  This work proposes a novel location-based multi-group multicast framework
which is termed as non-orthogonal multiple access (NOMA) assisted multi-region
geocast. This novel spectrum sharing framework exploits the NOMA technology to
realize the simultaneous delivery of different messages to different user
groups characterized by different geographical locations. The essence of the
proposed framework is that the geographical information of user groups unites
NOMA and multi-group multicast to enhance the spectral efficiency (SE) and the
energy efficiency (EE) of wireless transmissions. Specifically, we investigate
the downlink beamforming design of the proposed framework in multiple-input
single-output (MISO) settings. The decoding strategy for NOMA is designed and
guaranteed by users' geographical information and required quality of service
(QoS). The majorization and minimization (MM) algorithm is exploited to solve
the non-convex and intractable problems therein. Comprehensive numerical
experiments are further provided to show that NOMA holds tremendous promise but
also limitations in terms of SE and EE, compared with spatial division multiple
access (SDMA) and orthogonal multiple access (OMA).
