50120130406009 2

International Journal of Computer Engineering and Technology (IJCET), ISSN 0976-6367(Print),

ISSN 0976 - 6375(Online), Volume 4, Issue 6, November - December (2013), © IAEME

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ANALYSIS THE IMPROVEMENT PERFORMANCE OF WLAN

STANDARDS FOR MULTIMEDIA APPLICATIONS WITH MULTIPLE

SUBNET SCENARIOS

Dr. Adnan Hussein Ali* Dr. Hassan S. Hamad** Amal Ibrahim Mahmood*

*College of Electrical & Electronics Engineering Techniques - Baghdad

**Tech. Trainers preparing Institute - Baghdad

ABSTRACT

As the rapid growth of multimedia application over Internet, it is required to maintain the

Quality of Service (QoS), which is ensuring the guaranteed service through Internet and representing

the biggest challenges for the current IP based service. Multimedia traffic usage has been increased

in relation to the streaming media such as video conferencing. By using OPNET, the performance

can be simulated having heavy and light scenarios for video conferencing including web traffic.The

overall WLAN load data is obtained for such scenarios, further we also measured the performance of

Simulated Overall Delay in the Three scenario Networks.

1. INTRODUCTION

The wireless networks can be used to provide network connectivity nearly anywhere, it

provides large companies with an option to connect the usual wired networks to the new wireless

network without any problems and allows user the option to use any type of applications regardless

of its source or dealers [1]. Future Wireless local area networks(WLAN) enable people mobility to

communicate with everybody in the world at any time with a set of multimedia services.

However, the performance of the WLAN is a major factor in spreading and the use of such

technologies, as well as WLAN be more bandwidth limited as compared with the wired networks

because they supported on an inexpensive, physical medium (air). The exponential growth of cellular

telephones and mobile systems coupled with spreading of laptops and PDAs indicate a bright future

for such networks both as an independent as well as network infrastructures[2].So that it is important

to recover their performance. The limited use of standard and off-the-shelf technologies poses

serious limits related inter operability; moreover, many jurisdictions still use outdated equipment or

INTERNATIONAL JOURNAL OF COMPUTER ENGINEERING &

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ISSN 0976 – 6367(Print)

ISSN 0976 – 6375(Online)

Volume 4, Issue 6, November - December (2013), pp. 83-94

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infrastructures (e.g., analog radios, used to provide only voice service), which can’t enable an

effective emergency response now.

Hence, the design of a modern public safety system, and of a framework emergency network

architecture, requires to carefully consider the support to several different applications and services,

together with state-of-the-art ICT technologies. This can be translated into the finding of the best set

of applications and technologies that can provide the most effective response to crisis events.

Consequently, we represents a preliminary work regarding the study of the performance achievable

by a network architecture and by the considered communication technologies, in terms of Quality of

Service QoS. More in detail, identified the communication services necessary to be provided in any

network and analyzed them in order to determine their band width requirements. Then, the next step

has consisted in simulative tests in order to assess if each network segment composing the proposed

architecture, as well as the proposed communication technologies, can effectively support all the

considered emergency network services, providing adequate QoS [3]. These results could be used to

practically implement call admission control procedures.

2. RTS/CTS MECHANISM

The wireless station which ready to transmit data is made to send a short Request To Send

(RTS) frame before each data frame transmission. A collision of the RTS frame is less likely than the

collision of the actual data frame because there is a difference in size. If the receiver station is ready

to receive, it admits the RTS frame by sending a Clear To Send (CTS) frame to the sender and thus

blocks every movement from other wireless stations. When the source receives the CTS frame, it

sends the data frame as the channel has been allocated for the entire duration of transmission.

Finally, the receiver sends the ACK frame to the sender on receipt the frame [4]. So, it is important

to assess the efficiency of optional RTS/CTS handshake mechanism on the performance to analyze

the IEEE 802.11 based Wireless Local Area Networks (WLANs).

3. OPNET IMPLEMENTATION AND SIMULATION

Simulation modeling is becoming an increasingly popular approach to study the functionality

and performance of proposed models in several fields.

The flowchart of simulation of any system that has been begun by the steps that is taken in

the simulation process. For each scenario, the network traffic, configurations are modified and the

simulation is run. A flowchart is used to illustrate the key steps taken to evaluate the performance of

a wireless local area network is shown in Figure 1 [5].

Simulation is the process of testing a designed model on a platform which imitates the real

environment. It provides the opportunity to create modify and study the behavior of proposed design

so that one can expect its strengths and weakness before implementing the model in real

environment.



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Figure 1: Flow chart to evaluate the performance of WLAN

3.1 Baseline Scenario

The Baseline Scenario of 802.11g model was created using a variation of the OPNET 14.5

standard models WLAN deployment scenario. In this scenario, the behavior of a single infrastructure

802.11g WLAN is examined within the framework of a deployed WAN to better emulate the

configuration of an actual network [6].

An Internet Protocol IP cloud used to represent the backbone Internet is connected with a

Point-to-Point T1 (1.544Mbps) serial link. The three subnet are located on the other side of this IP

cloud via an IP gateway connected by Point-to-Point Protocol T1 link and two servers connected

through a central switch using 100BaseT, as shown in Figure 2, and wireless as shown in figure 3.

Create a new project

Create / Edit Scenario Model

Simulation Set Up

Results Analysis

Duplicate Scenario New Hypothesis (what-if)

Run Simulation

Selected Statistics To Collect



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.

Figure 2: Simulated Wire Server Frameworks

Figure 3: Simulated Wireless Server Frameworks

The subnet one located on the one side of this Internet Protocol (IP) cloud and the network’s

traffic servers are connected by 100BaseT Ethernet ,these servers connect to the firewall using

100BaseT Ethernet wiring and are used as the source and destination of all services: Hypertext

Transfer Protocol (HTTP), File Transfer protocol (FTP), video conferencing , voice applications,

Electronic Mail (E-mail) and Database running on the entire network representing traffic that is

exchanged with the mobile nodes in the 802.11g WLAN during the simulation [7][8], as shown in

Figure 4.



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Figure 4: Subnet 1 802.11g WLAN

The subnet two represents the remote branch office comprising an office_LAN having five

workstations connected by a 100BaseT link. Office LAN connected through a central switch using

100BaseT Ethernet wiring emulating a real life office environment with a standard Fast Ethernet

LAN. An IP gateway connects the LAN to an IP cloud, the gateway connects to the office LAN

using 100BaseT Ethernet wiring while the connection between the gateway and the IP cloud is done

with a Point-to-Point T1 serial link, as shown in Figure 5.

Figure 5: Subnet 2 802.11g WLAN

Finally, the subnet three located on the another side of the Internet Protocol cloud, the

WLAN is connected via its access point to an office LAN through a central switch using Ethernet

wiring emulating a real life office environment with a standard Fast Ethernet LAN having a WLAN

extension to an area of cabling difficulty or requiring aesthetics e.g. a conference or media room, as

shown in Figure 6.



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Figure 6: Subnet 3 Offices WLAN

The office_LAN are divided equally amongst the profiles, with each profile having one

workstations. Here the main objective is to analyses the user perceived performance of the WLAN

users, the WLAN sub network with five mobile nodes are assigned to different profiles as shown in

Table 1.

Table 1: Assigned profiles of mobile nodes in WLAN sub network

MOBILE NODE USER PROFILE

Station_1 Engineer

Station_2 Researcher

Station_3 E-commerce Customer

Station_4 Sales Person

Station_5 Multimedia User

3.2 Multimedia Load Scenarios

Multimedia traffic is introduced into the network in the form of video conferencing, Video

conferencing encompasses data, voice and images, and represents the ultimate multimedia

traffic[9][10]. A video server is introduced to serve video conferencing applications across the

network details, the applications configured for multimedia user profile in the multimedia load

scenarios as shown in Figure 7.



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Figure 7: Application Configurations for Multimedia User Profile

A number of model performance statistics, several are critical indicators used to determine

that the model operated correctly.

4. SIMULATION RESULTS AND DISCUSSIONS

4.1 Load A first parameter that influences the overall performance of the wireless standards is load.

The load test is concerned with the receipt of the payload data without considering overhead of

network against load. The total load on the WLAN as a function of time as the simulation progressed

is one of the more important results, The overall WLAN load data an approximate average value of

scenario heavy is (430.7407) Kbps on the 5 minute mark and the average value of scenario light

WLAN is (3622787) Kbps on the 5 minute mark and Figure 8shows the results belong to the first

scenario.

Figure 8: Total Loads on the Simulated Wireless LAN

A simulation scenario (heavy) was built and run in order to obtain the desired results for

individual load as shown in figure 9.



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Figure 9: Individual Load Values

A simulation scenario (Light) was built and run in order to obtain the results for Individual

Load Values for subnet, as shown in figure 10.

Figure 10: Individual Load Values for scenario (light) subnet one, subnet three



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In order to obtain the desired results of the load and the access point are illustrated

approximate average peak values stations to achieve the objective, A simulation scenario (heavy)

and the simulation scenario (Light) are shown in Table 2 .

Table 2: The Individual load values scenario 1(light) and scenario 2(heavy)

Type Of Node

WLAN Load

(Heavy) (Kbps)

subnet one

WLAN Load

(Heavy) (Kbps)

subnet three

WLAN Load

(Light) (Kbps)

subnet one

WLAN Load

(Light)(Kbps)

subnet three

Access point (AP2) 42.07 (AP1) 200.2 (AP1) 916124 (AP3) 899128

E-commerce

costumer 0 188.4 73 146

Engineer 0 0 223 232

Researcher 0 0 202 260

Video

conferencing 0 0 893783 87652

Voice 0 0 17878 18201

Sub Value 42.07 388.6 1828285 1794502

Sum total 430.7407407 3622787.467

4.2 Delay Delay is an essential metric to characterize the QoS of any network, especially for real time

Multimedia application. It represents an important parameter in determining the successful operation

of the MAC layer, its timing operations, and the Required To Send/ Clear To Send (RTS/CTS)

mechanism are the medium access delay and overall packet transmission delay statistics, those

results average overall WLAN delay peaks at 0.0125s, these values are typical of an efficient WLAN

under normal traffic loads, are displayed in Figure 11.

Figure 11: Simulated Overall Delay in the Three scenario Networks



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While the average (in Video conferencing packet End-to- End Delay (sec)) delay peaks at

(0.055s) as shown in figure 12.

Figure 12 Simulated Video conferencing Wire server Delay VS Wireless server Delay

It appears the WLAN Delay which represents the end to end delay of all the packets obtained

by the wireless LAN MACs of all nodes of Wireless LAN in the network and forwarded to the

higher layer. E2E delay includes medium access delay at the source MAC, reception of all the parts

individually. It is shown that WLAN Delay is very high through those retransmissions.

The average (in Voice packet End-to-End Delay (sec)) delay peaks at (0.093s) as shown in

figure 13.

Figure 13 Simulated Voice Wire server Delay VS Wireless server Delay

A simulation different WLAN Delay of applications are used and simulation scenario 1

(Light) Wire Server (0.0103(sec)) vs Wireless Server (0.0125(sec))as shown in figure 14.



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Figure 14 Simulated WLAN Delay (sec) Wireless servervs Wire server

The delay and the access point are illustrated approximate average peak valuesas shown in Table 3.

Table 3 Wireless LAN delay (sec) Server of applications in WLAN

Application Wireless server

Delay(sec)

Wire server

Delay(sec)

Video

conferencing 0.039 0.055

Voice 0.082 0.093

5. CONCLUSION

Quality of Service techniques are applied in IP networks to employ available network

resources in the most efficient manner to minimize delays innet work traffic having multiple type of

multimedia services which may include voice, video and database.

Two network scenarios have been created namely 1 heavy network, Scenario 2(Medium

Load) network and Scenario 3(High Load) network. Comparison were carried out between them and

presented in Chapter 4.

Performance tests conducted were Delay and Load Performances, in these Performance tests,

we observed the results for two cases: heavy and light scenarios.

REFERENCES

[1] S. Ohmori, “The Future Generations of Mobile Communications Based on Broadband Access

Technologies”, IEEE Communications Magazine, 134 - 142, December 2000.

[2] Rahul, V. and Dr. R. K. Bansal. “Simulation & performance analysis of wired and wireless

computer networks”, International Journal of Computer Applications, February 2011.

[3] Navdeep Singh Chauhan, Loveljeet Kaur, “Evaluation of QoS for Different Voice Schemes

in Wireless LAN using OPNET Modular”, Int. J. on Recent Trends in Engineering &

Technology, Vol. 05, No. 01, Mar 2011.



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[4] Jasani H., Alaraje N. “ Evaluating the performance of IEEE 802.11 network using

RTS/CTS mechanism” IEEE International Conference on Electro/Information Technology,

2007

[5] IT Guru Academic Edition. OPNET Technologies, (2007)

http:// www.opnet.com/universityprogram/ itguru academic edition.

[6] N. Kritika, Namarta. “Performance Evaluation of 802.11 WLAN Scenarios in OPNET

Modeler” International Journal of Computer Applications, May 2011.

[6] Mahbubur, S.R , Multimedia Networking: Technology, management and applications, Idea

group publishing: London, 2002.

[7] Tsalianis,A, and Economides, A “Quality of service standards for distributed multimedia

applications “ pp 13-17,Available through: Googlescholar (Accessed 22 June 2011).

[8] Cerqueira, E., Zeadally, S., Leszczuk, M., Curado, M. & Mauthe, A. Recent advances in

multimedia networking, Multimedia Tools and Applications” pp. 1–13, 2008.

[9] Ciurana, M., Barceló-Arroyo, F. & Martín-Escalona, I.“Comparative performance evaluation

of IEEE 802.11 for positioning with time of arrival”, Computer Standards& Interfaces 33(3):

344 – 349, 2011.

[10] Klein, A. &Klaue, J. “ Performance evaluation framework for video applications in mobile

networks”, Second International Conference on Advances in Mesh Networks, MESH 2009,

IEEE, pp. 43–49, 2009.

[11] R. Rajan, S. Shipra, “WLAN Performance Improvisation by Fine Tuning IEEE 802.11

Parameters”, International Journal of Computer Applications, April 2012.

[12] N. Kritika, Namarta. “Performance Evaluation of 802.11 WLAN Scenarios in OPNET

Modeler” International Journal of Computer Applications, May 2011.

[13] Dr. Adnan Hussein Ali, Dalal Abdulmohsin Hammood and Amal Ibrahim Mahmood,

“Improvement of Ieee 802.11g WLANS Based on Response Times Application with Radio –

Fiber System”, International Journal of Electronics and Communication Engineering &

Technology (IJECET), Volume 4, Issue 5, 2013, pp. 161 - 168, ISSN Print: 0976- 6464,

ISSN Online: 0976 –6472.

[14] Dheyaa Jasim Kadhim and Sanaa Shaker Abed, “Performance and Handoff Evaluation of

Heterogeneous Wireless Networks (HWNS) using OPNET Simulator”, International Journal

of Electronics and Communication Engineering & Technology (IJECET), Volume 4, Issue 2,

2013, pp. 477 - 496, ISSN Print: 0976- 6464, ISSN Online: 0976 –6472.

[14] Neeraj Tiwari, Rahul Anshumali and Prabal Pratap Singh, “Wireless Sensor Networks:

Limitation, Layerwise Security Threats, Intruder Detection”, International Journal of

Electronics and Communication Engineering & Technology (IJECET), Volume 3, Issue 2,

2012, pp. 22 - 31, ISSN Print: 0976- 6464, ISSN Online: 0976 –6472.

AUTHOR’S PROFILE

The Author is a Lecturer in the Computer Engineering Department at Institute of

Technology, Baghdad, IRAQ. He has been awarded a Doctor of Philosophy in

Laser and Opto-Electronics Engineering from University of Technology,

Baghdad, in 2007. He has studied Master of Science in Electronics Engineering,

Cupper Vapor Laser's Power supply at University of Technology, Baghdad in

2000. He has gained Bachelor in Electrical and Electronic Engineering from

University of Technology, Baghdad, in 1987. Currently he is the Deputy Dean of

Institute of Technology, Baghdad, IRAQ. His research interests are Radio over

Fiber, Wireless Network, Laser's Power supply and OPNET.

50120130406009 2

Technology

rts frame

wireless networks

cts frame

data frame transmission

ack frame

actual data frame

new wireless network

performance achievable