Hi, all According to the IEEE 802.11 MAC/PHY standard, a wireless station must perform carrier sensing for a time interval of DIFS + rTime, before it starts frame transmission. rTime is called as random backoff time and is given by the product of SlotTime and a random value which is chosen from [0,CW], where CW is the current contention window size.
But, in ns2 rTime is defined as follows (in 4 places): rTime = (Random::random() % cw_) * phymib_.getSlotTime(); (Please refer to tx_resume() and send(Packet *p, Handler *h) functions in mac-802_11.cc and start(int cw, int idle) function in mac-timers.cc) Therefore, in ns2 random value is chosen from [0,CW-1]. So, I think rTime should be defined as: rTime = (Random::random() % (cw_+1)) * phymib_.getSlotTime();. Am I correct? Comments concerning this are welcome. Thanks in advance. With regards, ************************************** B. A. Hirantha Sithira Abeysekera, Dept. of Communication Engineering, Graduate School of Engineering, Osaka University, Suita, 565-0871, Japan Tel: +81-6-6879-7742 [EMAIL PROTECTED] **************************************
