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研究生:賴昌成
研究生(外文):Chang-Cheng Lai
論文名稱:無線蜂巢式網路之適應性頻道分配策略
論文名稱(外文):Adaptive Channel Assignment Scheme for Wireless Cellular Networks
指導教授:陳俊良陳俊良引用關係
指導教授(外文):Jiann-Liang Chen
學位類別:碩士
校院名稱:國立東華大學
系所名稱:資訊工程學系
學門:工程學門
學類:電資工程學類
論文種類:學術論文
論文出版年:1999
畢業學年度:87
語文別:中文
論文頁數:59
中文關鍵詞:頻道分配策略固定式頻道分配動態式頻道分配混合型頻道分配無線蜂巢式網路馬可夫鏈
外文關鍵詞:Channel Assignment SchemeFixed Channel AssignmentDynamic Channel AssignmentHybrid Channel AssignmentWireless Cellular NetworksMarkov Chain
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中文摘要
由於無線頻譜是有限的,因此如何管理有限的頻譜便是一重要的議題。當無線頻譜被切割成有限個頻道時,管理頻譜的方法稱之為頻道分配管理。若頻道分配管理的策略是以頻道重複使用情形為基礎時,頻道分配管理的類別,基本上可分為固定式頻道分配(Fixed Channel Assignment)、動態式頻道分配(Dynamic Channel Assignment)以及混合型頻道分配(Hybrid Channel Assignment)三大類。固定式頻道分配適合用於使用者數目較多時,動態式頻道分配適合用於使用者數目少量時,混合型頻道分配則適合用於一般量使用者數目時。在我們的研究裡,我們提出一個新的混合型頻道分配策略,此策略包含了固定式、動態式以及混合型頻道分配,目的在於擷取各個頻道分配方式的優點,以期達到效能最佳化。
本研究中,我們以新用戶發出服務要求被拒絕的機率(new call blocking probability)及服務中的用戶跨區時要求服務被拒絕的機率(handoff call blocking probability)做為效能評估的依據。前者決定了所有要求服務的新用戶中被拒絕的百分比;後者表示服務中的用戶被不正常中斷服務的百分比。在適當的統計假設下,我們將無線蜂巢式系統模擬成多維的馬可夫鏈(Markov chain),並且使用分析的方法作效能的評估。實際上,從用戶的觀點而言,我們比較傾向於拒絕新用戶的要求服務,盡量不要中斷服務中的用戶,所以我們引進了用戶跨區優先權的方法(handoff priority method)到我們提出的混合型頻道分配策略中。
我們提出的混合型頻道分配策略相較於其他策略,同時具有新用戶發出服務要求被拒絕的機率及服務中的用戶跨區時要求服務被拒絕的機率的最低平均值,這是因為我們擷取過去所提出的頻道分配方法的優點而得到的結果。除了分析方法外,我們也討論了提出的混合型頻道分配策略中,頻道分配策略轉移機制的可能作法。
關鍵詞: 頻道分配策略、固定式頻道分配、動態式頻道分配、混合型頻道分配、無線蜂巢式網路、馬可夫鏈

Abstract
Because the radio spectrum is limited, how to manage the limited spectrum is an important issue since before. When radio spectrum is divided into channels, the way to manage spectrum is called channel assignment management. When channel assignment strategies are compared based on the manner in which co-channels are separated, they can be divided into Fixed Channel Assignment (FCA), Dynamic Channel Assignment (DCA), and Hybrid Channel Assignment (HCA). FCA performs well under heavy traffic load, DCA performs well under light traffic load, and HCA is suited to moderate traffic load. In this research we propose a new HCA scheme which takes advantage of all three schemes to reach the best performance, and the new HCA scheme is consisted kinds of channel assignment schemes.
In our research the new call blocking probability and handoff call blocking probability are referred to as the performance indices. The first determines the fraction of new calls that are blocked, while the second is the fraction of admitted calls that terminate prematurely due to dropout. We use an analytical method to do the performance measurement, and the wireless cellular system is modeled as a multi-dimensional Markov chain under appropriate statistical assumptions. In fact from the point of view of a subscriber we prefer to block a new call request rather than block a handoff call request, so we include the handoff priority methods to our proposed HCA scheme.
Our proposed HCA scheme has the lowest average new call and handoff call blocking probabilities because it takes advantage of the existing channel assignment schemes. Besides the analytical model, we also propose a transition mechanism of channel assignment schemes according to the analytical results.
Keywords: Channel Assignment Scheme, Fixed Channel Assignment, Dynamic Channel Assignment, Hybrid Channel Assignment, Wireless Cellular Networks, Markov Chain

Contents
List of Figures iv
List of Tables vi
中文摘要 vii
Abstract ix
1 Introduction 1
1.1 The Wireless Communication Market Development . . . . . . . . . . . . . . . . . .1
1.2 The Wireless Network Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 The Mobile Call Life . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.4 Channel Access Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.5 Channel Assignment Categories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
2 Channel Assignment Schemes 9
2.1 The Co-Channel Reuse Distance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2 Fixed Channel Allocations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.2.1 The Simple FCA Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
2.2.2 The Channel Borrowing Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . .11
2.3 Dynamic Channel Allocations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.3.1 The Centralized DCA Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
2.3.2 The Distributed DCA Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.4 Hybrid Channel Allocations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
2.5 The Proposed HCA Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
2.6 Mobile User Handoff Consideration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
2.6.1 Guard Channel Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.6.2 Queuing of Handoff Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.7 The Enhanced Proposed HCA Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
3 Analysis Model 21
3.1 Mathematical Background Knowledge . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.1.1 Mathematical Distribution Functions . . . . . . . . . . . . . . . . . . . . . . . .21
3.1.1.1 Uniform Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.1.1.2 Exponential Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
3.1.1.3 Poisson Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
3.1.2 Discrete-Time Markov Chain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.1.2.1 Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.1.2.2 Steady-State Probability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
3.2 Assumptions and Description of Analysis Model . . . . . . . . . . . . . . . . . . .25
3.2.1 Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
3.2.2 Analysis Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.3 Analysis of Channel Assignment Schemes . . . . . . . . . . . . . . . . . . . . . . . .29
3.3.1 State Diagram of FCA Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.3.2 State Diagram of DCA Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
3.3.3 State Diagram of HCA Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.4 Handling of Blocking Probabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
3.4.1 New Call Blocking Probabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.4.2 Handoff Call Blocking Probabilities . . . . . . . . . . . . . . . . . . . . . . . . 33
4 Results and Discussions 35
4.1 Performance Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.2 Setting Topology Environment for Analysis Model . . . . . . . . . . . . . . . . . .35
4.3 Analysis Results and Discussions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
4.4 Other Discussions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
4.4.1 Transition Concept of Proposed HCA Scheme. . . . . . . . . . . . . . . . .42
4.4.2 Analysis Model vs. Real System . . . . . . . . . . . . . . . . . . . . . . . . . . 44
5 Conclusions and Future Works 45
Appendix A Unique Solution of Markov Chain 47
Appendix B Solving of Transition Probability 49
Appendix C Analysis Flow Chart 51
Bibliography 57

[1] A.G. Garry, Cellular Communications Worldwide Market Development, Artech House, 1998.
[2] S.R. Theodore, Wireless Communications, Prentice Hall PTR, 1996.
[3] I. Katzela and M. Naghshineh, "Channel Assignment Schemes for Cellular Mobile Telecommunication Systems: A Comprehensive Survey," IEEE Personal Communications, June 1996, pp.10-31.
[4] M. Zhang and T.S. Yum, "The Non-Uniform Compact Pattern Allocation Algorithm for Cellular Mobile Systems," IEEE Trans. on Vehicular Tech., vol.VT-40, 1991, pp.387-391.
[5] T.S.Yum and W.S. Wong, "Hot Spot Traffic Relief in Cellular Systems," IEEE JSAC, vol. 11, 1993, pp.934-940.
[6] D. Cox and D.O. Reudink, "Dynamic Channel Assignment in Two Dimension Large -Scale Mobile Radio Systems," Bell Sys. Tech. J., vol.51, 1972, pp.1611-1628.
[7] R. Beck and H. Panzer, "Strategies for Handover and Dynamic Channel Allocation in Micro-Cellular Mobile Radio Telephone Systems," IEEE VTC, vol.1, 1989, pp.178-185.
[8] R.W. Nettleton, "A High Capacity Assignment Method for Cellular Mobile Telephone Systems," Proc. 39th IEEE VTC, 1989, pp.359-367.
[9] K. Okada and F. Kubota, "A Proposal of a Dynamic Channel Assignment Strategy with Information of Moving Directions," IEICE Trans. Fundamentals, vol. E75-a, 1992, pp. 1667-73.

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