In the case of an unsynchronized slot model for any given propagation delay, the aggregate system throughput S in IEEE 802.11 DCF networks can be calculated on the basis of TXSTA timing events. The events of successful data frame transmission are divided into events of successful TX-STA transmission and successful TX-STA reception.
The modified Bianchi’s analytical model evaluates the normalized value of the aggregate system throughput S as the fraction of time during which the channel is used to transmit data bits successfully.
Let Es denote the average length of variable length slot time, which consist of slots in which successful transmission occurs, slots in which collision occurs, and empty slots.