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- When backscatter communication meets vehicular networks: boosting crosswalk awarenessPublication . Pereira, Felisberto; Sampaio, Hugo; Chaves, Ricardo; Correia, Ricardo; Luís, Miguel; Sargento, Susana; Jordão, Marina; Almeida, Luís; Senna, Carlos; Oliveira, Arnaldo S. R.; Carvalho, Nuno BorgesThe research of safety applications in vehicular networks has been a popular research topic in an effort to reduce the number of road victims. Advances on vehicular communications are facilitating information sharing through real time communications, critical for the development of driving assistance systems. However, the communication by itself is not enough to reach the most desired target as we need to know which safety-related information should be disseminated. In this work, we bring passive sensors and backscatter communication to the vehicular network world. The idea is to increase the driver (or vehicle) awareness regarding the presence of pedestrians in a crosswalk. Passive sensors and backscatter communication technologies are used for the pedestrians’ detection phase, while the vehicular network is used during the dissemination of the detection information to surrounding vehicles. The proposed solution was validated through end-to-end experimentation, with real hardware and in a real crosswalk with real pedestrians and vehicles, demonstrating its applicability.
- Design of an efficient D-TV energy harvesting system for low-power applicationsPublication . Moura, Tiago; Carvalho, Nuno; Pinho, PedroCollect energy from the surroundings is being biased to power-up devices in order to turn them self-sustainable. On the other hand, the spectrum resultant from the telecommunications tends to progressively increase and becomes wide-reaching, constituting an enormous opportunity to energy harvesting. This work aims to contribute with useful trends into the rectifier design to fulfil energy harvesting purposes. Three rectifiers are designed to collect D-TV spectrum and optimized to operate at low input power conditions. Measurements indicates 63% efficiency at -10.5 dBm input power with the Portuguese D-TV signal.
- High-efficiency D-TV energy harvesting system for low-input powerPublication . Moura, Tiago; Carvalho, Nuno; Pinho, PedroIn this work, a high-efficiency radio-frequency energy-harvesting system that takes use of the Portuguese Digital Television signal (750-758 MHz) to obtain DC power is proposed. To be useful, it is optimized to operate at low-power conditions. For the rectifier, three different solutions are presented: a single-series diode, a single-shunt diode, and a voltage-doubler configuration. The efficiency is similar for the three rectifiers - about 54% with a sine-wave excitation and -10.5 dBm of input power. Field measurements with the voltage-doubler have shown 63% efficiency for the same input power.