IEEE 802.11 無線網路動態頻道分配策略

Abstract

隨著無線技術的日新月異，無線網路已經成為佈置區域網路的普遍選擇。通常為了使整棟建築佈滿無線訊號，網路管理員會選擇將無線基地台緊密佈置。但是另一方面在IEEE 802.11基礎架構模式(Infrastructure mode) [1]下，使用同一頻道的相鄰無線基地台可能會發生訊號干擾的情形。由於頻道數目的限制以及使用者會到處移動的關係，靜態的頻道規劃並不足以解決問題。如何動態且適當的調整無線基地台的頻道以增進整個網路的效能，是我們想要討論的主題。 在本論文中，我們提出兩個中央控制的演算法，根據無線基地台的使用情況來動態調整它的頻道。我們實作了其中一個演算法，並且透過實驗來比較本論文的方法及其他方法的效能優劣。實驗結果顯示，我們的方法的確增進了網路的效能，並且比其他方法表現更好。

With the rapid evolution of wireless technology, WLAN gradually becomes a common solution of setting up a local area network. In order to cover the whole building with wireless signals, the network administrators often choose to deploy the access points (APs) densely. On the other hand, under the IEEE 802.11 infrastructure mode, there may be interference between the nearby access points if they use the same channel. Static channel assignment is not good enough because of the limitation of channels and the mobility of users. How to change the channels of access points dynamically to speed up the throughput of the whole network is the main issue that we want to discuss. In this thesis, we propose two centralized schemes to assign the channels of access points dynamically according to the AP utilizations. We also implement one of our schemes and compare the performance of it with other methods by experiments. The experiment result shows that our methods indeed increase the network throughput a lot and achieve better performance than others.