Rate Enhancement For Distributed Massive Mimo Systems With Underlay Spectrum Sharing

We investigate the achievable rate of a single-cell distributed massive multi-input multi-output (MIMO) system underlaid a licensed primary multi-user co-located Massive MIMO network. We propose an access point (AP) selection procedure and power allocation (PA) method to improve the performance of the secondary network and derive the closed-form sum rate expression for Rayleigh fading channels by considering the effects of pilot contamination, inter-user interference and statistical downlink channel state information (CSI) at secondary users (SUs). Our results reveal that, the joint use of AP selection procedure and PA method significantly improve the achieved sum rate of the SUs while preserving the performance of the primary network.