能量感知的GPSR动态路由负载均衡

贪婪周边无状态路由协议（GPSR）在Ad Hoc和传感器网络中有广泛的应用,GPSR的路由是以距离目的坐标最近的原则进行选路的,容易形成热点路由,从而缩短网络的生存时间。基于对邻居传感器节点的能量感知,提出了有动态负载均衡能力的GPSR路由算法。该算法能够根据网络节点的能量情况动态调整路由。仿真结果表明提出的具有动态路由负载均衡能力的GPSR算法能有效延长网络的生存时间。     

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.     

基于方向预测的移动自组网概率转发算法

移动自组网中传统的路由算法大多采用拉网式的盲搜索,导致路由开销较大,针对这一问题,提出一种基于方向预测的概率转发算法。该算法通过监听网络中传输的各种数据包,从中提取节点ID和时间信息,这些信息反映了到目的节点的距离;在此基础上,计算节点的转发概率,并根据网络的变化自适应地调整,使得路由过程始终沿着目的节点所在方向进行,限定了搜索区域。仿真结果表明,该算法的路由开销比洪泛降低了70%,比经典概率转发算法降低了20%,提高了网络性能。     

Location verification and trust management for resilient geographic routing

In this paper, we consider the security of geographic routing (GR) protocols. In GR, neighbors exchange their location information. Based on this information, a node forwards packets to the neighbor that is closest to the destination. Although GR is widely used in ad hoc and wireless sensor networks, its security has rarely been studied; there are a number of attacks that are possible on GR. In one attack, misbehaving nodes can falsify their location information. Also, malicious nodes can drop packets that they need to forward towards the destination. The first contribution of the paper is to propose a location verification algorithm to address the attacks falsifying the location information. The second contribution of the paper is to propose approaches for trust-based multi-path routing, aiming to defeat attacks on GR. We discuss the proposed approaches in detail, outlining possible attacks and defenses against them. In addition, we show, via simulation, how trust-based route selection is able to circumvent attackers and route around them. This paper summarizes and extends results reported by the authors in a previous article [K.-D.K. Nael, B. Abu-Ghazaleh, K. Liu, Towards resilient routing in WSNs, in: Proceedings of the First IEEE/ACM Workshop on QoS and Security in Wireless Networks (Q2SWinet 2005), 2005, pp. 71–78].     

Performance modeling of beaconless forwarding strategies in multi-hop wireless networks

Recently, routing protocols for mobile ad hoc networks (MANETs), which use position information to improve their efficiency, have been actively studied. In this paper, we develop a mathematical model to evaluate the performance of the beaconless routing algorithm (BLR). We also propose a new forwarding strategy named distance-aware forwarding (DAF) and compare the performance of DAF with that of the traditional strategy referred to as most forwarding within radius (MFR).BLR can efficiently reduce redundancy in its transmissions for flooding. When a node receives a packet, a time variable referred to as deferring time is calculated using the positions of the sender, receiver, and final destination of the packet. Each node forwards the packet after this deferring time unless it notices that another node forwards the same packet during the deferring time. As a result, only the node that is assigned the shortest deferring time forwards the packet. It is important to make this deferring time as short as possible to reduce the total deferring time in a multi-hop transmission.Numerical results demonstrate that the proposed strategy reduces the total deferring time in a multi-hop transmission, although the number of hops slightly increases. We also make a performance analysis considering packet collisions and suggest an implementation guideline of the transmission range.     

改进的分布式QoS路由算法

拥塞网络中连接时延和请求接纳率是一对矛盾。该文在现有分布式QoS路由算法的基础上，提出一种兼顾二者的改进算法。在中间节点转发请求包时，根据累计时延进行转发测试，减少了通信复杂度。在目的节点，根据一定策略从可行路径中选择最优路径发回应答。计算机模拟显示，该算法在拥塞网络中有较低的连接时延和较高的请求接纳率。     

改进的ZigBee树路由算法

ZigBee树路由被广泛应用于多种领域,其特点是源节点向目的节点发送数据包时不需要路由表从而减少系统开销。树路由必须沿着树型拓扑发送数据,数据发送的路径往往不是最优的,这就造成了一定的局限性。提出一种基于邻居表的树路由算法,节点发送数据时通过查询邻居节点信息来计算下一跳地址。实验结果表明,改进算法在一定程度上解决原有树路由算法不灵活的缺点,提高了路由效率。     

A generalized greedy routing algorithm for 2-connected graphs

Geometric routing by using virtual locations is an elegant way for solving network routing problems. In its simplest form, greedy routing, a message is simply forwarded to a neighbor that is closer to the destination. One main drawback of this approach is that the coordinates of the virtual locations require Ω(nlogn) bits to represent, which makes this scheme infeasible in some applications.The essence of the geometric routing is the following: When an origin vertex u wants to send a message to a destination vertex w, it forwards the message to a neighbor t, solely based on the location information of u,w and all neighbors of u. In the greedy routing scheme, the decision is based on decreasing distance. For this idea to work, however, the decision needs not be based on decreasing distance. As long as the decision is made locally, this scheme will work fine.In this paper, we introduce a version of greedy routing which we call generalized greedy routing algorithm. Instead of relying on decreasing distance, a generalized greedy routing algorithm uses other criteria to determine routing paths, solely based on local information. We present simple generalized greedy routing algorithms based on st-coordinates (consisting of two integers between 0 and n−1), which are derived from an st-orientation of a 2-connected plane graph. We also generalize this result to arbitrary trees. Both algorithms are natural and simple to be implemented.     

一种满足剩余能量约束的方向性Ad Hoc网络路由协议

本文提出一种基于剩余能量约束的方向性路由协议ED-AODV。该协议首先控制RREQ分组进行方向性传输来减小网络的洪泛负担;其次,提出基于剩余能量的预警机制,当移动节点剩余能量低于报警阈值时,通知源节点提前主动进行路由选择来提高路由的稳定性。ED-AODV采用的方向性控制RREO分组转发的方法又消除了提前进行路由选择带来的洪泛负担。仿真实验结果表明,在能量有限的情况下,采用ED-AODV协议在平均端到端时延、分组投递率性能指标上均优于AODV协议。     

基于路由长度的多径路由协议

针对单径路由协议在高速Ad hoc网络中平均端到端时延和丢包率高的问题,在动态源路由协议的基础上,提出基于邻居节点变化率与路由长度的多径路由协议DSR_HD。利用HELLO消息获得一跳范围内可用邻居数,根据邻居数求得节点的邻居节点变化率。在路由发现过程中,采用路由距离与路由跳数相结合的方法计算路由长度,并选择邻居节点变化率和路由长度低的节点加入路由,从而提高路由的稳定性。仿真实验结果显示,DSR_HD协议可以有效减少数据分组传输的端到端时延及路由开销,提高分组成功投递率。     

一种基于旁听的机会网络路由算法

针对基于议价博弈的概率路由算法存在消息传送成功率提升偏慢、开销大、节点无序情况下竞争信道引起碰撞以及节点在多邻居状态下存在冗余交互的问题,提出一种基于旁听的机会网络路由算法—ORON。ORON算法通过旁听邻居节点信息,设计博弈策略使激励相容,节点对邻居与自身的交易状态进行分析,选择最佳策略,使得网络性能得到提升。仿真验证了ORON算法设计的有效性,结果表明：与基于议价博弈的现有路由算法GSCP相比,ORON算法的吞吐量和消息传送成功率至少提高了6.72%,而控制开销和平均端到端消息时延则分别降低了20%和3.55%以上。     

ZigBee网络Cluster-Tree优化路由算法研究

通过分析ZigBee协议中Cluster-Tree和AODVjr算法的优缺点,提出一种基于Cluster-Tree+AODVjr的优化路由算法。该算法利用ZigBee协议中的邻居表,通过定义分区来确定目的节点的范围,从而控制广播RREQ分组的跳数,防止无效的RREQ泛洪。此优化算法能够有效地减小路由跳数,缩短传输时延,减少网络中死亡节点的数量,提高数据传送的成功率。     

An efficient network-wide broadcasting based on hop-limited shortest-path trees

We propose a technique for reducing the number of message duplicates during network-wide broadcasting in wired networks. The key feature of our proposal is that each node keeps the information on hop-limited shortest path trees whose roots are within a certain number of hops from each node. When receiving the message, each node generates its duplicates and forwards them to a subset of neighbors, which are on the hop-limited shortest path tree rooted at the message source. The information on hop-limited shortest path trees is stored in message forwarding table of each node. We show that the hop-limited shortest path tree can be constructed in a fully-distributed manner by simply using dummy message flooding or exchanging distance vectors with poisoned reverse. Our proposal can largely reduce the number of message duplicates compared with the flooding while it is more scalable than the global-shortest-path-tree-based delivery. We also note that it guarantees the full reachability in static conditions and the time to reach of the proposal is the same as that of the flooding or the global-shortest-path-tree-based delivery. Duplicate reduction effect of our proposal is theoretically evaluated and numerically examined by simulation experiments.     

Impact of noise and interference on probabilistic broadcast schemes in mobile ad-hoc networks

Broadcasting is a vital part of on-demand routing protocols to discover new routes in mobile ad-hoc networks (MANET). Pure flooding is the earliest and still widely used mechanism of broadcasting for route discovery in on-demand routing protocol. In pure flooding, a source node broadcasts a route request to its neighbors. These neighbors then rebroadcast the received route request to their neighbors until the route request arrives at the destination node. Pure flooding may generate excessive redundant traffic leading to increased contention and collisions deteriorating the performance. To limit the redundant traffic, a number of probabilistic broadcast schemes have been proposed in the literature. However, the performance of those probabilistic broadcasting schemes is questionable under real life MANETs which are noisy in nature. Environmental factors like thermal noise and co-channel interference may have adverse effects on the system performance. This paper investigates the effects of thermal noise and co-channel interference on the performance of probabilistic schemes employed in the route discovery mechanism in MANETs. Based on extensive ns-2 simulations, this paper discovers that, contrary to the findings of previous studies, these schemes do not outperform pure flooding scheme when thermal noise and co-channel interference are taken into account.     

无线自组网中多径与单径路由的吞吐量

多径路由是无线Ad Hoc网络中一种重要的路由算法,采用多径可以增大源节点到目的节点的业务流吞吐量。该文分析无线Ad Hoc网络中多径路由的吞吐量,仿真结果表明,当源节点与目的节点之间距离较大时,多径路由的吞吐量大于单径路由,且吞吐量随跳数的增减发生缓慢变化。     

高动态航空自组网中考虑优先级的逐跳路由协议

针对航空自组网频繁的拓扑变化、网络断开的问题,提出一种考虑优先级的逐跳路由（priority concern hop-by-hop routing,PCHHR）协议。PCHHR依据运动方向优先、距离次之的原则选择下一跳路由节点,优先选择向目的节点运动的邻居作为下一跳节点,次优选择距离目的节点最近的邻居作为下一跳节点;区分数据报文的时延需求,优先转发时延约束小的数据。仿真结果表明,PCHHR在较低的控制开销和端到端时延下,总体数据分组投递率高于航空路由协议（aeronautical routing protocol,AeroRP）、贪婪转发路由和传统的端到端路由协议,提高了高实时性数据分组的投递率。     

基于改进的洪泛广播和粒子滤波的无线传感器网络节点定位

针对目前移动无线传感器网络定位问题存在的不足,提出了一种基于改进的洪泛广播机制和粒子滤波的节点定位算法。对于一个给定的未知节点,首先采用改进的洪泛广播机制,从离它最近的锚节点得到的有效平均跳距来计算出它到它的所有邻居节点的距离。然后采用一种差分误差校正算法,以减小平均跳距中由于多跳累积造成的测量误差;其次,采用粒子滤波和虚拟锚节点来减小预测区域,得到更有效的粒子预测区域,从而进一步减小对未知节点位置的估计误差。仿真结果表明,所提算法与定位算法DV-Hop、蒙特卡罗Baggio（MCB）和基于测试的蒙特卡罗定位（MCL）相比,能够有效地抑制冗余广播和减小与节点定位相关的消息开销,以较低的通信成本实现较高精度的定位性能。     

WSN中基于树型标号系统的分布式路由算法

针对无线传感器网络中数据中心存储的路由问题,提出一种基于树型标号系统的分布式路由算法。将网络中的节点组织成以参考节点为根的树型结构,通过比较目的节点标号与邻居节点标号,选择转发节点,实现数据路由。分析与仿真结果表明,该路由算法的空间开销较低、路由效率较高,并且生成的路径接近最短路径。     

三维AD-HOC 网络地理信息路由算法

在二维AD-HOC 网络中,可以充分利用节点的地理信息进行路由,即AD-HOC 中节点根据邻居节点的距离目标节点的距离,选择下一跳节点进行路由转发.由于AD-HOC 中节点部署通常不满足均匀分布,造成网络中出现路由空洞,贪婪转发算法在遭遇空洞的情况下将无法正确执行.在二维AD-HOC 网络环境中,往往采用贪婪(Greedy)算法结合表面路由(Face Routing)的方法跳出路由空洞.但是在三维条件下,目前没有很好跳出路由空洞的算法能够实现有效的路由.提出了一种在三维AD-HOC 网络中的地理信息路由算法GSG,该算法使用3D RDT 图和3D RRNG 图的方法实现三维网络空间的划分.采用3D 表面路由的方法进行信息传递,在遭遇局部最小点时,可有效跳出路由空洞.仿真实验结果表明,GSG 算法可提升三维AD-HOC 网络条件下地理信息路由的效率,具有良好的可扩展性.