On Application and Evaluation of Millimeter-Wave Spectrum Sharing, Trading and Reusing for Small Cells Toward Spectral and Energy Efficiencies of 6G

In this paper, we present techniques for sharing, trading, and reusing the licensed 28 GHz millimeter-wave (mmWave) spectrum using in-building small cells to achieve high capacity, spectral efficiency (SE), and energy efficiency (EE) for next-generation mobile networks. In this regard, we assume that each mobile network operator (MNO) of a country is statically allocated to an equal amount of 28 GHz licensed spectrum to operate its in-building small cells. We describe each technique and present its mathematical model for an MNO. We then derive system-level average capacity, SE, and EE metrics and carry out extensive simulation and numerical results and analyses when employing each of these techniques individually, as well as jointly, to small cells per building of the MNO. It is shown that spectrum reusing has a substantial impact on the average capacity, SE, and EE performances as compared to spectrum sharing and spectrum trading techniques due to reusing flexibly the mmWave spectrum of the MNO itself to it small cells per building. Moreover, employing all three techniques jointly to small cells provides the best performance of all techniques each employing individually. Finally, it is shown that each of the three techniques employing either individually or jointly can achieve the expected SE and EE requirements for sixth-generation (6G) mobile networks.