SmallWorld Model-Based Polylogarithmic Routing Using Mobile Nodes

The use of mobile nodes to improve network system performance has drawn considerable attention recently. The movement-assisted model considers mobility as a desirable feature,where routing is based on the store-carry-forward paradigm with random or controlled movement of resource rich mobile nodes.The application of such a model has been used in several emerging networks,including mobile ad hoc networks(MANETs),wireless sensor networks(WSNs),and delay tolerant networks(DTNs).It is well known that mobility increases the capacity of MANETs by reducing the number of relays for routing,prolonging the lifespan of WSNs by using mobile nodes in place of bottleneck static sensors,and ensuring network connectivity in DTNs using mobile nodes to connect different parts of a disconnected network.Trajectory planning and the coordination of mobile nodes are two important design issues aiming to optimize or balance several measures, including delay,average number of relays,and moving distance.In this paper,we propose a new controlled mobility model with an expected polylogarithmic number of relays to achieve a good balance among several contradictory goals,including delay,the number of relays,and moving distance.The model is based on the small-world model where each static node has"short"link connections to its nearest neighbors and"long"link connections to other nodes following a certain probability distribution.Short links are regular wireless connections whereas long links are implemented using mobile nodes.Various issues are considered,including trade-offs between delay and average number of relays,selection of the number of mobile nodes,and selection of the number of long links.The effectiveness of the proposed model is evaluated analytically as well as through simulation.     

Error analysis in accelerated session-level MANET simulations

Simulation investigations form a vital part of networking research, and have long been used by the research community interested in mobile ad hoc networks (MANETs) to design protocols and to evaluate quality of service mechanisms. Many MANET simulators developed so far model the network with high granularity in order to ensure the accuracy of the simulation results. But those tools are often too computationally expensive to simulate large-scale MANETs. This paper reports a new session-level MANET simulator and develops an error analysis approach which uniquely allows for optimal parameterization of the time-stepping simulation methods. The novelty lies in broadening the simulation acceleration method, model abstraction, to MANET simulation. At the same time the methodological challenges of validation are addressed through both analytical and experimental approaches. The proposed techniques were implemented in SSIM, a session-level simulator for MANETs. The experimental results show that the proposed accelerated simulation solution achieves significant acceleration by reducing the number of events, and the wall-clock simulation time, while retaining excellent accuracy.     

基于NS-2的MANET网络路由协议DSR性能研究

移动Ad hoc网络(MANET)是一组无线主机组成的没有任何建立好的基础设施的临时网络,网络拓扑高度变化自组织网络,由于其特点的限制,路由协议是其组网的关键技术和具有挑战性的问题之一,本文研究了典型的路由协议DSR的工作原理,设计了在NS-2中的仿真场景来研究分析DSR路由协议的性能和在移动网络环境中的适应性。对Ad hoc的组网和后续协议的研究具有指导意义。     

MESHMdl event spaces — A coordination middleware for self-organizing applications in ad hoc networks

Mobile ad hoc networks (MANETs) are gaining importance as a promising technology for flexible, proximity-based, mobile communication. However, the inherent dynamics of MANETs imposes strong limitations on the design of distributed applications. They need to be able to adapt to changing conditions quickly and organize themselves in terms of component placement and communication habits. In this paper, we present MESHMdl, a middleware that provides a high level of awareness and decoupling for application components to make them more flexible and adaptable. We focus on the Event Space as the central communication medium of MESHMdl. The Event Space offers a simple, unified communication interface for inter-agent communication as well as for communication with the middleware and resource access. Furthermore, it serves as a means for flexibly extending a MESHMdl daemon. We investigate the performance of the Event Space on different mobile devices and show that it is superior to comparable systems.     

Two-tier authentication for cluster and individual sets in mobile ad hoc networks

Mobile ad hoc networks (MANETs) have been proposed as an extremely flexible technology for establishing wireless communications. In comparison with fixed networks or traditional mobile cellular networks, some new security issues have arisen with the introduction of MANETs. Routing security, in particular, is an important and complicated issue. In this work, we propose a two-tier authentication scheme for cluster and individual sets, in MANETs. The first tier, based on a hash function and the MAC concept, provides fast message verification and group identification. The second tier, based on secret sharing technology, provides secure user identification. The scenario of two-tier authentication can prevent internal and external attacks, including black holes, impersonation, routing table overflows and energy consummation attacks.     

Discovering timely information in MANETs

Timely information refers to information whose ‘most recent’ or ‘latest’ instance is most valuable. In mobile ad hoc networks (MANETs), multiple instances of a piece of timely information may be produced by different nodes at different points in time. The problem is to discover the ‘latest’ instance among all existing instances. Within the context of MANETs, timely information discovery is fundamentally different from the existing resource/service discovery problem whose goal is to discover either any instance or a subset of instances which satisfy a local query constraint that can be specified and evaluated using only local attributes of each individual node. In contrast, the timely information discovery problem imposes the global (timeliness) constraint which should best be evaluated when all the instances are considered to determine the latest instance. The complication of discovering timely information arises from the existence of multiple instances of the information, which are produced at different points in time by different nodes in the network, and the need to collect all these instances to decide the latest instance. For MANETs, the lack of infrastructure supports, frequent topology changes, and potential packet loss in wireless communications further challenge the problem of timely information discovery. This paper describes a self-organizing, peer-to-peer based approach, termed ALADIN, to discovering timely information in MANETs. In ALADIN, nodes that produce instances of the timely information are peers who self-organize an adaptive and distributed ‘search infrastructure’ to facilitate the discovery of the latest instance. A simulation study shows that ALADIN is scalable without incurring network-wide flooding in the case of large-scale networks and popular timely information, and yields a high chance of discovering the latest instance in the presence of mobility.     

Transient chaotic neural network-based disjoint multipath routing for mobile ad-hoc networks

Due to mobility of wireless hosts, routing in mobile ad-hoc networks (MANETs) is a challenging task. Multipath routing is employed to provide reliable communication, load balancing, and improving quality of service of MANETs. Multiple paths are selected to be node-disjoint or link-disjoint to improve transmission reliability. However, selecting an optimal disjoint multipath set is an NP-complete problem. Neural networks are powerful tools for a wide variety of combinatorial optimization problems. In this study, a transient chaotic neural network (TCNN) is presented as multipath routing algorithm in MANETs. Each node in the network can be equipped with a neural network, and all the network nodes can be trained and used to obtain optimal or sub-optimal high reliable disjoint paths. This algorithm can find both node-disjoint and link-disjoint paths with no extra overhead. The simulation results show that the proposed method can find the high reliable disjoint path set in MANETs. In this paper, the performance of the proposed algorithm is compared to the shortest path algorithm, disjoint path set selection protocol algorithm, and Hopfield neural network (HNN)-based model. Experimental results show that the disjoint path set reliability of the proposed algorithm is up to 4.5 times more than the shortest path reliability. Also, the proposed algorithm has better performance in both reliability and the number of paths and shows up to 56% improvement in path set reliability and up to 20% improvement in the number of paths in the path set. The proposed TCNN-based algorithm also selects more reliable paths as compared to HNN-based algorithm in less number of iterations.     

一个新的分布式最小连通支配集近似算法

在计算机网络中广泛使用广播来解决一些网络问题,设计有效的广播算法是一项重要的课题。文中提出一种分布地计算网络最小连通支配集的近似算法并给出了它的正确性证明。它只需要网络节点具有局部的网络状态信息,可伸缩性强。通过此算法可以在网络中自动形成一个虚拟骨干网,从而可为网络中的广播和路由操作提供一个有效的通信基础。模拟结果表明,文中提出的算法求得的连通支配集小,能较好地应用于一般网络以及移动自组网络中。     

Video transmission enhancement in presence of misbehaving nodes in MANETs

Mobile Ad-hoc NETworks (MANET) are infrastructureless networks where self-configuring mobile nodes are connected by wireless links. Because of its decentralized operation, these nodes rely on each other to store and forward packets. Video transmission over MANETs is more challenging than over conventional wireless networks due to rapid topology changes and lack of central administration. Most of the proposed MANET protocols assume that all nodes are working within a cooperative and friendly network context. However, misbehaving nodes that exhibit abnormal behaviors can disrupt the network operation and affect the network availability by refusing to cooperate to route packets due to their selfish or malicious behavior. In this paper, we examine the effect of packet dropping attacks on video transmission over MANETs. We also study the effects of mitigation using intrusion detection systems to MANET in presence of video traffic. To the best of our knowledge, this is the first attempt to study multimedia over such environments. We propose a novel intrusion detection system, which is an adaptive acknowledgment scheme (AACK) with the ability to detect misbehaved nodes and avoid them in other transmissions. The aim of AACK scheme is to overcome watchdog weaknesses due to collisions and limited transmission power and also to improve TWOACK scheme. To demonstrate the performance of our proposed scheme, simulation experiments are performed. The results of our experiments show that MPEG4 is more suitable for our simulation environment than H264 video traffic. The simulation results show that AACK scheme provides better network performance with less overhead than other schemes; it also shows that AACK outperforms both TWOACK and watchdog in video transmission applications in the presence of misbehaving nodes.     

A cooperative CDMA-based multi-channel MAC protocol for mobile ad hoc networks

In this paper, we present CCM-MAC, a cooperative CDMA-based multi-channel medium access control (MAC) protocol for mobile ad hoc networks (MANETs) in which each node has one half-duplex transceiver. The protocol mitigates the multi-channel hidden and exposed terminal problems by using information about channel usage gleaned from overhearing (cooperating) neighbours. By accounting for the multiple access interference, CCM-MAC also addresses the near-far problem of CDMA in MANETs enabling concurrent transmissions on each channel. We provide an analysis of the maximum throughput of CCM-MAC and validate it through simulation in Matlab. We also compare the throughput it achieves to IEEE 802.11, a multi-channel MAC protocol, and a CDMA-based MAC protocol.     

MANET路由协议及其性能研究

MANET(Mobile Ad Hoe Network)是由一组无线移动主机组成的一个没有任何建立好的基础设施或集中管理设备的临时网络。网络拓扑易变、带宽、能源有限是Ad Hoc移动网络的主要特点。重点介绍了Ad hoc网络的组网关键技术——路由协议，并对现在的具有代表性的协议性能进行了比较，研究了在不同环境下的各自路由协议仿真实验所体现出来的性能差别，对Ad hoc的组网具有指导意义。     

Modelling and simulation of Rayleigh fading,path loss,and shadowing fading for wireless mobile networks

In this paper, we first derive two explicit mathematical expressions of bit error rates (BERs) with Rayleigh fading for differential phase shift keying (DPSK) and quadrature amplitude modulation (QAM), and establish corresponding simulation models to realize the effect of Rayleigh fading. Next, we propose a mathematical expression to define the effect of shadowing fading and an approach to computing it. Then, we optimize the effect of path loss through adapting the value of the path loss exponent to different environments. Finally, using a packet-oriented simulation tool, OPtimized Network Engineering Tool (OPNET), we realize the effects of Rayleigh fading and shadowing fading, optimize the effect of path loss, and investigate the integrated impact of these effects on the performance of wireless mobile networks including wireless local area networks (WLANs) and mobile ad hoc networks (MANETs). Simulation results not only coincide with the experimental results in present literature, but also show that these effects exert a non-negligible impact on the performance of wireless mobile networks. Accordingly, our new models and approaches make the present over-optimistic simulation results more accurate and reasonable.     

Logarithmic Store-Carry-Forward Routing in Mobile Ad Hoc Networks

Two schools of thought exist in terms of handling mobility in mobile ad hoc networks (MANETs). One is the traditional connection-based model, which views node mobility as undesirable and tries to either remove (through recovery schemes) or mask (through tolerant schemes) the effect of mobility. The other is the mobility-assisted model, which considers mobility as a desirable feature, where routing is based on the store-carry-forward paradigm with random or controlled movement of mobile nodes (called ferries). It is well known that mobility increases the capacity of MANETs by reducing the number of relays in routing. Surprisingly, only two models, diameter hop count in the connection-based model and constant hop count in the mobility-assisted model, which correspond to two extremes of the spectrum, have been systematically studied. In this paper, we propose a new routing model that deals with message routing, as well as trajectory planning, of the ferries that carry the message. A logarithmic number of relays are enforced to achieve a good balance among several contradictory goals, including increasing network capacity, increasing ferry sharing, and reducing moving distance. The model considers the dynamic control of ferries in terms of the number of ferries, trajectory planning of ferries, and node communication and synchronization. The effectiveness of the proposed model is evaluated analytically, as well as through simulation     

A Mechanism for Communication-Efficient Broadcast Encryption over Wireless Ad Hoc Networks

Due to its low communication cost, stateful broadcast encryption is an appealing solution for secure content distribution in mobile ad hoc wireless networks (MANETs). Unfortunately, the inherent limitations of MANETs prevent a standard application of such schemes since they require receivers to be online. In this paper, we present a reliable message delivery mechanism for MANETs that is based on erasure codes and that leverages node mobility in order to achieve non-interactive recovery of missed messages. We then show how our mechanism can be used to reliably deliver the key updates of a stateful broadcast encryption scheme. Our solution has several useful properties: it allows trade-offs between the amount of storage required at each node and the speed of message recovery; and it has the ability to leverage the resources of unauthorized nodes. We evaluate the performance of our approach through simulation, and show that it achieves good performance for networks with high node density.     

E-D2HCP: enhanced distributed dynamic host configuration protocol

Mobile Ad Hoc Networks (MANETs) consist of mobile nodes equipped with wireless devices. They do not need any kind of pre-existent infrastructure and are about self-managed networks. MANETs enable communication between mobile nodes without direct links and across multihop paths. To ensure correct operation of the routing protocols, MANETs, have to assign unique IP addresses to the MANET devices. Furthermore, the address assignment is an important issue when dealing with MANET networks because the traditional approaches are not applicable without some changes, having to provide new protocols for the address auto-configuration. These schemes must take into account the properties of MANETs such as dynamic topology, limited resources or lack of infrastructure. In this paper, we propose a stateful scheme for dynamic allocation of IP addresses in MANETs entitled Extended Distributed Dynamic Host Configuration Protocol because it is based on a previous piece of work (D2CHP). This extension includes the network merging not covered by its predecessor. Simulation results show that the new protocol also improves D2HCP functionality in areas such as fault tolerance, concurrency and latency.     

QMRPRNS: Design of QoS multicast routing protocol using reliable node selection scheme for MANETs

A mobile Ad-Hoc networks (MANETs) is a continuously self-configuring, infrastructure-less network of wireless mobile devices. In which multicast is one of the efficient way of communication. Currently, several research have been conducted to design multicast routing protocols for wireless mobile ad-hoc networks (MANETs). Multicasting is a technique that allow to send the same message to a group of destinations simultaneously. However, it faces several challenges against its implementation in ad-hoc network due to its dynamic nature, lack of bandwidth, short battery lifetime of the mobile devices. The multicast routing protocol MAODV have several constraints as mentioned above. Hence to address these constraints a reliable neighbour nodes selection scheme has been integrated over MAODV. This paper attempt a Quality of Service (QoS) based multicast routing protocol using reliable neighbour nodes selection scheme (QMRPRNS) for same. The simulation has been conducted to compare the performance of the proposed scheme against some existing multicast routing protocols which shows significant improvement over EMAODV and MAODV.     

A token based distributed algorithm for supporting mutual exclusion in opportunistic networks

Opportunistic networks are essentially distributed networks with transient connectivity among nodes. Nodes in opportunistic networks are resource constrained, mobile and opportunistically come in contact with each other. In such a distributed network, nodes may require exclusive access to a shared object or resource. Ensuring freedom from starvation is a challenging problem in opportunistic networks due to limited pairwise connectivity and node failures. In this paper, we review mutual exclusion algorithms proposed for generic mobile ad hoc networks (MANETs) and discuss their applicability to opportunistic networks. Further, we propose a novel token based algorithm¹ and prove its correctness. Simulation results show that our algorithm is communication efficient as compared to other algorithms proposed for generic mobile ad hoc networks. We also propose a timeout based fault detection algorithm that exploits the intercontact time distributions.     

A distributed fault identification protocol for wireless and mobile ad hoc networks

This paper considers the problem of self-diagnosis of wireless and mobile ad hoc networks (MANETs) using the comparison approach. In this approach, a network (MANET) consists of a collection of n   independent heterogeneous mobile or stationary hosts interconnected via wireless links, and it is assumed that at most σ$\sigma$ of these hosts are faulty. In order to diagnose the state of the MANET, tasks are assigned to pairs of hosts and the outcomes of these tasks are compared. The agreements and disagreements between the hosts are the basis for identifying the faulty ones. The comparison approach is believed to be one of the most practical fault identification approaches for diagnosing hard and soft faults. We develop a new distributed self-diagnosis protocol, called Dynamic-DSDP, for MANETs that identifies both hard and soft faults in a finite amount of time. The protocol is constructed on top of a reliable multi-hop architecture. Correctness and complexity proofs are provided and they show that our Dynamic-DSDP performs better, from a communication complexity viewpoint, than the existing protocols. We have also developed a simulator, that is scalable to a large number of nodes. Using the simulator, we carried out a simulation study to analyze the effectiveness of the self-diagnosis protocol and its performance with regards to the number of faulty hosts. The simulation results show that the proposed approach is an attractive and viable alternative or addition to present fault diagnosis techniques in MANET environments.     

移动自组网中基于多约束和协同过滤动态信任机制*

由于具有分布式特性,导致移动自组网容易遭受攻击。为了增强移动自组网的安全性,建立一套适合自组织、无认证中心的节点信任评估模型是非常必要的。因此,提出了一种移动自组网中基于多约束和协同过滤的动态信任机制。其主要思想是在根据节点自身的经历的基础上,采用一个带多约束的信任更新算法来评估直接信任。其中：时间衰减因子保证了信任度随时间进行衰减;奖励因子保证了良好的节点应受到奖励;惩罚因子保证了恶意节点应受到惩罚。另外,采用协同过滤技术来评估推荐信任,以此来阻止不诚实的推荐。通过定量评估分析和模拟仿真,结果表明所提出的方法比Bayesian模型能更精确地计算节点之间的信任度和提高移动自组网的安全性。