IMMIGRANTS-ENHANCED MULTI-POPULATION GENETIC ALGORITHMS FOR DYNAMIC SHORTEST PATH ROUTING PROBLEMS IN MOBILE AD HOC NETWORKS

One of the most important characteristics in mobile wireless networks is the topology dynamics, that is, the network topology changes over time as a result of energy conservation or node mobility. Therefore, the shortest path (SP) routing problem turns out to be a dynamic optimization problem in mobile wireless networks. In this article, we propose to use multi-population genetic algorithms (GAs) with an immigrants scheme to solve the dynamic SP routing problem in mobile ad hoc networks, which are the representative of new generation wireless networks. Two types of multi-population GAs are investigated. One is the forking GA in which a parent population continuously searches for a new optimum and a number of child populations try to exploit previously detected promising areas. The other is the shifting-balance GA in which a core population is used to exploit the best solution found and a number of colony populations are responsible for exploring different areas in the solution space. Both multi-population GAs are enhanced by an immigrants scheme to handle the dynamic environments. In the construction of the dynamic network environments, two models are proposed and investigated. One is called the general dynamics model, in which the topologies are changed because the nodes are scheduled to sleep or wake up. The other is called the worst dynamics model, in which the topologies are altered because some links on the current best shortest path are removed. Extensive experiments are conducted based on these two models. The experimental results show that the proposed multi-population GAs with immigrants enhancement can quickly adapt to the environmental changes (i.e., the network topology changes) and produce high-quality solutions after each change.     

Performance evaluation of a mesh-evolving quality-of-service-aware multicast routing protocol for mobile ad hoc networks

The tremendous amount of multimedia applications running across the wireless communication medium makes quality of service (QoS) a fundamental requirement for mobile ad hoc networks. However, it is not easy to incorporate QoS into these networks. Moreover, the growing number of group-oriented applications also necessitates the efficient utilisation of network resources. The multicast model is a promising technique which can achieve this efficiency by facilitating the inherent broadcast capability of the wireless medium. The mesh-evolving ad hoc QoS multicast (MAQM) routing protocol is developed to address the resource efficiency and QoS problems with one, integrated solution. MAQM achieves multicast efficiency by tracking the availability of resources for each node within its neighbourhood. The QoS status is monitored continuously and announced periodically to the extent of QoS provision. Using these features, MAQM nodes can make their decisions on joining a new multicast session based on the sustainability of their perceived QoS. MAQM also evolves the initial multicast tree into a mesh during the course of an ongoing session to achieve a more robust network topology. Thus, MAQM integrates the concept of QoS-awareness into multicast routing in mobile ad hoc networks. Since ad hoc networks require the protocol control overhead to be as small as possible, we analyse the multicast session establishment process of MAQM to see its impact on the protocol performance in terms of system control overhead. We also evaluate the performance of MAQM through computer simulations using various qualitative and quantitative criteria. The simulation results validate our mathematical analysis of the control overhead and show that MAQM significantly improves multicast efficiency through its QoS-aware admission and routing decisions with an acceptably small overhead. Thus, MAQM shows that QoS is not only essential for, but also applicable to mobile ad hoc networks.     

QoS routing with traffic distribution in mobile ad hoc networks

Mobile ad hoc networks (MANETs) follow a unique organizational and behavioral logic. MANETs’ characteristics such as their dynamic topology coupled with the characteristics of the wireless communication medium make Quality of Service provisioning a difficult challenge. This paper presents a new approach based on a mobile routing backbone for supporting Quality of Service (QoS) in MANETs. In real-life MANETs, nodes will possess different communication capabilities and processing characteristics. Hence, we aim to identify those nodes whose capabilities and characteristics will enable them to take part in the mobile routing backbone and efficiently participate in the routing process. Moreover, the route discovery mechanism we developed for the mobile routing backbone dynamically distributes traffic within the network according to current network traffic levels and nodes’ processing loads. Simulation results show that our solution improves network throughput and packet delivery ratio by directing traffic through lowly congested regions of the network that are rich in resources. Moreover, our protocol incurs lower communication overheads than AODV (ad hoc on-demand distance vector routing protocol) when searching for routes in the network.     

移动Ad Hoc网络中一种多播路由协议算法实现

MANET是一个多跳,节点无中心、自组织、互相通信而不依赖于预先架设的固定基础设施无线移动网络。本文提出了采用按需路由发现策略的移动Ad Hoc多播路由算法。此算法不需要维护全局的路由信息,通过按需路由发现过程,动态更新路由信息和建立多播转发组。多播数据包在转发组成员间进行有限泛洪,能够降低带宽的占用及减少路由更新信息的传播。仿真实验显示多播算法在带宽较低、多播组成员数量变化较大的移动分组无线网环境中,具有较好的可靠性和工作效率。     

Ad hoc无线网络中的组播路由协议

由固定网络、基础结构移动网络和非基础结构无线网络组成的集成网络将成为未来互联网发展的趋势。同时,面向组计算和组通信的需求不断增长,要求未来的集成网络能为用户提供组播通信的功能。Adhoc无线网络是非基础结构无线网络的典型代表,具有带宽有限、拓扑结构易变和电池能源有限的特点,这些特性使得未来集成网络实现组播通信具有一定的挑战性。该文在分析Adhoc无线网络基本特性的基础上,综合评述了新近的Adhoc网络组播路由协议的研究现状,并对几种典型的Adhoc网络组播路由协议的特点进行了分类分析和比较,最后讨论了Adhoc无线网络组播路由协议的发展趋势和挑战。     

Localized Operations for Distributed Minimum Energy Multicast Algorithm in Mobile Ad Hoc Networks

To explore the advantages of power saving offered by the wireless multicast advantage property, we consider the case of source-initiated multicast traffic. Current research activity for the minimum energy multicast (MEM) problem has been focused on devising efficient centralized greedy algorithms for static ad hoc networks. In this paper, we consider mobile ad hoc networks (MANETs) that use omnidirectional antennas and have limited energy resources. We propose the design and initial evaluation of the distributed minimum energy multicast (DMEM) algorithm for MANETs that attempts to reduce as much as possible the total RF energy required by the multicast communication. Several localized operations are presented for the DMEM algorithm, in which each node requires only the knowledge of and distances to all neighboring tree nodes. Through extensive simulation studies, we show that these operations are very efficient both in terms of energy saving and operation overhead     

基于Ad Hoc的QoS多播路由协议研究

近年来,随着计算机网络和无线通信技术的迅速发展,无线移动AdHoc网络在军事和民用方面获得了大量应用。多媒体业务的引入对AdHoc网络提出了多播和QoS服务的需求,如何在AdHoc网络中实现有效的多播和QoS服务是一项十分困难和具有挑战性的工作。论文介绍了当前几种比较典型的QoS多播路由协议,并且从多个方面对它们的特性进行了比较分析,最后对AdHoc网络的QoS多播路由协议的进一步研究提出了预测和展望。     

A scalable multimedia QoS architecture for ad hoc networks

Communication demands have grown from separate data and voice to integrated multimedia, paving the way to converging fixed, mobile and IP networks. Supporting Multimedia is a challenging task for wireless ad hoc network designers. Multimedia forms high data rate traffic with stringent Quality of Service (QoS) requirements. Wireless ad hoc networks are characterized by frequent topology changes, unreliable wireless channel, network congestion and resource contention. Providing scalable QoS is the most important challenge for multimedia delivery over ad hoc networks. We introduce here a provisioning and routing architecture for ad hoc networks which scales well while provisioning QoS. The proposed architecture is analysed using a mix of HTTP, voice and video streaming applications over 54 Mbps 802.11 g-based ad hoc networks. The architecture is simulated and compared to well-known routing protocols using the OPNET Modeller. The results show that our architecture scales well with increase in the network size, and outperforms well-known routing protocols.     

Standardisation advancements in the area of routing for mobile ad-hoc networks

Mobile Ad hoc Networks (MANETs) are self-organized and fully distributed networks that rely on the collaboration of participating devices to route data from source to destination. The MANET paradigm is expected to enable ubiquitous mobile communication and thus the proliferation of pervasive applications. The MANET Working Group (WG) of the Internet Engineering Task Force (IETF) is responsible for standardizing an appropriate Internet Protocol (IP) based routing protocol functionality for both static (mesh) and dynamic (mobile) wireless ad hoc network topologies. In this paper, we provide a background on the possibility to use MANETs for enabling future pervasive internet and innovative ubiquitous services. We also describe the work achieved by the MANET WG thus far on the area of secure unicast and multicast routing for MANETs. We also examine non-IETF work on this area, chiefly based on adaptive and hybrid routing. The paper then presents comparative performance evaluations of discussed routing protocols. It is mainly observed that there is a need for adaptive hybrid routing approaches in order to support future innovative and pervasive applications. Consequently, we present our conclusions.     

End-to-end support for statistical quality of service in heterogeneous mobile ad hoc networks

In heterogeneous mobile ad hoc networks (MANETs), different types of mobile devices with diverse capabilities may coexist in the same network. The heterogeneity of MANETs makes end-to-end support for quality of service (QoS) guarantees more difficult than in other types of networks, not to mention the limited bandwidth and frequent topology changes of these networks. Since QoS routing is the first step toward achieving end-to-end QoS guarantees in heterogeneous MANETs, we propose a QoS routing protocol for heterogeneous MANETs. The proposed protocol, called virtual grid architecture protocol (VGAP), uses a cross-layer approach in order to provide end-to-end statistical QoS guarantees. VGAP operates on a fixed virtual rectilinear architecture (virtual grid), which is obtained using location information obtained from global positioning system (GPS). The virtual grid consists of a few, but possibly more powerful, mobile nodes known as ClusterHeads (CHs) that are elected periodically. CHs discover multiple QoS routes on the virtual grid using an extended version of the open shortest path first (OSPF) routing protocol and an extended version of WFQ scheduling policy that takes into account the wireless channel state. Moreover, VGAP utilizes a simple power control algorithm at the physical layer that provides efficient energy savings in this heterogeneous setting. Simulation experiments show that VGAP has a good performance in terms of packet delivery ratio, end-to-end packet delay, call blocking probability, and network scalability.     

高动态飞行器自组织网络组网研究

节点高速移动和网络拓扑变化迅速严重影响着高动态飞行器自组织网络性能。提出了一种适于高动态场景的移动自组织网络协议栈设计。该设计着重QoS需求,围绕网络拓扑高动态变化特征,合理配置不同层次的网络协议,适合高动态应用场景。以平面网络为例,分析评估了FANET网络在高动态环境下的性能。实验结果表明,该组网方式可行并能满足高动态飞行器自组织网络的功能和性能需求。还提出了节点在个体移动方式下保持网络高性能的最佳节点数目和网络各层次协议适应高动态拓扑变化的应对策略。     

Ad Hoc网络多路径需求路由及路径熵选择算法

无线移动Ad Hoc网络是一种不依赖任何固定基础设施的移动无线多跳网络.由于其动态性和资源的限制,在Ad Hoc网络中提供多路径路由是一个重要的研究课题.描述了一种Ad Hoc网络中基于信息熵选择的稳定多路径路由算法(stability multipath on-demand routing,简称SMDR),提出了路径熵的度量参数,并利用路径熵来选择稳定的、长寿命的多路径,减少了重构路由的次数,从而在网络拓扑频繁变化的Ad Hoc网络环境中较好地提供QoS保证和提高数据传输率.仿真结果表明,SMDR协议改进了分组传输率、端到端时延和路由负载率.SMDR协议为解决动态的Ad Hoc网络多路径传输提供了一种新的有效途径.     

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.     

Improving routing distance for geographic multicast with Fermat points in mobile ad hoc networks

In mobile ad hoc networks (MANETs), each node has the ability to transmit, receive, and route packets, and also moves through the field either randomly or in accordance with a pre-planned route. For enhancing the performance of MANETs, reducing the routing distance is a primary concern. For either ad hoc or static networks, the problem of minimizing the overall routing distance during multicasting is NP-complete. Therefore, it is difficult to determine an optimal solution. This paper presents an efficient geographic multicast protocol, designated as GMFP, based on the use of Fermat points. The objective of GMFP is to improve the overall routing distance for multicast tasks. Through a series of simulations, it is shown that GMFP outperforms the conventional Position-Based Multicast protocol and FERMA protocol in terms of the total routing distance, the packet transmission delay, the packet delivery ratio, and the node energy consumption. The performance improvements provided by GMFP are apparent as the scale of the network topology increases.     

MANET中MAODV与ODMRP组播路由协议的研究与分析

MANET是非基础结构无线网络的典型代表,具有带宽有限、拓扑结构易变和电池能源有限的特点,这些特性使得未来集成网络实现组播通信具有一定的挑战性。该文首先介绍了MANET组播路由协议MAODV和ODMRP,然后对两种协议进行了比较分析,并得出结论。     

无线Ad Hoc网络支持QoS的研究进展与展望

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,然而,无线信道固有的特点及节点移动造成网络拓扑的频繁变化,使得在无线ad hoc网络中支持QoS面临许多新的挑战.从无线ad hoc网络的QoS体系结构、QoS路由、QoS信令、支持业务区分和资源预留的介质访问控制协议这4个方面出发,对近年来国内外在该方向取得的研究成果作了全面的概括总结和比较分析,系统阐述了在无线ad hoc网络中支持QoS的问题,指出了亟待解决的问题和今后的研究方向.     

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。     

Using particle swam optimization for QoS in ad-hoc multicast

A mobile ad hoc network (MANET) is a collection of self-organized mobile nodes that are capable of communicating with each other without the aid of any established infrastructure or centralized administration. Multicasting plays a very important role in the application of ad hoc networks. As the number of participants increases, scalability of the multicast protocol becomes an important issue. When considering the increasing demand of Quality-of-Service (QoS) requirements in many applications, the existing multicast routing protocols used for ad-hoc network should be adapted appropriately to effectively meet the stringent QoS requirements of specific multimedia traffic. We thus propose a multicast routing protocol which tries its best to meet the variation of behavior of network topology and satisfy QoS requirements of specific multimedia traffic using particle swam optimization (PSO) in the volatile environments of a MANET. Meanwhile, a priority scheduler with PSO is also proposed to make scheduling decisions so that the packet loss rate can be further reduced. The results of a series of simulations exhibit the practicability and feasibility of our protocol.     

TCP Issues in Mobile Ad Hoc Networks: Challenges and Solutions

Mobile ad hoc networks （MANETs） are a kind of very complex distributed communication systems with wireless mobile nodes that can be freely and dynamically self-organized into arbitrary and temporary network topologies. MANETs inherit several limitations of wireless networks, meanwhile make new challenges arising from the specificity of MANETs, such as route failures, hidden terminals and exposed terminals. When TCP is applied in a MANET environment, a number of tough problems have to be dealt with. In this paper, a comprehensive survey on this dynamic field is given. Specifically, for the first time all factors impairing TCP performance are identified based on network protocol hierarchy, i.e., lossy wireless channel at the physical layer; excessive contention and unfair access at the MAC layer; frail routing protocol at the network layer, the MAC layer and the network layer related mobile node; unfit congestion window size at the transport layer and the transport layer related asymmetric path. How these factors degrade TCP performance is clearly explained. Then, based on how to alleviate the impact of each of these factors listed above, the existing solutions are collected as comprehensively as possible and classified into a number of categories, and their advantages and limitations are discussed. Based on the limitations of these solutions, a set of open problems for designing more robust solutions is suggested.