Performance Analysis of Markov Modulated 1-Persistent CSMA/CA Protocols with Exponential Backoff Scheduling

TL;DR

This paper develops a Markovian model for 1-persistent CSMA/CA protocols with exponential backoff, analyzing throughput and delay regions, and verifies findings through simulations.

Contribution

It introduces a Markovian queuing model for CSMA/CA with exponential backoff, deriving throughput and delay bounds, and highlights the impact of service time variance on delay.

Findings

Stable throughput exists even for infinite populations.

Bounded delay region is a subset of stable throughput region.

Simulation results confirm analytical predictions.

Abstract

This paper proposes a Markovian model of 1-persistent CSMA/CA protocols with K-Exponential Backoff scheduling algorithms. The input buffer of each access node is modeled as a Geo/G/1 queue, and the service time distribution of each individual head-of-line packet is derived from the Markov chain of the underlying scheduling algorithm. From the queuing model, we derive the characteristic equation of network throughput and obtain the stable throughput and bounded delay regions with respect to the retransmission factor. Our results show that the stable throughput region of the exponential backoff scheme exists even for an infinite population. Moreover, we find that the bounded delay region of exponential backoff is only a sub-set of its stable throughput region due to the large variance of the service time of input packets caused by the capture effect. All analytical results presented in this paper are verified by simulations.