Cooperative Channel and Optimized Route Selection in Adhoc Network

Over the last decade,mobile Adhoc networks have expanded dramati-cally in popularity,and their impact on the communication sector on a variety of levels is enormous.Its uses have expanded in lockstep with its growth.Due to its instability in usage and the fact that numerous nodes communicate data concur-rently,adequate channel and forwarder selection is essential.In this proposed design for a Cognitive Radio Cognitive Network(CRCN),we gain the confidence of each forwarding node by contacting one-hop and second level nodes,obtaining reports from them,and selecting the forwarder appropriately with the use of an optimization technique.At that point,we concentrate our efforts on their channel,selection,and lastly,the transmission of data packets via the designated forwarder.The simulation work is validated in this section using the MATLAB program.Additionally,steps show how the node acts as a confident forwarder and shares the channel in a compatible method to communicate,allowing for more packet bits to be transmitted by conveniently picking the channel between them.We cal-culate the confidence of the node at the start of the network by combining the reliability report for thefirst hop and the reliability report for the secondary hop.We then refer to the same node as the confident node in order to operate as a forwarder.As a result,we witness an increase in the leftover energy in the output.The percentage of data packets delivered has also increased.

Greedy Algorithm Applied to Relay Selection for Cooperative Communication Systems in Amplify-and-Forward Mode

Using a relaying system to provide spatial diversity and improve the system performance is a tendency in the wireless cooperative communications. Amplify-and-forward （AF） mode with a low complexity is easy to be implemented. Under the consideration of cooperative communication systems, the scenario includes one information source, M relay stations and N destinations. This work proposes a relay selection algorithm in the Raleigh fading channel. Based on the exhaustive search method, easily to realize, the optimal selection scheme can be found with a highly complicated calculation. In order to reduce the computational complexity, an approximate optimal solution with a greedy algorithm applied for the relay station selection is proposed. With different situations of the communication systems, the performance evaluation obtained by both the proposed algorithm and the exhaustive search algorithm are given for comparison. It shows the proposed algorithm could provide a solution approach to the optimal one.

Forward robust portfolio selection: The binomial case

We introduce a new approach for optimal portfolio choice under model ambiguity by incorporating predictable forward preferences in the framework of Angoshtari et al.[2].The investor reassesses and revises the model ambiguity set incrementally in time while,also,updating his risk preferences forward in time.This dynamic alignment of preferences and ambiguity updating results in time-consistent policies and provides a richer,more accurate learning setting.For each investment period,the investor solves a worst-case portfolio optimization over possible market models,which are represented via a Wasserstein neighborhood centered at a binomial distribution.Duality methods from Gao and Kleywegt[10];Blanchet and Murthy[8]are used to solve the optimization problem over a suitable set of measures,yielding an explicit optimal portfolio in the linear case.We analyze the case of linear and quadratic utilities,and provide numerical results.

Detection of Insider Selective Forwarding Attack Based on Monitor Node and Trust Mechanism in WSN

The security problems of wireless sensor networks (WSN) have attracted people’s wide attention. In this paper, after we have summarized the existing security problems and solutions in WSN, we find that the insider attack to WSN is hard to solve. Insider attack is different from outsider attack, because it can’t be solved by the traditional encryption and message authentication. Therefore, a reliable secure routing protocol should be proposed in order to defense the insider attack. In this paper, we focus on insider selective forwarding attack. The existing detection mechanisms, such as watchdog, multipath retreat, neighbor-based monitoring and so on, have both advantages and disadvantages. According to their characteristics, we proposed a secure routing protocol based on monitor node and trust mechanism. The reputation value is made up with packet forwarding rate and node’s residual energy. So this detection and routing mechanism is universal because it can take account of both the safety and lifetime of network. Finally, we use OPNET simulation to verify the performance of our algorithm.

Fast Variable Selection by Block Addition and Block Deletion

We propose the threshold updating method for terminating variable selection and two variable selection methods. In the threshold updating method, we update the threshold value when the approximation error smaller than the current threshold value is obtained. The first variable selection method is the combination of forward selection by block addi-tion and backward selection by block deletion. In this method, starting from the empty set of the input variables, we add several input variables at a time until the approximation error is below the threshold value. Then we search deletable variables by block deletion. The second method is the combination of the first method and variable selection by Linear Programming Support Vector Regressors (LPSVRs). By training an LPSVR with linear kernels, we evaluate the weights of the decision function and delete the input variables whose associated absolute weights are zero. Then we carry out block addition and block deletion. By computer experiments using benchmark data sets, we show that the proposed methods can perform faster variable selection than the method only using block deletion, and that by the threshold updating method, the approximation error is lower than that by the fixed threshold method. We also compare our method with an imbedded method, which determines the optimal variables during training, and show that our method gives comparable or better variable selection performance.

An Effective Control Report Based Security Countermeasure against the Joint Attacks of False Report Injection Attack and Selective Forwarding Attack

Sensor networks are vulnerable to many attacks because the sensor networks operate in open environments. It is easy to incur one or more attacks such as a selective forwarding attack, a false report injection attack. It is hard to defend the sensor network from the multiple attacks through existing security methods. Thus, we suggest an energy-efficient security method in order to detect the multiple attacks. This paper presents a security method to detect the false report injection attack and the selective forwarding attack in the sensor network using a new message type. The message type is a filtering message. The filtering message prevents from generating and forwarding false alert messages. We evaluated performance of our proposed method through a simulation in comparison with an application of SEF (statistical enroute filtering scheme) and CHEMAS (Check point-based Multi-hop Acknowledgement Scheme). The simulation results represent that the proposed method is 10% more energy-efficient than the application when the number of false reports is great while retaining the detection performance.

Performance analysis of selection cooperative networks over asymmetric fading channels

The performances of selection cooperation are investigated over asymmetric fading channels where the source-relay and the relay-destination channels experience Nakagami-m and Rayleigh fading,respectively.Decode-and-forward(DF)protocol is adopted and the Nth best relay is selected from M available relays.Probability density function(PDF)for the instantaneous signal-to-noise ratio(SNR)at the destination is derived first.Then,it is used to derive the exact expressions for outage probability and average symbol error rate(SER).The results hold for arbitrary M or N.Finally,simulations are carried out to verify the correctness of our theoretical analysis and results show that M and N almost have the same effect on the performance of outage probability and SER.

The Improvement of Relay Selection Schemes in Two-Hop Cellular Networks

In wireless networks, cooperative relaying could improve throughput by exploiting diversity. In order to reduce the amount of feedback for the channel gain, a semi-distributed scheme based on the relay feasible condition is proposed. Each relay node can measure its backward and forward channel gains. If both the channel gains are larger than a pre-defined threshold, this relay node is feasible. The final decision on the best relay selection is still given by the base station. Besides, the switch-and-examine relay selection scheme, which selects the first feasible relay node, is also investigated. Simulation results are presented to illustrate the advantage of two proposed schemes.

Relay Selection Strategy in the Secure Cooperative Communications System

With the low cost and low hardware complex considerations,cooperative systems are a tendency in the future communications.This work considers the secure cooperative communications systems.For a practical situation in the system,the scenario includes multiple source stations,multiple relay stations,multiple destination stations,and eavesdroppers.To analyze the optimal relay selection in the system,we begin with the performance analysis for a single source station and a single destination station.By applying two cooperative models,the amplify-andforward（AF） mode and decode-and-forward（DF）mode,the secrecy capacity is derived.Then,we apply the derived results to the considered environment to find the optimal relay assignment.By the way,the relay selection can be obtained by the exhaustive search algorithm.However,there are a lot of steps needed if the number of source stations is large.Hence,applying the characters of the cooperative modes in the relay selection,the pre-selection step is proposed with a mathematical derivation.It could be used for the practical situation without a long-time calculation.

A LOWER COMPLEXITY ANTENNA SELECTION FOR DF RELAY MIMO SYSTEMS

Based on the existing incremental selection algorithm for Decode-and-Forward (DF) Multiple Input Multiple Output (MIMO) systems, a faster one which combines the incremental selection with the decremental exclussion is proposed. Firstly, the algorithm selects one antenna which makes the increment of the capacity greatest in every step. Then, excludes the antennas whose contribution to the capacity is less than μ% of that of the best antenna. Simulations show that the proposed algorithm achieves comparable performance to the existing one and has obviously decreased complexity under the appropriate threshold μ% .

Performance of Nth Worst Full-Duplex Relay Selection over Nakagami-M Fading Channels

The performance analysis of Nth worst relay selection for the full-duplex (FD) mode over Nakagami-m fading channels is studied. We assume the relay employs the amplify-and-forward (AF) protocol. The closed-form expres-sions for the outage performance in terms of the received signal-to-noise ratio cumulative distribution function are derived. In the high signal-to-noise ratio regime, asymptotic outage probability is also investigated. Based on these expressions, the effect of several important network parameters, i.e., the number of relays and the order of selected relay, as well as the quality of the relay links, source-relay links, relay-destination links, are analytically characterized. Finally, numerical results are provided to verify and illustrate our mathematical analysis.

基于LightGBM-VIF-MIC-SFS的风电机组故障诊断输入特征选择方法

针对风电机组数据采集与监视控制(SCADA)系统数据维数较高、特征冗余、特征相关性高导致风电机组的故障诊断过程存在误差大、分类正确率低的问题,提出一种基于LightGBM-VIF-MIC-SFS的三段式特征选择方法。首先,根据LightGBM实现对所有特征的重要性计算,确定初步特征空间;其次,根据方差膨胀因子(VIF)和最大信息系数(MIC)构建相关性判别阵,据此评估一次筛选中重要性相近的特征,舍弃相似性高的输入特征;最后,使用序列前向搜索法对特征进行第3次处理,逐个输入前2次特征选择获得的特征,保留能提升系统性能的特征,从而实现最终特征的选取。在完成了模型的建立后,使用风电场真实SCADA系统数据进行性能评估,将所提方法与2种对比算法在6个数据集上进行对比,结果显示所提出的LightGBM-VIF-MIC-SFS相较2种对比特征选择算法有显著优势。对所提方法内部的3个模块进行了消融实验,有效验证了所提特征选取方法内部各个模块的有效性以及基于所提方法得到的最优特征空间的合理性及准确性。

基于模态阻尼指标的空间杆系结构作动器位置优化

针对空间杆系结构作动器的位置优化问题,本文基于线性二次型最优控制理论(LQR),建立了空间杆系结构振动的主动控制系统,提出了目标控制模态的模态阻尼最大化的作动器位置优化准则.采用四角锥网架结构和Levy型索穹顶结构来验证本文方法的有效性,并在控制效果和控制能量输入两方面与常用的模态控制力方法进行了对比分析.结果表明:随着作动器数量的增加,本文方法的控制效果和控制能量输入比模态控制力方法提升更快;在作动器数量相同或控制能量输入相同时,本文方法对外界激励的控制效果优于模态控制力方法.

基于发射天线选择的修改转发协作D2D网络的物理层安全

为了进一步提升与蜂窝网络共享频谱资源的解码转发(decode-and-forward,DF)协作终端直通(device-to-device,D2D)网络的物理层安全(physical layer security,PLS)性能,提出了一种D2D发送端采用发射天线选择(transmit antenna selection,TAS)的修改转发(modify-and-forward,MF)协作D2D-蜂窝网络PLS模型。配备多根发射天线的D2D发送端采用TAS技术,选择使D2D发送端至MF中继节点链路信干噪比最大的天线发送信号;中继采用MF协议将解码得到的合法信息进行修改后再转发,以避免被动窃听者能够解码出此阶段发送的合法信息,从而改善了D2D网络的PLS性能。推导了MF协作D2D网络的安全中断概率、非零安全容量概率和渐近安全中断概率的解析表达式,并与DF协作D2D网络的PLS性能进行对比分析。数值计算与仿真结果表明,MF协作D2D网络的PLS性能优于DF协作D2D网络,并且增大D2D发送端的发射天线数量,可以增强D2D网络的PLS性能。

中继选择NOMA无线系统的物理层安全

针对解码转发协作非正交多址接入(non-orthogonal multiple access,NOMA)系统物理层安全(physical layer security,PLS)性能较差,以及在多窃听者场景下PLS性能恶化的问题,提出了一种采用修改转发(modify-and-forward,MF)协议的多中继选择NOMA无线系统PLS模型。利用高斯-切比雪夫正交定理推导了非合谋或合谋窃听场景下多中继选择MF-NOMA无线系统的安全中断概率和渐近安全中断概率的近似表达式。仿真结果验证了多中继选择MF-NOMA无线系统PLS性能分析的准确性。结果同时也表明中继数目越多或窃听者数目越少,多中继选择MF-NOMA无线系统的PLS性能越好;合谋窃听比非合谋窃听更不利于多中继MF-NOMA无线系统的安全传输。

能耗均衡与节能的自适应水下路由协议

针对水下传感器网络中节点能耗不均衡和能量有限的问题,提出一种能耗均衡与节能的自适应水下路由协议ECBES(energy consumption balanced and energy saving adaptive underwater routing protocol)。构建双区非均匀分层拓扑。基于能耗均衡因子,利用拓扑和节点剩余能量计算节点转发优先级,实现自适应转发节点选择,均衡网络能耗。与此同时,通过候选转发区域各分区域中节点参与转发数据包的比例确定次优候选转发区域,将次优候选转发区域作为初始策略,利用策略迭代思想确定最优候选转发区域,保证投递率的同时减少不同网络规模中重复数据包的转发,降低网络的整体能耗。仿真结果表明,ECBES相比VBF、ES-VBF和ALRP,在不同节点数量下,节点死亡率均最低,在保证数据包投递率的同时,能耗最少。

一种5G网络协同通信自适应中继选择方案

针对协作通信网的中继选择问题,提出了一种基于贝叶斯推理的自适应中继选择方案。该方案拓展地运用了放大转发协议的原理,准确地分析了中继节点后验概率,并以此选取最优的中继节点进行信息传输。实验仿真结果表明,该方案在信噪比恒定的情况下,显著地提高了网络性能。

基于变换AUC的颈动脉斑块稳定性预测模型

为了准确识别颈动脉斑块的重要生物标志物,在改进生物标志物所包含信息量的度量方法的基础上,通过向前逐步回归建立了基于变换AUC(Transformed area under curve)的颈动脉斑块稳定性预测模型。首先,在ROC(Receiver operating characteristic)空间提出变换AUC,并给出该指标在双正态分布模型和自由分布模型下的估计方法;然后,使用R统计软件,对比分析变换AUC与AUC等常用评估指标对非传统生物标志物的评估性能;最后,基于浙江医院提供的影像数据,利用变换AUC度量生物标志物的信息量,使用向前逐步回归筛选模型的方法建立高精度的颈动脉斑块稳定性预测模型。研究结果表明,该颈动脉斑块稳定性预测模型的AUC值达到0.9以上,能够准确识别斑块的稳定性,为临床医师对患者进行个性化诊疗提供更精准的参考依据。

一种基于Select函数的嵌入式网络通信信息转发机制设计

为了解决在嵌入式网络多对多通信中出现网络拥塞造成网络性能指标下降、引起网络带宽资源浪费的问题,基于Select函数,提出一种单一进程的多目标睡眠等待的信息转发机制方法,当睡眠进程等待的几个目标通道中的任何一个有输入数据时,相应的设备驱动程序把睡眠中的进程唤醒。这样,既达到了进程与多个数据通道进行通信的目的,又避免使用报文队列增加资源消耗的弊端,使信息转发保持了较高的效率。该机制已经在Linux平台上实现并通过测试。