脉冲位置调制(pulse position modulation,PPM)是无线光通信的经典调制方式之一。符号同步是实现PPM正确解调的关键技术。在分析帧同步码型和长度要求的基础上,设计了一种PPM帧结构,提出了利用帧同步来实现PPM符号同步的方法。论述了其...脉冲位置调制(pulse position modulation,PPM)是无线光通信的经典调制方式之一。符号同步是实现PPM正确解调的关键技术。在分析帧同步码型和长度要求的基础上,设计了一种PPM帧结构,提出了利用帧同步来实现PPM符号同步的方法。论述了其工作原理,并分析了其同步性能。结果表明该方法建立时间短,同步概率高,并具有自动调整功能,可实现性强。展开更多
Frame and frequency synchronization are essential for orthogonal frequency division multiplexing （OFDM） systems. The frame offset owing to incorrect start point position of the fast Fourier transform （FFT） window,...Frame and frequency synchronization are essential for orthogonal frequency division multiplexing （OFDM） systems. The frame offset owing to incorrect start point position of the fast Fourier transform （FFT） window, and the carrier frequency offset （CFO） due to Doppler frequency shift or the frequency mismatch between the transmitter and receiver oscil ators, can bring severe inter-symbol interference （ISI） and inter-carrier interference （ICI） for the OFDM system. Relying on the relatively good correlation charac-teristic of the pseudo-noise （PN） sequence, a joint frame offset and normalized CFO estimation algorithm based on PN preamble in time domain is developed to realize the frame and frequency synchronization in the OFDM system. By comparison, the perfor-mances of the traditional algorithm and the improved algorithm are simulated under different conditions. The results indicate that the PN preamble based algorithm both in frame offset estimation and CFO estimation is more accurate, resource-saving and robust even under poor channel condition, such as low signal-to-noise ratio （SNR） and large normalized CFO.展开更多
The article presents a novel orthogonal frequency division multiplexing （OFDM） frame synchronization method. The method uses the preamble that contains two identical halves, and the energy difference of the two simi...The article presents a novel orthogonal frequency division multiplexing （OFDM） frame synchronization method. The method uses the preamble that contains two identical halves, and the energy difference of the two similar parts of the received preamble in receiver is used to obtain the frame＇s correct starting point. Furthermore, an improvement of the proposed method is presented, which uses the preamble that can be divided into four similar portions, and the energy difference of the four similar parts of the received preamble in receiver is used to obtain the frame＇s correct starting point. The performances of the frame synchronization methods in multipath channel are compared in terms of mean square error （MSE） obtained by simulations. It can be seen from the simulation results that the proposed methods have better performances than Schmidl＇s, Minn＇s, and Park＇s method in multipath channel.展开更多
文摘脉冲位置调制(pulse position modulation,PPM)是无线光通信的经典调制方式之一。符号同步是实现PPM正确解调的关键技术。在分析帧同步码型和长度要求的基础上,设计了一种PPM帧结构,提出了利用帧同步来实现PPM符号同步的方法。论述了其工作原理,并分析了其同步性能。结果表明该方法建立时间短,同步概率高,并具有自动调整功能,可实现性强。
基金supported by the National Natural Science Foundation of China(6130110561102069)+2 种基金the China Postdoctoral Science Foundation Funded Project(2013M531351)the Nanjing University of Aeronautics and Astronautics Founding(NN2012022)the Open Fund of Graduate Innovated Base(Laboratory)for the Nanjing University of Aeronautics and Astronautics(KFJJ120219)
文摘Frame and frequency synchronization are essential for orthogonal frequency division multiplexing （OFDM） systems. The frame offset owing to incorrect start point position of the fast Fourier transform （FFT） window, and the carrier frequency offset （CFO） due to Doppler frequency shift or the frequency mismatch between the transmitter and receiver oscil ators, can bring severe inter-symbol interference （ISI） and inter-carrier interference （ICI） for the OFDM system. Relying on the relatively good correlation charac-teristic of the pseudo-noise （PN） sequence, a joint frame offset and normalized CFO estimation algorithm based on PN preamble in time domain is developed to realize the frame and frequency synchronization in the OFDM system. By comparison, the perfor-mances of the traditional algorithm and the improved algorithm are simulated under different conditions. The results indicate that the PN preamble based algorithm both in frame offset estimation and CFO estimation is more accurate, resource-saving and robust even under poor channel condition, such as low signal-to-noise ratio （SNR） and large normalized CFO.
文摘The article presents a novel orthogonal frequency division multiplexing （OFDM） frame synchronization method. The method uses the preamble that contains two identical halves, and the energy difference of the two similar parts of the received preamble in receiver is used to obtain the frame＇s correct starting point. Furthermore, an improvement of the proposed method is presented, which uses the preamble that can be divided into four similar portions, and the energy difference of the four similar parts of the received preamble in receiver is used to obtain the frame＇s correct starting point. The performances of the frame synchronization methods in multipath channel are compared in terms of mean square error （MSE） obtained by simulations. It can be seen from the simulation results that the proposed methods have better performances than Schmidl＇s, Minn＇s, and Park＇s method in multipath channel.
