Beatriz Sedano

Energy harvesting technologies for low-power electronics

Power consumption is one of the most critical issues when designing low-cost electronic devices, such as sensing nodes in wireless sensor networks. To support their operation, such systems usually contain a battery; however, when the battery has consumed all its energy, the node (e.g. the sensor) must be retrieved and the battery replaced. If the node is located in a remote and non-accessible placement, battery replacement can become an expensive (and even impossible) task. This way, energy harvesting has emerged as a suitable alternative to supply low-power electronic systems, by converting ambient energy into electric power. Scavenged energy can be used to directly supply the circuits, or stored to be used when needed. This paper summarises the power needs of a general wireless sensor node and describes the main principles of most representative energy harvesting technologies. Copyright

Implementation and validation of an Angle of Arrival (AOA) determination system

This paper presents the implementation and validation of a complete AoA (Angle of Arrival) system. The AoA system is typically used together with smart antenna technology. In this paper the AoA system is part of a mobile wireless communication positioning system. The implementation includes the array antenna, the front ends and the AoA estimation block, which uses the MUSIC algorithm. Furthermore, a complete AoA system model has been developed, and used to find the optimum configuration of the AoA system. The AoA system has been validated using the model implemented in MATLAB.

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.

On-Board Electromagnetic Interference Field-Test and Evaluation of a Non-electrified Railway Regional Line

In order to assess the performance of the wireless communication systems, a railway line is characterised through the identification of electromagnetic interferences (EMI). The aim of this paper is to show the strategy to identify EMI on field as well as the results obtained. First, the need of the analysis and the objectives of the measurement campaign in a non-electrified Italian Regional Railway line between Caligari and San Gavino are shown. After that, the measurement setup developed for the tests is described. Then, the description of the measurement campaign carried out is exposed. Finally, the measurement results are presented. The results show that the frequency bands of GSM, UMTS and Italian 4G are in the frequency ranges where the highest powered signal (around 800 MHz–900 MHz, 1.8 GHz and 1.9 GHz), on the other hand GPS L1 and Galileo E1frequency band is not impacted by any kind of interference signal.

Analysis of YouTube’s traffic adaptation to dynamic environments

The popular Internet service, YouTube, has adopted by default the HyperText Markup Language version 5 (HTML5). With this adoption, YouTube has moved to Dynamic Adaptive Streaming over HTTP (DASH) as Adaptive BitRate (ABR) video streaming technology. Furthermore, rate adaptation in DASH is solely receiver-driven. This issue motivates this work to make a deep analysis of YouTube’s particular DASH implementation. Firstly, this article provides a state of the art about DASH and adaptive streaming technology, and also YouTube traffic characterization related work. Secondly, this paper describes a new methodology and test-bed for YouTube’s DASH implementation traffic characterization and performance measurement. This methodology and test-bed do not make use of proxies and, moreover, they are able to cope with YouTube traffic redirections. Finally, a set of experimental results are provided, involving a dataset of 310 YouTube’s videos. The depicted results show a YouTube’s traffic pattern characterization and a discussion about allowed download bandwidth, YouTube’s consumed bitrate and quality of the video. Moreover, the obtained results are cross-validated with the analysis of HTTP requests performed by YouTube’s video player. The outcomes of this article are applicable in the field of Quality of Service (QoS) and Quality of Experience (QoE) management. This is valuable information for Internet Service Providers (ISPs), because QoS management based on assured download bandwidth can be used in order to provide a target end-user’s QoE when YouTube service is being consumed.

High-Isolation and Wide-Band 180º Hybrids Based on Electronically Tunable Lumped-Element Filters

A new high isolation lumped-element 180 - hybrid, using electronically adjustable fllters with varactor diodes, are proposed. This design is very simple and based on only two conflgurable low order (N = 2) fllters. Due to the limited tuning frequency range of varactor diodes, maximum near-octave frequency coverage of 2.5{5GHz was planned in the high isolation hybrid. An impressive simulated typical isolation in the range of > 60dB was achieved. One of the typical applications of developed hybrids could be the conversion of 70MHz IF to microwave frequencies, with broadband mixers in single-conversion converters and very high LO rejection (> 60dB).

Low power considerations and design for CMOS VCOs applied for direct conversion receivers at 5GHz

Low power design often requires direct conversion architectures, such as low-IF or zero-IF. Any of these two possibilities needs a low power, low phase noise voltage control oscillator (VCO) in the frequency synthesizer. This work is focused on low power considerations applied to the practical modern conception of this device. Fulfilling the standard specifications (output power, phase noise, frequency range) should be completed with this deeper step. A conscious design leads moreover to an improvement in the results obtained by the classical considerations. The increase of the quality factor of the passive elements is one of the key points, followed by an accurate design of the architecture scheme. Furthermore, lower current consumption provides higher oscillation frequencies and facilitates higher frequency ranges, which follow the trends of modern wireless and wideband communication standards. In order to validate the aforementioned assumptions, a CMOS VCO has been implemented in UMC 0.18μm 1P6M technology, with power consumption down to 3.4mW.