基于拓扑感知的可重构服务承载网动态重构算法

可重构信息通信基础网络通过构建服务承载网的方式为业务提供自适应的承载服务。针对高效利用有限底层资源的问题,提出一种基于资源关键度进行动态映射的服务承载网构建算法。算法将通过节点或链路的最短路径数作为资源关键度的衡量指标,区别对待底层资源;并实时动态感知关键资源的使用状况,依据不同业务需求对服务承载网进行自适应调整。仿真结果表明,算法在构建成功率、收益花费比和资源均衡度等方面均具有良好性能。     

Beamforming for inter‐relay interference reduction in MIMO‐aided two‐path successive relaying

To effectively reduce the inter‐relay interference (IRI) in two‐path successive relaying, two beamforming schemes are proposed in this paper, utilizing multiple‐antenna relay nodes. Specifically, the two cooperation nodes perform receive combining of the source signal and transmit beamforming of the relayed signal alternately in the successive relaying process. As a result, the IRI between them can be effectively suppressed, thanks to the additional degree of freedom provided by the multiple‐input multiple‐output inter‐relay channel. In the first beamforming scheme, the source‐to‐destination signal‐to‐interference‐plus‐noise ratios (SINR) of separate paths are maximized with approximation, leading to a minimum variance distortionless response beamformer under the high SINR condition. To further improve the system performance, noting that the received SINRs of the two paths have impact on each other due to the mutual coupling of the beamformers, the sum of mean squared errors from these two transmission paths is minimized in the second scheme. Based on this performance criterion, a suboptimal beamformer design is developed numerically through cyclic minimization of the sum of mean squared error cost function. Simulation results demonstrate the superiority of both proposed beamforming schemes in terms of symbol error rate and the achievable system rate, in particular, at high IRI levels. Copyright © 2016 John Wiley & Sons, Ltd.     

网络功能虚拟化中的性能感知服务组合优化

服务功能链是网络功能虚拟化的重要支撑,为了构建满足功能和性能需求的服务功能链,需要建立服务的性能模型,从而产生基于性能的服务组合优化问题。一种基于性能模型的服务组合优化问题被建模,并针对复杂约束情况下的无效解干扰,提出了改进的模拟退火算法,该算法包含基于层次属性的产生函数和基于偏离度的目标函数。仿真结果表明,该算法提高了21%的服务组合成功率,同时降低了组合成本和时间消耗。仿真结果验证了所提算法的有效性。     

Queueing model based resource optimization for multimedia cloud

Multimedia cloud is a specific cloud computing paradigm, focusing on how cloud can effectively support multimedia services. For multimedia service providers (MSP), there are two fundamental concerns: the quality of service (QoS) and the resource cost. In this paper, we investigate these two fundamental concerns with queueing theory and optimization methods. We introduce a queueing model to characterize the service process in multimedia cloud. Based on the proposed queueing model, we study resource allocation problems in three different scenarios: single-service scenario, multi-service scenario, and priority-service scenario. In each scenario, we formulate and solve the response time minimization problem and the resource cost minimization problem, respectively. We conduct extensive simulations with practical parameters of Windows Azure. Simulation results demonstrate that the proposed resource allocation schemes can optimally allocate cloud resources for each service to achieve the minimal response time under a certain budget or guarantee the QoS provisioning at the minimal resource cost.     

基于蚁群优化的无线多媒体传感器网络区分服务路由

无线多媒体传感器网络中存在多种类型的数据,而且这些数据的服务质量需求并不相同。针对这种情况,提出一种基于蚁群优化的区分服务路由协议（DSACO, differentiated service and ant colony optimization based routing protocol）。DSACO在网络分层的基础上通过限制蚂蚁的搜索范围以减少建立路由的时间和能量消耗,对不同服务质量需求的数据采用区分服务路由以满足不同类型数据的服务质量需求。仿真结果表明,新协议能够为多媒体数据的传输提供更好的QoS保障,在数据传输的平均时延、分组丢失率和能量消耗上优于已有路由协议。     

QoS-supporting video streaming system with minimum data service cost over heterogeneous wireless networks

This paper presents a video streaming system that supports quality-of-service by effectively consolidating multiple physical paths in a cost-effective way over heterogeneous wireless networks. In the proposed system, the fountain encoding symbols of compressed video data are transmitted through multiple physical paths concurrently to overcome the limitation of single path transmission and harmonize multiple physical paths with diverse characteristics effectively, and the number of transmitted packets is determined by considering the requested quality-of-service of video streaming and the data service cost. The proposed system is fully implemented in Java and C/C++, and tested over real WLAN and LTE networks. Experimental results are provided to demonstrate the performance improvement of the proposed system.     

基于显著特征的HEVC帧内率失真优化

引入感知因素的RDO算法和感知编码可以提高编码视频主观质量,但也产生了明显的率失真性能损失。针对上述问题,提出了一种基于显著特征的 RDO 方法。首先探索了 HEVC 编码树单元的码率分布和显著特征之间的相关性,提出显著码率先验模型并确定了模型的初始参数;然后建立了码率差异最小化的率失真代价模型,并根据该模型推导得到自适应拉格朗日乘子计算方法;最后设计了模型参数更新规则。实验结果表明,算法在率失真性能基本不变的情况下,提高了视频的主观质量。     

智慧协同网络服务内容在传输路径上的缓存分配策略

针对智慧协同网络提出一种服务内容在传输路径上的缓存分配策略。该策略根据服务内容的流行度部署其在传输路径上的缓存位置,以求充分、高效地发挥网络缓存作用,进而提升网络的总体性能。所提分配策略分别在5层树型拓扑和由279个节点组成的真实网络拓扑中进行了性能测试。结果显示,该策略在所测的性能参数中表现出色,就平均服务获取距离而言,较命名数据网络（NDN, named data nerworking）所使用的LCE（leave copy everywhere）策略,其性能提高20%以上。     

基于边缘计算的数据密集型服务部署

日益增长的数据量对数据处理的要求越来越高,于是出现了数据密集型服务。在解决复杂问题时,多个数据密集型服务通常会形成一个服务组合。由于服务组件之间存在大量的数据传输,巨大的传输时延会对系统的整体性能造成影响。在边缘计算环境中,基于否定选择算法,为降低服务组合中的数据传输时间提出了一种优化部署策略。首先,给出了此类数据密集型服务组件部署问题的定义,并为该部署问题构建优化模型;然后,设计了一种否定选择算法来获取最佳的部署方案;为了评估该算法的适用性和收敛性,使用遗传算法和模拟退火算法与其对比,结果显示,提出的算法在这种数据密集型服务组件的部署问题中表现得更为出色。     

Service function chain construct algorithm based on reliability

With the continuous expansion of network size and content quantity,network operators often face the problem of data transmission interruption,thus how to improve the reliability of data transmission has become a research hotspot.Started with the huge advantages of NFV environment over traditional TCP/IP architecture based on the background that every network node has the capability of security service,a reliability algorithm for constructing functional service chains was proposed.First,the network topology was introduced and abstracted it into a digraph for a better analyzation.Then,several quantitative indices were used to define the upper and lower bounds of failure probability and resolved the model through a heuristic algorithm.The experimental results show that the proposed algorithm increases the reliability of service chain selection and spends less time.     

具有QoS保证的分布式服务组合策略

现有的服务组合方法多是获取候选服务节点的信息,在集中式组合引擎上搜索路径.这种集中式方法不仅具有单点失效、可扩展性差等缺点,而且候选服务的QoS没有保证,服务搜索空间过大,组合效率较低.文章提出了一种分布式的服务组合方法(BDDSC),将分散在网络中性能有保证的服务节点构建成服务覆盖网络,使各个节点协作执行进行动态服务...     

基于ACS的无线传感器网络区分服务路由算法

针对无线传感器网络中数据传输的不同要求,将QoS分为3类,根据无线链路的特点提供区分服务。利用博弈论分析了数据传输在延迟、可靠性与网络能量开销之间的关系,基于改进的蚁群优化算法ACS(ant colony system),设计了区分服务路由算法ADSGR(ant colony system based differentiated service and game-theory routing),依据不同QoS要求,选择适当的路由,提高网络的整体性能和资源利用率。实验结果表明,与现有算法相比,该算法在数据传输的延迟、可靠性和能量开销上具有更好的性能。     

Joint interference coordination approach in femtocell networks for QoS performance optimization

Future heterogeneous networks with dense cell deployment may cause high intercell interference. A number of interference coordination (IC) approaches have been proposed to reduce intercell interference. For dense small‐cell deployment with high intercell interference between cells, traditional forward link IC approaches intended to improve edge user throughput for best effort traffic (ie, file transfer protocol download), may not necessarily improve quality of service performance for delay‐sensitive traffic such as voice over long‐term evolution traffic. This study proposes a dynamic, centralized joint IC approach to improve forward link performance for delay‐sensitive traffic on densely deployed enterprise‐wide long‐term evolution femtocell networks. This approach uses a 2‐level scheme: central and femtocell. At the central level, the algorithm aims to maximize network utility (the utility‐based approach) and minimize network outage (the graphic‐based approach) by partitioning the network into clusters and conducting an exhaustive search for optimized resource allocation solutions among femtocells (femto access points) within each cluster. At the femtocell level, in contrast, the algorithm uses existing static approaches, such as conventional frequency reuse (ReUse3) or soft frequency reuse (SFR) to further improve user equipment quality of service performance. This combined approach uses utility‐ and graphic‐based SFR and ReUse3 (USFR/GSFR and UReUse3/GReUse3, respectively). The cell and edge user throughput of best effort traffic and the packet loss rate of voice over long‐term evolution traffic have been characterized and compared using both the proposed and traditional IC approaches.     

A Comprehensive Service Discovery Solution for Mobile Ad Hoc Networks

Service discovery is an integral part of constructing self-configuring Mobile Ad Hoc Networks (MANETs). While several service discovery protocols have been developed, most of them are designed for infrastructure-based networks and thus not suitable to be used in MANETs. Due the volatile nature of MANET, service discovery protocols designed for MANETs often suffer from problems. Firstly, they have limited scalability due to the extensive use of broadcast communication. Secondly, they usually lack context-aware selection mechanisms and feature only reduced interaction standards. This paper proposes a network layer supported comprehensive service discovery solution that addresses the above issues and provides a solution in two parts. First it discusses a location-aware network layer routing protocol that groups mobile nodes into clusters while a gateway in each cluster is responsible for routing. Secondly, this paper proposes a service discovery protocol that utilizes directories for service discovery that interact with lower network layer gateway configurations. In this architecture, gateways are also used as directories for service discovery to improve performance. In doing so, we improve the system’s overall efficiency by eliminating the use of complex graph-based algorithms for maintaining clusters and establishing virtual backbones. Furthermore, this service discovery solution includes an agent-based context-aware service selection, and provides standard mechanisms for different types of service interaction. Jerry Tyan is a graduate student in the Department of Computing and Information Science at the University of Guelph in Guelph, Canada. Jerry holds a B.Sc. in Computer Science from Simon Fraser University in Vancouver, Canada. His research interests are in the area of service discovery protocols for mobile ad hoc networks. Qusay H. Mahmoud is an Assistant Professor in the Department of Computing and Information Science at the University of Guelph, and Associate Chair of the Distributed Computing and Wireless & Telecommunications Systems Technology program at the University of Guelph-Humber in Toronto, Canada. He received a B.Sc. in Data Analysis and an M.Sc. in Computer Science, both from the University of New Brunswick (Canada), and a Ph.D. in Computer Science from Middlesex University (UK). Dr. Mahmoud has published dozens of research papers and two books. Also, he has organized several research events, edited their proceedings, and presented tutorials at several international conferences worldwide. His research interests include wireless computing, agent technology, service discovery protocols, and Web-based systems. He is a member of the ACM and the IEEE Computer Society.This revised version was published online in August 2005 with a corrected cover date.     

移动自组织网络下一种基于可用性感知的服务选择方法

Service composition is considered to be an effective way for resource sharing and node collaboration in Mobile Ad hoc NETworks (MANETs) environment. In order to improve the reliability and shorten the response time of composite services, this paper first analyzes the node environments and network environments that affect the component services’ availability, and then proposes an Environment-aware Quantitative Evaluation Model for Service Availability (EQEM-SA). In addition, based on EQEM-SA, a service field concept is proposed as well as the availability attenuation equation, where the availability value is considered as the field strength. Then the service selection approach based on service field model is presented. The effectiveness of the proposed approach is illustrated and compared with related references, and the results of experimental evaluations indicate that our approach significantly reduces the failure rate and shortens the service delay.     

物联网环境中基于车联网与3G网络的跨层安全相关广播业务结构(英文)

As Vehicle Ad Hoc Networks (VANETs) is part of the applications of the Internet of Things (IoT), and Vehicles in VANETs periodically broadcast the beacon message for status advertisement to provide public safety, the impacts of the network parameters on the reliability of broadcast messages are investigated and discussed; meanwhile, a cross-layer safety-critical broadcast service architecture is proposed to obtain an optimized set of packet loss rate and delay based on the Neural Networks (NN) and Back Prop...     

云服务的自组织机制及性能分析

To improve the performance and robustness in service discovery, a self-organizing mechanism for service alliances of Service Providers (SPs) is proposed in this paper. According to the similarity of service content, an SP publishes its services in a partition of SPs to construct connections between highly similar SPs. These SPs constitute a self-organized distributed environment. A self-organizing protocol is designed to ensure the correctness of the construction of the alliances. The protocol consists of four stages — initiating stage, developing stage, developed stage and degradation stage. The experimental results demonstrate that this protocol ensures the self-property. The visualization of alliance developing stages illustrates that sub-alliances are split in balance and self-connected. Compared with the Random Walker algorithm, the time cost and the number of forwarded messages in alliance-based mechanism is lower in service discovery. On three typical topologies (Grid, Random-Graph, Power-Law), the success rate of service discovery is much higher, which shows that self-organized alliances are helpful to enhance the discovery performance.     

An adaptive retransmission‐based multipath transmission mechanism for conversational video

Conversational video service is characterized by high bandwidth demand and low delay requirement. Bandwidth and transmission schemes play an important role in providing high‐quality delivery service for point‐to‐point conversational video service. Multipath transmission is regarded as an effective way to aggregate bandwidth. Transmission schemes need to ensure the strict time relation between information entities and to alleviate the negative impact of packet loss on video quality. To achieve this, existing transmission schemes may incur either a large delay or a large amount of duplicated packets that are not suitable for conversational video service. In this paper, we propose an adaptive retransmission mechanism–based multipath transmission (MT‐AR) for conversational video service delivery. MT‐AR takes advantage of historical reception experience to timely detect packet loss with a certain degree of misjudgement. Receiver requests sender to retransmit the lost packet if the lost packet benefits the decoding. Adaptive playout speed adjustment and alternative path retransmission cooperatively optimize the performance of retransmission. Receiver slightly extends playout speed to reserve time for retransmission and accelerates playout speed to alleviate negative impact of cumulative extension. Multiple paths support to conduct retransmission on an optimal path selected from alternative paths to avoid continuous congestion or error on the original path. Finally, we conduct extensive tests to evaluate the performance of MT‐AR. Experimental results show that MT‐AR can effectively improve the quality of experience of conversational video service by retransmission.     

基于混杂社会网络的个性化Web服务推荐方法

为了缓解Web服务推荐中存在的冷启动和数据稀疏问题,以及满足用户个性化的需求,本文提出了基于混杂社会网络的Web服务推荐框架及算法.该网络加入了服务提供者这一元素,可提供更多的真实信息,有助于缓解冷启动问题.根据提出的服务推荐框架,设计了用户-候选服务信任值预测算法（Computing Trust Value,CTV）,以及服务推荐算法（Recommend Queue,RQ）.在真实数据集上建立实验,结果表明本文提出的方法在预测准确率MAE、RMSE,推荐准确率MAP、NDCG,以及填充率和覆盖率上都有所提高,有助于提升个性化推荐的性能.     

Construction mechanism for service path over reconfigurable service-centric network

In order to enhance the flexible and intelligent network's service ability,a novel architecture called recon-figurable service-centric network (ReSCNet) was proposed which decomposed traditional network capabilities and ser-vices into fine-grained network functional unit.Then based on service routing matrix algorithm to orchestrate and deploy atomic service flexibly,a service path was built which possess smaller cost,lower time delay,higher degree of load bal-ance and higher reliability.Finally,the performance of service routing matrix algorithm was evaluated on the innovation experiment platform NetFPGA-10G.The simulation results show that the algorithm has a better performance and can cus-tomize an optimal service path for users while meet the specific functions and performance constraints.