Know when to listen: SDN-based protocols for directed IoT networks.

Low-power wireless networks are an integral part of the Internet of Things, composed of resource-constrained devices harvesting ambient information. The appearance of unidirectional links is characteristic of low power wireless networking due to physical effects, device heterogeneity and manufacturing imperfections. Despite the prevalence of unidirectional links, most routing and radio duty cycling protocols designed for these networks do not account for such links. We provide unidirectional-link-capable protocols and study the impact of using such links on network performance indicators, such as the data delivery ratio, delay and energy consumption. Our protocols are flexible and flooding-free, leveraging centralized knowledge provided by the Software-Defined Networking paradigm. Our experiments reveal that, while unidirectional links must be detected, using them for routing enhances network performance only if the unidirectional links are long.