34,665 research outputs found
Spatial Identification Methods and Systems for RFID Tags
DisertaÄnĂ prĂĄce je zamÄĆena na metody a systĂ©my pro mÄĆenĂ vzdĂĄlenosti a lokalizaci RFID tagĆŻ pracujĂcĂch v pĂĄsmu UHF. Ăvod je vÄnovĂĄn popisu souÄasnĂ©ho stavu vÄdeckĂ©ho poznĂĄnĂ v oblasti RFID prostorovĂ© identifikace a struÄnĂ©mu shrnutĂ problematiky modelovĂĄnĂ a nĂĄvrhu prototypĆŻ tÄchto systĂ©mĆŻ. Po specifikaci cĂlĆŻ disertace pokraÄuje prĂĄce popisem teorie modelovĂĄnĂ degenerovanĂ©ho kanĂĄlu pro RFID komunikaci. DetailnÄ jsou rozebrĂĄny metody mÄĆenĂ vzdĂĄlenosti a odhadu smÄru pĆĂchodu signĂĄlu zaloĆŸenĂ© na zpracovĂĄnĂ fĂĄzovĂ© informace. Pro ĂșÄely lokalizace je navrĆŸeno nÄkolik scĂ©nĂĄĆĆŻ rozmĂstÄnĂ antĂ©n. Modely degenerovanĂ©ho kanĂĄlu jsou simulovĂĄny v systĂ©mu MATLAB. VĂœznamnĂĄ ÄĂĄst tĂ©to prĂĄce je vÄnovĂĄna konceptu softwarovÄ definovanĂ©ho rĂĄdia (SDR) a specifikĆŻm jeho adaptace na UHF RFID, kterĂĄ vyuĆŸitĂ bÄĆŸnĂœch SDR systĂ©mĆŻ znaÄnÄ omezujĂ. DiskutovĂĄna je zejmĂ©na problematika prĆŻniku nosnĂ© vysĂlaÄe do pĆijĂmacĂ cesty a poĆŸadavky na signĂĄl lokĂĄlnĂho oscilĂĄtoru pouĆŸĂvanĂœ pro smÄĆĄovĂĄnĂ. PrezentovĂĄny jsou tĆi vyvinutĂ© prototypy: experimentĂĄlnĂ dotazovaÄ EXIN-1, mÄĆicĂ systĂ©m zaloĆŸenĂœ na platformÄ Ettus USRP a antĂ©nnĂ pĆepĂnacĂ matice pro emulaci SIMO systĂ©mu. ZĂĄvÄreÄnĂĄ ÄĂĄst je zamÄĆena na testovĂĄnĂ a zhodnocenĂ popisovanĂœch lokalizaÄnĂch technik, zaloĆŸenĂœch na mÄĆenĂ komplexnĂ pĆenosovĂ© funkce RFID kanĂĄlu. Popisuje ĂșzkopĂĄsmovĂ©/ĆĄirokopĂĄsmovĂ© mÄĆenĂ vzdĂĄlenosti a metody odhadu smÄru signĂĄlu. Oba navrĆŸenĂ© scĂ©nĂĄĆe rozmĂstÄnĂ antĂ©n jsou v zĂĄvÄru ovÄĆeny lokalizaÄnĂm mÄĆenĂm v reĂĄlnĂœch podmĂnkĂĄch.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.
Power-Based Direction-of-Arrival Estimation Using a Single Multi-Mode Antenna
Phased antenna arrays are widely used for direction-of-arrival (DoA)
estimation. For low-cost applications, signal power or received signal strength
indicator (RSSI) based approaches can be an alternative. However, they usually
require multiple antennas, a single antenna that can be rotated, or switchable
antenna beams. In this paper we show how a multi-mode antenna (MMA) can be used
for power-based DoA estimation. Only a single MMA is needed and neither
rotation nor switching of antenna beams is required. We derive an estimation
scheme as well as theoretical bounds and validate them through simulations. It
is found that power-based DoA estimation with an MMA is feasible and accurate
Performance of Angle of Arrival Detection Using MUSIC Algorithm in Inter-Satellite Link
An attitude of satellite is not always static, sometimes it moves randomly
and the antenna pointing of satellite is harder to achieve line of sight
communication to other satellite when it is outage by tumbling effect. In order
to determine an appropriate direction of satellite antenna in inter-satellite
link, this paper analyze estimation performance of the direction of arrival
(DoA) using MUSIC algorithm from connected satellite signal source. It differs
from optical measurement, magnetic field measurement, inertial measurement, and
global positioning system (GPS) attitude determination. The proposed method is
characterized by taking signal source from connected satellites, after that the
main satellite processed the information to obtain connected satellites antenna
direction. The simulation runs only on the direction of azimuth. The simulation
result shows that MUSIC algorithm processing time is faster than satellite
movement time in orbit on altitude of 830 km with the period of 101 minutes.
With the use of a 50 elements array antenna in spacing of 0.5 wavelength, the
total of 20 angle of arrival (AoA) can be detected in 0.98 seconds of
processing time when using MUSIC algorithm
Simulation of Multi-element Antenna Systems for Navigation Applications
The application of user terminals with multiple antenna inputs for use with the global satellite navigation systems like GPS and Galileo becomes more and more attraction in last years. Multiple antennas may be spread over the user platform and provide signals required for the platform attitude estimation or may be arranged in an antenna array to be used together with array processing algorithms for improving signal reception, e.g. for multipath and interference mitigation. In order to generate signals for testing of receivers with multiple antenna inputs and corresponding receiver algorithms in a laboratory environment a unique HW signal simulation tool for wavefront simulation has been developed. The signals for a number of antenna elements in a flexible user defined geometry are first generated as digital signals in baseband and then mixed up to individual RF-outputs. The paper describes the principle function of the system and addresses some calibration issues. Measurement set-ups and results of data processing with simulated signals for different applications are shown and discussed
Linear Block Coding for Efficient Beam Discovery in Millimeter Wave Communication Networks
The surge in mobile broadband data demands is expected to surpass the
available spectrum capacity below 6 GHz. This expectation has prompted the
exploration of millimeter wave (mm-wave) frequency bands as a candidate
technology for next generation wireless networks. However, numerous challenges
to deploying mm-wave communication systems, including channel estimation, need
to be met before practical deployments are possible. This work addresses the
mm-wave channel estimation problem and treats it as a beam discovery problem in
which locating beams with strong path reflectors is analogous to locating
errors in linear block codes. We show that a significantly small number of
measurements (compared to the original dimensions of the channel matrix) is
sufficient to reliably estimate the channel. We also show that this can be
achieved using a simple and energy-efficient transceiver architecture.Comment: To appear in the proceedings of IEEE INFOCOM '1
Dynamic double directional propagation channel analysis with dual circular arrays
Dynamic double directional propagation channel analysis with dual circular arrays. (pp. 6 p). Peer reviewed versio
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