Virtual carrier sensing (NAV) mechanism

Physical and virtual carrier-sense functions are used to determine the state of the medium. When either function indicates a busy medium, the medium shall be considered busy; otherwise, it shall be considered idle. This video is about the virtual carrier sensing mechanism. Virtual carrier sense mechanism is provided by the MAC layer and this mechanism is also called as Network Allocation Vector (NAV) mechanism. The NAV maintains the prediction of the traffic on the channel depending upon the value of duration field. The final decision of sending packet will depend upon the physical as well as virtual carrier sense mechanisms.

This video explains more about the working of NAV mechanism and talks about some rules needed to be followed to update the NAV field. Video also talks about the usage of the NAV field in hidden node problem.

Please download this file, before you view the presentation

Enable Javascript or Download Flash Playe if you see this!

This video series is a tutorial for IEEE 802.11 protocol suite, commonly knows as Wi-Fi. In this video series, you will find videos explaining the basic 802.11 standard and their other amendments like 802.11a, 802.11g, 80211h, 802.11i, 802.11w, 802.11n, 802.11e etc. There are videos dedicated to security in wifi protocols, the different packets and state machine of 802.11 protocol and many more such things. We have tried to make this video series more interactive than just informative. You will find lots of discussions over the issues in 802.11 and justification for many small features in 802.11. Feel free to pose your own problems in the comment section and we will try to capture them in next videos. This section is currently under construction, so keep watching for new content.

Amit Vartak, 27 is working in wired and wireless security fields since last 3-4 years. His current area of interest includes IEEE 802.11 (Wi-Fi) suite of protocols, vulnerabilities in these protocols and countermeasure for those vulnerabilities. Working on cutting edge tools and technology always keeps him busy. He has contributed from concept level to final prototyping for the presentations in Defcon 2007 (The Emperor Has No Cloak - WEP Cloaking Exposed) and Toorcon 2007 (Caffe latte attack). He holds 2 patents with USPTO (current status: Patent Pending) and a few papers in IEEE journals on wireless protocol vulnerabilities. Prior to this, he was working on MEMS (Micro Electro Mechanical Systems) and has published a few papers in SPIE and ICMAT. (Yeah… kindda orthogonal fields… but technology really doesn’t limit the talent :) He did his masters in Electrical Engineering from one of the premier institutes in India, Indian Institute of Technology, Bombay (IIT-Bombay) and his under graduation, from University of Mumbai in Electronics and Telecommunication Engineering. He is currently working with AirTight Networks Inc. as a team lead in technology group since last 3 years.You can get in touch with him at amitcv[at]gmail[dot]com