一個多頻道多天線無線網狀網路的存取控制協定

Abstract

最近幾年，無線網狀網路使用無線多跳躍模式，不需有線電纜的架設，即可以經由無線網路將可上網的範圍擴大，已引起大家的關注，而無線網狀網路主要是利用多頻道以及多天線的架構，來增加網路吞吐量和減少延遲。因為標準的802.11存取控制協定只考慮到一個頻道和一個天線的使用，不適合使用於無線網狀網路，所以我們訂定一個適合於多頻道多天線的存取控制協定，這個協定主要是採用混合的頻道給予架構，這個架構可以輕易地解決會面問題，而為了解決多頻道隱藏節點的問題，我們利用等待一段時間來更新頻道的網路狀態，以減少碰撞的產生，而且提出了一個動態等待時間和一個動態給予頻道傳輸時間來增進天線的使用率。模擬結果顯示，此協定比之前也是使用混合式的協定效果要好。

In recent years, WMN (Wireless Mesh Network) which uses a multi-hop configuration to extend the reach of the last-mile access to Internet has come into public notice. WMN is characterized by the use of multiple orthogonal (non-overlapping) channels and multiple wireless interfaces. However, the MAC protocol in IEEE 802.11 standard was designed and suited for only one channel and one interface, so we need a new MAC protocol suited for multi-channel and multi-interface in WMN. In this thesis, we propose a new MAC protocol for WMN which uses a hybrid channel assignment strategy. Thus we can solve the rendezvous problem easily. In order to solve multi-channel hidden terminal problem, the proposed method uses a waiting time scheme to update network allocation vectors (NAVs). Moreover, we employ a dynamic staying period scheme and a dynamic waiting time scheme to improve the utilization of both interfaces and channels. In simulation results, the proposed protocol outperforms the previous MAC protocol with hybrid channel assignment.