臺灣博碩士論文加值系統

合作式波束成型是一種重要的合作式通訊技術，它可以協同許多散佈節點，直接傳送信號到單一節點無法送到的位置。欲實施合作式波束成型需要許多網路通訊協定的配合，包含：定位協定、資料散佈協定、時間同步協定等。其中定位協定的作用是獲取節點之間的相對位置，並藉由資料散佈協定讓許多節點擁有同一份信號，最後利用時間同步協定讓散佈的節點在同一時間傳送信號。然而這些通訊協定常受限於複雜度或環境而帶來一些誤差，例如時間及位置的誤差，有些節點收不到信號等協定失真。目前合作式波束成型的文獻雖偶有針對協定失真的討論與分析他們的影響，但沒有統一的數學模型出現，也沒有看到相關文獻針對協定失真所造成的系統效能降低做出補償的動作。本論文使用一個統一數學模型同時分析這三種網路通訊協定失真對合作式波束成型系統效能的影響，包含增益減少、指向偏差、波束寬度變化等。我們發現在目前常見的頻段，以定位失真影響最大。此外藉由適當部署節點位置，或利用通訊協定來選擇參與合作式波束成型節點，我們能夠有效避免因為協定失真所帶來的影響。希望藉由本論文的分析，可以提供相關研究針對協定失真造成的系統效能影響做進一步改善。

Collaborative beamforming is an important methodology in the field of cooperative communications. One node cannot transmit message to far distances, but collaborative beamforming can coordinate distributed nodes to transmit signals to achieve
this goal. To conduct collaborative beamforming, several protocols must be executed, including localization protocol, data dissemination protocol, and time synchronization protocol. The purpose of localization protocol is to acquire relative distances between nodes, and we take the advantage of data dissemination protocol to share message with all nodes. At last, time synchronization protocol is conducted to force nodes to transmit signals at presumed time. However, these protocols are often limited to their complexities or the environment and some “protocol artifacts” appear,
such as the time synchronization error, the location error, and message vanishment. Although related work about collaborative beamforming has tried to analyze and discuss
the impact of protocol artifacts, there is no unified math framework. There is no literature to compensate the system degradation due to artifacts, either. This thesis introduces a unified math framework to analyze the influence of protocol
artifacts, including mainbeam degradation, beam pointing error, and half-power beamwidth augmentation. We discover that the artifact of localization protocol influences
the system performance the most in general frequency bands. By suitable arrangement or protocol selection of nodes, we can avoid the impact of protocol artifacts effectively. We hope by analyzing and addressing the protocol artifacts, prospective system designers can have a better understanding on collaborative beamforming.

ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . ii
LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . v
LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . vi
CHAPTER 1 INTRODUCTION . . . . . . . . . . . . . . . . . . 1
CHAPTER 2 BACKGROUND . . . . . . . . . . . . . . . . . . . 4
2.1 Cooperative Communications . . . . . . . . . . . . . . 4
2.1.1 Introduction . . . . . . . . . . . . . . . . . . . . 4
2.1.2 Diversity Techniques . . . . . . . . . . . . . . . . 5
2.2 Beamforming Techniques . . . . . . . . . . . . . . . . 8
2.2.1 Beamforming in MIMO Systems . . . . . . . . . . . . 8
2.2.2 Collaborative Beamforming . . . . . . . . . . . . . . 9
2.3 Protocol Artifacts . . . . . . . . . . . . . . . . . . 10
2.3.1 Classification of Protocol Artifacts . . . . . . . . 10
2.3.2 Protocol Case Studies . . . . . . . . . . . . . . . 12
2.4 Related Work . . . . . . . . . . . . . . . . . . . . . 19
CHAPTER 3 ANALYSIS FOR GRID TOPOLOGY . . . . . . . . . 21
3.1 Ideal Power Pattern . . . . . . . . . . . . . . . . . 21
3.2 Assumptions on Protocol Artifacts . . . . . . . . . . 23
3.3 Average Power Pattern with Protocol Artifacts . . . . 25
3.4 Performance Degradation due to Artifacts . . . . . . . 29
3.4.1 Preliminary . . . . . . . . . . . . . . . . . . . . 29
3.4.2 Mainbeam Degradation . . . . . . . . . . . . . . . . 30
3.4.3 Directivity Reduction . . . . . . . . . . . . . . . 33
3.4.4 Beam Pointing Error . . . . . . . . . . . . . . . . 35
3.4.5 Half-Power Beamwidth Augmentation . . . . . . . . . 40

CHAPTER 4 ANALYSIS FOR ARBITRARY TOPOLOGY . . . . 42
4.1 Preliminary . . . . . . . . . . . . . . . . . . . . . 42
4.2 Transforming Arbitrary Topology to Grid . . . . . . . 43
4.2.1 Ideal Power Pattern . . . . . . . . . . . . . . . . 43
4.2.2 Average Power Pattern with Protocol Artifacts . . . 44
4.2.3 Mainbeam Degradation . . . . . . . . . . . . . . . 47
4.2.4 Directivity Reduction . . . . . . . . . . . . . . . 48
4.2.5 Beam Pointing Error . . . . . . . . . . . . . . . . 50
4.2.6 Half-Power Beamwidth Augmentation . . . . . . . . . 52
4.3 Examples . . . . . . . . . . . . . . . . . . . . . . 53
CHAPTER 5 ADDRESSING PROTOCOL ARTIFACTS . . . . . . 55
5.1 Adjusting Operating Frequencies . . . . . . . . . . . 55
5.2 Physical Deployment . . . . . . . . . . . . . . . . . 56
5.2.1 Finding Larger Peak Value . . . . . . . . . . . . . 56
5.2.2 Compensation for Protocol Artifacts . . . . . . . . 64
5.3 Protocol Selection . . . . . . . . . . . . . . . . . 71
5.3.1 Choosing Optimal Grid Topologies . . . . . . . . . 71
CHAPTER 6 CONCLUSION AND FUTURE WORK . . . . . . . 81
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