卫星集群IP多播组呼业务协议研究

现有集群通信覆盖范围有限,为实现全方位集群通信,提出将卫星通信与集群通信相结合。以TETRA为例,分析了现有国内外集群通信系统集群业务的实现方式。针对电路域集群,提出实现分组域多媒体集群。为更利于工程实现,提出了基于MBMS技术的卫星集群IP多播组呼业务协议流程,并分析了实现中需要解决的关键问题及解决方案。该方案将为卫星移动通信集群业务的发展提供新的方向。     

实现手机电视的技术方式

DVB-H手机电视技术从传统的数字电视技术演进而来并广泛应用于3G移动通信中。回顾数字电视技术的发展历史,比较基于手机的流媒体业务、MBMS、DVB-H、MediaFLO和DVB-S不同调制方式的数字电视技术的优缺点,并分析5种传输系统在不同网络环境中的运行性能。     

Recent developments in synchrotron vacuum ultraviolet photoionization coupled to mass spectrometry

In recent years, increasing attention has been paid to “soft” photoionization (PI), which will potentially become a standard, universal ionization method. Tunable synchrotron vacuum ultraviolet (SVUV) light, a quasi-continuous light with good energy resolution and high photon flux, has proved an ideal source for “soft” PI in various research fields (e.g., combustion chemistry and molecular imaging).This review focuses on combinations of SVUV light with commonly used techniques (e.g., molecular-beam sampling, laser desorption, ion desorption, and thermal vaporization). These couplings have successful applications in flame chemistry, organic analysis, chemical imaging and aerosol mass spectrometry.     

TD-MBMS物理层方案研究

第三代移动通信技术TD-SCDMA发展至今,R4,R5已经商用普及,手机电视业务的需求更加强烈,对MBMS提出了更高的要求,基于MBMS的技术要求,通过借用cost231_hata模型的市区环境,分别对SFN检测技术和联合检测两种宏分集技术进行测试仿真,得到了两种宏分集的的优缺点,并提出改进方案。     

一种有效的MBMS业务调度方法

由于无线链路的容量受限,广播组播信道需要更加科学的调度机制,以便充分地利用无线资源。文章在综合考虑CN业务调度、RAN业务调度策略以及反馈机制的基础上,提出了一种有效用于MBMS业务的端到端调度方法,并给出了业务调度的仿真分析。该方法包括从所有实体中分离调度子功能的分配方法、反馈策略以及架构的演进。     

MBMS业务中的解密算法的研究

MBMS移动多媒体广播/组播业务,基于广播业务的一对多的特性,为了保证数据传输过程的保密性,流媒体传输过程的安全问题已受到普遍关注.一个具有安全保护功能的RTP协议即SRTP协议系统的实现不仅有利于对抗网络安全攻击,而且能够为用户提供隐私、加密和认证保护.因此,MBMS中的解密算法的研究就显得非常重要.     

The multimedia broadcast/multicast service

This article provides an overview of the multimedia broadcast/multicast service (MBMS) for universal mobile telecommunications system (UMTS) networks. We first outline the features of UMTS networks as defined by the 3rd generation partnership project (3GPP) in order to provide a background for the discussion to follow. We then present the overall MBMS architecture, the services that it provides to the users and the differences between the broadcast and multicast options. The implementation details of MBMS are explained in terms of the modifications needed to the network, the new signaling procedures required and the impact of MBMS on the radio part of the network. We then describe how the security architecture of UMTS is used to support content protection and key distribution for MBMS groups. We evaluate the prospects of MBMS by comparing it first with IP multicast and then with DVB‐H, considered by many to be the closest competitor of MBMS. Finally, we conclude with a discussion of the technical and business challenges still faced by MBMS. Copyright © 2006 John Wiley & Sons, Ltd.     

LTE架构下的多媒体资源分发方案研究

为了提高3G以及未来的移动通信系统中多媒体数据的传输率,文章提出了结合点对点(P2P)和增强型多媒体组播和广播业务(E-MBMS)技术的LTE环境下的多媒体资源分发(CPEMRD)方案。该方案结合了P2P的扩展能力和E-MBMS的可靠性、可管理性,构建了可管理的、能够承载电信级内容应用的多媒体资源分发平台。该方案缓解了终端接入数量受限以及带宽窄、通信不稳定的问题,实现了用户间点对点互动功能。     

3G时代的手机电视技术

文章对移动网络的流媒体传输技术和专用广播网手机电视的几种主要技术进行了介绍,并分析了其特点,对3G时代的手机电视发展进行了探讨。     

Efficient packet scheduling for heterogeneous multimedia provisioning over broadband satellite networks: An adaptive multidimensional QoS‐based design

With their inherent broadcast capabilities and reliable extensive geographical coverage, the broadband satellite networks are emerging as a promising approach for the delivery of multimedia services in 3G and beyond systems. Given the limited capacity of the satellite component, to meet the diverse quality of service (QoS) demands of multimedia applications, it is highly desired that the available resources can be adaptively utilized in an optimized way. In this paper, we draw our attention on the development and evaluation of an efficient packet scheduling scheme in a representative broadband satellite system, namely satellite digital multimedia broadcasting (SDMB), which is positioned as one of the most attractive solutions in the convergence of a closer integration with the terrestrial mobile networks for a cost‐effective delivery of point‐to‐multipoint services. By taking into account essential aspects of a successful QoS provisioning while preserving the system power/resource constraints, the proposed adaptive multidimensional QoS‐based (AMQ) packet scheduling scheme in this paper aims to effectively satisfy diverse QoS requirements and adaptively optimize the resource utilization for the satellite multimedia broadcasting. The proposed scheme is formulated via an adaptive service prioritization algorithm and an adaptive resource allocation algorithm. By taking into account essential performance criteria, the former is capable of prioritizing contending flows based on the QoS preferences and performance dynamics, while the latter allocates the resources, in an adaptive manner, according to the current QoS satisfaction degree of each session. Simulation results show that the AMQ scheme achieves significantly better performance than those of existing schemes on multiple performance metrics, e.g. delay, throughput, channel utilization and fairness. Copyright © 2008 John Wiley & Sons, Ltd.