Beyond Broadcasting: Revisiting FM Frequency-band for Providing Connectivity to Next Billion Devices

Wireless communication remains a significant power-consuming task for embedded systems. When exacerbated by increased wireless contention, it results in frequent re-transmissions and, consequently, rapid battery depletion in wireless embedded systems. We introduce TunnelRadio, which is our ongoing effort to design low-power radio transmitters that achieve significant energy efficiency compared to commodity radio transceivers. TunnelRadio leverages tunnel diodes to design energy-efficient oscillators that generate a carrier signal and mix it with a baseband or audio signal, operating at microwatts of power consumption. Specifically, we design TunnelRadio to broadcast signals in the FM broadcasting band. In this work, we demonstrate that TunnelRadio can broadcast an audio signal up to a distance of 24 meters while consuming fewer than 150 microwatts. Additionally, we showcase the transmitter's capability to transmit complex baseband signals, such as those modulated with chirps. Our preliminary work aims to pave the way towards more widespread use of the FM band, thereby enabling large-scale deployments of wireless embedded systems.