Our paper Renovating Road Signs for Infrastructure-to-Vehicle Networking: A Visible Light Backscatter Communication and Networking Approach has been accepted to MobiCom! Congrats!
This project was initiated based on PassiveVLC, which applies backscatter communication to visible light (literally a long long time ago). The key idea of this project is kind of incremental. So the use case must be realistic, and the experiment must be thorough. However, it is extremely challenging.
First, PassiveVLC does not work in day time due to strong ambient light (day light is much much more stronger than most of the man-made light source). This limitation forces us to do a better job in evaluation and writing part. Moreover, as we all know, winter is cold, winter night is colder. In that temperature, most of the batteries cannot work normally. So we have to bring a heavy UPS power supply with us, and replace with a charged one every 2 hours.
Second, to put this technique into real use, we must have a decent communication range (~100m). 10x more than PassiveVLC. Thus, we have to scale both our reader and tag up. We were so lucky that Yue Wu could do great AutoCAD design, and both Yue Wu and Purui Wang could do circuit design (these two skills are extremely rare in our CS department.) However, even in this scenario, we still spent tons of efforts to update our hardware and make it work.
Third, we need to show that our system somehow works under severe whether condition. I can still recall that we almost start to travel just for fog day.
Fourth, physical bugs is frustrating. We wrote correct software, but the system could fail due to physical bug in just one second, and it takes tens of minutes (even two hours) to debug.
Fifth, since we are targeting Infrastructure-to-Vehicle scenario, experiments on car speed is critical. To do this experiment, we need to hire a driver, find a road without cars, put the reader on the car, support the tag with a supporting frame, and wish that no wire disconnection (which typically need to be fixed in lab) happens. And it happens two times. Please imagine the frustration that you finally set up all the things after 2 hours working in dark cold winter night, and it suddenly doesn’t work due to physical, and you know you have to go back and fix it.
From 2017 to 2020. After three years, we finally get this work published. Congrats to the hard work of all our team members.