Research on the system error performance of coherent orthogonal frequency division multiplexing system with M-distribution in satellite-to-ground laser communication

In order to alleviate the influence of atmospheric turbulence on the performance of satellite-to-ground laser communication system,based on the M-distribution atmospheric channel model,a multi-carrier coherent orthogonal frequency division multiplexing (OFDM) modulation system was proposed for uplink and downlink in the satellite-to-ground laser communication.The closed-form expression of bit error rate (BER) of coherent OFDM modulation system was derived.The relationship between the zenith angle,receiving aperture,signal-to-noise ratio (SNR),optimal beam divergence angle,and optimal transmission radius and the BER were studied under weak,and strong atmosphere turbulence,and compared with binary coherent differential phase shift keying (DPSK) modulation.Both the theory and the simulation results show that compared with coherent DPSK modulation,the bit error performance of the coherent OFDM modulation system in the satellite-to-ground laser communication system is better.     

A 200 MHz 4.8 mW 3 V Fully Differential CMOS Sample-and-Hold Circuit with Low Hold Pedestal

Wide frequency bandwidth has been internationally allocated for unlicensed operation around the oxygen absorption frequency at 60 GHz. A power amplifier and a low noise amplifier are presented as building blocks for a T/R-unit at this frequency. The fabrication technology was a commercially available 0.15 m gallium arsenide (GaAs) process featuring pseudomorphic high electron mobility transistors (PHEMT). Using on-wafer tests, we measured a gain of 13.4 dB and a +17 dBm output compression point for the power amplifier at 60 GHz centre frequency when the MMIC was biased to 3 volts V_dd. At the same frequency, the low noise amplifier exhibited 24 dB of gain with a 3.5 dB noise figure. The AM/AM and AM/PM characteristics of the power amplifier chip were obtained from the large-signal S-parameter measurement data. Furthermore, the power amplifier was assembled in a split block package, which had a WR-15 waveguide interface in input and output. The measured results show a 12.5 dB small-signal gain and better than 8 dB return losses in input and output for the packaged power amplifier.Mikko Kärkkäinen received the M.Sc. degree in electrical engineering from the Helsinki University of Technology, Espoo, Finland, in 2000, and is currently working toward the Ph.D. degree at the Electronic Circuit Design Laboratory, Helsinki University of Technology. He is interested in millimetre wave circuit design.Mikko Varonen received the M.Sc. degree in electrical engineering from the Helsinki University of Technology, Espoo, Finland, in 2002. He is currently working toward the Ph.D. degree in electrical engineering at the Electronic Circuit Design Laboratory, Helsinki University of Technology. His research interests involve millimetre-wave integrated circuits.Pekka Kangaslahti received the M.Sc. and Ph.D. degrees in electrical engineering from the Helsinki University of Technology, Finland, in 1992 and 1999, respectively. Since 1999 he has been a visiting scientist at the NASA Jet Propulsion Laboratory, Pasadena, USA. His research interests include nonlinear microwave and millimetre wave monolithic circuits, especially for signal generation in telecommunication and radar applications.Kari A. I. Halonen was born in Helsinki, Finland, on May 23, 1958. He received the M.Sc. degree in electrical engineering from Helsinki University of Technology, Finland, in 1982, and the Ph.D. degree in electrical engineering from the Katholieke Universiteit Leuven, in Heverlee, Belgium, in 1987.From 1982 to 1984 he was employed as assistant at Helsinki University of Technology and as research assistant at the Technical Research Center of Finland. From 1984 to 1987 he was a research assistant at the E.S.A.T. Laboratory of the Katholieke Universiteit Leuven, enjoying also a temporary grant of the Academy of Finland. Since 1988 he has been with the Electronic Circuit Design Laboratory, Helsinki University of Technology, as senior assistant (1988–1990), and the director of the Integrated Circuit Design Unit of the Microelectronics Center (1990–1993). He was on leave of absence the academic year 1992–93, acting as R&D manager in Fincitec Inc., Finland. From 1993 to 1996 he has been an associate professor, and since 1997 a full professor at the Faculty of Electrical Engineering and Telecommunications, Helsinki University of Technology. He became the Head of Electronic Circuit Design Laboratory year 1998. From 1997 to 1999 he was an associate editor of IEEE Transactions on Circuits and Systems I. He has been a guest editor for IEEE Journal of Solid-State Circuits and the Technical Program Committee Chairman for European Solid-State Circuits Conference year 2000. He has been awarded the Beatrice Winner Award in ISSCC02 Conference year 2002.     

光纤通信系统中偏振损耗对偏振态的影响

推导出具有偏振相关损耗(PDL)器件的Stokes模型,研究了光纤通信系统中PDL对光信号偏振态(SOP)的影响。数值模拟结果表明,入射信号光偏振度(DOP)小于1时,PDL对出射信号光的DOP和强度有直接影响;当入射光DOP等于1时,PDL对出射信号光的DOP没有影响,但随PDL的增加,出射光强度迅速减小,且信号光的SOP变化加剧。     

ADSS光缆的力学计算

介绍了ADSS光缆的力学计算，给出了光缆弧垂、张力、应变和悬长等计算公式，并对普遍采用的“悬链线”和“抛物线”两种计算方法加以比较。     

楼宇智能控制系统总线电缆的研制

介绍了楼宇智能控制系统总线电缆的特点、性能，并结合实际生产，讨论了总线电缆的设计、制造技术及关键工艺控制和试验。     

相干光通信中的光学桥接器

相干光通信技术是提高接收机灵敏度,发展大容量高码率激光通信系统的重要技术手段,光学桥接器将信号激光和本振激光链接到光电探测器进行相干探测处理,是相干光通信系统的关键器件之一.对近20多年来发展的光学桥接器进行了总结和分类,介绍了不同光学桥接器的原理、构造和性能,分析了光学桥接器的关键技术.     

基于用户中断概率的D2D通信干扰协调与资源分配

在LTE系统中引入设备直传(D2D)通信技术,会因为D2D用户复用蜂窝用户资源进行通信而产生同频干扰.在现有的干扰协调与资源分配研究中,都需要基站获取各个通信链路的信道状态信息(CSI),但这样无疑会增加基站的信令负担.为减小干扰与基站的信令负担,提出了一种基于用户中断概率的干扰协调与资源分配算法,首先在保证蜂窝用户正常通信的情况下,通过限制D2D用户到基站间的距离来降低干扰;其次通过遍历所有蜂窝用户的频谱资源,选择能使D2D用户的总中断概率最低的频谱资源进行复用.仿真结果表明,所提算法能够在保证蜂窝用户正常通信的情况下,明显降低D2D用户的平均中断概率,同时还能够降低基站信令负担.     

支持多种航电通信协议系统的设计

以FPGA为核心、HI-1575和SFP为接口设计了一个可以支持1553B、FC．AE、FC—AE-1553B三种航电通信协议的开发板,并基于此开发板搭建网络系统,完成相应协议下的通信工作。同时,网络上的数据可以通过开发板上的PCIE、Ethemet接口实时地传输至计算机,并完成数据测试。     

基于谱线特征的调制方式自动识别方法

研究了基于谱线特征的通信信号调制方式自动识别方法,从信号的功率谱、二次方谱、四次方谱及包络平方谱中,提取出一组鲁棒性强的特征参数。在不需要先验知识的情况下,对卫星通信中常用的调制信号进行了自动识别。仿真结果表明,在信噪比大于5 dB时,总体识别率能达到97%以上,方案具有很强的实用性。     

无线信道模型研究与展望(一)

随着信息技术的迅猛发展,无线通信成为越来越重要的通信方式之一,从而对信道提出了更严格的要求。回顾并综述了常用的典型无线信道模型,对各种信道的特点和适应场景进行了详细的分析、对比与总结,为实际应用中根据不同环境选择合适的信道模型提供了参考。最后,对其中一些信道模型的优化方向给出了建议,并对信道模型的应用前景进行了概括与展望。