  We propose a contention-based random-access protocol, designed for wireless
networks where the number of users is not a priori known. The protocol operates
in rounds divided into equal-duration slots, performing at the same time
estimation of the number of users and resolution of their transmissions. The
users independently access the wireless link on a slot basis with a predefined
probability, resulting in a distribution of user transmissions over slots,
based on which the estimation and contention resolution are performed.
Specifically, the contention resolution is performed using successive
interference cancellation which, coupled with the use of the optimized access
probabilities, enables throughputs that are substantially higher than the
traditional slotted ALOHA-like protocols. The key feature of the proposed
protocol is that the round durations are not a priori set and they are
terminated when the estimation/contention-resolution performance reach the
satisfactory levels.
