IRONWAN: Increasing Reliability of Overlapping Networks in LoRaWAN

LoRaWAN deployments follow an
ad hoc
deployment model that has organically led to overlapping communication networks, sharing the wireless spectrum, and completely unaware of each other. LoRaWAN uses ALOHA-style communication where it is almost impossible to schedule transmission between networks belonging to different owners properly. The inability to schedule overlapping networks will cause internetwork interference, which will increase node-to-gateway message losses and gateway-to-node acknowledgment failures. This problem is likely to get worse as the number of LoRaWAN networks increases. In response to this problem, we propose IRONWAN, a wireless overlay network that shares communication resources without modifications to underlying protocols. It utilizes the broadcast nature of radio communication and enables gateway-to-gateway communication to facilitate the search for failed messages and transmit failed acknowledgments already received and cached in overlapping network’s gateways. IRONWAN uses two novel algorithms: 1) a real-time message interarrival predictor, to highlight when a server has not received an expected uplink message and 2) the interference predictor, to ensure that extra gateway-to-gateway communication does not negatively impact the communication bandwidth. We evaluate IRONWAN on a 1000-node simulator with up to ten gateways and a 10-node testbed with 2-gateways. The results show that IRONWAN can achieve up to 12% higher packet delivery ratio (PDR) and total messages received per node while increasing the minimum PDR by up to 28%. These improvements save up to 50% node’s energy. Finally, we demonstrate that IRONWAN has comparable performance to an optimal solution (wired and centralized) but with 2–32 times lower communication costs. IRONWAN also has up to 14% better PDR when compared to FLIP, a wired-distributed gateway-to-gateway protocol in certain scenarios.