Performance analysis of general backoff protocols

Abstract

In this paper, we analyze backoff protocols, such as the one used in Ethernet. We examine a general backoff function(GBF) rather than just the binary exponential backoff (BEB) used by Ethernet. Under some mild assumptions we find stability and optimality conditions for a wide class of backoff protocols with GBF. In particular, it is proved that the maximal throughput rate over the class of backoff protocols is a fixed function of the number of stations (N) and the optimal average service time is about Ne for large N. The reasons of the instability of the BEB protocol (for a big enough input rate) are explained. Additionally, the paper introduces novel procedure for analyzing bounded backoff protocols, which is useful for creating new protocols or improving existing, as no protocol can use unbounded counters.

Keywords

• Ethernet
• backoff protocol
• contention resolution
• stability
• optimality
• queuing theory