Canonical coordinates for transform coding of noisy sources

This paper investigates the secure communication in reconfigurable intelligent surface aided cell-free massive MIMO system in the presence of active eavesdropping, where the access points (APs) are equipped with low resolution analogto-digital/digital-to-analog converters (ADCs/DACs). Specifically, the additive quantization noise model (AQNM) is explored to capture the impacts of coarse ADCs/DACs. To reduce the channel estimation overhead, all APs employ a minimum mean-squared-error channel estimator which estimates the aggregated channel including both the direct and indirect channels. With the available imperfect channel state information (CSI), conjugate beamforming and random beamforming are applied at the APs and the RISs for downlink data transmission. Moreover, the closed-form expression of the achievable ergodic secrecy rate is derived which can be used to evaluate the impact of the number of the APs, the number of the RISs and the ADCs/DACs resolution on the systems performance. Finally, numerical and simulation results are presented to verify the analytical results.

A generalized uplink cell-free massive multi-input multi-output (MIMO) system assuming access points (APs) are paired with mixed-resolution analog-to-digital converters (ADCs) and digital-to-analog converters (DACs) is investigated in this article. Specifically, the mixed-ADC/DAC architecture sacrifices part of performance gains and advocates a few low-precision ADCs/DACs to reduce the power consumption. Based on this antenna structure, we derive closed-form achievable rate expressions for maximal ratio combining (MRC) receiver filters by drawing support from the additive quantization noise model (AQNM) and analyze the impacts of the key design parameters, i.e., the number of total antenna arrays, the precision of coarse ADCs/DACs, the proportion of ideal ADCs/DACs in the mixed ADCs/DACs structure, and the power control strategy. In addition, the energy efficiency (EE) of the considered mixed-ADC/DAC architecture is also explored by recalling a generic power consumption model. Aside from this, to guarantee uniformly good service wherever users are geographically located, a max–min fairness power optimization algorithm is proposed, which can be determined by solving a geometric programming problem. Numerical simulations validate our theoretical analyses and examine the effectiveness of the proposed algorithm.

The practical application for massive MIMO relaying system with a large number of antennas is considered a challenging problem. To solve this problem, a promising solution is to utilize double precision analog-to-digital converter (ADC) and digital-to-analog converter (DAC) at the relay. Depending on the additive quantization noise model, closed-form expression for system sum rate is analyzed. Furthermore, some asymptotic simplifications are utilized to reveal the effects of some parameters on the system performance. These parameters such as the proportion of full precision in the double precision architecture (κ), the number of quantization bits (b) and the number of relay antennas (N). In addition, a tradeoff between system sum rate and power consuming is discussed by deriving energy efficiency (EE). Moreover, the tradeoff between EE and the system sum rate is investigated with different numbers of full precision ADCs/DACs. Simulation results demonstrated that large antenna array with double precision ADCs/DACs can reduce hardware cost and power consuming for practical massive MIMO relaying systems.

We present an automated method to track and identify neurons in C. elegans, called "fast Deep Learning Correspondence" or fDLC, based on the transformer network architecture. The model is trained once on empirically derived synthetic data and then predicts neural correspondence across held-out real animals via transfer learning. The same pre-trained model both tracks neurons across time and identifies corresponding neurons across individuals. Performance is evaluated against hand-annotated datasets, including NeuroPAL [1]. Using only position information, the method achieves 80.0% accuracy at tracking neurons within an individual and 65.8% accuracy at identifying neurons across individuals. Accuracy is even higher on a published dataset [2]. Accuracy reaches 76.5% when using color information from NeuroPAL. Unlike previous methods, fDLC does not require straightening or transforming the animal into a canonical coordinate system. The method is fast and predicts correspondence in 10 ms making it suitable for future real-time applications.

We give a detailed account of an ab initio spectral approach for the calculation of energy spectra of two active electron atoms in a system of hyperspherical coordinates. In this system of coordinates, the Hamiltonian has the same structure as the one of atomic hydrogen with the Coulomb potential expressed in terms of a hyperradius and the nuclear charge replaced by an angle dependent effective charge. The simplest spectral approach consists in expanding the hyperangular wave function in a basis of hyperspherical harmonics. This expansion however, is known to be very slowly converging. Instead, we introduce new hyperangular Sturmian functions. These functions do not have an analytical expression but they treat the first term of the multipole expansion of the electron–electron interaction potential, namely the radial electron correlation, exactly. The properties of these new functions are discussed in detail. For the basis functions of the hyperradius, several choices are possible. In the present case, we use Coulomb–Sturmian functions of half integer angular momentum. We show that, in the case of H−, the accuracy of the energy and the width of the resonance states obtained through a single diagonalization of the Hamiltonian, is comparable to the values given by state-of-the-art methods while using a much smaller basis set. In addition, we show that precise values of the electric-dipole oscillator strengths for transitions in helium are obtained thereby confirming the accuracy of the bound state wave functions generated with the present method.

The additive white Gaussian noise (AWGN) model is commonly used in the development of communication systems, and adequately models many noisy environments. However the impulsive noise from snapping shrimp is poorly approximated by this model. The mismatch in model has an adverse impact on the performance of conventional communication systems operating in warm shallow waters. The AWGN model may be replaced by the more general additive white symmetric α-stable noise (AWSαSN) model, which better approximates the heavy tailed noise due to snapping shrimp. When converted to the complex baseband representation, the resulting noise for the AWSαSN case is radically different from its Gaussian counterpart. In this talk some properties of baseband noise for the general AWSαSN case are investigated. These properties can be used to guide design decisions for coherent communication systems operating in warm shallow waters. The baseband noise is generally not isotropic and furthermore the real and imaginary components may be dependent. By varying certain physical parameters different non-isotropic distributions may be attained. The resulting properties can be exploited to design communication systems that are able to provide robust performance in the presence of snapping shrimp noise.

Smoothness priors transfer function estimation

In this paper, we study the achievable rate and the energy efficiency of analog, hybrid, and digital combining (AC, HC, and DC) for millimeter wave (mmW) receivers. We take into account the power consumption of all receiver components, not just analog-to-digital converters (ADCs), determine some practical limitations of beamforming in each architecture, and develop performance analysis charts that enable comparison of different receivers simultaneously in terms of two metrics, namely, spectral efficiency (SE) and energy efficiency (EE). We present a multi-objective utility optimization interpretation to find the best SE-EE weighted tradeoff among AC, DC, and HC schemes. We consider an additive quantization noise model to evaluate the achievable rates with low resolution ADCs. Our analysis shows that AC is only advantageous if the channel rank is strictly one, the link has very low SNR, or there is a very stringent low power constraint at the receiver. Otherwise, we show that the usual claim that DC requires the highest power is not universally valid. Rather, either DC or HC alternatively results in the better SE versus EE tradeoff depending strongly on the considered power consumption characteristic values for each component of the mmW receiver.

This chapter focuses on analysis of the coordinate system accuracy. It is assumed that the essence of a model of such a measuring system is that component errors overlap each other, determining the error vector for every point in the measuring volume. The description of sources of kinematic errors is presented as other methods for their identification with the use of plate standards, laser interferometers, or laser tracers together with the software description. The original matrix method (MM) for coordinate system error identification is described together with the connection of this MM method with the reproducibility error of the measuring point (REMP). Examples of research results are also presented in Annexes B, C, and D. The chapter mainly focuses on the issue of measuring tip contact with the measured object, and it is based on the author’s original method for the identification of a probing system: contact probe errors with the use of a circular standard together with the system of software separation of components. The method of software correction of CMS accuracy is also presented. This method is based on determination of correction matrix components as a basis for software correction of errors of modern coordinate systems. Moreover, this chapter describes the basis for construction of virtual coordinate systems, including a system of articulated arm-coordinate measuring machine that uses Denavit–Hartenberg notation.

Detecting and correcting a difference of coordinate system definition among a team of robot is mandatory when robots operate in the same environment. In this paper we develop a system for sharing a common coordinate system. Comparing measuring results of same environment among multiple robots, it is possible to detect coordinate system error. We considered this approach and implemented a programming framework which shares a common coordinate system. This approach does not require any information about the environment in advance. Utilizing ultrasonic range finder with a flat wall detection algorithm is possible to implement the proposed framework. The implementation constraints the presence of a flat wall as a part of the environment in order to calculate the difference of coordinate system, already defined among the robots. Then it automatically corrects the difference of the definition of coordinate systems. The experimental result shows its functionality.

It is proved that if an anisotropic medium has an open set of singular directions, then this medium has two slowness surfaces that completely coincide. The coinciding slowness surfaces form one double singular slowness surface. The corresponding anisotropic medium is an elliptical orthorhombic (ORT) medium with equal stiffness coefficients c44=c55=c66 rotated to an arbitrary coordinate system. Based on the representation of the Christoffel matrix as a uniaxial tensor and considering that the elements of the Christoffel matrix are quadratic forms in the components of the slowness vector, a system of homogeneous polynomial equations was derived. Then, the identical equalities between homogeneous polynomials are replaced by the equalities between their coefficients. As a result, a new system of equations is obtained, the solution of which is the values of the reduced (density normalized) stiffness coefficients in a medium with a singular surface. Conditions for the positive definite of the obtained stiffness matrix are studied. For the defined medium, the Christoffel equations and equations of group velocity surfaces are derived. The orthogonal rotation matrix that transforms the medium with a singular surface into an elliptic ORT medium in the canonical coordinate system is determined. In the canonical coordinate system, the slowness surfaces S1 and S2 waves coincide and are given by a sphere with a radius . The slowness surface of qP waves in the canonical coordinate system is an ellipsoid with semi-axes , , . The polarization vectors of S1 and S2 waves can be arbitrarily selected in the plane orthogonal to the polarization vector of the qP wave. However, the qP wave polarization vector can be significantly different from the wave vector. This feature should be taken into account in the joint processing and modelling of S and qP waves. The results are illustrated in one example of an elliptical ORT medium.

In this paper, we derive the achievable rate of single-carrier frequency domain equalizer (SC-FDE) and orthogonal frequency division multiplexing (OFDM) systems, constrained on low resolution analog to digital converters (ADCs). We assume that there is a full knowledge of channels at both transmitter and receiver sides. We model low resolution ADCs with an additive uniform quantization noise. We consider an ultra-wide band millimeter wave (mm-Wave) system with a frequency selective channel. The channel is based on practical results at mm-Wave frequencies. Our numerical results show that SC-FDE systems with minimum mean square error (MMSE) equalizers outperform OFDM and SC-FDE systems with zero forcing (ZF) equalizers at high signal to noise ratio (SNR) regimes. Moreover, benefits of increasing the ADCs resolution are not significant due to exponentially increment in the power consumption of ADCs.

The use of steganography and watermarking techniques for a secure identification and automatic authentication of the holder’s photo in an ICAO-consistent (travel) document is proposed. A specific distortion of the hidden watermarks is caused by the print-scan process, as a printed photo is scanned to constitute the reference pattern in face verification. The main distortions induced by this process are identified - image rotation and cropping, nonlinear intensity change and additive color quantization noise. Three steganography methods are selected and adapted for this application. They provide hidden watermark insertion in the image domain, the Fourier-Mellin transform domain or in a net of normalized triangle regions. Test results induce the conditions for the proper use of these methods.

The capacity limits of fiber-optic communication systems in the nonlinear regime are not yet well understood. In this paper, we study the capacity of amplitude modulated first-order soliton transmission, defined as the maximum of the so-called time-scaled mutual information. Such definition allows us to directly incorporate the dependence of soliton pulse width to its amplitude into capacity formulation. The commonly used memoryless channel model based on noncentral chi-squared distribution is initially considered. Applying a variance normalizing transform, this channel is approximated by a unit-variance additive white Gaussian noise (AWGN) model. Based on a numerical capacity analysis of the approximated AWGN channel, a general form of capacity-approaching input distributions is determined. These optimal distributions are discrete comprising a mass point at zero (off symbol) and a finite number of mass points almost uniformly distributed away from zero. Using this general form of input distributions, a novel closed-form approximation of the capacity is determined showing a good match to numerical results. Finally, mismatch capacity bounds are developed based on split-step simulations of the nonlinear Schrdinger equation considering both single soliton and soliton sequence transmissions. This relaxes the initial assumption of memoryless channel to show the impact of both inter-soliton interaction and Gordon–Haus effects. Our results show that the inter-soliton interaction effect becomes increasingly significant at higher soliton amplitudes and would be the dominant impairment compared to the timing jitter induced by the Gordon–Haus effect.

Localization of sensor node is imperative in Wireless Sensor Networks (WSN) as data gathered at the user end become meaningless without location information of the node. In this work, impact of anchor position errors on WSN localization using Mobile Anchor Positioning (MAP) Algorithm has been investigated by evaluating two deployment strategies. In deployment I sensor nodes are randomly spread in the entire chosen area (1000 χ 1000) whilst deployment II has nodes spread in the central region of the chosen area. Firstly, MAP Algorithm employing three anchor nodes is investigated for the two deployments. To study the impact of mobile anchors on MAP, anchor number is increased to four and the two deployments are investigated again. Further, this work also investigates the effect of anchor position errors on localization accuracy of sensor nodes. Error term is modelled using Additive White Gaussian Noise (AWGN) Model. Performance metrices considered for validation are Average Root Mean Square Error and Execution time.