High-level Quality Of Service Research Articles

A QoS-aware broker for hybrid clouds

Hybrid Clouds seems able to offer their customers with differentiate solutions capable of providing more and personalized guarantees with respect to the basic service availability generally supplied. In the context of an Italian research project aimed to transfer ICT advancements from research centers towards ICT SMEs, the paper focuses on the design of a brokering tool for hybrid clouds capable to adequately respond to specific Quality of Service (QoS) constraints. Aimed at satisfying the highest number of user requests while trying maximizing the profit of the private provider, in the context of a posted price economic model, the proposed brokering algorithm may apply different allocation policies, based on the reservation of a quota of private resources to high-level QoS applications.

High level QoS-driven model for Grid applications in a simulated environment

This paper presents a model for high-level Quality of Service (QoS) maintenance within business-context domains and associated simulation results achieved via an expansion of the GridSim toolkit. Grid Computing traditionally has been linked with scientific environments, where heterogeneous resources were networked and employed for carrying out compute-intensive and data-intensive scientific experiments or applications that may have not been possible before. The natural progression is that business-oriented applications will build on this success and utilise the large number of heterogeneous Grid resources, potentially available. The success of introducing these applications into the mainstream is directly related to whether Grid Resource Providers can deliver a suitable level of QoS to the Grid Resource Consumer (GRC) and the ability of the GRC to request high level QoS such as the numbers of CPUs required or the RAM required, on demand. Moreover, we present dynamically calculated metrics for measuring QoS such as reliability, using up-to-date information on resources. We introduce a novel model, Business Grid Quality of Service (BGQoS), for a new generation of commercial and business-oriented Grid applications which may wish to make use of Grid environments. BGQoS allows GRCs to specify varying types of high level QoS requirements which are delivered via querying up-to-date resource information, matchmaking and monitoring operations. In addition, testing is required and this has posed a problem where testing on physical Grid test-beds is either impractical or not viable economically. Simulation is therefore important.

Dynamic QoS Management and Optimization in Service-Based Systems

Service-based systems that are dynamically composed at runtime to provide complex, adaptive functionality are currently one of the main development paradigms in software engineering. However, the Quality of Service (QoS) delivered by these systems remains an important concern, and needs to be managed in an equally adaptive and predictable way. To address this need, we introduce a novel, tool-supported framework for the development of adaptive service-based systems called QoSMOS (QoS Management and Optimization of Service-based systems). QoSMOS can be used to develop service-based systems that achieve their QoS requirements through dynamically adapting to changes in the system state, environment, and workload. QoSMOS service-based systems translate high-level QoS requirements specified by their administrators into probabilistic temporal logic formulae, which are then formally and automatically analyzed to identify and enforce optimal system configurations. The QoSMOS self-adaptation mechanism can handle reliability and performance-related QoS requirements, and can be integrated into newly developed solutions or legacy systems. The effectiveness and scalability of the approach are validated using simulations and a set of experiments based on an implementation of an adaptive service-based system for remote medical assistance.

QoS-Guaranteed Power Control Mechanism Based on the Frame Utilization for Femtocells

The paper focuses on a power control mechanism and proposes a novel approach for dynamic adaptation of femtocells' transmitting power. The basic idea is to adapt the transmitting power of femtocells according to current traffic load and signal quality between user equipments and the femtocell in order to fully utilize radio resources allocated to the femtocell. The advantage of the proposed scheme is in provisioning of high quality of service level to the femtocell users, while interference to users attached to macrobase station is minimized. The paper proposes the power adaptation algorithm and evaluates its performance in terms of mobility events, achieved throughput, and FAPs transmitting power. Performed simulations show that the proposed scheme can significantly reduce the number of mobility events caused by passerby users and thus to minimize signaling overhead generated in the network. In addition, our proposal enhances overall throughput for most of the investigated scenarios in comparison to other power control schemes.

Enhanced throughput and QoS fairness for two-hop IEEE 802.16j relay networks

Frequency reuse among relay stations (RSs) in a down- link access zone is widely adopted for throughput enhancement in IEEE 802.16j relay networks. Since the areas covered by the RSs or the base station (BS) may overlap, some mobile stations (MSs) at the border between two neighboring transmitting stations (RS or BS) using an identical frequency band may suffer severe interference or outage. This co-channel interference within the cell degrades the quality of service (QoS) fairness among the MSs as well as the system throughput. Exclusive use of a frequency band division (orthogonal resource allocation) among RSs can solve this problem but would cause degradation of the system throughput. We observe a trade-off between system through- put and QoS fairness in the previously reported schemes based on frequency reuse. In this paper, we propose a new frequency reuse scheme that achieves high system throughput with a high fairness level in QoS, positioning our scheme far above the trade-off curve formed by previous schemes. We claim that our scheme is beneficial for applications in which a high QoS level is required even for the MSs at the border. Exploiting the features of a directional antenna in the BS, we create a new zone in the frame structure. In the new zone, the RSs can serve the subordinate MSs at the border and prone to interference. In a 3-RS topology, where the RSs are located at points 120° apart from one another, the throughput and Jain fairness index are 10.64 Mbps and 0.62, respectively. On the other hand, the throughput for the previously reported overlapped and orthogonal allocation schemes is 8.22 Mbps (fairness: 0.48) and 3.99 Mbps (fairness: 0.80), respectively. For a 6-RS topology, our scheme achieves a throughput of 18.38 Mbps with a fairness of 0.68; however, previous schemes with frequency reuse factors of 1, 2, 3, and 6 achieve a throughput of 15.24 Mbps (fairness: 0.53), 12.42 Mbps (fairness: 0.71), 8.84 Mbps (fairness: 0.88), and 4.57 Mbps (fairness: 0.88), respectively.

Hybrid power control scheme in hierarchical spectrum sharing network for cognitive radio

Recently, Hierarchical Spectrum Sharing Network (HSSN) has been proposed to efficiently and flexibly unitize available spectrum resource in cognitive radio context. In the HSSN, available spectrum bands are classified into two types to support both centralized and distributed communications simultaneously. A stable and efficient power control scheme is required to fully make use of the potential of HSSN. An effective power control scheme in the HSSN faces several challenges, such as low power emission, high level of quality of service (QoS), and suitability for the hybrid architecture of the HSSN. To effectively meet these requirements, a novel hybrid power control scheme is proposed in this paper. The proposed scheme is composed of three parts: a centralized power control scheme, a distributed power control scheme, and a coordination policy to coordinate these two types of power control schemes when both of them are exploited in the same channels. In the centralized power control design, we propose a Two-Step Fair Allocation (TSFA) scheme. In its first step, resources, such as channels and powers, are allocated by cognitive radio base station (CRBS) based on fairness and QoS requirements to obtain the maximum available resources of cognitive radio users (CRUs). In the second step, to get the final resource and reduce algorithm complexity, the allocation task is accomplished by each CRU simultaneously. In the distributed power control design, we propose Utility based Power Control algorithm combined with Admission Control (UPCAC). We also provide a protocol to effectively implement UPCAC. We formulate a utility function, i.e., payoff function minus price function, to measure the requirements of primary users (PUs) and CRUs. The payoff function represents CRUs’ signal-to-interference-plus-noise ratio (SINR) objectives, and the price function specifies protection for PUs and CRUs’ power consumptions. By analyzing the geometric characteristics of the payoff and price functions, we properly set the parameters of the utility function. Further, we propose coordination policy to combine centralized power control scheme with distributed power control scheme when they are exploited in the same channels. Simulation results show that the proposed hybrid power control scheme can meet the requirements of low emission power as well as high QoS level.

Adaptive quality of service management for enterprise services

In the past, enterprise resource planning systems were designed as monolithic software systems running on centralized mainframes. Today, these systems are (re-)designed as a repository of enterprise services that are distributed throughout the available computing infrastructure. These service oriented architectures (SOAs) require advanced automatic and adaptive management concepts in order to achieve a high quality of service level in terms of, for example, availability, responsiveness, and throughput. The adaptive management has to allocate service instances to computing resources, adapt the resource allocation to unforeseen load fluctuations, and intelligently schedule individual requests to guarantee negotiated service level agreements (SLAs). Our AutoGlobe platform provides such a comprehensive adaptive service management comprising —static service-to-server allocation based on automatically detected service utilization patterns, —adaptive service management based on a fuzzy controller that remedies exceptional situations by automatically initiating, for example, service migration, service replication (scale-out), and —adaptive scheduling of individual service requests that prioritizes requests depending on the current degree of service level conformance. All three complementary control components are described in detail, and their effectiveness is analyzed by means of realistic business application scenarios.

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.

On Recipe Based Service Composition in Ubiquitous Smart Spaces

We present a recipe based service composition scheme in smart spaces. We discuss real time problems of highly synchronized and user customizable processes with the help of an example. On-the-fly Quality of Service (QoS) shows up as a major issue in such environment. Furthermore the QoS of a dynamically composed service depends upon the aggregate QoS of its developing components. The dynamic composition of a service is done through the recipe file which is composed by service provider, it is like the control extension that checks the latest contest of the system from Context Servers and then generates the parameters for required services. Service Composition Manager is the entity that reserves the services from service pool and generates self management services. We setup context servers for context exchange and synchronicity of various processes. The generated service further takes the context from individual devices present in the area of influence and the effective use of context information helps us divide the complex jobs functionality into many simpler jobs on the bases of free time slots available per device. Each device performs its role and reports back to the context aware server and waits for new instruction in the next time slot. The principle objective is the presentation of system requirements of high level of QoS, required in delegating human centric ubiquitous applications. In the end we demonstrate our scheme with the help of an example and discuss its feasibility with the help of our model.

차별화 서비스망을 위한 정책 기반 서비스 품질 관리 모델

차별화 서비스(DiffServ)는 효율적이며 규모성을 갖는 방법으로 서비스 품질(QoS)을 제공하는 기술이다. 그러나, 현재의 차별화 서비스 규격들은 완전한 QoS 관리 프레임워크와 구현 모델의 제공에는 취약한 실정이다. 본 논문은 차별화 서비스 망의 QoS를 관리하기 위하여 차별화 서비스 정책을 지원하는 정책 기반 차별화 서비스 QoS 관리 모델을 제안한다. 이 모델을 모델-뷰-컨트롤러(MVC) 구조를 따르며, EJB(Enterprise JavaBeans) 기술에 기반을 두고 있다. 우리의 모델에서 상위 레벨 차별화 서비스 QoS 정책들은 XML 스키마를 갖는 유효한 XML 문서들로 표현되고 EJB 기반 정책 서버 내에 하위 레벨 EJB 정책 번들로 변환된다. QoS 정책을 정의하기 위해 필요한 라우팅 형상과 라우터의 역할 정보 검출은 SNMP MIB-II를 사용하고, QoS 정책 분배와 모니터링은 SNMP DiffServ MIB를 사용한다. Differentiated Services (DiffServ) is a technique to provide Quality of Service (QoS) in an efficient and scalable way. However, current DiffServ specifications have limitations in providing the complete QoS management framework and its implementation model. This paper proposes a policy-based QoS management model that supports DiffServ policies for managing QoS of DiffServ networks. The management model conforms to Model-View-Controller (MVC) architecture, and is based on Enterprise JavaBeans (EJBs) technologies. In our model, high-level DiffServ QoS policies are represented as valid XML documents with an XML Schema and are translated to low-level EJB policy beans in the EJB-based policy server. The routing topology and role information required to define QoS policies is discovered by using SNMP MIB-II, and the QoS policy distribution and monitoring is accomplished by using SNMP DiffServ MIB.

A Model for Availability of Quality of Service in Distributed Multimedia Systems

In this paper we introduce a new model for the definition and the implementation of quality of service (QoS) in distributed multimedia systems. The model provides both the users and the provider/manager of the system with a framework for the high level description of the system's configuration and operation, as well as with an application/user specific definition of QoS. The model maps this high level QoS description to quality requirements for the individual resources that compose the overall service. The implementation of the QoS of the overall service is done by providing probability of availability guarantees for certain levels of QoS. Given some constraints on the total assets available for the implementation of a specific service, the model optimally allocates these assets to the system resources in order to implement a specific user/application QoS profile. The model is reduced to a General Asset Allocation Problem (GA2P) and we solve the GA2P in a provably optimal way for a wide range of realistic services.

Alternative Transport Architecture for Core ATM Networks

In order to remain competitive in an increasingly aggressive market-place, it is essential that network operators deliver cost-effective, resilient bulk transport. This will enable the unit costs of circuit delivery in the core network to be reduced, while assuring high-level quality of service. In particular, the growth in advanced data services which exploit ATM technology will place significant demands on the core transmission layer of telecommunications networks. This paper investigates alternative transport architectures for core ATM networks.