FDLoRa: Scaling Downlink Concurrent Transmissions With Full-Duplex LoRa Gateways

Abstract

Unlike traditional data collection applications which primarily rely on uplink transmissions, emerging applications (e.g., device actuation, firmware update, packet reception acknowledgment) increasingly demand robust downlink transmission capabilities. Current LoRaWAN systems struggle to support these applications due to the inherent asymmetry between downlink and uplink capabilities. While uplink transmissions can handle multiple packets simultaneously, downlink transmissions are restricted to a single logical channel at a time, significantly limiting the deployment of applications that require substantial downlink capacity. To address this challenge, FDLoRa introduces an innovative in-band full-duplex LoRa gateway design, featuring novel solutions to mitigate self-interference (i.e., the strong downlink interference to ultra-weak uplink reception). This approach enables full-spectrum in-band downlink transmissions without compromising the reception of weak uplink packets. Building on the capabilities of full-duplex gateways, FDLoRa presents a new downlink framework that supports concurrent downlink transmissions across multiple logical channels of available gateways. Evaluation results show that FDLoRa enhances downlink capacity by 5.7× compared to LoRaWAN in a three-gateway testbed and achieves 2.58× higher downlink concurrency per gateway than the current leading solutions.