Quality of Service and Security on Cisco Network Devices, Coupled with the Development of a Mobile Application Prototype Software for Server Room Temperature Monitoring

In an era where digital technology is paramount, higher education institutions like the University of Zambia (UNZA) are employing advanced computer networks to enhance their operational capacity and offer cutting-edge services to their academic fraternity. Spanning across the Great East Road campus, UNZA has established one of the most extensive computer networks in Zambia, serving a burgeoning community of over 20,000 active users through a Metropolitan Area Network (MAN). However, as the digital landscape continues to evolve, it is besieged with burgeoning challenges that threaten the very fabric of network integrity—cyber security threats and the imperatives of maintaining high Quality of Service (QoS). In an effort to mitigate these threats and ensure network efficiency, the development of a mobile application to monitor temperatures in the server room was imperative. According to L. Wei, X. Zeng, and T. Shen, the use of wireless sensory networks to monitor the temperature of train switchgear contact points represents a cost-effective solution. The system is based on wireless communication technology and is detailed in their paper, “A wireless solution for train switchgear contact temperature monitoring and alarming system based on wireless communication technology”, published in the International Journal of Communications, Network and System Sciences, vol. 8, no. 4, pp. 79-87, 2015 [1]. Therefore, in this study, a mobile application technology was explored for monitoring of temperatures in the server room in order to aid Cisco device performance. Additionally, this paper also explores the hardening of Cisco device security and QoS which are the cornerstones of this study.

Optimizing QoS performance of service requests in grid

Workload of each service class varies dynamically in the grid environment, making the static service pool size allocation scheme unable to guarantee the QoS requirement of each service class. In this paper, we link the issue of dynamical service pool size allocation scheme with QoS requirement under the varying workload, and formulate the QoS performance of service requests in the grid environment by queue theory. Combined Lagrangian optimization with a bisearch approach, the problem of optimally allocating service pool size scheme is resolved. Simulation results show efficiency of the optimal service pool size allocation scheme.

Modeling and performance evaluation of QoS-aware job scheduling of computational grids

To achieve high quality of service （QoS） on computational grids, the QoS-aware job scheduling is investigated for a hierarchical decentralized grid architecture that consists of multilevel schedulers. An integrated QoS-aware job dispatching policy is proposed, which correlates priorities of incoming jobs used for job selecting at the local scheduler of the grid node with the job dispatching policies at the global scheduler for computational grids. The stochastic high-level Petri net （SHLPN） model of a two-level hierarchy computational grid architecture is presented, and a model refinement is made to reduce the complexity of the model solution. A performance analysis technique based on the SHLPN is proposed to investigate the QoS-aware job scheduling policy. Numerical results show that the QoS-aware job dispatching policy outperforms the QoS-unaware job dispatching policy in balancing the high-priority jobs, and thus enables priority-based QoS.

Toward Cloud Computing QoS Architecture:Analysis of Cloud Systems and Cloud Services

Cloud can be defined as a new computing paradigm that provides scalable, on-demand, and virtualized resources for users. In this style of computing, users can access a shared pool of computing resources which are provisioned with minimal management efforts of users. Yet there are some obstacles and concerns about the use of clouds. Guaranteeing quality of service QoS by service providers can be regarded as one of the main concerns for companies tending to use it. Service provisioning in clouds is based on service level agreements representing a contract negotiated between users and providers. According to this contract, if a provider cannot satisfy its agreed application requirements, it should pay penalties as compensation. In this paper, we intend to carry out a comprehensive survey on the models proposed in literature with respect to the implementation principles to address the QoS guarantee issue. © 2014 Chinese Association of Automation.

A DELAY BASED BACKOFF SCHEME FOR WLAN WITH QoS GUARANTEE AND ITS PERFORMANCE

Based on the Distributed Coordination Function (DCF) and the Enhanced DCF (EDCF) mechanisms in IEEE 802.11 and 802.11e, a novel backoff scheme for Wireless Local Area Network (WLAN) is proposed. The scheme is to solve the problem of the packet loss and the decrease of performance due to the increasing Contention Window (CW) when there are continuous collisions. In the proposed scheme, the CW of the packet will change dynamically with different delay for the different traffics. Mathematic formulas are presented to indicate the relationship between the CW and the delay character. ,The performance of the new scheme is also discussed with simulation results. The results show that it helps WLAN system handle multimedia simultaneously.

Network Coding and Quality of Service for Mobile <i>Ad Hoc</i>Networks

Network Coding is a relatively new forwarding paradigm where intermediate nodes perform a store, code, and forward operation on incoming packets. Traditional forwarding approaches, which employed a store and forward operation, have not been able to approach the limit of the max-flow min-cut throughput wherein sources transmitting information over bottleneck links have to compete for access to these links. With Network Coding, multiple sources are now able to transmit packets over bottleneck links simultaneously, achieving the max-flow min-cut through-put and increasing network capacity. While the majority of the contemporary literature has focused on the performance of Network Coding from a capacity perspective, the aim of this research has taken a new direction focusing on two Quality of Service metrics, e.g., Packet Delivery Ratio (PDR) and Latency, in conjunction with Network Coding protocols in Mobile Ad Hoc Networks (MANETs). Simulations are performed on static and mobile environments to determine a Quality of Service baseline comparison between Network Coding protocols and traditional ad hoc routing protocols. The results show that the Random Linear Network Coding protocol has the lowest Latency and Dynamic Source Routing protocol has the highest PDR in the static scenarios, and show that the Random Linear Network Coding protocol has the best cumulative performance for both PDR and Latency in the mobile scenarios.

Scheduling Algorithm with Quality of Service Support in IEEE 802.16 Networks

The MAC layer in IEEE802.16 is designed to differentiate service among traffic categories with different multimedia requirements.In this paper,a scheduling algorithm at MAC layer for multiple connections with diverse QoS requirements is proposed.As for this algorithm,each connection is assigned a priority,which is updated dynamically based on its service status concluding queue characteristic and channel state.A connection with the highest priority is scheduled each time.Analytical model is developed by assuming a Finite State Markov Chain(FSMC)channel model.Simulation results show that the proposed scheduling algorithm can improve the performance of mean waiting time and throughput in broadband wireless networks.

一种可扩展的Web Service QoS管理框架

Web Service是目前研究界和产业界广泛关注的技术之一.随着Web Service的广泛应用,研究者们普遍认识到,服务的非功能属性,即服务质量(Quality of Service,QoS)是面向服务的应用能否成功的关键因素之一.因此,研究者们尝试从多个角度对QoS相关问题展开了研究.然而,现有工作普遍关注基于QoS的动态服务选择和组装等上层应用技术,而对于如何获取、存储、度量QoS等基础支持技术研究较少,而这些基础性工作对QoS相关的研究工作具有显著的重要性.此外,不同应用领域对Web Service QoS的需求不尽相同,因此,需要有一套灵活的机制支持在QoS模型定义、QoS度量方法、QoS信息采集等方面体现出的领域特性.针对这个问题,文中提出了一个可扩展的Web Service QoS信息管理框架,详细分析了该框架涉及到的重要方法与核心技术,并给出了该框架在北京大学软件构件库系统中的设计决策和方案.最后,介绍了文中框架在一个863计划项目中的应用实例,该实例展示了用户根据其应用的领域需求对本框架进行扩展并进行Web Service QoS管理的方法,从而验证了本管理框架的可扩展性及实用性.

Web services composition with QoS bound based on simulated annealing algorithm

In order to enable quality-aware web services selection in the process of service composition,this paper first describes the non-functional requirements of service consumers and the quality of elementary service or composite service as a quality vector,and then models the QoS（quality of service）-aware composition as a multiple criteria optimization problem in extending directed graph.A novel simulated annealing algorithm for QoS-aware web services composition is presented.A normalizing for composite service QoS values is made,and a secondary iterative optimization is used in the algorithm.Experimental results show that the simulated annealing algorithm can satisfy the multiple criteria and global QoS requirements of service consumers.The algorithm produces near optimum solution with much less computation cost.

基于时间序列分析的Web Service QoS预测方法

通过网络提供服务的Web Service的服务质量会随着网络环境、服务器负载等因素的变化而变化,如何更好地帮助用户选择在未来一段时间内符合服务质量需求的Web Service,是目前服务计算领域中需要解决的关键问题之一。针对上述问题,提出了一种基于时间序列分析的Web Service QoS预测方法,并实现了相应的Web Service QoS自动预测工具。该工具能够根据Web Service的历史QoS数据,有效地预测未来短期内的QoS信息。以17832个Web Service的历史数据为基础,设计了相关实验,并验证了方法的有效性。

具有时延QoS保证的OFDM中继系统子载波配对与功率分配算法

本文研究具有直接通信链路的OFDM解码转发(Decode-and-Forward,DF)中继系统的子载波配对与功率分配算法,目标是在满足业务时延QoS要求的前提下最大化系统容量.利用有效容量模型,首先把OFDM DF中继系统的子载波配对与功率分配问题形成为混合整数规划问题,然后把其转化为连续松弛凸规划问题,利用凸优化方法得到原问题的最优解,从而提出了一种联合最优的子载波配对与功率分配迭代算法.理论推导结果和仿真结果表明,最优子载波配对与功率分配不仅取决于子载波的信道增益,还取决于业务的时延QoS要求.与已有算法相比,本文算法获得的有效容量最大.

Resource allocation based on fairness and QoS provisioning for OFDMA-WLAN system

To satisfy different service requirements of multiple users in the orthogo nal frequency division multiple access wireless local area network OFDMA-WLAN system downlink transmission a resource allocation algorithm based on fairness and quality of service QoS provisioning is proposed. Different QoS requirements are converted into different rate requirements to calculate the QoSs atisfaction level.The optimization object is revised as a fairness-driven resource optimization function to provide fairness. The complex resource allocation problem is divided into channel allocation and power assignment sub-problems. The sub-problems are solved by the bipartite graph matching and water-filling based method.Compared with other algorithms the proposed algorithm sacrifices less data rate for higher fairnes and QoS satisfaction.The sim ulation results show that the proposed algorithm is capableo fp rovi ding QoS and fairness and performs better in a tradeoff among QoS fairness and data rate.

基于合作中继的OFDM蜂窝网络的QoS感知子载波分配算法

针对基于中继的OFDM蜂窝网络,提出了一种基于合作中继的QoS感知子载波分配算法,即C-QSA(cooperative QoS-ware subcarrier allocation)算法。C-QSA算法利用基站与中继节点之间的合作传输机制来保证QoS业务的速率要求,允许中继节点进行比特重分配,充分利用无线系统的时变及多用户分集特性,提高无线资源的利用效率。C-QSA算法将子载波分配问题抽象为非线性整数规划,以最大化系统效用为目标,同时满足QoS业务的速率要求。仿真结果表明,C-QSA算法在用户效用及吞吐量等性能方面都有明显优势,系统实际效用接近理论最优值。

QoS驱动的Web services动态计价机制研究

结合Web services的服务质量(QoS)因素和用户经验,对Web services的计价机制进行研究,提出一种QoS驱动的Web services动态计价模型,描述其计价过程,并给出相应的实现算法。通过对模型的简单实现,经测试这一计价模型在准确性和合理性上具有一定优势。

基于合作中继的OFDM蜂窝网络的QoS感知资源调度算法

针对基于中继的OFDM蜂窝网络,该文考虑具有不同QoS要求的混合业务场景,引入合作传输机制,提出了一种基于合作中继的QoS感知资源调度算法,解决了合作中继节点选取,子载波分配以及功率控制等问题。以最大化系统效用为目标,在考虑QoS业务的速率要求与基站功率约束的同时,针对中继结构引入了中继节点的功率约束。为降低计算复杂度,将原非线性组合优化问题分解为子载波分配与功率控制两个子问题。仿真结果表明,该文所提算法在能量节约、系统效用,吞吐量等性能方面都有显著优势。

OFDMA系统中基于QoS的资源分配算法

针对正交频分多址(OFDMA)系统多用户分集的特点,提出一种基于用户服务质量(QoS)的自适应资源分配算法。利用多用户分集增益和自适应调制编码对功率进行平均分配,从而降低算法的复杂度。仿真结果表明,该算法虽然使系统吞吐量略有减小,但在用户QoS保证与用户公平性方面均有较大的性能提升。

基于QoS驱动的OFDMA中继系统节能资源分配算法研究

文章研究基于QoS驱动的OFDMA放大转发中继系统节能资源分配算法,目标是在满足各用户业务时延QoS要求的前提下,最小化OFDMA中继系统总功率.基于有效容量模型,首先把OFDMA放大转发中继系统资源分配问题形成为混合整数规划问题,然后通过整数约束连续松弛化,把问题转化为凸优化问题.通过求解该凸问题,推导得到了资源分配的迭代优化算法.仿真结果表明,与已有算法相比,对于各种类型时延QoS要求的无线业务,文章提出的资源分配优化算法均可明显降低系统消耗功率.

QoS区分的高速移动OFDMA系统无线资源分配

针对高速移动环境下多业务多用户正交频分多址(OFDMA)系统下行链路提出一种动态资源分配方案。针对具有不同时延要求的多种类型数据包的数据流,提出了一种考虑多种时延服务质量(QoS)要求的动态资源分配算法。通过应用排队论原理,将用户的时延要求转化为速率约束,结合多普勒频移产生的中断概率的约束,形成一个高速移动环境下考虑用户不同QoS要求的最优化问题。该优化问题为混合整数非线性规划,直接求解的复杂度非常高。为了解决原问题,提出了次优方法。仿真结果表明,在高速移动环境下,提出的方法在保障用户各种QoS时延要求的同时,有效地提高了系统的容量。

基于QoS的认知OFDM无线电系统自适应资源分配

根据认知无线电的特点和正交频分复用的传输特性,提出了一种针对认知OFDM无线电系统的自适应资源分配算法.该算法在子载波和功率分配中,通过把次用户对主用户干扰的功率限制在主用户可容忍的门限以下,使次用户信道容量最大化.同时,利用比例公平性保证了每个用户的通信服务质量.仿真结果验证了所提算法的性能和有效性.