Velázquez, Ramiro
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Preferred name
Velázquez, Ramiro
Official Name
Velázquez Guerrero, Ramiro
Alternative Name
rvelazquez
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ORCID
Scopus Author ID
7003505296
Researcher ID
GQW-6348-2022

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A Non-WSSUS Channel Simulator for V2X Communication Systems

2020 , José Jimmy Jaime-Rodríguez , Carlos Antonio Gómez-Vega , Gutierrez, Carlos A. , José Martín Luna-Rivera , Daniel Ulises Campos-Delgado , Velázquez, Ramiro

This paper presents a simulator of non-wide sense stationary uncorrelated scattering (non-WSSUS) multipath fading channels for the performance analysis of vehicle-to-everything (V2X) communication systems. The proposed simulator is constructed with the combination of the Monte Carlo and sum-of-cisoids (SOC) principles, and it is suitable for multicarrier transmission schemes such as those defined for dedicated short-range communications (DSRC) and cellular-based V2X (C-V2X) communications. The channel simulator provides an accurate and flexible solution to reproduce the time and frequency (TF) correlation properties of non-WSSUS vehicular channels under arbitrary isotropic and non-isotropic scattering conditions. Furthermore, the proposed simulator allows velocity variations and non-linear trajectories of the mobile stations (MSs). To demonstrate the practical value of the presented simulator, we evaluate the bit error rate (BER) performance of two channel estimation techniques that are considered for IEEE 802.11p transceivers, namely the least squares (LS) estimator and the spectral temporal averaging (STA) technique. The BER performance of both channel estimators was analyzed by considering three propagating scenarios for road safety applications. Our results show that the non-stationary characteristics of the vehicular multipath fading channel have nearly no effects on the LS estimator’s BER performance. In contrast, the performance of the STA estimator is significantly affected by the channel’s non-stationary characteristics. A variation of the original STA technique that applies only a temporal averaging is introduced in this work to improve the system’s BER in non-WSSUS channels.

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Insights into the Capabilities of Tactile-Foot Perception

2012 , Velázquez, Ramiro , Omar Bazán , Varona, Jorge , Delgado-Mata, Carlos , Gutierrez, Carlos A.

This paper presents a novel wearable interface for the foot: a shoe-integrated tactile display that enables users to obtain information through the sense of touch via their feet. A 16-point array of actuators stimulates the sole of the foot by inducing different vibration frequencies. A series of experiments were conducted with 20 sighted and 5 blind voluntary subjects to evaluate the role of tactile perception by the human foot and the tactile sensitivity of the plantar surface. Tests evaluated the perception of simple shapes, patterns and directional instructions. The results showed that some information is discriminable and that tactile-foot stimulation could be used for a wide number of applications in human-machine interaction. Furthermore, the results also suggested that the blind perform better in some key tasks and support the feasibility of footwear providing tactile feedback for situational awareness, mobility and the navigation assistance of the blind.

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Monitoring Improvement on Reactive, Proactive and Hybrid Protocols of Wireless Sensor Networks

2019 , Del-Valle-Soto, Carolina , Velázquez, Ramiro , Gutierrez, Carlos A. , Valdivia, Leonardo , Del-Puerto-Flores, J. Alberto

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Performance of MRC Detection in OFDM System with Virtual Carriers over V2V Channels

2019 , Del-Puerto-Flores, J. Alberto , Joaquin Cortez , Gutierrez, Carlos A. , Del-Valle-Soto, Carolina , Velázquez, Ramiro , Valdivia, Leonardo

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Modeling and control techniques for electric powered wheelchairs: An overview

2014 , Velázquez, Ramiro , Gutierrez, Carlos A.

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Design and Construction of a New Door Driving Mechanism for Mexico's City Metro

2018 , Magos-Rivera, Miguel , Velázquez, Ramiro , Gomez, Antonio S. , Gutierrez, Carlos A.

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A Differential-Drive Mobile Robot Driven by an Ethology Inspired Behaviour Architecture

2012 , Delgado-Mata, Carlos , Velázquez, Ramiro , Gutierrez, Carlos A.

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A Differential-Drive Mobile Robot Driven by an Ethology Inspired Behaviour Architecture

2012 , Delgado-Mata, Carlos , Velázquez, Ramiro , Gutierrez, Carlos A.

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Bit error rate performance analysis of vehicular communication systems considering velocity variations of the mobile stations

2017 , C.A. Gomez-Vega , J.J. Jaime-Rodriguez , Gutierrez, Carlos A. , Velázquez, Ramiro

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Wearable Urban Mobility Assistive Device for Visually Impaired Pedestrians Using a Smartphone and a Tactile-Foot Interface

2021 , Tachiquin, Ricardo , Velázquez, Ramiro , Del-Valle-Soto, Carolina , Gutierrez, Carlos A. , Miguel Carrasco , Roberto De Fazio , Andrés Trujillo-León , Paolo Visconti , Fernando Vidal-Verdú

This paper reports on the progress of a wearable assistive technology (AT) device designed to enhance the independent, safe, and efficient mobility of blind and visually impaired pedestrians in outdoor environments. Such device exploits the smartphone’s positioning and computing capabilities to locate and guide users along urban settings. The necessary navigation instructions to reach a destination are encoded as vibrating patterns which are conveyed to the user via a foot-placed tactile interface. To determine the performance of the proposed AT device, two user experiments were conducted. The first one requested a group of 20 voluntary normally sighted subjects to recognize the feedback provided by the tactile-foot interface. The results showed recognition rates over 93%. The second experiment involved two blind voluntary subjects which were assisted to find target destinations along public urban pathways. Results show that the subjects successfully accomplished the task and suggest that blind and visually impaired pedestrians might find the AT device and its concept approach useful, friendly, fast to master, and easy to use.

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