Home About us Contact
|
Home About us Contact | ||
|
|
||
Data Transmission (data + transmission)
Selected AbstractsData transmission over analog TV broadcastingINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 4 2008Christos S. Koukourlis Abstract The implementation of a contemporary method that enables the transmission of digital information at a rate of 2,Mbps over TV signal using the existing broadcasting infrastructure is described. Detailed information on the prototype hardware is given along with experimental results that prove the validity of the proposed method. Finally, a concept for including the method to the existing TV broadcasting network is proposed. Copyright © 2007 John Wiley & Sons, Ltd. [source] Mobile Agent Computing Paradigm for Building a Flexible Structural Health Monitoring Sensor NetworkCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 7 2010Bo Chen While sensor network approach is a feasible solution for structural health monitoring, the design of wireless sensor networks presents a number of challenges, such as adaptability and the limited communication bandwidth. To address these challenges, we explore the mobile agent approach to enhance the flexibility and reduce raw data transmission in wireless structural health monitoring sensor networks. An integrated wireless sensor network consisting of a mobile agent-based network middleware and distributed high computational power sensor nodes is developed. These embedded computer-based high computational power sensor nodes include Linux operating system, integrate with open source numerical libraries, and connect to multimodality sensors to support both active and passive sensing. The mobile agent middleware is built on a mobile agent system called Mobile-C. The mobile agent middleware allows a sensor network moving computational programs to the data source. With mobile agent middleware, a sensor network is able to adopt newly developed diagnosis algorithms and make adjustment in response to operational or task changes. The presented mobile agent approach has been validated for structural damage diagnosis using a scaled steel bridge. [source] Middleware for real-time distributed simulationsCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 15 2004Thom McLean Abstract Distributed simulation applications often rely on middleware to provide services to support their execution over distributed computing environments. Such middleware spans many levels, ranging from low-level support for data transmission through object request brokers to higher level, simulation specific functionality such as time management. We discuss design alternatives for realizing such middleware for hard real-time distributed simulations such as hardware-in-the-loop applications. We present the results from tests of a prototype implementation of real-time Run-Time Infrastructure middleware. Its performance is compared with a non-real-time implementation. The context for this work is the High Level Architecture standard that has been defined by the U.S. Department of Defense. Copyright © 2004 John Wiley & Sons, Ltd. [source] Novel DLC model for QoS enhancement of bursty VBR traffic in wireless ATM networksEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 8 2008Hosam El-Ocla Several data-link control (DLC) protocol procedures have been proposed in order to provide reliable data transmission over powerless radio links. However, many quality of service (QoS) issues still need to be achieved such as balance between cell transfer delay (CTD) and cell loss rate (CLR), absence of cell delay variation (CDV) and network traffic utilisation. The main problem with wireless ATM is how to overcome the unreliability of the wireless link in order to maintain QoS requirements especially for variable bit rate (VBR) application. Here, we propose a model that provides QoS support for ATM virtual connections (VC) and solves the unreliability problem of the wireless ATM through an efficient DLC protocol for bursty VBR traffic. This model mainly concerns with enhancing QoS to gain error-free wireless transmission and regulating VBR Traffic. Copyright © 2008 John Wiley & Sons, Ltd. [source] Blind equalization of space-time-turbo trellis coded/continuous phase modulation over Rician fading channelsEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 5 2004Osman N. Ucan In this paper, to improve bit error performance and bandwidth efficiency, we combine space-time block codes (STBC), turbo trellis codes and continuous phase modulation and denote space-time-turbo trellis coded/continuous phase modulation (ST-TTC/CPM). For high data transmission over wireless fading channels, STBC provide the maximal possible diversity advantage for multiple decoding algorithms. We present continuous phase modulation (CPM) for ST-TTC signals, since CPM provides low-spectral occupancy and is suitable for power and bandwidth-limited channels. In our model, to utilize STBC efficiently, we need to estimate the channel parameters, which influence the signals having continuity property. Therefore, we develop a blind maximum likelihood channel estimation algorithm for signals propagating through a Rician fading channel. Here, Baum-Welch (BW) algorithm, based on hidden Markov model (HMM), is modified to provide computationally efficient channel parameter estimation. We also investigate the performance of ST-TTC/CPM in the case of no channel state information (CSI) for various Rician parameters K and Doppler frequency. Copyright © 2004 AEI. [source] Graphical models for coded data transmission over inter-symbol interference channelsEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 4 2004Michael Tüchler We derive graphical models for coded data transmission over channels introducing inter-symbol interference. These models are factor graph descriptions of the transmitter section of the communication system, which serve at the same time as a framework to define the corresponding receiver. The graph structure governs the complexity and nature (e.g. non-iterative, iterative) of the receiver algorithm. A particular graph yields several algorithms optimizing various cost functions depending on the choice of messages communicated along the edges of the graph. We study these different outcomes of message passing and how the corresponding receiver algorithms are related to existing ones. We also devise strategies to find suitable graphs for communication problems of interest. Copyright © 2004 AEI [source] Signal Dependence of Cross-Phase Modulation in WDM SystemsEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 2 2000Lutz Rapp In intensity modulated direct detection wavelength division multiplexing (WDM) systems, the effect of cross-phase modulation (XPM) combined with groupvelocity dispersion causes signal distortion, which depends on the transmitted signals. The influence of the mutual dependence of these signals on the resulting degradation of the system performance is investigated theoretically and by means of simulations. Considering the propagation of two digital signals, the eye-closure penalty is determined for different bit patterns and consequences for system design are pointed out. An approximation method is described in order to provide a better understanding of the signal dependence of XPM. Finally, a technique reducing the impact of XPM on data transmission in WDM systems is proposed. [source] Wavelength retuning without service interruption in an all-optical survivable networkINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 6 2009Rose Qingyang Hu Abstract This paper proposes a new wavelength retuning (WRT) scheme in an all-optical WDM network. Compared with the existing WRT schemes developed for all-optical networks, which can alleviate the wavelength-continuity constraint but cannot avoid service interruption or data loss, the proposed scheme is able to alleviate the wavelength-continuity constraint and reduce the connection blocking probability with no service interruption to the on-going traffic. This is achieved by allocating two routes, one for active path and one for backup path, to each incoming connection request and conducting WRT only on the backup path. The backup path provides an alternate path in case of a failure, while the active path carries traffic under normal conditions. Thus, WRT on the backup path will not cause any impact on data transmission. An optimal backup path WRT scheme and a heuristic algorithm are developed and the performance evaluation on the proposed schemes is presented. The simulation results show that the proposed optimal scheme reduces the connection blocking probability by 46.8% on average, while the proposed heuristic scheme reduces the blocking probability by 28.3% on average, all compared with the scheme without WRT. Copyright © 2009 John Wiley & Sons, Ltd. [source] Performance of multi level-turbo coding with neural network-based channel estimation over WSSUS MIMO channelsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 3 2009Ersin Gose Abstract This paper presents the performance of the transmit diversity-multi level turbo codes (TD-MLTC) over the multiple-input,multiple-output (MIMO) channels based on the wide sense stationary uncorrelated scattering (WSSUS). The multi level-turbo code (ML-TC) system contains more than one turbo encoder/decoder block in its structure. At the transmitter side, the ML-TC uses the group partitioning technique that partitions a signal set into several levels and encodes each level separately by a proper component of the encoder to improve error performance. The binary input sequence is passed through the MLTC encoder and mapped to 4-PSK and then fed into the transmit diversity scheme for high data transmission over wireless fading channels. At the receiver side, distorted multi-path signals are received by multiple receiver antennae. WSSUS MIMO channel parameters are estimated by using an artificial neural network and an iterative combiner. Input sequence of the first level of the MLTC encoder is estimated at the first level of MLTC decoder. Subsequently, the other input sequences are computed by using the estimated input bit streams of the previous levels. 4-PSK two-level turbo codes are simulated for 2Tx,1Rx and 2Tx,2Rx antenna configurations over WSSUS MIMO channels. Here, TD-MLTC and its efficient implementations are discussed and simulation results are given. Copyright © 2008 John Wiley & Sons, Ltd. [source] In-building power lines as high-speed communication channels: channel characterization and a test channel ensembleINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 5 2003Tooraj Esmailian Abstract In-building power lines have often been considered as attractive media for high-speed data transmission, particularly for applications like home networking. In this paper, we develop models for power line channels based both on theoretical considerations and practical measurements. We consider power line channel frequency response and noise models in the 1,30 MHz band and propose a number of power line test channels in which to measure the performance of power line modems. Copyright © 2003 John Wiley & Sons, Ltd. [source] Unfairness of measurement-based admission controls in a heterogeneous environmentINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 9 2001Yuan-Cheng Lai Abstract Admission controls are required to determine whether new connections should be admitted to networks. These controls ensure the quality of service (QoS) for data transmission. This paper introduces three measurement-based admission control algorithms called Measured Sum, Hoeffding Bound, and Adaptive Weight Factor. The unfairness of these algorithms in a heterogeneous environment is investigated. Simulation results indicate that the fairness of the Measured Sum exceeds that of the other methods. Admission of connections with large peak rates or travelling many hops can be difficult. Copyright © 2001 John Wiley & Sons, Ltd. [source] Full-duplex analogue/digital data transmission using lasers coupled to GI fibre and its applicationINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 5 2001Masayoshi Kamiya Abstract This paper describes a low-cost version of a full-duplex optical fibre analogue/digital data transmission link whose practical implementation is simplified by using a pair of laser diodes, each having a built-in photodiode for monitoring the laser output power, and its application to vibration test data transmission. The transmission link sends digital data of up to 9600 bps in one direction, and analogue data of DC to 100 kHz and image data specified by an NTSC colour video signal in the opposite direction, all at the same time through one GI optical fibre. Being simple in configuration and stable against noise, this type of link has a variety of applications within factory, home and offices. Copyright © 2001 John Wiley & Sons, Ltd. [source] Design and implementation of WAP-based LAN segment management system using RMON MIBINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 3 2003Jong-Keun Kim Advances in LAN technology have enabled fast data transmission. However, without effective management of these resources, congestion of networks as well as waste of resources are inevitable. Therefore, it is necessary to supervise, report, and even control, if necessary, the network resource status so that the communication network can be effectively operated without service interruption by monitoring traffic among the hosts. Web-based network management systems have been developed and applied for remote management without using specific applications. However, such web-based network management systems have limited manager mobility and poor performance. To overcome such disadvantages, this paper proposes a network management system using wireless communication. Copyright © 2003 John Wiley & Sons, Ltd. [source] Decentralized nonlinear robust control of UAVs in close formationINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 11 2003Sahjendra N. Singh Abstract This paper treats the design of a decentralized nonlinear robust control system for formation flying of multiple unmanned aerial vehicles (UAVs). In close formation, it is assumed that vortex of any UAV affects the motion of all the UAVs behind it. The forces produced by these vortices are complex functions of relative position co-ordinates of the UAVs. In this paper, these forces are treated as unknown functions, which cannot be parameterized. Since the system is not invertible in the wind axes system, a simplified co-ordinate system obtained from the wind axes system for which the velocity roll (bank angle) is zero, is considered for the design of the control system. A nonlinear robust control system for the separation trajectory control of the wing aircraft in the simplified wind coordinate system is derived. Uncertain functions and unmeasured variables are estimated using a high-gain observer for the synthesis of the control system. Each wing UAV synthesizes its control law using its own state variables and the relative position of the preceding UAV with respect to the wing UAV. Thus the control system is decentralized since each UAV has to communicate (depending on sensors for position measurement) with at most one (preceding) UAV, and no data transmission from the remaining vehicles is required. Simulation results for two UAVs are presented which show precise separation trajectory control of each wing UAV in spite of the presence of unknown and unstructured vortex forces, while the lead aircraft maneuvers. Furthermore, these results confirm that when the wing aircraft is positioned properly in the vortex of the lead aircraft, it experiences reduction in its required flight power. Copyright © 2003 John Wiley & Sons, Ltd. [source] Comparison of satellite and cellular architectures for downlink broadcast data transmissionINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 1 2007Adarsh Sridhar Abstract Traditional voice and video-oriented networks such as the cellular and satellite networks are being increasingly used to carry data traffic. We endeavour to compare the downlink broadcast performance of the two architectures against each other on the basis of energy consumption, end-to-end delay and maximum stable throughput. The architectures are modelled as systems of Geo/G/1 queues. Queuing theory arguments and then sample-path based comparisons are used to show that the satellite architecture while being more energy-efficient has a higher delay and a lower maximum throughput. The variation of energy and delay with the total number of receiver nodes is also studied. Copyright © 2006 John Wiley & Sons, Ltd. [source] Theatre in the Sky: a ubiquitous broadband multimedia-on-demand service over a novel constellation composed of quasi-geostationary satellitesINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 3 2006Tarik Taleb Abstract To meet an ever-growing demand for wideband multimedia services and electronic connectivity across the world, development of ubiquitous broadband multimedia systems is gaining a tremendous interest at both commercial and academic levels. Satellite networks will play an indispensable role in the deployment of such systems. A significant number of satellite communication constellations have been thus proposed using Geostationary (GEO), Medium Earth Orbit (MEO), or Low Earth Orbit (LEO) satellites. These constellations, however, either require a potential number of satellites or are unable to provide data transmission with high elevation angles. This paper proposes a new satellite constellation composed of Quasi-GeoStationary Orbit (Quasi-GSO) satellites. The main advantage of the constellation is in its ability to provide global coverage with a significantly small number of satellites while, at the same time, maintaining high elevation angles. Based on a combination of this Quasi-GSO satellites constellation and terrestrial networks, the paper proposes also an architecture for building a global, large-scale, and efficient Video-on-Demand (VoD) system. The entire architecture is referred to as a ,Theatre in the Sky'. Copyright © 2006 John Wiley & Sons, Ltd. [source] Radio resource management across multiple protocol layers in satellite networks: a tutorial overviewINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 5 2005Paolo Barsocchi Abstract Satellite transmissions have an important role in telephone communications, television broadcasting, computer communications, maritime navigation, and military command and control. Moreover, in many situations they may be the only possible communication set-up. Trends in telecommunications indicate that four major growth market/service areas are messaging and navigation services (wireless and satellite), mobility services (wireless and satellite), video delivery services (cable and satellite), and interactive multimedia services (fibre/cable, satellite). When using geostationary satellites (GEO), the long propagation delay may have great impact, given the end-to-end delay user's requirements of relevant applications; moreover, atmospheric conditions may seriously affect data transmission. Since satellite bandwidth is a relatively scarce resource compared to the terrestrial one (e.g. in optical transport networks), and the environment is harsher, resource management of the radio segment plays an important role in the system's efficiency and economy. The radio resource management (RMM) entity is responsible for the utilization of the air interface resources, and covers power control, handover, admission control, congestion control, bandwidth allocation, and packet scheduling. RRM functions are crucial for the best possible utilization of the capacity. RRM functions can be implemented in different ways, thus having an impact on the overall system efficiency. This tutorial aims to provide an overview of satellite transmission aspects at various OSI layers, with emphasis on the MAC layer; some cross-layer solutions for bandwidth allocation are also indicated. Far from being an exhaustive survey (mainly due to the extensive nature of the subject), it offers the readers an extensive bibliography, which could be used for further research on specific aspects. Copyright © 2005 John Wiley & Sons, Ltd. [source] Status and dreams of photonics polymer for ITMACROMOLECULAR SYMPOSIA, Issue 1 2003Yasuhiro Koike Abstract We have proposed a low-loss, high-bandwidth and large-core graded-index plastic optical fiber (GI POF) in data-corn, area. The GI POF enables us to eliminate the "modal noise" problem which is observed in medium-core silica fibers. Therefore, stable high-speed data transmission can be realized by the GI POF rather than medium-core silica fibers. Furthermore, advent of perfluorinated (PF) polymer based GI POF network can support higher transmission than silica fibers network because of the small material dispersion of PF polymer compared with silica. In addition, we proposed a "highly scattering optical transmission (HSOT) polymer" and applied it to a light guide plate of a liquid crystal display backlight. The HSOT polymer backlight that was designed using the HSOT designing simulator demonstrated twice the brightness of the conventional taransparent backlight with sufficient color uniformity. Furthermore, we proposed the two types of zero-birefringence polymers synthesized by the random copolymerization method and the anisotropic molecule dopant method. Both of the polymers exhibited no orientational birefringence for any orientation of polymer chains. [source] The Master Ordnance Repair ProgramNAVAL ENGINEERS JOURNAL, Issue 1 2006William A. Stimson Ph.D. As in most complex endeavors, naval warfighting becomes a series of incremental developments interspersed with breakthrough differences in kind. The shift from sail to steam is a case in point. The shift from battleship to aircraft carrier is another. Today, we are into a third transition-from local command and control to network-centric warfare (Cebrowski 1998). The United States Navy requires-has always required-industrial support. This support falls into two categories: the manufacturers that design and develop new technologies and those who maintain and repair these technologies. Because of proprietorship, the latter have great difficulty keeping current and hence, capable. Yet, the Navy retains them for a host of economic and political reasons. The problem is how best to help these ship repairers renew their skills. As this problem will not go away, perhaps it is time to review how the Navy handled the private sector in the last major transition: from analog to digital data transmission. The answer can be found in the Master Ordnance Repair Program. [source] Reliable and efficient multicast protocol for mobile IP networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 7 2008Sang-Jo Yoo Abstract To provide a multicasting service, several multicast protocols for mobile hosts (MHs) have been proposed. However, all of these protocols have faults, such as non-optimal delivery routes and data loss when hosts move to another network, resulting in insecure multicast data transmissions. Thus, this paper presents a new reliable and efficient multicast routing protocol for mobile IP networks. The proposed protocol provides a reliable multicast transmission by compensating the data loss from the previous mobile agent when a MH moves to another network. In addition, an additional function allows for direct connection to the multicast tree according to the status of agents, thereby providing a more efficient and optimal multicast path. The performance of the proposed protocol is confirmed based on simulations under various conditions. Copyright © 2008 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||||||||