36 research outputs found

    Low-complexity high-performance GFSK receiver with carrier frequency offset correction

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    This paper presents an implementation of a GFSK receiver based on matched filtering of a sequence of K successive bits. This enables improved detection and superior BER performance but requires 2K matched filters of considerable complexity. Exploiting redundancy by performing phase propagation of successive single-bit stages, we propose an efficient receiver implementation. Results presented highlight the benefits of the proposed methd in terms of computational cost and performance compared to standard methods. We also address carrier frequency offset, and suggest a blind algorithm for its elimination. Performance results are exemplarily shown for a Bluetooth system

    Capacity -based parameter optimization of bandwidth constrained CPM

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    Continuous phase modulation (CPM) is an attractive modulation choice for bandwidth limited systems due to its small side lobes, fast spectral decay and the ability to be noncoherently detected. Furthermore, the constant envelope property of CPM permits highly power efficient amplification. The design of bit-interleaved coded continuous phase modulation is characterized by the code rate, modulation order, modulation index, and pulse shape. This dissertation outlines a methodology for determining the optimal values of these parameters under bandwidth and receiver complexity constraints. The cost function used to drive the optimization is the information-theoretic minimum ratio of energy-per-bit to noise-spectral density found by evaluating the constrained channel capacity. The capacity can be reliably estimated using Monte Carlo integration. A search for optimal parameters is conducted over a range of coded CPM parameters, bandwidth efficiencies, and channels. Results are presented for a system employing a trellis-based coherent detector. To constrain complexity and allow any modulation index to be considered, a soft output differential phase detector has also been developed.;Building upon the capacity results, extrinsic information transfer (EXIT) charts are used to analyze a system that iterates between demodulation and decoding. Convergence thresholds are determined for the iterative system for different outer convolutional codes, alphabet sizes, modulation indices and constellation mappings. These are used to identify the code and modulation parameters with the best energy efficiency at different spectral efficiencies for the AWGN channel. Finally, bit error rate curves are presented to corroborate the capacity and EXIT chart designs

    Analysis, Modeling and Testing of a Multi-Receiver Wireless System for Telemetry Applications

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    This thesis investigates the potential value of multiple co-located receiver units for telemetry applications. In this thesis, a test board based on the NRF24L01 RF chip produced by Nordic Semiconductor was tested. Testing consisted of sending pseudo-random test data over a link between two test boards at progressive distances. Packet loss rate was identified as the dominant failure mode of the chip, and was used to determine performance increase. A parametric model of the chip performance was developed based on coherent and noncoherent FSK detectors and curve fit to the experimental data to model the performance of a single GFSK receiver with unknown parameters. The chip exhibited an estimated 10 fold improvement in bit error performance at short range, with the performance improvement dropping off as distance increased. This result implies that there may be significant utility to using multiple receiver systems when traditional methods of improving performance such as amplifiers and antennas do not provide the necessary benefit

    UWB System Based on Energy Detection of Derivatives of The Gaussian Pulse

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    A new method for energy detection ultra-wideband systems is proposed. The transmitter of this method uses two pulses that are different-order derivatives of the Gaussian pulse to transmit bit 0 or 1. These pulses are appropriately chosen to separate their spectra in the frequency domain. The receiver is composed of two energydetection branches. Each branch has a filter which captures the signal energy of either bit 0 or 1. The outputs of the two branches are subtracted from each other to generate the decision statistic. The value of this decision statistic is compared to the threshold to determine the transmitted bit. This new method has the same bit error rate (BER) performance as energy detection-based pulse position modulation (PPM) in additive white Gaussian noise channels. In multipath channels, its performance surpasses PPM and it also exhibits better BER performance in the presence of synchronization errors

    Modulation and Multiple Access Techniques for Ultra-Wideband Communication Systems

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    Two new energy detection (ED) Ultra-Wideband (UWB) systems are proposed in this dissertation. The first one is an ED UWB system based on pulse width modulation (PWM). The bit error rate (BER) performance of this ED PWM system is slightly worse than ED pulse position modulation (PPM) system in additive white Gaussian noise (AWGN) channels. However, the BER performance of this ED PWM system surpasses that of a PPM system in multipath channels since a PWM system does not suffer cross-modulation interference (CMI) as a PPM system. In the presence of synchronization errors, the BER performance of a PWM system also surpasses that of a PPM system. The second proposed ED UWB system is based on using two pulses, which are the different-order derivatives of the Gaussian pulse, to transmitted bit 0 or 1. These pulses are appropriately chosen to separate their spectra in frequency domain.The receiver is composed of two energy detection branches and each branch has a filter which captures the signal energy of either bit 0 or 1. The outputs of two branches are subtracted from each other to generate the decision statistic and the value of this statistic is compared to a threshold to determine the transmitted bits. This system is named as acf{GFSK} system in this dissertation and it exhibits the same BER performance as a PPM system in AWGN channels. In multipath channels, a GFSK system surpasses a PPM system because it does not suffer CMI. And the BER performance of a GFSK system is better than a PPM system in the presence of synchronization errors. When a GFSK system is compared to a PWM system, it will always achieve approximately 2 dB improvement in AWGN channels, multipath channels, and in the presence synchronization errors. However, a PWM system uses lower-order derivatives of the Gaussian pulse to transmit signal, and this leads to a simple pulse generator. In this dissertation, an optimal threshold is applied to improve PPM system performance. The research results show that the application of an optimal threshold can e

    Modulation and Multiple Access Techniques for Ultra-Wideband Communication Systems

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    Two new energy detection (ED) Ultra-Wideband (UWB) systems are proposed in this dissertation. The first one is an ED UWB system based on pulse width modulation (PWM). The bit error rate (BER) performance of this ED PWM system is slightly worse than ED pulse position modulation (PPM) system in additive white Gaussian noise (AWGN) channels. However, the BER performance of this ED PWM system surpasses that of a PPM system in multipath channels since a PWM system does not suffer cross-modulation interference (CMI) as a PPM system. In the presence of synchronization errors, the BER performance of a PWM system also surpasses that of a PPM system. The second proposed ED UWB system is based on using two pulses, which are the different-order derivatives of the Gaussian pulse, to transmitted bit 0 or 1. These pulses are appropriately chosen to separate their spectra in frequency domain.The receiver is composed of two energy detection branches and each branch has a filter which captures the signal energy of either bit 0 or 1. The outputs of two branches are subtracted from each other to generate the decision statistic and the value of this statistic is compared to a threshold to determine the transmitted bits. This system is named as acf{GFSK} system in this dissertation and it exhibits the same BER performance as a PPM system in AWGN channels. In multipath channels, a GFSK system surpasses a PPM system because it does not suffer CMI. And the BER performance of a GFSK system is better than a PPM system in the presence of synchronization errors. When a GFSK system is compared to a PWM system, it will always achieve approximately 2 dB improvement in AWGN channels, multipath channels, and in the presence synchronization errors. However, a PWM system uses lower-order derivatives of the Gaussian pulse to transmit signal, and this leads to a simple pulse generator. In this dissertation, an optimal threshold is applied to improve PPM system performance. The research results show that the application of an optimal threshold can e

    Analytical and empirical evaluation of the impact of Gaussian noise on the modulations employed by Bluetooth Enhanced Data Rates

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    Bluetooth (BT) is a leading technology for the deployment of wireless Personal Area Networks and Body Area Networks. Versions 2.0 and 2.1 of the standard, which are massively implemented in commercial devices, improve the throughput of the BT technology by enabling the so-called Enhanced Data Rates (EDR). EDRs are achieved by utilizing new modulation techniques (π/4-DQPSK and 8-DPSK), apart from the typical Gaussian Frequency Shift Keying modulation supported by previous versions of BT. This manuscript presents and validates a model to characterize the impact of white noise on the performance of these modulations. The validation is systematically accomplished in a testbed with actual BT interfaces and a calibrated white noise generator.Ministerio de Educación y Ciencia TEC2009-13763-C02-0

    A characterization of the performance of Bluetooth 2.x + EDR technology in noisy environments

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    Bluetooth (BT) is by far the most popular shortrange technology for the development of wireless personal area networks and body area networks. Nowadays, BT 2.0 and 2.1 ? EDR are the most extended and implemented versions of BT standard. This article presents an analytical model that computes the packet delay of transmissions that utilize this version of BT in noisy environments. The model, which takes into account the packet retransmissions caused by noise, is particularized to calculate the mean packet delay as a function of the signal-to-noise ratio for the different enhanced data rates provided by BT 2.0 and 2.1 specifications. Thus, the model permits evaluating the efficiency of using these enhanced rates in the presence of a certain noise level.Ministerio de Ciencia e Innovación TEC2009-13763-C02-01Ministerio de Ciencia e Innovación TEC2013-42711-
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