臺灣博碩士論文加值系統

在隨意型無線網路(MANET: Mobile Ad Hoc Network)中目前所使用之通訊協定為美國電子電機工程協會(IEEE: Institute of Electrical and Electronics Engineers)所制定之802.11a、b、g 這三種，其中802.11b和g各有83.5MHz的頻寛而802.11a更是擁有高達300MHz的頻寛，但是目前的IEEE 802.11a、b、g這三種通訊協定都是使用單頻道(Single-Channel)的傳輸方式，而且根據實體層的調變方式得知，實際上採用單頻道的傳輸方式，只利用到所佔頻寛中的一部份甚至是一小部份而已。

在本篇研究論文中我們提出一個適用於隨意型無線網路上之多頻道並行傳輸機制稱為“Concurrent Multi-Channel Transmission”簡稱為CMCT，依據來源與目的端之間完成交換RTS、CTS的時間點來決定所使用的資料傳輸頻道，並且我們可以保證在同一個傳輸範圍內，不會有一對以上來源與目的節點選到同一個資料傳輸頻道，所以可以確保資料傳輸不會發生碰撞，以逹到多頻道(Multi-Channel)並行(Concurrent)的傳輸方式，期望能充分利用剩餘的頻寛，以提升網路整體的輸出量(Throughput)，並且降低資料封包的傳輸延遲時間，CMCT的主要目的在於改善目前IEEE 802.11a、b、g中頻寛利用率不佳的問題，導致整體的輸出量無法有效的提升。

我們所提出之CMCT的方法中每個節點只須配備一個無線天線，此外我們假設網路上的節點都有一個唯一的識別號碼，並且存在一個所有節點一致認可的全域的時間。

The communication protocol 802.11a, b, g that we currently used in wireless mobile ad hoc networks is specified by the IEEE: Institute of Electrical and Electronics Engineers of United State. Both 802.11b and g keeps 83.5MHz bandwidth each. The 802.11a holds even up to 300MHz bandwidth. But as we can see that IEEE 802.11a, b, g this three protocol using only single channel to for transmission. According to the way of modulation from physical layer, we can know that using single channel transmission only used part of or even a small part of the owned bandwidth.

In this research paper we propose a multi-channel concurrent transmission mechanism called “Concurrent Multi-Channel Transmission”abbreviation to CMCT that using in wireless mobile ad hoc networks. The data transmission channel is decided according to the finishing time of succeed exchanging RTS, CTS between source and destination node. In the same transmission range we can guarantee that no more than one pairs of source and destination nodes will choose the same data transmission channel. So the data transmission is collision free to fulfill the ways of transmission for both multi-channel and concurrent. We expect to fully using the remaining bandwidth in order to increase the overall network throughput and decreasing the transmission delay of data packets. We focus on improving the poor bandwidth utility of IEEE 802.11a, b, g and lead to the inability to progress the whole network’s throughput.

The method CMCT we proposed each node need to equip with only one transceiver. Beside that we assume every node in the network associated with a unique identification. And there is a global time that is agreed by each node in the network.

摘要 iii
誌謝 v
目錄 vi
圖目錄 viii
一、緒論 1
1.1 研究背景 1
1.2 研究動機及目的 3
1.3 章節概要 4
二、相關研究討論 5
2.1忙音(Busy Tone)方法 5
2.1.1 DBTMA (Dual Busy Tone Multiple Access) 5
2.1.2 DUCHA (Dual-Channel MAC) 6
2.1.3 JMAC (Jamming-Based MAC) 6
2.2控制傳輸電力(Power Aware)方法 8
2.2.1 POWMAC (Power Controlled MAC) 8
2.2.2 DCA-PC (Dynamic Channel Assignment with Power Control) 9
2.2.3 MMAC (Multi-Channel MAC) 10
2.3結合忙音(Busy Tone)和控制傳輸電力(Power Aware)方法 11
2.3.1 PCMA (Power Controlled Multiple Access) 12
2.4跳頻(Hopping)方法 13
2.4.1 SSCH (Slotted Seeded Channel Hopping) 13
2.5其它方法 14
2.5.1 DCA (Dynamic Channel Assignment) 14
三、多頻道傳輸之媒體存取控制協定 15
3.1 IEEE 802.11 之媒體存取控制協定 15
3.1.1 IEEE 802.11 MAC Layer 中DCF 之運作模式 15
3.2 Hidden/Exposed Terminal Problem 17
3.2.1 Hidden Terminal Problem 17
3.2.1 Exposed Terminal Problem 18
3.3 CMCT MAC之系統架構及使用符號定義 20
3.4 控制訊號時間定義表和資料頻道選用時間表 21
3.5 CMCT MAC演算法 22
3.6 CMCT MAC實例說明 23
3.7 CMCT的優點 24
3.8 問題探討 25
四、系統實驗 27
4.1 系統實驗計畫 27
4.1.1 實驗環境 27
4.1.2 實驗計畫 27
4.2 實驗輸出項目定義 28
4.3 6個節點和3個資料流 28
4.3.1累計資料輸出量 29
4.3.2平均傳輸延遲時間 30
4.4 30個節點和15個資料流 30
4.4.1累計資料輸出量 31
4.4.2平均傳輸延遲時間 32
4.5 實驗結論 32
參考文獻 33

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