PROENERGY-WSN: Prototypes for Efficient Energy Self-sustainable Wireless Sensor Networks

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Experimental Characterization of Wearable Antennas and Circuits for RF Energy Harvesting in WBANs

Publication . Saraiva, Henrique Morais; Borges, Luís M.; Pinho, Pedro; Gonçalves, Ricardo; Chavez-Santiago, Raul; Barroca, Norberto; Tavares, Jorge; Gouveia, Paulo T.; Carvalho, Nuno Borges; Balasingham, Ilangko; Velez, Fernando J.; Loss, Caroline; Salvado, Rita

Field trials have been performed in Covilhã to identify the spectrum opportunities for radio frequency (RF) energy harvesting through power density measurements from 350 MHz to 3 GHz. Based on the identification of the most promising opportunities, a dual-band printed antenna was conceived, operating at GSM bands (900/1800), with gains of 1.8 and 2.06 dBi, and efficiency varying from 77.6 to 82%, for the highest and lowest operating frequency bands, respectively. In this paper, guidelines for the design of RF energy harvesting circuits and choice of textile materials for a wearable antenna are briefly discussed. Besides, we address the development and experimental characterization of three different prototypes of a five-stage Dickson voltage multiplier (with and without impedance matching circuit) responsible for RF energy harvesting. All the three prototypes (1, 2 and 3) can power supply the sensor node for RF received powers of 2 dBm, -3 dBm and -4 dBm, and conversion efficiencies of 6, 18 and 20%, respectively.

2014-05Conference object

Open access

Developing Sustainable Communication Interfaces Through Fashion Design

Publication . Loss, Caroline; Salvado, Rita; Lopes, Catarina; Pinho, Pedro; Gonçalves, Ricardo; Velez, Fernando J.; Saraiva, Henrique Morais; Tavares, Jorge; Barroca, Norberto; Borges, Luís M.

The recent technological developments made electronic devices become imperative and indispensable, being present in our daily routines, all over the world. But, the continuous exposition of people to the electromagnetic radiation might cause illness. Electrosmog is the invisible electromagnetic radiation that results from the usage of electric equipment and wireless technologies. Some studies present electro sensibility as a contemporary illness affecting more and more people. This paper analyses some of the challenges this reality puts to the fashion design and how textile materials may be used to protect the human body against the harmful radiation and to develop smart cloths incorporating textile antennas able to capture these radiations and feed low-frequency devices. Thus, one considers the notion of “Transparent Sustainability” and the search for the smart energy explorations of/or in the human body. This way, the association of fashion design and technology can transform the garment in a sustainable communication interface.

2014-06Conference object

Open access

A Model for Mapping between the Quality of Service and Experience for Wireless Multimedia Applications

Publication . Robalo, Daniel; Velez, Fernando J.

With nowadays evolution of wireless network technologies and the growth of novel wireless multimedia services it is critical for network and service providers to be able to assess user's perceptual multimedia quality, for commercial and technical reasons. As so, we present wireless network services and applications characterization requirements, updated to current specifications. We considered recommendations for some major regulations entities, such as the ITU, 3GPP, WiMAX Forum and the European project EU-MESH. In the case of audio and video applications, the latest and most used encoding schemes were addressed by considering the WiMAX Forum recommendations. In turn, as not only the Quality of Service (QoS) needs to be addressed, we propose a model for the mapping between QoS parameters and user's Quality of Experience (QoE) for multimedia applications. Measurable QoS parameters can be gathered throughout the network and mapped into an effective QoE estimation. The model has been obtained by means of mathematical regression and the fittings are validated by analysing the coefficient of determination, R2, between the results from our model and MOS experimental values. The achieved results are R2 = 0.94, 0.84 and 0.98 for gaming, video and audio, respectively. The corresponding mean square error is approximately zero in all cases.

2014Conference object

Open access

Fundamental Limits for LTE Radio and Network Planning

Publication . Velez, Fernando J.; Acevedo Flores, Jessica; Robalo, Daniel

A comprehensive study on the variation of the carrier-to-noise-plus-interference ratio (CNIR) with different system parameters is of fundamental importance in the context of LTE planning. For cellular planning purposes, the UL and DL CNIRs from/at the mobile station are very important parameters, although we are only considering DL in this work. From a detailed analysis of its variation with the coverage and reuse distances for different modulation and coding schemes (MCS) and given empirical propagation models, an evaluation of the possible range for the reuse pattern is performed. By considering the CQI and reference CNIR requirements recommended by 3GPP. DL peak bit rates along with the Transport Block Size (TBS) assumed for single stream and bandwidth of 5 MHz, physical and supported throughputs are analysed. These formulations shows the clear decrease of the supported throughput for the longest coverage distances in the LTE 2.6 GHz band, a behaviour that is not so clear at 800 MHz, and gives hints to the optimization of the use of different frequency bands in the optimization of carrier aggregation between two different bands in LTE-A scenarios.

2015-09Conference object

Open access

Radio‐frequency energy harvesting for wearable sensors

Publication . Borges, Luís M.; Chávez‐Santiago, Raul; Barroca, Norberto; Velez, Fernando José; Balasingham, Ilangko

The use of wearable biomedical sensors for the continuous monitoring of physiological signals will facilitate the involvement of the patients in the prevention and management of chronic diseases. The fabrication of small biomedical sensors transmitting physiological data wirelessly is possible as a result of the tremendous advances in ultra-low power electronics and radio communications. However, the widespread adoption of these devices depends very much on their ability to operate for long periods of time without the need to frequently change, recharge or even use batteries. In this context, energy harvesting (EH) is the disruptive technology that can pave the road towards the massive utilisation of wireless wearable sensors for patient self-monitoring and daily healthcare. Radio-frequency (RF) transmissions from commercial telecommunication networks represent reliable ambient energy that can be harvested as they are ubiquitous in urban and suburban areas. The state-of-the-art in RF EH for wearable biomedical sensors specifically targeting the global system of mobile 900/1800 cellular and 700 MHz digital terrestrial television networks as ambient RF energy sources are showcased. Furthermore, guidelines for the choice of the number of stages for the RF energy harvester are presented, depending on the requirements from the embedded system to power supply, which is useful for other researchers that work in the same area. The present authors' recent advances towards the development of an efficient RF energy harvester and storing system are presented and thoroughly discussed too.

2015-02Journal article

Open access