一种面向移动Ad Hoc网络DSR协议的改进泛洪算法

在移动自组织网络中,基于移动节点地理位置辅助信息,提出了一种新的泛洪算法——位置辅助泛洪改进算法（ILFA）,ILFA通过节点位置信息重传广播分组并有效控制网络流量。此外,将ILFA应用于经典MANET源路由（dynamic source routing,DSR）协议中,通过限定请求区域和期望区域等限制路由发现的有效范围,进而通过设置提名广播重传邻居列表限定路由请求分组重传范围,有效减小DSR路由寻路分组的传播次数。仿真结果证明,和传统泛洪方案相比,ILFA能够有效减小DSR路由协议的路由开销并提升MANET吞吐量。     

The Broadcast Storm Problem in a Mobile Ad Hoc Network

Broadcasting is a common operation in a network to resolve many issues. In a mobile ad hoc network (MANET) in particular, due to host mobility, such operations are expected to be executed more frequently (such as finding a route to a particular host, paging a particular host, and sending an alarm signal). Because radio signals are likely to overlap with others in a geographical area, a straightforward broadcasting by flooding is usually very costly and will result in serious redundancy, contention, and collision, to which we call the broadcast storm problem. In this paper, we identify this problem by showing how serious it is through analyses and simulations. We propose several schemes to reduce redundant rebroadcasts and differentiate timing of rebroadcasts to alleviate this problem. Simulation results are presented, which show different levels of improvement over the basic flooding approach.     

一种抑制MANET网关洪泛策略

在MANET子网互连架构中,其网关发现采用洪泛通告报文的方式,所形成的广播风暴引起较大控制开销。由此提出一种动态自适应网关发现协议,该协议可根据MANET的移动节点信息自适应设置网关通告报文GWADV的TTL值和发送间隔,同时采用基于距离门限的动态计数DDC网关洪泛通告报文抑制策略。仿真结果表明,该协议可以有效地应对网关洪泛通告报文的问题,在保持较高分组投递率的同时,能够减小时延和控制开销。     

MANET中一种新的广播风暴抑制算法

为了解决简单的洪泛式广播所引起的广播风暴问题,提出了一种新的抑制算法。算法将结点的传输覆盖范围分成三个区域,对于不同区域内的广播消息采用不同的转发机制。仿真结果显示该算法在转发路由请求报文数、端到端延迟时间和数据吞吐量等方面要优于其他各种广播算法。     

DBLAR：A DISTANCE-BASED LOCATION-AIDED ROUTING FOR MANET

In location-aided routing of Mobile Ad hoc NETworks (MANET), nodes mobility and the inaccuracy of location information may result in constant flooding, which will reduce the network performance. In this paper, a Distance-Based Location-Aided Routing (DBLAR) for MANET has been proposed. By tracing the location information of destination nodes and referring to distance change between nodes to adjust route discovery dynamically, the proposed routing algorithm can avoid flooding in the whole networks. Besides, Distance Update Threshold (DUT) is set up to reach the balance between real-time ability and update overhead of location information of nodes, meanwhile, the detection of relative distance vector can achieve the goal of adjusting forwarding condition. Simulation results reveal that DBLAR performs better than LAR1 in terms of packet successful delivery ratio, average end-to-end delay and routing-load, and the set of DUT and relative distance vector has a significant impact on this algorithm.     

Adaptive gossip protocols: Managing security and redundancy in dense ad hoc networks

Many ad hoc routing algorithms rely on broadcast flooding for location discovery or, more generally, for secure routing applications. Flooding is a robust algorithm but because of its extreme redundancy, it is impractical in dense networks. Indeed in large wireless networks, the use of flooding algorithms may lead to broadcast storms where the number of collisions is so large that it causes system failure. To prevent broadcast storms, many mechanisms that reduce redundant transmissions have been proposed that reduce retransmission overhead either deterministically or probabilistically.Gossip is a probabilistic algorithm in which packet retransmission is based on the outcome of coin tosses. The retransmission probability can be fixed, dynamic or adaptive. With dynamic gossip, local information is used to determine the retransmission probability. With adaptive gossip, the decision to relay is adjusted adaptively based on the outcome of coin tosses, the local network structure, and the local response to the flooding call. The goal of gossip is to minimize the number of retransmissions, while retaining the main benefits of flooding, e.g., universal coverage, minimal state retention, and path length preservation.In this paper we consider ways to reduce the number of redundant transmissions in flooding while guaranteeing security. We present several new gossip protocols that exploit local connectivity to adaptively correct propagation failures and protect against Byzantine attacks. A main contribution of this work is that we introduce a cell-grid approach that allows us to analytically prove performance and security protocol properties. The last two gossip protocols that we give are fully adaptive, i.e., they automatically correct all faults and guarantee delivery, the first such protocols to the best of our knowledge.     

Bandwidth-satisfied multicast trees in large-scale ad-hoc networks

The purpose of this paper is to construct bandwidth-satisfied multicast trees for QoS applications in large-scale ad-hoc networks (MANETs). Recent routing protocols and multicast protocols in large-scale MANETs adopt two-tier infrastructures to avoid the inefficiency of the flooding. Hosts with a maximal number of neighbors are often chosen as backbone hosts (BHs) to forward packets. Most likely, these BHs will be traffic concentrations/bottlenecks of the network. In addition, since host mobility is not taken into consideration in BH selection, these two-tier schemes will suffer from more lost packets if highly mobile hosts are selected as BHs. In this paper, a new multicast protocol is proposed for partitioning large-scale MANET into two-tier infrastructures. In the proposed two-tier multicast protocol, hosts with fewer hops and longer remaining connection time to the other hosts will be selected as BHs. The objective is not only to obtain short and stable multicast routes, but also to construct a stable two-tier infrastructure with fewer lost packets. Further, previous MANET quality-of-service (QoS) routing/multicasting protocols determined bandwidth-satisfied routes for QoS applications. Some are implemented as a probing scheme, but the scheme is inefficient due to high overhead and slow response. On the contrary, the others are implemented by taking advantage of routing and link information to reduce the inefficiency. However, the latter scheme suffers from two bandwidth-violation problems. In this paper, a novel algorithm is proposed to avoid the two problems, and it is integrated with the proposed two-tier multicast protocol to construct bandwidth-satisfied multicast trees for QoS applications in large-scale MANETs. The proposed algorithm aims to achieve better network performance by minimizing the number of forwarders in a tree.     

Relative degree adaptive flooding broadcast algorithm for ad hoc networks

Broadcasting has been widely used in mobile Ad hoc networks as a communication means to disseminate information to all reachable nodes. Because radio signals are likely to overlap with others in a geographical area, straightforward broadcasting by flooding becomes very costly and results in serious redundancy, contention and collision, to which we refer as the broadcast storm problem. In this paper we propose the Relative Degree Adaptive flooding Broadcast (RDAB) algorithm for Ad hoc networks to efficiently reduce the broadcast overhead in the network. Based on the current situation of the network and the degree of the nodes, RDAB calculates the relative degree of the nodes, decides which nodes need to re-transmit and which nodes only need to receive. The higher the neighbor node's relative degree, the more uncovered nodes it can cover, hence these nodes can be selected to re-transmit broadcasting packets in the networks. We analyze the reliability and the validity of the RDAB algorithm to prove that the RDAB algorithm is a valid flooding broadcast algorithm. Simulation results show that the RDAB strategy outperforms the Ordinary Flooding Broadcast Method (OBM) and the Multipoint Relaying (MPR) protocol for Ad hoc networks.     

RPSF: A Routing Protocol with Selective Forwarding for Mobile Ad-Hoc Networks

Many existing reactive routing algorithms for mobile ad-hoc networks use a simple broadcasting mechanism for route discovery which can lead to a high redundancy of route-request messages, contention, and collision. Position-based routing algorithms address this problem but require every node to know the position and velocity of every other node at some point in time so that route requests can be propagated towards the destination without flooding the entire network. In a general ad-hoc network, each node maintaining the position information of every other node is expensive or impossible. In this paper, we propose a routing algorithm that addresses these drawbacks. Our algorithm, based on one-hop neighborhood information, allows each node to select a subset of its neighbors to forward route requests. This algorithm greatly reduces the number of route-request packets transmitted in the route-discovery process. We compare the performance of our algorithm with the well known Ad-hoc On-demand Distance Vector (AODV) routing algorithm. On average, our algorithm needs less than 12.6% of the routing-control packets needed by AODV. Simulation results also show that our algorithm has a higher packet-delivery ratio and lower average end-to-end delay than AODV.     

低开销的MANET网络按需路由协议

针对简单泛洪效率低的问题,提出了一个限制洪泛的高效的路由广播算法,通过Euclidean距离来限制路由发现过程中请求分组被转发的次数;研究了减少路由维护开销,并降低路由发现的频率的方法,提出了一个基于节点高度的路由修复与优化算法,该算法使用节点监听来对链路断裂的路由进行修复与优化.基于限制泛洪的高效的路由广播算法和路由修复优化算法,提出了一种新的低开销的MANET网络按需路由协议LOOR(low overhead on-demand routing).仿真结果表明,新协议增强了路由的顽健性,减少了路由跳数,降低了路由发现的频率,提高了数据分组递送率,并显著地降低了路由控制开销.     

SDR: A Stable Direction-Based Routing for Vehicular Ad Hoc Networks

A stable and reliable routing mechanism for vehicular ad hoc networks (VANETs) is an important step toward the provision of long data transmission applications, such as file sharing and music download. Traditional mobile ad hoc network (MANET) routing protocols are not suitable for VANET because the mobility model and environment of VANET are different from those of traditional MANET. To solve this problem, we proposed a new stable routing algorithm, called stable directional forward routing. The novelty of the proposed routing protocol is its combining direction broadcast and path duration prediction into ad hoc on-demand distance vector routing protocols, which including: (1) Nodes in VANET are grouped based on the position, only nodes in a given direction range participating in the route discovery process to reduce the frequency of flood requests, (2) Route selection is based on the link duration while not the hops or other metrics to increase the path duration, (3) Route discovery is executed before the path expiration in order to decrease the end to end delay. The performance of the new scheme is evaluated through extensive simulations with Qualnet. Simulation results indicate the benefits of the proposed routing strategy in terms of decreasing routing control packet, reducing the number of link-breakage events, improving the packet delivery ratio and decreasing the end-to-end delay.     

Security upgrade against RREQ flooding attack by using balance index on vehicular ad hoc network

VANET is an ad hoc network that formed between vehicles. Security in VANET plays vital role. AODV routing protocol is a reactive or on-demand routing protocol which means if there is data to be send then the path will create. AODV is the most commonly used topology based routing protocol for VANET. Using of broadcast packets in the AODV route discovery phase caused it is extremely vulnerable against DOS and DDOS flooding attacks. Flooding attack is type of a denial of service attack that causes loss of network bandwidth and imposes high overhead to the network. The method proposed in this paper called Balanced AODV (B-AODV) because it expects all network node behave normally. If network nodes are out of the normal behavior (too much route request) then they identified as malicious node. B-AODV is designed with following feature: (1) The use of adaptive threshold according to network conditions and nodes behavior (balance index) (2) Not using additional routing packets to detect malicious nodes (3) Perform detection and prevention operations independently on each node (4) Perform detection and prevention operations in real time (5) No need for promiscuous mode. This method for detection and prevention flooding attack uses average and standard deviation. In this method each node is employing balance index for acceptation or rejection RREQ packets. The results of the simulation in NS2 indicates B-AODV is resilience against flooding attack and prevent loss of network bandwidth. Comparing between AODV with B-AODV in normal state (non-attacker) shows B-AODV is exactly match with AODV in network performance, this means that the B-AODV algorithm does not impose any overhead and false positive to AODV.     

SABAGAR: A Simple Attribute-Based Addressing and GPS-Aided Routing Protocol for Applications in Wireless Sensor Networks

We propose in this paper a data-centric routing protocol for wireless sensor network applications. This protocol, called SABAGAR, is designed to be implemented easily to provide the basis for commercially successful products, and to await more vendors in wireless products. Sensor nodes may have no global identifications because the number of sensors can be large, hence, attribute-based addressing and broadcast communication paradigm can be used to facilitate data acquisition. However, broadcasting simply by flooding usually results in serious redundancy and endlessly looping packets, and thus degrades the network performance. To deal with this problem, we present a position-vector-based (PVB) algorithm for the SABAGAR protocol. This paper also provides detailed simulation results to support the proposed protocol design.     

基于泛洪约束的MANET按需组播路由协议

降低路由控制开销是MANET网络组播路由协议节省节点能量,提高带宽利用率的关键因素之一。本文研究了组播路径近邻节点对路由维护的作用以及链路的连通性,分别提出了一个新的泛k-洪约束算法和一个混合泛洪模式。基于泛k-洪约束算法和混合泛洪模式,提出一个新的按需组播路由协议ODMRP-CF,ODMRP-CF协议通过选择k-路由近邻节点转发泛洪分组来提高泛洪效率。ODMRP-CF协议不仅保持了ODMRP协议所具有的简单,对节点移动鲁棒性好的优点,而且有效地降低了ODMRP-CF协议的控制开销。     

智能家居ZigBee网络的构建与路由优化

ZigBee网络技术是一项新兴的低成本、低功耗的短距离无线通信技术,在智能家居中有广阔的应用前景。介绍了智能家居中ZigBee的通讯协议和网络地址分配方法,并针对传统的AODVjr路由算法在路由过程中RREQ分组过量洪泛问题和Cluster-Tree算法只按父子关系选择路由问题,提出了一种改进路由算法。改进算法将AODVjr和Cluster-Tree算法相结合,引入邻居表,适当控制RREQ转发方向,并考虑节点最小剩余能量。仿真结果表明,改进算法可以减少路由开销,延长节点的生存时间,均衡网络负荷。     

采用定向天线的MANET邻居发现算法研究

在无线多跳移动自组织网(MANET)中采用定向天线(特别是波束成形天线)有一系列优点。这一技术能增加单跳传输的距离、减小干扰、提高空间复用度,从而能显著增大系统容量。然而,适应于采用全向天线的传统MANET的媒质接入控制(MAC)、功率控制、邻居发现、路由等方法必须作相应的修改。在分析前人相关研究的基础上,针对MANET使用定向天线情况下的邻居发现机制及算法进行了深入研究,提出了2种采用定向天线的MANET的邻居发现算法———非辅助TD模式的定向邻居发现算法与非辅助TRD模式的定向邻居发现算法。这2种算法与目前已提出的其他定向邻居发现算法的最大区别是,它们不需要依赖GPS或其他辅助信息就能独立实现邻居发现。     

一种两跳聚簇的移动自组网拓扑发现策略

基于两跳聚簇的拓扑发现策略可用于解决移动自组网中由于网络拓扑动态变化带来的拓扑发现难题。该策略使用了节点聚簇和双向链路的方法,规定只有簇头节点才能生成路由更新包,通过采用多点传递集抑制了路由更新包在网络中的泛洪;通过相邻簇的簇头协同管理,最大程度地减少了双向链路被重复报告。分析结果显示,相比于使用普通链路状态协议的拓扑发现策略,该策略消除了将近50%的拓扑发现控制负载。     

Reducing Latency and Overhead of Route Repair with Controlled Flooding

Ad hoc routing protocols that use broadcast for route discovery may be inefficient if the path between any source–destination pair is frequently broken. We propose and evaluate a simple mechanism that allows fast route repair in on demand ad hoc routing protocols. We apply our proposal to the Ad hoc On-demand Distance Vector (AODV) routing protocol. The proposed system is based on the Controlled Flooding (CF) framework, where alternative routes are established around the main original path between source–destination pairs. With alternative routing, data packets are forwarded through a secondary path without requiring the source to re-flood the whole network, as may be the case in AODV. We are interested in one-level alternative routing. We show that our proposal reduces the connection disruption probability as well as the frequency of broadcasts.     

A region-based routing protocol for wireless mobile ad hoc networks

Flooding-based route discovery is widely assumed in existing routing protocols of wireless ad hoc networks. Network-wide flooding enables the discovery of optimal routes from sources to destinations; however, as all network nodes are required to participate in the relays of route request packets, substantial control overhead is inevitable. Some efficient broadcast schemes can suppress redundant packet relays, but they often suppress the discovery of optimal routes, too. In this article we propose to dynamically create a prerouting region between each source-destination pair and limit the propagations of route request packets only within this region. The prerouting region effectively restricts route discovery activities to the nodes that most likely constitute the optimal or near-optimal routes. Consequently, not only is route construction overhead significantly reduced; route optimality is also guaranteed. The article presents a region-based routing (REGR) protocol covering both new route formation cases and route update cases. Simulations show that our protocol is particularly beneficial to dense and large-scale mobile ad hoc networks.     

A secure broadcasting scheme to provide availability,reliability and authentication for wireless sensor networks

Reliability and security of broadcasting is critical in Wireless Sensor Networks (WSNs). Since reliability and security compete for the same resources, we are interested in jointly solving for error control coding (to achieve reliability) and integrity for a broadcast scenario. We assume Byzantine attacks in which the adversary can compromise nodes and then drop (or modify) the legitimate packets or inject its own packets. For reliable and efficient multihop broadcasting, it is critical to reduce the energy consumption and latency. To prevent the adversary from consuming the scarce network resources by injecting bogus packets, each receiver node should make sure that packets it receives are authentic and it filters out malicious packets immediately. We build our authentication scheme, on top of a reliable and energy efficient broadcasting protocol called Collaborative Rateless Broadcast (CRBcast) to improve efficiency and reliability. On contrary to the previous schemes, our scheme is resilient with respect to Byzantine adversary as well as routing and flooding attacks and protocol exploits. Moreover, we compared our scheme with the previously proposed broadcast authentication schemes and showed that our scheme outperforms them in terms of efficiency and data availability. This is a crucial improvement over the previous schemes that ensure availability by flooding, introducing very large communication overhead and latency.