Licensed Countrywide Full-Spectrum Allocation: A New Paradigm for Millimeter-Wave Mobile Systems in 5G/6G Era

The traditional static allocation of a portion of the licensed spectrum specified for a country to a mobile network operator (MNO) is no longer sufficient to address the required spectrum demand, as well as efficient to utilize the allocated spectrum. To overcome these constraints, i.e. to increase the spectrum availability and utilization, in this paper, we present a new paradigm for the spectrum allocation called licensed countrywide full-spectrum allocation (LCFSA) to allocate the licensed countrywide full 28 GHz millimeter-wave (mmWave) spectrum to each MNO of a country to operate its small cells per building subject to avoiding co-channel interference (CCI). Since most data is generated indoors, the countrywide full mmWave spectrum allocated to an MNO is considered reusing further to its in-building small cells. CCI avoidance in both the time-domain and frequency-domain is presented along with deducing the conditions for optimality. We derive average capacity, spectral efficiency (SE), energy efficiency (EE), and cost efficiency (CE) for LCFSA, and perform extensive numerical and simulation results and analyses for a country consisting of four MNOs. It is shown that LCFSA with both the time-domain and frequency-domain CCI avoidance schemes provide similar performance improvement in average capacity, SE, EE, and CE by about 296%, 164%, 75%, and 60% respectively for no interfering user equipments (UEs), whereas by about 59.2%, 6.1%, 37.2%, and 0.45% respectively for all interfering UEs with the frequency-domain CCI scheme. Moreover, it is found that the improvement in the above metrics does not change with the spectrum reuse factor (RF) and the number of buildings of small cells per macrocell L, and the impact of interfering UEs can be compensated by adjusting RF. Finally, we show that LCFSA can satisfy the SE and EE requirements for sixth-generation (6G) systems by adjusting either RF or L, or both.