## 3 System-Level Configuration
### System-Level Simulations
The total number of users in each sector is determined by the total number of subcarriers divided by the required number of subcarriers to achieve the specific bit rate. For Bt = 400 MHz and numerology 3, there are a total of 3300 subcarriers for data transmission. We kept the maximum number of subcarriers at 3300 to avoid intra-cell  
Figure 9: Coverage vs. transmitted power for the smart city scenario with a carrier frequency of 28 GHz with \(N_{u}=19800\), \(N_{vis}=576\). (sector) interference. When we consider 11 PRBs per user, i.e., \(N_{c}=132\), the maximum number of users per sector is \(3300/132=25\). When RISs are inserted in the border of the sector, a proportion of the 25 users are assigned to them. In this scenario, there are 12 sectors and four BSs, each one with 3 sectors. The total number of served users at the same time in the Stadium is 25 \(\times\) 12 = 300. Two different RIS sizes appear, since each RIS panel is divided into sub-panels when serving more than one user. We have \(N_{RIS}=192\) and 576 elements. When users are served with a direct link only from BS (100%BS + 0%RIS), we have a total average throughput of approximately 48 Gbps for 300 users (represented as a red line). In the stadium, there are 22 \(\times\) 3 = 66 RIS panels and 4 \(\times\) 3 = 12 TRPs. Considering the black and blue lines, when users at cell borders start to be served by RIS panels, 66 users from 300 (i.e., 66/300 = 0.22) must be subtracted, resulting in 300 - 66 = 234 users (i.e., 234/300 = 0.78) who are served by 12 TRPs, 78%BS + 22%RIS. For the pink and green lines, when 66 \(\times\) 3 = 198 users are served by RIS 198/300 = 0.66, the remaining 300 - 198 = 102 users (i.e., 102/300 = 0.34) are served by TRPs, 34%BS + 66%RIS. We observe that the throughput gain of curves with \(N_{s}=3\) compared to \(N_{s}=2\), is 1.5. There is no difference in throughput between users served by an RIS (0%BS) and users served by a BS (0%RIS). If more users are served by RIS panels (66%RIS), there is a throughput decrease compared to curves with fewer users (22%RIS), which is only noticeable for \(N_{s}=3\) (curves black and pink). For \(N_{s}=2\), there is no decrease in throughput when more users are served by the same RIS panel (curves blue and green). Note that in all curves, there is no decrease in throughput for increasing \(N_{u}\), because C-RAN operation combines transmitted signal power to RIS and BS, decreasing substantially inter-cell interference. We are also assuming perfect CSI in link-level results, and there is no intra-cell interference, as explained above. In Figure 11, the throughput performance versus \(N_{u}\) is shown for the stadium scenario, with two different maximum transmitted powers from BSs. Low-power BSs (LPBSs) transmit 250 mW, and high-power BSs (HPBS) transmit 3.16 W. We keep the maximum number of subcarriers of 3300 to avoid intra-sector interference. We assign 10 PRBs per user,  
Figure 10: Throughput vs. number of users for the stadium with pitch scenario, with 11 PRB, \(N_{tx}=64\), \(N_{rx}=16\), two different \(N_{ris}=576\) (22%RIS), \(N_{ris}=192\) (66%RIS), and \(P_{tx}=24\) dBm. i.e., \(N_{c}\) = 120, and 20 PRBs per user, \(N_{c}\) = 240. With 10 PRBs to each user, \(3300/120=27.5\) is the number of users per sector. The total number of served users in the stadium at the same time is \(27.5\times 12=330\). With 20 PRBs to each user, there are \(3300/240=13.75\) users per sector. The total number of users served at the same time in the stadium is \(13.75\times 12=165\). When users are exclusively served by the TRPs of BSs with direct links, i.e., \(100\%\)BS + \(0\%\)RIS, we have a total throughput of approximately 53 Gbps for 330 users (the pink line), and a total throughput of 48 Gbps for 165 users (the red line). Considering the case of 10 PRBs (blue lines), when 66 users at cell borders are served by an RIS (i.e., \(66/330=0.20\)), the remaining \(330-66=264\) users are served by TRPs, (i.e., \(264/330=0.80\)), \(80\%\)BS + \(20\%\)RIS,10 RB.