Jonathan Rodriguez

Insole optical fiber sensor architecturefor remote gait analysis - an eHealth Solution

The advances and fast spread of mobile devices and technologies, we witness today, have extended its advantages over medical and health practice supported by mobile devices, giving rise to the growing research of Internet of Things (IoT), especially the e-Health field. The features provided by mobile technologies revealed to be of major importance when we consider the continuous aging of population and the consequent increase of its debilities. In addition to the increase of lifetime span of population, also the increase of health risks and their locomotive impairments increases, requiring a close monitoring and continuous evaluation. Such monitoring should be as noninvasive as possible, in order not to compromise the mobility and the day-to-day activities of citizens. Therefore, we present the development of a noninvasive optical fiber sensor (OFS) architecture adaptable to a shoe sole for plantar pressure remote monitoring, which is suitable to be integrated in an IoT e-Health solution to monitor the wellbeing of individuals. This paper explores the production of the OFS multiplexed network (using fiber Bragg gratings) to monitor the foot plantar pressure distribution during gait (walking movement). From the acquired gait data, it is possible to infer health conditions of the patient’s foot and spine posture. To guarantee the patients mobility, the proposed system consists of an OFS network integrated with a wireless transceiver to enable efficient ubiquitous monitoring of patients. This paper shows the calibration and measurement results, which reflect the accuracy of the proposed system, under normal walking in controlled area.

Energy-efficient game-theoretical random access for M2M communications in overlapped cellular networks

The unprecedented growth of machine-to-machine (M2M) devices has brought a heavy burden to traditional cellular networks. In this paper, we focus on the overload problem caused by massive connections of M2M devices in overlapped cellular networks. We formulate the joint base station (BS) selection and power allocation optimization problem for each M2M device as a noncooperative access game. The utility function of each M2M device is described as the success probability of random access weighted by the energy efficiency (EE). We propose an iterative energy-efficient game-theoretical random access algorithm, in which each M2M device searches its optimal strategies in turn until no M2M device is able to improve its individual utility with a unilateral deviation. Numerical results demonstrate that significant performance enhancements on both the delay and energy consumption can be achieved simultaneously.

Fundamentals of Antenna Design, Technologies and Applications

This chapter will deal with the concepts, requirements, challenges and the evolution of antenna technologies, driven by subsequent releases of mobile generations from legacy 3G (Third Generation Mobile Systems) towards the latest release in LTE-A in particular. This chapter gives a brief overview of the latest techniques used to achieve several antenna designs for different applications. We also within this chapter provide concrete and practical examples of widely adopted multi-band, wideband, MIMO, balanced and mm-wave antenna technologies for current 3G and 4G mobile systems as well as for the forthcoming 5G era. Issues including design considerations, engineering design, measurement setup and methodology and practical applications are all covered in depth.

Simple and Compact Planar Ultra-Wideband Antenna with Band-Notched Characteristics

This chapter addresses an approach to achieve the ultra-wideband (UWB) spectrum as well as discusses the phenomena of frequency interference within UWB antennas. The antenna consists of a hexagonal-shaped structure printed over FR4 substrate. For bandwidth improvement, defected ground structure (DGS) was first introduced, and, secondly, a stub was added in the feeding strip to achieve a larger bandwidth. To achieve the frequency band-notched characteristics, a half hexagonal slot was etched on the radiator, which creates a notch at 5.2 GHz, and then by introducing a full hexagonal slot, another rejected band was produced at 10 GHz. The outcomes also confirm the proposed UWB antenna design can achieve superior dual band-notch performance at desired frequency bands.

Performance of Dual-Band Balanced Antenna Structure for LTE Applications

Dual-band LTE antenna with balanced structures is modelled and analysed within this chapter. The obtained antenna occupies a compact volume of 50 × 100 × 4 mm3. To feed the balanced antenna structure with unbalanced coaxial feeding, a wide band balun is designed and incorporated on the bottom side of the antenna ground plane. This brings such a significant feature of the proposed antenna, in which both the antenna and integrated balun are considered as a single-layer system device. The antenna is fabricated as a standalone device as well as along with incorporated balun. The calculated and measured outcomes in free space and handheld cases are achieved and compared. The main characteristics such as reflection coefficient, far-field patterns, power gains and efficiency are said to be in good agreement.

Miniaturized Monopole Wideband Antenna with Tunable Notch for WLAN/WiMAX Applications

A tunable notched band small monopole antenna is studied and investigated in this chapter. The rejected band was achieved by introducing an additional inner crescent shape along with an outer shape over the surface of the substrate. By placing a small capacitor (varactor) between the inner and outer arches, the center frequency of each notch can be individually shifted downward. The antenna exhibits a wide impedance bandwidth from 1.5 to 5 GHz with good impedance matching (VSWR ≤2) and a tunable range of band rejection frequency (center frequency from 2.38 to 3.87 GHz). To validate the theoretical results, the antenna is fabricated and tested. Simulated and measured results are presented and show a wideband impedance bandwidth with a reconfigurable notched band, stable radiation patterns, and constant gain.

A privacy-enhanced OAuth 2.0 based protocol for Smart City mobile applications

In the forthcoming Smart City scenario, Service Providers will require users to authenticate themselves and authorize their mobile applications to access their remote accounts. In this scenario, OAuth 2.0 has been widely adopted as a de facto authentication and authorization protocol. However, the current OAuth 2.0 protocol specification does not consider the user privacy issue and presents several vulnerabilities that can jeopardize users privacy rights. Therefore, in this paper we propose an OAuth 2.0 based protocol for Smart City mobile applications that addresses the user privacy issue by integrating a pseudonym-based signature scheme and a signature delegation scheme into the OAuth 2.0 protocol flow. The proposed solution allows users to self-generate user-specific and app-specific pseudonyms on-demand and ensure privacy-enhanced user authentication at the Service Provider side. The proposed protocol has been validated with Proverif and its performance has been evaluated in terms of time and space complexity. Results show that the proposed protocol can provide users with efficient and effective means to authenticate towards service providers while preventing user tracking and impersonation from malicious entities located in the network side or in the users mobile device.

Practical multi-band antenna for 3G and 4G mobile services

This paper presents a compact antenna design based on PIFA configuration with multi-band features. The present design operates over the lower and upper bands of LTE700/2600MHz, together with the existing standard of GSM1900MHz. An approach of size miniaturization and triple band characteristics was applied through the embedded slot over the radiator surface. The antenna occupies a small volume of 13.5×50×7mm3, which is mounted over the ground plane with dimensions of 50×100mm2. Moreover, two identical antennas are integrated within the home device, where their results are checked and compared with the standalone version of the antenna.

Patch antenna for integration in AUN based access control system

This paper discusses the design and implementation of an RFID-based access control system for use in a University campus. This systems design begins with the design of a power-efficient and cheap passive 125Khz RFID tags and reader antennae using the HFSS software. The key antenna design goals are miniaturization, power efficiency (passive RFID), linear polarization and a narrow beam/gain width. The patch antenna is then used as the driving component of the implemented access control system by interfacing its reader module with an Arduino Mega 2560 microcontroller which is linked to a door via a relay thus granting only valid RFID Tags access to these doors while keeping track of tags used to access the door. As such, a patch antenna is used to control access to the door using Radio Frequency Identification.

Demonstration of structural changes in variable structure control using state space approach

This paper demonstrates structural changes in variable structure control. A second order open loop unstable system was used as an illustrative example to demonstrate the structural changes; the system has real, positive open loop eigenvalues. A change of system eigenvalues implies a change of system structure. A structure may have properties such as being stable or unstable, fast/sluggish response, and insensitive to all inputs including disturbances. Thus the strategy of variable structure control is to provide the system with a means of switching from one structure to another with a view to exploiting the useful properties available in both structures. The bonus is that it is possible to arrive at a completely different lower order-structure which is totally insensitive to disturbances and internal parameter uncertainties.