臺灣博碩士論文加值系統

蜂巢式網路基地台的通話可分為新通話(New Call)和換手通話(Handoff Call)兩種類型，若是基地台的頻寬不足以讓新通話使用，對於新通話會出現通話阻斷(Call Blocking)的情形，使得新通話無法接通。同理若頻寬不足以讓換手通話使用，則會出現通話中斷(Call Dropping)的情形，使得換手無法完成。通話中斷會帶給已通話中使用者需要重撥的困擾，因此針對換手通話中斷率(Handoff Call Dropping Rate)可低於新通話阻斷率(New Call Blocking Rate)的問題。本論文所提出之分散型動態頻道配置的蜂巢式網路之模糊通話允入控制。根據不同時間的可用頻道數、新通話阻斷率與換手通話中斷率的變化，利用模糊系統來進行新通話的允入控制，以達到較低的換手通話中斷率。由模擬結果得知，所提出之模糊通話允入控制方法確實能有效降低換手通話的中斷率。
本論文總共分為五個部份，第一部份，針對蜂巢式網路作一簡述，接著提出本篇論文之研究動機。第二部份，蜂巢式網路系統的說明。第三部份，針對模糊系統做完整的介紹，像是模糊化、模糊規則庫、模糊推論系統與解模糊化。第四部份，說明模糊通話允入控制(Fuzzy Call Admission Control，Fuzzy CAC)之相關方法，並介紹模糊通話允入控制系統執行步驟。第五部份，將模糊通話允入控制之方法進行實際範例的模擬以及數據結果之比較，最後，將所提之方法做個結論。

In cellular mobile networks, the service area is divided into cells each of which is equipped with a number of channels. Two types of calls share these channels are: New calls and Handoff calls. If a request is denied for the arriving new call, this call will be blocked and cleared from the system. If a request is denied for an arriving handoff call, this call will be dropped immediately. It is a common practice to give a higher priority to the handoff calls as compared to new calls. On the other hand, giving too much priority to handoff calls will result in an excessive blocking rate of new calls. In this dissertation, we propose a call admission control scheme based on fuzzy system that is carried out in the base station. The proposed fuzzy system will control the admission of new call depended on the number of available channel, call blocking rate and call dropping rate simultaneously during the period to reduce the dropping rate of handoff calls. Test results demonstrate that our method reduces the dropping rate of handoff calls in cellular network effectively.
This dissertation consists of five parts, the first part is introduction of cellular network, then we propose this paper motivation. The second part is to describe cellular network system. The third part, we introduce fuzzy system, such as fuzzification, fuzzy rule base, fuzzy inference system and defuzzification.The fourth part, we’ll describe method of Fuzzy_CAC and introduce the execute step of Fuzzy_CAC system. Then, we compare Fuzzy_CAC schemes and result with real example simulation. Finally, we’ll be a conclusion.

摘要 I
Abstract III
致謝 V
表目錄 IX
圖目錄 X
第一章 緒論 1
1.1 蜂巢式網路介紹 1
1.2 研究動機 2
第二章 蜂巢式網路系統 4
2.1 蜂巢式網路介紹 4
2.2 電磁相容性限制 6
2.3 換手機制 11
2.4 分散型動態頻道管理 11
第三章 模糊系統 16
3.1 模糊系統介紹 16
3.2 模糊化 18
3.3 模糊規則庫 20
3.4 模糊推論系統 20
3.5 解模糊化 26
第四章 採用模糊系統的通話允入控制 29
4.1 三個輸入變數與單一輸出變數的模糊歸屬函數 29
4.2 27條模糊規則庫 36
4.3 大小合成模糊推論系統 37
4.4 面積中心法解模糊化 42
第五章 模擬結果與比較 43
5.1 模擬環境 43
5.2 不採用通話允入控制的模擬結果 45
5.3 採用模糊系統的通話允入控制的模擬結果 46
5.4 結果比較與討論 48
第六章 結論 55
參考文獻 56

表目錄
表4.2.1 模糊通話允入控制27 條規則 ...................................................... 36
表4.3.1 模糊通話允入控制27 條規則之模糊歸屬值 .............................. 39
表5.2.1 不採用通話允入控制不同流量負載 ............................................ 46
表5.3.1 採用通話允入控制不同流量負載 ................................................ 47
表5.4.1 不同流量負載採用模糊通話允入控制的阻斷率與中斷率 ......... 49

圖目錄
圖2.1.1 1 號至49 號單位細胞之編號 .......................................................... 6
圖2.2.1 單位細胞25 號使用了頻道K ........................................................ 7
圖2.2.2 第一層單位細胞 .............................................................................. 8
圖2.2.3 第二層單位細胞 ............................................................................... 8
圖2.2.4 第三層單位細胞 .............................................................................. 9
圖2.2.5 共同頻道限制 .................................................................................. 9
圖2.2.6 相鄰頻道限制 ................................................................................ 10
圖2.2.7 共同兩側頻道限制 ........................................................................ 10
圖3.1.1 利用模糊系統對新通話允入控制的基本架構 ............................. 17
圖3.2.1 三角形模糊化歸屬函數 ................................................................ 18
圖3.2.2 高斯模糊化歸屬函數 .................................................................... 19
圖3.2.3 梯形模糊化歸屬函數 .................................................................... 19
圖3.4.1 最大-最小合成法模糊推論步驟 ................................................... 24
圖3.5.1 解模糊化之結果 ............................................................................. 28
圖4.1.1 x1 模糊歸屬函數 ............................................................................ 31
圖4.1.2 x2 模糊歸屬函數 ........................................................................... 31
圖4.1.3 x3 模糊歸屬函數 ............................................................................ 32
圖4.1.4 決定變數y 模糊歸屬函數 ............................................................. 32
圖5.1.1Pattern #1 新通話的平均到達率 ..................................................... 44
圖5.1.2 Pattern #2 新通話的平均到達率 .................................................... 44
圖5.4.1 Pattern #1 只考慮新通話比較其阻塞率 ....................................... 50
圖5.4.2 Pattern #2 只考慮新通話比較其阻塞率 ....................................... 50
圖5.4.3 Pattern #1 只考慮換手通話比較其阻斷率 .................................... 52
圖5.4.4 Pattern #2 只考慮換手通話比較其阻斷率 ................................... 52
圖5.4.5 Pattern #1 平均100 通通話可用通道數 ........................................ 54
圖5.4.6 Pattern #2 平均100 通通話可用通道數 ........................................ 54

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