multiple routes to the hub.[1] B. Route Selection Phase: Ideally, the best route is the shortest as it incurs the lowest latency and consumes the least energy. In an actual environment, the performance of an RF link varies with physical distance and terrain between nodes and should be accounted for in routing decisions. In EAR, shortest routes are initially admitted into the routing table based on hopcount. As RPT packets flow through these links, less desirable ones will start to exhibit high packet loss rate and

Fig3: WSN Node architecture and a real example.


2011 International Conference on Digital Convergence (ICDC 2011)

are eventually blacklisted and omitted from the routing table. Links that are omitted from the routing table may be readmitted again only after a period of time. Some RF links are affected by temporary external disruption and should be given the chance to be re-admitted. This allow for adaptiveness. The mechanism uses a sliding window that keeps track of the last N attempts, and then it will be blacklisted and omitted from the table.[1]

Fig5 Piggy Backing on RTS/CTS packet



Fig4 Illustration of forwarding based on Link Score Metric

A metric, Link Score=(PE*WE + PT *WT), where PE – energy level of the next of the hop node (0.0 to 100.0), WE – assigned weight for PE(0.0 to 1.0), PT – transmission success rate(0.0 to 1.0) .Weights, WE and WT, may be determined empirically but their sum must equal..Link Score is used when there are two links of different routes with the same hub distance competing to be admitted to the routine table. This is illustrated in Fig 4. When there is more than one entry with the same Link Score, the entry with the longest length is chosen to be replaced. If there is a tie in route length, then the route with the higher Link Score is admitted[1].

We Simulated the network for a 10 nodes in 10 minutes in a radio propagation model. Ns-2.34 version simulator was used to emulate a WSN.[4] and used on Red Hat Linux Operating System[5] A) Set up phase: The bellow how the nodes are established in wireless environment. It is nothing but set up phase in our rouiting protocol.

C. Data Dissemination: Sensor nodes generate RPT packets at periodic intervals or sleep, waiting for some event to happen. An RPT packet contains information of interest to network users and has two fields in its header: ExpPathLen and NumHopTraversed. The first field is the expected number of hops the packets will have to traverse before it reaches the hub. It is defined as ExpPathLen = NH x a, where 0.0 < a< 1.0, NH is the number of hops from this node to the hub for the route selected. The route selected need not be the shortest but ExpPathLen is bounded by the network diameter, a mini number of hops to reach the hub is at least 1 [1].

Fig6 Set up Phase

B) Route Selection Phase: After set up phase the next step is Route Selection Phase. Here te routing is to be done based on a metric which is a Linkscore. Which is illustrated in fig.7(i) and 7(ii)

D. Route Update: Sensor nodes continually update “best” routes in the routing table. Instead of explicit control packets. EAR uses the handshaking mechanism at the MAC layer. Route information is piggybacked onto both RTS and CTS packets. Fig 4 illustrates this scenario. Hence utilizing RTS and CTS handshaking instead of separate DATA-ACK would result in more current route information for a node.[1]


2011 International Conference on Digital Convergence (ICDC 2011)

Fig7(i) Route Selection Phase

Fig. 8 Packet Delivery Ratio Vs No. of Nodes



In this project we proposed a viable routing protocol, EAR, for data aggregation in fixed-power WSNs. Routes are managed based on expected path length and a weighted combination of distance traveled, energy level and RF link performance history. VI.

Fig7(ii) Route Selection Phase

C) Final Route: After successful routing the nodes are formed like bellow fig8.


We would like to thank the Faculty of Aurora’s Technological and Research Institute for their support. We acknowledge Mrs. Humaira and Mrs.Y, Naga Supraja help in the development and testing of our EAR routing Protocol. REFERENCES [1] “ Performance Evaluation of Efficient and Reliable Routing Protocols for Fixed-Power Sensor Networks”, IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, VOL. 8, NO. 5, MAY 2009.

Fig8 Final Route

Here the data dissemination and route update will done during route selection phase hence it is not possible to show in separate window. Simulation results of Packet delivery ratio Vs No. of nodes:


Wireless Communications Principles and Practice 2nd edition 1998 by Theodore S. Rappaport


“Progressive Energy-Awrare Routing in Wireless Sensor Networks”, Khalid, Z., Khan, N.M., Ahmed, G. Electrical Engineering, 2009. ICEE '09. The Third International Conference on 9-11 April 2009

[4] [5] [6]

www. www. red- hat Haroun, I.,Lambadaris, I., Hafez, R. (September, 2005). Building Wireless Sensor Networks. March 26, 2007 from the World Wide Web:

About Authors

Here we can say that the packet received rate is far better than packet lost.

Siva Ram Chinthala is an M.Tech Post-Graduate of Embedded Systems from Aurora’s Technological and Research Institute (ATRI), Department of ECE, JNTUH. He obtained his B.Tech from RGMCET Nandyal. His interesting fields are Communications, Embedded Sysems, and Signal Processing.


2011 International Conference on Digital Convergence (ICDC 2011)

S.Srinivasa Rao , working as Professor in the Department of ECE, Aurora’s Technological & Research Institute, Hyderabad. Has more than 17 years of teaching experience. He got his B.Tech from Madras Institute of Technology, Madras, M.Tech from JNTU , Hyderabad and pursuing PhD in JNTU, Hyderabad.

S Nagakishore Bhavanam is an M.Tech PostGraduate of VLSI-SD from Aurora’s Technological & Research Institute (ATRI), Department of ECE, JNTUH. He obtained his B.Tech from S.V.V.S.N Engineering college ONGOLE. His interesting Fields are Low Power VLSI and Communications.


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