Posts Tagged Bugs

IEEE802.11 implementation in MiXiM

Posted by on Friday, 9 September, 2011

In some of my simulation studies I use (a modified) Mac80211 implementation as present in MiXiM for OMNeT++. Sometimes it is sensible to represent 1k+ lines of code in a figure. Read the rest of this entry »

MiXiM 802.11 – is CSMA/CA implemented correctly?

Posted by on Friday, 15 July, 2011

I’ve spent some time comparing MiXiM simulation results with some
analytical work with IEEE802.11-2007 in hand, and I wonder if Mac80211 as implemented in MiXiM 2.1
contains an error. I have posted on the Google groups and made a bugreport, but no replies. I have a fix for this bug (see below). Read the rest of this entry »

Wrong duration of SlotTime in IEEE 802.11p in NS-2 / NS-3

Posted by on Wednesday, 20 April, 2011

IEEE 802.11p is designed for use in the V2V / V2I context. It uses an OFDM physical layer largely based on IEEE 802.11a. Some values are directly reused, others are modified. The slottime (often denoted with the Greek ‘sigma’ or aSlotTime) is one of those values which are unclear.

As a result, NS-2 and NS-3 erroneously use a wrong 802.11p slotTime of 13 microseconds. Scientific works using these simulators should carefully check sensitivity to this bug – results may be off!
Read the rest of this entry »