6,095 research outputs found
Multi Detector Fusion of Dynamic TOA Estimation using Kalman Filter
In this paper, we propose fusion of dynamic TOA (time of arrival) from
multiple non-coherent detectors like energy detectors operating at sub-Nyquist
rate through Kalman filtering. We also show that by using multiple of these
energy detectors, we can achieve the performance of a digital matched filter
implementation in the AWGN (additive white Gaussian noise) setting. We derive
analytical expression for number of energy detectors needed to achieve the
matched filter performance. We demonstrate in simulation the validity of our
analytical approach. Results indicate that number of energy detectors needed
will be high at low SNRs and converge to a constant number as the SNR
increases. We also study the performance of the strategy proposed using IEEE
802.15.4a CM1 channel model and show in simulation that two sub-Nyquist
detectors are sufficient to match the performance of digital matched filter
Approximation of L\"owdin Orthogonalization to a Spectrally Efficient Orthogonal Overlapping PPM Design for UWB Impulse Radio
In this paper we consider the design of spectrally efficient time-limited
pulses for ultrawideband (UWB) systems using an overlapping pulse position
modulation scheme. For this we investigate an orthogonalization method, which
was developed in 1950 by Per-Olov L\"owdin. Our objective is to obtain a set of
N orthogonal (L\"owdin) pulses, which remain time-limited and spectrally
efficient for UWB systems, from a set of N equidistant translates of a
time-limited optimal spectral designed UWB pulse. We derive an approximate
L\"owdin orthogonalization (ALO) by using circulant approximations for the Gram
matrix to obtain a practical filter implementation. We show that the centered
ALO and L\"owdin pulses converge pointwise to the same Nyquist pulse as N tends
to infinity. The set of translates of the Nyquist pulse forms an orthonormal
basis or the shift-invariant space generated by the initial spectral optimal
pulse. The ALO transform provides a closed-form approximation of the L\"owdin
transform, which can be implemented in an analog fashion without the need of
analog to digital conversions. Furthermore, we investigate the interplay
between the optimization and the orthogonalization procedure by using methods
from the theory of shift-invariant spaces. Finally we develop a connection
between our results and wavelet and frame theory.Comment: 33 pages, 11 figures. Accepted for publication 9 Sep 201
Hard-input-hard-output capacity analysis of UWB BPSK systems with timing errors
The hard-input-hard-output capacity of a binary phase-shift keying (BPSK) ultrawideband system is analyzed for both additive white Gaussian noise and multipath fading channels with timing errors. Unlike previous works that calculate the capacity with perfect synchronization and/or multiple-access interference only, our analysis considers timing errors with different distributions, as well as the interpath (IPI), interchip (ICI), and intersymbol (ISI) interferences, as in practical systems. The sensitivity of the channel capacity to the timing error is examined. The effects of pulse shape, the multiple-access technique, the number of users, and the number of chips are studied. It is found that time hopping is less sensitive to the pulse shape and that the timing error has higher capacity than direct sequence due to its low duty of cycle. Using these results, one can choose appropriate system parameters for different applications
An IR-UWB photonic distribution system
Experimental results are presented for a novel distribution system for an impulse radio ultra-wideband (UWB) radio signals employing a gain-switched laser. The pulse position modulated short optical pulses with a bit rate of 1.25 Gb/s are transmitted over fiber to a remote antenna unit, where the signal is converted to the electrical domain and undergoes spectral shaping to remove unwanted components according to UWB requirements. An experimental radio terminal has also been constructed to enable bit-error-rate measurements to be carried out. These experiments show that the optical distribution system will be capable of supporting the radio part of the system
Characterisation of an aperture-stacked patch antenna for ultra-wideband wearable radio systems
This paper presents, for the first time, the time-domain characteristics of an aperture-stacked patch antenna (ASPA) for ultra-wideband (UWB) wearable devices. The methodology of antennas characterization for UWB radio systems is also outlined. The antenna operates within the 3-6 GHz frequency band. Time- and frequency-domain characteristics of this antenna are presented in transmission mode (Tx), receiving mode (Rx) and for 2-antenna (Tx-Rx) system. The pulse driving the antenna has duration of 0.65 ns. In the Tx mode, pulses radiated in different directions of the H-plane have very similar shapes. Fidelity factors are as high as 91.6-99.9%. For 2-antenna system, pulses received in normal and end-fire-like directions have the fidelity of 69.5%. As it was found, antenna does not behave "reciprocal" comparing Tx and Rx modes. For normal propagation direction, radiated pulse is the 2nd derivative of the input waveform, but in the Rx mode, received pulse is the 1st derivative of the incident plane wave. This antenna can be used for transmission of short-pulses, even 0.65-1 ns in duration. It is also small (patch planar dimensions 32/19 mm) and compact. Microstrip configuration allows further integration of active devices on the same board. Taking into account above results we can say that ASPA is a good candidate for UWB non-invasive wireless body area network (WBAN) applications
Highly efficient impulse-radio ultra-wideband cavity-backed slot antenna in stacked air-filled substrate integrated waveguide technology
An impulse-radio ultra-wideband (IR-UWB) cavity-backed slot antenna covering the [5.9803; 6.9989] GHz frequency band of the IEEE 802.15.4a-2011 standard is designed and implemented in an air-filled substrate integrated waveguide (AFSIW) technology for localization applications with an accuracy of at least 3 cm. By relying on both frequency and time-domain optimization, the antenna achieves excellent IR-UWB characteristics. In free-space conditions, an impedance bandwidth of 1.92 GHz (or 29.4%), a total efficiency higher than 89%, a front-to-back ratio of at least 12.1 dB, and a gain higher than 6.3 dBi are measured in the frequency domain. Furthermore, a system fidelity factor larger than 98% and a relative group delay smaller than 100 ps are measured in the time domain within the 3 dB beamwidth of the antenna. As a result, the measured time-of-arrival of a transmitted Gaussian pulse, for different angles of arrival, exhibits variations smaller than 100 ps, corresponding to a maximum distance estimation error of 3 cm. Additionally, the antenna is validated in a real-life worst-case deployment scenario, showing that its characteristics remain stable in a large variety of deployment scenarios. Finally, the difference in frequency-and time-domain performance is studied between the antenna implemented in AFSIW and in dielectric filled substrate integrated waveguide (DFSIW) technology. We conclude that DFSIW technology is less suitable for the envisaged precision IR-UWB localization application
IR-UWB Detection and Fusion Strategies using Multiple Detector Types
Optimal detection of ultra wideband (UWB) pulses in a UWB transceiver
employing multiple detector types is proposed and analyzed in this paper. We
propose several fusion techniques for fusing decisions made by individual
IR-UWB detectors. We assess the performance of these fusion techniques for
commonly used detector types like matched filter, energy detector and amplitude
detector. In order to perform this, we derive the detection performance
equation for each of the detectors in terms of false alarm rate, shape of the
pulse and number of UWB pulses used in the detection and apply these in the
fusion algorithms. We show that the performance can be improved approximately
by 4 dB in terms of signal to noise ratio (SNR) for perfect detectability of a
UWB signal in a practical scenario by fusing the decisions from individual
detectors.Comment: Accepted for publishing in IEEE WCNC 201
A Fully Differential Digital CMOS Pulse UWB Generator
A new fully-digital CMOS pulse generator for impulse-radio Ultra-Wide-Band (UWB) systems is presented. First, the shape of the pulse which best fits the FCC regulation in the 3.1-5 GHz sub-band of the entire 3.1-10.6 GHz UWB bandwidth is derived and approximated using rectangular digital pulses. In particular, the number and width of pulses that approximate an ideal template is found through an ad-hoc optimization methodology. Then a fully differential digital CMOS circuit that synthesizes the pulse sequence is conceived and its functionality demonstrated through post-layout simulations. The results show a very good agreement with the FCC requirements and a low power consumptio
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