Apples and Oranges: Comparing Schedule- and Contention-based Medium Access Control

摘要

Comparison of schedule and contention based MAC protocols is made difficult by their fundamental differences in approach to medium access control. This paper provides a way in which to analyze and compare MAC protocols regardless of their underlying allocation strategy. To that end a framework is developed in which the persistence of any protocol, contention- or schedule-based, can be measured. The framework is used to measure and compare the persistence levels of two prototypical contention- and schedule-based MACs, IEEE 802.11 and Scheduled p-Persistence. An ideal persistence that provides lexicographically max-min fair access to the channel is characterized, and used as a bandwidth allocation scheme. In addition to reducing the unfairness, simulations employing the ideal persistence values show increased throughput and decreased delay and drop rate when compared to either Scheduled p-Persistence or IEEE 802.11.