arXiv subjects

Hassan Aghaeinia

Publications and source records attributed to Hassan Aghaeinia.

7 recordsLinked to original sources

arXiv2024

Enhanced Depth Estimation and 3D Geometry Reconstruction using Bayesian Helmholtz Stereopsis with Belief Propagation

Helmholtz stereopsis is one the versatile techniques for 3D geometry reconstruction from 2D images of objects with unknown and arbitrary reflectance surfaces. HS eliminates the need for surface reflectance, a challenging parameter to measure, based on the Helmholtz reciprocity principle. Its Bayesian formulation using maximum a posteriori (MAP) probability approach has significantly improved reconstruction accuracy of HS method. This framework enables the inclusion of smoothness priors which enforces observations and neighborhood information in the formulation. We used Markov Random Fields (MRF) which is a powerful tool to integrate diverse prior contextual information and solved the MAP-MRF using belief propagation algorithm. We propose a new smoothness function utilizing the normal field integration method for refined depth estimation within the Bayesian framework. Utilizing three pairs of images with different viewpoints, our approach demonstrates superior depth label accuracy compared to conventional Bayesian methods. Experimental results indicate that our proposed method yields a better depth map with reduced RMS error, showcasing its efficacy in improving depth estimation within Helmholtz stereopsis.

eess.IV↗

arXiv2019

Wi2Vi: Generating Video Frames from WiFi CSI Samples

Objects in an environment affect electromagnetic waves. While this effect varies across frequencies, there exists a correlation between them, and a model with enough capacity can capture this correlation between the measurements in different frequencies. In this paper, we propose the Wi2Vi model for associating variations in the WiFi channel state information with video frames. The proposed Wi2Vi system can generate video frames entirely using CSI measurements. The produced video frames by the Wi2Vi provide auxiliary information to the conventional surveillance system in critical circumstances. Our implementation of the Wi2Vi system confirms the feasibility of constructing a system capable of deriving the correlations between measurements in different frequency spectrums.

cs.CV↗

arXiv2018

Maximizing First Order Approximate Mean of SINR under Imperfect Channel State Information for Throughput Enhancement of MIMO Interference Networks

In this research paper approximate mean of signal-to-interference-plus-noise ratio (SINR) under imperfect channel state information (CSI) is computed and maximized for throughput enhancement of MIMO interference networks. Each transmitter and receiver has respectively M and N antennas and network operates in a time division duplex mode. Each transceiver adjusts its filter to maximize the expected value of SINR. The proposed New Approach for Throughput Enhancement under imperfect CSI utilizes the reciprocity of wireless networks to maximize the estimated mean. The sum rate performance of the proposed algorithm is verified using Monte Carlo simulations.

cs.IT↗

arXiv2018

Robust Transceiver Design for Reciprocal M*N Interference Channel Based on Statistical Linearization Approximation

This paper focuses on robust transceiver design for throughput enhancement on the interference channel (IC), under imperfect channel state information (CSI). In this paper, two algorithms are proposed to improve the throughput of the multi-input multi-output (MIMO) IC. Each transmitter and receiver has respectively M and N antennas and IC operates in a time division duplex mode. In the first proposed algorithm, each transceiver adjusts its filter to maximize the expected value of signal-to-interference-plus-noise ratio (SINR). On the other hand, the second algorithm tries to minimize the variances of the SINRs to hedge against the variability due to CSI error. Taylor expansion is exploited to approximate the effect of CSI imperfection on mean and variance. The proposed robust algorithms utilize the reciprocity of wireless networks to optimize the estimated statistical properties in two different working modes. Monte Carlo simulations are employed to investigate sum rate performance of the proposed algorithms and the advantage of incorporating variation minimization into the transceiver design.

cs.IT↗

arXiv2014

Fast and Optimal Power Control Games in Multiuser MIMO Networks

In this paper, we analyze the problem of power control in a multiuser MIMO network, where the optimal linear precoder is employed in each user to achieve maximum point- to-point information rate. We design a distributed power control algorithm based on the concept of game theory and contractive functions that has a couple of advantages over the previous designs (e.g. more uniqueness probability of Nash equilibria and asynchronous implementation). Despite these improvements, the sum-rate of the users does not increase because the proposed algorithm can not lead the power control game to an efficient equilibrium point. We solve this issue by modifying our algorithm such that the game is led to the equilibrium that satisfies a particular criterion. This criterion can be chosen by the designer to achieve a certain optimality among the equilibria. Furthermore, we propose the inexact method that helps us to boost the convergence speed of our modified algorithms. Lastly, we show that pricing algorithms can also be a special case of our modified algorithms. Simulations show a noticeable improvement in the sum-rate when we modify our proposed algorithm.

cs.GT↗

arXiv2014

Distributed Power Control in Multiuser MIMO Networks with Optimal Linear Precoding

Contractive interference functions introduced by Feyzmahdavian et al. is the newest approach in the analysis and design of distributed power control laws. This approach can be extended to several cases of distributed power control. One of the distributed power control scenarios wherein the contractive interference functions have not been employed is the power control in MIMO systems. In this paper, this scenario will be analyzed. In addition, the optimal linear precoder is employed in each user to achieve maximum point-to-point information rate. In our approach, we use the same amount of signaling as the previous methods did. However, we show that the uniqueness of Nash equilibria is more probable in our approach, suggesting that our proposed method improves the convergence performance of distributed power control in MIMO systems. We also show that the proposed power control algorithm can be implemented asynchronously, which gives a noticeable flexibility to our algorithm given the practical communication limitations.

cs.IT↗

arXiv2012

Transmission of non-linear binary input functions over a CDMA System

We study the problem of transmission of binary input non-linear functions over a network of mobiles based on CDMA. Motivation for this study comes from the application of using cheap measurement devices installed on personal cell-phones to monitor environmental parameters such as air pollution, temperature and noise level. Our model resembles the MAC model of Nazer and Gastpar except that the encoders are restricted to be CDMA encoders. Unlike the work of Nazer and Gastpar whose main attention is transmission of linear functions, we deal with non-linear functions with binary inputs. A main contribution of this paper is a lower bound on the computational capacity for this problem. While in the traditional CDMA system the signature matrix of the CDMA system preferably has independent rows, in our setup the signature matrix of the CDMA system is viewed as the parity check matrix of a linear code, reflecting our treatment of the interference.

cs.IT↗