MANET 中基于链路稳定性路由的跨层传输控制协议

在MANET中,通信节点的移动会造成端到端通信路由的时常中断.传统TCP协议只有拥塞控制机制,对由于节点移动造成的数据包传输丢失和超时也作为拥塞处理,使得端到端传输性能低下.为解决这一问题,采用跨层设计思想,将传输控制与链路稳定性路由结合,提出了一种基于链路生存时间概率的传输控制协议(transmissioncontrol protocol based on probability of link residual lifetime,简称TCP-PLRT).该协议通过在路由稳定时跨层收集路由层链路生存时间概率信息来实现对端到端连接稳定性的认知,并针对路由不稳定、路由中断、路由恢复,分别制定了路由切换、数据存储转发、ACK再确认三大机制.这使得TCP-PLRT协议具有对由移动造成的路由中断进行提前预判和有效处理的能力.仿真结果表明,TCP-PLRT协议能够极大地减小由节点移动带来的端到端传输性能的下降,减少分组重传,提高端到端的吞吐量.     

基于跨层链路质量状态感知的无人机地理位置路由协议

地理位置路由协议由于开销较低和可扩展性较好而在FANET网络中得到了广泛应用，但其贪婪转发过程中依据最靠近目的地的邻居节点作为中继的策略还存在一定的局限性。文中通过感知链路质量，提出了一种适用于拓扑变化频繁、网络环境拥挤的跨层链路质量状态感知的无人机地理位置路由协议(CLAQ-GPSR)。通过设立通信安全区，建立链路负载和流间干扰度量模型，采用交付比ETX衡量链路质量，结合物理层、MAC层、网络层数据综合衡量最可靠的中继节点，以提升通信质量。同时采用左右手组合转发规则，加快路径恢复中的转发速度，避免传统周边转发出现的路由循环等问题。通过网络仿真平台比对分析可知，相比传统的GPSR,W-GeoR和DGF-ETX协议，所提协议在数据包分组投递成功率、端到端时延和跳数等指标上更具优势。     

基于蚁群优化的AdHoc网络生存时间和其他网络性能平衡路由协议

本文提出了基于蚁群优化(ACO)算法的Ad Hoc网络生存时间和其他网络性能平衡路由协议(ABEAR)。协议按需发送人工蚂蚁进行路由发现,综合节点残留的信息素浓度、下一跳节点剩余能量、节点周围链路质量和拥塞情况选择下一跳节点来转发数据包,尽量避开信道使用频率较高的路径,减少了因信道冲突、数据包丢失和数据包重传所造成的能量损失,还缩短了网络传输时延,提高了网络吞吐量。协议还采用跨层机制根据MAC层通信活动情况,在保证网络连通性的前提下使部分空闲节点转入睡眠状态来节省能量消耗。仿真表明,与AODV协议相比,ABEAR协议在网络生存时间、数据包交付率和端到端平均时延方面均有较大改善。     

无线mesh传感器网络跨层路由算法

针对无线mesh传感器网络的需求,提出一种综合量度的跨层路由协议H工.S。算法H工S利用底层的链路质 量信息、MAC层时隙分配信息,结合跳数对备选路径做出综合判断,避开质量较差的链路和负载较重的节点。路由发 现过程中在中间节点设置链路质量和节点负载阂值,并根据相关信息进行延时转发操作,以减少不必要的路由开销。 在路由维护阶段使用主动和被动相结合的方式全面检测路由路径。NS2的仿真结果表明,HLS协议在吞吐量、端到 端时延以及网络生存时间上有更好的表现。     

一种基于链路质量的移动Ad-hoc网络地理路由算法

如何实现简单的路由机制,使节点能够快速、高效地完成分组传递,是移动aa-ho}网络研究的一个基本问题。针对无线链路在高误码率和杭干扰技术方面的不足,提出了将链路质量作为路由选择的度量,设计并实现了基于链路质量的地理路由算法LQPR,解决了在非理想无线链路上采用传统贪婪算法引起数据分组传送率下降的问题。该算法综合了链路质量选择模式和边界选择模式,并利用目标定位技术获取的地理位置信息指导分组的转发,以减少控制开销,优化路径选择,实现数据分组快速有效的传输。在NS-2中完整实现了LQPR协议的仿真,并通过对网络节点发送数据包的端到端时延、吞吐量以及包传送率进行比较、评估和检侧,验证了LQPR路由协议的有效性。     

一种基于链路质量的移动Ad-hoc网络地理路由算法

如何实现简单的路由机制,使节点能够快速、高效地完成分组传递,是移动Ad-hoc网络研究的一个基本问题.针对无线链路在高误码率和抗干扰技术方面的不足,提出了将链路质量作为路由选择的度量,设计并实现了基于链路质量的地理路由算法LQPR,解决了在非理想无线链路上采用传统贪婪算法引起数据分组传送率下降的问题.该算法综合了链路质量选择模式和边界选择模式,并利用目标定位技术获取的地理位置信息指导分组的转发,以减少控制开销,优化路径选择,实现数据分组快速有效的传输.在NS-2中完整实现了LQPR协议的仿真,并通过对网络节点发送数据包的端到端时延、吞吐量以及包传送率进行比较、评估和检测,验证了LQPR路由协议的有效性.     

城市环境下跨层VANET路由协议研究

车载自组织网络(VANET)单一分层结构路由协议考虑因素较少,导致分组投递率低、端到端时延较高。为此,考虑车辆位置、速度、路口密度、无线链路质量、MAC层误帧率等影响因素,提出一种应用于城市环境的基于位置信息的VANET跨层路由协议(MCLPR)。设计路口车辆节点选择算法提取无线链路质量和MAC层误帧率的跨层信息,采用层次分析法计算各影响因素的权重值,确定最佳转发路径。仿真结果表明,与AODV,DSDV等路由协议相比,MCLPR路由协议具有较高的分组投递率及较低的端到端时延,保证了数据传输的可靠性与高效性,适用于网络密度与负载较大、车辆移动速度较快的城市环境。     

一种基于Ad hoc网络AODV协议的不相交节点多路径路由算法

针对Ad hoc 网络低功耗无线通信的链路不确定性、链路质量不稳定性以及节点失效等问题,基于AODV路由协议提出了不相关节点路由算法。该算法使用简单的数字标志来搜寻不相关节点路径,并通过设置节点的阈值判断链路质量和失效节点来确定可靠的路由链路。仿真实验表明,该算法有很好的报文投递率,并能有效地减少网络链路中断的数量,降低端到端的延迟。     

基于路由数目的通信链路重要性分析

为了分析通信网络中通信链路对端到端通信的重要程度,提出一种基于路由数目的链路重要性计算方法。该方法采用一种快速算法,寻找出端到端的所有通信路由,再通过比较不同通信链路的损坏使端到端之间传输路由减少的数目,判断不同通信链路对端到端通信的重要性,如果某通信链路损坏导致路由减少越多,则该链路越重要。计算实例表明,该方法计算简单,易于编程实现,具有一定的实用性和有效性。     

基于综合判据的无线Mesh网路由协议

为用户提供高质量、高性能的通信链路是无线Mesh网路由协议所面临的重要挑战,而当前从Ad Hoc网络沿袭下来的路由协议并不能够满足无线Mesh网的性能要求.文中以OLSR协议为原型,结合跨层优化理论,为基础设施架构的无线Mesh网提出了一种新颖的、基于综合判据的路由协议.该协议通过跨层操作机制综合考虑无线链接的长度及通信效率对链接性能的影响,从而达到优化路由选择的效果.仿真结果表明,所提出的路由协议能够有效地提高网络中分组的递交率,降低端到端的延时,并且能够在一定程度上达到负载均衡的路由效果.     

Beacon-Less Geographic Routing in Real Wireless Sensor Networks

Geographic Routing(GR)algorithms require nodes to periodically transmit HELLO messages to allow neigh- bors to know their positions(beaconing mechanism).Beacon-less routing algorithms have recently been proposed to reduce the control overheads due to these messages.However,existing beacon-less algorithms have not considered realistic physical layers.Therefore,those algorithms cannot work properly in realistic scenarios.In this paper we present a new beacon- less routing protocol called BOSS.Its design is based on the conclusions of our open-field experiments using Tmote-sky sensors.BOSS is adapted to error-prone networks and incorporates a new mechanism to reduce collisions and duplicate messages produced during the selection of the next forwarder node.We compare BOSS with Beacon-Less Routing(BLR) and Contention-Based Forwarding(CBF)algorithms through extensive simulations.The results show that our scheme is able to achieve almost perfect packet delivery ratio(like BLR)while having a low bandwidth consumption(even lower than CBF).Additionally,we carried out an empirical evaluation in a real testbed that shows the correctness of our simulation results.     

基于定向广播的AODV控制报文抑制研究

AODV路由协议是通过全向广播请求报文和定时广播Hello报文来建立Ad Hoc网络的路由,但在路由发现阶段需要广播发送大量的请求控制报文,导致了协议性能的下降。针对此问题,提出了一种新的基于定向广播的路由协议,该协议通过定向广播发送请求报文,并根据节点的移动性动态调整Hello报文的发送时间间隔来减少报文的发送。理论分析和仿真结果表明,该方法能有效地减少控制报文的数量,减少路由负载,也显著提高了端到端时延、平均投递率等性能参数。     

Dynamic route maintenance for geographic forwarding in mobile ad hoc networks

Traditional route maintenance requires mobile nodes periodically exchange beacon messages with their neighbors in geographic forwarding algorithms. The interval at which these nodes broadcast their beacon messages is typically fixed. However, determining an appropriate value for this interval is challenging. A longer interval reduces the number of beacons needed, but may result in significant location errors. Conversely, a shorter interval guarantees more accurate location information, but induces heavier control overheads. Additionally, since a fixed value is assigned to the lifetime of each routing entry, the forwarding algorithm cannot adapt well to different mobility environments. Therefore, this paper presents a dynamic route maintenance algorithm (DRM) for beacon-based geographic routing. In the approach, the mobile nodes dynamically adjust their beacon intervals based on their speed of movement. Moreover, the routing information can be well managed using the mobility prediction. The simulation results show that DRM not only significantly decreased the routing overheads in a low mobility scenario but also guaranteed the high quality packet delivery in high mobility environments.     

无线 Ad hoc 网络和传感网络中基于位置的、可靠的无信标传输路由方法

Existing position-based routing algorithms, where packets are forwarded in the geographic direction of the destination, normally require that the forwarding node should know the positions of all neighbors in its transmission range. This information on direct neighbors is gained by observing beacon messages that each node sends out periodically. Several beaconless greedy routing schemes have been proposed recently. However, none of the existing beaconless schemes guarantee the delivery of packets. Moreover, they incur communication overhead by sending excessive control messages or by broadcasting data packets. In this paper, we describe how existing localized position based routing schemes that guarantee delivery can be made beaconless, while preserving the same routes. In our guaranteed delivery beaconless routing scheme, the next hop is selected through the use of control RTS/CTS messages and biased timeouts. In greedy mode, the neighbor closest to destination responds first. In recovery mode, nodes closer to the source will select shorter timeouts, so that other neighbors, overhearing CTS packets, can eliminate their own CTS packets if they realize that their link to the source is not part of Gabriel graph. Nodes also cancel their packets after receiving data message sent by source to the selected neighbor. We analyze the behavior of our scheme on our simulation environment assuming ideal MAC, following GOAFR+ and GFG routing schemes. Our results demonstrate low communication overhead in addition to guaranteed delivery.     

Wait-free deflection routing of long messages

In order to obtain the lowest possible latency, routing algorithms should try to avoid a message waiting for resources (network links) blocked by other messages or multiplexing of more messages over one physical channel. This requirement becomes especially important in the case of long messages. The only type of protocols able to guarantee waiting free routing under heavy load are algorithms based on deflection (also called nonminimal adaptive or hot potato) routing. This paper deals with problems connected with the use of deflection algorithms. In contrast to the case of nonadaptive or partially (e.g., minimal) adaptive routing, it is very infrequent that an unrestricted deflection routing becomes deadlocked and, similarly, livelock is not a serious problem. On the other hand, there is another phenomenon, called a deflection jam, that limits throughput of deflection algorithms used to route long messages. It has been observed for many deflection heuristics, interconnection network topologies, and both virtual cut-through and wormhole routing. A deflection jam is a sudden and persistent saturation of a network which sometimes occur, after a very long period of undisturbed communication. This paper describes events that trigger this saturation which suggest ways to design improved and stable deflection routing algorithms     

A routing protocol suitable for backhaul access in wireless mesh networks

This work proposes the Wireless-mesh-network Proactive Routing (WPR) protocol for wireless mesh networks, which are typically employed to provide backhaul access. WPR computes routes based on link states and, unlike current routing protocols, it uses two algorithms to improve communications in wireless mesh networks taking advantage of traffic concentration on links close to the network gateways. WPR introduces a controlled-flooding algorithm to reduce routing control overhead by considering the network topology similar to a tree. The main goal is to improve overall efficiency by saving network resources and avoiding network bottlenecks. In addition, WPR avoids redundant messages by selecting a subset of one-hop neighbors, the AMPR (Adapted MultiPoint Relay), needed to reach all two-hop ones. We first analyze the proposed algorithms compared with the algorithms used by OLSR for the same tasks in terms of running time, optimality, and number of routing messages. Results show that the algorithms proposed by WPR are more efficient than the algorithms used by OLSR in running time and number of routing messages. In addition, we also perform simulations to evaluate the performance of WPR. Results reveal that the aggregated throughput of WPR outperforms OLSR by up to 27% using a combination of web and backbone internal traffic despite our design assumption of traffic convergence toward gateways.     

Multicast communication in wormhole-routed 2D torus networks with hamiltonian cycle model

In this paper, we propose an efficient multipath multicast routing algorithm in wormhole-routed 2D torus networks. We first introduce a hamiltonian cycle model for exploiting the feature of torus networks. Based on this model, we find a hamiltonian cycle in torus networks. Then, an efficient multipath multicast routing algorithm with hamiltonian cycle model (mulitpath-HCM) is presented. The proposed multipath multicast routing algorithm utilizes communication channels more uniformly in order to reduce the path length of the routing messages, making the multicasting more efficient. Simulation results show that the multicast latency of the proposed multipath-HCM routing algorithm is superior to that of fixed and dual-path routing algorithms.     

An optimal fault-tolerant routing algorithm for weighted bidirectional double-loop networks

Double-loop networks are widely used in computer networks. In this paper, we present an optimal message routing algorithm and an optimal fault-tolerant message routing algorithm for weighted bidirectional double-loop networks. The algorithms presented are novel, and they do not use routing tables. After a precalculation of O(log N) steps to determine network parameters, the algorithms can route messages using constant time at each node along the route. The algorithm presented can route messages in the presence of up to three faulty nodes or links. The fault-tolerant routing algorithm guarantees an optimal route in the presence of one node failure.     

基于多队列自适应的DTN传染路由算法

传染路由是DTN中一类较简单的基本路由算法.针对DTN网络环境易变的特点及传染路由的不足提出多队列自适应传染路由,采用多队列方式管理存储空间,利用效用函数对队列内信息进行排序,针对不同队列及网络情况采用相异的转发机制,从而降低网络负载率、提高传输率并降低传输时延,同时可提供简单的QoS.仿真证明本算法优于路由算法Spray andw ait和MaxProp.     

基于社会性的DTN网络路由算法研究

针对DTN网络中的消息传输问题,结合概率路由算法PROPHET和社会性路由算法SimBet的基本思想,提出一种DTN网络路由算法——ProSimbet。在选择转发节点时,综合考虑基于历史相遇记录的概率估计和节点的社会性这2个指标,从而降低消息转发次数。实验结果表明,在密集数据集INFOCOM06上,ProSimBet、SimBet、PROPHET和ER这4种路由算法的消息成功转发数目比较接近。在稀疏数据集MIT上,ProSimBet在消息转发次数上比SimBet降低26.1%,在消息成功转发数目上比PROPHET提高7.83%。