Planning And Analysing Wlan Using Opnet Computer Science Essay

This is the 2nd, more advanced research lab exercising covering with web simulation and more specifically, with wireless webs. The exercising is based on an OPNETWORKS tutorial ( OPNETWWORKS is the official OPNET conference ) .

Students are expected to hold completed successfully the first OPNET simulation ( assignment 2.1 ) . For those of you missing experience, there is an introductory assignment that you can follow, in the Roentgen: thrust ( assignment 2a – cyberspace simulation – tutorial.pdf )

. There is besides an introductory slide show to be viewed before get downing this assignment. It will give you some basic apprehension of cardinal WLAN processs and the manner that OPNET trades with them. It will besides depict in more item the jobs posed in this assignment.

The assignment is divided in two parts: ( both are pre-created for your convenience )

Lab 1 trades with the “ concealed station ” job, a state of affairs where two WLAN terminuss can both “ see ” a 3rd one but non each other. As a consequence, they try to originate transmittal at the same clip and their packages collide and are destroyed. The state of affairs is resolved by the debut of two processs: Request To Send / Clear To Send ( RTS/CTS ) .

Lab 2 investigates the scenario of adding more Access Points ( AP ) on a given office infinite, in order to administer the traffic more equally, avoid major constrictions and better throughput.

Learning Results

After finishing this lab exercising you should be able to:

Set up a radio web utilizing OPNET.

Select specific properties of the WLAN to polish your Wireless local area network

Understand the impact of the RTS/CTS mechanism as a step to forestall the concealed node job

Become familiar with WLAN theoretical account attributes needed to configure BSSs

Be able to choose an appropriate WLAN topology harmonizing to the application traffic

2. Get downing OPNET

To get down OPNET under Windows XP/2000 execute the undermentioned stairss:

Travel to Start button and turn up under “ SED Software ” the group called OPNET modeler 14.5 ( or similar ) so click the point called OPNET modeler.

Wait until OPNET starts up and a valid licence is obtained from the web. Then click OK.

Make a directory and copy the files that come with this assignment ( WLAN directory ) in your abrasion thrust ( either D: or your personal disc infinite ) . Within OPNET, select File / Model files / Add theoretical account directory. Point to your freshly created directory and take do this the default directory.

3. Lab 1: Hidden Node Scenario

Methodology

Run a simulation on a radio LAN ( WLAN ) scenario, which suffers from “ concealed node ” job

Detect the consequence of the job utilizing the gathered statistics

Enable the RTS/CTS characteristic to get the better of this issue

Verify that the web public presentation improves as a consequence of enabling the RTS/CTS frame exchange

Start OPNET Modeler

Open undertaking “ 1332_WLAN ” .

Select File / Open.

Select Project.

Choose “ 1332_WLAN ” .

Click OK.

Observe traffic scenes

Right-click on Node B.

Select Edit Attributes.

Observe the inter-arrival clip parametric quantities

Expand Traffic Generation Parameters.

Observe the scenes.

Observe the package size parametric quantities

Expand Packet Generation Arguments.

Observe the scenes.

Click Cancel.

Run simulation

Click on the Configure/Run Discrete Event Simulation ( DES ) button.

Notice that the simulation Duration is 1000 seconds.

Click Run.

When the simulation completes, snap the Close button.

View node motion and consequences

Click on the Hide/Show Graph Panels button.

Select DES / Panel Operations / Panel Templates / Load with Latest Results.

Observe the consequences shown.

Move the consequence panels around, and do them smaller if necessary, so that you can see both the consequences and the nodes in the web.

Select View / Show Time Controller.

Time Controller is a new characteristic that can be used to see how web informations, like location of a nomadic node that is traveling along its flight or a consequence panel that shows a time-varying statistic, alterations over clip.

Click on Configureaˆ¦ button.

Set the value of Slider terminal clip to 1000s and snap on OK.

Note that this was besides the continuance of our simulation tally.

On Time Controller window chink on & gt ; & gt ; to progress the life with 1-minute stairss.

Observe that, with each measure, the green perpendicular bars on consequences panels traveling to the right and the nomadic node is tracking its flight ( e.g. , traveling between proceedingss 5 and 12 ) .

Consequences analysis

At 350 seconds, Node A becomes a concealed node to Node B ( and frailty versa ) for about 300 seconds due to the defined flight form.

During this period, since Node A and Node B ca n’t observe each other ‘s transmittals, the hit chance for their transmittals additions.

Increased hits chance leads to higher figure of hits and retransmissions.

Wireless LAN hold additions due to packet loss and retransmissions.

Expected throughput is achieved merely through a high figure of retransmissions.

Close Time Controller window and snap the Hide/Show Graph Panels button to conceal the graphs.

Using RTS/CTS mechanism

Switch scenarios

Choice Scenarios / Switch to Scenario.

Select “ hidden_node_rts_cts ” scenario.

Select all WLAN Stationss

Right-click on any station.

Choose Select Similar Nodes.

Edit node properties

Right-click on any of the selected Stationss.

Select Edit Attributes.

Click Apply alterations to Selected Objects.

Expand the property Wireless LAN / Wireless LAN Parameters.

Click on the value field of RTS Threshold ( bytes ) .

Select Editaˆ¦

Enter 1024.

Recall that the minimal size of the generated packages is 1500 bytes.

Close both attribute redacting Windowss by snaping on OK.

Type Ctrl+S to salvage the undertaking.

Run simulation

Click on the Configure/Run Discrete Event Simulation ( DES ) button.

Notice that the simulation Duration is 1000 seconds.

Click Run.

When the simulation completes click on Close button.

Position consequences

Click the Hide/Show Graph Panels button.

Select DES / Panel Operations / Panel Templates / Load with Latest Results.

The panels will be updated with the latest consequences.

Like we did in the first portion of the lab, experience free to analyze the consequences besides by utilizing Time Controller.

Consequences analysis

At 350 seconds, Node A becomes a concealed node to Node B ( and frailty versa ) for about 300 seconds.

During this period, usage of RTS/CTS frame exchange reduces the figure of hits ( and hence retransmissions ) significantly.

CTS message sent by the Receiver node informs the transmitter nodes about the approaching informations transmittal effort of the other node and its reserve of the channel.

There are still more transmittals compared to when Node A and Node B can observe each other ‘s transmittals, because they sense the on-going activity on the medium still merely when the Receiver responses to the other transmitter ‘s RTS with a CTS.

Due to less figure of retransmissions, the radio LAN hold drops drastically for the period when the nodes are hidden to each other.

The hold when Node A and B can hear each other is now higher because of the operating expense caused by the RTS/CTS exchanges.

Click the Hide/Show Graph Panels button to conceal the graphs.

Type Ctrl+S to salvage the undertaking.

4. Lab 2: Infrastructure ESS ( Extended Service Set )

Methodology

Create an independent BSS radio LAN web that spans multiple floors on a edifice

Configure appropriate properties and so run a simulation

Analyze the statistics to detect that the web public presentation is non satisfactory

Add more entree points to construct an ESS web

Restrict the figure of entree points as 3 to forestall channel imbrication, therefore no intervention

Run another simulation to happen out whether the extra entree points better the web public presentation

Instruction manuals

Switch to the Infastructure_BSS scenario

Select Scenario / Switch to scenario.

Select “ Infastructure_BSS ” .

Completing the web

Open the object pallet

Click on the Open Object Palette button.

Add 3 wireless workstations to each degree

Click on the wlan_wkstn ( hole ) node inside the object pallet.

Place nine workstations to the undertaking workspace as shown on the undermentioned figure.

When done, right-click in the workspace to stop object creative activity.

Near the object pallet window

Configuring the workstations

Select all WLAN Stationss

Right-click on any station.

Choose Select Similar Nodes.

Configure traffic

Right-click on any of the selected Stationss.

Select Edit Attributes.

Check the box Apply alterations to selected objects.

Expand the property Applications / Application: Supported Profiles.

Add one row by puting row value to 1.

Expand this new row.

Set Profile Name to Wlan_engineer.

Set WLAN data rate to 1 Mbps

Expand the property Wireless LAN / Wireless LAN Parameters.

Set Data Rate to 1 Mbps.

Click OK to salvage attribute value alterations.

Click on the workspace to deselect the nodes.

Choosing the statistics for aggregation

Observe selected statistics

Right-click in an empty country of the workspace and select Choose Individual DES Statistics.

Expand Global Statistics.

Observe statistics chosen

Electronic mail

File transfer protocol

Hypertext transfer protocol

Remote Login

Wireless LAN

Click Cancel.

Runing simulation and screening consequences

Run simulation

Salvage the undertaking by typing Ctrl+S.

Click on the Configure/Run Discrete Event Simulation ( DES ) button.

Notice that the simulation Duration is 10 proceedingss.

Click on Run button.

When the simulation completes click on Close button.

Position consequences

Click the Hide/Show Graph Panels button.

Select DES / Panel Operations / Panel Templates / Load with the Latest Results.

The panels will be updated with the latest consequences.

Consequences may be different due to node positioning! To acquire the matching consequences, use the mention undertaking.

Consequences analysis

High application response clip

Application informations received is lower than the application burden

Wireless LAN entree is really high and remains high

The web is saturated ; WLAN MACs bead packages because their buffers are congested and full

Click the Hide/Show Graph Panels button to conceal the graphs.

Type Ctrl+S to salvage the undertaking.

Scaling capacity by aggregating bandwidth

Adding new entree points

Duplicate scenario

Choice Scenarios / Duplicate Scenario.

Type “ Infrastructure_ESS ” .

Click OK.

Create new entree points for degree 3 and 4

Choose the entree point node at degree 2 ( AP_Level_2 ) by snaping on it.

Press Ctrl+C or choose Edit / Copy.

Press Ctrl+V or choose Edit / Paste.

Click on an country on degree 3.

Click on the Switch node to link the nexus from the entree point.

Repeat above stairss to make the web as shown below.

Configuring each entree point

Edit the properties of the entree point on degree 2 ( AP_level_2 )

Right-click on the entree point node AP_level_2.

Select Edit Attributes.

Expand Wireless LAN / Wireless LAN Parameters.

Set the value of the BSS Identifier to the degree figure ( 2 for degree 2, 3 for degree 3, aˆ¦ ) .

Click OK.

Click in the workspace to deselect the node.

Edit the properties of the entree points on degree 3 and 4

Repeat the old stairss for entree points on degrees 3 and 4.

Configuring the workstations

Configure all WLAN workstations on degree 2

Click on each node while keeping down Shift key.

Do non choose the entree points or the switch!

Right-click on any of the selected Stationss.

Select Edit Attributes.

Check the Apply alterations to Selected Objects box.

Expand Wireless LAN / Wireless LAN Parameters.

Set the value of the BSS Identifier to the degree figure ( 2 for degree 2, 3 for degree 3, aˆ¦ ) .

Click OK.

Click in the workspace to deselect the nodes.

Configure the workstations on degree 3 and 4

Repeat the old stairss for workstations on degrees 3 and 4.

Runing simulation and screening consequences

Run simulation

Type Ctrl+S to salvage the undertaking.

Click on the Configure/Run Discrete Event Simulation ( DES ) button.

Notice that the simulation Duration is 10 proceedingss.

Click Run.

When the simulation completes click on Close button.

Import an analysis constellation file to compare consequences

Menu: Scenarios / Scenario Components / Importaˆ¦ / Analysis Configuration.

Select “ 1332_infrastructure_ess ” .

Choose Yes to destruct the bing panels.

Select DES / Panel Operations / Panel Templates / Load with Latest Results.

The panels will be updated with the latest consequences.

Consequences may be different due to the place of nodes!

Consequences analysis

Deployment of extra entree points increased the WLAN capacity

Sharing the clients among the entree points reduced the contention for each shared medium

No WLAN package beads are observed any longer

Application throughput increased significantly

Lower WLAN detain due to less contention lowered besides application end-to-end hold despite higher throughput

Increasing the figure of hit spheres is an utile option when the information rate can non be increased

Click the Hide/Show Graph Panels button to conceal the graphs.

Type Ctrl+S to salvage the undertaking.

5. Report

Your study should include:

A description of your methods.

An illustration of an OPNET study file.

All derived throughput-load diagrams.

A short reading for each diagram.

A comparative analysis of theory and simulation.

Decisions.