[ns] Why caculationof distCST_ changed in wirelessPhyExt (ns2.34)

[vitacai shun]

Hi,

I am still confused on  the carrier sense threshold.

1. CS_thresh
   CS_thresh is too large by default value (6.31e-12, 802.11a),  the
corresponding range is 168.3m , which equals to transmission range.


2. distCST_  is the carrier sensing range , but it is caculated according
to  powermonitorthresh,  ( )as in channel.cc:

Phy/WirelessPhyExt set PowerMonitorThresh_      1.259e-13
distCST_ = 447 m

 if (dynamic_cast<WirelessPhyExt*>(tifp)) {
           WirelessPhyExt *wifp = (WirelessPhyExt *)tifp;
           distCST_ = wifp->getDist(wifp->getPowerMonitorThresh(),
wifp->getPt(), wifp->getAntennaRxGain(), wifp->getAntennaTxGain(),
               highestZ , highestZ, wifp->getL(),
               wifp->getLambda());