4,521 research outputs found

    SDDV: scalable data dissemination in vehicular ad hoc networks

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    An important challenge in the domain of vehicular ad hoc networks (VANET) is the scalability of data dissemination. Under dense traffic conditions, the large number of communicating vehicles can easily result in a congested wireless channel. In that situation, delays and packet losses increase to a level where the VANET cannot be applied for road safety applications anymore. This paper introduces scalable data dissemination in vehicular ad hoc networks (SDDV), a holistic solution to this problem. It is composed of several techniques spread across the different layers of the protocol stack. Simulation results are presented that illustrate the severity of the scalability problem when applying common state-of-the-art techniques and parameters. Starting from such a baseline solution, optimization techniques are gradually added to SDDV until the scalability problem is entirely solved. Besides the performance evaluation based on simulations, the paper ends with an evaluation of the final SDDV configuration on real hardware. Experiments including 110 nodes are performed on the iMinds w-iLab.t wireless lab. The results of these experiments confirm the results obtained in the corresponding simulations

    Wireless industrial monitoring and control networks: the journey so far and the road ahead

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    While traditional wired communication technologies have played a crucial role in industrial monitoring and control networks over the past few decades, they are increasingly proving to be inadequate to meet the highly dynamic and stringent demands of today’s industrial applications, primarily due to the very rigid nature of wired infrastructures. Wireless technology, however, through its increased pervasiveness, has the potential to revolutionize the industry, not only by mitigating the problems faced by wired solutions, but also by introducing a completely new class of applications. While present day wireless technologies made some preliminary inroads in the monitoring domain, they still have severe limitations especially when real-time, reliable distributed control operations are concerned. This article provides the reader with an overview of existing wireless technologies commonly used in the monitoring and control industry. It highlights the pros and cons of each technology and assesses the degree to which each technology is able to meet the stringent demands of industrial monitoring and control networks. Additionally, it summarizes mechanisms proposed by academia, especially serving critical applications by addressing the real-time and reliability requirements of industrial process automation. The article also describes certain key research problems from the physical layer communication for sensor networks and the wireless networking perspective that have yet to be addressed to allow the successful use of wireless technologies in industrial monitoring and control networks

    Vehicle to vehicle (V2V) wireless communications

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    This work focuses on the vehicle-to-vehicle (V2V) communication, its current challenges, future perspective and possible improvement.V2V communication is characterized by the dynamic environment, high mobility, nonpredective scenario, propagation effects, and also communicating antenna's positions. This peculiarity of V2V wireless communication makes channel modelling and the vehicular propagation quite challenging. In this work, firstly we studied the present context of V2V communication also known as Vehicular Ad-hoc Netwok (VANET) including ongoing researches and studies particularly related to Dedicated Short Range Communication (DSRC), specifically designed for automotive uses with corresponding set of protocols and standards. Secondly, we focused on communication models and improvement of these models to make them more suitable, reliable and efficient for the V2V environment. As specifies the standard, OFDM is used in V2V communication, Adaptable OFDM transceiver was designed. Some parameters as performance analytics are used to compare the improvement with the actual situation. For the enhancement of physical layer of V2V communication, this work is focused in the study of MIMO channel instead of SISO. In the designed transceiver both SISO and MIMO were implemented and studied successfully

    Performance analysis of time slicing in DVB-H

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    TV is the biggest media and the last one missing from mobile phones. Digital Video Broadcasting for Handhelds (DVB-H) is the latest development from the DVB Project targeting handheld, battery powered devices such as mobile telephones, PDAs(Personal Digital Assistants), etc. Time Division Multiplexing (TDM) is the technology that is usually used in computer and telecommunication systems. Time slicing is one of the characteristics that makes it possible to broadcast high resolution TV programes and fast IP data services to battery powered handheld terminals. This paper discusses the characteristics and advantages of Time slicing algorithm in DVB-H and presents the performance analysis of time slicing in DVB-H through both theoretical analysis and software simulation

    Performance Comparison of Dual Connectivity and Hard Handover for LTE-5G Tight Integration in mmWave Cellular Networks

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    MmWave communications are expected to play a major role in the Fifth generation of mobile networks. They offer a potential multi-gigabit throughput and an ultra-low radio latency, but at the same time suffer from high isotropic pathloss, and a coverage area much smaller than the one of LTE macrocells. In order to address these issues, highly directional beamforming and a very high-density deployment of mmWave base stations were proposed. This Thesis aims to improve the reliability and performance of the 5G network by studying its tight and seamless integration with the current LTE cellular network. In particular, the LTE base stations can provide a coverage layer for 5G mobile terminals, because they operate on microWave frequencies, which are less sensitive to blockage and have a lower pathloss. This document is a copy of the Master's Thesis carried out by Mr. Michele Polese under the supervision of Dr. Marco Mezzavilla and Prof. Michele Zorzi. It will propose an LTE-5G tight integration architecture, based on mobile terminals' dual connectivity to LTE and 5G radio access networks, and will evaluate which are the new network procedures that will be needed to support it. Moreover, this new architecture will be implemented in the ns-3 simulator, and a thorough simulation campaign will be conducted in order to evaluate its performance, with respect to the baseline of handover between LTE and 5G.Comment: Master's Thesis carried out by Mr. Michele Polese under the supervision of Dr. Marco Mezzavilla and Prof. Michele Zorz

    The Design of a CD Transport for Audio Applications

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    The project to design a CD transport (CD player) in conjunction with Perreaux Industries came about from the need for a source component in their Silhouette series of products. This project describes the design a high quality CD player, at a low price, to compliment Perreaux's Silhouette series. A CD drive is selected over a proprietary optical pickup due to the former's low cost and the standardisation of the interface. The control circuitry includes a micro controller and discrete logic to provide the correct data and clock signals to the SPDIF transmitter and DAC circuits. These two circuits provided a high quality analogue output, and facilitate an upgrade path by connecting the SPDIF output to an external DAC. After three board iterations, a final production ready revision was achieved. The design includes a high quality toroidal transformer, low jitter crystal oscillator, and a very high quality SPDIF pulse transformer output. The design also allows a remote input to control the player, and an optional digital cable via an RJ45 connector to provide synchronisation with a future design of the SXD2 DAC module, or to transmit SPDIF to a remote location. The specifications of the final design were higher than expectations. The digital output boasts equal or superior performance to competitive products in the same price range, with the analogue output attaining exceptionally high performance
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