88 research outputs found
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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
On the Effect of Correlation on the Capacity of Backscatter Communication Systems
We analyse the effect of correlation between the forward and backward links
on the capacity of backscatter communication systems. To that aim, we obtain an
analytical expression for the average capacity under a correlated Rayleigh
product fading channel, as well as closed-form asymptotic expressions for the
high and low signal-to-noise ratio (SNR) regimes. Our results show that
correlation is indeed detrimental for a fixed target SNR; contrarily to the
common belief, we also see that correlation can be actually beneficial in some
instances when a fixed power budget is considered.Comment: This work has been submitted for publication. Copyright may be
transferred without notice, after which this version may no longer be
accessibl
Sum Throughput Maximization in Multi-Tag Backscattering to Multiantenna Reader
Backscatter communication (BSC) is being realized as the core technology for
pervasive sustainable Internet-of-Things applications. However, owing to the
resource-limitations of passive tags, the efficient usage of multiple antennas
at the reader is essential for both downlink excitation and uplink detection.
This work targets at maximizing the achievable sum-backscattered-throughput by
jointly optimizing the transceiver (TRX) design at the reader and
backscattering coefficients (BC) at the tags. Since, this joint problem is
nonconvex, we first present individually-optimal designs for the TRX and BC. We
show that with precoder and {combiner} designs at the reader respectively
targeting downlink energy beamforming and uplink Wiener filtering operations,
the BC optimization at tags can be reduced to a binary power control problem.
Next, the asymptotically-optimal joint-TRX-BC designs are proposed for both low
and high signal-to-noise-ratio regimes. Based on these developments, an
iterative low-complexity algorithm is proposed to yield an efficient
jointly-suboptimal design. Thereafter, we discuss the practical utility of the
proposed designs to other application settings like wireless powered
communication networks and BSC with imperfect channel state information.
Lastly, selected numerical results, validating the analysis and shedding novel
insights, demonstrate that the proposed designs can yield significant
enhancement in the sum-backscattered throughput over existing benchmarks.Comment: 17 pages, 5 figures, accepted for publication in IEEE Transactions on
Communication
Impacts of Scene Geometry and Vehicle Speed on the Performance of RFID based AVI/ETC System
Passive UHF Radio Frequency Identification (RFID) is a potential technology for Automatic Vehicle Identification (AVI) and Electronic Toll Collection (ETC) systems. However, the identification performance is often seriously influenced by the RF radiation zone and anti-collision protocol simultaneously. The impacts of scene geometry and vehicle speed on the identification rate are analyzed and modeled for a typical AVI/ETC application scenario. A calculation method of identification zone is firstly proposed based on the ray-tracing theory. Then the communication procedure is divided into three processes, which are also modeled using individual probability methods. Numerical simulations show that there are strong influences on the tag identification rate caused by the tag speed and antenna inclination angles, and we can obtain a higher identification rate through optimizing them
A Tractable Line-of-Sight Product Channel Model: Application to Wireless Powered Communications
We here present a general and tractable fading model for line-of-sight (LOS) scenarios, which is based on the product of two independent and non-identically distributed κ- μ shadowed random variables. Simple closed-form expressions for the probability density function and cumulative distribution function are derived, which are as tractable as the corresponding expressions derived from a product of Nakagami-m random variables. This newly proposed model simplifies the challenging characterization of LOS product channels, as well as combinations of LOS channels with non-LOS ones. Results are used to analyze performance measures of interest in the context of wireless powered communications.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
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