Accelerating Update Broadcasts Over LoRaWAN Downlink via D2D Cooperation

TL;DR

This work tackles slow update broadcasts in LoRaWAN by introducing a device-to-device (D2D) cooperative mechanism that allows updated end devices to broadcast a small number of coded fragments to neighboring devices. The gateway continues to multicast coded fragments using rateless coding, while D2D transmissions accelerate completion for unfinished peers, all without additional infrastructure or server signaling. Through adaptive D2D framing, windowing, and batched rateless coding, the approach yields dramatic reductions in update completion time and device energy usage, particularly in dense networks, while maintaining duty-cycle compliance. The results demonstrate practical improvements for critical security updates and enable more efficient edge intelligence in large-scale IoT deployments.

Abstract

Broadcast distribution of updates (e.g., security patches, machine learning models) from a server to end devices (EDs) is a critical requirement in the Internet of Things (IoT). In this paper, we consider the problem of reliable over-the-air broadcast of updates in Long Range Wide Area Networks (LoRaWANs). Existing broadcast techniques for LoRaWANs suffer from long delivery delays due to low data rates and duty-cycle constraints. We address this problem by proposing a device-level cooperative mechanism, in which updated EDs broadcast a few update fragments to accelerate delivery to their neighbors. We demonstrate large reductions in the delivery time compared to conventional methods. For instance, in a 400-node network spanning 1 km radius and operating at 1% duty-cycle, the proposed scheme reduces the time required to deliver a 10 kilobyte update to an ED at the network's edge from 42 hours to 45 minutes. The proposed solution thus provides a pathway toward improved security and efficient realization of edge intelligence in LoRaWAN IoT.

Figures (6)

• Figure 1: Representative model of a LoRaWAN in which a subset of the EDs require a firmware update. The update recipients are shown in red. The gateway multicasts the update frames produced by the firmware update server.
• Figure 2: Illustration of downlink (DL) and D2D transmission schedules. Each block represents a ping slot of duration $T_p$. The schedule is illustrated for the case in which one superslot (SS) for both DL and D2D links is composed of two ping slots ($G_p \!=\! 2$, $E_p \!=\! 2$), one D2D window comprises 3 D2D superslots ($S_\mathrm{D2D} \!=\! 3$), and 15 ping slots must elapse between the starts of two consecutive DL frames ($W_p \!=\! 15$) to satisfy duty-cycle restrictions.
• Figure 3: Impact of node distance.
• Figure 4: Impact of recipient count ($N_{\mathrm{ED}}$) and maximum permitted number of superslots per D2D window ($S^*$) on the performance of a device at the cell edge.
• Figure 5: Impact of the SF used on D2D links.