网络隧道技术的原理和应用

介绍了网络隧道技术的原理和相关协议.网络隧道是利用封装和加密技术在公共网络中建立的一种虚拟专用连接,实现使用特殊协议的局域网或主机之间的通信,为用户提供安全可靠的服务.隧道技术在虚拟专用网、移动IP、IPv6等方面得到了广泛的应用.     

RCE光电探测器顶部DBR的优化

对研制的 VCSEL 结构外延片制成的谐振腔增强型 (简称 RCE)光电探测器进行了物理分析和实验研究 ,由于 VCSEL 与 RCE光电探测器对谐振腔反射镜的反射率要求不同 ,通过腐蚀 VCSEL 器件顶部 DBR,改变顶镜反射率 ,能够得到量子效率峰值和半宽优化兼容的 RCE光电探测器 ,实现 VCSEL 与 RCE探测器的单片集成 .     

基于数字视频的微细作业系统立体成像方案

分析了现有模拟分时立体成像系统的原理和存在闪烁问题的原因,由于两路CCD信号分时显示使帧频下降,图像存在一定的闪烁感,提出了一种改进的立体成像方案,该方案基于数字视频处理,采用高速的视频解码芯片和DSP芯片,提高了图像显示帧频达到无闪烁立体成像的目的,而且利用插场算法提高了图像的清晰度,有利于对进一步实现视觉跟踪控制或利用视觉信息进行自动控制。     

A gain-clamped SOA with distributed Bragg reflectors fabricated under both ends of active waveguide with different lengths

We demonstrate a gain-clamped semiconductor optical amplifier (GC-SOA) which has gratings under both end regions of an active waveguide. Two gratings of the new GC-SOA are fabricated in different lengths. Their lasing modes and gain characteristics are measured and analyzed with different combinations of grating lengths. It shows different gain and noise characteristics according to the measurement direction in asymmetric grating combinations.     

APT多维度分析和防御研究

“APT多维度分析及防御研究”需要遵循两大原则,即“广谱检测”和“精准定位”的策略。所谓“广谱检测”就是设计的检测方法不局限适用于某一特定的类型的僵尸网络、木马或者蠕虫。“精准定位”就是要求检测结果具有较高的准确性,不仅能确定有无,还要定位感染主机。为了满足上面两个原则,需要将多种检测方法整合到一起,多种检测方法在功能上互相补充,在结果上互相印证,才能获得较理想的结果。     

Study on Characteristics of Various RF Transmission Line Structures on PES Substrate for Application to Flexible MMIC

In this work, the coplanar waveguide is fabricated on a PES (poly[ether sulfone]) substrate for application to a flexible monolithic microwave integrated circuit, and its RF characteristics were thoroughly investigated. The quality factor of the coplanar waveguide on PES is 40.3 at a resonance frequency of 46.7 GHz. A fishbone‐type transmission line (FTTL) structure is also fabricated on the PES substrate, and its RF characteristics are investigated. The wavelength of the FTTL on PES is 5.11 mm at 20 GHz, which is 55% of the conventional coplanar waveguide on PES. Using the FTTL, an impedance transformer is fabricated on PES. The size of the impedance transformer is 0.318 mm × 0.318 mm, which is 69.2% of the size of the transformer fabricated by the conventional coplanar waveguide on PES. The impedance transformer showed return loss values better than –12.9 dB from 5 GHz to 50 GHz and an insertion loss better than –1.13 dB in the same frequency range.     

基于AFT满足下行约束的物理拓扑发现方法

物理拓扑发现对于网络管理和应用具有重要意义,基于地址转发表的物理拓扑发现是目前学术界研究的热点问题.但由于实际网络的地址转发表通常不完整,导致了物理拓扑发现的难度,本文基于降低在实际拓扑发现时对AFT完整性的要求,定义了地址转发表的三类约束,并提出了地址转发表满足下行约束的树型剪裁算法,用于发现子网的物理拓扑结构.算法极大地降低了拓扑发现对地址转发表完整性的要求,是对仅通过下行端口地址转发表进行拓扑发现的最松约束.模拟仿真实验验证了算法的正确性和高效性,算法在实际网管系统中的部署进一步验证了算法在真实网络环境中的实用性.     

Throughput Differentiation and Optimization Via TXOP in IEEE 802.11e EDCA Networks

The Enhanced Distributed Channel Access (EDCA) has been proposed as the mandatory channel access method in IEEE 802.11e to provide Quality-of-Service enhancement. Transmission Opportunity (TXOP) is adopted in the EDCA as one of the service differentiation mechanisms. With the TXOP mechanism, nodes in each Access Category (AC) are allowed to transmit multiple packets for different time intervals after gaining the channel access. Throughput differentiation can then be realized among ACs. The effect of the TXOP mechanism on the performance differentiation was widely studied in previous work. Despite these efforts, it remains largely unknown how the TXOP mechanism affects the optimal network performance. This paper is devoted to study how to achieve the maximum network throughput with the service differentiation requirement via the TXOP mechanism in a saturated IEEE 802.11e EDCA network. In particular, the expressions of both the node throughput and the network throughput are derived as functions of system parameters including the TXOP value in each AC. The node-throughput ratio is determined by TXOP values, which validates that the TXOP mechanism is effective in providing throughput differentiation. The explicit expression of the maximum throughput is further derived, and is found to be determined by the TXOP mechanism and the service differentiation requirement of each AC. To achieve the maximum throughput, the initial backoff window size of each AC should be adaptively chosen according to the TXOP values, the targeted node-throughput ratios as well as the number of nodes in each AC.     

基于SE-Workbench-IR的红外视景仿真研究

随着仿真技术的发展,红外视景仿真在军事领域的作用和带来的效益日益突出.为拓展红外视景仿真的研究手段,文中介绍了一个先进的红外视景仿真平台--SE-Workbench-IR,并在此基础上对基于SE-Workbench-IR的红外视景仿真方法及其应用进行了研究.结果表明,SE-Workbench-IR可以实现高逼真度和多波段的红外视景仿真.     

移动回传的融合之路

在介绍移动网络发展趋势的基础上,从固定与移动的融合、多种接入方式的融合等方面阐述了移动回传融合的历程,并对IP RAN回程技术进行了比较,最后给出了阿尔卡特朗讯移动回程解决方案。