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A Harmful Interference Model for Unlicensed Device Operation in Licensed Service Bands

Timothy X Brown
Interdisciplinary Telecommunication Program Electrical and Computer Engineering Department University of Colorado Boulder, CO 80309-0530

Abstract—Recent FCC proceedings have considered thenotion of unlicensed device operation in licensed bands.Licensed users are concerned about harmful interferencewhile unlicensed device manufacturers are concerned thatharmful interference is an imprecise design concept. Thispaper addresses two elements to these concerns. First, itdevelops an explicit model of harmful interference to beincluded in unlicensed device rules. Such a model providesexplicit bounded protection to the licensed user while providingassurances and performance goals to the unlicenseddevice manufacturers. Second, it presents an analytic modelfor assessing harmful interference that not only providesquantitative analysis, but, also provides insight into howfactors such as directional antennas, power control, andlicensed channel avoidance strategies affect the aggregateinterference. Further, it suggests that complex factors suchas unlicensed device modulation schemes can be captured ina simple measurement. These ideas are applied to the noticeof proposed rulemaking on Unlicensed Operation in the TVBroadcast Bands.

Index Terms—harmful interference, unlicensed devices,broadcast service, digital television

Cite: Timothy X Brown, "A Harmful Interference Model for Unlicensed Device Operation in Licensed Service Bands," Journal of Communications, vol. 1, no. 1, pp. 13-25, 2006.