Spectrum always is valuable because it provides the foundation for firms and business models. That is as true for new shared spectrum capabilities as for traditional Wi-Fi, mobile service provider, TV broadcast and satellite broadcast businesses.

So it will come as no surprise that advocates of shared spectrum likely have different assessments of the value. App providers probably see nothing but upside. Mobile service providers probably see both advantages and disadvantages.

The U.S. National Telecommunications and Information Administration is looking at ways to enable spectrum sharing between government and commercial users in the 3.5 GHz band, hopefully freeing up as much as 500 MHz for shared access, eventually.

At the moment, the U.S. National Telecommunications and Information Administration is working on a plan that would make about 100 megahertz of spectrum available for shared small cell use in the 3.5 GHz band currently used primarily for military radar systems.

NTIA also is evaluating additional unlicensed use in the 5 GHz band.

The plan has not been universally well received. Traditional telecom, cable TV and satellite firms prefer the exclusive licensee approach, for reasons of quality of service control, and, some would say, for reasons of promoting communications spectrum scarcity.

Others, including many application providers, prefer unlicensed and shared access because that lowers the cost of doing business.

Some have noted that signal propagation issues in the 3.5-GHz and other similar bands would likely mean that shared spectrum is most helpful in urban areas, where small cells are practical.

But that might suit some mobile service providers just fine. Illiad’s Free Mobile relies on Wi-Fi access where it can, as a way of reducing the cost of sourcing capacity from other mobile operators. Republic Wireless and Scratch Wireless do the same.

Virtually everybody agrees that licensed and unlicensed, exclusive and shared spectrum approaches will coexist. But dramatically different business models can be built along that continuum.

What is good for app providers might not be so good for ISPs, and vice versa. But shared spectrum provides one key tool for efficiently using available communications spectrum without costly efforts to move existing users.