無線高增益同頻中繼器回授消除模塊之研製

A Design of Echo Cancellation Modules for High-Gain On-frequency RF Repeaters

周聖翔(Sheng-Shiang Chou)

指導教授 ： 張正春

國立臺北科技大學/電資學院/電機工程系研究所/碩士(2014年)

摘要

本論文主要探討在寬頻通訊系統中，設計高增益同頻中繼器之數位回授消除模組，來增加中繼器訊號之涵蓋範圍。由於同頻中繼器具有傳送與接收端使用相同頻率且同時傳輸之特性，具有較短的延遲時間與複雜度，但也因此衍生出欲解決之問題，即接收端會接收到來自傳送端之回授訊號，此現象稱為回授干擾。
為了使高增益同頻中繼器能穩定使用在寬頻系統中，本論文設計之高增益同頻中繼器之回授消除模組(Echo Cancellation Module, ECM)，在回授消除模塊中，使用本論文所提出之動態調整參數方法配合自適應濾波器如LMS與NLMS，來抑制回授干擾。軟體模擬中，使用Simulink WCDMA End-to-End Physical Layer 3GPP 做為寬頻通訊訊號之平台，使用Matlab程式模擬中繼器回授消除模塊，在不同的剩餘隔離度下，比較1.定點與浮點運算與2.不同之收斂因子μ之影響，透過誤差向量幅度(EVM)驗證回授消除效能。最後，實現高增益同頻中繼器與真實訊號量測，透過訊號產生器、訊號分析儀與向量分析儀測試系統效能。根據模擬與實測結果顯示，本研究所設計之ECM架構至少能提高10db增益，且相較傳統LMS與NLMS法，在剩餘隔離度-20dB至 20dB之間，所提出的改良式方法能提供較佳的EVM。

關鍵字

無線通訊 ； 干擾消除 ； 中繼器 ； 回授通道 ； 自適應演算法

並列摘要

In this thesis, we focus on design of echo cancellation modules for high-gain on-frequency RF repeaters (OFR) in wireless communication systems. Repeaters can be used to increase base station coverage. However, the on-frequency RF repeaters use the same frequency for both transmit and receive signals. This structure suffers from feedback interference signal that comes into the receive antenna from the transmit antenna. This is called feedback interference.
In order to keep the repeaters stable, we design echo cancellation modules (ECM) for high-gain repeater to reduce the impact of feedback interference in wireless communication systems. In this thesis, ECM systems are implemented based on adaptive filter using least mean square(LMS)、normalized least mean square(NLMS) and the propose method. We use the WCDMA End-to-End Physical Layer 3GPP as the simulation platform in Simulink to generate signal, and use Matlab to create the repeater modules and algorithms to verify the performance of the designed ECM. We test on fixed point, floating point, and compare the performance in different excess isolation with respective to different convergence factor μ. Moreover, we implement the high-gain OFR and use signal generators, signal analyzers and vector analyzers to verify the system performance.
According to our simulation and experimental results, our proposed ECM can achieve at least 10db gain. Our propose method has better performance and convergence rate than traditional methods at excess isolation -20db to 20db.

並列關鍵字

Interference cancellation ； repeaters ； feedback channel ； LMS algorithms

參考文獻

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