基于块空时分组编码虚拟MIMO中继传输方案

以LTE TDD系统上行链路为研究对象,提出了一种基于块空时分组编码的虚拟MIMO中继传输方案,并推导给出基站低复杂度的虚拟MIMO系统接收机检测算法。研究表明:本传输方案具有提高小区边缘及网络覆盖盲区用户链路传输可靠性的特性,同时可克服传统中继方案频谱效率降低的缺点。     

基于块空时分组编码DFT-S-OFDM虚拟MIMO传输方案

该文提出了一种基于块空时分组编码的DFT-S-OFDM上行链路虚拟MIMO传输方案,并给出一种低复杂度的虚拟MIMO系统接收机检测算法。仿真研究表明:基于块空时分组编码的DFT-S-OFDM虚拟MIMO传输方案可保持原DFT-S-OFDM系统低峰均比的特性,显著降低虚拟MIMO系统接收机检测门限,提高上行链路虚拟MIMO系统传输可靠性。     

TG分流提升TD-SCDMA网络利用率

三大TG分流措施提升TD-SCDMA网络利用率：适当提升PCCPCH功率改善TD覆盖。23G互操作参数精细优化,使用户尽量驻留在TD。采用新技术,保证客户感知,引入基于IMEI的分组切换算法和基于上行链路质量的切换算法两项新技术。     

无蜂窝大规模MIMO中基于深度强化学习的无人机辅助通信与资源调度

无蜂窝大规模多入多出(MIMO)网络中分布式接入点(AP)同时服务多个用户,可以实现较大区域内虚拟MIMO的大容量传输;而无人机辅助通信能够为该目标区域热点或边缘用户提供覆盖增强.为了降低反馈链路负载,并有效提升无人机辅助通信的频谱利用率,该文研究了基于AP功率分配、无人机服务区选择和接入用户选择的联合调度;首先将AP...     

基于时延感知的5G通信链路映射算法

现有5G通信算法存在兼容性差,误码率高等问题,导致数据传输频谱效率和峰值速率较低。因此提出基于时延感知的5G通信链路映射算法。该算法通过线性预编码技术传输数据,对数据预先处理,进而设计5G通信链路的层映射模式,完成数据到端口的处理,最后基于时延感知优化映射算法感知层,实现对5G通信链路映射算法的优化。实验结果表明,与传统算法相比,数据传输的频谱效率和峰值速率均有所提升,总体数据传输效果提升19.8%。由此可见,基于时延感知的5G通信链路映射算法具有更高效的数据传输效果。     

大规模MIMO无线专网下行链路检测算法研究

以充分开发利用大规模多输入多输出(Multiple-Input Multiple-Output,MIMO)空间上的无线资源、提升系统频谱效率和功率效率为目标,在充分分析无线专网信道特点的基础上,提出了线性检测和非线性检测2种方案,将多级预编码和检测算法有机结合,对高斯、乡村、市区及山区等信道条件下的误码性能和吞吐量进行了仿真分析,验证了球形译码算法优于MMSE检测算法,适用于基于大规模MIMO无线通信专网下行链路高性能接收机。     

基于RANK多流智能预测的5G速率优化方法研究

为了应对5G RANK无法精准高效优化的技术难题，本文提出了一种基于RANK多流智能预测的5G速率优化方法。该方法通过建立传播模型和MIMO信道模型挖掘网络多径环境，实现RANK精准预测，采用聚类算法识别RANK提升的高潜力区域，以多维综合增益最优为目标，利用投票算法和主服小区建模算法输出RANK优化方案，使用户可获得最大的网络多流能力，大幅提升不同覆盖场景下的5G用户速率。     

提升4G网络质量的几种手段

4G网络经历了多年大规模建设后进入网络优化调整阶段,网络质量不佳的主要原因是覆盖不足及重叠覆盖引起的干扰。对此,文章提出几种提升网络质量的技术应用。在覆盖不足方面,通过4T4R(4发4收)技术提升频谱效率,加强网络深度覆盖;通过TTI Bund-ing(时隙绑定)技术提高上行边缘覆盖水平。在干扰控制方面,利用UL CoMP(上行多点协同)技术改善上行网络质量;应用ASFN(自适应单频网)技术改善下行网络质量;采用高阶调制解调技术提升上下行速率。     

基于LTE测量报告的2.1 GHz和3.5 GHz 5G SA覆盖评估方法

2.1 GHz频段重耕是城区5G网络部署需要研究的重要课题。分析了仿真预测网络覆盖存在的缺陷。考虑绝大部分5G基站与LTE同址并采用相同或相似工参的情况,提出了基于LTE测量报告的2.1 GHz和3.5 GHz 5G SA覆盖评估方法。该方法首先建立同址2.1 GHz和3.5 GHz 5G SA覆盖差异模型并通过测试验证其准确性,然后根据LTE测量报告、覆盖差异模型及速率与链路损耗关系评估两个频段的覆盖质量。评估实例表明,因城区LTE网络覆盖具有10 dB余量,同址20 MHz带宽内的2.1 GHz 5G重耕仅在1～10 Mbit/s上行速率覆盖率较3.5 GHz有1.3～5.2个百分点的增益。     

认知网络中的多用户MIMO线性协作频谱感知问题研究

研究了多用户MIMO的线性协作频谱感知问题以提高频谱检测的可靠性,推导了多用户MIMO线性协作感知系统的局部检测和全局检测策略,建立了在给定误警概率的情况下控制中心通过优化给各个用户的信号所分配的权值来最大化全局检测概率的优化模型。进一步,引入了遗传算法来求解上述全局检测优化问题的最优权值,期望能够有效降低算法在频谱感知过程中检测时间。仿真结果表明,多入多出能够明显提高协作频谱感知系统频谱检测可靠性,而遗传算法高效且稳定,相比较其他算法能够有效改善系统的检测性能。     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

中国建立EB级存储实验室,致力云计算应用(英文)

正With the support of 863 programs,Sugon Information Industry Co.,Ltd.,set up a dawning EB-class storage laboratory to address massive data storage requirements and largescale cloud computing demonstration applications.The Dawning EB-class cloud storage system adopts advanced fault-tolerant architecture,efficient data fault-tolerant algorithms with user authentication and data encryption policies to deal with the"lost""wrong"and"stolen"problems of data for ensuring the reliability and safety of the EB-class storage system in the public network application environments.The Dawning EB-class Storage Laboratory taking advan-