530 research outputs found
A Performance Comparison of Virtual Backbone Formation Algorithms for Wireless Mesh Networks
Currently wireless networks are dominant by star
topology paradigm. Its natural the evolution is towards wireless mesh
multi-hop networks. This article compares the performance of several
algorithms for virtual backbone formation in ad hoc mesh networks
both theoretically and through simulations. Firstly, an overview of the
algorithms is given. Next, the results of the algorithm simulations
made with the program Dominating Set Simulation Suite (DSSS) are
described and interpreted. We have been extended the simulator to
simulate the Mobile Backbone Network Topology Synthesis
Algorithm. The results show that this algorithm has the best
combination of performance characteristics among the compared
algorithms
Evaluation of Short-Range Wireless Technologies for Automated Meter Reading (AMR) Systems
The paper presents the results of the evaluation of some short-range wireless technologies suitable for communications in AMR systems. The typical AMR system structure is described, an overview of three candidate technologies, Wi-Fi, ZigBee and wireless M-Bus, is provided. The evaluation of these technologies is given, based on a selected set of properties, and the results of measurements in two real-world scenarios are summarised
Strategies and challenges for interconnecting wireless mesh and wireless sensor networks
Wireless sensor networks and wireless mesh networks are popular research subjects. The interconnection of both network types enables next-generation applications and creates new optimization opportunities. However, current single-gateway solutions are suboptimal, as they do not allow advanced interactions between sensor networks (WSNs) and mesh networks (WMNs). Therefore, in this article, challenges and opportunities for optimizing the WSN-WMN interconnection are determined. In addition, several alternative existing and new interconnection approaches are presented and compared. Furthermore, the interconnection of WSNs and WMNs is used to study challenges and solutions for future heterogeneous network environments. Finally, it is argued that the use of convergence layers and the development of adaptive network protocols is a promising approach to enable low end devices to participate in heterogeneous network architectures
Security and Privacy Issues in Wireless Mesh Networks: A Survey
This book chapter identifies various security threats in wireless mesh
network (WMN). Keeping in mind the critical requirement of security and user
privacy in WMNs, this chapter provides a comprehensive overview of various
possible attacks on different layers of the communication protocol stack for
WMNs and their corresponding defense mechanisms. First, it identifies the
security vulnerabilities in the physical, link, network, transport, application
layers. Furthermore, various possible attacks on the key management protocols,
user authentication and access control protocols, and user privacy preservation
protocols are presented. After enumerating various possible attacks, the
chapter provides a detailed discussion on various existing security mechanisms
and protocols to defend against and wherever possible prevent the possible
attacks. Comparative analyses are also presented on the security schemes with
regards to the cryptographic schemes used, key management strategies deployed,
use of any trusted third party, computation and communication overhead involved
etc. The chapter then presents a brief discussion on various trust management
approaches for WMNs since trust and reputation-based schemes are increasingly
becoming popular for enforcing security in wireless networks. A number of open
problems in security and privacy issues for WMNs are subsequently discussed
before the chapter is finally concluded.Comment: 62 pages, 12 figures, 6 tables. This chapter is an extension of the
author's previous submission in arXiv submission: arXiv:1102.1226. There are
some text overlaps with the previous submissio
Design, implementation & first run problems of a factory corporate network
En aquest projecte s'ha dut a terme el disseny de la infraestructura de comunicacions i de
xarxa d'una fà brica que comptarà amb zones de producció i d’oficines corporatives, s'han
analitzat les subseqĂĽents necessitats dels recursos de comunicacions dels diferents
departaments per determinar els equipaments de xarxa necessaris, aixĂ com la topologia
de la jerarquia d'interconnexions.
Igualment, s'ha tingut en compte la infraestructura de connexions sense fils per donar
cobertura als dispositius tant corporatius com de dispositius personals o treballadors
externs.
Un cop establerta la topologia de xarxa, s'ha realitzat l'assignaciĂł d'adreces IP,
segmentant la xarxa en diferents VLANs segons una classificaciĂł de funcionalitats i
necessitats de la mateixa (nombre de dispositius, servidor DHCP, nivells de seguretat…)
Finalment, s'ha realitzat un estudi econòmic respecte al pressupost del qual es disponia
per al projecte i el que finalment ha fet falta per cobrir tot el material, obres i hores
d’enginyeria necessaris per a la realització d'aquest.In this project, the design of the communications and network infrastructure of a factory
that will have production areas and corporate offices has been carried out, the subsequent
needs of the communications resources of the different departments have been analyzed
for determine the necessary network equipment, as well as the topology of the
interconnection hierarchy.
Similarly, the infrastructure of wireless connections has been taken into account to provide
coverage for both corporate devices and personal devices or external workers.
Once the network topology has been established, the assignment of IP addresses has
been carried out, segmenting the network into different VLANs according to a
classification of functionalities and its needs (number of devices, DHCP server, security
levels...) Finally , an economic study has been carried out with respect to the budget that
was available for the project and what was ultimately needed to cover all the material,
works and hours of engineering necessary to carry it out
Scanless Fast Handoff Technique Based on Global Path Cache for WLANs
Wireless LANs (WLANs) have been widely adopted and are more convenient as they are inter-connected as wireless campus networks and wireless mesh networks. However, timesensitive multimedia applications, which have become more popular, could suffer from long end-to-end latency in WLANs.This is due mainly to handoff delay, which in turn is caused by channel scanning. This paper proposes a technique called Global Path-Cache (GPC) that provides fast handoffs in WLANs.GPC properly captures the dynamic behavior of the network andMSs, and provides accurate next AP predictions to minimize the handoff latency. Moreover, the handoff frequencies are treated as time-series data, thus GPC calibrates the prediction models based on short term and periodic behaviors of mobile users. Our simulation study shows that GPC virtually eliminates the need to scan for APs during handoffs and results in much better overall handoff delay compared to existing methods
Scanless Fast Handoff Technique Based on Global Path Cache for WLANs
Wireless LANs (WLANs) have been widely adopted and are more convenient as they are inter-connected as wireless campus networks and wireless mesh networks. However, timesensitive multimedia applications, which have become more popular, could suffer from long end-to-end latency in WLANs.This is due mainly to handoff delay, which in turn is caused by channel scanning. This paper proposes a technique called Global Path-Cache (GPC) that provides fast handoffs in WLANs.GPC properly captures the dynamic behavior of the network andMSs, and provides accurate next AP predictions to minimize the handoff latency. Moreover, the handoff frequencies are treated as time-series data, thus GPC calibrates the prediction models based on short term and periodic behaviors of mobile users. Our simulation study shows that GPC virtually eliminates the need to scan for APs during handoffs and results in much better overall handoff delay compared to existing methods
Routing in Large Scale tactical mobile ad hoc Networks
The current Transformation of the military networks adopts the MANET as a main component of the tactical domain. Indeed, a MANET is the right solution to enable highly mobile, highly reactive and quickly deployable tactical networks. Many applications such as the Situational Awareness rely on group communications, underlying the need for a multicast service within the tactical environment where the MANET is employed as a transit network. The purpose of this thesis is to study the setting up of an optimal multicast service within this tactical environment. We firstly focus on defining the protocol architecture to carry out within the tactical network paying particular attention to the MANET. This network is interconnected with different types of networks based on IP technologies and implementing potentially heterogeneous multicast protocols. The tactical MANET is supposed to be made of several hundred of mobile nodes, which implies that the scalability is crucial in the multicast protocol architecture choice. Since the concept of clustering proposes interesting scalability features, we consider that the MANET is a clustered network. Thereby, we define two multicast routing protocols adapted to the MANET: firstly STAMP that is in charge of the multicast communications within each cluster and secondly SAFIR that handles multicast flows between the clusters. These two protocols that can be implemented independently, act in concert to provide an efficient and scalable multicast service for the tactical MANET. Then, we study the interoperability of these multicast protocols employed within the MANET with those employed in the heterogeneous networks that it is interconnected with in order to guarantee end-to-end seamless multicast services to users. Finally, since the multicast protocols proposed in this thesis rely on underlying unicast routing protocols, we propose, in the last chapter, a scalable unicast routing protocol based on OLS
Wireless communication, identification and sensing technologies enabling integrated logistics: a study in the harbor environment
In the last decade, integrated logistics has become an important challenge in
the development of wireless communication, identification and sensing
technology, due to the growing complexity of logistics processes and the
increasing demand for adapting systems to new requirements. The advancement of
wireless technology provides a wide range of options for the maritime container
terminals. Electronic devices employed in container terminals reduce the manual
effort, facilitating timely information flow and enhancing control and quality
of service and decision made. In this paper, we examine the technology that can
be used to support integration in harbor's logistics. In the literature, most
systems have been developed to address specific needs of particular harbors,
but a systematic study is missing. The purpose is to provide an overview to the
reader about which technology of integrated logistics can be implemented and
what remains to be addressed in the future
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