More spectrum and more efficient use of existing spectrum is essentially the choice — or the combination of approaches — that the government and carriers must explore as they face an onslaught of demand driven by mobile devices running an increasing amount of data over legacy 2G and 3G infrastructure and emerging LTE networks.
There is lots of creative work going on, especially on the efficiency side of the equation. Ars Technica has a long and interesting article about the Federal Communications Commission’s adoption of a plan devised by the President’s Council of Advisors on Science and Technology (PCAST).
The concept — which also is under consideration in Europe — is that a lot of spectrum held by the government sits idle most of the time. If that can be shared with carriers, it would go a long way toward stretching the spectral soup. The initial FCC plan will try this sharing on 100 MHz in the 3.5 GHz band. The goal is to share across the 1,000 MHz of spectrum between 2700MHz and 3700MHz, the story says.
During the past few years, one of the main initiatives toward more efficient use of spectrum has been white space. The two approaches are similar and have a similar need. In both, the challenge is that the same spectrum is not available in all places at all times. Thus, the telecommunications industry had to come up with technology that will identify what can be used and what is off limits at any point in time.
There are two approaches to agile use of spectrum. They are explained in the Ars Technica piece, which was written by Jon Brodkin. In one, the radio is smart enough to find out on its own whether the spectrum is free at a particular moment. The other relies on databases, which provide go/no-go instructions to the radio. There are ongoing regulatory proceedings on white space. TV Technology reports that the White Space Alliance has filed a petition in advance of an open meeting at the end of the month:
The filing’s main purpose is to encourage the FCC to allow “cognitive radios” that would be able to sense whether or not a channel was being used and then allow use of that channel if it would not cause interference with a licensed service. Spectrum sensing was part of the original white space devices plan, but when testing showed multiple problems with this approach, the FCC and most device manufacturers turned to geolocation.
Spectrum sharing and white space are closely related but aren’t precisely the same thing. They do, however, rest on the same basic premise: It is possible to gain great efficiencies by using spectrum for a higher percentage of the time. Sophisticated technology must be developed to do this efficiently and safely. With two initiatives apparently sharing the technology need, it is likely that great strides will be made quickly.
