On the cutoff point for pairwise enabling for infinite users in a multiaccess system

Consider a multiaccess channel shared by an infinite set of users, each of which, independently, has a message to transmit with probability p. Pairwise enabling is the scheduling algorithm which enables the users to transmit by pairs, and, if a collision occurs, it lets the two users transmit separately in the next two time slots. M.L. Molle (see ibid., vol.36, no.5, p.1127-33, 1990) showed that pairwise enabling is optimal for 0.5>