臺灣博碩士論文加值系統

在無線隨意區域網路(wireless ad hoc network)系統裏，媒體存取層的設計與實體層的能力充分影響著系統的效能與容量。本論文將提供一全新以CDMA為基礎的無線隨意區域網路系統，並且設計一媒體存取協定來配置各通信節點(node)在資料通道(data channel)上分割的時槽(time slot)之演算法以及在控制通道(control channel)上競爭存取的方式來加強系統的效能與容量。在資料通道裏，我們將一個時框(frame)分為164個時槽，每個時槽可以依照固定式時槽配置演算法(fixed time slot allocation; FTSA)和混合式時槽配置演算法(mixed time slot allocation; MTSA)分配的結果傳送固定位元速率(constant bit rate; CBR)，變動位元速率(variable bit rate; VBR)或是可用位元速率(available bit rate; ABR)的流量類別。當節點在競爭通道上取得虛擬雜訊碼(pseudo noise code; PN code)與傳送的時槽後，將同時保證傳送的頻寬。通常在同一時槽裡，CBR最多可以有41組節點同時傳送資料，而VBR最多可以有17組節點同時傳送資料，ABR則最多可以有11組節點同時傳送資料。在控制通道裏，我們使用碰撞避免式載波偵測多重存取(carrier sense multiple access with collision avoidance; CSMA/CA)的競爭方式讓各節點取得傳送的PN Code以及配置的時槽，然後在資料通道使用。經過模擬程式的結果，證明系統的效能與容量提升了數倍。

In wireless ad hoc network system, the design of medium access control (MAC) layer and the ability of the physical layer sufficiently affects the performance and capacity of the system. In this paper, we propose a new MAC layer protocol in the wireless ad hoc network system based on code division multiple access (CDMA). The channel has been divided into control channel and data channel, in which a data channel is divided into 164 slots. The proposed MAC layer protocol may allocate the slots in each frame for every node by two different slot allocation algorithms: fixed time slot allocation (FTSA) and mixed time slot allocation (MTSA). Each slot can be used to transmit different traffic types such as constant bit rate (CBR), variable bit rate (VBR), and available bit rate (ABR). A node obtains a guaranteed bandwidth to transmit its packets after obtaining a set of pseudo noise code (PN code). Generally 41 sets of PN codes can be used to transmit CBR traffic in the same slot, while 17 and 11 sets of PN codes are used to transmit VBR and ABR traffics, respectively. In the control channel, we use carrier sense multiple access with collision avoidance (CSMA/CA) for each node to contend the PN code from the available PN code table and the data slots in each frame used in data channel. Simulation results show that the system performance has been improved.

中文摘要……………………………………………………....iv
英文摘要……………………………………………………….v
圖表索引 ……………...………………………….........……....ix
第一章 緒論 ……………………………………………….……...…..1
1.1 無線網路概述......……………………….……………...……….. 1
1.2 研究動機與方向……………………………….………..……….. 3
1.3 章節概要…..……..……………………………….……..….….… 4
第二章IEEE802.11 ad hoc網路和分碼多重存取技術介 紹………………………..….……………….……….…..….… 5
2.1 IEEE 802.11無線區域網路 ….………...…….……..……..….…..5
2.1.1 網路架構及特性簡介….…..……...…….…....…………….5
2.1.2網路硬體架構….…..……...…….…..…….……………..….6
2.2 分碼多重存取術 …...……………………………..…..………….. 9
2.2.1 分碼多重存取技術(CDMA)起源及標準化…..………...…9
2.2.2 分碼多重存取技術(CDMA)原理………...……….……...10
2.2.3 MC-CDMA系統架構…………………..………………….10
第三章 系統模型 ………………………….…..............................…13
3.1網路基本系統架構…………………………...…………..….….. 13
3.2協定系統架構……...…...…….…….…….……………………… 13
3.3流量類別對網內PN code組數之影響…………………………..15
3.4 Available PN Code Table建立………………..…………….……17
3.5定義RTS、CTS及時槽要求封包……………………….………..19
3.6網內同步機制…………………………………………………....21
3.7演算法…………………………………………………………....22
3.7.1演算法詳述……………………….……………………....24
3.7.2資料時槽內PN code之選用原則……………………….26
3.7.3 QoS的支援………………….…………………………....30
3.7.4新節點加入ad hoc網路……………………………..…...31

第四章 系統模擬與結果 …………...………………………….….33
4.1效能量測..………...…...…...……………………….…................33
4.1.1連線拒絕率(Call Blocking Rate) .......................................33
4.1.2傳輸效能(Throughput) .......................................................34
4.1.3時槽佔用率(Slot Occupation).............................................34
4.2系統參數….…...………….………………….……………….…. 35
4.2.1時框和時槽大小之決定……………………………...…..35
4.2.2流量模型…………………………………………………. 35
4.2.3其他系統參數………………………………………….… 37
4.3系統模擬結果…………………………….……………………...39
第五章 結論 ……………………………………..………...………...46
參考文獻 …………………………………………………..……….…47


圖表索引
圖2-1 有基礎架構的無線區域網路…….…….…………..……….….7
圖2-2 無基礎架構的無線區域網路………………………….……….8
圖2-3 多載傳送CDMA資料傳送端……………….………………..11
圖2-4 多載傳送CDMA資料接收端………….………………….….12
圖3-1 系統基本時框架構圖.……………….……………...….……..14
圖3-2 資料通道上的時框架構圖……………………..……….…….15
圖3-3 可用虛擬雜訊碼表格之格式…………………..……….…….18
圖3-4 RTS封包格式...……………………..…………..…...………..20
圖3-5 CTS封包格式.…….…...….……………….…………………..20
圖3-6 資料時槽要求封包格式….…………………………………...20
圖3-7 短ACK封包格式………………………………..……………20
圖3-8 協定範例中各連線要求資料.……………………………...…28
圖3-9 加入要求封包格式………………………….………….……..31
圖3-10 允許加入封包格式………….……………..…….……….…...32
圖4-1 各流量類別連線百分比….………....………………………...35
圖4-2 兩種演算法之傳輸效能的比較(不分類別所做的統計).........39
圖4-3 針對CBR(Voice)類別來比較兩種演算法的傳輸效能...........39
圖4-4 針對VBR(Video)類別來比較兩種演算法的傳輸效能...........40
圖4-5 針對ABR(Data)類別來比較兩種演算法的傳輸效能.............40
圖4-6 兩種演算法之連線拒絕率的比較(不分類別所做的統計) .....41
圖4-7 針對CBR(Voice)類別來比較兩種演算法的連線拒絕率........41
圖4-8 針對VBR(Video)類別來比較兩種演算法的連線拒絕率.......42
圖4-9 針對ABR(Data)類別來比較兩種演算法的連線拒絕率.........42
圖4-10 兩種演算法的時槽佔用率比較................................................43
圖4-11 每個連線要求平均碰撞次數....................................................43
表3-1 不同流量類別對位元錯誤率和可使用PN code組數之關係………………………………………..……………….…….16
表3-2 初始化的可用虛擬雜訊碼表格………………….………...…18
表3-3 Available PN Code Table使用狀況範例………..………....…29
表4-1 系統模擬參數………………………….………..…...…….….37
表4-2 不同流量形式之參數

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