LEO星座中基于不完全信息的路由联盟博弈策略

针对LEO卫星网络在多跳转发数据包时流量分布不均问题,提出了一种基于不完全信息的最优收益路由联盟博弈算法.各节点协同联盟邻居节点,共同确定数据报文当前最优转发路径,从而分配和平衡节点间流量负载.仿真结果表明,与最短路径卫星路由DSP或智能路由TLR相比,本文算法的平均数据传输延迟降低了18.5%,节点流量负载均衡度提高了65.6%.     

Congestion management techniques for disruption‐tolerant satellite networks

Delay and disruption‐tolerant networks are becoming an appealing solution for extending Internet boundaries toward challenged environments where end‐to‐end connectivity cannot be guaranteed. In particular, satellite networks can take advantage of a priori trajectory estimations of nodes to make efficient routing decisions. Despite this knowledge is already used in routing schemes such as contact graph routing, it might derive in congestion problems because of capacity overbooking of forthcoming connections (contacts). In this work, we initially extend contact graph routing to provide enhanced congestion mitigation capabilities by taking advantage of the local traffic information available at each node. However, since satellite networks data generation is generally managed by a mission operation center, a global view of the traffic can also be exploited to further improve the latter scheme. As a result, we present a novel strategy to avoid congestion in predictable delay‐ and disruption‐tolerant network systems by means of individual contact plans. Finally, we evaluate and compare the performance improvement of these mechanisms in a typical low Earth orbit satellite constellation.     

一种无标度网络上的局部路由策略

提出了一种无标度（scale-free）网络上的局部路由策略。每个节点根据其当前负载与自身发送能力（设为等于节点度）的关系,自适应调整其接收邻居节点信息包的概率。此概率与每个节点度的α次方成正比,α是可自适应变化的偏好因子,由节点度以及负载联合决定。当节点负载小于发送能力时,增大其偏好因子;反之,则减小。这样使得整个网络业务量较小时,可以优先把业务转发往度较大的节点,从而更快到达目的地;而业务量较大时,度大以及度小节点的发送能力均能得到充分利用,从而提高了整个网络的业务承载能力。仿真结果表明,该策略有效地提高了网络容量,并且降低了网络中信息包的平均传输时延。     

基于蚁群优化的高性能拥塞控制路由机制

为了有效地解决偏远地理区域通信网络存在的网络拥塞严重、数据成功传输率低、数据冗余率高以及网络整体性能不佳等问题,通过考虑网络节点运动区域性特点,基于蚁群优化机制,设计出一种新型的容延容断网络 (DTN) 拥塞控制路由优化算法。该算法结合蚁群优化机制中的信息素因子,在同一对源、目的网络节点之间进行多次数据信息传输操作。在数据信息传输方向上,获取各个网络节点的中转跳数平均值,评估各个网络节点的中转价值;参考蚁群优化机制中的启发值因子,将网络节点的中转价值与剩余存储容量相关联,构成网络节点作为中转节点的评定参数,选取评定参数最大的网络节点完成其中转任务。实验表明：该算法有效控制了网络拥塞,提高了数据成功传输率,降低了数据信息冗余率,使网络整体性能得到进一步优化。     

Shortest Path Evaluation in Wireless Network Using Fuzzy Logic

Evaluation of the shortest path in a wireless network is to ensure the fast and guaranteed delivery of the data over the established wireless network. Most of the wireless protocols are using a shortest path evaluation technique which is based on the random weights assigned to the network nodes. This alone may not be sufficient to get the accurate shortest path for routing process. Most of the shortest path evaluation algorithms perform the blind search to find the shortest routes for routing, this eventually increase the complexity of the whole process itself. This article puts some light on facts of using real time estimated routing delay from source node to other nodes by broadcasting a “knock” message. And this delay is being used to evaluate the shortest path for routing using fuzzy logic. This process is enhanced with its improved inference engine model and furnished fuzzy crisp patterns to deploy the shortest routing path in real time wireless nodes.     

Development of a Real-Time Dynamic Weighting Method in Routing for Congestion Control: Application and Analysis

Congestion control issues have received consistent attention from several telecommunication researchers and practitioners for many years because network congestion often causes significant packet loss and delay problems. Although many suggested methods for these issues and problems can be available in telecommunication literature, there is room for improvement. This paper's primary objective is to propose a dynamic weighting method in routing to reduce congestion during peak hours by predicting incoming traffics and optimizing weights in the adjacency matrix of the routing table online. While changing weight values in the routing table, this method implicitly changes the routing path of many nodes through the congested node. As a result, the packet losses and delays can be decreased in used nodes. The main steps of this proposed framework are fourfold. First, the candidate weighing list is calculated based on the routing table of the congested node. Second, a proposed auto-adaptive framework (AAF) is used to predict congestion levels and apply the weighing list in the network node. Third, the evaluation of network congestion is then performed by the probability of packet losses due to overflowing buffers. Finally, the case study results demonstrate that the proposed AAF framework can significantly reduce network congestion.

     

基于流量预测的物联网卫星节点动态缓存分配路由策略

针对低轨物联网卫星系统的路由问题,提出了基于流量预测的物联网卫星节点动态缓存分配路由策略。首先,分析低轨卫星覆盖区域内业务分布的时空特性,提出了端到端流量预测方法。然后,根据流量预测结果,提出了动态缓存分配路由策略。卫星节点通过对星间链路的流量负载进行周期性监测,动态分配与邻居节点间各条星间链路的缓存资源,分为初始化和系统运行2个阶段。同时,提出了节点拥塞时的业务分流及数据分组转发策略,通过比较排队时延和转发时延的大小,决定数据分组是否需要进行重路由。仿真结果表明,所提路由策略有效地降低了分组丢失率及平均端到端时延,改善了业务在全网的分布情况。     

A Minimum Delay Routing Algorithm Using Distributed Computation

An algorithm is defined for establishing routing tables in the individual nodes of a data network. The routing table at a nodeispecifies, for each other nodej, what fraction of the traffic destined for nodejshould leave nodeion each of the links emanating from nodei. The algorithm is applied independently at each node and successively updates the routing table at that node based on information communicated between adjacent nodes about the marginal delay to each destination. For stationary input traffic statistics, the average delay per message through the network converges, with successive updates of the routing tables, to the minimum average delay over all routing assignments. The algorithm has the additional property that the traffic to each destination is guaranteed to be loop free at each iteration of the algorithm. In addition, a new global convergence theorem for noncontinuous iteration algorithms is developed.     

Proactive multipath routing with a predictive mechanism in software‐defined networks

With the growth of network traffic volume, link congestion cannot be avoided efficiently with conventional routing protocols. By utilizing the single shortest‐path routing algorithm from link state advertisement information, standard routing protocols lack of global awareness and are difficult to be modified in a traditional network environment. Recently, software‐defined network (SDN) provided innovative architecture for researchers to program their own network protocols. With SDN, we can divert heavy traffic to multiple paths in order to resolve link congestion. Furthermore, certain network traffics come in periodic fashion such as peak hours at working days so that we can leverage forecasting for resource management to improve its performance. In this paper, we propose a proactive multipath routing with a predictive mechanism (PMRP) to achieve high‐performance congestion resolution. PMRP has two main concepts: (a) a proactive mechanism where PMRP deploys M/M/1 queue and traffic statistics to simulate weighted delay for possible combinations of multipaths placement of all subnet pairs, and leverage genetic algorithm for accelerating selection of optimized solution, and (b) a predictive mechanism whereby PMRP uses exponential smoothing for demand traffic volumes and variance predictions. Experimental results show a 49% reduction in average delay as compared with single shortest routing, and a 16% reduction in average delay compared with utilization & topology‐aware multipath routing (UTAMP). With the predictive mechanism, PMRP can decrease an additional 20% average delay. Furthermore, PMRP reduces 93% of flow table usage on average as compared with UTAMP.     

Gateway load balancing using multiple QoS parameters in a hybrid MANET

A Mobile ad hoc network (MANET) is a self configurable wireless network in which mobile nodes communicate with each other in a multihop fashion without any pre-installed infrastructure. A MANET can be considered to be a standalone network. To enhance the connectivity of a MANET it can be connected to the fixed network, thus forming a heterogeneous network. The integration of MANET and the Internet is called a hybrid MANET which is facilitated by special nodes called Internet gateway nodes. Load balancing among gateways is a challenging task when a MANET is connected to Internet. Gateway nodes with higher loads will lead to disconnected networks and depletes the node’s resources which include their batteries, memory and bandwidth quickly. Gateway selection based on the shortest path may increase traffic concentration on one particular gateway which leads to congestion and increases delay in the network. In this paper a QoS based load balancing mechanism has been proposed among multiple gateway nodes that provide communication between mobile nodes and fixed nodes in the Internet to select lightly loaded gateways so that more packets will be delivered to the fixed host in the Internet. The proposed QoS based scheme selects four QoS parameters that are (1) connecting degree, (2) interface queue length, (3) routing table entries and (4) hop count. A weight based method is used to select the gateway which combines all four QoS metrics. Simulation results demonstrate that when compared with individual parameter, the average ETE delay, queue size and traffic load of gateway generated by proposed algorithm is decreased by 17, 25 and 15 % respectively and when compared with existing schemes, the average ETE delay, queue size and traffic load of gateway is decreased by 25, 25 and 16 % respectively.     

Dynamic power allocation and routing for time-varying wireless networks

We consider dynamic routing and power allocation for a wireless network with time-varying channels. The network consists of power constrained nodes that transmit over wireless links with adaptive transmission rates. Packets randomly enter the system at each node and wait in output queues to be transmitted through the network to their destinations. We establish the capacity region of all rate matrices (/spl lambda//sub ij/) that the system can stably support-where /spl lambda//sub ij/ represents the rate of traffic originating at node i and destined for node j. A joint routing and power allocation policy is developed that stabilizes the system and provides bounded average delay guarantees whenever the input rates are within this capacity region. Such performance holds for general arrival and channel state processes, even if these processes are unknown to the network controller. We then apply this control algorithm to an ad hoc wireless network, where channel variations are due to user mobility. Centralized and decentralized implementations are compared, and the stability region of the decentralized algorithm is shown to contain that of the mobile relay strategy developed by Grossglauser and Tse (2002).     

A Basic Dynamic Routing Problem and Diffusion

Diffusion theory has sometimes been successful in providing excellent approximate solutions to difficult queueing problems. Here we explore whether such methods can be used to analyze a basic dynamic routing strategy associated with a single idealized node in a data network. We analyze a dynamic routing policy where messages, or packets, that arrive at a certain node are routed to leave the node on the link having the shorter queue. In the model, message or packet arrivals are Poisson and the service time is exponentially distributed. We explore a heavy traffic diffusion method and we also discuss the limitations of an ad hoc approach to applying diffusion. For a node withKoutgoing queues we find, under the assumption of heavy traffic, the optimum dynamic strategy, in the sense of minimizing the average delay. When this optimum dynamic strategy is compared to a static strategy where the outgoing traffic is split among theKqueues, we find that the average delay for the dynamic system is better by a factor ofK.     

A Unified Approach to Congestion Control and Node-Based Multipath Routing

The paper considers a TCP/IP-style network with flow control at end-systems based on congestion feedback and routing decisions at network nodes on a per-destination basis. The main generalization with respect to standard IP is to allow routers to split their traffic in a controlled way between the outgoing links. We formulate global optimization criteria, combining those used in the congestion control and traffic engineering, and propose decentralized controllers at sources and routers to reach these optimal points, based on congestion price feedback. We first consider adapting the traffic splits at routers to follow the negative price gradient; we prove this is globally stabilizing when combined with primal congestion control, but can exhibit oscillations in the case of dual congestion control. We then propose an alternative anticipatory control of routing, proving its stability for the case of dual congestion control. We present a concrete implementation of such algorithms, based on queueing delay as congestion price. We use TCP-FAST for congestion control and develop a multipath variant of the distance vector routing protocol RIP. We demonstrate through ns2-simulations the collective behavior of the system, in particular that it reaches the desired equilibrium points.     

Integrating machine learning in ad hoc routing: A wireless adaptive routing protocol

The nodes in a wireless ad hoc network act as routers in a self‐configuring network without infrastructure. An application running on the nodes in the ad hoc network may require that intermediate nodes act as routers, receiving and forwarding data packets to other nodes to overcome the limitations of noise, router congestion and limited transmission power. In existing routing protocols, the ‘self‐configuring’ aspects of network construction have generally been limited to the construction of routes that minimize the number of intermediate nodes on a route while ignoring the effects that the resulting traffic has on the overall communication capacity of the network. This paper presents a context‐aware routing metric that factors the effects of environmental noise and router congestion into a single time‐based metric, and further presents a new cross‐layer routing protocol, called Warp‐5 (Wireless Adaptive Routing Protocol, Version 5), that uses the new metric to make better routing decisions in heterogeneous network systems. Simulation results for Warp‐5 are presented and compared to the existing, well‐known AODV (Ad hoc On‐Demand Distance Vector) routing protocol and the reinforcement‐learning based routing protocol, Q‐routing. The results show Warp‐5 to be superior to shortest path routing protocols and Q‐routing for preventing router congestion and packet loss due to noise. Copyright © 2011 John Wiley & Sons, Ltd.     

Adaptive reliable and congestion control routing protocol for MANET

In mobile ad hoc networks (MANETs), the packet loss can be caused either by link failure or by node failure. Moreover, the techniques for selecting the bypass route and avoiding congestion in the bypass route are rarely handled. To overcome these, in this paper, we propose an adaptive reliable and congestion control routing protocol to resolve congestion and route errors using bypass route selection in MANETs. The multiple paths are constructed. Among which, the shortest paths are found for efficient data transmission. The congestion is detected on the basis of utilization and capacity of link and paths. When a source node detects congestion on a link along the path, it distributes traffic over alternative paths by considering the path availability threshold and using a traffic splitting function. If a node cannot resolve the congestion, it signals its neighbors using the congestion indication bit. By using simulation, we show that that the proposed protocol is reliable and achieves more throughput with reduced packet drops and overhead.     

Design of logical topologies for wavelength-routed optical networks

The problem of designing a logical topology over a wavelength-routed all-optical network (AON) physical topology is studied. The physical topology consists of the nodes and fiber links in the network. On an AON physical topology, we can set up lightpaths between pairs of nodes, where a lightpath represents a direct optical connection without any intermediate electronics. The set of lightpaths along with the nodes constitutes the logical topology. For a given network physical topology and traffic pattern, our objective is to design the logical topology and the routing algorithm so as to minimize the network congestion while constraining the average delay seen by a source-destination pair and the amount of processing required at the nodes (degree of the logical topology). Ignoring the delay constraints can result in fairly convoluted logical topologies with very long delays. On the other hand, in all our examples, imposing it results in a minimal increase in congestion. While the number of wavelengths required to imbed the resulting logical topology on the physical all optical topology is also a constraint in general, we find that in many cases of interest this number can be quite small. We formulate the combined logical topology design and routing problem described above as a mixed integer linear programming problem which we then solve for a number of cases of a six-node network. This programming problem is split into two subproblems: logical topology design, and routing. We then compare the performance of several heuristic topology design algorithms against that of randomly generated topologies, as well as lower bounds     

The New Routing Algorithm for the ARPANET

The new ARPANET routing algorithm is an improvement over the old procedure in that it uses fewer network resources, operates on more realistic estimates of network conditions, reacts faster to important network changes, and does not suffer from long-term loops or oscillations. In the new procedure, each node in the network maintains a database describing the complete network topology and the delays on all lines, and uses the database describing the network to generate a tree representing the minimum delay paths from a given root node to every other network node. Because the traffic in the network can be quite variable, each node periodically measures the delays along its outgoing lines and forwards this information to all other nodes. The delay information propagates quickly through the network so that all nodes can update their databases and continue to route traffic in a consistent and efficient manner. An extensive series of tests were conducted on the ARPANET, showing that line overhead and CPU overhead are both less than two percent, most nodes learn of an update within 100 ms, and the algorithm detects congestion and routes packets around congested areas.     

Design and Performance Analysis of a Proxy-Based Indirect Routing Scheme in Ad Hoc Wireless Networks

The majority of existing ad hoc network routing protocols has a tendency to use the shortest single path from a source to a destination. However, in constantly changing topologies such as those in mobile ad hoc wireless networks, the shortest single path is not only unreliable for reachability but also unsuitable for traffic load equilibrium. In order to improve routing performance and make optimum use of the limited resources, the congestion must first be relieved as much as possible and the routing path be made available at all times. In this paper, we propose a novel scheme, called the Applicative Indirect Routing (AIR), to control network traffic congestion and refine route availability by coping with unreliable links quickly. The proposed scheme, acting as a proactive routing protocol, utilizes additional information about the neighbors shared by the sender and the receiver to find an alternative for the original path with unreliable links. The additional bandwidth usage in AIR to obtain the information about shared neighbors (defined as proxy candidates) is so minimal that the bandwidth availability for user data traffic is not significantly affected. Extensive simulation experiments show that compared with a conventional proactive protocol, namely Destination-Sequenced Distance Vector (DSDV), the AIR scheme leads to a much improved system performance in terms of packet delivery ratio, average end-to-end packet delay, and network reliability. We further show that, in terms of packet delivery ratio, AIR is also a competitive protocol compared with such reactive protocols as Ad hoc On Demand Distance Vector (AODV) and Dynamic Source Routing (DSR).     

弹性光网络中基于安全性感知的差异化虚拟光网络的映射策略

针对虚拟环境下底层网络中光纤的概率性故障,传统的100%保护至少需要配置一条保护路径,造成资源冗余度高和虚拟网络请求接受率低的问题,该文提出一种基于安全性感知的差异化虚拟光网络的映射(SA-DVNM)策略,在链路发生故障时为差异化虚拟网络请求提供安全保证。在SA-DVNM策略中,设计了一个综合考虑物理节点对之间跳数和相邻带宽大小的节点权重式避免链路映射过长,并提出路径频谱资源使用均衡的链路映射机制,最小化瓶颈链路的数量。当单路径传输失败时,SA-DVNM策略设计允许路径分割的资源分配机制,为保障时延敏感业务的安全性,SA-DVNM策略在路由选择中设计了基于时延差优化的多路径路由频谱分配方法。仿真结果表明该文所提策略在概率故障环境中能够降低带宽阻塞率,提高频谱资源利用率和虚拟光网络接受率。

     

移动Ad hoc网络多目标路由协议的仿真分析

传统的单目标路由协议很难完全满足Ad hoc网络业务量增加的需求.多目标路由协议在传输过程中可以构建最佳的多目标路由树,链路带宽消耗较小,节点的处理较少,分组交付时延较短,从而降低了通信开销.对Adhoc网络中的典型多目标路由协议MAODV和ODMRP协议进行性能分析,并用仿真工具NS2对它们进行仿真.仿真结果表明：多目标路由协议只有采用更加合理的算法和策略才能使其更稳定和更高效.