IEEE 802.11無線網路基地台動態分配頻道的策略

Abstract

現今無線網路的技術日趨成熟，由於開發無線網路產品的花費下降，降低了產品的價格，便廣泛的被消費者所接受，再加上無線網路佈置及使用上的方便性便使得許多學校及公司等會在其內部架設無線網路供學生或員工免費使用，在機場及飯店等也會提供無線網路給顧客收費使用。 在IEEE 802.11 Infrastructure mode[1]下，無線網路基地台間若使用相同頻道會對彼此造成干擾，然而網管人員在佈置無線網路時，為了覆蓋面積及訊號強度的考量，往往會將無線網路基地台佈置得較密，因此會造成附近的基地台數過多，而可使用的頻道數不夠的問題，由於使用者有可行動的特性，因此我們提出一個中央控制的方法動態調整無線網路基地台的頻道 最後我們實作在無線網路基地台端上，並透過實驗來驗證所提出的方法。

Nowadays, the wireless technology becomes more robust and the price for wireless devices continues to drop. The wireless network has been widely accepted by the market. Because the WLANs promise the convenient deployment and use, it makes the college or company to provide the WLANs for students or employees in their building. In the IEEE 802.11 Infrastructure mode, If the nearby wireless base stations use the same channel, they will mutually interfere with each others. But in order to cover the whole building or to provide better signal strength for end user, the network administrator usually deploys the wireless base station densely. Therefore, it cause that the numbers of nearby wireless base stations is less than the number of available channels. The user with the wireless device may have the mobility characteristic. We propose a centralized algorithm to dynamically assign channels for the wireless base stations and also propose a method to collect the position information of the wireless base stations in order to assist the dynamically channel assignment . Through detailed simulations we study the performance of the algorithms under various topologies and channel conditions. It shows that our proposed algorithm indeed increase the maximum throughput.