197 research outputs found

    Store and Haul: Improving Mobile Ad-Hoc Network Connectivity through Repeated Controlled Flooding

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    This work investigates the benefits and drawbacks of repeating controlled flooding at different intervals in mobile ad hoc networks (MANETs) to overcome episodic connectivity. Specifically, the thesis examines the efficiencies in repeating transmissions by quantifying the packet delivery ratio (PDR) and recording the resulting delays in different types of MANET scenarios. These scenarios mainly focus on partitions within the simulated networks by varying node density and mobility. The nodes store transmitted data and haul it across the MANET in the hope that it will come in range of a node that leads to the destination. A customized version of the Network Simulator 2 (ns-2) is used to create the simulations. A qualitative analysis follows and shows the cost and benefits of increased transmissions at varied time intervals

    Performance Analysis and Design of Mobile Ad-Hoc Networks

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    We focus on the performance analysis and design of a wireless ad-hoc network using a virtual-circuit or reservation based medium access layer. In a reservation based MAC network, source nodes reserve a session's link capacity end-to-end over the entire path before sending traffic over the established path. An example of a generic reservation based MAC protocol is Unifying Slot Assignment Protocol (USAP). Any reservation based medium access protocol (including USAP) uses a simple set of rules to determine the cells or timeslots available at a node to reserve link capacity along the path to the next node. Given inputs of node locations, traffic pattern between nodes and link propagation matrices, we develop models to estimate blocking probability and throughput for reservation based wireless ad-hoc networks. These models are based on extending reduced load loss network models for a wireless network. For generic USAP with multiple frequency channels, the key effect of multiuser interference on a link is modeled via reduced available link capacity where the effects of transmissions and receptions in the link neighborhood are modeled using USAP reservation rules. We compare our results with simulation and obtain good results using our extended reduced load loss network models but with reduced available link capacity distribution obtained by simulation. For the case of generic USAP using a single frequency channel, we develop models for unicast traffic using reduced load loss network models but with the sharing of the wireless medium between a node and its neighbors modeled by considering cliques of neighboring interfering links around a particular link. We compare results of this model with simulation and show good match. We also develop models to calculate source-destination throughput for the reservation MAC as used in the Joint Tactical Radio System to support both unicast and multicast traffic. These models are based on extending reduced load loss network models for wireless multicast traffic with the sharing of the wireless medium between a node and its (upto 2 hop) neighbors modeled by considering cliques of interfering nodes around a particular node. We compare results of this model with simulation and show good match with simulation. Once we have developed models to estimate throughput and blocking probabilities, we use these models to optimize total network throughput. In order to optimize total throughput, we compute throughput sensitivities of the reduced load loss network model using an implied cost formulation and use these sensitivities to choose the routing probabilities among multiple paths so that total network throughput is maximized. In any network scenario, MANETs can get disconnected into clusters. As part of the MANET design problem, we look at the problem of establishing network connectivity and satisfying required traffic capacity between disconnected clusters by placing a minimum number of advantaged high flying Aerial Platforms (APs) as relay nodes at appropriate places. We also extend the connectivity solution in order to make the network single AP survivable. The problem of providing both connectivity and required capacity between disconnected ground clusters (which contain nodes that can communicate directly with each other) is formulated as a summation-form clustering problem of the ground clusters with the APs along with inter-AP distance constraints that make the AP network connected and with complexity costs that take care of ground cluster to AP capacity constraints. The resultant clustering problem is solved using Deterministic Annealing to find (near) globally optimal solutions for the minimum number and locations of the APs to establish connectivity and provide required traffic capacity between disconnected clusters. The basic connectivity constraints are extended to include conditions that make the resultant network survivable to a single AP failure. In order to make the network single AP survivable, we extend the basic connectivity solution by adding another summation form constraint so that the AP network forms a biconnected network and also by making sure that each ground cluster is connected to atleast two APs. We establish the validity of our algorithms by comparing them with optimal exhaustive search algorithms and show that our algorithms are near-optimal for the problem of establishing connectivity between disconnected clusters

    An Overview of Mobile Ad Hoc Networks for the Existing Protocols and Applications

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    Mobile Ad Hoc Network (MANET) is a collection of two or more devices or nodes or terminals with wireless communications and networking capability that communicate with each other without the aid of any centralized administrator also the wireless nodes that can dynamically form a network to exchange information without using any existing fixed network infrastructure. And it's an autonomous system in which mobile hosts connected by wireless links are free to be dynamically and some time act as routers at the same time, and we discuss in this paper the distinct characteristics of traditional wired networks, including network configuration may change at any time, there is no direction or limit the movement and so on, and thus needed a new optional path Agreement (Routing Protocol) to identify nodes for these actions communicate with each other path, An ideal choice way the agreement should not only be able to find the right path, and the Ad Hoc Network must be able to adapt to changing network of this type at any time. and we talk in details in this paper all the information of Mobile Ad Hoc Network which include the History of ad hoc, wireless ad hoc, wireless mobile approaches and types of mobile ad Hoc networks, and then we present more than 13 types of the routing Ad Hoc Networks protocols have been proposed. In this paper, the more representative of routing protocols, analysis of individual characteristics and advantages and disadvantages to collate and compare, and present the all applications or the Possible Service of Ad Hoc Networks.Comment: 24 Pages, JGraph-Hoc Journa

    A Framework to Quantify Network Resilience and Survivability

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    The significance of resilient communication networks in the modern society is well established. Resilience and survivability mechanisms in current networks are limited and domain specific. Subsequently, the evaluation methods are either qualitative assessments or context-specific metrics. There is a need for rigorous quantitative evaluation of network resilience. We propose a service oriented framework to characterize resilience of networks to a number of faults and challenges at any abstraction level. This dissertation presents methods to quantify the operational state and the expected service of the network using functional metrics. We formalize resilience as transitions of the network state in a two-dimensional state space quantifying network characteristics, from which network service performance parameters can be derived. One dimension represents the network as normally operating, partially degraded, or severely degraded. The other dimension represents network service as acceptable, impaired, or unacceptable. Our goal is to initially understand how to characterize network resilience, and ultimately how to guide network design and engineering toward increased resilience. We apply the proposed framework to evaluate the resilience of the various topologies and routing protocols. Furthermore, we present several mechanisms to improve the resilience of the networks to various challenges

    Special Issue on Survivable and Resilient Communication Networks and Services

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    Communication networks and services play a vital role in our modern lives. This importance is expected to continue to grow in future decades. More and more business, healthcare or government organizations will become increasingly dependent on the communication between their offices and people. Not only does modern society depend on these services in terms of availability but also in terms of proper functioning in all circumstances. These services having stringent requirements with respect to protection of privacy and security. Anonymity (such as e-health) cannot accept, for example, temporary leakage of confidential information by accident whether a result of human error or technical problems. The information and communication network technology itself have also been evolving with tremendous breakthroughs. Users have more and more different types of mobile devices that interconnect them to the Internet. These mobile devices provide incentives to generate novel technology paradigms that enable more flexible provisioning, network virtualization, or improved power efficiency. The robustness and fault tolerance of these novel evolutions is as crucial as ever

    Acknowledgement based Intrusion-Detection System for MANETS

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    In the next generation of wireless communication systems, there will be a need for the quick deployment of independent mobile users. notable examples include establishing survivable, efficient, flush communication for emergency/ recover operations, defeat relief efforts, and Army networks. Such network scenarios cannot count on centralized and organized connectivity, and can be make up as applications of  Mobile Ad Hoc Networks.  The primary challenge in building a MANET is equipping each device to continuously maintain the information required to properly route traffic. An intrusion detection system (IDS) is a device or software application that monitors network or system activities for malicious activities or policy violations and produces reports to a management station. IDS come in a variety of “flavors” and approach the goal of detecting suspicious traffic in different ways. The self configuring ability of nodes in MANET made it popular among critical mission applications like army use or emergency recovery. However, the open medium and wide distribution of nodes make MANET vulnerable to malicious attackers. In this case, it is decisive to develop efficient intrusion-detection mechanisms to protect MANET from attacks. By using technology support  we are cut in hardware costs, we are witnessing a current trend of expanding MANETs into industrial applications. To adjust to such trend, we strongly believe that it is vital to address its potential security problem. In this paper, we propose and implement a new intrusion-detection system named Enhanced Adaptive Acknowledgment (EAACK) specially made for MANETs. Compared to contemporary approaches, Enhanced Adaptive ACK demonstrates higher malicious-behavior-detection rates in certain circumstances while does not greatly affect the network performance

    An Innovative Technique to Avoid Traffic Jamming for VANET Using NS-2

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    A range of efficient control of vehicles has grown together with information and communication tools In scrupulous, with the appliance of wireless network for real world information offering, it has been feasible to create Vehicular Ad-hoc Network (VANET), an intellectual vehicle service for ease and protection, which does feasible crash accident detection and prevention, caution of hazardous aspects on road, traffic information offering, and other types of service offering. Nevertheless, the VANET service situation has physical and technical vulnerabilities sourced by the vehicular inside/outside communication based on wireless network. Thus, Vehicular protection has become known as a crucial aspect to avert malevolent threats and confidentiality defiance from vehicles, drivers, and traffic network. In this paper we proposed a scheme for discovering the routing mischief of an attacker aligned with traffic jamming. Now if the congestions take place in a particular section then in that case all vehicular nodes would produce the traffic jam indications known as Jamming declaration indications to their fellow vehicles and through that the vehicular node would modify their direction. Performances of outcomes are calculated on the basis of parameters: Packet Delivery Ratio, Routing Load and Throughput using Network Simulator (NS-2). Keywords: VANET (Vehicular Ad-hoc Network), Vehicle security, traffic jamming, Road Side Uni
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