A bound on the capacity of backoff and acknowledgment-based protocols

We study contention-resolution protocols for multiple-access channels. We show that every backoff protocol is transient if the arrival rate, lambda, is at least 0.42 and that the capacity of every backoff protocol is at most 0.42. Thus, we show that backoff protocols have (provably) smaller capacity than full-sensing protocols. Finally, we show that the corresponding results, with the larger arrival bound of 0.531, also hold for every acknowledgment-based protocol