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基于低压电力线正交频分复用系统虚载波改进信道估计算法
陈 可, 胡晓光
北京航空航天大学 自动化科学与电气工程学院,北京 100191
摘要:
分析低压电力线信道特性,提出了一种增加导频密度的信道估计算法。该算法用导频取代系统部分虚载波,再将新的正交频分复用符号中的导频进行重新分布,实现导频在系统子载波中等频率间隔分布,依靠导频频率间隔的减小,达到提高信道估计精度的目的;为了防止虚载波数量的减少导致符号间干扰的增加,对滤波器的设计进行了改进,将传统的升余弦窗函数与改进升余弦窗函数进行线性组合。此外,将低密度奇偶校验码应用于系统中,得到更加精确的信道频率响应特性。仿真结果表明,该信道估计算法可获得比传统正交频分复用系统更低的信道估计均方误差和误码率,且不降低系统符号传输速率。
关键词:  正交频分复用  信道估计  低密度奇偶校验  虚载波  滤波器  误码率  通信
DOI:
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基金项目:国家自然科学基金资助项目(50870511)
Improved channel estimation algorithm based on virtual carriers of low-voltage power line OFDM system
CHEN Ke, HU Xiaoguang
School of Automation Science and Electrical Engineering,Beijing University of Aeronautics and Astronautics,Beijing 100191,China
Abstract:
The channel characteristics of low-voltage power line are analyzed and a channel estimation algorithm with increased pilot density is proposed,which replaces part of VCs(Virtual Carriers) by pilots and redistributes the pilots in the new OFDM(Orthogonal Frequency Division Multiplexing) with equal frequency interval among subcarriers to increase the channel estimation precision by reducing pilot frequency interval. The filters of OFDM system are enhanced by the linear combination of the window functions of raised-cosine and better-than-raised-cosine to avoid the increase of inter symbol interference due to the reduction of VCs. The low density parity check code is applied in system to obtain the better response characteristics of channel frequency. The simulative results show that the bit error rate and mean square error of channel estimation by the proposed algorithm are lower than those of conventional OFDM systems while the symbol transmission rate of system is not decreased.
Key words:  orthogonal frequency division multiplexing  channel estimation  low density parity check  virtual carrier  electric filters  bit error rate  communication

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