Channel assignment based on conflict-area for reducing interference in large-scale WLANs

Using unlicensed spectrums is a key factor in popularity of WLANs. Meanwhile, the interference is becoming severer in coming time because of network expansion. Assigning channels for AP in distributed way only reduce interference around single AP rather than reducing system interference. However systematic optimizations usually require real-time information which increase complexity for applying. This paper identifies a idea for optimizing system interference from the view of several sub-areas. Actually, interferences spread regionally depending on signal propagation. Conflict-areas are divided according to the interfering range. We define an index to present interference in conflict-areas and the goal is to minimize maximum index of the areas. It means that interferences of the whole network are comparatively low and distributed evenly. Both the theoretical evaluation and experiments in real network show that the conflict-area method is reasonable. Average interferences in most conflict-areas under experiments are reduced (about 50%) or remain unchanged (about 40%).