Beginning with the simple introduction of socket which is the most commonly used application program interfaces in UNIX/LINUX communication domain, the concrete programming procedures to realize multicast and broadcas...Beginning with the simple introduction of socket which is the most commonly used application program interfaces in UNIX/LINUX communication domain, the concrete programming procedures to realize multicast and broadcast based on socket is provided, according to TCP/IP protocol in LINUX system. The acquiring and converting of broadcast destination address and multicast address, the setting of multicast options, the joining in and withdrawing from the multicast group, and the receiving and sending of datagram are all demonstrated in it, the related system calls and simple explication of C programming are also included.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 cdma2000 1xEV-DO mobile communication system provides broadcast and multicast services(BCMCS) to meet an increasing demand for multimedia data services.Single frequency network(SFN) is recognized as an effective w...The cdma2000 1xEV-DO mobile communication system provides broadcast and multicast services(BCMCS) to meet an increasing demand for multimedia data services.Single frequency network(SFN) is recognized as an effective way to improve the spectral efficiency of the BCMCS system.To improve the coverage and the data rate of the BCMCS users,an interference cancellation algorithm based on macro diversity is introduced in this paper.The performance of BCMCS in CDMA2000 EV-DO networks under the condition of SFN is evaluated.The simulation results show a significant improvement in bit error ratio(BER) while quantitatively validating the efficiency of our approach.展开更多
为了提高网络路由性能,提出并设计了一种基于遗传-蚁群优化算法的服务质量(quality of service,QoS)组播路由算法。首先,设计了自适应变频采集策略用于采集网络与节点信息,以此获得网络和节点的状态,为后续路由优化提供数据支持;其次,...为了提高网络路由性能,提出并设计了一种基于遗传-蚁群优化算法的服务质量(quality of service,QoS)组播路由算法。首先,设计了自适应变频采集策略用于采集网络与节点信息,以此获得网络和节点的状态,为后续路由优化提供数据支持;其次,计算路径代价,将路径代价最小作为优化目标,建立QoS组播路由优化模型,并设置相关约束条件;最后,结合遗传算法和蚁群算法提出一种遗传-蚁群优化算法求解上述模型,输出最优路径,完成路由优化。实验结果表明,所提算法可有效降低路径长度与路径代价,提高搜索效率与路由请求成功率,优化后的路由时延抖动较小。展开更多
介绍我国应急广播发展现状,包括政策层面提供的支持、系统建设和平台对接有序推进、传播路径和应用场景的广泛拓展以及实现“人断我通”这一核心发展策略的进展。深入剖析5G新无线(New Radio,NR)广播、世界数字广播(Digital Radio Mondi...介绍我国应急广播发展现状,包括政策层面提供的支持、系统建设和平台对接有序推进、传播路径和应用场景的广泛拓展以及实现“人断我通”这一核心发展策略的进展。深入剖析5G新无线(New Radio,NR)广播、世界数字广播(Digital Radio Mondiale,DRM)、北斗卫星导航系统等技术的应用优势,并通过具体的应用实例进行说明,旨在为新技术在应急广播领域的创新应用提供参考。展开更多
Multicasting is a communication service that allows an application to efficiently transmit copies of data packets to a set of destination nodes. The problem of finding a minimum cost multicast tree can be formulated a...Multicasting is a communication service that allows an application to efficiently transmit copies of data packets to a set of destination nodes. The problem of finding a minimum cost multicast tree can be formulated as a minimum Steiner tree problem in networks, which is NP-completeness. MPH (minimum path cost heuristic) algorithm is a famous solution to this problem. In this paper, we present a novel solution TPMPH (two phase minimum path cost heuristic) to improve the MPH by generating the nodes and the edges of multicast tree separately. The cost of multicast tree generated by the proposed algorithm with the same time as MPH is no more than that of MPH in the worst case. Extensive simulation results show that TPMPH can effectively improve the performance on MPH, and performs better in large-scale networks and wireless networks.展开更多
The multimedia broadcast and multicast services (MBMS) in 3GPP LTE is characterized by multicast broadcast single frequency network (MBSFN) operation. The multicast services are transmitted by single frequency network...The multimedia broadcast and multicast services (MBMS) in 3GPP LTE is characterized by multicast broadcast single frequency network (MBSFN) operation. The multicast services are transmitted by single frequency network (SFN) mode, and the unicast services are delivered with point-to-point (PTP) mode. To minimize the demanded radio resources for multicast services in the LTE, a novel mode switch (MS) between SFN and PTP for multicast services is proposed. MS takes into account PTP mode for multicast services and the switch is based on the handover threshold. To solve the minimization problem, MS adapts the handover threshold with the difference in the demanded radio resources between SFN mode and PTP mode for multicast services. The simulation results show that the proposed MS achieves less demanded radio resources than SFN mode for all the multicast services.展开更多
Mobile multicast is important for the emerging applications such as mobile video or audio conference and mobile IPTV.Some mobile multicast schemes have been proposed in the past few years, but most of them study the r...Mobile multicast is important for the emerging applications such as mobile video or audio conference and mobile IPTV.Some mobile multicast schemes have been proposed in the past few years, but most of them study the reconstruc-tion of multicast delivery tree, and few consider the group membership management for mobile sub-scribers.In this paper, we propose a new mobile multicast method based on the Two-Hop Multicast Listener Discovery(THMLD) protocol which pro-vides the mobile multicast membership manage-ment function by forwarding the traditional MLD messages to its neighboring subnets.To evaluate its performance, we analyze the THMLD and set up the simulation platform to compare it with the several traditional mobile multicast methods.The results show that THMLD can reduce the multicast join time, and the THMLD-based mobile multicast method can reduce the multicast join delay at a cost of increasing additional multicast maintenance cost.展开更多
随着光纤网络技术的不断发展,广播电视全网际协议(Internet Protocol,IP)化的光纤入户(Fiber to the Home,FTTH)工作也逐步开展,将进一步提升用户获取信息资源的质量和效率。目前,FTTH光纤网络建设的主流技术路线包括超万兆光纤入户技术...随着光纤网络技术的不断发展,广播电视全网际协议(Internet Protocol,IP)化的光纤入户(Fiber to the Home,FTTH)工作也逐步开展,将进一步提升用户获取信息资源的质量和效率。目前,FTTH光纤网络建设的主流技术路线包括超万兆光纤入户技术(All IP over PON,I-PON)和吉比特无源光网络(Gigabit-Capable Passive Optical Network,GPON)技术。从两者的网络架构、系统性能、技术实现以及成本控制等方面进行差异化分析,并针对性给出FTTH部署的意见和建议,以期为相关网络设计与建设指明方向。展开更多
文摘Beginning with the simple introduction of socket which is the most commonly used application program interfaces in UNIX/LINUX communication domain, the concrete programming procedures to realize multicast and broadcast based on socket is provided, according to TCP/IP protocol in LINUX system. The acquiring and converting of broadcast destination address and multicast address, the setting of multicast options, the joining in and withdrawing from the multicast group, and the receiving and sending of datagram are all demonstrated in it, the related system calls and simple explication of C programming are also included.
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.
文摘The cdma2000 1xEV-DO mobile communication system provides broadcast and multicast services(BCMCS) to meet an increasing demand for multimedia data services.Single frequency network(SFN) is recognized as an effective way to improve the spectral efficiency of the BCMCS system.To improve the coverage and the data rate of the BCMCS users,an interference cancellation algorithm based on macro diversity is introduced in this paper.The performance of BCMCS in CDMA2000 EV-DO networks under the condition of SFN is evaluated.The simulation results show a significant improvement in bit error ratio(BER) while quantitatively validating the efficiency of our approach.
文摘为了提高网络路由性能,提出并设计了一种基于遗传-蚁群优化算法的服务质量(quality of service,QoS)组播路由算法。首先,设计了自适应变频采集策略用于采集网络与节点信息,以此获得网络和节点的状态,为后续路由优化提供数据支持;其次,计算路径代价,将路径代价最小作为优化目标,建立QoS组播路由优化模型,并设置相关约束条件;最后,结合遗传算法和蚁群算法提出一种遗传-蚁群优化算法求解上述模型,输出最优路径,完成路由优化。实验结果表明,所提算法可有效降低路径长度与路径代价,提高搜索效率与路由请求成功率,优化后的路由时延抖动较小。
文摘介绍我国应急广播发展现状,包括政策层面提供的支持、系统建设和平台对接有序推进、传播路径和应用场景的广泛拓展以及实现“人断我通”这一核心发展策略的进展。深入剖析5G新无线(New Radio,NR)广播、世界数字广播(Digital Radio Mondiale,DRM)、北斗卫星导航系统等技术的应用优势,并通过具体的应用实例进行说明,旨在为新技术在应急广播领域的创新应用提供参考。
文摘Multicasting is a communication service that allows an application to efficiently transmit copies of data packets to a set of destination nodes. The problem of finding a minimum cost multicast tree can be formulated as a minimum Steiner tree problem in networks, which is NP-completeness. MPH (minimum path cost heuristic) algorithm is a famous solution to this problem. In this paper, we present a novel solution TPMPH (two phase minimum path cost heuristic) to improve the MPH by generating the nodes and the edges of multicast tree separately. The cost of multicast tree generated by the proposed algorithm with the same time as MPH is no more than that of MPH in the worst case. Extensive simulation results show that TPMPH can effectively improve the performance on MPH, and performs better in large-scale networks and wireless networks.
基金Sponsored by the National Key Technology R&D Program of China ( Grant No. 2010ZX03003-001-01)Fundamental Research Funds for the Central Universities
文摘The multimedia broadcast and multicast services (MBMS) in 3GPP LTE is characterized by multicast broadcast single frequency network (MBSFN) operation. The multicast services are transmitted by single frequency network (SFN) mode, and the unicast services are delivered with point-to-point (PTP) mode. To minimize the demanded radio resources for multicast services in the LTE, a novel mode switch (MS) between SFN and PTP for multicast services is proposed. MS takes into account PTP mode for multicast services and the switch is based on the handover threshold. To solve the minimization problem, MS adapts the handover threshold with the difference in the demanded radio resources between SFN mode and PTP mode for multicast services. The simulation results show that the proposed MS achieves less demanded radio resources than SFN mode for all the multicast services.
基金supported in part by 973 program under con-tract 2007CB307101National High Technology of China ("863 program") under contract No. 2008AA01A326 National Natural Science Foundation of China under Grant No. 60870015 and No. 60833002
文摘Mobile multicast is important for the emerging applications such as mobile video or audio conference and mobile IPTV.Some mobile multicast schemes have been proposed in the past few years, but most of them study the reconstruc-tion of multicast delivery tree, and few consider the group membership management for mobile sub-scribers.In this paper, we propose a new mobile multicast method based on the Two-Hop Multicast Listener Discovery(THMLD) protocol which pro-vides the mobile multicast membership manage-ment function by forwarding the traditional MLD messages to its neighboring subnets.To evaluate its performance, we analyze the THMLD and set up the simulation platform to compare it with the several traditional mobile multicast methods.The results show that THMLD can reduce the multicast join time, and the THMLD-based mobile multicast method can reduce the multicast join delay at a cost of increasing additional multicast maintenance cost.
文摘随着光纤网络技术的不断发展,广播电视全网际协议(Internet Protocol,IP)化的光纤入户(Fiber to the Home,FTTH)工作也逐步开展,将进一步提升用户获取信息资源的质量和效率。目前,FTTH光纤网络建设的主流技术路线包括超万兆光纤入户技术(All IP over PON,I-PON)和吉比特无源光网络(Gigabit-Capable Passive Optical Network,GPON)技术。从两者的网络架构、系统性能、技术实现以及成本控制等方面进行差异化分析,并针对性给出FTTH部署的意见和建议,以期为相关网络设计与建设指明方向。
