F-Ant: an effective routing protocol for ant colony optimization based on fuzzy logic in vehicular ad hoc networks

Vehicular ad hoc networks (VANETs) are a subset of mobile ad hoc networks that provide communication services between nearby vehicles and also between vehicles and roadside infrastructure. These networks improve road safety and accident prevention and provide entertainment for passengers of vehicles. Due to the characteristics of VANET such as self-organization, dynamic nature and fast-moving vehicles, routing in this network is a considerable challenge. Swarm intelligence algorithms (nature-inspired) such as ant colony optimization (ACO) have been proposed for developing routing protocols in VANETs. In this paper, we propose an enhanced framework for ACO protocol based on fuzzy logic for VANETs. To indicate the effectiveness and performance of our proposed protocol, the network simulator NS-2 is used for simulation. The simulation results demonstrate that our proposed protocol achieves high data packet delivery ratio and low end-to-end delay compared to traditional routing algorithms such as ACO and ad hoc on-demand distance vector (AODV).

     

多速率Ad hoc网络MAC层公平性的分析与改进

在多速率Ad hoc网络中,利用自适应速率调整算法,网络节点可以根据信道质量选择不同的传输速率,从而提高网络的总体通信能力。对多速率Ad hoc网络MAC层公平性进行了仿真和分析,实验结果表明基于IEEE 802.11的多速率Ad hoc网络中存在严重的公平性问题。通过对吞吐率公平和时间公平的讨论,指出在多速率Ad hoc网络中进行MAC层公平性研究,时间公平性标准是较优的选择。另外提出一种针对多速率Ad hoc网络的改进公平回退（EFB）算法,仿真实验的结果表明该算法能够明显提高多速率Ad hoc网络的MAC层公平性。     

Improving hybrid ad hoc networks: The election of gateways

The selection of an appropriate and stable route that enables suitable load balancing of Internet gateways is an important issue in hybrid mobile ad hoc networks. The variables employed to perform routing must ensure that no harm is caused that might degrade other network performance metrics such as delay and packet loss. Moreover, the effect of such routing must remain affordable, such as low losses or extra signaling messages. This paper proposes a new method, Steady Load Balancing Gateway Election, based on a fuzzy logic system to achieve this objective. The fuzzy system infers a new routing metric named cost that considers several networks performance variables to select the best gateway. To solve the problem of defining the fuzzy sets, they are optimized by a genetic algorithm whose fitness function also employs fuzzy logic and is designed with four network performance metrics. The promising results confirm that ad hoc networks are characterized by great uncertainty, so that the use of Computational Intelligence methods such as fuzzy logic or genetic algorithms is highly recommended.     

无线移动Ad Hoc网络高效路由技术研究

无线移动自组织AdHoc网络是目前国际上前沿和热点的研究领域。综述了AdHoc网络的基本概念、原理、特点、研究现状和相关研究问题,提出了能耗平衡、瞬态链路／路由、路由算法集成等概念和思想,给出了优化路由选择的数学模型,在此基础上提出了我们自己的基于代价优化、能耗平衡、综合考虑链路状况的优化的路由算法,谊算法可以显著提高网络的性能及增加结点和网络的寿命。     

基于贪婪覆盖集的MANET自适应组播路由算法研究

MANET所具有的分布式、多跳、自组织、动态拓扑、时变信道、资源受限等特点,使得传统的有线网和有中心无线网络的路由算法和协议无法在MANET中直接应用,为此需要根据MANET的特点设计专门的组播路由算法和协议.结合基于Mesh和基于树形转发结构两类MANET组播路由的优点,提出一种基于贪婪覆盖集(Greedy Set Cover)的MANET组播路由算法ADMMR(Adaptive Distributed MANET Multicast Route based on Greedy Set Cover),节点可以动态地、分布式计算各自的转发列表,根据转发列表进行组播数据的转发,节省有限的带宽,减少信道冲突,降低网络负载,提高算法的总体性能.最后运用OPNET验证了该算法的有效性.     

Distributed fault tolerant computation of weakly connected dominating set in ad hoc networks

Our purpose in this paper is to propose a self-stabilizing protocol for weakly connected dominating set (WCDS) set in a given ad hoc network graph. WCDS is a particular variant of graph domination predicates which play an important role in routing in ad hoc networks. There are many variants of domination problems in bidirectional networks; WCDS is also useful in forming clusters in ad hoc networks. There are many heuristic and distributed algorithms to compute WCDS in network graphs while almost all of them will need complete information about the network topology and most of them are not fault tolerant or mobility tolerant. Self-stabilization is a protocol design paradigm that is especially useful in resource constrained infrastructure-less networks since nodes can make moves based on local knowledge only and yet a global task is accomplished in a fault tolerant manner; it also facilitates for nodes to enter and exit the network freely. There exist self-stabilizing protocols for minimal spanning tree, total domination, and others. We have shown that the paradigm is capable of designing a protocol for WCDS. Our objective is to mathematically prove the correctness and the convergence of the protocol in any worst-case scenario, as is usually done for self-stabilizing protocols for other graph predicates used for ad hoc networks.     

Adaptive TCP congestion control and routing schemes using cross-layer information for mobile ad hoc networks

Compared with traditional networks, ad hoc networks possess many unique characteristics. For example, ad hoc networks can drop a packet due to network events other than buffer overflow. Unfortunately, the current layered network architecture makes it impossible to pass the information specific to one layer to other layers. As a result, if a packet is lost due to reasons other than buffer overflow, TCP adversely invokes its congestion control procedure. Similarly, the routing algorithm may misinterpret that a path is broken and adversely invoke the route recovery procedure.This study addresses the limitations of the current layered network architecture by adopting a cross-layer protocol design for TCP and routing algorithms in ad hoc networks. The objective of this approach is to enable the lower-layered ad hoc network to detect and differentiate all possible network events, including disconnections, channel errors, buffer overflow, and link-layer contention, that may cause packet loss. Using the information exploited by lower layers, the upper layer-3 routing algorithm, and the layer-4 TCP can take various actions according to the types of network events. Simulation results demonstrate that the combination of the cross-layer optimized TCP and routing algorithms can effectively improve the performance of TCP and DSR, regardless of whether it is in a stationary or a mobile ad hoc network.     

基于改进萤火虫群优化的无线自组网路由算法

针对无线自组网络拓扑结构多变、网络生存时间受限及数据包分组传输效率低下等问题,借鉴萤火虫群优化算法,提出了一种改进萤火虫群优化的无线自组网络路由算法.路由算法将萤火虫优化算法中的荧光素强度更新与无线自组网络中的节点移动速度、拥塞程度、节点剩余能量、节点间距离等因素进行相互映射,同时改进萤火虫群优化算法中的搜索萤火虫、驻留萤火虫及回溯萤火虫用于完成无线自组网络中路由协议的路由发现、路由选择及路由维护等过程,整个协议无须传送大量的控制分组,即可实现无线自组网络的稳定传输.仿真实验结果表明,与AODV及基于蚁群优化的路由算法AntRouting协议相比,本文所提出的路由算法在端到端延时、分组数据传输率及网络生存时间上均有良好的性能.     

一种稳定的按需QoS路由协议

一个ad hoc网络是一个多跳无线网络,网络中的节点互相通信而不依赖于预先架设的固定基础设施，选路协议中的频繁的路由失败和高控制开销致使系统性能降低.本文提出了一个稳定的分布式Ad hoc路由协议，该协议支持QoS选路用于多媒体应用．     

移动自组织网络路由选择算法研究进展

移动Ad Hoc无需基础设施,可支持高动态的移动数据通信,具有广泛应用的前景。然而,其高动态特性导致互联网现有路由协议不再适用。近年来学者针对Ad Hoc网络提出了大量的路由选择算法。给出了各种路由技术分类方法,简述了Ad Hoc网络的基本路由协议和路由选择算法,进而从预测模型、能量模型、位置信息、服务质量控制和安全支持等5个角度,深入分析了当前Ad Hoc网络路由选择算法的最新研究进展。预测模型通过基于历史信息的移动预测,降低了路由选择的时间代价;能耗模型则采用适当的数学模型来描述网络能耗情况,在选路过程中实现了分组传送的能耗最小化和能量负担均衡之间的权衡;基于位置的路由选择算法根据节点的地理位置来标识目的地,从而利用该地理位置信息进行路由选择;服务质量感知的路由选择算法在本地计算中考虑带宽、延迟、能量和电池生命周期,从而在选路过程中提供了服务质量支持;安全路由选择算法则利用适合移动Ad Hoc网络的密钥、哈希链、电子签名等技术对协议交互消息进行加密来保障网络安全。最后从通信开销、计算和存储开销、路径数量、关键节点的存在性以及算法类型等方面详细对比总结了近年来提出的30余种典型路由选择算法,指出了各自的特点...     

TAP: Traffic-aware topology control in on-demand ad hoc networks

Energy efficiency is crucial to achieve satisfactory network lifetime in ad hoc networks. In order to reduce the energy consumption significantly, a node needs to turn off its transceiver. Many existing energy-saving algorithms are based on constructing a simplified routing backbone for global connectivity. In this paper some problems involved with node sleep in on-demand ad hoc networks are addressed firstly. Then we propose a distributed, cross-layer Traffic-Aware Participation (TAP) algorithm, where nodes make decisions on whether to sleep or not based on both the traffic pattern and local connectivity. Nodes get dynamic traffic characteristics as well as active neighbors within two hops via routing control and data packets periodically. We further present a lightweight algorithm to avoid network partition resulted from node sleeping. Simulation results show that, compared to current sleep-based topology control algorithms, TAP achieves better network service quality and lower delay while allowing comparable energy conservation.     

按需式ad hoc移动网络路由协议的研究进展

Ad hoc移动网络是一种完全由移动主机构成的网络，网络拓扑易变，带宽，能源有限是ad hoc移动网络的主要特点，针对这些特点，目前设计的ad hoc路由协议大多采用按需查找方式，该文介绍了这方面研究的最新进展，对几种典型的按需路由协议进行了说明，分析和综合比较，文中分析了目前协议存在的一些问题并提出了相应的改进方法，最后指出了下一步研究方向。     

Minimum disruption service composition and recovery in mobile ad hoc networks

The dynamic nature of mobile ad hoc networks poses fundamental challenges to the design of service composition schemes that can satisfy the end-to-end quality of service requirements and minimize the effect of service disruptions caused by dynamic link and node failures. Although existing research on mobile ad hoc networks has focused on improving reliability, little existing work has considered service deliveries spanning multiple components. Moreover, service composition strategies proposed for wireline networks (such as the Internet) are poorly suited for highly dynamic wireless ad hoc networks.This paper proposes a new service composition and recovery framework designed to achieve minimum service disruptions for mobile ad hoc networks. The framework consists of two tiers: service routing, which selects the service components that support the service path, and network routing, which finds the optimal network path that connects these service components. Our framework is based on the disruption index, which is a novel concept that characterizes different service disruption aspects, such as frequency and duration, that are not captured adequately by conventional metrics, such as reliability and availability.Using the definition of disruption index, we formulate the problem of minimum-disruption service composition and recovery (MDSCR) as a dynamic programming problem and analyze the properties of its optimal solution for ad hoc networks with known mobility plan. Based on the derived analytical insights, we present our MDSCR heuristic algorithm for ad hoc networks with uncertain node mobility. This heuristic algorithm approximates the optimal solution with one-step lookahead prediction, where service link lifetime is predicted based on node location and velocity using linear regression. We use simulations to evaluate the results of our algorithm in various network environments. The results validate that our algorithm can achieve better performance than conventional methods.     

A location routing protocol based on smart antennas for ad hoc networks

Ad hoc networks are a type of mobile networks that function without any fixed infrastructure. One of the weaknesses of ad hoc networks is that route between a source and a destination is likely to break during communication. Location-based routing algorithms are promising in reducing routing overhead in ad hoc networks. Existing location-based routing algorithms employ the Global Positioning System (GPS) as their location information provider, and synchronize information network-wide. Nonetheless, these protocols have some limitations because the use of GPS is not realistic in certain circumstances. Since smart antenna is able to infer direction and ranging information between pairs of ad hoc node, the obtained local position information can be used to improve routing mechanism. This work proposes a novel Location-Enhanced On-Demand (LEOD) routing protocol which is based on smart antenna technique. The LEOD protocol utilizes local position instead of global position to discover routes and make routing decision for the ad hoc network. Theoretical computation and simulation results show that data packet loss rate decreased significantly compared to other methods well-documented in the literature. In addition, this protocol reduces the network control overheads and the power consumption. It also improves network average throughput.     

无线Ad Hoc网络QoS路由协议研究的进展与展望

无线ad hoc网络是一种无固定通信设备支持、节点可自由移动的多跳全分布式无线网络。无线ad hoc网络的应用环境以及与Internet的互连要求它必须提供一定的服务质量(QoS)保证，而QoS路由协议是无线ad hoc网络支持QoS的一个关键理论和技术，也是目前的一个研究热点。本文回顾了近年来国内外在无线ad hoc网络QoS路由协议研究方面取得的研究成果，对已有的无线ad hoc网络的QoS路由协议进行了分类．并对它们作了较全面的概括。总结和深入的比较分析，系统阐述了在无线ad hoc网络中实现QoS路由协议时需要考虑的因素，指出了亟待解决的问题和今后的研究方向。     

移动自组网络中基于启发式环索算法的Anycasting路由的研究

移动无线自组网络（Mobile Ad Hoc Networks）是一种新型的无线网络,网络中不需要固定通信设施的支持,具有很高的灵活性．任播路由（Anycasting Routing）在移动无线自组网络中有着十分重要的潜在应用．该文提出的基于启发式环索算法的Anycasting路由在路由请求过程中能够根据以前搜索中获得的“先验”知识动态地调整搜索的参数,使搜索总是向着“最可能”的方向进行．模拟实验表明,采用启发式环索算法的混合式Anycasting路由在不影响路由正确性的情况下能极大地减少网络中无用的路由请求消息,从而提高网络的整体性能．     

Clustering overhead and convergence time analysis of the mobility-based multi-hop clustering algorithm for mobile ad hoc networks

With the emergence of large mobile ad hoc networks, the ability of existing routing protocols to scale well and function satisfactorily comes into question. Clustering has been proposed as a means to divide large networks into groups of suitably smaller sizes such that prevailing MANET routing protocols can be applied. However, the benefits of clustering come at a cost. Clusters take time to form and the clustering algorithms also introduce additional control messages that contend with data traffic for the wireless bandwidth. In this paper, we aim to analyse a distributed multi-hop clustering algorithm, Mobility-based D-Hop (MobDHop), based on two key clustering performance metrics and compare it with other popular clustering algorithms used in MANETs. We show that the overhead incurred by multi-hop clustering has a similar asymptotic bound as 1-hop clustering while being able to reap the benefits of multi-hop clusters. Simulation results are presented to verify our analysis.     

基于有线的Ad Hoc路由协议的性能评估方法

Ad hoc路由协议可以使用软件仿真、现场试验分析、理论分析等方法对其进行性能分析和评估。由于现场试验分析开销高及实验环境部署复杂等原因,目前,软件仿真是对ad hoc路由协议进行性能评估的主要方法,但这种方法对于一些需要通过实际应用场景对ad hoc网络进行研究的情况并不具有说服力。本文综合各种方法的优缺点,提出一种基于有线网络的ad hoc路由协议性能评估新方法：通过在应用层、网络层、链路层添加各种数据采集探针来采集性能数据。此外,设计并实现了可视化的数据采集分析平台,可以对采集的性能数据进行图形化的展示及分析评估。这种方法不仅弥补了在软件仿真过程中,未考虑操作系统、系统硬件、系统设计、通信环境等敏感因素带来的影响,使得测试结果更逼近真实,而且解决了现场试验分析中性能数据不易获取、开销巨大、场景搭建复杂等问题。最后,通过本文所提出的性能数据采集评估方法对3种典型的ad hoc路由协议进行性能对比分析。     

一种基于跨层功率控制的Ad hoc网络路由算法*

在无线Ad Hoc网络路由协议中引入功率控制不但可以降低网络能量消耗,同时还能改善网络的吞吐量、投递率等性能,已成为当前Ad Hoc网络的一个研究热点.本文提出了一种基于跨层功率控制的按需路由算法CPC-AODV(Cross-layer Power Control Ad hoc On-demand Distance Vector).算法按需建立多个不同功率级的路由,节点选择到目的节点最小功率级的路由来传递分组,并对网络层的数据分组、路由分组和MAC层控制帧的传输采用不同功率控制策略来降低能量消耗.仿真结果表明:算法有利于降低通信能量开销,延长网络寿命,提高网络投递率及改善网络时延.     

Efficient Communication Strategies for Ad Hoc Wireless Networks

An ad hoc wireless network is a collection of wireless mobile hosts forming a temporary network without the aid of any established infrastructure or centralized administration. This type of network is of great importance in situations where it is very difficult to provide the necessary infrastructure, but it is a challenging task to enable fast and reliable communication within such a network. In this paper we model and analyze the performance of so-called power-controlled ad hoc wireless networks: networks where the mobile hosts are able to change their transmission power. We concentrate on finding schemes for routing arbitrary permutations in these networks. In general, it is NP-hard even to find an n ^1-ε -approximation for any constant ε to the fastest possible strategy for routing a given permutation problem on n mobile hosts. However, we demonstrate here that if we allow ourselves to consider slightly less general problems, efficient solutions can be found. We first demonstrate that there is a natural class of distributed schemes for handling node-to-node communication on top of which online route selection and scheduling strategies can be constructed such that the performance of this class of schemes can be exploited in a nearly optimal way for routing permutations in any static power-controlled ad hoc network. We then demonstrate that if we restrict ourselves to the important case of routing between nodes distributed randomly in a Euclidean space, we can route in a time that is asymptotically optimal for any routing scheme. Received in final form January 31, 2000. Online publication October 10, 2000.