2.4GHz 室內無線通道量測

2.4GHz Indoor Wireless Channel Measurement

林羿緯(Yi-Wei Lin)

指導教授 ： 馬席彬

國立清華大學/電機資訊學院/電機工程學系/碩士(2007年)

摘要

時變的信號多路徑傳播是無線通訊系統中的一個共通的現象。這個現象造成無線通訊頻道的高結構特性。這個現象一方面帶給我們非常珍貴的、多數無線通訊系統賴以存活之關鍵的時間多樣性與頻率多樣性。另一方面，假使我們沒有善加利用無線通訊所提供我們的提示，此一現象反而造成信號干擾。這樣的干擾將引起信號同步誤差、頻道預估誤差、以及資訊偵測誤差等種種系統問題。換句話說，如果我們探索無線通訊系統的頻道結構，我們將可獲的較優的信號同步、解決信號干擾的問題、因而進一步顯著的改進資訊偵測的正確性。因此，在設計無線通訊系統時，為了保證系統的操作效能及傑出的整體表現，探求無線通訊的頻道結構就成了首要的環節。
室內的無線通道量測結果，雖然會因為所處環境的不同，而造成通道特性的差異，但這些差異往往能夠將其做分類歸納。為了忠實反映室內無線通道的特性，此論文便在校內研發大樓一樓平面進行實際量測，利用向量網路分析儀，量測不同環境中各個量測點其頻率領域的變動情形。並進一步分析觀察信號在時間領域中，因多重路徑效應所造成的延遲擴散現象 。希望藉由量測結果與分析整合，歸納出室內無線通訊的統合特性，以利於無線通訊系統整體的設計，並能夠在不同的頻道環境中，有效決定基地台最佳的擺設。

關鍵字

時變的多重路徑傳播 ； 時間選擇性 ； 頻率選擇性 ； 無線通道

並列摘要

In the wireless communication systems, time-varying multi-path propagation is a common phenomenon, which introduces a rich channel structure into the radio interface. On one hand, this phenomenon brings us precious time diversity and frequency diversity which are crucial for the survival of a wireless system. On the other hand, if we do not make a good use of the wireless channel information, this phenomenon will instead cause signal interference which results in various system problems in terms of signal synchronization error, channel estimation error, and data detection error. In other words, by exploring the wireless channel structure, we can obtain better signal synchronization, mitigate the system interference, and thus significantly improve accuracy of data detection. Therefore, when developing a wireless communication system, in order to guarantee high efficiency and outstanding performance of such a system, it is important to find out the wireless channel structure.
In the indoor wireless channel measurement, the channel property usually differs a lot at different channel environments, which can be categorized into several types. In this thesis, we conduct numbers of measurements in several selected scenarios at Research-and-Development Building to realistically capture the channel structure in various wireless environments. A network analyzer is used to record the signal variations measured at different locations in the frequency domain. The measurements are then further analyzed to look into the delay spread caused by the effect of multipath propagation. We divide the analysis result into several distinct scenarios for various wireless communication environments so as to help make the best design of communication systems.

參考文獻

[1] 張正忠，”通道模型於無線用戶迴路性統環境應用之研究”，私立中原大

Communication Systems” ,BYU Wireless Communications Lab

[7] T. S. Rappaport, Wireless Communication, Principles and Practice, Prentice

Hall, 1999.

學，民國九十年