可見光通訊系統研究: 分波長多工技術之選擇性合併演算法與水下監測之應用

本論文中，主要在探討可見光通訊系統下，提出訊號合併技術應用於光感測陣列接收器上，所能提供的效能改善；同時提出應用可見光通訊系統在水下監測水中濁度以及流速。在可見光通訊系統中應用分波長多工技術達成多使用者環境已經被提出。傳統上，利用光電二極體作為可見光通訊接收器，會造成在接收端無法消除干擾和雜訊。本論文探討在光感測陣列接收器作為可見光通訊接收端，利用最大訊號對干擾加雜訊比率合併法(Maximum SINR Combining, MSC)設計適當的權重值，達到輸出訊號對雜訊加干擾比率(Signal to Interference plus Noise Ratio, SINR)最佳化，消除干擾和雜訊，然而如果使用光感測陣列接收器上所有的感測器，將提高計算複雜度以及感測器錯誤累積機率，因此本文提出兩種降低感測器使用個數的方法：1)利用線性方程組求稀疏解的概念，如l1-norm、共軛梯度法，合成MSC求解後的頻譜響應曲線；2)利用二元化粒子群演算法基於MSC求解尋找最佳的感測器組合。在模擬顯示我們提出的方法能最多能降低感測器70%的使用率且僅損失SINR 0.1(dB)。在水下監測系統中，水下濁度以及水下流速為兩項很重要的指標，然而在現有的儀器中，沒有低成本且可以同時量測水下濁度以及水下流速的儀器。因此我們提出利用可見光通訊模組量測水下濁度以及水下流速，我們透過擷取可見光接收信號的均方根值來量測水下濁度，並且利用可見光接收信號的包跡曲線之頻譜分析來量測水下流速。在水渠道模擬的實驗中，驗證我們所提出的方法。

關鍵字

可見光通訊系統；分波長多工；光譜感測器陣列；選擇合併演算法；濁度量測；流速量測

並列摘要

This thesis aim to explore visible light communication (VLC) systems. First, we provide a selected combining method for filter array receivers in VLC systems to improve the performance. Second, we provide a signal processing method for water surveillance system by using VLC modules. The wavelength division multiplexing VLC systems have been proposed to efficiently share the visible light bandwidth for users. Conventionally, the use of the photo-electronic as the VLC receiver encounter the unavoidable in-band interference. In our previous work, the solution for the interference mitigation has been presented by applying the Maximum SINR Combing (MSC) algorithm for the VLC system using filter array receivers. However, the issues of high computational complexities as well as error-propagation from corrupted sensors are arisen since hundreds of array-signals are adopted. Therefore, in this work, two methodologies based on MSC have been proposed. First, we proposed to synthesize the filter response from MSC algorithm by using the methods such as l1-norm and conjugate gradient method of solving the linear equations with sparsely solution. Second, we tend to search the optimal sensor combination for the MSC algorithm by using the binary particle swarm optimization. It shows that the proposed methods can at best reduce 70 percent usage of the sensors with only SINR 0.1 (dB) loss in the simulations. In underwater surveillance systems, water turbidity and water flow velocity are two important metrics. However, the existing equipment is expensive. Further on, no equipment can achieve both measurements simultaneously. Thus, we propose a simultaneous measurement by using the VLC modules. We extract the root-mean square value to associate to the water turbidity and use the frequency analysis for the envelope of the received signal to associate to the water flow velocity. The proposed methods have been verified by experimental setup in Laboratory.

並列關鍵字

Visible light communication ； Wavelength divide multiplexing ； Filter-array receiver ； Selected combining ； Water turbidity meter ； Water velocimeter

參考文獻

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可見光通訊系統研究: 分波長多工技術之選擇性合併演算法與水下監測之應用

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