The Beijing 2022 Winter Olympics are being held in a "closed-loop" system, where participants and visitors are separated from the public because of Covid-19. It's the perfect environment to push the limits of modern technology and Beijing is showcasing a whole host of innovations, from 5G to robots and from 8K broadcasting to its digital currency, the e-CNY. Peter O'Brien takes us through some of the breakthroughs and controversies surrounding tech at the Games.