QoS Metrics Research Articles

On a Local Protocol for Concurrent File Transfers

We study a very natural local protocol for a file transfer problem. Consider a scenario where several files, which may have varied sizes and get created over a period of time, are to be transferred between pairs of hosts in a distributed environment. Our protocol assumes that while executing the file transfers, an individual host does not use any global knowledge; and simply subdivides its I/O resources equally among all the active file transfers at that host at any point in time. This protocol is motivated by its simplicity of use and its applications to scheduling map-reduce workloads. Here we study the problem of deciding the start times of individual file transfers to optimize QoS metrics like average completion time or MakeSpan. To begin with, we show that these problems are NP-hard. We next argue that the ability of scheduling multiple concurrent file transfers at a host makes our protocol stronger than previously studied protocols that schedule a sequence of matchings, in which no two active file transfers share a host at any time. We then generalize the approach of Queyranne and Sviridenko (J. Algorithms 45:202---212, 2002) and Gandhi et al. (ACM Trans. Algorithms 4(1), 2008) that relates the MakeSpan and completion time objectives and present constant factor approximation algorithms.

Speech Quality Evaluation Based Codec for VoIP Over 802.11P

Voice over Internet Protocol (VoIP) may provide good services through Vehicular ad hoc networks (VANETs) platform by providing services to many application scenarios range from safety to comfort. However, VANETs networks introduce many challenges for supporting voice with QoS requirements. In this paper, our study is based on Inter-Vehicle voice streaming rely on multi-hop fashion. For this task, a performance evaluation of various audio CODECs will be analyzed by mean of simulations. Furthermore, we test the impact of network environment on QoS metrics. To achieve good results, CODECs behaviour is tested by using mobility information obtained from vehicular traffic generator. The mobility model is based on the real road maps of an urban environment. Focusing on inter-vehicular voice traffic quality, we provide simulations results in terms of both user level (MOS) metrics and network level (such as Losses). According to this performance evaluation, we show that G.723.1 CODEC worked well in the urban VANET environment.

Finer Tuning Of QoS Mechanisms for Performance Enhancement of Wireless Networks

WLAN is supported by almost all of the modern communication devices. These devices are largely used for communication of multimedia data including real time data. There is limited QoS support in WLANs, which will become an impediment in deploying multimedia applications. The important QoS metrics for multimedia applications are delay, jitter, loss, and throughput. There are different mechanisms and techniques for controlling these metrics. A lot of work has been carried out as far as loss and throughput is concerned. This paper focuses mainly on reducing the delay and jitter. A study of the various QoS support mechanisms for wireless networks is carried out and suggestions for improvement have been proposed particularly pertaining to the MAC parameters which will lead to a more precise and finer tuning of the already available mechanisms.

FuzzyAcoRouter: An Efficient Network Packet Routing Algorithm Based on Mixing Fuzzy Control System and ACO

This study discusses new proposed Fuzzy AcoRouter. The aim of this study is to find optimal path for networks packet routing with satisfying QOS parameters. To make good decision, this method uses fuzzy control system and swarm intelligent tools. The result illustrates Fuzzy AcoRouter has more performance in QOS metrics in comparison with other standard routing protocols like OSPF. It will pave the way to apply intelligent method in next routing protocol generations.

A QoE-Aware Scheduler for HTTP Progressive Video in OFDMA Systems

HTTP progressive video downloading is becoming increasingly relevant in wireless and mobile networks. Therefore, improving the quality of experience (QoE) for this service is important for customer satisfaction. In this letter we propose a QoE-aware scheduling solution for the HTTP progressive video downloading in OFDMA systems. Whereas most scheduling strategies consider QoS metrics such as delay, jitter or throughput, our proposal takes into account a metric that directly affects the end-users experience. In particular, we propose to use an estimation of the amount of video data stored in the player buffer as the main criterion for resource assignment. The ultimate goal of using this criterion is the avoidance of playback interruptions. In particular, we have evaluated this scheduler in an LTE network simulator for the YouTube service, which is the most visited HTTP video streaming site. Our results show a significant improvement compared to the Multicarrier Proportional Fair scheduler, e.g. the number of videos with pauses decrease from 16.1% to 0% for 12 Mbps of cell offered load.

Measurement of QoS metric of multimedia traffic classes in wireless sensor networks

Measurement of QoS metric of multimedia traffic classes in wireless sensor networks

Energy Supported AODV (EN-AODV) for QoS Routing in MANET

A Mobile Ad-hoc Network (MANET) is a wireless network competent of autonomous actions. No infrastructure is required for nodes to communicate with each other in the network. MANET operates without centralized administration. The nodes are self configuring, independent, quickly deployable. Nodes are movable since topology is very vibrant and they have restricted energy and computing resources. Routing protocols should incorporate QoS metrics in route finding and maintenance, to support end-to-end QoS. General AODV routing faces problems like long route, time delay, mobility and many other while routing. The nodes low in energy level will not be in a position to complete the routing. The QoS parameters like throughput, PDR and delay are affected directly. The proposed Energy based AODV protocol (EN-AODV) announces energy and based on nodes sending and receiving rates and the sizes of the data to be transmitted it justifies whether its energy level is maintained or decreased. It calculates the energy levels of the nodes before they are selected for routing path. A threshold value is defined and nodes are considered for routing only if its energy level is above this threshold value. The work is implemented and simulated on NS-2. The simulation results have shown an increase in PDR, decrease in delay and throughput is maintained. The proposed EN-AODV provides more consistent and reliable data transfer compared to general AODV.

Study on QoS Routing Protocol for New Wireless Mesh Networks

A QoS aware routing protocol for Wireless Mesh Networks is studied in this paper, the QoS metrics taken into account are bandwidth in our studies, end to end delay and stability of the routes. The routing metric reflects the maximal available bandwidth of a routing path, which is calculated based on the available bandwidth of mesh nodes with the consideration of the interference caused by the hidden terminals in WMNs. With the help of admission control decision, QRBC uses the routing metric in the route discovery process to find a QoS guarantee route for the real-time applications. The simulation results demonstrate that the QRBC protocol can find a less interfering and bandwidth guaranteed routing path for real-time flows.

User QoS enhanced web service composition framework in cloud platforms

Recently, deploying web services in cloud platforms has become a popular issue that attracts plenty of attentions. Unlike typical service platforms, cloud system provides an elastic infrastructure for service provision and security isolation. As a result, the service composition in a cloud platform becomes more flexible and negotiable, especially when users have multiple QoS constraints with various weights. To address the problem of service composition with multiple QoS constraints in cloud systems, we propose a QoS-enhanced web service composition framework, in which evolution strategy is applied to solve the optimal service composition which is formulated as multiple choice multiple dimension knapsack problem. Based on the proposed service composition, a QoS negation mechanism is also designed with aiming to adapt the dynamical and elastic cloud environments. Extensive experiments are conducted to investigate the effectiveness of the proposed framework, and the results show that it can significantly reduce the costs of large-scale service-based application in terms of various QoS metrics.

QoS Aware Power Efficient Multicast Routing Protocol (QoS-PEMRP) with Varying Mobility Speed for Mobile Ad Hoc Networks

Power efficient multicast routing is one of the key issues in the field of mobile ad hoc networks. Multicasting is a term which refers to delivering data packets to a group of mobile nodes from an intended source. Quality of Service enlarges the support level of predictable performance for network systems. This research work focuses on design and development strategy of QoS aware power efficient multicast routing protocol which best suits for wireless nodes moving around the network with varying mobility speed. The QoS metrics such as average group delivery ratio, average power consumption and average delay are taken into account for measuring the performance of the proposed protocol QoSPEMRP. Extensive simulation results are carried out through NS2 simulator. From the simulation results it is shown that the proposed QoS-PEMRP outperforms On-Demand Multicast Routing Protocol (ODMRP) routing protocol by reduced delay and increased packet delivery ratio along with decreased power consumption.

Optimal rate and power allocation under quality‐of‐service requirements for wireless multihop networks

SUMMARYIn wireless networks, real‐time applications have strict QoS requirements for packet delay, packet loss, and reliability. However, most existing work has not considered these QoS metrics when allocating wireless resources so that the QoS requirements of real‐time applications may not be satisfied. To overcome this shortcoming, a rate and power allocation framework incorporating these QoS metrics is first proposed for slow‐fading systems. Second, two distributed algorithms are developed to solve this optimization framework although it is nonconvex and nonseparable. Third, an improved framework is proposed to deal with the rate and power allocation with QoS requirements for fast‐fading systems. It is shown that the fast‐fading state of the network does not need to be considered in this improved framework, and it can be solved using algorithms that are similar to those for the framework of slow‐fading systems. In the end, simulations show that our algorithms converge closely to the globally optimal solution. By comparison with an existing model, simulations also verify the validity of our frameworks on dealing with the rate and power allocation with QoS requirements. Copyright © 2012 John Wiley & Sons, Ltd.

A content-based publish/subscribe framework for large-scale content delivery

The publish/subscribe communication paradigm has become an important architectural style for designing distributed systems and has recently been considered one of the most promising future network architectures that solves many challenges of content delivery in the current Internet. This work is concerned with scaling decentralized content-based publish/subscribe (CBPS) networks for large-scale content distribution. A fundamental step for CBPS networks to reach the large-scale is to move from the current exhaustive filtering service model, where a subscription selects every relevant publication, to a service model capturing the quantitative and qualitative heterogeneity of information consumers requirements. Moreover, the proposed work aims at leveraging caching for increasing the communication efficiency of CBPS operating at large-scale characterized by widely spread information consumers with heterogeneous requirements, large number of publications and scarcity of end-to-end bandwidth. We propose and design a service model for addressing the consumers’ requirements for content-based information retrieval and describe the relevant protocols necessary to implement such a service. We evaluate the proposed approach, by using realistic workload scenarios and comparing different content and interest forwarding strategies as well as caching policies in terms of resource efficiency and user perceived QoS metrics.

Fuzzy Cost based Power Aware QoS Routing Protocol with Mobility Prediction in Mobile Ad Hoc Networks

Fuzzy Cost Based Power Aware QoS Routing (FCPAQR) protocol proposed to select an optimal path by considering multiple independent QoS metrics. Fuzzy inference rule which is used to calculate the QoS based fuzzy cost of each link to forward the data packets effectively and efficiently. Fuzzy cost is calculated based on various QoS Constraints. QoS constraints can be classified as Time Constraint (Delay and Jitter), Space Constraint (System Buffer), Frequency Constraint (System Bandwidth) Reliability Constraint (Error rate) [9]. Link Expiry Time(LET) and Energy Level are also additionally taken into account. Considering multiple QoS Constraints provide better result than taking single constraint into account. General Terms

QUALITY OF SERVICE AWARE REVERSE PATHAD-HOC ON-DEMAND DISTANCE VECTOR PROTOCOL

Mobile Ad-hoc Network (MANET) is aninfra structureless network that does not require any built-in infra structure and central control. Due to very fast mobility of nodes, there will be drastic changes in the network topology. So an adaptive routing protocol is needed for effective and reliable routing in MANET. Ad-hoc On-demand Distance Vector (AODV) routing protocol is the efficient and prominent routing protocol which may satisfy the above said issue. While making routing process in traditional AODV,onlyone route information will be sent as reply in the reverse path. This reply from the destination may be lost due to fast mobility of modes which in turn leads to the retransmission of route request packets to establish routes.The main cause of this problem is increased communication delay and reduction of several QoS metrics. The main goal of the new Novel QoS aware reliable routing algorithm is to send multiple route replies and establishes reliable data transmission between source and destination. The new NQARR-AODV protocol establishes paths on-request using a reliable reverse pathestablishment method. During pathestablishmentphase, the source node first sends the route requests through all available paths to the destination. The destination node,upon receiving the path requests,inturn rebroadcasts the reverse path requestsas like sender node has done. Upon receiving the multiple route replies from the destination, a path with high reliability is choosen by the source node using the three parameters, the MAC overhead, the Eminence of Link, node residual energy. NQARR-AODV path establishment method works well and requires only minimum steps. It also provides high energy efficiency and load balancing thus prolongs the network life time and makes up high reliability communications. The experimental values prove that the NQARR-AODV algorithmis more reliable and stable and outperforms AODV by reducing energy consumption, overhead and delay. Also NQARR-AODV gains bestratio of packets delivered than that of normal AODV. In our proposed NQARR-AODV protocol, the source node can find QoS aware reliable route to the destination.

Parallel Data Broadcasting for Optimal Client Service Ratio

This letter introduces service ratio-based optimization in multichannel data broadcast systems. The classic pursuit of data broadcast scheduling has revolved around QoS metrics, such as the minimization of the mean serving time or jitter. Recent studies in single channel systems have shown that this approach reduces the client service ratio, essentially forcing clients to abandon the system. Content discarding in single channel systems was then proven to maximize the service ratio. The present work introduces a novel algorithm for service-ratio-oriented assignment of data to multiple channels with different bandwidths. Comparison to related approaches demonstrates the superior scalability of the proposed algorithm.

클라우드 컴퓨팅에서 워크플로우의 특성을 고려한 스케줄링 기법

클라우드 컴퓨팅은 컴퓨팅 자원의 효율적 사용과 수월한 접근이라는 관점에서 사용자 및 서비스 제공자에게 모두 각광받고 있다. 한편, 클라우드 컴퓨팅의 자원은 이질적 환경으로 구성되는 경우가 많고 사용자의 워크플로우는 다양한 특성을 가진다. 따라서 본 연구의 목적은 이러한 환경에서 워크플로우의 응답성 요구에 따라 우선순위를 부여하고 워크플로우를 구성하는 태스크의 자원 할당시 응답성, 비용, 그리고 부하 균등으로 구성되는 QoS 메트릭을 구성하여 효율적으로 워크플로우를 스케줄링하는 것이다. 제안기법의 성능 평가를 위해 다양한 실험을 수행한 결과 응답성과 가용성이 향상되었음을 확인할 수 있었다. Cloud computing has got great popularity in recent times because users can easily access its resources as well as service providers can use efficiently use its resources. By the way, cloud computing are composed of heterogeneous resources and workflows of user application have various characteristics. So, the main goal of this paper is to design new efficient workflow scheduling algorithm, which classifies workflows through their importance degree and allocates resources to each workflow based on QoS metrics such as responsibility, cost and load balancing. Simulation results show that the proposed scheme can improve the responsibility as well as availability of resource.

Enhancing the Quality of Service in MANETs by Improving the Routing Techniques

The aim of this work is to modify the existing MANET reactive Multipath routing protocol Ad hoc On-demand Distance Vector (AOMDV). Since the Route discovery and route maintenance of AOMDV Routing 25 | P a g e protocol lead to a high number of unsuccessful packet deliveries from the source nodes to the destination nodes during broadcasting, it results in reducing the quality of service support for Mobile Ad Hoc Networks. This paper is about the systematic performance study made of existing routing protocol for Ad Hoc networks AOMDV based on QoS parameters delay and packet delivery ratio. Further, a novel Multipath QoS Aware Routing Protocol (MQARP) based on AOMDV is proposed to support delay, jitter and throughput constraints. Simulation using various traffic sources and movement patterns is made and existing version of the protocol is modified. The QoS metrics are measured by varying the pause time, speed and number of nodes. The performance of AOMDV and MQARP are compared using the network simulator. The simulator NS2.34 is used to simulate the performance of the metrics.

DSASync: Managing End-to-End Connections in Dynamic Spectrum Access Wireless LANs

Wireless LANs (WLANs) have been widely deployed as edge access networks that provide the important service of Internet access to wireless devices. Therefore, performance of end-to-end connections to/from such WLANs is of great importance. The advent of Dynamic Spectrum Access (DSA) technology is expected to play a key role in improving wireless communication. With DSA capability, WLANs opportunistically access licensed channels in order to improve spectrum-usage efficiency and provide better network performance. In this paper, we identify the key issues that impact end-to-end connection performance when a DSA-enabled WLAN is integrated with the wired cloud. We propose a new network management framework, called DSASync, to mitigate the identified performance issues. DSASync achieves this objective by managing the connections at the transport layer as a third-party supervisor and targets both TCP streams and UDP flows. DSASync requires no modifications to the network infrastructure or the existing network stack and protocols while ensuring transport protocol (TCP or UDP) semantics to be obeyed. It mainly consists of a combination of buffering and traffic-shaping algorithms to minimize the adverse side-effects of DSA on active connections. DSASync is evaluated using a prototype implementation and deployment in a testbed. The results show significant improvement in end-to-end connection performance, with substantial gains on QoS metrics like goodput, delay, and jitter. Thus, DSASync is a promising step toward applying DSA technology in consumer WLANs.

Generalized Multi-Constrained Path (G_MCP) QoS Routing Algorithm for Mobile Ad hoc Networks

In mobile ad hoc network, efficient routing protocol is required to perform route discovery and maintenance. These protocols can be classified into two main types which are proactive and reactive routing protocols. Most of them usually use the suboptimal path to reach destination without considering QoS parameters. This results in network congestion during high traffic load situation. Hence, many algorithms have been proposed to offer QoS routing to these protocols. However, most of them find the feasible path by using only one or two QoS metrics. This is not enough to support many applications with QoS guaranteed, especially multimedia applications since they have more stringent various QoS requirements. To provide QoS routing in ad hoc network based on such environment, we propose the effective algorithm called Generalized MCP (G_MCP) to find the feasible path based on proposed weighted Connectivity Index (combination of link connectivity and capacity) and non-linear cost (combination of multiple additive QoS metrics using non-linear function). We adopt the fall-back approach. That is, G_MCP will find the path from source to destination by considering weighted Connectivity Index first. If there is a tie, the path with least non-linear cost will be chosen. Based on this approach, G_MCP has the comparable time complexity with the Shortest-Widest Path algorithm. We construct the simulation in a number of scenarios based on proactive protocol called OLSR. According to the simulation results, it is obvious that G_MCP performances are superior than OLSR and Shortest-Widest Path algorithms in terms of throughput, packet delivery ratio, delay and success ratio. Therefore, it can be concluded that G_MCP is able to support various applications and be operated well in highly dynamic mobility environment

A Compendium on Service Oriented Architecture and Service Level Agreements

ABSTRACT Service Oriented Architecture provides an effective application integration and on-demand services provision. It supports loose coupling structure of the services which provides effective service management and also effective usage of the existing services. SOA gives strong support to business Innovation if implemented properly with proper understanding of the Principles of SOA. In order to incorporate the effective SOA, there should be a thorough deployment of the SOA, the SLA metrics needs to be standardized and focused. Since, the reliability of any service depends on the successful functionality. This article studies and reviews on a broad spectrum the Service Oriented Architecture and its Service Level Agreement (SLA) and its basic metrics. Keywords SOA, SLAs of SOA, Metrics of SLA in SOA, SLA Mon Tools 1. INTRODUCTION The SOA is an application architectural concept that defines the use of services to support business requirements. In SOA, the resources are made available as independent services, which can be accessed in a standardized manner. The Services are loosely coupled in order to facilitate the usage of the existing services and the components are reusable. In SOA environment, the Service Level Agreement (SLA) refers to mutually agreed understandings and expectation focused as the evaluation criteria for Quality of Service, between the Service Provider and Service Consumers. As the Services become more flexible, the Quality of Services becomes more critical and important. Every user is concerned about the Quality of Service. Thus there is a huge necessity of defining the QoS Metrics during the contract between the Service Providers and the Service Consumers, which would prove useful in making the Service transaction execute smoothly and efficiently [1]. More and more Services are done in order to create larger business process and services with the SOA developments [2], [3]. This initiates a closer examination of the quality of the services. The traditional mechanism makes it difficult to adapt to the complexity in open networked environment. The SLA is the contractual basis between the customer and the Service Provider about the Product. The Service of SOA is managed by SLA hence the Service Management can be achieved by the effective SLA management. In a Complex network environment requirements of end-to-end Quality of Service are different. The use of SLA guarantees in product can make the network more customer-focused. Further SLA based services are becoming a requirement to the provisioning of IP based network services to ensure Quality of Service. The Technical component of SLA is made up of a number of negotiated Service Level Objectives (SLO) which is based on Key Performance Indicators (KPI) metrics and Key Quality Indicators (KQI).