Spectrum and Network Density Management in 5G Ultra-Dense Networks

Recent studies argue that optimizing the utilization of the density of the radio access network plays a crucial role in fully attaining the spectral efficiency of modern ultra-dense networks. This insight implicitly unveils a trade-off between the management of spectrum resource and the network density that offers new angles to systematically optimize the network spectral efficiency. Leveraging this tradeoff, this article proposes a framework for joint management of spectrum and network density in ultra-dense networks where the frequency spectrum and the density of the radio access network are treated as resources to be jointly optimized to improve the network spectral efficiency. The generality of this approach is demonstrated in several scenarios, including spectrum and network density management for network slicing, and spectrum sharing among multiple operators of co-located ultra-dense networks. In the process, we also discuss centralized and distributed architectural solutions for spectrum management where a network operator is granted either exclusive or non-exclusive access to a portion of the shared spectrum band.