The brief arts and crafts of the ordinary fourdrinier are introduced first. After the intractable points of paper basis weight (BW) control are analyzed, an autotuning PID/PI control algorithm based on relay feedback ...The brief arts and crafts of the ordinary fourdrinier are introduced first. After the intractable points of paper basis weight (BW) control are analyzed, an autotuning PID/PI control algorithm based on relay feedback identification is proposed, which has such advantages as simple parameter adjustment, little dependence on process model, strong robustness and easiness to implementation. And it is very suitable for controlling such processes as BW loop with large time delay.展开更多
In order to meet the demands for high transmission rates and high service quality in broadband wireless communication systems, orthogonal frequency division multiplexing （OFDM） has been adopted in some standards. Ho...In order to meet the demands for high transmission rates and high service quality in broadband wireless communication systems, orthogonal frequency division multiplexing （OFDM） has been adopted in some standards. However, the inter-block interference （IBI） and inter-carrier interference （ICI） in an OFDM system affect the performance. To mitigate IBI and ICI, some pre-processing approaches have been proposed based on full channel state information （CSI）, which improved the system performance. A pre-processing filter based on partial CSI at the transmitter is designed and investigated. The filter coefficient is given by the optimization processing, the symbol error rate （SER） is tested, and the computation complexity of the proposed scheme is analyzed. Computer simulation results show that the proposed pre-processing filter can effectively mitigate IBI and ICI and the performance can be improved. Compared with pre-processing approaches at the transmitter based on full CSI, the proposed scheme has high spectral efficiency, limited CSI feedback and low computation complexity.展开更多
甚高频数据交换系统(Very high frequency Data Exchange System,VDES)作为新一代船舶通信系统,具有广阔的应用前景。由于卫星相对船舶的高速运动,VDES中上行应用特定消息(Application-specific Message,ASM)链路会产生较大的多普勒频移...甚高频数据交换系统(Very high frequency Data Exchange System,VDES)作为新一代船舶通信系统,具有广阔的应用前景。由于卫星相对船舶的高速运动,VDES中上行应用特定消息(Application-specific Message,ASM)链路会产生较大的多普勒频移,在接收端仅依靠已知训练序列估计的频偏等信道参数无法满足正确解调的性能要求。为此提出一种基于判决反馈的解调方法,通过分段解调,缩短每次解调的数据长度,提高解调时对频偏的容忍度,并利用每段解调的结果作为下一段未解调数据的导频,估计出当前数据中的信道参数。仿真结果表明,所提算法相较于无反馈相干解调算法性能大大提升。在上述研究的基础上,在可编程逻辑器件上实现了对ASM无导频上行链路的正确解调。展开更多
基金This project was supported by the National Key Project in the Ninth Fivc-Year Plan(97-619-02-03).
文摘The brief arts and crafts of the ordinary fourdrinier are introduced first. After the intractable points of paper basis weight (BW) control are analyzed, an autotuning PID/PI control algorithm based on relay feedback identification is proposed, which has such advantages as simple parameter adjustment, little dependence on process model, strong robustness and easiness to implementation. And it is very suitable for controlling such processes as BW loop with large time delay.
基金supported by the National Natural Science Foundation of China(60902045)the National High-Tech Research and Developmeent Program of China(863 Program)(2011AA01A105)
文摘In order to meet the demands for high transmission rates and high service quality in broadband wireless communication systems, orthogonal frequency division multiplexing （OFDM） has been adopted in some standards. However, the inter-block interference （IBI） and inter-carrier interference （ICI） in an OFDM system affect the performance. To mitigate IBI and ICI, some pre-processing approaches have been proposed based on full channel state information （CSI）, which improved the system performance. A pre-processing filter based on partial CSI at the transmitter is designed and investigated. The filter coefficient is given by the optimization processing, the symbol error rate （SER） is tested, and the computation complexity of the proposed scheme is analyzed. Computer simulation results show that the proposed pre-processing filter can effectively mitigate IBI and ICI and the performance can be improved. Compared with pre-processing approaches at the transmitter based on full CSI, the proposed scheme has high spectral efficiency, limited CSI feedback and low computation complexity.
文摘甚高频数据交换系统(Very high frequency Data Exchange System,VDES)作为新一代船舶通信系统,具有广阔的应用前景。由于卫星相对船舶的高速运动,VDES中上行应用特定消息(Application-specific Message,ASM)链路会产生较大的多普勒频移,在接收端仅依靠已知训练序列估计的频偏等信道参数无法满足正确解调的性能要求。为此提出一种基于判决反馈的解调方法,通过分段解调,缩短每次解调的数据长度,提高解调时对频偏的容忍度,并利用每段解调的结果作为下一段未解调数据的导频,估计出当前数据中的信道参数。仿真结果表明,所提算法相较于无反馈相干解调算法性能大大提升。在上述研究的基础上,在可编程逻辑器件上实现了对ASM无导频上行链路的正确解调。
