A Hybrid Offline-Online Approach to Adaptive Downlink Resource Allocation Over LTE

Radio resource management mechanisms in current and future wireless networks is expected to face an enormous challenge due to the ever increasing demand for bandwidth and latency sensitive applications on mobile devices. This is because an optimal resource allocation scheme which attempts to multiplex the available bandwidth in order to maximize Quality of service (QoS), will pose an exponential computational burden at eNodeB. In order to minimize such computational overhead, this work proposes a hybrid offline-online resource allocation strategy which effectively allocates all the available resources among flows such that their QoS requirements are satisfied. The flows are firstly classified into priority buckets based on real-time criticality factors. During the offline phase, the scheduler attempts to maintain the system load within a pre-specified safe threshold value by selecting an appropriate number of buckets. This offline selection procedure makes use of supervisory control theory of discrete event systems to synthesize an offline scheduler. Next, we have devised an online resource allocation strategy which runs on top of the offline policy and attempts to minimize the impact of the inherent variability in wireless networks. Simulation results show that the proposed scheduling framework is able to provide satisfactory QoS to all end users in most practical scenarios.      

基于SaaS的弹性云平台优化调度策略设计

云计算平台利用虚拟化技术使软件应用变得更有效率的同时, 也给资源管理和服务调度带来了挑战。在研究了软件服务（SaaS）与基础设施服务（IaaS）调度的区别基础上, 重点考虑SaaS层的资源调度, 提出基于随机理论的调度模型, 把该层调度描述成一种多目标的优化问题。除了服务质量的要求, 还考虑了弹性这一云服务的重要特性, 并提供了任务调度与弹性服务副本的匹配策略。实验表明本调度机制的设计优化了云平台的整体性能, 达到了较好的负载均衡与资源利用率。     

Modelling and performance evaluation of the IEEE 802.11 DCF for real-time control

Popular wireless networks, such as IEEE 802.11/15/16, are not designed for real-time applications. Thus, supporting real-time quality of service (QoS) in wireless real-time control is challenging. This paper adopts the widely used IEEE 802.11, with the focus on its distributed coordination function (DCF), for soft-real-time control systems. The concept of the critical real-time traffic condition is introduced to characterize the marginal satisfaction of real-time requirements. Then, mathematical models are developed to describe the dynamics of DCF based real-time control networks with periodic traffic, a unique feature of control systems. Performance indices such as throughput and packet delay are evaluated using the developed models, particularly under the critical real-time traffic condition. Finally, the proposed modelling is applied to traffic rate control for cross-layer networked control system design.     

基于Xen虚拟化技术的弹性云架构

云计算通过虚拟化技术为用户提供基础架构即服务(IaaS),IaaS平台上应用和服务的负载是动态变化的,这就导致其对虚拟资源的需求也是动态变化的.因此收集和分析云平台内部虚拟资源的占用量,根据需求对其进行弹性调度就成为提高整个云计算平台服务性能和资源利用率的关键.从负载均衡和降低云平台使用者成本的角度出发,根据云平台内部...     

Quality of Service Support for Multimedia Applications in Third Generation Mobile Networks Using Adaptive Scheduling

Third generation mobile network will support services such as video-telephony, video-conferencing and other multimedia applications. Therefore, this network must provide quality of service (QoS) to these applications consistent with that offered by fixed networks. However, this is a very challenging task due to the instability of the wireless channel and the diverse quality of service requirements dictated by different multimedia applications. In this paper we introduce a resource allocation algorithm for the wireless downlink that takes into account the wireless channel characteristics, the QoS required by the applications as well as a pricing value function. Our solution is based on an adaptive scheduling algorithm originally developed for scheduling real-time processes during transient surges. This algorithm tends to maximize the wireless network operator profit while satisfying the customers' quality requests.     

SLA-based admission control for a Software-as-a-Service provider in Cloud computing environments

Software as a Service (SaaS) provides access to applications to end users over the Internet without upfront investment in infrastructure and software. To serve their customers, SaaS providers utilise resources of internal data centres or rent resources from a public Infrastructure as a Service (IaaS) provider. In-house hosting can increase administration and maintenance costs whereas renting from an IaaS provider can impact the service quality due to its variable performance. To overcome these limitations, we propose innovative admission control and scheduling algorithms for SaaS providers to effectively utilise public Cloud resources to maximize profit by minimizing cost and improving customer satisfaction level. Furthermore, we conduct an extensive evaluation study to analyse which solution suits best in which scenario to maximize SaaS provider?s profit. Simulation results show that our proposed algorithms provide substantial improvement (up to 40% cost saving) over reference ones across all ranges of variation in QoS parameters.     

Exploring vendor capabilities in the cloud environment: A case study of Alibaba Cloud Computing

Cloud computing is being viewed as an effective enabler for enhanced operational efficiency and flexibility in competitive business environments. Despite the increased knowledge on cloud computing, very few studies have been conducted to explore vendors' capabilities for service development and delivery. This gap prevents us from developing a full understanding of the service provision process and the actions through which vendors develop cloud services and create value for clients. In this paper, we present an in-depth qualitative case study of Alibaba Cloud Computing, China’s biggest Infrastructure-as-a-Service (IaaS) vendor, and identify five important capabilities, namely, cloud platform development, cloud platform deployment, IaaS imitation, IaaS commercialization, and IaaS improvement. We suggest that these capabilities and the associated actions are central to vendors’ adoption of cloud computing, acquisition of knowledge, and delivery and improvement of their cloud service provision. This paper contributes incrementally to the evolving scholarship on cloud computing and also offers useful guidelines for current and aspiring vendors.     

基于QoS的网格资源管理

资源管理是网格计算研究领域中的一项重要研究点,目前的研究工作大多致力于解决异构性问题,对于在交付无缝QoS(quality of service)前提下提高资源分配性能方面还缺乏深入的研究.而且,目前对网格QoS的研究集中于将多媒体网络QoS的相关成果融入网格体系架构中以提供对网格QoS的支持,而缺少对网格QoS的特性进行系统化的研究与归纳.为此,提出了网格QoS的层次结构模型,并对其中承上启下的虚拟组织层QoS参数进行了新的分类和测量;然后,利用SNAP(service negotiation and acquisition protocol)协议对基于网格QoS层次结构模型的网格QoS参数的映射转换过程进行了分析;最后,设计了网格资源管理仿真系统,并运用相关的网格QoS的研究改进了现有的Min-Min算法.仿真实验结果表明,基于QoS的网格资源管理可以在满足用户QoS需求下,有效地提高网格资源的利用率和服务请求的成功率.     

Failure-aware resource provisioning for hybrid Cloud infrastructure

Hybrid Cloud computing is receiving increasing attention in recent days. In order to realize the full potential of the hybrid Cloud platform, an architectural framework for efficiently coupling public and private Clouds is necessary. As resource failures due to the increasing functionality and complexity of hybrid Cloud computing are inevitable, a failure-aware resource provisioning algorithm that is capable of attending to the end-users quality of service (QoS) requirements is paramount. In this paper, we propose a scalable hybrid Cloud infrastructure as well as resource provisioning policies to assure QoS targets of the users. The proposed policies take into account the workload model and the failure correlations to redirect users’ requests to the appropriate Cloud providers. Using real failure traces and a workload model, we evaluate the proposed resource provisioning policies to demonstrate their performance, cost as well as performance–cost efficiency. Simulation results reveal that in a realistic working condition while adopting user estimates for the requests in the provisioning policies, we are able to improve the users’ QoS about 32% in terms of deadline violation rate and 57% in terms of slowdown with a limited cost on a public Cloud.     

A framework for establishing trust in the Cloud

Cloud infrastructure is expected to be able to support Internet scale critical applications (e.g. hospital systems and smart grid systems). Critical infrastructure services and organizations alike will not outsource their critical applications to a public Cloud without strong assurances that their requirements will be enforced. Central to this concern is that the user should be provided with evidence of the trustworthiness of the elements of the Cloud without getting involved into infrastructure details. In addition, users should be able to control their outsourced data at public Clouds. Establishing Cloud’s trust model is important but the Cloud’s infrastructure complexity and dynamism makes it difficult to address. This paper focuses on an important angle in this direction. We start by identifying the related challenges for establishing trust in the Cloud, and then propose a foundation framework which can help in addressing the identified challenges. Our focus is on IaaS Cloud type and on organizations as Cloud users.     

Real-time scheduling of divisible loads in cluster computing environments

Cluster computing has become an important paradigm for solving large-scale problems. To enhance the quality of service (QoS) and provide performance guarantees in a cluster computing environment, various real-time scheduling algorithms and workload models have been investigated. Computational loads that can be arbitrarily divided into independent tasks represent many real-world applications. However, the problem of providing performance guarantees to divisible load applications has only recently been studied systematically. In this work, three important and necessary design decisions, (1) workload partitioning, (2) node assignment, and (3) task execution order, are identified for real-time divisible load scheduling. A scheduling framework that can configure different policies for each of the three design decisions is proposed and used to generate various algorithms. This paper systematically studies these algorithms and identifies scenarios where the choices of design parameters have significant effects.     

A framework based approach to the development of network awareapplications

Modern networks provide a QoS (quality of service) model to go beyond best-effort services, but current QoS models are oriented towards low-level network parameters (e.g., bandwidth, latency, jitter). Application developers, on the other hand, are interested in quality models that are meaningful to the end-user and, therefore, struggle to bridge the gap between network and application QoS models. Examples of application quality models are response time, predictability or a budget (for transmission costs). Applications that can deal with changes in the network environment are called network-aware. A network-aware application attempts to adjust its resource demands in response to network performance variations. This paper presents a framework-based approach to the construction of network-aware programs. At the core of the framework is a feedback loop that controls the adjustment of the application to network properties. The framework provides the skeleton to address two fundamental challenges for the construction of network-aware applications: how to find out about dynamic changes in network service quality; and how to map application-centric quality measures (e.g., predictability) to network-centric quality measures (e.g., QoS models that focus on bandwidth or latency). Our preliminary experience with a prototype network-aware image retrieval system demonstrates the feasibility of our approach. The prototype illustrates that there is more to network-awareness than just taking network resources and protocols into account and raises questions that need to be addressed (from a software engineering point of view) to make a general approach to network-aware applications useful     

Hardware design and implementation of packet fair queuing algorithms for the quality of service support in the high-speed internet

The increasing amount of real-time traffic carried over the Internet requires end-to-end quality of service (QoS) support. To this end, the QoS Schedulers, that are implemented in routers, assign the available bandwidth resources to packet flows according to their respective allocated rates. Packet Fair Queuing (PFQ) schedulers can provide fair service and low end-to-end delay bound to the traffic flows. However, they have higher implementation complexity compared to other algorithms, because of the requirements of tracking the system state, and searching for the packet to get service among all flows, that are queued at the outgoing interface. QoS scheduling is a data plane functionality, which requires hardware implementation for high speed router interfaces. The previous works on hardware implementation of PFQ schedulers are specific to certain algorithms, and they do not provide any results on real hardware platforms. In this paper, we present a general hardware design framework for PFQ schedulers, and apply this framework to the WF²Q+ PFQ algorithm to demonstrate its properties. We carry out the entire implementation of the WF²Q+ algorithm on an FPGA, and evaluate its performance with real traffic flows. In addition, we implement WFQ as a second PFQ algorithm to demonstrate the generality of the framework.     

基于不确定参数的QoS路由研究

作为未来网络资源管理的一个重要组件，QoS路由问题越来越受到人们的重视。为了保证网络服务质量，希望根据多个QoS约束的尺度（metrics)来选择可行的路由。但由于网络本身的动态性和复杂性，网络状态信息具有固有的不确定性，因此有必要研究不确定参数对QoS路由的影响。通过形式化地描述基于带宽和延迟的不确定参数的QoS路由问题，给出了相应的处理模型和算法，并从实现的角度探讨了具有一定适应性的多路径QoS路由机制。     

基于FreeBSD内核的Chamber技术

服务质量支持技术和安全隔离技术是当前服务器操作系统研究领域的热点，也是服务器之间竞争的关键技术。该文分析了一些重要的资源控制技术，并结合这些技术提出了在FreeBSD操作系统中的QoS支持和安全隔离技术——FreeBSD Chamber(FC)机制。FC机制包括了上层的虚拟执行环境和底层的资源管理框架，提供完全隔离的执行环境和系统服务质量支持。     

An Approach to Quality of Service Management in Distributed Multimedia Application: Design and an Implementation

Most work related to quality of service (QoS) is concerned with individual system components, such as the operating system or the network. However, to support distributed multimedia applications, the entire distributed system must participate in providing the guaranteed performance levels. In recognition of this, a number of QoS architectures have been proposed to provide QoS guarantees. The mechanisms and schemes proposed by those architectures are used in a rather static manner since the involved entities, e.g., the network, sender and receiver, are known before the connection (call) set-up phase. In contrast to these architectures, we propose a general QoS management framework which supports the dynamic choice of a configuration of system components to support the QoS requirements for the user of a specific application. We consider different possible system configurations and select the most appropriate one depending on the desired QoS and the available resources. In this paper we present an overview of this general framework; especially, we concentrate on QoS negotiation and adaptation mechanisms. To show the feasibility of this approach, we designed and implemented a QoS manager for distributed multimedia presentational applications, such as news-on-demand. The negotiation and adaptation mechanisms which are supported by the QoS manager are specializations of the general framework. The proposed framework allows to improve the utilization of system resources, and thus to increase the system availability; it also allows to recover automatically, if this is possible, from QoS degradations. Furthermore, it provides the flexibility to incorporate different resource reservation schemes and scheduling policies, and to accommodate new system component technologies.     

IPv6下的DiffServ机制的研究与仿真

服务质量(QoS)对于Internet用户来说,是至关重要的I。Pv4网络的缺点之一就是缺少对QoS的支持,对所有通信应用都以尽力而为(Best Effort)的方式提供服务。对于一些实时性较强的应用(如视频会议等),无法对其特殊性给予保障。IPv6协议在吸取了IPv4教训的基础上,不仅解决了32位地址的局限,而且增加了OoS支持,端到端的安全机制,跳数限制等。本文主要针对IPv6下QoS中DiffServ机制的原理、架构及实施过程进行了研究,并且使用网络仿真软件OPNETModeler构建了DiffServ环境,进行了仿真试验。分别使用不同的排队机制进行试验,然后针对仿真结果进一步分析。     

A new fast friendly window-based congestion control for real-time streaming media transmission

1 Introduction In the current Internet, not all applications use TCP and they do not follow the same concept of fairly sharing the available bandwidth. The rapid growing of real-time streaming media applications will bring much UDP traffic without integrating TCP compatible congestion control mechanism into Internet. It threats the quality of service (QoS) of real-time applications and the stability of the current Internet. For this reason, it is desirable to define appropriate rate rule…     

QCWS: an implementation of QoS-capable multimedia web services

QoS (Quality of Service), which defines service quality such as latency, availability, timeliness and reliability, is important for web applications that provide real-time information, multimedia content, or time-critical services. Many web applications are best implemented by servers with a guaranteed server processing capacity. In this research, we study the QoS control issues using the current Web services standards. We propose a QoS-capable Web service architecture, QCWS, by deploying a QoS broker between Web service clients and providers. The functions of the QoS broker module include tracking QoS information about servers, making selection decisions for clients, and negotiating with servers to get QoS agreements. We have implemented a QCWS prototype using IBM WSDK, enhanced with simple QoS capabilities. We have measured the performance running under different service priorities.     

HeiRAT - Quality-of-service management for distributed multimedia systems

Multimedia systems must be able to support a certain quality of service (QoS) to satisfy the stringent real-time performance requirements of their applications. HeiRAT, the Heidelberg Resource Administration Technique, is a comprehensive QoS management system that was designed and implemented in connection with a distributed multimedia platform for networked PCs and workstations. HeiRAT includes techniques for QoS negotiation, QoS calculation, resource reservation, and resource scheduling for local and network resources.