- 學位論文
感知無線網路中多重頻道媒介存取控制協定之研究
Exploring Multichannel MAC Protocols in Cognitive Radio Networks
摘要
在感知無線網路(Cognitive Radio Network)環境中，工作節點如何有效偵測並爭取到無線區域網路環境的傳輸頻寬是很重要的議題。雖然IEEE802.11標準規範可提供多重頻道(Multi-Channel)給無線區域網路者使用，但其制定的媒介存取控制(Medium Access Control, MAC)通訊協定只限定於單一通道進行資料傳輸。利用CSMA/CA(Carrier Sense Multiple Access/Collision Avoidance)的機制，可避免碰撞而造成資料的遺失，正在傳輸連結鄰近之節點需待該連結傳送完成後方可建立通訊連結，CT-MAC通訊協定是在此機制之下，考慮免執照頻帶(Unlicensed Band)的單通道在不干擾主連結情況下建立可平行傳輸(Concurrent Transmission)的連結之通訊協定，在此篇論文中筆者針對CT-MAC之方法做進一步的改進以增加網路傳輸容量( Throughput)。並進一步考慮在多重通道上，設計適用於多重通道的MAC協定並解決多重通道隱藏節點(Multi-Channel Hidden Terminal)的問題，同時藉由多個頻道來達成增加網路傳輸容量的目標。
並列摘要
In cognitive radio networks, how does communication nodes effectively sense and compete for the wireless network transmission bandwidth is a very important subject. Although the IEEE802.11 standard provides multiple channels for the Wireless Local Area Network (WLAN), but its Medium Access Control (MAC) is designed for transmission on single channel. Using CSMA/CA scheme can avoid collision and packet loss. However, the neighbors of transmitting nodes must wait until the transmission is over to establish their own communication links. Based on the CSMA scheme, CT-MAC can achieve concurrent transmissions without interfering primary communication links. In this thesis, we first revise CT-MAC to increase the throughput. Then, we consider the multi-channel environments and propose a multi-channel MAC protocol which can solve the Multi-Channel Hidden Terminal problem. Our experimental results show that the proposed MAC protocols can reduce access time and transmission time as well as increase the throughput dramatically.