performance evaluation of the wsn routing protocols

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Hindawi Publishing Corporation Journal of Computer Systems, Networks, and Communications Volume 2008, Article ID 481046, 9 pages doi:10.1155/2008/481046 Research Article Performance Evaluation of the WSN Routing Protocols Scalability L. Alazzawi and A. Elkateeb Electrical and Computer Engineering Department, College of Engineering, University of Michigan, Dearborn, MI48128-2406, USA Correspondence should be addressed to A. Elkateeb, [email protected]. Received 22 July 2008; Accepted 23 December 2008 Recommended by Cheng-Xiang Wang Scalability is an important factor in designing an ecient routing protocol for wireless sensor networks (WSNs). A good routing protocol has to be scalable and adaptive to the changes in the network topology. Thus scalable protocol should perform well as the network grows larger or as the workload increases. In this paper, routing protocols for wireless sensor networks are simulated and their performances are evaluated to determine their capability for supporting network scalability. Copyright © 2008 L. Alazzawi and A. Elkateeb. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 1. INTRODUCTION Sensor networks consist of a large number of small sensor devices that have the capability to take various measurements of their environment. For instance, such measurements can include acoustic, magnetic, and video information. Each of these devices is equipped with a small processor and wireless communication antenna and is powered by a battery making it very resource constrained. These sensors are typically scattered around a sensing field to collect information about their surroundings. Deferent routing protocols are designed and imple- mented for WSNs [1]. The design of these routing protocols is influenced by many factors where the scalability factor is considered as one of these important factors. The sensor net- works scalability is the ability to support network expansion to include more nodes that might not be anticipated during the initial network design stage. Therefore, the routing protocols used for wireless sensor networks should support network scalability where such protocols should continue to perform well as the network grows larger or as the workload increases [2]. As the routing packets within a large-scale wireless sensor network occur on nodes that have very limited resources of packets storage and updates routing table processing, the routing processing has become a very challenging issue. Therefore, in order to constrain such limitations, ecient and scalable routing protocols design is required for routing packets in sensor networks [2]. Such routing protocols should avoid degrading the performance of the wireless sensor networks as the network expanding. The evaluation of the scalability issue with wireless sensor networks is a real challenge due to the variety of routing protocols, the large nodes number, and the wide range of sensor networks applications. Therefore, the evaluation of the sensor networks scalability is not practically feasible over a real network, and using network simulator will provide a meaningful perspective into the study of the sensor networks scalability [3]. Thus the goal of this paper is to develop a detailed simulation framework, which can accurately model dierent sensor networks routing protocols. 2. ROUTING PROTOCOLS FOR SCALABILITY EVALUATION Many routing protocols have been proposed for routing data in wireless sensor networks. These routing protocols have considered the characteristics of sensor nodes along with the application and architecture requirements [4]. Three dierent protocols have been selected in this evaluation study: the flooding protocol (FP) [5], the beacon vector

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Hindawi Publishing CorporationJournal of Computer Systems, Networks, and CommunicationsVolume 2008, Article ID 481046, 9 pagesdoi:10.1155/2008/481046

Research ArticlePerformance Evaluation of the WSNRouting Protocols Scalability

L. Alazzawi and A. Elkateeb

Electrical and Computer Engineering Department, College of Engineering, University of Michigan,Dearborn, MI48128-2406, USA

Correspondence should be addressed to A. Elkateeb, [email protected].

Received 22 July 2008; Accepted 23 December 2008

Recommended by Cheng-Xiang Wang

Scalability is an important factor in designing an efficient routing protocol for wireless sensor networks (WSNs). A good routingprotocol has to be scalable and adaptive to the changes in the network topology. Thus scalable protocol should perform well as thenetwork grows larger or as the workload increases. In this paper, routing protocols for wireless sensor networks are simulated andtheir performances are evaluated to determine their capability for supporting network scalability.

Copyright © 2008 L. Alazzawi and A. Elkateeb. This is an open access article distributed under the Creative Commons AttributionLicense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properlycited.

1. INTRODUCTION

Sensor networks consist of a large number of small sensordevices that have the capability to take various measurementsof their environment. For instance, such measurements caninclude acoustic, magnetic, and video information. Each ofthese devices is equipped with a small processor and wirelesscommunication antenna and is powered by a battery makingit very resource constrained. These sensors are typicallyscattered around a sensing field to collect information abouttheir surroundings.

Deferent routing protocols are designed and imple-mented for WSNs [1]. The design of these routing protocolsis influenced by many factors where the scalability factor isconsidered as one of these important factors. The sensor net-works scalability is the ability to support network expansionto include more nodes that might not be anticipated duringthe initial network design stage. Therefore, the routingprotocols used for wireless sensor networks should supportnetwork scalability where such protocols should continue toperform well as the network grows larger or as the workloadincreases [2].

As the routing packets within a large-scale wireless sensornetwork occur on nodes that have very limited resourcesof packets storage and updates routing table processing,the routing processing has become a very challenging issue.

Therefore, in order to constrain such limitations, efficientand scalable routing protocols design is required for routingpackets in sensor networks [2]. Such routing protocolsshould avoid degrading the performance of the wirelesssensor networks as the network expanding.

The evaluation of the scalability issue with wirelesssensor networks is a real challenge due to the varietyof routing protocols, the large nodes number, and thewide range of sensor networks applications. Therefore, theevaluation of the sensor networks scalability is not practicallyfeasible over a real network, and using network simulatorwill provide a meaningful perspective into the study ofthe sensor networks scalability [3]. Thus the goal of thispaper is to develop a detailed simulation framework, whichcan accurately model different sensor networks routingprotocols.

2. ROUTING PROTOCOLS FORSCALABILITY EVALUATION

Many routing protocols have been proposed for routing datain wireless sensor networks. These routing protocols haveconsidered the characteristics of sensor nodes along withthe application and architecture requirements [4]. Threedifferent protocols have been selected in this evaluationstudy: the flooding protocol (FP) [5], the beacon vector

2 Journal of Computer Systems, Networks, and Communications

Adapting routing protocol

Flooding protocolBeacon vector

routing protocolProbabilistic

geographic routing

Each node receivinga data repeats it by

broadcasting

Nodes route packetsusing greedily

forwarding

Nodes route packetsusing angle routing

discovery

Does not requirecomplex route

discovery algorithms

Nodes assignedpositions based on

connectivity

Nodes equipped withGPS or some otherlocalization scheme

Figure 1: Selected routing protocols for scalability evaluation.

Performance metrics

Networkdelay Throughput Success rate Latency

Energyconsumption

Networklife time

Figure 2: A set of performance metrics.

routing protocol (BVR) [6], and the probabilistic geographicrouting protocol (PGR) [7] (see Figure 1). Using thesethree different protocols for evaluating scalability issue inWSNs can be expanded in future work to support otherprotocols.

The beacon vector routing protocol (BVR) is ahierarchical-based routing protocol which is assigned coor-dinates to the nodes based on the vector of hop countdistances to a small set of beacons, and defines distancemetric on these coordinates. The BVR routes packetsgreedily forwarding to the next hop. That is, the closestto the destination according to this beacon vector routing.The probabilistic geographic routing protocol (PGR) islocation-based routing that assumes each node is awareof its geographical coordinates through some localizationscheme, such as the GPS. The flooding protocol (FP) isone of the available flat-based routing protocols. In thisprotocol, each intermediate node that receives a packetsimply forwards it to all its neighbors until it reaches thedestination. Flooding protocol is selected because of thesimplicity of this flat protocol that can be used to com-pare other protocols scalability with this flooding protocol[4].

3. THE COMPARISON QUANTITATIVE METRICS

In order to compare FP, BVR, and PGR protocols’ scalability,the quantitative metrics are used to measure and evaluate theperformance of the simulated routing protocols. For all met-rics, the average over multiple experiments is determined.The set of performance metrics used for comparing the

selected routing protocols of this work is shown in Figure 2.Each of these metrics parameters can be described briefly asfollows [8].

(a) Network delay

This performance metric is used to measure the averageend-to-end delay of data packet transmission. The end-to-end delay implies the average time taken between a packetinitially sent by the source, and the time for successfullyreceiving the message at the destination. Measuring this delaytakes into account the queuing and the propagation delay ofthe packets.

(b) Network throughput

The end-to-end network throughput measures the numberof packets per second received at the destination. It isconsidered here as an external measure of the effectivenessof a protocol.

(c) Success rate

The total number of packets received at the destinationsverses the total number of packets sent from the source.

(d) Latency

The average message latency is defined as the average amountof time between the start of disseminating a data and itsarrival at a node interested in receiving the data. Hence,

L. Alazzawi and A. Elkateeb 3

the latency measures time performance for the individualmessage [9].

(e) Energy consumption

The energy consumption is the sum of used energy of all thenodes in the network, where the used energy of a node isthe sum of the energy used for communication, includingtransmitting (Pt), receiving (Pr), and idling (Pi). Assumingeach transmission consumes an energy unit, the total energyconsumption is equivalent to the total number of packetssent in the network.

(f) Network lifetime

It is considered as the time until message loss rate is abovea given threshold. The more complete definition for thelifetime of the network is “time to network partition” [10].Network partition occurs when there is a cut-set in thenetwork. It will be introduced as a new metric, which willuse energy variance:

Network lifetime = E − (U + σ),

where U = ΣUi

N.

(1)

E is the total initial energy at each node (full batterycharge), Ui is the average used energy, N is the total numberof nodes in the network, and σ is expressed as

σ2 = (Ui −U)2

N. (2)

All these metrics are calculated using their cumulativeaverage values, that is, at time t, the performance value is theaverage from 0 to t (seconds) [11].

(g) Packet generation rate

It is the number of packets that the sensor node transmits inone time period which is usually one second.

4. SIMULATOR

Many network simulators are currently available such asSensorSim [12], TOSSIM [13], NS2 [14], OPNET [15].However, we decided to use the prowler simulator in thisresearch work because of our previous experience with thissimulator, easy to use, and it is available online [16].

We have used the prowler network simulator to evaluatethe protocols performance and specifically to measure theirscalability. A prowler is an event-driven tool that simulatesthe nondeterministic nature of the communication channeland the low-level communication protocol of the wirelesssensor nodes [4]. To produce replicable results while testingthe application, prowler can be set to operate in deterministicmode also. It can incorporate arbitrary number of nodes onarbitrary and even dynamic topology. Prowler models all theimportant aspects of the communication channel and theapplication. The tool is implemented in MATLAB, thus it

provides a fast and easy way to prototype applications, andhas nice visualization capabilities [10].

The nondeterministic nature of the radio propagationis characterized by a probabilistic radio channel model.The applications interact through a set of events andcommands just like in actual TinyOS applications. The radiopropagation model determines the RF signal strength at aparticular point in the space for all transmitters in the system.Based on this information, the signal reception conditions atthe receivers can be evaluated and collisions can be detected.Similarly to the real TinyOS framework, prowler applicationsare event based.

The simulator signals important events for the appli-cation code, such as initialization completed, packet sent,packet received, packet collided, and clock ticked. Theapplication in turn can initiate actions such as set clockand send packet. These can cause further events. Severaldebugging/visualization tools are also available, includingswitching mote LEDs on/off, drawing lines and arrows, andprinting text messages.

4.1. Protocols performance

A set of simulations are used to evaluate the performanceof the protocols: FP, BVR, and PGR. The simulations areall performed using prowler under the default radio modelσα = 45, σβ = 0.02, and perror = 0.05. The average radiorange of transmission was a radius of 10 m. However, theradio model in prowler was set up to model the transmissionrange as an imperfect circle. The network setup consistedof 100 nodes dispersed in an area depicting 100 m × 100 m.The simulations are run on random networks model, wherethe nodes placements are changed randomly in uniformlysquare area. The sensors are deployed in a regular grid withrandom offsets.

The performance of the protocols is evaluated undertwo setting referred to firstly in the relation of simulationtime in seconds with defiant quantitative metrics include(success rate, latency, and throughput. Secondly, it isreflected through the relation between average delays, totalthroughput, and total energy used. All the results are drivenfrom five runs for the random network models for eachof the three protocols. Figures 3, 4, 5, and 6 illustrate theperformance of the flooding protocol. Figures 7, 8, 9, and 10illustrate the performance of the PGR protocol and Figures11, 12, 13, and 14 illustrate the performance of the BVRprotocol.

4.1.1. Flooding protocol performance

Figures 3–6 are illustrating the flooding protocol perfor-mance.

4.1.2. PGR protocol performance

Figures 7–10 are illustrating the PGR protocol performance.

4.1.3. BVR protocol performance

Figures 11–14 are illustrating the BVR protocol performance.

4 Journal of Computer Systems, Networks, and Communications

Succ

ess

rate

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Simulation time (s)

5 10 15 20 25 30 35 40 45 50

Success rate flooding (:,1)Success rate flooding (:,2)Success rate flooding (:,3)Success rate flooding (:,4)Success rate flooding (:,5)

Figure 3: Simulation time and success rate.

Late

ncy

(s)

0

0.5

1

1.5

2

2.5

3

Simulation time (s)

5 10 15 20 25 30 35 40 45 50

Flooding latency (:,1)Flooding latency (:,2)Flooding latency (:,3)Flooding latency (:,4)Flooding latency (:,5)

Figure 4: Simulation time and latency.

4.2. Effects of routing metrics on the scalabilityaccording to the packet generation rate

The first study of the network scalability for the selectedrouting protocols is by using different packet generation

Th

rou

ghpu

t

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Simulation time (s)

5 10 15 20 25 30 35 40 45 50

Throughput flooding (:,1)Throughput flooding (:,2)Throughput flooding (:,3)Throughput flooding (:,4)Throughput flooding (:,5)

Figure 5: Simulation time and throughput.

Tota

len

ergy

use

d

0

100

200

300

400

500

600

Total throughput

0.65

0.60.55

0.5

Average delays1

1.52

2.53

Flooding protocol

Figure 6: Average delays—total throughput—total energy used.

rates in a prowler simulator. We randomly place 100 sensornodes in a 100 m× 100 m sensor field for each protocol. Thedefault prowler radio model is used. Each routing protocoltest is performed (with query and event locations randomlyselected) which, started by one packet and then increasedthe number of packets. In this section, performances ofthe selected routing protocols with increased workload areevaluated as follows.

L. Alazzawi and A. Elkateeb 5

Succ

ess

rate

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Simulation time (s)

5 10 15 20 25 30 35 40 45 50

Success rate PGR (:,1)Success rate PGR (:,2)Success rate PGR (:,3)Success rate PGR (:,4)Success rate PGR (:,5)

Figure 7: Simulation time and success rate.

Late

ncy

(s)

0

0.5

1

1.5

2

2.5

Simulation time (s)

5 10 15 20 25 30 35 40 45 50

PGR latency (:,1)PGR latency (:,2)PGR latency (:,3)PGR latency (:,4)PGR latency (:,5)

Figure 8: Simulation time and latency.

Figure 15 compares the energy used for the flooding,BVR, and PGR protocols with respect to packet generationrate. The results show that the energy used experienced byBVR protocol is lower than the other protocols.

The message latency can be an important parameter forthe scalability of the protocols. The intrinsic relative low

Th

rou

ghpu

t

0.5

1

1.5

2

2.5

3

Simulation time (s)

5 10 15 20 25 30 35 40 45 50

PGR throughput (:,1)PGR throughput (:,2)PGR throughput (:,3)PGR throughput (:,4)PGR throughput (:,5)

Figure 9: Simulation time and throughput.

Tota

len

ergy

use

d

0

100

200

300

400

Total throughput

3

2.5

2 Average delays

0.20.25

0.30.35

0.4

PGR protocol

Figure 10: Average delays—total throughput—total energy used.

latency characteristic can be used as a tradeoff to extendthe network performance in accordance with the protocolconstraints. The BVR protocol gave the lowest latency amongthe PGR and flooding protocols with increasing the packetgeneration rate as shown in Figures 16.

With increasing the packet generation rate, the averagepacket delay in the flooding protocol gave the highest delayamong others as shown in Figure 17. As an average, thishighest value was 0.264 second. For the BVR protocol, thiswas the best because it gave much lower delay than the

6 Journal of Computer Systems, Networks, and CommunicationsSu

cces

sra

te

0.5

0.55

0.6

0.65

0.7

0.75

0.8

0.85

0.9

Simulation time (s)

5 10 15 20 25 30 35 40 45 50

BVR success rate (:,1)BVR success rate (:,2)BVR success rate (:,3)BVR success rate (:,4)BVR success rate (:,5)

Figure 11: Simulation time and success rate.

Late

ncy

(s)

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

Simulation time (s)

5 10 15 20 25 30 35 40 45 50

BVR latency (:,1)BVR latency (:,2)BVR latency (:,3)BVR latency (:,4)BVR latency (:,5)

Figure 12: Simulation time and latency.

two other protocols that intern it gave an average of (0.075)second.

Figure 18 shows the network lifetime of the three pro-tocols as the packet generation increases. We observe thatthe network lifetime of each protocol is decreased. TheBVR protocol was the longest network lifetime while the

Th

rou

ghpu

t

1

2

3

4

5

6

7

Simulation time (s)

5 10 15 20 25 30 35 40 45 50

BVR throughput (:,1)BVR throughput (:,2)BVR throughput (:,3)BVR throughput (:,4)BVR throughput (:,5)

Figure 13: The simulation time and throughput.

Tota

len

ergy

use

d

0

1

2

3

4×102

Total throughput

5.5

5

4.5

4

3.5

3Average delays0.09 0.1

0.11 0.12 0.130.14

0.15

BVR protocol

Figure 14: Average delays—total throughput—total energy used.

flooding protocol gave the shortest network lifetime. Thiswas expected since flooding is a very energy-consuming task.

4.3. Effects of routing metrics on the scalabilityaccording to the network size

This section turns our attention from the scalability to thebehavior of the protocols with respect to increasing the

L. Alazzawi and A. Elkateeb 7E

ner

gy

100

150

200

250

300

350

400

450

500

Packet generation rate

0 2 4 6 8 10 12 14 16 18 20

BVR protocolFlooding protocolPGR protocol

Figure 15: Energy test.

Late

ncy

(s)

0.5

0.55

0.6

0.65

0.7

0.75

0.8

0.85

0.9

0.95

1

Packet generation rate

0 2 4 6 8 10 12 14 16 18 20

Flooding protocolBVR protocolPGR protocol

Figure 16: Latency test.

number of nodes in the network. The transmission range ofeach mote is set to 10 units and runs the protocols with 50to 500 nodes in steps of 50 sensor nodes (motes placed) ina grid. From the observed performance metrics for each ofthese protocols with increasing of network size, we obtain thefollowing.

Del

ays

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

Packet generation rate

0 2 4 6 8 10 12 14 16 18 20

Flooding protocolBVR protocolPGR protocol

Figure 17: Average packet delay test.N

etw

ork

lifet

ime

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

5.5

Packet generation rate

0 2 4 6 8 10 12 14 16 18 20

Flooding protocolBVR protocolPGR protocol

Figure 18: Network lifetime test.

(i) The BVR protocol achieved the best success rate overdifferent network sizes in comparison with PGR andflooding protocols that gave a lower success rate,respectively, as shown in the Figure 19.

(ii) The average throughput for BVR was about 73% overdifferent network sizes as shown in Figure 20. Whilethe flooding protocol has about 43% throughput andPGR protocol has about 47% throughput when thenumber of sensor nodes in the networks is increased.

8 Journal of Computer Systems, Networks, and CommunicationsSu

cces

sra

te

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Number of nodes

50 100 150 200 250 300 350 400 450 500

BVR protocolPGR protocolFlooding protocol

Figure 19: Success rate test.

Th

rou

ghpu

t(%

)

20

30

40

50

60

70

80

90

Number of nodes

50 100 150 200 250 300 350 400 450 500

BVR protocolPGR protocolFlooding protocol

Figure 20: The throughput test.

(iii) The PGR protocol gave a lower latency than theflooding protocol with increasing of network sizeas shown in Figure 21. Among them the BVRprotocol gave the lowest latency with increasingthe network size.

(iv) The energy consumption of the BVR protocol wasthe lowest in comparison with the rest of protocolsaccording to the increasing number of nodes asshown in Figure 22.

Late

ncy

(s)

0

2

4

6

8

10

12

14

16

Number of nodes

50 100 150 200 250 300 350 400 450 500

BVR protocolPGR protocolFlooding protocol

Figure 21: Latency test.E

ner

gyco

nsu

mpt

ion

0

500

1000

1500

2000

2500

3000

3500

4000

Number of nodes

0 50 100 150 200 250 300 350 400 450 500

Flooding protocolPGR protocolBVR protocol

Figure 22: The energy consumption test.

5. CONCLUSIONS

In this work, three WSN protocols, namely, BVR, PGR,and FP were simulated using advance wireless sensorsimulator (prowler). Several tests were carried out usingdifferent network parameters of WSNs. The performanceof different routing protocols is measured to determine themost efficient one for the scalability. After evaluating severalmetrics which are throughput, latency, energy consumption,

L. Alazzawi and A. Elkateeb 9

and delay, it was found that the BVR protocol is the mostefficient scalable protocol.

REFERENCES

[1] M. Becker, S. Schaust, and E. Wittmann, “Performanceof routing protocols for real wireless sensor networks,” inProceedings of the 10th International Symposium on Perfor-mance Evaluation of Computer and Telecommunication Systems(SPECTS ’07), San Diego, Calif, USA, July 2007.

[2] Y. Eiko and J. Bacon, “Wireless sensor network technologies:research trends and middleware’s role,” Tech. Rep. UCAM-CL-TR-646, Computer Laboratory, University of Cambridge,Cambridge, UK, September 2005, http://www.cl.cam.ac.uk.

[3] X. Renyi and W. Guozheng, “A survey on routing in wirelesssensor networks,” Progress in Natural Science, vol. 17, no. 3, pp.261–269, 2007.

[4] G. Simon, P. Volgyesi, M. Maroti, and A. Ledeczi, “Simulation-based optimization of communication protocols for large-scale wireless sensor networks,” in Proceedings of IEEE Interna-tional Aerospace Conference (CDROM), vol. 3, pp. 1339–1346,Big Sky, Mont, USA, March 2003.

[5] A. Kini and V. Veeraraghavan, “Fast and Efficient RandomizedFlooding on Latticesensor Networks,” Center for Telecommu-nications and Information Networking group, 2004.

[6] R. Fonseca, “Beacon vector routing: towards scalable point-to-point routing in deeply embedded networks,” Final Report CS294-1, University of California, Berkeley, Calif, USA, 2003.

[7] T. Roosta and M. Menzo, “Probabilistic geographic routingprotocol for ad hoc and sensor networks,” Department ofEECS UC Berkeley, 2004.

[8] A. Hac, Wireless Sensor Network Design, John Wiley & Sons,New York, NY, USA, 2003.

[9] A. El Gamal, J. Mammen, B. Prabhakar, and D. Shah,“Throughput-delay trade-off in wireless networks,” in Pro-ceedings of the 23rd Annual Joint Conference of IEEE Computerand Communications Societies (INFOCOM ’04), vol. 1, pp.464–475, Hong Kong, March 2004.

[10] O. Chipara, Z. He, G. Xing, et al., “Real-time power-awarerouting in sensor networks,” in Proceedings of the 14th IEEEInternational Workshop on Quality of Service (IWQoS ’06), pp.83–92, New Haven, Conn, USA, June 2006.

[11] Y.-S. Yen, S. Hong, R.-S. Chang, and H.-C. Chao, “An energyefficient and coverage guaranteed wireless sensor network,”in Proceedings of the IEEE Wireless Communications andNetworking Conference (WCNC ’07), pp. 2923–2928, HongKong, March 2007.

[12] S. Park, A. Savvides, and M. B. Srivastava, “SensorSim: asimulation framework for sensor networks,” in Proceedings ofthe 3rd ACM International Workshop on Modeling, Analysis andSimulation of Wireless and Mobile Systems (MSWiM ’00), pp.104–111, Boston, Mass, USA, August 2000.

[13] P. Levis, N. Lee, M. Welsh, and D. Culler, “TOSSIM: accurateand scalable simulation of entire TinyOS applications,” inProceedings of the 1st International Conference on EmbeddedNetworked Sensor Systems (SenSys ’03), pp. 126–137, LosAngeles, Calif, USA, November 2003.

[14] “The ns manual,” The VINT project, November 2008,http://www.isi.edu/nsnam/ns/doc/ns doc.pdf.

[15] OPNET Technologies, Inc., Bethesda, Md, USA: The OPNETSimulator, http://www.opnet.com.

[16] “Prowler: Probabilistic Wireless Network Simulator,” In-stitute for Software Integrated Systems (ISIS), http://www.isis.vanderbilt.edu/projects/nest/prowler. .

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