## 5 Simulation Results
### Power Consumption  
Figure 15 shows the laser source power considering the mesh size, the placement of the SOA and the worst-case insertion loss. We assume that the efficiency of the laser source power is 20% [29]. If there is no SOA, the laser source power increases sharply as the mesh size increases. In the SOA-enabled HONoC, however, the laser source power is independent of the mesh size. Although additional power consumption due to the SOAs will be inevitable, it is expected to be a comparable trade-off owing to the laser source power savings that will be realized by incorporating this work.  
With common traffic patterns for NoCs, the simulation results in terms of power consumption in the conventional HONoC and the SOA-enabled HONoC are illustrated in Figure 16. We assume that the mesh size is \(8\times 8\) and SOAs are placed on every waveguide where the laser source power is the smallest. According to the previous studies, the power consumption of MR activation has been reported as 50 \(\upmu\)W [30]. Simulation was performed on the HONoC without SOAs and the SOA-enabled HONoCs optimized for SNR and power consumption, respectively. Power consumption is reduced by 16.26-35.86% when focusing on the SNR and by 21.81-37.68% when focusing on the total power consumption. There is a slight difference in power consumption between when optimizing for SNR and when optimizing for power consumption.  
Figure 15: Laser source power comparison between a conventional HONoC (without SOA) and SOA-enabled HONoC.  
Figure 17 shows the total power consumption according to the maximum hop count of possible paths without SOAs (\(h\)) and different traffic patterns when network size is \(8\times 8\). When \(h=0\), the laser source power can be reduced by the SOA gain; however, the efficiency of the SOA gain is low and the number of SOAs is the most. If \(h\
eq 0\), the number of SOAs in the network is reduced as \(h\) increases; however, the laser source power and single SOA power consumption increase.  
When \(h=4\), the number of SOAs is twice as high as when \(h=8\) and the power consumption increases. Furthermore, in the case of \(h=2\), the number of SOAs is three times higher than when \(h=8\); however, the power consumption is reduced slightly or similar. Therefore, the total power consumption in relation to \(h\) is hard to predict because it is determined by the total sum of the power consumption per unit SOA, the number of SOAs in the network and the laser source power. Simulation results show that the power consumption is the largest when \(h=0\); therefore, placing SOAs on all links is inefficient in terms of power consumption. Contrarily, the minimum power consumption is achieved when \(h=2\) and the overall power consumption of the SOA-enabled HONoC is reduced by 32.17-45.49%, compared to the conventional HONoC.  
Figure 18 shows the comparison of power consumption between the SOA-enabled HONoC and the conventional HONoC according to the mesh size and the hop count between SOAs in a random uniform pattern. The increase in the power consumption in the proposed HONoC is relatively low compared to that in the conventional HONoC because the insertion loss is independent of the longest  
Figure 16: Power consumption comparison between a conventional HONoC (without SOA) and SOA-enabled HONoC optimized for SNR and power consumption, respectively, for various traffic patterns.  
Figure 17: Power consumption of an SOA-enabled HONoC according to the SOA spacing for various traffic patterns.  
path. As a result, the power saving realized by the proposed approach becomes prominent as the mesh size grows.