共查询到19条相似文献,搜索用时 62 毫秒
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基于随机竞争和冲突解决的思想,本文为多跳移动Ad Hoc网络提出了一种分布式服务质量(QoS)保证的多址接入(QMA)协议.该协议中,节点在发送业务分组前利用预报突发进行竞争接入,节点根据业务分组时延情况和最早失效优先原则确定预报突发的长度,所发预报突发能持续到最后的节点优先获得接入.同时,具有实时业务的节点可以按照其优先级在更早的竞争微时隙中开始发送预报突发,而有非实时业务的节点只能在前面竞争微时隙空闲的情况下,才能在后面的微时隙开始发送预报突发,因此发送实时业务的节点可以比发送非实时业务的节点更优先接入信道,从而在移动Ad Hoc网络中实现了对多媒体业务的QoS保证.最后利用OPNET仿真评估了QMA协议的多址性能,并与IEEE 802.11e协议的性能做了比较,结果表明QMA协议可以提供较高的吞吐量和较低的实时业务时延. 相似文献
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无线移动Ad Hoc网络作为可移动分布式多跳无线网络,没有预先确定的网络拓扑或网络基础设施以及集中控制。为了在这样的网络中促进通信,路由协议主要用于在节点之间发现路径。Ad Hoc网络路由协议的主要目的是网络拓扑的动态变化任意两个节点之间建立一个使得通信总费用和带宽消费最少的正确和有效的通信路径。使用OPNET仿真软件对AODV、DSR协议这两种典型无线移动Ad Hoc网络按需路由协议的参数和性能进行了详细比较和分析。 相似文献
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移动Ad hoc网络中基于链路稳定性预测的按需路由协议 总被引:4,自引:0,他引:4
移动Ad hoc网络拓扑的高度动态变化是造成传统按需路由协议的路由频繁通断的主要原因,因此在传统按需路由协议的基础上进行链路稳定性预测扩展,增强路由稳定性具有十分重要的意义。该文利用分组的接收功率把节点间的相对运动划分为靠近和远离两种类型,然后在不同相对运动类型下根据节点间距离得到了的链路平均维持时间。在路由过程中,中间节点利用得到的链路平均维持时间设置请求报文的转发延迟,通过一定转发规则选择稳定性较强的链路构成路径。仿真结果表明进行链路稳定性预测扩展后的按需路由协议能够有效增强路由的稳定性,并提高网络性能。 相似文献
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本文提出了一种应用于移动Ad Hoc网络中的功率控制MAC(medium access contr01)协议,通过两个通信节点之间的控制包中的信息交换来决定数据包的发送功率以及其它邻节点下一次发送RTS控制包的功率。通过仿真与IEEE 802.11 MAC协议进行比较,由仿真结果可以看出,该协议能大大减少移动节点消耗的功率,提高节点的能量利用效率,并保持系统的吞吐量性能。 相似文献
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Ad Hoc网络中MAC协议的研究是一个全新的领域,正逐步受到人们的关注。在移动Ad Hoc网络中,有时会有多个无线设备同时接入信道,从而导致分组之间发生矛盾,致使接收机无法辨认接收到的数据资料,出现信道资源浪费的现象。 相似文献
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Ariadne: A Secure On-Demand Routing Protocol for Ad Hoc Networks 总被引:9,自引:0,他引:9
An ad hoc network is a group of wireless mobile computers (or nodes), in which individual nodes cooperate by forwarding packets for each other to allow nodes to communicate beyond direct wireless transmission range. Prior research in ad hoc networking has generally studied the routing problem in a non-adversarial setting, assuming a trusted environment. In this paper, we present attacks against routing in ad hoc networks, and we present the design and performance evaluation of a new secure on-demand ad hoc network routing protocol, called Ariadne. Ariadne prevents attackers or compromised nodes from tampering with uncompromised routes consisting of uncompromised nodes, and also prevents many types of Denial-of-Service attacks. In addition, Ariadne is efficient, using only highly efficient symmetric cryptographic primitives. 相似文献
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Performance of Multipath Routing for On-Demand Protocols in Mobile Ad Hoc Networks 总被引:25,自引:0,他引:25
Mobile ad hoc networks are characterized by multi-hop wireless links, absence of any cellular infrastructure, and frequent host mobility. Design of efficient routing protocols in such networks is a challenging issue. A class of routing protocols called on-demand protocols has recently found attention because of their low routing overhead. The on-demand protocols depend on query floods to discover routes whenever a new route is needed. Such floods take up a substantial portion of network bandwidth. We focus on a particular on-demand protocol, called Dynamic Source Routing, and show how intelligent use of multipath techniques can reduce the frequency of query floods. We develop an analytic modeling framework to determine the relative frequency of query floods for various techniques. Our modeling effort shows that while multipath routing is significantly better than single path routing, the performance advantage is small beyond a few paths and for long path lengths. It also shows that providing all intermediate nodes in the primary (shortest) route with alternative paths has a significantly better performance than providing only the source with alternate paths. We perform some simulation experiments which validate these findings. 相似文献
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A mobile ad hoc network (MANET) is characterized by multi-hop wireless links and frequent node mobility. Communication between non-neighboring nodes requires a multi-hop routing protocol to establish a route. But, the route often breaks due to mobility. The source must rediscover a new route for delivering the data packets. This wastes the resources that are limited in MANET. In this paper, a new on-demand routing protocol is proposed, named on-demand routing protocol with backtracking (ORB), for multi-hop mobile ad hoc networks. We use the multiple routes and cache data technique to reduce the rediscovery times and overhead. After executing the route discovery phase, we find out a set of nodes, named checkpoint, which has the multiple routes to the destination. When a checkpoint node receives a data packet, it caches this data packet in its buffer within a specific time period. When a node detects a broken route during the data packets delivery or receives an error packet, it will either recover the broken route or reply the error packet to the source. If a node can not forward the data packet to the next node, it replies an error packet to the source. This packet is backtracking to search a checkpoint to redeliver the data packet to the destination along other alternate routes. The main advantage of ORB is to reduce the flooding search times, maybe just delay and cost while a route has broken. The experimental results show that the proposed scheme can increase the performance of delivery but reduce the overhead efficiently comparing with that of AODV based routing protocols.
Hua-Wen Tsai received the B.S. degree in Information Management from Chang Jung Christian University, Taiwan, in June 1998 and the M.B.A. degree in Business and Operations Management from Chang Jung Christian University, Taiwan, in June 2001. Since September 2001, he has been working towards the Ph.D. degree and currently is a doctoral candidate in the Department of Computer Science and Information Engineering, National Cheng Kung University, Taiwan. His research interests include wireless communication, ad hoc networks, and sensor networks.
Tzung-Shi Chen received the B.S. degree in Computer Science and Information Engineering from Tamkang University, Taiwan, in June 1989 and the Ph.D. degree in Computer Science and Information Engineering from National Central University, Taiwan, in June 1994. He joined the faculty of the Department of Information Management, Chung Jung University, Tainan, Taiwan, as an Associate Professor in June 1996. Since November 2002, he has become a Full Professor at the Department of Information Management, Chung Jung University, Tainan, Taiwan. He was a visiting scholar at the Department of Computer Science, University of Illinois at Urbana-Champaign, USA, from June to September 2001. He was the chairman of the Department of Information Management at Chung Jung University from August 2000 to July 2003. Since August 2004, he has become a Full Professor at the Department of Information and Learning Technology, National University of Tainan, Tainan, Taiwan. Currently, he is the chairman of the Department of Information and Learning Technology, National University of Tainan. He co-received the best paper award of 2001 IEEE ICOIN-15. His current research interests include mobile computing and wireless networks, mobile learning, data mining, and pervasive computing. Dr. Chen is a member of the IEEE Computer Society.
Chih-Ping Chu received the B.S. degree in agricultural chemistry from National Chung Hsing University, Taiwan, the M.S. degree in computer science from the University of California, Riverside, and the Ph.D. degree in computer science from Louisiana State University. He is currently a Professor in the Department of Computer Science and Information Engineering of National Cheng Kung University, Taiwan. His current research interests include parallel computing, parallel processing, component-based software development, and internet computing. 相似文献
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ABRP: Anchor-based Routing Protocol for Mobile Ad Hoc Networks 总被引:2,自引:0,他引:2
Ad hoc networks, which do not rely on any infrastructure such as access points or base stations, can be deployed rapidly and
inexpensively even in situations with geographical or time constraints. Ad hoc networks are attractive in both military and
disaster situations and also in commercial uses like sensor networks or conferencing. In ad hoc networks, each node acts both
as a router and as a host. The topology of an ad hoc network may change dynamically, which makes it difficult to design an
efficient routing protocol. As more and more wireless devices connect to the network, it is important to design a scalable
routing protocol for ad hoc networks. In this paper, we present Anchor-based Routing Protocol (ABRP), a scalable routing protocol
for ad hoc networks. It is a hybrid routing protocol, which combines the table-based routing strategy with the geographic
routing strategy. However, GPS (Global Positioning System) (Kaplan, Understanding GPS principles and Applications, Boston:
Artech House publishers, 1996) support is not needed. ABRP consists of a location-based clustering protocol, an intra-cell
routing protocol and an inter-cell routing protocol. The location-based clustering protocol divides the network region into
different cells. The intra-cell routing protocol routes packets within one cell. The inter-cell routing protocol is used to
route packets between nodes in different cells. The combination of intra-cell and inter-cell routing protocol makes ABRP highly
scalable, since each node needs to only maintain routes within a cell. The inter-cell routing protocol establishes multiple
routes between different cells, which makes ABRP reliable and efficient. We evaluate the performance of ABRP using ns2 simulator.
We simulated different size of networks from 200 nodes to 1600 nodes. Simulation results show that ABRP is efficient and scales
well to large networks. ABRP combines the advantages of multi-path routing strategy and geographic routing strategy—efficiency
and scalability, and avoids the burden—GPS support. 相似文献
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In order to resolve the hidden and exposed terminal problems and improve the probability of concurrent packet transmissions for multihop Mobile Ad Hoc Networks (MANETs), a novel slotted Asymmetric Dual-Channel Medium Access Control (ADC-MAC) protocol is proposed. It exploits simultaneous reservation with less collisions and collision-free data packet transmissions, and achieves optimal transmission balance on the Control Channel (CCH) and Data Channel (DCH) by adjusting the relationship between Reservation Slot (RS) on the CCH and the data packet Transmission Slot (TS) on the DCH. Transmission interferences can be avoided by only observing CCH for the transmission time of a data packet. The proposed RS and contention micro-slot backoff mechanisms also greatly improve channel access efficiency. Simulation results show that compared to IEEE 802.11 DCF and p-Mc protocols, the proposed protocol can achieve a throughput gain of 88% in single-hop networks and 151% in multihop networks at the same total data rate. 相似文献