The answer to the bandwidth shortage could be cost-effective cell splitting, complementing the existing wide area base stations with a large number of smaller base stations.

FORBES: The Solution For The Bandwidth Shortage? Better Silicon Devices

In the short run, carriers have taken steps to manage spectrum more efficiently by splitting cell sites, offloading traffic onto local WiFi connections and upgrading back-haul networks.

FORBES: Attention Congress: We Need More Phone Spectrum, And Soon

To measure the refractive indices of different parts of a cell they use a technique called interferometry, which involves splitting a beam of light in two.

ECONOMIST: Microscopy