應用於競爭性無線網路之不易被偵測感知無線電方案

Abstract

隨著無線網路技術的發展，造成了所制定的許多無線網路標準必須共享無線傳輸頻帶。然而另一方面，也因為許多不穩定的資料流採用最高需求流量和許多爆發性的資料現象，造成在大部分的時間，頻道的使用率是相當低的。因此，無線傳輸頻道的這項資源是相當珍貴的，而技術關於提昇或是平衡頻道的使用率也被高度地重視。感知無線電(Cognitive Radio)技術於是被發展來解決這項問題。感知無線電的技術包含了許多範圍，包括不被察覺地使用頻帶的空檔、學習使用者之行為、自動調整以適應外在環境的變化等。這篇論文提出了一個可以確保主要使用者傳輸品質的感知借取演算法(cognitive borrowing algorithm)。在可以掃描環境的前提之下，若採用這個演算法，感知無線電通訊可以增加頻帶的使用率，並且對主要使用者只產生極小傷害。此外，此演算法還有分散式系統、適應性、低運算複雜度、和公平性等等優點。

With the fast development of wireless technology, a lot of user demands rely on wireless communication. Therefore, many wireless network standards are developed for certain purpose and that causes the radio frequency spectrums of the standards to have the overlap part. On the other hand, because of the usage of many requests from instable multimedia traffic and some user behavior of bursted traffic, the utilization of the channel might be low in most of the time. Therefore, the limited radio frequency spectra are treasurable. Issues about increasing or balancing spectrum utilization become more important. Moreover, issues about using spectrum holes have also been focused. CR (Cognitive Radio) technology is now developing for solving this critical problem. CR device is able to use a large range of frequency spectrum. The goal of CR is raise the channel utilization without influencing the original users. CR technology includes many aspects of researches, such as reusing spectrum holes invisibly, learning form users’ behavior, adjusting changes form the environment automatically. This thesis gives out a cognitive borrowing algorithm which can ensure the QoS of primary users. By using this algorithm with environment scanning capability, CR traffics increase the utilization of the channel with only rare damage to prior users. Moreover, the algorithm has the advantages of decentralized system, flexibility, low computing complexity, and fairness.