域F（z）上线性有源网络状态方程的存在性

如何将线性有源网络的每一支路上的物理参量都视为独立参量，那么，网络成了这些参量的有理函数域Ｆ（ｚ）上的网络；本文讨论了这样的网络在Ｆ（ｚ）上状态方程存在的充分条件。由于这条件只与网络的结构有关，因此使用十分简便。     

A HIGH STABLE LONG LIFE-SPAN REFLECTIVE GaAs(Cs,F)PHOTOCATHODE

A stable surface layer is essential for a high stable long life-span photocathode.Byusing fluorine instead of oxygen in activating the surface of GaAs suhstrate,the strongelectronegativity of fluorine may improve the stability of photocathode.Life-span of reflectiveGaAs(Cs,F)photocathode has been made up to 8,500 hours.Furthermore,Its technologicalreproducibility and anti-contamination ability are better than those of GaAs(Cs,O_2)photocathodes.     

基于6LoWPAN的物联网寻址策略研究

在6LoWPAN (IPv6 over Low-power Wireless Personal Area Network)的基础上,该文提出应用于物联网的寻址策略,实现基于IEEE 802.15.4协议的底层异构网络与互联网的实时通信。寻址策略包括IPv6地址自动配置和报头压缩。采用的分层地址自动配置策略,首先在底层网络内部允许节点使用16位短地址导出的链路本地地址进行数据分组传输,该链路本地地址需通过执行基于分簇的重复地址检测机制保证唯一性;其次,每个底层网络中的Sink节点通过上层IP路由器获取全球路由前缀,并与接口标识符相结合,形成Sink节点的全球地址,实现底层网络与互联网的数据交换。同时,通过在报头压缩编码中植入链路本地地址和全球地址控制位,提出了一种适用于物联网应用的报头压缩方案IIPHC (IoTs IPv6 Header Compression)。如果地址类型为链路本地地址,则采用简单灵活的IIPHC1方案,如果地址类型为全球地址,则采用相对复杂但有效的IIPHC2方案。仿真及测试结果表明,基于6LoWPAN的物联网寻址策略在网络开销、时延、吞吐量、能耗等性能方面存在一定的优越性。     

QoS aware traffic grooming and integrated routing on IP over WDM networks

In this article, we consider traffic grooming and integrated routing in IP over WDM networks. The challenges of this problem come from jointly considering traffic grooming, IP routing, and lightpath routing and wavelength assignment (RWA). Due to the high bandwidth of optical fiber, there exists a mismatch between the capacity needed by an IP flow and that provided by a single lightpath. Traffic grooming is therefore used to increase the network utilization by aggregating multiple IP flows in a single lightpath. However, traffic grooming incurs additional delays that might violate Quality-of-Service (QoS) requirements of IP users. In this work, the tradeoff between traffic grooming and IP QoS routing is well-formulated as a mixed integer and linear optimization problem, in which the revenue from successfully provisioning IP paths is to be maximized. Problem constraints include IP QoS, routing, optical RWA, and the WDM network capacity. We propose a novel Lagrangean relaxation (LGR) algorithm to perform constraint relaxation and derive a set of subproblems. The Lagrangean multipliers are used in the proposed algorithm to obtain a solution in consideration of grooming advantage and resource constraints simultaneously. Through numerical experiments and comparisons between the proposed algorithm and a two-phase approach, LGR outperforms the two-phase approach under all experimental cases. In particular, the improvement ratio becomes even more significant when the ratio of IP flow to the wavelength capacity is smaller.     

Construction of LDPC codes over GF（q） with modified progressive edge growth

A parity check matrix construction method for constructing a low-density parity-check (LDPC) codes over GF(q) (q>2) based on the modified progressive edge growth (PEG) algorithm is introduced. First, the nonzero locations of the parity check matrix are selected using the PEG algorithm. Then the nonzero elements are defined by avoiding the definition of subcode. A proof is given to show the good minimum distance property of constructed GF(q)-LDPC codes. Simulations are also presented to illustrate the good error performance of the designed codes.     

有限域上k阶SAC/PC(l)函数的构造

本文给出了有限域F=GF(p~l)上k阶SAC/PC(l)函数的一种构造方法,这种方法不仅是文献[1]中构造方法在有限域上的推广,而且是其一般形式,另外在一定条件下这种函数还可保持平衡性和相关免疫性。最后研究了多输出k阶SAC/PC(l)函数。     

无线传感器网络中基于压缩感知和GM(1,1)的异常检测方案

针对现有的异常事件检测算法准确率低和能量开销较大等问题,该文提出一种基于压缩感知(CS)和GM(1,1) 的异常事件检测方案。首先,基于分簇的思想将传感器节点的数据进行压缩采样后传输至Sink,针对传感器网络中数据稀疏度未知的特点,提出一种基于步长自适应的块稀疏信号重构算法。然后,Sink基于CM(1,1)对节点发生的异常进行预测,并对节点的工作状态进行自适应调整。仿真实验结果表明,相比于其它异常检测算法,该算法的误警率和漏检率较低,在保证异常事件检测可靠性的同时,有效地节省了节点能量。     

WMN多路径路由算法安全性分析与仿真

高效、安全的路由机制是保证无线网状网络(WMN)正常工作的一个重要因素。对WMN中的多径路由(MPR)算法进行了研究。由于MPR算法存在路由分离性约束,提出了一种基于转移概率的随机路由(SR)算法,并对这两种算法进行了仿真。仿真结果表明:在节点转发次数的标准方差和最高截获率两个性能指标方面,SR算法均优于MPR算法,这说明与MPR算法相比,所提算法进一步增强了WMN网络的路由安全性。     

无源光网络中突发光发射机和接收机的设计

本文比较了无源光网络（ＰＯＮ）中突发工作方式的光发射机,接收机与传统的连续工作的光发射机,接收机的差别,分析了春特性,并给出了设计原理图,这些原理图同样适用于其它光纤计算机网络的光发射机,接收机。     

On Least Squares Weighted Recursive Estimation of Clock Skew and Offset in Wireless Sensor Networks

Three clock synchronization algorithms for Wireless sensor networks (WSNs) in Pairwise broadcast synchronization (PBS) mechanism are derived.They include the joint Least squares estimator (LS),joint Least squares weighted estimator (LSW) and joint Least squares weighted Recursive estimator (R-LSW).For these estimators,the corresponding algorithms are derived and described by assuming a Gaussian random delay model.Unlike PBS,these estimators can achieve the Cramer-Rao lower bound (CPLB) for both listening node and active node without knowledge of the deterministic delay.The purpose of considering R-LSW is to reduce the use of storage space with the method of estimating while observing.Simulation and analytical results verify that the estimators are efficient.