Velocity estimation in wideband mobile stations equipped with multiple antennas

A new method is proposed for estimating the velocity of wideband mobile stations (MSs) equipped with multiple antennas. The MS speed is determined using the well-known relationship between the direction-of-arrivals (DOAs) and the Doppler frequency shifts experienced by the multipath signal components. The method is based on the assumption that the multipath signal components with the DOAs confined to a small angular interval are clustered in the delay domain. Additionally, we assume that different intervals of the DOAs correspond to different intervals of the propagation delays. The performance of the proposed method is assessed by simulations. The algorithm has a low computational cost and is therefore suitable for realtime implementations

A study of the influence of shadowing on the statistical properties of the capacity of mobile radio channels

This paper studies the influence of shadowing on the statistical properties of the channel capacity. The problem is addressed by using a Suzuki process as an appropriate statistical channel model for land mobile terrestrial channels. Using this model, exact solutions for the probability density function (PDF), cumulative distribution function (CDF), level-crossing rate (LCR), and average duration of fades (ADF) of the channel capacity are derived. The results are studied for different levels of shadowing, corresponding to different terrestrial environments. It is observed that the shadowing effect has a significant influence on the variance and the maximum value of the PDF and LCR of the channel capacity, but it has almost no impact on the mean capacity of the channel. The correctness of the theoretical results is confirmed by simulation using a stochastic channel simulator based on the sum-of-sinusoids principle. © 2008 Springer Science+Business Media, LL

The impact of shadowing and the severity of fading on the first and second order statistics of the capacity of OSTBC MIMO Nakagami-lognormal channels

This article presents a thorough statistical analysis of the capacity of orthogonal space-time block coded (OSTBC) multiple-input multiple-output (MIMO) Nakagami- lognormal (NLN) channels. The NLN channel model allows to study the joint effects of fast fading and shadowing on the statistical properties of the channel capacity. We have derived exact analytical expressions for the probability density function (PDF), cumulative distribution function (CDF), level-crossing rate (LCR), and average duration of fades (ADF) of the capacity of MIMO NLN channels. It is observed that an increase in the MIMO dimension or a decrease in the severity of fading results in an increase in the mean channel capacity, while the variance of the channel capacity decreases. On the other hand, an increase in the shadowing standard deviation increases the spread of the channel capacity, however the shadowing effect has no influence on the mean channel capacity. We have also presented approximation results for the statistical properties of the channel capacity, obtained using the Gauss-Hermite integration method. It is observed that approximation results not only reduce the complexity, but also have a very good fitting with the exact results. The presented results are very useful and general because they provide the flexibility to study the impact of shadowing on the channel capacity under different fading conditions. Moreover, the effects of severity of fading on the channel capacity can also be studied. The correctness of theoretical results is confirmed by simulations

Level-crossing rate and average duration of fades of the envelope of mobile-to-mobile fading channels in K-parallel dual-hop relay networks

This paper studies the fading behavior of narrowband mobile-to-mobile (M2M) fading channels in dual-hop distributed cooperative multi-relay systems under non-line-of-sight (NLOS) propagation conditions. M2M fading channels considered here are associated with amplify-and-forward relay networks, where K mobile relays are connected in parallel between the source mobile station and the destination mobile station. Such M2M fading channels are referred to as K-parallel dual-hop relay M2M fading channels. We study the fading behavior of these channels by analyzing the level-crossing rate (LCR) and the average duration of fades (ADF) of the received signal envelope. We derive analytical integral expressions of the aforementioned quantities along with the cumulative distribution function (CDF) of the envelope. These statistical quantities are derived assuming that the underlying stochastic processes are independent but not necessarily identically distributed. In addition, the statistical analysis pertaining to the special case of independent and identically distributed (i.i.d.) processes is also presented in this paper. The validity of the presented expressions is confirmed by simulations. Our results are very beneficial for future performance analysis of overall dual-hop distributed cooperative multi-relay systems

On the correlation and ergodic properties of the squared envelope of SOC Rayleigh fading channel simulators

In this paper, we investigate the correlation and ergodic properties of the squared envelope of a class of autocorrelation-ergodic (AE) sum-of-cisoids (SOC) simulation models for mobile Rayleigh fading channels. Novel closed-form expressions are presented for both the ensemble and the time autocorrelation functions (ACFs) of the SOC simulation model’s squared envelope. These expressions have been derived by assuming that the SOC model’s inphase and quadrature (IQ) components have arbitrary autocorrelation and cross-correlation properties. This consideration makes the results herein presented more general than those given previously in other papers, where it is assumed that the IQ components of the simulation model are strictly uncorrelated. We show that under certain conditions, the squared envelope of the SOC model is an AE random process. In addition, we evaluate the performance of three fundamental methods for the computation of the model parameters—namely the generalized method of equal areas, the L p -norm method, and the Riemann sum method—regarding their accuracy for emulating the squared envelope ACF of a reference narrowband Rayleigh fading channel model. The obtained results are important to design efficient simulators for the performance analysis of systems and algorithms sensitive to the correlation properties of the channel’s squared envelope, such as speed estimators and handover mechanisms

An RF-Based Positioning Method for Tracing a Cluster of Moving Scatterers in Non-Stationary Indoor Environments

Author's accepted manuscript© 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This letter presents a novel iterative positioning method for tracing the body segments of a person moving indoors using radio-frequency (RF) signals. The indoor space is equipped with a multiple-input multiple-output (MIMO) communication system. The person is modelled by a cluster of moving point scatterers, playing the role of moving body segments. The proposed technique estimates the time-variant (TV) positions of the moving scatterers by fitting the TV channel transfer function (TVCTF) of the channel model as close as possible to the TVCTF of the measured channels. Numerical results are presented to demonstrate the accuracy of this method.acceptedVersio

WiHAR : From Wi-Fi Channel State Information to Unobtrusive Human Activity Recognition

Author's accepted manuscript.© 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.acceptedVersio

Doppler Power Characteristics Obtained from Calibrated Channel State Information for Human Activity Recognition

Author's accepted manuscript.© 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.acceptedVersio

Human activity signatures captured under different directions using SISO and MIMO radar systems

In this paper, we highlight and resolve the shortcomings of single-input single-output (SISO) millimeter wave (mm-Wave) radar systems for human activity recognition (HAR). A 2 × 2 distributed multiple-input multiple-output (MIMO) radar framework is presented to capture human activity signatures under realistic conditions in indoor environments. We propose to distribute the two pairs of collocated transmitter–receiver antennas in order to illuminate the indoor environment from different perspectives. For the proposed MIMO system, we measure the time-variant (TV) radial velocity distribution and TV mean radial velocity to observe the signatures of human activities. We deploy the Ancortek SDR-KIT 2400T2R4 mm-Wave radar in a SISO as well as a 2 × 2 distributed MIMO configuration. We corroborate the limitations of SISO configurations by recording real human activities in different directions. It is shown that, unlike the SISO radar configuration, the proposed MIMO configuration has the ability to obtain superior human activity signatures for all directions. To signify the importance of the proposed 2 × 2 MIMO radar system, we compared the performance of a SISO radar-based passive step counter with a distributed MIMO radar-based passive step counter. As the proposed 2 × 2 MIMO radar system is able to detect human activity in all directions, it fills a research gap of radio frequency (RF)-based HAR systems.publishedVersio

A Trajectory-Driven 3D Channel Model for Human Activity Recognition

publishedVersio