  We address the problem of resource allocation (RA) in a cognitive radio (CR)
communication system with multiple secondary operators sharing spectrum with an
incumbent primary operator. The key challenge of the RA problem is the
inter-operator coordination arising in the optimization problem so that the
aggregated interference at the primary users (PUs) does not exceed the target
threshold. While this problem is easily solvable if a centralized unit could
access information of all secondary operators, it becomes challenging in a
realistic scenario. In this paper, considering a satellite setting, we
alleviate this problem by proposing two approaches to reduce the information
exchange level among the secondary operators. In the first approach, we
formulate an RA scheme based on a partial information sharing method which
enables distributed optimization across secondary operators. In the second
approach, instead of exchanging secondary users (SUs) information, the
operators only exchange their contributions of the interference-level and RA is
performed locally across secondary operators. These two approaches, for the
first time in this context, provide a trade-off between performance and level
of inter-operator information exchange. Through the numerical simulations, we
explain this trade-off and illustrate the penalty resulting from partial
information exchange.
