Fairness issues in a chain of IEEE 802.11 stations

TL;DR

This paper investigates fairness issues in IEEE 802.11 ad hoc networks arranged in a chain, revealing phenomena dependent on chain length and parity, and introduces a nonlinear model that aligns well with simulations to analyze fairness.

Contribution

It presents a new nonlinear modeling approach for fairness analysis in chain networks, including asymptotic behavior and methods to improve fairness.

Findings

Fairness varies with chain length and parity.

The nonlinear model accurately predicts fairness phenomena.

Long chains tend to exhibit good asymptotic fairness.

Abstract

We study a simple general scenario of ad hoc networks based on IEEE 802.11 wireless communications, consisting in a chain of transmitters, each of them being in the carrier sense area of its neighbors. Each transmitter always attempts to send some data frames to one receiver in its transmission area, forming a pair sender-receiver. This scenario includes the three pairs fairness problem, and allows to study some fairness issues of the IEEE 802.11 medium access mechanism. We show by simulation that interesting phenomena appear, depending on the number n of pairs in the chain and of its parity. We also point out a notable asymptotic behavior. We introduce a powerful modeling, by simply considering the probability for a transmitter to send data while its neighbors are waiting. This model leads to a non-linear system of equations, which matches very well the simulations, and which allows to study both small and very large chains. We then analyze the fairness issue in the chain regarding some parameters, as well as the asymptotic behavior. By studying very long chains, we notice good asymptotic fairness of the IEEE 802.11 medium sharing mechanism. As an application, we show how to increase the fairness in a chain of three pairs.