臺灣博碩士論文加值系統

在使用指紋辨識法(Fingerprinting)的Wi-Fi室內定位系統中，接受訊號強度(Received Signal Strength; RSS)是最受歡迎的定位特徵之一。對使用接收訊號強度的定位系統而言，設備硬體間的異質性、使用者方位資訊的匱乏是值得討論的問題。
在不同情況下的接收訊號強度差異，會使系統的定位誤差增大。隨著科技的發展，個人通訊需求及多媒體訊息交流量的急遽增加，使用者需要更大的通訊頻寬及傳輸量，智慧型多天線通訊技術因應而生。通道狀態資訊(Channel Status Information; CSI)用以記載天線間的通道環境變換，提供更可靠、強健的定位特徵。
儘管通道狀態資訊提供較佳的定位特徵，但其所記載的資訊，在定位系統
上造成維度的大幅增加、模組複雜化和各種效應的雜訊，增加系統定位的挑戰。我們提出2個演算法來解決上述問題，首先運用統計分佈等化(Histogram Equalization; HEQ)，將接收訊號透過轉移函數投射到指定分布，不需額外的方位資訊，同時解決硬體不同、方位資訊匱乏的問題。資訊理論學習(Information Theoretic Learning; ITL)提供每個特徵對應每個參考座標的互信息(Mutual Information;MI)，得以選取較有用的特徵，提高計算效率及定位精確度。我們在實際環境開發我們的定位系統。實驗結果顯示我們提出的系統與現有的定位特徵比較，能降低10.56%至39.77%的67%誤差圓徑(circular error probable)。

Indoor positioning systems have received increasing attention for supporting locationbased
services in indoor environments. Received Signal Strength (RSS), mostly utilized
ngerprinting systems in Wi-Fi, is known to be unreliable due to environmental
and hardware eects. The PHY layer information about channel quality known as
Channel State Information (CSI) can be used due to its frequency diversity (OFDM
sub-carriers) and spatial diversity (multiple antennas). The extension of CSI dimensions
causes over-tting should be considered. This paper proposes two approaches
based on histogram equalization (HEQ) and information theoretic learning (ITL)
to compensate for hardware variation, orientation mismatch and over-tting problems
in robust localization system. The proposed method involves converting the
temporal{spatial radio signal strength into a reference function (i.e., equalizing the
histogram). This paper makes two principal contributions: First, the equalized RF
signal is capable of improving the robustness of location estimation, and second,
ITL greater discriminative components provides increased
exibility in determining
the number of required components and achieves better computational eciency.

List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x
Chapter 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Chapter 2. Background and Related Works . . . . . . . . . . . . . . . . . . . 6
2.1 Indoor Location Fingerprinting Systems . . . . . . . . . . . . . . . . 6
2.2 Received signal strength . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.3 Channel status information . . . . . . . . . . . . . . . . . . . . . . . 9
2.4 Robustness issue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.4.1 Hardware Variation in Devices . . . . . . . . . . . . . . . . . . 11
2.4.2 Orientation mismatch . . . . . . . . . . . . . . . . . . . . . . 13
2.4.3 Over-tting and Noise . . . . . . . . . . . . . . . . . . . . . . 14
Chapter 3. Proposed Algorithms . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.1 Problem Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.2 Histogram Equalization . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.2.1 Theoretical Foundation of Histogram Equalization . . . . . . . 18
3.3 Information theoretic learning . . . . . . . . . . . . . . . . . . . . . . 21
3.3.1 Entropy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.3.2 Joint entropy and Conditional Entropy . . . . . . . . . . . . . 22
3.3.3 Mutual Information . . . . . . . . . . . . . . . . . . . . . . . . 23
3.4 Proposed Indoor Positioning Algorithm . . . . . . . . . . . . . . . . . 24

3.4.1 Oine Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.4.2 Online phase . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.4.3 Localization Using the equalized RF signal . . . . . . . . . . . 27
Chapter 4. Experimental Results and Analysis . . . . . . . . . . . . . . . . . 30
4.1 Experimental Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4.2 Performance Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . 32
4.3 Variation of Reference Distributions . . . . . . . . . . . . . . . . . . . 39
4.4 Analysis of Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Chapter 5. Performance Evaluation on Channel Status Information . . . . . . 48
5.1 Experimental Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
5.2 Performance Evaluation and Analysis of Results . . . . . . . . . . . . 48
Chapter 6. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

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