Large-scale antenna technology is a key technology for the fifth-generation mobile
communication (5G) system to improve capacity and spectrum utilization; meanwhile,
cognitive radio (CR) can vastly improve the utilization of unexploited spectrum resources.
This paper employs three CR base stations to realize spectrum sharing in full space, where
three CR base stations are placed at neighboring walls of a cell and distinguish CRs in the
cell by their angular information. To reduce pilot contamination and overhead emerged …

In this paper, we introduce a new spatial spectrum-sharing strategy for massive multiple-
input multiple-output (MIMO) cognitive radio (CR) systems. Different from the conventional
MIMO CR system, CR terminals can be discriminated by their angular information with the
help of high spatial resolution of massive antennas at CR base station (CBS). Moreover, the
discrete Fourier transform can be applied to efficiently obtain such angular information
thanks to the massive antennas, again. We then formulate a 2-D spatial basis expansion …