This paper proposes a novel signal processing technique that doubles the range resolution of FMCW~(Frequency Modulated Continuous Wave) sensing without increasing the required bandwidth. The proposed design overcomes the resolution limit imposed by bandwidth by exploiting the phase consistency observed in the special frequency variation of the beat signal derived from triangle FMCW. Through this approach, the resolution is doubled while maintaining high spectrum SNR. A system model for signal processing is presented, and the energy distribution of the derived beat spectrum is analyzed. The effectiveness of the proposed technique is validated through model-based simulations.
Ben A. P. Nel, Anja K. Skrivervik, Mats Gustafsson
This paper presents radiation efficiency and gain bounds for microstrip patch antennas. The presented bounds are shown to be good predictors of antenna performance. Using the bounds, patch miniaturization techniques based on high permittivity substrates and geometrical shaping are compared. Further, a semi-analytic model is developed to approximate the bounds. Measurements are used to validate the bounds. Finally, maximum bandwidth of a microstrip patch antenna is linked to its maximum radiation efficiency.
Sergio Hernandez F., Christophe Peucheret, Francesco Da Ros
et al.
The rate and reach of directly-modulated laser links is often limited by the interplay between chirp and fiber chromatic dispersion. We address this by optimizing the transmitter, receiver, bias and peak-to-peak current to the laser jointly. Our approach outperforms Volterra post-equalization at various symbol rates.
Luisa Watkins, Pietro Stinco, Alessandra Tesei
et al.
We introduce a Bayesian estimation approach for the passive localization of an acoustic source in shallow water using a single mobile receiver. The proposed probabilistic focalization method estimates the time-varying source location in the presence of measurement-origin uncertainty. In particular, probabilistic data association is performed to match time-differences-of-arrival (TDOA) observations extracted from the acoustic signal to TDOAs predictions provided by the statistical model. The performance of our approach is evaluated using real acoustic data recorded by a single mobile receiver.
Henrique Buglia, Eric Sillekens, Lidia Galdino
et al.
Per-channel launch power optimisation in a hybrid-amplified link with optimised pump powers and wavelengths is described. Compared to using the optimum spectrally uniform launch power, an average SNR gain of 0.13 dB is obtained against 0.56 dB for the same system operating with lumped amplifiers only.
Shantia Yarahmadian, Maryam Rahmani, Michael Mazzola
In this paper, we introduce a novel waveletbased algorithm for reconstructing time-domain impulse responses from band-limited scattering parameters (frequencydomain data) with a particular focus on ship hull applications. We establish the algorithm and demonstrate its convergence, as well as its efficiency for a class of functions that can be expanded as exponential functions. We provide simulation results to validate our numerical results.
In this letter, based on the variational model, we propose a novel time-frequency post-processing technique to approximate the ideal time-frequency representation. Our method has the advantage of modularity, enabling "plug and play", independent of the performance of specific time-frequency analysis tool. Therefore, it can be easily generalized to the fractional Fourier domain and the linear canonical domain. Additionally, high-resolution is its merit, which depends on the specific instantaneous frequency estimation method. We reveal the relationship between instantaneous frequency estimation and reassignment method. The effectiveness of the proposed method is verified on both synthetic signals and real world signal.
Macroscopic diversity in radiomobile systems is a technique in which the terminal is in parallel connection with two base stations. It is a fundamental element in the operation of third generation mobile networks using CDMA. (IS 95, UMTS, etc.). A representation of the propagation phenomena involved requires joint modeling of the two transmission channels. The article presents a very simple method for simultaneously measuring their impulse responses, developed for this purpose. This method was the subject of a patent. It can more generally be applied to any number of channels and should allow the reuse of already existing single-channel sounders.
Nasrin Razmi, Bho Matthiesen, Armin Dekorsy
et al.
Distributed training of machine learning models directly on satellites in low Earth orbit (LEO) is considered. Based on a federated learning (FL) algorithm specifically targeted at the unique challenges of the satellite scenario, we design a scheduler that exploits the predictability of visiting times between ground stations (GS) and satellites to reduce model staleness. Numerical experiments show that this can improve the convergence speed by a factor three.
With the advancement of sensing technologies over the years, it has become critical to ensure the seamless connectivity of the Internet of Things (IoT) gadgets. With the advancement of communication technology, cellular networks are increasingly being utilized to link IoT systems. An IRS is a rectangular metasurface made up of a vast number of reflecting components that has recently gained research attention due to its ability to significantly improve the energy and spectral efficiencies of communication networks by modifying wireless transmission environments.
We design and implement an adaptive machine learning equalizer that alternates multiple linear and nonlinear computational layers on an FPGA. On-chip training via gradient backpropagation is shown to allow for real-time adaptation to time-varying channel impairments.
This work considers uncertainty relations on time frequency distributions from a signal processing viewpoint. An uncertainty relation on the marginalizable time frequency distributions is given. A result from quantum mechanics is used on Wigner distributions and marginalizable time frequency distributions to investigate the change in variance of time and frequency variables from a signal processing perspective. Moreover, operations on signals which leave uncertainty relations unchanged are studied.
The paper introduces a new lossless, highly robust compression algorithm that similar with LZW algorithm, yet the algorithm discards dictionary processing and uses irregular sequences with massive, random information instead. Then the paper found the ineffectiveness of the algorithm due to limited computing ability of hardware and made a few improvements to the algorithm. The algorithm is recommended to be applied in interplanetary communications between a high-compute-ability device and a low-compute-ability receiving device, whose signal would be easily interfered by cosmos rays.
This paper analyzes the smart charging system for dealing with issues related to large parking garages, and analyzes the relevant technical standards of intelligent charging piles application and comprehensive transportation hubs. It mainly includes the number, area and charging method of the charging piles installed in the garages. New forms of construction management is conceived, and the investment and construction are reinforced, apportioning all charging system property rights to investment parties. Simultaneously, the investors take full responsibility for the future management and operation, mainly including the collection of service fees and charging fees.
The faster-than-Nyquist nonlinear frequency division multiplexing system was first proposed, which provided 12.5% and 25% increase in spectral efficiency for the compression factor of 0.89 and 0.8 respectively.
Model based signal processing or signal analysis or signal representation has a rather different point of view from the more traditional filtering and algorithm based approaches. However, in all of these, the names of Prony, Padé, and linear prediction come up. This note examines these ideas with the goal of showing they are all based on the same principles and all can be extended and generalized. A particular application is the frequency sampling design of IIR digital filters.
We present how to implement fiber-distributed signal processing in the context of fiber-wireless communications by using different multicore fibers, providing both radio access distribution and microwave photonics signal processing in the same fiber medium.
This paper considers a hybrid approach to joint estimation of channel information and antenna impedance, for single-input, single-output channels. Based on observation of training sequences via synchronously switched load at the receiver, we derive joint maximum a posteriori and maximum-likelihood (MAP/ML) estimators for channel and impedance over multiple packets. We investigate important properties of these estimators, e.g., bias and efficiency. We also explore the performance of these estimators through numerical examples.