Non-Orthogonal Multiple Access Assisted Multi-Region Geocast

This paper proposes a novel location-based multi-group multicast framework, which is termed 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 settings. The decoding strategy for NOMA is designed and guaranteed by users' geographical information and required quality of service. The majorization and minimization 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 and orthogonal multiple access.