在現代社會中，快速興起的無線網路通訊協定造成可用的無線頻譜逐漸不敷使用，而近期興起的感知無線電（Cognitive radio）將是解決無線頻帶缺乏（spectrum scarcity problem）的一項關鍵技術，其允許我們在不干擾合法使用者的情況下使用已被註冊的頻譜。 本論文的主要目標是建立一個適用於隨建即連感知無線電網路（Cognitive radio Ad Hoc Networks）的輕度跨層級(Cross-Layer)的無線資料傳輸架構。在我們設計的協定中，包含兩個主要部份：(1)保證相遇(rendezvous)機會的無線跳頻（Media Access Control）媒體存取控制和(2)資料蒐集樹（tree-based）為基礎的資料傳輸模型；其主要功用是保證網路中各個節點相遇的機會，以及提供一個公平的一對一傳輸頻道、傳輸時槽分配排程。為了提供一個可信賴的感知無線電網路通訊協定，我們的跳頻技術將避免使用共有的控制頻道(common control channel)進行控制資料交換，同時保證節點間相遇的時間（週期）比已存在的跳頻技術更短；值得一提的是，我們的方法能夠在某些節點密度較高的網路情況下達成無碰撞的100％頻道使用率。在模擬中，我們不但能成功保證節點之間的相遇機會，同時也能減少合法使用者的出現對於傳輸效率的影響。 In modern society, the growing popularity of wireless communications causes the insufficient of wireless frequency bands. Cognitive radio (CR) technology becomes one of the key enabling technologies that can address the spectrum scarcity problem which enables sharing the licensed spectrum without interfere the transmission of licensed users. In this paper, we proposed a light-weight cross layer transmission scheme for CR Ad Hoc Networks (CRAHNs). The cross layer model includes a rendezvous guaranteed Channel Hopping (CH) sequence generating procedure and a tree-based transmission model which ensures the rendezvous demand over SUs and supports a pair-wise time slot and channel assignment to reach fairly transmission demand. To establish a reliable link in cognitive radio networks (CRNs), our channel hopping scheme performs data transmission without common control channel requirement, and provide smaller time-to-rendezvous (TTR) than previous works. The worth mentioning is the tree-based transmission model can conditionally achieves 100% spectrum utilization rate without any collision. The simulation results show that our scheme can reduce performance impact of incumbent occupation by licensed users and guarantee the rendezvous over SUs. Moreover, our scheme provides further throughput improvement in a high density network environment compared to existed works.
