臺灣博碩士論文加值系統

在這篇論文中，我們利用多個空間信道的MIMO技術，透過估計網絡狀態，動態調整退避的基礎上，提出碰撞緩解增強了IEEE802.11e的增強型分佈式協調功能（EDCF）。我們利用這種多重空間通道緩解碰撞增強在 IEEE802.11e的EDCF。該計劃的核心思想，即所謂 MIMO為基礎的EDCF（MEDCF）。
我們首先要建立IEEE802.11e模型的物理層和MAC層包括所有細節的MEDCF計劃。其次，制定一個優化空間信道的共享程序，探空框架和退避的大小，然後，我們改變了探空幀長度對系統的性能，並找出最佳值的探空幀長度，最大限度地提高系統性能方面的防撞和傳輸介質的利用率。最後，我們模擬MEDCF計劃在單跳網絡。
在這篇論文中，我們研究的貢獻如下：
1.該計劃的基礎上優化網路空間信道共享。
2.該計劃進一步降低介質訪問衝突。
3.該計劃中提高了利用率。

In this thesis, we utilize the multiple spatial channels of MIMO technology with a dynamically tuned backoff based on the estimation of the network status to propose collision-mitigation enhancements to the IEEE 802.11e enhanced distributed coordination function (EDCF). We utilize such multiple spatial channels for collision mitigation enhancements to the IEEE 802.11e EDCF. The key idea of the scheme, which is called MIMO based EDCF (MEDCF).
We first have model the built-in IEEE 802.11e physical and MAC layers to include all the details of the MEDCF scheme. Secondly, formulate an optimization spatial channel sharing program that sounding frame and backoff size, and then, we changing the sounding frame length on the system performance, and that finds the optimal value of the sounding frame that maximizes the system performance in terms of collision avoidance and transmission medium utilization. Finally, we present simulation results of the MEDCF scheme over a single-hop network.
In this thesis, the contributions of our research are as follows:
1. The scheme based on optimized online spatial channel sharing.
2. The scheme further reduces medium access collisions.
3. The scheme boosts medium utilization.

Contens
摘要 Ⅰ
Abstract Ⅱ
Acknowledgement Ⅲ
Contents Ⅳ
List of Figures Ⅵ
List of Tables Ⅵ
Chapter 1 Introduction 1
1.1 Research motivation 1
1.2 The Proposed Schemes 4
1.3 Organization of this thesis 4
Chapter 2 Background 6
2.1 Random address 6
2.1.1 Aloha 6
2.1.2 CSMA A MIMO design for IEEE 802.11e network with utility maximization 8
2.2 Review of IEEE 802.11 MAC 10
2.2.1 Distributed coordination function 10
2.2.2 Point coordination function 13
2.3 Introduction of IEEE 802.11e 14
2.3.1 Enhanced distributed channel access 16
2.3.2 HCF controlled channel access 18
2.4 Introduction of MIMO design for IEEE 802.11e 21

Chapter 3 Our MIMO enhancements to the IEEE 802.11e EDCF mechanism 22
3.1 Simulation model 22
3.2 Optimal spatial channel sharing 25
3.2.1 Optimal sounding frame 25
3.2.2 Optimal backoff size 30
3.3 Simulation results: A single-hop network 32
Chapter 4 Conclusions 35
Reference 36

List of Figures
Fig. 2.1 Pure ALOHA protocol 7
Fig. 2.2 Slotted ALOHA protocol 8
Fig. 2.3 DCF transmission scheme 10
Fig. 2.4 DCF timing chart 12
Fig. 2.5 PCF timing chart 14
Fig. 2.6 IEEE 802.11 protocol layer 15
Fig. 2.7 EDCA model 17
Fig. 2.8 IFS relationship and related terms 18
Fig. 2.9 Beacon interval is cut into several SI in HCCA 19
Fig. 3.1 BEB 30
Fig. 3.2 BEB with EDCI 31
Fig. 3.3 MAC delay for different γ lengths and network loads 33
Fig. 3.4 Channel utilization for different γ lengths and network loads 34
Fig. 3.5 Throughput for different γ lengths and network loads 34

List of Tables
Table I IEEE 802.11n PARAMETER SETTINGS 24

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