On designing a novel PI controller for AQM routers supporting TCP flows

Nai Xue Xiong, Yan Xiang He, Yan Yang, Bin Xiao, Xiaohua Jia

Research output: Journal article publicationConference articleAcademic researchpeer-review

3 Citations (Scopus)


Active Queue Management (AQM) is an effective method to enhance congestion control, and to achieve tradeoff between link utilization and delay. The de facto standard, Random Early Detection (RED), and most of its variants use queue length as congestion indicator to trigger packet dropping. As an extension of RED, a novel AQM algorithm, called NPI-RED, is proposed in this paper. The NPI-RED is based on a novel proportional and integral controller, which not only considers the average queue length at the current time slot, but also takes into consideration the past average queue lengths within a round trip time. We provide a guideline for the selection of the feedback gains for TCP/RED system to stabilize the dynamics, make the queue length converge at a certain target and improve the network performance. We present the condition of asymptotic stability for the model in terms of the average queue length, by using a method, in which we construct a Routh table associated with the characteristic polynomial. Based on the stability condition and control gains selection method, the extensive simulation results by ns2 demonstrate that the NPI-RED algorithm outperforms than the existed AQM schemes in robustness, drop probability and stability.
Original languageEnglish
Pages (from-to)991-1002
Number of pages12
JournalLecture Notes in Computer Science
Publication statusPublished - 12 Sept 2005
Event7th Asia-Pacific Web Conference on Web Technologies Research and Development - APWeb 2005 - Shanghai, China
Duration: 29 Mar 20051 Apr 2005

ASJC Scopus subject areas

  • Theoretical Computer Science
  • General Computer Science


Dive into the research topics of 'On designing a novel PI controller for AQM routers supporting TCP flows'. Together they form a unique fingerprint.

Cite this