Smartphones reconditionnés comme passerelles maillées en milieu forestier : Évaluation expérimentale et par simulation d’une solution BLE Coded PHY pour le système Silvanet

Details

Supervisors

Bol, David ; Louveaux, Jérôme

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil électricien, à finalité spécialisée

Abstract

enWildfire detection systems based on distributed sensor networks can provide earlier alerts than satellite- or camera-based approaches, but their dedicated infrastructure entails economic and environmental costs. This thesis investigates whether refurbished smartphones could replace part of the mesh-gateway layer of DRYAD’s Silvanet system. A comparative review of LoRaWAN, Bluetooth, Wi-Fi, Wi-Fi HaLow, LTE/5G and cross-technology solutions identifies Bluetooth 5 LE Coded PHY as the most practical native radio interface for direct smartphone-to-smartphone communication. The link is first modeled through a link budget accounting for free-space propagation, vegetation attenuation and receiver noise. Experiments performed with two Google Pixel 6 smartphones then characterize the angular dependence and maximum communication range of LE 2M, LE 1M and LE Coded PHY using the S=2 and S=8 coding schemes. With S=8, a maximum maintained range of 475 m was measured in an open environment and 240 m in a sparsely vegetated forest. These experimental ranges were subsequently introduced into a coverage simulator representing a hexagonal forest with a radius of 3 km and containing 259 wildfire sensors. Complete geometric coverage required 133 smartphone relays when using the open-environment range and 505 relays when using the forest range. The required number of nodes was found to increase approximately with the inverse square of the radio range. The results demonstrate that LE Coded PHY can provide useful long-range local links between smartphones. However, directly replacing the dedicated Silvanet mesh gateways with smartphones communicating exclusively through BLE is not realistic in the studied configuration, as the limited range imposes an excessive relay density. Refurbished smartphones therefore appear more suitable for local or hybrid roles, provided that energy autonomy, multi-hop routing and the interface with the existing LoRa sensors are addressed.