Multi-homed wireless networking for intermittently-powered embedded systems

Battery-free devices harvest the energy required for their operation from the environment. In order to be resilient against power failures, such devices need to persist their state before failing, which includes the state of their networking stack. If this stack is implemented in a transactional way, persisting its state is straightforward. The transactions are amenable to worst-case analysis, and are only started when a sufficient amount of energy is available. This may cause cheap transactions to be preferred over energy-intensive ones, particularly physical transmission, resulting in missed packet transmission deadlines.Embedded devices often feature multiple communication interfaces, differing in terms of energy requirements and latency. In this work, we extend a transactional network stack to exploit multiple interfaces, in order to satisfy both energy requirements as well as transmission deadlines on intermittently-powered devices. We evaluate this stack on a Raspberry Pi Pico 2W equipped with a Wi-Fi and BLE interface, using measured energy consumption combined with a simulated charging model. We also pave the way towards static analysis on this platform.