Re: [ns] Problem about the implemention of mac802_11

[Yun Li <liy_china@yahoo.com>]

A simple example is the "void send(Packet * p, Handler
 *h)" function in Mac-802_11.cc. In this
function,there 
are some statements like:
"
if(mhBackoff_.busy()==0) {
    if(is_idle()) {
       if(mhDefer_.busy()==0)
                mhDefer_.start(difs_);
     }
else {
     mhBackoff_.start(cw_.is_idle());
     }
}
"
    From these statements,we can conclude that when 
the media is busy, backoff a random time;else, defer
 difs_ time and send the packet. But the Mac802.11
 standard requires that even if the media is idle,the
 mac sender must backoff a random time. THIS IS THE
 FIRST CONFLICT that i can see.
   The second,we can't find where the physical layer's
CCA/CA function  which the standard requires was
implemented in ns-2.

 --- Jun Zhao <JZhao_NS@hotmail.com> wrote:
> Can you give us more detailed info? 
> ----- Original Message ----- 
> From: "Yun Li" <liy_china@yahoo.com>
> To: <ns-users@ISI.EDU>
> Cc: <ns-users@ISI.EDU>
> Sent: Tuesday, August 28, 2001 11:25 AM
> Subject: [ns] Problem about the implemention of
> mac802_11
> 
> 
> > Dear ns-users:
> > 
> > I have looked into the ns-2.1b8 resources code,
> > mAC-802_11.h and Mac-802_11.cc that implement the
> > MAC802.11 standard. I find that the implemention
> > doesn't follow the IEEE MAC802.11 standard. What's
> > your
> > opinion about this and am I right?
> >         Any idea will be appreciated!
> > 
> > __________________________________________________
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> > 


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