Braidio: An Integrated Active-Passive Radio for Mobile Devices with Asymmetric Energy Budgets

Pan Hu, Pengyu Zhang, Mohammad Rostami, Deepak Ganesan

Abstract: While many radio technologies are available for mobile devices, none of them are designed to deal with asymmetric available energy. Battery capacities of mobile devices vary by up to three orders of magnitude between laptops and wearables, and our inability to deal with such asymmetry has limited the lifetime of constrained portable devices. This paper presents a radically new design for low-power radios --- one that is capable of dynamically splitting the power burden of communication between the transmitter and receiver in proportion to the available energy on the two devices. We achieve this with a novel carrier offload method that dynamically moves carrier generation across end points. While such a design might raise the specter of a high-power, large form-factor radio, we show that this integration can be achieved with no more than a BLE-style active radio augmented with a few additional components. Our design, Braidio is a low-power, tightly integrated, low-cost radio capable of operating as an active and passive transceiver. When these modes operate in an interleaved (braided) manner, the end result is a power-proportional low-power radio that is able to achieve 1:2546 to 3546:1 power consumption ratios between a transmitter and a receiver, all while operating at low power.