Tuesday, April 1, 2008

get a reference to node at MAC layer

The mac layer itself does not have a data or function member to return the node object. However, it has an reference to its physical interface, which can access the node object. My code to access node object in mac-802_11.cc is


Powered by ScribeFire.

get a reference to node at wireless physical layer

Both Class wirelessPhy and Phy provide a function to access its protected member node_, which refers to its node object. For example, if one wants to know the node id in the physical layer, use the following command:

node()->nodeid(), which returns an integer.

Powered by ScribeFire.

ns-2.33 added new mac models

Today, a new version of ns (2.33) has been announced. Several new 802.11 models has been added into this version, which is an exciting news. Here is a summary of these new models:

  • 802.11 infrastructure extensions:
Support AP, and inter-AP communications, and handoff. (http://ee.washington.edu/research/funlab/802_11/report_80211_IM.pdf)

  • 802.11 Ext
Mercedes-Benz R&D contributed to this model (I am surprised to know Mercededes-Benz is also interested in network simulation). Neat function structure design, more accurate SINR computation, physical layer tracing, Nakagami fading model. In short, it should be a better choice for general 802.11 simulation. The ns doc says "The model should be used as a replacement for the existing models". (http://dsn.tm.uni-karlsruhe.de/Overhaul_NS-2.php)

  • dei802.11 mr
Multirate 802.11 module. Users are now supposed to be able to use different transmission rates, modulation and coding schemes. There's no RxThresh and CSThresh in this model. The packet reception is determined by a pre-defined PER-SINR curve. Users with such curve will be happy to use this model. (http://www.dei.unipd.it/%7Ebaldo/nsmiracle-dei80211mr-howto.html).

Also, from version 2.33, ns2 supports dynamical library, which means users don't need to touch the core source of ns to implement their own models. Cheers!

The original description of 802.11 from ns doc can be found from http://www.isi.edu/nsnam/ns/doc/node193.html#sec:802_11

Powered by ScribeFire.