## 5 Performance Evaluation and Comparison
### Performance Evaluation
Rather, the best of performances can be obtained when all small cell UEs of MNO 1 per building can be scheduled 100% of the time, i.e., in all TTIs over any APP. Furthermore, from Figures 9 and 10, LAA provides the best performance of all techniques in terms of spectral and energy efficiencies. This is due to the fact that, in LAA, transceiver 2 operates in the 60 GHz band signal, which is much less affected by the multipath fading effect due to the high possibility of the presence of line-of-sight (LOS) components that causes the signal help experience a good channel gain within a short distance. The average channel gain at 60 GHz in terms of the number of transmitted bits per second per Hz approaches near the maximum value of 4.4 bps/Hz as given by (3). Further, the transceiver 2 can serve traffic in each TTI since the ABS based eICIC technique is not needed for LAA. Furthermore, due to its best spectral efficiency performance, LAA also provides with the best energy efficiency performance, i.e., it spends the lowest amount of energy to transmit information per bit. Unlike the LAA, the performance of LSA depends on a number of factors, including the characteristics of the spectrum band for the transceiver 2, the type of system that shares its spectrum with the concerned MNO, and the considered interference management policy. For example, from Figure 9, since we consider the same spectrum band for the DySP and LSA, both techniques give almost similar spectral efficiency and energy efficiency responses. However, since the DedA technique operates only at a single frequency spectrum band, which is reused to small cells by applying the ABS based eICIC techniques, DedA provides with the minimum amount of spectral efficiency and hence requires the maximum amount energy to transmit one-bit information per second. Figure 10: Performance responses of all the realized spectrum access techniques for an ultra-dense deployment of small cells in multiple buildings (i.e., \(L>1\)): (**a**) The spectral efficiency and (**b**) energy efficiency. Note also that even though StSR technique operates at both transceivers, the performance responses are almost the same as for DedA because of choosing a small percentage of the spectrum of MNO 2 (i.e., 20%), which is rented by MNO 1 to operate its transceiver 2. However, due to the investment in renting spectrums from another MNO, the additional capacity gain is compensated by the rented spectrum. Hence, so long as the amount of rented spectrum from other operators is not large enough, DedA technique is preferable to StSR due to avoiding the cost from the additional spectrum licensing fee and the complexity from the coordination between MNOs. Note that in evaluating the spectral efficiency, we only consider the spectrum that is explicitly owned by an MNO at the cost of paying the licensing fee. Particularly, we avoid considering the spectrum of a different system for MNO 1 in LSA and the unlicensed spectrum in LAA to evaluate the spectral efficiency performance. This is due to the fact that in LSA we assume implicitly that the same amount of spectrum of MNO 1 is shared by the MNO 2 each other, whereas, in LAA, the spectrum is unlicensed such that there is no cost for licensing the additional spectrum to operate the transceiver 2.