Luis Enrique Díez

• Doctor of Engineering
• Research Assistant at University of Deusto

The availability of raw Global Navigation Satellites System (GNSS) measurements in Android smartphones fosters advancements in high-precision positioning for mass-market devices. However, challenges like inconsistent pseudo-range and carrier phase observations, limited dual-frequency data integrity, and unidentified hardware biases on the receiver...

Smartphone-based positioning, heralded for its widespread accessibility, encounters challenges due to its reliance on Global Navigation Satellite Systems (GNSS) in unfavorable conditions such as urban canyons, tunnels, and indoor areas. Even in clear-sky conditions, signal distortions, interruptions, and the limitations of cost-effective smartphone...

Ultra-wideband (UWB) is a key technology that enables the evolution of localization systems and makes it possible to provide more and better location-based services. However, the accuracy of the localization system decreases when the localization devices are worn by human beings, because in some conditions they obstruct the line of sight (LOS) betw...

The steady increase in the number of elderly citizens represents a likelihood of an increased burden on the family, government, healthcare, and social services since many of these elderly people cannot live independently without assistance from a caregiver. As such, there is an increase in demand for services in terms of technologies to address the...

Prior work has shown the classification of voiding dysfunctions from uroflowmeter data using machine learning. We present the use of smartwatch audio, collected through the UroSound platform, in order to automatically classify voiding signals as normal or abnormal, using classical machine learning techniques. We train several classification models...

Leveraging consumer technology such as smartwatches to objectively and remotely assess people with voiding dysfunction could capture unique features for prompt diagnosis of a disease. This paper presents the UroSound, the first platform that performs non-intrusive sound-based uroflowmetry with a smartwatch. We study the feasibility of using a smart...

With the popularization of machine learning (ML) techniques and the increased chipset’s performance, the application of ML to pedestrian localization systems has received significant attention in the last years. Several survey papers have attempted to provide a state-of-the-art overview, but they usually limit their scope to a particular type of po...

Thanks to its ability to provide sub-meter level positioning accuracy, Ultrawideband (UWB) has found wide use in several wireless body area network (WBAN) applications such as ambient assisted living, remote patient management and preventive care, among others. In spite of the attractiveness of UWB, it is not possible to achieve this level of accur...

Vehicular positioning systems are necessary for the development of autonomous vehicles and advanced driver assistance systems (ADAS). In recent years, Inertial Measurement Units (IMU) based on micro-electromechanical systems (MEMS) have been included in proposals for multi-sensor positioning system architectures in order to take advantage of their...

In recent years, Ultrawideband (UWB) has become a very popular technology for time of flight (TOF) based localization and tracking applications, where target sensors could be mounted on or close to the human body which may raise non-line-of-sight (NLOS) and quasi-line-of-sight (QLOS) cases and lead to significant ranging errors. While most UWB loca...

Ultrawideband (UWB) has the ability to achieve decimetre level of ranging accuracy, hence, its wider usage nowadays in the field of positioning. In spite of the attractiveness of UWB, its performance is strongly dependent on the propagation channel. In this paper, an analysis of the the UWB channel for ranging applications using an inhouse develope...

The integration of candidate sensors such as a microelectromechanical system-based inertial measurement unit (MEMS IMU) for localization and navigation has been widely explored for vehicular, pedestrian and robotics applications. They also arise as candidate sensors in the train navigation context and their integration in safety relevant applicatio...

Over the years, several Ultrawideband (UWB) localization systems have been proposed and evaluated for accurate estimation of the position for pedestrians. However, most of them are evaluated for a particular wearable sensor position; hence, the accuracy obtained is subject to a given wearable sensor position. This paper is focused on studying the e...

Over the years, several UWB localization systems have already been proposed for accurate position estimation of pedestrians. Most of these systems already proposed for pedestrian localization have only been individually evaluated for a particular wearable sensor position. In this paper, we compare the positioning performance of seven body wearable...

In recent years, several Ultrawideband (UWB) localization systems have already been proposed and evaluated for accurate position estimation of pedestrians. However, most of them are evaluated for a particular wearable sensor position; hence the accuracy obtained is subject to a given wearable sensor position. In this paper, we study the effects of...

The first formal attempt to standardize the test and evaluation of localization systems was the ISO/IEC 18305 standard. As reviewed in this paper, the ISO/IEC 18305 provides guidelines to evaluate an indoor localization system as a black box. Such evaluation is useful for end users, but not fully useful for either developers or researchers. As a re...

In recent years, Ultrawideband (UWB) has become a very popular technology for time of flight (TOF) based localization and tracking applications but its human body interactions have not been studied yet extensively. Most UWB systems already proposed for pedestrian ranging have only been individually evaluated for a particular wearable sensor positio...

In time-of-flight (TOF)-based human ranging systems, target sensors are often mounted on or close to the human body, which may raise non-line-of-sight (NLOS) cases and lead to significant ranging errors depending on the relative position between the body, transmitter (Tx), and receiver (Rx). In recent years, ultrawideband (UWB) has become a very po...

Inertial sensors are included in most of the current smart devices and many researchers have identified their ability to be used for analyzing different parameters of human behavior. Among them, the pedestrian’s step length provides very useful information for different applications, such as pedestrian dead reckoning positioning or gait analysis. D...

Vehicular Ad-Hoc Networks (VANETs) have attracted a high interest in recent years due to the huge number of innovative applications that they can enable. Some of these applications can have a high impact on reducing Greenhouse Gas emissions produced by vehicles, especially those related to traffic management and driver assistance. Many of these ser...

Integrating new candidate sensors, such as Global Navigation Satellite System (GNSS) and inertial measurement unit (IMU), into fail-safe train positioning systems have recently become a prominent area of research. Although there are a number of contributions related to the design of data fusion algorithms, the lack of details in raw measurements an...

Wearable devices seem an ideal option for implementing pedestrian dead-reckoning (PDR) systems and, eventually, providing seamless Location Based Services (LBS). Among the different available wearable devices, wrist-worn devices, such as smartwatches, have great potential due to their featuring more and more sensors and their convenience for the us...

Many dependents such as children, elderly or disabled people get lost or missing, but as handicapped people, they often lack the skills to protect themselves, and tutors cannot keep their dependents in sight all of the time. Therefore, the challenge to be tackled in this paper is to develop a dependents’ cooperative location network over which tuto...

Wearable devices are a key driver for the development of pedestrian navigation systems. In this work, we consider inertial navigation systems (INSs). There is a diversity of such INSs. Normally, the comparison of INSs is restricted to indoor environments, or to outdoor small areas. However, it is of interest to study the behaviour of INSs in large...

Positioning accurately and safely a train is nowadays a great challenge. That includes currently available railway sensors and new candidate sensors for data fusion. Global Navigation Satellite System (GNSS) and Inertial Measurement Unit (IMU) sensors arise as prominent technologies to incorporate in railways. Although satellite-based train localiz...

In this paper, we present an offline map matching technique designed for indoor localization systems based on conditional random fields (CRF). The proposed algorithm can refine the results of existing indoor localization systems and match them with the map, using loose coupling between the existing localization system and the proposed map matching...

Location based services can improve the quality of patient care and increase the efficiency of the healthcare systems. Among the different technologies that provide indoor positioning, inertial sensors based pedestrian dead-reckoning (PDR) is one of the more cost-effective solutions, but its performance is limited by drift problems. Regarding the h...

This paper studies how the accuracy of the step detection algorithm of a pedestrian dead- reckoning (PDR) system is affected by the sampling frequency and the filtering of the data gathered from a wrist-worn inertial measurement unit (IMU). On the one hand, results show that sensors sampling rate can be reduced and a similar accuracy can still be o...