PHS系统及其关键技术发展趋势

介绍了PHS系统结构以及相关技术特点;在此基础上,对PHS手机终端,基站信号处理技术和核心网络的发展与演进等方面进行了介绍与探讨。     

Comparison between the Spectral Efficiency of SDMA Systems and Sectorized Systems

In this paper we present a comparison of the spectral efficiency of Spatial Division Multiple Access systems with conventional omni-directional and sectorized systems. Our analysis attempts to incorporate the effect of co-channel interference (CCI) for users sharing the same channel within a cell (intra-cell interference) as well as the CCI from other cells (inter-cell interference). To determine the outage probability we utilize exact results for combined Rayleigh and Log-normal shadowing in conjunction with a generic antenna pattern. The study is limited to the forward link only and the switched-beam approach. Results are provided for the outage probability and spectral efficiency for various reuse distances and blocking probabilities. These demonstrate that under most conditions, SDMA systems have higher spectral efficiency than conventional omni-directional or sectored systems. Nevertheless under certain conditions such as high blocking probabilities or large reuse distances, the spectral efficiency of SDMA systems is lower than conventional systems.     

Narrow and wide band monopole antenna design using heterogeneous bidirectional recurrent neural network for LTE and UWB applications

The proposed antenna is a small wideband monopole with wideband circular polarization using heterogeneous bidirectional recurrent neural network for both narrow and wide band applications (NWB-MAD-HBRNN). The electromagnetic structure is designed, fabricated, and simulated with 1 mm thickness on FR4 substrate material along dielectric constant 4.3. The proposed antenna includes 4.3–8.85 GHz for ultrawideband applications; it contains reconfigurable narrow band for L-band 1.27 GHz, LTE, and ultrawideband applications. To enhance the antenna impedance bandwidth (BW) along axial ratio bandwidth (ARBW), a slit is etched at the antenna patch, a rectangular stub is inserted into the ground plane, and semicircular stub is added to the top of antenna feed line. The better agreement is observed in the measured and simulated gain performance of 4.8 dB for LTE band applications. The proposed NWB-MAD-HBRNN design provides 13.50%, 18.91%, and 22.58% higher bandwidth and 18.36%, 20.38%, and 27.58% lower return loss than the existing designs, such as bio-inspired wideband antenna for wireless applications based on perturbation technique (BWA-WA-PA), a compact circularly polarized modified printed monopole antenna for wireless applications (CCP-MPMA-WA), and new multiband monopole antenna for certain broadband wireless applications along wireless personal communications (PA-MMA-BWA), respectively.     

基于特征空间的MIMO天线选择算法

多输入多输出(MIMO)系统中多天线阵元(MEA)的使用增加了硬件成本和信号处理负担,而天线选择技术能够在损失MIMO性能很小的条件下大幅度降低硬件需求.在最大化信道容量的准则下,提出了一种基于信道状态信息(CSI)特征空间的渐消算法及相应的启发式简化算法,并说明了简化算法等价于特征空间矩阵上的基于范数的选择(NBS)算法.仿真实验表明,在接收天线选择个数大于发送天线个数的条件下,两种算法达到的中断容量接近最优选择算法,且计算时间较小.     

相对论核多体理论中的自洽问题和求和规则

着重讨论了建立在相对论平均场基态上的相对论无规位相近似的自洽处理 .自洽处理要求基态和巨共振激发态的研究从同一个拉氏量出发,采用同一种建立在相对论下的完备基上的近似 .同时也讨论了自洽条件下Dirac海核子态的作用 ,指出 Dirac海核子态的贡献不能忽略 ,特别是在核的巨单极共振的情况.用约束的相对论平均场方法得到核的巨单极共振的能量逆权重的求和规则 ,从数值上验证了 Dirac海核子态的贡献. A consistent treatment is extremely important in relativistic approaches. We emphasized the consistent approach in relativistic random phase approximation built on relativistic mean filed ground states. The consistent treatment requires that the studies of the ground state and excited states of giant resonances are based on same effective Lagrangian, and on a same complete set of basis. It was found that the effect of the Dirac states could not be neglected, especially in the case of giant...     

Performance of Adaptive Antennas in FH-GSM Using Conventional Beamforming

This paper presents the performance of adaptiveantennas in a 1/3 reuse frequency hopping GSM networkusing conventional beamforming. It mainlyfocuses on C/I improvement for the purpose of capacityenhancement. The performance evaluation has beenconducted by means of network computer simulations,where measured time-space radio channel impulseresponses are applied for the desired user in thenetwork. Measurements with an M = 8 element uniformlinear array were conducted in the cities ofAarhus, Denmark, and Stockholm, Sweden. The simulatedC/I improvement shows an almost 10 * log₁₀(M)behavior for low azimuth spread values. For largevalues of azimuth spread (relative to the antennabeamwidth), the performance gain is reducedsignificantly. For an azimuth spread of10°–12°, which has been measured inurban macro-cellular environments, the C/I gain forM = 8 is reduced to approx. 5.5–7.5 dB (which should becompared to the theoretical value of 9 dB for a pointsource). The designed DoA algorithm is very robust toco-channel interference and only a small degradationin performance is observed for single element C/I downto approx. –8 dB. We conclude that the designedbeamforming implementation facilitates a potentialcapacity gain of ×3 in a 1/3 reuse FH-GSM network foran array size of M = 4–6.     

一种新型毫米波馈电系统

介绍一种新型开放式毫米波馈电系统－－超导准光系统,该系统已成功地应用于我国１３．７ｍ口径毫米波望远镜上,它工作于２．６ｍｍ波段,已成功进行天文实测和天文研究工作。该系统应用了一个新型４Ｋ低温致冷系统,可工作于二个频段。文中详细介绍了该系统的设计理论及研制结果。实测结果表明,整个系统的插损在２．６ｍｍ波段仅０．１ｄＢ,这种损耗比起波导系统而言是极其微小的,接收机的系统噪声温度在８５ＧＨｚ￣１１２ＧＨ     

Model Scenarios for Direction-Selective Adaptive Antennas in Cellular Mobile Communication Systems – Scanning the Literature

Intelligent antennas offer the possibility of greatly increasing the capacity of cellular mobile radio systems. We give a comprehensive overview of the literature concerning model scenarios for applications of direction-selective intelligent antennas. Measurement campaigns and simplified models are described that have been derived from these measurements or from physical considerations. Furthermore, directional fading simulators are reviewed which are essential for testing of smart antenna systems.     

实用套筒天线宽带特性研究

本文采用Fourier变换的方法,给出了分析套筒天线的通用程序;系统研究了各参变量对天线阻抗特性的影响并给出了相应的曲线。在此基础上,总结出一种行之有效的理论设计和实验调整方法并利用此法设计了实用的工作于40MHz～88MHz的套筒天线。理论结果与实验测试相吻合。     

移动通信中多波束智能天线性能的研究

研究了移动通信环境下的多波束智能天线,并基于统计传播的同信道干扰模型,分析了快衰落及慢衰落情况下未采用多波束智能天线与采用多波束智能天线时的中断率,并进行了比较.计算机仿真结果表明采用多波束智能天线,不论在单个同信道小区还是多个同信道小区情况下,系统的中断率将随着波束数的增大而降低.