  Data traffic demand in cellular networks has been tremendously growing and
has led to creating congested RF environment. Accordingly, innovative
approaches for spectrum sharing have been proposed and implemented to
accommodate several systems within the same frequency band. Spectrum sharing
between radar and communication systems is one of the important research and
development areas. In this paper, we present the fundamental spectrum sharing
concepts and technologies, then we provide an updated and comprehensive survey
of spectrum sharing techniques that have been developed to enable some of the
wireless communication systems to coexist in the same band as radar systems.
