基于服务器端会话追踪的Web查询服务的研究

在探讨了Web查询服务的典型模型后,论文阐述了服务器端会话追踪机制的实现方式,设计了基于服务器端会话追踪的Web查询服务的典型解决方案。该设计方案可以较为安全地保存和维护客户的上下文信息,可靠地跟踪用户查询所处的状态,有效地实现有状态的Web查询服务。     

多服务组的流媒体安全通信机制

提出了一种基于多服务组的流媒体安全通信机制.现有的方案一般是针对用户只参加一个多播组的通信,很少涉及到一个用户同时参加多个多播组的通信,而且没有提供有效的发送方身份验证机制.本文提出了一种具有发送方身份验证功能的一个用户同时可以参加多个组通信的方案,大大地降低了用户和服务器的存储开销,与传统的密钥树方案相比,用户的存储开销降低为原来的l/lgn(n为组中的用户数目),有良好的可扩展性.另外,本机制实现了可靠的发送方身份验证功能.     

基于SIP的宽带实时多媒体通信研究与实现

介绍了会晤创建协议(SIP)，提出了基于SIP的应用系统——SRMCS，针对该实时多媒体通信系统，分析了其音频模块的实现和背景噪音的处理、视频模块的实现和视频的流畅播放，并就实时多媒体通信系统的关键问题——视、音频同步给出了可行的解决方案，最后还探讨了本系统中信令流和媒体流的传输方式。     

Dynamic Multicast Session Provisioning in WDM Optical Networks with Sparse Splitting Capability

In this work, we study dynamic provisioning of multicast sessions in a wavelength-routed sparse splitting capable WDM network with an arbitrary mesh topology where the network consists of nodes with full, partial, or no wavelength conversion capabilities and a node can be a tap-and-continue (TaC) node or a splitting and delivery (SaD) node. The objectives are to minimize the network resources in terms of wavelength-links used by each session and to reduce the multicast session blocking probability. The problem is to route the multicast session from each source to the members of every multicast session, and to assign an appropriate wavelength to each link used by the session. We propose an efficient online algorithm for dynamic multicast session provisioning. To evaluate the proposed algorithm, we apply the integer linear programming (ILP) optimization tool on a per multicast session basis to solve off-line the optimal routing and wavelength assignment given a multicast session and the current network topology as well as its residual network resource information. We formulate the per session multicast routing and wavelength assignment problem as an ILP. With this ILP formulation, the multicast session blocking probability or success probability can then be estimated based on solving a series of ILPs off-line. We have evaluated the effectiveness of the proposed online algorithm via simulation in terms of session blocking probability and network resources used by a session. Simulation results indicate that our proposed computationally efficient online algorithm performs well even when a fraction of the nodes are SaD nodes.     

基于协议栈的移动性技术对比分析

传统的协议栈没有对实现移动性的层次进行准确定位，所以几乎协议栈中的每一层都有实现移动性的方案，但对于移动互联网这种异质网络。分层的协议栈效率很低。根据协议栈和移动互联网移动性的特点，从协议栈的链路层、网络层、传输层和应用层上具体分析了各个层实现移动性的优缺点，通过这些分析可见，要给移动互联网中的移动节点提供良好的移动性支持，跨层实现动性是未来移动性发展的趋势。     

Eliminating bandwidth estimation from adaptive video streaming in wireless networks

Dynamic Adaptive Streaming over HTTP (DASH) is the state-of-the-art technology for video streaming and has been widely deployed in both wired and wireless environments. However, mobile DASH users often suffer from video quality oscillation and even video freeze in wireless environments, which results in poor user experience. This is mainly because most quality adaptation algorithms in DASH rely highly on bandwidth estimation to adjust the video quality while wireless network bandwidth is unstable in nature and changes frequently according to wireless channel contention and condition. To provide stable performance, even during severe bandwidth fluctuation, this paper proposes the Wireless Quality Adaptation (WQUAD) algorithm, which eliminates bandwidth estimation from quality adaptation. Thanks to the Scalable Video Codec (SVC), the proposed scheme always prioritizes to lower layers over higher ones as long as the play-out buffer is not completely filled by the lower layers. As a result, the client always fills the buffer with the base layers first and then the upper enhancement layers sequentially. This horizontal adaptation is straightforward and does not require any bandwidth estimation. Through NS-2 simulations, we show that WQUAD achieves (i) stable performance, keeping the video quality level with respect to the long-term network bandwidth, (ii) effective video freeze prevention, and (iii) high video quality on average.     

一种适于HTTP数据还原的QS改进算法

为了更快速、准确地对HTTP应用数据进行还原,文中研究了改进的单模式匹配算法。对BM算法、BMH算法和QS算法进行了分析,并重点研究了QS算法的改进思路,最后提出了一种适用于HTTP应用数据还原的CIQS算法。CIQS算法考虑了HTTP模式串的字符特点,改进了模式串的字符比较顺序,并对坏字符跳跃思想进行了改进,增大了跳跃距离。实验结果表明,CIQS算法有效减少了匹配次数,相比其他几种算法有更好的时间性能。     

基于有线电视网络互动付费增值系统的设计

提出了基于有线电视网络和移动支付平台实现互动业务付费的设计方案,如电视收视费预交、最新大片点播、电费、天然气费的代缴、酒店预定、医疗服务预约等.通过该系统平台,让用户足不出户就能享受多种服务,扩展了传统有线电视的功能.该系统平台采用流行的J2EE框架-Struts+Spring+Hibernate来架构,采用分层式结构,从而降低了系统的耦合性,提高了系统平台的健壮性.系统平台自上线以来运行良好,建设该系统平台为新形势下有线电视开展多种多样的增值业务服务提供了一个范例.     

基于FH-AC系统Portal认证的实现与开发

随着当今移动互联网的快速发展,Wi Fi设备成为人们生活当中不可缺少的组成部分,而传统的无线网络在接入稳定性和安全性方面有待进一步提高。为了解决上述问题,设计了基于FH-AC系统的Portal认证系统。该系统通过对原有Portal协议进行改进并且采用Socket/HTTP通信和CHAP认证技术等一系列技术来提升系统性能,使整个系统在使用过程中能够更快更稳定地接入当前无线网络,其系统安全性也得到进一步的提升。     

基于BDS/GPS和百度地图的现代有轨电车监控系统的设计

为实现对现代有轨电车车辆的位置及运行状态进行实时监控,设计了一个基于BDS/GPS和百度地图的现代有轨电车监控系统;定位终端以具有我国自主知识产权的BDS/GPS双模定位模块为主,RFID系统作为辅助定位手段;数据通过HTTP的GET方法提交至服务器,由服务器端的PHP页面自动处理后存储到MySQL数据库,中心管理平台显示页面调用百度地图API,将数据显示在百度地图上;最终该系统可以实时获取并存储列车的位置坐标、速度、时间等信息,并在百度地图上以点、线和图表的形式显示出车辆的坐标和运行轨迹等;测试结果表明,该系统运行稳定,定位精度高,获取数据准确、时延小,能够满足应用需求。