DocumentCode :
1429978
Title :
Coupled 802.11 Flows in Urban Channels: Model and Experimental Evaluation
Author :
Camp, Joseph ; Aryafar, Ehsan ; Knightly, Edward
Author_Institution :
Electr. Eng. Dept., Southern Methodist Univ., Dallas, TX, USA
Volume :
20
Issue :
5
fYear :
2012
Firstpage :
1452
Lastpage :
1465
Abstract :
Contending flows in multihop 802.11 wireless networks compete with two fundamental asymmetries: 1) channel asymmetry, in which one flow has a stronger signal, potentially yielding physical layer capture; and 2) topological asymmetry, in which one flow has increased channel state information, potentially yielding an advantage in winning access to the channel. Prior work has considered these asymmetries independently with a highly simplified view of the other. However, in this paper, we perform thousands of measurements on coupled flows in urban environments and build a simple yet accurate model that jointly considers information and channel asymmetries. We show that if these two asymmetries are not considered jointly, throughput predictions of even two coupled flows are vastly distorted from reality when traffic characteristics are only slightly altered (e.g., changes to modulation rate, packet size, or access mechanism). These performance modes are sensitive not only to small changes in system properties, but also small-scale link fluctuations that are common in an urban mesh network. We analyze all possible capture relationships for two-flow subtopologies and show that capture of the reverse traffic can allow a previously starving flow to compete fairly. Finally, we show how to extend and apply the model in domains such as modulation rate adaptation and understanding the interaction of control and data traffic.
Keywords :
telecommunication network topology; telecommunication traffic; wireless LAN; wireless channels; wireless mesh networks; channel state information; coupled IEEE 802.11 flows; coupled flow measurements; data traffic; modulation rate adaptation; multihop 802.11 wireless networks; physical layer capture; reverse traffic; small-scale link fluctuations; topological channel asymmetry; traffic characteristics; two-flow subtopology; urban mesh network; Modulation; Physical layer; Probability; Receivers; Signal to noise ratio; Throughput; Transmitters; Access protocols; ad hoc networks; analytical models; channel asymmetry; information asymmetry; measurement; physical layer capture; wireless mesh networks;
fLanguage :
English
Journal_Title :
Networking, IEEE/ACM Transactions on
Publisher :
ieee
ISSN :
1063-6692
Type :
jour
DOI :
10.1109/TNET.2011.2181863
Filename :
6138319
Link To Document :
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