431 research outputs found
A Novel Multicasting Scheme over Wireless LAN Systems by Using Relay
Abstract. We propose a novel multicast scheme that can provide qualityof-service (QoS) to multicast service over IEEE 802.11 wireless LANs by utilizing medium access control (MAC) layer relay. It is well known that IEEE 802.11 provides a physical layer multi-rate capability in response to different channel conditions, and hence packets may be delivered at a higher data rate through a relay node than through the direct link if the direct link has low quality and low data rate. We develop the distributed relay node selection algorithm and the relay channel selection algorithm. The effectiveness of proposed scheme is examined by numerical method and simulation. Simulations show that the proposed relayed multicast significantly improves throughput and delay performance
Framework for Content Distribution over Wireless LANs
Wireless LAN (also called as Wi-Fi) is dominantly considered as the most pervasive
technology for Intent access. Due to the low-cost of chipsets and support for high data
rates, Wi-Fi has become a universal solution for ever-increasing application space
which includes, video streaming, content delivery, emergency communication,
vehicular communication and Internet-of-Things (IoT).
Wireless LAN technology is defined by the IEEE 802.11 standard. The 802.11
standard has been amended several times over the last two decades, to incorporate the
requirement of future applications. The 802.11 based Wi-Fi networks are
infrastructure networks in which devices communicate through an access point.
However, in 2010, Wi-Fi Alliance has released a specification to standardize direct
communication in Wi-Fi networks. The technology is called Wi-Fi Direct. Wi-Fi
Direct after 9 years of its release is still used for very basic services (connectivity, file
transfer etc.), despite the potential to support a wide range of applications. The reason
behind the limited inception of Wi-Fi Direct is some inherent shortcomings that limit
its performance in dense networks. These include the issues related to topology
design, such as non-optimal group formation, Group Owner selection problem,
clustering in dense networks and coping with device mobility in dynamic networks. Furthermore, Wi-Fi networks also face challenges to meet the growing number of Wi
Fi users. The next generation of Wi-Fi networks is characterized as ultra-dense
networks where the topology changes frequently which directly affects the network
performance. The dynamic nature of such networks challenges the operators to design
and make optimum planifications.
In this dissertation, we propose solutions to the aforementioned problems. We
contributed to the existing Wi-Fi Direct technology by enhancing the group formation
process. The proposed group formation scheme is backwards-compatible and
incorporates role selection based on the device's capabilities to improve network
performance. Optimum clustering scheme using mixed integer programming is
proposed to design efficient topologies in fixed dense networks, which improves
network throughput and reduces packet loss ratio. A novel architecture using
Unmanned Aeriel Vehicles (UAVs) in Wi-Fi Direct networks is proposed for
dynamic networks. In ultra-dense, highly dynamic topologies, we propose cognitive
networks using machine-learning algorithms to predict the network changes ahead of
time and self-configuring the network
Fly-By-Wireless for Next Generation Aircraft: Challenges and Potential solutions
”Fly-By-Wireless” paradigm based on wireless connectivity in aircraft has the potential to improve efficiency and flexibility, while reducing weight, fuel consumption and maintenance costs. In this paper, first, the opportunities and challenges for wireless technologies in safety-critical avionics context are discussed. Then, the assessment of such technologies versus avionics requirements is provided in order to select the most appropriate one for a wireless aircraft application. As a result, the design of a Wireless Avionics Network based on Ultra WideBand technology is investigated, considering the issues of determinism, reliability and security
An Overview of Mobile Ad Hoc Networks for the Existing Protocols and Applications
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
Vehicular ad hoc networking based on the incorporation of geographical information in the IPv6 header
Several approaches can be identified in the domain of vehicular ad hoc networks (VANET). Internet Protocol version 6 (IPv6) networking and non-IP geographical networking can each fulfill a subset of the application requirements. In general, a combination of both techniques is proposed to meet all of the application requirements. In this case, packets of one VANET routing protocol are encapsulated inside packets of another. This tunneling, together with the position service required for non-IP geographical unicasting, makes such a combined solution rather complex, and hence more challenging to implement, debug, and maintain. In this article, a new VANET approach is presented that relies on the key assumptions that geo-anycast functionality is not required by the applications, and that geographic unicasting is not needed when IP-based unicasting is provided. This enables the adoption of an IPv6-only VANET solution, removing the need for tunneling and position services. New techniques are required to support IPv6-based geo-broadcasting. In this article, it is described how addresses should be assigned, how geographical data can be incorporated in the IPv6 address, how the other IPv6 header fields can be used to contain additional VANET information, and how routing should be handled to guarantee that no modifications are required to the application units. The implementation of the proposed techniques is described, and the correct functionality of the solutions is experimentally demonstrated. Finally, to prove the added value compared to current state-of-the-art propositions, the presented solution is stacked up against the recently released ETSI standards TS 102 636-4-1 (geographical addressing and forwarding) and TS 102 636-6-1 (transmission of IPv6 packets over GeoNetworking protocols)
EVA Radio DRATS 2011 Report
In the Fall of 2011, National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) participated in the Desert Research and Technology Studies (DRATS) field experiments held near Flagstaff, Arizona. The objective of the DRATS outing is to provide analog mission testing of candidate technologies for space exploration, especially those technologies applicable to human exploration of extra- terrestrial rocky bodies. These activities are performed at locations with similarities to extra-terrestrial conditions. This report describes the Extravehicular Activity (EVA) Dual-Band Radio Communication System which was demonstrated during the 2011 outing. The EVA radio system is designed to transport both voice and telemetry data through a mobile ad hoc wireless network and employs a dual-band radio configuration. Some key characteristics of this system include: 1. Dual-band radio configuration. 2. Intelligent switching between two different capability wireless networks. 3. Self-healing network. 4. Simultaneous data and voice communication
Design and implementation of high quality H.264 video streaming over wireless mesh networks
Wireless multimedia home servers are the next generation of home entertainment systems. From a single broadband connection entering a residence, the multimedia stream is transmitted to television headsets and other peripherals by using only wireless links. The provision of high quality time-critical multimedia services in indoor environment is very challenging due to high attenuation and multi-path fading caused by the walls and contention in the shared channel. In this thesis, we demonstrate that the newly proposed wireless standard on wireless mesh networks can help improve the coverage while supporting Quality of Service requirements of both multimedia and data users, when the video packets are given EDCA priorities based on their importance according to the new high definition video streaming standard H.264. We support our hypothesis by presenting test results gathered from both simulations and from a real implementation test bed, where we observe very low delay and very few packet losses in video stream and almost no loss in perceived video quality even in the presence of high contending neighboring data traffi
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
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