基于Fat-tree的高性能互联网络性能优化与分析

高性能互联网络对于高性能计算机的性能具有重要的影响,而高性能网络中各个模块的设计都会影响到网络的最终性能,因而前期的网络仿真显得尤为重要.HPCSim是基于OMNeT++平台自主开发的高性能网络仿真器,包括了网络拓扑和仿真参数自动生成工具PySim以及仿真结果分析和可视化工具PyVisual.仿真器中对全缓存高阶路由器结构进行了改进,提出了一种5级流水线的高阶路由器,能够减少路由信息缓存开销同时将网络吞吐率从基准路由器下的0.75提升至0.95.此外,还对硅光互联链路进行了逻辑抽象,并在Fat-tree拓扑上对链路性能和网络吞吐率的关系进行了分析.

构建高性能物联网平台消息引擎的用户友好系统应用

物联网技术的快速发展使大量的传感器和设备能够互联并产生海量的数据。为了高效地管理和处理这些数据,构建一款高性能的消息引擎至关重要。介绍一款高性能消息引擎的核心功能,包括数据接收模块、一级队列模块和处理模块,以及其在用户友好系统应用中的优势和实际应用场景。同时,还讨论了技术的可扩展性和适应性,以及在设计用户界面时的关键因素。高性能消息引擎的应用有望提高数据处理效率、数据验证的准确性和系统的稳定性,从而满足不同领域的需求。

对战术互联网现存不足及攻击手段初探

战术互联网技术是未来信息战争的主要支撑技术。本文基于战术互联网研究现状,详细讨论了战术互联网在技术应用、战术安全方面存在的不足以及缺陷。

一种高效通用的TCP尾部丢包恢复算法

随者互联网时代的到来,如何提升互联网应用的交互性能逐渐成为时下的研究热点;而在当今的互联网环境中,网络带宽已经不是瓶颈,网络时延成为影响应用交互性能的关键因素.作为互联网时代的主要应用,Web应用的网络时延受到TCP尾部丢包现象的严重影响.Tail Loss Probe算法是一种通过发送探针包来触发恢复的高效易部署的TCP尾部丢包恢复算法,但其需要修改现有的TCP加速机制,存在影响互联网稳定性的风险.针对Tail Loss Probe算法存在的不足,提出一种Double Tail Loss Probe算法,该算法对不同的尾部丢包模式进行细化处理且在适当时机下发送两个探针包以加速恢复并实现与现有TCP机制的友好兼容,从而保证互联网数据流通的稳定性.实验表明,在不同的丢包粒度和传播时延下,Double Tail Loss Probe算法都展现出更快的恢复速度;尤其在丢包粒度较大时,相比Tail Loss Probe,该算法取得了约20%的性能提升.

Toward Energy-Efficiency Optimization of Pktgen-DPDK for Green Network Testbeds

The packet generator （pktgen） is a fundamental module of the majority of soft- ware testers used to benchmark network pro- tocols and functions. The high performance of the pktgen is an important feature of Future Internet Testbeds, and DPDK is a network packet accelerated platform, so we can use DPDK to improve performance. Meanwhile, green computing is advocated for in the fu- ture of the internet. Most existing efforts have contributed to improving either performance or accuracy. We, however, shifted the focus to energy-efficiency. We find that high per- formance comes at the cost of high energy consumption. Therefore, we started from a widely used high performance schema, deeply studying the multi-core platform, especially in terms of parallelism, core allocation, and fre- quency controlling. On this basis, we proposed an AFfinity-oriented Fine-grained CONtrolling （AFFCON） mechanism in order to improve energy efficiency with desirable performance. As clearly demonstrated through a series of evaluative experiments, our proposal can reduce CPU power consumption by up to 11% while maintaining throughput at the line rate.

Impacts of feedback delay and estimation error on secrecy performance of MISO single eavesdropper cognitive radio networks

Due to the broadcast nature of wireless transmission medium,security threats may hinder propagation of cognitive radio systems for commercial and military data application. This paper sets a channel error analytical framework and studies the joint impact of estimation errors and feedback delay on secrecy performance in cognitive radio networks. Under the assumption that system applies beamforming and jamming scheme,a multi-antenna cognitive base station( CBS) sends confidential signals to a secondary user( SU) in the presence of M primary users( PUs) and an eavesdropper. Assuming only imperfect channel state information( CSI) about the receivers is available,secrecy rate,outage probability,secrecy throughput are deduced to obtain a closed-form expression. It is shown that while the transmit power increases,secrecy throughput would reach to a constant. Simulation results show that feedback delay adversely impacts on secrecy rate,connection outage probability and secrecy throughput,while estimation error causes more impact on secrecy outage probability. Furthermore,the secrecy rate could increase progressively with the transmit power only if there exists no feedback delay.

Error Outage Probabilities of Dual-Hop Relay Channels in a Poisson Interference Field

In the promising cooperative communication systems,network performance is mainly affected by interference instead of noise.In this paper,we consider the performance degraded by the Poisson filed interference in the dual-hop relay channels.We focus on the discussions of error outage probability (EOP) performance with a selective-decode-and-forward (SDF),amplify-and-forward (AF),or fixed-decode-and-forward (DF) cooperation protocol.Finally,the simulation results present the performance with different cooperation protocols with interference in a Poisson field.

Application Scenarios and Enabling Technologies of 5G

Fast growth of mobile internet and internet-of-things has propelled the concept formation and research on 5G wireless communications systems which are to be standardized around 2020(IMT-2020).There will be diverse application scenarios expected for 5G networks.Hence,key performance indicators(KPIs) of 5G systems would be very diverse,not just the peak data rate and average/edge spectral efficiency requirements as in previous generations.For each typical scenario,multiple technologies may be used independently or jointly to improve the transmission efficiency,to lower the cost,and to increase the number of connections,etc.Key enabling technologies are discussed which include massive MIMO,ultradense deployment specific techniques,nonorthogonal transmission,high frequency communications,etc.

Analysis on Conditions of Northwest,North China and Shandong Power Grids Interconnection

This paper analyzes the possibility and benefits of interconnection of Northwest Power Grid with North China and Shangdong power grids. With different energy resources and power demand patterns, these three power grids have large potential benefits in future interconnection.

Attack Resistant Trust Management Model Based on Beta Function for Distributed Routing in Internet of Things

With the rapid development of Internet of Things (IoT),the issue of trust in distributed routing systems has attracted more research attention.The existing trust management frameworks,however,suffer from some possible attacks in hostile environments,such as false accusation,collusion,on-off,and conflicting behavior.Therefore,more comprehensive models should be proposed to predict the trust level of nodes on potential routes more precisely,and to defeat several kinds of possible attacks.This paper makes an attempt to design an attack-resistant trust management model based on beta function for distributed routing strategy in IoT.Our model can evaluate and propagate reputation in distributed routing systems.We first describe possible attacks on existing systems.Our model is then proposed to establish reliable trust relations between self-organized nodes and defeat possible attacks in distributed routing systems.We also propose a theoretical basis and skeleton of our model.Finally,some performance evaluations and security analyses are provided to show the effectiveness and robustness of our model compared with the existing systems.

Function chain neural network prediction on heat transfer performance of oscillating heat pipe based on grey relational analysis

As for the factors affecting the heat transfer performance of complex and nonlinear oscillating heat pipe (OHP),grey relational analysis (GRA) was used to deal with the relationship between heat transfer rate of a looped copper-water OHP and charging ratio,inner diameter,inclination angel,heat input,number of turns,and the main influencing factors were defined.Then,forecasting model was obtained by using main influencing factors (such as charging ratio,interior diameter,and inclination angel) as the inputs of function chain neural network.The results show that the relative average error between the predicted and actual value is 4%,which illustrates that the function chain neural network can be applied to predict the performance of OHP accurately.

Mobile Internet Applications：Impact on Future Wireless Communications System

Based on the analysis of application status in real network,the trace model of some typical mobile Internet applications data is given and their impact on 2G/3G network is discussed in this paper.Furthermore,in order to support the mobile Internet application efficiently in future,the issues including the impact on the Long Term Evolution (LTE-A) system and some potential solutions for performance optimization are studied.Based on the trace data model of IM traffic,the performacne evaluaiton of LTE-A system shows that some specific configuration machanisms can play an important role in improving network system efficiency in the case of IM traffic.