Adaptive co-primary shared access between co-located radio access networks

Inter-operator spectrum sharing is expected to play a key role in fulfilling the predicted spectrum demand for future wireless systems. In this work, we propose an adaptive co - primary shared access scheme between co-located Radio Access Networks (RANs) owned by different operators. In the literature, the main focus is on orthogonal spectrum sharing. In this work, the spectrum is adaptively partitioned into private and non-orthogonally shared frequency sub-bands with the aim of maximizing inter-RAN sum rate. The non-orthogonally shared frequency sub-band is simultaneously used by all the RANs, with inter-RAN interference minimized. A zero-forcing precoder is used to serve the users scheduled in the private frequency sub-band. With the exchange of inter-RAN channel state information, a sparse precoder is used as inter-RAN precoder to serve the users scheduled in the shared frequency sub-band. Using a heuristic algorithm based on user grouping, spectrum partitioning and user scheduling are optimized. Based on simulation results, the proposed adaptive spectrum sharing approach outperforms conventional approaches of orthogonal and full-band non-orthogonal spectrum sharing.