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ultra-wideband--uwb
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Noncoherent weighted detection for time reversal UWB systems: Energy and kurtosis detectors
, Article International Journal on Communications Antenna and Propagation ; Volume 1, Issue 2 , 2011 , Pages 174-181 ; 20395086 (ISSN) ; Moghaddam, S. S ; Mohebbi, A ; Abbasi Moghadam, D ; Sharif University of Technology
Praise Worthy Prize S.r.l
Abstract
Time reversal is a technique in which a signal is pre-filtered such that it focuses both in time and space. Spatial focusing reduces interference to other co-existing systems and temporal focusing concentrates the received power in a very short interval. Energy detector is a practical receiver for ultra-wideband (UWB) time reversed signals due to its low-complexity and low-cost implementation. However, selection of an optimum integration interval to minimize the bit error rate is a major problem. Weighted energy detection is an effective technique to overcome this problem and enhance the performance of energy detectors. However, this improvement is achieved at the expense of non-trivial...
Unified structure of basic UWB waveforms
, Article IEEE Transactions on Circuits and Systems II: Express Briefs ; Volume 55, Issue 12 , 2008 , Pages 1304-1308 ; 15497747 (ISSN) ; Amini, A ; Marvasti, F ; Sharif University of Technology
2008
Abstract
In this brief, a generalized expression for the popular ultra wideband waveforms is derived. It is shown that all three waveforms used in ultra wideband (Gaussian, modified Hermite, and prolate spheroidal waveforms) fulfill the Sturm–Liouville differential equation. By using this unified structure, characteristics of the waveforms such as orthogonality, finite duration in time and frequency spectrum are explained. © 2008 IEEE
Upper bounds on the ergodic and outage capacities of relay networks using UWB links
, Article 40th Asilomar Conference on Signals, Systems, and Computers, ACSSC '06, Pacific Grove, CA, 29 October 2006 through 1 November 2006 ; 2006 , Pages 646-650 ; 10586393 (ISSN); 1424407850 (ISBN); 9781424407859 (ISBN) ; Nasiri Kenari, M ; Wehinger, J ; Mecklenbräuker, C. F ; Sharif University of Technology
2006
Abstract
We derive, evaluate, and discuss upper bounds on ergodic and outage capacities for a three-node relay network. The considered relay network has ultra-wideband (UWB) radio channels between the source, destination, and relay nodes. The derived bounds indicate that ergodic and outage capacities of the considered UWB-linked network increase up to 300% when a relay between the source and the destination is used. Furthermore, the bounds indicate that there is an optimum position for the relay node between the source and the destination, where ergodic capacity is maximized. Our numerical results shows that for the non-line-of-sight (NLOS) scenario, with the same signal to noise ratio on all links,...
UWB wireless: A scheme for SCADA communications in offshore wind farms
, Article International Journal of Ultra Wideband Communications and Systems ; Volume 3, Issue 2 , 2015 , Pages 59-67 ; 1758728X (ISSN) ; Talebi, S ; Rashidinejad, M ; Sharif University of Technology
Inderscience Enterprises Ltd
2015
Abstract
Utilisation of reliable communication technologies for data communication is a key challenge in smart grids. Due to specific characteristics of offshore wind farms (OWFs), wireless data communications is of interest for supervisory control and data acquisition (SCADA) communication between wind towers. The ultra-wideband (UWB) communication technology is one of the state-of-the-art communication technologies suitable for inexpensive, low-data rate, outdoor, long-range, communication applications. However, in order to employ it in OWFs, its link modelling and performance must first be well analysed comprehensively. In this paper, the UWB communication channel is modelled in OWFs and with...
Design of an UWB Analogue Detector Receiver for Biomedical Applications
, M.Sc. Thesis Sharif University of Technology ; Sharifkhani, Mohammad (Supervisor) ; Fotowat-Ahmady, Ali (Co-Advisor)
Abstract
Emergence of the implantable biomedical microsystems and personal area networks in recent years result in a new class of biomedical systems that requires data transmition in short range at various data rates. Performing with ultra low power consumption and long battery life are crucial in these systems. Therefore, designing low power radios for these systems is still an active research area. Ultera wideband systems are specially considered for implementations because of their potential characteristics.
In this dissertation, different biomedical applications and data communication approaches are surveyed. Then, Different architectures of UWB receivers are reviewed. To implement a low...
In this dissertation, different biomedical applications and data communication approaches are surveyed. Then, Different architectures of UWB receivers are reviewed. To implement a low...
Performance analysis and comparisons of different ultra-wideband multiple access modulation schemes
, Article IEE Proceedings: Communications ; Volume 153, Issue 5 , 2006 , Pages 705-718 ; 13502425 (ISSN) ; Nasiri Kenari, M ; Sharif University of Technology
2006
Abstract
The multiuser performance of two kinds of ultra-wideband (UWB) systems, namely, multi-carrier frequency-hopping-UWB and time-hopping-UWB, is evaluated. We derive the bit error rate of these systems in both AWGN and fading channels. Our numerical results show that the TH-UWB system always outperforms the MC-FH-UWB system with non-coherent detection. However, the MC-FH-UWB system with coherent detection presents a better performance than TH-UWB in a very few cases. Then, we use a practical low-rate convolutional error correcting code, which does not require any extra bandwidth further than that needed by the uncoded scheme, to improve the system performance. The results show that the coded...
Robust Wiener filter-based time gating method for detection of shallowly buried objects
, Article IET Signal Processing ; 2021 ; 17519675 (ISSN) ; Behnia, F ; Shokouhmand, A ; Shaker, G ; Sharif University of Technology
Institution of Engineering and Technology
2021
Abstract
A robust method for ultra-wideband (UWB) imaging of buried shallow objects based on time gating, Wiener filtering, as well as constant false alarm rate (CFAR) is proposed. Moreover, it is demonstrated that Wiener filtering can be used as a clutter removal tool in UWB signal applications. Basically, the problem with time gating method is that the length of the timing window for unknown targets cannot be determined accurately in advance. In fact, it is a blind methodology and some targets can be missed due to a lack of pre-knowledge about their depth. Imprecise window length selection leads to missing some parts of the target signals along with the clutter, which in turn increases the missed...
PPM-UWB channel modeling for SCADA communications in offshore wind farms
, Article 2012 2nd Iranian Conference on Smart Grids, ICSG 2012, 23 May 2012 through 24 May 2012 ; May , 2012 , Page(s): 1 - 6 ; 9781467313995 (ISBN) ; Talebi, S ; Rashidinejad, M ; Rashidinejad, A ; Sharif University of Technology
IEEE
2012
Abstract
In smart grid research and particularly Offshore Wind Farms (OWFs), employing wireless data communications as a reliable technology for Supervisory Control and Data Acquisition (SCADA) communication between wind towers is of great interest. This paper introduces the Ultra-Wideband (UWB) communication system based on Pulse Position Modulation (PPM) for this intention. In this work, the UWB link is modeled in WOFs and performance of the UWB link subject to several metrics such as range-data rate, range-bit error rate (BER), and path loss are systematically and arithmetically assessed. The results prove UWB system as a promising inexpensive, but high performance approach for wireless SCADA...
Design and Simulation of an UWB RFID Reader
, M.Sc. Thesis Sharif University of Technology ; Fotowat Ahmady, Ali (Supervisor)
Abstract
Ultra-wideband (UWB) frequencies with low level of power spectral density, which is set by FCC standard, have long been utilized in many short range applications, namely sensor networks, indoor positioning and radar systems. As their name suggests, the ultra-wide bandwidth of this standard, covering frequencies from 3.1 to 10.6GHz, provides high data rate communications. Two of the most critical challenges toward UWB receiver design is narrow-band interference coexistence, including IEEE802.11a and jitter due to the very narrow width of the UWB pulse in time domain. General previously proposed solutions to receive these narrow pulses is based on correlation principle, which is very sensitive...
A 90 nm-CMOS IR-UWB BPSK transmitter with spectrum tunability to improve peaceful UWB-narrowband coexistence
, Article IEEE Transactions on Circuits and Systems I: Regular Papers ; Vol. 61, issue. 6 , January , 2014 , p. 1836-1848 ; 15498328 ; Fotowat-Ahmady, A ; Nezhad, A. Z ; Serdijn, W. A ; Sharif University of Technology
Abstract
A new ultra wideband (UWB) pulse generator covering a-10 dB bandwidth of 2.4-4.6 GHz with a tunable center frequency of 5-5.6 GHz to mitigate coexistence issues of impulse radio UWB (IR-UWB) systems and IEEE802.11.a WLAN or other narrowband (NB) systems in 90 nm-CMOS technology is proposed. The UWB pulse is generated based on frequency up-conversion of the first derivative of the Gaussian pulse, which creates an adjustable null in the frequency spectrum. Simulation results show that employing the proposed pulse generator mitigates the mutual interference between UWB and WLAN systems, significantly. The proposed transmitter consists of a low frequency signal generator, an LC oscillator and a...
Broadband miniaturized efficient array antennas
, Article Applied Computational Electromagnetics Society Journal ; Volume 28, Issue 3 , 2013 , Pages 188-194 ; 10544887 (ISSN) ; Jafargholi, A ; Sharif University of Technology
2013
Abstract
This paper introduces a new array architecture, in which antenna elements are arranged in a spiral curve. The spiral array enhances ultra-wideband (UWB) pattern characteristics compared to alternative array geometries of similar elements, without requiring a complex feed network for frequency change compensation. A number of examples are illustrated to demonstrate the array capability in broadband array designs. It is revealed that for the same number of elements and curvature lengths, a spiral array has a wider radiation bandwidth than the corresponding circular and linear array antennas. In addition, it is also demonstrated that the spiral architecture discussed here can be best suited for...
An ultra-wideband 3-dB quadrature hybrid with multisection broadside stripline tandem structure
, Article Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering ; Volume 77 LNICST , 2012 , Pages 672-681 ; 18678211 (ISSN) ; 9783642351549 (ISBN) ; Majedi, S. M. S ; Farzaneh, F ; Sharif University of Technology
2012
Abstract
Design of an Ultra-Wideband 3-dB quadrature (90°) Hybrid using ADS and HFSS softwares plus Measurement report are presented. Simultaneous Use of these two softwares lead to fast and accurate design procedure. The coupler is realized in broadside stripline and with the connection of coupled regions in tandem structure. The measured data agrees well with the expected values from simulations, and shows a good ultra wide bandwidth response over the frequency range of 1-10 GHz. Measurements showed an amplitude unbalance of ±1.5 dB, a phase unbalance of 90°±7° , and an isolation and a return loss characteristics of more than 14 dB over the frequency of 1 to 10 GHz
Using cubic B-spline interpolation for efficient ray-tracing-based ultrawideband propagation modeling
, Article Proceedings - IEEE International Conference on Ultra-Wideband, 14 September 2011 through 16 September 2011, Bologna ; 2011 , Pages 12-15 ; 21626588 (ISSN) ; 9781457717642 (ISBN) ; Shishegar, A. A ; Sharif University of Technology
Abstract
Site-specific ultrawideband propagation modeling involves dealing with frequency variations of the propagation mechanisms and antenna patterns in the ray tracing program. Typically, electromagnetic field calculations have to be performed in a lot of frequencies to accurately construct the frequency response of the channel at a receiving point. This imposes a heavy computational burden on ray tracing specially in calculating the coverage map or finding the statistics of channel parameters where the number of receiving locations is large. In this paper, the computational complexity of ray tracing in ultrawideband propagation modeling is reduced by using cubic B-spline interpolation. The...
A unified solution for super-regenerative systems with application to correlator-based uwb tran
, Article IEEE Transactions on Circuits and Systems I: Regular Papers ; Volume 62, Issue 4 , March , 2015 , Pages 1033-1041 ; 15498328 (ISSN) ; Sharifkhani, M ; Fotowat Ahmady, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
The conventional theory of super regenerative systems (SRS) has been divided into distinct modes of operation and limiting assumptions. These assumptions make the analysis of these systems inaccurate for wide bandwidth applications. In this paper, a novel theory based on the analysis of time varying systems using Magnus expansion is proposed which unifies all modes of operation and formulates the system response with high accuracy for a wide range of practical applications. Therefore, the theory can be used for the design of systems with wider bandwidth and higher data rates. Using the proposed theory, it is possible to analytically describe the effects of the parasitic elements and inter...
Indoor ultrawideband propagation modelling using Chebyshev interpolation in 60 GHz band based on ray tracing technique
, Article Conference on Millimeter-Wave and Terahertz Technologies, MMWaTT, 30 December 2014 through 1 January 2015 ; Volume 2015-March , December-January , 2015 ; 21570965 (ISSN) ; 9781479965915 (ISBN) ; Shishegar, A. A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
An efficient ray tracing technique for channel modeling of an ultrawideband signal in 60 GHz band is introduced. In the usual method, field calculations at many frequencies must be done where has a high computational cost. We have introduced a novel method using Chebyshev polynomials interpolation to reduce the computational cost. Some propagation parameters such as gain and root mean square (RMS) delay spread are obtained and compared to the other method
Design of mid-infrared ultra-wideband metallic absorber based on circuit theory
, Article Optics Communications ; Volume 381 , 2016 , Pages 309-313 ; 00304018 (ISSN) ; Abdollahramezani, S ; Farajollahi, S ; Khavasi, A ; Rejaei, B ; Sharif University of Technology
Elsevier B.V
2016
Abstract
An ultra-broadband absorber of light is proposed by using periodic array of ultra-thin metallic ribbons on top of a lossless quarter-wavelength dielectric spacer placed on a metallic reflector. We propose a fully analytical circuit model for the structure, and then the absorber is duly designed based on the impedance matching concept. As a result, normalized bandwidth of 99.5% is realized by the proposed absorbing structure in mid-infrared regime. Performing a numerical optimization algorithm, we could also reach to normalized bandwidth of 103%
Code-shifted reference for internally coded time hopping UWB communication system
, Article 2008 International Symposium on Telecommunications, IST 2008, Tehran, 27 August 2008 through 28 August 2008 ; 2008 , Pages 214-218 ; 9781424427512 (ISBN) ; Nasiri Kenari, M ; Sharif University of Technology
2008
Abstract
In this paper, we consider a code-shifted reference (CSR) for the previously introduced internally coded time hopping UWB communication systems in order to avoid channel estimation. We evaluate the performance of our proposed scheme and compare the results with those of the uncoded coded-shifted reference (CSR) UWB system. Our numerical results show the substantial performance improvement when using the proposed scheme compared to the uncoded CSR system. ©2008 IEEE
A new IR-UWB pulse to mitigate coexistence issues of UWB and narrowband systems
, Article 2013 21st Iranian Conference on Electrical Engineering ; May , 2013 , Page(s): 1 - 5 ; 9781467356343 (ISBN) ; Nezhad, A. Z ; Fotowat Ahmady, A ; Sharif University of Technology
2013
Abstract
A new Ultra Wideband (UWB) pulse shape is proposed to mitigate coexistence issues of IEEE802.11.a WLAN and Impulse Radio UWB (IR-UWB) systems. The proposed method is applicable to the reduction of any given narrowband (NB) interference into UWB systems. This pulse shape is based on frequency up-converting of first derivative of Gaussian pulse which has an adjustable null in Power Spectral Density (PSD) depending on up-converting frequency. Both analytical and simulation results with an adaptive receiver show that an UWB system with interference from a WLAN has noticeable improved performance when using the proposed pulse in comparison with using conventional modulated Gaussian pulse
Modeling beacon period length of the UWB and 60-GHz mmWave WPANs based on ECMA-368 and ECMA-387 standards
, Article IEEE Transactions on Mobile Computing ; Volume 12, Issue 6 , 2013 , Pages 1201-1213 ; 15361233 (ISSN) ; Manzuri Shalmani, M. T ; Sharif University of Technology
2013
Abstract
To evaluate the performance of the distributed medium access control layer of the emerging ultrawideband and 60-GHz millimeter wave (mmWave) wireless personal area networks based on ECMA-368 and ECMA-387 standards, the first step is to determine the beacon period length (BPL) of the superframe in a given network. In this paper, we provide an analytical model for the probability mass function (PMF) of the BPL as a function of the network dimensions, number of beaconing devices, antenna beamwidth, and the transmission range of the devices. To enable devices with steerable directional antennas in the ECMA-387 standard to have simultaneous communications with neighbors in their different antenna...
Modeling the beaconing mechanism in short range wireless networks based on the DRP protocol in outdoor environments
, Article Wireless Personal Communications ; Volume 70, Issue 2 , 2013 , Pages 831-846 ; 09296212 (ISSN) ; Manzuri Shalmani, M. T ; Sharif University of Technology
2013
Abstract
A probabilistic method is developed here to model the beacon period length (BPL) defined in the ECMA-368 and ECMA-387 standards for the distributed reservation protocol. The model computes the probability mass function (PMF) of the BPL in a superframe which will be used in modeling of throughput, delay, fairness, power and other major distributed medium access control layer parameters of the emerging ultra wideband and 60- GHz millimeter wave wireless personal area networks. The model relates the PMF of the BPL to the network density, antenna beamwidth, and the transmission range of the devices assuming that the devices are distributed in an outdoor environment based on Two-dimensional...