Application-level Quality Of Service Research Articles

Analysis and adaptive optimization of vehicular safety message communications at intersections

Safety-related applications in Vehicular Ad-hoc Networks (VANETs) can help to reduce the number of traffic accidents by periodically broadcasting Basic Safety Messages (BSMs). But considering that the density and topology of VANET change frequently, the Quality of Service (QoS) of safety applications with the fixed transmission parameters would not always meet the requirements of safety-related applications. In this paper, we firstly propose an analytical model to evaluate the performance of the BSM broadcast in VANET at the intersections. The effect of the traffic light is also taken into account by introducing the non-homogeneous Poisson process (NHPP) vehicle distribution, which is simulated by microscopic traffic simulator SUMO and validated by Kolmogorov-Smirnov (K-S) test. Secondly, the number of vehicles in the hidden terminal area and the concurrent transmission area need to be computed by complex integral computations for the proposed analytical model for evaluating the QoS of the safety applications, while the vehicle BSMs provide the vehicle location, speed, and transmission parameters, and these BSMs could be measured and collected in a timely manner to integrate into the analytical model to save the complex integral calculations. Based on the cross-validation QoS metrics between the NS2 (Network Simulator-ns-2) simulation and the analytical model, we employ the vehicle entity of the NS2 simulation model to represent the actual vehicle BSMs, to obtain the number of vehicles in the hidden terminal area and the concurrent transmission area. Finally, to maximize the transmission capacity and minimize the delay under the constraint of maintaining a high application-level QoS of safety applications, a multi-objective optimization scheme with Bare Bones Particle Swarm Optimization (BBPSO) is proposed to dynamically adjust multi transmission parameters. The accuracy of the proposed analytical model is validated by the NS2 simulation. The experimental results also show that the optimized ones could get better results compared with the real test-bed used transmission parameters. Furthermore, the comparisons with slotted-p(or 1)-persistent protocol and CSMA/CA with retransmission strategy show that the proposed solution could make VANET work with better performance at various vehicle densities.

Adaptive optimization of QoS constraint transmission capacity of VANET

Safety applications would be one of the most important on-board implementations in Vehicular Ad-hoc Network (VANET). Broadcasting the Basic Safety Message (BSM) periodically could help drivers increase their awareness range for preventing casualties of traffic accidents or reducing the number of traffic accidents. Usually, the safety applications have more stringent performance requirements (e.g. time delay and reliability) than other kinds of applications. However, because the vehicle density and speed are both changed frequently, the optimal network transmission parameters should not remain the same. So, setting constant transmission parameters in all conditions may cause problems, such as channel congestion, packet collisions and so on, which could degrade Quality of Service (QoS) of safety applications. For the purpose of maximizing the transmission capacity and keeping the application-level QoS of safety applications meeting their requirements, this paper proposes an optimization scheme with standard Particle Swarm Optimization (PSO) to adjust transmission parameters dynamically. The experimental results show that the optimized transmission parameters can get better results on transmission capacity and awareness probability compared with the transmission parameters which are used in real testbeds.

An Application-Level QoS Control Method Based on Local Bandwidth Scheduling

Quality of service (QoS) is an important performance indicator for Web applications and bandwidth is a key factor affecting QoS. Current methods use network protocols or ports to schedule bandwidth, which require tedious manual configurations or modifications of the underlying network. Some applications use dynamic ports and the traditional port-based bandwidth control methods cannot deal with them. A new QoS control method based on local bandwidth scheduling is proposed, which can schedule bandwidth at application level in a user-transparent way and it does not require tedious manual configurations. Experimental results indicate that the new method can effectively improve the QoS for applications, and it can be easily integrated into current Web applications without the need to modify the underlying network.

Quality of service control in proactive wireless sensor networks via lifetime planning

Successful exploitation of wireless sensor networks (WSNs) depends intuitively on the enabling technologies as well as the provision of application-level quality of service (QoS). Current research mostly focuses on maximising the network lifetime without considering the predefined task time. In this paper, we firstly provide a survey of QoS control approaches for WSNs. Subsequently, we propose a novel QoS control method, referred to as lifetime planning. Based on the design-time knowledge, lifetime planning provides users/applications with best-effort QoS, while meeting the required time to complete the assigned task. To this end, an 'upper' and a 'lower' QoS boundary have to be defined for each metric at design-time. During run-time, a self-adaptation framework confines the metrics between these boundaries. We then consider an office monitoring scenario with a cluster-tree topology for performance evaluation. Simulation results in Contiki OS show that lifetime planning tremendously improves the performance while meeting the required lifetime.

Distributed in-network processing and resource optimization over mobile-health systems

Advances in wireless and mobile communication technologies has promoted the development of Mobile-health (m-health) systems to find new ways to acquire, process, transport, and secure the medical data. M-health systems provide the scalability needed to cope with the increasing number of elderly and chronic disease patients requiring constant monitoring. However, the design and operation of such systems with Body Area Sensor Networks (BASNs) is challenging in twofold. First, limited energy, computational and storage resources of the sensor nodes. Second, the need to guarantee application level Quality of Service (QoS). In this paper, we integrate wireless network components, and application-layer characteristics to provide sustainable, energy-efficient and high-quality services for m-health systems. In particular, we propose an Energy-Cost-Distortion solution, which exploits the benefits of in-network processing and medical data adaptation to optimize the transmission energy consumption and the cost of using network services. Moreover, we present a distributed cross-layer solution, which is suitable for heterogeneous wireless m-health systems with variable network size. Our scheme leverages Lagrangian duality theory to find efficient trade-off among energy consumption, network cost, and vital signs distortion, for delay sensitive transmission of medical data. Simulation results show that the proposed scheme achieves the optimal trade-off between energy efficiency and QoS requirements, while providing 15% savings in the objective function (i.e., energy-cost-distortion utility function), compared to solutions based on equal bandwidth allocation.

Research on resource allocation for multi-tier web applications in a virtualization environment

Resource allocation for multi-tier web applications in virtualization environments is one of the most important problems in autonomous computing. On one hand, the more resources that are provisioned to a multitier web application, the easier it is to meet service level objectives (SLO). On the other hand, the virtual machine which hosts the multi-tier web application needs to be consolidated as much as possible in order to maintain high resource utilization. This paper presents an adaptive resource controller which consists of a feedback utilization controller and an auto-regressive and moving average model (ARMA)-based model estimator. It can meet application-level quality of service (QoS) goals while achieving high resource utilization. To evaluate the proposed controllers, simulations are performed on a testbed simulating a virtual data center using Xen virtual machines. Experimental results indicate that the controllers can improve CPU utilization and make the best tradeoff between resource utilization and performance for multi-tier web applications.

On assuring end-to-end QoE in next generation networks: challenges and a possible solution

In next generation networks, voice, data, and multimedia services will be converged onto a single network platform with increasing complexity and heterogeneity of underlying wireless and optical networking systems. These services should be delivered in the most cost- and resource-efficient manner with ensured user satisfaction. To this end, service providers are now switching the focus from network Quality of Service (QoS) to user Quality of Experience (QoE), which describes the overall performance of a network from the user perspective. High network QoS can, in many cases, result in high QoE, but it cannot assure high QoE. Optimizing end-to-end QoE must consider other contributing factors of QoE such as the application-level QoS, the capability of terminal equipment and customer premises networks, and subjective user factors. This article discusses challenges and a possible solution for optimizing end-to-end QoE in Next Generation Networks.

Feedback-based optimization of a private cloud

The optimization problem addressed by this paper involves the allocation of resources in a private cloud such that cost to the provider is minimized (through the maximization of resource sharing) while attempting to meet all client application requirements (as specified in the SLAs). At the heart of any optimization based resource allocation algorithm, there are two models: one that relates the application level quality of service to the given set of resources and one that maps a given service level and resource consumption to profit metrics. In this paper we investigate the optimization loop in which each application’s performance model is dynamically updated at runtime to adapt to the changes in the system. These changes could be perturbations in the environment that had not been included in the model. Through experimentation we show that using these tracking models in the optimization loop will result in a more accurate optimization and thus result in the generation of greater profit.

QoE assessment in haptic media, sound, and video transmission

In this article we investigate the effect of playout buffering control in haptic media, sound, and video transmission via QoE (Quality of Experience) assessment. We assess the operability of the haptic interface device, sound output quality, video output quality, inter-stream synchronization quality, and comprehensive quality. We also evaluate the application-level QoS (Quality of Service), and demonstrate that, with high accuracy, it is possible to estimate QoE parameters from QoS parameters.

On the Integration of Application Level and Resource Level QoS Control for Real-Time Applications

We consider a dynamic set of soft real-time applications using a set of shared resources. Each application can execute in different modes, each one associated with a level of Quality-of-Service (QoS). Resources, in their turn, have different modes, each one with a speed and a power consumption, and are managed by a Reservation-Based scheduler enabling a dynamic allocation of the fraction of resources (bandwidth) assigned to each application. To cope with dynamic changes of the application, we advocate an adaptive resource allocation policy organized in two nested feedback loops. The internal loop operates on the scheduling parameter to obtain a resource allocation that meets the temporal constraints of the applications. The external loop operates on the QoS level of the applications and on the power level of the resources to strike a good tradeoff between the global QoS and the energy consumption. This loop comes into play whenever the workload of the application exceeds the bounds that permit the internal loop to operate correctly, or whenever it decreases below a level that permit more aggressive choices for the QoS or substantial energy saving.

A New QoS Routing Scheme Based on Bandwidth Consumption for MANETs

Quality of Service (QoS) routing in Mobile Ad hoc NETworks (MANETs) is hard to achieve because the network topology tends to change constantly in a dynamic network. In this paper, we propose an effective QoS routing scheme to satisfy the required service demand and adapt to the dynamic changes in network resources. This novel approach of Application-Level QoS Routing Scheme (ALRS) comprises three significant features: (1) Estimation of consumed bandwidth on each node by using 2-hop neighbors' traffic information, (2) Route construction combined with admission control on each application session with (1), and (3) Route maintenance based on (1) and (2). By using our proposed ALRS scheme the availability of bandwidth is greatly improved for high-load communications, such as multimedia applications. By computer simulation we confirmed that ALRS increases the delivery ratio by up to 50% and decreases delay by less than one-fourth of the existing traditional method.

Quality-of-service trade-off analysis for wireless sensor networks

Quality of Service (QoS) support for wireless sensor networks (WSN) is a fairly new topic that is gaining more and more interest. This paper introduces a method for determining the node configurations of a WSN such that application-level QoS constraints are met. This is a complex task, since the search space is typically extremely large. The method is based on a recent algebraic approach to Pareto analysis, that we use to reason about QoS trade-offs. It features an algorithm that keeps the working set of possible configurations small, by analysing parts of the network in a modular fashion, and meanwhile discarding configurations that are inferior to other configurations. Furthermore, we give WSN models for two different applications, spatial mapping and target tracking, in which QoS trade-offs are made explicit. Test results for these applications and a heterogeneous WSN combining these two applications show that the models are accurate and that the method is scalable and thus practically usable for WSN, even with large numbers of nodes. Details are given on how to efficiently implement the algorithm.

Effect of TCP and UDP parameters on the quality of video streaming delivery over the internet

Delivering real-time video over the Internet is an important issue for many Internet multimedia applications. Transmission of real-time video has bandwidth, delay, and loss requirements. The application-level quality for video streaming relies on continuous playback, which means that neither buffer underflow nor buffer overflow should occur. Since the Best Effort network such as the Internet does not provide any Quality of Service (QoS) guarantees to video transmission over the Internet. Thus, mapping the application-level QoS requirements into network-level requirements, namely, limited delay jitters. End-to-end application level QoS has to be achieved through adaptation. Since the QoS of video streams over IP networks depends on several factors such as video transmission rate, packet loss rate, and end-to-end transmission delay. The objectives of this paper are to simulate an adaptation scheme to include the effect of User Datagram Protocol (UDP) parameters on delay jitter and datagram loss values to increase the efficiency of UDP protocol to prevent the network congestion and increase the adaptivity and also, simulate an adaptation scheme to include the effect of Transmission Control Protocol (TCP) parameters on the transmission rates to increase the adaptivity of the transmission.

Performance of beacon safety message dissemination in Vehicular Ad hoc NETworks (VANETs)

Currently, there is a growing belief that putting an IEEE 802.11-like radio into road vehicles can help the drivers to travel more safely. Message dissemination protocols are primordial for safety vehicular applications. There are two types of safety messages which may be exchanged between vehicles: alarm and beacon. In this paper we investigate the feasibility of deploying safety applications based on beacon message dissemination through extensive simulation study and pay special attention to the safety requirements. Vehicles are supposed to issue these messages periodically to announce to other vehicles their current situation and use received messages for preventing possible unsafe situations. We evaluate the performance of a single-hop dissemination protocol while taking into account the quality of service (QoS) metries like delivery rate and delay. We realize that reliability is the main concern in beacon message dissemination. Thus, a new metric named effective range is defined which gives us more accurate facility for evaluating QoS in safety applications specifically. Then, in order to improve the performance, the effects of three parameters including vehicle’s transmission range, message transmission’s interval time and message payload size are studied. Due to special characteristics of the safety applications, we model the relationship between communication-level QoS and application-level QoS and evaluate them for different classes of safety applications. As a conclusion, the current technology of IEEE 802.11 MAC layer has still some challenges for automatic safety applications but it can provide acceptable QoS to driver assistance safety applications.

IP MULTIMEDIA SUBSYSTEM - Application-Level QoS Negotiation and Signaling for Advanced Multimedia Services in the IMS

The IP multimedia subsystem (IMS) has been recognized as a reference next-generation network architecture for offering multimedia services over an Internet Protocol (IP)-based infrastructure. One of the key benefits of the IMS is efficient and flexible introduction of new services and access to third-party application providers, thanks to standard interfaces and standardized service capabilities. To support novel media-rich applications across a wide range of user devices and access networks, IMS must support negotiable quality of service (QoS) for IP multimedia sessions. In this article, we describe the application-level QoS signaling as specified by the 3GPP and propose some enhancements based on advanced QoS parameter matching and optimization functionality to be included along the signaling path. We outline various signaling flow scenarios and discuss them in the context of a case study involving an IMS-supported 3D virtual environment, featuring a treasure-hunt-like game.

Adaptive control of virtualized resources in utility computing environments

Data centers are often under-utilized due to over-provisioning as well as time-varying resource demands of typical enterprise applications. One approach to increase resource utilization is to consolidate applications in a shared infrastructure using virtualization. Meeting application-level quality of service (QoS) goals becomes a challenge in a consolidated environment as application resource needs differ. Furthermore, for multi-tier applications, the amount of resources needed to achieve their QoS goals might be different at each tier and may also depend on availability of resources in other tiers. In this paper, we develop an adaptive resource control system that dynamically adjusts the resource shares to individual tiers in order to meet application-level QoS goals while achieving high resource utilization in the data center. Our control system is developed using classical control theory, and we used a black-box system modeling approach to overcome the absence of first principle models for complex enterprise applications and systems. To evaluate our controllers, we built a testbed simulating a virtual data center using Xen virtual machines. We experimented with two multi-tier applications in this virtual data center: a two-tier implementation of RUBiS, an online auction site, and a two-tier Java implementation of TPC-W. Our results indicate that the proposed control system is able to maintain high resource utilization and meets QoS goals in spite of varying resource demands from the applications.

Design and Evaluation of a Cooperative Mechanism for Pure P2P File-Sharing Networks

To provide application-oriented network services, a variety of overlay networks are deployed over physical IP networks. Since they share and compete for the same physical network resources, their selfish behaviors affect each other and, as a result, their performance deteriorates. Our research group considers a model of overlay network symbiosis, where overlay networks coexist and cooperate to improve their application-level quality of service (QoS) while sustaining influences from the physical network and other overlay networks. In this paper, we especially focus on Peer-to-Peer (P2P) networks among various overlay networks. We propose a mechanism for pure P2P networks of file-sharing applications to cooperate with each other. In our proposal, cooperative peers establish logical links among two or more P2P networks, and messages and files are exchanged among cooperative P2P networks through these logical links. For efficient and effective cooperation, we also propose an algorithm for selection of cooperative peers and a caching mechanism to avoid putting too much load on cooperative peers and cooperating networks. Simulation results show that our proposed mechanism improves the search efficiency of P2P file-sharing applications and reduces the load in P2P networks.

Guest Editors' Introduction: Application-Level QoS

Application-level quality of service (QoS) is the Achilles' heel of services offered overthe Internet. The articles in this special issue cover various aspects of this complex problem, while exposing the challenges we have yet to overcome.

A Logic for Application Level QoS

Service Oriented Computing (SOC) has been proposed as a paradigm to describe computations of applications on wide area distributed systems. Awareness of Quality of Service (QoS) is emerging as a new exigency in both design and implementation of SOC applications.We do not refer to QoS aspects related to low-level performance and focus on those high-level non-functional features perceived by end-users as application dependent requirements, e.g., the price of a given service, or the payment mode, or else the availability of a resource (e.g., a file in a given format).In this paper we present a logic which includes mechanisms to consider the three main dimensions of systems, namely their structure, behaviour and QoS aspects. The evaluation of a formula is a value of a constraint-semiring and not just a boolean value expressing whether or not the formula holds. This permits to express not only topological and temporal properties but also QoS properties of systems.The logic is interpreted on SHReQ, a formal framework for specifying systems that handles abstract high-level QoS aspects combining Synchronised Hyperedge Replacement with constraint-semirings.

Effective Web browsing through content delivery adaptation

This article presents a Web content adaptation and delivery mechanism based on application-level quality of service (QoS) policies. To realize effective Web content delivery for users, two kinds of application-level QoS policies, transmission time and transmission order of inline objects, are introduced. Next, we define a language to specify these policies. We show that transmission order control can be implemented using HTTP/1.1 pipelined requests in which a client recognizes the transmission order description in a Web page and simulates parallel transmission of inline objects by HTTP/1.1 range requests. Experimental results show that our proposed mechanism realizes effective content delivery to a diverse group of Internet users. Finally, we introduce two methods to specify application-level QoS policies, one by content authors, and the other by end users.