Tracing Contacts to Control the COVID-19 Pandemic

Abstract

The control of the COVID-19 pandemic requires a considerable reduction of contacts mostly achieved by imposing movement control up to the level of enforced quarantine. This has lead to a collapse of substantial parts of the economy. Carriers of the disease are infectious roughly 3 days after exposure to the virus. First symptoms occur later or not at all. As a consequence tracing the contacts of people identified as carriers is essential for controlling the pandemic. This tracing must work everywhere, in particular indoors, where people are closest to each other. Furthermore, it should respect people's privacy. The present paper presents a method to enable a thorough traceability with very little risk on privacy. In our opinion, the latter capabilities are necessary to control the pandemic during a future relaunch of our economy.

Identifying the BLE Advertising Channel for Reliable Distance Estimation on Smartphones

“…When the contact duration (which is estimated based on the period of time during which beacons from a particular device are received) is sufficient and/or the estimated distance is small enough, a contact is considered as relevant. Hence, when a person is tested positive for SARS-CoV-2, all relevant contacts can be identified in retrospect by evaluating the smartphone data [1]. Besides contact tracing, distance-or proximity estimation plays a key role in a host of applications, such as indoor navigation or object tracking.…”

“…see [2]. In Equation (1), λ is the wavelength of the signal and G t and G r are the gains of transmitter and receiver, respectively. G t and G r can be obtained by calibrating each smartphone model individually.…”

“…2) The path loss of a signal depends on the channel/frequency on which the signal is transmitted, see Equation (1). This effect can also be cancelled easily when the channel on which a packet was received is known.…”