I am working on a masters [paper][1] where I am trying to change the random
waiting time for MAC wireless networks to a Period-controlled MAC for
higher performance. There are a couple of existing c++ files that need
alterations to change them from random to periodic. I have narrowed it
down to the following function:
void
BackoffTimer::start(int cw, int idle, double difs)
{
Scheduler &s = Scheduler::instance();
assert(busy_ == 0);
busy_ = 1;
paused_ = 0;
stime = s.clock();
rtime = (Random::random() % cw) * mac->phymib_.getSlotTime();
#ifdef USE_SLOT_TIME
ROUND_TIME();
#endif
difs_wait = difs;
if(idle == 0)
paused_ = 1;
else {
assert(rtime + difs_wait >= 0.0);
s.schedule(this, &intr, rtime + difs_wait);
}
}
I would appreciate it if anyone could help me alter this method to change
the random calculation to periodic. Thanks.
I will explain the proposed protocol in terms of a simple scenario:
consider 2 transmitting nodes experiencing a collision in a network; after
they each have waited a random amount of time; say x and y, (implying they
both have different backoff periods) if we imply periodic backoff from
there on, their backoffs will be x+a, y+a which goes on and will never be
equal; preventing them from ever colliding with each other again.
Also, the period of the backoff is same for all the nodes in the network
('a' in the above example), and any change that has to be done with this
'a' period will also affect with all the nodes in the network.
rtime in the program denotes the remaining time of backoff,
cw denotes the contention window value and
difs denotes the 802.11 dcf inter frame space
Any advice or suggestion will be much appreciated.
