Although I searched the ns-users list on this subject, I could not find a satisfactory answer. I am wondering why ns 802.11 MAC code guesses RTS/CTS and Data retransmission timeouts as are? For example retransmission timeout for RTS packets is calculated as: timeout = txtime(phymib_.getRTSlen(), basicRate_) + DSSS_MaxPropagationDelay + sifs_ + txtime(phymib_.getCTSlen(), basicRate_) + DSSS_MaxPropagationDelay; If we assume RTS packets have been in collision, the transmitter may figure out a collision has occurred if no other transmission starts at the slot after SIFS (CTS transmission should have been started). So timeout can be (this approach can save considerable bandwidth in some scenarios): timeout = txtime(phymib_.getRTSlen(), basicRate_) + DSSS_MaxPropagationDelay + sifs_ + 1 slot. A similar discussion holds for data timeout. So, I wonder about the reasoning behind the guess of the 802.11 ns MAC code. I'll appreciate any help/answer. I'm including a paragraph from 802.11 document if it may help. But Ack-timeout value is not specified anywhere in the document. Best regards, Inanc Inan ------------------------------------------------------------------------ ---- After transmitting an MPDU that requires an ACK frame as a response (see 9.7), the STA shall wait for an ACKTimeout interval, starting at the PHY- TXEND.confirm. If a PHY-RXSTART.indication does not occur during the ACKTimeout interval, the STA concludes that the transmission of the MPDU has failed, and this STA shall invoke its backoff procedure upon expiration of the ACKTimeout interval. If a PHY-RXSTART.indication does occur during the ACKTimeout interval, the STA shall wait for the corresponding PHY-RXEND.indication to determine whether the MPDU transmission was successful. The recognition of a valid ACK frame sent by the recipient of the MPDU requiring acknowledgment, corresponding to this PHY-RXEND.indication, shall be interpreted as successful acknowledgment, permitting the frame sequence to continue, or to end without retries, as appropriate for the particular frame sequence in progress. The recognition of anything else, including any other valid frame, shall be interpreted as failure of the MPDU transmission. In this instance, the STA shall invoke its backoff procedure at the PHY-RXEND.indication and may process the received frame. The sole exception is that recognition of a valid data frame sent by the recipient of a PS-Poll frame shall also be accepted as successful acknowledgment of the PS-Poll frame.