3,926 research outputs found
Ranging in a single-input multiple-output (SIMO) system
Cataloged from PDF version of article.In this letter, optimal ranging in a single-input
multiple-output (SIMO) system is studied. The theoretical limits
on the accuracy of time-of-arrival (TOA) (equivalently, range)
estimation are calculated in terms of the Cramer-Rao lower
bound (CRLB). Unlike the conventional phased array antenna
structure, a more generic fading model is employed, which allows
for the analysis of spatial diversity gains from the viewpoint of
a ranging system. In addition to the optimal solution, a two-step
suboptimal range estimator is proposed, and its performance is
compared with the CRLBs
Spatial Identification Methods and Systems for RFID Tags
DisertaÄŤnĂ práce je zaměřena na metody a systĂ©my pro měřenĂ vzdálenosti a lokalizaci RFID tagĹŻ pracujĂcĂch v pásmu UHF. Ăšvod je vÄ›nován popisu souÄŤasnĂ©ho stavu vÄ›deckĂ©ho poznánĂ v oblasti RFID prostorovĂ© identifikace a struÄŤnĂ©mu shrnutĂ problematiky modelovánĂ a návrhu prototypĹŻ tÄ›chto systĂ©mĹŻ. Po specifikaci cĂlĹŻ disertace pokraÄŤuje práce popisem teorie modelovánĂ degenerovanĂ©ho kanálu pro RFID komunikaci. DetailnÄ› jsou rozebrány metody měřenĂ vzdálenosti a odhadu smÄ›ru pĹ™Ăchodu signálu zaloĹľenĂ© na zpracovánĂ fázovĂ© informace. Pro účely lokalizace je navrĹľeno nÄ›kolik scĂ©nářů rozmĂstÄ›nĂ antĂ©n. Modely degenerovanĂ©ho kanálu jsou simulovány v systĂ©mu MATLAB. VĂ˝znamná část tĂ©to práce je vÄ›nována konceptu softwarovÄ› definovanĂ©ho rádia (SDR) a specifikĹŻm jeho adaptace na UHF RFID, která vyuĹľitĂ běžnĂ˝ch SDR systĂ©mĹŻ znaÄŤnÄ› omezujĂ. Diskutována je zejmĂ©na problematika prĹŻniku nosnĂ© vysĂlaÄŤe do pĹ™ijĂmacĂ cesty a poĹľadavky na signál lokálnĂho oscilátoru pouĹľĂvanĂ˝ pro směšovánĂ. Prezentovány jsou tĹ™i vyvinutĂ© prototypy: experimentálnĂ dotazovaÄŤ EXIN-1, měřicĂ systĂ©m zaloĹľenĂ˝ na platformÄ› Ettus USRP a antĂ©nnĂ pĹ™epĂnacĂ matice pro emulaci SIMO systĂ©mu. ZávÄ›reÄŤná část je zaměřena na testovánĂ a zhodnocenĂ popisovanĂ˝ch lokalizaÄŤnĂch technik, zaloĹľenĂ˝ch na měřenĂ komplexnĂ pĹ™enosovĂ© funkce RFID kanálu. Popisuje ĂşzkopásmovĂ©/širokopásmovĂ© měřenĂ vzdálenosti a metody odhadu smÄ›ru signálu. Oba navrĹľenĂ© scĂ©náře rozmĂstÄ›nĂ antĂ©n jsou v závÄ›ru ověřeny lokalizaÄŤnĂm měřenĂm v reálnĂ˝ch podmĂnkách.The doctoral thesis is focused on methods and systems for ranging and localization of RFID tags operating in the UHF band. It begins with a description of the state of the art in the field of RFID positioning with short extension to the area of modeling and prototyping of such systems. After a brief specification of dissertation objectives, the thesis overviews the theory of degenerate channel modeling for RFID communication. Details are given about phase-based ranging and direction of arrival finding methods. Several antenna placement scenarios are proposed for localization purposes. The degenerate channel models are simulated in MATLAB. A significant part of the thesis is devoted to software defined radio (SDR) concept and its adaptation for UHF RFID operation, as it has its specialties which make the usage of standard SDR test equipment very disputable. Transmit carrier leakage into receiver path and requirements on local oscillator signals for mixing are discussed. The development of three experimental prototypes is also presented there: experimental interrogator EXIN-1, measurement system based on Ettus USRP platform, and antenna switching matrix for an emulation of SIMO system. The final part is focused on testing and evaluation of described positioning techniques based on complex backscatter channel transfer function measurement. Both narrowband/wideband ranging and direction of arrival methods are validated. Finally, both proposed antenna placement scenarios are evaluated with real-world measurements.
Nonlinear structural damage detection based on cascade of Hammerstein models
Structural damages can result in nonlinear dynamical signatures that can significantly enhance their detection. An original nonlinear damage detection approach is proposed that is based on a cascade of Hammerstein models representation of the structure. This model is estimated by means of the Exponential Sine Sweep Method from only one measurement. On the basis of this estimated model, the linear and nonlinear parts of the output are estimated, and two damage indexes (DIs) are proposed. The first DI is built as the ratio of the energy contained in the nonlinear part of an output versus the energy contained in its linear part. The second DI is the angle between the subspaces obtained from the nonlinear parts of two set of outputs after a principal component analysis. The sensitivity of the proposed DIs to the presence of damages as well as their robustness to noise are assessed numerically on spring-mass-damper structures and experimentally on actual composite plates with surface-mounted PZT-elements. Results demonstrate the effectiveness of the proposed method to detect a damage in nonlinear structures and in the presence of noise
Multipath Multiplexing for Capacity Enhancement in SIMO Wireless Systems
This paper proposes a novel and simple orthogonal faster than Nyquist (OFTN)
data transmission and detection approach for a single input multiple output
(SIMO) system. It is assumed that the signal having a bandwidth is
transmitted through a wireless channel with multipath components. Under
this assumption, the current paper provides a novel and simple OFTN
transmission and symbol-by-symbol detection approach that exploits the
multiplexing gain obtained by the multipath characteristic of wideband wireless
channels. It is shown that the proposed design can achieve a higher
transmission rate than the existing one (i.e., orthogonal frequency division
multiplexing (OFDM)). Furthermore, the achievable rate gap between the proposed
approach and that of the OFDM increases as the number of receiver antennas
increases for a fixed value of . This implies that the performance gain of
the proposed approach can be very significant for a large-scale multi-antenna
wireless system. The superiority of the proposed approach is shown
theoretically and confirmed via numerical simulations. {Specifically, we have
found {upper-bound average} rates of 15 bps/Hz and 28 bps/Hz with the OFDM and
proposed approaches, respectively, in a Rayleigh fading channel with 32 receive
antennas and signal to noise ratio (SNR) of 15.3 dB. The extension of the
proposed approach for different system setups and associated research problems
is also discussed.Comment: IEEE Transactions on Wireless Communication
Single-input Multiple-output Tunable Log-domain Current-mode Universal Filter
This paper describes the design of a current-mode single-input multiple-output (SIMO) universal filter based on the log-domain filtering concept. The circuit is a direct realization of a first-order differential equation for obtaining the lossy integrator circuit. Lossless integrators are realized by log-domain lossy integrators. The proposed filter comprises only two grounded capacitors and twenty-four transistors. This filter suits to operate in very high frequency (VHF) applications. The pole-frequency of the proposed filter can be controlled over five decade frequency range through bias currents. The pole-Q can be independently controlled with the pole-frequency. Non-ideal effects on the filter are studied in detail. A validated BJT model is used in the simulations operated by a single power supply, as low as 2.5 V. The simulation results using PSpice are included to confirm the good performances and are in agreement with the theory
The need of modeling: Experience from the Samothraki Summer University
Postprint (published version
Advanced Radio Resource Management for Multi Antenna Packet Radio Systems
In this paper, we propose fairness-oriented packet scheduling (PS) schemes
with power-efficient control mechanism for future packet radio systems. In
general, the radio resource management functionality plays an important role in
new OFDMA based networks. The control of the network resource division among
the users is performed by packet scheduling functionality based on maximizing
cell coverage and capacity satisfying, and certain quality of service
requirements. Moreover, multiantenna transmit-receive schemes provide
additional flexibility to packet scheduler functionality. In order to mitigate
inter-cell and co-channel interference problems in OFDMA cellular networks soft
frequency reuse with different power masks patterns is used. Stemming from the
earlier enhanced proportional fair scheduler studies for single-input
multiple-output (SIMO) and multiple-input multipleoutput (MIMO) systems, we
extend the development of efficient packet scheduling algorithms by adding
transmit power considerations in the overall priority metrics calculations and
scheduling decisions. Furthermore, we evaluate the proposed scheduling schemes
by simulating practical orthogonal frequency division multiple access (OFDMA)
based packet radio system in terms of throughput, coverage and fairness
distribution among users. As a concrete example, under reduced overall transmit
power constraint and unequal power distribution for different sub-bands, we
demonstrate that by using the proposed power-aware multi-user scheduling
schemes, significant coverage and fairness improvements in the order of 70% and
20%, respectively, can be obtained, at the expense of average throughput loss
of only 15%.Comment: 14 Pages, IJWM
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