In wireless local area networks (WLANs) often a station can potentially associate with more than one Access Point (AP). In IEEE 802.11, the station simply associates to the AP from which it has received the strongest signal during the scanning process. However, this may result in a significant load imbalance between several APs since some of them might be highly loaded while others are lightly loaded or even idle. Moreover, the multi-rate flexibility provided by several IEEE 802.11 variants can

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... cause low bit rate stations to negatively affect high bit rate ones and consequently degrade the overall network throughput. Therefore, a relevant question is how to optimally distribute stations among APs so as to maximize the overall network performance. This paper presents a centralized optimal association policy for IEEE 802.11 WLANs. We first derive the optimal solution for stations association. Then, we evaluate the effectiveness of the solution through the results obtained from Lingo optimization and NCTUns simulation packages.