CCN中基于业务类型的多样化内容分发机制

针对内容中心网络(Content Centric Networking,CCN)如何提供差异化的业务需求服务的问题,采用区分服务的思想,从内容传输和缓存决策的角度出发,提出了一种基于业务类型的多样化内容分发机制.该机制依据不同的业务请求特征,分别设计了持久推送、并行预测和逐包请求的数据分发模式,对应提出了透明转发、边缘概率缓存和渐进式推进的沿途存储策略,实现了内容传递对于业务类型的感知和匹配.仿真结果表明,该机制减小了内容请求时延,提高了缓存命中率,以少量额外的控制开销提升了CCN网络整体的内容分发性能.     

面向ICN切片的视频缓存与传输服务

随着视频流量爆炸式地增长,为了降低密集区域用户的视频检索时延和网络负载,利用网络功能虚拟化技术提出了一种将5G切片与信息中心网络(Information Center Network,ICN)相结合的内容分发服务系统集成的架构,并改进基于ICN的缓存策略.该缓存策略依据特定区域用户一个月与一周内的历史访问记录构建视频主...     

基于可重构路由器上缓存的流媒体协作分发策略

提出一种新颖的基于可重构路由器上缓存的协作分发策略来加速流媒体。通过网络存储即多个边缘路由器节点对热点视频数据进行合作缓存,就近为用户提供服务,从而使得流媒体服务器的性能要求尤其是带宽需求得到巨大的降低,骨干网传输的流量也明显减少,同时用户响应延迟也得到明显的改善。此外,实现了一个原型系统来评价基于路由器上缓存的流媒体协作分发策略的性能,结果表明该方案相比于现有的方案在改善网络性能以及用户体验方面取得很大的提升。     

基于边缘计算的高效视频内容分发关键技术与挑战

近年来移动互联网、工业互联网的快速发展,引发媒体计算与服务的一个新的趋势:以视频为代表的多媒体数据的产生、处理和分发越来越多地趋向网络边缘。复杂应用环境下,用户行为、系统资源的不确定性成为网络视频服务面临的重大挑战。如何引入人工智能与机器学习的方法,利用网络边缘的计算、存储和网络资源实现视频内容分发随需而动,从而支撑更低延迟、更高带宽需求的网络视频服务,逐渐成为新的研究和应用热点。该综述分析了基于边缘计算的视频分发所面临的挑战,提出了通过边缘计算的网络、存储和计算能力来进行视频内容分发的框架,并在此框架下给出了边缘缓存及替换、边缘内容预取、边缘内容收集和边缘计算迁移等视频分发的优化策略设计。     

移动边缘计算中基于联邦学习的视频请求预测和协作缓存策略

随着互联网社交平台的崛起和移动智能终端设备的普及,自媒体短视频、直播等视频业务蓬勃发展,人们对高质量视频服务的需求也急剧上升。与此同时,连接到核心网络的大量智能设备增加了回程链路的负载,传统的云计算难以满足用户对视频服务的低延迟要求。移动边缘计算(MEC)通过在网络边缘部署具有计算和存储能力的边缘节点,通过在更靠近用户的边缘侧提高计算和存储服务,降低了数据传输时延进而缓解了网络阻塞。因此,基于MEC架构,该文充分利用网络边缘资源,提出了基于联邦学习的视频请求预测和视频协作缓存策略。通过利用多个边缘节点对提出的深度请求预测模型(DRPN)视频请求预测模型进行联邦训练,预测视频未来的请求情况,然后量化缓存内容所带来的时延收益并协作地以最大化该时延收益为目的进行缓存决策。该文分析了真实数据集MovieLens,模拟了视频请求缓存场景并进行实验。仿真结果表明,相比于其他策略,所提策略不仅能有效降低用户等待时延,在有限的缓存空间中提高内容多样性,从而提高缓存命中率,降低缓存成本,还能降低整个系统的通信成本。     

用户行为感知与网络边缘内容分发优化策略研究

本文针对移动端视频服务特性,设计了基于用户内容偏好和移动行为感知的网络边缘节点内容分发优化策略,该优化策略能够快速响应移动端用户兴趣,大大减少主干网络带宽资源的消耗,同时提升了用户的收视体验,有利于广电网络运营商优化网络配置并提升服务质量。     

带有特征感知的D2D内容缓存策略

设备到设备通信(D2D)可以有效地卸载基站流量,在D2D网络中不仅需要共享大众化内容还需要个性化内容缓存。该文对缓存内容选择问题进行了深入研究,提出一种结合特征感知的内容社交价值预测(CSVP)方法。价值预测不仅可以降低时延也可以减少缓存替换次数降低缓存成本。首先结合用户特征和内容特征计算内容当前价值,然后通过用户社交关系计算未来价值。微基站根据内容的价值为用户提供个性化内容缓存服务,宏基站则在每个微基站的缓存内容中选择价值较大部分的内容。仿真结果表明,该文提出的缓存策略可以有效缓解基站流量,与其他方法相比降低时延约20%～40%。     

基于停放车辆路边单元环境感知的车联网资源高效分配

为减少路边单元（RSU）部署,同时满足移动车辆用户对处理时延敏感和计算密集任务的需求,提出了基于停放车辆环境感知的资源分配算法。选择路边停放的车辆替代RSU为车辆用户提供服务,将停放时间作为选择停放车辆路边单元（PCRSU）的决策要素,分别在内容缓存和分发2个方面设计了减小需求响应时延的机制。在内容缓存方面,PCRSU通过感知用户历史搜索数据与兴趣点区域类型两类要素对用户进行个性化的内容推荐。在内容分发方面,PCRSU通过感知车辆用户的数据传输需求,对带宽进行高效分配。实验证明,与已有方法相比,所提算法能更合理地选择PCRSU,有效降低系统的需求响应时延,在保证网络覆盖的同时提升系统稳定性,并且能为车辆用户提供更加准确的服务内容。     

一种适合城市交通的VANET组网方法研究

车载自组网(VANET)具有规模大、节点分布不均且移动性强等特点,VANET的组网技术已经成为该领域的研究热点.针对城市交通环境,提出了一种基于分簇结构的VANET组网方法,以公交车为簇头,重点研究了簇头的动态选举、簇内成员的动态管理等问题.在网络的连通性方面,提出了利用路边停靠车辆缓存转发的策略.通过仿真实验,对方案进行了分析验证,结果表明,该方案可有效延长通信时间,提高传输效率.     

基于内容流行度和节点中心度匹配的信息中心网络缓存策略

在信息中心网络(Information-Centric Network, ICN)中,利用网络内置缓存提高内容获取及传输效率是该网络构架最重要的特性。然而,网络内置的缓存存在应对大量的需要转发的内容时能力相对弱小,对内容放置缺乏均衡分布的问题。该文提出基于内容流行度和节点中心度匹配的缓存策略(Popularity and Centrality Based Caching Scheme, PCBCS),通过对经过的内容进行选择性缓存来提高内容分发沿路节点的缓存空间使用效率,减少缓存冗余。仿真结果表明,该文提出的算法和全局沿路缓存决策方案,LCD(Leave Copy Down)以及参数为0.7及0.3的Prob(copy with Probability)相比较,在服务器命中率上平均减少30%,在命中缓存内容所需的跳数上平均减少20%,最重要的是,和全局沿路缓存决策方案相比总体缓存替换数量平均减少了40%。     

Link efficiency and quality of experience aware routing protocol to improve video streaming in urban VANETs

In a vehicular ad‐hoc network (VANET), vehicles can play an essential role in monitoring areas of a smart city by transmitting data or multimedia content of environmental circumstances like disasters or road conditions. Multimedia content communication with quality of experience (QoE) guarantees is a challenging undertaking in an environment such as that of a VANET. Indeed, a VANET is characterized by numerous varying conditions, significantly impacting its topology, quality of communication channels, and paths with respect to bandwidth, loss, and delay. This paper introduces a link efficiency and quality of experience aware routing protocol (LEQRV) to improve video streaming provisioning in urban vehicular ad‐hoc networks. LEQRV uses an enhanced greedy forwarding‐based approach to create and maintain stable high quality routes for video streaming delivery. It improves the performance of the quality of experience by increasing the achieved QoE scores and reducing the forwarding end‐to‐end delay and frame loss.     

用于VANET紧急消息传输的改进二元分割广播协议

摘要：针对车辆自组织网络（vehicular Ad Hoc network,VANET）中紧急消息的传输,提出一个改进的二元分割广播（MBPAB）协议。协议将通信范围迭代划分成小的区域,寻找离发送节点最远区域内的车辆,对紧急消息执行转发,通过减少转发跳数,提高消息传播速度。通过引入MAC（medium access control）子层的微型分布式帧间间隔（mini-DIFS）,赋予对紧急消息以更高的优先级接入通信信道。仿真结果表明,在VANET 中, MBPAB协议与现有的广播协议相比,在通信时延和消息传播速度方面有更好的性能表现。     

Multipath inter-domain routing for named data networking

To facilitate content retrieval among NDN domains,a multipath inter-domain routing for named data networking(MIRNDN)was proposed.Under MIRNDN,an AS(autonomous system)maintained merely the routing state of content reachable from its own network or from its customers’ networks and aggregated routing information to mitigate routing scalability issue; “valley free”routing policy was applied to guide Interest packets that solicit content unreachable from the AS’s own network nor from its customers’ networks to explore matching data packets via multiple paths,and NDN’s requests aggregation,in-network caching and adaptive forwarding optimized such exploration; the reachability information of content from multiple paths was collected to support Interest multipath forwarding.The properties of FIB size and the convergence time and communication cost of routing update under MIRNDN were analyzed in theory.The experimental results in the AS level topology of current Internet validates that MIRNDN mitigates the scalability issue of NDN inter-domain routing,has relative short convergence time and moderate communication cost for routing update,and effectively reduces unnecessary Interest forwarding.     

Will video caching remain energy efficient in future core optical networks?

Optical networks are expected to cater for the future Internet due to the high speed and capacity that they offer. Caching in the core network has proven to reduce power usage for various video services in current optical networks. This paper investigates whether video caching will still remain power efficient in future optical networks. The study compares the power consumption of caching in a current IP over WDM core network to a future network. The study considers a number of features to exemplify future networks. Future optical networks are considered where: (1) network devices consume less power, (2) network devices have sleep-mode capabilities, (3) IP over WDM implements lightpath bypass, and (4) the demand for video content significantly increases and high definition video dominates. Results show that video caching in future optical networks saves up to 42% of power consumption even when the power consumption of transport reduces. These results suggest that video caching is expected to remain a green option in video services in the future Internet.     

A Broadband High Gain Tapered Slot Antenna for Underwater Communication in Microwave Band

Named Data Networking (NDN), an emerging communication model in the content centric networks, has recently presented a solid framework for the future Internet. The NDN exploits content name instead of host name (IP address) and content caching. These features make NDN particularly efficient in networks with intermittent connectivity and dynamic topologies such as mobile ad hoc networks (MANETs). Due to the structure of NDN nodes, design of forwarding strategies has a vital impact on the network performance. In this paper, we propose a new forwarding strategy: redundancy elimination forwarding (REF). In REF, the NDN node structure and the operation of the data structures are modified. These modifications improve network performance in terms of throughput, overhead and resource requirements. REF strategy is simulated in different scenarios based on ndnSIM and the results demonstrate that it provides robust performance for various environments.

     

关于Cache在移动互联网的应用与分析

Cache是一种互联网高速缓存系统,是目前移动运营商提升数据业务下载速率最有效的手段之一。它通过分析和研究互联网业务的请求链接URL,采用被动缓存技术,对热点业务的资源内容进行缓存和重定向转发,将外网资源迁移至网内进行本地化缓存,达到缩短终端用户下载目标资源的路径长度的目的。对P2P文件传输、HTTP文件下载、Web页面浏览以及在线视频播放等各种应用实现网内缓存加速,能提升30%左右的下载速率。同时Cache系统中的重定向功能,也可对移动数据业务访问成功率带来2.2%的提升。     

Hybrid 802.11p-cellular architecture for NDN-based VANET

Vehicular network communications (VANET) face multiple challenges due to their intermittent connections and the rapid changes in their topologies. In recent years, several research efforts have explored the use of content-centric approaches to alleviate some of these challenges. One of these promising network designs is Named Data Networking (NDN), which has become a valid solution to support VANET applications. However, in the NDN architecture, the main forwarding mechanism for the interest packets is flooding. This forwarding mechanism will result in excessive collisions, which will lead to the broadcast storm problem. In this paper, we propose VC-NDN: a hybrid and hierarchical Named Data Networking architecture for VANETs. VC-NDN improves content retrieval efficiency through an adapted NDN-based communication model. VC-NDN includes a new interest forwarding scheme to reduce packet collision in the network and an efficient mechanism to support push-based traffic. Furthermore, to reduce communication costs, VC-NDN uses two communication technologies in parallel, namely, IEEE 802.11p and cellular communications, while keeping the usage of the cellular network at a minimum level. Finally, to reduce the impact on vehicle mobility, VC-NDN follows a hierarchical clustering architecture. Specifically, a density-based clustering algorithm is designed to create and maintain stable clusters with multihop communication capability. Our performance study shows that VC-NDN outperforms the basic VNDN solutions in terms of data retrieval delay and packet delivery ratio while minimizing the usage of the cellular network.     

CCN基于内容的缓存策略

内容中心网络（Content Centric Networking,CCN）以内容为中心进行数据通讯,改变了当前互联网host-host通讯模型,并且具有网内缓存功能。为了解决网内数据协同缓存的难题,借鉴通讯模式的改革,建议以内容为中心缓存数据,提出以内容和缓存为中心的网络（Content＆Caching Centric Networking,CCCN）概念。经过大量理论分析和仿真实验,结果表明,在数据缓存和内容转发上CCCN是非常高效和可行的。     

应用于协议无感知转发交换机的流缓存方法

协议无感知转发支持任意协议的解析和处理,增强了软件定义网络的可编程能力。为提高转发性能,该文提出一种应用于协议无感知转发交换机的流缓存方法,通过识别匹配和动作的依赖关系,得到匹配字段的绝对位置,用以预先解析报文。为确保流缓存的加速效果,根据匹配类型与表项数量选择应用流缓存的流表。此外,该文对比了单流表缓存与多流表缓存对转发性能的提升,并提出了根据网络流量实际情况的自适应切换策略。通过扩展POFSwitch实现所提方法,并用实际规则与骨干网流量进行验证,应用流缓存后,交换机报文转发速率提升了220%。流缓存可以为可编程数据平面提供更高的转发性能。