Spectrum sharing between small cells and satellites: Opportunities and challenges

Spectrum sharing between heterogeneous systems - such as cellular systems, radars, and satellites - is an emerging area of research as it promises to solve the looming spectrum congestion problem. Spectrum regulators and technical specification bodies are contemplating over the idea of allowing commercial wireless systems to be deployed in satellite bands on a sharing basis. In the United States, the Federal Communications Commission (FCC) has proposed to deploy small cells in the 3.5 GHz satellite band. In this paper, we consider deployment of small cells in satellite bands and address opportunities and challenges that are associated with such a deployment. We focus on the conventional and extended C-band fixed satellite service (FSS) receiving earth stations. We show that small cell operation can result in out-of-band emission and low noise amplifier (LNA) saturation issues for FSS systems. Exclusion zones are required to protect FSS systems. We show that exclusion zones are quite larger when small cells are deployed outdoors as compared to the case when small cells are deployed indoors. Therefore, we propose that small cells should be deployed indoors for the scenarios where FSS systems are geographically colocated. This results in maximum utilization of small cell technology and minimum exclusion zones required to protect FSS receiving earth stations.