Communications meets copula modeling: Non-standard dependence features in wireless fading channels

Abstract

Copula models have started to be explored in wireless communications, however to date the properties they offer have not been proven or verified on real data experiments. In this paper we provide the first real evidence that the features they offer will provide beneficial modeling capabilities in wireless channel models, which are not just theoretically justified but practically observed. We demonstrate how to utilize the concept of copula modeling in wireless communications. In particular we show for the first time the existence of non-standard dependence features between multiple frequency bands in wireless fading channels using real observations. Classical approaches based on second order statistics are not able to detect such tail dependence features. To model this important feature we fit a mixture copula model based on members of the Archimedean family of copulas to real channel measurements. The channel measurements used in this work have been performed at the Barajas airport in Spain, in conjunction with the development of the AeroMACS system for airport surface communications. We give a physical interpretation on this phenomenon and discuss its impact on the design of wireless communication systems with regard to resource allocations.