间断连接无线互联网络中路由问题的动态规划方法

在间断连接无线互联网络中，由于自然干扰或人为因素影响，节点之间无线链路通常在时间上具有间断特性，这就为间断连接无线互联网络的选路问题提出了新的挑战。丈章在链路统计特性的基础上，重点分析了运用动态规划方法求解该问题的基本思路。并且给出了该方法的基本方程，从理论上分析了该方法的正确性和有效性。     

分组交换网分布式自适应链路选路算法及其初始解法

本文从分组交换网的网路时延对链路路由变量为凸函数这一性质出发,应用拉格朗日乘子法证明了仅当网中任一节点到相邻节点的边际链路时延相等时才有可能使网路时延达到最佳,从而从理论上统一了链路选路算法。本文所提出的“容量压缩”算法是自适应链路选路算法获得初始解的一个有效的启发式算法,并与最小边际链路时延算法和自动机调整链路路由变量算法相结合,经实例计算,其结果优于流量偏差算法,具有一定的实用价值。     

一种新型IP数据链网络路由算法模型

针对无线数据链网络,提出了一种新型的基于分层结构的IP路由算法模型,满足至少3种异构数据链网络的集成要求.仿真结果表明,该模型可有效支撑基于链路带宽、传输时延、链路质量等多种QoS的路由算法设计,为无线数据链网络层IP路由协议和算法设计提供了理论框架和实现指导.     

自动交换光网络SCN性能和可靠性规划

自动交换光网络连接的恢复性能、可靠性依赖于信令通信网络(SCN)的性能和可靠性，本文分析了SCN的网络性能、端对端时延特性和可靠性，得出影响自动交换光网络路由信令性能和可靠性的一些关键因素，提出了基于连接恢复性能的SCN规划方案和基于单链路失效无故障恢复的SCN和网络规划方案，性能规划方案可估计端对端连接恢复的时间范围，可靠性规划方案可解决单链路失效连接无故障恢复问题，并能提高路由广播效率．     

Hadoop平台下一种改进蚂蚁算法的QoS路由研究

随着未来云计算的发展,各种云服务的应用将需要更高的网络性能。链路拥塞导致的数据包传输时延或数据包丢弃使得网络无法保障业务的QoS。目前普遍使用的链路状态路由算法不具有拥塞响应机制。本文通过在拥塞节点间发送连接蚂蚁寻找新路由来解决拥塞问题。NS2仿真结果表明,该算法能加快新的路由搜索,满足QoS的需求,并有效控制丢包率,时延等性能。     

随机间断连接无线互联网路由研究

随机间断连接无线互联网是当前的无线通信的研究热点之一。传统的路由算法不适用于这种网络,因此路由技术是一个研究的重点问题。在介绍了传统DSR路由和随机性间断连接无线互联网路由Epidemic算法的基础上,分析了比较了DSR和Epidemic的优缺点。     

一种高能效低时延的LLN路由修复算法

由于低功耗有损网络(LLN)中无线链路的不稳定性和有损性,外部环境的干扰极易导致网络出现故障,从而严重影响网络性能,而LLN网络中现有路由修复算法存在控制开销冗余和修复时延较大等问题。为此,提出了一种高能效低时延的LLN路由修复算法(EELDR-RPL)。该算法通过采用“零额外控制开销通告链路故障及邻居节点信息”机制,使得链路故障节点的子节点能够及时获知链路故障以及链路故障节点的邻居情况;通过采用“自适应调整节点网络深度值”机制,使得链路故障节点能够快速地重新接入网络;通过采用“链路故障节点子节点自适应切换”机制,能够达到优化网络拓扑的目的。仿真结果表明,与现有路由修复算法相比,EELDR-RPL算法能够有效地降低路由修复时延和减少控制开销。     

基于链路效用的3D-VANET可靠路由算法

针对三维车载自组织网络中,高速移动的车辆节点和复杂多变的链路状态导致车辆间通信链路不稳定的问题,通过引入软件定义网络技术实时获取网络状态并预测其变化过程,构建时-空演化图模型,并定义链路效用指标量化无线链路性能,然后建立基于链路效用的加权时-空演化图模型,最后将路由问题转化为多属性决策问题,设计基于链路效用的可靠路由算法.仿真结果表明,相对现有四种路由算法,本文所提路由算法在数据包传输率、端到端时延和路由负载率方面,性能均有明显提升.     

基于跨层设计的AODV路由算法研究

为了提高移动Ad Hoc网络中AODV路由算法的性能,提出了一种基于两跳邻居信息的高效AODV路由算法-TNAODV,文中采用两跳邻居信息机制,减少了建立路由所耗的时间;同时通过在网络层、MAC层与物理层三层之间的跨层协同,实现了及时的感知链路的连接状态,减少了因链路断裂而增加的路由开销。性能分析和仿真结果均表明,该路由算法在端到端时延、成功率等性能优于经典的AODV路由算法。     

无线传感器网络自适应并发多路由算法

无线传感器网络地理位置路由算法需要克服本地最小化现象.已有的算法均以"右手规则"为基础来克服这一现象,但是,"右手规则"会损失链路且难以在路由过程中动态调整所选路由,对自适应多路由选择不利.通过深入分析本地最小化现象,发现合理限定贪心算法的选路区域可以克服本地最小化现象,由此提出Clockwise Rule,该规则不损失链路,可动态调整所选路由,耗费低.在此基础上,提出了自适应并发多路由算法APMR(Adaptive Parallel Multi-path Routing).算法是分布式的,可在任意中继节点处动态调整路由策略,优化路由过程.仿真结果表明APMR算法对网络性能有很好的改善.     

Primate-inspired adaptive routing in intermittently connected mobile communication systems

An intermittently connected mobile ad hoc network is a special type of wireless mobile network without fully connected path between the source and destination most of the time. In some related works on mobility models, the missing realism of mobility model has been discussed. However, very few routing protocols based on realistic mobility models have been proposed so far. In this paper, we present a primate-inspired mobility model for intermittently connected mobile networks. Such a mobility model can represent and reflect the mobile features of humans. Traditional routing schemes in intermittently connected mobile networks fail to integrate the mobility model with routing strategy to fully utilize the mobility features. To overcome such a drawback, we propose a new routing scheme called primate-inspired adaptive routing protocol (PARP), which can utilize the features of the primate mobility to assist routing. Furthermore, our proposed protocol can determine the number of message copies and the routing strategy based on the walking length of the mobility model. The predictions of the walking lengths are implemented by a particle filter based algorithm. Our results demonstrate that PARP can achieve a better performance than a few typical routing protocols for intermittently connected mobile ad hoc networks.     

Routing in Delay-Tolerant Networks Comprising Heterogeneous Node Populations

Communication networks are traditionally assumed to be connected. However, emerging wireless applications such as vehicular networks, pocket-switched networks, etc., coupled with volatile links, node mobility, and power outages, will require the network to operate despite frequent disconnections. To this end, opportunistic routing techniques have been proposed, where a node may store-and-carry a message for some time, until a new forwarding opportunity arises. Although a number of such algorithms exist, most focus on relatively homogeneous settings of nodes. However, in many envisioned applications, participating nodes might include handhelds, vehicles, sensors, etc. These various "classes” have diverse characteristics and mobility patterns, and will contribute quite differently to the routing process. In this paper, we address the problem of routing in intermittently connected wireless networks comprising multiple classes of nodes. We show that proposed solutions, which perform well in homogeneous scenarios, are not as competent in this setting. To this end, we propose a class of routing schemes that can identify the nodes of "highest utility” for routing, improving the delay and delivery ratio by four to five times. Additionally, we propose an analytical framework based on fluid models that can be used to analyze the performance of various opportunistic routing strategies, in heterogeneous settings.     

Routing for disruption tolerant networks: taxonomy and design

Communication networks, whether they are wired or wireless, have traditionally been assumed to be connected at least most of the time. However, emerging applications such as emergency response, special operations, smart environments, VANETs, etc. coupled with node heterogeneity and volatile links (e.g. due to wireless propagation phenomena and node mobility) will likely change the typical conditions under which networks operate. In fact, in such scenarios, networks may be mostly disconnected, i.e., most of the time, end-to-end paths connecting every node pair do not exist. To cope with frequent, long-lived disconnections, opportunistic routing techniques have been proposed in which, at every hop, a node decides whether it should forward or store-and-carry a message. Despite a growing number of such proposals, there still exists little consensus on the most suitable routing algorithm(s) in this context. One of the reasons is the large diversity of emerging wireless applications and networks exhibiting such “episodic” connectivity. These networks often have very different characteristics and requirements, making it very difficult, if not impossible, to design a routing solution that fits all. In this paper, we first break up existing routing strategies into a small number of common and tunable routing modules (e.g. message replication, coding, etc.), and then show how and when a given routing module should be used, depending on the set of network characteristics exhibited by the wireless application. We further attempt to create a taxonomy for intermittently connected networks. We try to identify generic network characteristics that are relevant to the routing process (e.g., network density, node heterogeneity, mobility patterns) and dissect different “challenged” wireless networks or applications based on these characteristics. Our goal is to identify a set of useful design guidelines that will enable one to choose an appropriate routing protocol for the application or network in hand. Finally, to demonstrate the utility of our approach, we take up some case studies of challenged wireless networks, and validate some of our routing design principles using simulations.     

Experimental Evaluation of Routing Schemes for Intermittently Connected Wireless Mobile Networks

Several routing schemes have been proposed for intermittently connected wireless mobile networks. The effectiveness of these routing schemes is mostly evaluated using the metrics: messages delivered, message traffic and delay suffered by delivered messages. These metrics provide very limited evaluation of routing schemes. Even very simple and well known attributes like time and space complexity of routing schemes were not measured for evaluating the quality and applicability of routing schemes. Therefore, many significant aspects such as, resource utilization, efficiency in terms of space and time, quality of service parameters and security aspect etc. of routing schemes get overlooked. In this paper, we present the results of experimental evaluation, through simulation, of routing schemes for intermittently connected wireless mobile networks such as Delay Tolerant Network. We evaluated four routing schemes, based on different principles, namely First contact, Epidemic, Spray and wait and Dynamic Social Grouping, on parameters, such as, resource utilization, efficiency, performance and security. We found Spray and wait routing scheme performed better than others, both in terms of resource utilization and efficiency (time and space).     

基于流的无线网络编码

针对无线链路的不可靠性和物理层的广播特性,将网络编码与无线网络相结合,提出一种基于流的无线网络编码算法——FNC。该算法在先验参考路径的基础上,充分利用每个节点处的路由表项,探测编码机会,在有编码机会的节点对满足编码条件的数据流进行网络编码,达到提高网络吞吐量的目的。仿真结果表明：FNC有效提高了整个网络的吞吐量,改善了网络性能。     

Impact of Bloom Filter on Infection Rate in Epidemic Forwarding for ICNs

Mobile ad hoc routing protocols fails in intermittently connected networks (ICN) (i.e. characterized by short-range communication and absence of connected path from source to destination). However, Epidemic routing techniques ensures eventual message delivery from source to destination even where there is never a connected path or when a network partition exists at the origin of message. Epidemic Routing uses random pair-wise messages exchanges between nodes with goals to maximize message delivery rate, minimize message latency, and the total resources consumed in message delivery. Epidemic routing uses summary vector to avoid useless transmission and redundancy. Further,to make summery vector efficient, epidemic routing can use bloom filter to significantly reduce the useless transmissions associated with the summary vector. However, the challenge for epidemic routing remains opens is to optimal design of summary vector size for finite buffer while keeping the benefits of infinite buffer space. This paper proposes an improved scheme of Bloom filter (named it modified bloom filter MBLF), which is tailored according to epidemic routing. We performed simulation to support our clam and observed that delivery ratio of MBLF with epidemic routing is 19 % higher then the traditional bloom filter. In this paper, we have proposed a bloom filter based epidemic forwarding for ICNs.     

Weighted Steiner Connected Dominating Set and its Application to Multicast Routing in Wireless MANETs

In this paper, we first propose three centralized learning automata-based heuristic algorithms for approximating a near optimal solution to the minimum weight Steiner connected dominating set (WSCDS) problem. Finding the Steiner connected dominating set of the network graph is a promising approach for multicast routing in wireless ad-hoc networks. Therefore, we present a distributed implementation of the last approximation algorithm proposed in this paper (Algorithm III) for multicast routing in wireless mobile ad-hoc networks. The proposed WSCDS algorithms are compared with the well-known existing algorithms and the obtained results show that Algorithm III outperforms the others both in terms of the dominating set size and running time. Our simulation experiments also show the superiority of the proposed multicast routing algorithm over the best previous methods in terms of the packet delivery ratio, multicast route lifetime, and end-to-end delay.     

High throughput route selection in multi-rate wireless mesh networks

Most existing Ad-hoc routing protocols use the shortest path algorithm with a hop count metric to select paths. It is appropriate in single-rate wireless networks, but has a tendency to select paths containing long-distance links that have low data rates and reduced reliability in multi-rate networks. This article introduces a high throughput routing algorithm utilizing the multi-rate capability and some mesh characteristics in wireless fidelity （WiFi） mesh networks. It uses the medium access control （MAC） transmission time as the routing metric, which is estimated by the information passed up from the physical layer. When the proposed algorithm is adopted, the Ad-hoc on-demand distance vector （AODV） routing can be improved as high throughput AODV （HT-AODV）. Simulation results show that HT-AODV is capable of establishing a route that has high data-rate, short end-to-end delay and great network throughput.     

A Dominating-Set-Based Routing Scheme in Ad Hoc Wireless Networks

Efficient routing among a set of mobile hosts (also called nodes) is one of the most important functions in ad hoc wireless networks. Routing based on a connected dominating set is a promising approach, where the searching space for a route is reduced to nodes in the set. A set is dominating if all the nodes in the system are either in the set or neighbors of nodes in the set. In this paper, we propose a simple and efficient distributed algorithm for calculating connected dominating set in ad hoc wireless networks, where connections of nodes are determined by their geographical distances. We also propose an update/recalculation algorithm for the connected dominating set when the topology of the ad hoc wireless network changes dynamically. Our simulation results show that the proposed approach outperforms a classical algorithm in terms of finding a small connected dominating set and doing so quickly. Our approach can be potentially used in designing efficient routing algorithms based on a connected dominating set.