Wireless Network Simulation

University of Aden Faculty of Engineering Department of Computer Science & Engineering

2009 Wireless Network Simulation

Using OPNET IT Guru Academic Edition. Name: Mohammed Abdullah Al-Rudaini. Class: B5CS RegNO: 7794 Supervisor: Dr- Khaled Obood.

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Introduction:

1.1. What is an OPNET IT Guru: OPNET IT Guru Academic Edition provides a virtual environment for modeling, analyzing, and predicting the performance of IT infrastructures, including applications, servers, and networking technologies. Based on OPNET's award-winning IT Guru product, Academic Edition is designed to complement specific lab exercises that teach fundamental networking concepts. The commercial version of IT Guru has broader capabilities designed for the enterprise IT environment, documentation, and professional support. OPNET software is used by thousands of commercial and government organizations worldwide, and by over 500 universities. 1.2. OPNET IT Guru wireless capabilities: As for the OPNET Modeler designed by OPNET Technologies is the first program in the area of telecommunications networks in general, not only at the level of computer networks only. Program has great potential in many areas and is the most widely used of all universities in the world for the purposes of scientific research. As we previously stated in the free software, free version available for purposes of scientific research but is limited when compared with the commercial version. Especially for wireless computer networks, the OPNET IT Guru Academic Edition (free version), the maximum possible to work on wireless networks is the IEEE 802.11b standard only! This version does not support the use of networks of free WiMax. Also, there are limitations in many of the options and possibilities in the free version when compared with the commercial version, including the time of simulation. The free version and it is known as OPNET IT Guru is a great competitor to the ns-2 which is designed to work on the systems of Linux.

1.3. Purposes of the simulation of computer networks: Two basic goals of the use of simulation programs are: The First: scientific research, for example, the study of global IEEE Standards for wireless computer networks and ways of development and everything related to The Second: for commercial purposes, as mentioned earlier, that if we want changes to be made to our real networks, changes are expensive, and simple mistakes that could lead to high costs, so it is possible to study the implementation of the network even before it is implemented on the ground.

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1.4. Introduction to Network Simulation: Network simulators attempt to model real world networks. The idea being that if a system can be modeled, then features of the model can be changed and the results analyzed. As the process of model modification is relatively cheap then a wide variety of scenarios can be analyzed at low cost relative to making changes to a real network. Note: Network simulators are not perfect. They will not perfectly model your network. They will, however, be close enough so as to give you a meaningful insight into how your network is working, and how changes will affect its operation. The following figure shows the simulation cycle of any type of computer networks, this is known as the four stages of The Modeling Cycle.

In the first phase, we are modeling the network, and the process here involves the addition of computers, wiring, servers, etc. ... If we are talking about a wireless WLAN network may choose at this stage, the type of global standard IEEE 802.11b, IEEE 802.11a, IEEE 802.11g and choose the type of Modulation Method, etc. In the second phase, we will choose the statistics. Statistics collected on the performance of the network as mentioned earlier. In the third phase, we the simulation set up Simulate time that we want to emulate the network by. Simulation time means that, for example, if the simulation program was run on the basis of one day, all the results we get are the modeling of the network for one day on the ground, the operation of the network on the ground for a one-day operation may be offset by the simulation program for five minutes! Imagine the difference. Fourth and final stage, is the view the simulation results and we will do our part to analyze them. 3

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Wireless Infrastructure:

2.1. Wireless network refers to any type of computer network that is wireless, and is commonly associated with a telecommunications network whose interconnections between nodes is implemented without the use of wires. Wireless telecommunications networks are generally implemented with some type of remote information transmission system that uses electromagnetic waves, such as radio waves, for the carrier and this implementation usually takes place at the physical level or "layer" of the network. 2.1.1. Wireless Personal Area Network (WPAN) is a type of wireless network that interconnects devices within a relatively small area, generally within reach of a person. For example, Bluetooth provides a WPAN for interconnecting a headset to a laptop. ZigBee also supports WPAN applications. 2.1.2. Wireless Local Area Network (WLAN) is a wireless alternative to a computer Local Area Network (LAN) that uses radio instead of wires to transmit data back and forth between computers in a small area such as a home, office, or school. Wireless LANs are standardized under the IEEE 802.11 series. 2.1.3. Wireless Metropolitan area networks(WMAN)are a type of wireless network that connects several Wireless LANs. WiMAX is the term used to refer to wireless MANs and is covered in IEEE 802.16d/802.16e. 2.2. Wireless network Scenario: In this case study we will create we will create four scenarios of a wireless network for an office of 20 employee starting with the simple standard IEEE802.11that its data transfer rate operates on 1& 2 Mbps and then we will go up till reach the standard IEEE802.11b that its data transfer rate operates on 11Mbps. The scenarios will be used to provide an internet connection to use HTTP protocol to work on the main website of the company to enter the data into it by the employees working into that office and so to search about work data that is inside it. Then we will compare the four scenarios to find the best one to choose in the real work.

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2.2.1. Building Scenario: To start building our scenario infrastructure we run to OPNET IT GURU simulation, we will start with one scenario then we will duplicate it and re configure them to build the other scenarios. After starting the program, we will create a new project from the “new” option in the “file” menu as follows. Then name the project and the first scenario as follows. After that the initial topology must be chosen for our scenario we will start with an empty one. Then indicating the type of network scale, so as mentioned before, an office scale will be chosen for our scenario.

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After that we will come to indicating the size of the office using a measure scale as meters and the units of that metric as 100 by 100 office as it a big floor of a large company. After that the configuration of the topologies and the tools which we want to use in our scenario that is the Ethernet for using normal LAN tools and Wireless LAN for using wireless tools in our scenario. At the end a review window will appear to review our selected main properties of our scenario.

When done a project workspace and an object palette will appear to start build our real infrastructure of our scenario. 6

We will start to but our main nodes manually in the scenario, using the object palette we but an Application Configuration Tool that will help us to configure the applications that will be used in the scenario, a Profile Configuration Tool that will help us to configure our user profiles and what application they supposed to use, an Ethernet Server that we provide application to be used in the WLAN, and finally Wireless LAN And Ethernet IP Router that will be used as an access point in our WLAN scenario. The second way to enter wanted nodes is using rabid configuration for nudes that are similar, by using the rabid configuration option in the topology menu, then selecting the configuration type as unconnected network from the small window that appears

At the end of butting the nodes used in our scenario we can connect any wired objects using a connection type, we choose a 100BaseT 7

connection from the object palette to connect between the server and the access point, and as for any node we can rename any node.

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2.2.2. Configuring Scenario: Then we start configure our nodes by right clicking the wanted node and then choosing edit attributes.  The application configuration tool will be configured to get the default application definition.  Then editing the profile configuration of profile configuration tool another window will appear to edit it, selecting the rows, where each row means a configuration entry, naming every entry and then edit their applications, also another window appears to select applications for that entry by selecting rows, here each row means an application entry, so here we can select a web browsing application that is our need in our scenario.

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 Selecting all the wireless workstations to be configured all together, editing the application supported profiles will open another window that we will select application rows and application types using it from the application profiles that we create using the application profile configuration tool, changing the value of physical characteristics attribute to the value of direct sequence, and finally changing the data rate to 1Mbps, this is the attribute that we will study the changes in scenario statistics by its variation

 The access point router will be enabled, and will set the data rate to 1Mbps as the same as the workstations. 10

 The server will be configured to support all application services.

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2.2.3. Selecting the statistics of the scenario: Now we should select the statistics that we will study in comparing scenarios by right clicking on any empty space in the workspace and choosing the individual statistics option,from the global statistics tree we will select the HTTP Page Response Time, TCP Delay, Wireless LANData Dropped, Wireless LANDelay, Wireless LANLoad, Wireless LANMedia Access Delay, and finally Wireless LANThroughput.

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2.2.4. Duplicating Scenarios: Duplicating the first scenario will help us to make a new one, naming it, and then changing some attribute in some nudes of the wireless network that we want to compare their effect on statistics and results upon the network, in our scenario we will change the data bit rate between the wireless access point and the wireless workstations, using four different values of data bit rate of 1Mbps as done in the first scenario, 2Mbps, 5.5Mbps, and 11Mbps that is the standard IEEE802.11b.

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2.2.5. Running Simulation: Now we have four different scenarios that can be switch between to run simulation on each one separately by choosing the run tool from the tool bar, selecting the simulation time (up to 8 hours for OPNET IT Guru Academic Edition free version).

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2.2.6. View Results: After running simulation for all scenarios we can now view results to compare between the scenarios by clicking on the show results tool on the tool bar, a view results window will appear showing all the selected statistics, selecting the overloaded statistics for all scenarios to be in the same graph with different colors, changing the view to the average type so the graph be in a curve way, finally we can view the graph in a separate window with full information and legend.  The HTTP page response time: from this graph comparing our four scenarios we understand that the response time of a HTTP page decreases as the data rate increases.

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 TCP Delay: as we do before the average TCP Delay graph shows that the average TCP delay decreases as the data rate increases.

 Wireless LAN Data Dropped: for all the scenarios this graph shows that the Wireless Data dropped tends to be zero.

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 Wireless LAN delay: this graph shows that the delay of the wireless LAN decreases as the data rate increases.

 Wireless LAN Load: the average load of the network will remain the same as the application supported and the number of the workstations stills the same.

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 Wireless LAN Media Access Delay: this graph shows that the media access delay will be decreased as the data rate increased.

 Wireless LAN Throughput: even if this graph is not seen the average throughput will be the same as the average load if the data dropped tend to zero (Load Request = Throughput Success + Data Dropped Failure), so here the graph tells us the same fact the throughput remains the same for all scenarios and looks like the load graph.

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