Proper Quality Of Service Research Articles

PERFORMANCE ANALYSIS OF DUAL-PARALLEL/DUAL-ELECTRODE MACH-ZEHENDER MODULATOR-BASED RADIO-OVER-FIBER SYSTEM AGAINST THIRD-ORDER INTERMODULATION ERRORS

The rapid development in wireless networks required by mobile and broadband users in terms of capacity, data rate, bandwidth, cost effectivity, green communications, proper quality of service, and so on create the need of a robust system against nonlinear errors. In view of this, the performance of a dual-parallel/dual-electrode Mach-Zehender modulator-based targeted radio-over-fiber (RoF) system for multitone transmission against severe nonlinear errors (i.e., third-order intermodulation) is analyzed. Two-tone radio frequency signals, operating at 9 GHz and 8 GHz, are used in the proposed system. The analytical analysis is confirmed and validated by simulation results using OptSim software. Further, comparative findings are found by considering a conventional Mach-Zehender modulator-based RoF system. The reduction in the third-order intermodulation errors of 21 dB over a fiber distance of 10 km by the proposed method over a conventional system and the obtained results find the implementation of the proposed method to be a robust wireless network.

Energy and quality of service-aware virtual machine consolidation in a cloud data center

The large-scale virtualized Cloud data centers consume huge amount of electrical energy leading to high operational costs and emission of greenhouse gases. Virtual machine (VM) consolidation has been found to be a promising approach to improve resource utilization and reduce energy consumption of the data center. However, aggressive consolidation of VMs tends to increase the number of VM migrations and leads to over-utilization of hosts. This in turn affects the quality of service (QoS) of the applications running in the VMs. Thus, reduction in energy consumption and at the same time ensuring proper QoS to the Cloud users are one of the major challenges among the researchers. In this paper, we have proposed an energy efficient and QoS-aware VM consolidation technique in order to address this problem. We have used Markov chain-based prediction approach to identify the over-utilized and under-utilized hosts in the data center. We have also proposed an efficient VM selection and placement policy based on linear weighted sum approach to migrate the VMs from over-utilized and under-utilized hosts considering both energy and QoS. Extensive simulations using real-world traces and comparison with state-of-art strategies show that our VM consolidation approach substantially reduces energy consumption within a data center while delivering suitable QoS.

Intelligent Municipal Heritage Management Service in a Smart City: Telecommunication Traffic Characterization and Quality of Service

The monitoring of cultural heritage is becoming common in cities to provide heritage preservation and prevent vandalism. Using sensors and video cameras for this task implies the need to transmit information. In this paper, the teletraffic that cameras and sensors generate is characterized and the transmissions’ influence on the municipal communications network is evaluated. Then, we propose models for telecommunication traffic sources in an intelligent municipal heritage management service inside a smart sustainable city. The sources were simulated in a smart city scenario to find the proper quality of service (QoS) parameters for the communication network, using Valencia City as background. Specific sensors for intelligent municipal heritage management were selected and four telecommunication traffic sources were modelled according to real-life requirements and sensors datasheet. Different simulations were performed to find the proper CIR (Committed Information Rate) and PIR (Peak Information Rate) values and to study the effects of limited bandwidth networks. Packet loss, throughput, delay, and jitter were used to evaluate the network’s performance. Consequently, the result was the selection of the minimum values for PIR and CIR that ensured QoS and thus optimized the traffic telecommunication costs associated with an intelligent municipal heritage management service.

Semi-Random Access in Small Cells With User Priority

In a small cell system, centralized control can be a problem for the visiting users (VUs) who randomly enter and leave with high mobility. In this letter, we propose a semi-random access scheme to achieve the coexistence of users with different control modes: centralized control for local users (LUs) and decentralized control for VUs. We adopt randomized power control and successive interference cancellation techniques to optimize the system within a quality of service (QoS) constraint of LUs. Simulation results show that most VU throughput gain can be achieved at the cost of marginal LUs’ outage performance loss. The two types of users can well coexist under a proper QoS constraint, bringing about increased total throughput.

The Impact of Traffic Management Tools Application on the Business Computer Network Performance

This paper presents a case study of the Quality of Service (QoS) application in a business network with Triple play services – voice, video, data. An experiment is performed on real network laboratory devices, and compares two situations – the impact of congested network on the services in the situation without QoS being deployed, and the situation with proper QoS applied. Results are evaluated with both the objective (delay, jitter, packet loss) and subjective metrics (audible and visual assessment), and clearly prove the usefulness of the QoS application which can be critical in businesses relying on a stable and guaranteed network connection.

Improving QoS and security in wireless ad hoc networks by mitigating the impact of selfish behaviors: a game‐theoretic approach

ABSTRACTSelfish users are known to be a severe security threat for wireless ad hoc networks. In particular, they can exploit mechanisms designed to assure quality of service (QoS) in the network. In this paper, the problem of backoff misbehavior in IEEE 802.11 enhanced distributed channel access (EDCA) networks is studied using a game‐theoretic approach. First, it is shown how this selfish behavior can disrupt traffic differentiation. Then, a solution is proposed, which encourages standard‐compliant behavior and thus proper QoS provisioning. This solution is based on punishing selfish nodes by degrading their throughput proportionally to the degree of misbehavior. A practical application of the solution is proposed, which is verified through simulations. Results show that the suggested mechanism considerably improves QoS provisioning in IEEE 802.11 EDCA ad hoc networks in the presence of selfish nodes. Furthermore, it is shown that the mechanism is adaptive, does not have a negative impact on the throughput of well‐behaving nodes, and provides legacy node support. Copyright © 2012 John Wiley & Sons, Ltd.

Distributed Contract Negotiation System for Virtual Organizations

Nowadays, with the broadening usage of distributed systems and Grid, the need for cooperation between many different heterogeneous organizations occurs. Such cooperation usually requires sharing of access to data, service and other tangible or intangible resources. To accomplish such cooperative efforts between organizations, an idea of the Virtual Organization (VO) emerged. It allows the organizations to share resources between the partners, while enforcing proper quality of service and security. In order to enable creation of such Virtual Organization, it is necessary to allow the participants of the VO to negotiation an agreement concerning the rules of cooperation, which will be encoded in a machine processable format. In this paper we present the application of the ESB integration architecture in the specialized distributed contract negotiation service - the FiVO DCNS, which is responsible for distributing contract negotiation events and queries between components of FiVO deployed in different organizations.

Design and Analysis of a Network-Assisted Fast Handover Scheme for IEEE 802.16e Networks

The IEEE 802.16e standard provides quality of service (QoS) for real-time traffic; however, packet transmission disrupted by the handover (HO) process is still a big concern, particularly when frequent HO is performed by mobile stations (MSs) with high mobility. Therefore, an HO scheme that supports frequent HO and provides short service disruption time (SDT) is necessary for providing QoS to real-time traffic. In this paper, we present a novel network architecture, which complies with the IEEE 802.16e standard, to support seamless frequent HO, particularly for MSs with high mobility. Based on this architecture, a network-assisted fast HO (NFHO) scheme is proposed to shorten SDT during the HO process. By resolving connection identifier (CID) assignment and uplink (UL) timing adjustment issues, the proposed NFHO scheme can restart both the UL and downlink (DL) packet transmissions before the MS proceeds to the HO ranging, which is a unique feature of our scheme. In addition, based on the NFHO scheme, an analytic model has been developed to investigate the expected number of buffered packets, packet loss probability, and SDT during HO. Performance evaluation results show that the NFHO scheme reduces the DL SDT by 75%, compared with the IEEE 802.16e hard HO scheme, and it also reduces the UL SDT by 55.6% and 75% compared with the work of Jiao and the IEEE 802.16e hard HO scheme (also the work of Choi ), respectively. In addition, the proposed NFHO scheme has the best performance in terms of expected number of buffered packets and packet loss probability among existing hard HO schemes for the IEEE 802.16e. Furthermore, our analytic model can be integrated into an admission-control policy to guarantee proper QoS for ongoing HO MSs.

Increasing Throughput and QoS Using Bandwidth and Region Division with Frequency Overlay over Multicell Environments

A cell planning and resource allocation scheme called EBRD (Enhanced Bandwidth and Region Division) is presented for improving channel capacity and for maintaining a proper QoS (Quality of Service) over the downlink OFDMA (Orthogonal Frequency Division Multiple Access) system. Through an optimal combination of sectorization and frequency overlay, the EBRD scheme improves both channel capacity and outage probability. In order to analyze the performance of the proposed algorithm, the outage probability is obtained as a closed numerical form. In the simulation, the EBRD scheme outperforms 3-sectorization in terms of throughput and outage probability.

확장 가능한 영상 부호화에서 전 확장성을 고려한 품질 메트릭

다양한 멀티미디어 영상 서비스 환경에 최적의 서비스 품질(Quality of Service, QoS)을 제공하는 것은 중요 이슈 중 하나이다. 이를 위해서 다양한 서비스 환경에 따라 쉽게 확장 가능한 영상 부호화 기술과 영상의 품질을 계량적으로 표현하는 기술이 필요하다. 본 논문에서는 확장 가능한 영상 부호화(Scalable Video Coding, SVC)에 기반한 영상에 대해 영상의 내용 특징 정보와 전 확장성, 즉 시간적, 공간적, 품질적 확장을 고려한 새로운 품질 메트릭을 제안한다. 실험 결과, 제안된 품질 메트릭은 측정된 주관적 점수와의 상관계수(correlation coefficient)가 평균 0.9이상으로 우수한 성능을 증명하였다. 본 논문에서 제안한 메트릭은 영상의 다양한 프레임 율, 화질, 공간 해상도, 그리고 모션 특성과 같은 부호화 조건에 따른 품질측정이 가능하여 최적의 부호화 조건을 결정할 수 있다. Currently, the efficient adaptive video streaming services and coding techniques are required to ensure quality of service (QoS) in diverse multimedia environments. To maintain optimal video quality in these environments, it is required to support scalable video coding (SVC) technique and proper QoS metric methods. In this paper, we propose a new quality metric that takes in to the temporal, the SNR, the spatial scalability on SVC. Experimental results shows that proposed method has a higher correlation with the subjective quality. We expect that the proposed metric plays an important role in deciding the coding parameter to optimize the quality of the SVC based video.