7,419 research outputs found

    Reducing the required transmitted power for personal communication devices in indoor-video spread-spectrum transmission

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    This paper analyzes the use of a coded multicode spread-spectrum technique to reduce radio power for personal communication devices in indoor video transmission. The performance of indoor video transmission is measured by the outage probability, which is the probability that the instantaneous bit error rate (BER) exceeds an acceptable level. We first derive the outage probability. The result is used to characterize the power reduction. It is found that the amount of power reduction depends on the required BER level. For indoor video transmission, which typically requires a BER of 10-5, a substantial power reduction exceeding 3dB can be obtained. If outer coding is used in order that the BER requirement can be relaxed, results show that it is preferred to maintain the required BER to be less than 10-4 for more-effective utilization of the power-reduction capability.published_or_final_versio

    Ultra Wideband Preliminaries

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    Personal area technologies for internetworked services

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    Enhanced Optical Wireless Channel For Indoor And Intravehicle Communications: Power Distribution And Signal To Noise Ratio Analysis

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    Visible light communication—(VLC) provides wide bandwidth and high security capabilities for free space optical communication. This thesis presents the key concepts, underlying principles and practical applications of visible light communications. In particular, this thesis focuses on the received power distribution pattern and signal to noise ratio for line-of-sight indoor and vehicular applications. Several methods are used to modify the SNR and power distribution levels. It is shown that in the absence of obstruction, the optical footprint is nearly circular and offers a platform for large- scale deployment in commercial environments, which is similar to micro and Pico cells. By studying various kinds of commonly used VLC channel analysis: diffuse and line of sight channels, a simple improved indoor and intra-vehicular VLC transmission model for power distribution and SNR is presented. Employing optical wireless communications within the vehicle not only enhances user mobility, but also alleviates radio frequency interference, and lowers system cost through the utilization of license free spectrum. Moreover, a solution to increase the received power by changing the semi angle at half power is presented. The simulation results show the improved received power distribution and SNR. A VLC system, based on color-shift-keying (CSK) modulation and code-division multiple-access (CDMA) is presented. CSK–CDMA VLC system is used to enhance the VLC system capacity and mitigate single color light interference, which allows multiple users to access the network

    Analysis of Ultra Wide Band (UWB) Technology for an Indoor Geolocation and Physiological Monitoring System

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    The goal of this research is to analyze the utility of UWB for indoor geolocation and to evaluate a prototype system, which will send information detailing a person’s position and physiological status to a command center. In a real world environment, geolocation and physiological status information needs to be sent to a command and control center that may be located several miles away from the operational environment. This research analyzes and characterizes the UWB signal in the various operational environments associated with indoor geolocation. Additionally, typical usage scenarios for the interaction between UWB and other devices are also tested and evaluated

    Wavelet—Artificial Neural Network Receiver for Indoor Optical Wireless Communications

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    The multipath induced intersymbol interference (ISI) and fluorescent light interference (FLI) are the two most important system impairments that affect the performance of indoor optical wireless communication (OWC) systems. The presence of either incurs a high optical power penalty (OPP) and hence the interferences should be mitigated with suitable techniques to ensure optimum system performance. The discrete wavelet transform (DWT) and the artificial neural network (ANN) based receiver to mitigate the effect of FLI and ISI has been proposed in the previous study for the one-off keying (OOK) modulation scheme. It offers performance improvement compared to the traditional methods of employing a high pass filter (HPF) and a finite impulse response (FIR) equalizer. In this paper, the investigation of the DWT-ANN based receiver for baseband modulation techniques including OOK, pulse position modulation (PPM) and digital pulse interval modulation (DPIM) are reported. The proposed system is implemented using digital signal processing (DSP) board and results are verified by comparison with simulation data
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