Coupled 802.11 Flows in Urban Channels: Model and Experimental Evaluation

Abstract—Contending flows in multi-hop 802.11 wireless networks compete with two fundamental asymmetries: (i) channel asymmetry, in which one flow has a stronger signal, potentially yielding physical layer capture, and (ii) 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 work, 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 o...

• Type: Journal
• Year: 2010
• Where: INFOCOM
• Authors: Joseph Camp, Ehsan Aryafar, Edward W. Knightly
• Keywords: Channel State Information, Communications, INFOCOM 2010, Modulation Rate Adaptation, Physical Layer Capture