分散型動態頻道配置於蜂巢式行動網路之通話允入模糊控制

Call admission fuzzy control of distributed dynamic channel assignment in cellular mobile networks

林智群(Chih-chun Lin)

指導教授 ： 洪士程

朝陽科技大學/資訊學院/資訊工程系/碩士(2012年)

摘要

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。

關鍵字

換手通話中斷率 ； 新通話阻斷率 ； 通話允入控制 ； 蜂巢式網路 ； 模糊系統

並列摘要

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.

並列關鍵字

Fuzzy system ； Dropping rate ； Blocking rate ； Cellular network ； Call admission control

參考文獻

[8] S.Y. Lin, S.C. Horng, T.Y. Chan, “Interference Avoidance Distributed Dynamic Channel Assignment for Cellular Network,” in Proc. 2011 International Conference of System Science and Engineering, pp. 588-592, Macau, June 6-8 2011.

[25] John Yen and Reza Langari, Fuzzy logic：intelligence, control, and information, Prentice-Hal, 1999.

[21] S. Yamanaka, H. Kawano and Y. Takahashi, “Modeling and performance analysis of cellular network with channel borrowing,” IEICE Transaction on Communication, vol.E85-B, no.5, pp.929-937, 2002.

[1] A. Boukerche, S. Hong, and T. Jacob, “A distributed algorithm for dynamic channel allocation,” Mobile Networks and Applications, vol. 7, no. 2, pp. 115–126, Apr. 2002.

[3] M. Kamble and R. Gupta, “A new framework for call admission control in wireless cellular network,” 2011 International Conference on Emerging Trends in Networks and Computer Communications(ETNCC), pp.178-181, 2011.