在IP上实现QoS

本文分析了IP网络上存在的QoS问题，介绍了其在第二层的实现，以及第三层实现的两种实现模型－综合服务模型和差别服务模型，在此基础上总结了其可能的实现模式，并分析了其特点，最后对IP网络上QoS的进一步发展作了展望。     

无线传感器网络中基于信息质量的跨层QoS支持

本文中提出了一种基于数据的信息质量而提供QoS支持的跨层协议,文中先阐述了无线传感器网络与传统网络在QoS支持上的不同的需求和特点,并提出了跨层优化的概念,指出无线传感器网络采用跨层优化的可行性和必要性.本文通过划分优先级来对网络提供不同的服务质量.数据包的优先级主要反应了数据包中所含的信息质量,由网络的应用层决定,而后再根据数据优先级的不同在MAC层提供不同的服务,从而实现跨层的QoS支持.     

无线传感器网络中基于信息质量的跨层QoS支持

本文中提出了一种基于数据的信息质量而提供QoS支持的跨层协议，文中先阐述了无线传感器网络与传统网络在QoS支持上的不同的需求和特点，并提出了跨层优化的概念，指出无线传感器网络采用跨层优化的可行性和必要性？本文通过划分优先级来对网络提供不同的服务质量．数据包的优先级主要反应了数据包中所含的信息质量，由网络的应用层决定，而后再根据数据优先级的不同在MAC层提供不同的服务，从而实现跨层的QoS支持。     

基于IP网络的服务质量（QoS）参数研究

QoS参数定义是实现QoS控制的基础,本文按照QoS的分层模型,针对IP网络上多媒体应用特点,提出了应用层、系统层和网络层三组QoS参数,并给出了部分参数的计算方法。     

无线Ad Hoc网络中QoS感知的跨层资源分配算法

在分析无线Ad Hoc网络资源分配模型的基础上,提出一种QoS感知的跨层资源分配算法CL-QARA (cross layer QoS aware resource allocation).其主要思想是,引入价格作为资源分配的度量指标,以QoS带宽需求为参数,将网络层的动态资源分配信息与MAC层CSMA/CA接入机制相结合,以改进MAC层的冲突退避算法.设计了改进的退避算法和呼叫接入控制算法,以实现MAC层与网络层的跨层技术.通过QoS感知的资源分配算法和跨层技术协同工作,为QoS服务提供了业务保障.仿真结果表明,CL-QARA算法具有良好的收敛性和稳定性.与其他算法相比,CL-QARA能够有效地提供QoS保证,提高了网络的效用和性能.     

基于Parlay APIs的QoS能力提供技术

针对支撑现代服务业的异构融合通信网络适配层对QoS能力的要求,设计基于Parlay APIs的QoS SCF接口,分析该接口在现代服务业中的应用。给出的QoS SCF接口能够保障网络切换时业务的连续性,实时反馈网络的资源使用状况,支持用户对QoS的偏好设置。仿真结果表明了该接口的功能实现。当网络负载较大时,在保证正常运行情况下,QoS SCF可以使业务吞吐量提高近50％。     

DiffServ over MPLS解决方案研究

介绍QoS模型DiiiServ及其实现,通过DiffServ对网络中的通信流量进行分类和策略控制来达到调节网络资源的目的.分析MPLS技术及其实现原理,将灵活的三层IP路由和高速的二层交换技术完美地结合起来;探讨了实现Dillserv与MPLS相结合的DiffServ over MPLS模型,从而实现网络中通信流量的QoS保证.     

业务驱动的无线多媒体传感器网络跨层优化

由于无线多媒体传感器网络链路动态变化、节点移动、带宽和能量受限等特点,传统的分层协议及其局部优化很难保证整个网络性能最优。为实现无线传感器网络中多媒体业务保障服务质量(QoS),提出一种基于业务驱动和自反馈机制的无线多媒体传感器网络跨层优化策略。该策略按照保证QoS等级最高业务服务质量原则,自适应优化网络协议栈各层参数,并将优化后参数反馈给相应网络协议层,实现保证QoS的网络资源优化,仿真结果表明,该方法在综合物理层误码率和链路层数据帧丢失率的情况下,与传统网络分层协义相比,提高多媒体信息传输质量方面有一定优越性。     

基于带宽代理的域内QoS控制

本文讨论了在区分服务的框架下，分层的QoS实现机制，即网络的QoS控制分为域间的QoS控制和域内的QoS控制。并着重考虑了在域内实现基于BB的QoS体系结构，它考虑了QoS路由、接纳控制、网络策略管理等因素，因此能实现良好的QoS保证并在网络域内部实现整体优化。     

基于SDN的网络传输QoS机制设计

随着工业控制、车载网络等实时业务流开始向以太网迁移,网络设备需要提供低时延低抖动的QoS保障机制。传统网络采用分布式控制,QoS保障机制的引入,会增加转发设备复杂度,同时也面临可扩展性问题。软件定义网络SDN通过将控制与转发分离,极大的增加了网络灵活性和可扩展性。本文基于SDN架构,通过在控制层将带宽资源量化为时隙,实现带宽资源的预分配;通过在转发层按时隙进行整形调度,避免了多条数据流同时到达中间转发节点产生的网络拥塞排队;通过从时间维度划分双通道传输,采用主动队列管理算法,隔离了普通通道对QoS通道的影响。本文充分利用SDN集中控制优势,设计了基于SDN的网络传输QoS机制,可为普通业务流与实时业务流等网络数据流传输QoS机制设计提供支持。     

园区网中QoS解决方案的研究

随着网络技术的发展,网络用户的增多以及各种大型实时的多媒体应用在园区网上实施,园区网在大学、公司和医院等企事业单位的生产和发展过程中发挥着越来越重要的作用,同时网络应用对网络服务的QoS提出更高的要求。本文介绍在园区网实施QoS方案的主要策略;分析DiffServ模型,DiffServ通过对园区网中的通信数据包进行分类和策略控制来达到调节网络资源的目的;探讨区分服务模型的实现,从而实现园区网的QoS保证。     

大型校园网QoS保障策略实现研究

本文比较了传统IP网络的QoS体系结构,通过分析IntServ和DiffServ两种模型的基本原理、工作方式,并指出其各自的优缺点和网络应用环境,设计了将扩展RSVP协议与DiffServ模型相结合的策略来保障大型校园网QoS的实现。仿真测试结果表明,此模型的应用可以有效地提升大型校园网络的QoS。     

A multi-layer experimental study of multimedia and QoS communication in wireless mesh networks

A significant issue in Mesh networks is to support multimedia transmissions while providing Quality of Service (QoS) guarantees to mobile users. For real-time multimedia streaming, unstable throughput or insufficient bandwidth will incur unexpected delay or jitter, and it remains difficult to provide comprehensive service guarantees for a wireless mesh environment. In this paper, we target the problem of providing multimedia QoS in wireless mesh networks. We design and implement a campus test-bed for supporting multimedia traffic in mobile wireless mesh networks, and investigate in detail some possible improvements on a number of layers to enable multimedia transmission over wireless networks with QoS support. We first study a number of improvements of some existing routing protocols to support multimedia transmissions. Some new admission control and rate control mechanisms are studied and their performance gains are verified in our experiments. In our new cross-layer adaptive rate control (CLARC) mechanism, we adaptively change the video encoder’s output bit rate based on the available network bandwidth to improve the quality of the received video. We also design a mobile gateway protocol to connect the MANET to Internet and a wireless LAN management protocol to automatically manage WLAN to provide some QoS.     

Quality of service: old idea, new options

ATM has offered QoS guarantees for nearly a decade, but the push is now for IP-based solutions. IP is ubiquitous in today's congested networks. Applications are more complex, users are more demanding, standards bodies are more receptive, and technology is more sophisticated. All this has focused attention on ways to add QoS to IP networks without exorbitant cost. But with progress has come some confusion. Telecommunications carriers and service providers are already enticing customers by offering two or three distinct classes of service over their IP networks. Vendors are beginning to ship QoS-capable hardware and software. ATM is firmly established in the Internet's core. A lot has happened in a short time, which means that users and providers must be aware of where things are going and what the various QoS technologies can actually do. Some QoS mechanisms deliver strict, absolute performance guarantees. Others merely offer assurances that one service class will take priority over another when resources are scarce     

域内QoS控制研究

针对目前在实际的IP网络中部署QoS面临的技术和政策等各方面的困难,本文在DiffServ的服务框架下,提出了一种分层的QoS实现机制,即将全网的QoS控制分为域间的QoS控制和域内的QoS控制.域内的QoS以Internet上的自治系统为一个相对独立的QoS"域"(如某个ISP、政府或学校的网络)来实现QoS控制,以满足QoS的增量部署要求,以及保持QoS机制的可扩展性(适应网络规模的变化)和技术进化要求.本文着重考虑了在域内实现基于带宽代理的QoS体系结构,这种体系结构综合考虑了QoS路由、接纳控制、网络政策管理等因素,因此能实现良好的QoS保证并在网络域内部实现整体优化.     

基于P2P的语言IP穿越网络地址转换和防火墙的统一模型

从P2P网络出发，提出了一种新的语言IP（Voice over IP，VoIP）穿越网络地址转换（Network Address Translation，NAT）和防火墙的统一模型。该模型利用分布式P2P网络的二层拓扑结构，通过最优路径建立算法（Optimal Path Establishment Algorithm，OPEA）以一种更有效的方式组织会话建立过程，使之能在各种情况下对NAT和防火墙的穿透问题提供最优解。与STUN等单一模型相比，具有更高的效率和健壮性。通过建立原型系统，在校园网环境中进行了模拟测试，证实了该模型的可行性以及提高服务质量的有效性。     

QoS-based media retrieval for networked digital archives

When digital multimedia data are retrieved from distributed digital archives, Quality of Service (QoS) criteria can be used to enhance the user's usability. In this paper, assuming best-effort networks as the infrastructure, we describe a multimedia (MM) retrieval method based on the QoS concept for MM data archives in heterogeneous communication environments. We introduce a multi-level QoS model and use response time, which is calculated based on a system-level QoS criterion, as an application-level QoS criterion. The order of retrieving MM data is determined, based on both key-word matching using key words specified by the user and the application-level QoS criterion. A prototype system is developed for retrieving sightseeing-related MM data including video, images, voice, and text. The proposed method of data retrieval has a shorter response time than methods that do not take QoS criteria into account. Also, a search method based on key-word association is described that enables wide-area search and effective information finding.     

AODV协议的选播QoS扩展研究与仿真

针对移动自组网(Ad hoc)的特点和AODV协议的可扩展性,提出了一种适合Ad hoc的选播QoS路由协议AQAODV,该协议在考虑选播路由特点的基础上,扩展AODV以支持QoS需求,并采用局部路由恢复技术,在动态变化的Ad hoc网中实现了一种高效的选播QoS路由.仿真结果表明,AQAODV协议在带宽、时延和平均路由开销等方面较AODV协议具有明显的性能优势.     

QoS based multicast routing algorithms for real time applications

In recent years, there has been a lot of interest in providing real-time multimedia services like digital audio and video over packet-switched networks such as Internet and ATM. These services require certain quality of service (QoS) from the network. The routing algorithm should take QoS factor for an application into account while selecting the most suitable route for the application. In this paper, we introduce a new routing metric and use it with two different heuristics to compute the multicast tree for guaranteed QoS applications that need firm end-to-end delay bound. We then compare the performance of our algorithms with the other proposed QoS-based routing algorithms. Simulations were run over a number of random networks to measure the performance of different algorithms. We studied routing algorithms along with resource reservation and admission control to measure the call throughput over a number of random networks. Simulation results show that our algorithms give a much better performance in terms of call throughput over other proposed schemes.