一种基于好友簇的社交网络中的时延容忍路由协议

社交网络是一种以便携式移动通信设备为节点的无线网络,通常由于其规模较大、结构复杂并且拓扑变化频繁,而成为时延容忍网络的一个典型应用场景。通过分析社交网络的特性,构建了基于好友群组的网络拓扑模型,并基于该模型,提出了一种基于簇结构的时延容忍路由协议。通过实验证明了该路由协议可以在保证较高路由性能的前提下有效控制由于数据副本传染造成的对网络资源的消耗。     

Improving routing protocol performance in delay tolerant networks using extended information

Delay tolerant networks (DTNs) are wireless mobile networks that do not guarantee the existence of a path between a source and a destination at any time. When two nodes move within each other’s transmission range during a period of time, they can contact each other. The contact of nodes can be periodical, predictable and nonpredictable. In this paper, we assume the contact of nodes is nonpredictable so that it can reflect the most flexible way of nodes movement. Due to the uncertainty and time-varying nature of DTNs, routing poses special challenges. Some existing schemes use utility functions to steer the routing in the right direction. We find that these schemes do not capture enough information of the network. Thus, we develop an extended information model that can capture more mobility information and use regression functions for data processing. Experimental results from both our own simulator and real wireless trace data show that our routing algorithms based on the extended information model can increase the delivery ratio and reduce the delivery latency of routing compared with existing ones.     

Dynamic Prediction based Multi Queue (DPMQ) drop policy for probabilistic routing protocols of delay tolerant network

Two most important issues should be considered to achieve data delivery in DTN networking: routing protocols for the network and intelligent buffer management policy for everyone node in the network. The routing scheme decides which messages should be forwarded when nodes meet, and the buffer management policy determines which message is purged when the buffer overflows in a node. This study proposes a buffer management policy named as Dynamic Prediction based Multi Queue (DPMQ) for probabilistic routing protocols. It works by classification of local buffer into three queues of messages, which are DCTL, HPTL and LPTL. The simulation results have proven that the DPMQ performs well as compared to DLA, DOA, MOFO, LIFO, LEPR and LIFO in terms of reducing the message relay, message drop, hop counts average and overhead while rising in the delivery probability.     

容迟网络多副本路由技术研究

容迟网络作为移动自组网和传感器网络的最新发展形式,在智能公路、生物监测、卫星通信、乡村通信、个人信息交换等领域具有十分广阔的应用前景。容迟网络路由设计是一个富有挑战性和前景的新兴研究领域,首先介绍容迟网络路由技术的基础及其分类,然后对其中的多副本路由算法进行深入研究和比较,最后结合该领域当前研究现状,对未来研究容迟网络多副本路由算法进行总结和展望。     

容延容断网络研究及进展

容延容断网络(Delay/Disruption Tolerant Networks, DTN)是基于星际网络而提出的一种异于传统网络的抽象网络模型。从网络协议、路由算法、组播和安全机制4个方面综述DTN的研究概况及进展,分析各种协议、算法、机制的性能及特点并进行比较,指出DTN研究面对的挑战和进一步发展方向。     

移动传感器网络中基于概率分布的动态的低冗余路由算法

受到节点移动、有限的存储空间及能量等因素的影响,容延迟移动传感器网络在将数据汇聚至Sink过程中伴随着较高的丢包率与数据冗余,传统的确定性路由机制难以应用。对此,利用节点在一定数量时间槽内与Sink点连通的概率分布,提出了一种动态的、分布式的路由算法。该算法充分利用了节点的移动性,使网络在保持低冗余的同时,具有较高的数据送达率。实验结果表明,在节点数多、移动速度快、节点传输距离大的网络中,该算法更具优势。     

DTN体系结构及关键技术研究综述

中断/延迟容忍网络(Disruption/ Delay Tolerant Network,DTN)是从Ad-hoc网络中抽象出来的一种全新的网络模型。与传统的无线移动自组织网络不同,该网络模型的应用场景具有高延迟、易中断等特点。高延迟、易中断的网络环境被称为受限网络。DTN作为一个针对受限网络的新兴研究领域,使用特殊的“存储-携带-转发”模式进行数据传递,以对抗受限网络中的高延迟和易中断带来的影响。它的发展将对未来军事战争、航天通信、抢险救灾等诸多场景提供更为可靠的通信保证。文中分析了DTN体系架构及其特性,研究了DTN路由协议并指出其适用的场景,最后总结了DTN研究中遇到的难点问题,并指出未来研究需要关注的方向。     

Delay-sensitive routing in multi-rate MANETs

A mobile ad hoc network (MANET) is a collection of mobile hosts, which can communicate by the aid of intermediate mobile hosts without utilizing a fixed infrastructure and centralized administration. Many MANET standards, such as 802.11a, 802.11b, and 802.11g, can be operated at various rates for Quality-of-Service (QoS) constrained multimedia communication to more efficiently use the limited resources of MANETs. Since the radio channel is shared among neighbors in MANETs, calculating one-hop delays and determining delay-sensitive routes using the IEEE 802.11 MAC are still two challenging problems. In this paper, we first exploit the busy/idle ratio of the shared channel to estimate one-hop delay based on varied data rates. Then by the aid of the estimated delay, a multi-rate routing protocol is proposed for selecting data rates and determining a route for admitting a flow with a requested delay. In MANETs, when a host is transmitting data packets, its neighbors are blocked (i.e., forbidden to send packets) since it shares the radio channel with its neighbors. We adopt the strategy by selecting the combination of data rates and a route in order to minimize the total blocking time to all hosts of the network for maximizing the network’s capacity, which is the number of flows admitted by the network. Simulation results show that the proposed method obtains a more precise one-hop delay than a very recent work, and the proposed protocol admits more flows than an existing protocol.     

An evolutionary approach towards contact plan design for disruption-tolerant satellite networks

Delay and disruption tolerant networks (DTNs) are becoming an appealing solution for satellite networks where nodes can temporarily store and carry in-transit data until a link with a suitable next-hop becomes available. Since satellite trajectories and orientation can be predicted, on-board routing schemes can base these forwarding decisions on a contact plan comprising all forthcoming communication opportunities. In general, contact plans are previously calculated on ground where their design can be optimized to consider not only available spacecraft resources but also the expected traffic which is largely foreseeable in space applications. Despite optimal contact plan design procedures exist, their computation complexity might result prohibitive even for medium-sized satellite networks. In this work, we propose an evolutionary algorithm to provide sub-optimal yet efficient and implementable contact plans in bounded time. In particular, we depict specific strategies such as encoding and repairing techniques to later evaluate the algorithm performance in a typical scenario demonstrating its usefulness for planning future DTN-based satellite networks.     

WDM网络中满足延迟和延迟差约束的分布式组播路由与波长分配算法

在WDM网络中,由于每条链路上可用波长是动态变化的,在考虑波长转换延迟时间的条件下,实现实时组播连接的路由与波长分配是十分困难的。论文提出了一种用于建立满足延迟时限和延迟差要求的实时组播连接的分布式路由与波长分配算法。该算法假定每个节点没有全局路由信息,只根据关联链路的信息进行路由选择,且将路由与波长分配统一进行。组播路由算法以Prim最小生成树算法为基础,生成一棵满足给定延迟时限的最小成本树。对不满足延迟时限的目的节点,通过增加回路边构造回路再消除长延迟路径的方式,加入到组播树中。对不满足延迟差的目的节点,采用重构Steiner树的方法,使其满足延迟差的要求。波长分配使用最少波长转换和负载平衡策略。     

基于大功率消息广播的DTMSN路由机制

提出一种基于基站大功率信号广播的延迟容忍移动传感器网络消息路由机制(High-power Broadcasting based Routing scheme,HBR)。该机制使用两个通信频率f₁ 和f₂,基站以恒定大功率在频率f₁上广播已经接收到的消息,网络中传感器节点根据基站广播信息计算自身转发概率并清理冗余消息副本,节点间利用频率f₂进行通信。为进一步提升网络性能,HBR优先传输转发阈值(M)小且生存时间短的消息,并合理进行消息队列管理。仿真结果表明,与几种经典的路由机制相比,HBR在消息传输成功率、传输延迟方面有着一定的优势。     

车载传感器网络的研究进展

车载传感器网络是一种建立在车载自组织网络基础上的以数据为中心的新型移动传感器网络。与传统传感器网络不同的是,车载传感器网络中的节点是高速移动的,从而导致网络间歇连通、拓扑结构变化频繁,网络中数据的传输只能依靠节点间机会性的传递,严重影响了这种以数据为中心的网络中的数据传输的性能。对目前车载传感器网络的研究现状进行了分析讨论,同时结合延迟容忍网络和机会网络思想,给出了车载传感器网络的研究方向。     

Ad hoc网络中一种新的路由选择算法*

提出了一种基于网络总时延最小的路由路径选择算法。该算法根据链路的时延来进行路由路径选择,从而达到网络总时延最小的目的。仿真表明,该算法可以动态调整网络路由路径,从而使网络总时延达到最小。     

WDM网络中实时组播的分布式路由与波长分配算法

在WDM网络中,由于每条链路上可用波长是动态变化的,在考虑波长转换延迟时间的条件下,实现实时组播连接的路由与波长分配是十分困难的。该文提出了一种用于建立实时组播连接的分布式路由与波长分配算法。该算法将路由与波长分配统一进行,大大减少连接的建立时间。组播路由算法以Prim最小生成树算法和K-度宽度优先搜索方法为基础,生成一棵满足给定延迟时限的最小成本树。波长分配使用最少波长转换和负载平衡策略。     

基于分布式信任管理的时延容忍网络数据转发方案

为解决时延容忍网络中恶意或自私节点严重影响网络性能的问题,提出一种基于分布式信任管理的时延容忍网络数据转发方案.通过计算节点信任值先滤除网络中的恶意节点,再执行数据转发行为.根据节点的转发行为以及它们的能量消耗信息计算出直接信任;邻居节点推荐的信息融合间接信任和推荐信誉计算出推荐信任;融合直接信任和推荐信任得到节点总体...     

干扰环境下面向延迟的骨干节点路由方法

由于参与节点多、移动性强,武器协同数据链一般采用分层的网络结构.战场环境下,己方通信经常会受到敌方干扰,而这将对武器协同数据链网络的一个很重要的性能指标--时延产生明显影响.另外,传统的只考虑下一跳延迟的路由方法并不能保证端到端延迟最小.针对这两个问题,提出了一种干扰环境下面向延迟的骨干节点路由方法和实现模型.该方法通过信息反馈、跨层的方法感知,利用临近节点的干扰信息和目的节点的端到端延迟信息,来为当前节点决定下一跳路由,实现最小端到端时延.仿真和数值结果表明,与几种典型路由协议相比,该方法具有更好的性能.     

An efficient anonymous authentication mechanism for delay tolerant networks

Security and privacy are crucial to the wide deployments of delay tolerant networks. Without security and privacy guarantees, people are reluctant to accept such a new network paradigm. To address the security and privacy issues in delay tolerant networks, in this paper, based on ID-based ring signatures and Merkle hash tree techniques, we present a new efficient anonymous authentication mechanism. The newly proposed mechanism not only achieves good security properties, including authentication, anonymity and confidentiality, but also has strong robustness and high efficiency.     

WSNs中满足时延要求的空洞抑制路由

满足数据传输时延要求是无线传感网络(Wireless Sensor Networks, WSNs)的关键问题。为了解决此问题,研究人员提出基于不同服务质量QoS的地理位置路由,但是这些路由并没有处理好路由空洞问题,也存在空洞边界拥塞问题,这些问题降低了数据包传递率。为此,提出基于时延要求的抑制路由空洞的WSNs地理位置路由(Delay-Guaranteed-based Suppressing Hole Geographic Routing, DG-SHGR)。DG-SHGR路由先检测路由空洞,然后为处于路由空洞周围的数据包定义雷区,使数据包的传输路径远离雷区。同时,依据数据包传输时延要求定义雷区尺寸,进而保证数据包的传输时延要求。实验数据表明,提出的DG-SHGR路由有效地提高了数据包传递率,并平衡负载     

A dynamic multicast tree based routing scheme without replication in delay tolerant networks

Delay tolerant networks (DTNs) are a special type of wireless mobile networks which may lack continuous network connectivity. Multicast is an important routing function that supports the distribution of data to a group of users: a service needed for many potential DTN applications. While multicasting in the Internet and in mobile ad hoc networks has been studied extensively, efficient multicasting in DTNs is a considerably different and challenging problem due to the probabilistic nature of contact among nodes. This paper aims to provide a non-replication multicasting scheme in DTNs while keeping the number of forwardings low. The address of each destination is not replicated, but is assigned to a particular node based on its contact rate level and active level. Our scheme is based on a dynamic multicast tree where each leaf node corresponds to a destination. Each tree branch is generated at a contact based on the compare–split rule proposed in this paper. The compare part determines when a new search branch is needed, and the split part decides how the destination set should be partitioned. When only one destination is left in the destination set, we use either wait (no further relay) or focus (with further relay) to reach the final destination. The effectiveness of our approach is verified through extensive simulations. Ratio-based-split performs best in the compare–split step, both in synthetic and real traces. Using the wait scheme can reduce the number of forwardings, while using the focus scheme can reduce the latency.