基于动态树冲突分解的协作随机接入方案

提出一种基于动态树冲突分解的协作随机接入方案(DTCRA)。该方案设置一个由冲突节点个数决定的信道增益门限值,若源节点与接入点间的信道增益大于该门限值,则源节点重传数据包,否则由中继节点放大转发,从而实现了动态树冲突分解,获得了多用户分集增益并降低了空时隙数量。数值与仿真结果表明,提出的方案相比于其它传统类和跨层类随机接入方案,具有更好的吞吐量、时延和能量效率性能。     

一种惩罚非适应流的无状态主动队列管理算法

CHOKe是一种无状态的主动队列管理算法,能以较低的代价提高网络的性能,但是由于它对超速的非适应流的惩罚力度不够,不能够很好地实现带宽的公平分配。针对这一问题,提出一种新的对非适应流的惩罚机制-ECHOKe算法,通过比较分析FIFO队列中随机抽取m个包与新到包的流ID号之间的关系以及m个包之间的关系建立了新的数据包丢弃机制,从而实现在不提高算法复杂度的前提下增大对超速非适应流的惩罚,提高了公平性。仿真结果表明,在不保持流的状态下,该机制对非适应流具有更强的识别和控制能力,与B-CHOKe和M-CHOKe算法相比,能够进一步加强对非适应流的惩罚,实现更为公平的带宽分配。     

基于冗余避免的高效网络编码广播重传方法

为了提高无线网络中基于网络编码的广播重传方法的编码效率,从而有效地减少重传次数和数据包传输时延,提出一种主动避免编码冗余的高效网络编码广播重传方法(network coding broadcasting retransmission approach based on redundancy avoiding,NCRA)。NCRA编码时主动避免不能解码的编码组合被重复编码重传,同时优先编码重传对接收节点已缓存的未解码编码包的解码贡献较大的丢失数据包以充分利用编码机会,在对解码贡献相同的条件下优先编码较早丢失的数据包以减小数据包传输时延。理论分析和仿真结果表明,NCRA算法相比于现有算法能有效减小重传次数和降低数据包传输时延,减少网络开销,进一步提高了编码重传的效率。     

基于存储机制的LT码编译码方法

提出一种基于存储(memory based, MB)机制的Luby变换码的编译码方法,来实现信息在二进制删除信道(binary erasure channel, BEC)中的可靠传输。首先,发送端的编码器采用泊松鲁棒孤子分布(Poisson robust soliton distribution, PRSD)产生普通编码包,同时产生携带存储信息的“存储包”。然后,源源不断在BEC中发送编码包和“存储包”给接收端。接收端的译码器根据接收到的“存储包”的数量不同,采取不同方式对输入包进行译码。如果“存储包”全部被接收,则所有输入包都能通过“存储包”中的存储信息直接获得;如果部分“存储包”丢失,则结合“存储包”和置信传播(beliefpropagation, BP)算法进行译码;如果所有“存储包”丢失,则仅采用BP算法进行译码。仿真结果表明,相比LT码的传统编译码方法,采用PRSD MB方法可以大大降低误比特率,提高编译码效率。     

End-to-end rate-based congestion control with random loss: convergence and stability

The convergence and stability analysis for two end-to-end rate-based congestion control algorithms with unavoidable random loss in packets are presented, which can be caused by, for example, errors on wireless links. The convergence rates of these two algorithms are analyzed by linearizing them around their equilibrium points, since they are globally stable and can converge to their unique equilibrium points. Some sufficient conditions for local stability in the presence of round-trip delay are obtained based on the general Nyquist criterion of stability. The stability conditions can be considered to be more general. If random loss in the first congestion control algorithm is not considered, they reduce to the local stability conditions which have been obtained in some literatures. Furthermore, sufficient conditions for local stability of a new congestion control algorithm have also been obtained if random loss is not considered in the second congestion control algorithm.     

基于单反馈SLT码的纠错码与MP联合译码

转移LT(shifted Luby transform,SLT)码是信源依据接收端的反馈信息进行的LT(Luby transform,LT)编码方法,这种编码方法可以有效地减少解码所需要的数据包个数,由此,本文针对基于单次反馈SLT码的信道纠错码与信息传递(message propagation,MP)联合译码方法,对原有的转移鲁棒孤立子分布(shifted robust soliton distribution,SRSD)函数进行改进得到适合MP联合译码的扩展转移鲁棒孤立子分布(expand shifted robust soliton distribution,ESRSD)函数。将本文提出的ESRSD用于MP联合译码方案分别与LT码、反馈SRSD MP联合译码相比,实验结果显示,采用本文提出的ESRSD进行编码在MP译码所需要数据包的个数最少。     

Fuzzy Views on Black-Litterman Portfolio Selection Model

In this paper, views of investor are described in fuzzy sets, and two fuzzy Black-Litterman models are constructed with fuzzy views and fuzzy random views respectively. In the models, expected returns and uncertainty matrix of views are redefined and the views are formulated by fuzzy approaches suitably. Then the models are tested with data from Chinese financial markets. Empirical results show that the fuzzy random views model performs the best, and both the fuzzy models are better than the traditional ones, demonstrating that the fuzzy approaches can contain more information in the views and measure the uncertainty more correctly.     

基于链路通信效率的高能效路由转发策略

无线传感器网络使用短距离无线通信技术实现节点间的数据通信,该技术的物理特性决定了网络的真实链路行为具有较大的随机性,这种随机性往往导致网络数据丢包,并影响路由转发的性能表现。针对这个问题,在有损链路模型下深入分析了链路通信效率,总结出一维线性网络整体通信效率与包接收率、链路通信距离之间的关系,基于此,提出一种以链路通信效率为转发依据的高能效路由转发策略。通过仿真实验验证该策略在有损通信链路下有更好的能效性和鲁棒性。     

BCH编码对蓝牙数据传输性能改善的分析与仿真

提出了在蓝牙2．0＋EDR新规范中加入采用BCH编码的数据分组，以有效地提高蓝牙的数据传输速率以及抗干扰能力；根据蓝牙标准协议对数据包的定义推导出了新增数据分组的分组特性；分析了在AWGN信道下原有的DH分组和新采用BCH编码数据分组的数据重传概率与平均接收信噪比的关系，并且计算出了各个数据分组在不同信噪比的情况下数据传输吞吐量。仿真结果表面，在蓝牙2．0＋EDR新规范中采用BCH编码方式，明显地改善了数据传输的抗干扰能力、有效地提高了在AWGN信道下的数据传输吞吐量。     

网络安全研究中的建模环境分析与实现

提出网络建模环境的形式化描述,据此将网络模型划分为三种虚拟度,并结合网络安全研究特点提出了具备三种虚拟度的高保真建模概念。在网络模拟器NS2基础上实现了一个原型系统,并阐述和分析了其结构、实现与性能,还给出一个支持真实攻击包的蠕虫模型实例。最后分别对若干问题和未来工作进行了总结与展望。     

Flooding attack and defence in Ad hoc networks

1 .INTRODUCTIONMobile Ad hoc Network is an autonomous system ofmobile nodes connected by wirelesslinks .It has sever-al salient characteristics ,such as Dynamic topologies ,Bandwidth-constrained,variable capacity links , Ener-gy-constrained operation,Li mited physical security[1].Due tothesefeatures ,mobile ad hoc networks are par-ticularly vulnerable to denial of service attackslaunchedthrough compromised node.In this paper , we present a new attack,theAd hoc Flooding Attack, which re…     

基于随机行走介数的级联失效模型

将随机行走介数引入级联失效模型,提出了基于随机行走介数的级联失效模型,该模型较基于介数的级联失效模型更加符合实际情况。为了研究该模型的特性,针对无标度网络和随机网络,运用仿真方法,将其与基于介数的级联失效模型进行了比较。通过对两组共4个无标度网络模型和两个随机网络模型的仿真,发现基于随机行走介数的级联失效模型的节点介数相对较小,不同节点间介数大小的差距也较小,并分析了得到上述仿真结果的原因。     

GENERALIZED p-VALUES AND GENERALIZED CONFIDENCE INTERVALS FOR VARIANCE COMPONENTS IN GENERAL RANDOM EFFECT MODEL WITH BALANCED DATA

Various random models with balanced data that are relevant for analyzing practical test data are described, along with several hypothesis testing and interval estimation problems concerning variance components. In this paper, we mainly consider these problems in general random effect model with balanced data. Exact tests and confidence intervals for a single variance component corresponding to random effect are developed by using generalized p-values and generalized confidence intervals. The resulting procedures are easy to compute and are applicable to small samples. Exact tests and confidence intervals are also established for comparing the random-effects variance components and the sum of random-effects variance components in two independent general random effect models with balanced data. Furthermore, we investigate the statistical properties of the resulting tests. Finally, some simulation results on the type Ⅰ error probability and power of the proposed test are reported. The simulation results indicate that exact test is extremely satisfactory for controlling type Ⅰ error probability.     

基于自适应矢量压缩的机会网络高效低时延路由算法

针对采用epidemic机制的机会网络路由算法在汇总矢量(summary vector, SV)的交换、存储和请求矢量(request vector, RV)的交换过程中存在冗余开销影响效率的问题,提出一种基于自适应矢量压缩的路由算法（epidemic routing based on adaptive compression of vector, ERACV）,所提算法通过采用自适应压缩SV和RV的长度、改进SV交换、收到SV分组后优先发送目的地为相遇节点的数据分组等新机制,减少控制开销和节点的存储开销,降低数据分组时延。理论分析验证了ERACV算法的有效性,仿真结果显示,与经典的感染路由算法分销及其改进后的消息传输控制算法相比,ERACV算法的控制和SV存储开销分别减少了39% 和96.4%,数据分组的平均端到端时延则降低了2.5%以上,并且维持了100%的数据传送成功率。     

MCHOKeM algorithm with assured bandwidth allocation in DiffServ networks

An active queue management (AQM) algorithm called MCHOKeM is presented, which is borrowed from CHOKeW that draws multi-packets at random from the buffer, the multi-packets are compared with an arriving packet and abandoned if they are from the same flow. But MCHOKeM uses multiple virtual queues for different priority packets and enhances the drawing function by adjusting the maximum number of draws based on the current status of virtual queue length. The number of parameters that MCHOKeM needs to maintain is determined by the number of priority levels being supported by the router, which usually has a small limited value. In order to explain the features of MCHOKeM, an analytical model is used. A series of simulation tests to evaluate the performance are given.     

Robust data envelopment analysis based MCDM with the consideration of uncertain data

The application of data envelopment analysis (DEA) as a multiple criteria decision making (MCDM) technique has been gaining more and more attention in recent research. In the practice of applying DEA approach, the appearance of uncertainties on input and output data of decision making unit (DMU) might make the nominal solution infeasible and lead to the efficiency scores meaningless from practical view. This paper analyzes the impact of data uncertainty on the evaluation results of DEA, and proposes several robust DEA models based on the adaptation of recently developed robust optimization approaches, which would be immune against input and output data uncertainties. The robust DEA models developed are based on input-oriented and outputoriented CCR model, respectively, when the uncertainties appear in output data and input data separately. Furthermore, the robust DEA models could deal with random symmetric uncertainty and unknown-but-bounded uncertainty, in both of which the distributions of the random data entries are permitted to be unknown. The robust DEA models are implemented in a numerical example and the efficiency scores and rankings of these models are compared. The results indicate that the robust DEA approach could be a more reliable method for efficiency evaluation and ranking in MCDM problems.     

异类传感器多目标检测跟踪与识别随机集模型

为在空中预警监视系统中实现多异类传感器多目标联合检测、跟踪与识别,在多目标检测、跟踪的随机有限集模型基础上,进行多异类传感器多目标联合检测、跟踪与识别的理论模型与处理框架研究。通过对目标的运动学状态与目标识别属性状态统一描述,把多目标状态建模为一个用随机有限集描述的全局状态。通过对运动学传感器与属性传感器模型分析,把各异类传感器建模为一个全局传感器,并把各传感器的测量建模为一个用随机有限集描述的全局测量。根据全局状态与全局测量模型,把异类传感器多目标联合检测、跟踪与识别过程描述为Bayes滤波过程,并给出了相应的多异类传感器多目标联合检测、跟踪与识别处理框架。通过仿真试验验证了理论模型与框架的有效性。     

退化系统状态维修决策与维修活动建模

研究退化系统的状态维修决策问题,考虑经济性、可用性后,给出两个通用维修决策优化模型,用gamma过程对系统退化进行建模,用监测数据估计退化模型参数。在退化过程基础上,基于历史维修信息和状态数据对决策模型中的变量进行确定;对维修活动中主要的影响--维修效果和维修时间进行分析,认为维修效果和维修时间是系统状态和维修次数的随机变量,分别给出了不考虑人为因素和考虑人为因素的维修效果几何分布模型,用插值方法建立维修时间分布函数。最后以某控制系统为例,对比理想状态和考虑维修效果与维修时间下的仿真结果,验证了模型的有效性和实用性。     

级联码中的高码率短码长SLT码设计

将SLT（system Luby transform）码,尤其是高码率短码长的SLT码与低密度校验（low density parity check, LDPC）码等信道纠错码级联,可以通过增加少量的译码开销来有效地提高译码增益。然而,基于传统的设计方法得到的编码包度数分布难以保证在这种情况下得到性能良好的码字。结合级联译码的场景,在传统的优化方法基础上,增加了对编码包度数分布的优化,同时改进了具体的构造方法,从而给出了一种高码率短码长的SLT码的设计方法。仿真结果显示,新方法设计的码字能够取得良好的性能。     

Strong Law of Large Numbers for Weighted Sums of Random Variables and Its Applications in EV Regression Models

This paper mainly studies the strong convergence properties for weighted sums of extended negatively dependent(END, for short) random variables. Some sufficient conditions to prove the strong law of large numbers for weighted sums of END random variables are provided. In particular, the authors obtain the weighted version of Kolmogorov type strong law of large numbers for END random variables as a product. The results that the authors obtained generalize the corresponding ones for independent ra...