CACAO: Distributed Client-Assisted Channel Assignment Optimization for Uncoordinated WLANs

MPhil Thesis Defence


Title: "CACAO: Distributed Client-Assisted Channel Assignment Optimization for
Uncoordinated WLANs"

By

Mr. Xiaonan Yue


Abstract

IEEE 802.11 WLANs are becoming more and more popular in homes and urban areas. 
Compared to traditional WLAN setups (such as in campuses) where knowledgeable 
network administrators can make centralized decisions on channel selection for 
different access points (APs), APs in these networks are often deployed by 
network non-specialists in an uncoordinated manner, leading to unplanned 
topology, interference and therefore unsatisfactory throughput performance.

We consider in this paper a distributed channel assignment algorithm for 
uncoordinated WLANs, where APs can self-configure their operating channels to 
minimize interference with adjacent APs. We first formulate an optimization 
problem on channel assignment which overcomes some of the weaknesses 
encountered by uncoordinated WLANs. The problem is NP-hard, so we propose an 
efficient, simple and distributed algorithm termed CACAO (Client-Assisted 
Channel Assignment Optimization). In CACAO, the clients feed back their traffic 
information to their APs. This leads to better knowledge about network 
environment and better channel assignment decisions at the APs. We conduct 
extensive simulation study and comparisons using Network Simulator 2 (NS2). Our 
results show that CACAO out-performs other traditional and recent schemes in 
terms of TCP and UDP throughput with a similar level of fairness. Furthermore, 
it converges quite fast and reduces interference to a very low level.


Date:			Tuesday, 11 May 2010

Time:			10:00am - 12:00noon

Venue:			Room 3494
 			Lifts 25/26

Committee Members:	Dr. Gary Chan (Supervisor)
 			Dr. Qian Zhang(Chairperson)
 			Prof. Mounir Hamdi


**** ALL are Welcome ****