Diffusion Model of a Non-Integer Order PIγ Controller with TCP/UDP Streams.

Dariusz Marek,Joanna Domańska,Jakub Szyguła,Tadeusz Czachórski,Adam Domański,Jerzy Klamka

doi:10.3390/e23050619

Abstract

In this article, a way to employ the diffusion approximation to model interplay between TCP and UDP flows is presented. In order to control traffic congestion, an environment of IP routers applying AQM (Active Queue Management) algorithms has been introduced. Furthermore, the impact of the fractional controller and its parameters on the transport protocols is investigated. The controller has been elaborated in accordance with the control theory. The TCP and UDP flows are transmitted simultaneously and are mutually independent. Only the TCP is controlled by the AQM algorithm. Our diffusion model allows a single TCP or UDP flow to start or end at any time, which distinguishes it from those previously described in the literature.

Highlights

Network protocols control the transfer of information between a transmitter and receiver
The diffusion approximation method is employed to trace the behavior of the Active Queue Management (AQM) mechanisms applied to control Internet traffic
This article describes the use of the diffusion approximation to estimate the behavior of the AQM mechanisms, their influence on the evolution of the Transport Control Protocol (TCP) congestion window and potential cooperation of more TCP/UDP streams

Summary

Introduction

Network protocols control the transfer of information between a transmitter and receiver. The AQM mechanisms based on the optimization theory are usually complex and hard to tune [6] In this case, it is difficult to control the instantaneous queue length of the router [12]. The diffusion approximation method is employed to trace the behavior of the AQM mechanisms applied to control Internet traffic. Fluid flow approximation and discrete-event simulation to investigate the influence of the AQM policy based on non-integer order PI γ controller on the packet loss probability, the queue length and its variability. Evaluation (in close loop scenario) of the effectiveness of active queue management (AQM) mechanisms based non-integer order PI γ controller. This paper is organized as follows: In Section 2 one can find the literature overview of AQM mechanisms based on the control theory approach.

AQMs Based on the Control Theory Approach

Diffusion Approximation

Diffusion Approximation of the TCP and UDP Network Streams

Numerical Results

Conclusions