While most operators and regulators have virtually given up on the TV white spaces (TVWS) spectrum as a way to expand mobile capacity cheaply – after a rush of excitement more than a decade ago – Microsoft has kept the flame alive with its US-based Airband initiative. Launched in 2017, this is a five-year project to bring affordable broadband to underserved rural areas, mainly using TVWS spectrum – the unused spaces in the sub-GHz broadcast bands. The size and number of these spaces vary depending how many broadcasters are active in an area, and what services they offer, which is one reason why the idea of using the gaps for wireless broadband fell flat in many countries. But in the…