15 research outputs found
Performance of passive UHF RFID in cascaded correlated generalized Rician fading
Ultra high frequency radio frequency identification (UHF RFID) systems can use passive tags to reflect the signal from the reader’s transmitting antenna back to the reader’s receiving antenna for information delivery. This gives a cascaded channel that is a product of two fading components. In this work, the probability of detection, defined as the probability that the received power is above the receiver sensitivity, is derived when the two fading components suffer from correlated generalized Rician fading. This includes the Rayleigh, Rician and Nakagamim channels in the literature as special cases. Numerical results are presented to show the effects of link distances, receiver sensitivities and channel parameters on the detection probability
Performance analysis of orthogonal spacetime block codes over Nakagami-q MIMO RFID backscattering channels
The authors employ the conditional moment generating function approach to analyse the performance of orthogonal
space-time block codes over Nakagami-q (Hoyt) multiple-input multiple-output radio frequency identification backscattering
channels. New exact and asymptotic symbol error rate expressions are derived for the case of two and four receiving antennas
N = 2, 4 . The exact expressions are in the form of a sum of infinite series while the asymptotic ones are in the closed form.
The diversity order that the system can achieve is found to be L, where L is the number of tag antennas, and the performance
of this system is found to be more sensitive to the channel condition (the q parameter) of the forward link than that of the
backscattering link. The theoretical results (exact and asymptotic) are verified through comparison with simulation results
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Performance Analysis of Passive UHF RFID Systems under Cascaded Fading Channels and Interference Effects
In this paper, the performance of monostatic and
bistatic passive ultrahigh-frequency radio-frequency identification
(UHF RFID) systems under the effects of cascaded fading
channels and interference is studied. The performance metric
used is tag detection probability defined as probability that the
instantaneous received power is higher than the receiver’s sensitivity.
A closed-form expression of the detection probability is
derived using cascaded forward and backscatter fading channels
and reader antennas orientation. Furthermore, the performance
of passive RFID systems under reader-to-tag interference caused
by both the desired RFID signal and multiple RFID interferers
is analyzed, and the effect of constructive and destructive
interferences is examined. In addition, the maximum reading
range in ideal, multipath fading and interfering environments is
presented. The obtained results are very useful for the design and
optimization of passive RFID systems from RF point of view.This work was made possible by NPRP grant NPRP4-726-2-272 from
the Qatar National Research Fund (a member of Qatar Foundation).This is the accepted manuscript. The final version is available from IEEE at http://ieeexplore.ieee.org/xpl/articleDetails.jsp?reload=true&arnumber=6942226
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Detection probability of passive RFID systems under cascaded Rician and Rayleigh fading channel
Radio Frequency Identification (RFID) system uses the principle of radiative power transfer between the reader and the tag antenna. The main performance metric for RFID system is the reliable reading coverage, where the tag can be read with higher detection probability. Most of current researches consider the reader coverage to be determined only by its read range assuming monostatic configuration with omni-directional antennas. In this paper, we model and study the effect of cascaded channel fading and readers antenna orientation on the passive RFID tags, in terms of detection probability. We derive a closed-form expression for passive RFID detection probability taking into consideration the relative reader-tag antennas orientations and cascaded Rician-forward/Rayleigh-reverse fading channel. The derived formulas can be useful for design and optimization of passive RFID communication systems from RF point of view.This work was made possible by NPRP grant #NPRP4-726-2-272 from the Qatar National Research Fund (a member of Qatar Foundation).This is the accepted manuscript version. The final version is available from http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6843164. © 2014 IEE
ISI Cancellation Using Blind Equalizer Based on DBC Model for MIMO-RFID Reader Reception
Under the dyadic backscatter channel (DBC) model, a conventional zero forcing (ZF) and minimum mean square error (MMSE) method for MIMO-RFID reader reception are not able to be rapidly cancelled inter-symbol interference (ISI) because of the error of postpreamble transmission. In order to achieve the ISI cancellation, the conventional method of ZF and MMSE are proposed to resolve a convergence rate without postpreamble by using a constant modulus algorithm (CMA). Depending on the cost function, the CMA is used which based on second order statistics to estimate the channel statement of channel transfer function. Furthermore, the multiple-tag detection is also considered under the assumption of the maximum likelihood estimation. The comparison of the conventional method and the proposed method is analyzed by using computer simulation and experimental data. We can see that the proposed method is better than the conventional method with a faster ISI cancelling and a lower bit error rate (BER) improving as up to 12 tags
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Signal Processing for Wireless Power and Information Transfer
The rapid development of the Internet of Things (IoT) and wireless sensor network (WSN) technologies enable easy access and control of a variety forms of information and data from numerous number of smart devices, and give rise to many novel applications and research areas such as smart home, machine type communications, etc. However due to the small sizes, sophisticated environment, and large number of devices in network, it is hard to directly power the devices from grid. Hence the power connectivity remains one of the major issues that needs to be addressed for related IoT applications. Wireless power transfer (WPT) and backscatter communications are provisioned to be prominent solutions to overcome the power connectivity challenge, but they suer strong efficiency limitation which becomes the barrier to universally popularize such technologies. On the other hand, network optimization is also a research focus of such applications which significantly affects the performance of the system due to the high volume of connected devices and different features. In this thesis we propose advanced techniques to overcome the challenges on the low efficiency and network design of the wireless information and power transfer systems. The thesis consists of two parts. In the first part we focus on the power transmitter design which addresses the low efficiency issue associated with backscatter communication and WPT. In Chapter 2, we consider a backscatter RFID system with the multi-antenna reader and propose a blind transmit and receive adaptive beamforming algorithm. The interrogation range and data transmission performance are both investigated under such configuration. In Chapter 3 we study wireless power transfer by the beamspace large-scale MIMO system with lens antenna arrays. We first present the WPT model for the beamspace MIMO which is derived from the spatial MIMO model. By constraining on the number of RF chains in the transmitter, we formulate two WPT optimization problems: the sum power transfer problem and the max-min power transfer problem. For both problems we consider two different transmission schemes, the multi-stream and uni-stream transmissions, and we propose different algorithms to solve both problems in both schemes respectively. In the second part we study the network optimization problems in the WPT and backscatter systems. In Chapter 4, we study the resource allocation problem for a RF-powered network, where the objective is to maximize the total data throughput of all sensors. We break the problem into two subproblems: the sensor battery energy utilization problem and the charging power allocation problem of the central node, which is an RF power transmitter that transmits RF power to the sensors. We analyze and show several key properties of both problems, and then propose computationally efficient algorithms to solve both problems optimally. In Chapter 5, we study the time scheduling problem in RF-powered backscatter communication networks, where all transmitters can operates in either backscattering mode or harvest-then-transmit (HTT) mode. The objective is to decide the operating mode of each transmitter and minimize the total transmission time of the network. We also consider both ideal and realistic transmitters based on different internal power consumption models for HTT transmitters. Under both transmitter models we show several key properties, and propose bisection based algorithms which has low computational complexity that solves the problem optimally. The results are then extended to the massive MIMO regime