Bluetooth Contact Tracing Faces Significant Technical Hurdles
Contact tracing apps rely heavily on Bluetooth signal strength to measure proximity, but real-world variables make accurate distance tracking incredibly difficult.
Bluetooth technology serves as the foundation for new contact tracing apps designed to track potential coronavirus exposure. By measuring the strength of wireless signals between smartphones, these applications attempt to determine if two people spend enough time close together to trigger a contact event. Major tech companies like Google and Apple back this approach because it preserves privacy and utilizes existing low-power hardware found in almost all modern phones.
Despite its theoretical simplicity, relying on Bluetooth signal strength to measure exact distance proves highly complicated in practice. The system uses a metric called received signal strength indicator (RSSI) to guess how far apart two devices are, assuming a strong signal means close proximity and a weak signal means distance. However, accurately answering critical public health questions about exact distance and time required for viral transmission remains a massive technical challenge.
Real-world environments constantly disrupt Bluetooth signals and produce inaccurate data. Everyday obstacles like human bodies, walls, pockets, and other nearby electronic devices interfere with the wireless waves, causing the RSSI readings to fluctuate wildly. Until developers solve these complex signal interference problems, Bluetooth contact tracing apps struggle to reliably differentiate between a dangerous close-contact exposure and a falsely reported risk through a wall.