Understanding Performance for Two 802.11b Competing Flows

Kan Cai, Michael J. Feeley and Sharath J. George
Publishing date
April 07, 2007
8 pages
It is well known that 802.11 suffers from both inefficiency and unfairness in the face of competition and interference. This paper provides a detailed analysis of the impact of topology and traffic type on network performance when two flows compete with each other for airspace. We consider both TCP and UDP flows and a comprehensive set of node topologies. We vary these topologies to consider all combinations of the following four node-to-node interactions: (1) nodes unable to read or sense each other, (2) nodes able to sense each other but not able to read each other’s packets and nodes able to communicate with (3) weak and with (4) strong signal. We evaluate all possible cases through simulation and show that, for 802.11b competing flows, the cases can be reduced to 11 UDP and 10 TCP models with similar efficiency/fairness characteristics. We also validate our simulation results with extensive experiments conducted in a laboratory testbed.