Shared spectrum is a double-edged sword for MNOs. It allows them to increase their capacity and quality of service at lower cost than acquiring more licences, but it also opens them up to competition from other providers. Their ambivalence was first seen in WiFi, but now their own cellular technologies are running in shared spectrum too, and MNOs must act decisively to ensure they monetize that new capacity, not an emerging rival. The stand-off is best seen in the US, which has pioneered work on a new shared spectrum approach – the multi-tiered access scheme in the 3.5 GHz CBRS band – and on MulteFire, which allows LTE to run in unlicensed frequencies without a licensed spectrum host network (unlike…