Availability assessment of secondary usage in aeronautical spectrum

In this paper, we provide a quantitative assessment of the available spectrum for massive indoor broadband secondary access in the 960-1215 MHz band, primarily allocated to the distance measuring equipment (DME) systems. We employ a practical sharing scheme where the secondary users share the DME spectrum via geo-location database and spectrum sensing. Since the DME system performs a safety-of-life functionality, protection from harmful interference becomes extremely critical. A DME channel is considered available in a certain time and location if the secondary users, under the applied sharing scheme, are able to successfully access the channel without violating the primary protection criteria. We analyze the impact of the secondary system parameters and the potential uncertainties in the applied sharing mechanism on the availability in the DME band. Numerical results show that at least 30% of the total DME band (57 MHz out of 190 MHz) can be available for a dense low-power indoor secondary network, even if conservative primary system protection criteria and high levels of uncertainty are considered.