Re: [ns] mac-802_11.cc ACKTimeout looks incorrect & sifs/difs used incorectly?

["Jun Zhao" <JZhao_NS@hotmail.com>]

I am concerned about the same problem.

But I did not find out the specs. about ACK timeout in the 1999 version. Can
you give me the ref.?
----- Original Message -----
From: "Susan Tsao" <SusanTsao@WoodsideNet.Com>
To: "Ns-Users (E-mail)" <ns-users@ISI.EDU>
Sent: Saturday, October 06, 2001 8:05 AM
Subject: [ns] mac-802_11.cc ACKTimeout looks incorrect & sifs/difs used
incorectly?


> Hello,
>
> I have 2 quesiton relating to NS implementation of the Mac 802.11
> protocol.
>
> 1) In mac-802_11.h, it defines ACKTimeout to be:
>
> #define ACKTimeout(len) (DATA_Time(len) + ACK_Time + sifs_ +
> difs_)
>
>     But according to standard, it should be:
> #define ACKTimeout(len) (DATA_Time(len) + ACK_Time + sifs_ +
> sifs_)
>
> 2) In mac-802_11.cc:
>
> void Mac802_11::tx_resume()
> {
>       .........
>     else if(pktTx_) {
>                if(mhBackoff_.busy() == 0)
>                         mhDefer_.start(difs_);
>    .........
> }
>
> According to standards:  Upon receiving a CTS frame, station will wait
> for SIFS period before sending DATA
> However, according to the above code, station waits for DIFS period
> before sending DATA.
> Can someone please explain to me whether this is a bug in the code or
> did I misinterpret the standard.
> Thank you.
> Susan
>
>