1 Introduction
Decentralization nature of WiFi networks contributes to the pervasive application of WiFi but also makes WiFi inteference-limited. With the popularization of smart-phones and tablets, more and more applications rely on WiFi to deliver media-rich contents, resulting in the exponentially growing of wireless traffic demand. Intuitively, increasing the number of WiFi access points (APs) will accordingly increase the network capacity. However, the capacity of WiFi networks is mainly limited by interferences. Therefore, deploying more APs does not guarantee the improvement of the total network throughput; even worse, it may decrease the network throughput because these transmitters may contend with each others and cause mutual interferences.