Multiattribute‐based routing for lifetime maximization in opportunistic mobile social networks

With the advancement in wireless technology and portable devices, smart phones have become one of the belongings of human being. People share their data online, but it has limitations due to transmission range and mobility. Yet opportunistic mobile social network enables users to share data online even if there is no connected path between source and destination. The widespread use of mobile phones equipped with WiFi, Bluetooth, and several other components and contact opportunities among humans bridge the gap between internet available and nonavailable area. In this paper, we have proposed a new routing approach which utilizes both spatial and temporal attributes of user such as probability to meet a particular location and remaining intercontact time between two nodes to select better relay nodes. Generally, users visit different locations such as sports stadium and mall, with varying probability. Users with similar interest form group, and each user has different intercontact time with other users according to their point of interest and visiting pattern. By utilizing multiattributes, different forwarding strategies have been devised for both inter and intragroup routing. The proposed work “point of interest (PoI)‐based routing” is implemented in Opportunistic Network Environment simulator, and the performance is analysed in terms of delivery rate, latency, overhead, goodput, and energy consumed. The simulation results show that PoI diminishes 23% of overhead and yields 24% improvement in goodput over the state‐of‐the‐art protocol. Thus, the simulation results reveal that our proposed work provides the balance between routing performance and resource consumption.     

DTN网络中一种基于灰色预测和状态估计的位置预测方法

典型的延迟容忍网络（DTN）中,由于中继节点间的链路延时和间歇性中断,用于预测运动节点位置的观测数据在传输中常常滞后、丢失。为了在这样的环境下对这些节点的位置进行及时、准确的预测,该文首先建立了基于方位角的节点运动状态方程,然后利用灰色预测理论对方位角进行预测,再基于该预测值利用扩展卡尔曼滤波算法对目标节点的坐标值进行递推估计。仿真分析表明,采用这样的位置预测算法,可以克服DTN网络中观测数据经常缺失的缺点,可实现对DTN网络节点的位置进行在线预测,相较于对坐标值进行直接预测,其准确性有进一步提高。     

DTN中基于节点价值的效用路由算法

为了解决延迟容忍网络(DTN)中传统路由算法中消息被分配的网络资源不均衡及节点负载不均衡问题,结合消息效用值提出了一种基于节点价值的效用路由算法。算法根据动态改变的消息效用值选择最高优先级的消息(具有最小TTL和到目的节点最短距离的消息)进行转发,以使得为每个消息分配的网络资源相对均衡;同时,根据节点的价值(与节点速度和剩余缓存有关)选择下一跳节点,以平衡每个节点的负载;另外,算法还采用了一定的消息管理机制及时清除缓存空间。通过仿真实验及性能分析表明,该算法在传输成功率、传输延迟和网络开销上都有明显的改善。因此,通过充分利用网络资源提高了算法的整体性能。     

深空DTN多属性决策拥塞控制的研究

针对深空时延容忍网络(DTN)因节点存储空间有限造成的拥塞问题,提出了一种改进的多属性决策选择下一跳节点的策略。其基本思想是根据节点的存储空间占用率将节点状态划分成普通、半拥塞和拥塞三个状态,结合节点接收数据包的历史记录,在此基础上采用多属性决策理论选择最优的下一跳节点,从而达到预防拥塞的目的。仿真结果表明,与原策略相比,提出的策略在单个节点队列长度、平均队列长度、数据包接收率和数据包平均分发时间上有明显的改善,有效地缓解了网络拥塞。     

节点密度感知的容迟网络路由协议*

为适应容迟网络的动态变化,提高路由性能,结合空间节点分布和节点度中心性,提出一种节点密度感知的容迟网络路由协议DAR。该协议引入移动模型的节点分布,通过感知节点当前所处位置的节点密度,动态选择在网络中传播的消息副本数量,并根据节点的度中心性选择中继和分配消息副本数量。仿真结果表明,DAR能够提高传输率、降低传输延迟,在一定程度上降低了资源消耗。     

Minimum delay algorithm based on time aggregated graph in DTN network

The DTN network has the characteristics of dynamic topology change,thus the routing algorithm of static network can not solve the routing problem of time-varying network,and can not support fast transmission of given tasks.The existing time-variant routing algorithm CGR (contact graph routing) uses the earliest contact to obtain the shortest path,but because of the influence of the order of the connectivity period,the CGR algorithm has low link utilization.To solve this problem,the method of finding the shortest path was proposed.Besides,in order to characterize the relation between the different connect periods of the same link,the time series of node cache was added to the time aggregated graph.Based on this,the end-to-end multi-path shortest delay routing algorithm for the known task requirements was proposed.Finally,the feasibility of the algorithm was proved by an example.     

天基信息网络的软件定义网络应用探析

现有各种空间、地面网络节点的互连互通,在一定程度上可满足特定应用需求,但由于各节点在空间、物理以及功能的局限,限制了天基信息高效传输、融合以及按需地应用。分析了天基信息网络的发展趋势,提出了网络架构构想,并对主要关键技术的研究方向进行了梳理。在空间核心节点上采用软件定义的多功能载荷平台,并基于软件定义网络( SDN)架构和空间容中断网络协议构建天基信息网络。通过资源虚拟化、处理多元化、应用无阻化的方式,保障天基信息网络适应信息按需定制和高效共享等应用需求。     

深空通信网络协议的发展与展望

分析了发展深空通信网络的需求,结合深空通信网络的特点,对深空通信网络协议体系和路由策略等的技术现状进行了综述,对其中的关键技术进行了分析,并对深空通信网络的未来发展进行了展望。     

容迟网络中传染路由协议优化

针对传染路由协议（EPI）的泛洪机制会造成容迟网络资源浪费的问题,提出将节点间的历史相遇信息引入传染路由协议的改进算法（EPI-HT）,以达到准确选择数据下一跳转发节点的目的。仿真结果表明,改进后的EPI-HT比EPI明显抑制了数据泛洪传输,可提高交付率,同时降低端到端时延。     

稀疏车辆Ad Hoc网络中基于受控机制的自适应Epidemic路由算法

针对传统Epidemic的性能缺陷,提出了基于控制机制的自适应Epidemic 路由(Ad-EPI)算法。Ad-EPI算法采用受控洪泛机制和信息副本控制等机制,并引入信息生存时间和自适应控制策略,在确保有较高到达率的条件下,取得了峰值传输控制、带宽资源占用、缓存利用和时延等方面的综合平衡。在VanetMobiSim仿真平台上,对Ad-EPI算法进行了VC++6.0编程实现和仿真,并与经典Epidemic算法进行了性能对比。仿真结果证实,Ad-EPI算法与Epidemic比较,付出较小的时延代价,却具有了带宽占用减少27.62%,峰值平均降低15.19%,缓存利用率提高92.14%等优势。Ad-EPI算法在上述三个方面的性能提升,具有工程意义和应用价值。