A shortest path routing algorithm for incomplete WK-recursivenetworks

The WK-recursive networks own two structural advantages: expansibility and equal degree. A network is expansible if no changes to node configuration and link connection are necessary when it is expanded, and of equal degree if its nodes have the same degree no matter what the size is. However, the number of nodes contained in a WK-recursive network is restricted to d^t, where d>1 is the size of the basic building block and t⩾1 is the level of expansion. The incomplete WK-recursive networks, which were proposed to relieve this restriction, are allowed to contain an arbitrary number of basic building blocks, while presenting the advantages of the WK-recursive networks. Designing shortest-path routing algorithms for incomplete networks is in general more difficult than for complete networks. The reason is that most incomplete networks lack a unified representation. One of the contributions of this paper is to demonstrate a useful representation, i.e., the multistage graph representation, for the incomplete WK-recursive networks. On the basis of it, a shortest-path routing algorithm is then proposed. With O(d·t) time preprocessing, this algorithm takes O(t) time for each intermediate node to determine the next node along the shortest path     

基于空洞模型的地理位置路由改进算法研究

针对现有WSN中地理位置路由遇路由空洞后会产生冗余路由的问题,提出一种基于感知空洞形状的分段贪婪路由(Easy Modeling Greedy Routing,EMGR)算法。EMGR引入虚拟坐标概念,利用空洞边界探测包收集空洞边界节点信息,将其映射到虚拟坐标系中;根据空洞边界节点在虚拟坐标系的不同分布,定义凹、凸域来概括路由空洞形状;根据不同的空洞形状找到合适的中转节点,采用分段贪婪路由方式传输数据。仿真实验结果表明,相较于GPSR算法,EMGR算法产生的路由跳数减少了35%,网络能耗低,路径扩张率和网络时延小。     

Fault-tolerant wormhole routing for hypercube networks

We present an adaptive fault-tolerant wormhole routing algorithm for hypercubes by using 3 virtual networks. The routing algorithm can tolerate at least n−1 faulty nodes and can route a message via a path of length no more than the shortest path plus four. Previous algorithms which achieve the same fault tolerant ability need 5 virtual networks. Simulation results are also given in this paper.     

利用匿名通信的匿名电子拍卖协议

为了保护电子拍卖中竞拍者的身份隐私,提出了一个基于匿名通信的匿名电子拍卖协议.该协议在密封式拍卖方式的基础上,采用匿名通信模型进行通信.在整个通信过程中,竞拍者随机选取网络中的一个节点进行数据的转发,然后该中转节点再以概率Pf将数据发送给下一个中转节点或是以概率1-Pf将数据发送给拍卖服务器,下一个中转节点重复该中转节点的过程,直到最后一个中转节点将数据发送给拍卖服务器.在发送数据的过程中,使用AES算法和RSA算法分别对消息和密钥进行混合加密解密操作.数据经过多次转发最终到达拍卖服务器.拍卖服务器、任意的中转节点和攻击者都不可能获取竞拍者的身份和位置信息.任意的中转节点和攻击者都不可能获取竞拍者的竞标信息.相比较Crowds、Tor以及其改进的方案,本方案在通信过程中不需要提前建立链路,避免了路由路径上节点建好链路后节点故障而引起的通信失败.通信过程中所有节点都是对等的,并且整个路由路径中不依赖于某些特殊节点,因此该协议实现了网络流量的负载均衡且大大提高了网络的健壮性.理论分析和实验结果表明,该协议不仅稳定性较好,而且可以在较低的通信和计算代价下获得较好的匿名效果.     

基于历史相遇间隔的机会网络路由协议

针对大多数机会网络路由协议在寻找端到端通信链路时不能很好地抓住节点社会性质的问题,提出一种基于历史相遇间隔(HICR) 协议的路由算法。HICR协议利用社会关系的特点,根据节点之间的历史相遇间隔判断它们的亲密程度,转发消息给离目的节点更亲近的节点,使得消息朝更靠近目的节点方向发送。仿真结果表明,该HICR协议在网络资源有限的的情况下,与Epidemic协议和Prophet协议相比,能获得更高的消息交付率。     

A theory of deadlock-free adaptive multicast routing in wormholenetworks

A theory for the design of deadlock-free adaptive routing algorithms for wormhole networks, proposed by the author (1991, 1993), supplies sufficient conditions for an adaptive routing algorithm to be deadlock-free, even when there are cyclic dependencies between channels. Also, two design methodologies were proposed. Multicast communication refers to the delivery of the same message from one source node to an arbitrary number of destination nodes. A tree-like routing scheme is not suitable for hardware-supported multicast in wormhole networks because it produces many headers for each message, drastically increasing the probability of a message being blocked. A path-based multicast routing model was proposed by Lin and Ni (1991) for multicomputers with 2D-mesh and hypercube topologies. In this model, messages are not replicated at intermediate nodes. This paper develops the theoretical background for the design of deadlock-free adaptive multicast routing algorithms. This theory is valid for wormhole networks using the path-based routing model. It is also valid when messages with a single destination and multiple destinations are mixed together. The new channel dependencies produced by messages with several destinations are studied. Also, two theorems are proposed, developing conditions to verify that an adaptive multicast routing algorithm is deadlock-free, even when there are cyclic dependencies between channels. As an example, the multicast routing algorithms of Lin and Ni are extended, so that they can take advantage of the alternative paths offered by the network     

一种抗干扰半静态分簇路由算法

针对无线传感器网络( WSNs)分簇路由算法中的能量洞、热点和抗干扰问题,设计一种抗干扰半静态分簇( AlSSC)路由算法,给无线传感器网络提供能量多、距离短、链路质量好的路径来传输数据.该算法利用节点定位获取节点地理位置,综合考虑传感器节点剩余能量和干扰信噪比,通过节点距离度量、节点聚簇、簇间融合、簇头选举和簇头轮换五个步骤进行无线传感器网络节点的分簇.仿真结果表明:这种路由算法可以提高无线传感器网络通信链路质量,均衡网络能量消耗.     

Loop-free hybrid single-path/flooding routing algorithms withguaranteed delivery for wireless networks

In a localized routing algorithm, each node makes forwarding decisions solely based on the position of itself, its neighbors, and its destination. In distance, progress, and direction-based approaches'(reported in the literature), when node A wants to send or forward message m to destination node D, it forwards m to its neighbor C which is closest to D (has best progress toward D, whose direction is closest to the direction of D, respectively) among all neighbors of A. The same procedure is repeated until D, if possible, is eventually reached. The algorithms are referred to as GEDIR, MFR, and DIR when a common failure criterion is introduced: The algorithm stops if the best choice for the current node is the node from which the message came. We propose 2-hop GEDIR, DIR, and MFR methods in which node A selects the best candidate node C among its 1-hop and 2-hop neighbors according to the corresponding criterion and forwards m to its best 1-hop neighbor among joint neighbors of A and C. We then propose flooding GEDIR and MFR and hybrid single-path/flooding GEDIR and MFR methods which are the first localized algorithms (other than full flooding) to guarantee the message delivery (in a collision-free environment). We show that the directional routing methods are not loop-free, while the GEDIR and MFR-based methods are inherently loop free. The simulation experiments, with static random graphs, show that GEDIR and MFR have similar success rates, which is low for low degree graphs and high for high degree ones. When successful, their hop counts are near the performance of the shortest path algorithm. Hybrid single-path/flooding GEDIR and MFR methods have low communication overheads. The results are also confirmed by experiments with moving nodes and MAC layer     

移动社会网络中基于社区的消息机会传输策略

移动社会网络是一种由大量具有社会特征的节点组成的机会网络.已有的基于社区的路由算法大多选用社会性最优的节点参与转发,而没有考虑到社区分布对节点移动的影响,将这些算法直接用于移动社会网络中会导致网络资源消耗高、传输成功率低等问题.针对这些问题,提出一种基于社区的消息机会传输算法,在社区间根据节点到目标社区的传输概率选择社区间的最优传输路径,在社区内选择与目标节点相遇概率较高的节点完成社区内传输.仿真实验结果表明,在移动社会网络中,该算法与 Prophet,Spray and Wait 等经典算法相比,提高了消息传输成功率,降低了网络开销.     

A broadcast algorithm for all-port wormhole-routed torus networks

A new approach to broadcast in wormhole-routed two- and three-dimensional torus networks is proposed. The underlying network is assumed to support only deterministic, dimension-ordered unicast routing. The approach extends the graph theoretical concept of dominating nodes by accounting for the relative distance-insensitivity of the wormhole routing switching strategy. The proposed algorithm also takes advantage of an all-port communication architecture, which allows each node to simultaneously transmit messages on different outgoing channels. The resulting broadcast operation is based on a tree structure that uses multiple levels of extended dominating nodes(EDNs). Performance results are presented that confirm the advantage of this method over other approaches     

Broadcasting on Incomplete WK-Recursive Networks

The WK-recursive networks, which were originally proposed by Vecchia and Sanges, have suffered from a rigorous restriction on the number of nodes. Like other incomplete networks, the incomplete WK-recursive networks have been proposed to relieve this restriction. In this paper, broadcasting on the incomplete WK-recursive networks is discussed. The proposed broadcasting algorithm is optimal with respect to message complexity. Besides, extensive experiments are made to evaluate its performance. Experimental results show that (1) the heights of the broadcasting trees do not exceed the diameters, (2) a high percentage of the nodes can receive the message from the source node via the shortest paths, (3) for those nonshortest transmission paths, the deviations are small, and (4) a high percentage of the broadcasting trees are of minimum height.     

Routing Function and Deadlock Avoidance in a Star Graph Interconnection Network

In this paper the properties of paths in a star graph are investigated through the analysis of the corresponding star transposition tree. The general algebraic expression for all shortest paths between any two nodes (routing function) is found, and it is shown that every shortest path consists of a number of subpaths which can be combined in an arbitrary order or even mutually nested. Further, due to the known routing function the deadlock problem is solved using the method of virtual channels. A minimal deterministic routing algorithm is developed which recognizes the structure of the path by extracting subpaths and allows optimal adaptive management of virtual channels. Finally, based on the sufficient number of virtual channels, the minimal fully adaptive routing algorithm is suggested which offers an opportunity to reroute the message a number of times, while maintaining the shortest path between two nodes.     

YOMNA – An efficient deadlock-free multicast wormhole algorithm in 2-D mesh multicomputers

A mesh network is a popular architecture which has been implemented in many multicomputer systems. It is preferred because it offers useful edge connectivity and is partitioned into units that are still meshes. It is also scalable and has a number of features that make it particularly amenable to high-performance computing. The 2-D mesh topology has become increasingly important to multicomputer design because of its many desirable properties including scalability, low bandwidth and fixed degree of nodes.The essential pattern in new multicomputer generations is the multicast wormhole pattern, which corresponds to one-to-many communication in which one source sends the same message to multiple destination nodes. In wormhole routing, a message is decomposed into words or flits, and flits of one message may be spread out among several nodes. Deadlock in the interconnection network occurs when no message can advance towards its destination. Some deadlock-free routing algorithms for wormhole routing were proposed, but the network latency and the network traffic were not taken into consideration. An optimal message routing should achieve both minimum traffic and minimum latency for the communication patterns involved. Unfortunately, finding optimal message routing has been shown to be NP-hard for most common multicomputer topologies.In this paper, an efficient algorithm (YOMNA) is introduced to find a deadlock-free multicast wormhole routing in 2-D mesh parallel machines. YOMNA algorithm is a tree-based technique, in which the router simultaneously sends incoming flits on more than one outgoing channel. YOMNA algorithm is compared with the dual-path multicast routing, which is a path-based technique. YOMNA algorithm has proved to be deadlock free. The network latency and the network traffic are calculated for YOMNA algorithm and for the dual-path multicast routing. The results demonstrate that YOMNA algorithm outperformed the dual-path routing.     

An improved topology discovery algorithm for networks with wormhole routing and directed links

We propose a new parallel topology discovery algorithm for irregular, mesh-connected networks with unidirectional links and wormhole routing. An algorithm of this type was developed for the ATOMIC high speed local area network to avoid the need for manually updating routing tables. Similar needs may arise in wireless networks where channels may be unidirectional because of limited transmission power, multipath, and similar effects. Like the ATOMIC topology discovery algorithm, our algorithm accumulates a map of the network at a distinguished node called the Address Consultant. However, our algorithm is much faster. In addition, our algorithm is more general, because it can correctly resolve topologies that contain multiple links between the same nodes. We implemented both algorithms in a concurrent simulation environment, and tested them on a variety of topologies.     

Mesh网络容错广播路由算法的概率分析

One-to-all or broadcast communication is one of the most important communication patterns and occurs in many important applications in parallel computing. This paper proposes a fault tolerant, local-irdormation-based, and distributed broadcast routing algorithm based on the concept of k-submesh-cormectivity in all-port mesh networks.The paper analyzes the fault tolerance of the algorithm in terms of node failure probability. Suppose that every nodehas independent failure probability, and deduce the success probability of the broadcast routing, which successfully routes a message from a source node to all non-faulty nodes in the networks. The paper strictly proves that the broadcast routing algorithm with the success probability of 99％ to route among all non-faulty nodes on mesh networks with forty thousand nodes, in case that the node failure probability is controlled within 0.12％ Simulation results show that the algorithm is practically efficient and effective, and the time steps of the algorithm are very closeto the optimum.     

基于消息摆渡的机会网络全覆盖低时延路由算法

针对现有基于消息摆渡的机会网络路由算法中存在的网络覆盖不全、Ferry节点主动运动路径不够优化以及Beacon消息包含冗余字段等问题,提出一种新的路由算法—优化的摆渡路由算法(Optimized Ferry Routing, OFR),该算法采用自适应调整Ferry节点通信半径消除网络覆盖盲区、优化选择Ferry节点主动运动路径,使尽可能多的节点相遇以及删除Beacon消息中冗余的位置信息3种新机制,在不影响原有数据传输功能的前提下改善网络覆盖,提高数据分组传送成功率、降低数据分组时延和控制开销。理论分析和仿真结果表明：与FIMF、MO-FIMF和FTFPF算法相比,OFR算法的数据分组传送成功率至少提高了3.83%,而平均端到端时延和控制开销则分别降低了1.23%和 6.34%以上。     

A Routing Algorithm with Candidate Shortest Path

An improved algorithm based on the next node routing principle is proposed in this paper.In this algorithm there is a column added to the classical routing table, in which the candidateshortest distance to the destination node is the entry. When a link fails, the new shortest path inthe nodes connected directly with the failure link can be found immediately (it is just thecandidate shortest path before failure). For all other nodes in which routing tables should bechanged, the required number of control messages and time for convergence are also less thanTajibnapis' algorithm and Predecessor algorithm. The message looping problem does not existin duplex loop networks and is radically improved in mesh networks. These statements areproved by the analysis and simulation in this paper. From the simulation results of a 30-nodemesh network, when one link goes down, the total number of control messages generatedduring convergence with this algorithm on the average is about 30% of Tajibnapis' algorithm.The iterations required is 50% of Tajibnapis' algorithm. The memory space required andcomputation complexity in nodes are almost the same as the two algorithms mentioned aboveand the algorithm implementation is as easy as well.     

An extended dominating node approach to broadcast and globalcombine in multiport wormhole-routed mesh networks

A new approach to the design of collective communication operations in wormhole-routed mesh networks is described. The approach extends the concept of dominating sets in graph theory by accounting for the relative distance-insensitivity of the wormhole switching strategy and by taking advantage of a multiport communication architecture, which allows each node to simultaneously transmit messages on different outgoing channels. Collective communication operations are defined in terms of sets of extended dominating nodes (EDNs). The nodes in a set of EDNs can deliver (receive) messages to (from) a different, larger set of nodes in a single message-passing step under dimension-ordered wormhole routing and without channel contention among messages. The EDN model can be applied to different collective operations in 2D and 3D mesh networks. The authors focus on EDN-based broadcast and global combine operations. Performance evaluation results are presented that confirm the advantage of this approach over other methods     

基于最短路径树的优化生存时间路由算法

为提高无线传感网的生存时间,提出基于最短路径树的优化生存时间路由算法(LORA_SPT).该算法引入节点分类概念,构造基于链路能耗因子、自身节点剩余能量因子、邻居节点剩余能量因子和类型权重因子等多个因子的权值函数.针对不同类型的节点采用不同的权重因子,最后利用dijkstra算法完成最短路径树,所有节点沿着最短路径树将...     

多跳无线网络跨层协作式路由协议实现和性能分析

为了提高多跳无线网络的带宽利用率, 引入了辅助节点来帮助其他链路进行数据传输并重新定义了协作式路由的概念。在此基础上, 提出了协作式路由算法, 并且在实际平台上进行了实验。结果表明, 协作式路由能够显著提高网络传输带宽。