Co-Primary Licensed Spectrum Sharing Techniques for In-building Small Cells in 5G Era

In this paper, we propose two co-primary spectrum sharing (CoPSS) techniques, namely dynamic spectrum pooling (DySP) and static spectrum renting (StSR), for small cells deployed in 3-dimensional (3D) buildings for the fifth-generation (5G) mobile networks. We consider a scenario of two mobile network operators (MNOs) where the whole spectrum of one MNO is considered sharing only with small cells per building of the other MNO by exploiting the external wall penetration loss of each building. More specifically, in DySP, unlike spectrum pooling, only the licensed spectrum of one MNO can be shared deterministically with small cells within each building of the other MNO and vice versa such that the network capacity demand of an MNO can be scaled easily. Likewise, in StSR, unlike mutual renting, a certain portion of the spectrum of one MNO is rented exclusively for a certain time period so that the rented spectrum can solely be used to small cells within each building of the buyer MNO without any pre-emptive priority of the owner MNO. Hence, the proposed CoPSS techniques can overcome the limitations of the generic CoPSS techniques, i.e. the spectrum pooling and mutual renting techniques. We derive average capacity, spectral efficiency, and energy efficiency metrics for both techniques and extensive performance evaluation is carried out to show the relative outperformance of the DySP in terms of spectral and energy efficiencies over the StSR. Finally, we show that the proposed CoPSS techniques can meet the requirements of spectral and energy efficiencies for 5G mobile networks.