GRAPMAN: Gradual Power Manager for Consistent Throughput of Energy Harvesting Wireless Sensor Nodes

International audienceIn this work, Wireless Sensor Network (WSN) applications that require long-term sustainability are considered. Energy harvesting forms a promising technology to address this challenge, by allowing each node to be entirely powered by energy harvested from its environment. To be sustainable, each node must dynamically adapt its Quality of Service (QoS), regarding the harvested energy using a power management strategy. This strategy is implemented on each node by the Power Manager (PM). In this paper, GRAPMAN (GRAdual Power MANager) is proposed, a novel PM for Energy-Harvesting WSN (EH-WSN) powered by pseudo-periodic energy sources. Unlike most state of the art PMs, GRAPMAN aims to achieve high average throughput while maintaining consistent QoS, i.e. with low fluctuations with respect to time, by looking for the highest throughput that can be supplied by the node over a finite time horizon while remaining sustainable. We show through extensive trace-driven network simulations that GRAPMAN outperforms state of the art PMs in both average throughput and throughput consistency

Guayule cultivation as a sustainable leverage to rehabilitate urban brownfields

Brownfields are a common species of modern urban landscape. Urban brownfields can have various origin (industrial, residential or commercial …) but they often present similar issues: degraded soils (compaction, lack of fertility, pollutants …), limited biodiversity and associated ecosystem services furniture, unwanted species (including humans) and vague future. Producing high value biomasses on these brownfields is a promising leverage to “use” these areas. Cultivating biomasses on urban brownfield will improve soil quality, increase ecosystem services furniture and prevent unwanted species installation. For this purpose, Guayule is a promising crop as it can be economically profitable on small areas (>1ha, Sfeir et al. 2014) and is able to grow on low fertility soils. AgroGuayule project (ADEME-GRAINE cofounding) aims at breaking numerous technical-economical barriers to allow Guayule cultivation on brownfields. Pilot plantations were made across various brownfields to access the feasibility of guayule growing in various conditions. Several scenarios of soil and plant fertilizers are currently tested to estimate their cost-benefice balance. During the talk, we will present the AgroGuayule projects aims and the first results from the pilot plantations and how they can be scale up at a national scale with an ecological engineering and agroecological perspective

Asynchronous MAC Protocol for Spectrum Agility in Wireless Body Area Sensor Networks

International audienceA Wireless Body Area Sensor Network (WBASN) is a special-purpose Wireless Sensor Network (WSN) that supports remote monitoring and entertainment applications. The energy consumption plays an important role in the design of this specific sensor network. Unfortunately, the performance of WBASNs decreases in high interference environments such as the Industrial, Scientific and Medical (ISM) band where wireless spectrums are getting crowded. In this paper, an energy-efficient Medium Access Control (MAC) protocol named C-RICER (Cognitive-Receiver Initiated CyclEd Receiver) is specifically designed for WBASN to cognitively work in high interference environment. C-RICER protocol adapts both transmission power and channel frequency to reduce the interferences and thus, the energy consumption. The protocol is simulated thanks to OMNET++ simulator. Simulation results show that, depending on the interference level, C-RICER is able to outperform the traditional RICER protocol in terms of energy consumption, packet delay, and network throughput

On the performance of distributed space-time coded cooperative relay networks based on inter-relay communications

International audienceA new protocol, called fully distributed space-time coded (FDSTC) protocol having information exchange between relays, is proposed and compared with the conventional distributed space-time coded (DSTC) protocol using non-regenerative relays (NR-relays) and regenerative relays (R-relays). Closed-form error probabilities are derived to verify the simulations. In terms of error performance, the FDSTC protocol gets significant average signal-to-noise ratio (SNR) gains (3.7 dB for NR-relays and 18.1 dB for R-relays). In addition, the impact of the relative distance of relays on the required SNR is reduced up to 70%. The system diversity order using the FDSTC protocol is higher than that using the DSTC protocol (especially, the FDSTC protocol obtains full diversity with NR-relays). As a result, at the same spectral efficiency, FDSTC has better performance in terms of outage probability in high SNR regions. In terms of energy efficiency, the FDSTC protocol is shown to outperform DSTC for long-range transmissions