Date Added: Jul 2011
It is known that link throughputs of CSMA wireless networks can be computed from a time-reversible Markov chain arising from an Ideal CSMA Network model (ICN). In particular, this model yields general closed-form equations of link throughputs. However, an idealized and important assumption made in ICN is that the backoff countdown process is in "Continuous-time" and carrier sensing is instantaneous. As a result, there is no collision in ICN. In practical CSMA protocols such as IEEE 802.11, the stations count down in "Mini-timeslot" and the process is therefore a "Discrete-time" process. In particular, two stations may end their backoff process in the same mini-timeslot and then transmit simultaneously, resulting in a packet collision.