Energy efficiency(EE)of downlink distributed antenna system(DAS)with multiple receive antennas is investigated over composite Rayleigh fading channel that takes the path loss and lognormal shadow fading into account.O...Energy efficiency(EE)of downlink distributed antenna system(DAS)with multiple receive antennas is investigated over composite Rayleigh fading channel that takes the path loss and lognormal shadow fading into account.Our aim is to maximize EE which is defined as the ratio of the transmission rate to the total consumed power under the constraints of the maximum transmit power of each remote antenna.According to the definition of EE,the optimized objective function is formulated with the help of Lagrangian method.By using the Karush-KuhnTucker(KKT)conditions and numerical calculation,considering both the static and dynamic circuit power consumptions,an adaptive energy efficient power allocation(PA)scheme is derived.This scheme is different from the conventional iterative PA schemes based on EE maximization since it can provide closed-form expression of PA coefficients.Moreover,it can obtain the EE performance close to the conventional iterative scheme and exhaustive search method while reducing the computation complexity greatly.Simulation results verify the effectiveness of the proposed scheme.展开更多
It is well accepted that lower hybrid current drive （LHCD） is the most efficient method for non-inductive current drive in fusion devices and the effect of the current drive is dependent on not only microwave power ...It is well accepted that lower hybrid current drive （LHCD） is the most efficient method for non-inductive current drive in fusion devices and the effect of the current drive is dependent on not only microwave power but also its grill phase shift. This paper presents a new kind of feedback control system for antenna phase difference in LHCD experiments. In this highspeed control system, a lot of new technologies and methods are incorporated. The results of the experiments show a very good agreement with the system design.展开更多
It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output(MIMO) communication systems.In this letter,a simple proof is pre...It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output(MIMO) communication systems.In this letter,a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas.The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.展开更多
The micro-genetic algorithm (MGA) optimization combined with the finite-difference time-domain (FDTD) method is applied to design a band-notched ultra wide-band (UWB) antenna. A U-type slot on a stepped U-type UWB mon...The micro-genetic algorithm (MGA) optimization combined with the finite-difference time-domain (FDTD) method is applied to design a band-notched ultra wide-band (UWB) antenna. A U-type slot on a stepped U-type UWB monopole is used to obtain the band-notched characteristic for 5 GHz wireless local area network (WLAN) band. The measured results show that voltage standing wave ration (VSWR) less than 2 covers 3.1-10.6 GHz operating band and VSWR more than 2 is within 5.150-5.825 GHz notched one with the highest value of 5.6. Agreement among the calculated, HFSS simulated and measured results validates the effiectiveness of this MGA-FDTD method, which is efficient for UWB antennas design.展开更多
移动通信运营商在铁路沿线部署了公众移动通信网络,采用的数字全球通信系统(Global System of Mobile Communication, GSM)原理和制式与铁路全球移动通信系统(Global System of Mobile Communication for Railways, GSM-R)完全相同,对GS...移动通信运营商在铁路沿线部署了公众移动通信网络,采用的数字全球通信系统(Global System of Mobile Communication, GSM)原理和制式与铁路全球移动通信系统(Global System of Mobile Communication for Railways, GSM-R)完全相同,对GSM-R造成了一定干扰。为了对这些干扰源进行定位,提出了一种基于相差变化率的干扰源定位技术。该技术基于二元阵列接收系统,根据阵元与干扰源之间的时空关系,初始以方位角的变化率与干扰源位置建立关系模型,借助微分变形建立了以相差变化率为自变量的干扰源位置求解模型和解算方法。为了避免采集数据中的异常样本对最终的定位结果产生影响,设计了一种基于孤立森林的异常样本过滤算法,利用数据点自身的特征属性构建多维特征空间实现异常数据点的检测和消除。搭建实景环境对铁路沿线无线电数据进行采集并开展数据分析工作,结果表明所提基于孤立森林的异常样本过滤算法能够有效剔除异常数据,提高整体样本的质量。使用相同的已知位置干扰源无线采集数据开展与基于频差变化率的定位方法和基于振幅变化率的定位方法的定位能力对比试验,统计不同方法对于每个干扰源的最小定位误差,结果表明基于频差和振幅变化率定位方法的平均定位误差分别是所提方法的7.18、20.73倍,证明了所提方法的定位精度显著优于基于频差变化率的定位方法和基于振幅变化率的定位方法,具有较高的定位精度。展开更多
In this paper a method that combines transmit antenna selection and reduced-constellation detection in spatially correlated Multi-Input Multi-Output (MIMO) fading channels is presented. To mitigate the performance deg...In this paper a method that combines transmit antenna selection and reduced-constellation detection in spatially correlated Multi-Input Multi-Output (MIMO) fading channels is presented. To mitigate the performance degradation caused by the use of antenna selection that is based on correlation among columns, an iterative receiver scheme that uses only a subset of the constellation points close to the expected symbol value estimated in the previous iteration is proposed. The size of the subset can adapt to the maximum correlation of the sub-matrix after the simple antenna selection. Furthermore, the error rate performance of the scheme under linear Minimum Mean Square Error (MMSE) or Ordered Successive Interference Cancellation (OSIC) for the first run detection and different interleaver lengths is investigated while the transmit antenna selection is considered. The simulation results show a sig- nificant advantage both for implementation complexity and for error rate performance under a fixed data rate.展开更多
A simple and efficient design scheme of the continuous long slot leaky-wave antenna is developed. The key steps involved in the scheme are summarized. First, the cut-off frequencies of slot waveguides with different s...A simple and efficient design scheme of the continuous long slot leaky-wave antenna is developed. The key steps involved in the scheme are summarized. First, the cut-off frequencies of slot waveguides with different slot offsets are obtained by 3D finite-difference time-domain （FDTD） method, Second, the attenuation function a^a is estimated by the aperture distribution, and the attenuation function αrs is determined by the slot radiation. Finally, the attenuation function αrs is combined with the attenuation function αrs by the coefficient K. And an example in Ka band is presented. Moreover, the return loss of the E-plane Tee-junction （ET） and the radiation pattern of leaky-wave antenna are simulated. The scheme is verified by comparing with the experimental result.展开更多
基金supported by the National Natural Science Foundation of China(Nos.61571225,61571224)the Fundamental Research Funds for the Central Universities+2 种基金the Research Founding of Graduate Innovation Center in NUAA (No.kfjj20160409)the Qing Lan Project of Jiangsu,Shenzhen Strategic Emerging Industry Development Funds(No.JSGG20150331160845693)the Six Talent Peaks Project in Jiangsu Province(No.DZXX-007)
文摘Energy efficiency(EE)of downlink distributed antenna system(DAS)with multiple receive antennas is investigated over composite Rayleigh fading channel that takes the path loss and lognormal shadow fading into account.Our aim is to maximize EE which is defined as the ratio of the transmission rate to the total consumed power under the constraints of the maximum transmit power of each remote antenna.According to the definition of EE,the optimized objective function is formulated with the help of Lagrangian method.By using the Karush-KuhnTucker(KKT)conditions and numerical calculation,considering both the static and dynamic circuit power consumptions,an adaptive energy efficient power allocation(PA)scheme is derived.This scheme is different from the conventional iterative PA schemes based on EE maximization since it can provide closed-form expression of PA coefficients.Moreover,it can obtain the EE performance close to the conventional iterative scheme and exhaustive search method while reducing the computation complexity greatly.Simulation results verify the effectiveness of the proposed scheme.
基金Meg-science Engineering Project of the Chinese Academy of Sciences
文摘It is well accepted that lower hybrid current drive （LHCD） is the most efficient method for non-inductive current drive in fusion devices and the effect of the current drive is dependent on not only microwave power but also its grill phase shift. This paper presents a new kind of feedback control system for antenna phase difference in LHCD experiments. In this highspeed control system, a lot of new technologies and methods are incorporated. The results of the experiments show a very good agreement with the system design.
基金National Nature Science Foundation of China(No. 60672061)
文摘It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output(MIMO) communication systems.In this letter,a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas.The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.
基金supported by the Shanghai Leading Academic Discipline Project (Grant No.S30108)
文摘The micro-genetic algorithm (MGA) optimization combined with the finite-difference time-domain (FDTD) method is applied to design a band-notched ultra wide-band (UWB) antenna. A U-type slot on a stepped U-type UWB monopole is used to obtain the band-notched characteristic for 5 GHz wireless local area network (WLAN) band. The measured results show that voltage standing wave ration (VSWR) less than 2 covers 3.1-10.6 GHz operating band and VSWR more than 2 is within 5.150-5.825 GHz notched one with the highest value of 5.6. Agreement among the calculated, HFSS simulated and measured results validates the effiectiveness of this MGA-FDTD method, which is efficient for UWB antennas design.
文摘移动通信运营商在铁路沿线部署了公众移动通信网络,采用的数字全球通信系统(Global System of Mobile Communication, GSM)原理和制式与铁路全球移动通信系统(Global System of Mobile Communication for Railways, GSM-R)完全相同,对GSM-R造成了一定干扰。为了对这些干扰源进行定位,提出了一种基于相差变化率的干扰源定位技术。该技术基于二元阵列接收系统,根据阵元与干扰源之间的时空关系,初始以方位角的变化率与干扰源位置建立关系模型,借助微分变形建立了以相差变化率为自变量的干扰源位置求解模型和解算方法。为了避免采集数据中的异常样本对最终的定位结果产生影响,设计了一种基于孤立森林的异常样本过滤算法,利用数据点自身的特征属性构建多维特征空间实现异常数据点的检测和消除。搭建实景环境对铁路沿线无线电数据进行采集并开展数据分析工作,结果表明所提基于孤立森林的异常样本过滤算法能够有效剔除异常数据,提高整体样本的质量。使用相同的已知位置干扰源无线采集数据开展与基于频差变化率的定位方法和基于振幅变化率的定位方法的定位能力对比试验,统计不同方法对于每个干扰源的最小定位误差,结果表明基于频差和振幅变化率定位方法的平均定位误差分别是所提方法的7.18、20.73倍,证明了所提方法的定位精度显著优于基于频差变化率的定位方法和基于振幅变化率的定位方法,具有较高的定位精度。
基金Supported by the National Natural Science Foundation of China (No.60496311)China High-Tech 863 Plan (No.2006AA01Z264).
文摘In this paper a method that combines transmit antenna selection and reduced-constellation detection in spatially correlated Multi-Input Multi-Output (MIMO) fading channels is presented. To mitigate the performance degradation caused by the use of antenna selection that is based on correlation among columns, an iterative receiver scheme that uses only a subset of the constellation points close to the expected symbol value estimated in the previous iteration is proposed. The size of the subset can adapt to the maximum correlation of the sub-matrix after the simple antenna selection. Furthermore, the error rate performance of the scheme under linear Minimum Mean Square Error (MMSE) or Ordered Successive Interference Cancellation (OSIC) for the first run detection and different interleaver lengths is investigated while the transmit antenna selection is considered. The simulation results show a sig- nificant advantage both for implementation complexity and for error rate performance under a fixed data rate.
基金This project was supported by the National Natural Science Foundation of China (60271012)the National High Technology Research and Development Program of China (2006AA12A110).
文摘A simple and efficient design scheme of the continuous long slot leaky-wave antenna is developed. The key steps involved in the scheme are summarized. First, the cut-off frequencies of slot waveguides with different slot offsets are obtained by 3D finite-difference time-domain （FDTD） method, Second, the attenuation function a^a is estimated by the aperture distribution, and the attenuation function αrs is determined by the slot radiation. Finally, the attenuation function αrs is combined with the attenuation function αrs by the coefficient K. And an example in Ka band is presented. Moreover, the return loss of the E-plane Tee-junction （ET） and the radiation pattern of leaky-wave antenna are simulated. The scheme is verified by comparing with the experimental result.
