Collision-free Operation in High Density WLAN Deployments
  WiFi's popularity has led to crowded scenarios composed of many Access Points (AP) and clients, often operating on overlapping channels, producing interference that gravely degrades performance. This misallocation of resources is often the result of multiple WLANs ownership, that is, networks are frequently setup automatically without considering neighbouring APs. In this work we overview the effect of Overlapping BSS (OBSS) from the perspective of the MAC layer, taking special interest on describing the advantages of eliminating collisions with Carrier Sense Multiple Access with Enhanced Collision Avoidance (CSMA/ECA). We propose a single Access Point (AP) and several multi-AP scenarios, including the residential building example proposed for testing the upcoming IEEE 802.11ax amendment. Results using the first NS-3 implementation of CSMA/ECA reveal the advantage of CSMA/ECA's deterministic backoff contention technique, confirming its suitability for very crowded scenarios. 
Luis Sanabria-Russo, Boris Bellalta, Nicol\`o Facchi, Francesco   Gringoli
cs.NI