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1.
Frequent content retrieval leads to significant energy consumption in cellular networks. Thereby, device-to-device (D2D) communication is used for proximal content delivery. Be aware that social friends may have common content interests, D2D content delivery is further improved by considering social network. However, how to implement efficient D2D multicast with the aid of social relationship needs further consideration. In this paper, with a proposed architecture on combined networks, the cooperation range of content sharing is investigated for D2D multicast to minimize the average energy consumption of serving a content request. Based on combined networks, a cooperation group formation scheme is proposed. Simulation results verify our analyzes and the advantage of proposed scheme. 相似文献
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在抢险救灾等应急情况下,传感器网络的节点能量更为有限。为减少无用转发的能量消耗,利用无线信道的广播特性,根据广播子树删除思想,提出一种基于最短路由树、具有最少转发节点的组播路由树生成算法。对该算法进了证明和详细分析,并针对实际需要,给出使用范围更广泛的分布式实现方法。仿真分析说明,算法的分布式实现方法可减少ODMRP的转发节点数,大大降低数据发送次数,接收成员节点较多时尤为明显。最少转发节点的组播路由树的网络总开销最小,是延长网络生存时间的有效方法。 相似文献
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针对星载IP交换机中硬件存储资源使用受限的情况,提出了一种适用于共享存储交换结构、存储资源占用少的队列管理器。通过添加索引的方法,使得所有的单播队列能够共享一个指针存储区。根据位图映射,将组播指针转化为多个单播指针,即可把组播操作的数据流按照单播操作方式写到相应的逻辑队列路径,达到节约存储器资源的目的。该队列管理器通过链表数据结构的头部和尾部来控制指针索引的写入和输出。最后,在Xilinx的xc6vlx130t FPGA进行了综合实现,结果显示,该方案相比基于指针复制的队列管理器,在8端口的交换机中存储器资源的使用量要节约22%以上。 相似文献
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提出了一种基于虚拟实时服务的协议构架,可有效发掘用户提出通信请求之前的“负时间轴”上的空闲时频资源或可再生能源,将用户可能感兴趣的内容以多播的方式预先推送到终端的存储器中,从而以非实时的通信提供虚拟实时服务,在确保服务质量的前提下大幅度提升频谱和能量效率.对终端缓存内容的选择算法进行了标准化,从而允许基站在本地预测用户已缓存的内容,并判断当前是否应发起推送和推送哪条内容;提出了虚拟实时服务涉及的若干关键算法,也给出了虚拟实时服务的演进途径及主要开放问题,旨在为相关新兴产业的技术发展提供参考. 相似文献
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Multicast transport is an efficient solution to deliver the same content simultaneously to many receivers. This transport mode is mainly used these days to deliver real-time video streams. However, multicast transmissions support over IEEE 802.11 networks does not provide any feedback policies, which implies a definite loss of missing packets. This impacts the reliability of the multicast transport and the application employing it. An alternative to improve the reliability of multicast streaming over 802.11 networks is to prevent packet losses. In this perspective, it is necessary to identify the loss causes and to perform the required prevention actions. It is well known that collisions and path loss are two fundamental sources of transmission failures. Their impact can be eliminated by means of collision prevention and data rate adaptation. However, several works show that the loss rate of multicast packets may be considerable even in collisions-free environments and using an appropriate transmission rate. Particularly they show that losses may have a bursty nature which does not correspond to the bit error rate model of the PHY layer as defined by the chipset manufacturers. Therefore, in this paper, we carry out a thorough investigation of the loss causes in wireless networks. We show that device unavailability may be the principal cause of the significant packet losses that occur and their bursty nature. Particularly, our results show that the CPU overload may incur a loss rate of 100%, and that the delivery ratio may be limited to 35% when the device is in the power save mode. 相似文献
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This paper presents a geocast technique for underwater sensor networks. The model named as Routing and Multicast Tree based Geocasting (RMTG) (TRACE'10, Bhopal, India, 2010; ICWET'10, Mumbai, India, 2010) has been designed for underwater sensor networks. In our previous work (TRACE'10, Bhopal, India, 2010; ICWET'10, Mumbai, India, 2010) we proposed only a theoretical model for underwater geocasting. The RMTG technique uses greedy forwarding and previous hop handshaking to route the packets towards the geocast region and further disseminates the data within the geocast region by creating a multicast shortest path tree. We also presented various link broken scenarios along with their solutions. The proposed model does not use the flooding technique to deliver the packets inside the geocast region that is used in most of the geocasting techniques. In this paper, we present the simulated RMTG model. The simulation results show that the proposed model provides an efficient distribution of data in the geocast region in terms of node mobility handling, packet delivery ratio and a better end‐to‐end latency. Most of the work on geocasting has been done for mobile and vehicular ad hoc networks; hence we present in this paper a novel simulated model for underwater environment. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
10.
Wireless mesh networks (WMNs) are one of key technologies for next generation wireless networks. In this paper, we propose a heuristic channel assignment algorithm with weight awareness to support mobile multicast in WMNs. To enhance network throughput, our algorithm is based on the path forwarding weight to perform channel assignment. In addition to non-overlapping channels, partially-overlapping channels are also used in channel assignment. To fully exploit all available channels in channel assignment, we devise a new channel selection metric to consider the channel separation and the distance between nodes. In mobile multicast, the multicast tree structure cannot be fixed due to receiver (multicast member) mobility. The change of the multicast tree structure will result in channel re-assignment. The proposed algorithm is based on a critical-event driven manner to reduce the times of channel re-assignment as much as possible. Finally, we perform simulation experiments to show the effectiveness of the proposed channel assignment algorithm. 相似文献