MAC Layer Queueing

[Don Tran]

Hello all,

I am an UG Researcher at Auburn University where I've been tasked with putting together a script(s) for simulating congestion control delay metrics in the MAC layer. I've read the brief set of rules about searching for topics before creating new posts, and have found no existing posts/messages which satisfy my needs--at least to the degree that will offset my lack of knowledge. I am VERY NEW to NS-3. I am also VERY NEW to Computer Networking concepts. I am a Software Engineer/CS student and have not yet had the pleasure of taking a Computer Networking course. I accepted this research position this Spring because I was led to believe all I would require was a firm grasp of C++. That couldn't have been further from the truth. Nevertheless, I dutifully accept challenges and learning new concepts. 

I have read the setup tutorial and have installed NS-3.26 on a Linux box running a version of CentOS. I have also built and compiled NS-3 onto that box. Since the box is a lab computer, I usually work remotely by SSH'ing into the school's network and working strictly from terminal. I plan to eventually install VMWare and Ubuntu onto a dedicated iMac which belongs to the research team. 

I will be attempting to simulate the data link layer via wireless network (WiFi) to evaluate congestion control, routing, and packet scheduling. I want to investigate low-latency multi-path coding and scheduling techniques subject to priority and deadline constraints. At this point in time, I would be happy with simply having a script that will allow me to facilitate/evaluate such a model using a single hop communication system for one-way traffic.

I'd like to kindly request some code which might help me gain a better understanding of the concepts I've attempted to relay. What would be even better is if I could find a soul who has the knowledge and patience to teach me things via Skype or otherwise. Upon developing a script, I'd also like some guidance on how I might visualize such a scenario (perhaps using NetAnim). I've looked at source code like "wifi-mac-queue.cc" and its related header files (source) to see how I might develop a script, but I'm afraid the documentation is very verbose and hard to understand. 

I apologize in advance if my comments, questions, and requests are not appropriate for this forum. I've perused through Stack Overflow and know how ruthless the coding community is, so I'm actually somewhat intimidated to be making a post like this. Any help would greatly be appreciated!

 

[Tommaso Pecorella]

Hi,

since you're so new to all these concepts, I'd start by studying the wifi model description.

It can be verbose, but you'll definitely need to understand it to go on.

The next step is to understand where the packets can be queued (it's the point where you can actually have some intelligent decision on scheduling and priority).

The hint is: there are some queues at MAC level and some others at TCP level.

The final step is to understand / figure out how to measure the queue occupancy (another hint: don't measure the queue size, check the packet's queueing delay) and do something fancy with it.

T.