一种新型的Ad hoc QoS多播路由协议

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。     

容断网络中的组播路由算法研究

容断网络是一种新型的网络架构,主要用来解决频繁发生分离的网络场景中的数据通信.它为很多面临挑战的网络 (如星际网络、传感器网络、陆地移动网络等) 提供了互操作性,同时也可以满足特殊场合的应用,如军事战场、灾难营救、深空通信、边远地区的因特网接入等等.文章给出了一种新的容断网络中组播路由算法分类,并剖析了现有主要的组播路由算法.为容断网络组播的路由算法进一步研究提了一定的参考价值.     

基于蚂蚁算法的多约束QOS组播路由选择

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.     

多播同步协作的动态安全机制

分析了多播同步协作应用的安全问题,提出了一种比较实用的安全机制方案。并据此实现了一个多播视频会议的安全管理模块。     

A Failsafe Distributed Routing Protocol

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.     

A Failsafe Distributed Protocol for Minimum Delay Routing

Previous distributed routing protocols in data-communication networks that achieve minimum average delay are extended to take into consideration topological changes in the network.     

Distributed Utility Maximization for Network Coding Based Multicasting: A Shortest Path Approach

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.     

基于GMPLS的动态分布式WDM网状网路由选择算法研究

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。     

基于GMPLS的动态分布式WDM网状网路由选择算法研究

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。     

Ad Hoc网络组播路由ODMRP协议的改进

ODMRP组播协议非常适合于带宽限制大、移动性强和节点能量受限的Ad hoc网络.为了进一步提高该协议的性能,文中提出一种新的技术来增强其功效.增强ODMRP的主要目标有:(1)改进节点移动模式的适应性;(2)消除路由获得时延.最后仿真结果显示该改进协议比原协议在数据分发率和网络有效性等性能方面有很大改善.     

A Distributed Energy-Aware Routing Protocol for Underwater Wireless Sensor Networks

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.     

A Distributed Multicast Routing Scheme for Multi-Layered Satellite IP Networks

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.     

A Distributed Algorithm for Dynamic Channel Allocation

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.     

多点并行蚁群搜索在多限制动态组播中的应用研究

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。     

一种VLSI零偏差时钟线网布线算法

本文给出了一种时钟线网布线的新算法。算法基本上消化了时钟偏差,并使线网总线长得到了最小化。其关键在于：１在旋转定位的基础上,采用平衡合并的原则构造时钟树拓扑结构,并在合并过程中,保证点与弧之间的连续优化。２根据拓扑表,确定详细布线时的连线走向,从而对总线长作出了进一步的优化。实验结果表明,我们的算法是有效的,能够较好地用一大规模集成电路的时钟线网的布线。     

A General Combinatorial Ant System-based Distributed Routing Algorithm for Communication Networks

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.     

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.     

一种WDM疏导网络动态组播路由算法

对无波长变换能力的波分复用（WDM）疏导网络中的组播路由和波长分配（MRWA）问题进行了研究，提出了动态组播流量疏导算法（DMTGA）。这种算法根据当前网络资源使用情况，结合流量疏导和负载均衡，对链路权重进行动态配置，构建满足组播业务请求带宽需求的组播树。在不同的网络负载下对算法进行仿真，对比分析了DMTGA对业务请求接入率、平均网络资源利用率和全网负载分布的影响。     

一种无线自组织网络动态路由协议

介绍了一种基于稀疏树的无线自组织网络动态路由协议,该协议采用了稀疏树路径生成算法来减少路由更新的数据量并减少网络链路的冗余,采用增量更新来降低路由协议开销并降低对传输带宽的占用,支持单向信道,采用快速路径查找算法消除网络拓扑动态变化过程中的环路与无穷计数问题。仿真结果显示它具有收敛快,开销小等特性,能够较好地适应窄带无线通信环境的需要。     

物理损伤感知的多芯光纤网络动态路由资源分配方法

针对多芯光纤空分复用弹性光网络中物理损伤导致网络的频谱利用率低与带宽阻塞率高的问题,提出一种物理损伤感知的业务动态路由和资源分配方法.在路由阶段,设计考虑路径跳数、可用资源和路径上链路资源利用率的动态路径资源评判公式,选择负载均衡和资源占用较少的候选路径.在频谱和纤芯分配阶段,设计满足业务串扰和非线性阈值的纤芯和频谱分...