The MauMe network - A LoRa multi-hop collaborative protocol and low-cost implementation example

Abstract

Low-cost low-power long-distance LoRa radio devices recently made available on the market allow the emerging of a new generation of networking paradigms on the Internet of Things. While the LoRaWan offers an efficient way of connecting LoRa end-point devices to the internet, LoRaWan nodes do not act as peers, but rather as terminals connected to gateways. As such, the current state of the art does not offer a public protocol for easily taking advantage of the fact that individuals and professionals wishing to aggregate data using LoRa devices are likely to run each a “base-node” on a continuous basis. Such permanently-powered base-nodes could potentially offer an increased cumulated area coverage to other nodes if they would behave as relays. In the present study, an Epidemic Delay Tolerant Network messaging protocol is proposed, which allows multi-hops between peer LoRa relay-nodes through a raw-LoRa controlled-flooding approach. This protocol has been implemented on low-cost LoRa-chip-equipped microcontrollers in the form of an open-source library acting as a network transport-layer. The design analysis concluded that MauMe is better suited for networks with reduced connectivity (≤ 9), and that a 4-connectivity redundant network could allow each user to send several tens of messages several tens of hops away. The proposed approach was tested on three different LoRa network topologies, and the totality of the packets and acknowledgments reached their destination. Furthermore, the network's activity ceased after delivery, confirming the ability of the protocol to return the network to rest after the flooding. The proposed library also offers to users a free emergency-messaging system implemented as an http server embedded in each node and accessible via Wi-fi. End-users can readily use our solution to easily deploy a network of sensors at a much lower cost than when using multiple gateways. The MauMe protocol is a first step towards the creation of collaborative and application-friendly extended-range LoRa-peers networks, and is intended for use in remote regions with scattered housings such as in the islands and atolls of Polynesia.