Florin Hutu

A new wake-up radio architecture for wireless sensor networks

The last decades have been really hungry in new ways to reduce energy consumption. That is especially true when talking about wireless sensor networks in general and home multimedia networks in particular, since electrical energy consumption is the bottleneck of the network. One of the most energy-consuming functional block of an equipment is the radio front end, and methods to switch it off during the time intervals where it is not active must be implemented. This paper proposes a wake-up radio circuit which is capable of both addressing and waking up not only a more efficient but also more energy-consuming radio front end. By using a frequency footprint to differentiate each sensor, awaking all the sensors except for the one of interest is avoided. The particularity of the proposed wake-up receiver is that the decision is taken in the radio-frequency part and no baseband treatment is needed.

Wake-up radio architecture for home wireless networks

In this paper it is presented and validated by simulation a wake-up radio receiver (WuRx), allowing to both addressing and wake-up a main radio, with best performance but more energy consuming. The main goal is to reduce the total energy consumption of a home multimedia network by switching off the data module of each equipment during the periods when it is not used. The wake-up receiver is designed to be able to detect a wake-up signal which has a frequency signature and so, it is avoided to activate all data interfaces but only the one of interest.

SDR for SRD: ADC specifications for reconfigurable gateways in urban sensor networks

Short Range Devices (SRD) are increasingly employed in urban sensor networks using different communication protocols. That becomes a key problem in the gateway design, since its cost and energy consumption increase with the number of implemented technologies. This cost and energy can be reduced by using a reconfigurable gateway to perform the biggest part of signal processing digitally, as it is done in Software-Defined Radio (SDR). As several received signals should be simultaneously digitized, Analog-to-Digital Converter (ADC) must be able to treat the whole frequency band used by SRD, with a high enough resolution to properly demodulate the signals. This paper describes what the ADCs constraints are and how to dimension an ADC in SDR for SRD. An example based on the SmartSantander deployment shows that an ADC resolution of 21 bits is required to properly demodulate the data.

Digital estimation and compensation of I/Q imbalance for full-duplex dual-band OFDM radio

With the increasing demand of wireless applications, current radio transceivers are challenged by the requirement of high data rate and high flexibility. Full-Duplex Dual-Band OFDM radio transceiver is a very promising radio technique to approach this goal. However, the mutual undesirable signal leakages due to the I/Q imbalance in the Full-Duplex Dual-Band RF front-end lead to a significant performance degradation in the radio link. In this paper, a practical and suitable digital I/Q imbalance estimation and compensation method for mitigating the I/Q imbalance in this flexible radio transceivers is developed and evaluated. The developed I/Q imbalance estimation method is based on the character of the frequency-flat-fading of the self-interference channel. The ADS-Matlab co-simulation results show that the developed digital compensation method can significantly reduce the impact of the I/Q imbalance on the Full-Duplex Dual-Band OFDM radio receivers.

Enhancement optimized MAC protocol for medical applications

Growth of elderly population induces the increasing demands for high-quality healthcare services, wireless body area networks (WBANs) has emerged as a promising solution for monitoring of patients vital life signs parameters. Reliability and extending the lifetime are considered amongst the important and challenging issues in WBANs. The standard IEEE 802.15.4 is considered as the most used MAC protocol for medical sensor body area networks, owing to its low-power, low data rate and low-cost features. In this paper, we propose an enhancement optimized MAC protocol based on IEEE 802.15.4 dubbed EOMAC. The proposed protocol aims to enhance the reliability and to prolong the lifetime of the network, by reducing energy consumption.

Time-Varying Delay Passivity Analysis in 4 GHz Antennas Array Design

In this paper, a new approach for synchronization of dynamical networks with time-delays is proposed. It is based on stability theory of coupled time-delayed dynamical systems. Some new criteria for stability analysis which ensure the synchronization of the networks are analytically derived. Conditions for synchronization, in the form of Linear Matrix Inequality, are established. They use the Lyapunov and Krasovskii stability theories. In this approach, parameter uncertainties are introduced in the network model. Numerical simulations show the efficiency of the proposed synchronization analysis. A network of 4-GHz smart antenna array is used and analyzed in some details. This array provides a control of the direction of the radiation pattern.

Experimental validation of a wake-up radio architecture

This paper presents an experimental validation of a wake-up radio receiver (WuRx), allowing to both address and wake-up a main radio front-end, which has best performance but more energy consumption. The main goal is to reduce the total energy consumption of communicating objects by switching off the data transceiver module of each equipment during the periods when it is not used. The wake-up receiver is designed to be able to detect a wake-up signal which has a particular frequency signature and so, avoiding activating all main radio front-ends but only the one of interest. Moreover, the identification is performed in RF domain via passive circuitry and no base-band processing is needed.

Récepteur de type “wake-up” radio à identification par empreinte fréquentielle

The Internet of Things (IoT) is described as the industrial revolution of the early 21th century. Innumerable communicating objects will be deployed in the coming years and one of the consequences will be the exponential growth of the IoT energy footprint. The use of ultra-low energy radio receivers (wake-up radios) is one of the envisaged solutions to reduce the energy consumption. By using such kind of receivers, the radio transceiver which consumes the most greedy part of energy of communicating objects, will be power supplied only during the active periods. In the scientific literature, the use of on-off keying (OOK) modulation together with envelope detector based radio part and a microcontroller unit is highlighted for the wake-up radios. The authors of this paper proposed an original approach consisting in a quasi-passive wake-up radio where the identification is done by the means of passive filters and the use of orthogonal frequency division multiplexing (OFDM) signal. This approach is validated through measurements on a functional prototype and, in this paper, the receiver sensitivity and the communication range are given.

Digital I/Q imbalance correction for full-duplex dual-band OFDM radio transceivers

This paper presents a Full-Duplex Dual-Band (FDDB) OFDM radio architecture that enables the radio transceiver to be more flexible and provides a viable radio link capacity gain. A simple but practical I/Q imbalance estimation and compensation method, based on the frequency-flat-fading behavior of the self-interference channel, is proposed. The performance of the proposed I/Q imbalance compensation method is evaluated by system level simulations conducted with ADS and Matlab. The co-simulation results show that the proposed radio transceiver could potentially increase the physical layer transmission rate by four times compared to the conventional radio link at the cost of tolerable loss of BER performance. The I/Q imbalance compensation method can effectively compensate both high and low I/Q imbalance without the problem of algorithm convergence.

A parallel unbalanced digitization architecture to reduce the dynamic range of multiple signals

The technologies employed in urban sensor networks are permanently evolving, and thus the gateways of these networks have to be regularly upgraded. The existing method to do so is to stack-up receivers dedicated to one communication protocol. However, this implies to have to replace the gateway every time a new protocol is added to the network. A more practical way to do this is to perform a digitization of the full band and to perform digitally the signal processing, as done in Software-Defined Radio (SDR).