QoS for multimedia applications in satellite systems

We present a policy for handling multimedia traffic over satellite air interfaces. It extends the advantages of ATM to satellite by the statistical multiplexing of variable-rate traffic sources. Effectiveness is assessed within a multimedia satellite platform called EuroSkyWay, based on Ka-band payload and on-board processing     

Routing with multiple QoS requirements for supporting multimedia applications

Distributed multimedia applications usually require multiple QoS performance guarantees. However, in general, searching such a route in the network, to support multimedia applications, is known to be NPcomplete. In this paper, we propose a new heuristic QoS routing algorithm, called QoSR_DKS, for supporting multimedia applications in highspeed networks. QoSR_DKS is a modification of rulebased Fallback routing and Dijkstra algorithms. It can search a unicast route that would have enough network resources so that multiple QoS requirements (bandwidth, delay, and delay jitter) of the requested flow could be guaranteed. Its worst case computation time complexity is the same as that of the Dijkstra algorithm, i.e., O(V²), where V is the number of nodes in the network. Extensive simulations were done with various network sizes, upto 500 nodes networks, where each node uses Weighted Fair Queueing (WFQ) service discipline. Results show that QoSR_DKS is very efficient. It could always find the QoS satisfying route, whenever there exists one (success rate is optimal), and its average computation time is near to simple shortest path Dijkstra algorithm.     

Evolution of the Internet QoS and support for soft real-time applications

The past few years have witnessed the emergence of many real-time networked applications on the Internet. These types of applications require special support from the underlying network such as reliability, timeliness, and guaranteed delivery, as well as different levels of service quality. Unfortunately, this support is not available within the current "best-effort" Internet architecture. In this paper, we review several mechanisms and frameworks proposed to provide network- and application-level quality of service (QoS) in the next-generation Internet. We first discuss the QoS requirements of many of the above-mentioned real-time applications, and then we categorize them according to the required service levels. We also describe the various building blocks often used in QoS approaches. We briefly present asynchronous transfer mode (ATM) and Internet Protocol precedence. Then, we present and compare two service architectures recently adopted by the Internet Engineering Task Force, called integrated services (IntServ) and differentiated services (DiffServ), for providing per-flow and aggregated-flow service guarantees, respectively. We focus on DiffServ because it is a candidate QoS framework to be used in next-generation Internet along with multiprotocol label switching and traffic engineering. We also examine several operational and research issues that need to be resolved before such frameworks can be put in practice.     

QoS aware cross layer paradigm for urban development applications in IoT

Wireless Networks - Large number of services and heterogeneity of the objects have made Internet of Things (IoT) a complex paradigm. It is necessary to placate the requirements of quality of...     

QoS and multipoint support for multimedia applications over the ATMABR service

Multimedia applications with stringent delay requirements are usually supported by the constant bit rate (CBR) or real-time variable bit rate (rt-VBR) service categories of ATM. This article shows that the available bit rate (ABR) service, which was originally designed for data, can also support multimedia applications under certain circumstances. Issues related to the design of proper ABR traffic management algorithms for such support are presented     

QoS specification languages for distributed multimedia applications: a survey and taxonomy

Following considerable research into quality-of-service-aware application programming interface design and QoS specification language development for multimedia systems, we present a survey and taxonomy of existing QoS specification languages. As computer and communication technology evolves, distributed multimedia applications are becoming ubiquitous, and quality of service (QoS) is becoming ever more integral to those applications. Because they consume so many resources (such as memory and bandwidth), multimedia applications need resource management at different layers of the communications protocol stack to ensure end-to-end service quality, and to regulate resource contention for equitable resource sharing. However, before an application can invoke any QoS-aware resource management mechanisms and policies - such as admission control, resource reservation, enforcement, and adaptation - it must specify its QoS requirements and the corresponding resource allocations. Furthermore, the application must describe how QoS should be scaled and adapted in cases of resource contention or resource scarcity during runtime. Our goal in this article is to systematically classify and compare the existing QoS specification languages that span several QoS layers with diverse properties. The provided taxonomy and the extensive analysis will give us a detailed look at the existing QoS specification languages along with their properties and relations.     

An integrated resource negotiation, pricing, and QoS adaptationframework for multimedia applications

We study a dynamic, usage- and congestion-dependent pricing system in conjunction with price-sensitive user adaptation of network usage. We first present a resource negotiation and pricing (RNAP) protocol and architecture to enable users to select and dynamically renegotiate network services. We develop mechanisms within the RNAP architecture for the network to dynamically formulate prices and communicate pricing and charging information to the users. We then outline a general pricing strategy in this context. We discuss candidate algorithms by which applications (singly, or as part of a multi-application system) can adapt their rate and QoS requests, based on the user-perceived value of a given combination of transmission parameters. Finally, we present experimental results to show that usage- and congestion-dependent pricing can effectively reduce the blocking probability, and allow bandwidth to be shared fairly among applications, depending on the elasticity of their respective bandwidth requirements     

稳定服务质量水平的动态路由算法

本文介绍判定服务质量状态的质量水平涨落函数,以及与用户需求和服务资源变化相适 应的动态质量路由算法。仿真实验表明该算法具有稳定服务质量、平衡网络负载等特点。     

SIP的扩展在IMS QoS优化中的应用研究

基于SIP(会话初始协议)的IMS(IP多媒体子系统)的产生与发展,使得固网与移动网络的融合成为可能.为这种新型的网络提供多媒体业务的QoS(服务质量)保障是一个关键问题.根据SIP的简单、易扩展性,文章提出了一种利用SIP的扩展采改善IMS QoS的方案.     

QoS control by means of COPS to support SIP-based applications

The COPS protocol has been designed to enable communication on the interface between the policy decision administrator and the policy enforcement devices in a policy-based networking environment. It can be recognized that on the same interface there is the need to transfer information related to the request of resource by QoS clients and for the allocation of resources by resource allocation servers (e.g., bandwidth broker) in a DiffServ network. Hence, it is sensible to add this resource allocation functionality in the COPS framework. In particular, there are at least two cases where it is sensible to use COPS. The first case is on the interface between an edge node and a resource control node for handling resource allocation in a network provider domain. The second case is on the interface between a customer (client of a QoS enabled network) and the network provider: here COPS can be used as a protocol to signal dynamic admission control requests. In this article we present the definition of a new COPS client type to support the above-mentioned functionality, then describe an application scenario where SIP-based IP telephony applications can use Diffserv-based QoS networks. Simple backward-compatible enhancements to SIP are needed to interact with COPS/Diffserv QoS. A testbed implementation of the proposed solutions is finally described     

基于IP的下一代移动网络QoS方案

论述了移动网络中一种新的基于资源管理和预切换概念的QoS体系结构，并对该体系结构的信令接续过程和综合切换模型进行了具体分析。     

A QoS aware optimal node deployment in wireless sensor network using Grey wolf optimization approach for IoT applications

The growth of Wireless Sensor Networks (WSN) becomes the backbone of all smart IoT applications. Deploying reliable WSNs is particularly significant for critical Internet of Things (IoT) applications, such as health monitoring, industrial and military applications. In such applications, the WSN’s inability to perform its necessary tasks and degrading QoS can have profound consequences and can not be tolerated. Thus, deploying reliable WSNs to achieve better Quality of Service (QoS) support is a relatively new topic gaining more interest. Consequently, deploying a large number of nodes while simultaneously optimizing various measures is regarded as an NP-hard problem. In this paper, a Grey wolf-based optimization technique is used for node deployment that guarantees a given set of QoS metrics, namely maximizing coverage, connectivity and minimizing the overall cost of the network. The aim is to find the optimum number of appropriate positions for sensor nodes deployment under various p-coverage and q-connectivity configurations. The proposed approach offers an efficient wolf representation scheme and formulates a novel multi-objective fitness function. A rigorous simulation and statistical analysis are performed to prove the proposed scheme’s efficiency. Also, a comparative analysis is being carried with existing state-of-the-art algorithms, namely PSO, GA, and Greedy approach, and the efficiency of the proposed method improved by more than 11%, 14%, and 20%, respectively, in selecting appropriate positions with desired coverage and connectivity.

     

Precomputation schemes for QoS routing

Precomputation-based methods have recently been proposed as an instrument to facilitate scalability, improve response time, and reduce computation load on network elements. The key idea is, in effect, to reduce the time needed to handle an event by performing some computation in advance, i.e., prior to the event's arrival. Such computations are performed as background processes, enabling a solution to be provided promptly upon a request, through a simple, fast procedure. We investigate precomputation methods in the context of quality-of-service (QoS) routing. Precomputation is highly desirable for QoS routing schemes due to the high computational complexity of selecting QoS paths, and the need to provide a satisfactory path promptly upon a request. We consider two major settings of QoS routing. The first case is where the QoS constraint is of the "bottleneck" type, e.g., a bandwidth requirement, and network optimization is sought through hop minimization. The second is the more general setting of "additive" QoS constraints (e.g., delay) and general link costs. The paper mainly focuses on the first setting. We show that, by exploiting the typical hierarchical structure of large-scale networks, a substantial improvement can be achieved in terms of computational complexity. We consider networks with topology aggregation. We show that precomputation is a necessary element for any QoS routing scheme and establish a precomputation scheme appropriate for such settings. We consider the case of additive QoS constraints (e.g., delay) and general link costs. As the routing problem becomes NP-hard, we focus on /spl epsiv/-optimal approximations and derive a precomputation scheme that offers a major improvement over the standard approach.     

有线电视网络QoS体系

有线电视网络的业务多样性对QoS障提出了要求。本文提出了有线电视网络的QoS体系框架,并对相关的技术进行了介绍,包括HMS、DOCSIS、DQoS、IQoS等。     

分布式服务质量路由预计算算法

服务质量路由作为下一代IP互联网提供服务质量(QoS)控制的一种重要方案,如何提高其可扩展性和路由性能是有待解决的难题.本文提出了基于聚类的分布式预计算算法,以具有多种QoS参数的路由表预计算为目标,引入了支持QoS参数的扩展距离向量,通过网络中各个节点的分布式协同计算,大大降低了单个路由器的计算复杂度.文章分析了优势路径及其选取策略,给出了路由计算中优势路径聚集的聚类方法,实现了QoS路由表的高效聚集压缩.实验结果进一步验证了该算法具有计算量小和QoS路由性能高的优点,在QoS度量维数和网络规模方面均具有良好的可扩展性,并对域间算法研究提供了重要依据.     

Application layer QoS for videotelephony

Home broadband bandwidth will be a variable commodity as customers run multiple applications through their home hubs simultaneously. The reaction of some of these applications (e.g. Web browsing or e-mail) to congestion or packet loss will be governed by the control mechanisms within the transfer control protocol (TCP/IP). Retransmissions and rate control will slow down TCP applications when in a congested state, but data will, in general, be reliably transmitted. However, applications which are more sensitive to delay, such as voice over IP and videotelephony, are generally sent for delay considerations using the real time protocol (RTP) and the underlying unreliable user datagram protocol (UDP/IP). These protocols deliver timely data but with the downside that any congestion will lead to packet losses which will propagate up to, and need to be managed by, the application layer. This paper reports on efforts to define an application layer quality-of-service framework for the video component of videotelephony over RTP/UDP leading to an initial reference design for specifying videotelephony products. The error resilience features of the latest video-coding standard, H.264, are examined, as are modifications to existing RTP Internet recommendations to allow effective feedback-based repair for this new codec. Results using RTP early feedback and H.264 reference picture selection in a multi-reference configuration will also be presented.     

一种IP城域网的QoS解决方案

提出了一种IP城域网的QoS解决方案,允许网络运营商在不同的虚拟拓扑中承载不同的服务流量,这种区分虚拟拓扑结构能够保证不同的QoS水平.仿真结果表明:这种QoS管理模块以增加微小的阻塞率为代价,使EF流量有了更高的传输品质.     

面向SON的QoS重路由机制

随着计算机网络的发展,自组织网络因其具有灵活性、自适应性、顽健性等优点而受到广泛的关注。在OSPFv3协议的基础上,添加了QoS state交互报文,用于建立邻居信息表,进而完成链路上服务质量QoS的信息存储和重路由触发的判断,并引进了节点的休眠、苏醒等生物特性行为。为保证网络状态变化下应用的QoS,采用了混合式重路由机制,针对不同网络失效状况作出相应的处理。仿真实验表明,该路由机制具有良好的性能。     

Adaptively controlling the QoS of multimedia wireless applications through "user profiling" techniques

A large amount of research is currently focusing on the issue of the adaptive control of the quality-of-service (QoS) provided to multimedia applications in heterogeneous wireless systems. In this paper, the authors aim at contributing to this issue by proposing a mechanism that exploits user profiling techniques and suitable QoS mapping functions to introduce the soft QoS idea into a wireless multimedia scenario. The research objective is a QoS control architecture, which enables the continuous convergence between the actual user preferences and expectations and the resource constraints of the underlying wireless system. The proposed architecture operates between the system and the application layer. This allows it to achieve the intended results, by means of an effective dynamic reconfiguration of the applications and the contemporary renegotiation of the wireless resources.