臺灣博碩士論文加值系統

本論文的主旨在開發一個異質性無線網絡的模型和分析架構，其功率控制法具有
針對不同情況相應的一些可適性策略以利實際的複雜環境。為了評估網路覆蓋率以
及不同環境下的平均頻譜效能，在本論文中，我們模擬了一個由多層基地台和分散
用戶組成的異質性網路。在每個不同的用戶連結機制以及具有功率控制的環境下，
每層基地台中的閒置基地台機率、網路覆蓋率的緊下界、平均頻譜效率都被推導而
出。此外，我們還進一步發現功率傳輸量以及基地台之間的直接關係，其給予建造
者達到其覆蓋率約束的期望。換句話說，它不僅節省了功率，也減少了在相應功率
控制策略下我們需要的基地台之數量。最後，我們通過使用異質性網路中的功率控
制，將我們以前的建模和分析架構應用於具有閒置基地台考量的蜂窩網絡，並提供
數值模擬和數學表示以驗證我們的發現。我們最後也得出結論，哪種類型的環境將
適合我們的功率控制方案，這可以作為一些研究人員嘗試在蜂窩網絡進行功率控制
時的建議。

In this thesis, we develop a general modeling and analyzing framework for a heterogeneous
wireless network (HetNet) which has some power control strategies for different situations
to adapt the complex environment in practice. In order to evaluate the link coverage and
the mean spectrum efficiency in different environment, we consider a HetNet consisting of
multiple tiers of BSs and randomly distributed users. In each user association scenario, the
void probabilities of the BSs in each tier are found and the tight lower bounds on the link
coverage and the mean spectrum efficiency by using power control with coverage constraints
are all derived. Furthermore, we also find the relationship between the transmit power and
the density of BSs, which gives the builders a guideline to achieve their coverage constraint.
In other words, it not only saves power but also reduces the number of BSs we need under
corresponding strategies. Finally, we apply our previous modeling and analysis framework to
the HetNet with the void cell phenomenon by using power control in the HetNet and provide
the numerical simulations and mathematical representation to validate our findings. We also
conclude that which kind of environment would be suitable for our power control scheme,
which can be viewed as an advice for some researchers trying to apply power control in
HetNets.

摘要ii
Abstract iii
Acknowledgements iv
Table of Contents v
List of Figures vii
Abbreviations ix
Symbols x
1 Introduction 1
1.1 Research Background and Motivation . . . . . . . . . . . . . . . . . . . . . 1
1.2 Prior Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 Contributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.4 Thesis Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Universal Cell Association 6
2.1 System Model and Preliminaries . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1.1 Heterogeneous Cellular Network Modeling . . . . . . . . . . . . . . 6
2.1.2 Universal Cell Association and Statistical Results . . . . . . . . . . . 8
2.1.3 Void Cell Issue in Cellular Network . . . . . . . . . . . . . . . . . . 11
3 Power Control with Coverage Constraints: The Case without Considering Void
Cells 15
3.1 Network Model and Assumptions . . . . . . . . . . . . . . . . . . . . . . . 16
3.1.1 The k-tier HetNet Modeling . . . . . . . . . . . . . . . . . . . . . . 16
3.1.2 The Derivation of Coverage Probability with Power Control . . . . . 16
3.1.3 The Green Issue in Power Control with Coverage Constraint . . . . . 18
3.2 Throughput Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.3 Numerical Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
4 Power Control with Coverage Constraints: The Case Considering Void Cells 38
4.1 Network Model and Assumptions . . . . . . . . . . . . . . . . . . . . . . . 39
4.1.1 Void Cell Issue in K-tier HetNets with Power Control . . . . . . . . . 39
4.2 Performance Evaluation of K-tier HetNet with Power Control . . . . . . . . 40
4.2.1 The Green Issue in Power Control with Coverage Constraint . . . . . 42
4.3 Throughput Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
4.4 The MRPA Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
4.5 Numerical Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
5 Conclusions and Future Work 53
5.1 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
5.2 Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Bibliography 56

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