Officially the topic is “Radio Resource Management for Quality of Service in Heterogeneous Wireless Networks”. This is quite the mouthful, I know. Really what it boils down to is: Making various wireless technologies (Bluetooth, WiFi, WiMAX, 3G, 4G, … , etc) seamlessly work together. Many devices are capable of connecting to many of these radio access technologies (RATs), but often it is not seamless. What do I mean by this? Well suppose I am inside a university building, deep in the basement (where they tend to put CS students ) where there is no mobile reception (3G, 4G etc.). I start downloading a large file, or call someone via wifi. Now I want to walk to my car because it’s time to go home for the day. Many networks now are not able to handle this, and it is interrupted after you change networks. Furthermore, you often have to manually tell the device you want to leave one network and join another. Seamless means this should all happen without you noticing. This is the focus of my research.

The biggest problem that I am concerned with is called handoff or handover. This is when the switch between RATs occurs. Traditionally, this also occurs when a mobile device switches from one tower to another, and it usually involved predicting the motion of the device along with some other factors for Quality of Service (QoS). For a vertical handover, we may or may not need to predict motion. If the heterogeneous wireless network (HWN) is densely covered, many RATs are available throughout the coverage region (as opposed to a sparsely covered where a given location may have access to one technology at once). In a dense HWN, the problem becomes a multi-criteria question.

1. Which network is most economical for me to connect to?
2. Which configuration of (network, client) pairs is most profitable for the operator?
3. Which network is able to provide me with the required QoS?

More technical details to follow…

Abstract:
In wireless networks, conditions may change rapidly and unpredictably. Often wireless networks are not designed to adapt to these changing conditions and perform poorly when they become congested. The multi-hop broadcast nature of wireless mesh networks amplifies the problem of poor wireless performance. Mixed bias scheduling has previously been applied successfully to wireless mesh networks however, it still suffers from similar problems when conditions change rapidly. In this work we propose an adaptive mixed bias (AMB) algorithm which uses a tabu search approach to change based on delay and dropped packets in the network. The proposed scheduling approach consists of three important algorithms, namely, the tabu search algorithm, move generation, and utility function. The adaptive mixed bias approach is compared against IEEE 802.11 and the non-adaptive mixed bias approach. The performance is evaluated using the packet delivery ratio and average end-to-end delay metrics.

Here are the slides from the talk: BWCCA-NGWMN2010-final (pdf)
and here is the link to the pdf from the conference: Adaptive Mixed Bias Resource Allocation for Wireless Mesh Networks (pfd)

Here are some pictures from the day:

Preparing for the Defense before Everyone Arrives

Some Members of Pervasive Computing and Wireless Network (PerWin) Research Group, University of Guelph

Answering Questions from the Committee at Guelph

After some relaxing, a conference in UK and some business related projects I will finally have some time (hopefully) to update the site with all the projects, articles and source I have been slowly working on the past few months in between working like crazy on my M.Sc. This fall I start my Ph.D. which will likely at least start from the work I just worked on.

Today I completed the listing page for all of the presentations our research group PerWin at the University of Guelph has made in the last year or so. PerWin stands for Pervasive Computing and Wireless Networking Research. The group is directed by my advisor, Dr. Mieso Denko and has several graduate students who are active research members in the group. We have given presentations on topics ranging from Wireless Mesh Networks protocols, Autonomous networks, Fair Scheduling, Load Balancing, RFID, Wireless Security and much more. We have also had special invited talks by several faculty members from various Universities around Ontario (Ryerson, UOIT).

Reynolds Building @ University of Guelph where PerWin meets regularly

Check out the schedule page here for the list of presentations, presenters and topics. There are also listings of many of the websites for the presenters which may be a good resource for people interested in our work. If you are a faculty member interested in giving a talk contact Dr. Mieso Denko at the University of Guelph.

If you are interested in any of the talks I have given, all of the powerpoint presentations are available at my Academic Website at the University of Guelph.

I have found many people already who have had difficulty setting it up so maybe this will be of some help to someone. For this tutorial I am assuming you have installed the most recent version of Ubuntu (8.04). (At the time of writing)

Step 1: Update Ubuntu

Since it has already been a month or so since Hardy Heron has been released its probably best, if you haven’t already done so to update Ubuntu. The easiest way I’ve found is to go to System>>Administration>>Update Manager. Alternatively, you can enter this into the terminal:

sudo apt-get update
sudo apt-get upgrade

Step 2: Download all of the required pieces to make ns2 work

Here is a list of archives required for ns2 to work properly (you can download them by clicking the links or just enter all of the commands in the code sections below for automatic download and untar). I saved each archive to the desktop so I could find each one easily but you could use anywhere you like.

1. tcl 8.4.14
2. tk 8.4.14
3. otcl 1.13
4. tclcl 1.19
5. ns 2.33
6. nam 1.13

Step 2.5: Install Ubuntu Packages

Before installing everything else, I have found that it is helpful to get a few packages from the ubuntu repositories or else it wont build correctly. Grab a cup of coffee it might take a while since kdebase-dev is somewhat large. I’m sure there is a way to do this with fewer packages however I know this works. If anyone figures out exactly which packages are required let me know so I can update this.

Step 3: Install tcl

wget http://www.jasonernst.com/wp-content/uploads/2008/06/tcl8.4.19-src.tar.gz
tar xvf tcl8.4.19-src.tar.gz
cd tcl8.4.19/unix
./configure
make
sudo make install

Step 4: Install tk

cd ..
cd ..
wget http://www.jasonernst.com/wp-content/uploads/2008/06/tk8.4.19-src.tar.gz
tar xvf tk8.4.19-src.tar.gz
cd tk8.4.19/unix
./configure
make
sudo make install

Step 5: Install oTcl

Important Note: The ‘./configure –with-tcl=’ portion of the following two code fragments should point to the source files for tcl. If you have been following the guide by copying and pasting the previous commands what we have here will work just fine. Otherwise you will need to change this to point to the correct location of your tcl source files.

cd ..
cd ..
wget http://www.jasonernst.com/wp-content/uploads/2008/06/otcl-src-1.13.tar.gz
tar xvf otcl-src-1.13.tar.gz
cd otcl-1.13
./configure --with-tcl=../tcl*/
make
sudo make install

Step 6: Install tclcl

cd ..
wget http://www.jasonernst.com/wp-content/uploads/2008/06/tclcl-src-1.19.tar.gz
tar xvf tclcl-src-1.19.tar.gz
cd tclcl-1.19
./configure --with-tcl=../tcl*/
make
sudo make install

Step 7: Install ns2

cd ..
wget http://www.jasonernst.com/wp-content/uploads/2008/06/ns-2.33.tar.gz
tar xvf ns-2.33.tar.gz
cd ns-2.33
./configure
make
sudo make install

You will likely get alot of warnings for deprecated conversions. Just ignore these or if you really are concerned about them visit the nsnam troubleshooting page. If you want to make sure your version of ns-2 is working correctly after the install you can run the validation test from within the ns2 source directory. You can do this by entering:

You should see that the test output agrees with the reference output. Congratulations you have a working version of ns-2 installed.

Step 8: (optional) Install nam

cd ..
wget http://www.jasonernst.com/wp-content/uploads/2008/06/nam-src-1.13.tar.gz
tar xvf nam-src-1.13.tar.gz
cd nam-1.13
./configure
make
sudo make install

Note: if you get this error:

it may be necesary to do this:

You are now ready to start working with ns2 and nam. If you are like me and working on a new protocol or something you will want to start modifying the ns-2 source code and recompile again so you might want to keep that folder handy. The rest of the source can be safely removed as far as i know. Keep in mind after you have modified the source you will want to do another make install so that when you type ns in your terminal the version you just compiled is used.

Getting Started with NS2

These are some quick tips to get you started using ns2 if you are a beginner.

All example files are located in ns/tcl/ex. You can run these scenarios on ns2 using ns filename.tcl The best way to start is probably changing things in these files until you understand what is happening more thoroughly.

The output will usually be a trace file with a similar name: ex) filename.tr. Trace files can usually be viewed with a text-editor program. There are also tools to analyze the trace files and pull stats from them. These may require some tweaking however depending on the format of the trace file. Additionally, a nam output file for visualization may be generated as well. This will usually be named filename.nam. To view the visualization use: nam filename.nam

Useful Links

I thought it might be useful to add a section on useful links here since this article has become quite popular. If you would like to suggest a link feel free to contact me.

• Ns2 Wiki
• Marc Greis’ Tutorial
• NS Manual
• NS for Beginners (pdf)
• Common NS2 Installation Problems
• NS2 Wireless and Mobility Modules
• NS2 Mailing Lists
• NS2.33 Wireless MAC and PHY improvements