As a fundamental operation in ad hoc networks,broadcast could achieve efficient message propagations.Particularl y in the cognitive radio ad hoc network where unlicensed users have different sets of available channels...As a fundamental operation in ad hoc networks,broadcast could achieve efficient message propagations.Particularl y in the cognitive radio ad hoc network where unlicensed users have different sets of available channels,broadcasts are carried out on multiple channels.Accordingly,channel selection and collision avoidance are challenging issues to balance the efficiency against the reliability of broadcasting.In this paper,an anticollision selective broadcast protocol,called acSB,is proposed.A channel selection algorithm based on limited neighbor information is considered to maximize success rates of transmissions once the sender and receiver have the same channel.Moreover,an anticollision scheme is adopted to avoid simultaneous rebroadcasts.Consequently,the proposed broadcast acSB outperforms other approaches in terms of smaller transmission delay,higher message reach rate and fewer broadcast collisions evaluated by simulations under different scenarios.展开更多
Broadcast is an important operation in many network protocols. It is utilized to discover routes to unknown nodes in mobile ad hoc networks (MANETs) and is the key factor in scaling on-demand routing protocols to larg...Broadcast is an important operation in many network protocols. It is utilized to discover routes to unknown nodes in mobile ad hoc networks (MANETs) and is the key factor in scaling on-demand routing protocols to large networks. This paper presents the Ad Hoc Broadcast Protocol (AHBP) and its performance is discussed. In the protocol, messages are only rebroadcast by broadcast relay gateways that constitute a connected dominating set of the network. AHBP can efficiently reduce the redundant messages which make flooding-like protocols perform badly in large dense networks. Simulations are conducted to determine the performance characteristics of the protocol. The simulation results have shown excellent reduction of broadcast redundancy with AHBP. It also contributes to a reduced level of broadcast collision and congestion.展开更多
Group key exchange protocols are basic protocols to provide privacy and integrity in secure group communication. This paper discusses the security of one type of group key exchange protocols and defines the kind of pr...Group key exchange protocols are basic protocols to provide privacy and integrity in secure group communication. This paper discusses the security of one type of group key exchange protocols and defines the kind of protocols as broadcaster group protocols. It points out two attacks on this kind of protocols. The first attack can be avoided by using fresh values in each action during one session of the group protocol. The second attack should be related with concrete application. It also proposes a dynamic key agreement protocol as an example of solutions at the last part of the paper.展开更多
传统广播与新媒体的融合,提升了广播媒体的传播力和影响力,在更好地满足受众需求的同时,带来了较大的经济效益。广播融媒直播系统基于全媒体设计,搭建了内容生产、发布和融合信号汇聚的全网际互连协议(Internet Protocol,IP)技术平台,...传统广播与新媒体的融合,提升了广播媒体的传播力和影响力,在更好地满足受众需求的同时,带来了较大的经济效益。广播融媒直播系统基于全媒体设计,搭建了内容生产、发布和融合信号汇聚的全网际互连协议(Internet Protocol,IP)技术平台,依托“云+端”前后期一体化制播方案,打通了全媒体生产各流程的物理壁垒,将广播、视频直播、点播发布等各种传播形态进行深度融合,打造多元化跨界联动广播的新格局。文章主要介绍重庆广播电视集团(总台)实施的广播融媒直播及总控系统,以展示网际互联协议化音频(Audio over Internet Protocol,AoIP)和云技术在广播融媒直播系统的应用实践。展开更多
近几年,由于媒体融合的发展以及A地区广播电台的技术进步,A台原有的总控系统功能模块在逐步扩充,已经不能很好地满足广电行业今后发展需要。为了更好地整合现有信息,提高科技服务的支持水平,保证播出安全,构建覆盖广播音频、可视广播视...近几年,由于媒体融合的发展以及A地区广播电台的技术进步,A台原有的总控系统功能模块在逐步扩充,已经不能很好地满足广电行业今后发展需要。为了更好地整合现有信息,提高科技服务的支持水平,保证播出安全,构建覆盖广播音频、可视广播视频、网络流媒体接入、处理、调度、分发及监控等功能为一体的广播融媒体播控中心,是广播发展融媒化的必然要求。基于此,详细阐述了A台网际互联协议化音频(Audio over Internet Protocol,AoIP)广播电视融媒体传播控制中心的设计细节及特色。展开更多
近年来,广播电视技术转型向网际互连协议(Internet Protocol,IP)化发展的进程逐渐加快,基于IP架构的电视技术系统必将取代传统串行数字接口(Serial Digital Interface,SDI)架构,成为未来电视技术的发展方向。对以互联网协议网关(Interne...近年来,广播电视技术转型向网际互连协议(Internet Protocol,IP)化发展的进程逐渐加快,基于IP架构的电视技术系统必将取代传统串行数字接口(Serial Digital Interface,SDI)架构,成为未来电视技术的发展方向。对以互联网协议网关(Internet Protocol Gateway,IPG)作为关键设备搭建“SDI+IP”混合架构系统的设计方案进行深入分析,阐述电视技术系统从SDI向IP技术转型过程中尽可能实现平稳过渡的思路。展开更多
网际互连协议(Internet Protocol,IP)化网络作为一种新兴的传输技术,正在改变传统的电视制作和播出模式。基于此,概述了IP化技术的相关概念,分析了IP化技术的数字编码和分组传输机制,阐述了IP化技术在推动电视制播融合方面的作用,提出...网际互连协议(Internet Protocol,IP)化网络作为一种新兴的传输技术,正在改变传统的电视制作和播出模式。基于此,概述了IP化技术的相关概念,分析了IP化技术的数字编码和分组传输机制,阐述了IP化技术在推动电视制播融合方面的作用,提出了电视制播IP化网络的分层架构,解析了IP化核心网和接入网的组成,以及软件定义网络(Software Defined Network,SDN)在IP化网络中的控制作用。展开更多
Problems of the current IGMP mechanism were identified, such as unnecessary periodic probing of hosts and leave latency, which wastes bandwidth and cause more traffic and overhead. Alternative mechanism that preserve ...Problems of the current IGMP mechanism were identified, such as unnecessary periodic probing of hosts and leave latency, which wastes bandwidth and cause more traffic and overhead. Alternative mechanism that preserve the IP multicast model but employ join/leave messages to track local group membership for broadcast LANs (shared medium LANs) was proposed in this paper. We describe the implementation requirements of the new mechanism and compare it to existing one, demonstrating that join/leave approach is uniformly superior for the environment of broadcast LANs.展开更多
The rapid development of Internet has led to the explosion of information sharing, and how to supervise the sharing is a main research topic on current Internet. Aiming at the disadvantage that the current Peer-to-Pee...The rapid development of Internet has led to the explosion of information sharing, and how to supervise the sharing is a main research topic on current Internet. Aiming at the disadvantage that the current Peer-to-Peer (P2P) is hard to manage and control, this paper presents a Session Initial Protocol (SIP)-based P2P network of three-level architecture. SIP middleware is introduced to the middle level of the three-layer architecture. By the connection function of the SIP signaling, the P2P transmission on media-level can be controlled. Using SIP’s register and authentication function, the manage layer can manage the whole P2P network. Based on the aforementioned architecture, this paper investigates the grouping strategy on a live broadcast application in P2P network. Combined with the function of SIP register, the paper works on several grouping strategies, sets up models to manage users by grouping them, presents a weight-based K-means IP address grouping algorithm, and realizes it. The experiment shows that the grouping strategy presented in this paper can solve the problem of group sharing of network resource, and can realize the efficient-sharing, reasonable-distributing of network resource.展开更多
文章主要讨论了移动互联网时代背景下,赛事直播在电竞和体育领域中采用的不同传输协议及其适用性。具体比较了网页实时通信(Web Real-Time Communications,WebRTC)、超文本直播流(Hyper Text Transfer Protocol Live Streaming,HLS)、...文章主要讨论了移动互联网时代背景下,赛事直播在电竞和体育领域中采用的不同传输协议及其适用性。具体比较了网页实时通信(Web Real-Time Communications,WebRTC)、超文本直播流(Hyper Text Transfer Protocol Live Streaming,HLS)、低延迟超文本直播流(Low Latency Hyper Text Transfer Protocol Live Streaming,LL-HLS)、基于超文本传输协议的Flash视频协议(HyperText Transfer Protocol Flash Video,HTTP-FLV)、基于HTTP的动态自适应流媒体传输协议(Dynamic Adaptive Streaming over HTTP,DASH)和低延迟基于超文本传输协议的动态自适应流媒体传输协议(Low Latency Dynamic Adaptive Streaming over HyperText Transfer Protocol,LL-DASH)传输协议,分析了这些协议在电竞体育赛事场景下的延迟和终端支持情况,并结合实际例子探讨传输架构及其影响。研究结果表明,不同的传输协议有各自的优缺点,可在不同场景下应用。而对于常规赛转播,传输架构也是决定延迟的重要因素,分布式传输架构能够更好地实现低延迟和稳定性。因此,文章对于选择合适的传输协议和传输架构具有一定的借鉴意义。展开更多
文摘As a fundamental operation in ad hoc networks,broadcast could achieve efficient message propagations.Particularl y in the cognitive radio ad hoc network where unlicensed users have different sets of available channels,broadcasts are carried out on multiple channels.Accordingly,channel selection and collision avoidance are challenging issues to balance the efficiency against the reliability of broadcasting.In this paper,an anticollision selective broadcast protocol,called acSB,is proposed.A channel selection algorithm based on limited neighbor information is considered to maximize success rates of transmissions once the sender and receiver have the same channel.Moreover,an anticollision scheme is adopted to avoid simultaneous rebroadcasts.Consequently,the proposed broadcast acSB outperforms other approaches in terms of smaller transmission delay,higher message reach rate and fewer broadcast collisions evaluated by simulations under different scenarios.
基金the National '863' High-Tech Programme of China (No. 863- 300- 01-03-99 ).
文摘Broadcast is an important operation in many network protocols. It is utilized to discover routes to unknown nodes in mobile ad hoc networks (MANETs) and is the key factor in scaling on-demand routing protocols to large networks. This paper presents the Ad Hoc Broadcast Protocol (AHBP) and its performance is discussed. In the protocol, messages are only rebroadcast by broadcast relay gateways that constitute a connected dominating set of the network. AHBP can efficiently reduce the redundant messages which make flooding-like protocols perform badly in large dense networks. Simulations are conducted to determine the performance characteristics of the protocol. The simulation results have shown excellent reduction of broadcast redundancy with AHBP. It also contributes to a reduced level of broadcast collision and congestion.
基金Supported by the National Natural Science Foun-dation of China (90104005 ,60473023) the National High Tech-nology Research and Development Programof China (863 Program)(2002AA41051)
文摘Group key exchange protocols are basic protocols to provide privacy and integrity in secure group communication. This paper discusses the security of one type of group key exchange protocols and defines the kind of protocols as broadcaster group protocols. It points out two attacks on this kind of protocols. The first attack can be avoided by using fresh values in each action during one session of the group protocol. The second attack should be related with concrete application. It also proposes a dynamic key agreement protocol as an example of solutions at the last part of the paper.
文摘传统广播与新媒体的融合,提升了广播媒体的传播力和影响力,在更好地满足受众需求的同时,带来了较大的经济效益。广播融媒直播系统基于全媒体设计,搭建了内容生产、发布和融合信号汇聚的全网际互连协议(Internet Protocol,IP)技术平台,依托“云+端”前后期一体化制播方案,打通了全媒体生产各流程的物理壁垒,将广播、视频直播、点播发布等各种传播形态进行深度融合,打造多元化跨界联动广播的新格局。文章主要介绍重庆广播电视集团(总台)实施的广播融媒直播及总控系统,以展示网际互联协议化音频(Audio over Internet Protocol,AoIP)和云技术在广播融媒直播系统的应用实践。
文摘近几年,由于媒体融合的发展以及A地区广播电台的技术进步,A台原有的总控系统功能模块在逐步扩充,已经不能很好地满足广电行业今后发展需要。为了更好地整合现有信息,提高科技服务的支持水平,保证播出安全,构建覆盖广播音频、可视广播视频、网络流媒体接入、处理、调度、分发及监控等功能为一体的广播融媒体播控中心,是广播发展融媒化的必然要求。基于此,详细阐述了A台网际互联协议化音频(Audio over Internet Protocol,AoIP)广播电视融媒体传播控制中心的设计细节及特色。
文摘网际互连协议(Internet Protocol,IP)化网络作为一种新兴的传输技术,正在改变传统的电视制作和播出模式。基于此,概述了IP化技术的相关概念,分析了IP化技术的数字编码和分组传输机制,阐述了IP化技术在推动电视制播融合方面的作用,提出了电视制播IP化网络的分层架构,解析了IP化核心网和接入网的组成,以及软件定义网络(Software Defined Network,SDN)在IP化网络中的控制作用。
文摘Problems of the current IGMP mechanism were identified, such as unnecessary periodic probing of hosts and leave latency, which wastes bandwidth and cause more traffic and overhead. Alternative mechanism that preserve the IP multicast model but employ join/leave messages to track local group membership for broadcast LANs (shared medium LANs) was proposed in this paper. We describe the implementation requirements of the new mechanism and compare it to existing one, demonstrating that join/leave approach is uniformly superior for the environment of broadcast LANs.
基金Supported in part by the Hi-Tech R&D Program (863) of China (2006AA01Z444)the CNGI 2006 Application Demonstration Program (The IPv6 Distributed Multi-media Communication System Based On SIP and WISI/WIMAX )Tsinghua-Microsoft Key Laboratory Fund Project
文摘The rapid development of Internet has led to the explosion of information sharing, and how to supervise the sharing is a main research topic on current Internet. Aiming at the disadvantage that the current Peer-to-Peer (P2P) is hard to manage and control, this paper presents a Session Initial Protocol (SIP)-based P2P network of three-level architecture. SIP middleware is introduced to the middle level of the three-layer architecture. By the connection function of the SIP signaling, the P2P transmission on media-level can be controlled. Using SIP’s register and authentication function, the manage layer can manage the whole P2P network. Based on the aforementioned architecture, this paper investigates the grouping strategy on a live broadcast application in P2P network. Combined with the function of SIP register, the paper works on several grouping strategies, sets up models to manage users by grouping them, presents a weight-based K-means IP address grouping algorithm, and realizes it. The experiment shows that the grouping strategy presented in this paper can solve the problem of group sharing of network resource, and can realize the efficient-sharing, reasonable-distributing of network resource.
文摘文章主要讨论了移动互联网时代背景下,赛事直播在电竞和体育领域中采用的不同传输协议及其适用性。具体比较了网页实时通信(Web Real-Time Communications,WebRTC)、超文本直播流(Hyper Text Transfer Protocol Live Streaming,HLS)、低延迟超文本直播流(Low Latency Hyper Text Transfer Protocol Live Streaming,LL-HLS)、基于超文本传输协议的Flash视频协议(HyperText Transfer Protocol Flash Video,HTTP-FLV)、基于HTTP的动态自适应流媒体传输协议(Dynamic Adaptive Streaming over HTTP,DASH)和低延迟基于超文本传输协议的动态自适应流媒体传输协议(Low Latency Dynamic Adaptive Streaming over HyperText Transfer Protocol,LL-DASH)传输协议,分析了这些协议在电竞体育赛事场景下的延迟和终端支持情况,并结合实际例子探讨传输架构及其影响。研究结果表明,不同的传输协议有各自的优缺点,可在不同场景下应用。而对于常规赛转播,传输架构也是决定延迟的重要因素,分布式传输架构能够更好地实现低延迟和稳定性。因此,文章对于选择合适的传输协议和传输架构具有一定的借鉴意义。
