For each transmission MAC waits for its "ack" if ack did not receive on
time...it retransmit at time assigned by backoff time... in ns-2.34, MAC tries
7 times before declaring link break.
"
I don't know that why is the following highlight line used in *
Mac802_11::RetransmitDATA()* function?
"
It is the function responsible for that retransmission...I m talknig about
ns-2.34...I hope mechanism is similar for ns-2.35.
________________________________
From: M Falahati <md.falah...@gmail.com>
To: ns-users@ISI.EDU
Sent: Thursday, 6 December 2012 2:55 AM
Subject: [ns] Schedule the backoff timer in mac-802_11
Dear All,
I'm studying on implementation of mac-802_11 in ns-2.35.
I don't know that why is the following highlight line used in *
Mac802_11::RetransmitDATA()* function?
======================================================================
*if((u_int32_t)ETHER_ADDR(mh->dh_ra) == MAC_BROADCAST)
{
Packet::free(pktTx_);
pktTx_ = 0;
rst_cw();
mhBackoff_.start(cw_, is_idle());
return;
}*
======================================================================
I think that line runs following steps:
1- it invokes *BackoffTimer::start()* that because of *idle* parameter is
zero, then *pause*_ parameter will set to one.
2- *tx_resume()* in the *Mac802_11::send_timer()* invokes
*setTxState()*and changes
*tx_state* to *MAC_IDLE* , then invokes *checkBackoffTimer()*.
3- *checkBackoffTimer()* invokes *mhBackoff_.resume()* and backoff timer
will schedule with [0-CWMin] + DIFS value.
Are above steps true?
If answer is true,is it necessary to start backoff timer (with value
between [0-CWMin] + DIFS) after sending a broadcast packet?
Sincerely Yours.
