臺灣博碩士論文加值系統

近幾年來無線通訊已經成為許多研究及產品發展的焦點，而其能夠不受空間限制的存取網路資源是最重要的觀念。對於無線網路的Call Admission Control，三個重要的考量點就是 — 有效率的使用有限的無線資源、低功率消耗需求和服務品質的提升。
基於上述的考量，本研究針對IEEE 802.11無線區域網路及藍芽的無線個人區域網路提出一套以模糊理論為基礎，用於此共存環境的智慧型切換系統 - FMSS。在使用者資源要求及換區(handoff)服務要求方面，我們根據使用者的的移動速度及頻寬需求，來將資源做有效的配置，並經由模糊化、解模糊化和模糊推論程序來執行切換判斷的方案。另外，在無線環境最大困難點要克服的就是頻率干擾的問題，我們也針對此共存環境的頻道干擾問題作分析，並根據IEEE 802.15.2此工作群所採用的解決方案來設計出共存干擾解決機制。
我們的模擬首先針對智慧型切換系統的Blocking Probability及System Utilization來做效能分析的量測，結果也顯示了縱使在經歷了嚴重的頻率干擾下，FMSS仍然優於同質性網路。而且當網路負載增加，我們的系統和同質性網路比較的差距值也拉大。當系統每秒達到二十個及三十個使用者來要求網路服務時，FMSS在Blocking Probability方面比無線區域網路分別低20.57%及11.74%。而在System Utilization方面也比同質性網路高3.51%及5.87%。
此外，我們也針對Queue Length、Loss Rate及End-to-End Delay來評估互連網路的效能。在Queue Length的分析中，閘道器的佇列中的封包數與每秒流進閘道器的封包數成正比。而在Loss Rate的分析中，Loss Rate會隨著閘道器佇列大小的增加而減少。相對著，閘道器佇列大小的增加則會造成End-to-End Delay的增加。

In the modern world of wireless communications, the concept of wireless global coverage is of the utmost importance. Three key considerations of call admission control in wireless networks are efficient use of scarce resource, the lower power consumption, and quality-of-service improvement. Based on the aforesaid considerations a two-tier service architecture with fuzzy-based switching scheme was proposed in an IEEE 802.11 (WLAN) and bluetooth (WPAN) coexistence service environment. In the environment combinational channels are allocated to new or handoff services according to some acceptance criterion and service facility such as the motion speed, and traffic characteristics. Through the fuzzification, defuzzification, and inference procedures, a switching decision-making scheme was performed.
Simulation results were shown that the measured performance in terms of service blocking probability and system utilization from the fuzzy-based two-tier model, which experiences a severe radio mutual interference had better than that of homogeneous networks. In heavy traffic load, the differences of blocking probability between FMSS and WLAN increase. When new call rates are 20 new calls per second and 30 new calls per second, FMSS is 20.57% and 11.74% lower than WLAN, respectively. It is also better than homogeneous networks at 3.51% and 5.87% in system utilization.
Moreover, the service interworking performance in terms of queue length, traffic loss rate and end-to-end delay were also evaluated. In the queue length analysis, the gateway queue length is in the direct proportion with the size of the traffic flow. In the loss rate analysis, the loss rate decreases when the gateway queue length increasing. On the contrary, the end-to-end delay increases when the gateway queue length increasing.

Chapter 1 Introduction
Chapter 2 Background Knowledge
Chapter 3 Interference Analysis
Chapter 4 Proposed Fuzzy-Based Switching Scheme
Chapter 5 Performance Analysis
Chapter 6 Conclusion and Future Work

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