共查询到20条相似文献,搜索用时 15 毫秒
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多层卫星网络的拓扑结构具有明显的时变特征,难以提供持续且稳定的端到端路径,导致高效路由问题面临着巨大的挑战.将卫星网络设计为封闭的体系结构,采用强管理或调度式控制策略会导致其无法自由、高效地实现与其它系统的协同组网.基于IP的网络体系结构在应用于多层卫星网络时又存在路由效率不高的问题.基于命名数据网络NDN(Named Data Networking)体系结构,提出一种多层卫星网络分布式路由方法--SNDN(Satellite Named Data Networking).根据链路切换的周期性和可预知性,以时变图为建模工具,设计一个能自适应稠密和稀疏场景的路由算法来动态地计算时间相关的最快路径并附加为源路由信息,充分利用命名数据网络数据驱动的通信模式、数据包级的安全特性和逐跳转发的特点,由节点在包转发的过程中动态地完成转发表(FIB,Forwarding Information Base)和请求状态表(PIT,Pending Interest Table)的构建.可为面向未来空、天、地一体化协同组网的多层卫星网络路由研究提供一种新的思路.通过仿真实验及对比分析,验证了SNDN在路由效率和多播性能方面的优势. 相似文献
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无线自组织(Ad hoc)网络的应用环境要求其必须提供一定的服务质量(QoS)保证,然而,无线信道固有的特点及节点移动造成网络拓扑的频繁变化,使得在无线Ad hoc网络中支持QoS较困难。可以采用Ad hoc QoS多播(AQM)协议通过事先预约邻居节点以跟踪资源的有效性等措施来解决这一问题。通过考虑传输时延、丢失率、带宽要求、时延抖动、吞吐量等QoS指标,寻找满足特定QoS要求的路由,AQM协议可以明显地改善多播通信的性能。网络仿真结果表明AQM协议基本适合Adhoc网络。 相似文献
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描述了多约束QoS组播路由问题的网络模型,提出了一种解决该问题的改进的蚂蚁算法.该算法对网络进行预处理,生成初始解,并转化为网络的初始信息素分布,利用蚂蚁算法的正反馈特性调整信息量的分配,使之迅速收敛到问题的最优解.仿真表明,算法可以稳定地获得优于现有启发式算法的解,是一种有效的组播路由算法. 相似文献
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Distributed Utility Maximization for Network Coding Based Multicasting: A Shortest Path Approach 总被引:1,自引:0,他引:1
《Selected Areas in Communications, IEEE Journal on》2006,24(8):1475-1488
One central issue in practically deploying network coding is the adaptive and economic allocation of network resource. We cast this as an optimization, where the net-utility—the difference between a utility derived from the attainable multicast throughput and the total cost of resource provisioning—is maximized. By employing the MAX of flows characterization of the admissible rate region for multicasting, this paper gives a novel reformulation of the optimization problem, which has a separable structure. The Lagrangian relaxation method is applied to decompose the problem into subproblems involving one destination each. Our specific formulation of the primal problem results in two key properties. First, the resulting subproblem after decomposition amounts to the problem of finding a shortest path from the source to each destination. Second, assuming the net-utility function is strictly concave, our proposed method enables a near-optimal primal variable to be uniquely recovered from a near-optimal dual variable. A numerical robustness analysis of the primal recovery method is also conducted. For ill-conditioned problems that arise, for instance, when the cost functions are linear, we propose to use the proximal method, which solves a sequence of well-conditioned problems obtained from the original problem by adding quadratic regularization terms. Furthermore, the simulation results confirm the numerical robustness of the proposed algorithms. Finally, the proximal method and the dual subgradient method can be naturally extended to provide an effective solution for applications with multiple multicast sessions. 相似文献
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An algorithm for constructing and adaptively maintaining routing tables in communication networks is presented. The algorithm can be employed in message as well as circuit switching networks, uses distributed computation, provides routing tables that are loop-free for each destination at all times, adapts to changes in network flows, and is completely failsafe. The latter means that after arbitrary failures and additions, the network recovers in finite time in the sense of providing routing paths between all physically connected nodes. For each destination, the routes are independently updated by an update cycle triggered by the destination. 相似文献
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Previous distributed routing protocols in data-communication networks that achieve minimum average delay are extended to take into consideration topological changes in the network. 相似文献
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服务质量路由作为下一代IP互联网提供服务质量(QoS)控制的一种重要方案,如何提高其可扩展性和路由性能是有待解决的难题.本文提出了基于聚类的分布式预计算算法,以具有多种QoS参数的路由表预计算为目标,引入了支持QoS参数的扩展距离向量,通过网络中各个节点的分布式协同计算,大大降低了单个路由器的计算复杂度.文章分析了优势路径及其选取策略,给出了路由计算中优势路径聚集的聚类方法,实现了QoS路由表的高效聚集压缩.实验结果进一步验证了该算法具有计算量小和QoS路由性能高的优点,在QoS度量维数和网络规模方面均具有良好的可扩展性,并对域间算法研究提供了重要依据. 相似文献
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研究了在基于GMPLS的WDM网络中,当节点不具备波长变换能力并且配备有限个光收发器对时,如何为到达的业务请求建立标记交换路径(LSP)的问题。提出一种以跳数和带宽碎片要求为权重,合理分配带宽资源的新算法。仿真结果表明,该算法在保证用户业务可靠性要求的同时,能够更有效地提高全网资源的利用率,并大大降低网络阻塞的可能性。 相似文献
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研究了在基于GMPLS的WDM网络中,当节点不具备波长变换能力并且配备有限个光收发器对时,如何为到达的业务请求建立标记交换路径(LSP)的问题。提出一种以跳数和带宽碎片要求为权重,合理分配带宽资源的新算法。仿真结果表明,该算法在保证用户业务可靠性要求的同时,能够更有效地提高全网资源的利用率,并大大降低网络阻塞的可能性。 相似文献
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Mari Carmen Domingo 《Wireless Personal Communications》2011,57(4):607-627
The design of routing protocols for Underwater Wireless Sensor Networks (UWSNs) poses many challenges due to the intrinsic properties of underwater environments. In this paper we present DUCS (Distributed Underwater Clustering Scheme), a new GPS-free routing protocol that does not use flooding techniques, minimizes the proactive routing message exchange and uses data aggregation to eliminate redundant information. Besides, DUCS assumes random node mobility and compensates the high propagation delays of the underwater medium using a continually adjusted timing advance combined with guard time values to minimize data loss. The theoretical and simulation studies carried out demonstrate its effectiveness. 相似文献
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In this paper, a distributed multicast routing scheme is introduced for multi-layered satellite IP networks, which include GEO, MEO, and LEO layers. This scheme aims to minimize the total cost of multicast trees in the satellite network. Multicast trees are constructed and maintained in the dynamic satellite network topology in a distributed manner. Simulation results are provided to evaluate the performance of the new scheme in terms of end-to-end delay and multicast tree cost. 相似文献
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Recent demand for mobile telephone service has been growing rapidly while the electro-magnetic spectrum of frequencies allocated for this purpose remains limited. Any solution to the channel assignment problem is subject to this limitation, as well as the interference constraint between adjacent channels in the spectrum. Channel allocation schemes provide a flexible and efficient access to bandwidth in wireless and mobile communication systems. In this paper, we present an efficient distributed algorithm for dynamic channel allocation based upon mutual exclusion model, where the channels are grouped by the number of cells in a cluster and each group of channels cannot be shared concurrently within the cluster. We discuss the algorithm and prove its correctness. We also show that the algorithm requires at most (worst case) O(N
gN
n logN
n) messages, where N
g is the number of groups and N
n is the number of neighbors. This is compared to Choy's algorithm which requires O(N
g
2N
n), where N
g is the number of groups and N
n is the number of neighboring cells in the system. We report our algorithm's performance with several channel systems using different types of call arrival patterns. Our results indicate that significant low denial rate, low message complexity and low acquisition time can be obtained using our algorithm. 相似文献
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多点并行蚁群搜索在多限制动态组播中的应用研究 总被引:2,自引:0,他引:2
随着Internet的快速发展和商用化的提高,多媒体组播通信越来越引起人们的广泛关注。以往的研究成果大多是集中在固定的多点模型上,而许多服务是无法应用这种应用模型的。本文在充分研究以往组播通信的基础上,针对没有固定组成员的动态组播通信提出了运用蚁群算法进行并行寻路的算法模型。同时,为了加快蚁群算法的收敛速度,对该算法进行了一定的改进。仿真试验表明,该算法是一种有效的适应动态组成员的组播路由算法,具有一定的实用价值。 相似文献
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Opportunistic Routing (OR) involves mul-tiple forwarding candidates to relay packets by tak-ing advantage of the broadcast nature and multi-us-er diversity of a wireless medium. Compared with Traditional Routing (TR), OR is more suitable in the case of an unreliable wireless link and can evidently improve the end-to-end throughput of Wireless Mesh Networks (WMNs). In this paper, we focus on OR in Multi-Radio Multi-Channel WMNs (MRMC-WMNs). This problem has not been well examined and is considerably more challenging than the OR in single-radio wireless networks considered in the existing literature. First, we validate the advantage of OR in MRMC-WMNs. Second, we propose Low-complexity Channel Assignment for Opportunistic Routing ( LcCAOR ), which assigns channels to flows according to the interference state of every node. Third, we implement the LcCOAR in a fully distributed manner. The simulation result shows that compared with OR in Single-Radio Single-Channel WMNs (SRSC-WMNs), the proposed OR can sig-nificantly enhance the throughput to 87. 11% and 100.3% in grid and tree WMNs, respectively. 相似文献
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An algorithm is defined for establishing routing tables in the individual nodes of a data network. The routing table at a nodei specifies, for each other nodej , what fraction of the traffic destined for nodej should leave nodei on 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. 相似文献
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《Latin America Transactions, IEEE (Revista IEEE America Latina)》2007,5(8):616-625
In this paper, a general Combinatorial Ant System-based distributed routing algorithm modeled like a dynamic combinatorial optimization problem is presented. In the proposed algorithm, the solution space of the dynamic combinatorial optimization problem is mapped into the space where the ants will walk, and the transition probability and the pheromone update formula of the Ant System is defined according to the objective function of the communication problem. The general nature of the approach allows for the optimization of the routing function to be applied in different types of networks just changing the performance criteria to be optimized. In fact, we test and compare the performance of our routing algorithm against well-known routing schemes for wired and wireless networks, and show its superior performance in terms throughput, delay and energy efficiency. 相似文献