Analysis of the logical proximity between 802.11 access points

Resumo

802.11 campus networks have their access points deployed across the area the network has to cover. The physicalproximity between these access points is often well understood.Network managers have maps of the campus and of the location of the access points. Due to reflections indoor and between buildings, a mobile station may have connectivity to only one of two physically nearby access points. This may mislead the network manager into thinking that an area is densely covered when in fact mobile stations cannot connect to all of the access points in that area. This problem can have a dynamic nature if we consider people and objects that move around and change the properties of the propagation medium. In this paper we explore an alternative measure to physical proximity based on mobile station connectivity to the access points, which we call logical proximity. We take the ping-pong effect as a proxy to logical proximity. We use this proximity to characterize 802.11 campus network with over 200 access points and 14k users over a 2 year period. We report on the magnitude of the ping pong effect, theclustering of access points, and the degree distribution of theresulting access point proximity network.