Capacity Analysis for Multiple Antennas Network in Spectrum Sharing System

Abstract

In this paper, we consider a system where a secondary base station (SBS) with K antennas utilizes the licensed spectrum of a single primary user (PU) to send information to N secondary users (SUs). Each SU and PU is equipped with one antenna, respectively. The SBS selects only one antenna out of the K antennas by using maximum signal power to leak interference power ratio strategy (SLIR). Using asymptotic analysis, we first derive the average capacity of the best user scheme, with perfect channel state information from the SBS to the PU (interference CSI) available at the SBS. Due to limited cooperation between the SBS and the PU, perfect interference CSI is not always available at the SBS. Then, we characterize their capacity loss in the case that perfect interference CSI is not always available at the SBS.