  Contact tracing with mobile applications is an attractive approach for many
governments and industry initiatives to address the Covid-19 pandemic. However,
many approaches today have severe privacy and security issues, and many of them
also fail to offer a sustainable contact tracing infrastructure due to the
demanding energy consumption. This work makes several contributions towards
overcoming these limitations. First, we propose a privacy-preserving
architecture for contact tracing that leverages a fixed infrastructure of BLE
beacon transmitters. Second, we evaluate the feasibility of adopting
batteryless or energy-harvesting BLE beacons to make this architecture more
sustainable and green. Finally, we identify practical research challenges and
opportunities for academia and industry to advance and realize the proposed
privacy-preserving and sustainable contact tracing architecture.
