电信级以太网QoS的解决思路与方案

根据运营商网络的特征．借鉴TDM、PSTN、同步网、三层交换、MPLS、RSVP等技术的思想,提出一种解决方案：通过定时优先调度算法,将IPN络带宽分为两部分,一部分为准同步带宽,用于传输有QoS要求的信息流,另一部分为普通带宽,用于传输一般的信息流。基于这个思路实现了实时业务流的中继带宽、严格CAC及随路资源确认。最后根据实时业务流的特征提出改进实时业务流交换算法的思路。     

提供电信级QoS的负载自适应时隙PQ算法研究

为解决实时业务流在IP网承载时遇到的高QoS参数与带宽公平性的矛盾,提出了一种负载自适应的时隙PQ(priority queue)算法.根据实时业务流的负荷参数,选择合适的触发周期τ转发实时业务流,将时延控制在要求的范围内,并大大减少了抖动,同时提高了非实时业务流的转发性能.通过理论推导与仿真证明了LASPQ (load-adaptive time slotted pfiority queue)在传输实时业务流时比PQ、WFQ等传统队列具有优越性.     

WiMAX实时业务数据下行调度算法的仿真与改进

WiMAX是下一代无线城域网(WMAN)技术,支持实时与非实时等多种业务,由IEEE 802.16协议定义.协议定义了多种QoS调度类型,但并没有定义具体的带宽调度策略,而WiMAX的下行相对于上行来说是更容易造成传输瓶颈.文章提出一种针对实时业务流的优化方案,BS进行下行调度时对实时业务集中调度,根据网络状况对分组进行动态丢弃,大大减少了在网络拥挤情况下的带宽使用和分组延迟,优化了抖动,保证了更好的QoS.文中以VoIP业务为例对NS2进行仿真.仿真结果表明,通过对下行分组队列算法的合理优化,能更好地改善系统性能、提高吞吐量、减少时延和减少缓冲区需求.     

一种认知网络中的带宽分配方法研究

认知网络作为一种新型的网络概念和技术,近年来其重要性得到了广泛的认同。在认知网络中,如何根据用户业务需求及带宽资源状况动态进行带宽分配是一个重要的问题。通过对用户权重的估计分析,提出了一种基于权重估计的改进带权Max-Min带宽分配算法,仿真试验证明该算法可改善对用户业务流QoS的整体保障能力。     

流媒体在分组传送光网络PTN传输的动态带宽分配算法

根据光网络由SDH向分组化PTN网络演进及新兴流媒体业务的特点,本文采用混合业务流模型,引入门限控制,多级选择丢弃和多级缓存优先级的概念,提出了一种基于业务分类和业务优先级的带宽分配算法-基于门限的动态优先级带宽分配方案（TDPBA）,克服了门限控制分配带宽颗粒过大和优先级算法运算量较大的弊病,在特别定制的试验平台上进行了四优先级系统的网络性能仿真,验证了此方案可以最大限度的保障高优先级业务的传输,可以用于对QoS有较高要求的业务,适合引入处在分组化进程中的光网络,在现有网络上更有效的承载流媒体业务.     

EDF调度算法在直通式交换以太网上的实现

提出了一种FTT(FleXible Time-Triggered communication paradigm)的改进调度模型.实现了周期性硬实时消息在基于成熟商用组件技术(COTS)的交换式以太网上的实时传输.并针对周期性实时消息在直通式交换以太网上传输提出了一种基于EDF的实时性调度算法.仿真实验表明该算法在提高网络的聚合带宽方面具有明显的优点.     

IEEE 802.16中改进的QoS动态分层调度算法设计

WiMAX(IEEE802.16)为每个节点提供实时业务和非实时业务,并对不同的业务提出了QoS保证服务。调度算法是WiMAX为分类业务提供QoS保证的重要技术。本文提出一种用于WiMAX系统PMP模式下的动态调整优先级的分层调度算法DAPQ,DAPQ算法由基站(BS)和用户站(SS)共同实现,为不同优先级的业务流动态分配带宽,可以为系统提供更好的公平性,并有效的减少时延。仿真结果表明,本文提出的算法在一定程度上降低了rtPS业务的时延和丢包率。     

基于多门限预留机制的自适应带宽分配算法

针对异构无线网络融合环境提出了一种基于多门限预留机制的自适应带宽分配算法,从而为多业务提供QoS保证。该算法采用多宿主传输机制,通过预设各个网络中不同业务的带宽分配门限,并基于各个网络中不同业务和用户的带宽分配矩阵,根据业务k支持的传输速率等级需求和网络状态的变化,将自适应带宽分配问题转化为一个动态优化问题并采用迭代方法来求解,在得到各个网络中不同业务和用户优化的带宽分配矩阵的同时,在带宽预留门限和网络容量的约束条件下实现网络实时吞吐量的最大化,以提高整个异构网络带宽的利用效率。数值仿真结果显示,所提算法能够支持满足QoS需求的传输速率等级,减小了新用户接入异构网络的阻塞概率,提高了平均用户接入率并将网络吞吐量最大提高40%。     

基于流媒体的实时网络传输系统中若干问题研究

流媒体在Internet上的实时传输常因其要求高带宽、低延迟而造成网络拥塞。探讨了基于Internet的实时流媒体中视频流的QoS控制策略,并主要论述了基于速率的网络拥塞控制方法并给出一种视频流编码速率调整算法。这些控制技术应用于终端系统并不需要路由器和网络QoS支持,可以较好地提高视频质量。     

基于动态最大传输窗口的带宽分配算法研究

数据业务和话音业务是未来网络中两个重要业务.作为下一代宽带接入的有效解决方案,以太网无源光网络(EPON)为用户提供了业务接口.对EPON中的上行带宽分配算法进行了分析研究,并提出一种基于动态最大传输窗口 DMTW 的 EPON 上行带宽分配算法.在本算法中根据业务和用户的优先级动态调整最大的传输窗口,合理分配上行带宽的资源,提高信道利用率和QoS,降低了传输时延.最后通过软件进行仿真,验证了算法的有效性.     

SDN-based architecture for providing quality of service to high-performance distributed applications

The specification of quality of service (QoS) requirements in most of the existing networks is still challenging. In part, traditional network environments are limited by their high administrative cost, although software-defined networks (SDNs), a newer network paradigm, simplify the management of the whole network infrastructure. In fact, SDN provides a simple way to effectively develop QoS provisioning mechanisms. In this sense, we explore the SDN model and its flexibility to develop a QoS provisioning architecture. Through the use of our new architecture, network operators are able to specify QoS levels in a simple way. Each individual data flow can be addressed, and the architecture we propose also negotiates the QoS requirements between the network controller and applications. On the other hand, the network controller continuously monitors the network environment. Then, it allocates network elements resources and prioritizes traffic, adjusting the network performance. We evaluate the feasibility of our QoS provisioning mechanism by presenting three experimental setups under realistic scenarios. For example, for a given scenario where we evaluate file transfers, our results indicate that the additional SDN modules present negligible overhead. Moreover, for a given setup, we observe a reduction of up to 82% in the file transfer times.     

数据业务端到端QoS参数映射与优化

在移动通信网内采用业务质量(QoS,Quality of Service)机制实现差异化的业务传输是近年的研究热点。端到端QoS包括非接入层用户和业务的识别、不同承载间QoS的一致性传递和接入层QoS的正确执行。这里以EDGE网络中数据业务传送机制为基础,全面研究了3GPP的QoS框架在UMTS网络的GERAN A/Gb模式和UTRAN Iu模式中的QoS映射,给出一个经过优化的端到端QoS参数映射表,并基于该表,在真实的EDGE网络中验证了QoS参数优化的可行性和参数映射的一致性。实验结果表明,根据不同业务的特点采用差异化的传输策略可以提升业务的感知。     

Quality of service in telecommunications .II. Translation of QoSparameters into ATM performance parameters in B-ISDN

The main goal of this article is to present the translation of quality of service (QoS) parameters between layers. The QoS parameters in the ATM layer and AAL are defined. This translation concept came from the QoS framework in which the influence of the protocol stack on the QoS should be considered. As an example, we concentrate on the translation from the AAL to the ATM layer, as the AAL must be designed to be service-dependent and specific. Translation, both taking the transport protocol into account as well as between application and transport QoS, needs further study. However, our study shows that the QoS translation is a possible and good approach in end-to-end QoS guarantees in the broadband integrated services digital network (B-ISDN). As far as the end-to-end QoS guarantee issue is concerned, the transport QoS requirements are specified in terms of bounds on transport QoS parameters. The bounds on transport QoS parameters will be translated into the bounds on ATM layer QoS parameters. The ATM-layer QoS parameters resulting from the translation will be the performance requirements on a connection basis for the ATM network, but are basically the end-to-end parameters, including the network and the end systems. Therefore, the QoS translation finally results in the network performance parameters in the ATM network. We define QoS parameters in the AAL and ATM layer. Case studies in which the translation method is applied to a constant bit rate (CBR) video service and data service, respectively, are also presented     

Quality of experience evaluation of HTTP video streaming based on user interactive behaviors

User interactive behaviors play a dual role during the hypertext transfer protocol (HTTP) video service: reflection and influence. However, they are seldom taken into account in practices. To this end, this paper puts forward the user interactive behaviors, as subjective factors of quality of experience (QoE) from viewer level, to structure a comprehensive multilayer evaluation model based on classic network quality of service (QoS) and application QoS. First, dual roles of user behaviors are studied and the characteristics are extracted where the user experience is correlated with user interactive behaviors. Furthermore, we categorize QoE factors into three dimensions and build the metric system. Then we perform the subjective tests and investigate the relationships among network path quality, user behaviors, and QoE. Ultimately, we employ the back propagation neural network (BPNN) to validate our analysis and model. Through the simulation experiment of mathematical and BPNN, the dual effects of user interaction behaviors on the reflection and influence of QoE in the video stream are analyzed, and the QoE metric system and evaluation model are established.     

Context-aware end-to-end QoS diagnosis and quantitative guarantee based on Bayesian network

To support quality of service(QoS)management on current Internet working with best effort, we bring forth a systematic approach for end-to-end QoS diagnosis and quantitative guarantee. For QoS diagnosis, we take contexts of a service into consideration in a comprehensive way that is realized by exploiting causal relationships between a QoS metric and its contexts with the help of Bayesian network(BN)structure learning. Context discretization algorithm and node ordering algorithm are proposed to facilitate BN structure learning. The QoS metric is diagnosed to be causally related to its causal contexts, and the QoS metric can be quantitatively guaranteed by its causal contexts. For quantitative QoS guarantee, those causal relationships are first modeled quantitatively by BN parameter learning. Then, the QoS metric is guaranteed to certain value with a probability given its causal contexts tuned to suitable values, that is, quantitative QoS guarantee is reached. Simulations with three sequential stages:context discretization, QoS diagnosis and quantitative QoS guarantee, on a peer-to-peer(P2P)network, are discussed and our approach is validated to be effective.     

A customizable QoS strategy for convergent heterogeneous wireless communications

This article proposes a general customizable QoS scenario for heterogeneous wireless access network technologies. The scenario provides robust and flexible QoS support by adapting the amount of resources reserved for the characteristics of the wireless channel, as well as automatic reconfiguration mechanisms of the multimedia encoding rate and error-resilient techniques to adapt to the dynamic mobile communication environment. Two new scenarios, adaptive FEC and MAC-Lite, are introduced to the proposed scheme. These enable a maximizing of the overall performance of the wireless network. The appropriate interfaces within the core network are described for performing end-to-end QoS, which deliver network meters and exchange QoS parameters with the proposed intra and inter cross-layer approaches, including context transfer during handover. Each part, extended by the proposed method can be configured by the application and be independently implemented. To evaluate the proposed scheme, the QoS components were integrated into a trial platform that was built and simulations were then performed. The results demonstrate that the communication quality was significantly improved     

The role of signaling in quality of service enabled networks

In this article we identify the common building blocks that enable some networks to provide better than best-effort transfer guarantees to the traffic they carry. We consider the role signaling plays in such a network and argue in favor of pinned routes, with a highly efficient pinning process, to improve network stability and to ease the task of maintaining QoS guarantees in the face of changing network characteristics, including failures; the use of broad QoS classes to determine the path that a particular flow should follow through the network; and providing the flexibility of specifying the detailed QoS for the flow, if needed, at any arbitrary time during the life of the flow. We conclude that a flexible signaling architecture is an essential enabling component of any QoS-aware network. We present an overview of the design and implementation of UNITE, as an example of a signaling architecture that embodies these attributes. More generally, we consider the relationship between QoS-related signaling and other protocols and mechanisms that may form part of an overall QoS-enabled network and service infrastructure     

Quality of service in telecommunications. I. Proposition of a QoSframework and its application to B-ISDN

The the quality of service (QoS) concept is becoming an ever more important issue in telecommunication and computer communication. The article focuses on the QoS notion and concept. The definition of QoS in the International Telecommunications Union-Telecommunications Sector (ITU-T) recommendations and the International Standards Organization (ISO) standards is analysed. Little is known about the asynchronous transfer mode (ATM) performance requirements of the broadband integrated services digital network (B-ISDN) services, especially for multimedia applications. This is because the ATM performance requirements of multimedia applications depend not only on the diverse QoS requirements from application and user, but also on the protocol stacks and scheduling in end systems. Therefore, in order to guarantee QoS to the user, it is necessary to introduce a set of QoS parameters whose properties indicate the nature and requirements of the layered protocol stack. We describe how a proposed QoS framework can be applied to B-ISDN as a specific network. The QoS aspects related to B-ISDN signaling (the control plane) and the QoS aspects related to layer and plane management (the management plane) are described. We also describe how the QoS framework resides in a protocol stack and works together with the B-ISDN network management and signaling     

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     

PRIN: A Priority-Based Energy Efficient MAC Protocol for Wireless Sensor Networks Varying the Sample Inter-Arrival Time

Wireless sensor networks (WSNs) are used in a variety of applications to sense and transfer information to the centralized node with energy efficiency increasing the network’s lifespan. Other factors, such as quality of service (QoS) is also important to improve the performance of the WSNs, by increasing throughput and reducing end-to-end delay. In this paper, we evaluate the importance of QoS in the Medium Access Control (MAC) protocol for WSNs using different metrics and parameters such as energy efficiency, throughput, delay, and the network lifespan. We propose a new QoS MAC protocol, “PRIority in Node” (PRIN), using static priority in the source and the intermediate node and priority among the node which is one hop from the sink node to achieve QoS in WSNs. Simulation results are compared with those of the synchronous MAC protocol in terms of QoS parameters to show the improved performance of the proposed MAC protocol.