多頻道無線網狀網路之分散式頻道分配機制

Abstract

在IEEE 802.11中，頻道資源是十分有限且珍貴的。因此在多頻道 無線網狀網路下，為了能夠充分利用可用的頻道，頻道分配機制成為 一項重要的研究議題。頻道分配可分為集中式及分散式兩種方式。本 論文採用分散式頻道分配，每一個節點根據局部的資訊來選擇自己欲 使用的頻道。分散式頻道分配的優點是擁有較大的彈性和容錯性。然 而，「頻道振盪」是分散式頻道分配機制的主要問題，此問題為節點 反覆地改變頻道，導致頻道分配經過一段長時間後，仍無法達到穩 定，網路的吞吐量因此受到限制。在本論文中，我們提出了一個新的 分散式頻道分配機制，能夠有效的解決頻道振盪問題，並提高網路吞 吐量。實驗結果證實，我們所提出的方法無論在網路吞吐量或點對點 的延遲時間上，都比先前提出的分散式頻道分配機制具有更好的效 能。

In IEEE 802.11, channel resources are very limited and scarce. Thus channel assignment schemes which can effectively utilize available channels is one of the important issues in multi-channel wireless mesh networks. There are two approaches for channel assignment: centralized and distributed. We focus on distributed channel assignment, i.e., each node chooses its channel based on local information. The advantages of distributed approach are better flexibility and fault-tolerance. However, the problem of distributed channel assignment is channel oscillation which results that the channel assignment cannot converge for a long time and nodes change its channel repeatedly, and therefore the network throughput is throttled. In this thesis, we propose a new distributed channel assignment scheme to solve the channel oscillation problem, and to maximize the network throughput. Performance evaluation shows that our proposed algorithm improves the throughput and end-to-end delay in comparison to previously proposed distributed channel assignment schemes.