Jon Legarda

Design of UWB folded-plate monopole antennas based on TLM

From the current distribution on planar monopoles, transmission line modeling is applied to study this kind of antennas. Some reported techniques for broadband monopoles are approached by using this model from a qualitatively point of view. Conclusions are derived that help to match the monopoles over an ultrawide bandwidth regardless of whether they are folded or not. Folded configurations are obtained in order to provide solutions to specific designs and improve radiation pattern maintaining the planar monopole broadband behavior. Three compact folded prototypes with greater than 1:38 bandwidth are implemented and tested. Pulse distortion is also discussed for this type of applications.

WebTag: Web Browsing into Sensor Tags over NFC

Information and Communication Technologies (ICTs) continue to overcome many of the challenges related to wireless sensor monitoring, such as for example the design of smarter embedded processors, the improvement of the network architectures, the development of efficient communication protocols or the maximization of the life cycle autonomy. This work tries to improve the communication link of the data transmission in wireless sensor monitoring. The upstream communication link is usually based on standard IP technologies, but the downstream side is always masked with the proprietary protocols used for the wireless link (like ZigBee, Bluetooth, RFID, etc.). This work presents a novel solution (WebTag) for a direct IP based access to a sensor tag over the Near Field Communication (NFC) technology for secure applications. WebTag allows a direct web access to the sensor tag by means of a standard web browser, it reads the sensor data, configures the sampling rate and implements IP based security policies. It is, definitely, a new step towards the evolution of the Internet of Things paradigm.

UWB Staircase-Profile Printed Monopole Design

In printed monopoles, the current distribution along the lower monopole sheet and upper groundplane edges can be made analogous to a transmission line distribution by an appropriate antenna feed design. Accordingly, the VSWR < 2 impedance bandwidth upper frequency limit can be estimated for staircase-profile printed 2D ultrawideband (UWB) monopoles. Following this guideline, three tailored-bandwidth prototypes are designed, implemented and measured. They retain their length and width while multiplying their upper frequency (4.87, 8.7, and 15.15 GHz) by the number of monopole profile steps (1, 2, and 3). The deviation is found mainly below 13% in relation to the reference formula. The concept of angular range based on pattern stability factor (PSF) is introduced to compare the solid angle of UWB pattern stability operation when increasing the bandwidth. The angular range degradation versus impedance bandwidth improvement shows all the possible performance levels of the antennas. Thus, the design of UWB printed monopoles is approached from both points of view, i.e., impedance bandwidth and pattern stability.

Implementation Details and Safety Analysis of a Microcontroller-based SIL-4 Software Voter

This paper presents a microcontroller-based software voting process that complies with Safety Integrity Level-4 (SIL-4) requirements. The selected system architecture consists of a 2 out of 2 schema, in which one channel acts as Master and the other as Slave. Each redundant channel uses a microcontroller as central element. The present analysis demonstrates that this system fulfills SIL-4 requirements. Once the system architecture is detailed, the system overall functionality and the data flow are presented. Then, the microcontrollers internal architecture is explained, and the software voting process flow-diagram is discussed. Afterward, the resources of the microcontroller architecture that are used for the execution of each task involved in the software voting process (hardware-software interaction) are determined. Finally, a fault analysis is elaborated to demonstrate that the cases in which the safety requirements are compromised have a very small occurrence probability, i.e., the hazard rate of proposed voting is below 1E-9.

Multi-residential gateway: an innovative concept and a practical approach

A new concept of multi-residential gateway (MRG) capable of managing several residential units (e.g. homes, flats) simultaneously while offering new additional services is presented. Apart from the typical recommendations proposed for residential gateways, specific new requirements are introduced in order to overcome the multi-residential challenge. A novel MRG has been developed fulfilling all the previous constrains. Both the core and the management architectures are explained, with particular emphasis on the networking aspects and its modular firewall/QoS design. An OSGi based platform has been introduced as the best management framework, and its validation is done with the addition of a MRG parental control service.

An Agent Based Semantic OSGi Service Architecture

The OSGi Framework offers a cooperative environment for the deployment and management of services for multidisciplinary software applications, achieving interoperability between systems. But even so, its service registry lack of non-syntactic information prohibits agents making this framework available for a wider range of applications. This paper proposes an agent-based novel architecture with a semantic in-memory OSGi service registry based on OWL. It enhances the potential of OSGi with semantic data extracted from services deployed in the framework, using software agents in conjunction with Java Annotations and Java Reflection API to dynamically obtain and invoke all required information. As a result, service development and deployment in the OSGi framework will get another view, avoiding the commonly used Interfaces pattern. This Architecture has been successfully applied to a domotic environment managed by a Service Residential Gateway (SRG).

Ultra low-power smart medical sensor node for in-body Biomonitoring

New advances in biosensor and electronic technologies will merge in new health assistance paradigms strongly based on the remote Biomonitoring. Biomedical circuit and systems have much to say on this, as for example the central venous catheters (CVC). Central venous catheters are commonly used in clinical practice to improve a patients quality of life. Nevertheless, there remains a large risk of infection associated with microbial biofilm (about 80% of all human bacterial infections). The standardization bodies, the radiofrequency devices and the biosensor technology are taking their positions, and the integration of all that effort is the work proposed in this paper. An ultra-low power active medical implant is presented for in-body monitoring of Electrical Bioimpedances (EBI) based sensors. A detailed and exhaustive lifetime evaluation has been done based on two typical monitoring parameters: the frequency of the internal sensor measuring and the frequency of external communication requests. The results show up to 20 months lifetime powered with a 50mA coin-cell battery.

High-Resolution ACLR Measurement Architecture for Adaptive Feedforward Amplifiers

One of the most restrictive linearity constraints to RF transmitter nonlinearity is the unwanted emission immediately outside the channel bandwidth, mostly known as adjacent channel leakage ratio (ACLR). In this paper, novel architecture design rules are presented for ACLR-level measurement in feedforward adaptive amplifiers. Both main and distortion signal power levels are obtained without any masquerading effect and with minimum component utilization. A prototype implementation is introduced to validate the proposed design rules, and a commercial spectrum analyzer is used for accuracy checking. Finally, the thermal stability has been tested for the -20degC to 70degC range.

A novel QoS architecture for multi-service provisioning in multi-residential gateways

The residential gateway (RG) is known as the connection box that provides multi-service access to the consumer networks. This work is focused on a multi-residential gateway (MRG) concept, which offers more service provisioning and management capabilities. The QoS support in this context is challenging, as new requirements must be fulfilled regarding such multi-network and multiservice environment. Both design and development processes are shown in depth and the proposed solution is tested and compared with the main trends among the state of the art. This paper provides an optimum multi-service QoS provisioning architecture for multi-residential units as the best trade off between packet loss and delay performances. The implemented test bed (with VoIP, Interactive Video, Telnet, Web, FTP and Bulk traffic provisioning through up to 20 simultaneous consuming units) validates this design and provides some interesting future works.

An experimental study on the applicability of SYN cookies to networked constrained devices

The Internet protocol suite is increasingly used on devices with constrained resources that operate as both clients and servers within the Internet of Things paradigm. However, these devices usually apply few—if any—security measures. Therefore, they are vulnerable to network attacks, particularly to denial of service attacks. The well‐known SYN flood attack works by filling up the connection queue with fake SYN requests. When the queue is full, new connections cannot be opened until some entries are removed after a time‐out. Class 2 constrained devices—according to the RFC 7228—are highly vulnerable to this attack because of their limited available memory, even in low‐rate attacks. This paper analyses and compares in a class 2 constrained device the performance of 2 commonly used defence mechanisms (ie, recycle half‐open connections and SYN cookies) during a low‐rate SYN flood. We first review 2 SYN cookies implementations (ie, Linux and FreeBSD) and compare them with a hybrid approach in a class 2 device. Finally, experimental results prove that the proposed SYN cookies implementation is more effective than recycling the oldest half‐open connections.