Reliable transmission mechanism with differentiated protection in virtualized fiber-wireless access network

In view of the different reliability requirements of network service,a reliable transmission mechanism with differentiated protection was proposed in virtualized fiber-wireless access network.The quality of protection required by users and the fees that can be paid were used as a prerequisite.The backup protection resources were flexibly allocated by quantifying the multi-level protection quality with the probability of recovery.Then,for reducing traffic congestion and the unprotected services,the level service differentiation algorithm was used to choose protection link which was satisfied with the level of protection quality.The results show the proposed mechanism has more advantages in terms of long-term benefit-to-cost ratio and underlying network resource overhead,and provides users with a more flexible virtual network transmission while satisfying users’ reliability requirements.     

车用自组网媒体访问控制机制改进

为提升车用自组网传输音频、视频的服务质量,对基于IEEE802.11p的车用无线接入技术MAC机制进行改进,提出竞争窗口自适应EDCA机制。仿真实验表明,竞争窗口自适应EDCA机制有效地降低了车用自组网中音频、视频流的传输时延、时延抖动和丢包率,保证了车用自组网传输VoIP、视频会议、音视频流媒体等多媒体业务的服务质量。     

无线网络中视频流的协作传输研究分析

提出一种两跳的协作传输方案,该方案利用无线信道广播特性,并结合应用层视频包的信息,通过选择成功监听到数据包的节点来承担协作传输任务,以此来降低重传次数,降低包的接入和服务延时,提高传输效率,以解决在无线环境下流媒体传输存在丢包率高、吞吐量受误码率影响、端到端的传输延时等QoS问题.     

An expandable time-division circuit switching LSI and networkarchitecture for broadband ISDN

A broadband network architecture is proposed that integrates multimedia services, such as data, video, and telephony information, using 52-Mb/s based STM-paths at the user network interface (UNI). The user can access any new service via the STM-based access network via either synchronous transfer mode (STM) switching or asynchronous transfer mode (ATM) switching. STM circuit switching supports long duration, constant bandwidth data transfer services such as video and high-definition television (HDTV) distribution and will also be used for the crossconnect system. Circuit switching can provide transparent transmission during long connection periods. This paper also proposes an expandable time-division switch architecture, an expandable time-division switching LSI, and an expandable switching module for small to large size system applications. The proposed time-division switching LSI, module, and system handle 52-Mb/s bearer signals and have throughputs of 2.4 Gb/s, 10 Gb/s, and 40 Gb/s, respectively. The time-division switch realizes video distribution with 1:n connections. Finally, a local switching node that features an expandable 52-Mb/s time-division circuit switching network is shown for multimedia access networking     

An adaptive congestion control scheme for real time packet videotransport

We show that modulating the source rate of a video encoder based on congestion signals from the network has two major benefits: the quality of the video transmission degrades gracefully when the network is congested and the transmission capacity is used efficiently. Source rate modulation techniques have been used in the past in designing fixed rate video encoders used over telephone networks. In such constant bit rate encoders, the source rate modulation is done using feedback information about the occupancy of a local buffer. Thus, the feedback information is available instantaneously to the encoder. In the scheme proposed, the feedback may be delayed by several frames because it comes from an intermediate switching node of a packet switched network. The paper shows the proposed scheme performs quite well despite this delay in feedback. We believe the use of such schemes will simplify the architecture used for supporting real time video services in future nationwide gigabit networks     

Interference-aware node access scheme in UAV-aided VANET

In vehicular Ad Hoc network (VANET),frequent link handovers and channel interference can lead to increased transmission delay and decreased network throughput.To address the issues,unmanned aerial vehicle (UAV) were introduced to cooperate with vehicles and construct UAV-assisted air-ground integrated VANET.An interference-aware node access scheme was proposed.The node access problem was formulated as a multi-objective optimization problem considering link transmission rate,link handovers and transmit power.Then the optimization problem was decomposed into two convex optimization sub-problems by dual decomposition method,the sub-problem jointly optimizes handovers and link transmission rate while the sub-problem optimizes the transmit power based on link reliability.Finally,simulation results show that the proposed mechanism can effectively improve data delivery ratio,average end-to-end delay and network throughput.     

QoE-aware video cooperative caching and transmission mechanism based on TWDM-PON and C-RAN

The quality of user experience suffers from performance deterioration dramatically due to the explosively growing data traffic.To improve the poor performance of cell-edge users and heavy-load cell users,which caused by dense network and load imbalance respectively,an QoE-aware video cooperative caching and transmission mechanism in cloud radio access network was proposed.Cooperative gain-aware virtual passive optical network was established to provide cooperative caching and transmission for video streaming by adopting collaborative approach in optical domain and wireless domain.Furthermore,user experience for video streaming,bandwidth provisioning and caching strategy were jointly optimized to improve QoE,which utilized the methods of dynamic caching in optical domain and buffer level-aware bandwidth configuration in wireless domain.The results show that the proposed mechanism enhances the quality of user experience and effectively improves the cache hit rate.     

基于光纤无线融合的射频无源光网络

文章认为为了实现更大的光接入网容量,并能更好地完成多业务的承载与融合,亟待发展下一代光接入网技术。文章提出了基于光纤无线融合的射频无源光网络(RPON),其不仅具有现有无源光网络系统低成本和易管控的特点,还具备光载射频系统灵活度高和移动性好的优势。该系统通过光生毫米波和波分复用的方式,实现了1Gb/s多媒体业务的单纤上下行传输,达到了10km光纤和5m无线的接入距离,能够满足低成本化推广应用要求。     

Cross-layer architecture for scalable video transmission in wireless network

Multimedia applications such as video conference, digital video broadcasting (DVB), and streaming video and audio have been gaining popularity during last years and the trend has been to allocate these services more and more also on mobile users. The demand of quality of service (QoS) for multimedia raises huge challenges on the network design, not only concerning the physical bandwidth but also the protocol design and services. One of the goals for system design is to provide efficient solutions for adaptive multimedia transmission over different access networks in all-IP environment. The joint source and channel coding (JSCC/D) approach has already given promising results in optimizing multimedia transmission. However, in practice, arranging the required control mechanism and delivering the required side information through network and protocol stack have caused problems and quite often the impact of network has been neglected in studies. In this paper we propose efficient cross-layer communication methods and protocol architecture in order to transmit the control information and to optimize the multimedia transmission over wireless and wired IP networks. We also apply this architecture to the more specific case of streaming of scalable video streams. Scalable video coding has been an active research topic recently and it offers simple and flexible solutions for video transmission over heterogeneous networks to heterogeneous terminals. In addition it provides easy adaptation to varying transmission conditions. In this paper we illustrate how scalable video transmission can be improved with efficient use of the proposed cross-layer design, adaptation mechanisms and control information.     

Federated learning based intelligent edge computing technique for video surveillance

With the explosion of global data,centralized cloud computing cannot provide low-latency,high-efficiency video surveillance services.A distributed edge computing model was proposed,which directly processed video data at the edge node to reduce the transmission pressure of the network,eased the computational burden of the central cloud server,and reduced the processing delay of the video surveillance system.Combined with the federated learning algorithm,a lightweight neural network was used,which trained in different scenarios and deployed on edge devices with limited computing power.Experimental results show that,compared with the general neural network model,the detection accuracy of the proposed method is improved by 18%,and the model training time is reduced.     

CSMA/CA‐based medium access control for indoor millimeter wave networks

Millimeter wave (mmWave) communication is a promising technology to support high‐rate (e.g., multi‐Gbps) multimedia applications because of its large available bandwidth. Multipacket reception is one of the important capabilities of mmWave networks to capture a few packets simultaneously. This capability has the potential to improve medium access control layer performance. Because of the severe propagation loss in mmWave band, traditional backoff mechanisms in carrier sensing multiple access/collision avoidance (CSMA/CA) designed for narrowband systems can result not only in unfairness but also in significant throughput reduction. This paper proposes a novel backoff mechanism in CSMA/CA by giving a higher transmission probability to the node with a transmission failure than that with a transmission success, aiming to improve the system throughput. The transmission probability is adjusted by changing the contention window size according to the congestion status of each node and the whole network. The analysis demonstrates the effectiveness of the proposed backoff mechanism on reducing transmission collisions and increasing network throughput. Extensive simulations show that the proposed backoff mechanism can efficiently utilize network resources and significantly improve the network performance on system throughput and fairness. Copyright © 2014 John Wiley & Sons, Ltd.     

一种基于EDCA的视频数据包动态映射算法

为了改善无线局域网中视频流的传输性能,该文提出一种基于增强分布式协调接入机制(EDCA)的动态映射算法。该算法首先建立视频数据包重要性排序模型,统计EDCA各个访问类的平均服务率,然后根据其可用资源动态地将排序后的视频数据包映射到不同的访问类中进行传输。该方法改进了EDCA机制中对数据包的静态映射机制,能够充分利用网络资源,从而改善了视频流在无线局域网中的传输性能。实验结果表明,该文提出的方法降低了数据包的传输延迟,提高了重建图像的质量。     

Fiber Optic Transport Systems for Present and Future Local Networks

This paper describes fiber optic transport systems for present and future local networks. The present most important fiber optic system in a local network emerges as a broad-band video distribution system, because large-scale system introduction might be attained only for distributed video services. The system architecture and system parameters are presented. As for future integrated services, a highspeed digital transmission system and local network architecture are very important. The network architecture should be constructed to meet the demands for increased flexibility, capacity, reliability, and economy. Considering expected future demands and technologies, a new fiber optic local network architecture is proposed. The architecture's main features are the use of transmission processing nodes and a multilane-ring structure in subscriber transfer networks in combination with star-shaped subscriber access lines.     

基于动态复合优先级的海上节点网络选择算法

针对海上移动节点完成业务时出现高优先级业务完成率低、业务拥堵率大、网络接入算法对波动环境适应性不足的问题,提出一种基于动态复合优先级的网络接入算法.首先,移动节点收集周围机动站点的网络属性参数,计算产生业务的执行紧迫性和剩余价值,再将不同类型业务的参数权重加入VIKOR法,形成最终的动态复合优先级,针对环境网络参数提供...     

可生存光纤—无线融合宽带接入网规划方法

光纤—无线融合（fiber-wireless,FiWi）宽带接入网的出现不仅为随时随地的灵活宽带接入提供了新的技术参考,同时也为可生存宽带接入网的低成本设计增加了研究契机。研究了可生存FiWi接入网的网络规划问题,提出一种基于无线重路由保护的可生存网络规划方法。当任意光纤链路断裂时,失效的光网络单元可通过无线重路由将业务转移到其他可用的光网络单元承载。重点解决了无线路由器部署、备份射频接口配置及光网络单元容量分配的联合优化问题,目标是通过最小化网络部署成本实现业务的完全保护。采用整数线性规划方法获得了小规模网络规划问题的最优解,同时提出了适用于大规模网络规划问题的启发式算法。仿真结果证实了所提方法在降低网络部署成本方面的有效性。     

认知 mesh 网络服务区分的动态频谱接入策略

动态频谱接入策略是实现认知无线电网络高效利用频谱的关键。与传统认知无线电网络不同,认知mesh网络中不同QoS需求的多类型业务共同接入,为适应这一特点,提出服务区分的动态频谱接入策略。策略依据业务的QoS需求确立优先级,针对不同优先级业务采取不同的信道接入方案,实时业务依据最优传输延迟期望选择接入信道集合,在减小传输延迟的同时降低数据传输过程授权用户出现的概率,普通业务选择最优理想传输成功概率的信道,降低信道切换概率。理论与实验结果表明,与传统的认知网络频谱接入策略相比,提出的策略能提供不同业务的服务区分,满足实时业务的低延迟需求,降低数据传输的中断率,同时在授权信道空闲率与网络负载较大时吞吐量性能较优。     

Power Efficient Video Multipath Transmission over Wireless Multimedia Sensor Networks

This paper proposes a power efficient multipath video packet scheduling scheme for minimum video distortion transmission (optimised Video QoS) over wireless multimedia sensor networks. The transmission of video packets over multiple paths in a wireless sensor network improves the aggregate data rate of the network and minimizes the traffic load handled by each node. However, due to the lossy behavior of the wireless channel the aggregate transmission rate cannot always support the requested video source data rate. In such cases a packet scheduling algorithm is applied that can selectively drop combinations of video packets prior to transmission to adapt the source requirements to the channel capacity. The scheduling algorithm selects the less important video packets to drop using a recursive distortion prediction model. This model predicts accurately the resulting video distortion in case of isolated errors, burst of errors and errors separated by a lag. Two scheduling algorithms are proposed in this paper. The Baseline scheme is a simplified scheduler that can only decide upon which packet can be dropped prior to transmission based on the packet’s impact on the video distortion. This algorithm is compared against the Power aware packet scheduling that is an extension of the Baseline capable of estimating the power that will be consumed by each node in every available path depending on its traffic load, during the transmission. The proposed Power aware packet scheduling is able to identify the available paths connecting the video source to the receiver and schedule the packet transmission among the selected paths according to the perceived video QoS (Peak Signal to Noise Ratio—PSNR) and the energy efficiency of the participating wireless video sensor nodes, by dropping packets if necessary based on the distortion prediction model. The simulation results indicate that the proposed Power aware video packet scheduling can achieve energy efficiency in the wireless multimedia sensor network by minimizing the power dissipation across all nodes, while the perceived video quality is kept to very high levels even at extreme network conditions (many sensor nodes dropped due to power consumption and high background noise in the channel).     

Supporting multimedia streaming and best‐effort data transmission over IEEE 802.11e EDCA

As demand for broadband multimedia wireless services increases, improving quality of service (QoS) of the widely deployed IEEE 802.11 wireless LAN (WLAN) has become crucial. To support the QoS required by a wide range of applications, the IEEE 802.11 working group has defined a new standard: IEEE 802.11e. In this paper, we propose a measurement‐based dynamic media time allocation (MBDMTA) scheme combined with a concatenating window scheme to support real‐time variable bit rate (rt‐VBR) video and best‐effort (BE) data transmission using IEEE 802.11e enhanced distributed channel access (EDCA). To provide the QoS guarantee for rt‐VBR video, the proposed MBDMTA scheme dynamically assigns channel time to the rt‐VBR video based on the estimate of the required network resources. On the other hand, the concatenating window scheme controls the contention window (CW) ranges of different priority flows such that real‐time services always have higher channel access probability, thus achieving the capability of preemptive priorities. In addition, the concatenating window scheme preserves fairness among flows of the same class and attains high channel utilization under different network conditions. Simulation results demonstrate that the throughput and delay performance improve significantly for the transmission of rt‐VBR video and BE traffic as compared to those for the 802.11e EDCA specification. It is also revealed that combining the two proposed schemes provides seamless integration and reliable transmission of digital video and data service within the 802.11e EDCA framework. Copyright © 2007 John Wiley & Sons, Ltd.     

基于IMS技术的三网融合网络多媒体业务部署

提出了基于云计算架构的三网融合网络多媒体视频业务部署技术,解决了三网融合网络海量终端用户访问及多媒体业务及用户的管理等问题.给出了三网融合网络的多媒体视频业务管理模型,并且详细说明了多媒体视频应用服务器及客户端的功能模块,以实例方式说明了QoS策略决策过程.为三网融合网络多媒体业务部署提供了指导性的技术方案.     

IEEE 802.11中多速率多节点公平的数据分组长度调整策略

在深入剖析多速率机制导致不公平性根源的基础上,提出了基于传输速率的数据分组长度调整(TRPSA)策略,该策略保证了传输速率不同的节点能公平地占用无线信道。理论证明和仿真验证了该策略能有效实现多速率多节点情况下的公平性,显著提高网络性能。该策略只需对IEEE 802.11做细小修改,易于在实际网络中实现和推广。