| Abstract: | 在無線網路環境下，使用單一通道會導致隱藏節點及訊號干擾等的問題，也是網路效率降低的主要原因。而隱藏節點亦是因訊號干擾所引起的問題。現今有許多研究，利用多通道來解決訊號干擾的問題。多通道雖然能解決單通道的問題，但也衍伸出其他問題，例如:多通道隱藏節點及通道該如何配置的問題。實際上，一個好的通道配置演算法，不但可以提昇無線網路的效能，更可以解決多通道隱藏節點的問題。因此在本研究中，我們提出一個演算法，藉由協調周圍各AP的通道，來降低訊號干擾所產生的影響，並藉此提升AP與節點之間傳輸的效能。在我們提出的無線通訊網路中，將AP以同心圓的方式佈置並分群，通道亦分群並配置給各AP，以避免多通道隱藏節點的問題。實驗結果顯示，此演算法確實可以增進無線網路的單位時間內的傳輸量及效能。
In a wireless network, if single channel is employed, hidden terminal and radio interference problems may occur. The two problems are the two main factors that cause low network throughput. In fact, the hidden node problem results from radio interference. Up to present, many researchers have used multi-channel schemes to solve the interference problem. However, multi-channel results in other problems, e.g., multi-channel hidden terminal problem, and channel assignment problem. Actually, a well-defined channel assignment can effectively solve the former. Therefore, in this paper, we proposes a multi-channel assignment system, called corona-oriented multi-channel assignment system (COMAS), which coordinates channel usage in wireless networks to decrease radio interference among APs and nodes so as to improve network throughput and efficiency, particularly when many nodes are connected to APs. In COMAS, APs are deployed as concentric circles, named coronas, and channels are grouped and then allocated to coronas. We also cluster APs into groups, and schedule available channels to avoid radio interference and multi-channel hidden terminal problems occuring among adjacent AP groups and among APs in a group. Simulation results show that COMAS can effectively improve wireless-network throughput, efficiency and channel utilization. |
