臺灣博碩士論文加值系統

在感知無線電網路(Cognitive Radio Network)的環境中，非認證使用者(Unlicensed users)都是預借使用頻帶，頻帶隨時可能要還給認證使用者，所以非認證使用者的頻帶資源都相當珍貴。而感知無線電網路有許多不同出發點設計出的媒體存取控制協定(Medium Access Control Protocol, MAC Protocol)，在時槽(Time-slotted)協定下，可以減少節點間競爭次數，讓頻帶資源可以更有效率的使用。所以本篇論文以C-MAC協定為基礎 (屬於時槽協定)，在信標週期裡透過動態調整signaling slot的機制，利用前一個超訊框 (superframe)所得到的碰撞次數、成功次數與預估到達率，推測出目前要加入群組的節點數。另一方面利用競爭者個數與時槽數事先計算出一個成功數與碰撞數期望值表，利用查表法預測出目前節點數，再依據期望成功率來設定signaling slot數，讓欲加入群組的節點可以有效率的加入，當節點迅速加入群組後也可以馬上進行傳輸，進而增進頻道使用率與傳輸效能。而本篇還有加入速率決定，數據傳輸行程，多渠道轉換機制和授權用戶干擾救援機制。本篇後續效能分析出在多個節點的情況下，整體效能較C-MAC更有效率。

In the cognitive wireless network environment, the unlicensed users are using the spectrum advance. Because the spectrum may have to return at any time the licensed user, unlicensed users of the spectrum resources are very precious. In cognitive wireless networks, there are many different starting point for the design of the Media Access Control Protocol (Medium Access Control Protocol, MAC Protocol). In the Time-slotted protocol, contenders can reduce the number of nodes so that resources can be more efficient spectrum utility. Therefore, this thesis based on C-MAC (It is a Time-slotted protocol) in the beacon period signaling slot through the dynamic adjustment mechanism, using the previous superframe by the number of collision and the number of successful pre-evaluate arrival rate is assumed to be the current number of nodes join the group. On the other hand, the use of the number of contenders with the slot of a number of expected value of collisions and the expected value of success. The use of lookup table method to predict the current number of nodes, and then the success rate based on expectations to set the number of signaling slot, to allow nodes to join the group to join can be efficient. When the node quickly joined the group can also be immediately after the transfer, and enhance the performance of channel utilization and transmission. This thesis also uses rate determining, data transmission scheduling, multi-channel switching mechanism and licensed user interference recovery mechanism to improve the C-MAC. The effectiveness of this follow-up analysis of a number of nodes, the overall efficient will more than C-MAC.

Contents
1 Introduction 1
2 RelatedWorks 4
2.1 Random Access Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2 Time-Slotted Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Hybrid Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.4 C-MAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3 Preliminary 10
3.1 System model and assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.2 Basic Idea and Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4 An Efficient Dynamic Adjusting MAC Protocol for Multi-Channel Cognitive Wireless
Networks 14
4.1 Dynamic Adjusting join mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.1.1 Initial Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.1.2 Data Transmission Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.2 Data Transmission Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.2.1 Rate determining and data transmission scheduling . . . . . . . . . . . . . . 18
4.3 Multi-channel Switching Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.4 Licensed user interference recovery mechanism . . . . . . . . . . . . . . . . . . . . 22
5 Performance Analysis 24
5.1 Average join time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.2 Packet delivery ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
5.3 Throughput . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6 Conclusion 30

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