基於IEEE P1901規格之PLC系統 基頻內接收機頻域等化器設計與實現

Design and Implementation of Frequency Equalizer for Digital Baseband Inner Receiver for PLC System Based on IEEE P1901 Specification

謝志宏(Chih-hung Hsieh)

指導教授 ： 薛木添

國立中央大學/資訊電機學院/電機工程學系/碩士(2015年)

摘要

電力線通訊 (Power Line Communication)，主要透過電力線，將數據或資訊以數位訊號處理方法進行傳輸，使用既有低頻（50/60Hz）的電力線路傳送寬頻的網路訊息，不需額外佈線及連接方便等優點，使其具”最後一哩”的優勢。但是電力線傳輸環境的不可預測干擾源以及大範圍線路阻抗變化，造成嚴重的雜訊干擾以及通道衰減。因此研究的重點在於如何解決電力線傳輸通道衰減以及抵抗雜訊干擾以提升傳輸效率。
本論文以IEEE P1901規格來設計一基頻接收機。此接收機包含了時域頻域轉換、同步與等化的功能。同步功能包含OFDM符碼邊界偏移估測和取樣時脈偏移估測與補償。等化部分包含通道效應估測與頻域等化器。IEEE P1901標準所制定的前導符元為512點，而傳送的data封包為4096點，為了得到相對應各子載波的通道效應，以前導符元作通道估測再做頻域內插，另外利用前導符元之間的相位差，得到SCO的初始值以加速SCO收斂。因為使用前導符元做通道估測和SCO Tracking，在收斂速度及補償上已有相當速度與準度，所以在頻域等化器方面採用極座標系LMS演算法，並針對可調整增益的數位座標軸旋轉計算器 (MGC-CORDIC)，提出改良的通道估測與等化流程，減少硬體面積，在模擬方面，使用C code模擬傳輸過程及傳輸中的不理想效應，並與FPGA、Gate-level結果進行驗證。

關鍵字

電力線通訊

並列摘要

Power Line Communication (PLC) is mainly about the transmission of information or data based on digital signal processing method. By using existing power distribution network as the transmission network, this method has the advantage of the “last mile” due to convenient connection and no need for extra wiring. However, unpredictable interference and a wide range of changing impedance, will result in severe noise interference and channel fading. Therefore, the researches in all fields have been focusing on how to solve the attenuation along the power line transmission channel and to improve transmission efficiency against noise interference.
In this dissertation a digital baseband receiver has been designed with respect to IEEE P1901 standard. The digital baseband receiver includes a time domain and frequency domain conversion, synchronization and equalization functions. The synchronization functions include symbol boundary detector and the sampling clock offset estimation and compensation. The equalization functions include channel estimation and frequency domain equalizer.
In IEEE P1901 standard the preamble is set to be 512 points and the transmitted data packet is set to be 4096 points. In order to obtain the channel effect corresponding to each subcarrier, preamble is used in channel estimation then interpolated. Because using preamble to realize channel estimation and SCO tracking, the gain will get better accuracy and speed in compensation and convergence. Therefore the proposed method improved the channel estimation and the equalization process to MGC-CORDIC, and adopted the Polar Coordinate LMS algorithm for the frequency domain equalizer. In addition, the proposed utilized the resource sharing mechanism to reduce the hardware area. And the C code has been used to simulate the transmission process and the undesirable effects during transmission. Finally, the proposed is designed and verified in TSMC 90nm CMOS process.

並列關鍵字

PLC

參考文獻

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