利用封包聚合機制增進IEEE 802.11無線電感知網路之效能

Abstract

隨著科技進步以及個人通訊裝置的興起，近年來無線網路的應用在種類以及數量上蓬勃發展，現有的頻帶多採用固定劃分的方式，由業者向政府機構申請職執照後發配，有研究指出此種固定劃分的機制造成整體的頻譜使用效率不佳，原因是部分所劃分出去的頻帶使用率不高，然而其他無執照的使用者並不能使用該頻帶。整體而言，可用於傳輸之無線網路頻譜逐漸感到不足，因此，近年來無線電感知網路的領域蓬勃發展，此技術的提出宗旨在於更有效率的利用無線頻譜，其中有一部份的機制可以達到在不干擾已劃分之頻段的主要使用者的情況下進而使用該頻段。 本篇論文主要繼承前人在IEEE 802.11無線電感知網路的研究成果，進行在更高資料傳輸率以及更新的主要使用者情況下進行驗證，並利用IEEE 802.11n封包聚合機制來改善現有機制的效能並且透過更新版的Estinet網路模擬器來驗證效能的提升以及對主要使用者的影響。

The concept of cognitive radio (CR) has become more and more popular and important due to the limitation of wireless bandwidth. The current wireless spectrum policy separates the wireless spectrum into many separated spectra and defines them into licensed band or non-licensed band. However, a research shows that the usage of licensed spectrum is less than 25%, which is very inefficient. In a CR network, the CR users are allowed to use the empty spectra in frequency, time and space under the constraints of not interfering with the primary users. The CR approach has a great potential to improve the utilization of licensed spectrum. In this thesis, we follow the previous research of an 802.11 Cognitive Radio Network and use the IEEE 802.11n frame aggregation mechanism to improve the performance and evaluate the result on Estinet network simulator. In our simulation result, we show that the frame aggregation mechanism successfully improves the performance of previous work and the frame aggregation mechanism does not increase the influence to PUs.