Rate-Based Active Queue Management for TCP Flows over Wired and Wireless Networks

Jun Wang,Min Song

doi:10.1155/2007/54038

Abstract

Current active queue management (AQM) and TCP protocol are designed and tuned to work well on wired networks where packet loss is mainly due to network congestion. In wireless networks, however, communication links suffer from significant transmission bit errors and handoff failures. As a result, the performance of TCP flows is significantly degraded. To mitigate this problem, we analyze existing AQM schemes and propose a rate-based exponential AQM (REAQM) scheme. The proposed REAQM scheme uses the input rate as a primary metric and queue length as the secondary metric. The objectives of REAQM are to stabilize networks with low packet loss, low packet delay, and high link utilization regardless the dynamic of network conditions. We prove the global asymptotic stability of the equilibrium based on Lyapunov theory. Simulation results suggest that REAQM is capable of performing well for TCP flows over both wired and wireless networks, and has comparable implementation complexity as other AQM schemes.

Highlights

The essence of network congestion control is that a sender adjusts its transmission rate according to the congestion measure of the underline networks
The main idea of rate-based exponential AQM (REAQM) is to use the mismatch between input rate and link capacity as the primary metric, which exploits the early feedback benefit of rate-based marking
REAQM uses queue length to compute a coefficient of rate mismatch and use it as a secondary metric

Summary

INTRODUCTION

The essence of network congestion control is that a sender adjusts its transmission rate according to the congestion measure of the underline networks. Other AQM schemes deploy a combination of queue length and input rate to measure congestion and achieve a tradeoff between queue stability and responsiveness. Current TCP/AQM algorithms assume that packet loss is mainly due to network congestion. Communication links have intrinsic characteristics that affect the performance of transport protocols including variable bandwidth, corruption, channel allocation delays, and asymmetry [5] All of these cause significant noncongestion packet loss. We present a new rate-based exponential AQM (REAQM) with explicit congestion notification (ECN) marking, and use REAQM to enhance the TCP performance over wireless links. Using ECN marking to notify senders of incipient congestion, REAQM overcomes the packet loss problem of burst data and errors over wireless links, and performs well for high degree of multiplex of flows over wired links.

RELATED WORK

Scheme description

Stability analysis

SIMULATIONS AND ANALYSIS

CONCLUSIONS