A Study of Routing Protocols for Energy Efficiency in Wireless Sensor Networks with Mobile Nodes

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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 3, Issue 4, April 2013)

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A Study of Routing Protocols for Energy Efficiency in Wireless

Sensor Networks with Mobile Nodes

Fahim Hasan Khan

1

, Md. Nazrul Islam Mondal

2 1

Lecturer, Dept of CSE, Military Institute of Science and Technology, Dhaka, Bangladesh 2Assistant Professor, Dept of CSE, Rajshahi University of Engineering & Technology, Bangladesh

Abstract—In Wireless Sensor Networks numerous sensor nodes are distributed over a diverse area to form the networks and doubtlessly the energy resources limit their overall operation. As it is difficult to recharging or replacing the battery of each node, so the energy efficiency of the system is one of the critical issues in designing Wireless Sensor Networks. In this paper, we considered the concept of Topology Control as a layer between MAC layer and routing layer, which has some very important aspects to reduce the energy consumption of Wireless Sensor Networks. In this research study, our main aim was to analyse the performances of AODV, DSDV and DSR routing protocols by simulation and determine the best performing routing protocol based on energy efficiency while considering the idea of Topology Control layer. This paper presents the comparative study of the performance of these three routing protocols on the basis of energy consumption for Wireless Sensor Networks with mobile nodes.

KeywordsWireless Sensor Networks, Topology Control, routing protocols, energy efficient routing.

I. INTRODUCTION

Wireless Sensor Networks (WSNs) can be described as wireless networks consisting of spatially dispersed autonomous devices using sensors to cooperatively monitor physical or environmental conditions like temperature, sound, vibration, pressure, motion, pollutants etc. at different locations. The devices used in Wireless Sensor Network are called smart sensors, sensor nodes or ‗motes‘. Most of the cases this smart sensor has limited power, limited memory and processing power, one or more sensors and a radio transceiver. So the main challenge here is to use limited power and resource to design a durable and effective sensor network. The magnitude of a single sensor node can vary from shoebox-sized nodes down to devices the size of grain of dust, where further research is going on to create sensor nodes of genuine microscopic dimensions. As well, the cost of sensor nodes varies, ranging from hundreds of dollars to a few cents, depending on the size of the sensor network and the complexity required of individual sensor nodes. Size and cost constraints on sensor nodes result in corresponding constraints on resources such as energy, memory, computational speed and bandwidth.

Fig. 1. Simple Block Diagram of a Sensor Node

II. OBJECTIVES AND CONTRIBUTIONS OF THIS PAPER

This paper has two main objectives and some contribution based on them. The first objective is to study the relations of topology control techniques and energy consumption in the Wireless Sensor Networks. Also, we studied MAC layer and different routing protocols for the wireless ad-hoc and sensor networks to understand their role in energy consumption while deployed with sensor nodes with movements. The second objective was to design some simulation scenarios using Network Simulator 2 (NS2) based on our study to confirm our findings. We have used several simulation scenarios using NS2 for this purpose. Our contribution is to establish the relation between the consumed energy and the routing protocol used in the Wireless Sensor Network.

The rest of the paper is organized as follows. We provide some brief description on topology control and routing protocols in section III. In section IV, we explained the simulation scenarios, settings and parameters used in our simulations done in NS2. Section V covers the results and outcomes of the simulations and our observations and findings from them. Finally, we concluded in section VI.

III. TOPOLOGY CONTROL

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Topology control is the art of coordinating node‘s decisions regarding their transmitting ranges, in order to generate a network with the desired properties or connectivity while reducing node energy consumption and/or increasing network capacity [2]. Due to the limited power and memory, a wireless node prefers to only maintain the information of a subset of neighbours it can communicate, which is called topology control. Topology control is implemented in the protocol stack and can be considered as an additional protocol layer positioned between the routing layer and MAC (Medium Access Control) layer [3].

Fig. 2. The Envisaged Location of Topology control Layer

A. Topology Control Using Routing And MAC Layer

The routing layer is responsible for finding and maintaining the routes between source/destination pairs in the network and forwarding packets toward the destination at the intermediate nodes on the route. The topology control protocol, which creates and maintains the list of the immediate neighbours of a node, can trigger a route update phase in case it detects that the neighbour list is considerably changed. On the other hand, the MAC layer can trigger re-execution of the topology control protocol in case it discovers new neighbour nodes. Since the life-time of the WSN depends on energy resources and their consumption by sensors, the energy consideration has a great influence on route design. The power consumed during transmission is the greatest portion of energy consumption of any node [4]. The MAC layer is responsible for regulating the access to the wireless, shared channel. It is important to correctly set the transmit power levels at the MAC layer. This important task should be performed by the topology control layer, which, having a network wide perspective, can take the correct decisions about the node‘s transmitting range. A MAC layer protocol proposed for the sensor networks should comply with the distinguishing sensor network properties.

Here, the most important attribute is energy efficiency. There are other secondary attributes and there will be generally some trade-off between those secondary attributes and energy efficiency [5].

B. Routing Techniques And Protocols

Routing is the process of selecting paths in a network along which to send network traffic. The routing process usually directs forwarding on the basis of routing tables which maintain a record of the routes to various network destinations. Many different routing techniques or algorithms are used in different types of network. WSN use distributed routing algorithms. The routing table stores the routes to particular network destinations. This information contains the topology of the network immediately around it. A routing protocol shares this information first among immediate neighbours, and then throughout the network. This way, routers gain knowledge of the topology of the network. The construction of routing tables is the primary goal of routing protocols. For WSN the widely used basic routing protocols are AODV, DSDV and DSR. In the following subsections, we‘ll briefly describe the key features of the DSDV, DSR and AODV protocols.

C. Destination-Sequenced Distance Vector (DSDV)

DSDV is a hop-by-hop distance vector routing protocol requiring each node to periodically broadcast routing updates. In this routing protocol routing messages are exchanged between neighbouring nodes. Routing updates are triggered in case routing information from one of the neighbours forces a change in the routing table. A packet for which the route to its destination is not known is cached while routing queries are sent out. The packets are cached until route-replies are received from the destination [6].

D. Dynamic Source Routing (DSR)

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E. Ad Hoc On-Demand Distance Vector (AODV)

AODV is a combination of both DSR and DSDV protocols. It borrows the basic on-demand mechanism of Route Discovery and Route Maintenance from DSR, plus the use of hop-by-hop routing, sequence numbers, and periodic beacons from DSDV [6]. AODV is capable of both unicast and multicast routing. It is a reactive routing protocol, meaning that it establishes a route to a destination only on demand.

IV. SIMULATION PROCEDURE

We have used Network Simulator 2 (NS-2) for the simulations. The version of NS-2 used for simulation is ns-allinone version 2.35 [9]. NS was built in C++ and provides a simulation interface through OTcl, an object-oriented version of Tcl (Tool Command Language). Our codes for defining the simulation scenarios are written in Tcl. A program called Network Animator (NAM) was used for visualizing the simulation.

A. Energy Models

The Energy Model implemented in NS-2 is a node attribute. In this energy model, a node has an initial value which is the level of energy the node has at the beginning of the simulation. It also has a given energy usage for every packet it transmits and receives. The energy model of NS-2 calculates the energy consumed by the sensor nodes using following equations.

E = Tx + Rx + Ix (1)

Tx = n × (Txb × b) + (A × a) (2)

Rx = n × (Rxb × b) (3)

Where,

E = Total energy consumed in a second, Tx = Energy to transmit,

Rx = Energy to receive,

Ix = Idle time energy,

n = Number of transmission in a second, b = Number of bit transferred,

A = Amplification energy, a = Area

B. Simulation Settings

For the simulations, at first we considered some simulation settings defining MAC layer and other properties of the sensor nodes. The simulation settings are summarized in Table I.

TABLEI SIMULATION SETTINGS

Description Parameter

Area of Deployment 500x500 meter Link bandwidth between peer nodes 1Mb

Propagation Model Two Ray Ground Propagation Delay between messages 5 seconds

Total size of the packet 512 bytes Transmission amplification cost for

radio transmitter 1.5 micro joule/bit/m

2

Transmission cost for running the

radio circuitry per bits processed 2.4 micro joule/bit Reception cost for running the radio

circuitry per bit processed 2.0 micro joule/bit The cost for a mote to be in its idle

state

1000 micro joule/second The initial energy each mote is given 15000 Milli Joule

The number of nodes in the network 4, 8, 25, 50

C. The Simulation Scenario

For the simulations, we have used some very simple Wireless Sensor Network Scenario. We took a defined area and deployed 4, 10, 25 and 50 sensor nodes respectively. From Fig 3 and Fig 4 we can have an overview of different stages of our simulation scenarios using 8 nodes and 4 nodes respectively. The simulation scenarios are visualized by NAM. For emulate mobility, we have assign some random motions to the sensor nodes. Status of each node can be understood from the present colour of the node. Green nodes have full or satisfactory energy level, Yellow nodes represent low energy level and Red means disabled node due to the complete depletion of energy.

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Fig. 4. A Simple Simulation Scenario with 4 mobile nodes

V. SIMULATION RESULTS AND PERFORMANCE ANALYSIS

In this section we have analysed the data found from the simulations and then evaluated their performances on the basis of energy usage. We ran our simulations using 4, 8, 25, 50 nodes and for all cases we observed similar outcomes. Due to huge datasets for the simulations using 8, 25 and 50 nodes, only the simulation results with 4 nodes are covered in this paper. In the Table II, III and IV the Energy usage of the sensor nodes are shown which is extracted from the simulation trace files generated by NS2. When, a sensor node depleted all of its energy it is marked as an ―OFF‖ node in the following data tables. For faster simulation result the nodes are assigned with only 15000 mJ of Energy which is much higher depending on the type of power source and sensor node. As the nodes are assigned with random motions, the energy usage can vary depending on the mobility of the nodes.

Table II.

Simulation Result of AODV Routing Protocol

Time in Minutes

Energy Used by Nodes (mJ) Node 0 Node 1 Node 2 Node 3 5 1584 2076 2076 600

10 3660 3660 4368 2676

15 5736 5736 5952 4752

20 7812 8304 8520 6336

25 9888 10380 10596 6936

30 11964 11964 12672 9012

35 14040 13548 14748 11088

40 14640 OFF OFF 12672

45 OFF OFF OFF 13272

50 OFF OFF OFF 13872

55 OFF OFF OFF 14472

60 OFF OFF OFF OFF

From Table II, we can see the energy uses of sensor nodes when using AODV as the routing protocol. We can see, for this setting with 4 sensor nodes, the node 2 and node 3 deactivates after 35 minutes of operation, while the last node deactivates after 55 minutes of operation.

Table III.

Simulation Result of DSDV Routing Protocol

Time in Minutes

Energy Used by Nodes (mJ) Node 0 Node 1 Node 2 Node 3 5 2076 2568 2568 2076

10 4152 4152 4644 4152

15 6228 6720 6720 6228

20 8304 9288 9288 7812

25 10872 11856 12348 10380

30 12948 13932 14916 12456

35 14976 OFF OFF 14496

40 OFF OFF OFF OFF

In case of using DSDV as routing protocol for the same scenario with 4 nodes, we can observe the energy usage of the nodes from Table III. Here, Node 1 and Node 2 deactivates after operating for 30 minutes and last two nodes goes to OFF state after working for 35 minutes.

Table IV.

Simulation Result of DSR Routing Protocol

Time in Minutes

Energy Used by Nodes (mJ) Node 0 Node 1 Node 2 Node 3 5 1434 1926 1926 450

10 3360 3360 4068 2376

15 5286 5286 5502 4302

20 7212 7704 7920 5736

25 9138 9630 9846 4986

30 11040 11040 11772 8112

35 12990 12498 13698 10038

40 13440 14400 OFF 11472

45 14874 OFF OFF 11922

50 OFF OFF OFF 12372

55 OFF OFF OFF 12816

60 OFF OFF OFF 14256

65 OFF OFF OFF OFF

In Table IV, we can see that while using DSR as the routing protocol, node 2 deactivated at first after performing for 35 minutes. The last node of the wireless sensor network goes to OFF state after working for an hour.

A. Comparison of AODV, DSDV, DSR protocol based on Simulation Data

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Table V.

Comparative Evaluation of Routing Protocols for WSN based on Simulation Data

Time in Minutes

Number of Active Nodes

AODV DSDV DSR

0 4 4 4

5 4 4 4

10 4 4 4

15 4 4 4

20 4 4 4

25 4 4 4

30 4 4 4

35 4 2 4

40 2 0 3

45 1 0 2

50 1 0 1

55 1 0 1

60 1 0 1

65 0 0 0

Fig. 5. Comparison of AODV, DSDV and DSR protocol

B. Analysis and Evaluation of Data

By analysing the simulation data found from our simulation scenario of 4-node WSN, it can decided that using DSR as routing protocol gives us longer lifetime for the nodes and thus the whole WSN. Also while using DSDV and AODV as routing protocol, AODV has much better performance than DSDV. For this 4-node WSN AODV and DSR has almost same performance. But, while we used more sensor nodes with wider area and further complicated setting, the difference of performance of these routing protocol becomes more prominent. But, it can be decided doubtlessly from all out simulation with 4, 8, 25 and 50 nodes, that DSR has the best performance in term of energy efficiency for these types of Wireless Sensor Networks.

VI. FUTURE WORKS

Here we only considered the MAC layer properties and routing protocols and their roles in energy efficiency in wireless sensor networks. Other factor can be considered for energy efficiency of wireless sensor networks. Also, for simulation purpose we only considered the basic routing protocols for simplicity. There are newer and more efficient routing protocols which can be used for simulation for a wider scope of observation. Although we performed our simulations using up to fifty sensor nodes, due to the large size of the datasets aren‘t be presented in this paper. But, our final observations are based on all our simulations as all of them provided similar results. As a future work, we want to consider more complicated simulation settings with more sensor nodes and wider ranges of routing protocols.

VII. CONCLUSION

In this paper, we have studied the MAC layer properties of sensor nodes and the use of different routing protocol to determine an energy efficient setting for Wireless Sensor Networks with mobile nodes. Based on our study of the MAC layer property of sensor nodes and routing protocols we designed some simulation scenario to determine the role of routing protocols on energy efficiency. We defined the MAC layer properties on which the energy consumption of the sensor nodes depends and selected AODV, DSDV and DSR, which are basic routing protocols for wireless sensor networks. We have analysed the simulation results to calculate the energy consumption by the mobile sensor nodes. From the data tables and charts derived from the simulation traces, we found that DSR routing protocol has the best performance on the basis of energy consumption and AODV is the second best. On the other hand, for all our simulation scenarios DSDV was observed as the most energy consuming routing protocol of the three we have considered in our study.

REFERENCES

[1] Hill, J.L. 2003. System Architecture for Wireless Sensor Networks.

University of California, Berkeley, spring 2003.

[2] Paolo, S. 2005. Topology Control in Wireless Ad Hoc and Sensor

Networks. ACM Comp. Surveys, Vol. 37, n. 2, pp. 164-194.

[3] Kousha, M.N and Xiang-Yang, L. 2005. Low-Interference Topology

Control for Wireless Ad Hoc Networks. Ad Hoc & Sensor Wireless Networks, March 3, 2005, Vol. 1, pp. 41–64.

[4] Mine, Y. 2007. Duty Cycle Control in Wireless Sensor Networks.

The Graduate School of Natural and Applied Science, Middle East Technical University.

[5] Javier, B. 2005. Investigating MAC Power Consumption in Wireless

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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 3, Issue 4, April 2013)

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[6] The ns Manual. 2008. The VINT Project, ed. Kevin Fall and Kannan

Varadhan, May 19, 2008.

[7] Culler, D, Estrin, D. and Srivastava, M. 2004. Overview of Sensor Networks. IEEE Computer Society, August 2004, pp. 41–49.

[8] Alonso, J. Gómez, S. Alejandrez, M. Gil, M and Navarro, N. 2006.

Experimental Measurements of the Power Consumption for Wireless Sensor Networks. Computer Architecture Department, Universitat Politècnica de Catalunya, June 26, 2006.

Figure

Fig. 1. Simple Block Diagram of a Sensor Node
Fig. 1. Simple Block Diagram of a Sensor Node p.1
TABLE IMULATION I SETTINGS

TABLE IMULATION

I SETTINGS p.3
Fig. 3. A Simple Simulation Scenario with 8 mobile nodes
Fig. 3. A Simple Simulation Scenario with 8 mobile nodes p.3
Table III. Simulation Result of DSDV Routing Protocol

Table III.

Simulation Result of DSDV Routing Protocol p.4
Fig. 4. A Simple Simulation Scenario with 4 mobile nodes
Fig. 4. A Simple Simulation Scenario with 4 mobile nodes p.4
Table IV. Simulation Result of DSR Routing Protocol

Table IV.

Simulation Result of DSR Routing Protocol p.4
Fig. 5. Comparison of AODV, DSDV and DSR protocol
Fig. 5. Comparison of AODV, DSDV and DSR protocol p.5

References