16.3 802.11 MAC protocol

Prior to release ns-2.33, there was only one main-tree 802.11 model, although other researchers were maintaining third-party patches on the web. Starting with ns-2.33, there are multiple choices in the main distribution.

The first extension described below (infrastructure mode) extends the legacy model to include infrastructure mode. However, the last two items (802.11Ext and dei802mr) are complete replacements for the legacy model.

Therefore, researchers now have a choice of 802.11 models, and should carefully read the documentation and code of each one to understand which is the best fit for the job.

802.11 DCF from CMU
This model has been the only model available in the main ns source tree prior to release ns-2.33. See ~ns/mac-802_11.{cc,h} for implementation details. It uses a RTS/CTS/DATA/ACK pattern for all unicast packets and simply sends out DATA for all broadcast packets. The implementation uses both physical and virtual carrier sense. The Mac802_11../ns-2/mac-802_11.h is implemented in ~ns/mac-802_11.{cc,h}.
802.11 infrastructure extensions
Ilango Purushothaman from the University of Washington has implemented infrastructure extensions to the above 802.11 model, and fixed some bugs along the way. The extensions include passive and active scanning, authentication, association, inter-AP communications, and mobility support (handoff). Please note that this model still supports single-channel scenarios only.
A team from Mercedes-Benz Research and Development North America and from University of Karlsruhe have collaborated to develop a completely new 802.11 Mac and Phy model, called Mac802_11Ext and WirelessPhyExt, respectively. The new model contains the following features: This model should be used as a replacement for the existing models. The example scripts show how to do this.
The dei80211mr library - nicknamed 'multirate' for short - provides an 802.11 derived from the CMU implementation. This library depends on the Dynamic Library (Chapter 28) and is included in the ns-allinone distribution only (see the top-level dei80211mr directory in the ns-allinone distribution or see http://www.dei.unipd.it/wdyn/?IDsezione=5091). For step-by-step installation instructions, please refer to the tutorial at http://www.dei.unipd.it/%7Ebaldo/nsmiracle-dei80211mr-howto.html The following functionalities are provided by the dei80211mr library:

In addition, a patch (relating to the CMU implementation) improving ns-2 802.11 wireless support is available at http://www.telematica.polito.it/fiore/. The patch introduces realistic channel propagation, concurrent multiple data transmission rates among stations and ARF mechanisms, has been tested with ns-2.29, and features the following contributions:

Tom Henderson 2011-11-05