Hello,
I would like to use an implementation of 802.11a which can be found in file
"IEEE802-11a.tcl", under the directory:
.../ns-allinone-2.35/ns-2.35/tcl/ex/802.11
This implementation uses "Phy/WirelessPhyExt" and " Mac/802_11Ext" of ns2.
So, I read the documentation about 802.11a standard and also the code of
"Phy/WirelessPhyExt.cc".
As I understood in implemtation of "Phy/WirelessPhyExt.cc", there is no
"RXThreshold_" and there is a "CSThreshold_" which is only used to inform the
upper mac layer about the fact that the carrier is busy. But the decision to
keep or drop a packet is made roughly speaking by the below comparisons:
if (Pr(or received signal power) / noise_floor_ >=SNIR (of basic scheme) and if
(Pr(or received signal power) / noise_floor_ >=SNIR (of body modulation scheme)
then signal could be received.
Where basic scheme is a modulation scheme used for the header and the body
scheme id the modulation scheme used for the body and which both by default are
BPSK modulation with 1/2 coding rate.
So I have two questions:
1) By default in "IEEE802-11a.tcl", the value of "noise_floor_ " is 2.512e-13
which corresponds to -96 dBm for 10MHz bandwidth. I could not find how this
value is set. Since, I could not find something which corresponds to the noise
floor in the official documentation of 802.11a. Also, since 802.11a channel
bandwidth is 20Mhz; should not we increase this value?
2) Is there a way in this model (i.e., "Phy/WirelessPhyExt" and "
Mac/802_11Ext" ), to define the transmission range for a node? I guess it
should be independent of CSThreshold_.
Thanks in advance for your time and consideration,
Behnaz
