## 3 Simulation Setup and Results under Ideal Assumptions
### Performance with Ideal Assumptions  
In this section, a performance comparison among digital precoding and analog beamforming is carried out under ideal assumptions. More specifically, we will assume perfect and timely CSI available at the transmitters, ideal phase-shifters and combiners in the analog scheme and lack of any per-antenna power constraint in digital precoding. Recall that the maximum number of simultaneously scheduled users per BS is limited by the number of available RF chains \(P\) in the analog beamforming scheme, and by the number of BS antennas in the digital precoding schemes. Moreover, ABF and DP \begin{table}
\begin{tabular}{l l} \hline \hline
**Simulation time per drop** & 1 s \\
**Number of drops** & 10 \\
**Carrier frequency** & 28 GHz \\
**Number of FBs** & 100 \\
**FB bandwidth** & 10 MHz \\
**Subframe duration** & 1 ms \\
**Scheduling policy** & Proportional fair \\
**Thermal noise power spectral density** & \(-\)174 dBm/Hz \\
**Site transmit power** & 40 dBm \\
**BS antenna tilt** & 12\({}^{\circ}\) \\
**BS height** & 10 m \\
**BS antenna element gain** & 8 dBi \\
**BS antenna element front-to-back ratio** & 20 dB \\
**BS antenna element half-power beamwidth** & 70\({}^{\circ}\) (Both H and V planes) \\
**UE noise figure** & 7 dB \\
**UE speed** & 3 km/h \\
**UE antenna pattern gain** & 12 dBi \\
**UE antenna pattern front-to-back ratio** & 20 dB \\
**UE antenna pattern half-power beamwidth** & 45\({}^{\circ}\) (Both H and V planes) \\
**UE height** & 1.5 m \\
**Min UE-BS distance** & 10 m \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Simulation parameters. Figure 2: Seven-site layout considered for the simulations. Each site covers three 120\({}^{\circ}\) sectors, each one equipped with the antenna array boresight indicated by the arrows. NFS schemes keep the same set of scheduled UEs along the whole band, whereas DP FS can schedule a different set of users per FB. The average number of different UEs simultaneously allocated per subframe is reported in Table 2. It can be observed how the analog scheme makes the most of the number of parallel RF chains until reaching a certain number of chains, from which no more users are multiplexed. In particular, for the simulation setup in this work, even with 16 RF chains, the analog scheme only multiplexes 11.9 users on average. Regarding the DP schemes, they show a higher average number of multiplexed users per subframe than the ABF ones. It is worth noting also that the maximum number of UEs per BS is 16.7 and the DP FS scheme can meaningfully reach this number by performing a more elaborated per-FB allocation. Figure 3 shows the cumulative distribution function (CDF) of the user throughput for the algorithms under study. It is observed that, in the upper part of the CDF curves, the performance of ABF approaches the one of DP when the number of RF chains increases, but a significant gap in performance appears in the lower part, even when the number of RF chains is increased from four to sixteen. For the sake of completeness, the system performance having users in different conditions can be observed in Figures 4 and 5, which show the CDF curves of user throughput for only those users in LoS and NLoS, respectively. It can be seen that increasing the number of RF chains \(P\) in the analog scheme has a different impact depending on whether the user is in LoS or NLoS. Note that no benefit for NLoS users is obtained when increasing \(P\) beyond eight, since the greater the number of simultaneously scheduled users, the higher the inter-beam interference generated into the system. On the other hand, for the users in LoS, less affected by the interference, increasing \(P\) improves the user throughput, which reaches similar values to the ones obtained by the digital precoding schemes with sufficiently large \(P\).