# Design of an Energy Efficient Future Base Station with Large-Scale Antenna System
## 4 Numerical Results
We assume a cell radius of 2000 m with a cell-hole radius of 100 m. The coverage of LS-MIMO-quipped BS can be extended more due to the beamforming effect from the LS antenna systems. The user locations are uniform-random, and an average is taken over 100,000 trials. To show the effectiveness of the proposed algorithm and structure more dominantly, we present the results of user locations between 1000 and 2000 m. The LS-MIMO can cover a wider area due to the beamforming effect. Figure 8: (**a**) total power consumption; and (**b**) power consumption of each component, when \(\varrho=5\) Gflop/W, \(P_{RF}=1\) W, \(P_{PA}=40\) W and 4 W, \(K=0.1\)\(N_{t}\); (**c**) total power consumption; and (**d**) power consumption of each component, when \(\varrho=50\) Gflop/W, \(P_{RF}=1\) W, \(P_{PA}=40\) W and 4 W, \(K=0.1\)\(N_{t}\). The results give us some important insight. First, when the number of TX antennas is relatively small, the PA power reduction provides further benefits for us in terms of the EE. Second, in contrast with the case of TP, in some regions, MF can provide a better EE than ZF. In future BS systems, it would also be quite general for the BS to only use a small portion of the equipped TX antennas by using an antenna selection scheme depending on the situation [16]. We can choose the ZF/MF/reference power/power reduction adaptively to improve the EE. The RSD-PS can help in this kind of work based on accumulated data. For example, to obtain the maximum EE with Figure 9, we choose ZF with a power reduction when the number of operating TX antennas is smaller than 190, and when the number of operating TX antennas is larger than 190, we choose the ZF reference. Now, let us fix some of parameters as \(N_{t}=400\), \(K=40\), \(\varrho=50\) Gflop/W, and \(P_{RF}=0.4\) W. In Figure 10, we present the total power consumption and power consumption of each component versus PA power reduction factor (Figure 10a,b) and TP and EE (Figure 10c,d). Figure 10: (**a**) total power consumption; and (**b**) power consumption of each component based on PA reduction factor, when \(N_{t}=400\) and \(K=40\), \(\varrho=50\) Gflop/W, and \(P_{RF}=0.4\) W; (**c**) TP; and (**d**) EE when \(N_{t}=400\) and \(K=40\), \(\varrho=50\) Gflop/W and \(P_{RF}=0.4\) W.  
Figure 9: (**a**) TP (bps); and (**b**) EE (bps/W), as the number of transmitter (TX) antennas increases, when \(\varrho=50\) Gflop/W, \(P_{RF}=1\) W, \(P_{PA}=40\) W and \(4\) W, \(K=0.1\)\(N_{t}\). We present the total power consumption and power consumption for each component versus the PA power reduction factor. Here, the PA power reduction factor refers to how much of the reference PA power consumption we use. For example, when the PA power reduction factor is 0.5, then we only use 50% of the reference PA power consumption. If the PA power reduction factor is less than one, the RF power consumes more power than the PA power consumption. If we observe the TP, it logarithmically increases as the PA reduction factor increases, i.e., the PA power consumption increases. This is quite obvious if we think of Shannon's channel capacity characteristic. However, if we observe the EE, it increases until a certain point, and then, it decreases, even if we increase the PA power consumption. This is due to the fact that, after the maximum EE point, the increase in power consumption is faster than the increase in TP because the channel capacity does not increase so much, even if we increase the TX power, when it goes to the bandwidth-limited regime. Keeping in mind the PA power adjustment case, now let us consider the RF power adjustment case. Figure 11 shows the total power consumption and power consumption of each component based on the RF power consumption between 0.1 W and 1 W, when \(N_{t}=400\) and \(K=40\), VLSI efficiency \(\varrho=50\) Gflop/W and \(P_{PA}=160\) W. The total power consumption increases linearly as the RF power consumption increases. In this case, when the RF power consumes more than 0.4 W, it consumes more than the PA power consumption.