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Digital predistortion (DPD) is an effective power amplifier (PA) linearization technique improving the system energy efficiency. At this point, real-time DPD adaptation is still an open issue due to the high computational complexity during the coefficients estimation procedure. Online censoring approach, which is effective in reducing the redundant data samples, can be applied in the DPD coefficients...
Signal processing on graphs becomes popular nowadays due to its great potential in processing the large amount of high dimensional data which exhibit irregular structures. As a signal propagates on a graph, the signal at a later time slot can be thought of as the graph-filtered version of the previous one. Therefore, estimation of the graph filter is important and serves as the building block for...
Unlike the time-division duplexing (TDD) systems, the downlink (DL) and uplink (UL) channels are not reciprocal anymore in the case of frequency-division duplexing (FDD). However, some long-term parameters, e.g. the time delays and angles of arrival (AoAs) of the channel paths, still enjoy reciprocity. In this paper, by efficiently exploiting the aforementioned limited reciprocity, we address the...
In frequency-division duplexing (FDD) massive multiple-input multiple-output (MIMO) systems, the downlink (DL) and uplink (UL) channels are not reciprocal anymore. However, some long-term parameters, e.g. the time delays and angles of arrival (AoAs) of the channel paths, still enjoy reciprocity. In this paper, through efficiently exploiting the aforementioned limited reciprocity, we address the DL...
As more than 2.5 quintillion bytes of data are generated every day, the era of big data is undoubtedly upon us. Running analysis on extensive datasets is a challenge. Fortunately, a significant percentage of the data accrued can be omitted while maintaining a certain quality of statistical inference in many cases. Censoring provides us a natural option for data reduction. However, the data chosen...
The technical state evaluation of Vehicle Equipment is a necessary step to operate and support. Considered conditions such as technical characters, operate environments and support elements, this paperresearches its technical state cluster, which is based on BIC(Schwarz's Bayesian Criterion). The conclusion reveals that BIC is accurate and concise to cluster the technical state of vehicle equipment.
In this paper, we look into the issue of intra-cell uplink (UL) pilot orthogonalization and schemes for mitigating the inter-cell pilot contamination with a realistic massive multi-input multi-output (MIMO) orthogonal frequency-division multiplexing (OFDM) system model. First, we show how to align the power-delay profiles (PDP) of different users served by one BS so that the pilots sent within one...
In PET detector designs, high sensitivity is a critical performance parameter required for obtaining images with reasonable signal-to-noise ratio (SNR). The sensitivity of a PET scanner is primarily determined by the efficiency of detection system (e.g. crystal thickness and solid angle coverage), but could be enhanced by distinguishing and recovering inter-crystal Compton scattering events while...
Attenuation correction is critical to accurate PET quantitation. Accurate and robust attenuation correction remains challenging in hybrid PET/MR because it is difficult to segment bones, internal air and lungs accurately in MR images and MR often suffers from artifacts due to metal implants and signal shading. Joint estimation (JE) of activity and attenuation from time-of-flight (TOF) PET data has...
We derived a system of two-dimensional equations for thickness-extensional vibrations of a four-layered plate consisting of a piezoelectric thin film on an elastic substrate with driving and ground electrodes. It takes into consideration the couplings among the thickness-extensional mode to extensional, flexural, fundamental and second-order thickness-shear modes. Mindlin's approach of using a power...
Thickness-extensional vibration of a rectangular piezoelectric thin film filter symmetrically covered with two driving electrodes was studied in this paper. The Tiersten and Stevens scalar equation was employed. The Ritz method based on the variational formulation constructed in our previous work was used with trigonometric series as basis functions. Free vibration modes and corresponding resonant...
This paper demonstrates a stress function based approach for predicting the static stresses in piezoelectric composite laminates under piezoelectric excitation. The stress function based approach is quite different from the traditional plate and shell theories that adopt the displacement functions as initial assumptions, where the stress boundary conditions are prescribed at the surfaces and applied...
A numerical approach to calculate multivariate transcendental equations in complex number domain that can be applied to solve dispersion equation is presented here. The mathematical derivations of the convergence of the moduli of the equations around null point are presented strictly, when the transcendental equation is univariate. Similar process also applies to the case when the equations are multivariate...
Dual-band and multi-band power amplifiers (PAs) becomes popular as they can effectively reduce the equipment cost and operation cost. On the other hand, the nonlinear interference among signals in different bands needs special attention. Previous modeling results [1] suffer performance degradation when the intermodulation terms among bands fall into bands of the signals. In this paper, we start from...
In a visible light communication (VLC) system, the light emitting diode (LED) is nonlinear for large signals, which limits the transmission power, or equivalently the coverage of the VLC system. When the input signal amplitude is large, the nonlinear distortion creates both harmonics and intermodulation distortions, which degrades the transmission error vector magnitude (EVM). To evaluate the impact...
In the cooperative relay system which employs link adaptation, the modulation of relay link is probably different from that of source link. The conventional intra-symbol bit rearrangement scheme in the current specifications can only achieve a limited performance gain in this scenario. This paper proposed an inter-symbol bit rearrangement scheme which is based on the minimum Euclidean distance. The...
This paper analyses free vibration frequencies and modes for thickness-shear and thickness-twist vibrations of centrally partially electroded circular AT-cut quartz plate by using 3-D finite element models of commercial package ANSYS. The analysis has been done with the 3-D Finite Element Analysis (FEA) for displacements and vibration frequency at the thickness-shear mode, which is important in the...
A theoretical analysis on a rectangular energy-trapped piezoelectric thin zinc oxide film resonator operating with thickness-extensional modes is performed in this paper. The two-dimensional scalar differential equations derived by Tiersten and Stevens are used which can describe the in-plane mode distribution. Based on the scalar equations, we construct a variational formulation which provides a...
In this paper, the piezoelectric film, electrodes and the silicon substrate of FBARs are modeled as a layered sandwich structure for studying the wave propagation in it. The harmonic solutions should satisfy the governing equations of each layer. Then, the dispersion relations can be obtained by the continuity conditions and boundary conditions. The dispersion curves are compared with the results...
In modern wireless communication systems, the adaptive digital predistortion (DPD) is widely used to compensate for the nonlinearity in the radio front-end. In the DPD implementation, the conventional coefficient estimation algorithm is computationally intensive and prevents the application of complex DPD models. In [1], we have derived an efficient coefficients estimation algorithm based on orthonormal...
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