COVID-19 Density Tracker

Introduction

With the summer weather in full effect and businesses gradually reopening, many are coming out of quarantine to catch up with friends at the park, enjoy the remainder of patio season, or indulge in some retail therapy at the mall. While most locations have physical distancing protocols and layouts in place, they are not always abided by. With public areas becoming occupied towards once-normal capacities, many do not (or perhaps cannot) maintain adequate distance from others to minimize the spread of COVID-19. Amongst other examples, Florida recently suffered a spike of 25 000 new cases within five days (Hodgson, 2020). This was explained by failure to social distance at bars, restaurants, and beaches. While we understand the desire to return to normal, we think that a more cautious new normal should be established to mitigate potential subsequent spikes. We hope to contribute to this new normal by aiding your efforts to physical distance. We have both driven to a grocery store only to find that there is a long line or that upon entering the store, it is quite full with insufficient distancing. Not to mention the visits to our local lakefront only to turn right around as hundreds of others shared our optimistic plan. To combat this, we created a system that informs you of how busy a destination is so that you can plan accordingly - perhaps you will still go but be better prepared with protective gear or find a less populated alternative from the get-go. Either way, we hope to protect communities by making trips out of the house safer and encourage users to be mindful of their destinations to avoid risk. While our density tracker was designed with the intention of public use, it may also have epidemiological application as it can help to track hotspots.

How It Works

Our system tracks wifi activity within a specified area (ie. a shopping mall, various vicinities of a park) to determine how many active devices are present and thereby, garnering accurate head counts. Our density tracker is similar to that of Google Map’s “popular times” feature. However, it is differentiated by its ability to compare multiple locations at once and provide numerical data as opposed to arbitrary histograms. Furthermore, our system would encompass more devices as Google Maps only tracks users who have opted into the app’s location storage feature.

The density tracker utilizes an EPS8266 to analyze nearby packets for probe requests. Probe requests are Wifi data frames that are emitted from mobile devices roughly 30 - 60 seconds apart to check for wifi access points. We can use these probe requests to calculate precisely how many active devices are present thus assuming how many people are present.

The density tracker can be deployed using one of two options: To scan devices only connected to a wifi network, or to scan both devices connected to a network and those that are not. Option 1 identifies the presence of a device by its unique identifier (MAC address). Option 2 monitors probe request frequency within specified time frames. MAC addresses cannot be used in this case as most modern smartphones randomize their MAC address for privacy purposes. Both options would provide real time data through instantaneous reports with a refresh rate of one minute. This rate can be modified to be slower or faster.

We had originally designed our tracker around the nRF52840 board to track bluetooth activity. We ultimately found our new methodology to provide more reliable detection as wifi activity is more abundant than bluetooth. The nRF52840 board would be beneficial for future iterations that allow communication between multiple density trackers for wider location coverage (ie. shopping malls)

Set Up

Upload the code to an ESP8266 wire according to the diagram. On start up, 'black list mode' should appear on the LCD with a count down. The black list mode is used to exclude devices from being considered as active. Devices connected to a network can only be blacklisted. An application for this mode is if you want to exclude office devices (ie. wifi printers, desktops, security cameras) from being considered. To enter blacklist mode press the button and a counter will appear with how many devices have been blacklisted. Press the button again to enter scanning mode (scanning active devices).

At this point, data will either be sent to the LCD or a different device depending on what option is selected.

Conclusion

Should the project be implemented, a density tracker would be placed at designated areas and the user will be able to access this data through our website which we are developing for release in August 2020. Planning is an important step in protecting oneself against COVID-19. We hope to inform users of crowded locations, which carry higher risk of infection, so they can plan trips accordingly and avoid compromising physical distancing.