广域DGNSS信息大规模实时播发系统研究

实践证明广域DGNSS(Differential Global Navigation Satellite System，DGNSS)可有效提高定位精度和完好性,但在高层建筑物较多的城市或室内,由于建筑物对卫星信号遮挡严重,根本无法实现高精度定位导航,通过互联网播发增强信息,有其独特的优越性。通过研究基于互联网的广域DGNSS(IBWD)的系统组成,并设计了其网络结构。将i3组播和基于IP路由信息表的应用层组播相结合,构建了基于节点异构性的分层混合组播网络。分析IBWD的结构特点,建立其网络模型,结果显示,IBWD具有较好的实时性和可扩展性,可以很好地满足导航增强信息在互联网上播发的应用需求。     

A Distributed Routing and Wavelength Assignment Algorithm for Online Muiticast in All-Optical WDM Networks

Routing and wavelength assignment for online real-time multicast connection setup is a difficulttask due to the dynamic change of availabilities of wavelengths on links and the consideration of wave-length conversion delay in WDM networks. This paper presents a distributed routing and wavelength as-signment scheme for the setup of real-time multicast connections. It integrates routing and wavelength as-signment as a single process, which greatly reduces the connection setup time. The proposed routingmethod is based on the Prim's MST (Minimum Spanning Tree) algorithm and the K-restricted breadth-first search method, which can produce a sub-minimal cost tree under a given delay bound. The wave-length assignment uses the least-conversion and load balancing strategies. Simulation results show that theproposed algorithm is suitable for online multicast connection establishment in WDM networks.     

一种基于邻近原则的应用层流媒体多播协议

提出了一种基于邻近原则的用于视频流直播服务的应用层多播协议.协议通过使用每个节点预生成的网络坐标信息,按照邻近原则调度的方法,构建一棵低延迟、低连接压力的层次化单源多播树,同时协议解决了真实网络中的部分服务能力限制问题,扩大了系统的可扩展性和可用性.     

DIASEAM:一种MPLS网络中新的组播转发机制

在多协议标签交换网络中，ATM标签交换路由器上的VC合并技术能够增强组播转发的扩展能力。为降低VC合并技术对附加缓存的需求，该文在SEAM转发机制的基础上提出了一种新的组播转发机制——动态标识符分配的SEAM转发机制DIASEAM（Dynamic Identifier Allocation SEAM）。通过为每个连接分配多个连接标识符，DIASEAM机制能够充分利用VPI／VCI标识符空间，大大节省ATM标签交换路由器的附加缓存。仿真结果表明：和基于传统VC合并技术的SEAM机制相比较，DIASEAM转发机制体现了更优越的性能，ATM-LSR附加缓存的需求和数据包的延迟显著降低。     

一种基于路由树的裁剪算法

多点广播技术已日益广泛应用到多媒体通信网络之中,多点广播路由策略是该项技术的关键部分。文章针对现有的多点广播路由策略存在的问题,提出了改进方法并给出了一种基于树型结构的冗余路由信息剪裁算法。     

Identity Based Group Key Agreement in Multiple PKG Environment

Secure and reliable group communication is an increasingly active research area by growing popularity in group-oriented and collaborative applications. In this paper, we propose the first identity-based authenticated group key agreement in multiple private key generators （PKG） environment. It is inspired on a new two-party identity-based key agreement protocol first proposed by Hoonjung Lee et al. In our scheme, although each member comes from different domain and belongs to different PKGs which do not share the common system parameters, they can agree on a shared secret group key. We show that our scheme satisfies every security requirements of the group key agreement protocols.     

Identity Based Group Key Agreement from Bilinear Pairing

0 IntroductionMulticast isthe core component of the groupcommunica-tions .There are several schemes proposed for securemulticast . The logical key hierarchy (LKH) was proposed byWonget al[1].Inthat ,the groupcontroller (GC) maintains alogical key tree where each node represents a key encryptionkey. An opti mizationthat haves the size of the rekeying mes-sages is described by Canettiet al[2]using a pseudo-randomgenerator tree(OFCT) . Another methodis the one-wayfunc-tion protocol (OFT)[3…     

A Dynamic Active Multicast Group Access Control Framework Based on Trust Management System

The current multicast model provides no access control mechanism. Any host can send data directly to a multicast address or join a multicast group to become a member, which brings safety problems to multicast. In this paper, we present a new active multicast group access control mechanism that is founded on trust management. This structure can solve the problem that exists in multicast members＇ access control and distributing authorization of traditional IP multicast.     

Distributed QoS multicast routing protocol in ad hoc networks

1 .INTRODUCTIONMobile ad hoc networks ( MANET) , also calledthe infrastructureless mobile network or self-or-ganized network,consists of a collection of mobilenodes sharing a wireless channel without any cen-tralized control or established communication back-bone .ad hoc networks have no fixed routers ;allnodes are capable of movement and can be connect-ed dynamically in an arbitrary manner . Usually ,these nodes act as both end systems and routers atthe same ti me . Nodes of these netwo…     

基于可用带宽的QoS多播路由算法

设计了一种基于时延、时延抖动和包丢失率3个QoS约束下的最大可用带宽多播树求解模型，将可用带宽作为主度量参数来构建多播树。能够针对特定的服务需求对各个QoS度量的重要性进行灵活调整。其算法具有多项式复杂度，并通过仿真证明了算法的有效性。