认知OFDM系统中针对视频业务用户的资源分配方案

在多用户认知无线电OFDM系统中,针对实时视频业务用户,本文提出一种计算复杂度低的资源分配方案。该方案采用鱼群算法分配子载波,并提出简单功率干扰(Simple Power Interference, SPI)约束功率分配算法。目标是在满足总功率预算并且保证不干扰主用户的前提下,最大化系统的下行系统容量。仿真分析表明,在视频业务用户场景中,本文所提算法能有效提高下行系统速率,性能接近最优且复杂度低。     

基于正交空分复用的多用户调度策略

为了消除多用户MIMO下行系统的多用户间干扰以及改进系统的误码率性能,研究了块对角化预编码与几何均值分解的联合方案(BD-GMD).针对BD-GMD系统的资源分配和用户调度,对比了等功率分配和注水算法对系统的影响,并基于系统容量最大化,提出了一种根据用户信道的子空间特性的低复杂度的用户调度算法.此外,对比分析了穷举搜索算法和传统的贪婪算法.数值仿真结果表明,文中所提出的基于正交投影的多用户调度算法充在保证系统容量的同时降低了算法复杂度.     

一种多用户MIMO/OFDM下行链路保障QoS的自适应传输机制

在用户QoS参数限制下,该文提出一种在多用户MIMO/OFDM下行链路使系统总速率最大的资源分配机制。基站应用空分多址接入,使得每个子载波可支持多个用户,应用线性预编码方法抵消用户间的干扰,提出保障QoS的自适应功率、比特分配方案。该文并提出两种可应用到实际系统的低复杂度的比特加载和比特去除算法,仿真结果表明,该两种方法性能可非常接近最优遍历算法。     

多载波超密集网络的抗干扰分布式节能功率分配

该文研究多载波超密集网络(UDN)上行链路能效最优功率分配方案,基于非合作博弈论提出一种抗干扰分布式功率分配方案,使每个小区独立优化能效的同时抑制邻小区干扰.由于最大传输功率和QoS约束下的能效函数具有不易解决的非凸特性,且小小区间存在严重干扰.针对以上挑战,该文在最佳响应过程中设计了一种高精度低复杂度的阶梯注水算法,基于该算法利用干扰信道增益提出了一种多用户抗干扰功率分配算法.仿真结果和数值分析表明该算法运算复杂度低,且能在保证系统频谱效率的同时大幅度提升系统能效.     

多用户MIMO—OFDM系统低复杂度资源分配算法研究

在MIMO-OFDM系统下行链路下提出了一种低复杂度的子载波和功率分配算法,为了在满足用户QoS需求的情况下,最小化用户的发射功率,本文算法将子载波分配给在所有子信道上具有最大增益的用户。仿真结果显示所提算法在复杂度和性能都优于以前的算法。     

不完整CSI下OFDMA无线中继系统资源分配算法研究

针对实际OFDMA系统中下行无线链路信道状态信息(CSI)不完善的前提下,提出一种满足不同用户QoS需求的资源分配算法。在该方案中,首先确定用户与中继站之间的CSI,然后在总功率约束条件下,通过在等功率分配降低算法复杂度的基础上进行最佳中继选择和子载波的分配,最后再对子载波进行注水的功率分配来进一步提高系统容量。仿真结果表明,该方案在保证用户QoS的同时进一步提高系统容量。     

基于公平性的多用户OFDM系统自适应功率分配松弛算法

提出了两种多用户OFDM系统下行链路的自适应功率分配算法.通过进一步放松不同用户之间数据速率比例性要求,提出的新算法提高了功率使用效率.实验仿真表明:在降低计算复杂度的同时,大大提高了系统容量,并且也近似满足了不同用户之间数据速率比例性要求.     

多载波超密集网络的抗干扰分布式节能功率分配

该文研究多载波超密集网络(UDN)上行链路能效最优功率分配方案,基于非合作博弈论提出一种抗干扰分布式功率分配方案,使每个小区独立优化能效的同时抑制邻小区干扰。由于最大传输功率和QoS约束下的能效函数具有不易解决的非凸特性,且小小区间存在严重干扰。针对以上挑战,该文在最佳响应过程中设计了一种高精度低复杂度的阶梯注水算法,基于该算法利用干扰信道增益提出了一种多用户抗干扰功率分配算法。仿真结果和数值分析表明该算法运算复杂度低,且能在保证系统频谱效率的同时大幅度提升系统能效。     

多用户MIMO-OFDM系统中的一种新的用户调度算法

本文针对多用户环境下的多天线正交频分复用下行系统,提出了一种新的基于迫零波束成型的用户调度算法。迫零波束成型是在发送端消除用户间的干扰生成多个独立的空间子信道,来实现空间复用。由于在多天线正交频分复用下行系统中最优的用户选择算法需要遍历所有可能的用户集合,算法复杂度非常大,本文提出了一种简化算法。所提算法在保证每个用户的速率要求的情况下,通过贪婪算法来选择每个子载波上的用户集合,以最小化系统的发送功率。仿真结果表明在满足用户的速率要求下能达到很好的系统性能。     

基于智能反射面的无线抗干扰通信方法

由于无线信道的开放性,当前无线通信系统愈发受到恶意干扰攻击. 为了提高无线通信干扰能力,提出了一种基于智能反射面（intelligent reflecting surface, IRS）的抗干扰通信方法. 针对IRS辅助的通信抗干扰系统,考虑在用户接收信干噪比约束和连续相移约束下,建立非线性、多变量耦合的功率最小化资源分配模型,以实现频谱和能量性能的双向提升. 利用交替优化和半正定松弛求解原变量耦合的非凸优化问题,以得到最优发射波束和IRS相移. 此外,针对模型求解复杂度高的问题,还提出了一种低复杂度算法以得到发射波束的低复杂度闭式解. 同时,进一步提出了一种实用且快速响应的经验算法,以应对时变高动态干扰. 仿真结果表明,与现有未引入IRS方案相比,所提算法在各种情况下收敛迅速,并且功率消耗和干扰容限都有约30 dB的性能提升.     

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.     

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.     

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.     

Technology innovation and process integrations for sub-100nm gate patterning

This paper presents a brief overview of the Applied Centura(R)DPS(R)system,configured with silicon etch DPS Ⅱ chamber, with emphasis on discussing tuning capability for CD uniformity control. It also presents the studies of etch process chemistry and film integration impact for an overall successful gate patterning development. Discussions will focus on resolutions to key issues, such as CD uniformity, line-edge roughness, and multilayer film etching integration.     

White organic light-emitting devices based on fac tris（2- phenylpyridine） iridium sensitized 5,6,11,12-tetraphenylnap -hthacene

We have fabricated the white organic light-emitting devices （WOLEDs） based on 4,4＇ -bis（2,2 -diphenyl vinyl）-1,1＇ - biphenyl （DPVBi） and phosphorescence sensitized 5,6,11,12,-tetraphenylnaphthacene （rubrene）. The device structure is ITO/2T-NATA （20 nm）/NPBX （20 nm）/CBP： x%Ir（ppy）3：0.5% rubrene （8 nm）/NPBX （5 nm）/DPVBi （30 nm）/Alq（30 nm）/LiF（0.5 nm）/A1. In the devices, DPVBi acts as a blue light-emitting layer, the rubrene is sensitized by a phosphorescent material, fac tris （2-phenylpyridine） iridium [Ir（ppy）3], acts as a yellow light-emitting layer, and N,N＇ -bis- （1-naphthyl）- N,N＇ -diphenyl -1, 1＇ -biphenyl-4,4＇ -diamine （NPBX） acts as a hole transporting and exciton blocker layer, respectively. When the concentration of Ir （PPY）3 is 6wt%, the maximum luminance is 24960 cd/m^2 at an applied voltage of 15 V, and the maximum luminous efficiency is 5.17 cd/A at an applied voltage of 8 V.     

Complete approach to automatic identification and subpixel center location for ellipse feature

To meet the need of automatic image features extraction with high precision in visual inspection, a complete approach to automatic identification and sub-pixel center location for similar-ellipse feature is proposed. In the method, the feature area is identified automatically based on the edge attribute, and the sub-pixel center location is accomplished with the leastsquare algorithm. It shows that the method is valid, practical, and has high precision by experiment. Meanwhile this method can meet the need of instrumentation of visual inspection because of easy realization and without man-machine interaction.     

小角度扩展相关性近似算法分析

本论文提出一种在多天线MIMO信道相关性建模中小角度扩展近似理论算法,并应用于分析MIMO系统性能。分析中分别对三种不同角能量分布情况下的空间相关性研发快速近似计算法,并同时提出双模(Bi-Modal)角能量分布情况下的近似运算。通过分析这些新方法的近似效率,可以得到计算简单、复杂度低、而且符合实际的MIMO相关信道矩阵,对系统级的快速高效计算法的研究和系统级的评估以及误差分析具有重要的意义。     

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.