- 學位論文
IEEE 802.11室內無線區域網路之傳播模型
An Indoor Propagation Model for IEEE 802.11 Wireless Local Area Networks
摘要
無線區域網路技術，主要是使用在室內的環境，在室內的環境中，無線訊號的傳播跟在戶外的環境，有著很大的差異，因為室內環境的複雜度較高，無線訊號會因為 室內的阻礙物，產生多徑傳播和多徑反射，這些變數會使得無線訊號之強度變化和無線訊號的訊號品質很難加以預測。 在室內環境中，規劃建置無線區域網路時，如果只是小區域的建置無線區域網路，通常是依據建置者的規劃經驗，來決定無線網路存取點的安裝位置，再進行反覆之無線訊號優化調整。如果是大區域的規劃建置無線區域網路時，有兩種基本的方式，環境調查方式和使用內建無線訊號傳播模型的軟體輔助工具，但是以環境調查的方式，需要耗費大量的人力和時間成本；若是使用內建無線訊號傳播模型的軟體輔助工具的方式，因目前內建無線訊號傳播模型的軟體輔助工具並不完備，所運算出的結果並不夠精確。 目前國內的一般企業環境，在規劃建置無線區域網路時，還多是採用傳統的環境調查方式，雖能達到建置無線區域網路的效能目標，其建置期間對於人力、時間等成本的耗損太大。 因此，本研究建立出一適用於企業室內環境的無線訊號傳播模型，在現有的決定論模型與經驗論模型之間取得一平衡點，並考慮到無線訊號的衰變效應及反射效應，對室內無線訊號傳播的影響，使套用本研究之無線訊號傳播模型，所得到的室內無線訊號分佈，趨近於真實環境中無線訊號強度分佈之狀態，同時本研究也提出了在台灣的企業建築中，所常用的各種建築裝潢材質，對於無線訊號衰變的影響參數。 本研究以簡易的計算及量測方式，在不失去無線訊號強度預測精確性的條件下，使得無線區域網路規劃設計者，在無線網路建置前，能夠依據本研究之傳播模型，及套用本研究對室內環境之各種阻礙物衰減參數整理，在無線區域網路建置前，即可預先規劃設計出，適當的無線區域網路架構。
並列摘要
Wireless local area network widely applies indoors. Its propagation of wireless signals is much different from outdoors. The more obstacles are indoors, the more complicated effects will occur such as multi-path propagation and multi-path reflections. These effects will make magnitude change and quality of wireless signal become harder to predict. When planning a wireless local area network in small region indoors, its access point locations are usually decided by experiences of planners and optimized then again and again by adjustments. Otherwise, it will divide into two ways to plan in wide region. They are site survey and software-aided tools had built-in wireless signal propagation models. It will cost too much labor workforce and time to do site survey, and software-aided tools still have not owned a complete data base to make precise results. The environment of domestic enterprises usually adopts traditional site-survey to plan the infrastructure of wireless local area network more often than not. Though it can achieve the efficiency we expect, it costs too much labor workforce and time. Hence, a wireless propagation model under our research for general indoor environment of enterprises had been established and found the balance between the existing deterministic model and empirical model. We considered the effect of attenuation and reflection to wireless signals propagation indoors and adopted it into our models. Finally, the magnitude distributions of indoor wireless signals we measured are very close to the real environment. In this research, we also mentioned many kinds of decorative material often adopted by enterprises in Taiwan how they affected wireless signal attenuations. Simple ways to calculate and measure maintains precisely predictions in our research. They make designers of wireless infrastructures whom can take our propagation model to arrange every kinds of attenuation parameter caused by indoor obstacles before they start establishing their design. And they will design and plan an appropriate wireless local area network structure in advance.