关于IP数字电视前端的新思考

三网融合促进广电运营商由单向广播业务向双向互动业务转变,广电运营商与电信运营商在业务上同质化发展,形成交叉和竞争,业务内容的相近和相同驱使双方在网络结构上相互渗透。近几年来广电运营商根据新业务的需求,在网内引入互联网技术,使传统ASI前端向IP化前端过渡,以打破ASI前端在业务拓展方面的限制,不断探索IP前端下增值业务的发展,并不断挖掘IP前端在新的市场环境中所能起到的作用,阐述IP前端在技术上的优势并讨论其对广电运营商平台建设和对新业务的有力支撑。     

Recent optimization models and trends in location,relocation, and dispatching of emergency medical vehicles

Over the past 10 years, a considerable amount of research has been devoted to the development of models to support decision making in the particular yet important context of Emergency Medical Services (EMS). More specifically, the need for advanced strategies to take into account the uncertainty and dynamism inherent to EMS, as well as the pertinence of socially oriented objectives, such as equity, and patient medical outcomes, have brought new and exciting challenges to the field. In this context, this paper summarizes and discusses modern modeling approaches to address problems related to ambulance fleet management, particularly those related to vehicle location and relocation, as well as dispatching decisions. Although it reviews early works on static ambulance location problems, this review concentrates on recent approaches to address tactical and operational decisions, and the interaction between these two types of decisions. Finally, it concludes on the current state of the art and identifies promising research avenues in the field.     

HIAWSC： An Immune Algorithm Based Heuristic Web Service Composition Framework

The introduction of of web services has led to web service composition being a focus of many researchers. Composing web services using workflows is seen as the most realistic method from an industrial viewpoint. Amongst other method, the use of natural computing methods has been proposed previously to automate web service composition. The need for a fast response when computing the most suitable sequence of services is addressed in this paper. In particular, we propose a novel heuristic immune algorithm with an efficient encoding and mutation method. The algorithm involves two steps： an immune selection operation, which is maintaining antibody population diversity and the clonal selection. The use of a vaccine during the evolution provides heuristic information that accelerates the convergence. Our experimental results illustrate that the proposed heuristic immune algorithm is very effective in improving the convergence speed. We also provide a schema analysis for this method.     

Metrics in Sharing Video Relationship-Networks

At present the video sharing service has gradually became one of the Internet killer applications. It is crucial to the service providers that understand the intrinsic nature of Sharing video relationshlp-networks （SVRNs） formed by video related list. This paper investigates the relationships between sharing videos using complex networks theory. New metrics are introduced to model and characterize the SVRN from topological view. Through extensive study on YouTub% a set of key findings are revealed. The results show that the node in- degree of SVRNs follows the power-law distribution and its entropy remains stable over time. The topology also exhibits an assortative property and obvious clustering phenomenon. But the rich-club phenomenon is not evident compared with the Internet AS-level topology. This research will enable the service providers to optimally plan and operate their video-based services.     

Quality perception when streaming video on tablet devices

The proposed work aims at analyzing the quality perceived by the user when streaming video on tablet devices. The contributions of this paper are: (i) to analyze the results of subjective quality assessments to determine which Quality of Service (QoS) parameters mainly affect the users’ Quality of Experience (QoE) in video streaming over tablet devices; (ii) to define a parametric quality model useful in system control and optimization for the considered scenarios; (iii) to compare the performance of the proposed model with subjective quality results obtained in alternative state-of-the-art studies and investigate whether other models could be applied to our case and vice versa.     

Dynamic connection provisioning with shared protection in IP/WDM networks

Internet protocol (IP) traffic connections arrive dynamically at wavelength‐division multiplexing (WDM) network edges with low data rates compared with the wavelength capacity, availability, and quality‐of‐service (QoS) constraints. This paper introduces a scheme to be integrated into the control and management plane of IP/WDM networks to satisfy the availability and QoS required for IP traffic connections bundled onto a single wavelength (lightpath) in WDM networks protected by shared‐backup path protection (SBPP). This scheme consists of two main operations: (i) routing multi‐granular connections and traffic grooming policies, and (ii) providing appropriate shared protection on the basis of subscribers’ service‐level agreements in terms of data rate, availability, and blocking probability. Using the Markov chain process, a probabilistic approach is developed to conceive connection blocking probability models, which can quantify the blocking probability and service utilization of M:N and 1:N SBPP schemes. The proposed scheme and developed mathematical models have been evaluated in terms of bandwidth blocking ratio, availability satisfaction rate, network utilization, and connection blocking probability performance metrics. The obtained research results in this paper provide network operators an operational setting parameter, which controls the allocation of working and backup resources to dynamic IP traffic connections on the basis of their priority and data rate while satisfying their requirements in terms of bandwidth and availability. Copyright © 2013 John Wiley & Sons, Ltd.     

A Location Privacy Preserving Solution to Resist Passive and Active Attacks in VANET

Existing location privacy- preserving methods, without a trusted third party, cannot resist conspiracy attacks and active attacks. This paper proposes a novel solution for location based service （LBS） in vehicular ad hoc network （VANET）. Firstly, the relationship among anonymity degree, expected company area and vehicle density is discussed. Then, a companion set F is set up by k neighbor vehicles. Based on secure multi-party computation, each vehicle in V can compute the centroid, not revealing its location to each other. The centroid as a cloaking location is sent to LBS provider （P） and P returns a point of interest （POI）. Due to a distributed secret sharing structure, P cannot obtain the positions of non-complicity vehicles by colluding with multiple internal vehicles. To detect fake data from dishonest vehicles, zero knowledge proof is adopted. Comparing with other related methods, our solution can resist passive and active attacks from internal and external nodes. It provides strong privacy protection for LBS in VANET.     

基于密度权期望最大与分裂合并策略的线状模式挖掘

该文针对非线性数据集中线状模式的挖掘问题,提出一种基于密度权期望最大(EM)与分裂合并策略的回归算法。算法基于有限混合模型思想,使用点向式方程定义线状模式表示,将网格密度作为调节权值引入EM过程,有效降低了回归落入局部极值的可能性。同时,引入分裂合并策略,使得算法能够解决连通性问题,并且即使在挖掘数设置与本质线状模式数不相符时也能获得正确结果。实验结果表明,算法对挖掘数设置不敏感,能够正确挖掘出噪声环境下数据集的线状模式。     

基于纳什均衡的需求响应多用户策略研究

随着能源互联网的出现和智能电网的发展,使得电能供给与电能需求能够更紧密的联系,也促进了电力交易市场条件下需求响应的信息化和智能化,用户根据自身情况在需求响应市场上进行出价与竞争,也更好的反映了电能的市场价值。本文结合智能电网下的需求响应市场,描述了多用户对电能竞争的一般场景与模型,从理论和算法上分析用户出价与市场调节的最优化问题,在给定的一般情况下,证明了存在一个纳什均衡,使得市场竞价能得到一个最终解的集合,实现用户竞争后的稳定解,同时给出了优化问题解的一个高效算法。     

探讨基于QoS管控的差异化4G网络服务

随着高流量4G计划的普及以及在线游戏,在线视频,即时消息等移动互联网应用的快速发展,4G网络负载变得越来越繁重。在网络资源不足的情况下,电信运营商必须为不同类型的用户和服务提供差异化的网络服务,以吸引和留住高价值用户,提高网络的竞争力。本文尝试以无线资源利用率为触点,联动核心网与无线侧能力,通过实施基于Qo S(Quality Of Service)管控的差异化调度方案,在无线网络资源不足时,为不同类型的4G用户提供不同的网络感知服务。