[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_castWirelessPhyExt*(tifp)) {
   WirelessPhyExt *wifp = (WirelessPhyExt *)tifp;
   distCST_ = wifp-getDist(wifp-getPowerMonitorThresh(),
wifp-getPt(), wifp-getAntennaRxGain(), wifp-getAntennaTxGain(),
   highestZ , highestZ, wifp-getL(),
   wifp-getLambda());

[ns] CS_thresh in wireless-PhyExt of ns2.34 ( carrier sense threshhold)

[vitacai shun]

Hello everyone,

I find the default *CS_Thresh* is too large in  wireless-PhyExt  of ns2.34.

For example, the powerlevel() is 1.31 e-12, received  signal power  Pr is
1.06 e -12,
 hence SINR.ratio  = Pr/(powerlevel -Pr) = 4.2,

SINR.ratio  SINR_thresh （3.7）, so the signal can be decoded,  but
strangely,  the powerlevel  CS_thresh,
that is to say,  PHY will not send busyIndication to MAC layer.

This makes me confused, anyone can give some advice?

[ns] CSThresh_ in ns2.34 (wireless-phyExt.cc )

[vitacai shun]

-- Forwarded message --
From: vitacai shun vitacais...@gmail.com
Date: 2010/11/30
Subject: CSThresh_ in ns2.34 (wireless-phyExt.cc )
To: ns-users@isi.edu


Hi,

I want to tune the carrier sense range  to be close to transmission range ,
but  finding that  it has no effect . Anybody has tried ?

# default value :
#Phy/WirelessPhyExt set CSThresh_6.31e-12   ;

#change to:
Phy/WirelessPhyExt set CSThresh_50.31e-12

[ns] Little question about SIFS_Waiting state in 802.11Etx in ns2.34

[vitacai shun]

Hi, all

 I  encountered  a little question about SIFS_Waiting  state  in802.11
   DCF ,  while attemting to  learn   and extending  the
   802.11Ext implementation  for NS2.34.

   When a node(A) receives  a RTS frame,  it will  responds an CTS_1
   after aSIFStime if these no NAV,  which means  it is going to receive
   DATA . Is it possible that the node (A) transmit  another   frame
   during the SIFS?
   During  SIFS,   the Backoff,  channel state and NAC may all report
   OK to transmit. If another frame(F2) is transmit  by MAC after its
   SIFS, the PHY is  very likely still in Transmittin state for the first
   CTS_1,  which seems like  an  error for PHY.
   The reason I notice this question is,  that I am  desining an reliable
multicast_MAC extention for 802.11, which demands  the intended
   receivers to respends  CTS sequentially . So some receivers will wait
   longger time before transmitting  CTS,  and during this waiting time,
   any other transmission is not allowed logically. I use NAV to acheive
   this purpose, i.e. set NAV  =  wait_time.
   Any help will be appriciated.

   Regards,

   -Kara-

[ns] ExOR model for ns2

[vitacai shun]

Hi All，

Does any one can offer an ExOR(an Opportnistic routing protocol )
patch for ns2?

Any advice would be appreciated.

Sincerely，
Kara