Use it or Share it: Unlocking the Vast Wasteland of Fallow Spectrum
35 Pages Posted: 26 Jan 2012
Date Written: September 25, 2011
This paper suggests a general approach to authorizing and encouraging the utilization of otherwise wasted spectrum capacity: Use it or share it. The Federal Communication Commission and Obama Administration propose to meet exponential growth in mobile data demand by reallocating 500 MHz over 10 years. But while policymakers are focused almost entirely on auctions, there is a looming limit to the amount of spectrum below 3.7 GHz that can be reallocated for exclusively licensed commercial use. In contrast, there is substantially more unused and underutilized spectrum in Federal and some other bands where it is either not practical to relocate incumbent users or where that will take many years. Longer term, more dynamic sharing of unused or underutilized bands will be essential – a shift that will expand capacity and facilitate multi-band wireless networks characterized by far greater spectrum re-use close to the end user. Both spectrum re-use and backhaul will increasingly be more cost-effective at the edge of the network, closest to end-users and subject to their control (or, more practically speaking, determined on the fly by software in their device). Unused spectrum capacity can be made available more rapidly by developing more explicit band-by-band conditions for opportunistic access on a secondary basis that ensure primary users protection from harmful interference. A variety of “smart radio” technologies (e.g., sensing, dynamic frequency selection, software defined radios) and spectrum management tools (e.g., geolocation databases) will support dynamic spectrum access and shared use of a far larger number of underutilized bands, each with its own tailored use restrictions to minimize the risk of harmful interference to incumbents. The most promising mechanism for governing conditional access to underutilized bands are the geolocation databases the FCC will soon certify to manage unlicensed use of “white space” channels across the nation’s 210 local TV markets. If a frequency band is not being used at particular locations, time segments, altitudes, or angles of reception, then that currently wasted spectrum capacity could at a minimum be listed in the Database for opportunistic access, subject to whatever power limits, geographic exclusions and other conditions are necessary to avoid harmful interference to primary users or licensees. Device makers and service providers would simply choose from an expanded Database the combination of frequencies most appropriate to their needs. Three categories of spectrum should be prioritized for shared access: (1) FCC-held spectrum; (2) Federal bands that NTIA has determined cannot be cleared within 5 years for reallocation by auction; (3) fallow spectrum on licensed bands that have not been built out in substantial portions of the country. Bands opened for dynamic access can be unlicensed, leased, lightly-licensed or subject to user fees or micro-payments as appropriate.
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