Browsing by Author "Pham, Congduc"

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    A 2-hop LoRa Approach Based on Smart and Transparent Relay-Device
    (Springer Nature, Switzerland, 2019) Diop, Mamour; Pham, Congduc; Thiare, Ousmane
    LoRa is designed for long-range communication where devices are directly connected to the gateway, which removes typically the need of constructing and maintaining a complex multi-hop network. Nonetheless, even with the advantage of penetration of walls, the range may not sometimes be sufficient. This article describes a 2-hop LoRa approach to reduce both packet losses and transmission cost. To that aim, we introduce a smart, transparent and battery-operated relay-devicethat can be added after a deployment campaign to seamlessly provide an extra hop between the remote devices and the gateway. Field tests were conducted to assess relays’ ability to automatically synchronize to the network without advertising their presence.
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    Outdoor Localization and Distance Estimation Based on Dynamic RSSI Measurements in LoRa Networks: Application to Cattle Rustling Prevention
    (Research gate, 2019) Dieng, Ousmane; Pham, Congduc; Thiare, Ousmane
    In this paper, we propose a RSSI-based distance estimation scheme for localization of cattle collars communicating with long-range LoRa radios. Cattle localization is designed to prevent theft in livestock. The proposed solution decreases the cost of cattle localization by minimizing the number of collars with GPS and allows accurate localization of collars without GPS. We propose a RSSI-based distance estimation using real time adjustment of RSSI-distance mapping taking advantage of communication between collar nodes and gateway. Log-distance path-loss model is also used as rescue when the map does not provide accurate correspondence. Experimentation results show the validity of the approach with highly accurate localization of non-GPS collars.