Passive User Co-Existence

One of the cross-cutting research thrusts under consideration is the study of passive use cases involving lightly used bands with a variety of incumbents with potentially very sensitive receivers, e.g., RA, satellite receivers, and other sensors. Spectrum allocation for RA is often done on a shared basis, with the RA service (RAS) given primary and secondary status in the allocation table, depending on the band. While coordination zones have been established to protect RAS from harmful in-band and adjacent-band interference, such zones are conservative, as they mainly rely on the location information of major observatories and not the attributes of the RA measurements. These characteristics include measurement type (e.g., spectral lines, continuum observations, etc.), Doppler shift due to motion of source and observation point, acceptable interference levels, maximum allowed outage during a measurement period, receive-beam direction, anticipated changes in antenna gain (e.g., during the tracking of a celestial object), spatial dependence of multi-site RA measurements, etc. New database-centered techniques will be explored for registering the attributes of scheduled RA measurements and coordinating access to the shared spectrum by active satellite/cellular transmitters, without causing harmful in-band or adjacent-band interference to RA receivers. We also plan to develop a novel mathematical framework for predicting outage probabilities for these incumbents in a wide variety of settings.