面向用户的IMS媒体层统一安全框架

针对IMS媒体层安全保护机制存在的问题,提出一个面向用户的IMS媒体层统-安全框架,在此基础上设计了具体的实现方案,该方案能为用户提供灵活的媒体层安全保护机制,实现媒体层加密算法与密钥的安全协商,保证用户之间端到端的通信安全。实验结果证明了该方案的有效性。     

基于链接成本反馈的WiMedia分布式路由协议

在超宽带(UWB)分布式媒体访问控制协议中,DRP预留块未发送所有数据帧会导致中继设备无法将接收到的数据帧从源设备发送到目的地设备,直到为目的地设备预留的下一个DRP持续时间开始,明显增加了源设备和目标设备之间的端到端延迟。为此,提出一种新的基于预约的路由协议,设计链接反馈信息元素结构形式,提示关于相邻节点的数据速率和传输功率水平的信息,所有设备可获得关于相邻设备使用链路的数据速率信息,源设备和目的地设备之间的中间设备通过计算路由成本以确定最佳路由,目的地设备选择具有最小链路成本的路由,并利用媒体接入时隙的数量和跳数来决定源设备和目的地设备之间的最佳路由。仿真结果表明,该协议通过最小化丢包和冲突,可以减少端到端延迟和能量消耗,提高网络吞吐量。     

基于视频发送端速率控制的QoS技术研究

基于尽力而为的网络模式不能提供QoS保证,网络拥塞和分组丢失不可避免。在端到端视频单播结构下,论文提出了一个发送端速率控制框架SRCF,在此框架下首先利用RTCP报文中的字段提出了一种网络参数测量方法,然后设计了一个自适应速率算法SRCA,SRCA利用已得到的网络传输延迟和分组丢失率参数作为初始参数,来调整编码速率,达到充分利用带宽的目的,避免了视频质量由于调整参数带来的剧烈抖动。仿真结果表明,该算法在网络出现一定拥塞的条件下,能跟踪带宽的变化,网络和媒体QoS能保证视频质量较好。     

微软将推出WindowsAzure媒体服务平台

日前,微软在拉斯维加斯的NAB展会上揭开了其最新打造的“端到端”数字媒体服务平台——WindowsAzure媒体服务（Windows Azure Media Services）的神秘面纱。微软的媒体平台之前就支持多种编码、多台连接网络设备上的媒体传输和播放。     

一种直播服务器的设计与实现

提出一种直播服务器设计方案,媒体接收端根据节目链接访问媒体源,获取媒体数据流;媒体数据缓冲区是一个双循环缓冲区,循环缓存媒体接收端获取的媒体数据流;媒体服务器发送端根据媒体数据缓冲区建立子会话,生成访问该节目的直播服务器链接,终端通过链接访问直播服务器,直播服务器从媒体数据缓冲区中循环读取媒体数据发送给终端。设计方案具有适合多种网络、架设过程简单、可多台服务器级联等特点,并且成本低廉,可扩展性强。     

一种直播服务器的设计与实现

提出一种直播服务器设计方案,媒体接收端根据节目链接访问媒体源,获取媒体数据流;媒体数据缓冲区是一个双循环缓冲区,循环缓存媒体接收端获取的媒体数据流;媒体服务器发送端根据媒体数据缓冲区建立子会话,生成访问该节目的直播服务器链接,终端通过链接访问直播服务器,直播服务器从媒体数据缓冲区中循环读取媒体数据发送给终端。设计方案具有适合多种网络、架设过程简单、可多台服务器级联等特点,并且成本低廉,可扩展性强。     

“数字媒体工厂”现身

3月11日,IBM公司发布最新解决方案——“数字媒体工厂”,“数字媒体工厂”的特点是为数字媒体提供了“端到端”的解决方案,为各个行业企业管理、存储、保护和分发视频、音频和图像等多种数字内容提供了框架。在数字媒体工厂的整体框架下,包含了IBM的DB2数据库、中间件、IntelliStation 工作站、eServer服务器、企业存储设备、内容管理和发布软件,并     

基于分段氨基酸组成预测β-琼胶酶的最适温度

为了探究氨基酸组成对β-琼胶酶催化底物时的最适温度的影响,分别统计分析了酶全长、N端、M段及C端序列中20种氨基酸出现的频次。以支持向量机回归构建了氨基酸组成与β-琼胶酶最适温度的模型,10-倍交叉验证获得最小平均绝对误差(MAE),线性核函数的M端为4.36℃,RBF核函数的M端为4.16℃,独立样本测试得到N端的MAE分别为3.12℃和4.43℃。上述结果表明,该酶N端和M端是影响其最适温度的重要因素。通过比较最适温度为60℃和30℃β-琼胶酶的高级结构,推测M端和N端中3个螺旋结构是影响该酶最适温度的重要因素。     

基于输入端无冲突算法的面向输出排队的交换结构

该文提出了一种全新的面向输出排队的交换结构,该结构将信元存储于输入端,而信元的调度请求面向输出端排队.利用输入端无冲突调度算法,可以使结构对存储器带宽的需求和输入排队交换机一致.该文设计的调度矩阵使算法复杂度和端口规模呈线性关系,且每一步只需要一次按位"与"操作.文章同时证明了结构要达到稳定的充分条件是使用2倍传输加速比.仿真实验表明,对于均匀流量,该结构时延性能和主流交换结构相似,且抖动性能远优于主流交换结构,而在2倍传输加速比时,其时延性能和OQ完全相同;对于非均匀流量,该结构吞吐率性能优于主流交换结构,且在使用1.14倍传输加速比时,其吞吐率性能和OQ相同.     

基于网络的媒体流同步算法

分析了网络中多媒体传输同步的基本问题,在包交换网络基础上,提出了一种计算单媒体流的端到端延迟、缓冲区大小的方法,而且分析了源端和目的端时钟不同步问题。     

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.     

Scalable multimedia delivery with QoS management in pervasive computing environment

People are increasingly demanding rich-media and bundled services. However, the diverse terminals, heterogeneous networks as well as various user requirements constrain the multimedia access to low quality in the pervasive computing environment. In order to enable rich-media delivery across a wide range of devices and networks, multimedia adaptation with scalable QoS management is an important issue. Our research introduces a Scalable Multimedia Delivery (SMD) framework with QoS management. This framework utilizes the CAM4Home metadata model to aggregate multimodal rich media services into a bundle. MPEG-21 metadata is integrated into the CAM4Home model to enforce interoperable QoS management. The issues in supporting QoS are addressed on both fidelity and modality. We further develop the SMD system in IP Multimedia Subsystem (IMS) architecture, where multimedia adaptation is implemented through application-level QoS negotiation.     

基于业务区分的无线多媒体传感器网络QoS体系结构

无线多媒体传感器网络（WMSNs）的网络服务质量（QoS）一直是人们关心的核心问题,然而目前WMSNs的QoS保障研究主要针对单个协议层或特定应用场景,缺少系统性的QoS体系框架研究。结合无线传感器网络自身特点,利用图论对网络进行建模。在此基础上,提出一种三层可计算QoS指标体系,并根据各种应用不同QoS需求将应用分为四类,设计出一种基于业务区分的无线多媒体传感器网络QoS体系结构（DQoSAW）。以传输MPEG视频流为例对DQoSAW进行验证,实验结果表明DQoSAW能够显著改进WMSNs的整体性能。     

基于网格的流媒体服务QoS管理框架及实现

流媒体服务是Internet上一类高带宽需求和高实时性约束的应用，对服务质量（Quality of Service，QoS）有较高的要求。流媒体服务的发展导致传统的QoS管理框架难以适应平台的异构性和复杂性。本文提出了一种基于网格的流媒体服务QoS管理框架，为由异构的系统构成的流媒体服务提供集成的、平台无关的QoS管理机制。在谈框架的基础上，我们设计了一个基于网格的流媒体服务QoS管理系统。     

QoS获益驱动的中间件调度框架研究

Web应用服务器目前普遍采用的先到先得式(FCFS)的调度框架在过载时难以保障应用的服务质量(QoS)需求.QoS获益驱动(QBD)的调度框架是一种针对这些不足而提出的请求调度解决方案.QoS获益根据应用的QoS需求得到,用于评价QoS保障对应用需求的满足情况.QBD调度框架包含了多个用于保障应用QoS需求的组件,实现了基于QoS获益的资源规划算法,能够提高服务器对应用QoS需求的保障能力.在OnceAS平台上的实验结果验证了QBD调度框架的有效性.     

QoS-adaptive bandwidth scheduling in continuous media streaming

In this paper, we present a QoS-adaptive admission control and resource scheduling framework for continuous media (CM) servers. The framework consists of two parts. One is a reserve-based admission control mechanism in which new streams, arriving during periods of congestion, are offered lower QoS, instead of being blocked. The other part is a scheduler for continuous media with dynamic resource allocation to achieve higher utilization than non-dynamic schedulers by effectively sharing available resources among contending streams and by reclamation which is a scheduler-initiated negotiation to reallocate resources among streams to improve overall QoS. This soft-QoS framework recognizes that CM applications can generally tolerate certain variations on QoS parameters; that is, it exploits the findings about human tolerance to degradation in quality of multimedia streams. Using our policy, we could increase the number of simultaneously running clients that could be supported and could ensure a good response ratio and better resource utilization under heavy traffic requirements. Our admission control and scheduling strategy provides three principle advantages over conventional mechanisms. First, it guarantees better total system utilization. Second, it provides better disk utilization and larger admission ratio for input CM streams, which is a major advantage. Third, it still presents acceptable play-out qualities compared to the conventional greedy admission control algorithm.     

QoS图像自动处理模型设计

首先提出了结合QoS和自动图像处理的网格系统设计模型,本模型采用基于语义的高级请求分解并自动生成工作流,通过处理网格服务QoS属性的匹配处理过程,在满足QoS需求前提下找到最优服务组合。之后对模型主要模块进行详细分析,最后通过一个实验证明了模型在服务组合调度上的有效性。     

QoS Filtering and Resource Reservation in an Internet Environment

Multimedia group applications often operate in an environment where the various participants are located on systems and communication links with different capabilities. Mechanisms are required that ensure full-quality media for high-performance workstations but lower-quality media for playout at low-end systems. QoS filters have been proposed as a way to adapt QoS to the user specified level by changing the structure of a media stream in a well defined way. Resource reservation and QoS filter instantiation should be closely integrated since both represent one particular aspect of the provision of individualistic QoS for heterogeneous users in multipeer communications. The Internet reservation protocol RSVP is receiver oriented and allows each receiver to specify its resource requirements. However, no actual mechanisms are defined that adapt the data stream to the receiver specified QoS requirements.In this paper we present an enhanced version of RSVP (called RSVP++) that integrates resource reservation and QoS filter control. In order to achieve this integration we extend the RSVP functional model and define a new QoS service class. RSVP++ can coexist with common RSVP systems, thus, openness and interoperability of the system are ensured.     

LTE网络中具备QoS保障的动态负载均衡算法

研究了3GPPLTE网络中考虑不同服务质量(quality-of-service,QoS)要求的动态负载均衡算法.小区间的负载不均衡对于不同QoS要求用户有不同负面影响.对于有保障速率要求的用户,负载不均衡会导致较高的新呼叫阻塞率;而对于那些没有速率要求的用户,负载不均衡会导致繁忙小区中边缘用户过于恶化的吞吐量.全网中这两类用户的负载均衡问题紧密耦合,难以用一个统一的目标函数来分析研究.因此提出一个相应的多目标优化问题,其目标函数分别是针对全网内有QoS要求用户的负载均衡指示函数和针对全网内没有QoS要求用户的总效用函数,限制条件为实际小区物理资源和用户QoS要求.对该问题的复杂度进行了分析后,提出了一个实时的低复杂度低开销的分布式负载均衡算法结构,包括QoS保障的混合调度,QoS感知的负载均衡切换和呼叫准入控制.最后,系统级仿真结果显示提出的全新的负载均衡算法结构达到了较好的负载均衡效果,可以显著降低有QoS要求用户的新呼叫阻塞率,同时以略微损失全网无QoS要求用户总吞吐量的代价大幅提升繁忙小区中边缘用户的实际吞吐量.     

服务质量(QoS)控制技术的相互映射

随着因特网上多媒体业务的不断增长,端到端的QoS技术变得越来越重要。区分服务是因特网上最有希望得到实现的一种QoS技术。该文介绍了区分服务与综合服务、ATM和MPLS的相互映射问题,提出了一些解决方案。