Search

A 3-D reference model for wideband multiple-input multiple-output (MIMO) mobile-to-mobile (M-to-M) channels is reviewed along with its corresponding first- and second-order channel statistics. To validate the reference model, an experimental MIMO M-to-M channel-sounding campaign was conducted for M-to-M vehicular communication with vehicles that travel along surface streets and expressways in a metropolitan area. To compare the first- and second-order channel statistics that were obtained from the reference model with those obtained from the empirical measurements, a new maximum-likelihood-based stochastic estimator is derived to extract the relevant model parameters from the measured data. The measured data is processed and compared with the analytical results. The close agreement between the analytically and empirically obtained channel statistics confirms the utility of the proposed reference model and the method for estimating the model parameters. Index Terms--Channel sounding, mobile-to-mobile (M-to-M) channels, parameter estimation, wideband channel model.

A 3-D reference model is proposed for multipleinput multiple-output (MIMO) mobile-to-mobile (M-to-M) multipath-fading channels. From this model, a closed-form joint space--time correlation function is derived for a 3-D nonisotropic scattering environment. Two sum-of-sinusoids-based 3-D simulation models for MIMO M-to-M multipath-fading channels are proposed. The statistics of the simulation models are verified by simulation. Finally, these simulation models are used to evaluate the effect of the space--time correlation on the outage capacity of uniform linear antenna arrays and to compare the capacities of linear, circular, and spherical antenna arrays. Index Terms--Antenna arrays, capacity analysis, mobile-tomobile (M-to-M) channels, sum-of-sinusoids (SoS)-based channel simulators, 3-D scattering environment.

A single- and double-bounced two-ring parametric reference model is proposed for multiple-input multiple-output (MIMO) mobile-to-mobile (M-to-M) Ricean fading channels. From this model, a closed-form joint space-time correlation function and a space-Doppler power spectrum are derived for a two-dimensional (2-D) non-isotropic scattering environment. Also, space-time correlation functions for the in-phase and quadrature components of the complex faded envelope are derived, assuming a 2-D isotropic scattering environment. Finally, two new sum-of-sinusoids based simulation models for MIMO M-to-M Ricean fading channels are proposed. The statistics of the simulation models are verified by simulation. The results show that the simulation models are a good approximation of the reference model and that they outperform existing simulation models. Index Terms--Deterministic and statistical methods, Doppler spectrum, fading channel simulator, mobile-to-mobile channels, Ricean and Rayleigh fading, sum-of-sinusoids.

Recently, low-reflection low-pass RLC filters with a linear phase characteristic have been reported. This paper is an extension of this study on bandpass filters, including their realizations with lumped-element and distributed-parameter networks. A topology particularly suitable for microstrip techniques is proposed. It yields a compact design that enables miniaturization and is easy for manufacturing and tuning. Index Terms--Bandpass filters, impedance matching, linear phase filters.

Gaussian-like filters are frequently used in digital signal transmission. Usually, these filters are made of lumped inductors and capacitors. In the stopband, these filters exhibit a high reflection, which can create unwanted signal interference. To prevent that, a new low-reflection ladder network is introduced that consist of resistors, inductors, and capacitors. The network models fictitious transmission lines with Gaussian-like amplitude characteristics. Starting from the analysis of this network, a procedure is developed for synthesis of a new class of lumped-element RLC filters. These filters have transmission coefficients similar to the classical Bessel filters. In contrast to the Bessel filters, the new filters exhibit a low reflection both in the stopband and passband, they have a small span of element parameters, and they are easy for manufacturing and tuning. Index Terms--Distributed parameter filters, impedance matching, linear phase filters, low-pass filters.

We consider uniform lossy transmission lines characterized by their primary parameters. Exact and approximate formulas for the characteristic impedance and propagation coefficient are reviewed and discussed for low-loss lines. Approximating the characteristic impedance by its real part can lead to erroneous results for the input impedance of short-and open-circuited stubs. This problem is analytically demonstrated on electrically short stubs. Results obtained using the exact and approximate expressions are compared with numerical solutions that are generated by various circuit simulation software. Index Terms--Circuit simulation, distributed parameter circuits, lossy circuits, modeling, simulation software, transmission-line theory.

Recent proliferation of CPS and IoT devices has led to an increasing demand for analyzing performance and timing of event-driven computational activity, especially interrupts and exceptions. However, these devices typically lack hardware resources, power, and system-software infrastructure for profiling/monitoring such events. Even when feasible, the profiling/monitoring activity itself can perturb the performance and timing of the timing-sensitive activity to be analyzed, therefore producing misleading results. Thus, we present Primer, a novel approach for profiling interrupts. Primer leverages existing unintentional (side-channel) electromagnetic emanations of the profiled/monitored device to identify its asynchronous execution (e.g., interrupt handlers). Primer leaves the monitored system (and its behavior) completely unchanged, requires no system resources or support, and introduces neither overheads nor perturbation in the monitored system. We validate Primer by analyzing signals that correspond to five different types of interrupts on an IoT device (ARM Cortex-M), achieving 99.5% accuracy (with no false positives), and on an MSP430 microcontroller-based device with even better accuracy. We also demonstrate the effectiveness of Primer in analyzing page faults and network interrupts when executing real-world applications on a more sophisticated embedded device (ARM Cortex-A8), and show that the results provided by Primer can provide useful insights about an application's interaction with the system's virtual memory and network-oriented services. [ABSTRACT FROM AUTHOR]